Classifications

• • 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
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D41/00—Electrical control of supply of combustible mixture or its constituents
  • F02D41/02—Circuit arrangements for generating control signals
  • F02D41/14—Introducing closed-loop corrections
  • F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
  • F02D41/1444—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases
  • F02D41/1446—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being exhaust temperatures
• • 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
  • F02D2041/0265—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus to decrease temperature of the exhaust gas treating apparatus
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D2200/00—Input parameters for engine control
  • F02D2200/02—Input parameters for engine control the parameters being related to the engine
  • F02D2200/08—Exhaust gas treatment apparatus parameters
  • F02D2200/0802—Temperature of the exhaust gas treatment apparatus
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D2200/00—Input parameters for engine control
  • F02D2200/02—Input parameters for engine control the parameters being related to the engine
  • F02D2200/10—Parameters related to the engine output, e.g. engine torque or engine speed
  • F02D2200/1002—Output torque

Definitions

• the invention relates to a method for controlling the richness of the air-fuel mixture in an internal combustion engine of the spark ignition type (operating in particular with gasoline). It finds an advantageous application in the automotive field.
• the air-fuel mixture is generally enriched, for example at values of richness which may be greater than 1, 20, when it is detected that a value of torque (or load) above a predetermined threshold is required for driving the vehicle.
• the value of richness to be adjusted to obtain a given maximum exhaust temperature for example a given exhaust manifold temperature value or a temperature value of a given turbocharger turbine (in the case of a supercharged engine ), can be determined by prior tests performed on the engine bench in stabilized mode, that is to say, by maintaining constant speed and torque.
• the value of the richness is regulated so that the temperature of the exhaust gas itself is equal to a given predetermined value, this value becoming that of the components of the exhaust system of the engine after a certain lapse of time which is related to the inertia of matter.
• the publication JP-S-6043144 discloses a method of adjusting the fuel injection time, according to the operating conditions of an engine, which is intended to prevent the exhaust system from overheating.
• a temperature sensor measures the temperature of the exhaust gas, and the richness is increased after a predetermined delay time which is a decreasing function of said gas temperature.
• the delay is to avoid unnecessary fuel consumption. Indeed, it is not necessary to increase the wealth immediately as soon as a high load is detected, because the parts that make up the exhaust system have a certain heat capacity and are therefore not instantly brought to temperatures below 20 ° C. limits for their reliability by the heat coming from the exhaust gases when the engine is running at high load. This property can thus be used to delay the increase in wealth without jeopardizing the reliability of the engine, which in principle saves fuel.
• this method is imprecise because the temperature measured by the sensor after the detection of a high load does not correctly represent the temperature of the parts of the engine exhaust circuit at the same time. More specifically, the temperature of the parts depends on the amount of heat that has been supplied to said parts before the high load is detected, and it is all the higher a high amount of heat energy has been supplied to said parts.
• a high reference load (designated by the acronym PMOTP1), which is used to determine if the exhaust system parts are in high load thermal conditions. If the test is positive, it indicates that the temperature of the parts increases because of the heat coming from the exhaust gases, and that the parts can be brought to overheat in the absence of an increase of the richness.
• a delay counter (designated by the acronym COTPCY) is regularly incremented, which represents the proportions in which the temperature of the parts of the exhaust circuit has been high, because of the heat of the gases, before the detection of the high load, and comparing the value of said counter with a reference delay threshold (designated by the acronym QAOTP), which is pre-calibrated according to the air flow in the engine.
• the delay threshold is a decreasing function of the flow rate.
• the value of the meter is below the threshold, it is considered that the parts of the exhaust circuit will not overheat in the very near future, and no enrichment measurement is implemented.
• the value of the counter is greater than the threshold, the value of the counter is fixed on the value which it takes at the precise moment when the threshold is exceeded, and one immediately increases the wealth.
• Such a method requires an important work of pre-calibration of the delay thresholds.
• only the air flow in the motor is taken into account to fix them.
• the inaccuracies on the selected thresholds result either in a risk of Exceeding the permissible temperature (if the threshold is too high, leading to an enrichment that is too late), or fuel consumption too high (case of too low a threshold, which leads to an enrichment too early).
• US-A-4400944 discloses a method of adjusting the wealth which aims to prevent thermal malfunctions of the turbocharger of an engine, particularly at high speed and high load where the engine is adjusted with a feedrate to the engine. ignition very delayed, which promotes high temperatures of the turbocharger.
• the richness is set in open loop, adding a correction of fuel injection time at the injection time corresponding to a stoichiometric mixture, the correction being a function of the difference between the temperature and the temperature target.
• the richness is adjusted by subtracting a fuel injection time correction at the corresponding injection time to the stoichiometric mixture.
• Such a method in which the richness is variable, makes it possible to control the temperature of the exhaust gases on a target value, and does not require any work of choice of a delay time to increase the wealth to a value greater than 1. But it includes phases in which the target is exceeded, which can lead to loss of reliability of the components of the exhaust system, overconsumption of fuel and an increase in pollutant emissions of the engine.
• the invention proposes to remedy the defects of the known methods of adjusting the richness.
• the method is characterized in that it comprises, when said torque is greater than said torque threshold:
• FIG. 1 represents an example of a spark ignition internal combustion engine capable of implementing the method according to the invention.
• FIG. 2 is a flowchart of the steps of the wealth adjustment method according to one embodiment of the invention.
• FIG. 1 shows an internal combustion engine of the type shown in FIG. controlled ignition (operating in particular with gasoline), more specifically a section of a cylinder 1 of the engine block.
• An intake circuit 2 and an exhaust circuit 3 communicate respectively with an intake duct 4 and an exhaust duct 5 of the cylinder 1.
• the intake circuit 2 comprises, in a nonlimiting manner, from upstream to downstream in the direction of air circulation, the compressor 6 of a turbocharger 7 of the supercharger of the engine, an air flow control valve 8 , or throttle body 8, and an intake manifold 9, or distributor 9.
• the engine is non-limiting in the form of an indirect injection engine: a fuel injector 10 opens into the intake duct 4 so as to inject gasoline into said duct 4.
• the engine can be direct injection type.
• the cylinder 1 is capped by a cylinder head 11 of the engine.
• the cylinder head 11 houses an intake valve 12 which serves to open and close the intake duct 4 and an exhaust valve 13 which serves to open and close the exhaust duct 5.
• the cylinder 1 encloses a piston 14 adapted to move within a bore 15 of the cylinder 1 alternatively between a position of bottom dead center (PMB) and top dead center (TDC), and a combustion chamber 16 is formed in the defined space between the piston 14 and the cylinder head 11.
• a spark plug 17 is mounted on the cylinder head 11, the electrodes of which open into the combustion chamber 16.
• the exhaust circuit 3 includes, in a non-limiting manner, from upstream to downstream in the direction of circulation of the combustion gases, an exhaust manifold 18, the turbine 19 of the turbocharger 7, which is mounted on a shaft 20 common to the engine. compressor 6 and the turbine, and a device 21 for cleaning the combustion gases of the engine, for example a three-way catalyst 21.
• a temperature sensor 22 is mounted in the exhaust circuit 3 at the inlet of the turbine 19. It is able to measure the value of the temperature of the exhaust gas upstream of the turbine.
• a richness sensor 23, or oxygen sensor 23, is mounted in the exhaust circuit 3 of the engine, upstream of the three-way catalyst 21. It is able to measure the value of the oxygen concentration in the combustion gases of the engine. engine.
• an engine calculator (not shown) comprises means capable of determining at least one load value (or airflow) Qair, a value of injected fuel flow Qcarb and of the flow rate phasing. fuel with respect to the top dead center, as well as a value of ignition advance AA according to a set of parameters representative of the operation of the engine, comprising at least the torque C and the engine speed N.
• the computer adjusts the Qair load by adjusting the degree of opening of the throttle body 8 and / or the power of the turbine via the degree of opening of a discharge valve to the exhaust of the turbine, also called waste-gate valve (not shown). It regulates the fuel flow Qcarb and the timing of its injection by adjusting the injection time Ti of the injector 10, more precisely the opening start time and the opening end instant, relative to the top dead center. It adjusts the advance ignition AA by sparking a spark across the electrodes of the spark plug 17 at a given angle of the engine cycle relative to the top dead center of the cylinder 1.
• a wealth control method may comprise the following steps, implemented by the engine computer and performed iteratively at each instant t n + i separated from the previous instant t n by a step of time dt constant:
• the process begins with a step 100 during which the engine computer determines a value of engine speed N and torque setpoint C required for driving the vehicle.
• the speed value can come from a sensor (not shown in FIG. 1) mounted at the end of the crankshaft of the engine, and the value of torque can be deduced from the value of the depression of the acceleration pedal of the vehicle by the driver.
• the motor torque is close to full load or not.
• the torque C is between a torque threshold Cs which is less than or equal to the maximum torque Cmax that can develop the engine, and the maximum torque Cmax.
• the torque threshold Cs and the maximum torque Cmax depend on the speed N. They delimit a range of operating points in which, if the richness r of the air-fuel mixture was equal to 1, the temperature ⁇ ech of the combustion gases of the engine in upstream of the turbine (measured by the sensor 22) would be greater than a threshold that corresponds to a reliability limit (typically a temperature of the order of 950 ° C to 980 ° C).
• step 300 the richness r of the air - fuel mixture is set around the stoichiometric richness (richness 1), then it resumes in step 100.
• the process points to a step 400 in which the richness r is set to a first richness value r 1 corresponding to a slightly rich mixture, for example a richness of between 1.00 and 1.05.
• the first value of richness is substantially equal to 1, 01, so as to allow immediate pre-cooling of the engine exhaust without significantly degrading the emissions of nitrogen oxides of the vehicle, and the wealth is set immediately to this first richness value equal to 1.01.
• the first value of richness may be substantially equal to 1.05, the adjustment of the richness at this first value of richness being carried out progressively, for example in a linear manner as a function of time from the stoichiometric value up to said first richness value substantially equal to 1.05.
• step 500 in which the temperature of the exhaust gas ⁇ ech is measured, for example by means of the temperature sensor 22.
• the order of the steps 400 and 500 can be reversed.
• said temperature ⁇ ech is compared with a first temperature threshold ⁇ 1 , for example a temperature of the order of 900 ° C. If said temperature is lower than said first threshold, the process resumes at step 100. In other words, the richness remains set to the stoichiometric value.
• a second temperature threshold ⁇ 2 for example of the order of 950 ° C. at 980 ° C, and corresponding to the thermomechanical resistance limit of the exhaust circuit. The method proposes not to exceed this second temperature threshold ⁇ 2.
• the process is directed to a step 800 in which the wealth is immediately set to a second value of compositer 2 .
• This second value of shieldr 2 is greater than the first value of richness n. It is determined so as to obtain a given maximum temperature of the parts making up the exhaust circuit, for example a given exhaust manifold temperature value or a temperature value of a given turbocharger turbine (in the case of a supercharged engine).
• the second value of richness r 2 can be determined by prior tests carried out on the engine bench in stabilized mode, that is to say by keeping the speed and the torque constant.
• step 900 in which the richness is increased progressively, that is to say by successive iterations to each time step dt each time the temperature of the exhaust gas is between the first and the second threshold 81, 82, from the first value of richness n to the maximum of the second value of richness r 2 .
• the ratio is increased linearly over time, while being limited by a maximum value equal to the second ratio value r 2, that is to say according to an equation of the type
• k denotes a positive constant coefficient, which is representative of the rate of increase of the richness.
• step 800 or step 900 the method then resumes in step 100. It is understood from the foregoing, and more particularly from the succession of steps 600 to 900, that when the motor enters under conditions close to full load, the temperature of the exhaust gas starts to increase continuously towards values which are approaching more and more the second temperature threshold 82. As soon as the temperature reaches the first temperature threshold 81, which can be considered as a warning threshold, we begin to increase the wealth. No delay time is applied, but the resources used are all less than the second wealth value r 2 which corresponds to the limit thermomechanical exhaust system.
• the method provisionally provides for an immediate increase in the temperature.
• richness r up to this second value of richness which instantly prevents the temperature of the exhaust gas from increasing even more and does not allow the temperature of the parts making up the exhaust circuit to exceed the second temperature threshold ⁇ 2, which makes it possible to guarantee their reliability.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Combined Controls Of Internal Combustion Engines (AREA)
• Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
• Electrical Control Of Ignition Timing (AREA)
• Supercharger (AREA)

Priority Applications (5)

Applications Claiming Priority (2)

Publications (1)

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ID=59521141

Family Applications (1)

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Cited By (1)

Citations (11)

Family Cites Families (9)

• 2017
  • 2017-03-16 FR FR1770257A patent/FR3064030B1/fr active Active
• 2018
  • 2018-03-09 EP EP18713325.1A patent/EP3596326B1/de active Active
  • 2018-03-09 JP JP2019550691A patent/JP2020510160A/ja active Pending
  • 2018-03-09 KR KR1020197029096A patent/KR20190126362A/ko not_active Application Discontinuation
  • 2018-03-09 WO PCT/FR2018/050558 patent/WO2018167406A1/fr unknown
  • 2018-03-09 RU RU2019132476A patent/RU2752657C2/ru active
• 2023
  • 2023-09-20 JP JP2023153685A patent/JP2023182629A/ja active Pending

Patent Citations (11)

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