Drive shaft coupling system

Abstract

Title of the invention: Transmission shaft coupling system The present invention relates to a transmission shaft coupling system comprising: - a driving shaft (2) including a first drive spline; - a driven shaft (3) coaxial with the driving shaft including a second drive spline; - a dog clutch sleeve (30) including at least a first connecting spline adapted to drive the driving shaft in rotation about a first axis of rotation (X) and a second connecting spline adapted to drive the driven shaft in rotation;- an actuation device (10) comprising an electric motor kinematically linked to a speed reduction device, an output shaft (40) of the speed reduction device rotating about a second axis of rotation (Y), an interface component (20) disposed at the end of the output shaft and arranged to pivot within the dog clutch sleeve, and an elastic damping means (50) acting in torsion about the second axis of rotation (Y) is disposed between the output shaft (40) and the interface component (20) of the actuation device. Abstract figure: Figure 1;

Description

Title of the invention: Transmission shaft coupling system

[0001] The present invention relates to the field of transmission shaft coupling systems.

[0002] The drive shaft coupling system is, for example, integrated into an electric transmission of a motor vehicle, which comprises an electric machine and an associated speed reducer, the coupling system being placed, in particular, between the output of the speed reducer and the wheel of the vehicle. The motor vehicle may be electric or hybrid.

[0003] In the example of a motor vehicle with a hybrid transmission comprising an internal combustion engine and an electric transmission, such coupling systems can be used to connect the electric transmission to the rear wheels of the vehicle when its use becomes necessary to supplement the internal combustion engine, which provides torque and power to the front wheels. Such a driveshaft coupling system is known from document WO2016 / 096769 AL

[0004] In this document, the transmission shaft coupling system is interposed between a transmission drive shaft comprising a first internal spline and a transmission driven shaft coaxial to the drive shaft comprising a second external spline.

[0005] The coupling system also includes a double-spline connector suitable for connecting the driving shaft to the driven shaft when the use of electric transmission becomes necessary. The double-spline connector is mounted longitudinally on the driven transmission shaft. The connector is driven along the axis of rotation of the driven transmission shaft by means of an actuation device comprising an electric motor associated with a speed reduction device, for example, an epicyclic gear train.

[0006] For this purpose, an internal surface of the double-groove connector is provided with an internal groove that mates with the external groove of the driven transmission shaft and an external groove that is able to mate with the internal groove of the driving transmission shaft.

[0007] When the coupling system is in an uncoupled position, the outer spline of the connector is not engaged in the first inner spline of the driving shaft. The driving shaft and the connector have different rotational speeds. In order to engage the connection between the driving and driven transmission shafts, the electric motor of the actuation device is used to Rotating an eccentric control rod within an annular groove in the double-groove connector. Rotating the eccentric control rod around a central axis of the epicyclic gear train allows the connector to be moved longitudinally.

[0008] When the coupling system is in a coupling position, the rotational speeds of the driven shaft, the driving shaft and the double-groove connector are identical.

[0009] It is therefore understood that the engagement of the teeth of the connector spline within the internal spline of the driving shaft can only occur under certain conditions. The geometry of the teeth is a key factor in facilitating insertion. The speed differential during engagement must also be small to allow the insertion of the teeth of the connector spline. To achieve this, the electric motor of the transmission is used to adjust the rotational speed of the driving shaft as close as possible to the rotational speed of the driven shaft. When the set speed is reached, the teeth of the connector spline are inserted by axially moving the connector.

[0010] However, it is possible that the insertion attempt may fail simply because the available time for the internal and external splines to be fully aligned is too short. The teeth of the connector spline may then strike the top of the drive shaft spline.

[0011] During these failed insertion attempts, shocks can occur at the splines, which are transmitted within the eccentric control rod of the actuating device. Repeated shocks can propagate along the central axis of the actuating device and travel up into the speed reduction device in the form of a temporary overtorque. This shock transmission can cause damage to the epicyclic gear train of the actuating device, which includes teeth not designed to withstand such a temporary overtorque.

[0012] The present invention aims to overcome these drawbacks by proposing a transmission shaft coupling system in which the shocks associated with a failure of tooth engagement are absorbed outside the speed reduction device of the actuation device.

[0013] The main object of the present invention is therefore a transmission shaft coupling system comprising:

[0014] - a transmission drive shaft comprising a first spline training;

[0015] - a coaxial transmission driven shaft to the driving shaft comprising a second drive groove;

[0016] - a dog clutch sleeve comprising at least one first groove of connection capable of driving the driving shaft in rotation along a first axis of rotation and a second spline of connection capable of driving the driven shaft in rotation;

[0017] - an actuation device comprising a kinematically linked electric motor to a speed reduction device, an output shaft of the speed reduction device rotating about a second axis of rotation, an interface component disposed at the end of the output shaft and arranged to pivot within a receiving housing formed in the dog clutch sleeve, the dog clutch sleeve being able to move axially along the first axis of rotation between a first extreme disengagement position and a second extreme engagement position when the output shaft pivots through a predetermined angular sector,

[0018] The transmission shaft coupling system is remarkable in that an elastic damping means acting in torsion along the second axis of rotation is disposed between the output shaft and the interface component of the actuation device.

[0019] This transmission shaft coupling system architecture prevents damage to the speed reduction device of the actuation device by dampening the shock generated by the teeth of the spline of the dog clutch sleeve when they strike the top of the spline of the driving or driven shaft. This significantly reduces the temporary overtorque that could build up within the teeth of the speed reduction device when the insertion attempt is aborted.

[0020] The actuation device remains compact because the elastic damping means is offset outside the speed reduction device.

[0021] Preferably, the interface component is angularly movable relative to the output shaft.

[0022] Advantageously, the predetermined angular sector is between 20° and 180° allowing the dog clutch sleeve to move from the first extreme disengagement position, in which one of the first or second connecting splines is disengaged from either the first drive spline of the driving shaft or the second drive spline of the driven shaft, to the second extreme coupling position, in which the first and second connecting splines are engaged respectively in the first drive spline of the driving shaft and the second drive spline of the driven shaft.

[0023] Preferably, the elastic damping means comprises a torsion spring that allows angular displacement of the interface component relative to the output shaft by an angle between 5° and 20°. The torsion spring is a A reliable mechanical component whose angular stiffness can easily adapt to the constraints of the actuation device. The rotation of the interface component is achieved by the deformation of the torsion spring.

[0024] Advantageously, the angular stiffness of the elastic damping means is between 0.01 Nm / ° and 1 Nm / °, for example the angular stiffness is equal to 0.1 Nm / °.

[0025] According to one aspect of the invention, the torsion spring applies a preload torque between the output shaft and the interface component, the preload torque value being between 0.5 Nm and 5 Nm, the interface component being pressed directly or indirectly against the output shaft when the actuating device is inactive. In this way, the elastic damping means is activated only when the attempt to insert the teeth of the spline of the dog clutch sleeve into the spline of the driving shaft is aborted. It is not necessary to place an axial position sensor on the dog clutch sleeve to monitor the engagement of the splines. Only the angular sensor of the actuating device is necessary to manage the engagement of the splines.

[0026] Preferably, the torsion spring comprises a first end inserted into the output shaft and a second end inserted into the interface component.

[0027] Advantageously, the receiving housing of the dog clutch sleeve is in the form of a groove composed of two lateral rims and a cylindrical bottom and receives the interface component of the output shaft.

[0028] According to one aspect of the invention, the torsion spring is a blade wound around the second axis of rotation made from a flat wire.

[0029] According to one example, the torsion spring may include a first end inserted into a support slot formed in the output shaft and a second end inserted into a hollow housing of the interface component.

[0030] Preferably, the output shaft includes at least one first protrusion disposed on the end of the shaft, the interface component includes a hollow housing which surrounds the first protrusion, the hollow housing including two stop faces which limit the angular deflection with respect to the first protrusion of the output shaft.

[0031] Advantageously, the output shaft includes a second cylindrical protrusion with an axis concentric to the second axis of rotation and disposed on the end of the first protrusion, the interface component pivoting around the second protrusion by means of a bore which opens into the hollow housing.

[0032] Preferably, the elastic damping means includes an axial stop washer fixed on the second protrusion.

[0033] According to this aspect of the invention, the elastic damping means in the form of a rolled blade has a reduced footprint, which promotes the compactness of the actuation device.

[0034] According to another aspect of the invention, the torsion spring is a helical torsion spring with round wire.

[0035] Preferably, the helical torsion spring with round wire comprises a first end inserted into a cylindrical bore of the output shaft and a second end inserted into a cylindrical bore or slot of the interface component. According to this aspect of the invention, the geometry of the output shaft and / or the interface component remains simple, and machining time is reduced.

[0036] Preferably, one end of the torsion spring, chosen from the first end or the second end, has a 90° bend, the actuating cam 20 being held axially on the output shaft by the bent end of the torsion spring.

[0037] According to another aspect of the invention, the torsion spring is a flat wire helical torsion spring.

[0038] According to another aspect of the invention, the elastic damping means is formed directly by the interface component, the interface component being, for example, a blade wound around the second axis of rotation made from a flat wire, the wound blade comprising at least three actuation faces formed in the form of a portion of a cylinder, and the three centers of the portion of a cylinder forming an isosceles triangle. Advantageously, the interface component directly performs the additional damping function. This aspect of the invention makes it possible to eliminate a component, which contributes to reducing the manufacturing cost of the transmission shaft coupling system.

[0039] Advantageously, the wound blade includes a first end inserted into a groove in the output shaft.

[0040] According to another aspect of the invention, the interface component is an eccentric actuating rod with respect to the second axis of rotation of the actuating device, the eccentric actuating rod being a cylindrical component which is inserted into the receiving housing of the dog clutch sleeve.

[0041] The eccentric actuating rod can be a rolling bearing, for example a ball bearing or a roller bearing.

[0042] The eccentric actuating rod can be held in position by one end of a helical torsion spring with round wire.

[0043] According to one embodiment of the invention, the dog clutch sleeve comprises at least one first internal connecting groove arranged to drive the driving shaft in rotation and a second internal connecting groove arranged to drive in rotation of the driven shaft, the first and second internal splines being engaged respectively in a first external transmission spline of the driving shaft and a second external transmission spline of the driven shaft when the dog clutch sleeve is in the second extreme coupling position.

[0044] According to another embodiment of the invention, the dog clutch sleeve comprises at least a first external connecting groove arranged to drive the driving shaft in rotation and a second internal connecting groove arranged to drive the driven shaft in rotation, the first and second internal grooves being engaged respectively in a first internal transmission groove of the driving shaft and a second external transmission groove of the driven shaft when the dog clutch sleeve is in the second extreme coupling position.

[0045] According to one aspect of the invention, the interface component is an actuating cam pivoting about the second axis of rotation of the actuating device. The actuating cam comprises three actuating faces formed in the form of cylindrical segments, and the three centers of these cylindrical segments form an isosceles triangle. The geometry of the contact areas of the actuating cam uses large-diameter cylindrical segments, thereby reducing the contact pressure with the clutch sleeve.

[0046] For example, the principal vertex of the isosceles triangle can be coincident with the second axis of rotation of the output shaft.

[0047] Preferably, the actuating cam may have a symmetrical actuation profile whose axis of symmetry passes through the bisector of the isosceles triangle, the bisector of the isosceles triangle corresponding to the midpoint of the second angular sector. The actuating cam thus has a symmetrical profile passing through the second axis of rotation of the output shaft.

[0048] Preferably, the interface component of the actuation device is an actuation cam arranged to pivot along three adjacent angular sectors, a first angular sector, a second angular sector which is adjacent to the first angular sector, a third angular sector which is adjacent to the second angular sector of actuation, the sum of the three angular sectors corresponding to the predetermined angular sector,

[0049] and wherein the dog clutch sleeve moves axially between two extreme positions when the output shaft pivots through the entire second angular sector,

[0050] the dog clutch sleeve remaining axially immobile in a first extreme position when the rotation of the output shaft is in the first angular sector,

[0051] and the dog clutch sleeve remaining axially fixed in a second extreme position when the output shaft rotation is within the third angular sector. This actuation device, thanks in particular to the first and third angular sectors, allows for two stable extreme actuation positions because an angular variation of a few degrees on the output shaft does not cause any displacement of the receiving part. Since the two extreme actuation positions are stable, it is possible to cut off the power supply to the actuation device, thereby reducing the vehicle's electrical consumption.

[0052] The angle value of the second angular sector is strictly less than 180°. Thus, the angular travel of the output shaft is reduced, which has the effect of reducing the actuation time.

[0053] The actuating cam may have two contact areas arranged to bear against parallel surfaces of the receiving housing; the contact width along the first axis of rotation separating the two contact areas is constant over the predetermined angular sector of rotation of the output shaft. The actuation accuracy is thus improved.

[0054] Advantageously, an operating clearance can be defined between the support width The operating clearance of the actuating cam and the axial distance separating the two parallel surfaces of the intermediate sleeve groove along the first axis of rotation ensures a constant operating clearance across all three angular sectors of rotation of the output shaft. This operating clearance is on the order of 0.1 mm to 0.6 mm, thus improving actuation accuracy.

[0055] The actuation device for the transmission shaft coupling system according to the invention may have one or more of the characteristics described below, either combined or taken independently of each other:

[0056] - the actuation device is mounted on a fixing housing;

[0057] - the angle value of the first angular sector is greater than 3°;

[0058] - the angle value of the second angular sector is between 20° and 174°;

[0059] - the angle value of the third angular sector is greater than 3°;

[0060] - the angle value of the first angular sector is identical to the angle value of the third angular sector;

[0061] - the angle value of the first angular sector is different from the angle value of the third angular sector;

[0062] - the angle value of the second angular sector is greater than the angle value of the first angular sector;

[0063] - the angle value of the second angular sector is greater than the angle value of the third angular sector;

[0064] - the interface component is separate from the device's output tree actuation;

[0065] - the interface component pivots relative to the output shaft of the device actuation along the second axis of rotation;

[0066] - the interface component deforms relative to the output shaft of the device actuation along the second axis of rotation.

[0067] The invention also relates to a motor vehicle with hybrid or electric transmission comprising a transmission shaft coupling system as previously mentioned.

[0068] Other features, details and advantages of the invention will become clearer upon reading the following description on the one hand, and the illustrative and non-limiting examples of embodiments given with reference to the accompanying drawings on the other hand, in which:

[0069] [Fig-1] is a cross-sectional view of a transmission shaft coupling system according to a first embodiment of the invention;

[0070] [Fig.2] is a top view of the actuation cam of the transmission shaft coupling system of [Fig.1];

[0071] [Fig.3] is a simplified view of the interface end of the output shaft of the actuation device of the [Fig.1];

[0072] [Fig.4] is an isometric view of the output shaft of the transmission shaft coupling system according to the first embodiment of the invention of [Fig.1];

[0073] [Fig.5] is a cross-sectional view of the output shaft according to the first embodiment of the invention of [Fig.1];

[0074] [Fig.6] is an isometric view of the output shaft of the transmission shaft coupling system according to a second embodiment of the invention;

[0075] [Fig.7] is a cross-sectional view of the output shaft according to the second embodiment of the invention of [Fig.6];

[0076] [Fig.8] is an isometric view of the output shaft of the transmission shaft coupling system according to a third embodiment of the invention;

[0077] [Fig.9] is a cross-sectional view of the output shaft according to the third embodiment of the invention of [Fig.8];

[0078] [Fig. 10] is an isometric view of the output shaft of the transmission shaft coupling system according to a fourth embodiment of the invention;

[0079] [Fig. 11] is a cross-sectional view of the output shaft according to the fourth embodiment of the invention of [Fig. 10];

[0080] [Fig. 12] is an isometric view of the output shaft of the transmission shaft coupling system according to a fifth embodiment of the invention;

[0081] [Fig. 13] is a cross-sectional view of the output shaft according to the fifth mode of realization of the invention of [Fig. 12];

[0082] [Fig. 14] is an isometric view of the output shaft of the shaft coupling system of transmission according to a sixth embodiment of the invention;

[0083] [Fig. 15] is a cross-sectional view of the output shaft according to the sixth mode of realization of the invention of [Fig. 14];

[0084] [Fig. 16] is a cross-sectional view of the output shaft according to a seventh mode of realization of the invention;

[0085] [Fig. 17] is a cross-sectional view of the output shaft according to an eighth mode of realization of the invention.

[0086] The features, variants and different embodiments of the invention can be combined with each other in various combinations, provided that they are not incompatible or mutually exclusive.

[0087] Throughout the description, elements common to several figures retain the same reference.

[0088] In the description and claims, the terms "external" and "internal" and the orientations "axial" and "radial" shall be used to designate, according to the definitions given in the description, elements of the transmission system. By convention, the "radial" orientation is directed orthogonally to the first axis of rotation X of the coupling system determining the "axial" orientation, and, from the inside out and away from said axis, the "circumferential" orientation is directed orthogonally to the first axis of rotation X and orthogonally to the radial direction.

[0089] Figures 1 to 5 illustrate a transmission shaft coupling system 1 according to a first embodiment of the invention. We will first describe the operation of a transmission shaft coupling system in general.

[0090] The driveshaft coupling system 1 is here a connecting clutch between two shafts 2, 3 which is used, in a vehicle's drivetrain, to transmit torque from a thermal or electric motor, not shown, to a wheel shaft 7 of a motor vehicle. Such a driveshaft coupling system can, for example, be part of a secondary drivetrain capable of transmitting torque from a secondary motor of the vehicle, such as an electric motor, to a rear or front axle of a vehicle, while a primary drivetrain is capable of transmitting torque from a main motor, for example, a thermal engine, to the wheel shafts of another axle of the vehicle. When the reversible electric machine associated with the gearbox With the speed control inactive, there is no point in leaving the machine connected to the vehicle's wheel. The connection clutch is then disengaged.

[0091] The transmission shaft coupling system 1 is kinematically interposed between a speed reducer and the wheel shaft 7 of the vehicle. The output of the speed reducer is rotationally fixed to a drive shaft 2 of the transmission about a first axis of rotation X. The drive shaft 2 of the transmission includes a first transmission spline 2a machined on its end; in this example, the first transmission spline is external.

[0092] The transmission shaft coupling system 1 also includes a driven transmission shaft 3 coaxial with the driving shaft 2, comprising a second transmission spline 3a, the second transmission spline being external in this example. The driven shaft 3 is inserted into the driving shaft 2 and guided in rotation by means of a guide bearing 4 around the first axis of rotation X. The driven transmission shaft 3 also includes an internal torque output spline 3b rotationally connected with the wheel shaft 7 of the vehicle.

[0093] The transmission shaft coupling system 1 uses a dog clutch sleeve 30 to connect the two driving and driven shafts 2, 3. The dog clutch sleeve 30 is axially movable about the first axis of rotation X and includes a first connecting spline 33 adapted to drive the driving shaft 2 in rotation and a second connecting spline 34 adapted to drive the driven shaft 3 in rotation. In this example, the first and second connecting splines 33, 34 are external and are complementary to the first and second transmission splines 2a, 3a.

[0094] To actuate the transmission shaft coupling system 1, an electrically powered actuating device 10 is used. The actuating device 10 comprises an electric motor 11 kinematically linked to a speed reduction device 13, an output shaft 40 of the speed reduction device rotating about a second axis of rotation Y, and an interface component 20, for example an actuating cam, disposed at the end of the output shaft which interacts with the dog clutch sleeve 30. The interface component 20 is arranged, in particular, to pivot within a receiving housing 31 formed directly in the dog clutch sleeve 30. The receiving housing 31 of the dog clutch sleeve 30 is in the form of a groove composed of two lateral edges 32 and a cylindrical bottom 35 and receives the interface component of the output shaft.

[0095] As illustrated in Figures 4 and 5, the interface component 20 can pivot relative to the output shaft 40 under certain conditions which will be explained later.

[0096] This actuation device 10 also includes a protective housing 18 which protects the electric motor 11 and supports the speed reduction device 13. The protective housing 18 is mounted on a protective sleeve 9 of the transmission system 1. The protective sleeve 9 is cylindrical in shape with its axis coinciding with the first axis of rotation X and has an opening for the output shaft 40 of the actuation device to pass through.

[0097] As illustrated in [Fig. 3], the dog clutch sleeve 30 moves axially between two extreme disengaged and engaged positions when the output shaft 40 pivots about its second axis of rotation Y by a predetermined angular sector. The dog clutch sleeve 30 moves axially by a value Dx relative to the driven transmission shaft 3, which is axially fixed.

[0098] When the dog clutch sleeve 30 is in the first extreme disengagement position, the second connecting spline 34 is disengaged from the second drive spline of the driven shaft 3. The second connecting spline 34 is broken to reduce the engagement stroke.

[0099] When the dog clutch sleeve 30 is in the second extreme coupling position, the first and second connecting splines 33, 34 are engaged respectively in the first drive spline 2a of the driving shaft 2 and the second drive spline 3a of the driven shaft 3.

[0100] The receiving housing 31 of the dog clutch sleeve 30 is in the form of a groove composed of two lateral edges 32 and a cylindrical bottom 35 and receives the interface component 20 of the actuating device. In this case, the interface component is in the form of the actuating cam 20. The two lateral edges 32 are formed from the same material as the dog clutch sleeve.

[0101] We will now describe the general operation of the transmission shaft coupling system when we are in a favorable case of engagement of the teeth of the dog clutch sleeve 30 with the second drive spline of the driven shaft 3.

[0102] The actuating cam 20 has two contact areas 20a, 20b bearing on the parallel surfaces 32a of the receiving housing. The bearing width L along the first axis of rotation X separating the two contact areas is constant throughout the rotation of the output shaft. To ensure free movement of the actuating cam 20 within the annular groove without unwanted friction, an operating clearance is defined between the bearing width L of the actuating cam and the axial distance D separating the two parallel surfaces 32a of the receiving housing 31 along the first axis of rotation X.

[0103] As illustrated in [Fig. 2], the actuating cam 20 comprises three actuating faces 21 formed in the form of a portion of a cylinder, the three centers A portion of the cylinder 22 forms an isosceles triangle, the principal vertex of the isosceles triangle coinciding with the second axis of rotation Y of the output shaft 40. The geometry of the contact areas 20a, 20b of the actuating cam uses large-diameter cylinder portions to reduce the contact pressure with the parallel surfaces of the receiving housing. During rotation of the actuating cam, the actuating face 21 slides on one of the parallel surfaces 32a. In this first embodiment, the actuating cam 20 has a symmetrical actuation profile whose axis of symmetry passes through the bisector 37 of the isosceles triangle, the bisector of the isosceles triangle corresponding to the midpoint of the second angular sector a2. The isosceles triangle has a height H and a principal angle [3, for example, between 45° and 150°. The actuating cam 20 thus has a symmetrical profile passing through the second axis of rotation Y.

[0104] Thanks to the specific geometry of the actuating cam profile, the operating clearance between the bearing width L of the actuating cam and the distance D is constant throughout the rotation of the output shaft. The operating clearance is on the order of 0.1 mm to 0.6 mm. The actuation accuracy is thus improved.

[0105] To ensure free movement of the actuating cam 20 within the receiving housing 31 without unwanted friction, the actuating faces 21 of the actuating cam 20 are connected by a cylindrical connecting face 23 with a radius R2 smaller than the radius RI of the cylindrical segments, the connecting radius being between 1 and 5 mm. During rotation of the actuating cam, the cylindrical connecting face 23 also slides on one of the parallel surfaces 32a. The contact areas 20a, 20b of the actuating cam are alternately formed by an actuating face 21 and / or a cylindrical connecting face 23. The geometry of the contact area 20a, 20b then has a radius RI or a radius R2.

[0106] In order to recenter the actuating cam 20 in the receiving housing 31, the first axis of rotation X of the dog clutch sleeve 30 is not intersecting the second axis of rotation Y. For example, the second axis of rotation Y is offset with respect to a plane parallel to the second axis of rotation Y and passing through the first axis of rotation X by a value of a few millimeters.

[0107] We will now describe the operation of the actuation device allowing the transition from the first extreme uncoupling position to the second extreme coupling position with a reduced actuation time.

[0108] As illustrated in [Fig.3], the output shaft 40 is arranged to pivot around three adjacent angular sectors al, a2, a3, a first angular sector al, a second angular sector a2 which is adjacent to the first angular sector al, a third angular sector a3 which is adjacent to the second angular sector a2. The sum of the three angular sectors al, a2, a3 corresponds to the predetermined angular sector a.

[0109] Initially, the dog clutch sleeve 30 is in its first extreme disengaged position. The dog clutch sleeve 30 remains axially stationary in this first extreme position when the output shaft rotation is within the first angular sector. The angle of this first angular sector al1 is 15°. Within this first angular sector al1, the dog clutch sleeve 30 remains in a stable position that allows the electrical supply to the actuation device to be cut off, thus reducing the vehicle's electrical consumption.

[0110] In a second step, the dog clutch sleeve 30 moves axially between the two extreme disengagement and engagement positions when the output shaft 40 pivots through the entire second angular sector a2. The displacement Dx of the dog clutch sleeve 30 is shown in [Fig. 3]. The angle value of the second angular sector a2 is approximately 100°.

[0111] In a third step, the dog clutch sleeve 30 remains axially fixed in the second extreme position when the rotation of the output shaft is within the third angular sector a3. The angle value of the third angular sector a3 is approximately 5°. Within this third angular sector a3, the dog clutch sleeve 30 remains in a stable position which allows the electrical supply to the actuation device to be cut off, thus reducing the vehicle's electrical consumption.

[0112] Thanks to the specific geometry of the actuating cam profile, the bearing width L along the first axis of rotation X separating the two contact zones 20a, 20b is constant over the three angular sectors a1, a2, a3 of rotation of the output shaft. Figure 3 also illustrates the different angular positions taken by the actuating cam 20 during the displacement Dx of the dog clutch sleeve 30.

[0113] To improve the reliability of the transmission shaft coupling system 1, an elastic damping means 50 acting in torsion along the second axis of rotation Y is disposed between the output shaft 40 and the actuating cam 20 of the actuating device.

[0114] In this first embodiment of the invention, the elastic damping means 50 is a torsion spring which allows an angular displacement of the interface component 20 relative to the output shaft 40 according to an angle value 0 equal to 15°.

[0115] As illustrated in Figures 4 and 5, the torsion spring 50 is a blade 53 wound around the second axis of rotation Y, made from a flat wire. The flat wire is made of steel. The angular stiffness of the elastic damping means is 0.5 Nm / °. The torsion spring 50 comprises a first end 51 inserted into the output shaft 40 and a second end 52 inserted into the actuating cam 20.

[0116] The output shaft 40 mainly has a shape of revolution, in particular a cylindrical bearing surface 44 which pivots in the protective housing 18 of the Actuation device 10. The output shaft 40 supports the elastic damping means 50 and includes a first projection 41 disposed on the end of the shaft. The first projection 41 receives the actuating cam 20 and the torsion spring 50. In particular, a support slot 43 is provided in the first projection 41 to retain the first end 51 of the torsion spring.

[0117] The actuating cam 20 includes a hollow housing 26 comprising two stop faces 27 that limit the angular deflection relative to the first protrusion 41 of the output shaft. The torsion spring 50 applies a preload torque between the output shaft and the interface component, the value of the preload torque being between 0.5 Nm and 5 Nm. Thus, one of the stop faces 27 of the actuating cam 20 is pressed against the output shaft 40 when the actuating device is inactive.

[0118] The output shaft 40 also includes a second cylindrical projection 42 with an axis concentric to the second axis of rotation Y and disposed on the end of the first projection 4L. The actuating cam 20 pivots around the second projection 42 by means of a bore which opens into the hollow housing 26.

[0119] Preferably, the elastic damping means 50 comprises an axial retaining washer 55 fixed to the second projection 42, for example inserted into a mounting groove. The axial retaining washer 55 maintains the actuating cam 20 in axial position on the output shaft 40, particularly during assembly phases.

[0120] The output shaft 40 also includes a toothed ring 45, here an internal toothed ring that meshes with another gear of the speed reduction device 13. The speed reduction device 13 comprises, in this first embodiment of the invention, a spur gear train. The toothed ring 45 of the output shaft participates in the final speed reduction stage of the electric motor 11.

[0121] When the transmission shaft coupling system 1 is in the first extreme disengagement position, the electric transmission is stopped. The rotor of the electric machine does not rotate, so the speed of the driving shaft 2 is different from the rotational speed of the driven shaft 3, which corresponds to that of the vehicle's wheels.

[0122] In this first extreme disengagement position, the torsion spring 50 applies a preload torque between the output shaft 40 and the actuating cam 20 of a value of 2 Nm.

[0123] When engaging the teeth of the internal spline of the dog clutch sleeve 30 within the second transmission spline 3a of the driven shaft 3, the rotational speed of the driving shaft 2 is first adjusted to be as close as possible to the rotational speed of the driven shaft 3, while maintaining a slight speed differential between the two shafts 2 and 3. When the speed setpoint When the leading shaft 2 is reached, the teeth of the internal groove of the dog clutch sleeve 30 are inserted. The dog clutch sleeve 30 is moved axially by rotating the output shaft 40 of the actuation device 10 around the second axis of rotation Y.

[0124] In the favorable case where the teeth of the internal spline of the dog clutch sleeve 30 are aligned with the grooves of the second transmission spline 3a of the driven shaft 3, the dog clutch sleeve 30 slides axially along the driven shaft 3 and transmits only a small parasitic axial force to the actuating cam 20 generated by the friction of the splines against each other. The torsion spring 50 is not stressed or only slightly stressed in this favorable case.

[0125] In a first unfavorable case where the teeth of the internal spline of the dog clutch sleeve 30 are aligned with the crests of the second transmission spline 3a of the driven shaft 3, the dog clutch sleeve 30 cannot slide axially. The pivoting of the output shaft 40 causes the actuating cam 20 to rotate about the second axis of rotation Y, while the dog clutch sleeve 30 remains axially fixed. The torsion spring 50 deforms to compensate for the pivoting of the output shaft 40 up to a certain deformation value. The deformation of the torsion spring 50 dampens the pivoting of the output shaft 40 and prevents a shock from being transmitted back into the speed reduction device 13 of the actuating device 10.

[0126] In a second unfavorable case, where the teeth of the internal spline of the dog clutch sleeve 30 are almost aligned with the grooves of the second transmission spline 3a of the driven shaft 3, the dog clutch sleeve 30 begins to slide axially and the teeth of the spline of the dog clutch sleeve begin to penetrate the spline of the driven shaft. It may happen, when the difference in rotational speed between the driven shaft 3 and the driving shaft 2 is too great, that the insertion attempt fails simply because the time available for the internal and external splines to be fully aligned is too short. The teeth of the spline of the dog clutch sleeve are then abruptly ejected from the spline of the driven shaft 3 while the rotation of the output shaft 40 continues.

[0127] The torsion spring 50 deforms to compensate for the pivoting of the output shaft.

[0128] The pivoting of the output shaft 40 causes the interface component 20 to rotate around the second axis of rotation Y, while the dog clutch sleeve 30 moves backward toward the driving shaft. This combined movement causes the torsion spring 50 to deform, damping the pivoting of the output shaft 40 up to a certain deformation value and preventing a shock from being transmitted back into the speed reduction device 13 of the actuation device 10. This prevents the shock rebound in the output shaft 40 and avoids creating damage in the speed reduction device 13 of the actuation device which includes teeth not sized to receive such a temporary overtorque.

[0129] The deformation can reach up to the maximum winding value of the torsion spring. In this first embodiment of the invention, the shocks associated with a failure of tooth engagement are absorbed outside the speed reduction device of the actuation device.

[0130] We will now describe, with reference to Figures 6 and 7, a second embodiment of the invention, which differs from the first embodiment by an inverted structure of the elastic damping means 50. The interface component 20 is here an actuating cam comprising an extension 28a while the output shaft 40 comprises a hollow housing 46a arranged to accommodate said extension.

[0131] In this second embodiment, the elastic damping means 50, acting in torsion about the second axis of rotation Y, is disposed between the output shaft 40 and the actuating cam 20 of the actuating device. The elastic damping means 50 is a torsion spring that allows an angular displacement of the interface component 20 relative to the output shaft 40 by an angle θ equal to 15°.

[0132] As illustrated in Figures 6 and 7, the torsion spring 50 is a blade 53a wound around the second axis of rotation Y, made from a flat wire. The flat wire is made of steel. The torsion spring 50 comprises a first end 51a inserted into the projection 28a of the actuating cam 20 and a second end 52a inserted into the hollow housing 46a of the output shaft 40. In particular, a support slot 29a is provided in the projection 28a of the actuating cam 20 to retain the first end 51 of the torsion spring.

[0133] The hollow housing 46a of the output shaft 40 includes two stop faces 47a that limit the angular deflection relative to the protrusion 28a of the actuating cam 20. The torsion spring 50 applies a preload torque between the output shaft and the interface component, the value of the preload torque being between 0.5 Nm and 5 Nm. Thus, one of the stop faces 47a of the output shaft 40 is pressed against the actuating cam 20 when the actuating device is inactive.

[0134] Also, the elastic damping means 50 includes a rivet 56 fixed on the output shaft 40. The rivet 56 maintains the actuating cam 20a in axial position on the output shaft 40, particularly during assembly phases, while allowing the actuating cam 20 to pivot around the axis of the rivet.

[0135] The output shaft 40 also includes a toothed ring 45, here an internal toothed ring which meshes with another gear of the speed reduction device 13.

[0136] We will now describe, with reference to figures 8 and 9, a third embodiment of the invention, which differs from the first embodiment in that the elastic damping means 50 is made in the form of a helical torsion spring with round wire.

[0137] In this third embodiment of the invention, the elastic damping means 50 acting in torsion about the second axis of rotation Y is disposed between the output shaft 40 and the actuating cam 20 of the actuation device. The elastic damping means 50 is a torsion spring that allows an angular displacement of the interface component 20, in the form of an actuating cam, relative to the output shaft 40 by an angle θ equal to 15°.

[0138] As illustrated in Figures 8 and 9, the torsion spring 50 is a steel wire wound around the second rotation Y. The helical, round-wire torsion spring 50 comprises a first end 51b inserted into a cylindrical bore of the output shaft 40 and a second end 52b inserted into a support slot 29b of the actuating cam 20. The first and second ends 51b, 52b are oriented in the same direction and toward the actuating cam 20. The second end 52b has a 90° bend. The actuating cam 20 is axially retained on the output shaft 40 by the bent second end 52b of the torsion spring 50. The bent second end 52b forms an axial retaining hook for the actuating cam.

[0139] The output shaft 40 is primarily of a revolution shape, including a cylindrical bearing surface 44 that pivots within the protective housing 18 of the actuating device 10. The output shaft 40 supports the elastic damping means 50 via a hollow housing 46b and includes a first projection 41b located on the end of the shaft. The torsion spring 50 is guided by the bore of the hollow housing 46b. The first projection 41b receives the actuating cam 20. In particular, a passage slot 43b is provided in the first projection 41b to allow the second end 52b of the torsion spring to pass through during assembly of the actuating device.

[0140] The output shaft 40 also includes a toothed ring 45, here an internal toothed ring which meshes with another gear of the speed reduction device 13. The speed reduction device 13 includes in this third embodiment of the invention a cycloidal reducer.

[0141] We will now describe, with reference to Figures 10 and 11, a fourth embodiment of the invention, which differs from the first embodiment in that the elastic damping means 50 is made in the form of a helical torsion spring with round wire.

[0142] In this fourth embodiment of the invention, the elastic damping means 50 acting in torsion about the second axis of rotation Y is disposed between the output shaft 40 and the actuating cam 20 of the actuation device. The elastic damping means 50 is a torsion spring that allows an angular displacement of the interface component 20, in the form of an actuating cam, relative to the output shaft 40 by an angle θ equal to 15°.

[0143] As illustrated in Figures 10 and 11, the torsion spring 50 is a steel wire wound around the second rotation Y. The output shaft 40 supports the elastic damping means 50 via a hollow housing 46c. The helical torsion spring 50 with round wire comprises a first end 51c inserted into a cylindrical bore of the output shaft 40 and a second end 52c inserted into a cylindrical bore of the actuating cam 20. The first and second ends 51c, 52c are oriented in different directions.

[0144] The output shaft 40 supports the elastic damping means 50 and includes a first projection 41c disposed on the end of the shaft. The first projection 41c receives the actuating cam 20.

[0145] The actuating cam 20 includes a hollow housing 26c comprising two stop faces which limit the angular deflection relative to the first protrusion 41c of the output shaft.

[0146] The output shaft 40 also includes a second cylindrical projection 42c with an axis concentric to the second axis of rotation Y and disposed on the end of the first projection 41c. The actuating cam 20 pivots around the second projection 42c by means of a bore which opens into the hollow housing 26c.

[0147] Preferably, the elastic damping means 50 comprises an axial retaining washer 55 fixed to the second projection 42, for example inserted into a mounting groove. The axial retaining washer 55 maintains the actuating cam 20 in an axial position on the output shaft 40, particularly during assembly phases.

[0148] We will now describe, with reference to Figures 12 and 13, a fifth embodiment of the invention, which differs from the fourth embodiment in that the actuating cam 20 is stopped in rotation by stop faces 47d made directly in the cylindrical bearing surface 44 of the output shaft 40.

[0149] In this fourth embodiment of the invention, the elastic damping means 50 acting in torsion along the second axis of rotation Y is arranged between The output shaft 40 and the actuating cam 20 of the actuating device. The elastic damping means 50 is a helical torsion spring with round wire which allows an angular displacement of the actuating cam 20 relative to the output shaft 40 by an angle value 0 equal to 15°.

[0150] As illustrated in Figures 12 and 13, the torsion spring 50 is a steel wire wound around the second rotation Y. The helical, round-wire torsion spring 50 comprises a first end 51d inserted into a through slot in the output shaft 40 and a second end 52d inserted into a support slot 29d in the actuating cam 20. The first and second ends 51d, 52d are oriented in different directions. The second end 52d has a 90° bend. The actuating cam 20 is axially retained on the output shaft 40 by the bent second end 52d of the torsion spring 50.

[0151] The output shaft 40 supports the elastic damping means 50 and includes a first projection 41d disposed on the end of the shaft. The first projection 41d serves as a guide for the torsion spring 50. The output shaft 40 also includes a second cylindrical projection 42d with an axis concentric to the second axis of rotation Y and disposed on the end of the first projection 41d. The actuating cam 20 pivots about the second projection 42d.

[0152] The output shaft 40 mainly has a shape of revolution, including in particular a cylindrical bearing 44 which pivots in the protective housing 18 of the actuation device 10. The cylindrical bearing 44 directly integrates the stop faces 47d of the actuation cam 20.

[0153] In this fifth embodiment, the rotation of the interface component is prevented by the bearing of the actuating faces 21 of the actuating cam 20 against the two stopping faces 47d. In particular, the torsion spring 50 applies a preload torque between the output shaft and the interface component, the value of the preload torque being between 0.5 Nm and 5 Nm. Thus, one of the actuating faces 21 of the actuating cam 20 is pressed against one of the stopping faces 47d of the output shaft 40 when the actuating device is inactive.

[0154] The output shaft 40 also includes an external toothed ring 45 which meshes with another gear of the speed reduction device 13.

[0155] We will now describe, with reference to Figures 14 and 15, a sixth embodiment of the invention, which differs from the first embodiment in that the elastic damping means 50 is formed directly by the interface component 20. In this example, the interface component 20 deforms relative to the output shaft 40 of the actuation device along the second axis of rotation Y.

[0156] In this sixth embodiment, the elastic damping means 50 acting in torsion about the second axis of rotation Y is always disposed between the shaft output 40 and interface component 20, the interface component directly fulfilling the additional damping function. The interface component is a blade 53e wound around the second axis of rotation Y, made from a flat wire. The flat wire is made of steel. The wound blade 53e comprises at least three actuation faces 21 formed in the form of a portion of a cylinder, and the three centers of the portion of the cylinder form an isosceles triangle. One of the actuation faces 21 bears against one of the parallel surfaces 32a of the receiving housing of the clutch sleeve 30.

[0157] The wound blade 53e comprises a first end 51e formed from one of the cylinder portions and a second end 52e also formed from one of the cylinder portions. The first and second ends 51e, 52e are oriented in the same direction and towards the output shaft 40.

[0158] To hold the interface component 20 in position, a hollow recess 46e is provided at the end of the output shaft 40. The hollow recess 46e of the output shaft 40 has a square shape. The first and second ends 51e, 52e are inserted into the hollow recess 46e of the output shaft 40.

[0159] In particular, the hollow housing 46e of the output shaft 40 includes two retaining faces 47e that limit the deformation of the wound blade 53e. The torsion spring 50 applies a preload torque between the output shaft and the interface component, the value of the preload torque being between 0.5 Nm and 5 Nm. The first and second ends 51e, 52e are thus pressed against the retaining faces 47e of the output shaft 40 when the actuation device is inactive.

[0160] The output shaft 40 also includes a boss 49e inserted into the internal space left free by the coiled blade 53e. When the attempt to insert the teeth of the spline of the dog clutch sleeve into the spline of the driving shaft is aborted, the coiled blade 53e has the ability to deform until it comes into contact with the boss 49e.

[0161] We will now describe, with reference to [Fig. 16], a seventh embodiment of the invention, which differs from the first embodiment in that the elastic damping means 50 is formed directly by the interface component 20. In this example, the interface component 20 deforms relative to the output shaft 40 of the actuation device along the second axis of rotation Y.

[0162] In this seventh embodiment, the elastic damping means 50, acting in torsion about the second axis of rotation Y, is always located between the output shaft 40 and the interface component 20, the interface component directly fulfilling the additional damping function. The interface component 20 is a blade 53f wound around the second axis of rotation Y, made from a flat wire. The flat wire is made of steel. The wound blade 53f comprises at least Three actuation faces 21 are formed in the form of a portion of a cylinder, and the three centers of the portion of the cylinder form an isosceles triangle. One of the actuation faces 21 bears against one of the parallel surfaces 32a of the receiving housing of the dog clutch sleeve 30.

[0163] The coiled blade 53f comprises a first spiral-shaped end 5 If, formed from one of the cylinder portions 21, and a second free end 52f.

[0164] The output shaft 40 mainly has a general shape of revolution, including in particular a cylindrical bearing surface 44 which pivots in the protective housing 18 of the actuating device 10. The output shaft 40 supports the wound blade 53f and includes a first projection 41f disposed on the end of the shaft. The first projection 41f receives the wound blade 53f. In particular, a support slot 43f is provided in the first projection 41f to retain the first end 51f of the wound blade 53f.

[0165] The output shaft 40 also includes a boss 49f inserted into the internal space left free by the coiled blade 53f. When the attempt to insert the teeth of the spline of the dog clutch sleeve into the spline of the driving shaft is aborted, the coiled blade 53f has the ability to deform until it comes into contact with the boss 49f.

[0166] We will now describe, with reference to [Fig. 17], an eighth embodiment of the invention, which differs from the first embodiment in that the interface component 20 is an eccentric actuation rod with respect to the second axis of rotation Y of the actuation device.

[0167] Generally, the eccentric actuating rod 20 is a cylindrical component that is inserted into the receiving housing 31 of the dog clutch sleeve 30.

[0168] The elastic damping means 50 is a helical torsion spring with round wire which allows an angular displacement of the interface component 20, made in the form of an actuating cam, relative to the output shaft 40 according to an angle value 0 equal to 15°.

[0169] As illustrated in [Fig. 17], the torsion spring 50 is a steel wire wound around the second rotation Y. The helical, round-wire torsion spring 50 comprises a first end 51g inserted into a cylindrical bore of the output shaft 40 and a second end 52g inserted into a cylindrical bore of the eccentric actuating rod 20. The first and second ends 51g, 52g are oriented in different directions. The eccentric actuating rod 20 is held in position by the second end 52g of the torsion spring 50.

[0170] The eccentric actuating rod 20 is a roller bearing. The axis of rotation of the roller bearing is parallel and distant from the second axis of rotation Y.

[0171] The output shaft 40 mainly has a general shape of revolution, including in particular a cylindrical bearing surface 44 which pivots in the protective housing 18 of the actuation device 10. A closing cover 48g fitted onto a part of the cylindrical bearing surface 44 maintains the torsion spring 50 in an axial position. An oblong shape provided on the closing cover 48g ensures the guidance of the eccentric actuating rod 20 and allows an angular displacement of the eccentric actuating rod 20 relative to the output shaft 40 by an angle value 0 equal to 15°.

[0172] The present invention is not limited to the means and configurations described and illustrated herein and extends also to any equivalent means and configuration as well as to any technically operative combination of such means.

Claims

Demands

1. Transmission shaft coupling system (1), comprising: - a transmission drive shaft (2) including a first drive spline (2a); - a transmission driven shaft (3) coaxial to the driving shaft including a second drive spline (3a); - a dog clutch sleeve (30) including at least a first connecting spline (33) adapted to drive the driving shaft (2) in rotation about a first axis of rotation (X) and a second connecting spline (34) adapted to drive the driven shaft (3);- an actuation device (10) comprising an electric motor (11) kinematically linked to a speed reduction device (13), an output shaft (40) of the speed reduction device rotating about a second axis of rotation (Y), an interface component (20) disposed at the end of the output shaft (40) and arranged to pivot within a receiving housing (31) formed in the dog clutch sleeve, the dog clutch sleeve (30) being able to move axially along the first axis of rotation (X) between a first extreme disengagement position and a second extreme engagement position when the output shaft pivots along a predetermined angular sector (a), characterized in that an elastic damping means (50) acting in torsion along the second axis of rotation (Y) is disposed between the output shaft (40) and the interface component (20) of the actuation device.;

2. A drive shaft coupling system (1) according to claim 1, wherein the predetermined angular sector is between 20° and 180°, allowing the dog clutch sleeve to move from the first extreme disengagement position, in which one of the first or second connecting splines (33, 34) is disengaged from either the first drive spline (2a) of the driving shaft or the second drive spline (3a) of the driven shaft, to the second extreme coupling position, in which the first and second connecting splines (33, 34) are engaged respectively in the first drive spline (2a) of the driving shaft and the second drive spline (3a) of the driven shaft.

3. Transmission shaft coupling system (1) according to claim 1 or 2, wherein the elastic damping means (50) comprises a torsion spring which permits angular displacement of the interface component (20) relative to the output shaft (40) by an angle value (0) between 5° and 20°.

4. Transmission shaft coupling system (1) according to the preceding claim, wherein the torsion spring (50) applies a preload torque between the output shaft (40) and the interface component (20), the value of the preload torque being between 0.5 Nm and 5 Nm, the interface component being pressed directly or indirectly onto the output shaft when the actuation device (10) is inactive.

5. Transmission shaft coupling system (1) according to any one of the preceding claims, wherein the output shaft (40) comprises at least one first projection (41, 41b, 41c, 41d, 41f) disposed on the end of the shaft, the interface component (20) comprises a hollow housing (26) which surrounds the first projection, the hollow housing (26) comprising two stop faces (27) which limit the angular deflection relative to the first projection of the output shaft.

6. Transmission shaft coupling system (1) according to the preceding claim, wherein the output shaft (40) comprises a second cylindrical projection (42, 42c, 42d) with an axis concentric to the second axis of rotation (Y) and disposed on the end of the first projection, the interface component (20) pivoting around the second projection by means of a bore which opens into the hollow housing.

7. Transmission shaft coupling system (1) according to any one of claims 3 to 6, wherein the torsion spring (50) is for example a blade wound (53, 53a) around the second axis of rotation (Y) made from a flat wire.

8. A transmission shaft coupling system (1) according to the preceding claim, wherein the torsion spring (50) comprises a first end (51) inserted into a support slot formed in the output shaft (40) and a second end (52) inserted into a hollow housing (26) of the interface component (20).

9. Transmission shaft coupling system (1) according to any one of claims 3 to 6, wherein the torsion spring (50) is a helical round wire torsion spring comprising a first end (51b, 51c, 51d, 51g) inserted into a cylindrical bore of the output shaft and a second end (52b, 52c, 52d, 52g) inserted into a cylindrical bore or slot of the interface component (20).

10. Transmission shaft coupling system (1) according to claim 3 or 4, wherein the elastic damping means (50) is formed directly by the interface component, the interface component being for example a blade wound around the second axis of rotation (Y) made from a flat wire, the wound blade (53e, 53f) comprising at least three actuation faces (21) made in the form of a portion of a cylinder and the three centers of the portion of a cylinder form an isosceles triangle.

11. Transmission shaft coupling system (1) according to any one of claims 1 to 9, wherein the interface component is an actuating cam (20) pivoting about the second axis of rotation (Y) of the actuating device, the actuating cam comprising three actuating faces (21) made in the form of a portion of a cylinder and the three centers of the portion of a cylinder form an isosceles triangle.

12. Transmission shaft coupling system (10) according to the preceding claim, wherein the actuating cam (20) has two contact areas (20a, 20b) arranged to bear on parallel surfaces (32a) of the receiving housing (31), the bearing width (L) along the first axis of rotation (X) separating the two contact areas is constant over the predetermined angular sector (a) of rotation of the output shaft.

13. Transmission shaft coupling system (1) according to claim 9, wherein the interface component (20) is an eccentric actuating rod with respect to the second axis of rotation (Y) of the actuating device, the eccentric actuating rod being a cylindrical component which is inserted into the receiving housing (31) of the dog clutch sleeve (30).

14. Transmission shaft coupling system (1) according to any one of the preceding claims, wherein the receiving housing (31) of the dog clutch sleeve (30) is in the form of a groove composed of two lateral rims (32) and a cylindrical bottom (35) and receives the interface component (20) of the output shaft (40).

15. A drive shaft coupling system (1) according to any one of the preceding claims, wherein the dog clutch sleeve (30) comprises at least one first internal connecting spline (33) arranged to drive the driving shaft (2) in rotation and a second internal connecting spline (34) arranged to drive the driven shaft (3) in rotation, the first and second internal splines (33, 34) being engaged respectively in a first external transmission spline (2a) of the driving shaft and a second external transmission spline (3a) of the driven shaft when the dog clutch sleeve (30) is in the second extreme coupling position.