GEAR CHANGE CONTROL IN A LAND VEHICLE DURING DECELERATION BY RECOVERY OF RECYCLING TORQUE

Abstract

A control method is implemented in a land vehicle and comprising a powertrain capable of recovering a regenerative braking torque to decelerate the vehicle and of supplying engine torque to a train via a gearbox having a gear engaged and chosen from several gears. This method comprises a step (10-60) in which, when a gear change is requested during the recovery of a regenerative braking torque, it is determined whether this requested gear change will cause a stoppage of the recovery of regenerative braking torque, and, if so, this gear change is prohibited. Figure 3

Description

Title of the invention: CONTROL OF GEAR CHANGES IN A LAND VEHICLE, DURING DECELERATION BY RECOVERY OF RECYCLING TORQUE Technical field of the invention

[0001] The invention relates to land vehicles comprising a powertrain capable of supplying engine torque via a gearbox and of recovering regenerative braking torque for deceleration, and more precisely the control of gear changes of the gearbox during decelerations by recovery of regenerative braking torque. State of the art

[0002] Certain land vehicles, possibly of the automobile type, comprise a powertrain (or GMP) capable of recovering a regenerative braking torque to decelerate them and of supplying engine torque to at least one of their trains via a gearbox. It will be noted that the recovery of the regenerative braking torque is carried out on command by at least one electric motor forming part of the GMP and associated with a main battery (or "power" or even "traction"). It will also be noted that the recovered regenerative braking torque is usually transformed by the electric motor into a recharging current intended to recharge the main battery, when this proves possible.

[0003] It should also be noted that the GMP can be all electric or hybrid (thermal and electric).

[0004] In a braking phase of a vehicle, and therefore when the driver presses the brake pedal (associated with the braking system), the electric motor of the GMP can provide full braking or participate in braking in combination with the braking system, or else only the braking system can provide full braking when recovery of regenerative braking torque is impossible.

[0005] When the electric motor of the GMP supplies engine torque to a train of its vehicle via a gearbox, and at the same time it provides at least partial braking (by recovery of regenerative braking torque), it happens that a gear change is requested. However, during certain gear changes it may happen that the gearbox finds itself for a brief moment in a so-called open state in which it no longer allows the recovery of torque regenerative braking. In such a situation, it is the braking system that must provide full braking (or deceleration) for the entire duration of the regenerative braking torque recovery break since the electric motor can no longer participate in braking. It often happens that the driver's braking request is not properly satisfied, which can surprise the driver and prevent good control of the vehicle (or even be potentially dangerous), and / or that there are variations in deceleration, which can also prevent good control of the vehicle and / or affect driving pleasure.

[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 land vehicle and comprising a powertrain capable of recovering a regenerative braking torque to decelerate the vehicle and of supplying engine torque to a train via a gearbox having a gear engaged and chosen from several gears.

[0008] This control method is characterized by the fact that it comprises a step in which, when a gear change is requested during the recovery of a regenerative braking torque, it is determined whether this requested gear change will cause a stoppage of the recovery of regenerative braking torque, and, if so, this gear change is prohibited.

[0009] Thanks to the invention, during a “risky” gear change the gearbox is maintained in its current state, which makes it possible to continue to correctly satisfy the driver's braking request without risk of breaking the current recovery of the regenerative braking torque.

[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, it can be determined whether a deceleration instruction, defining the recovered regenerative braking torque, is less than a maximum regenerative braking torque recoverable by the powertrain, then, if so, it can be determined whether the requested gear change will cause the recovery of regenerative braking torque to stop, and, if so, this requested gear change is prohibited;

[0012] - in its step, it can be determined whether the requested gear change will cause a stop of the recovery of regenerative braking torque in a table establishing a correspondence between torques, including different ratios, and information representative of a stop or continuity of recovery of regenerative braking torque;

[0013] - in its stage, when a change of gear has just been prohibited but the re regenerative braking torque recovery ends immediately after, this gear change can be authorized;

[0014] - in its stage, when the requested gear change is not going to cause stopping the regenerative braking torque recovery, this gear change can be authorized.

[0015] The invention also provides 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 and comprising a powertrain capable of recovering a regenerative braking torque to decelerate the vehicle and of supplying engine torque to a train via a gearbox having a gear engaged and chosen from among several gears, to control the gear changes of this gearbox.

[0016] The invention also proposes a control device intended to equip a land vehicle and comprising a powertrain capable of recovering a regenerative braking torque to decelerate the vehicle and of supplying engine torque to a train via a gearbox having a gear engaged and chosen from several gears.

[0017] 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 a gear change is requested during the recovery of a regenerative braking torque, in determining whether the requested gear change will cause a stoppage of the recovery of regenerative braking torque, and, if so, in triggering a prohibition of this gear change.

[0018] The invention also proposes a land vehicle, possibly of the automobile type, and comprising, on the one hand, a powertrain capable of recovering a regenerative braking torque to decelerate the vehicle and to supply engine torque to a train via a gearbox having a gear engaged and chosen from several gears, and, on the other hand, a control device of the type presented above.

[0019] For example, the powertrain may comprise, on the one hand, a first thermal motor capable of providing a first engine torque to the train via the gearbox, and, on the other hand, a second electric motor capable of providing a second engine torque to the train via the gearbox and of recovering the regenerative braking torque to decelerate the vehicle. Brief description of the figures

[0020] Other characteristics and advantages of the invention will appear on examining the detailed description below, and the appended drawings, in which:

[0021] [Fig.l] schematically and functionally illustrates an exemplary embodiment of a land vehicle comprising a control device according to the invention and a hybrid GMP transmission chain and associated with a supervision computer,

[0022] [Fig.2] schematically and functionally illustrates an example of the embodiment of a supervision calculator comprising an exemplary embodiment of a control device according to the invention, and

[0023] [Fig.3] schematically illustrates an example of an algorithm implementing a control method according to the invention. Detailed description of the invention

[0024] The invention aims in particular to propose a control method, and an associated control device DC3, intended to allow control of the gear changes of the gearbox BV of a land vehicle V during decelerations carried out at least in part by recovery of regenerative braking torque by at least one electric motor MM2 of the powertrain (or GMP).

[0025] 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 relates in fact to any type of land vehicle comprising a GMP transmission chain capable of providing engine torque via a gearbox to move it and of recovering a regenerative braking torque to decelerate it. Thus, it relates to utility vehicles, camper vans, minibuses, coaches, trucks, motorcycles, road machinery, construction machinery, agricultural machinery, and leisure machinery (karts), for example.

[0026] Furthermore, it is considered in the following, by way of non-limiting example, that the GMP is thermal and electric. It therefore comprises at least one first thermal motor MM1 and at least one second electric motor MM2 associated with a rechargeable battery. But the invention is not limited to this type of GMP. It also concerns all-electric GMPs and therefore comprising at least one electric motor associated with a rechargeable battery.

[0027] Furthermore, it is considered in the following, by way of non-limiting example, that the gearbox BV is automated. For example, it may be a dual clutch gearbox (or DCT (“Dual Clutch Transmission”)). But the invention is not limited to this type of gearbox, the important thing being that it comprises several ratios (at least three, and for example five, six or seven).

[0028] Finally, the transmission chain could also allow a four-wheel drive (or 4x4) or 4x2 mode.

[0029] [Fig.l] schematically shows a (land) vehicle V comprising a hybrid (thermal and electric) GMP transmission chain and BV gearbox (here automated), a supervision computer CS, a service battery BS, a rechargeable main (or traction) battery BP, a CV converter, and a DC3 control device according to the invention.

[0030] The service battery BS is responsible for supplying electrical energy to an on-board network of the vehicle V, in addition to that supplied by the CV converter powered by the main battery BP 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 or 24 V). It is rechargeable at least by the CV converter. 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] The on-board network is an electrical power supply network to which electrical (or electronic) equipment (or components) that consume electrical energy are coupled.

[0032] The main electrical circuit (or “high voltage” or “power”) is connected, on the one hand, to the main battery BP via an interface device, and, on the other hand, to electronic equipment, such as for example the CV converter and (here) the second driving machine MM2. It can also possibly allow the main battery BP to be recharged by an external power source temporarily coupled to the vehicle V.

[0033] As illustrated in [Fig.l], the transmission chain also comprises, here, a motor shaft AM, a first coupling device DC1, a second coupling device DC2, and a transmission shaft AT.

[0034] The operation of the transmission chain (and therefore of the GMP) is supervised by a CS supervision computer.

[0035] The first (thermal) driving machine MM1 comprises a crankshaft (not shown) which is fixedly secured to the engine shaft AM in order to drive the latter (AM) in rotation. This first driving machine MM1 is capable of operating according to a first speed to provide, here for a train T1 of driving wheels of the vehicle V (via the gearbox BV), a first (engine) torque which is defined by a first setpoint, for example determined by the supervision computer CS.

[0036] The operation of the first driving machine MM1 is controlled by a first machine computer CM1, and supervised by the supervision computer CS.

[0037] In addition, the first driving machine MM1 is capable of being coupled to the primary shaft AP of the gearbox BV, via at least the first coupling device DC1. The latter (DC1) is capable of delivering a torque from the first torque, in particular (here) for at least the drive wheel train Tl, when it is in its coupled position and therefore when it couples the first drive machine MM1 to the gearbox BV.

[0038] For example, the first coupling device DC1 may be a hydraulic circuit clutch. But it could be of another type.

[0039] Also 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.

[0040] 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.

[0041] The second (electric) driving machine MM2 is capable, when it is supplied with electrical energy by the main battery BP, of providing, here for the drive wheel train T1 (via the gearbox BV), a second (motor) torque which is defined by a second setpoint, for example determined by the supervision computer CS.

[0042] Furthermore, this second driving machine MM2 is suitable for being coupled, downstream of the first coupling device DC1, by the second coupling device DC2, to the primary shaft AP of the gearbox BV to provide it with the second torque that it produces (intended for the train T1).

[0043] The second (electric) prime mover MM2 is also capable of recovering a regenerative braking torque cfr (negative and defined by a negative deceleration instruction cdr) at the level of the train T1 (and therefore via the gearbox BV), to decelerate the vehicle V in a braking phase (possibly fully regenerative (or regenerative)). In this case, the recovered regenerative braking torque cfr (and therefore negative) can be used to recharge the main battery BP associated with the second prime mover MM2.

[0044] The operation of the second driving machine MM2 is controlled by a second machine computer CM2, and supervised by the supervision computer CS. In particular, the second machine computer CM2 is responsible for controlling the second driving machine MM2 so that it provides a second torque defined by the second setpoint or that it recovers a regenerative braking torque cfr defined by a deceleration setpoint cdr. The latter (cdr) can be determined by a computer of the braking system (not shown) of the vehicle V or by the computer of CS supervision or even by the second CM2 machine calculator.

[0045] 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.

[0046] Furthermore, this second coupling device DC2 may, for example, comprise a cascade of pinions connecting the output of the second driving machine MM2 to the input of the gearbox BV, and more precisely to the primary shaft AP (and therefore downstream of the first coupling device DC1).

[0047] It will be understood that when the first coupling device DC1 has been placed in its coupled (or completely closed) state and the first prime mover MM1 is in operation (and therefore has a first non-zero speed to provide the first torque), the first coupling device DC1 delivers a torque which is added to a possible second torque provided, upstream of the gearbox BV, by the second prime mover MM2 when it is supplied (here) with electrical energy (here) by the main battery BP. When the first coupling device DC1 has been placed in its uncoupled (or completely open) state, only the second prime mover MM2 can provide a second torque upstream of the gearbox BV in a purely electric driving phase.

[0048] It will be noted that the main (or "traction" or "power") battery BP may, for example, be of the cellular type. In this case, it comprises electrical energy storage cells, possibly electrochemical (such as, for example, lithium-ion (or Li-ion) or Ni-Mh or Ni-Cd type cells). Also, for example, this main battery BP may be of the 450 V type. But this is not an obligation. Indeed, it could alternatively be of the 48 V or 600 V type, for example.

[0049] As mentioned above, the invention proposes in particular a control method intended to allow the control of gear changes of the gearbox BV during decelerations carried out at least in part by recovery of regenerative braking torque by (at least) the electric motor MM2.

[0050] 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.

[0051] 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 include integrated (or printed) circuits, or several integrated (or printed) circuits connected by wired or wireless connections. An integrated (or printed) circuit is any type of device capable of performing at least one electrical or electronic operation.

[0052] In the example illustrated non-limitingly in Figures 1 and 2, the control device DC3 is part of the supervision computer CS (associated with the GMP). But this is not obligatory. Indeed, the control device DC3 could comprise its own dedicated computer, or could be part of another computer of the vehicle V, such as for example the second machine computer CM2 or the computer (not shown) controlling the gearbox BV (when it is automated).

[0053] As illustrated non-limitingly in [Fig. 3], the (control) method, according to the invention, comprises a step 10-60 which is implemented each time a gear change is requested during the recovery of a regenerative braking torque cfr (defined by a torque setpoint cdr).

[0054] Step 10-60 of the method comprises a sub-step 30 in which, when a gear change is requested during the recovery of a regenerative braking torque cfr, it is determined (for example the control device DC3) whether this requested gear change will cause a stoppage of the recovery of regenerative braking torque cfr. If so, and therefore if this will cause a stoppage (or a break in recovery), step 10-60 of the method also comprises a sub-step 40 in which this gear change is prohibited (for example the control device DC3 triggers a prohibition of).

[0055] It will be understood that the prohibition amounts to maintaining the gearbox BV in its current state, that is to say with its previously engaged ratio unchanged. Thus, the driver's braking request continues to be correctly satisfied without risk of breaking the current recovery of the regenerative braking torque cfr. This results in unchanged control of the vehicle V for the driver, without any change in driving pleasure.

[0056] For example, and as illustrated non-limitingly in [Fig. 3], step 10-60 may comprise a sub-step 10 in which one (for example the control device DC3) may begin by determining whether the deceleration setpoint cdr (defining the recovered regenerative braking torque cfr) is less than a maximum regenerative braking torque cmax which can be recovered by the powertrain at the instant in question (i.e. if cdr < cmax).

[0057] It will be understood in fact that if the deceleration instruction cdr (negative) is lower than the maximum regenerative braking torque cmax (negative) (cdr < cmax), it is therefore because its absolute value Icdrl is greater than the absolute value Icmaxl (i.e. Icdrl > Icmaxl), and therefore it (cdr) cannot be satisfied. It is then desirable to check whether the gear change should be prohibited because it is in this case that stopping the recovery will have the greatest impact since the level of regenerative braking torque recovery is the greatest (cdr strongly negative). Consequently, one (for example the control device DC3) can determine whether the requested gear change will cause the regenerative braking torque recovery cfr to stop in sub-step 30. If so, one can prohibit the (for example the control device DC3 can trigger a prohibition of the) gear change requested in sub-step 40.

[0058] On the other hand, if we have cdr > cmax (and therefore in the negative (Icdrl < Icmaxl which means that the deceleration instruction cdr can be satisfied)), we can, as illustrated non-limitatively in [Fig.3], authorize the change of gear requested in a sub-step 20 of step 10-60, without worrying about whether it will cause, or not, a stop of the recovery. Indeed, the stop of the recovery will have the least impact since the level of recovery of regenerative braking torque is the least important (cdr (very) weakly negative), and consequently this possible stop of the recovery is acceptable.

[0059] Also for example, in sub-step 30 of step 10-60, it is possible (for example the control device DC3) to determine whether the requested gear change will cause a stoppage of the recovery of regenerative braking torque cfr in a dedicated table. This table establishes a correspondence between torques, comprising different ratios of the gearbox BV, and information which is representative of a stoppage or continuity of recovery of regenerative braking torque. For example, this table can be determined in the laboratory or during the development or testing phase of a vehicle similar to the vehicle V.

[0060] Also for example, and as illustrated non-limitingly in [Fig.3], step 10-60 may comprise a sub-step 60 in which, when a gear change has just been prohibited but the recovery of regenerative braking torque cfr ends immediately after, it is possible to authorize (for example the control device DC3 can trigger an authorization of) this gear change. It will be understood in fact that if the deceleration by recovery of regenerative braking torque is going to be immediately stopped (and therefore will possibly be entirely replaced by a deceleration (or braking) by the braking system), there is no longer any reason to prohibit the requested gear change, and consequently the latter can be authorized.

[0061] Also for example, and as illustrated non-limitingly in [Fig.3], step 10-60 may comprise a sub-step 50 in which, when it is noted in sub-step 30 that the requested gear change will not cause the regenerative braking torque recovery cfr, we can authorize (for example the DC3 control device can trigger an authorization of) this gear change. We will understand in fact that in this situation we have no reason to prohibit the gear change.

[0062] It will also be noted, as illustrated non-limitingly in [Fig. 2], that the supervision computer CS (or the computer of the control device DC3) can also comprise a mass memory MEM, in particular for storing each deceleration instruction cdr and each possible maximum regenerative braking torque cmax, as well as any intermediate data involved in all its calculations and processing operations. Furthermore, this supervision computer CS (or the computer of the control device DC3) can also comprise an input interface IE for receiving at least each deceleration instruction cdr and each possible maximum regenerative braking torque cmax, to use them in calculations or processing operations, 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 DC3 control device calculator) can also include an IS output interface, in particular to deliver a message containing a gear change prohibition or authorization.

[0063] 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 gear changes of the gearbox BV of the vehicle V during decelerations carried out at least in part by recovery of regenerative braking torque by (at least) the electric motor MM2.

Claims

Claims

1. Control method for a land vehicle (V) and comprising a powertrain capable of recovering a regenerative braking torque to decelerate said vehicle (V) and of supplying engine torque to a train via a gearbox (BV) having a gear engaged and chosen from several gears, characterized in that it comprises a step (10-60) in which, when a gear change is requested during the recovery of a regenerative braking torque, it is determined whether said requested gear change will cause a stop of said recovery of regenerative braking torque, and, if so, this gear change is prohibited.

2. Method according to claim 1, characterized in that in said step (10-60) it is determined whether a deceleration setpoint, defining said recovered regenerative braking torque, is less than a maximum regenerative braking torque recoverable by said powertrain, then, if so, it is determined whether said requested gear change will cause said stopping of the recovery of regenerative braking torque, and, if so, said requested gear change is prohibited.

3. Method according to claim 1 or 2, characterized in that in said step (10-60) it is determined whether said requested gear change will cause a stop of said regenerative braking torque recovery in a table establishing a correspondence between torques comprising different gears and information representative of a stop or continuity of regenerative braking torque recovery.

4. Method according to one of claims 1 to 3, characterized in that in said step (10-60), when a gear change has just been prohibited but said regenerative braking torque recovery ends immediately afterwards, this gear change is authorized.

5. Method according to one of claims 1 to 3, characterized in that in said step (10-60), when said requested gear change will not cause said regenerative braking torque recovery to stop, this gear change is authorized.

6. 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 land vehicle (V) and comprising a powertrain capable of recovering a regenerative braking torque to decelerate said vehicle (V) and of supplying engine torque to a train via a gearbox (BV) having a gear engaged and chosen from several gears, to control the gear changes of said gearbox (BV).

7. Control device (DC3) for a land vehicle (V) and comprising a powertrain capable of recovering a regenerative braking torque to decelerate said vehicle (V) and of supplying engine torque to a train via a gearbox (BV) having a gear engaged and chosen from several gears, characterized in that it comprises at least one processor (PR1) and at least one memory (MD) arranged to carry out the operations consisting, when a gear change is requested during the recovery of a regenerative braking torque, in determining whether said requested gear change will cause a stoppage of said recovery of regenerative braking torque, and, if so, in triggering a prohibition of this gear change.

8. Land vehicle (V) comprising a powertrain capable of recovering a regenerative braking torque to decelerate said vehicle (V) and of supplying engine torque to a train via a gearbox (BV) having a gear engaged and chosen from several gears, characterized in that it further comprises a control device (DC3) according to claim 7.

9. Vehicle according to claim 8, characterized in that said powertrain comprises i) a first thermal motor (MM1) capable of supplying a first engine torque to said train via said gearbox (BV), and ii) a second electric motor (MM2) capable of supplying a second engine torque to said train via said gearbox (BV) and of recovering said regenerative braking torque to decelerate said vehicle (V).

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

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