Control of regenerative braking modes in a land vehicle with a speed control function

Abstract

A control method is implemented in a land vehicle including a speed control function controlling the current speed of the vehicle as a function of a speed setpoint, and a powertrain providing first and second selectable regenerative braking modes and making it possible to recover regenerative braking torques having first and second levels, respectively, the first level being lower than the second level. This method comprises a step (10-50) in which, when the first regenerative braking mode is selected, and when a target acceleration required by the speed control function is lower than a potential minimum acceleration that can be provided by the powertrain in the first regenerative braking mode, the use of the second regenerative braking mode is imposed in order to comply with the speed setpoint.

Description

DESCRIPTION TITLE: CONTROL OF RECOVERY BRAKE MODES IN A LAND VEHICLE WITH SPEED CONTROL FUNCTION The present invention claims priority from French application No. 2303451 filed on 06.04.2023, the content of which (text, drawings and claims) is incorporated herein by reference. Technical field of the invention

[0001] The invention relates to land vehicles comprising a powertrain (or PMT) capable of recovering regenerative braking torque and at least one speed control function capable of controlling their speed, and more specifically the control of regenerative braking modes in such vehicles. State of the art

[0002] Some land vehicles, possibly of the automobile type, include:

[0003] - a powertrain (or powertrain) designed to supply drive wheels with a torque that is a function of a torque setpoint and greater than or equal to a first minimum torque,

[0004] - an accelerator pedal having a percentage of depressment from which the torque setpoint is defined, the latter being greater than or equal to a second minimum torque which is strictly greater than the first minimum torque, and

[0005] - a dedicated speed control function, when activated, to generate the torque setpoint as a function of a speed setpoint to control the current speed.

[0006] As anyone skilled in the art knows, current speed control functions do not intervene in a vehicle's braking strategies. The only means these functions have at their disposal to decelerating the vehicle when necessary means generating negative torque commands to recover regenerative braking torque to maintain their speed command.

[0007] One drawback is that currently, the maximum regenerative braking torque that a speed control function can recover is equal to the second minimum torque, which corresponds to a zero (0%) accelerator pedal depressment and is strictly greater than the first minimum torque for reasons of driving comfort and safety. Consequently, the level of deceleration that can be achieved is relatively low, and therefore the time required to maintain the set speed is relatively long.

[0008] It should be noted that the level of deceleration is very low when the vehicle's driver has selected the first regenerative braking mode from among the first and second regenerative braking modes. These modes allow for the recovery of regenerative braking torques with first and second levels respectively, the first level being lower than the second level (these are absolute values). Indeed, when this first regenerative braking mode is selected, the low level of deceleration achievable through the recovery of a low regenerative braking torque (first level) forces the speed control function to frequently resort to the vehicle's braking system on descents.Consequently, a good portion of the braking energy is dissipated in the brakes as a pure waste, even though it could have been at least partially used to recharge the vehicle's rechargeable battery and thus increase the vehicle's mileage range.

[0009] The invention is therefore intended, in particular, to improve the situation. Presentation of the invention

[0010] In particular, it proposes a control method for this purpose, intended to be implemented in a land vehicle and comprising:

[0011] - an accelerator pedal,

[0012] - a dedicated speed control function, which, when activated, controls the vehicle's current speed according to a set speed, and

[0013] - a powertrain designed to ensure selectable first and second modes of regenerative braking and enabling the recovery in the vehicle of regenerative braking torques having respectively first and second levels, the first level being lower than the second level.

[0014] This control method is characterized by the fact that it includes a step in which, when the first regenerative braking mode is selected, and when a target acceleration required by the speed control function is less than a potential minimum acceleration that can be ensured by the powertrain in the first regenerative braking mode, the use of the second regenerative braking mode is enforced to maintain the speed setpoint.

[0015] Thanks to the invention, it is now possible to recover more regenerative braking torque, and therefore decelerate (or brake) the vehicle more strongly, while using the vehicle's braking system less often, which makes it possible to meet the speed setpoint more quickly and to convert a greater amount of regenerative braking torque into electrical energy to recharge the rechargeable battery.

[0016] The control method according to the invention may include other features which may be taken separately or in combination, and in particular:

[0017] - in its step, once the second regenerative braking mode is imposed, it can be determined whether another target acceleration, defined according to a percentage of accelerator pedal depressment, is less than the potential minimum acceleration, and if so, the imposition of the second regenerative braking mode can be maintained;

[0018] - in the presence of the first option, in its stage, when the other target acceleration is greater than the potential minimum acceleration, the second regenerative braking mode can cease to be imposed.

[0019] The invention also proposes a computer program product comprising a set of instructions which, when executed by processing means, is suitable for implementing a control method of the type presented above, in a land vehicle and comprising, firstly, an accelerator pedal, secondly, a speed control function which, when activated, controls a current speed of the vehicle according to a speed setpoint, and, thirdly, a powertrain suitable for ensuring selectable first and second regenerative braking modes and allowing the recovery in the vehicle of regenerative braking torques having respectively first and second levels, the first level being lower than the second level, to control the use of the first and second regenerative braking modes.

[0020] The invention also proposes a control device intended to equip a land vehicle and comprising:

[0021] - an accelerator pedal,

[0022] - a dedicated speed control function, which, when activated, controls the vehicle's current speed according to a set speed, and

[0023] - a powertrain designed to provide selectable first and second regenerative braking modes and to recover in the vehicle regenerative braking torques having respectively first and second levels, the first level being lower than the second level.

[0024] This control device is characterized by the fact that it includes at least one processor and at least one memory arranged to perform the operations consisting, when the first regenerative braking mode is selected, and when a target acceleration required by the speed control function is less than a potential minimum acceleration that can be ensured by the powertrain in the first regenerative braking mode, of triggering an imposition of the use of the second regenerative braking mode to comply with the speed setpoint.

[0025] The invention also proposes a land vehicle, possibly of the automobile type, comprising:

[0026] - an accelerator pedal,

[0027] - a dedicated speed control function, which, when activated, controls the vehicle's current speed according to a set speed.

[0028] - a powertrain designed to provide selectable first and second regenerative braking modes, enabling the recovery of regenerative braking torques within the vehicle, with first and second levels respectively, the first level being lower than the second level, and

[0029] - a control device of the type described above.

[0030] For example, this vehicle may include a rechargeable battery designed to store electrical energy, and the powertrain may include at least one electric drive unit designed to recover regenerative braking torque and convert this recovered regenerative braking torque into electrical energy to recharge the rechargeable battery. Brief description of the figures

[0031] Other features and advantages of the invention will become apparent upon examination of the detailed description below, and the accompanying drawings, in which:

[0032] [Fig. 1] schematically and functionally illustrates an example of an embodiment of a land vehicle comprising a control device according to the invention, a speed control computer, and a hybrid powertrain and supervisory computer.

[0033] [Fig. 2] schematically and functionally illustrates an example of an embodiment of a supervisory computer comprising an example of an embodiment of a control device according to the invention,

[0034] [Fig. 3] schematically illustrates an example of an algorithm implementing a control method according to the invention. Detailed description of the invention

[0035] The invention aims in particular to propose a control method, and an associated DC3 control device, intended to allow control of the use of the first m1 and second m2 regenerative braking modes of a land vehicle V with FCV speed control function.

[0036] In what follows, we consider, by way of non-limiting example, that the land vehicle V is of the automobile type. This is, for example, a car, as illustrated in Figure 1. However, the invention is not limited to this type of land vehicle. It relates in fact to any type of land vehicle comprising a powertrain (or PWM) including at least one electric motor, a speed control function, and selectable first and second regenerative braking modes allowing the recovery of regenerative braking torques having first and second levels respectively, the first level being lower than the second level (we are referring here to absolute values).

[0037] Figure 1 schematically represents a (land) vehicle V comprising a hybrid GMP transmission chain (and therefore in particular a thermal drive machine MMT and an electric drive machine MME), a CS supervisory computer, a rechargeable battery BR, an accelerator pedal PA, a speed control computer CA, and a DC3 control device according to the invention.

[0038] It should be noted that the powertrain could also be fully electric. Furthermore, the drivetrain could also allow for four-wheel drive (or 4x4) or 4x2 operation.

[0039] As illustrated, the transmission chain also includes, here, a drive shaft AM, a first coupling device DC1, a second coupling device DC2, a gearbox BV, and a transmission shaft AT.

[0040] The operation of the transmission chain (and therefore the powertrain) is supervised by a CS supervisory computer.

[0041] The MMT (thermal power unit) includes a crankshaft (not shown) which is fixedly attached to the drive shaft AM to rotate the latter (AM). This MMT is designed to be coupled to the gearbox BV via the first coupling device DC1, as well as, in this case, via the second coupling device DC2 (optional). Furthermore, it (MMT) is designed to be coupled to the input shaft AP of the gearbox BV via the first coupling device DC1, as well as, in this case, via the second coupling device DC2 (optional). This coupling device DC1 is designed to deliver a second torque c2 from the first torque c1 produced by the MMT, for the gearbox BV. Finally, this gearbox BV is designed to deliver a third torque c3 from the second torque c2 delivered by the coupling device DC1, for at least one set T1 of drive wheels.This third couple c3 is defined by a torque setpoint ccg which is transmitted by the CS supervisory computer.

[0042] For example, the T1 axle can be located in the front PW section of vehicle V. It is preferably, as illustrated, coupled to the AT driveshaft via a differential (here, the front one) DV. However, in a variant, this T1 axle could be the one referenced as T2, which is located in the rear PRV section of vehicle V.

[0043] For example, the first DC1 coupling device could be a clutch (single or double). But it could also be a torque converter or a dog clutch.

[0044] 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. It should be noted that it is preferable for the gearbox (BV) to be automated.

[0045] In the example illustrated (which is not exhaustive), the crankshaft of the MMT internal combustion engine is also coupled to a DC belt, itself coupled to an AD alternator-starter which is supplied with energy The electrical system is powered by the rechargeable battery BR (which can also recharge the battery (BR)). Thus, the alternator-starter AD can supply torque to the belt CC, which in turn supplies this torque to the crankshaft.

[0046] Note that this BR rechargeable battery can, for example, be of the 48V type. However, this is not mandatory. Indeed, it could alternatively be of the 12V, 24V, or 400V type, for example.

[0047] The electric drive unit (MME) is installed (here) between the internal combustion engine unit (MMT) and the first coupling device DC1, and is designed to provide torque on command from the supervisory computer CS when it is powered by the rechargeable battery BR. It (MME) is also designed to recover regenerative braking torque, defined by a (negative) regenerative braking torque setpoint, to brake the vehicle V, and to convert this recovered regenerative braking torque into electrical energy to recharge the rechargeable battery BR.

[0048] When the first coupling device DC1 has been placed in its fully coupled (or completely closed) state and the thermal drive machine MMT supplies (positive) torque and / or the electric drive machine MME supplies (positive) torque, the first coupling device DC1 delivers torque to the primary shaft AP of the gearbox BV.

[0049] It should also be noted that in the example illustrated (though not exhaustively) in Figure 1, the transmission chain includes a second coupling device DC2 installed between the internal combustion engine MMT and the first coupling device DC1, in order to allow coupling of the electric motor MME between the first DC1 and second DC2 coupling devices. Thus, when the second coupling device DC2 is in its fully decoupled (or completely open) state, only the electric motor MME can supply torque upstream of the first coupling device DC1.

[0050] For example, this second DC2 coupling device could be a clutch.

[0051] It should also be noted that in the example illustrated (non-exhaustively) in Figure 1, the first coupling device DC1, the possible second coupling device DC2, the electric drive machine MME, and the gearbox BV are part of a gearbox assembly EBV. However, this is not mandatory.

[0052] The accelerator pedal PA is operated (here) by a foot of the driver of vehicle V. It has a percentage of depressment from which the torque setpoint ccg is defined, which is then representative of the driver's intention.

[0053] The speed control unit (CA) provides at least one speed control function (FCV) within the vehicle (V) during assisted speed control phases, during which it controls the vehicle's current speed (vv) based on a speed setpoint (cv). In the following, as a non-limiting example, the speed control function FCV is considered a speed limiting function which, when activated, generates a torque setpoint (ccg) that prevents the vehicle (V) from exceeding a speed setpoint (cv). This generated torque setpoint (ccg) is then transmitted to the supervisory control unit (CS).

[0054] In fact, the torque setpoint ccg is determined by the speed control function FCV based on an acceleration that it has determined based on the difference between the speed setpoint cv to be respected and the current speed vv of the vehicle V and minimum and maximum accelerations which are a function of this difference.

[0055] However, the invention is not limited to this type of speed control function. It relates to any type of speed control function capable of generating a torque command based on a speed command. Thus, the FCV speed control function could also be a speed regulation function, a speed limiting function, or even a speed and distance control function between vehicles (or ACC ("Adaptive Cruise Control")), for example.

[0056] It should be noted that the speed control computer CA and the supervision computer CS can, for example, communicate via an internal RC communication network of the vehicle V, possibly multiplexed, as illustrated non-limitingly in Figure 1.

[0057] Vehicle V also offers two regenerative braking modes, selectable by the driver, which allow for the recovery of regenerative braking torques with respective levels of the first (n1) and second (n2). In this case, the first level (n1, referred to as "low" or "sweeping") is lower than the second level (n2, referred to as "high," or "brake"). It is important to note that when a level is mentioned, it is an absolute value.

[0058] As mentioned above, the invention proposes in particular a control method intended to allow control of the use of the first m1 and second m2 regenerative braking modes of the vehicle V, when the first regenerative braking mode m1 has been selected by the driver and the FCV speed control function has been activated (for example by the driver).

[0059] This control method can be implemented at least partially by the DC3 control device (illustrated at least partially in Figures 1 and 2), which comprises at least one PR1 processor, for example, a digital signal processor (DSP), and at least one MD memory. This DC3 control device can therefore be implemented as a combination of electrical or electronic circuits or components (or "hardware") and software modules. For example, it could be a microcontroller.

[0060] The MD memory is random access memory (RAM) to store instructions for the PR1 processor to implement at least part of the control process. The PR1 processor may include integrated circuits (or printed circuit boards), or several integrated circuits (or printed circuit boards) connected by wired or wireless connections. An integrated circuit (or printed circuit board) is defined as any type of device capable of performing at least one electrical or electronic operation.

[0061] In the example illustrated (but not limited to) in Figures 1 and 2, the DC3 control unit is part of the CS supervisory control unit. However, this is not mandatory. The DC3 control unit could have its own dedicated control unit, or it could be part of another control unit installed in the vehicle (V) that performs at least one other function, such as the CA speed control unit.

[0062] As illustrated non-limitingly in Figure 3, the (control) method according to the invention includes a step 10-50 which is implemented each time the FCV speed control function has been activated.

[0063] Step 10-50 of the process includes a substep 30 in which, when the first regenerative braking mode m1 is selected, and when a first target acceleration ac1 required by the speed control function FCV is less than a potential minimum acceleration amp that can be ensured by the GMP in the first regenerative braking mode m1, the use of the second regenerative braking mode m2 is imposed (for example, the control device DC3 triggers the imposition of) to maintain the speed setpoint cv.

[0064] It will be understood that we are talking here about accelerations which are negative, and therefore a first acceleration is less than a second acceleration when its absolute value is greater than that of the second acceleration.

[0065] By mandating (or forcing) the use of the second regenerative braking mode m2 instead of the selected first regenerative braking mode m1, it is now possible to recover (much) more regenerative braking torque, and therefore decelerate (or brake) (much) more strongly, while using the vehicle's braking system (much) less frequently. It is thus now possible to reach the target speed cv more quickly, but also, at the same time, to convert a greater amount of regenerative braking torque into electrical energy to recharge the rechargeable battery BR, for example, to provide vehicle V with a greater driving range.

[0066] The invention is therefore particularly advantageous, although not exhaustively, when the vehicle V is on a downward slope.

[0067] Furthermore, the invention makes the speed control functions robust to the gradient of the traffic lanes, regardless of the driving mode selected by the driver. In addition, the invention allows for completely transparent operation for the driver.

[0068] For example, and as illustrated (non-limitingly) in Figure 3, step 10-50 of the process may include a substep 20 in which the first target acceleration ac1 required by the speed control function FCV can be compared to the minimum potential acceleration amp that can be achieved by the powertrain in the first regenerative braking mode m1. If the first target acceleration ac1 is greater than the minimum potential acceleration amp, step 10-50 of the process can be repeated. Conversely, if the first target acceleration ac1 is less than the minimum potential acceleration amp, substep 30 is performed.

[0069] For example, and as illustrated (but not limited to) in Figure 3, step 10-50 of the process may include a substep 10 in which one (e.g., the control device DC3) can first determine whether the first regenerative braking mode m1 has been selected, given that the speed control function FCV is activated. If not, one (e.g., the control device DC3) can repeat step 10-50 of the process. Conversely, if it has (first regenerative braking mode m1 selected), one (e.g., the control device DC3) performs substep 20.

[0070] Also, for example, and as illustrated non-limitingly in Figure 3, step 10-50 of the process may include a substep 40 in which, once the second regenerative braking mode m2 has been imposed in substep 30, one (for example, the control device DC3) can determine whether a second (or other) target acceleration ac2, defined as a function of the percentage of accelerator pedal depressed PA, is less than the potential minimum acceleration amp. If so, one (for example, the control device DC3) can maintain the imposition of the second regenerative braking mode m2, and therefore we (for example the DC3 control device) can perform substep 30 again.

[0071] This option is designed to determine if there is a potential conflict between the driver's intent, represented by the second (or other) target acceleration ac2, and the need for regenerative braking torque recovery from the FCV speed control function. It is understood that the driver's intent takes precedence over regenerative braking torque recovery. In other words, if the driver wants to brake their vehicle V, for example because they are getting too close to the vehicle in front, they will press the accelerator pedal PA less, and therefore the absolute value of the second (or other) target acceleration ac2 will be greater than that of the minimum potential acceleration amp, which means that the second regenerative braking mode m2 must be maintained.

[0072] Conversely, when the second (or other) target acceleration is greater than the potential minimum acceleration amp in substep 40, the imposition of the (e.g., the DC3 control device can trigger the cessation of the imposition of) second regenerative braking mode m2 in a substep 50 of step 10-50 can cease, as illustrated non-limitingly in Figure 3.

[0073] It is understandable that there is a potential conflict between the driver's intent, represented by the second (or other) target acceleration ac2, which indicates that they do not want even slight braking, and the need for regenerative braking torque recovery from the FCV speed control function. Therefore, the second regenerative braking mode m2 must no longer be enforced.

[0074] It should also be noted, as illustrated (but not limited to) in Figure 2, that the CS supervisory computer (or the DC3 control device computer) may also include a mass storage unit MM1, notably to store the speed setpoint cv, the first target acceleration ac1, the second target acceleration ac2, and the potential minimum acceleration amp, as well as any intermediate data involved in all its calculations and processing. Furthermore, this computer The CS supervision unit (or the DC3 control unit) may also include an IE input interface for receiving at least the speed setpoint cv, the first target acceleration ac1, the second target acceleration ac2, and the potential minimum acceleration amp, optionally after shaping and / or demodulating and / or amplifying them, in a manner known per se, by means of a PR2 digital signal processor. Furthermore, this CS supervision unit (or the DC3 control unit) may also include an IS output interface, notably for delivering each message containing a command to enforce the second regenerative braking mode m2 or each message containing a command to stop the enforcement of the second regenerative braking mode m2.

[0075] It should 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 type of electronic circuits (or hardware), such as for example the PR1 processor, is suitable for implementing the control method described above to control the use of the first m1 and second m2 regenerative braking modes when the first regenerative braking mode m1 has been selected in the vehicle V.

Claims

CLAIMS

1. Control method for a land vehicle (V) and comprising i) an accelerator pedal (PA), ii) a speed control function capable, in the event of activation, of controlling a current speed of said vehicle (V) as a function of a speed setpoint, and iii) a powertrain capable of providing first and second selectable regenerative braking modes and making it possible to recover in said vehicle (V) regenerative braking torques having respectively first and second levels, said first level being lower than said second level, characterized in that it comprises a step (10-50) in which, when said first regenerative braking mode is selected, and when a target acceleration required by said speed control function is lower than a potential minimum acceleration that can be provided by said powertrain in said first regenerative braking mode,the use of said second regenerative braking mode is required to comply with said speed instruction.,

2. Method according to claim 1, characterized in that in said step (10-50), once said second regenerative braking mode has been imposed, it is determined whether another target acceleration, defined as a function of a percentage of depression of said accelerator pedal (PA), is lower than said potential minimum acceleration, and if so, the imposition of said second regenerative braking mode is maintained.

3. Method according to claim 2, characterized in that in said step (10-50), when said other target acceleration is greater than said potential minimum acceleration, said second regenerative braking mode is no longer imposed.

4. 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 3, in a land vehicle (V) and comprising i) an accelerator pedal (PA), ii) a speed control function capable, in the event of activation, of controlling a current speed of said vehicle (V) as a function of a speed setpoint speed, and iii) a powertrain capable of providing first and second selectable regenerative braking modes and making it possible to recover in said vehicle (V) regenerative braking torques having first and second levels respectively, said first level being lower than said second level, to control the use of said first and second regenerative braking modes when said first regenerative braking mode has been selected.

5. Control device (DC3) for a land vehicle (V) and comprising i) an accelerator pedal (PA), ii) a speed control function capable, in the event of activation, of controlling a current speed of said vehicle (V) as a function of a speed setpoint, and iii) a powertrain capable of providing first and second selectable regenerative braking modes and making it possible to recover in said vehicle (V) regenerative braking torques having respectively first and second levels, said first level being lower than said second level, 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 first regenerative braking mode is selected,and when a target acceleration required by said speed control function is less than a minimum potential acceleration that can be provided by said powertrain in said first regenerative braking mode, triggering an imposition of the use of said second regenerative braking mode to meet said speed setpoint.,

6. Land vehicle (V) comprising i) an accelerator pedal (PA), ii) a speed control function capable, when activated, of controlling a current speed of said vehicle (V) as a function of a speed setpoint, and iii) a powertrain capable of providing first and second selectable regenerative braking modes and making it possible to recover in said vehicle (V) regenerative braking torques having first and second levels respectively, said first level being lower than said second level, characterized in that it further comprises a control device (DC3) according to claim 5.

7. Vehicle according to claim 6, characterized in that it comprises a rechargeable battery (BR) capable of storing electrical energy, and in that said powertrain comprises at least one electric motor (MME) capable of recovering said regenerative braking torque and transforming said recovered regenerative braking torque into electrical energy to recharge said rechargeable battery (BR).

8. Vehicle according to claim 6 or 7, characterized in that it is of the automobile type.

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