PRECISE PARAMETRIC CONTROL OF THE TORQUE REFERENCE OF A VEHICLE'S CLUTCH

Abstract

A control method is implemented in a vehicle comprising a thermal engine coupled to a gearbox via a hydraulically operated clutch, designed to deliver successive clutch torques defined by successive torque setpoints. This method includes a step (10-30) in which a limiting torque setpoint gradient between the last and next torque setpoints is determined based on an estimate of the current temperature of oil circulating in the hydraulic circuit. The next torque setpoint is then determined based on this determined limiting torque setpoint gradient. Figure 3.

Description

Title of the invention: PRECISE PARAMETRIC CONTROL OF THE TORQUE SETPOINT OF A VEHICLE CLUTCH Technical field of the invention

[0001] The invention relates to vehicles comprising a powertrain (or GMP) comprising a thermal motor coupled to a gearbox via a hydraulic circuit clutch, and more precisely the control of the torque setpoint of such a clutch. State of the art

[0002] Many vehicles, possibly of the automobile type, include a powertrain (or GMP) which comprises at least one thermal motor coupled to a gearbox via a hydraulic circuit clutch. It will be noted that the GMP can be hybrid, and in this case it includes not only at least one thermal motor, but also at least one electric motor.

[0003] In certain GMPs, the operation of the clutch is controlled by a torque setpoint which is determined by the GMP supervision computer, and the operation of the thermal engine is controlled either by a speed setpoint when the clutch is slipping, or by a torque setpoint when the clutch is in its coupling (or closed) position, the speed or torque setpoint also being determined by the GMP supervision computer.The clutch torque setpoint is used at all times to define the level of coupling / decoupling between the thermal engine and the gearbox, and therefore serves to couple the thermal engine to the wheels and to meet various needs such as energy optimization, pollution control, a level of performance, management of stability or the acoustic or vibration level, organic protections, passenger compartment or organic thermal (such as for example the start of movement (or "take-off") of the vehicle by means of the thermal engine).

[0004] In a clutch with a hydraulic circuit, the level of coupling / decoupling depends on the hydraulic pressure which is imposed in the hydraulic circuit, which is in theory defined by a hydraulic pressure setpoint resulting from the conversion of the clutch torque setpoint by a computer controlling the clutch and receiving the latter from the GMP supervision computer.

[0005] A disadvantage of this mode of operation lies in the fact that the effective hydraulic pressure in the hydraulic circuit depends on the viscosity of the oil present in the latter at the time in question, and therefore the same pressure setpoint hydraulic (or clutch torque setpoint) can cause different levels of coupling / decoupling depending on the viscosity. This can notably cause under-use or over-use of an on-board electrical system which can, for example, lead to a degradation of a desired optimization (such as fuel consumption or pollution control).

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

[0007] For this purpose, it proposes in particular a control method intended to be implemented in a vehicle comprising a powertrain comprising a thermal engine coupled to a gearbox via a hydraulic circuit clutch and capable of delivering successive clutch torques defined respectively by successive torque setpoints.

[0008] This control method is characterized by the fact that it comprises a step in which a limit torque setpoint gradient is determined between last and next torque setpoints as a function of an estimate of a current temperature of an oil circulating in the hydraulic circuit, then the next torque setpoint is determined as a function of this determined limit torque setpoint gradient.

[0009] By taking into account the current temperature of the oil circulating in the hydraulic circuit of the clutch (and representative of the current viscosity of this oil), we are sure that the next torque setpoint will actually correspond to the desired hydraulic pressure and therefore to the desired coupling / decoupling level of the clutch.

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

[0011] - in its step, we can determine the limit torque setpoint gradient in function, in addition, of the last torque instruction;

[0012] - in its step, we can determine the gradient of the limit torque setpoint in function, in addition, of a driving mode chosen by a driver of the vehicle;

[0013] - in its step, we can determine the limit torque setpoint gradient in function of data stored in at least one lookup table.

[0014] The invention also proposes a computer program product comprising a set of instructions which, when executed by processing means, is capable of implementing a control method of the type presented above, in a vehicle comprising a powertrain comprising a thermal engine coupled to a gearbox via a hydraulic circuit clutch and capable of delivering successive clutch torques defined respectively by successive torque setpoints, to control the torque setpoint.

[0015] The invention also proposes a control device intended to equip a vehicle comprising a powertrain comprising a thermal engine coupled to a gearbox via a hydraulic circuit clutch and capable of delivering successive clutch torques defined respectively by successive torque setpoints.

[0016] This control 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 of determining a limit torque setpoint gradient between last and next torque setpoints as a function of an estimation of a current temperature of an oil circulating in the hydraulic circuit, then determining the next torque setpoint as a function of this determined limit torque setpoint gradient.

[0017] The invention also proposes a vehicle, possibly of the automobile type, and comprising, on the one hand, a powertrain comprising a thermal engine coupled to a gearbox via a hydraulic circuit clutch and capable of delivering successive clutch torques defined respectively by successive torque setpoints, and, on the other hand, a control device of the type presented above.

[0018] For example, the powertrain may also include an electric motor that is installed between the clutch and the gearbox and capable of providing another torque. 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 control device according to the invention and a hybrid GMP transmission chain and associated with a supervision computer,

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

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

[0023] [Fig.4] schematically illustrates within a diagram examples of temporal evolution of a clutch torque setpoint (curve a1), of a limit torque setpoint gradient (curve a2) and of a torque actually delivered by the clutch (curve a3), when the invention is implemented. Detailed description of the invention

[0024] The invention aims in particular to propose a control method, and a associated DC2 control device, intended to allow precise parametric control of the torque delivered by the EM clutch ensuring the coupling / decoupling between a thermal MMT motor machine and a BV gearbox of a powertrain (or GMP) of a 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 at least with a thermal motor. Thus, it concerns land vehicles (utility vehicles, camper vans, minibuses, coaches, trucks, motorcycles, road machinery, construction machinery, agricultural machinery, leisure machinery (snowmobile, kart), tracked machinery, trains and trams, for example), aircraft and boats.

[0026] Furthermore, it is considered in the following, by way of non-limiting example, that the GMP is hybrid, and therefore comprises in particular a thermal motor and an electric motor. But the invention is not limited to this type of GMP. It in fact relates to any type of GMP comprising at least one thermal motor.

[0027] [Fig.l] schematically shows a vehicle V comprising a hybrid GMP transmission chain (and therefore in particular with a thermal motor MMT and an electric motor MME), a supervision computer CS, a clutch computer CE, a power supply battery BA, and a control device DC2 according to the invention.

[0028] As illustrated, the transmission chain also comprises, here, a drive shaft AM, a clutch EM with hydraulic circuit, a coupling device DC1, a gearbox BV, and a transmission shaft AT.

[0029] The operation of the transmission chain (and therefore of the GMP) is supervised by a CS supervision computer.

[0030] The thermal motor MMT comprises a crankshaft (not shown) which is fixedly secured to the motor shaft AM in order to drive the latter (AM) in rotation. This thermal motor MMT is capable of operating according to a speed defined by a speed setpoint determined by the supervision computer CS. In addition, it (MMT) is capable of being coupled to a gearbox BV, having another speed as input, via at least the clutch EM.

[0031] This clutch EM is arranged so as to deliver a first torque, defined by a clutch torque setpoint cce determined by the supervision computer CS, for at least one train T1 of driving wheels, when it is in its coupled position and therefore when it couples the thermal driving machine MMT to the gearbox BV. It will be noted that this clutch torque setpoint cce is transmitted by the cal supervisory controller CS to the clutch computer CE which controls the operation of the clutch EM and which converts this clutch torque setpoint cce into a hydraulic pressure setpoint cph for the hydraulic circuit of the clutch EM.

[0032] For example, the train T1 can be located in the front part PVV of the vehicle V. It is preferably, and as illustrated, coupled to the transmission shaft AT via a differential (here front) DV. But in a variant this train T1 could be that referenced T2 which is located in the rear part PRV of the vehicle V.

[0033] As a non-limiting example, the gearbox BV may be of the so-called “double clutch (or DCT)” type. However, the invention is not limited to this type of gearbox.

[0034] In the example illustrated without limitation, the crankshaft of the thermal motor MMT is also coupled to a belt CC, itself coupled to an alternator-starter AD which is supplied with electrical energy by a supply battery BA (and which can also recharge the latter (BA)). Thus, the alternator-starter AD can supply torque to the belt CC, which can supply this torque to the crankshaft.

[0035] It will be noted that this supply battery BA can, for example, be of the 48 V type. But this is not an obligation. Indeed, it could alternatively be of the 12 V, 24 V, or 400 V type for example.

[0036] The electric motor MME is, here, installed between the clutch EM and the gearbox BV, and is capable of providing a second torque, on command from the supervision computer CS. When the clutch EM has been placed in its coupled state (or completely closed) and the thermal motor MMT is in operation (and therefore has a non-zero speed), the clutch EM delivers a first torque which is added to a possible second torque provided by the electric motor MME, upstream of the gearbox BV. When the clutch EM has been placed in its uncoupled state (or completely open), only the electric motor MME can provide a second torque upstream of the gearbox BV.

[0037] The sum of the first and second torques gives upstream of the gearbox BV a third torque which is required by the supervision computer CS and representative of the acceleration desire of the driver of the vehicle V, which is for example defined by the percentage of depression of the accelerator pedal of the vehicle V.

[0038] It will be noted that in the example illustrated non-limitingly in [Fig.l] the clutch EM, the electric motor MME and the gearbox BV are part of a gearbox assembly EBV. But this is not an obligation.

[0039] It will also be noted that in the example illustrated non-limitingly in [Fig.l] the transmission chain also comprises a DC1 coupling device installed downstream EM clutch and MME electric motor and upstream of the BV gearbox. However, this is not a requirement. Furthermore, the DC1 coupling device is here part of the EBV gearbox assembly. However, this is not a requirement.

[0040] As mentioned above, the invention notably proposes a control method intended to allow precise parametric control of the first torque which is delivered by the EM clutch.

[0041] This (control) method can be implemented at least partially by the control device DC2 (illustrated at least partially in FIGS. 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 control device DC2 can therefore be produced in the form of a combination of electrical or electronic circuits or components (or "hardware") and software modules (or "software"). For example, it can 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 control 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 control device DC2 is part of the supervision computer CS. But this is not obligatory. Indeed, the control device DC2 could comprise its own dedicated computer, which is then coupled to the supervision computer CS, or could be part of another computer on board the vehicle V and providing at least one other function, for example.

[0044] As illustrated non-limitingly in [Fig. 3], the (control) method, according to the invention, comprises a step 10-30 which is implemented each time a clutch torque setpoint cce must be determined.

[0045] Step 10-30 of the method comprises a sub-step 20 in which one (the control device DC2) begins by determining a limit torque setpoint gradient gccl between the last cce(t) and next cce(t+l) torque setpoints as a function of an estimation of a current temperature of the oil circulating in the hydraulic circuit of the clutch EM. It will be understood that the last torque setpoint cce(t) is the very last torque setpoint having been determined for the clutch EM, while the next torque setpoint cce(t+l) is the torque setpoint which will very soon be determined for the clutch EM.

[0046] Furthermore, it will be noted that the estimation of the current temperature of the circulating oil in the hydraulic circuit of the EM clutch can be provided by a sensor present in the hydraulic circuit of the EM clutch. But this is not mandatory. In fact, the estimation of the current temperature of the oil circulating in the hydraulic circuit of the EM clutch can be provided by a sensor which is present in the gearbox BV, because the current temperature of the oil in the latter (BV) is equivalent to that of the oil in the hydraulic circuit.

[0047] Step 10-30 of the method also comprises a sub-step 30 in which the control device DC2 determines the next torque setpoint cce(t+l) as a function of the limit torque setpoint gradient gccl determined in sub-step 20.

[0048] The next torque setpoint cce(t+l) is determined as a function of a torque that is required upstream of the gearbox BV (here to rotate the drive wheels) and which is representative of the acceleration desire of the driver of the vehicle V, which is for example defined by the percentage of depression of the accelerator pedal of the vehicle V. It will be noted that in the case of a hybrid GMP, this torque required upstream of the gearbox BV can possibly be distributed between the clutch EM and the electric motor MME. The portion of torque to be delivered by the clutch EM (cce(t+l)) is then constrained by the limit torque setpoint gradient gccl just determined. In fact, it is at most equal to the sum of the previous (or last) torque setpoint cce(t) and the limit torque setpoint gradient gccl just determined.

[0049] The current temperature of the oil circulating in the hydraulic circuit of the EM clutch being representative of the current viscosity of this oil, taking it into account allows a determination of the next torque setpoint cce(t+l) which will actually correspond to the desired hydraulic pressure and therefore to the desired coupling / decoupling level of the EM clutch. There is therefore no longer any risk of causing under-use or over-use of an on-board electrical system.

[0050] For example, and as illustrated non-limitingly in [Fig. 3], step 10-30 of the method may comprise a sub-step 10 in which one (the control device DC2) may initially determine for the moment considered the estimation of the current temperature of the oil circulating in the hydraulic circuit of the clutch EM.

[0051] It will be noted that in sub-step 20 of step 10-30 one (the control device DC2) can determine the limit torque setpoint gradient gccl also as a function of the last torque setpoint cce(t). This makes it possible to have even more precise control of the torque cde delivered by the clutch EM, in particular during certain critical phases such as the start of the effective delivery of torque cde by the clutch EM and the approach to a target setpoint (because the speed difference between the thermal motor MMT and the primary shaft AP of the gearbox BV is small and therefore in the event of a change in the direction of speed there is a risk of jolts).

[0052] This is in particular what can be observed in the diagram of [Fig.4] which illustrates examples of temporal evolution of the clutch torque setpoint cce (curve al), of the limit torque setpoint gradient gccl (curve a2) and of the torque cde which is actually delivered by the clutch EM (curve a3), when the invention is implemented.

[0053] It will also be noted that in sub-step 20 of step 10-30 one (the control device DC2) can determine the limit torque setpoint gradient gccl also as a function of a driving mode chosen by the driver of the vehicle V, for example from an economical driving mode, a sporty driving mode, and a normal driving mode. This makes it possible to improve driving pleasure. Indeed, one could for example have a greater limit torque setpoint gradient gccl in sporty mode than in normal or economical mode, so as to have more direct accelerations in sporty mode.

[0054] It will also be noted that in sub-step 20 of step 10-30 one (the control device DC2) can determine the limit torque setpoint gradient gccl as a function of data which are stored in at least one correspondence table, for example previously determined in the factory (or test center) for a vehicle similar to the vehicle V.

[0055] In the least sophisticated case (only taking into account the oil temperature), the correspondence table establishes a correspondence between oil temperatures and gradients of limit torque setpoint gccl. In a more sophisticated case (taking into account the oil temperature and the last torque setpoint cce(t)), the correspondence table establishes a correspondence between pairs of oil temperature and clutch torque setpoint) and gradients of limit torque setpoint gccl. In another (still) more sophisticated case (taking into account the oil temperature and the last torque setpoint cce(t) and / or the driving mode), the correspondence table establishes a correspondence between multiplets of oil temperature and clutch torque setpoint and / or driving mode) and gradients of limit torque setpoint gccl.Note that in the latter case, we can also use correspondence tables which are associated respectively with the different driving modes.

[0056] The invention offers several advantages, including:

[0057] - an improvement in driving pleasure (in particular by avoiding shocks or- strokes and stalls of the thermal motor MMT),

[0058] - robustness of the control (or piloting) of the EM clutch thanks to the improvement couple monitoring in all life situations,

[0059] - an absence of degradation of a target optimization (for example relating to the fuel consumption or pollution control),

[0060] - control of stored electrical energy.

[0061] It will also be noted, as illustrated non-limitingly in [Fig. 2], that the supervision computer CS (or the computer of the control device DC2) can also comprise a mass memory MM1, in particular for storing each estimate of the current temperature of the oil circulating in the hydraulic circuit of the clutch EM and the possible driving mode chosen, as well as any intermediate data involved in all its calculations and processing.Furthermore, this supervision computer CS (or the computer of the control device DC2) can also comprise an input interface IE for receiving at least each estimate of the current temperature of the oil circulating in the hydraulic circuit of the clutch EM and the possible driving mode chosen, 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 supervision computer CS (or the computer of the control device DC2) can also comprise an output interface IS, in particular for delivering each message containing the next determined torque setpoint cce(t+l).

[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 electronic circuit (or hardware) type, such as for example the processor PR1, is capable of implementing the control method described above to parametrically and precisely control the torque setpoint cce for the clutch EM of the vehicle V.

Claims

Claims

1. Control method for a vehicle (V) comprising a powertrain comprising a thermal motor (MMT) coupled to a gearbox (BV) via a clutch (EM) with a hydraulic circuit and capable of delivering successive clutch torques defined respectively by successive torque setpoints, characterized in that it comprises a step (10-30) in which a limit torque setpoint gradient is determined between last and next torque setpoints as a function of an estimate of a current temperature of an oil circulating in said hydraulic circuit, then said next torque setpoint is determined as a function of said determined limit torque setpoint gradient.

2. Method according to claim 1, characterized in that in said step (10-30) said limit torque setpoint gradient is determined as a function, in addition, of said last torque setpoint.

3. Method according to claim 1 or 2, characterized in that in said step (10-30) said limit torque setpoint gradient is determined as a function, in addition, of a driving mode chosen by a driver of said vehicle (V).

4. Method according to one of claims 1 to 3, characterized in that in said step (10-30) said limit torque setpoint gradient is determined as a function of data stored in at least one correspondence table.

5. Computer program product comprising a set of instructions which, when executed by processing means, is capable of implementing the control method according to one of claims 1 to 4, in a vehicle (V) comprising a powertrain comprising a thermal motor machine (MMT) coupled to a gearbox (BV) via a clutch (EM) with a hydraulic circuit and capable of delivering successive clutch torques defined respectively by successive torque setpoints, to control said torque setpoint.

6. Control device (DC2) for a vehicle (V) comprising a powertrain comprising a thermal motor (MMT) coupled to a gearbox (BV) via a clutch (EM) with a hydraulic circuit and capable of delivering clutch torques defined by successive torque setpoints, characterized in that it comprises at least one processor (PR1) and at least one memory (MD) arranged to carry out the operations consisting of determining a limit torque setpoint gradient between last and next torque setpoints as a function of an estimate of a current temperature of an oil circulating in said hydraulic circuit, then determining said next torque setpoint as a function of said determined limit torque setpoint gradient.

7. Vehicle (V) comprising a powertrain comprising a thermal motor (MMT) coupled to a gearbox (BV) via a clutch (EM) with a hydraulic circuit and capable of delivering successive clutch torques defined respectively by successive torque setpoints, characterized in that it further comprises a control device (DC2) according to claim 6.

8. Vehicle according to claim 7, characterized in that said powertrain also comprises an electric motor (MME) installed between said clutch (EM) and said gearbox (BV) and capable of providing another torque.

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

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