Transmission structure of engine reduction gearbox

Abstract

The utility model discloses an engine reduction gearbox transmission structure, which belongs to the technical field of engines and comprises a first shaft, a second shaft and an input shaft, the first shaft is provided with a first gear and a bidirectional pusher dog, the first gear and the first shaft can rotate relatively, the bidirectional pusher dog can move axially relative to the first shaft, and the first gear is provided with a first hole matched with the bidirectional pusher dog; a second gear fixed relative to the second shaft is arranged on the second shaft; the second gear and the first gear are axially staggered; a driving gear is arranged on the input shaft; the driving gear is axially meshed with the first gear and the second gear respectively; the first shaft, the second shaft and the input shaft are distributed in a triangular mode. According to the scheme, the structure is simpler, fewer parts are adopted compared with a traditional structure, the structural arrangement is compact, and the occupied space is small; the three groups of shafts in the transmission structure are triangularly distributed, and the two largest transmission gears are staggered, so that the overall size of the transmission structure can be reduced; the transmission efficiency is higher, the energy consumption is reduced, and a transmission chain is shorter.

Description

TECHNICAL FIELD

[0001] The utility model relates to a transmission structure more specifically, it relates to a kind of engine reduction gearbox transmission structure. BACKGROUND

[0002] The transmission structure in engine reduction gearbox is used to control the reverse and forward of vehicle, realizes the driving demand of vehicle in different scenes.The transmission structure of existing reduction gearbox generally adopts gear meshing two by two, the distance between transmission shaft is the sum of gear radius, occupies large space, many parts, to cause reduction gearbox also can be more large in whole;And also cause production cost to increase, maintenance difficulty increases.

[0003] For example: China patent announcement No.CN208935286U, announcement date is June 4, 2019, and the utility model is named a motorcycle engine transmission, including main shaft assembly, auxiliary shaft assembly, speed change drum and shift fork group;Wherein, main shaft assembly is engaged with auxiliary shaft assembly, and shift fork group is connected between speed change drum, main shaft assembly and auxiliary shaft assembly.Main shaft assembly includes driving shaft and driving gear set installed on driving shaft, and driving gear set includes first driving gear, second driving gear, third driving gear, fourth driving gear, fifth driving gear and sixth driving gear.Auxiliary shaft assembly includes auxiliary shaft and driven gear set installed on auxiliary shaft;Driven gear set includes first driven gear, second driven gear, third driven gear, fourth driven gear, fifth driven gear and sixth driven gear.The gear shifting of the motorcycle engine transmission of this scheme is smooth, effectively reduces fuel consumption, and improves energy transmission efficiency.But the overall structure of the motorcycle transmission is complex, and the parts are more, and transmission energy consumption will also increase accordingly, in addition, the overall structure of the speed reducer will occupy large space, and the arrangement difficulty on vehicle will also increase accordingly. UTILITY MODEL CONTENT

[0004] The utility model overcomes the problems of complex transmission structure in existing engine reduction gearbox, large space occupation and low transmission efficiency, provides a kind of engine reduction gearbox transmission structure, and the transmission structure in the reduction gearbox of this scheme is simple, compact in structure arrangement, and transmission efficiency is high.

[0005] To solve the above technical problems, the utility model discloses the following technical scheme: a kind of engine reduction gearbox transmission structure, including shaft one, shaft two and input shaft, first gear and bidirectional pawl are equipped on the shaft one, first gear can rotate relative to the shaft one, bidirectional pawl can move relative to the shaft one axial, first gear is equipped with hole one being adapted to bidirectional pawl;Second gear is equipped on the shaft two and is fixed relative to the shaft two;Second gear and first gear are axially misaligned;Drive gear is equipped on the input shaft, and drive gear is axially meshed with first gear and second gear respectively;Wherein, the shaft one, the shaft two and the input shaft are triangular distribution.In the scheme, drive gear on input shaft is meshed with first gear and second gear on the shaft one and the shaft two respectively to drive transmission structure movement, bidirectional pawl can control first gear to slide on the shaft one, so that bidirectional pawl cooperates with the gear structure on the shaft one, drives corresponding gear to rotate;Second gear and first gear are misaligned in axial direction, and end face is also overlapped, so that the distance between the shaft one and the shaft two can be greatly reduced, so as to reduce the occupied space of transmission structure, and the drive tooth on the input shaft is used to drive first gear and second gear to rotate simultaneously, the shaft one, the shaft two and the input shaft are triangular distribution, which can further reduce the radial dimension between the three, so that the transmission structure is more compact, and the transmission efficiency is higher.

[0006] As preferred, the shaft one is provided with a third gear rotatable relative to the shaft one, the third gear is arranged on the side of the bidirectional pawl away from the first gear, the third gear is provided with a hole two adapted to the bidirectional pawl, the shaft two is provided with a fourth gear fixed relative to the shaft two, and the third gear is meshed with the fourth gear. The bidirectional pawl can also cooperate with the third gear to form a circumferential fixation of the third gear and the shaft one, thereby realizing gear shifting of the reduction gearbox transmission structure; the fourth gear and the third gear are meshed to form one of the transmission chains.

[0007] As preferred, the shaft one is provided with a fifth gear fixed relative to the shaft one on the side away from the bidirectional pawl, the shaft two is provided with a sixth gear rotatable relative to the shaft two, and the fifth gear is meshed with the sixth gear. The fifth gear on the shaft one is a fixed gear, and the sixth gear on the shaft two is an adjustable gear, thereby realizing control of different gears.

[0008] As preferred, the shaft two is provided with a one-way pawl arranged on the side of the sixth gear away from the fourth gear, and the sixth gear is provided with a hole three adapted to the one-way pawl. The sixth gear is controlled by the one-way pawl, so that the sixth gear can be circumferentially fixed with the shaft two.

[0009] As preferred, the shaft one and the shaft two are each provided with a bearing. The bearing can ensure the rotation effect of the shaft one and the shaft two, and also ensure the position accuracy of the shaft one and the shaft two in the reduction gearbox, thereby ensuring good transmission effect.

[0010] As preferred, the shaft one is connected with an output shaft in transmission. The output power is transmitted through the connection between the shaft one and the output shaft.

[0011] As preferred, the bidirectional pawl is connected with the unidirectional pawl in the gear shifting assembly. The gear shifting assembly can control the bidirectional pawl and the unidirectional pawl to move on the shaft one and the shaft two respectively, so as to realize the corresponding movement of the corresponding transmission gear and realize the gear shifting operation.

[0012] As preferred, the gear shifting assembly comprises a gear shifting lever, the gear shifting lever is provided with a first shift fork connected with the bidirectional pawl and a second shift fork connected with the unidirectional pawl. The first shift fork controls the movement of the bidirectional pawl, and the second shift fork controls the movement of the unidirectional pawl.

[0013] As preferred, the gear shifting assembly further comprises a gear shifting drum, the gear shifting drum is provided with a first gear shifting slot and a second gear shifting slot, the first shift fork and the second shift fork are both provided with a shift fork head, and the shift fork head is matched with the first gear shifting slot and the second gear shifting slot respectively. The gear shifting drum controls the movement of the shift fork through the gear shifting slot, and then drives the movement of the pawl, so as to realize the gear shifting operation.

[0014] As preferred, the bidirectional pawl and the unidirectional pawl are both provided with a sliding guide structure between the bidirectional pawl and the shaft one and between the unidirectional pawl and the shaft two. The sliding guide structure is arranged between the bidirectional pawl and the shaft one and between the unidirectional pawl and the shaft two, so as to ensure that the pawl can move on the shaft, and also ensure the circumferential limiting between the pawl and the shaft.

[0015] Compared with the prior art, the utility model has the advantages of (1) simpler structure, fewer parts than the traditional structure; (2) compact structure, small space occupation; three groups of shafts in the transmission structure are distributed in a triangular shape, and the two largest transmission gears are arranged staggeredly, which can all reduce the overall size of the transmission structure; (3) higher transmission efficiency, lower energy consumption, and shorter transmission chain. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 It is the axonometric view of the utility model.

[0017] Figure 2 It is the axonometric view of the utility model from another angle.

[0018] Figure 3 It is the structural sectional view of the shaft one and the shaft two of the utility model.

[0019] Figure 4 It is the structural schematic view of the gear shifting drum of the utility model.

[0020] Figure 5 It is the structural schematic view of the bidirectional pawl of the utility model.

[0021] Figure 6 This is a schematic diagram of the shaft structure of this utility model.

[0022] Figure 7 This is a schematic diagram of the unidirectional claw structure of this utility model.

[0023] In the diagram: 1. Shaft 1, 2. Shaft 2, 3. Input shaft, 4. First gear, 5. Bidirectional shifter, 6. Second gear, 7. Drive gear, 8. Third gear, 9. Fourth gear, 10. Fifth gear, 11. Sixth gear, 12. Unidirectional shifter, 13. First bearing, 14. Second bearing, 15. Output shaft, 16. Gear shift lever, 17. First shift fork, 18. Second shift fork, 19. Gear shift drum, 20. First shift groove, 21. Second shift groove, 22. Hole 1, 23. Hole 2, 24. Hole 3, 25. Sliding guide structure. Detailed Implementation

[0024] The technical solution of this utility model will be further described in detail below through specific embodiments and in conjunction with the accompanying drawings.

[0025] Example 1: As Figures 1 to 7 The illustrated engine reduction gearbox transmission structure includes a first shaft 1, a second shaft 2, and an input shaft 3. A first gear 4, a third gear 8, and a fifth gear 10 are arranged on the first shaft 1. A second gear 6, a fourth gear 9, and a sixth gear 11 are arranged on the second shaft 2. A drive gear 7 is arranged on the input shaft 3. The first gear 4 and the second gear 6 are axially offset. Both the first gear 4 and the second gear 6 mesh with the drive gear 7 on the input shaft 3. The third gear 8 meshes with the fourth gear 9, and the fifth gear 10 meshes with the sixth gear 11. A bidirectional pawl 5 is provided between the first gear 4 and the third gear 8, and a unidirectional pawl 12 is provided under the sixth gear 11. Torque is input through the input shaft 3, causing the drive gear 7 to rotate the first gear 4 and the second gear 6. The pawls then engage with the corresponding gears to change the transmission chain, thus achieving gear shifting in the engine reduction gearbox transmission structure. This design simplifies the parts within the transmission structure, resulting in a more compact arrangement and high transmission efficiency.

[0026] Specifically, shaft 1 has a first gear 4, a third gear 8, and a fifth gear 10 arranged sequentially from top to bottom, while shaft 2 has a second gear 6, a fourth gear 9, and a sixth gear 11 arranged sequentially from top to bottom. Shaft 1 and shaft 2 are distributed in parallel. The first gear 4 and the second gear 6 are the two gears with the largest radii in the transmission structure, thus achieving a speed reduction effect when meshing with the drive gear 7 of the input shaft 3. The first gear 4 and the second gear 6 are axially offset, meaning that the second gear 6 and the first gear 4 do not mesh, forming two independent transmission gears. Furthermore, the first gear 4 and the second gear 6 are arranged overlapping at their axial end faces, such as...Figure 3 As shown, the upper surface of the first gear 4 is close to the lower surface of the second gear 6, and the first gear 4 and the second gear 6 do not contact, avoiding interference collision; in this way, the distance between the shaft one 1 and the shaft two 2 can be further reduced; specifically, the minimum distance between the shaft one 1 and the shaft two 2 is theoretically equal to the radius of the gear with a larger radius among the first gear 4 and the second gear 6, that is, the distance between the shaft one 1 and the shaft two 2 can be reduced to the length of the radius of the gear with the maximum radius; however, considering the meshing of the third gear 8 and the fourth gear 9, the fifth gear 10 and the sixth gear 11, the actual distance may be slightly larger; but the design in this way can still make the transmission structure of the reduction gearbox compact.

[0027] The input shaft 3 is arranged in parallel with the shaft one 1 and the shaft two 2, and since the first gear 4 on the shaft one 1 and the second gear 6 on the shaft two 2 are distributed in staggered overlap, the input shaft 3 and the shaft one 1 and the shaft two 2 form a triangular distribution; the input shaft 3 is provided with a driving gear 7 at one end, and the axial length of the driving gear 7 is adapted to the axial length of the first gear 4 and the second gear 6, and the driving gear 7 simultaneously meshes with the first gear 4 and the second gear 6; wherein the end face gap between the first gear 4 and the second gear 6 will affect the axial length of the driving gear 7, so in the actual design process, it is necessary to reduce the end face gap of the first gear 4 and the second gear 6 as much as possible, thereby reducing the axial length of the driving gear 7, achieving the effect of compact structure and small space occupation. It should be noted that the first gear 4, the second gear 6 and the driving gear 7 all adopt helical gears, which not only have good transmission stability, but also have the advantage of high bearing capacity, and are also suitable for compact structure occasions.

[0028] The third gear 8 and the fifth gear 10 are arranged on the shaft one 1, and the fourth gear 9 and the sixth gear 11 are arranged on the shaft two 2 correspondingly, the third gear 8 and the fourth gear 9 mesh, and the fifth gear 10 and the sixth gear 11 mesh, wherein the first gear 4 and the third gear 8 can rotate circumferentially relative to the shaft one 1, the sixth gear 11 can rotate circumferentially relative to the shaft two 2, the fifth gear 10 is fixedly connected relative to the shaft one 1, and the second gear 6 and the fourth gear 9 are fixedly connected relative to the shaft two 2; in this way, the gears between the shaft one 1 and the shaft two 2 can be avoided from interfering.

[0029] Further, a bidirectional pawl 5 is arranged between the first gear 4 and the third gear 8, the bidirectional pawl 5 is provided with a protruding pawl towards the first gear 4 and towards the third gear 8, and a hole one 22 adapted to the bidirectional pawl 5 is arranged on the inner diameter side of the first gear 4, and a hole two 23 adapted to the bidirectional pawl 5 is arranged on the inner diameter side of the third gear 8; the bidirectional pawl 5 is fixed in the circumferential direction relative to the shaft one 1 and can move in the axial direction along the shaft one 1, when the bidirectional pawl 5 moves towards the first gear 4, the bidirectional pawl 5 cooperates with the first gear 4, the first gear 4 is fixed in the circumferential direction with the shaft one 1 under the action of the bidirectional pawl 5, so that when the first gear 4 rotates, the shaft one 1 will be driven to rotate; similarly, when the bidirectional pawl 5 moves towards the third gear 8, the bidirectional pawl 5 cooperates with the third gear 8, the third gear 8 is fixed in the circumferential direction with the shaft one 1 under the action of the bidirectional pawl 5, so that when the third gear 8 rotates, the shaft one 1 will be driven to rotate. A unidirectional pawl 12 is arranged on the shaft two 2, the unidirectional pawl 12 is located below the sixth gear 11, the unidirectional pawl 12 is also provided with a protruding pawl towards the sixth gear 11 side, the unidirectional pawl 12 is fixed in the circumferential direction relative to the shaft two 2 and can move in the axial direction along the shaft two 2, the inner diameter side of the sixth gear 11 is provided with a hole three 24 adapted to the unidirectional pawl 12, when the unidirectional pawl 12 moves towards the sixth gear 11, the unidirectional pawl 12 cooperates with the sixth gear 11, the sixth gear 11 is fixed in the circumferential direction with the shaft two 2 under the action of the unidirectional pawl 12, so that when the shaft two 2 rotates, the sixth gear 11 will be driven to rotate.

[0030] Further, the inner diameter sides of the unidirectional pawl 12 and the bidirectional pawl 5 are respectively provided with sliding guide structures 25 on the outer peripheral surfaces of the shaft two 2 and the shaft one 1, specifically, the inner diameter side of the unidirectional pawl 12 is provided with an axial sliding groove and an axial protrusion on the outer surface of the shaft two 2; the inner diameter side of the bidirectional pawl 5 is provided with an axial sliding groove and an axial protrusion on the outer surface of the shaft one 1, so that not only can the unidirectional pawl 12 and the bidirectional pawl 5 slide axially on the shaft two 2 and the shaft one 1 respectively, but also can prevent the unidirectional pawl 12 and the bidirectional pawl 5 from rotating relative to the shaft two 2 and the shaft one 1 respectively.

[0031] In the initial state, the bidirectional pawl 5 is located in the middle position between the first gear 4 and the third gear 8, and does not cooperate with the first gear 4 and the third gear 8, and the unidirectional pawl 12 is located below the sixth gear 11, and does not cooperate with the sixth gear 11; the bidirectional pawl 5 and the unidirectional pawl 12 are controlled to move axially on the shaft one 1 and the shaft two 2 by the gear shifting assembly; and then the movement of the first gear 4, the third gear 8 and the sixth gear 11 in the transmission structure is controlled. Among them, at most only one of the bidirectional pawl 5 and the unidirectional pawl 12 can cooperate with the gear at the same time, that is, when the bidirectional pawl 5 cooperates with the first gear 4 or the third gear 8, the unidirectional pawl 12 and the sixth gear 11 are in a separated state, and when the unidirectional pawl 12 cooperates with the sixth gear 11, the bidirectional pawl 5 and the first gear 4, the third gear 8 are in a separated state.

[0032] The gear shifting assembly includes a gear shifting lever 16 and a gear shifting drum 19, and the gear shifting lever 16 is provided with a first yoke 17 and a second yoke 18, wherein the first yoke 17 is located above the second yoke 18, the first yoke 17 cooperates with the bidirectional pawl 5, the second yoke 18 cooperates with the unidirectional pawl 12, and the first yoke 17 and the second yoke 18 can slide axially on the gear shifting lever 16, and the gear shifting lever 16 is parallel to the shaft one 1 and the shaft two 2. The unidirectional pawl 12 and the bidirectional pawl 5 are respectively provided with a slot part matched with the second yoke 18 and the first yoke 17, so that when the first yoke 17 and the second yoke 18 move axially on the gear shifting lever 16, the bidirectional pawl 5 and the unidirectional pawl 12 will be correspondingly driven to move axially on the shaft one 1 and the shaft two 2, and then the corresponding gears and the shaft one 1 and the shaft two 2 are axially fixed into the transmission chain.

[0033] The gear shifting drum 19 is used to control the movement of the first yoke 17 and the second yoke 18, and the first yoke 17 and the second yoke 18 can realize independent movement. Specifically, the first gear shifting slot 20 and the second gear shifting slot 21 are arranged on the gear shifting drum 19, and the yoke head is arranged on the first yoke 17 and the second yoke 18, and the first yoke 17 and the first gear shifting slot 20, and the second yoke 18 and the second gear shifting slot 21 are connected by the yoke head on the first yoke 17 and the yoke head on the second yoke 18. The yoke head can move along the slot type on the first gear shifting slot 20 and the second gear shifting slot 21, so as to drive the first yoke 17 and the second yoke 18 to move axially on the gear shifting lever 16. For example, Figure 4As shown, in the illustrated direction, the first gear shift line groove 20 and the second gear shift line groove 21 are distributed with four circumferential position nodes from the leftmost to the rightmost; wherein the first gear shift line groove 20 has three kinds of axial position nodes of high, medium and low, and the second gear shift line groove 21 has two kinds of axial position nodes of high and low. Specifically, from left to right, the axial position nodes of the first gear shift line groove 20 are high, medium, medium and low respectively; and the axial position nodes of the second gear shift line groove 21 are low, low, high and low. When the first shift fork 17 and the "high" axial position node of the first gear shift line groove 20 cooperate, at this time, the first shift fork 17 drives the bidirectional pawl 5 to cooperate with the first gear 4; when the first shift fork 17 and the "medium" axial position node of the first gear shift line groove 20 cooperate, at this time, the first shift fork 17 drives the bidirectional pawl 5 to be located between the first gear 4 and the third gear 8 (the bidirectional pawl 5 does not cooperate with the first gear 4 and the third gear 8); when the first shift fork 17 and the "low" axial position node of the first gear shift line groove 20 cooperate, at this time, the first shift fork 17 drives the bidirectional pawl 5 to cooperate with the third gear 8; when the second shift fork 18 and the "high" axial position node of the second gear shift line groove 21 cooperate, the second shift fork 18 drives the unidirectional pawl 12 to cooperate with the sixth gear 11; when the second shift fork 18 and the "low" axial position node of the second gear shift line groove 21 cooperate, at this time, the second shift fork 18 drives the unidirectional pawl 12 to separate from the sixth gear 11.

[0034] Bearings are arranged on the shaft one 1 and the shaft two 2, which are used for the rotational connection of the shaft one 1 and the shaft two 2 relative to the reduction gearbox, so as to ensure the smooth rotation of the shaft one 1 and the shaft two 2. Specifically, the first bearing 13 is arranged at the upper and lower ends of the shaft one 1, and the second bearing 14 is arranged at the upper and lower ends of the shaft two 2; the output shaft 15 is further arranged at one end of the shaft one 1, and in this embodiment, the output shaft 15 is arranged at the end of the shaft one 1 close to the fifth gear 10. The shaft one 1 and the output shaft 15 are connected through the meshing of bevel gears.

[0035] The working principle of the pawl and the gear when they cooperate is as follows.

[0036] When the bidirectional pawl 5 cooperates with the first gear 4, it is in the reverse gear state, at this time, the bidirectional pawl 5 and the first gear 4 are circumferentially fixed with the shaft one 1, when the input shaft 3 rotates, the first gear 4 and the second gear 6 will rotate, since the first gear 4 and the shaft one 1 are circumferentially fixed, the shaft one 1 will rotate, thereby driving the output shaft 15 to rotate and output torque. At this time, the meshing transmission of the drive gear 7 and the second gear 6, the meshing transmission of the third gear 8 and the fourth gear 9, and the meshing transmission of the fifth gear 10 and the sixth gear 11 do not affect the output of the shaft one 1, and since the remaining gears are meshing transmission, it ensures that the shaft one 1 can rotate normally.

[0037] When the bidirectional pawl 5 is matched with the third gear 8, it is in the low speed gear state, at this time, the bidirectional pawl 5 and the third gear 8 are circumferentially fixed with the shaft one 1, when the input shaft 3 rotates, the second gear 6 rotates, since the second gear 6 and the fourth gear 9 are fixedly connected with the shaft two 2, the second gear 6 drives the shaft two 2 and the fourth gear 9 to rotate, the fourth gear 9 and the third gear 8 are engaged, thereby driving the shaft one 1 to rotate, so as to drive the output shaft 15 to rotate and output torque. At this time, the driving gear 7 and the first gear 4 are engaged to drive, the fifth gear 10 and the sixth gear 11 are engaged to drive, which will not affect the rotation output of the shaft one 1, and since they are engaged to drive, it ensures that the shaft two 2 and the shaft one 1 can rotate normally.

[0038] When the one-way pawl 12 is matched with the sixth gear 11, it is in the high speed gear state, at this time, the one-way pawl 12 and the sixth gear 11 are circumferentially fixed with the shaft two 2, when the input shaft 3 rotates, the sixth gear 11 on the shaft two 2 rotates, thereby driving the fifth gear 10 on the shaft one 1 to rotate, the fifth gear 10 and the shaft one 1 are fixedly connected, thereby driving the shaft one 1 to rotate and output, so as to finally drive the output shaft 15 to rotate and output torque. At this time, the driving gear 7 and the first gear 4 are engaged to drive, the third gear 8 and the fourth gear 9 are engaged to drive, which will not affect the rotation output of the shaft one 1, and since they are engaged to drive, it ensures that the shaft one 1 and the shaft two 2 can rotate normally.

[0039] The control principle of the gear shifting assembly and the pawl is shown in the following table.

[0040] First shift fork and first shift rail axial position node Second shift fork and second shift rail axial position node State High Low Bidirectional pawl and first gear engaged Medium Low Bidirectional pawl and unidirectional shift fork not engaged with gear Medium High Unidirectional pawl and sixth gear engaged Low Low Bidirectional pawl and third gear engaged

Claims

1. A transmission structure for an engine reduction gearbox, characterized in that, include Shaft 1, the shaft 1 is provided with a first gear and a bidirectional pawl, the first gear can rotate relative to shaft 1, the bidirectional pawl can move axially relative to shaft 1, and the first gear is provided with a hole 1 that is adapted to the bidirectional pawl; Shaft 2, wherein a second gear is fixed relative to shaft 2; the second gear is axially offset from the first gear; An input shaft is provided with a drive gear, which meshes axially with a first gear and a second gear respectively. Axis 1, Axis 2, and the input axis are arranged in a triangular pattern.

2. The engine reduction gearbox transmission structure according to claim 1, characterized in that, The first shaft is provided with a third gear that can rotate relative to the first shaft. The third gear is located on the side of the bidirectional pawl away from the first gear. The third gear is provided with a second hole that is adapted to the bidirectional pawl. The second shaft is provided with a fourth gear that is fixed to the second shaft. The third gear meshes with the fourth gear.

3. The engine reduction gearbox transmission structure according to claim 2, characterized in that, A fifth gear, fixed to the first shaft, is provided on the side of the third gear away from the bidirectional pawl. A sixth gear, which can rotate relative to the second shaft, is provided on the second shaft. The fifth gear meshes with the sixth gear.

4. The engine reduction gearbox transmission structure according to claim 3, characterized in that, The shaft 2 is provided with a one-way pawl, which is located on the side of the sixth gear away from the fourth gear. The sixth gear is provided with a hole 3 that is adapted to the one-way pawl.

5. An engine reduction gearbox transmission structure according to any one of claims 1 to 4, characterized in that, Both shaft one and shaft two are equipped with bearings.

6. An engine reduction gearbox transmission structure according to any one of claims 1 to 4, characterized in that, The shaft is connected to an output shaft.

7. The engine reduction gearbox transmission structure according to claim 4, characterized in that, The bidirectional shifter and the unidirectional shifter are connected to the gear shifting assembly.

8. The engine reduction gearbox transmission structure according to claim 7, characterized in that, The gear shifting assembly includes a gear shift lever, which has a first shift fork connected to the bidirectional shift pawl and a second shift fork connected to the unidirectional shift pawl.

9. The engine reduction gearbox transmission structure according to claim 8, characterized in that, The shifting assembly also includes a shifting drum, which has a first shifting groove and a second shifting groove. Both the first shift fork and the second shift fork have shift fork heads, which cooperate with the first shifting groove and the second shifting groove respectively.

10. An engine reduction gearbox transmission structure according to any one of claims 7 to 9, characterized in that, The bidirectional pawl and the unidirectional pawl are respectively provided with sliding guide structures between them and the first shaft and the second shaft.

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