Shaft grounding structure and electric driving system

Abstract

The utility model provides a shaft grounding structure and an electric driving system. The shaft grounding structure may include an output shaft and a housing. One end of the output shaft is provided with a circular truncated cone-shaped concave cavity, and the radius of the inner wall of the concave cavity is gradually increased along with the opening close to the concave cavity in the axial direction of the output shaft. A grounding element and a spring are installed in the shell, an abutting face is formed at the axial bottom of the concave cavity, the grounding element is configured to extend into the concave cavity and abut against the abutting face under the action of the spring, and the output shaft is electrically connected to the shell through the grounding element. And a spacing space is formed between the grounding element and the inner wall, so that after the output shaft rotates, lubricating oil on the inner wall can flow out of the concave cavity along the inner wall under the action of centrifugal force.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of automobile design and manufacturing, and in particular to an axle grounding structure and an electric drive system. BACKGROUND

[0002] In an electric drive system, in order to eliminate the safety hazards such as electric corrosion of the output shaft of the motor and the gearbox, some technologies will connect the output shaft with the shell to achieve the grounding effect. The output shaft and the shell will rotate relative to each other, and the axle grounding structure needs to be able to withstand the relative rotation and maintain the electrical connection between the output shaft and the shell.

[0003] More specifically, four types of axle grounding structures are known.

[0004] Solution one: as shown in US2021391680A1, a conductive brush is installed on the cylindrical surface of the output shaft, and the electrical connection between the output shaft and the shell is achieved through the brush.

[0005] Solution two: as shown in DE102021210335A1, a conductive rod is installed on the end of the output shaft, and the conductive rod is in contact with the shell via a spring.

[0006] Solution three: a conductive oil seal is installed on the cylindrical surface of the output shaft, and the electrical connection between the output shaft and the shell is achieved through the oil seal.

[0007] Solution four: a conductive bearing is used, for example, a conductive grease is arranged inside the bearing or a conductive part is integrated in the bearing.

[0008] For solution one, in order to ensure good contact between the brush and the output shaft, silver is usually used inside the brush, so the cost of solution one is high. For other solutions, due to the accumulation of grease, the generation of oil film, or the low conductivity of the oil seal, the electrical connection between the output shaft and the shell is unstable and ineffective. In addition, the friction between the output shaft and the shell in each solution is large, which reduces the system efficiency. UTILITY MODEL CONTENT

[0009] In order to solve or alleviate at least one problem mentioned in the background art, the present application provides an axle grounding structure and an electric drive system.

[0010] The axle grounding structure provided by the embodiment of the present application comprises:

[0011] an output shaft, one end of the output shaft is provided with a concave cavity in the shape of a circular truncated cone, and the radius of the inner wall of the concave cavity gradually increases as it approaches the opening of the concave cavity in the axial direction of the output shaft;

[0012] The shell is internally provided with a grounding element and a spring, an axial bottom of the cavity is formed with an abutting surface, the grounding element is configured to extend into the cavity and press against the abutting surface under the action of the spring, the output shaft is electrically connected to the shell through the grounding element, and a spacing is formed between the grounding element and the inner wall, so that lubricating oil on the inner wall can flow out of the cavity along the inner wall under the action of centrifugal force after the output shaft rotates.

[0013] In at least one embodiment, a radially outer side of an open end of the cavity is provided with an annular output shaft end surface, a side of the shell facing the output shaft is provided with an annular shell end surface, the output shaft end surface and the shell end surface are configured to have an axial spacing, and the output shaft end surface is provided with an output shaft oil guide groove extending in a radial direction.

[0014] In at least one embodiment, the axial spacing is not more than 1 mm.

[0015] In at least one embodiment, a radially inner side of the shell end surface is provided with a shell first groove, the shell first groove is embedded in the shell in an axial direction and extends in a circumferential direction of the output shaft to form an annular groove.

[0016] In at least one embodiment, the inner wall comprises a first inner wall and a second inner wall which are axially connected, a taper of the second inner wall is greater than a taper of the first inner wall, and the output shaft oil guide groove is connected to the second inner wall.

[0017] In at least one embodiment, the shell comprises a shell protruding portion extending into the cavity, the grounding element is partially mounted in the shell protruding portion, an outer wall of the shell protruding portion is provided with a shell second groove, and the shell second groove extends in a circumferential direction of the shell protruding portion to form an annular groove.

[0018] In at least one embodiment, the shaft grounding structure comprises:

[0019] A grounding element sleeve in which the grounding element and the spring are arranged;

[0020] An abutting plate, one end of the grounding element sleeve is connected to the abutting plate, and one end of the grounding element is pressed against the abutting plate;

[0021] A bolt which is threadedly connected to the shell, the shell is provided with a locating shoulder for the abutting plate, and the bolt presses the abutting plate against the locating shoulder for the abutting plate.

[0022] In at least one embodiment, the shaft grounding structure includes a bearing, the output shaft includes an output shaft locating shoulder, the housing includes a housing locating shoulder, an inner race of the bearing abuts the output shaft locating shoulder, an outer race of the bearing abuts the housing locating shoulder to control a distance between the output shaft end face and the housing end face, and a transition space is formed between the bearing and the output shaft oil guide groove.

[0023] Embodiments of the present application provide an electric drive system including a shaft grounding structure as previously described.

[0024] In at least one embodiment, the electric drive system includes an electric drive system chamber having lubricating oil, and the output shaft is at least partially located in the electric drive system chamber.

[0025] The present application provides a circular truncated cone-shaped recess at one end of the output shaft, so that lubricating oil (if any) on the inner wall of the recess can be thrown out under the action of centrifugal force, reducing the influence of lubricating oil on the contact resistance between the output shaft and the grounding rod. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 A cross-sectional view of a shaft grounding structure according to an embodiment of the present application is shown.

[0027] Figure 2 A partial enlarged view of the housing end face and the output shaft end face position of the shaft grounding structure in Figure 1

[0028] Figure 3 A perspective view of an end of an output shaft of a shaft grounding structure according to an embodiment of the present application is shown.

[0029] Figure 4 A perspective view of an end of a housing of a shaft grounding structure according to an embodiment of the present application is shown.

[0030] REFERENCE NUMERALS

[0031] 100 output shaft

[0032] 110 recess

[0033] 120 inner wall

[0034] 121 first inner wall

[0035] 122 second inner wall

[0036] 130 abutting surface

[0037] 140 spacing space

[0038] 150 output shaft end face

[0039] ​160 Output shaft oil guide groove

[0040] 170 Output shaft locating shoulder

[0041] 200 housing

[0042] 210 Grounding element

[0043] 220 spring

[0044] 230 Housing end face

[0045] 240 First groove of the shell

[0046] 250 Housing protrusion

[0047] 260 Second groove of the housing

[0048] 270 Positioning shoulder for contact plate

[0049] 280 Housing positioning shoulder

[0050] 300 axial spacing

[0051] 410 Grounding element set

[0052] 420 impact plate

[0053] 430 bolts

[0054] 440 gasket

[0055] 500 bearing

[0056] 510 Inner Circle

[0057] 520 outer ring

[0058] 600 Transition Space Detailed Implementation

[0059] Exemplary embodiments of this application are described below with reference to the accompanying drawings. It should be understood that these specific descriptions are for teaching those skilled in the art how to implement this application only, and are not intended to exhaustively describe all possible methods of this application, nor to limit the scope of this application.

[0060] This application provides a shaft grounding structure and an electric drive system.

[0061] See Figure 1 The shaft grounding structure may include an output shaft 100 and a housing 200.

[0062] One end of the output shaft 100 (e.g.) Figure 1 A frustum-shaped cavity 110 is provided at the right end of the viewing angle. As the opening of the cavity 110 approaches in the axial direction, the radius of the inner wall 120 of the cavity 110 gradually increases.

[0063] The housing 200 can be provided with a grounding element 210 and a spring 220, and the axial bottom of the recess 110 is formed with an abutting surface 130. The grounding element 210 is configured to extend into the recess 110 and press against the abutting surface 130 under the action of the spring 220, so that the output shaft 100 can be electrically connected to the housing 200 through the grounding element 210. The abutting surface 130 and the grounding element 210 can be in surface contact.

[0064] The grounding element 210 and the inner wall 120 have a spacing space 140 therebetween, so that the lubricating oil on the inner wall 120 can flow out of the recess 110 along the inner wall 120 under the action of centrifugal force after the output shaft 100 rotates.

[0065] It should be understood that the lubricating oil in the reduction gearbox may, for example, enter the position of the output shaft 100 and the grounding element 210, affect the contact resistance of the output shaft 100 and the grounding element 210, and further affect the grounding effect of the output shaft 100. The present application provides the recess 110 at one end of the output shaft 100, and the inner wall 120 of the recess 110 is formed in a tapered shape, so that the lubricating oil on the inner wall 120 can be thrown out under the action of centrifugal force, reducing the influence of the lubricating oil on the contact resistance. Accordingly, the grounding element 210 can use a relatively inexpensive carbon rod, which can reduce costs compared to adding materials such as silver that facilitate electrical conduction. The oil film between the grounding element 210 and the output shaft 100 can be reduced to stabilize the electrical connection, so the spring force of the spring 220 can also be set to be relatively low, thereby reducing the friction between the output shaft 100 and the grounding element 210 and improving the efficiency of the reduction gearbox or electric drive system.

[0066] Referring to Figures 2 to 4 In one embodiment, the recess 110 has an annular output shaft end face 150 radially outside the open end, and the housing 200 has an annular housing end face 230 on the side facing the output shaft 100, and the output shaft end face 150 and the housing end face 230 are configured to have an axial spacing 300, so that a chamber is formed between the output shaft 100 and the housing 200. The output shaft end face 150 is provided with one or more radially extending output shaft oil guide grooves 160, and the lubricating oil in the chamber can exit the chamber through the output shaft oil guide grooves 160.

[0067] The distance between the output shaft end face 150 and the housing end face 230 can be controlled by controlling the position of the output shaft 100. For example, the axial spacing 300 between the output shaft end face 150 and the housing end face 230 can be less than 1 mm (especially referring to the spacing at the position where the output shaft oil guide grooves 160 are not provided). Figure 3 The output shaft end face 150 can be provided with a plurality of output shaft oil guide grooves 160.

[0068] The application forms a relatively closed chamber between the output shaft 100 and the housing 200, preventing external lubricating oil from entering the connection position of the output shaft 100 and the grounding element 210. Compared with the dynamic seal, the application provides the end face close to the oil throwing of the conical surface, which is simple in concept and easy to realize. Similarly, the grounding element 210 can be relatively low in cost, and the friction between the output shaft 100 and the grounding element 210 is low, which is beneficial to improve the efficiency of the reduction gearbox or the electric drive system.

[0069] Referring to Figure 2 、 Figure 4 In one embodiment, the radially inner side of the housing end face 230 is provided with a housing first groove 240, which is embedded in the housing 200 in the axial direction and extends in the circumferential direction to form an annular groove. It should be understood that external lubricating oil can enter the recess 110 through the output shaft oil guide groove 160. The housing first groove 240 can accommodate the lubricating oil entering the chamber from the outside, preventing the lubricating oil from further flowing into the grounding element 210 and the position where the abutting surface 130 is located. Moreover, since the housing 200 does not rotate, the lubricating oil contained in the housing first groove 240 will also drip back to the output shaft oil guide groove 160 under the action of gravity, and then be thrown out of the recess 110.

[0070] Referring to Figure 2 、 Figure 3 In one embodiment, the inner wall 120 of the output shaft 100 can include a first inner wall 121 and a second inner wall 122 connected in the axial direction, the taper (upper base diameter-lower base diameter ÷ height) of the second inner wall 122 is greater than that of the first inner wall 121, and the output shaft oil guide groove 160 is connected to the second inner wall 122. The application sets the inner wall 120 to be a two-section design with different tapers, and the second inner wall 122 at the opening has a larger taper, which is beneficial to throw out the lubricating oil, and the first inner wall 121 close to the bottom has a smaller taper, which is beneficial to reduce the radial size of the recess 110.

[0071] It can be understood that the height in the taper formula refers to the size of the first inner wall 121 and the second inner wall 122 in the axial direction of the output shaft 100. The taper also represents the angle of the taper angle formed by the first inner wall 121 and the second inner wall 122 and the axial direction of the output shaft 100.

[0072] Referring to Figure 2 In one embodiment, the housing 200 includes a housing protruding portion 250 extending into the recess 110, the grounding element 210 is partially mounted in the housing protruding portion 250, and the outer wall of the housing protruding portion 250 is provided with a housing second groove 260 extending in the circumferential direction of the housing protruding portion 250 to form an annular groove. Similarly, the housing second groove 260 can also accommodate the lubricating oil entering the chamber from the outside, preventing the lubricating oil from further flowing into the grounding element 210 and the position where the abutting surface 130 is located.

[0073] The second groove 260 of the shell can be arranged at the root of the shell protruding part 250 (close to the side of the first groove 240 of the shell), and the lubricating oil contained in the second groove 260 of the shell can also drip back to the inner wall 120 of the cavity 110 and the oil guide groove 160 of the output shaft under the action of gravity, and then be thrown out of the cavity 110.

[0074] Referring to Figure 2 In an embodiment, the shaft grounding structure includes a grounding element sleeve 410, a contact plate 420, and a bolt 430. The grounding element 210 and the spring 220 are arranged in the grounding element sleeve 410, which provides mounting space for the grounding element 210 and the spring 220, and can prevent the lubricating oil in the cavity 110 from directly falling on the grounding element 210.

[0075] One end of the grounding element sleeve 410 is connected to the contact plate 420, and one end of the grounding element 210 is pressed against the contact plate 420. The material of the contact plate 420 can be metal.

[0076] The bolt 430 is threadedly connected to the shell 200, and the shell 200 is provided with a positioning shoulder 270 for the contact plate, and the bolt 430 presses the contact plate 420 against the positioning shoulder 270 for the contact plate. A gasket 440 can also be arranged between the bolt 430 and the shell 200 in the axial direction.

[0077] Referring to Figure 1 In an embodiment, the shaft grounding structure includes a bearing 500, the output shaft 100 includes an output shaft positioning shoulder 170, the shell 200 includes a shell positioning shoulder 280, the inner ring 510 of the bearing 500 abuts against the output shaft positioning shoulder 170, and the outer ring 520 of the bearing 500 abuts against the shell positioning shoulder 280, so that the output shaft 100 is mounted to the shell 200 via the bearing 500, thereby controlling the axial position of the output shaft 100 and controlling the axial spacing 300 between the output shaft end face 150 and the shell end face 230. A transition space 600 can be formed between the bearing 500 and the oil guide groove 160 of the output shaft. The axial dimension of the transition space 600 is significantly greater than the axial dimension of the spacing 300, so as to accommodate the lubricating oil.

[0078] The electric drive system provided in the present application can include the shaft grounding structure as described above. The electric drive system can also include an electric drive system chamber containing lubricating oil, and the output shaft 100 is at least partially located in the electric drive system chamber.

[0079] The above describes the preferred embodiments of the present application, and it should be pointed out that those skilled in the art can make several improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A shaft grounding structure, characterized by, The application relates to an axle grounding structure of an electric drive system. The output shaft is provided with a circular truncated-cone-shaped recess at one end, the radius of the inner wall of the recess gradually increases as the opening of the recess approaches in the axial direction of the output shaft; The shell is provided with a grounding element and a spring, the axial bottom of the recess is formed with an abutting surface, the grounding element is configured to extend into the recess and abut against the abutting surface under the action of the spring, the output shaft is electrically connected to the shell through the grounding element, and a spacing space is formed between the grounding element and the inner wall, so that lubricating oil on the inner wall can flow out of the recess along the inner wall under the action of centrifugal force after the output shaft rotates.

2. The axle grounding structure according to claim 1, characterized by The radial outer side of the opening end of the recess is provided with an annular output shaft end face, the side of the shell facing the output shaft is provided with an annular shell end face, the output shaft end face and the shell end face are configured to have an axial spacing, and the output shaft end face is provided with an output shaft oil guide groove extending in the radial direction.

3. The axle grounding structure according to claim 2, characterized by The axial spacing is not more than 1 mm.

4. The axle grounding structure according to claim 2, characterized by The radial inner side of the shell end face is provided with a shell first groove, the shell first groove is embedded in the shell in the axial direction and extends in the circumferential direction of the output shaft to form an annular groove.

5. The axle grounding structure according to claim 2, characterized by The inner wall comprises a first inner wall and a second inner wall connected in the axial direction, the taper of the second inner wall is greater than that of the first inner wall, and the output shaft oil guide groove is connected to the second inner wall.

6. The axle grounding structure according to claim 1, characterized by The shell comprises a shell protruding part extending into the recess, the grounding element is partially mounted in the shell protruding part, and the outer wall of the shell protruding part is provided with a shell second groove extending in the circumferential direction of the shell protruding part to form an annular groove.

7. The axle grounding structure according to claim 1, characterized by The axle grounding structure comprises: A grounding element sleeve in which the grounding element and the spring are arranged; An abutting plate, one end of the grounding element sleeve is connected to the abutting plate, and one end of the grounding element abuts against the abutting plate; A bolt threadedly connected to the shell, the shell is provided with a locating shoulder for the abutting plate, and the bolt abuts the abutting plate against the locating shoulder for the abutting plate.

8. The axle grounding structure according to claim 2, characterized by The axle grounding structure comprises a bearing, the output shaft comprises an output shaft locating shoulder, the shell comprises a shell locating shoulder, the inner ring of the bearing abuts against the output shaft locating shoulder, and the outer ring of the bearing abuts against the shell locating shoulder, so as to control the distance between the output shaft end face and the shell end face, and a transition space is formed between the bearing and the output shaft oil guide groove.

9. An electric drive system, characterized by The axle grounding structure comprises the axle grounding structure of any one of claims 1 to 8.

10. The electric drive system of claim 9, wherein, The electric drive system comprises an electric drive system cavity with lubricating oil, and the output shaft is at least partially located in the electric drive system cavity.

Images