CN219492960U - Compact bicycle middle shaft gearbox with load speed change - Google Patents

Abstract

The utility model relates to a bicycle speed changer in a vehicle, in particular to a compact bicycle middle shaft speed changer with load speed change, which comprises a box-type speed changer and a gear shifting device, wherein one of main shaft gears is a direct drive gear, and an output chain wheel is fixed on the direct drive gear; at least one of the driving ratchet wheel and the driven ratchet wheel is a double-ratchet wheel, two main shaft gears or two auxiliary shaft gears with single ratchet teeth are arranged on two sides of the double-ratchet wheel, and the double-ratchet wheel moves left and right on the main shaft or the auxiliary shaft and is respectively meshed with/separated from the two main shaft gears or the two auxiliary shaft gears of the single ratchet teeth through the ratchet teeth on two sides; the connecting piece of gear shifting driving lever and the shift fork is an elastic connecting piece, and the compact bicycle speed changer adopting the technical scheme has compact structure, can directly advance gear and withdraw gear, and has stable operation.

Description

Compact bicycle middle shaft gearbox with load speed change

Technical Field

The utility model relates to a bicycle speed changer in a vehicle, in particular to a compact bicycle bottom bracket bearing speed changer with load speed change.

Background

Bicycles, also known as bicycles or scooters. At present, the transmission speed ratio of the bicycle is fixed and unchanged and the speed ratio is adjustable, most of the bicycles adopt flywheel fluted discs with different teeth numbers which are fixedly arranged on the flywheel, different transmission speed ratios are realized by combining a chain adjusting sprocket with the flywheel fluted discs with different teeth numbers, the mode structure for changing the transmission speed ratio is simple, but the speed ratio adjusting range of the bicycle is narrower, the gear shifting is difficult, and a compact speed changer with small volume is needed to be adopted on the speed-changing bicycle.

The existing speed-changing bicycle speed changer usually adopts a structure with a plurality of chain discs, and the position of a chain is adjusted to enable the speed-changing bicycle speed changer to be connected with different chain discs in a matched mode, so that the mode of shifting gears is relatively troublesome, the situation that the shifting gears fail often occurs when the bicycle runs, and the abrasion to the chain is relatively large; there are also individual speed-changing bicycle transmissions using a gear box, for example, chinese patent CN205168799U discloses a central axle type bicycle internal transmission which is formed by arranging a first groove between two second transmission gears of each planetary gear set, and arranging a first protrusion capable of being inserted into the first groove on an inner circumferential surface of a gear ring, so that six gear rings can be fixed on a planetary gear fixing frame. Most of the prior transmissions use common gears for rotation, and some of the prior transmissions use planetary gears for transmission, and the prior transmissions generally have a plurality of meshes. Because the structure of the speed changer is complex, the parts are more, and the parts need to be precisely matched, so that the size of the speed changer is difficult to reduce. Meanwhile, when the transmission shifts gears, the transmission needs to enter a neutral gear first and then shifts gears, and the operation is complex. In addition, the gear has certain potential safety hazards in the neutral gear, and partial safety accidents occur due to entering the neutral gear.

Engagement is an important component of a transmission, and the existing engagement structure is complex: a ring is arranged beside the transmission gear of each gear, a conical surface for friction is arranged on the gear, a meshing sleeve is arranged between the two rings, and structures such as sliding blocks, spring rings and the like are required to be arranged between the meshing sleeve and the rings. During gear shifting, a neutral gear is firstly entered, and then a gear is entered; when the gear is shifted, the ring and the transmission gear can be meshed with the ring and the transmission gear only after the friction force acts on the ring and the transmission gear, and then gear shifting is completed. CN203098620U announces an automobile gearbox, comprising a gear hub, a ring, a meshing sleeve and a sliding block for enabling the meshing sleeve to push the ring to slide during gear shifting, wherein the ring is provided with a groove matched with the sliding block, the sliding block is positioned in the groove during neutral gear, an elastomer is attached to the side surface of the sliding block, and the end surface of the elastomer is contacted with the groove surface of the groove. According to the automobile gearbox provided by the utility model, the sliding block is in non-rigid contact with the ring during gear shifting, so that gear shifting noise can be reduced, and continuous friction between the ring and the gear can be avoided during gear shifting.

The prior compact bicycle speed changer has the defects of not compact gear shifting structure and incapability of better direct gear shifting and gear reversing.

Disclosure of Invention

The utility model aims to provide a compact bicycle bottom bracket bearing gearbox with load speed change, which has compact structure, can directly advance and withdraw gears, has stable operation, and overcomes the defects of the prior compact bicycle gearbox that the gear change structure is not compact and the advance and the withdrawal gears cannot be better.

In order to achieve the aim, the utility model provides a compact bicycle middle shaft gearbox with load speed change, which comprises a box type gearbox and a gear shifting device, wherein the box type gearbox comprises a box body, a main shaft, a countershaft and an output sprocket, a plurality of main shaft gears and a driving ratchet wheel are arranged on the main shaft, a plurality of countershaft gears and driven ratchet wheels are arranged on the countershaft, a shifting groove is arranged between the driving ratchet wheel and the driven ratchet wheel, and the main shaft gears and the countershaft gears are mutually matched and meshed; the gear shifting device comprises a gear shifting drum, a gear shifting rod and a gear shifting fork, wherein the gear shifting drum is rotationally fixed on a box body, two ends of a main shaft and a secondary shaft are installed on the box body through bearings, the gear shifting rod can move left and right and is movably fixed on the box body, a gear shifting drum groove is formed in the circumferential surface of the gear shifting drum, the gear shifting fork comprises a lower-section fork part and an upper-section fork connecting part, the fork part is clamped in the middle of a ratchet wheel and is in a shifting groove, the front end of the gear shifting rod is movably fixed in the gear shifting drum groove, the rear end of the gear shifting rod is movably connected with the shifting fork connecting part, one of main shaft gears is a direct-drive gear, and an output sprocket is fixed on the direct-drive gear; at least one of the driving ratchet wheel and the driven ratchet wheel is a double-ratchet wheel, two main shaft gears or two auxiliary shaft gears with single ratchet teeth are arranged on two sides of the double-ratchet wheel, and the double-ratchet wheel moves left and right on the main shaft or the auxiliary shaft and is respectively meshed with/separated from the two main shaft gears or the two auxiliary shaft gears of the single ratchet teeth through ratchet teeth on two sides; the connecting piece of gear shifting driving lever and shift fork is elastic connecting piece.

By adopting the technical scheme, because one of the main shaft gears is the direct-drive gear, the output chain wheel is fixed on the direct-drive gear, compared with the existing compact transmission, the gear pair is reduced, so that the gear shifting structure is more compact, meanwhile, the gear shifting deflector rod and the connecting piece of the shifting fork are elastic connecting pieces, and when the gear is shifted in or out, the rigid contact between ratchets corresponding to ratchets of the main shaft gears or the auxiliary shaft gears is avoided when the ratchets are combined, so that the phenomenon of tooth hitting and clamping stagnation does not occur, the gear can be better directly shifted in and out, and meanwhile, the defect that the existing compact transmission is easy to jump in the case of bad riding road conditions can be also ensured by the mature gear shifting drum technology.

Furthermore, the limiting elastic connecting piece adopts a simple and practical metal spring piece, the upper end of the metal spring piece is fixedly connected to the gear shifting rod, and the lower end of the metal spring piece movably clamps the gear shifting fork.

The same reason limits that the elastic connecting piece is a torsion spring, the torsion spring comprises a torsion spring body and a torsion spring output end, the torsion spring body is fixedly connected to the gear shifting deflector rod, and the gear shifting deflector is movably clamped by the torsion spring output end.

Further, other specific structures except for the gear shifting drum in the gear shifting device are specifically limited, namely the gear shifting device further comprises a fixing plate and a shifting fork guide rod, wherein the fixing plate is fixed on the box body, the shifting fork guide rod is fixed on the fixing plate or directly fixed on the box body, the shifting fork connecting part is a hollow tube, and the hollow tube is movably sleeved on the shifting fork guide rod.

Still further, the five-gear transmission adopting the technical proposal is limited, the main shaft is provided with a first-gear main shaft gear, a five-gear main shaft gear, a three-gear main shaft gear, a four-gear main shaft gear and a direct drive gear from left to right, a first double-ratchet wheel is arranged between the five-gear main shaft gear and the three-gear main shaft gear, a second double-ratchet wheel is arranged between the four-gear main shaft gear and the direct drive gear, wherein the first-gear main shaft gear is fixedly connected to the main shaft, the five-gear main shaft gear, the three-gear main shaft gear, the four-gear main shaft gear and the direct drive gear are sleeved on the main shaft in an empty mode, and the first double-ratchet wheel and the second double-ratchet wheel are sleeved on the main shaft in a sliding mode; the auxiliary shaft is provided with a first-gear auxiliary shaft gear, a five-gear auxiliary shaft gear, a three-gear auxiliary shaft gear, a four-gear auxiliary shaft gear and a reverse gear from left to right, a single-ratchet wheel is arranged between the first-gear auxiliary shaft gear and the five-gear auxiliary shaft gear, wherein the first-gear auxiliary shaft gear is sleeved on the single-ratchet wheel, and the five-gear auxiliary shaft gear, the three-gear auxiliary shaft gear, the four-gear auxiliary shaft gear and the reverse gear are fixedly connected to the auxiliary shaft.

In the five-gear gearbox structure, the gear shifting levers and the gear shifting forks are three, wherein the first gear shifting lever controls the first double-ratchet wheel, the second gear shifting lever controls the second double-ratchet wheel, and the third gear shifting lever controls the single-ratchet wheel.

The ratchet teeth are defined to be helical teeth, and under the thrust of the tooth roots of the helical teeth, the direction of the force faces the root of the ratchet teeth when the working face of the ratchet teeth is stressed due to the angle of the ratchet teeth, so that the gear ratchet teeth and the sleeve ratchet teeth are automatically clamped, and the moment is transmitted;

in the utility model, the technical effect of the matched connection between the gear and the ratchet wheel by adopting the mode is as follows: (1) When clamping is needed, the ratchet wheel and the gear ratchet are easy to engage, and can be prevented from falling off; (2) With a speed difference, the ratchet teeth and the gear teeth are easily disengaged. The specific reasons are as follows: due to the angle of the ratchet, when the working face of the ratchet is stressed, the direction of the force faces the root of the ratchet, so that the ratchet and the gear ratchet are automatically clamped, and torque is transmitted. Because the back angle of the ratchet is gentle, the moment cannot be transmitted, and when the back of the ratchet is stressed, the direction of force is away from the tooth root, so that the ratchet and the gear are away from each other, and the ratchet and the gear are automatically separated.

The technical scheme of the utility model is that a gear shifting method of a specific five-gear compact bicycle transmission comprises 1) when an initial position is a first gear, a gear shifting drum controls a third gear shifting rod to drive a single-ratchet wheel to move leftwards, and a ratchet wheel positioned on the left side of the single-ratchet wheel is in a meshed state with a ratchet wheel positioned on the right side of a first-gear auxiliary shaft gear; other ratchet wheels are in a separation state, the main shaft drives a first-gear main shaft gear to rotate, the first-gear main shaft gear drives a first-gear auxiliary shaft gear, an auxiliary shaft and a reverse gear to rotate, the reverse gear drives a direct-drive gear which is empty sleeved on the main shaft to rotate, and the output sprocket wheel rotates;

2) When the first gear is shifted to the second gear, the gear shifting drum is rotated, the third gear shifting deflector rod drives the single-ratchet to move rightwards, and the ratchet positioned on the left side of the single-ratchet is separated from the ratchet positioned on the right side of the first gear auxiliary shaft gear; simultaneously, the second gear shifting deflector rod drives the second double-ratchet wheel to move on the right, and a ratchet wheel positioned on the right of the second double-ratchet wheel is meshed with a ratchet wheel on the left of the direct-drive gear; the power is directly rotated through an output chain wheel fixed on the direct-drive gear, and the first double-ratchet wheel and the single-ratchet wheel are both in a ratchet separation state;

3) When the gear is shifted from the second gear to the third gear, the gear shifting drum is rotated, the third gear shifting deflector rod does not generate displacement movement, the second gear shifting deflector rod drives the second double-ratchet wheel to move leftwards, and the ratchet wheel on the right side of the second double-ratchet wheel is separated from the ratchet wheel on the left side of the direct-drive gear; simultaneously, the first gear shifting deflector rod drives the first double-ratchet wheel to move rightwards, a ratchet wheel positioned on the right side of the first double-ratchet wheel is meshed with a ratchet wheel on the left side of the three-gear main shaft gear, the three-gear main shaft gear drives the three-gear auxiliary shaft gear to rotate, the three-gear auxiliary shaft gear drives the auxiliary shaft and the reverse gear to rotate, and the reverse gear drives the direct-drive gear sleeved on the main shaft to rotate, so that the output sprocket wheel rotates;

4) When the gear is shifted from the three gear to the four gear, the gear shifting drum is rotated, the first gear shifting deflector rod drives the first double-ratchet wheel to move leftwards, and the ratchet wheel positioned on the right side of the first double-ratchet wheel is separated from the ratchet wheel positioned on the left side of the three-gear main shaft gear; simultaneously, the second gear shifting deflector rod drives the second double-ratchet wheel to move leftwards, a ratchet wheel positioned at the left side of the second double-ratchet wheel is meshed with a ratchet wheel positioned at the right side of the four-gear main shaft gear, the four-gear main shaft gear drives the four-gear auxiliary shaft gear to rotate, the four-gear auxiliary shaft gear drives the auxiliary shaft and the reverse gear to rotate, the reverse gear drives the direct-drive gear sleeved on the main shaft to rotate, and the output sprocket wheel rotates;

5) When the gear is shifted from the fourth gear to the fifth gear, the gear shifting drum is rotated, the second gear shifting deflector rod drives the second double-ratchet to move rightwards, and the ratchet positioned on the left side of the second double-ratchet is separated from the ratchet positioned on the right side of the four-gear main shaft gear; simultaneously, the first gear shifting deflector rod drives the first double-ratchet wheel to move leftwards, and a ratchet wheel positioned at the left side of the first double-ratchet wheel is meshed with a ratchet wheel positioned at the right side of the five-gear main shaft gear; the five-gear main shaft gear drives the five-gear auxiliary shaft gear to rotate, the five-gear auxiliary shaft gear drives the auxiliary shaft and the reverse gear to rotate, the reverse gear drives the direct-drive gear which is empty sleeved on the main shaft to rotate, and the output sprocket wheel rotates;

6) When the gear is shifted from the fifth gear to the fourth gear, the gear shifting drum is reversely rotated, the first gear shifting deflector rod drives the first double-ratchet wheel to move rightwards, and the ratchet wheel positioned on the left side of the first double-ratchet wheel is separated from the ratchet wheel positioned on the right side of the fifth gear main shaft gear; simultaneously, the second gear shifting deflector rod drives the second double-ratchet wheel to move leftwards, and a ratchet wheel positioned at the left side of the second double-ratchet wheel is meshed with a ratchet wheel positioned at the right side of the four-gear main shaft gear; the four-gear main shaft gear drives the four-gear auxiliary shaft gear to rotate, the four-gear auxiliary shaft gear drives the auxiliary shaft and the reverse gear to rotate, the reverse gear drives the direct-drive gear which is empty sleeved on the main shaft to rotate, and the output sprocket wheel rotates;

7) When the gear is shifted from the fourth gear to the third gear, the gear shifting drum is reversely rotated, the second gear shifting deflector rod drives the second double-ratchet to move rightwards, and the ratchet positioned on the left side of the second double-ratchet is separated from the ratchet positioned on the right side of the fourth-gear main shaft gear; simultaneously, the first gear shifting deflector rod drives the first double-ratchet wheel to move rightwards, and a ratchet wheel positioned on the right side of the first double-ratchet wheel is meshed with a ratchet wheel on the left side of the three-gear main shaft gear; the three-gear main shaft gear drives the three-gear auxiliary shaft gear to rotate, the three-gear auxiliary shaft gear drives the auxiliary shaft and the reverse gear to rotate, the reverse gear drives the direct-drive gear which is empty sleeved on the main shaft to rotate, and the output sprocket wheel rotates;

8) When the gear is shifted from the third gear to the second gear, the gear shifting drum is reversely rotated, the first gear shifting deflector rod drives the first double-ratchet wheel to move leftwards, and the ratchet wheel positioned on the right side of the first double-ratchet wheel is separated from the ratchet wheel positioned on the left side of the third-gear main shaft gear; simultaneously, the second gear shifting deflector rod drives the second double-ratchet wheel to move rightwards, and the ratchet wheel positioned at the right side of the second double-ratchet wheel is meshed with the ratchet wheel positioned at the left side of the direct-drive gear; the direct-drive gear directly rotates through an output sprocket fixed on the direct-drive gear.

9) When the gear is shifted from the second gear to the first gear, the gear shifting drum is reversely rotated, the second gear shifting deflector rod drives the second double-ratchet wheel to move leftwards, and the ratchet wheel positioned on the right side of the second double-ratchet wheel is separated from the ratchet wheel positioned on the left side of the direct-drive gear; simultaneously, the third gear shifting deflector rod drives the single-ratchet wheel to move leftwards, and a ratchet wheel positioned at the left side of the single-ratchet wheel is meshed with a ratchet wheel positioned at the right side of the first gear auxiliary shaft gear; the first-gear main shaft gear drives the first-gear auxiliary shaft gear to rotate, the first-gear auxiliary shaft gear drives the auxiliary shaft and the reverse gear to rotate, the reverse gear drives the direct-drive gear which is empty sleeved on the main shaft to rotate, and the output sprocket wheel rotates;

10 In different initial states, the ratchet engagement position corresponds to the specific state described above.

By adopting the gear shifting method of the technical scheme, the operation is simple, the gear shifting operation is performed in the gear shifting process, and the first gear meshing is automatically completed and disengaged after the second gear is completed. The gear shifting mode can shift gears under the condition of load, and the gear shifting at any time is realized. Meanwhile, the gear shifting process is simple to operate, and the safety during gear shifting is greatly improved. And the gear shifting process time is short, and the gear shifting is realized by shifting the gear shifting drum wheel.

When the gear is shifted, the gear of the gear drives the ratchet wheel of the gear to rotate, and when the gear is shifted, the rotating speed of the ratchet wheel of the gear is high, the stress surface of the ratchet wheel becomes the tooth back, and the direction of force generated by the tooth back is far away from the tooth root, so that the gear of the gear can be pushed to the direction far away from the ratchet wheel of the first gear.

The tooth profile of the ratchet teeth mentioned in the present utility model is the same as the "ratchet teeth" in what is known as "ratchet teeth", namely: the angles of the two flanks are different so that one and only one flank can transmit torque. The direction of the ratchet arrangement of the present utility model is different from the conventional one: the ratchet is annular, but the tips of the teeth are directed sideways, with a specific angle being such that torque can be transmitted between the sleeve and the gear.

For the prior art, the technical scheme has the effects that firstly, the spring plate or the torsion spring on the deflector rod is utilized to drive the shifting fork, so that tooth striking or clamping caused by hard contact of the ratchet teeth is avoided; secondly, the bicycle rider's foot-reversing habit is facilitated. Because the spring plate or the torsion spring on the shifting rod drives the shifting fork to control the ratchet wheel to be meshed with the lateral ratchet teeth of the gear, when the inverted foot reverses the main shaft, the back of the tooth between the ratchet wheel and the lateral ratchet teeth of the gear has thrust force, and the spring plate or the torsion spring can enable the ratchet wheel controlled by the shifting fork to be separated from the gear in the axial direction through deformation; thirdly, the gear shifting mechanism has a static gear shifting function, and even in a non-rotary motion state, due to the deformation function of the elastic sheet or the torsion spring on the deflector rod, any gear can be switched to other gears; fourth, the gear is shifted under load, and when the gear is shifted, the gear is automatically separated from the low gear after the high gear enters the gear according to the speed difference principle. During gear reduction, gear reduction can be performed in advance and in an override mode, even when the gear is operated in a high gear, the shift lever can be shifted to a low gear, at the moment, the elastic sheet and the torsion spring on the low gear shift lever deform, a ratchet wheel and a gear lateral ratchet of the low gear are in a semi-clutch state, when the gear is stopped and stepped on, the load is 0, the gear in the high gear is separated from the ratchet wheel in an inertial mode, and when the gear is stepped on again, the ratchet wheel and the gear lateral ratchet of the low gear are immediately combined to transmit torsion.

Drawings

FIG. 1 is a schematic structural view of a spindle;

FIG. 2 is a schematic structural view of a secondary shaft;

FIG. 3 is an assembled schematic view of the main shaft with the main shaft gear assembled with the countershaft with the shift drum assembled thereon;

FIG. 4 is an assembled schematic view of the main shaft assembled with the output sprocket and the auxiliary shaft assembled with the main shaft gear;

FIG. 5 is a schematic rear view of the structure of FIG. 4;

FIG. 6 is a schematic structural view of a direct drive gear;

FIG. 7 is a schematic diagram of a gear configuration including a first gear main shaft gear, a third gear main shaft gear, a fourth gear main shaft gear, a fifth gear main shaft gear, a first gear auxiliary shaft gear; a reversing gear; a three-gear countershaft gear; a fourth gear countershaft gear; five-gear auxiliary shaft gear;

FIG. 8 is a schematic view of the structure of a ratchet wheel; the ratchet comprises a first double-ratchet; a second double-ratchet; a single ratchet;

FIG. 9 is an enlarged schematic view showing the structure of the metal spring plate of the elastic connecting piece;

fig. 10 is an enlarged schematic view showing the structure in which the elastic connection member is a torsion spring.

In the figure, 1 is a main axis; 11 is a first gear spindle gear; 12 is a direct drive gear; 13 is a three-gear spindle gear; 14 is a four-speed spindle gear; 15 is a five-gear main shaft gear; 18 is a first double-ratchet; 19 is a second double-ratchet;

2 is a secondary shaft; 21 is a first gear countershaft gear; 22 is a counter gear; 23 is a three speed countershaft gear; 24 is a four speed countershaft gear; 25 is a five speed countershaft gear; 28 is a single-ratchet;

3 is an output sprocket;

4 is a shift drum; reference numeral 41 denotes a first shift lever; 42 is a second shift lever; 43 is a third shift lever; 44 is a shift drum groove; 45 is a shift fork; 453 is a metal spring; 455 is a fork guide bar; 456 is a torsion spring body; 457 is the torsion spring output end;

51 is an upper fixing plate; 52 is a lower fixing plate;

Detailed Description

The technical scheme of the utility model is further described below by means of the attached drawings and examples.

1-9, a compact bicycle middle shaft gearbox with load speed change comprises a box type gearbox and a gear shifting device, wherein the box type gearbox comprises a box body, a main shaft 1, a countershaft 2 and an output chain wheel 3, the gearbox is a five-gear gearbox, five driving gears of a first-gear main shaft gear 11, a fifth-gear main shaft gear 15, a third-gear main shaft gear 13, a fourth-gear main shaft gear 14 and a direct drive gear 12 are arranged on the main shaft from left to right, a first double-ratchet wheel 18 is arranged between the five-gear main shaft gear and the third-gear main shaft gear, a second double-ratchet wheel 19 is arranged between the fourth-gear main shaft gear 14 and the direct drive gear 12, the first-gear main shaft gear is fixedly connected to the main shaft or integrally formed with the main shaft, the five-gear main shaft gear 15, the third-gear main shaft gear 13, the fourth-gear main shaft gear 14 and the direct drive gear 12 are sleeved on the main shaft 1 in a hollow mode, and the first double-ratchet wheel 18 and the second double-ratchet wheel 19 are sleeved on the main shaft 1 in a sliding mode; a first-gear counter gear 21, a fifth-gear counter gear 25, a three-gear counter gear 23, a four-gear counter gear 24 and a reverse gear 22 are arranged on the counter shaft 2 from left to right, a single-ratchet 28 is arranged between the first-gear counter gear 21 and the fifth-gear counter gear 25, wherein the first-gear counter gear 21 is sleeved on the counter shaft 2 in an empty mode, the five-gear counter gear 25, the three-gear counter gear 23, the four-gear counter gear 24 and the reverse gear 22 are fixedly connected on the counter shaft 2, and the main gear and the counter gear are mutually matched and meshed; a poking groove is arranged between the driven ratchet wheels of the first double-ratchet wheel 18, the second double-ratchet wheel 19 and the single-ratchet wheel 28; the ratchets are helical teeth.

The gear shifting device comprises a gear shifting drum 4, a first gear shifting rod 41, a second gear shifting rod 42 and a third gear shifting rod 43, three gear shifting forks 45, an upper fixing plate 51, a lower fixing plate 52 and a shifting fork guide rod 455, wherein the gear shifting drum is rotationally fixed on a box body, two ends of a main shaft and a secondary shaft are installed on the box body through bearings, the gear shifting rods can be movably fixed on the box body in a left-right moving manner, the rotation center lines of the gear shifting drum and the rotation center lines of the secondary shaft are parallel to each other, the upper fixing plate 51 and the lower fixing plate 52 are all fixed on the box body under the condition of not interfering gear rotation, the shifting fork guide rods 455 are fixed on the upper fixing plate 51 and the lower fixing plate 52, and the shifting fork connecting part 452 is a hollow tube which is movably sleeved on the shifting fork guide rod 455. The two ends of the main shaft 1 and the auxiliary shaft 2 are arranged on the box body through bearings, and the three gear shifting levers of the first gear shifting lever 41, the second gear shifting lever 42 and the third gear shifting lever 43 can move left and right and are movably fixed on the box body;

the gear shifting drum 4 is provided with a gear shifting drum groove 44 on its circumferential surface, the gear shifting fork comprises a lower-section fork part 451 and an upper-section fork connecting part 452, the fork part 451 is clamped in the middle of the ratchet wheel, the front ends of the three gear shifting levers of the first gear shifting lever 41, the second gear shifting lever 42 and the third gear shifting lever 43 are movably fixed in the gear shifting drum groove 44, the rear ends of the three gear shifting levers of the first gear shifting lever 41, the second gear shifting lever 42 and the third gear shifting lever 43 are elastically and movably connected at the fork connecting part 452, namely, the gear shifting lever and the connecting part of the upper-section fork are elastic connecting parts, in this embodiment, the elastic connecting parts are metal elastic pieces 453, the upper ends of the metal elastic pieces 453 are connected with the gear shifting levers 42, and the lower ends of the metal elastic pieces 453 are connected with the gear shifting forks 453.

In the second embodiment, as shown in fig. 10, in the above technical solution, the elastic connection member is a torsion spring, the torsion spring includes a torsion spring body 456 and a torsion spring output end 457, the torsion spring body 456 is fixedly connected to the gear shifting lever 42, and the torsion spring output end 457 clamps the gear shifting fork.

In addition, by adopting the technical scheme of the utility model, the gear shifting deflector rod and the shifting fork guide rod can be movably fixed on the box body in a left-right manner, and the positions of the gear shifting deflector rod and the shifting fork guide rod are not fixed by adopting the fixing plate, so long as the gear shifting deflector rod and the shifting fork guide rod can only move left and right but cannot move up and down and back and forth.

The utility model relates to a gear shifting method of a compact bicycle middle shaft gearbox with load speed change,

1) When the gearbox is in a neutral position, the first double-ratchet wheel, the second double-ratchet wheel and the single-ratchet wheel are in a separated state with the corresponding gears;

2) When the gear is shifted from the neutral gear to the first gear, the gear shifting drum 4 controls the third gear shifting lever 43 to drive the single-ratchet 28 to move leftwards, and the ratchet positioned at the left side of the single-ratchet 28 is in a meshed state with the ratchet positioned at the right side of the first-gear auxiliary shaft gear 21; other ratchet wheels are in a separation state, the main shaft 1 drives the first-gear main shaft gear 11 to rotate, the first-gear main shaft gear 11 drives the first-gear auxiliary shaft gear 21, the auxiliary shaft 2 and the reverse gear 22 to rotate, the reverse gear 22 drives the direct-drive gear which is sleeved on the main shaft 1 to rotate, and the output sprocket 3 rotates;

3) When the gear is shifted from the first gear to the second gear, the gear shifting drum 4 is rotated, and the third gear shifting lever 43 drives the single-ratchet 28 to move rightwards, and the ratchet positioned at the left side of the single-ratchet 28 is separated from the ratchet 21 positioned at the right side of the first gear auxiliary shaft gear; simultaneously, the second gear shifting deflector 42 drives the second double-ratchet 19 to move to the right, and the ratchet positioned on the right of the second double-ratchet 19 is meshed with the ratchet positioned on the left of the direct-drive gear 12; the power is directly rotated through an output chain wheel fixed on the direct-drive gear, and the first double-ratchet wheel and the single-ratchet wheel are both in a ratchet separation state;

4) When the gear is shifted from the second gear to the third gear, the gear shifting drum 4 is rotated, the second gear shifting lever 43 drives the second double-ratchet 19 to move leftwards, and the ratchet on the right side of the second double-ratchet 19 is separated from the ratchet on the left side of the direct-drive gear 12; simultaneously, the first gear shifting deflector 41 drives the first double-ratchet wheel 18 to move rightwards, a ratchet wheel positioned on the right side of the first double-ratchet wheel 18 is meshed with a ratchet wheel positioned on the left side of the three-gear main shaft gear 13, the three-gear main shaft gear 13 drives the three-gear auxiliary shaft gear 23 to rotate, the three-gear auxiliary shaft gear 23 drives the auxiliary shaft 2 and the reverse gear 22 to rotate, the reverse gear 22 drives the direct-drive gear 12 which is sleeved on the main shaft 1 to rotate, and the output sprocket 3 rotates;

5) When the gear is shifted from the third gear to the fourth gear, the gear shifting drum wheel 4 is rotated, the first gear shifting lever 41 drives the first double-ratchet 18 to move leftwards, and the ratchet positioned on the right side of the first double-ratchet 18 is separated from the ratchet positioned on the left side of the third-gear main shaft gear 13; simultaneously, the second gear shifting deflector 42 drives the second double-ratchet 19 to move leftwards, the ratchet wheel positioned at the left side of the second double-ratchet 19 is meshed with the ratchet wheel positioned at the right side of the four-gear main shaft gear 14, the four-gear main shaft gear 14 drives the four-gear auxiliary shaft gear 24 to rotate, the four-gear auxiliary shaft gear 24 drives the auxiliary shaft 2 and the reverse gear 22 to rotate, the reverse gear 22 drives the direct-drive gear 12 which is sleeved on the main shaft to rotate, and the output sprocket 3 rotates;

6) When the gear is shifted from the fourth gear to the fifth gear, the gear shifting drum 4 is rotated, the second gear shifting lever 42 drives the second double-ratchet 19 to move rightwards, and the ratchet positioned at the left side of the second double-ratchet 19 is separated from the ratchet positioned at the right side of the fourth-gear main shaft gear 14; simultaneously, the first gear shifting lever 41 drives the first double-ratchet wheel 18 to move leftwards, and the ratchet wheel positioned at the left side of the first double-ratchet wheel 18 is meshed with the ratchet wheel positioned at the right side of the five-gear main shaft gear 15; the five-gear main shaft gear 15 drives the five-gear auxiliary shaft gear 25 to rotate, the five-gear auxiliary shaft gear 25 drives the auxiliary shaft 2 and the reverse gear 22 to rotate, the reverse gear 22 drives the direct-drive gear 12 which is sleeved on the main shaft 1 to rotate, and the output sprocket 3 rotates;

7) When the gear is shifted from the fifth gear to the fourth gear, the gear shifting drum 4 is reversely rotated, the first gear shifting deflector rod 41 drives the first double-ratchet wheel 18 to move rightwards, and the ratchet wheel positioned on the left side of the first double-ratchet wheel 18 is separated from the ratchet wheel positioned on the right side of the fifth gear main shaft gear 15; simultaneously, the second gear shifting deflector 42 drives the second double-ratchet 19 to move leftwards, and the ratchet wheel positioned at the left side of the second double-ratchet 19 is meshed with the ratchet wheel positioned at the right side of the four-gear main shaft gear 14; the four-gear main shaft gear 14 drives the four-gear auxiliary shaft gear 24 to rotate, the four-gear auxiliary shaft gear 24 drives the auxiliary shaft 2 and the reverse gear 22 to rotate, the reverse gear 22 drives the direct-drive gear 12 which is sleeved on the main shaft 1 to rotate, and the output sprocket 3 rotates;

8) When the gear is shifted from the fourth gear to the third gear, the gear shifting drum 4 is reversely rotated, the second gear shifting deflector rod 43 drives the second double-ratchet wheel 19 to move rightwards, and the ratchet wheel positioned at the left side of the second double-ratchet wheel 19 is separated from the ratchet wheel positioned at the right side of the fourth-gear main shaft gear 14; simultaneously, the first gear shifting lever 41 drives the first double-ratchet wheel 18 to move rightwards, and the ratchet wheel positioned on the right side of the first double-ratchet wheel 18 is meshed with the ratchet wheel positioned on the left side of the three-gear main shaft gear 13; the three-gear main shaft gear 13 drives the three-gear auxiliary shaft gear 23 to rotate, the three-gear auxiliary shaft gear 23 drives the auxiliary shaft 2 and the reverse gear 22 to rotate, the reverse gear 22 drives the direct-drive gear 12 which is sleeved on the main shaft 1 to rotate, and the output sprocket rotates;

9) When the gear is shifted from the third gear to the second gear, the gear shifting drum wheel 4 is reversely rotated, the first gear shifting deflector rod 41 drives the first double-ratchet wheel 18 to move leftwards, and the ratchet wheel positioned on the right side of the first double-ratchet wheel 18 is separated from the ratchet wheel positioned on the left side of the third-gear main shaft gear 13; simultaneously, the second gear shifting deflector 42 drives the second double-ratchet wheel 19 to move rightwards, and the ratchet wheel positioned on the right side of the second double-ratchet wheel 19 is meshed with the ratchet wheel on the left side of the direct-drive gear 12; the direct drive gear 12 is directly rotated by the output sprocket 3 fixed to the direct drive gear 12.

10 When the gear is shifted from the second gear to the first gear, the gear shifting drum 4 is reversely rotated, the second gear shifting deflector rod 42 drives the second double-ratchet wheel 19 to move leftwards, and the ratchet wheel positioned on the right side of the second double-ratchet wheel 19 is separated from the ratchet wheel positioned on the left side of the direct-drive gear 12; simultaneously, the third gear shifting lever 43 drives the single-ratchet 28 to move leftwards, and the ratchet positioned at the left side of the single-ratchet 28 is meshed with the ratchet positioned at the right side of the first-gear auxiliary shaft gear 21; the first-gear main shaft gear 21 drives the first-gear auxiliary shaft gear 21 to rotate, the first-gear auxiliary shaft gear 21 drives the auxiliary shaft 2 and the reverse gear 22 to rotate, the reverse gear 22 drives the direct-drive gear 12 which is sleeved on the main shaft 1 to rotate, and the output sprocket 3 rotates;

11 When the gear is shifted down from the first gear to the neutral gear, the shift drum 4 is rotated in the reverse direction, the first double-ratchet 18, the second double-ratchet 19, and still in the disengaged state; the gear shifting drum 4 controls the third gear shifting lever 43 to drive the single-ratchet wheel 28 to move rightwards, and the single-ratchet wheel 28 is in a separated state;

12 In different initial states, the ratchet engagement position corresponds to the specific state described above.

The description of the specific embodiments is only intended to aid in understanding the method of the utility model and its core concept, and it should be pointed out that it is possible for a person skilled in the art to make several improvements and modifications to the utility model, such as simple changes in the length of the sleeve and the angle of inclination of the tooth flanks, the number of teeth of the ratchet teeth of the gear and the number of teeth of the ratchet teeth of the sleeve, without departing from the principles of the utility model, which also fall within the scope of protection of the claims of the utility model.

Claims (7)

1. The compact bicycle middle shaft gearbox comprises a box type gearbox and a gear shifting device, wherein the box type gearbox comprises a box body, a main shaft, a countershaft and an output sprocket, a plurality of main shaft gears and a driving ratchet wheel are arranged on the main shaft, a plurality of countershaft gears and driven ratchet wheels are arranged on the countershaft, a shifting groove is formed in the middle of the driving ratchet wheel and the driven ratchet wheel, and the main shaft gears and the countershaft gears are meshed in a matched mode; the gear shifting device comprises a gear shifting drum, a gear shifting rod and a gear shifting fork, wherein the gear shifting drum is rotationally fixed on a box body, two ends of a main shaft and a secondary shaft are installed on the box body through bearings, the gear shifting rod can be movably fixed on the box body in a left-right moving mode, the rotation center line of the gear shifting drum is parallel to that of the secondary shaft, a gear shifting drum wheel groove is formed in the circumferential surface of the gear shifting drum, the gear shifting fork comprises a lower-section shifting fork part and an upper-section shifting fork connecting part, the shifting fork part is clamped in a shifting groove in the middle of a ratchet wheel, the front end of the gear shifting rod is movably fixed in the gear shifting drum groove, and the rear end of the gear shifting rod is movably connected with the shifting fork connecting part, and the gear shifting device is characterized in that: one of the main shaft gears is a direct drive gear, and the output chain wheel is fixed on the direct drive gear; at least one of the driving ratchet wheel and the driven ratchet wheel is a double-ratchet wheel, two main shaft gears or two auxiliary shaft gears with single ratchet teeth are arranged on two sides of the double-ratchet wheel, and the double-ratchet wheel moves left and right on the main shaft or the auxiliary shaft and is respectively meshed with/separated from the two main shaft gears or the two auxiliary shaft gears of the single ratchet teeth through ratchet teeth on two sides; the connecting piece of gear shifting driving lever and shift fork is elastic connecting piece.

2. The compact bicycle bottom bracket transmission with load shifting of claim 1, wherein: the elastic connecting piece is a metal spring piece, the upper end of the metal spring piece is fixedly connected to the gear shifting rod, and the lower end of the metal spring piece movably clamps the gear shifting fork.

3. The compact bicycle bottom bracket transmission with load shifting of claim 1, wherein: the elastic connecting piece is a torsion spring, the torsion spring comprises a torsion spring body and a torsion spring output end, the torsion spring body is fixedly connected to the gear shifting deflector rod, and the gear shifting fork is movably clamped by the torsion spring output end.

4. The compact bicycle bottom bracket transmission with load shifting of claim 1, wherein: the gear shifting device further comprises a fixing plate and a shifting fork guide rod, wherein the fixing plate is fixed on the box body, the shifting fork guide rod is fixed on the fixing plate or directly fixed on the box body, the shifting fork connecting portion is a hollow tube, and the hollow tube is movably sleeved on the shifting fork guide rod.

5. A compact bicycle bottom bracket transmission with load shifting as defined in claim 2 or 3, wherein: the gear box is a five-gear box, a first-gear main shaft gear, a five-gear main shaft gear, a three-gear main shaft gear, a four-gear main shaft gear and a direct drive gear are arranged on the main shaft from left to right, a first double-ratchet wheel is arranged between the five-gear main shaft gear and the three-gear main shaft gear, a second double-ratchet wheel is arranged between the four-gear main shaft gear and the direct drive gear, wherein the first-gear main shaft gear is fixedly connected to the main shaft, the five-gear main shaft gear, the three-gear main shaft gear, the four-gear main shaft gear and the direct drive gear are sleeved on the main shaft in an empty mode, and the first double-ratchet wheel and the second double-ratchet wheel are sleeved on the main shaft in a sliding mode; the auxiliary shaft is provided with a first-gear auxiliary shaft gear, a five-gear auxiliary shaft gear, a three-gear auxiliary shaft gear, a four-gear auxiliary shaft gear and a reverse gear from left to right, a single-ratchet wheel is arranged between the first-gear auxiliary shaft gear and the five-gear auxiliary shaft gear, wherein the first-gear auxiliary shaft gear is sleeved on the auxiliary shaft in an empty mode, and the five-gear auxiliary shaft gear, the three-gear auxiliary shaft gear, the four-gear auxiliary shaft gear and the reverse gear are fixedly connected to the auxiliary shaft.

6. The compact bicycle bottom bracket transmission with load shifting of claim 5, wherein: the gear shifting rod and the gear shifting fork are three, wherein the first gear shifting rod controls the first double-ratchet wheel, the second gear shifting rod controls the second double-ratchet wheel, and the third gear shifting rod controls the single-ratchet wheel.

7. The compact bicycle bottom bracket transmission with load shifting of claim 6, wherein: the ratchets are helical teeth.