METHOD FOR AUTHORIZING THE STARTING OF AN INTERNAL COMBUSTION ENGINE

Abstract

The invention relates to a method for authorizing the starting of an internal combustion engine comprising the following steps: a step of measuring the control value of the air pump (E1); a step of measuring the control value of the valve (E2); a step of measuring the temperature (E3) at the valve; a step of calculating the gas flow rate at the air pump (E4); a step of calculating the gas flow rate at the valve (E5); a step of calculating the pressure (E6) at the internal combustion engine; and a step of starting said internal combustion engine (E7). The invention also relates to a computer program, an internal combustion engine, and a vehicle comprising such an internal combustion engine. Abstract figure: Fig. 1

Description

Title of the invention: METHOD FOR AUTHORIZING THE STARTING OF A HEAT ENGINE

[0001] The invention relates to the field of thermal engines, and more particularly to the polluting emissions emitted by these engines during start-up.

[0002] Known from the prior art is a patent application US2009025689 which describes a method for determining the volatility of the fuel during a cold start of an internal combustion engine of a motor vehicle. The objective of the invention is to minimize the quantity of fuel to be injected into said engine to start it when the outside temperatures are below 10 degrees Celsius. Indeed, when the outside temperature drops, the non-volatile parts of the fuel remain liquid and are evacuated by the exhaust system without having participated in the combustion. To compensate for this loss, it is necessary to enrich the fuel injection, that is to say to increase the quantity of fuel to be injected. However, this leads to overconsumption of fuel by the engine of said vehicle, and consequently, an increase in the quantity of polluting gases released into the environment by said vehicle.The first step in implementing said method is to determine an enrichment percentage based on a stored value representing the volatility of the fuel. The second step is to start the engine using the previously determined enrichment percentage. The third step is to determine a predictive value for the starting quality, i.e., a fictitious value determined before starting. The fourth step is to determine a measured value for the starting quality when increasing the engine speed. The fifth step is to determine a correction value for said stored value by comparing the measured value with the predictive value for the starting quality. In a sixth step, the stored value for the volatility is corrected by applying said correction value.Thus, in this way, only the amount of fuel necessary for the proper functioning of the engine is injected into said engine. In this way, said engine does not consume more than necessary and the emissions of polluting gases are reduced. However, a disadvantage remains. The volatile part of the fuel remains unchanged and, therefore, fuel consumption is always higher than it would be if all of the injected fuel were useful for combustion. Thus, the emissions of polluting gases are always higher than they should be.

[0003] The objective of the present invention is to overcome this drawback by proposing a faster and more hassle-free method for authorizing the start of a thermal engine. impact the secondary air injection system allowing the reduction of the emission rate of polluting gases.

[0004] To achieve this objective, the invention proposes a method for authorizing the start of a heat engine comprising an air filter and a secondary air injection system, said air filter comprising a first pressure sensor, said secondary air injection system comprising an air pump, a second pressure sensor, a temperature sensor and a valve, said heat engine comprising a means for measuring a control value of said air pump, a means for measuring a control value of said valve, a means for measuring a temperature value at said valve, a means for calculating a gas flow rate value at the air pump, a means for calculating a gas flow rate value at the valve, a means for calculating a pressure value at said heat engine and a means for starting said heat engine, said method comprises the following steps: - a step of measuring the air pump control value; - a step of measuring the valve control value; - a step of measuring the temperature value at the valve; - a step of calculating the gas flow value at the air pump; - a step of calculating the gas flow rate value at the valve; - a step of calculating the pressure value at the level of the thermal engine; - a step of starting said heat engine when, during a predetermined period of time, said air pump control value is less than a first threshold value, said valve control value is less than a second threshold value, said gas flow rate value to the air pump is less than a third threshold value, said gas flow rate value to the valve is less than a fourth threshold value and said pressure value is less than a fifth threshold value.

[0005] Thanks to the invention, the starting of said vehicle is faster. In addition, starting is safer because it is ensured that the secondary air injection system is inactive.

[0006] Preferably, said step of calculating a value of the gas flow rate at the valve is obtained by the following formula: Q — 5* *Cfe[ ) with Q being the value of the gas flow rate at the valve; S being a section value of said valve; PO being the pressure value in said secondary air injection system, obtained by said second pressure sensor; PO being the temperature value at the valve; Cfe being a coefficient of gas pressure loss when passing through said valve, based on said calculation of the ratio of said pressure value in said air filter obtained by the first pressure sensor and said pressure value in said secondary air injection system obtained by the second pressure sensor; P being said pressure value in the air filter obtained by said first pressure sensor.

[0007] Advantageously, said step of calculating the pressure at the level of the heat engine is carried out by calculating the ratio of a pressure value in said air filter obtained by said first pressure sensor and a pressure value in said secondary air injection system obtained by said second pressure sensor.

[0008] Advantageously, said air pump comprising a rotation speed sensor, during said step of calculating the gas flow rate value at the air pump, the gas flow rate value at the air pump is determined by the data from a graph comprising the characteristic curves of the flow rate generated by the air pump as a function of the rotation speed of said air pump and as a function of the pressure at said heat engine.

[0009] Advantageously, during said step of calculating the gas flow rate value at the air pump, the gas flow rate value at the air pump is determined using data from a graph comprising the characteristic curves of the flow rate generated by the air pump as a function of the control value of the air pump and as a function of the pressure at said heat engine.

[0010] Advantageously, during said step of starting said heat engine, the predetermined time period is less than 10 seconds.

[0011] Preferably, during said step of starting said heat engine, the predetermined time period is less than one second.

[0012] Thus, the thermal engine can be started quickly.

[0013] Furthermore, the invention relates to a computer program comprising instructions which, when the program is executed by a computer, cause the latter to implement the steps of said method for authorizing the start of a heat engine as previously described.

[0014] Furthermore, the invention relates to a heat engine implementing the method for authorizing the start of a heat engine previously described.

[0015] Finally, the invention relates to a motor vehicle comprising the heat engine mentioned above.

[0016] The invention will be further detailed by the description of a non-limiting embodiment, and on the basis of the appended figure illustrating the invention, in which [Fig.l] schematically illustrates, in the form of a logic diagram, a method for authorizing the start of a thermal engine.

[0017] [Fig.l] is schematically illustrated in the form of a flowchart, a method for starting a heat engine. The heat engine comprises an air filter and a secondary air injection system. The secondary air injection system is a system for reducing pollutant gas emissions during cold starting of said heat engine. The air filter comprises a first pressure sensor. The secondary air injection system comprises an air pump. The air pump of the secondary air injection system makes it possible to send air to an electric heating grid located near the engine. The aim is to blow hot air towards a catalyst to increase its temperature before starting the engine so that the catalyst is capable of treating the pollutant emissions as soon as the engine is started.Furthermore, the secondary air injection system comprises a second pressure sensor, a temperature sensor and a valve. The valve is used to regulate the flow rate of air circulating in said secondary air injection system. The heat engine comprises a means for measuring a command value of said air pump and a means for measuring a command value of said valve. The command value, whether assigned to the air pump or to the valve, corresponds to a unitless value determining the operating state of said air pump or said valve. For example, said valve command value is between 0 and 1, 0 being the minimum value for which the valve is fully closed and 1 being the maximum value for which the valve is fully open.Intermediate control values ​​of said valve are possible, for example for a value of 0.5 said valve is half-open, reducing by half the quantity of air which can pass through said valve compared to its capacity when the latter is fully open. The heat engine comprises a means for measuring a temperature value located at said valve. Preferably, said means for measuring a temperature value is a temperature sensor. In addition, said heat engine comprises a means for calculating a gas flow rate value at said air pump, a means for calculating a gas flow rate value at the valve, a means for calculating a pressure value at said heat engine and a means for starting said heat engine. During a step of measuring the control value of the air pump E1, the control value of said air pump is measured in order to provide information on the state in which said air pump is found.During a step of measuring the control value of the valve E2, the control value of said valve is measured in order to know in which configuration said valve is located. Indeed, said valve can be open, closed or semi-open for example. During a step of measuring the temperature value E3, the temperature is measured by the means for measuring the temperature value, which is preferably a temperature sensor. During a step of calculating the value of . gas flow rate at the air pump E4, the gas flow rate passing through said air pump is calculated. In an alternative embodiment, if said air pump is equipped with a rotation speed sensor, the flow rate passing through said air pump is determined by the data from a graph comprising the characteristic curves of the flow rate generated by the air pump as a function of the rotation speed of said air pump and as a function of the pressure at said heat engine. In another embodiment, the data comes from a graph comprising the characteristic curves of the flow rate generated by the air pump as a function of the control value of said air pump and as a function of the pressure of said heat engine. During a step of calculating the gas flow rate value at the valve E5, the gas flow rate passing through said valve is calculated from the previously collected values.Preferably, said value of the gas flow rate at valve Q is obtained by the following formula: . ~ pn ( p \with 5 being a section value of said valve; PO being the pressure value in said secondary air injection system, obtained by said second pressure sensor; TO being the temperature value at the valve; Cf e being a gas pressure drop coefficient when passing through said valve, based on said calculation of the ratio of said pressure value in said air filter obtained by the first pressure sensor and said pressure value in said secondary air injection system obtained by the second pressure sensor; P being said pressure value in the air filter obtained by said first pressure sensor. During a step of calculating the pressure value E6, the pressure present within said heat engine is calculated.Preferably, said step of calculating the pressure value E6 is carried out by calculating the ratio of a pressure value P in said air filter obtained by said first pressure sensor and a pressure value in said secondary air injection system obtained by said second pressure sensor. During a step of starting said heat engine E7, non-activity of said secondary air injection system is verified.The secondary air injection system is considered to be in an inactive state when said inactivity is detected when, during a predetermined period of time, said air pump command value is less than a first threshold value, said valve command value is less than a second threshold value, said air pump gas flow rate value is less than a third threshold value, said valve gas flow rate value is less than a fourth threshold value, and said pressure value is less than a fifth threshold value. Each threshold value can be specifically predetermined according to different situations. For example, in a first case of activating the secondary air injection strategy to accelerate the heating of said catalyst before starting the engine such as pre . previously explained. This is the most common use case. In another example, in a second case of interruption of a draining phase of the secondary air injection circuit, the engine being stopped. In the second case, the air pump and the valve allow the injection of air into said circuit in order to expel the exhaust gases. If a user wishes to start the vehicle at that moment, the draining is interrupted. Advantageously, said predetermined period of time is less than 10 seconds, preferably less than 1 second. When all of the previously mentioned conditions are met, the heat engine is then authorized to start. The emissions of polluting gases emanating from the start of said heat engine are then reduced. The invention also relates to a heat engine implementing the method for authorizing the start of a heat engine described above and to a motor vehicle comprising such a heat engine.

Claims

Claims

1. Method for authorizing the start of a heat engine comprising an air filter and a secondary air injection system, said air filter comprising a first pressure sensor, said secondary air injection system comprising an air pump, a second pressure sensor, a temperature sensor and a valve, said heat engine comprising a means for measuring a control value of said air pump, a means for measuring a control value of said valve, a means for measuring a temperature value at said valve, a means for calculating a gas flow rate value at the air pump, a means for calculating a gas flow rate value at the valve, a means for calculating a pressure value at said heat engine and a means for starting said heat engine,characterized in that said method comprises the following steps: - a step of measuring the air pump control value (E1) - a step of measuring the valve control value (E2); - a step of measuring the temperature value (E3) at the valve; - a step of calculating the gas flow rate value at the air pump (E4); - a step of calculating the gas flow rate value at the valve (E5); - a step of calculating the pressure value (E6) at the heat engine; - a step of starting said heat engine (E7) when, for a predetermined period of time, said air pump control value is less than a first threshold value, said valve control value is less than a second threshold value, said gas flow rate value at the air pump is less than a third threshold value,said gas flow rate value at the valve is less than a fourth threshold value and said pressure value is less than a fifth threshold value.,

2. Method according to claim 1 characterized in that said step of calculating a value of the gas flow rate at the valve (E5) is obtained by the following formula: e = S*Æ*c / e[i) With Q being the value of the gas flow rate at the valve; S being a section value of said valve; PO being the pressure value in said secondary air injection system, obtained by said second pressure sensor; PO being the temperature value at the valve; Cfe being a coefficient of gas pressure loss when passing through said valve, based on said calculation of the ratio of said pressure value in said air filter obtained by the first pressure sensor and said pressure value in said secondary air injection system obtained by the second pressure sensor; P being said pressure value in the air filter obtained by said first pressure sensor.

3. Method according to claim 1 or 2 characterized in that said step of calculating the pressure at the level of the heat engine (E6) is carried out by calculating the ratio of a pressure value in said air filter obtained by said first pressure sensor and a pressure value in said secondary air injection system obtained by said second pressure sensor.

4. Method according to any one of claims 1 to 3 characterized in that, said air pump comprising a rotation speed sensor, during said step of calculating the gas flow rate value at the air pump (E4), the gas flow rate value at the air pump is determined by the data from a graph comprising the characteristic curves of the flow rate generated by the air pump as a function of the rotation speed of said air pump and as a function of the pressure at said heat engine.

5. Method according to any one of claims 1 to 3 characterized in that, during said step of calculating the gas flow rate value at the air pump (E4), the gas flow rate value at the air pump is determined by the data from a graph comprising the characteristic curves of the flow rate generated by the air pump as a function of the control value of the air pump and as a function of the pressure at the said heat engine.

6. Method according to any one of claims 1 to 5 characterized in that, during said step of starting said heat engine (E7), the predetermined period of time is less than 10 seconds.

7. Method according to claim 6 characterized in that, during said step of starting said heat engine (E7), the predetermined period of time is less than one second.

8. Computer program comprising instructions which, when the program is executed by a computer, cause the latter to implement the steps of said method for authorizing the start of a motor vehicle with a thermal engine according to any one of claims 1 to 7.

9. Heat engine implementing the method for authorizing the start of a heat engine according to any one of claims 1 to 7.

10. Motor vehicle comprising a heat engine according to claim 9.

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