Pure electric two-gear speed reducer

Abstract

The invention discloses a pure electric two-gear speed reducer, which relates to the technical field of speed reducers and comprises a driving mechanism and a hydraulic mechanism, the driving mechanism is connected with an output shaft through a total gear train, and the hydraulic mechanism is used for providing pressure oil for the total gear train. Reasonable distribution of the two gear speed ratios is achieved through the total gear train, the power requirement during low-speed operation can be met, and meanwhile the requirement for the highest vehicle speed can be met. In addition, no power interruption exists in the gear shifting process, and the driving comfort is greatly improved. Moreover, the hydraulic mechanism is matched with the total gear train, the gear shifting action is achieved by adjusting pressure oil, necessary cooling lubrication is provided for operation of related parts in the total gear train in the process, stability and smoothness of the operation process of the total gear train are guaranteed, and the conditions of blockage, poor heat dissipation and the like are avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of reducers, and in particular relates to a pure electric two-speed reducer. Background Art

[0002] At present, pure electric vehicles mostly use single-speed reducers. Although they have a simple structure and low cost, they cannot take into account the power and economy of pure electric vehicles. The drive motor cannot always work in the high-efficiency area, resulting in high energy consumption and short life of the drive motor. The performance of the whole vehicle is: poor climbing, starting ability and high-speed performance. Therefore, the application of two-speed reducers is more suitable for pure electric vehicles.

[0003] The reducer for pure electric passenger cars generally uses two pairs of cylindrical gears for two-stage reduction. Each pair of gears is distributed on different support shafts, and each support shaft is supported on the reducer housing by two front and rear bearings. The specific structure and transmission principle are described as follows: the primary transmission driving gear is fixed on the input shaft or is integral with the input shaft, and the input shaft is supported on the reducer housing through the front and rear bearings; the primary transmission driven gear and the secondary transmission driving gear are fixed on the intermediate shaft or are integral with the intermediate shaft, and the intermediate shaft is supported on the reducer housing through the front and rear bearings; the secondary transmission driven gear is fixed on the differential. The power output by the motor is input to the reducer from the input shaft, and is reduced by the primary transmission driving gear and the primary transmission driven gear, and then reduced by the secondary transmission driving gear and the secondary transmission driven gear. The power is finally output through the differential. With the greatly increased motor speed, the vehicle requires an increase in the transmission ratio of the reducer, and the gear center distance needs to be further increased. At the same time, the size of the reducer housing also needs to be increased accordingly to meet the spatial arrangement of the gears.

[0004] Prior art such as an invention patent named reducer, the publication number of this invention patent is WO2015145547A1. This invention provides a reducer, wherein at least a first planetary gear mechanism and a second planetary gear mechanism are arranged in series between an input shaft and an output shaft of the reducer. The reducer is configured in such a way that, in order to further reduce the size and weight of the reducer by reducing the axial length, the entire fourth-stage planetary gear mechanism, which is the second planetary gear mechanism, is arranged around a third-stage planetary gear mechanism, which is the first planetary gear mechanism. The reducer of this invention is large in size and weight. Summary of the invention

[0005] The purpose of the present invention is to provide a pure electric two-speed reducer that can meet the power requirements during low-speed operation while ensuring the maximum vehicle speed requirements, and there is no power interruption during the gear shifting process, thereby greatly improving driving comfort.

[0006] The technical solution adopted by the present invention to achieve the above-mentioned purpose is: A pure electric two-speed reducer comprises a driving mechanism connected to an output shaft via a main gear train, and a hydraulic mechanism for providing pressure oil to the main gear train.

[0007] By adopting the above technical solution and using the main gear train to achieve a reasonable distribution of the two gear ratios, the power demand during low-speed operation can be achieved while ensuring the maximum vehicle speed requirement. In addition, there is no power interruption during the gear shifting process, which greatly improves driving comfort. In addition, the hydraulic mechanism is used in conjunction with the main gear train to achieve the gear shifting action by adjusting the pressure oil, and in this process, the necessary cooling and lubrication are provided for the operation of the relevant components in the main gear train, ensuring the stability and smoothness of the operation of the main gear train and avoiding jamming, poor heat dissipation and other conditions.

[0008] According to one embodiment of the present invention, the total gear train includes a front reduction mechanism, a planetary gear train, a shift mechanism and a secondary reduction mechanism connected in sequence, the front reduction mechanism is connected to the driving mechanism, and the secondary reduction mechanism is connected to the output shaft; the shift mechanism includes a clutch and a brake.

[0009] According to an embodiment of the present invention, the planetary gear train includes a sun gear, a planet carrier assembly and a ring gear, the brake is arranged in cooperation with the outer side of the ring gear, and the clutch is used for cooperation between the sun gear and the planet carrier assembly.

[0010] Furthermore, the front reduction mechanism includes a first-stage reduction driving gear and a first-stage reduction driven gear in a meshing configuration; wherein the first-stage reduction driving gear is connected to the driving mechanism, and the power of the driving mechanism is transmitted to the first-stage reduction driven gear through the first-stage reduction driving gear, thereby realizing the front reduction torque increasing function.

[0011] Furthermore, the driving mechanism includes a driving motor, which serves as a power source for the system and is connected to the first-stage reduction driving gear through a spline. The input shaft transmits power to the first-stage reduction driven gear through the first-stage reduction driving gear.

[0012] The primary reduction driven gear rotates synchronously with the sun gear. When the clutch is engaged, the sun gear and the planetary carrier assembly can rotate synchronously. When the brake is engaged, the ring gear can be locked. The clutch and brake are engaged and disengaged to achieve different gear shifts.

[0013] Furthermore, the clutch and the brake are arranged on the intermediate shaft, wherein the clutch can synchronize the rotation speed of the sun gear and the planetary carrier to achieve a transmission with a speed ratio of 1, and the brake can lock the ring gear to achieve sun gear input and planetary carrier assembly output.

[0014] According to an embodiment of the present invention, the hydraulic mechanism includes a valve plate assembly, and the valve plate assembly is connected to an electric pump.

[0015] The electric pump cooperates with the hydraulic mechanism to achieve the regulation of the valve plate assembly, realize the engagement and disengagement of the clutch through pressure regulation, and ensure the comfort of the shifting process through pressure control. The cooperation of the electric pump and the hydraulic mechanism can ensure the smoothness of the gear shifting process through precise control of pressure; at the same time, the oil supply through the electric pump can meet the cooling needs of the clutch and related moving parts.

[0016] Due to the existence of the clutch, the transmission system can ensure the neutral position from a mechanical structure. In emergency situations such as abnormal control of the high-voltage system and low-voltage failure, it can switch to neutral to ensure the safety of the vehicle.

[0017] According to one embodiment of the present invention, a buffer assembly is provided between the driving mechanism and the total gear train, and the buffer assembly includes an input part, a transmission part and an output part connected in sequence, the input part is connected to the driving mechanism, and the output part is connected to the total gear train; the input part has a buffer planetary gear.

[0018] The outside of the buffer component is fixedly connected to the mounting structure of the drive mechanism, which generally achieves a buffering effect on the drive motor. In this way, when the drive motor in the drive mechanism is started and stopped, the buffer component can buffer the power transmission. During the operation of the drive motor in the drive mechanism, vibrations will be generated. The buffer component can prevent the lateral and longitudinal vibrations from being transmitted to the primary reduction driving wheel, thereby preventing the primary reduction driving wheel and the primary reduction driven wheel from hitting each other, and avoiding the situation where the primary reduction driving wheel and the primary reduction driven wheel cannot be aligned.

[0019] A buffer component is set up. During the power transmission process between the driving mechanism and the main gear train, the connection and transmission link at both ends are realized through the buffer planetary gear, so that the output of the driving motor during the starting process can be smooth, and the reverse torque and impact during the gear shifting process will be absorbed by the buffer component, thereby reducing the damage to the engine caused by torque and impact and increasing the service life of the engine.

[0020] In addition, when the vehicle passes through a bumpy road, the internal parts of the vehicle will vibrate. The buffer component can absorb this vibration and prevent the drive motor from being damaged by the uneven road surface.

[0021] According to an embodiment of the present invention, the input part includes a first base, the first base has a first cavity, a buffer sun gear is arranged in the first cavity, a buffer ring gear is arranged in the first cavity, the buffer ring gear is arranged correspondingly to the side of the buffer sun gear, no less than three buffer planetary gears are arranged between the buffer ring gear and the buffer sun gear, and the buffer sun gear is connected to a driving mechanism. The driving mechanism includes a driving motor, the driving motor has a driving shaft, and the driving shaft is connected to the buffer sun gear shaft.

[0022] By utilizing the cooperation of the buffer planetary gear and the buffer ring gear, the coaxiality of the driving shaft of the driving motor in the driving mechanism and the buffer sun gear is ensured, thereby improving the transmission effect between the driving motor and the primary reducer, and preventing the primary reducer from tooth jumping and tooth hitting due to low coaxiality.

[0023] According to an embodiment of the present invention, the driving shaft passes through the buffer sun gear for sliding connection. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A schematic diagram of a power shift transmission system for a pure electric vehicle; Figure 2 A schematic diagram of another power shift transmission system for a pure electric vehicle; Figure 3 It is a schematic diagram of the structure of the buffer component; Figure 4 It is a three-dimensional schematic diagram of the gear structure; Figure 5 Schematic diagram of the limit ring matching.

[0025] Figure numbers: driving mechanism 1, driving motor 11, driving shaft 12, output shaft 2, hydraulic mechanism 3, valve plate assembly 31, electric pump 32, front reduction mechanism 4, planetary gear train 5, sun gear 51, planetary carrier assembly 52, ring gear 53, secondary reduction mechanism 6, clutch 71, brake 72, buffer assembly 8, input part 81, transmission part 82, output part 83, first base 84, first cavity 85, buffer sun gear 86, buffer ring gear 87, buffer planetary gear 88, gear structure 9, tooth structure 91, groove 92, placement hole 93, fastener 94, limit ring 95, limit base ring 96, limit support ring 97. DETAILED DESCRIPTION

[0026] The technical solution of the present invention is further described in detail below in conjunction with specific implementations and drawings: Embodiment 1: like Figure 1-Figure 3 As shown, this embodiment relates to a power shift transmission system for a pure electric vehicle, specifically to a pure electric two-speed reducer, including a drive mechanism 1, which is connected to an output shaft 2 through a total gear train, and also includes a hydraulic mechanism 3, which is used to provide pressure oil to the total gear train. Among them, the hydraulic mechanism 3 includes a valve plate assembly 31, and the valve plate assembly 31 is connected to an electric pump 32.

[0027] Specifically, the driving mechanism 1 includes a driving motor 11, and the driving motor 11 has a driving shaft 12 for outputting power. The total gear train includes a pre-reduction mechanism 4, a planetary gear train 5, a shift mechanism and a secondary reduction mechanism 6 connected in sequence. The pre-reduction mechanism 4 is connected to the driving mechanism 1, and the secondary reduction mechanism 6 is connected to the output shaft 2. The shift mechanism includes a clutch 71 and a brake 72. Among them, the pre-reduction mechanism 4 includes a primary reduction driving gear and a primary reduction driven gear in a meshing configuration; the planetary gear train 5 includes a sun gear 51, a planetary carrier assembly 52 and a ring gear 53, and the brake 72 is arranged in cooperation with the outer side of the ring gear 53. The clutch 71 is used for the cooperation between the sun gear 51 and the planetary carrier assembly 52; the sun gear 51 is connected to an intermediate shaft, and the clutch 71 and the brake 72 are arranged on the intermediate shaft. The clutch 71 is connected to the secondary reduction mechanism 6; the secondary reduction mechanism 6 includes a secondary reduction driving gear and a secondary reduction driven gear in a meshing configuration.

[0028] Among them, the primary reduction driving gear is coaxially connected with the input shaft, and the input shaft is splined with the output shaft 2 of the driving motor 11. The input shaft transmits power to the primary reduction driven gear through the primary reduction driving gear to realize the pre-deceleration and torque-increasing function. The primary reduction driven gear and the sun gear 51 operate synchronously. After the power is pre-decelerated by the pre-deceleration mechanism 4, it is transmitted to the sun gear 51. Through the planetary gear system 5 composed of the sun gear 51, the planetary carrier assembly 52 and the ring gear 53, the two gears are switched in combination with the clutch 71 and the brake 72, and finally the power is transmitted to the secondary reduction mechanism 6 through the planetary carrier assembly 52. ​​Among them, the clutch 71 can synchronize the speed of the sun gear 51 and the planetary carrier to realize the transmission with a speed ratio of 1, and the brake 72 can lock the ring gear 53 to realize the input of the sun gear 51 and the output of the planetary carrier assembly 52. ​​The secondary reduction driving gear is connected to the clutch 71, and the secondary reduction driven gear is connected to the output shaft 2. In this way, the power is finally transmitted to the output shaft 2 by using the secondary reduction structure, and then transmitted to the wheels through the axle to realize the driving of the vehicle.

[0029] The first gear power transmission path of the vehicle using the pure electric two-speed reducer of this embodiment is: the brake 72 is engaged, the clutch 71 is disengaged, and the power of the drive motor 11 is transmitted to the sun gear 51 through the first-stage reduction driving gear and the first-stage reduction driven gear. Since the brake 72 locks the gear ring 53, the power will be transmitted to the second-stage reduction driving gear and the second-stage reduction driving gear through the planetary carrier assembly 52, thereby transmitting the power to the output shaft 2 and finally to the wheels. And the power transmission by speed ratio is realized.

[0030] Second gear power transmission path: brake 72 is disengaged, clutch 71 is engaged, and the power of drive motor 11 is transmitted to sun gear 51 through primary reduction driving gear and primary reduction driven gear. Since clutch 71 is engaged, sun gear 51 and planet carrier assembly 52 are fixed together at this time, and power will be directly transmitted to secondary reduction driving gear and secondary reduction driving gear through planet carrier assembly 52, thereby transmitting power to output shaft 2 and finally to wheels. And power transmission with speed ratio of 1 is realized.

[0031] During the gear shifting process, the torque of the clutch 71 and the brake 72 alternately increases and decreases during the engagement and disengagement process, ensuring that the power is not interrupted during the gear switching process and improving the comfort of the gear shifting.

[0032] When reversing, the drive motor 11 runs in the reverse direction, the clutch 71 or the brake 72, and the power of the drive motor 11 is transmitted to the sun gear 51 through the primary reduction driving gear and the primary reduction driven gear, and then transmitted to the secondary reduction driving gear and the secondary reduction driving gear through the planetary carrier assembly 52, thereby transmitting the power to the output shaft 2, and finally to the wheels, realizing the reversing function.

[0033] In the above process, the electric pump 32 cooperates with the hydraulic mechanism 3 to achieve the regulation of the valve plate assembly 31, realizes the engagement and separation of the clutch 71 through pressure regulation, and ensures the comfort of the shifting process through pressure control. By using the cooperation of the electric pump 32 and the hydraulic mechanism 3, the smoothness of the gear shifting process can be ensured through the precise control of the pressure; at the same time, the oil supply through the electric pump 32 can meet the cooling requirements of the clutch 71 and related operating parts.

[0034] Due to the existence of the clutch 71, the transmission system can ensure the neutral position from a mechanical structure. In an emergency, such as abnormal control of the high-pressure system and failure of the low-pressure system, the transmission system can be switched to the neutral position to ensure the safety of the vehicle.

[0035] A buffer assembly 8 is provided between the driving mechanism 1 and the total gear train, and the buffer assembly 8 includes a mounting housing, and the interior of the mounting housing is provided with an input portion 81, a transmission portion 82, and an output portion 83 connected in sequence, wherein the output portion 83 is a shaft structure, which cooperates with the primary reduction driving gear in the front reduction mechanism 4. The input portion 81 is connected to the driving mechanism 1 through a shaft structure, and the output portion 83 is connected to the total gear train through a shaft structure; the input portion 81 has a buffer planetary gear. The mounting housing of the buffer assembly 8 is fixedly connected to the mounting structure of the driving mechanism 1, and is utilized to achieve a buffering effect on the driving motor 11.

[0036] Specifically, the input part 81 includes a first base 84, the first base 84 has a first cavity 85, a buffer sun gear 86 is provided in the first cavity 85, a buffer ring gear 87 is provided in the first cavity 85, the buffer ring gear 87 and the buffer sun gear 86 are arranged at corresponding side intervals, and no less than three buffer planetary gears 88 are provided between the buffer ring gear 87 and the buffer sun gear 86. The buffer sun gear 86 is connected to the driving shaft 12 of the driving motor 11 through a shaft structure and splines, and the buffer planetary gear 88 is dynamically connected to the transmission part 82 through a planetary carrier.

[0037] Furthermore, the first base 84 can be set as a hollow pancake-shaped structure with through holes on both sides for the shaft structure to follow and cooperate. The drive motor 11 operates to drive the buffer sun gear 86 connected thereto to rotate, and the buffer ring gear 87 matched with the buffer sun gear 86 rotates the buffer planetary gear 88 arranged around the buffer sun gear 86, thereby transmitting the power of the drive motor 11 to the transmission part 82.

[0038] The drive shaft 12 can be configured to be slidably connected to the buffer sun gear 86. In this way, during the operation of the drive motor 11, the drive shaft 12 can move back and forth axially relative to the buffer sun gear 86, which can avoid setbacks during the starting, running and braking of the wheels, improve the buffering of lateral and longitudinal vibrations, and improve driving comfort.

[0039] In addition, the buffer planetary gear 88 rotates around the buffer sun gear 86 while also rotating. During the rotation process, the buffer planetary gear 88 may produce a certain displacement along the axis, which is conducive to ensuring the smoothness of power transmission and can absorb and consume the vibration energy generated during the power transmission process. In particular, during the start and stop process of the drive motor 11 in the drive mechanism 1, the buffer component 8 can achieve buffering of power transmission. During the operation of the drive motor 11 in the drive mechanism 1, vibrations will be generated. The buffer component 8 can prevent the lateral and longitudinal vibrations from being transmitted to the primary reduction driving wheel, thereby preventing the occurrence of tooth collision between the primary reduction driving wheel and the primary reduction driven wheel, and avoiding the situation where the primary reduction driving wheel and the primary reduction driven wheel cannot be aligned.

[0040] By utilizing the cooperation between the buffer planetary gear 88 and the buffer ring gear 87, the coaxiality between the drive shaft 12 of the drive motor 11 in the drive mechanism 1 and the buffer sun gear 86 is ensured, thereby improving the transmission effect between the drive motor 11 and the primary reducer, and preventing the primary reducer from skipping teeth or hitting teeth due to low coaxiality.

[0041] In addition, the use of multiple buffer planetary gears 88 can ensure uniform load distribution among the multiple buffer planetary gears 88 and uniform load distribution along the meshing tooth width, and has good processing and assembly processes, so that the buffer planetary gear 88 transmission has a high load-bearing capacity, less vibration and noise, reducing the probability of abnormal noise during vehicle driving and extending the service life.

[0042] The transmission part 82 can be set to a structure similar to the input part 81, including a transmission sun gear 51, a transmission ring gear 53 arranged corresponding to the side interval of the transmission sun gear 51, and a plurality of transmission planetary gears arranged between the transmission ring gear 53 and the transmission sun gear 51. Generally, the transmission planetary gear and the planetary carrier structure cooperate with the buffer planetary gear 88 and the planetary carrier structure of the input part 81, and the transmission sun gear 51 is connected to the shaft structure of the output part 83; or, the transmission sun gear 51 cooperates with the buffer planetary gear 88 and the planetary carrier structure of the input part 81, and the transmission planetary gear and the planetary carrier structure are connected to the shaft structure of the output part 83. In this way, the transmission part 82 has a function similar to that of the input part 81.

[0043] In this way, during the process of power transmission from the driving motor 11 to the front reduction mechanism 4, secondary buffering is achieved through the input part 81 and the transmission part 82 in the buffer assembly 8, which can effectively reduce vibration interference and improve the smoothness and stability of power transmission.

[0044] In addition, in order to simplify the structure, the specific structure of the transmission part 82 can also be set as a worm gear structure, and the external teeth of the worm gear structure are meshed with the buffer planetary gear 88 and the shaft of the planetary carrier in the input part 81; the worm gear structure is cooperatively connected with the shaft of the output part 83.

[0045] A buffer component 8 is provided. During the power transmission between the driving mechanism 1 and the main gear train, the connection and transmission link between the two ends are realized through the input part 81 and the transmission part 82, so that the output of the driving motor 11 during the starting process can be smooth, and the reverse torque and impact received during the gear shifting process will be absorbed by the buffer component 8, thereby reducing the damage to the engine caused by the torque and impact and increasing the service life of the engine.

[0046] In addition, when the vehicle passes through a bumpy road section, the internal parts of the vehicle will vibrate. The buffer assembly 8 can absorb the vibration and prevent the drive motor 11 from being damaged by the uneven road surface.

[0047] Embodiment 2: like Figure 4 and Figure 5 As shown, a pure electric two-speed reducer according to another embodiment of the present invention is different from Example 1 in that a groove 92 is provided on the tooth structure 91 of each gear structure 9 in the total gear train.

[0048] Furthermore, the groove 92 is in an arc shape.

[0049] The groove 92 is provided in the tooth structure 91 of the relevant gear to store lubricating oil, ensure the distribution of lubricating oil on the gear surface, thereby improving the lubrication effect; and the provision of the groove 92 helps to reduce the contact stress of the rack and ensure the transmission effect. In addition, during the operation of the gear, debris will be generated due to wear or jamming, and the groove 92 can be used to collect the debris to avoid the debris being mixed in the meshing surface of the tooth to cause meshing interference, tooth jamming and other problems.

[0050] The gear structure 9 is surrounded by at least three placement holes 93 , which are arranged parallel to the axis of the gear, and fasteners 94 are arranged in the placement holes 93 .

[0051] The method of surrounding the gear with the fastener 94 can, on the one hand, increase the gear counterweight, thereby reducing the vibration of the gear during rotation; on the other hand, the fastener 94 can be used to collect and absorb lubricating oil, thereby further improving the gear lubrication.

[0052] A limiting ring 95 is disposed in the placement hole 93 , and the limiting ring 95 includes a limiting base ring 96 , and one end of the limiting base ring 96 is provided with no less than two limiting support rings 97 , and the limiting support rings 97 distributed on both sides of the limiting base ring 96 are arranged to be tilted back to back.

[0053] A limiting ring 95 is provided inside the fastener 94 to provide a storage space for lubricating oil, and the limiting ring 95 can also be used to ensure the assembly stability of the fastener 94 and the gear. In particular, the matching structure of the limiting base ring 96 and the limiting support ring 97 enables the limiting ring 95 to have a certain deformation ability, thereby ensuring the tightness of the fastener 94 and the inner wall of the placement hole 93 to prevent it from falling off.

[0054] Based on this, since the fastener 94 can collect lubricating oil, the centrifugal force can be used to enhance the lubrication effect on the side of the gear when the gear rotates, and the lubricating oil is caused to flow from the side of the gear to the gear meshing part under the centrifugal action and be collected by the arc groove 92, that is, the storage effect of the groove 92 on the lubricating oil is improved.

[0055] In addition, the setting of the limit support ring 97 intercepts the lubricating oil inside the placement hole 93, that is, it can prevent the lubricating oil inside the placement hole 93 from overflowing all at once, thereby helping to improve the utilization rate of the lubricating oil, ensuring the lubrication effect while avoiding adverse consequences such as idling of the gear meshing surface due to excessive lubricating oil.

[0056] The embodiments described above provide a detailed description of the technical solutions of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, supplements or similar substitutions made within the scope of the principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A pure electric two-speed reducer, comprising a drive mechanism (1), wherein the drive mechanism (1) is connected to an output shaft (2) via a total gear train, and is characterized in that: It also includes a hydraulic mechanism (3), wherein the hydraulic mechanism (3) is used to provide pressure oil to the main gear train.

2. A pure electric two-speed reducer according to claim 1, characterized in that: The total gear train comprises a front reduction mechanism (4), a planetary gear train (5), a shift mechanism and a secondary reduction mechanism (6) which are connected in sequence, the front reduction mechanism (4) being connected to the drive mechanism (1), and the secondary reduction mechanism (6) being connected to the output shaft (2); The gear shifting mechanism comprises a clutch (71) and a brake (72).

3. A pure electric two-speed reducer according to claim 2, characterized in that: The planetary gear train (5) comprises a sun gear (51), a planet carrier assembly (52) and a ring gear (53); the brake (72) is arranged in cooperation with the outer side of the ring gear (53); and the clutch (71) is used for cooperation between the sun gear (51) and the planet carrier assembly (52).

4. A pure electric two-speed reducer according to claim 1, characterized in that: The hydraulic mechanism (3) comprises a valve plate assembly (31), and the valve plate assembly (31) is connected to an electric pump (32).

5. A pure electric two-speed reducer according to claim 1, characterized in that: A buffer assembly (8) is provided between the driving mechanism (1) and the total gear train, the buffer assembly (8) comprising an input portion (81), a transmission portion (82), and an output portion (83) connected in sequence, the input portion (81) being connected to the driving mechanism (1), and the output portion (83) being connected to the total gear train; The input part (81) has a buffer planetary gear.

6. A pure electric two-speed reducer according to claim 5, characterized in that: The input part (81) comprises a first base (84), the first base (84) having a first cavity (85) therein, a buffer sun gear (86) being arranged in the first cavity (85), a buffer ring gear (87) being arranged in the first cavity (85), the buffer ring gear (87) being arranged in correspondence with the side surfaces of the buffer sun gear (86) at intervals, no less than three buffer planetary gears (88) being arranged between the buffer ring gear (87) and the buffer sun gear (86), and the buffer sun gear (86) being connected to the driving mechanism (1).

7. A pure electric two-speed reducer according to claim 6, characterized in that: The drive mechanism (1) comprises a drive motor (11), wherein the drive motor (11) has a drive shaft (12), and the drive shaft (12) penetrates the buffer sun gear (86) in sliding connection.

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