Mid-speed transmission system and bicycle

Abstract

The present invention relates to the technical field of transmission systems, and discloses a mid-mounted transmission system and a bicycle. The housing of the mid-mounted transmission system is provided with a rotatable first power shaft and a transmission shaft; the sun gear is rotatably arranged on the first power shaft; a plurality of first planetary gears are fixedly connected with a multi-stage driving wheel group to form a first amplifying wheel group; a first clutch transmission assembly is arranged between the first power shaft and the sun gear, and a second clutch transmission assembly is arranged between the first power shaft and the first amplifying wheel group; the multi-stage driven wheel group is rotatably arranged on the transmission shaft, and a third clutch transmission assembly is arranged between the transmission shaft and each stage of the multi-stage driven wheel group; the shift convex portion of the first shift mechanism respectively abuts against the first clutch transmission assembly or the second clutch transmission assembly so that the first power shaft is respectively connected to the sun gear or the first amplifying wheel group; the shift convex portion of the second shift mechanism abuts against any third clutch transmission assembly so that the corresponding driven wheel is connected to the transmission shaft.

Description

Technical Field

[0001] The invention relates to the technical field of a mid-mounted speed change system for a bicycle, and in particular to a mid-mounted speed change system. Background Art

[0002] The transmission types of bicycles are generally divided into derailleur transmissions, hub transmissions, and mid-mounted internal transmissions. Derailleur transmissions are all external, particularly easy to damage, easy to drop chains, and difficult to maintain. Although hub transmissions are maintenance-free, they are very complicated and heavy in weight due to the fact that the transmission mechanism is very complex, and the weight is distributed on the rear wheel, so it is also particularly difficult to change tires. The riding experience is not good and it is not widely used. The mid-mounted transmission is set in the middle of the car, which is most in line with the distribution of the center of gravity. However, there are very few mid-mounted transmissions on the market. The existing gearboxes for mid-mounted transmissions are simply gears arranged side by side. Therefore, the more speed levels and the more gears there are, the heavier the weight. In order to promote the iterative progress of bicycle technology, there is an urgent need for a mid-mounted transmission box with a compact structure, a wide speed range, light weight, and a simple speed structure. Summary of the invention

[0003] In view of this, the present invention provides a mid-speed transmission system to solve the technical problems in the above-mentioned background technology.

[0004] To achieve one or part or all of the above purposes or other purposes, the present invention provides: a mid-mounted transmission system, comprising: a housing, a first power shaft that is at least partially hollow, a first shift mechanism, a transmission shaft that is at least partially hollow, a second shift mechanism, a first planetary gear set, a multi-stage driving wheel set, and a multi-stage driven wheel set;

[0005] The first power shaft and the transmission shaft can both be rotatably connected to the housing, and the first power shaft has a first power input end with both ends extending out of the housing, and the transmission shaft has a first power output end with one end extending out of the housing;

[0006] The inner gear ring of the first planetary gear set is fixed on the housing, and the sun gear is rotatably arranged on the first power shaft; a plurality of first planetary gears are fixedly connected to the multi-stage driving gear set to form a first amplifying gear set;

[0007] The multi-stage driving wheel set is rotatably arranged on the first power shaft;

[0008] A first clutch transmission assembly is provided between the first power shaft and the sun gear, and a second clutch transmission assembly is provided between the first power shaft and the first amplifying wheel set;

[0009] The multi-stage driven wheel set is rotatably arranged on the transmission shaft, and a third clutch transmission assembly is arranged between the transmission shaft and each stage of the multi-stage driven wheel set;

[0010] The first shift mechanism has a movable first limit shaft extending into the first power shaft, and the second shift mechanism has a movable second limit shaft extending into the transmission shaft; both the first limit shaft and the second limit shaft have a shift convex portion;

[0011] The first shifting mechanism can drive the first limiting shaft so that its shifting protrusion abuts against the first clutch transmission assembly to achieve a transmission connection between the first power shaft and the sun gear, or drive the first limiting shaft so that its shifting protrusion abuts against the second clutch transmission assembly to achieve a transmission connection between the first power shaft and the first amplifying wheel group; the second shifting mechanism can drive the second limiting shaft so that its shifting protrusion abuts against any of the third clutch transmission assemblies to achieve a transmission connection between the corresponding driven wheel and the transmission shaft.

[0012] Preferably, the multi-stage driving wheel set includes a second planetary gear set, a second driving wheel, a third driving wheel and an axial connection structure; the multi-stage driven wheel set includes: a first driven wheel, a second driven wheel and a third driven wheel;

[0013] The second planetary gear set includes a planet carrier, a plurality of second planetary gears and a first driving wheel; the first driving wheel is provided with a connecting portion in the axial direction, and an inner tooth portion is provided on the inner wall of the first driving wheel; the planet carrier is rotatably arranged on the first power shaft, and the plurality of second planetary gears mesh with the inner tooth portion of the first driving wheel to form a second amplifying wheel set;

[0014] A fourth clutch transmission assembly is provided between the first power shaft and the planet carrier; the first shift mechanism can drive the first limit shaft to make its shift convex portion abut against the fourth clutch transmission assembly so that the first power shaft and the planet carrier are in transmission connection;

[0015] The second driving wheel is mounted on the connecting portion and is coaxially fixed to the first driving wheel;

[0016] The third driving wheel, the first driving wheel and the plurality of second planetary wheels are connected via an axial connection structure; the third driving wheel is connected to the first power shaft via a first clutch assembly;

[0017] The first driving wheel is meshed with the first driven wheel, the second driving wheel is meshed with the second driven wheel, and the third driving wheel is meshed with the third driven wheel.

[0018] Preferably, mounting holes are provided on the first power shaft and the transmission shaft; the first clutch transmission assembly, the second clutch transmission assembly and the fourth clutch transmission assembly are all composed of a first pawl and a second ratchet structure, the first pawl is connected with a spring sheet, and the first pawl is assembled into the mounting hole through the spring sheet, the first ratchet structure is arranged on the sun gear of the first planetary gear set, the third driving gear and the planetary carrier of the second planetary gear set, the first pawl is compressed by the spring sheet and is in a contracted state when not abutted by the shifting protrusion, and is not connected to the corresponding first ratchet structure; the first pawl is in an extended state when abutted by the shifting protrusion, and can be transmission-connected to the corresponding first ratchet structure, and a avoidance space is formed between the first pawl and the mounting hole;

[0019] The third clutch transmission assembly is composed of a second pawl and a second ratchet structure, the second pawl is connected to a spring sheet, and the second pawl is assembled into the mounting hole through the spring sheet, the second ratchet structure is arranged on each level of the multi-stage slave wheel group, the second pawl is compressed by the spring sheet and is in a contracted state when not abutted by the shift protrusion, and is not connected to the corresponding second ratchet structure; the second pawl is in an extended state when abutted by the shift protrusion, and can be transmission-connected to the corresponding second ratchet structure, and there is no avoidance space between the outer wall of the second pawl and the inner wall of the mounting hole.

[0020] Preferably, the first shift mechanism and the second shift mechanism both include a control module and a control motor;

[0021] Axially extending threaded holes are provided inside the first power shaft and the transmission shaft;

[0022] The outer walls of the first limiting shaft and the second limiting shaft are both provided with external threads threadedly connected to the threaded hole;

[0023] The first limiting shaft and the second limiting shaft are both provided with axially penetrating connection holes, the connection holes are connected to the rotating shaft of the control motor, and the screw can move along the axial direction of the rotating shaft of the control motor;

[0024] The control module is electrically connected to the control motor.

[0025] Preferably, the first pawl and the second pawl are both provided with grooves connected to the spring sheet, and the first pawl and the second pawl are provided with transition inclined walls, which can abut against the transition inclined walls when the shift protrusion moves axially.

[0026] Preferably, the connecting portion is an axial protrusion connected to the first driving wheel, and the outer wall of the axial protrusion is provided with splines.

[0027] Preferably, the second planetary gear set further comprises a cylindrical gear;

[0028] When the plurality of second planetary gears of the second planetary gear set are assembled on the planet carrier, the ratchet structure of the second planetary gear and the planet carrier are staggered in the axial direction;

[0029] The spur gear is fixedly arranged on the housing, and the spur gear is meshed with a plurality of second planetary gears of the second planetary gear set.

[0030] Preferably, the housing comprises a left cover, a right cover and a middle housing with openings at both ends;

[0031] One end of the first power shaft passes through the left cover and is connected to the left cover through a bearing, and the other end passes through the right cover and is connected to the right cover through a bearing;

[0032] One end of the transmission shaft is connected to the left cover through a bearing, and the other end passes through the right cover and is connected to the right cover through a bearing;

[0033] The left cover is sealedly connected to an opening at one end of the middle shell, and the right cover is sealedly connected to an opening at the other end of the middle shell.

[0034] Preferably, it further comprises a first reversing gear set, wherein the first reversing gear set comprises a plurality of reversing planetary gears, a transmission frame and an output cylinder;

[0035] The transmission frame is provided with an axially displaced internal gear ring and a connecting ring, and the transmission frame is fixed to the transmission shaft through the connecting ring;

[0036] A plurality of reversing planetary gears are mounted on the housing, and the reversing planetary gears are meshed with the inner gear ring;

[0037] The output cylinder is rotatably mounted on the transmission shaft, and one end of the output cylinder is provided with an external tooth portion for meshing with the reversing planetary gear, and the other end of the output cylinder passes through the housing and is provided with a second power output end.

[0038] A mid-mounted transmission system comprises: a housing, a first power shaft which is at least partially hollow, a first shift mechanism, a transmission shaft which is at least partially hollow, a second shift mechanism, a first planetary gear set, a multi-stage driving wheel set, a multi-stage driven wheel set, and a second reversing gear set;

[0039] The first power shaft and the transmission shaft can both be rotatably connected to the housing, and the first power shaft has a first power input end with both ends extending out of the housing;

[0040] The second reversing gear set includes a transmission gear and an output gear, wherein the transmission gear is coaxially fixed on the transmission shaft, and the output gear is rotatably mounted on the first power shaft and meshes with the transmission gear; the output gear is provided with an axially extending power output end, and the power output end is arranged outside the housing;

[0041] The inner gear ring of the first planetary gear set is fixed on the housing, and the sun gear is rotatably arranged on the first power shaft; a plurality of first planetary gears are fixedly connected to the multi-stage driving gear set to form a first amplifying gear set;

[0042] The multi-stage driving wheel set is rotatably arranged on the first power shaft;

[0043] A first clutch transmission assembly is provided between the first power shaft and the sun gear, and a second clutch transmission assembly is provided between the first power shaft and the first amplifying wheel set;

[0044] The multi-stage driven wheel set is rotatably arranged on the transmission shaft, and a third clutch transmission assembly is arranged between the transmission shaft and each stage of the multi-stage driven wheel set;

[0045] The first shift mechanism has a movable first limit shaft extending into the first power shaft, and the second shift mechanism has a movable second limit shaft extending into the transmission shaft; both the first limit shaft and the second limit shaft have a shift convex portion;

[0046] The first shifting mechanism can drive the first limiting shaft so that its shifting protrusion abuts against the first clutch transmission assembly to achieve a transmission connection between the first power shaft and the sun gear, or drive the first limiting shaft so that its shifting protrusion abuts against the second clutch transmission assembly to achieve a transmission connection between the first power shaft and the first amplifying wheel group; the second shifting mechanism can drive the second limiting shaft so that its shifting protrusion abuts against any of the third clutch transmission assemblies to achieve a transmission connection between the corresponding driven wheel and the transmission shaft.

[0047] A mid-mounted transmission system comprises: a housing, a support shaft that is at least partially hollow, a first shift mechanism, a transmission shaft that is at least partially hollow, a second shift mechanism, a first planetary gear set, a multi-stage driving wheel set, a multi-stage driven wheel set, and a second power shaft;

[0048] The second power shaft, the support shaft and the transmission shaft can all be rotatably connected to the housing, and the second power shaft has a second power input end with both ends extending out of the housing, and the transmission shaft has a power output end with one end extending out of the housing; the second power shaft has a coaxially assembled input gear;

[0049] The inner gear ring of the first planetary gear set is fixed on the housing, and the sun gear is rotatably arranged on the support shaft; a plurality of first planetary gears are fixedly connected to the multi-stage driving gear set to form a first amplifying gear set;

[0050] The multi-stage driving wheel set is rotatably arranged on the support shaft; any stage of the multi-stage driving wheel set can be meshed with the input gear;

[0051] A first clutch transmission assembly is provided between the support shaft and the sun gear, and a second clutch transmission assembly is provided between the support shaft and the first amplifying wheel set;

[0052] The multi-stage driven wheel set is rotatably arranged on the transmission shaft, and a third clutch transmission assembly is arranged between the transmission shaft and each stage of the multi-stage driven wheel set;

[0053] The first shift mechanism has a movable first limit shaft extending into the interior of the support shaft, and the second shift mechanism has a movable second limit shaft extending into the interior of the transmission shaft; both the first limit shaft and the second limit shaft have a shift convex portion;

[0054] The first shifting mechanism can drive the first limiting shaft so that its shifting protrusion abuts against the first clutch transmission component to achieve a transmission connection between the support shaft and the sun gear, or drive the first limiting shaft so that its shifting protrusion abuts against the second clutch transmission component to achieve a transmission connection between the support shaft and the first amplifying wheel group; the second shifting mechanism can drive the second limiting shaft so that its shifting protrusion abuts against any of the third clutch transmission components to achieve a transmission connection between the corresponding driven wheel and the transmission shaft.

[0055] A bicycle comprises the above-mentioned mid-mounted speed change system.

[0056] Implementing the embodiments of the present invention will have the following beneficial effects:

[0057] After adopting the above scheme, since the core transmission components of the mid-mounted transmission system only include the first planetary gear set, the multi-stage driving wheel set and the multi-stage driven wheel set; the transmission process is adjusted by the first limiting shaft arranged inside the first power shaft and the second limiting shaft arranged inside the transmission shaft, the multi-stage driving wheel set and the multi-stage driven wheel set are directly transmitted, and no additional space is required to arrange the transmission gear set and the speed change gear set, which optimizes the transmission process, simplifies the gearbox structure of the bicycle, and can make the weight and volume smaller. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0059] in:

[0060] Figure 1 It is a schematic diagram of the overall structure of the first embodiment;

[0061] Figure 2It is an exploded view of the overall structure of the first embodiment;

[0062] Figure 3 It is a cross-sectional view of the overall structure of the first embodiment;

[0063] Figure 4 for Figure 3 AA section view in;

[0064] Figure 5 for Figure 3 BB section view in;

[0065] Figure 6 for Figure 3 CC section view in;

[0066] Figure 7 for Figure 3 DD section view in;

[0067] Figure 8 This is a schematic diagram of the structure without a housing of the first embodiment;

[0068] Fig. 9 This is a schematic diagram of the separation of the first power shaft structure of the first embodiment;

[0069] Fig.10 It is a schematic diagram of the separation of the transmission shaft structure of the first embodiment;

[0070] Fig.11 An exploded view of the second planetary gear set of the first embodiment;

[0071] Fig.12 is a schematic structural diagram of the first planetary gear set in Embodiment 1;

[0072] Fig.13 It is a structural schematic diagram of the first shift mechanism of Embodiment 1;

[0073] Fig.14 Schematic diagram of the first pawl and the first power shaft, and the second pawl and the transmission shaft in the first embodiment;

[0074] Fig.15 is a cross-sectional view of the first pawl and the second pawl when assembled in the first embodiment;

[0075] Fig.16 It is a schematic structural diagram of the second pawl and the spring piece of the first embodiment;

[0076] Fig.17 The structure of the first reversing gear set in the second embodiment is shown in FIG. Figure 1 ;

[0077] Fig.18 The structure diagram of the first reversing gear set of the second embodiment Figure 2 ;

[0078] Fig.19 It is a schematic diagram of the structure of the embodiment 3 equipped with a second reversing gear set;

[0079] Fig. 20 It is a schematic diagram of the internal structure of the embodiment 3 equipped with a second reversing gear set;

[0080] Fig.21 This is a structural separation diagram of the third embodiment equipped with a second reversing gear set;

[0081] Fig. 22 Schematic diagram of the internal structure of the fourth embodiment.

[0082] Reference numerals:

[0083] 1. Shell; 101. Right cover; 102. Left cover; 103. Middle shell;

[0084] 2. First power shaft; 200. Mounting hole; 201. First power input end; 202. Threaded hole; 21. Support shaft; 22. Second power shaft; 220. Input gear; 221. Second power input end;

[0085] 3. First shift mechanism; 301. First limit shaft; 301a. Shift convex portion; 301b. Connecting hole; 302. Control module; 302a. Control board; 302b. Battery; 302c. Protective shell; 303. Control motor;

[0086] 4, transmission shaft; 401, first power output end; 402, transmission spline; 41, first reversing gear set; 410, reversing planetary gear; 411, transmission frame; 411a, inner gear ring; 411b, connecting ring; 412, output cylinder; 412a, outer gear portion; 412b, second power output end; 42, second reversing gear set; 420, output gear; 420a, third power output end; 421, transmission gear;

[0087] 5. Second shift mechanism; 501. Second limit shaft;

[0088] 6. First planetary gear set; 601. Sun gear; 602. Internal ring gear; 603. First planetary gear;

[0089] 7. Multi-stage driving wheel set; 70. Second planetary gear set; 702. Planet carrier; 703. Second planetary gear; 704. Cylindrical gear; 71. First driving wheel; 710. Connecting portion; 711. Internal gear portion; 712. Connecting ear; 72. Second driving wheel; 73. Third driving wheel; 74. Axial connection structure; 740. Limit rod; 741. Limit ring; 742. Snap ring;

[0090] 8. Multi-stage driven wheel set; 801. first driven wheel; 802. second driven wheel; 803. third driven wheel;

[0091] 90. First pawl; 91. First ratchet structure; 92. Second pawl; 920. Groove; 921. Transition inclined wall; 93. Second ratchet structure; 94. Shrapnel. DETAILED DESCRIPTION

[0092] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by technicians in the technical field of the present invention; the terms used in the specification of the application herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention; the terms "including" and "having" and any variations thereof in the specification and claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first", "second", etc. in the specification and claims of the present invention or the above-mentioned drawings are used to distinguish different objects, not to describe a specific order.

[0093] Reference to an "embodiment" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiment may be included in at least one embodiment of the present invention. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0094] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings.

[0095] Embodiment 1:

[0096] As attached Figure 1-16 As shown, an embodiment of the present invention provides a mid-mounted transmission system, which includes: a housing 1, a first power shaft 2 that is at least partially hollow, a first shift mechanism 3, a transmission shaft 4 that is at least partially hollow, a second shift mechanism 5, a first planetary gear set 6, a multi-stage driving wheel set 7, and a multi-stage driven wheel set 8;

[0097] The first power shaft 2 and the transmission shaft 4 can both be rotatably connected to the housing 1, and the first power shaft 2 has a first power input end 201 with both ends extending out of the housing 1, and the transmission shaft 4 has a first power output end 401 with one end extending out of the housing 1;

[0098] The inner gear ring 602 of the first planetary gear set 6 is fixed on the housing 1, and the sun gear 601 is rotatably arranged on the first power shaft 2; a plurality of first planetary gears 603 are fixedly connected to the multi-stage driving gear set 7 to form a first amplifying gear set;

[0099] The multi-stage driving wheel set 7 is rotatably arranged on the first power shaft 2;

[0100] A first clutch transmission assembly is provided between the first power shaft 2 and the sun gear 601, and a second clutch transmission assembly is provided between the first power shaft 2 and the first amplifying wheel set;

[0101] The multi-stage driven wheel set 8 is rotatably arranged on the transmission shaft 4, and a third clutch transmission assembly is arranged between the transmission shaft 4 and each stage of the multi-stage driven wheel set 8;

[0102] The first shift mechanism 3 has a movable first limit shaft 301 extending into the first power shaft 2, and the second shift mechanism 5 has a movable second limit shaft 501 extending into the transmission shaft 4; both the first limit shaft 301 and the second limit shaft 501 have a shift convex portion 301a;

[0103] The first shifting mechanism 3 can drive the first limiting shaft 301 so that its shifting protrusion 301a abuts against the first clutch transmission component to achieve a transmission connection between the first power shaft 2 and the sun gear 601, or drive the first limiting shaft 301 so that its shifting protrusion 301a abuts against the second clutch transmission component to achieve a transmission connection between the first power shaft 2 and the first amplifying wheel group; the second shifting mechanism 5 can drive the second limiting shaft 501 so that its shifting protrusion 301a abuts against any third clutch transmission component to achieve a transmission connection between its corresponding driven wheel and the transmission shaft 4.

[0104] In this embodiment, the first power shaft 2 has a first power input end 201 with both ends extending out of the housing 1. The two first power input ends 201 are used to connect the bicycle crank and pedals, and the transmission shaft 4 has a first power output end 401 extending out of the housing 1 at one end. The first power output end 401 is used to connect the bicycle chainring, and the chainring is then transmitted to the wheel through a chain or the like. The multi-stage driving wheel set 7 and the multi-stage driven wheel set 8 can be a combination of multiple gears of different sizes or specifications. For example, the multi-stage driving wheel set 7 is a combination of three gears of different sizes, and the multi-stage driven wheel set 8 is a combination of three gears of different sizes, each gear corresponding to a stage, such as Figure 6 and Figure 7As shown, of course, it can also be a combination of four, five or six gears, or even more, or a combination of two gears, as long as these gears are guaranteed to be meshed with each stage of the driving gear and each stage of the driven gear after installation; more specifically, the multiple first planetary gears 603 of the above-mentioned first planetary gear set 6 are fixedly connected with the multi-stage driving wheel set 7 to form a first amplifying wheel set, which means that its sun gear 601 is coaxially arranged on the first power shaft 2 with the multi-stage driving wheel set 7, and the multiple first planetary gears 603 between the sun gear 601 and the inner ring 602 are fixedly connected with the multi-stage driving wheel set 7, and the formed amplifying wheel set is a whole. When in use, the sun gear 601 drives the multiple first planetary gears 603 to rotate, and then drives the multi-stage driving wheel set 7 to rotate together, that is, the power is transmitted through the first power input end 201 of the first power shaft 2, and after being amplified by the multiple first planetary gears 603, it drives the multi-stage driving wheel set 7 to rotate. At this time, the multi-stage driving wheel set 7 provides the first input speed for the multi-stage driven wheel set 8. In contrast, the multi-stage driving wheel set 7 can be directly connected to the first power shaft 2 through the second clutch transmission assembly. At this time, the angular velocity of the first power shaft 2 is consistent with the angular velocity of the multi-stage driving wheel set 7, that is, the multi-stage driving wheel set 7 provides a second input speed for the multi-stage driven wheel set 8, and the second input speed is different from the first input speed.

[0105] The multi-stage driven wheel set 8 is rotatably arranged on the transmission shaft 4. Relatively, each gear on the multi-stage driven wheel set 8 is independent of each other when rotating. The first clutch transmission assembly, the second clutch transmission assembly and the third clutch transmission assembly are all components that can separate or engage the transmission, and can be a ratchet 90 structure as described later, or can be other forms, for example, in the form of two friction plates, and the abutment or separation of the two friction plates is controlled by the shift convex portion 301a to control the separation or engagement of the transmission.

[0106] See attached Figure 3 - Figure 8When working, if the first shifting mechanism 3 drives the first limiting shaft 301 to make its shifting protrusion 301a abut against the first clutch transmission component so that the first power shaft 2 is connected to the sun gear 601 of the first planetary gear set 6, at this time, the first amplifying wheel set is not connected to the first power shaft 2, and the power is transmitted through the first power input end 201 of the first power shaft 2, and after being amplified by the multiple first planetary gears 603 of the first planetary gear set 6, the multi-stage driving wheel set 7 is driven to rotate, and the second shifting mechanism 5 drives the second limiting shaft 501 to make its shifting protrusion 301a abut against the third clutch transmission component to be output, so that the corresponding driven wheel is connected to the transmission shaft 4. For example, the shifting protrusion 301a of the second limiting shaft 501 abuts against the first gear on the left of the multi-stage driven wheel set 8. At this time, the power is transmitted from the first gear on the left of the multi-stage driving wheel set 7 to the first gear on the left of the multi-stage driven wheel set 8, and then to the transmission shaft 4, and finally drives the sprocket connected to the first power output end 401 to output. Although the multi-stage driving wheel set 7 and the multi-stage driven wheel set 8 are all meshed in the above transmission process, since only the first gear on the left of the multi-stage driven wheel set 8 has a transmission relationship with the transmission shaft 4, the other gears on the multi-stage driven wheel set 8 are idle and do not affect the transmission process. When the first gear shifting mechanism 3 drives the first limiting shaft 301 to make its shifting protrusion 301a abut against the second clutch transmission assembly, the first power shaft 2 and the first amplifying wheel group are connected in transmission; at this time, the sun gear 601 of the first planetary gear set 6 is not connected to the first power shaft 2, and the power is transmitted through the first power input end 201 of the first power shaft 2, directly driving the multi-stage driving wheel group 7 to rotate, and the second gear shifting mechanism 5 drives the second limiting shaft 501 to make its shifting protrusion 301a abut against the third clutch transmission assembly required to be output, so that the corresponding driven wheel is connected in transmission to the transmission shaft 4. Taking the shifting protrusion 301a of the second limiting shaft 501 abutting against the first gear on the left of the multi-stage driven wheel group 8 as an example, at this time, the power is transmitted from the first gear on the left of the multi-stage driving wheel group 7 to the first gear on the left of the multi-stage driven wheel group 8, and then to the transmission shaft 4, which finally drives the output of the sprocket connected to the first power output end 401 of the transmission shaft 4. In the above transmission process, although all levels of the multi-stage driving wheel set 7 and the multi-stage driven wheel set 8 are meshed, since only the first gear on the left of the multi-stage driven wheel set 8 has a transmission relationship with the transmission shaft 4, the other gears on the multi-stage driven wheel set 8 are idling. Similarly, there is no transmission relationship between the sun gear 601 of the first planetary gear set 6 and the first power shaft 2, and the sun gear 601 is also idling, which does not affect the transmission process.

[0107] In summary, when both the multi-stage driving wheel set 7 and the multi-stage driven wheel set 8 are three-stage, the first power shaft 2 is connected to the sun gear 601 or the first amplifying wheel set, so that the multi-stage driving wheel set 7 provides two different input speeds for the multi-stage driven wheel set 8, and the transmission shaft 4 is connected to each stage of the three-stage driven wheel set to obtain a different output speed. The whole system can provide 2×3=6 different speed changes. Similarly, when both the multi-stage driving wheel set 7 and the multi-stage driven wheel set 8 are four-stage, 2×4=8 different speed changes can be provided. The same is true for other stages, which will not be repeated.

[0108] See attached Fig. 9 and Fig.11 The multi-stage driving wheel set 7 includes a second planetary gear set 70, a second driving wheel 72, a third driving wheel 73 and an axial connection structure 74; the multi-stage driven wheel set 8 includes: a first driven wheel 801, a second driven wheel 802 and a third driven wheel 803;

[0109] The second planetary gear set 70 includes a planet carrier 702, a plurality of second planetary gears 703 and a first driving wheel 71; a connecting portion 710 is provided in the axial direction of the first driving wheel 71, and an inner tooth portion 711 is provided on the inner wall of the first driving wheel 71; the planet carrier 702 is rotatably disposed on the first power shaft 2, and the plurality of second planetary gears 703 of the second planetary gear set 70 are meshed with the inner tooth portion 711 of the first driving wheel 71 to form a second amplifying wheel set;

[0110] A fourth clutch transmission assembly is provided between the first power shaft 2 and the planet carrier 702; the first shift mechanism 3 can drive the first limit shaft 301 to make its shift convex portion 301a abut against the fourth clutch transmission assembly so that the first power shaft 2 and the planet carrier 702 are in transmission connection;

[0111] The second driving wheel 72 is mounted on the connecting portion 710 and is coaxially fixed to the first driving wheel 71;

[0112] The third driving wheel 73, the first driving wheel 71 and the plurality of second planetary wheels 703 of the first planetary gear set 6 are connected via an axial connection structure 74; the third driving wheel 73 is connected to the first power shaft 2 via a first clutch assembly;

[0113] The first driving wheel 71 meshes with the first driven wheel 801 , the second driving wheel 72 meshes with the second driven wheel 802 , and the third driving wheel 73 meshes with the third driven wheel 803 .

[0114] Specifically, a connecting portion 710 is provided in the axial direction of the first driving wheel 71. The connecting portion 710 can be specifically an axial protrusion on the first driving wheel 71, and a spline is provided on the outer wall of the axial protrusion. The second driving wheel 72 is sleeved on the connecting portion 710 and rotates with the first driving wheel 71, and has the same angular velocity as the first driving wheel 71; and the third driving wheel 73 is fixedly connected to the plurality of first planetary gears 603 and the first driving wheel 71 of the first planetary gear set 6 through the axial connecting structure 74, so that the third driving wheel 73 has the same angular velocity as the first driving wheel 71, and ensures that the first planetary gear set 6 can drive the third driving wheel 73 to rotate. In this embodiment, the first amplifying wheel set has The first planetary gear set 6 is an enlarged wheel set formed by connecting a plurality of first planetary gears 603 of the first planetary gear set 6 and a third driving wheel 73; accordingly, the second clutch transmission assembly is used to connect the third driving wheel 73 and the first power shaft 2; and in order to provide the mid-mounted transmission system with more speed adjustment options on the basis of the three-stage driving wheel, a planet carrier 702 and a plurality of second planetary gears 703 are further provided inside the first driving wheel 71, wherein the planet carrier 702 is rotatably arranged on the first power shaft 2, and establishes a transmission relationship with the first power shaft 2 through the fourth clutch transmission assembly, and the planet carrier 702 has a plurality of extension arms for mounting a plurality of second planetary gears 703, and the plurality of second planetary gears 703 are connected to the first driving wheel 71 The inner tooth portion 711 of the first limit shaft 301 is meshed to form a second amplified wheel set. When the shift protrusion 301a of the first limit shaft 301 moves to the fourth clutch transmission assembly position, the fourth clutch transmission assembly connects the planetary carrier 702 and the first power shaft 2. At this time, power is transmitted through the first power input end 201 of the first power shaft 2, and is amplified by the planetary carrier 702 and the multiple second planetary gears 703 and then transmitted to the first driving wheel 71, that is, the multi-stage driving wheel set 7 can provide a third input speed for the multi-stage driven wheel set 8. It should also be noted that the system can be provided with a third input speed by setting the size relationship between the radius R1 of the revolution circle of the multiple first planetary gears 603 and the radius R2 of the revolution circle of the multiple second planetary gears 703. Different speed shifting options can be provided, which can be specifically set according to actual speed shifting requirements. For example, when the radius R1 of the orbital circle of the multiple first planetary gears 603 of the first planetary gear set 6 is smaller than the radius R2 of the orbital circle of the multiple second planetary gears 703 of the second planetary gear set 70, the first input speed of the first amplifying wheel set and the second input speed of the second amplifying wheel set are different. In summary, when the multi-stage driving wheel set 7 and the multi-stage driven wheel set 8 of the mid-speed transmission system are both three-stage, since the second planetary gear set 70 is provided in the multi-stage driving wheel set 7, the entire system can provide 3×3=9 sets of different speed shifting, that is, the mid-speed transmission system provides more speed adjustment options in a limited space.

[0115] In order to further improve the compactness and stability of the structure inside the multi-stage driving gear set 7, the second planetary gear set 70 also includes a cylindrical gear 704; when the plurality of second planetary gears 703 of the second planetary gear set 70 are assembled on the planet carrier 702, the positions where the second planetary gears 703 are connected to the planet carrier 702 and the fourth clutch transmission assembly are staggered in the axial direction; the cylindrical gear 704 is fixedly arranged on the housing 1, and the cylindrical gear 704 is meshed with the plurality of second planetary gears 703; specifically, the extension arm of the planet carrier 702 is a structure that extends outwardly in an axially inclined manner, such as Figure 6 As shown, the part of the planetary carrier 702 connected to the fourth clutch transmission assembly and the second driving wheel 72 are on the same vertical plane, and the outer tooth part of the plurality of second planetary gears 703 and the first driving wheel 71 for meshing with the multi-stage driven wheel set 8 are on the same vertical plane. By making full use of the internal space of the first driving wheel 71, while increasing the speed output of the mid-mounted transmission system, it can also ensure that its space and volume do not increase; and the distance between the fourth clutch transmission assembly and the second clutch transmission assembly is reduced, thereby reducing the moving distance of the first limit shaft 301, and further optimizing the structural layout inside the first power shaft 2.

[0116] See attached Figure 5 , Figure 6 , Fig.12 , Fig.14 , Fig.15 and Fig.16 The first clutch transmission assembly, the second clutch transmission assembly and the fourth clutch transmission assembly are all composed of a first pawl 90 and a first ratchet structure 91. The first pawl 90 is connected with a spring sheet 94. The first pawl 90 is assembled into the mounting hole 200 through the spring sheet 94. The first ratchet structure 91 is arranged on the sun gear 601 of the first planetary gear set 6, the third driving gear 73 and the planet carrier 702 of the second planetary gear set 70. When the first pawl 90 is not abutted by the shift protrusion 301a, it is compressed by the spring sheet and is in a contracted state, and is not connected to the corresponding first ratchet structure 91; when the first pawl 90 is abutted by the shift protrusion 301a, it is in an extended state, and can be transmission-connected to the corresponding first ratchet structure 91, and a avoidance space is formed between the first pawl 90 and the mounting hole 200.

[0117] The third clutch transmission assembly is composed of a second pawl 92 and a second ratchet structure 93. The second pawl 92 is connected to a spring sheet 94, and the second pawl 92 is assembled into the mounting hole 200 through the spring sheet 94. The second ratchet structure 93 is arranged on each level of the multi-level slave wheel group 8. When the second pawl 92 is not abutted by the shift protrusion 301a, it is compressed by the spring sheet 94 and is in a contracted state, and is not connected to the corresponding second ratchet structure 93; when the second pawl 92 is abutted by the shift protrusion 301a, it is in an extended state, and can be transmission-connected to the corresponding second ratchet structure 93, and there is no avoidance space between the outer wall of the second pawl 92 and the inner wall of the mounting hole 200.

[0118] Specifically, the first clutch transmission assembly, the second clutch transmission assembly and the fourth clutch transmission assembly are distributed along the axial direction of the first power shaft 2 with the same spacing, which can not only achieve the compactness of the structural distribution, but also enable the first shift mechanism 3 to use simpler instructions to control the movement of the first limit shaft 301, that is, it is only necessary to control the first limit shaft 301 to move the same distance each time to achieve switching between different clutch transmission assemblies. Similarly, the third clutch transmission assembly is provided with three corresponding to the three-stage driven wheels of the multi-stage driven wheel group 8, and the three third clutch transmission assemblies are distributed along the axial direction of the transmission shaft 4 with the same spacing, which will not be repeated here. In this embodiment, taking the first clutch transmission assembly on the first power shaft 2 as an example, a plurality of mounting holes 200 are provided at positions on the first power shaft 2 corresponding to the third driving wheel 73, a plurality of first pawls 90 are correspondingly installed on the mounting holes 200, and one end of a spring sheet 94 is connected to the first pawl 90, and the other end of the spring sheet 94 is fixed to the inner wall of the mounting hole 200. When the first pawl 90 is not abutted by the shifting protrusion 301a, it is compressed by the spring sheet 94 and is in a contracted state; when the first pawl 90 is abutted by the shifting protrusion 301a, it is in an extended state; the inner ring of the third driving wheel 73 is provided with a first ratchet structure 91, and when the first power shaft 2 is moved along the gear shifting protrusion 301a, the first pawl 90 is in an extended state. Fig.15 When the first pawl 90 rotates forward in the direction of the arrow shown in the figure, the first pawl 90 is abutted by the shifting protrusion 301a, so that it establishes a transmission connection with the first ratchet structure 91 on the third driving wheel 73, thereby driving the third driving wheel 73 to rotate together. Fig.15When the first power shaft 20 rotates in the opposite direction of the arrow shown, since there is an avoidance space between the first pawl 90 and the inner wall of the mounting hole 200, when the first power shaft 20 rotates in the reverse direction, the first pawl 90 is squeezed by the first ratchet structure 91 and retreats into the avoidance space, that is, the reverse rotation of the first power shaft 20 cannot drive the third driving wheel 73 to rotate together, so as to avoid affecting the normal use of other transmission structures on the first power shaft 2 and the transmission shaft 4 when the pedal is stepped on in the reverse direction. The principles of the second clutch assembly and the fourth clutch assembly are the same as those of the first clutch assembly and are not described here. The third clutch assembly is different from the above three clutch assemblies in that the second pawl 92 of the third clutch assembly is thicker than the first pawl 91. When the second pawl 92 is assembled to the mounting hole 200 on the transmission shaft 4, the second The gap between the pawl 92 and the mounting hole 200 is only enough for the second pawl 92 to move along the axial direction of the mounting hole 200, and it is impossible to produce radial swing, so that the multi-stage driven wheel group 8 can drive the transmission shaft 4 to rotate in either direction. On the contrary, when the bicycle is going downhill or gliding, the rotation of the transmission shaft 4 will also drive the multi-stage driven wheel group 8 to rotate, and then drive the rotation of the multi-stage driving wheel group 7. Since the multi-stage driving wheel group 7 is in reverse at this time, the first pawl 90 will be squeezed by the first ratchet structure 91 and retreat to the avoidance space, so that the first power shaft 2 will not rotate with the multi-stage driving wheel group 7, avoiding the idling of the pedal assembled on the first power shaft 2. In addition, since the second pawl 92 does not need to realize unidirectional rotation, the processing cost of the second pawl 92 is greatly reduced.

[0119] In order to enable the shift protrusion 301a to quickly convert the axially distributed first pawl 90 or the second pawl 92 to the extended state when it moves axially, a transition inclined wall 921 is provided on the first pawl 90 and the second pawl 92, and the shift protrusion 301a can easily convert the first pawl 90 or the second pawl 92 to the extended state by abutting against the transition inclined wall 921; and in order to facilitate the connection stability between the spring piece 94 and the first pawl 90 or the second pawl 92, and to ensure that the first pawl 90 or the second pawl 92 can be quickly reset by the spring piece 94 when it is not abutted by the shift protrusion 301a, a groove 920 is provided on the top of the first pawl 90 and the second pawl 92, one end of the spring piece 94 is embedded in the groove 921, and the other end of the spring piece 94 is fixed to the inner wall of the mounting hole 200.

[0120] See attached Figure 6 and Fig.13 , the first shift mechanism 3 and the second shift mechanism 5 both include a control module 302 and a control motor 303;

[0121] The first power shaft 2 and the transmission shaft 4 are provided with axially extending threaded holes 202 inside;

[0122] The outer walls of the first limiting shaft 301 and the second limiting shaft 501 are both provided with external threads threadedly connected to the threaded hole 202;

[0123] The first limiting shaft 301 and the second limiting shaft 501 are both provided with an axially penetrating connection hole 301b, the connection hole 301b is connected to the rotating shaft of the control motor 303, and the screw can move along the axial direction of the rotating shaft of the control motor 303;

[0124] The control module 302 is electrically connected to the control motor 303 .

[0125] Since the first gear shift mechanism 3 and the second gear shift mechanism 5 adopt the same structure, this embodiment is only described with reference to the first gear shift mechanism 3. In order to prevent relative rotation between the first limit shaft 301 and the rotating shaft of the control motor 303, in this embodiment, the cross-section of the connecting hole 301b and the cross-section of the rotating shaft of the control motor 303 are both hexagonal. When the control motor 303 is started to rotate its rotating shaft, the connecting hole 301b and the rotating shaft of the control motor 303 cannot rotate relative to each other, and the first limit shaft 301 is threadedly connected to the threaded hole 202 of the first power shaft 2, so that the first limit shaft 301 produces a displacement movement along the axial direction of the first power shaft 2. In other embodiments, the cross-sections of the connecting hole 301b and the rotating shaft of the control motor 303 can also be D-shaped, triangular or other special shapes. The control module 302 includes a battery 302b and a control board 302a, wherein the battery 302b and the control board 302a are arranged along the axial direction of the first power shaft 2, and the control board 302a is at the end position of the first power shaft 2, so that the wireless receiving element of the control board 302a is not hindered by the battery 302b and other elements, ensuring smooth communication between the control board 302a and the external electronic device. Specifically, three gear position instructions can be set in the control board 302a, and the three gear position instructions are transmitted to the control motor 303, so that the shaft of the control motor 303 rotates in a specified direction and number of revolutions. For example, the control board 302a sends a first gear position instruction to the control motor 303, so that the first limit shaft 301 moves, so that its shift convex portion 301a is placed in the position of the first clutch transmission component, and drives the first clutch transmission component to connect with the sun gear 601 of the first planetary gear set 6, so as to establish a transmission connection between the sun gear 601 of the first planetary gear set 6 and the first power shaft 2. Fig.13 As shown, in order to facilitate the assembly of the battery 302b and the control board 302a into the interior of the first power shaft 2, the control module 302 is also provided with a protective shell 302c, which wraps the battery 302b and the control board 302a, and an elastic latch cam is provided at the end of the protective shell 302c for connection with the first power shaft 2, so as to facilitate the disassembly and assembly of the control module 302 as a whole from the first power shaft 2.

[0126] In order to ensure the connection stability and compactness between the first planetary gear set 6 and the multi-stage driving gear set 7, the axial connection structure 74 of this embodiment includes a plurality of limiting rods 740, a plurality of retaining rings 742 and a limiting ring 741; the plurality of limiting rods 740 and the plurality of retaining rings 742 are arranged corresponding to the plurality of first planetary gears 603 of the first planetary gear set 6; the limiting ring 741 is placed on the side of the plurality of first planetary gears 603 away from the third driving gear 73, one end of the limiting rod 740 passes through the first driving gear 71, the third driving gear 73, the planetary gear and the limiting ring 741 in sequence, the retaining ring 742 is clamped on the end of the limiting rod 740 and is arranged in contact with the limiting ring 741. Specifically, the limiting ring 741 is provided with a plurality of through holes corresponding to the plurality of first planetary gears 603 of the first planetary gear set 6, and the connection of the first driving gear 71 A plurality of connecting ears 712 are correspondingly provided on the inner wall of the connecting portion 710, and a through hole is provided on the connecting ear 712, and the limiting rod 740 is a T-shaped rod structure, and the end of the limiting rod 740 with a smaller outer diameter is provided with a groove for the clamping ring 742 to be clamped. During assembly, the end of the limiting rod 740 with a smaller outer diameter is passed through the connecting ear 712 of the first driving wheel 71, the third driving wheel 73, the first planetary gear 603 and the corresponding positions of the limiting ring 741 in sequence, and finally the clamping ring 742 is clamped in the clamping groove of the limiting rod 740, that is, the first planetary gear 603, the third driving wheel 73 and the first driving wheel 71 are connected into one, and the second driving wheel 72 is limited by the third driving wheel 73 and cannot move axially, so that the multiple first planetary gears 603 can drive the multi-stage driving wheel group 7 to rotate together when they revolve.

[0127] In some embodiments, the housing 1 includes a left cover 102, a right cover 101, and a middle housing 103 with openings at both ends;

[0128] One end of the first power shaft 2 passes through the left cover 102 and is connected to the left cover 102 through a bearing, and the other end passes through the right cover 101 and is connected to the right cover 101 through a bearing;

[0129] One end of the transmission shaft 4 is connected to the left cover 102 through a bearing, and the other end passes through the right cover 101 and is connected to the right cover 101 through a bearing;

[0130] The left cover 102 is sealedly connected to one end opening of the middle shell 103 , and the right cover 101 is sealedly connected to the other end opening of the middle shell 103 .

[0131] In this embodiment, the transmission structure of the entire mid-speed transmission system of the above structure is sealed inside the housing 1, and the interfaces between the first power shaft 2 and the left cover 102 and the right cover 101 can be sealed using a sealing cover, and a sealing ring is arranged inside the sealing cover for further sealing. When in use, it can prevent objects such as mud, dust, etc. from entering the transmission system to pollute and even affect the use of the transmission structure, and at the same time, it can achieve the effect of no cleaning and maintenance. After the bicycle is installed with the mid-speed transmission system of the present invention, even if riding on a muddy road, there is no need to worry about the system being damaged by foreign objects entering, which is particularly suitable for mountain bikes.

[0132] Embodiment 2:

[0133] See attached Fig.17 and attached Fig.18 The mid-mounted transmission system also includes a first reversing gear set 41, which includes a plurality of reversing planetary gears 410, a transmission frame 411 and an output cylinder 412; the transmission frame 411 is provided with an axially displaced inner gear ring 411a and a connecting ring 411b, and the transmission frame 411 is fixed to the transmission shaft 4 through the connecting ring 411b; a plurality of reversing planetary gears 410 are mounted on the housing 1, and the reversing planetary gears 410 are meshed with the inner gear ring 411a; the output cylinder 412 is rotatably mounted on the transmission shaft 4, and one end of the output cylinder 412 is provided with an outer tooth portion 412a for meshing with the reversing planetary gears 410, and the other end of the output cylinder 412 passes through the housing 1 and is provided with a second power output end 412b.

[0134] Specifically, when the mid-speed transmission system is applied to a bicycle, the second power output end 412b of the output cylinder 412 can be used to install a crankset; the inner wall of the connecting ring 411b of the transmission frame 411 is provided with a spline structure, and the outer wall of the transmission shaft 4 is provided with a transmission spline 402 connected to the connecting ring 411b. Through the spline connection, the transmission shaft 4 can drive the transmission frame 411 to transmit together when it rotates. In addition, since a plurality of reversing planetary gears 410 are installed on the housing 1, and the output cylinder 412 is rotatably mounted on the transmission shaft 4, The power is input through the transmission frame 411, transmitted by multiple reversing planetary gears 410, and finally output through the output cylinder 412. This method makes the direction of the output cylinder 412 opposite to the direction of the transmission shaft 4. Since the transmission shaft 4 and the first power shaft 2 are transmitted by external gear meshing, after the transmission of the first reversing gear set 41, the direction of the output cylinder 412 is the same as the direction of the first power shaft 2, that is, in this embodiment, the direction of the chainring installed on the output cylinder 412 is the same as the direction of the first power shaft 2.

[0135] Embodiment three:

[0136] See attached Fig.19 -Attached Fig.21The mid-speed transmission system further includes a second reversing gear set 42, which includes a transmission gear 421 and an output gear 420. This embodiment only describes the differences from the above embodiments. In this embodiment, a third power output end 420a is provided on the output gear 420. Specifically, the third power output end 420a is an axial extension structure of the output gear 420, wherein the transmission gear 421 is coaxially fixed on the transmission shaft 4, and the output gear 420 is rotatably mounted on the first power shaft 2 and meshes with the transmission gear 421; when the output gear 420 is assembled on the first power shaft 2, the third power output end 420a is extended out of the housing 1, and the third power output end 420a is used to connect the crankset of the bicycle, etc., to provide power for the wheels; this embodiment In this embodiment, the output gear 420 can be assembled to the first power shaft 2 by means of a bearing, and a bearing is also provided between the output gear 420 and the housing 1, so that the rotation of the output gear 420 and the first power shaft 2 do not interfere with each other, and correspondingly, in order to ensure the stable transmission of power, the transmission gear 421 is assembled on the transmission shaft 4 by means of a spline connection, so that the rotation of the transmission shaft 4 can drive the transmission gear 421 to rotate together; the transmission gear 421 and the output gear 420 are meshed with each other, so that the direction of the third power output terminal 420a is opposite to the direction of the transmission shaft 4, which can be specifically compared with the first power output terminal 401 on the transmission shaft 4 in the first embodiment. In this embodiment, due to the setting of the second reversing gear set 42, the reversing purpose of the third power output terminal 420a is achieved. In summary, the power of this embodiment is provided via the power input 201 ends fixed at both ends of the first power shaft 2, driving the first power shaft 2 to rotate, and is transmitted to the transmission shaft 4 through the multi-stage driving wheel set 7 and the multi-stage driven wheel set 8. The torque and speed after multi-stage speed change are transmitted to the transmission gear 421 through the transmission shaft 4, and the transmission gear 421 is meshed with the output gear 420 to achieve reversing, and finally transmitted through the third power output end 420a fixed on the output gear 420.

[0137] Embodiment 4:

[0138] This embodiment only describes the differences from the first embodiment. Fig. 22The mid-speed transmission system includes a second power shaft 22 and a support shaft 21 that is at least partially hollow. The support shaft 21 can be rotatably installed in the housing 1 and is used to assemble the multi-stage driving wheel set 7 and the first shift mechanism 3. The function of the support shaft 21 of this embodiment is equivalent to the first power shaft 2 in the first embodiment. The difference is that the two ends of the support shaft 21 of this embodiment do not extend out of the housing 1, and the two ends of the second power shaft 22 extend out of the housing 1 and are provided with a second power input end 221 for connecting to the pedals to provide power for the mid-speed transmission system. Correspondingly, a coaxially assembled input gear 220 is provided on the second power shaft 22. The input gear 220 is used to mesh with any stage of the multi-stage driving wheel set 7. When the power drives the second power shaft 22 to rotate through the second power input end 221, the input gear 220 is connected to any stage of the multi-stage driving wheel set 7. The first-stage external meshing makes the steering of the multi-stage driving wheel set 7 opposite to the steering of the second power shaft 22. Since the multi-stage driving wheel set 7 also needs to mesh with the multi-stage driven wheel set 8 to transmit power, a second steering change is performed here, and finally the steering of the first power output end 401 is the same as the steering of the second power input end 221. In this embodiment, the second power shaft 22 and the support shaft 21 with different axes are set, and the input gear 220 assembled on the second power shaft 22 is meshed with the multi-stage driving wheel set 7 on the support shaft 21 to achieve the steering change, so that the steering of the first power output end 401 is the same as the steering of the second power input end 221, which is different from the form in which the steering of the first power output end 401 is opposite to the steering of the first power input end 301 in the first embodiment, so that the mid-mounted transmission system can provide more diverse steering outputs.

[0139] To achieve one, part, or all of the above purposes or other purposes, the present invention further provides a bicycle comprising the above-mentioned mid-mounted transmission system.

[0140] Obviously, the embodiments described above are only some embodiments of the present invention, rather than all embodiments. The preferred embodiments of the present invention are given in the accompanying drawings, but they do not limit the patent scope of the present invention. The present invention can be implemented in many different forms. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive. Although the present invention has been described in detail with reference to the aforementioned embodiments, for those skilled in the art, it is still possible to modify the technical solutions recorded in the aforementioned specific implementation methods, or to replace some of the technical features therein with equivalents. Any equivalent structure made using the contents of the specification and drawings of the present invention, directly or indirectly used in other related technical fields, is also within the scope of patent protection of the present invention.

Claims

1. A mid-mounted transmission system, characterized in that: include: A housing, a first power shaft that is at least partially hollow, a first shift mechanism, a transmission shaft that is at least partially hollow, a second shift mechanism, a first planetary gear set, a multi-stage driving wheel set, and a multi-stage driven wheel set; The first power shaft and the transmission shaft can both be rotatably connected to the housing, and the first power shaft has a first power input end with both ends extending out of the housing, and the transmission shaft has a first power output end with one end extending out of the housing; The inner gear ring of the first planetary gear set is fixed on the housing, and the sun gear is rotatably arranged on the first power shaft; a plurality of first planetary gears are fixedly connected to the multi-stage driving gear set to form a first amplifying gear set; The multi-stage driving wheel set is rotatably arranged on the first power shaft; A first clutch transmission assembly is provided between the first power shaft and the sun gear, and a second clutch transmission assembly is provided between the first power shaft and the first amplifying wheel set; The multi-stage driven wheel set is rotatably arranged on the transmission shaft, and a third clutch transmission assembly is arranged between the transmission shaft and each stage of the multi-stage driven wheel set; The first shift mechanism has a movable first limit shaft extending into the first power shaft, and the second shift mechanism has a movable second limit shaft extending into the transmission shaft; both the first limit shaft and the second limit shaft have a shift convex portion; The first shifting mechanism can drive the first limiting shaft so that its shifting protrusion abuts against the first clutch transmission assembly to achieve a transmission connection between the first power shaft and the sun gear, or drive the first limiting shaft so that its shifting protrusion abuts against the second clutch transmission assembly to achieve a transmission connection between the first power shaft and the first amplifying wheel group; the second shifting mechanism can drive the second limiting shaft so that its shifting protrusion abuts against any of the third clutch transmission assemblies to achieve a transmission connection between the corresponding driven wheel and the transmission shaft.

2. The mid-mounted transmission system according to claim 1, characterized in that: The multi-stage driving wheel set includes a second planetary gear set, a second driving wheel, a third driving wheel and an axial connection structure; the multi-stage driven wheel set includes a first driven wheel, a second driven wheel and a third driven wheel; The second planetary gear set includes a planet carrier, a plurality of second planetary gears and a first driving wheel; the first driving wheel is provided with a connecting portion in the axial direction, and an inner tooth portion is provided on the inner wall of the first driving wheel; the planet carrier is rotatably arranged on the first power shaft, and the plurality of second planetary gears mesh with the inner tooth portion of the first driving wheel to form a second amplifying wheel set; A fourth clutch transmission assembly is provided between the first power shaft and the planetary carrier; the first shift mechanism can drive the first limit shaft to make its shift convex portion abut against the fourth clutch transmission assembly so that the first power shaft is in transmission connection with the planetary carrier of the second planetary gear set; The second driving wheel is mounted on the connecting portion and is coaxially fixed to the first driving wheel; The third driving wheel, the first driving wheel and the plurality of second planetary wheels of the first planetary gear set are connected via an axial connection structure; the third driving wheel is connected to the first power shaft via a first clutch assembly; The first driving wheel is meshed with the first driven wheel, the second driving wheel is meshed with the second driven wheel, and the third driving wheel is meshed with the third driven wheel.

3. The mid-mounted transmission system according to claim 2, characterized in that: The first power shaft and the transmission shaft are both provided with mounting holes; the first clutch transmission assembly, the second clutch transmission assembly and the fourth clutch transmission assembly are all composed of a first pawl and a second ratchet structure, the first pawl is connected with a spring sheet, and the first pawl is assembled into the mounting hole through the spring sheet, the first ratchet structure is arranged on the sun gear of the first planetary gear set, the third driving gear and the planetary carrier of the second planetary gear set, the first pawl is compressed by the spring sheet and is in a contracted state when not abutted by the shifting protrusion, and is not connected to the corresponding first ratchet structure; the first pawl is in an extended state when abutted by the shifting protrusion, and can be transmission-connected to the corresponding first ratchet structure, and an avoidance space is formed between the first pawl and the mounting hole; The third clutch transmission assembly is composed of a second pawl and a second ratchet structure, the second pawl is connected to a spring sheet, and the second pawl is assembled into the mounting hole through the spring sheet, the second ratchet structure is arranged on each level of the multi-stage slave wheel group, the second pawl is compressed by the spring sheet and is in a contracted state when not abutted by the shift protrusion, and is not connected to the corresponding second ratchet structure; the second pawl is in an extended state when abutted by the shift protrusion, and can be transmission-connected to the corresponding second ratchet structure, and there is no avoidance space between the outer wall of the second pawl and the inner wall of the mounting hole.

4. The mid-mounted transmission system according to claim 2, characterized in that: The first shift mechanism and the second shift mechanism both include a control module and a control motor; Axially extending threaded holes are provided inside the first power shaft and the transmission shaft; The outer walls of the first limiting shaft and the second limiting shaft are both provided with external threads threadedly connected to the threaded hole; The first limiting shaft and the second limiting shaft are both provided with axially penetrating connection holes, the connection holes are connected to the rotating shaft of the control motor, and the screw can move along the axial direction of the rotating shaft of the control motor; The control module is electrically connected to the control motor.

5. The mid-mounted transmission system according to claim 3, characterized in that: The first pawl and the second pawl are both provided with grooves connected to the spring sheet, and the first pawl and the second pawl are provided with transition inclined walls, which can abut against the transition inclined walls when the shifting protrusion moves axially.

6. The mid-mounted transmission system according to claim 2, characterized in that: The connecting portion is an axial protrusion connected to the first driving wheel, and a spline is arranged on the outer wall of the axial protrusion.

7. The mid-mounted transmission system according to claim 3, characterized in that: The second planetary gear set also includes a cylindrical gear; When the plurality of planetary gears of the second planetary gear set are assembled on the planet carrier, the ratchet structure of the second planetary gear and the planet carrier are staggered in the axial direction; The spur gear is fixedly arranged on the housing, and the spur gear is meshed with a plurality of second planetary gears of the second planetary gear set.

8. The mid-mounted transmission system according to claim 7, characterized in that: The housing comprises a left cover, a right cover and a middle housing with openings at both ends; One end of the first power shaft passes through the left cover and is connected to the left cover through a bearing, and the other end passes through the right cover and is connected to the right cover through a bearing; One end of the transmission shaft is connected to the left cover through a bearing, and the other end passes through the right cover and is connected to the right cover through a bearing; The left cover is sealedly connected to an opening at one end of the middle shell, and the right cover is sealedly connected to an opening at the other end of the middle shell.

9. The mid-mounted transmission system according to claim 8, characterized in that: It also includes a first reversing gear set, which includes a plurality of reversing planetary gears, a transmission frame and an output cylinder; The transmission frame is provided with an axially displaced internal gear ring and a connecting ring, and the transmission frame is fixed to the transmission shaft through the connecting ring; A plurality of reversing planetary gears are mounted on the housing, and the reversing planetary gears are meshed with the inner gear ring; The output cylinder is rotatably mounted on the transmission shaft, and one end of the output cylinder is provided with an external tooth portion for meshing with the reversing planetary gear, and the other end of the output cylinder passes through the housing and is provided with a second power output end.

10. A mid-mounted transmission system, characterized in that: include: A housing, a first power shaft that is at least partially hollow, a first shift mechanism, a transmission shaft that is at least partially hollow, a second shift mechanism, a first planetary gear set, a multi-stage driving gear set, a multi-stage driven gear set, and a second reversing gear set; The first power shaft and the transmission shaft can both be rotatably connected to the housing, and the first power shaft has a first power input end with both ends extending out of the housing; The second reversing gear set comprises a transmission gear and an output gear, wherein the transmission gear is coaxially fixed on the transmission shaft, and the output gear is rotatably mounted on the first power shaft and meshes with the transmission gear; The output gear is provided with an axially extending power output end, and the power output end is arranged outside the housing; The inner gear ring of the first planetary gear set is fixed on the housing, and the sun gear is rotatably arranged on the first power shaft; a plurality of first planetary gears are fixedly connected to the multi-stage driving gear set to form a first amplifying gear set; The multi-stage driving wheel set is rotatably arranged on the first power shaft; A first clutch transmission assembly is provided between the first power shaft and the sun gear, and a second clutch transmission assembly is provided between the first power shaft and the first amplifying wheel set; The multi-stage driven wheel set is rotatably arranged on the transmission shaft, and a third clutch transmission assembly is arranged between the transmission shaft and each stage of the multi-stage driven wheel set; The first shift mechanism has a movable first limit shaft extending into the first power shaft, and the second shift mechanism has a movable second limit shaft extending into the transmission shaft; both the first limit shaft and the second limit shaft have a shift convex portion; The first shifting mechanism can drive the first limiting shaft so that its shifting protrusion abuts against the first clutch transmission assembly to achieve a transmission connection between the first power shaft and the sun gear, or drive the first limiting shaft so that its shifting protrusion abuts against the second clutch transmission assembly to achieve a transmission connection between the first power shaft and the first amplifying wheel group; the second shifting mechanism can drive the second limiting shaft so that its shifting protrusion abuts against any of the third clutch transmission assemblies to achieve a transmission connection between the corresponding driven wheel and the transmission shaft.

11. A mid-mounted transmission system, characterized in that: include: A housing, an at least partially hollow support shaft, a first shift mechanism, an at least partially hollow transmission shaft, a second shift mechanism, a first planetary gear set, a multi-stage driving wheel set, a multi-stage driven wheel set, and a second power shaft; The second power shaft, the support shaft and the transmission shaft are all rotatably connected to the housing, and the second power shaft has a second power input end with both ends extending out of the housing, and the transmission shaft has a power output end with one end extending out of the housing; the second power shaft has a coaxially assembled input gear; The inner gear ring of the first planetary gear set is fixed on the housing, and the sun gear is rotatably arranged on the support shaft; a plurality of first planetary gears are fixedly connected to the multi-stage driving gear set to form a first amplifying gear set; The multi-stage driving wheel set is rotatably arranged on the support shaft; any stage of the multi-stage driving wheel set can be meshed with the input gear; A first clutch transmission assembly is provided between the support shaft and the sun gear, and a second clutch transmission assembly is provided between the support shaft and the first amplifying wheel set; The multi-stage driven wheel set is rotatably arranged on the transmission shaft, and a third clutch transmission assembly is arranged between the transmission shaft and each stage of the multi-stage driven wheel set; The first shift mechanism has a movable first limit shaft extending into the interior of the support shaft, and the second shift mechanism has a movable second limit shaft extending into the interior of the transmission shaft; both the first limit shaft and the second limit shaft have a shift convex portion; The first shifting mechanism can drive the first limiting shaft so that its shifting protrusion abuts against the first clutch transmission component to achieve a transmission connection between the support shaft and the sun gear, or drive the first limiting shaft so that its shifting protrusion abuts against the second clutch transmission component to achieve a transmission connection between the support shaft and the first amplifying wheel group; the second shifting mechanism can drive the second limiting shaft so that its shifting protrusion abuts against any of the third clutch transmission components to achieve a transmission connection between the corresponding driven wheel and the transmission shaft.

12. A bicycle, characterized in that: The bicycle comprises the mid-mounted transmission system according to any one of claims 1 to 11.

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