Coupling subassembly for motor vehicle differential

Abstract

The invention relates to a coupling subassembly (10) for a motor vehicle differential comprising: - a coupling crown (11) having a cylindrical body (11a) with a main axis of rotation (X) and a coupling toothing formed on the cylindrical body capable of coupling to an axial coupling slider (21), - at least two satellite gears (14, 14a, 15, 15a) which are rotatably mounted on the coupling crown (11) about a second axis (Z, Z') perpendicular to the main axis of rotation (X);- and two planetary gears (16, 17) which are rotatable about the main rotation axis (X), each planetary gear is engaged with the satellite gears (14, 14a, 15, 15a) and intended to be integral in rotation with a wheel shaft (2, 3) of the motorized vehicle, in which the satellite gears pivot about a rod (12) which passes through the cylindrical body of the coupling crown along the second axis (Z, Z'). Figure for the abstract: Fig. 2;

Description

Title of the invention: Coupling subassembly for a motor vehicle differential Technical field

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

[0002] It relates more particularly to a differential type transmission system intended to transmit and distribute a torque coming from an electric or thermal motor to two wheel shafts of an axle of the vehicle. 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 A1 discloses a differential type transmission system. The transmission system comprises a differential housing rotatable about an axis A which is equipped with a toothed wheel driven by a vehicle engine. Inside the housing are housed a coupling ring gear guided in rotation in the housing, two planetary gears which are mounted in rotation on the coupling ring gear about an axis B perpendicular to the axis A, and two planetary gears which each mesh with the two planetary gears and which are each integral in rotation with a wheel shaft. Used in a transmission chain of a motor vehicle, the differential type transmission system allows the drive wheels to rotate at different speeds when passing through a bend: the wheels located on the outside of the bend rotate faster than those located on the inside.

[0004] Furthermore, the transmission system comprises a coupling device which allows either the transmission system housing to be coupled to the coupling ring gear in order to allow transmission and distribution of torque from the engine to the two wheel shafts of the axle or to uncouple them in order 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 part having an annular portion arranged outside the housing and projecting elements which extend from the annular portion and pass through of orifices provided in the housing, which allows the first coupling part and the housing to be secured in rotation. The second coupling part of the coupling device comprises the coupling ring. The projecting elements of the first coupling part comprise teeth intended to cooperate with complementary grooves provided 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 transmission of the torque coming from the electric motor is done by teeth formed at the end of the coupling ring and projecting elements. This transmission by teeth is therefore only distributed over a few angular sectors, which limits the number of teeth meshing with the complementary teeth arranged on the coupling ring. The torque transmission capacity of such a transmission system is limited.

[0006] Such a transmission system is also not fully satisfactory in terms of internal deformation of the components, in particular the coupling crown when it transmits the torque to the wheel shafts. The coupling crown is a large diameter component crossed from one side to the other by a rod serving as a support for the satellite gears. This coupling crown is deformed under the effect of the actuating forces of the satellite gears which tend to deform the cylindrical body of the coupling crown in the direction of the rod. These deformations are detrimental to the precision of the teeth of the dog clutch device. In addition, the durability of the differential gears will be affected by wear of the meshing teeth due to the deformations undergone by the coupling crown. Summary

[0007] An idea at the basis of the invention is to propose a transmission system with high torque transmission capacity whose assembly would be simplified and whose component called "coupling crown" 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 crown having a cylindrical body with an axis of main rotation X and a coupling tooth formed on the cylindrical body capable of coupling on an axial coupling slider,

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

[0011] - and two planetary gears which are movable in rotation around the axis of main rotation X, each planetary gear is meshed with the sa- gears tellites and intended to be integral in rotation with a wheel shaft of the motorized vehicle,

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

[0013] In this coupling subassembly, the support of the rod(s) on the external surface of the cylindrical body increases the rigidity of the coupling crown 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] The at least one rod participates in the absorption of the actuating forces of the satellite gears with the cylindrical body and achieves an internal looping of the forces within the coupling subassembly. This limits the radial expansion of the coupling ring under the effect of the actuating 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 comprise bearing surfaces for the at least one rod made in the form of a flat, a concave surface or any other shape capable of receiving the support of a rod. The flat surface of the flat improves the precision of the tightening torque applied to the rod.

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

[0017] Preferably, each satellite gear can pivot around a separate rod, each rod has a shoulder which bears on the external surface of the cylindrical body, and each rod is put under tension under the effect of the tightening of the screwed assembly and applies a mechanical prestress to the cylindrical body along the second axis Z, Z' via the shoulder. In this way, each rod participates in taking up the actuating forces of the satellite gears and achieves an internal looping of the forces within the coupling subassembly.

[0018] Advantageously, the shoulder of each rod can be inscribed in the cylindrical external volume of the coupling crown. 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 may bear on a flat formed on the external surface of the cylindrical body. The coupling subassembly has the advantage of being radially compact.

[0020] Advantageously, the screwed assembly can be achieved directly by screwing rods together or by screwing a single rod and end screws, or the screwed assembly can be achieved 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 drilling-tappings associated with each of the rods and each of the drilling-tapping axes is perpendicular to the main rotation axis X. For example, four rods are assembled in the assembly nut.

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

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

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

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

[0026] Preferably, the assembly nut may comprise 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 comprise an axial bearing surface for each rod, each bearing surface is of any 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 on the external surface of the cylindrical body of the coupling ring, a cylindrical portion and a drilling-tapping made at the end of the rod into which the end screw is introduced.

[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 drilling-tapping made at the end of the rod into which the threaded end of the first rod is introduced.

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

[0031] Preferably, the satellite gears can pivot around a single rod, the rod has a shoulder at one end and a rivet at the other end which come to bear on the external surface of the cylindrical body, and the rod is put under tension under the effect of riveting and comes to apply a mechanical prestress on the cylindrical body along the second axis Z by means of the shoulder and the rivet. In this way, the rod participates in the absorption of the actuating forces of the satellite gears with the cylindrical body and achieves an internal looping of the forces within the coupling subassembly.

[0032] Advantageously, the shoulder and the rivet of the rod can be inscribed in the cylindrical external volume of the coupling crown. The coupling subassembly has the advantage of being radially compact.

[0033] Alternatively, the 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 the at least one rod may be a welded assembly, for example electron beam welding, fixing the rod and the coupling ring or fixing the rod and the assembly nut. A force for pressing the rod onto 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 pinions under load, which contributes to the absorption of the actuating forces of the satellite gears within the coupling subassembly. The durability of the coupling subassembly is improved.

[0035] The invention also relates, according to another of its aspects, to a motorized 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 mentioned above, wherein the main assembly and the coupling subassembly are rotatable relative to each other about the main rotation axis X; and - a coupling device which comprises an axial coupling slider integral in rotation with 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 for transmitting torque between the main assembly and the coupling subassembly and;

[0038] - an uncoupled position in which the axial coupling slider and the coupling crown 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 motorized vehicle.

[0040] Preferably, the axial coupling slider may be an annular-shaped component comprising axially oriented teeth which are arranged to mesh with complementary axially oriented coupling teeth 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 may be an annular-shaped component comprising an external spline arranged to mesh with the main assembly, the external spline and the axially oriented toothing forming the annular portion of said component. For example, the external spline and the axially oriented toothing may be contiguous.

[0042] Preferably, the main assembly may comprise a housing forming a cavity arranged to receive the coupling sub-assembly, the housing supporting on its external periphery a torque transmission toothed wheel.

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

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

[0045] Advantageously, the cavity of the housing may 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 comprise 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 sheath may comprise an annular groove capable of receiving the ends of the actuating fork.

[0048] According to another embodiment of the invention, the coupling device may comprise 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 to the axial coupling slider and which is arranged to deform elastically during the axial movement of the axial coupling slider.

[0049] Other characteristics and advantages of the invention are highlighted by the following description of non-limiting examples of embodiments of the different aspects of the invention. Brief description of the figures

[0050] The invention will be better understood, and other aims, details, characteristics and advantages thereof will appear more clearly during the following description of several particular embodiments of the invention, given solely for illustrative and non-limiting purposes, with reference to the appended drawings.

[0051] [Fig-1] [Fig.l] is an overall view, in section, of a differential equipped with a coupling subassembly according to a first embodiment.

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

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

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

[0055] [Fig.5a] [Fig.5a] is a sectional view of the coupling subassembly of [Fig.l].

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

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

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

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

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

[0061] [Fig.9] [Fig.9] is a sectional view of a coupling subassembly according to a fourth embodiment. Description of the embodiments

[0062] In the description and the claims, the terms "external" and "internal" as well as the orientations "axial" and "radial" will 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 main axis of rotation X of the transmission system determining the "axial" orientation and, from the inside to the outside moving away from said axis, the "circumferential" orientation is directed orthogonally to the main 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 transmission chain of a motorized vehicle, for transmitting and distributing torque from a thermal or electric engine, not shown, to two wheel shafts 2, 3 of an axle of a motor vehicle. Such a transmission system may, for example, be part of a secondary transmission chain capable of transmitting torque from a secondary engine of the motorized vehicle, such as an electric motor, to a rear or front axle of a vehicle while a primary transmission chain is capable of transmitting torque from a main engine, for example a thermal engine, to the wheel shafts of another axle of the vehicle. The transmission chain comprises 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, rotatable about the main rotation axis X, and intended to be driven by a motor, such as an electric motor not shown, a coupling subassembly 10, also rotatable about the main rotation axis 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 subassembly 10.

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

[0066] The coupling subassembly 10 comprises a coupling ring 11 of annular shape which is guided in rotation, around the main rotation axis X, inside the housing 28. To do this, the housing 28 comprises 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 planetary gears 14, 14a, 15, 15a visible in [Fig.l], which are rotatably mounted on the coupling crown 11 around two second axes Z, Z' perpendicular to the main rotation axis X. The four planetary gears 14, 14a, 15, 15a each comprise a bevel gear which meshes with a complementary bevel gear of two planetary gears 16, 17. The two planetary gears gears 16, 17 are rotatable around the main rotation axis X and are each integral in rotation with one of the two wheel axles 2, 3. The coupling crown 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 comprises a coupling device 40 which, in the coupled position, makes it possible to transmit a torque between the main assembly 20 and one of the components of the coupling subassembly 10, here the coupling crown 11. Thus, the transmission system makes it possible, when the coupling device 40 is in the coupled position, to transmit a torque from the engine to the wheel shafts 2, 3 by exercising the differential function allowing different rotation speeds of the wheel shafts 2, 3.

[0068] The coupling crown 11 has a cylindrical body 11a concentric with the main rotation axis X and a complementary coupling toothing 11b formed on the cylindrical body capable of coupling onto a component of the main assembly 20.

[0069] The coupling device 40 comprises an axial coupling slider 21 which is rotationally integral with the housing 28 while being axially movable along the main rotation axis 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 the transmission of torque is interrupted between the main assembly 20 and the coupling subassembly 10. On the contrary, in the coupled position, the axial coupling slider 21 is coupled to the coupling ring 11, which allows the transmission of torque between the main assembly 20 and the coupling subassembly 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-shaped 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 coupling teeth 11b complementary to the coupling crown 11,

[0074] the external groove 21a and the axially oriented teeth 21b form the annular part 21c of said component. This makes it possible to secure the axial coupling slider 21 in rotation to the housing 28 while allowing 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 toothing 21b are contiguous. In particular, the bottom of the radially oriented external groove 21a defines a circumferential surface 21c and the bottom of the axially oriented toothing 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 toothing 21b oriented axially. This makes it easier to obtain the teeth by machining.

[0077] The housing 28 forms a cavity 28b arranged to receive a gear train and supports on its external periphery 28a the torque transmission toothed wheel 27. On 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 of geometry complementary to the geometry of the external spline 21a. Alternatively, the internal spline 28c may be a succession of recesses capable of receiving the external spline 21a.

[0078] In a complementary manner, the coupling ring gear 11 comprises a complementary axially oriented coupling toothing 11b which is arranged to mesh with the axially oriented toothing 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 toothing 11b is for example a series of grooves having a geometry complementary to the geometry of the axially oriented toothing 21b of the axial coupling slider 21. The complementary axially oriented coupling toothing 11b may comprise teeth or grooves arranged on one of the bases of the cylindrical body 11a of the coupling ring gear 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 arranged on the annular part 21c of the axial coupling slider 21. The studs 21g pass through holes formed in the closing cover 29. The actuating sleeve 50 comprises in particular an annular groove 51 capable of receiving the ends of the actuating fork 70.

[0080] In a variant not shown, the differential 1 may comprise an electromagnetic actuator making it possible to axially move the axial coupling slider 21 relative to the housing 28. The electromagnetic actuator then comprises a solenoid and an axially movable push 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 subassembly 10 and in particular the holding of the satellite gears 14, 14a, 15, 15a within the cylindrical body 11a. In the first embodiment, the four satellite gears 14, 14a, 15, 15a are held in position inside the coupling crown 11 by means of rods 12 and more particularly four rods. Each satellite gear 14, 14a, 15, 15a pivots about a rod 12 which passes through the cylindrical body of the coupling crown along a second axis Z. Each of the rods is held in position relative to the coupling crown by a locking means 30 which acts in the direction of the second axis Z, the locking means is a screwed assembly which is oriented coaxially relative to the second axis Z.The coupling crown 11 comprises four passage orifices 1 If passing right through the cylindrical body into which the rods 12 are inserted. The passage orifices 1 If open into the flats 1 Id.

[0082] As illustrated in [Fig.5a], the screwed assembly is achieved indirectly by screwing rods 12 into an assembly nut 31. The rods 12 are inserted into the passage orifices 1 If of the cylindrical body. The assembly nut 31 comprises drilling-tappings associated with each of the rods and each of the drilling-tapping axes is perpendicular to the main rotation axis X. In this example, four rods 12 are assembled in the assembly nut 31.

[0083] The rods 12 are identical and each comprise a cylindrical portion 12b, a threaded end 12c and a shoulder 12a. The shoulder 12a generally comprises an imprint 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 on the external surface 11e of the cylindrical body. Thus, each rod is put under tension under the effect of the tightening of the screwed assembly and applies a mechanical prestress to the cylindrical body 11a along the second axis Z via the shoulder 12a. The arrows illustrated in FIG. 5a indicate the direction of the forces applied by the rods 12 to the coupling ring 11.

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

[0086] The assembly nut 31 comprises a central bore 32, coaxial with the main rotation axis X and capable of 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 provided on the assembly nut and the shoulder 12a of the rod rests on the flat 11d provided on the cylindrical body. lindic. The two supports are simultaneous.

[0088] In an assembly variant illustrated in [Fig.5b], only the shoulder 12a of the rod bears on the flat 11d provided on the cylindrical body 11. There is a reduced axial clearance Jl, of the order of a few tenths of a millimeter, between the cylindrical portion 12b of the rod and the annular surface 31d provided 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 prestress to 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 on an annular surface 31d provided on the assembly nut 31. There is a reduced axial clearance J2, of the order of a few tenths of a millimeter, between the shoulder 12a of the rod and the flat 11d provided on the cylindrical body. Thus, each rod 12 will be put under tension during the radial expansion of the coupling ring under the effect of the actuating forces of the satellite 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, of the order of a few tenths of a millimeter, the rods 12 will apply a mechanical prestress 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 crown 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] A second embodiment of the invention will now be described with reference to Figures 6 and 7, which differs from the previous one by a different arrangement of the rod 12 within the coupling subassembly 10.

[0092] The coupling subassembly 10 of this second embodiment comprises a coupling ring 11 of annular shape which is guided in rotation, around the main axis of rotation X, inside the housing 28 of the differential 1. The coupling subassembly 10 comprises in the present case only two planetary gears 14, 14a, visible in [Fig. 6], which are mounted in rotation on the coupling ring 11 around a second axis Z, perpendicular to the main axis of rotation X. The two planetary gears 14, 14a each comprise a bevel gear which meshes with a complementary bevel gear of two planetary gears 16, 17. The two planetary gears 16, 17 are rotatable around the main axis of rotation X and are each integral in rotation with one of the two wheel axles 2, 3.The coupling crown 11, the satellite gears 14, 14a and the planetary gears 16, 17 form a differential allowing the two. axle shafts 2, 3 to rotate at different speeds.

[0093] In this second embodiment, the two satellite 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 satellite 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 screwed assembly which is oriented coaxially relative to the second axis Z.

[0094] As illustrated in [Fig.7], the rod 12 has a shoulder 12a at one end which bears on the external surface 11e of the cylindrical body 11a and a cylindrical portion 12b. A drilling-tapping 12f is made at the end of the rod into which the end screw 35 is introduced. The rod 12 is put under tension under the effect of the tightening of the end screw and applies a mechanical prestress to the cylindrical body along the second axis Z via the shoulder. In this way, the rod participates in taking up the actuating forces of the satellite gears with the cylindrical body and achieves an internal looping of the 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 bear on flats provided on the cylindrical body 11a of the coupling crown 11.

[0096] Alternatively, the end screw 35 may 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] [Fig. 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. Drilling-tappings are made at each end of the rod 12 into which the end screws 35 are introduced. The end screws 35 and drilling-tappings then form the locking means 30. The screwed assembly is made directly by screwing a single rod 12 and two end screws 35.

[0098] The rod 12 has a cylindrical portion 12b inserted into two passage orifices 1 If of the cylindrical body 1 la. The rod 12 is put under tension under the effect of the tightening of the two end screws 35 and comes to apply a mechanical prestress on the cylindrical body along the second axis Z by means of the shoulder. In this way, the rod 12 participates in the absorption of the actuating forces of the satellite gears with the cylindrical body and achieves an internal looping of the 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 subassembly 10.

[0101] The coupling subassembly 10 of this fourth embodiment comprises a coupling ring 11 of annular shape which is guided in rotation, around the main axis of rotation X, inside the housing 28 of the differential 1. The coupling subassembly 10 comprises in the present case only two planetary gears 14, 14a, visible in [Fig. 9], which are mounted in rotation on the coupling ring 11 around a second axis Z, perpendicular to the main axis of rotation X. The two planetary gears 14, 14a each comprise a bevel gear which meshes with a complementary bevel gear of two planetary gears 16, 17. The two planetary gears 16, 17 are rotatable around the main axis of rotation X and are each integral in rotation with one of the two wheel axles 2, 3.The coupling crown 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 satellite gears 14, 14a are held in position inside the coupling ring 11 by means of a single rod 12. Each satellite gear 14, 14a pivots around the rod 12 which passes through the cylindrical body 11a 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 relative to the second axis Z.

[0103] As illustrated in [Fig.9], the rod 12 has a shoulder 12a at one end and a rivet 12d at the other end which come to bear on the external surface 11c of the cylindrical body 11, and the rod is put under tension under the effect of riveting and comes to apply a mechanical prestress on the cylindrical body along the second axis Z by means of the shoulder 12a and the rivet 12b. In this way, the rod participates in the absorption of the actuating forces of the satellite gears with the cylindrical body and achieves an internal looping of the forces within the coupling subassembly.

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

[0105] Although the invention has been described in connection with several particular embodiments, it is quite obvious that it is in no way limited thereto and that it includes all the 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 cannot be interpreted as a limitation of the claim.

Claims

Claims

1. Coupling subassembly (10) for a motor vehicle differential comprising: - a coupling crown (11) having a cylindrical body (11a) with a main axis of rotation (X) and a coupling toothing (11b) formed on the cylindrical body capable of coupling to an axial coupling slider (21), - at least two satellite gears (14, 14a, 15, 15a) which are rotatably mounted on the coupling crown (11) about a second axis (Z, Z') perpendicular to the main axis of rotation (X);- and two planetary gears (16, 17) which are rotatable about the main rotation axis (X), each planetary gear is engaged with the satellite gears (14, 14a, 15, 15a) and intended to be integral in rotation with a wheel shaft (2, 3) of the motorized vehicle, in which the satellite gears (14, 14a, 15, 15a) pivot about at least one rod (12) which passes through the cylindrical body (11a) of the coupling crown (11) along the second axis (Z, Z') and the at least one rod (12) is held in position relative to the coupling crown by a locking means (30) which acts in the direction of the second axis (Z, Z'), the at least one rod (12) bearing on an external surface (11c) of the cylindrical body.;

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

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

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

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

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

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

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

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

10. A motor vehicle differential (1) comprising: - a main assembly (20) capable of being driven by an electric motor; - a coupling sub-assembly (10) according to any one of the preceding claims, wherein the main assembly (20) and the coupling sub-assembly (10) are rotatable relative to each other about the main rotation axis (X); and - a coupling device (40) which comprises an axial coupling slider (21) integral in rotation with 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 a torque between the main assembly (20) and the coupling sub-assembly (10) and;- an uncoupled position in which the axial coupling slider (21) and the coupling ring (11) are uncoupled from each other.;

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

12. A motor vehicle differential (1) according to the preceding claim, wherein the axial coupling slider (21) is an annular-shaped component comprising an external spline (21a) arranged to mesh with the main assembly (20), the external spline (21a) and the axially oriented toothing (21b) forming the annular portion (21c) of said component.

13. A 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 outer periphery (28a) a toothed wheel (27) for transmitting torque.

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

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

16. A motor vehicle differential (1) according to 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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