SYSTEM AND METHOD FOR CORRECTING TORQUE FLUCTUATIONS IN A TRANSMISSION OF A HYBRID-DRIVE MOTOR VEHICLE

Description

[0001] The present invention relates to the field of hybrid propulsion motor vehicles comprising at least two different energy sources, and more precisely motor vehicles comprising on the one hand, a thermal engine and on the other hand, at least one electric machine.

[0002] More particularly, the present invention relates to systems and methods for attenuating or correcting oscillations generated in a hybrid transmission.

[0003] The advantage of hybrid transmissions is that they provide two sources of energy, thermal and electric, to the vehicle's drive train. The torque inputs from these two sources can be combined in a so-called "hybrid" mode or can be used separately, either in a so-called "pure thermal" mode where the electric machine does not provide torque to the drive train, or in a so-called "pure electric" mode, where the thermal engine does not provide torque to the drive train.

[0004] Hybrid transmissions allow the combustion engine to be powered while stationary or moving by using the electric motor as a starter. Hybrid transmissions also allow the vehicle's batteries to be charged by the electric motor acting as a generator.

[0005] However, torque discontinuities applied to the transmission input shaft, particularly when changing gear, starting the vehicle, braking, accelerating the vehicle sharply, etc., have a significant impact on the vehicle's acceleration. Indeed, the torque discontinuity generates oscillations in the rotational speed of the drive train, i.e., all the rotating elements that transmit the driving power to the vehicle's wheels. These oscillations in the rotational speed of the transmission elements result in oscillations in the vehicle's acceleration, and therefore in vehicle jerks. These jerks are felt in the vehicle's passenger compartment and are an inconvenience for the driver and vehicle occupants.

[0006] It is known to measure the rotational speeds of various components in the powertrain and adjust the torque setpoint of the electric motor based on the difference between the measured rotational speeds and a threshold. However, such systems are not efficient.

[0007] Reference may be made to document FR 2 910 198 which describes a method for controlling the correction of oscillations on the transmission shaft of a hybrid-powered motor vehicle. This method comprises a step of curative torque approval applied by an electric machine. However, it is not always possible to use the electric machine to provide a correction torque, in particular, for example, when the charge level of the vehicle's battery is not sufficient to provide the quantity of energy necessary for torque generation. Other methods for correcting oscillations are known from WO 2014 / 106709 A1, WO 2014 / 108620 A1, FR 3 000 993 and FR 2 875 545.

[0008] There is a need to improve vibration attenuation systems so that it can be applied in the majority of vehicle driving situations.

[0009] The objective of the invention is therefore to overcome these above drawbacks and to correct as best as possible the oscillations in the rotation speed generated in the transmission.

[0010] The invention aims to detect these vibrations in the drive train and to attenuate them as much as possible.

[0011] According to a first aspect, the invention relates to a system for correcting torque oscillations generated in a transmission of a hybrid propulsion motor vehicle as defined by claim 1.

[0012] Advantageously, the supervision module comprises a module for selecting the actuator according to the charge level of the battery connected to the electric machine, the temperature measured by temperature sensors, the state of the electric machine and the state of the drive train.

[0013] Advantageously, the supervision module comprises a module for activating the oscillation correction module associated with the selected actuator.

[0014] The oscillation detection module comprises, according to the invention, two low-pass filters arranged in series to filter the value of the rotation speed of the selected actuator, in order to isolate the frequencies due to the oscillation generated by a jolt and to invert the phase of the signal in order to be in phase opposition with the torque control setpoint coming from the control signal resulting from the driver of the vehicle pressing the accelerator pedal.

[0015] In one embodiment, the correction module comprises a module for calculating a correction setpoint as a function of the filtered value of the rotation speed of the selected actuator and a gain predetermined by the supervision module.

[0016] In one embodiment, the correction module comprises a means for calculating a corrected torque setpoint as a function of a torque value requested by the driver following pressing the accelerator pedal and said correction setpoint and a module for transmitting the corrected torque setpoint to the selected actuator.

[0017] According to a second aspect, the invention relates to a hybrid propulsion motor vehicle comprising a heat engine, at least one electric machine, a mechanical transmission connected to said heat engine, to said electric machine and to the wheels of the vehicle and a system for correcting the torque oscillations generated in said transmission as described previously.

[0018] In one embodiment, the motor vehicle comprises an electronic control unit capable of controlling the thermal engine, an inverter capable of controlling the electric machine and a general computer capable of controlling both the electronic control unit and the inverter. The supervision module is integrated directly into the general computer of the motor vehicle and the torque oscillation correction module is integrated directly respectively into the electronic control unit and into the inverter, in order to be as close as possible to the previously chosen actuator. There are therefore as many correction modules as there are actuators.

[0019] According to a third aspect, the invention relates to a method for correcting oscillations in a transmission of a hybrid-powered motor vehicle as defined by claim 9.

[0020] Other aims, characteristics and advantages of the invention will appear on reading the following description, given solely by way of non-limiting example, and made with reference to the appended drawings in which: there figure 1 schematically represents the architecture of a motor vehicle according to the invention; the figure 2 shows in detail the system for correcting oscillations in the rotation speed of the transmission of the figure 1 ; and the figure 3 represents a flowchart of a method for correcting oscillations in the rotation speed of the transmission according to an embodiment of the invention.

[0021] As illustrated on the figure 1 , a hybrid propulsion motor vehicle, referenced 10 as a whole, comprises a powertrain comprising a heat engine 12, an electric machine 14, a transmission 16 receiving torque from a first input shaft 18 connected to the output shaft 12a of the heat engine 12 via a first clutch 20, and torque from a second input shaft 22 connected to the output shaft 14a of the electric motor 14 via a second clutch 24, and a battery 26 connected to the electric motor 14.

[0022] The transmission 16 includes a gearbox, such as a planetary gear (not shown) that distributes torque to fixed ratio gears connected to the vehicle wheels 28a, 28b by a torque output shaft 30a, 30b. A differential mechanism 32 may be placed between the transmission 16 and the output shaft 30a, 30b.

[0023] The wheels can be the front or rear wheels of the hybrid vehicle.

[0024] Rotational speed sensors 34a, 34b, 34c are placed respectively on the first and second input shafts 18, 22 and on the output shaft of the transmission 16. The hybrid vehicle powertrain 10 further comprises a pedal position sensor 36 for determining the torque setpoint C cons requested by the driver.

[0025] The hybrid vehicle powertrain 10 comprises an electronic control unit (ECU) 40 which controls the thermal engine 12 and an inverter 42 which controls the electric motor 14. The hybrid vehicle powertrain 10 further comprises a general calculator 44, called in English terms “Hybrid Electric Vehicle Calculator” (HEVC) which controls both the electronic control unit (ECU) 40, the inverter 42 and the transmission 16 according to the data provided by the various sensors and the torque control setpoint requested by the driver of the vehicle.

[0026] As shown in the figure 2 , the motor vehicle comprises a torque oscillation correction system 50 comprising a supervision module 52 and a torque oscillation correction module 54.

[0027] The supervision module 52 is integrated directly into the general computer and includes a module 56 for selecting the actuator to be used which will be capable of ensuring torque correction. The actuator is chosen from the thermal engine or the electric motor depending on the battery level E bat , the temperature T measured by temperature sensors (not shown), the state of the electric machine E ME and the state of the kinematic chain E tr . By default, the supervision module 52 will choose the electric motor. Indeed, the electric motor allows greater precision and responsiveness compared to those of the thermal engine. However, in the event of an insufficient battery level, high heat, failure of the electric machine or when the state of the kinematic chain induces decoupling of the electric machine from the transmission, the supervision module will choose the thermal engine as the actuator.

[0028] The supervision module 52 further comprises a module 57 for determining the parameters of the low-pass filters and the gain making it possible to calculate a corrective torque setpoint value and a module 58 for activating the module 54 for correcting torque oscillations.

[0029] The torque oscillation correction module 54 is integrated directly into each of the actuators, i.e. into the inverter 42 and into the electronic control unit 40, in order to be as close as possible to the previously chosen actuator.

[0030] As illustrated, the torque oscillation correction module 54 comprises a module 60 for detecting an oscillation by observing the rotation speed ω of the actuator chosen by the supervision module.

[0031] The oscillation detection module 60 comprises two low-pass filters F1, F2 in series in order to isolate the frequencies due to the oscillation generated by a jolt and to invert the phase of the signal in order to be in phase opposition with the torque control setpoint C cons coming from the control signal resulting from the driver of the vehicle pressing the accelerator pedal.

[0032] The correction module 54 further comprises a module 62 for calculating the correction setpoint C corr by multiplying the filtered value of the filtered rotation speed ω of the chosen actuator by a gain K predetermined by the supervision module.

[0033] The corrective torque instruction C corr is subtracted in a subtracter 64 from the requested torque instruction C cons to deliver a corrected torque instruction C f to the actuator chosen by a module 66 for transmitting the corrected torque instruction C f .

[0034] Torque correction can therefore be applied regardless of the driving situation of the hybrid vehicle.

[0035] The correction signal is transmitted as close as possible to the selected actuator, i.e. to the inverter for the electric motor and to the electronic control unit for the combustion engine. This allows the time lag between oscillation measurement and torque generation to be reduced to a minimum, in order to achieve the most effective oscillation correction possible.

[0036] As illustrated on the figure 3, the method for correcting oscillations in the transmission comprises a first step 71 of selecting the actuator to be used which will be capable of ensuring the torque correction, a second step 72 of determining parameters to be taken into account to calculate a corrective torque setpoint, and a third step 73 of activating the module 54 for correcting the chosen actuator and transmitting the predetermined parameters. Said parameters determined in step 72 are determined, mainly, as a function of the rotation speed of the chosen actuator and the state of the kinematic chain, such as for example the selected gearbox ratio.

[0037] Once the correction module is activated directly as close as possible to the chosen actuator, the correction method comprises a step 74 of detecting the oscillation by observing the rotation speed of the chosen actuator, a step 75 of filtering the measured value of the rotation speed of the chosen actuator and a step 76 of calculating the corrective torque setpoint C corr to be applied to the torque setpoint C cons and a step 77 of transmitting the corrected torque setpoint C f to the previously chosen actuator.

[0038] The invention is applicable to any hybrid vehicle comprising at least one electric machine.

[0039] Thanks to the invention, oscillations in the transmission can be countered by injecting a torque in phase opposition directly at the level of the computers dedicated to each of the actuators present, that is to say to the thermal engine or to the electric motor.

[0040] In addition, coordinated control of transmission components helps to reduce the vehicle's energy consumption as much as possible and meet increasingly demanding pollution standards.

Claims

1. System (50) for correcting torque oscillations generated in a transmission of a hybrid-propulsion motor vehicle comprising a combustion engine (12), at least one electric machine (14) and a mechanical transmission (16) connected to said combustion engine, to said electric machine (14) and to the wheels (28a, 28b) of the vehicle, said system comprising: - a supervision module (52) able to select, out of the combustion engine and the electric machine (12, 14), the actuator capable of providing the torque correction, and - a torque oscillation correction module (54) able to deliver a corrected torque setpoint (Ccorr) as a function of the rotational speed (ω) observed at the output of the selected actuator, characterized in that the torque oscillation correction module (54) is integrated directly into each of the actuators (12, 14), and comprises an oscillation detection module (60) comprising two low-pass filters (F1, F2) in series in order to isolate frequencies due to an oscillation generated by a jerk and to invert the phase of the signal.

2. System (50) for correcting torque oscillations according to Claim 1, wherein the supervision module (52) comprises a module (56) for selecting the actuator based on the level of charge of the battery (Ebat) connected to the electric machine, on the temperature (T) measured by temperature sensors, on the state of the electric machine (EME) and on the state of the drivetrain (Etr).

3. System (50) for correcting torque oscillations according to Claim 1 or 2, wherein the supervision module (52) comprises a module (58) for activating the oscillation correction module (54) associated with the selected actuator.

4. System (50) for correcting torque oscillations according to any one of the preceding claims, wherein said two low-pass filters (F1, F2) arranged in series are configured to filter the value of the rotational speed (ω) of the selected actuator.

5. System (50) for correcting torque oscillations according to Claim 4, wherein the correction module (54) comprises a module (62) for computing a correction setpoint (Ccorr) as a function of the filtered value (ωfiltered) of the rotational speed (ω) of the selected actuator and of a gain (K) predetermined by the supervision module (52).

6. System (50) for correcting torque oscillations according to Claim 5, wherein the correction module (54) comprises a means (64) for computing a corrected torque setpoint (Cf), configured to subtract said correction setpoint (Ccorr) computed by said module (62) for computing a correction setpoint (Ccorr) from a torque value (Csetp) requested by the driver following pressing of the accelerator pedal, said correction module (54) furthermore comprising a module (66) for transmitting the corrected torque setpoint (Cf) to the selected actuator.

7. Hybrid-propulsion motor vehicle comprising a combustion engine (12), at least one electric machine (14), a mechanical transmission (16) connected to said combustion engine, to said electric machine (14) and to the wheels (28a, 28b) of the vehicle and a system (50) for correcting torque oscillations generated in said transmission according to any one of Claims 1 to 6.

8. Motor vehicle according to Claim 7, comprising an electronic control unit (40) able to control the combustion engine (12), an inverter (42) able to control the electric machine (14) and a general-purpose computer (44) able to control both the electronic control unit (40) and the inverter (42), the supervision module 52 being integrated directly into the general-purpose computer (44) of the motor vehicle and the torque oscillation correction module 54 being integrated directly into the electronic control unit (40) and into the inverter (42), respectively.

9. Method for correcting oscillations in a transmission of a hybrid-propulsion motor vehicle comprising a combustion engine (12), at least one electric machine (14) and a mechanical transmission (16) connected to said combustion engine, to said electric machine (14) and to the wheels (28a, 28b) of the vehicle, wherein said method comprises - determining, out of the combustion engine and the electric machine, the actuator capable of providing the torque correction, - detecting an oscillation in the transmission by observing the rotational speed at the output of the selected actuator, - filtering the observed speed using two low-pass filters (F1, F2) in series in order to isolate frequencies due to the oscillation generated by a jerk and to invert the phase of the signal, - computing a correction setpoint (Ccorr) as a function of the filtered value (ωfiltered) of the rotational speed (ω) of the selected actuator and of a gain (K) predetermined by the supervision module (52), - computing a corrected torque setpoint (Cf) as a function of a torque value (Csetp) requested by the driver following pressing of the accelerator pedal and said correction setpoint (Ccorr) - and transmitting the corrected torque setpoint (Cf) to the actuator selected out of the combustion engine and the electric machine.