Central drive electric drive system

Abstract

The present invention discloses a central drive electric drive system, including a motor, a speed change mechanism and a wheel hub drive sleeve, wherein the speed change mechanism is mounted on the motor shaft of the motor, the wheel hub drive sleeve is rotatably mounted on the motor shaft of the motor and is located between the speed change mechanism and the rotor of the motor, and the motor shaft transmits power to the wheel hub drive sleeve through the speed change mechanism. Compared with the central drive electric drive system designed by the inventor team in the past, the central drive electric drive system adopting the above technical solution effectively solves the problems of poor mutual independence of the motor assembly, the reduction box and the wheel hub structure, difficulty in disassembly and assembly, overlapping connection and fixing methods of parts, and many parts; it is not only more convenient for assembly, disassembly and maintenance, but also can reduce volume and weight, reduce manufacturing costs, achieve "extreme simplicity", and further improve reliability and controllability, greatly enhance product competitiveness, and make it easier to promote and use, making it easier to accept in the market.

Description

Technical Field

[0001] The present invention relates to the technical field of electric drive systems, and in particular to a central drive type electric drive system. Background Art

[0002] As environmental regulations become increasingly stringent, it is an inevitable trend for new energy vehicles represented by pure electric-powered cars, two-wheelers, and three-wheelers to replace traditional fuel vehicles. Existing two-wheel electric vehicles generally use wheel hub motors, mid-mounted drives, and motor side-mounted structures.

[0003] The wheel hub motor structure is generally a low-speed motor directly connected to the wheel for driving. The low-speed motor has the problems of large size, heavy weight, and low efficiency (the efficiency is generally 60%-80%). In addition, the starting current is large, and it is easy to stall and generate a lot of heat. At the same time, due to poor handling performance, it is widely used in electric vehicles with a speed of less than 40km / h. If you want to reach a speed of more than 50km / h, you need to use a higher-cost low-speed motor, which has extremely poor handling and safety, and is prone to tire blowouts, etc., and is almost unusable.

[0004] The mid-mounted drive structure generally drives the wheel hub through a medium-to-low-speed motor plus a chain drive or a belt drive. The general reduction ratio is around 3.5-4.5, and there are problems such as complex structure, large size, and heavy weight. At the same time, the transmission efficiency is low, and there are many external parts that are easy to damage and need to be replaced regularly, resulting in high use and maintenance costs. In addition, due to the large size of the reduction mechanism, it occupies the installation space of the battery pack, resulting in a short cruising range.

[0005] The side-mounted drive structure is generally composed of a high-speed motor and a reduction mechanism, which is placed on one side of the vehicle's drive wheel. It is a multi-parallel axis drive reduction mechanism with complex structure, many parts, and heavy box weight. As a result, the wheel hub adopts a cup-shaped structure, which increases the weight and affects the handling. In addition, the high cost and unsightly appearance have affected its promotion and use.

[0006] Therefore, the inventor team has designed a new central drive electric drive system (please refer to Chinese invention patent application 201911413371.1 and Chinese utility model patent application 201922488415.9) to make up for the shortcomings of the three. It can not only ensure the balance and controllability of the whole vehicle, but also has extremely high mechanical efficiency, compact structure, decentralized and independent, good windward and transparent heat dissipation performance, light weight, and is suitable for front-wheel drive and rear-wheel drive of various types of two-wheeled vehicles, three-wheeled vehicles and four-wheeled vehicles, especially electric two-wheeled vehicles and electric three-wheeled vehicles.

[0007] However, during the design and testing process, the inventor team discovered that the centrally driven electric drive system designed in the past still had problems such as poor independence of the motor assembly, reduction gearbox and wheel hub structure, difficulty in disassembly and assembly, and overlapping connection and fixing methods of the components, resulting in a large number of components.

[0008] Therefore, the inventor team further optimized the structure and streamlined the number of parts to make it easier to assemble, disassemble and repair, and also reduce the volume and weight, lower manufacturing costs, and achieve "extreme simplicity" while further improving reliability and controllability, greatly enhancing product competitiveness, making it easier to promote and use, and making it more acceptable to the market. Summary of the invention

[0009] In order to solve the above technical problems, the present invention provides a central drive electric drive system.

[0010] The technical solution is as follows:

[0011] A central drive electric drive system includes a motor, a speed change mechanism and a wheel hub drive sleeve. The key points are: the speed change mechanism is installed on the motor shaft of the motor, the wheel hub drive sleeve is rotatably mounted on the motor shaft of the motor and is located between the speed change mechanism and the rotor of the motor, and the motor shaft transmits power to the wheel hub drive sleeve through the speed change mechanism.

[0012] With the above structure, the speed change mechanism and the wheel hub drive sleeve are directly installed on the extended motor shaft, which reduces the number of parts. Compared with the central drive electric drive system designed by the inventor's team in the past, it effectively solves the problems of poor independence of the motor assembly, reduction box and wheel hub structure, difficult disassembly and assembly, overlapping connection and fixing methods of parts, and large number of parts. It is not only easier to assemble, disassemble and repair, but also reduces the volume and weight, reduces manufacturing costs, and achieves "extreme simplicity". At the same time, it can further improve reliability and controllability, greatly enhance product competitiveness, and make it easier to promote and use, making it easier to accept in the market.

[0013] Preferably, the speed change mechanism comprises a primary driving gear fixedly sleeved on the motor shaft, an intermediate shaft parallel to the motor shaft, a primary driven gear fixedly sleeved on the intermediate shaft, and a secondary driven gear rotatably sleeved on the motor shaft, the primary driving gear meshes with the primary driven gear, the intermediate shaft has secondary driving teeth meshed with the secondary driven gear, and the secondary driven gear rotates synchronously with the wheel hub drive sleeve. With the above structure, the reduction transmission can be stably and reliably performed.

[0014] Preferably, the hub drive sleeve includes a drive gear sleeve portion and a drive spline portion formed on the outer peripheral surface of the drive gear sleeve portion, the secondary driven gear includes a secondary driven gear sleeve portion and a secondary driven gear toothed disc portion fixedly sleeved on the secondary driven gear sleeve portion, the secondary driven gear toothed disc portion meshes with the secondary active gear, the drive gear sleeve portion has a plurality of circumferentially distributed connecting grooves on an end surface close to one end of the secondary driven gear sleeve portion, the secondary driven gear sleeve portion has a plurality of connecting teeth adapted to the corresponding connecting grooves on an end surface close to one end of the drive gear sleeve portion, and each connecting tooth is respectively embedded in the corresponding connecting groove. With the above structure, the cooperation of the connecting teeth and the connecting grooves can not only ensure the stable transmission of the hub drive sleeve and the secondary driven gear, but also facilitate assembly.

[0015] Preferably, a combined wheel is sleeved on the hub drive sleeve, the combined wheel has a spline matching hole adapted to the hub drive sleeve at its center, and the wall of the spline matching hole has a driven spline part spline-matched with the driving spline part. With the above structure, power transmission can be carried out stably and reliably.

[0016] Preferably, the combined wheel comprises a hub bracket, a wheel hub and a tire which are coaxially arranged in sequence from the inside to the outside, the spline matching hole is located at the center of the hub bracket, the hub bracket is sleeved on the wheel hub drive sleeve, the wheel hub is a hollow structure and is detachably mounted on the hub bracket, and the tire is sleeved on the wheel hub. With the above structure, the motor and the speed change mechanism of the central drive electric drive system are respectively mounted on both sides of the hub bracket, and the wheel hub can be easily removed from the hub bracket. No matter whether it is disassembled or assembled, there is no need to remove the motor and the speed change mechanism, so that quick tire change can be achieved, which improves the convenience of maintenance of the central drive electric drive system.

[0017] Preferably, the outer ring of the wheel hub bracket has a wheel hub mounting ring, the inner ring of the wheel hub has a wheel hub mounting ring adapted to the wheel hub mounting ring, and the wheel hub mounting ring can be detachably fixed to the wheel hub mounting ring by a plurality of bolts. With the above structure, the wheel hub bracket and the wheel hub can be connected by bolts, which is stable and reliable, easy to disassemble and assemble, and low in cost.

[0018] Preferably, the wheel hub bracket has a plurality of first connection locking holes circumferentially distributed around the spline matching hole, and the wheel hub drive sleeve has a plurality of second connection locking holes that can be connected one by one with each first connection locking hole. When the wheel hub bracket is sleeved on the wheel hub drive sleeve, a plurality of locking pins can be inserted into the corresponding first connection locking holes and second connection locking holes. With the above structure, the relative position of the combined wheel and the wheel hub drive sleeve can be reliably locked, so as to avoid the combined wheel sliding left and right relative to the wheel hub drive sleeve or shaking of the combined wheel after long-term use.

[0019] As a preferred embodiment, the rotor, the primary driving gear, the secondary driven gear and both sides of the hub drive sleeve, both ends of the intermediate shaft and the outer end of the motor shaft are all provided with deep groove ball bearings. With the above structure, while ensuring the stability of each mechanism, the deep groove ball bearings are used as little as possible, which not only reduces the difficulty of assembly, but also further reduces the cost.

[0020] Preferably, oil seals are provided between the two deep groove ball bearings between the rotor and the hub drive sleeve and inside the deep groove ball bearings on both sides of the hub drive sleeve. The above structure can effectively prevent oil leakage.

[0021] Preferably, a half-moon key slot is provided on the motor shaft, the half-moon key slot is located between the primary driving gear and the deep groove ball bearing at the outer end of the motor shaft, and a detachable half-moon key is installed in the half-moon key slot; a motor locking nut is provided at one end of the motor shaft away from the speed change mechanism. With the above structure, the speed change mechanism can be reliably locked by the half-moon key, and the half-moon key is easy to disassemble and assemble, so that the speed change mechanism can be quickly disassembled and assembled; at the same time, by providing the motor locking nut, the main components of the motor (encoder, rotor, stator, etc.) can be quickly disassembled and assembled; through the above design, the main components of the motor and the speed change mechanism can be quickly disassembled, so as to facilitate the maintenance, inspection and replacement of the main components of the motor, the speed change mechanism and the wheel.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The centrally driven electric drive system adopting the above technical solution has a novel structure, is easy to implement, and has an ingenious design. The speed change mechanism and the wheel hub drive sleeve are directly installed on the extended motor shaft, reducing the number of parts. Compared with the centrally driven electric drive system designed by the inventor's team in the past, it effectively solves the problems of poor independence of the motor assembly, reduction box and wheel hub structure, difficulty in disassembly and assembly, overlapping connection and fixing methods of parts, and large number of parts. It is not only easier to assemble, disassemble and repair, but also can reduce volume and weight, reduce manufacturing costs, achieve "extreme simplicity", and further improve reliability and controllability, greatly enhance product competitiveness, and make it easier to promote and use, making it easier to accept in the market. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the coordination relationship of the main structures of the present invention;

[0025] Figure 2 It is a schematic diagram of the overall structure of the present invention;

[0026] Figure 3 It is a schematic diagram of the matching relationship between the secondary driven gear and the wheel hub drive sleeve;

[0027] Figure 4 It is a schematic diagram of the structure of the wheel hub drive sleeve;

[0028] Figure 5 is a structural schematic diagram of the secondary driven gear;

[0029] Figure 6 is a schematic diagram of the structure of a combined wheel;

[0030] Figure 7 It is a schematic diagram of the matching relationship between the combined wheel and the wheel hub drive sleeve;

[0031] Figure 8 A schematic diagram of one of the perspectives of the wheel hub bracket;

[0032] Fig. 9 This is a schematic diagram of the wheel hub bracket from another perspective;

[0033] Fig.10 This is a schematic diagram of one of the perspectives of the wheel hub;

[0034] Fig.11 This is a schematic diagram of another angle of view of the wheel hub. DETAILED DESCRIPTION

[0035] The present invention is further described below in conjunction with embodiments and drawings.

[0036] like Figure 1 As shown, a central drive electric drive system mainly includes a motor 1, a speed change mechanism and a wheel hub drive sleeve 2, wherein the speed change mechanism is mounted on the motor shaft 1a of the motor 1, and the wheel hub drive sleeve 2 is rotatably mounted on the motor shaft 1a of the motor 1 and is located between the speed change mechanism and the rotor 1b of the motor 1, and the motor shaft 1a transmits power to the wheel hub drive sleeve 2 through the speed change mechanism, and the wheel hub drive sleeve 2 outputs power.

[0037] The newly designed central drive structure combines the advantages of the hub motor structure, the mid-mounted drive structure and the side-mounted structure, and makes up for the shortcomings of the hub motor structure, the mid-mounted drive structure and the side-mounted structure. It is especially suitable for electric two-wheelers and electric three-wheelers.

[0038] See also Figure 1 and Figure 2In this embodiment, a combined wheel 7 is sleeved on the wheel hub drive sleeve 2. The combined wheel 7 includes a wheel hub bracket 7a, a wheel hub 7b and a tire 7c which are coaxially arranged in sequence from the inside to the outside. The wheel hub drive sleeve 2 drives the wheel hub bracket 7a to drive the combined wheel to rotate. The wheel hub 7b is a hollow structure, and the wheel hub 7b is detachably mounted on the wheel hub bracket 1a. The tire 7c is sleeved on the wheel hub 7b. The combined wheel 7 has a spline matching hole 71 adapted to the wheel hub drive sleeve 2 at the center position. The spline matching hole 71 has a driven spline part 72 spline-matched with the driving spline part 2b on the hole wall, that is, the wheel hub drive sleeve 2 and the combined wheel 7 are spline-matched, and power transmission can be reliably performed.

[0039] See also Figure 6-Figure 11 The outer ring of the wheel hub bracket 7a has a wheel hub mounting ring 7a1, and the inner ring of the wheel hub 7b has a wheel hub mounting ring 7b1 adapted to the wheel hub mounting ring 7a1. The wheel hub mounting ring 7b1 can be detachably fixed to the wheel hub mounting ring 7a1 by a plurality of bolts 7d. The motor 1 and the speed change mechanism of the central drive type electric drive system are respectively installed on both sides of the wheel hub bracket 7a. When the tire 7c needs to be replaced or repaired, only all the bolts 7d need to be removed (without disassembling the power system and the speed change mechanism), and the wheel hub 7b and the tire 7c can be removed together, which is exactly the same as the traditional method, so that the tire can be quickly changed, which improves the convenience of maintenance of the central drive type electric drive system.

[0040] See also Figure 8 and Fig. 9 The hub bracket 7a also includes a power input disc 7a2 coaxially arranged in the hub mounting ring 7a1. The hub mounting ring 7a1 and the power input disc 7a2 are connected by a plurality of bracket connecting ribs 7a3. The structure has high strength, stability and reliability, and is light in weight, which can achieve the purpose of weight reduction. The spline matching hole 71 is located at the center of the power input disc 7a2.

[0041] A concave cavity 7a22 is formed in one side of the power input disc 7a2, and a power input sleeve is arranged at the center of the concave cavity 7a22, and the shaft hole of the power input sleeve is the spline matching hole 71. The power input sleeve is basically hidden in the concave cavity 7a22, improving the overall appearance.

[0042] A plurality of reinforcing ribs 7a24 are arranged in the concave cavity 7a22, and each reinforcing rib 7a24 is distributed around the power input sleeve along the circumferential direction, and the two ends of each reinforcing rib 7a24 are respectively connected to the cavity wall of the concave cavity 7a22 and the outer wall of the power input sleeve, which can greatly improve the structural strength of the power input disc 7a2 and the power input sleeve. A circular flange 7a25 is formed on the disc surface of the power input disc 7a2 on the side opposite to the concave cavity 7a22, and a plurality of reinforcing protrusions 7a26 are arranged on the outer circumferential surface of the flange 7a25, which can ensure the structural strength of the flange 7a25.

[0043] See also Fig.10 and Fig.11 The wheel hub 7b also includes a tire mounting ring 7b2 coaxially arranged outside the wheel hub mounting ring 7b1. The tire mounting ring 7b2 and the wheel hub mounting ring 7b1 are connected by a plurality of wheel hub connecting ribs 7b3. The structure has high strength, stability and reliability, and is light in weight, which can achieve the purpose of weight reduction. In addition, a side surface of the wheel hub connecting rib 7b3 has a weight reduction groove 7b31, which achieves the weight reduction function under the premise of ensuring the structural strength. The side surface of the wheel hub mounting ring 7b1 on which the wheel hub mounting ring 7a1 is mounted has a mounting sink 7b11 adapted to the wheel hub mounting ring 7a1. The mounting sink 7b11 can not only position the wheel hub mounting ring 7a1 to improve the assembly efficiency, but also improve the reliability of the connection between the wheel hub bracket 7a and the wheel hub 7b.

[0044] Furthermore, in order to improve the reliability of the hub bracket 7a and the wheel hub 7b, the hub bracket 7a and the wheel hub 7b are integrally formed.

[0045] See also Figure 1 The speed change mechanism includes a primary driving gear 3 fixedly sleeved on the motor shaft 1a, an intermediate shaft 4 parallel to the motor shaft 1a, a primary driven gear 5 fixedly sleeved on the intermediate shaft 4, and a secondary driven gear 6 rotatably sleeved on the motor shaft 1a, the primary driving gear 3 is meshed with the primary driven gear 5, the intermediate shaft 4 has a secondary driving tooth 4a meshed with the secondary driven gear 6, and the secondary driven gear 6 rotates synchronously with the wheel hub drive sleeve 2.

[0046] The motor shaft 1a drives the primary driving gear 3, the primary driving gear 3 drives the primary driven gear 5, the primary driven gear 5 drives the intermediate shaft 4, the secondary driving gear 4a of the intermediate shaft 4 drives the secondary driven gear 6, the secondary driven gear 6 drives the wheel hub drive sleeve 2, and the wheel hub drive sleeve 2 drives the combined wheel 7.

[0047] For further information, see Figure 2 A transmission mechanism case 11 is wrapped outside the transmission mechanism, which can protect the transmission mechanism and make the whole more beautiful.

[0048] See also Figure 3-Figure 5 The hub drive sleeve 2 includes a drive gear sleeve portion 2a and a drive spline portion 2b formed on the outer peripheral surface of the drive gear sleeve portion 2a. The secondary driven gear 6 includes a secondary driven gear sleeve portion 6a and a secondary driven gear toothed disc portion 6b fixedly sleeved on the secondary driven gear sleeve portion 6a. The secondary driven gear toothed disc portion 6b meshes with the secondary active gear 4a. The drive gear sleeve portion 2a has a plurality of circumferentially distributed connecting grooves 2a1 on the end surface close to the secondary driven gear sleeve portion 6a. The secondary driven gear sleeve portion 6a has a plurality of connecting teeth 6a1 adapted to the corresponding connecting grooves 2a1 on the end surface close to the drive gear sleeve portion 2a. Each connecting tooth 6a1 is respectively embedded in the corresponding connecting groove 2a1. Through the cooperation of the connecting teeth 6a1 and the connecting grooves 2a1, the hub drive sleeve 2 and the secondary driven gear 6 can be stably transmitted and easily assembled.

[0049] See also Figure 7 The wheel hub bracket 7a has a plurality of first connection locking holes 7a4 distributed circumferentially around the spline matching hole 71, and the wheel hub drive sleeve 2 has a plurality of second connection locking holes 2c that can be connected one by one with each first connection locking hole 7a4. When the wheel hub bracket 7a is sleeved on the wheel hub drive sleeve 2, a plurality of locking pins 13 can be inserted into the corresponding first connection locking holes 7a4 and second connection locking holes 2c. With the above structure, the relative position of the combined wheel 7 and the wheel hub drive sleeve 2 can be reliably locked to prevent the combined wheel 7 from sliding left and right relative to the wheel hub drive sleeve 2 or shaking of the combined wheel 7 after long-term use. Furthermore, after the locking pin 13 is inserted into the corresponding first connection locking hole 7a4 and the second connection locking hole 2c, it can be fixed by gluing or the like.

[0050] See also Figure 1 The rotor 1b, the primary driving gear 3, the secondary driven gear 6, both sides of the hub drive sleeve 2, both ends of the intermediate shaft 4 and the outer end of the motor shaft 1a are all provided with deep groove ball bearings 8. While ensuring the stability of each mechanism, the deep groove ball bearings 8 are used as little as possible, which not only reduces the difficulty of assembly, but also further reduces the cost.

[0051] Oil seals 9 are provided between the two deep groove ball bearings 8 between the rotor 1b and the hub drive sleeve 2 and inside the deep groove ball bearings 8 on both sides of the hub drive sleeve 2, which can effectively prevent oil leakage.

[0052] The motor shaft 1a is provided with a half-moon key slot 1a1, which is located between the primary driving gear 3 and the deep groove ball bearing 8 at the outer end of the motor shaft 1a. A detachable half-moon key 10 is installed in the half-moon key slot 1a1, and the speed change mechanism can be reliably locked by the half-moon key 10. Moreover, the half-moon key 10 is easy to disassemble and assemble, so that the speed change mechanism can be quickly disassembled and assembled. The motor shaft 1a is provided with a motor locking nut 12 at one end away from the speed change mechanism. Unscrewing the motor locking nut 12 can conveniently disassemble and assemble the encoder 1c, the rotor 1b and the stator 1d and other components. Through the above design, the main components and the speed change mechanism of the motor 1 can be quickly disassembled, so as to facilitate the maintenance, overhaul and replacement of the main components of the motor, the speed change mechanism and the combined wheel.

[0053] Finally, it should be noted that the above description is only a preferred embodiment of the present invention. Under the guidance of the present invention, ordinary technicians in this field can make various similar expressions without violating the purpose and claims of the present invention, and such changes all fall within the scope of protection of the present invention.

Claims

1. A central drive electric drive system, characterized in that: It includes a motor, a speed change mechanism and a wheel hub drive sleeve, wherein the speed change mechanism is mounted on the motor shaft of the motor, the wheel hub drive sleeve is rotatably mounted on the motor shaft of the motor and is located between the speed change mechanism and the rotor of the motor, the motor shaft transmits power to the wheel hub drive sleeve through the speed change mechanism, and the wheel hub drive sleeve outputs power; A combined wheel is sleeved on the wheel hub drive sleeve, and the combined wheel includes a wheel hub bracket, a wheel hub and a tire which are coaxially arranged in sequence from the inside to the outside; the wheel hub drive sleeve drives the wheel hub bracket to drive the combined wheel to rotate; The wheel hub is a hollow structure and can be detachably mounted on the wheel hub bracket; the tire sleeve is mounted on the wheel hub; a spline matching hole adapted to the wheel hub drive sleeve is provided at the center of the combined wheel, and a driven spline portion spline-matched with the driving spline portion is provided on the hole wall of the spline matching hole; The outer ring of the wheel hub bracket has a wheel hub mounting ring, the inner ring of the wheel hub has a wheel hub mounting ring adapted to the wheel hub mounting ring, and the wheel hub mounting ring can be detachably fixed to the wheel hub mounting ring by a plurality of bolts; the motor and the speed change mechanism of the central drive type electric drive system are respectively mounted on both sides of the wheel hub bracket; The wheel hub bracket also includes a power input disc coaxially arranged in the wheel hub mounting ring, and the wheel hub mounting ring and the power input disc are connected by a plurality of bracket connecting ribs; the spline matching hole is located at the center of the power input disc; A concave cavity is formed in one side of the power input disc, a power input sleeve is arranged at the center of the concave cavity, and the shaft hole of the power input sleeve is the spline matching hole; the power input sleeve is basically hidden in the concave cavity; A plurality of reinforcing ribs are arranged in the concave cavity, each of which is distributed around the power input sleeve along the circumferential direction, and the two ends of each reinforcing rib are respectively connected to the cavity wall of the concave cavity and the outer wall of the power input sleeve; a circular annular flange is formed on the disk surface of the power input disk opposite to the concave cavity, and a plurality of reinforcing protrusions are arranged on the outer circumferential surface of the flange; The wheel hub also includes a tire mounting ring coaxially arranged outside the wheel hub mounting ring, and the tire mounting ring and the wheel hub mounting ring are connected by a plurality of wheel hub connecting ribs; and a weight-reducing groove is provided on one side surface of the wheel hub connecting rib; and a mounting sink adapted to the wheel hub mounting ring is provided on one side surface of the wheel hub mounting ring for mounting the wheel hub mounting ring; The wheel hub bracket and the wheel hub are integrally formed; The speed change mechanism comprises a primary driving gear fixedly sleeved on the motor shaft, an intermediate shaft parallel to the motor shaft, a primary driven gear fixedly sleeved on the intermediate shaft, and a secondary driven gear rotatably sleeved on the motor shaft, the primary driving gear meshes with the primary driven gear, the intermediate shaft has a secondary driving tooth meshing with the secondary driven gear, and the secondary driven gear rotates synchronously with the wheel hub drive sleeve; The motor shaft drives a primary driving gear, the primary driving gear drives a primary driven gear, the primary driven gear drives an intermediate shaft, the secondary driving gear of the intermediate shaft drives a secondary driven gear, the secondary driven gear drives a wheel hub drive sleeve, and the wheel hub drive sleeve drives the combined wheel; A speed change mechanism housing is enclosed outside the speed change mechanism; The hub drive sleeve comprises a driving gear shaft sleeve portion and a driving spline portion formed on the outer peripheral surface of the driving gear shaft sleeve portion, the secondary driven gear comprises a secondary driven gear shaft sleeve portion and a secondary driven gear toothed disc portion fixedly sleeved on the secondary driven gear shaft sleeve portion, the secondary driven gear toothed disc portion meshes with the secondary active teeth, the driving gear shaft sleeve portion is provided with a plurality of circumferentially distributed connecting grooves on an end surface close to one end of the secondary driven gear shaft sleeve portion, the secondary driven gear shaft sleeve portion is provided with a plurality of connecting teeth adapted to the corresponding connecting grooves on an end surface close to one end of the driving gear shaft sleeve portion, and each connecting tooth is respectively embedded in the corresponding connecting groove; through the cooperation of the connecting teeth and the connecting grooves; The wheel hub bracket is provided with a plurality of first connection locking holes distributed circumferentially around the spline matching hole, and the wheel hub drive sleeve is provided with a plurality of second connection locking holes which can be connected one by one with the first connection locking holes. When the wheel hub bracket is sleeved on the wheel hub drive sleeve, a plurality of locking pins can be inserted into the corresponding first connection locking holes and the second connection locking holes; the locking pins are inserted into the corresponding first connection locking holes and the second connection locking holes and fixed by gluing; The rotor, the primary driving gear, the secondary driven gear and both sides of the hub drive sleeve, the two ends of the intermediate shaft and the outer end of the motor shaft are all provided with deep groove ball bearings; Oil seals are provided between the two deep groove ball bearings between the rotor and the wheel hub drive sleeve and inside the deep groove ball bearings on both sides of the wheel hub drive sleeve; The motor shaft is provided with a half-moon key slot, which is located between the primary driving gear and the deep groove ball bearing at the outer end of the motor shaft, and a detachable half-moon key is installed in the half-moon key slot; the motor shaft is provided with a motor locking nut at one end away from the speed change mechanism.

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