WO2023047571A1 - Catalyst deterioration diagnosis device - Google Patents

Catalyst deterioration diagnosis device Download PDF

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Publication number
WO2023047571A1
WO2023047571A1 PCT/JP2021/035337 JP2021035337W WO2023047571A1 WO 2023047571 A1 WO2023047571 A1 WO 2023047571A1 JP 2021035337 W JP2021035337 W JP 2021035337W WO 2023047571 A1 WO2023047571 A1 WO 2023047571A1
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Prior art keywords
signal
timing
interval
inversion
catalyst
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PCT/JP2021/035337
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French (fr)
Japanese (ja)
Inventor
祐也 山田
航 鈴木
亮 富井
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ヤマハ発動機株式会社
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Application filed by ヤマハ発動機株式会社 filed Critical ヤマハ発動機株式会社
Priority to DE112021002324.1T priority Critical patent/DE112021002324T5/en
Priority to PCT/JP2021/035337 priority patent/WO2023047571A1/en
Priority to FR2209606A priority patent/FR3127528A1/en
Publication of WO2023047571A1 publication Critical patent/WO2023047571A1/en

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N11/00—Monitoring or diagnostic devices for exhaust-gas treatment apparatus, e.g. for catalytic activity
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/0807—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/14—Introducing closed-loop corrections
    • F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
    • F02D41/1439—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the position of the sensor
    • F02D41/1441—Plural sensors
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/14—Introducing closed-loop corrections
    • F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
    • F02D41/1444—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases
    • F02D41/1454—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being an oxygen content or concentration or the air-fuel ratio
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2550/00—Monitoring or diagnosing the deterioration of exhaust systems
    • F01N2550/02—Catalytic activity of catalytic converters
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2560/00—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics
    • F01N2560/02—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics the means being an exhaust gas sensor
    • F01N2560/025—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics the means being an exhaust gas sensor for measuring or detecting O2, e.g. lambda sensors
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2560/00—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics
    • F01N2560/14—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics having more than one sensor of one kind
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2900/00—Details of electrical control or of the monitoring of the exhaust gas treating apparatus
    • F01N2900/04—Methods of control or diagnosing
    • F01N2900/0416—Methods of control or diagnosing using the state of a sensor, e.g. of an exhaust gas sensor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/14—Introducing closed-loop corrections
    • F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
    • F02D41/1493—Details
    • F02D41/1495—Detection of abnormalities in the air/fuel ratio feedback system
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/40—Engine management systems

Definitions

  • This invention relates to a catalyst deterioration diagnostic device that diagnoses deterioration of a catalyst that purifies exhaust gas emitted from an engine.
  • a catalyst deterioration diagnosis device that diagnoses the deterioration of the catalyst that purifies the exhaust gas emitted from the engine.
  • an upstream oxygen concentration sensor and a downstream oxygen concentration sensor are provided respectively upstream and downstream of the catalyst in the flow direction of the exhaust gas.
  • the catalyst deterioration diagnosis device counts the duration of the rich/lean state, and when the duration reaches a predetermined delay time, Operate the engine to reverse the increase/decrease in the amount of fuel supplied.
  • Deterioration diagnosis of the catalyst is performed based on the output signal of the downstream oxygen concentration sensor when the reversal of the increase/decrease of the fuel amount is controlled based on the rich/lean state of the output signal of the upstream oxygen concentration sensor.
  • a set of abrupt reversals and subsequent reversals occurs in the output signal of the upstream oxygen concentration sensor, and the abrupt signal
  • the interval between the earlier and later inversions in the set of inversions (hereafter referred to as the "length of the set of abrupt signal inversions") can be long.
  • a sudden signal reversal set shorter than the delay time is generated, the increase and decrease of the fuel amount are not reversed, but a sudden signal longer than the delay time If a reversal set occurs, the increase and decrease of the fuel amount will be reversed.
  • Patent Document 1 The catalyst deterioration diagnosis based on the output signal of the downstream oxygen concentration sensor in Patent Document 1 is based on the premise that the cycle of reversing the increase and decrease of the fuel amount is a cycle suitable for diagnosis. Therefore, if the interval at which the increase and decrease of the fuel quantity are reversed changes due to the long sudden signal reversal group, the chances of diagnosing deterioration of the catalyst are reduced.
  • Patent Document 1 by lengthening the delay time, it is conceivable to prevent the increase and decrease of the fuel quantity from being reversed even if a long sudden signal inversion group occurs.
  • Rich in the output signal of an upstream oxygen concentration sensor that is arranged upstream of the catalyst in the flow direction of the exhaust gas discharged from the combustion chamber of the engine and outputs a signal according to whether the air-fuel ratio of the air-fuel mixture is rich or lean. / operating the engine such that an increase/decrease reversal of the amount of fuel supplied to the engine is performed based on the reversal of the lean condition; a first signal inversion timing at which the rich/lean state of the output signal of the upstream oxygen concentration sensor is inverted; and a second signal inversion timing at which the rich/lean state of the output signal of the upstream oxygen concentration sensor is inverted following the first signal inversion timing.
  • the first reversal determination period is defined as the interval from the timing at which it is determined to reverse the increase/decrease of the fuel amount based on the reversal of the rich/lean state
  • a signal invalid period is provided in a period between the first signal inversion timing and the second signal inversion timing when the engine is operated such that the signal inversion interval is equal to the catalyst deterioration diagnosis interval, and the signal
  • the abrupt signal inversion group occurs during the invalid period, the length of the abrupt signal inversion group is longer than the first inversion determination period, and the abrupt signal inversion group is the first signal inversion timing and the abrupt signal inversion group. If it falls within the period between the second signal inversion timing, the sudden signal inversion group is ignored and the increase/decrease of the fuel amount is controlled so as not to be reversed.
  • the catalyst deterioration diagnosis device operates the engine so that the increase/decrease of the amount of fuel supplied to the engine is reversed based on the reversal of the rich/lean state of the output signal of the upstream oxygen concentration sensor. Further, the catalyst deterioration diagnosis device diagnoses deterioration of the catalyst according to the output signal of the downstream oxygen concentration sensor when the engine is operated such that the signal inversion interval is equal to the catalyst deterioration diagnosis interval. Further, the catalyst deterioration diagnosis device provides a signal invalid period between the first signal inversion timing and the second signal inversion timing when the engine is operated such that the signal inversion interval is the catalyst deterioration diagnosis interval.
  • a sudden signal inversion group occurs in the output signal of the upstream oxygen concentration sensor, the length of the sudden signal inversion group is longer than the first inversion determination period, and the sudden signal inversion group
  • the sudden signal inversion set is ignored and the increase/decrease of the fuel quantity is not reversed.
  • the signal invalid period is not provided, the increase/decrease of the fuel quantity based on the sudden signal reversal group is reversed when the sudden signal reversal group as described above occurs.
  • the interval between the increase/decrease reversal of the fuel amount becomes shorter than the catalyst deterioration diagnosis interval, and deterioration diagnosis of the catalyst cannot be performed. That is, the chances of diagnosing deterioration of the catalyst are reduced.
  • by lengthening the first reversal determination period instead of providing the signal invalid period it is possible to prevent the reversal of the increase/decrease of the fuel amount based on the sudden signal reversal group as described above from occurring. can.
  • the first reversal determination period is made too long, there is a high possibility that the increase/decrease of the fuel amount will not be reversed even when the output signal of the upstream oxygen concentration sensor normally reverses.
  • the interval between the increase/decrease reversal of the fuel amount becomes longer than the catalyst deterioration diagnosis interval, and deterioration diagnosis of the catalyst cannot be performed. That is, the chances of diagnosing deterioration of the catalyst are reduced.
  • the signal invalid period is provided between the first signal inversion timing and the second signal inversion timing, thereby ignoring the sudden signal inversion group and increasing the fuel amount. / Decrease is not reversed. This ensures that the increase/decrease in fuel quantity is not reversed based on a long set of abrupt signal reversals, but that the fuel quantity increases when a normal reversal occurs in the output signal of the upstream oxygen concentration sensor. /decrease can be reversed. As a result, it is possible to prevent the interval between the increase/decrease reversal of the fuel amount from becoming shorter or longer than the catalyst deterioration diagnosis interval, thereby securing an opportunity to enable deterioration diagnosis of the catalyst.
  • a catalyst deterioration diagnosis device may have the following configuration.
  • the first signal inversion timing and then the output signal of the upstream oxygen concentration sensor at the first signal inversion timing When the second reversal determination period is defined as the interval from the timing at which it is determined to reverse the increase/decrease of the fuel amount based on the reversal of the rich/lean state,
  • the start timing of the signal invalid period is controlled so as to be the timing when the second inversion determination period has elapsed after the first signal inversion timing.
  • the start timing of the signal invalid period is controlled to be the timing after the first signal inversion timing and the second inversion determination period.
  • the start timing of the signal invalid period is after the timing at which the second inversion determination period has passed after the first signal inversion timing.
  • the increase/decrease of the fuel amount is reversed based on the sudden signal inversion group that occurs during the period from the timing at which the second inversion determination period has elapsed to the start timing of the signal invalid period. There are times when it is done.
  • the interval at which the increase and decrease of the fuel amount are reversed becomes shorter than the catalyst deterioration diagnosis interval, and the chances of enabling deterioration diagnosis of the catalyst decrease. From the above, in this configuration, deterioration diagnosis of the catalyst can be performed more effectively than in the case where the start timing of the signal invalid period is after the timing at which the second inversion determination period has passed after the first signal inversion timing. You can secure as many opportunities as possible.
  • a catalyst deterioration diagnosis device may have the following configuration. Control is performed so that the signal invalid period is not provided except when the engine is operated such that the signal inversion interval is equal to the catalyst deterioration diagnosis interval.
  • control to provide a signal invalid period is not performed except when the engine is operated such that the signal inversion interval is equal to the catalyst deterioration diagnosis interval, that is, when the catalyst deterioration diagnosis is not performed. Therefore, it is possible to simplify the control for reversing the increase/decrease of the fuel amount when the catalyst deterioration diagnosis is not performed.
  • a catalyst deterioration diagnosis device may have the following configuration.
  • the signal invalid period is controlled to be set to different lengths according to the operating conditions of the engine.
  • the signal invalid period can be set to an appropriate period according to the operating state of the engine.
  • the engine fuel may be either gasoline fuel, alcohol fuel, mixed fuel of gasoline and alcohol, or light oil.
  • the type of engine may be a 4-stroke engine or a 2-stroke engine.
  • the engine may or may not have a canister.
  • the engine may or may not have a forced induction device.
  • the supercharger may be a turbocharger or a supercharger.
  • the type of engine may be a single-cylinder engine with a single combustion chamber or a multi-cylinder engine with multiple combustion chambers.
  • the form of arrangement of the plurality of cylinders (plurality of combustion chambers) in the multi-cylinder engine is not particularly limited.
  • the cycle of reversal of increase/decrease in the amount of fuel supplied to a plurality of combustion chambers is the same or substantially the same. Timings at which fuel is supplied to the plurality of combustion chambers may differ from each other. When the number of fuel chambers is four or more, the timing at which fuel is supplied to two of the plurality of combustion chambers may be the same.
  • the use of the engine is not particularly limited.
  • the engine may constitute a vehicle, a ship, or the like. Further, when the engine constitutes a vehicle, the vehicle includes, for example, an automobile and a straddle-type vehicle.
  • a straddle-type vehicle refers to a vehicle in general in which a rider (driver) rides while straddling a saddle.
  • a straddle-type vehicle may or may not have wheels.
  • Straddle-type vehicles include motorcycles, motor tricycles, four-wheeled buggies (ATVs: All Terrain Vehicles), snowmobiles, personal water crafts, and the like.
  • the catalyst purifies the exhaust gas discharged from the combustion chamber of the engine.
  • the catalyst is a three-way catalyst (TWC), an oxidation catalyst (DOC), an SCR catalyst for NOx selective reduction, a NOx storage reduction catalyst (LNT), or the like.
  • a three-way catalyst is a catalyst that removes three substances, mainly hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx) in exhaust gas, which are atmospheric pollutants, by oxidizing or reducing them. That's what I mean.
  • a three-way catalyst is, for example, a catalyst containing platinum (Pt), palladium (Pd) and rhodium (Rh).
  • the three-way catalyst oxidizes or reduces hydrocarbons to water and carbon dioxide, carbon monoxide to carbon dioxide, and nitrogen oxides to nitrogen, respectively, thereby purifying the exhaust gas.
  • the NOx selective reduction SCR catalyst contains at least one selected from the group consisting of metal-substituted zeolite, vanadium, titania, tungsten oxide, silver, and alumina.
  • the NOx storage reduction catalyst is alkali metal and/or alkaline earth metal and the like. Alkali metals are K, Na, Li and the like. Alkaline earth metals are Ca and the like.
  • the catalyst may be a catalyst that removes any one or two of hydrocarbons, carbon monoxide and nitrogen oxides. The catalyst need not be a redox catalyst.
  • the catalyst may be an oxidation catalyst or a reduction catalyst that removes air pollutants by either oxidation or reduction alone.
  • the catalyst has a structure in which a noble metal having an exhaust gas purifying action is adhered to a base material.
  • the catalyst may be a metal-based catalyst or a ceramic-based catalyst.
  • the upstream oxygen concentration sensor and the downstream oxygen concentration sensor detect the oxygen concentration in the exhaust gas discharged from the combustion chamber of the engine.
  • the upstream oxygen concentration sensor and the downstream oxygen concentration sensor may be collectively referred to as oxygen concentration sensors.
  • Oxygen concentration sensors include O2 sensors and linear A/F sensors.
  • the O2 sensor detects that the oxygen concentration in the exhaust gas is higher than the first concentration and lower than the second concentration.
  • the first concentration may be higher than or the same as the second concentration.
  • a linear A/F sensor continuously detects changes in oxygen concentration in the exhaust gas. Whether the air-fuel ratio of the air-fuel mixture is rich or lean can be detected based on the signal of the upstream oxygen concentration sensor.
  • the target air-fuel ratio is the stoichiometric air-fuel ratio.
  • the target air-fuel ratio may be a value or range including the stoichiometric air-fuel ratio, or may be a value or range slightly deviating from the stoichiometric air-fuel ratio.
  • the output signal of the upstream oxygen concentration sensor When the air-fuel ratio of the air-fuel mixture is rich, the output signal of the upstream oxygen concentration sensor is rich, and when the air-fuel ratio of the air-fuel mixture is lean, the output signal of the upstream oxygen concentration sensor is lean.
  • the rich state of the output signal of the upstream oxygen concentration sensor is, for example, a state in which the voltage value or current value of the output signal is greater than the first value.
  • the lean state of the output signal of the upstream oxygen concentration sensor is a state in which the voltage value or current value of the output signal is smaller than a second value equal to or smaller than the first value.
  • the oxygen concentration sensor has a sensor element portion composed of a solid electrolyte body mainly composed of zirconia, for example. When the sensor element portion of the oxygen concentration sensor is heated to a high temperature and activated, the oxygen concentration sensor can detect the oxygen concentration.
  • the reversal of the rich/lean state of the output signal of the upstream oxygen concentration sensor means that the output signal of the upstream oxygen concentration sensor changes from a rich state indicating that the air-fuel ratio of the air-fuel mixture is rich to One is switching to a lean state indicating that the air-fuel ratio of the air-fuel mixture is lean, and the other is that the output signal of the upstream oxygen concentration sensor switches from the lean state to the rich state.
  • the output signal of the upstream oxygen concentration sensor 76 switches from rich to lean.
  • the output signal of the upstream oxygen concentration sensor 76 switches from lean to rich.
  • the first signal inversion timing is the timing at which the output signal of the upstream oxygen concentration sensor switches to the low state or the timing at which the output signal of the upstream oxygen concentration sensor switches to the rich state.
  • the second signal inversion timing means that the output signal of the upstream oxygen concentration sensor changes to the rich state when the output signal of the upstream oxygen concentration sensor switches to the lean state at the first signal inversion timing. It is the timing of switching.
  • the second signal inversion timing means that when the output signal of the upstream oxygen concentration sensor switches to the rich state at the first signal inversion timing, the output signal of the upstream oxygen concentration sensor is in the lean state. It is the timing of switching to
  • the second signal inversion timing at which the rich/lean state of the output signal of the upstream oxygen concentration sensor is inverted after the first signal inversion timing means that a sudden signal inversion group occurs. It is the timing at which the rich/lean state of the output signal of the upstream oxygen concentration sensor is inverted next to the first signal inversion timing in the state where the oxygen concentration sensor is not in the state.
  • the reversal of the increase/decrease of the fuel amount means that the amount of fuel supplied to the combustion chamber is switched from increasing to decreasing, and the amount of fuel supplied to the combustion chamber is decreased. It is to switch from a state of increasing to a state of increasing.
  • the length of the second inversion determination period may be the same as or different from the length of the first inversion determination period.
  • the reversal of the increase/decrease of the fuel amount is determined.
  • the fuel increase/decrease reversal may be performed when the fuel increase/decrease reversal is determined, or may be performed when a predetermined time has elapsed after the fuel increase/decrease reversal has been determined. may be broken.
  • the catalyst deterioration diagnosis device is a device that has a processor and a storage device and executes at least the catalyst deterioration diagnosis and fuel amount control described in the present invention and this specification.
  • the catalyst deterioration diagnosis device may be, for example, an ECU (Electronic Control Unit).
  • the processor is configured to perform the control recited in the claims.
  • Processors include microcontrollers, CPUs (Central Processing Units), microprocessors, multiprocessors, application specific integrated circuits (ASICs), programmable logic circuits (PLCs), field programmable gate arrays (FPGAs) and herein Any other circuitry capable of diagnosing the state of catalyst deterioration and controlling fuel quantity described is included.
  • a storage device is a device for saving or storing data and programs. Storage devices include semiconductor memories such as registers and cache memories, main memory (main memory device/RAM), storage (external memory device/auxiliary memory device), and the like.
  • the catalyst deterioration diagnosis device diagnoses the deterioration state of the catalyst based on the signal from the downstream oxygen concentration sensor. For example, the catalyst deterioration diagnosis device diagnoses the deterioration state of the catalyst based on a catalyst deterioration judgment value related to deterioration of the catalyst obtained from the output signal of the downstream oxygen concentration sensor and a preset catalyst deterioration judgment threshold value. do. For example, the catalyst deterioration diagnosis device diagnoses the deterioration state of the catalyst by comparing the catalyst deterioration judgment value and the catalyst deterioration judgment threshold value.
  • the "catalyst deterioration diagnosis interval suitable for catalyst deterioration diagnosis” includes the signal inversion interval when the output signal of the downstream oxygen concentration sensor used for catalyst deterioration diagnosis is detected.
  • the engine is operated such that the signal inversion interval is a catalyst deterioration diagnosis interval suitable for the catalyst deterioration diagnosis” means that the fuel amount is increased for the catalyst deterioration diagnosis.
  • the signal inversion interval becomes a catalyst deterioration diagnosis interval suitable for diagnosing catalyst deterioration, and as a result of controlling the fuel amount instead of diagnosing catalyst deterioration, the signal inversion interval becomes suitable for diagnosing catalyst deterioration. This includes providing suitable catalyst deterioration diagnostic intervals.
  • the catalyst deterioration diagnosis interval is set so that the output signal of the downstream oxygen concentration sensor used for the catalyst deterioration diagnosis is detected.
  • This signal inversion interval is the same as any signal inversion interval when the deterioration diagnosis of the catalyst is not performed.
  • the plurality of signal inversion intervals may not be exactly the same. That is, the catalyst deterioration diagnosis interval may be within a numerical range.
  • the length of the sudden signal inversion set means that when the output signal of the upstream oxygen concentration sensor switches to the lean state at the first signal inversion timing, the length of the sudden signal inversion set before the rich/lean state.
  • the length of the sudden signal inversion set means that when the output signal of the upstream oxygen concentration sensor switches to the rich state at the first signal inversion timing, the length of the sudden signal inversion set before the rich/rich state is reached.
  • the abrupt signal inversion group occurs during the signal invalid period means that the rich/lean state before the abrupt signal inversion group is inverted and the rich/lean state after the abrupt signal inversion group occurs within the signal invalid period.
  • the abrupt signal inversion group occurs during the signal invalid period means that at least the first inversion of the two inversions forming the abrupt signal inversion group occurs within the signal invalid period. .
  • the catalyst deterioration diagnosis device may not ignore the sudden pair of signal inversions. For example, if the length of the period from the end of the signal invalid period to the rich/lean state after the sudden signal inversion group is longer than or equal to the first signal inversion period, the catalyst deterioration diagnosis device cannot ignore the sudden signal inversion group.
  • the fuel amount may be controlled without In other words, if the length of the period from the end of the signal invalid period to the rich/lean state after the sudden signal inversion group is shorter than the first signal inversion period, the catalyst deterioration diagnostic device selects the sudden signal inversion group. ignore.
  • "setting the signal invalid period to a different length according to the operating state of the engine” means, for example, that the catalyst deteriorates according to the rotational speed of the engine and/or the load of the engine. To change the length of a signal invalid period according to a catalyst deterioration diagnosis interval when the diagnosis interval is changed.
  • a simulator provided between the catalyst deterioration diagnosis device and the upstream oxygen concentration sensor can be used to confirm whether or not the control by the catalyst deterioration diagnosis device of the present invention described in the claims is being performed. can be done.
  • a synthesized signal obtained by combining the pseudo signal generated by the simulator and the output signal of the upstream oxygen concentration sensor is input to the catalyst deterioration diagnosis device.
  • a pseudo signal is input when the engine is operated such that the signal inversion interval in the output signal of the upstream oxygen concentration sensor is equal to the catalyst deterioration diagnosis interval. If a sudden signal inversion group occurs in the output signal of the upstream oxygen concentration sensor, the pseudo signal is input again.
  • the simulator is used to acquire the first reversal determination period, for example, according to the following procedure.
  • synthesis A dummy signal is input so that the rich/lean state of the signal is inverted.
  • the spurious signal is input for only a short time and the rich/lean state of the synthesized signal quickly reverts. Without changing conditions such as the operating state of the engine, such a pseudo signal is repeatedly input such that ⁇ T is gradually shortened from a relatively long period.
  • FIGS. 10(a) and 10(b) show that the inversion of the output signal of the upstream oxygen concentration sensor at the starting point of ⁇ T is all switching to the rich state
  • FIGS. 10(d) and 10(e). ) shows the case where the reversal of the output signal of the upstream oxygen concentration sensor at the beginning of ⁇ T is all a switch to the lean state.
  • the timing of the first reversal of the fuel amount increase/decrease after the second signal reversal timing is after the second signal reversal timing when there is no pseudo signal, as shown in FIGS.
  • .DELTA.T is equal to or longer than the predetermined time
  • the timing fuel amount increases/decreases in the same reversal as shown in FIGS.
  • the timing of the first reversal of the fuel amount increase/decrease after the second signal reversal timing is the timing when the first reversal determination period has passed after the second signal reversal timing, and after the second signal reversal timing
  • the first reversal determination period can be acquired by the above-described procedure at any timing when a time longer than the first reversal determination period has elapsed.
  • the second inversion determination period can also be acquired in the same procedure as described above. Next, for example, as shown in FIGS. 11(a) and 11(d), the combined signal is longer than the first inversion determination period and falls within the period between the first signal inversion timing and the second signal inversion timing.
  • a pseudo signal is input so as to generate such a signal inversion pair. That is, the pseudo signal generates a dummy of the sudden signal inversion set. For example, the dummy signal is input so that the previous inversion in the signal inversion group occurs when the second inversion determination period or more has elapsed from the first signal inversion timing.
  • the catalyst deterioration diagnosis device of the present invention according to whether or not the increase/decrease of the fuel amount is reversed based on the signal inversion set by the pseudo signal. can be done.
  • 11(b) and (e) show the case where the fuel amount increase/decrease is not reversed
  • FIGS. 11(c) and (f) show the case where the fuel amount increase/decrease is reversed.
  • Whether the increase/decrease of the fuel amount has been reversed based on the signal inversion set is determined by the reversal of the increase/decrease of the fuel amount based on the reversal of the rich/lean state of the output signal of the upstream oxygen concentration sensor at the first signal reversal timing. and the timing of reversal of the fuel amount increase/decrease based on the reversal of the rich/lean state of the output signal of the upstream oxygen concentration sensor at the second signal reversal timing. It can be confirmed by whether or not it has been reversed.
  • Information about when the signal inversion interval was the catalyst deterioration diagnosis interval (when the catalyst deterioration diagnosis was performed) can be obtained using, for example, an external scan tool.
  • the external scan tool is a device that reads the results of the catalyst deterioration diagnosis, the information used for this diagnosis, the operating conditions when this diagnosis was made, etc., from the catalyst deterioration diagnosis device.
  • the external scan tool is detachably connected to the catalyst deterioration diagnosis device.
  • the external scan tool may be able to wirelessly communicate with the catalyst deterioration diagnostic device.
  • the operating conditions at the time of diagnosis acquired by the external scan tool include, for example, engine speed, intake air amount, throttle valve opening, intake pressure, fuel amount correction coefficient, and the like.
  • the fuel amount correction factor is a correction factor for the basic fuel supply amount.
  • Timing at which the increase/decrease of the fuel amount is reversed may be acquired based on a signal sent from the catalyst deterioration diagnosis device to the fuel supply device that supplies fuel to the engine.
  • At least one (one) of a plurality of options includes all conceivable combinations of the plurality of options.
  • At least one (one) of the multiple options may be any one of the multiple options, or may be all of the multiple options.
  • at least one of A, B and C may be A only, B only, C only, A and B, A and C There may be, it may be B and C, or it may be A, B and C.
  • a and/or B means that it can be A, it can be B, it can be both A and B.
  • the invention may include a plurality of that element. good. Also, the invention may have only one of this component.
  • the catalyst deterioration diagnosis device of the present invention it is possible to ensure many opportunities for catalyst deterioration diagnosis.
  • FIG. 1 is a diagram for explaining a catalyst deterioration diagnosis device according to a first embodiment of the present invention.
  • 2A to 2C are diagrams for explaining Comparative Example 1 with respect to the first embodiment.
  • FIG. 2(a) is a diagram for explaining changes in the output signal of the upstream oxygen concentration sensor in Comparative Example 1
  • FIG. 2(c) is a diagram for explaining changes in the amount of fuel when a sudden signal reversal group K2a occurs
  • FIG. 2(c) shows a sudden signal reversal group K1b or a sudden
  • FIG. 10 is a diagram for explaining changes in the amount of fuel when a signal inversion group K2b is generated
  • FIGS. 3A and 3B are diagrams for explaining Comparative Example 2 with respect to the first embodiment.
  • FIG. 3(a) is a diagram for explaining changes in the output signal of the upstream oxygen concentration sensor in Comparative Example 2, and FIG. It is a figure for demonstrating the change of the fuel amount when it generate
  • FIG. 4 is a diagram for explaining a straddle-type vehicle equipped with a catalyst deterioration diagnosis device according to a second embodiment of the present invention.
  • FIG. 5 is a schematic diagram showing the configuration of an engine unit controlled by a catalyst deterioration diagnosis device according to a third embodiment of the invention.
  • FIG. 6(a) is a flow chart showing the flow of processing when diagnosing deterioration of the catalyst in the catalyst deterioration diagnosis device of the fourth embodiment of the present invention, and FIG. 6(b) is the flow of FIG. 6(a).
  • FIG. 10 is a diagram showing changes in the amount of fuel during deterioration diagnosis of the catalyst when processing is performed along .
  • FIG. 7 is a diagram for explaining the relationship between the rich/lean state change of the upstream oxygen concentration sensor and the fuel amount increase/decrease, and the details of the fuel amount increase and decrease.
  • FIG. 8 is a flow chart for explaining the flow of processing including catalyst deterioration diagnosis in the catalyst deterioration diagnosis device according to the fifth embodiment of the present invention.
  • FIG. 9(a) is a diagram for explaining the signal invalid period when the engine is operated so that the catalyst deterioration diagnosis interval is lengthened by the catalyst deterioration diagnosis device according to the sixth embodiment of the present invention.
  • FIG. 10(a) shows that the reversal of the output signal of the upstream oxygen concentration sensor at the starting point of ⁇ T is all switching to the rich state, and the fuel amount when ⁇ T in the combined signal is longer than the first reversal determination period.
  • FIG. 10(a) shows that the reversal of the output signal of the upstream oxygen concentration sensor at the starting point of ⁇ T is all switching to the rich state, and the fuel amount when ⁇ T in the combined signal is longer than the first reversal determination period.
  • FIG. 10(b) shows that the inversion of the output signal of the upstream oxygen concentration sensor at the starting point of ⁇ T is all switching to the rich state, and ⁇ T in the combined signal is the first
  • FIG. 10(c) is a diagram for explaining changes in the amount of fuel when the inversion determination period or less is reached
  • FIG. 10(d) is a diagram for explaining changes in the fuel amount when no pseudo signal is included.
  • 10(e) is an output signal of the upstream oxygen concentration sensor at the starting point of ⁇ T
  • FIG. is a switch to a lean state
  • ⁇ T in the combined signal is less than or equal to the first reversal determination period.
  • FIG. 10 is a diagram for explaining changes in the amount of fuel when the inversion of the output signal of the concentration sensor is switched to the lean state and the combined signal does not contain the pseudo signal;
  • FIGS. 11(a) to 11(f) are diagrams for explaining part of the procedure for confirming whether or not the control by the catalyst deterioration diagnosis device of the present invention is being performed.
  • FIG. 11(a) is a diagram for explaining the dummies of the abrupt signal inversion group generated by the pseudo signal during the period from when the output signal of the upstream oxygen concentration sensor switches to the rich state to when it switches to the lean state.
  • FIG. 11(b) is a diagram for explaining changes in the fuel amount when the signal of FIG. 11(c) is a diagram for explaining changes in the fuel amount when the signal of FIG.
  • FIG. 11(a) is input to the catalyst deterioration diagnosis device in a state where no signal invalid period is provided;
  • ) is a diagram for explaining the dummies of the sudden signal reversal group generated by the pseudo signal during the period from when the output signal of the upstream oxygen concentration sensor switches to the lean state to the rich state;
  • FIG. 11(e) is a diagram for explaining changes in the fuel amount when the signal of FIG. 11(d) is input to the catalyst deterioration diagnosis device in a state in which the signal invalid period is provided;
  • 11B is a diagram for explaining changes in the amount of fuel when the signal of FIG. 11D is input to the catalyst deterioration diagnosis device in a state in which no signal invalid period is provided;
  • a catalyst deterioration diagnostic device 80 according to a first embodiment of the present invention will be described with reference to FIG.
  • the catalyst deterioration diagnosis device 80 of the first embodiment is provided for the engine unit 11.
  • the engine unit 11 has an engine 20 , a catalyst 53 , an upstream oxygen concentration sensor 76 and a downstream oxygen concentration sensor 77 .
  • Engine 20 may be a four-stroke engine or a two-stroke engine.
  • the upstream oxygen concentration sensor 76 is arranged upstream of the catalyst 53 in the flow direction of the exhaust gas discharged from the combustion chamber 30 of the engine 20 .
  • the output signal of the upstream oxygen concentration sensor 76 is a signal corresponding to whether the air-fuel ratio of the air-fuel mixture is rich or lean.
  • a rich state of the output signal of the upstream oxygen concentration sensor 76 indicating that the air-fuel ratio of the air-fuel mixture is rich is, for example, a state in which the value Vj of the output signal is greater than the first value Vj1.
  • a lean state of the output signal of the upstream oxygen concentration sensor 76 indicating that the air-fuel ratio of the air-fuel mixture is lean is, for example, a state in which the value Vj of the output signal is smaller than the second value Vj2.
  • the second value Vj2 is equal to or less than the first value Vj1.
  • the downstream oxygen concentration sensor 77 is arranged downstream of the catalyst 53 in the flow direction of the exhaust gas.
  • the catalyst deterioration diagnosis device 80 controls the fuel amount H.
  • the catalyst deterioration diagnosis device 80 operates the engine 20 so that the increase/decrease of the fuel amount H is reversed based on the rich/lean state reversal of the output signal of the upstream oxygen concentration sensor 76 .
  • the catalyst deterioration diagnosis device 80 detects the timing (for example, the signal inversion timings T1a, T3a, and T5a in FIG. 1) at which the output signal of the upstream oxygen concentration sensor 76 switches to the lean state and the timing (for example, the timing in FIG. 1) after the inversion determination period R1 has passed.
  • the catalyst deterioration diagnosis device 80 increases the fuel amount H based on this determination. That is, the increase/decrease of the fuel amount H is reversed. Further, the catalyst deterioration diagnosis device 80 detects the timing (for example, the timing signal inversion timings T2a and T4a in FIG. 1) at which the output signal of the upstream oxygen concentration sensor 76 switches to the rich state, and the timing (for example, timing signal inversion timings T2a and T4a in FIG.
  • the inversion determination period R2 may be the same as the inversion determination period R1, or may be different from the inversion determination period R1.
  • the catalyst deterioration diagnosis device 80 reduces the fuel amount H based on this determination. That is, the increase/decrease of the fuel amount H is reversed.
  • An interval from the inversion timing is defined as a signal inversion interval.
  • the second signal inversion timing is the signal inversion timing T2a in FIG.
  • the first signal inversion timing is the signal inversion timing T2a in FIG.
  • the second signal inversion timing is the signal inversion timing T3a in FIG.
  • the first signal inversion timing may be the signal inversion timing T3a, the signal inversion timing T4a, or the signal inversion timing T5a in FIG.
  • the inversion determination period R2 corresponds to the first inversion determination period of the present invention.
  • the inversion determination period R1 corresponds to the first inversion determination period of the present invention.
  • the catalyst deterioration diagnosis device 80 controls the engine so that the signal inversion interval, which is the interval between the first signal inversion timing and the second signal inversion timing, becomes the catalyst deterioration diagnosis intervals W1 and W2 suitable for diagnosing the deterioration of the catalyst 53 . 20 is operated, based on the signal of the downstream oxygen concentration sensor 77, the deterioration diagnosis of the catalyst 53 is performed.
  • the catalyst deterioration diagnosis interval W1 is the catalyst deterioration diagnosis interval when switching to the lean state at the first signal inversion timing.
  • the catalyst deterioration diagnosis interval W2 is the catalyst deterioration diagnosis interval when the state is switched to the rich state at the first signal inversion timing.
  • the catalyst deterioration diagnosis interval W1 and the catalyst deterioration diagnosis interval W2 may be the same or different.
  • the catalyst deterioration diagnosis device 80 detects the signal inversion intervals between the first signal inversion timing and the second signal inversion timing when the engine 20 is operated such that the signal inversion intervals are equal to the catalyst deterioration diagnosis intervals W1 and W2.
  • signal invalid periods M1 and M2 are provided to control the fuel amount H.
  • the signal invalid period M1 is a signal invalid period when switching to the lean state at the first signal inversion timing.
  • the signal invalid period M2 is a signal invalid period when switching to the rich state at the first signal inversion timing.
  • the length of the signal invalid period M1 and the length of the signal invalid period M2 may be the same or different.
  • the start timing and end timing of the signal invalid periods M1 and M2 are not limited to the timings shown in FIG.
  • the sudden signal inversion group is suddenly generated in the period between the first signal inversion timing and the second signal inversion timing. may occur.
  • a set of abrupt signal inversions is a set of rich/lean state inversions followed by rich/lean state inversions in the upstream oxygen concentration sensor 76 output signal.
  • a sudden signal inversion group occurs during the signal invalid period M1, and the length of the sudden signal inversion group is longer than the inversion determination period R2 (first inversion determination period), and When the sudden signal inversion set is between the first signal inversion timing and the second inversion timing, the sudden signal inversion set is ignored and the increase/decrease of the fuel amount H is reversed.
  • the catalyst deterioration diagnosis device 80 generates a sudden signal inversion group during the signal invalid period M2, and the length of the sudden signal inversion group is longer than the inversion determination period R1 (first inversion determination period), and When the sudden signal inversion set is between the first signal inversion timing and the second inversion timing, the sudden signal inversion set is ignored and the increase/decrease of the fuel amount H is reversed. control to prevent
  • the abrupt signal inversion set K1a is a set of rich/lean state inversions at timing U1a and rich/lean state inversions at timing U1b after timing U1a.
  • the abrupt signal inversion set K1b is a set of rich/lean state inversions at timing U1c and rich/lean state inversions at timing U1d after timing U1c.
  • the length X1a of the sudden signal inversion group K1a and the length X1b of the sudden signal inversion group K1b are longer than the inversion determination period R2.
  • the abrupt signal inversion set K1a and K1b falls between the signal inversion timing T1a and the signal inversion timing T2a. Both the timing U1a and the timing U1b are within the signal invalid period M1.
  • the timing U1c is within the signal invalid period M1, and the timing U1b is after the signal invalid period M1.
  • the abrupt signal inversion set K2a is a set of rich/lean state inversions at timing U2a and rich/lean state inversions at timing U2b after timing U2a.
  • the abrupt signal inversion set K2b is a set of rich/lean state inversions at timing U2c and rich/lean state inversions at timing U2d after timing U2c.
  • the length X2a of the abrupt signal inversion group K2a and the length X2b of the abrupt signal inversion group K2b are longer than the inversion determination period R1.
  • the abrupt signal inversion set K2a and K2b falls between the signal inversion timing T2a and the signal inversion timing T3a.
  • Both the timing U2a and the timing U2b are within the signal invalid period M2.
  • the timing U2c is within the signal invalid period M1, and the timing U2b is after the signal invalid period M1.
  • the catalyst deterioration diagnosis device 80 controls the fuel amount H by ignoring the sudden signal inversion group K2a and K2b when the sudden signal inversion group K2a or the sudden signal inversion group K2b occurs during the signal invalid period M2.
  • the fuel amount H no reversal of the increase/decrease of
  • the first embodiment by providing the signal invalid periods M1 and M2, even if the sudden signal inversion groups K1a, K1b, K2a, and K2b occur during the signal invalid periods M1 and M2, the sudden signal inversion group K1a , K1b, K2a, and K2b do not occur, it is possible to suppress the interval between the increase/decrease reversal of the fuel amount H from becoming shorter. As a result, many opportunities for diagnosing deterioration of the catalyst 53 can be secured.
  • the inversion determination periods R1 and R2 are lengthened so that the abrupt signal inversion group K1a, It is conceivable to prevent the increase/decrease of the fuel amount H from being reversed based on the abrupt signal inversion set K1a, K1b, K2a, and K2b when K1b, K2a, and K2b occur.
  • the reversal determination periods R1 and R2 are made too long, even if normal reversal occurs in the output signal of the upstream oxygen concentration sensor 76 (reversal at the signal reversal timings T1a, T2a, T3a, T4a, and T5a), The increase/decrease of the fuel amount H may not be reversed.
  • the signal invalid periods M1 and M2 are provided to reverse the increase/decrease of the fuel amount H based on the abrupt signal inversion sets K1a, K1b, K2a, and K2b.
  • the signal inversion interval is lengthened.
  • the lengths of the signal invalid periods M1 and M2 hardly affect the length of the signal inversion interval. Therefore, it is not necessary to lengthen the catalyst deterioration diagnosis interval (signal inversion interval) in order to provide the signal invalid periods M1 and M2. Therefore, compared with Comparative Example 2, more opportunities for diagnosing deterioration of the catalyst 53 can be secured.
  • the degree of freedom in setting the length of the catalyst deterioration diagnosis interval (signal inversion interval) is higher than in the second comparative example.
  • the additional time Q1 when the engine 20 is operated such that the signal inversion intervals are equal to the catalyst deterioration diagnosis intervals W1 and W2 may be greater than 0 as shown in FIG. 1, or may be 0.
  • the increase/decrease of the fuel amount H is reversed at timings T1c, T3c, and T5c after the sum of the reversal determination period R1 and the additional time Q1 (R1+Q1) has elapsed from the signal reversal timings T1a, T3a, and T5a.
  • the additional time Q2 when the engine 20 is operated such that the signal inversion intervals are equal to the catalyst deterioration diagnosis intervals W1 and W2 may be greater than 0 as shown in FIG. 1, or may be 0.
  • the increase/decrease of the fuel amount H is reversed at timings T2c and T4c after a time (R2+Q2) obtained by adding the reversal determination period R2 and the additional time Q2 from the signal reversal timings T2a and T4a.
  • the start timing of the signal invalid periods M1 and M2 may be the timing after the second inversion determination period has elapsed from the first signal inversion timing.
  • the inversion determination period R1 is the second inversion determination period.
  • the start timing of the signal invalid interval M1 may be timings T1b, T3b, and T5b when the inversion determination period R1 has passed from the signal inversion timings T1a, T3a, and T5a.
  • the first signal inversion timings are the signal inversion timings T2a and T4a in FIG.
  • the inversion determination period R2 is the second inversion determination period of the present invention.
  • the start timing of the signal invalid interval M2 may be timings T2b and T4b when the inversion determination period R2 has passed from the signal inversion timings T2a and T4a.
  • the start timing of the signal invalid periods M1 and M2 may be the timing between the second signal inversion timing and the timing when the second inversion determination period has elapsed from the first signal inversion timing.
  • Comparative Example 1 compared with the first embodiment will be described with reference to FIGS. 2(a) to 2(c).
  • the signal invalid periods M1 and M2 are not provided between the first signal inversion timing and the second signal inversion timing. Other points are the same as the first embodiment.
  • the signal invalid period M1 is provided, as described above, even if the abrupt signal inversion pairs K1a and K1b having the lengths X1a and X1b longer than the inversion determination period R2 are generated, the abrupt Signal inversion set K1a, K1b is ignored.
  • the increase/decrease of the fuel amount H is not reversed at the timing when the time (R1+Q1) has passed from the timing U2a. Further, the increase/decrease of the fuel amount H is not reversed at the timing when the time (R1+Q1) has passed from the timing U2c.
  • Comparative Example 1 in which the signal invalid period M2 is not provided, if a sudden signal inversion set K2a having a length X2a longer than the inversion determination period R1 is generated, it is indicated by a broken line in FIG. 2(b). Thus, the increase/decrease of the fuel amount H is reversed at the timing after the time (R1+Q1) has passed from the timing U2a.
  • Comparative Example 2 to be compared with the first embodiment will be described with reference to FIGS.
  • the signal invalid periods M1 and M2 are not provided between the first signal inversion timing and the second signal inversion timing.
  • a reversal determination period R1a longer than the reversal determination period R1 is set instead of the reversal determination period R1 of the first embodiment, and a reversal determination period R2 is set instead of the reversal determination period R2 of the first embodiment.
  • a longer reversal determination period R2a is set.
  • Other points are the same as the first embodiment.
  • the signal inversion interval of Comparative Example 2 is longer than the signal inversion interval of the first embodiment.
  • the output signal of the upstream oxygen concentration sensor 76 is switched to the lean state (for example, signal reversal timings T1a1 and T3a1 in FIG. (timings T1b1, T3b1), it is decided to reverse the state of decreasing the fuel quantity H to the state of increasing it.
  • timings for example, timings T1c1 and T3c1 in FIGS.
  • the inversion determination period R1a is longer than the lengths X1a and X1b (see FIG. 1) of the abrupt signal inversion pairs K1a and K1b described in the first embodiment.
  • the inversion determination period R2a is longer than the lengths X2a and X2b (see FIG. 1) of the abrupt signal inversion pairs K2a and K2b described in the first embodiment.
  • Comparative Example 2 when a sudden signal inversion set having a length longer than the lengths X1a and X1b and shorter than the inversion determination period R1a occurs, the fuel amount H is increased/decreased based on this sudden signal inversion set. cannot be reversed. However, in the case of Comparative Example 2, since the inversion determination periods R1a and R2a are long, the period from the signal inversion timings T1a1 and T3a1 until the inversion determination period R1a elapses and from the signal inversion timings T2a1 and T2a1 to the inversion determination period R2a. There is a high possibility that an abrupt signal inversion group will occur during the period until .
  • the increase/decrease of the fuel amount H is not reversed based on the fact that the output signal of the upstream oxygen concentration sensor 76 is switched to the lean state at the signal reversal timing T1a1.
  • the interval between the increase/decrease reversal of the fuel amount H becomes longer than the catalyst deterioration diagnosis interval.
  • a reversal determination period R2a as indicated by the dashed line in FIG.
  • the increase/decrease of the fuel amount H is not reversed at timing T2c1. That is, the increase/decrease of the fuel amount H is not reversed based on the fact that the output signal of the upstream oxygen concentration sensor 76 is switched to the rich state at the signal reversal timing T2a1. As a result, the interval between the increase/decrease reversal of the fuel amount H becomes longer than the deterioration diagnosis interval.
  • the straddle-type vehicle 1 includes an engine unit 11 and a catalyst deterioration diagnostic device 80 .
  • the engine unit 11 includes an engine 20 , an exhaust passage portion 51 , a catalyst 53 , an upstream oxygen concentration sensor 76 and a downstream oxygen concentration sensor 77 .
  • the cooling system of the engine 20 is a natural air cooling system in FIG. 4, other cooling systems may be used.
  • the engine 20 is a four-stroke engine in FIG. 4, it may be a two-stroke engine.
  • the position of the catalyst 53 in the exhaust passage portion 51 is not limited to the position shown in FIG.
  • the catalyst deterioration diagnostic device 80 of the second embodiment is, for example, an ECU (Electronic Control Unit).
  • the ECU controls the engine unit 11 .
  • the ECU may perform control of the straddle-type vehicle 1 other than the control of the engine unit 11 .
  • Straddle-type vehicles generally have a wider range of engine rotation speeds than automobiles.
  • the length of the sudden signal inversion group tends to be long. Therefore, in the second embodiment, when the catalyst deterioration diagnosis device 80 mounted on the straddle-type vehicle 1 diagnoses the deterioration of the catalyst 53, the signal is detected between the first signal inversion timing and the second signal inversion timing. Set an invalid period.
  • diagnosing deterioration of the catalyst 53 in the straddle-type vehicle 1 in which the length of the sudden signal inversion group tends to be long it is possible to secure many opportunities for diagnosing deterioration of the catalyst 53 .
  • the engine unit 11 controlled by the catalyst deterioration diagnosis device 80 of the third embodiment of the invention will be described with reference to FIG.
  • the third embodiment has the configuration of the first embodiment.
  • the third embodiment may have the configuration of the second embodiment.
  • the engine unit 11 has an engine 20, an intake unit 40, and an exhaust unit 50.
  • the engine 20 in FIG. 5 is a four-stroke engine.
  • the engine 20 includes a crankcase 21, a cylinder body 22, and a cylinder head 23.
  • the crankcase 21 accommodates the crankshaft 26 and the like.
  • An engine rotation speed sensor 71 is provided in the crankcase 21 .
  • the engine rotation speed sensor 71 detects the rotation speed of the crankshaft 26, that is, the engine rotation speed.
  • the engine speed is the number of revolutions of the crankshaft 26 per unit time.
  • At least one cylinder hole 22a is formed in the cylinder body 22.
  • a piston 28 is slidably accommodated in each of the at least one cylinder hole 22a.
  • Piston 28 is connected to crankshaft 26 via a connecting rod 29 .
  • a combustion chamber 30 is formed by the cylinder head 23, the cylinder hole 22a and the piston 28.
  • Engine 20 has at least one combustion chamber 30 .
  • a tip portion of a spark plug 31 is arranged in each of the at least one combustion chambers 30 .
  • the tip of the spark plug 31 generates spark discharge. This spark discharge ignites the air-fuel mixture in the combustion chamber 30 .
  • the ignition plug 31 is connected to the ignition coil 32 .
  • the ignition coil 32 stores electric power for generating spark discharge of the ignition plug 31 .
  • One or two intake ports 33 and one or two exhaust ports 34 are formed in the combustion chamber 30 .
  • the intake port 33 is opened and closed by an intake valve 35 .
  • the exhaust port 34 is opened and closed by an exhaust valve 36 .
  • the intake valve 35 and the exhaust valve 36 are driven to open and close by a valve train (not shown) housed in the cylinder head 23 .
  • the valve train operates in conjunction with the crankshaft 26 .
  • the engine unit 11 has an intake passage portion 41 that connects the intake port 33 and an air intake port 41c facing the atmosphere.
  • the intake passage portion 41 is connected to all the combustion chambers 30 of the engine 20 .
  • the air sucked from the air intake port 41 c flows through the intake passage portion 41 toward the intake port 33 .
  • a portion of the intake passage portion 41 is formed in the engine 20 , and the remaining portion of the intake passage portion 41 is formed in the intake unit 40 .
  • the intake unit 40 has an intake pipe connected to the engine 20 .
  • intake unit 40 has at least one injector 42 and at least one throttle valve 45 .
  • the engine unit 11 has an exhaust passage portion 51 that connects the exhaust port 34 and the atmosphere discharge port 64a facing the atmosphere.
  • the exhaust passage portion 51 is connected to all the combustion chambers 30 of the engine 20 . Exhaust gas generated in the combustion chamber 30 is discharged to the exhaust passage portion 51 through the exhaust port 34 . Exhaust gas flows through the exhaust passage portion 51 toward the atmosphere discharge port 64a.
  • a portion of the exhaust passage portion 51 is formed in the engine 20 , and the remaining portion of the exhaust passage portion 51 is formed in the exhaust unit 50 .
  • the exhaust unit 50 has an exhaust pipe 52 connected to the engine 20 . Furthermore, the exhaust unit 50 has a catalyst 53 and a muffler 54 .
  • the muffler 54 is a device that reduces noise caused by exhaust gas.
  • a muffler 54 is included in the exhaust passage portion 51 .
  • An upstream oxygen concentration sensor 76 and a downstream oxygen concentration sensor 77 are provided in the exhaust pipe 52 .
  • the upstream oxygen concentration sensor 76 may be provided on the engine 20 .
  • a downstream oxygen concentration sensor 77 may be provided in the muffler 54 .
  • one catalyst 53 may be provided for the plural fuel chambers 30 , one catalyst 53 may be provided for each fuel chamber 30 , or the plural fuel chambers 30 may be provided for each fuel chamber 30 .
  • One catalyst 53 may be provided for two or more of the fuel chambers 30 .
  • the upstream oxygen concentration sensor 76 may be provided for each catalyst 53 or may be provided for any one of the plurality of catalysts 53 .
  • the downstream oxygen concentration sensor 77 may be provided for each catalyst 53 , may be provided for any one of the plurality of catalysts 53 , or may be provided for the plurality of catalysts 53 .
  • the engine unit 11 may have sub-catalysts arranged upstream or downstream of any of the catalysts 53 apart from the at least one catalyst 53 .
  • the injector 42 is arranged in the intake passage portion 41 .
  • the injector 42 injects fuel into the air inside the intake passage portion 41 .
  • fuel is supplied to the combustion chamber 30 through the intake passage portion 41 .
  • An injector 42 may be provided to inject fuel directly into the combustion chamber 30 .
  • One or two injectors 42 are provided for one combustion chamber 30 .
  • the injector 42 is connected to the fuel tank 10 via a fuel hose 43 .
  • a fuel pump 44 is arranged inside the fuel tank 10 .
  • the fuel pump 44 pumps the fuel in the fuel tank 10 to the fuel hose 43 .
  • fuel supply device 46 has injector 42 and fuel pump 44 .
  • the throttle valve 45 is provided in the intake passage portion 41 .
  • the throttle valve 45 is arranged upstream of the injector 42 .
  • One throttle valve 45 is provided for one combustion chamber 30 .
  • the throttle valve 45 is connected to an accelerator grip (not shown) via a throttle wire.
  • the degree of opening of the throttle valve 45 is changed by the rider rotating the accelerator grip.
  • the engine unit 11 has a throttle opening sensor (throttle position sensor) 73 that detects the opening of the throttle valve 45 .
  • the opening degree of the throttle valve 45 will be referred to as the throttle opening degree.
  • the throttle opening sensor 73 detects the position of the throttle valve 45 and outputs a signal representing the throttle opening.
  • the throttle valve 45 may be an electronic throttle valve that is electronically controlled to open and close. In this case, the throttle opening sensor 73 may output a signal representing the throttle opening based on the electronic control signal.
  • the catalyst deterioration diagnosis device 80 is connected to various sensors such as an engine rotation speed sensor 71, a throttle opening sensor 73, an upstream oxygen concentration sensor 76, a downstream oxygen concentration sensor 77, and the like. Signals from various sensors are input to the catalyst deterioration diagnosis device 80 .
  • the catalyst deterioration diagnostic device 80 is connected to the ignition coil 32, the injector 42, the fuel pump 44, and the like.
  • the catalyst deterioration diagnosis device 80 performs fuel supply amount control and ignition timing control. The above control of the fuel amount H is included in the fuel supply amount control.
  • the catalyst deterioration diagnosis device 80 controls the injector 42 and the fuel pump 44 in controlling the fuel supply amount.
  • the catalyst deterioration diagnosis device 80 controls the fuel amount H supplied to at least one combustion chamber 30 by controlling the fuel injection time of the injector 42 .
  • the catalyst deterioration diagnosis device 80 controls the ignition coil 32 in ignition timing control.
  • FIG. 6(a), (b) and 7. A fourth embodiment of the present invention will be described with reference to FIGS. 6(a), (b) and 7.
  • FIG. The fourth embodiment has the configuration of the first embodiment.
  • the fourth embodiment may have at least one configuration of the second and third embodiments.
  • the catalyst deterioration diagnosis device 80 performs processing according to the flow shown in FIG. 6(a). Control of the fuel amount H when the flow of FIG. 6(a) is started is normal fuel amount H control. When the control of the fuel amount H is normal control of the fuel amount H, and when the processing of steps S11 to S17 described later is being performed, the catalyst deterioration diagnosis device 80 detects the output signal of the upstream oxygen concentration sensor 76. The fuel amount H is controlled based on.
  • the fuel amount H decreases by ⁇ Sb.
  • the fuel amount H gradually decreases by ⁇ B at each time interval ⁇ b.
  • ⁇ Sb may be the same as ⁇ Sa, or may be different from ⁇ Sa.
  • the time interval ⁇ b may be the same as the time interval ⁇ a or may be different from the time interval ⁇ a.
  • ⁇ B may be the same as ⁇ A or may be different from ⁇ A.
  • Time Wsb may be the same as time Wsa, or may be different from time Wsa.
  • the catalyst deterioration diagnosis device 80 determines whether or not the conditions for catalyst deterioration diagnosis are satisfied (step S11).
  • the catalyst deterioration diagnosis conditions include a first condition that should be satisfied before the deterioration diagnosis of the catalyst 53 and a second condition that must be satisfied both before the deterioration diagnosis of the catalyst 53 and during the deterioration diagnosis of the catalyst 53 .
  • the first condition includes, for example, the condition that a certain period of time has elapsed since the engine 20 was started. Further, the first condition includes, for example, a condition that the reversal cycle of increase/decrease of the fuel amount is within a predetermined range. The first condition may include at least one of these conditions.
  • the second condition includes, for example, the condition that both the upstream oxygen concentration sensor 76 and the downstream oxygen concentration sensor 77 are activated.
  • the second condition includes, for example, the condition that the catalyst 53 is activated.
  • the catalyst deterioration diagnostic device 80 determines whether or not the oxygen concentration sensors 76 and 77 or the catalyst 53 is activated from, for example, the elapsed time after the engine is started and/or the cumulative engine speed, the engine temperature, the outside air temperature, and the like. may Further, the second condition includes, for example, the condition that the rotational speed of the engine 20 and the load of the engine 20 are within ranges suitable for the degradation diagnosis of the catalyst 53 .
  • the second condition includes, for example, a condition that both the amount of change in the amount of air supplied to the engine 20 and the amount of change in air pressure are equal to or less than a threshold. Note that the second condition may include at least one of these conditions. Further, when the catalyst deterioration diagnosis device 80 executes the processes of steps S13 to S17 thereafter, it determines whether or not the second condition is satisfied in parallel with these processes. When the catalyst deterioration diagnosis device 80 determines that the catalyst deterioration diagnosis condition is not satisfied (step S11: NO), the control of the fuel amount H is maintained at the normal fuel amount H control.
  • the catalyst deterioration diagnosis device 80 determines whether or not the previous deterioration diagnosis of the catalyst 53 was terminated halfway (step S12). For example, when the engine 20 is stopped during the deterioration diagnosis of the catalyst 53, the catalyst deterioration diagnosis device 80 ends the deterioration diagnosis of the catalyst 53 in the middle. Further, the catalyst deterioration diagnosis device 80 ends the deterioration diagnosis of the catalyst 53 halfway, for example, when the control of the fuel amount H based on the output signal of the upstream oxygen concentration sensor 76 is no longer performed.
  • the catalyst deterioration diagnosis device 80 ends the deterioration diagnosis of the catalyst 53 in the middle, for example, when the second condition is no longer satisfied during the deterioration diagnosis of the catalyst 53 .
  • the catalyst deterioration diagnosis device 80 may not be able to operate the engine 20 so that the signal inversion interval is equal to the catalyst deterioration diagnosis interval during the deterioration diagnosis of the catalyst 53, for example. If the reversal period of decrease becomes extremely long, the deterioration diagnosis of the catalyst 53 is terminated halfway. In at least one of these cases, the catalyst deterioration diagnosis device 80 may end the deterioration diagnosis of the catalyst 53 halfway.
  • step S12 If the previous diagnosis of deterioration of the catalyst 53 has not ended halfway (step S12: NO), the catalyst deterioration diagnosis device 80 performs the processes of steps S13 and S14, and then proceeds to step S15. If the previous deterioration diagnosis of the catalyst 53 was terminated halfway (step S12: YES), the catalyst deterioration diagnosis device 80 directly proceeds to step S15. In step S13, the catalyst deterioration diagnosis device 80 changes the control of the fuel amount H from the normal control of the fuel amount H to the control of the fuel amount H for measuring the cycle of reversing the increase/decrease of the fuel amount H. switch.
  • the catalyst deterioration diagnosis device 80 changes, for example, at least one of ⁇ a, ⁇ b, ⁇ A, ⁇ Sa, ⁇ B, ⁇ Sb, Wsa, and Wsb shown in FIG. Switch to control of the fuel amount H for measuring the period of reversal of decrease. Note that when the control of the fuel amount H is switched in step S13 and step S15 described later, the control of the intake air amount is not changed. Therefore, even if the control of the fuel amount H is switched in step S13 and step S15, which will be described later, the rotation speed of the engine 20 does not change significantly.
  • the time Wsa and the time Wsb are, for example, the reversal determination time R1 and the reversal determination time R2.
  • the catalyst deterioration diagnosis device 80 measures the cycle of reversal of the increase/decrease of the fuel amount H.
  • FIG. in step S15 the catalyst deterioration diagnosis device 80 changes the control of the fuel amount H from the normal control of the fuel amount H or the control of the fuel amount H for measuring the cycle of reversal of the increase/decrease of the fuel amount H to the catalyst Switching to control of the fuel amount H for deterioration diagnosis of 53 .
  • the catalyst deterioration diagnosis device 80 changes, for example, the times Wsa and Wsb based on the period of reversal of the increase/decrease of the fuel amount H measured in step S14, and the signal inversion interval for the engine 20 becomes the catalyst deterioration diagnosis interval. drive like this. More specifically, for example, the time Wsa is changed to a time obtained by adding an additional time Q1 greater than 0 to the reversal determination time R1, and the time Wsb is changed to a time obtained by adding an additional time Q2 greater than 0 to the reversal determination time R2. changed in time.
  • the catalyst deterioration diagnosis device 80 determines whether the increase/decrease of the fuel amount H measured in step S14 at the time of the previous deterioration diagnosis of the catalyst 53 is determined. For example, the times Wsa and Wsb are changed based on the reversal period, and the control of the fuel amount H is such that the signal reversal interval becomes the catalyst deterioration diagnosis interval. Further, in step S15, the catalyst deterioration diagnosis device 80 provides a signal invalid period between the first signal inversion timing and the second signal inversion timing, as described in the first embodiment.
  • the catalyst deterioration diagnosis device 80 diagnoses the deterioration of the catalyst 53 (step S16). After completing the deterioration diagnosis of the catalyst 53 in step S16, the catalyst deterioration diagnosis device 80 switches the fuel amount H control to normal fuel amount H control (step S17), and returns to step S11.
  • FIG. 6(b) is a diagram showing an example of changes in the fuel amount H when the process is performed along the flow of FIG. 6(a). In this example, the catalyst deterioration diagnosis device 80 switches control of the fuel amount H to control of the fuel amount H for measuring the cycle of reversal of increase/decrease of the fuel amount H at the timing Ta.
  • the catalyst deterioration diagnosis device 80 switches the control of the fuel amount H to the control of the fuel amount H for diagnosing the deterioration of the catalyst 53 at the timing Tb after the timing Ta. Further, the catalyst deterioration diagnosis device 80 switches the control of the fuel amount H to the normal control of the fuel amount H at the timing Tc after the timing Tb.
  • the signal inversion interval is changed at timing Ta, timing Tb, and timing Tc.
  • a period similar to the signal invalid period may be provided when the control of the fuel amount H is for measuring the cycle of reversing the increase/decrease of the fuel amount H. That is, when the control of the fuel amount H is the control of the fuel amount H for measuring the cycle of reversing the increase/decrease of the fuel amount H, the period between the first signal inversion timing and the second signal inversion timing may be provided with a period similar to the signal invalid period. Even if a sudden set of signal inversions longer than a predetermined length occurs in the output signal of the upstream oxygen concentration sensor 76 during this provided period, the set of signal inversions is ignored and the fuel amount H is increased/decreased. You may control so that it may not be reversed.
  • the length of the period similar to the signal invalid period provided when controlling the fuel amount H for measuring the cycle of reversing the increase/decrease of the fuel amount H is determined by the control of the fuel amount H. may be the same as or different from the length of the signal invalid period provided when controlling the fuel amount H for diagnosing the deterioration of the catalyst 53 .
  • the control of the fuel amount H is the control of the fuel amount H for measuring the cycle of reversing the increase/decrease of the fuel amount, it is not necessary to provide the signal invalid period. This makes it possible to further simplify the control of the fuel amount when the deterioration diagnosis of the catalyst 53 is not performed.
  • control may be performed so that the signal invalid period is always provided while the engine 20 is running.
  • FIG. The fifth embodiment has the configuration of the first embodiment.
  • the fifth embodiment may have at least one configuration of the second to fourth embodiments.
  • the catalyst deterioration diagnosis device 80 as the control of the fuel amount H, starts the processing along the flow of FIG. is the normal fuel amount H control, this process is continued.
  • the control of the normal fuel amount H in the fifth embodiment is similar to the control of the normal fuel amount H in the fourth embodiment. It differs from both the control of H and the control of the fuel amount H for diagnosing deterioration of the catalyst 53 .
  • the catalyst deterioration diagnosis device 80 controls the fuel amount H based on the output signal of the upstream oxygen concentration sensor 76 .
  • the setting of the signal invalid period is cancelled.
  • a state in which the setting of the signal invalid period is canceled means a state in which no signal invalid period is provided between the first signal inversion timing and the second signal inversion timing.
  • the catalyst deterioration diagnosis device 80 determines whether or not conditions for catalyst deterioration diagnosis are satisfied (step S21).
  • the conditions for diagnosing catalyst deterioration include, for example, a condition that a certain period of time has elapsed since the start of the engine 20 and/or a condition that a certain period of time has elapsed since the previous deterioration diagnosis of the catalyst 53 . If the catalyst deterioration diagnosis condition is not satisfied (step S21: NO), the catalyst deterioration diagnosis device 80 maintains the state in which the setting of the signal invalid period is canceled.
  • the catalyst deterioration diagnosis device 80 determines whether the control of the fuel amount H satisfies a predetermined condition (step S22).
  • the predetermined condition in step S22 is a condition when the engine 20 is operated such that the signal inversion interval is equal to the catalyst deterioration diagnosis interval. Includes conditions for at least one of Wsb. Note that when the control of the fuel amount H satisfies a predetermined condition, the time Wsa and the time Wsb are, for example, the reversal determination time R1 and the reversal determination time R2.
  • the time Wsa is the time obtained by adding the additional time Q1 of 0 to the reversal determination time R1
  • the time Wsb is the time obtained by adding the additional time Q2 of 0 to the reversal determination time R2.
  • the catalyst deterioration diagnosis device 80 provides a signal invalid period between the first signal inversion timing and the second signal inversion timing, as described in the first embodiment. Subsequently, the catalyst deterioration diagnosis device 80 diagnoses deterioration of the catalyst 53 in the same manner as described in the first embodiment (step S24). After completing the deterioration diagnosis of the catalyst 53, the catalyst deterioration diagnosis device 80 cancels the setting of the signal invalid period (step S25), and returns to step S21.
  • the catalyst deterioration diagnosis device 80 performs the processing as described above, so that the signal ineffective period is set to the catalyst deterioration diagnosis interval except when the engine 20 is operated such that the signal inversion interval is the catalyst deterioration diagnosis interval. It is controlled not to set. This makes it possible to simplify the control of the fuel amount H when the deterioration diagnosis of the catalyst 53 is not performed.
  • the signal invalid period is set when the catalyst deterioration diagnosis condition is satisfied and the control of the fuel amount H satisfies the predetermined condition, but it is not limited to this.
  • the signal invalid period is set regardless of whether or not the catalyst deterioration diagnosis condition is met, and the catalyst deterioration diagnosis is performed in the state in which the signal invalid period is set.
  • the deterioration diagnosis of the catalyst may be performed.
  • the catalyst deterioration diagnosis device performs control so that the signal invalid period is not provided except when the engine 20 is operated so that the signal inversion interval becomes the catalyst deterioration diagnosis interval.
  • the sixth embodiment has the configuration of the first embodiment.
  • the sixth embodiment may have at least one configuration of the second to fifth embodiments.
  • the catalyst deterioration diagnosis device 80 performs deterioration diagnosis of the catalyst 53 when the signal inversion interval is a catalyst deterioration diagnosis interval suitable for deterioration diagnosis of the catalyst 53 .
  • the catalyst deterioration diagnosis device 80 controls the signal invalid period to be set to different lengths according to the operating state of the engine 20 .
  • the length that varies depending on the operating state of the engine 20 is, for example, a length that varies depending on the rotational speed of the engine 20 and/or the load of the engine 20 or the like.
  • the catalyst deterioration diagnosis interval is changed according to the operating state of the engine 20 .
  • the catalyst deterioration diagnosis intervals W1 and W2 may be changed by changing the reversal determination periods R1 and R2 according to the operating state of the engine 20 .
  • the operating state of the engine 20 is such that the catalyst deterioration diagnosis interval W1 is W1a and the catalyst deterioration diagnosis interval W2 is W2a, as shown in FIG.
  • the deterioration diagnosis device 80 sets the length of the signal invalid period M1 to N1a, and sets the length of the signal invalid period M2 to N2a.
  • FIG. 9(b) shows a case where the operating state of the engine 20 is different from that in FIG. 9(a).
  • the operating state of the engine 20 is such that the catalyst deterioration diagnosis interval W1 is W1b, which is shorter than W1a, and the catalyst deterioration diagnosis interval W2 is W2b, which is shorter than W2a.
  • the catalyst deterioration diagnosis device 80 sets the length of the signal invalid period M1 to N1b, which is shorter than N1a, and sets the length of the signal invalid period M2 to N2b, which is shorter than N2a.
  • the length of the signal invalid period is set to different lengths according to the catalyst deterioration diagnosis interval that varies depending on the operating state of the engine 20 .
  • the catalyst deterioration diagnosis interval does not necessarily differ between the two cases in which the operating state of the engine 20 differs. Diagnostic intervals may be the same.
  • the length of the signal invalid period may be different or the same depending on the operating condition of the engine 20 .
  • the length of the signal invalid period is varied according to the operating state of the engine 20, but the length of the signal invalid period may always be the same regardless of the operating state of the engine 20.
  • the catalyst deterioration diagnosis device 80 increases/decreases the correction coefficient for determining the correction amount for the basic fuel supply amount based on the signal from the upstream oxygen concentration sensor 76.
  • the fuel amount H may be increased/decreased.
  • the correction coefficient is, for example, a coefficient whose value increases as the amount of fuel H supplied to the combustion chamber 30 increases.

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Abstract

In the present invention, when an engine is being operated so that a signal inversion interval is a catalyst deterioration diagnosis interval, said signal inversion interval being the length of time between a first signal inversion time and a second signal inversion time at which a rich/lean state of an output signal from an upstream oxygen concentration sensor is inverted, a diagnosis of the deterioration of the catalyst is carried out on the basis of an output signal from a downstream oxygen concentration sensor. A signal inactivity interval is provided between the first signal inversion time and the second signal inversion time. When a pair of sudden signal inversions occurs in the signal inactivity interval, the length of the pair of sudden signal inversions is greater than a first inversion determination interval, and the pair of sudden signal inversions falls in an interval between the first signal inversion time and the second signal inversion time, the pair of sudden signal inversions is disregarded and an increase/decrease in an amount of fuel is controlled so as not to be inverted.

Description

触媒劣化診断装置Catalyst deterioration diagnosis device
　この発明は、エンジンから排出された排ガスを浄化する触媒の劣化を診断する触媒劣化診断装置に関する。 This invention relates to a catalyst deterioration diagnostic device that diagnoses deterioration of a catalyst that purifies exhaust gas emitted from an engine.
　従来、エンジンから排出された排ガスを浄化する触媒の劣化を診断する触媒劣化診断装置がある。例えば、特許文献１では、排ガスの流れ方向における触媒の上流および下流に、それぞれ、上流酸素濃度センサおよび下流酸素濃度センサが設けられる。上流酸素濃度センサの出力信号のリッチ／リーン状態が反転したときに、触媒劣化診断装置はリッチ／リーン状態が継続する時間をカウントし、継続時間が所定の遅延時間に達したときに燃焼室に供給される燃料量の増加／減少を反転させるようにエンジンを運転させる。そして、上流酸素濃度センサの出力信号のリッチ／リーン状態に基づいて燃料量の増加／減少の反転が制御されているときの、下流酸素濃度センサの出力信号に基づいて触媒の劣化診断を行う。 Conventionally, there is a catalyst deterioration diagnosis device that diagnoses the deterioration of the catalyst that purifies the exhaust gas emitted from the engine. For example, in Patent Document 1, an upstream oxygen concentration sensor and a downstream oxygen concentration sensor are provided respectively upstream and downstream of the catalyst in the flow direction of the exhaust gas. When the rich/lean state of the output signal of the upstream oxygen concentration sensor is reversed, the catalyst deterioration diagnosis device counts the duration of the rich/lean state, and when the duration reaches a predetermined delay time, Operate the engine to reverse the increase/decrease in the amount of fuel supplied. Deterioration diagnosis of the catalyst is performed based on the output signal of the downstream oxygen concentration sensor when the reversal of the increase/decrease of the fuel amount is controlled based on the rich/lean state of the output signal of the upstream oxygen concentration sensor.
特許第３１８１１１３号公報Japanese Patent No. 3181113
　ここで、エンジンの形態または用途によっては、上流酸素濃度センサの出力信号に、突発的な反転とそれに続く反転の組（以下、「突発的信号反転組」と称する）が発生し、突発的信号反転組における先の反転と後の反転との間隔（以下、「突発的信号反転組の長さ」と称する）が長くなることがある。特許文献１の技術では、上記遅延時間よりも長さの短い突発的信号反転組が発生しても、燃料量の増加と減少が反転されないが、上記遅延時間よりも長さの長い突発的信号反転組が発生した場合には、燃料量の増加と減少が反転されてしまう。その結果、長さの長い突発的信号反転組によって、燃料量の増加と減少が反転される間隔が変化してしまう。
　特許文献１の下流酸素濃度センサの出力信号に基づく触媒の劣化診断は、燃料量の増加と減少の反転の周期が診断に適した周期となっていることを前提とする。そのため、長さの長い突発的信号反転組によって燃料量の増加と減少が反転される間隔が変化してしまうと、触媒の劣化診断が可能となる機会が減少してしまう。
　ここで、特許文献１において上記遅延時間を長くすることによって、長さの長い突発的信号反転組が発生しても燃料量の増加と減少が反転されないようにすることが考えられる。しかしながら、この場合には、上流酸素濃度センサの出力信号に正常な反転が発生しているのか突発的信号反転組が発生しているのかが区別できなくなりやすい。その結果、上流酸素濃度センサの出力信号に正常な反転が生じたときにも燃料量の増加と減少が反転されなくなりやすい。
　上流酸素濃度センサの出力信号に長さの長い突発的信号反転組が発生しても、触媒の劣化診断が可能となる機会が確保されることが望まれている。 Here, depending on the form or application of the engine, a set of abrupt reversals and subsequent reversals (hereinafter referred to as "abrupt signal inversion set") occurs in the output signal of the upstream oxygen concentration sensor, and the abrupt signal The interval between the earlier and later inversions in the set of inversions (hereafter referred to as the "length of the set of abrupt signal inversions") can be long. In the technique of Patent Document 1, even if a sudden signal reversal set shorter than the delay time is generated, the increase and decrease of the fuel amount are not reversed, but a sudden signal longer than the delay time If a reversal set occurs, the increase and decrease of the fuel amount will be reversed. As a result, a long set of abrupt signal inversions will change the interval at which the fuel quantity increase and decrease are reversed.
The catalyst deterioration diagnosis based on the output signal of the downstream oxygen concentration sensor in Patent Document 1 is based on the premise that the cycle of reversing the increase and decrease of the fuel amount is a cycle suitable for diagnosis. Therefore, if the interval at which the increase and decrease of the fuel quantity are reversed changes due to the long sudden signal reversal group, the chances of diagnosing deterioration of the catalyst are reduced.
Here, in Patent Document 1, by lengthening the delay time, it is conceivable to prevent the increase and decrease of the fuel quantity from being reversed even if a long sudden signal inversion group occurs. However, in this case, it is likely to be difficult to distinguish whether a normal reversal has occurred in the output signal of the upstream oxygen concentration sensor or an abrupt signal reversal group has occurred. As a result, even when a normal reversal occurs in the output signal of the upstream oxygen concentration sensor, the increase and decrease in the fuel amount are likely not to be reversed.
It is desired to secure an opportunity to diagnose deterioration of the catalyst even if a long sudden signal inversion group occurs in the output signal of the upstream oxygen concentration sensor.
　本発明は、上流酸素濃度センサの出力信号に長さの長い突発的信号反転組が発生しても、触媒の劣化診断が可能となる機会を確保することができる触媒劣化診断装置を提供することを目的とする。 To provide a catalyst deterioration diagnosis device capable of securing an opportunity for diagnosing deterioration of a catalyst even when a long sudden signal inversion group occurs in an output signal of an upstream oxygen concentration sensor. With the goal.
　エンジンの燃焼室から排出される排ガスの流れ方向において触媒の上流に配置され、混合気の空燃比がリッチとリーンのどちらであるかに応じた信号を出力する上流酸素濃度センサの出力信号のリッチ／リーン状態の反転に基づいて、前記エンジンに供給する燃料量の増加／減少の反転が行われるように前記エンジンを運転させ、
　前記上流酸素濃度センサの出力信号のリッチ／リーン状態が反転する第１信号反転タイミングと、前記第１信号反転タイミングの次に前記上流酸素濃度センサの出力信号のリッチ／リーン状態が反転する第２信号反転タイミングとの間隔を信号反転間隔と定義すると、
　前記信号反転間隔が前記触媒の劣化診断に適した触媒劣化診断間隔となるように前記エンジンが運転されているときに、排ガスの流れ方向において触媒の下流に配置された下流酸素濃度センサの出力信号に応じて前記触媒の劣化診断を行う触媒劣化診断装置であって、
　前記信号反転間隔が前記触媒劣化診断間隔となるように前記エンジンが運転されているときの前記第１信号反転タイミングと前記第２信号反転タイミングとの間の期間に突発的に発生する、前記上流酸素濃度センサの出力信号におけるリッチ／リーン状態の反転とこれに続くリッチ／リーン状態の反転との組を突発的信号反転組と定義し、
　前記突発的信号反転組における先のリッチ／リーン状態の反転と後のリッチ／リーン状態の反転との間隔を、突発的信号反転組の長さと定義し、
　前記信号反転間隔が前記触媒劣化診断間隔となるように前記エンジンが運転されているときの、前記第２信号反転タイミングと、その後前記上流酸素濃度センサの出力信号の前記第２信号反転タイミングでのリッチ／リーン状態の反転に基づいて前記燃料量の増加／減少を反転させることが決定されるタイミングとの間隔を第１反転判定期間と定義したときに、
　前記信号反転間隔が前記触媒劣化診断間隔となるように前記エンジンが運転されているときの前記第１信号反転タイミングと前記第２信号反転タイミングとの間の期間に信号無効期間を設け、前記信号無効期間に前記突発的信号反転組が発生し、当該突発的信号反転組の長さが前記第１反転判定期間よりも長く、かつ、当該突発的信号反転組が前記第１信号反転タイミングと前記第２信号反転タイミングとの間の期間内に収まる場合に、当該突発的信号反転組を無視して燃料量の増加／減少を反転させないように制御する。 Rich in the output signal of an upstream oxygen concentration sensor that is arranged upstream of the catalyst in the flow direction of the exhaust gas discharged from the combustion chamber of the engine and outputs a signal according to whether the air-fuel ratio of the air-fuel mixture is rich or lean. / operating the engine such that an increase/decrease reversal of the amount of fuel supplied to the engine is performed based on the reversal of the lean condition;
a first signal inversion timing at which the rich/lean state of the output signal of the upstream oxygen concentration sensor is inverted; and a second signal inversion timing at which the rich/lean state of the output signal of the upstream oxygen concentration sensor is inverted following the first signal inversion timing. If the interval from the signal inversion timing is defined as the signal inversion interval,
An output signal of a downstream oxygen concentration sensor arranged downstream of the catalyst in the exhaust gas flow direction when the engine is operated such that the signal inversion interval is a catalyst deterioration diagnosis interval suitable for deterioration diagnosis of the catalyst. A catalyst deterioration diagnosis device for diagnosing deterioration of the catalyst according to
The upstream which suddenly occurs during the period between the first signal inversion timing and the second signal inversion timing when the engine is operated such that the signal inversion interval is equal to the catalyst deterioration diagnosis interval. defining a set of rich/lean state inversions followed by rich/lean state inversions in the output signal of the oxygen concentration sensor as an abrupt signal inversion pair;
defining an interval between an earlier rich/lean state reversal and a later rich/lean state reversal in the set of abrupt signal inversions as a set of abrupt signal inversions;
When the engine is operated such that the signal inversion interval is equal to the catalyst deterioration diagnosis interval, the second signal inversion timing and the output signal of the upstream oxygen concentration sensor at the second signal inversion timing after that. When the first reversal determination period is defined as the interval from the timing at which it is determined to reverse the increase/decrease of the fuel amount based on the reversal of the rich/lean state,
A signal invalid period is provided in a period between the first signal inversion timing and the second signal inversion timing when the engine is operated such that the signal inversion interval is equal to the catalyst deterioration diagnosis interval, and the signal The abrupt signal inversion group occurs during the invalid period, the length of the abrupt signal inversion group is longer than the first inversion determination period, and the abrupt signal inversion group is the first signal inversion timing and the abrupt signal inversion group. If it falls within the period between the second signal inversion timing, the sudden signal inversion group is ignored and the increase/decrease of the fuel amount is controlled so as not to be reversed.
　この構成によると、触媒劣化診断装置は、上流酸素濃度センサの出力信号のリッチ／リーン状態の反転に基づいてエンジンに供給する燃料量の増加／減少の反転が行われるようにエンジンを運転させる。また、触媒劣化診断装置は、信号反転間隔が触媒劣化診断間隔となるようにエンジンが運転されているときに下流酸素濃度センサの出力信号に応じて触媒の劣化診断を行う。また、触媒劣化診断装置は、信号反転間隔が触媒劣化診断間隔となるようにエンジンが運転されているときに、第１信号反転タイミングと第２信号反転タイミングとの間に信号無効期間を設ける。そして、信号無効期間に、上流酸素濃度センサの出力信号に突発的信号反転組が発生し、当該突発的信号反転組の長さが第１反転判定期間よりも長く、かつ、当該突発的信号反転組が前記第１信号反転タイミングと前記第２信号反転タイミングとの間の期間内に収まる場合に、当該突発的信号反転組を無視して燃料量の増加／減少を反転させない。
　ここで、信号無効期間を設けないと、上述したような突発的信号反転組が発生したときに、当該突発的信号反転組に基づく燃料量の増加／減少が反転される。その結果、燃料量の増加／減少の反転の間隔が触媒劣化診断間隔よりも短くなって、触媒の劣化診断を行うことができなくなる。すなわち、触媒の劣化診断が可能となる機会が少なくなる。
　また、信号無効期間を設ける代わりに、第１反転判定期間を長くすることによっても、上述したような突発的信号反転組に基づいた燃料量の増加／減少の反転が生じないにようすることができる。しかしながら、第１反転判定期間を長くしすぎると、上流酸素濃度センサの出力信号に正常な反転が生じたときにも燃料量の増加／減少が反転されなくなる可能性が高くなる。この場合、燃料量の増加／減少の反転の間隔が触媒劣化診断間隔よりも長くなって、触媒の劣化診断を行うことができなくなる。すなわち、触媒の劣化診断が可能となる機会が少なくなる。
　これに対して、この構成では、上述したように、第１信号反転タイミングと第２信号反転タイミングとの間に信号無効期間を設けることによって、突発的信号反転組を無視して燃料量の増加／減少を反転させないようにしている。これにより、長さの長い突発的信号反転組に基づいて燃料量の増加／減少を反転しないようにしつつも、上流酸素濃度センサの出力信号に正常な反転が発生したときには確実に燃料量の増加／減少を反転させることができる。その結果、燃料量の増加／減少の反転の間隔が触媒劣化診断間隔よりも短くなったり長くなったりすることを抑制でき、触媒の劣化診断が可能となる機会を確保することができる。 According to this configuration, the catalyst deterioration diagnosis device operates the engine so that the increase/decrease of the amount of fuel supplied to the engine is reversed based on the reversal of the rich/lean state of the output signal of the upstream oxygen concentration sensor. Further, the catalyst deterioration diagnosis device diagnoses deterioration of the catalyst according to the output signal of the downstream oxygen concentration sensor when the engine is operated such that the signal inversion interval is equal to the catalyst deterioration diagnosis interval. Further, the catalyst deterioration diagnosis device provides a signal invalid period between the first signal inversion timing and the second signal inversion timing when the engine is operated such that the signal inversion interval is the catalyst deterioration diagnosis interval. Then, during the signal invalid period, a sudden signal inversion group occurs in the output signal of the upstream oxygen concentration sensor, the length of the sudden signal inversion group is longer than the first inversion determination period, and the sudden signal inversion group When the set falls within the period between the first signal inversion timing and the second signal inversion timing, the sudden signal inversion set is ignored and the increase/decrease of the fuel quantity is not reversed.
Here, if the signal invalid period is not provided, the increase/decrease of the fuel quantity based on the sudden signal reversal group is reversed when the sudden signal reversal group as described above occurs. As a result, the interval between the increase/decrease reversal of the fuel amount becomes shorter than the catalyst deterioration diagnosis interval, and deterioration diagnosis of the catalyst cannot be performed. That is, the chances of diagnosing deterioration of the catalyst are reduced.
Also, by lengthening the first reversal determination period instead of providing the signal invalid period, it is possible to prevent the reversal of the increase/decrease of the fuel amount based on the sudden signal reversal group as described above from occurring. can. However, if the first reversal determination period is made too long, there is a high possibility that the increase/decrease of the fuel amount will not be reversed even when the output signal of the upstream oxygen concentration sensor normally reverses. In this case, the interval between the increase/decrease reversal of the fuel amount becomes longer than the catalyst deterioration diagnosis interval, and deterioration diagnosis of the catalyst cannot be performed. That is, the chances of diagnosing deterioration of the catalyst are reduced.
On the other hand, in this configuration, as described above, the signal invalid period is provided between the first signal inversion timing and the second signal inversion timing, thereby ignoring the sudden signal inversion group and increasing the fuel amount. / Decrease is not reversed. This ensures that the increase/decrease in fuel quantity is not reversed based on a long set of abrupt signal reversals, but that the fuel quantity increases when a normal reversal occurs in the output signal of the upstream oxygen concentration sensor. /decrease can be reversed. As a result, it is possible to prevent the interval between the increase/decrease reversal of the fuel amount from becoming shorter or longer than the catalyst deterioration diagnosis interval, thereby securing an opportunity to enable deterioration diagnosis of the catalyst.
　本発明の一実施形態の触媒劣化診断装置は、以下の構成を有してもよい。
　前記信号反転間隔が前記触媒劣化診断間隔となるように前記エンジンが運転されているときの、前記第１信号反転タイミングと、その後前記上流酸素濃度センサの出力信号の前記第１信号反転タイミングでのリッチ／リーン状態の反転に基づいて前記燃料量の増加／減少を反転させることが決定されるタイミングとの間隔を第２反転判定期間と定義したときに、
　前記信号無効期間の開始タイミングを、前記第１信号反転タイミングの後、前記第２反転判定期間が経過したタイミングとなるように制御する。 A catalyst deterioration diagnosis device according to an embodiment of the present invention may have the following configuration.
When the engine is operated such that the signal inversion interval is equal to the catalyst deterioration diagnosis interval, the first signal inversion timing and then the output signal of the upstream oxygen concentration sensor at the first signal inversion timing. When the second reversal determination period is defined as the interval from the timing at which it is determined to reverse the increase/decrease of the fuel amount based on the reversal of the rich/lean state,
The start timing of the signal invalid period is controlled so as to be the timing when the second inversion determination period has elapsed after the first signal inversion timing.
　この構成によると、信号無効期間の開始タイミングを、第１信号反転タイミングの後、第２反転判定期間が経過したタイミングとなるように制御する。
　ここで、この構成と異なり、信号無効期間の開始タイミングが、第１信号反転タイミングの後、第２反転判定期間が経過したタイミングよりも後のタイミングである場合を考える。この場合、第１信号反転タイミングの後、第２反転判定期間が経過したタイミングから信号無効期間の開始タイミングまでの期間に発生した突発的信号反転組に基づいて、燃料量の増加／減少が反転されてしまうことがある。その結果、燃料量の増加と減少が反転される間隔が触媒劣化診断間隔よりも短くなって、触媒の劣化診断が可能となる機会が減少してしまう。
　以上のことから、この構成では、信号無効期間の開始タイミングを、第１信号反転タイミングの後、第２反転判定期間が経過したタイミングよりも後のタイミングとする場合よりも、触媒の劣化診断が可能となる機会を多く確保することができる。 According to this configuration, the start timing of the signal invalid period is controlled to be the timing after the first signal inversion timing and the second inversion determination period.
Here, unlike this configuration, consider a case where the start timing of the signal invalid period is after the timing at which the second inversion determination period has passed after the first signal inversion timing. In this case, after the first signal inversion timing, the increase/decrease of the fuel amount is reversed based on the sudden signal inversion group that occurs during the period from the timing at which the second inversion determination period has elapsed to the start timing of the signal invalid period. There are times when it is done. As a result, the interval at which the increase and decrease of the fuel amount are reversed becomes shorter than the catalyst deterioration diagnosis interval, and the chances of enabling deterioration diagnosis of the catalyst decrease.
From the above, in this configuration, deterioration diagnosis of the catalyst can be performed more effectively than in the case where the start timing of the signal invalid period is after the timing at which the second inversion determination period has passed after the first signal inversion timing. You can secure as many opportunities as possible.
　本発明の一実施形態の触媒劣化診断装置は、以下の構成を有してもよい。
　前記信号反転間隔が前記触媒劣化診断間隔となるように前記エンジンが運転されているとき以外には、前記信号無効期間を設けないように制御する。 A catalyst deterioration diagnosis device according to an embodiment of the present invention may have the following configuration.
Control is performed so that the signal invalid period is not provided except when the engine is operated such that the signal inversion interval is equal to the catalyst deterioration diagnosis interval.
　この構成によると、信号反転間隔が触媒劣化診断間隔となるようにエンジンが運転されているとき以外、すなわち、触媒劣化診断を行っていないときに、信号無効期間を設ける制御を行わない。したがって、触媒劣化診断を行っていないときの燃料量の増加／減少の反転の制御を簡単にすることができる。 According to this configuration, control to provide a signal invalid period is not performed except when the engine is operated such that the signal inversion interval is equal to the catalyst deterioration diagnosis interval, that is, when the catalyst deterioration diagnosis is not performed. Therefore, it is possible to simplify the control for reversing the increase/decrease of the fuel amount when the catalyst deterioration diagnosis is not performed.
　本発明の一実施形態の触媒劣化診断装置は、以下の構成を有してもよい。
　前記信号無効期間を、前記エンジンの運転状態に応じて異なった長さに設定するように制御する。 A catalyst deterioration diagnosis device according to an embodiment of the present invention may have the following configuration.
The signal invalid period is controlled to be set to different lengths according to the operating conditions of the engine.
　この構成によると、エンジンの運転状態に合わせて信号無効期間を適切な期間とすることができる。 According to this configuration, the signal invalid period can be set to an appropriate period according to the operating state of the engine.
　本発明および実施の形態において、エンジンの燃料は、ガソリン燃料、アルコール燃料、ガソリンとアルコールの混合燃料、または、軽油のいずれかでもよい。エンジンの形式は、４ストロークエンジンであってもよく、２ストロークエンジンであってもよい。エンジンは、キャニスタを有してもよく有さなくてもよい。エンジンは、過給装置（forced induction device）を有してもよく有さなくてもよい。過給装置はターボチャージャであってもよくスーパーチャージャであってもよい。エンジンの形式は、単一の燃焼室を有する単気筒エンジンであってもよく、複数の燃焼室を有する多気筒エンジンであってもよい。多気筒エンジンにおける複数の気筒（複数の燃焼室）の配列の形態は特に限定されない。多気筒エンジンの場合、複数の燃焼室に供給される燃料量の増加／減少の反転の周期は互いに同じまたはほぼ同じである。複数の燃焼室に燃料が供給されるタイミングは互いに異なってもよい。燃料室の数が４つ以上の場合、複数の燃焼室のうちの２つの燃焼室に燃料が供給されるタイミングが同じであってもよい。また、エンジンの用途は特に限定されない。例えば、エンジンは、車両、船舶等を構成するものであってもよい。また、エンジンが車両を構成するものである場合、車両とは、例えば、自動車、鞍乗型車両などである。鞍乗型車両とは、ライダー（運転者）が鞍にまたがるような状態で乗車する車両全般を指す。鞍乗型車両は、車輪を有してもよく有さなくてもよい。鞍乗型車両とは、自動二輪車、自動三輪車（motor tricycle）、四輪バギー（ＡＴＶ：All Terrain Vehicle / 全地形型車両）、スノーモービル、水上オートバイ（パーソナルウォータークラフト）などである。 In the present invention and embodiments, the engine fuel may be either gasoline fuel, alcohol fuel, mixed fuel of gasoline and alcohol, or light oil. The type of engine may be a 4-stroke engine or a 2-stroke engine. The engine may or may not have a canister. The engine may or may not have a forced induction device. The supercharger may be a turbocharger or a supercharger. The type of engine may be a single-cylinder engine with a single combustion chamber or a multi-cylinder engine with multiple combustion chambers. The form of arrangement of the plurality of cylinders (plurality of combustion chambers) in the multi-cylinder engine is not particularly limited. In the case of a multi-cylinder engine, the cycle of reversal of increase/decrease in the amount of fuel supplied to a plurality of combustion chambers is the same or substantially the same. Timings at which fuel is supplied to the plurality of combustion chambers may differ from each other. When the number of fuel chambers is four or more, the timing at which fuel is supplied to two of the plurality of combustion chambers may be the same. Also, the use of the engine is not particularly limited. For example, the engine may constitute a vehicle, a ship, or the like. Further, when the engine constitutes a vehicle, the vehicle includes, for example, an automobile and a straddle-type vehicle. A straddle-type vehicle refers to a vehicle in general in which a rider (driver) rides while straddling a saddle. A straddle-type vehicle may or may not have wheels. Straddle-type vehicles include motorcycles, motor tricycles, four-wheeled buggies (ATVs: All Terrain Vehicles), snowmobiles, personal water crafts, and the like.
　本発明および実施の形態において、触媒は、エンジンの燃焼室から排出された排ガスを浄化する。本発明および実施の形態において、触媒とは、三元触媒（ＴＷＣ：three way catalyst）、酸化触媒（ＤＯＣ）、ＮＯｘ選択還元用ＳＣＲ触媒、ＮＯｘ吸蔵還元触媒（ＬＮＴ）等である。三元触媒は、主に、大気汚染物質である、排ガス中の炭化水素（ＨＣ）、一酸化炭素（ＣＯ）、窒素酸化物（ＮＯｘ）の３物質を、酸化または還元することで除去する触媒のことをいう。三元触媒は、例えば、白金（Ｐｔ）、パラジウム（Ｐｄ）、ロジウム（Ｒｈ）を含む触媒である。三元触媒は、炭化水素が水と二酸化炭素に、一酸化炭素が二酸化炭素に、窒素酸化物が窒素に、それぞれ酸化または還元することで、排ガスを浄化する。ＮＯｘ選択還元用ＳＣＲ触媒は、金属置換ゼオライト、バナジウム、チタニア、酸化タングステン、銀、及びアルミナからなる群より選択される少なくとも１種を含有する。ＮＯｘ吸蔵還元触媒は、アルカリ金属、及び／又はアルカリ土類金属等である。アルカリ金属は、Ｋ、Ｎａ、Ｌｉ等である。アルカリ土類金属は、Ｃａ等である。なお、触媒は、炭化水素、一酸化炭素、および窒素酸化物のいずれか１つまたは２つを除去する触媒であってもよい。触媒は、酸化還元触媒でなくてもよい。触媒は、酸化または還元のいずれか一方だけで大気汚染物質を除去する酸化触媒または還元触媒であってもよい。触媒は、排ガス浄化作用を有する貴金属が基材に付着された構成となっている。触媒は、メタル基材の触媒であってもよいし、セラミック基材の触媒であってもよい。 In the present invention and embodiments, the catalyst purifies the exhaust gas discharged from the combustion chamber of the engine. In the present invention and embodiments, the catalyst is a three-way catalyst (TWC), an oxidation catalyst (DOC), an SCR catalyst for NOx selective reduction, a NOx storage reduction catalyst (LNT), or the like. A three-way catalyst is a catalyst that removes three substances, mainly hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx) in exhaust gas, which are atmospheric pollutants, by oxidizing or reducing them. That's what I mean. A three-way catalyst is, for example, a catalyst containing platinum (Pt), palladium (Pd) and rhodium (Rh). The three-way catalyst oxidizes or reduces hydrocarbons to water and carbon dioxide, carbon monoxide to carbon dioxide, and nitrogen oxides to nitrogen, respectively, thereby purifying the exhaust gas. The NOx selective reduction SCR catalyst contains at least one selected from the group consisting of metal-substituted zeolite, vanadium, titania, tungsten oxide, silver, and alumina. The NOx storage reduction catalyst is alkali metal and/or alkaline earth metal and the like. Alkali metals are K, Na, Li and the like. Alkaline earth metals are Ca and the like. The catalyst may be a catalyst that removes any one or two of hydrocarbons, carbon monoxide and nitrogen oxides. The catalyst need not be a redox catalyst. The catalyst may be an oxidation catalyst or a reduction catalyst that removes air pollutants by either oxidation or reduction alone. The catalyst has a structure in which a noble metal having an exhaust gas purifying action is adhered to a base material. The catalyst may be a metal-based catalyst or a ceramic-based catalyst.
　本発明および実施の形態において、上流酸素濃度センサおよび下流酸素濃度センサは、エンジンの燃焼室から排出された排ガス中の酸素濃度を検出する。以下、上流酸素濃度センサおよび下流酸素濃度センサを総称して、酸素濃度センサと称する場合がある。酸素濃度センサは、Ｏ２センサおよびリニアＡ／Ｆセンサを含む。Ｏ２センサは、排ガス中の酸素濃度が第１の濃度より高いことと、第２の濃度より低いことを検出する。第１の濃度は、第２の濃度より高くてもよく、同じでもよい。リニアＡ／Ｆセンサは、排ガス中の酸素濃度の変化を連続的に検出する。上流酸素濃度センサの信号に基づいて、混合気の空燃比がリッチとリーンのどちらであるかを検出することができる。混合気の空燃比がリッチであるとは、目標空燃比に対して燃料が過剰な状態をいう。混合気の空燃比がリーンであるとは、目標空燃比に対して空気が過剰な状態をいう。上流酸素濃度センサがリニアＡ／Ｆセンサの場合、目標空燃比は理論空燃比である。上流酸素濃度センサがＯ２センサの場合、目標空燃比は、理論空燃比を含む値または範囲であってもよく、理論空燃比から若干ずれた値または範囲であってもよい。混合気の空燃比がリッチのときに、上流酸素濃度センサの出力信号はリッチ状態となり、混合気の空燃比がリーンのときに、上流酸素濃度センサの出力信号はリーン状態となる。上流酸素濃度センサの出力信号のリッチ状態とは、例えば、出力信号の電圧値または電流値が第１の値よりも大きい状態である。この場合、上流酸素濃度センサの出力信号のリーン状態とは、出力信号の電圧値または電流値が第１の値と同じかそれよりも小さい第２の値よりも小さい状態である。酸素濃度センサは、例えばジルコニアを主体とした固体電解質体からなるセンサ素子部を有する。酸素濃度センサのセンサ素子部が、高温に加熱されて活性化状態となったときに、酸素濃度センサは酸素濃度を検知できる。 In the present invention and embodiments, the upstream oxygen concentration sensor and the downstream oxygen concentration sensor detect the oxygen concentration in the exhaust gas discharged from the combustion chamber of the engine. Hereinafter, the upstream oxygen concentration sensor and the downstream oxygen concentration sensor may be collectively referred to as oxygen concentration sensors. Oxygen concentration sensors include O2 sensors and linear A/F sensors. The O2 sensor detects that the oxygen concentration in the exhaust gas is higher than the first concentration and lower than the second concentration. The first concentration may be higher than or the same as the second concentration. A linear A/F sensor continuously detects changes in oxygen concentration in the exhaust gas. Whether the air-fuel ratio of the air-fuel mixture is rich or lean can be detected based on the signal of the upstream oxygen concentration sensor. When the air-fuel ratio of the air-fuel mixture is rich, it means that the amount of fuel is excessive with respect to the target air-fuel ratio. When the air-fuel ratio of the air-fuel mixture is lean, it means that the air is excessive with respect to the target air-fuel ratio. If the upstream oxygen concentration sensor is a linear A/F sensor, the target air-fuel ratio is the stoichiometric air-fuel ratio. When the upstream oxygen concentration sensor is an O2 sensor, the target air-fuel ratio may be a value or range including the stoichiometric air-fuel ratio, or may be a value or range slightly deviating from the stoichiometric air-fuel ratio. When the air-fuel ratio of the air-fuel mixture is rich, the output signal of the upstream oxygen concentration sensor is rich, and when the air-fuel ratio of the air-fuel mixture is lean, the output signal of the upstream oxygen concentration sensor is lean. The rich state of the output signal of the upstream oxygen concentration sensor is, for example, a state in which the voltage value or current value of the output signal is greater than the first value. In this case, the lean state of the output signal of the upstream oxygen concentration sensor is a state in which the voltage value or current value of the output signal is smaller than a second value equal to or smaller than the first value. The oxygen concentration sensor has a sensor element portion composed of a solid electrolyte body mainly composed of zirconia, for example. When the sensor element portion of the oxygen concentration sensor is heated to a high temperature and activated, the oxygen concentration sensor can detect the oxygen concentration.
　本発明および実施の形態において、上流酸素濃度センサの出力信号のリッチ／リーン状態の反転とは、上流酸素濃度センサの出力信号が、混合気の空燃比がリッチであることを示すリッチ状態から、混合気の空燃比がリーンであることを示すリーン状態に切り換わること、および、上流酸素濃度センサの出力信号が、リーン状態からリッチ状態に切り換わることである。混合気の空燃比がリッチからリーンに切り換わるときに上流酸素濃度センサ７６の出力信号がリッチ状態からリーン状態に切り換わる。混合気の空燃比がリーンからリッチに切り換わるときに上流酸素濃度センサ７６の出力信号がリーン状態からリッチ状態に切り換わる。 In the present invention and the embodiments, the reversal of the rich/lean state of the output signal of the upstream oxygen concentration sensor means that the output signal of the upstream oxygen concentration sensor changes from a rich state indicating that the air-fuel ratio of the air-fuel mixture is rich to One is switching to a lean state indicating that the air-fuel ratio of the air-fuel mixture is lean, and the other is that the output signal of the upstream oxygen concentration sensor switches from the lean state to the rich state. When the air-fuel ratio of the air-fuel mixture switches from rich to lean, the output signal of the upstream oxygen concentration sensor 76 switches from rich to lean. When the air-fuel ratio of the air-fuel mixture switches from lean to rich, the output signal of the upstream oxygen concentration sensor 76 switches from lean to rich.
　本発明および実施の形態において、第１信号反転タイミングとは、上流酸素濃度センサの出力信号がーン状態に切り換わるタイミング、または、上流酸素濃度センサの出力信号がリッチ状態に切り換わるタイミングのことである。
　本発明および実施の形態において、第２信号反転タイミングとは、第１信号反転タイミングにおいて上流酸素濃度センサの出力信号がリーン状態に切り換わる場合に、上流酸素濃度センサの出力信号が、リッチ状態に切り換わるタイミングのことである。また、本発明および実施の形態において、第２信号反転タイミングとは、第１信号反転タイミングにおいて上流酸素濃度センサの出力信号がリッチ状態に切り換わる場合に、上流酸素濃度センサの出力信号がリーン状態に切り換わるタイミングのことである。 In the present invention and the embodiment, the first signal inversion timing is the timing at which the output signal of the upstream oxygen concentration sensor switches to the low state or the timing at which the output signal of the upstream oxygen concentration sensor switches to the rich state. is.
In the present invention and the embodiments, the second signal inversion timing means that the output signal of the upstream oxygen concentration sensor changes to the rich state when the output signal of the upstream oxygen concentration sensor switches to the lean state at the first signal inversion timing. It is the timing of switching. In addition, in the present invention and the embodiments, the second signal inversion timing means that when the output signal of the upstream oxygen concentration sensor switches to the rich state at the first signal inversion timing, the output signal of the upstream oxygen concentration sensor is in the lean state. It is the timing of switching to
　本発明および実施の形態において、「前記第１信号反転タイミングの次に前記上流酸素濃度センサの出力信号のリッチ／リーン状態が反転する第２信号反転タイミング」とは、突発的信号反転組が発生していない状態で、第１信号反転タイミングの次に上流酸素濃度センサの出力信号のリッチ／リーン状態が反転するタイミングのことである。 In the present invention and the embodiments, "the second signal inversion timing at which the rich/lean state of the output signal of the upstream oxygen concentration sensor is inverted after the first signal inversion timing" means that a sudden signal inversion group occurs. It is the timing at which the rich/lean state of the output signal of the upstream oxygen concentration sensor is inverted next to the first signal inversion timing in the state where the oxygen concentration sensor is not in the state.
　本発明および実施の形態において、燃料量の増加／減少の反転とは、燃焼室に供給する燃料量が増加する状態から減少する状態に切り換わること、および、燃焼室に供給する燃料量が減少する状態から増加する状態に切り換わることである。 In the present invention and the embodiment, the reversal of the increase/decrease of the fuel amount means that the amount of fuel supplied to the combustion chamber is switched from increasing to decreasing, and the amount of fuel supplied to the combustion chamber is decreased. It is to switch from a state of increasing to a state of increasing.
　本発明および実施の形態において「前記上流酸素濃度センサの出力信号のリッチ／リーン状態の反転に基づいて、前記エンジンに供給する燃料量の増加／減少の反転が行われる」とは、例えば、上流酸素濃度センサの出力信号のリッチ／リーン状態が反転した後の状態が第１反転判定期間または第２反転判定期間継続したときに燃料量の増加／反転が行われることである。あるいは、「前記上流酸素濃度センサの出力信号のリッチ／リーン状態の反転に基づいて、前記エンジンに供給する燃料量の増加／減少の反転が行われる」とは、例えば、上流酸素濃度センサの出力信号のリッチ／リーン状態が反転した後の状態が第１反転判定期間または第２反転判定期間継続した場合に、その後さらに所定期間が経過したときに燃料量の増加／反転が行われることであってもよい。
　本発明および実施の形態において、第２反転判定期間の長さは、第１反転判定期間の長さと同じでもよく異なってもよい。 In the present invention and the embodiments, "reversing the increase/decrease of the fuel amount supplied to the engine is performed based on the reversal of the rich/lean state of the output signal of the upstream oxygen concentration sensor" means, for example, The fuel amount is increased/reversed when the state after the rich/lean state of the output signal of the oxygen concentration sensor is reversed continues for the first reversal determination period or the second reversal determination period. Alternatively, "reversing the increase/decrease of the fuel amount supplied to the engine is performed based on the reversal of the rich/lean state of the output signal of the upstream oxygen concentration sensor" means, for example, the output of the upstream oxygen concentration sensor If the state after the rich/lean state of the signal is reversed continues for the first reversal determination period or the second reversal determination period, the increase/reversal of the fuel amount is performed after a predetermined period of time has elapsed. may
In the present invention and embodiments, the length of the second inversion determination period may be the same as or different from the length of the first inversion determination period.
　本発明および実施の形態において「前記上流酸素濃度センサの出力信号の前記第２信号反転タイミングでのリッチ／リーン状態の反転に基づいて前記燃料量の増加／減少を反転させることが決定される」とは、例えば、第２信号反転タイミングに上流酸素濃度センサの出力信号のリッチ／リーン状態が反転した後の状態が継続することによって、燃料量の増加／減少の反転が決定されることである。燃料の増加／減少の反転は、燃料の増加／減少の反転が決定されたときに行われてもよいし、燃料の増加／減少の反転が決定された後、所定時間が経過したときに行われてもよい。 In the present invention and the embodiment, "it is determined to reverse the increase/decrease of the fuel amount based on the reversal of the rich/lean state of the output signal of the upstream oxygen concentration sensor at the second signal reversal timing." For example, when the rich/lean state of the output signal of the upstream oxygen concentration sensor continues after being reversed at the second signal inversion timing, the reversal of the increase/decrease of the fuel amount is determined. . The fuel increase/decrease reversal may be performed when the fuel increase/decrease reversal is determined, or may be performed when a predetermined time has elapsed after the fuel increase/decrease reversal has been determined. may be broken.
　本発明および実施の形態において、触媒劣化診断装置とは、プロセッサおよび記憶装置を有し、少なくとも本発明および本明細書に記載する触媒の劣化診断および燃料量の制御を実行する装置である。触媒劣化診断装置は、例えばＥＣＵ（Electronic Control Unit）でもよい。プロセッサは、請求項に記載された制御を実行できるように構成される。プロセッサには、マイクロコントローラ、ＣＰＵ（Central Processing Unit）、マイクロプロセッサ、マルチプロセッサ、特定用途向け集積回路（ＡＳＩＣ）、プログラム可能な論理回路（ＰＬＣ）、フィールドプログラマブルゲートアレイ（ＦＰＧＡ）および本明細書に記載する触媒の劣化状態の診断および燃料量の制御を実行することができる任意の他の回路が含まれる。記憶装置は、データやプログラムの保存または記憶を行うための装置である。記憶装置は、レジスタやキャッシュメモリ等の半導体メモリ、メインメモリ（主記憶装置／RAM）、ストレージ（外部記憶装置／補助記憶装置）等が含まれる。 In the present invention and the embodiments, the catalyst deterioration diagnosis device is a device that has a processor and a storage device and executes at least the catalyst deterioration diagnosis and fuel amount control described in the present invention and this specification. The catalyst deterioration diagnosis device may be, for example, an ECU (Electronic Control Unit). The processor is configured to perform the control recited in the claims. Processors include microcontrollers, CPUs (Central Processing Units), microprocessors, multiprocessors, application specific integrated circuits (ASICs), programmable logic circuits (PLCs), field programmable gate arrays (FPGAs) and herein Any other circuitry capable of diagnosing the state of catalyst deterioration and controlling fuel quantity described is included. A storage device is a device for saving or storing data and programs. Storage devices include semiconductor memories such as registers and cache memories, main memory (main memory device/RAM), storage (external memory device/auxiliary memory device), and the like.
　本発明および実施の形態において、触媒劣化診断装置は、下流酸素濃度センサの信号に基づいて触媒の劣化状態を診断する。例えば、触媒劣化診断装置は、下流酸素濃度センサの出力信号から得られた触媒の劣化に関連する触媒劣化判定値と、予め設定された触媒劣化判定閾値とに基づいて、触媒の劣化状態を診断する。例えば、触媒劣化診断装置は、触媒劣化判定値と触媒劣化判定閾値とを比較することによって、触媒の劣化状態を診断する。 In the present invention and embodiments, the catalyst deterioration diagnosis device diagnoses the deterioration state of the catalyst based on the signal from the downstream oxygen concentration sensor. For example, the catalyst deterioration diagnosis device diagnoses the deterioration state of the catalyst based on a catalyst deterioration judgment value related to deterioration of the catalyst obtained from the output signal of the downstream oxygen concentration sensor and a preset catalyst deterioration judgment threshold value. do. For example, the catalyst deterioration diagnosis device diagnoses the deterioration state of the catalyst by comparing the catalyst deterioration judgment value and the catalyst deterioration judgment threshold value.
　本発明および実施の形態において「触媒の劣化診断に適した触媒劣化診断間隔」は、触媒の劣化診断に用いられる下流酸素濃度センサの出力信号が検出されるときの信号反転間隔を含む。本発明および実施の形態において「前記信号反転間隔が前記触媒の劣化診断に適した触媒劣化診断間隔となるように前記エンジンが運転されている」とは、触媒の劣化診断のために燃料量が制御されることによって信号反転間隔が触媒の劣化診断に適した触媒劣化診断間隔となること、および、触媒劣化診断のためではなく燃料量が制御された結果、信号反転間隔が触媒の劣化診断に適した触媒劣化診断間隔となることを含む。触媒劣化診断のためではなく燃料量が制御された結果、信号反転間隔が触媒劣化診断間隔となる場合、触媒劣化診断間隔は、触媒の劣化診断に用いられる下流酸素濃度センサの出力信号が検出されるときの信号反転間隔であって、触媒の劣化診断が行われないときのいずれかの信号反転間隔と同じである。信号反転間隔が触媒劣化診断間隔となるようにエンジンが運転されているとき、複数の信号反転間隔は完全に同じでなくてもよい。つまり、触媒劣化診断間隔は数値範囲でよい。 In the present invention and the embodiment, the "catalyst deterioration diagnosis interval suitable for catalyst deterioration diagnosis" includes the signal inversion interval when the output signal of the downstream oxygen concentration sensor used for catalyst deterioration diagnosis is detected. In the present invention and the embodiment, "the engine is operated such that the signal inversion interval is a catalyst deterioration diagnosis interval suitable for the catalyst deterioration diagnosis" means that the fuel amount is increased for the catalyst deterioration diagnosis. By controlling, the signal inversion interval becomes a catalyst deterioration diagnosis interval suitable for diagnosing catalyst deterioration, and as a result of controlling the fuel amount instead of diagnosing catalyst deterioration, the signal inversion interval becomes suitable for diagnosing catalyst deterioration. This includes providing suitable catalyst deterioration diagnostic intervals. If the signal inversion interval becomes the catalyst deterioration diagnosis interval as a result of controlling the fuel amount and not for the catalyst deterioration diagnosis, the catalyst deterioration diagnosis interval is set so that the output signal of the downstream oxygen concentration sensor used for the catalyst deterioration diagnosis is detected. This signal inversion interval is the same as any signal inversion interval when the deterioration diagnosis of the catalyst is not performed. When the engine is operated such that the signal inversion interval is the catalyst deterioration diagnosis interval, the plurality of signal inversion intervals may not be exactly the same. That is, the catalyst deterioration diagnosis interval may be within a numerical range.
　本発明および実施の形態において、突発的信号反転組の長さとは、第１信号反転タイミングにおいて上流酸素濃度センサの出力信号がリーン状態に切り換わる場合に、突発的信号反転組の先のリッチ／リーン状態の反転において上流酸素濃度センサの出力信号がリッチ状態に切り換わったタイミングから、後のリッチ／リーン状態の反転において上流酸素濃度センサの出力信号がリーン状態に切り換わったタイミングまでの間隔のことである。本発明および実施の形態において、突発的信号反転組の長さとは、第１信号反転タイミングにおいて上流酸素濃度センサの出力信号がリッチ状態に切り換わる場合に、突発的信号反転組の先のリッチ／リーン状態の反転において上流酸素濃度センサの出力信号がリーン状態に切り換わったタイミングから、後のリッチ／リーン状態の反転において上流酸素濃度センサの出力信号がリッチ状態に切り換わったタイミングまでの間隔のことである。 In the present invention and the embodiments, the length of the sudden signal inversion set means that when the output signal of the upstream oxygen concentration sensor switches to the lean state at the first signal inversion timing, the length of the sudden signal inversion set before the rich/lean state. The interval from the timing when the output signal of the upstream oxygen concentration sensor switches to the rich state in the reversal of the lean state to the timing when the output signal of the upstream oxygen concentration sensor switches to the lean state in the subsequent reversal of the rich/lean state That is. In the present invention and the embodiments, the length of the sudden signal inversion set means that when the output signal of the upstream oxygen concentration sensor switches to the rich state at the first signal inversion timing, the length of the sudden signal inversion set before the rich/rich state is reached. The interval from the timing when the output signal of the upstream oxygen concentration sensor switches to the lean state in the reversal of the lean state to the timing when the output signal of the upstream oxygen concentration sensor switches to the rich state in the later reversal of the rich/lean state That is.
　本発明および実施の形態において「前記信号無効期間に前記突発的信号反転組が発生」するとは、信号無効期間内に、突発的信号反転組の先のリッチ／リーン状態の反転と後のリッチ／リーン状態の反転の両方が発生すること、および、信号無効期間内に突発的信号反転組の先のリッチ／リーン状態の反転が発生し、信号無効期間後に突発的信号反転組の後のリッチ／リーン状態の反転が発生することを含む。つまり、「前記信号無効期間に前記突発的信号反転組が発生」するとは、信号無効期間内に、突発的信号反転組を構成する２つの反転のうち少なくとも先の反転が発生することを意味する。信号無効期間内に突発的信号反転組の先のリッチ／リーン状態の反転が発生し、信号無効期間後に突発的信号反転組の後のリッチ／リーン状態の反転が発生する場合、信号無効期間の終了時から突発的信号反転組の後のリッチ／リーン状態までの期間の長さによっては、触媒劣化診断装置が突発的信号反転組を無視しない場合があってもよい。例えば、信号無効期間の終了時から突発的信号反転組の後のリッチ／リーン状態までの期間の長さが第１信号反転期間以上の場合、触媒劣化診断装置は突発的信号反転組を無視せずに燃料量を制御してもよい。言い替えると、信号無効期間の終了時から突発的信号反転組の後のリッチ／リーン状態までの期間の長さが第１信号反転期間よりも短い場合、触媒劣化診断装置は突発的信号反転組を無視する。 In the present invention and the embodiments, "the abrupt signal inversion group occurs during the signal invalid period" means that the rich/lean state before the abrupt signal inversion group is inverted and the rich/lean state after the abrupt signal inversion group occurs within the signal invalid period. The fact that both lean state inversions occur and that the rich/lean state inversions occur before the abrupt set of signal inversions within the signal null period and the rich/lean state inversions occur after the abrupt set of signal inversions after the signal null period. Including that a lean state reversal occurs. In other words, "the abrupt signal inversion group occurs during the signal invalid period" means that at least the first inversion of the two inversions forming the abrupt signal inversion group occurs within the signal invalid period. . If a rich/lean state inversion prior to the abrupt signal inversion set occurs within the signal ineffective period, and a rich/lean state inversion occurs after the abrupt signal inversion set after the signal ineffective period, the signal ineffective period Depending on the length of the period from the end to the rich/lean state after the sudden pair of signal inversions, the catalyst deterioration diagnosis device may not ignore the sudden pair of signal inversions. For example, if the length of the period from the end of the signal invalid period to the rich/lean state after the sudden signal inversion group is longer than or equal to the first signal inversion period, the catalyst deterioration diagnosis device cannot ignore the sudden signal inversion group. The fuel amount may be controlled without In other words, if the length of the period from the end of the signal invalid period to the rich/lean state after the sudden signal inversion group is shorter than the first signal inversion period, the catalyst deterioration diagnostic device selects the sudden signal inversion group. ignore.
　本発明および実施の形態において「前記信号無効期間を、前記エンジンの運転状態に応じて異なった長さに設定する」とは、例えば、エンジンの回転速度および／またはエンジンの負荷に応じて触媒劣化診断間隔が変更される場合に、触媒劣化診断間隔に応じて信号無効期間の長さを変更することである。 In the present invention and the embodiments, "setting the signal invalid period to a different length according to the operating state of the engine" means, for example, that the catalyst deteriorates according to the rotational speed of the engine and/or the load of the engine. To change the length of a signal invalid period according to a catalyst deterioration diagnosis interval when the diagnosis interval is changed.
　なお、例えば触媒劣化診断装置と上流酸素濃度センサとの間に設けたシミュレータを利用して、請求項に記載された本発明の触媒劣化診断装置による制御が行われているか否かを確認することができる。上流酸素濃度センサの出力信号の代わりに、シミュレータが発生させた疑似信号と上流酸素濃度センサの出力信号とを合わせた合成信号が、触媒劣化診断装置に入力される。上流酸素濃度センサの出力信号における信号反転間隔が触媒劣化診断間隔となるようにエンジンが運転されているときに、疑似信号が入力される。もし、上流酸素濃度センサの出力信号に突発的信号反転組が生じた場合、疑似信号の入力をやり直す。
　まず、シミュレータを利用して例えば以下の手順により第１反転判定期間を取得する。例えば図１０（ａ）、（ｄ）または図１０（ｂ）、（ｅ）に示すような、上流酸素濃度センサの出力信号のリッチ／リーン状態が反転したタイミング後ΔＴが経過したときに、合成信号のリッチ／リーン状態が反転するように疑似信号を入力する。疑似信号はごく短い時間だけ入力され、合成信号のリッチ／リーン状態はすぐに元に戻る。エンジンの運転状態などの条件を変えずに、このような疑似信号が、ΔＴがある程度長い期間から徐々に短くなるように繰り返しに入力する。但し、ΔＴの始点での上流酸素濃度センサの出力信号の反転は、全てリッチ状態への切り換わりか、全てリーン状態への切り換わりである。ΔＴの始点は、第２信号反転タイミングである。なお、図１０（ａ）、（ｂ）は、ΔＴの始点での上流酸素濃度センサの出力信号の反転が、全てリッチ状態への切り換わりである場合を示し、図１０（ｄ）、（ｅ）は、ΔＴの始点での上流酸素濃度センサの出力信号の反転が、全てリーン状態への切り換わりである場合を示す。そして、第２信号反転タイミングの後の最初の燃料量の増加／減少の反転のタイミングが、図１０（ｃ）、（ｆ）に示す、疑似信号が無い場合の第２信号反転タイミングの後の最初の燃料量の増加／減少の反転のタイミングと同じであるかどうか確認する。つまり、第２信号反転タイミングにおける上流酸素濃度センサの出力信号のリッチ／リーン状態の反転に基づく燃料量の増加／減少の反転が生じているか否かを確認する。図１０（ａ）、（ｄ）のように、ΔＴが所定の時間以上の間は、図１０（ｃ）、（ｆ）に示すのと同じタイミング燃料量の増加／減少の反転が生じる。図１０（ｂ）、（ｅ）のようにΔＴが所定の時間よりも短い場合は、図１０（ｃ）、（ｆ）に示すのと同じタイミングでは燃料量の増加／減少の反転が生じない。これにより、第２信号反転タイミングの後、前記所定の時間が経過したタイミングで、触媒劣化診断装置が第２信号反転タイミングでのリッチ／リーン状態の反転に基づいて燃料量の増加／減少を反転させることを決定しているということがわかる。前記所定の時間を第１反転判定期間として取得することができる。第２信号反転タイミングの後の最初の燃料量の増加／減少の反転のタイミングが、第２信号反転タイミングの後、第１反転判定期間が経過したタイミング、および、第２信号反転タイミングの後、第１反転判定期間よりも長い時間が経過したタイミングのいずれであっても、上述した手順で第１反転判定期間を取得することができる。なお、第２反転判定期間についても上述した手順と同様の手順で取得することができる。
　次に、合成信号に、例えば図１１（ａ）、（ｄ）に示すような、第１反転判定期間よりも長く、第１信号反転タイミングと第２信号反転タイミングとの間の期間内に収まるような信号反転組が生じるように疑似信号を入力する。つまり、疑似信号によって突発的信号反転組のダミーを生成する。例えば、第１信号反転タイミングから第２反転判定期間以上経過したときに信号反転組における先の反転が生じるように疑似信号が入力される。疑似信号による信号反転組に基づいて燃料量の増加／減少が反転するか否かかによって、請求項に記載された本発明の触媒劣化診断装置による制御が行われているか否かを確認することができる。図１１（ｂ）、（ｅ）は燃料量の増加／減少が反転しない場合を示し、図１１（ｃ）、（ｆ）は燃料量の増加／減少が反転する場合を示す。信号反転組における先のリッチ／リーン状態の反転のタイミング、後のリッチ／リーン状態の反転のタイミング、および、信号反転組の長さのうち少なくとも１つを変更した複数の信号反転組を順に触媒劣化診断装置に入力する。これら複数の信号反転組のうちいずれかの信号反転組に基づいて燃料量の増加／減少が反転しない場合に、請求項に記載された本発明の触媒劣化診断装置による制御が行われていると判断できる。
　信号反転組に基づいて燃料量の増加／減少が反転したか否かは、第１信号反転タイミングにおける上流酸素濃度センサの出力信号のリッチ／リーン状態の反転に基づく燃料量の増加／減少の反転のタイミングから、第２信号反転タイミングにおける上流酸素濃度センサの出力信号のリッチ／リーン状態の反転に基づく燃料量の増加／減少の反転のタイミングとの間の期間に、燃料量の増加／減少が反転したか否かによって確認することができる。
　いつ信号反転間隔が触媒劣化診断間隔となっていたか（いつ触媒の劣化診断を行ったか）の情報は、例えば外部スキャンツールを用いて取得することができる。外部スキャンツールは、触媒の劣化診断の結果、この診断に用いられた情報、および、この診断が行われたときの運転条件等を触媒劣化診断装置から読み取る装置である。外部スキャンツールは、触媒劣化診断装置に着脱可能に接続される。外部スキャンツールは、触媒劣化診断装置と無線で通信可能であってもよい。外部スキャンツールが取得する診断が行われたときの運転条件とは、例えば、エンジン回転速度、吸入空気量、スロットル弁の開度、吸気圧、燃料量の補正係数等である。燃料量の補正係数とは、基本燃料供給量に対する補正係数である。外部スキャンツールによって燃料量の補正係数の時間的変化を取得することで、エンジンに供給される燃料量の増加／減少の反転のタイミングを取得できる。
　燃料量の増加／減少が反転するタイミングは、エンジンに燃料を供給する燃料供給装置に触媒劣化診断装置から送られる信号に基づいて取得されてもよい。 It should be noted that, for example, a simulator provided between the catalyst deterioration diagnosis device and the upstream oxygen concentration sensor can be used to confirm whether or not the control by the catalyst deterioration diagnosis device of the present invention described in the claims is being performed. can be done. Instead of the output signal of the upstream oxygen concentration sensor, a synthesized signal obtained by combining the pseudo signal generated by the simulator and the output signal of the upstream oxygen concentration sensor is input to the catalyst deterioration diagnosis device. A pseudo signal is input when the engine is operated such that the signal inversion interval in the output signal of the upstream oxygen concentration sensor is equal to the catalyst deterioration diagnosis interval. If a sudden signal inversion group occurs in the output signal of the upstream oxygen concentration sensor, the pseudo signal is input again.
First, the simulator is used to acquire the first reversal determination period, for example, according to the following procedure. For example, as shown in FIGS. 10(a), (d) or FIGS. 10(b), (e), when ΔT has passed after the timing at which the rich/lean state of the output signal of the upstream oxygen concentration sensor is reversed, synthesis A dummy signal is input so that the rich/lean state of the signal is inverted. The spurious signal is input for only a short time and the rich/lean state of the synthesized signal quickly reverts. Without changing conditions such as the operating state of the engine, such a pseudo signal is repeatedly input such that ΔT is gradually shortened from a relatively long period. However, the reversal of the output signals of the upstream oxygen concentration sensors at the beginning of ΔT is either all switching to the rich state or all switching to the lean state. The starting point of ΔT is the second signal inversion timing. FIGS. 10(a) and 10(b) show that the inversion of the output signal of the upstream oxygen concentration sensor at the starting point of ΔT is all switching to the rich state, and FIGS. 10(d) and 10(e). ) shows the case where the reversal of the output signal of the upstream oxygen concentration sensor at the beginning of ΔT is all a switch to the lean state. Then, the timing of the first reversal of the fuel amount increase/decrease after the second signal reversal timing is after the second signal reversal timing when there is no pseudo signal, as shown in FIGS. Check if the timing is the same as the initial fuel amount increase/decrease reversal timing. That is, it is confirmed whether or not the reversal of increase/decrease of the fuel amount has occurred based on the reversal of the rich/lean state of the output signal of the upstream oxygen concentration sensor at the second signal reversal timing. As shown in FIGS. 10(a) and 10(d), while .DELTA.T is equal to or longer than the predetermined time, the timing fuel amount increases/decreases in the same reversal as shown in FIGS. 10(c) and 10(f). When ΔT is shorter than the predetermined time as shown in FIGS. 10(b) and (e), the increase/decrease of the fuel amount does not reverse at the same timing as shown in FIGS. 10(c) and (f). . As a result, after the second signal reversal timing, the catalyst deterioration diagnostic device reverses the increase/decrease of the fuel amount based on the reversal of the rich/lean state at the second signal reversal timing at the timing when the predetermined time has elapsed. I understand that you have decided to let The predetermined time can be acquired as the first reversal determination period. The timing of the first reversal of the fuel amount increase/decrease after the second signal reversal timing is the timing when the first reversal determination period has passed after the second signal reversal timing, and after the second signal reversal timing, The first reversal determination period can be acquired by the above-described procedure at any timing when a time longer than the first reversal determination period has elapsed. It should be noted that the second inversion determination period can also be acquired in the same procedure as described above.
Next, for example, as shown in FIGS. 11(a) and 11(d), the combined signal is longer than the first inversion determination period and falls within the period between the first signal inversion timing and the second signal inversion timing. A pseudo signal is input so as to generate such a signal inversion pair. That is, the pseudo signal generates a dummy of the sudden signal inversion set. For example, the dummy signal is input so that the previous inversion in the signal inversion group occurs when the second inversion determination period or more has elapsed from the first signal inversion timing. To confirm whether or not control is being performed by the catalyst deterioration diagnosis device of the present invention according to whether or not the increase/decrease of the fuel amount is reversed based on the signal inversion set by the pseudo signal. can be done. 11(b) and (e) show the case where the fuel amount increase/decrease is not reversed, and FIGS. 11(c) and (f) show the case where the fuel amount increase/decrease is reversed. catalyzing a plurality of signal inversion sets in which at least one of the timing of the prior rich/lean state inversion in the signal inversion set, the timing of the subsequent rich/lean state inversion, and the length of the signal inversion set is changed in sequence; Input to the deterioration diagnosis device. If the increase/decrease of the fuel amount is not reversed based on any one of the plurality of signal reversal sets, it is assumed that control by the catalyst deterioration diagnosis device of the present invention described in the claims is being performed. I can judge.
Whether the increase/decrease of the fuel amount has been reversed based on the signal inversion set is determined by the reversal of the increase/decrease of the fuel amount based on the reversal of the rich/lean state of the output signal of the upstream oxygen concentration sensor at the first signal reversal timing. and the timing of reversal of the fuel amount increase/decrease based on the reversal of the rich/lean state of the output signal of the upstream oxygen concentration sensor at the second signal reversal timing. It can be confirmed by whether or not it has been reversed.
Information about when the signal inversion interval was the catalyst deterioration diagnosis interval (when the catalyst deterioration diagnosis was performed) can be obtained using, for example, an external scan tool. The external scan tool is a device that reads the results of the catalyst deterioration diagnosis, the information used for this diagnosis, the operating conditions when this diagnosis was made, etc., from the catalyst deterioration diagnosis device. The external scan tool is detachably connected to the catalyst deterioration diagnosis device. The external scan tool may be able to wirelessly communicate with the catalyst deterioration diagnostic device. The operating conditions at the time of diagnosis acquired by the external scan tool include, for example, engine speed, intake air amount, throttle valve opening, intake pressure, fuel amount correction coefficient, and the like. The fuel amount correction factor is a correction factor for the basic fuel supply amount. By acquiring temporal changes in the correction coefficient of the fuel amount with an external scan tool, it is possible to acquire the timing of reversal of increase/decrease in the amount of fuel supplied to the engine.
The timing at which the increase/decrease of the fuel amount is reversed may be acquired based on a signal sent from the catalyst deterioration diagnosis device to the fuel supply device that supplies fuel to the engine.
　本発明および実施の形態において、複数の選択肢のうちの少なくとも１つ（一方）とは、複数の選択肢から考えられる全ての組み合わせを含む。複数の選択肢のうちの少なくとも１つ（一方）とは、複数の選択肢のいずれか１つであってもよく、複数の選択肢の全てであってもよい。例えば、ＡとＢとＣの少なくとも１つとは、Ａのみであってもよく、Ｂのみであってもよく、Ｃのみであってもよく、ＡとＢであってもよく、ＡとＣであってもよく、ＢとＣであってもよく、ＡとＢとＣであってもよい。
　本発明および実施の形態において、Ａおよび／またはＢとは、Ａでもよく、Ｂでもよく、ＡおよびＢの両方でもよいことを意味する。 In the present invention and embodiments, at least one (one) of a plurality of options includes all conceivable combinations of the plurality of options. At least one (one) of the multiple options may be any one of the multiple options, or may be all of the multiple options. For example, at least one of A, B and C may be A only, B only, C only, A and B, A and C There may be, it may be B and C, or it may be A, B and C.
In the present invention and embodiments, A and/or B means that it can be A, it can be B, it can be both A and B.
　特許請求の範囲において、ある構成要素の数を明確に特定しておらず、英語に翻訳された場合にこの構成要素が単数で表示される場合、本発明はこの構成要素を複数有してもよい。また、本発明はこの構成要素を１つだけ有してもよい。 If a claim does not explicitly specify the number of an element and that element appears in the singular when translated into English, the invention may include a plurality of that element. good. Also, the invention may have only one of this component.
　なお、本発明および実施の形態において、含む（including）、有する（having）、備える（comprising）およびこれらの派生語は、列挙されたアイテム及びその等価物に加えて追加的アイテムをも包含することが意図されて用いられている。 It should be noted that, as used in the present invention and embodiments, the terms including, having, comprising and derivatives thereof are intended to encompass additional items in addition to the recited items and their equivalents. is intended and used.
　他に定義されない限り、本明細書および請求範囲で使用される全ての用語（技術用語および科学用語を含む）は、本発明が属する当業者によって一般的に理解されるのと同じ意味を有する。一般的に使用される辞書に定義された用語のような用語は、関連する技術および本開示の文脈における意味と一致する意味を有すると解釈されるべきであり、理想化されたまたは過度に形式的な意味で解釈されることはない。 Unless defined otherwise, all terms (including technical and scientific terms) used in the specification and claims have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries are to be construed to have a meaning consistent with their meaning in the context of the relevant technology and this disclosure, and are not idealized or overly formal. not be interpreted in any meaningful way.
　本明細書において、「してもよい（でもよい）」という用語は非排他的なものである。「してもよい（でもよい）」は、「してもよい（でもよい）がこれに限定されるものではない」という意味である。本明細書において、「してもよい（でもよい）」は、「しない（ではない）」場合があることを暗黙的に含む。本明細書において、「してもよい（でもよい）」と記載された構成は、少なくとも、請求項１の構成により得られる上記効果を奏する。 In this specification, the term "may (can be)" is non-exclusive. "May be (may be)" means "may be (may be) but is not limited to". In this specification, "may (may)" implicitly includes "may not (may not)". In this specification, the configuration described as "may be (may be)" has at least the above effect obtained by the configuration of claim 1.
　本発明の実施形態を詳細に説明する前に、本発明は、以下の説明に記載されたまたは図面に図示された構成要素の構成および配置の詳細に制限されないことが理解されるべきである。本発明は、後述する実施形態以外の実施形態でも可能である。本発明は、後述する実施形態に様々な変更を加えた実施形態でも可能である。 Before describing embodiments of the present invention in detail, it should be understood that the present invention is not limited to the details of construction and arrangement of components set forth in the following description or illustrated in the drawings. The present invention is also possible in embodiments other than those described below. The present invention is also possible in embodiments in which various modifications are made to the embodiments described later.
　本発明の触媒劣化診断装置によると、触媒劣化診断が可能となる機会を多く確保することができる。 According to the catalyst deterioration diagnosis device of the present invention, it is possible to ensure many opportunities for catalyst deterioration diagnosis.
図１は本発明の第１実施形態の触媒劣化診断装置を説明するための図である。FIG. 1 is a diagram for explaining a catalyst deterioration diagnosis device according to a first embodiment of the present invention. 図２（ａ）～（ｃ）は第１実施形態に対する比較例１を説明するための図である。図２（ａ）は比較例１における上流酸素濃度センサの出力信号の変化を説明するための図であり、図２（ｂ）は信号無効期間を設定していない状態で突発的信号反転組Ｋ１ａまたは突発的信号反転組Ｋ２ａが発生した場合の燃料量の変化を説明するための図であり、図２（ｃ）は信号無効期間を設定していない状態で突発的信号反転組Ｋ１ｂまたは突発的信号反転組Ｋ２ｂが発生した場合の燃料量の変化を説明するための図である。2A to 2C are diagrams for explaining Comparative Example 1 with respect to the first embodiment. FIG. 2(a) is a diagram for explaining changes in the output signal of the upstream oxygen concentration sensor in Comparative Example 1, and FIG. 2(c) is a diagram for explaining changes in the amount of fuel when a sudden signal reversal group K2a occurs, and FIG. 2(c) shows a sudden signal reversal group K1b or a sudden FIG. 10 is a diagram for explaining changes in the amount of fuel when a signal inversion group K2b is generated; 図３（ａ）、（ｂ）は第１実施形態に対する比較例２を説明するための図である。図３（ａ）は比較例２における上流酸素濃度センサの出力信号の変化を説明するための図であり、図３（ｂ）は、長さの長い反転判定期間内に突発的信号反転組が発生したときの燃料量の変化を説明するための図である。FIGS. 3A and 3B are diagrams for explaining Comparative Example 2 with respect to the first embodiment. FIG. 3(a) is a diagram for explaining changes in the output signal of the upstream oxygen concentration sensor in Comparative Example 2, and FIG. It is a figure for demonstrating the change of the fuel amount when it generate|occur|produces. 図４は本発明の第２実施形態の触媒劣化診断装置が搭載された鞍乗型車両を説明するための図である。FIG. 4 is a diagram for explaining a straddle-type vehicle equipped with a catalyst deterioration diagnosis device according to a second embodiment of the present invention. 図５は本発明の第３実施形態の触媒劣化診断装置によって制御されるエンジンユニットの構成を示す模式図である。FIG. 5 is a schematic diagram showing the configuration of an engine unit controlled by a catalyst deterioration diagnosis device according to a third embodiment of the invention. 図６（ａ）は本発明の第４実施形態の触媒劣化診断装置において触媒の劣化診断を行うときの処理の流れを示すフローチャートであり、図６（ｂ）は、図６（ａ）のフローに沿って処理が行われるときの触媒の劣化診断時の燃料量の変化を示す図である。FIG. 6(a) is a flow chart showing the flow of processing when diagnosing deterioration of the catalyst in the catalyst deterioration diagnosis device of the fourth embodiment of the present invention, and FIG. 6(b) is the flow of FIG. 6(a). FIG. 10 is a diagram showing changes in the amount of fuel during deterioration diagnosis of the catalyst when processing is performed along . 図７は、上流酸素濃度センサのリッチ／リーン状態の変化と燃料量の増加／減少との関係、ならびに、燃料量の増加および減少の詳細を説明するための図である。FIG. 7 is a diagram for explaining the relationship between the rich/lean state change of the upstream oxygen concentration sensor and the fuel amount increase/decrease, and the details of the fuel amount increase and decrease. 図８は本発明の第５実施形態の触媒劣化診断装置における触媒の劣化診断を含む処理の流れを説明するためのフローチャートである。FIG. 8 is a flow chart for explaining the flow of processing including catalyst deterioration diagnosis in the catalyst deterioration diagnosis device according to the fifth embodiment of the present invention. 図９（ａ）は本発明の第６実施形態の触媒劣化診断装置により、触媒劣化診断間隔が長くなるようにエンジンが運転されるときの信号無効期間を説明するための図であり、図９（ｂ）は本発明の第６実施形態の触媒劣化診断装置により触媒劣化診断間隔が短くなるようにエンジンが運転されるときの信号無効期間を説明するための図である。FIG. 9(a) is a diagram for explaining the signal invalid period when the engine is operated so that the catalyst deterioration diagnosis interval is lengthened by the catalyst deterioration diagnosis device according to the sixth embodiment of the present invention. (b) is a diagram for explaining a signal invalid period when the engine is operated so that the catalyst deterioration diagnosis interval is shortened by the catalyst deterioration diagnosis device according to the sixth embodiment of the present invention. 図１０（ａ）～図１０（ｆ）は本発明の触媒劣化診断装置による制御が行われているか否かを確認する手順の一部を説明するための図である。図１０（ａ）は、ΔＴの始点での上流酸素濃度センサの出力信号の反転が全てリッチ状態への切り換わりであり、合成信号におけるΔＴが第１反転判定期間よりも長い場合の、燃料量の変化を説明するための図であり、図１０（ｂ）は、ΔＴの始点での上流酸素濃度センサの出力信号の反転が全てリッチ状態への切り換わりであり、合成信号におけるΔＴが第１反転判定期間以下の場合の、燃料量の変化を説明するための図であり、図１０（ｃ）は、上流酸素濃度センサの出力信号の反転がリッチ状態への切り換わり、かつ、合成信号が疑似信号を含まない場合の燃料量の変化を説明するための図であり、図１０（ｄ）は、ΔＴの始点での上流酸素濃度センサの出力信号の反転が全てリーン状態への切り換わりであり、合成信号におけるΔＴが第１反転判定期間よりも長い場合の、燃料量の変化を説明するための図であり、図１０（ｅ）は、ΔＴの始点での上流酸素濃度センサの出力信号の反転が全てリーン状態への切り換わりであり、合成信号におけるΔＴが第１反転判定期間以下の場合の、燃料量の変化を説明するための図であり、図１０（ｆ）は、上流酸素濃度センサの出力信号の反転がリーン状態への切り換わり、かつ、合成信号が疑似信号を含まない場合の燃料量の変化を説明するための図である。FIGS. 10(a) to 10(f) are diagrams for explaining part of the procedure for confirming whether or not the control by the catalyst deterioration diagnosis device of the present invention is being performed. FIG. 10(a) shows that the reversal of the output signal of the upstream oxygen concentration sensor at the starting point of ΔT is all switching to the rich state, and the fuel amount when ΔT in the combined signal is longer than the first reversal determination period. FIG. 10(b) shows that the inversion of the output signal of the upstream oxygen concentration sensor at the starting point of ΔT is all switching to the rich state, and ΔT in the combined signal is the first FIG. 10(c) is a diagram for explaining changes in the amount of fuel when the inversion determination period or less is reached, and FIG. FIG. 10(d) is a diagram for explaining changes in the fuel amount when no pseudo signal is included. 10(e) is an output signal of the upstream oxygen concentration sensor at the starting point of ΔT, and FIG. is a switch to a lean state, and ΔT in the combined signal is less than or equal to the first reversal determination period. FIG. FIG. 10 is a diagram for explaining changes in the amount of fuel when the inversion of the output signal of the concentration sensor is switched to the lean state and the combined signal does not contain the pseudo signal; 図１１（ａ）～図１１（ｆ）は本発明の触媒劣化診断装置による制御が行われているか否かを確認する手順の一部を説明するための図である。図１１（ａ）は上流酸素濃度センサの出力信号がリッチ状態に切り換わった後リーン状態に切り換わるまでの期間に、疑似信号によって生成した突発的信号反転組のダミーを説明するための図であり、図１１（ｂ）は信号無効期間が設けられている状態で図１１（ａ）の信号が触媒劣化診断装置に入力された場合の燃料量の変化を説明するための図であり、図１１（ｃ）は信号無効期間が設けられていない状態で図１１（ａ）の信号が触媒劣化診断装置に入力された場合の燃料量の変化を説明するための図であり、図１１（ｄ）は上流酸素濃度センサの出力信号がリーン状態に切り換わった後リッチ状態に切り換わるまでの期間に、疑似信号によって生成した突発的信号反転組のダミーを説明するための図であり、図１１（ｅ）は信号無効期間が設けられている状態で図１１（ｄ）の信号が触媒劣化診断装置に入力された場合の燃料量の変化を説明するための図であり、図１１（ｆ）は信号無効期間が設けられていない状態で図１１（ｄ）の信号が触媒劣化診断装置に入力された場合の燃料量の変化を説明するための図である。FIGS. 11(a) to 11(f) are diagrams for explaining part of the procedure for confirming whether or not the control by the catalyst deterioration diagnosis device of the present invention is being performed. FIG. 11(a) is a diagram for explaining the dummies of the abrupt signal inversion group generated by the pseudo signal during the period from when the output signal of the upstream oxygen concentration sensor switches to the rich state to when it switches to the lean state. FIG. 11(b) is a diagram for explaining changes in the fuel amount when the signal of FIG. 11(c) is a diagram for explaining changes in the fuel amount when the signal of FIG. 11(a) is input to the catalyst deterioration diagnosis device in a state where no signal invalid period is provided; ) is a diagram for explaining the dummies of the sudden signal reversal group generated by the pseudo signal during the period from when the output signal of the upstream oxygen concentration sensor switches to the lean state to the rich state; FIG. FIG. 11(e) is a diagram for explaining changes in the fuel amount when the signal of FIG. 11(d) is input to the catalyst deterioration diagnosis device in a state in which the signal invalid period is provided; 11B is a diagram for explaining changes in the amount of fuel when the signal of FIG. 11D is input to the catalyst deterioration diagnosis device in a state in which no signal invalid period is provided; FIG.
　＜第１実施形態＞
　本発明の第１実施形態の触媒劣化診断装置８０について、図１を用いて説明する。
図１に示すように、第１実施形態の触媒劣化診断装置８０は、エンジンユニット１１に対して設けられている。エンジンユニット１１は、エンジン２０と、触媒５３と、上流酸素濃度センサ７６と、下流酸素濃度センサ７７とを有する。
　エンジン２０は４ストロークのエンジンであってもよいし、２ストロークのエンジンであってもよい。上流酸素濃度センサ７６は、エンジン２０の燃焼室３０から排出された排ガスの流れ方向において触媒５３の上流に配置される。上流酸素濃度センサ７６の出力信号は、混合気の空燃比がリッチであるかリーンであるかに応じた信号である。混合気の空燃比がリッチであることを示す上流酸素濃度センサ７６の出力信号のリッチ状態は、例えば、出力信号の値Ｖｊが第１の値Ｖｊ１よりも大きい状態である。混合気の空燃比がリーンであることを示す上流酸素濃度センサ７６の出力信号のリーン状態は、例えば、出力信号の値Ｖｊが第２の値Ｖｊ２よりも小さい状態である。第２の値Ｖｊ２は、第１の値Ｖｊ１と同じかそれより小さい。下流酸素濃度センサ７７は、排ガスの流れ方向における触媒５３の下流に配置される。 <First Embodiment>
A catalyst deterioration diagnostic device 80 according to a first embodiment of the present invention will be described with reference to FIG.
As shown in FIG. 1, the catalyst deterioration diagnosis device 80 of the first embodiment is provided for the engine unit 11. As shown in FIG. The engine unit 11 has an engine 20 , a catalyst 53 , an upstream oxygen concentration sensor 76 and a downstream oxygen concentration sensor 77 .
Engine 20 may be a four-stroke engine or a two-stroke engine. The upstream oxygen concentration sensor 76 is arranged upstream of the catalyst 53 in the flow direction of the exhaust gas discharged from the combustion chamber 30 of the engine 20 . The output signal of the upstream oxygen concentration sensor 76 is a signal corresponding to whether the air-fuel ratio of the air-fuel mixture is rich or lean. A rich state of the output signal of the upstream oxygen concentration sensor 76 indicating that the air-fuel ratio of the air-fuel mixture is rich is, for example, a state in which the value Vj of the output signal is greater than the first value Vj1. A lean state of the output signal of the upstream oxygen concentration sensor 76 indicating that the air-fuel ratio of the air-fuel mixture is lean is, for example, a state in which the value Vj of the output signal is smaller than the second value Vj2. The second value Vj2 is equal to or less than the first value Vj1. The downstream oxygen concentration sensor 77 is arranged downstream of the catalyst 53 in the flow direction of the exhaust gas.
　触媒劣化診断装置８０は、燃料量Ｈを制御する。触媒劣化診断装置８０は、上流酸素濃度センサ７６の出力信号のリッチ／リーン状態の反転に基づいて、燃料量Ｈの増加／減少の反転が行われるようにエンジン２０を運転させる。
　触媒劣化診断装置８０は、上流酸素濃度センサ７６の出力信号がリーン状態に切り換わるタイミング（例えば図１の信号反転タイミングＴ１ａ、Ｔ３ａ、Ｔ５ａ）から反転判定期間Ｒ１経過したタイミング（例えば図１のタイミングＴ１ｂ、Ｔ３ｂ、Ｔ５ｂ）に、燃料量Ｈを減少させる状態から増加させる状態へ反転させること、すなわち、燃料量Ｈの増加／減少を反転させることを決定する。そして、触媒劣化診断装置８０は、この決定に基づいて、燃料量Ｈを増加させる。すなわち、燃料量Ｈの増加／減少を反転させる。
　また、触媒劣化診断装置８０は、上流酸素濃度センサ７６の出力信号がリッチ状態に切り換わるタイミング（例えば図１のタイミング信号反転タイミングＴ２ａ、Ｔ４ａ）から反転判定期間Ｒ２経過したタイミング（例えば図１のタイミングＴ２ｂ、Ｔ４ｂ）に、燃料量Ｈを増加させる状態から減少させる状態へ反転させること、すなわち、燃料量Ｈの増加／減少を反転させることを決定する。なお、反転判定期間Ｒ２は、反転判定期間Ｒ１と同じであってもよいし、反転判定期間Ｒ１と異なっていてもよい。そして、触媒劣化診断装置８０は、この決定に基づいて、燃料量Ｈを減少させる。すなわち、燃料量Ｈの増加／減少を反転させる。
　上流酸素濃度センサ７６の出力信号のリッチ／リーン状態が反転する第１信号反転タイミングと、第１信号反転タイミングの次に上流酸素濃度センサ７６の出力信号のリッチ／リーン状態が反転する第２信号反転タイミングとの間隔を信号反転間隔と定義する。例えば、第１信号反転タイミングが図１の信号反転タイミングＴ１ａの場合、第２信号反転タイミングは図１の信号反転タイミングＴ２ａである。第１信号反転タイミングが図１の信号反転タイミングＴ２ａの場合、第２信号反転タイミングは図１の信号反転タイミングＴ３ａである。第１信号反転タイミングは、図１の信号反転タイミングＴ３ａ、信号反転タイミングＴ４ａ、または、信号反転タイミングＴ５ａであってもよい。第１信号反転タイミングが信号反転タイミングＴ１ａ、Ｔ３ａ、Ｔ５ａの場合、反転判定期間Ｒ２が本発明の第１反転判定期間に相当する。第１信号反転タイミングが信号反転タイミングＴ２ａ、Ｔ４ａの場合、反転判定期間Ｒ１が本発明の第１反転判定期間に相当する。 The catalyst deterioration diagnosis device 80 controls the fuel amount H. The catalyst deterioration diagnosis device 80 operates the engine 20 so that the increase/decrease of the fuel amount H is reversed based on the rich/lean state reversal of the output signal of the upstream oxygen concentration sensor 76 .
The catalyst deterioration diagnosis device 80 detects the timing (for example, the signal inversion timings T1a, T3a, and T5a in FIG. 1) at which the output signal of the upstream oxygen concentration sensor 76 switches to the lean state and the timing (for example, the timing in FIG. 1) after the inversion determination period R1 has passed. At T1b, T3b, T5b), it is decided to reverse the state of decreasing the fuel quantity H to the state of increasing it, that is, to reverse the increase/decrease of the fuel quantity H. Then, the catalyst deterioration diagnosis device 80 increases the fuel amount H based on this determination. That is, the increase/decrease of the fuel amount H is reversed.
Further, the catalyst deterioration diagnosis device 80 detects the timing (for example, the timing signal inversion timings T2a and T4a in FIG. 1) at which the output signal of the upstream oxygen concentration sensor 76 switches to the rich state, and the timing (for example, timing signal inversion timings T2a and T4a in FIG. At timings T2b and T4b), it is decided to reverse the state of increasing the fuel amount H to the state of decreasing it, that is, to reverse the increase/decrease of the fuel amount H. Note that the inversion determination period R2 may be the same as the inversion determination period R1, or may be different from the inversion determination period R1. Then, the catalyst deterioration diagnosis device 80 reduces the fuel amount H based on this determination. That is, the increase/decrease of the fuel amount H is reversed.
A first signal inversion timing at which the rich/lean state of the output signal of the upstream oxygen concentration sensor 76 is inverted, and a second signal at which the rich/lean state of the output signal of the upstream oxygen concentration sensor 76 is inverted after the first signal inversion timing. An interval from the inversion timing is defined as a signal inversion interval. For example, when the first signal inversion timing is the signal inversion timing T1a in FIG. 1, the second signal inversion timing is the signal inversion timing T2a in FIG. When the first signal inversion timing is the signal inversion timing T2a in FIG. 1, the second signal inversion timing is the signal inversion timing T3a in FIG. The first signal inversion timing may be the signal inversion timing T3a, the signal inversion timing T4a, or the signal inversion timing T5a in FIG. When the first signal inversion timings are the signal inversion timings T1a, T3a, and T5a, the inversion determination period R2 corresponds to the first inversion determination period of the present invention. When the first signal inversion timings are the signal inversion timings T2a and T4a, the inversion determination period R1 corresponds to the first inversion determination period of the present invention.
　また、触媒劣化診断装置８０は、第１信号反転タイミングと第２信号反転タイミングとの間隔である信号反転間隔が、触媒５３の劣化診断に適した触媒劣化診断間隔Ｗ１、Ｗ２となるようにエンジン２０が運転されているときに、下流酸素濃度センサ７７の信号に基づいて、触媒５３の劣化診断を行う。ここで、触媒劣化診断間隔Ｗ１は、第１信号反転タイミングにリーン状態に切り換わる場合の触媒劣化診断間隔である。触媒劣化診断間隔Ｗ２は、第１信号反転タイミングにリッチ状態に切り換わる場合の触媒劣化診断間隔である。触媒劣化診断間隔Ｗ１と触媒劣化診断間隔Ｗ２とは同じであってもよいし、異なっていてもよい。
　また、触媒劣化診断装置８０は、信号反転間隔が触媒劣化診断間隔Ｗ１、Ｗ２となるようにエンジン２０が運転されているときの第１信号反転タイミングと第２信号反転タイミングとの間の期間に、信号無効期間Ｍ１、Ｍ２を設けて燃料量Ｈを制御する。信号無効期間Ｍ１は、第１信号反転タイミングにリーン状態に切り換わる場合の信号無効期間である。信号無効期間Ｍ２は、第１信号反転タイミングにリッチ状態に切り換わる場合の信号無効期間である。信号無効期間Ｍ１の長さと信号無効期間Ｍ２の長さとは同じであってもよいし、異なっていてもよい。信号無効期間Ｍ１、Ｍ２の開始タイミングと終了タイミングは図１に示すタイミングに限らない。
　信号反転間隔が触媒劣化診断間隔Ｗ１、Ｗ２となるようにエンジン２０が運転されているとき、第１信号反転タイミングと第２信号反転タイミングとの間の期間に、突発的信号反転組が突発的に発生する場合がある。突発的信号反転組は、上流酸素濃度センサ７６の出力信号におけるリッチ／リーン状態の反転とこれに続くリッチ／リーン状態の反転との組である。触媒劣化診断装置８０は、信号無効期間Ｍ１に突発的信号反転組が発生し、且つ、当該突発的信号反転組の長さが反転判定期間Ｒ２（第１反転判定期間）よりも長く、且つ、当該突発的信号反転組が第１信号反転タイミングと第２反転タイミングとの間に収まっている場合に、当該突発的信号反転組を無視して、燃料量Ｈの増加／減少の反転を行わせないように制御する。触媒劣化診断装置８０は、信号無効期間Ｍ２に突発的信号反転組が発生し、且つ、当該突発的信号反転組の長さが反転判定期間Ｒ１（第１反転判定期間）よりも長く、且つ、当該突発的信号反転組が第１信号反転タイミングと第２反転タイミングとの間に収まっている場合に、当該突発的信号反転組を無視して、燃料量Ｈの増加／減少の反転を行わせないように制御する。 Further, the catalyst deterioration diagnosis device 80 controls the engine so that the signal inversion interval, which is the interval between the first signal inversion timing and the second signal inversion timing, becomes the catalyst deterioration diagnosis intervals W1 and W2 suitable for diagnosing the deterioration of the catalyst 53 . 20 is operated, based on the signal of the downstream oxygen concentration sensor 77, the deterioration diagnosis of the catalyst 53 is performed. Here, the catalyst deterioration diagnosis interval W1 is the catalyst deterioration diagnosis interval when switching to the lean state at the first signal inversion timing. The catalyst deterioration diagnosis interval W2 is the catalyst deterioration diagnosis interval when the state is switched to the rich state at the first signal inversion timing. The catalyst deterioration diagnosis interval W1 and the catalyst deterioration diagnosis interval W2 may be the same or different.
In addition, the catalyst deterioration diagnosis device 80 detects the signal inversion intervals between the first signal inversion timing and the second signal inversion timing when the engine 20 is operated such that the signal inversion intervals are equal to the catalyst deterioration diagnosis intervals W1 and W2. , signal invalid periods M1 and M2 are provided to control the fuel amount H. The signal invalid period M1 is a signal invalid period when switching to the lean state at the first signal inversion timing. The signal invalid period M2 is a signal invalid period when switching to the rich state at the first signal inversion timing. The length of the signal invalid period M1 and the length of the signal invalid period M2 may be the same or different. The start timing and end timing of the signal invalid periods M1 and M2 are not limited to the timings shown in FIG.
When the engine 20 is operated such that the signal inversion intervals are equal to the catalyst deterioration diagnosis intervals W1 and W2, the sudden signal inversion group is suddenly generated in the period between the first signal inversion timing and the second signal inversion timing. may occur. A set of abrupt signal inversions is a set of rich/lean state inversions followed by rich/lean state inversions in the upstream oxygen concentration sensor 76 output signal. In the catalyst deterioration diagnosis device 80, a sudden signal inversion group occurs during the signal invalid period M1, and the length of the sudden signal inversion group is longer than the inversion determination period R2 (first inversion determination period), and When the sudden signal inversion set is between the first signal inversion timing and the second inversion timing, the sudden signal inversion set is ignored and the increase/decrease of the fuel amount H is reversed. control to prevent The catalyst deterioration diagnosis device 80 generates a sudden signal inversion group during the signal invalid period M2, and the length of the sudden signal inversion group is longer than the inversion determination period R1 (first inversion determination period), and When the sudden signal inversion set is between the first signal inversion timing and the second inversion timing, the sudden signal inversion set is ignored and the increase/decrease of the fuel amount H is reversed. control to prevent
　例えば、信号反転タイミングＴ１ａと信号反転タイミングＴ２ａとの間に設けた信号無効期間Ｍ１に、図１に破線で示すような突発的信号反転組Ｋ１ａまたは突発的信号反転組Ｋ１ｂが発生した場合、および、信号反転タイミングＴ２ａと信号反転タイミングＴ３ａとの間に設けた信号無効期間Ｍ２に、図１に破線で示すような突発的信号反転組Ｋ２ａまたは突発的信号反転組Ｋ２ｂが発生した場合について説明する。
　突発的信号反転組Ｋ１ａは、タイミングＵ１ａにおけるリッチ／リーン状態の反転と、タイミングＵ１ａの後のタイミングＵ１ｂにおけるリッチ／リーン状態の反転の組である。突発的信号反転組Ｋ１ｂは、タイミングＵ１ｃにおけるリッチ／リーン状態の反転と、タイミングＵ１ｃの後のタイミングＵ１ｄにおけるリッチ／リーン状態の反転の組である。突発的信号反転組Ｋ１ａの長さＸ１ａ、および、突発的信号反転組Ｋ１ｂの長さＸ１ｂは、反転判定期間Ｒ２よりも長い。突発的信号反転組Ｋ１ａ、Ｋ１ｂは信号反転タイミングＴ１ａと信号反転タイミングＴ２ａとの間に収まる。タイミングＵ１ａとタイミングＵ１ｂは共に信号無効期間Ｍ１内である。タイミングＵ１ｃは信号無効期間Ｍ１内であり、タイミングＵ１ｂは信号無効期間Ｍ１より後である。
　触媒劣化診断装置８０は、信号無効期間Ｍ１に突発的信号反転組Ｋ１ａまたは突発的信号反転組Ｋ１ｂが発生した場合、突発的信号反転組Ｋ１ａ、Ｋ１ｂを無視して燃料量Ｈを制御する。
　突発的信号反転組Ｋ２ａは、タイミングＵ２ａにおけるリッチ／リーン状態の反転と、タイミングＵ２ａの後のタイミングＵ２ｂにおけるリッチ／リーン状態の反転の組である。突発的信号反転組Ｋ２ｂは、タイミングＵ２ｃにおけるリッチ／リーン状態の反転と、タイミングＵ２ｃの後のタイミングＵ２ｄにおけるリッチ／リーン状態の反転の組である。突発的信号反転組Ｋ２ａの長さＸ２ａおよび突発的信号反転組Ｋ２ｂの長さＸ２ｂは、反転判定期間Ｒ１よりも長い。突発的信号反転組Ｋ２ａ、Ｋ２ｂは信号反転タイミングＴ２ａと信号反転タイミングＴ３ａとの間に収まる。タイミングＵ２ａとタイミングＵ２ｂは共に信号無効期間Ｍ２内である。タイミングＵ２ｃは信号無効期間Ｍ１内であり、タイミングＵ２ｂは信号無効期間Ｍ１より後である。
　触媒劣化診断装置８０は、信号無効期間Ｍ２に突発的信号反転組Ｋ２ａまたは突発的信号反転組Ｋ２ｂが発生した場合、突発的信号反転組Ｋ２ａ、Ｋ２ｂを無視して燃料量Ｈを制御する。このように、第１実施形態においては、後述する比較例１（図２（ａ）～（ｃ）参照）とは異なり、突発的信号反転組Ｋ１ａ、Ｋ１ｂ、Ｋ２ａ、Ｋ２ｂに基づいた燃料量Ｈの増加／減少の反転が行われない。 For example, in the signal invalid period M1 provided between the signal inversion timing T1a and the signal inversion timing T2a, when a sudden signal inversion group K1a or a sudden signal inversion group K1b as indicated by the dashed line in FIG. 1 occurs, and A case where a sudden signal inversion group K2a or a sudden signal inversion group K2b as indicated by the dashed line in FIG. .
The abrupt signal inversion set K1a is a set of rich/lean state inversions at timing U1a and rich/lean state inversions at timing U1b after timing U1a. The abrupt signal inversion set K1b is a set of rich/lean state inversions at timing U1c and rich/lean state inversions at timing U1d after timing U1c. The length X1a of the sudden signal inversion group K1a and the length X1b of the sudden signal inversion group K1b are longer than the inversion determination period R2. The abrupt signal inversion set K1a and K1b falls between the signal inversion timing T1a and the signal inversion timing T2a. Both the timing U1a and the timing U1b are within the signal invalid period M1. The timing U1c is within the signal invalid period M1, and the timing U1b is after the signal invalid period M1.
When the sudden signal inversion group K1a or the sudden signal inversion group K1b occurs during the signal invalid period M1, the catalyst deterioration diagnosis device 80 ignores the sudden signal inversion group K1a and K1b and controls the fuel amount H.
The abrupt signal inversion set K2a is a set of rich/lean state inversions at timing U2a and rich/lean state inversions at timing U2b after timing U2a. The abrupt signal inversion set K2b is a set of rich/lean state inversions at timing U2c and rich/lean state inversions at timing U2d after timing U2c. The length X2a of the abrupt signal inversion group K2a and the length X2b of the abrupt signal inversion group K2b are longer than the inversion determination period R1. The abrupt signal inversion set K2a and K2b falls between the signal inversion timing T2a and the signal inversion timing T3a. Both the timing U2a and the timing U2b are within the signal invalid period M2. The timing U2c is within the signal invalid period M1, and the timing U2b is after the signal invalid period M1.
The catalyst deterioration diagnosis device 80 controls the fuel amount H by ignoring the sudden signal inversion group K2a and K2b when the sudden signal inversion group K2a or the sudden signal inversion group K2b occurs during the signal invalid period M2. As described above, in the first embodiment, unlike Comparative Example 1 (see FIGS. 2A to 2C), which will be described later, the fuel amount H no reversal of the increase/decrease of
　そして、第１実施形態において、信号無効期間Ｍ１、Ｍ２を設けることにより、信号無効期間Ｍ１、Ｍ２に突発的信号反転組Ｋ１ａ、Ｋ１ｂ、Ｋ２ａ、Ｋ２ｂが発生しても、突発的信号反転組Ｋ１ａ、Ｋ１ｂ、Ｋ２ａ、Ｋ２ｂが発生しない場合と比較して、燃料量Ｈの増加／減少の反転の間隔が短くなることを抑制できる。これにより、触媒５３の劣化診断が可能となる機会を多く確保することができる。 In the first embodiment, by providing the signal invalid periods M1 and M2, even if the sudden signal inversion groups K1a, K1b, K2a, and K2b occur during the signal invalid periods M1 and M2, the sudden signal inversion group K1a , K1b, K2a, and K2b do not occur, it is possible to suppress the interval between the increase/decrease reversal of the fuel amount H from becoming shorter. As a result, many opportunities for diagnosing deterioration of the catalyst 53 can be secured.
　ここで、第１実施形態と異なり、例えば後述する比較例２のように、信号無効期間Ｍ１、Ｍ２を設ける代わりに、反転判定期間Ｒ１、Ｒ２を長くすることによって、突発的信号反転組Ｋ１ａ、Ｋ１ｂ、Ｋ２ａ、Ｋ２ｂが発生したときに、突発的信号反転組Ｋ１ａ、Ｋ１ｂ、Ｋ２ａ、Ｋ２ｂに基づいて燃料量Ｈの増加／減少が反転されないようにすることが考えられる。しかしながら、反転判定期間Ｒ１、Ｒ２を長くしすぎると、上流酸素濃度センサ７６の出力信号に正常な反転（信号反転タイミングＴ１ａ、Ｔ２ａ、Ｔ３ａ、Ｔ４ａ、Ｔ５ａでの反転）が発生した場合にも、燃料量Ｈの増加／減少が反転されなくなってしまうことがある。
　これに対して、第１実施形態では、上述したように、信号無効期間Ｍ１、Ｍ２を設けることによって、突発的信号反転組Ｋ１ａ、Ｋ１ｂ、Ｋ２ａ、Ｋ２ｂに基づく燃料量Ｈの増加／減少を反転させないようにしている。これにより、長さの長い突発的信号に基づいて燃料量Ｈの増加／減少を反転しないようにしつつも、上流酸素濃度センサ７６の出力信号に正常な反転が発生したときには確実に燃料量Ｈの増加／減少を反転させることができる。その結果、燃料量Ｈの増加／減少の反転の間隔が触媒劣化診断間隔Ｗ１、Ｗ２よりも長くなることを抑制できる。これにより、触媒５３の劣化診断が可能となる機会を確保することができる。 Here, unlike the first embodiment, instead of providing the signal invalid periods M1 and M2 as in Comparative Example 2, which will be described later, the inversion determination periods R1 and R2 are lengthened so that the abrupt signal inversion group K1a, It is conceivable to prevent the increase/decrease of the fuel amount H from being reversed based on the abrupt signal inversion set K1a, K1b, K2a, and K2b when K1b, K2a, and K2b occur. However, if the reversal determination periods R1 and R2 are made too long, even if normal reversal occurs in the output signal of the upstream oxygen concentration sensor 76 (reversal at the signal reversal timings T1a, T2a, T3a, T4a, and T5a), The increase/decrease of the fuel amount H may not be reversed.
In contrast, in the first embodiment, as described above, the signal invalid periods M1 and M2 are provided to reverse the increase/decrease of the fuel amount H based on the abrupt signal inversion sets K1a, K1b, K2a, and K2b. I try not to let As a result, while preventing the increase/decrease of the fuel amount H from reversing based on a long abrupt signal, the fuel amount H can be reliably reverted when a normal reversal occurs in the output signal of the upstream oxygen concentration sensor 76. Increase/decrease can be reversed. As a result, it is possible to prevent the interval between the increase/decrease reversal of the fuel amount H from becoming longer than the catalyst deterioration diagnosis intervals W1 and W2. As a result, it is possible to secure an opportunity to diagnose deterioration of the catalyst 53 .
　また、後述する比較例２のように反転判定期間Ｒ１、Ｒ２を長くした場合、信号反転間隔が長くなる。
　これに対して、信号無効期間Ｍ１、Ｍ２の長さは信号反転間隔の長さにほとんど影響しない。したがって、信号無効期間Ｍ１、Ｍ２を設けるために触媒劣化診断間隔（信号反転間隔）を長くする必要がない。そのため、比較例２に比べて、触媒５３の劣化診断が可能となる機会をより多く確保することができる。また、第１実施形態では、比較例２に比べて、触媒劣化診断間隔（信号反転間隔）の長さの設定自由度が高い。 Further, when the inversion determination periods R1 and R2 are lengthened as in Comparative Example 2, which will be described later, the signal inversion interval is lengthened.
On the other hand, the lengths of the signal invalid periods M1 and M2 hardly affect the length of the signal inversion interval. Therefore, it is not necessary to lengthen the catalyst deterioration diagnosis interval (signal inversion interval) in order to provide the signal invalid periods M1 and M2. Therefore, compared with Comparative Example 2, more opportunities for diagnosing deterioration of the catalyst 53 can be secured. In addition, in the first embodiment, the degree of freedom in setting the length of the catalyst deterioration diagnosis interval (signal inversion interval) is higher than in the second comparative example.
　触媒劣化診断装置８０が燃料量Ｈを減少させる状態から増加させる状態へ反転させることを決定するタイミングと、触媒劣化診断装置８０が燃料量Ｈを減少させる状態から増加させる状態へ反転させるタイミングとの差を、追加時間Ｑ１とする。信号反転間隔が触媒劣化診断間隔Ｗ１、Ｗ２となるようにエンジン２０が運転されているときの追加時間Ｑ１は、図１に示すように０より大きくてもよく、０であってもよい。信号反転タイミングＴ１ａ、Ｔ３ａ、Ｔ５ａから反転判定期間Ｒ１と追加時間Ｑ１とを足し合わせた時間（Ｒ１＋Ｑ１）経過したタイミングＴ１ｃ、Ｔ３ｃ、Ｔ５ｃに、燃料量Ｈの増加／減少が反転する。
　触媒劣化診断装置８０が燃料量Ｈを増加させる状態から減少させる状態へ反転させることを決定するタイミングと、触媒劣化診断装置８０が燃料量Ｈを増加させる状態から減少させる状態へ反転させるタイミングとの差を、追加時間Ｑ２とする。信号反転間隔が触媒劣化診断間隔Ｗ１、Ｗ２となるようにエンジン２０が運転されているときの追加時間Ｑ２は、図１に示すように０より大きくてもよく、０であってもよい。信号反転タイミングＴ２ａ、Ｔ４ａから反転判定期間Ｒ２と追加時間Ｑ２とを足し合わせた時間（Ｒ２＋Ｑ２）経過したタイミングＴ２ｃ、Ｔ４ｃに、燃料量Ｈの増加／減少が反転する。 The timing at which the catalyst deterioration diagnosis device 80 decides to reverse the fuel quantity H from the state of decreasing to the state of increasing it, and the timing at which the catalyst deterioration diagnosis device 80 reverses the state from the state of decreasing the fuel quantity H to the state of increasing it. Let the difference be the additional time Q1. The additional time Q1 when the engine 20 is operated such that the signal inversion intervals are equal to the catalyst deterioration diagnosis intervals W1 and W2 may be greater than 0 as shown in FIG. 1, or may be 0. The increase/decrease of the fuel amount H is reversed at timings T1c, T3c, and T5c after the sum of the reversal determination period R1 and the additional time Q1 (R1+Q1) has elapsed from the signal reversal timings T1a, T3a, and T5a.
The timing at which the catalyst deterioration diagnosis device 80 decides to reverse the state of increasing the fuel quantity H to the state of decreasing it, and the timing at which the catalyst deterioration diagnosis device 80 reverses the state from increasing the fuel quantity H to the state of decreasing it. Let the difference be the additional time Q2. The additional time Q2 when the engine 20 is operated such that the signal inversion intervals are equal to the catalyst deterioration diagnosis intervals W1 and W2 may be greater than 0 as shown in FIG. 1, or may be 0. The increase/decrease of the fuel amount H is reversed at timings T2c and T4c after a time (R2+Q2) obtained by adding the reversal determination period R2 and the additional time Q2 from the signal reversal timings T2a and T4a.
　第１実施形態において、信号無効期間Ｍ１、Ｍ２の開始タイミングは、第１信号反転タイミングから第２反転判定期間が経過したタイミングであってもよい。
　例えば、第１信号反転タイミングが、図１の信号反転タイミングＴ１ａ、Ｔ３ａ、Ｔ５ａである場合、反転判定期間Ｒ１が第２反転判定期間である。そして、信号無効間隔Ｍ１の開始タイミングは、信号反転タイミングＴ１ａ、Ｔ３ａ、Ｔ５ａからそれぞれ反転判定期間Ｒ１が経過したタイミングＴ１ｂ、Ｔ３ｂ、Ｔ５ｂであってもよい。
　また、第１信号反転タイミングが図１の信号反転タイミングＴ２ａ、Ｔ４ａである場合、反転判定期間Ｒ２が本発明の第２反転判定期間である。そして、信号無効間隔Ｍ２の開始タイミングは、信号反転タイミングＴ２ａ、Ｔ４ａからそれぞれ反転判定期間Ｒ２が経過したタイミングＴ２ｂ、Ｔ４ｂであってもよい。
　あるいは、信号無効期間Ｍ１、Ｍ２の開始タイミングは、第１信号反転タイミングから第２反転判定期間が経過したタイミングと、第２信号反転タイミングとの間のタイミングでもよい。 In the first embodiment, the start timing of the signal invalid periods M1 and M2 may be the timing after the second inversion determination period has elapsed from the first signal inversion timing.
For example, when the first signal inversion timings are the signal inversion timings T1a, T3a, and T5a in FIG. 1, the inversion determination period R1 is the second inversion determination period. The start timing of the signal invalid interval M1 may be timings T1b, T3b, and T5b when the inversion determination period R1 has passed from the signal inversion timings T1a, T3a, and T5a.
Further, when the first signal inversion timings are the signal inversion timings T2a and T4a in FIG. 1, the inversion determination period R2 is the second inversion determination period of the present invention. The start timing of the signal invalid interval M2 may be timings T2b and T4b when the inversion determination period R2 has passed from the signal inversion timings T2a and T4a.
Alternatively, the start timing of the signal invalid periods M1 and M2 may be the timing between the second signal inversion timing and the timing when the second inversion determination period has elapsed from the first signal inversion timing.
　＜第１実施形態に対する比較例１＞
　次に、第１実施形態と比較される比較例１について、図２（ａ）～（ｃ）を用いて説明する。図２（ａ）に示すように、比較例１では、第１信号反転タイミングと第２信号反転タイミングとの間に信号無効期間Ｍ１、Ｍ２が設けられていない。これ以外の点は第１実施形態と同じである。
　信号無効期間Ｍ１が設けられた第１実施形態においては、上述したように、反転判定期間Ｒ２よりも長い長さＸ１ａ、Ｘ１ｂを有する突発的信号反転組Ｋ１ａ、Ｋ１ｂが発生しても、突発的信号反転組Ｋ１ａ、Ｋ１ｂが無視される。そのため、タイミングＵ１ａから時間（Ｒ２＋Ｑ２）が経過したタイミングに、燃料量Ｈの増加／減少が反転しない。また、タイミングＵ１ｃから時間（Ｒ２＋Ｑ２）が経過したタイミングに、燃料量Ｈの増加／減少が反転しない。
　これに対して、信号無効期間Ｍ１が設けられていない比較例１において、反転判定期間Ｒ２よりも長い長さＸ１ａを有する突発的信号反転組Ｋ１ａが発生すると、図２（ｂ）に破線で示すように、タイミングＵ１ａから時間（Ｒ２＋Ｑ２）が経過したタイミングに、燃料量Ｈの増加／減少が反転してしまう。
　また、信号無効期間Ｍ１が設けられていない比較例１において、反転判定期間Ｒ１よりも長い長さＸ１ｂを有する突発的信号反転組Ｋ１ｂが発生すると、図２（ｃ）に破線で示すように、タイミングＵ１ｃから時間（Ｒ２＋Ｑ２）が経過したタイミングに、燃料量Ｈの増加／減少が反転してしまう。
　また、信号無効期間Ｍ２が設けられた第１実施形態においては、上述したように、反転判定期間Ｒ１よりも長い長さＸ２ａ、Ｘ２ｂを有する突発的信号反転組Ｋ２ａ、Ｋ２ｂが発生しても、突発的信号反転組Ｋ２ａ、Ｋ２ｂが無視される。そのため、タイミングＵ２ａから時間（Ｒ１＋Ｑ１）が経過したタイミングに、燃料量Ｈの増加／減少が反転しない。また、タイミングＵ２ｃから時間（Ｒ１＋Ｑ１）が経過したタイミングに、燃料量Ｈの増加／減少が反転しない。
　これに対して、信号無効期間Ｍ２が設けられていない比較例１において、反転判定期間Ｒ１よりも長い長さＸ２ａを有する突発的信号反転組Ｋ２ａが発生すると、図２（ｂ）に破線で示すように、タイミングＵ２ａから時間（Ｒ１＋Ｑ１）が経過したタイミングに、燃料量Ｈの増加／減少が反転してしまう。
　また、信号無効期間Ｍ２が設けられていない比較例１において、反転判定期間Ｒ１よりも長い長さＸ２ｂを有する突発的信号反転組Ｋ２ｂが発生すると、図２（ｃ）に破線で示すように、タイミングＵ２ｃから時間（Ｒ１＋Ｑ１）が経過したタイミングに、燃料量Ｈの増加／減少が反転してしまう。 <Comparative example 1 for the first embodiment>
Next, Comparative Example 1 compared with the first embodiment will be described with reference to FIGS. 2(a) to 2(c). As shown in FIG. 2A, in Comparative Example 1, the signal invalid periods M1 and M2 are not provided between the first signal inversion timing and the second signal inversion timing. Other points are the same as the first embodiment.
In the first embodiment in which the signal invalid period M1 is provided, as described above, even if the abrupt signal inversion pairs K1a and K1b having the lengths X1a and X1b longer than the inversion determination period R2 are generated, the abrupt Signal inversion set K1a, K1b is ignored. Therefore, the increase/decrease of the fuel amount H is not reversed at the timing when the time (R2+Q2) has passed from the timing U1a. Further, the increase/decrease of the fuel amount H is not reversed at the timing when the time (R2+Q2) has passed from the timing U1c.
On the other hand, in Comparative Example 1 in which the signal invalid period M1 is not provided, if a sudden signal inversion set K1a having a length X1a longer than the inversion determination period R2 is generated, it is indicated by a broken line in FIG. 2(b). Thus, the increase/decrease of the fuel amount H is reversed at the timing when the time (R2+Q2) has passed from the timing U1a.
In addition, in Comparative Example 1 in which the signal invalid period M1 is not provided, when an abrupt signal inversion group K1b having a length X1b longer than the inversion determination period R1 is generated, as indicated by the dashed line in FIG. 2(c), At the timing when the time (R2+Q2) has passed from the timing U1c, the increase/decrease of the fuel amount H is reversed.
Further, in the first embodiment in which the signal invalid period M2 is provided, as described above, even if the abrupt signal inversion pairs K2a and K2b having lengths X2a and X2b longer than the inversion determination period R1 are generated, The abrupt signal inversion set K2a, K2b is ignored. Therefore, the increase/decrease of the fuel amount H is not reversed at the timing when the time (R1+Q1) has passed from the timing U2a. Further, the increase/decrease of the fuel amount H is not reversed at the timing when the time (R1+Q1) has passed from the timing U2c.
On the other hand, in Comparative Example 1 in which the signal invalid period M2 is not provided, if a sudden signal inversion set K2a having a length X2a longer than the inversion determination period R1 is generated, it is indicated by a broken line in FIG. 2(b). Thus, the increase/decrease of the fuel amount H is reversed at the timing after the time (R1+Q1) has passed from the timing U2a.
In addition, in Comparative Example 1 in which the signal invalid period M2 is not provided, when a sudden signal inversion set K2b having a length X2b longer than the inversion determination period R1 is generated, as indicated by the dashed line in FIG. 2(c), At the timing when the time (R1+Q1) has passed from the timing U2c, the increase/decrease of the fuel amount H is reversed.
　信号無効期間Ｍ１、Ｍ２を設けない比較例１では、突発的信号反転組Ｋ１ａ、Ｋ１ｂ、Ｋ２ａ、Ｋ２ｂが発生したときに、上述したように、突発的信号反転組Ｋ１ａ、Ｋ１ｂ、Ｋ２ａ、Ｋ２ｂに基づいて燃料量Ｈの増加／減少が反転されてしまう。そのため、信号無効期間Ｍ１、Ｍ２を設けない比較例１では、突発的信号反転組Ｋ１ａ、Ｋ１ｂ、Ｋ２ａ、Ｋ２ｂが発生していないときと比較して、燃料量Ｈの増加／減少の反転の間隔が短くなり、触媒５３の劣化診断を行うことができなくなる。すなわち、触媒５３の劣化診断が可能となる機会が少なくなる。 In Comparative Example 1 in which the signal invalid periods M1 and M2 are not provided, when the abrupt signal inversion groups K1a, K1b, K2a, and K2b occur, the abrupt signal inversion groups K1a, K1b, K2a, and K2b Based on this, the increase/decrease of the fuel amount H is reversed. Therefore, in Comparative Example 1 in which the signal invalid periods M1 and M2 are not provided, the interval between the increase/decrease inversions of the fuel amount H is longer than when the sudden signal inversion groups K1a, K1b, K2a, and K2b are not generated. becomes shorter, and deterioration diagnosis of the catalyst 53 cannot be performed. That is, the chances of diagnosing the deterioration of the catalyst 53 are reduced.
　＜第１実施形態に対する比較例２＞
　次に、第１実施形態と比較される比較例２について、図３（ａ）、（ｂ）を用いて説明する。図３（ａ）に示すように、比較例２では、第１信号反転タイミングと第２信号反転タイミングとの間に信号無効期間Ｍ１、Ｍ２が設けられていない。さらに比較例２では、第１実施形態の反転判定期間Ｒ１の代わりに反転判定期間Ｒ１よりも長い反転判定期間Ｒ１ａが設定され、第１実施形態の反転判定期間Ｒ２の代わりに反転判定期間Ｒ２よりも長い反転判定期間Ｒ２ａが設定される。これ以外の点は第１実施形態と同じである。反転判定期間Ｒ１ａ、Ｒ２ａが第１実施形態の反転判定期間Ｒ１、Ｒ２ｂよりも長いため、比較例２の信号反転間隔は、第１実施形態の信号反転間隔よりも長くなる。
　比較例２では、上流酸素濃度センサ７６の出力信号がリーン状態に切り換わるタイミング（例えば図３（ａ）の信号反転タイミングＴ１ａ１、Ｔ３ａ１）から反転判定期間Ｒ１ａ経過したタイミング（例えば図３（ａ）のタイミングＴ１ｂ１、Ｔ３ｂ１）に、燃料量Ｈを減少させる状態から増加させる状態へ反転させることが決定される。さらに、図３（ｂ）に示すように、上記タイミング（例えば図３（ａ）のタイミングＴ１ｂ１、Ｔ３ｂ１）から追加時間Ｑ１経過したタイミング（例えば図３（ａ）、（ｂ）のタイミングＴ１ｃ１、Ｔ３ｃ１）に燃料量Ｈの増加／減少が反転する。
　また、比較例２では、上流酸素濃度センサ７６の出力信号がリッチ状態に切り換わるタイミング（例えば図３（ａ）のタイミング信号反転タイミングＴ２ａ１、Ｔ４ａ１）から反転判定期間Ｒ２ａ経過したタイミング（例えば図３（ａ）のタイミングＴ２ｂ１、Ｔ４ｂ１）に、燃料量Ｈを増加させる状態から減少させる状態へ反転させることが決定される。そして、図３（ｂ）に示すように、上記タイミング（例えば図３（ａ）のタイミングＴ２ｂ１、Ｔ４ｂ１）から追加時間Ｑ２経過したタイミング（例えば図３（ａ）、（ｂ）のタイミングＴ２ｃ１、Ｔ４ｃ１）に燃料量Ｈの増加／減少が反転する。
　反転判定期間Ｒ１ａは、第１実施形態で説明した突発的信号反転組Ｋ１ａ、Ｋ１ｂの長さＸ１ａ、Ｘ１ｂ（図１参照）よりも長い。反転判定期間Ｒ２ａは、第１実施形態で説明した突発的信号反転組Ｋ２ａ、Ｋ２ｂの長さＸ２ａ、Ｘ２ｂ（図１参照）よりも長い。したがって、比較例２では、長さＸ１ａ、Ｘ１ｂより長く反転判定期間Ｒ１ａより短い長さの突発的信号反転組が発生した場合、この突発的信号反転組に基づいて燃料量Ｈの増加／減少が反転することがない。
　しかしながら、比較例２の場合、反転判定期間Ｒ１ａ、Ｒ２ａが長いため、信号反転タイミングＴ１ａ１、Ｔ３ａ１、から反転判定期間Ｒ１ａが経過するまでの期間、および、信号反転タイミングＴ２ａ１、Ｔ２ａ１から反転判定期間Ｒ２ａが経過するまでの期間に突発的信号反転組が発生する可能性が高くなる。そして、例えば、信号反転タイミングＴ１ａ１から第１実施形態の反転判定期間Ｒ１が経過したタイミングＴ１ｂ２と、タイミングＴ１ｂ１との間の期間に、図３（ａ）に破線で示すような、反転判定期間Ｒ１ａよりも長さの短い突発的信号反転組Ｊ１が発生した場合、タイミングＴ１ｂ１燃料量Ｈを増加させることが決定されない。したがって、図３（ｂ）に破線で示すように、タイミングＴ１ｃ１に燃料量Ｈの増加／減少が反転しない。すなわち、上流酸素濃度センサ７６の出力信号が信号反転タイミングＴ１ａ１にリーン状態に切り換わったことに基づいて燃料量Ｈの増加／減少が反転しない。その結果、燃料量Ｈの増加／減少の反転の間隔が触媒劣化診断間隔よりも長くなってしまう。また、例えば、信号反転タイミングＴ２ａ１から第１実施形態の反転判定期間Ｒ２が経過したタイミングＴ２ｂ２と、タイミングＴ２ｂ１との間の期間に、図３（ａ）に破線で示すような、反転判定期間Ｒ２ａよりも長さの短い突発的信号反転組Ｊ２が発生した場合、タイミングＴ２ｂ１に燃料量Ｈを増加させることが決定されない。したがって、図３（ｂ）に破線で示すように、タイミングＴ２ｃ１に燃料量Ｈの増加／減少が反転しない。すなわち、上流酸素濃度センサ７６の出力信号が信号反転タイミングＴ２ａ１にリッチ状態に切り換わったことに基づいて燃料量Ｈの増加／減少が反転しない。その結果、燃料量Ｈの増加／減少の反転の間隔が劣化診断間隔よりも長くなってしまう。
　比較例２では、上流酸素濃度センサ７６の出力信号に正常な反転が生じたときにも燃料量の増加／減少が反転されなくなる可能性が高くなる。この場合、燃料量Ｈの増加／減少の反転の間隔が触媒劣化診断間隔よりも長くなって、触媒５３の劣化診断を行うことができなくなる。すなわち、触媒５３の劣化診断が可能となる機会が少なくなる。
　また、反転判定期間Ｒ１ａ、Ｒ２ａを長くするほど信号反転間隔は長くなる。このことによっても、触媒５３の劣化診断が可能となる機会が少なくなる。また、比較例２では、触媒劣化診断間隔（信号反転間隔）の長さの設定自由度が低い。 <Comparative example 2 with respect to the first embodiment>
Next, Comparative Example 2 to be compared with the first embodiment will be described with reference to FIGS. As shown in FIG. 3A, in Comparative Example 2, the signal invalid periods M1 and M2 are not provided between the first signal inversion timing and the second signal inversion timing. Furthermore, in Comparative Example 2, a reversal determination period R1a longer than the reversal determination period R1 is set instead of the reversal determination period R1 of the first embodiment, and a reversal determination period R2 is set instead of the reversal determination period R2 of the first embodiment. A longer reversal determination period R2a is set. Other points are the same as the first embodiment. Since the inversion determination periods R1a and R2a are longer than the inversion determination periods R1 and R2b of the first embodiment, the signal inversion interval of Comparative Example 2 is longer than the signal inversion interval of the first embodiment.
In Comparative Example 2, the output signal of the upstream oxygen concentration sensor 76 is switched to the lean state (for example, signal reversal timings T1a1 and T3a1 in FIG. (timings T1b1, T3b1), it is decided to reverse the state of decreasing the fuel quantity H to the state of increasing it. Furthermore, as shown in FIG. 3(b), timings (for example, timings T1c1 and T3c1 in FIGS. 3(a) and 3(b)) after an additional time Q1 has elapsed from the above timings (for example, timings T1b1 and T3b1 in FIG. 3(a)) ), the increase/decrease of the fuel amount H is reversed.
In Comparative Example 2, the output signal of the upstream oxygen concentration sensor 76 switches to the rich state (for example, timing signal inversion timings T2a1 and T4a1 in FIG. At timings T2b1 and T4b1 in (a), it is decided to reverse the state of increasing the fuel amount H to the state of decreasing it. Then, as shown in FIG. 3(b), timings (for example, timings T2c1 and T4c1 in FIGS. 3(a) and 3(b)) after the additional time Q2 has elapsed from the above timings (for example, timings T2b1 and T4b1 in FIG. 3(a)) ), the increase/decrease of the fuel amount H is reversed.
The inversion determination period R1a is longer than the lengths X1a and X1b (see FIG. 1) of the abrupt signal inversion pairs K1a and K1b described in the first embodiment. The inversion determination period R2a is longer than the lengths X2a and X2b (see FIG. 1) of the abrupt signal inversion pairs K2a and K2b described in the first embodiment. Therefore, in Comparative Example 2, when a sudden signal inversion set having a length longer than the lengths X1a and X1b and shorter than the inversion determination period R1a occurs, the fuel amount H is increased/decreased based on this sudden signal inversion set. cannot be reversed.
However, in the case of Comparative Example 2, since the inversion determination periods R1a and R2a are long, the period from the signal inversion timings T1a1 and T3a1 until the inversion determination period R1a elapses and from the signal inversion timings T2a1 and T2a1 to the inversion determination period R2a. There is a high possibility that an abrupt signal inversion group will occur during the period until . Then, for example, during the period between the timing T1b2 when the reversal determination period R1 of the first embodiment has passed from the signal reversal timing T1a1, and the timing T1b1, an inversion determination period R1a as indicated by the dashed line in FIG. If a sudden signal reversal set J1 having a length shorter than that occurs, it is not decided to increase the fuel amount H at timing T1b1. Therefore, as indicated by the dashed line in FIG. 3(b), the increase/decrease of the fuel amount H does not reverse at timing T1c1. That is, the increase/decrease of the fuel amount H is not reversed based on the fact that the output signal of the upstream oxygen concentration sensor 76 is switched to the lean state at the signal reversal timing T1a1. As a result, the interval between the increase/decrease reversal of the fuel amount H becomes longer than the catalyst deterioration diagnosis interval. Further, for example, during the period between the timing T2b2 when the reversal determination period R2 of the first embodiment has passed from the signal reversal timing T2a1 and the timing T2b1, a reversal determination period R2a as indicated by the dashed line in FIG. If the sudden signal inversion group J2 having a length shorter than 1 is generated, it is not decided to increase the fuel amount H at the timing T2b1. Therefore, as indicated by the dashed line in FIG. 3(b), the increase/decrease of the fuel amount H is not reversed at timing T2c1. That is, the increase/decrease of the fuel amount H is not reversed based on the fact that the output signal of the upstream oxygen concentration sensor 76 is switched to the rich state at the signal reversal timing T2a1. As a result, the interval between the increase/decrease reversal of the fuel amount H becomes longer than the deterioration diagnosis interval.
In Comparative Example 2, even when the output signal of the upstream oxygen concentration sensor 76 normally reverses, there is a high possibility that the increase/decrease of the fuel amount will not be reversed. In this case, the interval between the increase/decrease reversal of the fuel amount H becomes longer than the catalyst deterioration diagnosis interval, and deterioration diagnosis of the catalyst 53 cannot be performed. That is, the chances of diagnosing the deterioration of the catalyst 53 are reduced.
Further, the longer the inversion determination periods R1a and R2a, the longer the signal inversion interval. This also reduces the chances of diagnosing deterioration of the catalyst 53 . Further, in Comparative Example 2, the degree of freedom in setting the length of the catalyst deterioration diagnosis interval (signal inversion interval) is low.
　＜第２実施形態＞
　本発明の第２実施形態の触媒劣化診断装置８０が搭載される鞍乗型車両１について図４に基づいて説明する。第２実施形態は、第１実施形態の構成を有する。
　図４に示すように、鞍乗型車両１は、エンジンユニット１１と触媒劣化診断装置８０とを備えている。エンジンユニット１１は、エンジン２０と、排気通路部５１と、触媒５３と、上流酸素濃度センサ７６と、下流酸素濃度センサ７７とを備える。エンジン２０の冷却方式は、図４では自然空冷式であるが、その他の冷却方式でもよい。エンジン２０は、図４では４ストローク式のエンジンであるが、２ストローク式のエンジンであってもよい。排気通路部５１における触媒５３の位置は、図４に示す位置に限らない。 <Second embodiment>
A straddle-type vehicle 1 equipped with a catalyst deterioration diagnostic device 80 according to a second embodiment of the present invention will be described with reference to FIG. The second embodiment has the configuration of the first embodiment.
As shown in FIG. 4 , the straddle-type vehicle 1 includes an engine unit 11 and a catalyst deterioration diagnostic device 80 . The engine unit 11 includes an engine 20 , an exhaust passage portion 51 , a catalyst 53 , an upstream oxygen concentration sensor 76 and a downstream oxygen concentration sensor 77 . Although the cooling system of the engine 20 is a natural air cooling system in FIG. 4, other cooling systems may be used. Although the engine 20 is a four-stroke engine in FIG. 4, it may be a two-stroke engine. The position of the catalyst 53 in the exhaust passage portion 51 is not limited to the position shown in FIG.
　第２実施形態の触媒劣化診断装置８０は、例えばＥＣＵ（Electronic Control Unit）である。ＥＣＵは、エンジンユニット１１を制御する。ＥＣＵは、エンジンユニット１１の制御以外の鞍乗型車両１の制御を行ってもよい。
　鞍乗型車両では一般的に自動車と比較してエンジンの回転速度の範囲が広いこと等が理由で、鞍乗型車両１では、自動車と比較して、上流酸素濃度センサの出力信号に発生する突発的信号反転組の長さが長くなりやすい。そこで、第２実施形態では、鞍乗型車両１に搭載された触媒劣化診断装置８０が、触媒５３の劣化診断を行うときに、第１信号反転タイミングと第２信号反転タイミングとの間に信号無効期間を設ける。これにより、突発的信号反転組の長さが長くなりやすい鞍乗型車両１において触媒５３の劣化診断を行うときに、触媒５３の劣化診断が可能となる機会を多く確保することができる。 The catalyst deterioration diagnostic device 80 of the second embodiment is, for example, an ECU (Electronic Control Unit). The ECU controls the engine unit 11 . The ECU may perform control of the straddle-type vehicle 1 other than the control of the engine unit 11 .
Straddle-type vehicles generally have a wider range of engine rotation speeds than automobiles. The length of the sudden signal inversion group tends to be long. Therefore, in the second embodiment, when the catalyst deterioration diagnosis device 80 mounted on the straddle-type vehicle 1 diagnoses the deterioration of the catalyst 53, the signal is detected between the first signal inversion timing and the second signal inversion timing. Set an invalid period. As a result, when diagnosing deterioration of the catalyst 53 in the straddle-type vehicle 1 in which the length of the sudden signal inversion group tends to be long, it is possible to secure many opportunities for diagnosing deterioration of the catalyst 53 .
　＜第３実施形態＞
　本発明の第３実施形態の触媒劣化診断装置８０によって制御されるエンジンユニット１１について図５を用いて説明する。第３実施形態は、第１実施形態の構成を有する。第３実施形態は、第２実施形態の構成を有していてもよい。図５に示すように、エンジンユニット１１は、エンジン２０と、吸気ユニット４０と、排気ユニット５０を有する。図５のエンジン２０は、４ストローク式のエンジンである。 <Third Embodiment>
The engine unit 11 controlled by the catalyst deterioration diagnosis device 80 of the third embodiment of the invention will be described with reference to FIG. The third embodiment has the configuration of the first embodiment. The third embodiment may have the configuration of the second embodiment. As shown in FIG. 5, the engine unit 11 has an engine 20, an intake unit 40, and an exhaust unit 50. As shown in FIG. The engine 20 in FIG. 5 is a four-stroke engine.
　エンジン２０は、クランクケース２１と、シリンダボディ２２と、シリンダヘッド２３とを備えている。 The engine 20 includes a crankcase 21, a cylinder body 22, and a cylinder head 23.
　クランクケース２１は、クランク軸２６等を収容している。クランクケース２１には、エンジン回転速度センサ７１が設けられている。エンジン回転速度センサ７１は、クランク軸２６の回転速度、即ち、エンジン回転速度を検出する。エンジン回転速度とは、単位時間当たりのクランク軸２６の回転数のことである。 The crankcase 21 accommodates the crankshaft 26 and the like. An engine rotation speed sensor 71 is provided in the crankcase 21 . The engine rotation speed sensor 71 detects the rotation speed of the crankshaft 26, that is, the engine rotation speed. The engine speed is the number of revolutions of the crankshaft 26 per unit time.
　シリンダボディ２２には、少なくとも１つのシリンダ孔２２ａが形成されている。少なくとも１つのシリンダ孔２２ａの各々には、ピストン２８が摺動可能に収容されている。ピストン２８は、コネクティングロッド２９を介してクランク軸２６に連結されている。 At least one cylinder hole 22a is formed in the cylinder body 22. A piston 28 is slidably accommodated in each of the at least one cylinder hole 22a. Piston 28 is connected to crankshaft 26 via a connecting rod 29 .
　シリンダヘッド２３とシリンダ孔２２ａとピストン２８によって、燃焼室３０が形成される。エンジン２０は、少なくとも１つの燃焼室３０を有する。少なくとも１つの燃焼室３０の各々には、点火プラグ３１の先端部が配置されている。点火プラグ３１の先端部は、火花放電を発生させる。この火花放電によって、燃焼室３０内の混合気が点火される。点火プラグ３１は、点火コイル３２に接続されている。点火コイル３２は、点火プラグ３１の火花放電を生じさせるための電力を蓄える。 A combustion chamber 30 is formed by the cylinder head 23, the cylinder hole 22a and the piston 28. Engine 20 has at least one combustion chamber 30 . A tip portion of a spark plug 31 is arranged in each of the at least one combustion chambers 30 . The tip of the spark plug 31 generates spark discharge. This spark discharge ignites the air-fuel mixture in the combustion chamber 30 . The ignition plug 31 is connected to the ignition coil 32 . The ignition coil 32 stores electric power for generating spark discharge of the ignition plug 31 .
　燃焼室３０には、１つまたは２つの吸気ポート３３と１つまたは２つの排気ポート３４が形成されている。吸気ポート３３は、吸気弁３５によって開閉される。排気ポート３４は、排気弁３６によって開閉される。吸気弁３５および排気弁３６は、シリンダヘッド２３内に収容された動弁装置（図示せず）によって開閉駆動される。動弁装置は、クランク軸２６と連動して作動する。 One or two intake ports 33 and one or two exhaust ports 34 are formed in the combustion chamber 30 . The intake port 33 is opened and closed by an intake valve 35 . The exhaust port 34 is opened and closed by an exhaust valve 36 . The intake valve 35 and the exhaust valve 36 are driven to open and close by a valve train (not shown) housed in the cylinder head 23 . The valve train operates in conjunction with the crankshaft 26 .
　エンジンユニット１１は、吸気ポート３３と、大気に面する大気吸入口４１ｃとをつなぐ吸気通路部４１を有する。吸気通路部４１は、エンジン２０が有する全ての燃焼室３０に接続される。大気吸入口４１ｃから吸い込まれた空気は、吸気通路部４１内を吸気ポート３３に向かって流れる。吸気通路部４１の一部は、エンジン２０に形成されており、吸気通路部４１の残りの部分は、吸気ユニット４０に形成されている。吸気ユニット４０は、エンジン２０に接続された吸気管を有する。さらに、吸気ユニット４０は、少なくとも１つのインジェクタ４２と少なくとも１つのスロットル弁４５を有する。 The engine unit 11 has an intake passage portion 41 that connects the intake port 33 and an air intake port 41c facing the atmosphere. The intake passage portion 41 is connected to all the combustion chambers 30 of the engine 20 . The air sucked from the air intake port 41 c flows through the intake passage portion 41 toward the intake port 33 . A portion of the intake passage portion 41 is formed in the engine 20 , and the remaining portion of the intake passage portion 41 is formed in the intake unit 40 . The intake unit 40 has an intake pipe connected to the engine 20 . Furthermore, intake unit 40 has at least one injector 42 and at least one throttle valve 45 .
　エンジンユニット１１は、排気ポート３４と、大気に面する大気放出口６４ａとをつなぐ排気通路部５１を有する。排気通路部５１は、エンジン２０が有する全ての燃焼室３０に接続される。燃焼室３０で発生した排ガスは、排気ポート３４を介して排気通路部５１に排出される。排ガスは排気通路部５１内を大気放出口６４ａに向かって流れる。排気通路部５１の一部は、エンジン２０に形成されており、排気通路部５１の残りの部分は、排気ユニット５０に形成されている。排気ユニット５０は、エンジン２０に接続された排気管５２を有する。さらに、排気ユニット５０は、触媒５３とマフラー５４を有する。マフラー５４は、排ガスによる騒音を低減する装置である。マフラー５４は、排気通路部５１に含まれる。上流酸素濃度センサ７６および下流酸素濃度センサ７７は排気管５２に設けられている。上流酸素濃度センサ７６はエンジン２０に設けられてもよい。下流酸素濃度センサ７７はマフラー５４に設けられてもよい。燃焼室３０の数が複数の場合、複数の燃料室３０に対して１つの触媒５３が設けられてもよく、燃料室３０ごとに１つの触媒５３が設けられてもよく、複数の燃料室３０うちの２以上の燃料室３０ごとに１つの触媒５３が設けられてもよい。上流酸素濃度センサ７６は、触媒５３ごとに設けられてもよく、複数の触媒５３のいずれかに対して設けられてもよい。下流酸素濃度センサ７７は、触媒５３ごとに設けられてもよく、複数の触媒５３のいずれかに対して設けられてもよく、複数の触媒５３に対して設けられてもよい。エンジンユニット１１は、少なくとも１つの触媒５３とは別に、いずれかの触媒５３の上流または下流に配置されたサブ触媒を有してもよい。 The engine unit 11 has an exhaust passage portion 51 that connects the exhaust port 34 and the atmosphere discharge port 64a facing the atmosphere. The exhaust passage portion 51 is connected to all the combustion chambers 30 of the engine 20 . Exhaust gas generated in the combustion chamber 30 is discharged to the exhaust passage portion 51 through the exhaust port 34 . Exhaust gas flows through the exhaust passage portion 51 toward the atmosphere discharge port 64a. A portion of the exhaust passage portion 51 is formed in the engine 20 , and the remaining portion of the exhaust passage portion 51 is formed in the exhaust unit 50 . The exhaust unit 50 has an exhaust pipe 52 connected to the engine 20 . Furthermore, the exhaust unit 50 has a catalyst 53 and a muffler 54 . The muffler 54 is a device that reduces noise caused by exhaust gas. A muffler 54 is included in the exhaust passage portion 51 . An upstream oxygen concentration sensor 76 and a downstream oxygen concentration sensor 77 are provided in the exhaust pipe 52 . The upstream oxygen concentration sensor 76 may be provided on the engine 20 . A downstream oxygen concentration sensor 77 may be provided in the muffler 54 . When the number of combustion chambers 30 is plural, one catalyst 53 may be provided for the plural fuel chambers 30 , one catalyst 53 may be provided for each fuel chamber 30 , or the plural fuel chambers 30 may be provided for each fuel chamber 30 . One catalyst 53 may be provided for two or more of the fuel chambers 30 . The upstream oxygen concentration sensor 76 may be provided for each catalyst 53 or may be provided for any one of the plurality of catalysts 53 . The downstream oxygen concentration sensor 77 may be provided for each catalyst 53 , may be provided for any one of the plurality of catalysts 53 , or may be provided for the plurality of catalysts 53 . The engine unit 11 may have sub-catalysts arranged upstream or downstream of any of the catalysts 53 apart from the at least one catalyst 53 .
　インジェクタ４２は、吸気通路部４１に配置されている。インジェクタ４２は、吸気通路部４１内の空気に対して燃料を噴射する。これにより、吸気通路部４１を介して燃焼室３０に燃料が供給される。インジェクタ４２を、燃焼室３０に直接燃料が噴射されるように設けてもよい。１つの燃焼室３０に対して１つまたは２つのインジェクタ４２が設けられる。インジェクタ４２は、燃料ホース４３を介して燃料タンク１０に接続されている。燃料タンク１０の内部には、燃料ポンプ４４が配置されている。燃料ポンプ４４は、燃料タンク１０内の燃料を燃料ホース４３へと圧送する。第３実施形態において、燃料供給装置４６は、インジェクタ４２と燃料ポンプ４４とを有する。 The injector 42 is arranged in the intake passage portion 41 . The injector 42 injects fuel into the air inside the intake passage portion 41 . As a result, fuel is supplied to the combustion chamber 30 through the intake passage portion 41 . An injector 42 may be provided to inject fuel directly into the combustion chamber 30 . One or two injectors 42 are provided for one combustion chamber 30 . The injector 42 is connected to the fuel tank 10 via a fuel hose 43 . A fuel pump 44 is arranged inside the fuel tank 10 . The fuel pump 44 pumps the fuel in the fuel tank 10 to the fuel hose 43 . In the third embodiment, fuel supply device 46 has injector 42 and fuel pump 44 .
　スロットル弁４５は、吸気通路部４１に設けられる。スロットル弁４５は、インジェクタ４２よりも上流に配置される。１つの燃焼室３０に対して１つのスロットル弁４５が設けられる。スロットル弁４５は、スロットルワイヤを介して、アクセルグリップ（図示せず）に接続されている。ライダーがアクセルグリップを回動操作することによって、スロットル弁４５の開度が変更される。エンジンユニット１１は、スロットル弁４５の開度を検出するスロットル開度センサ（スロットルポジションセンサ）７３を有する。以下、スロットル弁４５の開度を、スロットル開度という。スロットル開度センサ７３は、スロットル弁４５の位置を検出することにより、スロットル開度を表す信号を出力する。なお、スロットル弁４５は、電子制御で開閉する電子スロットル弁であってもよい。この場合、スロットル開度センサ７３は、電子制御の信号に基づいて、スロットル開度を表す信号を出力してもよい。 The throttle valve 45 is provided in the intake passage portion 41 . The throttle valve 45 is arranged upstream of the injector 42 . One throttle valve 45 is provided for one combustion chamber 30 . The throttle valve 45 is connected to an accelerator grip (not shown) via a throttle wire. The degree of opening of the throttle valve 45 is changed by the rider rotating the accelerator grip. The engine unit 11 has a throttle opening sensor (throttle position sensor) 73 that detects the opening of the throttle valve 45 . Hereinafter, the opening degree of the throttle valve 45 will be referred to as the throttle opening degree. The throttle opening sensor 73 detects the position of the throttle valve 45 and outputs a signal representing the throttle opening. Note that the throttle valve 45 may be an electronic throttle valve that is electronically controlled to open and close. In this case, the throttle opening sensor 73 may output a signal representing the throttle opening based on the electronic control signal.
　第３実施形態において、触媒劣化診断装置８０は、エンジン回転速度センサ７１、スロットル開度センサ７３、上流酸素濃度センサ７６、下流酸素濃度センサ７７等の各種センサと接続されている。触媒劣化診断装置８０には、各種センサの信号が入力される。触媒劣化診断装置８０は、点火コイル３２、インジェクタ４２、燃料ポンプ４４等と接続されている。
　触媒劣化診断装置８０は、燃料供給量制御と点火時期制御を行う。上述の燃料量Ｈの制御は、燃料供給量制御に含まれる。触媒劣化診断装置８０は、燃料供給量制御において、インジェクタ４２および燃料ポンプ４４を制御する。触媒劣化診断装置８０は、インジェクタ４２による燃料噴射時間を制御することで、少なくとも１つの燃焼室３０に供給される燃料量Ｈを制御する。触媒劣化診断装置８０は、点火時期制御において、点火コイル３２を制御する。 In the third embodiment, the catalyst deterioration diagnosis device 80 is connected to various sensors such as an engine rotation speed sensor 71, a throttle opening sensor 73, an upstream oxygen concentration sensor 76, a downstream oxygen concentration sensor 77, and the like. Signals from various sensors are input to the catalyst deterioration diagnosis device 80 . The catalyst deterioration diagnostic device 80 is connected to the ignition coil 32, the injector 42, the fuel pump 44, and the like.
The catalyst deterioration diagnosis device 80 performs fuel supply amount control and ignition timing control. The above control of the fuel amount H is included in the fuel supply amount control. The catalyst deterioration diagnosis device 80 controls the injector 42 and the fuel pump 44 in controlling the fuel supply amount. The catalyst deterioration diagnosis device 80 controls the fuel amount H supplied to at least one combustion chamber 30 by controlling the fuel injection time of the injector 42 . The catalyst deterioration diagnosis device 80 controls the ignition coil 32 in ignition timing control.
　＜第４実施形態＞
　本発明の第４実施形態について図６（ａ）、（ｂ）および図７を用いて説明する。第４実施形態は、第１実施形態の構成を有する。第４実施形態は第２実施形態および第３実施施形態の少なくとも１つの構成を有していてもよい。
　第４実施形態において、触媒劣化診断装置８０は、図６（ａ）に示すフローに沿った処理を行う。図６（ａ）のフローが開始されたときの燃料量Ｈの制御は、通常の燃料量Ｈの制御である。燃料量Ｈの制御が通常の燃料量Ｈの制御であるとき、および、後述するステップＳ１１～ステップＳ１７の処理が行われているとき、触媒劣化診断装置８０は、上流酸素濃度センサ７６の出力信号に基づいて燃料量Ｈを制御する。ここで、上流酸素濃度センサ７６の出力信号に基づいた燃料量Ｈの制御の詳細について図７に示す例を用いて説明する。上流酸素濃度センサ７６の出力信号がリーン状態に切り換わってから、時間Ｗｓａが経過したときに、燃料量ＨがΔＳａ増加する。その後、上流酸素濃度センサ７６の出力信号がリーン状態である間、燃料量Ｈは時間間隔ωａ毎にΔＡずつ徐々に増加する。さらに、上流酸素濃度センサ７６の出力信号がリッチ状態に切り換わってから、時間Ｗｓｂが経過するまでの期間も、燃料量Ｈは時間間隔ωａ毎にΔＡずつ徐々に増加する。上流酸素濃度センサ７６の出力信号がリッチ状態に切り換わってから、時間Ｗｓｂが経過したときに、燃料量ＨがΔＳｂ減少する。その後、上流酸素濃度センサ７６の出力信号がリッチ状態である間、燃料量Ｈは時間間隔ωｂ毎にΔＢずつ徐々に減少する。さらに、上流酸素濃度センサ７６の出力信号がリーン状態に切り換わってから、時間Ｗｓａが経過するまでの期間も、燃料量Ｈは時間間隔ωｂ毎にΔＢずつ徐々に減少する。ΔＳｂはΔＳａと同じであってもよいし、ΔＳａと異なっていてもよい。時間間隔ωｂは時間間隔ωａと同じであってもよいし、時間間隔ωａと異なっていてもよい。ΔＢはΔＡと同じであってもよいし、ΔＡと異なっていてもよい。時間Ｗｓｂは、時間Ｗｓａと同じであってもよいし、時間Ｗｓａと異なっていてもよい。 <Fourth Embodiment>
A fourth embodiment of the present invention will be described with reference to FIGS. 6(a), (b) and 7. FIG. The fourth embodiment has the configuration of the first embodiment. The fourth embodiment may have at least one configuration of the second and third embodiments.
In the fourth embodiment, the catalyst deterioration diagnosis device 80 performs processing according to the flow shown in FIG. 6(a). Control of the fuel amount H when the flow of FIG. 6(a) is started is normal fuel amount H control. When the control of the fuel amount H is normal control of the fuel amount H, and when the processing of steps S11 to S17 described later is being performed, the catalyst deterioration diagnosis device 80 detects the output signal of the upstream oxygen concentration sensor 76. The fuel amount H is controlled based on. Details of the control of the fuel amount H based on the output signal of the upstream oxygen concentration sensor 76 will now be described using the example shown in FIG. When the time Wsa has passed since the output signal of the upstream oxygen concentration sensor 76 switched to the lean state, the fuel amount H increases by ΔSa. After that, while the output signal of the upstream oxygen concentration sensor 76 is lean, the fuel amount H gradually increases by ΔA at each time interval ωa. Furthermore, during the period from when the output signal of the upstream oxygen concentration sensor 76 switches to the rich state until the time Wsb elapses, the fuel amount H gradually increases by ΔA at each time interval ωa. When the time Wsb elapses after the output signal of the upstream oxygen concentration sensor 76 switches to the rich state, the fuel amount H decreases by ΔSb. After that, while the output signal of the upstream oxygen concentration sensor 76 is in the rich state, the fuel amount H gradually decreases by ΔB at each time interval ωb. Furthermore, during the period from when the output signal of the upstream oxygen concentration sensor 76 switches to the lean state to when the time Wsa elapses, the fuel amount H gradually decreases by ΔB at each time interval ωb. ΔSb may be the same as ΔSa, or may be different from ΔSa. The time interval ωb may be the same as the time interval ωa or may be different from the time interval ωa. ΔB may be the same as ΔA or may be different from ΔA. Time Wsb may be the same as time Wsa, or may be different from time Wsa.
　図６（ａ）のフローについて詳細に説明すると、触媒劣化診断装置８０は、まず、触媒劣化診断条件を満たすか否かを判断する（ステップＳ１１）。触媒劣化診断条件は、触媒５３の劣化診断前に満たせばよい第１条件と、触媒５３の劣化診断前および触媒５３の劣化診断中の両方において満たす必要のある第２条件とを含む。
　第１条件は、例えば、エンジン２０の始動から一定時間が経過したという条件を含む。また、第１条件は、例えば、燃料量の増加／減少の反転周期が所定の範囲にあるという条件を含む。第１条件は、これらの条件のうち少なくとも１つの条件を含んでいてもよい。
　第２条件は、例えば、上流酸素濃度センサ７６および下流酸素濃度センサ７７の両方が活性化しているという条件を含む。第２条件は、例えば、触媒５３が活性化しているという条件を含む。触媒劣化診断装置８０は、例えば、エンジン始動後の経過時間および／または、累積エンジン回転数、エンジン温度、外気温度などから酸素濃度センサ７６、７７または触媒５３が活性化しているか否かを判断してもよい。また、第２条件は、例えば、エンジン２０の回転速度およびエンジン２０の負荷が触媒５３の劣化診断に適した領域内にあるという条件を含む。また、第２条件は、例えば、エンジン２０に供給される空気の空気量の変化量および空気圧の変化量の両方が閾値以下であるという条件を含む。なお、第２条件は、これらの条件のうち少なくとも１つの条件を含んでいてもよい。
　また、触媒劣化診断装置８０は、この後のステップＳ１３～Ｓ１７の処理を実行するときに、これらの処理と並行して第２条件を満たすか否かを判断する。
　触媒劣化診断装置８０は、触媒劣化診断条件を満たさないと判断したときには（ステップＳ１１：ＮＯ）、燃料量Ｈの制御を通常の燃料量Ｈの制御に維持する。
　触媒劣化診断装置８０は、触媒劣化診断条件を満たすと判断したしたときに（ステップＳ１１：ＹＥＳ）、前回の触媒５３の劣化診断を途中で終了したか否かを判定する（ステップＳ１２）。触媒劣化診断装置８０は、例えば、触媒５３の劣化診断の途中でエンジン２０が停止された場合に、触媒５３の劣化診断を途中で終了する。また、触媒劣化診断装置８０は、例えば、上流酸素濃度センサ７６の出力信号に基づく燃料量Ｈの制御が行われなくなった場合に、触媒５３の劣化診断を途中で終了する。また、触媒劣化診断装置８０は、例えば、触媒５３の劣化診断の途中で、上記第２条件を満たさなくなった場合に、触媒５３の劣化診断を途中で終了する。また、触媒劣化診断装置８０は、例えば、触媒５３の劣化診断の途中で、信号反転間隔が触媒劣化診断間隔となるようにエンジン２０を運転することができなくなることによって、燃料量Ｈの増加／減少の反転周期が極端に長くなった場合に、触媒５３の劣化診断を途中で終了する。
　なお、触媒劣化診断装置８０は、これらの場合のうち少なくとも１つの場合に、触媒５３の劣化診断を途中で終了してもよい。
　前回の触媒５３の劣化診断が途中で終了してない場合には（ステップＳ１２：ＮＯ）、触媒劣化診断装置８０は、ステップＳ１３およびステップＳ１４の処理を行ってからステップＳ１５に進む。前回の触媒５３の劣化診断が途中で終了していた場合には（ステップＳ１２：ＹＥＳ）、触媒劣化診断装置８０は、そのままステップＳ１５に進む。
　ステップＳ１３おいて、触媒劣化診断装置８０は、燃料量Ｈの制御を、通常の燃料量Ｈの制御から、燃料量Ｈの増加／減少の反転の周期を測定するための燃料量Ｈの制御に切り換える。触媒劣化診断装置８０は、例えば図７に示すωａ、ωｂ、ΔＡ、ΔＳａ、ΔＢ、ΔＳｂ、Ｗｓａ、Ｗｓｂのうち少なくとも１つを変更して、燃料量Ｈの制御を、燃料量Ｈの増加／減少の反転の周期を測定するための燃料量Ｈの制御に切り換える。なお、ステップＳ１３および後述のステップＳ１５において燃料量Ｈの制御を切り換えるときには、吸気量の制御は変更しない。したがって、ステップＳ１３および後述のステップＳ１５において燃料量Ｈの制御を切り換えても、エンジン２０の回転速度は大きく変化しない。燃料量Ｈの増加／減少の反転の周期を測定するための燃料量Ｈの制御において、時間Ｗｓａと時間Ｗｓｂは例えば反転判定時間Ｒ１と反転判定時間Ｒ２である。
　ステップＳ１４において、触媒劣化診断装置８０は、燃料量Ｈの増加／減少の反転の周期の測定を行う。
　ステップＳ１５において、触媒劣化診断装置８０は、燃料量Ｈの制御を、通常の燃料量Ｈの制御または燃料量Ｈの増加／減少の反転の周期を測定するための燃料量Ｈの制御から、触媒５３の劣化診断のための燃料量Ｈの制御に切り換える。触媒劣化診断装置８０は、ステップＳ１４で測定した燃料量Ｈの増加／減少の反転の周期に基づいて、例えば時間Ｗｓａ、Ｗｓｂを変更して、エンジン２０を信号反転間隔が触媒劣化診断間隔となるように運転させる。より具体的には、例えば、時間Ｗｓａは、反転判定時間Ｒ１に０より大きい追加時間Ｑ１を足し合わせた時間に変更され、時間Ｗｓｂは、反転判定時間Ｒ２に０より大きい追加時間Ｑ２を足し合わせた時間に変更される。なお、前回の触媒５３の劣化診断が途中で終了していた場合には、触媒劣化診断装置８０は、前回の触媒５３の劣化の診断時におけるステップＳ１４で測定した燃料量Ｈの増加／減少の反転の周期に基づいて、例えば時間Ｗｓａ、Ｗｓｂを変更して、燃料量Ｈの制御を信号反転間隔が触媒劣化診断間隔となるような燃料量Ｈの制御にする。また、ステップＳ１５において、触媒劣化診断装置８０は、第１実施形態で説明したのと同様に、第１信号反転タイミングと第２信号反転タイミングとの間に信号無効期間を設ける。
　続いて、触媒劣化診断装置８０は、触媒５３の劣化診断を行う（ステップＳ１６）。
　ステップＳ１６の触媒５３の劣化診断の完了後、触媒劣化診断装置８０は、燃料量Ｈの制御を通常の燃料量Ｈの制御に切り換え（ステップＳ１７）、ステップＳ１１に戻る。
　ここで、図６（ｂ）は、図６（ａ）のフローに沿って処理を行ったときの燃料量Ｈの変化の一例を示す図である。この例では、触媒劣化診断装置８０は、タイミングＴａに、燃料量Ｈの制御を、燃料量Ｈの増加／減少の反転の周期を測定するための燃料量Ｈの制御に切り換える。そして、触媒劣化診断装置８０は、タイミングＴａの後のタイミングＴｂに、燃料量Ｈの制御を触媒５３の劣化診断のための燃料量Ｈの制御に切り換える。また、触媒劣化診断装置８０は、タイミングＴｂの後のタイミングＴｃに、燃料量Ｈの制御を通常の燃料量Ｈの制御に切り換える。タイミングＴａ、タイミングＴｂおよびタイミングＴｃに、信号反転間隔が変更される。 6A will be described in detail. First, the catalyst deterioration diagnosis device 80 determines whether or not the conditions for catalyst deterioration diagnosis are satisfied (step S11). The catalyst deterioration diagnosis conditions include a first condition that should be satisfied before the deterioration diagnosis of the catalyst 53 and a second condition that must be satisfied both before the deterioration diagnosis of the catalyst 53 and during the deterioration diagnosis of the catalyst 53 .
The first condition includes, for example, the condition that a certain period of time has elapsed since the engine 20 was started. Further, the first condition includes, for example, a condition that the reversal cycle of increase/decrease of the fuel amount is within a predetermined range. The first condition may include at least one of these conditions.
The second condition includes, for example, the condition that both the upstream oxygen concentration sensor 76 and the downstream oxygen concentration sensor 77 are activated. The second condition includes, for example, the condition that the catalyst 53 is activated. The catalyst deterioration diagnostic device 80 determines whether or not the oxygen concentration sensors 76 and 77 or the catalyst 53 is activated from, for example, the elapsed time after the engine is started and/or the cumulative engine speed, the engine temperature, the outside air temperature, and the like. may Further, the second condition includes, for example, the condition that the rotational speed of the engine 20 and the load of the engine 20 are within ranges suitable for the degradation diagnosis of the catalyst 53 . Further, the second condition includes, for example, a condition that both the amount of change in the amount of air supplied to the engine 20 and the amount of change in air pressure are equal to or less than a threshold. Note that the second condition may include at least one of these conditions.
Further, when the catalyst deterioration diagnosis device 80 executes the processes of steps S13 to S17 thereafter, it determines whether or not the second condition is satisfied in parallel with these processes.
When the catalyst deterioration diagnosis device 80 determines that the catalyst deterioration diagnosis condition is not satisfied (step S11: NO), the control of the fuel amount H is maintained at the normal fuel amount H control.
When it is determined that the conditions for diagnosing catalyst deterioration are satisfied (step S11: YES), the catalyst deterioration diagnosis device 80 determines whether or not the previous deterioration diagnosis of the catalyst 53 was terminated halfway (step S12). For example, when the engine 20 is stopped during the deterioration diagnosis of the catalyst 53, the catalyst deterioration diagnosis device 80 ends the deterioration diagnosis of the catalyst 53 in the middle. Further, the catalyst deterioration diagnosis device 80 ends the deterioration diagnosis of the catalyst 53 halfway, for example, when the control of the fuel amount H based on the output signal of the upstream oxygen concentration sensor 76 is no longer performed. Further, the catalyst deterioration diagnosis device 80 ends the deterioration diagnosis of the catalyst 53 in the middle, for example, when the second condition is no longer satisfied during the deterioration diagnosis of the catalyst 53 . In addition, the catalyst deterioration diagnosis device 80 may not be able to operate the engine 20 so that the signal inversion interval is equal to the catalyst deterioration diagnosis interval during the deterioration diagnosis of the catalyst 53, for example. If the reversal period of decrease becomes extremely long, the deterioration diagnosis of the catalyst 53 is terminated halfway.
In at least one of these cases, the catalyst deterioration diagnosis device 80 may end the deterioration diagnosis of the catalyst 53 halfway.
If the previous diagnosis of deterioration of the catalyst 53 has not ended halfway (step S12: NO), the catalyst deterioration diagnosis device 80 performs the processes of steps S13 and S14, and then proceeds to step S15. If the previous deterioration diagnosis of the catalyst 53 was terminated halfway (step S12: YES), the catalyst deterioration diagnosis device 80 directly proceeds to step S15.
In step S13, the catalyst deterioration diagnosis device 80 changes the control of the fuel amount H from the normal control of the fuel amount H to the control of the fuel amount H for measuring the cycle of reversing the increase/decrease of the fuel amount H. switch. The catalyst deterioration diagnosis device 80 changes, for example, at least one of ωa, ωb, ΔA, ΔSa, ΔB, ΔSb, Wsa, and Wsb shown in FIG. Switch to control of the fuel amount H for measuring the period of reversal of decrease. Note that when the control of the fuel amount H is switched in step S13 and step S15 described later, the control of the intake air amount is not changed. Therefore, even if the control of the fuel amount H is switched in step S13 and step S15, which will be described later, the rotation speed of the engine 20 does not change significantly. In the control of the fuel amount H for measuring the period of reversal of the increase/decrease of the fuel amount H, the time Wsa and the time Wsb are, for example, the reversal determination time R1 and the reversal determination time R2.
In step S14, the catalyst deterioration diagnosis device 80 measures the cycle of reversal of the increase/decrease of the fuel amount H. FIG.
In step S15, the catalyst deterioration diagnosis device 80 changes the control of the fuel amount H from the normal control of the fuel amount H or the control of the fuel amount H for measuring the cycle of reversal of the increase/decrease of the fuel amount H to the catalyst Switching to control of the fuel amount H for deterioration diagnosis of 53 . The catalyst deterioration diagnosis device 80 changes, for example, the times Wsa and Wsb based on the period of reversal of the increase/decrease of the fuel amount H measured in step S14, and the signal inversion interval for the engine 20 becomes the catalyst deterioration diagnosis interval. drive like this. More specifically, for example, the time Wsa is changed to a time obtained by adding an additional time Q1 greater than 0 to the reversal determination time R1, and the time Wsb is changed to a time obtained by adding an additional time Q2 greater than 0 to the reversal determination time R2. changed in time. Note that if the previous deterioration diagnosis of the catalyst 53 was terminated in the middle, the catalyst deterioration diagnosis device 80 determines whether the increase/decrease of the fuel amount H measured in step S14 at the time of the previous deterioration diagnosis of the catalyst 53 is determined. For example, the times Wsa and Wsb are changed based on the reversal period, and the control of the fuel amount H is such that the signal reversal interval becomes the catalyst deterioration diagnosis interval. Further, in step S15, the catalyst deterioration diagnosis device 80 provides a signal invalid period between the first signal inversion timing and the second signal inversion timing, as described in the first embodiment.
Subsequently, the catalyst deterioration diagnosis device 80 diagnoses the deterioration of the catalyst 53 (step S16).
After completing the deterioration diagnosis of the catalyst 53 in step S16, the catalyst deterioration diagnosis device 80 switches the fuel amount H control to normal fuel amount H control (step S17), and returns to step S11.
Here, FIG. 6(b) is a diagram showing an example of changes in the fuel amount H when the process is performed along the flow of FIG. 6(a). In this example, the catalyst deterioration diagnosis device 80 switches control of the fuel amount H to control of the fuel amount H for measuring the cycle of reversal of increase/decrease of the fuel amount H at the timing Ta. Then, the catalyst deterioration diagnosis device 80 switches the control of the fuel amount H to the control of the fuel amount H for diagnosing the deterioration of the catalyst 53 at the timing Tb after the timing Ta. Further, the catalyst deterioration diagnosis device 80 switches the control of the fuel amount H to the normal control of the fuel amount H at the timing Tc after the timing Tb. The signal inversion interval is changed at timing Ta, timing Tb, and timing Tc.
　第４実施形態において、燃料量Ｈの制御が通常の燃料量Ｈの制御であるときには、第１信号反転タイミングと第２信号反転タイミングとの間に信号無効期間を設けない。これにより、触媒５３の劣化診断を行わないときの燃料量Ｈの制御を簡単にすることができる。 In the fourth embodiment, when the control of the fuel amount H is normal control of the fuel amount H, no signal invalid period is provided between the first signal inversion timing and the second signal inversion timing. This makes it possible to simplify the control of the fuel amount H when the deterioration diagnosis of the catalyst 53 is not performed.
　第４実施形態において、燃料量Ｈの制御が燃料量Ｈの増加／減少の反転の周期を測定するための燃料量Ｈの制御のときに、信号無効期間と同様の期間を設けてもよい。すなわち、燃料量Ｈの制御が燃料量Ｈの増加／減少の反転の周期を測定するための燃料量Ｈの制御であるときに、第１信号反転タイミングと第２信号反転タイミングとの間の期間に、信号無効期間と同様の期間を設けてもよい。そして、この設けた期間に、上流酸素濃度センサ７６の出力信号に所定の長さよりも長い突発的信号反転組が発生しても、当該信号反転組を無視して燃料量Ｈの増加／減少を反転させないように制御してもよい。これにより、燃料量Ｈの増加／減少の反転の周期を測定するための燃料量Ｈの制御を行うときの信号反転間隔の乱れを抑制できる。そのため、燃料量Ｈの増加／減少の反転の周期の測定の精度を向上できる。その結果、触媒５３の劣化の診断の精度を向上できる。なお、燃料量Ｈの制御が燃料量Ｈの増加／減少の反転の周期を測定するための燃料量Ｈの制御のときに設ける信号無効期間と同様の期間の長さは、燃料量Ｈの制御が触媒５３の劣化診断のための燃料量Ｈの制御のときに設ける信号無効期間の長さと同じであってもよいし異なっていてもよい。　第４実施形態において、燃料量Ｈの制御が燃料量の増加／減少の反転の周期を測定するための燃料量Ｈの制御であるときに、信号無効期間を設けなくてもよい。これにより、触媒５３の劣化診断を行わないときの燃料量の制御をより簡単にすることができる。 In the fourth embodiment, a period similar to the signal invalid period may be provided when the control of the fuel amount H is for measuring the cycle of reversing the increase/decrease of the fuel amount H. That is, when the control of the fuel amount H is the control of the fuel amount H for measuring the cycle of reversing the increase/decrease of the fuel amount H, the period between the first signal inversion timing and the second signal inversion timing may be provided with a period similar to the signal invalid period. Even if a sudden set of signal inversions longer than a predetermined length occurs in the output signal of the upstream oxygen concentration sensor 76 during this provided period, the set of signal inversions is ignored and the fuel amount H is increased/decreased. You may control so that it may not be reversed. As a result, it is possible to suppress the disturbance of the signal inversion interval when controlling the fuel amount H for measuring the period of reversal of the increase/decrease of the fuel amount H. FIG. Therefore, it is possible to improve the accuracy of measurement of the cycle of reversal of the increase/decrease of the fuel amount H. FIG. As a result, the accuracy of diagnosing deterioration of the catalyst 53 can be improved. It should be noted that the length of the period similar to the signal invalid period provided when controlling the fuel amount H for measuring the cycle of reversing the increase/decrease of the fuel amount H is determined by the control of the fuel amount H. may be the same as or different from the length of the signal invalid period provided when controlling the fuel amount H for diagnosing the deterioration of the catalyst 53 . In the fourth embodiment, when the control of the fuel amount H is the control of the fuel amount H for measuring the cycle of reversing the increase/decrease of the fuel amount, it is not necessary to provide the signal invalid period. This makes it possible to further simplify the control of the fuel amount when the deterioration diagnosis of the catalyst 53 is not performed.
　第４実施形態において、エンジン２０が運転されているときに常に信号無効期間を設けるように制御してもよい。 In the fourth embodiment, control may be performed so that the signal invalid period is always provided while the engine 20 is running.
　＜第５実施形態＞
　本発明の第５実施形態について図７および図８を用いて説明する。第５実施形態は、第１実施形態の構成を有する。第５実施形態は、第２～第４実施形態の少なくとも１つの構成を有していてもよい。第５実施形態において、触媒劣化診断装置８０は、燃料量Ｈの制御として、通常の燃料量Ｈの制御が開始されたときに図８のフローに沿った処理を開始し、燃料量Ｈの制御が通常の燃料量Ｈの制御である間、この処理を継続する。なお、第５実施形態における通常の燃料量Ｈの制御は、第４実施形態における通常の燃料量Ｈの制御と同様に、燃料量Ｈの増加／減少の反転の周期を測定するための燃料量Ｈの制御、および、触媒５３の劣化診断のための燃料量Ｈの制御のいずれとも異なる。通常の燃料量Ｈの制御において、触媒劣化診断装置８０は、上流酸素濃度センサ７６の出力信号に基づいて燃料量Ｈを制御する。第５実施形態において、燃料量Ｈの制御が通常の燃料量Ｈの制御で開始されたときには、信号無効期間の設定が解除された状態となっている。信号無効期間の設定が解除された状態とは、第１信号反転タイミングと第２信号反転タイミングとの間に信号無効期間を設けない状態のことである。 <Fifth Embodiment>
A fifth embodiment of the present invention will be described with reference to FIGS. 7 and 8. FIG. The fifth embodiment has the configuration of the first embodiment. The fifth embodiment may have at least one configuration of the second to fourth embodiments. In the fifth embodiment, the catalyst deterioration diagnosis device 80, as the control of the fuel amount H, starts the processing along the flow of FIG. is the normal fuel amount H control, this process is continued. The control of the normal fuel amount H in the fifth embodiment is similar to the control of the normal fuel amount H in the fourth embodiment. It differs from both the control of H and the control of the fuel amount H for diagnosing deterioration of the catalyst 53 . In normal control of the fuel amount H, the catalyst deterioration diagnosis device 80 controls the fuel amount H based on the output signal of the upstream oxygen concentration sensor 76 . In the fifth embodiment, when control of the fuel amount H is started with normal control of the fuel amount H, the setting of the signal invalid period is cancelled. A state in which the setting of the signal invalid period is canceled means a state in which no signal invalid period is provided between the first signal inversion timing and the second signal inversion timing.
　図８のフローについて具体的に説明すると、触媒劣化診断装置８０は、まず、触媒劣化診断条件を満たすか否かを判定する（ステップＳ２１）。触媒劣化診断条件とは、例えば、エンジン２０の始動から一定時間が経過したという条件、および／または、前回の触媒５３の劣化診断から一定時間が経過したという条件などである。触媒劣化診断条件を満たさない場合（ステップＳ２１：ＮＯ）、触媒劣化診断装置８０は、信号無効期間の設定が解除された状態を維持する。触媒劣化診断条件を満たす場合（ステップＳ２１：ＹＥＳ）、触媒劣化診断装置８０は、燃料量Ｈの制御が所定条件を満たすか否かを判定する（ステップＳ２２）。
　ステップＳ２２の所定条件とは、信号反転間隔が触媒劣化診断間隔となるようにエンジン２０が運転されているときの条件であり、図７のωａ、ωｂ、ΔＡ、ΔＳａ、ΔＢ、ΔＳｂ、Ｗｓａ、Ｗｓｂのうち少なくとも１つについての条件を含む。なお、燃料量Ｈの制御が所定条件を満たすとき、時間Ｗｓａと時間Ｗｓｂは例えば反転判定時間Ｒ１と反転判定時間Ｒ２である。すなわち、時間Ｗｓａは、反転判定時間Ｒ１に０である追加時間Ｑ１を足し合わせた時間であり、時間Ｗｓｂは、反転判定時間Ｒ２に０である追加時間Ｑ２を足し合わせた時間である。
　燃料量Ｈの制御が所定条件を満たしていない場合には（ステップＳ２２：ＮＯ）、触媒劣化診断装置８０は、ステップＳ２１に戻り、信号無効期間の設定が解除された状態を維持する。燃料量Ｈの制御が所定条件を満たす場合（ステップＳ２２：ＹＥＳ）、触媒劣化診断装置８０は信号無効期間を設定する（ステップＳ２３）。すなわち、触媒劣化診断装置８０は、第１実施形態で説明したのと同様に、第１信号反転タイミングと第２信号反転タイミングとの間に信号無効期間を設ける。続いて、触媒劣化診断装置８０は、第１実施形態で説明したのと同様に、触媒５３の劣化診断を行う（ステップＳ２４）。そして、触媒５３の劣化診断の完了後、触媒劣化診断装置８０は、信号無効期間の設定を解除し（ステップＳ２５）、ステップＳ２１に戻る。
　第５実施形態において、触媒劣化診断装置８０が上記のように処理を行うことにより、信号反転間隔が触媒劣化診断間隔となるようにエンジン２０が運転されているとき以外には、信号無効期間を設けないように制御される。これにより、触媒５３の劣化診断を行わないときの燃料量Ｈの制御を簡単にすることができる。 Specifically, the flow of FIG. 8 will be described. First, the catalyst deterioration diagnosis device 80 determines whether or not conditions for catalyst deterioration diagnosis are satisfied (step S21). The conditions for diagnosing catalyst deterioration include, for example, a condition that a certain period of time has elapsed since the start of the engine 20 and/or a condition that a certain period of time has elapsed since the previous deterioration diagnosis of the catalyst 53 . If the catalyst deterioration diagnosis condition is not satisfied (step S21: NO), the catalyst deterioration diagnosis device 80 maintains the state in which the setting of the signal invalid period is canceled. If the catalyst deterioration diagnosis condition is satisfied (step S21: YES), the catalyst deterioration diagnosis device 80 determines whether the control of the fuel amount H satisfies a predetermined condition (step S22).
The predetermined condition in step S22 is a condition when the engine 20 is operated such that the signal inversion interval is equal to the catalyst deterioration diagnosis interval. Includes conditions for at least one of Wsb. Note that when the control of the fuel amount H satisfies a predetermined condition, the time Wsa and the time Wsb are, for example, the reversal determination time R1 and the reversal determination time R2. That is, the time Wsa is the time obtained by adding the additional time Q1 of 0 to the reversal determination time R1, and the time Wsb is the time obtained by adding the additional time Q2 of 0 to the reversal determination time R2.
If the control of the fuel amount H does not satisfy the predetermined condition (step S22: NO), the catalyst deterioration diagnosis device 80 returns to step S21 and maintains the state in which the setting of the signal invalid period is canceled. If the control of the fuel amount H satisfies the predetermined condition (step S22: YES), the catalyst deterioration diagnostic device 80 sets the signal invalid period (step S23). That is, the catalyst deterioration diagnosis device 80 provides a signal invalid period between the first signal inversion timing and the second signal inversion timing, as described in the first embodiment. Subsequently, the catalyst deterioration diagnosis device 80 diagnoses deterioration of the catalyst 53 in the same manner as described in the first embodiment (step S24). After completing the deterioration diagnosis of the catalyst 53, the catalyst deterioration diagnosis device 80 cancels the setting of the signal invalid period (step S25), and returns to step S21.
In the fifth embodiment, the catalyst deterioration diagnosis device 80 performs the processing as described above, so that the signal ineffective period is set to the catalyst deterioration diagnosis interval except when the engine 20 is operated such that the signal inversion interval is the catalyst deterioration diagnosis interval. It is controlled not to set. This makes it possible to simplify the control of the fuel amount H when the deterioration diagnosis of the catalyst 53 is not performed.
　第５実施形態において、触媒劣化診断条件を満たし、且つ、燃料量Ｈの制御が所定条件を満たす場合に信号無効期間を設定したが、これには限られない。例えば、燃料量Ｈの制御が所定条件を満たしているときに、触媒劣化診断条件を満たしているか否かによらず信号無効期間を設定し、信号無効期間が設定されている状態で触媒劣化診断条件を満たしたときに、触媒の劣化診断を行ってもよい。 In the fifth embodiment, the signal invalid period is set when the catalyst deterioration diagnosis condition is satisfied and the control of the fuel amount H satisfies the predetermined condition, but it is not limited to this. For example, when the control of the fuel amount H satisfies a predetermined condition, the signal invalid period is set regardless of whether or not the catalyst deterioration diagnosis condition is met, and the catalyst deterioration diagnosis is performed in the state in which the signal invalid period is set. When the conditions are satisfied, the deterioration diagnosis of the catalyst may be performed.
　第５実施形態において、触媒劣化診断装置は、信号反転間隔が触媒劣化診断間隔となるようにエンジン２０が運転されているとき以外には、信号無効期間を設けないように制御したが、エンジン２０が運転されているときに常に信号無効期間を設けるように制御してもよい。 In the fifth embodiment, the catalyst deterioration diagnosis device performs control so that the signal invalid period is not provided except when the engine 20 is operated so that the signal inversion interval becomes the catalyst deterioration diagnosis interval. may be controlled so as to always provide a signal invalid period when the is in operation.
　＜第６実施形態＞
　本発明の第６実施形態について図９（ａ）、（ｂ）を用いて説明する。第６実施形態は、第１実施形態の構成を有する。第６実施形態は、第２～第５実施形態の少なくとも１つの構成を有していてもよい。第１実施形態で説明したように、触媒劣化診断装置８０は、信号反転間隔が触媒５３の劣化診断に適した触媒劣化診断間隔となっているときに、触媒５３の劣化診断を行う。また、第６実施形態において、触媒劣化診断装置８０は、信号無効期間を、エンジン２０の運転状態に応じて異なった長さに設定するように制御する。エンジン２０の運転状態に応じて異なる長さとは、例えば、エンジン２０の回転速度および／またはエンジン２０の負荷等に応じて異なる長さである。また、エンジン２０の運転状態に応じて触媒劣化診断間隔は変更される。例えば、エンジン２０の運転状態に応じて反転判定期間Ｒ１、Ｒ２が変更されることで触媒劣化診断間隔Ｗ１、Ｗ２が変更されてもよい。例えば、エンジン２０の運転状態が、図９（ａ）に示すように、触媒劣化診断間隔Ｗ１がＷ１ａであり、触媒劣化診断間隔Ｗ２がＷ２ａとなるような運転状態となっているときに、触媒劣化診断装置８０は、信号無効期間Ｍ１の長さをＮ１ａに設定し、信号無効期間Ｍ２の長さをＮ２ａに設定する。図９（ｂ）は、図９（ａ）とエンジン２０の運転状態が異なる場合を示す。エンジン２０の運転状態が、図９（ｂ）に示すように触媒劣化診断間隔Ｗ１がＷ１ａよりも短いＷ１ｂとなり、触媒劣化診断間隔Ｗ２がＷ２ａよりも短いＷ２ｂとなるような運転状態となっているときに、触媒劣化診断装置８０は、信号無効期間Ｍ１の長さをＮ１ａよりも短いＮ１ｂに設定し、信号無効期間Ｍ２の長さをＮ２ａよりも短いＮ２ｂに設定する。すなわち、第６実施形態では、エンジン２０の運転状態によって変わる触媒劣化診断間隔に応じて、信号無効期間の長さを異なった長さに設定する。
　なお、エンジン２０の運転状態に応じて触媒劣化診断間隔が変更される場合であっても、エンジン２０の運転状態が異なる２つのケースにおいて、必ずしも触媒劣化診断間隔が異なるとは限らず、触媒劣化診断間隔が同じになる場合がある。エンジン２０の運転状態が異なり、触媒劣化診断間隔が同じである２つのケースにおいて、信号無効期間の長さはエンジン２０の運転状態に応じて異なっていてもよく、同じであってもよい。 <Sixth Embodiment>
A sixth embodiment of the present invention will be described with reference to FIGS. The sixth embodiment has the configuration of the first embodiment. The sixth embodiment may have at least one configuration of the second to fifth embodiments. As described in the first embodiment, the catalyst deterioration diagnosis device 80 performs deterioration diagnosis of the catalyst 53 when the signal inversion interval is a catalyst deterioration diagnosis interval suitable for deterioration diagnosis of the catalyst 53 . Further, in the sixth embodiment, the catalyst deterioration diagnosis device 80 controls the signal invalid period to be set to different lengths according to the operating state of the engine 20 . The length that varies depending on the operating state of the engine 20 is, for example, a length that varies depending on the rotational speed of the engine 20 and/or the load of the engine 20 or the like. Further, the catalyst deterioration diagnosis interval is changed according to the operating state of the engine 20 . For example, the catalyst deterioration diagnosis intervals W1 and W2 may be changed by changing the reversal determination periods R1 and R2 according to the operating state of the engine 20 . For example, when the operating state of the engine 20 is such that the catalyst deterioration diagnosis interval W1 is W1a and the catalyst deterioration diagnosis interval W2 is W2a, as shown in FIG. The deterioration diagnosis device 80 sets the length of the signal invalid period M1 to N1a, and sets the length of the signal invalid period M2 to N2a. FIG. 9(b) shows a case where the operating state of the engine 20 is different from that in FIG. 9(a). As shown in FIG. 9B, the operating state of the engine 20 is such that the catalyst deterioration diagnosis interval W1 is W1b, which is shorter than W1a, and the catalyst deterioration diagnosis interval W2 is W2b, which is shorter than W2a. Sometimes, the catalyst deterioration diagnosis device 80 sets the length of the signal invalid period M1 to N1b, which is shorter than N1a, and sets the length of the signal invalid period M2 to N2b, which is shorter than N2a. That is, in the sixth embodiment, the length of the signal invalid period is set to different lengths according to the catalyst deterioration diagnosis interval that varies depending on the operating state of the engine 20 .
Note that even if the catalyst deterioration diagnosis interval is changed according to the operating state of the engine 20, the catalyst deterioration diagnosis interval does not necessarily differ between the two cases in which the operating state of the engine 20 differs. Diagnostic intervals may be the same. In the two cases where the operating conditions of the engine 20 are different and the catalyst deterioration diagnosis interval is the same, the length of the signal invalid period may be different or the same depending on the operating condition of the engine 20 .
　第６実施形態において、エンジン２０の運転状態に応じて信号無効期間の長さを異ならせたが、エンジン２０の運転状態によらず、信号無効期間の長さを常に同じ長さとしてもよい。 In the sixth embodiment, the length of the signal invalid period is varied according to the operating state of the engine 20, but the length of the signal invalid period may always be the same regardless of the operating state of the engine 20.
　第１～第６実施形態において、触媒劣化診断装置８０は、上流酸素濃度センサ７６の信号に基づいて、基本燃料量供給量に対する補正量を決定するための補正係数を増加／減少させることによって、燃料量Ｈを増加／減少させてもよい。このとき、補正係数は、例えば、燃焼室３０に供給される燃料量Ｈが多いときほど値が大きくなる係数である。 In the first to sixth embodiments, the catalyst deterioration diagnosis device 80 increases/decreases the correction coefficient for determining the correction amount for the basic fuel supply amount based on the signal from the upstream oxygen concentration sensor 76. The fuel amount H may be increased/decreased. At this time, the correction coefficient is, for example, a coefficient whose value increases as the amount of fuel H supplied to the combustion chamber 30 increases.
　２０：エンジン、３０：燃焼室、５３：触媒、７６：上流酸素濃度センサ、７７：下流酸素濃度センサ、８０：触媒劣化診断装置、Ｋ１，Ｋ２：突発的信号反転組、Ｍ１，Ｍ２：信号無効期間、Ｒ１，Ｒ２：反転判定期間（第１反転判定期間、第２反転判定期間）、Ｔ１ａ，Ｔ２ａ，Ｔ３ａ，Ｔ４ａ，Ｔ５ａ：信号反転タイミング（第１信号反転タイミング、第２信号反転タイミング）、Ｗ１，Ｗ２：触媒劣化診断間隔、Ｘ１ａ，Ｘ１ｂ，Ｘ２ａ，Ｘ２ｂ：突発的信号反転組の長さ 20: Engine, 30: Combustion Chamber, 53: Catalyst, 76: Upstream Oxygen Concentration Sensor, 77: Downstream Oxygen Concentration Sensor, 80: Catalyst Deterioration Diagnosis Device, K1, K2: Sudden Signal Inversion Group, M1, M2: Signal Invalidation period, R1, R2: inversion determination period (first inversion determination period, second inversion determination period), T1a, T2a, T3a, T4a, T5a: signal inversion timing (first signal inversion timing, second signal inversion timing), W1, W2: catalyst deterioration diagnosis interval, X1a, X1b, X2a, X2b: length of sudden signal inversion set

Claims (4)

  1. 　エンジンの燃焼室から排出される排ガスの流れ方向において触媒の上流に配置され、混合気の空燃比がリッチとリーンのどちらであるかに応じた信号を出力する上流酸素濃度センサの出力信号のリッチ／リーン状態の反転に基づいて、前記エンジンに供給する燃料量の増加／減少の反転が行われるように前記エンジンを運転させ、
    　前記上流酸素濃度センサの出力信号のリッチ／リーン状態が反転する第１信号反転タイミングと、前記第１信号反転タイミングの次に前記上流酸素濃度センサの出力信号のリッチ／リーン状態が反転する第２信号反転タイミングとの間隔を信号反転間隔と定義すると、
    　前記信号反転間隔が前記触媒の劣化診断に適した触媒劣化診断間隔となるように前記エンジンが運転されているときに、排ガスの流れ方向において触媒の下流に配置された下流酸素濃度センサの出力信号に応じて前記触媒の劣化診断を行う触媒劣化診断装置であって、
    　前記信号反転間隔が前記触媒劣化診断間隔となるように前記エンジンが運転されているときの前記第１信号反転タイミングと前記第２信号反転タイミングとの間の期間に突発的に発生する、前記上流酸素濃度センサの出力信号におけるリッチ／リーン状態の反転とこれに続くリッチ／リーン状態の反転との組を突発的信号反転組と定義し、
    　前記突発的信号反転組における先のリッチ／リーン状態の反転と後のリッチ／リーン状態の反転との間隔を、突発的信号反転組の長さと定義し、
    　前記信号反転間隔が前記触媒劣化診断間隔となるように前記エンジンが運転されているときの、前記第２信号反転タイミングと、その後前記上流酸素濃度センサの出力信号の前記第２信号反転タイミングでのリッチ／リーン状態の反転に基づいて前記燃料量の増加／減少を反転させることが決定されるタイミングとの間隔を第１反転判定期間と定義したときに、
    　前記信号反転間隔が前記触媒劣化診断間隔となるように前記エンジンが運転されているときの前記第１信号反転タイミングと前記第２信号反転タイミングとの間の期間に信号無効期間を設け、前記信号無効期間に前記突発的信号反転組が発生し、当該突発的信号反転組の長さが前記第１反転判定期間よりも長く、かつ、当該突発的信号反転組が前記第１信号反転タイミングと前記第２信号反転タイミングとの間の期間内に収まる場合に、当該突発的信号反転組を無視して燃料量の増加／減少を反転させないように制御することを特徴とする触媒劣化診断装置。     Rich in the output signal of an upstream oxygen concentration sensor that is arranged upstream of the catalyst in the flow direction of the exhaust gas discharged from the combustion chamber of the engine and outputs a signal according to whether the air-fuel ratio of the air-fuel mixture is rich or lean. / operating the engine such that an increase/decrease reversal of the amount of fuel supplied to the engine is performed based on the reversal of the lean condition;
    a first signal inversion timing at which the rich/lean state of the output signal of the upstream oxygen concentration sensor is inverted; and a second signal inversion timing at which the rich/lean state of the output signal of the upstream oxygen concentration sensor is inverted following the first signal inversion timing. If the interval from the signal inversion timing is defined as the signal inversion interval,
    An output signal of a downstream oxygen concentration sensor arranged downstream of the catalyst in the exhaust gas flow direction when the engine is operated such that the signal inversion interval is a catalyst deterioration diagnosis interval suitable for deterioration diagnosis of the catalyst. A catalyst deterioration diagnosis device for diagnosing deterioration of the catalyst according to
    The upstream which suddenly occurs during the period between the first signal inversion timing and the second signal inversion timing when the engine is operated such that the signal inversion interval is equal to the catalyst deterioration diagnosis interval. defining a set of rich/lean state inversions followed by rich/lean state inversions in the output signal of the oxygen concentration sensor as an abrupt signal inversion pair;
    defining an interval between an earlier rich/lean state reversal and a later rich/lean state reversal in the set of abrupt signal inversions as a set of abrupt signal inversions;
    When the engine is operated such that the signal inversion interval is equal to the catalyst deterioration diagnosis interval, the second signal inversion timing and the output signal of the upstream oxygen concentration sensor at the second signal inversion timing after that. When the first reversal determination period is defined as the interval from the timing at which it is determined to reverse the increase/decrease of the fuel amount based on the reversal of the rich/lean state,
    A signal invalid period is provided in a period between the first signal inversion timing and the second signal inversion timing when the engine is operated such that the signal inversion interval is equal to the catalyst deterioration diagnosis interval, and the signal The abrupt signal inversion group occurs during the invalid period, the length of the abrupt signal inversion group is longer than the first inversion determination period, and the abrupt signal inversion group is the first signal inversion timing and the abrupt signal inversion group. A catalyst deterioration diagnostic device that ignores the sudden signal inversion set and performs control so as not to reverse the increase/decrease of the fuel quantity when it falls within the period between the second signal inversion timing.
  2. 　前記信号反転間隔が前記触媒劣化診断間隔となるように前記エンジンが運転されているときの、前記第１信号反転タイミングと、その後前記上流酸素濃度センサの出力信号の前記第１信号反転タイミングでのリッチ／リーン状態の反転に基づいて前記燃料量の増加／減少を反転させることが決定されるタイミングとの間隔を第２反転判定期間と定義したときに、
    　前記信号無効期間の開始タイミングを、前記第１信号反転タイミングの後、前記第２反転判定期間が経過したタイミングとなるように制御する、請求項１に記載の触媒劣化診断装置。     When the engine is operated such that the signal inversion interval is equal to the catalyst deterioration diagnosis interval, the first signal inversion timing and then the output signal of the upstream oxygen concentration sensor at the first signal inversion timing. When the second reversal determination period is defined as the interval from the timing at which it is determined to reverse the increase/decrease of the fuel amount based on the reversal of the rich/lean state,
    2. The catalyst deterioration diagnostic device according to claim 1, wherein the start timing of the signal invalid period is controlled to be the timing when the second inversion determination period has passed after the first signal inversion timing.
  3. 　前記信号反転間隔が前記触媒劣化診断間隔となるように前記エンジンが運転されているとき以外には、前記信号無効期間を設けないように制御する、請求項１または２に記載の触媒劣化診断装置。 3. The catalyst deterioration diagnosis device according to claim 1, wherein control is performed so that the signal invalid period is not provided except when the engine is operated such that the signal inversion interval is equal to the catalyst deterioration diagnosis interval. .
  4. 　前記信号無効期間を、前記エンジンの運転状態に応じて異なった長さに設定するように制御する、請求項１～３のいずれかに記載の触媒劣化診断装置。

          4. The catalyst deterioration diagnostic device according to claim 1, wherein said signal invalid period is controlled to be set to different lengths depending on the operating state of said engine.
PCT/JP2021/035337 2021-09-27 2021-09-27 Catalyst deterioration diagnosis device WO2023047571A1 (en)

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DE112021002324.1T DE112021002324T5 (en) 2021-09-27 2021-09-27 DEVICE FOR DIAGNOSIS OF DETERIORATION OF A CATALYST
PCT/JP2021/035337 WO2023047571A1 (en) 2021-09-27 2021-09-27 Catalyst deterioration diagnosis device
FR2209606A FR3127528A1 (en) 2021-09-27 2022-09-22 Catalyst damage diagnostic device

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6432043A (en) * 1987-07-28 1989-02-02 Mazda Motor Air-fuel ratio controller for engine
JPH06129294A (en) * 1992-10-20 1994-05-10 Honda Motor Co Ltd Air-fuel ratio control device of internal combustion engine
JPH11287145A (en) * 1998-04-02 1999-10-19 Toyota Motor Corp Air-fuel ratio controller for multiple cylinder internal combustion engine

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6432043A (en) * 1987-07-28 1989-02-02 Mazda Motor Air-fuel ratio controller for engine
JPH06129294A (en) * 1992-10-20 1994-05-10 Honda Motor Co Ltd Air-fuel ratio control device of internal combustion engine
JPH11287145A (en) * 1998-04-02 1999-10-19 Toyota Motor Corp Air-fuel ratio controller for multiple cylinder internal combustion engine

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