TW202400465A - Rear chain wheel for human-powered vehicle - Google Patents

Abstract

The invention provides a rear sprocket for a human-powered vehicle, which can improve strength and rigidity and can realize light weight. A rear sprocket (47) is used for a bicycle (1). The rear sprocket (47) is provided with an outer ring-shaped body (57), a plurality of sprocket teeth (59), an inner ring-shaped body (61), and a connecting arm (63). The connecting arm (63) has a radially outer half section (65) and a radially inner half section (67). The second circumferential width (W2) of the radially inner half section (67) is smaller than the first circumferential width (W1) of the radially outer half section (65). The connecting arm (63) is formed in a tapered shape from a first radial position (RP1) toward a second radial position (RP2).

Description

Rear sprocket for human powered vehicles

The invention relates to a rear sprocket for a human-powered vehicle.

The subsequent sprocket disclosed in Patent Document 1 includes an outer annular body, a plurality of sprocket teeth, an inner annular body, and a plurality of connecting arms. A plurality of sprocket teeth extend radially outward from the outer peripheral surface of the outer annular body. The inner annular body is connected to the sprocket support body in an assembled state where the rear sprocket is mounted on the hub assembly.

Each of the plurality of connecting arms extends in the radial direction between the outer annular body and the inner annular body. The circumferential width of each of the plurality of connecting arms has a shape that becomes smaller from the radially inner side toward the radial outer side. [Prior technical literature] [Patent Document]

[Patent Document 1] Chinese Patent Application Publication No. 102328724

[Problem to be solved by the invention]

In the previous rear sprocket, a rivet hole for connecting a certain rear sprocket to an adjacent rear sprocket is provided on the radially outer part of the connecting arm. Therefore, when the circumferential width of the radially outer portion is small, the strength and rigidity around the rivet holes of the connecting arms may be insufficient.

An object of the present invention is to provide a rear sprocket for human-driven vehicles that can improve strength and rigidity and achieve lightweight. [Technical means to solve problems]

Regarding the first aspect of the present invention, the rear sprocket for a human-driven vehicle can be used for a human-driven vehicle having an axial center plane. The rear sprocket for a human-driven vehicle has a rotation center axis, an axial outer surface, and an axial inner surface. The axial inner side is axially axially aligned with the axis of the rotation center and is located on the opposite side to the axial outer side. The axial inner side is configured to face the axial center surface in the axial direction when installed on a human-driven vehicle.

The rear sprocket for a human-driven vehicle includes an outer annular body, a plurality of sprocket teeth, an inner annular body, and at least one connecting arm. A plurality of sprocket teeth extend radially outward from the outer peripheral surface of the outer annular body in the radial direction of the rotation center axis. The inner annular body is configured as a sprocket supporting body connected to the wheel housing assembly in a torque-transmissible manner when the rear sprocket is mounted on the wheel housing assembly.

At least one connecting arm extends in the radial direction between the outer annular body and the inner annular body. At least one connecting arm has a radially outer half section and a radially inner half section. The radially inner half is located radially inward from the radially outer half.

Each of the plurality of sprocket teeth has a maximum radial length and a maximum axial length. The maximum radial length is defined in the radial direction. The maximum axial length is defined in the axial direction. The maximum axial length is shorter than the maximum radial length.

The radially outer half section has a first circumferential width. The first circumferential width is defined by the first radial position of the rotation center axis. The radially inner half section has a second circumferential width. The second circumferential width is defined by the second radial position of the rotation center axis. The second circumferential width is smaller than the first circumferential width.

At least one connecting arm is formed in a tapered shape from the first radial position toward the second radial position. The outer annular body, the plurality of sprocket teeth, the inner annular body and at least one connecting arm are formed as a single integral member.

In the first aspect of the rear sprocket for a human-driven vehicle, since the second circumferential width of the radially inner half is smaller than the first circumferential width of the radially outer half, the rear sprocket can be realized in the radially inner half. Lightweight wheels. In addition, since the first circumferential width of the radially outer half section is larger than the second circumferential width of the radially inner half section, the strength and rigidity of the radially outer half section can be improved. That is, the strength and rigidity of the rear sprocket for human-driven vehicles can be improved, and the weight can be reduced.

Regarding the second aspect of the present invention, the rear sprocket of the human-driven vehicle of the first aspect is configured such that at least one connecting arm includes a plurality of connecting arms.

In the rear sprocket for a human-powered vehicle of the second aspect, in each of the plurality of connecting arms, the second circumferential width of the radially inner half is smaller than the first circumferential width of the radially outer half. With this structure, the strength and rigidity of the radially outer half section can be improved, and the weight of the radially inner half section can be achieved.

Regarding the third aspect of the present invention, the rear sprocket of the human-driven vehicle of the second aspect is configured as a plurality of connecting arms, and the total number of the connecting arms is four or more.

In the third aspect of the rear sprocket for a human-driven vehicle, the strength and rigidity of the radially outer half can be appropriately increased, and the radially inner half can be appropriately lightweight.

Regarding the fourth aspect of the present invention, the rear sprocket of the human-driven vehicle of at least one of the first to third aspects is configured such that at least one connecting arm has a rivet hole. The rivet holes are arranged at a first radial position of a first circumferential width.

In the fourth aspect of the rear sprocket for a human-driven vehicle, since the rivet hole is provided at the first radial position of the first circumferential width, even if the rivet hole is provided in the radially outer half, the required area around the rivet hole can be ensured. The strength and rigidity. Furthermore, by fixing the rear sprocket to the adjacent rear sprocket through the rivet hole in the radially outer half, the axial strength and rigidity of the rear sprocket assembly can be improved.

Regarding the fifth aspect of the present invention, the rear sprocket of the human-driven vehicle of the fourth aspect is configured as follows. Rivet holes have apertures. The ratio of the first circumferential width to the hole diameter is 2.5 or more.

In the fifth aspect of the rear sprocket for a human-driven vehicle, even if rivet holes are provided in the radially outer half, by setting the ratio of the first circumferential width to the hole diameter to 2.5 or more, it is possible to secure the required area around the rivet holes. The strength and rigidity.

Regarding the sixth aspect of the present invention, the rear sprocket of the human-powered vehicle of any one of the first to fifth aspects is configured as follows. The inner annular body has a spline portion. The spline portion is configured to engage with the sprocket support body of the wheel housing assembly in the assembled state.

In the rear sprocket for a human-driven vehicle according to the sixth aspect, the drive torque can be reliably transmitted from the rear sprocket to the wheel housing assembly through the spline portion of the inner annular body.

Regarding the seventh aspect of the present invention, the rear sprocket of the human-driven vehicle of any one of the first to sixth aspects is configured such that the first circumferential width is 11 mm or more.

In the rear sprocket for a human-powered vehicle according to the seventh aspect, by setting the first circumferential width to 11 mm or more, the strength and rigidity of the radially outer half can be appropriately increased.

Regarding the eighth aspect of the present invention, the rear sprocket of the human-driven vehicle of any one of the first to seventh aspects is configured such that the first circumferential width is 20 mm or less.

In the rear sprocket for a human-driven vehicle according to the eighth aspect, by setting the first circumferential width to 20 mm or less, an increase in the weight of the radially outer half can be suppressed.

Regarding the ninth aspect of the present invention, the rear sprocket of the human-driven vehicle of any one of the first to eighth aspects is configured such that the second circumferential width is 5 mm or more.

In the rear sprocket for a human-powered vehicle according to the ninth aspect, by setting the second circumferential width to 5 mm or more, the strength and rigidity of the radially inner half can be ensured.

Regarding the tenth aspect of the present invention, the rear sprocket of the human-driven vehicle of any one of the first to ninth aspects is configured such that the second circumferential width is 10 mm or less.

In the rear sprocket for a human-driven vehicle according to the tenth aspect, by setting the second circumferential width to 10 mm or less, the weight of the radially inner half can be appropriately reduced.

Regarding the eleventh aspect of the present invention, the rear sprocket of the human-driven vehicle of any one of the first to tenth aspects is configured as follows. The plurality of sprocket teeth includes a plurality of downshift promoting teeth. A plurality of downshift promoting gears are configured to promote the downshifting action of the drive chain moving from the small sprocket adjacent to the rear sprocket to the rear sprocket.

The plurality of downshift promoting teeth include downshift starting teeth and downshift recessed teeth. The downshift start gear is configured to engage with the drive chain first during the downshift operation. The downshift recessed teeth are located on the downstream side of the downshift start teeth in the driving rotation direction of the rear sprocket and are arranged adjacent to the downshift start teeth.

In the circumferential direction of the rotation center axis, no other sprocket teeth are arranged between the downshift start teeth and the downshift recessed teeth. The downshift recessed tooth has a downshift recess. The downshift recess is axially recessed from the axial outer surface toward the axial inward surface and is provided on the axially outer surface of the downshift recess tooth.

In the rear sprocket for a human-driven vehicle according to the eleventh aspect, since the plurality of sprocket teeth includes the plurality of downshift accelerating teeth, the impact during the downshift operation can be mitigated and the downshift operation can be smoothly performed.

Regarding the twelfth aspect of the present invention, the rear sprocket of the human-driven vehicle of the eleventh aspect is configured as follows. The first axial recessed portion is axially recessed from the axial inner surface toward the axial outer surface and is provided on the axial inner surface of the downshift start tooth. The first axial recess is arranged at least on the tooth tip of the downshift starting tooth.

In the rear sprocket for a human-driven vehicle according to the twelfth aspect, since the first axial recess is provided on the axially inner surface of the downshift start tooth, the impact during the downshift operation can be appropriately mitigated, and the downshift can be performed more smoothly. action.

Regarding the thirteenth aspect of the present invention, the rear sprocket of the human-driven vehicle of the first or twelfth aspect is configured as follows. The downshift recess has a first downshift recess and a second downshift recess. Each of the first downshift recess and the second downshift recess is provided on the axially outer surface of the downshift recessed tooth so as to be recessed from the axial outer surface toward the axial inward surface in the axial direction.

The downshift first recess has a first recess bottom surface. The downshift second recessed portion has a second recessed portion bottom surface. The first axial depth is defined in the axial direction from the axial outer surface of the outer annular body to the bottom surface of the first recess. The second axial depth is defined in the axial direction from the axial outer surface of the outer annular body to the bottom surface of the second recess. The first axial depth is smaller than the second axial depth.

In the rear sprocket for a human-driven vehicle according to the thirteenth aspect, since the downshift recess has the first downshift recess and the second downshift recess, the impact during the downshift can be moderately mitigated and the downshift can be performed more smoothly. .

Regarding the fourteenth aspect of the present invention, the rear sprocket of the human-driven vehicle of the thirteenth aspect is configured as follows. The downshift recessed tooth has a first tooth tip. The first downshift concave portion reaches the first tooth tip of the downshift concave portion tooth.

In the rear sprocket for a human-driven vehicle according to the fourteenth aspect, since the first recessed portion of the downshift reaches the first tooth tip of the downshift recessed tooth, the impact during the downshifting action can be moderately mitigated, and the downshifting action can be performed more smoothly. .

Regarding the fifteenth aspect of the present invention, the rear sprocket of the human-driven vehicle of the thirteenth or fourteenth aspect is configured as follows. The downshift recessed tooth has a driving surface and a non-driving surface provided on the opposite side of the driving surface in the circumferential direction. The first downshift recess reaches the driving surface of the downshift recessed tooth.

In the rear sprocket for a human-driven vehicle according to the fifteenth aspect, since the downshift first concave portion reaches the driving surface of the downshift concave portion teeth, the impact during the downshift operation can be moderately mitigated, and the downshift operation can be performed more smoothly.

Regarding the 16th aspect of the present invention, in the human-driven vehicle of the 15th aspect, the rear sprocket is configured such that the second downshift recessed portion does not reach the driving surface of the downshift recessed portion teeth.

In the rear sprocket for a human-driven vehicle according to the sixteenth aspect, since the second downshift recessed portion does not reach the driving surface of the downshift recessed tooth, the impact during the downshifting operation can be moderately mitigated, and the downshifting operation can be performed smoothly.

Regarding the seventeenth aspect of the present invention, the rear sprocket of the human-driven vehicle of any one of the thirteenth to sixteenth aspects is configured such that no other concave portion is arranged between the first downshift recessed portion and the second downshift recessed portion. The gear first recessed portion and the downshift second recessed portion are arranged adjacent to each other.

In the rear sprocket for a human-powered vehicle according to the seventeenth aspect, since the first downshift recess and the second downshift recess are arranged adjacent to each other, the impact during the downshift can be appropriately mitigated and the downshift can be performed more smoothly. .

Regarding the eighteenth aspect of the present invention, the rear sprocket of the human-driven vehicle of any one of the first to seventeenth aspects is configured as follows. The plurality of sprocket teeth includes a plurality of upshift promoting teeth. A plurality of upshift promoting teeth are formed to promote the upshifting action. The upshifting action is the movement of the drive chain from the rear sprocket to the small sprocket adjacent to the rear sprocket.

In the rear sprocket for a human-driven vehicle according to the eighteenth aspect, since the plurality of sprocket teeth includes a plurality of upshift accelerating teeth, the impact during the upshifting operation can be mitigated and the upshifting operation can be performed smoothly.

Regarding the 19th aspect of the present invention, the rear sprocket of the human-driven vehicle of the 18th aspect is configured as follows. The plurality of upshift promoting teeth include upshift shift teeth, upshift start teeth, and upshift recessed teeth. The upshift shift tooth is configured to shift the drive chain toward the small sprocket during the upshift operation. The upshift start gear is configured to be the first to disengage from the drive chain during the upshift action.

The upshift start tooth has an upshift first recess. The first upshift recessed portion is axially recessed from the axial outer side to the axial inward side and is provided on the axially outer surface of the upshift start tooth. In the circumferential direction of the rotation center axis, there are no other sprocket teeth between the upshift start teeth and the upshift shift teeth. The upshift start teeth are between the upshift shift teeth in the driving rotation direction of the rear sprocket. On the upstream side, it is arranged adjacent to the upshift gear.

The upshift recessed tooth has a second upshift recess. The second upshift recessed portion is axially recessed from the axial outer side to the axial inward side and is provided on the axially outer surface of the upshift recessed tooth. In the circumferential direction, no other sprocket teeth are arranged between the upshift recessed teeth and the upshift start teeth. The upshift recessed teeth are located upstream of the upshift start teeth in the driving rotation direction and are arranged adjacent to the upshift start teeth.

In the rear sprocket for a human-driven vehicle according to the nineteenth aspect, since the plurality of upshift promoting teeth include upshift shift teeth, upshift start teeth, and upshift recessed teeth, the impact during the upshift operation can be appropriately mitigated, and Upshifting can be performed more smoothly.

Regarding the 20th aspect of the present invention, the rear sprocket of the human-driven vehicle of the 19th aspect is configured as follows. The second axial recess is provided on the axial inner surface of the upshift tooth in an axial direction such that it is recessed from the axial inner surface toward the axial outer surface. The second axial recess is arranged at least on the tooth tip of the upshift tooth.

In the rear sprocket for a human-driven vehicle according to the 20th aspect, since the second axial recess is provided on the axially inner surface of the upshift shift tooth, the impact during the upshift operation can be moderately mitigated, and the upshift can be performed more smoothly. file action. [Effects of the invention]

According to the present invention, the strength and rigidity of the rear sprocket for a human-driven vehicle can be improved, and the rear sprocket for a human-driven vehicle can be reduced in weight.

As shown in FIG. 1 , a bicycle 1 according to the embodiment of the present invention has a drive chain 3 , a frame 5 , a handlebar 7 , a front wheel 9 , a rear wheel 11 , a speed change operating device 13 , a drive part 15 and a front fork 17 . The bicycle 1 further has a front derailleur 21 and a rear derailleur 23 . The bicycle 1 is an example of the human-powered vehicle of the present invention. As shown in Figure 2, the bicycle 1 has an axial center plane P.

As shown in FIG. 1 , the front fork 17 is rotatably mounted on the vehicle frame 5 . The handle 7 is fixed to the front fork 17 . The front wheel 9 is rotatably mounted to the front fork 17 via the front wheel housing assembly 18 . The rear wheel 11 is rotatably mounted to the rear portion of the vehicle frame 5 via the rear wheel housing assembly 19 . The front tire 9a is attached to the front wheel 9. The rear tire 11a is attached to the rear wheel 11.

The transmission operating device 13 is mounted on the handle 7 . The transmission operating device 13 operates the front derailleur 21 and the rear derailleur 23 via cables. For example, the rear derailleur 23 is mounted on the vehicle frame 5 . The rear derailleur 23 moves the drive chain 3 from a certain rear sprocket to other rear sprockets through the speed change operating device 13 .

The front derailleur 21 is installed on the vehicle frame 5 . The front derailleur 21 moves the drive chain 3 from a certain front sprocket to other front sprockets through the speed change operating device 13 . That is, by operating the transmission operating device 13, the front derailleur 21 is operated, thereby performing an upshift operation and a downshift operation.

The drive unit 15 mainly includes a rear wheel housing assembly 19, a rear sprocket assembly 27, and a crank assembly 29. The driving part 15 may also include the driving chain 3 . The rear wheel housing assembly 19 is installed on the vehicle frame 5 .

The rear wheel 11 is connected to the rear wheel housing assembly 19 . The rear wheel housing assembly 19 rotates integrally with the rear wheel 11 . The rear wheel housing assembly 19 rotates relative to the vehicle frame 5 via a wheel housing shaft (not shown). The rear wheel housing assembly 19 is configured to rotate together with the rear sprocket assembly 27 .

As shown in FIGS. 1 and 2 , the rear sprocket assembly 27 has a rotation center axis X. The rear sprocket assembly 27 rotates around the rotation center axis X. For example, the rear sprocket assembly 27 is rotatably supported by the rear wheel housing assembly 19 . The driving force input from the rider of the bicycle 1 to the crank assembly 29 is transmitted to the rear sprocket assembly 27 via the drive chain 3 . Details of the rear sprocket assembly 27 are described below.

As shown in FIG. 1 , the crank assembly 29 includes a crank arm 31 and a front sprocket assembly 33 . The crank arm 31 is rotatably supported on the lower part of the vehicle frame 5 . The front sprocket assembly 33 is mounted on the crank arm 31 to rotate integrally with the crank arm 31 . The front sprocket assembly 33 has at least one front sprocket.

As shown in FIG. 3 , the rear sprocket assembly 27 has a plurality of rear sprockets 41 to 51 . A plurality of rear sprockets 41 to 51 can be used for the bicycle 1. Each of the plurality of rear sprockets 41 to 51 is engaged with the drive chain 3 . The driving force transmitted from the crank assembly 29 to the drive chain 3 is transmitted to each of the plurality of rear sprockets 41 to 51 .

As shown in FIG. 4 , each of the plurality of rear sprockets 41 to 51 is mounted on the sprocket supporting body 19 a of the rear wheel housing assembly 19 so as to rotate integrally with the sprocket supporting body 19 a of the rear wheel housing assembly 19 .

In this embodiment, an example is shown in which the plurality of rear sprockets 41 to 51 include 11 rear sprockets. The first to eleventh rear sprockets 41 to 51 are arranged coaxially with respect to the rotation center axis X. The first to eleventh rear sprockets 41 to 51 are arranged in an axial direction with respect to the rotation center axis X. In the third to ninth rear sprockets 43 to 49, spacers 28a to 28f are arranged between two adjacent sprockets.

The seventh to ninth rear sprockets 47 to 49 are connected to each other by the first rivet 53a. The eighth to tenth rear sprockets 48 to 50 are connected to each other by the second rivet 53b. The ninth to tenth rear sprockets 49 to 50 are connected to each other by the third rivet 53c. The 10th to 11th rear sprockets 50-51 are connected to each other by the 4th rivet 53d. The first to eleventh rear sprockets 41 to 51 and the spacers 28a to 28f are connected to each other by the connecting member 53e.

In this embodiment, the seventh and eighth rear sprockets 47 and 48 have the characteristic structure of the present invention. Hereinafter, the seventh and eighth rear sprockets 47 and 48 will be described in detail.

·7th rear sprocket As shown in FIGS. 5 , 6A and 6B, the seventh rear sprocket 47 has a rotation center axis X, a first axial outer surface 47a and a first axial inner surface 47b. The rotation center axis X is concentric with the rotation center axis of the rear sprocket assembly 27 described above. As shown in FIGS. 5 and 6A , the first axial outer surface 47 a forms the outer surface of the seventh rear sprocket 47 in the axial direction of the rotation center axis X.

As shown in FIGS. 5 and 6B , the first axial inner surface 47b forms the inner surface of the seventh rear sprocket 47 in the axial direction of the rotation center axis X. The first axial inner surface 47b is provided on the opposite side to the first axial outer surface 47a in the axial direction of the rotation center axis X. The first axial inner side surface 47b is configured to face the axial center plane P shown in FIG. 2 in the axial direction of the rotation center axis X when mounted on the bicycle 1 .

As shown in FIGS. 6A and 6B , the seventh rear sprocket 47 includes a first outer annular body 57 , a plurality of first sprocket teeth 59 , a first inner annular body 61 , and at least one first connecting arm 63 . The first outer annular body 57 , the plurality of first sprocket teeth 59 , the first inner annular body 61 and at least one first connecting arm 63 are formed as a single integral member.

The plurality of first sprocket teeth 59 extend radially outward from the outer peripheral portion 57a of the first outer annular body 57 in the radial direction of the rotation center axis X. In this embodiment, the total number of teeth of the plurality of first sprocket teeth 59 is 26.

As shown in FIG. 6C , each of the plurality of first sprocket teeth 59 has a first maximum radial length L1 and a first maximum axial length L2. The first maximum radial length L1 is defined in the radial direction of the rotation center axis X. For example, the first maximum radial length L1 is the length from the outer peripheral portion 57a of the first outer annular body 57 to the tooth tips 59a of the plurality of first sprocket teeth 59 in the radial direction of the rotation center axis X. The outer peripheral portion 57a of the first outer annular body 57 is defined by the tooth base circles 57b of the plurality of first sprocket teeth 59.

The first maximum axial length L2 is defined in the axial direction of the rotation center axis X. For example, the first maximum axial length L2 is the axial direction of the rotation center axis The maximum length between sides 47b.

The first maximum axial length L2 is the maximum length between the first axial outer surface 47a and the first axial inner surface 47b at the position of the outer peripheral portion 57a of the first outer annular body 57. The first maximum axial length L2 is shorter than the first maximum radial length L1.

As shown in FIG. 4 , the first inner annular body 61 is configured to be connected to the rear wheel housing assembly 19 in a torque-transmissible manner when the seventh rear sprocket 47 is mounted on the rear wheel housing assembly 19 . Sprocket support 19a.

As shown in FIG. 5 , FIG. 6A and FIG. 6B , the first inner annular body 61 has a first spline hole 61 a. The first spline hole 61a forms the inner peripheral surface of the first inner annular body 61. As shown in FIG. 4 , the first spline hole 61 a is configured to engage with the sprocket support 19 a of the rear wheel housing assembly 19 when the seventh rear sprocket 47 is mounted on the rear wheel housing assembly 19 . For example, the sprocket support 19a is a cylindrical spline shaft.

As shown in FIG. 5 , FIG. 6A and FIG. 6B , at least one first connecting arm 63 extends in the radial direction of the rotation center axis X between the first outer annular body 57 and the first inner annular body 61 .

As shown in FIGS. 6A and 6B , at least one first connecting arm 63 is formed in a tapered shape from the first radial position RP1 toward the second radial position RP2. For example, at least one first connecting arm 63 is formed in a tapered shape such that the first circumferential width W1 of the first connecting arm 63 gradually becomes smaller from the first radial position RP1 toward the second radial position RP2. Details of the first circumferential width W1 are described below.

As shown in FIGS. 6A and 6B , at least one first connecting arm 63 has a first radially outer half section 65 and a first radially inner half section 67 . At least one first connecting arm 63 has a first rivet hole 69 . The first rivet 53a shown in FIG. 4 is inserted into the first rivet hole 69.

At least one first connecting arm 63 includes a plurality of first connecting arms 63 . It is preferable that the total number of the plurality of first connecting arms 63 is 4 or more. In the embodiment, the total number of the plurality of first connecting arms 63 is seven.

As shown in FIGS. 6A and 6B , the first radially outer half section 65 is provided between the first outer annular body 57 and the first radially inner half section 67 in the radial direction of the rotation center axis X. The first radially outer half section 65 is formed integrally with the first outer annular body 57 and the first radially inner half section 67 .

The first radially outer half section 65 has a first circumferential width W1. The first circumferential width W1 is defined by the first radial position RP1 of the rotation center axis X. The first circumferential width W1 is the length of the arc extending in the circumferential direction of the rotation center axis X at the first radial position RP1 of the rotation center axis X. For example, the first circumferential width W1 is 11 mm or more. The first circumferential width W1 is 20 mm or less. That is, the first circumferential width W1 is 11 mm or more and 20 mm or less.

As shown in FIGS. 6A and 6B , the first radially inner half section 67 is located radially inward from the first radially outer half section 65 in the radial direction of the rotation center axis X. The first radially inner half section 67 is provided between the first radially outer half section 65 and the first inner annular body 61 in the radial direction of the rotation center axis X. The first radially inner half section 67 is formed integrally with the first radially outer half section 65 and the first inner annular body 61 .

The first radially inner half section 67 has a second circumferential width W2. The second circumferential width W2 is defined by the second radial position RP2 of the rotation center axis X. The second circumferential width W2 is the length of the arc extending in the circumferential direction of the rotation center axis X at the second radial position RP2 of the rotation center axis X.

For example, the second circumferential width W2 is smaller than the first circumferential width W1. The second circumferential width W2 is 5 mm or more. The second circumferential width W2 is 10 mm or less. That is, the second circumferential width W2 is 5 mm or more and 10 mm or less.

As shown in FIGS. 6A and 6B , the first rivet hole 69 is provided at the first radial position RP1 of the first circumferential width W1. The first rivet hole 69 has a hole diameter D1. For example, the ratio W1/D1 of the first circumferential width W1 to the hole diameter D1 is 2.5 or more. The ratio W1/D1 of the first circumferential width W1 to the hole diameter D1 is 5.0 or less.

That is, the ratio W1/D1 of the first circumferential width W1 to the hole diameter D1 is 2.5 or more and 5.0 or less. In this embodiment, the first circumferential width W1 is 13.8 mm, and the hole diameter D1 is 4.73. In this case, the ratio W1/D1 of the first circumferential width W1 to the hole diameter D1 is 2.9.

In order to smoothly promote the downshift operation, the above-mentioned seventh rear sprocket 47 is configured as follows. As shown in FIGS. 7A and 7B , the plurality of first sprocket teeth 59 include a plurality of downshift accelerating teeth 59D1 and 59D2. The plurality of first sprocket teeth 59 may further include additional downshift accelerating teeth 59D3. The plurality of downshift promoting teeth 59D1 and 59D2 and the additional downshift promoting tooth 59D3 are configured to promote the downshifting operation. The downshift operation is an operation in which the drive chain 3 moves from the sixth rear sprocket 46 adjacent to the seventh rear sprocket 47 to the seventh rear sprocket 47 . That is, the downshift operation in this embodiment is an operation in which the drive chain 3 moves from the small sprocket 46 adjacent to the rear sprocket 47 to the rear sprocket 47 .

The plurality of downshift accelerating teeth 59D1 and 59D2 include a downshift start tooth 59D1 and a downshift recessed tooth 59D2. The additional downshift accelerating teeth 59D3 include additional downshift recessed teeth 59D3. The downshift start tooth 59D1 is configured to engage with the drive chain 3 first during the downshift operation.

For example, during the downshift operation, the outer link of the drive chain 3 is located at the additional downshift promotion tooth 59D3, and the inner link of the drive chain 3 is located at the downshift promotion tooth 59D2. The outer link of the drive chain 3 first interacts with the downshift. Gear start tooth 59D1 engages.

The downshift start tooth 59D1 is disposed on the most upstream side of the seventh rear sprocket 47 in the drive rotation direction RD among the plurality of downshift accelerating teeth 59D1, 59D2 and the additional downshift accelerating tooth 59D3.

As shown in FIG. 7A , the downshift start tooth 59D1 has a driving surface 59D1a and a non-driving surface 59D1b. The driving surface 59D1a is provided upstream of the seventh rear sprocket 47 in the driving rotation direction RD. The non-driving surface 59D1b is provided on the opposite side of the driving surface 59D1a in the circumferential direction of the rotation center axis X. The axially outer surface of the tooth tip 59D1c is inclined such that the tooth tip 59D1c on the driving surface 59D1a side is located axially inward of the tooth tip 59D1d on the non-driving surface 59D1b side.

As shown in FIG. 7B , the downshift start tooth 59D1 has a first axial recessed portion 59D1e. The first axial recess 59D1e is provided on the first axial inner surface 47b of the downshift start tooth 59D1. For example, the first axial recessed portion 59D1e is provided on the first shaft of the downshift start tooth 59D1 so as to be recessed from the first axial inner side 47b toward the first axial outer side 47a in the axial direction of the rotation center axis X. Inward side 47b. The first axial recessed portion 59D1e is arranged at least on the tooth tip 59D1f of the downshift start tooth 59D1.

The first axial recessed portion 59D1e may be a recessed portion or an inclined portion. The first axial recess 59D1e may extend radially inward from the tooth tip 59D1c of the downshift start tooth 59D1 with respect to the rotation center axis X.

As shown in FIG. 7A , the downshift recessed tooth 59D2 is disposed on the downstream side of the downshift start tooth 59D1 in the drive rotation direction RD of the seventh rear sprocket 47 and adjacent to the downshift start tooth 59D1. In the circumferential direction of the rotation center axis X, no other first sprocket 59 is arranged between the downshift start tooth 59D1 and the downshift recessed tooth 59D2.

As shown in FIG. 7A , the downshift recessed tooth 59D2 has a driving surface 59D2a and a non-driving surface 59D2b. The driving surface 59D2a is provided on the upstream side in the driving rotation direction RD of the seventh rear sprocket 47 with respect to the non-driving surface 59D2b. The non-driving surface 59D2b is provided on the opposite side of the driving surface 59D2a in the circumferential direction of the rotation center axis X.

As shown in FIG. 7A , the downshift recessed tooth 59D2 has a first tooth tip 59D2c. Downshift recessed tooth 59D2 has downshift recessed portion 71D2. The downshift recess 71D2 is provided on the first axial outer surface 47a of the downshift recess tooth 59D2. For example, the downshift recessed portion 71D2 is provided on the first axial outward side of the downshift recessed portion tooth 59D2 in such a manner that it is recessed from the first axial outer surface 47a toward the first axial inward surface 47b in the axial direction of the rotation center axis X. Side 47a.

Specifically, the downshift recessed portion 71D2 includes a first downshift recessed portion 71D2a and a second downshifted recessed portion 71D2b. Each of the downshift first recessed portion 71D2a and the downshift second recessed portion 71D2b is provided in the downshift in such a manner that it is recessed from the first axial outer side 47a toward the first axial inward side 47b in the axial direction of the rotation center axis X. The first axial outer surface 47a of the recessed tooth 59D2.

As shown in FIG. 7A , the downshift first recessed portion 71D2a and the downshift second recessed portion 71D2b are arranged side by side in the circumferential direction of the rotation center axis X. No other recessed portion is arranged between the first downshift recessed portion 71D2a and the second downshifted recessed portion 71D2b, and the first downshifted recessed portion 71D2a and the second downshifted recessed portion 71D2b are arranged adjacent to each other.

The downshift first recessed portion 71D2a reaches the first tooth tip 59D2c of the downshift recessed portion tooth 59D2. The downshift first recessed portion 71D2a reaches the driving surface 59D2a of the downshift recessed portion tooth 59D2.

As shown in FIG. 7A , the downshift first recessed portion 71D2a has a first recessed portion bottom surface 71D2c. The first axial depth is defined in the axial direction of the rotation center axis X from the first axial outer surface 47a of the first outer annular body 57 to the first recess bottom surface 71D2c. For example, the first axial depth is defined by the maximum distance from the first axial outer surface 47a of the first outer annular body 57 to the first recess bottom surface 71D2c in the axial direction of the rotation center axis X.

As shown in FIG. 7A , the second downshift recessed portion 71D2b does not reach the driving surface 59D2a of the downshift recessed portion tooth 59D2. The downshift second recessed portion 71D2b has a second recessed portion bottom surface 71D2d. The second axial depth is defined in the axial direction of the rotation center axis X from the first axial outer surface 47a of the first outer annular body 57 to the second recess bottom surface 71D2d. For example, the second axial depth is defined by the maximum distance from the first axial outer surface 47a of the first outer annular body 57 to the second recess bottom surface 71D2d in the axial direction of the rotation center axis X. The first axial depth is smaller than the second axial depth.

The downshift recessed tooth 59D3 is added on the downstream side of the downshift recessed tooth 59D2 in the drive rotation direction RD of the seventh rear sprocket 47 and is arranged adjacent to the downshift recessed tooth 59D2. In this embodiment, the downshift recessed teeth 59D2 and the additional downshift recessed teeth 59D3 are arranged side by side in the driving rotation direction RD of the seventh rear sprocket 47 .

The additional downshift recessed tooth 59D3 has a driving surface 59D3a and a non-driving surface 59D3b. The driving surface 59D3a is provided on the upstream side in the driving rotation direction RD of the seventh rear sprocket 47 with respect to the non-driving surface 59D3b. The non-driving surface 59D3b is provided on the opposite side of the driving surface 59D3a in the circumferential direction of the rotation center axis X.

As shown in FIG. 7A , the additional downshift recessed tooth 59D3 has a second tooth tip 59D3c. The additional downshift recessed portion tooth 59D3 has an additional downshift recessed portion 71D3. The additional downshift recess 71D3 is provided on the first axial outer surface 47a of the additional downshift recess tooth 59D3. For example, the additional downshift recess 71D3 is provided on the first shaft of the additional downshift recess tooth 59D3 in a manner that it is recessed from the first axial outer surface 47a toward the first axial inner surface 47b in the axial direction of the rotation center axis X. Outward side 47a.

The additional downshift recessed portion 71D3 reaches the second tooth tip 59D3c of the additional downshift recessed portion tooth 59D3. The additional downshift recess 71D3 reaches the driving surface 59D3a and the driven surface 59D3b of the additional downshift recessed tooth 59D3.

In order to smoothly promote the upshift operation, the above-mentioned seventh rear sprocket 47 is configured as follows. As shown in FIGS. 7A and 7B , the plurality of first sprocket teeth 59 include a plurality of upshift accelerating teeth 59U1, 59U2, and 59U3. The plurality of first sprocket teeth 59 may include additional upshift promoting teeth 59U0.

A plurality of upshift promoting teeth 59U1, 59U2, and 59U3 are configured to promote the upshifting action. The additional upshift promoting tooth 59U0 is configured to promote the upshifting action. The upshifting operation is an operation in which the drive chain 3 moves from the seventh rear sprocket 47 to the sixth rear sprocket 46 adjacent to the seventh rear sprocket 47 . That is, the upshift operation in this embodiment is an operation in which the drive chain 3 moves from the rear sprocket 47 to the small sprocket 46 adjacent to the rear sprocket 47 .

The plurality of upshift promoting teeth 59U1, 59U2, and 59U3 include an upshift shift tooth 59U1, an upshift start tooth 59U2, and an upshift recessed tooth 59U3. The additional upshift promoting teeth 59U0 include additional upshift shifting teeth 59U0.

As shown in FIG. 7A , the upshift gear 59U1 and the additional upshift gear 59U0 are configured to displace the drive chain 3 toward the sixth rear sprocket 46 during the upshift operation.

For example, during the upshift operation, when the inner link of the drive chain 3 is located at the additional upshift tooth 59U0 and the outer link of the drive chain 3 is located at the upshift tooth 59U1, the additional upshift tooth 59U0 and In the upshift shift tooth 59U1, the drive chain 3 is close to the sixth rear sprocket 46 side.

As shown in FIG. 7B , the upshift tooth 59U1 has a second axial recessed portion 59U1a. The second axial recess 59U1a is provided on the first axial inner surface 47b of the upshift tooth 59U1. For example, the second axial recess 59U1a is provided in the first upshift tooth 59U1 in a manner that it is recessed from the first axial inner side 47b toward the first axial outer side 47a in the axial direction of the rotation center axis X. Axial medial side 47b. The second axial recess 59U1a is arranged at least on the tooth tip 59U1b of the upshift tooth 59U1.

The upshift tooth 59U0 is added on the downstream side of the upshift tooth 59U1 in the drive rotation direction RD, and is arranged adjacent to the upshift tooth 59U1. The additional upshift gear 59U0 may also be a common driving gear that does not have the function of the upshift gear.

The additional upshift tooth 59U0 has a third axial recess 59U0a. The third axial recess 59U0a is provided on the first axial inner surface 47b of the additional upshift tooth 59U0. The third axial recess 59U0a is provided on the first shaft of the additional upshift gear 59U0 so as to be recessed from the first axial inner side 47b toward the first axial outer side 47a in the axial direction of the rotation center axis X. Inward side 47b. The third axial recess 59U0a is arranged at least on the tooth tip 59U0b of the additional upshift tooth 59U0.

The second axial recessed portion 59U1a and the third axial recessed portion 59U0a may be a recessed portion or an inclined portion. The second axial recess 59U1a may also extend radially inward from the tooth tip 59U1b of the upshift tooth 59U1 on the rotation center axis X. The third axial recess 59U0a may also extend radially inward from the tooth tip 59U0b of the additional upshift tooth 59U0 on the rotation center axis X.

As shown in FIG. 7A , the upshift start tooth 59U2 is configured to be disengaged from the drive chain 3 first during the upshift operation. For example, during the upshift operation, when the inner link of the drive chain 3 is located at the upshift start tooth 59U2, the drive chain 3 begins to disengage from the upshift start tooth 59U2.

The upshift start tooth 59U2 is located upstream of the upshift tooth 59U1 in the drive rotation direction RD of the seventh rear sprocket 47 and is arranged adjacent to the upshift tooth 59U1.

For example, in the circumferential direction of the rotation center axis The upstream side of the upshift gear 59U1 in the drive rotation direction RD is arranged adjacent to the upshift gear 59U1.

As shown in FIG. 7A , the upshift start tooth 59U2 has an upshift first recessed portion 59U2a. The first upshift recess 59U2a is provided on the first axial outer surface 47a of the upshift start tooth 59U2. For example, the first upshift recess 59U2a is provided on the first shaft of the upshift start tooth 59U2 in a manner that it is recessed from the first axial outer surface 47a toward the first axial inner surface 47b in the axial direction of the rotation center axis X. Outward side 47a.

As shown in FIG. 7A , the upshift recessed tooth 59U3 is used to assist the disengagement of the drive chain 3 from the upshift start tooth 59U2 during the upshift operation. For example, when the inner link of the drive chain 3 is separated from the upshift start tooth 59U2, the upshift recessed tooth 59U3 is configured such that the outer link of the drive chain 3 does not engage with the upshift recessed tooth 59U3. .

The upshift recessed tooth 59U3 is disposed on the upstream side of the upshift start tooth 59U2 in the drive rotation direction RD and adjacent to the upshift start tooth 59U2. For example, in the circumferential direction of the rotation center axis The upstream side of the shift start tooth 59U2 is arranged adjacent to the upshift start tooth 59U2.

As shown in FIG. 7A , the upshift recessed portion tooth 59U3 has a second upshift recessed portion 59U3a. The upshift recessed tooth 59U3 is provided on the first axial outer surface 47a of the upshift recessed tooth 59U3. For example, the second upshift recessed portion 59U3a is provided on the first shaft of the upshift recessed tooth 59U3 in such a manner that it is recessed from the first axial outer side 47a toward the first axial inward side 47b in the axial direction of the rotation center axis X. Outward side 47a.

·8th rear sprocket As shown in FIGS. 5 , 8A and 8B , the eighth rear sprocket 48 has a rotation center axis X, a second axial outer surface 48 a and a second axial inner surface 48 b. The rotation center axis X is concentric with the rotation center axis of the rear sprocket assembly 27 described above. As shown in FIGS. 5 and 8A , the second axial outer surface 48 a forms an outer surface of the eighth rear sprocket 48 in the axial direction of the rotation center axis X.

As shown in FIGS. 5 and 8B , the second axial inner surface 48b forms the inner surface of the eighth rear sprocket 48 in the axial direction of the rotation center axis X. The second axial inner surface 48b is provided on the opposite side to the second axial outer surface 48a in the axial direction of the rotation center axis X. The second axial inner side surface 48b is configured to face the axial center plane P shown in FIG. 2 in the axial direction of the rotation center axis X when mounted on the bicycle 1 .

As shown in FIGS. 8A and 8B , the eighth rear sprocket 48 includes a first outer annular body 58 , a plurality of second sprocket teeth 60 , a second inner annular body 62 , and at least one second connecting arm 64 . The second outer annular body 58, the plurality of second sprocket teeth 60, the second inner annular body 62, and at least one second connecting arm 64 are formed as a single integral member.

The plurality of second sprocket teeth 60 extend radially outward from the outer peripheral portion 58a of the second outer annular body 58 in the radial direction of the rotation center axis X. In this embodiment, the total number of the plurality of second sprocket teeth 60 is 30.

As shown in FIG. 6C , each of the plurality of second sprocket teeth 60 has a second maximum radial length L3 and a second maximum axial length L4. The second maximum radial length L3 is defined in the radial direction of the rotation center axis X. For example, the second maximum radial length L3 is the length from the outer peripheral portion 58a of the second outer annular body 58 to the tooth tips 60a of the plurality of second sprocket teeth 60 in the radial direction of the rotation center axis X. The outer peripheral portion 58a of the second outer annular body 58 is defined by the tooth base circles 58b of the plurality of second sprocket teeth 60.

The second maximum axial length L4 is defined in the axial direction of the rotation center axis X. For example, the second maximum axial length L4 is the axial direction of the rotation center axis The maximum length between sides 48b.

The second maximum axial length L4 is the maximum length between the second axial outer surface 48a and the second axial inner surface 48b at the position of the outer peripheral portion 58a of the second outer annular body 58. The second maximum axial length L4 is shorter than the second maximum radial length L3.

As shown in FIG. 4 , the second inner annular body 62 is configured to be connected to the rear wheel housing assembly 19 in a torque-transmissible manner when the eighth rear sprocket 48 is mounted on the rear wheel housing assembly 19 . Sprocket support 19a.

As shown in FIG. 5 , FIG. 8A and FIG. 8B , the second inner annular body 62 has a second spline hole 62 a. The second spline hole 62a forms the inner peripheral surface of the second inner annular body 62. As shown in FIG. 4 , the second spline hole 62 a is configured to engage with the sprocket support 19 a of the rear wheel housing assembly 19 when the eighth rear sprocket 48 is mounted on the rear wheel housing assembly 19 . For example, the sprocket support 19a is a cylindrical spline shaft.

As shown in FIGS. 8A and 8B , at least one second connecting arm 64 extends in the radial direction between the second outer annular body 58 and the second inner annular body 62 . At least one second connecting arm 64 is formed in a tapered shape from the third radial position RP3 toward the fourth radial position RP4. For example, at least one second connecting arm 64 is formed in a tapered shape such that the third circumferential width W3 of the second connecting arm 64 gradually becomes smaller from the third radial position RP3 toward the fourth radial position RP4. Details of the third circumferential width W3 are described below.

As shown in FIGS. 8A and 8B , at least one second connecting arm 64 has a second radially outer half section 66 and a second radially inner half section 68 . At least one second connecting arm 64 has a second rivet hole 70 . At least one second connecting arm 64 has a third rivet hole 72 . The first rivet 53a shown in FIG. 4 is inserted into the second rivet hole 70. The second rivet 53b shown in FIG. 4 is inserted into the third rivet hole 72.

For example, at least one second connecting arm 64 includes a plurality of second connecting arms 64 . Preferably, the total number of the plurality of second connecting arms 64 is four or more. In the embodiment, the total number of the plurality of second connecting arms 64 is seven.

As shown in FIGS. 8A and 8B , the second radially outer half section 66 is provided between the second outer annular body 58 and the second radially inner half section 68 in the radial direction of the rotation center axis X. The second radially outer half section 66 is integrally formed with the second outer annular body 58 and the second radially inner half section 68 .

The first radially outer half section 65 has a third circumferential width W3. The third circumferential width W3 is defined by the third radial position RP3 of the rotation center axis X. The third circumferential width W3 is the length of the arc extending in the circumferential direction of the rotation center axis X at the third radial position RP3 of the rotation center axis X. For example, the third circumferential width W3 is 11 mm or more. The third circumferential width W3 is 20 mm or less. That is, the third circumferential width W3 is 11 mm or more and 20 mm or less.

As shown in FIGS. 8A and 8B , the second radially inner half section 68 is located radially inward from the second radially outer half section 66 in the radial direction of the rotation center axis X. The second radially inner half section 68 is provided between the second radially outer half section 66 and the second inner annular body 62 in the radial direction of the rotation center axis X. The second radially inner half section 68 is integrally formed with the second radially outer half section 66 and the second radially inner annular body 62 .

The second radially inner half section 68 has a fourth circumferential width W4. The fourth circumferential width W4 is defined by the fourth radial position RP4 of the rotation center axis X. The fourth circumferential width W4 is the length of the arc extending in the circumferential direction of the rotation center axis X at the fourth radial position RP4 of the rotation center axis X.

For example, the fourth circumferential width W4 is smaller than the third circumferential width W3. The fourth circumferential width W4 is 5 mm or more. The fourth circumferential width W4 is 10 mm or less. That is, the fourth circumferential width W4 is 5 mm or more and 10 mm or less.

As shown in FIGS. 8A and 8B , the second rivet hole 70 is provided at the third radial position RP3 of the third circumferential width W3. The second rivet hole 70 has a hole diameter D2. For example, the ratio W3/D2 of the third circumferential width W3 to the hole diameter D2 is 2.5 or more. The ratio W3/D2 of the third circumferential width W3 to the hole diameter D2 is 5.0 or less.

That is, the ratio W3/D2 of the third circumferential width W3 to the hole diameter D2 is 2.5 or more and 5.0 or less. In this embodiment, the third circumferential width W3 is 12.6 mm, and the hole diameter is 4.23. In this case, the ratio W3/D2 of the third circumferential width W3 to the hole diameter D2 is 3.0.

In order to smoothly promote the downshift operation, the eighth rear sprocket 48 is configured as follows. As shown in FIGS. 9A and 9B , the plurality of second sprocket teeth 60 include a plurality of downshift accelerating teeth 60D1 and 60D2. The plurality of second sprocket teeth 60 may further include additional downshift accelerating teeth 60D3.

The plurality of downshift promoting teeth 60D1, 60D2 and the additional downshift promoting teeth 60D3 are configured to promote the movement of the drive chain 3 from the seventh rear sprocket 47 adjacent to the eighth rear sprocket 48 to the lower position of the eighth rear sprocket 48. file action. That is, the downshift operation in this embodiment is an operation in which the drive chain 3 moves from the small sprocket 47 adjacent to the rear sprocket 48 to the rear sprocket 48 .

9A and 9B show the structure of a plurality of downshift promoting teeth 60D1, 60D2 and an additional downshift promoting tooth 60D3. The symbol "59D" in Fig. 7A and Fig. 7B is replaced with the symbol "60D", and the symbol " 71D" is replaced by the symbol "73D".

That is, the plurality of downshift accelerating teeth 60D1, 60D2 and the additional downshift accelerating tooth 60D3 are substantially the same as the plurality of downshift accelerating teeth 59D1, 59D2 and the additional downshift accelerating tooth 59D3 of the seventh rear sprocket 47.

For example, in the above description of the structure of the downshift operation of the seventh rear sprocket 47, the main structure of the seventh rear sprocket 47 is understood to be the main structure of the eighth rear sprocket 48, and the seventh rear sprocket 47 is The symbol "59D" of 47 is replaced with the symbol "60D", and the symbol "71D" of the seventh rear sprocket 47 is replaced with the symbol "73D", so that the composition and addition of the plurality of downshift accelerating teeth 60D1 and 60D2 can be understood Downshifting gear 60D3 is formed. Therefore, detailed description of the plurality of downshift promoting teeth 60D1 and 60D2 and the additional downshift promoting teeth 60D3 will be omitted below. The description omitted here follows the description of the structure of the downshift operation of the seventh rear sprocket 47.

The plurality of downshift accelerating teeth 60D1 and 60D2 include a downshift start tooth 60D1 and a downshift recessed tooth 60D2. The downshift start tooth 60D1 has a driving surface 60D1a and a non-driving surface 60D1b. The downshift start tooth 60D1 has a first axial recessed portion 60D1e.

The downshift recessed tooth 60D2 has a driving surface 60D2a and a non-driving surface 60D2b. The downshift recessed tooth 60D2 has a first tooth tip 60D2c. Downshift recessed tooth 60D2 has downshift recessed portion 73D2. The downshift recess 73D2 includes a first downshift recess 73D2a and a second downshift recess 73D2b.

The additional downshift accelerating teeth 60D3 include additional downshift recessed teeth 60D3. The additional downshift recessed tooth 60D3 has a driving surface 60D3a and a non-driving surface 60D3b. The additional downshift recessed tooth 60D3 has a second tooth tip 60D3c. The additional downshift recessed portion tooth 60D3 has an additional downshift recessed portion 73D3.

In order to smoothly promote the upshift operation, the eighth rear sprocket 48 is configured as follows. As shown in FIGS. 9A and 9B , the plurality of second sprocket teeth 60 include a plurality of upshift accelerating teeth 60U1, 60U2, and 60U3. The plurality of second sprocket teeth 60 may include additional upshift promoting teeth 60U0.

A plurality of upshift promoting teeth 60U1, 60U2, and 60U3 are configured to promote the upshifting action. The additional upshift promoting tooth 60U0 is configured to promote the upshifting action. The upshifting operation is an operation in which the drive chain 3 moves from the eighth rear sprocket 48 to the seventh rear sprocket 47 adjacent to the eighth rear sprocket 48 . That is, the upshift operation in this embodiment is an operation in which the drive chain 3 moves from the rear sprocket 48 to the small sprocket 47 adjacent to the rear sprocket 48 .

9A and 9B show the structure of a plurality of upshift promoting teeth 60U1, 60U2, and 60U3 and the structure of an additional upshift promoting tooth 60U0. The symbol "59U" in Fig. 7A and Fig. 7B is replaced with the symbol "60U".

That is, the plurality of upshift accelerating teeth 60U1, 60U2, 60U3, and the additional upshift accelerating tooth 60U0 are substantially the same as the plurality of upshift accelerating teeth 59U0, 59U1, 59U2, and 59U3 of the seventh rear sprocket 47.

For example, in the above description of the structure of the upshift operation of the seventh rear sprocket 47, the main structure of the seventh rear sprocket 47 is understood to be the main structure of the eighth rear sprocket 48, and the seventh rear sprocket 47 is The symbol "59U" of 47 is replaced with the symbol "60U", so that the composition of a plurality of upshift accelerating gears 60U1, 60U2, 60U3 and the additional upshift accelerating gear 60U0 can be understood. Therefore, detailed descriptions of the plurality of upshift promoting teeth 60U1, 60U2, and 60U3 and the additional downshift promoting teeth 60U0 are omitted here. The description omitted here is based on the description of the structure of the upshift operation of the seventh rear sprocket 47.

The plurality of upshift promoting teeth 60U1, 60U2, 60U3 and the additional upshift promoting tooth 60U0 include an upshift shift tooth 60U1, an upshift starting tooth 60U2, an upshift recessed tooth 60U3 and an additional upshift promoting tooth 60U0. The upshift tooth 60U1 has a second axial recess 60U1a. The upshift start tooth 60U2 has an upshift first recessed portion 60U2a. The upshift recessed portion tooth 60U3 has a second upshift recessed portion 60U3a. The additional upshift tooth 60U0 has a third axial recess 60U0a.

1:Bicycle 3: Drive chain 5: Frame 7: handle 9:Front wheel 9a: Front tire 11:Rear wheel 11a: rear tire 13:Speed operating device 15:Drive Department 17:Front fork 18: Front wheel housing assembly 19:Rear wheel housing assembly 19a: Sprocket support 21:Front derailleur 23:Rear derailleur 27:Rear sprocket assembly 28a~28f: spacer 29:Crank assembly 31:Crank arm 33: Front sprocket assembly 41~51: Rear sprocket (1st to 11th rear sprocket) 47a: 1st axis outward side 47b: The inner side of the first axis 48a: 2nd axis outward side 48b: The inner side of the second axis 53a: No. 1 rivet 53b: 2nd rivet 53c: 3rd rivet 53d: No. 4 rivet 53e:Connecting components 57: 1st outer annular body 57a: Peripheral part 57b:Tooth base circle 58: 2nd outer annular body 58a: Peripheral part 58b:Tooth base circle 59: 1st sprocket tooth 59a:Tooth tip 59D1: Downshift promotion tooth, downshift start tooth 59D1a: driving surface 59D1b: Non-driving surface 59D1c:Tooth tip 59D1d:Tooth tip 59D1e: 1st axial recess 59D1f:Tooth tip 59D2: Downshift promotion teeth, downshift concave teeth 59D2a: Driving surface 59D2b: Non-driving surface 59D2c: 1st tooth tip 59D3: Additional downshift accelerating teeth and additional downshift concave teeth 59D3a: Driving surface 59D3b: Non-driving surface 59D3c: 2nd tooth tip 59U0: Upshift promotion gear, additional upshift shift gear 59U0a: 3rd axial recess 59U0b:Tooth tip 59U1: Upshift promotion gear, upshift shift gear 59U1a: 2nd axial recess 59U1b:Tooth tip 59U2: Upshift promotion tooth, upshift start tooth 59U2a: Upshift first recess 59U3: Upshift promotion teeth, upshift concave teeth 59U3a: Upshift second recess 60: 2nd sprocket teeth 60a:Tooth tip 60D1: Downshift promotion tooth, downshift start tooth 60D1a: driving surface 60D1b: non-driving surface 60D1e: 1st axial recess 60D2: Downshift promotion teeth, downshift concave teeth 60D2a: driving surface 60D2b: Non-driving surface 60D2c: 1st tooth tip 60D3: Additional downshift promoting teeth and additional downshift concave teeth 60D3a: driving surface 60D3b: non-driving surface 60D3c: 2nd tooth tip 60U0: Upshift promotion gear, additional upshift shift gear 60U0a: 3rd axial recess 60U1: Upshift promotion gear, upshift shift gear 60U1a: 2nd axial recess 60U2: Upshift promotion tooth, upshift start tooth 60U2a: Upshift first recess 60U3: Upshift promotion teeth, upshift concave teeth 60U3a: Upshift second recess 61: 1st inner annular body 61a: 1st spline hole 62: 2nd inner annular body 62a: 2nd spline hole 63: 1st connecting arm 64: 2nd connecting arm 65: 1st radially outer half section 66: 2nd radially outer half section 67: 1st radial inner half section 68: 2nd radial inner half section 69: 1st rivet hole 70: 2nd rivet hole 71D2: Downshift recess 71D2a: Bottom of the first recess 71D2b: Downshift 2nd recess 71D2c: Bottom of the first concave part 71D2d: Bottom of the second concave portion 71D3: Downshift recess 71D3a: Bottom surface of the second recess 72: 3rd rivet hole 73D2: Downshift 1st recess 73D2a: Downshift 1st recess 73D2b: Downshift 2nd recess 73D3: Downshift second recess D1:Aperture D2:Aperture L1: The first maximum radial length L2: 1st maximum axial length L3: The second maximum radial length L4: The second maximum axial length P: axial center plane RD: Drive rotation direction RP1: 1st radial position RP2: 2nd radial position RP3: 3rd radial position RP4: 4th radial position W1: 1st circumferential width W2: 2nd circumferential width W3: 3rd circumferential width W4: 4th circumferential width X: rotation center axis

Figure 1 is a side view of a bicycle according to an embodiment of the present invention. Figure 2 is a schematic diagram of a bicycle viewed from above. Figure 3 is a perspective view of the rear sprocket assembly. Figure 4 is a cross-sectional view of the rear sprocket assembly. Figure 5 is a perspective view of the seventh and eighth sprockets. Figure 6A is the front view of the seventh sprocket. Figure 6B is a rear view of the seventh sprocket. Figure 6C is a partial enlarged cross-sectional view of the tooth tips of the seventh and eighth sprockets. Figure 7A is a front view of the seventh sprocket for explaining the shifting action. FIG. 7B is a rear view of the seventh sprocket for explaining the shifting operation. Figure 8A is the front view of the eighth sprocket. Figure 8B is a rear view of the eighth sprocket. Figure 9A is a front view of the eighth sprocket for explaining the shifting action. FIG. 9B is a rear view of the eighth sprocket for explaining the shifting operation.

47: 7th rear sprocket

47a: 1st axis outward side

57: 1st outer annular body

57a: Peripheral part

57b:Tooth base circle

59: 1st sprocket tooth

61: 1st inner annular body

61a: 1st spline hole

63: 1st connecting arm

65: 1st radially outer half section

67: 1st radial inner half section

69: 1st rivet hole

D1:Aperture

RP1: 1st radial position

RP2: 2nd radial position

W1: 1st circumferential width

W2: 2nd circumferential width

X: rotation center axis

Claims (20)

A rear sprocket for human-driven vehicles, which can be used for human-driven vehicles with an axial center plane, and has: a rotation center axis; an axial outer side; and an axial inner side, which is on the axis of the above-mentioned rotation center axis upward, is provided on the opposite side of the above-mentioned axial outer surface, and is configured to face the above-mentioned axial center surface in the above-mentioned axial direction when installed on the above-mentioned human-driven vehicle; and the rear sprocket has: lateral annulus; A plurality of sprocket teeth, which are equal to the radial direction of the above-mentioned rotation center axis and extend radially outward from the outer peripheral surface of the above-mentioned outer annular body; The inner annular body is configured to be connected to the sprocket supporting body of the wheel housing assembly in a torque-transmissible manner when the rear sprocket is mounted on the wheel housing assembly; and At least one connecting arm has: a radially outer half section extending in the above-mentioned radial direction between the above-mentioned outer annular body and the above-mentioned inner annular body; and a radially inner half section, which extends in the above-mentioned radial direction. Located at a position from the above-mentioned radially outer half toward the radially inner side; and Each of the plurality of sprocket teeth has a maximum radial length defined in the above-mentioned radial direction, and a maximum axial length defined in the above-mentioned axial direction and shorter than the above-mentioned maximum radial length, The radially outer half section has a first circumferential width defined by the first radial position of the rotation center axis, The above-mentioned radially inner half section has a second circumferential width defined by the second radial position of the above-mentioned rotation center axis and smaller than the above-mentioned first circumferential width, The at least one connecting arm is formed in a tapered shape from the first radial position toward the second radial position, The outer annular body, the plurality of sprocket teeth, the inner annular body, and the at least one connecting arm are formed as a single integral member. For example, the rear sprocket for a human-powered vehicle in claim 1, wherein The above-mentioned at least one connecting arm includes a plurality of connecting arms. For example, the rear sprocket for a human-powered vehicle in claim 2, wherein The total number of the plurality of connecting arms is 4 or more. For example, the rear sprocket for a human-driven vehicle according to any one of claims 1 to 3, wherein The at least one connecting arm has a rivet hole provided at the first radial position of the first circumferential width. For example, the rear sprocket for a human-powered vehicle in claim 4, wherein The above-mentioned rivet holes have an aperture, The ratio of the width in the first circumferential direction to the diameter of the hole is 2.5 or more. For example, the rear sprocket for a human-driven vehicle according to any one of claims 1 to 3, wherein The inner annular body has a spline portion, and the spline portion is configured to engage with the sprocket support body of the wheel housing assembly in the assembled state. For example, the rear sprocket for a human-driven vehicle according to any one of claims 1 to 3, wherein The above-mentioned first circumferential width is 11 mm or more. For example, the rear sprocket for a human-driven vehicle according to any one of claims 1 to 3, wherein The above-mentioned first circumferential width is 20 mm or less. For example, the rear sprocket for a human-driven vehicle according to any one of claims 1 to 3, wherein The above-mentioned second circumferential width is 5 mm or more. For example, the rear sprocket for a human-driven vehicle according to any one of claims 1 to 3, wherein The above-mentioned second circumferential width is 10 mm or less. For example, the rear sprocket for a human-driven vehicle according to any one of claims 1 to 3, wherein The plurality of sprocket teeth include a plurality of downshift promoting teeth, which are configured to promote the downshifting action of the drive chain from the small sprocket adjacent to the rear sprocket to the rear sprocket. The plurality of downshift promoting teeth mentioned above include: The downshift start tooth is configured to engage with the drive chain first during the downshift action; and Downshift recessed teeth arranged adjacent to the downshift start tooth on the downstream side of the downshift start tooth in the driving rotation direction of the rear sprocket; In the circumferential direction of the above-mentioned rotation center axis, no other sprocket teeth are arranged between the above-mentioned downshift start teeth and the above-mentioned downshift recess teeth. The downshift recessed tooth has a downshift recess, and the downshift recess is provided on the axial outer surface of the downshift recessed tooth in a manner that it is recessed from the axial outer surface toward the axial inward surface in the axial direction. For example, the rear sprocket for a human-powered vehicle in claim 11, wherein A first axial recessed portion is provided on the above-mentioned axially inner surface of the above-mentioned downshift start tooth in the above-mentioned axial direction in such a manner that it is recessed from the above-mentioned axial inner surface toward the above-mentioned axial outer surface, The first axial recess is disposed at least on a tooth tip of the downshift starting tooth. For example, the rear sprocket for a human-powered vehicle in claim 11, wherein The above-mentioned downshift recess has a first downshift recess and a second downshift recess, and each of the above-mentioned first downshift recess and the above-mentioned downshift second recess is in the above-mentioned axial direction, from the above-mentioned axial outer surface to the above-mentioned axial inner surface. The form of recess is provided on the above-mentioned axial outer surface of the above-mentioned downshift recessed tooth, The above-mentioned first recessed portion for downshifting has a first recessed portion bottom surface, The above-mentioned second recessed portion for downshifting has a second recessed portion bottom surface, The first axial depth is defined in the above-mentioned axial direction from the above-mentioned axial outer surface of the above-mentioned outer annular body to the above-mentioned first recess bottom surface, The second axial depth is defined in the above-mentioned axial direction from the above-mentioned axial outer surface of the above-mentioned outer annular body to the above-mentioned second recess bottom surface, The first axial depth is smaller than the second axial depth. For example, the rear sprocket for a human-powered vehicle in claim 13, wherein The above-mentioned downshift recessed tooth has a first tooth tip, The first downshift recessed portion reaches the first tooth tip of the downshift recessed portion tooth. For example, the rear sprocket for a human-powered vehicle in claim 13, wherein The downshift recessed tooth has a driving surface and a non-driving surface provided on the opposite side of the driving surface in the circumferential direction, The first downshift recessed portion reaches the driving surface of the downshift recessed portion tooth. For example, the rear sprocket for a human-powered vehicle in claim 15, wherein The said downshift 2nd recessed part does not reach the said driving surface of the said downshift recessed part tooth. For example, the rear sprocket for a human-powered vehicle in claim 13, wherein No other recessed portion is arranged between the first downshift recessed portion and the second downshifted recessed portion, and the first downshifted recessed portion and the second downshifted recessed portion are arranged adjacent to each other. For example, the rear sprocket for a human-driven vehicle according to any one of claims 1 to 3, wherein The plurality of sprocket teeth include a plurality of upshift promoting teeth, which are configured to promote the upshifting action of the drive chain moving from the rear sprocket to the small sprocket adjacent to the rear sprocket. For example, the rear sprocket for a human-powered vehicle in claim 18, wherein The above-mentioned plurality of upshift promoting teeth include: The upshift shift tooth is configured to shift the drive chain toward the small sprocket during the upshift operation; The upshift start tooth is configured to be the first to disengage from the drive chain during the above-mentioned upshift action; and Upshift recessed teeth; and The above-mentioned upshift start tooth has a first upshift recess, which is provided on the above-mentioned axially outer surface of the above-mentioned upshift start tooth in the above-mentioned axial direction in a manner that it is recessed from the above-mentioned axially outer surface toward the above-mentioned axially inner surface, In the circumferential direction of the rotation center axis, no other sprocket teeth are arranged between the upshift start teeth and the upshift shift teeth, and the upshift start teeth are located above the rear sprocket in the driving rotation direction. The upstream side of the upshift gear is arranged adjacent to the above-mentioned upshift gear, The above-mentioned upshift recessed tooth has a second upshift recess, which is provided on the above-mentioned axially outer surface of the above-mentioned upshift recessed tooth in the above-mentioned axial direction in such a manner that it is recessed from the above-mentioned axial outer surface toward the above-mentioned axially inner surface, In the above-mentioned circumferential direction, no other sprocket teeth are arranged between the above-mentioned upshift recessed teeth and the above-mentioned upshift start teeth, and the above-mentioned upshift recessed teeth are on the upstream side of the above-mentioned upshift start teeth in the above-mentioned driving rotation direction, and the above-mentioned The upshift start teeth are arranged adjacently. For example, the rear sprocket for a human-powered vehicle in claim 19, wherein The above-mentioned second axial recessed portion is provided on the above-mentioned axially inner surface of the above-mentioned upshift shift tooth in the above-mentioned axial direction in a manner that it is recessed from the above-mentioned axial inner surface toward the above-mentioned axial outer surface, The second axial recess is disposed at least on the tooth tip of the upshift tooth.