FR3145532A1 - CONTROL OF THE ENGINE SPEED OF A THERMAL DRIVE MACHINE OF A HYBRID GMP VEHICLE AT THE START OF TRAVEL - Google Patents

Abstract

A control method is implemented in a vehicle comprising a thermal engine operating at a first speed and coupled to a gearbox, having a second speed as input, via a coupling device, and an electric engine installed between the thermal engine and the coupling device and having available electrical power. This method comprises a step (10-40) in which, at the start of a movement of the vehicle with the thermal engine, the first speed is determined as a function of this available electrical power of the electric engine to limit the energy stored in the coupling device, and this available electrical power is used. Figure 3.

Description

CONTROL OF THE ENGINE SPEED OF A THERMAL DRIVE MACHINE OF A HYBRID GMP VEHICLE AT THE START OF TRAVEL Technical field of the invention

The invention relates to vehicles comprising a hybrid powertrain (or GMP), and more specifically to the control of the operation of such a thermal motor machine at the start of the movement of its vehicle.

State of the art

Some vehicles, possibly of the automobile type, include a hybrid powertrain (or GMP), i.e. comprising at least one thermal motor and at least one electric motor.

In some powertrains, the thermal engine is coupled to a gearbox via a first coupling device (such as a clutch), and the electric engine is installed between this thermal engine and this first coupling device. When the first coupling device is in its coupling position, it delivers a first torque which is a function of the first current engine speed of the thermal engine and/or a second torque delivered by the electric engine, and the gearbox has a second speed on its input. It should be noted that a second coupling device can also be provided between the thermal engine and the first coupling device, in order to allow coupling of the electric engine between the first and second coupling devices.

When the vehicle is on land and begins to move (while stationary) with its thermal engine previously coupled to its gearbox by its first coupling device, the first engine speed of its thermal engine is independent of the rotation speed of its drive wheels (coupled to its gearbox), which is proportional to the second speed at the input of its gearbox.

This vehicle life situation can prove stressful for its first coupling device, because the energy stored in the latter is a function of the power it dissipates, which is equal to the product of the first torque delivered by the first coupling device by the difference between the first and second speeds. This stored energy is all the more important as the torque that is required for the drive wheels and that results from the operation of the thermal engine is important. For example, obtaining such a torque at the drive wheels may require a first speed of the thermal engine equal to approximately 2000 revolutions per minute when significant performance is desired in terms of acceleration. Such a first speed quickly causes a significant amount of energy to be stored in the first coupling device, and therefore a rapid rise in temperature of the latter. Consequently, the first coupling device reaches its thermal limitation in a few seconds and therefore loses its coupling efficiency. Therefore, it may happen that it is not possible to start moving the vehicle when it is towing a loaded trailer and/or when it is placed on a steep uphill slope.

The invention is therefore intended in particular to improve the situation.

Presentation of the invention

For this purpose, it proposes in particular a control method intended to be implemented in a vehicle comprising a powertrain comprising, on the one hand, a thermal motor capable of operating according to a first speed and coupled to a gearbox, having a second speed as input, via a coupling device, and, on the other hand, an electric motor installed between the thermal motor and the coupling device and having available electrical power.

This control method is characterized by the fact that it comprises a step in which, when the vehicle starts moving with the thermal motor, the first speed is determined as a function of this available electrical power of the electric motor to limit energy stored in the coupling device, and this available electrical power is used.

Thus, if the electric motor can make sufficient electrical power available, the first speed can be reduced, because the reduction that this causes in the first torque delivered by the coupling device is compensated by this available electrical power.

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

- in its step, the first regime can be determined based on the available electrical power and a first required torque to be provided by the coupling device;

- in the presence of the first option, in its step, when the available electrical power corresponds to a second torque, which can be provided by the electric motor, equal to a percentage of the first required torque of between 20% and 60%, a first speed of between 1300 revolutions per minute and 1800 revolutions per minute can be determined;

- in the presence of the last sub-option, in its step, when the available electrical power corresponds to a second torque, which can be provided by the electric motor, equal to a percentage of the first required torque between 20% and 60%, a first speed equal to 1500 revolutions per minute can be determined;

- also in the presence of the last sub-option, in its step, when the available electrical power corresponds to a second torque, which can be provided by the electric motor, equal to a percentage of the first required torque less than 20%, a first regime can be determined which is suitable for obtaining the first required torque in the absence of a second torque.

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, on the one hand, a thermal engine capable of operating according to a first speed and coupled to a gearbox, having a second speed as input, via a coupling device, and an electric engine installed between the thermal engine and the coupling device and having available electrical power, for controlling the first speed when the vehicle starts moving with the thermal engine.

The invention also proposes a control device intended to equip a vehicle comprising a powertrain comprising, on the one hand, a thermal motor capable of operating according to a first speed and coupled to a gearbox, having a second speed as input, via a coupling device, and, on the other hand, an electric motor installed between the thermal motor and the coupling device and having available electrical power.

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, when the vehicle starts moving with the thermal motor, in determining the first speed as a function of this available electrical power of the electric motor to limit energy stored in the coupling device, and the use of this available electrical power is triggered.

The invention also proposes a vehicle, possibly of the automobile type, and comprising, on the one hand, a powertrain comprising a thermal engine capable of operating according to a first speed and coupled to a gearbox, having a second speed as input, via a coupling device, and an electric engine installed between the thermal engine and the coupling device and having available electrical power, and, on the other hand, a control device of the type presented above.

Brief description of the figures

Other characteristics and advantages of the invention will appear on examining the detailed description below, and the attached drawings, in which:

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,

schematically and functionally illustrates an exemplary embodiment of a supervision calculator comprising an exemplary embodiment of a control device according to the invention,

schematically illustrates an example of an algorithm implementing a control method according to the invention, and

schematically illustrates in a diagram an example of the evolution of the first torque (in Newton meters (or Nm)) which may be required at the start of the movement of a vehicle according to the first speed (in revolutions per minute (or rpm), when the available electrical power is respectively insufficient (curve a1) and sufficient (curve a2).

Detailed description of the invention

The invention aims in particular to propose a control method, and an associated DC3 control device, intended to enable control of the first speed r1 of a thermal motor MMT of a hybrid powertrain (or GMP) of a vehicle V, when the latter (V) begins to move.

In the following, it is considered, by way of non-limiting example, that the vehicle V is of the automobile type. For example, it is a car, as illustrated in the . But the invention is not limited to this type of vehicle. It concerns any type of vehicle comprising a hybrid GMP transmission chain (thermal and electric). Thus, it concerns land vehicles (utility vehicles, campers, minibuses, coaches, trucks, motorcycles, road machinery, construction machinery, agricultural machinery, leisure machinery (snowmobile, kart), tracked machinery, trains and trams, for example), aircraft and boats.

We have schematically represented on the 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 power supply battery BA, and a control device DC3 according to the invention.

As illustrated, the transmission chain also comprises, here, a drive shaft AM, a first coupling device DC1, a second coupling device DC2, a gearbox BV, and a transmission shaft AT.

The operation of the transmission chain (and therefore of the GMP) is supervised by a CS supervision calculator.

The thermal engine MMT comprises a crankshaft (not shown) which is fixedly secured to the engine shaft AM in order to drive the latter (AM) in rotation. This thermal engine MMT is capable of operating according to a first speed r1, on command from the supervision computer CS. In addition, it (MMT) is capable of being coupled to a gearbox BV, having as input a second speed r2, via at least the first coupling device DC1. The latter (DC1) delivers a first torque c1 for at least one train T1 of drive wheels, when it is in its coupled position and therefore when it couples at least the thermal engine MMT to the gearbox BV.

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 the one referenced T2 which is located in the rear part PRV of the vehicle V.

Also for example, the first coupling device DC1 can be a clutch. But it could also be a torque converter or a dog clutch.

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

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 provide torque to the belt CC, which can provide this torque to the crankshaft.

It should be noted that this BA power supply battery 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.

The electric motor MME is installed between the thermal motor MMT and the first coupling device DC1, and is capable of providing a second torque c2, on the order of the supervision computer CS. At a given moment, it is the electrical power that is available in the electric motor MME that defines the second torque c2 that the latter (MME) is capable of providing to the first coupling device DC1.

When the first coupling device DC1 has been placed in its coupled state (or completely closed) and the thermal motor MMT is operating (and therefore has a first non-zero speed r1), the first coupling device DC1 delivers a first torque c1 upstream of the gearbox BV. It will be noted that this first torque c1 is a function of the first current engine speed r1 of the thermal motor and/or of the second torque c2 delivered by the electric motor MME.

It should also be noted that in the example illustrated without limitation on the the transmission chain also comprises a second DC2 coupling device installed between the thermal motor MMT and the first DC1 coupling device, in order to allow coupling of the electric motor MME between the first DC1 and second DC2 coupling devices. Thus, when the second DC2 coupling device has been placed in its decoupled (or completely open) state, only the electric motor MME can provide a second torque c2 upstream of the first DC1 coupling device and the first torque c1 delivered by the latter (DC1) is a function of this second torque c2 and therefore of the available electrical power ped of the electric motor MME.

For example, this second DC2 coupling device can be a clutch.

It should also be noted that in the example illustrated without limitation on the the first coupling device DC1, the possible second coupling device DC2, the electric motor MME and the gearbox BV are part of a gearbox assembly EBV. However, this is not an obligation.

As mentioned above, the invention proposes in particular a control method intended to allow the control of the first speed r1 of the thermal motor MMT, when the vehicle V begins to move by means of this thermal motor MMT.

This (control) method can be implemented at least partially by the control device DC3 (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 DC3 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.

The MD memory is RAM 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 performing at least one electrical or electronic operation.

In the example illustrated non-limitingly in Figures 1 and 2, the control device DC3 is part of the supervision computer CS. But this is not obligatory. Indeed, the control device DC3 could include its own dedicated computer, which is then coupled to the supervision computer CS, or could be part of another computer embedded in the vehicle V and providing at least one other function, for example.

As illustrated without limitation on the , the (control) method, according to the invention, comprises a step 10-40 which is implemented each time the movement of the vehicle V with its thermal motor MMT begins.

Step 10-40 of the method comprises a sub-step 20 in which the first regime r1 is determined (by the control device DC3) as a function of the available electrical power ped of the electric motor MME to limit the energy that is stored in the first coupling device DC1. It will be understood that this available electrical power ped is used to provide a second torque c2 that makes it possible to reduce the first regime r1 and therefore to limit the energy that is stored in the first coupling device DC1. This first regime r1 corresponds to a third torque c3.

It is recalled that the energy which is stored in the first coupling device DC1 is a function of the product of the first torque c1, which is required at the level of the latter (DC1) to start moving the vehicle V, by the difference between the first r1 and second r2 regimes.

It should be noted that this first required torque c1 is representative of the acceleration desire of the driver of vehicle V, which is for example defined by the percentage of depression of the accelerator pedal of vehicle V.

Step 10-40 of the method also includes a sub-step 30 in which the available electrical power ped of the electric motor MME is used (the control device DC3 requires the use of).

In other words, we determine the smallest first regime r1 that can be obtained in the presence of the available electrical power ped, so as to reduce the difference between the first r1 and second r2 regimes, and therefore advantageously limit the energy that is stored and consequently dissipated by the first coupling device DC1.

For example, and as illustrated without limitation on the , step 10-40 of the method may comprise a substep 10 in which one (the control device DC3) begins by determining the available electrical power ped at the instant considered. Then, one (the control device DC3) performs substep 20.

Also for example, if the available electrical power ped is considered sufficient to allow the reduction of the first regime r1, one (the control device DC3) can determine in sub-step 30 the first regime r1 as a function of this available electrical power ped and of a first torque c1 required to be provided by the first coupling device DC1.

The CS supervision calculator is then responsible for transmitting a message containing the first determined regime r1 to the calculator which controls the thermal motor MMT and another message requesting the use of the available electrical power ped to the calculator which controls the electric motor MME.

Also for example, in sub-step 30 of step 10-40, when the available electrical power ped corresponds to a second torque c2, which can be provided by the electric motor MME, which is equal to a percentage of the first required torque between 20% and 60%, one (the control device DC3) can determine a first speed r1 which is between 1300 revolutions per minute and 1800 revolutions per minute. But this range of first speeds r1 can vary from one thermal motor MMT to another, in particular according to its power. Similarly, this range of percentages can vary from one thermal motor MMT to another.

Also for example, when the available electric power ped corresponds to a second torque c2, which can be provided by the electric motor MME, which is between 20% and 60%, one (the control device DC3) can determine a first speed r1 which is equal to 1500 revolutions per minute.

Also for example, when the available electrical power ped corresponds to a second torque c2, which can be provided by the electric motor MME, which is less than 20%, in a sub-step 40 of step 10-40 on (the control device DC3) can determine a first speed r1 which is suitable for obtaining the first required torque c1 in the absence of a second torque c2. In other words, in this situation (insufficient available electrical power ped) only the thermal motor MMT is conventionally used to start moving the vehicle V, and therefore the first speed r1 is notably greater than when the available electrical power ped is sufficient. For example, instead of having a first speed r1 equal to 1500 rpm, we will have to have a first speed r1 equal to 2000 rpm.

We have schematically illustrated on the a diagram illustrating an example of the evolution of the first torque c1 (in Nm) that may be required at the start of the movement of the vehicle V as a function of the first speed r1 (in revolutions per minute (or rpm)), when the available electrical power ped is insufficient to relieve the first coupling device DC1 (curve a1) and when the available electrical power ped is sufficient to relieve the first coupling device DC1 (curve a2). The value r1 ₁ corresponds to the first speed r1 when the available electrical power ped is insufficient to relieve the first coupling device DC1, and the value r1 ₂ corresponds to the first speed r1 when the available electrical power ped is sufficient to relieve the first coupling device DC1.

As can be seen, more first torque c1 can be available when the available electrical power ped is sufficient, which allows for greater acceleration potential, while at the same time the first coupling device DC1 is no longer at risk of reaching its thermal limit beyond which it loses significant efficiency (or yield). Consequently, the invention makes it possible to reduce fuel consumption, but also to guarantee the start of movement of the vehicle V when it is towing a loaded trailer and/or when it is placed on an upward slope.

It should also be noted, as illustrated without limitation on the , that the supervision calculator CS (or the calculator of the control device DC3) can also comprise a mass memory MM1, in particular for storing each value taken by the available electrical power ped and each first required torque c1, as well as any intermediate data involved in all its calculations and processing. Furthermore, this supervision calculator CS (or the calculator of the control device DC3) can also comprise an input interface IE for receiving at least the values of the available electrical power ped and each first required torque c1, and the requests to start moving the vehicle V with the thermal engine MMT to use them in calculations or processing, possibly after having formatted 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 calculator CS (or the calculator of the control device DC3) can also include an output interface IS, in particular to deliver each message containing the first determined regime r1 and each message requiring the use of the available electrical power ped.

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 control the first speed r1 of the thermal motor MMT, when the vehicle V begins to move by means of this thermal motor MMT.

Claims (9)

Control method for a vehicle (V) comprising a powertrain comprising i) a thermal motor (MMT) capable of operating at a first speed and coupled to a gearbox (BV), having a second speed as input, via a coupling device (DC1), and ii) an electric motor (MME) installed between said thermal motor (MMT) and said coupling device (DC1) and having available electrical power, characterized in that it comprises a step (10-40) in which, when said vehicle (V) begins to move with said thermal motor (MMT), said first speed is determined as a function of said available electrical power of the electric motor (MME) to limit energy stored in said coupling device (DC1), and this available electrical power is used. Method according to claim 1, characterized in that in said step (10-40) said first regime is determined as a function of said available electrical power and a first required torque to be provided by said coupling device (DC1). Method according to claim 2, characterized in that in said step (10-40), when said available electrical power corresponds to a second torque, which can be provided by said electric motor (MME), equal to a percentage of said first required torque of between 20% and 60%, a first speed of between 1300 revolutions per minute and 1800 revolutions per minute is determined. Method according to claim 3, characterized in that in said step (10-40), when said available electrical power corresponds to a second torque, which can be provided by said electric motor (MME), equal to a percentage of said first required torque of between 20% and 60%, a first speed equal to 1500 revolutions per minute is determined. Method according to claim 3 or 4, characterized in that in said step (10-40), when said available electrical power corresponds to a second torque, which can be provided by said electric motor (MME), equal to a percentage of said first required torque less than 20%, a first regime is determined which is suitable for allowing said first required torque to be obtained in the absence of a second torque. 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 5, in a vehicle (V) comprising a powertrain comprising i) a thermal motor (MMT) capable of operating according to a first speed and coupled to a gearbox (BV), having a second speed as input, via a coupling device (DC1), and ii) an electric motor (MME) installed between said thermal motor (MMT) and said coupling device (DC1) and having available electrical power, for controlling said first speed when said vehicle (V) starts moving with said thermal motor (MMT). Control device (DC3) for a vehicle (V) comprising a powertrain comprising i) a thermal engine (MMT) capable of operating at a first speed and coupled to a gearbox (BV), having a second speed as input, via a coupling device (DC1), and ii) an electric engine (MME) installed between said thermal engine (MMT) and said coupling device (DC1) and having available electrical power, characterized in that it comprises at least one processor (PR1) and at least one memory (MD) arranged to perform the operations consisting, when said vehicle (V) starts moving with said thermal engine (MMT), in determining said first speed as a function of said available electrical power of the electric engine (MME) in order to limit an energy stored in said coupling device (DC1), and the use of this available electrical power is triggered. Vehicle (V) comprising a powertrain comprising i) a thermal motor (MMT) capable of operating at a first speed and coupled to a gearbox (BV), having a second speed as input, via a coupling device (DC1), and ii) an electric motor (MME) installed between said thermal motor (MMT) and said coupling device (DC1) and having available electrical power, characterized in that it further comprises a control device (DC3) according to claim 7. Vehicle according to claim 8, characterized in that it is of the automobile type.