FR2886339A1 - Control and command system for i.c. engine with exhaust gas recirculation (EGR) has recirculation pipe equipped with gas flow rate measuring unit - Google Patents

Abstract

The control and command system for a motor vehicle engine group (1) with an electronic command unit (2) and an EGR pipe (20) with a valve (21) connected to the engine air feed pipe (12), which has a control valve (22), has the EGR pipe equipped with a unit (23) for measuring the gas flow rate in the pipe. The measurements are fed to the command unit, which has processors (26, 28) and regulators (25, 27) to adjust the EGR and air feed pipe valves accordingly.

Description

System and method for controlling and controlling a motor group of

motor vehicle.

  The invention relates to the automotive field, and more particularly to the control and control of a motor vehicle engine group, the engine being of the spark-ignition type or of the Diesel type.

  A motor group is a set of assembled parts, including a motor and its auxiliaries essential to its operation.

  Restrictions on the emission of exhaust pollutants from internal combustion engines of motor vehicles require the development of more and more effective abatement strategies. One of these strategies is to recirculate a portion of the exhaust gas from combustion using a partial exhaust gas recirculation (EGR) line. The reintroduction of the exhaust gases at the intake of the engine makes it possible to reduce the combustion temperature inside the cylinders and thus to define a compromise between the emission of the particles and the emission of nitrogen oxides. NOx.

  The recirculated engine exhaust gas rate or EGR rate ('rEGR) is defined by the following relation: rEGR QEGR = QEGR = in which: Q EGR + Qair Q engine QEGR is the flow of exhaust gas recirculated at the inlet of the engine, Qair is the fresh air supply flow rate of the engine, and Qmotor = QEGR + Qa, r is the engine gas supply flow rate.

  Thus, by providing recirculation of the exhaust gas, inert gases are injected into the engine cylinders, which reduces the amount of nitrogen oxides produced by the engine.

  This recirculation, however, is likely to significantly increase the amount of smoke in the exhaust gas if it is not properly adjusted and, in particular, if the amount of recirculated exhaust gas is too large.

  It is therefore necessary to precisely adjust the rate of recirculated exhaust gas or EGR rate.

  Thus, according to one aspect of the invention, there is provided a control system and control of a motor vehicle engine group. The vehicle is equipped with an electronic control unit, and said engine group comprises an exhaust gas recirculation duct of the engine provided with a controlled recirculation valve and connected to an air supply duct of the engine. Said engine air supply duct comprises a controlled intake valve located upstream of the coupling, and said system comprises means for determining the fresh air supply flow rate of the engine. The recirculation duct is provided with means for measuring the recirculation flow rate of the engine exhaust gases in said recirculation duct. The electronic control unit comprises: first means for regulating the fresh air supply flow rate of the engine to a reference flow rate for supplying fresh air to the engine produced by first means for generating the setpoint flow rate; fresh air supply to the engine; and second means for regulating the recirculation flow rate of the exhaust gases of the engine on a reference flow rate of the recirculation of the engine exhaust gases produced by second means for generating the desired flow rate of recirculation of the exhaust gas. engine exhaust.

  It is then possible to precisely control the rate of recirculated gas or EGR rate and thus optimize an equilibrium between the amount of nitrogen oxides and the fumes discharged into the engine exhaust gas.

  In a first embodiment, the first means for regulating the fresh air supply flow rate of the engine are adapted to control the opening position of said intake valve as a function of the fresh air supply flow rate of the engine and the set flow rate of the fresh air supply to the engine. In addition, the second engine exhaust gas recirculation flow control means are adapted to control the opening position of said recirculation valve as a function of the engine exhaust gas recirculation flow rate and the engine exhaust flow rate. engine exhaust gas recirculation setpoint The recirculated exhaust gas rate can be precisely regulated by acting on the open positions of the two controlled valves.

  In a second embodiment, the first means for regulating the fresh air supply flow of the engine are adapted to control the opening position of said recirculation valve as a function of the fresh air supply flow rate of the engine and the engine. setpoint flow of fresh air supply of the engine. In addition, the second engine exhaust gas recirculation flow control means are adapted to control the opening position of said intake valve as a function of the engine exhaust gas recirculation flow rate and the engine exhaust flow rate. engine exhaust gas recirculation reference.

  The rate of recirculated exhaust gas can be precisely regulated by acting on the open positions of the two controlled valves.

  For example, the means for determining the fresh air supply flow rate of the engine comprise a flow meter or an estimator of the fresh air supply rate of the engine. In addition, the means for measuring the recirculation flow of the engine exhaust gas comprise a flow meter.

  In addition, said first and second regulating means each comprise a regulator implementing a respective function Proportional Integral Derivative or PID.

  A Proportional Integral Derivative or PID function is a control function (generally a regulation) in which the output of the device that performs this function is proportional to a linear combination of the input, its integral of time and its speed of variation.

  Such a function is very simple to implement, and allows to obtain very good performance for this application.

  In a preferred embodiment, said first and second regulating means are adapted to control a pre-positioning of the opening position of the valve respectively controlled according to engine operating parameters, for example as a function of engine torque and / or the speed of rotation of the motor.

  The pre-positioning of the recirculation and intake valves make it possible to anticipate the variations of the positioning controls, and to obtain a better enslavement under transient conditions.

  In an advantageous embodiment, said first and second elaboration means respectively comprise a memorized map of the target flow rate to be developed as a function of engine operating parameters, for example the engine rotation speed and / or the flow rate of the engine. engine fuel supply, and / or engine torque.

  In addition, said first and second generating means respectively comprise means for correcting said setpoint flow rate provided by the respective stored map as a function of engine operating parameters, for example the temperature of the engine coolant, and / or the atmospheric pressure, and / or the temperature in the intake manifold of the engine.

  This makes it possible to improve the accuracy of the fresh air supply and recirculated exhaust gas flow rates.

  According to another aspect of the invention, there is also provided a method for controlling and controlling a motor vehicle engine group, in which the recirculation flow rate of the engine exhaust gases is measured in a recirculation duct of the engine. engine exhaust gas, it regulates the flow of fresh air supply of the engine on a set flow rate of fresh air supply of the engine, and the flow rate of recirculation of engine exhaust gas is regulated on a flow rate engine exhaust gas recirculation reference.

  Other objects, features and advantages of the invention will appear on reading the following description of some non-limiting examples and with reference to the appended drawings, in which: FIG. 1 is a block diagram of a first embodiment of FIG. embodiment of a system according to one aspect of the invention; FIG. 2 is a block diagram of a second embodiment of a system according to one aspect of the invention; Figures 3 and 4 are block diagrams of the fresh air supply rate regulating means of the engine and the engine exhaust gas recirculation flow control means according to an aspect of the first embodiment; FIGS. 5 and 6 are more detailed block diagrams of means for regulating the fresh air supply flow rate of the engine and means for regulating the flow rate of recirculation of the engine exhaust gases of FIGS. 3 and 4; and FIGS. 7 and 8 are block diagrams of the means for generating the fresh air supply setpoint of the engine and means for developing the recirculation flow rate of the engine exhaust gases.

  As illustrated in FIG. 1, the system comprises a power unit 1 and an electronic control unit 2. The power unit 1 comprises an internal combustion engine shown schematically under the reference 3 and comprising four cylinders.

  In the example shown, the fresh air admitted 4 passes through an air filter 5 mounted on the air intake duct 6. The air is compressed in a compressor 7 of a turbocharger unit 8 comprising the compressor 7 and an expansion turbine 9 mounted on the same mechanical drive shaft 10 as the compressor 7, so that the turbine 9 can rotate the compressor 7. The compressed air heated by the compression is cooled by an exchanger 11 mounted on a supply line 12 bringing the compressed air 'to the intake manifold 13 of the engine 3.

  An exhaust pipe 14 brings the exhaust gases from an exhaust manifold: from the engine 3 to the turbine 9. The exhaust gases from the turbine 9 are expanded and pass through a catalyst assembly and particulate filter. 16 An exhaust system 18 discharges the exhaust gases 19 from the engine 3 into the atmosphere.

  A recirculation duct 20 recirculates part of the exhaust gas from the engine 3, from the exhaust duct 14 to the supply duct 12. The recirculation duct 20 is provided with a recirculation valve 21 or valve EGR, to change the amount of recirculated exhaust gas. The feed pipe 12 comprises an inlet valve or intake flap 22 for changing the amount of fresh air supplied to the engine 3. The inlet valve 22 is located upstream of the connection between the recirculation duct 20 and the supply line 12.

  The recirculation duct 20 is further provided with a flowmeter 23, for measuring the flow QEGR, mes of the recirculated exhaust gas in the recirculation duct 20. The duct 6 also comprises a flowmeter 24 for measuring the flow rate Qair .mes supply fresh air to the engine 3.

  The electronic control unit 2 comprises a first control module 25 of the air flow rate Qair, mes fresh air supply of the engine 3 on a set flow Qair, cons developed by a first module 26 development of the flow rate Qair , fresh air supply of the engine 3.

  The electronic control unit 2 further comprises a second regulation module 27 of the flow QEGR, mes of recirculation of the exhaust gas of the engine 3 on a reference flow QEGR, rec recirculation of the exhaust gas engine 3 developed by a second development module 28 setpoint flow QEGR, rec recirculation of the engine exhaust gas 3.

  The flow meter 24 transmits, by a connection 29, the air flow Qair.mes to the first control module 25. In a variant, the flowmeter 24 may be replaced by a module for estimating the fresh air supply flow rate of the engine 3. The flowmeter 23 transmits to the second control module 27 the measurement of the flow QEGR, mes of exhaust gases recirculated in the recirculation duct 20 by a connection 30.

  The first generation module 26 transmits, to the first regulation module 25, the setpoint flow Qair, fresh air supply cons of the engine 3, by a connection 31. The second processing module 28 transmits, to the second module 27, the reference flow rate QEGR, recirculated exhaust gas cons, through a connection 32.

  The first control module 25 of the fresh air supply flow of the engine 3 controls, via a connection 33, the open position of the intake valve 22. The second regulation module 27 of the flow for recirculating the exhaust gas from the engine 3 controls, via a connection 34, the open position of the recirculation valve 21.

  Such a system makes it possible to control the rate of EGR.

  Figure 2 illustrates another embodiment of a system according to one aspect of the invention. With respect to the system of FIG. 1, the controls of the intake valves 22 and recirculation valves 21 are reversed. Indeed, the first control module 25 of the fresh air supply flow of the engine 3 controls the opening position of the recirculation valve 21, via a connection 35. In addition, the second module of regulation 27 of the exhaust gas recirculation flow of the engine 3 controls the open position of the intake valve 22 via a connection 36.

  The following figures illustrate in more detail a system according to the embodiment of FIG. 1. Of course, the following examples are easily transferable to a system according to the embodiment of FIG. 2.

  FIG. 3 illustrates an exemplary embodiment of the second control module 27 of the exhaust gas recirculation flow of the engine 3. The second control module 27 comprises a subtracter 37 which subtracts the QEGR measurement, mes from the recirculation flow rate. setpoint QEGR, recirculated exhaust gas cons. These values are respectively transmitted by the connections 30 and 32. The difference AQEGR calculated by the subtracter 37 is transmitted to a calculation module 38. The calculation module 38 outputs a control of the opening position of the recirculation valve. 21, via the connection 34.

  FIG. 4 shows an exemplary embodiment of the first fresh air supply flow control module of the engine 3. The first control module 25 comprises a subtractor 39 which subtracts the measured flow rate Qair, my supply of fresh air from the engine 3 and the reference flow rate Qa, r, cons of fresh air supply of the engine 3. These values are respectively transmitted by the connections 29 and 31. The difference AQair calculated by the subtractor 39 is transmitted to a calculation module 40. The calculation module 40 outputs control of the open position of the intake valve 22 via the connection 33.

  FIG. 5 illustrates an exemplary embodiment of the calculation module 40 of the first regulation module 25. The calculation module 40 comprises a derivative integral proportional regulator or PID 41, a prepositioning module 42, and an adder 43. The PID regulator 41 performs a treatment of the AQair difference transmitted by the subtractor 39. The pre-positioning module 42 allows the first control module 25 to anticipate opening positioning control variations of the intake valve 22. The adder 43 receives a prepositioning information from the pre-positioning module 42 as well as a command from the PID regulator 41 making it possible to refine the opening position control of the intake valve 22.

  FIG. 6 represents an exemplary embodiment of the calculation module 38. The calculation module 38 comprises a derivative integral proportional regulator or PID regulator 44, a pre-positioning module 45 and an adder 46. The pre-positioning module 45 allows to anticipate the variations of the opening position control of the recirculation valve 21. The PID regulator 44 receives as input the difference AQEGR transmitted by the subtractor 37. The adder 46 makes it possible to refine the control of the position of opening of the recirculation valve 21 by means of the output of the PID regulator 44.

  Control of the exhaust gas recirculation rate or EGR rate is therefore provided by two control loops. A first fresh air supply flow control loop of the engine 3 controls the position of the intake valve 22, and a second recirculated exhaust gas flow control loop controls the open position of the valve. recirculation 21.

  FIG. 7 illustrates an exemplary embodiment of the first elaboration module 26 of the setpoint flow Qair, cons of fresh air supply of the engine 3. The data necessary for the operation of the first production module 26 are generally already present at the level of the electronic control unit 2 and used by other systems on board the vehicle.

  The first elaboration module 26 of the setpoint flow Qair, fresh air supply set of the engine 3 comprises a stored map 47 of the setpoint flow Qair, cons fresh air supply of the engine 3 according to the speed of rotation of the engine 3 and the fuel supply rate of the engine 3. In addition, this setpoint flow can be corrected according to the operating parameters of the engine 3.

  In this example, the setpoint flow Qair, fresh air supply of the engine 3 is corrected according to the temperature of the fresh air supply of the engine, and the atmospheric pressure.

  The correction as a function of the temperature of the air is provided by a multiplier 50 receiving as input data provided by maps 48 and 49. The cartography 48 has as input parameters the engine rotation speed and the fuel flow rate. 3. The cartography 49 has as input parameters the fresh air supply temperature of the engine 3. A subtractor 5isprocessed at the fresh air supply setpoint flow rate provided by the stored map 47, the value transmitted. by the multiplier 50. Similarly, a subtracter 55 subtracts a correction being a function of the atmospheric pressure provided by a multiplier 54. The multiplier 54 receives data from a map 52 and a map 53. The map 52 input parameters motor rotation speed and engine fuel flow rate. The mapping 53 has the input parameters atmospheric pressure.

  The number of corrections is not limited, and depends on the operating parameters of the engine that is taken into account. The first generation module 26 thus provides a corrected set flow rate Qair, fresh air supply cons of the engine 3.

  FIG. 8 is an exemplary embodiment of the second elaboration module 28 of the reference flow rate of the exhaust gas recirculation of the engine 3. Its embodiment is similar to that of the first production module 26 of FIG. 7.

  The second processing module 28 includes a stored map 56 of the reference flow QEGR, cons recirculated exhaust gas. Corrections are made according to several operating parameters of the engine 3. A subtractor 60 performs a correction of the target flow rate provided by the caratograph 56 as a function of the fresh air supply temperature of the engine 3 by means of data transmitted by a multiplier 59.

  The multiplier 59 receives as input data from a map 57 and a map 58. The cartography 57 has as input parameters the engine rotational speed and the fuel supply rate of the engine. The cartography 58 has as input parameters the temperature of the fresh air supplying the engine. A subtractor 64 performs a correction of the reference flow rate of the recirculated exhaust gas as a function of the atmospheric pressure, from data transmitted by a multiplier 63.

  The multiplier 63 receives as input data transmitted by a cartography 61 and a map 62. The cartography 61 has as input parameters the rotational speed of the engine and the fuel supply rate of the engine. The cartography 62 has as input parameters the atmospheric pressure.

  The examples of the parameters taken into account to make corrections on the calculations of the flow rates of fresh air supply and recirculated exhaust gas are not exhaustive.

Claims (12)

  1. Control and control system of a motor vehicle engine unit (1) equipped with an electronic control unit (2), said engine group (1) comprising an exhaust gas recirculation duct (20). an engine (3) having a recirculation valve (21) controlled and connected to a supply line (12) for engine air, said engine supply line (12) comprising an intake valve (22) controlled, and said system comprising means for determining the fresh air supply rate of the engine, characterized in that the recirculation duct is provided with means (23) for measuring the gas recirculation flow rate. exhausting the motor into said recirculation duct (20), and the electronic control unit (2) comprises: first airflow regulating means (25), mes for supplying fresh air to the engine at a setpoint flow rate Qair, cons of fresh air supply engine developed p ar of the first means (26) for generating the setpoint flow Qair, for supplying fresh air to the engine; and second regulating means (27) for the flow rate of recirculation of the engine exhaust gases to a reference flow rate QEGR, a recirculation quantity of the engine exhaust gases produced by second elaboration means ( 28) of the reference flow 25 of the engine.   2. System according to claim 1, wherein the first control means (25) of the flow QEGR, rec recirculation of exhaust gas Qair, mes fresh air supply of the engine are adapted to control the open position said intake valve (22) as a function of the air flow rate Qair, the fresh air supply of the engine and the set flow rate Qair, fresh air supply of the engine; and the second regulation means (27) of the flow rate QEGR, the engine exhaust gas recirculation chambers are adapted to control the opening position of said recirculation valve (21) as a function of the flow rate QEGR, recirculation mes engine exhaust gas and reference flow recirculation of the engine exhaust gas.   3. System according to claim 1, wherein - the first control means (25) of the air flow Qair, mes fresh air engine are adapted to control the open position of said recirculation valve (21) in flow function Qair.mes of fresh air supply of motor and set flow Qair.cons of supply of fresh air to the engine; and the second control means (27) of the flow QEGR, recirculation of the engine exhaust gas are adapted to control the open position of said intake valve (22) according to the flow QEGR, recirculation mes the engine exhaust gas and the reference flow rate QEGR, recirculation of the engine exhaust gas.   4. System according to any one of the preceding claims, wherein the means for determining the flow Qair.mes fresh air supply engine include a flowmeter (24) or an estimator of the fresh air supply rate of the engine. (3), and wherein the means for measuring the engine exhaust gas recirculation flow rate comprise a flow meter (23).   5. System according to any one of the preceding claims, wherein said first and second regulating means (25,27) each comprise a regulator (41,44) implementing a respective function Proportional Integral Derivative.   The system of any preceding claim, wherein said first and second regulating means (25,27) are adapted to control a pre-positioning (42,45) of the open position of the valve (21). , 22) respectively controlled according to engine operating parameters.   QEGR, cons of The system of claim 6, wherein said parameters for said pre-positioning include the engine torque and / or the rotational speed of the engine.   8. System according to any one of the preceding claims, wherein said first and second elaboration means (25,27) respectively comprise a stored map (47,56) of said setpoint flow to be developed according to operating parameters of the engine.   The system of claim 8, wherein said engine operating parameters of said stored maps (47,56) include the engine rotational speed and / or the engine fuel delivery rate, and / or the engine torque .   The system of claim 8 or 9, wherein said first and second generating means (25,27) respectively comprise means for correcting said setpoint rate provided by the respective stored map (47,56) according to parameters. engine operation.   The system of claim 10, wherein said engine operating parameters used by said correction means include engine coolant temperature, and / or atmospheric pressure, and / or temperature in the intake manifold. of the engine (3).   12. A method of controlling and controlling a motor unit (1) of a motor vehicle characterized in that it measures the flow QEGR. recirculating the exhaust gases from the engine in a recirculation duct (20) of the engine exhaust gas, the flow rate Qa is regulated; R, mes of fresh air supply of the engine on a Qair setpoint flow, cons of fresh air supply of the engine, and one regulates the flow QEGR. recirculating engine exhaust gas at a set flow rate QEGR, rec recirculation of the engine exhaust gas.