Gear shifting assembly

Abstract

The invention relates to a gear shifting assembly for a gearbox, which comprises a shifting fork shaft, a gear shifting assembly, a gear shifting assembly and a gear shifting assembly, and is characterized in that the shifting fork shaft is fixedly mounted on a gearbox shell; the shifting fork is axially and movably arranged on the shifting fork shaft in a sleeving manner, and the shifting fork is provided with a plurality of different shifting fork positions relative to the shifting fork shaft in the axial direction; the lead screw mechanism is installed on the gear shifting fork and can drive the gear shifting fork to move in the axial direction; and the locking mechanism is arranged between the shifting fork and the shifting fork shaft, and the locking mechanism is configured to allow the shifting fork to be switched among a plurality of different shifting fork positions and allow the shifting fork to be locked at each shifting fork position. According to the gear shifting assembly, the adverse effect of unexpected axial force generated in the power transmission period on gear shifting operation can be effectively reduced, and meanwhile enough axial holding force can be provided so that the gear shifting fork can be stably locked at each shifting fork position.

Description

Technical Field

[0001] The present invention relates to the technical field of gearboxes, and in particular to a gear shift assembly for a gearbox. Background Art

[0002] Generally speaking, a transmission is located between the engine and the wheels, transferring engine power to the wheels to propel the vehicle. Therefore, the transmission's purpose is to vary torque and vehicle speed by changing the gear ratio to meet the vehicle's driving needs under various road conditions. To achieve this, transmissions often utilize gears of varying sizes to change gear ratios, and power transfer between gears is achieved by shift forks that activate dog clutches or synchronizers.

[0003] Existing technologies typically use a motor and a lead screw mechanism to drive the shift fork. The lead screw mechanism includes a screw and a nut that fits over the screw and meshes with it. The screw is connected to the motor, and the nut is connected to the shift fork. When the motor rotates the screw, the screw drives the nut axially, which in turn pushes the shift fork axially, thereby achieving gear shifting in the transmission.

[0004] However, when the synchronizer / dog clutch engages, causing the gears to transmit torque, the axial force exerted on the gears causes axial movement of the gear shaft on which the gears are mounted in the transmission. This axial movement, in turn, pushes the shift fork, which is dynamically connected to the gear shaft, in the axial direction. For some less precise lead screw mechanisms, since the nut remains against the shift fork during each shift operation, there is no axial clearance between the nut and the shift fork. Therefore, when the shift fork is subjected to axial force, it directly acts on the nut, causing the lead screw mechanism to self-lock. This prevents the axial force applied to the lead screw mechanism from being released, preventing the nut from moving axially and the screw from rotating further, thus preventing the shift fork from shifting. Furthermore, the axial force exerted on the shift fork whenever the transmission transmits torque reduces its durability, shortens its service life, and may cause abnormal wear of the plastic foot pads on the shift fork. Summary of the Invention

[0005] To overcome the above problems, the present invention proposes a shift assembly that can effectively reduce the adverse effects of unexpected axial forces generated during power transmission on the shifting operation, while providing sufficient axial retaining force to stably lock the shift fork in each fork position.

[0006] According to an embodiment of the present invention, a shift assembly for a transmission is proposed, comprising: a shift fork shaft fixedly mounted on a transmission housing; a shift fork axially movably sleeved on the shift fork shaft, wherein the shift fork has a plurality of different fork positions relative to the shift fork shaft in the axial direction; a screw mechanism mounted on the shift fork and capable of driving the shift fork to move in the axial direction; and a locking mechanism disposed between the shift fork and the shift fork shaft, wherein the locking mechanism is configured to allow the shift fork to switch between the plurality of different fork positions and to lock the shift fork at each fork position.

[0007] In a preferred embodiment of the present invention, the shift fork includes a mounting portion for mounting the screw mechanism, the screw mechanism includes a screw rod and a nut sleeved on the screw rod and movable axially relative to the screw rod, the screw rod is rotatably mounted on the mounting portion, and the nut is mounted in an internal space defined by the mounting portion, so that when the nut moves in the axial direction, the nut can push the shift fork to move in the axial direction through the mounting portion.

[0008] In a preferred embodiment of the present invention, the mounting portion has a first stop portion and a second stop portion arranged opposite to each other in the axial direction, so that when the nut moves relative to the screw in the axial direction, the nut can abut against the first stop portion or the second stop portion, thereby driving the shift fork to move in the axial direction and switch between the multiple different fork positions.

[0009] In a preferred embodiment of the present invention, the nut has a first end and a second end arranged opposite to each other in the axial direction. When the shift fork is located at each fork position, a first gap is formed between the first end of the nut and the first stop portion of the mounting portion, and a second gap is formed between the second end of the nut and the second stop portion of the mounting portion.

[0010] In a preferred embodiment of the present invention, the locking mechanism includes a plurality of locking grooves provided on the fork shaft and a locking device fixedly connected to the shift fork, the plurality of locking grooves corresponding to a plurality of different fork positions of the shift fork, and the locking device is configured such that when the shift fork moves in an axial direction relative to the fork shaft, its free end can slide into or out of each locking groove to switch between the plurality of locking grooves.

[0011] In a preferred embodiment of the present invention, the locking device includes a shell fixedly connected to the shift fork and having a hollow cavity, a steel ball embedded in the shell and capable of protruding from the open end of the shell to abut against the locking groove, and a spring accommodated in the hollow cavity of the shell to elastically support the steel ball.

[0012] In a preferred embodiment of the present invention, the locking device further comprises a spring seat accommodated in the hollow cavity of the housing, wherein the spring seat is sandwiched between the spring and the steel ball for supporting the spring.

[0013] In a preferred embodiment of the present invention, the plurality of locking grooves are continuously arranged on the fork shaft along the axial direction, each locking groove has an arcuate surface, and the radial depth of each locking groove gradually increases from its axial sides toward the axial center.

[0014] In a preferred embodiment of the present invention, the shift fork shaft includes a first end and a second end opposite to each other in the axial direction, and an elastic buffer is provided between at least one of the first end and the second end and the transmission housing.

[0015] In a preferred embodiment of the present invention, the elastic buffer is a spring that is retractable in the axial direction, and the spring is sandwiched between the shift fork shaft and the gearbox housing in the axial direction.

[0016] Therefore, according to an embodiment of the present invention, by leaving a gap in the axial direction between the nut and the shift fork at each fork position, it is possible to effectively prevent the unexpected axial force generated during power transmission from being applied to the screw mechanism through the shift fork, thereby causing the screw mechanism to self-lock, thereby effectively preventing the self-locking behavior of the screw mechanism from affecting the implementation of the shifting operation. At the same time, by utilizing the mutual cooperation between the locking groove and the locking device, sufficient axial retaining force can be provided to the shift fork, so that the shift fork can be stably locked at each fork position. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Features, advantages, and technical effects of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings.

[0018] Figure 1 A schematic cross-sectional view of a shift fork assembly according to an embodiment of the present invention is shown.

[0019] Figure 2 A schematic cross-sectional view of a shift fork assembly according to an embodiment of the present invention during a shifting process is shown.

[0020] Figure 3 A schematic cross-sectional view of a shift fork assembly according to an embodiment of the present invention after a gear shift is completed is shown.

[0021] However, the drawings are not necessarily drawn according to the actual scale. DETAILED DESCRIPTION

[0022] The following embodiments of the present invention are further described in detail with reference to the accompanying drawings and examples, wherein the same or similar components in the drawings are designated by the same reference numerals. The following detailed description of the embodiments and the accompanying drawings are intended to illustrate the principles of the present invention and are not intended to limit the scope of the invention. That is, the present invention is not limited to the described embodiments.

[0023] In the description of this application, unless otherwise specified, the terms "upper," "lower," "inner," "outer," etc., indicating directions or positional relationships, are intended solely to facilitate the description of this application and simplify the description. They are not intended to indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limiting this application. Furthermore, the terms "first" and "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The directional terms appearing in the following description refer to the directions shown in the drawings and do not limit the specific structure of this application.

[0024] In the description of the present invention, it should also be noted that, unless otherwise expressly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium. In addition, it should be understood that the term "torque-resistant connection" refers to the connection between two elements in a manner that does not rotate relative to each other, so that torque can be transmitted between the two elements, and the torque-resistant connection can be achieved through interference fit, bolt connection, gear connection, welding, spline connection, adhesive bonding, etc., or by forming the two mentioned elements into one piece. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0025] In order to better understand the present invention, Figures 1 to 3 The shift assembly according to an embodiment of the present invention is described in detail. The shift assembly according to the present invention can be used in a gearbox to provide different gears and change the transmission ratio of the gearbox. Figures 1 to 3 As shown, the shift assembly includes a shift fork shaft 10, a shift fork 20, a screw mechanism 30, and a locking mechanism 40. The axial direction is indicated by D1 and the radial direction is indicated by D2.

[0026] The shift fork shaft 10 extends in the axial direction D1 and is fixedly mounted on the transmission housing. That is, the shift fork shaft 10 is non-rotatable relative to the transmission housing and is non-movable in the axial direction D1.

[0027] The shift fork 20 is axially movably mounted on the fork shaft 10. In the axial direction D1, the shift fork 20 has multiple different fork positions relative to the fork shaft 10. Different fork positions correspond to different gear positions of the transmission. While three fork positions are shown herein, it should be understood that the present invention is not limited to three fork positions.

[0028] The screw mechanism 30 is mounted on the shift fork 20 and is capable of driving the shift fork 20 to move in the axial direction D1. Specifically, the shift fork 20 includes a mounting portion 21 for mounting the screw mechanism 30. The mounting portion 21 passes through the shift fork 20 in the axial direction D1 and defines an internal space. The screw mechanism 30 includes a screw rod 31 and a nut 32, wherein the screw rod 31 is rotatably mounted on the mounting portion 21, and one end of the screw rod 31 is connected to a motor (not shown in the figure). The nut 32 is axially movably sleeved on the screw rod 31 and is accommodated in the internal space defined by the mounting portion 21. Therefore, when the motor drives the screw rod 31 to rotate, the screw rod 31 can drive the nut 32 to move relative to the screw rod 31 in the axial direction D1 in the internal space. When the nut 32 moves in the axial direction D1, the nut 32 can push the shift fork 20 to move in the axial direction D1 through the mounting portion 21. That is, the screw mechanism 30 can convert the rotational motion of the motor into the axial motion of the nut 32 , thereby enabling the axial movement of the shift fork 20 to switch between a plurality of different fork positions.

[0029] The locking mechanism 40 is provided between the shift fork 20 and the fork shaft 10 . The locking mechanism 40 is configured to allow the shift fork 20 to be switched between a plurality of different fork positions. The locking mechanism 40 is also configured to provide sufficient axial holding force for the shifting device and lock the shift fork 20 at each fork position.

[0030] In some embodiments, the mounting portion 21 has a first stop portion 22 and a second stop portion 23 that are arranged relative to each other along the axial direction D1, so that when the nut 32 moves relative to the screw rod 31 along the axial direction D1, the nut 32 can abut against the first stop portion 22 or the second stop portion 23, thereby driving the shift fork 20 to move along the axial direction D1 and switch between multiple different fork positions.

[0031] For example, the nut 32 has a first end and a second end disposed opposite each other along the axial direction D1. The first stop 22 and the second stop 23 are disposed at the first and second ends of the nut 32, respectively, along the axial direction D1. The first stop 22 and the second stop 23 each extend from the mounting portion 21 along the radial direction D2 toward the screw 31. The first stop 22 may be integrally formed with the mounting portion 21. The second stop 23 may be a retaining spring fixedly engaged with the inner circumferential surface of the mounting portion 21. Therefore, when the screw 31 drives the nut 32 to move leftward along the axial direction D1, one axial end of the nut 32 abuts the first stop 22, thereby pushing the shift fork 20 leftward along the axial direction D1. When the screw 31 drives the nut 32 to move rightward along the axial direction D1, the other axial end of the nut 32 abuts the second stop 23, thereby pushing the shift fork 20 rightward along the axial direction D1.

[0032] In some embodiments, when the shift fork 20 is in each fork position, a first gap 22a is formed between the first end of the nut 32 and the first stop 22 of the mounting portion 21, and a second gap 22b is formed between the second end of the nut 32 and the second stop 23 of the mounting portion 21. In other words, both the first gap 22a and the second gap 22b are formed within the interior space defined by the mounting portion 21. The first gap 22a and the second gap 22b can be the same or different. Furthermore, the sizes of the first gap 22a and the second gap 22b vary over time as the shift fork 20 switches between different fork positions.

[0033] Therefore, according to the embodiment of the present invention, when the shift fork 20 is in each fork position, the opposite ends of the nut 32 do not abut the shift fork 20. In other words, when the shift fork 20 is in each fork position, the nut 32 and the shift fork 20 are separated from each other in the axial direction D1. Therefore, even if the shift fork 20 is slightly moved axially by the axial force transmitted by the gears, this slight axial movement will not act on the nut 32 and cause the screw mechanism 30 to self-lock. Therefore, the occurrence of shifting problems caused by the self-locking behavior of the screw mechanism 30 can be prevented.

[0034] In some embodiments, the locking mechanism 40 includes a plurality of locking grooves 41 disposed on the shift fork shaft 10 and a locking device 42 fixedly connected to the shift fork 20. The plurality of locking grooves 41 correspond to a plurality of different fork positions of the shift fork 20. The locking device 42 is configured such that, as the shift fork 20 moves relative to the shift fork shaft 10 in the axial direction D1, its free end can slide into or out of each locking groove 41 to shift between the plurality of locking grooves 41. Therefore, as the locking device 42 slides between the plurality of locking grooves 41, the shift fork 20 can be shifted between a plurality of different fork positions, thereby enabling shifting between different gears of the transmission. Furthermore, when the shift fork 20 is in each fork position, the provision of the locking grooves 41 provides an axial retaining function for the locking mechanism 40, thereby providing sufficient axial retaining force for the shift fork 20 to stably lock the shift fork 20 in each fork position.

[0035] Figures 1 to 3 The shift fork shaft 10 is shown with three locking grooves 41 along the axial direction D1. The three locking grooves 41 correspond to the three shift fork positions of the shift fork 20 and the three gear positions of the transmission. However, it should be understood that the present invention is not limited to this, and the number of locking grooves 41 can be more or less than three.

[0036] In some embodiments, multiple locking grooves 41 are continuously arranged on the fork shaft 10 along the axial direction D1, so that the locking device 42 can achieve switching between multiple different gears by moving a relatively short distance along the axial direction D1, thereby making the structure of the entire shift assembly more compact.

[0037] In some embodiments, each locking groove 41 has an arcuate surface, and the radial depth of each locking groove 41 gradually increases from the axial sides toward the axial center. In other words, the depth of each locking groove 41 is smaller on its axial sides and larger at its axial center. Therefore, when the shift fork 20 is in each fork position, due to the larger radial depth at the center of the locking groove 41, even if the shift fork 20 is subjected to axial external forces caused by gear transmission in the transmission, the locking device 42 will not easily slide out of the locking groove 41. Therefore, the arcuate locking groove 41 can provide sufficient axial retention force for the shift fork 20 at each fork position, thereby preventing the shift fork 20 from undesirably shifting between adjacent fork positions.

[0038] In some embodiments, the locking device 42 according to the present invention includes a housing 421, a steel ball 422, and a spring 423. The housing 421 is fixedly connected to the shift fork 20 and has a hollow cavity. For example, the housing 421 has a cylindrical shape with one end closed and the other end open, wherein the open end of the housing 421 faces the shift fork shaft 10. The steel ball 422 is embedded in the housing 421 and can protrude from the open end of the housing 421 to abut against the locking groove 41 of the shift fork shaft 10. The spring 423 is accommodated in the hollow cavity of the housing 421 to elastically support the steel ball 422. The spring 423 is configured as a cylindrical coil spring 423, for example. The spring 423 can undergo elastic deformation, so that when the shift fork 20 moves axially relative to the shift fork shaft 10, the steel ball 422 can slide into or out of the locking groove 41, thereby allowing the shift fork 20 to switch between different shift fork gears. At the same time, due to the elastic deformation performance of the spring 423, the steel ball 422 can always be against the locking groove surface of the locking groove 41 during the gear switching process of different shift forks 20, so that the gear shifting process can be smoother.

[0039] In some embodiments, the locking device 42 further includes a spring seat 424 housed within the hollow cavity of the housing 421. The spring seat 424 is sandwiched between the spring 423 and the steel ball 422 and is configured to support the spring 423, thereby allowing the spring 423 to elastically support the steel ball 422 via the spring seat 424. The spring seat 424 reduces wear on the spring 423 caused by the rolling of the steel ball 422 and reduces friction between the steel ball 422 and the spring 423, allowing the steel ball 422 to roll more smoothly on the locking groove 41, thereby extending the service life of the spring 423. The spring seat 424 includes a head and a rod connected to the head. The head is closer to the steel ball 422 than the rod, so that the steel ball 422 abuts the head of the spring seat 424. The spring 423 is sleeved onto the outer circumferential surface of the rod, thereby supporting the spring 423. Therefore, the spring seat 424 can be used as a guiding element for the spring 423 , so that one end of the spring 423 abuts against the head of the spring seat 424 and the other end abuts against the inner side of the housing 421 .

[0040] Next, we will combine Figures 2 to 3 To describe the shifting operation of the shift mechanism. Figures 2 to 3 Three locking groove positions are shown, which are referred to herein as a first locking groove position 41a located on the left and corresponding to the first fork position, a second locking groove position 41b located in the middle and corresponding to the second fork position, and a third locking groove position 41c located on the right and corresponding to the third fork position. Figure 2As shown, when the shift fork 20 is in the second fork position, that is, when the locking device 42 is in the second locking groove position 41b, a first gap 22a is left between the first end of the nut 32 and the first stop portion 22 of the mounting portion 21, and a second gap 22b is left between the second end of the nut 32 and the second stop portion 23 of the mounting portion 21.

[0041] When the shift fork 20 switches from the second fork position to the third fork position, the motor first rotates in a predetermined direction, thereby driving the screw 31 to rotate. The screw 31 then drives the nut 32 to move rightward until the second gap 22b between the second end of the nut 32 and the second stop 23 is zero. At this time, the first gap 22a between the first end of the nut 32 and the first stop 22 is maximized, and the shift fork 20 remains in the second fork position. Subsequently, the motor continues to drive the screw 31 to rotate, and the nut 32 continues to move rightward. Since the second gap 22b is zero, the nut 32 pushes the shift fork 20 to move rightward through the second stop 23, and the shift fork 20 pushes the synchronizer / dog clutch to engage until it reaches the end stop of the synchronizer sleeve. At this time, the locking device 42 reaches the third locking groove position 41c, and the shift fork 20 is in the third fork position. In this state, the first gap 22a between the first end of the nut 32 and the first stop 22 is also maximized.

[0042] When the shifting action is completed, Figure 3 As shown, when the shift fork 20 is in the third fork position, that is, when the locking device 42 is in the third locking groove position 41c, the motor can be rotated by a certain angle in a direction opposite to the predetermined direction, so that the nut 32 moves to the left by a predetermined distance. The predetermined distance leaves a first gap 22a between the first end of the nut 32 and the first stop portion 22 of the mounting portion 21, and a second gap 22b between the second end of the nut 32 and the second stop portion 23 of the mounting portion 21.

[0043] That is, at each fork position, the nut 32 and the shift fork 20 are always separated from each other in the axial direction D1. Therefore, even when the shift fork is slightly displaced axially by the axial force generated by gear transmission, this slight axial movement will not affect the nut 32 and cause the screw mechanism 30 to self-lock, thereby preventing the self-locking behavior of the screw mechanism 30 from causing unsmooth shifting. Furthermore, due to the interaction between the locking device 42 and the locking groove 41, even if the shift fork 20 is subjected to external axial forces caused by gear transmission in the transmission, the locking device 42 will not easily slide out of the locking groove 41, thereby preventing the shift fork 20 from shifting between adjacent fork positions and causing undesirable shifting.

[0044] In some embodiments, the shift fork shaft 10 includes a first end and a second end that are opposed to each other along the axial direction D1. An elastic buffer 50 may be disposed between at least one of the first end and the second end and the transmission housing 421. In other words, the elastic buffer 50 is disposed between the shift fork shaft 10 and the transmission housing along the axial direction D1. Thus, the elastic buffer 50 can eliminate axial play between the shift fork shaft 10 and the transmission housing caused by installation tolerances and / or gear transmission, thereby preventing axial movement of the shift fork shaft 10 during power transmission, thereby ensuring accurate and stable power transmission.

[0045] For example, the elastic buffer 50 can be a spring 423 that is retractable along the axial direction D1. The spring 423 is sandwiched between the fork shaft 10 and the transmission housing along the axial direction D1, so that one end of the spring 423 abuts against the fork shaft 10 and the other end abuts against the transmission housing. Figures 1 to 3 As shown, at least one of the first and second ends of the shift fork shaft 10 is formed with an axially extending opening, into which a spring 423 can be accommodated. When in an undeformed state, the spring 423 is configured to protrude from the axial end surface of the shift fork shaft 10. Thus, the elasticity of the spring 423 can eliminate axial play between the shift fork shaft 10 and the transmission housing. However, it should be understood that the present invention is not limited to this embodiment; the elastic spring 423 may alternatively be a cushion made of a compressible material (e.g., rubber or plastic).

[0046] For example, the number of elastic buffer members 50 may be one, and the elastic buffer member 50 may be disposed between either the first end or the second end of the shift fork shaft 10 and the transmission housing. However, it should be understood that the present invention is not limited to this. The number of elastic buffer members 50 may be two, and the two elastic buffer members 50 may be disposed between the first end of the shift fork shaft 10 and the transmission housing, and between the second end of the shift fork shaft 10 and the transmission housing, respectively.

[0047] Thus, according to the embodiment of the present invention, after the shift assembly is assembled, during the shifting process or power transmission, the shift fork shaft 10 will compress the elastic buffer 50, causing elastic deformation. Utilizing the elastic deformation characteristics of the elastic buffer 50, the shift fork shaft 10 and the transmission housing are always tightly and seamlessly fitted. Therefore, the elastic buffer 50 can eliminate axial play between the shift fork shaft 10 and the transmission housing caused by installation tolerances and / or power transmission, preventing axial movement of the shift fork shaft 10 during power transmission, thereby ensuring accurate and stable power transmission.

[0048] Although the present invention has been described with reference to preferred embodiments, various modifications may be made thereto and equivalents may be substituted for elements thereof without departing from the scope of the present invention. In particular, the various technical features described in the various embodiments may be combined in any manner as long as there are no structural conflicts. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions within the scope of the claims.

Claims

1. A shift assembly for a transmission, comprising: A shift fork shaft (10) fixedly mounted on the gearbox housing; A shift fork (20) is axially movably sleeved on the fork shaft (10), wherein in the axial direction, the shift fork (20) has a plurality of different fork positions relative to the fork shaft (10); a screw mechanism (30) mounted on the shift fork (20) and capable of driving the shift fork (20) to move in an axial direction; as well as A locking mechanism (40) is provided between the shift fork (20) and the fork shaft (10), the locking mechanism (40) being configured to allow the shift fork (20) to be switched between the plurality of different fork positions and to allow the shift fork (20) to be locked at each fork position.

2. The shift assembly according to claim 1, wherein: The shift fork (20) includes a mounting portion (21) for mounting the screw mechanism (30), the screw mechanism (30) includes a screw rod (31) and a nut (32) sleeved on the screw rod (31) and axially movable relative to the screw rod (31), the screw rod (31) being rotatably mounted on the mounting portion (21), and the nut (32) being mounted in an internal space defined by the mounting portion (21), so that when the nut (32) moves in the axial direction, the nut (32) can push the shift fork (20) to move in the axial direction through the mounting portion (21).

3. The shift assembly according to claim 2, wherein: The mounting portion (21) has a first stop portion (22) and a second stop portion (23) arranged opposite to each other in the axial direction, so that when the nut (32) moves relative to the screw rod (31) in the axial direction, the nut (32) can abut against the first stop portion (22) or the second stop portion (23), thereby driving the shift fork (20) to move in the axial direction and switch between the multiple different fork positions.

4. The shift assembly according to claim 3, wherein: The nut (32) has a first end and a second end that are arranged opposite to each other in the axial direction. When the shift fork (20) is located at each fork position, a first gap (22a) is formed between the first end of the nut (32) and the first stopper (22) of the mounting portion (21), and a second gap (22b) is formed between the second end of the nut (32) and the second stopper (23) of the mounting portion (21).

5. The shift assembly according to claim 1, wherein: The locking mechanism (40) comprises a plurality of locking grooves (41) provided on the fork shaft (10) and a locking device (42) fixedly connected to the shift fork (20), wherein the plurality of locking grooves (41) correspond to a plurality of different fork positions of the shift fork (20), and the locking device (42) is configured such that when the shift fork (20) moves in an axial direction relative to the fork shaft (10), its free end can slide into or out of each locking groove (41) to switch between the plurality of locking grooves (41).

6. The shift assembly according to claim 5, wherein: The locking device (42) includes a housing (421) fixedly connected to the shift fork (20) and having a hollow cavity, a steel ball (422) embedded in the housing (421) and capable of protruding from an open end of the housing (421) to abut against the locking groove (41), and a spring (423) accommodated in the hollow cavity of the housing (421) to elastically support the steel ball.

7. The shift assembly according to claim 6, wherein: The locking device (42) further includes a spring seat (424) accommodated in the hollow cavity of the housing (421), wherein the spring seat (424) is sandwiched between the spring (423) and the steel ball (422) for supporting the spring (423).

8. The shift assembly according to claim 5, wherein: The plurality of locking grooves (41) are continuously arranged along the axial direction on the fork shaft (10), each locking groove (41) has an arcuate surface, and the radial depth of each locking groove (41) gradually increases from its axial sides toward the axial center.

9. The shift assembly according to claim 1, wherein: The shift fork shaft (10) comprises a first end and a second end opposite to each other in the axial direction, and an elastic buffer (50) is provided between at least one of the first end and the second end and the gearbox housing.

10. The shift assembly according to claim 9, wherein: The elastic buffer (40) is a spring that is retractable in the axial direction, and the spring is sandwiched between the shift fork shaft (10) and the gearbox housing in the axial direction.

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