Method for determining an air volume of an air reserve for an internal combustion engine of a vehicle

Abstract

One aspect of the invention relates to a method 100 for determining an air volume of an air reserve for an internal combustion engine fitted to a motor vehicle, the method 100 being characterized in that, when a request to heat an exhaust catalytic converter of the vehicle is detected, it executes the steps of: determining 101 a first maximum air volume for the air reserve according to a determined engine speed, a determined torque setpoint and a determined coolant temperature; injecting 103 the first maximum air volume stored in an air reserve into the engine; when the amount of energy accumulated in the catalytic converter reaches an energy amount threshold, determining a second air volume for the air reserve that is less than the first maximum air volume; decreasing the maximum air volume stored in the air reserve until the second air volume is reached.

Description

DESCRIPTION TITLE: METHOD FOR DETERMINING THE AIR VOLUME OF AN AIR RESERVOIR FOR AN INTERNAL COMBUSTION ENGINE OF A VEHICLE

[0001] The present invention claims priority from French application No. 2405461 filed on 28.05.2024, the content of which (text, drawings and claims) is incorporated herein by reference.

[0002]

[0003] The present invention relates generally to the reduction of pollutant emissions from internal combustion engines. The technical field of the invention relates more particularly to the control of an air reservoir to increase the temperature of an exhaust catalyst.

[0004] Currently, within an increasingly restrictive legislative framework and with a concern for environmental preservation, technical solutions are being sought to improve the operation of internal combustion engines, particularly to reduce the level of pollutants contained in the exhaust gases that are released by the engines into the atmosphere.

[0005] To reduce these polluting emissions, an internal combustion engine comprises a selected number of cylinders, each forming a combustion chamber capable of burning a mixture of air and fuel. This combustion is supervised by an engine control unit (ECU), configured to adjust, via actuators, various engine operating parameters that influence combustion. These parameters include, for example, regulating the amount of air admitted into the cylinders, the mass of fuel injected, and the ignition timing to trigger combustion.

[0006] Exhaust gases, and more specifically pollutants such as carbon monoxide, nitrogen oxides and unburned hydrocarbons, resulting from combustion are usually treated using an exhaust catalyst.

[0007] This catalyst operates optimally at a temperature of around 400°C. However, its performance is significantly reduced at lower temperatures. ambient temperature, just after the engine is started from cold. As a result, the majority of pollutants released into the atmosphere are emitted during this time.

[0008] With the arrival of new standards concerning motor vehicles, notably Euro7, it was decided that this situation could not continue.

[0009] When the exhaust catalyst is at ambient temperature, for example during engine start-up, additional air is injected into the engine to reach its optimal temperature of 400°C. This increased oxygen supply effectively contributes to raising the exhaust temperature and, consequently, the catalyst temperature.

[0010] To achieve this, the intake air throttle is controlled to store a predetermined volume of air in an air reservoir. This predetermined volume of air stored in the air reservoir is then injected into the engine cylinders to increase the oxygen supply to the engine, and therefore the exhaust gas temperature.

[0011] We also know from document FR-A1-3122901, a control strategy allowing to accelerate the heating of catalyst by using the vacuum pump depression of a braking system to increase the mass of air of the exhaust catalyst.

[0012] The invention offers a different solution, by proposing a method to accelerate the heating of an exhaust catalyst which is easy to implement.

[0013] In this context, the invention relates, in its broadest sense, to a method for determining the volume of air in an air reservoir for an internal combustion engine equipping a motor vehicle, the vehicle having an exhaust catalytic converter, the method being remarkable in that it performs, via vehicle control means, when a demand for catalyst heating is detected by the control means, the following steps: Determine a first maximum air volume for the air reserve as a function of a given engine speed, a given torque setpoint and a given coolant temperature; Inject the first maximum volume of air into the air reservoir; Inject the first maximum volume of air stored in the air reservoir into the engine; Determine the amount of energy stored in the catalyst; When the amount of energy accumulated in the catalyst reaches a threshold of energy quantity, determine a second volume of air for the air reserve that is less than the first maximum air volume; Decrease the maximum volume of air stored in the air reservoir until it reaches the second air volume.

[0014] Thanks to the process according to the invention, at the start of the internal combustion engine, the exhaust catalyst has little to no stored energy. This enthalpy boost, created by a maximum volume of air stored in the air reservoir, allows the catalyst temperature to rise rapidly, thus increasing the energy stored in the catalyst as quickly as possible. When the stored energy reaches a predetermined threshold, reflecting, for example, a catalyst temperature of 400°C, the process reduces the volume of air in the air reservoir to return to a nominal volume that maintains the catalyst's optimal operating temperature. This solution requires no additional components. In fact, it is sufficient to control the throttle body of the internal combustion engine to regulate the volume of air stored in the air reservoir. This alternative solution is therefore inexpensive and easy to implement.

[0015] In addition to the characteristics mentioned in the preceding paragraph, the process according to this aspect of the invention may have one or more complementary characteristics from among the following, considered individually or according to all technically possible combinations.

[0016] According to a non-limiting aspect of the invention, the amount of energy accumulated in the catalyst is determined by the following formula: E = fmx Cp x ( T1- r0) With E = Quantity of energy stored in the catalyst; m = Mass of air at the exhaust; Cp = Specific heat capacity of air; To = Catalyst temperature when a catalyst heating demand is detected; Ti = Temperature of the catalyst during the step to determine the amount of energy accumulated in the catalyst.

[0017] According to a non-limiting aspect of the invention, the first maximum air volume is determined by the product of an initial air volume and a coefficient.

[0018] According to a non-limiting aspect of the invention, The initial air volume is determined by means of an initial map providing initial air volume values ​​as a function of engine speed values ​​and torque setpoint values; The coefficient is determined by means of a second map providing coefficient values ​​as a function of coolant temperature values.

[0019] According to a non-limiting aspect of the invention, the second volume of air is determined by applying a percentage reduction to the first maximum volume of air.

[0020] According to a non-limiting aspect of the invention, the percentage reduction is determined by means of a third mapping providing percentage reduction values ​​as a function of values ​​of the amount of energy accumulated in the catalyst.

[0021] According to a non-limiting aspect of the invention, the volume of air stored in the air reserve is regulated by controlling, via the control means, an air intake butterfly valve included in the internal combustion engine.

[0022] Another aspect of the invention relates to a motor vehicle comprising an internal combustion engine, an exhaust catalyst, an air reservoir and control means configured to carry out the steps of the process according to any one of the aforementioned aspects of the invention.

[0023] According to a non-limiting aspect of the invention, the catalyst is of the three-way type.

[0024] Another aspect of the invention relates to a computer program product downloadable from a communication network and / or saved on a medium computer-readable and / or processor-executable. The computer program product includes program code instructions for implementing the method according to any one of the aforementioned aspects of the invention, when the program is executed on a computer.

[0025] The invention and its various applications will be better understood by reading the following description and examining the accompanying figures.

[0026] [Fig. 1] illustrates, schematically, a vehicle according to a non-limiting embodiment of the invention.

[0027] [Fig. 2] illustrates a step diagram of a process for determining the volume of air in an air reservoir for an internal combustion engine equipping a vehicle such as that shown in Figure 1.

[0028] The figures are presented for illustrative purposes only and are in no way limiting to the invention.

[0029] Unless otherwise specified, the same element appearing on different figures has a unique reference.

[0030] Figure 1 illustrates a motor vehicle. Vehicle 1 includes, in particular, from upstream to downstream of the airflow, A butterfly valve 2; An air reserve 3, also called a plenum; An internal combustion engine 4; and A 5-way exhaust catalyst, for example of the three-way type.

[0031] The vehicle 1 further includes control means 6. These control means 6 are configured to perform the steps of a process 100 for determining the volume of air in the air reserve 3 of the internal combustion engine 4 equipping the motor vehicle 1 such as that illustrated in Figure 2.

[0032] When a demand for heating of the exhaust catalyst 5 is detected by the control means 6, for example during the starting of the internal combustion engine 4, the process 100 executes a step 101 to determine a first maximum air volume for the air reservoir 3 as a function of a determined engine speed, for example in revolutions per minute, and a determined torque setpoint, for example in newton meter, and a specific coolant temperature, for example in °C.

[0033] As a non-limiting example, this torque setting corresponds to the accelerator pedal travel of vehicle 1, measured by means of a travel sensor. This torque setting reflects the user's desired vehicle acceleration.

[0034] In addition, according to a non-limiting embodiment, the coolant temperature can be measured by a temperature sensor.

[0035] The first volume of air is maximized in order to provide the maximum volume of oxygen to the engine 4, enabling the exhaust gas temperature to increase as quickly as possible, and consequently the temperature of the exhaust catalyst 5, without disrupting the operation of the engine 4.

[0036] According to a non-limiting aspect of the invention, the first maximum air volume is determined by the product of an initial air volume and a coefficient.

[0037] In a non-limiting embodiment, the initial air volume is determined by means of a first map C1. This first map C1 provides initial air volume values ​​as a function of engine speed and torque setpoint values. Thus, from a given engine speed and torque setpoint, it is possible to select the initial air volume of the product.

[0038] In a non-limiting embodiment, the product coefficient is determined by means of a second map C2. This second map C2 provides coefficient values ​​as a function of coolant temperature values. Thus, from a determined internal combustion engine coolant temperature 4, it is possible to select the product coefficient.

[0039] The process 100 also includes a step of injecting 102, by means of the throttle body 2 controlled by the control means 6, the first maximum volume of air into the air reservoir 3, then a step of injecting 103 the first maximum volume of air stored in the air reservoir 3 into the engine 4.

[0040] The process 100 also includes a step of determining 104 an amount of energy accumulated in the exhaust catalyst 5.

[0041] The amount of energy stored in the exhaust catalyst 5 can be determined by the following formula: E = fmx Cp x ( T - T o ) With E = Quantity of energy stored in the exhaust catalyst 5; m = Mass of air at the exhaust; Cp = Specific heat capacity of air; To = Temperature of the exhaust catalyst 5 when a demand for heating of the catalyst 5 is detected; Ti = Temperature of the exhaust catalyst 5 during the determination step 104 of the amount of energy accumulated in the exhaust catalyst 5.

[0042] When the amount of energy accumulated in the exhaust catalyst 5 reaches an energy quantity threshold, the process 100 includes a step of determining 105 a second volume of air for the air reserve 3 lower than the first maximum air volume.

[0043] According to a non-limiting embodiment, the second air volume is determined by applying a percentage reduction to the first maximum air volume. For example, the percentage reduction is determined by means of a third map C3 that provides percentage reduction values ​​based on the amount of energy stored in the exhaust catalyst 5. Thus, from the amount of energy stored in the catalyst 5 determined in step 104, it is possible to select the percentage reduction.

[0044] Therefore, process 100 includes a step of reducing 106, by controlling the throttle body 2 via the control means 6, the maximum volume of air stored in the air reserve 3 until the second air volume is reached.

[0045] Then, this second volume of air stored in the air reservoir 3 is injected into the cylinders of the internal combustion engine 4 in order to reduce the oxygen supply in the internal combustion engine 4, and therefore consequently to stop the temperature increase of the exhaust catalyst and maintain it at an optimal operating temperature

[0046] Indeed, in order to avoid an excessive temperature rise in the exhaust catalyst 5, the second volume of air determined by the process 100 according to the invention is less than the first maximum volume of air initially planned to rapidly increase the temperature of the exhaust catalyst 5.

Claims

DEMANDS

1. A method (100) for determining the volume of air in an air reservoir (3) for an internal combustion engine (4) equipping a motor vehicle (1), said vehicle (1) comprising an exhaust catalyst (5), said method (100) being characterized in that it performs, via control means (6) of said vehicle (1), when a heating demand for said catalyst (5) is detected by said control means (6), the steps of: - Determine (101) a first maximum air volume for said air reserve (3) as a function of a determined engine speed, a determined torque setpoint and a determined coolant temperature; - Inject (102) the said first maximum volume of air into the said air reserve (3); - Inject (103) said first maximum volume of air stored in said air reserve (3) into said engine (4); - Determine (104) a quantity of energy accumulated in the catalyst (5); - When the said quantity of energy accumulated in the said catalyst (5) reaches a threshold of quantity of energy, determine (105) a second volume of air for the said air reserve (3) less than the said first maximum volume of air; - Decrease (106) the said maximum volume of air stored in the said air reserve until the said second volume of air is reached.

2. A method (100) according to the preceding claim, characterized in that the amount of energy stored in the catalyst (5) is determined by the following formula - With - E = Quantity of energy stored in the catalyst (5); - m = Mass of air at the exhaust; - Cp = Specific heat capacity of air; - To = Temperature of the catalyst (5) when a demand for heating of the catalyst (5) is detected; - Ti = Temperature of the catalyst (5) during the step of determining (104) a quantity of energy accumulated in said catalyst (5). [Claims] A method (100) according to any one of the preceding claims, characterized in that the first maximum air volume is determined by the product of an initial air volume and a coefficient.

4. A method (100) according to the preceding claim, characterized in that: - The initial air volume is determined by means of a first map (C1) providing initial air volume values ​​as a function of engine speed values ​​and torque setpoint values; - The coefficient is determined by means of a second map (C2) providing coefficient values ​​as a function of coolant temperature values. [Claims] Method (100) according to any one of the preceding claims, characterized in that the second air volume is determined by applying a percentage reduction to the first maximum air volume.

6. Method (100) according to the preceding claim, characterized in that the percentage reduction is determined by means of a third mapping (C3) providing percentage reduction values ​​as a function of values ​​of the amount of energy accumulated in the catalyst (5).

7. Method (100) according to any one of the preceding claims, characterized in that the volume of air stored in the air reservoir (3) is regulated by controlling, via the control means (6), an air intake butterfly valve (2) which comprises the internal combustion engine (4). [Claims] A motor vehicle (1) comprising an internal combustion engine (4), an exhaust catalyst (5) and an air reservoir (3), said vehicle (1) being characterized in that it comprises control means (6) configured to execute the steps of the process (100) according to any one of the preceding claims.

9. Vehicle (1) according to the preceding claim, characterized in that the catalyst (5) is of the three-way type.

10. Product: Computer program downloadable from a communication network and / or stored on a computer-readable medium and / or executable by a processor, characterized in that it comprises program code instructions for implementing the method (100) according to any one of claims 1 to 7, when the program is executed on a computer.

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