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 CRAWLING MODE OF A VEHICLE BASED ON A CLUTCH TEMPERATURE

[0001] The present invention relates to a method for deactivating a creeping mode of a vehicle as a function of a gearbox oil temperature. The invention finds a particularly advantageous application with motor vehicles which are said to be automated.

[0002] Here, the term "automated vehicle" means both a vehicle comprising a system for controlling components making it possible to automatically adapt the gear ratio of its powertrain (or GMP) to the wheels (such as, for example, a robotized gearbox), and a vehicle not requiring this type of control system (such as, for example, an all-electric GMP vehicle). Consequently, the invention relates in particular to vehicles with an all-electric powertrain, vehicles with a hybrid powertrain, and vehicles with a powertrain with a gear ratio automation mechanism (such as, for example, a robotized manual gearbox, a dual-clutch gearbox, an automatic gearbox or a continuously variable gearbox).

[0003] Furthermore, herein, the term "creeping mode" (or "crawling") is understood to mean a mode of operation of the GMP which allows the vehicle to be moved, at low speed (typically 5 to 12 km / h on the flat) and autonomously, thanks to the supply of a variable torque as soon as the driver no longer acts on the brake pedal and accelerator pedal when the vehicle is traveling at low speed. This autonomous mode of movement (or rolling) (i.e. without driver intervention) is inherent to vehicles with automatic gearboxes with torque converters and in fact allows the driver to maneuver his vehicle more easily by temporarily operating only the brake pedal.

[0004] Creeping mode has been implemented in many other automated vehicles in order to reproduce the mechanical operation of creeping mode present on powertrains equipped with an automated gearbox comprising a torque converter. Creeping mode operates at low speeds, so that the clutch(es) of the gearbox are in a slipping state. Creeping mode therefore contributes to heating the clutch(es) which transmit(s) torque.

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

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

[0007] According to an implementation of the invention, the vehicle comprising two clutches, the creeping mode is deactivated only if the clutch which transmits a torque has a temperature higher than the deactivation threshold.

[0008] According to one implementation of the invention, the creep mode is reactivated if the clutch temperature becomes lower than a reactivation authorization threshold and if an action of reactivating the creep mode occurs.

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

[0010] According to an implementation 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 higher than the deactivation threshold and this deactivation is maintained until the clutch temperature becomes lower than the reactivation authorization threshold lower than the deactivation threshold.

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

[0012] According to one implementation 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 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 implementing the method 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 gearbox with double clutch.

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

[0017] [Fig-1] [Fig.l] 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 for deactivating a creeping mode depending on a clutch temperature.

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

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

[0021] The gearbox 16 comprises at least one primary shaft 16.1, 16.1' and one secondary shaft 16.2. In this case, the gearbox 16 comprises a first primary 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 primary 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 secondary shaft 16.2 of the gearbox 16 is connected to the wheels via a differential and a lowering axle (not shown).

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

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

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

[0025] An engine computer 21 is capable of controlling the powertrain 10, in particular controlling the torque section of the engine 11, the electric machine 15, as well as opening, closing or sliding the clutches KO, K1 and K2.

[0026] The engine computer 21 or a dedicated computer comprises a memory storing software instructions for implementing the method according to the invention for deactivating a creeping mode described below with reference to [Fig. 2]. The creeping mode makes it possible to move said vehicle at low speed by supplying a torque produced by a powertrain (10) without action by a driver on a brake pedal or an accelerator pedal.

[0027] The method comprises 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 greater than a deactivation threshold Sdes. Advantageously, the creeping mode is deactivated only if the clutch K1, K2 which transmits a torque has a temperature greater than the deactivation threshold Sdes. This makes it possible to have the creeping mode by using the second clutch which is not overheating.

[0028] The creeping mode is reactivated if the temperature of the clutch K1, K2 becomes lower than a reactivation authorization threshold Jump and if an action for reactivating the creeping mode occurs. The action for reactivating the creeping mode is chosen from: releasing a brake pedal, pressing an accelerator pedal, or acting on a gear lever.

[0029] Preferably, the deactivation threshold Sdes and the reactivation authorization threshold Saut are configured in the form of hysteresis, so that the creeping mode is deactivated when the temperature of the clutch Kl, K2 becomes higher than the deactivation threshold Sdes and this deactivation is maintained until the temperature of the clutch Kl, K2 becomes lower than the reactivation authorization threshold Saut lower than the deactivation threshold Sdes.

[0030] As illustrated in [Fig.2], as long as the clutch temperature TKi (i (valued at 1 or 2 depending on the clutch) is lower than the deactivation threshold Sdes, the creep mode can be activated (the creep deactivation signal Des_Ramp is worth 0). When the clutch temperature TKi exceeds the deactivation threshold Sdes at time T1, the creep mode is deactivated (the deactivation signal Des_Ramp goes to 1). At time T2, the clutch temperature TKi falls back below the reactivation authorization threshold Saut, so that the deactivation signal Des_Ramp goes back to 0. From T2, the creep mode can be reactivated if a reactivation action (releasing a brake pedal, pressing the accelerator pedal, or action on a gear lever such as a shift to position D (for "Drive" in English) occurs.

[0031] According to an example of implementation, the deactivation threshold Sdes is of the order of 180°C and the activation authorization threshold is of the order of 100°C. By "of 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 at least one external parameter, such as a temperature external to the motor vehicle.

Claims

Claims

1. Method for controlling a so-called "creeping" mode of a vehicle, capable of moving said vehicle at low speed by supplying a torque produced by a powertrain (10) without action by a driver on a brake pedal or an accelerator pedal, said powertrain (10) comprising a gearbox (16) comprising 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 greater than a deactivation threshold (Sdes).

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

3. Method according to claim 1 or 2, characterized in that the creep mode is reactivated if the temperature of the clutch (Kl, K2) becomes lower than a reactivation authorization threshold (Jump) and if an action of reactivating the creep mode occurs.

4. Method according to claim 3, characterized in that the action of reactivating the creeping mode is chosen from: releasing a brake pedal, pressing an accelerator pedal, or acting on a gear lever.

5. Method according to claim 3 or 4, characterized in that the deactivation threshold (Sdes) ​​and the reactivation authorization threshold (Jump) are configured in the form of hysteresis, so that the creeping mode is deactivated when the clutch temperature (Kl, K2) becomes higher than the deactivation threshold (Sdes) ​​and this deactivation is maintained until the clutch temperature (Kl, K2) becomes lower than the reactivation authorization threshold (Jump) lower than the deactivation threshold (Sdes).

6. Method according to claim 5, characterized in that the deactivation threshold (Sdes) ​​is of the order of 180°C and the activation authorization threshold is of the order of 100°C.

7. Method according to any one of claims 3 to 6, characterized in

8.

9.

10. that the deactivation threshold (Sdes) ​​and the reactivation authorization threshold (Saut) depend 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 implementing the method defined according to any one of the preceding claims. Motor vehicle comprising a computer defined according to claim 8. Motor vehicle according to claim 9, characterized in that it comprises a gearbox (16) with double clutch (Kl, K2).

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