Method and system for controlling engine torque of internal combustion engine
By decoupling the butterfly valve position adjustment and determination of fuel injection and ignition angle in the engine, and using electronic control units to optimize the air flow and ignition angle, the engine torque control problem in transient stages in non-automatic applications is solved, and fuel consumption optimization and user experience are improved.
Patent Information
- Application Number
- CN202380063109.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2022-09-02
- Filing Date
- 2023-08-30
- Publication Date
- 2025-05-06
AI Technical Summary
In non-automatic applications, prior art has difficulty effectively controlling the torque of the engine during the transient phase, resulting in increased fuel consumption and control interventions that users can notice.
By decoupling the adjustment of the butterfly valve position and the determination of the fuel injection and ignition angle, the electronic control unit measures and adjusts the air flow rate and butterfly valve position according to the user's torque requirements, and calculates and optimizes the fuel injection volume and ignition angle.
Optimizing fuel consumption in transient phases is achieved, reducing control interventions that users can notice, and avoiding unnecessary reductions in ignition advances, ensuring that the engine provides optimal fuel consumption in a stable state.
Smart Images
Figure CN119948249A_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to a method and system for controlling drive torque of an internal combustion engine.
[0002] The technical field of the invention is therefore that of engine control for internal combustion engines. More particularly, the present disclosure is intended for non-automotive applications and more specifically, but not exclusively, relates to engines of reduced size such as used on motorcycles. Such engines may also be used for other applications of engines (lawn mowers or other motorized tools, etc.).
[0003] Still more particularly, the present disclosure relates to internal combustion engines in which a valve (referred to as a butterfly valve) controls the air flow into the engine, said butterfly valve being operated in a controlled manner (usually electrically). In such an engine, the operation of a pedal (referred to as an accelerator pedal or a handle or a lever or the like) by a user is converted into a torque demand (request), and the control and management system will then determine a set point value involving, for example, the opening angle of the butterfly valve, so that the engine provides a torque corresponding to the torque request of the user. Background Art
[0004] In a conventional manner, the electronic management and control unit or controller converts the torque request into a set point for the air flow entering the engine through an inverse torque model, and, in turn, the inverse air flow model converts the air flow set point into a set point for the opening position (or angle) of the butterfly valve. In addition, in a conventional manner, the controller uses a direct model for fuel injection and ignition: based on a certain number of data obtained using sensors, such as (non-exhaustive illustrative list) the opening angle of the butterfly valve, the engine speed, the intake pressure, the temperature, etc., an estimated air flow of the air actually entering the engine is calculated. This value of the air flow will allow, on the one hand, to determine the amount of gasoline to be supplied to the engine to carry out the combustion and, on the other hand, to determine the maximum torque that the engine can provide. Depending on the available maximum torque and the torque required (torque request), the ignition angle is determined. If the available torque is greater than the torque actually required, a reduction in the ignition advance will be implemented to obtain the set point value of the torque.
[0005] It will be noted that a great deal of calculations and cartography (in French, cartographie) are required. A small error in these calculations and / or cartography can result in a loss of about one percent in the efficiency of the engine. This corresponds to an increase in fuel consumption of the same order of magnitude relative to the optimized fuel consumption.
[0006] In the automotive field, the estimated air flow and the measured air flow are permanently compared and a correction is applied to the opening of the butterfly valve to make these values agree. In this way, the error between the estimated flow and the measured flow is compensated. Motor vehicles usually include an intake manifold of relatively large capacity. Due to this large-volume manifold, the controller can adjust the position of the butterfly valve quickly and even during transients, and the correction applied is not perceived by the driver and allows to have optimized operation as soon as steady state is reached.
[0007] For non-automotive applications, the transient phase is usually shorter and the controller does not have enough time to act. Control then takes place after the transient phase and the user is aware of the regulation, since the latter does not take place during the transient phase, but by modifying the torque provided by the engine when the user expects to be in steady state. This control also causes the engine to operate under non-optimal combustion conditions during the transient phase and at the beginning of the steady phase, and therefore leads to increased fuel consumption. In summary, whereas in the automotive field the controller acts during the transient phase and reaches steady state with appropriate settings, in other non-automotive applications, the operating mode used in the automotive field leads to interventions on the controller that are noticeable to the user. Summary of the invention
[0008] The present disclosure will improve this situation. In particular, the purpose of the present disclosure is to provide a solution for controlling the torque of an engine, in particular during transient phases, which allows on the one hand to optimize fuel consumption and on the other hand to limit or even eliminate the effects noticeable to the end user. Preferably, the system will not require the use of new components in the engine in order to be able to implement it.
[0009] Proposed is a method for controlling the engine torque of an internal combustion engine, the engine comprising:
[0010] at least one system for regulating the air flow entering the engine, said at least one system comprising a movable control member, the position of which allows acting on the air flow entering the engine, and
[0011] - an ignition system having a system for determining the ignition angle,
[0012] In the method, an air flow set point value is determined based on a torque demand of a user of the engine,
[0013] - in the method, based on the air flow setpoint value, a setpoint value for the position of the movable control member of the regulating system is determined,
[0014] - In the method, the air flow into the engine and the position of the movable control member are measured, and
[0015] In the method, on the one hand the fuel quantity to be injected and on the other hand the ignition angle are determined based on measured variables and / or calculated variables.
[0016] According to the present disclosure, the amount of fuel to be injected is calculated based on the measured intake air flow, and
[0017] The ignition angle is calculated as follows:
[0018] - if the difference between the measured position of the movable control member and the setpoint value of the position of the movable control member is greater than a predetermined position difference, calculating the ignition angle based on the measured intake air flow, which is possibly corrected, and
[0019] - If the difference between the measured position of the movable control member and the set point value of the position of the movable control member is less than the predetermined position difference, the ignition angle is calculated based on the set point value of the intake air flow (here, the one or other alternatives also include the case where the difference is equal to the predetermined position difference).
[0020] Thus, it is possible to avoid any unwanted reduction in ignition advance. As long as the position of the movable control member is far from its set point position, the ignition angle is calculated in a "conventional" manner using the measured intake air flow value. However, as soon as the position of this member approaches its set point position, the ignition angle is calculated using the set point value of the position of the movable control member, and this allows avoiding any reduction in advance and therefore any degradation in fuel consumption as soon as the engine approaches its steady state.
[0021] A first variant embodiment provides that the predetermined position difference is a fixed value.
[0022] Another variant provides that the predetermined position difference is a value that depends on a parameter, for example on the position of the movable component itself and / or the engine speed and / or the atmospheric pressure and / or the temperature.
[0023] According to a preferred embodiment corresponding to the majority of current internal combustion engines, the system for regulating the air flow into the engine comprises a throttle body, wherein the movable control member is a valve or a butterfly valve which is pivotally mounted and allows modification of the air passage cross section in the throttle body, and wherein the position of the butterfly valve is determined by its opening angle.
[0024] In the preferred embodiment, the predetermined position difference of the movable control member corresponds to an angular position difference of the butterfly valve of less than 1°, preferably less than 0.5° and still preferably less than 0.1°. In particular, a relatively small difference should be provided to maintain the accuracy of the calculations performed.
[0025] According to another aspect, an internal combustion engine is proposed, comprising:
[0026] at least one system for regulating the air flow entering the engine, said at least one system comprising a movable control member, the position of which allows acting on the air flow entering the engine, and
[0027] - an ignition system having a system for determining the ignition angle,
[0028] Therein, the internal combustion engine further comprises an electronic control unit for implementing each of the steps of the method described above.
[0029] In this internal combustion engine, the system for regulating the air flow entering the engine advantageously comprises:
[0030] - a throttle body, wherein the movable control member is a valve or a butterfly valve which is pivotably mounted and allows the air passage cross section in the throttle body to be modified, and
[0031] - an electric motor for varying the angular position of the butterfly valve.
[0032] According to another aspect, a computer program is proposed comprising instructions for implementing the method presented above when the program is executed by a processor, in particular an electronic control unit of an internal combustion engine.
[0033] According to another aspect, a computer-readable non-volatile storage medium having such a program stored thereon is proposed. BRIEF DESCRIPTION OF THE DRAWINGS
[0034] Further features, details and advantages will become apparent upon reading the following detailed description and upon studying the accompanying drawings, in which:
[0035] Figure 1A and Figure 1B A torque control method known from the prior art is illustrated.
[0036] Figure 2 A method according to the present disclosure is schematically illustrated.
[0037] Figure 3 An engine for implementing the method according to the present disclosure is schematically illustrated. DETAILED DESCRIPTION
[0038] This description is about an internal combustion engine 100 of the controlled ignition four-stroke type ( Figure 3 ). In a manner known to those skilled in the art, an internal combustion engine comprises one or more cylinders, inside each of which a combustion chamber can be found. Each combustion chamber has associated therewith at least one intake valve for managing the air flow into the combustion chamber and at least one exhaust valve for managing the air flow out of the combustion chamber. At least one air inlet is provided with a system 110 for regulating the incoming air flow. This system generally corresponds to a device known as a throttle body (or throttle valve), which is used to vary the fresh air flow into the engine. In the illustrated embodiment, the position of the butterfly valve (that is to say the position of the valve pivotably mounted to modify the fresh air passage cross section of the supply duct) is controlled by an electric motor 120. It is important to know the air flow into the engine in order to determine as accurately as possible the amount of fuel to be injected in order to optimize the combustion, and thus in order to limit both the fuel consumption and the pollutant emissions. In order to optimize the combustion of the injected fuel, the ignition engine angle, that is to say the engine position (in ° C RK) at which the spark is generated in at least one cylinder, should be determined. Therefore, an ignition system 130 is provided in the engine. Ignition system 130 includes, for example, at least one spark plug per cylinder, and means for generating a spark at one end of each spark plug upon receiving a corresponding command.
[0039] An electronic management and control unit or controller 140 receives information from the sensors and sends commands to various systems, for example to the system 110 for regulating the intake air flow in order to act on the electric motor 120 and modify the opening angle of the butterfly valve, or else to the ignition system 130. Within this controller 140, a system 150 for determining the ignition angle can be found in particular, which allows determining which moment corresponds to a precise position of the engine (expressed in °C RK by a person skilled in the art).
[0040] Such a structure is known to those skilled in the art and will not be described in detail here.
[0041] The engine 100 is, for example, intended for non-automotive use, such as for use in a motorcycle, a tool such as a lawn mower, or the like.
[0042] Figure 2 A method known from the prior art for controlling the torque provided by an engine is illustrated. As input, the user states a torque demand TQ_REQ and based on this demand, a system, for example referred to as the torque architecture, provides setpoint values TPS_SP for the position of a butterfly valve of a system 130 regulating the intake air flow, the amount of fuel to be injected QTF and the ignition angle value IGN_ANG.
[0043] Figure 2 The torque structure operates in the following manner. Based on the user's request TQ_REQ, a reverse torque model (REV_TQ_MOD) is used to determine the set point value MAF_SP of the incoming air flow, which can be a reverse mapping technique. What is involved is a reverse model, because conventionally the torque is determined especially based on the incoming fresh air flow. In order to obtain the incoming air flow MAF_SP, the butterfly valve (or another system) should be set to the set point position TPS_SP. The latter is also obtained by a reverse model REV_AP_MOD or a reverse air flow model. This can also be a reverse mapping technique.
[0044] The amount of fuel to be injected QTF and the ignition angle IGN_ANG are determined by the direct model. The input data are obtained by Figure 1B Thus, there are, for example, the following: a measurement of the position of the butterfly valve TPS, the engine speed N, the atmospheric pressure MAP (which can be measured or determined by software based on pressure measurements in the engine), a measured intake air flow MAF_MES (directly measured or calculated based on measurements from sensors, such as pressure sensors, temperature sensors, etc.), the temperature TEMP of the intake air, etc.
[0045] The (direct) air flow model AP_MOD then allows the calculation of the intake air flow MAF as a function of all these parameters. This value is then used to calculate the amount of fuel to be injected QTF, by taking into account, for example, that the mixture is a stoichiometric mixture.
[0046] Taking into account the calculations implemented, it would seem to a person skilled in the art that there may be a difference between the value MAF and the set point value MAF_SP. Based on this value MAF, the direct torque model (TQ_MOD) allows the determination of the maximum torque that can be provided by the engine. If this maximum torque value is greater than the user's request (TQ_REQ), it is possible to act on the ignition advance to adapt to the torque provided at the user's request. The system 150 for determining the ignition angle then limits the ignition advance (if necessary). This then results in a degradation of the efficiency of the engine, which therefore corresponds to an increase in its fuel consumption.
[0047] In steady state, this structure works well and allows to obtain good efficiency of the engine. In the automotive field, this structure also works for transients, because usually the engine of a motor vehicle comprises an intake manifold of large capacity. In such an engine, the controller 140 is usually able to adjust the position of the butterfly valve during the transient phase, and the user does not feel the action of the controller 140 at all when driving. As explained in the introduction, for engines intended for non-automotive applications, the transient phase is often shorter, the capacity of the intake manifold is greatly reduced, and the action of the controller 140 still occurs during the steady phase after the transient phase, and then the user can feel the action. In addition, there will be a degradation of efficiency and therefore an increase in fuel consumption.
[0048] This disclosure proposes modifications Figure 1A and Figure 1B The torque structure presented in the embodiment can also be adapted to non-automotive applications.
[0049] Here it is proposed to decouple the determination of the amount of fuel to be injected from the determination of the ignition angle. Furthermore, in view of the decoupling of the adjustment of the position of the butterfly valve from the determination of the amount of fuel to be injected and the ignition angle, it is proposed to take into account the position setpoint TPS_SP of the butterfly valve in order to determine the ignition angle IGN_ANG.
[0050] The set point value TPS_SP for the position of the butterfly valve is determined as mentioned above. Figure 1A It is implemented as explained: based on the user's request TQ_REQ, the setpoint value MAF_SP of the air flow into the engine and then the setpoint value TPS_SP of the position of the butterfly valve are continuously determined using the inverse torque model REV_TQ_MOD and the inverse air flow model REV_AP_MOD.
[0051] The amount of fuel to be injected QTF is also the same as reference Figure 1B The determination is made as explained: based on data measured by sensors, or else based on data calculated by a controller 140 or another electronic unit associated with the engine (in particular based on the measured data), the direct air flow model AP_MOD calculates the air flow MAF entering the engine, and the amount of fuel to be injected is determined based on this air flow MAF, for example by the controller 140 or another electronic control and management unit (or a unit referred to as ECU).
[0052] The ignition angle IGN_ANG is determined on the basis of a variable MAF_TQS which can take two values and, more precisely, either a value MAF of the air flow determined by a direct air flow model AP_MOD or a setpoint value MAF_SP determined by a reverse torque model REV_TQ_MOD.
[0053] It is proposed here that the variable value MAF_TQS depends on the difference between the angular position TPS of the butterfly valve and the setpoint value TPS_SP. When the angular position TPS of the butterfly valve approaches the setpoint value TPS_SP, then it is proposed to give the variable MAF_TQS the setpoint value MAF_SP for the air flow rate, and if the angular position of the butterfly valve is still far from its setpoint value, the variable MAF_TQS will then take the value MAF of the air flow rate into the engine determined by the direct air flow model AP_MOD.
[0054] Then, the controller 140 compares the values TPS_SP and TPS. The controller implements the difference between these two values and takes its absolute value:
[0055] |TPS – TPS_SP|.
[0056] If this value is less than (or less than or equal to) a predetermined difference (ε or EPS), the angular position of the butterfly valve is considered to be close to its setpoint value.
[0057] In Figure 2 the answer to the question of knowing whether |TPS – TPS_SP| < EPS
[0058] being yes corresponds to the value 1, while a negative answer corresponds to the value 0.
[0059] The value EPS can be a fixed value, or else it depends on the value of a parameter, for example on the opening angle of the butterfly valve (a small change leads to a large change in the air flow rate when the butterfly valve is almost closed, while a small change is less noticeable in the air flow rate when the butterfly valve is wide open), the engine speed, or else the atmospheric pressure. Whether it is fixed or depends on a variable, the value EPS is preferably kept small: it is advantageously less than 1°, still more advantageously less than 0.5° and even less than 0.2°. If it is fixed, it is possible for example to make EPS = 0.1°. This angle corresponds to the angular position of the butterfly valve relative to its pivot axis in its throttle body.
[0060] For the method proposed here, everything continues in the same way as for the prior art method presented above, even during the transient phase, until the butterfly valve reaches or is very close to its setpoint position. At this time, in order to avoid any unwanted reduction in advance and thus avoid any degradation in fuel consumption, the setpoint value of the air flow rate is used to complete the advance reduction calculation. Thus, when the butterfly valve approaches its final position (corresponding to the setpoint position), any unwanted reduction in ignition advance is avoided. Thus, the best fuel consumption in the engine is obtained.
[0061] If, for example, the measured (calculated) air flow MAF would be greater than the set point air flow (MAF_SP), the engine would then provide a torque greater than the torque required (TQ_REQ), but the combustion would take place under optimal conditions from the point of view of fuel consumption. This has no consequences, since the user will not notice the excessively high torque (a few percentage points higher), he will automatically and naturally adapt to the torque request depending on the reaction of his motorcycle, his tools, etc. The user therefore does not feel any problem and the fuel consumption remains optimal. Likewise, on the contrary, if the MAF is less than MAF_SP, the torque obtained will be smaller, but there will be no unwanted reduction in the ignition advance. Here again, the user does not feel any problem, he will naturally adapt to his request and the torque structure ensures the optimization of fuel consumption.
[0062] Industrial Applications
[0063] The technical solution can be applied in particular to engine control in order to improve fuel consumption and also to improve driving comfort for the user.
[0064] The proposed method and the corresponding means for implementing the method allow better control of the ignition angle in the engine while avoiding any unwanted reduction of the advance when the engine is in a stable operating phase. It is then possible to optimize fuel consumption and limit the emission of pollutants.
[0065] Embodiments of the present disclosure facilitate engine control and allow for reduced stress on the controller under certain conditions. Specifically, if the position of the butterfly valve changes slightly while remaining close to the set point value, the set point value is used to calculate the ignition angle. Therefore, small position errors of the butterfly valve do not result in a degradation of fuel economy.
[0066] Figure 2 The method according to the present disclosure illustrated in is also less sensitive to variations that may exist from engine to engine. The fact that the setpoint value is used to determine the ignition angle in steady state makes the system less sensitive to differences (dispersion in French) that may exist from engine to engine.
[0067] It is believed that users are insensitive to torque level errors of up to approximately 5%. On the other hand, a fuel consumption degradation of approximately 1% is unacceptable in order to limit polluting emissions and CO2. The torque structure proposed here allows maintaining optimal fuel consumption while avoiding any reduction in ignition advance, without affecting user comfort.
[0068] The present disclosure is not limited to the exemplary embodiments presented and to the stated variants described above purely by way of example, but encompasses all variants that a person skilled in the art might envisage within the scope of the protection sought.
Claims
1. A method for controlling engine torque of an internal combustion engine, the engine comprising: - a crankshaft characterized by its top dead center, at least one system (110) for regulating the air flow entering the engine, said system comprising a movable control member, the position of which allows acting on the air flow entering the engine, and - an ignition system (130) having a system (150) for determining the ignition angle, the ignition angle defining the angle of the crankshaft relative to the top dead center of the crankshaft when the engine is ignited, In the method: a. determining an air flow set point value (MAF_SP) based on the torque demand (TQ_REQ) of the engine user, b. determining a position set point value (TPS_SP) of a movable control member of the regulating system (110) based on the air flow set point value (MAF_SP), c. measuring the air flow into the engine (MAF) and the position of the movable control member (TPS), and d. Based on the determined torque demand (TQ_REQ) and the measured intake air flow (MAF), determining on the one hand the amount of fuel to be injected (QTF) and on the other hand the ignition angle (IGN_ANG), The method is characterized in that: the amount of fuel to be injected (QTF) is calculated based on the measured intake air flow (MAF), and The ignition angle (IGN_ANG) is calculated as follows: o calculating the ignition angle based on the measured intake air flow (MAF) if the difference between the measured position of the movable control member (TPS) and the set point value of the position of the movable control member (TPS_SP) is greater than a predetermined position difference (EPS), and o If the difference between the measured position of the movable control member (TPS) and the set point value of the position of the movable control member (TPS_SP) is less than the predetermined position difference (EPS), the ignition angle is calculated based on the set point value of the intake air flow (MAF_SP).
2. The method according to claim 1, wherein: The predetermined position difference (EPS) is a fixed value.
3. The method according to claim 1, wherein: The predetermined position difference (EPS) is a value that depends on parameters, for example on the position of the movable component itself (TPS) and / or the engine speed (N) and / or the atmospheric pressure and / or the temperature.
4. The method according to any one of claims 1 to 3, wherein: A system (110) for regulating the air flow into the engine comprises a throttle body, wherein the movable control member is a valve or a butterfly valve which is pivotally mounted and allows the air passage section in the throttle body to be modified, and wherein the position of the butterfly valve is determined by its opening angle.
5. The method according to claim 4, wherein: The predetermined position difference (EPS) of the movable control member corresponds to an angular position difference of the butterfly valve of less than 1°, preferably less than 0.5° and still preferably less than 0.1°.
6. An internal combustion engine (100), comprising: - a crankshaft characterized by its top dead center, at least one system (110) for regulating the air flow entering the engine, said at least one system comprising a movable control member, the position of which allows acting on the air flow entering the engine, and - an ignition system (130) having a system (150) for determining the ignition angle, the ignition angle defining the angle of the crankshaft relative to the top dead center of the crankshaft when the engine is ignited, Therein, the internal combustion engine further comprises an electronic control unit (150) for implementing each of the steps of the method according to any one of claims 1 to 5.
7. The internal combustion engine (100) according to claim 6, wherein: A system (110) for regulating air flow into the engine comprises: - a throttle body, wherein the movable control member is a valve or a butterfly valve which is pivotably mounted and allows the air passage cross section in the throttle body to be modified, and - an electric motor (120) for varying the angular position of the butterfly valve.
8. A computer program comprising instructions for implementing the method according to any one of claims 1 to 5 when the program is executed by a processor, in particular an electronic control unit of an internal combustion engine.
9. A computer-readable non-volatile storage medium having a program stored thereon for implementing the method according to any one of claims 1 to 5 when the program is executed by a processor, in particular an electronic control unit of an internal combustion engine.