Manual gear shifting mechanism special for small-displacement engine

Abstract

A manual gear shifting mechanism special for a small-displacement engine comprises a right hand push rod mechanism and a mechanical transmission system which are in transmission connection, the right hand push rod mechanism is arranged at the head position of a vehicle body, and the right hand push rod mechanism comprises a hand push rod, a driving cantilever, a vehicle body fixing frame, an adjusting sleeve, a first fisheye joint and a pull rod; the hand push rod comprises a folding rod assembly and a rod head arranged at the upper end of the folding rod assembly, the folding rod assembly is composed of a bottom rod and a top rod which are matched with each other, an upper joint chuck is arranged at the upper end of the bottom rod, a regular polygon gear groove is formed in the upper joint chuck, a lower joint chuck is arranged at the lower end of the top rod, and a right polygon gear groove is formed in the lower joint chuck. A regular polygon gear block is arranged on the surface of the lower joint chuck, when the regular polygon gear block and the regular polygon gear groove are meshed in a clamped mode, the relative angle of the bottom rod and the top rod is fixed, and when the regular polygon gear block and the regular polygon gear groove are separated from each other, the bottom rod and the top rod can rotate relatively.

Description

Technical Field

[0001] The invention relates to the field of vehicle auxiliary drive devices, and in particular to a manual gear shift mechanism specially used for small-displacement engines. Background Art

[0002] Disadvantages of existing foot-operated shifters: The built-in reverse gear engines generally used in small-displacement beach cars, karts, tricycles, and sleds have forward gears, reverse gears, and neutral gears, but these shift control mechanisms generally adopt a foot-operated shifting method similar to that of two-wheeled electric motorcycles. For example, a foot shifting mechanism for a built-in reverse gear engine disclosed in application No. 201510188233.3 includes a shift positioning device assembly, a foot shift shaft assembly, a foot shift drum assembly, a shift fork shaft assembly, an intermediate shaft assembly, a crankcase left case, a gear chamber cover, and a foot shifting control pedal. However, the current left-side left-foot shifting method is not ergonomic and has low shifting efficiency. Summary of the invention

[0003] In order to solve the above problems, the present invention provides a manual shift mechanism specifically for small-displacement engines: A manual shift mechanism specially used for a small-displacement engine, comprising a right-hand push rod mechanism and a mechanical transmission system connected in a transmission manner, wherein the right-hand push rod mechanism is arranged at the head position of a vehicle body, and comprises a hand push rod, an active cantilever, a vehicle body fixing frame, an adjustment sleeve, a first fisheye joint and a pull rod, wherein the lower ends of the hand push rod and the active cantilever are fixedly connected to the same fixing frame shaft, wherein the hand push rod is movably hinged to the vehicle body fixing frame through the fixing frame shaft, and the vehicle body fixing frame is fixedly connected to the vehicle body; The hand push rod includes a folding rod assembly, which is composed of a bottom rod and a top rod that match each other, the lower end of the bottom rod is fixedly connected to the radial direction of the fixed frame axis, the upper end of the bottom rod is provided with an upper joint chuck, the upper joint chuck is radially fixedly connected to the upper end of the bottom rod, the upper joint chuck is provided with a regular polygonal gear groove on the side facing away from the active cantilever, the lower end of the top rod is provided with a lower joint chuck, the lower joint chuck is radially fixedly connected to the lower end of the top rod, and the lower joint chuck is provided with a regular polygonal gear block that matches the regular polygonal gear groove, when the regular polygonal gear block and the regular polygonal gear groove are engaged with each other, the relative angle between the bottom rod and the top rod is fixed, and when the regular polygonal gear block and the regular polygonal gear groove are disengaged from each other, the bottom rod and the top rod can rotate relative to each other.

[0004] Preferably, the active cantilever and the first fisheye joint are movably hinged to each other through a fisheye pin, and the fisheye pin passes through concentric pin holes provided in the upper joint chuck and the lower joint chuck, and a radially protruding limiting flange is provided at one end of the fisheye pin corresponding to the lower joint chuck, and the limiting flange is used to prevent the upper joint chuck and the lower joint chuck from detaching from each other, and a radial pin hole is provided at one end of the fisheye pin corresponding to the first fisheye joint, and an open pin is inserted in the pin hole, and the open pin is used to limit the relative position of the active cantilever and the first fisheye joint.

[0005] Preferably, a plurality of stepping grooves corresponding to the outer edges of the regular polygon are evenly distributed on the outer circumference of the regular polygonal shift groove, and a plurality of stepping blocks corresponding to the outer edges of the regular polygon are evenly distributed on the outer circumference of the regular polygonal shift block, and the stepping blocks and the stepping grooves form a detachable snap-in fit. The number of sides of the regular polygonal shift groove is the same as the number of stepping grooves, so that the snap-in fit of the bottom rod and the top rod can be achieved regardless of the angle between them.

[0006] Preferably, the upper end of the active cantilever is connected to the first fisheye joint and the pull rod in sequence; an axial threaded opening is provided at one end of the adjustment sleeve, and the pull rod is composed of two separate first rod bodies and second rod bodies, one end of the first rod body is connected to the first fisheye joint, the other end of the first rod body is threadedly adapted to the threaded opening, one end of the second rod body is fixedly connected to the end of the adjustment sleeve, and the other end of the second rod body is connected to the second fisheye joint. The present application controls the length of the pull rod by screwing the first rod body in or out of the threaded opening of the adjustment sleeve, so that the product is flexibly applicable to beach cars and karts of various sizes, has a wide range of applications and is easy to promote.

[0007] Preferably, the mechanical transmission system is transmission-connected to a shift shaft, and the shift shaft is movably hinged inside a side engine cover on the side of the engine. The shift shaft is the driving shaft of the shift mechanism inside the engine, and returns to its original position after rotating to a corresponding angle to trigger a limit, thereby completing the shifting operation.

[0008] Preferably, the inner side surface of the side engine cover is provided with an output hole for engine output, the side engine cover is provided with a cylindrical protrusion corresponding to the output hole, the cylindrical protrusion has a built-in bearing, and the outer side of the cylindrical protrusion is provided with a plurality of radially radiating reinforcing ribs, the reinforcing ribs are fixedly connected to the inner side surface of the side engine cover and the outer surface of the cylindrical protrusion, and the reinforcing ribs are used for supporting and strengthening the cylindrical protrusion.

[0009] Preferably, the mechanical transmission system includes an active sector gear mechanism, an intermediate transmission gear mechanism, and a driven sector gear mechanism, wherein the active sector gear mechanism includes a second fisheye joint, a driven cantilever, and an active sector gear, wherein the pull rod, the second fisheye joint, the driven cantilever, and the active sector gear are sequentially connected in transmission, wherein the active sector gear is transmission-connected to an intermediate transmission gear provided in the intermediate transmission gear mechanism; wherein the driven sector gear mechanism includes a driven sector gear fixedly connected to a shift shaft, wherein the intermediate transmission gear is transmission-connected to the driven sector gear, and one end of the shift shaft is fixedly connected to the root of the driven sector gear. The mechanism adopts manual forward or backward pushing of the hand push rod, wherein forward pushing is for forward shifting, and backward pushing is for reverse shifting. The push rod mechanism is fixed on the vehicle body, and the push rod and the active cantilever connected to it rotate at the same time. The active cantilever pulls the pull rods with fisheye joints at both ends to move forward and backward, and the pull rods drive the driven cantilever to rotate at a proportional angle. While the driven cantilever rotates, the active sector gear in the engine case, that is, the side hood, rotates and drives the intermediate gear to rotate. The rotation of the intermediate gear also drives the driven sector gear to rotate. The driven sector gear and the shift shaft are welded together, and the shift shaft also rotates synchronously. After rotating to the limit angle of the corresponding gear, it automatically returns to its position to complete the gear shift.

[0010] Preferably, the driven cantilever is located on the outside of the side machine cover, and the end of the driven cantilever is hingedly provided with an outer end of a cantilever shaft. The cantilever shaft passes through the side machine cover and is fixedly connected to the center root position of the active sector gear. The cantilever shaft can rotate relative to the side machine cover, and a shaft seal for sealing is provided between the cantilever shaft and the side machine cover.

[0011] Preferably, the active sector gear, intermediate transmission gear mechanism and driven sector gear mechanism are all arranged in the side machine cover, and the intermediate transmission gear mechanism includes a positioning shaft, a limiting sleeve and the intermediate transmission gear, the positioning shaft is fixedly connected to the inner wall of the side machine cover, the intermediate transmission gear is movably sleeved on the outside of the positioning shaft, and the limiting sleeve is arranged on the outside of the intermediate transmission gear, and the limiting sleeve is used to limit the axial freedom of the intermediate transmission gear relative to the positioning shaft.

[0012] Beneficial effects: First, after changing to the right-side manual shift mechanism, the driver can shift gears like driving a family car, which is more ergonomic and more efficient. It ensures the stability of the vehicle's shifting during driving, improves the vehicle's control flexibility, and saves effort and time.

[0013] Secondly, the present application uses a unique folding rod assembly to achieve free adjustment of the angle of the folding rod assembly through the engagement of the upper joint chuck and the lower joint chuck, thereby making the setting of the push rod more flexibly adaptable to users of different body shapes and facilitating flexible gear shifting for users.

[0014] Third, the setting of the fisheye pin has two functions: first, it can be used to transmit torque, so that the upper and lower ends of the active cantilever can achieve transmission connection relative to the middle and lower ends of the push rod respectively, avoiding the situation where the push rod can only be driven by the fixed frame shaft, and improving the connection stability between the push rod and the active cantilever. Secondly, the limit flange set on the fisheye pin realizes the meshing and locking of the upper joint chuck and the lower joint chuck, preventing the upper joint chuck and the lower joint chuck from axially sliding and disengaging relative to the fisheye pin; and the cotter pin on the fisheye pin can realize the limit connection between the active cantilever and the first fisheye joint. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The structure of the embodiment is shown in FIG. Figure 1 .

[0016] Figure 2 The structure of the embodiment is shown in FIG. Figure 2 .

[0017] Figure 3 The structure of the embodiment is shown in FIG. Figure 3 .

[0018] Figure 4 The internal diagram of the embodiment Figure 1 .

[0019] Figure 5 The internal diagram of the embodiment Figure 2 .

[0020] Figure 6 The internal diagram of the embodiment Figure 3 .

[0021] Figure 7 It is a structural diagram of the bottom rod.

[0022] Figure 8 It is a schematic diagram of the structure of the top rod.

[0023] Description of the drawings: 1. right hand push rod mechanism; 101. hand push rod; 102. vehicle body fixing frame; 103. fixing frame shaft; 104. first fisheye joint; 105. pull rod; 106. adjustment sleeve; 107. cotter pin; 108. active cantilever; 109. fisheye pin shaft; 110. limit flange; 2. active sector gear mechanism; 201. second fisheye joint; 202. driven cantilever; 203. shaft seal; 204. active sector gear; 205. cantilever shaft; 3. middle Intermediate transmission gear mechanism; 301, limit sleeve; 302, intermediate transmission gear; 303, positioning shaft; 4, driven sector gear mechanism; 401, driven sector gear; 402, shift shaft; 5, side engine cover; 501, cylindrical protrusion; 502, reinforcing rib; 6, rod head; 7, bottom rod; 701, upper joint chuck; 702, polygonal gear slot; 703, shift slot; 8, top rod; 801, lower joint chuck; 802, polygonal gear block; 803, shift block. DETAILED DESCRIPTION

[0024] The following is combined with Figure 1-8 The present invention is further illustrated with examples.

[0025] Embodiment: A manual shift mechanism specifically used for a small displacement engine comprises a right-hand push rod mechanism 1 and a mechanical transmission system connected in a transmission manner. Figure 4 As shown, the mechanical transmission system is connected to a shift shaft 402, and the shift shaft 402 is movably hinged to the inside of a side hood 5 provided on the side of the engine. The shift shaft 402 is the driving shaft of the shift mechanism inside the engine, and returns to its original position after rotating to a corresponding angle to trigger a limit, completing the shifting operation.

[0026] like Figure 1-3 As shown, the right-hand push rod mechanism 1 is arranged at the head position of the vehicle body, and the right-hand push rod mechanism 1 includes a hand push rod 101, an active cantilever 108, a vehicle body fixing frame 102, an adjustment sleeve 106, a first fisheye joint 104 and a pull rod 105. The vehicle body fixing frame 102 is fixedly connected to the vehicle body, and the lower ends of the hand push rod 101 and the active cantilever 108 are fixedly connected to the same fixing frame shaft 103, and the hand push rod 101 is movably hinged to the vehicle body fixing frame 102 through the fixing frame shaft 103.

[0027] like Figure 1 As shown, the push rod 101 includes a folding rod assembly and a rod head 6 disposed at the upper end of the folding rod assembly, and the folding rod assembly is composed of a bottom rod 7 and a top rod 8 that are adapted to each other. Figure 7-8As shown, the lower end of the bottom rod 7 is fixedly connected to the radial direction of the fixed frame shaft 103, the upper end of the bottom rod 7 is provided with an upper joint chuck 701, and the upper joint chuck 701 is radially fixedly connected to the upper end of the bottom rod 7, and the upper joint chuck 701 is provided with a first circular clamping surface on the side facing away from the active cantilever 108, and a regular polygonal gear groove 702 is provided on the first circular clamping surface, the upper end of the top rod 8 is fixedly connected to the rod head 6 for hand holding, and the lower end of the top rod 8 is provided with a lower joint chuck 801, The joint chuck 801 is radially fixedly connected to the lower end of the top rod 8. The lower joint chuck 801 is provided with a second circular locking surface corresponding to the first circular locking surface. The surface of the second circular locking surface is provided with a regular polygonal shift block 802. When the regular polygonal shift block 802 and the regular polygonal shift groove 702 are mutually engaged, the relative angle between the bottom rod 7 and the top rod 8 is fixed. When the regular polygonal shift block 802 and the regular polygonal shift groove 702 are separated from each other, the bottom rod 7 and the top rod 8 can rotate relative to each other. The outer circumference of the regular polygonal shift groove 702 is uniformly distributed with a plurality of stepping grooves 703 corresponding to the outer edges of the regular polygon. The outer circumference of the regular polygonal shift block 802 is uniformly distributed with a plurality of stepping blocks 803 corresponding to the outer edges of the regular polygon. The stepping blocks 803 and the stepping groove 703 constitute a detachable locking adapter. The number of sides of the regular polygonal shift slot 702 is the same as the number of the step slots 703 , so that the bottom rod 7 and the top rod 8 can be positioned and adapted to each other regardless of the angle between them.

[0028] like Figure 1 As shown, the active cantilever 108 and the first fisheye joint 104 are movably hinged to each other through a fisheye pin 109, and the fisheye pin 109 passes through concentric pin holes provided in the upper joint chuck 701 and the lower joint chuck 801. The fisheye pin 109 is provided with a radially protruding limiting flange 110 at one end corresponding to the lower joint chuck 801, and the limiting flange 110 is used to prevent the upper joint chuck 701 and the lower joint chuck 801 from detaching from each other. The fisheye pin 109 is provided with a radial pin hole at one end corresponding to the first fisheye joint 104, and a cotter pin 107 is inserted and adapted in the pin hole. The cotter pin 107 is used to limit the relative position of the active cantilever 108 and the first fisheye joint 104.

[0029] like Figure 1As shown, the upper end of the active cantilever 108 is connected to the first fisheye joint 104 and the pull rod 105 in sequence; one end of the adjustment sleeve 106 is provided with an axial threaded opening, and the pull rod 105 is composed of two separate first rod bodies and second rod bodies, one end of the first rod body is connected to the first fisheye joint 104, the other end of the first rod body is threadedly adapted to the threaded opening, one end of the second rod body is fixedly connected to the end of the adjustment sleeve 106, and the other end of the second rod body is connected to the second fisheye joint 201. The present application controls the length of the pull rod 105 by screwing the first rod body in or out of the threaded opening of the adjustment sleeve 106, so that the product is flexibly applicable to beach cars and karts of various sizes, with a wide range of applications and easy to promote.

[0030] like Figure 6 As shown, the inner side surface of the side engine cover 5 is provided with an output hole for engine output, and the side engine cover 5 is provided with a cylindrical protrusion 501 corresponding to the output hole. The cylindrical protrusion 501 has a built-in bearing, and the outer side of the cylindrical protrusion 501 is provided with a plurality of radially radiating reinforcing ribs 502. The reinforcing ribs 502 are fixedly connected to the inner side surface of the side engine cover 5 and the outer surface of the cylindrical protrusion 501, and the reinforcing ribs 502 are used for supporting and reinforcing the cylindrical protrusion 501.

[0031] like Figure 4-5As shown, the mechanical transmission system includes an active sector gear mechanism 2, an intermediate transmission gear mechanism 3, and a driven sector gear mechanism 4. The active sector gear mechanism 2 includes a second fisheye joint 201, a driven cantilever 202, and an active sector gear 204. The pull rod 105, the second fisheye joint 201, the driven cantilever 202, and the active sector gear 204 are sequentially connected in transmission. The active sector gear 204 is connected in transmission to an intermediate transmission gear 302 provided in the intermediate transmission gear mechanism 3. The driven sector gear mechanism 4 includes a driven sector gear 401 fixedly connected to a shift shaft 402. The intermediate transmission gear 302 is connected in transmission to the driven sector gear 401. One end of the shift shaft 402 is fixedly connected to the root of the driven sector gear 401. This mechanism uses a manual push rod 101 to push forward or backward. Pushing forward is for forward shifting, and pushing backward is for reverse shifting. The push rod 101 mechanism is fixed on the vehicle body, and the push rod 101 and the active cantilever 108 connected to it rotate at the same time. The active cantilever 108 pulls the pull rod 105 with fisheye joints at both ends to move forward and backward, and the pull rod 105 drives the driven cantilever 202 to rotate at a proportional angle. While the driven cantilever 202 rotates, the active sector gear 204 in the engine case, that is, the side engine cover 5, rotates and drives the intermediate gear to rotate. The rotation of the intermediate gear also drives the driven sector gear 401 to rotate. The driven sector gear 401 and the shift shaft 402 are welded together, and the shift shaft 402 also rotates synchronously. After rotating to the limit angle of the corresponding gear, it automatically returns to its position to complete the gear shift. The driven cantilever 202 is located outside the side cover 5, and the end of the driven cantilever 202 is hinged with the outer end of the cantilever shaft 205, and the cantilever shaft 205 passes through the side cover 5 and is fixedly connected to the center root position of the active sector gear 204. The cantilever shaft 205 can rotate relative to the side cover 5, and a shaft seal 203 for sealing is provided between the cantilever shaft 205 and the side cover 5. The active sector gear 204, the intermediate transmission gear mechanism 3 and the driven sector gear mechanism 4 are all arranged in the side cover 5, and the intermediate transmission gear mechanism 3 includes a positioning shaft 303, a limiting sleeve 301 and the intermediate transmission gear 302, the positioning shaft 303 is fixedly connected to the inner wall of the side cover 5, the intermediate transmission gear 302 is movably sleeved outside the positioning shaft 303, and the limiting sleeve 301 is arranged outside the intermediate transmission gear 302, and the limiting sleeve 301 is used to limit the axial freedom of the intermediate transmission gear 302 relative to the positioning shaft 303.

[0032] Operation principle: When shifting is required, push the push rod 101 with the right hand, push forward for forward shifting, push backward for reverse shifting. Since the active cantilever 108 and the push rod 101 are integrated, the active cantilever 108 rotates with the rotation of the push rod 101, pulling the pull rod 105 connected to the active cantilever 108 to move, thereby pulling the driven cantilever 202 to change the angle and rotate. The driven cantilever 202 is fixed as a whole with the active sector gear 204, so the active sector gear 204 starts to rotate, and the active sector gear 204 drives the intermediate transmission gear 302 meshing with it to rotate. The intermediate gear drives the driven sector gear 401 to rotate. Since the driven sector gear 401 and the shift shaft 402 are integrated, the shift shaft 402 also rotates. The shift shaft 402 is the drive shaft of the shift mechanism inside the engine. When the corresponding angle of rotation triggers the limit, it returns to its original position, completing the shifting work.

[0033] Obviously, the above embodiments of the present invention are merely examples for illustrating the present invention, and are not intended to limit the implementation methods of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to exhaust all implementation methods here. However, these obvious changes or modifications derived from the essential spirit of the present invention still fall within the protection scope of the present invention.

Claims

1. A manual shift mechanism specifically for small displacement engines, characterized in that: The invention comprises a right-hand push rod mechanism (1) and a mechanical transmission system connected in a transmission manner. The right-hand push rod mechanism (1) is arranged at the head position of a vehicle body. The right-hand push rod mechanism (1) comprises a hand push rod (101), an active cantilever (108), a vehicle body fixing frame (102), an adjustment sleeve (106), a first fisheye joint (104) and a pull rod (105). The lower ends of the hand push rod (101) and the active cantilever (108) are fixedly connected to the same fixing frame shaft (103). The hand push rod (101) is movably hinged to the vehicle body fixing frame (102) through the fixing frame shaft (103). The vehicle body fixing frame (102) is fixedly connected to the vehicle body. The push rod (101) comprises a folding rod assembly, which is composed of a bottom rod (7) and a top rod (8) adapted to each other. The bottom rod (7) has a lower end fixedly connected to the radial direction of a fixed frame shaft (103). The upper end of the bottom rod (7) is provided with an upper joint chuck (701), which is radially fixedly connected to the upper end of the bottom rod (7). The upper joint chuck (701) is provided with a regular polygonal gear slot (702) on the side of the upper joint chuck (701) facing away from the active cantilever (108). The lower end of the top rod (8) is provided with a lower joint chuck (801). ), the lower joint chuck (801) is radially fixedly connected to the lower end of the top rod (8), and the lower joint chuck (801) is provided with a regular polygonal gear block (802) adapted to the regular polygonal gear slot (702); when the regular polygonal gear block (802) and the regular polygonal gear slot (702) are mutually engaged, the relative angle between the bottom rod (7) and the top rod (8) is fixed; when the regular polygonal gear block (802) and the regular polygonal gear slot (702) are disengaged from each other, the bottom rod (7) and the top rod (8) can rotate relative to each other.

2. A manual shift mechanism specifically for a small displacement engine according to claim 1, characterized in that: The active cantilever (108) and the first fisheye joint (104) are movably hinged to each other via a fisheye pin shaft (109). The fisheye pin shaft (109) passes through concentric pin holes provided on the upper joint chuck (701) and the lower joint chuck (801). The fisheye pin shaft (109) is provided with a radially protruding limiting flange (110) at one end corresponding to the lower joint chuck (801). The limiting flange (110) is used to prevent the upper joint chuck (701) and the lower joint chuck (801) from detaching from each other. The fisheye pin shaft (109) is provided with a radial pin hole at one end corresponding to the first fisheye joint (104). A cotter pin (107) is inserted and adapted in the pin hole. The cotter pin (107) is used to limit the relative position of the active cantilever (108) and the first fisheye joint (104).

3. A manual shift mechanism specifically for a small displacement engine according to claim 1, characterized in that: The outer circumference of the regular polygonal shift groove (702) is evenly distributed with a plurality of stepping grooves (703) corresponding to the outer edges of the regular polygon; the outer circumference of the regular polygonal shift block (802) is evenly distributed with a plurality of stepping blocks (803) corresponding to the outer edges of the regular polygon; the stepping blocks (803) and the stepping grooves (703) form a detachable card-type card-type adapter.

4. A manual shift mechanism specifically for a small displacement engine according to claim 1, characterized in that: The upper end of the active cantilever (108) is connected to the first fisheye joint (104) and the pull rod (105) in sequence; one end of the adjustment sleeve (106) is provided with an axial threaded opening, and the pull rod (105) is composed of two separate first rod bodies and a second rod body, one end of the first rod body is connected to the first fisheye joint (104), and the other end of the first rod body is threadedly adapted to the threaded opening, one end of the second rod body is fixedly connected to the end of the adjustment sleeve (106), and the other end of the second rod body is connected to the second fisheye joint (201).

5. A manual shift mechanism specifically for a small displacement engine according to claim 1, characterized in that: The mechanical transmission system is connected to a shift shaft (402) which is movably hinged inside a side engine cover (5) on the side of the engine. The shift shaft (402) is a drive shaft of a shift mechanism inside the engine. When the corresponding angle is rotated to trigger a limit, the shift shaft returns to its original position, completing the shifting operation.

6. A manual shift mechanism specifically for a small displacement engine according to claim 5, characterized in that: The inner side surface of the side engine cover (5) is provided with an output hole for engine output, the side engine cover (5) is provided with a cylindrical protrusion (501) corresponding to the output hole, the cylindrical protrusion (501) has a built-in bearing, and the outer side of the cylindrical protrusion (501) is provided with a plurality of radially radiating reinforcing ribs (502), the reinforcing ribs (502) are fixedly connected to the inner side surface of the side engine cover (5) and the outer surface of the cylindrical protrusion (501), and the reinforcing ribs (502) are used to support and strengthen the cylindrical protrusion (501).

7. A manual shift mechanism specifically for a small displacement engine according to claim 6, characterized in that: The mechanical transmission system comprises an active sector gear mechanism (2), an intermediate transmission gear mechanism (3), and a driven sector gear mechanism (4); the active sector gear mechanism (2) comprises a second fisheye joint (201), a driven cantilever (202), and an active sector gear (204); the pull rod (105), the second fisheye joint (201), the driven cantilever (202), and the active sector gear (204) are sequentially transmission-connected; the active sector gear (204) is transmission-connected to an intermediate transmission gear (302) provided in the intermediate transmission gear mechanism (3); the driven sector gear mechanism (4) comprises a driven sector gear (401) fixedly connected to a shift shaft (402); the intermediate transmission gear (302) is transmission-connected to the driven sector gear (401); and one end of the shift shaft (402) is fixedly connected to the root of the driven sector gear (401).

8. A manual shift mechanism specifically for a small displacement engine according to claim 7, characterized in that: The driven cantilever (202) is located outside the side cover (5), and the end of the driven cantilever (202) is hingedly provided with an outer end of a cantilever shaft (205). The cantilever shaft (205) passes through the side cover (5) and is fixedly connected to the center root position of the active sector gear (204). The cantilever shaft (205) can be rotatable relative to the side cover (5), and a shaft seal (203) for sealing is provided between the cantilever shaft (205) and the side cover (5).

9. A manual shift mechanism specifically for a small displacement engine according to claim 8, characterized in that: The active sector gear (204), the intermediate transmission gear mechanism (3) and the driven sector gear mechanism (4) are all arranged in the side cover (5); the intermediate transmission gear mechanism (3) comprises a positioning shaft (303), a limiting sleeve (301) and the intermediate transmission gear (302); the positioning shaft (303) is fixedly connected to the inner wall of the side cover (5); the intermediate transmission gear (302) is movably sleeved on the outside of the positioning shaft (303); the limiting sleeve (301) is arranged on the outside of the intermediate transmission gear (302); and the limiting sleeve (301) is used to limit the axial freedom of the intermediate transmission gear (302) relative to the positioning shaft (303).

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