阅读说明：本技术 用于控制混合动力推进式机动车辆的无离合器自动变速器的方法和系统 (Method and system for controlling a clutchless automatic transmission of a hybrid propulsion motor vehicle ) 是由 A·沙默鲁瓦 F·布福 N·本-贝尔迪 于 2018-11-09 设计创作，主要内容包括：披露了一种用于控制混合动力推进式机动车辆的变速器的至少一个变速箱致动器的方法,该混合动力推进式机动车辆包括内燃发动机和至少一个电动机器,所述变速器包括至少一个爪形离合器系统,该至少一个爪形离合器系统包括紧固至能够在传动轴上自由旋转的怠速齿轮的爪以及紧固至滑动件的爪,该滑动件可旋转地紧固至主轴,该滑动件被配置为通过该变速箱致动器而沿着该传动轴的轴线纵向移动,以使这些爪接合或脱离接合。为了使这些爪脱离接合,该方法涉及：通过将动力学基本原理应用于要脱离接合的爪(6)来计算用于消除该爪处的转矩(C<Sub>c</Sub>)的马达转矩设定值(C<Sub>m_sp</Sub>)；将计算出的所述马达转矩设定点(C<Sub>m_sp</Sub>)遵循线性减小的第一斜率传输至该马达,直到该爪处的转矩达到阈值(C<Sub>S1</Sub>)；将该爪处的转矩(C<Sub>c</Sub>)与该阈值(C<Sub>S1</Sub>)进行比较；以及当该爪处的转矩(Cc)小于或等于该阈值(C<Sub>S1</Sub>)时,通过发送位置设定值(P<Sub>_sp</Sub>)来控制该变速箱致动器(8),以触发该滑动件(7)的移动,从而使这些爪(6)脱离接合。(A method is disclosed for controlling at least one gearbox actuator of a transmission of a hybrid propelled motor vehicle comprising an internal combustion engine and at least one electric machine, said transmission comprising at least one dog clutch system comprising a dog fastened to an idle gear free to rotate on a drive shaft and a dog fastened to a slide rotatably fastened to a spindle, the slide being configured to be moved longitudinally along the axis of the drive shaft by the gearbox actuator to engage or disengage the dogs. In order to make theseThe jaws are disengaged, the method involving: calculating a torque (C) for eliminating a claw (6) to be disengaged by applying the basic principle of dynamics to the claw c ) Motor torque set value (C) m_sp ) (ii) a (ii) calculating the motor torque setpoint (C) m_sp ) Following a first slope of linear decrease, until the torque at the pawl reaches a threshold value (C) S1 ) (ii) a Torque (C) at the claw c ) And the threshold value (C) S1 ) Comparing; and when the torque (Cc) at the claw is less than or equal to the threshold value (C) S1 ) By sending the position set value (P) _sp ) To control the gearbox actuator (8) to trigger movement of the slider (7) to disengage the jaws (6).)

1. A method for controlling at least one gearbox actuator (8) of a transmission (1) of a hybrid propelled motor vehicle comprising an internal combustion engine and at least one electric machine, the transmission (1) comprising: a motor shaft (2) which is directly or indirectly connected to the internal combustion engine and/or the electric machine; a propeller shaft (3) connected to the driven wheels of the motor vehicle; and at least one coupling system comprising, on the one hand, a coupling jaw (5) fastened to an idle pinion (4) freely rotatably supported on the drive shaft (3) and, on the other hand, a coupling jaw (6) fastened to a slider (7) rotating with the motor shaft (2), the slider (7) being configured to be moved longitudinally along the axis of the drive shaft (3) by means of the gearbox actuator (8) to engage or disengage the coupling jaws (5, 6), characterized in that, in order to disengage the coupling jaws (5, 6):

-calculating a torque (C) for eliminating a coupling jaw (6) to be disengaged by applying the basic principle of dynamics to the coupling jaw_c) Motor torque set point (C)_{m_sp})；

-calculating said motor torque setpoint (C)_{m_sp}) Following a first slope (P1) which decreases linearly to the motor until the torque at the coupling pawl reaches a threshold value (C)_S1) Until then;

-torque (C) at the coupling pawl_c) And the threshold value (C)_S1) Comparing; and

-torque (C) at the coupling pawl_c) Is less than or equal to the threshold value (C)_S1) By sending a position set point (P)_{_sp}) The gearbox actuator (8) is operated to trigger the movement of the slide (7) to disengage the coupling pawl (6) in question by moving the slide towards the neutral position.

2. The method of claim 1, wherein the position of the slide (7) is verified and the motor torque setpoint (C) is maintained with a second slope (P2) having a smaller dynamic gradient than that of the first slope (P1)_{m_sp}) Until the slider (7) is in the neutral position, to eliminate the torque at the coupling pawl.

3. The method of claim 1 or 2, wherein the target value (C) of the torque at the coupling claw is dependent on_{c _ target}) To calculate the motor torque setpoint (C) for eliminating the torque at the coupling pawl_{m_sp}) Calculating a target value of the torque at the coupling pawl in such a manner that the torque at the coupling pawl (C) is obtained_c) Is less than or equal to the threshold value (C)_S1)。

4. Method according to any one of the preceding claims, wherein a lower than actual target value (C) is defined_{c _ actual target}) Is a target value (C) of torque at the coupling claw_{c _ target}) In order to ensure a torque (C) at the coupling pawl_c) Towards the threshold (C)_S1) And (6) converging.

5. A transmission (1) for a hybrid propelled motor vehicle comprising an internal combustion engine and at least one electric machine, said transmission (1) comprising: a motor shaft (2) which is directly or indirectly connected to the internal combustion engine and/or the electric machine; a propeller shaft (3) connected to the driven wheels of the motor vehicle; and at least one coupling system comprising, on the one hand, a coupling pawl (5) fastened to an idle pinion (4) freely rotatably supported on the drive shaft (3) and, on the other hand, a coupling pawl (6) fastened to a slide (7) rotating with the motor shaft (2), the slide (7) being configured to be moved longitudinally along the axis of the drive shaft (3) by means of the gearbox actuator (8) to engage or disengage the coupling pawls (5, 6), characterized in that the transmission comprises an electronic control unit (10) comprising a control system (11) comprising:

-for calculating a torque (C) for eliminating a coupling jaw (6) to be disengaged by applying a basic principle of dynamics to the coupling jaw_c) Motor torque set point (C)_{m_sp}) A module (12);

-for calculating the motor torque setpoint (C)_{m_sp}) Following a first slope (P1) which decreases linearly to the motor until the torque at the coupling pawl reaches a threshold value (C)_S1) A module (13) up to time;

-torque (C) for coupling the coupling pawl_c) And the threshold value (C)_S1) A module (14) for performing the comparison; and

-a control module (15) for torque (C) at the coupling pawl_c) Is less than or equal to the threshold value (C)_S1) By setting the position set point (P)_{_sp}) To the slider (7) to control the gearbox actuator (8) to allow the coupling claw (6) in question to be disengaged by moving the slider towards the neutral position.

6. The transmission (1) as claimed in claim 5, wherein the control system (11) comprises a module (16) for verifying the position of the slide, and a module for maintaining the motor torque setpoint (C) with a second slope (P2) having a dynamic gradient smaller than that of the first slope (P1)_{m_sp}) So as to eliminate the torque at the coupling jaws until the slider (7) is in the module (17) of neutral position.

7. Hybrid propelled motor vehicle comprising a transmission according to one of claims 5 and 6.

Technical Field

The present invention relates to the field of developing control strategies for automatic transmissions.

More particularly, the invention relates to transmissions for motor vehicles comprising, on the one hand, an internal combustion engine for driving and, on the other hand, at least one electric machine. Such hybrid transmissions generally comprise two concentric primary shafts, each supporting at least one pinion which engages down onto a secondary shaft connected to the wheels of the vehicle.

Background

Hybrid transmissions are beneficial in that they provide two sources of energy, combustion and electrical power, to the driveline for propelling the vehicle. The torque contributions of these two energy sources may be combined in a "hybrid" mode or may be employed separately in a "engine-only" mode (in which the electric machine does not provide any torque to the driveline) or in what is known as an "electric-only" mode (in which the internal combustion engine does not provide any torque to the driveline).

Hybrid transmissions allow an internal combustion engine to be driven using an electric machine as a starter when deactivated or running. The hybrid transmission also allows the battery of the vehicle to be charged by the electric machine operating in the generator mode.

Documents WO 2012/131259-a1 (reynolds) and EP 2726757-B1 (reynolds) describe the architecture of said hybrid transmission, which comprises a main line comprising: a solid main shaft connected to a flywheel of an internal combustion engine and supporting an idle pinion connectable to said solid shaft by a first coupling system of the claw coupling type; and a hollow main shaft concentric with the solid main shaft, the hollow main shaft being connected to the rotor of the electric machine and supporting a stationary pinion, which may be connected to the solid shaft by a first coupling system.

The transmission also comprises a secondary shaft supporting two idle pinions which can be connected to the primary shaft by a second coupling system of the claw coupling type. The layshaft also supports a fixed pinion and a pinion that is coupled downwardly to a differential that is connected to the driven wheels of the vehicle.

To allow for changing the transmission ratio, it must be possible to disengage the pinion under all foreseeable circumstances. In addition, it is also important to optimize the decoupling time in order to minimize the driver's feeling and improve the drivability.

Documents US 6371879B 1 (hitachi) and US 5456647-a (cleisler) are known and describe automatic transmission control units configured to transmit driving force from a motor to an axle based on slipping of a clutch and control of a hydraulic unit to cause slipping of a belt/pulley mechanism, allowing one gear ratio to be disengaged and the other gear ratio to be engaged.

However, this control method involves a transmission including a clutch, and is not applicable to a clutch-less hybrid transmission.

This is because there is no mechanical coupling system in such a clutchless hybrid transmission.

Disclosure of Invention

It is therefore an object of the present invention to mitigate these drawbacks and to propose a method and a system for controlling a clutchless hybrid transmission.

One subject of the invention is a method for controlling at least one gearbox actuator of a transmission of a clutchless hybrid propelled motor vehicle comprising an internal combustion engine and at least one electric machine, said transmission comprising: a motor shaft directly or indirectly connected to the internal combustion engine and/or the electric machine; a drive shaft connected to a driven wheel of the motor vehicle; and at least one coupling system comprising, on the one hand, a coupling claw fastened to an idle pinion freely rotatably supported on the drive shaft and, on the other hand, a coupling claw fastened to a slide rotating with the motor shaft, the slide being configured to be moved longitudinally along the axis of the drive shaft by the gearbox actuator to engage or disengage the coupling claws.

In order to disengage the coupling jaws, a motor torque setpoint for eliminating the torque at the coupling jaw is calculated by applying the basic principle of dynamics to the coupling jaw to be disengaged; transmitting the calculated motor torque setpoint to the motor following a first slope that decreases linearly until the torque at the coupling jaw reaches a threshold value, based on which the coupling jaw may be allowed to disengage, the torque at the coupling jaw being compared to the threshold value; and operating the gearbox actuator by sending a position set point to trigger movement of the slider to disengage the coupling pawl in question by moving the slider towards the neutral position when the torque at the coupling pawl is less than or equal to the threshold value.

The motor is therefore controlled in such a way as to reduce the level of torque it provides following a curve of the linear reduction type until the motor torque setpoint is reached.

Advantageously, the position of the slider is verified and the transmission of the motor torque setpoint is maintained with a second slope having a dynamic gradient smaller than that of the first slope so as to eliminate the torque at the coupling pawl until the slider is in the neutral position.

In this way it can be ensured that the torque at the dog clutch will reach the target value as soon as the slider has finished moving the coupling dogs out of engagement, i.e. the torque at the coupling dogs will cross the disengagement window for a longer time than the time needed to move the slider.

Thus, the torque of the motor and the movement of the gearbox actuator are controlled together in order to ensure that the force resisting the movement of the gearbox actuator is lower than the ability to move said gearbox actuator for a certain duration to allow the coupling pawl to disengage.

For example, the motor torque set point for eliminating the torque at the coupling pawl is calculated from a target value of the torque at the coupling pawl in such a manner that the value of the torque at the coupling pawl obtained is less than or equal to the threshold value.

The motor torque set point for eliminating the torque at the coupling claw is calculated, for example, from the radial inertia of the rotor of the motor, from the reduction ratio between the engine speed and the wheel speed, and from the derivative of the engine speed with respect to time for estimating the inertial component of the force at the coupling claw.

For example, a target value of the torque at the coupling pawl may be defined that is lower than an actual target value (e.g., equal to 0n.m) in order to ensure that the torque at the coupling pawl converges toward the threshold value.

According to a second aspect, the invention relates to a transmission for a hybrid propelled motor vehicle comprising an internal combustion engine and at least one electric machine. The transmission is clutchless and includes: a motor shaft directly or indirectly connected to the internal combustion engine and/or the electric machine; a drive shaft connected to a driven wheel of the motor vehicle; and at least one coupling system comprising, on the one hand, a coupling claw fastened to an idle pinion freely rotatably supported on the drive shaft and, on the other hand, a coupling claw fastened to a slide rotating with the motor shaft, the slide being configured to be moved longitudinally along the axis of the drive shaft by the gearbox actuator to engage or disengage the coupling claws.

The transmission includes an electronic control unit including a control system comprising: means for calculating a motor torque setpoint for eliminating torque at a coupling jaw to be disengaged by applying a dynamic rationale to the coupling jaw; means for transmitting the calculated motor torque setpoint to the motor following a linearly decreasing first slope until a torque at the coupling jaw reaches a threshold value beyond which the coupling jaw may be allowed to disengage; means for comparing the torque at the coupling pawl to the threshold; and a control module for controlling the gearbox actuator by sending a position set point to the slider when the torque at the coupling pawl is less than or equal to the threshold value, thereby allowing the coupling pawl in question to be disengaged by moving the slider towards the neutral position.

The motor is therefore controlled in such a way as to reduce its level of torque supplied while following a curve of the linear reduction type until it reaches the setpoint motor torque.

Advantageously, the control system comprises a module for verifying the position of the slider, and a module for maintaining the motor torque setpoint with a second slope having a dynamic gradient smaller than that of the first slope so as to eliminate the torque at the coupling pawl until the slider is in the neutral position.

Thus, it can be ensured that the torque at the coupling pawl will reach the target value as soon as the slider has completed a movement which disengages the coupling pawl, i.e. the torque at the coupling pawl will pass through the decoupling window for a longer time than the time required to move the slider.

In this way, the control system is configured to control the torque of the motor and the movement of the gearbox actuator together in order to ensure that the force resisting the movement of the gearbox actuator is lower than the ability to move said gearbox actuator for a certain duration of time, in order to allow the coupling pawl to disengage.

According to a third aspect, the invention relates to a hybrid propelled motor vehicle comprising a transmission as described above.

"Motor" refers to an internal combustion engine and/or one or more electric machines.

Drawings

Further objects, features and advantages of the present invention will become apparent from reading the following description, given by way of non-limiting example only and made with reference to the accompanying drawings, in which:

figure 1 very schematically depicts an architecture of a motor vehicle transmission according to an embodiment of the invention;

FIG. 2 is a graph illustrating the torque set point at the dog clutch as a function of time; and is

Fig. 3 is a flow chart of a method for controlling the transmission of fig. 1.

Detailed Description

As very schematically illustrated in fig. 1, the transmission, globally indicated with reference numeral 1, is intended to be incorporated into a hybrid-propelled motor vehicle (not shown) comprising, on the one hand, an internal combustion engine (not shown) and, on the other hand, one or two electric machines (not shown), each intended to drive a propeller shaft, which drives driven wheels (not shown).

In fig. 1, the architecture of the transmission 1 has been simplified to show a motor shaft 2 connected to an internal combustion engine or an electric machine or two motors (an internal combustion engine and an electric machine), and a propeller shaft 3 connected to driven wheels of a motor vehicle. In the rest of the description, the term "motor" will cover either an internal combustion engine, or an electric machine.

The transmission shaft 3 supports an idle pinion 4 that can rotate freely and comprises coupling jaws 5 intended to engage with coupling jaws 6 of a slider 7 fastened to the motor shaft 2. The slide 7 is moved longitudinally along the axis of the drive shaft 3 by a gearbox actuator 8.

This longitudinal movement allows the coupling pawls 5, 6 to engage with each other to connect the motor shaft 2 to the driven wheel at a fixed downshift gear ratio, or allows the coupling pawls 5, 6 to disengage to allow the motor shaft 2 to rotate freely.

The gearbox actuator 8 has a limited capacity due to the forces resisting its movement. Specifically, the shape of the coupling claws 5, 7 (forming a certain angle) generates a longitudinal component of a reaction force generated by a resultant force of torques applied to the motor shaft 2 and the drive shaft 3. There is also a friction force resisting the movement that creates them. These two forces are proportional to the torque existing between the motor shaft 2 and the drive shaft 3.

The transmission 1 comprises an electronic control unit ECU 10 comprising a transmission control system 11 configured to provide a common control of the motor torque and the gearbox actuator in order to ensure that the force resisting the movement of the gearbox actuator for a certain duration is weaker than the ability to move said gearbox actuator to allow the coupling pawls to disengage.

The torque between the motor shaft and the drive shaft corresponds to a resultant of the force applied by the motor torque and the inertial force. The inertial force is caused by the difference between the rotation speed of the motor shaft and the rotation speed of the driven wheel when the coupling pawl is engaged.

By applying the basic principle of dynamics to the coupling jaws to be disengaged, the following equation is obtained:

C_m-C_r＝C_c

wherein:

C_mis a motor torque corresponding to a torque obtained by the internal combustion engine or the electric machine or the motor combination, expressed at the level of the coupling pawls to be disengaged, using a downshift ratio of the gear ratio to be engaged as a factor;

C_rby taking the downshift sequence as a considerationTorque at the wheel represented by the level of the disengaged coupling pawl; and is

C_cIs the torque at the coupling jaw.

The system 11 comprises a motor torque setpoint C for calculating a torque for eliminating the torque at the coupling jaws_{m_sp}The module 12 of (a):

wherein:

C_{m_sp}is the motor torque set point;

I_mis the radial inertia of the motor rotor;

r is the reduction ratio between the rotational speed of the motor and the rotational speed of the wheel; and is

Is a derivative of the rotational speed with respect to time for estimating the inertial component of the force at the coupling jaw; and is

C_{c _ target}Is a target value of torque at the coupling claw; the target value of the torque at the coupling claw is calculated in such a manner that the torque C at the coupling claw is obtained_cIs below a threshold value C_S1Exceeding the threshold may allow the coupling jaws to disengage. The target value of the torque at the coupling pawl is then represented at the motor level by the reduction ratio.

The system 11 further comprises means for eliminating the torque C at the coupling jaws_cMotor torque setpoint C_{m_sp}To the module 13 of the motor.

In this way, the motor is commanded to reduce the level of torque it is providing following a curve of the linear reduction type with a first slope P1, illustrated in fig. 2, until a threshold C is reached_S1. Fig. 2 depicts a graph illustrating torque set point at the coupling jaws as a function of time. The vertical axis indicates torque in units of n.m, and the horizontal axis indicates time in units of s.

By way of non-limiting example onlyConsidering the initial torque at the coupling pawl of, for example, 60n.m, it is desirable to make the torque C at the coupling pawl_cTowards threshold C_S1(e.g., 5n.m) converge, and exceeding this threshold value considers the torque C at the coupling claw_cLow enough to allow operation of the actuator in order to disengage the slide. For this purpose, a motor torque setpoint C for eliminating the torque at the coupling jaws is calculated_{m_sp}Then, at each instant t, the torque setpoint is transmitted to the engine with a first slope P1 that decreases linearly, so as to bring the torque C at the coupling pawl_cTowards threshold C_S1And gradually converge.

However, uncertainty undermines the estimation of the inertial component of the force at the coupling jaws and the reliability of achieving the engine torque set point due to uncontrolled physical phenomena that may occur, such as motor response delays.

To overcome this, a definition is made, for example, equal to-5 n.m, i.e. lower than the actual target value C_{c _ actual target}Target value C of torque at coupling claw (0 N.m)_{c _ target}So as to ensure a torque C at the coupling pawl_cLess than or equal to a threshold value C_S1。

The system 11 further comprises means for coupling the torque C at the jaw_cAnd a threshold value C_S1Is compared and configured to verify the torque C at the coupling jaws_cWhether or not it is less than or equal to the threshold value C_S1And a torque C for coupling the jaws once_cLess than or equal to a threshold value C_S1By setting the position setpoint P_{_sp}A module 15 which is sent to the slider 7 to control the gearbox actuators to allow the coupling pawls in question to disengage by moving the slider towards the neutral position.

However, the gearbox actuator requires some time to move the slider and disengage the coupling pawl. There is a risk that: the torque at the pawl will pass through the decoupling window in a time shorter than the time T required to move the slider. In other words, if the torque C at the coupling claw is continued to be made_cTarget value C of torque at coupling pawl with first slope P1_{c _ target}Converge, the torque at the coupling jaws will be before the slider has finished movingThe target value is reached. In this case, the torque at the coupling pawl will increase until it becomes higher than the threshold value C_S1And the force at the coupling jaws will resist the movement of the slider, which may cause the disengagement operation to fail.

To solve this problem, the control system 11 comprises a module 16 for verifying the position of the slider, and a motor torque setpoint C for maintaining a torque at the coupling jaw for eliminating the torque at the coupling jaw with a second slope P2 having a dynamic gradient smaller than that of the first slope P1_{m_sp}Until the module 17 with the slide in the neutral position.

Thus, by means of the two phases of elimination of the torque at the coupling jaws of the invention, uncoupling can be ensured with a high level of robustness, avoiding potential uncoupling faults that would prevent the variation of the transmission ratio and create a noticeable disturbance felt by the vehicle driver.

For example, in the case of a transmission comprising two electric machines, it may be provided to disengage the coupling pawl of the internal combustion engine ratio, i.e. by operating the electric machine associated with the internal combustion engine, or to disengage the coupling pawl of the electric machine ratio, i.e. by operating the main electric machine.

In general, the invention relates to a clutchless transmission for a motor vehicle comprising an internal combustion engine, at least one electric machine, and at least one coupling system comprising, on the one hand, a coupling pawl fastened to an idle pinion, which is freely rotatably supported on a drive shaft of a wheel of the vehicle, and on the other hand, a coupling pawl fastened to a slide, which rotates with the motor shaft, which is connected directly or indirectly, through a fixed pinion, to a shaft of the internal combustion engine or to a shaft of the electric machine.

Fig. 3 depicts a flow chart of a method 50 for controlling a gearbox actuator of the transmission 1 of fig. 1.

During a first step 51, a motor rotor for eliminating the torque at the coupling jaws is calculated by applying the basic principle of dynamics to a "coupling jaw" systemMoment set point C_{m_sp}：

Wherein:

C_{m_sp}is the motor torque set point;

I_mis the radial inertia of the motor rotor;

r is the reduction ratio between the rotational speed of the motor and the rotational speed of the wheel; and is

Is the derivative of the rotational speed with respect to time in order to estimate the inertial component of the force at the coupling jaws; and is

C_{c _ target}Is a target value of torque at the coupling claw; the target value of the torque at the coupling claw is calculated in such a manner that the torque C at the coupling claw is obtained_cIs below a threshold value C_S1Exceeding the threshold may allow the coupling jaws to disengage. The target value of the torque at the coupling claw is then expressed at the motor by the reduction ratio.

During a second step 52, a motor torque setpoint C calculated for the motor for eliminating the torque at the coupling jaws is applied_{m_sp}To the motor.

In this way, the motor is commanded to reduce the level of torque it is providing following a curve of the linear reduction type with a first slope P1, illustrated in fig. 2, until a threshold C is reached_S1。

During step 53, torque C at the coupling jaws is coupled_cAnd a threshold value C_S1Making a comparison to check the torque C at the coupling jaws_cWhether or not it is less than or equal to the threshold value C_S1。

Torque at coupling jaw C_cLess than or equal to a threshold value C_S1Then, in step 54, the position set point P is sent_{_sp}To command the gearbox actuator to trigger the movement of the slide to disengage the coupling pawl in question by moving the slide towards the neutral positionAnd (4) disengaging.

Therefore, the uncoupling operation is performed in two steps, namely, a first step: calculating a torque set point to the motor by applying the basic principles of dynamics to cancel the sum of the torques at the coupling jaws; and a second step: once the torque at the coupling pawl is less than or equal to the threshold value, i.e. once the first step is completed, the position set point is used to command the gearbox actuator to move, which makes it possible to disengage the coupling pawl in question by moving the slider towards the neutral position.

However, the gearbox actuator requires a certain amount of time to move the slider and disengage the coupling pawl. There is a risk that: the torque at the coupling jaws will pass through the decoupling window in a time shorter than the time T required to move the slider. In other words, if the torque Cc at the coupling pawl is continued to be brought with the first slope P1 toward the target value C of the torque at the coupling pawl_{c _ target}Converging, the torque of the coupling jaws will reach this target value before the slide has finished moving. In this case, the torque at the coupling pawl will increase until it becomes higher than the threshold value C_S1And the force at the coupling jaws will resist the movement of the slider, which may cause the uncoupling operation to fail.

To overcome this problem, in step 54, the position of the slider is checked and in step 55, the motor torque setpoint C for eliminating the torque at the coupling pawl is maintained with a second slope P2 having a dynamic gradient smaller than that of the first slope P1_{m_sp}Until the slider is in the neutral position.

The invention is applicable to any clutchless transmission including: at least one coupling jaw of an idle pinion secured to a driveshaft of a driven wheel, at least one coupling jaw of a slide secured to a motor shaft, and a gearbox actuator configured to move the slide along a longitudinal axis of the driveshaft.

By means of the invention, uncoupling can be ensured at a high level of robustness and, therefore, potential uncoupling faults are avoided, which would prevent a change in the transmission ratio and create a noticeable disturbance felt by the vehicle driver. In addition, the present invention allows the pinion to be disengaged only upon control of the gearbox actuator.