JP2023064426A - rear sprocket - Google Patents

Abstract

To provide a rear sprocket with high strength and rigidity.SOLUTION: A rear sprocket comprises: a sprocket body; a plurality of sprocket teeth which extend to a radial direction outer side from an outer peripheral part of the sprocket body; and at least one first axial projection which is formed on a radial direction inner peripheral part so as to become a single member integrated with the sprocket body. At least one first axial projection has: a proximal end which is integrally connected to the sprocket body; and a free distal end which is so configured as not to contact another rear sprocket of a rear sprocket assembly in the assembly state of the rear sprocket assembly. At least one first axial projection extends in an axial direction from an axial inward face in the radial direction inner peripheral part so as to separate from an axial outward face. At least one first axial projection continuously extends over at least 1/6 of the whole circumference of the radial direction inner peripheral part in a circumferential direction concerning a rotation center axis.SELECTED DRAWING: Figure 5

Description

The present disclosure relates to rear sprockets.

For example, in FIG. 20 of Patent Document 1, rear sprockets 334, 336, 338, and 340 attached to sprocket carriers 339 and 341, rear sprocket 32 attached to rear sprocket 334, and rear sprocket 30 attached to rear sprocket 32 , is disclosed.

U.S. Patent Application Publication No. 2008/0004143

The rear sprockets 30, 32, 334, 336, 338, and 340 disclosed in Patent Document 1 are arranged such that the inner peripheral edge of the rear sprocket is radially separated from the sprocket support of the rear hub assembly when the rear sprocket assembly is assembled. Attached to a carrier or other sprocket.

Rear sprockets such as the rear sprockets 30, 32, 334, 336, 338, and 340 of Patent Document 1 tend to decrease in strength and rigidity when the thickness of the rear sprocket is reduced for the purpose of weight reduction, for example. rice field.

One object of the present disclosure is to provide a strong and stiff rear sprocket.

A rear sprocket according to the first aspect of the present disclosure is a rear sprocket attachable to a rear hub assembly for a manpowered vehicle, the rear sprocket having an axially outward surface and an axial an axially inwardly facing surface provided opposite the outwardly facing surface and configured to be spaced apart from a sprocket support of the rear hub assembly in an installed condition in which a rear sprocket assembly including the rear sprocket is attached to the rear hub assembly; and at least one attachment portion configured to attach to one of a sprocket carrier of the rear sprocket assembly and another rear sprocket of the rear sprocket assembly; The inward surface is configured to face the axial center surface of the manpowered vehicle in the attached state in the axial direction, and the outer peripheral portion of the sprocket body in the radial direction about the rotation center axis. a plurality of sprocket teeth extending radially outwardly from the sprocket body; , the at least one first axial projection has a proximal end integrally connected to the sprocket body and a rear sprocket so as not to contact another rear sprocket of the rear sprocket assembly in the assembled state of the rear sprocket assembly; and a free distal end configured so that the at least one first axial projection extends from the axially inwardly facing surface at the radially inner circumference away from the axially outwardly facing surface. Extending in the axial direction, the at least one first axial projection extends continuously over at least one-sixth of the entire circumference of the radially inner circumference in a circumferential direction about the central axis of rotation.
According to the rear sprocket on the first side, the first axial protrusion formed on the radially inner peripheral portion so as to form a single member integrated with the sprocket body functions as a reinforcing rib. Also, since the first axial projection extends axially from the axially inward surface away from the axially outwardly facing surface, it does not interfere with the chain engaged with the small sprocket adjacent to the rear sprocket. Therefore, the strength and rigidity of the rear sprocket can be effectively improved without interfering with the chain engaged with the adjacent small sprocket.

A second side rear sprocket according to the first side of the present disclosure is configured to be arranged axially outward from a largest sprocket of the rear sprocket assembly in the axial direction in the assembled state of the rear sprocket assembly.
According to the rear sprocket on the second side, it is possible to effectively improve the strength and rigidity of the rear sprocket without interfering with the chain engaged with the adjacent small sprocket.

In the rear sprocket of the third aspect according to the first aspect or the second aspect of the present disclosure, the at least one first axial protrusion extends in the circumferential direction at least a quarter of the total circumference of the radially inner circumference. extends continuously over one of the
According to the rear sprocket on the third side, since the first axial protrusion extends longer, the strength and rigidity of the rear sprocket can be further improved.

In the fourth aspect rear sprocket according to the third aspect of the present disclosure, said at least one first axial projection extends continuously in said circumferential direction over at least half of the total circumference of said radially inner circumference.
According to the rear sprocket on the fourth side, since the first axial protrusion extends longer, the strength and rigidity of the rear sprocket can be further improved.

In the fifth aspect rear sprocket according to the fourth aspect of the present disclosure, the at least one first axial protrusion extends continuously around the radially inner circumference in the circumferential direction.
According to the rear sprocket on the fifth side surface, the first axial protrusion extends longer, so the strength and rigidity of the rear sprocket can be further improved.

The sixth aspect of the rear sprocket according to the fifth aspect of the present disclosure, wherein said at least one first axial projection is non-circular.
According to the sixth side rear sprocket, the strength and rigidity of the rear sprocket can be further improved.

The seventh aspect rear sprocket according to any one of the first through sixth aspects of the present disclosure includes at least one second axial projection extending around at least one lightening hole formed in the sprocket body. Prepare more.
According to the seventh side rear sprocket, the second axial protrusion extending around the lightening hole also functions as a reinforcing rib. Therefore, it is possible to achieve both weight reduction of the rear sprocket and improvement of the strength and rigidity of the rear sprocket.

The eighth aspect rear sprocket according to any one of the first through seventh aspects of the present disclosure, wherein the plurality of sprocket teeth comprises at least one downshift-facilitating tooth and at least one upshift-facilitating tooth. At least one.
According to the eighth side rear sprocket, since the rear sprocket is excellent in strength and rigidity, a stable and smooth shift operation can be realized.

In the ninth aspect rear sprocket according to the eighth aspect of the present disclosure, the at least one first axial protrusion comprises, when viewed in the axial direction, in the circumferential direction, the at least one downshift-promoting tooth; and Overlaps said at least one of said at least one upshift promoting tooth.
According to the rear sprocket on the ninth side surface, at least one of the downshift promoting tooth and the upshift promoting tooth for promoting speed change is positioned in the portion where the strength and rigidity are increased by the first axial protrusion. , a more stable and smooth shift operation can be realized.

A rear sprocket according to a tenth aspect of the present disclosure is a rear sprocket attachable to a rear hub assembly for a manpowered vehicle, the rear sprocket having an axially outward surface and an axial direction relative to a rotation center axis of the rear sprocket. an axially inwardly facing surface opposite the outwardly facing surface; and at least one lightening hole, wherein the axially inwardly facing surface is configured such that a rear sprocket assembly including the rear sprocket is attached to the rear hub assembly. a sprocket body configured to face the axial center plane of the manpowered vehicle in the attached state in the axial direction; a plurality of outwardly extending sprocket teeth and at least one axial projection formed about the at least one lightening hole so as to be a unitary member integral with the sprocket body. .
According to the tenth side rear sprocket, the rear sprocket is lightened by the lightening hole, and the axial projection functions as a reinforcing rib. Therefore, it is possible to effectively improve the strength and rigidity of the rear sprocket while reducing the weight.

In the rear sprocket of the eleventh aspect according to the tenth aspect of the present disclosure, the at least one axial protrusion extends axially from the axially inwardly facing surface away from the axially outwardly facing surface.
According to the rear sprocket on the eleventh side surface, the strength and rigidity of the rear sprocket can be effectively improved without interfering with the chain engaged with the small sprocket adjacent to the rear sprocket.

In the rear sprocket of the twelfth aspect according to the tenth or eleventh aspect of the present disclosure, the at least one axial protrusion includes a proximal end integrally connected to the sprocket body and the rear sprocket assembly. a free distal end configured not to contact another rear sprocket of the rear sprocket assembly in its assembled state.
According to the rear sprocket on the twelfth side, it is possible to effectively improve the strength and rigidity of the rear sprocket while reducing the weight.

In the rear sprocket of the thirteenth aspect according to any one of the tenth through twelfth aspects of the present disclosure, said at least one axial protrusion completely surrounds said at least one lightening hole.
According to the rear sprocket on the thirteenth side surface, the axially protruding portion reinforces the entire periphery of the weight reduction hole, so that the strength and rigidity of the rear sprocket can be effectively improved while reducing weight. .

According to the rear sprocket of the present disclosure, it is possible to provide a rear sprocket with high strength and rigidity.

1 is a schematic diagram of a human-powered vehicle including a rear sprocket according to an embodiment; FIG. 2 is an exploded perspective view of a rear hub assembly and a rear sprocket assembly included in the manpowered vehicle of FIG. 1; FIG. 3 is an exploded perspective view of the rear sprocket assembly of FIG. 2; FIG. 3 is a partial cross-sectional view of the rear sprocket assembly of FIG. 2; FIG. FIG. 3 is a perspective view of a rear sprocket included in the rear sprocket assembly of FIG. 2; FIG. 6 is a cross-sectional perspective view of the rear sprocket of FIG. 5; FIG. 6 is a partial side view of the rear sprocket of FIG. 5; The perspective view which looked at the rear sprocket of FIG. 5 from the other side. The perspective view of the rear sprocket which concerns on the example of a change. The perspective view of the rear sprocket which concerns on another example of a change.

<First embodiment>
A rear sprocket according to an embodiment will be described with reference to FIGS. 1 to 8. FIG. The manpowered vehicle 10 shown in FIG. 1 is a vehicle that has at least one wheel and can be driven by at least manpower. The human powered vehicle 10 includes various types of bicycles, such as mountain bikes, road bikes, city bikes, cargo bikes, hand bikes, and recumbent bikes. The number of wheels that the manpowered vehicle 10 has is not limited. Manpowered vehicles 10 also include, for example, unicycles and vehicles having two or more wheels. The manpowered vehicle 10 is not limited to vehicles that can be driven solely by manpower. The human-powered vehicle 10 includes an E-bike that uses not only the human-powered driving force but also the driving force of an electric motor for propulsion. E-bikes include electrically assisted bicycles whose propulsion is assisted by an electric motor. Hereinafter, in the embodiments, the manpowered vehicle 10 will be described as a bicycle.

As used herein, the following directional terms "front", "rear", "forward", "backward", "left", "right", "lateral", "upward", and , “downward”, and any other similar directional terms are defined with respect to the rider in a reference position (e.g., on the saddle or seat) of the manpowered vehicle 10 and facing the handlebars. pointing in the direction.

As shown in FIG. 1 , manpowered vehicle 10 includes frame 12 , crank 14 , front sprocket 16 , chain 18 , rear hub assembly 30 and rear sprocket assembly 40 . Crank 14 and rear hub assembly 30 are attached to frame 12 . A front sprocket 16 is attached to the crank 14 .

Crank 14 includes a crankshaft 20 and a pair of crank arms 22 . A pair of crank arms 22 are attached to the crankshaft 20 . A pedal 24 is rotatably connected to each of the pair of crank arms 22 .

Chain 18 is wound around front sprocket 16 and rear sprocket 42 included in rear sprocket assembly 40 . Chain 18 transmits the human drive force applied to pedals 24 from front sprocket 16 to rear sprocket assembly 40 . For example, chain 18 includes inner links, outer links, and rollers.

As shown in FIG. 2, the rear hub assembly 30 includes a hub axle, a hub body 32 rotatably mounted on the hub axle, and a sprocket support 34 rotatably mounted on the hub axle. Hub body 32 includes a pair of spoke attachment portions 36 . Each of the pair of spoke attachment portions 36 has at least one spoke attachment hole 36A. Spokes are attached to the spoke attachment holes 36A. Sprocket support 34 has external spline teeth 38 on its outer circumference.

As shown in FIGS. 2-4, rear sprocket assembly 40 includes rear sprocket 42 attachable to rear hub assembly 30 . Rear sprocket assembly 40 may include a plurality of rear sprockets 42 . For example, the plurality of rear sprockets 42 includes eight rear sprockets 42A, 42B, 42C, 42D, 42E, 42F, 42G, 42H. A rear transmission system including a rear sprocket assembly 40 changes the chain 18 from one rear sprocket 42 to another of a plurality of rear sprockets 42 in response to operation of a shift operating device.

Rear sprocket assembly 40 further includes a sprocket carrier 44 that holds rear sprocket 42 . In FIG. 3, illustration of the sprocket carrier 44 and the largest sprocket 42A of the plurality of rear sprockets 42 is omitted. In this embodiment, sprocket carrier 44 includes six extensions 46 . Each extension 46 has a retainer that retains the rear sprocket 42 . Sprocket carrier 44 has internal spline teeth 44A configured to engage external spline teeth 38 carried by sprocket support 34 . The rear sprocket assembly 40 is rotatably attached to the sprocket support 34 by engaging the rear sprocket assembly 40 with the sprocket support 34 via the inner spline teeth 44A.

The rear sprocket 42 has a sprocket body 50 . The sprocket body 50 includes an axially outward surface 52 and an axially inward surface 54 provided on the opposite side of the axially outward surface 52 in the axial direction AD about the rotation center axis CA of the rear sprocket 42 . . The axially inward surface 54 is configured to face the axial center plane CS of the manpowered vehicle 10 in the axial direction AD in the mounted state in which the rear sprocket assembly 40 including the rear sprocket 42 is mounted to the rear hub assembly 30 . An axial center plane CS of the manpowered vehicle 10 is shown in FIGS. 1 and 4 . For example, the axial centerplane CS of the manpowered vehicle 10 is substantially coincident with the lateral center of the manpowered vehicle 10 .

As shown in FIGS. 2-8, sprocket body 50 is configured to be spaced apart from sprocket support 34 of rear hub assembly 30 in an installed condition in which rear sprocket assembly 40 including rear sprocket 42 is installed on rear hub assembly 30 . and at least one attachment portion 58 configured to attach to one of the sprocket carrier 44 of the rear sprocket assembly 40 and another rear sprocket of the rear sprocket assembly 40 .

All of the multiple rear sprockets 42 may be directly attached to the sprocket carrier 44 . Some of the plurality of rear sprockets 42 may be directly attached to the sprocket carrier 44 and the remaining rear sprockets 42 may be attached to the sprocket carrier 44 via another rear sprocket 42 of the rear sprocket assembly 40 .

In the example shown in FIGS. 2-4, the third through eighth rear sprockets 42C through 42H, counting from the largest sprocket 42A, are mounted directly to the sprocket carrier 44. In the example shown in FIGS. For each of the third through eighth rear sprockets 42C through 42H, the sprocket body 50 may have six mounting portions 58 corresponding to the retaining portions provided by the six extensions 46 of the sprocket carrier 44, respectively. . The mounting portion 58 may include, for example, a mounting hole provided near the radially inner circumferential portion 56 . The sprocket body 50 may be attached to the sprocket carrier 44 by rivets inserted into the mounting holes and holes formed in the retainer. The sprocket body 50 is mounted such that the axially inward facing surface 54 contacts the retainer. Rear sprocket assembly 40 is attached to rear hub assembly 30 by attaching sprocket carrier 44 to sprocket support 34 . This allows the radially inner circumference 56 to move away from the sprocket support 34 .

For example, in the example shown in FIGS. 2-4 , the largest sprocket 42 A and the second rear sprocket 42 B counting from the largest sprocket 42 A are attached to another rear sprocket 42 of the rear sprocket assembly 40 . The largest sprocket 42A is attached to the second rear sprocket 42B. The second rear sprocket 42B is attached to the third rear sprocket 42C counting from the largest sprocket 42A. For example, the largest sprocket 42A and the second rear sprocket 42B may have mounting portions 58 that include mounting holes. The second rear sprocket 42B may be attached to the third rear sprocket 42C by rivets inserted into the attachment holes. The largest sprocket 42A may be attached to the second rear sprocket 42B by rivets inserted through the attachment holes.

As shown in FIGS. 3-7, the rear sprocket 42 has at least one first axial projection formed on the radially inner periphery 56 so as to be an integral unitary member with the sprocket body 50. A unit 60 is provided. That is, the first axial protrusion 60 is formed integrally with the sprocket body 50 from the same material as the sprocket body 50 .

For example, the at least one first axial protrusion 60 extends continuously over at least one-sixth of the entire circumference of the radially inner peripheral portion 56 in the circumferential direction about the rotation center axis CA. For example, the at least one first axial projection 60 extends circumferentially continuously over at least one quarter of the total circumference of the radially inner circumference 56 . For example, the at least one first axial projection 60 extends circumferentially continuously over at least half the circumference of the radially inner circumference 56 . In this embodiment, the at least one first axial projection 60 extends continuously around the entire circumference of the radially inner circumference 56 in the circumferential direction.

At least one first axial projection 60 is non-circular. In this embodiment, the radially inner peripheral portion 56 of the rear sprocket 42 is non-circular and protrudes radially inward at six portions corresponding to the mounting portions 58 . A first axial protrusion 60 extending along the radially inner peripheral portion 56 has the same shape as the radially inner peripheral portion 56 and protrudes radially inward at six portions corresponding to the mounting portions 58 .

As shown in FIGS. 3-8, rear sprocket 42 has at least one lightening hole 62 . Rear sprocket 42 includes at least one second axial projection 64 formed around at least one lightening hole 62 so as to be a unitary member integral with sprocket body 50 . That is, the second axial protrusion 64 is formed integrally with the sprocket body 50 from the same material as the sprocket body 50 . As shown in FIG. 6, the sprocket body 50, first axial protrusion 60, and second axial protrusion 64 are constructed as a single piece with no joints or interfaces between them. be done. The rear sprocket 42 is made of metal, for example. The rear sprocket 42 is formed, for example, by punching sheet metal.

At least one second axial projection 64 completely surrounds at least one lightening hole 62 . For example, the rear sprocket 42 shown in FIGS. 5-8 is the fifth rear sprocket 42E counted from the largest sprocket 42A and has six lightening holes 62. As shown in FIG. A second axial protrusion 64 is formed around each lightening hole 62 to surround the entire circumference of the lightening hole 62 .

At least one first axial projection 60 has a proximal end 60A integrally connected to the sprocket body 50, as shown in FIGS. The at least one first axial protrusion 60 also has a free distal end 60B configured not to contact another rear sprocket 42 of the rear sprocket assembly 40 in the assembled condition of the rear sprocket assembly 40 . At least one second axial projection 64 has a proximal end 64A integrally connected to sprocket body 50 . The at least one second axial protrusion 64 also has a free distal end 64B configured not to contact another rear sprocket 42 of the rear sprocket assembly 40 in the assembled condition of the rear sprocket assembly 40 . That is, the amount of protrusion of the first axial protrusion 60 and the second axial protrusion 64 is smaller than the distance between the adjacent rear sprockets 42 in the rear sprocket assembly 40 . If the first axial protrusion 60 and the second axial protrusion 64 do not overlap the adjacent rear sprockets 42 in the radial direction about the rotation center axis CA, the first axial protrusion 60 and the second axial protrusion 64 The amount of protrusion of the second axial protrusion 64 may be equal to the distance between adjacent rear sprockets 42 in the rear sprocket assembly 40 .

At least one first axial projection 60 extends axially AD from the axially inwardly facing surface 54 at the radially inner periphery 56 away from the axially outwardly facing surface 52 . At least one second axial projection 64 extends axially AD from the axially inwardly facing surface 54 at the radially inner periphery 56 away from the axially outwardly facing surface 52 . That is, the first axial protrusion 60 and the second axial protrusion 64 extend from the axially inward surface 54 toward the axial center plane CS.

As shown in FIGS. 2-4, the rear sprocket 42 having the first axial protrusion 60 and the second axial protrusion 64 is axially axial AD when the rear sprocket assembly 40 is assembled. It is configured to be positioned axially outward from the largest sprocket 42A of the assembly 40 . The rear sprocket closest to the axial center plane CS of the manpowered vehicle 10 in the axial direction AD is the largest sprocket 42A. In this embodiment, all rear sprockets 42 other than the largest sprocket 42A have a first axial protrusion 60 and a second axial protrusion 64. As shown in FIG. At least one of the rear sprockets 42 other than the largest sprocket 42A may have the first axial protrusion 60 and the second axial protrusion 64. As shown in FIG.

The shape of the radially inner circumferential portion 56 and the first axial protrusion 60 may be the same for all the rear sprockets 42 or may be different for each rear sprocket 42 . The shape, number, and arrangement of the lightening holes 62 and the second axial projections 64 may be the same for all the rear sprockets 42 or may be different for each rear sprocket 42 .

As shown in FIGS. 2 to 10, the rear sprocket 42 has a plurality of sprocket teeth 70 extending radially outward from the outer peripheral portion of the sprocket body 50 in the radial direction about the rotation center axis CA. Each sprocket tooth 70 has a drive surface facing away from the drive rotational direction RD and a non-drive surface facing the drive rotational direction RD. The rollers of chain 18 engage the drive surface. The engagement of the chain 18 with the sprocket teeth 70 transfers the human drive force through the chain 18 to the rear sprocket assembly 40 .

5-10, on each rear sprocket 42, the plurality of sprocket teeth 70 comprise at least one downshift-facilitating tooth 72 and at least one upshift-facilitating tooth 74. include. In this embodiment, as shown in FIG. 8, the downshift facilitating teeth 72 include a first downshift facilitating tooth 72A, a second downshift facilitating tooth 72B, and a third downshift facilitating tooth 72C. The first downshift-promoting tooth 72A and the second downshift-promoting tooth 72B are teeth that are stepped so as to be recessed from the axially outward surface 52 toward the axially inward surface 54 in the axial direction AD. be. The tip of the third downshift facilitating tooth 72C is inclined in the axial direction AD from the driving surface toward the non-driving surface so as to approach the axially outward surface 52 .

The first downshift facilitating tooth 72A and the second downshift facilitating tooth 72B are recessed toward the axially inward facing surface 54 relative to the third downshift facilitating tooth 72C. Therefore, when the chain 18 engaged with the adjacent small sprocket is moved toward the rear sprocket 42 by the rear derailleur during a downshift operation, the outer link and the inner link of the chain 18 move to the first downshift. It leans toward the axially inward surface 54 at locations corresponding to the shift-promoting tooth 72A and the second downshift-promoting tooth 72B. Further, the tip of the third downshift promoting tooth 72C is inclined from the driving surface toward the non-driving surface so as to approach the axially outward surface 52 . Therefore, during a downshift operation, the outer links of the chain 18 engaging the adjacent small sprockets tend to engage the third downshift facilitating teeth 72C at locations corresponding to the third downshift facilitating teeth 72C. . After the outer link engages with the third downshift promoting tooth 72C, as the rear sprocket 42 rotates in the drive rotation direction RD, the chain 18 sequentially shifts from the adjacent small sprocket to the rear sprocket 42, and down. Shift operation is completed.

The upshift facilitating teeth 74 include a first upshift facilitating tooth 74A, a second upshift facilitating tooth 74B, and a third upshift facilitating tooth 74C. The second upshift-promoting tooth 74B and the third upshift-promoting tooth 74C are teeth that are stepped so as to be recessed from the axially outward surface 52 toward the axially inward surface 54 in the axial direction AD. be. The tip of the first upshift promoting tooth 74A is inclined in the axial direction AD from the non-driving surface toward the driving surface so as to approach the axially outward surface 52 . That is, the tip of the first upshift promoting tooth 74A inclines in the opposite direction to the tip of the third downshift promoting tooth 72C.

During an upshift operation, when the outer link of the chain 18 is positioned on the first upshift facilitating tooth 74A and the inner link of the chain 18 is positioned on the second upshift facilitating tooth 74B, it is positioned on the second upshift facilitating tooth 74B. The inner link disengages from the second upshift facilitating tooth 74B. Since the tip of the first upshift promoting tooth 74A is inclined from the non-driving surface toward the driving surface so as to approach the axially outward surface 52, the chain 18 is pulled toward the adjacent small sprocket. Further, the second upshift promoting tooth 74B is recessed toward the axially inward facing surface 54. As shown in FIG. Therefore, the chain 18 pulled by the rear derailleur toward the adjacent small sprocket is likely to come off the second upshift promoting tooth 74B. Even if the inner link of the chain 18 disengages from the second upshift facilitating tooth 74B, the outer link may still engage the sprocket tooth 70 following the second upshift facilitating tooth 74B. Therefore, the sprocket tooth 70 succeeding the second upshift promoting tooth 74B is also formed as a third upshift promoting tooth 74C recessed toward the axially inward surface 54 . When the inner link located on the second upshift facilitating tooth 74B disengages from the second upshift facilitating tooth 74B, the outer link located on the third upshift facilitating tooth 74C disengages from the third upshift facilitating tooth 74C. After that, as the rear sprocket 42 rotates in the drive rotation direction RD, the chain 18 sequentially shifts from the rear sprocket 42 to the adjacent small sprocket, completing the upshift operation.

As shown in FIG. 7, the at least one first axial protrusion 60 has at least one downshift-enhancing tooth 72 and at least one upshift-enhancing tooth 74 in the circumferential direction when viewed in the axial direction AD. overlaps with at least one of In this embodiment, the first axial protrusion 60 extending continuously around the entire circumference of the radially inner circumference 56 is circumferentially aligned with all downshift-enhancing teeth 72 and all upshift-enhancing teeth 74. overlaps with

<Change example>
The descriptions of the embodiments are illustrative of possible forms of rear sprockets according to the present disclosure and are not intended to limit the forms. A rear sprocket according to the present disclosure may take a form in which, for example, modifications of the embodiments shown below and at least two modifications that are not mutually contradictory are combined. In the following modified examples, the same reference numerals as in the embodiment are given to the parts that are common to the embodiment, and the description thereof is omitted.

- As shown in FIG. 9, the first axial projection 60 may be divided into a plurality of parts instead of one continuous projection. In the example shown in FIG. 9 , the first axial protrusion 60 is split at a location corresponding to the mounting portion 58 . All the downshift facilitating teeth 72 and all the upshift facilitating teeth 74 may overlap any first axial protrusion 60 in the circumferential direction when viewed in the axial direction AD. At least some of the downshift-promoting tooth 72 and the upshift-promoting tooth 74 may not overlap the first axial projection 60 in the circumferential direction when viewed in the axial direction AD. When viewed from the axial direction AD, all of the first downshift-promoting tooth 72A, the second downshift-promoting tooth 72B, and the third downshift-promoting tooth 72C are circumferentially aligned with any of the first axial projections 60. May overlap. When viewed from the axial direction AD, only some of the first downshift-promoting teeth 72A, the second downshift-promoting teeth 72B, and the third downshift-promoting teeth 72C are arranged in any first axial direction in the circumferential direction. It may overlap with the protrusion 60 . When viewed from the axial direction AD, all of the first upshift-promoting tooth 74A, the second upshift-promoting tooth 74B, and the third upshift-promoting tooth 74C are circumferentially aligned with any of the first axial protrusions 60. May overlap. When viewed from the axial direction AD, only some of the first upshift-promoting tooth 74A, the second upshift-promoting tooth 74B, and the third upshift-promoting tooth 74C are arranged in any first axial direction in the circumferential direction. It may overlap with the protrusion 60 .

- As shown in Figure 10, the second axial projection 64 does not have to completely surround the lightening hole 62; The second axial protrusion 64 may surround at least a portion of the perimeter of the lightening hole 62 . The second axial protrusion 64 may be divided into a plurality of protrusions instead of one protrusion extending continuously.

- As shown in FIG. 9, the rear sprocket 42 does not have to have the second axial protrusion 64 as long as it has the first axial protrusion 60 . For example, in the example shown in FIG. 9, the rear sprocket 42 does not have the lightening holes 62 and the second axial protrusions 64 .

- As shown in FIG. 10, the rear sprocket 42 has at least one axial projection formed around at least one lightening hole 62 so as to be an integral unitary member with the sprocket body 50; The first axial protrusion 60 may not be provided as long as the first axial protrusion 60 is provided. The at least one axial protrusion in this modification is a second axial protrusion 64 . For example, in the example shown in FIG. 10 , the rear sprocket 42 does not have the first axial protrusion 60 .

- At least one of the rear sprockets 42 other than the largest sprocket 42A may have at least one of the first axial protrusion 60 and the second axial protrusion 64 .

- The second axial projections 64 may not be formed around some of the lightening holes 62 . That is, the second axial protrusion 64 may be formed around at least some of the lightening holes 62 of the rear sprocket 42 .

As used herein, the phrase "at least one" means "one or more" of the desired option. As an example, the expression "at least one" as used herein means "only one option" if the number of options is two, or "both of the two options". As another example, the expression "at least one" used in this specification means "only one option" if the number of options is three or more, or "any combination of two or more options ” means.

DESCRIPTION OF SYMBOLS 10... Manpowered vehicle, 30... Rear hub assembly, 34... Sprocket support, 40... Rear sprocket assembly, 42... Rear sprocket, 42A... Largest sprocket, 44... Sprocket carrier, 50... Sprocket body, 52... Axial outward surface , 54... Axial inner surface, 56... Radial inner circumference, 58... Mounting part, 60... First axial projection, 60A... Proximal end, 60B... Free distal end, 62... Lightening hole, 64 Second axial protrusion 64A Proximal end 64B Free distal end 70 Sprocket tooth 72 Downshift promoting tooth 74 Upshift promoting tooth AD Axial direction CA Rotation center Axial center, CS... Axial center plane.

Claims (13)

A rear sprocket attachable to a rear hub assembly for a human powered vehicle, comprising:
A rear sprocket assembly including an axially outward surface, an axially inwardly facing surface provided on the opposite side of the axially outward surface in the axial direction about the rotation center axis of the rear sprocket, and the rear sprocket is attached to the rear hub. a radially inner periphery configured to move away from a sprocket support of the rear hub assembly, a sprocket carrier of the rear sprocket assembly, and one of another rear sprocket of the rear sprocket assembly in an installed condition attached to the assembly; and at least one attachment portion configured to be attached to a vehicle, wherein the axially inward facing surface is configured to face axially the axial center plane of the manpowered vehicle in the attached state. a sprocket body and
a plurality of sprocket teeth extending radially outward from an outer peripheral portion of the sprocket body in a radial direction about the rotation center axis;
at least one first axial projection formed on said radially inner periphery so as to be an integral unitary member with said sprocket body;
The at least one first axial protrusion is configured such that a proximal end integrally connected to the sprocket body and another rear sprocket of the rear sprocket assembly in an assembled state of the rear sprocket assembly do not contact each other. a free distal end formed by
said at least one first axial projection extends axially from said axially inwardly facing surface at said radially inner periphery away from said axially outwardly facing surface;
The at least one first axial projection extends continuously over at least one-sixth of the entire circumference of the radially inner circumference in a circumferential direction about the rotation center axis. 2. The rear sprocket according to claim 1, wherein the rear sprocket is arranged axially outward from a largest sprocket of the rear sprocket assembly in the axial direction in the assembled state of the rear sprocket assembly. 3. A rear sprocket according to claim 1 or 2, wherein said at least one first axial projection extends continuously in said circumferential direction over at least a quarter of the total circumference of said radially inner circumference. 4. A rear sprocket according to claim 3, wherein said at least one first axial projection extends continuously in said circumferential direction over at least half of the circumference of said radially inner circumference. 5. The rear sprocket according to claim 4, wherein said at least one first axial projection extends continuously around said radially inner circumference in said circumferential direction. 6. The rear sprocket of claim 5, wherein said at least one first axial projection is non-circular. 7. A rear sprocket according to any preceding claim, further comprising at least one second axial projection extending around at least one lightening hole formed in the sprocket body. 8. The rear sprocket of any preceding claim, wherein the plurality of sprocket teeth includes at least one of at least one downshift facilitating tooth and at least one upshift facilitating tooth. When viewed in the axial direction, the at least one first axial protrusion is, in the circumferential direction, the at least one of the at least one downshift-facilitating tooth and the at least one upshift-facilitating tooth. 9. The rear sprocket of claim 8, which overlaps. A rear sprocket attachable to a rear hub assembly for a human powered vehicle, comprising:
It has an axially outward surface, an axially inward surface provided on the opposite side of the axially outward surface in the axial direction about the rotation center axis of the rear sprocket, and at least one lightening hole. , the axially inwardly facing surface is configured to axially face the axial center surface of the manpowered vehicle in an attached state in which a rear sprocket assembly including the rear sprocket is attached to the rear hub assembly; body and
a plurality of sprocket teeth extending radially outward from an outer peripheral portion of the sprocket body in a radial direction about the rotation center axis;
at least one axial projection formed around said at least one lightening hole so as to be a unitary member integral with said sprocket body. 11. The rear sprocket of claim 10, wherein said at least one axial protrusion extends axially from said axially inwardly facing surface away from said axially outwardly facing surface. The at least one axial protrusion is configured to have a proximal end integrally connected to the sprocket body and not to contact another rear sprocket of the rear sprocket assembly in an assembled state of the rear sprocket assembly. 12. A rear sprocket according to claim 10 or 11, having a free distal end. 13. A rear sprocket according to any one of claims 10 to 12, wherein said at least one axial projection completely surrounds said at least one lightening hole.

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