Method for determining spark advance in a controlled-ignition internal combustion engine

Abstract

The present invention relates to a method for determining an ignition advance setting value (C AA ) method, the method comprising the steps of: determining a torque setting value (Cc); determining an effective torque (Ce); determining a first ignition advance efficiency (R) based on the torque setting value (Cc) and the effective torque (Ce) in a non-micro-injection fuel injection mode; AAsmi ); determining an activation state or an inactivation state of a fuel injection mode, in which a portion of the fuel is configured to be injected by microinjection (Smi), wherein the method further comprises the steps of: determining a microinjection efficiency (Rmi); determining a microinjection efficiency (Rmi) based on the microinjection efficiency (Rmi) and the first ignition advance efficiency (Rmi); AAsmi ) Determine the ignition advance efficiency (R AAami ); According to the above determined ignition advance efficiency with micro injection (R AAami ) Determine and apply the spark advance setting value (C AA ).

Description

Technical Field

[0001] The present invention claims priority from French application No. 2007431, filed on July 15, 2020, the content (text, drawings and claims) of which is incorporated herein by reference.

[0002] The present invention relates to the field of internal combustion engines. More particularly, the present invention is directed to a method for determining spark advance in a controlled-ignition internal combustion engine. Background Art

[0003] Environmental regulations set strict limits on vehicle pollutant emissions. To control these emissions, the vehicle's internal combustion engine is connected to an exhaust line equipped with exhaust gas purification components, such as catalysts. These catalysts only become truly effective above a certain operating temperature, often referred to as the activation temperature. Above this temperature, the catalyst is said to be activated and processes the pollutants very efficiently. Conversely, below this temperature, the catalyst is not activated and processes little or no pollutants.

[0004] Therefore, in order to induce the catalyst, heat needs to be supplied to the exhaust line of the internal combustion engine. The solution to this problem is to degrade the combustion (that is, to shift the spark advance so that the ignition is retarded relative to the optimal spark setting). However, this results in reduced combustion stability and has an impact on engine performance and driver experience.

[0005] To improve combustion stability, it is known from document FR 3 064 685 A1 to distribute the injected fuel quantity between a main fuel quantity and an auxiliary quantity, the auxiliary quantity being injected after ignition of the air / main fuel mixture, approximately at combustion top dead center. However, the application of this strategy results in modifications to the overall engine efficiency and engine torque. Summary of the Invention

[0006] The object of the present invention is to overcome at least one of the above-mentioned disadvantages of the prior art.

[0007] To achieve this object, the present invention provides a method for determining an ignition advance setpoint for a controlled-ignition internal combustion engine, the method comprising the following steps:

[0008] - determine the torque setpoint,

[0009] - determine the effective torque,

[0010] - in a fuel injection mode without micro-injection, determining a first ignition advance efficiency according to the torque setpoint and the effective torque,

[0011] - determining an activation state or an inactivation state of a fuel injection mode in which a portion of the fuel is provided for injection by microinjection,

[0012] Characterized in that the method further comprises the following steps:

[0013] - Determine microinjection efficiency,

[0014] - determining a spark advance efficiency with microinjection based on the microinjection efficiency and the first spark advance efficiency,

[0015] - Determining and applying the spark advance setpoint based on the spark advance efficiency with microinjection determined above.

[0016] The technical effect thereof is that, due to the correction coefficient constituted by the microinjection efficiency, the overall efficiency of the engine and the engine torque can be adjusted.

[0017] Various additional features may be provided individually or in combination:

[0018] According to an embodiment, the first spark advance efficiency is compared with an activation threshold of an injection mode with microinjection, and the injection mode with microinjection is authorized when the first spark advance efficiency is less than the activation threshold.

[0019] According to an embodiment, the activation threshold is between 0.6 and 0.8.

[0020] According to an embodiment, the spark advance setpoint is determined based on a bijective monotonic curve relating the spark advance efficiency to the spark advance amount.

[0021] According to an embodiment, the determination of the active or inactive state of the microinjection is influenced by an additional authorization from an injection control system.

[0022] According to an embodiment, the method comprises an implementation step for implementing an injection setpoint after determining the activation state or the inactivation state of the microinjection.

[0023] The present invention also aims at an electronic computer, characterized in that it comprises acquisition and processing means for acquiring and processing by means of software instructions stored in a memory, and control means required for implementing the steps of the method according to one of the above variants.

[0024] The invention also aims at providing a controlled-ignition internal combustion engine comprising a fuel injection component and an ignition component, characterised in that the controlled-ignition internal combustion engine comprises such a computer.

[0025] The invention also aims at providing a motor vehicle, characterized in that it comprises such an engine for driving the vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Other features and advantages of the present invention will become more apparent upon reading the following detailed description of non-limiting specific embodiments of the present invention and the accompanying drawings, in which:

[0027] - Figure 1 The steps of an embodiment of the method of the present invention are schematically shown.

[0028] - Figure 2 The relationship between the spark advance efficiency and the spark advance amount is shown. DETAILED DESCRIPTION

[0029] Figure 1 The steps of an embodiment of the method of the present invention are schematically shown.

[0030] The present invention is applicable to controlled-ignition internal combustion engines (e.g., gasoline-powered engines). Such engines can be installed in motor vehicles to drive the vehicles. The method is implemented by an electronic computer (e.g., an engine computer or a dedicated computer). To this end, the computer includes acquisition and processing components for acquiring and processing software instructions stored in a memory, as well as control components required to implement the method of the present invention.

[0031] Spark advance is defined as the difference between the moment the spark is triggered and the moment the piston reaches top dead center. This advance can be quantified as the angle (in degrees) that the connecting rod makes relative to the piston axis. There is a so-called optimal spark advance, at which efficiency is maximized and the engine provides the best torque for a given consumption. When engine management is directed to require an spark advance that is delayed relative to the optimal spark advance, there is a degradation of the spark advance. The spark advance efficiency is the ratio between the efficiency of the engine at the optimal spark advance and the efficiency of the engine at another spark advance.

[0032] Refer to this Figure 1 , ignition advance setting value C AA The engine torque Ce is determined based on the driver's torque request (also referred to as the engine torque setpoint Cc) and an estimate of the effective engine torque Ce. The driver's torque request Cc is typically represented by an accelerator pedal press. The estimated engine torque Ce is derived based on the amount of air in the cylinders, as well as the cycle efficiency and richness.

[0033] In the injection mode with microinjection, a portion of the fuel is provided for injection via microinjection. The use of microinjection results in a modification of the overall engine efficiency. Thus, with microinjection activated, the engine torque evolves without any additional actions being performed. Therefore, when setting the spark advance setpoint C AA This evolution of the engine's efficiency needs to be taken into account when designing the engine. This consideration allows for improved engine performance through better tracking of the torque and for optimization of pollutant emissions.

[0034] To this end, the invention comprises calculating a specific microinjection efficiency which is subsequently used to determine the spark advance setpoint. The microinjection efficiency is physically dependent on speed, engine load, advance degradation and main injection richness.

[0035] In this embodiment, the first ignition advance efficiency R AAsmi Therefore, the first ignition advance efficiency R is determined based on the ratio between the torque setting value Cc and the effective engine torque Ce. AAsmi This corresponds to the spark advance efficiency in the case of an engine in a non-micro-injection fuel injection mode.

[0036] In order not to allow activation of the microinjection in engine operating conditions that are unfavorable to the engine (e.g. too delayed injection) with the risk of the fuel jet impinging on the piston when the piston of the engine is too high, the first ignition advance efficiency R AAsmi With the activation threshold S RAA Make a comparison.

[0037] Therefore, if the first ignition advance efficiency R AAsmi Less than the activation threshold S RAA , the activation of the microinjection is authorized. Activation threshold S RAA The activation threshold S is of the order of 60% to 80% of the spark advance efficiency (that is, between 0.6 and 0.8). RAA The activation threshold S RAA May be stored in a map included in memory.

[0038] Based on the result of the comparison, the method determines the microinjection status Smi (active or inactive).

[0039] If the microinjection state Smi is active, the value of the microinjection efficiency Rmi is taken into account to correct the first ignition advance efficiency R AAsmi .

[0040] If the microinjection state Smi is inactive, the value 1 is used in order to preserve the first ignition advance efficiency RAAsmi The value of .

[0041] The determination of the active or inactive state SMI for the microinjection can also be configured to be influenced by additional authorizations from an injection management function for managing the injection system INJ, which checks whether the conditions for carrying out the microinjection are acceptable from the perspective of the injection system alone. For example, there is a check on the total fuel mass to be injected. This total fuel mass must be greater than a minimum threshold in order to be able to be divided into two parts (i.e., the main injection and the microinjection).

[0042] Provision may further be made for sending the microinjection status Smi towards a function BDC which translates the decision to carry out or not to carry out said microinjection into an injection.

[0043] The microinjection efficiency Rmi can be determined in advance for each engine operating point and stored in a map that establishes this efficiency based on the engine's operating parameters. This microinjection efficiency translates into a reduction in engine torque due to the portion of fuel used for the microinjection that does not contribute to generating engine torque. The microinjection efficiency Rmi is on the order of approximately 85% to 90%.

[0044] Therefore, the first ignition advance efficiency R AAsmi Corrected by dividing by the microinjection efficiency Rmi to define the microinjection advance efficiency set value R AAami The microinjection advance efficiency setpoint is then used to calculate the ignition advance setpoint C AA .

[0045] Ignition advance setting value C AA Based on the microinjection advance efficiency R AAami By establishing the ignition advance efficiency R AA The monotonic curve C of the bijective relationship between the applied spark advance AA R-AA (Similarly Figure 2 OK.

[0046] Due to this correction, the applied spark advance is closer to the optimal spark advance than the spark advance when the fuel is injected according to the injection mode without microinjection.

[0047] Thanks to this strategy, the activation of the micro-injection is transparent to the torque produced by the engine. It is compensated by a smaller reduction in ignition advance to maintain constant torque, thus no longer affecting the customer's experience in the vehicle.

[0048] The strategy provided enables precise management of the engine torque when the microinjection is used. This precise management ensures, in particular, optimal performance of drivability and optimal performance of pollutant emissions.

Claims

1. A method for determining an ignition advance setting value (C AA ), the method comprising the following steps: - determine the torque setpoint (Cc), - determine the effective torque (Ce), - In the case of the non-micro-injection fuel injection mode, determining the first ignition advance efficiency (R AAsmi ), - determining an active or inactive state of a fuel injection mode, in which a portion of the fuel is provided for injection by microinjection (Smi), Characterized in that the method further comprises the following steps: - Determination of microinjection efficiency (Rmi), - Based on the microinjection efficiency (Rmi) and the first ignition advance efficiency (R AAsmi ) Determine the ignition advance efficiency (R AAami ), - Based on the above determined ignition advance efficiency with micro-injection (R AAami ) Determine and apply the spark advance setting value (C AA ).

2. The method according to claim 1, characterized in that The first ignition advance efficiency (R AAsmi ) and the activation threshold (S RAA ) is compared, when the first ignition advance efficiency (R AAsmi ) is less than the activation threshold (S RAA ), the microinjection mode is authorized.

3. The method according to claim 2, characterized in that The activation threshold is between 0.6 and 0.

8.

4. The method according to any one of the preceding claims, characterized in that The ignition advance setting value (C AA ) Based on the ignition advance efficiency (R AA ) is determined by a bijective monotonic curve relating ignition advance (AA).

5. The method according to any one of claims 1 to 3, characterized in that The determination of the active or inactive state of the microinjection (Smi) is influenced by an additional authorization which comes from the injection control system (INJ).

6. The method according to any one of claims 1 to 3, characterized in that The method comprises an implementation step for implementing a injection set value (BDC) after determining the activation state or the inactivation state of the microinjection (Smi).

7. An electronic computer, characterized in that: The electronic computer comprises acquisition and processing means for acquisition and processing by means of software instructions stored in a memory and control means required for implementing the steps of the method according to any one of the preceding claims.

8. A controlled ignition internal combustion engine comprising a fuel injection component and an ignition component, characterized in that: The controlled-ignition internal combustion engine includes the electronic computer according to claim 7.

9. A motor vehicle, characterized in that: The motor vehicle includes a controlled-ignition internal combustion engine according to claim 8 to drive the motor vehicle.

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