DETERMINATION OF THE TORQUE INSTITUTION OF A VEHICLE'S GMP, ADAPTED TO THE CURRENT DIRECTION OF TRAVEL

Abstract

A method is implemented in a vehicle comprising a GMP capable of providing an engine torque, defined by a torque setpoint depending on a current torque request, to move this vehicle. This method comprises a step (10-30) in which, in the event of a need to move the vehicle in a chosen direction, the torque setpoint is determined as a function of the current torque request and a current actual speed of the vehicle having a sign determined relative to a predefined direction of movement of the vehicle. Figure 3

Description

Title of the invention: DETERMINATION OF THE TORQUE INSTITUTION OF A VEHICLE GEARBOX, ADAPTED TO THE CURRENT DIRECTION OF TRAVEL Technical field of the invention

[0001] The invention relates to vehicles comprising a powertrain capable of providing engine torque to move them, and more precisely to the determination in such vehicles of the torque setpoint defining this engine torque to be provided. State of the art

[0002] Motorized vehicles, possibly of the automobile type, comprise a powertrain (or GMP) comprising at least one prime mover capable of providing engine torque to move them. It will be noted that the (each) prime mover of the GMP may be thermal or non-thermal.

[0003] As is known to those skilled in the art, in many motor vehicles the engine torque that the GMP must provide is defined by a torque setpoint which is a function of a current torque demand and generally determined by the GMP supervision computer. For example, in a motor vehicle the torque demand can be constructed from the percentage of depression of the accelerator pedal which defines the desire of the driver of the vehicle in terms of acceleration.

[0004] Currently, the torque setpoint is determined by means of a table (or mapping) establishing a correspondence between pairs, comprising a value representative of a torque request and an absolute value of vehicle speed, and torque setpoints. Consequently, each torque setpoint is determined according to the absolute value of the current speed of the vehicle (which is always available in the vehicle), regardless of the direction of movement of the latter.

[0005] This can be a disadvantage in certain situations in the life of a vehicle, such as when the vehicle is reversing while the driver requests that it move forward. Such a situation can occur in particular on a sloping road which causes the vehicle to move backward. In this type of situation, if the driver is too slow to react, the vehicle picks up speed (in reverse) and therefore the torque setpoint determined at the same pressure on the accelerator pedal is even lower, which forces the driver to press hard on the accelerator pedal to move the vehicle in the right direction (i.e. forward).

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

[0007] It proposes in particular for this purpose a determination (or calculation) method intended to be implemented in a vehicle comprising a powertrain capable of providing engine torque, defined by a torque setpoint depending on a current torque request, to move this vehicle.

[0008] This determination method is characterized by the fact that it comprises a step in which, in the event of a need to move the vehicle in a chosen direction, the torque setpoint is determined as a function of the current torque demand and a current actual speed of the vehicle having a sign determined relative to a predefined direction of movement of the vehicle.

[0009] Thus, each torque instruction is now adapted to the vehicle's operating situation, and therefore there is no longer any risk that the driver will be forced to press hard on the accelerator pedal to move his vehicle forward or backward.

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

[0011] - in its step, the predefined direction of movement can be a direction of movement in forward motion of the vehicle;

[0012] - in a first embodiment, in its step, the instruction can be determined torque by means of a table establishing a correspondence between pairs, comprising a value representative of a torque request and an actual speed, and torque instructions;

[0013] - in a second embodiment, in its step, the instruction can be determined of torque by means, on the one hand, of a first table establishing a correspondence between pairs, comprising a value representative of a torque request and a positive real speed, and torque instructions, and, on the other hand, of a second table establishing a correspondence between pairs, comprising a value representative of a torque request and a negative real speed, and torque instructions.

[0014] The invention also provides a computer program product comprising a set of instructions which, when executed by processing means, is capable of implementing a determination (or calculation) method of the type presented above, in a vehicle comprising a powertrain capable of providing an engine torque, defined by a torque setpoint depending on a current torque demand, to move this vehicle, to determine this torque setpoint.

[0015] The invention also proposes a calculation device intended to equip a vehicle comprising a powertrain capable of providing an engine torque, defined by a torque setpoint depending on a current torque demand, to move this vehicle.

[0016] This calculation device is characterized by the fact that it comprises at least one processor and at least one memory arranged to carry out the operations consisting, in the event of the need to move the vehicle in a chosen direction, in determining the setpoint of torque as a function of the current torque demand and a current actual speed of the vehicle having a sign determined relative to a predefined direction of movement of the vehicle.

[0017] The invention also proposes a vehicle, possibly of the automobile type, and comprising, on the one hand, a powertrain capable of providing an engine torque, defined by a torque setpoint depending on a current torque demand, to move it, and, on the other hand, a calculation device of the type presented above.

[0018] For example, this vehicle may also include a supervision computer capable of supervising the operation of the powertrain and comprising the calculation device. Brief description of the figures

[0019] Other characteristics and advantages of the invention will appear on examining the detailed description below, and the appended drawings, in which:

[0020] [Fig. 1] schematically and functionally illustrates an exemplary embodiment of a vehicle comprising a calculation device according to the invention and a purely electric GMP transmission chain supervised by a supervision computer,

[0021] [Fig.2] schematically and functionally illustrates an exemplary embodiment of a supervision calculator comprising an exemplary embodiment of a calculation device according to the invention,

[0022] [Fig.3] schematically illustrates an example of an algorithm implementing a determination method according to the invention, and

[0023] [Fig.4] schematically illustrates within a diagram examples of evolution of the torque setpoint determined in the absence of the invention (cl) and in the presence of the invention (c2) as a function of the actual speed of the vehicle, for the same percentage of depression of the accelerator pedal. Detailed description of the invention

[0024] The invention aims in particular to propose a determination method, and an associated calculation (or determination) device DC, intended to enable the determination in a motorized vehicle V of a torque setpoint cc defining the engine torque cm that the powertrain (or GMP) must provide and adapted to the current direction of movement of the vehicle V.

[0025] In the following, it is considered, by way of non-limiting example, that the vehicle V is of the automobile type. It is for example a car, as illustrated in [Fig.l]. But the invention is not limited to this type of vehicle. It in fact concerns any type of vehicle comprising a GMP transmission chain, and therefore land vehicles, boats and aircraft.

[0026] Furthermore, it is considered in the following, by way of non-limiting example, that the powertrain (or GMP) is purely electric (and therefore comprises at least one electric MME motor machine). But the invention relates to any type of GMP, and in particular purely thermal GMPs and hybrid GMPs (thermal and non-thermal).

[0027] Furthermore, it is considered in the following, by way of non-limiting example, that the electric motor MME is supplied with electrical energy by a main (or “traction” or even “power”) battery BP, rechargeable at least during recharging phases. But the (each) electric motor MME could be supplied with electrical energy by a fuel cell.

[0028] [Fig.l] schematically shows a vehicle V comprising an all-electric GMP transmission chain (and therefore comprising at least one electric MME motor machine), a supervision computer CS, a service battery BS, an on-board network RB, a main battery BP, a converter CV, an accelerator pedal PA, and a calculation device DC according to the invention.

[0029] The CV converter is of the DC / DC type (“Direct Current / Direct Current”). It is therefore responsible for converting a direct current from a first voltage to a second voltage.

[0030] The service battery BS is responsible for supplying electrical energy to an on-board network RB, in addition, here, to that supplied by the CV converter powered by the main battery BP, and sometimes instead, here, of this CV converter. For example, this service battery BS can be arranged in the form of a very low voltage type battery (typically 12 V, 24 V or 48 V). It is rechargeable at least by the (current) converter CV. It is considered in the following, by way of non-limiting example, that the service battery BS is of the 12 V Lithium-ion type.

[0031] Here, the term “on-board network RB” means an electrical power supply network to which electrical (or electronic) equipment (or components) that consume electrical energy are coupled.

[0032] The transmission chain has a GMP which is, here, purely electric and therefore which comprises, in particular, an electric motor MME, a motor shaft, and a transmission shaft AT. Here, the term "electric motor" means an electric machine arranged so as to provide a motor torque cm, defined by a torque setpoint cc, to move the vehicle V when it is supplied with electrical energy (here) by the main battery BP (we then speak of providing a positive output torque), as well as possibly to recover torque, for example in a regenerative braking phase (we then speak of providing a negative output torque).

[0033] The operation of the GMP is supervised by a CS supervision computer.

[0034] The driving machine MME is coupled to the motor shaft AM, to provide it with motor torque cm by rotational drive. This motor shaft AM is here coupled to a reducer RD which is also coupled to the transmission shaft AT, itself coupled to a train Tl of driving wheels, preferably via a differential Dl.

[0035] It will be noted that the train T1 is here located in the front part PVV of the vehicle V. But in a variant this train T1 could be that referenced T2 which is located in the rear part PRV of the vehicle V.

[0036] The CV converter can also be responsible during the driving phases of the vehicle V for converting part of the electric current stored in the main battery BP to supply the on-board network RB and the service battery BS with converted electric current (to recharge it).

[0037] The main battery (or traction or even power) BP may, for example, comprise electrical energy storage cells, possibly electrochemical (for example of the lithium-ion (or Li-ion) or Ni-Mh or Ni-Cd type). Also for example, the main battery BP may be of the low voltage type (typically 450 V for illustration purposes). But it could be of the medium voltage or high voltage type.

[0038] It will also be noted that in the example illustrated non-limitingly in [Fig. 1] the vehicle V also comprises a distribution box BD to which the service battery BS, the converter CV and the on-board network RB are coupled. This distribution box BD is responsible for distributing in the on-board network RB the electrical energy stored in the service battery BS or produced by the converter CV, for the supply of the electrical components (or equipment) coupled to the on-board network RB according to power supply requests received (in particular from the supervision computer CS of the GMP).

[0039] It will also be noted, as illustrated in [Fig.l], that the vehicle V also comprises an accelerator pedal PA actuable (here) by a foot of the driver of the vehicle V. It has a depression percentage pe from which a torque demand dcc representative of the driver's desire in terms of acceleration can be defined.

[0040] As mentioned above, the invention proposes in particular a determination (or calculation) method intended to enable the determination in the vehicle V of the torque setpoint cc defining the engine torque cm that the GMP (and more precisely here the (electric) motor machine MME) must provide.

[0041] This (determination) method can be implemented at least partially by the calculation (or determination) device DC (illustrated at least partially in figures 1 and 2) which comprises for this purpose at least one processor PR1, for example a digital signal processor (or DSP (“Digital Signal Processor”)), and at least one memory MD. This DC computing device can therefore be implemented in the form of a combination of electrical or electronic circuits or components (or "hardware") and software modules (or "software"). For example, it could be a microcontroller.

[0042] The memory MD is live in order to store instructions for the implementation by the processor PR1 of at least part of the determination (or calculation) method. The processor PR1 may comprise integrated (or printed) circuits, or several integrated (or printed) circuits connected by wired or wireless connections. An integrated (or printed) circuit is understood to mean any type of device capable of carrying out at least one electrical or electronic operation.

[0043] In the example illustrated non-limitingly in Figures 1 and 2, the calculation device DC is part of the supervision computer CS. But this is not obligatory. Indeed, the calculation device DC could comprise its own dedicated computer, which is then coupled to the supervision computer CS, for example.

[0044] As illustrated non-limitingly in [Fig. 3], the method (of determination (or calculation)), according to the invention, comprises a step 10-30 which is implemented each time the GMP is in operation and therefore must receive a torque instruction cc defining the engine torque cm that it must provide.

[0045] Step 10-30 of the method comprises a sub-step 30 in which, in the event of a need to move the vehicle V in a chosen direction, the torque setpoint cc is determined (for example by the calculation device DC) as a function of the current torque request dcc and the current actual speed vr of the vehicle V, which has a sign (positive or negative) which is determined relative to a predefined direction of movement sdp of the vehicle V.

[0046] In other words, each torque setpoint cc is now determined according to the current direction of movement of the vehicle V, which allows it to be adapted to the real-life situation of the vehicle V, and in particular when it is on a sloping traffic lane which causes it to move backward while its driver requests that it move forward. There is therefore no longer any risk that the driver will be forced to press hard on the accelerator pedal PA to move his vehicle V forward on an uphill slope or to move his vehicle V backward on a downhill slope.

[0047] It will be noted that the sign (positive or negative) of the actual speed vr, which defines the current direction of movement of the vehicle V relative to the predefined direction of movement sdp, can, for example, be determined by a dedicated sensor equipping the transmission of the vehicle V or by the direction of rotation of the electric motor MME (in the case of an electric or hybrid GMP).

[0048] For example, and as illustrated non-limitingly in [Fig.3], step 10-30 may comprise a sub-step 10 in which one (for example the computing device DC) receives the current torque request dcc (representative of the driver's desire in terms of acceleration), which triggers the determination of the torque setpoint cc.

[0049] Also for example, and as illustrated non-limitingly in [Fig.3], step 10-30 can comprise a sub-step 20 in which one (for example the calculation device DC) can determine the current direction of movement of the vehicle V relative to the predefined direction of movement sdp, then the actual speed vr by attributing the sign of the determined current direction of movement to the absolute value of the current speed vv of the vehicle V (easily accessible in the latter (V)).

[0050] Also for example, in step 10-30 the predefined direction of movement sdp may be a forward direction of movement of the vehicle V. But an inverse convention may be used, namely a predefined direction of movement sdp which is the reverse direction of movement of the vehicle V.

[0051] At least two embodiments of the method can be envisaged for determining the torque setpoint cc.

[0052] In a first embodiment, in sub-step 30 of step 10-30 it is possible (for example the calculation device DC can) to determine the torque setpoint cc by means of a table (or mapping) which establishes a correspondence between pairs, comprising a value vl representative of a torque request and an actual speed, and torque setpoints. It will be noted that the value vl can, for example, be equal to the percentage of depression of the accelerator pedal PA. But this is not obligatory. Indeed, it could be equal to the torque request.

[0053] Thus, knowing the current value vl in the vehicle V and the current actual speed vr, we can easily determine the torque setpoint which corresponds to them in the table, which then becomes the determined torque setpoint cc.

[0054] In a second embodiment, in sub-step 30 of step 10-30 it is possible (for example the DC calculation device can) to determine the torque setpoint cc by means of first and second tables (or maps). The first table (or map) establishes a correspondence between pairs, comprising a value vl representative of a torque demand and a positive real speed, and torque setpoints. The second table establishes a correspondence between pairs, comprising a value vl representative of a torque demand and a negative real speed, and torque setpoints.

[0055] Thus, if the current actual speed vr is positive, the first table is used to determine the torque setpoint cc, and if the current actual speed vr is negative, the second table is used to determine the torque setpoint cc.

[0056] [Fig.4] schematically illustrates a diagram showing two examples of the evolution of the torque setpoints cc (in Nm) determined respectively in the absence of the invention (curve cl of the prior art) and in the presence of the invention (curve c2) as a function of the actual speed vr (in km / h) of the vehicle, and for the same percentage of depression of the accelerator pedal PA. As can be seen, for positive actual speeds vr the two curves cl and c2 have a significant common part. It is only when approaching the zero value of the actual speed vr that the curves cl and c2 begin to differ significantly. Then, when moving to negative actual speeds vr, the curve cl (prior art) becomes symmetrical to its positive part (with respect to the zero value) because in the prior art the absolute value of the vehicle speed is used, and therefore the more negative the actual speed becomes, the lower the torque setpoint cc becomes, which is not suitable for certain vehicle life situations.On the other hand, we see on curve c2 that the more the actual speed vr of the vehicle V becomes negative, the more the torque setpoint cc becomes important, which is well suited to real needs.

[0057] It will also be noted, as illustrated non-limitingly in [Fig. 2], that the supervision computer CS (or the computer of the calculation device DC) can also comprise a mass memory MM1, in particular for storing the current torque request dcc and the speed (with or without sign), as well as any intermediate data involved in all its calculations and processing. Furthermore, this supervision computer CS (or the computer of the calculation device DC) can also comprise an input interface IE for receiving at least the current torque request dcc and the speed (with or without sign) and possibly the direction of movement of the vehicle V, to use them in calculations or processing, possibly after having shaped and / or demodulated and / or amplified them, in a manner known per se, by means of a digital signal processor PR2.In addition, this CS supervision calculator (or the calculator of the DC calculation device) can also include an IS output interface, in particular to deliver a message (or order) containing the determined DC torque instruction.

[0058] 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 electronic circuit (or hardware) type, such as for example the processor PR1, is capable of implementing the determination (or calculation) method described above to determine in the vehicle V the torque setpoint cc defining the engine torque cm that the GMP must provide.

Claims

Claims

1. Method for determining a torque setpoint for a vehicle (V) comprising a powertrain capable of providing an engine torque, defined by a torque setpoint depending on a current torque demand, to move said vehicle (V), characterized in that it comprises a step (10-30) in which, in the event of a need to move said vehicle (V) in a chosen direction, said torque setpoint is determined as a function of said current torque demand and of a current actual speed of said vehicle (V) having a sign determined relative to a predefined direction of movement of said vehicle (V).

2. Method according to claim 1, characterized in that in said step (10-30) said predefined direction of movement is a forward direction of movement of said vehicle (V).

3. Method according to claim 1 or 2, characterized in that in said step (10-30) said torque setpoint is determined by means of a table establishing a correspondence between pairs, comprising a value representative of a torque request and an actual speed, and torque setpoints.

4. Method according to claim 1 or 2, characterized in that in said step (10-30) said torque setpoint is determined by means of i) a first table establishing a correspondence between pairs, comprising a value representative of a torque demand and a positive real speed, and torque setpoints, and ii) a second table establishing a correspondence between pairs, comprising a value representative of a torque demand and a negative real speed, and torque setpoints.

5. Computer program product comprising a set of instructions which, when executed by processing means, is capable of implementing the determination method according to one of claims 1 to 4, in a vehicle (V) comprising a powertrain capable of providing an engine torque, defined by a torque setpoint depending on a current torque request, to move said vehicle (V), to determine said torque setpoint.

6. Calculation device (DC) for determining a torque setpoint for a vehicle (V) comprising a powertrain capable of providing an engine torque, defined by a torque setpoint depending on a current torque demand, for moving said vehicle (V), ca- characterized in that it comprises at least one processor (PR1) and at least one memory (MD) arranged to carry out the operations consisting, in the event of a need to move said vehicle (V) in a chosen direction, in determining said torque setpoint as a function of said current torque request and a current actual speed of said vehicle (V) having a sign determined relative to a predefined direction of movement of said vehicle (V).

7. Vehicle (V) comprising a powertrain capable of providing an engine torque, defined by a torque setpoint depending on a current torque request, to move said vehicle (V), characterized in that it further comprises a calculation device (DC) according to claim 6.

8. Vehicle according to claim 7, characterized in that it comprises a supervision computer (CS) capable of supervising the operation of said powertrain and comprising said calculation device (DC).

9. Vehicle according to claim 7 or 8, characterized in that it is of the automobile type.

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