Gear shifting structure for high-gear and low-gear switching, gearbox and vehicle

Abstract

The invention relates to the technical field of gearboxes, and discloses a gear shifting structure for high and low gear switching, a gearbox and a vehicle, the structure comprises a low-gear gear assembly, a high-gear gear assembly, a shifting fork connecting unit, a sliding sleeve assembly and an output shaft; the low-speed-gear gear assembly, the high-speed-gear gear assembly and the sliding sleeve assembly are all arranged on the output shaft in a sleeving and meshing mode, and the sliding sleeve assembly is located between the low-speed-gear gear assembly and the high-speed-gear gear assembly; one end of the shifting fork connecting unit is connected with the gear shifting mechanism, the other end of the shifting fork connecting unit is meshed with the sliding sleeve assembly, and the shifting fork connecting unit drives the sliding sleeve assembly to be meshed with the high-gear gear assembly during high-gear shifting; when a low-speed gear is shifted, the shifting fork connecting unit drives the sliding sleeve assembly to be meshed with the low-speed gear assembly. The sliding sleeve assembly is located between the low-speed-gear gear assembly and the high-speed-gear gear assembly and can be smoothly switched between the low-speed-gear gear assembly and the high-speed-gear gear assembly through driving of the shifting fork connecting unit, and therefore the gear shifting smoothness is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of gearboxes, and in particular to a gear shifting structure for switching between high and low gears, a gearbox and a vehicle. Background Art

[0002] As an important pillar industry of national economic construction, construction machinery is widely used in many fields such as construction, mining, oil fields, steel, etc., and plays an irreplaceable role in improving the efficiency of economic construction. However, there are many types of construction machinery, and the differences between each model are large. Their transmission systems also have their own characteristics, so the customization demand of the transmission system is high.

[0003] As the export market continues to grow, traditional imported transmission systems can no longer meet the actual needs of the current market in terms of output, quality and service. Domestic manufacturers generally hope to achieve localization of transmission systems to reduce dependence on imported components and improve product competitiveness. Therefore, developing domestic engineering machinery transmission systems with independent intellectual property rights has become an inevitable trend in the development of the industry.

[0004] However, the working environment of construction machinery vehicles is usually harsh, and the gear shifting conditions are frequent. During the gear shifting process, the speed and torque of the transmission system will change suddenly, which often leads to poor gear shifting smoothness of the transmission system and may even cause clutch failure. These problems not only seriously affect the gear shifting comfort and reliability of construction machinery vehicles, but may also cause the driver's subjective experience to deteriorate, further affecting work efficiency and safety.

[0005] In view of the above background, there is an urgent need for a new technical solution that can solve the poor gear shifting smoothness of the transmission system of engineering machinery and improve the gear shifting comfort and reliability. Summary of the invention

[0006] The object of the present invention is to provide a shifting structure, a gearbox and a vehicle for high-low gear switching, so as to solve the technical problem of poor smoothness of high-speed and low-speed gear shifting in the prior art.

[0007] The present invention is achieved through the following technical solutions: In a first aspect, the present invention provides a shifting structure for high and low gear switching, comprising a low gear assembly, a high gear assembly, a shift fork connecting unit, a sliding sleeve assembly and an output shaft; The low-speed gear assembly, the high-speed gear assembly and the sliding sleeve assembly are all sleeved and meshed on the output shaft, wherein the sliding sleeve assembly is located between the low-speed gear assembly and the high-speed gear assembly; One end of the shift fork connecting unit is connected to the shift mechanism, and the other end is meshed on the sliding sleeve assembly. When shifting to a high gear, the shift fork connecting unit drives the sliding sleeve assembly to mesh with the high gear gear assembly; when shifting to a low gear, the shift fork connecting unit drives the sliding sleeve assembly to mesh with the low gear gear assembly.

[0008] Preferably, the fork connecting unit comprises a fork shaft and a fork; One end of the shift fork shaft is connected to the shift mechanism, and the other end is sleeved and fixed on the shift fork sleeve of the shift fork. The shift fork foot of the shift fork is meshed and arranged on the sliding sleeve assembly.

[0009] Furthermore, the fork sleeve and the fork shaft are fixed by a first screw and a second screw; The first screw abuts against the end side wall of the fork shaft through the fork sleeve; the second screw passes through the fork sleeve and the fork shaft in sequence.

[0010] Further, the sliding sleeve assembly includes a sliding sleeve and a sliding sleeve gear seat; The sleeve tooth seat is meshed on the output shaft, and the sleeve movable sleeve is meshed on the sleeve tooth seat; wherein, a connecting groove is provided on the sleeve; the shift fork foot is meshed on the connecting groove, and when shifting to a high gear, the shift fork drives the sleeve to mesh with the high-speed gear assembly on the sleeve tooth seat; when shifting to a low gear, the shift fork drives the sleeve to mesh with the low-speed gear assembly on the sleeve tooth seat.

[0011] Furthermore, a first spline is provided on the side of the sleeve that meshes with the low-speed gear assembly, and a second spline is provided on the side of the sleeve that meshes with the high-speed gear assembly, wherein a separation groove is provided between the first spline and the second spline, and the separation groove can separate the first spline and the second spline and accumulate oil for lubricating the sleeve and the sleeve gear seat.

[0012] Furthermore, the clearance of the second spline is greater than the clearance of the first spline.

[0013] Furthermore, the low-speed gear assembly meshing includes a low-speed gear, a first needle roller bearing and a first spline sleeve, the first spline sleeve meshing sleeve is arranged on the output shaft, the first needle roller bearing meshing sleeve is arranged on the first spline sleeve, and the low-speed gear meshing sleeve is arranged on the first needle roller bearing. When shifting to a low speed gear, the shift fork drives the sliding sleeve so that the first spline of the sliding sleeve meshes with the low-speed gear.

[0014] Furthermore, the high-speed gear assembly meshing includes a high-speed gear, a second needle roller bearing and a second spline sleeve, the second spline sleeve meshing sleeve is arranged on the output shaft, the second needle roller bearing meshing sleeve is arranged on the second spline sleeve, and the high-speed gear meshing sleeve is arranged on the second needle roller bearing. When shifting to high gear, the shift fork drives the sliding sleeve so that the second spline of the sliding sleeve meshes with the high-speed gear.

[0015] In a second aspect, the present invention further provides a gearbox, comprising a gearbox housing and a shift structure for high and low gear switching as described above; Bearings are respectively sleeved on both sides of the gearbox housing, and the output shaft penetrates the gearbox housing through the bearings. The low-speed gear assembly, the high-speed gear assembly and the sliding sleeve assembly are all sleeved in the gearbox housing and meshed on the output shaft, wherein a first gasket is provided between the low-speed gear assembly and the bearing close to the low-speed gear assembly side; a second gasket is provided between the high-speed gear assembly and the bearing close to the high-speed gear assembly side; the shift fork connecting unit is located in the gearbox housing, wherein one end of the shift fork connecting unit is connected to the shifting mechanism, and the other end is meshed on the sliding sleeve assembly, when shifting to high gear, the shift fork connecting unit drives the sliding sleeve assembly to mesh with the high-speed gear assembly; when shifting to low gear, the shift fork connecting unit drives the sliding sleeve assembly to mesh with the low-speed gear assembly.

[0016] In a third aspect, the present invention further provides a vehicle, comprising a gearbox as described above.

[0017] Compared with the prior art, the present invention has the following beneficial technical effects: The present invention provides a shifting structure for high and low gear switching, wherein the sliding sleeve assembly is located between the low-speed gear assembly and the high-speed gear assembly, and can smoothly switch between the two through the drive of a shift fork connecting unit, thereby avoiding the impact and frustration caused by direct meshing or separation of gears in a traditional shifting structure, thereby improving the smoothness of the shifting. One end of the shift fork connecting unit is connected to the shifting mechanism, and the other end is meshed on the sliding sleeve assembly. Through the precise operation of the shifting mechanism, the shift fork connecting unit can drive the sliding sleeve assembly to accurately mesh with the gear assembly of the required gear, thereby ensuring the smoothness and accuracy of the shifting process and improving the smoothness of the shifting.

[0018] Furthermore, the fork sleeve and the fork shaft are fixed by a first screw and a second screw; wherein the first screw abuts against the end side wall of the fork shaft through the fork sleeve, and the remaining gap is eaten up by the cooperation between the conical surface of the lower end and the ring groove of the fork shaft, so that the connection between the fork and the fork shaft is tighter and more anti-loosening; the second screw is sequentially implemented through the fork sleeve and the fork shaft, plays a major positioning role, and the hinged light rod part bears most of the shear force during gear shifting.

[0019] Furthermore, when shifting, since the sliding sleeve is pushed a long distance in the high-speed gear, a first spline is provided on the side of the sliding sleeve meshing with the low-speed gear assembly, and a second spline is provided on the side of the sliding sleeve meshing with the high-speed gear assembly, wherein a separation groove is provided between the first spline and the second spline, and the separation groove can separate the first spline and the second spline while accumulating oil for lubricating the sliding sleeve and the sliding sleeve tooth seat. The separation groove can not only physically separate the first spline and the second spline to ensure the accuracy of the sliding sleeve when switching between different gears, but also accumulate oil. The accumulated oil plays a good lubricating role in the movement of the sliding sleeve, reducing the friction between the sliding sleeve and the gear assembly, thereby extending the service life of the parts. The design of the separation groove enables the oil to more effectively lubricate the contact surface between the sliding sleeve and the gear assembly, reducing the resistance and jamming phenomenon during the gear shifting process, and improving the gear shifting efficiency. The well-lubricated gear shifting structure reduces the wear and failure rate of the parts, thereby improving the reliability of the entire transmission system.

[0020] Furthermore, the gap of the second spline is greater than the gap of the first spline, which makes it easier for the sliding sleeve to move in the high-speed gear direction, ensures the stability and accuracy of the gear shifting process, and improves the smoothness of the gear shifting.

[0021] Furthermore, the high-speed gear and the low-speed gear are relatively thinned in the axial direction, which not only meets the space requirement of the shifting engagement of the sliding sleeve, but also reduces the weight of the gear and saves costs.

[0022] The present invention also provides a gearbox, which ensures accurate matching and stable operation between components by sleeve bearings on both sides of the gearbox housing and adjusting the clearance between the gear assembly and the bearings using a first gasket and a second gasket, which not only improves the operation accuracy of the gearbox, but also effectively reduces the friction and wear between components. The gearbox adopts a high-low gear switching shifting structure, and realizes smooth switching between high and low gears through the accurate matching of the fork connection unit and the sliding sleeve assembly, which not only improves the accuracy of the gear shifting, but also makes the gear shifting process more stable and smooth. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic diagram of a gear shifting structure in an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of the sliding sleeve in an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of the shift fork and the locking screw in an embodiment of the present invention; Figure 4 A schematic diagram of high-speed shifting operation in an embodiment of the present invention; Figure 5 This is a schematic diagram of low-speed shifting operation in an embodiment of the present invention; In the figure: 1. shift fork shaft; 2. shift fork; 3. sleeve; 4. sleeve gear seat; 5. low-speed gear; 6. high-speed gear; 7. first needle roller bearing; 8. first spline sleeve; 9. first gasket; 10. output shaft; 11. gearbox housing; 12. first screw; 13. second screw; 14. second needle roller bearing; 15. first spline sleeve; 16. second gasket; 31. connecting groove; 32. dividing groove; 33. first spline; 34. second spline. DETAILED DESCRIPTION

[0024] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings 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 should fall within the scope of protection of the present invention.

[0025] The present invention is further described in detail below in conjunction with the accompanying drawings: The object of the present invention is to provide a shifting structure, a gearbox and a vehicle for high-low gear switching, so as to solve the technical problem of poor smoothness of high-speed and low-speed gear shifting in the prior art.

[0026] Example 1 See also Figure 1 In one embodiment of the present invention, a shifting structure for switching between high and low gears is provided, comprising a low-speed gear assembly, a high-speed gear assembly, a shift fork connecting unit, a sleeve assembly and an output shaft 10; the low-speed gear assembly, the high-speed gear assembly and the sleeve assembly are all sleeved and meshed on the output shaft 10, wherein the sleeve assembly is located between the low-speed gear assembly and the high-speed gear assembly; one end of the shift fork connecting unit is connected to the shifting mechanism, and the other end is meshed on the sleeve assembly, when shifting to a high gear, the shift fork connecting unit drives the sleeve assembly to mesh with the high-speed gear assembly; when shifting to a low gear, the shift fork connecting unit drives the sleeve assembly to mesh with the low-speed gear assembly.

[0027] Specifically, the shift fork connecting unit includes a shift fork shaft 1 and a shift fork 2; one end of the shift fork shaft 1 is connected to the shift mechanism, and the other end is sleeved and fixed on the shift fork sleeve of the shift fork 2; the shift fork foot of the shift fork 2 is meshed and arranged on the sliding sleeve assembly.

[0028] In this embodiment, one end of the fork shaft 1 is connected to the shift mechanism, which is usually located in the cab and operated by the driver through the shift lever. When the driver needs to shift gears, the shift mechanism is pushed through the shift lever, thereby pushing the fork shaft 1. After being pushed by the shift mechanism, the fork shaft 1 moves along its axial direction. The fork shaft 1 also plays a guiding and positioning role, ensuring that the fork 2 can accurately and stably move to the required position to achieve correct shifting. The other end of the fork shaft 1 is sleeved and fixed on the fork sleeve of the fork 2, so that the movement of the fork shaft 1 can drive the fork 2 to move together. The fork feet of the fork 2 are key components that are meshed and arranged on the sliding sleeve assembly. They are usually connected to the synchronizer or shift gear in the transmission. When the fork 2 moves, the fork feet will drive the synchronizer or shift gear to move. The movement of the fork feet will cause the synchronizer or shift gear to engage or disengage with the target gear, thereby achieving the shifting operation. The function of the synchronizer is to make the shifting process smoother and reduce gear shock.

[0029] Among them, according to Figure 3 As shown, the fork sleeve and the fork shaft 1 are fixed by a first screw 12 and a second screw 13; the first screw 12 abuts against the end side wall of the fork shaft 1 through the fork sleeve; the second screw 13 penetrates the fork sleeve and the fork shaft 1 in sequence.

[0030] In this embodiment, the first screw is abutted against the end side wall of the fork shaft through the fork sleeve, and the remaining gap is eaten up by the cooperation between the conical surface of the lower end and the ring groove of the fork shaft, so that the connection between the fork and the fork shaft is tighter and the anti-loosening property is better; the second screw passes through the fork sleeve and the fork shaft in sequence, plays a major positioning role, and the hinged light rod part bears most of the shear force during gear shifting.

[0031] The sleeve assembly includes a sleeve 3 and a sleeve tooth seat 4; the sleeve tooth seat 4 is sleeved and meshed on the output shaft 10, and the sleeve 3 is movably sleeved and meshed on the sleeve tooth seat 4; a connecting groove 31 is provided on the sleeve 3; the shift fork foot is meshed on the connecting groove 31, and when shifting to a high gear, the shift fork 2 drives the sleeve 3 to mesh with the high-speed gear assembly on the sleeve tooth seat 4; when shifting to a low gear, the shift fork 2 drives the sleeve 3 to mesh with the low-speed gear assembly on the sleeve tooth seat 4.

[0032] In this embodiment, when it is necessary to shift to a high gear, the shift mechanism pushes the shift fork 2 to move through the shift fork shaft. The shift fork foot of the shift fork 2 is engaged in the connecting groove 31 of the sleeve 3, and as the shift fork 2 moves, the sleeve 3 also slides on the sleeve tooth seat 4. When the sleeve 3 slides to a position corresponding to the high-speed gear assembly, it engages with the high-speed gear assembly, thereby achieving a high-speed gear shift. When it is necessary to shift to a low-speed gear, the shift mechanism also pushes the shift fork 2 to move through the shift fork shaft, but in the opposite direction. The shift fork foot of the shift fork 2 is engaged in the connecting groove 31 of the sleeve 3 again, driving the sleeve 3 to slide in the opposite direction on the sleeve tooth seat 4. When the sleeve 3 slides to a position corresponding to the low-speed gear assembly, it engages with the low-speed gear assembly, thereby achieving a low-speed gear shift.

[0033] In this embodiment, according to Figure 2 As shown, a first spline 33 is provided on one side of the sleeve 3 meshing with the low-speed gear assembly, and a second spline 34 is provided on the side of the sleeve 3 meshing with the high-speed gear assembly, wherein a separation groove 32 is provided between the first spline 33 and the second spline 34, and the separation groove 32 can separate the first spline 33 and the second spline 34 and store oil for lubricating the sleeve 3 and the sleeve gear seat 4.

[0034] The separation groove 32 can not only effectively separate the first spline 33 and the second spline 34 to avoid interference during the gear shifting process, but also can accumulate oil. When the sleeve 3 slides on the sleeve tooth seat 4, the oil can seep out from the separation groove 32 to lubricate the contact surface between the sleeve 3 and the sleeve tooth seat 4, reducing friction and wear. Through the lubrication effect of the separation groove 32, the durability of the sleeve 3 and the sleeve tooth seat 4 is significantly improved, and the service life of the parts is extended. The precise design of the first spline 33 and the second spline 34 in this embodiment ensures the smooth switching of the sleeve 3 between high and low gears, and improves the accuracy and reliability of gear shifting.

[0035] The gap of the second spline 34 is larger than the gap of the first spline 33 .

[0036] In this embodiment, the larger second spline 34 gap can accommodate more lubricating oil, thereby providing better lubrication effect during the gear shifting process, helping to reduce the impact and noise during the gear shifting, and improving the smoothness of the gear shifting. By adjusting the spline gap, the contact pressure and sliding speed between the sliding sleeve 3 and the gear assembly can be optimized, which helps to reduce friction and wear and extend the service life of parts.

[0037] In this embodiment, the low-speed gear assembly meshing includes a low-speed gear 5, a first needle roller bearing 7 and a first spline sleeve 8. The first spline sleeve 8 is meshingly sleeved on the output shaft 10, the first needle roller bearing 7 is meshingly sleeved on the first spline sleeve 8, and the low-speed gear 5 is meshingly sleeved on the first needle roller bearing 7. When changing to a low-speed gear, the shift fork 2 drives the sliding sleeve 3, so that the first spline 33 of the sliding sleeve 3 meshes with the low-speed gear 5.

[0038] In this embodiment, the high-speed gear assembly meshing includes a high-speed gear 6, a second needle roller bearing 14 and a second spline sleeve 15. The second spline sleeve 15 is meshingly sleeved on the output shaft 10, the second needle roller bearing 14 is meshingly sleeved on the second spline sleeve 15, and the high-speed gear 6 is meshingly sleeved on the second needle roller bearing 14. When shifting to a high gear, the shift fork 2 drives the sliding sleeve 3, so that the second spline 34 of the sliding sleeve 3 meshes with the high-speed gear 6.

[0039] In this embodiment, the inner diameter and height of the needle roller bearing are consistent; the height, inner and outer diameters of the gasket are consistent; the height of the spline sleeve is consistent, the internal spline parameters are consistent, and the surface treatment is consistent.

[0040] In this embodiment, when shifting to a high gear, the shift fork shaft 1 transmits the shifting force to the sliding sleeve 3 through the shift fork 2. The sliding sleeve 3 moves under the force and moves to the right end state. The sliding sleeve 3 meshes with the high gear 6 through the sliding sleeve tooth seat 4 to transmit the power to the output shaft. Figure 4 shown.

[0041] In this embodiment, when shifting down, the shift fork shaft 1 transmits the shifting force to the sliding sleeve 3 through the shift fork 2. The sliding sleeve 3 moves under the force and moves to the left end state. The sliding sleeve 3 meshes with the low gear 5 through the sliding sleeve tooth seat 4 to transmit the power to the output shaft. Figure 5 shown.

[0042] In summary, the present embodiment provides a shifting structure for high and low gear switching, in which the sliding sleeve assembly is located between the low-speed gear assembly and the high-speed gear assembly. The shifting fork connecting unit can smoothly switch between the two, avoiding the impact and frustration caused by the direct meshing or separation of gears in the traditional shifting structure, thereby improving the smoothness of the shifting. One end of the shifting fork connecting unit is connected to the shifting mechanism, and the other end is meshed on the sliding sleeve assembly. Through the precise operation of the shifting mechanism, the shifting fork connecting unit can drive the sliding sleeve assembly to accurately mesh with the gear assembly of the required gear, ensuring the smoothness and accuracy of the shifting process, and improving the smoothness of the shifting.

[0043] The present invention adopts high-pressure oil as power, which is transmitted to the fork shaft 1 through the shift mechanism, and then transmitted to the fork by the fork shaft 1, thereby driving the entire shift structure; the axial size of the entire structure is compressed to the maximum extent in design, the space requirement is reduced, the complexity of the package shell is reduced, and the cost is saved: by adjusting the matching clearance between the sliding sleeve and the high and low gear teeth, wear is reduced and product efficiency is improved.

[0044] Example 2 This embodiment provides a gearbox, including a gearbox housing 11 and a shift structure for high and low gear switching as described above; The gearbox housing 11 is sleeved with bearings on both sides, and the output shaft 10 penetrates the gearbox housing 11 through the bearings. The low-speed gear assembly, the high-speed gear assembly and the sliding sleeve assembly are sleeved in the gearbox housing 11 and meshed on the output shaft 10, wherein a first gasket 9 is provided between the low-speed gear assembly and the bearing close to the low-speed gear assembly side; a second gasket 16 is provided between the high-speed gear assembly and the bearing close to the high-speed gear assembly side; the shift fork connecting unit is located in the gearbox housing 11, wherein one end of the shift fork connecting unit is connected to the shifting mechanism, and the other end is meshed on the sliding sleeve assembly, when shifting to high gear, the shift fork connecting unit drives the sliding sleeve assembly to mesh with the high-speed gear assembly; when shifting to low gear, the shift fork connecting unit drives the sliding sleeve assembly to mesh with the low-speed gear assembly.

[0045] In summary, this embodiment ensures accurate matching and stable operation between components by sleeve bearings on both sides of the gearbox housing and using the first gasket and the second gasket to adjust the gap between the gear assembly and the bearing, which not only improves the operation accuracy of the gearbox, but also effectively reduces the friction and wear between components. The gearbox adopts a high-low gear switching shifting structure, and realizes smooth switching between high and low gears through the precise matching of the fork connection unit and the sliding sleeve assembly, which not only improves the accuracy of the gear shifting, but also makes the gear shifting process more stable and smooth.

[0046] Example 3 This embodiment also provides a vehicle, comprising a gearbox as described above.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A gear shifting structure for high and low gear switching, characterized in that: It comprises a low-speed gear assembly, a high-speed gear assembly, a shift fork connection unit, a sliding sleeve assembly and an output shaft (10); The low-speed gear assembly, the high-speed gear assembly and the sliding sleeve assembly are all sleeved and meshed on the output shaft (10), wherein the sliding sleeve assembly is located between the low-speed gear assembly and the high-speed gear assembly; One end of the shift fork connecting unit is connected to the shift mechanism, and the other end is meshed on the sliding sleeve assembly. When shifting to a high gear, the shift fork connecting unit drives the sliding sleeve assembly to mesh with the high gear gear assembly; when shifting to a low gear, the shift fork connecting unit drives the sliding sleeve assembly to mesh with the low gear gear assembly.

2. A gear shifting structure for high and low gear switching according to claim 1, characterized in that: The shift fork connecting unit comprises a shift fork shaft (1) and a shift fork (2); One end of the shift fork shaft (1) is connected to the shift mechanism, and the other end is sleeved and fixed on the shift fork sleeve of the shift fork (2); the shift fork foot of the shift fork (2) is meshedly arranged on the sliding sleeve assembly.

3. A gear shifting structure for high and low gear switching according to claim 2, characterized in that: The fork sleeve and the fork shaft (1) are fixed by a first screw (12) and a second screw (13); The first screw (12) abuts against the end side wall of the fork shaft (1) through the fork sleeve; the second screw (13) is arranged to penetrate the fork sleeve and the fork shaft (1) in sequence.

4. A shift structure for high and low gear switching according to claim 2, characterized in that: The sliding sleeve assembly comprises a sliding sleeve (3) and a sliding sleeve gear seat (4); The sliding sleeve tooth seat (4) is sleeved and meshed on the output shaft (10), and the sliding sleeve (3) is movably sleeved and meshed on the sliding sleeve tooth seat (4); wherein a connecting groove (31) is provided on the sliding sleeve (3); the shift fork foot is meshed on the connecting groove (31); when shifting to a high gear, the shift fork (2) drives the sliding sleeve (3) to mesh with the high-speed gear assembly on the sliding sleeve tooth seat (4); when shifting to a low gear, the shift fork (2) drives the sliding sleeve (3) to mesh with the low-speed gear assembly on the sliding sleeve tooth seat (4).

5. A shift structure for high and low gear switching according to claim 4, characterized in that: A first spline (33) is provided on one side of the sliding sleeve (3) meshing with the low-speed gear assembly, and a second spline (34) is provided on one side of the sliding sleeve (3) meshing with the high-speed gear assembly, wherein a separation groove (32) is provided between the first spline (33) and the second spline (34), and the separation groove (32) can separate the first spline (33) and the second spline (34) and store oil for lubricating the sliding sleeve (3) and the sliding sleeve tooth seat (4).

6. A gear shifting structure for high and low gear switching according to claim 5, characterized in that: The clearance of the second spline (34) is greater than the clearance of the first spline (33).

7. A shift structure for high and low gear switching according to claim 5, characterized in that: The low-speed gear assembly meshingly comprises a low-speed gear (5), a first needle roller bearing (7) and a first spline sleeve (8); the first spline sleeve (8) meshingly sleeved on the output shaft (10); the first needle roller bearing (7) meshingly sleeved on the first spline sleeve (8); the low-speed gear (5) meshingly sleeved on the first needle roller bearing (7); when shifting to a low-speed gear, the shift fork (2) drives the sliding sleeve (3) so that the first spline (33) of the sliding sleeve (3) meshes with the low-speed gear (5).

8. The shift structure for high and low gear switching according to claim 5, characterized in that: The high-speed gear assembly meshingly comprises a high-speed gear (6), a second needle roller bearing (14) and a second spline sleeve (15); the second spline sleeve (15) meshingly sleeved on the output shaft (10); the second needle roller bearing (14) meshingly sleeved on the second spline sleeve (15); the high-speed gear (6) meshingly sleeved on the second needle roller bearing (14); when shifting to a high-speed gear, the shift fork (2) drives the sliding sleeve (3) so that the second spline (34) of the sliding sleeve (3) meshes with the high-speed gear (6).

9. A gearbox, characterized in that: It comprises a gearbox housing (11) and a gear shifting structure for high and low gear switching according to any one of claims 1 to 8; Bearings are sleeved on both sides of the gearbox housing (11), the output shaft (10) penetrates the gearbox housing (11) through the bearings, the low-speed gear assembly, the high-speed gear assembly and the sliding sleeve assembly are sleeved in the gearbox housing (11) and meshed with the output shaft (10), wherein a first gasket (9) is provided between the low-speed gear assembly and the bearing close to the low-speed gear assembly side; a second gasket (16) is provided between the high-speed gear assembly and the bearing close to the high-speed gear assembly side; the shift fork connecting unit is located in the gearbox housing (11), wherein one end of the shift fork connecting unit is connected to the shifting mechanism, and the other end is meshed with the sliding sleeve assembly, when shifting to high gear, the shift fork connecting unit drives the sliding sleeve assembly to mesh with the high-speed gear assembly; when shifting to low gear, the shift fork connecting unit drives the sliding sleeve assembly to mesh with the low-speed gear assembly.

10. A vehicle, characterized in that: Comprising a gearbox as claimed in claim 9.

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