Speed control system

Abstract

The invention discloses a speed control system. Comprising a base; the input unit comprises an input shaft arranged on the base and an input gear arranged on the input shaft, and the input shaft is in transmission connection with the power source; the output unit comprises a first output gear rotationally arranged on the base, a gear set in transmission connection with the first output gear and a second output gear in transmission connection with the gear set, and the second output gear outputs power through an output shaft; the input gear is shifted through shifting of the shifting fork so that the input gear can be in transmission connection with the first output gear, any gear unit and the second output gear. Gear shifting can be achieved by pushing the input gear to transversely move to the corresponding output gear through the shifting fork, gear shifting is smooth, response is rapid, torque is high, the lower output unit is matched with a newly-designed special-shaped gear structure, the structure is simpler and more compact, cost is low, maintenance is convenient, and the service life is long.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle speed change systems, in particular to a speed change system. Background Art

[0002] Sequential Manual Gearbox (SMG) is the full name of sequential manual gearbox. It is different from ordinary manual gearbox only in operation method. Upshifting and downshifting can be completed by pushing and pulling the gear lever forward and backward. This design not only speeds up the gear shifting speed, but also greatly reduces the possibility of shifting the wrong gear.

[0003] A conventional sequential gearbox, such as the patent document CN221120799U, has an input shaft and an output shaft, each of which has a plurality of gears whose axes are aligned with their respective axes. The gears are of different sizes and shapes. Some gears have spline teeth inside that can mesh with the splines on the shaft and slide left and right. Another part of the gears is fixed to the shaft by needle rollers to ensure that it does not slide left and right while idling. The idling gears have grooves on their sides to ensure that the dog teeth on the spline gears can slide into the grooves and engage with each other.

[0004] When in working state, the spline gear slides to the corresponding idle gear and locks it, so that the output shaft rotates with this gear and transmits power. For different gears, different spline teeth and different idle gears need to cooperate with each other. At the same time, in practical applications, a ratchet with several grooves is often required. The increase and decrease of gears is to rotate the ratchet. When the ratchet rotates, the shift mechanism stuck in the groove will move. The ratchet is used to control multiple sets of shift forks at the same time, and to engage another set of gears while one set of gears is separated, so as to achieve the effect of almost no shift gap.

[0005] The advantages of this design are smaller size, faster shifting time and better transmission efficiency, but its disadvantages are also obvious: During the gear shifting process, it cannot jump gears like other transmissions, but can only gradually increase or decrease gears; the noise is extremely loud, and the special design of the dog-tooth clutch makes the transmission not durable; the gear shifting is uncomfortable and frustrating, so it is often only suitable for racing cars.

[0006] To this end, the applicant proposed this application, aiming to eliminate the disadvantages of the sequential gearbox while retaining its advantages. Summary of the invention

[0007] In view of the deficiencies in the prior art, the present invention provides a transmission system, which can achieve gear shifting by pushing the input gear to move horizontally to the corresponding output gear through a shift fork. The gear shifting is smooth, responsive and has high torque. A newly designed special-shaped gear structure is used at the lower output unit. The structure is simpler, low-cost, easy to maintain and compact. It has the advantages of a sequential gearbox while eliminating its disadvantages.

[0008] In order to solve the above technical problems, the present invention is solved by the following technical solutions: A speed change system comprising Pedestal; An input unit, comprising an input shaft disposed on the base and rotatable relative to the base and an input gear disposed on the input shaft and movably disposed on the input shaft and rotatable synchronously therewith, wherein the input shaft is drivingly connected to a power source; and An output unit, comprising a first output gear rotatably disposed on the base, a gear set transmission-connected to the first output gear, and a second output gear transmission-connected to the gear set, wherein the second output gear outputs power through an output shaft; The gear set includes a plurality of gear units that are sequentially connected in transmission to form a gear layout in which the diameters of the first output gear, the plurality of gear units and the second output gear decrease sequentially; The input gear is shifted by a shift fork so that it can be drivingly connected with the first output gear, any of the gear units and the second output gear.

[0009] In the above technical solution, preferably, the first output gear is provided with a first transmission tooth that rotates synchronously therewith, all the gear units include a main gear, a first internal tooth portion provided on the main gear, and a second transmission tooth that rotates synchronously with the main gear, and the second output gear includes a second internal tooth portion; The first output gear and the adjacent gear unit are connected to each other through the cooperation of the first transmission teeth and the first internal gear portion to form a transmission connection; Two adjacent gear units are connected to each other through the cooperation between the second transmission teeth and the corresponding first internal teeth. The second output gear and the adjacent gear unit are connected in transmission connection through the cooperation between the second transmission teeth and the second inner gear portion.

[0010] In the above technical solution, preferably, the teeth on the first transmission tooth, the first internal tooth portion, the second transmission tooth and the second internal tooth portion are straight teeth or helical teeth.

[0011] In the above technical solution, preferably, a first support seat is arranged on the base, a first extension shaft is laterally extended on the first output gear and penetrates the first support seat, the first transmission tooth is arranged at the outer end of the first extension shaft, and a one-way bearing is arranged between the first support seat and the first extension shaft.

[0012] In the above technical solution, preferably, the base is provided with a second support seat for supporting the gear unit, the main gear is laterally extended with a second extension shaft passing through the second support seat, and the second transmission tooth is arranged at the outer end of the second extension shaft.

[0013] In the above technical solution, preferably, a one-way bearing is arranged between the second support seat and the second extension shaft; A first circular inner concave cavity concentric with the main gear is formed on the side wall of the main gear, and the first inner tooth portion is arranged on the circular side wall of the first circular inner concave cavity; A second circular inner concave cavity concentric with the second output gear is formed on the side wall of the second output gear, and the second inner tooth portion is arranged on the circular side wall of the second circular inner concave cavity.

[0014] In the above technical solution, preferably, the first output gear is concentric with the first extension shaft and the first transmission tooth; The outer diameter of the main gear gradually decreases from close to the first output gear to away from it. The main gear, the second extension shaft, and the second transmission tooth on the same gear unit are concentric. The second extension shaft is concentric with the corresponding mounting hole on the second support seat, so that the center heights of the mounting holes of the second support seats matched with different gear units are different.

[0015] In the above technical solution, preferably, a support shaft is arranged on the base, and a plurality of support gears meshing with the main gear of the gear unit are arranged on the support shaft.

[0016] In the above technical solution, preferably, two groups of the support shafts are configured on the base, which are respectively arranged on the front side and the rear side of the gear unit; The number of the supporting gears is consistent with the number of the main gears; A first circular inner concave cavity concentric with the main gear is formed on the side wall of the main gear, and the first inner tooth portion is arranged on the circular side wall of the first circular inner concave cavity; A second circular inner cavity concentric with the second output gear is formed on the side wall thereof, and the second inner tooth portion is arranged on the circular side wall of the second circular inner cavity; The first transmission tooth is formed on the side wall of the first output gear, and its thickness is adapted to the depth of the corresponding first circular inner cavity to reduce the gap between the first output gear and the adjacent gear unit; The second transmission tooth is formed on the side wall of the main gear, and its thickness is adapted to the depth of the corresponding first circular inner cavity to reduce the gap between two adjacent gear units; The depth of the second circular inner cavity is matched with the thickness of the corresponding second transmission tooth to reduce the gap between the gear unit and the second output gear.

[0017] In the above technical solution, preferably, the input gear is located above the first output gear, all the gear units and the second output gear; The upper edges of the first output gear, all the gear units and the second output gear are flush with each other; The base is provided with a connecting shaft, and the first output gear is rotatable relative to the base through the connecting shaft; The horizontal position of the output shaft is higher than the horizontal position of the connecting shaft.

[0018] The beneficial effects of the present invention are: The invention can realize gear shifting by pushing the input gear to move horizontally to the corresponding output gear through the shift fork, and the gear shifting is smooth, the response is rapid, and the torque is high. The output unit below adopts a newly designed special-shaped gear structure to cooperate, which is simpler and more compact, low in cost, easy to maintain, and has a long service life. The design of the support seat or support gear can ensure the transmission stability of the transmission gear in the middle part, and the design of the helical gear helps to reduce noise. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of Example 1 of the present invention.

[0020] Figure 2 It is a top view schematic diagram of embodiment 1 of the present invention.

[0021] Figure 3 This is a cross-sectional schematic diagram of Example 1 of the present invention.

[0022] Figure 4 This is a schematic diagram of the first output gear of Example 1 of the present invention.

[0023] Figure 5 Schematic diagram of the gear unit according to embodiment 1 of the present invention.

[0024] Figure 6 This is a schematic diagram of the second output gear of Example 1 of the present invention.

[0025] Figure 7 This is a schematic diagram of a support base according to Embodiment 1 of the present invention.

[0026] Figure 8 This is a schematic diagram of Example 2 of the present invention.

[0027] Fig. 9 It is a top view schematic diagram of embodiment 2 of the present invention.

[0028] Fig.10 It is a cross-sectional schematic diagram of embodiment 2 of the present invention.

[0029] Fig.11 This is a schematic diagram of the first output gear of Example 2 of the present invention.

[0030] Fig.12 Schematic diagram of the gear unit according to embodiment 2 of the present invention.

[0031] Fig.13 This is a schematic diagram of the second output gear of Example 2 of the present invention.

[0032] Fig.14 It is a schematic diagram of the matching state of the support shaft and the support gear in embodiment 2 of the present invention. DETAILED DESCRIPTION

[0033] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments: Example 1

[0034] See also Figure 1-Figure 7 A speed change system includes a base 1, on which an input unit and an output unit are arranged. The base 1 serves as a load-bearing component and can be a shell-like component or a component that only supports the end of a related shaft. When it is a shell-like component, it can include a cover for accommodating a related transmission structure.

[0035] like Figure 1 The style shown is one embodiment of the base, which includes a bottom plate 11 and at least two vertical plates 12 fixedly mounted on or integrally formed on the bottom plate 11. Figure 1 The illustrated embodiment shows that four vertical plates 12 are provided.

[0036] The input unit includes an input shaft 21 and an input gear 22, wherein the input shaft 21 is connected to the power source by transmission, wherein the input shaft 21 is assembled on the base 1. As one embodiment, the input shaft 21 is passed through the vertical plate 12, such as passed through more than two vertical plates 12, and supported by multiple vertical plates 12. At the same time, the input shaft 21 can also rotate relative to the vertical plate 12, such as directly passing the input shaft 21 through the vertical plate 12.

[0037] The input gear 22 is assembled on the input shaft 21. It can move laterally on the input shaft 21 and rotate synchronously with the input shaft 21. The lateral movement of the input gear 22 depends on the shift fork (not shown in the figure). For the shift fork, please refer to the existing design.

[0038] As for the connection method between the input shaft 21 and the input gear 22, as one of the implementation methods, the input shaft 21 is key-connected with the input gear 22, and the outer wall of the input shaft 21 has a plurality of axially extending key strips, and the inner hole wall of the input gear 22 has a groove body that matches the key strips. If the outer wall of the input shaft 21 is circumferentially evenly covered with key strips, the groove bodies are also circumferentially evenly covered on the inner hole wall of the input gear 22. In this form, the inner hole wall of the input gear 22 presents an inner gear ring shape.

[0039] As for the output unit, it includes a first output gear 3, a gear set and a second output gear 4, wherein the gear set is transmission-connected to the first output gear 3, and includes a plurality of gear units 5 transmission-connected in sequence. As one embodiment, the output unit is arranged as a whole below the input unit, and is arranged in sequence by the first output gear 3, a plurality of gear units 5 and the second output gear 4, corresponding to a plurality of gears. When the input gear 22 is transmission-connected to the first output gear 3, it corresponds to the first gear; when the input gear 22 is transmission-connected to the gear unit 5 on the side of the first output gear 3, it corresponds to the second gear; and so on until the input gear 22 is transmission-connected to the second output gear 4, it corresponds to the last gear. If three gear units 5 are provided, the gear is the fifth gear; if four gear units 5 are provided, the gear is the sixth gear, and so on.

[0040] The first output gear 3 is arranged on the base 1. If a connecting shaft 31 is provided on the corresponding vertical plate 12, the first output gear 3 can be rotated relative to the vertical plate 12 through the connecting shaft 31. The first output gear 3 can be fixedly connected to the connecting shaft 31, and the connecting shaft 31 is rotatably provided on the vertical plate 12; or the connecting shaft 31 is fixedly provided on the vertical plate 12, and the first output gear 3 is rotatably provided on the connecting shaft 31.

[0041] In this embodiment, the first output gear 3 is provided with a first transmission tooth 32 which rotates synchronously therewith. Figure 4 As shown, a first extension shaft 33 extends laterally on the side wall of the first output gear 3, and a first transmission tooth 32 is arranged at the outer end of the first extension shaft 33 so that the first transmission tooth 32 rotates synchronously with the first output gear 3, wherein the first output gear 3, the first extension shaft 33 and the first transmission tooth 32 can be welded and fixed to each other or integrally formed.

[0042] In this embodiment, the first output gear 3 is concentrically disposed with the first extension shaft 33 and the first transmission gear 32 .

[0043] like Figure 1-3 As shown, a first support seat 6 is installed on the bottom plate 11, and the installation method can be welding fixation or fixing by fasteners, etc. The first support seat 6 includes a through hole, and the first extension shaft 33 is arranged at the through hole. When the first output gear 3, the first extension shaft 33 and the first transmission tooth 32 are integrally formed, the upper end of the first support seat 6 can be designed to be expandable, such as its upper end is rotatably connected to its main body, and then locked by fasteners, etc. After opening its upper end, the first extension shaft 33 can be assembled to the through hole; when the first output gear 3, the first extension shaft 33 and the first transmission tooth 32 are welded and fixed, etc., after the first extension shaft 33 passes through the through hole, the first transmission tooth 32 can be fixed on the first extension shaft 33.

[0044] In this embodiment, a one-way bearing 61 is provided between the first extension shaft 33 and the perforated wall of the first support seat 6, the outer ring of the one-way bearing 61 is adapted to the aperture of the perforation, and the inner ring of the one-way bearing 61 is adapted to the outer diameter of the first extension shaft 33. The one-way bearing 61 can be used to prevent the problem of jamming during gear shifting, which is mainly attributed to the situation that the speeds of different gears are inconsistent during gear shifting, and the one-way bearing can effectively solve this technical problem.

[0045] The gear unit 5 includes a main gear 51, a first inner gear portion 52 and a second transmission gear 53, wherein the first inner gear portion 52 is disposed on the main gear 51. As one embodiment, Figure 5 As shown, a first circular inner cavity 54 concentric with the main gear 51 is opened on the side wall thereof, a first inner tooth portion 52 is arranged on the circular side wall of the first circular inner cavity 54, and the first inner tooth portion 52 of the gear unit 5 adjacent to the first output gear 3 is transmission-connected with the first transmission tooth 32, as shown in FIG. Figure 3 As shown, the first transmission teeth 32 are arranged at the lower part of the first circular inner cavity 54 and mesh with the teeth at the lower part of the first inner tooth portion 52 , so that the gear unit 5 and the first output gear 3 form a transmission connection relationship.

[0046] like Figure 5 As shown, a second extension shaft 55 extends laterally on the side wall of the main gear 51, and the second transmission tooth 53 is arranged at the outer end of the second extension shaft 55 so that the second transmission tooth 53 and the main gear 51 rotate synchronously, wherein the main gear 51, the second extension shaft 55 and the second transmission tooth 53 can be welded and fixed to each other or integrally formed.

[0047] like Figure 1-3 As shown, a second support seat 62 is installed on the base plate 11, and the installation method can be welding fixation or fixation through fasteners, etc. The second support seat 62 is used to support the gear unit 5. As one embodiment, the second support seat 62 has the same structure as the first support seat 6.

[0048] The second support seat 62 includes a through hole, and the second extension shaft 55 is inserted into the through hole. When the main gear 51, the second extension shaft 55 and the second transmission tooth 53 are integrally formed, the upper end of the second support seat 62 can be designed to be expandable, such as its upper end is rotatably connected to its main body, and then locked by fasteners, etc. After opening its upper end, the second extension shaft 55 can be assembled to the through hole; when the main gear 51, the second extension shaft 55 and the second transmission tooth 53 are fixed by welding, etc., the second transmission tooth 53 can be fixed on the second extension shaft 55 after the second extension shaft 55 passes through the through hole.

[0049] In this embodiment, a one-way bearing 61 is arranged between the second extension shaft 55 and the perforated wall of the second support seat 62. The outer ring of the one-way bearing 61 is adapted to the aperture of the perforation, and the inner ring of the one-way bearing 61 is adapted to the outer diameter of the second extension shaft 55. The function of the one-way bearing is the same as that of the one-way bearing on the first support seat 6.

[0050] like Figure 1 , Figure 2 As shown, a plurality of gear units 5 are arranged in sequence, and each gear unit 5 is provided with a corresponding second support seat 62. Adjacent gear units 5 are connected to each other through the cooperation of the second transmission teeth 53 and the corresponding first inner teeth 52 to form a transmission connection. Figure 3 As shown, the second transmission teeth 53 are arranged at the lower part of the corresponding first circular inner concave cavity 54 and mesh with the teeth at the lower part of the corresponding first inner tooth portion 52 .

[0051] In this embodiment, the outer diameter of the main gear 51 gradually decreases from close to the first output gear 3 to away from it, that is, the diameter of the first output gear 3 is the largest, and the diameter gradually decreases toward the second output gear 4, but the upper edges of the first output gear 3, the main gears 51 of all gear units 5 and the second output gear 4 are flush, so that the input gear 22 only needs to move laterally to engage with any of the above gears to switch to different gears.

[0052] In this embodiment, the main gear 51, the second extension shaft 55 and the second transmission tooth 53 on the same gear unit 5 are concentric, and the second extension shaft 55 is concentric with the through hole on the corresponding second support seat 62, so that the center heights of the mounting holes of the second support seats 62 matched with different gear units 5 are different, such as Figure 3 shown.

[0053] The second output gear 4 is connected to the gear set in transmission, specifically, Figure 6As shown, a second circular inner concave cavity 41 concentric with the second output gear 4 is provided on the side wall thereof, a second inner tooth portion 42 is provided on the circular side wall of the second circular inner concave cavity 41, and a second transmission tooth 53 of the gear unit 5 adjacent to the second output gear 4 is transmission-connected with the second inner tooth portion 42. For example, the second transmission tooth 53 is arranged at the lower part of the second circular inner concave cavity 41 and meshes with the teeth at the lower part of the second inner tooth portion 42, so that the second output gear 4 and the gear unit 5 form a transmission connection relationship, as shown in FIG. Figure 3 shown.

[0054] In this embodiment, Figure 1-Figure 3 , Figure 6 As shown, the outer wall of the second output gear 4 is connected to an output shaft 43 that rotates synchronously therewith. The output shaft 43 is rotatably installed on the corresponding vertical plate 12 to output power through the output shaft 43. The output shaft 43 and the second output gear 4 can be welded or integrally formed.

[0055] In this embodiment, the teeth on the first transmission tooth 32, the first inner tooth portion 52, the second transmission tooth 53 and the second inner tooth portion 42 are straight teeth or helical teeth, preferably helical teeth, which can further reduce the noise generated during transmission action.

[0056] In this embodiment, Figure 3 As shown, the horizontal position of the output shaft 43 is higher than the horizontal position of the connecting shaft 31 .

[0057] The input power is inputted by the input shaft 21 which is connected to the power source, driving the input gear 22 to rotate. When the input gear 22 is connected to the first output gear 3, it is the first gear. While the first output gear 3 rotates, all the gear units 5 and the second output gear 4 rotate synchronously, and finally the power is outputted through the output shaft 43. When the input gear 22 is connected to any main gear 51 or the second output gear 4, it is the other gears. The first gear torque of the first output gear 3 is the largest, and the gear increases and the torque decreases successively toward the second output gear 4. When the input gear 22 is not connected to the first output gear 3, any main gear 51 and the second output gear 4, it is neutral. Example 2

[0058] The main difference between this embodiment and Embodiment 1 is that the supporting method of the gear unit 5 is different, and the rest are the same. For the description of the same parts, reference can be made directly to Embodiment 1.

[0059] like Figure 8-Figure 14As shown, a support shaft 71 is arranged on the vertical plate 12 of the base 1, and a plurality of support gears 72 meshing with the main gear 51 of the gear unit 5 are arranged on the support shaft 71. When the main gear 51 rotates, the support gear 72 can rotate accordingly. The support gear 72 can be rotatably arranged on the support shaft 71. The diameter of the support gear 72 is determined according to the size of the corresponding main gear 51. If the corresponding main gear 51 is larger, the corresponding support gear 72 is smaller. The layout is as follows: Figure 8 , Fig. 9 , Fig.14 shown.

[0060] As one embodiment, two sets of support shafts 71 are disposed on the vertical plate 12 of the base 1, and are arranged at the front and rear sides of the gear unit 5, respectively. Fig. 9 as shown to enhance the support effect.

[0061] In this embodiment, the number of the supporting gears 72 on one side is consistent with the number of the main gears 51 , ensuring that each main gear 51 can be effectively supported.

[0062] Due to the different support method of the gear unit 5, this embodiment is different from the embodiment 1. The spacing between the first output gear 3 and the adjacent gear unit 5, between two adjacent gear units 5, and between the second output gear 4 and the adjacent gear unit 5 can be greatly reduced, the overall structure is more compact, and the shifting speed is faster. Figure 8-Figure 10 shown.

[0063] Specifically, Fig.10 , Fig.11 As shown, the first transmission tooth 32 is formed on the side wall of the first output gear 3, and the first extension shaft 33 is no longer provided. The thickness of the first transmission tooth 32 is adapted to the depth of the corresponding first circular inner cavity 54 to reduce the gap between the first output gear 3 and the adjacent gear unit 5.

[0064] like Fig.10 , Fig.12 As shown, the second transmission teeth 53 are formed on the side wall of the main gear 51 , and the second extension shaft 55 is no longer provided. The thickness of the second transmission teeth 53 is adapted to the depth of the corresponding first circular inner cavity 54 to reduce the gap between two adjacent gear units 5 .

[0065] like Fig.10 , Fig.13 As shown, the depth of the second circular inner cavity 41 is matched with the thickness of the corresponding second transmission tooth 53 to reduce the gap between the gear unit 5 and the second output gear 4 .

[0066] In this embodiment, similar to the one-way bearings 61 provided on the first support seat 6 and the second support seat 62 in Embodiment 1, one-way bearings are provided at corresponding positions, such as between the support gear 72 and the support shaft 71 .

[0067] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A speed change system, characterized in that: include Pedestal; An input unit, comprising an input shaft disposed on the base and rotatable relative to the base and an input gear disposed on the input shaft and movably disposed on the input shaft and rotatable synchronously therewith, wherein the input shaft is drivingly connected to a power source; as well as An output unit, comprising a first output gear rotatably disposed on the base, a gear set transmission-connected to the first output gear, and a second output gear transmission-connected to the gear set, wherein the second output gear outputs power through an output shaft; The gear set includes a plurality of gear units that are sequentially connected to form a gear layout with diameters decreasing sequentially from the first output gear, the plurality of gear units to the second output gear; The input gear is shifted by a shift fork so that it can be drivingly connected with the first output gear, any of the gear units and the second output gear.

2. A speed change system according to claim 1, characterized in that: The first output gear is provided with a first transmission tooth that rotates synchronously therewith, all the gear units include a main gear, a first internal tooth portion provided on the main gear, and a second transmission tooth that rotates synchronously with the main gear, and the second output gear includes a second internal tooth portion; The first output gear and the adjacent gear unit are connected to each other through the cooperation of the first transmission teeth and the first internal gear portion to form a transmission connection; Two adjacent gear units are connected to each other through the cooperation between the second transmission teeth and the corresponding first internal teeth. The second output gear and the adjacent gear unit are connected in transmission connection through the cooperation between the second transmission teeth and the second inner gear portion.

3. A speed change system according to claim 2, characterized in that: The teeth on the first transmission tooth, the first internal tooth portion, the second transmission tooth and the second internal tooth portion are straight teeth or helical teeth.

4. A speed change system according to claim 2, characterized in that: A first support seat is arranged on the base, a first extension shaft is horizontally extended on the first output gear and penetrates the first support seat, the first transmission tooth is arranged on the outer end of the first extension shaft, and a one-way bearing is arranged between the first support seat and the first extension shaft.

5. A speed change system according to any one of claims 2 to 4, characterized in that: The base is provided with a second support seat for supporting the gear unit, the main gear is laterally extended with a second extension shaft penetrating the second support seat, and the second transmission tooth is arranged at the outer end of the second extension shaft.

6. A speed change system according to claim 5, characterized in that: A one-way bearing is arranged between the second support seat and the second extension shaft; A first circular inner concave cavity concentric with the main gear is formed on the side wall of the main gear, and the first inner tooth portion is arranged on the circular side wall of the first circular inner concave cavity; A second circular inner concave cavity concentric with the second output gear is formed on the side wall of the second output gear, and the second inner tooth portion is arranged on the circular side wall of the second circular inner concave cavity.

7. A speed change system according to claim 5, characterized in that: The first output gear is concentric with the first extension shaft and the first transmission tooth; The outer diameter of the main gear gradually decreases from close to the first output gear to away from it. The main gear, the second extension shaft, and the second transmission tooth on the same gear unit are concentric. The second extension shaft is concentric with the corresponding mounting hole on the second support seat, so that the center heights of the mounting holes of the second support seats matched with different gear units are different.

8. A speed change system according to claim 2 or 3, characterized in that: A support shaft is arranged on the base, and a plurality of support gears meshing with the main gear of the gear unit are arranged on the support shaft.

9. A speed change system according to claim 8, characterized in that: The base is provided with two sets of support shafts, which are arranged at the front side and the rear side of the gear unit respectively; The number of the supporting gears is consistent with the number of the main gears; A first circular inner concave cavity concentric with the main gear is formed on the side wall of the main gear, and the first inner tooth portion is arranged on the circular side wall of the first circular inner concave cavity; A second circular inner cavity concentric with the second output gear is formed on the side wall thereof, and the second inner tooth portion is arranged on the circular side wall of the second circular inner cavity; The first transmission tooth is formed on the side wall of the first output gear, and its thickness is adapted to the depth of the corresponding first circular inner cavity to reduce the gap between the first output gear and the adjacent gear unit; The second transmission tooth is formed on the side wall of the main gear, and its thickness is adapted to the depth of the corresponding first circular inner cavity to reduce the gap between two adjacent gear units; The depth of the second circular inner cavity is matched with the thickness of the corresponding second transmission tooth to reduce the gap between the gear unit and the second output gear.

10. A speed change system according to claim 1, characterized in that: The input gear is located above the first output gear, all the gear units and the second output gear; The upper edges of the first output gear, all the gear units and the second output gear are flush with each other; The base is provided with a connecting shaft, and the first output gear is rotatable relative to the base through the connecting shaft; The horizontal position of the output shaft is higher than the horizontal position of the connecting shaft.

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