Gearbox for mobility device
The gearbox design addresses the issue of vibration transmission by incorporating a stiffness element that redirects axial efforts and absorbs vibrations, resulting in reduced deformations and improved stability for mobility device gearboxes.
Patent Information
- Application Number
- FR2022014431
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2022-12-23
- Publication Date
- 2025-03-28
- Estimated Expiration
- 2042-12-23
AI Technical Summary
Existing gearboxes for mobility devices, particularly those with electric motors, face issues with vibration transmission from the intermediate shaft to the cover and subsequently to the case, leading to undesirable deformations and vibrations on the engine side.
The gearbox design incorporates a stiffness element connected to the second bearing and the case, which guides the axial efforts of the intermediate shaft away from direct transmission to the cover. This stiffness element, often a threaded rod, is positioned to absorb vibrations and differential dilations, ensuring secure fixation and minimizing unwanted vibrations.
The introduction of the stiffness element effectively reduces the transmission of vibrations from the intermediate shaft to the cover and case, thereby minimizing deformations and vibrations on the engine side, enhancing the overall stability and performance of the gearbox.
Smart Images
Figure 00000008_0000 
Figure 00000008_0001 
Figure 00000009_0000
Abstract
Description
Title of the invention: Gearbox for mobility device
[0001] The present invention relates to a gearbox for a mobility device. In one example, the invention relates to a speed reducer for a vehicle comprising an electric motor. The invention also relates to a transmission assembly comprising such a gearbox associated with an electric motor.
[0002] Speed reducers are known comprising a housing and a cover. The housing is intended to enclose an electric motor on a first side. The housing is intended on a second side to be associated with the cover to form a housing in which an input shaft of the electric motor and an intermediate shaft extend. The intermediate shaft is supported at a first end by the housing via a first bearing. The intermediate shaft is supported at a second end by the cover via a second bearing. The housing and the cover are connected to each other by first fixing means generally arranged around the entire periphery of the housing and the cover.
[0003] In order to improve the attachment of the cover to the housing, it is known to attach the cover to the housing by inserting a threaded rod through the cover and through a passage hole in the intermediate shaft until the rod is screwed into the housing. The rod is positioned in such a way that it is mounted to bear against the cover while being screwed into the housing. Thus, in addition to the first attachment means, a second attachment means can be used to reinforce the attachment of the cover to the housing, in particular in areas of the cover likely to be subject to vibrations.
[0004] However, it has been found that vibrations of the intermediate shaft are transmitted to the cover, by the intermediate shaft pressing against the cover. In addition, these same vibrations can therefore be transmitted via the threaded rod to the housing. Undesirable deformations and vibrations can then occur, among other things, on the engine side.
[0005] The invention aims to solve the above-mentioned problems.
[0006] To this end, the invention relates to a gearbox of a mobility device, said gearbox comprising
[0007] - an input shaft and an intermediate shaft, the input shaft and the intermediate shaft cooperating with each other by meshing with each other,
[0008] - a cover and a housing, the cover and the housing being connected to each other such as to form a housing enclosing and supporting the input shaft and the intermediate shaft,
[0009] - the intermediate shaft being supported by the housing and by the cover by by means of a first bearing and a second bearing respectively,
[0010] - the cover having a first orifice arranged opposite a second orifice of the intermediate shaft, and
[0011] - a stiffener connecting the second bearing to the housing by inserting the stiffener into the through the first hole and the second hole, the stiffener being guided radially and axially in the first hole of the cover.
[0012] Thus, the axial forces of the intermediate shaft are no longer transmitted directly to the cover but to the stiffener. In addition, thus housed in the first orifice of the cover, the stiffener is capable of sliding axially inside the first orifice to adapt to potential vibrations and / or differential expansions.
[0013] In particular in one embodiment, the stiffener is guided radially and axially in the first orifice of the cover while being positioned in abutment against the second bearing.
[0014] In one embodiment, the stiffener is formed by a threaded rod.
[0015] In one embodiment, the stiffener has a head forming a plug, the head being slidably mounted in the first orifice of the cover by complementarity of shape.
[0016] In one embodiment, the cap is fluid-tight.
[0017] In one embodiment, the head has a groove in which is housed a sealing gasket capable of being compressed between the groove and an edge of the first hole in the cover.
[0018] In one embodiment, the second bearing is formed by an outer ring mounted on the cover, by an inner ring mounted on the intermediate shaft and by balls arranged between the outer ring and the inner ring, the stiffener being positioned in axial abutment against the outer ring of the second bearing.
[0019] In one embodiment, the stiffener is of the same material as that of the intermediate shaft.
[0020] In one embodiment, the stiffener is of the same material as that of the housing.
[0021] In one embodiment, it comprises a sheet metal interposed between the housing and the stiffener, on the one hand, and between the housing and the first bearing, on the other hand. A differential expansion which would overload the first and / or the second bearing can thus be at least reduced. In one example, the sheet metal is made of steel allowing the entire loop of forces to pass through steel. In one example, the sheet metal is stamped.
[0022] In one embodiment, a wall of the intermediate shaft delimiting the second orifice has a first groove extending helically along the wall. This shape results in an example of machining carried out along the wall delimiting the second orifice.
[0023] Or in another embodiment, an outer surface of the stiffener has a second groove that extends helically along this outer surface. This second groove may also result from machining. Such helical machining advantageously allows a fluid to be moved by differential rotation between the stiffener and the intermediate shaft. This also allows the first and / or second bearing to be lubricated.
[0024] The invention also relates to a transmission assembly comprising a gearbox as previously described and an electric motor, in which the housing contains the electric motor, the input shaft being rotatably connected to a rotor shaft of the electric motor.
[0025] The invention will be better understood upon reading the following description and examining the accompanying figures. These figures are given only for illustrative purposes but in no way limit the invention.
[0026] [Fig.l] or [Fig.l] illustrates a schematic representation of a transmission assembly according to a first embodiment of the invention;
[0027] [Fig.2] or [Fig.2] illustrates a schematic representation of a gearbox according to a second embodiment of the invention;
[0028] [Fig.3] or [Fig.3] illustrates a schematic representation of a gearbox according to a third embodiment of the invention, and
[0029] [Fig.4] or [Fig.4] illustrates a schematic representation of a gearbox according to a fourth embodiment of the invention.
[0030] Identical, similar or analogous elements retain the same reference from one figure to another.
[0031] [Fig. 1] shows a transmission assembly 28 of a mobility device. In this example, the transmission assembly 28 comprises a gearbox 1 and an electric motor 2. In this particular example, the gearbox is a speed reducer 1 of a motor vehicle (not shown). This speed reducer 1 is associated with the electric motor 2. The speed reducer 1 has an input shaft 3 which is rotatably connected to a rotor shaft 27 of the electric motor 2. The input shaft 3 extends longitudinally along an axis of rotation X. The speed reducer 1 also has an intermediate shaft 4. The intermediate shaft 4 extends longitudinally along an axis of rotation X' and parallel to the axis of rotation X of the input shaft 3. The input shaft 3 has a first meshing section 5.The intermediate shaft 4 meshes with the input shaft 3 via a gear wheel 6 positioned fixed in rotation on the intermediate shaft 4 and which cooperates with the first meshing section 5.
[0032] The speed reducer 1 has a cover 7 and a housing 8 connected to each other in such a way as to form a housing 9 enclosing and supporting the input shaft 2 and the intermediate shaft 3. The intermediate shaft 3 is supported by the housing 8 and by the cover 7 by means of a first bearing 10 and a second bearing 11 respectively. In particular, the first bearing 10 is positioned between the housing 8 and one end of the intermediate shaft 4 and the second bearing 11 is positioned between the cover 7 and an opposite end of the intermediate shaft 4.
[0033] The cover 7 has a first orifice 12 and the intermediate shaft 4 is crossed by a second orifice 13. The cover 7 and the intermediate shaft 4 are positioned relative to each other in such a way that the first orifice 12 is located coaxially opposite the second orifice 13.
[0034] The speed reducer 1 comprises a stiffener 14 which is formed by a threaded rod 15 which has a head 16 forming a plug. The head 16 is slidably mounted in the first orifice 12 of the cover 7 by complementary shape. The plug is fluid-tight. To do this, and in this example, the head 16 has a groove 17 in which is housed a seal 18 capable of being compressed between the groove 17 and an edge 18 of the first orifice 12 of the cover 7. The stiffener 14 extends through the first orifice 12 and the second orifice 13 while being guided radially and axially in the first orifice 12 of the cover 7.
[0035] The second bearing 11 is connected to the housing 8 by inserting the stiffener 14 into the first orifice 12 and into the second orifice 13.
[0036] The second bearing 11 is formed by an outer ring 19 mounted fixed in rotation on the cover 7, by an inner ring 20 mounted fixed in rotation on the intermediate shaft 4 and by balls 21 arranged between the outer ring 19 and the inner ring 20. The stiffener 14 is positioned in axial support against the outer ring 19 of the second bearing 11.
[0037] The stiffener 14 is made of the same material as that of the intermediate shaft 4.
[0038] The stiffener 14 is made of the same material as that of the housing 8.
[0039] [Fig. 2] illustrates a second embodiment of the invention which differs from the previous one in that a stamped sheet 22 is interposed between the housing 8 and the stiffener 14, on the one hand, and between the housing 8 and the first bearing 10, on the other hand.
[0040] [Fig. 3] illustrates a third embodiment of the invention which differs from that of [Fig. 1] in that a wall 24 delimiting the second orifice 13 of the intermediate shaft 4 has a first groove 23 which extends helically along the wall 24.
[0041] [Fig. 4] illustrates a fourth embodiment of the invention which differs from that of [Fig. 1] in that the stiffener 14 has along an external surface 25 a second groove 26 which also extends helically along the outer surface 25.
[0042] Such helical machining advantageously allows a displacement of a fluid (represented by an arrow in [Fig.3]) by differential rotation between the stiffener 14 and the intermediate shaft 4. This also advantageously allows the first bearing 10 and / or the second bearing 11 to be greased.
[0043] Of course, the preceding description has been given by way of example only and does not limit the scope of the invention, which would not be exceeded by replacing the various elements with any other equivalents.
[0044] Furthermore, the various features, variations, and / or embodiments of the present invention may be combined with each other in various combinations, provided that they are not incompatible or mutually exclusive.
Claims
Claims
1. Gearbox (1) of a mobility device, said gearbox comprising - an input shaft (3) and an intermediate shaft (4), the input shaft and the intermediate shaft cooperating with each other by meshing with each other, - a cover (7) and a housing (8), the cover and the housing being connected to each other in such a way as to form a housing (9) enclosing and supporting the input shaft and the intermediate shaft, - the intermediate shaft being supported by the housing and by the cover by means of a first bearing (10) and a second bearing (11) respectively, - the cover having a first orifice (12) arranged opposite a second orifice (13) of the intermediate shaft, and - a stiffener (14) connecting the second bearing to the housing by inserting the stiffener through the first orifice and the second orifice, the stiffener being guided radially and axially in the first hole in the cover,in which the gearbox comprises a sheet metal (22) interposed between the housing and the stiffener, on the one hand, and between the housing and the first bearing, on the other hand.,
2. Gearbox according to claim 1, wherein the stiffener is formed by a threaded rod (15).
3. Gearbox according to claim 1 or 2, in which the stiffener has a head (16) forming a plug, the head being slidably mounted in the first orifice of the cover by form complementarity.
4. A gearbox according to claim 3, wherein the cap is fluid tight.
5. A gearbox according to claim 3 or claim 4, wherein the head has a groove (17) in which is housed a seal (18) capable of being compressed between the groove and an edge of the first orifice of the cover.
6. Gearbox according to one of claims 1 to 5, in which the second bearing is formed by an outer ring (19) mounted on the cover, by an inner ring (20) mounted on the intermediate shaft and by balls (21) arranged between the outer ring
7.
8.
9.
10.
11. and the inner ring, the stiffener being positioned axially against the outer ring of the second bearing. Gearbox according to one of claims 1 to 6, wherein the stiffener is of the same material as that of the intermediate shaft. Gearbox according to one of claims 1 to 7, wherein the stiffener is of the same material as that of the housing. Gearbox according to one of claims 1 to 8, in which a wall (24) of the intermediate shaft delimiting the second orifice has a first groove (23) extending helically along the wall. Gearbox according to one of claims 1 to 8, wherein an outer surface (25) of the stiffener has a second groove (26) which extends helically along this outer surface. Transmission assembly (28) of a mobility device comprising a gearbox (1) according to one of claims 1 to 10 and an electric motor (2), in which the housing encloses the electric motor, the input shaft being rotatably connected to a rotor shaft (27) of the electric motor.