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
  • F02D41/0025—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
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D41/00—Electrical control of supply of combustible mixture or its constituents
  • F02D41/0002—Controlling intake air
  • F02D2041/0015—Controlling intake air for engines with means for controlling swirl or tumble flow, e.g. by using swirl valves
• • 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
  • F02D2041/0075—Estimating, calculating or determining the EGR rate, amount or flow by using flow sensors
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
  • Y02T10/00—Road transport of goods or passengers
  • Y02T10/10—Internal combustion engine [ICE] based vehicles
  • Y02T10/40—Engine management systems

Definitions

• the invention relates to the automotive field, and more particularly to the control and control of a motor vehicle engine, the engine being of the spark ignition type or of the Diesel type.
• EGR exhaust gas recirculation
• the quantity of polluting gases is therefore lower.
• the partial recycling of the exhaust gas at the intake is achieved by means of a recycling circuit comprising a controlled valve (generally called EGR valve).
• EGR valve a controlled valve
• the recycled engine exhaust gas rate or EGR rate ( ⁇ EGR ) is defined by the following relationship:
• Q EGR is the flow of exhaust gases recycled to the engine cylinders
• Q air is the fresh air supply rate of the engine. This recycling, however, is likely to increase significantly the amount of smoke in the exhaust if it is not properly adjusted and, in particular, if the amount of recycled exhaust gas is too large.
• the partial exhaust gas recirculation circuit can be arranged in two different configurations.
• the first is the partial recycling of so - called high - pressure exhaust gases, in which the gases are taken at the outlet of the exhaust manifold and reinjected into the intake manifold, ie the recycled gases are taken and reinjected into the high pressure part of the engine.
• the second is the partial recycling of the so-called low-pressure exhaust gas, in which the gases are taken at the outlet of the turbine or at the outlet of the particulate filter, and are reinjected upstream of the compressor, in the part of the engine which is more or less at atmospheric pressure. In the context of this invention, it will be more specifically the case of partial recycling of low pressure exhaust gas.
• the invention relates more particularly to diesel type engines with such recycling, provided with a double intake manifold.
• This double intake manifold allows two different pressure gas flows to arrive in each cylinder of the engine, thus creating a swirl or swirl effect, usually called “swirl”, and to better disperse the fuel and optimize its performance. combustion.
• a flowmeter is generally used, making it possible to translate a flow of gas into electrical information such as a current or a voltage.
• electrical information such as a current or a voltage.
• such a sensor is subject to numerous disadvantages, such as its cost, the disturbances of the measurement signal, the disturbances due to the return of pressure waves, the difficulties of calibration, the drifts and dispersions of the measurements as well as, in the case of partial recycling of low-pressure exhaust gases, the Fouling risks related to the proximity of the injection point of the recycled gases.
• the patent application FR0853483 in the name of the applicant proposes a method for calculating the air flow entering a dual intake manifold engine equipped with a high pressure EGR circuit. Adapting this method to an engine equipped with a low pressure EGR circuit is complex, and requires at least two gas pressure sensors.
• the object of the present invention is to provide a system and method for estimating, with a single gas flow meter, a gas temperature sensor and a gas pressure sensor, the total flow rate of gas admitted into an internal combustion engine. partial recirculation of the low pressure exhaust gas and a double intake manifold.
• the invention also aims to define calculation means for reducing the number of temperature and pressure sensors necessary for determining the air flow rate.
• the invention relates to a control system of an internal combustion engine.
• the engine is equipped with two intake manifolds, a main manifold and a secondary manifold, and is equipped, to regulate the flow rates of gas entering the engine cylinders, an intake flap upstream of the two collectors and d a swirl flap disposed between the intake flap and the secondary manifold.
• the engine is also equipped with a turbocharger and a fuel system. partial recycling of the exhaust gas discharging upstream of the supercharger.
• the system includes an electronic control unit receiving a reference gas temperature signal, a reference gas pressure signal, and a fresh air flow signal supplying the engine.
• the electronic control unit is configured to derive received signals, as a function of the degree of opening of the swirl flap and the rotational speed of the engine, an estimate of the flow rate of gas entering the engine, and an estimate of the flow rate of the engine. exhaust gas recycled by a barycentric calculation from one or more engine performance maps.
• the reference pressure corresponds to the pressure of the gases in one of the two collectors, the reference temperature corresponding to the common temperature of the gases in the two collectors,
• the mapped engine efficiency values are a function of the engine speed, the degree of opening of the swirl flap, and a gas density defined as the quotient of the reference pressure by the reference temperature.
• the reference pressure will be chosen equal to the measurable pressure in the main manifold.
• the engine performance maps are made so that, if a point of a map corresponds to a given torque (engine speed, gas density), one can find at least one other point of the or maps, corresponding substantially to the same torque (engine speed, gas density), and corresponding to a different degree of opening of the swirl flap.
• the electronic control unit has at least two "swirl index” mappings, each "swirl index” map containing engine performance values as a function of value pairs (engine speed, gas density), for a fixed degree of opening of the swirl flap.
• the means for evaluating the reference pressure is a pressure sensor disposed in the main manifold, or disposed between the intake flap and the swirl flap.
• the means for evaluating the reference temperature may be a temperature sensor disposed between the intake flap and the engine cylinders.
• the reference temperature evaluation means may also be a temperature sensor disposed upstream of the intake flap.
• the electronic control unit also has a monotonous map making it possible to connect the values of the degree of opening of the swirl flap and the section values by a strictly monotonic function.
• the section values obtained by the monotonic mapping correspond to the cross section of the passage delimited by the swirl flap, in the sense of the Barré de Saint-Venant equation for the fluids.
• the cross-section of the swirl flap is the section for which the Saint-Venant Barré equation for fluids makes it possible to find the same relationships between gas temperature, gas flow, and gas pressures upstream and downstream of the flap. , than those measurable on a test bench.
• the electronic control unit is configured to evaluate a non-mapping performance in the yield map (s) corresponding to a current engine speed, a current gas density and a degree of opening.
• current of the swirl flap itself associated with an effective section by the cross-section mapping, calculating this output as the center of gravity: a first mapped value of output corresponding to the same engine current regime and current gas density , and at a first degree of opening of the swirl flap,
• the cross-section distances are the differences between the cross-sections of the points used in the calculation and the cross-section corresponding to the point to be calculated.
• the electronic control unit is configured to calculate the flow of gas entering the cylinders of the engine, calculating this flow as a value proportional to the product of the gas density by the engine speed and the efficiency of the motor.
• the electronic control unit is configured to calculate the flow rate of recycled gas using the flow rate of gas entering the engine cylinders, and the fresh air flow, by performing a balance of mass on the gases contained in the engine ducts between the injection point of recycled gas and the engine cylinders.
• the electronic control unit can be configured to calculate the recycled gas flow, calculating this flow as the difference between the flow of gas entering the engine and the flow of fresh air.
• the electronic control unit can have a mapping connecting by a strictly monotonous function the degree of opening of the shutter and an effective section of this intake flap, and the electronic control unit can be configured to calculate the flow of recycled gas, calculating this flow as the difference between the flow rate of gas entering the engine and the flow of fresh air, to which is added a term proportional to the derivative with respect to the time of a p gas density -, and a term proportional to the derivative relative to
• T the reference temperature
• Qmoteur represents the total flow rate of gas entering the engine cylinders S e y represents the cross section of the intake flap
• the subject of the invention is a method for evaluating the quantity of exhaust gas recycled in an internal combustion engine equipped with two intake manifolds, a main collector and a secondary collector, and equipped with to regulate the flow rates of gas entering the engine cylinders, an intake flap upstream of the two collectors and a swirl flap disposed between the intake flap and the secondary collector, also equipped with a turbocharger supercharging system and a partial exhaust gas recirculation circuit opening upstream of the supercharging compressor, the method comprising the following steps: a reference pressure corresponding to the pressure of the gases in the main manifold is measured,
• a fresh air flow is measured which supplies the motor, an effective section of the swirl flap is evaluated, the effective section being a monotonic function of an opening degree of the swirl flap,
• a volumetric efficiency of the engine is evaluated by estimating a barycentre of two mapped performance values, weighted by the distances between the cross sections of the mapped points and the effective section of the point to be evaluated.
• the rate of recycled gas is evaluated as a function of the reference pressure, the reference temperature, the fresh air flow rate, the engine rotation speed and the volumetric efficiency of the engine.
• FIG. 1 is a diagrammatic view of an engine equipped with a control system according to the invention
• FIG. 2 is a block diagram summarizing an example of a process implemented in the invention for evaluating the flow of gas recycled in the engine illustrated in FIG. 1.
• FIG. 1 illustrates by way of example a combustion engine 1 internal diesel type, equipped with a turbo supercharger system and a partial exhaust gas recirculation circuit.
• the engine has four cylinders 14, but could include any number of cylinders.
• the air admitted into the engine passes firstly through an air filter 2, a flowmeter 16, then through a compressor 3a of a turbocharger 3.
• the flowmeter may be a portion of a gas line equipped with a sensor with hot wire.
• the turbocharger 3 is composed of a compressor 3a and a turbine 3b arranged on the same axis, so that the turbine 3b can drive the compressor 3a.
• the air thus compressed passes through an intake air exchanger 4 for cooling, then into an intake pipe 5 before being admitted into the cylinders of the engine 14 via a double intake manifold 13
• the double manifold 13 comprises a first main manifold 13a and a secondary collector 13b.
• An intake flap 18 regulates the flow of air passing from the intake duct 5 into the double manifold 13.
• the air flow then splits between the main manifold 13a and the secondary collector 13b.
• a swirl flap 19 limits the air flow in the secondary collector 13b.
• the main manifold 13a opens through four arrival lines in the four cylinders 14 of the engine; the secondary manifold 13b opens by four other arrival lines in the same four cylinders 14 of the engine.
• the gases from the combustion in the cylinders are discharged via an exhaust manifold 6 and cause the Turbocharger turbine 3b 3. These exhaust gases are then discharged via an exhaust pipe 7 and a particulate filter 8 to be discharged into the atmosphere. Part of this exhaust gas is taken at the outlet of the particle filter 8 by a bypass line 9, which brings these gases upstream of the compressor 3a where they mix with fresh air from the air filter 2.
• the gases taken by the bypass line 9 are at a pressure lower than the pressure of the gases in the intake manifold 13 and the exhaust manifold 6. Such a recycling is then called a low pressure recirculation of the exhaust gas.
• An exhaust valve 10 is disposed on the exhaust pipe 7 downstream of the bypass line 9.
• An EGR valve 1 1 is disposed on the branch line 9.
• the degree of opening of the exhaust valve 10 regulates the gas pressure in the bypass line 9.
• the degree of opening of the EGR valve 1 1 makes it possible, in combination with the degree of opening of the exhaust valve 10, to vary the gas flow rate returned by the bypass line 9 to the compressor 3a.
• a cooler 12 is disposed on the bypass line 9 between the EGR valve 1 1 and the inlet of the compressor 3a.
• a temperature sensor 20 is disposed in the intake duct 5, between the intake air exchanger 4 and the intake flap 18.
• a pressure sensor 21 is disposed in the main collector 13a.
• An electronic control unit (ECU), referenced 15, controls in particular the quantities and the moments of fuel injection into the cylinders 14 of the engine, and also controls the fresh air flow and the rate of recycled gases sent to the cylinders. 14.
• the electronic control unit 15 comprises, in a conventional manner, a microprocessor or central unit, RAMs, ROMs, analog / digital converters and different input and output interfaces.
• the ECU 15 receives by connections 22, 23, and 24, respectively, the values measured by the flowmeter 16, the temperature sensor 20 and the pressure sensor 21.
• the ECU 15 also receives, via a connection 27, the speed of motor rotation N, measured by a motor speed sensor (not shown) disposed at one of the engine cylinders. Depending on the operating point of the motor and the desired EGR rate, the ECU sends control signals through the connection 25 to change the position of the flap 18 to regulate the total amount of air and recycled gases admitted to the units. engine cylinders; the ECU 15 sends control signals via the connection 26 to change the position of the flap 19, and therefore the level of eddy of the air entering the cylinders 14 of the engine; the ECU sends control signals respectively through connections 28 and 29 to modify the positions of the valves 10 and 11, and in doing so, to regulate the rate of EGR.
• the ECU receives, through these same connections 25, 26, 28 and 29, signals indicating the respective degree of opening of the flaps 18, 19 and the valves 10 and 1 1.
• the ECU 15 has two maps 30 and 31 to read engine performance values.
• the ECU 15 may optionally have more than two engine yield maps.
• the ECU 15 also has a map 42, for reading according to the angular position x of the swirl flap, an effective section Se x delimited by this flap.
• the ECU 15 finally has a map 43, to read depending on the angular position of the intake flap is a cross section If there delineated by this component.
• the cross sections of the map 42 are determined by measurements on a test bench, so as to verify the Saint-Venant Barré equation for a fluid of temperature T, passing through a conduit of the cross section considered, entering a pressure P and out at a pressure P SW iri, with a flow rate Q swl ⁇ that is to say the equation:
• ⁇ is the dimensionless ratio of the specific heats for air, having the value 1, 4 p is the gas pressure upstream of the swirl flap
• R is the air constant, with the value of 287 J / kg / K swirl is the gas pressure downstream of the swirl flap
• Mapping 43 is also determined on test benches, so as to verify the Barre de Saint-Venant equation for the admission component, namely:
• Each of the mappings 30 and 31 reads a series of values ⁇ r of engine fill efficiency, corresponding to a fixed position of the swirl flap. For a given position of the swirl flap, this filling performance of the engine is a function of two p variables, a gas density - and a regime N,
• the maps 30 and 31 can be established on test benches by carrying out measurement series of the engine gas flow entering the cylinders of a reference engine (equipped with a flow meter at the inlet of the engines). cylinders), as well as measurements of the corresponding gas density values. The following relation is used to define the efficiency ⁇ r :
• P is the pressure in the main manifold
• T is the common gas temperature at the inlet flap and in the two manifolds 13a and 13b x is the open position of the swirl flap
• Qmotor is the total flow of gas entering the engine cylinders
• T swirl flap fully open and for one or more positions of the swirl flap other than the full open position.
• one set corresponding to the mapping 30 the values ⁇ r at a position 25% of angular travel of opening of the swirl flaps and is set in the mapping 31, the values corresponding to ⁇ r a position at 98% angular opening stroke of the swirl flap.
• the flaps 18 and 19 are rotary flaps, but they could be replaced by other types of control valves. Instead of using the angular opening position of the flap, it is then possible to use another variable connected to the movement of the shutter member of the valve.
• the invention proposes to use a barycentric method, based on the passage cross sections. delimited by the swirl flap 19, sections associated with the open positions of the considered points.
• a yield corresponding to an opening stroke x the following section values are extracted from the map 42:
• Q EGR Qmoteur - Q m r ms (Equation 4) Where Q mr is the fresh air flow rate measured by flowmeter 16.
• equation I b is used which gives, after mathematical simplification:
• QEGR + Qmr The Q EGR and / or ⁇ EGR values thus estimated can then be used to manage the positions of the valves 10 and 1 1 making it possible to vary Q EGR and ⁇ EGR .
• FIG. 2 summarizes the calculation process implemented by the electronic control unit 15 of FIG. 1 in order to calculate the flow rate of gas entering the engine, and then to deduce the recycled gas flow rate.
• the electronic control unit has tables of values represented by the references 30, 31, 32,
• Tables 30, 31, 32 are engine performance maps as a function of two variables, the variable N, or engine rotation speed, and the reduced variable P / T, or gas density, calculated from the temperature T and pressure P measured by the sensors 20 and 21 of Figure 1, respectively.
• Mapping 30 represents the engine efficiency for an opening position xi of the swirl flap.
• Mapping 31 represents the efficiency of the engine for a position x 2 opening of the swirl flap.
• the control unit may have secondary mappings corresponding to other opening positions of the swirl flap than xi or x 2 , for example a map 32 representing the engine efficiency for an opening position X 1 of the flap. sybarite.
• the electronic control unit has a list 40 in which are recorded the positions X 1 , X 2 , Xi of the swirl pane for which mapping is available.
• the electronic control unit also has a map 42 connecting the possible positions x for the swirl flap, and the effective section corresponding to these positions, according to the equation l a.
• the electronic control unit receives, as input data, the position x of the swirl flap, the pressure P measured by the sensor 21, the temperature T, measured by the sensor 20, the rotation speed N of the engine, and the flow rate. Q mr frms measured by the flowmeter 16.
• ECU identifies maps 30 and 31 corresponding to the two values in the list 40 framing closer the measured opening x of the swirl component.
• the ECU reads in these maps 30 and 31 the efficiency values corresponding to the selected values X 1 , x 2 , that is, ⁇ (IN, -P, X 1 ⁇ and ru (N, -P, x 2 ⁇ I. mapping 42, the ECU deduces the cross-sections S 1, S 2 and Se x corresponding to the three opening positions X 1 , x 2 i and x respectively, whereas the ECU estimates at step 46 the efficiency of the motor corresponding to the opening x of swirl flap, using the following barycentric formula:
• the ECU deduces in step 47 the flow of gas entering the engine, using equation 2.
• the ECU then deduces in step 48, the flow of exhaust gas recycled to the engine, for example using equation 4, and taking into account the flow of fresh air
• the invention is not limited to the embodiment described, and may be subject to many variants.
• the yield maps 30, 31, 32 ... can be indexed directly on the effective section corresponding to the position of the intake flap for which they were made. In this way, the corresponding sections S 1, S 2 ... are avoided in each case in the map 42.
• the temperature sensor can be arranged inside the double collector 13, that is to say between the shutter. intake 18 and the cylinders 14 of the engine.
• the pressure sensor 21 could, without changing the calculations, be between the docking flap 18 and the area where the collector 13 splits into two collectors 13a and 13b. It is also possible to envisage variants where this pressure sensor would be in the collector 13b, while mapping in the maps 30 and 31 engine efficiencies defined from this pressure value.
• the invention can be used to calculate the flow rate of recycled gas in an engine equipped only with a low-pressure gas recirculation circuit, or to calculate the flow rate of recycled gas in an engine equipped with a low-pressure recirculation circuit. gas and a high-pressure gas recirculation circuit, when this circuit of High pressure recycling is closed. It is possible to group together all available performance values in a single map.
• the method described above makes it possible to simply calculate the quantity Q EGR of recycled gases returned to the cylinders of the engine, using only, in terms of measurement instrumentation, a pressure sensor and a temperature sensor, as well as a fresh air flow meter which is usually already present to optimize other engine operating variables. Calculations of physically well-identified values are used for the calculation instead of the complex calibration functions of the prior art. The reliability of the estimates is improved, the control of polluting discharges also.

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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)

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• 2009
  • 2009-04-02 FR FR0952145A patent/FR2944058B1/fr not_active Expired - Fee Related
• 2010
  • 2010-02-15 EP EP10708342A patent/EP2414658A1/de not_active Withdrawn
  • 2010-02-15 WO PCT/FR2010/050245 patent/WO2010112719A1/fr active Application Filing

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