CONTROL OF TORQUE TRANSMITTED BY THE DRIVE WHEELS OF A VEHICLE IN THE EVENT OF A REQUEST TO DEACTIVATE THE ANTI-SKID FUNCTION

Abstract

A control method is implemented in a land vehicle comprising, on the one hand, an electric drive unit capable of delivering a motor torque to the drive wheels based on torque information representing the driver's intent, and, on the other hand, a slip control function capable of acting on the electric drive unit. This method includes a step (10-40) in which, if the driver requests deactivation of the slip control function, the slip control function is operated in a specific mode in which it links a speed setpoint of the electric drive unit to the torque information. Figure 3

Description

Title of the invention: CONTROL OF TORQUE TRANSMITTED BY THE DRIVE WHEELS OF A VEHICLE IN CASE OF A REQUEST TO DEACTIVATE THE ANTI-PASTE AGE FUNCTION Technical field of the invention

[0001] The invention relates to land vehicles comprising an electric drive machine and a slip control function, and more specifically the control of the torque transmitted by the drive wheels of such vehicles in the event of a request to deactivate the slip control function. State of the art

[0002] Certain land vehicles, possibly of the motor vehicle type, include a powertrain (or PWM), comprising at least one electric motor, and a slip control (or anti-slip) function.

[0003] For example, the slip control function can be of the ASR (“Acceleration Slip Regulation”) or TCS (“Traction Control System”) type.

[0004] As those skilled in the art know, when the driver's (land) intention regarding engine torque is greater than the torque that can be transmitted by the drive wheels (without loss of grip) and this intention is respected, then the drive wheels will slip.

[0005] When the traction control function is effectively deactivated and the vehicle's powertrain is purely internal combustion, the torque transmitted to the drive wheels can be modulated by the driver because the engine torque supplied by the internal combustion engine (and dependent on the driver's input) is progressive. However, this is not the case when the powertrain includes at least one electric motor, as the engine torque is immediately transmissible. Consequently, in low-traction conditions when the traction control function is deactivated, the vehicle becomes unstable in yaw and its traction is zero because modulating the engine torque(s) is not possible, and therefore the drive wheels will slip significantly.

[0006] The invention therefore aims in particular to improve the situation. Presentation of the invention

[0007] In particular, it proposes for this purpose a control method intended to be implemented in a land vehicle comprising, on the one hand, an electric drive machine capable of delivering to drive wheels a motor torque that is a function of a torque information representing a driver's intention, and, on the other hand, a slip control function capable of acting on the electric drive machine.

[0008] This control method is characterized by the fact that it includes a step in which, if the driver requests deactivation of the slip control function, the slip control function is operated in a specific mode in which it controls a speed setpoint of the electric motor machine on the torque information.

[0009] Thanks to the invention, the slip control function simulates the behavior of a thermal engine, thus allowing the driver to control the torque transmitted to the drive wheels, and consequently avoids strong slippage of the drive wheels in the event of deactivation of the slip control function.

[0010] The control method according to the invention may include other features which may be taken separately or in combination, and in particular:

[0011] - in its stage, in the specific mode the skating control function can determine a difference between the torque information and a torque transmissible by the drive wheels without loss of traction, then if this difference is positive the slip control function can determine at least one speed setpoint of the electric drive machine which is a function of this determined difference;

[0012] - in the presence of the first option, in its step, in the specific mode the slip control function can determine a maximum speed setpoint for the electric drive machine which is a function of the determined difference;

[0013] - also in the presence of the first option, in its step, in the mode Specifically, the slip control function can determine the speed setpoint of the electric drive machine proportionally to the determined difference;

[0014] - also in the presence of the first option, in its step, in the mode Specifically, the slip control function can determine the torque that can be transmitted by the drive wheels without loss of grip, based on a torque transmitted by the drive wheels and information that is representative of a loss of grip of at least one drive wheel;

[0015] - in its step, the request to deactivate the skating control function may result from a dedicated action by the driver and / or a selection by the driver of a specific vehicle drive mode.

[0016] The invention also proposes a computer program product comprising a set of instructions which, when executed by processing means, is suitable for implementing a control method of the type described above, in a land vehicle comprising, on the one hand, an electric drive machine capable of delivering to drive wheels a motor torque that is a function of torque information representing the intent of a driver, and, on the other hand, a function of slip control specific to acting on the electric drive machine, to control a torque transmitted by the drive wheels in case of a request to deactivate the slip control function by the driver.

[0017] The invention also proposes a control device intended to equip a land vehicle comprising, on the one hand, an electric drive machine capable of delivering for drive wheels a motor torque as a function of torque information representing a driver's intention, and, on the other hand, a slip control function capable of acting on the electric drive machine.

[0018] This control device is characterized by the fact that it includes at least one processor and at least one memory arranged to perform the operations consisting, in the event of a request to deactivate the slip control function by the driver, of triggering a control of a speed setpoint of the electric motor machine on the torque information by the slip control function.

[0019] The invention also proposes a land vehicle, possibly of the automobile type, comprising, firstly, an electric drive machine capable of delivering for drive wheels a motor torque as a function of torque information representative of a driver's will, secondly, a slip control function capable of acting on the electric drive machine, and, thirdly, a control device of the type of that presented above.

[0020] For example, in this vehicle the control device may be part of a computer controlling the slip control function. Brief description of the figures

[0021] Other features and advantages of the invention will become apparent from an examination of the detailed description below, and the accompanying drawings, in which:

[0022] [Fig. 1] schematically and functionally illustrates an example of an embodiment of a vehicle comprising a powertrain with an electric drive machine and associated with a supervisory computer, a computer controlling a slip control function, and a control device according to the invention,

[0023] [Fig.2] schematically and functionally illustrates an example of an embodiment of a computer controlling the slip control function and comprising a control device according to the invention, and

[0024] [Fig.3] schematically illustrates an example of an algorithm implementing a control method according to the invention. Detailed description of the invention

[0025] The invention aims in particular to provide a control method, and an associated DC control device, intended to allow control of the torque transmitted by the drive wheels of a land vehicle V, ensuring a function of traction control (or anti-slip), in case the driver requests to deactivate this traction control function.

[0026] In what follows, the land vehicle V is considered, by way of non-limiting example, to be of the automobile type. This is, for example, a car, as illustrated in [Fig. 1]. However, the invention is not limited to this type of land vehicle. It relates in fact to any type of land vehicle comprising a powertrain with a drivetrain including at least one electric drive unit and providing a slip control function. Thus, it relates to all wheeled land vehicles (commercial vehicles, motorhomes, minibuses, coaches, trucks, motorcycles, road maintenance vehicles, construction equipment, agricultural machinery, and recreational vehicles (go-karts), for example).

[0027] A (land) vehicle V comprising an electric GMP transmission chain (and therefore an electric motive machine MME), a CS supervisory computer, an RB on-board network, a BS auxiliary battery, a BR rechargeable battery, a CV converter, a CFI computer controlling a slip control function, and a DC control device according to the invention is schematically represented in [Fig.1].

[0028] The RB on-board network is an electrical power supply network to which electrical (or electronic) equipment (or components) that consume electrical energy are coupled.

[0029] The auxiliary battery BS is responsible for supplying electrical power to the vehicle's electrical system RB, supplementing that supplied by the CV converter powered by the rechargeable battery BR, and sometimes replacing this CV converter. For example, this auxiliary battery BS may be configured as a very low voltage type battery (typically 12 V, 24 V, or 48 V). It is rechargeable at least by the CV converter. In the following, for the sake of non-limiting example, the auxiliary battery BS is considered to be a 12 V lithium-ion type.

[0030] The transmission chain has a powertrain which, in this case, is purely electric and therefore includes, in particular, an electric drive machine MME, a drive shaft AM, and a transmission shaft AT. The term "electric drive machine" here refers to an electric machine arranged to provide motor torque to move the vehicle V when supplied with electrical energy, and possibly to recover torque in the transmission chain.

[0031] The operation of the transmission chain (and therefore of the GMP) is supervised by a CS supervision computer.

[0032] The electric drive machine MME (here an electric motor) is coupled to the rechargeable battery BR, in order to be supplied with electrical energy, thus that possibly to supply this rechargeable BR battery with electrical energy, for example during a regenerative braking phase.

[0033] Furthermore, this electric drive machine MME is coupled to the motor shaft AM to supply it with motor torque by rotational drive. This motor shaft AM is here coupled to a gearbox RD which is also coupled to the transmission shaft AT, itself coupled to a first set Tl of driving wheels, preferably via a differential DV.

[0034] This first train Tl is located here in the front part PVV of the vehicle V. But in a variant this first train Tl could be the one which is here referenced T2 and which is located in the rear part PRV of the vehicle V.

[0035] It should be noted that in an alternative embodiment not illustrated, the first T1 and second T2 trains could both include drive wheels, in particular to allow a 4x4 type function.

[0036] The motor torque, which is delivered by the electric drive machine MME to the drive wheel(s), is a function of at least one torque information ic that represents the driver's intention in terms of motor torque. This intention can, for example, be defined by the driver by the depressment of the accelerator pedal PA. For example, the percentage of depressment of the accelerator pedal (PA) serves to define the torque information ic.

[0037] The operation of the electric drive machine MME can be controlled by a machine computer CM which is supervised by the supervisory computer CS.

[0038] The CV converter is also responsible, here, during the driving phases of the vehicle V, for converting part of the electrical current stored in the rechargeable battery BR to supply converted electrical current to the on-board network RB and the auxiliary battery BS (to recharge it).

[0039] The rechargeable battery BR, which here powers the electric drive unit MME, constitutes a main (or traction or power) battery. It may, for example, include electrical energy storage cells, possibly electrochemical (e.g., lithium-ion (or Li-ion), Ni-MH, or Ni-Cd). Also, for example, the rechargeable battery BR may be of the low-voltage type (typically 450 V, for illustrative purposes). But it could also be of the medium-voltage or high-voltage type.

[0040] Furthermore, the rechargeable battery BR is (here) associated with a battery case BB which includes, in particular, an interface (or isolation) device, voltage / current measurement means, and a battery computer. For example, the rechargeable battery BR and the battery case BB can form part of a battery assembly (or "pack").

[0041] The CFI control unit controls at least the traction control (or anti-slip) function. For example, this traction control function may be of the ASR (Acceleration Slip Regulation) type. But it could also be of the TCS (Traction Control System) type, for example.

[0042] This slip control function is designed to act on the electric drive machine MME, for example by transmitting to its machine computer CM speed commands cr2 or torque commands.

[0043] It should also be noted that in the example illustrated, but not limited to, in [Fig. 1], the vehicle V also includes a distribution box BD to which the auxiliary battery BS, the converter CV, and the on-board network RB are coupled. This distribution box BD is responsible for distributing the electrical energy stored in the auxiliary battery BS or produced by the converter CV into the on-board network RB to power the electrical components (or equipment) connected to the on-board network RB, according to power demands received (in particular from the powertrain control unit CS).

[0044] As mentioned above, the invention proposes in particular a control method intended to allow control of the torque that is transmitted by the drive wheels of the vehicle V in the event of a request to deactivate the slip control function by the driver.

[0045] This (control) method can be implemented at least partially by the DC control device (illustrated at least partially in Figures 1 and 2), which for this purpose comprises at least one PR1 processor, for example a digital signal processor (or DSP), and at least one MD memory. This DC control device can therefore be implemented as a combination of electrical or electronic circuits or components (or "hardware") and software modules (or "software"). By way of example, it could be a microcontroller.

[0046] The MD memory is random access memory (RAM) to store instructions for the implementation by the PR1 processor of at least part of the control process. The PR1 processor may comprise integrated (or printed) circuits, or several integrated (or printed) circuits connected by wired or wireless connections. An integrated (or printed) circuit is defined as any type of device capable of performing at least one electrical or electronic operation.

[0047] In the example illustrated, but not limited to, in Figures 1 and 2, the DC control device is part of the CFI computer (controlling at least the slip control function). However, this is not mandatory. Indeed, the DC control device could comprise its own dedicated computer, which is then coupled to the CFI computer, or it could be part of another computer installed in the vehicle V and performing at least one other function, for example.

[0048] As illustrated non-limitingly in [Fig.3], the (control) method according to the invention comprises a step 10-40 which is implemented each time the vehicle V moves and its slip control function is requested to be deactivated in a substep 10.

[0049] Step 10-40 of the method includes a substep 40 in which, if the driver requests the deactivation of the slip control function, the slip control function is operated (for example, the DC control device triggers operation of) in a specific mode in which it links the speed setpoint cr2 of the electric drive machine MME to the torque information ic. This controls the torque cri transmitted by the drive wheels of the vehicle V in the event that the slip control function is deactivated.

[0050] Thus, the slip control function simulates the behavior of a combustion engine when the slip control function is deactivated, allowing the driver to modulate the torque transmitted to the drive wheels because the motor torque supplied by the electric drive machine (EDM) is now progressive. Therefore, there is no longer a risk of significant wheel slippage if the slip control function is deactivated.

[0051] It should be noted that in the specific mode the driver is not informed that the traction control function has not been effectively deactivated.

[0052] For example, and as illustrated non-limitingly in [Fig.3], step 10-40 may include a substep 30 in which, in the specific mode, the slip control function (e.g., the DC control device) can determine the difference df between the torque information ic and the torque ctl that is transmissible by the drive wheels without loss of traction, i.e., df = ic - ctl.

[0053] Then, if this difference df is positive (i.e., df > 0, or ic > ctl), in substep 40 in the specific mode, the slip control function (for example, the DC control device) can determine at least one speed setpoint cr2 of the electric drive machine MME that is a function of this determined difference df. It will be understood that if ic > ctl, the (concerned) drive wheels slip. The (each) speed setpoint cr2 is then transmitted to the machine computer CM so that it can use it to operate the electric drive machine MME.

[0054] For example, in substep 40 in the specific mode, the slip control function (e.g., the DC control device) can determine a maximum speed setpoint cr2max of the electric drive machine MME that is a function of the determined difference df. In this case, the machine control unit CM is responsible for operating the electric drive machine MME at a speed that is less than or equal to the maximum speed setpoint cr2max.

[0055] But in an alternative embodiment the slip control function (for example the DC control device) could determine a non-maximum operating speed setpoint.

[0056] Also for example, in substep 40 in the specific mode the slip control function (for example the DC control device) can determine the maximum speed setpoint cr2max, or the speed setpoint cr2, of the electric drive machine MME in proportion to the determined difference df.

[0057] It should be noted that other, more sophisticated functions than a proportional function can be used to determine the maximum operating setpoint cr2max, or the operating setpoint cr2, as a function of the difference determined df.

[0058] Also, for example, and as illustrated non-limitingly in [Fig.3], step 10-40 may include a substep 20 in which, in the specific mode, the slip control function (for example, the DC control device) can determine the torque ctl, transmissible by the drive wheels without loss of traction, as a function of the torque ct2 transmitted by the drive wheels and an ipa information that is representative of the loss of traction of at least one drive wheel.

[0059] The torque ct2 (transmitted by the drive wheels) can, for example, be measured (or estimated) at the axle (here) of the front axle Tl by at least one sensor. The ipa information is estimated based (in particular) on the respective rotational speeds of the drive wheels (in question).

[0060] It should be noted that in substep 10 of step 10-40, the request to deactivate the traction control function can result from a dedicated action by the driver and / or from the driver's selection of a specific vehicle drive mode V. This dedicated action can, for example, be performed using a control device (dedicated or not) or by selecting an option displayed on a vehicle screen (for example, the central instrument cluster screen).

[0061] It should also be noted, as illustrated but not limited to [Fig. 2], that the CFI computer (or the DC control device computer) may also include a mass memory MM1, in particular for storing the torque information ic and the torque ctl and any torque ct2 and information ipa, as well as any intermediate data involved in all its calculations and processing. Furthermore, this CFI computer (or the DC control device computer) may also include an input interface IE for receiving at least the information signaling the deactivation of the slip control function, the torque information ic and the torque ctl and any torque ct2 and information ipa, for use in calculations or processing, possibly after having been shaped and / or demodulated and / or amplified, in a manner known per se, by means of a digital signal processor. PR2. In addition, this CFI computer (or the DC control device computer) may also include an IS output interface, in particular to deliver a message (or command) containing the minimum speed setpoint cr2min and maximum speed setpoint cr2max or the speed setpoint cr2.

[0062] It will also be noted that the invention also proposes a computer program product (or computer program) comprising a set of instructions which, when executed by processing means of the type of electronic circuits (or hardware), such as for example the PR1 processor, is suitable for implementing the control method described above to control in the vehicle V the torque cri transmitted by the drive wheels in the event of a request to deactivate the slip control function by the driver.

Claims

Demands

1. A control method for a land vehicle (V) comprising i) an electric drive machine (EDM) adapted to deliver for drive wheels a motor torque as a function of torque information representing a driver's intention, and ii) a slip control function adapted to act on said electric drive machine (EDM), characterized in that it comprises a step (10-40) in which, in the event of a request to deactivate said slip control function by said driver, said slip control function is operated in a specific mode in which it subordinates a speed setpoint of said electric drive machine (EDM) to said torque information.

2. Method according to claim 1, characterized in that in said step (10-40) in said specific mode said slip control function determines a difference between said torque information and a torque transmissible by said drive wheels without loss of adhesion, then if this difference is positive said slip control function determines at least one speed setpoint of said electric drive machine (EDM) as a function of said difference determined.

3. Method according to claim 2, characterized in that in said step (10-40) in said specific mode said slip control function determines a maximum speed setpoint of said electric drive machine (EDM) as a function of said difference determined.

4. Method according to claim 2 or 3, characterized in that in said step (10-40) in said specific mode said slip control function determines each speed setpoint of said electric drive machine (EDM) in proportion to said determined difference.

5. A method according to any one of claims 2 to 4, characterized in that in said step (10-40) in said specific mode said slip control function determines said torque transmissible by said drive wheels without loss of grip as a function of a torque transmitted by said drive wheels and information representative of a loss of grip of at least one drive wheel.

6. A method according to any one of claims 1 to 5, characterized in that in said step (10-40) said request to deactivate the traction control function results from a dedicated action of said driver and / or a selection by said driver of a specific drive mode of said vehicle (V).

7. Product computer program comprising a set of instructions which, when executed by processing means, is suitable for implementing the control method according to any one of claims 1 to 6, in a land vehicle (V) comprising i) an electric drive machine (EDM) suitable for delivering to drive wheels a motor torque as a function of torque information representative of a driver's intention, and ii) a slip control function suitable for acting on said electric drive machine (EDM), to control a torque transmitted by said drive wheels in the event of a request to deactivate said slip control function by said driver.

8. Control device (DC) for a land vehicle (V) comprising i) an electric drive machine (EDM) adapted to deliver for drive wheels a motor torque as a function of torque information representing a driver's intention, and ii) a slip control function adapted to act on said electric drive machine (EDM), characterized in that it comprises at least one processor (PR1) and at least one memory (MD) arranged to perform the operations consisting, in the event of a request to deactivate said slip control function by said driver, of triggering a control of a speed setpoint of said electric drive machine (EDM) on said torque information by said slip control function.

9. Land vehicle (V) comprising i) an electric drive machine (EDM) capable of delivering to drive wheels a motor torque as a function of torque information representative of a driver's intent, and ii) a slip control function capable of acting on said electric drive machine (EDM), characterized in that it further comprises a control device (DC) according to claim 8.

10. Land vehicle according to claim 9, characterized in that said control device (DC) is part of a computer (CFI) controlling said slip control function.

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