METHOD FOR DEACTIVATING A VEHICLE'S CROWDING MODE BASED ON CLUTCH TEMPERATURE

Abstract

The invention relates to a method for controlling a so-called "creeping" mode of a vehicle, suitable for moving said vehicle at low speed by supplying torque produced by a powertrain (10) without driver action on a brake or accelerator pedal, said powertrain (10) comprising a gearbox (16) having at least one clutch (K1, K2), said method comprising: - a step of measuring or estimating a temperature of the clutch (K1, K2), and - a step of deactivating the creeping mode if the temperature of the clutch (K1, K2) is above a deactivation threshold. Figure 1

Description

Title of the invention: METHOD FOR DEACTIVATING A CROWDING MODE OF A VEHICLE BASED ON CLUTCH TEMPERATURE

[0001] The present invention relates to a method for deactivating a creep mode of a vehicle based on the oil temperature of the gearbox. The invention has a particularly advantageous application with so-called automated motor vehicles.

[0002] The term "automated vehicle" herein refers both to a vehicle comprising a control system for components that automatically adapts the gear ratio of its powertrain to the wheels (such as, for example, a robotized gearbox), and to a vehicle that does not require this type of control system (such as, for example, a vehicle with an all-electric powertrain). Therefore, the invention relates in particular to vehicles with all-electric powertrains, vehicles with hybrid powertrains, and vehicles with powertrains that have an automated gear ratio mechanism (such as, for example, a robotized manual gearbox, a dual-clutch gearbox, an automatic gearbox, or a continuously variable transmission).

[0003] Furthermore, the term "creeping mode" (or "creep mode") refers to a powertrain operating mode that allows the vehicle to move autonomously at low speeds (typically 5 to 12 km / h on level ground) by providing variable torque as soon as the driver releases the brake and accelerator pedals while the vehicle is traveling at low speed. This autonomous driving mode (i.e., without driver intervention) is inherent to vehicles with automatic transmissions equipped with torque converters, allowing the driver to maneuver the vehicle more easily by temporarily applying only the brake pedal.

[0004] The creep mode has been implemented in many other automated vehicles to replicate the mechanical operation of the creep mode found in powertrains equipped with an automated gearbox incorporating a torque converter. The creep mode operates at low speeds, so that the gearbox clutch(es) are in a slipping state. The creep mode therefore contributes to heating the clutch(es) that transmit torque.

[0005] The invention aims to effectively remedy this drawback by proposing a method for controlling a so-called "creeping" mode of a vehicle, suitable for moving said vehicle at low speed by supplying torque produced by a powertrain without a driver needing to operate a brake or accelerator pedal, said powertrain comprising a gearbox including at least one clutch, said method comprising: - a step of measuring or estimating a clutch temperature, and - a step of deactivating the creep mode if the clutch temperature is above a deactivation threshold.

[0006] The invention thus makes it possible to avoid overheating and therefore deterioration of the clutch due to an uncontrolled activation of a creeping mode which can cause the clutch to overheat.

[0007] According to one embodiment of the invention, the vehicle having two clutches, the creep mode is deactivated only if the clutch that transmits torque has a temperature above the deactivation threshold.

[0008] According to one embodiment of the invention, the creeping mode is reactivated if the clutch temperature falls below a reactivation authorization threshold and if a reactivation action of the creeping mode occurs.

[0009] According to one embodiment of the invention, the action of reactivating the creeping mode is chosen from: releasing a brake pedal, pressing an accelerator pedal, or an action on a gear lever.

[0010] According to one embodiment of the invention, the deactivation threshold (Sdes) ​​and the reactivation authorization threshold are configured in the form of hysteresis, so that the creeping mode is deactivated when the clutch temperature becomes greater than the deactivation threshold and this deactivation is maintained until the clutch temperature becomes less than the reactivation authorization threshold which is less than the deactivation threshold.

[0011] According to one embodiment of the invention, the deactivation threshold is around 180°C and the activation authorization threshold is around 100°C.

[0012] According to one embodiment of the invention, the deactivation threshold and the reactivation authorization threshold depend on at least one parameter of the motor vehicle, such as speed or acceleration, and / or on at least one external parameter, such as a temperature external to the motor vehicle.

[0013] The invention also relates to a computer comprising a memory storing software instructions for the implementation of the process as previously defined.

[0014] The invention further relates to a motor vehicle comprising a control device as previously defined.

[0015] According to one embodiment of the invention, said vehicle comprises a dual-clutch gearbox.

[0016] The invention will be better understood upon reading the following description and examining the accompanying figures. These figures are given only to illustrate, but in no way limit, the invention.

[0017] [Fig-1] Fig. 1 is a schematic representation of a powertrain implementing a method according to the invention for deactivating a creeping walking mode;

[0018] [Fig.2] Fig.2 is a time diagram illustrating the implementation of the method according to the invention of deactivating a creeping mode as a function of a clutch temperature.

[0019] Fig. 1 shows a hybrid powertrain 10 of a motor vehicle comprising a thermal engine 11 and an electric transmission device 12 mounted on a wheel assembly 13, in particular a front wheel assembly.

[0020] The electric transmission device 12 includes a second torque generator, such as a rotating electric machine 15 and a dual-clutch gearbox 16 comprising two gear-change clutches K1, K2. The rotating electric machine 15 is arranged at the input of the dual-clutch gearbox 16.

[0021] The gearbox 16 comprises at least one input shaft 16.1, 16.1' and one output shaft 16.2. In this case, the gearbox 16 comprises a first input shaft 16.1 associated with a first set of gear ratios, for example, ratios 1-3-5, and connected to the clutch KL. A second input shaft 16.1' is associated with a second set of gear ratios, for example, ratios 2-4-6-7, and connected to the clutch K2. The output shaft 16.2 of the gearbox 16 is connected to the wheels via a differential and a downshaft (not shown).

[0022] The KO clutch is a clutch for connecting and disconnecting the internal combustion engine 11. The KO clutch is capable of selectively connecting the internal combustion engine 11 to the gearbox 16 when said KO clutch is in the closed state and of isolating the internal combustion engine 11 from the gearbox 16 when said KO clutch is in the open state. When torque from the internal combustion engine 11 is transmitted to the wheels, the KO clutch is closed, and the K1 and K2 clutches are alternately closed depending on the gear engaged. For this purpose, the KO clutch is positioned between the internal combustion engine 11 and the rotating electric machine 15. Isolating the internal combustion engine 11 from the gearbox 16, and therefore from the wheels, is required, in particular, when the vehicle is operating in a purely electric driving mode. The KO clutch is associated with a flywheel 17.

[0023] The rotating electric machine 15 is mounted between the clutch KO and the gear change clutches K1, K2 of the gearbox 16. The rotating electric machine 15 can be connected to the input of the gearbox 16 via a belt or chain reduction assembly 18.

[0024] The rotating electric machine 15 is capable of transforming electrical energy from a traction battery 19 into mechanical energy to provide traction to the vehicle by supplying torque to the vehicle's wheels. The rotating electric machine 15 is also capable of operating in a generator mode in which the rotating electric machine 15 transforms mechanical energy into electrical energy to recharge the traction battery 19, particularly during a regenerative braking phase.

[0025] An engine control unit 21 is capable of providing control of the powertrain 10, in particular torque control of the engine 11, the electric machine 15, as well as the opening, closing or slipping of the clutches KO, K1 and K2.

[0026] The engine control unit 21 or a dedicated control unit includes a memory storing software instructions for implementing the method according to the invention for deactivating a creep mode described below with reference to [Fig. 2]. The creep mode allows the vehicle to move at low speed by supplying torque produced by a powertrain (10) without a driver operating a brake or accelerator pedal.

[0027] The method includes a step of measuring or estimating the temperature of the clutch Kl, K2, and a step of deactivating the creep mode if the temperature of the clutch Kl, K2 is above a deactivation threshold Sdes. Advantageously, the creep mode is deactivated only if the clutch Kl, K2 that transmits torque has a temperature above the deactivation threshold Sdes. This allows the creep mode to be used with the second clutch, which is not overheating.

[0028] The creep mode is reactivated if the clutch temperature K1, K2 falls below a reactivation threshold Saut and if a creep mode reactivation action occurs. The creep mode reactivation action is selected from: releasing a brake pedal, pressing an accelerator pedal, or operating a gear lever.

[0029] Preferably, the deactivation threshold Sdes and the reactivation authorization threshold Saut are configured as hysteresis, so that the creep mode is deactivated when the clutch temperature Kl, K2 becomes greater than the deactivation threshold Sdes, and this deactivation is maintained until the temperature of the clutch Kl, K2 becomes below the reactivation authorization threshold Jump below the deactivation threshold Sdes.

[0030] As illustrated in [Fig. 2], as long as the temperature of the clutch TKi (i being 1 or 2 depending on the clutch) is below the deactivation threshold Sdes, the creep mode can be activated (the deactivation signal for creep mode Des_Ramp is 0). When the temperature of the clutch TKi exceeds the deactivation threshold Sdes at time Tl, the creep mode is deactivated (the deactivation signal Des_Ramp becomes 1). At time T2, the temperature of the TKi clutch falls below the Saut reactivation authorization threshold, so that the Des_Ramp deactivation signal returns to 0. From T2 onwards, the creep mode can be reactivated if a reactivation action occurs (releasing a brake pedal, pressing the accelerator pedal, or an action on a gear lever such as a shift to position D (for "Drive").

[0031] Following an example of implementation, the deactivation threshold Sdes is on the order of 180°C and the activation authorization threshold is on the order of 100°C. By "on the order of", we mean a possible variation of plus or minus 10% around the indicated value.

[0032] The deactivation threshold Sdes and the reactivation authorization threshold Saut may depend on at least one parameter of the motor vehicle, such as speed or acceleration, and / or on at least one external parameter, such as a temperature external to the motor vehicle.

Claims

Demands

1. A method for controlling a so-called "creeping" mode of a vehicle, suitable for moving said vehicle at low speed by supplying torque produced by a powertrain (10) without driver action on a brake or accelerator pedal, said powertrain (10) comprising a gearbox (16) having at least one clutch (Kl, K2), characterized in that said method comprises: - a step of measuring or estimating a temperature of the clutch (Kl, K2), and - a step of deactivating the creeping mode if the temperature of the clutch (Kl, K2) is above a deactivation threshold (Sdes), the creeping mode being reactivated if the temperature of the clutch (Kl, K2) falls below a reactivation authorization threshold (Saut) and if an action to reactivate the creeping mode occurs,The action to reactivate the creep mode is chosen from: releasing a brake pedal, pressing an accelerator pedal, or operating a gear lever.

2. Method according to claim 1, characterized in that the vehicle having two clutches (Kl, K2), the creep mode is deactivated only if the clutch (Kl, K2) which transmits a torque has a temperature above the deactivation threshold (Sdes).

3. A method according to claim 1 or 2, characterized in that the deactivation threshold (Sdes) ​​and the reactivation authorization threshold (Saut) are configured in the form of hysteresis, such that the creeping mode is deactivated when the clutch temperature (Kl, K2) becomes greater than the deactivation threshold (Sdes) ​​and this deactivation is maintained until the clutch temperature (Kl, K2) becomes less than the reactivation authorization threshold (Saut) which is less than the deactivation threshold (Sdes).

4. A method according to claim 3, characterized in that the deactivation threshold (Sdes) ​​is on the order of 180°C and the activation authorization threshold is on the order of 100°C.

5. A method according to any one of claims 1 to 4, characterized in that the deactivation threshold (Sdes) ​​and the authorization threshold of

6.

7.

8. reactivation (jump) depends on at least one parameter of the motor vehicle, such as speed or acceleration, and / or at least one external parameter, such as a temperature external to the motor vehicle. Calculator (21) comprising a memory storing software instructions for the implementation of the method defined according to any one of the preceding claims. Motor vehicle comprising a computer defined according to claim 6. Motor vehicle according to claim 7, characterized in that it comprises a dual-clutch gearbox (16) (Kl, K2).

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