WO2013153610A1 - Control device for internal combustion engine - Google Patents

Control device for internal combustion engine Download PDF

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Publication number
WO2013153610A1
WO2013153610A1 PCT/JP2012/059724 JP2012059724W WO2013153610A1 WO 2013153610 A1 WO2013153610 A1 WO 2013153610A1 JP 2012059724 W JP2012059724 W JP 2012059724W WO 2013153610 A1 WO2013153610 A1 WO 2013153610A1
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WIPO (PCT)
Prior art keywords
catalyst
amount
air
fuel ratio
hydrogen
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PCT/JP2012/059724
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French (fr)
Japanese (ja)
Inventor
岡崎　俊太郎
中川　徳久
雄士 山口
藤原　孝彦
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トヨタ自動車株式会社
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Priority to PCT/JP2012/059724 priority Critical patent/WO2013153610A1/en
Publication of WO2013153610A1 publication Critical patent/WO2013153610A1/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
    • 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
    • F01N3/18—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 characterised by methods of operation; Control
    • F01N3/20—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 characterised by methods of operation; Control specially adapted for catalytic conversion ; Methods of operation or control of catalytic converters
    • 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
    • F02D41/008—Controlling each cylinder individually
    • 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
    • F01N3/0828—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents characterised by the absorbed or adsorbed substances
    • F01N3/085—Sulfur or sulfur oxides
    • 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
    • F01N3/0871—Regulation of absorbents or adsorbents, e.g. purging
    • F01N3/0885—Regeneration of deteriorated absorbents or adsorbents, e.g. desulfurization of NOx traps
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D13/00—Controlling the engine output power by varying inlet or exhaust valve operating characteristics, e.g. timing
    • F02D13/02—Controlling the engine output power by varying inlet or exhaust valve operating characteristics, e.g. timing during engine operation
    • F02D13/0223—Variable control of the intake valves only
    • F02D13/0234—Variable control of the intake valves only changing the valve timing only
    • F02D13/0238—Variable control of the intake valves only changing the valve timing only by shifting the phase, i.e. the opening periods of the valves are constant
    • 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
    • F02D41/021—Introducing corrections for particular conditions exterior to the engine
    • F02D41/0235—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus
    • F02D41/027—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus to purge or regenerate the exhaust gas treating apparatus
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
    • F02M26/13—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories
    • F02M26/14—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories in relation to the exhaust system
    • F02M26/15—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories in relation to the exhaust system in relation to engine exhaust purifying apparatus
    • 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
    • F02D41/0002—Controlling intake air
    • F02D2041/001—Controlling intake air for engines with variable valve actuation
    • 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
    • F02D41/30—Controlling fuel injection
    • 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
    • Y02T10/12—Improving ICE efficiencies

Definitions

  • the present invention relates to a technical field of a control device for an internal combustion engine suitable for recovering an exhaust purification catalyst installed in an exhaust path from sulfur poisoning.
  • the exhaust purification catalyst installed in the exhaust path adsorbs sulfur contained as impurities in the fuel to the noble metal added to the catalyst and poisons the sulfur.
  • sulfur poisoning the activity of the catalyst is remarkably lost, and the original exhaust purification action of the catalyst cannot be obtained. Therefore, various sulfur poisoning recovery controls have been proposed for desorbing sulfur from the catalyst. Yes.
  • sulfur is oxidized inside the cylinder or in the exhaust path and is adsorbed to the catalyst as SOx (sulfur oxide), and the desorption of sulfur simply means reduction of sulfur.
  • Patent Document 1 discloses sulfur poisoning recovery control in a lean NOx catalyst.
  • the exhaust gas purification apparatus for an internal combustion engine disclosed in Patent Document 1 includes an H 2 (hydrogen) sensor upstream of the lean NOx catalyst, and rich combustion in the cylinder is controlled based on the output value of the H 2 sensor. It is the composition which becomes. That is, it is configured that the H 2 concentration of the catalyst inflow gas is F / B controlled to a rich combustion control amount, and an appropriate amount of hydrogen can be supplied at the time of sulfur poisoning recovery.
  • H 2 hydrogen
  • Patent Document 2 discloses a technique for raising the temperature of the catalyst by controlling some cylinders to be rich in the air-fuel ratio and the remaining cylinders to be air-fuel ratio lean.
  • Patent Document 3 discloses a configuration in which H 2 is supplied by an H 2 supply means mounted upstream of the catalyst when the amount of sulfur accumulated in the NOx catalyst exceeds a predetermined value.
  • Patent Document 4 a CO 2 adsorbent, an H 2 generation catalyst, and a NOx catalyst are arranged in an exhaust system of a lean combustion engine, and CO is supplied to the H 2 generation catalyst, which is generated by an aquatic gas shift reaction.
  • a configuration in which H 2 is sent as a reducing agent to the NOx catalyst is disclosed.
  • Patent Document 5 discloses a lean NOx catalyst system, and in an internal combustion engine capable of controlling in-cylinder combustion, when NOx catalyst is regenerated, post-injection timing is performed at a timing when the dehydrogenation reaction and cracking reaction repel each other.
  • the structure to perform is disclosed.
  • Patent Document 1 does not mention anything about this point.
  • combustion on the rich side of the air-fuel ratio is a disadvantageous control from the viewpoint of exhaust emission, apart from the reduction of sulfur and NOx, and is also economically disadvantageous in that it leads to a deterioration in fuel consumption. Control. Therefore, it is not reasonable to perform rich combustion in the dark cloud on the safe side (in this case, that is, on the side where the amount of hydrogen generated increases) for the purpose of reducing only sulfur.
  • the present invention has been made in view of the above-described circumstances, and provides an internal combustion engine control device capable of recovering a catalyst from sulfur poisoning while suppressing an increase in cost and deterioration of exhaust emission and fuel consumption. This is the issue.
  • an internal combustion engine control apparatus controls an internal combustion engine including a plurality of cylinders and an exhaust purification catalyst installed in an exhaust path connected to the plurality of cylinders.
  • a control unit for an internal combustion engine that determines whether or not to perform sulfur poisoning recovery of the catalyst; and exhaust gas that flows into the catalyst when it is determined to perform sulfur poisoning recovery.
  • Poisoning recovery control means for controlling the air-fuel ratio of the plurality of cylinders, wherein the poisoning recovery control means controls the degree of imbalance of the air-fuel ratio among the plurality of cylinders (first item) ).
  • the internal combustion engine according to the present invention is a concept encompassing an engine that can convert thermal energy generated when an air-fuel mixture containing fuel burns into kinetic energy and take it out.
  • the number of cylinders, the cylinder arrangement, the fuel type, the fuel injection mode, the intake / exhaust system configuration, the valve train configuration, the combustion system, the presence / absence of the supercharger, and the excess is not limited in any way.
  • the exhaust purification catalyst according to the present invention is a concept encompassing various types of catalysts that can be provided in the exhaust path of an internal combustion engine.
  • a three-way catalyst for example, a lean NOx catalyst (also referred to as a NOx storage reduction catalyst).
  • Practical forms such as oxidation catalyst.
  • the catalyst is poisoned by sulfur contained as an impurity in the fuel according to the actual operation period of the internal combustion engine. Since sulfur poisoning of the catalyst reduces the catalytic activity, it is necessary to desorb sulfur from the catalyst at the appropriate timing (that is, to recover the catalyst from sulfur poisoning). In the control apparatus for an internal combustion engine according to the present invention, it is determined by the determining means whether or not to perform sulfur poisoning recovery. “Sulfur poisoning recovery” is a concept encompassing control, processing and measures for recovering the catalyst from the sulfur poisoning state.
  • the criteria for determining whether or not the determination means implements sulfur poisoning recovery is ambiguous. For example, in practice, it is effective to perform sulfur poisoning recovery at a timing at which the degree of sulfur poisoning can be considered to have exceeded a predetermined level, but the timing at which sulfur poisoning recovery measures are taken is not limited to this. . That is, the determination means may determine that the sulfur poisoning recovery is performed when the elapsed time after the internal combustion engine has been operated exceeds a predetermined value, or more fluidly, the internal combustion engine is stationary. It may be determined that the sulfur poisoning recovery is performed at an appropriate timing in the operating state. That is, the recovery from sulfur poisoning is effective regardless of the level of sulfur poisoning of the catalyst.
  • the control apparatus for an internal combustion engine controls the air-fuel ratio of the exhaust gas flowing into the catalyst (hereinafter referred to as “catalyst inflow gas” as appropriate) by the poisoning recovery control means. More specifically, the poisoning recovery control means is configured to control the degree of air-fuel ratio imbalance among a plurality of cylinders.
  • the imbalance as the degree of imbalance Depending on the degree, the amount of hydrogen produced in the cylinder can be controlled.
  • the average air fuel ratio of all the cylinders in one cycle is always desired value (for example, theoretical air fuel ratio equivalent value). ) Can be maintained. That is, although it is necessary to individually control the air-fuel ratio for each cylinder, it is possible to supply hydrogen to the catalyst without apparently changing the air-fuel ratio of the catalyst inflow gas from when sulfur poisoning recovery is not performed. . Therefore, drivability and power performance deterioration due to torque fluctuation, and emission and fuel consumption deterioration can be suitably suppressed.
  • the control device for an internal combustion engine according to the present invention has a great practical advantage in that an increase in cost can be avoided.
  • air-fuel ratio imbalance in the present invention is a quantitative index that means the degree of air-fuel ratio imbalance among a plurality of cylinders, and its practical aspect is within the scope of the concept. Ambiguous. Further, the degree of imbalance of the air-fuel ratio may be a value determined for the internal combustion engine or a value determined for each cylinder according to a practical definition.
  • the “degree of air-fuel ratio imbalance” may include, for example, those defined in (1) to (4) below.
  • the “corresponding value” below is a concept that includes a control amount, a physical amount, or an index value that can have a unique relationship with the target value.
  • a value corresponding to the ratio of the air-fuel ratio of each cylinder to the average value of the air-fuel ratio of all cylinders (2) A value corresponding to the ratio of the air-fuel ratio of a specific cylinder to the air-fuel ratio of the remaining cylinders (3) Target A value corresponding to the ratio of the deviation between the target air-fuel ratio and the air-fuel ratio of each cylinder with respect to the air-fuel ratio (4) A value corresponding to the ratio of the air-fuel ratio of each cylinder with respect to the target air-fuel ratio It is desirable that the air-fuel ratio rich side cylinder and the air-fuel ratio lean side cylinder are not fixed.
  • the deviation between the cylinders in the average air-fuel ratio of a cylinder should be small within one sulfur poisoning recovery cycle or between a plurality of sulfur poisoning recovery cycles. This is because if the cylinder on the air-fuel ratio rich side is always fixed, the in-cylinder state of each cylinder may vary every time the sulfur poisoning recovery is repeated.
  • control apparatus further includes an accumulation amount estimation unit that estimates an accumulation amount of sulfur in the catalyst, and the determination unit is configured to determine the sulfur based on the estimated accumulation amount. It is determined whether or not poisoning recovery is carried out (2nd term).
  • the accumulated amount estimating means estimates the accumulated amount of sulfur in the catalyst, and the estimated accumulated amount is used to determine whether or not the sulfur poisoning recovery is performed by the determining means. Therefore, the catalyst can be accurately recovered from the sulfur poisoning at a stage where the sulfur poisoning to some extent is efficient.
  • the “accumulation amount” estimated by the accumulation amount estimation means includes physical accumulation amount, adhesion amount, adsorption amount accompanied by chemical adsorption process, etc., and sulfur poisoning process (depending on the catalyst).
  • the expressions may vary.
  • the accumulated amount is an experimental value in advance of an internal combustion engine operating parameter that may include at least part of the engine speed, intake pressure, accelerator opening, intake air amount, throttle opening, load factor, and fuel injection amount. It may be estimated based on the correlation between the operating parameter and the amount of sulfur production, which is established empirically or theoretically.
  • the amount of sulfur or sulfur oxide (SOx) discharged per unit time in the exhaust path of the internal combustion engine may be integrated, and the accumulated amount may be estimated from this integrated value.
  • the relationship between the integrated value and the actual accumulated amount is clear (that is, not all sulfur or sulfur oxide discharged from the cylinder is deposited on the catalyst), the relationship is further referred to. May be.
  • control device further includes in-catalyst production amount estimation means for estimating a production amount of hydrogen in the catalyst, and the determination means generates hydrogen in the estimated catalyst. It is determined whether or not the sulfur poisoning recovery is performed based on the amount (Section 3).
  • the control device for an internal combustion engine has a technical idea of recovering from sulfur poisoning by supplying hydrogen generated in the cylinder to the catalyst. However, depending on the configuration and type of the catalyst, It is also produced in the catalyst. Since hydrogen produced by the catalyst and hydrogen produced inside the cylinder are not distinguished from the viewpoint of recovering sulfur from poisoning, in determining whether to perform sulfur poisoning recovery, It is desirable to consider the amount of hydrogen produced. According to this aspect, the amount of hydrogen produced in the catalyst is estimated by the in-catalyst generation amount estimation means, and this estimation result is taken into account when the determination means determines whether or not to perform sulfur poisoning recovery.
  • the hydrogen generated in the cylinder is reduced. It is possible to appropriately determine that the used sulfur poisoning recovery is unnecessary.
  • hydrogen generated in the catalyst cannot be fully used for recovery of sulfur poisoning, so that sulfur poisoning recovery using hydrogen generated in the cylinder is more effective. A determination that it is necessary can be made as appropriate. Therefore, the execution timing, the execution frequency, and the implementation scale of the sulfur poisoning recovery by the sulfur poisoning recovery control means can be more optimally maintained according to the actual situation.
  • the amount of hydrogen produced in the catalyst can be determined in advance, for example, experimentally, empirically, or theoretically, using various operating conditions of the internal combustion engine as parameters. It can be made available as data on the map. Alternatively, the hydrogen generation process in the catalyst is converted into an arithmetic algorithm, the instantaneous hydrogen generation amount is obtained based on the operating conditions of the internal combustion engine at that time, and the instantaneous generation amount is integrated for a predetermined period, thereby The amount of hydrogen generation may be estimated.
  • the in-catalyst production amount estimation means may estimate the production amount of hydrogen by the water gas shift reaction and the steam reforming reaction as the production amount of hydrogen in the catalyst.
  • the amount of hydrogen produced in the catalyst varies depending on the type of catalyst, but basically varies depending on the catalyst bed temperature.
  • the water temperature shift reaction CO + H 2 O ⁇ H 2 + CO 2
  • the steam reforming reaction on the high temperature side with a temperature range of about 600 to 700 ° C. as a boundary.
  • hydrogen is generated by (HC + H 2 O ⁇ H 2 + CO). Therefore, according to this aspect, the amount of hydrogen produced in the catalyst is required and can be estimated with sufficient accuracy.
  • an arithmetic expression, a control map, and the like are prepared in advance for associating the hydrogen generation amount or hydrogen concentration by the reaction with the catalyst bed temperature. Also good.
  • an accumulation amount estimation means for estimating an accumulation amount of sulfur in the catalyst and an in-catalyst production amount estimation means for estimating an amount of hydrogen generation in the catalyst.
  • the determination means determines whether or not to perform the sulfur poisoning recovery based on the estimated sulfur accumulation amount in the catalyst and the estimated hydrogen generation amount in the catalyst (Section 5). ).
  • the sulfur accumulation amount estimated by the accumulation amount estimation means equivalent to that described above, and the hydrogen production amount estimated by the in-catalyst production amount estimation means equivalent to those described above Based on the above, it is determined whether or not to perform sulfur poisoning recovery. For example, when the reaction amount of sulfur is calculated from the estimated amount of hydrogen generated in the catalyst, and the difference value obtained by subtracting the calculated reaction amount from the estimated amount of accumulated sulfur is a predetermined value or more, etc. A decision is made to implement sulfur poisoning recovery.
  • an accumulation amount estimation means for estimating the amount of sulfur accumulation in the catalyst an in-catalyst production amount estimation means for estimating the amount of hydrogen production in the catalyst, Based on the estimated amount of accumulated sulfur and the estimated amount of hydrogen generated in the catalyst, the required amount estimating means for estimating the required amount of hydrogen in the cylinder, and in the cylinder by controlling the degree of imbalance
  • An in-cylinder generation amount estimation means for estimating the amount of hydrogen generation, and the poisoning recovery control means is based on the estimated hydrogen generation amount in the cylinder so as to obtain the estimated required amount.
  • the degree of imbalance is controlled (sixth term).
  • the control of the air-fuel ratio imbalance degree by the poisoning recovery control means is the combustion state of the individual cylinders. Realized by deviating from the ideal combustion state. Therefore, it is desirable that the amount of hydrogen generated inside the cylinder for recovering the catalyst from sulfur poisoning is an amount necessary and sufficient to recover the sulfur poisoning of the catalyst.
  • the request amount estimation unit determines the hydrogen content in the cylinder. Estimate the required amount.
  • the required amount is a concept including a concentration defined as weight or volume per unit time or unit volume in addition to typical quantitative indicators such as weight and volume.
  • the required amount estimating means subtracts the amount of hydrogen generated in the catalyst estimated by the in-catalyst generation amount estimating means from the accumulated amount estimated by the accumulated amount estimating means, and determines the degree of imbalance by the poisoning recovery control means.
  • the required amount of hydrogen to be generated by control may be estimated.
  • the required amount estimation means for example, corrects the accumulation amount estimated by the accumulation amount estimation means to the subtraction side according to the hydrogen production amount in the catalyst estimated by the in-catalyst production amount estimation means, etc.
  • the required amount may be estimated.
  • the in-cylinder generation amount estimation means estimates the amount of hydrogen generated in the cylinder by controlling the degree of imbalance.
  • the amount of hydrogen generated in the cylinder is a concept including a concentration defined as a unit time or a weight or volume per unit volume, in addition to a typical quantitative index such as weight or volume. .
  • the control device for an internal combustion engine according to the present invention employs a configuration in which the amount of hydrogen produced in the cylinder is controlled by controlling the degree of imbalance, so that the degree of imbalance and the amount of hydrogen produced in the cylinder or the amount of hydrogen produced
  • the relationship with the hydrogen concentration according to is given experimentally, empirically or theoretically in advance.
  • the estimated amount of hydrogen generated in the cylinder is determined so that the estimated recovery amount is obtained by the poisoning recovery control means.
  • the degree of imbalance is controlled based on this.
  • the practical control mode of the imbalance degree may be various.
  • the sulfur poisoning recovery time may be determined from the estimated hydrogen generation amount in the cylinder.
  • the target value of the imbalance degree is set so that the catalyst recovers from sulfur poisoning within the period. May be determined.
  • the amount of hydrogen generated in the cylinder by the poisoning recovery control means can always be optimized according to the degree of sulfur poisoning of the catalyst, and the increase in cost and the deterioration of emission and fuel consumption are suppressed.
  • the catalyst can be recovered from sulfur poisoning. For example, if the required amount of hydrogen in the cylinder is estimated according to only the amount of sulfur accumulated in the catalyst, the amount of hydrogen supplied to the catalyst becomes excessive by the amount of hydrogen produced in the catalyst. In other words, the amount of hydrogen supplied to the catalyst is larger than necessary and sufficient, and the time for the combustion state of the internal combustion engine to deviate from the ideal combustion state becomes unnecessarily long, and exhaust emissions and fuel consumption deteriorate. Turn into. In this aspect, such a situation is avoided.
  • the in-catalyst generation amount estimation means may estimate the amount of hydrogen generation in the catalyst based on the temperature of the catalyst that changes due to the control of the imbalance degree (Seventh Item). .
  • the catalyst bed temperature is related to the amount of hydrogen produced in the catalyst, and the relationship can be determined experimentally, empirically or theoretically in advance.
  • the in-catalyst generation amount estimation means estimates the hydrogen generation amount in the catalyst in consideration of such an action of increasing the catalyst bed temperature.
  • the configuration for estimating the hydrogen production amount in the catalyst from the result of the imbalance is a kind of circulation reference. At first glance it lacks logical consistency.
  • the imbalance control by the poisoning recovery control means is preferably continued until the sulfur accumulation amount is sufficiently reduced with reference to the sulfur accumulation amount of the catalyst that changes in real time. In calculating the remaining amount, it is practically possible to reflect the influence of the catalyst bed temperature changed by controlling the imbalance degree.
  • a target value of the catalyst bed temperature suitable for sulfur poisoning recovery is determined, and the degree of imbalance is controlled so that the catalyst bed temperature can be maintained at the target value.
  • the sulfur poisoning recovery may be performed for an optimal time considering the amount of hydrogen produced in
  • the target value of the imbalance degree may be determined in consideration of a change in the amount of hydrogen generated in the catalyst due to an increase in the catalyst bed temperature, and the poisoning recovery control means may control the imbalance degree.
  • the internal combustion engine includes first detection means for detecting an air-fuel ratio equivalent value of exhaust flowing into the catalyst, and an air-fuel ratio of exhaust discharged from the catalyst. And a second detecting means for detecting an equivalent value, wherein the control device for the internal combustion engine includes an air-fuel ratio equivalent value of the exhaust gas flowing into the detected catalyst and an empty air exhausted from the detected catalyst.
  • Air-fuel ratio control means for converging the air-fuel ratio inside the catalyst to the target air-fuel ratio based on the fuel-equivalent value is further provided (Section 8).
  • the first detection means capable of detecting the air-fuel ratio equivalent value of the catalyst inflow gas and the air-fuel ratio equivalent of the exhaust gas discharged from the catalyst (hereinafter referred to as “catalyst exhaust gas” as appropriate).
  • Second detection means capable of detecting a value.
  • the “air-fuel ratio equivalent value” may be a value whose behavior has a unique relationship with the air-fuel ratio, such as an oxygen concentration in addition to the air-fuel ratio itself. These may be detected as a voltage value that can be converted into an air-fuel ratio through a predetermined conversion process using, for example, an arithmetic expression or a map.
  • the air-fuel ratio of the catalyst inflow gas and the air-fuel ratio of the catalyst exhaust gas preferably mean time average values of the air-fuel ratio of these gases.
  • the air-fuel ratio control means converges the air-fuel ratio inside the catalyst to the target air-fuel ratio based on the air-fuel ratio equivalent values of the catalyst inflow gas and the catalyst exhaust gas.
  • air-fuel ratio F / B control such control of the air-fuel ratio control means is appropriately expressed as “air-fuel ratio F / B control”.
  • the fuel injection amount of each cylinder is appropriately corrected from the reference fuel injection amount so that the air-fuel ratio inside the catalyst becomes the target air-fuel ratio, but its practical aspect is ambiguous. Is.
  • the air-fuel ratio F / B may be constructed from sub F / B control using the second detection means and main F / B control using the first detection means. More specifically, in the sub F / B control, the air-fuel ratio of the catalyst exhaust gas is set to the target air according to the deviation between the air-fuel ratio detected directly or indirectly by the second detecting means and the target air-fuel ratio.
  • the sub-F / B control amount for converging to the fuel ratio is calculated, and the air-fuel ratio or its target air-fuel ratio detected directly or indirectly by the first detection means based on the sub-F / B control amount It may be constructed as a control for correcting.
  • the catalyst inflow is determined according to the deviation between the corrected air-fuel ratio and the target air-fuel ratio, or according to the deviation between the detected air-fuel ratio and the corrected target air-fuel ratio.
  • the main F / B control amount (for example, a correction coefficient to be multiplied by the reference injection amount) for converging the gas air-fuel ratio to the target air-fuel ratio is determined, and the control may be constructed to correct the reference injection amount.
  • the air-fuel ratio F / B control in the present application may be so-called PI control in which the F / B control amount includes a proportional term (P term) and an integral term (I term), or the F / B control amount, for example. May be so-called PID control constructed by adding a differential term (D term) to the proportional term and the integral term. Further, the air-fuel ratio F / B control may be performed uniformly for all cylinders or may be performed individually for each cylinder.
  • the air-fuel ratio inside the catalyst can be maintained at the target air-fuel ratio, so the degree of imbalance of the air-fuel ratio between the cylinders is changed in order to recover the catalyst from sulfur poisoning. In doing so, the influence on the air-fuel ratio of the entire engine can be reduced. Accordingly, it is possible to suitably suppress the deterioration of exhaust emission and fuel consumption.
  • the poisoning recovery control means includes a variable valve operating device capable of changing an opening / closing timing of at least one of a fuel injection device, an intake valve, and an exhaust valve, and Control at least one of the EGR devices (Section 9).
  • the air-fuel ratio imbalance occurs when the balance between the amount of air sucked into the cylinder and the amount of fuel supplied into the cylinder differs between the cylinders. Therefore, one of the most appropriate control targets for controlling the degree of air-fuel ratio imbalance is a fuel injection device capable of changing the fuel injection amount for each cylinder.
  • the intake air is different for each cylinder.
  • the amount can be changed. Therefore, hydrogen can be generated in the cylinder.
  • the intake throttle valve is independent for each cylinder, the intake air amount can be made different for each cylinder.
  • EGR exhaust Gas Recirculation
  • the ratio of fresh air to the gas sucked into the cylinder and the homogeneity of the formed air-fuel mixture can be changed.
  • the configuration is such that EGR can be introduced independently for each cylinder (for example, a configuration in which each cylinder has an EGR pipe and an EGR valve, respectively), the intake air amount can be made different for each cylinder. And an air-fuel ratio imbalance can be realized.
  • the poisoning recovery control means may further control the ignition device in addition to the device capable of changing the air-fuel ratio imbalance.
  • the ignition timing When the ignition timing is changed to the retarded angle side, the progress of the combustion reaction in the cylinder generally shifts to the retarded angle side. For this reason, it is possible to continue the combustion reaction when the exhaust valve is opened, and it is possible to increase the temperature of the exhaust path and the catalyst communicating therewith.
  • the catalyst bed temperature affects the amount of hydrogen produced in the catalyst and the desorption of sulfur in the catalyst. Therefore, it is possible to independently control the amount of hydrogen generated in the cylinder by the imbalance degree and the catalyst bed temperature through the control of the ignition timing. In this case, the imbalance degree can be controlled without considering the influence on the catalyst bed temperature, and a higher degree of freedom can be given by the control range of the imbalance degree.
  • the internal combustion engine has an internal combustion engine that uses gasoline as a fuel, a compression auto-ignition internal combustion engine that uses light oil as a fuel, or an air-fuel ratio due to stratified combustion.
  • a combustion lean combustion internal combustion engine maintained at a lean air-fuel ratio (Section 10).
  • the configuration of the catalyst or the catalyst system also changes. However, for example, whether it is a three-way catalyst or a lean NOx catalyst, the problem of sulfur poisoning can also occur.
  • the control device for an internal combustion engine according to the present invention can be applied regardless of the configuration of the internal combustion engine.
  • Compressed self-ignition internal combustion engines are mainly concerned with whether or not fresh air is sufficient for the amount of fuel, and the combustion state is controlled not by air-fuel ratio control but by injection amount control.
  • the combustion state is controlled not by air-fuel ratio control but by injection amount control.
  • 1 is a schematic configuration diagram conceptually showing a configuration of an engine system according to an embodiment of the present invention.
  • 2 is a flowchart of sulfur poisoning recovery control executed by an ECU in the engine system of FIG. 1. It is a conceptual diagram of the 1st hydrogen concentration map referred in the sulfur poisoning recovery control of FIG. It is a conceptual diagram of the 2nd hydrogen concentration map referred in the sulfur poisoning recovery control of FIG. It is a flowchart of the sulfur poisoning recovery control which concerns on 2nd Embodiment of this invention.
  • FIG. 1 is a schematic configuration diagram conceptually showing the configuration of the engine system 10.
  • an engine system 10 is mounted on a vehicle (not shown) and includes an ECU 100 and an engine 200.
  • the ECU 100 is an electronic control unit that includes a CPU, a ROM, a RAM, and the like and is configured to be able to control the operation of the engine system 10, and is an example of the “control device for an internal combustion engine” according to the present invention.
  • the ECU 100 is configured to be able to execute sulfur poisoning recovery control, which will be described later, according to a control program stored in the ROM.
  • the ECU 100 includes the “determination unit”, “accumulated amount estimation unit”, “in-catalyst generation amount estimation unit”, “in-cylinder generation amount estimation unit”, “request amount estimation unit”, “poisoning recovery” according to the present invention. It is an integrated electronic control unit that can function as an example of each of “control means” and “air-fuel ratio control means”, but the physical, mechanical, and electrical configurations of these means according to the present invention are limited to this. Instead, these means may be configured as various computer systems such as a plurality of ECUs, various processing units, various controllers, or a microcomputer device.
  • Engine 200 is a multi-cylinder gasoline engine that is an example of an “internal combustion engine” according to the present invention.
  • the engine 200 includes a plurality of cylinders 201 accommodated in a cylinder block CB.
  • the cylinders 201 are arranged in the depth direction of the drawing, and only one cylinder 201 is shown in FIG. 1.
  • the combustion chamber formed in the cylinder 201 is provided with a piston 202 that reciprocates in the vertical direction in the figure in accordance with the explosive force accompanying the combustion of the air-fuel mixture.
  • the reciprocating motion of the piston 202 is converted into the rotational motion of the crankshaft 204 via the connecting rod 203 and is used as power for the vehicle on which the engine 200 is mounted.
  • crank position sensor 205 capable of detecting the rotational position (ie, crank angle) of the crankshaft 204 is installed.
  • the crank position sensor 205 is electrically connected to the ECU 100, and the detected crank angle is referred to the ECU 100 at a constant or indefinite period.
  • the crank position sensor 205 is used for calculation of the engine speed NE or other control. It becomes the composition which is done.
  • air sucked from the outside is purified by a cleaner (not shown) and then guided to a common intake pipe 206 for each cylinder.
  • the intake pipe 206 is provided with a throttle valve 207 that can adjust the amount of intake air that is the amount of intake air.
  • the throttle valve 207 is configured as a kind of electronically controlled throttle valve whose driving state is controlled by a throttle valve motor (not shown) electrically connected to the ECU 100.
  • the ECU 100 basically drives and controls the throttle valve motor so as to obtain a throttle opening corresponding to an accelerator opening Ta detected by an unillustrated accelerator position sensor. However, the ECU 100 can also adjust the throttle opening without intervention of the driver's intention through the operation control of the throttle valve motor.
  • the intake air appropriately adjusted by the throttle valve 207 is sucked into the cylinder through the intake port 208 corresponding to each cylinder 201 when the intake valve 209 is opened.
  • the intake valve 209 is configured such that its opening / closing timing is defined according to the cam profile of a cam 210 having a substantially elliptical shape in cross section as shown in the figure.
  • the cam 210 is fixed to an intake camshaft (reference number omitted) connected to the crankshaft 204 via power transmission means such as a cam sprocket or a timing chain. Therefore, the opening / closing phase of the intake valve 209 is uniquely related to the rotation phase of the crankshaft 204 (ie, the crank angle) in one fixed state.
  • the fixed state between the intake cam 210 and the intake camshaft varies depending on the hydraulic pressure of the control oil supplied by the hydraulic drive device 211.
  • the intake cam 210 is connected to the intake cam shaft via a wing-like member called a vane, and the rotational phase between the vane and the intake cam shaft is applied to the hydraulic chamber of the hydraulic drive device 211.
  • the configuration changes according to the hydraulic pressure applied. Therefore, the rotational phase between the intake cam 210 fixed to the vane and the intake camshaft also changes according to the hydraulic pressure.
  • the hydraulic drive device 211 is in a state of being electrically connected to the ECU 100, and the ECU 100 can change the opening / closing timing of the intake valve 209 independently for each cylinder through the control of the hydraulic drive device 211. That is, the hydraulic drive device 211 is an example of a configuration that can be adopted by the “variable valve operating device” according to the present invention.
  • variable valve apparatus which concerns on this invention can take is not limited to the thing of this embodiment.
  • the intake valve 209 may be a so-called electromagnetically driven valve (cam-by-wire) that is electromagnetically driven by a solenoid actuator or the like.
  • the intake air guided to the intake port 208 is mixed with the fuel (gasoline) injected from the intake port injector 212 in which a part of the injection valve is exposed at the intake port 208 to become the above-described mixture.
  • Gasoline as fuel is stored in a fuel tank (not shown), and is supplied to the intake port injector 212 via a delivery pipe (not shown) by the action of a low-pressure feed pump (not shown).
  • a drive device (not shown) that drives the injection valve is electrically connected to the ECU 100, and the intake port injector 212 controls the valve opening period of the injection valve via the drive device. By doing so, an amount of fuel spray corresponding to this valve opening period can be supplied to the intake port 208.
  • the intake port injector 212 is an example embodiment that corresponds to the “fuel injection device” according to the present invention.
  • a part of a spark plug (not shown) of an ignition device 213 that is a spark ignition device is exposed.
  • the air-fuel mixture compressed in the compression stroke of the engine 200 is ignited and burned by the ignition operation of the spark plug.
  • the ignition device 213 is electrically connected to the ECU 100, and the ignition timing of the ignition device 213 is controlled by the ECU 100.
  • the air-fuel mixture that has undergone a combustion reaction in the combustion chamber is opened and closed by an exhaust valve 215 that is driven to open and close by the cam profile of the exhaust cam 214 that is indirectly connected to the crankshaft 204 in the exhaust stroke following the combustion stroke.
  • the exhaust port 216 is discharged.
  • the exhaust port 216 is connected to an exhaust manifold (not shown in FIG. 1 because of its cross-sectional view) on the downstream side (side away from the cylinder 201).
  • the exhaust manifold is a device that guides the exhaust discharged from the exhaust port 216 to the exhaust pipe 219 after collecting all the cylinders, and is connected to the exhaust pipe 219.
  • EGR pipe 217 One end of an EGR pipe 217 is connected to the exhaust manifold connected to the exhaust port 216.
  • the other end of the EGR pipe 217 is connected to an intake manifold (reference numeral omitted) located on the upstream side of the intake port 208, and a part of the exhaust can be returned to the intake system as EGR gas.
  • the EGR amount that is the supply amount of EGR gas is controlled by an EGR valve 218 installed in the EGR pipe 217.
  • the EGR valve 218 is an electromagnetically driven valve that controls the opening and closing of the valve by the electromagnetic force of the solenoid, and the valve opening degree is controlled by the control of the ECU 100 electrically connected to the drive device that controls the excitation state of the solenoid. It becomes the composition which is done.
  • the EGR pipe 217 is connected to the exhaust manifold connected to the exhaust port 216.
  • the EGR pipe 217 may be connected to the exhaust pipe 219 connected to the exhaust manifold.
  • the EGR pipe 217 is connected to the exhaust system on the upstream side (cylinder side) from the three-way catalyst 220 described later, and the EGR pipe 217 and the EGR valve 218 provide the “EGR” according to the present invention.
  • An HPL (High Pressure Loop) EGR device which is an example of the “device”, is configured.
  • the configuration of the EGR device is not limited to this.
  • the EGR device may be an LPL (Low Pressure-Loop) EGR device in which the EGR pipe 217 is connected to the downstream side of a three-way catalyst 220 described later in the exhaust pipe 219 and takes out exhaust gas after passing through the three-way catalyst.
  • the exhaust pipe 219 is connected to the exhaust port 216 of each cylinder.
  • the exhaust pipe 214 is an example of an “exhaust path” according to the present invention.
  • the exhaust pipe 219 is provided with a three-way catalyst 220 as an example of the “exhaust purification catalyst” according to the present invention.
  • the three-way catalyst 215 is a known catalyst device in which a noble metal such as platinum is supported on a catalyst carrier.
  • the three-way catalyst 215 emits exhaust gas by causing the oxidative combustion reaction of HC and CO and the reduction reaction of nitrogen oxide NOx to proceed substantially simultaneously. It can be purified. Note that when the three-way catalyst 220 is installed in the exhaust pipe 219 connected to the exhaust manifold, the exhaust gas flowing into the three-way catalyst 220 in this embodiment is the exhaust after being aggregated for all the cylinders of the engine 200. is there.
  • the input side air-fuel ratio A / Fin that is the air-fuel ratio of the catalyst inflow gas (exhaust after being aggregated for all cylinders) flowing into the three-way catalyst 220 can be detected.
  • An air-fuel ratio sensor 221 is installed.
  • the air-fuel ratio sensor 221 is, for example, a limiting current type wide-area air-fuel ratio sensor provided with a diffusion resistance layer, and is an example of the “first detection means” according to the present invention.
  • the air-fuel ratio sensor 221 outputs the output voltage value Vafin (that is, the “air-fuel ratio according to the present invention” corresponding to the input-side air-fuel ratio A / Fin that is the air-fuel ratio of the exhaust (that is, catalyst inflow gas) upstream of the three-way catalyst 220.
  • This is a sensor that outputs an example of “equivalent value”. That is, the air-fuel ratio sensor 221 employs a configuration in which the input-side air-fuel ratio A / Fin is indirectly detected by a voltage value having a unique relationship with the input-side air-fuel ratio A / Fin.
  • the output voltage value Vafin matches the reference output voltage value Vst when the input side air-fuel ratio A / Fin is the stoichiometric air-fuel ratio.
  • the output voltage value Vafin is lower than the reference output voltage value Vst when the input side air-fuel ratio A / Fin is on the air-fuel ratio rich side, and when the input-side air-fuel ratio A / Fin is on the air-fuel ratio lean side. It becomes higher than the reference output voltage value Vst. That is, the output voltage value Vafin continuously changes with respect to the change of the input side air-fuel ratio A / Fin.
  • the air-fuel ratio sensor 221 is electrically connected to the ECU 100, and the detected output voltage value Vafin is referred to by the ECU 100 at a constant or indefinite period.
  • an O 2 sensor 222 that can detect the downstream oxygen concentration Coxs that is the oxygen concentration of the catalyst exhaust gas that has passed through the three-way catalyst 220 is installed.
  • the O 2 sensor 222 is a known electromotive force type oxygen concentration sensor (that is, a concentration cell type oxygen concentration sensor using stabilized zirconia), and is an example of the “second detection means” according to the present invention.
  • the O 2 sensor 222 is a sensor that outputs an output voltage value Voxs (that is, an example of an “air-fuel ratio equivalent value” according to the present invention) corresponding to the downstream oxygen concentration Coxs. That is, the O 2 sensor 222 adopts a configuration in which the oxygen concentration is indirectly detected by a voltage value having a unique relationship with the oxygen concentration.
  • Voxs that is, an example of an “air-fuel ratio equivalent value” according to the present invention
  • the output voltage value Voxs of the O 2 sensor 222 is a reference when the air-fuel ratio of the catalyst exhaust gas is the stoichiometric air-fuel ratio (in other words, when the downstream oxygen concentration Coxs is the reference oxygen concentration Coxsb corresponding to the stoichiometric air-fuel ratio). It corresponds to the output voltage value Voxsb (for example, about 0.5V).
  • the output voltage value Voxs is higher than the reference output voltage value Voxsb when the air-fuel ratio of the catalyst exhaust gas is on the air-fuel ratio rich side with respect to the stoichiometric air-fuel ratio, and when the air-fuel ratio is also on the air-fuel ratio lean side. It becomes lower than the reference output voltage value Voxsb.
  • the output voltage value Voxs of the O 2 sensor 222 is a decrease in the air-fuel ratio (ie, oxygen concentration). With a decrease in Coxs), it increases relatively linearly and substantially linearly to a maximum output voltage value Voxsmax (for example, about 0.9 V) corresponding to the rich-side detection limit air-fuel ratio. In the air-fuel ratio region on the rich side with respect to the rich-side detection limit air-fuel ratio, the output voltage value Voxs is substantially constant at the maximum output voltage value Voxsmax.
  • the output voltage value Voxs of the O 2 sensor 222 increases the air-fuel ratio (that is, the oxygen concentration Coxs increases).
  • a minimum output voltage value Voxsmin for example, about 0.1 V
  • the output voltage value Voxs is substantially constant at the minimum output voltage value Voxsmin.
  • the O 2 sensor 222 is electrically connected to the ECU 100, and the detected output voltage value Voxs is referred to by the ECU 100 at a constant or indefinite period.
  • a water temperature sensor 223 capable of detecting a cooling water temperature Tw, which is a temperature of cooling water (LLC) circulated and supplied to cool the engine 200, is installed in a water jacket installed so as to surround the cylinder block CB. It is arranged.
  • the water temperature sensor 223 is electrically connected to the ECU 100, and the detected cooling water temperature Tw is referred to by the ECU 100 at a constant or indefinite period.
  • the intake pipe 206 is provided with an air flow meter 224 capable of detecting the intake air amount Ga.
  • the air flow meter 224 is electrically connected to the ECU 100, and the detected intake air amount Ga is referred to by the ECU 100 at a constant or indefinite period.
  • the engine 200 according to the present embodiment is a non-supercharged engine using gasoline as a fuel, but the configuration of the internal combustion engine according to the present invention is not limited to the engine 200 and may be various.
  • the internal combustion engine according to the present invention has the number of cylinders, cylinder arrangement, fuel type, fuel injection mode, intake / exhaust system configuration, valve operating system configuration, combustion system, presence / absence of supercharger, supercharging mode, etc.
  • the engine 200 may be different.
  • the engine system 10 may include a diesel engine that is a compression self-ignition internal combustion engine instead of the engine 200, or a direct injection capable of injecting fuel into the cylinder instead of or in addition to the intake port injector 212.
  • You may provide the direct-injection engine provided with the injection injector.
  • lean burn lean combustion
  • a supercharger may be installed in the intake system.
  • the compressor of the supercharger may be configured to be driven by an exhaust turbine, or may be configured to be mechanically driven by engine torque.
  • the construction mode of the catalyst system in the exhaust system may be different if the engine mode is different, the concept of sulfur poisoning recovery control described later can be applied to any configuration.
  • the air-fuel ratio F / B control includes a main F / B control and a sub F / B control.
  • the main F / B control is control of the fuel injection amount so that the input side air-fuel ratio A / Fin obtained based on the output voltage value Vafin of the air-fuel ratio sensor 221 converges to the input side target air-fuel ratio A / Fintg. is there.
  • the sub F / B control is a control for correcting the output voltage value Vafin of the air-fuel ratio sensor 221 or the input side target air-fuel ratio A / Fintg so that the output voltage value Voxs of the O 2 sensor 222 converges to the target output voltage value Voxstg. is there.
  • the target air-fuel ratio is an air-fuel ratio that optimizes the exhaust purification action of the three-way catalyst 220, and is, for example, a theoretical air-fuel ratio.
  • this target air-fuel ratio may be changed as appropriate according to the required performance of the engine 200, etc., as long as it is allowed in consideration of emissions and fuel consumption, and may be changed as appropriate.
  • the ECU 100 In executing the main F / B control and the sub F / B control, the ECU 100 functions as an example of the “air-fuel ratio control means” in the present invention.
  • Various feedback controls based on the values corresponding to the air / fuel ratio upstream and downstream of the catalyst have been proposed in the past, and further details are omitted here for the purpose of preventing complication of explanation.
  • FIG. 2 is a flowchart of the sulfur poisoning recovery control. Note that the sulfur poisoning recovery control is executed by the ECU 100 as a subroutine of the air-fuel ratio F / B control described above.
  • the ECU 100 acquires the sulfur accumulation amount Asf of the three-way catalyst 220 (step S101).
  • the sulfur accumulation amount Asf is the amount of sulfur accumulated in the three-way catalyst 220 during the period from the end of the previous sulfur poisoning recovery control to the present. Is an example.
  • the sulfur accumulation amount Asf is repeatedly calculated by the ECU 100 in a control routine different from the sulfur poisoning recovery control, and is stored in a rewritable memory such as a RAM with appropriate updating. That is, in the process of calculating the sulfur accumulation amount Dsf, the ECU 100 functions as an example of “accumulation amount estimation means” according to the present invention.
  • the ECU 100 estimates the sulfur accumulation amount Dsf from the accumulated fuel consumption amount ⁇ Qpfi that is a value obtained by accumulating the fuel injection amount Qpfi for each cycle of each cylinder. It is assumed that the sulfur content in the unit fuel is given as an initial value in advance.
  • the ECU 100 calculates the sulfur accumulation amount Dsf by multiplying the accumulated fuel consumption amount ⁇ Qpfi at that time by a predetermined accumulation rate ⁇ .
  • the accumulation rate ⁇ is a correction coefficient that represents the ratio of sulfur accumulated in the three-way catalyst 220 among the sulfur discharged to the exhaust pipe 219, and is experimentally, empirically, or theoretically preliminarily experimentally and empirically or theoretically.
  • the load factor KL (that is, the ratio of the fresh air amount taken into the cylinder 201 with respect to the physical maximum value) is stored in the control map as a parameter.
  • the ECU 100 acquires the in-catalyst hydrogen generation amount Ah2cat (step S102).
  • the in-catalyst hydrogen production amount Ah2cat is an integrated amount of hydrogen produced by the three-way catalyst 220 in the period from the end of the previous sulfur poisoning recovery control to the present, Is an example.
  • the in-catalyst hydrogen generation amount Ah2cat is repeatedly calculated by the ECU 100 in a control routine different from the sulfur poisoning recovery control, and stored in a rewritable memory such as a RAM with appropriate updating. That is, in the process of calculating the in-catalyst hydrogen generation amount Ah2cat, the ECU 100 functions as an example of the “in-catalyst generation amount estimation means” according to the present invention.
  • the ECU100 acquires in-catalyst hydrogen production amount Ah2cat based on catalyst bed temperature Tcat of the three-way catalyst 220. More specifically, the ROM of the ECU 100 stores a first hydrogen concentration map that defines the relationship between the catalyst bed temperature Tcat and the hydrogen concentration, and the ECU 100 reads the catalyst bed temperature Tcat from the first hydrogen concentration map. The hydrogen concentration corresponding to is estimated, and the in-catalyst hydrogen generation amount Ah2cat is calculated from the estimated hydrogen concentration.
  • the catalyst bed temperature Tcat is based on the accumulated fuel consumption (conceptually similar to the previous ⁇ Qpfi) after the latest IG ON timing in a control routine different from the sulfur poisoning recovery control. Presumed. Specifically, a control map representing the relationship between the accumulated fuel consumption and the catalyst bed temperature Tcat is stored in advance in the ROM, and the ECU 100 acquires a temperature value corresponding to the accumulated fuel consumption from the control map. As a result, the catalyst bed temperature Tcat is estimated. In addition, when a temperature sensor is arrange
  • FIG. 3 is a conceptual diagram of the first hydrogen concentration map.
  • the vertical axis and the horizontal axis represent the hydrogen concentration and the catalyst bed temperature Tcat in the three-way catalyst 220, respectively.
  • corresponding hydrogen is generated on both the low temperature side and the high temperature side, with a hydrogen deficient region (hatched region) located in the temperature region around 600 ° C. being the boundary.
  • hydrogen deficient region located in the temperature region around 600 ° C. being the boundary.
  • hydrogen is generated mainly by the water gas shift reaction
  • hydrogen is generated mainly by the steam reforming reaction.
  • the hydrogen concentration is because the hydrogen amount depends on the total amount of the catalyst inflow gas flowing into the three-way catalyst 220. That is, the ECU 100 estimates the amount of hydrogen generated in the three-way catalyst 220 per unit time based on the hydrogen concentration acquired from the first hydrogen concentration map, the engine speed NE, and the load factor KL. The estimated amount of hydrogen generated per unit time is accumulated as needed, and the accumulated value is temporarily stored in a storage means such as a RAM.
  • the in-catalyst hydrogen production amount Ah2cat is the stored integrated value.
  • the ECU 100 calculates the corrected accumulation amount Asfcor based on the sulfur accumulation amount Asf acquired in step S101 and the in-catalyst hydrogen generation amount Ah2cat acquired in step S102 (step S103).
  • the corrected accumulation amount Asfcor is an amount obtained by subtracting the reduction amount due to the reduction action of the hydrogen generated in the three-way catalyst 220 from the sulfur accumulated in the three-way catalyst 220. It is the amount of sulfur estimated to be accumulated in.
  • the ECU 100 determines whether or not the calculated corrected accumulation amount Asfcor is larger than the reference value Asfcorth (step S104).
  • the reference value Asfcorth is previously determined experimentally, empirically, or theoretically as a value that reduces the purification efficiency of the three-way catalyst 220 to a predetermined value or more.
  • step S104 the ECU 100 ends the sulfur poisoning recovery control. Since the sulfur poisoning recovery control is a subroutine of the air-fuel ratio F / B control as described above, it is executed again when the execution condition is satisfied in the air-fuel ratio F / B control.
  • step S104 determines that the three-way catalyst 220 needs to be recovered from sulfur poisoning, and performs the processing after step S105. Execute. That is, in this case, the ECU 100 functions as an example of the “determination unit” according to the present invention. Further, the process from step S105 to step S109 is an example of “sulfur poisoning recovery” according to the present invention.
  • step S105 the required H2 amount Nh2 is calculated.
  • the required H2 amount Nh2 is a required amount of hydrogen that needs to be generated in the cylinder 201, and is an example of the “required amount of hydrogen in the cylinder” according to the present invention.
  • the required H2 amount Nh2 is the amount of hydrogen necessary to reduce sulfur corresponding to the corrected accumulation amount Asfcor calculated in step S103, and its calculation algorithm is given experimentally, empirically or theoretically in advance. It has been.
  • the ECU 100 determines the air-fuel ratio imbalance degree IMB in each cylinder (step S106).
  • the air-fuel ratio imbalance degree IMB is an index value of variation in the air-fuel ratio between cylinders, and can be defined in various ways in practice.
  • the air-fuel ratio imbalance degree IMB in this embodiment is defined as a ratio of a deviation between the theoretical air-fuel ratio and the control air-fuel ratio of each cylinder with respect to the theoretical air-fuel ratio. That is, if the theoretical air-fuel ratio is X and the air-fuel ratio of a certain cylinder is Y, the degree of imbalance of the cylinder is (XY) / X ⁇ 100 (%).
  • the imbalance degree of the cylinder is about 32%.
  • the air-fuel ratio of a certain cylinder is 18, the imbalance degree of that cylinder is about ⁇ 23%.
  • the degree of variation in the air-fuel ratio of each cylinder is indirectly expressed through the theoretical air-fuel ratio.
  • the determination of the imbalance degree IMB is equivalent to determining the target value of the air-fuel ratio of each cylinder in the sulfur poisoning recovery control according to the definition.
  • the ECU 100 refers to the second hydrogen concentration map stored in the ROM when determining the imbalance degree IMB of each cylinder.
  • the second hydrogen concentration map will be described with reference to FIG.
  • FIG. 4 is a conceptual diagram of the second hydrogen concentration map.
  • the vertical axis and the horizontal axis represent the hydrogen concentration and the imbalance degree IMB (%), respectively.
  • the degree of imbalance IMB 0 means the stoichiometric air-fuel ratio according to the above-described definition.
  • the concentration of generated hydrogen increases inside the cylinder.
  • the lean misfire limit on the lean side has a smaller margin for the stoichiometric air-fuel ratio than the rich misfire limit on the rich side. Therefore, the range that can be taken as the imbalance degree IMB is wider on the rich side (positive value), and the hydrogen generation by rich combustion has higher controllability.
  • the hydrogen concentration with respect to the imbalance degree IMB also changes with respect to the engine speed NE and the load factor KL.
  • the hydrogen concentration decreases when the engine speed NE is low or the load factor KL is small (see the chain line in the figure).
  • the hydrogen concentration increases (see the broken line in the drawing).
  • the relationship shown in the figure is stored in a numerical state in advance, and the ECU 100 determines the hydrogen concentration with respect to the imbalance degree IMB based on the engine speed NE and the load factor KL at that time. Can be estimated. Further, the total amount of gas discharged from the cylinder per unit time can be estimated based on the engine speed NE and the load factor KL. Therefore, the ECU 100 can calculate the hydrogen generation amount Gh2 in the cylinder 201 in which a certain imbalance degree IMB is selected.
  • the imbalance degree IMB of each cylinder is determined so that the air-fuel ratio of the entire cylinder of the engine 200 matches the input target air-fuel ratio AFintg or the theoretical air-fuel ratio as much as possible. Therefore, when one cylinder 201 is controlled to the air-fuel ratio rich side (or lean side) when imbalance is generated between the cylinders, at least a part of the other cylinders is controlled to the lean side (or rich side). Is done. At this time, the cylinder controlled to the rich side and the cylinder controlled to the lean side alternately reach the combustion stroke in time series so that the fluctuation of the engine torque of the engine 200 is minimized. Thus, the air-fuel ratio of each cylinder may be determined.
  • the combination of the imbalance degree IMB of each cylinder that can maintain the air-fuel ratio at the input side target air-fuel ratio A / Fintg or the stoichiometric air-fuel ratio in the plurality of cylinders as a whole is not unique.
  • the imbalance degree IMB of the remaining cylinders other than the rich cylinder may be determined, or more simply, the average air-fuel ratio of all the cylinders may be determined.
  • the provisional air-fuel ratio of the remaining cylinders may be determined so that the theoretical air-fuel ratio or the input-side target air-fuel ratio A / Fintg is obtained.
  • the latter technique refers to the following, for example.
  • the amount of fuel required to make the average air-fuel ratio of the entire cylinder the stoichiometric air-fuel ratio or the input-side target air-fuel ratio A / Fintg is “10” (that is, one cylinder
  • the fuel amount required for the cycle is “2, 5”).
  • the fuel injection amount of the rich cylinder controlled to the rich side is “4”
  • the fuel amount to be injected in the remaining three cylinders is “6”.
  • the fuel injection amount of each remaining cylinder is set to “2”, or the fuel injection amount is maintained at “2.5” for two of the remaining three cylinders, and the remaining one cylinder Only the fuel injection amount is set to “1”. Even in this case, the fuel injection amount of the entire cylinder is maintained at the target value, and the average air-fuel ratio of the catalyst inflow gas flowing into the three-way catalyst 220 is maintained at the theoretical air-fuel ratio or the input-side target air-fuel ratio A / Fintg. I can do it.
  • the imbalance degree IMB of at least one cylinder 201 is equal to the previously calculated H2 required amount Nh2.
  • H2 required amount Nh2 the previously calculated H2 required amount
  • the air-fuel ratio of as many cylinders as possible is controlled to the rich side or the lean side, and the combustion stroke is rich cylinder ⁇ lean cylinder ⁇ rich cylinder as described above.
  • the imbalance degree IMB of each cylinder is determined so as to maximize the amount of hydrogen generated per unit time. .
  • the ECU 100 switches the target air-fuel ratio of each cylinder according to the determined imbalance degree IMB. (Step S107).
  • the port injector 212 is driven and controlled in accordance with a normal fuel injection control routine, and fuel injection for causing imbalance between cylinders is realized.
  • the ECU 100 counts the hydrogen generation amount ⁇ Gh2 in the entire cylinder after the start of the imbalance control as an integrated value of the hydrogen generation amount Gh2 of each cylinder (step S108). Subsequently, it is determined whether or not the counted hydrogen generation amount ⁇ Gh2 has exceeded the previously calculated H2 required amount Nh2 (step S109). (S109: NO), the process is returned to step S108, and the imbalance control is continued.
  • step S109 When the hydrogen generation amount ⁇ Gh2 becomes larger than the H2 required amount Nh2 (step S109: YES), the ECU 100 controls the sulfur accumulation amount estimation subroutine so that the sulfur accumulation amount Asf is cleared (step S110). End poisoning recovery control.
  • the hydrogen generation amount ⁇ Gh2 and the H2 required amount Nh2 are compared, but hydrogen generation in the three-way catalyst 220 is separately performed even during a period in which hydrogen is generated in the cylinder due to the air-fuel ratio imbalance. proceed. Therefore, the ECU 100 may execute step S109 by adding the in-catalyst hydrogen generation amount Ah2cat to the hydrogen generation amount ⁇ Gh2 during the period of recovery from sulfur poisoning due to the air-fuel ratio imbalance.
  • the H2 required amount Nh2 may be corrected to the decreasing side in consideration of the in-catalyst hydrogen generation amount Ah2cat in calculating the H2 required amount Nh2.
  • the sulfur poisoning of the three-way catalyst 220 is reduced without causing an increase in cost by causing an air-fuel ratio imbalance between the cylinders. It is possible to recover. Further, since the degree of imbalance IMB of each cylinder is determined so that the air-fuel ratio of the entire cylinder becomes the stoichiometric air-fuel ratio or the input-side target air-fuel ratio A / Fintg, the air-fuel ratio of the catalyst inflow gas flowing into the three-way catalyst 220 Is substantially maintained at the theoretical air fuel ratio or the input side target air fuel ratio A / Fintg. Therefore, sulfur poisoning of the three-way catalyst 220 can be efficiently and effectively recovered while suppressing deterioration of exhaust emission and fuel consumption.
  • the intake port injector 212 is used as a device for generating an air-fuel ratio imbalance.
  • the fuel injection device is reasonable and appropriate as this type of device.
  • control amounts include the opening / closing timing of the intake valve and the EGR rate of the EGR device.
  • the intake air amount decreases due to the return of intake air in the vicinity of the valve closing timing IVC. Therefore, if the fuel injection amount is constant, the air-fuel ratio shifts relatively to the rich side.
  • the opening / closing timing of the intake valve 209 can be controlled independently for each cylinder, the air-fuel ratio imbalance can be generated by controlling the opening / closing timing.
  • the engine 200 may more preferably include a mechanism capable of independently controlling the operating angle or valve lift amount of the intake valve 209 or the exhaust valve 215 of each cylinder. If the operating angle or valve lift amount can be controlled independently for each cylinder, a relatively large control range can be obtained for the intake air amount for each cylinder. Therefore, the control range of the air-fuel ratio imbalance can be made relatively large.
  • a mechanism may include, for example, an electromagnetic drive device that opens and closes an intake valve or an exhaust valve for each cylinder.
  • each cylinder may have an intake throttle valve independently. In this case, even if the opening / closing characteristics of the valve are uniform for each cylinder, the intake air amount can be changed for each cylinder. That is, an air-fuel ratio imbalance can be generated.
  • the EGR device can also be used as a device that causes an air-fuel ratio imbalance.
  • the EGR rate can be independently controlled for each cylinder by controlling the open / close state of the EGR valve provided in each EGR pipe. .
  • the ratio of fresh air to in-cylinder intake gas can be changed, and an air-fuel ratio imbalance can be generated.
  • the determination regarding whether or not to perform sulfur poisoning recovery is performed based on the sulfur accumulation amount Asf and the in-catalyst hydrogen generation amount Ah2cat, but this is an example. Yes, the ECU 100 may perform the determination based only on the sulfur accumulation amount Asf. For example, when the sulfur accumulation amount Asf is greater than or equal to a predetermined value, the processing after step S105 may be executed.
  • the ECU 100 may make the determination based only on the in-catalyst hydrogen generation amount Ah2cat. For example, when the amount of hydrogen generated in the catalyst Ah2cat in a predetermined period is equal to or less than a reference value, it is determined that the processing for sulfur poisoning recovery should be performed because the necessity for sulfur poisoning recovery is large. Also good.
  • FIG. 5 is a flowchart of the sulfur poisoning recovery control.
  • the same reference numerals are given to the same portions as those in FIG. 2, and the description thereof will be omitted as appropriate.
  • the ECU 100 calculates the retard amount of the ignition timing by the ignition device 213 (step S201). ).
  • the catalyst bed temperature Tcat affects the amount of hydrogen generated in the three-way catalyst 220 (in-catalyst hydrogen generation amount Ah2cat) as described above.
  • the catalyst bed temperature Tcat also increases in the air-fuel ratio imbalance control accompanied by the enrichment of the air-fuel ratio.
  • the air-fuel ratio imbalance degree IMB as one control element has two hydrogen generation amounts Gh2 and catalyst bed temperature Tcat. The state quantity cannot be controlled independently. Therefore, the retard amount of the ignition timing is used as a control element for controlling the catalyst bed temperature Tcat.
  • the retard amount of the ignition timing is executed, for example, when the execution period of the sulfur poisoning recovery control can be shortened by the retard of the ignition timing.
  • the effect is executed so that the influence can be mitigated by increasing the catalyst bed temperature Tcat.
  • ignition timing retardation control is executed following the target air-fuel ratio switching control (imbalance control) (step S202).
  • the hydrogen generation amount Gh2 in the cylinder and the catalyst bed temperature Tcat can be independently controlled by retarding the ignition timing, the sulfur poisoning of the three-way catalyst 220 is prevented. In the recovery, the combustion state in the cylinder can be made more desirable.
  • the present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist or concept of the invention that can be read from the claims and the entire specification, and the control of the internal combustion engine accompanying such a change.
  • the apparatus is also included in the technical scope of the present invention.
  • the present invention can be applied to sulfur poisoning recovery control of a catalyst in an internal combustion engine.
  • 10 engine system, 100 ... ECU, 200 ... engine, CB ... Cylinder block, 201 ... cylinder, 212 ... intake port injector, 219 ... exhaust pipe, 220 ... three-way catalyst, 221 ... air-fuel ratio sensor, 222 ... O 2 sensor .

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Abstract

The present invention restores a catalyst from a state of sulfur poisoning while minimizing cost increases, increases in exhaust emissions, and decreases in fuel efficiency. This control device (100), which controls an internal combustion engine (200) provided with a plurality of cylinders (201) and an exhaust-purification catalyst (220) installed in an exhaust passage connected to the plurality of cylinders, is provided with the following: a determination means that determines whether or not to perform sulfur-poisoning recovery on the catalyst; and a poisoning-recovery control means that, if it was determined that the aforementioned sulfur-poisoning recovery is to be performed, controls the air-fuel ratio of exhaust gas flowing to the catalyst. The poisoning-recovery control means controls the degree of air-fuel ratio imbalance among the plurality of cylinders.

Description

内燃機関の制御装置Control device for internal combustion engine
　本発明は、排気経路に設置された排気浄化用の触媒を硫黄被毒から回復させるにあたって好適な、内燃機関の制御装置の技術分野に関する。 The present invention relates to a technical field of a control device for an internal combustion engine suitable for recovering an exhaust purification catalyst installed in an exhaust path from sulfur poisoning.
　排気経路に設置される排気浄化用の触媒は、燃料中に不純物として含有される硫黄が触媒に添加される貴金属に吸着して硫黄被毒する。硫黄被毒した状態では、触媒の活性が著しく失われ、触媒本来の排気浄化作用を得られないことから、従来、触媒から硫黄を脱離させるための各種の硫黄被毒回復制御が提案されている。尚、硫黄は、気筒内部又は排気経路で酸化してＳＯｘ（硫黄酸化物）として触媒に吸着することが多く、硫黄の脱離とは、端的には、硫黄の還元を意味する。 The exhaust purification catalyst installed in the exhaust path adsorbs sulfur contained as impurities in the fuel to the noble metal added to the catalyst and poisons the sulfur. In the state of sulfur poisoning, the activity of the catalyst is remarkably lost, and the original exhaust purification action of the catalyst cannot be obtained. Therefore, various sulfur poisoning recovery controls have been proposed for desorbing sulfur from the catalyst. Yes. In many cases, sulfur is oxidized inside the cylinder or in the exhaust path and is adsorbed to the catalyst as SOx (sulfur oxide), and the desorption of sulfur simply means reduction of sulfur.
　例えば、特許文献１には、リーンＮＯｘ触媒における硫黄被毒回復制御が開示されている。特許文献１に開示された内燃機関の排気浄化装置は、リーンＮＯｘ触媒上流側にＨ２（水素）センサを配し、当該Ｈ２センサの出力値に基づいて、筒内のリッチ燃焼が制御される構成となっている。即ち、触媒流入ガスのＨ２濃度をリッチ燃焼の制御量にＦ／Ｂ制御する構成となっており、硫黄被毒回復時に適切な量の水素を供給可能であるとされている。 For example, Patent Document 1 discloses sulfur poisoning recovery control in a lean NOx catalyst. The exhaust gas purification apparatus for an internal combustion engine disclosed in Patent Document 1 includes an H 2 (hydrogen) sensor upstream of the lean NOx catalyst, and rich combustion in the cylinder is controlled based on the output value of the H 2 sensor. It is the composition which becomes. That is, it is configured that the H 2 concentration of the catalyst inflow gas is F / B controlled to a rich combustion control amount, and an appropriate amount of hydrogen can be supplied at the time of sulfur poisoning recovery.
　また、特許文献２には、一部の気筒を空燃比リッチに、残余の気筒を空燃比リーンに制御することによって、触媒の昇温を図る技術も開示されている。 Further, Patent Document 2 discloses a technique for raising the temperature of the catalyst by controlling some cylinders to be rich in the air-fuel ratio and the remaining cylinders to be air-fuel ratio lean.
　また、特許文献３には、ＮＯｘ触媒の硫黄蓄積量が所定値を超えた場合に、触媒上流に搭載されたＨ２供給手段によりＨ２を供給する構成が開示されている。 Patent Document 3 discloses a configuration in which H 2 is supplied by an H 2 supply means mounted upstream of the catalyst when the amount of sulfur accumulated in the NOx catalyst exceeds a predetermined value.
　また、特許文献４には、希薄燃焼エンジンの排気系に、ＣＯ２吸着材とＨ２生成触媒とＮＯｘ触媒とを配し、Ｈ２生成触媒にＣＯを供給し、水生ガスシフト反応により生成されたＨ２を還元剤としてＮＯｘ触媒に送り込む構成が開示されている。 Further, in Patent Document 4, a CO 2 adsorbent, an H 2 generation catalyst, and a NOx catalyst are arranged in an exhaust system of a lean combustion engine, and CO is supplied to the H 2 generation catalyst, which is generated by an aquatic gas shift reaction. A configuration in which H 2 is sent as a reducing agent to the NOx catalyst is disclosed.
　また、特許文献５には、リーンＮＯｘ触媒システムであって、筒内燃焼を制御可能な内燃機関において、ＮＯｘ触媒再生時は、ポスト噴射時期を脱水素反応とクラッキング反応とが反発するタイミングで実施する構成が開示されている。 Further, Patent Document 5 discloses a lean NOx catalyst system, and in an internal combustion engine capable of controlling in-cylinder combustion, when NOx catalyst is regenerated, post-injection timing is performed at a timing when the dehydrogenation reaction and cracking reaction repel each other. The structure to perform is disclosed.
特開２００６－２４２１２４号公報JP 2006-242124 A 特開２００４－２１８５４１号公報JP 2004-218541 A 特開２００２－２３５５２９号公報JP 2002-235529 A 特開２００５－０９０４２６号公報JP-A-2005-090426 特開２００３－１２０３６９号公報JP 2003-120369 A
　上述したように硫黄の脱離には多様なアプローチが存在する。中でも、還元能力が極めて高い水素（Ｈ２）による硫黄の還元は、触媒を昇温させて還元反応の促進を図る二次的なプロセスを必ずとも必要としない点において、極めて有効である。 As described above, there are various approaches to sulfur desorption. Among them, the reduction of sulfur with hydrogen (H 2 ), which has a very high reducing ability, is extremely effective in that it does not necessarily require a secondary process in which the catalyst is heated to promote the reduction reaction.
　しかしながら、硫黄被毒回復のために、例えば水素添加弁等の水素供給手段を排気経路に別途付加する構成とすることは、製造コストの面からすると望ましくない。 However, in order to recover sulfur poisoning, it is not desirable from the viewpoint of manufacturing cost to add a hydrogen supply means such as a hydrogen addition valve to the exhaust path separately.
　また、改質触媒等により触媒で水素を生成する構成としても、触媒における改質反応に、実使用に耐え得る可制御性を与えることは一般的に難しい。それに加えて、改質反応による水素の生成量にも限界があり、必ずしもその時点で必要とされる量が供給され得る保証もない。これは、硫黄の還元を促進する目的から、何らかの手法（例えば、気筒間で空燃比インバランスを生じさせる等の手法）により触媒床温を上昇させたとしても根本的に変わらない。 In addition, even in a configuration in which hydrogen is generated by a catalyst using a reforming catalyst or the like, it is generally difficult to give controllability that can withstand actual use for the reforming reaction in the catalyst. In addition, the amount of hydrogen produced by the reforming reaction is limited, and there is no guarantee that the amount required at that time can be supplied. Even if the catalyst bed temperature is raised by some method (for example, a method of generating an air-fuel ratio imbalance between cylinders) for the purpose of promoting the reduction of sulfur, this does not change fundamentally.
　一方、上述したように、リッチ燃焼により、ある程度の可制御性を伴って水素を生成する構成において、触媒上流側に水素濃度センサを配し、水素を必要量だけ触媒に供給する技術思想は、一見有用である。 On the other hand, as described above, in a configuration in which hydrogen is generated with a certain degree of controllability by rich combustion, a technical idea of providing a hydrogen concentration sensor upstream of the catalyst and supplying only a necessary amount of hydrogen to the catalyst is as follows: At first glance it is useful.
　しかしながら、実践的見地に立つと、現実的制約に律束された車両搭載を前提とした場合において、この種の用途に十分な性能を発揮し得る水素センサは存在しない。また、存在したとしても、触媒を硫黄被毒から回復させるために必要にして十分な水素の量を、単にセンサ出力値のみから導き得るかは、必ずしも明確でない。特許文献１には、係る点について何も言及されていない。 However, from a practical standpoint, there is no hydrogen sensor that can exhibit sufficient performance for this type of application when it is assumed that the vehicle is mounted with realistic constraints. Also, it is not always clear that even if present, the amount of hydrogen necessary and sufficient to recover the catalyst from sulfur poisoning can be derived solely from the sensor output value. Patent Document 1 does not mention anything about this point.
　また、空燃比リッチ側での燃焼（リッチ燃焼）は、硫黄やＮＯｘの還元は別として、排気エミッションの観点からは不利な制御であり、また燃費の悪化を招く点において経済的にも不利な制御である。従って、硫黄の還元のみを目的として、リッチ燃焼を闇雲に安全側（この場合、即ち、水素の生成量が多くなる側）で行うことは合理的でない。 In addition, combustion on the rich side of the air-fuel ratio (rich combustion) is a disadvantageous control from the viewpoint of exhaust emission, apart from the reduction of sulfur and NOx, and is also economically disadvantageous in that it leads to a deterioration in fuel consumption. Control. Therefore, it is not reasonable to perform rich combustion in the dark cloud on the safe side (in this case, that is, on the side where the amount of hydrogen generated increases) for the purpose of reducing only sulfur.
　このように、従来、触媒を硫黄被毒から回復させるための多様な構成又は制御が提案されてはいても、各々一長一短であり、排気エミッション、燃費及びコスト等を含む多様な要求を満たしつつ触媒を硫黄被毒から回復させる制御は、実は未だに存在しない。 Thus, even though various configurations or controls for recovering the catalyst from sulfur poisoning have been proposed in the past, each has its advantages and disadvantages, while satisfying various requirements including exhaust emission, fuel consumption, cost, etc. There is actually no control to recover from sulfur poisoning.
　本発明は、上述した事情に鑑みてなされたものであり、コストの増加並びに排気エミッション及び燃費の悪化を抑制しつつ触媒を硫黄被毒から回復させることが可能な内燃機関の制御装置を提供することを課題とする。 The present invention has been made in view of the above-described circumstances, and provides an internal combustion engine control device capable of recovering a catalyst from sulfur poisoning while suppressing an increase in cost and deterioration of exhaust emission and fuel consumption. This is the issue.
　上述した課題を解決するため、本発明に係る内燃機関の制御装置は、複数の気筒と、前記複数の気筒に繋がる排気経路に設置された排気浄化用の触媒とを備えた内燃機関を制御する、内燃機関の制御装置であって、前記触媒の硫黄被毒回復を実施するか否かを判定する判定手段と、前記硫黄被毒回復を実施すると判定された場合に、前記触媒に流入する排気の空燃比を制御する被毒回復制御手段とを具備し、前記被毒回復制御手段は、前記複数の気筒相互間における前記空燃比のインバランス度を制御することを特徴とする（第１項）。 In order to solve the above-described problem, an internal combustion engine control apparatus according to the present invention controls an internal combustion engine including a plurality of cylinders and an exhaust purification catalyst installed in an exhaust path connected to the plurality of cylinders. A control unit for an internal combustion engine that determines whether or not to perform sulfur poisoning recovery of the catalyst; and exhaust gas that flows into the catalyst when it is determined to perform sulfur poisoning recovery. Poisoning recovery control means for controlling the air-fuel ratio of the plurality of cylinders, wherein the poisoning recovery control means controls the degree of imbalance of the air-fuel ratio among the plurality of cylinders (first item) ).
　本発明に係る内燃機関は、燃料を含む混合気が燃焼する際に生じる熱エネルギを運動エネルギに変換して取り出し可能な機関を包括する概念である。係る概念の範囲において、本発明に係る内燃機関における、気筒数、気筒配列、燃料種別、燃料の噴射態様、吸排気系の構成、動弁系の構成、燃焼方式、過給器の有無及び過給態様等は如何様にも限定されない趣旨である。 The internal combustion engine according to the present invention is a concept encompassing an engine that can convert thermal energy generated when an air-fuel mixture containing fuel burns into kinetic energy and take it out. Within the scope of the concept, in the internal combustion engine according to the present invention, the number of cylinders, the cylinder arrangement, the fuel type, the fuel injection mode, the intake / exhaust system configuration, the valve train configuration, the combustion system, the presence / absence of the supercharger, and the excess The manner of supply is not limited in any way.
　本発明に係る排気浄化用の触媒とは、内燃機関の排気経路に備わり得る各種の触媒を包括する概念であり、好適な一例として、例えば、三元触媒、リーンＮＯｘ触媒（ＮＯｘ吸蔵還元触媒とも称される）、酸化触媒等の実践的形態を採る。 The exhaust purification catalyst according to the present invention is a concept encompassing various types of catalysts that can be provided in the exhaust path of an internal combustion engine. As a suitable example, for example, a three-way catalyst, a lean NOx catalyst (also referred to as a NOx storage reduction catalyst). Practical forms such as oxidation catalyst.
　触媒は、内燃機関の実稼動期間に応じて、燃料中に不純物として含有される硫黄により被毒する。触媒の硫黄被毒は触媒活性を低下させるから、然るべきタイミングで触媒から硫黄を脱離する（即ち、触媒を硫黄被毒から回復させる）必要がある。本発明に係る内燃機関の制御装置では、硫黄被毒回復を実施するか否かが判定手段により判定される。尚、「硫黄被毒回復」とは触媒を硫黄被毒状態から回復させるための制御、処理及び措置を包括する概念である。 The catalyst is poisoned by sulfur contained as an impurity in the fuel according to the actual operation period of the internal combustion engine. Since sulfur poisoning of the catalyst reduces the catalytic activity, it is necessary to desorb sulfur from the catalyst at the appropriate timing (that is, to recover the catalyst from sulfur poisoning). In the control apparatus for an internal combustion engine according to the present invention, it is determined by the determining means whether or not to perform sulfur poisoning recovery. “Sulfur poisoning recovery” is a concept encompassing control, processing and measures for recovering the catalyst from the sulfur poisoning state.
　判定手段が硫黄被毒回復を実施するか否かを判定するにあたっての判定基準は多義的である。例えば、実践的には、硫黄被毒の度合いが所定レベルを超えたとみなされ得るタイミングで硫黄被毒回復を実施することは有効であるが、硫黄被毒回復措置を講じるタイミングはこれに限定されない。即ち、判定手段は、内燃機関が稼動してからの経過時間が所定値を超えた場合に硫黄被毒回復を実施する旨判定してもよいし、より流動的には、内燃機関が定常的運転状態にある適当なタイミングで硫黄被毒回復を実施する旨判定してもよい。即ち、硫黄被毒回復は、触媒の硫黄被毒のレベルに拠らず有効である。 判定 The criteria for determining whether or not the determination means implements sulfur poisoning recovery is ambiguous. For example, in practice, it is effective to perform sulfur poisoning recovery at a timing at which the degree of sulfur poisoning can be considered to have exceeded a predetermined level, but the timing at which sulfur poisoning recovery measures are taken is not limited to this. . That is, the determination means may determine that the sulfur poisoning recovery is performed when the elapsed time after the internal combustion engine has been operated exceeds a predetermined value, or more fluidly, the internal combustion engine is stationary. It may be determined that the sulfur poisoning recovery is performed at an appropriate timing in the operating state. That is, the recovery from sulfur poisoning is effective regardless of the level of sulfur poisoning of the catalyst.
　硫黄被毒した触媒から硫黄（或いは硫黄酸化物）を脱離させるにあたって、水素（Ｈ２）はその極めて高い還元能力から有効であることが知られている。本発明に係る内燃機関の制御装置では、この点に鑑み、被毒回復制御手段によって、触媒に流入する排気（以下、適宜「触媒流入ガス」と表現する）の空燃比が制御される。より具体的には、被毒回復制御手段は、複数の気筒相互間における空燃比のインバランス度を制御する構成となっている。 It is known that hydrogen (H 2 ) is effective due to its extremely high reducing ability in desorbing sulfur (or sulfur oxides) from a sulfur poisoned catalyst. In view of this point, the control apparatus for an internal combustion engine according to the present invention controls the air-fuel ratio of the exhaust gas flowing into the catalyst (hereinafter referred to as “catalyst inflow gas” as appropriate) by the poisoning recovery control means. More specifically, the poisoning recovery control means is configured to control the degree of air-fuel ratio imbalance among a plurality of cylinders.
　気筒内部でリッチ燃焼を行うと、不完全燃焼物である一酸化炭素が水と反応する水性ガスシフト反応及び未燃物である炭化水素が水と反応する水蒸気改質反応により、気筒の内部において水素が生成される。 When rich combustion is performed inside the cylinder, hydrogen is generated inside the cylinder by a water gas shift reaction in which carbon monoxide, which is an incomplete combustion product, reacts with water, and a steam reforming reaction, in which hydrocarbon, an unburned product, reacts with water. Is generated.
　ここで、あるサイクルにおいて、気筒が、空燃比リッチ側の気筒と空燃比リーン側の気筒とに分けられ、気筒相互間で空燃比のインバランスが生じると、このインバランスの度合いとしてのインバランス度により、気筒内における水素生成量を制御することが出来る。 Here, when a cylinder is divided into an air-fuel ratio rich side cylinder and an air-fuel ratio lean side cylinder in a certain cycle, and an air-fuel ratio imbalance occurs between the cylinders, the imbalance as the degree of imbalance Depending on the degree, the amount of hydrogen produced in the cylinder can be controlled.
　このようにインバランス度の制御により気筒の内部において水素を生成する構成とすれば、好適な一形態として、常に一サイクルにおける全気筒の平均空燃比を所望の値（例えば、理論空燃比相当値）に維持することが出来る。即ち、気筒毎に空燃比を個別に制御する必要が生じるものの、見掛け上、触媒流入ガスの空燃比を硫黄被毒回復の非実施時から変化させることなく、触媒に水素を供給することが出来る。従って、トルク変動によるドライバビリティや動力性能の低下及びエミッションや燃費の悪化を好適に抑制することが出来る。 Thus, if it is set as the structure which produces | generates hydrogen inside a cylinder by control of an imbalance degree, as a suitable form, the average air fuel ratio of all the cylinders in one cycle is always desired value (for example, theoretical air fuel ratio equivalent value). ) Can be maintained. That is, although it is necessary to individually control the air-fuel ratio for each cylinder, it is possible to supply hydrogen to the catalyst without apparently changing the air-fuel ratio of the catalyst inflow gas from when sulfur poisoning recovery is not performed. . Therefore, drivability and power performance deterioration due to torque fluctuation, and emission and fuel consumption deterioration can be suitably suppressed.
　また、空燃比のインバランス度は、内燃機関の燃焼プロセスを制御する過程において制御することが出来るから、触媒に水素を供給するにあたって、コストの増加を招く水素添加装置等が必要とされない。即ち、本発明に係る内燃機関の制御装置は、コストの増加を回避し得る点においても実践上の利益が大である。 Further, since the degree of imbalance of the air-fuel ratio can be controlled in the process of controlling the combustion process of the internal combustion engine, a hydrogen addition device or the like that causes an increase in cost is not required when supplying hydrogen to the catalyst. That is, the control device for an internal combustion engine according to the present invention has a great practical advantage in that an increase in cost can be avoided.
　尚、本発明における「空燃比のインバランス度」とは、複数の気筒相互間の空燃比のインバランスの度合いを意味する定量的な指標であり、その実践的態様は、係る概念の範囲において多義的である。また、空燃比のインバランス度は、実践上の定義に応じて、内燃機関に対し一つ定められる値であってもよいし、各気筒について定められる値であってもよい。 The “air-fuel ratio imbalance” in the present invention is a quantitative index that means the degree of air-fuel ratio imbalance among a plurality of cylinders, and its practical aspect is within the scope of the concept. Ambiguous. Further, the degree of imbalance of the air-fuel ratio may be a value determined for the internal combustion engine or a value determined for each cylinder according to a practical definition.
　本発明に係る「空燃比のインバランス度」は、例えば下記（１）～（４）に定義されるものを含み得る。尚、下記の「相当する値」とは、対象値と一義的な関係を有し得る制御量、物理量又は指標値を包括する概念である。
（１）全気筒の空燃比の平均値に対する各気筒の空燃比の割合に相当する値
（２）特定の気筒の空燃比の、残余の気筒の空燃比に対する割合に相当する値
（３）目標空燃比に対する、目標空燃比と各気筒の空燃比との偏差の割合に相当する値
（４）目標空燃比に対する各気筒の空燃比の割合に相当する値
　尚、インバランス度が制御されるにあたって、空燃比リッチ側の気筒と空燃比リーン側の気筒とは固定されていないのが望ましい。理想的には、一の硫黄被毒回復サイクル内において、又は複数の硫黄被毒回復サイクル間において、気筒の平均的な空燃比の気筒相互間の偏差は小さい方がよい。空燃比リッチ側の気筒が常に固定されていると、硫黄被毒回復が繰り返される毎に、気筒毎に筒内状態のばらつきを生じ得るためである。 The “degree of air-fuel ratio imbalance” according to the present invention may include, for example, those defined in (1) to (4) below. Note that the “corresponding value” below is a concept that includes a control amount, a physical amount, or an index value that can have a unique relationship with the target value.
(1) A value corresponding to the ratio of the air-fuel ratio of each cylinder to the average value of the air-fuel ratio of all cylinders (2) A value corresponding to the ratio of the air-fuel ratio of a specific cylinder to the air-fuel ratio of the remaining cylinders (3) Target A value corresponding to the ratio of the deviation between the target air-fuel ratio and the air-fuel ratio of each cylinder with respect to the air-fuel ratio (4) A value corresponding to the ratio of the air-fuel ratio of each cylinder with respect to the target air-fuel ratio It is desirable that the air-fuel ratio rich side cylinder and the air-fuel ratio lean side cylinder are not fixed. Ideally, the deviation between the cylinders in the average air-fuel ratio of a cylinder should be small within one sulfur poisoning recovery cycle or between a plurality of sulfur poisoning recovery cycles. This is because if the cylinder on the air-fuel ratio rich side is always fixed, the in-cylinder state of each cylinder may vary every time the sulfur poisoning recovery is repeated.
　本発明に係る内燃機関の制御装置の一の態様では、前記触媒における硫黄の蓄積量を推定する蓄積量推定手段を更に具備し、前記判定手段は、前記推定された蓄積量に基づいて前記硫黄被毒回復を実施するか否かを判定する（第２項）。 In one aspect of the control apparatus for an internal combustion engine according to the present invention, the control apparatus further includes an accumulation amount estimation unit that estimates an accumulation amount of sulfur in the catalyst, and the determination unit is configured to determine the sulfur based on the estimated accumulation amount. It is determined whether or not poisoning recovery is carried out (2nd term).
　この態様によれば、蓄積量推定手段により、触媒における硫黄の蓄積量が推定され、この推定された蓄積量が判定手段による硫黄被毒回復の実施の有無判定に利用される。従って、触媒がある程度硫黄被毒した段階で的確に硫黄被毒からの回復を図ることができ、効率的である。 According to this aspect, the accumulated amount estimating means estimates the accumulated amount of sulfur in the catalyst, and the estimated accumulated amount is used to determine whether or not the sulfur poisoning recovery is performed by the determining means. Therefore, the catalyst can be accurately recovered from the sulfur poisoning at a stage where the sulfur poisoning to some extent is efficient.
　尚、蓄積量推定手段により推定される「蓄積量」とは、物理的な堆積量や付着量、化学的吸着プロセスを伴う吸着量等を包含し、触媒に対する硫黄の被毒プロセス（触媒に応じて必ずしも一義的でない）に応じて、その表現は多様であってよい。 The “accumulation amount” estimated by the accumulation amount estimation means includes physical accumulation amount, adhesion amount, adsorption amount accompanied by chemical adsorption process, etc., and sulfur poisoning process (depending on the catalyst). The expressions may vary.
　また、触媒における硫黄の蓄積量を推定するにあたっては、公知の各種方法を適用可能である。例えば、蓄積量は、機関回転数、吸気圧、アクセル開度、吸入空気量、スロットル開度、負荷率及び燃料噴射量の少なくとも一部を含み得る内燃機関の運転パラメータと、予め実験的に、経験的に又は理論的に構築された、当該運転パラメータ及び硫黄生成量の相互関係とに基づいて推定されてもよい。この際、内燃機関の排気経路に単位時間当たりに排出される硫黄又は硫黄酸化物（ＳＯｘ）の量が積算され、この積算値から蓄積量が推定されてもよい。また、この積算値と実際の蓄積量との関係（即ち、気筒から排出される硫黄又は硫黄酸化物の全てが触媒に堆積する訳ではない）が明らかである場合には、当該関係が更に参照されてもよい。 In addition, various known methods can be applied to estimate the amount of sulfur accumulated in the catalyst. For example, the accumulated amount is an experimental value in advance of an internal combustion engine operating parameter that may include at least part of the engine speed, intake pressure, accelerator opening, intake air amount, throttle opening, load factor, and fuel injection amount. It may be estimated based on the correlation between the operating parameter and the amount of sulfur production, which is established empirically or theoretically. At this time, the amount of sulfur or sulfur oxide (SOx) discharged per unit time in the exhaust path of the internal combustion engine may be integrated, and the accumulated amount may be estimated from this integrated value. In addition, when the relationship between the integrated value and the actual accumulated amount is clear (that is, not all sulfur or sulfur oxide discharged from the cylinder is deposited on the catalyst), the relationship is further referred to. May be.
　本発明に係る内燃機関の制御装置の他の態様では、前記触媒における水素の生成量を推定する触媒内生成量推定手段を更に具備し、前記判定手段は、前記推定された触媒における水素の生成量に基づいて前記硫黄被毒回復を実施するか否かを判定する（第３項）。 In another aspect of the control device for an internal combustion engine according to the present invention, the control device further includes in-catalyst production amount estimation means for estimating a production amount of hydrogen in the catalyst, and the determination means generates hydrogen in the estimated catalyst. It is determined whether or not the sulfur poisoning recovery is performed based on the amount (Section 3).
　本発明に係る内燃機関の制御装置は、気筒の内部で生成された水素を触媒に供給することにより硫黄被毒からの回復を図る技術思想を有するが、水素は、触媒の構成や種別によっては、触媒においても生成される。触媒で生成される水素と気筒の内部で生成される水素とは硫黄を被毒から回復させる観点からすれば区別されないから、硫黄被毒回復を実施するか否かを判定するにあたっては、触媒における水素の生成量が考慮されるのが望ましい。この態様によれば、触媒内生成量推定手段により、触媒における水素の生成量が推定され、判定手段が硫黄被毒回復を実施するか否かを判定するに際して、この推定結果が考慮される。 The control device for an internal combustion engine according to the present invention has a technical idea of recovering from sulfur poisoning by supplying hydrogen generated in the cylinder to the catalyst. However, depending on the configuration and type of the catalyst, It is also produced in the catalyst. Since hydrogen produced by the catalyst and hydrogen produced inside the cylinder are not distinguished from the viewpoint of recovering sulfur from poisoning, in determining whether to perform sulfur poisoning recovery, It is desirable to consider the amount of hydrogen produced. According to this aspect, the amount of hydrogen produced in the catalyst is estimated by the in-catalyst generation amount estimation means, and this estimation result is taken into account when the determination means determines whether or not to perform sulfur poisoning recovery.
　このため、例えば、触媒において十分に水素が生成され得る状況においては、この触媒において生成された水素により触媒を硫黄被毒から適度に回復させ得る点に鑑みて、気筒内において生成される水素を利用した硫黄被毒回復が不要であるとの判定を適宜下すことができる。或いは、触媒において十分に水素が生成されない状況においては、硫黄被毒の回復に触媒において生成された水素を十分に利用できないことから、気筒内において生成される水素を利用した硫黄被毒回復がより必要であるとの判定を適宜下すことができる。従って、硫黄被毒回復制御手段による硫黄被毒回復の実施タイミング、実施頻度及び実施規模を、実情に即してより最適に維持することが出来る。 For this reason, for example, in a situation where hydrogen can be sufficiently generated in the catalyst, in view of the point that the catalyst can be appropriately recovered from sulfur poisoning by the hydrogen generated in the catalyst, the hydrogen generated in the cylinder is reduced. It is possible to appropriately determine that the used sulfur poisoning recovery is unnecessary. Alternatively, in a situation where hydrogen is not sufficiently generated in the catalyst, hydrogen generated in the catalyst cannot be fully used for recovery of sulfur poisoning, so that sulfur poisoning recovery using hydrogen generated in the cylinder is more effective. A determination that it is necessary can be made as appropriate. Therefore, the execution timing, the execution frequency, and the implementation scale of the sulfur poisoning recovery by the sulfur poisoning recovery control means can be more optimally maintained according to the actual situation.
　尚、触媒における水素の生成量は、例えば予め実験的に、経験的に又は理論的に、内燃機関の各種運転条件をパラメータとして決定しておくことができ、例えば判定手段が適宜参照可能な制御マップにデータとして可能しておくことが出来る。或いは、触媒における水素生成プロセスを演算アルゴリズム化し、その時点の内燃機関の運転条件等に基づいて瞬時的な水素生成量を求めると共に、係る瞬時的生成量を所定期間について積算することによって、触媒における水素生成量を推定してもよい。 The amount of hydrogen produced in the catalyst can be determined in advance, for example, experimentally, empirically, or theoretically, using various operating conditions of the internal combustion engine as parameters. It can be made available as data on the map. Alternatively, the hydrogen generation process in the catalyst is converted into an arithmetic algorithm, the instantaneous hydrogen generation amount is obtained based on the operating conditions of the internal combustion engine at that time, and the instantaneous generation amount is integrated for a predetermined period, thereby The amount of hydrogen generation may be estimated.
　尚、この態様では、前記触媒内生成量推定手段は、前記触媒における水素の生成量として、水性ガスシフト反応及び水蒸気改質反応による水素の生成量を推定してもよい。 In this aspect, the in-catalyst production amount estimation means may estimate the production amount of hydrogen by the water gas shift reaction and the steam reforming reaction as the production amount of hydrogen in the catalyst.
　触媒における水素の生成量は、触媒の種類に応じて異なるものの、基本的には触媒床温に応じて変化する。例えば、三元触媒を例に採ると、約６００～７００℃付近の温度領域を境界として、低温側で水性ガスシフト反応（ＣＯ＋Ｈ２Ｏ→Ｈ２＋ＣＯ２）により、また高温側で水蒸気改質反応（ＨＣ＋Ｈ２Ｏ→Ｈ２＋ＣＯ）により、夫々水素が発生することが知られている。従って、この態様によれば、触媒における水素生成量を必要にして十分な精度で推定することが出来る。尚、具体的には、これらの反応が触媒床温と大きく関係する点に鑑み、各反応による水素生成量又は水素濃度と触媒床温とを対応付ける演算式や制御マップ等が予め用意されていてもよい。 The amount of hydrogen produced in the catalyst varies depending on the type of catalyst, but basically varies depending on the catalyst bed temperature. For example, taking a three-way catalyst as an example, the water temperature shift reaction (CO + H 2 O → H 2 + CO 2 ) is performed on the low temperature side and the steam reforming reaction on the high temperature side with a temperature range of about 600 to 700 ° C. as a boundary. It is known that hydrogen is generated by (HC + H 2 O → H 2 + CO). Therefore, according to this aspect, the amount of hydrogen produced in the catalyst is required and can be estimated with sufficient accuracy. Specifically, in consideration of the fact that these reactions are largely related to the catalyst bed temperature, an arithmetic expression, a control map, and the like are prepared in advance for associating the hydrogen generation amount or hydrogen concentration by the reaction with the catalyst bed temperature. Also good.
　本発明に係る内燃機関の制御装置の他の態様では、前記触媒における硫黄の蓄積量を推定する蓄積量推定手段と、前記触媒における水素の生成量を推定する触媒内生成量推定手段とを具備し、前記判定手段は、前記推定された触媒における硫黄の蓄積量と前記推定された触媒における水素の生成量とに基づいて前記硫黄被毒回復を実施するか否かを判定する（第５項）。 In another aspect of the control device for an internal combustion engine according to the present invention, there is provided an accumulation amount estimation means for estimating an accumulation amount of sulfur in the catalyst and an in-catalyst production amount estimation means for estimating an amount of hydrogen generation in the catalyst. The determination means determines whether or not to perform the sulfur poisoning recovery based on the estimated sulfur accumulation amount in the catalyst and the estimated hydrogen generation amount in the catalyst (Section 5). ).
　この態様によれば、先に述べたものと同等の蓄積量推定手段により推定された硫黄の蓄積量と、上述したものと同等の触媒内生成量推定手段により推定された触媒における水素の生成量とに基づいて硫黄被毒回復を実施するか否かが判定される。例えば、推定された触媒における水素の生成量から硫黄の反応量を計算し、推定された硫黄の蓄積量からこの計算された反応量を減じてなる差分値が所定値以上である場合等に、硫黄被毒回復を実施するとの判定が下される。 According to this aspect, the sulfur accumulation amount estimated by the accumulation amount estimation means equivalent to that described above, and the hydrogen production amount estimated by the in-catalyst production amount estimation means equivalent to those described above Based on the above, it is determined whether or not to perform sulfur poisoning recovery. For example, when the reaction amount of sulfur is calculated from the estimated amount of hydrogen generated in the catalyst, and the difference value obtained by subtracting the calculated reaction amount from the estimated amount of accumulated sulfur is a predetermined value or more, etc. A decision is made to implement sulfur poisoning recovery.
　従って、単に硫黄の蓄積量のみに基づいて判定を行う場合と較べて、実際の触媒の状態をより反映した判定を行うことができる。その結果、必ずしも気筒の内部において生成された水素を必要としない状況において、気筒相互間の空燃比インバランスを伴う被毒回復制御手段による硫黄被毒回復が実施されることを防止することができる。 Therefore, it is possible to make a determination that more reflects the actual state of the catalyst as compared with a case where the determination is based solely on the amount of accumulated sulfur. As a result, it is possible to prevent the sulfur poisoning recovery from being performed by the poisoning recovery control means accompanied with the air-fuel ratio imbalance between the cylinders in a situation where hydrogen generated in the cylinder is not necessarily required. .
　本発明に係る内燃機関の制御装置の他の態様では、前記触媒における硫黄の蓄積量を推定する蓄積量推定手段と、前記触媒における水素の生成量を推定する触媒内生成量推定手段と、前記推定された硫黄の蓄積量と、前記推定された触媒における水素の生成量とに基づいて、前記気筒における水素の要求量を推定する要求量推定手段と、前記インバランス度の制御による前記気筒における水素の生成量を推定する筒内生成量推定手段とを具備し、前記被毒回復制御手段は、前記推定された要求量が得られるように前記推定された気筒における水素の生成量に基づいて前記インバランス度を制御する（第６項）。 In another aspect of the control apparatus for an internal combustion engine according to the present invention, an accumulation amount estimation means for estimating the amount of sulfur accumulation in the catalyst, an in-catalyst production amount estimation means for estimating the amount of hydrogen production in the catalyst, Based on the estimated amount of accumulated sulfur and the estimated amount of hydrogen generated in the catalyst, the required amount estimating means for estimating the required amount of hydrogen in the cylinder, and in the cylinder by controlling the degree of imbalance An in-cylinder generation amount estimation means for estimating the amount of hydrogen generation, and the poisoning recovery control means is based on the estimated hydrogen generation amount in the cylinder so as to obtain the estimated required amount. The degree of imbalance is controlled (sixth term).
　上述したように気筒全体の平均的な空燃比を目標空燃比に維持し得るとは言え、個々の気筒についてみれば、被毒回復制御手段による空燃比のインバランス度の制御は、燃焼状態を理想的な燃焼状態から乖離させることによって実現される。従って、触媒を硫黄被毒から回復させるための、気筒の内部における水素の生成量は、触媒の硫黄被毒を回復させるのに必要にして十分な量であるのが望ましい。 Although the average air-fuel ratio of the entire cylinder can be maintained at the target air-fuel ratio as described above, the control of the air-fuel ratio imbalance degree by the poisoning recovery control means is the combustion state of the individual cylinders. Realized by deviating from the ideal combustion state. Therefore, it is desirable that the amount of hydrogen generated inside the cylinder for recovering the catalyst from sulfur poisoning is an amount necessary and sufficient to recover the sulfur poisoning of the catalyst.
　この態様によれば、蓄積量推定手段により推定される硫黄の蓄積量と、触媒内生成量推定手段により推定される触媒における水素の生成量とに基づいて、要求量推定手段が気筒における水素の要求量を推定する。尚、要求量とは、重量や体積等といった典型的な量的指標の他に、単位時間或いは単位体積当たりの重量や体積等として定義される濃度等を含む概念である。 According to this aspect, based on the sulfur accumulation amount estimated by the accumulation amount estimation unit and the hydrogen generation amount in the catalyst estimated by the in-catalyst generation amount estimation unit, the request amount estimation unit determines the hydrogen content in the cylinder. Estimate the required amount. The required amount is a concept including a concentration defined as weight or volume per unit time or unit volume in addition to typical quantitative indicators such as weight and volume.
　要求量推定手段は、例えば、蓄積量推定手段により推定される蓄積量から、触媒内生成量推定手段により推定される、触媒における水素の生成量を差し引き、被毒回復制御手段によるインバランス度の制御により生成させるべき水素の要求量を推定してもよい。或いは、要求量推定手段は、例えば、蓄積量推定手段により推定される蓄積量を、触媒内生成量推定手段により推定される触媒における水素の生成量に応じて減算側に補正する等して当該要求量を推定してもよい。 For example, the required amount estimating means subtracts the amount of hydrogen generated in the catalyst estimated by the in-catalyst generation amount estimating means from the accumulated amount estimated by the accumulated amount estimating means, and determines the degree of imbalance by the poisoning recovery control means. The required amount of hydrogen to be generated by control may be estimated. Alternatively, the required amount estimation means, for example, corrects the accumulation amount estimated by the accumulation amount estimation means to the subtraction side according to the hydrogen production amount in the catalyst estimated by the in-catalyst production amount estimation means, etc. The required amount may be estimated.
　一方、この態様によれば、筒内生成量推定手段により、インバランス度の制御により気筒において生成される水素の量が推定される。尚、気筒において生成される水素の量とは、重量や体積等といった典型的な量的指標の他に、単位時間或いは単位体積当たりの重量や体積等として定義される濃度等を含む概念である。尚、本発明に係る内燃機関の制御装置では、インバランス度の制御により気筒における水素の生成量を制御する構成を採ることから、インバランス度と気筒において生成される水素量又は生成される水素に応じた水素濃度との関係が、予め実験的に、経験的に又は理論的に与えられている。 On the other hand, according to this aspect, the in-cylinder generation amount estimation means estimates the amount of hydrogen generated in the cylinder by controlling the degree of imbalance. The amount of hydrogen generated in the cylinder is a concept including a concentration defined as a unit time or a weight or volume per unit volume, in addition to a typical quantitative index such as weight or volume. . The control device for an internal combustion engine according to the present invention employs a configuration in which the amount of hydrogen produced in the cylinder is controlled by controlling the degree of imbalance, so that the degree of imbalance and the amount of hydrogen produced in the cylinder or the amount of hydrogen produced The relationship with the hydrogen concentration according to is given experimentally, empirically or theoretically in advance.
　気筒における水素の要求量と気筒における水素の生成量とが推定されると、被毒回復制御手段により、この推定された要求量が得られるように、この推定された気筒における水素の生成量に基づいてインバランス度が制御される。この際、インバランス度の実践的制御態様は多様であってよい。例えば、この推定される要求量に応じてインバランス度が決定される場合には、推定される気筒における水素の生成量から硫黄被毒回復の実施時間が定められてもよい。或いは、この推定される要求量とは別に、硫黄被毒回復を実施可能な期間に制限がある場合には、当該期間内に触媒が硫黄被毒から回復するように、インバランス度の目標値が決定されてもよい。 When the required amount of hydrogen in the cylinder and the amount of hydrogen generated in the cylinder are estimated, the estimated amount of hydrogen generated in the cylinder is determined so that the estimated recovery amount is obtained by the poisoning recovery control means. The degree of imbalance is controlled based on this. At this time, the practical control mode of the imbalance degree may be various. For example, when the degree of imbalance is determined according to the estimated required amount, the sulfur poisoning recovery time may be determined from the estimated hydrogen generation amount in the cylinder. Alternatively, if there is a limit to the period during which sulfur poisoning recovery can be performed separately from the estimated required amount, the target value of the imbalance degree is set so that the catalyst recovers from sulfur poisoning within the period. May be determined.
　この態様によれば、被毒回復制御手段による、気筒における水素の生成量を、触媒の硫黄被毒の度合いに応じて常に最適化することができ、コストの増加並びにエミッション及び燃費の悪化を抑制しつつ、触媒を硫黄被毒から回復させることが出来る。例えば、触媒における硫黄の蓄積量のみに応じて気筒における水素の要求量を推定してしまうと、触媒における水素の生成量の分だけ触媒に供給される水素が過多となる。即ち、触媒に対する水素の供給量が必要にして十分な量よりも多くなり、内燃機関の燃焼状態が理想的な燃焼状態から乖離する時間が不要に長くなって、排気エミッションや燃費の悪化が顕在化する。本態様では、このような事態が回避される。 According to this aspect, the amount of hydrogen generated in the cylinder by the poisoning recovery control means can always be optimized according to the degree of sulfur poisoning of the catalyst, and the increase in cost and the deterioration of emission and fuel consumption are suppressed. However, the catalyst can be recovered from sulfur poisoning. For example, if the required amount of hydrogen in the cylinder is estimated according to only the amount of sulfur accumulated in the catalyst, the amount of hydrogen supplied to the catalyst becomes excessive by the amount of hydrogen produced in the catalyst. In other words, the amount of hydrogen supplied to the catalyst is larger than necessary and sufficient, and the time for the combustion state of the internal combustion engine to deviate from the ideal combustion state becomes unnecessarily long, and exhaust emissions and fuel consumption deteriorate. Turn into. In this aspect, such a situation is avoided.
　尚、この態様では、前記触媒内生成量推定手段は、前記インバランス度の制御により変化する前記触媒の温度に基づいて、前記触媒における水素の生成量を推定してもよい（第７項）。 In this aspect, the in-catalyst generation amount estimation means may estimate the amount of hydrogen generation in the catalyst based on the temperature of the catalyst that changes due to the control of the imbalance degree (Seventh Item). .
　空燃比をインバランスさせると、上述した気筒における水素の生成効果とは別に、リッチ側の気筒から排出されるＨＣ或いはＣＯといった未燃成分の一部が、リーン側の気筒から排出される過剰な酸素により、排気経路或いは触媒において燃焼する。このため、触媒床温が上昇する。触媒床温は、触媒における水素生成量と関係があり、その関係性については、予め実験的に、経験的に又は理論的に定めておくことが出来る。 When the air-fuel ratio is imbalanced, in addition to the hydrogen generation effect in the cylinder described above, a part of unburned components such as HC or CO discharged from the rich cylinder are excessively discharged from the lean cylinder. Oxygen burns in the exhaust path or catalyst. For this reason, the catalyst bed temperature rises. The catalyst bed temperature is related to the amount of hydrogen produced in the catalyst, and the relationship can be determined experimentally, empirically or theoretically in advance.
　この態様によれば、触媒内生成量推定手段が、このような触媒床温の上昇作用を勘案して触媒における水素生成量を推定する。ここで、推定された触媒における水素生成量がインバランス度の制御に反映される点に鑑みると、このインバランスの結果から触媒における水素生成量を推定する構成は一種の循環参照となって、一見して論理的整合性を欠く。しかしながら、被毒回復制御手段によるインバランス度の制御は、リアルタイムに変化する触媒の硫黄蓄積量を参照して、望ましくは硫黄蓄積量が十分に低減されるまで継続されるから、硫黄蓄積量の残量を計算するにあたって、インバランス度の制御により変化した触媒床温の影響を反映させることは実践上問題なく可能である。 According to this aspect, the in-catalyst generation amount estimation means estimates the hydrogen generation amount in the catalyst in consideration of such an action of increasing the catalyst bed temperature. Here, in view of the fact that the estimated hydrogen production amount in the catalyst is reflected in the control of the imbalance degree, the configuration for estimating the hydrogen production amount in the catalyst from the result of the imbalance is a kind of circulation reference. At first glance it lacks logical consistency. However, the imbalance control by the poisoning recovery control means is preferably continued until the sulfur accumulation amount is sufficiently reduced with reference to the sulfur accumulation amount of the catalyst that changes in real time. In calculating the remaining amount, it is practically possible to reflect the influence of the catalyst bed temperature changed by controlling the imbalance degree.
　或いは、硫黄被毒回復に適した触媒床温の目標値を定めておき、触媒床温を係る目標値に維持し得るようにインバランス度を制御した上で、気筒における水素生成量と、触媒における水素生成量とが勘案された最適な時間だけ硫黄被毒回復を実施する構成としてもよい。 Alternatively, a target value of the catalyst bed temperature suitable for sulfur poisoning recovery is determined, and the degree of imbalance is controlled so that the catalyst bed temperature can be maintained at the target value. The sulfur poisoning recovery may be performed for an optimal time considering the amount of hydrogen produced in
　或いは更に、触媒床温の上昇による触媒における水素生成量の変化を考慮した上で、インバランス度の目標値を定め、被毒回復制御手段がインバランス度を制御する構成としてもよい。 Alternatively, the target value of the imbalance degree may be determined in consideration of a change in the amount of hydrogen generated in the catalyst due to an increase in the catalyst bed temperature, and the poisoning recovery control means may control the imbalance degree.
　本発明に係る内燃機関の制御装置の他の態様では、前記内燃機関は、前記触媒に流入する排気の空燃比相当値を検出する第１検出手段と、前記触媒から排出される排気の空燃比相当値を検出する第２検出手段とを更に具備し、前記内燃機関の制御装置は、前記検出される触媒に流入する排気の空燃比相当値及び前記検出される触媒から排出される排気の空燃比相当値に基づいて、前記触媒の内部の空燃比を目標空燃比に収束させる空燃比制御手段を更に具備する（第８項）。 In another aspect of the control apparatus for an internal combustion engine according to the present invention, the internal combustion engine includes first detection means for detecting an air-fuel ratio equivalent value of exhaust flowing into the catalyst, and an air-fuel ratio of exhaust discharged from the catalyst. And a second detecting means for detecting an equivalent value, wherein the control device for the internal combustion engine includes an air-fuel ratio equivalent value of the exhaust gas flowing into the detected catalyst and an empty air exhausted from the detected catalyst. Air-fuel ratio control means for converging the air-fuel ratio inside the catalyst to the target air-fuel ratio based on the fuel-equivalent value is further provided (Section 8).
　この態様によれば、内燃機関に、触媒流入ガスの空燃比相当値を検出可能な第１検出手段と、触媒から排出される排気（以下、適宜「触媒排出ガス」とする）の空燃比相当値を検出可能な第２検出手段とが備わる。尚、「空燃比相当値」とは、その振る舞いが空燃比と一義的な関係を有する値、例えば、空燃比そのものに加えて、酸素濃度等であってもよい。また、これらは、例えば演算式やマップ等を利用した所定の換算処理を経て空燃比に換算可能な電圧値等として検出されてもよい。尚、触媒流入ガスの空燃比及び触媒排出ガスの空燃比とは、好適には、これらのガスの空燃比の時間平均値を意味する。 According to this aspect, in the internal combustion engine, the first detection means capable of detecting the air-fuel ratio equivalent value of the catalyst inflow gas and the air-fuel ratio equivalent of the exhaust gas discharged from the catalyst (hereinafter referred to as “catalyst exhaust gas” as appropriate). Second detection means capable of detecting a value. The “air-fuel ratio equivalent value” may be a value whose behavior has a unique relationship with the air-fuel ratio, such as an oxygen concentration in addition to the air-fuel ratio itself. These may be detected as a voltage value that can be converted into an air-fuel ratio through a predetermined conversion process using, for example, an arithmetic expression or a map. The air-fuel ratio of the catalyst inflow gas and the air-fuel ratio of the catalyst exhaust gas preferably mean time average values of the air-fuel ratio of these gases.
　この態様によれば、空燃比制御手段が、触媒流入ガス及び触媒排出ガスの空燃比相当値に基づいて、触媒内部の空燃比を目標空燃比に収束させる。これ以降、このような空燃比制御手段の制御を適宜「空燃比Ｆ／Ｂ制御」と表現する。空燃比Ｆ／Ｂ制御によれば、触媒内部の空燃比が目標空燃比となるように、各気筒の燃料噴射量が基準となる燃料噴射量から適宜補正されるが、その実践的態様は多義的である。 According to this aspect, the air-fuel ratio control means converges the air-fuel ratio inside the catalyst to the target air-fuel ratio based on the air-fuel ratio equivalent values of the catalyst inflow gas and the catalyst exhaust gas. Hereinafter, such control of the air-fuel ratio control means is appropriately expressed as “air-fuel ratio F / B control”. According to the air-fuel ratio F / B control, the fuel injection amount of each cylinder is appropriately corrected from the reference fuel injection amount so that the air-fuel ratio inside the catalyst becomes the target air-fuel ratio, but its practical aspect is ambiguous. Is.
　例えば、空燃比Ｆ／Ｂは、第２検出手段を利用したサブＦ／Ｂ制御と、第１検出手段を利用したメインＦ／Ｂ制御とから構築されていてもよい。より具体的には、サブＦ／Ｂ制御は、第２検出手段により直接的に又は間接的に検出される空燃比と目標空燃比との偏差に応じて、触媒排出ガスの空燃比を目標空燃比に収束させるためのサブＦ／Ｂ制御量を演算すると共に、このサブＦ／Ｂ制御量に基づいて、第１検出手段により直接的に又は間接的に検出される空燃比又はその目標空燃比を補正する制御として構築されていてもよい。 For example, the air-fuel ratio F / B may be constructed from sub F / B control using the second detection means and main F / B control using the first detection means. More specifically, in the sub F / B control, the air-fuel ratio of the catalyst exhaust gas is set to the target air according to the deviation between the air-fuel ratio detected directly or indirectly by the second detecting means and the target air-fuel ratio. The sub-F / B control amount for converging to the fuel ratio is calculated, and the air-fuel ratio or its target air-fuel ratio detected directly or indirectly by the first detection means based on the sub-F / B control amount It may be constructed as a control for correcting.
　一方、メインＦ／Ｂ制御は、この補正された空燃比と目標空燃比との偏差に応じて、或いは、検出された空燃比とこの補正された目標空燃比との偏差に応じて、触媒流入ガスの空燃比を目標空燃比に収束させるためのメインＦ／Ｂ制御量（例えば、基準噴射量に乗じるべき補正係数等）を決定し、基準噴射量を補正する制御として構築されていてもよい。 On the other hand, in the main F / B control, the catalyst inflow is determined according to the deviation between the corrected air-fuel ratio and the target air-fuel ratio, or according to the deviation between the detected air-fuel ratio and the corrected target air-fuel ratio. The main F / B control amount (for example, a correction coefficient to be multiplied by the reference injection amount) for converging the gas air-fuel ratio to the target air-fuel ratio is determined, and the control may be constructed to correct the reference injection amount. .
　尚、本願における空燃比Ｆ／Ｂ制御は、例えば、Ｆ／Ｂ制御量が比例項（Ｐ項）及び積分項（Ｉ項）を含む所謂ＰＩ制御であってもよいし、Ｆ／Ｂ制御量が比例項及び積分項に更に微分項（Ｄ項）を加えて構築される所謂ＰＩＤ制御であってもよい。また、空燃比Ｆ／Ｂ制御は、全気筒一律になされるものであっても、各気筒個別になされるものであってもよい。 The air-fuel ratio F / B control in the present application may be so-called PI control in which the F / B control amount includes a proportional term (P term) and an integral term (I term), or the F / B control amount, for example. May be so-called PID control constructed by adding a differential term (D term) to the proportional term and the integral term. Further, the air-fuel ratio F / B control may be performed uniformly for all cylinders or may be performed individually for each cylinder.
　このような空燃比Ｆ／Ｂ制御によれば、触媒内部の空燃比を目標空燃比に維持することが出来るため、触媒を硫黄被毒から回復させるべく気筒間の空燃比のインバランス度を変化させるにあたって、機関全体の空燃比に与える影響を軽減することが出来る。従って、排気エミッション及び燃費の悪化を好適に抑制することが出来る。 According to such air-fuel ratio F / B control, the air-fuel ratio inside the catalyst can be maintained at the target air-fuel ratio, so the degree of imbalance of the air-fuel ratio between the cylinders is changed in order to recover the catalyst from sulfur poisoning. In doing so, the influence on the air-fuel ratio of the entire engine can be reduced. Accordingly, it is possible to suitably suppress the deterioration of exhaust emission and fuel consumption.
　本発明に係る内燃機関の制御装置の他の態様では、前記被毒回復制御手段は、燃料噴射装置、吸気弁及び排気弁の少なくとも一方の開閉時期を変化させることが可能な可変動弁装置並びにＥＧＲ装置のうち少なくとも一つを制御する（第９項）。 In another aspect of the control device for an internal combustion engine according to the present invention, the poisoning recovery control means includes a variable valve operating device capable of changing an opening / closing timing of at least one of a fuel injection device, an intake valve, and an exhaust valve, and Control at least one of the EGR devices (Section 9).
　空燃比のインバランスは、気筒内に吸入される空気量と気筒内に供給される燃料量とのバランスが気筒相互間で異なることによって生じるものである。従って、空燃比のインバランス度を制御するにあたっての制御対象として、最も適当なものの一つは、気筒毎に燃料噴射量を変更することが可能な燃料噴射装置である。 The air-fuel ratio imbalance occurs when the balance between the amount of air sucked into the cylinder and the amount of fuel supplied into the cylinder differs between the cylinders. Therefore, one of the most appropriate control targets for controlling the degree of air-fuel ratio imbalance is a fuel injection device capable of changing the fuel injection amount for each cylinder.
　但し、気筒毎に、吸気弁又は排気弁或いはその両方の開閉時期（即ち、端的にはバルブタイミング）や開閉期間（即ち、端的にはバルブリフト量）を異ならしめれば、気筒毎に吸入空気量を変化させることが出来る。従って、気筒において水素を生成させることが出来る。また、気筒毎に独立した吸気絞り弁を有する構成とすれば、同様に気筒毎に吸入空気量を異ならしめることが出来る。 However, if the opening / closing timing of the intake valve and / or the exhaust valve or the opening / closing period (that is, the valve lift amount) is different for each cylinder, the intake air is different for each cylinder. The amount can be changed. Therefore, hydrogen can be generated in the cylinder. Further, if the intake throttle valve is independent for each cylinder, the intake air amount can be made different for each cylinder.
　また、ＥＧＲ（Exhaust Gas Recirculation）装置を介してＥＧＲ率やＥＧＲ量を変化させれば、気筒内部に吸入されるガスに対する新気の割合や形成される混合気の均質性を変化させることが出来る。従って、気筒毎に独立してＥＧＲを導入可能な構成（例えば、各気筒の吸気ポートに夫々ＥＧＲ管とＥＧＲ弁とを備えた構成等）とすれば、気筒毎に吸入空気量を異ならしめることが出来、空燃比のインバランスを実現することが出来る。 Further, if the EGR rate and the EGR amount are changed via an EGR (Exhaust Gas Recirculation) device, the ratio of fresh air to the gas sucked into the cylinder and the homogeneity of the formed air-fuel mixture can be changed. . Therefore, if the configuration is such that EGR can be introduced independently for each cylinder (for example, a configuration in which each cylinder has an EGR pipe and an EGR valve, respectively), the intake air amount can be made different for each cylinder. And an air-fuel ratio imbalance can be realized.
　尚、被毒回復制御手段は、これら空燃比のインバランスを変化させ得る装置に加えて、点火装置を更に制御してもよい。点火時期を遅角側に変化させると、気筒内の燃焼反応の進行が全体的に遅角側に推移する。このため、排気弁が開弁した時点において燃焼反応を継続させておくことが可能となり、排気経路及びそれに連通する触媒の温度上昇を図ることが出来る。触媒床温は上述したように、触媒における水素生成量や触媒における硫黄の脱離に影響する。従って、点火時期の制御を介して、インバランス度による気筒における水素の生成量と、触媒床温とを独立して制御することが可能となる。この場合、触媒床温への影響を配慮することなくインバランス度を制御することが可能となり、インバランス度の制御幅により高い自由度を付与することが出来る。 The poisoning recovery control means may further control the ignition device in addition to the device capable of changing the air-fuel ratio imbalance. When the ignition timing is changed to the retarded angle side, the progress of the combustion reaction in the cylinder generally shifts to the retarded angle side. For this reason, it is possible to continue the combustion reaction when the exhaust valve is opened, and it is possible to increase the temperature of the exhaust path and the catalyst communicating therewith. As described above, the catalyst bed temperature affects the amount of hydrogen produced in the catalyst and the desorption of sulfur in the catalyst. Therefore, it is possible to independently control the amount of hydrogen generated in the cylinder by the imbalance degree and the catalyst bed temperature through the control of the ignition timing. In this case, the imbalance degree can be controlled without considering the influence on the catalyst bed temperature, and a higher degree of freedom can be given by the control range of the imbalance degree.
　本発明に係る内燃機関の制御装置の他の態様では、前記内燃機関は、燃料としてガソリンを使用する内燃機関、燃料として軽油を使用する圧縮自着火式内燃機関、又は、成層燃焼により空燃比がリーン空燃比に維持される燃焼希薄燃焼内燃機関である（第１０項）。 In another aspect of the control device for an internal combustion engine according to the present invention, the internal combustion engine has an internal combustion engine that uses gasoline as a fuel, a compression auto-ignition internal combustion engine that uses light oil as a fuel, or an air-fuel ratio due to stratified combustion. A combustion lean combustion internal combustion engine maintained at a lean air-fuel ratio (Section 10).
　内燃機関の採り得る態様が異なれば、触媒或いは触媒システムの構成も変化するが、例えば三元触媒にせよ、リーンＮＯｘ触媒にせよ、硫黄被毒の問題は同様に生じ得る。その点に鑑みれば、本発明に係る内燃機関の制御装置は、内燃機関の構成によらず適用することが出来る。 If the internal combustion engine can take different forms, the configuration of the catalyst or the catalyst system also changes. However, for example, whether it is a three-way catalyst or a lean NOx catalyst, the problem of sulfur poisoning can also occur. In view of this point, the control device for an internal combustion engine according to the present invention can be applied regardless of the configuration of the internal combustion engine.
　尚、ディーゼルエンジン等の圧縮自着火式内燃機関においては、通常、空燃比制御の概念は存在しないが、燃焼状態の制御により気筒内部で水素を生成することは可能である。 In a compression auto-ignition internal combustion engine such as a diesel engine, there is usually no concept of air-fuel ratio control, but hydrogen can be generated inside the cylinder by controlling the combustion state.
　圧縮自着火式内燃機関は、主として新気が燃料量に対して足りているか否かが問題であり、空燃比制御ではなく噴射量制御により燃焼状態が制御される。逆に言えば、アクセル開度に対して定まる要求噴射量に対して、必要な新気量の下限値が存在する（噴射量の上限ガードに相当する）。この点を利用すれば、例えば、ドライバ要求に応じた燃料噴射量に対して弱酸素不足条件で燃焼を制御すれば、ＣＯ或いはＨＣの生成を惹起することは可能であり、排気経路においてＤＰＦ（Diesel Particulate Filter）等と共に設置されることの多いリーンＮＯｘ触媒の硫黄被毒を好適に解消することが出来る。 Compressed self-ignition internal combustion engines are mainly concerned with whether or not fresh air is sufficient for the amount of fuel, and the combustion state is controlled not by air-fuel ratio control but by injection amount control. In other words, there is a lower limit value of the required fresh air amount for the required injection amount determined with respect to the accelerator opening (corresponding to an upper limit guard for the injection amount). If this point is utilized, for example, if combustion is controlled under weak oxygen deficient conditions with respect to the fuel injection amount according to the driver request, it is possible to cause the generation of CO or HC, and DPF ( The sulfur poisoning of the lean NOx catalyst that is often installed together with Diesel (Particulate Filter) or the like can be suitably eliminated.
　本発明のこのような作用及び他の利得は次に説明する実施形態から明らかにされる。 Such an operation and other advantages of the present invention will be clarified from embodiments described below.
本発明の一実施形態に係るエンジンシステムの構成を概念的に表してなる概略構成図である。1 is a schematic configuration diagram conceptually showing a configuration of an engine system according to an embodiment of the present invention. 図１のエンジンシステムにおいてＥＣＵにより実行される硫黄被毒回復制御のフローチャートである。2 is a flowchart of sulfur poisoning recovery control executed by an ECU in the engine system of FIG. 1. 図４の硫黄被毒回復制御において参照される第１水素濃度マップの概念図である。It is a conceptual diagram of the 1st hydrogen concentration map referred in the sulfur poisoning recovery control of FIG. 図４の硫黄被毒回復制御において参照される第２水素濃度マップの概念図である。It is a conceptual diagram of the 2nd hydrogen concentration map referred in the sulfur poisoning recovery control of FIG. 本発明の第２実施形態に係る硫黄被毒回復制御のフローチャートである。It is a flowchart of the sulfur poisoning recovery control which concerns on 2nd Embodiment of this invention.
　＜発明の実施形態＞
　以下、図面を参照して、本発明の各種実施形態について説明する。 <Embodiment of the Invention>
Hereinafter, various embodiments of the present invention will be described with reference to the drawings.
　＜第１実施形態＞
　＜実施形態の構成＞
　始めに、図１を参照し、本発明の一実施形態に係るエンジンシステム１０の構成について説明する。ここに、図１は、エンジンシステム１０の構成を概念的に表してなる概略構成図である。 <First Embodiment>
<Configuration of Embodiment>
First, the configuration of an engine system 10 according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic configuration diagram conceptually showing the configuration of the engine system 10.
　図１において、エンジンシステム１０は、図示せぬ車両に搭載され、ＥＣＵ１００及びエンジン２００を備える。 1, an engine system 10 is mounted on a vehicle (not shown) and includes an ECU 100 and an engine 200.
　ＥＣＵ１００は、ＣＰＵ、ＲＯＭ及びＲＡＭ等を備え、エンジンシステム１０の動作を制御可能に構成された電子制御ユニットであり、本発明に係る「内燃機関の制御装置」の一例である。ＥＣＵ１００は、ＲＯＭに格納された制御プログラムに従って、後述する硫黄被毒回復制御を実行可能に構成されている。 The ECU 100 is an electronic control unit that includes a CPU, a ROM, a RAM, and the like and is configured to be able to control the operation of the engine system 10, and is an example of the “control device for an internal combustion engine” according to the present invention. The ECU 100 is configured to be able to execute sulfur poisoning recovery control, which will be described later, according to a control program stored in the ROM.
　尚、ＥＣＵ１００は、本発明に係る「判定手段」、「蓄積量推定手段」、「触媒内生成量推定手段」、「筒内生成量推定手段」、「要求量推定手段」、「被毒回復制御手段」及び「空燃比制御手段」の夫々一例として機能し得る一体の電子制御ユニットであるが、本発明に係るこれら各手段の物理的、機械的及び電気的な構成はこれに限定されるものではなく、これら各手段は、例えば複数のＥＣＵ、各種処理ユニット、各種コントローラ或いはマイコン装置等各種コンピュータシステム等として構成されていてもよい。 Note that the ECU 100 includes the “determination unit”, “accumulated amount estimation unit”, “in-catalyst generation amount estimation unit”, “in-cylinder generation amount estimation unit”, “request amount estimation unit”, “poisoning recovery” according to the present invention. It is an integrated electronic control unit that can function as an example of each of “control means” and “air-fuel ratio control means”, but the physical, mechanical, and electrical configurations of these means according to the present invention are limited to this. Instead, these means may be configured as various computer systems such as a plurality of ECUs, various processing units, various controllers, or a microcomputer device.
　エンジン２００は、本発明に係る「内燃機関」の一例たる多気筒ガソリンエンジンである。 Engine 200 is a multi-cylinder gasoline engine that is an example of an “internal combustion engine” according to the present invention.
　図１において、エンジン２００は、シリンダブロックＣＢに収容される複数の気筒２０１を備える。尚、図１において、気筒２０１は紙面奥行き方向に配列しており、図１においては一の気筒２０１のみが示されている。 1, the engine 200 includes a plurality of cylinders 201 accommodated in a cylinder block CB. In FIG. 1, the cylinders 201 are arranged in the depth direction of the drawing, and only one cylinder 201 is shown in FIG. 1.
　エンジン２００において、気筒２０１の内部に形成された燃焼室には、混合気の燃焼に伴う爆発力に応じて図示上下方向に往復運動を生じるピストン２０２を備える。ピストン２０２の往復運動は、コネクティングロッド２０３を介してクランクシャフト２０４の回転運動に変換され、エンジン２００を搭載する車両の動力として利用される構成となっている。 In the engine 200, the combustion chamber formed in the cylinder 201 is provided with a piston 202 that reciprocates in the vertical direction in the figure in accordance with the explosive force accompanying the combustion of the air-fuel mixture. The reciprocating motion of the piston 202 is converted into the rotational motion of the crankshaft 204 via the connecting rod 203 and is used as power for the vehicle on which the engine 200 is mounted.
　クランクシャフト２０４の近傍には、クランクシャフト２０４の回転位置（即ち、クランク角）を検出可能なクランクポジションセンサ２０５が設置されている。このクランクポジションセンサ２０５は、ＥＣＵ１００と電気的に接続されており、検出されたクランク角は、一定又は不定の周期でＥＣＵ１００に参照され、例えば、エンジン回転数ＮＥの算出や、その他の制御に供される構成となっている。 In the vicinity of the crankshaft 204, a crank position sensor 205 capable of detecting the rotational position (ie, crank angle) of the crankshaft 204 is installed. The crank position sensor 205 is electrically connected to the ECU 100, and the detected crank angle is referred to the ECU 100 at a constant or indefinite period. For example, the crank position sensor 205 is used for calculation of the engine speed NE or other control. It becomes the composition which is done.
　エンジン２００において、外部から吸入された空気は、図示せぬクリーナにより浄化された後、各気筒について共通の吸気管２０６に導かれる。吸気管２０６には、この吸入空気の量である吸入空気量を調節可能なスロットルバルブ２０７が配設されている。このスロットルバルブ２０７は、ＥＣＵ１００と電気的に接続された不図示のスロットルバルブモータによってその駆動状態が制御される、一種の電子制御式スロットルバルブとして構成されている。 In the engine 200, air sucked from the outside is purified by a cleaner (not shown) and then guided to a common intake pipe 206 for each cylinder. The intake pipe 206 is provided with a throttle valve 207 that can adjust the amount of intake air that is the amount of intake air. The throttle valve 207 is configured as a kind of electronically controlled throttle valve whose driving state is controlled by a throttle valve motor (not shown) electrically connected to the ECU 100.
　ＥＣＵ１００は、基本的には不図示のアクセルポジションセンサにより検出されるアクセル開度Ｔａに応じたスロットル開度が得られるようにスロットルバルブモータを駆動制御する。但し、ＥＣＵ１００は、スロットルバルブモータの動作制御を介してドライバの意思を介在させることなくスロットル開度を調整することも可能である。 The ECU 100 basically drives and controls the throttle valve motor so as to obtain a throttle opening corresponding to an accelerator opening Ta detected by an unillustrated accelerator position sensor. However, the ECU 100 can also adjust the throttle opening without intervention of the driver's intention through the operation control of the throttle valve motor.
　スロットルバルブ２０７により適宜調量された吸入空気は、気筒２０１の各々に対応する吸気ポート２０８を経由して、吸気弁２０９の開弁時に気筒内部に吸入される。吸気弁２０９は、図示するように断面視略楕円形状を有するカム２１０のカムプロファイルに応じてその開閉時期が規定される構成となっている。 The intake air appropriately adjusted by the throttle valve 207 is sucked into the cylinder through the intake port 208 corresponding to each cylinder 201 when the intake valve 209 is opened. The intake valve 209 is configured such that its opening / closing timing is defined according to the cam profile of a cam 210 having a substantially elliptical shape in cross section as shown in the figure.
　一方、このカム２１０は、例えばカムスプロケットやタイミングチェーン等の動力伝達手段を介してクランクシャフト２０４に連結された吸気カム軸（符号省略）に固定されている。従って、吸気弁２０９の開閉位相は、クランクシャフト２０４の回転位相（即ち、クランク角）と、一の固定状態において一義的な関係にある。 On the other hand, the cam 210 is fixed to an intake camshaft (reference number omitted) connected to the crankshaft 204 via power transmission means such as a cam sprocket or a timing chain. Therefore, the opening / closing phase of the intake valve 209 is uniquely related to the rotation phase of the crankshaft 204 (ie, the crank angle) in one fixed state.
　ここで、この吸気カム２１０と吸気カム軸との固定状態は、油圧駆動装置２１１により供給される制御油の油圧により変化する。より具体的には、吸気カム２１０は、ベーンと呼ばれる翼状部材を介して吸気カム軸に連結されており、このベーンと吸気カム軸との回転位相は、油圧駆動装置２１１が有する油圧室に印加される油圧に応じて変化する構成となっている。従って、ベーンに固定された吸気カム２１０と吸気カム軸との回転位相もまた、当該油圧に応じて変化する。油圧駆動装置２１１は、ＥＣＵ１００と電気的に接続された状態にあり、ＥＣＵ１００は、油圧駆動装置２１１の制御を介して、吸気弁２０９の開閉時期を各気筒独立に変化させることが出来る。即ち、油圧駆動装置２１１は、本発明に係る「可変動弁装置」の採り得る構成の一例である。 Here, the fixed state between the intake cam 210 and the intake camshaft varies depending on the hydraulic pressure of the control oil supplied by the hydraulic drive device 211. More specifically, the intake cam 210 is connected to the intake cam shaft via a wing-like member called a vane, and the rotational phase between the vane and the intake cam shaft is applied to the hydraulic chamber of the hydraulic drive device 211. The configuration changes according to the hydraulic pressure applied. Therefore, the rotational phase between the intake cam 210 fixed to the vane and the intake camshaft also changes according to the hydraulic pressure. The hydraulic drive device 211 is in a state of being electrically connected to the ECU 100, and the ECU 100 can change the opening / closing timing of the intake valve 209 independently for each cylinder through the control of the hydraulic drive device 211. That is, the hydraulic drive device 211 is an example of a configuration that can be adopted by the “variable valve operating device” according to the present invention.
　尚、本発明に係る可変動弁装置の採り得る形態は、本実施形態のものに限定されない。例えば、吸気弁２０９は、ソレノイドアクチュエータ等により電磁的に駆動される、所謂電磁駆動弁（カム・バイワイヤ）であってもよい。 In addition, the form which the variable valve apparatus which concerns on this invention can take is not limited to the thing of this embodiment. For example, the intake valve 209 may be a so-called electromagnetically driven valve (cam-by-wire) that is electromagnetically driven by a solenoid actuator or the like.
　吸気ポート２０８に導かれた吸入空気は、吸気ポート２０８に噴射弁の一部が露出してなる吸気ポートインジェクタ２１２から噴射された燃料（ガソリン）と混合されて前述の混合気となる。燃料たるガソリンは、図示せぬ燃料タンクに貯留されており、図示せぬ低圧フィードポンプの作用により、図示せぬデリバリパイプを介して吸気ポートインジェクタ２１２に供給されている。吸気ポートインジェクタ２１２において、噴射弁を駆動する不図示の駆動装置は、ＥＣＵ１００と電気的に接続されており、吸気ポートインジェクタ２１２は、ＥＣＵ１００がこの駆動装置を介して噴射弁の開弁期間を制御することによって、この開弁期間に応じた量の燃料噴霧を吸気ポート２０８に供給することが出来る。吸気ポートインジェクタ２１２は、本発明に係る「燃料噴射装置」の一例である。 The intake air guided to the intake port 208 is mixed with the fuel (gasoline) injected from the intake port injector 212 in which a part of the injection valve is exposed at the intake port 208 to become the above-described mixture. Gasoline as fuel is stored in a fuel tank (not shown), and is supplied to the intake port injector 212 via a delivery pipe (not shown) by the action of a low-pressure feed pump (not shown). In the intake port injector 212, a drive device (not shown) that drives the injection valve is electrically connected to the ECU 100, and the intake port injector 212 controls the valve opening period of the injection valve via the drive device. By doing so, an amount of fuel spray corresponding to this valve opening period can be supplied to the intake port 208. The intake port injector 212 is an example embodiment that corresponds to the “fuel injection device” according to the present invention.
　エンジン２００の燃焼室には火花点火装置である点火装置２１３の点火プラグ（符号省略）の一部が露出している。エンジン２００の圧縮行程において圧縮された混合気は、この点火プラグの点火動作により着火し燃焼する仕組みとなっている。点火装置２１３は、ＥＣＵ１００と電気的に接続されており、点火装置２１３の点火時期は、ＥＣＵ１００により制御される構成となっている。 In the combustion chamber of the engine 200, a part of a spark plug (not shown) of an ignition device 213 that is a spark ignition device is exposed. The air-fuel mixture compressed in the compression stroke of the engine 200 is ignited and burned by the ignition operation of the spark plug. The ignition device 213 is electrically connected to the ECU 100, and the ignition timing of the ignition device 213 is controlled by the ECU 100.
　一方、燃焼室において燃焼反応を生じた混合気は、燃焼行程に引き続く排気行程において、クランクシャフト２０４と間接的に連結された排気カム２１４のカムプロファイルにより開閉駆動される排気弁２１５の開弁時に、排気ポート２１６に排出される。 On the other hand, the air-fuel mixture that has undergone a combustion reaction in the combustion chamber is opened and closed by an exhaust valve 215 that is driven to open and close by the cam profile of the exhaust cam 214 that is indirectly connected to the crankshaft 204 in the exhaust stroke following the combustion stroke. The exhaust port 216 is discharged.
　この排気ポート２１６は、その下流側（気筒２０１から遠ざかる側）において排気マニホールド（断面視の形態を採る関係上、図１では示されていない）に接続される。排気マニホールドは、排気ポート２１６から排出される排気を、全気筒について集約した後に排気管２１９に導く装置であり、排気管２１９に繋がっている。 The exhaust port 216 is connected to an exhaust manifold (not shown in FIG. 1 because of its cross-sectional view) on the downstream side (side away from the cylinder 201). The exhaust manifold is a device that guides the exhaust discharged from the exhaust port 216 to the exhaust pipe 219 after collecting all the cylinders, and is connected to the exhaust pipe 219.
　排気ポート２１６に繋がる上記排気マニホールドには、ＥＧＲ管２１７の一端部が連結されている。ＥＧＲ管２１７は、吸気ポート２０８の上流側に位置する吸気マニホールド（符号省略）にその他端部が連結されており、排気の一部をＥＧＲガスとして吸気系に戻すことが出来る。 One end of an EGR pipe 217 is connected to the exhaust manifold connected to the exhaust port 216. The other end of the EGR pipe 217 is connected to an intake manifold (reference numeral omitted) located on the upstream side of the intake port 208, and a part of the exhaust can be returned to the intake system as EGR gas.
　ＥＧＲガスの供給量たるＥＧＲ量は、ＥＧＲ管２１７に設置されたＥＧＲ弁２１８により制御される。ＥＧＲ弁２１８は、ソレノイドの電磁力により弁の開閉を制御する電磁駆動弁であり、当該ソレノイドの励磁状態を制御する駆動装置と電気的に接続されたＥＣＵ１００の制御により、その弁開度が制御される構成となっている。 The EGR amount that is the supply amount of EGR gas is controlled by an EGR valve 218 installed in the EGR pipe 217. The EGR valve 218 is an electromagnetically driven valve that controls the opening and closing of the valve by the electromagnetic force of the solenoid, and the valve opening degree is controlled by the control of the ECU 100 electrically connected to the drive device that controls the excitation state of the solenoid. It becomes the composition which is done.
　尚、図１では、ＥＧＲ管２１７が排気ポート２１６に繋がる排気マニホールドに連結されるものとしたが、ＥＧＲ管２１７は、この排気マニホールドに繋がる排気管２１９に連結されていてもよい。 In FIG. 1, the EGR pipe 217 is connected to the exhaust manifold connected to the exhaust port 216. However, the EGR pipe 217 may be connected to the exhaust pipe 219 connected to the exhaust manifold.
　本実施形態においては、ＥＧＲ管２１７が、後述する三元触媒２２０よりも上流側（気筒側）において排気系に接続されており、ＥＧＲ管２１７とＥＧＲ弁２１８とにより、本発明に係る「ＥＧＲ装置」の一例たるＨＰＬ（High Pressure Loop）ＥＧＲ装置が構成される。しかしながら、ＥＧＲ装置の構成はこれに限定されない。例えば、ＥＧＲ装置は、ＥＧＲ管２１７が排気管２１９における後述する三元触媒２２０の下流側に連結され、三元触媒通過後の排気を取り出すＬＰＬ（Low Pressure Loop）ＥＧＲ装置であってもよい。 In the present embodiment, the EGR pipe 217 is connected to the exhaust system on the upstream side (cylinder side) from the three-way catalyst 220 described later, and the EGR pipe 217 and the EGR valve 218 provide the “EGR” according to the present invention. An HPL (High Pressure Loop) EGR device, which is an example of the “device”, is configured. However, the configuration of the EGR device is not limited to this. For example, the EGR device may be an LPL (Low Pressure-Loop) EGR device in which the EGR pipe 217 is connected to the downstream side of a three-way catalyst 220 described later in the exhaust pipe 219 and takes out exhaust gas after passing through the three-way catalyst.
　各気筒の排気ポート２１６には、排気管２１９が連結されている。排気管２１４は、本発明に係る「排気経路」の一例である。 The exhaust pipe 219 is connected to the exhaust port 216 of each cylinder. The exhaust pipe 214 is an example of an “exhaust path” according to the present invention.
　排気管２１９には、本発明に係る「排気浄化用の触媒」の一例たる三元触媒２２０が設置される。三元触媒２１５は、触媒担体に白金等の貴金属が担持された公知の触媒装置であり、ＨＣ及びＣＯの酸化燃焼反応と、窒素酸化物ＮＯｘの還元反応とを略同時に進行させることによって排気を浄化可能に構成される。尚、三元触媒２２０が上記排気マニホールドに接続された排気管２１９に設置されるところ、本実施形態において三元触媒２２０に流入する排気は、エンジン２００の全気筒について集約された後の排気である。 The exhaust pipe 219 is provided with a three-way catalyst 220 as an example of the “exhaust purification catalyst” according to the present invention. The three-way catalyst 215 is a known catalyst device in which a noble metal such as platinum is supported on a catalyst carrier. The three-way catalyst 215 emits exhaust gas by causing the oxidative combustion reaction of HC and CO and the reduction reaction of nitrogen oxide NOx to proceed substantially simultaneously. It can be purified. Note that when the three-way catalyst 220 is installed in the exhaust pipe 219 connected to the exhaust manifold, the exhaust gas flowing into the three-way catalyst 220 in this embodiment is the exhaust after being aggregated for all the cylinders of the engine 200. is there.
　排気管２１９における三元触媒２２０の上流側には、三元触媒２２０に流入する触媒流入ガス（全気筒について集約された後の排気）の空燃比である入力側空燃比Ａ／Ｆｉｎを検出可能な空燃比センサ２２１が設置されている。空燃比センサ２２１は、例えば、拡散抵抗層を備えた限界電流式広域空燃比センサであり、本発明に係る「第１検出手段」の一例である。 On the upstream side of the three-way catalyst 220 in the exhaust pipe 219, the input side air-fuel ratio A / Fin that is the air-fuel ratio of the catalyst inflow gas (exhaust after being aggregated for all cylinders) flowing into the three-way catalyst 220 can be detected. An air-fuel ratio sensor 221 is installed. The air-fuel ratio sensor 221 is, for example, a limiting current type wide-area air-fuel ratio sensor provided with a diffusion resistance layer, and is an example of the “first detection means” according to the present invention.
　空燃比センサ２２１は、三元触媒２２０上流側の排気（即ち、触媒流入ガス）の空燃比である入力側空燃比Ａ／Ｆｉｎに応じた出力電圧値Ｖａｆｉｎ（即ち、本発明に係る「空燃比相当値」の一例）を出力するセンサである。即ち、空燃比センサ２２１は、入力側空燃比Ａ／Ｆｉｎと一義的な関係を有する電圧値により間接的に入力側空燃比Ａ／Ｆｉｎを検出する構成を採る。 The air-fuel ratio sensor 221 outputs the output voltage value Vafin (that is, the “air-fuel ratio according to the present invention” corresponding to the input-side air-fuel ratio A / Fin that is the air-fuel ratio of the exhaust (that is, catalyst inflow gas) upstream of the three-way catalyst 220. This is a sensor that outputs an example of “equivalent value”. That is, the air-fuel ratio sensor 221 employs a configuration in which the input-side air-fuel ratio A / Fin is indirectly detected by a voltage value having a unique relationship with the input-side air-fuel ratio A / Fin.
　この出力電圧値Ｖａｆｉｎは、入力側空燃比Ａ／Ｆｉｎが理論空燃比である時に基準出力電圧値Ｖｓｔに一致する。また、この出力電圧値Ｖａｆｉｎは、入力側空燃比Ａ／Ｆｉｎが空燃比リッチ側にある場合に基準出力電圧値Ｖｓｔより低くなり、入力側空燃比Ａ／Ｆｉｎが空燃比リーン側にある場合に基準出力電圧値Ｖｓｔより高くなる。即ち、出力電圧値Ｖａｆｉｎは、入力側空燃比Ａ／Ｆｉｎの変化に対して連続的に変化する。空燃比センサ２２１は、ＥＣＵ１００と電気的に接続されており、検出された出力電圧値Ｖａｆｉｎは、ＥＣＵ１００により一定又は不定の周期で参照される構成となっている。 The output voltage value Vafin matches the reference output voltage value Vst when the input side air-fuel ratio A / Fin is the stoichiometric air-fuel ratio. The output voltage value Vafin is lower than the reference output voltage value Vst when the input side air-fuel ratio A / Fin is on the air-fuel ratio rich side, and when the input-side air-fuel ratio A / Fin is on the air-fuel ratio lean side. It becomes higher than the reference output voltage value Vst. That is, the output voltage value Vafin continuously changes with respect to the change of the input side air-fuel ratio A / Fin. The air-fuel ratio sensor 221 is electrically connected to the ECU 100, and the detected output voltage value Vafin is referred to by the ECU 100 at a constant or indefinite period.
　排気管２１９における三元触媒２２０の下流側には、三元触媒２２０を通過した触媒排出ガスの酸素濃度である下流側酸素濃度Ｃｏｘｓを検出可能なＯ２センサ２２２が設置されている。Ｏ２センサ２２２は、周知の起電力式酸素濃度センサ（即ち、安定化ジルコニアを用いた濃淡電池型の酸素濃度センサ）であり、本発明に係る「第２検出手段」の一例である。 On the downstream side of the three-way catalyst 220 in the exhaust pipe 219, an O 2 sensor 222 that can detect the downstream oxygen concentration Coxs that is the oxygen concentration of the catalyst exhaust gas that has passed through the three-way catalyst 220 is installed. The O 2 sensor 222 is a known electromotive force type oxygen concentration sensor (that is, a concentration cell type oxygen concentration sensor using stabilized zirconia), and is an example of the “second detection means” according to the present invention.
　Ｏ２センサ２２２は、下流側酸素濃度Ｃｏｘｓに応じた出力電圧値Ｖｏｘｓ（即ち、本発明に係る「空燃比相当値」の一例）を出力するセンサである。即ち、Ｏ２センサ２２２は、酸素濃度と一義的な関係を有する電圧値により間接的に酸素濃度を検出する構成を採る。 The O 2 sensor 222 is a sensor that outputs an output voltage value Voxs (that is, an example of an “air-fuel ratio equivalent value” according to the present invention) corresponding to the downstream oxygen concentration Coxs. That is, the O 2 sensor 222 adopts a configuration in which the oxygen concentration is indirectly detected by a voltage value having a unique relationship with the oxygen concentration.
　Ｏ２センサ２２２の出力電圧値Ｖｏｘｓは、触媒排出ガスの空燃比が理論空燃比である場合（言い換えれば、下流側酸素濃度Ｃｏｘｓが理論空燃比に相当する基準酸素濃度Ｃｏｘｓｂである場合）に基準出力電圧値Ｖｏｘｓｂ（例えば、約０．５Ｖ程度）に一致する。また、出力電圧値Ｖｏｘｓは、触媒排出ガスの空燃比が理論空燃比に対し空燃比リッチ側にある場合に基準出力電圧値Ｖｏｘｓｂよりも高くなり、同じく空燃比が空燃比リーン側にある場合に基準出力電圧値Ｖｏｘｓｂよりも低くなる。 The output voltage value Voxs of the O 2 sensor 222 is a reference when the air-fuel ratio of the catalyst exhaust gas is the stoichiometric air-fuel ratio (in other words, when the downstream oxygen concentration Coxs is the reference oxygen concentration Coxsb corresponding to the stoichiometric air-fuel ratio). It corresponds to the output voltage value Voxsb (for example, about 0.5V). The output voltage value Voxs is higher than the reference output voltage value Voxsb when the air-fuel ratio of the catalyst exhaust gas is on the air-fuel ratio rich side with respect to the stoichiometric air-fuel ratio, and when the air-fuel ratio is also on the air-fuel ratio lean side. It becomes lower than the reference output voltage value Voxsb.
　具体的には、触媒排出ガスの空燃比が、理論空燃比とリッチ側検出限界空燃比との間にある場合、Ｏ２センサ２２２の出力電圧値Ｖｏｘｓは、空燃比の減少（即ち、酸素濃度Ｃｏｘｓの減少）に伴って、係るリッチ側検出限界空燃比に相当する最大出力電圧値Ｖｏｘｓｍａｘ（例えば、約０．９Ｖ程度）まで比較的急峻に、略線形に増加する。リッチ側検出限界空燃比よりもリッチ側の空燃比領域において、出力電圧値Ｖｏｘｓは最大出力電圧値Ｖｏｘｓｍａｘで略一定となる。 Specifically, when the air-fuel ratio of the catalyst exhaust gas is between the stoichiometric air-fuel ratio and the rich detection limit air-fuel ratio, the output voltage value Voxs of the O 2 sensor 222 is a decrease in the air-fuel ratio (ie, oxygen concentration). With a decrease in Coxs), it increases relatively linearly and substantially linearly to a maximum output voltage value Voxsmax (for example, about 0.9 V) corresponding to the rich-side detection limit air-fuel ratio. In the air-fuel ratio region on the rich side with respect to the rich-side detection limit air-fuel ratio, the output voltage value Voxs is substantially constant at the maximum output voltage value Voxsmax.
　また、触媒排出ガスの空燃比が、理論空燃比とリーン側検出限界空燃比との間にある場合、Ｏ２センサ２２２の出力電圧値Ｖｏｘｓは、空燃比の増加（即ち、酸素濃度Ｃｏｘｓの増加）に伴って、係るリーン側検出限界空燃比に相当する最小出力電圧値Ｖｏｘｓｍｉｎ（例えば、約０．１Ｖ程度）まで比較的急峻に、略線形に減少する。リーン側検出限界空燃比よりもリーン側の空燃比領域において、出力電圧値Ｖｏｘｓは最小出力電圧値Ｖｏｘｓｍｉｎで略一定となる。 When the air-fuel ratio of the catalyst exhaust gas is between the stoichiometric air-fuel ratio and the lean side detection limit air-fuel ratio, the output voltage value Voxs of the O 2 sensor 222 increases the air-fuel ratio (that is, the oxygen concentration Coxs increases). ) To a minimum output voltage value Voxsmin (for example, about 0.1 V) corresponding to the lean-side detection limit air-fuel ratio, it decreases relatively linearly and substantially linearly. In the air-fuel ratio region leaner than the lean-side detection limit air-fuel ratio, the output voltage value Voxs is substantially constant at the minimum output voltage value Voxsmin.
　Ｏ２センサ２２２は、ＥＣＵ１００と電気的に接続されており、検出された出力電圧値Ｖｏｘｓは、ＥＣＵ１００により一定又は不定の周期で参照される構成となっている。 The O 2 sensor 222 is electrically connected to the ECU 100, and the detected output voltage value Voxs is referred to by the ECU 100 at a constant or indefinite period.
　エンジン２００において、シリンダブロックＣＢを取り囲むように設置されたウォータジャケットには、エンジン２００を冷却するために循環供給される冷却水（ＬＬＣ）の温度である冷却水温Ｔｗを検出可能な水温センサ２２３が配設されている。水温センサ２２３は、ＥＣＵ１００と電気的に接続されており、検出された冷却水温Ｔｗは、ＥＣＵ１００により一定又は不定の周期で参照される構成となっている。 In the engine 200, a water temperature sensor 223 capable of detecting a cooling water temperature Tw, which is a temperature of cooling water (LLC) circulated and supplied to cool the engine 200, is installed in a water jacket installed so as to surround the cylinder block CB. It is arranged. The water temperature sensor 223 is electrically connected to the ECU 100, and the detected cooling water temperature Tw is referred to by the ECU 100 at a constant or indefinite period.
　また、エンジン２００において、吸気管２０６には、吸入空気量Ｇａを検出可能なエアフローメータ２２４が配設されている。エアフローメータ２２４は、ＥＣＵ１００と電気的に接続されており、検出された吸入空気量Ｇａは、ＥＣＵ１００により一定又は不定の周期で参照される構成となっている。 Further, in the engine 200, the intake pipe 206 is provided with an air flow meter 224 capable of detecting the intake air amount Ga. The air flow meter 224 is electrically connected to the ECU 100, and the detected intake air amount Ga is referred to by the ECU 100 at a constant or indefinite period.
　尚、本実施形態に係るエンジン２００は、ガソリンを燃料とする無過給エンジンであるが、本発明に係る内燃機関の構成は、エンジン２００に限定されず多様であってよい。例えば、本発明に係る内燃機関は、気筒数、気筒配列、燃料種別、燃料の噴射態様、吸排気系の構成、動弁系の構成、燃焼方式、過給器の有無及び過給態様等が、エンジン２００と異なっていてもよい。 The engine 200 according to the present embodiment is a non-supercharged engine using gasoline as a fuel, but the configuration of the internal combustion engine according to the present invention is not limited to the engine 200 and may be various. For example, the internal combustion engine according to the present invention has the number of cylinders, cylinder arrangement, fuel type, fuel injection mode, intake / exhaust system configuration, valve operating system configuration, combustion system, presence / absence of supercharger, supercharging mode, etc. The engine 200 may be different.
　例えば、エンジンシステム１０は、エンジン２００に替えて、圧縮自着火式内燃機関であるディーゼルエンジンを備えていてもよいし、吸気ポートインジェクタ２１２に替えて又は加えて気筒内部に燃料を噴射可能な直噴インジェクタを備えた直噴エンジンを備えていてもよい。直噴エンジンである場合、エンジン２００のように均質燃焼の代わりに成層燃焼による空燃比リーン側でのリーンバーン（希薄燃焼）が行われてもよい。また、各エンジン構成において、吸気系に過給器が設置されていてもよい。この場合、過給器のコンプレッサは、排気タービンにより駆動される構成であってもよいし、機関トルクにより機械的に駆動される構成であってもよい。 For example, the engine system 10 may include a diesel engine that is a compression self-ignition internal combustion engine instead of the engine 200, or a direct injection capable of injecting fuel into the cylinder instead of or in addition to the intake port injector 212. You may provide the direct-injection engine provided with the injection injector. In the case of a direct injection engine, lean burn (lean combustion) may be performed on the lean side of the air-fuel ratio by stratified combustion instead of homogeneous combustion as in the engine 200. In each engine configuration, a supercharger may be installed in the intake system. In this case, the compressor of the supercharger may be configured to be driven by an exhaust turbine, or may be configured to be mechanically driven by engine torque.
　エンジンの態様が異なれば、排気系における触媒システムの構築態様も異なり得るが、いずれの構成においても、後述する硫黄被毒回復制御の概念は適用可能である。 Although the construction mode of the catalyst system in the exhaust system may be different if the engine mode is different, the concept of sulfur poisoning recovery control described later can be applied to any configuration.
　＜実施形態の動作＞
　＜空燃比Ｆ／Ｂ制御の概要＞
　エンジン２００において、吸気ポートインジェクタ２１２の燃料噴射量Ｑｐｆｉは、ＥＣＵ１００により、エンジン２００の稼動期間について常時実行される空燃比Ｆ／Ｂ制御により制御される。 <Operation of Embodiment>
<Outline of air-fuel ratio F / B control>
In engine 200, fuel injection amount Qpfi of intake port injector 212 is controlled by ECU 100 by air-fuel ratio F / B control that is always executed during the operation period of engine 200.
　本実施形態に係る空燃比Ｆ／Ｂ制御は、メインＦ／Ｂ制御とサブＦ／Ｂ制御とから構成される。 The air-fuel ratio F / B control according to the present embodiment includes a main F / B control and a sub F / B control.
　メインＦ／Ｂ制御は、空燃比センサ２２１の出力電圧値Ｖａｆｉｎに基づいて得られる入力側空燃比Ａ／Ｆｉｎが入力側目標空燃比Ａ／Ｆｉｎｔｇに収束するようになされる燃料噴射量の制御である。 The main F / B control is control of the fuel injection amount so that the input side air-fuel ratio A / Fin obtained based on the output voltage value Vafin of the air-fuel ratio sensor 221 converges to the input side target air-fuel ratio A / Fintg. is there.
　サブＦ／Ｂ制御は、Ｏ２センサ２２２の出力電圧値Ｖｏｘｓが目標出力電圧値Ｖｏｘｓｔｇに収束するように空燃比センサ２２１の出力電圧値Ｖａｆｉｎ又は入力側目標空燃比Ａ／Ｆｉｎｔｇを補正する制御である。 The sub F / B control is a control for correcting the output voltage value Vafin of the air-fuel ratio sensor 221 or the input side target air-fuel ratio A / Fintg so that the output voltage value Voxs of the O 2 sensor 222 converges to the target output voltage value Voxstg. is there.
　メインＦ／Ｂ制御及びサブＦ／Ｂ制御を含む空燃比Ｆ／Ｂ制御が実行されると、三元触媒２２０の内部の空燃比を目標空燃比に収束させることが出来る。目標空燃比とは、三元触媒２２０の排気浄化作用が最適化される空燃比であって、例えば、理論空燃比である。無論、この目標空燃比は、エミッションや燃費を勘案して許容される範囲で、エンジン２００の要求性能等に応じて適宜変更されてもよく、また実際に適宜変更される。 When the air-fuel ratio F / B control including the main F / B control and the sub F / B control is executed, the air-fuel ratio inside the three-way catalyst 220 can be converged to the target air-fuel ratio. The target air-fuel ratio is an air-fuel ratio that optimizes the exhaust purification action of the three-way catalyst 220, and is, for example, a theoretical air-fuel ratio. Of course, this target air-fuel ratio may be changed as appropriate according to the required performance of the engine 200, etc., as long as it is allowed in consideration of emissions and fuel consumption, and may be changed as appropriate.
　メインＦ／Ｂ制御及びサブＦ／Ｂ制御を実行するにあたって、ＥＣＵ１００は、本発明における「空燃比制御手段」の一例として機能する。尚、このような触媒上下流の空燃比相当値に基づいたフィードバック制御は、従来各種のものが提案されており、ここでは、説明の煩雑化を防ぐ目的からこれ以上の詳細については割愛する。 In executing the main F / B control and the sub F / B control, the ECU 100 functions as an example of the “air-fuel ratio control means” in the present invention. Various feedback controls based on the values corresponding to the air / fuel ratio upstream and downstream of the catalyst have been proposed in the past, and further details are omitted here for the purpose of preventing complication of explanation.
　＜硫黄被毒回復制御の詳細＞
　エンジン２００に使用されるガソリンには、多寡はあれ硫黄が含まれることが多い。この燃料中の硫黄は、気筒２０１内部において、或いは排気管２１９において、酸素と結びついて硫黄酸化物（ＳＯｘ）となり易い。硫黄酸化物は、三元触媒２２０の貴金属と化学的に結び付き易く、エンジン２００の稼動期間において、三元触媒２２０は徐々に硫黄被毒する。エンジンシステム１０では、この三元触媒２２０を硫黄被毒から回復させるために、ＥＣＵ１００により、硫黄被毒回復制御が実行される。ここで、図２を参照し、硫黄被毒回復制御の詳細について説明する。ここに、図２は、硫黄被毒回復制御のフローチャートである。尚、硫黄被毒回復制御は、ＥＣＵ１００が、上述した空燃比Ｆ／Ｂ制御の一サブルーチンとして実行するものとする。 <Details of sulfur poisoning recovery control>
The gasoline used for the engine 200 often contains sulfur. The sulfur in the fuel is likely to be combined with oxygen in the cylinder 201 or in the exhaust pipe 219 to become sulfur oxide (SOx). The sulfur oxide is easily chemically combined with the noble metal of the three-way catalyst 220, and the three-way catalyst 220 is gradually poisoned with sulfur during the operation period of the engine 200. In the engine system 10, the sulfur poisoning recovery control is executed by the ECU 100 in order to recover the three-way catalyst 220 from the sulfur poisoning. Here, with reference to FIG. 2, the detail of sulfur poisoning recovery | restoration control is demonstrated. FIG. 2 is a flowchart of the sulfur poisoning recovery control. Note that the sulfur poisoning recovery control is executed by the ECU 100 as a subroutine of the air-fuel ratio F / B control described above.
　図２において、ＥＣＵ１００は、三元触媒２２０の硫黄蓄積量Ａｓｆを取得する（ステップＳ１０１）。硫黄蓄積量Ａｓｆとは、前回の硫黄被毒回復制御が終了してから現在に至る期間において、三元触媒２２０に蓄積された硫黄の量であり、本発明に係る「触媒における硫黄の蓄積量」の一例である。硫黄蓄積量Ａｓｆは、ＥＣＵ１００が、硫黄被毒回復制御とは別の制御ルーチンで繰り返し演算しており、ＲＡＭ等の書き換え可能なメモリに適宜更新を伴いつつ記憶している。即ち、硫黄蓄積量Ｄｓｆを演算する過程において、ＥＣＵ１００は、本発明に係る「蓄積量推定手段」の一例として機能する。 2, the ECU 100 acquires the sulfur accumulation amount Asf of the three-way catalyst 220 (step S101). The sulfur accumulation amount Asf is the amount of sulfur accumulated in the three-way catalyst 220 during the period from the end of the previous sulfur poisoning recovery control to the present. Is an example. The sulfur accumulation amount Asf is repeatedly calculated by the ECU 100 in a control routine different from the sulfur poisoning recovery control, and is stored in a rewritable memory such as a RAM with appropriate updating. That is, in the process of calculating the sulfur accumulation amount Dsf, the ECU 100 functions as an example of “accumulation amount estimation means” according to the present invention.
　ＥＣＵ１００は、燃料噴射量Ｑｐｆｉを各気筒各サイクルについて積算した値である積算燃料消費量ΣＱｐｆｉから硫黄蓄積量Ｄｓｆを推定する。尚、予め単位燃料中の硫黄含有量は初期値として与えられているものとする。ＥＣＵ１００は、その時点の積算燃料消費量ΣＱｐｆｉに対し、所定の蓄積率σを乗じることによって硫黄蓄積量Ｄｓｆを算出する。蓄積率σは、排気管２１９に排出された硫黄のうち三元触媒２２０に蓄積する硫黄の比率を表す補正係数であり、予め実験的に、経験的に又は理論的に、機関回転数ＮＥ及び負荷率ＫＬ（即ち、気筒２０１に吸入された新気量の物理的最大値に対する割合である）をパラメータとして制御マップに格納されている。定性的には、機関回転数ＮＥが高い程、また、負荷率ＫＬが大きい程、蓄積率σは弱減少傾向となる。尚、このような硫黄蓄積量Ｄｓｆの推定態様は、一例であり、硫黄蓄積量の算出には公知の各種態様を適用可能である。 The ECU 100 estimates the sulfur accumulation amount Dsf from the accumulated fuel consumption amount ΣQpfi that is a value obtained by accumulating the fuel injection amount Qpfi for each cycle of each cylinder. It is assumed that the sulfur content in the unit fuel is given as an initial value in advance. The ECU 100 calculates the sulfur accumulation amount Dsf by multiplying the accumulated fuel consumption amount ΣQpfi at that time by a predetermined accumulation rate σ. The accumulation rate σ is a correction coefficient that represents the ratio of sulfur accumulated in the three-way catalyst 220 among the sulfur discharged to the exhaust pipe 219, and is experimentally, empirically, or theoretically preliminarily experimentally and empirically or theoretically. The load factor KL (that is, the ratio of the fresh air amount taken into the cylinder 201 with respect to the physical maximum value) is stored in the control map as a parameter. Qualitatively, the higher the engine speed NE and the greater the load factor KL, the weaker the accumulation rate σ tends to decrease. Note that such an estimation mode of the sulfur accumulation amount Dsf is an example, and various known modes can be applied to the calculation of the sulfur accumulation amount.
　次に、ＥＣＵ１００は、触媒内水素生成量Ａｈ２ｃａｔを取得する（ステップＳ１０２）。 Next, the ECU 100 acquires the in-catalyst hydrogen generation amount Ah2cat (step S102).
　触媒内水素生成量Ａｈ２ｃａｔとは、前回の硫黄被毒回復制御が終了してから現在に至る期間において、三元触媒２２０で生成された水素の積算量であり、本発明に係る「触媒における水素の生成量」の一例である。触媒内水素生成量Ａｈ２ｃａｔは、ＥＣＵ１００が、硫黄被毒回復制御とは別の制御ルーチンで繰り返し演算しており、ＲＡＭ等の書き換え可能なメモリに適宜更新を伴いつつ記憶している。即ち、触媒内水素生成量Ａｈ２ｃａｔを演算する過程において、ＥＣＵ１００は、本発明に係る「触媒内生成量推定手段」の一例として機能する。 The in-catalyst hydrogen production amount Ah2cat is an integrated amount of hydrogen produced by the three-way catalyst 220 in the period from the end of the previous sulfur poisoning recovery control to the present, Is an example. The in-catalyst hydrogen generation amount Ah2cat is repeatedly calculated by the ECU 100 in a control routine different from the sulfur poisoning recovery control, and stored in a rewritable memory such as a RAM with appropriate updating. That is, in the process of calculating the in-catalyst hydrogen generation amount Ah2cat, the ECU 100 functions as an example of the “in-catalyst generation amount estimation means” according to the present invention.
　ＥＣＵ１００は、触媒内水素生成量Ａｈ２ｃａｔを、三元触媒２２０の触媒床温Ｔｃａｔに基づいて取得する。より具体的には、ＥＣＵ１００のＲＯＭには、触媒床温Ｔｃａｔと水素濃度との関係を規定する第１水素濃度マップが格納されており、ＥＣＵ１００は、第１水素濃度マップから、触媒床温Ｔｃａｔに該当する水素濃度を推定し、推定された水素濃度から触媒内水素生成量Ａｈ２ｃａｔを算出する構成となっている。 ECU100 acquires in-catalyst hydrogen production amount Ah2cat based on catalyst bed temperature Tcat of the three-way catalyst 220. More specifically, the ROM of the ECU 100 stores a first hydrogen concentration map that defines the relationship between the catalyst bed temperature Tcat and the hydrogen concentration, and the ECU 100 reads the catalyst bed temperature Tcat from the first hydrogen concentration map. The hydrogen concentration corresponding to is estimated, and the in-catalyst hydrogen generation amount Ah2cat is calculated from the estimated hydrogen concentration.
　触媒床温Ｔｃａｔは、最新のＩＧオンタイミング以降、硫黄被毒回復制御とは別の制御ルーチンにおいて、当該タイミング以降の積算燃料消費量（先のΣＱｐｆｉと概念的には同様である）に基づいて推定される。具体的には、積算燃料消費量と触媒床温Ｔｃａｔとの関係を表す制御マップが予めＲＯＭに格納されており、ＥＣＵ１００は、当該制御マップから、積算燃料消費量に対応する温度値を取得することによって触媒床温Ｔｃａｔを推定する。尚、三元触媒２２０に温度センサが配置される場合には、当該温度センサの検出値が使用されてもよい。 The catalyst bed temperature Tcat is based on the accumulated fuel consumption (conceptually similar to the previous ΣQpfi) after the latest IG ON timing in a control routine different from the sulfur poisoning recovery control. Presumed. Specifically, a control map representing the relationship between the accumulated fuel consumption and the catalyst bed temperature Tcat is stored in advance in the ROM, and the ECU 100 acquires a temperature value corresponding to the accumulated fuel consumption from the control map. As a result, the catalyst bed temperature Tcat is estimated. In addition, when a temperature sensor is arrange | positioned at the three-way catalyst 220, the detected value of the said temperature sensor may be used.
　ここで、図３を参照し、第１水素濃度マップの詳細について説明する。ここに、図３は、第１水素濃度マップの概念図である。 Here, the details of the first hydrogen concentration map will be described with reference to FIG. FIG. 3 is a conceptual diagram of the first hydrogen concentration map.
　図３において、縦軸及び横軸には夫々三元触媒２２０における水素濃度及び触媒床温Ｔｃａｔが表される。 3, the vertical axis and the horizontal axis represent the hydrogen concentration and the catalyst bed temperature Tcat in the three-way catalyst 220, respectively.
　図示するように、三元触媒２２０においては、概ね６００℃付近前後の温度領域に位置する水素欠乏領域（ハッチング領域）を境に、低温側及び高温側の双方で相応の水素が発生する。水素欠乏領域よりも低温側においては主として水性ガスシフト反応により水素が発生し、同じく高温側においては主として水蒸気改質反応により水素が発生する。 As shown in the figure, in the three-way catalyst 220, corresponding hydrogen is generated on both the low temperature side and the high temperature side, with a hydrogen deficient region (hatched region) located in the temperature region around 600 ° C. being the boundary. On the low temperature side of the hydrogen-deficient region, hydrogen is generated mainly by the water gas shift reaction, and on the high temperature side, hydrogen is generated mainly by the steam reforming reaction.
　第１水素濃度マップには、図３に例示される、水性ガスシフト反応及び水蒸気改質反応を定量的に解析した結果として得られる触媒床温Ｔｃａｔと水素濃度との関係が予め数値化されて格納されている。ここで、水素量でなく水素濃度であるのは、水素量が、三元触媒２２０に流入する触媒流入ガスの総量に依存するからである。即ち、ＥＣＵ１００は、第１水素濃度マップから取得される水素濃度と、機関回転数ＮＥ及び負荷率ＫＬに基づいて、単位時間における、三元触媒２２０における水素の生成量を推定する。この推定された単位時間当たりの水素の生成量は随時積算され、その積算値がＲＡＭ等の記憶手段に一時的に記憶されている。触媒内水素生成量Ａｈ２ｃａｔとは、この記憶された積算値である。 In the first hydrogen concentration map, the relationship between the catalyst bed temperature Tcat and the hydrogen concentration obtained as a result of quantitative analysis of the water gas shift reaction and the steam reforming reaction illustrated in FIG. Has been. Here, the hydrogen concentration, not the hydrogen amount, is because the hydrogen amount depends on the total amount of the catalyst inflow gas flowing into the three-way catalyst 220. That is, the ECU 100 estimates the amount of hydrogen generated in the three-way catalyst 220 per unit time based on the hydrogen concentration acquired from the first hydrogen concentration map, the engine speed NE, and the load factor KL. The estimated amount of hydrogen generated per unit time is accumulated as needed, and the accumulated value is temporarily stored in a storage means such as a RAM. The in-catalyst hydrogen production amount Ah2cat is the stored integrated value.
　図２に戻り、ＥＣＵ１００は、ステップＳ１０１で取得された硫黄蓄積量Ａｓｆと、ステップＳ１０２で取得された触媒内水素生成量Ａｈ２ｃａｔとに基づいて、補正後蓄積量Ａｓｆｃｏｒを算出する（ステップＳ１０３）。補正後蓄積量Ａｓｆｃｏｒは、三元触媒２２０に蓄積された硫黄のうち、三元触媒２２０で生成された水素の還元作用による減少分を差し引いた量であり、その時点で実際に三元触媒２２０に蓄積していると推定される硫黄の量である。 2, the ECU 100 calculates the corrected accumulation amount Asfcor based on the sulfur accumulation amount Asf acquired in step S101 and the in-catalyst hydrogen generation amount Ah2cat acquired in step S102 (step S103). The corrected accumulation amount Asfcor is an amount obtained by subtracting the reduction amount due to the reduction action of the hydrogen generated in the three-way catalyst 220 from the sulfur accumulated in the three-way catalyst 220. It is the amount of sulfur estimated to be accumulated in.
　補正後蓄積量Ａｓｆｃｏｒを算出すると、ＥＣＵ１００は、算出した補正後蓄積量Ａｓｆｃｏｒが基準値Ａｓｆｃｏｒｔｈよりも大きいか否かを判定する（ステップＳ１０４）。基準値Ａｓｆｃｏｒｔｈは、予め実験的に、経験的に又は理論的に、三元触媒２２０の浄化効率が所定以上に低下する値として決定されている。 When the corrected accumulation amount Asfcor is calculated, the ECU 100 determines whether or not the calculated corrected accumulation amount Asfcor is larger than the reference value Asfcorth (step S104). The reference value Asfcorth is previously determined experimentally, empirically, or theoretically as a value that reduces the purification efficiency of the three-way catalyst 220 to a predetermined value or more.
　補正後蓄積量Ａｓｆｃｏｒが基準値Ａｓｅｃｏｒｔｈ以下である場合（ステップＳ１０４：ＮＯ）、ＥＣＵ１００は、硫黄被毒回復制御を終了する。尚、硫黄被毒回復制御は、先述したように空燃比Ｆ／Ｂ制御の一サブルーチンであるから、空燃比Ｆ／Ｂ制御において実行条件が満たされた場合に再度実行される。 If the post-correction accumulation amount Asfcor is equal to or less than the reference value Asecorth (step S104: NO), the ECU 100 ends the sulfur poisoning recovery control. Since the sulfur poisoning recovery control is a subroutine of the air-fuel ratio F / B control as described above, it is executed again when the execution condition is satisfied in the air-fuel ratio F / B control.
　一方、補正後蓄積量Ａｓｆｃｏｒが、基準値Ａｓｆｃｏｒｔｈよりも大きい場合（ステップＳ１０４：ＹＥＳ）、ＥＣＵ１００は、三元触媒２２０に硫黄被毒回復の必要性があると判定し、ステップＳ１０５以降の処理を実行する。即ち、この場合、ＥＣＵ１００は、本発明に係る「判定手段」の一例として機能する。また、ステップＳ１０５からステップＳ１０９に至る処理は、本発明に係る「硫黄被毒回復」の一例である。 On the other hand, when the corrected accumulation amount Asfcor is larger than the reference value Asfcorth (step S104: YES), the ECU 100 determines that the three-way catalyst 220 needs to be recovered from sulfur poisoning, and performs the processing after step S105. Execute. That is, in this case, the ECU 100 functions as an example of the “determination unit” according to the present invention. Further, the process from step S105 to step S109 is an example of “sulfur poisoning recovery” according to the present invention.
　ステップＳ１０５では、Ｈ２要求量Ｎｈ２が算出される。Ｈ２要求量Ｎｈ２は、気筒２０１で生成させる必要がある水素量の要求量であり、本発明に係る「気筒における水素の要求量」の一例である。 In step S105, the required H2 amount Nh2 is calculated. The required H2 amount Nh2 is a required amount of hydrogen that needs to be generated in the cylinder 201, and is an example of the “required amount of hydrogen in the cylinder” according to the present invention.
　Ｈ２要求量Ｎｈ２は、ステップＳ１０３で算出された補正後蓄積量Ａｓｆｃｏｒに相当する硫黄を還元するために必要な水素量であり、その算出アルゴリズムは予め実験的に、経験的に又は理論的に与えられている。 The required H2 amount Nh2 is the amount of hydrogen necessary to reduce sulfur corresponding to the corrected accumulation amount Asfcor calculated in step S103, and its calculation algorithm is given experimentally, empirically or theoretically in advance. It has been.
　Ｈ２要求量Ｎｈ２が算出されると、ＥＣＵ１００は、各気筒における、空燃比のインバランス度ＩＭＢを決定する（ステップＳ１０６）。空燃比のインバランス度ＩＭＢは、気筒相互間の空燃比のばらつきの指標値であって、実践上は多様に定義し得る指標値である。本実施形態における空燃比のインバランス度ＩＭＢは、理論空燃比に対する、理論空燃比と各気筒の制御空燃比との偏差の割合として定義される。即ち、理論空燃比をＸとして、ある気筒の空燃比をＹとすると、当該気筒のインバランス度は（Ｘ－Ｙ）／Ｘ×１００（％）となる。 When the required H2 amount Nh2 is calculated, the ECU 100 determines the air-fuel ratio imbalance degree IMB in each cylinder (step S106). The air-fuel ratio imbalance degree IMB is an index value of variation in the air-fuel ratio between cylinders, and can be defined in various ways in practice. The air-fuel ratio imbalance degree IMB in this embodiment is defined as a ratio of a deviation between the theoretical air-fuel ratio and the control air-fuel ratio of each cylinder with respect to the theoretical air-fuel ratio. That is, if the theoretical air-fuel ratio is X and the air-fuel ratio of a certain cylinder is Y, the degree of imbalance of the cylinder is (XY) / X × 100 (%).
　例えば、理論空燃比（１４．６）に対し、ある気筒の空燃比が１０であるとすると、当該気筒のインバランス度は、約３２％となる。同様に、ある気筒の空燃比が１８であるとすると、その気筒のインバランス度は、約－２３％となる。尚、この場合、理論空燃比を介して間接的に各気筒の空燃比のばらつきの度合いが表されることになる。また、インバランス度ＩＭＢの決定とは、その定義に従えば、硫黄被毒回復制御における各気筒の空燃比の目標値を決定することと等価である。 For example, if the air-fuel ratio of a certain cylinder is 10 with respect to the theoretical air-fuel ratio (14.6), the imbalance degree of the cylinder is about 32%. Similarly, if the air-fuel ratio of a certain cylinder is 18, the imbalance degree of that cylinder is about −23%. In this case, the degree of variation in the air-fuel ratio of each cylinder is indirectly expressed through the theoretical air-fuel ratio. Further, the determination of the imbalance degree IMB is equivalent to determining the target value of the air-fuel ratio of each cylinder in the sulfur poisoning recovery control according to the definition.
　ＥＣＵ１００は、各気筒のインバランス度ＩＭＢを決定するにあたって、ＲＯＭに格納された第２水素濃度マップを参照する。ここで、図４を参照し、第２水素濃度マップについて説明する。ここに、図４は、第２水素濃度マップの概念図である。 The ECU 100 refers to the second hydrogen concentration map stored in the ROM when determining the imbalance degree IMB of each cylinder. Here, the second hydrogen concentration map will be described with reference to FIG. FIG. 4 is a conceptual diagram of the second hydrogen concentration map.
　図４において、縦軸及び横軸に夫々水素濃度及びインバランス度ＩＭＢ（％）が表される。インバランス度ＩＭＢ＝０とは、上述した定義により理論空燃比を意味する。 In FIG. 4, the vertical axis and the horizontal axis represent the hydrogen concentration and the imbalance degree IMB (%), respectively. The degree of imbalance IMB = 0 means the stoichiometric air-fuel ratio according to the above-described definition.
　このように、気筒内部では、空燃比が理論空燃比に対しリッチ側にあっても（正値）、リーン側にあっても（負値）、生成される水素の濃度は上昇する。しかしながら、通常の均質燃焼においては、リッチ側におけるリッチ失火限界よりもリーン側におけるリーン失火限界の方が、理論空燃比に対するマージンが少ない。従って、インバランス度ＩＭＢとして採り得る範囲は、リッチ側（正値）の方が広く、リッチ燃焼による水素生成の方が、可制御性が高くなっている。 Thus, even if the air-fuel ratio is on the rich side with respect to the stoichiometric air-fuel ratio (positive value) or on the lean side (negative value), the concentration of generated hydrogen increases inside the cylinder. However, in normal homogeneous combustion, the lean misfire limit on the lean side has a smaller margin for the stoichiometric air-fuel ratio than the rich misfire limit on the rich side. Therefore, the range that can be taken as the imbalance degree IMB is wider on the rich side (positive value), and the hydrogen generation by rich combustion has higher controllability.
　一方、インバランス度ＩＭＢに対する水素濃度は、機関回転数ＮＥ及び負荷率ＫＬに対しても変化する。例えば、ある基準の機関回転数ＮＥ及び負荷率ＫＬに対する特性を図示実線の特性とすると、機関回転数ＮＥが低い場合又は負荷率ＫＬが小さい場合には、水素濃度は減少する（図示鎖線参照）。また、機関回転数ＮＥが高い場合又は負荷率ＫＬが大きい場合には、水素濃度は上昇する（図示破線参照）。 On the other hand, the hydrogen concentration with respect to the imbalance degree IMB also changes with respect to the engine speed NE and the load factor KL. For example, if the characteristics with respect to a certain engine speed NE and load factor KL are the characteristics shown in the solid line in the figure, the hydrogen concentration decreases when the engine speed NE is low or the load factor KL is small (see the chain line in the figure). . Further, when the engine speed NE is high or the load factor KL is large, the hydrogen concentration increases (see the broken line in the drawing).
　第２水素濃度マップには、図示の関係が予め数値化された状態で格納されており、ＥＣＵ１００は、インバランス度ＩＭＢに対する水素濃度を、その時点の機関回転数ＮＥ及び負荷率ＫＬに基づいて推定することが出来る。また、機関回転数ＮＥ及び負荷率ＫＬに基づいて、単位時間に気筒から排出されるガスの総量を推定することが出来る。従って、ＥＣＵ１００は、あるインバランス度ＩＭＢが選択された気筒２０１における水素生成量Ｇｈ２を算出することが出来る。 In the second hydrogen concentration map, the relationship shown in the figure is stored in a numerical state in advance, and the ECU 100 determines the hydrogen concentration with respect to the imbalance degree IMB based on the engine speed NE and the load factor KL at that time. Can be estimated. Further, the total amount of gas discharged from the cylinder per unit time can be estimated based on the engine speed NE and the load factor KL. Therefore, the ECU 100 can calculate the hydrogen generation amount Gh2 in the cylinder 201 in which a certain imbalance degree IMB is selected.
　ここで、各気筒のインバランス度ＩＭＢは、エンジン２００に備わる気筒全体で、空燃比が先に述べた入力側目標空燃比ＡＦｉｎｔｇ又は理論空燃比に可及的に一致するように決定される。従って、気筒間にインバランスを生じさせるにあたって一の気筒２０１が空燃比リッチ側（又はリーン側）に制御される場合には、他の気筒の少なくとも一部はリーン側（又はリッチ側）に制御される。また、この際、エンジン２００の機関トルクの変動が可及的に少なくて済むように、リッチ側に制御される気筒とリーン側に制御される気筒とが、時系列上交互に燃焼行程を迎えるように、各気筒の空燃比が決定されてもよい。 Here, the imbalance degree IMB of each cylinder is determined so that the air-fuel ratio of the entire cylinder of the engine 200 matches the input target air-fuel ratio AFintg or the theoretical air-fuel ratio as much as possible. Therefore, when one cylinder 201 is controlled to the air-fuel ratio rich side (or lean side) when imbalance is generated between the cylinders, at least a part of the other cylinders is controlled to the lean side (or rich side). Is done. At this time, the cylinder controlled to the rich side and the cylinder controlled to the lean side alternately reach the combustion stroke in time series so that the fluctuation of the engine torque of the engine 200 is minimized. Thus, the air-fuel ratio of each cylinder may be determined.
　複数の気筒全体で空燃比を入力側目標空燃比Ａ／Ｆｉｎｔｇ又は理論空燃比に維持し得る各気筒のインバランス度ＩＭＢの組み合わせは無論一義的でない。例えば、先に述べた空燃比Ｆ／Ｂ制御のルーチンと同様に、リッチ気筒を除く残余の気筒のインバランス度ＩＭＢが決定されてもよいし、より単純には、全気筒の平均空燃比が理論空燃比又は入力側目標空燃比Ａ／Ｆｉｎｔｇとなるように、当該残余の気筒の暫定的な空燃比が決定されてもよい。 Of course, the combination of the imbalance degree IMB of each cylinder that can maintain the air-fuel ratio at the input side target air-fuel ratio A / Fintg or the stoichiometric air-fuel ratio in the plurality of cylinders as a whole is not unique. For example, as in the air-fuel ratio F / B control routine described above, the imbalance degree IMB of the remaining cylinders other than the rich cylinder may be determined, or more simply, the average air-fuel ratio of all the cylinders may be determined. The provisional air-fuel ratio of the remaining cylinders may be determined so that the theoretical air-fuel ratio or the input-side target air-fuel ratio A / Fintg is obtained.
　後者の手法とは、例えば、次のようなものを指す。例えば、４気筒エンジンを例に採り、気筒全体の平均空燃比を理論空燃比又は入力側目標空燃比Ａ／Ｆｉｎｔｇとするために必要な燃料量が「１０」である（即ち、各気筒の一サイクルに必要な燃料量が「２，５」である）とする。この場合、リッチ側に制御するリッチ気筒の燃料噴射量を「４」とすると、残余の３気筒で噴射すべき燃料量は「６」である。このような条件下で、残余の各気筒の燃料噴射量を「２」とする、或いは、残余の３気筒のうち２気筒について燃料噴射量を「２．５」に維持し、残余の一気筒のみ燃料噴射量を「１」とする。このようにしても、気筒全体の燃料噴射量は目標値に維持され、三元触媒２２０に流入する触媒流入ガスの平均空燃比を理論空燃比或いは入力側目標空燃比Ａ／Ｆｉｎｔｇに維持することが出来る。 The latter technique refers to the following, for example. For example, taking a four-cylinder engine as an example, the amount of fuel required to make the average air-fuel ratio of the entire cylinder the stoichiometric air-fuel ratio or the input-side target air-fuel ratio A / Fintg is “10” (that is, one cylinder The fuel amount required for the cycle is “2, 5”). In this case, if the fuel injection amount of the rich cylinder controlled to the rich side is “4”, the fuel amount to be injected in the remaining three cylinders is “6”. Under such conditions, the fuel injection amount of each remaining cylinder is set to “2”, or the fuel injection amount is maintained at “2.5” for two of the remaining three cylinders, and the remaining one cylinder Only the fuel injection amount is set to “1”. Even in this case, the fuel injection amount of the entire cylinder is maintained at the target value, and the average air-fuel ratio of the catalyst inflow gas flowing into the three-way catalyst 220 is maintained at the theoretical air-fuel ratio or the input-side target air-fuel ratio A / Fintg. I can do it.
　一方、気筒間で空燃比をインバランスさせる目的（三元触媒２２０からの硫黄の脱離）からすれば、少なくとも一の気筒２０１のインバランス度ＩＭＢは、先に算出されたＨ２要求量Ｎｈ２に応じて決定される。例えば、空燃比をリッチ側又はリーン側に制御した一の気筒から生成される水素のみで、ある有限の許容時間内にＨ２要求量Ｎｈ２を満たし得る場合には、当該一の気筒の空燃比のみを変化させ、気筒間でインバランスを生じさせてもよい。また、トルク変動を抑制する観点からは、可及的に多くの気筒の空燃比をリッチ側又はリーン側に制御し、上述したように燃焼行程をリッチ気筒→リーン気筒→リッチ気筒・・・で順次迎えるように各気筒のインバランス度を決定してもよい。尚、本実施形態においては、基本的に、硫黄被毒回復制御に要する時間を短縮化すべく、単位時間当たりの水素生成量が最も多くなるように、各気筒のインバランス度ＩＭＢが決定される。 On the other hand, if the purpose is to imbalance the air-fuel ratio between the cylinders (desorption of sulfur from the three-way catalyst 220), the imbalance degree IMB of at least one cylinder 201 is equal to the previously calculated H2 required amount Nh2. Will be decided accordingly. For example, when only the hydrogen generated from one cylinder whose air-fuel ratio is controlled to the rich side or lean side can satisfy the H2 requirement amount Nh2 within a certain finite allowable time, only the air-fuel ratio of the one cylinder May be changed to cause an imbalance between the cylinders. Further, from the viewpoint of suppressing torque fluctuation, the air-fuel ratio of as many cylinders as possible is controlled to the rich side or the lean side, and the combustion stroke is rich cylinder → lean cylinder → rich cylinder as described above. You may determine the imbalance degree of each cylinder so that it may meet sequentially. In the present embodiment, basically, in order to shorten the time required for the sulfur poisoning recovery control, the imbalance degree IMB of each cylinder is determined so as to maximize the amount of hydrogen generated per unit time. .
　図２に戻り、各気筒についてインバランス度ＩＭＢ（即ち、一義的に空燃比の目標値）が決定されると、ＥＣＵ１００は、決定されたインバランス度ＩＭＢに従って、各気筒の目標空燃比を切り替える（ステップＳ１０７）。目標空燃比を切り替えることにより、通常の燃料噴射制御ルーチンに従って、ポート噴射インジェクタ２１２が駆動制御され、気筒間でインバランスを生じさせるための燃料噴射が実現される。 Returning to FIG. 2, when the imbalance degree IMB (ie, the target value of the air-fuel ratio) is determined for each cylinder, the ECU 100 switches the target air-fuel ratio of each cylinder according to the determined imbalance degree IMB. (Step S107). By switching the target air-fuel ratio, the port injector 212 is driven and controlled in accordance with a normal fuel injection control routine, and fuel injection for causing imbalance between cylinders is realized.
　このようにインバランス制御が実行されると、ＥＣＵ１００は、インバランス制御開始以降の気筒全体での水素生成量ΣＧｈ２を、各気筒の水素生成量Ｇｈ２の積算値としてカウントする（ステップＳ１０８）。続いて、カウントされる水素生成量ΣＧｈ２が先に算出されたＨ２要求量Ｎｈ２を超えたか否かが判定され（ステップＳ１０９）、水素生成量ΣＧｈ２がＨ２要求量Ｎｈ２以下である場合には（ステップＳ１０９：ＮＯ）、処理はステップＳ１０８に戻され、インバランス制御が継続される。 When the imbalance control is executed in this way, the ECU 100 counts the hydrogen generation amount ΣGh2 in the entire cylinder after the start of the imbalance control as an integrated value of the hydrogen generation amount Gh2 of each cylinder (step S108). Subsequently, it is determined whether or not the counted hydrogen generation amount ΣGh2 has exceeded the previously calculated H2 required amount Nh2 (step S109). (S109: NO), the process is returned to step S108, and the imbalance control is continued.
　水素生成量ΣＧｈ２がＨ２要求量Ｎｈ２よりも大きくなると（ステップＳ１０９：ＹＥＳ）、ＥＣＵ１００は、硫黄蓄積量Ａｓｆがクリアされるように、硫黄蓄積量推定用のサブルーチンを制御し（ステップＳ１１０）、硫黄被毒回復制御を終了する。 When the hydrogen generation amount ΣGh2 becomes larger than the H2 required amount Nh2 (step S109: YES), the ECU 100 controls the sulfur accumulation amount estimation subroutine so that the sulfur accumulation amount Asf is cleared (step S110). End poisoning recovery control.
　尚、ここでは、水素生成量ΣＧｈ２とＨ２要求量Ｎｈ２との比較がなされるが、空燃比のインバランスにより気筒内で水素を生成している期間においても、三元触媒２２０における水素生成は別途進行する。従って、ＥＣＵ１００は、空燃比のインバランスにより硫黄被毒回復を図る期間において、触媒内水素生成量Ａｈ２ｃａｔを水素生成量ΣＧｈ２に加算してステップＳ１０９を実行してもよい。或いは、予めＨ２要求量Ｎｈ２を算出するにあたって触媒内水素生成量Ａｈ２ｃａｔを考慮して、本実施形態に係るＨ２要求量Ｎｈ２を減量側に補正してもよい。 Here, the hydrogen generation amount ΣGh2 and the H2 required amount Nh2 are compared, but hydrogen generation in the three-way catalyst 220 is separately performed even during a period in which hydrogen is generated in the cylinder due to the air-fuel ratio imbalance. proceed. Therefore, the ECU 100 may execute step S109 by adding the in-catalyst hydrogen generation amount Ah2cat to the hydrogen generation amount ΣGh2 during the period of recovery from sulfur poisoning due to the air-fuel ratio imbalance. Alternatively, the H2 required amount Nh2 according to the present embodiment may be corrected to the decreasing side in consideration of the in-catalyst hydrogen generation amount Ah2cat in calculating the H2 required amount Nh2.
　以上説明したように、本実施形態に係る硫黄被毒回復制御によれば、気筒間で空燃比のインバランスを生じさせることにより、コストの増加を招くことなく三元触媒２２０の硫黄被毒を回復させることが可能である。また、気筒全体の空燃比が理論空燃比又は入力側目標空燃比Ａ／Ｆｉｎｔｇとなるように各気筒のインバランス度ＩＭＢが決定されるので、三元触媒２２０に流入する触媒流入ガスの空燃比の時間平均値は、殆ど理論空燃比又は入力側目標空燃比Ａ／Ｆｉｎｔｇに維持される。従って、排気エミッション及び燃費の悪化を抑制しつつ三元触媒２２０の硫黄被毒を効率的且つ効果的に回復させることが出来る。 As described above, according to the sulfur poisoning recovery control according to this embodiment, the sulfur poisoning of the three-way catalyst 220 is reduced without causing an increase in cost by causing an air-fuel ratio imbalance between the cylinders. It is possible to recover. Further, since the degree of imbalance IMB of each cylinder is determined so that the air-fuel ratio of the entire cylinder becomes the stoichiometric air-fuel ratio or the input-side target air-fuel ratio A / Fintg, the air-fuel ratio of the catalyst inflow gas flowing into the three-way catalyst 220 Is substantially maintained at the theoretical air fuel ratio or the input side target air fuel ratio A / Fintg. Therefore, sulfur poisoning of the three-way catalyst 220 can be efficiently and effectively recovered while suppressing deterioration of exhaust emission and fuel consumption.
　尚、第１実施形態では、空燃比のインバランスを生じさせる装置として吸気ポートインジェクタ２１２が使用されている。空燃比のインバランスが気筒内に吸入される空気量と燃料噴射量とに依存する点からすれば、燃料噴射装置は、この種の装置として妥当且つ適当であるが、空燃比のインバランス度ＩＭＢを変化させ得る制御量は、燃料噴射量以外にも存在する。例えば、このような制御量としては、吸気弁の開閉時期やＥＧＲ装置のＥＧＲ率がある。 In the first embodiment, the intake port injector 212 is used as a device for generating an air-fuel ratio imbalance. In view of the fact that the air-fuel ratio imbalance depends on the amount of air sucked into the cylinder and the fuel injection amount, the fuel injection device is reasonable and appropriate as this type of device. There is a control amount that can change the IMB in addition to the fuel injection amount. For example, such control amounts include the opening / closing timing of the intake valve and the EGR rate of the EGR device.
　例えば、吸気弁２０９の開閉時期を遅角側にシフトさせると、閉弁時期ＩＶＣ付近において吸気の吹き返しにより吸入空気量が低下する。従って、燃料噴射量が一定であれば、空燃比は相対的にリッチ側にシフトする。エンジン２００においては、吸気弁２０９の開閉時期が各気筒独立して制御可能であるから、開閉時期の制御により空燃比のインバランスを生じさせることが出来る。 For example, when the opening / closing timing of the intake valve 209 is shifted to the retard side, the intake air amount decreases due to the return of intake air in the vicinity of the valve closing timing IVC. Therefore, if the fuel injection amount is constant, the air-fuel ratio shifts relatively to the rich side. In the engine 200, since the opening / closing timing of the intake valve 209 can be controlled independently for each cylinder, the air-fuel ratio imbalance can be generated by controlling the opening / closing timing.
　また、エンジン２００は、より好適には、各気筒の吸気弁２０９又は排気弁２１５の作用角又はバルブリフト量を独立して制御可能な機構を備えていてもよい。作用角又はバルブリフト量が気筒毎に独立して制御可能であれば、気筒毎の吸入空気量について比較的大きな制御幅を獲得することが出来る。従って、空燃比のインバランスの制御幅を比較的大きく採ることが出来る。このような機構は、例えば、気筒毎に吸気弁又は排気弁を開閉駆動する電磁駆動装置等を備えるものであってもよい。 Further, the engine 200 may more preferably include a mechanism capable of independently controlling the operating angle or valve lift amount of the intake valve 209 or the exhaust valve 215 of each cylinder. If the operating angle or valve lift amount can be controlled independently for each cylinder, a relatively large control range can be obtained for the intake air amount for each cylinder. Therefore, the control range of the air-fuel ratio imbalance can be made relatively large. Such a mechanism may include, for example, an electromagnetic drive device that opens and closes an intake valve or an exhaust valve for each cylinder.
　或いは、各気筒独立して吸気絞り弁を有する構成としてもよい。この場合、バルブの開閉特性が各気筒について一律であっても、気筒毎に吸入空気量に変化を与えることが出来る。即ち、空燃比のインバランスを生じさせることが出来る。 Alternatively, each cylinder may have an intake throttle valve independently. In this case, even if the opening / closing characteristics of the valve are uniform for each cylinder, the intake air amount can be changed for each cylinder. That is, an air-fuel ratio imbalance can be generated.
　ＥＧＲ装置もまた、空燃比のインバランスを生じさせる装置として使用可能である。例えば、各気筒の吸気ポート２０８に独立したＥＧＲ管２１７を接続する構成とすれば、各ＥＧＲ管に備わるＥＧＲ弁の開閉状態の制御により、気筒毎にＥＧＲ率を独立して制御することが出来る。その結果、筒内吸入ガスに対する新気の割合を変化させることができ、空燃比のインバランスを生じさせることが出来る。 The EGR device can also be used as a device that causes an air-fuel ratio imbalance. For example, if an independent EGR pipe 217 is connected to the intake port 208 of each cylinder, the EGR rate can be independently controlled for each cylinder by controlling the open / close state of the EGR valve provided in each EGR pipe. . As a result, the ratio of fresh air to in-cylinder intake gas can be changed, and an air-fuel ratio imbalance can be generated.
　尚、本実施形態では、硫黄蓄積量Ａｓｆと触媒内水素生成量Ａｈ２ｃａｔとに基づいて本発明に係る「硫黄被毒回復を実施するか否か」に係る判定がなされるが、これは一例であり、ＥＣＵ１００は、硫黄蓄積量Ａｓｆのみに基づいて係る判定を行ってもよい。例えば、硫黄蓄積量Ａｓｆが所定値以上である場合にステップＳ１０５以降の処理を実行してもよい。 In this embodiment, the determination regarding whether or not to perform sulfur poisoning recovery is performed based on the sulfur accumulation amount Asf and the in-catalyst hydrogen generation amount Ah2cat, but this is an example. Yes, the ECU 100 may perform the determination based only on the sulfur accumulation amount Asf. For example, when the sulfur accumulation amount Asf is greater than or equal to a predetermined value, the processing after step S105 may be executed.
　或いは、ＥＣＵ１００は、触媒内水素生成量Ａｈ２ｃａｔのみに基づいて係る判定をおこなってもよい。例えば、所定期間における触媒内水素生成量Ａｈ２ｃａｔが基準値以下である場合に、硫黄被毒回復の必要性が大であるとして硫黄被毒回復のための処理を行うべき旨の判定を下してもよい。 Alternatively, the ECU 100 may make the determination based only on the in-catalyst hydrogen generation amount Ah2cat. For example, when the amount of hydrogen generated in the catalyst Ah2cat in a predetermined period is equal to or less than a reference value, it is determined that the processing for sulfur poisoning recovery should be performed because the necessity for sulfur poisoning recovery is large. Also good.
　＜第２実施形態＞
　第１実施形態では、硫黄被毒回復制御において、気筒間で空燃比のインバランスを生じさせるのみであるが、三元触媒２２０の温度領域を制御することにより、きめ細かい制御が可能となる場合がある。第２実施形態では、このような硫黄被毒回復制御について説明する。 <Second Embodiment>
In the first embodiment, in the sulfur poisoning recovery control, only an air-fuel ratio imbalance is generated between the cylinders. However, by controlling the temperature region of the three-way catalyst 220, fine control may be possible. is there. In the second embodiment, such sulfur poisoning recovery control will be described.
　ここで、図５を参照し、第２実施形態に係る硫黄被毒回復制御の詳細について説明する。ここに、図５は、硫黄被毒回復制御のフローチャートである。尚、同図において、図２と重複する箇所には同一の符号を付してその説明を適宜省略することとする。 Here, the details of the sulfur poisoning recovery control according to the second embodiment will be described with reference to FIG. FIG. 5 is a flowchart of the sulfur poisoning recovery control. In the figure, the same reference numerals are given to the same portions as those in FIG. 2, and the description thereof will be omitted as appropriate.
　図５において、各気筒２０１の空燃比インバランス度ＩＭＢを決定すると、即ち、各気筒２０１の目標空燃比を決定すると、ＥＣＵ１００は、点火装置２１３による点火時期の遅角量を算出する（ステップＳ２０１）。 In FIG. 5, when the air-fuel ratio imbalance degree IMB of each cylinder 201 is determined, that is, when the target air-fuel ratio of each cylinder 201 is determined, the ECU 100 calculates the retard amount of the ignition timing by the ignition device 213 (step S201). ).
　点火時期を遅角すると、気筒内の燃焼反応が全体的に遅角側に推移することから、排気管２１９及び三元触媒２２０の昇温が促進される。ここで、触媒床温Ｔｃａｔは、既に述べたように三元触媒２２０での水素生成量（触媒内水素生成量Ａｈ２ｃａｔ）に影響する。触媒床温Ｔｃａｔは、空燃比のリッチ化を伴う空燃比インバランス制御においても上昇するが、一の制御要素である空燃比インバランス度ＩＭＢで、水素生成量Ｇｈ２と触媒床温Ｔｃａｔの二つの状態量を独立に制御することは出来ない。そこで、触媒床温Ｔｃａｔを制御するための制御要素として点火時期の遅角量が利用されるのである。 When the ignition timing is retarded, the combustion reaction in the cylinder shifts to the retard side as a whole, so that the temperature rise of the exhaust pipe 219 and the three-way catalyst 220 is promoted. Here, the catalyst bed temperature Tcat affects the amount of hydrogen generated in the three-way catalyst 220 (in-catalyst hydrogen generation amount Ah2cat) as described above. The catalyst bed temperature Tcat also increases in the air-fuel ratio imbalance control accompanied by the enrichment of the air-fuel ratio. However, the air-fuel ratio imbalance degree IMB as one control element has two hydrogen generation amounts Gh2 and catalyst bed temperature Tcat. The state quantity cannot be controlled independently. Therefore, the retard amount of the ignition timing is used as a control element for controlling the catalyst bed temperature Tcat.
　点火時期の遅角量は、例えば、点火時期の遅角により硫黄被毒回復制御の実行期間を短縮化し得る場合に実行される。或いは、インバランス度ＩＭＢが大き過ぎることにより燃焼状態の悪化が他に影響を与え得るときに、係る影響を触媒床温Ｔｃａｔの上昇により緩和し得るように実行される。点火時期遅角量が算出されると、目標空燃比の切り替え制御（インバランス制御）に引き続いて、点火時期の遅角制御が実行される（ステップＳ２０２）。 The retard amount of the ignition timing is executed, for example, when the execution period of the sulfur poisoning recovery control can be shortened by the retard of the ignition timing. Alternatively, when the imbalance degree IMB is too large and the deterioration of the combustion state can affect other factors, the effect is executed so that the influence can be mitigated by increasing the catalyst bed temperature Tcat. When the ignition timing retardation amount is calculated, ignition timing retardation control is executed following the target air-fuel ratio switching control (imbalance control) (step S202).
　第２実施形態によれば、点火時期の遅角により、気筒内の水素生成量Ｇｈ２と触媒床温Ｔｃａｔとを独立して制御することが可能となるため、三元触媒２２０の硫黄被毒を回復させるにあたって、気筒内の燃焼状態をより望ましいものとすることが出来る。 According to the second embodiment, since the hydrogen generation amount Gh2 in the cylinder and the catalyst bed temperature Tcat can be independently controlled by retarding the ignition timing, the sulfur poisoning of the three-way catalyst 220 is prevented. In the recovery, the combustion state in the cylinder can be made more desirable.
　本発明は、上述した実施形態に限られるものではなく、請求の範囲及び明細書全体から読み取れる発明の要旨或いは思想に反しない範囲で適宜変更可能であり、そのような変更を伴う内燃機関の制御装置もまた本発明の技術的範囲に含まれるものである。 The present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist or concept of the invention that can be read from the claims and the entire specification, and the control of the internal combustion engine accompanying such a change. The apparatus is also included in the technical scope of the present invention.
　本発明は、内燃機関における触媒の硫黄被毒回復制御に適用可能である。 The present invention can be applied to sulfur poisoning recovery control of a catalyst in an internal combustion engine.
　１０…エンジンシステム、１００…ＥＣＵ、２００…エンジン、ＣＢ…シリンダブロック、２０１…気筒、２１２…吸気ポートインジェクタ、２１９…排気管、２２０…三元触媒、２２１…空燃比センサ、２２２…Ｏ２センサ。 10 ... engine system, 100 ... ECU, 200 ... engine, CB ... Cylinder block, 201 ... cylinder, 212 ... intake port injector, 219 ... exhaust pipe, 220 ... three-way catalyst, 221 ... air-fuel ratio sensor, 222 ... O 2 sensor .

Claims (10)

  1. 　複数の気筒と、
    　前記複数の気筒に繋がる排気経路に設置された排気浄化用の触媒と
    　を備えた内燃機関を制御する、内燃機関の制御装置であって、
    　前記触媒の硫黄被毒回復を実施するか否かを判定する判定手段と、
    　前記硫黄被毒回復を実施すると判定された場合に、前記触媒に流入する排気の空燃比を制御する被毒回復制御手段と
    　を具備し、
    　前記被毒回復制御手段は、前記複数の気筒相互間における前記空燃比のインバランス度を制御する
    　ことを特徴とする内燃機関の制御装置。     Multiple cylinders,
    An internal combustion engine control device for controlling an internal combustion engine comprising an exhaust purification catalyst installed in an exhaust path connected to the plurality of cylinders,
    Determining means for determining whether or not to perform sulfur poisoning recovery of the catalyst;
    Poisoning recovery control means for controlling the air-fuel ratio of the exhaust gas flowing into the catalyst when it is determined to carry out the sulfur poisoning recovery, and
    The control apparatus for an internal combustion engine, wherein the poisoning recovery control means controls the degree of imbalance of the air-fuel ratio among the plurality of cylinders.
  2. 　前記触媒における硫黄の蓄積量を推定する蓄積量推定手段を更に具備し、
    　前記判定手段は、前記推定された蓄積量に基づいて前記硫黄被毒回復を実施するか否かを判定する
    　ことを特徴とする請求の範囲第１項に記載の内燃機関の制御装置。     Further comprising accumulation amount estimating means for estimating the accumulation amount of sulfur in the catalyst;
    The control device for an internal combustion engine according to claim 1, wherein the determination means determines whether or not to perform the sulfur poisoning recovery based on the estimated accumulation amount.
  3. 　前記触媒における水素の生成量を推定する触媒内生成量推定手段を更に具備し、
    　前記判定手段は、前記推定された触媒における水素の生成量に基づいて前記硫黄被毒回復を実施するか否かを判定する
    　ことを特徴とする請求の範囲第１項又は第２項に記載の内燃機関の制御装置。     Further comprising in-catalyst production amount estimation means for estimating the amount of hydrogen produced in the catalyst,
    The said determination means determines whether the said sulfur poisoning recovery | restoration is implemented based on the estimated production amount of hydrogen in the said catalyst. The Claim 1 or 2 characterized by the above-mentioned. Control device for internal combustion engine.
  4. 　前記触媒内生成量推定手段は、前記触媒における水素の生成量として、水性ガスシフト反応及び水蒸気改質反応による水素の生成量を推定する
    　ことを特徴とする請求の範囲第３項に記載の内燃機関の制御装置。     The internal combustion engine according to claim 3, wherein the in-catalyst production amount estimation means estimates the production amount of hydrogen due to a water gas shift reaction and a steam reforming reaction as the production amount of hydrogen in the catalyst. Control device.
  5. 　前記触媒における硫黄の蓄積量を推定する蓄積量推定手段と、
    　前記触媒における水素の生成量を推定する触媒内生成量推定手段と
    　を具備し、
    　前記判定手段は、前記推定された触媒における硫黄の蓄積量と前記推定された触媒における水素の生成量とに基づいて前記硫黄被毒回復を実施するか否かを判定する
    　ことを特徴とする請求の範囲第１項に記載の内燃機関の制御装置。     Accumulated amount estimating means for estimating the accumulated amount of sulfur in the catalyst;
    And an in-catalyst production amount estimating means for estimating the production amount of hydrogen in the catalyst,
    The determination means determines whether or not to perform the sulfur poisoning recovery based on the estimated sulfur accumulation amount in the catalyst and the estimated hydrogen generation amount in the catalyst. 2. A control device for an internal combustion engine as set forth in claim 1.
  6. 　前記触媒における硫黄の蓄積量を推定する蓄積量推定手段と、
    　前記触媒における水素の生成量を推定する触媒内生成量推定手段と、
    　前記推定された硫黄の蓄積量と、前記推定された触媒における水素の生成量とに基づいて、前記気筒における水素の要求量を推定する要求量推定手段と、
    　前記インバランス度の制御による前記気筒における水素の生成量を推定する筒内生成量推定手段と
    　を具備し、
    　前記被毒回復制御手段は、前記推定された要求量が得られるように前記推定された気筒における水素の生成量に基づいて前記インバランス度を制御する
    　ことを特徴とする請求の範囲第１項に記載の内燃機関の制御装置。     Accumulated amount estimating means for estimating the accumulated amount of sulfur in the catalyst;
    In-catalyst production amount estimation means for estimating the amount of hydrogen produced in the catalyst;
    Requested amount estimating means for estimating a required amount of hydrogen in the cylinder based on the estimated amount of accumulated sulfur and the estimated amount of hydrogen generated in the catalyst;
    In-cylinder production amount estimation means for estimating the amount of hydrogen production in the cylinder by controlling the degree of imbalance,
    The said poisoning recovery control means controls the said imbalance degree based on the production amount of hydrogen in the estimated cylinder so that the estimated demand amount can be obtained. The control apparatus of the internal combustion engine described in 1.
  7. 　前記触媒内生成量推定手段は、前記インバランス度の制御により変化する前記触媒の温度に基づいて、前記触媒における水素の生成量を推定する
    　ことを特徴とする請求の範囲第６項に記載の内燃機関の制御装置。     The in-catalyst production amount estimation means estimates the production amount of hydrogen in the catalyst based on the temperature of the catalyst that changes by controlling the degree of imbalance. Control device for internal combustion engine.
  8. 　前記内燃機関は、
    　前記触媒に流入する排気の空燃比相当値を検出する第１検出手段と、
    　前記触媒から排出される排気の空燃比相当値を検出する第２検出手段と
    　を更に具備し、
    　前記内燃機関の制御装置は、
    　前記検出される触媒に流入する排気の空燃比相当値及び前記検出される触媒から排出される排気の空燃比相当値に基づいて、前記触媒の内部の空燃比を目標空燃比に収束させる空燃比制御手段を更に具備する
    　ことを特徴とする請求の範囲第１項に記載の内燃機関の制御装置。     The internal combustion engine
    First detecting means for detecting an air-fuel ratio equivalent value of exhaust gas flowing into the catalyst;
    A second detecting means for detecting an air-fuel ratio equivalent value of the exhaust gas discharged from the catalyst;
    The control device for the internal combustion engine includes:
    An air-fuel ratio for converging the air-fuel ratio in the catalyst to a target air-fuel ratio based on the air-fuel ratio equivalent value of the exhaust gas flowing into the detected catalyst and the air-fuel ratio equivalent value of the exhaust gas discharged from the detected catalyst The control device for an internal combustion engine according to claim 1, further comprising control means.
  9. 　前記被毒回復制御手段は、燃料噴射装置、吸気弁及び排気弁の少なくとも一方の開閉時期を変化させることが可能な可変動弁装置並びにＥＧＲ装置のうち少なくとも一つを制御する
    　ことを特徴とする請求の範囲第１項に記載の内燃機関の制御装置。     The poisoning recovery control means controls at least one of a fuel injection device, a variable valve device capable of changing an opening / closing timing of at least one of an intake valve and an exhaust valve, and an EGR device. The control device for an internal combustion engine according to claim 1.
  10. 　前記内燃機関は、燃料としてガソリンを使用する内燃機関、燃料として軽油を使用する圧縮自着火式内燃機関、又は、成層燃焼により空燃比がリーン空燃比に維持される燃焼希薄燃焼内燃機関である
    　ことを特徴とする請求の範囲第１項に記載の内燃機関の制御装置。     The internal combustion engine is an internal combustion engine that uses gasoline as a fuel, a compression auto-ignition internal combustion engine that uses light oil as a fuel, or a combustion lean combustion internal combustion engine in which the air-fuel ratio is maintained at a lean air-fuel ratio by stratified combustion. The control apparatus for an internal combustion engine according to claim 1, characterized in that:
PCT/JP2012/059724 2012-04-09 2012-04-09 Control device for internal combustion engine WO2013153610A1 (en)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005207404A (en) * 2003-12-26 2005-08-04 Denso Corp Air fuel ratio control device of internal combustion engine
JP2006242124A (en) * 2005-03-04 2006-09-14 Toyota Motor Corp Exhaust emission control device for internal combustion engine
JP2007154840A (en) * 2005-12-08 2007-06-21 Toyota Motor Corp Air-fuel ratio control device of internal combustion engine
JP2009022821A (en) * 2007-07-17 2009-02-05 Honda Motor Co Ltd NOx PURIFYING CATALYST
JP2010174739A (en) * 2009-01-29 2010-08-12 Toyota Motor Corp Exhaust emission control device for internal combustion engine

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005207404A (en) * 2003-12-26 2005-08-04 Denso Corp Air fuel ratio control device of internal combustion engine
JP2006242124A (en) * 2005-03-04 2006-09-14 Toyota Motor Corp Exhaust emission control device for internal combustion engine
JP2007154840A (en) * 2005-12-08 2007-06-21 Toyota Motor Corp Air-fuel ratio control device of internal combustion engine
JP2009022821A (en) * 2007-07-17 2009-02-05 Honda Motor Co Ltd NOx PURIFYING CATALYST
JP2010174739A (en) * 2009-01-29 2010-08-12 Toyota Motor Corp Exhaust emission control device for internal combustion engine

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