A three-speed planetary gear transmission, an electric drive system, and an automobile

Abstract

This utility model relates to a three-speed planetary gear transmission, an electric drive system, and an automobile. The transmission includes: three shafts and half-shafts, the half-shafts being rotatable about their own axes; the three shafts are parallel to each other on one side of the half-shafts and are also rotatable about their own axes; an output gear is coaxially fixedly mounted on one end of each of the three shafts, and the output gear is connected to the half-shafts via a three-stage transmission assembly; a first-speed planetary gear is coaxially mounted on the other end of each of the three shafts, the first-speed planetary gear being able to idle around the three shafts or rotate with the three shafts; a second-speed gear and a third-speed gear are also coaxially mounted on the three shafts, the second-speed gear and the third-speed gear being able to idle around the three shafts or rotate with the three shafts respectively; the third-speed gear is connected to the sun gear of the first-speed planetary gear. The advantages of this utility model are its compact structure, reasonable design, and ability to freely switch between three different gears. The first gear drives the planetary gears in series, effectively increasing the speed ratio and providing torque output capability; the second and third gears disengage the planetary gear transmission, improving transmission efficiency.

Description

Technical Field

[0001] This utility model relates to the field of automobile manufacturing technology, specifically to a three-speed planetary gear transmission, an electric drive system, and an automobile. Background Technology

[0002] The rapid development of the automotive industry and the increasing demand for automobiles have led to a continuous rise in automobile production and ownership, which has exacerbated the energy and environmental issues that people are currently concerned about. As a result, electric vehicles have emerged.

[0003] Electric vehicles are vehicles that use onboard power sources to drive their wheels with electric motors and meet all road traffic and safety regulations. Because they have a relatively smaller environmental impact compared to traditional vehicles, their future prospects are widely viewed favorably.

[0004] Currently, the transmissions of electric vehicles in existing technologies typically use gears to achieve multi-stage power transmission, resulting in low transmission efficiency. Utility Model Content

[0005] This utility model addresses the technical problems existing in the prior art by providing a three-speed planetary gear transmission, an electric drive system, and an automobile.

[0006] The technical solution of this utility model to solve the above-mentioned technical problems is as follows: A three-speed planetary gear transmission includes: three shafts and half-shafts, wherein the half-shafts are rotatable about their own axis; the three shafts are distributed parallel to one side of the half-shafts and are rotatable about their own axis; an output gear is coaxially fixedly sleeved at one end of each of the three shafts, and the output gear is connected to the half-shafts through a three-stage transmission assembly. A first-gear planetary gear is coaxially mounted on the other end of the three shafts. The first-gear planetary gear can rotate freely around the three shafts or rotate together with the three shafts. A second-gear gear and a third-gear gear are also coaxially mounted on the three shafts. The second-gear gear and the third-gear gear are respectively located between the output gear and the first-gear planetary gear. They can rotate freely around the three shafts or rotate together with the three shafts. The third-gear gear is connected to the sun gear in the first-gear planetary gear.

[0007] The beneficial effects of this utility model are: The working process is as follows: (1) First gear transmission: The first gear planetary gear drives the three shafts to rotate together, the three shafts drive the output gear to rotate, and the output gear drives the half shaft to rotate together using the three-stage transmission assembly, thereby realizing the transmission and output of power; (2) Second gear transmission: The second gear drives the three shafts to rotate together, the three shafts drive the output gear to rotate, and the output gear drives the half shaft to rotate together using the three-stage transmission assembly, thereby realizing the transmission and output of power; (3) Three-speed transmission: The three-speed gear drives the three shafts to rotate together, the three shafts drive the output gear to rotate, and the output gear drives the half shaft to rotate together using the three-stage transmission assembly, thereby realizing the transmission and output of power.

[0008] This utility model has a compact structure and reasonable design, and can freely switch between three different gears. The first gear is driven by a series planetary gear, which effectively increases the speed ratio and provides torque output capability. In addition, the second and third gears disengage the planetary gear transmission, which improves the transmission efficiency.

[0009] Based on the above technical solution, the present invention can be further improved as follows.

[0010] Furthermore, a meshing sleeve A is also fitted on the three shafts. The meshing sleeve A is located between the second gear and the third gear. It can rotate together with the three shafts, and the meshing sleeve A can slide along the axial direction of the three shafts to mesh with the second gear or the third gear.

[0011] The advantages of adopting the above-mentioned further scheme are that the structure is simple and the design is reasonable. By using the meshing sleeve A to slide on the three shafts, the meshing sleeve A can mesh with the second gear or the third gear, thereby realizing the second gear or the third gear to rotate together with the three shafts, realizing the transmission of power. The transmission is convenient and the transmission efficiency is high.

[0012] Furthermore, the other end of the three shafts is coaxially fitted with a meshing sleeve B, which can rotate with the three shafts and slide along the axial direction of the three shafts to mesh with or disengage from the first-gear planetary gear.

[0013] The advantages of adopting the above-mentioned further scheme are that the structure is simple and the design is reasonable. By using the meshing sleeve B to slide on the three shafts, the meshing sleeve B can mesh with or disengage from the first-gear planetary gear, thereby realizing the first-gear planetary gear to rotate freely around the three shafts or rotate together with the three shafts, realizing the transmission of power. The transmission is convenient and the transmission efficiency is high.

[0014] Furthermore, the three-stage transmission assembly includes a three-stage gear and a differential, with the differential coaxially fixedly sleeved on the half-shaft; the three-stage gear is coaxially fixedly sleeved on the differential and meshes with the output gear.

[0015] The advantages of adopting the above-mentioned further scheme are that the structure is simple and the design is reasonable. The three shafts drive the output gear to rotate, the output gear drives the three-stage gear to rotate, and the three-stage gear drives the differential to rotate, thereby realizing the transmission of power. The transmission is convenient and the transmission efficiency is high.

[0016] Furthermore, the differential includes a housing that is fitted over the half-shaft and is connected to the half-shaft via a gear assembly.

[0017] The advantages of adopting the above-mentioned further scheme are that the structure is simple and the design is reasonable. The three-stage gear is assembled using the housing and the housing is assembled on the half shaft, which makes the assembly convenient and facilitates the transmission of power.

[0018] Furthermore, the gear assembly includes a ring gear and a bevel gear, with the ring gear coaxially fixedly sleeved on the half shaft; the bevel gear is installed inside the housing and meshes with the ring gear.

[0019] The advantages of adopting the above-mentioned further scheme are that the structure is simple and the design is reasonable. The three shafts drive the output gear to rotate, the output gear drives the three-stage gear to rotate, the three-stage gear drives the differential housing to rotate, the housing uses bevel gears to drive the ring gear to rotate, and the ring gear drives the half shaft to rotate, thereby realizing the transmission of power. The transmission is convenient and efficient.

[0020] This utility model also relates to an electric drive system, including a motor, a first shaft, a second shaft, and a three-speed planetary gear transmission as described above. The first shaft and the second shaft are respectively distributed parallel to each other on the side of the third shaft away from the half shaft, and each can rotate about its own axis. The second shaft is located between the first shaft and the third shaft, and the first shaft is connected to the second shaft through a primary transmission assembly. The second shaft meshes with any one of the first-gear planetary gear, the second-gear, and the third-gear via a two-stage transmission assembly; the motor is fixedly installed, with its drive end extending along the axial direction of the first shaft and fixedly connected to one end of the first shaft.

[0021] The beneficial effect of adopting the above-mentioned further solution is that the working process is as follows: the motor drives one shaft to rotate, the first shaft drives the second shaft to rotate through the first-stage transmission assembly, and the second shaft drives any one of the first-speed planetary gear, the second-speed gear, and the third-speed gear to rotate through the second-stage transmission assembly, thereby realizing the transmission of power. The specific transmission process is as follows: (1) First gear transmission: The first gear planetary gear drives the three shafts to rotate together, the three shafts drive the output gear to rotate, and the output gear drives the half shaft to rotate together using the three-stage transmission assembly, thereby realizing the transmission and output of power; (2) Second gear transmission: The second gear drives the three shafts to rotate together, the three shafts drive the output gear to rotate, and the output gear drives the half shaft to rotate together using the three-stage transmission assembly, thereby realizing the transmission and output of power; (3) Three-speed transmission: The three-speed gear drives the three shafts to rotate together, the three shafts drive the output gear to rotate, and the output gear drives the half shaft to rotate together using the three-stage transmission assembly, thereby realizing the transmission and output of power; In addition, this utility model also provides an electric drive system with a compact structure and reasonable design. It can freely switch between three different gears. The first gear is driven by a series planetary gear, which effectively increases the speed ratio and provides torque output capability. In addition, the second and third gears disengage the planetary gear transmission to improve transmission efficiency.

[0022] Furthermore, the primary transmission assembly includes a primary gear and a secondary gear. The primary gear is coaxially fixedly sleeved on the primary shaft; the secondary gear is coaxially fixedly sleeved on the secondary shaft and meshes with the primary gear.

[0023] The advantages of adopting the above-mentioned further scheme are that the structure is simple and the design is reasonable. During the rotation of the first shaft, the first gear on it drives the second gear to rotate, thereby driving the second shaft to rotate and realizing the transmission of power.

[0024] Furthermore, the secondary transmission assembly includes a secondary H-gear and a secondary L-gear. The secondary L-gear is coaxially fixedly sleeved on the second shaft and meshes with the second gear. The secondary H-gear is coaxially fixedly sleeved on the second shaft and can mesh with the third gear.

[0025] The advantages of adopting the above-mentioned further scheme are that the structure is simple and the design is reasonable. The two shafts use the second-stage H gear and the second-stage L gear to drive any one of the first-stage planetary gear, the second gear and the third gear to rotate, thereby realizing gear switching and power transmission.

[0026] This utility model also relates to an automobile, including the electric drive system described above.

[0027] The beneficial effect of adopting the above-mentioned further solution is that this utility model also provides an automobile with a compact structure and reasonable design, which can realize free switching of three different gears. The first gear is driven by a planetary gear in series, which effectively increases the speed ratio and provides torque output capability; in addition, the second and third gears disengage the planetary gear transmission, which improves the transmission efficiency. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the overall structure of this utility model; Figure 2 This is a diagram showing the first gear power transmission in this utility model; Figure 3 This is a diagram showing the power transmission in the second gear of this utility model; Figure 4 This is a diagram showing the three-speed power transmission in this utility model.

[0029] The attached diagram lists the components represented by each number as follows: 1. Three-shaft; 2. Half-shaft; 3. Output gear; 4. First-gear planetary gear; 5. Second-gear gear; 6. Third-gear gear; 7. Engaging sleeve A; 8. Engaging sleeve B; 9. Third-stage gear; 10. Housing; 11. Ring gear; 12. Bevel gear; 13. Motor; 14. First shaft; 15. Second shaft; 16. First-stage gear; 17. Second-stage gear; 18. Second-stage H-gear gear; 19. Second-stage L-gear gear. Detailed Implementation

[0030] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0031] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0032] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this technology based on the specific circumstances.

[0033] In the description of this application, spatial relation terms such as "below," "under," "below," "below," "above," "over," etc., are used herein to describe the relationship between one element or feature shown in the figures and other elements or features. It should be understood that, in addition to the orientation shown in the figures, spatial relation terms also include different orientations of the device in use and operation. For example, if the device in the figures is flipped, an element or feature described as "below" or "under" or "below" of other elements or features will be oriented "above" other elements or features. Therefore, the exemplary terms "below" and "under" can include both upper and lower orientations. Furthermore, the device may also include other orientations (e.g., rotated 90 degrees or other orientations), and the spatial descriptive terms used herein are interpreted accordingly.

[0034] In the description of this application, the term "for example" is used to mean "used as an example, illustration, or description." Any embodiment described as "for example" in this application is not necessarily to be construed as being more preferred or advantageous than other embodiments. The following description is provided to enable any person skilled in the art to implement and use the present invention. Details are set forth in the following description for purposes of explanation. It should be understood that those skilled in the art will recognize that the present invention can be implemented without using these specific details. In other instances, well-known structures and processes will not be described in detail to avoid obscuring the description of the present invention with unnecessary detail. Therefore, the present invention is not intended to be limited to the embodiments shown, but is consistent with the broadest scope of the principles and features disclosed in this application.

[0035] Example 1 like Figures 1 to 4 As shown, this embodiment provides a three-speed planetary gear transmission, including: a three-shaft 1 and a half-shaft 2, wherein the half-shaft 2 can rotate about its own axis; the three-shaft 1 is distributed parallel to one side of the half-shaft 2 and can rotate about its own axis; an output gear 3 is coaxially fixedly sleeved at one end of the three-shaft 1, and the output gear 3 is connected to the half-shaft 2 through a three-stage transmission assembly; A first-gear planetary gear 4 is coaxially mounted on the other end of the three-axis 1. The first-gear planetary gear 4 can rotate freely around the three-axis 1 or rotate together with the three-axis 1. A second-gear gear 5 and a third-gear gear 6 are also coaxially mounted on the three-axis 1. The second-gear gear 5 and the third-gear gear 6 are respectively located between the output gear 3 and the first-gear planetary gear 4. They can rotate freely around the three-axis 1 or rotate together with the three-axis 1. The third-gear gear 6 is connected to the sun gear in the first-gear planetary gear 4.

[0036] The working process is as follows: (1) First gear transmission: the first gear planetary gear 4 drives the three shafts 1 to rotate together, the three shafts 1 drive the output gear 3 to rotate, and the output gear 3 drives the half shaft 2 to rotate together using the three-stage transmission assembly, thereby realizing the transmission and output of power; (2) Second gear transmission: Second gear 5 drives the three shafts 1 to rotate together, the three shafts 1 drive the output gear 3 to rotate, and the output gear 3 drives the half shaft 2 to rotate together using the three-stage transmission assembly, thereby realizing the transmission and output of power; (3) Three-speed transmission: the three-speed gear 6 drives the three shafts 1 to rotate together, the three shafts 1 drive the output gear 3 to rotate, and the output gear 3 drives the half shaft 2 to rotate together using the three-stage transmission assembly, thereby realizing the transmission and output of power.

[0037] This embodiment has a compact structure and reasonable design, and can freely switch between three different gears. The first gear is driven by a series planetary gear, which effectively increases the speed ratio and provides torque output capability. In addition, the second and third gears disengage the planetary gear transmission, which improves transmission efficiency.

[0038] Example 2 Based on Embodiment 1, in this embodiment, a meshing sleeve A7 is also fitted on the three shafts 1. The meshing sleeve A7 is located between the second gear 5 and the third gear 6. It can rotate together with the three shafts 1, and the meshing sleeve A7 can slide along the axial direction of the three shafts 1 to mesh with the second gear 5 or the third gear 6.

[0039] The scheme has a simple structure and reasonable design. It utilizes the sliding of the meshing sleeve A7 on the three shafts 1 to make the meshing sleeve A7 mesh with the second gear 5 or the third gear 6, thereby realizing the rotation of the second gear 5 or the third gear 6 together with the three shafts 1, realizing the transmission of power. The transmission is convenient and has high efficiency.

[0040] Alternatively, a synchronizer can be used to replace the aforementioned engagement sleeve A7.

[0041] Example 3 Based on the above embodiments, in this embodiment, the other end of the three shafts 1 is also coaxially fitted with a meshing sleeve B8. The meshing sleeve B8 can rotate together with the three shafts 1, and it can slide along the axial direction of the three shafts 1 to mesh with or disengage from the first-gear planetary gear 4.

[0042] The scheme has a simple structure and reasonable design. It utilizes the sliding of the meshing sleeve B8 on the three shafts 1 to allow the meshing sleeve B8 to mesh with or disengage from the first-gear planetary gear 4. This enables the first-gear planetary gear 4 to rotate freely around the three shafts 1 or rotate together with the three shafts 1, thus realizing the transmission of power. The transmission is convenient and has high efficiency.

[0043] Alternatively, a synchronizer can be used to replace the aforementioned engagement sleeve B8.

[0044] Example 4 Based on the above embodiments, in this embodiment, the three-stage transmission assembly includes a three-stage gear 9 and a differential, the differential being coaxially fixedly sleeved on the half-shaft 2; the three-stage gear 9 is coaxially fixedly sleeved on the differential, and meshes with the output gear 3.

[0045] The scheme has a simple structure and reasonable design. The three shafts 1 drive the output gear 3 to rotate, the output gear 3 drives the three-stage gear 9 to rotate, and the three-stage gear 9 drives the differential to rotate, thereby realizing the transmission of power. The transmission is convenient and efficient.

[0046] Example 5 Based on Embodiment 4, in this embodiment, the differential includes a housing 10, which is sleeved on the half-shaft 2 and is connected to the half-shaft 2 via a gear assembly.

[0047] The scheme has a simple structure and reasonable design. It utilizes the housing 10 to assemble the three-stage gear 9 and the housing 10 to assemble the half shaft 2, which is convenient for assembly and facilitates power transmission.

[0048] Preferably, in this embodiment, the shell 10 is preferably a cylindrical shell structure.

[0049] Example 6 Based on Embodiment 5, in this embodiment, the gear assembly includes a ring gear 11 and a bevel gear 12. The ring gear 11 is coaxially fixedly sleeved on the half shaft 2; the bevel gear 12 is installed inside the housing 10 and meshes with the ring gear 11.

[0050] The scheme has a simple structure and reasonable design. The three shafts 1 drive the output gear 3 to rotate, the output gear 3 drives the three-stage gear 9 to rotate, the three-stage gear 9 drives the differential housing 10 to rotate, the housing 10 uses the bevel gear 12 to drive the ring gear 11 to rotate, and the ring gear 11 drives the half shaft 2 to rotate, thereby realizing the transmission of power. The transmission is convenient and has high efficiency.

[0051] Example 7 Based on the above embodiments, this embodiment also provides an electric drive system, including a motor 13, a first shaft 14, a second shaft 15, and a three-speed planetary gear transmission as described above. The first shaft 14 and the second shaft 15 are respectively distributed in parallel on the side of the third shaft 1 away from the half shaft 2, and each can rotate about its own axis. The second shaft 15 is located between the first shaft 14 and the third shaft 1, and the first shaft 14 is connected to the second shaft 15 through a primary transmission assembly. The second shaft 15 meshes with any one of the first-gear planetary gear 4, the second-gear gear 5, and the third-gear gear 6 through a two-stage transmission assembly; the motor 13 is fixedly installed, and its drive end extends along the axial direction of the first shaft 14 and is fixedly connected to one end of the first shaft 14.

[0052] The working process is as follows: Motor 13 drives shaft 14 to rotate, shaft 14 drives shaft 15 to rotate through primary transmission assembly, and shaft 15 drives any one of the first-gear planetary gear 4, second-gear gear 5 and third-gear gear 6 to rotate through secondary transmission assembly, thereby realizing the transmission of power. (1) First gear transmission: The first gear planetary gear 4 drives the three shafts 1 to rotate together, the three shafts 1 drive the output gear 3 to rotate, and the output gear 3 drives the half shaft 2 to rotate together using the three-stage transmission assembly, thereby realizing the transmission and output of power; (2) Second gear transmission: Second gear 5 drives the three shafts 1 to rotate together, the three shafts 1 drive the output gear 3 to rotate, and the output gear 3 drives the half shaft 2 to rotate together using the three-stage transmission assembly, thereby realizing the transmission and output of power; (3) Three-speed transmission: The three-speed gear 6 drives the three shafts 1 to rotate together, the three shafts 1 drive the output gear 3 to rotate, and the output gear 3 drives the half shaft 2 to rotate together using the three-stage transmission assembly, thereby realizing the transmission and output of power; In addition, this embodiment also provides an electric drive system with a compact structure and reasonable design, which can realize free switching of three different gears. The first gear is driven by a series planetary gear, which effectively increases the speed ratio and provides torque output capability; in addition, the second and third gears disengage the planetary gear transmission to improve transmission efficiency.

[0053] Example 8 Based on Embodiment 7, in this embodiment, the primary transmission assembly includes a primary gear 16 and a secondary gear 17. The primary gear 16 is coaxially fixedly sleeved on the primary shaft 14; the secondary gear 17 is coaxially fixedly sleeved on the secondary shaft 15 and meshes with the primary gear 16.

[0054] The scheme has a simple structure and reasonable design. During the rotation of the first shaft 14, the first gear 16 drives the second gear 17 to rotate, thereby driving the second shaft 15 to rotate, thus realizing the transmission of power.

[0055] Example 9 Based on any one of Embodiments 7 to 8, in this embodiment, the secondary transmission assembly includes a secondary H gear 18 and a secondary L gear 19. The secondary L gear 19 is coaxially fixedly sleeved on the secondary shaft 15 and meshes with the secondary gear 5. The secondary H gear 18 is coaxially fixedly sleeved on the secondary shaft 15 and can mesh with the third gear 6.

[0056] The scheme has a simple structure and reasonable design. The second shaft 15 uses the second-stage H gear 18 and the second-stage L gear 19 to drive any one of the first-stage planetary gear 4, the second-stage gear 5 and the third-stage gear 6 to rotate, thereby realizing gear switching and power transmission.

[0057] Example 10 Based on the above embodiments, this embodiment also provides an automobile, including the electric drive system described above.

[0058] This embodiment also provides a car with a compact structure and reasonable design, which can freely switch between three different gears. The first gear is driven by a planetary gear in series, which effectively increases the speed ratio and provides torque output capability. In addition, the second and third gears disengage the planetary gear transmission to improve transmission efficiency.

[0059] This utility model provides a three-speed planetary gear transmission, an electric drive system, and an automobile, the working modes of which are as follows: First, motor 13 drives shaft 14 to rotate. Shaft 14 then drives shaft 15 to rotate via a primary transmission assembly. Shaft 15, in turn, drives any one of the following gears—first-gear planetary gear 4, second-gear gear 5, and third-gear gear 6—via a secondary transmission assembly, thus transmitting power. The specific transmission process is as follows: (1) First gear transmission: Engaging sleeve A7 is in the middle position (neutral), engagement sleeve B8 is in the engaged position, and power is transmitted through first gear 16 and second gear 17 --> second gear H gear 18 --> first gear planetary gear 4 --> three shaft 1 --> output gear 3 --> differential --> half shaft 2 (refer to) Figure 2 ); (2) Second gear transmission: Engaging sleeve A7 is in the left position (engaged with second gear 5), engagement sleeve B8 is in the disengaged position (neutral), power is output through first gear 16 and second gear 17 --> second gear L gear 19 --> three shaft 1 --> output gear 3 --> differential --> half shaft 2 (refer to) Figure 3 ); (3) Three-speed transmission: Engaging sleeve A7 is in the right position (engaged with third gear 6), engagement sleeve B8 is in the disengaged position (neutral), power is output through first-stage gear 16 and second-stage gear 17 --> second-stage H-gear gear 18 --> three-shaft 1 --> output gear 3 --> differential --> half-shaft 2 (refer to) Figure 4 ).

[0060] The arrows in the attached diagram merely indicate the path of power transmission and have no other substantial meaning.

[0061] The advantages of this utility model are as follows: 1. The first gear transmission uses a series planetary gear, which effectively increases the speed ratio and provides torque output capability; 2. The 2nd and 3rd gears disengage the planetary gear transmission and adopt cylindrical gear transmission to improve transmission efficiency.

[0062] While embodiments or examples of this disclosure have been described with reference to the accompanying drawings, it should be understood that the above embodiments are merely exemplary embodiments or examples, and the scope of this utility model is not limited by these embodiments or examples, but only by the granted claims and their equivalents. Various elements in the embodiments or examples may be omitted or replaced by their equivalents. Furthermore, the steps may be performed in a different order than that described in this disclosure. Further, various elements in the embodiments or examples may be combined in various ways. Importantly, as the technology evolves, many elements described herein can be replaced by equivalents that appear after this disclosure.

Claims

1. A three-speed planetary gear transmission, characterized in that, include: The three shafts (1) and half shafts (2) are provided. The half shafts (2) can rotate around their own axis. The three shafts (1) are distributed parallel to one side of the half shafts (2) and can rotate around their own axis. One end of the three shafts (1) is coaxially fixedly fitted with an output gear (3). The output gear (3) is connected to the half shafts (2) through a three-stage transmission assembly. The other end of the three shafts (1) is coaxially fitted with a first-gear planetary gear (4), which can rotate freely around the three shafts (1) or rotate together with the three shafts (1); a second-gear gear (5) and a third-gear gear (6) are also coaxially fitted on the three shafts (1), which are located between the output gear (3) and the first-gear planetary gear (4), respectively, and can rotate freely around the three shafts (1) or rotate together with the three shafts (1); the third-gear gear (6) is connected to the sun gear in the first-gear planetary gear (4).

2. The three-speed planetary gear transmission according to claim 1, characterized in that, The three shafts (1) are also fitted with a meshing sleeve A (7), which is located between the second gear (5) and the third gear (6). It can rotate together with the three shafts (1), and the meshing sleeve A (7) can slide along the axial direction of the three shafts (1) to mesh with the second gear (5) or the third gear (6).

3. The three-speed planetary gear transmission according to claim 1, characterized in that, The other end of the three shafts (1) is also coaxially fitted with a meshing sleeve B (8). The meshing sleeve B (8) can rotate together with the three shafts (1) and can slide along the axial direction of the three shafts (1) to mesh or disengage with the first-gear planetary gear (4).

4. The three-speed planetary gear transmission according to any one of claims 1-3, characterized in that, The three-stage transmission assembly includes a three-stage gear (9) and a differential. The differential is coaxially fixedly sleeved on the half-shaft (2). The three-stage gear (9) is coaxially fixedly sleeved on the differential and meshes with the output gear (3).

5. The three-speed planetary gear transmission according to claim 4, characterized in that, The differential includes a housing (10) which is fitted over the half-shaft (2) and is connected to the half-shaft (2) via a gear assembly.

6. The three-speed planetary gear transmission according to claim 5, characterized in that, The gear assembly includes a ring gear (11) and a bevel gear (12). The ring gear (11) is coaxially fixedly sleeved on the half shaft (2). The bevel gear (12) is installed in the housing (10) and meshes with the ring gear (11).

7. An electric drive system, characterized in that, The system includes a motor (13), a primary shaft (14), a secondary shaft (15), and a three-speed planetary gear transmission as described in any one of claims 1-6. The primary shaft (14) and the secondary shaft (15) are respectively distributed parallel to each other on the side of the secondary shaft (1) away from the half shaft (2), and each can rotate about its own axis. The secondary shaft (15) is located between the primary shaft (14) and the secondary shaft (1), and the primary shaft (14) is connected to the secondary shaft (15) through a primary transmission assembly. The second shaft (15) meshes with any one of the first-gear planetary gear (4), the second-gear gear (5) and the third-gear gear (6) through a two-stage transmission assembly; the motor (13) is fixedly installed, and its driving end extends along the axial direction of the first shaft (14) and is fixedly connected to one end of the first shaft (14).

8. The electric drive system according to claim 7, characterized in that, The primary transmission assembly includes a primary gear (16) and a secondary gear (17). The primary gear (16) is coaxially fixedly sleeved on the primary shaft (14); the secondary gear (17) is coaxially fixedly sleeved on the secondary shaft (15) and meshes with the primary gear (16).

9. The electric drive system according to claim 7, characterized in that, The secondary transmission assembly includes a secondary H gear (18) and a secondary L gear (19). The secondary L gear (19) is coaxially fixedly sleeved on the second shaft (15) and meshes with the second gear (5). The secondary H gear (18) is coaxially fixedly sleeved on the second shaft (15) and can mesh with the third gear (6).

10. A car, characterized in that, Includes the electric drive system as described in any one of claims 7-9.

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