TRANSMISSION SYSTEM COMPRISING A REDUCTION DEVICE AND A DIFFERENTIAL DRIVE DEVICE
20230115338 · 2023-04-13
Assignee
Inventors
Cpc classification
F16H2200/0021
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F16H2048/346
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F16H48/34
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F16H48/24
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F16H48/42
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
International classification
F16H37/08
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F16H48/34
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
Abstract
A motor vehicle transmission system includes a reduction device having at least an output shaft including a first gearwheel and a second gearwheel. A differential drive device is configured to distribute the torque from the reduction device to two half-shafts. The differential drive device includes a coupling device which, in a coupled position, transmits torque between a first element and a second element of the differential drive device, the coupling device further including an actuator. A radial plane, orthogonal to the axes X and W, passes through the first gearwheel and through the coupling device.
Claims
1. Transmission system for a motor vehicle, comprising: a reduction device comprising at least an output shaft which is rotationally mobile about an axis W, the output shaft comprising a first gearwheel and a second gearwheel which are positioned side-by-side along the axis W, the first gearwheel being intended to be rotationally driven by a motor; a differential drive device which is configured to distribute the torque from the reduction device to two half-shafts of an axle of the vehicle, the differential drive device comprising a first element and a second element, each of the first and second elements being rotationally mobile about an axis X, parallel to the axis W, the first element being equipped with a driving gearwheel which is in mesh with the second gearwheel of the output shaft, and the second element being intended to drive at least one of the half-shafts; the differential drive device comprising a coupling device which comprises a first coupling part which is secured, for conjoint rotation, to the first element and a second coupling part which is secured, for conjoint rotation, to the second element, the first coupling part being axially mobile with respect to the first element between a coupled position in which the first coupling part is coupled to the second coupling part to transmit torque between the first element and the second element, and an uncoupled position in which the first coupling part and the second coupling part are uncoupled from one another, the coupling device further comprising an actuator collaborating with the first coupling part in order to move same between the coupled position and the uncoupled position, a radial plane, orthogonal to the axes X and W and passing through the first gearwheel and through the coupling device.
2. Transmission system according to claim 1, wherein the actuator comprises: a frame arranged around the axis X, the frame being fixed axially and circumferentially to a casing of the transmission system; and a piston guided in axial translation inside the frame between a retracted position and a deployed position, said piston being arranged in such a way as to move the first coupling part from the uncoupled position towards the coupled position as the piston moves from the retracted position to the deployed position.
3. Transmission system according to claim 2, wherein the first gearwheel is positioned axially between the second gearwheel and a radial plane, orthogonal to the axis X and passing through an end wall of the frame.
4. Transmission system according to claim 2, wherein the piston is fixed in terms of rotation about the axis X and fixed axially to the first coupling part by a pivot connection allowing relative rotation about the axis X of the first coupling part with respect to the piston; and wherein the coupling device comprises a target which is fixed to the piston and which is intended to be positioned facing a sensor able to deliver a signal representative of the distance between the target and the sensor.
5. Transmission system according to claim 4, wherein, when considered in projection in a plane orthogonal to said axis X, the target is inscribed inside a first angular sector (α) of centre X, and the first gearwheel is inscribed inside a second angular sector (β) of centre X, the first angular sector (α) and the second angular sector (β) being distinct from one another.
6. Transmission system according to claim 4, having a plane in which the axis X is contained and which passes through the target and the first gearwheel.
7. Transmission system according to claim 2, wherein the frame has a recess formed in a region radially facing the first gearwheel.
8. Transmission system according to claim 2, wherein the piston comprises a body made of a ferromagnetic material and wherein the actuator comprises an electromagnet which is housed in the frame and is able to move the piston between the retracted position and the deployed position, and wherein the piston and the electromagnet are positioned respectively one inside the other or axially one beside the other.
9. Transmission system according to claim 1, wherein the first element comprises a differential case inside which the second coupling part is housed, the first coupling part comprising an interior portion which is housed inside the differential case, an exterior portion which is positioned outside the differential case and a plurality of connecting portions which axially connect the interior portion and the exterior portion of the first coupling part, each of the connecting portions passing through a corresponding through-opening made in the differential case.
10. Transmission system according to claim 9, wherein the second element comprises a supporting ring which is guided in rotation about the axis X inside the differential case, two planet pinions which are mounted to rotate on the supporting ring about an axis V perpendicular to the axis X, and two sun gears which are able to rotate about the axis X, are each in mesh with the two planet pinions and are each intended to be secured, for conjoint rotation, to a half-shaft.
11. Transmission system according to claim 10, wherein the first gearwheel and the second gearwheel of the output shaft of the reduction device are situated axially, along the axis X, on the same side of the axis V.
12. Transmission system according to claim 1, wherein the coupling and uncoupling zone of the coupling device is positioned kinematically upstream of the differential function of the differential drive device.
13. Transmission system according to claim 1, wherein the radial plane, orthogonal to the axes X and W and passing through the first gearwheel and through the coupling device, passes through the actuator.
14. Powertrain comprising an electric machine and a transmission system according to claim 1, the electric machine being coupled to an input member of the reduction device.
15. Transmission system according to claim 3, wherein the piston is fixed in terms of rotation about the axis X and fixed axially to the first coupling part by a pivot connection allowing relative rotation about the axis X of the first coupling part with respect to the piston; and wherein the coupling device comprises a target which is fixed to the piston and which is intended to be positioned facing a sensor able to deliver a signal representative of the distance between the target and the sensor.
16. Transmission system according to claim 5, having a plane in which the axis X is contained and which passes through the target and the first gearwheel.
17. Transmission system according to claim 3, wherein the frame has a recess formed in a region radially facing the first gearwheel.
18. Transmission system according to claim 3, wherein the piston comprises a body made of a ferromagnetic material and wherein the actuator comprises an electromagnet which is housed in the frame and is able to move the piston between the retracted position and the deployed position, and wherein the piston and the electromagnet are positioned respectively one inside the other or axially one beside the other.
19. Transmission system according to claim 2, wherein the first element comprises a differential case inside which the second coupling part is housed, the first coupling part comprising an interior portion which is housed inside the differential case, an exterior portion which is positioned outside the differential case and a plurality of connecting portions which axially connect the interior portion and the exterior portion of the first coupling part, each of the connecting portions passing through a corresponding through-opening made in the differential case.
20. Transmission system according to claim 4, wherein the frame has a recess formed in a region radially facing the first gearwheel.
Description
BRIEF DESCRIPTION OF THE FIGURES
[0054] The invention will be better understood, and other aims, details, features and advantages thereof will become clearer, from the following description of a plurality of particular embodiments of the invention, provided solely by way of nonlimiting illustration, with reference to the appended drawings.
[0055]
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DESCRIPTION OF THE EMBODIMENTS
[0063] In the description and the claims, the terms “external” and “internal” and the orientations “axial” and “radial” will be used to denote elements of the transmission system according to the definitions given in the description. By convention, the axis X of rotation of the differential case defines the “axial” orientation. The “radial” orientation is directed orthogonally to the axis X and from the inside towards the outside moving away from said axis.
[0064]
[0065] According to one embodiment, such a transmission system is intended for a hybrid vehicle. Thus, the transmission system is, for example, able to transmit a torque from an electric motor to a rear or front axle of the vehicle, while another transmission system, coupled to another motor/engine, such as a combustion engine, is able to generate a torque and transmit it between this other motor/engine and the two half-shafts of the other axle of the vehicle.
[0066] In the embodiment depicted, the reduction device 1 comprises three shafts, all visible in
[0067] As illustrated in
[0071] The first element 45 of the differential drive device 2 comprises a differential case 15, visible in
[0072] In connection with
[0073] The coupling device 20 is configured to selectively transmit torque between the differential case 15 and the supporting ring 19. Thus, when the coupling device 20 is in the coupled position, the transmission system allows torque to be transmitted between the motor and the half-shafts 3, 4, while performing a differential function to allow the half-shafts 3, 4 different rotational speeds. When the coupling device 20 is in the uncoupled position, transmission between the motor and the half-shafts 3, 4 is interrupted.
[0074] In another embodiment which has not been depicted, the coupling device is configured to couple the first element 45 to one of the two sun gears 23, 24. In such an embodiment, the supporting ring 19 is secured, for conjoint rotation, to the differential case 15 or else the two planet pinions 21, 22 are mounted to rotate directly on the differential case 15. Such a coupling device is therefore aimed at preventing the two half-shafts 3, 4 that drive the wheels from rotating at different speeds (at locking up the differential).
[0075] Returning to
[0076] The coupling device 20 is, for example, a claw coupling device. Thus, of the first and second coupling parts 25, 26, one comprises teeth while the other comprises corresponding slots into which said teeth engage when the first coupling part 25 is in the coupled position. In the embodiment depicted, the second coupling part 26 is formed of one piece with the supporting ring 19. In other words, teeth or slots are formed in the lateral face of the supporting ring 19 which face faces toward the first coupling part 25. However, although the invention has been described in connection with a claw-type coupling device, it is not restricted thereto, and the coupling device could be of another type and notably a friction coupling device.
[0077] The first coupling part 25 comprises an interior portion, not visible in
[0078] Moreover, the coupling device comprises an actuator 27 allowing the first coupling part 25 to be moved between the coupled position and the uncoupled position.
[0079] The actuator 27 comprises a frame 28 which is mounted so that it is fixed axially and circumferentially about the axis X, on a casing of the transmission system. The frame 28 is of annular shape. The frame 28 has an internal skirt 29, a radially oriented end wall 30, and an external skirt 31 and these together define an annular space. The internal skirt 29 is fitted around a lateral sleeve 32 of the part 17 of the differential case 15, while still allowing the lateral sleeve 32 and, therefore, the differential case 15, to rotate with respect to the frame 28 of the actuator 27, about the axis X.
[0080] The actuator 27 is an electromagnetic actuator. It comprises an electromagnet 33 which is housed in the frame 28. The electromagnet 33 defines, in the annular space of the frame 28, an internal housing inside which a piston 34 is guided axially in translation between a retracted position and a deployed position. The actuator 27 further comprises a cap 35, preferably a magnetic cap, which closes the internal housing. The cap 35 comprises an abutment surface which is intended to collaborate with an abutment surface of the piston 34 in order to define the deployed position of the piston 34.
[0081] The piston 34 comprises a body, of annular shape, made of ferromagnetic material such as iron or steel for example. Advantageously, as detailed hereinbelow, the piston 34 is blocked against rotation with respect to the frame 28 of the actuator 27.
[0082] The piston 34 also comprises a connecting ring 36, likewise of annular shape, by means of which the actuating force is transmitted from the body of the piston 34 to the first coupling part 25. The body of the piston 34 and the connecting ring 36 are fixed to one another by any means, such as adhesive bonding, laser welding, force-fitting, fixing pins or other means. The connecting ring 36 is advantageously made from a non-magnetic material, such as copper for example, in order to avoid undesirable emanations of magnetic flux towards the other components of the coupling device 20.
[0083] The connecting ring 36 is fixed to the first coupling part 25 by a pivot connection. In other words, the connecting ring 36 is fixed axially to the first coupling part 25 while at the same time allowing relative rotation of the first coupling part 25 with respect to the connecting ring 36 about the axis X. The axial movement of the piston 34 from the retracted position into the deployed position therefore causes the first coupling part 25 to move from the coupled position towards the uncoupled position, whereas the return of the piston 34 to the retracted position causes the first coupling part 25 to return towards the uncoupled position.
[0084] In the embodiment depicted, the connecting ring 36 has a groove 37 which is formed radially facing a groove 38 formed in the first coupling part 25. A retaining ring 39, positioned inside the two aforementioned grooves 37, 38, thus makes it possible to block axial translation of the first coupling part 25 with respect to the connecting ring 36, while at the same time allowing relative rotation. The retaining ring 39 may be mounted in the grooves 37, 38 by clip-fastening or snap-fastening.
[0085] In an alternative embodiment which has not been depicted, the groove 37 is formed directly on the body of the piston 34 and the actuator 27 therefore has no connecting ring 36.
[0086] The actuator 27 also comprises return members, not depicted, which are able to elastically return the first coupling part 25 towards the uncoupled position. The return members are, for example, helical springs which, on the one hand, bear axially against the differential case 15 and, on the other hand, bear axially against the first coupling part 25.
[0087] When the electromagnet 33 is powered with a current stronger than a threshold current, it allows the piston 34 to be moved from the retracted position to the deployed position. When the piston 34 is in the deployed position, the magnetic cap 35 exerts an attraction on the body of the piston 34, enabling it to be held in the deployed position. The strength of the current with which the electromagnet 33 is powered can then be reduced so long as it remains above the threshold current strength. When the electromagnet 33 is unpowered, or is powered with a current of a strength lower than the threshold current strength, the return members are able to overcome the force of attraction between the cap 35 and the body of the piston 34, enabling the piston 34 to be returned from the deployed position to the retracted position.
[0088] As illustrated for example in
[0089] Furthermore, advantageously, the first gearwheel 12 is contained within the axial bulk of the coupling device 20 (particularly the actuator 27, particularly the electromagnet 33, thereof). Thus, the first gearwheel 12 is positioned axially between a first radial plane, orthogonal to the axis X, passing through the end wall 30 of the frame 28, and the second gearwheel 13.
[0090] Moreover, the coupling device 20 is also equipped with a target 40 which is fixed to the piston 34 and which is positioned axially facing a sensor 41. The sensor 41 is configured to deliver a signal representative of the distance between the target 40 and the sensor 41. The signal delivered by the sensor 41 makes it possible to determine the status of the coupling device, namely whether it is in the coupled position, in the uncoupled position, or in an intermediate position. The sensor 41 is a contactless and advantageously magnetic sensor, such as a Hall-effect sensor for example. Other types of sensor, notably contactless sensors, may be used.
[0091] The target 40 comprises a detection portion 43 positioned facing the sensor 41 and a fixing tab 42 that passes through an opening in the frame 28 and which is fixed to the piston 34.
[0092] In the embodiment depicted, the target 40 is formed as one piece in magnetic sheet metal. In another embodiment which has not been depicted, the detection portion 43 is formed of a component, such as a magnetic metal sheet or magnet, which is attached to the fixing tab 42. In that case, the fixing tab 42 may be produced in a non-magnetic material.
[0093] In the embodiment depicted, the fixing tab 42 passes through an opening formed in the cap 35 of the frame 28. However, as an alternative, the fixing tab 42 may equally pass through an opening formed in the external skirt 31 of the frame 28. The fixing tab 42 may notably be fixed to the piston 34 by welding, bonding or insetting.
[0094] The passing of the fixing tab 42 of the target 40 through an opening in the frame 28 allows the creation of an antirotation member preventing or limiting relative rotation, about the axis X, of the piston 34 with respect to the frame 28.
[0095] It will be noted that, because the first coupling part 25 is axially fixed with respect to the piston 34, the axial movement of the piston 34 is equal to the axial movement of the first coupling part 25 which means that the target 40 can both be fixed to the piston 34 and deliver a signal representative of the position of the first coupling part 25. Furthermore, because the target 40 is fixed to the piston 34, which is itself unable to rotate, the target 40 is unable to rotate with respect to the sensor 41. The target 40 therefore need not be circular. This then makes it possible to limit the radial bulk of the coupling device 20 (notably of the actuator 27) and thus makes it easier to position the coupling device 20 and the first gearwheel 12 of the output shaft 7 radially one above the other.
[0096] It may further be noted that, when considered in projection along the axis X in a plane orthogonal to said axis X, the target 40 is inscribed inside an angular sector of centre X, denoted a in
[0097] In the embodiment depicted, the target 40 and the first gearwheel 12 are circumferentially opposed, one on each side of the axis X. In other words, there is a plane containing the axis X and passing both through the target 40 and through the first gearwheel 12.
[0098]
[0099] This transmission system differs from the one described hereinabove in connection with
[0100] In the embodiment depicted, the recess 44 forms a circular cavity of which the radius of curvature is substantially equal to the external radius of the first gearwheel 12.
[0101]
[0102] In
[0103] The differential function 60, performed by the two planet pinions (one of them referenced 21 and the other not depicted) and the two sun gears 23, 24, is housed inside the supporting ring 19. It may thus be seen that the coupling and uncoupling zone is positioned kinematically upstream of the differential function.
[0104] Although the invention has been described in connection with a plurality of particular embodiments, it is obvious that it is in no way limited thereto and that it comprises all technical equivalents of the means described and combinations thereof where these fall within the scope of the invention as defined in the claims.
[0105] The use of the verbs “have”, “comprise” or “include” and conjugated forms thereof does not exclude the presence of elements or steps other than those stated in a claim.
[0106] In the claims, any reference sign between parentheses should not be interpreted as limiting the claim.