Torque transmission assembly for a mobility apparatus

Abstract

The invention relates to a transmission assembly (100) for a mobility apparatus, said assembly comprising an electric motor comprising a rotor shaft (103), a speed reduction device (104) comprising at least one transmission shaft (106) for cooperating directly or indirectly with the rotor shaft to transmit a motor torque, and a vibration damping device (105) for reducing vibrations, the rotor shaft or the transmission shaft forming a hollow shaft defining a cavity (111), the damping device being inserted into the cavity.

Description

[0001] TORQUE TRANSMISSION ASSEMBLY FOR A MOBILITY DEVICE

[0002] The invention relates to a torque transmission assembly for a mobility device, such as a motor vehicle, equipped with an electric motor.

[0003] The invention relates to a transmission assembly which comprises a speed reduction device receiving a torque supplied by a rotor of an electric motor. Document DE10017396 describes a transmission assembly comprising an electric motor equipped with a stator and a rotor. The electric motor is rotatably connected to a transmission shaft via the rotor. To reduce the impact of rotor vibrations on the transmission assembly, an elastic element is interposed between the rotor and the gearbox input shaft. However, the presence of this elastic element is not entirely satisfactory and does not prevent the electric motor from being moved, causing the transmission assembly to bend.

[0004] The invention aims to provide a transmission assembly for a mobility device which solves the above-mentioned problems.

[0005] To this end, the invention relates to a transmission assembly for a mobility device, said assembly comprising an electric motor comprising a rotor shaft, a speed reduction device comprising at least one transmission shaft capable of cooperating directly or indirectly with the rotor shaft to transmit a motor torque, a vibration damping device capable of reducing vibrations, the rotor shaft or the transmission shaft forms a hollow shaft defining a housing, the damping device being inserted into the housing.

[0006] According to one embodiment of the invention, the damping device is tuned to a rotation frequency which is 20 to 30 times the rotation frequency of the rotor shaft.

[0007] The stiffness of the spring element is calculated so that the mass does not touch the wall of the housing.

[0008] According to one embodiment, the damping device comprises a mass and a spring element, the spring element being positioned at one end fixed in rotation to the rotor shaft or to the transmission shaft and cooperating at another end with the mass. Thus the damping device advantageously forms an inertial beater. The mass is designed in such a way that it does not touch an internal wall delimiting the housing, even in operation. According to one embodiment, the spring element forms a rod extending along an elongation axis (X) of the rotor shaft or of the transmission shaft, the rod comprising a first end capable of being mounted fixed on the rotor shaft or on the transmission shaft and a second end capable of being connected to the mass. The rod can be made of an elastic material of a predefined stiffness.

[0009] According to one embodiment, the spring element is arranged around the rotor shaft or the transmission shaft, between the rotor shaft or the transmission shaft and the mass.

[0010] According to one embodiment, the spring element forms a corrugated ring which is arranged in an annular groove formed by an inner wall of the housing. In particular, the spring element forms a corrugated ring which is arranged circumferentially with respect to the transmission shaft or the rotor shaft. The annular groove is made in such a way that the corrugated ring partially protrudes from this same groove.

[0011] In another example, several undulating rings could be provided distributed along the wall delimiting the housing. To do this, as many ring grooves could be provided.

[0012] According to one embodiment, the spring element forms at least one corrugated lamella arranged between the rotor shaft or the transmission shaft and the mass.

[0013] According to one embodiment, the spring element forms a wavy strip.

[0014] According to one embodiment, this corrugated lamella forms a tube whose wall is formed of longitudinal corrugations.

[0015] According to one embodiment, portions of longitudinal corrugations of the corrugated lamella are each arranged in a corresponding longitudinal groove formed by an internal wall of the housing. The longitudinal groove is made in such a way that the portion of longitudinal corrugations partially protrudes from this same groove.

[0016] According to one embodiment, the corrugated lamella is arranged longitudinally relative to the rotor shaft or the transmission shaft.

[0017] According to one embodiment, the housing is closed by means of a sealing means.

[0018] According to one embodiment, the housing is sealed. An adhesive or an elastomeric element may be interposed between the rotor shaft or the transmission shaft and the sealing means.

[0019] According to one embodiment, the sealing means is a plug mounted on the rotor shaft or on the transmission shaft by fitting, or by screwing or by gluing on the rotor shaft or on the transmission shaft. According to one embodiment, the mass is configured in such a way that it can define two resonance modes, a first resonance mode resulting from a radial displacement of the mass and a second resonance mode resulting from a tilting of the mass around its center of gravity. In one example, the mass forms a parallelepiped structure with a square or rectangular longitudinal section.

[0020] By convention, the "radial" orientation is directed orthogonally to the axial orientation. The axial orientation refers, depending on the context, to the axis of rotation of the rotor shaft and / or the axis of rotation of the drive shaft. The "circumferential" orientation is directed orthogonally to the axial direction and orthogonally to the radial direction.

[0021] The invention will be better understood by reading the following description and examining the accompanying figures. These figures are given only for illustrative purposes but in no way limit the invention.

[0022] Figure 1 or [Figure 1] is a schematic representation of a transmission assembly, according to a first example of the invention;

[0023] Figure 2A or [Figure 2A] is a schematic representation of a transmission assembly, according to a second example of the invention;

[0024] Figure 2B or [Figure 2B] is a schematic representation of a spring element, according to the second example of the invention, and

[0025] Figure 3 or [Figure 3] is a schematic representation of a transmission assembly, according to a third example of the invention.

[0026] Figure 1 illustrates a transmission assembly 100 for a motor vehicle of the hybrid or electric type. The transmission assembly 100 comprises an electric motor 102 comprising a rotor shaft 103, a speed reduction device 104, a vibration damping device 105 capable of reducing vibrations. The speed reduction device 104 comprises a first transmission shaft 106 which cooperates directly with the rotor shaft 103 to transmit a motor torque. The speed reduction device 104 also comprises a second transmission shaft 107 which cooperates with the first transmission shaft 106. To do this, the first transmission shaft 106 and the second transmission shaft 107 respectively comprise a toothing 108 and 109 adapted to cooperate with each other and allow rotational coupling of the first transmission shaft 106 with the second transmission shaft 107.

[0027] The transmission shaft 106 has an end 110 intended to cooperate with the rotor shaft 103. At this end 110 a housing 111 is formed. This housing 111 is hollowed out longitudinally relative to an axis of rotation or axis X of elongation of the first transmission shaft 106. This axis X of elongation is coaxial with another axis of rotation of the rotor shaft or axis X' of elongation of the rotor shaft 103. The housing 111 is delimited by a wall 112 of the first transmission shaft 106. According to the invention, the vibration damping device 105 is inserted into the housing 111.

[0028] In particular according to this first example, the damping device 105 comprises a mass 113 and a rod 114. The rod 114 extends along the elongation axis X of the first transmission shaft 106. The rod 114 comprises a first end 115 and a second end 116. The rod 114 is mounted fixed on the first transmission shaft 106 by its first end 115. The mass 113 is fixed to the rod 114 by the second end 116. The rod 114 has an elastic material allowing the mass 113 to be able to tilt radially relative to the elongation axis X under the effect of vibrations.

[0029] The housing 111 is closed by a closure means 117. This closure means may be an insert 117 which is mounted fixed by screwing onto the end 110 of the first transmission shaft 106 by means of screws such as 118.

[0030] A sealing means (not shown) may be added between the sealing means and the first drive shaft 106 to prevent dust or fluid from entering the housing 111.

[0031] Other sealing means may be provided, such as a plug (not shown) force-fitted into the first transmission shaft 106.

[0032] Figures 2A and 2B illustrate a second exemplary embodiment of the invention. In this example, a transmission assembly 200 is partially illustrated which comprises a transmission shaft 206, a housing 211 delimited by a wall 212, a vibration damping device 205 arranged in the housing 211 (Figure 2A). The damping device 205 comprises a mass 213 and a spring element 214. The mass 213 forms a parallelepiped structure of square longitudinal section. The spring element 214 is formed by at least one corrugated ring 214 (Figure 2B). This corrugated ring 214 is arranged circumferentially around the transmission shaft 206 along the wall 212 of the housing 211. To hold the corrugated ring 214 axially in position inside the housing 211, an annular groove 219 may advantageously be provided in a thickness of the wall 212.The mass 213 is placed in the housing 211 while being held in position by an elastic support against the corrugated ring 214. The mass 213 is positioned inside the housing 211 in such a way that it does not touch the wall 212. The housing 211 is closed by an insert 217 by means, for example, of screws such as 218.

[0033] In Figure 3 is illustrated a third exemplary embodiment of the invention. In this example is partially illustrated a transmission assembly 300 which comprises a vibration damping device 305. This damping device 305 comprises a corrugated strip 314 and a mass 313. This corrugated strip 314 forms a tube whose wall is formed of longitudinal corrugations. This corrugated strip 314 is arranged longitudinally along a wall 312 of the housing 311. To maintain the corrugated strip 314 axially in position inside the housing 311, it may advantageously be provided to position a circlip (not shown) at the entrance to the housing 311. To maintain the corrugated strip 314 circumferentially in position inside the housing 311, longitudinal grooves 319 may be provided.Thus, the corrugated lamella 314 is inserted through the housing 311 such that corrugated portions (not shown) of the corrugated lamella 314 are inserted into these same grooves. The mass 313 is placed in the housing 311 while being held in position by elastic radial support against the corrugated lamella 314.

[0034] Mass 313 forms a parallelepiped structure with a rectangular longitudinal section.

[0035] The housing 311 is closed by an insert 317 similar to the other two inserts 117 and 217 by means of screws such as 318.

[0036] The mass 313 is positioned inside the housing 311 in such a way that it does not touch the wall 312 or the insert 317.

Claims

Claims

1. Transmission assembly (100,200,300) for a mobility device, said assembly comprising an electric motor comprising a rotor shaft (103), a speed reduction device (104,204,304) comprising at least one transmission shaft (106,206,306) capable of cooperating directly or indirectly with the rotor shaft to transmit a motor torque, a vibration damping device (105,205,305) capable of reducing vibrations, the rotor shaft or the transmission shaft forms a hollow shaft defining a housing (111,211,311), the damping device being inserted into the housing.

2. A transmission assembly according to claim 1, wherein the damping device comprises a mass (113,213,313) and a spring element (114,214,314), the spring element being positioned at one end rotationally fixed to the rotor shaft or the transmission shaft and cooperating at another end with the mass.

3. A transmission assembly according to claim 2, wherein the spring element forms a rod (114) extending along an elongation axis (X) of the rotor shaft or the transmission shaft, the rod comprising a first end (115) capable of being mounted fixedly on the rotor shaft or on the transmission shaft and a second end (116) capable of being connected to ground.

4. A transmission assembly according to claim 2, wherein the spring element is disposed around the rotor shaft or the transmission shaft, between the rotor shaft or the transmission shaft and the mass.

5. A transmission assembly according to claim 4, wherein the spring element forms a corrugated ring which is disposed in an annular groove (219) formed by an inner wall (212) of the housing.

6. Transmission assembly according to claim 4, in which the spring element forms a corrugated lamella, this corrugated lamella forming a tube whose wall is formed of longitudinal corrugations.

7. A transmission assembly according to claim 6, wherein portions of longitudinal corrugations of the corrugated strip are each arranged in a corresponding longitudinal groove (319) formed by an inner wall (312) of the housing.

8. Transmission assembly according to one of claims 1 to 7, wherein the housing is closed by means of a sealing means (117,217,317).

9. Transmission assembly according to one of claims 1 to 8, in which the housing is sealed.

10. A transmission assembly according to claim 8 or claim 9, wherein the sealing means is a plug mounted on the rotor shaft or on the transmission shaft by fitting, or by screwing or by gluing onto the rotor shaft or on the transmission shaft.

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