Rear chainring

Abstract

[The technical problem to be solved] We need to provide a rear sprocket that is both high-strength and highly rigid. Technical means to solve the problem The rear sprocket includes: a sprocket body, a plurality of sprocket teeth extending radially outward from the outer periphery of the sprocket body, and at least one first axial protrusion formed as a single component integral with the sprocket body in the radially inner periphery. The at least one first axial protrusion has: a proximal end and a free distal end; the proximal end is integrally connected to the sprocket body; the free distal end, in the assembled state of the rear sprocket assembly, does not contact other rear sprockets in the rear sprocket assembly. The at least one first axial protrusion extends radially inward from the inner axial side away from the outer axial side in the radially inner periphery. The at least one first axial protrusion extends continuously in the circumferential direction relative to the rotation center axis, covering at least one-sixth of the entire circumference of the radially inner periphery.

Description

Technical Field

[0001] This invention relates to the rear sprocket. Prior Technology

[0002] For example, Figure 20 of Patent Document 1 discloses: rear sprockets 334, 336, 338, and 340 mounted on sprocket carriers 339 and 341, rear sprocket 32 ​​mounted on rear sprocket 334, and rear sprocket 30 mounted on rear sprocket 32. [Previous Technical Documents] [Patent Literature]

[0003] [Patent Document 1] U.S. Patent Application Publication No. 2008 / 0004143 Summary of the Invention

[0004] [The problem the invention aims to solve]

[0005] The rear sprockets 30, 32, 334, 336, 338, and 340 disclosed in Patent Document 1 are mounted on a sprocket carrier or other sprockets in the assembled state of the rear sprocket assembly, such that the inner periphery of the rear sprocket is radially away from the sprocket support of the rear hub assembly.

[0006] The rear sprockets 30, 32, 334, 336, 338, and 340 in Patent Document 1, if made thinner for the purpose of weight reduction, tend to have lower strength and rigidity.

[0007] One object of the present invention is to provide a rear sprocket with high strength and high rigidity. [Methods used to solve problems]

[0008] The first embodiment of the present invention provides a rear sprocket that can be mounted on a rear wheel hub assembly of a manually driven vehicle. It comprises: a sprocket body, a plurality of sprocket teeth, and at least one first axially oriented protrusion. The sprocket body has: an axially oriented outer surface, an axially oriented inner surface, a radially inner peripheral portion, and at least one mounting portion. The axially oriented inner surface is located opposite to the axially oriented outer surface in the axial direction relative to the rotation center axis of the rear sprocket. The radially inner peripheral portion, in the mounting state where the rear sprocket assembly including the rear sprocket is mounted on the rear wheel hub assembly, is located away from the sprocket support of the rear wheel hub assembly. The at least one mounting portion is mounted on the sprocket carrier of the rear sprocket assembly and one of the other rear sprockets in the rear sprocket assembly. The axially oriented inner surface, in the mounting state, faces the axially oriented center surface of the manually driven vehicle in the axial direction. The aforementioned plurality of sprocket teeth extend radially outward from the outer periphery of the sprocket body relative to the aforementioned rotation center axis; the aforementioned at least one first axial direction protrusion is formed as a single component integrated with the aforementioned sprocket body in the aforementioned radial inner periphery; the aforementioned at least one first axial direction protrusion has: a proximal end and a free distal end; the aforementioned proximal end is integrally connected to the aforementioned sprocket body; the aforementioned free distal end, in the assembled state of the aforementioned rear sprocket assembly, does not contact other rear sprockets of the aforementioned rear sprocket assembly; the aforementioned at least one first axial direction protrusion extends radially outward from the aforementioned axial direction inner surface in the aforementioned radial inner periphery away from the aforementioned axial direction outer surface; the aforementioned at least one first axial direction protrusion extends continuously in the circumferential direction relative to the aforementioned rotation center axis, covering at least one-sixth of the entire circumference of the aforementioned radial inner periphery. The first type of rear sprocket features a first axial protrusion, an integral component formed on the radial inner circumference of the sprocket body, which functions as a reinforcing rib. Furthermore, this first axial protrusion extends from the inner axial side away from the outer axial side, preventing it from colliding with the chain, which engages with the adjacent small sprocket. By preventing collisions with the chain engaging with the adjacent small sprocket, the strength and rigidity of the rear sprocket are effectively improved.

[0009] According to the second embodiment of the first embodiment of the present invention, in the above-described assembly state of the rear sprocket assembly, the rear sprocket is arranged outward in the axial direction from the largest sprocket of the rear sprocket assembly. With the second type of rear sprocket, the chain that is engaged with the adjacent small sprocket will not collide, thus effectively improving the strength and rigidity of the rear sprocket.

[0010] According to the first or second type of the present invention, the rear sprocket of the third type has at least one first axial direction protrusion that extends continuously in the circumferential direction and covers at least one-quarter of the entire circumference of the radial inner circumference. With the third type of rear sprocket, the strength and rigidity of the rear sprocket can be further improved because the protrusion in the first axis direction is extended longer.

[0011] According to the third and fourth embodiments of the present invention, the rear sprocket has at least one first axial direction protrusion that extends continuously in the circumferential direction and covers at least half of the entire circumference of the radial inner circumference. With the fourth type of rear sprocket, the strength and rigidity of the rear sprocket can be further improved because the protrusion in the first axis direction is extended longer.

[0012] According to the fourth and fifth embodiments of the present invention, the rear sprocket has at least one first axial direction protrusion that extends continuously in the circumferential direction and covers the entire circumference of the radial inner circumference. With the fifth type of rear sprocket, the strength and rigidity of the rear sprocket can be further improved because the protrusion in the first axis direction is extended longer.

[0013] According to the fifth and sixth embodiments of the present invention, the rear sprocket has at least one non-circular protrusion in the first axial direction. The strength and rigidity of the rear sprocket can be further improved by using the sixth type of rear sprocket.

[0014] The rear sprocket of the seventh type according to any one of the first to sixth types of the present invention further includes at least one second axial direction protrusion, which extends around at least one lightweight hole formed in the sprocket body. With the seventh type of rear sprocket, the second axial protrusion extending around the lightweight hole also functions as a reinforcing rib. Thus, it is possible to simultaneously achieve: lightweighting of the rear sprocket and improvement of its strength and rigidity.

[0015] According to the eighth type of any of the first to seventh types of the present invention, the plurality of sprocket teeth include at least one of at least one downshifting promoting tooth and at least one upshifting promoting tooth. With the rear sprocket of the Type 8, due to the excellent strength and rigidity of the rear sprocket, a stable and smooth gear shifting action can be achieved.

[0016] According to the eighth and ninth embodiments of the present invention, the at least one first axial direction protrusion overlaps with at least one of the at least one downshifting promoting teeth and at least one upshifting promoting teeth in the circumferential direction when viewed from the axial direction. The rear sprocket of the ninth type has at least one downshifting actuating tooth and an upshifting actuating tooth to facilitate gear shifting, which enhances strength and rigidity through the protrusion in the first axial direction, thus achieving a more stable and smooth gear shifting action.

[0017] The tenth embodiment of the present invention is a rear sprocket that can be installed in a rear wheel hub assembly of a manually driven vehicle, and includes: a sprocket body, a plurality of sprocket teeth, and at least one axially oriented protrusion; the sprocket body has: an axially oriented outer surface, an axially oriented inner surface disposed on the opposite side of the axially oriented outer surface in the axial direction relative to the rotation center axis of the rear sprocket, and at least one lightweight hole; the axially oriented inner surface faces the axially oriented center surface of the manually driven vehicle in the axial direction when the rear sprocket assembly including the rear sprocket is installed in the rear wheel hub assembly; the plurality of sprocket teeth extend radially outward from the outer periphery of the sprocket body in the radial direction relative to the rotation center axis; the at least one axially oriented protrusion is formed as a single component integrated with the sprocket body and is formed around the at least one lightweight hole. The rear sprocket of the 10th type is lightweight by means of a lightweight bore, and the axial protrusion functions as a reinforcing rib. Thus, it is possible to achieve lightweighting while effectively improving the strength and rigidity of the rear sprocket.

[0018] According to the 10th and 11th embodiments of the present invention, the rear sprocket has at least one axial protrusion extending from the inner axial side toward the axial direction and away from the outer axial side. With the rear sprocket of type 11, the chain that is engaged with the small sprocket of the adjacent rear sprocket will not collide, thus effectively improving the strength and rigidity of the rear sprocket.

[0019] According to the 10th or 11th type of the present invention, the rear sprocket of the 12th type has at least one axial protrusion having a proximal end and a free distal end; the proximal end is integrally connected to the sprocket body; and the free distal end does not contact other rear sprockets of the rear sprocket assembly in the assembled state of the rear sprocket assembly. The rear sprocket of type 12 can achieve lightweighting and effectively improve the strength and rigidity of the rear sprocket.

[0020] According to the 13th type of at least one type of the 10th to 12th types of the present invention, the at least one axial protrusion completely surrounds the at least one lightweight hole. By using the rear sprocket of the 13th type, the entire area around the lightweight hole is reinforced by the axial protrusion, thus achieving lightweighting and effectively improving the strength and rigidity of the rear sprocket. [Invention Effects]

[0021] The rear sprocket of the present invention provides a rear sprocket with high strength and high rigidity. Simple Explanation of the Diagram

[0022] [Figure 1] is a schematic diagram of a human-powered vehicle including the rear sprocket of the embodiment. [Figure 2] is an exploded perspective view of the rear wheel hub assembly and rear sprocket assembly of the human-powered vehicle shown in Figure 1. [Figure 3] is an exploded perspective view of the rear sprocket assembly in Figure 2. [Figure 4] is a partial cross-sectional view of the rear sprocket assembly in Figure 2. [Figure 5] is a perspective view of the rear sprocket of the rear sprocket assembly in Figure 2. [Figure 6] is a cross-sectional perspective view of the rear sprocket in Figure 5. [Figure 7] is a partial side view of the rear sprocket in Figure 5. [Figure 8] is a perspective view of the rear sprocket in Figure 5 viewed from the opposite side. [Figure 9] is a perspective view of the rear sprocket of the modified example. [Figure 10] is a perspective view of the rear sprocket in other modified examples. Implementation

[0023] <First Implementation>

[0024] Referring to Figures 1 to 8, the rear sprocket of this embodiment will be described. As shown in Figure 1, the human-powered vehicle 10 has at least one wheel and is a vehicle that can be driven by at least human power. The human-powered vehicle 10 includes, for example, various types of bicycles such as mountain bikes, road bikes, city bikes, cargo bikes, hand-cranked bicycles, and recumbent bicycles. The number of wheels in the human-powered vehicle 10 is not limited. The human-powered vehicle 10 also includes, for example, unicycles and vehicles with two or more wheels. The human-powered vehicle 10 is not limited to vehicles driven solely by human power. The human-powered vehicle 10 includes electric bicycles (E-bikes) that are propelled not only by human power but also by the driving force of an electric motor. Electric bicycles include electric-assisted bicycles that are propelled with the assistance of an electric motor. Hereinafter, the human-powered vehicle 10 will be described as a bicycle.

[0025] In this instruction manual, the terms “front,” “back,” “forward,” “rear,” “left,” “right,” “horizontal,” “above,” and “below,” as well as any other similar directional terms, represent directions determined relative to the rider facing the handlebars in the reference direction of the human-powered vehicle 10 (e.g., on the saddle or seat).

[0026] As shown in Figure 1, the human-powered vehicle 10 includes: a frame 12, a crank 14, a front sprocket 16, a chain 18, a rear wheel hub assembly 30, and a rear sprocket assembly 40. The crank 14 and the rear wheel hub assembly 30 are mounted on the frame 12. The front sprocket 16 is mounted on the crank 14.

[0027] The crank 14 includes a crankshaft 20 and a pair of crank arms 22. The pair of crank arms 22 are mounted on the crankshaft 20. The pedals 24 are rotatably connected to each of the pair of crank arms 22.

[0028] Chain 18 is wound around: front sprocket 16 and rear sprocket 42 included in rear sprocket assembly 40. Chain 18 transmits the human driving force applied to pedal 24 from front sprocket 16 to rear sprocket assembly 40. For example, chain 18 has inner chain links, outer chain links, and rollers.

[0029] As shown in Figure 2, the rear wheel hub assembly 30 includes: a hub axle, a hub body 32 rotatably mounted to the hub axle, and a sprocket support 34 rotatably mounted to the hub axle. The hub body 32 has a pair of spoke mounting portions 36. Each of the pair of spoke mounting portions 36 has at least one spoke mounting hole 36A. Spokes are mounted in the spoke mounting holes 36A. The sprocket support 34 has outer spline teeth 38 on its outer periphery.

[0030] As shown in Figures 2 to 4, the rear sprocket assembly 40 includes a rear sprocket 42, which can be mounted on the rear hub assembly 30. The rear sprocket assembly 40 may also include a plurality of rear sprockets 42. For example, the plurality of rear sprockets 42 may include eight rear sprockets 42A, 42B, 42C, 42D, 42E, 42F, 42G, and 42H. The rear derailleur system including the rear sprocket assembly 40 switches the chain 18 from one of the rear sprockets 42 to another in response to the operation of the shifting device.

[0031] The rear sprocket assembly 40 further includes a sprocket carrier 44 for holding the rear sprocket 42. Figure 3 omits an illustration of the sprocket carrier 44 and the largest sprocket 42A among the plurality of rear sprockets 42. In this embodiment, the sprocket carrier 44 has six extensions 46. Each extension 46 has a holding portion for holding the rear sprocket 42. The sprocket carrier 44 has inner splines 44A that engage with outer splines 38 of the sprocket support 34. By engaging the rear sprocket assembly 40 with the sprocket support 34 via the inner splines 44A, the rear sprocket assembly 40 is integrally rotatably mounted on the sprocket support 34.

[0032] The rear sprocket 42 includes a sprocket body 50. The sprocket body 50 includes an outer surface 52 in the axial direction and an inner surface 54 in the axial direction, located in the axial direction AD relative to the rotation center axis CA of the rear sprocket 42, opposite to the outer surface 52. In the mounting state where the rear sprocket assembly 40, including the rear sprocket 42, is mounted on the rear wheel hub assembly 30, the inner surface 54 faces the axial direction center plane CS of the manually driven vehicle 10 in the axial direction AD. The axial direction center plane CS of the manually driven vehicle 10 is shown in Figures 1 and 4. For example, the axial direction center plane CS of the manually driven vehicle 10 substantially coincides with the center of the manually driven vehicle 10 in the lateral direction.

[0033] As shown in Figures 2 to 8, the sprocket body 50 has: a radially inner peripheral portion 56 that is separated from the sprocket support 34 of the rear wheel hub assembly 30 when the rear sprocket assembly 40, which includes the rear sprocket 42, is mounted on the rear wheel hub assembly 30; and at least one mounting portion 58 that is mounted on the sprocket carrier 44 of the rear sprocket assembly 40 and one of the other rear sprockets of the rear sprocket assembly 40.

[0034] Alternatively, all of the plurality of rear sprockets 42 may be directly mounted on the sprocket carrier 44. Alternatively, a portion of the plurality of rear sprockets 42 may be directly mounted on the sprocket carrier 44, while the remaining rear sprockets 42 may be mounted on the sprocket carrier 44 via the other rear sprockets 42 of the rear sprocket assembly 40.

[0035] In the examples shown in Figures 2 to 4, the third to eighth rear sprockets 42C to 42H, counting from the largest sprocket 42A, are directly mounted to the sprocket carrier 44. For each of the third to eighth rear sprockets 42C to 42H, the sprocket body 50 may also have six mounting portions 58, corresponding to the retaining portions of the six extensions 46 of the sprocket carrier 44. The mounting portions 58 may, for example, include mounting holes provided near the radially inner circumferential portion 56. The sprocket body 50 can also be mounted to the sprocket carrier 44 by rivets inserted into the mounting holes and the holes formed in the retaining portions. The sprocket body 50 is mounted such that its axially inner surface 54 contacts the retaining portion. The sprocket carrier 44 is mounted to the sprocket support 34, and the rear sprocket assembly 40 is mounted to the rear hub assembly 30. This allows the radially inner circumferential portion 56 to be separated from the sprocket support 34.

[0036] For example, in the examples shown in Figures 2 to 4, the largest sprocket 42A and the second rear sprocket 42B counting from the largest sprocket 42A are other rear sprockets 42 mounted on the rear sprocket assembly 40. The largest sprocket 42A is mounted on the second rear sprocket 42B. The second rear sprocket 42B is mounted on the third rear sprocket 42C counting from the largest sprocket 42A. For example, the largest sprocket 42A and the second rear sprocket 42B may also have a mounting portion 58 including a mounting hole. The second rear sprocket 42B may also be mounted on the third rear sprocket 42C by a rivet inserted into the mounting hole. The largest sprocket 42A may also be mounted on the second rear sprocket 42B by a rivet inserted into the mounting hole.

[0037] As shown in Figures 3 to 7, the rear sprocket 42 has at least one first axial protrusion 60, which is formed as a single component integrated with the sprocket body 50 in the radial inner circumference 56. That is, the first axial protrusion 60 is formed integrally with the sprocket body 50 using the same material.

[0038] For example, at least one first axial protrusion 60 extends continuously in the circumferential direction relative to the rotation center axis CA, covering at least one-sixth of the entire circumference of the radially inner circumference 56. For example, at least one first axial protrusion 60 extends continuously in the circumferential direction, covering at least one-quarter of the entire circumference of the radially inner circumference 56. For example, at least one first axial protrusion 60 extends continuously in the circumferential direction, covering at least one-half of the entire circumference of the radially inner circumference 56. In this embodiment, at least one first axial protrusion 60 extends continuously in the circumferential direction, covering the entire circumference of the radially inner circumference 56.

[0039] At least one first axial protrusion 60 is non-circular. In this embodiment, the radial inner circumference 56 of the rear sprocket 42 is non-circular and protrudes radially inward at six locations corresponding to the mounting portion 58. The first axial protrusion 60 extending along the radial inner circumference 56 has the same shape as the radial inner circumference 56 and protrudes radially inward at six locations corresponding to the mounting portion 58.

[0040] As shown in Figures 3 to 8, the rear sprocket 42 has at least one lightweight hole 62. The rear sprocket 42 also has at least one second-axis protrusion 64, which is formed as a single integral component with the sprocket body 50 around the lightweight hole 62. That is, the second-axis protrusion 64 is formed integrally with the sprocket body 50 using the same material. As shown in Figure 6, the sprocket body 50, the first-axis protrusion 60, and the second-axis protrusion 64 are a single part without any joints or interfaces between them. The rear sprocket 42 is, for example, made of metal. The rear sprocket 42 is formed, for example, by stamping sheet metal.

[0041] At least one second-axis protrusion 64 completely surrounds at least one lightweight hole 62. For example, in the rear sprocket 42 shown in Figures 5 to 8, the fifth rear sprocket 42E counting from the largest sprocket 42A has six lightweight holes 62. A second-axis protrusion 64 is formed around each lightweight hole 62, surrounding the entire circumference of the lightweight hole 62.

[0042] As shown in Figures 4 to 6, at least one first-axis protrusion 60 has a proximal end 60A integrally connected to the sprocket body 50. The at least one first-axis protrusion 60 also has a free distal end 60B; the free distal end 60B, in the assembled state of the rear sprocket assembly 40, does not contact the other rear sprockets 42 of the rear sprocket assembly 40. At least one second-axis protrusion 64 has a proximal end 64A integrally connected to the sprocket body 50. The at least one second-axis protrusion 64 also has a free distal end 64B; the free distal end 64B, in the assembled state of the rear sprocket assembly 40, does not contact the other rear sprockets 42 of the rear sprocket assembly 40. That is, the protrusion amount of the first-axis protrusion 60 and the second-axis protrusion 64 is less than the distance between 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 with the adjacent rear sprocket 42 in the radial direction relative to the rotation center axis CA, then the protrusion amount of the first axial protrusion 60 and the second axial protrusion 64 can also be equal to the distance between the adjacent rear sprockets 42 in the rear sprocket assembly 40.

[0043] At least one first axially oriented protrusion 60 extends radially from the inner axially oriented surface 54 toward the axially oriented AD and away from the outer axially oriented surface 52. At least one second axially oriented protrusion 64 extends radially from the inner axially oriented surface 54 toward the axially oriented AD and away from the outer axially oriented surface 52. That is, the first axially oriented protrusion 60 and the second axially oriented protrusion 64 extend from the inner axially oriented surface 54 toward the axially oriented center plane CS.

[0044] As shown in Figures 2 to 4, the rear sprocket 42, having a first axial direction protrusion 60 and a second axial direction protrusion 64, is arranged outward in the axial direction AD from the largest sprocket 42A of the rear sprocket assembly 40 in the assembled state of the rear sprocket assembly 40. In the axial direction AD, the rear sprocket closest to the axial direction center plane CS of the manually driven vehicle 10 is the largest sprocket 42A. In this embodiment, all rear sprockets 42 except the largest sprocket 42A have a first axial direction protrusion 60 and a second axial direction protrusion 64. Alternatively, at least one of the rear sprockets 42 other than the largest sprocket 42A may have a first axial direction protrusion 60 and a second axial direction protrusion 64.

[0045] The shapes of the radial inner circumference portion 56 and the first axial direction protrusion 60 may be the same on all rear sprockets 42 or different on each rear sprocket 42. The shape, number, and arrangement of the lightweight hole portion 62 and the second axial direction protrusion 64 may also be the same on all rear sprockets 42 or different on each rear sprocket 42.

[0046] As shown in Figures 2 to 10, the rear sprocket 42 has a plurality of sprocket teeth 70 extending radially outward from the outer periphery of the sprocket body 50 in a direction relative to the rotation center axis CA. Each sprocket tooth 70 has a driving surface facing the opposite direction to the driving rotation direction RD and a non-driving surface facing the driving rotation direction RD. The rollers of the chain 18 engage with the driving surface. By engaging the chain 18 with the sprocket teeth 70, the manual driving force is transmitted to the rear sprocket assembly 40 via the chain 18.

[0047] As shown in Figures 5 to 10, each rear sprocket 42 has a plurality of sprocket teeth 70, including at least one of at least one downshifting promoting tooth 72 and at least one upshifting promoting tooth 74. In various embodiments, as shown in Figure 8, the downshifting promoting tooth 72 includes a first downshifting promoting tooth 72A, a second downshifting promoting tooth 72B, and a third downshifting promoting tooth 72C. The first downshifting promoting tooth 72A and the second downshifting promoting tooth 72B are teeth that are machined in stages to be recessed from the outer surface 52 in the axial direction AD toward the inner surface 54 in the axial direction. The tip of the third downshifting promoting tooth 72C is inclined in the axial direction AD from the driving surface toward the non-driving surface to approach the outer surface 52 in the axial direction.

[0048] The first downshifting actuating teeth 72A and 72B are recessed further towards the inner side 54 in the axial direction than the third downshifting actuating tooth 72C. Therefore, during downshifting, when the chain 18, which engages with the adjacent pinion, moves towards the rear sprocket 42 via the rear derailleur, the portions of the outer and inner chain links of the chain 18 corresponding to the first downshifting actuating teeth 72A and 72B are closer to the inner side 54 in the axial direction. Furthermore, the tip of the third downshifting actuating tooth 72C is inclined from the driving surface towards the non-driving surface, approaching the outer side 52 in the axial direction. Therefore, during downshifting, the outer chain link of the chain 18, which engages with the adjacent pinion, easily engages with the third downshifting actuating tooth 72C at the portion corresponding to the third downshifting actuating tooth 72C. After the outer chain plate engages with the third downshifting accelerator tooth 72C, as the rear sprocket 42 rotates in the drive rotation direction RD, the chain 18 moves sequentially from the adjacent small sprocket to the rear sprocket 42, thus completing the downshifting action.

[0049] The upshift facilitator 74 includes: a first upshift facilitator 74A, a second upshift facilitator 74B, and a third upshift facilitator 74C. The second upshift facilitator 74B and the third upshift facilitator 74C are teeth that are machined in stages to be recessed from the outer axial side 52 towards the inner axial side 54 in the axial direction AD. The tip of the first upshift facilitator 74A is inclined in the axial direction AD from the non-driving surface towards the driving surface, approaching the outer axial side 52. That is, the tip of the first upshift facilitator 74A is inclined in the opposite direction to the tip of the third downshift facilitator 74C.

[0050] During upshifting, when the outer chain link of chain 18 is located at the first upshift actuating tooth 74A and the inner chain link of chain 18 is located at the second upshift actuating tooth 74B, the inner chain link located at the second upshift actuating tooth 74B disengages from the second upshift actuating tooth 74B. Since the tip of the first upshift actuating tooth 74A is inclined from the non-driving surface towards the driving surface to a near-axial outer surface 52, chain 18 is brought closer to the adjacent small sprocket. Furthermore, the second upshift actuating tooth 74B is recessed towards the axial inner surface 54. Therefore, chain 18, stretched towards the adjacent small sprocket by the rear derailleur, easily disengages from the second upshift actuating tooth 74B. Even if the inner chain link of chain 18 disengages from the second upshift actuating tooth 74B, the outer chain link may still engage with the subsequent sprocket tooth 70 of the second upshift actuating tooth 74B. Therefore, the subsequent sprocket tooth 70 of the second upshift promoting tooth 74B is also formed as a third upshift promoting tooth 74C recessed towards the inner side 54 in the axial direction. When the inner chain piece located at the second upshift promoting tooth 74B disengages from the second upshift promoting tooth 74B, the outer chain piece located at the third upshift promoting tooth 74C disengages from the third upshift promoting tooth 74C. Then, as the rear sprocket 42 rotates in the drive rotation direction RD, the chain 18 moves sequentially from the rear sprocket 42 to the adjacent small sprocket, thus completing the upshifting action.

[0051] As shown in FIG7, at least one first axial protrusion 60, viewed from the axial direction AD, overlaps with at least one of the aforementioned downshifting facilitator teeth 72 and at least one upshifting facilitator teeth 74 in the circumferential direction. In this embodiment, the first axial protrusion 60, which extends continuously throughout the entire circumference of the radially inner circumference portion 56, overlaps with all downshifting facilitator teeth 72 and all upshifting facilitator teeth 74 in the circumferential direction.

[0052] <Example of Change> The description of the embodiments is an example of the type of rear sprocket used in the present invention and is not intended to limit its type. The rear sprocket of the present invention may take the form of, for example, variations of the embodiments shown below and combinations of at least two variations that do not contradict each other. In the following variations, the parts common to the embodiments are marked with the same symbols as in the embodiments, and their descriptions are omitted.

[0053] As shown in Figure 9, the first axial direction protrusion 60 may not be a single, continuously extending protrusion, but may be divided into multiple parts. In the example shown in Figure 9, the first axial direction protrusions 60 are separated at the location corresponding to the mounting part 58. Viewed from the axial direction AD, all downshifting promoting teeth 72 and all upshifting promoting teeth 74 may overlap with any first axial direction protrusion 60 in the circumferential direction. Viewed from the axial direction AD, at least a portion of the downshifting promoting teeth 72 and upshifting promoting teeth 74 may not overlap with the first axial direction protrusion 60 in the circumferential direction. Viewed from the axial direction AD, all of the first downshifting promoting teeth 72A, the second downshifting promoting teeth 72B, and the third downshifting promoting teeth 72C may overlap with any first axial direction protrusion 60 in the circumferential direction. Viewed from the axial direction AD, only a portion of the first downshifting promoting teeth 72A, the second downshifting promoting teeth 72B, and the third downshifting promoting teeth 72C may overlap with any first axial direction protrusion 60 in the circumferential direction. Viewed from the axial direction AD, all of the first upshift promoting teeth 74A, the second upshift promoting teeth 74B, and the third upshift promoting teeth 74C may overlap with any of the first axial direction protrusions 60 in the circumferential direction. Alternatively, viewed from the axial direction AD, only a portion of the first upshift promoting teeth 74A, the second upshift promoting teeth 74B, and the third upshift promoting teeth 74C may overlap with any of the first axial direction protrusions 60 in the circumferential direction.

[0054] As shown in Figure 10, the second-axis protrusion 64 may completely surround the lightweight hole 62. Alternatively, the second-axis protrusion 64 may surround at least a portion of the lightweight hole 62. The second-axis protrusion 64 may not be a single, continuously extending protrusion, but may be divided into multiple parts.

[0055] As shown in Figure 9, the rear sprocket 42 may or may not have a second axial protrusion 64, provided it has a first axial protrusion 60. For example, in the example shown in Figure 9, the rear sprocket 42 does not have a lightweight hole 62 or a second axial protrusion 64.

[0056] As shown in Figure 10, the rear sprocket 42 may or may not have a first axial protrusion 60, provided that the first axial protrusion 60 is formed as a single component integrated with the sprocket body 50 around the at least one lightweight hole 62. In this modified example, the at least one axial protrusion is a second axial protrusion 64. For example, in the example shown in Figure 10, the rear sprocket 42 does not have a first axial protrusion 60.

[0057] Alternatively, at least one of the rear sprockets 42 other than the largest sprocket 42A may have at least one of the first axial direction protrusion 60 and the second axial direction protrusion 64.

[0058] Alternatively, the second axial protrusion 64 may not be formed around some of the plurality of lightweight holes 62. That is, the second axial protrusion 64 may be formed around at least a portion of the lightweight holes 62 of the rear sprocket 42.

[0059] The term "at least one" as used in this specification means "more than one" of the required options. As an example, if there are two options, "at least one" as used in this specification means "only one option" or "both options". As another example, if there are three or more options, "at least one" as used in this specification means "only one option" or "any combination of two or more options".

[0060] 10: Human-powered vehicle 30: Rear wheel hub assembly 34: Sprocket support body 40: Rear sprocket assembly 42: Rear sprocket 42A: Maximum sprocket 44: Sprocket Carrier 50: Sprocket body 52: Outer surface in the axial direction 54: Inner side surface in the axial direction 56: Radial inner circumference 58: Installation Department 60: Protrusion in the first axis direction 60A: Near end 60B: Free distal end 62: Lightweight Hole Section 64: Protrusion in the second axis direction 64A: Near end 64B: Free distal end 70: Sprocket teeth 72: Downshifting promotes gear development 74: Upshifting promotion gear AD: Axis direction CA: Center of rotation axis CS: Center plane in the axial direction

Claims

1. A rear sprocket, which can be mounted on a rear wheel hub assembly of a manually driven vehicle; comprising: a sprocket body, a plurality of sprocket teeth, and at least one first axial direction protrusion; the sprocket body having: an axial direction outer surface, an axial direction inner surface, a radial inner periphery, and at least one mounting portion; the axial direction inner surface is disposed on the opposite side of the axial direction outer surface in the axial direction relative to the rotation center axis of the rear sprocket; the radial inner periphery, in an installation state in which the rear sprocket assembly including the rear sprocket is mounted on the rear wheel hub assembly, is away from the sprocket support of the rear wheel hub assembly; the at least one mounting portion is mounted on a sprocket carrier of the rear sprocket assembly and one of the other rear sprockets of the rear sprocket assembly; the axial direction inner surface, in the installation state, faces the axial direction center plane of the manually driven vehicle in the axial direction; the plurality of sprocket teeth extend radially outward from the outer periphery of the sprocket body in the radial direction relative to the rotation center axis; The aforementioned at least one first axial direction protrusion is formed as a single component integrated with the aforementioned sprocket body and in the aforementioned radial inner circumference; the aforementioned at least one first axial direction protrusion has: a proximal end and a free distal end; the aforementioned proximal end is integrally connected to the aforementioned sprocket body; the aforementioned free distal end, in the assembled state of the aforementioned rear sprocket assembly, does not contact other rear sprockets of the aforementioned rear sprocket assembly; the aforementioned at least one first axial direction protrusion extends from the aforementioned axial direction inner surface toward the aforementioned axial direction and away from the aforementioned axial direction outer surface in the aforementioned radial inner circumference; the aforementioned at least one first axial direction protrusion extends continuously in the circumferential direction relative to the aforementioned rotation center axis, covering at least one-sixth of the entire circumference of the aforementioned radial inner circumference.

2. As in request item 1, the rear sprocket, where, In the aforementioned assembly state of the rear sprocket assembly, the rear sprocket is arranged outward in the axial direction from the largest sprocket of the rear sprocket assembly.

3. The rear sprocket as in request item 1 or 2, wherein, The aforementioned at least one first axial protrusion extends continuously in the aforementioned circumferential direction, covering at least one-quarter of the entire circumference of the aforementioned radial inner circumference.

4. As in request item 3, the rear sprocket, where, The aforementioned at least one first axial protrusion extends continuously in the aforementioned circumferential direction, covering at least half of the entire circumference of the aforementioned radial inner circumference.

5. As in request item 4, the rear sprocket, where, The aforementioned at least one first axial protrusion extends continuously in the aforementioned circumferential direction, covering the entire circumference of the aforementioned radial inner circumference.

6. As in request item 5, the rear sprocket, wherein, At least one of the aforementioned protrusions along the first axis is non-circular.

7. The rear sprocket as requested in item 1 or 2, wherein, It further includes at least one second axial protrusion, which extends around at least one lightweight hole formed in the sprocket body.

8. The rear sprocket as requested in item 1 or 2, wherein, The aforementioned plurality of sprocket teeth includes at least one of: at least one downshifting facilitator tooth and at least one upshifting facilitator tooth.

9. As in request item 8, the rear sprocket, wherein, The aforementioned at least one protrusion in the first axial direction, when viewed from the aforementioned axial direction, overlaps with at least one of the aforementioned downshifting facilitator teeth and at least one of the aforementioned upshifting facilitator teeth in the aforementioned circumferential direction.

10. A rear sprocket, which can be mounted on a rear wheel hub assembly of a manually driven vehicle, comprises: a sprocket body, a plurality of sprocket teeth, and at least one axially oriented protrusion; the sprocket body has: an axially oriented outer surface, an axially oriented inner surface disposed on the opposite side of the axially oriented outer surface in the axial direction relative to the rotation center axis of the rear sprocket, and at least one lightweight hole; the axially oriented inner surface, in an installation state in which the rear sprocket assembly including the rear sprocket is mounted on the rear wheel hub assembly, faces the axially oriented center surface of the manually driven vehicle in the axial direction; the plurality of sprocket teeth extend radially outward from the outer periphery of the sprocket body in the radial direction relative to the rotation center axis; the at least one axially oriented protrusion is formed as a single component integrated with the sprocket body and is formed around the at least one lightweight hole; the at least one axially oriented protrusion has a free distal end; the free distal end, in the assembled state of the rear sprocket assembly, does not contact other rear sprockets in the rear sprocket assembly.

11. The rear sprocket as in request item 10, wherein, The aforementioned at least one axially oriented protrusion extends from the inner axially oriented side toward the axially oriented side and away from the outer axially oriented side.

12. The rear sprocket as requested in item 10 or 11, wherein, The aforementioned at least one axially oriented protrusion has a proximal end; the aforementioned proximal end is integrally connected to the aforementioned sprocket body.

13. The rear sprocket as requested in item 10 or 11, wherein, The aforementioned at least one axial protrusion completely surrounds the aforementioned at least one lightweight hole.

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