Coupling sub-assembly for motor vehicle differential

Abstract

The invention relates to a coupling sub-assembly (10) for a motor vehicle differential comprising: - a coupling ring (11) having a cylindrical body (11a) with a main axis of rotation (X) and a coupling toothing formed on the cylindrical body suitable for coupling onto an axial coupling slider (21), - at least two satellite gears (14, 14a, 15, 15a) which are mounted for rotation on the coupling ring (11) around a second axis (Z, Z') perpendicular to the main axis of rotation (X);- and two planetary gears (16, 17) which are free to rotate about the main axis of rotation (X), each planetary gear meshing with the satellite gears (14, 14a, 15, 15a) and intended to be rotationally fixed to a wheel shaft (2, 3) of the motor vehicle, in which the satellite gears pivot about a rod (12) which passes through the cylindrical body of the coupling ring along the second axis (Z, Z'). Figure for the abbreviation: Fig. 2;

Description

Title of the invention: Coupling sub-assembly for motor vehicle differential technical field

[0001] The invention relates to the field of motor vehicle differentials, and in particular to differentials equipped with a coupling sub-assembly.

[0002] It relates more particularly to a differential-type transmission system designed to transmit and distribute torque from an electric or internal combustion engine to two wheel shafts of a vehicle axle. The differential comprises a first element, for example a main assembly intended to be driven by a motor, a second element, for example a coupling sub-assembly intended to drive at least one wheel shaft of a vehicle, and a coupling device capable of selectively coupling or uncoupling the first element to the second element. Technological background

[0003] Document DE102013111891 Al discloses a differential transmission system. The transmission system comprises a differential housing that rotates about an axis A and is equipped with a gear driven by a vehicle engine. Inside the housing are housed a rotating ring gear, two satellite gears that are mounted for rotation on the ring gear about an axis B perpendicular to axis A, and two planetary gears, each of which meshes with the two satellite gears and is each rotationally fixed to a wheel shaft. Used in a motor vehicle's drivetrain, the differential transmission system allows the drive wheels to rotate at different speeds when cornering: the wheels on the outside of the turn rotate faster than those on the inside.

[0004] Furthermore, the transmission system includes a coupling device that allows either the transmission system housing to be coupled to the coupling ring to enable the transmission and distribution of torque from the engine to the two wheel shafts of the axle, or it allows them to be uncoupled to interrupt the transmission of torque between the engine and the wheel shafts. The coupling device is controlled by an electromagnetic actuator. The coupling device is a dog clutch device. It comprises a first coupling portion having an annular portion located outside the housing and projecting elements extending from the annular portion and passing through it. Openings are provided in the housing, allowing the first coupling part and the housing to be rotationally locked together. The second coupling part of the coupling device comprises the coupling ring. The protruding elements of the first coupling part have teeth designed to engage with complementary grooves on the coupling ring. The first coupling part is axially movable relative to the housing between an uncoupled position and a coupled position in which the teeth of the first coupling part mesh with the grooves of the coupling ring.

[0005] In this coupling device, the torque from the electric motor is transmitted via teeth formed at the end of the coupling ring and protruding elements. This toothed transmission is therefore distributed over only a few angular sectors, which limits the number of teeth meshing with the complementary teeth on the coupling ring. The torque transmission capacity of such a transmission system is limited.

[0006] Such a transmission system is also not entirely satisfactory in terms of internal deformation of the components, particularly the coupling ring when it transmits torque to the wheel shafts. The coupling ring is a large-diameter component through which a rod passes, supporting the planet gears. This coupling ring deforms under the effect of the actuation forces of the planet gears, which tend to deform the cylindrical body of the coupling ring in the direction of the rod. These deformations are detrimental to the precision of the teeth of the dog clutch. Furthermore, the durability of the differential gears will be affected by wear on the meshing teeth due to the deformations undergone by the coupling ring. Summary

[0007] One idea underlying the invention is to propose a transmission system with a high torque transmission capacity whose assembly would be simplified and whose component called "coupling ring" would be simpler to manufacture.

[0008] The invention aims to remedy this problem by proposing a coupling subassembly for a motor vehicle differential comprising:

[0009] - a coupling ring having a cylindrical body with an axis of main rotation X and a coupling toothing formed on the cylindrical body suitable for coupling onto an axial coupling slider,

[0010] - at least two satellite gears which are mounted for rotation on the crown coupling around a second axis Z, Z' perpendicular to the main axis of rotation X;

[0011] - and two planetary gears which are movable in rotation about the axis of Main rotation X, each planetary gear meshes with the sa- gears tellites and intended to be rotationally fixed to a wheel shaft of the motor vehicle,

[0012] the coupling sub-assembly being notable in that the satellite gears pivot around at least one rod which passes through the cylindrical body of the coupling ring along the second axis Z, Z' and at least one rod is held in position relative to the coupling ring by a locking means which acts in the direction of the second axis Z, Z', at least one rod being supported on an external surface of the cylindrical body.

[0013] In this coupling sub-assembly, the support of the rod(s) on the external surface of the cylindrical body increases the rigidity of the coupling ring and has the advantage of transmitting high torques within a differential placed between the electric or thermal motor and the wheels of the motorized vehicle.

[0014] At least one rod participates in transferring the actuation forces of the satellite gears to the cylindrical body and provides an internal loop of the forces within the coupling sub-assembly. This limits the radial expansion of the coupling ring under the effect of the actuation forces of the satellite gears, which tend to deform the cylindrical body in the direction of the second axis Z, Z'.

[0015] The external surface of the cylindrical body is essentially cylindrical but may locally include bearing surfaces for at least one rod, formed in the form of a flat, a concave surface, or any other shape suitable for receiving the support of a rod. The flat surface of the flat improves the accuracy of the tightening torque applied to the rod.

[0016] According to one embodiment of the invention, the locking means for at least one rod can be a screw assembly that is oriented coaxially with respect to the second axis Z, Z'. In this way, the assembly of the coupling sub-assembly is simplified because it is not necessary to invest in heavy and sophisticated tooling.

[0017] Preferably, each planetary gear can pivot about a separate rod. Each rod has a shoulder that bears against the external surface of the cylindrical body. Each rod is tensioned by tightening the bolted assembly and applies a mechanical preload to the cylindrical body along the second axis Z, Z' via the shoulder. In this way, each rod contributes to absorbing the actuation forces of the planetary gears and provides an internal loop of forces within the coupling subassembly.

[0018] Advantageously, the shoulder of each rod can be inscribed within the cylindrical external volume of the coupling ring. The coupling subassembly has the advantage of being radially compact. The mass of the coupling subassembly is also reduced.

[0019] Preferably, the shoulder of each rod can bear against a flat formed on the external surface of the cylindrical body. The coupling subassembly has the advantage of being radially compact.

[0020] Advantageously, the screw assembly can be made directly by screwing rods together or by screwing a single rod and end screws, or the screw assembly can be made indirectly by screwing rods into an assembly nut.

[0021] Preferably, in the case of an indirectly screwed assembly, at least two rods can be screwed into the assembly nut, the assembly nut comprising drilled and tapped holes associated with each of the rods and each of the drilled and tapped axes is perpendicular to the main axis of rotation X. For example, four rods are assembled in the assembly nut.

[0022] Advantageously, the rod may include a cylindrical portion, a threaded end and a shoulder.

[0023] Preferably, the threaded ends of the rods can be inserted into the drilled and tapped holes of the assembly nut.

[0024] According to one example, the stems can be identical.

[0025] Advantageously, the assembly nut may include a central bore, coaxial with the main axis of rotation X and suitable for receiving the end of a wheel shaft.

[0026] Preferably, the assembly nut may include an axial bearing surface for each rod, each bearing surface is annular and concentric with the second axis Z, Z'.

[0027] Alternatively, the assembly nut may include an axial bearing surface for each rod, each bearing surface is of arbitrary shape and oriented axially along the second axis Z, Z'.

[0028] Preferably, in the case of a screwed assembly made directly by screwing a single rod and end screws, the rod has a shoulder at one end which bears against the external surface of the cylindrical body of the coupling ring, a cylindrical portion and a drilled and tapped hole made at the end of the rod into which the end screw is inserted.

[0029] Preferably, in the case of a screwed assembly made directly by screwing rods together, a first rod has a cylindrical portion and a threaded end, a second rod has a cylindrical portion and a drilled and tapped hole made at the end of the rod into which the threaded end of the first rod is inserted.

[0030] According to another embodiment of the invention, the locking means for at least one rod can be a riveted assembly oriented coaxially with respect to the second Z-axis. In this way, the assembly of the coupling sub-assembly is economical because it is not necessary to add any additional components. to make it.

[0031] Preferably, the planetary gears can pivot about a single rod. The rod has a shoulder at one end and a flange at the other end, which bear against the external surface of the cylindrical body. The rod is tensioned by riveting and applies a mechanical preload to the cylindrical body along the second Z-axis via the shoulder and flange. In this way, the rod helps to transfer the actuation forces of the planetary gears to the cylindrical body and provides an internal loop of forces within the coupling subassembly.

[0032] Advantageously, the shoulder and the end cap of the rod can be inscribed within the cylindrical external volume of the coupling ring. The coupling subassembly has the advantage of being radially compact.

[0033] Alternatively, riveting oriented coaxially with respect to the second Z axis can be carried out between a rod and an assembly nut.

[0034] According to another embodiment of the invention, the means for locking at least one rod can be a welded assembly, for example, electron beam welding, securing the rod and the coupling ring or securing the rod and the assembly nut. A clamping force on the rod against the coupling ring is applied during the welding operation. This force is oriented along the second axis Z, Z'. This results in better alignment of the gears under load, which contributes to the transfer of the actuation forces of the planetary gears within the coupling subassembly. The durability of the coupling subassembly is improved.

[0035] The invention also relates, according to another aspect, to a motor vehicle differential comprising: - a main assembly capable of being driven by an electric motor;

[0036] - a coupling subassembly incorporating all or part of the characteristics as previously mentioned, in which the main assembly and the coupling subassembly are rotationally mobile relative to each other around the main axis of rotation X; and - a coupling device comprising an axial coupling slider fixed in rotation to the main assembly, the axial coupling slider being axially movable relative to the main assembly between:

[0037] - a coupled position in which the axial coupling slider is coupled with the coupling ring to transmit torque between the main assembly and the coupling sub-assembly and;

[0038] - a disengaged position in which the axial coupling slider and the The coupling crowns are uncoupled from each other.

[0039] This type of differential equipped with a coupling device makes it possible to interrupt the transmission of torque within the transmission chain of the motor vehicle.

[0040] Preferably, the axial coupling slider can be an annular component comprising an axially oriented toothing which is arranged to mesh with a complementary coupling toothing, axially oriented and formed on one of the bases of the cylindrical body of the coupling ring so as to form a dog clutch coupling device.

[0041] Advantageously, the axial coupling slider can be an annular component comprising an external spline arranged to mesh with the main assembly; the external spline and the axially oriented teeth form the annular portion of said component. For example, the external spline and the axially oriented teeth can be contiguous.

[0042] Preferably, the main assembly may include a housing forming a cavity arranged to receive the coupling sub-assembly, the housing supporting on its external periphery a gear for transmitting torque.

[0043] Advantageously, the housing can support on the cavity entrance an internal groove arranged to mesh with the external groove of the axial coupling slider.

[0044] Preferably, the annular part of the axial coupling slider can be inserted into the cavity of the housing.

[0045] Advantageously, the cavity of the housing can be a cylindrical bore which surrounds the coupling ring and the rods of the coupling subassembly.

[0046] According to one embodiment of the invention, the coupling device may include an actuating sleeve bearing on the axial coupling slider which is arranged to move the axial coupling slider between the coupled and uncoupled positions by means of an actuating fork.

[0047] Advantageously, the actuating sleeve may include an annular groove suitable for receiving the ends of the actuating fork.

[0048] According to another embodiment of the invention, the coupling device may include an electromagnetic actuator which is arranged to move the axial coupling slider axially relative to the main assembly between the coupled and uncoupled positions by means of a pusher piston, and also an elastic return device partially fixed on the axial coupling slider and which is arranged to deform elastically during the axial movement of the axial coupling slider.

[0049] Other features and advantages of the invention are highlighted by the following description of non-limiting examples of implementation of the various aspects of the invention. Brief description of the figures

[0050] The invention will be better understood, and other objects, details, features and advantages thereof will become more apparent from the following description of several particular embodiments of the invention, given solely by way of illustration and not limitation, with reference to the accompanying drawings.

[0051] [Fig-1] Fig. 1 is an overall, cross-sectional view of a differential equipped with a coupling sub-assembly according to a first embodiment.

[0052] [Fig.2] The [Fig.2] is an exploded view of the differential of the [Fig.1].

[0053] [Fig. 3] Fig. 3 is an isometric view of the axial coupling slider of the dif ferrentiel of the [Fig.l].

[0054] [Fig.4] The [Fig.4] is an isometric view of the differential coupling ring of the [Fig.1].

[0055] [Fig.5a] The [Fig.5a] is a cross-sectional view of the coupling subassembly of the [Fig.1].

[0056] [Fig.5b] The [Fig.5b] is a cross-sectional view of the coupling sub-assembly of the [Fig.l] according to an assembly variant.

[0057] [Fig.5c] The [Fig.5c] is a cross-sectional view of the coupling sub-assembly of the [Fig.l] according to another assembly variant.

[0058] [Fig.6] The [Fig.6] is an exploded view of a differential equipped with a coupling sub-assembly according to a second embodiment.

[0059] [Fig.7] The [Fig.7] is a cross-sectional view of the coupling subassembly of the [Fig.6].

[0060] [Fig.8] The [Fig.8] is a cross-sectional view of a coupling subassembly according to a third embodiment.

[0061] [Fig.9] The [Fig.9] is a cross-sectional view of a coupling subassembly according to a fourth embodiment. Description of the implementation methods

[0062] 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 principal axis of rotation X of the transmission system determining the "axial" orientation and, from the inside out and away from said axis, the "circumferential" orientation is directed orthogonally to the principal axis of rotation X and orthogonally to the radial direction.

[0063] Figures 1 to 5a illustrate a transmission system 1 according to a first embodiment. The transmission system here is a differential which is used, in a A transmission system of a motor vehicle, designed to transmit and distribute torque from a combustion or electric motor (not shown) to two axle shafts 2, 3 of a motor vehicle axle. Such a transmission system may, for example, be part of a secondary transmission system capable of transmitting torque from a secondary motor of the motor vehicle, such as an electric motor, to a front or rear axle, while a primary transmission system is capable of transmitting torque from a main motor, such as a combustion engine, to the axle shafts of another axle of the vehicle. The transmission system includes, in particular, a speed reducer kinematically linked to the electric motor and in which the differential is integrated.

[0064] The differential 1 comprises a main assembly 20, movable in rotation about the main axis of rotation X, and intended to be driven by a motor, such as an electric motor not shown, a coupling sub-assembly 10, also movable in rotation about the main axis of rotation X and intended to drive the wheel shafts 2, 3, and a coupling device 40 capable of selectively coupling or uncoupling the main assembly 20 and the coupling sub-assembly 10.

[0065] The main assembly 20 comprises a gear 27 which is intended to be driven by the motor via a reduction gear train 60, shown here schematically. This main assembly 20 also includes a housing 28 which is rotationally fixed to the gear 27, the housing 28 and the gear 27 being attached by means of assembly screws 25. The housing 28 is shown here as a single unit, but could be composed of several parts fixed together. A cover 29 closes the differential 1. The cover 29 is fitted into the housing 28 and consequently is rotationally fixed to the housing 28. The housing 28 supports a bearing for the rotation of the wheel shaft 3, while the cover 29 supports a bearing for the rotation of the wheel shaft 2.

[0066] The coupling sub-assembly 10 includes an annular coupling ring 11 which is guided in rotation, around the main axis of rotation X, inside the housing 28. To do this, the housing 28 includes an internal cylindrical portion cooperating with an external surface 11c of the coupling ring 11 in order to guide it in rotation relative to the housing 28. This external surface 11c is mainly cylindrical. The coupling subassembly 10 further comprises four satellite gears 14, 14a, 15, 15a visible in [Fig. 1], which are rotatably mounted on the coupling ring 11 about two secondary axes Z, Z' perpendicular to the main axis of rotation X. Each of the four satellite gears 14, 14a, 15, 15a has a bevel gear that meshes with a complementary bevel gear of two planetary gears 16, 17. The two planetary gears The planetary gears 16, 17 are mobile in rotation around the main axis of rotation X and are each rotationally fixed to one of the two wheel shafts 2, 3. The coupling ring 11, the satellite gears 14, 14a, 15, 15a and the planetary gears 16, 17 form a differential allowing the two wheel shafts 2, 3 to rotate at different speeds.

[0067] Furthermore, the transmission system 1 includes a coupling device 40 which, in the coupled position, allows a torque to be transmitted between the main assembly 20 and one of the components of the coupling sub-assembly 10, here the coupling ring 11. Thus, the transmission system allows, when the coupling device 40 is in the coupled position, the transmission of torque from the motor to the wheel shafts 2, 3 by exercising the function of a differential allowing different rotational speeds of the wheel shafts 2, 3.

[0068] The coupling ring 11 has a cylindrical body lia concentric to the main axis of rotation X and a complementary coupling toothing 11b formed on the cylindrical body suitable for coupling to a component of the main assembly 20.

[0069] The coupling device 40 comprises an axial coupling slider 21 which is rotationally fixed to the housing 28 while being axially movable along the main axis of rotation X relative to said housing 28. The axial coupling slider 21 is movable between an uncoupled position, shown in [Fig. 1], and a coupled position. In the uncoupled position, the axial coupling slider 21 is uncoupled from the coupling ring 11 so that torque transmission is interrupted between the main assembly 20 and the coupling sub-assembly 10. Conversely, in the coupled position, the axial coupling slider 21 is coupled to the coupling ring 11, which allows torque transmission between the main assembly 20 and the coupling sub-assembly 10.

[0070] In the embodiment shown, the coupling device 40 is a dog clutch device.

[0071] As shown in [Fig. 3], the axial coupling slider 21 is an annular component comprising:

[0072] - an external groove 21a arranged to mesh with the main assembly 20, and;

[0073] - an axially oriented toothing 21b which is arranged to mesh with a The coupling teeth 11b, complementary to the coupling ring 11,

[0074] the external spline 21a and the axially oriented teeth 21b form the annular portion 21c of said component. This allows the axial coupling slider 21 to be rotationally fixed to the housing 28 while permitting relative axial movement between the axial coupling slider 21 and the housing 28.

[0075] In this first embodiment of the invention, the external groove 21a and the axially oriented teeth 21b are contiguous. In particular, the radially oriented bottom of the external groove 21a defines a circumferential surface 21c and the axially oriented bottom of the teeth 21b defines a flat surface 21d; the two surfaces 21c, 21d have a circular edge 21e in common.

[0076] In the example of [Fig. 3], the bottom of the external groove 21a communicates di directly with the bottom of the axially oriented tooth 21b. This facilitates the production of the teeth by machining.

[0077] The housing 28 forms a cavity 28b arranged to receive a gear train and supports on its outer periphery 28a the torque transmission gear 27. At the entrance of the cavity 28b, the housing 28 supports an internal spline 28c arranged to mesh with the external spline 21a of the axial coupling slider 21. The internal spline 28c is, for example, a straight spline with a geometry complementary to the geometry of the external spline 21a. Alternatively, the internal spline 28c may be a series of recesses adapted to receive the external spline 21a.

[0078] In addition, the coupling ring 11 includes a complementary, axially oriented coupling tooth 11b arranged to mesh with the axially oriented tooth 21b of the axial coupling slider 21 when the coupling device is in the coupled position. As illustrated in [Fig. 4], the complementary, axially oriented coupling tooth 11b is, for example, a series of grooves having a geometry complementary to the geometry of the axially oriented tooth 21b of the axial coupling slider 21. The complementary, axially oriented coupling tooth 11b may comprise teeth or grooves formed on one of the bases of the cylindrical body 1 of the coupling ring perpendicular to the main axis of rotation X.

[0079] As illustrated in Figures 1 and 2, the coupling device 40 comprises an actuating sleeve 50 bearing on the axial coupling slider 21, which is arranged to move the axial coupling slider 21 between the coupled and uncoupled positions by means of an actuating fork 70, shown schematically. The actuating sleeve 50 bears on studs 21g formed on the annular portion 21c of the axial coupling slider 21. The studs 21g pass through holes formed in the closing cover 29. The actuating sleeve 50 includes, in particular, an annular groove 51 adapted to receive the ends of the actuating fork 70.

[0080] In an alternative variant not shown, the differential 1 may include an electromagnetic actuator for axially moving the axial coupling slider 21 relative to the housing 28. The electromagnetic actuator then comprises a solenoid and an axially movable pushrod piston, as well as an elastic return device. allowing the axial coupling slider 21 to be returned to the uncoupled position.

[0081] We will now describe, with reference to [Fig. 5a], the assembly of the coupling sub-assembly 10 and in particular the retention of the planetary gears 14, 14a, 15, 15a within the cylindrical body 1a. In the first embodiment, the four planetary gears 14, 14a, 15, 15a are held in position inside the coupling ring 11 by means of rods 12 and more particularly four rods. Each satellite gear 14, 14a, 15, 15a pivots around a rod 12 which passes through the cylindrical body of the coupling ring along a second axis Z. Each of the rods is held in position relative to the coupling ring by a locking means 30 which acts in the direction of the second axis Z, the locking means is a screw assembly which is oriented coaxially with respect to the second axis Z.The coupling ring 11 includes four through-holes 1 If through the cylindrical body into which the rods 12 are inserted. The through-holes 1 If open into the flats 1 Id. .

[0082] As illustrated in [Fig. 5a], the screw assembly is achieved indirectly by screwing rods 12 into an assembly nut 31. The rods 12 are inserted into the through holes 1 If in the cylindrical body. The assembly nut 31 includes drilled and tapped holes associated with each of the rods, and each of the drilled and tapped axes is perpendicular to the main axis of rotation X. In this example, four rods 12 are assembled in the assembly nut 31.

[0083] The rods 12 are identical and each comprises a cylindrical portion 12b, a threaded end 12c and a shoulder 12a. The shoulder 12a generally includes a recess allowing the insertion of a screwdriver bit.

[0084] The threaded ends 12c of the rods 12 are screwed into the assembly nut 31, and the shoulder 12a of the rod 12 bears against the external surface 11 of the cylindrical body. Thus, each rod is placed under tension by the tightening of the screw assembly and applies a mechanical preload to the cylindrical body 11 along the second axis Z via the shoulder 12a. The arrows shown in Figure 5a indicate the direction of the forces applied by the rods 12 on the coupling ring 11.

[0085] The assembly nut 31 takes up all the tensile forces exerted by the rods 12.

[0086] The assembly nut 31 includes a central bore 32, coaxial with the main axis of rotation X and suitable for receiving the end of a wheel shaft 3.

[0087] In this first embodiment, the cylindrical portion 12b of the rod rests on an annular surface 31d formed on the assembly nut and the shoulder 12a of the rod rests on the flat 11d formed on the cylindrical body. Lindrique. The two supports are simultaneous.

[0088] In an assembly variant illustrated in [Fig.5b], only the shoulder 12a of the rod is supported on the flat 1 Id formed on the cylindrical body 11. There is a reduced axial clearance Jl, on the order of a few tenths of a millimeter, between the cylindrical portion 12b of the rod and the annular surface 31d formed on the assembly nut 31. Thus, each rod 12 is put under tension under the effect of the tightening of the screwed assembly and applies a mechanical preload on the cylindrical body along the second axis Z via the shoulder 12a.

[0089] In another assembly variant illustrated in [Fig. 5c], only the cylindrical portion 12b of the rod bears against an annular surface 31d formed on the assembly nut 31. There is a reduced axial clearance J2, on the order of a few tenths of a millimeter, between the shoulder 12a of the rod and the flat 11d formed on the cylindrical body. Thus, each rod 12 will be under tension during the radial expansion of the coupling ring under the effect of the actuation forces of the planetary gears, which tend to deform the cylindrical body 11a in the direction of the second axis Z. Beyond a certain controlled deformation of the cylindrical body 11a, on the order of a few tenths of a millimeter, the rods 12 will apply a mechanical preload to the cylindrical body along the second axis Z via the shoulder 12a.

[0090] All three of these assembly variants make it possible to increase the rigidity of the coupling ring 11 and have the advantage of transmitting high torques within a differential 1 placed between the electric or thermal motor and the wheels of the motorized vehicle.

[0091] We will now describe, with reference to figures 6 and 7, a second embodiment of the invention, which differs from the previous one by a different arrangement of the rod 12 within the coupling sub-assembly 10.

[0092] The coupling sub-assembly 10 of this second embodiment comprises an annular coupling ring 11 which is guided in rotation, around the main axis of rotation X, inside the housing 28 of the differential 1. The coupling sub-assembly 10 in this case comprises only two satellite gears 14, 14a, visible in [Fig. 6], which are mounted for rotation on the coupling ring 11 about a second axis Z, perpendicular to the main axis of rotation X. The two satellite gears 14, 14a each have a bevel gear which meshes with a complementary bevel gear of two planetary gears 16, 17. The two planetary gears 16, 17 are free to rotate about the main axis of rotation X and are each rotationally fixed to one of the two wheel shafts 2, 3.The coupling ring 11, the satellite gears 14, 14a and the planetary gears 16, 17 form a differential allowing the two. wheel shafts 2, 3 to rotate at different speeds.

[0093] In this second embodiment, the two planetary gears 14, 14a, are held in position inside the coupling ring 11 by means of a single rod 12 and an end screw 35. Each planetary gear 14, 14a pivots about a single rod 12 which passes through the cylindrical body of the coupling ring 11 along a second axis Z. The rod 12 is held in position relative to the coupling ring 11 by a locking means 30 which acts in the direction of the second axis Z; the locking means is a screw assembly which is oriented coaxially with respect to the second axis Z.

[0094] As illustrated in [Fig. 7], the rod 12 has a shoulder 12a at one end which bears against the external surface 1le of the cylindrical body 1la and a cylindrical portion 12b. A drilled and tapped hole 12f is made at the end of the rod into which the end screw 35 is inserted. The rod 12 is tensioned by tightening the end screw and applies a mechanical preload to the cylindrical body along the second axis Z via the shoulder. In this way, the rod helps to transfer the actuation forces of the satellite gears to the cylindrical body and creates an internal loop of forces within the coupling subassembly.

[0095] As illustrated in [Fig.7], the screwed assembly is made directly by screwing a single rod 12 and an end screw 35. In this second embodiment, the shoulder of the rod and the end screw are supported on flats provided on the cylindrical body 1 of the coupling ring 11.

[0096] Alternatively, the end screw 35 can be replaced by an end nut. The rod 12 then comprises a cylindrical portion, a threaded end, and a shoulder. The end nut and the threaded end then form the locking means 30.

[0097] Figure 8 illustrates a third embodiment which differs from the second embodiment by the use of a rod 12 in the form of an assembly stud and two end screws 35. Drilled and tapped holes are made at each end of the rod 12 into which the end screws 35 are inserted. The end screws 35 and the drilled and tapped holes then form the locking means 30. The screw assembly is made directly by screwing together a single rod 12 and two end screws 35.

[0098] The rod 12 has a cylindrical portion 12b inserted into two through-holes 1 If in the cylindrical body 1 la. The rod 12 is tensioned by tightening the two end screws 35 and applies a mechanical preload to the cylindrical body along the second axis Z via the shoulder. In this way, the rod 12 helps to transfer the actuation forces of the satellite gears to the cylindrical body and creates an internal loop of forces within the coupling subassembly.

[0099] Alternatively, the end screws 35 can be replaced by end nuts. The rod 12 then comprises a cylindrical portion and two threaded ends. The end nuts and the threaded ends then form the locking means 30.

[0100] We will now describe, with reference to [Fig.9], a fourth embodiment of the invention, which differs from the first embodiment by a different arrangement of the rod 12 within the coupling sub-assembly 10.

[0101] The coupling sub-assembly 10 of this fourth embodiment comprises an annular coupling ring 11 which is guided in rotation, around the main axis of rotation X, inside the housing 28 of the differential 1. The coupling sub-assembly 10 in this case comprises only two planetary gears 14, 14a, visible in [Fig. 9], which are mounted for rotation on the coupling ring 11 about a second axis Z, perpendicular to the main axis of rotation X. The two planetary gears 14, 14a each have a bevel gear which meshes with a complementary bevel gear of two planetary gears 16, 17. The two planetary gears 16, 17 are free to rotate about the main axis of rotation X and are each rotationally fixed to one of the two wheel shafts 2, 3.The coupling ring 11, the satellite gears 14, 14a and the planetary gears 16, 17 form a differential allowing the two wheel shafts 2, 3 to rotate at different speeds.

[0102] In this fourth embodiment, the two planetary gears 14, 14a, are held in position inside the coupling ring 11 by means of a single rod 12. Each planetary gear 14, 14a pivots about the rod 12 which passes through the cylindrical body 1 of the coupling ring along a second axis Z. The rod 12 is held in position relative to the coupling ring by a locking means 30 which acts in the direction of the second axis Z; the locking means is a riveted assembly which is oriented coaxially with respect to the second axis Z.

[0103] As illustrated in [Fig. 9], the rod 12 has a shoulder 12a at one end and a flange 12d at the other end, which bear against the external surface 1 of the cylindrical body 11. The rod is placed under tension by the riveting and applies a mechanical preload to the cylindrical body along the second axis Z via the shoulder 12a and the flange 12b. In this way, the rod helps to transfer the actuation forces of the satellite gears to the cylindrical body and provides an internal loop of forces within the coupling subassembly.

[0104] The shoulder 12a and the ferrule 12d of the rod are inscribed in the cylindrical external volume of the coupling ring.

[0105] Although the invention has been described in connection with several particular embodiments, it is clearly evident that it is by no means limited to them and that it includes all technical equivalents of the means described as well as their combinations if these fall within the scope of the invention, as defined by the claims.

[0106] In the claims, any reference sign in parentheses shall not be interpreted as a limitation of the claim.

Claims

Demands

1. Coupling sub-assembly (10) for motor vehicle differential comprising: - a coupling ring (11) having a cylindrical body (lia) with a main axis of rotation (X) and a coupling toothing (11b) formed on the cylindrical body suitable for coupling onto an axial coupling slider (21), - at least two satellite gears (14, 14a, 15, 15a) which are mounted for rotation on the coupling ring (11) about a second axis (Z, Z') perpendicular to the main axis of rotation (X);- and two planetary gears (16, 17) which are free to rotate about the main axis of rotation (X), each planetary gear is meshed with the satellite gears (14, 14a, 15, 15a) and intended to be rotationally fixed to a wheel shaft (2, 3) of the motor vehicle, in which the satellite gears (14, 14a, 15, 15a) pivot about at least one rod (12) which passes through the cylindrical body (1a) of the coupling ring (11) along the second axis (Z, Z') and at least one rod (12) is held in position relative to the coupling ring by a locking means (30) which acts in the direction of the second axis (Z, Z'), at least one rod (12) being supported on an external surface (11c) of the cylindrical body.;

2. Coupling subassembly (10) according to claim 1, wherein the locking means (30) of at least one rod is a screw assembly which is oriented coaxially with respect to the second axis (Z, Z').

3. Coupling sub-assembly (10) according to the preceding claim, wherein each satellite gear pivots about a separate rod, each rod (12) has a shoulder (12a) which bears against the external surface (11c) of the cylindrical body, and each rod is put under tension by the tightening of the screwed assembly and applies a mechanical preload on the cylindrical body along the second axis (Z, Z') via the shoulder (12a).

4. Coupling subassembly (10) according to the preceding claim, wherein the shoulder (12a) of each rod is inscribed in the cylindrical external volume of the coupling ring (11).

5. Coupling subassembly (10) according to claim 3 or 4, wherein the shoulder (12a) of each rod bears against a flat (1 Id) formed on the external surface (11c) of the cylindrical body (lia).

6. Coupling subassembly (10) according to any one of claims 2 to 5, wherein the screw assembly is made directly by screwing rods (12) together or by screwing a single rod (12) and end screw (35), or the screw assembly is made indirectly by screwing rods (12) into an assembly nut (31).

7. Coupling subassembly (10) according to the preceding claim, in the case of an indirectly screwed assembly, at least two rods (12) are screwed into the assembly nut (31), the assembly nut (31) comprising drill-tap holes (32) associated with each of the rods (12) and each of the drill-tap axes (32) is perpendicular to the main axis of rotation (X).

8. Coupling subassembly (10) according to the preceding claim, wherein the assembly nut (31) comprises a central bore (33), coaxial with the main axis of rotation (X) and suitable for receiving the end (3a) of a wheel shaft (3).

9. Coupling subassembly (10) according to claim 1, wherein the locking means (30) of at least one rod is a riveted assembly which is oriented coaxially with respect to the second axis (Z, Z').

10. Motor vehicle differential (1) comprising: - a main assembly (20) capable of being driven by an electric motor; - a coupling subassembly (10) according to any one of the preceding claims, wherein the main assembly (20) and the coupling subassembly (10) are rotationally movable relative to each other about the main axis of rotation (X); and - a coupling device (40) comprising an axial coupling slider (21) rotationally fixed to the main assembly (20), the axial coupling slider (21) being axially movable relative to the main assembly (20) between: - a coupled position in which the axial coupling slider (21) is coupled with the coupling ring (11) to transmit torque between the main assembly (20) and the coupling subassembly (10) and;- a disengaged position in which the axial coupling slider (21) and the coupling ring (11) are disengaged from each other.;

11. Differential (1) of a motor vehicle according to the preceding claim, wherein the axial coupling slider (21) is an annular component comprising an axially oriented tooth (21b) which is arranged to mesh with a complementary coupling tooth (11b), axially oriented and formed on one of the bases of the cylindrical body (1la) of the coupling ring (11) so as to form a dog clutch coupling device (40).

12. Motor vehicle differential (1) according to the preceding claim, wherein the axial coupling slider (21) is an annular component comprising an external spline (21a) arranged to mesh with the main assembly (20), the external spline (21a) and the axially oriented teeth (21b) form the annular part (21c) of said component.

13. Motor vehicle differential (1) according to claim 10, wherein the main assembly (20) comprises a housing (28) forming a cavity (28b) arranged to receive the coupling sub-assembly (10), the housing (28) supporting on its external periphery (28a) a gear (27) for torque transmission.

14. Motor vehicle differential (1) according to the combination of claims 12 and 13, wherein the housing (28) supports on the inlet of the cavity (28b) an internal groove (28c) arranged to mesh with the external groove (21a) of the axial coupling slider (21).

15. Motor vehicle differential (1) according to claim 12, wherein the annular part (21c) of the axial coupling slider (21) is inserted into the cavity (28b) of the housing (28).

16. Motor vehicle differential (1) according to any one of claims 10 to 15, wherein the coupling device (40) comprises an actuating sleeve (50) bearing on the axial coupling slider (21) which is arranged to move the axial coupling slider (21) between the coupled and uncoupled positions by means of an actuating fork (70).

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