CONTROL OF THE START OF MOTION OF A LAND VEHICLE WITH A HYBRID POWERTRAIN

Abstract

A control method is implemented in a land vehicle comprising a powertrain with a first internal combustion engine that can be coupled by a first coupling device to a gearbox to provide it with a first motor torque, and a second electric motor that can be coupled, downstream of the first coupling device by a second coupling device, to the gearbox to provide it with a second motor torque. This control method includes a step (10-20) in which, when the brake pedal is pressed and the vehicle is required to begin moving by supplying a first motor torque, the second motor is instructed to supply a second motor torque chosen to stress the second coupling device. Figure 3

Description

Title of the invention: CONTROLLING THE START OF MOVEMENT OF A GMP LAND VEHICLE HYBRID Technical field of the invention

[0001] The invention relates to land vehicles comprising a hybrid powertrain, and more specifically to the control of the start of movement (or take-off) of such vehicles. State of the art

[0002] Certain land vehicles, possibly of the automobile type, include a hybrid powertrain (or GMP), i.e. comprising a thermal motor and an electric motor.

[0003] Here, the term “drive machine” means a thermal engine or an electric machine arranged to provide engine torque to move a vehicle.

[0004] Certain hybrid GMPs of the aforementioned vehicles comprise, on the one hand, a first thermal motor machine and suitable for being coupled by a first coupling device to a gearbox to provide it with a first engine torque, and, on the other hand, a second electric motor machine and suitable for being coupled, downstream of the first coupling device by a second coupling device, to the gearbox to provide it with a second engine torque.

[0005] Generally, the second coupling device comprises a cascade of pinions connecting the second (electric) driving machine to the input of the gearbox. As a result, at the start of a movement (or take-off) of a vehicle by supplying a first engine torque by the first (thermal) driving machine, the acyclisms of the latter induce audible shot noise at the teeth of the cascade of pinions.

[0006] It is recalled that the shot noise is due to the chattering of the idler gears of the cascade in the presence of acyclic excitation at the input of the gearbox. This results from the fact that when the second driving machine is not active the gears of the cascade are free to move, and therefore idle, so that they collide at the level of their inter-tooth clearances.

[0007] This shot noise being very metallic, it is often anxiety-inducing when it is audible (which is the case during takeoff). However, the greater the acyclic excitation, the greater the level of shot noise. In addition, the greater the inertia of the rotor of the second (electric) prime mover, the greater the shot noise.

[0008] If one wishes to reduce shot noise, one can reduce the influence of acyclisms. To do this, one can install a third coupling device acting as a filter between the output of the first (thermal) prime mover and the input of the first coupling device (generally a clutch). However, the more significant acyclism the first (thermal) prime mover generates, the more inertia (and therefore mass) must be placed on the third coupling device, which increases the weight of the vehicle and therefore its driving energy consumption, but also the manufacturing and operating costs of the vehicle. Furthermore, there is currently no known third coupling device capable of reducing acyclic excitations sufficiently so that shot noise is almost inaudible in a vehicle cabin during takeoff.

[0009] It is also possible to use a device for compensating for inter-tooth clearances in the cascade of pinions. But such a device proves to be expensive and relatively bulky, and it proves very difficult to guarantee its durability.

[0010] The invention therefore aims in particular to improve the situation. Presentation of the invention

[0011] It proposes in particular for this purpose a control method intended to be implemented in a land vehicle comprising brake and accelerator pedals and a powertrain (or GMP) comprising, on the one hand, a first thermal motor machine and suitable for being coupled by a first coupling device to a gearbox to provide it with a first engine torque, and, on the other hand, a second electric motor machine and suitable for being coupled, downstream of the first coupling device by a second coupling device, to the gearbox to provide it with a second engine torque.

[0012] This control method is characterized by the fact that it comprises a step in which, when the brake pedal is pressed and a start of movement of the vehicle by supplying a first engine torque is required, the second prime mover is ordered to supply a second engine torque chosen to stress the second coupling device.

[0013] Thus, the second coupling device does not induce shot noise when the vehicle takes off.

[0014] The control method according to the invention may include other characteristics which may be taken separately or in combination, and in particular:

[0015] - in its step, we can order the supply of the second chosen motor torque when a percentage of brake pedal depression is greater than or equal to a chosen threshold;

[0016] - in the presence of the first option, in its step, the chosen threshold can be understood between 5% and 15%;

[0017] - in a first embodiment, in its step it is possible to order the second prime mover to provide the second selected motor torque until the first prime mover actually provides a first motor torque of a selected value;

[0018] - in the presence of the last option, in its step, the value can be chosen in function of a percentage of depression of the accelerator pedal after the end of depression of the brake pedal;

[0019] - in a second embodiment, in its step, it is possible to order the second prime mover to provide the second chosen engine torque for a predefined duration;

[0020] - in its step the second chosen engine torque can be between 2 Nm and 5 Nm

[0021] 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 land vehicle comprising brake and accelerator pedals and a powertrain (or GMP) comprising, on the one hand, a first thermal motor machine and capable of being coupled by a first coupling device to a gearbox to provide it with a first engine torque, and, on the other hand, a second electric motor machine and capable of being coupled, downstream of the first coupling device by a second coupling device, to the gearbox to provide it with a second engine torque, to control each start of movement of the vehicle.

[0022] The invention also proposes a control device intended to equip a land vehicle comprising brake and accelerator pedals and a powertrain (or GMP) comprising, on the one hand, a first thermal motor machine and suitable for being coupled by a first coupling device to a gearbox to provide it with a first engine torque, and, on the other hand, a second electric motor machine and suitable for being coupled, downstream of the first coupling device by a second coupling device, to the gearbox to provide it with a second engine torque.

[0023] 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 brake pedal is pressed and a start of movement of the vehicle by supplying a first engine torque is required, in requiring that the second prime mover supply a second engine torque chosen to stress the second coupling device.

[0024] The invention also provides a land vehicle, possibly of the type automobile, and comprising, on the one hand, brake and accelerator pedals and a powertrain (or GMP) comprising a first thermal motor and suitable for being coupled by a first coupling device to a gearbox to provide it with a first engine torque, and a second electric motor and suitable for being coupled, downstream of the first coupling device by a second coupling device, to the gearbox to provide it with a second engine torque, and, on the other hand, a control device of the type presented above. Brief description of the figures

[0025] Other characteristics and advantages of the invention will appear on examining the detailed description below, and the appended drawings, in which:

[0026] [Fig-1] schematically and functionally illustrates an example of the embodiment of a land vehicle comprising a hybrid GMP transmission chain and supervised by a supervision computer, and a control device according to the invention,

[0027] [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, and

[0028] [Fig.3] schematically illustrates an example of an algorithm implementing a control method according to the invention. Detailed description of the invention

[0029] The invention aims in particular to propose a control method, and an associated DC control device, intended to enable control of the start of movement (or take-offs) of a land vehicle V with a hybrid powertrain (or GMP) in order to limit shot noise as much as possible.

[0030] In the following, it is considered, by way of non-limiting example, that the land 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 land vehicle. It in fact concerns any type of land vehicle comprising a hybrid GMP transmission chain. Thus, it concerns utility vehicles, camper vans, minibuses, coaches, trucks, motorcycles, road machinery, construction machinery, agricultural machinery, and leisure machinery (karts), for example.

[0031] [Fig.l] schematically shows a (land) vehicle V comprising a hybrid GMP transmission chain (and therefore comprising a first thermal motor MM1 and a second electric motor MM2), a supervision computer CS, a service battery BS, a rechargeable battery BR, a converter CV, and a DC control device according to the invention.

[0032] The service battery BS is responsible for supplying electrical energy to the on-board network of the vehicle V, in addition to that supplied by the CV converter supplied by the rechargeable battery BR via a main electrical circuit, and sometimes instead 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 CV converter. In the following, as a non-limiting example, it is considered that the service battery BS is of the 12 V Lithium-ion type.

[0033] The on-board network is an electrical power supply network to which electrical (or electronic) equipment (or components) that consume electrical energy are coupled.

[0034] The main electrical circuit (or “high voltage” or “power”) is connected, on the one hand, to the rechargeable battery BR via an interface device, and, on the other hand, to electronic equipment, such as for example the CV converter and the first MM1 and second MM2 driving machines. It also allows the rechargeable battery BR to be recharged by an external power source and temporarily coupled to a charging connector of the vehicle V.

[0035] The transmission chain has a GMP which is hybrid and therefore which comprises, in addition to its first MM1 and second MM2 driving machines, in particular, a motor shaft AM, a transmission shaft AT, first DC1 and second DC2 coupling devices, and a gearbox BV.

[0036] It is recalled that here the term “drive machine” means a machine arranged so as to provide engine torque to move the vehicle V.

[0037] The operation of the transmission chain (and therefore of the GMP) is supervised by a CS supervision computer.

[0038] The first driving machine MM1 is thermal and is responsible, when supplied with fuel, for producing a first torque cl and supplying the latter (cl) to the motor shaft AM.

[0039] Furthermore, this first driving machine MM1 (and more precisely the motor shaft AM) is capable of being coupled by the first coupling device DC1 to the primary shaft AP of the gearbox BV to provide it with the first motor torque c 1 produced.

[0040] The output shaft of the gearbox BV is coupled to the transmission shaft AT which is itself coupled to a first train T1 (here of wheels), preferably via a differential DI.

[0041] This first train T1 is here located in the front part PVV of the vehicle V. But in a variant this first train T1 could be the one which is here referenced T2 and which is located in the rear part PRV of the vehicle V.

[0042] For example, the first coupling device DC1 may be a hydraulic circuit clutch. But it could be of another type.

[0043] Also, for example, the gearbox BV can be automated. Thus, it can, for example, be a double clutch (or DCT (“Dual Clutch Transmission”)). But this is not obligatory.

[0044] It will be noted that in the example illustrated non-limitingly in [Fig.l] the crankshaft of the first prime mover MM1 is also coupled to a belt, itself coupled to an alternator-starter AD which is supplied with electrical energy by the service battery BS (and which can also recharge the latter (BS)). Thus, the alternator-starter AD can supply torque to the belt, which can supply this torque to the crankshaft.

[0045] It will also be noted that in the example illustrated non-limitingly in [Fig.l] the GMP also comprises a third coupling device DC3 acting as a filter between the motor shaft AM and the input of the first coupling device DC1. This third coupling device DC3 is arranged so as to reduce the acyclisms produced by the first driving machine MME But it is not obligatory.

[0046] For example, this third coupling device DC3 can be a double pendulum damping flywheel.

[0047] The second driving machine MM2 is electric and is responsible, when supplied with electrical energy by the rechargeable battery BR, for producing a second torque c2.

[0048] Furthermore, this second driving machine MM2 is capable of being coupled, downstream of the first coupling device DC1, by the second coupling device DC2, to the gearbox BV to provide it with the second engine torque c2 produced.

[0049] The operation of the second electric motor MM2 is controlled by a machine computer (not shown), and supervised by the supervision computer CS.

[0050] The second coupling device DC2 can be placed in coupled and decoupled states, depending on a state instruction generated by the GMP supervision computer CS.

[0051] Furthermore, this second coupling device DC2 comprises a cascade of pinions connecting the second driving machine MM2 to the input of the gearbox BV (downstream of the first coupling device DC1).

[0052] The CV converter is also responsible, here, during the driving phases of the vehicle V for converting part of the electric current stored in the rechargeable battery BR to supply converted electric current to the on-board network and the service battery BS (to recharge it).

[0053] The rechargeable battery BR 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 rechargeable battery BR may be of the low voltage type (typically 450 V for illustration purposes). But it could be medium voltage or high voltage type.

[0054] The vehicle V also comprises a brake pedal PF having a first depression percentage pel variable by action of the driver, and an accelerator pedal PA having a second depression percentage pe2 variable by action of the driver.

[0055] As mentioned above, the invention proposes in particular a control method intended to enable the control of the start of movement (or take-offs) of the (land) vehicle V in order to limit shot noise as much as possible.

[0056] This (control) method can be implemented at least partially by the DC control device (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 control device 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.

[0057] The memory MD 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 carrying out at least one electrical or electronic operation.

[0058] In the example illustrated non-limitingly in Figures 1 and 2, the control device DC is part of the supervision computer CS. But this is not obligatory. Indeed, the control device DC could comprise its own dedicated computer, which is then coupled to the supervision computer CS, for example.

[0059] As illustrated non-limitingly in [Fig. 3], the (control) method, according to the invention, comprises a step 10-20 which is implemented each time two conditions are satisfied, namely the brake pedal PF is pressed and a start of movement (or take-off) of the vehicle V, by supplying a first engine torque cl, is required. It will be noted that the request results from the selection by the driver of the vehicle V of first gear or reverse with the gear lever associated with the gearbox BV (when it is manual) or from the selection of the forward or reverse position with the gear lever associated with the gearbox BV (when it is automated). Each time such a request is present, information representing it is transmitted to the supervision computer CS, which then transmits it to the control device DC.

[0060] Step 10-20 of the method comprises a sub-step 20 in which, when the two conditions are satisfied, the second driving machine MM2 is ordered to provide a second chosen motor torque c2' to constrain the second DC2 coupling device.

[0061] For example, it is the DC control device which may require that the second prime mover MM2 provides the second chosen motor torque c2' to stress the second coupling device DC2. In this case, the DC control device may, for example, generate a request, requiring the provision of the second chosen motor torque c2', intended for the supervision computer CS, and, upon receipt of this request, the supervision computer CS sends the machine computer a torque instruction intended to allow the provision of the second chosen motor torque c2' by the second prime mover MM2.

[0062] Thanks to this stressing of the second coupling device DC2 (and more precisely of the pinions of its cascade) by the reception of the second chosen motor torque c2', the teeth of the pinions of the cascade are brought into contact and therefore do not induce shot noise.

[0063] It will be noted that the second chosen engine torque c2' must be sufficient for the teeth to come into contact when the vehicle V takes off, without being too great because this could generate a shock when the transmission chain is torqued and without this causing significant consumption of the electrical energy stored in the rechargeable battery BR.

[0064] For example, in sub-step 20 of step 10-20 the second chosen engine torque c2' can be between 2 Nm and 5 Nm. As an illustrative example, the second chosen engine torque c2' can be equal to 3 Nm. But other values ​​of second chosen engine torque c2' can be used. For example, the value of the second chosen engine torque c2' can be determined during the development phase of the vehicle V.

[0065] Also for example, in sub-step 20 of step 10-20 it is possible to order (for example the DC control device may require) the supply of the second chosen motor torque c2' when the first percentage of depression pel of the brake pedal PF is greater than or equal to a threshold si chosen (i.e. pel > si).

[0066] It will be noted that the threshold si is chosen so that the resistive torque of the braking system of the vehicle V is much stronger than the second chosen torque c2' provided by the second driving machine MM2 (including gear reduction). Consequently, the threshold si must not be too low because there would be a risk that the second chosen torque c2' causes an unwanted movement of the vehicle V at least on a slope.

[0067] For example, in sub-step 10 of step 10-20 the threshold si can be between 5% and 15%. As an illustrative example, the threshold si can be equal to 10%. But other threshold si values ​​can be used. For example, the threshold si value can be determined during the development phase of the vehicle V.

[0068] In this case, as illustrated non-limitingly in [Fig.3], step 10-20 can include a sub-step 10 in which one (for example the control device DC) can compare the first percentage of pel depression to the threshold si. If the result of this comparison indicates that the first percentage of pel depression is lower than the first threshold si, it is considered that there would be a risk of movement of the vehicle V, and therefore sub-step 10 will be carried out again when the next first percentage of pel depression is available.

[0069] On the other hand, if the result of the comparison indicates that the first percentage of sinking pel is greater than or equal to the first threshold si, sub-step 20 is carried out.

[0070] At least two embodiments of the method can be envisaged.

[0071] In a first embodiment, in sub-step 20 of step 10-20 it is possible order the second prime mover MM2 to provide the second chosen engine torque c2' until the first prime mover MM1 actually provides a first engine torque cl of a chosen value vc. In other words, as long as the first prime mover MM1 does not provide a first engine torque cl equal to the chosen value vc, the second prime mover MM2 continues to be ordered to provide the second chosen engine torque c2'. On the other hand, as soon as the first engine torque cl becomes equal to the chosen value vc, the second prime mover MM2 is no longer ordered to provide the second chosen engine torque c2', because it is considered that the takeoff phase is over and therefore that there is no longer any risk that the shot noise will be audible to the passengers of the vehicle V.

[0072] It will be noted that in sub-step 20 of step 10-20 the value vc can be chosen as a function of the second percentage of depression pe2 of the accelerator pedal PA, after the end of depression of the brake pedal PF. It will be understood in fact that according to this second percentage of depression pe2, the torque desired at take-off by the driver can be more or less significant, and therefore the value vc to be achieved, and which is representative of the end of the take-off phase, can be more or less significant.

[0073] But in a variant the chosen value vc could be predefined (and therefore fixed).

[0074] In a second embodiment, in sub-step 20 of step 10-20 it is possible order the second prime mover MM2 to provide the second chosen motor torque c2' for a predefined duration dp.

[0075] For example, in sub-step 20 of step 10-20 the predefined duration dp may be between 0.5 s and 1.5 s. As an illustrative example, the predefined duration dp may be equal to 1 s. But other values ​​of predefined duration dp may be used. For example, the value of the predefined duration dp may be chosen during the development phase of the vehicle V.

[0076] It will also be noted, as illustrated non-limitingly in [Fig.2], that the supervision computer CS (or the computer of the control device DC) can also include a mass memory MEM, in particular for storing each possible first percentage of sinking pel and each possible second percentage of sinking pe2, 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 DC) can also include an input interface IE for receiving at least the information representative of a take-off request, each possible first percentage of sinking pel and each possible second percentage of sinking pe2, 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 CS supervision calculator (or the DC control device calculator) can also include an IS output interface, in particular to deliver a message (or order) to supply the second chosen motor torque c2'.

[0077] 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 each start of movement (or takeoff) of the land vehicle V.

Claims

Claims

1. Control method for a land vehicle (V) comprising brake (PF) and accelerator (PA) pedals and a powertrain comprising i) a first thermal prime mover (MM1) capable of being coupled by a first coupling device (DC1) to a gearbox (BV) to provide it with a first engine torque, and ii) a second electric prime mover (MM2) capable of being coupled, downstream of said first coupling device (DC1) by a second coupling device (DC2), to said gearbox (BV) to provide it with a second engine torque, characterized in that it comprises a step (10-20) in which, when said brake pedal (PF) is pressed and a start of movement of said vehicle (V) by supplying a first engine torque is required, said second prime mover (MM2) is ordered to supply a second engine torque chosen to stress said second coupling device (DC2).

2. Method according to claim 1, characterized in that in said step (10-20) the supply of said second chosen engine torque is ordered when a percentage of depression of said brake pedal (PF) is greater than or equal to a chosen threshold.

3. Method according to claim 2, characterized in that in said step (10-20) said chosen threshold is between 5% and 15%.

4. Method according to one of claims 1 to 3, characterized in that in said step (10-20) said second driving machine (MM2) is ordered to provide said second chosen driving torque until said first driving machine (MM1) actually provides a first driving torque of a chosen value.

5. Method according to claim 4, characterized in that in said step (10-20) said value is chosen as a function of a percentage of depression of said accelerator pedal (PA) after the end of depression of said brake pedal (PF).

6. Method according to one of claims 1 to 3, characterized in that in said step (10-20) said second driving machine (MM2) is ordered to provide said second chosen motor torque for a predefined duration.

7. Method according to one of claims 1 to 6, characterized in that in said step (10-20) said second chosen engine torque is between 2 Nm and 5 Nm

8. 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 7, in a land vehicle (V) comprising brake (PF) and accelerator (PA) pedals and a powertrain comprising i) a first thermal prime mover (MM1) capable of being coupled by a first coupling device (DC1) to a gearbox (BV) to provide it with a first engine torque, and ii) a second electric prime mover (MM2) capable of being coupled, downstream of said first coupling device (DC1) by a second coupling device (DC2), to said gearbox (BV) to provide it with a second engine torque, to control each start of movement of said vehicle (V).

9. Control device (DC) for a land vehicle (V) comprising brake (PF) and accelerator (PA) pedals and a powertrain comprising i) a first thermal prime mover (MM1) suitable for being coupled by a first coupling device (DC1) to a gearbox (BV) to provide it with a first engine torque, and ii) a second electric prime mover (MM2) suitable for being coupled, downstream of said first coupling device (DC1) by a second coupling device (DC2), to said gearbox (BV) to provide it with a second engine torque, characterized in that it comprises at least one processor (PR1) and at least one memory (MD) arranged to carry out the operations consisting, when said brake pedal (PF) is pressed and a start of movement of said vehicle (V) by providing a first engine torque is required,to require that said second driving machine (MM2) provides a second motor torque chosen to stress said second coupling device (DC2).,

10. Land vehicle (V) comprising brake (PF) and accelerator (PA) pedals and a powertrain comprising i) a first thermal prime mover (MM1) capable of being coupled by a first coupling device (DC1) to a gearbox (BV) to provide it with a first engine torque, and ii) a second electric prime mover (MM2) capable of being coupled, downstream of said first coupling device (DC1) by a second coupling device (DC2), to said gearbox (BV) to provide it with a second motor torque, characterized in that it further comprises a control device (DC) according to claim 9.

Images