Middle-mounted speed control system and bicycle

Abstract

The utility model relates to the technical field of speed control systems, and discloses a middle speed control system and a bicycle. A shell of the middle speed control 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 planet wheels are fixedly connected with the multi-stage driving wheel set to form a first amplification wheel set; 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 amplification wheel set. The multi-stage driven wheel set is rotationally 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. A gear shifting protruding part of the first gear shifting mechanism abuts against the first clutch transmission assembly or the second clutch transmission assembly so that the first power shaft can be in transmission connection with the sun gear or the first amplification wheel set. The gear shifting protruding part of the second gear shifting mechanism abuts against any third clutch transmission assembly so that the corresponding driven wheel can be in transmission connection with the transmission shaft.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of the middle speed change system of bicycle, especially to a middle speed change system. BACKGROUND

[0002] The speed change type of bicycle is generally divided into derailleur, hub gear and middle speed changer. The derailleur is external, is particularly easy to damage, is easy to drop the chain and is difficult to maintain. The hub gear is maintenance-free, but the speed change mechanism is very complex and particularly heavy, and the weight is distributed on the rear wheel, so that it is particularly difficult to change the tire, the riding experience is not good and it is not widely used. The middle speed changer is set in the middle of the bicycle, which is most consistent with the distribution of gravity. However, the middle speed changer is rare on the market, and the existing speed change box of the middle speed changer is only a simple gear arranged side by side, so that the more the speed change levels are, the more the gears are, and the heavier the weight is. In order to promote the iteration of bicycle technology, it is urgent to have a middle speed changer box with compact structure, wide speed change range, light weight and simple speed change structure. SUMMARY

[0003] Therefore, the utility model provides a middle speed change system to solve the technical problems in the above background.

[0004] In order to achieve one or part or all of the above purposes or other purposes, the utility model provides a middle speed change system, which comprises a shell, a first power shaft which is at least partially hollow, a first gear shifting mechanism, a transmission shaft which is at least partially hollow, a second gear shifting 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 are both rotatably connected to the shell, and the first power shaft has a first power input end which extends out of the shell at both ends, and the transmission shaft has a first power output end which extends out of the shell at one end.

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

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

[0008] The first clutch transmission assembly is arranged between the first power shaft and the sun gear, and the second clutch transmission assembly is arranged between the first power shaft and the first amplification wheel set.

[0009] The multi-stage driven wheel set is rotatably arranged on the transmission shaft, and the 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 limiting shaft extending into the first power shaft, and the second shift mechanism has a movable second limiting shaft extending into the transmission shaft; the first limiting shaft and the second limiting shaft each have a shift protrusion;

[0011] The first shift mechanism can drive the first limiting shaft to make the shift protrusion abut against the first clutch transmission assembly to make the first power shaft and the sun gear in transmission connection, or drive the first limiting shaft to make the shift protrusion abut against the second clutch transmission assembly to make the first power shaft and the first amplification gear set in transmission connection; the second shift mechanism can drive the second limiting shaft to make the shift protrusion abut against any one of the third clutch transmission assemblies to make the corresponding driven gear and the transmission shaft in transmission connection.

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

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

[0014] The fourth clutch transmission assembly is arranged between the first power shaft and the planet carrier; the first shift mechanism can drive the first limiting shaft to make the shift protrusion abut against the fourth clutch transmission assembly to make the first power shaft and the planet carrier in transmission connection;

[0015] The second driving gear is coaxially fixed on the connecting portion of the first driving gear;

[0016] The third driving gear, the first driving gear and the plurality of second planetary gears are connected through the axial connection structure; the third driving gear is connected with the first power shaft through the first clutch assembly;

[0017] The first driving gear is in mesh with the first driven gear, the second driving gear is in mesh with the second driven gear, and the third driving gear is in mesh with the third driven gear.

[0018] Preferably, the first power shaft and the transmission shaft are both provided with mounting holes; the first, second and fourth clutch transmission assemblies are all formed by a first pawl and a second ratchet structure, the first pawl is connected with an elastic sheet, and the first pawl is assembled into the mounting hole through the elastic sheet; the first ratchet structure is arranged on the sun gear of the first planetary gear set, the third driving wheel and the carrier of the second planetary gear set; the first pawl is compressed by the elastic sheet to be in a retracted state when not being abutted by the shift protrusion, and is not connected with the corresponding first ratchet structure; the first pawl is in an extended state when being abutted by the shift protrusion, and is in driving connection with the corresponding first ratchet structure, and a relief space is formed between the first pawl and the mounting hole;

[0019] The third clutch transmission assembly is formed by a second pawl and a second ratchet structure, the second pawl is connected with an elastic sheet, and the second pawl is assembled into the mounting hole through the elastic sheet; the second ratchet structure is arranged on each level of the multi-stage driven gear set; the second pawl is compressed by the elastic sheet to be in a retracted state when not being abutted by the shift protrusion, and is not connected with the corresponding second ratchet structure; the second pawl is in an extended state when being abutted by the shift protrusion, and is in driving connection with the corresponding second ratchet structure, and there is no relief space between the outer wall of the second pawl and the inner wall of the mounting hole.

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

[0021] The first power shaft and the transmission shaft are both provided with a threaded hole extending in the axial direction;

[0022] The outer wall of the first and second limiting shafts is both provided with an external thread in threaded connection with the threaded hole;

[0023] The first and second limiting shafts are both provided with a connecting hole extending in the axial direction, the connecting hole is connected with the rotating shaft of the control motor, and the screw rod can move along the axial direction of the rotating shaft of the control motor;

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

[0025] Preferably, the first and second pawls are both provided with a groove connected with the elastic sheet, and the first and second pawls are both provided with a transition inclined wall, which can be abutted by the shift protrusion when the shift protrusion moves in the axial direction.

[0026] Preferably, the connecting part is an axial protrusion connected with the first driving wheel, and the outer wall of the axial protrusion is provided with a spline.

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

[0028] When the plurality of second planet gears of the second planetary gear set are assembled on the planet carrier, the second planet gears and the ratchet structure of the planet carrier are arranged axially staggered with each other;

[0029] The cylindrical gear is fixed on the housing and meshes with the plurality of second planet gears of the second planetary gear set.

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

[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 and the middle housing are sealingly connected at one end, and the right cover and the middle housing are sealingly connected at the other end.

[0034] Preferably, it further comprises a first reversing gear set, the first reversing gear set comprising a plurality of reversing planet gears, a transmission carrier and an output cylinder;

[0035] The transmission carrier is provided with an axially staggered inner ring and a connecting ring, and the transmission carrier is fixed to the transmission shaft through the connecting ring;

[0036] The plurality of reversing planet gears are mounted on the housing and mesh with the inner ring;

[0037] The output cylinder is rotatably mounted on the transmission shaft, one end of the output cylinder is provided with an outer tooth part for meshing with the reversing planet gears, 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, comprising: a housing, a first power shaft which is at least partially hollow, a first gear shifting mechanism, a transmission shaft which is at least partially hollow, a second gear shifting mechanism, a first planetary gear set, a plurality of primary gear sets, a plurality of driven gear sets and a second reversing gear set;

[0039] The first power shaft and the transmission shaft are both rotatably connected to the housing, and the first power shaft has a first power input end which extends out of the housing at both ends;

[0040] The second reversing gear set comprises a transmission gear and an output gear, the transmission gear is coaxially fixed on the transmission shaft, 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 which extends out of the housing;

[0041] The inner 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 with the multi-stage driving gear set to form a first amplification gear set;

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

[0043] The first power shaft and the sun gear are provided with a first clutch transmission assembly, and the first power shaft and the first amplification gear set are provided with a second clutch transmission assembly;

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

[0045] The first shift mechanism has a movable first limiting shaft extending into the interior of the first power shaft, and the second shift mechanism has a movable second limiting shaft extending into the interior of the transmission shaft; the first limiting shaft and the second limiting shaft each have a shift protrusion;

[0046] The first shift mechanism can drive the first limiting shaft to make the shift protrusion abut against the first clutch transmission assembly to make the first power shaft and the sun gear in transmission connection, or drive the first limiting shaft to make the shift protrusion abut against the second clutch transmission assembly to make the first power shaft and the first amplification gear set in transmission connection; the second shift mechanism can drive the second limiting shaft to make the shift protrusion abut against any one of the third clutch transmission assemblies to make the corresponding driven gear and the transmission shaft in transmission connection.

[0047] A middle-mounted variable speed system, comprising: a housing, a support 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 gear set, a multi-stage driven gear set and a second power shaft;

[0048] 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 which extends out of the housing at both ends, and the transmission shaft has a power output end which extends out of the housing at one end; the second power shaft has a coaxially assembled input gear;

[0049] The inner 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 with the multi-stage driving gear set to form a first amplification gear set;

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

[0051] The first clutch transmission assembly is arranged between the support shaft and the sun gear, and the second clutch transmission assembly is arranged between the support shaft and the first amplification wheel set;

[0052] The third clutch transmission assembly is arranged between the transmission shaft and each level of the multi-level driven wheel set.

[0053] The first shift mechanism has a movable first limiting shaft extending into the support shaft, and the second shift mechanism has a movable second limiting shaft extending into the transmission shaft; the first limiting shaft and the second limiting shaft each have a shift protrusion.

[0054] The first shift mechanism can drive the first limiting shaft to make the shift protrusion abut against the first clutch transmission assembly to make the support shaft and the sun gear in transmission connection, or drive the first limiting shaft to make the shift protrusion abut against the second clutch transmission assembly to make the support shaft and the first amplification wheel set in transmission connection; the second shift mechanism can drive the second limiting shaft to make the shift protrusion abut against any one of the third clutch transmission assemblies to make the corresponding driven wheel and the transmission shaft in transmission connection.

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

[0056] The embodiment of the present application has the following beneficial effects:

[0057] After the above scheme is adopted, since the core transmission components of the mid-mounted speed change system only include the first planetary gear set, the multi-level driving wheel set and the multi-level driven wheel set, the transmission process is adjusted by the first limiting shaft arranged in the first power shaft and the second limiting shaft arranged in the transmission shaft, the multi-level driving wheel set and the multi-level driven wheel set are directly in transmission, no additional space is needed to arrange the transmission gear set and the speed change gear set, the transmission process is optimized, and the speed change box structure of the bicycle is simplified, and the weight and volume can be made smaller. BRIEF DESCRIPTION OF DRAWINGS

[0058] In order to more clearly illustrate the technical scheme in the embodiments of the present application or the prior art, the drawings needed in the embodiment or the prior art description will be briefly introduced below, and obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creating any creative labor.

[0059] Among them:

[0060] Figure 1 It is an overall structure schematic view of the first embodiment;

[0061] Figure 2This is an exploded view of the overall structure of Example 1;

[0062] Figure 3 This is a cross-sectional view of the overall structure of Embodiment 1;

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

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

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

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

[0067] Figure 8 This is a schematic diagram of the shell-less structure of Example 1;

[0068] Figure 9 This is a schematic diagram showing the separation of the first power shaft section in Embodiment 1;

[0069] Figure 10 This is a schematic diagram showing the disassembled structure of the drive shaft section in Embodiment 1;

[0070] Figure 11 This is an exploded view of the second planetary gear set in Embodiment 1;

[0071] Figure 12 This is a schematic diagram of the structure of the first planetary gear set in Embodiment 1;

[0072] Figure 13 This is a schematic diagram of the first gear shifting mechanism in Embodiment 1;

[0073] Figure 14 This is a schematic diagram of the first pawl and the first power shaft, and the second pawl and the transmission shaft in Embodiment 1;

[0074] Figure 15 This is a cross-sectional view of the first and second pawls during assembly in Embodiment 1;

[0075] Figure 16 This is a schematic diagram of the structure of the second pawl and spring in Embodiment 1;

[0076] Figure 17 This is a schematic diagram of the structure of the first reversing gear set in Embodiment 2. Figure 1 ;

[0077] Figure 18 Schematic diagram of the first reversing gear set for implementation two. Figure 2 ;

[0078] Figure 19 Structure diagram of the embodiment three with the second reversing gear set;

[0079] Figure 20 Structure diagram of the embodiment three with the second reversing gear set;

[0080] Figure 21 Structure diagram of the embodiment three with the second reversing gear set;

[0081] Figure 22 Structure diagram of the embodiment four.

[0082] Reference signs:

[0083] 1, housing; 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 gear shifting mechanism; 301, first limiting shaft; 301a, gear shifting convex part; 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 tooth ring; 411b, connecting ring; 412, output cylinder; 412a, outer tooth part; 412b, second power output end; 42, second reversing gear set; 420, output gear; 420a, third power output end; 421, transmission gear;

[0087] 5, second gear shifting mechanism; 501, second limiting shaft;

[0088] 6, first planetary gear set; 601, sun gear; 602, inner ring gear; 603, first planetary gear;

[0089] 7, multi-stage driving wheel set; 70, second planetary gear set; 702, planetary carrier; 703, second planetary gear; 704, cylindrical gear; 71, first driving wheel; 710, connecting part; 711, inner tooth part; 712, connecting lug; 72, second driving wheel; 73, third driving wheel; 74, axial connecting structure; 740, limiting rod; 741, limiting 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, elastic sheet. DETAILED DESCRIPTION

[0092] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used in the description herein is for describing particular embodiments only and is not intended to be limiting of the application; the description herein and the claims of the application and the accompanying drawings are not intended to limit the application to the specific embodiments presented but encompass all changes, equivalents, and substitutes that are within the spirit of the application. The description herein and the claims of the application and the accompanying drawings are not intended to limit the application to the specific embodiments presented but encompass all changes, equivalents, and substitutes that are within the spirit of the application. The terms "comprising", "having", "including", and "containing" used herein are meant to encompass the presence of stated features, integers, steps, operations, elements, components, or the like, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or the like.

[0093] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily mutually exclusive of other embodiments. It is expressly understood that the embodiments described herein are merely examples from a whole class of comparable embodiments which those skilled in the art will readily appreciate. It is also expressly understood that the description herein and the claims that follow are intended to cover all such variations as fall within the scope of the application. It should be noted that features explained as if they were implemented only in one embodiment can be implemented in other embodiments.

[0094] In order to make the technical personnel in the art better understand the application scheme, the technical solutions in the embodiments of the application will be clearly and completely described below in conjunction with the drawings.

[0095] Embodiment one:

[0096] As shown in the accompanying drawings Figures 1-16 The application embodiment provides a middle-mounted variable speed system, which comprises a shell 1, a first power shaft 2 which is at least partially hollow, a first gear shifting mechanism 3, a transmission shaft 4 which is at least partially hollow, a second gear shifting 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 are both rotatably connected to the shell 1, and the first power shaft 2 has a first power input end 201 which extends out of the shell 1 at both ends, and the transmission shaft 4 has a first power output end 401 which extends out of the shell 1 at one end.

[0098] The inner 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 with the multi-stage driving gear set 7 to form a first amplification gear set;

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

[0100] The first power shaft 2 and the sun gear 601 are provided with a first clutch transmission assembly, and the first power shaft 2 and the first amplification gear set are provided with a second clutch transmission assembly;

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

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

[0103] The first shift mechanism 3 can drive the first limiting shaft 301 to make the shift protrusion 301a abut against the first clutch transmission assembly to make the first power shaft 2 and the sun gear 601 in transmission connection, or drive the first limiting shaft 301 to make the shift protrusion 301a abut against the second clutch transmission assembly to make the first power shaft 2 and the first amplification gear set in transmission connection; the second shift mechanism 5 can drive the second limiting shaft 501 to make the shift protrusion 301a abut against any third clutch transmission assembly to make the corresponding driven gear and the transmission shaft 4 in transmission connection.

[0104] In the embodiment, the first power shaft 2 has two first power input ends 201 extending out of the housing 1, both of which are used to connect the bicycle crank and the pedal, and the transmission shaft 4 has a first power output end 401 extending out of the housing 1, which is used to connect the bicycle chainring, and the chainring is in transmission to the wheel through the chain or other forms. The multi-stage driving gear set 7 and the multi-stage driven gear set 8 can be a combination of a plurality of gears of different sizes or specifications, for example, the multi-stage driving gear set 7 is a combination of three gears of different sizes, and the multi-stage driven gear set 8 is a combination of three gears of different sizes, each of which corresponds to a stage, such as Figure 6 and Figure 7The first planetary gear set 6 and the multi-stage driving gear set 7 are fixedly connected to form a first amplification gear set. The sun gear 601 of the first planetary gear set 6 is coaxially arranged on the first power shaft 2. The multi-stage driving gear set 7 and the plurality of first planetary gears 603 between the sun gear 601 and the ring gear 602 are fixedly connected to form an amplification gear set as a whole. In use, the sun gear 601 drives the plurality of first planetary gears 603 to rotate, thereby driving the multi-stage driving gear set 7 to rotate. The power is transmitted through the first power input end 201 of the first power shaft 2, amplified by the plurality of first planetary gears 603, and drives the multi-stage driving gear set 7 to rotate. At this time, the multi-stage driving gear set 7 provides a first input speed for the multi-stage driven gear set 8. Correspondingly, the multi-stage driving gear 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 gear set 7. That is, the multi-stage driving gear set 7 provides a second input speed for the multi-stage driven gear set 8, and the second input speed is different from the first input speed.

[0105] The multi-stage driven gear set 8 is rotatably arranged on the transmission shaft 4. Correspondingly, each gear of the multi-stage driven gear set 8 is independent when rotating. The first clutch transmission assembly, the second clutch transmission assembly, and the third clutch transmission assembly are assemblies that can separate or connect the transmission. They can be the ratchet 90 structure as described later, or other forms, for example, two friction plates. The engagement or separation of the two friction plates is controlled by the shift protrusion 301a to control the separation or connection of the transmission.

[0106] Referring to the drawings Figure 3 - Figure 8During operation, if the first shifting mechanism 3 drives the first limiting shaft 301 to make its shifting protrusion 301a abut against the first clutch transmission assembly, thereby connecting the first power shaft 2 with the sun gear 601 of the first planetary gear set 6, then the first amplifying gear set is not connected to the first power shaft 2. 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, it drives the multi-stage driving gear set 7 to rotate. The second shifting mechanism 5 drives the second limiting shaft 501 to make its shifting protrusion 301a abut against the third clutch transmission assembly that needs to be output, thereby connecting its corresponding driven gear with the transmission shaft 4. Taking the shifting protrusion 301a of the second limiting shaft 501 abutting against the first gear on the left in the multi-stage driven gear set 8 as an example, at this time, the power is transmitted from the first gear on the left in the multi-stage driving gear set 7 to the first gear on the left in the multi-stage driven gear set 8, and then to the transmission shaft 4, finally driving the chainring connected to the first power output end 401 to output. Although all stages of the multi-stage driving gear set 7 and the multi-stage driven gear set 8 are engaged in the above transmission process, only the first gear on the left side of the multi-stage driven gear set 8 has a transmission relationship with the transmission shaft 4. The other gears on the multi-stage driven gear set 8 are idle and do not affect the transmission process. If the first shifting mechanism 3 drives the first limiting shaft 301 to make its shifting protrusion 301a abut against the second clutch transmission assembly, thus connecting the first power shaft 2 with the first amplifying gear set; 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 gear set 7 to rotate. The second shifting mechanism 5 drives the second limiting shaft 501 to make its shifting protrusion 301a abut against the third clutch transmission assembly that needs to be output, thus connecting its corresponding driven gear with the transmission shaft 4. Taking the shifting protrusion 301a of the second limiting shaft 501 abutting against the first gear on the left in the multi-stage driven gear set 8 as an example, at this time the power is transmitted from the first gear on the left in the multi-stage driving gear set 7 to the first gear on the left in the multi-stage driven gear set 8 and then to the transmission shaft 4, finally driving the chainring connected to the first power output end 401 of the transmission shaft 4 to output. Although all stages of the multi-stage driving gear set 7 and the multi-stage driven gear set 8 are engaged in the above transmission process, only the first gear on the left side of the multi-stage driven gear set 8 has a transmission relationship with the transmission shaft 4. The other gears on the multi-stage driven gear set 8 are idle. Similarly, the sun gear 601 of the first planetary gear set 6 does not have a transmission relationship with the first power shaft 2, and the sun gear 601 is also idle, which does not affect the transmission process.

[0107] In summary, when the multi-stage driving wheel set 7 and the multi-stage driven wheel set 8 are both three-stage, the first power shaft 2 is connected with the sun gear 601 or the first amplification 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 each stage of the three-stage driven wheel set connected with the transmission shaft 4 can obtain a different output speed, and the whole system can provide 2x3=6 different speeds. Similarly, when the multi-stage driving wheel set 7 and the multi-stage driven wheel set 8 are both four-stage, 2x4=8 different speeds can be provided. Other stages are the same, and will not be repeated.

[0108] Referring to the accompanying drawings Figure 9 and Figure 11 The multi-stage driving wheel set 7 comprises 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 comprises a first driven wheel 801, a second driven wheel 802 and a third driven wheel 803;

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

[0110] The fourth clutch transmission assembly is arranged between the first power shaft 2 and the planet carrier 702; the first shift mechanism 3 can drive the first limiting shaft 301 to make the shift protrusion 301a of the first limiting shaft 301 abut against the fourth clutch transmission assembly, so that the first power shaft 2 is in transmission connection with the planet carrier 702;

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

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

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

[0114] Specifically, the connecting portion 710 is arranged in the axial direction of the first driving wheel 71, and the connecting portion 710 can be specifically a protrusion in the axial direction of the first driving wheel 71, and the outer wall of the protrusion in the axial direction is provided with a spline. 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. The third driving wheel 73 is fixedly connected to the plurality of first planet wheels 603 of the first planetary gear set 6 and the first driving wheel 71 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 the embodiment, the first amplification wheel set is specifically an amplification wheel set formed by connecting the plurality of first planet wheels 603 of the first planetary gear set 6 and the third driving wheel 73. Correspondingly, the second clutch transmission assembly is used to connect the third driving wheel 73 and the first power shaft 2. In order to provide more speed adjustment options for the middle-mounted variable speed system based on the three-level driving wheel, the planetary carrier 702 and the plurality of second planet wheels 703 are further arranged in the first driving wheel 71. The planetary 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. The planetary carrier 702 has a plurality of extension arms for mounting the plurality of second planet wheels 703. The plurality of second planet wheels 703 are engaged with the inner tooth portion 711 of the first driving wheel 71 to form a second amplification wheel set. When the shift protrusion 301a of the first limiting shaft 301 moves to the position of the fourth clutch transmission assembly, the fourth clutch transmission assembly connects the planetary carrier 702 and the first power shaft 2. At this time, power is transmitted to the first driving wheel 71 through the first power input end 201 of the first power shaft 2, the planetary carrier 702 and the plurality of second planet wheels 703, so as to provide the third input speed for the multi-stage driving wheel set 7 to the multi-stage driven wheel set 8. It should be noted that the system can provide different speed adjustment options by setting the size relationship between the radius R1 of the revolution circle of the plurality of first planet wheels 603 and the radius R2 of the revolution circle of the plurality of second planet wheels 703. The specific setting can be made according to the actual speed adjustment requirement. For example, when the radius R1 of the revolution circle of the plurality of first planet wheels 603 of the first planetary gear set 6 is smaller than the radius R2 of the revolution circle of the plurality of second planet wheels 703 of the second planetary gear set 70, the first input speed of the first amplification wheel set and the second input speed of the second amplification wheel set are different. In summary, when the multi-stage driving wheel set 7 and the multi-stage driven wheel set 8 of the middle-mounted variable speed system are both three levels, the second planetary gear set 70 is arranged in the multi-stage driving wheel set 7, so that the whole system can provide 3x3=9 groups of different speeds, that is, the middle-mounted variable speed 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 wheel set 7, the second planetary gear set 70 further comprises 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 and the planet carrier 702 are connected with the fourth clutch transmission assembly are axially staggered; the cylindrical gear 704 is fixedly arranged on the housing 1, and the cylindrical gear 704 is engaged with the plurality of second planetary gears 703; specifically, the extension arm of the planet carrier 702 is an axially inclined extension structure, as shown in Figure 6 The part of the planet carrier 702 connected with the fourth clutch transmission assembly and the second driving wheel 72 are in the same vertical plane, and the plurality of second planetary gears 703 and the first driving wheel 71 are used to engage with the outer tooth part of the multi-stage driven wheel set 8, which are in the same vertical plane. By fully utilizing the internal space of the first driving wheel 71, more speed output of the mid-mounted transmission system can be improved without increasing the space and volume; and the distance between the fourth clutch transmission assembly and the second clutch transmission assembly is reduced, thereby reducing the movement distance of the first limiting shaft 301, and further optimizing the structural layout inside the first power shaft 2.

[0116] Referring to the accompanying Figure 5 , Figure 6 , Figure 12 , Figure 14 , Figure 15 and Figure 16 , the first clutch transmission assembly, the second clutch transmission assembly and the fourth clutch transmission assembly are all composed of the first pawl 90 and the first ratchet structure 91. The first pawl 90 is connected with the elastic sheet 94, and the first pawl 90 is assembled into the mounting hole 200 through the elastic sheet 94. The first ratchet structure 91 is arranged on the sun gear 601 of the first planetary gear set 6, the third driving wheel 73 and the planet carrier 702 of the second planetary gear set 70. The first pawl 90 is in a retracted state when it is not abutted by the shift protrusion 301a and is compressed by the elastic sheet, and is not connected with the corresponding first ratchet structure 91. The first pawl 90 is in an extended state when it is abutted by the shift protrusion 301a, and can be in driving connection with the corresponding first ratchet structure 91. The first pawl 90 and the mounting hole 200 form a relief space.

[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 with an elastic sheet 94, and the second pawl 92 is assembled into the mounting hole 200 through the elastic sheet 94. The second ratchet structure 93 is arranged on each stage of the multi-stage driven wheel set 8. When the second pawl 92 is not abutted by the shift protrusion 301a, it is compressed by the elastic sheet 94 to be in a retracted state and is not connected with 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 in driving connection with the corresponding second ratchet structure 93. There is no 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 at the same interval. This not only realizes the compactness of the structure distribution, but also enables the first shift mechanism 3 to adopt a simpler instruction to control the movement of the first limiting shaft 301, that is, only the control of the movement of the first limiting shaft 301 by the same distance each time can realize the switching between different clutch transmission assemblies. Similarly, the third clutch transmission assembly is provided with three third clutch transmission assemblies corresponding to the three-stage driven wheel of the multi-stage driven wheel set 8, and the three third clutch transmission assemblies are distributed along the axial direction of the transmission shaft 4 at the same interval, which will not be described 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 arranged on the first power shaft 2 corresponding to the position of the third driving wheel 73. A plurality of first pawls 90 are arranged on the mounting holes 200, and one end of the first pawl 90 is connected with the elastic sheet 94. The other end of the elastic sheet 94 is fixed on the inner wall of the mounting hole 200. When the first pawl 90 is not abutted by the shift protrusion 301a, it is compressed by the elastic sheet 94 to be in a retracted state. When the first pawl 90 is abutted by the shift 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. When the first power shaft 2 rotates in the forward direction as indicated by the arrow, the first pawl 90 is abutted by the shift protrusion 301a to establish driving connection with the first ratchet structure 91 on the third driving wheel 73, thereby driving the third driving wheel 73 to rotate. Figure 15 Figure 15 ​When rotating in the reverse direction of the arrow, the first pawl 90 is retracted into the clearance space due to the clearance between the first pawl 90 and the inner wall of the mounting hole 200, that is, the reverse rotation of the first power shaft 20 cannot drive the third driving wheel 73 to rotate, thereby avoiding the influence of the reverse pedaling of the pedal on the normal use of other transmission structures on the first power shaft 2 and the transmission shaft 4. The principles of the second and fourth clutch assemblies are the same as that of the first clutch assembly, and will not be described herein. The third clutch assembly is different from the above three clutch assemblies, specifically, the second pawl 92 of the third clutch assembly is thicker than the first pawl 91. When the second pawl 92 is assembled into the mounting hole 200 on the transmission shaft 4, the clearance between the second pawl 92 and the mounting hole 200 is only enough for the second pawl 92 to move in the axial direction of the mounting hole 200, and cannot swing in the radial direction, so that the multi-stage driven wheel set 8 can be driven to rotate regardless of the direction of rotation of the transmission shaft 4. Conversely, when the bicycle is on a downhill or sliding, the rotation of the transmission shaft 4 will also drive the multi-stage driven wheel set 8 to rotate, and further drive the multi-stage driving wheel set 7 to rotate. Since the multi-stage driving wheel set 7 is currently in reverse rotation, the first pawl 90 will be retracted into the clearance space due to the extrusion of the first ratchet structure 91, so that the first power shaft 2 will not rotate with the multi-stage driving wheel set 7, thereby 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 one-way rotation, the processing cost of the second pawl 92 is greatly reduced.

[0119] In order to quickly convert the axially distributed first pawl 90 or second pawl 92 to the extended state when the shift protrusion 301a moves axially, a transition inclined wall 921 is arranged on the first pawl 90 and the second pawl 92. The shift protrusion 301a is relatively easy to convert the first pawl 90 or the second pawl 92 to the extended state by abutting against the transition inclined wall 921. In order to facilitate the connection stability between the elastic sheet 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 elastic sheet 94 when not abutting against the shift protrusion 301a, a groove 920 is arranged on the top of the first pawl 90 and the second pawl 92. One end of the elastic sheet 94 is embedded in the groove 921, and the other end of the elastic sheet 94 is fixed on the inner wall of the mounting hole 200.

[0120] Referring to FIGS. 1 to 8, Figure 6 and Figure 13 The first shift mechanism 3 and the second shift mechanism 5 each include a control module 302 and a control motor 303.

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

[0122] The outer wall of the first limiting shaft 301 and the second limiting shaft 501 is provided with external threads which are threadedly connected with the threaded hole 202.

[0123] The first limiting shaft 301 and the second limiting shaft 501 are internally provided with a connecting hole 301b which penetrates in the axial direction and is connected with the rotating shaft of the control motor 303, and the screw rod can move in the axial direction of the rotating shaft of the control motor 303.

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

[0125] Since the first shifting mechanism 3 and the second shifting mechanism 5 adopt the same structure, the first shifting mechanism 3 is described in this embodiment. In order to prevent the first limiting shaft 301 and the rotating shaft of the control motor 303 from rotating relative to each other, the cross section of the connecting hole 301b and the cross section of the rotating shaft of the control motor 303 are hexagonal in this embodiment. When the control motor 303 is started to rotate the rotating shaft, the connecting hole 301b and the rotating shaft of the control motor 303 cannot rotate relative to each other, while the first limiting shaft 301 is threadedly connected with the threaded hole 202 of the first power shaft 2, so that the first limiting shaft 301 moves in the axial direction of the first power shaft 2. In other embodiments, the cross section of the connecting hole 301b and the cross section of 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. The battery 302b and the control board 302a are arranged in the axial direction of the first power shaft 2, and the control board 302a is located at the end 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 external electronic devices. 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 to make the rotating shaft of the control motor 303 rotate in a specified direction and a specified number of turns. For example, the control board 302a sends a first gear position instruction to the control motor 303, so that the first limiting shaft 301 moves, and the shifting protrusion 301a is located at the position of the first clutch transmission assembly, and drives the first clutch transmission assembly to connect with the sun gear 601 of the first planetary gear set 6, establishing the transmission connection between the sun gear 601 of the first planetary gear set 6 and the first power shaft 2. As shown in FIG. Figure 13 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 further provided with a protective shell 302c which wraps the battery 302b and the control board 302a, and an elastic clamping protrusion is arranged at the end of the protective shell 302c to be connected with the first power shaft 2, facilitating the disassembly and assembly of the control module 302 as a whole from the first power shaft 2.

[0126] To ensure the stability and compactness of the connection between the first planetary gear set 6 and the multi-stage driving wheel set 7, the axial connection structure 74 of the embodiment comprises a plurality of limiting rods 740, a plurality of clamping rings 742 and a limiting ring 741; the plurality of limiting rods 740 and the plurality of clamping 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 arranged on the side of the plurality of first planetary gears 603 away from the third driving wheel 73, one end of the limiting rod 740 passes through the first driving wheel 71, the third driving wheel 73, the planetary gear and the limiting ring 741 in sequence, the clamping ring 742 is clamped at the end of the limiting rod 740 and is arranged in close contact with the limiting ring 741, specifically, a plurality of through holes are arranged on the limiting ring 741 corresponding to the plurality of first planetary gears 603 of the first planetary gear set 6, a plurality of connecting ears 712 are arranged on the inner wall of the connecting part 710 of the first driving wheel 71, and a through hole is arranged on the connecting ear 712, and the limiting rod 740 is a T-shaped rod structure, and the smaller-diameter end of the limiting rod 740 is provided with a clamping groove for clamping the clamping ring 742, when assembling, the smaller-diameter end of the limiting rod 740 passes through the connecting ear 712 of the first driving wheel 71, the third driving wheel 73, the first planetary gear 603 and the corresponding position 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 body, and the second driving wheel 72 is limited by the third driving wheel 73 and cannot move axially, so that when the plurality of first planetary gears 603 revolve, the multi-stage driving wheel set 7 can also be driven to rotate.

[0127] In some embodiments, the shell 1 comprises a left cover 102, a right cover 101 and a middle shell 103 with both ends open;

[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 and the middle shell 103 are sealingly connected at one end, and the right cover 101 and the middle shell 103 are sealingly connected at the other end.

[0131] In the embodiment, the transmission structure of the whole mid-mounted variable speed system is sealed in the shell 1, the interface of the first power shaft 2 and the left cover 102 and the right cover 101 can be sealed by using a sealing cover, and a sealing ring is arranged in the sealing cover to further seal. In use, the transmission system can be prevented from being polluted by mud, dust and other objects and even from being affected in use, and the effect of cleaning-free and maintenance-free can be achieved. After the bicycle is installed with the mid-mounted variable speed system, even if the bicycle is ridden on a muddy road, the system will not be damaged due to the entry of foreign matters, and the system is especially suitable for mountain bikes.

[0132] Embodiment two:

[0133] Referring to the accompanying Figure 17 and the accompanying Figure 18 The mid-mounted variable speed system further comprises a first reversing gear set 41, the first reversing gear set 41 comprising 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 staggered inner tooth ring 411a and a connecting ring 411b, and the transmission frame 411 is fixed to the transmission shaft 4 through the connecting ring 411b; the plurality of reversing planetary gears 410 are installed on the shell 1 and are in engagement with the inner tooth ring 411a; the output cylinder 412 is rotatably installed on the transmission shaft 4, and one end of the output cylinder 412 is provided with an outer tooth part 412a for engagement with the reversing planetary gears 410, and the other end of the output cylinder 412 passes through the shell 1 and is provided with a second power output end 412b.

[0134] Specifically, when the mid-mounted variable speed system is applied to a bicycle, the second power output end 412b of the output cylinder 412 can be used to install a sprocket; 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 with the connecting ring 411b, so that the transmission shaft 4 is rotatable to drive the transmission frame 411 to transmit power, and since the plurality of reversing planetary gears 410 are installed on the shell 1 and the output cylinder 412 is rotatably sleeved on the transmission shaft 4, power is input through the transmission frame 411, transmitted by the plurality of reversing planetary gears 410, and finally output through the output cylinder 412, so that the rotation direction of the output cylinder 412 is opposite to that of the transmission shaft 4. Since the transmission shaft 4 and the first power shaft 2 are in gear external engagement, after the transmission of the first reversing gear set 41, the rotation direction of the output cylinder 412 is the same as that of the first power shaft 2, that is, in the embodiment, the rotation direction of the sprocket installed on the output cylinder 412 is the same as that of the first power shaft 2.

[0135] Embodiment three:

[0136] Referring to the accompanying Figure 19 - the accompanying Figure 21The middle transmission system further comprises a second reversing gear set 42, which comprises a transmission gear 421 and an output gear 420. The embodiment only describes the differences from the above embodiment. The third power output end 420a is arranged on the output gear 420, and specifically, the third power output end 420a is an axial extension structure of the output gear 420. The transmission gear 421 is coaxially fixed on the transmission shaft 4, and the output gear 420 is rotatably installed on the first power shaft 2 and engaged with the transmission gear 421. When the output gear 420 is assembled on the first power shaft 2, the third power output end 420a extends out of the shell 1 and is arranged. The third power output end 420a is used for connecting the toothed disc of the bicycle and the like to provide power for the wheel. In this embodiment, the output gear 420 can be assembled on the first power shaft 2 by a bearing mode, and a bearing is also arranged between the output gear 420 and the shell 1, so that the rotation of the output gear 420 and the first power shaft 2 does not interfere with each other. In order to ensure stable transmission of power, the transmission gear 421 is assembled on the transmission shaft 4 by a spline connection mode, 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 engaged with each other, so that the rotation direction of the third power output end 420a is opposite to that of the transmission shaft 4. Specifically, it can be compared with the first power output end 401 on the transmission shaft 4 in the first embodiment. The third power output end 420a is reversed due to the arrangement of the second reversing gear set 42. In summary, the power of this embodiment is provided by the power input end 201 fixed at both ends of the first power shaft 2, which drives 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. The transmission gear 421 and the output gear 420 are engaged and driven to realize reversing, and finally transmitted through the third power output end 420a fixed on the output gear 420.

[0137] Embodiment four:

[0138] This embodiment only describes the differences from the first embodiment. Refer to the description of the first embodiment. Figure 22The middle-mounted variable speed system comprises a second power shaft 22 and a support shaft 21 which is at least partially hollow and is rotatably installed in the housing 1 and is used for assembling the multi-stage driving wheel set 7 and the first gear shifting mechanism 3. In the embodiment, the support shaft 21 functions as the first power shaft 2 in the first embodiment, but the two ends of the support shaft 21 in the 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 which is used for connecting a pedal and providing power for the middle-mounted variable speed system. Correspondingly, an input gear 220 coaxially assembled on the second power shaft 22 is used for meshing with any stage of the multi-stage driving wheel set 7. When power is brought by the second power input end 221 to drive the second power shaft 22 to rotate, the input gear 220 meshes with any stage of the multi-stage driving wheel set 7 to reversely change the direction of rotation of the multi-stage driving wheel set 7. Since the multi-stage driving wheel set 7 also needs to mesh with the multi-stage driven wheel set 8 to transmit power, the direction of rotation is changed for the second time, and finally the direction of rotation of the first power output end 401 is the same as that of the second power input end 221. In the embodiment, the second power shaft 22 and the support shaft 21 are arranged on different shafts, the input gear 220 assembled on the second power shaft 22 meshes with the multi-stage driving wheel set 7 on the support shaft 21 to reversely change the direction of rotation, so that the direction of rotation of the first power output end 401 is the same as that of the second power input end 221, which is different from the direction of rotation of the first power output end 401 being opposite to that of the first power input end 301 in the first embodiment, so that the middle-mounted variable speed system can provide more varied directions of rotation.

[0139] To achieve one or part or all of the above purposes or other purposes, the utility model also proposes a bicycle, the bicycle includes above-mentioned middle-mounted variable speed system.

[0140] Obviously, the above-described embodiments are only some of the embodiments of the utility model, not all the embodiments, and the preferred embodiments of the utility model are given in the drawings, but do not limit the patent range of the utility model. The utility model can be realized in many different forms, and conversely, the purpose of providing these embodiments is to make the disclosure of the utility model more thorough and comprehensive. Although the utility model is described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing specific embodiments or make equivalent replacement to part of the technical features. Any equivalent structure made by using the contents of the utility model specification and drawings, directly or indirectly used in other related technical fields, is also within the patent protection range of the utility model.

Claims

1. A mid-mounted variable speed system characterized by, The application relates to a multi-speed transmission mechanism. The mechanism comprises a housing, a first power shaft, a first shift mechanism, a transmission shaft, 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 are rotatably connected to the housing, and the first power shaft has a first power input end extending out of the housing, and the transmission shaft has a first power output end extending out of the housing. The inner 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 with the multi-stage driving wheel set to form a first amplification wheel set. The multi-stage driving wheel set is rotatably arranged on the first power shaft. 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 amplification 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 limiting shaft extending into the first power shaft, and the second shift mechanism has a movable second limiting shaft extending into the transmission shaft; the first limiting shaft and the second limiting shaft each have a shift protrusion. The first shift mechanism can drive the first limiting shaft to make the shift protrusion abut against the first clutch transmission assembly to make the first power shaft and the sun gear in transmission connection, or drive the first limiting shaft to make the shift protrusion abut against the second clutch transmission assembly to make the first power shaft and the first amplification wheel set in transmission connection; the second shift mechanism can drive the second limiting shaft to make the shift protrusion abut against any third clutch transmission assembly to make the corresponding driven wheel and the transmission shaft in transmission connection.

2. The mid-mounted transmission system according to claim 1, characterized in that, The multi-stage driving wheel set comprises a second planetary gear set, a second driving wheel, a third driving wheel and an axial connection structure; and the multi-stage driven wheel set comprises a first driven wheel, a second driven wheel and a third driven wheel. The second planetary gear set comprises 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 the inner wall of the first driving wheel is provided with an inner tooth portion; the planet carrier is rotatably arranged on the first power shaft, and the plurality of second planetary gears are in mesh with the inner tooth portion of the first driving wheel to form a second amplification wheel set. A fourth clutch transmission assembly is arranged between the first power shaft and the planet carrier; the first shift mechanism can drive the first limiting shaft to make the shift protrusion abut against the fourth clutch transmission assembly to make the first power shaft and the planet carrier of the second planetary gear set in transmission connection. The second driving wheel is coaxially fixed on the connecting portion of the first driving wheel; The third driving wheel, the first driving wheel and the plurality of second planetary gears of the first planetary gear set are connected through the axial connection structure; the third driving wheel is connected with the first power shaft through the first clutch assembly; The first driving wheel is in mesh with the first driven wheel, the second driving wheel is in mesh with the second driven wheel, and the third driving wheel is in mesh 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 first ratchet structure, the first pawl is connected with an elastic sheet, and the first pawl is assembled into the mounting hole through the elastic sheet; the first ratchet structure is arranged on a sun gear of the first planetary gear set, a third driving wheel and an annular carrier of the second planetary gear set, the first pawl is compressed by the elastic sheet to be in a retracted state when not being abutted by a shift protrusion, and is not connected with the corresponding first ratchet structure; the first pawl is in an extended state when being abutted by the shift protrusion, and can be in transmission connection with the corresponding first ratchet structure, and a space is formed between the first pawl and the mounting hole for avoiding collision; The third clutch transmission assembly is composed of a second pawl and a second ratchet structure, the second pawl is connected with an elastic sheet, and the second pawl is assembled into the mounting hole through the elastic sheet, the second ratchet structure is arranged on each level of the multi-stage driven gear set, the second pawl is compressed by the elastic sheet to be in a retracted state when not being abutted by a shift protrusion, and is not connected with the corresponding second ratchet structure; the second pawl is in an extended state when being abutted by the shift protrusion, and can be in transmission connection with the corresponding second ratchet structure, and there is no space between the outer wall of the second pawl and the inner wall of the mounting hole for avoiding collision.

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; The first power shaft and the transmission shaft are both provided with axially extending threaded holes; The outer wall of the first limiting shaft and the second limiting shaft is both provided with external threads which are in threaded connection with the threaded holes; The first limiting shaft and the second limiting shaft are both provided with axially penetrating connecting holes which are connected with the rotating shaft of the control motor, and the screw rod can move along the axial direction of the rotating shaft of the control motor; The control module is electrically connected with 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 which are connected with the elastic sheets, and the first pawl and the second pawl are both provided with transition inclined walls which can be abutted by the shift protrusion when the shift protrusion moves axially.

6. The mid-mounted transmission system according to claim 2, characterized in that, The connecting part is an axial protrusion connected with the first driving wheel, and the outer wall of the axial protrusion is provided with splines.

7. The mid-mounted transmission system according to claim 3, characterized in that, The second planetary gear set further includes a cylindrical gear; When the plurality of planet gears of the second planetary gear set are assembled on the annular carrier, the second planet gears and the ratchet structure of the annular carrier are arranged axially offset from each other; The cylindrical gear is fixedly arranged on the housing, and the cylindrical gear is in meshing connection with the plurality of second planet gears of the second planetary gear set.

8. The mid-mounted transmission system according to claim 7, characterized in that The housing includes a left cover, a right cover and a middle shell with two open ends; One end of the first power shaft passes through the left cover and is connected with the left cover through a bearing, and the other end passes through the right cover and is connected with the right cover through a bearing; One end of the transmission shaft is connected with the left cover through a bearing, and the other end passes through the right cover and is connected with the right cover through a bearing; The left cover and the middle shell are sealingly connected at one end opening, and the right cover and the middle shell are sealingly connected at the other end opening.

9. The mid-variator system of claim 8, wherein, Further comprising a first reversing gear set, the first reversing gear set includes a plurality of reversing planet gears, a transmission carrier and an output cylinder; The transmission carrier is provided with an axially offset inner ring and a connecting ring, and the transmission carrier is fixed on the transmission shaft through the connecting ring; The first power shaft and the transmission shaft are both provided with axially extending threaded holes; A plurality of reversing planet wheels are mounted on the housing and engage with the inner tooth ring; The output cylinder is rotatably mounted on the transmission shaft, and one end of the output cylinder is provided with an outer tooth portion for engaging with the reversing planet wheel, 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 variable speed system characterized by, Comprise: A housing, a first power shaft which is at least partially hollow, a first gear shifting mechanism, a transmission shaft which is at least partially hollow, a second gear shifting mechanism, a first planetary gear set, a multi-stage driving wheel set, a multi-stage driven wheel set and a second reversing gear set; The first power shaft and the transmission shaft are both rotatably connected to the housing, and the first power shaft has a first power input end which extends out of the housing at both ends; The second reversing gear set comprises a transmission gear and an output gear, the transmission gear is coaxially fixed on the transmission shaft, and the output gear is rotatably mounted on the first power shaft and engages with the transmission gear; The output gear is provided with an axially extending power output end which extends out of the housing; The inner 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 planet wheels are fixedly connected with the multi-stage driving wheel set to form a first amplification wheel set; The multi-stage driving wheel set is rotatably arranged on the first power shaft; 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 amplification 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 gear shifting mechanism has a movable first limiting shaft which extends into the first power shaft, and the second gear shifting mechanism has a movable second limiting shaft which extends into the transmission shaft; the first limiting shaft and the second limiting shaft both have a gear shifting protrusion; The first gear shifting mechanism can drive the first limiting shaft to make the gear shifting protrusion abut against the first clutch transmission assembly to make the first power shaft and the sun gear in transmission connection, or drive the first limiting shaft to make the gear shifting protrusion abut against the second clutch transmission assembly to make the first power shaft and the first amplification wheel set in transmission connection; the second gear shifting mechanism can drive the second limiting shaft to make the gear shifting protrusion abut against any one of the third clutch transmission assemblies to make the corresponding driven wheel and the transmission shaft in transmission connection.

11. A mid-mounted variable speed system characterized by, Comprise: A housing, a first power shaft which is at least partially hollow, a first gear shifting mechanism, a transmission shaft which is at least partially hollow, a second gear shifting 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 which extends out of the housing at both ends, and the transmission shaft has a power output end which extends out of the housing at one end; the second power shaft has a coaxially assembled input gear; The inner 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 planet wheels are fixedly connected with the multi-stage driving wheel set to form a first amplification wheel set; The multi-stage driving wheel group is rotatably arranged on the support shaft; any stage of the multi-stage driving wheel group can be engaged with the input gear; The first clutch transmission assembly is arranged between the support shaft and the sun gear, and the second clutch transmission assembly is arranged between the support shaft and the first amplification wheel group; The multi-stage driven wheel group is rotatably arranged on the transmission shaft, and the third clutch transmission assembly is arranged between the transmission shaft and each stage of the multi-stage driven wheel group; The first shift mechanism has a movable first limiting shaft extending into the support shaft, and the second shift mechanism has a movable second limiting shaft extending into the transmission shaft; the first limiting shaft and the second limiting shaft each have a shift protrusion; The first shift mechanism can drive the first limiting shaft to make the shift protrusion abut against the first clutch transmission assembly to make the support shaft and the sun gear in transmission connection, or drive the first limiting shaft to make the shift protrusion abut against the second clutch transmission assembly to make the support shaft and the first amplification wheel group in transmission connection; the second shift mechanism can drive the second limiting shaft to make the shift protrusion abut against any one of the third clutch transmission assemblies to make the corresponding driven wheel and the transmission shaft in transmission connection.

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

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