EP1529941B1 - Procédé d'estimation de quantité de NOx générée dans un moteur à combustion interne - Google Patents

Procédé d'estimation de quantité de NOx générée dans un moteur à combustion interne Download PDF

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Publication number
EP1529941B1
EP1529941B1 EP04024927A EP04024927A EP1529941B1 EP 1529941 B1 EP1529941 B1 EP 1529941B1 EP 04024927 A EP04024927 A EP 04024927A EP 04024927 A EP04024927 A EP 04024927A EP 1529941 B1 EP1529941 B1 EP 1529941B1
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Prior art keywords
combustion
generated
fuel injection
region
gas
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German (de)
English (en)
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EP1529941A3 (fr
EP1529941A2 (fr
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Teruhiko Miyake
Shigeki Nakayama
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Toyota Motor Corp
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Toyota Motor Corp
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    • 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
    • F02D41/146—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being an NOx content or concentration
    • F02D41/1461—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being an NOx content or concentration of the exhaust gases emitted by the engine
    • F02D41/1462—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being an NOx content or concentration of the exhaust gases emitted by the engine with determination means using an estimation
    • 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
    • F02D35/02—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for on interior conditions
    • F02D35/025—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for on interior conditions by determining temperatures inside the cylinder, e.g. combustion temperatures
    • F02D35/026—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for on interior conditions by determining temperatures inside the cylinder, e.g. combustion temperatures using an estimation
    • 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
    • F02D41/04—Introducing corrections for particular operating conditions
    • F02D41/047—Taking into account fuel evaporation or wall wetting
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/14—Introducing closed-loop corrections
    • F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
    • F02D41/1439—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the position of the sensor
    • F02D41/144—Sensor in intake manifold
    • 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
    • F02D41/1401—Introducing closed-loop corrections characterised by the control or regulation method
    • F02D2041/1433—Introducing closed-loop corrections characterised by the control or regulation method using a model or simulation of the system
    • 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
    • F02D35/02—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for on interior conditions
    • 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
    • F02D41/0025—Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
    • F02D41/0047—Controlling exhaust gas recirculation [EGR]
    • F02D41/0065—Specific aspects of external EGR control
    • F02D41/0072—Estimating, calculating or determining the EGR rate, amount or flow

Definitions

  • the present invention relates to an NO x generation quantity estimation method for estimating the quantity of NO x which is generated in a combustion chamber of an internal combustion engine as a result of combustion of gas mixture containing fuel and air (the quantity of NO x generated in such a manner will be called "combustion-generated NO x quantity").
  • NO x discharge quantity the quantity of NO x contained in exhaust gas discharged from an exhaust passage to the outside
  • NO x discharge quantity the quantity of NO x contained in exhaust gas discharged from an exhaust passage to the outside
  • combustion-generated NO x quantity i.e., the quantity of NO x which is generated in a combustion chamber as a result of combustion of gas mixture atomized through injection and containing fuel and air.
  • An effective way of reducing the combustion-generated NO x quantity is lowering the highest flame temperature (highest combustion temperature) through, for example, increasing the quantity of EGR gas circulated by means of an EGR apparatus, or delaying fuel injection timing.
  • the combustion-generated NO x quantity is desirably controlled to a predetermined target value corresponding to the operating conditions of the engine. Meanwhile, direct measurement of the combustion-generated NO x quantity is considerably difficult. Therefore, in order to accurately control the combustion-generated NO x quantity to a predetermined target value, the combustion-generated NO x quantity must be accurately estimated.
  • a control apparatus for an internal combustion engine disclosed in Japanese Patent Application Laid-Open ( kokai ) No. 2002-371893 detects combustion pressure and intake-gas oxygen concentration by use of a cylinder pressure sensor and an intake-gas oxygen concentration sensor, and estimates the above-mentioned combustion-generated NO x quantity on the basis of combustion temperature and gas mixture concentration calculated on the basis of the combustion pressure and the intake-gas oxygen concentration, wherein the estimation is performed by use of the extended Zeldovich mechanism, which is a typical known combustion model. Then, EGR gas quantity, fuel injection timing, or the like is controlled so that the estimated combustion-generated NO x quantity coincides with the predetermined target value.
  • the actual quantity of NO x generated in a combustion chamber as a result of combustion of gas mixture greatly depends on peripheral condition quantities in relation to gas mixture, such as load exerted on the engine (drive torque) and the atomization level of fuel which constitutes gas mixture to be combusted.
  • the above-mentioned conventional apparatus does not take such peripheral condition quantities in relation to gas mixture into consideration for estimation of the combustion-generated NO x quantity. Therefore, the conventional apparatus has a drawback in that the above-mentioned combustion-generated NO x quantity cannot be accurately estimated, and thus, the above-mentioned (actual) combustion-generated NO x quantity cannot be accurately controlled to a predetermined target value.
  • an object of the present invention is to provide an NO x generation quantity estimation method for estimating combustion-generated NO x quantity; i.e., the quantity of NO x which is generated in a combustion chamber of an internal combustion engine as a result of combustion of gas mixture containing fuel and air, in consideration of peripheral condition quantities in relation to the gas mixture.
  • the present invention provides an NO x generation quantity estimation method for an internal combustion engine which estimates the above-mentioned combustion-generated NO x quantity on the basis of a peripheral condition quantity in relation to gas mixture which affects the combustion-generated NO x quantity. Since the combustion-generated NO x quantity can be estimated in consideration of a peripheral condition quantity in relation to gas mixture which affects the combustion-generated NO x quantity, the combustion-generated NO x quantity can be accurately estimated.
  • the combustion-generated NO x quantity is preferably estimated on the basis of at least a load index value which represents the degree of load of the engine and serves as the peripheral condition quantity.
  • the load index value which represents the degree of load of the engine, include fuel injection quantity (per operation cycle), drive torque of the engine, and temperature of the inner wall surface of a combustion chamber.
  • the combustion-generated NO x quantity can be estimated in such a manner that the combustion-generated NO x quantity increases with the load represented by the load index value. As a result, the combustion-generated NO x quantity can be accurately estimated.
  • the combustion-generated NO x quantity is preferably estimated on the basis of at least an atomization index value which represents the degree of atomization of (injected) fuel within the combustion chamber and serves as the peripheral condition quantity.
  • the atomization index value which represents the degree of atomization of fuel within the combustion chamber, include fuel injection pressure, swirl ratio, and excess air ratio in a region where combustion occurs.
  • the present invention also provides an NO x discharge quantity estimation method for an internal combustion engine in which the quantity of NO x contained in exhaust gas discharged from the exhaust passage of the engine to the outside (hereinafter referred to as "NO x discharge quantity”) is estimated by use of the above-described NO x generation quantity estimation method of the present invention.
  • the NO x discharge quantity estimation method comprises the steps of: estimating a combustion region, the combustion region being a portion of the combustion chamber in which combustion of the gas mixture occurs; estimating, by use of the NO x generation quantity estimation method of the present invention, a quantity of NO x generated in the combustion region as a result of the combustion of the gas mixture; estimating a quantity of NO x in a non-combustion region, the non-combustion region being the remaining portion of the combustion chamber; and estimating the NO x discharge quantity on the basis of the combustion-generated NO x quantity and the quantity of NO x in the non-combustion region.
  • the above-mentioned combustion-generated NO x quantity is the quantity of NO x generated in the region (the above-mentioned combustion region) which is a portion of the combustion chamber and in which combustion occurs. Accordingly, in the remaining portion of the combustion chamber (hereinafter referred to as the "non-combustion region"), the circulated NO x remains even after combustion. Therefore, in order to accurately estimate the quantity of NO x contained in exhaust gas discharged from the exhaust passage to the outside, not only the combustion-generated NO x quantity but also the "quantity of NO x remaining in the non-combustion region" must be taken into consideration.
  • the NO x discharge quantity is estimated in consideration of not only the quantity of NO x generated in the estimated combustion region as a result of combustion but also the quantity of NO x in the non-combustion region (after combustion); i.e., the above-mentioned "quantity of NO x remaining in the non-combustion region.”
  • the NO x discharge quantity can be accurately estimated.
  • FIG. 1 schematically shows the entire configuration of a system in which such an engine control apparatus is applied to a four-cylinder internal combustion engine (diesel engine) 10.
  • This system comprises an engine main body 20 including a fuel supply system; an intake system 30 for introducing gas to combustion chambers (cylinder interiors) of individual cylinders of the engine main body 20; an exhaust system 40 for discharging exhaust gas from the engine main body 20; an EGR apparatus 50 for performing exhaust circulation; and an electronic control apparatus 60.
  • Fuel injection valves (injection valves, injectors) 21 are disposed above the individual cylinders of the engine main body 20.
  • the fuel injection valves 21 are connected via a fuel line 23 to a fuel injection pump 22 connected to an unillustrated fuel tank.
  • the fuel injection pump 22 is electrically connected to the electronic control apparatus 60.
  • the fuel injection pump 22 pressurizes fuel in such a manner that the actual injection pressure (discharge pressure) of fuel becomes equal to the instruction base fuel injection pressure Pcrbase.
  • each of the fuel injection valves 21 opens for a predetermined period of time so as to inject, directly to the combustion chamber of the corresponding cylinder, the fuel pressurized to the instruction base fuel injection pressure Pcrbase, in the instruction fuel injection quantity qfin.
  • the intake system 30 includes an intake manifold 31, which is connected to the respective combustion chambers of the individual cylinders of the engine main body 20; an intake pipe 32, which is connected to an upstream-side branching portion of the intake manifold 31 and constitutes an intake passage in cooperation with the intake manifold 31; a throttle valve 33, which is rotatably held within the intake pipe 32; a throttle valve actuator 33a for rotating the throttle valve 33 in accordance with a drive signal from the electronic control apparatus 60; an intercooler 34, which is interposed in the intake pipe 32 to be located on the upstream side of the throttle valve 33; a compressor 35a of a turbocharger 35, which is interposed in the intake pipe 32 to be located on the upstream side of the intercooler 34; and an air cleaner 36, which is disposed at a distal end portion of the intake pipe 32.
  • the exhaust system 40 includes an exhaust manifold 41, which is connected to the individual cylinders of the engine main body 20; an exhaust pipe 42, which is connected to a downstream-side merging portion of the exhaust manifold 41; a turbine 35b of the turbocharger 35 interposed in the exhaust pipe 42; and a diesel particulate filter (hereinafter referred to as "DPNR") 43, which is interposed in the exhaust pipe 42.
  • the exhaust manifold 41 and the exhaust pipe 42 constitute an exhaust passage.
  • the DPNR 43 is a filter unit which accommodates a filter 43a formed of a porous material such as cordierite and which collects, by means of a porous surface, the particulate matter contained in exhaust gas passing through the filter.
  • a filter 43a formed of a porous material such as cordierite and which collects, by means of a porous surface, the particulate matter contained in exhaust gas passing through the filter.
  • the DPNR 43 also serves as a storage-reduction-type NO x catalyst unit which, after absorption of NO x , releases the absorbed NO x and reduces it.
  • the EGR apparatus 50 includes an exhaust circulation pipe 51, which forms a passage (EGR passage) for circulation of exhaust gas; an EGR control valve 52, which is interposed in the exhaust circulation pipe 51; and an EGR cooler 53.
  • the exhaust circulation pipe 51 establishes communication between an exhaust passage (the exhaust manifold 41) located on the upstream side of the turbine 35b, and an intake passage (the intake manifold 31) located on the downstream side of the throttle valve 33.
  • the EGR control valve 52 responds to a drive signal from the electronic control apparatus 60 so as to change the quantity of exhaust gas to be circulated (exhaust-gas circulation quantity, EGR-gas flow rate).
  • the electronic control apparatus 60 is a microcomputer which includes a CPU 61, ROM 62, RAM 63, backup RAM 64, an interface 65, etc., which are connected to one another by means of a bus.
  • the ROM 62 stores a program to be executed by the CPU 61, tables (lookup tables, maps), constants, etc.
  • the RAM 63 allows the CPU 61 to temporarily store data when necessary.
  • the backup RAM 64 stores data in a state in which the power supply is on, and holds the stored data even after the power supply is shut off.
  • the interface 65 contains A/D converters.
  • the interface 65 is connected to a hot-wire-type airflow meter 71, which serves as air flow rate (new air flow rate) measurement means, and is disposed in the intake pipe 32; an intake gas temperature sensor 72, which is provided in the intake passage to be located downstream of the throttle valve 33 and downstream of a point where the exhaust circulation pipe 51 is connected to the intake passage; an intake pipe pressure sensor 73, which is provided in the intake passage to be located downstream of the throttle valve 33 and downstream of the point where the exhaust circulation pipe 51 is connected to the intake passage; a crank position sensor 74; an accelerator opening sensor 75; and an intake-gas oxygen concentration sensor 76 provided in the intake passage to be located downstream of the throttle valve 33 and downstream of the point where the exhaust circulation pipe 51 is connected to the intake passage.
  • the interface 65 receives respective signals from these sensors, and supplies the received signals to the CPU 61. Further, the interface 65 is connected to the fuel injection valves 21, the fuel injection pump 22, the throttle valve actuator 33a, and the EGR control valve 52; and outputs corresponding drive signals to these components in accordance with instructions from the CPU 61.
  • the hot-wire-type airflow meter 71 measures the mass flow rate of intake air (new air) passing through the intake passage (intake new air quantity per unit time), and generates a signal indicating the mass flow rate Ga (intake new air flow rate Ga).
  • the intake gas temperature sensor 72 detects the temperature of the above-mentioned intake gas, and generates a signal representing the intake gas temperature Tb.
  • the intake pipe pressure sensor 73 measures the pressure of intake gas (i.e., intake pipe pressure), and generates a signal representing the intake pipe pressure Pb.
  • the crank position sensor 74 detects the absolute crank angle of each cylinder, and generates a signal representing the crank angle CA and engine speed NE; i.e., rotational speed of the engine 10.
  • the accelerator opening sensor 75 detects an amount by which an accelerator pedal AP is operated, and generates a signal representing the accelerator pedal operated amount Accp.
  • the intake-gas oxygen concentration sensor 76 detects the oxygen concentration of intake gas (i.e., intake-gas oxygen concentration), and a signal representing intake-gas oxygen concentration RO2_in.
  • FIG. 2 is a diagram schematically showing a state in which gas (intake gas) is taken from the intake manifold 31 into a certain cylinder (cylinder interior) of the engine 10 and is then discharged to the exhaust manifold 41.
  • intake gas (accordingly, cylinder interior gas) includes new air taken from the tip end of the intake pipe 32 via the throttle valve 33, and EGR gas (including NO x ) taken from the exhaust circulation pipe 51 via the EGR control valve 52.
  • the mass ratio i.e., EGR ratio
  • EGR ratio EGR ratio of the mass of the taken EGR gas (EGR gas mass) to the sum of the mass of the taken new air (new air mass) and the mass of the taken EGR gas (EGR gas mass) changes depending on the opening of the throttle valve 33 and the opening of the EGR control valve 52, which are properly controlled by the electronic control apparatus 60 (CPU 61) in accordance with the operating condition.
  • the intake gas i.e., gas composed of the new air and the EGR gas containing NO x
  • the intake valve Vin is taken in the cylinder via an opened intake valve Vin as the piston moves downward, and the thus-produced gas mixture serves as cylinder interior gas.
  • the cylinder interior gas is confined within the cylinder when the intake valve Vin closes upon the piston having reached bottom dead center (hereinafter referred to as "ATDC-180°"), and then compressed in a subsequent compression stroke as the piston moves upward.
  • the present apparatus opens the corresponding fuel injection valve 21 for a predetermined period of time corresponding to the instruction fuel injection quantity qfin, to thereby inject fuel directly into the cylinder.
  • the injected fuel disperses in the cylinder with elapse of time, while mixing with the cylinder interior gas to produce a gas mixture.
  • the gas mixture starts combustion by means of self ignition at a predetermined timing.
  • region B a combustion region
  • region A a non-combustion region
  • NO x generation quantity estimation method upon arrival of each time when the final fuel injection timing finjfin for a cylinder to which fuel is injected (hereinafter referred to as "fuel injection cylinder"), B-region combustion-generated NO x quantity NOxB (quantity of NO x generated as a result of combustion in the region B during the expansion stroke immediately after the final fuel injection timing) is estimated.
  • NOxB RNOx_burn ⁇ qfinc
  • RNOx_burn e K ⁇ 0 ⁇ RO ⁇ 2 ⁇ c K ⁇ 1 ⁇ qfinc K ⁇ 2 ⁇ Pcrc K ⁇ 3 ⁇ e K ⁇ 4 / Tflame
  • Eq. (2) e is the base of a natural logarithm.
  • RO2c is bottom-dead-center intake-gas oxygen concentration; i.e., intake-gas oxygen concentration RO2_in detected by means of the intake-gas oxygen concentration sensor 76 at the time when the intake valve Vin is closed (i.e., ATDC-180°).
  • Tflame is highest flame temperature in the expansion stroke of the present operation cycle.
  • the highest flame temperature Tflame is a peak value of flame temperature during a period between start of combustion of gas mixture and end of the combustion, and can be estimated on the basis of a predetermined function which uses, as arguments, engine speed NE and instruction fuel injection quantity qfinc in the present operation cycle.
  • K0 to K4 are fitting constants which are determined in the manner described below on the basis of typical known multiple regression analysis.
  • Eq. (2) is an empirical formula for obtaining the combustion-generated NO x ratio RNOx_burn.
  • the combustion-generated NO x ratio RNOx_burn estimated by Eq. (2) is a function of the bottom-dead-center intake-gas oxygen concentration RO2c, the instruction fuel injection quantity qfinc in the present operation cycle, the instruction fuel injection pressure Pcrc in the present operation cycle, and the highest flame temperature Tflame.
  • the combustion-generated NO x ratio RNOx_burn is calculated on the basis of the product of the power of the bottom-dead-center intake-gas oxygen concentration RO2c, the power of the instruction fuel injection quantity qfinc in the present operation cycle, the power of the instruction fuel injection pressure Pcrc in the present operation cycle, and an exponential function whose exponent is determined in accordance with the highest flame temperature Tflame.
  • the fitting constants K0 to K4 can be determined, for example, through performance of an experiment as follows. That is, first, the engine 10 is operated while the EGR control valve 52 is maintained closed, whereby all the exhaust gas (accordingly, NO x contained in the exhaust gas) discharged via the exhaust valve Vout is discharged to the outside from the exhaust passage.
  • the quantity of NO x contained in the exhaust gas discharged to the outside from the exhaust passage i.e., the above-mentioned NO x discharge quantity
  • the values of the bottom-dead-center intake-gas oxygen concentration RO2c, the instruction fuel injection quantity qfinc in the present operation cycle, the instruction fuel injection pressure Pcrc in the present operation cycle, and the highest flame temperature Tflame are successively changed so that combinations of the respective values are attained in various predetermined patterns.
  • the combustion-generated NO x ratio RNOx_burn is successively measured for each pattern.
  • the predetermined known multiple regression analysis is performed on the basis of a large number of data sets regarding the relationship between measured values of the combustion-generated NO x ratio RNOx_burn and the combinations of the above-mentioned respective values, which were obtained as a result of such a work (experiment), whereby the above-mentioned fitting constants K0 to K4 can be obtained.
  • the fitting constants K1 to K3 are determined to assume positive values
  • the fitting constants K4 is determined to assume a negative value.
  • the combustion-generated NO x ratio RNOx_burn (accordingly, B-region combustion-generated NO x quantity NOxB) calculated and estimated in accordance with Eq. (2) increases with an increase in any one of the bottom-dead-center intake-gas oxygen concentration R02c, the instruction fuel injection quantity qfinc in the present operation cycle, the instruction fuel injection pressure Pcrc in the present operation cycle, and the highest flame temperature Tflame. This matches the actual phenomena described below.
  • the B-region combustion-generated NO x quantity NOxB increases with the intake-gas oxygen concentration RO2_in. This phenomenon occurs because oxygen is a material for generation of NO x , and an increase in the quantity of oxygen within the combustion chamber naturally facilitates generation of NO x .
  • the B-region combustion-generated NO x quantity NOxB increases with the fuel injection quantity qfin. This phenomenon occurs as follows. When the fuel injection quantity qfin increases, the load of the engine 10 increases, so that the inner wall temperature of the combustion chamber increases. Therefore, the greater the fuel injection quantity qfin (i.e., the greater the load of the engine), the greater the quantity of NO x that is generated.
  • the B-region combustion-generated NO x quantity NOxB increases with the fuel injection pressure Pcr. This phenomenon occurs as follows. When the fuel injection pressure Pcr is increased, the injection speed of fuel increases with a resultant increase in the degree of atomization of the fuel, whereby the above-mentioned excess air factor increases. Therefore, the greater the fuel injection pressure Pcr (i.e., the greater the degree of atomization of injected fuel), the greater the quantity of NO x that is generated.
  • the B-region combustion-generated NO x quantity NOxB increases with the highest flame temperature Tflame. This phenomenon occurs because increased gas temperature accelerates a chemical reaction of producing NO x from nitrogen.
  • the combustion-generated NO x ratio RNOx_burn be accurately estimated (thus, the B-region combustion-generated NO x quantity NOxB can be accurately estimated in accordance with Eq. (1)) in such a manner that the estimated values follow at least the above-described four actual phenomena.
  • the above is the outline of the NO x generation quantity estimation method.
  • NO x discharge quantity estimation method upon each arrival of the final fuel injection timing finjfin for the fuel injection cylinder, the mass of NO x contained in exhaust gas (i.e., NO x discharge quantity, actual NO x discharge quantity NOxact) is estimated, the exhaust gas being discharged from the fuel injection cylinder to the outside via the exhaust valve Vout and the exhaust passage during the exhaust stroke immediately after the final fuel injection timing.
  • NO x quantity ratio RatioNOx the ratio of the mass of NO x present in the above-described region B before combustion to the total mass of NO x taken in the combustion chamber
  • oxygen quantity ratio represents the ratio of the volume of the region B to the volume of the combustion chamber, and also represents the ratio of the mass of NO x present in the region B before combustion to the total mass of NO x taken in the combustion chamber (accordingly, the above-mentioned NO x quantity ratio RatioNOx).
  • the region B can be estimated by use of the oxygen quantity ratio.
  • the oxygen quantity ratio is obtained in order to obtain the NO x quantity ratio RatioNOx, and the "total mass of oxygen taken in the combustion chamber" and the “mass of oxygen consumed by combustion” must be obtained in order to obtain the oxygen quantity ratio.
  • the “total mass of oxygen taken in the combustion chamber” can be obtained through multiplication of the total mass of gas taken in the combustion chamber (hereinafter referred to as "cylinder interior total gas quantity Gcyl”) by the oxygen concentration of the cylinder interior gas before combustion.
  • the cylinder interior total gas quantity Gcyl can be obtained in accordance with Eq. (3), which is based on the state equation of gas at ATDC-180°.
  • Gcyl Pa ⁇ 0 ⁇ Va ⁇ 0 / R ⁇ Ta ⁇ 0
  • Pa0 is bottom-dead-center cylinder interior gas pressure; i.e., cylinder interior gas pressure at ATDC-180°.
  • the cylinder interior gas pressure is considered to be substantially equal to the intake pipe pressure Pb. Therefore, the bottom-dead-center cylinder interior gas pressure Pa0 can be obtained from the intake pipe pressure Pb detected by means of the intake pipe pressure sensor 73 at ATDC-180°.
  • Va0 is bottom-dead-center combustion chamber volume; i.e., combustion chamber volume at ATDC-180°.
  • the combustion chamber volume Va can be represented as a function of the crank angle CA on the basis of the design specifications of the engine 10.
  • Ta0 is bottom-dead-center cylinder interior gas temperature; i.e., cylinder interior gas temperature at ATDC-180°.
  • the cylinder interior gas temperature is considered to be substantially equal to the intake gas temperature Tb. Therefore, the bottom-dead-center cylinder interior gas temperature Ta0 can be obtained from the intake gas temperature Tb detected by means of the intake gas temperature sensor 72 at ATDC-180°.
  • R is the gas constant of the cylinder interior gas.
  • the oxygen concentration of the cylinder interior gas before combustion can be considered to be substantially equal to the intake-gas oxygen concentration RO2_in at the time when the intake valve Vin is closed (i.e., at ATDC-180°). Therefore, the oxygen concentration of the cylinder interior gas before combustion can be obtained as the bottom-dead-center intake-gas oxygen concentration RO2c used in Eq. (2). From the above, the "total mass of oxygen taken in the combustion chamber" can be represented as "Gcyl ⁇ R02c.”
  • the "mass of oxygen consumed by combustion” can be represented as "K ⁇ qfinc" under the assumption that the entirety of injected fuel (i.e., fuel in the above-mentioned fuel injection quantity qfin) burns completely at the stoichiometric air-fuel ratio stoich.
  • K is a coefficient, which is a value obtained through multiplication of the mass ratio (0.23) of oxygen contained in the atmosphere by the stoichiometric air-fuel ratio stoich (e.g., 14.6); i.e., "0.23 stoich.”
  • the NO x quantity ratio RatioNOx can be obtained in accordance with the following Eq. (4).
  • RatioNOx K ⁇ qfinc / Gcyl ⁇ RO ⁇ 2 ⁇ c
  • A-region circulated NO x quantity NOxA the mass of NO x present within the region A before combustion
  • the ratio of the mass of NO x present within the region A before combustion to the total mass of NO x taken in the combustion chamber can be represented by use of the above-mentioned NO x quantity ratio RatioNOx; i.e., represented as "1 - RatioNOx.”
  • the A-region circulated NO x quantity NOxA can be obtained through multiplication of the cylinder interior total gas quantity Gcyl by the NO x concentration of the cylinder interior gas before combustion and (1 - RatioNOx).
  • NOxA RNOx_in ⁇ 1 - RatioNOx ⁇ Gcyl
  • the intake gas NO x concentration RNOx_in is the mass ratio of the mass of NO x contained in the EGR gas circulated from the EGR apparatus 50 to the cylinder interior total gas quantity Gcyl.
  • the intake gas NO x concentration RNOx_in can be obtained in accordance with the following Eq. (6).
  • RNOx_in RNOx_ex ⁇ Gegr / Gcyl
  • Gegr is the mass of EGR gas which has been taken, as a portion of intake gas, from the EGR apparatus 50 into the combustion chamber during the intake stroke of the present operation cycle, and can be obtained in accordance with the following Eq. (7).
  • Gegr Gcyl - Gm
  • Gm represents the mass (intake new air quantity) of new air which has been taken, as a portion of intake gas, from the tip end of the intake pipe 32 into the combustion chamber during the intake stroke of the present operation cycle, and is calculated on the basis of the intake new air quantity per unit time (intake new air flow rate Ga) measured by means of the airflow meter 71, the engine speed NE based on the output of the crank position sensor 74, and a function f(Ga, NE) which uses the intake new air flow rate Ga and the engine speed NE, as arguments, so as to obtain quantity of intake new air per intake stroke.
  • the A-region circulated NO x quantity NOxA, and thus the "mass of NO x remaining in the region A after combustion" can be obtained in accordance with the above-described Eq. (5).
  • the quantify of the generated NO x (the B-region combustion-generated NOx quantity NOxB) is estimated by the above-described Eqs. (1) and (2).
  • the thus-estimated B-region combustion-generated NO x quantity NOxB can be considered to be substantially equal to "the mass of NO x remaining in the region B after combustion.” Therefore, the "mass of NO x remaining in the region B after combustion" can be obtained as the B-region combustion-generated NO x quantity NOxB estimated in accordance with the above-described Eqs. (1) and (2).
  • the total mass of NO x remaining in the combustion chamber after combustion can be obtained as "NOxA + NOxB.”
  • the total mass of gas remaining in the combustion chamber after combustion can be obtained as "Gcyl + qfinc.”
  • the NO x concentration (exhaust gas NO x concentration RNOx_ex) of exhaust gas discharged from the combustion chamber to the exhaust passage (exhaust manifold 41) via the exhaust valve Vout during the exhaust stroke is equal to the mass ratio of the "total mass of NO x remaining in the combustion chamber after combustion" to the "total mass of gas remaining in the combustion chamber after combustion,” and can be obtained in accordance with the following Eq. (8).
  • RNOx_ex NOxA + NOxB / Gcyl + qfinc
  • the previous value of the exhaust gas NOx concentration RNOx_ex obtained in accordance with Eq. (8) is used in the above-described Eq. (6) for obtaining the intake gas NO x concentration RNOx_in, under the assumption that the NO x concentration of exhaust gas flowing through the exhaust passage (exhaust manifold 41) is equal to the NO x concentration of EGR gas flowing through the exhaust circulation pipe 51.
  • the exhaust gas NO x concentration RNOx_ex becomes equal to the NO x concentration of exhaust gas discharged to the outside from the exhaust passage (specifically, the end of exhaust pipe 42).
  • the mass per operation cycle (exhaust stroke) of exhaust gas which is discharged to the outside from the exhaust passage (exhaust pipe 42) is substantially equal to the above-mentioned intake new air quantity Gm.
  • the mass per operation cycle of NO x contained in exhaust gas which is discharged to the outside via the exhaust passage (the above-mentioned actual NO x discharge quantity NOxact) can be obtained in accordance with Eq. (9).
  • Eq. (9) shows that as the EGR gas quantity Gegr increases, the intake new air quantity Gm decreases, whereby the actual NO x discharge quantity NOxact decreases. Accordingly, the phenomenon that the actual NO x discharge quantity NOxact decreases as the EGR gas quantity Gegr increases can be accurately expressed.
  • NOxact RNOx_ex ⁇ Gm
  • the present apparatus estimates, by use of Eqs. (1) to (9), the actual NO x discharge quantity NOxact; i.e., the mass of NO x discharged from the fuel injection cylinder via the exhaust valve Vout in the exhaust stroke immediately after the injection timing.
  • the actual NO x discharge quantity NOxact i.e., the mass of NO x discharged from the fuel injection cylinder via the exhaust valve Vout in the exhaust stroke immediately after the injection timing.
  • the present apparatus which performs the above-mentioned NO x discharge quantity estimation method, calculates, at predetermined intervals, a target NO x discharge quantity per operation cycle NOxt on the basis of the above-mentioned fuel injection quantity qfin and engine speed NE. Subsequently, the present apparatus feedback-controls the final fuel injection start timing finjfin and the opening of the EGR control valve 52 in such a manner that the actual NO x discharge quantity NOxact estimated in the previous operation cycle coincides with the target NO x discharge quantity NOxt.
  • the final fuel injection start timing finjfin to be applied for the fuel injection cylinder in the present operation cycle is delayed from the base fuel injection start timing finjbase by a predetermined amount, and the opening of the EGR control valve 52 is increased from the current degree by a predetermined amount.
  • the highest flame temperature of the fuel injection cylinder in the present operation cycle is controlled to decrease, whereby the actual NO x discharge quantity NOxact; i.e., the quantity of NO x discharged from the fuel injection cylinder to the outside in the present operation cycle, is rendered coincident with the target NO x discharge quantity NOxt.
  • the final fuel injection start timing finjfin to be applied for the fuel injection cylinder in the present operation cycle is advanced from the base fuel injection start timing finjbase by a predetermined amount, and the opening of the EGR control valve 52 is decreased from the current degree by a predetermined amount.
  • the highest flame temperature of the fuel injection cylinder in the present operation cycle is controlled to increase, whereby the actual NO x discharge quantity NOxact; i.e., the quantity of NO x discharged from the fuel injection cylinder to the outside in the present operation cycle, is rendered coincident with the target NO x discharge quantity NOxt.
  • the above is the outline of fuel injection control.
  • log RNOx_burn K ⁇ 0 + dataMap ⁇ 1 + dataMap ⁇ 2 + dataMap ⁇ 3 + dataMap ⁇ 4
  • the present apparatus obtains the combustion-generated NO x Ratio RNOx_burn on the basis of a table Mapinvlog(log(RNOx_burn)), which is stored in the ROM 62 in order to obtain the combustion-generated NO x Ratio RNOx_burn from the "log(RNOx_burn)" obtained in accordance with Eq. (11).
  • This calculation procedure reduces the calculation load of the CPU 61 and prevents deterioration of calculation accuracy.
  • the CPU 61 repeatedly executes, at predetermined intervals, a routine shown by the flowchart of FIG. 3 and adapted to control fuel injection quantity, etc. Therefore, when a predetermined timing has been reached, the CPU 61 starts the processing from step 300, and then proceeds to step 305 so as to obtain an (instruction) fuel injection quantity qfin from an accelerator opening Accp, an engine speed NE, and a table (map) Mapqfin shown in FIG. 4 .
  • the table Mapqfin defines the relation between accelerator opening Accp and engine speed NE, and fuel injection quantity qfin; and is stored in the ROM 62.
  • the CPU 61 proceeds to step 310 so as to determine a base fuel injection timing finjbase from the fuel injection quantity qfin, the engine speed NE, and a table Mapfinjbase shown in FIG. 5 .
  • the table Mapfinjbase defines the relation between fuel injection quantity qfin and engine speed NE, and base fuel injection timing finjbase; and is stored in the ROM 62.
  • the CPU 61 proceeds to step 315 so as to determine a base fuel injection pressure Pcrbase from the fuel injection quantity qfin, the engine speed NE, and a table MapPcrbase shown in FIG. 6 .
  • the table MapPcrbase defines the relation between fuel injection quantity qfin and engine speed NE, and base fuel injection pressure Pcrbase; and is stored in the ROM 62.
  • the CPU 61 proceeds to step 320 so as to determine a target NO x discharge quantity NOxt from the fuel injection quantity qfin, the engine speed NE, and a table MapNOxt shown in FIG. 7 .
  • the table MapNOxt defines the relation between fuel injection quantity qfin and engine speed NE, and target NOx discharge quantity NOxt; and is stored in the ROM 62.
  • step 325 so as to store, as an NO x discharge quantity deviation ⁇ NOx, a value obtained through subtraction, from the target NO x discharge quantity NOxt, of the latest actual NO x discharge quantity NOxact, which is computed at a fuel injection timing in a previous operation cycle by a routine to be described later.
  • the CPU 61 proceeds to step 330 so as to determine an injection-timing correction value ⁇ from the NO x discharge quantity deviation ⁇ NOx and a table Map ⁇ shown in FIG. 8 .
  • the table Map ⁇ defines the relation between NOx discharge quantity deviation ⁇ NOx and injection-timing correction value ⁇ , and is stored in the ROM 62.
  • the CPU 61 proceeds to step 335 so as to correct the base fuel injection timing finjbase by the injection-timing correction value ⁇ to thereby obtain a final fuel injection timing finjfin.
  • the fuel injection timing is corrected in accordance with the NO x discharge quantity deviation ⁇ NOx.
  • the injection-timing correction value ⁇ becomes positive, and its magnitude increases with the magnitude of the NO x discharge quantity deviation ⁇ NOx, whereby the final fuel injection timing finjfin is shifted toward the advance side.
  • the injection-timing correction value ⁇ becomes negative, and its magnitude increases with the magnitude of the NO x discharge quantity deviation ⁇ NOx, whereby the final fuel injection timing finjfin is shifted toward the retard side.
  • step 340 determines whether the injection start timing (i.e., the final fuel injection timing finjfin) is reached for the fuel injection cylinder.
  • the CPU 61 makes a "No" determination in step 340, the CPU 61 proceeds directly to step 395 so as to end the current execution of the present routine.
  • step 345 so as to inject fuel in an amount of the (instruction) fuel injection quantity qfin into the fuel injection cylinder from the fuel injection valve 21 at the base fuel injection pressure Pcrbase.
  • step 355 the CPU 61 determines whether the NO x discharge quantity deviation ⁇ NOx is positive.
  • step 355 the CPU 61 proceeds to step 355 so as to reduce the opening of the EGR control valve 52 from the current degree by a predetermined amount. Subsequently, the CPU 61 proceeds to step 370.
  • step 360 determines whether the NO x discharge quantity deviation ⁇ NOx is negative.
  • step 365 so as to increase the opening of the EGR control valve 52 from the current degree by a predetermined amount.
  • step 370 the CPU 61 proceeds to step 370 without changing the opening of the EGR control valve 52.
  • step 370 the CPU 61 stores, as the fuel injection quantity qfinc in the present operation cycle, the fuel injection quantity qfin actually injected.
  • step 375 the CPU 61 stores, as the fuel injection pressure Pcrc in the present operation cycle, the base fuel injection pressure Pcrbase at which fuel was actually injected. Subsequently, the CPU 61 proceeds to step 395 so as to end the current execution of the present routine.
  • the CPU 61 repeatedly executes, at predetermined intervals, a routine shown by the flowcharts of FIG. 9 and adapted to calculate actual NO x discharge quantity NOxact. Therefore, when a predetermined timing has been reached, the CPU 61 starts the processing from step 900, and then proceeds to step 905 so as to determine whether the crank angle CA at the present point in time coincides with ATDC-180°.
  • step 935 so as to determine whether the fuel injection start timing (i.e., the final fuel injection timing finjfin) for the fuel injection cylinder has come. Since the crank angle CA at the present point in time has not yet reached ATDC-180°, the CPU 61 makes a "No" determination in step 935, and then proceeds directly to step 995 so as to end the current execution of the present routine.
  • the CPU 61 repeatedly performs the processing of steps 900, 905, 935, and 995 until the crank angle CA reaches ATDC-180°.
  • the CPU 61 makes a "Yes" determination when it proceeds to step 905, and then proceeds to step 910.
  • the CPU 61 stores, as bottom-dead-center cylinder interior gas temperature Ta0, bottom-dead-center cylinder interior gas pressure Pa0, bottom-dead-center intake new air flow rate Ga0, and bottom-dead-center engine speed NE0, respectively, the intake gas temperature Tb, the intake pipe pressure Pb, the intake new air flow rate Ga, and the engine speed NE, which are detected by means of the intake gas temperature sensor 72, the intake pipe pressure sensor 73, the airflow meter 71, and the crank position sensor 74, respectively, at the present point in time (ATDC-180°).
  • the CPU 61 proceeds to step 915 so as to store, as bottom-dead-center intake-gas oxygen concentration RO2c, the intake-gas oxygen concentration RO2_in detected by means of the intake-gas oxygen concentration sensor 76 at the present point in time (ATDC-180°).
  • the CPU 61 computes the cylinder interior total gas quantity Gcyl in accordance with the above-described Eq. (3).
  • the values stored at step 910 are employed as the bottom-dead-center cylinder interior gas pressure Pa0 and the bottom-dead-center cylinder interior gas temperature Ta0.
  • the CPU 61 proceeds to step 925 so as to compute an intake new air quantity Gm from the bottom-dead-center intake new air flow rate Ga0 and the bottom-dead-center engine speed NE0 in accordance with the above-defined function f.
  • the CPU 61 computes an EGR gas quantity Gegr on the basis of the cylinder interior total gas quantity Gcyl computed in step 920 and the intake new air quantity Gm, and in accordance with the above-described Eq. (7).
  • the CPU 61 proceeds to step 935 so as to make a "No" determination, and then proceeds to step 995 so as to end the current execution of the present routine.
  • the CPU 61 repeatedly performs the processing of steps 900, 905, 935, and 995 until the fuel injection timing (i.e., the final fuel injection timing finjfin) comes.
  • the CPU 61 makes a "Yes" determination in step 935 and then proceeds to step 940 so as to calculate the intake gas NO x concentration RNOx_in in accordance with the above-described Eq. (6).
  • the values computed in steps 930 and 920 are employed as the EGR gas quantity Gegr and the cylinder interior total gas quantity Gcyl, respectively.
  • the value which has been computed in step 965 (to be described later) at the fuel injection start timing in the previous operation cycle is employed as the exhaust gas NO x concentration RNOx_ex.
  • step 945 so as to compute an A-region circulated NO x quantity NOxA in accordance with the equation shown in step 945 of FIG. 9 ; the equation corresponding to the above-described Eqs. (4) and (5).
  • the latest value stored in step 370 of FIG. 3 is employed as the fuel injection quantity qfinc in the present operation cycle.
  • the CPU 61 proceeds via step 950 to step 1000 of FIG. 10 so as to start processing for computing a combustion-generated NO x ratio RNOx_burn.
  • the CPU 61 estimates and determines the highest flame temperature Tflame from the engine speed NE at the present point in time, the fuel injection quantity qfinc in the present operation cycle, and a table (shown in the step 1005 of FIG. 10 ) which is used for obtaining the highest flame temperature Tflame.
  • step 1030 the CPU 61 determines a combustion-generated NO x ratio RNOx_burn from the log(RNOx_burn) and the above-described table Mapinvlog, and then proceeds via step 1095 to step 955 of FIG. 9 .
  • step 955 the CPU 61 determines a B-region combustion-generated NO x quantity NOxB in accordance with the above-described Eq. (1). Subsequently, the CPU 61 proceeds to step 960 so as to determine an exhaust gas NO x concentration RNOx_ex in accordance with the above-described Eq. (8). In the subsequent step 965, the CPU 61 determines an actual NO x discharge quantity NOxact in accordance with the above-described Eq. (9), and then proceeds to step 995 so as to end the current execution of the present routine. After that, the CPU 61 repeatedly performs the processing of steps 900, 905, 935, and 995 until ATDC-180° for the fuel injection cylinder comes again.
  • a new latest actual NO x discharge quantity NOxact is obtained each time the fuel injection start timing comes.
  • the obtained new actual NO x discharge quantity NOxact is used in step 325 of FIG. 3 as described above.
  • the final fuel injection timing finjfin and the opening of the EGR control valve 52 to be applied to the fuel injection cylinder in the next operation cycle are feedback-controlled on the basis of the new actual NO x discharge quantity NOxact.
  • the NO x generation quantity estimation method for an internal combustion engine estimates B-region combustion-generated NO x quantity NOxB; i.e., the quantity of NO x generated in a combustion region (region B) as a result of combustion, on the basis of the following four peripheral condition quantities which largely affect the B-region combustion-generated NO x quantity NoxB: the concentration of a gas in intake gas serving as a raw material for generating NO x (intake gas oxygen concentration RO2c), a load index value representing the degree of load of the engine (fuel injection quantity qfinc), an atomization index value representing the degree of atomization of fuel in combustion chamber (fuel injection pressure Pcrc), and the highest flame temperature Tflame. Therefore, the B-region combustion-generated NO x quantity NOxB can be accurately estimated to accurately follow the actual relation between the above four peripheral condition quantities and the B-region combustion-generated NO x quantity NOxB.
  • the concentration of a gas in intake gas serving as a raw material for generating NO x intake gas oxygen concentration RO
  • fuel injection quantity qfinc is employed as the load index value representing the degree of load of the engine, but output torque of the engine may be employed as the load index value.
  • the inside wall temperature of the combustion chamber may be employed as the load index value.
  • fuel injection pressure Pcrc is employed as the atomization index value representing the degree of fuel atomization in the combustion chamber, but swirl ratio may be employed as the atomization index value.
  • excess air ratio in the combustion region (region B) may be employed as the atomization index value.
  • the highest flame temperature Tflame is estimated on the basis of engine speed NE and fuel injection quantity qfinc, but the highest flame temperature Tflame may be estimated on the basis of engine speed NE and output torque of the engine.
  • the concentration of a gas contained in intake gas and serving as a material for generation of NO x (intake-gas oxygen concentration), a load index value indicating the load of the engine (fuel injection quantity), an atomization index value indicating the degree of atomization of fuel within the combustion chamber (fuel injection pressure), and the highest flame temperature are selected as peripheral condition quantities in relation to gas mixture which affect the quantity of NO x generated in a combustion region as a result of combustion.
  • a combustion-generated NO x quantity per unit fuel quantity is obtained on the basis of the four peripheral condition quantities and a predetermined empirical formula which defines the relation between the four peripheral condition quantities and the combustion-generated NO x ratio.
  • the quantity of generated NO x is estimated through multiplication of the combustion-generated NO x ratio by the fuel injection quantity.

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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)
  • Exhaust Gas After Treatment (AREA)

Claims (6)

  1. Procédé d'estimation de quantité de génération de NOx pour un moteur à combustion interne, selon lequel une quantité de NOx générée dans une zone de combustion (B) en raison de la combustion d'un mélange gazeux contenant du carburant et de l'air est estimée sous la forme d'une quantité de NOx générée par combustion, la zone de combustion (B) étant une partie d'une chambre de combustion du moteur (10) et dans laquelle zone une combustion du mélange gazeux se produit,
    caractérisé en ce que
    la quantité de NOx générée par combustion est estimée sur la base d'un produit d'une puissance d'une valeur d'indice de charge qui représente un degré de charge (qfinc) du moteur (10), d'une puissance d'une valeur d'indice d'atomisation qui représente un degré d'atomisation (Pcrc) de carburant dans la chambre de combustion, d'une puissance de concentration en oxygène d'un gaz d'admission (R02c), et d'une fonction exponentielle dont l'exposant est déterminé en fonction d'une température de flamme la plus élevée (Tflame) dans une course de détente.
  2. Procédé d'estimation de quantité de génération de NOx pour un moteur à combustion interne selon la revendication 1, selon lequel la quantité de NOx générée par combustion est estimée sur la base d'au moins une valeur d'indice de charge qui représente le degré de charge du moteur et sert de quantité de condition périphérique.
  3. Procédé d'estimation de quantité de génération de NOx pour un moteur à combustion interne selon la revendication 2, selon lequel la valeur d'indice de charge est une valeur basée sur au moins un d'une quantité d'injection de carburant, d'un couple d'entraînement du moteur et d'une température de la surface de paroi interne de la chambre de combustion.
  4. Procédé d'estimation de quantité de génération de NOx pour un moteur à combustion interne selon la revendication 1 ou 2, selon lequel la quantité de NOx générée par combustion est estimée sur la base d'au moins une valeur d'indice d'atomisation qui représente le degré d'atomisation de chambre de carburant et sert de quantité de condition périphérique.
  5. Procédé d'estimation de quantité de génération de NOx pour un moteur à combustion interne selon la revendication 4, selon lequel la valeur d'indice d'atomisation est une valeur basée sur au moins un d'une pression d'injection de carburant, d'un rapport de tourbillon et d'un rapport d'air en excès dans une zone où une combustion se produit.
  6. Procédé d'estimation de quantité de refoulement de NOx pour un moteur à combustion interne prévu pour estimer, en tant que quantité de refoulement de NOx, une quantité de NOx contenue dans du gaz d'échappement libéré par un passage d'échappement du moteur vers l'extérieur, caractérisé en ce qu'il comporte les étapes consistant à :
    estimer une zone de combustion, la zone de combustion étant une partie d'une chambre de combustion dans laquelle une combustion de mélange gazeux contenant du carburant et de l'air se produit ;
    estimer, au moyen du procédé d'estimation de quantité de génération de NOx selon l'une quelconque des revendications 1 à 5, une quantité de NOx générée dans la zone de combustion en raison de la combustion du mélange gazeux comme quantité de NOx générée par combustion ;
    estimer une quantité de NOx dans une zone sans combustion, la zone sans combustion étant la partie restante de la chambre de combustion ; et
    estimer la quantité de refoulement de NOx sur la base de la quantité de NOx générée par combustion et de la quantité de NOx dans la zone sans combustion.
EP04024927A 2003-11-06 2004-10-20 Procédé d'estimation de quantité de NOx générée dans un moteur à combustion interne Expired - Lifetime EP1529941B1 (fr)

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