FR3139366A1 - Method and system for controlling engine torque of an internal combustion engine - Google Patents

Abstract

Method for controlling engine torque of an engine comprising: - a system for regulating an incoming air flow (110), and - an ignition system (130), method according to which - from a request of torque (TQ_REQ), an air flow setpoint value (MAF_SP) is determined, - from MAF_SP a position setpoint value (TPS_SP) of a mobile control member of the regulation system (110) is determined, - the incoming air flow (MAF) and the position of the mobile control member (TPS) are measured, - a quantity of fuel to be injected (QTF) is calculated from MAF, and - an angle d The ignition (IGN_ANG) is calculated from: - - of MAF if the difference between TPS and TPS_SP is greater than a predetermined position difference (EPS), and - - of MAF_SP if the difference between TPS and TPS_SP is less than EPS. Abstract Figure: Figure 2

Description

Method and system for controlling engine torque of an internal combustion engine

The present disclosure relates to a method and a system for controlling engine torque of an internal combustion engine.

The technical field of the present invention is thus the field of engine control for an internal combustion engine. The present disclosure is intended more particularly for non-automotive applications and concerns rather but not exclusively small engines, used for example on motorcycles. Such a motor can also be used for another motor application (mower or other mobile motorized tool, etc.).

The present disclosure concerns even more particularly internal combustion engines in which a flap, called a butterfly, controls the flow of air entering the engine, said butterfly being controlled in a controlled manner, most often electrically. In such an engine, the user's command on a pedal called an accelerator pedal, or a handle, or a joystick, or the like, is translated into a torque request (request) and a control and management system comes then determine setpoint values concerning for example the opening angle of the throttle so that the motor provides the torque corresponding to the user's torque request.

Conventionally, the torque request is translated, by an electronic management and control unit or controller, into an air flow setpoint entering the engine by an inverse torque model and in turn the flow setpoint d The air is translated into a position (or angle) instruction for opening the throttle by an inverse air flow model. In addition, conventionally, a direct model is used by the controller for fuel injection and ignition: from a certain number of data obtained using sensors, such (non-exhaustive illustrative list) the throttle opening angle, the engine speed, the intake pressure, the temperature, etc. an estimated air flow rate of the air which has actually entered the engine is calculated. This value of the air flow will make it possible to determine, on the one hand, the quantity of gasoline to be supplied to the engine to achieve combustion and, on the other hand, the maximum torque that the engine can provide. Depending on the maximum available torque and the requested torque (request), an ignition angle is determined. If the available torque is greater than the torque actually requested, an ignition advance reduction will be carried out to obtain the torque setpoint value.

We notice that a large number of calculations are necessary and that maps are used. A small error in calculations and/or maps can lead to a loss of engine efficiency of the order of a percent. This corresponds to an increase in consumption of the same order of magnitude compared to optimized consumption.

In the automotive field, we constantly compare the estimated air flow and a measured air flow and a correction is made to the throttle opening to make these values coincide. In this way, errors between the estimated flow and the measured flow are compensated. A motor vehicle generally has an intake manifold of relatively large volume. Thanks to this large volume collector, the controller can adjust the position of the throttle quickly and even during a transient regime, the corrections made are insensitive to the driver and allow optimized operation as soon as a stationary regime is found.

For non-automotive applications, the transient phases are generally briefer and the controller does not have sufficient time to act. The control is then carried out after the transient phase and the user becomes aware of the regulation since it intervenes by modifying the torque supplied by the motor not during the transient phase but while the user expects to be in steady state. This control also leads to operating the engine in non-optimal combustion conditions during the transient phase and at the start of the stationary phase and therefore to an increase in fuel consumption. In summary, while in the automotive field, the controller acts during transient phases and arrives with the correct settings in steady state, in other, non-automotive applications, the operating mode used for the automotive field can lead to interventions of the controller sensitive to the user.

Summary

This disclosure improves the situation. Its particular aim is to provide a solution for controlling the torque of an engine, particularly during transient phases, which, on the one hand, makes it possible to optimize fuel consumption, and, on the other hand, limits or even limits removes sensitive effects for the end user. Preferably, this system will not require the use of new components in an engine in order to be implemented.

A method is proposed for controlling the engine torque of an internal combustion engine, said engine comprising:
- at least one system for regulating a flow of air entering the engine comprising a movable control member whose position makes it possible to act on the flow of air entering the engine, and
- an ignition system with a system for determining the ignition angle,
method in which, from a torque request from a user of said motor, an air flow setpoint value is determined,
- in which from the air flow setpoint value a position setpoint value of the mobile control member of the regulation system is determined
in which the air flow entering the engine as well as the position of the movable control member are measured, and
in which from measured and/or calculated quantities are determined, on the one hand, a quantity of fuel to be injected, and, on the other hand, an ignition angle.

According to the present disclosure, the quantity of fuel to be injected is calculated from the measured incoming air flow, and
the ignition angle is calculated from:
- the measured incoming air flow, possibly corrected, if the difference between the measured position of the mobile control member and the set value of the position of the mobile control member is greater than a predetermined position difference, And
- the set value of the incoming air flow if the difference between the measured position of the movable control member and the set value of the position of the movable control member is less than said predetermined position difference ( here one or the other alternative also includes the case where the difference is equal to the difference in predetermined position).

In this way, it is possible to avoid any unwanted withdrawal of ignition advance. As long as the position of the mobile control member is far from its set position, the ignition angle is calculated in a “classic” manner with the measured incoming air flow value. However, as soon as the position of this member approaches its set position, the calculation of the ignition angle is done with the set value of the position of the mobile control member and this makes it possible to avoid any withdrawal of advance, and therefore any degradation in consumption, as soon as the engine approaches its stationary speed.

A first alternative embodiment provides that the predetermined position difference is a fixed value.

Another variant provides that the predetermined position difference is a value depending on parameters, for example the position of the movable member itself and/or the engine speed and/or the atmospheric pressure and/or the temperature.

According to a preferred embodiment, corresponding to most current internal combustion engines, the system for regulating the air flow entering the engine comprises a throttle body in which the mobile control member is a flap, or butterfly, pivotally mounted makes it possible to modify the air passage section in said box, and in that the position of the butterfly is determined by its opening angle.

In this preferred embodiment, the difference in predetermined position of the movable control member corresponds to a difference in angular position of the throttle less than 1°, preferably less than 0.5° and even more preferably less than 0.1 °. It is indeed appropriate to provide a relatively small difference to maintain precision in the calculations carried out.

According to another aspect, an internal combustion engine is proposed comprising:
- at least one system for regulating a flow of air entering the engine comprising a movable control member whose position makes it possible to act on the flow of air entering the engine, and
- an ignition system with a system for determining the ignition angle,
characterized in that it further comprises an electronic control unit for the implementation of each of the steps of a method described above.

In this internal combustion engine, the system for regulating a flow of air entering said engine advantageously comprises:
- a butterfly housing in which the mobile control member is a flap, or butterfly, pivotally mounted making it possible to modify the air passage section in said housing, and
- an electric motor making it possible to vary the angular position of said butterfly.

According to another aspect, a computer program is proposed comprising instructions for the implementation of a method presented above when this program is executed by a processor, in particular an electronic control unit of an internal combustion engine.

According to another aspect, there is provided a non-transitory recording medium, readable by a computer, on which such a program is recorded.

Brief description of the figures

Other characteristics, details and advantages will appear on reading the detailed description below, and on analyzing the attached drawing, in which:

Fig. 1

And illustrate a torque control method known from the prior art.

Fig. 2

schematically illustrates a method according to the present disclosure.

Fig. 3

schematically illustrates an engine for implementing a method according to the present disclosure.

The present description is made in relation to an internal combustion engine 100 ( ), four-stroke type and spark ignition. In a manner known to those skilled in the art, an internal combustion engine comprises one or more cylinders, inside each of which there is a combustion chamber. Each combustion chamber is associated with at least one intake valve to manage gas flows entering the combustion chamber and at least one exhaust valve to manage gas flows leaving the combustion chamber. At least one air inlet is provided with a system for regulating the incoming air flow 110. This system generally corresponds to a device called a throttle body allowing the flow of air to be varied. fresh air entering the engine. In the illustrated embodiment, the position of the butterfly, that is to say of a flap pivotally mounted to modify the fresh air passage section of a supply duct, is controlled by an electric motor 120 It is important to know the air flow entering the engine to determine as precisely as possible the quantity of fuel to inject in order to optimize combustion to limit both fuel consumption and the emission of pollutants. To optimize the combustion of the injected fuel, it is necessary to determine an engine ignition angle, that is to say an engine position (in °CRK) at which a spark is produced in at least one cylinder. An ignition system 130 is therefore provided in the engine. The ignition system 130 comprises for example at least one spark plug per cylinder and means for producing a spark at one end of each plug upon receipt of a corresponding instruction.

An electronic management and control unit or controller 140 receives information from sensors and sends instructions to the various systems, for example to the system for regulating the incoming air flow 110 to act on the electric motor 120 and modify the angle of opening of the throttle or to the ignition system 130. Within this controller 140 there is in particular a system for determining the ignition angle 150 which makes it possible to determine at what moment, corresponding to a precise position of the engine, expressed by those skilled in the art in °CRK.

Such a structure is known to those skilled in the art and is not described in more detail here.

The motor 100 is for example a motor intended for non-automobile use, for example for a motorcycle, a tool such as a lawn mower, etc.

There illustrates a method known from the prior art for controlling the torque supplied by the motor. At input, a user makes a torque request TQ_REQ and from this request, a system called for example torque structure, provides a set value TPS_SP for the position of the throttle of the system for regulating the incoming air flow 130, a quantity QTF of fuel to be injected as well as an ignition angle value IGN_ANG.

The couple structure of the works as follows. From the user's TQ_REQ request, an incoming air flow setpoint MAF_SP is determined using an inverse torque model (REV_TQ_MOD) which may be an inverse mapping. This is an inverse model because, usually, a torque is determined from, among other things, a flow of fresh incoming air. To obtain this incoming air flow MAF_SP, it is necessary to adjust the throttle (or other system) to a setpoint position TPS_SP. The latter is also obtained by an inverse model REV_AP_MOD, or inverse air flow model. This may also be a reverse mapping.

The quantity of fuel to be injected QTF and the ignition angle IGN_ANG are determined by direct models. Input data are illustrated as non-limiting examples on the . We thus have for example the measured value TPS of the throttle position, the engine speed N, the atmospheric pressure MAP which can be measured or determined by software from pressure measurements in the engine, the incoming air flow measured MAF_MES (measured directly or calculated from sensor measurements, e.g. pressure, temperature, …), the TEMP temperature of the incoming air, etc.

The (direct) air flow model AP_MOD then makes it possible to calculate an incoming air flow MAF based on all these parameters. This value is then used to calculate the quantity of fuel to inject QTF, considering for example that the mixture is a stoichiometric mixture.

Taking into account the calculations carried out, it appears to those skilled in the art that there may be a difference between the MAF value and the MAF_SP setpoint value. From this MAF value, a direct torque model (TQ_MOD) makes it possible to determine a maximum torque that can be provided by the motor. If this maximum torque value is greater than the user's request (TQ_REQ), then it is possible to act on the ignition advance to adapt the torque supplied to the user's request. The 150 ignition angle determination system then limits the ignition advance if necessary. This then leads to a deterioration in engine efficiency corresponding to an increase in its consumption.

In steady state, such a structure works well and allows good performance for the engine. It also works for transient regimes in the automotive field because most often, motor vehicle engines have an intake manifold of one volume. In such engines, the controller 140 is most often capable of adjusting the position of the throttle during a transient phase and the user has no feeling of the action of the controller 140 while driving. As explained in the preamble, for engines intended for non-automotive applications, the transient phases are often briefer, the volume of the intake manifold is very reduced and the action of the controller 140 is still carried out during the stationary phase. following a transient phase and can then be felt by the user. In addition, a deterioration in efficiency, and therefore an increase in consumption, may occur.

The present disclosure proposes to modify the torque structure presented in Figures 1A and 1B to also adapt to non-automotive applications.

It is proposed here to decouple the determination of the quantity of fuel to be injected from the determination of the ignition angle. Furthermore, while the adjustment of the throttle position was decoupled from the determination of the quantity of fuel to be injected and the ignition angle, it is proposed to take into account the throttle position instruction TPS_SP to determine the ignition angle IGN_ANG.

The determination of the set value of the throttle position TPS_SP is done as explained above with reference to the : from a request from a user, TQ_REQ, using successively an inverse torque model REV_TQ_MOD and an inverse air flow model REV_AP_MOD, a flow setpoint value d is successively determined air entering the engine MAF_SP and then a set value for the throttle position TPS_SP.

The quantity of fuel to be injected QTF is also determined as explained with reference to the : from data measured by sensors or from data calculated (from data measured in particular) by the controller 140 or another electronic unit associated with the engine, a direct air flow model AP_MOD calculates an air flow entering the MAF engine and from it, the quantity of fuel to be injected is determined for example by the controller 140 or another electronic control and management unit (or unit known by the English acronym ECU).

The ignition angle IGN_ANG is determined from a variable MAF_TQS which can take two values, and more precisely either the value of the air flow MAF determined by the direct air flow model AP_MOD, or the value of MAF_SP setpoint determined by the inverse torque model REV_TQ_MOD.

It is proposed here to make the value of the variable MAF_TQS depend on the difference between the angular position of the throttle TPS and the set value TPS_SP. When the angular position of the throttle TPS is close to the set value TPS_SP, then it is proposed to give the variable MAF_TQS the set value of incoming air flow MAF_SP whereas if the angular position of the throttle is still far from its setpoint value, the variable MAF_TQS will then take the value of air flow entering the MAF motor determined by the direct air flow model AP_MOD.

The controller 140 then compares the TPS_SP and TPS values. It makes the difference between these two values and takes the absolute value:
|TPS – TPS_SP|.
If this value is less (or less than or equal to) a predetermined difference (epsilon or EPS) then it is considered that the angular position of the throttle is close to its set value.

On the , the answer to the question of whether:
|TPS – TPS_SP| <EPS
is yes corresponds to the value 1 while the negative answer corresponds to the value 0.

The EPS value can be a fixed value or be a value depending on parameters, for example the opening angle of the throttle (a small variation when the throttle is almost closed can lead to a significant variation in the air flow whereas when the throttle is wide open, a small variation is less sensitive to air flow), engine speed or atmospheric pressure. Whether fixed or dependent on variables, this EPS value preferably remains low: it is advantageously less than 1°, even more advantageously less than 0.5° and even less than 0.2°. If it is fixed, we can have for example EFS=0.1°. This angle corresponds to the angular position of the butterfly relative to its pivot axis in its housing.

With the process proposed here, compared to the process of the prior art presented above, everything happens in the same way, even in the transitional phase, until the butterfly arrives at, or is very close to, its position set point. At this time, to avoid any unwanted advance withdrawal and thus any degradation in terms of consumption, the advance withdrawal calculation is done with the air flow setpoint value. Thus, when the throttle approaches its final position (corresponding to the set position), any unwanted withdrawal of ignition advance is avoided. We thus obtain optimal consumption at the engine level.

In the case where, for example, the measured (calculated) air flow MAF would be greater than the set air flow (MAF_SP), the motor would then provide a torque greater than the requested torque (TQ_REQ) but combustion would take place in optimal conditions from a consumption point of view. This is of no consequence because a torque that is a few percent too high is not sensitive to the user who will automatically and naturally adapt his torque request to the reaction of his motorcycle, his tool or other. Thus, there is no feeling for the user and fuel consumption remains optimal. Conversely also, if MAF is lower than MAF_SP, the torque obtained will be less but there will be no unwanted withdrawal of the ignition advance. Here too, there is no feeling for the user who will naturally adapt his request and the torque structure ensures optimization of fuel consumption.

This technical solution can be applied in particular in engine control to improve fuel consumption and also improve driving pleasure for the user.

The proposed method, and the corresponding means for implementing this process, make it possible to better control the ignition angle in the engine by avoiding any unwanted advance withdrawal when the engine is in a stationary operating phase. It is then possible to optimize fuel consumption and limit the release of polluting materials.

The implementation of the present disclosure facilitates motor control and, under certain conditions, makes it possible to place less strain on the controller. Indeed, if the position of the throttle varies slightly while remaining close to the set value, the calculation of the ignition angle is done with the set value. So a small error in throttle position does not lead to a deterioration in fuel economy.

The process according to the present disclosure, illustrated in the , is also less sensitive to variations that may exist from one engine to another. The fact of using the setpoint value in steady state to determine the ignition angle makes the system less sensitive to dispersions which may exist from one engine to another.

It is estimated that a user is insensitive to torque level errors of up to approximately 5%. On the other hand, to limit polluting and CO2 emissions, a reduction in consumption of around 1% is not acceptable. The torque structure proposed here allows, by avoiding any withdrawal on the ignition advance, to maintain optimal consumption without impacting the user's pleasure.

The present disclosure is not limited to the proposed embodiments and the variants mentioned above, only by way of example, but it encompasses all the variants that those skilled in the art may consider in the context of protection. sought after.

Claims (9)

Method for controlling engine torque of an internal combustion engine, said engine comprising:
- a crankshaft, characterized by a top dead center,
- at least one system for regulating a flow of air entering the engine (110), said system comprising a mobile control member whose position makes it possible to act on the flow of air entering the engine, and
- an ignition system (130) with an ignition angle determination system (150), defining the angle of the crankshaft relative to the top dead center of said crankshaft at the time of ignition of the engine,
process in which:

1. from a torque request (TQ_REQ) from a user of said motor, an air flow setpoint value (MAF_SP) is determined,
2. from the air flow setpoint value (MAF_SP) a position setpoint value (TPS_SP) of the mobile control member of the regulation system (110) is determined,
3. the incoming air flow (MAF) into the engine as well as the position of the mobile control unit (TPS) are measured, and
4. from the torque demand (TQ_REQ) determined and the incoming air flow (MAF) measured, are determined, on the one hand, a quantity of fuel to be injected (QTF), and, on the other hand, an angle ignition (IGN_ANG),

the process being characterized in that:

• the quantity of fuel to be injected (QTF) is calculated from the measured incoming air flow (MAF), and
• the ignition angle (IGN_ANG) is calculated from:
  • of the measured incoming air flow (MAF), if the difference between the measured position of the movable controller (TPS) and the set value of the position of the movable controller (TPS_SP) is greater than one predetermined position difference (EPS), and
  • of the set value of the incoming air flow (MAF_SP) if the difference between the measured position of the movable controller (TPS) and the set value of the position of the movable controller (TPS_SP) is less than said predetermined position difference (EPS).

Method according to claim 1, characterized in that the predetermined position difference (EPS) is a fixed value. Method according to claim 1, characterized in that the predetermined position difference (EPS) is a value depending on parameters, for example the position of the movable member itself (TPS) and/or the engine speed (N) and/or atmospheric pressure and/or temperature. Method according to one of claims 1 to 3, characterized in that the system for regulating the incoming air flow (110) into the engine comprises a throttle body in which the mobile control member is a flap, or butterfly, pivotally mounted and makes it possible to modify the air passage section in said housing, and in that the position of the butterfly is determined by its opening angle. Method according to claim 4, characterized in that the difference in predetermined position (EPS) of the mobile control member corresponds to a difference in angular position of the throttle less than 1°, preferably less than 0.5° and preferably still less than 0.1°. Internal combustion engine (100) comprising:
- a crankshaft, characterized by a top dead center,
- at least one system for regulating a flow of air entering the engine (110) comprising a movable control member whose position makes it possible to act on the flow of air entering the engine, and
- an ignition system (130) with an ignition angle determination system (150), defining the angle of the crankshaft relative to the top dead center of said crankshaft at the time of ignition of the engine,
characterized in that it further comprises an electronic control unit (150) for implementing each of the steps of a method according to one of claims 1 to 5. Internal combustion engine (100) according to claim 6, characterized in that the system for regulating a flow of air entering (110) in said engine comprises:
- a butterfly housing in which the mobile control member is a flap, or butterfly, pivotally mounted making it possible to modify the air passage section in said housing, and
- an electric motor (120) making it possible to vary the angular position of said butterfly. Computer program comprising instructions for implementing a method according to one of claims 1 to 5 when this program is executed by a processor, in particular an electronic control unit of an internal combustion engine. Non-transitory recording medium readable by a computer on which is recorded a program for implementing a method according to one of claims 1 to 5 when this program is executed by a processor, in particular an electronic control unit d an internal combustion engine.