Method for controlling a powertrain of a hybrid motor vehicle, control unit for said powertrain, and motor vehicle
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-04-26
- Publication Date
- 2026-03-04
AI Technical Summary
Hybrid motor vehicles experience reduced NVH performance due to frequent alternation between electric motors and internal combustion engines, leading to increased noise and vibrations, which negatively impacts occupant comfort and fuel efficiency.
A method for controlling the powertrain of hybrid vehicles that inhibits the restart of the internal combustion engine for a determined period after it has stopped, allowing the electric machine to provide traction alone, thereby reducing engine noise and vibrations, and optimizing fuel usage.
This approach enhances NVH performance, reduces fuel consumption, and decreases exhaust emissions, offering both financial and ecological benefits while adapting to real-time vehicle maneuvers.
Smart Images
Figure EP2024061687_31102024_PF_FP_ABST
Abstract
Description
DESCRIPTION TITLE OF THE INVENTION: METHOD FOR CONTROLLING A POWERTRAIN OF A HYBRID MOTOR VEHICLE, CONTROL UNIT FOR THIS GROUP AND MOTOR VEHICLE TECHNICAL FIELD OF THE INVENTION
[0001] The present invention relates generally to the automotive field, and more particularly to the hybrid automotive field.
[0002] It relates more particularly to a method for controlling a powertrain of a hybrid motor vehicle, a control unit configured to implement this method and a hybrid motor vehicle equipped with such a central unit. STATE OF THE ART
[0003] Hybrid motor vehicles have a combustion engine and at least one electric motor that enable them to provide traction and / or propulsion of the vehicle depending on the vehicle's operating conditions. For example, the vehicle's traction can sometimes be provided by the combustion engine alone, for example when the torque to be provided is high, sometimes by the electric motor, for example when the torque to be provided is low, and sometimes by both.
[0004] In order to reduce fuel consumption and improve the comfort of vehicle occupants, the combustion engine can be switched off when not in use.
[0005] One way to improve the comfort of the occupants of a hybrid vehicle is to bring the driving sensations closer to those felt in a fully electric vehicle, which amounts to reducing the noise and vibrations caused by the internal combustion engine. This is called improving NVH performance (Noise, Vibration, Harshness).
[0006] In a hybrid vehicle, the alternation between the electric motor and the internal combustion engine, and in particular the frequent starts of the combustion engine, are detrimental to NVH performance.
[0007] There is therefore a need to improve the NVH performance of hybrid vehicles. PRESENTATION OF THE INVENTION
[0008] In order to overcome the aforementioned drawback of the state of the art, the present invention proposes a method for controlling a powertrain of a hybrid motor vehicle comprising an internal combustion engine and an electric machine. The method comprises, after stopping the internal combustion engine, a step of inhibiting a restart of the internal combustion engine for a determined period following stopping the internal combustion engine.
[0009] Thus, thanks to the invention, the frequency of restarting the internal combustion engine is reduced. The noise and vibrations associated with starting the engine and its operation are therefore reduced; the NVH performance of the vehicle is thus improved. Furthermore, the reduced use of the internal combustion engine enabled by the invention results in fuel savings and a reduction in exhaust gas emissions. The invention is therefore advantageous from a financial and ecological point of view.
[0010] Furthermore, this process is simple and adapts in real time to the vehicle's maneuvers. It is also applicable to all hybrid architectures allowing purely electric traction.
[0011] Other advantageous and non-limiting characteristics of the method according to the invention, taken individually or in all technically possible combinations, are the following: - if the vehicle is instructed to start during the inhibition stage, the vehicle's traction is provided by the electric machine alone; - the stopping of the internal combustion engine is detected when the combustion engine passes from a previous state in which the internal combustion engine produces a non-zero torque to a current state in which the internal combustion engine no longer produces torque; - to determine the previous state of the internal combustion engine, it is intended to read a combustion engine control signal emitted before the current time; - the inhibition step is interrupted if the powertrain receives an instruction greater than a predetermined threshold; - the predetermined threshold is equal to the maximum setpoint that the electric machine can satisfy alone, when the internal combustion engine is stopped; - the predetermined threshold is equal to a first value if the vehicle is in forward mode and equal to a second value if the vehicle is in reverse mode; - the electric machine is coupled in rotation to the internal combustion engine, the detection of the stopping of the combustion engine comprising a detection of the passage of the rotation speed of the electric machine below a predetermined threshold; - the hybrid vehicle comprises another electric machine coupled in rotation to the internal combustion engine, the detection of the stopping of the internal combustion engine comprising a detection of the passage of the rotation speed of this other electric machine below a predetermined threshold.
[0012] The invention also provides a control unit for a hybrid motor vehicle configured to implement the method according to the invention.
[0013] The invention further provides a hybrid motor vehicle comprising a powertrain which comprises an internal combustion engine, an electric machine and which is equipped with a control unit according to the invention.
[0014] Of course, the various features, variants and embodiments of the invention may be combined with each other in various combinations to the extent that they are not incompatible or mutually exclusive. DETAILED DESCRIPTION OF THE INVENTION
[0015] The description which follows with reference to the appended drawings, given as non-limiting examples, will make it clear what the invention consists of and how it can be implemented.
[0016] On the attached drawings:
[0017] [Fig. 1] represents a hybrid motor vehicle according to the invention;
[0018] [Fig. 2] is a flowchart illustrating a mode of implementation of the control method according to the invention;
[0019] [Fig. 3] is a more detailed version of the flowchart in Figure 2.
[0020] The method according to the invention applies to a powertrain of a hybrid motor vehicle, such as that illustrated in Figure 1.
[0021] This hybrid motor vehicle 15 is typically a car (rear-wheel drive and / or front-wheel drive), but it could be a truck, a bus, a boat, or even an airplane.
[0022] It comprises an internal combustion engine 16 and at least one electric machine 17 which are both adapted to propel the vehicle 15 independently of each other.
[0023] This powertrain comprises for this purpose a transmission 18 which is coupled to drive wheels 19 of the vehicle 15 and which makes it possible to transmit the torques developed by the electric machine 17 and by the internal combustion engine 16 to these wheels 19.
[0024] This transmission 18 makes it possible to decouple the internal combustion engine 16 from the drive wheels 19 so that the vehicle 15 is propelled in “all-electric” mode. Preferably, it also makes it possible to decouple the electric machine 17 from the drive wheels 19 so that the vehicle 15 is propelled in “all-thermal” mode. It also makes it possible to simultaneously couple the electric machine 17 and the internal combustion engine 16 to the drive wheels 19.
[0025] The method according to the invention advantageously makes it possible to inhibit the starting of the internal combustion engine for a determined period At following the last stopping of the internal combustion engine. For example, during this determined period, the traction of the vehicle 15 is ensured by the electric machine 17.
[0026] The determined duration At is greater than or equal to 2 seconds.
[0027] The implementation of the method can in particular be carried out by a control unit 20 of the motor vehicle 15. For example, this control unit 20 comprises a microprocessor and a memory, and is configured to receive data from the various sensors and control interface of the motor vehicle 15. Among these data are the speed of each engine (crankshaft rotation speed), the value of the engine control signal chosen by the driver, the value of the torque supplied by the engine(s) in operation, the value of the torque transmitted to the wheels of the vehicle 15, etc.
[0028] The implementation method described below in connection with figures 2 and 3 makes it possible to inhibit the starting of the internal combustion engine 16 of the vehicle 15 for the determined duration At so that, during this determined duration At, only the electric machine 17 provides traction for the vehicle 15, unless a greater torque than that which the electric machine 17 is capable of providing is requested by the driver.
[0029] Figure 2 schematically illustrates an algorithm for implementing this embodiment, corresponding for example to the execution of a program code hosted on the memory of the control unit 20. The algorithm here comprises three functions.
[0030] A first function F1 is configured to detect a shutdown of the internal combustion engine 16 and to output a corresponding first output signal ENG_OFF_DLY_REQ_SET, or engine shutdown detection signal.
[0031] A second function F2 is configured to determine whether to interrupt the inhibition of the start of the internal combustion engine 16, either because the electric machine 17 is unable to provide the torque requested by the driver, or because the determined duration At has expired. The second function is configured to emit a corresponding second output signal ENG_OFF_DLY_REQ_RST, or request signal for interrupting the inhibition of the start of the engine.
[0032] A third function F3 is configured to synthesize the output signals provided by the first function F1 and the second function F2. The third function F3 therefore determines whether or not to inhibit the start of the internal combustion engine16. It provides a corresponding third output signal ENG_OFF_DLY_REQ, or start inhibition signal. These three functions are described and illustrated in more detail below.
[0033] The function F1 as illustrated in Figures 2 and 3 is configured to detect a shutdown of the internal combustion engine 16 when the internal combustion engine 16 transitions from a prior state in which the internal combustion engine 16 produces a non-zero torque to a current state in which the internal combustion engine 16 produces no torque. For this purpose, the first function F1 is here configured to receive and process two input signals from which it provides the first output signal ENG_OFF_DLY_REQ_SET.
[0034] A first input signal ENG_TQ_SP represents the value of a control signal of the internal combustion engine 16 (the one which made it possible to calculate the torque setpoint of the internal combustion engine 16 to be applied at the current time, at the crankshaft). Thus, when the stopping of the internal combustion engine 16 is detected, this signal will represent the engine torque value which was requested by the driver prior to stopping the internal combustion engine 16.
[0035] A second input signal HSG_SPD allows the speed of the internal combustion engine 16 to be known.
[0036] Here, for example, the situation can be considered in which the internal combustion engine 16 and the electric machine 17 are simultaneously coupled to the drive wheels 19. In this situation, the output shaft of the electric machine 17 of the motor vehicle 15 is rotationally connected to the crankshaft of the internal combustion engine 16.
[0037] The second input signal HSG_SP considered represents the speed of the electric machine 17, and therefore indirectly that of the internal combustion engine 16.
[0038] The first input signal ENG_TQ_SP and the second input signal HSG_SPD are for example delivered by functions implemented by the computing unit. The first output signal ENG_OFF_DLY_REQ_SET is here a logic signal whose value is TRUE if a shutdown of the internal combustion engine 16 is detected and FALSE if a shutdown of the internal combustion engine is not detected 16.
[0039] As shown in Figure 3, the first function F1 performs a first operation 4 for determining the current state of the engine or, in other words, for determining whether the internal combustion engine 16 is stopped. Thus, a first comparison 5 is performed between the value of the second input signal HSG_SPD and a first threshold value HSG_SPD_CST corresponding to a minimum rotation speed of the electrical machine 17 below which the internal combustion engine 16 is considered to be stopped (typically 125 revolutions per minute). If the value of the second input signal HSG_SPD is lower than the first threshold value HSG_SPD_CST, then an engine stop detection signal HSG_SPD_DET is emitted with the logic value TRUE. Otherwise, the logic value of the engine stop detection signal HSG_SPD_DET is FALSE.
[0040] The first function F1 further performs a second operation 1 making it possible to determine a state of the internal combustion engine 16 prior to the detection of the stop. Thus, a second comparison 2 is carried out between the value of the first input signal ENG_TQ_SP and a second threshold value ENG_TQ_SP_CST corresponding to a minimum rotation speed of the electric machine 17 above which it is considered that the first input signal ENG_TQ_SP corresponds to a substantial engine torque (typically ONm). If the value of the first signal ENG_TQ_SP is greater than the second threshold value ENG_TQ_SP_CST, then it is considered that, prior to stopping the engine, a torque was indeed requested by the driver. The first function F1 then delivers a torque detection signal ENG_TQ_DET, here a logic signal whose value is TRUE if a torque was requested prior to stopping the engine and as long as the value of the output signal ENG_OFF_DLY_REQ_SET is TRUE (this last aspect is represented by a flip-flop 3 in figure 1).
[0041] As illustrated by AND gate 6, if the values of the torque detection signal ENG_TQ_DET and the motor stop detection signal HSG_SPD_DET are TRUE, then the logic value of the first output signal ENG_OFF_DLY_REQ_SET becomes TRUE.
[0042] The logic value of the first output signal ENG_OFF_DLY_REQ_SET is in particular transmitted to a countdown function 11 which defines the determined duration At during which the internal combustion engine 16 is to be inhibited. The transition to the logic value TRUE of the first output signal ENG_OFF_DLY_REQ_SET causes the countdown to be triggered 12 and a counter signal ENG_OFF_DLY_TMR_STA corresponding to the countdown value, here a duration in seconds, to be output. A detection 13 of the end of the countdown, i.e. when the counter signal ENG_OFF_DLY_TMR_STA reaches the value 0, causes a logic end of counter signal ENG_OFF_DLY_TMR_END with the value TRUE to be output.
[0043] The second function F2 as illustrated in Figures 2 and 3 is configured to determine whether the electrical machine 17 is capable of providing the torque requested by the driver. For this purpose, the second function F2 is configured to receive and process three input signals to provide the second output signal ENG_OFF_DLY_REQ_RST.
[0044] A third input signal MAX_AVL_DL_TQ represents a flow of dimension X, where X is the number of electric drive train states present on the powertrain, i.e. the number of combinations of couplers and reducers which transmit the torque produced by the electric machine 17 to the drive wheels 19, and makes it possible to determine the maximum torque that the electric machine 17 is capable of providing for each drive train state. For example, here, the third input signal is a flow of dimension 3, a first dimension of which represents the value of the maximum torque of a first state of the drive train EV1_AVL_DL_TQ, which here corresponds to a first gear ratio of the gearbox of the motor vehicle 15, a second dimension of which represents the value of the maximum torque of a second state of the drive train EV2_AVL_DL_TQ, which here corresponds to a second gear ratio of the gearbox of the vehicle 15, and a third dimension of which corresponds to a third state of the drive train EV_RVR_AVL_DL_TQ, which here corresponds to the reverse gear of the motor vehicle 15.
[0045] A fourth input signal DRV_TQ_REQ is a reference signal representing the torque value requested by the driver. Its value depends, for example, on the rate at which the accelerator pedal is pressed.
[0046] A fifth input signal GEAR_LEVR_PSN is a logic signal representative of the position of the gear lever of the vehicle 15, which makes it possible to determine whether the reverse gear of the vehicle 15 is engaged.
[0047] The third, fourth and fifth input signals are, for example, delivered by functions implemented by the computing unit.
[0048] As shown in Figure 3, during a third operation 7, the second function F2 selects, from among the X dimensions of the third input signal, the electric drivetrain state making it possible to supply the maximum torque to the drive wheels 19, and provides the maximum torque value available in forward gear MAX_EV_AVL_DL_TQ and in reverse gear EV_RVR_AVL_DL_TQ.
[0049] In a fourth operation 8, the second function F2 determines the difference between the maximum available torque values MAX_EV_AVL_DL_TQ and EV_RVR_AVL_DL_TQ and the fourth input value DRV_TQ_REQ (torque requested by the driver, or setpoint).
[0050] A fifth operation 9 compares the difference obtained for forward motion with a third threshold value DRV_EV_TQ_DIFF_CST below which it is considered that the electric machine 17 is not able to provide the torque requested by the driver (for example 0 Nm). If the difference is less than the third threshold value DRV_EV_TQ_DIFF_CST, then a first logic signal of motor insufficiency DRV_EV_AVL_TQ_RST of value TRUE is emitted.
[0051] A sixth operation 10 compares the difference obtained for reverse gear to the threshold value DRV_EV_TQ_DIFF_CST and if the difference is less than the third threshold value and reverse gear is engaged (fifth signal input signal with the value TRUE), then a second logic signal of motor failure RVR_EV_AVL_Q_RST with the value TRUE is emitted.
[0052] A seventh operation 14 applies the logical OR operator to the first motor failure signal DRV_EV_AVL_TQ_RST, the second motor failure signal RVR_EV_AVL_Q_RST and the end of counter signal ENG_OFF_DLY_TMR_END. The result of this logical operation is the second output signal ENG_OFF_DLY_REQ_RST, which has the value TRUE if the electric motor is unable to provide the torque requested by the driver in forward or reverse gear, or if the countdown has ended.
[0053] The third function F3 as illustrated in Figures 2 and 3 is configured to inhibit or not the starting of the internal combustion engine 16 depending on the values of the first output signal ENG_OFF_DLY_REQ_SET and the second output signal ENG_OFF_DLY_REQ_RST. For this purpose, the third function F3 is configured to receive and process the first output signal ENG_OFF_DLY_REQ_SET and the second output signal ENG_OFF_DLY_REQ_RST in order to provide the third output signal ENG_OFF_DLY_REQ. If the first output signal ENG_OFF_DLY_REQ_SET has the value TRUE and the second output signal ENG_OFF_DLY_REQ_RST has the value FALSE, then the third function F3 emits the third output signal ENG_OFF_DLY_REQ whose logic value is TRUE. As long as the value of the third output signal ENG_OFF_DLY_REQ is TRUE, the start of the internal combustion engine 16 is inhibited.
[0054] The invention is not limited to the embodiments described herein in connection with Figures 2 and 3.
[0055] For example, an electric machine 17 has been described previously, which is rotationally connected to the internal combustion engine 16, by the rotational speed of which the rotational speed of the internal combustion engine 16 is determined (function F1) and the capacity of which to provide the torque requested by the driver is evaluated (function F2). The invention covers embodiments and embodiments in which the vehicle 15 comprises a second electric machine 17 which is not rotationally connected to the internal combustion engine 16. The determination of the rotational speed of the internal combustion engine 16 is then done using the first electric machine 17 and it is the capacity of the second electric machine 17 to provide the requested torque which is evaluated by function F2.
[0056] Furthermore, the function F2 compares the difference between the torque requested by the driver and the maximum torque that the electric machine 17 is capable of providing with the third threshold value. According to certain embodiments, this threshold value is zero or, in other words, the function F2 simply compares the torque requested and the maximum torque that the electric machine 17 is capable of providing.
[0057] Finally, an interruption of the inhibition step has been described in the case where the electric machine is not able to transmit sufficient torque to the drive wheels. The invention is not limited to this condition, and other conditions for interrupting the inhibition step are conceivable, for example in the case of an excessively low battery charge level, or if the electric machine and the thermal engine are located on separate axles of the vehicle and a four-wheel drive start is necessary, for example if the driving conditions are poor.
Claims
CLAIMS
1. Method for controlling a powertrain of a hybrid motor vehicle (15) comprising an internal combustion engine (16) and an electric machine (17), characterized in that it comprises, after stopping the internal combustion engine (16), a step of inhibiting a start of the internal combustion engine (16) for a determined duration (At) following stopping of the internal combustion engine (16).
2. Method according to claim 1, in which, in the event of a setpoint (DRV_TQ_REQ) to start the vehicle (15) during the inhibition step, traction of the vehicle (15) is ensured by the electric machine (17) alone.
3. The method of claim 1 or 2, wherein stopping of the internal combustion engine (16) is detected when the internal combustion engine (16) transitions from a prior state in which the internal combustion engine (16) produces non-zero torque to a current state in which the internal combustion engine (16) no longer produces torque.
4. Method according to claim 3, wherein, in order to determine the previous state of the internal combustion engine (16), provision is made to read a control signal (ENG_TQ_SP) of the internal combustion engine (16) emitted previously at the current time.
5. Method according to any one of claims 1 to 4, in which the inhibition step is interrupted if the powertrain receives an instruction greater than a predetermined threshold.
6. Method according to claim 5, in which the predetermined threshold is equal to the maximum setpoint that the electric machine (17) can satisfy alone, when the internal combustion engine (16) is stopped.
7. A method according to claim 5 or 6, wherein the predetermined threshold is equal to a first value if the vehicle (15) is in forward mode and equal to a second value if the vehicle (15) is in reverse mode.
8. A control method according to any one of Claims 1 to 6, wherein the electric machine is rotationally connected to the internal combustion engine (16) or the hybrid vehicle (15) comprises another electric machine rotationally connected to the internal combustion engine (16), the detection of the stopping of the internal combustion engine (16) comprising a detection (5) of the passage of the rotation speed (HSG_SPD) of the electric machine (17) which is rotationally connected to the internal combustion engine below a predetermined threshold (HSF_SPD_CST).
9. A control unit for a hybrid motor vehicle (15) configured to implement the method according to any one of claims 1 to 8.
10. Hybrid motor vehicle comprising a powertrain which comprises an internal combustion engine (16) and an electric machine (17), characterized in that it is equipped with a control unit (20) according to claim 9.