Control device for a transmission, with driven coupling

Abstract

The present invention relates to a control device for a transmission, which comprises two motion transmission paths (TR1, TR2), one with a one-way coupling (10) and one with a driven coupling (12). The control device controls the driven coupling (12) to move into the open position depending on the speed of rotation of the secondary shaft of the transmission and its relative direction of rotation between the pinion (toothed wheel) and shaft which are connected by the one-way coupling (with respect to the direction of drive of the one-way coupling). In addition, the control device controls the driven coupling (12) to move into the closed position when the relative direction of rotation of the shaft is in the reverse direction to the direction of drive of the one-way coupling, so as to assist the performance of the transmission for recovering energy via the electric machine.

Description

[0001] TRANSMISSION CONTROL DEVICE WITH PILOT COUPLING

[0002] Technical field

[0003] The present invention relates to the field of transmission, in particular for systems (e.g. vehicles) driven by an electric machine.

[0004] In an electric vehicle, rotational speed and torque generated by an electric machine are transmitted to the vehicle's drive wheels. In addition, during vehicle deceleration or braking phases, it is possible to recover energy using the electric machine, which then functions as a generator (converting mechanical energy into electrical energy that can be stored in a battery).

[0005] Today, electric vehicle transmissions only use a reduction gear between the motor and the vehicle's wheel(s). This very simple solution limits the optimal use of the electric machine, and can generate high current draws, particularly for vehicles with a high weight / power ratio. This vehicle category includes, for example, small urban vehicles limited by law to 45 km / h (for example, two-seater vehicles that can be driven without a driving license). Since the authorized power is very low, the vehicle's dynamic performance is modest.

[0006] The same problems also arise in stationary applications of electrical machines, for which simple transmissions with a single reducer are not always suitable for dynamic variations in speed and torque.

[0007] Prior art

[0008] To address these issues, it may be considered to use transmissions designed for hybrid powertrains (with an electric machine and a thermal engine). For example, patent application FR 2962379 (US 2012-0031229) describes a speed transmission device for a motor vehicle, with two ratios, a high ratio and a low ratio. Although this transmission is well suited for a hybrid engine, this design is not suitable for the use of only an electric machine. Indeed, for this transmission device, the electric machine is directly connected to the engine axle shaft. Consequently, no transmission is provided to adapt the speed and torque output of the electric machine.Furthermore, depending on the gear train used, energy recovery by the electric machine is not always optimal: for example, when the centrifugal clutch is closed, energy recovery is reduced by the engine brake of the thermal engine. In addition, the transmission and its control are complex with two clutches: a piloted clutch and a centrifugal clutch.

[0009] Transmissions have also been developed for electric-only applications. For example, US Patent 11,384,817 describes a transmission for an electric vehicle. This transmission requires three driveshafts and three gear trains, a dog clutch system, and a clutch. The use of three driveshafts and three gear trains requires a large footprint. In addition, the use of a dog clutch system and a clutch makes the transmission and its control complex.

[0010] Summary of the invention

[0011] The present invention aims to control a transmission connected to an electric machine, in a simple manner, with good performance during energy recovery and by means of a compact transmission. For this, the present invention relates to a device for controlling a transmission, which comprises two gear trains, one with a one-way coupling and one with a piloted coupling. The control device controls the piloted coupling in the open position according to the rotation speed of the secondary shaft of the transmission, and its relative direction of rotation between pinion (toothed wheel) and shaft linked by the one-way coupling (relative to the driving direction of the one-way coupling).In addition, the control device controls the pilot-operated coupling in the closed position when the relative rotation direction of the shaft is in the opposite direction to the drive of the one-way coupling, so as to promote the transmission performance for energy recovery by the electric machine. Such control is simple, because only one component is controlled: the pilot-operated coupling. In addition, the transmission used is compact, as it requires only two shafts and two gear trains.

[0012] Furthermore, the invention relates to a method for controlling a transmission, and to an electric vehicle comprising such a control device.

[0013] The invention relates to a device for controlling a speed transmission, said transmission comprising a first transmission shaft connected to an electrical machine and carrying two primary toothed wheels cooperating with at least two secondary toothed wheels carried by a secondary transmission shaft, forming two movement transmission paths with different transmission ratios, one of said movement transmission paths comprising a unidirectional coupling, and the other of said movement transmission paths comprising a toothed wheel mounted freely in rotation on said secondary shaft or on said first transmission shaft and being connected to said shaft through a controlled coupling.Said control device is configured to control said piloted coupling in the open position when the rotational speed of the secondary shaft is lower than a speed threshold in the driving direction of said one-way coupling, and in that said control device is configured to control said piloted coupling in the closed position when the relative direction of rotation is in the opposite direction to the driving direction of said one-way coupling.

[0014] According to one embodiment, the control device is configured to control said piloted coupling in the open position further when the torque demand of said secondary shaft is greater than a torque threshold.

[0015] According to one implementation, said one-way coupling comprises a freewheel.

[0016] According to one aspect, said one-way coupling is arranged on one of said secondary gears of the motion transmission path having the shortest transmission ratio of said transmission.

[0017] Advantageously, said controlled coupling is arranged on one of said toothed wheels of the movement transmission path having the longest transmission ratio of said transmission.

[0018] According to one embodiment option, said piloted coupling is controlled in the closed position when the rotational speed of the secondary transmission shaft is greater than said speed threshold, or when the relative direction of rotation of the shaft on which said one-way coupling is mounted is in the opposite direction to the driving direction of said one-way coupling.

[0019] According to one embodiment, each motion transmission path is formed by a gear train.

[0020] Alternatively, the transmission comprises a self-closed band connecting the toothed wheels of each motion transmission path, preferably said self-closed band is a chain or a belt.

[0021] Furthermore, the invention relates to a method for controlling a speed transmission, said transmission comprising a first transmission shaft connected to an electrical machine and carrying two primary toothed wheels cooperating with at least two secondary toothed wheels carried by a secondary transmission shaft forming two motion transmission paths with different transmission ratios, one of said motion transmission paths comprising a one-way coupling, and the other of said motion transmission paths comprising a toothed wheel mounted freely in rotation on said secondary shaft or on said first transmission shaft and being connected to said shaft through a controlled coupling. For this method, the following steps are implemented: a.When the rotational speed of the secondary shaft is lower than a speed threshold in the driving direction of said one-way coupling, said piloted coupling is opened; b. When the relative direction of rotation is in the opposite direction of rotation to the driving direction of said one-way coupling, said piloted coupling is closed.

[0022] According to one implementation, said controlled coupling is further opened when the requested torque of said secondary shaft is greater than a torque threshold.

[0023] According to one embodiment, said controlled coupling is closed when the rotational speed of the output shaft is greater than said speed threshold in the driving direction of said one-way coupling.

[0024] Furthermore, the invention relates to an electric vehicle, in particular a motor vehicle, comprising a transmission, said transmission comprising a first transmission shaft connected to an electric machine and carrying two primary toothed wheels cooperating with at least two secondary toothed wheels carried by a secondary transmission shaft forming two gear trains with different transmission ratios, one of said gear trains comprising a unidirectional coupling, and the other of said gear trains comprising a toothed wheel mounted to rotate freely on the secondary shaft or on said first transmission shaft and being connected to said shaft through a controlled coupling. Said vehicle comprises a control device according to one of the preceding characteristics.

[0025] Other characteristics and advantages of the device and method according to the invention will appear on reading the following description of non-limiting examples of embodiments, with reference to the figures appended and described below. List of figures

[0026] Figure 1 illustrates a transmission adapted for the control device according to a first variant embodiment of the invention.

[0027] Figure 2 illustrates a transmission adapted for the control device according to a second variant embodiment of the invention.

[0028] Figure 3 illustrates the different control phases as a function of the torque and rotation speed according to a first embodiment of the invention.

[0029] Figure 4 illustrates the different control phases as a function of the torque and rotation speed according to a second embodiment of the invention.

[0030] Description of the embodiments

[0031] The present application relates to a device and a method for controlling a transmission connected to an electric machine which can operate in electric motor mode or in energy generator mode, the electric machine being powered by an electric battery. The transmission, also called a gearbox, comprises:

[0032] A first transmission shaft connected to the electric machine, the first transmission shaft carries two gear wheels, called primary gear wheels, and A second transmission shaft, also called secondary transmission shaft or output shaft, the second transmission shaft carries two gear wheels, called secondary gear wheels.

[0033] Each primary gear wheel cooperates with a secondary gear wheel, so as to form a motion transmission path. Thus, the transmission comprises two motion transmission paths. The two motion transmission paths have different transmission ratios. It is recalled that the transmission ratio is the ratio of the rotational speed of the secondary transmission shaft to the rotational speed of the first transmission shaft. This transmission ratio is proportional to the ratio of the number of teeth on the primary gear wheel to the number of teeth on the secondary gear wheel. (If we take pulley and belt type drive means, the ratio can be adjusted by choosing, in particular, different diameters of the input and output pulleys). Advantageously, each motion transmission path can be formed by a gear train; in other words, two gear wheels cooperating directly.Alternatively, each transmission path may comprise a self-enclosed band connecting the toothed wheels of each motion transmission path, preferably said self-enclosed band may be a chain or a belt.

[0034] In the remainder of the application, only gear trains are described. However, all embodiments are compatible with the self-enclosed belt or chain type band connecting the toothed wheels.

[0035] Preferably, the transmission may comprise only two shafts: the first transmission shaft and the second transmission shaft, and may comprise only two transmission ratios. Thus, the transmission remains compact and simple to control, while allowing control of the speed and torque of the output shaft adapted to the desired applications (e.g., motor vehicle).

[0036] In addition, one of the gear trains includes a one-way coupling, also called a one-way clutch. Thus, one of the gear wheels is connected to its shaft (first transmission shaft or second transmission shaft) by a one-way coupling. Such a coupling makes it possible to secure the gear wheel and its shaft in one direction of relative rotation, and in the other direction of rotation the gear wheel and the shaft are separated and can rotate relative to each other. Such a one-way coupling is not controllable: the securing and the disengagement are carried out automatically. According to an exemplary embodiment, the one-way coupling can be a freewheel arranged between the bearing of the gear wheel and the shaft. In addition, the one-way coupling (the freewheel) is disengaged when there is a speed differential between the shaft and the gear wheel.

[0037] In addition, the other gear train comprises a toothed wheel mounted loosely in rotation on its shaft (first transmission shaft or second transmission shaft), this wheel being connected to its shaft by means of a piloted coupling, also called a piloted disengageable coupling. Such a piloted coupling allows simple control of the transmission: the closing of the piloted coupling ensures the drive of the toothed wheel, and its opening allows a relative rotation between the toothed wheel and its shaft. The control of the piloted coupling can in particular be electric, hydraulic or pneumatic. By way of non-limiting example, the piloted coupling can be a single-disc or multi-disc clutch.When the pilot-operated coupling is closed, there is a speed differential at the one-way coupling (difference in rotational speed between the gear wheel and the rotational speed of the shaft connected by the one-way coupling), which is then disengaged.

[0038] In the remainder of the description, the first gear train is the gear train which includes the one-way coupling, and the second gear train is the gear train which includes the piloted coupling.

[0039] According to the invention, the control device controls the piloted clutch in the open position or in the closed position, in particular:

[0040] In the open position, when the rotational speed of the output shaft is lower than a speed threshold, and when the direction of rotation of the shaft on which the one-way coupling is mounted is in the driving direction of the one-way coupling, thus at low rotational speed the movement is transmitted between the first transmission shaft and the second transmission shaft by the first gear train,

[0041] In the closed position, when the relative direction of rotation of the shaft on which the one-way coupling is mounted is in the opposite direction to the driving direction of the one-way coupling, thus the movement is transmitted between the second transmission shaft and the first transmission shaft by the second gear train for energy recovery (by means of the electric machine in generator mode, for example during braking or deceleration) or for reverse gear or for high speeds of the secondary shaft.

[0042] Advantageously, the first gear train corresponds to the shortest transmission ratio of the transmission, and the second gear train to the longest transmission ratio of the transmission. The shortest transmission ratio is the one with the lowest transmission ratio, and conversely the longest transmission ratio is the one with the highest transmission ratio. Thus, the longest ratio is implemented in particular for energy recovery, and the short ratio is implemented for low rotation speeds. Preferably, the ratio between the second ratio and the first ratio may be between 0.1 and 0.9, in particular between 0.3 and 0.8.

[0043] The rotational speed threshold corresponds to the maximum speed of the electric machine on the ratio of the first gear train. Thus, the threshold depends on the design of the electric machine and the transmission ratio.

[0044] According to one embodiment of the invention, the control device can furthermore control the piloted coupling in the open position when the torque demand of the second transmission shaft is greater than a torque threshold, which can correspond to the maximum torque available on the second gear train, preferably with the long ratio (highest transmission ratio) or a predefined torque lower than the maximum torque available on the second gear train, preferably with the long ratio. Thus, for the control device controls the piloted coupling in the open position when the following two conditions are verified: the torque is greater than a torque threshold and the rotation speed is less than a speed threshold. In this way, a "boost" (additional torque demand) is available for the application concerned.

[0045] According to one implementation of the invention, the control device can control the piloted coupling in the closed position when the rotational speed of the secondary transmission shaft is greater than the speed threshold. Thus, the second gear train is engaged when the rotational speed is greater than the speed threshold.

[0046] Advantageously, the one-way coupling device can be arranged on the secondary gear wheel of the first gear train. Alternatively, the one-way coupling device can be arranged on the primary gear wheel of the first gear train.

[0047] According to one aspect of the invention, the piloted coupling can be arranged on the primary gear wheel of the second gear train. Alternatively, the piloted coupling can be arranged on the secondary gear wheel of the second gear train.

[0048] According to one embodiment, the output shaft of the transmission can be connected, directly or indirectly, to the axle shaft of an electric vehicle.

[0049] Advantageously, the transmission may be provided with a rotational speed sensor for the second transmission shaft, the sensor indicating the rotational speed of the second transmission shaft for the control device. This configuration is simple to implement. Alternatively, the control system may comprise means for estimating the rotational speed of the second transmission shaft, in particular an observer. This configuration limits the instrumentation of the transmission.

[0050] In addition, the invention relates to a method of controlling a speed transmission. The controlled speed transmission is in accordance with any of the variants or combinations of variants described above.

[0051] Advantageously, the control device according to the invention can implement the control method according to the invention. For example, the control device can comprise a control unit which controls the controlled coupling by implementing the steps of the method according to the invention.

[0052] The following steps are implemented for the control process:

[0053] When the rotational speed of the second transmission shaft is lower than a speed threshold, and when the relative direction of rotation of the shaft on which the one-way coupling is arranged is in the driving direction of the one-way coupling, the controlled coupling is opened, thus, the transmission of movement between the first transmission shaft and the second transmission shaft is implemented by the first gear train,

[0054] When the relative direction of rotation of the shaft on which the one-way coupling is arranged is in the opposite direction to the drive direction of the one-way coupling, the piloted coupling is closed, thus the energy recovery on the electric machine and the reverse gear is carried out by the second gear train, preferably corresponding to the long ratio.

[0055] Advantageously, the first gear train corresponds to the shortest transmission ratio of the transmission, and the second gear train to the longest transmission ratio of the transmission. The shortest transmission ratio is the one with the lowest transmission ratio, and conversely, the longest transmission ratio is the one with the highest transmission ratio. Thus, the longest ratio is implemented for energy recovery, reverse gear and high rotational speeds, and the shortest ratio is implemented for low rotational speeds.

[0056] The rotation speed threshold corresponds to a speed close (for example 90, 95, 98%) to the maximum speed of the electric machine on the ratio of the first gear train.

[0057] According to one embodiment of the invention, the control method can furthermore control the piloted coupling in the open position when the torque requested on the second transmission shaft is greater than a torque threshold which can correspond to the maximum torque available on the second gear train (preferably corresponding to the long ratio), or to a predefined torque lower than the maximum torque available on the second gear train (preferably corresponding to the long ratio). Thus, for the control method, the piloted coupling is controlled in the open position when the following two conditions are satisfied: torque request greater than a torque threshold and rotation speed less than a speed threshold. In this way, a "boost" (additional torque request) is available for the application concerned.According to one implementation of the invention, for the control method, the piloted coupling can be controlled in the closed position when the rotational speed of the secondary transmission shaft is greater than the speed threshold. Thus, the second gear train is engaged when the rotational speed is greater than the speed threshold.

[0058] According to one implementation of the invention, the method may comprise a step of measuring the rotational speed of the second transmission shaft, in particular by means of a rotational speed sensor, in order to determine its rotational speed to compare it with the corresponding threshold. This solution is simple to implement. Alternatively, the method may comprise a step of estimating the rotational speed of the second transmission shaft. This configuration limits the instrumentation of the transmission.

[0059] Figure 1 illustrates, schematically and in a non-limiting manner, a device for controlling a transmission according to a first embodiment of the invention. The control device comprises an electrical machine 1 connected to a transmission 2. In particular, the electrical machine 1 is connected to the first transmission shaft 3 of the transmission 2. The first transmission shaft 3 carries two primary gear wheels 4 and 5. The transmission 2 further comprises a second transmission shaft 8 carrying two secondary gear wheels 6 and 7. The second transmission shaft is the output of the transmission 2. The primary gear wheel 5 cooperates with the secondary gear wheel 6 to form a first gear train TR1, forming a short ratio (lowest transmission ratio). The primary gear wheel 4 cooperates with the secondary gear wheel 7 to form a second gear train TR2, forming a long ratio (highest transmission ratio).

[0060] The first gear train TR1 comprises a one-way coupling. For the illustrated embodiment, this one-way coupling is formed by a freewheel 10 arranged between the bearing 9 of the secondary gear wheel 6 and the secondary transmission shaft 8.

[0061] The second gear train TR2 comprises a controlled coupling 12. For the illustrated embodiment, the controlled coupling is arranged between the secondary transmission shaft 8 and the secondary gear wheel 7. Closing the controlled coupling 12 makes it possible to secure the secondary gear wheel 7 and the secondary transmission shaft 8.

[0062] The control device further comprises a control unit 13 controlling the opening and closing of the piloted coupling 12.

[0063] Figure 2 illustrates, schematically and in a non-limiting manner, a device for controlling a transmission according to a second embodiment of the invention. The control device comprises an electrical machine 1 connected to a transmission 2. In particular, the electrical machine 1 is connected to the first transmission shaft 3 of the transmission 2. The first transmission shaft 3 carries two primary gear wheels 4 and 5. The transmission 2 further comprises a second transmission shaft 8 carrying two secondary gear wheels 6 and 7. The second transmission shaft is the output of the transmission 2. The primary gear wheel 5 cooperates with the secondary gear wheel 6 to form a first gear train TR1, forming a short ratio (lowest transmission ratio). The primary gear wheel 4 cooperates with the secondary gear wheel 7 to form a second gear train TR2, forming a long ratio (highest transmission ratio).

[0064] The first gear train TR1 comprises a one-way coupling. For the illustrated embodiment, this one-way coupling is formed by a freewheel 10 arranged between the bearing 9 of the secondary gear wheel 6 and the secondary transmission shaft 8. Alternatively, the one-way coupling is formed by a freewheel arranged between the bearing of the first gear wheel 5.

[0065] The second gear train TR2 comprises a piloted coupling 12. For the illustrated embodiment, the piloted coupling is arranged between the first transmission shaft 3 and the first gear wheel 4. Closing the piloted coupling 12 makes it possible to secure the first gear wheel 4 and the first transmission shaft 3.

[0066] The control device further comprises a control unit 13 controlling the opening and closing of the piloted coupling 12.

[0067] Figures 3 and 4 illustrate the control according to two variants of the invention. Figures 3 and 4 are graphs of the torque C of the output shaft as a function of the rotation speed V of the output shaft. On this graph, by convention, when the torque is negative, this implies that the relative direction of rotation of the shaft on which the one-way coupling is arranged is in the opposite direction to the drive direction of the one-way coupling (which corresponds to reverse gear or energy recovery by the electric machine). In addition, the torque is represented as a relative value compared to the maximum torque of the speed considered. On these graphs, several control zones of the electric machine are represented with different commands.

[0068] For the first variant of Figure 3:

[0069] In the control zone Z1, for which the torque is positive, and the rotational speed of the output shaft is lower than a rotational speed threshold Vs, the device and the method according to the invention control the opening of the piloted coupling, the transmission is then ensured by the first gear train with a short ratio, In the control zone Z2, for which the torque is positive, and the rotational speed of the output shaft is higher than the rotational speed threshold Vs, the device and the method according to the invention control the closing of the piloted coupling, the transmission is then ensured by the second gear train with a long ratio, and

[0070] In the control zone Z3, for which the torque is negative, the device and method according to the invention control the closing of the controlled coupling for reverse gear and the recovery of energy by the electric machine, the transmission then being ensured by the second gear train with a long ratio.

[0071] For the second variant of Figure 4:

[0072] In the control zone ZT, for which the torque is positive, and the rotational speed of the output shaft is lower than a rotational speed threshold Vs, and the torque demand is higher than a torque threshold Cs, the device and the method according to the invention control the opening of the piloted coupling, the transmission is then ensured by the first gear train with a short ratio,

[0073] In the control zone Z2', for which the torque is positive, and the rotation speed is lower than the rotation speed threshold Vs and the torque is lower than the torque threshold Cs, or the rotation speed is higher than the rotation speed threshold Vs regardless of the torque requested, the device and the method according to the invention control the closing of the piloted coupling, the transmission is then ensured by the second gear train with a long ratio, and In the control zone Z3, for which the torque is negative, the device and the method according to the invention control the closing of the piloted coupling for reverse gear and energy recovery by the electric machine, the transmission then being ensured by the second gear train with a long ratio.

[0074] Furthermore, the invention relates to an electric vehicle, in particular a motor vehicle (which may in particular comprise two, three or four wheels), which comprises an electric machine, a speed transmission according to any of the variants or combinations of variants described above, as well as a control device according to any of the variants or combinations of variants described above. The control device and method are particularly suitable for use within an electric vehicle, in particular a small urban vehicle, for example a two-seater motor vehicle, which can be driven without a driving license.Indeed, the device and the control method according to the invention make it possible to move the vehicle either forward or reverse over the entire range of use of the electric machine, and make it possible to maximize the recovery of electrical energy during the deceleration and / or braking phases. In addition, the invention allows optimal use of the electric machine, without generating high current draws, particularly for vehicles where the weight / power ratio is high.

[0075] Alternatively, the device and the control method are also suitable for stationary applications requiring an electric drive, for example for household appliances, industrial machines, etc.

Claims

Claims 1. Device for controlling a speed transmission (2), said transmission comprising a first transmission shaft (3) connected to an electrical machine (1) and carrying two primary toothed wheels (4; 5) cooperating with at least two secondary toothed wheels (6; 7) carried by a secondary transmission shaft (8), forming two motion transmission paths (TR1, TR2) with different transmission ratios, one of said motion transmission paths (TR1, TR2) comprising a unidirectional coupling (10), and the other of said motion transmission paths (TR1, TR2) comprising a toothed wheel mounted freely in rotation on said secondary shaft (8) or on said first transmission shaft (3) and being connected to said shaft through a controlled coupling (12),characterized in that said control device is configured to control said piloted coupling (12) in the open position when the rotational speed of the secondary shaft (8) is lower than a speed threshold in the driving direction of said unidirectional coupling (10), and in that said control device is configured to control said piloted coupling (12) in the closed position when the relative direction of rotation is in the opposite direction to the driving direction of said unidirectional coupling (10)., 2. Control device according to claim 1, wherein the control device is configured to control said piloted coupling (12) in the open position further when the torque demand of said secondary shaft is greater than a torque threshold.

3. Control device according to one of the preceding claims, wherein said one-way coupling comprises a freewheel (10).

4. Control device according to one of the preceding claims, wherein said unidirectional coupling (10) is arranged on one of said secondary toothed wheels (6, 7) of the motion transmission path (TR1, TR2) having the shortest transmission ratio of said transmission.

5. Control device according to one of the preceding claims, wherein said piloted coupling (12) is arranged on one of said toothed wheels of the movement transmission path (TR1, TR2) having the longest transmission ratio of said transmission.

6. Device according to one of the preceding claims, in which said piloted coupling (12) is controlled in the closed position when the rotation speed of the secondary transmission shaft is greater than said speed threshold, or when the direction relative rotation of the shaft on which said one-way coupling is mounted is in the opposite direction to the driving direction of said one-way coupling.

7. Device according to one of the preceding claims, in which each movement transmission path (TR1, TR2) is formed by a gear train.

8. Device according to one of claims 1 to 6, in which the transmission comprises a band closed on itself connecting the toothed wheels of each movement transmission path (TR1, TR2), preferably said band closed on itself is a chain or a belt.

9. Device according to one of the preceding claims, characterized in that the control of the piloted coupling (12) is electric, hydraulic or pneumatic.

10. Device according to one of the preceding claims, characterized in that the controlled coupling (12) is a single-disc or multi-disc clutch.

11. Method for controlling a speed transmission, said transmission comprising a first transmission shaft (3) connected to an electrical machine (1) and carrying two primary toothed wheels (4, 5) cooperating with at least two secondary toothed wheels (6, 7) carried by a secondary transmission shaft (8) forming two motion transmission paths (TR1, TR2) with different transmission ratios, one of said motion transmission paths (TR1, TR2) comprising a unidirectional coupling (10), and the other of said motion transmission paths (TR1, TR2) comprising a toothed wheel mounted freely in rotation on said secondary shaft (8) or on said first transmission shaft (3) and being connected to said shaft through a piloted coupling (12), characterized in that the following steps are implemented: a.When the rotational speed of the secondary shaft (8) is lower than a speed threshold in the driving direction of said one-way coupling (10), said piloted coupling (12) is opened; b. When the relative direction of rotation is in the opposite direction of rotation to the driving direction of said one-way coupling (10), said piloted coupling (12) is closed.

12. Control method according to the preceding claim, in which said piloted coupling (12) is further opened when the requested torque of said secondary shaft (8) is greater than a torque threshold.

13. Control method according to one of claims 11 or 12, in which said piloted coupling (12) is closed when the rotation speed of the output shaft is greater than said speed threshold in the driving direction of said one-way coupling (10).

14. Electric vehicle, in particular motor vehicle, comprising a transmission (2), said transmission comprising a first transmission shaft (3) connected to an electrical machine (1) and carrying two primary toothed wheels (4, 5) cooperating with at least two secondary toothed wheels (6, 7) carried by a secondary transmission shaft (8) forming two motion transmission paths (TR1, TR2) with different transmission ratios, one of said motion transmission paths (TR1, TR2) comprising a unidirectional coupling (10), and the other of said motion transmission paths (TR1, TR2) comprising a toothed wheel mounted loosely in rotation on the secondary shaft (8) or on said first shaft (3) transmission and being connected to said shaft through a piloted coupling, characterized in that said vehicle comprises a control device according to one of claims 1 to 10.

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