Single-planet-row power holding type three-gear automatic transmission

Abstract

The invention discloses a single planet row power holding type three-gear automatic transmission, which relates to the technical field of automobile automatic transmissions, and comprises a planet row, an intermediate shaft, a main speed reducer and a differential mechanism which are arranged in a transmission shell, wherein the planet row is in transmission connection with the motor through the input shaft, the three-gear clutch is arranged between the input shaft and the planet carrier, the planet carrier brake is arranged between the planet carrier and the transmission shell, and the gear ring brake is arranged between the gear ring and the transmission shell; the input shaft is connected with the intermediate shaft through a gear; the intermediate shaft comprises a right intermediate shaft, a main intermediate shaft and a left intermediate shaft; the right intermediate shaft is connected with the main intermediate shaft through a second-gear clutch, and the main intermediate shaft is connected with the left intermediate shaft through a high-low-gear clutch; the main intermediate shaft is in transmission connection with a differential mechanism through a main reducer, and the differential mechanism is in transmission connection with driving wheels through half shafts. The electric vehicle can run in three gears, the running efficiency of the motor is improved, and power uninterrupted gear shifting of the electric vehicle is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of automobile automatic transmissions, in particular to a single planetary gear power-holding type three-speed automatic transmission. Background Art

[0002] Since the motor has a large speed regulation range and has the characteristics of constant torque at low speed and constant power at high speed, in theory, the motor can achieve stepless speed regulation without the need for a transmission. Therefore, in terms of power transmission, electric vehicles often cancel the transmission and use a fixed speed ratio. But in fact, there are many shortcomings in driving vehicles in this way: first, the motor speed regulation range is difficult to take into account both high torque and maximum speed; second, when the wheels are directly driven, the motor operating point is often in a low efficiency area, which not only wastes electric energy, but also increases the requirements for the motor, resulting in poor vehicle driving economy and limited cruising range. Therefore, in order to improve the efficiency of the motor during operation and reduce the requirements of electric vehicles for motors and batteries, it is necessary to add a multi-speed ratio transmission to the electric vehicle.

[0003] At present, some electric vehicles in China are equipped with transmissions, but the basic structure is still a traditional parallel shaft automatic transmission. This type of transmission is often large in size. At the same time, due to the presence of synchronizers, it is impossible to overcome power interruption when shifting gears, and the comfort of use is poor. In theory, two planetary gear trains can also be used to form a multi-speed transmission, but the structure is complex, the transmission efficiency is low, and the processing precision requirements are high. The current commercialized electric vehicle transmission usually only has two gears, which are used for low-speed starting and high-speed cruising of electric vehicles respectively. However, when driving on urban roads, it is often necessary to drive at a medium speed. Simply driving in high gear or low gear will reduce the efficiency of the motor. Summary of the invention

[0004] The purpose of the present invention is to provide a single planetary gear power-holding three-speed automatic transmission in order to solve at least one of the above technical problems.

[0005] In the first aspect, an embodiment of the present invention provides a single planetary gear power retention type three-speed automatic transmission, comprising: a planetary gear, an intermediate shaft, a main reducer and a differential arranged in a transmission housing; wherein the planetary gear is connected to the electric motor of the electric vehicle through an input shaft transmission connection, a three-speed clutch is arranged between the input shaft and the planetary carrier of the planetary gear, a planetary carrier brake is arranged between the planetary carrier and the transmission housing, and a ring gear brake is arranged between the ring gear of the planetary gear and the transmission housing; the input shaft is connected to the intermediate shaft through gears; the intermediate shafts include a right intermediate shaft, a main intermediate shaft and a left intermediate shaft; the left end of the right intermediate shaft is connected to the right end of the main intermediate shaft through a second-speed clutch, and the left end of the main intermediate shaft is connected to the right end of the left intermediate shaft through a high-low gear clutch; the main intermediate shaft is connected to the differential through the main reducer, and the differential is connected to the driving wheel of the electric vehicle through a half shaft.

[0006] Furthermore, one end of the input shaft is connected to the electric motor, and the other end of the input shaft extends into the transmission case, and the planetary gear, the third-speed clutch and the planetary carrier brake are installed on the input shaft.

[0007] Furthermore, the planetary gear row also includes a sun gear and a plurality of planetary gears; the sun gear is fixedly connected to the end of the input shaft extending into the transmission case, the planetary carrier is sleeved on the input shaft, the plurality of planetary gears are evenly distributed around the sun gear, the planetary carrier is fixedly connected to the plurality of planetary gears, the ring gear is installed at the end of the ring gear brake, the plurality of planetary gears are meshed with the outside of the sun gear, and the plurality of planetary gears are meshed with the inside of the ring gear.

[0008] Furthermore, the ring gear brake and the planetary carrier brake are both mounted on the inner wall of the transmission housing, the rotating part of the ring gear brake is relatively fixed to the ring gear, and the rotating part of the planetary carrier brake is relatively fixed to the planetary carrier.

[0009] Furthermore, one end of the planet carrier is fixedly connected to a high and low gear driving gear, and the high and low gear driving gear is sleeved on the input shaft; the left intermediate shaft is provided with a high and low gear driven gear, and the high and low gear driving gear is meshed with the high and low gear driven gear.

[0010] Furthermore, a second-gear input shaft is arranged at one end of the planetary gear row facing away from the input shaft, one end of the second-gear input shaft extends into the transmission case and is fitted with a second-gear driving gear, and the other end of the second-gear input shaft is mounted on the transmission case through a bearing; the second-gear driving gear is fixedly connected to the ring gear; a second-gear driven gear is mounted on the right intermediate shaft, and the second-gear driving gear and the second-gear driven gear are connected through an idler gear transmission.

[0011] Furthermore, one end of the idler wheel is fixedly connected to an idler wheel shaft, and the other end of the idler wheel shaft is mounted on the transmission case through a bearing; the second gear driving gear is constantly meshed with the idler wheel, and the idler wheel is constantly meshed with the second gear driven gear at the same time.

[0012] Furthermore, the main reducer includes a main reducer driving gear and a main reducer driven gear; the main reducer driving gear is installed on the main intermediate shaft, and the main reducer driven gear is fixedly connected to the differential; the main reducer driving gear is meshed with the main reducer driven gear; the half shaft includes a left half shaft and a right half shaft, and the two ends of the differential are respectively installed on the left half shaft and the right half shaft.

[0013] Furthermore, the high-low gear clutch, the second gear clutch and the third gear clutch include electromagnetic clutches or mechanical clutches; the ring gear brake and the planetary carrier brake include electromagnetic brakes or mechanical brakes.

[0014] The present invention provides a single planetary gear power-holding three-speed automatic transmission, which adopts a single-row planetary gear system as a speed change mechanism. The transmission has a small outer size, has the advantage of being lightweight, and is convenient for vehicle layout. The gear shifting is performed by sliding friction of three clutches and two brakes without power interruption, which can significantly improve the smoothness of gear shifting. The three-speed shifting can effectively improve the efficiency of the motor. The technical problems existing in the prior art, such as complex structure, low transmission efficiency, and poor comfort caused by the inability to overcome power interruption during gear shifting, are alleviated. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0016] Figure 1 A schematic structural diagram of a single planetary gear power-holding three-speed automatic transmission provided by an embodiment of the present invention;

[0017] Figure 2 A schematic diagram of a power transmission route of a single planetary gear power-holding type three-speed automatic transmission in first gear provided by an embodiment of the present invention;

[0018] Figure 3 A schematic diagram of a power transmission route of a single planetary gear power-holding type three-speed automatic transmission in second gear provided by an embodiment of the present invention;

[0019] Figure 4 A schematic diagram of the power transmission route of a single planetary gear power-holding type three-speed automatic transmission in third gear provided by an embodiment of the present invention.

[0020] In the figure: 1, input shaft, 2, high and low gear driving gear, 3, planetary carrier, 4, planetary carrier brake, 5, third gear clutch, 6, ring gear brake, 7, ring gear, 8, transmission case, 9, second gear driving gear, 10, second gear input shaft, 11, sun gear, 12, planetary gear, 13, idler shaft, 14, idler, 15, second gear driven gear, 16, right intermediate shaft, 17, second gear clutch, 18, right half shaft, 19, bearing, 20, main reducer driving gear, 21, main reducer driven gear, 22, differential, 23, left half shaft, 24, high and low gear driven gear, 25, left intermediate shaft, 26, high and low gear clutch, 27, main intermediate shaft, 28, motor. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] Figure 1 1 is a schematic diagram of the structure of a single planetary gear power-holding three-speed automatic transmission according to an embodiment of the present invention. Figure 1 As shown, the transmission includes: a planetary gear, an intermediate shaft, a main reducer and a differential 22 arranged in a transmission housing 8.

[0023] Specifically, Figure 1 As shown, the planetary gear is connected to the electric motor 28 of the electric vehicle through the input shaft 1, a third-speed clutch 5 is arranged between the input shaft 1 and the planetary carrier 3 of the planetary gear, a planetary carrier brake 4 is arranged between the planetary carrier 3 and the transmission case 8, and a ring gear brake 6 is arranged between the ring gear 7 of the planetary gear 3 and the transmission case 8.

[0024] Specifically, the input shaft 1 is connected to the intermediate shaft through gears.

[0025] Specifically, Figure 1 As shown, the intermediate shaft includes a right intermediate shaft 16, a main intermediate shaft 27 and a left intermediate shaft 25; the left end of the right intermediate shaft 16 is connected to the right end of the main intermediate shaft 27 through a second gear clutch 17, and the left end of the main intermediate shaft 27 is connected to the right end of the left intermediate shaft 25 through a high and low gear clutch 26.

[0026] The main intermediate shaft 27 is drivingly connected to the differential 22 via the main reducer, and the differential 22 is drivingly connected to the driving wheels of the electric vehicle via the half shafts.

[0027] Specifically, Figure 1 As shown, one end of the input shaft 1 is connected to the motor 28 , and the other end of the input shaft 1 extends into the transmission case 8 . A planetary gear, a third-speed clutch 5 and a planetary carrier brake 4 are installed on the input shaft 1 .

[0028] The planetary gear row also includes a sun gear 11 and multiple planetary gears 12; the sun gear 11 is fixedly connected to the end of the input shaft 1 extending into the transmission housing 8, the planet carrier 3 is sleeved on the input shaft 1, and multiple planetary gears 12 are evenly distributed around the sun gear 11. The planet carrier 3 is fixedly connected to the multiple planetary gears 12, and the ring gear 7 is installed at the end of the ring gear brake 6. The multiple planetary gears 12 are meshed with the sun gear 11 externally, and the multiple planetary gears 12 are meshed with the ring gear 7 internally.

[0029] The ring gear brake 6 and the planetary carrier brake 4 are both mounted on the inner wall of the transmission housing 8 . The rotating part of the ring gear brake 6 is relatively fixed to the ring gear 7 , and the rotating part of the planetary carrier brake 4 is relatively fixed to the planetary carrier 3 .

[0030] Specifically, when the ring gear brake 6 is engaged, the ring gear 7 is interconnected with the transmission case 8 ; when the planet carrier brake 4 is engaged, the planet carrier 3 is interconnected with the transmission case 8 .

[0031] Specifically, Figure 1 As shown, one end of the planet carrier 3 is also fixedly connected to a high and low gear driving gear 2, and the high and low gear driving gear 2 is sleeved on the input shaft 1; a high and low gear driven gear 24 is arranged on the left intermediate shaft 25, and the high and low gear driving gear 2 is meshed with the high and low gear driven gear 24.

[0032] A second gear input shaft 10 is arranged at one end of the planetary gearbox facing away from the input shaft 1. One end of the second gear input shaft 10 extends into the transmission case 8 and is fitted with a second gear driving gear 9. The other end of the second gear input shaft 10 is mounted on the transmission case 8 through a bearing 19. The second gear driving gear 9 is fixedly connected to the ring gear 7.

[0033] A second-gear driven gear 15 is mounted on the right intermediate shaft 16 , and the second-gear driving gear 9 is transmission-connected to the second-gear driven gear 15 via an idler gear 14 .

[0034] Specifically, Figure 1 As shown, one end of the idler gear 14 is fixedly connected to the idler gear shaft 13, and the other end of the idler gear shaft 13 is mounted on the transmission housing 8 through a bearing 19; the second gear driving gear 9 is constantly meshed with the idler gear 14, and the idler gear 14 is constantly meshed with the second gear driven gear 15 at the same time.

[0035] Specifically, Figure 1As shown, the main reducer includes a main reducer driving gear 20 and a main reducer driven gear 21; the main reducer driving gear 20 is installed on the main intermediate shaft 27, and the main reducer driven gear 21 is fixedly connected to the differential 22; the main reducer driving gear 20 is meshed with the main reducer driven gear 21.

[0036] like Figure 1 As shown, the half shafts include a left half shaft 23 and a right half shaft 18, and both ends of the differential 22 are mounted on the left half shaft 23 and the right half shaft 18 respectively.

[0037] Preferably, in the embodiment of the present invention, the left intermediate shaft 25 , the right intermediate shaft 16 , the left half shaft 23 and the right half shaft 18 are respectively mounted on the transmission housing 8 via bearings 19 .

[0038] Specifically, an embodiment of the present invention provides a single planetary gear power holding type three-speed automatic transmission, which interconnects the main intermediate shaft 27 and the right intermediate shaft 16 when the second gear clutch 17 is engaged; interconnects the sun gear 11 and the planetary carrier 3 when the third gear clutch 5 is engaged; and interconnects the left intermediate shaft 25 and the main intermediate shaft 27 when the high and low gear clutch 26 is engaged.

[0039] Optionally, the high and low gear clutch 26, the second gear clutch 17 and the third gear clutch 5 include electromagnetic clutches or mechanical clutches.

[0040] For example, the high and low gear clutch 26 may be an electromagnetic clutch or a mechanical clutch.

[0041] For example, the second gear clutch 17 may be an electromagnetic clutch or a mechanical clutch.

[0042] For example, the third-speed clutch 5 may be an electromagnetic clutch or a mechanical clutch.

[0043] Optionally, the ring gear brake 6 and the planet carrier brake 4 include electromagnetic brakes or mechanical brakes.

[0044] For example, the ring gear brake 6 may be an electromagnetic brake or a mechanical brake.

[0045] For example, the planetary carrier brake 4 may be an electromagnetic brake or a mechanical brake.

[0046] The working principle and working process of the single planetary gear power holding type three-speed automatic transmission proposed by the present invention are described in detail below in conjunction with the accompanying drawings.

[0047] Figure 2 The figure is a schematic diagram of the power transmission route of a single planetary gear power-holding type three-speed automatic transmission in the first gear according to an embodiment of the present invention, wherein the first gear of the automatic transmission is used for starting, climbing, low-speed driving and reversing of the vehicle. Figure 2As shown, when the transmission is in the first gear, the second gear clutch 17, the third gear clutch 5, and the planetary carrier brake 4 are all disconnected, the high and low gear clutch 26 and the ring gear brake 6 are all engaged, and the power of the motor 28 is transmitted to the sun gear 11 of the planetary gear system through the input shaft 1. At this time, since the ring gear 7 is fixed on the transmission case 8, a speed ratio greater than 1 is generated between the sun gear 11 and the planetary carrier 3 of the planetary gear system through the planetary gear 12. The power is transmitted to the high and low gear driving gear 2 through the planetary gear 12 and the planetary carrier 3, and then transmitted to the left half shaft 23 and the right half shaft 18 through the high and low gear driven gear 24, the left intermediate shaft 25, the high and low gear clutch 26, the main intermediate shaft 27, the main reducer driving gear 20, the main reducer driven gear 21, and the differential 22, thereby driving the wheels.

[0048] Figure 3 The figure is a schematic diagram of the power transmission route of a single planetary gear power retention type three-speed automatic transmission in the second gear according to an embodiment of the present invention, wherein the second gear of the automatic transmission is used for medium-speed driving of the automobile. Figure 3 As shown, when the transmission is in the second gear, the third gear clutch 5, the high and low gear clutch 26, and the ring gear brake 6 are all disconnected, the second gear clutch 17 and the planetary carrier brake 4 are all engaged, and the power of the motor 28 is transmitted to the sun gear 11 of the planetary gear system through the input shaft 1. At this time, since the planetary carrier 3 is fixed on the transmission case 8, a reverse speed ratio greater than 1 but less than the first gear speed ratio is generated between the sun gear 11 and the ring gear 7 of the planetary gear system through the planetary gear 12. The power is transmitted to the left half shaft 23 and the right half shaft 18 through the ring gear 7, the second gear driving gear 9, the idler gear 14, the second gear driven gear 15, the right intermediate shaft 16, the second gear clutch 17, the main intermediate shaft 27, the main reducer driving gear 20, the main reducer driven gear 21, and the differential 22, thereby driving the wheels. In this process, the power output to the wheels can be kept in the same direction as the input shaft 1 through the idler gear 14.

[0049] Figure 4 A schematic diagram of the power transmission route of a single planetary gear power-holding three-speed automatic transmission in the third gear according to an embodiment of the present invention, wherein the third gear of the automatic transmission is used for high-speed driving of the car, and can also be called a direct gear. Figure 4As shown, when the transmission is in the third gear, the second gear clutch 17, the ring gear brake 6, and the planetary carrier brake 4 are all disconnected, the third gear clutch 5 and the high and low gear clutch 26 are all engaged, and the power of the motor 28 is transmitted to the sun gear 11 of the planetary gear system through the input shaft 1. At this time, since the sun gear 11 is interconnected with the planetary carrier 3, the planetary gear system rotates as a whole, and the speed ratio between the sun gear 11 and the planetary carrier 3 of the planetary gear system is 1. The power is transmitted to the high and low gear driving gear 2 through the planetary gear 12 and the planetary carrier 3, and then transmitted to the left half shaft 23 and the right half shaft 18 through the high and low gear driven gear 24, the left intermediate shaft 25, the high and low gear clutch 26, the main intermediate shaft 27, the main reducer driving gear 20, the main reducer driven gear 21, and the differential 22, thereby driving the wheels.

[0050] When the second gear clutch 17, the third gear clutch 5, the high and low gear clutch 26, the ring gear brake 6, and the planetary carrier brake 4 are all disconnected, the transmission is in neutral, which can meet the needs of towing or repairing the electric vehicle.

[0051] When the transmission switches from the first gear to the second gear, the high and low gear clutch 26 and the ring gear brake 6 are gradually disconnected, while the second gear clutch 17 and the planetary carrier brake 4 are gradually engaged, and the third gear clutch 5 remains disconnected, so that the ring gear 7 is gradually disconnected from the transmission case 8, the left intermediate shaft 25 is gradually disconnected from the main intermediate shaft 27, the planetary carrier 3 is gradually interconnected with the transmission case 8, and the right intermediate shaft 16 is gradually interconnected with the main intermediate shaft 27. When the planetary carrier 3 is fully engaged with the transmission case 8, and the right intermediate shaft 16 is fully engaged with the main intermediate shaft 27, the switch from the first gear to the second gear is completed.

[0052] When the transmission switches from the second gear to the first gear, the second gear clutch 17 and the planetary carrier brake 4 are gradually disconnected, and at the same time, the high and low gear clutch 26 and the ring gear brake 6 are gradually engaged, and the third gear clutch 5 remains disconnected, so that the planetary carrier 3 is gradually disconnected from the transmission case 8, the right intermediate shaft 16 is gradually disconnected from the main intermediate shaft 27, the ring gear 7 is gradually engaged with the transmission case 8, and the left intermediate shaft 25 is gradually engaged with the main intermediate shaft 27. When the ring gear 7 is fully engaged with the transmission case 8 and the left intermediate shaft 25 is fully engaged with the main intermediate shaft 27, the switch from the second gear to the first gear is completed.

[0053] When the transmission switches from the second gear to the third gear, the second gear clutch 17 and the planetary carrier brake 4 are gradually disconnected, and at the same time, the third gear clutch 5 and the high and low gear clutch 26 are gradually engaged, and the ring gear brake 6 remains disconnected, so that the planetary carrier 3 is gradually disconnected from the transmission case 8, the right intermediate shaft 16 is gradually disconnected from the main intermediate shaft 27, the sun gear 11 is gradually engaged with the planetary carrier 3, and the left intermediate shaft 25 is gradually engaged with the main intermediate shaft 27. When the sun gear 11 is fully engaged with the planetary carrier 3, and the left intermediate shaft 25 is fully engaged with the main intermediate shaft 27, the switch from the second gear to the third gear is completed.

[0054] When the transmission switches from the third gear to the second gear, the third gear clutch 5 and the high and low gear clutch 26 are gradually disconnected, while the second gear clutch 17 and the planetary carrier brake 4 are gradually engaged, and the ring gear brake 6 remains disconnected, so that the sun gear 11 is gradually disconnected from the planetary carrier 3, the left intermediate shaft 25 is gradually disconnected from the main intermediate shaft 27, the planetary carrier 3 is gradually engaged with the transmission case 8, and the right intermediate shaft 16 is gradually engaged with the main intermediate shaft 27. When the planetary carrier 3 is fully engaged with the transmission case 8, and the right intermediate shaft 16 is fully engaged with the main intermediate shaft 27, the switch from the third gear to the second gear is completed.

[0055] When the transmission switches from the first gear to the third gear, the ring gear brake 6 is gradually disconnected, and at the same time the third gear clutch 5 is gradually engaged, the second gear clutch 17 and the planetary carrier brake 4 remain disconnected, and the high and low gear clutch 26 remain engaged, so that the ring gear 7 is gradually disconnected from the transmission case 8, and the sun gear 11 is gradually engaged with the planetary carrier 3. When the sun gear 11 is fully engaged with the planetary carrier 3, the switch from the first gear to the third gear is completed.

[0056] When the transmission switches from the third gear to the first gear, the third gear clutch 5 is gradually disconnected, and at the same time the ring gear brake 6 is gradually engaged, the second gear clutch 17 and the planetary carrier brake 4 remain disconnected, and the high and low gear clutch 26 remains engaged, so that the sun gear 11 is gradually disconnected from the planetary carrier 3, and the ring gear 7 is gradually engaged with the transmission case 8. When the ring gear 7 is fully engaged with the transmission case 8, the switch from the third gear to the first gear is completed.

[0057] From the above description, it can be seen that an embodiment of the present invention provides a single planetary gear power-holding three-speed automatic transmission, which adopts a single-row planetary gear system as a speed change mechanism. The transmission has a small outer size, has the advantage of being lightweight, and is convenient for vehicle layout. The gear shifting is performed through the sliding friction of three clutches and two brakes without power interruption, which can significantly improve the smoothness of gear shifting. The three-speed shifting can effectively improve the efficiency of the motor.

[0058] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0059] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A single planetary gear power holding type three-speed automatic transmission, characterized in that: include: The planetary gear, intermediate shaft, main reducer and differential are arranged in the transmission case; wherein, The planetary gear is connected to the electric motor of the electric vehicle through an input shaft, a third-speed clutch is arranged between the input shaft and the planetary carrier of the planetary gear, a planetary carrier brake is arranged between the planetary carrier and the transmission case, and a ring gear brake is arranged between the ring gear of the planetary gear and the transmission case; The input shaft is connected to the intermediate shaft via a gear; The intermediate shaft comprises a right intermediate shaft, a main intermediate shaft and a left intermediate shaft; the left end of the right intermediate shaft is connected to the right end of the main intermediate shaft through a second gear clutch, and the left end of the main intermediate shaft is connected to the right end of the left intermediate shaft through a high and low gear clutch; The main intermediate shaft is drivingly connected to the differential through a main reducer, and the differential is drivingly connected to the driving wheels of the electric vehicle through a half shaft.

2. The single planetary gear power holding type three-speed automatic transmission according to claim 1, characterized in that: One end of the input shaft is connected to the motor, and the other end of the input shaft extends into the transmission case. The planetary gear, the third-speed clutch and the planetary carrier brake are installed on the input shaft.

3. The single planetary gear power holding type three-speed automatic transmission according to claim 1, characterized in that: The planetary gear row also includes a sun gear and a plurality of planetary gears; the sun gear is fixedly connected to the end of the input shaft extending into the transmission case, the planet carrier is sleeved on the input shaft, the plurality of planetary gears are evenly distributed around the sun gear, the planet carrier is fixedly connected to the plurality of planetary gears, the ring gear is installed at the end of the ring gear brake, the plurality of planetary gears are meshed with the outside of the sun gear, and the plurality of planetary gears are meshed with the inside of the ring gear.

4. The single planetary gear power holding type three-speed automatic transmission according to claim 1, characterized in that: The ring gear brake and the planet carrier brake are both mounted on the inner wall of the transmission housing, the rotating part of the ring gear brake is relatively fixed to the ring gear, and the rotating part of the planet carrier brake is relatively fixed to the planet carrier.

5. The single planetary gear power holding type three-speed automatic transmission according to claim 1, characterized in that: One end of the planet carrier is also fixedly connected with a high and low gear driving gear, and the high and low gear driving gear is sleeved on the input shaft; the high and low gear driven gear is arranged on the left intermediate shaft, and the high and low gear driving gear is meshed with the high and low gear driven gear.

6. The single planetary gear power holding type three-speed automatic transmission according to claim 1, characterized in that: A second-gear input shaft is arranged at one end of the planetary gear row facing away from the input shaft, one end of the second-gear input shaft extends into the transmission case and is fitted with a second-gear driving gear, and the other end of the second-gear input shaft is mounted on the transmission case through a bearing; the second-gear driving gear is fixedly connected to the ring gear; The right intermediate shaft is provided with a second-gear driven gear, and the second-gear driving gear is connected to the second-gear driven gear through an idler gear transmission.

7. The single planetary gear power holding type three-speed automatic transmission according to claim 6, characterized in that: One end of the idler is fixedly connected to an idler shaft, and the other end of the idler shaft is mounted on the transmission housing through a bearing; The second-gear driving gear is constantly meshed with the idler gear, and the idler gear is constantly meshed with the second-gear driven gear at the same time.

8. The single planetary gear power holding type three-speed automatic transmission according to claim 1, characterized in that: The main reducer comprises a main reducer driving gear and a main reducer driven gear; the main reducer driving gear is mounted on the main intermediate shaft, and the main reducer driven gear is fixedly connected to the differential; The main reducer driving gear is meshed with the main reducer driven gear; The half shafts include a left half shaft and a right half shaft, and the two ends of the differential are respectively mounted on the left half shaft and the right half shaft.

9. The single planetary gear power holding type three-speed automatic transmission according to claim 1, characterized in that: The high and low gear clutch, the second gear clutch and the third gear clutch include electromagnetic clutches or mechanical clutches; The ring gear brake and the planet carrier brake include electromagnetic brakes or mechanical brakes.

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