Penetrating type coaxial drive axle with four screws and four end covers fastened in penetrating mode

Abstract

A penetrating type coaxial drive axle with four screws and four end covers fastened in a penetrating mode comprises a drive motor with a built-in differential mechanism and speed reducers located on the two sides of the drive motor respectively, and each speed reducer comprises a machine shell with a built-in speed reduction gear set. The machine shell is provided with an end cover assembly used for sealing the reduction gear set in the machine shell. The end cover assembly comprises a front end cover and a rear end cover; the bearing square tube and the rear end cover are cast-welded into a whole; the screw assembly is used for fastening and connecting the end cover assembly. The speed reducer assembly is wrapped and clamped by the front end cover and the rear end cover, the driving motor is wrapped and clamped by the two speed reducers, and the end cover assembly is fixedly connected through the screw assembly, so that the speed reducers, the driving motor and the bearing square tube form a whole, and the screw assembly forms a matrix space. Through the matrix space, the components can be fastened and assembled to form an integral structure, and the bearing capacity and the impact resistance of the drive axle can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of automotive drive, and particularly to a coaxial drive axle with a through-type four-screw and four-end-cap through-fastening structure. Background Art

[0002] A drive axle is located at the end of an automotive transmission system, and can change the speed and torque from the transmission and transmit them to the drive wheels. In the technical solution of the transmission framework of an electric vehicle using a mechanical differential, there are mainly four drive transmission types. One is the vertical transmission mode, that is, the central motor transmits power to the wheels through a transmission, a drive shaft, and a spiral bevel gear with a 90-degree angle. The second is the parallel transmission mode, that is, one or two motors parallel to the axle are installed on the axle in parallel, and the power is transmitted to the wheels through a reduction gear. The third is the hub or wheel-side motor drive mode, where a motor concentric with the wheel or a series of reducers transmits power one-to-one to the wheels. The fourth is the coaxial transmission mode, where a motor is connected in series with a reducer and a differential, and the power is transmitted from the center hole of the motor shaft through two left and right half shafts to the two side wheels in a one-to-two manner. Among the above four power transmission modes, the coaxial transmission mode has the fewest number of components and intermediate links, and the least friction and energy consumption generated during dynamic transmission. However, in terms of structure, it is necessary to connect the motor, reducer, differential, and the load-bearing square tube serving as the axle body through fasteners in multiple modules. Currently, the conventional end-face flange connection is mostly used in the connection method. The structural strength of this connection method is poor, that is, it has deficiencies in fatigue resistance and impact resistance, and is inferior to the vertical motor and parallel motor drive systems with an integrally cast or welded axle body. However, the vertical transmission mode or the parallel transmission mode not only has low efficiency and high energy consumption, but also has a large self-weight. The coaxial transmission mode has higher transmission efficiency, but the reliability of the component end-face connection is poor, which becomes the weakness of this transmission mode.

[0003] Therefore, to overcome this defect, a through-type connection structure and device matching the coaxial motor vehicle drive system are specifically designed. Summary of the Invention

[0004] The object of the present invention is to provide a coaxial drive axle with a through-type four-screw and four-end-cap through-fastening structure to solve the above technical problems. The present invention adopts the following technical solutions:

[0005] A coaxial drive axle with a through-type four-screw and four-end-cap through-fastening structure includes a drive motor with an internal differential, and speed reducers respectively located on both sides of the drive motor. The speed reducer includes a housing with a reduction gear set therein, and the housing is configured with an end-cap assembly for enclosing the reduction gear set within the housing, wherein;

[0006] The end cover assembly includes a front end cover and a rear end cover respectively located at both ends of the housing. The front end cover is located between the drive motor and the speed reducer. It includes a first main body portion that is respectively butt-jointed with the housing and the end face of the drive motor, and also includes a first flange portion that extends in all directions from the first main body portion; the rear end cover is located outside the speed reducer, and the rear end cover includes a second main body portion that is butt-jointed with the end face of the speed reducer and a second flange portion that extends out of the second main body portion;

[0007] Load-bearing square tubes. There are two load-bearing square tubes, which are respectively arranged outside the speed reducer. One end of the load-bearing square tube is rigidly connected to the second main body portion, and the other end extends along the axis direction of the drive motor to form a drive axle wheel end;

[0008] The screw assembly is used to tightly connect the end cover assembly. It includes a plurality of through screws arranged in a matrix and nuts that play a fastening role with the end cover of the speed reducer. The two ends of the through screw respectively penetrate through the first flange portion and then are tightly connected to the second flange portion, and the plurality of through screws and the fastened speed reducer and drive motor form a matrix space in the shape of a prism.

[0009] Further, nuts are arranged on both sides of the first flange portion and the second flange portion. The through screw is tightly connected to the first flange portion and the second flange portion respectively through two nuts.

[0010] Further, a number of first end face teeth arranged at equal intervals in the circumferential direction are provided on the end faces of the two sides of the first main body portion that are respectively butt-jointed with the drive motor and the housing. The length direction of the number of first end face teeth radiates from the center of the first main body portion towards the circumferential direction; on the end faces of the drive motor and the housing that are butt-jointed with the first main body portion, first tooth teeth are formed that cooperate with the first end face teeth and limit the radial displacement of the front end cover.

[0011] Further, a number of second end face teeth arranged at equal intervals in the circumferential direction are formed on the end face of the second main body portion facing the housing. The length direction of the number of second end face teeth radiates from the midline of the second main body portion towards the circumferential direction; on the end face of the housing corresponding to the second main body portion, second tooth teeth are provided that cooperate with the second end face teeth and limit the radial displacement of the rear end cover.

[0012] Further, the cross-section of the first end face teeth and / or the second end face teeth is an isosceles triangle.

[0013] Furthermore, the first main body is respectively formed with a first recessed portion recessed inwardly on the end surfaces facing the drive motor and the casing, the first recessed portion is provided with a side wall inclined inwardly, and the first end face tooth is formed on the side wall of the first recessed portion; the drive motor and the casing are formed with a first convex portion connected to the first recessed portion on the end surfaces corresponding to the first main body, the first convex portion is provided with an outer wall inclined outwardly, and the first tooth is formed on the outer wall of the first convex portion.

[0014] Furthermore, the second main body is respectively formed with a second recessed portion recessed inwardly on the end surface facing the casing, the second recessed portion is provided with a side wall inclined inwardly, and the second end face teeth are formed on the side wall of the second recessed portion; a second convex portion connected to the second recessed portion is formed on the end surface of the casing corresponding to the second main body, the second convex portion is provided with an outer wall inclined outwardly, and the second teeth are formed on the outer wall of the second convex portion.

[0015] Furthermore, the screw assembly also includes a plurality of fasteners, and the plurality of fasteners are used to fasten the first flange portion and the second flange portion together.

[0016] Furthermore, the second main body and the load-bearing square tube are integrally cast and welded.

[0017] The beneficial effects produced by the present invention are as follows:

[0018] The front end cover is located between the drive motor and the reducer housing, and the rear end cover is located between the reducer housing and the load-bearing square pipe. The differential within the drive motor divides into two inner half shafts for gear transmission connection with the reducer. At the same time, the screw assembly consists of multiple through-type screws arranged in a matrix. In this embodiment, four through-type screws are provided, arranged along the edges of the cuboid, such that the projections of the four through-type screws towards the side form four points arranged in a cluster. The two ends of the four through-type screws respectively pass through the first flange portion and are fixedly connected to the second flange portion, thereby connecting the four end covers into a whole. At the same time, by connecting the four end covers, at this time, the front end cover and the rear end cover respectively sandwich the drive motor and the reducer. After the front end cover and the rear end cover are connected by the through-type screws, the reducer, the drive motor, and the load-bearing square pipe form a whole, realizing the integration of the three components. And the through-type screws are arranged in a matrix, so that a matrix space is formed by the multiple through-type screws. Through this matrix space, the above-mentioned components can be assembled into a complete whole. At the same time, the load-bearing capacity between the drive motor, the reducer, and the load-bearing square pipe can also be improved through the matrix space. And within the matrix space, through the mutual cooperation and fastening between the through-type screws and the end covers, the structural strength of the through-type screws enhancing and superimposing each other can be improved, ensuring the load-bearing and anti-fatigue capabilities of the drive axle. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a structural schematic diagram of the present invention.

[0020] Figure 2 is an exploded structural schematic diagram of the present invention.

[0021] Figure 3 is Figure 2 a partial enlarged schematic diagram of part A in

[0022] Figure 4 is Figure 2 a partial enlarged schematic diagram of part B in

[0023] In the figure: 100 - drive motor; 110 - reducer; 121 - inner half shaft; 200 - end cover assembly; 210 - front end cover; 220 - rear end cover; 211 - first main body part; 212 - first flange part; 221 - second main body part; 222 - second flange part; 300 - load-bearing square pipe; 310 - wheel end; 400 - screw assembly; 410 - through-type screw; 411 - nut; 213 - first end face tooth; 101 - first tooth; 223 - second end face tooth; 111 - second tooth; 215 - first recess; 102 - first outer convex part; 225 - second recess; 112 - second outer convex part; 412 - fastener; 113 - housing; 114 - reduction gear set. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] For the convenience of understanding by those skilled in the art, the present invention will be further described below in conjunction with embodiments and the accompanying drawings. The content mentioned in the embodiments does not limit the present invention. The present invention will be described in detail below with reference to the accompanying drawings.

[0025] This embodiment provides a coaxial drive axle with a through-type four-screw and four-end-cap through-fastening. By providing an end-cap assembly 200 composed of four end caps and a screw assembly 400 composed of a plurality of through-type screws 410, the drive motor 100 with an in-built differential, the speed reducer 110, and the load-bearing square tube 300 arranged coaxially are set to form a firm drive axle. The speed reducer 110 is clamped by the front end cap 210 and the rear end cap 220, and the drive motor 100 is clamped, realizing the integration of the three components. The through-type screw assembly 400 penetrates and connects the end-cap assembly 200, and the through-type screws 410 are arranged in a matrix, so that a matrix space is formed by the plurality of through-type screws 410. The through-type screws 410 strengthen the structural strength of each other, and at the same time, the weight can be lightened, and the motor power can be increased within the effective space. At the same time, by designing the structure of each end-cap end face, the ability of the drive axle to bear the load and withstand vibration can be further improved, ensuring high load-bearing capacity and anti-impact ability.

[0026] As Figures 1-4As shown in the figure, a coaxial drive axle with a through-type four-screw and four-end-cover through-fastening provided in this embodiment includes a drive motor 100 with an in-built differential, speed reducers 110 located on both sides of the drive motor 100, and inner half shafts 121 extending from both ends of the drive motor 100 and respectively connected to the speed reducers 110 by gears. Among them, the speed reducer includes a housing with a deceleration gear set built therein, and an end-cover assembly provided at both ends of the housing to enclose the deceleration gear set within the housing. At the same time, this drive axle also includes a load-bearing square tube and a screw assembly. Specifically, the end-cover assembly 200 includes a front end cover 210 and a rear end cover 220. The front end cover and the rear end cover are located on both sides of the housing and enclose both ends of the housing, enclosing the deceleration gear set within the housing. At the same time, the front end cover 210 is located between the drive motor 100 and the housing 113, and it includes a first main body portion 211 respectively docked with the end faces of the housing 113 and the drive motor 100, and also includes a first flange portion 212 extending in all directions from the first main body portion 211; the rear end cover 220 is located outside the housing 113, and the rear end cover 220 includes a second main body portion 221 docked with the end face of the housing 113 and a second flange portion 222 extending from the second main body portion 221; there are two load-bearing square tubes 300, and the two load-bearing square tubes 300 are respectively located outside the two speed reducers 110. One end of the load-bearing square tube 300 is rigidly connected to the second main body portion 221, and the other end extends along the axis direction of the drive motor 100 to form the wheel end 310 of the drive axle; the screw assembly 400 is used to tightly connect the end-cover assembly 200, and it is composed of a plurality of through-type screws 410 arranged in a matrix and nuts 411 that play a fastening role with the speed reducer end covers. Both ends of the through-type screw 410 respectively penetrate through the first flange portion 212 and are then tightly connected to the second flange portion 222, and the plurality of through-type screws 410 and the speed reducers and drive motors to be fastened form a matrix space in the shape of a prism. Through this matrix space, the above-mentioned components can be partitioned and tightly assembled, and a rigid integral structure can be formed, which can improve the load-bearing capacity and impact resistance of the drive axle.

[0027] During operation, the front end cover 210 is located between the drive motor 100 and the housing 113, and the rear end cover 220 is located between the housing 113 and the load-bearing square pipe 300. The inner half shaft 121 within the drive motor 100 is in gear transmission connection with the speed reducer 110. It can be understood that teeth can be provided on the end of the inner half shaft 121 connected to the speed reducer 110, or a gear can be fixedly installed to achieve the gear transmission connection with the speed reducer 110. At the same time, an outer half shaft extends from the output end of the speed reducer 110 and extends within the load-bearing direction to the wheel end 310 to transmit the rotational speed and torque to the wheel assembled on the wheel end 310. In this way, there is a transmission system inside the drive axle to keep the drive axle body stable. At the same time, the screw assembly 400 includes a plurality of through screws 410 arranged in a matrix. In this embodiment, four through screws 410 are provided and arranged along the edges of the cuboid, so that the projections of the four through screws 410 towards the side form four points arranged in a cluster. After the four through screws 410 connect the four end covers, the four through screws 410 form a cubic matrix space. The two ends of the four through screws 410 respectively penetrate through the first flange portion 212 and are fixedly connected to the second flange portion 222, thereby connecting the four end covers into a whole. At the same time, by connecting the four end covers, at this time, the two front end covers 210 clamp the drive motor 100, the two rear end covers 220 clamp the housing 113, and at the same time, the two rear end covers clamp the housing and the drive motor as a whole. That is to say, the front end cover and the rear end cover clamp the speed reducer assembly into a whole, and the two speed reducers clamp the drive motor into a whole. After the front end cover 210 and the rear end cover 220 are connected by the through screws 410, the speed reducer 110, the drive motor 100, and the load-bearing square pipe 300 form a rigid integral structure, realizing the integration of the three components. And the through screws 410 are arranged in a matrix, so that the speed reducer and the drive motor fastened by the plurality of through screws 410 form a matrix space. Through this matrix space, the above components can be assembled into a rigid whole. At the same time, the load-bearing capacity between the drive motor 100, the speed reducer 110, and the load-bearing square pipe 300 can be improved through the matrix space. And within the matrix space, through the mutual cooperation between the through screws 410 and the end covers, the strength of the structure mutually enhanced between the through screws 410 can be improved, ensuring the load-bearing capacity of the drive axle. It should be noted that four through screws 410 are provided in this embodiment. In other embodiments, a plurality of through screws 410 can also be provided. The plurality of through screws 410 are arranged side by side to form a matrix space in the shape of a prism. Thus, under the combination of this matrix space, the above-mentioned various parts can be formed into a whole, and the load-bearing capacity of the drive axle can be improved under the joint action of the through screws 410 in this matrix space.At this time, the front end cover is located between the drive motor and the housing of the speed reducer. It is not only the end cover of the speed reducer, but also a structural member that clamps the drive motor. Similarly, the rear end cover is located between the housing of the speed reducer and the load-bearing square pipe. It is both the end cover of the speed reducer and a structural member that connects the load-bearing square pipe. The screw assembly penetrates and connects the load-bearing square pipe, the speed reducer, and the drive motor through the four end covers, making the three form a rigid whole, thereby improving the load-bearing capacity of the drive axle.

[0028] In this embodiment, in order to ensure the load-bearing capacity between the rear end cover 220 and the load-bearing square pipe 300, the rear end cover 220 and the load-bearing square pipe 300 are integrally formed by a casting and welding process. After the four end covers are connected through the through-type screw 410, the integrity and rigidity among the end cover, the load-bearing square pipe 300, the speed reducer 110, and the drive motor 100 can be ensured, and its load-bearing capacity can be guaranteed.

[0029] To ensure the fixation when the through-screw is connected to the two end covers, nuts 411 are respectively arranged on both sides of the first flange 212 and the second flange portion 222. The through-type screw 410 is tightly connected to the first flange 212 and the second flange portion 222 through the two nuts 411. That is to say, after one end of the through-type screw 410 penetrates the first flange portion 212, the first flange portion 212 is tightened through the two nuts 411, so that the front end cover 210 clamps and fixes the drive motor 100. After the end of the through-type screw 410 penetrates the second flange portion 222, it is tightened through the two nuts 411 arranged on both sides of the second flange portion 222, thereby ensuring the firmness of the through-type screw 410 on the first flange portion 212 and the second flange portion 222, and at the same time, locking and fixing the drive motor 100, the speed reducer 110, and the load-bearing square pipe 300 into a rigid whole.

[0030] In this embodiment, in order to further improve the load-bearing capacity and impact resistance of the drive axle, and to prevent the drive axle from displacing radially at the docking position between the end cover and the speed reducer 110 or the drive motor 100 when bearing a load, as Figures 2-4 shown, a number of first end-face teeth 213 arranged at equal intervals in the circumferential direction are provided on the end faces of the two sides of the first main body portion 211 that are respectively docked with the drive motor 100 and the housing 113. The length direction of the number of first end-face teeth 213 radiates from the center of the first main body portion 211 towards the circumferential direction; on the end faces of the drive motor 100 and the housing 113 that are docked with the first main body portion 211, first tooth teeth 101 that cooperate with the first end-face teeth 213 and limit the radial displacement of the front end cover 210 are formed.

[0031] Similarly, a plurality of second end face teeth 223 arranged at equal intervals in the circumferential direction are formed on the end face of the second main body portion 221 facing the housing 113, and the length directions of the plurality of second end face teeth 223 radiate from the center line of the second main body portion 221 toward the circumferential direction; a second tooth 111 is provided on the end face of the housing 113 corresponding to the second main body portion 221, which cooperates with the second end face teeth 223 and limits the displacement of the rear end cover 220 in the radial direction.

[0032] When the drive axle is under load, especially when it is subjected to impact force, at the end face where the end cover and the housing 113 of the reducer 110 or the drive motor 100 are connected to each other, the first end face teeth 213 are meshed with the first teeth 101, and the second end face teeth 223 are meshed with the second teeth 111. At the same time, since the length direction of the first end face teeth 213 and the second end face teeth 223 radiates from the center of the end cover toward the circumferential direction, after the end cover and the drive motor 100 or the reducer 110 are connected to each other, the first end face teeth 213 are meshed with the first teeth 101, and the second end face teeth 223 are meshed with the second teeth 111. The meshing surface will be used to bear the radial load on the drive axle and disperse the load through the meshing surface. At the same time, it can limit the radial movement of the end cover and the drive motor 100 and the reducer 110 at the connection surface, thereby improving the load-bearing capacity and impact resistance of the drive axle. It is worth noting that since the first end face teeth 213 and the second end face teeth 223 are both radiated from the center toward the four-axis direction, that is, the intersection of the extension line of one end of the end face teeth is located at the center of the end cover, and the other end extends in the diameter direction, so that when the end face teeth and the teeth are meshed, the meshing surface can bear the radial impact or load in any direction of the circumference and limit the radial displacement. At the same time, it is worth noting that by providing the end face teeth and the teeth, in the process of assembling the drive axle, the end face teeth and the teeth can be meshed with each other to position when assembling the drive motor, the end cover and the reducer, thereby ensuring the coaxiality of the drive axle.

[0033] In this embodiment, in order to ensure the load-bearing capacity between the face teeth and the teeth, the cross section of the first face teeth 213 and / or the second face teeth 223 is an isosceles triangle.

[0034] In this embodiment, in order to further improve the bearing capacity of the drive axle and the stability after the drive motor 100, the reducer 110 and the load-bearing square tube 300 are combined by the screw assembly. A first recessed portion 215 recessed toward the inside is formed on the end surface of the first main body 211 facing the drive motor 100 and the housing 113 of the reducer 110, and the first recessed portion 215 is provided with a side wall inclined toward the inside, and the first end face tooth 213 is formed on the side wall of the first recessed portion 215; a first convex portion 102 connected to the first recessed portion 215 is formed on the end surface of the housing 113 of the drive motor 100 and the reducer 110 corresponding to the first main body 211, and the first convex portion 102 is provided with an outer wall inclined toward the outside, and the first tooth 101 is formed on the outer wall of the first convex portion 102.

[0035] At the same time, the second main body 221 is respectively formed with a second recessed portion 225 recessed toward the inside on the end surface of the casing 113 of the reducer 110, the second recessed portion 225 is provided with a side wall inclined toward the inside, and the second end face tooth 223 is formed on the side wall of the second recessed portion 225; the casing 113 is formed with a second convex portion 112 connected to the second recessed portion 225 on the end surface corresponding to the second main body 221, the second convex portion 112 is provided with an outer wall inclined toward the outside, and the second tooth 111 is formed on the outer wall of the second convex portion 112.

[0036] After the end cover assembly 200 is locked by the screw assembly 400, the first outer protrusion 102 formed on the drive motor 100 and the housing 113 is embedded in the first recessed portion 215 formed on the front cover 210. At the same time, the first outer protrusion 102 located on the side of the reducer 110 facing the rear cover 220 is embedded in the second inner recessed portion formed on the rear cover 220. In other words, the outer protrusions of the reducer 110 and the drive motor 100 are respectively covered by the inner recessed portions. In the process of locking by the screw assembly 400, the ends of the drive motor 100 and the reducer 110 can be covered in the inner recessed portions. Through the axial embedded structure, the stability after connection by the screw assembly 400 can be improved, the integrity of the drive axle can be ensured, and the load-bearing capacity of the drive axle can be effectively improved.

[0037] In this embodiment, in order to further enhance the connection stability between the front end cover 210 and the rear end cover 220, the screw assembly 400 further includes a plurality of fasteners 412, and the plurality of fasteners 412 are used to fasten and connect the first flange portion 212 and the second flange portion 222. In this embodiment, the fastener 412 is composed of bolts. By arranging a plurality of bolts on the first flange portion 212 and the second flange portion 222 for further connection, it can ensure that the end cover assemblies 200 located on one side of the drive motor 100 form a complete whole, and the speed reducer 110 is clamped inside thereof. Through the above structure, the integrity of the drive axle can be enhanced, enabling it to have a higher load-bearing capacity.

[0038] The above are only preferred embodiments of the present invention, and there is no limitation to the present invention in any form. Although the present invention is disclosed above in preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art, without departing from the scope of the technical solution of the present invention, when making some changes or modifications using the above-disclosed technical content as equivalent change equivalent embodiments, but as long as it does not depart from the content of the technical solution of the present invention, any simple modification, equivalent change and modification made to the above embodiments according to the technical means of the present invention shall fall within the scope of the technical solution of the present invention.

Claims

1. A through-type four-screw four-end cover through-fastened coaxial drive axle, comprising a drive motor with a built-in differential, and reducers located on both sides of the drive motor, wherein the reducer comprises a housing with a built-in reduction gear set, and the housing is provided with an end cover assembly for enclosing the reduction gear set within the housing, characterized in that ； The end cover assembly includes a front cover and a rear cover respectively located at both ends of the housing, the front cover is located between the drive motor and the reducer, and includes a first main body portion respectively connected to the housing and the end surface of the drive motor, and also includes a first flange portion extending in all directions along the first main body portion; the rear cover is located outside the reducer, and the rear cover includes a second main body portion connected to the end surface of the reducer and a second flange portion extending from the second main body portion; A load-bearing square tube, wherein there are two load-bearing square tubes, which are respectively arranged outside the reducer, one end of which is rigidly connected to the second main body, and the other end of which is extended along the axis direction of the drive motor to form a drive axle wheel end; A screw assembly is used to fasten the end cover assembly, and includes a plurality of through-type screws arranged in a matrix and a nut that fastens the reducer end cover. Both ends of the through-type screws respectively penetrate the first flange portion and are fastened to the second flange portion. The plurality of through-type screws and the fastened reducer and drive motor form a matrix space with a polygonal column structure.

2. A through-type four-screw four-end-cap through-fastened coaxial drive axle according to claim 1, characterized in that: Nuts are provided on both sides of the first flange portion and the second flange portion, and the through-type screw is respectively fastened to the first flange portion and the second flange portion through two nuts.

3. The through-type four-screw four-end-cap through-fastened coaxial drive axle according to claim 1, characterized in that: A plurality of first end face teeth arranged at equal intervals in the circumferential direction are provided on the end faces on both sides of the first main body that are respectively connected to the drive motor and the casing, and the length directions of the plurality of first end face teeth radiate from the center of the first main body toward the circumferential direction; first teeth that cooperate with the first end face teeth and limit the radial displacement of the front end cover are formed on the end faces that are connected to the drive motor, the casing and the first main body.

4. The through-type four-screw four-end-cap through-fastened coaxial drive axle according to claim 3, characterized in that: A plurality of second end face teeth arranged at equal intervals in the circumferential direction are formed on the end face of the second main body portion facing the housing, and the length directions of the plurality of second end face teeth radiate from the center line of the second main body portion toward the circumferential direction; second teeth that cooperate with the second end face teeth and limit the displacement of the rear end cover in the radial direction are arranged on the end face of the housing corresponding to the second main body portion.

5. A through-type coaxial drive axle with four screws and four end covers through-fastened according to any one of claims 3-4, characterized in that: The cross section of the first face gear and / or the second face gear is an isosceles triangle.

6. The through-type four-screw four-end-cap through-fastened coaxial drive axle according to claim 3, characterized in that: The first main body has first recessed portions recessed inwardly formed on end surfaces facing the drive motor and the housing respectively, the first recessed portions are provided with side walls inclined inwardly, and the first end face teeth are formed on the side walls of the first recessed portions; the drive motor and the housing have first convex portions connected to the first recessed portions formed on end surfaces corresponding to the first main body, the first convex portions are provided with outer walls inclined outwardly, and the first teeth are formed on the outer walls of the first convex portions.

7. The through-type four-screw four-end-cap through-fastened coaxial drive axle according to claim 4, characterized in that: The second main body portion is respectively formed with a second recessed portion recessed inwardly on the end surface facing the casing, the second recessed portion is provided with a side wall inclined inwardly, and the second end face teeth are formed on the side wall of the second recessed portion; a second convex portion connected to the second recessed portion is formed on the end surface of the casing corresponding to the second main body portion, the second convex portion is provided with an outer wall inclined outwardly, and the second teeth are formed on the outer wall of the second convex portion.

8. The through-type four-screw four-end-cap through-fastened coaxial drive axle according to claim 1, characterized in that: The screw assembly also includes a plurality of fasteners, and the plurality of fasteners are used to fasten and connect the first flange portion and the second flange portion.

9. The through-type four-screw four-end-cap through-fastened coaxial drive axle according to claim 1, characterized in that: The second main body and the load-bearing square tube are integrally cast and welded.

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