FRONT-DRIVE HYBRID MOTOR VEHICLE INCLUDING A CONTROLLER THAT INHIBITS THE ROTATIONS OF THE ELECTRIC MOTOR IN CASE OF FAILURE, PROCESS AND PROGRAM BASED ON SUCH A VEHICLE

Abstract

The invention relates to a motor vehicle comprising a drive axle, including: - a gearbox (K1, K2); - an electric machine (ME); - a heat engine (MT) connected via a coupling means (K0); - at least one controller (S) for detecting malfunctions of the electric machine (ME), characterized in that when said controller (S) detects a malfunction of the electric machine (ME), it inhibits its operation and checks whether the rotational speed of the heat engine (MT) exceeds at least a threshold rotational speed, and if so, said controller (S) commands a corresponding upshift in the gearbox (K1, K2). The invention also relates to a method and a program based on such a vehicle. Figure 1

Description

Title of the invention: FRONT-DRIVE HYBRID MOTOR VEHICLE INCLUDING A CONTROLLER INHIBITING MACHINE ROTATIONS ELECTRICAL IN CASE OF FAILURE, PROCEDURE AND PROGRAM BASED ON SUCH A VEHICLE

[0001] The invention relates to the field of passenger safety in two-wheel drive hybrid vehicles, comprising an electric machine on a front powertrain.

[0002] On the applicant's two-wheel-drive hybrid vehicles, when the powertrain supervisor receives a fault signal from the front electric motor's computer indicating a malfunction for a specified period, the supervisor immobilizes the vehicle because the electric motor is directly connected to the gearbox's input shaft. Therefore, when the vehicle is in motion, the front electric motor's rotor is forced to rotate. Consequently, current is potentially generated in the front electric motor, which poses a risk of fire.

[0003] Thus, the said supervisor initiates the following recovery: - prohibition of starting the thermal machine before; - interruption of operation of the electric front-wheel drive machine; - request to open the clutch of the front gearbox clutch system, to disengage the internal combustion engine from the gearbox.

[0004] Furthermore, the supervisor requests the illumination of the stop light (“STOP” in English) on the dashboard, to warn the driver of a serious fault and the prohibition of using the vehicle, as long as the fault persists.

[0005] As a result, the vehicle is immobilized, which is disadvantageous for the driver and passengers, particularly from a safety standpoint. For example, in the event of an accident due to a sudden loss of torque from the drivetrain, this could cause serious injury to the passengers.

[0006] An objective of the present invention is to provide a recovery solution in case of malfunction of the electrical machine without having to immobilize the vehicle.

[0007] To achieve this objective, the invention proposes a motor vehicle comprising a traction axle, including: - a gearbox connected to the drive axle; - an electric machine connected to the gearbox; - a heat engine connected to the gearbox via a coupling means; - at least one controller controlling the gearbox, the electric machine and the internal combustion engine, and detecting malfunctions of the electric machine, characterized in that when said controller detects a malfunction of the electric machine, said controller inhibits the operation of the electric machine, and checks if the rotational speed of the internal combustion engine exceeds at least a threshold rotational speed, and if so, said controller commands a higher gear change corresponding to the gearbox.

[0008] Advantageously, the invention proposes a reconfiguration of the powertrain to ensure the safety of users and the vehicle without immobilizing the vehicle in the event that the computer of the front electric machine reports a fault prohibiting the use of the front electric machine.

[0009] Preferably, said controller includes a gear shift law relating to a gearbox control, characterized in that if said controller needs to perform a downshift on the basis of said law, it first checks whether the corresponding downshift implies a rotational speed of the internal combustion engine greater than said threshold rotational speed, and if so, said controller prohibits said downshift.

[0010] This helps to limit the risk of the electrical machine catching fire if it is necessary to downshift.

[0011] Preferably, when said controller detects a malfunction of the electrical machine, if the gearbox is in the highest gear, then said controller limits the rotation speed of the heat engine so that it does not exceed said threshold rotation speed.

[0012] This allows the rotation of the electric machine to be limited when the gearbox is in the highest gear.

[0013] Preferably, said controller comprises: - a gearbox control unit that controls the gearbox; - a machine computer controlling the electrical machine; - an engine control unit controlling the internal combustion engine; and - a supervisor controlling the gearbox computer, the machine computer, and the engine computer.

[0014] This allows it to be adapted to the usual controller configurations, and to have specific controllers for advanced control of the different devices of the vehicle.

[0015] Preferably, the motor vehicle comprises: - a hydraulic braking system; - a regenerative braking system, and - a stability control system connected to said controller, controlling said braking systems, and when said controller detects a malfunction of the electrical machine, said controller further inhibits the regenerative braking commands of the stability control system.

[0016] This makes it possible to limit the search for compromises between regenerative and hydraulic braking; and to limit braking defects.

[0017] Preferably, the motor vehicle further includes at least one vehicle stop and restart control system connected to the electrical machine, and when said controller detects a malfunction of the electrical machine, said controller further inhibits said stop and restart control system.

[0018] This helps to limit prolonged vehicle stops. In particular, a control system for stopping and restarting the internal combustion engine is provided and is not inhibited in the event of a fault in the electrical machine.

[0019] Preferably, the motor vehicle further includes an alerting means, and when said controller detects a malfunction of the electrical machine, said controller triggers the alerting means

[0020] This allows the driver to be informed of the fault and the reconfiguration of the powertrain.

[0021] Another object of the invention relates to a method for controlling a motor vehicle according to the invention, comprising the following steps: - a fault detection step in which a malfunction of the electrical machine is detected; - a machine inhibition step in which the operation of the electrical machine is inhibited; - a gear change step in which it is checked whether the rotational speed of the internal combustion engine exceeds at least a threshold rotational speed, and if so, a higher gear change corresponding to the gearbox is ordered.

[0022] Preferably, the control method further includes a downshifting step performing a lower gear change, and it includes a pre-checking step in which it is checked beforehand whether the corresponding lower gear implies a rotational speed of the heat engine greater than said threshold rotational speed, and if so, said lower gear change is prohibited.

[0023] Preferably, the control method further includes a limiting step in which, if the gearbox is in the highest gear, then the engine speed is limited of the rotation of the internal combustion engine so that it does not exceed a certain threshold rotation speed.

[0024] Preferably, the control method further includes an alert step in which the driver is alerted to the detection of a fault.

[0025] The invention further relates to a computer program comprising program code instructions for executing the steps of the control method according to the invention, when said program is running on a computer.

[0026] The invention will be further detailed by the description of non-limiting embodiments, and on the basis of the attached [Fig.1] which illustrates a powertrain architecture of a vehicle according to a preferred variant of the invention.

[0027] The architecture illustrated in [Fig.1] is composed as follows.

[0028] The vehicle includes a thermal engine MT. The thermal engine MT is connected to a coupling, here with pendulums J1, J2 allowing the filtering of the acyclicities of the thermal engine MT in order to reduce gearbox noises and internal humming of the vehicle.

[0029] The pendulum coupling Jl, J2 is itself connected to a clutch KO connected to the gearbox Kl, K2. When the clutch KO is open, it allows the internal combustion engine MT to be isolated, in particular when the control supervisor S determines that it is optimal to drive in pure electric mode (or when the driver requests driving in pure electric mode) without having to oppose the friction torque of the internal combustion engine MT.

[0030] The KO clutch can also allow the MT internal combustion engine to be started with a starter or an alternator-starter.

[0031] When the vehicle is running in hybrid mode or in pure thermal mode, the KO clutch is closed.

[0032] After this clutch KO is the electric machine ME which is connected to the input of the gearbox Kl, K2, here, by a chain (alternatively this electric machine ME can be connected to the input of the gearbox Kl, K2 by a cascade of gears or a belt).

[0033] This electric machine ME is powerful enough to drive the vehicle in pure electric traction, and it also allows the traction battery and / or the service battery to be recharged. This electric machine ME can behave as an electric motor during the vehicle's traction phases; and as an alternator during the vehicle's deceleration phases and / or during battery charging phases.

[0034] Next comes the Kl, K2 gearbox, which can be a dual-clutch gearbox, a pilot-operated gearbox, or an automatic gearbox. On The illustration shows a dual-clutch gearbox (with a K1 clutch and a K2 clutch).

[0035] In the case of a pilot-operated or automatic gearbox, it has only one clutch between the gearbox teeth and the electric machine ME. It is even possible to consider that there is no clutch between the electric machine ME and the gearbox teeth.

[0036] Next comes, as conventionally, the transverse transmissions which drive the front wheels R of the vehicle (we can speak of the front axle).

[0037] According to the invention, the control strategy is as follows:

[0038] The initial assumption is that the supervisor S receives from the machine's computer The electrical system upstream of ME receives information indicating that the electrical system upstream of ME is experiencing a technical problem, rendering it inoperative. Specifically, for the applicant, this manifests as the control unit of the electrical system ME sending a notification to the supervisory system (S) that the electrical system upstream of ME is unavailable for a period exceeding a threshold duration (Dl). This duration (DI) can be calibrated during the development of this function. The minimum order of magnitude for this duration is Dl, which is greater than 300 milliseconds.

[0039] Alternatively, the starting hypothesis may also be that the supervisor S receives only empty frames of information on the CAN network from the computer of the electrical machine before ME, the supervisor S detects a malfunction of the computer of the electrical machine before ME, or a break in the CAN network between the computer of the electrical machine before ME and the supervisor S.

[0040] When the above-mentioned starting hypothesis is positive (unavailability of the electric machine ME), the supervisor S triggers the new reconfiguration function.

[0041] First, the supervisor S inhibits the operation of the electric machine before ME. In particular, the supervisor S requests the electric machine control unit before ME to shut down (even if the supervisor S has no confirmation that the electric machine control unit ME is receiving information on the CAN network). In other words, the electric machine ME can no longer supply torque to the powertrain or draw torque to supply electrical current to the vehicle's traction battery.

[0042] However, as previously mentioned, the problem is that even if the electric motor before ME is switched off, if the vehicle continues to move forward, this means that the rotor of the electric motor ME is still rotating, because the rotor is directly connected without a decoupling system for the rotor of the electric motor before ME. Thus, to reduce the risk of the electric motor before ME catching fire, it is necessary to ensure that the rotational speed of the rotor of the electric machine before ME does not exceed a rotational speed noted Wl.

[0043] W1 is a limiting rotor speed; this limiting rotation speed is calibrated during the development of the control according to the invention. Currently, this maximum rotation speed when the ME electric machine is switched off is calibrated at 2800 rpm to ensure that the ME electric machine does not catch fire.

[0044] Furthermore, the supervisor S stores in its read-only memory the gear ratio between the rotational speed of the primary shaft of the gearbox K1, K2 and the rotational speed of the rotor of the electric machine ME. Thus, the supervisor S knows the maximum rotational speed of the primary shaft that must not be exceeded in order to avoid exceeding the rotational speed W1 of the rotor of the electric machine ME. Similarly, the supervisor knows the maximum rotational speed of the crankshaft of the internal combustion engine MT to avoid exceeding the rotational speed W1 of the rotor of the electric machine ME. We will refer here to the maximum crankshaft speed as W2.

[0045] Consequently, when the supervisor S is in this new reconfiguration mode, the supervisor S checks that the crankshaft rotation speed is always less than W2.

[0046] If the supervisor S detects that the crankshaft rotation speed exceeds or equals W2, then the supervisor S asks the gearbox computer Kl, K2 to shift to the next higher gear ratio (for example, it asks the gearbox Kl, K2 to shift from 3rd to 4th gear or from 4th to 5th gear, etc.).

[0047] When the shift law requires the gearbox Kl, K2 to return to a lower ratio, the supervisor S calculates the crankshaft rotation speed before the shift, to verify that during the downshift, the crankshaft rotation speed will not become greater than W2.

[0048] In particular, a simple downshift of one gearbox ratio Kl, K2 must not lead to exceeding the limit W2 of the crankshaft rotation speed, but it is the double downshifts of gearbox ratio Kl, K2 that the supervisor S prevents in this new reconfiguration mode.

[0049] Once the gearbox Kl, K2 is in the last higher gear (in our case, the 7th gear), the supervisor S restricts the crankshaft rotation speed to the W2 speed, and thus it restricts the vehicle speed, so that the rotor of the front electric machine ME does not exceed the W2 speed.

[0050] As seen previously, the front ME electric motor is switched off, so it can no longer draw torque from the front drivetrain to generate electrical current to recharge the high-voltage traction battery. Therefore, the supervisor S informs the stability control unit (known as "ESP") that regenerative braking is not possible. This means that when the driver presses on the vehicle's brake pedal, the stability controller will only command the vehicle's hydraulic braking system to accomplish vehicle braking according to the driver's brake pedal depress, therefore the stability controller will only perform braking in dissipative braking (without seeking to find the best compromise between the dissipative braking of the hydraulic system and regenerative braking, by controlling the electric machine before ME).

[0051] Furthermore, the supervisor S inhibits the stop and restart function (or “Stop and Start” in English), because the supervisor S will no longer have the possibility of using the electric machine before ME to restart the thermal engine MT.

[0052] Furthermore, the supervisor S can prevent the MT internal combustion engine from being switched off by the stop-start function. Indeed, the driver still has the option of switching off the MT internal combustion engine by turning off the vehicle's ignition, but the stop-start function is inhibited, so the MT internal combustion engine can no longer switch off automatically.

[0053] In addition, supervisor S requests the lighting of a so-called "SERVICE" light on the dashboard, to warn the driver that a fault has been detected and that the fault must be diagnosed by the maintenance service.

[0054] In addition, supervisor S requests the display on the dashboard of a message indicating that the maximum speed of the vehicle is limited following the detection of this fault, to inform the driver that he will not be able to exceed a certain vehicle speed.

[0055] Alternatively, a fault code can be stored in the memory of one of the vehicle's computers to help the maintenance service determine that the problem stems from a loss of communication between the gearbox computer Kl, K2 and the supervisor S.

[0056] Regarding the return to normal, if the electrical machine control unit (ECU) before the ME detects that the fault has disappeared, the ECU before the ME resumes sending the status frame of the electrical machine before the ME to the supervisor S, indicating that it is "available". This means that the behavior of the electrical machine ME has been restored. The supervisor S then restores normal vehicle operation, exiting this new powertrain reconfiguration mode.

[0057] Nevertheless, the fault code can be stored in one of the vehicle's computers, and remain stored in the memory of one of the vehicle's computers, so that during vehicle servicing, the maintenance service can notice the occasional failure, and carry out a check of the electrical machine before ME.

[0058] The invention further relates to a method and a control program implementing the elements discussed above. The program can be loaded into the memory of at least one controller or computer.

Claims

Demands

1. A motor vehicle comprising a drive axle, including: - a gearbox (Kl, K2) connected to the drive axle; - an electric machine (ME) connected to the gearbox (Kl, K2); - a heat engine (MT) connected to the gearbox (Kl, K2) via a coupling means (KO); - at least one controller (S) controlling the gearbox (Kl, K2), the electric machine (ME) and the heat engine (MT), and detecting malfunctions of the electric machine (ME), characterized in that when said controller (S) detects a malfunction of the electric machine (ME), said controller (S) inhibits the operation of the electric machine (ME), and checks whether the rotational speed of the heat engine (MT) exceeds at least a threshold rotational speed, and if so, said controller (S) commands a higher gear change corresponding to the gearbox (Kl, K2).

2. Motor vehicle according to claim 1, wherein said controller (S) includes a gear shift law relating to a gearbox control (K1, K2), characterized in that if said controller (S) needs to perform a downshift on the basis of said law, it first checks whether the corresponding downshift implies a rotational speed of the internal combustion engine (MT) greater than said threshold rotational speed, and if so, said controller (S) prohibits said downshift.

3. Motor vehicle according to any one of claims 1 to 2, characterized in that when said controller (S) detects a malfunction of the electrical machine (ME), if the gearbox (K1, K2) is in the highest higher gear, then said controller (S) limits the rotational speed of the internal combustion engine (MT) so that it does not exceed said threshold rotational speed.

4. A motor vehicle according to any one of claims 1 to 3, characterized in that said controller (S) comprises: - a gearbox control unit controlling the gearbox (K1, K2); - a machine control unit controlling the electric machine (ME); - an engine control unit controlling the internal combustion engine (MT); and - a supervisor controlling the gearbox computer, the machine computer, and the engine computer.

5. Motor vehicle according to any one of claims 1 to 3, comprising: - a hydraulic braking system; - a regenerative braking system, and - a stability control system connected to said controller (S), controlling said braking systems, characterized in that when said controller (S) detects a malfunction of the electric machine (EM), said controller (S) further inhibits the regenerative braking commands of the stability control system.

6. Motor vehicle according to any one of claims 1 to 4, further comprising at least one vehicle stop and restart control system connected to the electric machine (EM), characterized in that when said controller (S) detects a malfunction of the electric machine (EM), said controller (S) further inhibits said stop and restart control system.

7. A method for controlling a motor vehicle according to any one of claims 1 to 6, comprising the following steps: - a fault detection step in which a malfunction of the electrical machine (EM) is detected; - a machine inhibition step in which the operation of the electrical machine (EM) is inhibited; - a gear shift step in which it is checked whether the rotational speed of the internal combustion engine (IM) exceeds at least a threshold rotational speed, and if so, a higher gear shift corresponding to the gearbox (K1, K2) is commanded.

8. A control method according to claim 7, further comprising a downshifting step performing a lower gear change, characterized in that it comprises a preliminary control step in which it is checked beforehand whether the corresponding lower gear implies a rotational speed of the internal combustion engine (MT) greater than said threshold rotational speed, and if so, said lower gear change is prohibited.

9. A control method according to any one of claims 7 to 8, further comprising a limiting step in which, if the gearbox (K1, K2) is in the highest gear, then the gearbox is limited

10. the rotational speed of the internal combustion engine (MT) so that it does not exceed a certain threshold rotational speed. Computer program comprising program code instructions for performing the steps of the control process according to any one of claims 7 to 9, when said program is running on a computer.

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