A method for controlling the prime mover by predicting the set speed during the synchronization phase.

Abstract

The present invention relates to a method for controlling a prime mover (18) mounted on an axle (19) of a motor vehicle equipped with wheels (19.1), the prime mover (18) being associated with a coupling and disconnection device (23) capable of selectively engaging or disengaging the prime mover (18) from the axle (19) of the motor vehicle. During a synchronization phase between the rotational speed of the prime mover (18) and the rotational speed of the wheels (19.1), there may be a discrepancy in the reduction ratio of a reducer if necessary. The method includes: a determination step for determining a set rotational speed of the prime mover (18) based on a target rotational speed to be achieved by the prime mover (18) according to the derivative of time and based on a delay duration related to the acquisition of the set rotational speed; and a transmission step for transmitting the previously determined set rotational speed to a speed controller (28) of the prime mover (18).

Description

Technical Field

[0001] This invention claims priority to French application No. 1912979, filed on November 20, 2019, the contents of which (text, drawings and claims) are incorporated herein by reference.

[0002] This invention relates to a control method for manipulating a prime mover by predicting a set rotational speed during a synchronization phase. The invention is particularly advantageous for use with electric or hybrid traction chains, especially in motor vehicles. Background Technology

[0003] In a manner known per se, the traction chain of a motor vehicle may include a traction machine (particularly an electric motor) mounted on the rear axle of the motor vehicle and associated with a reduction gear and a connection and disconnection device for engaging and disengaging the traction electric motor from the rear axle. The reduction gear enables the very high rotational speed of the electric motor to be compatible with the rotational speed of the vehicle's wheels.

[0004] The connection and disconnection device enables the motor vehicle to operate in two modes: a first mode in which the electric motor is disconnected and awaits connection to the rear axle; and a second mode in which the electric motor is connected to the rear axle to provide additional power to the wheels of the motor vehicle.

[0005] Before connecting the traction machine to the axle of the vehicle, a synchronization phase is performed to synchronize the rotational speed of the prime mover with the rotational speed of the wheels, with the reduction ratio of the reducer adjusted as needed.

[0006] like Figure 1 As can be seen above, during this synchronization phase, the speed setpoint N_cns corresponding to the target speed N_phys_C that the prime mover is expected to reach is sent to the speed controller of the prime mover.

[0007] Because the multi-computer electronic architecture of the traction chain includes a global monitor separate from the speed controller of the prime mover, there may be a delay time T_ret between the moment when the set speed N_cns is generated by the monitor and the moment when the set speed N_cns is received and processed by the speed controller to manipulate the prime mover.

[0008] When the engine speed setpoint N_cns changes, for example, to follow vehicle acceleration, the delay T_ret causes a delay error (or lag error) in the obtained actual engine speed N_phys_R. The error N_er is a delay error. When the prime mover is connected to the claw clutch, this delay error may degrade the driving pleasure of the vehicle or even prevent the claw clutch from closing. Summary of the Invention

[0009] This invention aims to effectively overcome these drawbacks by providing a method for controlling a prime mover mounted on an axle of a motor vehicle equipped with wheels, the prime mover being associated with a coupling and disconnection device capable of selectively engaging or disengaging the prime mover from the axle of the motor vehicle. During the synchronization phase between the rotational speed of the prime mover and the rotational speed of the wheels, a discrepancy in the reduction ratio of a speed reducer is allowed as needed. The method includes:

[0010] - A determining step, the determining step being used to determine the set speed of the prime mover based on the derivative of time and based on a delay duration related to the acquisition of the set speed, and

[0011] - Sending step, the sending step being used to send the previously determined set speed to the speed controller of the prime mover.

[0012] Therefore, by taking into account the delay duration and the derivative of the target rotational speed when setting the rotational speed, the present invention can precisely control the rotational speed of the prime mover during the synchronization phase with the wheels of the vehicle, and thus can ensure the closure of the coupling and disconnection devices and the driving pleasure of the motor vehicle.

[0013] According to an embodiment, the set rotational speed N_cns of the prime mover is determined based on the following relationship:

[0014] N_cns=N_phys_C+T_ret×d(N_phys_C) / dt

[0015] -N_phys_C is the target rotational speed to be achieved by the prime mover.

[0016] -T_ret is the delay duration related to obtaining the set rotational speed.

[0017] The quantities N_cns, N_phys_C, and T_ret are signed quantities, and therefore can be either positive or negative.

[0018] According to an embodiment, the delay time associated with obtaining the set rotational speed corresponds to a duration between the following times:

[0019] - The time when the set rotation speed is generated by the monitor, and

[0020] The set speed is received and processed by a speed controller separate from the monitor.

[0021] The method according to the invention can be implemented to positively change the rotational speed of the prime mover.

[0022] The method according to the invention can be implemented by applying a negative change in the rotational speed of the prime mover.

[0023] The present invention also aims to provide a computer including a memory storing software instructions for implementing the control method for controlling a prime mover as defined above.

[0024] The present invention also aims to provide a motor vehicle, the motor vehicle comprising:

[0025] - Axles equipped with wheels,

[0026] -The prime mover mounted on the axle

[0027] - A connection and disconnection device associated with the prime mover, the connection and disconnection device being capable of selectively connecting or disconnecting the prime mover from the axle.

[0028] - Computers as defined above.

[0029] The prime mover is, for example, a traction motor.

[0030] The connection and disconnection device is, for example, a claw clutch.

[0031] The vehicle includes, for example, a reduction gear, and the connection and disconnection device is associated with the reduction gear.

[0032] The axle is, for example, the rear axle of the vehicle. Attached Figure Description

[0033] The invention will be better understood by reading the following detailed description and accompanying drawings, in which:

[0034] -As already described Figure 1 It is a graph showing the evolution of the actual rotational speed of the prime mover, the desired target rotational speed, and the set rotational speed generated without delay compensation according to the method of the prior art over time.

[0035] - Figure 2 This is a schematic diagram of an example of a traction chain for a motor vehicle implementing the control method according to the present invention;

[0036] - Figure 3It is a graph showing the evolution over time of the actual rotational speed of the prime mover, the desired target rotational speed, and the set rotational speed generated with delay compensation by the method according to the invention. Detailed Implementation

[0037] Figure 2 A traction chain 10 for a motor vehicle is shown, comprising a heat engine 11 and a traction motor 12 mounted on the axle 13 (particularly the front axle) of the motor vehicle. The heat engine 11 is, for example, a four-cylinder heat engine. In variations, the heat engine 11 may of course include different numbers of cylinders, particularly three or more than four. The heat engine 11 may be associated with a starter to ensure cold starting of the heat engine.

[0038] The heat engine 11 is connected to the gearbox 15 via a clutch 16. The output shaft of the gearbox 15 is connected to the wheels via a differential (not shown). The gearbox 15 is, for example, an automatic gearbox (especially an automatic gearbox with a planetary gear system).

[0039] The traction motor 12 is positioned between the clutch 16 and the gearbox 15. Thus, when the motor 12 ensures that the vehicle is towed in electric driving mode, the clutch 16 can isolate the traction motor 12 from the heat engine 11.

[0040] The prime mover 18 is mounted on the rear axle 19 of the vehicle by means of a reduction gear 22 and a connection and disconnection device 23 for connecting and disconnecting the traction motor 18 from the rear axle 19. In this example, the prime mover 18 is a second traction motor. In a variant, the prime mover 18 may be in the form of a thermal engine or a hydraulic engine.

[0041] The connection and disconnection device 23 can be in an open state and a closed state. In the open state, the traction motor 18 is disconnected from the rear axle 19, and in the closed state, the traction motor 18 is connected to the rear axle 19. The connection and disconnection device 23 is preferably a device with a claw clutch. In a variant, the connection and disconnection device 23 is a clutch.

[0042] Battery 24 is electrically connected to traction motor 12 and traction motor 18. Battery 24 is shared by both traction motors 12 and 18. In a variant, a battery 24 is used that is associated with each traction motor 12 and 18 separately.

[0043] The first traction motor 12 and the second traction motor 18 may have high operating voltages (especially voltages greater than 48 volts).

[0044] Traction motors 12 and 18 are capable of converting electrical energy from battery 24 into mechanical energy to ensure traction of the vehicle. Traction motors 12 and 18 are also capable of operating in generator mode, in which they convert mechanical energy into electrical energy, which can recharge battery 24, especially during regenerative braking phases.

[0045] This architecture enables the vehicle to operate in pure thermal mode, hybrid propulsion mode, pure electric propulsion mode, 4x4 hybrid mode, and 4x4 electric mode.

[0046] The monitor 26 ensures control over the different components of the traction chain 10. The monitor 26 may be in the form of a computer, which includes a memory storing software instructions for implementing the control method for manipulating the traction chain 10 according to the invention.

[0047] More precisely, during the synchronization phase between the rotational speed of the prime mover 18 and the rotational speed of the wheels 19.1 of the axle 19, there is a discrepancy in the reduction ratio of the reducer when necessary. The monitor 26 determines the set rotational speed N_cns of the prime mover 18, such as... Figure 3 As shown above, "rotation speed" can be understood as the rotational speed of the corresponding component.

[0048] The set speed N_cns is determined based on the target speed N_phys_C to be reached by the prime mover 18, according to the derivative of time and based on the delay T_ret associated with the acquisition of the set speed N_cns. ​​The target speed N_phys_C to be reached corresponds to the speed of the wheel 19.1, which may vary depending on the reduction ratio of the reducer if necessary.

[0049] The monitor 26 then sends the previously determined set speed N_cns to the speed controller 28 of the prime mover 18, which is separate from the monitor 26. The monitor 26 and the speed controller 28 communicate with each other via a communication network (especially a CAN (Controller Area Network) or FlexRay (registered trademark) type network).

[0050] The delay duration T_ret corresponds to the time between the moment when the set speed N_cns is generated by the monitor 26 and the moment when the set speed N_cns is received and processed by the speed controller 28 to manipulate the prime mover 18.

[0051] More precisely, the rotational speed N_cns is determined based on the following relationship:

[0052] N_cns=N_phys_C+T_ret×d(N_phys_C) / dt

[0053] -N_phys_C is the target speed to be achieved by the prime mover 18.

[0054] -T_ret is the delay duration related to obtaining the set rotational speed.

[0055] Therefore, by taking into account the variation (derivative) of the desired rotational speed N_phys_C, the setpoint N_cns is predicted in order to minimize the final adjustment error.

[0056] The actual rotational speed N_phys_R of the prime mover 18 thus coincides with the desired target rotational speed N_phys_C.

[0057] exist Figure 3 In the above, N_phys_C_grad corresponds to the time-dependent change of the desired target rotational speed N_phys_C, and the deviation N_cns_off between the set rotational speed N_cns and the desired target rotational speed N_phys_C is equal to the product of N_phys_C_grad and the delay duration T_ret.

[0058] The method according to the invention can be implemented for both positive speed changes of the prime mover 18 (when the vehicle is accelerating) and negative speed changes (when the vehicle is decelerating).

[0059] In a variant, the structure of the traction chain 10 can be inverted, that is, the traction motor 12 and the heat engine 11 are mounted on the rear axle 19 of the vehicle, while the traction motor 18, the reducer 22, and the coupling and disconnection device 23 are mounted on the front axle 13 of the vehicle.

Claims

1. A method for handling a prime mover (18) fitted on an axle (19) equipped with wheels (19.1) of a motor vehicle, said prime mover (18) being associated with a coupling and uncoupling device (23) capable of selectively coupling or uncoupling said prime mover (18) with said axle (19) of the motor vehicle, characterized in that, During a phase of synchronization of the rotation speed of the prime mover (18) with the rotation speed of the wheels (19.1), the piloting method comprises, if necessary, an entry or exit of the reduction ratio of the reduction gear, the piloting method comprising: - a determination step for determining a set rotation speed N_cns of the prime mover (18) based on the derivative of the target rotation speed N_phys_C to be reached by the prime mover (18) as a function of time and based on a delay duration T_ret related to the obtaining of the set rotation speed N_cns of the prime mover, and - a sending step for sending the set rotation speed N_cns previously determined to a rotation speed controller (28) of the prime mover (18).

2. The handling method according to claim 1, characterized in that, The set rotation speed N_cns of the prime mover (18) is determined based on the following relationship: N_cns = N_phys_C + T_ret x d(N_phys_C) / dt - N_phys_C is the target rotation speed to be reached by the prime mover (18), - T_ret is the delay duration related to the obtaining of the set rotation speed.

3. The handling method according to claim 1 or 2, characterized in that, The delay duration T_ret related to the obtaining of the set rotation speed N_cns corresponds to the duration between: - the time at which the set rotation speed N_cns is generated by a monitor (26), and - the time at which the set rotation speed N_cns is received and processed by a rotation speed controller (28) separate from the monitor (26).

4. The handling method according to claim 1 or 2, characterized in that, The piloting method is implemented for a positive variation of the rotation speed of the prime mover (18).

5. The handling method according to claim 1 or 2, characterized in that, The piloting method is implemented for a negative variation of the rotation speed of the prime mover (18).

6. A computer comprising a memory storing software instructions for implementing a piloting method for piloting a prime mover (18) as defined in any one of claims 1 to 5.

7. A motor vehicle comprising: - an axle (19) equipped with wheels (19.1), - a prime mover (18) fitted on the axle (19), - a coupling and uncoupling device (23) associated with the prime mover (18), the coupling and uncoupling device being able to selectively couple or uncouple the prime mover (18) with the axle (19), characterized in that it further comprises a computer as defined in claim 6.

8. Motor vehicle according to claim 7, characterized in that The prime mover (18) is a traction electric motor.

9. Motor vehicle according to claim 7 or 8, characterized in that The coupling and uncoupling device (23) is a dog clutch.

10. Motor vehicle according to claim 7 or 8, characterized in that The motor vehicle comprises a reduction gear, the coupling and uncoupling device (23) being associated with the reduction gear.

11. Motor vehicle according to claim 7 or 8, characterized in that The axle (19) is a rear axle of the motor vehicle.

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