阅读说明：本技术 纯电动汽车两挡变速器 (Two-gear transmission of pure electric vehicle ) 是由 雷贞贞 关卫卫 陈峥 刘永刚 李�杰 袁理 吴桂华 于 2019-09-12 设计创作，主要内容包括：一种纯电动汽车两挡变速器,包括箱体、输入轴、输出轴,输入轴上滑动配合高速挡主动齿轮、低速挡主动齿轮,输出轴上固定高速挡从动齿轮、低速挡从动齿轮,高速挡主动齿轮、低速挡主动齿轮之间设置两个摩擦离合器,摩擦离合器的从动摩擦盘均空套在输入轴上,分别与高速挡主动齿轮、低速挡主动齿轮周向固定连接,两个摩擦离合器的主动摩擦盘分别固定连接压盘,两个压盘均周向定位可轴向移动的滑动配合在输入轴上,各压盘分别通过压杆固定连接推盘,两个推盘之间设置换挡凸轮,换挡凸轮轴向与输入轴轴向垂直,换挡凸轮的凸轮轴通过齿轮减速装置与安装在箱体上的换挡驱动电机连接,一回位弹簧位于两个推盘之间空套在输入轴上且与两推盘连接固定。(A two-gear transmission of a pure electric vehicle comprises a box body, an input shaft and an output shaft, wherein a high-speed gear driving gear and a low-speed gear driving gear are in sliding fit on the input shaft, a high-speed gear driven gear and a low-speed gear driven gear are fixed on the output shaft, two friction clutches are arranged between the high-speed gear driving gear and the low-speed gear driving gear, driven friction discs of the friction clutches are sleeved on the input shaft in a non-slip mode and are respectively and fixedly connected with the high-speed gear driving gear and the low-speed gear driving gear in the circumferential direction, driving friction discs of the two friction clutches are respectively and fixedly connected with pressure discs, the two pressure discs are circumferentially positioned and axially matched on the input shaft in a sliding fit mode, each pressure disc is respectively and fixedly connected with a push disc through a pressure rod, a gear shifting cam is arranged between the two push discs, the axial direction, a return spring is positioned between the two push disks, is sleeved on the input shaft in an empty way and is fixedly connected with the two push disks.)

1. The utility model provides a pure electric vehicles two keeps off derailleur, includes box, input shaft, output shaft, its characterized in that: the input shaft and the output shaft are parallel and are respectively supported on the side wall of the box body through bearings, the input shaft is respectively axially limited and matched with a high-speed gear driving gear and a low-speed gear driving gear in a sliding manner, the output shaft is fixedly connected with a high-speed gear driven gear and a low-speed gear driven gear, the high-speed gear driven gear is meshed with the high-speed gear driving gear, the low-speed gear driven gear is meshed with the low-speed gear driving gear, two friction clutches are arranged between the high-speed gear driving gear and the low-speed gear driving gear, driven friction discs of the two friction clutches are sleeved on the input shaft in an empty manner, the high-speed gear driving gear is circumferentially and fixedly connected with a driven friction disc of one friction clutch through a connecting seat, the low-speed gear driving gear is circumferentially and fixedly connected with a driven friction disc of, but the equal circumference of pressure disk of two friction clutch fixes a position axial displacement's sliding fit on the input shaft, and each friction clutch's pressure disk is respectively through depression bar fixed connection push disk, and push disk empty sleeve sets up the cam of shifting between two friction clutch's the push disk on the input shaft, the cam of shifting is located the radial side of input shaft, and the cam axial of shifting is perpendicular with the input shaft axial, two axial end faces and the cam contact of shifting of push disk, the camshaft of the cam of shifting passes through gear reduction unit and is connected with the driving motor of shifting of installing on the box, and a return spring is located between two push disks empty sleeve and is connected fixedly on the input shaft and with two push disks.

2. The two-speed transmission of the pure electric vehicle according to claim 1, characterized in that: the opposite ends of the two push disks are respectively provided with four fixing hooks which are uniformly distributed on the edges of the shaft holes of the push disks, the end parts of the return springs are restrained and fixed by the four fixing hooks, the two opposite ends of the two push disks are fixedly connected with two pressure rods, the two pressure rods are symmetrically arranged, and the two ends of each pressure rod are fixedly connected with the support arranged on the pressure plate.

3. The two-speed transmission of the pure electric vehicle according to claim 1 or 2, characterized in that: the pressure bar is an elastic pressure bar with an arch trapezoid structure, the arch crown of the elastic pressure bar and the push disc are fixedly riveted through pins, and the extending ends of the inclined arms on the two sides of the elastic pressure bar are fixedly connected with the support on the pressure disc through pin shafts.

4. The two-speed transmission of the pure electric vehicle according to claim 1, characterized in that: the input shaft is the step shaft, this step shaft middle part is big footpath section, this step shaft both ends are the path section, be the path section between big footpath section and the path section, the high-speed fender driving gear, the low-speed fender driving gear respectively sliding fit on the path section at both ends and by path section shoulder axial spacing, two friction clutch are located the path section respectively, each friction clutch's push away the dish by big footpath section shoulder axial spacing, but each friction clutch's pressure disk circumferential location axial displacement's sliding fit is on the path section.

5. The two-speed transmission of the pure electric vehicle according to claim 1, characterized in that: the driving friction disc and the pressure plate are fixedly connected through a plurality of bolts, the driven friction disc and the connecting seat are fixedly connected through a plurality of bolts, and the connecting seat and the axial end face of the corresponding driving gear are fixedly connected through a plurality of screws to form circumferential fixation.

6. The two-speed transmission of the pure electric vehicle according to claim 1, characterized in that: the gear shifting mechanism is characterized in that the cam shaft is supported on a supporting frame arranged in the box body, a gear shifting cam is fixedly arranged at one end of the cam shaft, the other end of the cam shaft is connected with an output shaft of the gear speed reducing device through a first coupler, and an input shaft of the gear speed reducing device is connected with a rotating shaft of the gear shifting driving motor through a second coupler.

7. The two-speed transmission of the pure electric vehicle according to claim 6, characterized in that: one end of the supporting frame supports the cam shaft through a bearing, and the other end of the supporting frame is fixed with the upper cover or the bottom shell of the box body.

8. The two-speed transmission of the pure electric vehicle according to claim 1, characterized in that: two corresponding gear shifting cams are arranged between the two push discs, the two gear shifting cams are symmetrically positioned on two radial sides of the input shaft, and cam shafts of the gear shifting cams are respectively connected with a gear shifting driving motor arranged on the side through gear reduction devices arranged on the side.

9. The two-speed transmission of the pure electric vehicle according to claim 1, characterized in that: the gear shifting driving motor adopts a bidirectional stepping motor, and the gear reduction device adopts a bevel gear rotating mechanism.

10. The two-speed transmission of the pure electric vehicle according to claim 1, characterized in that: the gear shifting cam is a disc cam.

Technical Field

The invention relates to the field of automobile transmissions, in particular to a two-gear transmission of a pure electric automobile.

Background

The main reducer of the transmission system of the mainstream automobile type of the traditional pure electric automobile generally adopts a single-stage transmission, the transmission with the structure can only provide a fixed reduction ratio, the reduction ratio cannot be adjusted by changing gears aiming at various running states of the whole automobile in use, the output rotating speed and the output torque of a traction motor are difficult to be adjusted adaptively, and the traction motor usually stays in a high-load running state for a long time due to the fact that the traction motor is usually in a working low-efficiency area, so that the problems of reduction of driving mileage and obvious insufficient cruising ability caused by increase of battery energy loss are caused. And because the work load fluctuation of the power system is large, the requirement on the quality of the traction motor is high, the development difficulty of the traction motor is large, and the manufacturing cost is high. Therefore, in the field of pure electric vehicles, how to improve the cruising ability of the electric vehicles and how to reduce the development difficulty and the manufacturing cost of the traction motor has been a difficult problem which is difficult to solve in the field for a long time.

Disclosure of Invention

The invention aims to provide a two-gear transmission of a pure electric vehicle, aiming at the defects of insufficient cruising ability, high development difficulty of a power system and the like caused by the fact that the existing main stream vehicle type transmission system of the pure electric vehicle is only provided with a main speed reducer. The two-gear transmission is mounted, and the friction clutches of the two gears are directly driven by the gear shifting cam to be respectively engaged or disengaged to realize gear shifting. The reduction ratio can be adjusted through shifting, the energy loss of the battery is reduced, the cruising ability is increased, the complexity of the structure of the transmission and the requirements of the manufacturing process can be reduced, and the development difficulty and the manufacturing cost of the traction motor can be reduced.

The purpose of the invention is realized as follows: a two-gear transmission of a pure electric vehicle comprises a box body, an input shaft and an output shaft, wherein the input shaft and the output shaft are parallel and are respectively supported on the side wall of the box body through bearings, the input shaft is respectively axially and limitedly matched with a high-gear driving gear and a low-gear driving gear in a sliding manner, the output shaft is fixedly connected with a high-gear driven gear and a low-gear driven gear, the high-gear driven gear is meshed with the high-gear driving gear, the low-gear driven gear is meshed with the low-gear driving gear, two friction clutches are arranged between the high-gear driving gear and the low-gear driving gear, driven friction discs of the two friction clutches are sleeved on the input shaft in an empty manner, the high-gear driving gear is circumferentially and fixedly connected with a driven friction disc of one friction clutch through a connecting seat, the low-gear driving gear is circumferentially and, the driving friction discs of the two friction clutches are fixedly connected with pressure plates respectively, the pressure plates of the two friction clutches are circumferentially positioned and can axially move in a sliding fit mode on the input shaft, the pressure plates of the friction clutches are fixedly connected with push plates through pressure rods respectively, the push plates are sleeved on the input shaft in an empty mode, a gear shifting cam is arranged between the push plates of the two friction clutches and is located on the radial side of the input shaft, the axial direction of the gear shifting cam is perpendicular to the axial direction of the input shaft, the axial end faces of the two push plates are in contact with the gear shifting cam, a cam shaft of the gear shifting cam is connected with a gear shifting driving motor installed on a box body through a gear reduction device, and a return spring is located between the two push plates and is sleeved on the input shaft in an empty mode and.

The opposite ends of the two push disks are respectively provided with four fixing hooks which are uniformly distributed on the edges of the shaft holes of the push disks, the end parts of the return springs are restrained and fixed by the four fixing hooks, the two opposite ends of the two push disks are fixedly connected with two pressure rods, the two pressure rods are symmetrically arranged, and the two ends of each pressure rod are fixedly connected with the support arranged on the pressure plate.

The pressure bar is an elastic pressure bar with an arch trapezoid structure, the arch crown of the elastic pressure bar and the push disc are fixedly riveted through pins, and the extending ends of the inclined arms on the two sides of the elastic pressure bar are fixedly connected with the support on the pressure disc through pin shafts.

The input shaft is the step shaft, this step shaft middle part is big footpath section, this step shaft both ends are the path section, be the path section between big footpath section and the path section, the high-speed fender driving gear, the low-speed fender driving gear respectively sliding fit on the path section at both ends and by path section shoulder axial spacing, two friction clutch are located the path section respectively, each friction clutch's push away the dish by big footpath section shoulder axial spacing, but each friction clutch's pressure disk circumferential location axial displacement's sliding fit is on the path section.

The driving friction disc and the pressure plate are fixedly connected through a plurality of bolts, the driven friction disc and the connecting seat are fixedly connected through a plurality of bolts, and the connecting seat and the axial end face of the corresponding driving gear are fixedly connected through a plurality of screws to form circumferential fixation.

The gear shifting mechanism is characterized in that the cam shaft is supported on a supporting frame arranged in the box body, a gear shifting cam is fixedly arranged at one end of the cam shaft, the other end of the cam shaft is connected with an output shaft of the gear speed reducing device through a first coupler, and an input shaft of the gear speed reducing device is connected with a rotating shaft of the gear shifting driving motor through a second coupler.

One end of the supporting frame supports the cam shaft through a bearing, and the other end of the supporting frame is fixed with the upper cover or the bottom shell of the box body.

Two corresponding gear shifting cams are arranged between the two push discs, the two gear shifting cams are symmetrically positioned on two radial sides of the input shaft, and cam shafts of the gear shifting cams are respectively connected with a gear shifting driving motor arranged on the side through gear reduction devices arranged on the side.

The gear shifting driving motor adopts a bidirectional stepping motor, and the gear reduction device adopts a bevel gear rotating mechanism.

The gear shifting cam is a disc cam.

Adopt the pure electric vehicles two to keep off derailleur of above-mentioned scheme, through set up two friction clutch between the spacing sliding fit's of axial high-speed gear driving gear, the low-speed gear driving gear respectively on the input shaft, two friction clutch's driven friction disk is homoenergetic to overlap on the input shaft. The high-speed gear driving gear is fixedly connected with a driven friction disc of one friction clutch in the circumferential direction through the connecting seat, and the low-speed gear driving gear is fixedly connected with a driven friction disc of the other friction clutch in the circumferential direction through the connecting seat, so that the driven friction disc can drive the driving gear to rotate. The driving friction discs of the two friction clutches are respectively fixedly connected with pressure plates, and the pressure plates of the two friction clutches are circumferentially positioned and axially moved and are in sliding fit on the input shaft, so that the rotating torque of the input shaft can be transmitted to the driving friction discs through the pressure plates. The pressure plates of the friction clutches are fixedly connected with push plates through pressure rods respectively, the push plates are sleeved on the input shaft in an empty mode, a gear shifting cam is arranged between the push plates of the two friction clutches and located on the radial side of the input shaft, the axial direction of the gear shifting cam is perpendicular to the axial direction of the input shaft, and the gear shifting cam is in contact with the axial end faces of the two push plates. The camshaft of the gear shifting cam is connected with a gear shifting driving motor installed on the box body through a gear reduction device, and a return spring is positioned between the two push discs, is sleeved on the input shaft and is fixedly connected with the two push discs. Under the drive of the gear shifting drive motor, the gear shifting cam is rotated clockwise or anticlockwise to push a driving friction disc of one friction clutch to be jointed with a driven friction disc, so that the torque of an input shaft is transmitted to a high-speed gear driving gear or a low-speed gear driving gear through the friction clutch, the power switching of the high-speed gear or the low-speed gear is completed, and the friction clutch is kept in a jointed state to transmit power under the continuous drive of the gear shifting drive motor. When the gear is switched to another gear, the gear-shifting driving motor drives the gear-shifting cam to rotate, the thrust on the friction clutch in the working state is released, the push disc drives the driving friction disc and the driven friction disc to separate through the pressure disc under the action of the return spring, the power transmission of the friction clutch is interrupted, and the gear-shifting cam drives the driving friction disc and the driven friction disc of another friction clutch to be connected under the driving of the gear-shifting driving motor, so that the gear switching is completed. The gear shifting structure adopting the cam mechanism and the two friction clutches for matching utilizes friction force to transmit gear shifting power, is completely different from the traditional transmission adopting a mode that a shifting fork shifts a gear shifting synchronizer to realize gear shifting, and solves the problem that the traditional transmission is damaged due to severe gear beating, gear burning and the like in the gear shifting process; meanwhile, the problem of starting shake of the traction motor of the electric automobile caused by overlarge rotating speed output range can be solved.

The two pushing plates are provided with four fixing hooks at opposite ends respectively, the end parts of the return springs are restrained and fixed by the four fixing hooks, the return springs which are sleeved on the input shaft and are positioned between the two pushing plates can be conveniently installed and fixedly connected, the pushing plates can return after the pushing force is released by the action of the return springs, the driving friction disc and the driven friction disc of the friction clutch are separated, and power transmission is interrupted. Two pressure bars are fixedly connected with the opposite ends of the two push plates, the two pressure bars are symmetrically arranged, and the two ends of each pressure bar are fixedly connected with the support arranged on the pressure plate. The two pressing rods which are symmetrically arranged are adopted, so that the balanced thrust of the push plate can be transmitted to the pressure plate, the deviation cannot occur when the driving friction disc and the driven friction disc which are fixedly connected on the pressure plate are jointed, the power transmission stability of the friction clutch can be ensured, the friction plate abrasion aggravation on the driving friction disc and the driven friction disc can be prevented, and the service life of the friction plate can be prolonged.

The pressure bar is an elastic pressure bar with an arch trapezoid structure, the arch crown of the elastic pressure bar and the push disc are fixedly riveted through pins, and the extending ends of the inclined arms on the two sides of the elastic pressure bar are fixedly connected with the support on the pressure disc through pin shafts. The compression bar adopts an elastic compression bar with an arch trapezoid structure, belongs to two concentrated load structures, can ensure the balance of thrust and is convenient for the connection and fixation of the compression bar and the pressure plate.

Two corresponding gear shifting cams are arranged between the two push discs, the two gear shifting cams are symmetrically positioned on two radial sides of the input shaft, and cam shafts of the gear shifting cams are respectively connected with a gear shifting driving motor arranged on the side through gear reduction devices arranged on the side. Two gear shifting cams and two gear shifting driving motors are arranged to form two sets of gear shifting driving mechanisms, so that the two sets of gear shifting driving mechanisms can drive one friction clutch to realize gear shifting by the two sets of gear shifting driving mechanisms under the control of a motor controller, and the two cams apply synchronous thrust to a push disc to ensure more balanced thrust; the two sets of gear shifting driving mechanisms can be used for driving the gear shifting of a high gear independently and driving the gear shifting of a low gear independently.

This pure electric vehicles two keeps off derailleur and traditional two separation and reunion derailleurs compare, owing to adopt the friction clutch transmission or the interrupted power of the cam direct drive high-speed gear of shifting gears or low-speed gear, power transmission and conversion are more smooth and easy. And the wear defect of the friction plate can be compensated through the cam push stroke profile, the wear in friction transmission is compensated, the friction clutch is kept in a compression state to transmit torque when being engaged under the thrust action of the gear shifting cam, and the working reliability of the transmission is improved. Compared with the traditional double-clutch transmission, the structure of the two-gear transmission of the pure electric vehicle is simplified in internal structure, the whole weight is reduced, the structural complexity and the manufacturing process requirement of the transmission can be reduced, the development cost and the manufacturing cost of the two-gear transmission of the pure electric vehicle are reduced, the two-gear transmission of the pure electric vehicle can be used for models of the pure electric vehicles with different prices, and the two-gear transmission of the pure electric vehicle has wide popularization value.

The invention is further described below with reference to the accompanying drawings and specific examples.

Drawings

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is a sectional view taken along line A-A of FIG. 1;

FIG. 3 is a schematic structural view of the friction clutch of the present invention;

FIG. 4 is a schematic view of the shift cam configuration of the present invention;

FIG. 5 is a schematic view of a pressure plate configuration of the friction clutch of the present invention;

fig. 6 is a schematic view of fig. 1 in the direction B.

Detailed Description

Referring to fig. 1 to 6, an embodiment of a two-gear transmission of a pure electric vehicle according to the present invention includes a case 1, an input shaft 2, and an output shaft 3. The box body 1 comprises peripheral side walls, an upper cover 14 and a bottom shell 26, the upper cover 14 and the bottom shell 26 are fixedly connected with the peripheral side walls through screws, and sealing gaskets are arranged at joint seams of connecting end faces of the upper cover and the bottom shell. The input shaft 2 and the output shaft 3 are parallel and are respectively supported on the side walls of the front end and the rear end of the box body 1 through bearings, the front end of the input shaft 2 extends out of the box body 1 and is used for connecting a traction motor, and the rear end of the output shaft 3 extends out of the box body 1 and is used for connecting a transmission shaft; the bearing mounting holes on the box body 1 are all covered by bearing end covers 4, wherein gaps between the extending ends of the input shaft 2 and the output shaft 3 and the bearing end covers 4 are sealed by oil seals 5. The input shaft 2 is axially limited and slidably matched with a high-speed driving gear 9 and a low-speed driving gear 22. A high-speed driven gear 8 and a low-speed driven gear 28 are fixedly connected to the output shaft 3, and the high-speed driven gear 8 and the low-speed driven gear 28 are respectively and circumferentially and fixedly connected to the output shaft 3 through keys 25. The high-speed driven gear 8 meshes with the high-speed driving gear 9, and the low-speed driven gear 28 meshes with the low-speed driving gear 22, and these driving gears and driven gears are located in the case 1. Two friction clutches are arranged between the high-speed driving gear 9 and the low-speed driving gear 22, each friction clutch comprises a driving friction disc 17 and a driven friction disc 11, and friction plates on the driving friction disc 17 are opposite to friction plates on the driven friction discs 11. The driven friction discs 11 of the two friction clutches are sleeved on the input shaft 2 in an empty mode, the high-speed driving gear 9 is circumferentially and fixedly connected with the driven friction disc 11 of one friction clutch through a connecting seat 12, and the low-speed driving gear 22 is circumferentially and fixedly connected with the driven friction disc of the other friction clutch through a connecting seat. Each driven friction disc 11 and the connecting seat 12 of the present embodiment are fixedly connected by four bolts, and each connecting seat 12 and the axial end surface of the corresponding driving gear are fixedly connected by four screws to form circumferential fixation. Of course, the driven friction disk 11 and the connecting seat 12, and the connecting seat 12 and the corresponding driving gear may also be respectively fixed and connected by two or three screws. The driving friction discs 17 of the two friction clutches are respectively and fixedly connected with the pressure plate 18, each driving friction disc 17 is fixedly connected with the pressure plate 18 through a plurality of bolts, and the driving friction discs 17 are tightly connected with the pressure plate through four uniformly distributed bolts in the embodiment. The pressure plates 18 of the two friction clutches are circumferentially positioned and axially moved in a sliding fit mode on the input shaft 2, the circumferentially positioned and axially moved sliding fit mode can adopt a guide key 6 or spline fit mode, the guide key 6 is matched in the embodiment, a circumferential positioning groove 18-2 is arranged in a shaft hole 18-1 of the pressure plate 18, the guide key 6 is fixedly connected to the input shaft 2 through a screw, and the circumferential positioning groove 18-2 of the pressure plate 18 and the guide key 6 are in sliding fit to form a circumferentially positioned and axially moved state. The pressure plate 18 of each friction clutch is fixedly connected with the push plate 16 through a pressure rod 19, the opposite ends of the two push plates 16 are fixedly connected with two pressure rods 19, the two pressure rods 19 are symmetrically arranged, and the two ends of each pressure rod 19 are fixedly connected with a support 18-3 arranged on the pressure plate 18. The support 18-3 of this embodiment is four protrusions integrally formed on the pressure plate 18, the two pressure rods 19 are elastic pressure rods having an arch-shaped structure, the arch tops of the elastic pressure rods are riveted and fixed with the push plate 16 through pins 23, and the extending ends of the inclined arms at two sides of the elastic pressure rods are connected and fixed with the support 18-3 symmetrically arranged on the pressure plate 18 through pins 15. The push discs 16 are sleeved on the input shaft 2 in an empty mode, a shifting cam 20 is arranged between the push discs 16 of the two friction clutches, the shifting cam 20 is located on the radial side of the input shaft 2, the axial direction of the shifting cam 20 is perpendicular to the axial direction of the input shaft, the shifting cam 20 is a disc-shaped cam, and the axial end faces of the two push discs 16 are in contact with the shifting cam 20. The camshaft 20a of the shift cam 20 is connected to a shift drive motor 27 mounted on the housing 1 via a gear reduction 31. The shift driving motor 27 of this embodiment is a bi-directional stepping motor, and the controller of the bi-directional stepping motor can control the rotation angle of the shift cam 20 to press the driving friction disk 17 and the driven friction disk 11 of the friction clutch to transmit power. The gear reduction unit 31 employs a bevel gear rotating mechanism. The gear shifting driving motor 27 and the gear reduction device 31 of the embodiment are both fixedly installed on the outer wall of the box body 1 and located on the left side or the right side wall of the box body 1, and an output shaft of the gear reduction device 31 extends into the box body 1. The camshaft 20a is supported on a support frame 13 arranged in the box body 1, one end of the support frame 13 supports the camshaft 20a through a bearing, and the other end is fixed with the upper cover 14 or the bottom shell 26 of the box body 1. The supporting frame 13 of the present embodiment is fixedly connected to the upper cover 14 of the box body 1 by screws, and of course, the supporting frame 13 may also be welded to or integrally formed with the upper cover 14. A shift cam 20 is fixedly arranged at one end of the cam shaft 20a, the shift cam 20 and the cam shaft 20a are circumferentially fixed through a tight key 7, or the shift cam 20 and the cam shaft 20a are of an integral structure; the other end of the camshaft 20a is connected to an output shaft of a gear reduction unit 31 via a first coupling 29, and an input shaft of the gear reduction unit 31 is connected to a rotary shaft of the shift drive motor 27 via a second coupling 30. A return spring 21 is positioned between the two push disks 16 and is sleeved on the input shaft 2 in an empty way and is fixedly connected with the two push disks 16, the opposite ends of the two push disks 16 are respectively provided with four fixed hooks 24, the four fixed hooks 24 are uniformly distributed at the edge of the shaft hole of the push disk 16 and are integrally formed with the push disk 16, and the end part of the return spring 21 is restrained and fixed by the four fixed hooks 24.

The input shaft 2 of this embodiment is the step shaft, and this step shaft middle part is big footpath section, and this step shaft both ends are the path section, are the path section between big footpath section and the path section. The high-speed gear driving gear 9 and the low-speed gear driving gear 22 are respectively in sliding fit with the small-diameter sections at the two ends and are axially limited by small-diameter section shaft shoulders, and bearing bushes 10 are arranged between the high-speed gear driving gear 9, the low-speed gear driving gear 22 and the small-diameter section of the input shaft 2 and used for reducing friction. The two friction clutches are respectively positioned on the middle diameter section, the push disc 16 of each friction clutch is axially limited by the shaft shoulder of the large diameter section, and the pressure disc 18 of each friction clutch is circumferentially positioned and is in sliding fit with the middle diameter section in an axially movable manner.

The present invention is not limited to the above embodiment, and two corresponding shift cams 20 may be disposed between the push plates 16 of the two friction clutches, a gear reduction device 31 and a shift driving motor 27 are respectively mounted on the left and right side walls of the housing 1, the two shift cams 20 are symmetrically located on both sides of the input shaft 2 in the radial direction, and the cam shaft 20a of each shift cam 20 is connected to the shift driving motor 27 disposed on the side through the gear reduction device 31 disposed on the side. Therefore, two gear shifting driving motors 27 can drive two gear shifting cams 20 together under the control of a motor controller to synchronously push one friction clutch to realize gear shifting, so that the thrust of the push disc 16 is more balanced; and under the condition that one gear shifting driving motor fails, the other gear shifting driving motor still keeps gear shifting driving, so that the pure electric vehicle can continue to run, the gear shifting failure during running is avoided, and the use reliability and safety of the pure electric vehicle are improved. Alternatively, two shift drive motors 27 can be used, one for driving a high gear shift and one for driving a low gear shift, under the control of the motor controller.

When the two-gear transmission of the pure electric vehicle works, the traction motor of the pure electric vehicle transmits power to the pressure plates 18 of the two friction clutches through the input shaft 2, the pressure plates 18 drive the driving friction disc 17 to rotate, and the two friction clutches are in a separation state and do not transmit torque under the condition that the driving friction disc 17 is not in contact with the driven friction disc 11. When the gear shifting driving motor 27 is not operated, the push plates 16 of the two friction clutches are contacted with the base circle of the gear shifting cam 20 under the action of the return spring 21, and the two-gear transmission is in a neutral state. When the gear-shifting driving motor 27 starts to work, the gear-shifting cam 20 is driven to rotate towards the direction of the low-speed driving gear 22, the push disc 16 of the friction clutch located in the direction is pushed to move axially, the push disc 16 pushes the pressure disc 18 to move axially through the pressure rod 19, the driving friction disc 17 presses the driven friction disc 11 to form joint, gear shifting is completed, the power of the traction motor is transmitted to the low-speed driving gear 22, the two-gear transmission outputs low-speed power, and the pure electric vehicle runs in a low-speed range. At this time, the push plate 16 of the friction clutch located on the high-speed drive gear 9 is still in contact with the base circle of the shift cam 20, and the friction clutch is in a power interrupted state. When the running needs to be converted into a high-speed range, the gear-shifting driving motor 27 drives the gear-shifting cam 20 to rotate towards the high-speed driving gear 9, the gear-shifting cam 20 pushes the push disc 16 of the friction clutch located in the direction to move axially, the push disc 16 pushes the pressure disc 18 to move axially through the pressure rod 19, the driving friction disc 17 presses the driven friction disc 11 to form engagement, the gear switching from a low gear to a high gear is completed, and the pure electric vehicle runs in the high-speed range. In this process, the push plate 16 of the friction clutch located on the low speed drive gear 22 is returned by the return spring 21 to contact the base circle of the shift cam 20, and the friction clutch is in a power interrupted state and does not transmit the low speed power. When the pushing force of the gear shifting cam 20 on the pushing discs 16 of the two friction clutches is released, the pushing discs 16 of the two friction clutches return under the action of the return spring 21, the two friction clutches do not transmit power, the two-gear transmission is in a neutral state, and the gear shifting driving motor 27 stops working.