EP4430288A1 - Procédé d'estimation à basse fréquence d'un débit de gaz d'échappement recyclés à l'admission d'un moteur à combustion interne - Google Patents
Procédé d'estimation à basse fréquence d'un débit de gaz d'échappement recyclés à l'admission d'un moteur à combustion interneInfo
- Publication number
- EP4430288A1 EP4430288A1 EP22813512.5A EP22813512A EP4430288A1 EP 4430288 A1 EP4430288 A1 EP 4430288A1 EP 22813512 A EP22813512 A EP 22813512A EP 4430288 A1 EP4430288 A1 EP 4430288A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- rate
- πmoy
- expansion
- exhaust gas
- venant
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
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
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
- F02M26/45—Sensors specially adapted for EGR systems
- F02M26/46—Sensors specially adapted for EGR systems for determining the characteristics of gases, e.g. composition
- F02M26/47—Sensors specially adapted for EGR systems for determining the characteristics of gases, e.g. composition the characteristics being temperatures, pressures or flow rates
Definitions
- TITLE Method for low frequency estimation of a flow rate of recycled exhaust gases at the intake of an internal combustion engine
- the present invention relates to motor vehicle internal combustion engines of the spark ignition type (gasoline) or of the compression ignition type (diesel), and relates in particular to a partial exhaust gas recirculation circuit at the exhaust of such an engine, called a circuit EGR, for "ExhaustGaz Recirculation” in Anglo-Saxon terms or “Recirculation des Gaz d'Echappement” in French.
- a circuit EGR for "ExhaustGaz Recirculation” in Anglo-Saxon terms or “Recirculation des Gaz d'Echappement” in French.
- the recirculation of exhaust gases is a process making it possible to limit the production of nitrogen oxides (NOx) in the combustion gases of a diesel engine, or to reduce the fuel consumption of gasoline engines.
- This EGR process consists of taking gases from the exhaust and sending them to the intake, for example downstream of an engine air flow control valve.
- NOx nitrogen oxides
- This EGR process consists of taking gases from the exhaust and sending them to the intake, for example downstream of an engine air flow control valve.
- the action on the formation of NOx can go up to 50% of global reduction and is interpreted by a reduction in the temperatures of combustion gases due to the dilution and a consequent slowing down of the kinetics of formation of the pollutant.
- the reduction in fuel consumption is due to the engine being less sensitive to knocking, which makes it possible to increase the ignition advance and to the reduction in losses by engine pumping, the supply of recycled gases making it possible to increase the pressure in the engine intake manifold for the same air flow value necessary for torque production.
- the quantity of recycled gas is estimated using a differential pressure sensor at the level of a valve regulating the flow of the EGR circuit, called the EGR valve. This sensor makes it possible to estimate the flow which has just passed through the level of the valve, called the EGR flow.
- EGR rate that is to say, the ratio between the exhaust gas flow at the intake and the total flow of gases admitted into the engine ( air and recycled gases), which affects the level of NOx pollutants or fuel consumption.
- Poor control of the EGR flow rate can lead to undesired effects that can compromise the operation of the vehicle. drastic in terms of degraded reliability or non-compliance with regulatory pollution control standards.
- the difficulty in estimating the EGR flow is due to the fact that a flow sensor is not used at the EGR valve itself, which would be expensive and inaccurate. Instead of such a flowmeter, a differential pressure sensor is employed which measures the difference between the pressure downstream and upstream of the valve. The flow rate passing through the valve is estimated based on a model which uses the measured differential pressure and the opening level of the valve. Even if this model can provide very precise results, the differential pressure information invariably has a disturbed and very dynamic character because it presents high frequency oscillations, which are difficult to follow using electronic control units with limited calculation capacities. Thus, it is not possible in practice to make calculations with the information from the differential pressure sensor captured at high frequency, i.e. with a periodicity of 1 millisecond.
- the invention consists in developing a low-frequency calculation method for estimating an EGR flow rate, ie with a periodicity of about 20 milliseconds, while maintaining a level of precision equivalent to a high-frequency calculation.
- a low-frequency calculation method for estimating an EGR flow rate ie with a periodicity of about 20 milliseconds, while maintaining a level of precision equivalent to a high-frequency calculation.
- the first method consists in making a model of the total flow of the engine intake gases, on the one hand, and in determining the only air flow, on the other hand.
- the total flow can be determined by a filling model, from the pressure and the temperature in the engine intake manifold, and from a filling efficiency value which is itself a function of a set of parameters comprising at least minus the speed, the pressure in the intake manifold, and possibly other parameters such as the timing position of the intake and exhaust valves.
- the fresh air flow is determined by a flow meter. of EGR is then equal to the total inlet gas flow from which the fresh air flow is subtracted. This approach is described in particular in document US 2016/0069285, or in document FR 2938016.
- the estimate is based on knowing the total intake gas flow, which is conventionally a volumetric pump model, and the fresh air flow, which is directly measured by the sensor.
- the available accuracy of this information is d 'approximately +/- 5% for the sensor measurement and approximately +/- 3% for the total flow, which may generate inconsistent results, particularly on low EGR flow values and values in transient state.
- a second method consists in using a valve cross-section model, which generally uses the Barré de Saint-Venant equation or the “Throttle Equation” in Anglo-Saxon equivalent.
- the equation gives very precise results, if one controls the position of the valve and the pressure difference which exists at its terminals. On the other hand, it is extremely sensitive to the pressure values at the valve terminals and to the angular position of the valve, when the pressure difference is low or when the valve is close to closing.
- This cross section method is used for example in the document EP 1 416 138 with the addition of a correction map taking into account the upstream pressure, the downstream pressure and the cross section of the valve, or in the document EP 3 434 888, with the addition of a dynamic correction map depending on the positions of the valve.
- the cross section method has the disadvantage of being strongly non-linear in the very closed or very open positions of the valve.
- the pressure variations are very fast dynamic phenomena, of the order of a millisecond, which are generally filtered for use in the management of the EGR system, whose order of magnitude of the constant of time is around 10 to 20 milliseconds.
- significant errors are introduced by using filtered pressure values.
- the object of the invention is to improve the accuracy of the estimation of an EGR flow rate, in particular for use in the management of the low-frequency EGR system.
- the object of the invention is a method for calculating the flow rate of recirculation of exhaust gases at the intake of an internal combustion engine allowing the control of said engine.
- the second derivative of the Barré de Saint-Venant function applied to the average value of the expansion rate ⁇ moy is calculated using three terms obtained by applying the Barré de Saint-Venant function to the envelope values ⁇ min and ⁇ max and the average value ⁇ avg.
- the exhaust gas recirculation rate is calculated by summing a first term directly proportional to the Barré de Saint-Venant function applied to the average value of the expansion rate ⁇ moy, and a second term directly proportional to the second derivative of the Barré de Saint-Venant function applied to the mean value of the rate of expansion ⁇ moy .
- the mean value ⁇ moy can be measured at low frequency.
- FIG 3 schematically illustrates the information accessible at the EGR valves.
- the cylinders 12 are supplied with air via the intake manifold 14, or intake distributor, itself supplied by a pipe 20 provided with an air filter 22 and the compressor 18b of the turbocharger 18 of the engine 10 .
- the intake circuit Ca comprises, from upstream to downstream in the direction of air circulation:
- the compressor is associated with a bypass circuit with an intake relief valve 55 which opens in the event of sudden closure of the throttle body 30, to prevent the compressed air, located between the compressor 18b and the housing butterfly 30, does not cross the compressor 18b and does not degrade it, when for example, the driver of the vehicle suddenly lifts his foot from the accelerator pedal.
- the latter collects the exhaust gases resulting from combustion and evacuates them to the outside, via a gas exhaust duct 34 leading to the turbine 18a of the turbocharger 18 and by an exhaust line 36 mounted downstream of said turbine 18a.
- the engine 10 here comprises two partial exhaust gas recirculation circuits at the intake, called “EGR” circuits (“exhaust gas recirculation” in Anglo-Saxon terms), namely a high-pressure EGR circuit 15 and a circuit Low pressure EGR 38.
- EGR exhaust gas recirculation circuits
- Circuit 38 here a low-pressure exhaust gas recirculation circuit, called “EGR BP”, originates at a point on exhaust line 36, downstream of said turbine 18a, and in particular downstream of the system. 40 for gas pollution control and returns the exhaust gases to a point in the fresh air supply pipe 20, upstream of the compressor 18b of the turbocharger 18, in particular downstream of the flowmeter 26.
- the flowmeter 26 only measures the flow of fresh air alone.
- this recirculation circuit 38 comprises, in the direction of circulation of the recycled gases, a cooler 38a, a filter 38b, and a valve 38c intended to regulate the flow of low-pressure exhaust gases.
- the valve 38c is arranged downstream of the cooler 38a and upstream of the compressor 18b.
- the air intake valve 28 can also be used to force the circulation of a low pressure exhaust gas flow in the EGR circuit BP in the case where the depression between the exhaust circuit and the intake circuit would be insufficient. In this case, closing the valve 28 makes it possible to create a depression downstream thereof, able to suck in gases from the EGR circuit BP.
- the high pressure EGR circuit 15, called “EGR HP”, originates at a point in the exhaust circuit Ce, upstream of said turbine 18a and returns the exhaust gases to a point in the admission circuit Ca, downstream of the heat exchanger 32.
- this recirculation circuit 15 includes a valve 15a configured to regulate the flow of high pressure exhaust gases.
- the engine is associated with a fuel circuit comprising, for example, fuel inj ectors (not referenced) injecting gasoline directly into each cylinder from a fuel tank (not shown).
- the engine comprises an electronic control unit 70 configured to control the various elements of the internal combustion engine from data collected by sensors at various locations of the engine.
- the electronic control unit 70 comprises a calculation module 72, a measurement module 73 and a control module 74.
- the gas pressure downstream of the EGR valve called Paval is measured using a relative pressure sensor.
- Pressure differential ⁇ P is measured using a differential pressure sensor.
- the opening angle of the Oegr valve is measured using a position sensor placed on the electric motor which drives the valve.
- Tamont the temperature upstream of the valve, in K Pamont, the pressure upstream of the valve, expressed in Pa.
- the Barré de Saint-Venant function is expressed when the flow is non-sonic, i.e. for all the calculations that interest us, by the following expression:
- ⁇ the rate of expansion, i.e. the ratio between Pamont and Pavai, dimensionless ⁇ , the adiabatic index of gases, dimensionless r, the ratio between the perfect gas constant divided by the molar mass of the gas in question, expressed in J kg -1 K -1
- pressure information is extremely dynamic due to the acyclic behavior of an internal combustion engine. This acyclism creates strong volatilities of the differential pressure signal and by that implies strong variations on the rate of expansion ⁇ .
- the present invention corresponds to a method which consists in using the following terms of the Taylor expansion in order to complete the information available without excessively increasing the computational load.
- Figure 4 illustrates the procedure used in the conventional estimate, in order to better appreciate the contribution of the invention, the procedure of which is presented in Figure 5.
- the information of the expansion rate is captured at high frequency, either every millisecond.
- the information is filtered by taking the mean ⁇ moy at low frequency, ie every 10 milliseconds.
- the function B SV2 is then applied to the mean value ⁇ moy and the coefficient ⁇ is multiplied to obtain the estimate of the EGR flow rate.
- the information is captured at high frequency, ie every millisecond.
- the maximum ⁇ max , minimum ⁇ min and average ⁇ average values at low frequency, ie every 10 milliseconds, are then recovered.
- the function B SV2 is then applied to these three maximum values ⁇ max , minimum ⁇ min and mean ⁇ moy with a weighting of 1 ⁇ 4 for the maximum value, 1 ⁇ 2 for the mean value and 1 ⁇ 4 for the minimum value and a multiplication is carried out by the coefficient ⁇ to obtain the estimate of the EGR flow rate.
- a first step 61 the maximum and minimum values of the rate of expansion are measured, then, during the following step 62, the average value of the rate of expansion is measured.
- the method 60 further comprises a step 63 for calculating the function B SV2 applied to the average expansion rate, according to equations (2) and (4), and a step 64 for calculating the second derivative of the function B SV2 applied to the mean expansion rate, according to equation (16).
- the method 60 continues with a step 65 of calculating the average flow, according to equation (17).
- the method 60 finally comprises a step 66 of engine control, through an EGR flow setpoint Q.
- the invention proposes a method for estimating the flow of EGR used for engine control, requiring little computing resources and which can use the pressure values filtered at low frequency, with sufficient accuracy of the results.
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Analytical Chemistry (AREA)
- Exhaust-Gas Circulating Devices (AREA)
Abstract
Description
Claims
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR2111896A FR3128974B1 (fr) | 2021-11-09 | 2021-11-09 | Procédé d’estimation à basse fréquence d’un débit de gaz d’échappement recyclés à l’admission d’un moteur à combustion interne |
| PCT/EP2022/080646 WO2023083681A1 (fr) | 2021-11-09 | 2022-11-03 | Procédé d'estimation à basse fréquence d'un débit de gaz d'échappement recyclés à l'admission d'un moteur à combustion interne |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| EP4430288A1 true EP4430288A1 (fr) | 2024-09-18 |
Family
ID=80122709
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP22813512.5A Pending EP4430288A1 (fr) | 2021-11-09 | 2022-11-03 | Procédé d'estimation à basse fréquence d'un débit de gaz d'échappement recyclés à l'admission d'un moteur à combustion interne |
Country Status (3)
| Country | Link |
|---|---|
| EP (1) | EP4430288A1 (fr) |
| FR (1) | FR3128974B1 (fr) |
| WO (1) | WO2023083681A1 (fr) |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3861046B2 (ja) | 2002-11-01 | 2006-12-20 | トヨタ自動車株式会社 | 内燃機関のegrガス流量推定装置 |
| FR2872220B1 (fr) * | 2004-06-24 | 2008-10-31 | Renault Sas | Procede de commande d'un debit de gaz d'echappement recircules dans un moteur de vehicule |
| FR2934323B1 (fr) * | 2008-07-22 | 2011-12-30 | Valeo Sys Controle Moteur Sas | Procede de gestion d'un circuit de circulation de gaz d'echappement d'un moteur thermique a essence et systeme de recirculation correspondant |
| FR2938016B1 (fr) | 2008-10-30 | 2010-10-29 | Renault Sas | Procede d'estimation dynamique du debit d'air frais alimentant un moteur avec circuits egr haute et basse pression |
| FR2939475B1 (fr) * | 2008-12-09 | 2014-06-06 | Renault Sas | Procede anti-pollution avec correction de la courbe aeraulique de la vanne egr. |
| FR2979389B1 (fr) * | 2011-08-29 | 2013-08-23 | Renault Sa | Systeme et procede de commande d'un moteur a combustion interne a double recirculation de gaz d'echappement pour vehicule automobile en fonctionnement transitoire |
| JP6000309B2 (ja) | 2014-09-10 | 2016-09-28 | 三菱電機株式会社 | 内燃機関のegr流量推定装置、及び内燃機関の制御装置 |
| CN109072823B (zh) | 2016-03-25 | 2021-03-30 | 本田技研工业株式会社 | 内燃机的egr控制装置和egr控制方法 |
-
2021
- 2021-11-09 FR FR2111896A patent/FR3128974B1/fr active Active
-
2022
- 2022-11-03 EP EP22813512.5A patent/EP4430288A1/fr active Pending
- 2022-11-03 WO PCT/EP2022/080646 patent/WO2023083681A1/fr not_active Ceased
Also Published As
| Publication number | Publication date |
|---|---|
| FR3128974A1 (fr) | 2023-05-12 |
| FR3128974B1 (fr) | 2025-09-05 |
| WO2023083681A1 (fr) | 2023-05-19 |
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Owner name: HORSE POWERTRAIN SOLUTIONS, S.L.U. |