CN219635418U - Three-stage speed changer of bicycle and bicycle - Google Patents

Abstract

The utility model discloses a three-stage transmission of a bicycle and the bicycle, which relate to the technical field of bicycles and comprise a speed regulator arranged on a handlebar and a speed changing sheet arranged on a bicycle body, wherein the speed regulator is connected with the speed changing sheet through a speed changing wire. The utility model drives the respective chains through the connection of the low-speed chain plate, the medium-speed chain plate and the high-speed chain plate respectively, the gear shifting plate controls the gear shifting, the gear shifting is stable and easy and has no dead angle by 360 degrees, the chain can not be shifted to take off the chain, the internal parts are realized through mechanical structures, no electronic device is involved, and the production and manufacturing cost is low.

Description

Three-stage speed changer of bicycle and bicycle

Technical Field

The utility model relates to the technical field of bicycles, in particular to a bicycle three-stage transmission and a bicycle.

Background

The bicycle finger-shifting speed regulator is used for shifting gears of a bicycle speed changer, and is connected to the bicycle speed changer through a control cable for shifting gears. In the current gear shifting process, the bicycle chain is matched with gear plates of different sizes, when the speed is regulated, the chain puller is pulled by a cable, the chain is pulled to the next flywheel from the current flywheel, and gear switching is completed, so that the transmission ratio of the front gear and the rear gear and the driving treading force are regulated, different use requirements are met, and the gear shifting mode has the following problems: 1. the chain is easy to be de-linked in the gear switching process, which causes inconvenience to users. 2. The gear shifting is more laborious, and the chain can be thoroughly shifted to the next flywheel by continuously using force on hands.

Disclosure of Invention

The utility model aims to provide a three-stage transmission of a bicycle and the bicycle, which are used for solving the problems in the background technology.

In order to achieve the above object, the present utility model provides the following technical solutions: the utility model provides a tertiary derailleur of bicycle, includes the speed regulator on locating the handlebar and the variable speed piece on the automobile body, the speed regulator passes through the variable speed line with the variable speed piece and is connected, including tertiary derailleur, tertiary derailleur includes shift dish, low-speed chain dish, medium-speed chain dish, high-speed chain dish and the crank of combining in proper order, low-speed chain dish and crank fixed connection, medium-speed chain dish, high-speed chain dish pass through the bearing with the crank and are connected, low-speed chain dish, medium-speed chain dish and high-speed chain dish are connected with the chain alone respectively, be equipped with the link gear on the crank, be equipped with the shift mechanism on the shift dish, through the shift mechanism on the shift dish with interact between the link gear on the crank and control medium-speed chain dish, high-speed chain dish, the shift dish is connected with the variable speed piece contact.

Further preferably, the linkage mechanism comprises a crank arm, a rotating shaft, a medium-speed chain disk control key and a high-speed chain disk control key, wherein the crank arm is fixedly connected with the rotating shaft, the high-speed chain disk control key is connected to the end part of the crank arm through a limiting assembly, a sliding groove is formed in the side wall of the rotating shaft, and the medium-speed chain disk control key is connected in the sliding groove of the side wall of the rotating shaft through a second spring.

Preferably, the limiting component comprises a fixed frame and a fixed cover plate, the middle part of the fixed frame is a square through hole, a screw hole is formed in the end part of the fixed frame, a corresponding through hole is formed in the side end of the fixed cover plate, a round through hole is formed in the position, corresponding to the square through hole in the middle part of the fixed frame, of the end face of the rotating shaft, the high-speed chain disc control key is a square block, one end of the high-speed chain disc control key is provided with a bulge, the other end of the same side is provided with a round column, the end face of the bulge is an inclined face, one end, opposite to the round column, of the high-speed chain disc control key is provided with a round hole, a third spring is arranged in the round hole, the medium-speed chain disc control key is an L-shaped plate, a round hole is formed in one end part of the medium-speed chain disc control key, a second spring is arranged in the round hole, the end face of the other side of the L-shaped chain disc control key is movably connected to the square through the third spring in the square through hole in the middle part of the fixed frame, and the round column at the end of the high-speed chain disc control key penetrates through the round hole in the rotating shaft.

Preferably, the gear shifting mechanism comprises a first rotary table and a second rotary table, and the second rotary table is rotationally connected with the first rotary table;

the first turntable is provided with a medium speed guide groove and a high speed guide groove, a V-shaped limiting block is arranged in the medium speed guide groove and the high speed guide groove and connected in the groove through a pin, the V-shaped limiting block can rotate in the groove, the bottom of the pin is connected with a reset spring for limiting the rotation of the V-shaped limiting block, at least one side edge of the medium speed guide groove and at least one side edge of the high speed guide groove are connected with a return tension spring, the other end of the return tension spring is connected to the second turntable, and the first turntable is provided with a medium speed small bearing and a high speed small bearing;

be equipped with intermediate speed bull stick and high-speed bull stick on the second carousel, intermediate speed bull stick and high-speed bull stick one end rotate connect on the second carousel, and the other end is equipped with branch, branch stretches into intermediate speed guide way and high-speed guide way and can slide in the groove, intermediate speed bull stick, high-speed bull stick middle part are connected with spacing spring and make it lean on all the time to second carousel centre of a circle direction, first groove and the second groove of stepping down have been seted up at second carousel middle part, first groove department of stepping down is equipped with adjusting part.

Preferably, the adjusting component comprises an adjusting rod, a connecting plate and a pulling plate, the middle part of the adjusting rod is rotationally connected with the connecting plate, the end part of the adjusting rod is fixedly connected with the pulling plate, the connecting plate is fixed on the second turntable, and the pulling plate is connected with the second turntable through a spring.

Preferably, the low-speed chain plate is connected with a medium-speed pressure changing part and a high-speed pressure changing part through a movable shaft, the medium-speed pressure changing part is provided with a pressing rod, the pressing rod can be pressed into a groove of a control key of the medium-speed chain plate along with the rotation of the medium-speed pressure changing part, and the high-speed pressure changing part is contacted with an adjusting rod of the adjusting component.

Preferably, the middle parts of the medium-speed chain disk and the high-speed chain disk are provided with coaxial ring shafts, and the end faces of the ring shafts are provided with helical teeth.

Preferably, the width of the medium speed chain plate control key is the same as the width of the high speed chain plate control key.

Preferably, washers are respectively arranged among the gear shifting disc, the low-speed chain disc, the medium-speed chain disc and the high-speed chain disc.

Another object of the present utility model is to provide a bicycle that includes the three-speed bicycle transmission described above.

In the technical scheme, the utility model has the technical effects and advantages that:

1. the utility model drives the respective chains through the connection of the low-speed chain plate, the medium-speed chain plate and the high-speed chain plate respectively, the gear shifting plate controls the gear shifting, the gear shifting is stable and easy and has no dead angle by 360 degrees, the chain can not be shifted to take off the chain, the internal parts are realized through mechanical structures, no electronic device is involved, and the production and manufacturing cost is low.

2. The utility model can respectively control different chain discs to achieve different speed matching effects through ingenious structural design, has quick and flexible speed change, less faults, no time difference and long service life.

Drawings

In order to more clearly illustrate the embodiments of the present utility model or the technical solutions in the prior art, the drawings required for the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments described in the present utility model, and other drawings may be obtained according to these drawings for a person having ordinary skill in the art.

FIG. 1 is a schematic view of the structure of a shift disk of the present utility model;

FIG. 2 is a schematic view of a first rotor structure according to the present utility model;

FIG. 3 is a schematic diagram of a second turntable according to the present utility model;

FIG. 4 is a schematic view of the structure of the adjusting assembly of the present utility model;

FIG. 5 is a schematic diagram of a crank linkage mechanism according to the present utility model;

FIG. 6 is an exploded view of the crank linkage of the present utility model;

FIG. 7 is a schematic view of a low speed chain plate according to the present utility model;

FIG. 8 is a schematic diagram of a medium speed chain plate structure according to the present utility model;

FIG. 9 is a schematic view of a high speed chain plate structure according to the present utility model;

FIG. 10 is a schematic view of the structure of the circular shaft of the medium speed chain plate and the high speed chain plate according to the present utility model.

Reference numerals illustrate:

1-a gear shifting disc; 2-a limiting assembly; 3-bulge; 4-circular columns; 5-grooves; 6-a second spring; 7-a third spring; 8-a first turntable; 9-a first turn plate; 12-a low speed chain plate; 13-medium speed chain plate; 14-high speed chain plate; 15-and crank; 16-a circular shaft; 1501-crank arm; 1502-a rotating shaft; 1503-medium speed chain disk control; 1504-high speed chain disk control keys; 201-a fixed frame; 202-fixing a cover plate; 801-a medium speed guide groove; an 802-V type limiting block; 803-pins; 804-a return tension spring; 805—a medium speed small bearing; 806-high speed small bearings; 807-high speed guide slots; 901-a medium-speed rotating rod; 902-a strut; 903—a limit spring; 904—a first yield slot; 905-a second yield slot; 906-high speed rotating rod 100-adjustment assembly; 1001-adjusting the rod; 1002-connecting plates; 1003-pulling plate; 1201—medium speed press-change member; 1202-a compression bar; 1203—high speed press-change.

Detailed Description

In order to make the technical scheme of the present utility model better understood by those skilled in the art, the present utility model will be further described in detail with reference to the accompanying drawings.

As shown in fig. 1-10, a bicycle three-stage transmission comprises a speed regulator arranged on a handlebar and a speed changing sheet arranged on a bicycle body, wherein the speed regulator is connected with the speed changing sheet through a speed changing wire, the bicycle three-stage transmission comprises a gear shifting disc 1, a low-speed chain disc 12, a medium-speed chain disc 13, a high-speed chain disc 14 and a crank 15 which are sequentially combined, the low-speed chain disc 12 is fixedly connected with the crank 15, the medium-speed chain disc 13, the high-speed chain disc 14 and the crank 15 are connected through bearings, the low-speed chain disc 12, the medium-speed chain disc 13 and the high-speed chain disc 14 are respectively and independently connected with a chain, a linkage mechanism is arranged on the crank 15, a gear shifting mechanism is arranged on the gear shifting disc 1, the medium-speed chain disc 13 and the high-speed chain disc 14 are controlled through interaction between the gear shifting mechanism on the gear shifting disc 1 and the linkage mechanism on the crank 15, and the gear shifting sheet is in contact connection.

The speed regulator on the handle is twisted to enable the variable sheet and the gear shifting disc 1 to generate friction force, the outer ring of the gear shifting disc 1 is limited to rotate, the gear shifting mechanism acts, the control keys of the internal parts of the gear shifting disc 1 generate displacement, the medium speed chain disc 13 is controlled, and the vehicle advances at medium speed; when the high speed is needed, the speed regulator is twisted, the speed changing sheet and the gear shifting disc 1 generate friction, the gear shifting disc 1 controls the high-speed chain disc 14, and the vehicle advances at high speed; when the gear is required to be shifted down, the speed regulator is twisted, the vehicle returns to the low-speed gear position, each chain plate is independently connected with a respective chain, the condition of shifting the chain does not exist, 360 degrees of gear shifting of the circular gear shifting plate 1 do not exist, the gear shifting is rapid, flexible and less in faults, no time difference exists, the service life is long, the distance between the gear shifting plate and the gear shifting plate 1 is 10mm when the gear shifting plate is not in work, and normal work cannot be influenced.

Further preferably, as shown in fig. 5 and 6, the linkage mechanism comprises a crank arm 1501, a rotating shaft 1502, a middle speed chain disk control key 1503 and a high speed chain disk control key 1504, wherein the crank arm 1501 is fixedly connected with the rotating shaft 1502, the high speed chain disk control key 1504 is connected to the end part of the crank arm 1501 through a limiting component 2, a chute is formed in the side wall of the rotating shaft 1502, and the middle speed chain disk control key 1503 is connected in the chute in the side wall of the rotating shaft 1502 through a second spring 6.

Preferably, the limiting component 2 comprises a fixed frame 201 and a fixed cover plate 202, the middle part of the fixed frame 201 is a square through hole, a screw hole is formed in the end part of the fixed frame 201, a corresponding through hole is formed in the side end of the fixed cover plate 202, a round through hole is formed in the end face of the rotating shaft 1502 and corresponds to the square through hole in the middle part of the fixed frame 201, the high-speed chain disc control key 1504 is a square block, a bulge 3 is arranged at one end of the high-speed chain disc control key 1504, a round hole is formed in the other end of the same side, the end face of the bulge 3 is an inclined face, a round hole is formed in the end face, opposite to the round column 4, of the high-speed chain disc control key 1504, a third spring 7 is arranged in the round hole, the medium-speed chain disc control key 1503 is an L-shaped plate, a round hole is formed in one end part of the medium-speed chain disc control key 1503, a second spring 6 is arranged in the round hole, a groove 5 is formed in the end face of the other side of the L-shaped medium-speed chain disc control key 1504, the high-speed chain disc control key 1504 is movably connected in the square through the round through hole in the middle part of the fixed frame 201, and the round column 4 at the end of the high-speed chain disc control key 1504 penetrates through the round hole in the rotating shaft 1502.

The middle speed chain disk control key 1503 controls the middle speed chain disk 13, is connected in a chute on the side wall of the rotating shaft 1502 through a second spring 6, when the gear is shifted to the middle speed, the middle speed chain disk control key 1503 is stressed to generate displacement, and moves and clamps into the helical teeth of the circular shaft 16 of the middle speed chain disk 13, and the crank 15 rotates to drive the middle speed chain disk 13 to rotate so as to operate at the middle speed; the high-speed chain disk control key 1504 controls the high-speed chain disk 14, the high-speed chain disk control key 1504 is a square block, one end of the high-speed chain disk control key 1504 is provided with a bulge 3, the other end of the same side is provided with a circular column 4, the end face of the bulge 3 is an inclined plane, the circular column 4 penetrates through the rotating shaft 1502 and stretches out, when the high-speed chain disk control key 1504 is shifted to a high-speed gear, the bulge 3 below the high-speed chain disk control key 1504 is clamped into the helical teeth of the circular shaft 16 of the high-speed chain disk 14 under the action of the third spring 7, and the crank 15 rotates to drive the high-speed chain disk 14 to rotate so as to run at a high speed.

Preferably, as shown in fig. 1-3, the gear shifting mechanism comprises a first rotary disc 8 and a second rotary disc 9, and the second rotary disc 9 is rotatably connected with the first rotary disc 8;

the first turntable 8 is provided with a medium speed guide groove 801 and a high speed guide groove 807, a V-shaped limiting block 802 is arranged in the medium speed guide groove 801 and the high speed guide groove 807, the V-shaped limiting block 802 is connected in the groove through a pin 803, the V-shaped limiting block 802 can rotate in the groove, the bottom of the pin 803 is connected with a return spring for limiting the rotation of the V-shaped limiting block 802, at least one side edge of the medium speed guide groove 801 and the high speed guide groove 807 is connected with a return tension spring 804, the other end of the return tension spring 804 is connected to the second turntable 9, and the first turntable 8 is provided with a medium speed small bearing 805 and a high speed small bearing 806;

the second carousel 9 is last to be equipped with intermediate speed bull stick 901 and high-speed bull stick 906, intermediate speed bull stick 901 and high-speed bull stick 906 one end rotate connect on the second carousel 9, the other end is equipped with branch 902, branch 902 stretches into intermediate speed guide slot 801 and high-speed guide slot 807 and can slide in the groove, intermediate speed bull stick 901, high-speed bull stick 906 middle part is connected with spacing spring 903 makes it lean on all the time to the direction of the centre of a circle of second carousel 9, first groove 904 and the second groove 905 of stepping down have been seted up at the second carousel 9 middle part, first groove 904 department of stepping down is equipped with adjusting part 100.

The second turntable 9 rotates to drive the medium speed rotating rod 901, the high speed rotating rod 906 and the supporting rod 902 to move along the medium speed guide groove 801 and the high speed guide groove 807, the medium speed rotating rod 901 and the high speed rotating rod 906 always lean against the center direction of the turntable under the action force of the limiting spring 903, the supporting rod 902 moves in the groove to be limited at the V-shaped limiting block 802, the V-shaped limiting block 802 is clamped in the concave cavity of the V-shaped limiting block 802, the V-shaped limiting block 802 also bounces back to the initial position under the limitation of the reset spring at the bottom of the pin 803, and the reset tension spring 804 drives the second turntable 9 to return to the initial position.

Preferably, as shown in fig. 4, the adjusting assembly 100 comprises an adjusting rod 1001, a connecting plate 1002 and a pull plate 1003, wherein the middle part of the adjusting rod 1001 is rotationally connected with the connecting plate 1002, the end part of the adjusting rod 1001 is fixedly connected with the pull plate 1003, the connecting plate 1002 is fixed on the second rotary table 9, and the pull plate 1003 is connected with the second rotary table 9 through a spring. The adjusting assembly 100 is used for controlling the high-speed chain disc control key 1504, the adjusting lever 1001 contacts with the circular column 4 of the high-speed chain disc control key 1504, the adjusting lever 1001 is tilted to eject the circular column 4, and the protrusion 3 below the high-speed chain disc control key 1504 is separated from the helical tooth of the circular shaft 16 of the high-speed chain disc 14.

Preferably, as shown in fig. 7, the low-speed chain wheel 12 is connected with a medium-speed pressure changing member 1201 and a high-speed pressure changing member 1203 through a movable shaft, a pressing rod 1202 is arranged on the medium-speed pressure changing member 1201, the pressing rod 1202 can be pressed into a groove 5 of the medium-speed chain wheel control key 1503 along with the rotation of the medium-speed pressure changing member 1201, and the high-speed pressure changing member 1203 is in contact with the adjusting rod 1001 of the adjusting assembly 100. When shifting the gear, the small medium-speed bearing 805 on the gear shifting disc 1 presses the medium-speed pressure changing piece 1201, and the pressing rod 1202 presses the groove 5 of the medium-speed chain disc control key 1503 along with the pressure received by the medium-speed pressure changing piece 1201, so as to control the medium-speed chain disc control key 1503 to push inwards to be engaged with the helical teeth of the circular ring shaft 16; the small high-speed bearing 806 on the gear-shifting variable disc 1 presses on the high-speed pressing variable piece 1203, the high-speed pressing variable piece 1203 presses one end of the adjusting rod 1001, the other end of the adjusting rod 1001 gives way to the round column 4 of the high-speed chain disc control key 1504, and the lower bulge 3 of the high-speed chain disc control key 1504 is matched with the helical teeth of the round shaft 16 of the high-speed chain disc 14 under the acting force of the third spring 7.

Preferably, as shown in fig. 8, 9 and 10, the middle part of the middle speed chain disk 13 and the middle part of the high speed chain disk 14 are provided with coaxial ring shafts 16, and the end surfaces of the ring shafts 16 are provided with helical teeth. And (3) tooth unreeling, so that the control key can be separated at any time and can be closed under the action of the spring.

Preferably, the medium speed chain wheel control 1503 and the high speed chain wheel control 1504 have the same width.

Preferably, washers are provided between the shift plate 1, the low speed chain plate 12, the medium speed chain plate 13, and the high speed chain plate 14, respectively.

Another object of the present utility model is to provide a bicycle that includes the three-speed bicycle transmission described above.

Working process and principle:

the low, medium and high speed chain discs are installed, a crank 15 is fixedly connected with the low speed chain disc 12 and the second rotary disc 9, the crank 15 is connected with the medium and high speed chain discs through bearings, and the first rotary disc 8 and the second rotary disc 9 are rotationally connected to form an integral gear shifting disc 1; starting to a low gear without control of the gear shifting disc 1, except for a middle speed chain disc and a high speed chain disc, other parts rotate along with a crank 15, the middle speed chain disc 13 and the high speed chain disc 14 are still in a static state, when the gear shifting is performed, a speed regulator on a handle is twisted, a speed changing sheet is in friction contact with the outer ring of the gear shifting disc 1, namely the first rotary disc 8 is limited to rotate, the first rotary disc 8 and the second rotary disc 9 generate relative rotation, a middle speed rotary rod 901 of the second rotary disc 9 moves along a middle speed guide groove 801 and moves to a concave cavity of a V-shaped limiting block 802 to be limited, at the moment, a middle speed small bearing 805 of the first rotary disc 8 is just pressed on a middle speed pressure changing part 1201 of the low speed chain disc 12, so that a pressing rod 1202 on the middle speed pressure changing part 1201 is pressed into a groove 5 of a middle speed chain disc control key 1503, the middle speed chain disc control key 1503 is meshed with a bevel of a circular shaft 16 of the middle speed chain disc 13, at the moment, the low speed chain disc 12 and the middle speed chain disc 13 synchronously rotate, and the high speed chain disc 14 is in a static state.

When the gear is shifted, the speed regulator on the handle is twisted again, the speed changing sheet is in friction contact with the outer ring of the gear shifting disc 1, the second rotary disc 9 and the first rotary disc 8 generate relative rotation, the high-speed rotary rod 906 of the second rotary disc 9 moves along the high-speed guide groove 807 and moves into the concave cavity of the V-shaped limiting block 802 to be limited, at the moment, the high-speed small bearing 806 of the first rotary disc 8 presses the high-speed pressing variable part 1203 of the low-speed chain disc 12, the high-speed pressing variable part 1203 presses one end of the adjusting rod 1001, which is close to a spring, so that the other end of the adjusting rod 1001 is rotated into the first yielding groove 904 of the second rotary disc 9, and the high-speed chain disc control key 1504 is engaged with the helical teeth of the annular shaft 16 of the high-speed chain disc 14 under the action of the third spring 7, and at the moment, the low-speed chain disc 12 and the medium-speed chain disc 13 are in idle.

The speed regulator on the handle is turned to be in friction contact with the outer ring of the gear shifting disc 1 from high speed to low speed, the high-speed rotating rod 906 is separated from the V-shaped limiting block 802, the return tension spring 804 pulls the first rotary disc 8 back to the initial position, the high-speed small bearing 806 is separated from the high-speed pressing variable part 1203, meanwhile, the medium-speed small bearing 805 is also separated from the medium-speed pressing variable part 1201, the crank 15 stops rotating for one second, the helical teeth of the annular shaft 16 of the high-speed chain disc 14 are separated from the high-speed chain disc control key 1504, the helical teeth of the annular shaft 16 of the medium-speed chain disc 13 are also separated from the medium-speed chain disc control key 1503, and the vehicle runs at a low speed.

The oblique direction of the helical teeth of the annular shaft 16 can be adjusted as required; in order to protect the whole device, a protecting shell can be added outside the protecting device, and the middle speed chain plate 13 and the high speed chain plate 14 can be separately and independently arranged with the gear shifting plate 1 and the low speed chain plate 12.

In summary, the low-speed chain plate 12, the medium-speed chain plate 13 and the high-speed chain plate 14 are respectively connected to drive respective chains, the shift plate 1 is used for controlling the shift to switch gears, the shift is smooth and easy, 360-degree dead angle free is realized, the condition that the chains are not shifted to take off chains is avoided, the internal parts are realized through mechanical structures, no electronic devices are involved, the production and manufacturing cost is low, and the related parts of the existing bicycle can be integrally replaced.

While certain exemplary embodiments of the present utility model have been described above by way of illustration only, it will be apparent to those of ordinary skill in the art that modifications may be made to the described embodiments in various different ways without departing from the spirit and scope of the utility model. Accordingly, the drawings and description are to be regarded as illustrative in nature and not as restrictive of the scope of the utility model, which is defined by the appended claims.

Claims (10)

1. The utility model provides a tertiary derailleur of bicycle, includes the speed regulator and the speed change piece on the automobile body of locating on the handlebar, the speed regulator passes through the variable speed line with the speed change piece and is connected, its characterized in that: including tertiary derailleur, tertiary derailleur includes shift dish (1), low-speed chain dish (12), medium-speed chain dish (13), high-speed chain dish (14) and crank (15) of combining in proper order, low-speed chain dish (12) and crank (15) fixed connection, medium-speed chain dish (13), high-speed chain dish (14) are connected through the bearing with crank (15), low-speed chain dish (12), medium-speed chain dish (13) and high-speed chain dish (14) are connected with the chain alone respectively, be equipped with link gear on crank (15), be equipped with shift mechanism on shift dish (1), through shift mechanism on shift dish (1) with interact between the link gear on crank (15) and control medium-speed chain dish (13), high-speed chain dish (14), shift dish (1) are connected with the speed change piece contact.

2. A bicycle three-speed transmission according to claim 1, wherein: the linkage mechanism comprises a crank arm (1501), a rotating shaft (1502), a medium-speed chain disc control key (1503) and a high-speed chain disc control key (1504), wherein the crank arm (1501) is fixedly connected with the rotating shaft (1502), the high-speed chain disc control key (1504) is connected to the end part of the crank arm (1501) through a limiting assembly (2), a sliding groove is formed in the side wall of the rotating shaft (1502), and the medium-speed chain disc control key (1503) is connected into the sliding groove in the side wall of the rotating shaft (1502) through a second spring (6).

3. A bicycle three-speed transmission according to claim 2, characterized in that: spacing subassembly (2) are including fixed frame (201) and fixed apron (202), fixed frame (201) middle part is a square through-hole, the screw has been seted up to fixed frame (201) tip, corresponding through-hole has been seted up to fixed apron (202) side, round through-hole has been seted up with the square through-hole department in fixed frame (201) middle part corresponding position on pivot (1502) terminal surface, high-speed chain dish control key (1504) are a square piece, and its one end is equipped with arch (3), and the homonymy other end is equipped with round post (4), the terminal surface of arch (3) is the inclined plane, round hole has been seted up with round post (4) relative one end on high-speed chain dish control key (1504), be equipped with third spring (7) in the round hole, round hole has been seted up to medium-speed chain dish control key (1503), be equipped with second spring (6) in the round hole, the terminal surface on the other limit of L shape is equipped with recess (5), high-speed chain dish control key (1504) are through third spring (7) swing joint in the through-hole (1502) in the pivot of fixed frame (201) terminal part on the round through-hole (4).

4. A bicycle three-speed transmission according to claim 3, wherein: the gear shifting mechanism comprises a first rotary table (8) and a second rotary table (9), and the second rotary table (9) is rotationally connected with the first rotary table (8);

the novel rotary table is characterized in that a medium speed guide groove (801) and a high speed guide groove (807) are formed in the first rotary table (8), a V-shaped limiting block (802) is arranged in the medium speed guide groove (801) and the high speed guide groove (807), the V-shaped limiting block (802) is connected in the groove through a pin (803), the V-shaped limiting block (802) can rotate in the groove, a reset spring is connected to the bottom of the pin (803) and used for limiting rotation of the V-shaped limiting block (802), a reset tension spring (804) is connected to at least one side edge of the medium speed guide groove (801) and at least one side edge of the high speed guide groove (807), the other end of the reset tension spring (804) is connected to the second rotary table (9), and a medium speed small bearing (805) and a high speed small bearing (806) are arranged on the first rotary table (8);

be equipped with intermediate speed bull stick (901) and high-speed bull stick (906) on second carousel (9), intermediate speed bull stick (901) and high-speed bull stick (906) one end rotate connect on second carousel (9), and the other end is equipped with branch (902), branch (902) stretch into intermediate speed guide way (801) and high-speed guide way (807) and can slide in the groove, intermediate speed bull stick (901), high-speed bull stick (906) middle part are connected with spacing spring (903) make it lean on all the time to second carousel (9) centre of a circle direction, first groove (904) and second groove (905) of stepping down are seted up at second carousel (9) middle part, first groove (904) department of stepping down is equipped with adjusting part (100).

5. A bicycle three speed transmission according to claim 4, wherein: the adjusting assembly (100) comprises an adjusting rod (1001), a connecting plate (1002) and a pulling plate (1003), the middle of the adjusting rod (1001) is rotationally connected with the connecting plate (1002), the end of the adjusting rod (1001) is fixedly connected with the pulling plate (1003), the connecting plate (1002) is fixed on the second rotating disc (9), and the pulling plate (1003) is connected with the second rotating disc (9) through a spring.

6. A bicycle three speed transmission according to claim 5, wherein: the low-speed chain plate (12) is connected with a medium-speed pressure changing part (1201) and a high-speed pressure changing part (1203) through a movable shaft, the medium-speed pressure changing part (1201) is provided with a pressing rod (1202), the pressing rod (1202) can be pressed into a groove (5) of a medium-speed chain plate control key (1503) along with the rotation of the medium-speed pressure changing part (1201), and the high-speed pressure changing part (1203) is in contact with an adjusting rod (1001) of an adjusting assembly (100).

7. A bicycle three-speed transmission according to claim 1, wherein: the middle parts of the medium-speed chain disk (13) and the high-speed chain disk (14) are provided with coaxial ring shafts (16), and the end surfaces of the ring shafts (16) are provided with helical teeth.

8. A bicycle three-speed transmission according to claim 2, characterized in that: the medium speed chain disk control key (1503) and the high speed chain disk control key (1504) have the same width.

9. A bicycle three speed transmission according to any one of claims 1-8, wherein: washers are respectively arranged among the gear shifting disc (1), the low-speed chain disc (12), the medium-speed chain disc (13) and the high-speed chain disc (14).

10. A bicycle, characterized in that: a three-speed transmission for a bicycle comprising the device according to any one of claims 1 to 9.