WO2011125079A1 - Système et procédé de commande de moteurs à carburateur équipés d'une sonde lambda - Google Patents
Système et procédé de commande de moteurs à carburateur équipés d'une sonde lambda Download PDFInfo
- Publication number
- WO2011125079A1 WO2011125079A1 PCT/IT2010/000148 IT2010000148W WO2011125079A1 WO 2011125079 A1 WO2011125079 A1 WO 2011125079A1 IT 2010000148 W IT2010000148 W IT 2010000148W WO 2011125079 A1 WO2011125079 A1 WO 2011125079A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- control
- clc
- carburettor
- sensor
- signal
- Prior art date
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D35/00—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for
- F02D35/0015—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for using exhaust gas sensors
- F02D35/0023—Controlling air supply
- F02D35/003—Controlling air supply by means of by-pass passages
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D35/00—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for
- F02D35/0015—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for using exhaust gas sensors
- F02D35/0046—Controlling fuel supply
- F02D35/0053—Controlling fuel supply by means of a carburettor
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/02—Circuit arrangements for generating control signals
- F02D41/14—Introducing closed-loop corrections
- F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
- F02D41/1473—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the regulation method
- F02D41/1475—Regulating the air fuel ratio at a value other than stoichiometry
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/02—Circuit arrangements for generating control signals
- F02D41/14—Introducing closed-loop corrections
- F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
- F02D41/1477—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the regulation circuit or part of it,(e.g. comparator, PI regulator, output)
- F02D41/1482—Integrator, i.e. variable slope
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/02—Circuit arrangements for generating control signals
- F02D41/14—Introducing closed-loop corrections
- F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
- F02D41/1477—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the regulation circuit or part of it,(e.g. comparator, PI regulator, output)
- F02D41/1483—Proportional component
Definitions
- the present invention concerns an electronic control system for the preparation, dosing and ignition of the mixture of air and fuel in internal combustion engines.
- it concerns such a system for carburettor-supplied internal combustion engines .
- ECU electronic central units
- These units by reading and analysing a certain number of operation parameters, are designed to adjust, in an optimised manner, the control of a series of actuation devices which determine the dosing of the fuel mixture by means of adjustable carburettors (for example with bypass valves) and combustion conditions (acting also on the adjustment of the spark advance) .
- Adjustable carburettors for such applications comprise an auxiliary air conduit (bypass air) the flow of which is controllable in various ways by means of electric device, such as solenoid valves .
- the object of the present invention is hence that of providing a control system of the combustion of controller-ignition engines, which overcomes the mentioned drawbacks and which is even more effective than known systems, being able to employ also a feed-back signal relative to the composition of exhaust gases.
- an electronic control system of the opera ⁇ tion of carburettor-supplied internal combustion engines comprising a control unit suited to drive at least one electrovalve device for the adjustment of the emulsion air of the carburettor which determines the air/fuel ratio (AFR) of the fuel mixture and further comprising an 0 2 sensor probe arranged for reading the composition of exhaust gases and for sending a signal of the amount of 0 2 towards said control unit, wherein said 0 2 sensor operates switching between two states of 0 2 (Lean02Threshold, Rich02Threshold) and the control of said elec- trovalve device for the carburettor adjustment is a closed loop control based on said two 0 2 states.
- said closed loop control is built as the sum of a step term, which determines a control jump, with a plurality of increment terms, which deter ⁇ mine a control ramp, where the step term is greater than the increment term.
- StepL, StepR different step terms
- IncrL, IncrR different increment terms
- control of said electrovalve device for carburettor adjustment is performed with PWM technique and the drive PWM signal issued by the control unit (ECU) consists of
- PWMbase is the signal generated in conditions in which the signal coming from the 0 2 sensor is disregarded.
- the CLC signal is used to trim the AFR offset compared to the stoichiometric conditions of a preset amount.
- a further aspect of the invention is that said 0 2 sensor probe is of the single-wire, non-preheated type, mounted close to the exhaust port of the engine.
- a control method of the operation of internal combustion, carburettor- supplied engines comprising a device for the adjustment of the emulsion air of the carburettor which determines the air/ fuel ratio (AFR) of the fuel mixture as well as an 0 2 sensor probe arranged to issue a signal (02State) of the amount of 0 2 in the exhaust gases, said 0 2 sensor switching between two 0 2 states (Lean02Threshold, Rich02Threshold) , wherein
- control factor (CLC) is calculated in a closed loop based on said two 0 2 states
- step term which determines a control jump
- step term which deter ⁇ mine a control ramp
- fig. 1 is a diagram of interactions in the closed loop system according to the invention,- and
- figs. 2 and 3 are plots of 0 2 probe voltage signal showing two different operating conditions, whose comparison gives an idea of good and bad drivability;
- fig. 4 is a plot of some monitored values according to the prior art.
- fig. 5 is a similar plot as in fig. 4 but using the system of the invention.
- a control system of a carburettor vehicle substantially comprises a central electronic control unit (ECU) - provided with a logical unit wherein the control strate- gies are implemented (through suitable software and/or firmware) - a series of detection sensors of the fundamental operation parameters and a series of actuators which are diagrammatically clearly identified in the drawing.
- ECU central electronic control unit
- An electronically controllable carburettor typically has one or more solenoid actuators for controlling the A/F (air/fuel) ration of the mixture, acting on the supplemental (emulsion) air circuit in addition to the main (emulsion) air adjusted through a traditional throttle.
- the system is preferably provided with capacitive discharge ignition (CDI) with variable and controllable spark advance, although it is possible to employ also simpler inductive discharge ignitions .
- CDI capacitive discharge ignition
- the control strategy which must take into account the specific operation conditions, i.e. the low operation frequency of the electrovalve on the carburettor, the control mode of the elec- trovalve in PWM and the need to prepare an A/F mixture suited to a carburettor.
- the control strategy of the electrovalve on the carburettor, implemented in the electronic unit takes into account the availability of a closed loop sig- nal, i.e. a signal coming from an oxygen probe arranged in the exhaust pipe of the engine.
- a closed loop sig- nal i.e. a signal coming from an oxygen probe arranged in the exhaust pipe of the engine.
- the probe which one wants to employ must be suited to operate simply and to quickly achieve full functionality, to avoid complicating the system to take into account transient and complex operation conditions.
- the oxygen probe (so-called lambda probe) is of the single-wire type, hence not electrically heated. It has a reduced size and is mounted directly at engine exhaust, i.e. downstream of the exhaust valve.
- This mounting made possi- ble by the presence of a single wire (the ground pole is obtained by mounting locally the probe in contact with the engine and/or exhaust metal parts) and by the small size of the probe, ensures that the probe warms up quickly (even without having conductors which provide to the preheating thereof) , can quickly achieve full functionality and can operate also without the need to install a battery connected to the system.
- the transmittable signal to the control unit is simplified, with respect to what exists in the prior art.
- the probe is capable of operating between two extreme switching conditions, i.e. between a condition in which a signal "rich mixture” is issued and a condition in which a signal “lean mixture” is issued, based on the exceeding of thresholds of detected 0 2 .
- the closed loop control provided for the sys- tern of the invention is based on a switching control between rich and lean conditions, detected by an unheated switching 0 2 sensor.
- the closed loop control is enabled only when the engine is warm, the 0 2 sensor is ready and the driving style is not aggressive .
- the advantage of using an 0 2 probe is to be able to obtain an optimal adjustment of the fuel mixture (in the controlled carburettor) , as well as to be able to employ catalytic converters which cut down polluting emissions.
- Another significant advantage inherent in the use of a feedback signal, simplified as it may be, is that of also being able to compensate production engine variability, engine ageing, carburettor ageing, 0 2 sensor ageing, altitude conditions, air- box filter clogging, fuel quality, etc.
- the feedback signal coming from the 0 2 sensor, according to the invention is hence entered in the ECU to change the basic control strategy of the carburettor, in particular of the elec- trovalve of the air by-pass duct (and hence adjusting as desired the air/fuel ratio) .
- the AFR air/fuel ratio
- the AFR air/fuel ratio
- the unheated switching oxygen sensor voltage output signal is used for AFR compensation in closed loop control.
- An oxygen sensor in the exhaust gas is used to detect the actual rich or lean condition of the AFR.
- the sensor switches between two different voltage values (Clc_Lean02 and Clc_Rich02) which are supplied to the control unit (ECU) .
- said 0 2 sensor feedback is used by the logic implemented in the ECU to trim the AFR back to stoichiometric conditions or outside the stoichiometric condition of a preset value, depending on the situation.
- the sensor output is high, compared to a preset threshold, it means the fuel mixture is rich and vice versa.
- the 0 2 sensor is arranged close to the exhaust port of the engine.
- the 0 2 sensor probe must not affect the flow capacity of the exhaust system, i.e. limiting the cross section of the exhaust pipe.
- the exhaust pipe shall be preferably free from air leaks.
- the 0 2 sensor is properly grounded via the exhaust pipe, then only one wire and one ECU input pin is used.
- the input stage is implemented on a board within the ECU and provides, among other things, also to A/D convert the signal, through a specific sampling rate, and to filter said signal.
- the closed loop control (CLC) is enabled and its flag is set to 1 when the following conditions are met:
- the CLC mode is preferably disabled and its flag is set to 0 when one of the following conditions is met:
- TPS > CLCDeltaTPS (keep CLC disabled for a certain time, for example 3 sec, and then check again)
- TPS 0 and RPM > of a preset threshold (ThresHoldRPM) , which represents a required cut-off condition
- the RPM (revolution per minute) and Temperature threshold values are defined with a certain tolerance margin (hysteresis) , for example 5°C for temperature and 300rpm for RPMs.
- tolerance margin for example 5°C for temperature and 300rpm for RPMs.
- the calibration parameters (as described above) to be used in the control strategy of the carburettor electrovalve sole ⁇ noid, based on the values transmitted by the 0 2 sensor, are to be assessed also based on the experimental results of the spe- cific system.
- the system is affected by a series of typical reaction times, which are typically a) closed loop behaviour of the electrovalve due to its P M period; b) physical delay between electrovalve air metering, mixture preparation, intake port transportation, in-cylinder processing and exhaust port transportation; c) 0 2 sensor response time. All these typical times are also linked to the specific system ther ⁇ modynamics ' and can hence be taken into account, acting on a series of calibration parameters determined experimentally in the real application.
- the correction introduced on the basis of the value received by the oxygen probe can be applied preferably every two (or more) engine cycles.
- the CLC strategy is enabled while the engine is running (i.e. key-on and engine speed is detected and is above the cranking threshold) and an assigned time has elapsed.
- the latter is defined by the calibration constant CLCEnRevN.
- the CLCTPSEnLo, CLCTPSEnHi and CLCDeltaTPS are calibration parameters used for the throttle thresholds of the CLC working range. Thereby the CLC is not active in the presence of an aggressive driving style - as detected by the throttle position sensor (TPS) , i.e. at high loads or during sudden acceleration. In order to improve drivability, a hysteresis range is provided, by adopting different High (Hi) and Low (Lo) threshold values.
- 02ReadyHigh and 02ReadyLow are two fixed calibration parameters (with a defined sensor these two values will be fixed) that enable lambda sensor use.
- the 0 2 sensor output is greater than 02ReadyHigh, or lower than 02ReadyLow values, the 0 2 sensor is considered ready for working for the closed loop control . Then the 02 sensor is ready and its status flag 02Ready is set to 1. On the other hand, whenever the 0 2 sensor voltage lies outside of the above mentioned threshold, the 02 Ready flag is set to 0.
- Combustion is considered rich if the output from the 0 2 sensor is above rich voltage (Rich02Threshold) .
- Combustion is considered lean if the output from the oxygen sensor (lambda voltage) falls below 0 2 lean voltage (Lean02Threshold) .
- supe- rior results can be obtained when the closed loop control factor is calculated with a control technique having a jump and ramp between rich and lean condition.
- This technique involves determining two operating parameters: a first, relatively high, step term (StepL, StepR) to be used for the jump portion, and a second, lower, increment term (IncrL, IncrR) to be used in the ramp portion.
- StepL, StepR step term
- IncrL, IncrR increment term
- the voltage value of the oxygen probe (02State) is read upon each control cycle CLCStepCycle (which is a calibration constant, equal to or multiple of an engine cycle) and, based on the two switching conditions the simplified probe can take on: If: 02State changes from Rich to Lean
- the CLC factor is set equal to 0.
- the actual step and increment term values to be applied shall be interpolated from the maps .
- stepR stepL (i.e the same values on the lean or rich side of the control)
- deltaStepR deltaStepL
- the CLC compensation value must remain within the range of
- MaxCLC and MinCLC are calibration parameters . When the calculated CLC is above or below the specified range, the CLC factor is assumed to be equal to MaxCLC or MinCLC, respectively.
- the system employes a carburettor with pilot circuit setting screw
- EOL End Of Line
- Improper setting of this screw may result in lambda control troubles or inefficiency.
- the above mentioned setting screw shall have a stroke limiter, like i.e. +/- 1 ⁇ 2 turn, or a anti-tampering cap.
- the pilot screw has to be set on the engine and/or on the carburettor production line, while measuring the pilot circuit flow.
- the electrovalve driving the A/F ratio on the carburettor, acting on the air bypass conduit, is controlled with the PWM technique.
- the PWM control calculated in a conventional way (PWM base), for example as shown in EP1835154, is corrected by the CLC factor and, if used, AL (Auto Learning) factor, as follows:
- the PWM factor can be managed also in the non- linear ranges of 0-15% and 85-100%, which range in the conventional control (i.e. without closed loop control) had instead to be cut .
- the actual driving PWM sent to the so- lenoid valve of the carburettor must be kept at 0 or 100%, respectively.
- control electrovalve Since the control electrovalve is placed on the pilot circuit, its AFR (air/fuel ratio) variation potential could be limited in some working conditions. In these cases, the electro- valve is driven by the correction factor to remain fully closed whenever the AFR is lean, or completely open whenever the AFR is rich, even if the stoichiometric condition cannot be approached.
- the calibration parameters of the closed loop control are set in order to bias the AFR value on the lean or rich side of the stoichiometric condition.
- the calibration parameters are set so that the operation conditions are offset compared to the stoichiometric conditions . This has the advantage that better results in terms of maximizing catalytic reduction of NOx or CO e HC cab be obtained.
- the closed loop control may be further enhanced by using a self-teaching strategy.
- Fig. 5 compared with fig. 4, shows clearly that the A/F value can be kept more regular and constant with the system according to the invention.
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
- Combined Controls Of Internal Combustion Engines (AREA)
Abstract
Système et procédé de commande électronique pour moteurs à combustion interne à carburateur. Le système comprend une unité de commande conçu pour commander au moins une électrovanne pour le réglage de l'air d'émulsion du carburateur, lequel mélange détermine le rapport air-carburant (limiteur d'injection/AFR) du mélange de carburant, ainsi qu'une sonde d'O2 mono-fil permettant de déterminer la composition des gaz d'échappement et d'envoyer un signal sur la teneur en O2 à ladite unité de commande. Ladite sonde d'O2 commute entre deux états de O2 (seuil mélange pauvre en O2, seuil mélange riche en O2) et la commande de l'électrovanne pour le réglage du carburateur est du type à bouche fermée sur la base des deux états de O2.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
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PCT/IT2010/000148 WO2011125079A1 (fr) | 2010-04-09 | 2010-04-09 | Système et procédé de commande de moteurs à carburateur équipés d'une sonde lambda |
Applications Claiming Priority (1)
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PCT/IT2010/000148 WO2011125079A1 (fr) | 2010-04-09 | 2010-04-09 | Système et procédé de commande de moteurs à carburateur équipés d'une sonde lambda |
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WO2011125079A1 true WO2011125079A1 (fr) | 2011-10-13 |
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Citations (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3759232A (en) | 1972-01-29 | 1973-09-18 | Bosch Gmbh Robert | Method and apparatus to remove polluting components from the exhaust gases of internal combustion engines |
US4122811A (en) * | 1977-07-25 | 1978-10-31 | General Motors Corporation | Digital closed loop fuel control system |
GB2022295A (en) * | 1978-06-02 | 1979-12-12 | Hitachi Ltd | Electronic fuel control system for an internal combustion engine |
US4461258A (en) * | 1980-10-18 | 1984-07-24 | Robert Bosch Gmbh | Regulating device for a fuel metering system of an internal combustion engine |
DE4210814A1 (de) * | 1992-04-01 | 1993-10-07 | Hjs Fahrzeugteile Gmbh | Brennkraftmaschine |
US5460149A (en) * | 1993-02-10 | 1995-10-24 | Tofel; Richard M. | Carburetor kit for improved air-fuel mixture |
US5575268A (en) | 1994-11-24 | 1996-11-19 | Kabushiki Kaisha Keihinseiki Seisakusho | Air-fuel ratio controlling system for internal combustion engine |
EP1835154A1 (fr) | 2006-03-16 | 2007-09-19 | Dell'orto S.P.A. | Contrôle électronique, système pour moteurs à carburateur, à allumage commandé, et à combustion interne |
-
2010
- 2010-04-09 WO PCT/IT2010/000148 patent/WO2011125079A1/fr active Application Filing
Patent Citations (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3759232A (en) | 1972-01-29 | 1973-09-18 | Bosch Gmbh Robert | Method and apparatus to remove polluting components from the exhaust gases of internal combustion engines |
US4122811A (en) * | 1977-07-25 | 1978-10-31 | General Motors Corporation | Digital closed loop fuel control system |
GB2022295A (en) * | 1978-06-02 | 1979-12-12 | Hitachi Ltd | Electronic fuel control system for an internal combustion engine |
US4461258A (en) * | 1980-10-18 | 1984-07-24 | Robert Bosch Gmbh | Regulating device for a fuel metering system of an internal combustion engine |
DE4210814A1 (de) * | 1992-04-01 | 1993-10-07 | Hjs Fahrzeugteile Gmbh | Brennkraftmaschine |
US5460149A (en) * | 1993-02-10 | 1995-10-24 | Tofel; Richard M. | Carburetor kit for improved air-fuel mixture |
US5575268A (en) | 1994-11-24 | 1996-11-19 | Kabushiki Kaisha Keihinseiki Seisakusho | Air-fuel ratio controlling system for internal combustion engine |
EP1835154A1 (fr) | 2006-03-16 | 2007-09-19 | Dell'orto S.P.A. | Contrôle électronique, système pour moteurs à carburateur, à allumage commandé, et à combustion interne |
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