Bridge

Abstract

An electric bridge is provided, which includes an electric motor, a planetary gear set, an input shaft, a driving gear and a differential, wherein the output shaft of the electric motor is torsionally connected to the input shaft, and the planetary gear set includes: a sun gear torsionally mounted to the input shaft; a planet carrier rotatably supported on the input shaft relative to the input shaft; a first planetary gear and a second planetary gear mounted to the planet carrier, the first planetary gear and the second planetary gear are torsionally connected, the second planetary gear meshes with the sun gear, and the diameter of the second planetary gear is greater than the diameter of the first planetary gear; and a ring gear meshed with the first planetary gear, wherein the driving gear is torsionally mounted to the planet carrier, and the driving gear transmits the rotation of the planet carrier to the differential. In the present invention, in the case of a housing of the same size (diameter) (i.e., a ring gear of the same diameter), a sun gear of a smaller diameter can be used, thereby improving the transmission ratio.

Description

Technical Field

[0001] The present invention relates to the field of vehicle accessories, and in particular to an electric bridge which can be applied to, for example, pure electric vehicles and hybrid electric vehicles. Background Art

[0002] Figure 1 A known electric bridge having an offset structure (ie, the shaft of the motor and the shaft of the differential are not coaxial but are radially offset) is schematically shown.

[0003] The electric bridge 100 includes an electric motor 1 , a planetary gear set 2 , a differential 3 , a housing 4 , an input shaft 5 and a driving gear 6 .

[0004] An output shaft 11 of the motor 1 is supported by two bearings 12 and 13 on a housing 14 of the motor.

[0005] The planetary gear set 2 includes a planet carrier 21, a sun gear 24, a planet gear 26 and a ring gear 27. The planet carrier 21 is supported on the housing 4 of the electric bridge 100 through two ball bearings 22 and 23. The sun gear 24 is integrated into the input shaft 5, and one end of the input shaft 5 in the axial direction ( Figure 1 The left end portion in the middle) is connected to the output shaft 11 through a spline, and the other end portion in the axial direction of the input shaft 5 ( Figure 1 The right end in FIG. 2 is supported on the planetary carrier 21 by a ball bearing 25. The planetary gear 26 is mounted on the planetary carrier 21 by a pin and a needle bearing. The ring gear 27 is fixed to the housing 4.

[0006] The driving gear (pinion) 6 is welded to the planet carrier 21 .

[0007] The differential 3 also has a planetary gear set. The driven gear (large gear) 31 of the differential 3 is integrated into the planet carrier 32. The driven gear 31 meshes with the driving gear 6. The planet carrier 32 is supported on the housing 4 through two bearings 33 and 34. The long planetary gears 35 and the short planetary gears 38 that mesh with each other are mounted on the planet carrier 32 through pins and needle bearings. The sun gear 36 meshes with the short planetary gears 38, and the sun gear 37 meshes with the long planetary gears 35. The two sun gears 36 and 37 are connected to the two half shafts 7 and 8 respectively.

[0008] In the above-mentioned electric bridge 100, the power output (torque) from the motor 1 is transmitted to the sun gear 24 via the output shaft 11 and the input shaft 5, and then transmitted to the planetary carrier 21 via the planetary gear 26, and then transmitted from the planetary carrier 21 to the driving gear 6, and then transmitted to the driven gear 31 (differential 3).

[0009] In the above-mentioned electric bridge 100, the structure of the planet carrier, especially the planet carrier 21, is relatively complex, the supporting structure of each component is relatively complex, and a large number of bearings are used, which leads to greater manufacturing difficulty and higher cost.

[0010] More specifically, the planet carrier 21 includes: a first small diameter portion 21A, which constitutes one end of the planet carrier 21 in the axial direction and is supported by the housing 4 via a ball bearing 22; a second small diameter portion 21B, which constitutes the other end of the planet carrier 21 in the axial direction and is supported by the housing 4 via a ball bearing 23; and a large diameter portion 21C, which is located between the first small diameter portion 21A and the second small diameter portion 21B, and the planetary gear 26 is installed in the large diameter portion 21C. The structure of the planet carrier 21 is complex. The input shaft 5 is supported by the second small diameter portion 21B of the planet carrier 21 through the ball bearing 25, and the size of the planet carrier 21 is relatively large. The planet carrier 21 is supported by two ball bearings 22 and 23 on the housing 4, and the sizes of the two ball bearings 22 and 23 are generally large due to the large size of the planet carrier 21. More and larger bearings mean higher costs. The size of the driving gear 6 is relatively large due to the size of the planet carrier 21, and the size of the driving gear 6 affects the transmission ratio of the electric bridge 100.

[0011] The planetary gear differential 3 has many components and a complex structure, which means a higher cost.

[0012] Without an intermediate shaft, it is difficult to obtain a large transmission ratio (speed ratio) in a compact structure. Summary of the invention

[0013] The present invention is made in view of the above-mentioned state of the prior art. One object of the present invention is to provide an electric bridge which can obtain a larger transmission ratio based on a smaller radial size.

[0014] An electric bridge is provided, which includes an electric motor, a planetary gear set, an input shaft, a driving gear and a differential, wherein the output shaft of the electric motor is torsionally connected to the input shaft, and the planetary gear set includes:

[0015] a sun gear mounted torsionally fixed to the input shaft;

[0016] a planet carrier rotatably supported on the input shaft relative to the input shaft;

[0017] a first planetary gear and a second planetary gear mounted to the planet carrier, the first planetary gear and the second planetary gear being torsionally connected, the second planetary gear being meshed with the sun gear, the second planetary gear having a diameter greater than that of the first planetary gear; and

[0018] a ring gear meshing with the first planetary gears;

[0019] The driving gear is mounted to the planet carrier in a torsion-proof manner, and the driving gear transmits the rotation of the planet carrier to the differential.

[0020] In at least one embodiment, the output shaft of the electric motor shares a common shaft with the input shaft.

[0021] In at least one embodiment, the common shaft is supported by the housing of the electric bridge via two bearings located at both axial ends of the common shaft and a bearing located at an axial middle position of the common shaft.

[0022] In at least one embodiment, the planet carrier is supported on the input shaft via needle bearings.

[0023] In at least one embodiment, the planetary carrier includes a large diameter portion located on one axial end side and a small diameter portion located on the other axial end side, the first planetary gear and the second planetary gear are mounted on the large diameter portion, the small diameter portion is supported on the input shaft via a needle bearing, and the driving gear is mounted to the small diameter portion to prevent torsion.

[0024] In at least one embodiment, the driving gear is mounted to the small diameter portion via a spline or welded to the small diameter portion.

[0025] In at least one embodiment, the differential includes: a differential housing; a bevel gear set installed in the differential housing; and a driven gear mounted to the differential housing in a torsion-proof manner, the side shaft gears of the bevel gear set being spline-connected to the side shafts, and the driven gear being meshed with the driving gear.

[0026] In at least one embodiment, the first planetary gears and the second planetary gears are staggered in the axial direction.

[0027] In at least one embodiment, the first planetary gear and the second planetary gear are formed as one body, and the first planetary gear and the second planetary gear are mounted to the planet carrier via pins and needle bearings.

[0028] In at least one embodiment, the ring gear is fixed to a housing of the electric bridge.

[0029] In the present invention, since the first planetary gear meshes with the ring gear, the second planetary gear meshes with the sun gear, and the diameter of the second planetary gear is larger than that of the first planetary gear, a sun gear with a smaller diameter can be used in the case of a housing of the same size (diameter) (i.e., a ring gear of the same diameter), thereby improving the transmission ratio. Alternatively, the size of the components (especially the radial size of the housing of the electric bridge) can be reduced while keeping the transmission ratio unchanged. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A known bridge with a bias structure is schematically shown.

[0031] Figure 2 A bridge according to a first embodiment of the invention is schematically shown.

[0032] Figure 3 A bridge according to a second embodiment of the invention is schematically shown.

[0033] Description of Reference Numerals

[0034] 100 electric bridge; 1 electric motor; 11 output shaft of electric motor; 12, 13 bearings; 14 housing of electric motor; 2 planetary gear set; 21 planet carrier; 21A first small diameter portion; 21B second small diameter portion; 21C large diameter portion; 22, 23, 25 ball bearings; 24 sun gear; 26 planetary gear; 27 ring gear; 3 differential; 31 driven gear; 32 planet carrier; 33, 34 bearings; 35 long planetary gear; 36, 37 sun gear; 38 short planetary gear; 4 housing of electric bridge; 5 input shaft; 6 driving gear; 7, 8 half shafts;

[0035] 200, 200A electric bridge; 210 electric motor; 211 output shaft of electric motor; 212, 213 bearings; 220 planetary gear set; 221 planet carrier; 221A large diameter portion; 221B small diameter portion; 222 pin; 223 needle bearing; 224 sun gear; 225 first planetary gear; 226 second planetary gear; 227 ring gear; 230 differential; 231 driven gear; 232 differential housing; 233, 234 bearings; 235 bevel gear set; 238, 239 half shafts; 240 housing of electric bridge; 250 input shaft; 251 bearing shaft; 260 driving gear. DETAILED DESCRIPTION

[0036] The exemplary embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood that these specific descriptions are only used to teach those skilled in the art how to implement the present invention, and are not intended to exhaust all possible modes of the present invention, nor to limit the scope of the present invention.

[0037] First embodiment

[0038] like Figure 2 As shown, the first embodiment of the present invention provides an electric bridge 200 . The electric bridge 200 includes a motor 210 , a planetary gear set 220 , a differential 230 , a housing 240 , an input shaft 250 , and a driving gear 260 .

[0039] In this embodiment, the output shaft 211 and the input shaft 250 of the motor 210 share a common shaft (i.e., are the same shaft). However, it should be understood that the present invention is not limited thereto, and the output shaft 211 and the input shaft 250 may be two separately formed shafts, connected together in a torsion-resistant manner by splines or welding.

[0040] The output shaft 211 and the input shaft 250 are supported via three bearings 212, 213 and 251. The bearing 212 located at one axial end of the output shaft 211 and the input shaft 250, the bearing 213 located at the axial middle position of the output shaft 211 and the input shaft 250, and the bearing 251 located at the other axial end of the output shaft 211 and the input shaft 250 can be supported by the housing 240 of the bridge 200.

[0041] The planetary gear set 220 includes a planet carrier 221, a sun gear 224, a first planetary gear 225, a second planetary gear 226, and a ring gear 227. The planet carrier 221 is rotatably supported on the input shaft 250 by, for example, a needle bearing. The sun gear 224 is torsionally mounted to the input shaft 250 by, for example, a spline. The first planetary gear 225 and the second planetary gear 226 may be integrally formed or torsionally connected together. The first planetary gear 225 and the second planetary gear 226 may be staggered in the axial direction. The first planetary gear 225 and the second planetary gear 226 are mounted on the planet carrier 221 by a pin 222 and a needle bearing 223. Among them, the first planetary gear 225 is meshed with the ring gear 227, and the second planetary gear 226 is meshed with the sun gear 224. The diameter of the second planetary gear 226 is larger than the diameter of the first planetary gear 225. The ring gear 227 is fixed to the housing 240.

[0042] The driving gear (pinion) 260 is mounted to the planet carrier 221 by splines or welded.

[0043] In the present embodiment, the differential 230 is exemplarily but not limitingly a bevel gear differential, and may include a driven gear (differential gear) 231 , a differential housing 232 , and a bevel gear set 235 .

[0044] The driven gear 231 is welded or bolted to the differential housing 232. The differential housing 232 is supported on the housing 240 by bearings 233 and 234. The two side shaft gears in the bevel gear set 235 are respectively connected to the two half shafts 238 and 239 by splines. It should be understood that the half shafts 238 and 239 may or may not be part of the differential 230.

[0045] In the electric bridge 200 , the power (torque) transmission path is as follows.

[0046] Output shaft 211 of motor 210 →input shaft 250 →sun gear 224 →second planetary gear 226 →first planetary gear 225 →planet carrier 221 →driving gear 260 →driven gear 231 →differential case 232 →bevel gear set 235 →axishafts 238 , 239 .

[0047] In this embodiment, the offset structure of the electric bridge 200 includes a planetary gear set 220 and a cylindrical gear set (a driving gear 260 and a driven gear 231 ).

[0048] It should be understood that the housing 240 of the electric bridge 200 in this embodiment may include the housing of the motor 210, the housing of the planetary gear set 220, and possibly a common housing of the motor 210 and the planetary gear set 220. In at least one embodiment of the present invention, the transmission ratio can be increased, especially while maintaining the size (especially the radial size) of the housing of the planetary gear set 220.

[0049] It should be understood that the term “torsionally rigidly connected” or “torsionally rigidly mounted” in the present invention means that two components that are connected or mounted to each other substantially rotate together, thereby being able to transmit power / torque.

[0050] Some of the beneficial effects that can be obtained by this embodiment are described below.

[0051] (1) The output shaft 211 of the motor 210 and the input shaft 250 share one shaft, which can reduce the number of shafts.

[0052] (2) The shaft shared by the output shaft 211 and the input shaft 250 is supported by three bearings, which can improve the support rigidity.

[0053] (3) In this embodiment, the planet carrier 221 is supported on the input shaft 250 via a needle bearing, and the input shaft 250 is supported on the housing 240, such as Figure 1 Compared with the planet carrier 21 shown supported by the housing 4 and the input shaft 5 supported by the planet carrier 21, the size of the planet carrier 221 can be reduced and the structure can be simplified. At the same time, smaller bearings can be used to reduce the number of bearings.

[0054] More specifically, in Figure 1 In the structure, the planetary carrier 21 includes: a first small diameter portion 21A, which constitutes one axial end of the planetary carrier 21 and is supported on the housing 4 via a ball bearing 22; a second small diameter portion 21B, which constitutes the other axial end of the planetary carrier 21 and is supported on the housing 4 via a ball bearing 23; and a large diameter portion 21C, which is located between the first small diameter portion 21A and the second small diameter portion 21B, and the planetary gear 26 is installed on the large diameter portion 21C.

[0055] Reference Figure 2The planet carrier 221 in this embodiment includes a large diameter portion 221A located at one end side in the axial direction and a small diameter portion 221B located at the other end side in the axial direction. The first planetary gear 225 and the second planetary gear 226 are mounted on the large diameter portion 221A. The small diameter portion 221B is rotatably mounted on the input shaft 250 through a needle bearing. Figure 1 Compared with the structure of the present invention, the number of bearings can be reduced. The driving gear 260 is fixedly connected to the small diameter portion 221B.

[0056] It can be seen that the structure of the planet carrier 221 in this embodiment is more Figure 1 The planet carrier 21 has a simple structure, is easy to manufacture and reduces costs.

[0057] (4) Since the diameter of the portion of the planet carrier 221 that supports the driving gear 260 is reduced, a driving gear 260 of a smaller size (smaller diameter) can be used, thereby improving the transmission ratio.

[0058] (5) Under the condition of lower output torque, the bevel gear differential 230 can have lower cost.

[0059] (6) Since the first planetary gear 225 meshes with the ring gear 227 and the second planetary gear 226 meshes with the sun gear 224, the diameter of the second planetary gear 226 can be larger than the diameter of the first planetary gear 225 when the housing 240 has the same size (diameter) (i.e., the ring gear 227 has the same diameter). In this way, a sun gear 224 with a smaller diameter can be used, thereby improving the transmission ratio, and there is no need to increase the intermediate shaft, which can reduce the number of components. Alternatively, the size of the components can be reduced while keeping the transmission ratio unchanged.

[0060] Second embodiment

[0061] Refer to the following Figure 3 A second embodiment of the present invention will be described. Components having the same or similar structures or functions as those in the first embodiment are denoted by the same reference numerals, and detailed description of these components will be omitted.

[0062] In this embodiment, a bridge 200A is provided. The bridge 200A has a structure similar to the bridge 200 in the first embodiment and can obtain similar technical effects as the first embodiment. The difference between the bridge 200A of this embodiment and the bridge 200 of the first embodiment is mainly described below.

[0063] Reference Figure 3 The planet carrier 221 includes an end side located in the axial direction ( Figure 3The first planetary gear 225 and the second planetary gear 226 are mounted on the large diameter portion 221A. The small diameter portion 221B is rotatably mounted on the input shaft 250, and the driving gear 260 is fixedly connected to the small diameter portion 221B.

[0064] It should be understood that the above embodiments are only exemplary and are not intended to limit the present invention. Those skilled in the art may make various modifications and changes to the above embodiments under the guidance of the present invention without departing from the scope of the present invention.

Claims

1. An electric bridge, comprising an electric motor, a planetary gear set, an input shaft, a driving gear and a differential, wherein the output shaft of the electric motor and the input shaft share a common shaft for torsion-proof connection, the common shaft is supported on the housing of the electric bridge via two bearings located at both axial ends of the common shaft and a bearing located at the axial middle position of the common shaft, and the planetary gear set comprises: a sun gear mounted torsionally fixed to the input shaft; a planet carrier rotatably supported on the input shaft relative to the input shaft, the planet carrier being supported on the input shaft via a needle bearing; a first planetary gear and a second planetary gear mounted to the planet carrier, the first planetary gear and the second planetary gear being torsionally connected, the second planetary gear being meshed with the sun gear, and the diameter of the second planetary gear being greater than the diameter of the first planetary gear; as well as a ring gear meshing with the first planetary gears; The driving gear is torsionally mounted to the planet carrier, and the driving gear transmits the rotation of the planet carrier to the differential. The electric bridge is a single-block electric bridge.

2. The bridge according to claim 1, characterized in that: The planetary carrier includes a large diameter portion located at one axial end side and a small diameter portion located at the other axial end side, the first planetary gear and the second planetary gear are mounted on the large diameter portion, the small diameter portion is supported on the input shaft via a needle bearing, and the driving gear is mounted to the small diameter portion to prevent torsion.

3. The bridge according to claim 2, characterized in that: The driving gear is mounted to the small diameter portion via a spline or welded to the small diameter portion.

4. The bridge according to claim 1, characterized in that: The differential comprises: a differential case; a bevel gear set installed in the differential case; and a driven gear anti-torsionally mounted to the differential case, the side gears of the bevel gear set being spline-connected to the side shafts, and the driven gear meshing with the driving gear.

5. The bridge according to claim 1, characterized in that: The first planetary gears and the second planetary gears are offset from each other in the axial direction.

6. The bridge according to claim 1, characterized in that: The first planetary gear and the second planetary gear are formed as one body, and the first planetary gear and the second planetary gear are mounted to the planet carrier via pins and needle bearings.

7. The bridge according to claim 1, characterized in that: The ring gear is fixed to a housing of the electric bridge.

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