JP2017071380A - Sprocket for bicycle and sprocket assembly for bicycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sprocket for a bicycle, which is high in chain holding force and has excellent productivity.SOLUTION: A sprocket 14 for a bicycle has a rotation center axis X. The sprocket 14 comprise first teeth 32a and second teeth 32b. The first teeth 32a have a first axial chain engagement width. The first axial chain engagement width W1 is smaller than a first axial interval L1 in an outer link. The first axial chain engagement width W1 is larger than a second axial interval L2 in an inner link plate 2b which is connected to an outer link plate 2a. The second teeth 32b have a second axial chain engagement width W4. The second axial chain engagement width W4 is smaller than the second axial interval L2. The second teeth 32b are formed by deformation of a material.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a bicycle sprocket and a bicycle sprocket assembly.

  A conventional bicycle sprocket is provided on each of the crank assembly and the rear wheel. A chain is meshed between the sprocket of the crank assembly and the sprocket of the rear wheel. Thereby, the rotation of the crank assembly is transmitted to the rear wheel via the chain.

  In the chain, inner link plates and outer link plates are alternately connected. The distance between the pair of inner link plates facing each other is smaller than the distance between the pair of outer link plates facing each other. For this reason, when the sprocket teeth are formed so that the thicknesses (engagement widths) of the sprocket teeth are all the same, the gap between the outer link plate and the sprocket teeth in the direction of the sprocket thickness is the inner link plate. And larger than the gap between the sprocket teeth.

  In such a conventional structure, the engagement between the chain and the sprocket tends to be loosened by the gap between the outer link plate and the sprocket teeth in the thickness direction of the sprocket. Therefore, a sprocket has been proposed in which the thickness of the teeth meshing with the outer link plate is larger than the thickness of the teeth meshing with the inner link plate (see Patent Document 1).

US2013 / 0139642

  In the conventional sprocket, by cutting the teeth that mesh with the inner link plate, the thickness of the teeth that mesh with the outer link plate is made larger than the thickness of the teeth that mesh with the inner link plate (see, for example, US2013 / 0139642) (See paragraph 0045).

  In this case, since the sprocket is formed, there is a problem that the processing time becomes long at the time of cutting. That is, when producing the sprocket, it has been difficult to improve the sprocket productivity.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a bicycle sprocket having high chain holding power and excellent productivity. Another object of the present invention is to provide a bicycle sprocket assembly having high chain holding power and excellent productivity.

  (1) A bicycle sprocket according to one aspect of the present invention has a rotation center axis. The bicycle sprocket includes first teeth and second teeth. The first tooth has a first axial chain engagement width. The first axial chain engagement width is smaller than the first axial interval in the outer link of the bicycle chain. Further, the first axial chain engagement width is larger than the second axial interval in the inner link connected to the outer link. The second tooth has a second axial chain engagement width. The second axial chain engagement width is smaller than the second axial spacing. The second tooth is formed by deformation of the material.

  In this sprocket, the first axial chain engagement width of the first teeth is smaller than the first axial interval in the outer link and larger than the second axial interval in the inner link. Further, the second axial chain engagement width of the second teeth is smaller than the second axial interval. Thereby, a chain can be reliably hold | maintained with a sprocket. Further, since the second teeth are formed by deformation of the material, the productivity of the sprocket can be improved as compared with the conventional technique.

  (2) A bicycle sprocket according to another aspect of the present invention may be configured as follows. The second tooth is formed by press working.

  In this case, since the second teeth are formed by press working, the productivity of the sprocket can be reliably improved.

  (3) A bicycle sprocket according to another aspect of the present invention may be configured as follows. The first tooth has a recess. The recess is for avoiding excessive interference with the inner link, and is formed by pressing.

  In this case, even if the first teeth are disposed between the outer links, excessive interference with the inner links can be avoided by the recesses. Moreover, since the recess is formed by press working, the productivity of the recess can be improved.

  (4) A bicycle sprocket according to another aspect of the present invention may be configured as follows. The first tooth has a recess. The recess is for avoiding excessive interference with the inner link, and is formed by cutting.

  In this case, even if the first teeth are disposed between the outer links, excessive interference with the inner links can be avoided by the recesses. Moreover, since a recessed part is formed by cutting, a recessed part can be formed correctly.

  (5) A bicycle sprocket according to another aspect of the present invention may be configured as follows. The first tooth has a main body portion and an additional portion. The additional portion is attached to the main body portion in order to increase the width of the main body portion. The first axial chain engagement width is a width obtained by attaching the additional portion to the main body portion.

  In this case, since the first tooth has the first axial chain engagement width larger than the second axial interval by attaching the additional portion to the main body portion, the material of the additional portion can be freely selected.

  (6) A bicycle sprocket according to another aspect of the present invention may be configured as follows. The additional portion of the first tooth is made of metal. This additional portion is attached to the first tooth by bonding, diffusion bonding, caulking, or casting.

  In this case, since the additional portion of the first tooth is made of metal, the strength and rigidity of the additional portion can be sufficiently secured. Moreover, this additional part can be reliably attached to the first tooth by adhesion, diffusion bonding, caulking, or casting.

  (7) A bicycle sprocket according to another aspect of the present invention may be configured as follows. The additional portion of the first tooth is made of nonmetal. This additional portion is attached to the first tooth by bonding or integral molding.

  In this case, since the additional portion of the first tooth is made of a non-metal, it is possible to facilitate molding and reduce the weight of the additional portion. Moreover, this additional part can be reliably attached to a 1st tooth | gear by adhesion | attachment or integral molding.

  (8) A bicycle sprocket according to another aspect of the present invention may be configured as follows. Each of the first tooth and the second tooth has a drive surface. The drive surface includes a contact point with which the chain roller contacts. A drive surface extension is formed on the drive surface. The drive surface extending portion extends in the circumferential direction on the radially outer side from the contact point.

  In this case, in each of the first tooth and the second tooth, the driving surface extending portion of the driving surface extends in the circumferential direction on the radially outer side from the contact point of the driving surface. For this reason, the movement to the radial direction outer side of the chain of a sprocket can be suppressed reliably.

  (9) A bicycle sprocket according to another aspect of the present invention may be configured as follows. Each of the first tooth and the second tooth has a non-driving surface. A non-driving surface extending portion is formed on the non-driving surface. The non-driving surface extending portion extends in the circumferential direction in order to suppress the movement of the chain roller to the radially outer side.

  In this case, the movement of the chain to the outside in the radial direction can be reliably suppressed by the non-driving surface extending portions of the non-driving surfaces of the first teeth and the second teeth.

  (10) A bicycle sprocket according to another aspect of the present invention may be configured as follows. Each of the first tooth and the second tooth has a drive surface and a non-drive surface. The drive surface includes a contact point with which the chain roller contacts. A drive surface extension is formed on the drive surface. The drive surface extending portion extends in the circumferential direction on the radially outer side from the contact point. Further, a non-driving surface extending portion is formed on the non-driving surface. The non-driving surface extending portion extends in the circumferential direction in order to suppress the movement of the chain roller to the radially outer side.

  In this case, in each of the first tooth and the second tooth, the driving surface extending portion of the driving surface extends in the circumferential direction on the radially outer side from the contact point of the driving surface. For this reason, the movement of the chain roller to the outer side in the radial direction can be reliably suppressed by the non-driving surface extending portions of the non-driving surfaces of the first teeth and the second teeth.

  (11) A bicycle sprocket according to another aspect of the present invention may be configured as follows. The bicycle sprocket further includes a shift region for shifting the chain at the time of shifting.

  In this case, a shiftable bicycle sprocket excellent in chain holding force can be provided.

  (12) A bicycle sprocket according to another aspect of the present invention may be configured as follows. The bicycle sprocket further includes a metallic annular portion and a non-metallic main body portion. In the metal annular portion, the first teeth and the second teeth are provided on the outer periphery. The non-metallic body portion is attached to the radially inner periphery of the metallic annular portion.

  In this case, since the sprocket body is made of non-metal, the sprocket can be reduced in weight. Moreover, since the annular part and the first and second teeth of the sprocket are made of metal, the strength and rigidity of the part where the sprocket engages with the chain can be improved.

  (13) A bicycle sprocket according to another aspect of the present invention may be configured as follows. In the bicycle sprocket, the pressing process is forging.

  In this case, since the press work is forging, the productivity of the sprocket can be reliably and easily improved.

  (14) A bicycle sprocket according to another aspect of the present invention may be configured as follows. The second tooth is formed by pressing and cutting processes. Even if the second teeth are formed in this way, the productivity of the sprocket can be improved.

  (15) A bicycle sprocket according to another aspect of the present invention may be configured as follows. The second teeth are formed by a first pressing step, a cutting step after the first pressing step, and a second pressing step after the cutting step. Thus, even if the second teeth are formed stepwise, the productivity of the sprocket can be improved.

  (16) A bicycle sprocket according to another aspect of the present invention may be configured as follows. The second tooth has a first surface and a second surface located on the opposite side of the first surface in the axial direction parallel to the rotation center axis. The first pressing step is a step of pressing the first surface side of the second tooth. The second pressing step is a step of pressing the second surface side of the second tooth. By forming the second teeth in this way, both surfaces (first surface and second surface) of the second teeth can be easily formed. That is, the productivity of the sprocket can be improved.

  (17) A bicycle sprocket according to another aspect of the present invention may be configured as follows. The cutting step is a step of cutting the protruding portion protruding in the axial direction by the first pressing step on the second surface side of the second tooth. By forming the second teeth in this way, the second surface of the second teeth can be easily formed into a shape in the second pressing step. That is, the productivity of the sprocket can be improved.

  (18) A bicycle sprocket according to one aspect of the present invention has a rotation center axis. The bicycle sprocket includes first teeth and second teeth. The first tooth has a first axial chain engagement width. The first axial chain engagement width is smaller than the first axial interval in the outer link of the bicycle chain. Further, the first axial chain engagement width is larger than the second axial interval in the inner link connected to the outer link. The second tooth has a second axial chain engagement width. The second axial chain engagement width is smaller than the second axial spacing. The first tooth has a substantially octagonal shape when viewed from the outside in the radial direction.

  In this sprocket, the first axial chain engagement width of the first teeth is smaller than the first axial interval in the outer link and larger than the second axial interval in the inner link. Further, the second axial chain engagement width of the second teeth is smaller than the second axial interval. Thereby, a chain can be reliably hold | maintained with a sprocket.

  Further, since the first tooth has a substantially octagonal shape when viewed from the outside in the radial direction, excessive interference between the first tooth and the inner link plate can be avoided, and the outer link plate can be The tooth shape to be reliably held can be easily formed by press work, for example, forging.

  (19) A bicycle sprocket according to one aspect of the present invention has a rotation center axis. The bicycle sprocket includes first teeth and second teeth. The first tooth has a first axial chain engagement width. The first axial chain engagement width is smaller than the first axial interval in the outer link of the bicycle chain. Further, the first axial chain engagement width is larger than the second axial interval in the inner link connected to the outer link. The second tooth has a second axial chain engagement width. The second axial chain engagement width is smaller than the second axial spacing. The first tooth has an inclined portion for avoiding excessive interference with the inner link.

  In this sprocket, the first axial chain engagement width of the first teeth is smaller than the first axial interval in the outer link and larger than the second axial interval in the inner link. Further, the second axial chain engagement width of the second teeth is smaller than the second axial interval. Thereby, a chain can be reliably hold | maintained with a sprocket.

  In addition, since the first tooth has an inclined portion, even if the first tooth is disposed between the outer links, the inclined portion can avoid excessive interference with the inner link, and the outer link. A tooth shape that reliably holds the plate can be easily formed by press work, for example, forging.

  (20) A bicycle sprocket according to another aspect of the present invention may be configured as follows. The first tooth further includes a first surface, a second surface, and a third surface. The third surface extends in the circumferential direction between the axial direction of the first surface and the second surface. The inclined portion has a first chamfered surface, a second chamfered surface, a third chamfered surface, and a fourth chamfered surface.

  The first chamfered surface is formed from the first surface to the third surface on the driving side. The second chamfered portion is formed from the second surface to the third surface on the driving side. The third chamfered surface is formed from the first surface to the third surface on the non-driving side. The fourth chamfered surface is formed from the second surface to the third surface on the non-driving side.

  In this case, excessive interference between the first teeth and the inner link plate can be avoided by the first to fourth chamfered surfaces, and the tooth shape for securely holding the outer link plate can be obtained by pressing, for example, forging. It can be formed easily.

  (21) A bicycle sprocket according to another aspect of the present invention may be configured as follows. The first axial contact width at which the drive surface of the first tooth contacts the chain roller is formed to be substantially the same length as the second axial contact width at which the drive surface of the second tooth contacts the chain roller.

  In this case, since the first axial contact width and the second axial contact width are substantially the same length, the driving force can be stably transmitted from the sprocket to the chain.

  (22) A bicycle sprocket according to one aspect of the present invention has a rotation center axis. The bicycle sprocket includes first teeth and second teeth. The first tooth has a first axial chain engagement width. The first axial chain engagement width is smaller than the first axial interval in the outer link of the bicycle chain. Further, the first axial chain engagement width is larger than the second axial interval in the inner link connected to the outer link. The second tooth has a second axial chain engagement width. The second axial chain engagement width is smaller than the second axial spacing. At least one of the first tooth and the second tooth has a plating layer.

  In this sprocket, the first axial chain engagement width of the first teeth is smaller than the first axial interval in the outer link and larger than the second axial interval in the inner link. Further, the second axial chain engagement width of the second teeth is smaller than the second axial interval. Thereby, a chain can be reliably hold | maintained with a sprocket.

  In addition, since at least one of the first tooth and the second tooth has a plating layer, it is possible to improve the wear resistance and rust prevention of at least one of the first tooth and the second tooth.

  (23) A bicycle sprocket according to another aspect of the present invention may be configured as follows. The first and second teeth are made of aluminum. The plating layer is a nickel plating layer. In this case, the wear resistance of the first tooth and the second tooth can be improved.

  (24) A bicycle sprocket according to another aspect of the present invention may be configured as follows. The first tooth and the second tooth are made of iron. The plating layer is a nickel chrome plating layer. In this case, the antirust property of the first tooth and the second tooth can be improved.

  (25) A bicycle sprocket assembly according to another aspect of the present invention includes the sprocket according to any one of (1) to (24).

  This sprocket assembly can obtain the same effects as the effects described in (1) to (24) above.

  (26) A bicycle sprocket assembly according to another aspect of the present invention may be configured as follows. In this sprocket assembly, the sprocket is a single front sprocket.

  Even if the sprocket assembly is configured in this manner, the same effects as described in the above (1) to (24) can be obtained.

  (27) A bicycle sprocket assembly according to another aspect of the present invention may be configured as follows. In this sprocket assembly, the sprocket is a plurality of front sprockets.

  Even if the sprocket assembly is configured in this manner, the same effects as described in the above (1) to (24) can be obtained.

  (28) A bicycle sprocket assembly according to another aspect of the present invention may be configured as follows. In the present sprocket assembly, the sprocket is movable along the rotation center axis.

  Even if the sprocket assembly is configured in this manner, the same effects as described in the above (1) to (24) can be obtained.

  (29) A bicycle sprocket assembly according to another aspect of the present invention may be configured as follows. In this sprocket assembly, the sprocket is a rear sprocket.

  Even if the sprocket assembly is configured in this manner, the same effects as described in the above (1) to (24) can be obtained.

  According to the present invention, it is possible to provide a bicycle sprocket having a high chain holding force and excellent productivity. In addition, a bicycle sprocket assembly having a high chain holding force and excellent productivity can be provided.

The front view of the crank assembly for bicycles by the 1st and 2nd embodiment of the present invention. The front perspective view of the 1st sprocket by a 1st embodiment. The rear view of the 1st sprocket by a 1st embodiment. The rear perspective fragmentary view of the 1st and 2nd sprocket by 1st Embodiment. The side surface partial view which looked at the 1st sprocket and 2nd sprocket by 1st Embodiment from the radial direction outer side. The front perspective view of the 2nd sprocket by 1st Embodiment. Sectional drawing of the 3rd tooth of the 1st tooth of the 1st sprocket and the 2nd sprocket by a 2nd embodiment of the present invention. The front view of the 1st tooth of the 1st sprocket and the 3rd tooth of the 2nd sprocket by other embodiments of the present invention. The partial front view of the tooth | gear part of the 1st and 2nd sprocket by other embodiment of this invention. The side surface partial view which looked at the tooth | gear part of the 1st and 2nd sprocket by other embodiment of this invention from the radial direction outer side. The front view of the 1st sprocket by other embodiments of the present invention. The front view of the 1st sprocket by other embodiments of the present invention. The fragmentary sectional view of the 1st sprocket by other embodiments of the present invention. The schematic diagram for demonstrating the formation form of the 2nd tooth and 4th tooth | gear by other embodiment of this invention.

<First Embodiment>
As shown in FIG. 1, a bicycle crank assembly 10 (hereinafter referred to as a crank assembly) according to a first embodiment includes a crank arm 12, a first sprocket 14 (an example of a bicycle sprocket), and a second sprocket. 16 (an example of a bicycle sprocket). The first sprocket 14 and the second sprocket 16 are an example of a bicycle sprocket assembly.

  In the crank assembly 10, the first sprocket 14 and the second sprocket 16 are front sprockets that can be engaged with the chain 2. The second sprocket 16 has fewer teeth than the first sprocket 14. The chain 2 includes a pair of outer link plates 2a, a pair of inner link plates 2b, and a pair of outer link plates 2a and a chain roller 2c that couples the pair of inner link plates 2b.

<Crank arm>
The crank arm 12 is connected to the crankshaft 19 so as to be integrally rotatable. The crank arm 12 includes a sprocket mounting portion 20 and an arm portion 22 provided integrally with or separate from the sprocket mounting portion 20.

  The sprocket mounting portion 20 has a plurality (for example, four) of sprocket mounting arms 24. The plurality of sprocket mounting arms 24 are arranged at intervals in the circumferential direction. The intervals in the circumferential direction of the sprocket mounting arm 24 are equal intervals. Here, an example in which the circumferential intervals of the sprocket mounting arms 24 are equal is shown, but the circumferential intervals of the sprocket mounting arms 24 may be unequal intervals.

  The sprocket mounting arm 24 includes a first mounting portion 24a and a second mounting portion 24b. The first attachment portion 24 a is for attaching the first sprocket 14. The first mounting portion 24 a is formed at the tip of the sprocket mounting arm 24. The first attachment portion 24a is, for example, a through hole. The first sprocket 14 is fixed to the first mounting portion 24a.

  The second attachment portion 24 b is for attaching the second sprocket 16. The second mounting portion 24b is formed at the proximal end portion of the sprocket mounting arm 24 on the radially inner side from the first mounting portion 24a. The second attachment portion 24b is, for example, a bottomed screw hole. The second sprocket 16 is fixed to the second mounting portion 24b.

  The arm portion 22 is formed integrally with or separately from the sprocket mounting portion 20. Here, the arm portion 22 is formed integrally with the sprocket mounting portion 20. A pedal attachment portion 22 a is provided at the distal end portion of the arm portion 22. A pedal (not shown) can be attached to the pedal mounting portion 22a. A connecting hole 22 b is provided at the base end portion of the arm portion 22. The crankshaft 19 is coupled to the coupling hole 22b so as to be integrally rotatable.

<First sprocket>
As shown in FIGS. 2 to 5, the first sprocket 14 has a rotation center axis X. The first sprocket 14 includes a first sprocket body 30 (an example of a main body part), a first annular part 31 (an example of an annular part), and a plurality of teeth 32 (an example of a first tooth part and a second tooth part). The first speed change area 34 (see FIGS. 3 and 4; an example of the speed change area).

  The first sprocket body 30 is made of non-metal, for example, synthetic resin such as carbon fiber reinforced resin. The first procket body 30 is formed integrally with the first annular portion 31. As shown in FIGS. 2 to 4, the first sprocket main body 30 has a plurality of (for example, four) first fixing portions 30 a. The plurality of first fixing portions 30a are arranged at intervals in the circumferential direction.

  Each 1st fixing | fixed part 30a is a through-hole, for example. Each 1st fixing | fixed part 30a is arrange | positioned in the position facing each 1st attaching part 24a. In this state, the first fixing bolts 26 (see FIG. 1) are inserted through the first fixing portions 30a and the first attachment portions 24a and screwed into nut members (not shown). As a result, the first sprocket body 30 is fixed to the sprocket mounting arm 24.

  The first annular portion 31 is attached to the first sprocket body 30. Specifically, the first annular portion 31 is attached to the outer periphery of the first sprocket body 30. The first annular portion 31 is made of metal, for example, aluminum, titanium, or iron / stainless steel. A plurality of teeth 32 are provided on the outer periphery of the first annular portion 31.

  A plurality of teeth 32 (including first teeth 32 a and second teeth 32 b described later) are provided on the outer periphery of the first annular portion 31. Specifically, the plurality of teeth 32 (for example, 30 to 60) are arranged side by side in the circumferential direction on the outer periphery of the first annular portion 31, and are integrally formed on the outer peripheral portion of the first annular portion 31. The plurality of teeth 32 are made of metal, for example, aluminum, titanium, or iron / stainless steel.

  The plurality of teeth 32 include a plurality of first teeth 32a (an example of first teeth) and a plurality of second teeth 32b (an example of second teeth). The first teeth 32a and the second teeth 32b are arranged alternately in the circumferential direction, that is, adjacent to each other in the circumferential direction.

  The first teeth 32a are formed to be engageable with the outer link plate 2a. Specifically, the first teeth 32a are formed so as to be engageable between the axial directions of the pair of outer link plates 2a. The first teeth 32a are formed in a tapered shape so that the axial width gradually decreases toward the radially outer side. The axial direction includes a direction in which the rotation center axis X extends and a direction parallel to the rotation center axis X. The axial direction used here corresponds to a direction parallel to the rotation center axis X.

  As shown in FIG. 4, the first tooth 32a preferably has a first recess 32e (an example of a recess). The 1st recessed part 32e is provided in the corner part of the 1st tooth | gear 32a. The surface on the first side surface 14a side in the first recess 32e is preferably formed flush with the surface on the first side surface 14a side in the second tooth 32b. The surface of the first recess 32e on the second side surface 14b side is preferably formed flush with the surface of the second tooth 32b on the second side surface 14b side.

  Here, the first side surface 14a (see FIG. 1) is a front surface arranged on the outer side in the axial direction far from the bicycle frame when the crank assembly 10 is mounted on the bicycle. The second side surface 14b (see FIGS. 3 and 4) is a back surface arranged on the inner side in the axial direction near the bicycle frame.

  The first recess 32e is formed by press work such as forging. Here, although the example in case the 1st recessed part 32e is formed by press work is shown, the 1st recessed part 32e may be formed by cutting.

  As shown in FIG. 5, the first recess 32e is formed to face the end of the inner link plate 2b. Excessive interference between the first teeth 32a and the inner link plate 2b is avoided by the first recess 32e. Further, by providing the first recess 32e in the first tooth 32a, as shown in FIGS. 2, 4, and 5, the first tooth 32a (except for the first teeth 32a1 and 32a2 for shifting) has a diameter. When viewed from the outside in the direction, it is formed in a substantially + (plus) shape.

  Here, as shown in FIGS. 2 to 3, the plurality of first teeth 32 a include a plurality of (for example, two) first gear teeth 32 a 1 and a plurality of (for example, two) first gears for shifting. Teeth 32a2 are included. The first gear 32a1 for shifting is used for the downward shifting in which the chain 2 moves from the first sprocket 14 to the second sprocket 16. The first gear 32a2 for shifting is for the upward shifting in which the chain 2 moves from the second sprocket 16 to the first sprocket 14. The first gear 32a1 for shifting and the first tooth 32a2 for shifting are preferably formed in a substantially T shape when viewed from the outside in the radial direction by providing the first recess 32e as described above. .

  As shown in FIG. 5, the first tooth 32a has a first maximum axial width W1 (an example of a first axial chain engagement width). The first maximum axial width W1 is the width of the longest portion of the first tooth 32a in the axial direction. The first maximum axial width W1 is smaller than the first axial interval L1 in the pair of outer link plates 2a. The first maximum axial width W1 is larger than the second axial interval L2 in the pair of inner link plates 2b.

  The first axial interval L1 is the interval between the surfaces of the pair of outer link plates 2a facing each other in the axial direction. The second axial interval L2 is the interval between the surfaces of the pair of inner link plates 2b facing each other in the axial direction.

  As shown in FIGS. 2 to 4, the second teeth 32 b are formed to be engageable with the inner link plate 2 b. Specifically, the second teeth 32b are formed to be engageable between the axial directions of the pair of inner link plates 2b.

  The second teeth 32b are preferably formed in a substantially-(minus) shape when viewed from the radially outer side. The second teeth 32b are formed in a tapered shape so that the axial width gradually decreases toward the radially outer side.

  As shown in FIG. 5, the second teeth 32b have a second maximum axial width W2 (an example of a second axial chain engagement width). The second maximum axial width W2 is the width of the longest portion of the second tooth 32b in the axial direction. The second maximum axial width W2 is smaller than the second axial interval L2. The second maximum axial width W2 is smaller than the first maximum axial width W1.

  By processing the second teeth 32b as follows, the second teeth 32b are formed, and the above configuration is satisfied. The second teeth 32b are formed by deformation of the material. Specifically, the second teeth 32b are formed by pressing. More specifically, the second teeth 32b are formed by forging. Specifically, the second tooth 32b is formed by forging together with the first recess 32e. In this way, the second maximum tooth width W2 of the second tooth 32b is set by pressing the second tooth 32b, for example, forging.

  The first shift region 34 is provided for shifting the chain 2. The first speed change region 34 is a region in which the chain engages with the teeth 32 of the first sprocket 14 during the upshift operation from the second sprocket 16 to the first sprocket 14. The first shift region 34 is a region in which the chain is separated from the teeth 32 of the first sprocket 14 during a downward shift operation from the first sprocket 14 to the second sprocket 16.

  As shown in FIGS. 2 to 4, the first speed change region 34 includes a plurality of first speed change teeth 32 c. Here, a plurality of (for example, two) first gears 32a1 for shifting correspond to the first gears 32c. Further, two second teeth 32b adjacent to the first teeth 32a1 for each shift correspond to the first shift teeth 32c.

  As shown in FIGS. 2 and 3, the first speed change gear 32c has a first guide surface 32d. The first guide surface 32 d is for guiding the chain 2. The first guide surface 32d is provided on the first speed change gear 32c on the first side surface 14a (see FIG. 2) side or the second side surface 14b (see FIGS. 3 and 4) side of the first sprocket 14. The first guide surface 32d is formed in a concave shape so that the thickness gradually decreases toward the side portion of the first speed change gear 32c.

The first speed change region 34 preferably includes a first protrusion 36a and a second protrusion 36b.
The first protrusion 36a and the second protrusion 36b are provided on the first sprocket body 30 so as to be able to support the chain 2. Here, the pair of first protrusions 36a and the second protrusions 36b are arranged at intervals in the circumferential direction.

  The first protrusion 36 a is provided to protrude from the second side surface 14 b of the first sprocket body 30 in order to guide the chain 2 to the teeth 32 of the first sprocket 14. For example, the first protrusion 36a guides the chain 2 to the second teeth 32b indicated by hatching in FIG. The second protrusion 36b is provided to protrude from the second side surface 14b of the first sprocket body 30 in order to guide the chain 2 to the first protrusion 36a.

  Further, as shown in FIGS. 3 and 4, the first shift region 34 includes a stepped portion 38. The step portion 38 is for facilitating engagement of the chain 2 supported by the first protrusion 36 a with the teeth 32 of the first sprocket 14. The stepped portion 38 is provided radially inward from the bottom of the plurality of teeth 32 on the first side surface 14a. Further, the stepped portion 38 is provided on the downstream side in the traveling rotation direction R with respect to the first protrusion 36a. The stepped portion 38 is formed to be recessed in a substantially triangular shape.

<Second sprocket>
As shown in FIGS. 4 and 6, the second sprocket 16 has a rotation center axis Y. The rotation center axis Y is concentric with the rotation center axis X. The second sprocket 16 includes a second sprocket body 40 (an example of a main body part), a second annular part 41 (an example of an annular part), and a plurality of teeth 42 (an example of a first tooth part and a second tooth part). , A second shift region 44 (an example of a shift region).

  The second sprocket body 40 is made of metal, for example, aluminum, titanium, or iron / stainless steel. The second sprocket body 40 has a plurality of (for example, four) second fixing portions 40a. The plurality of second fixing portions 40a are arranged at intervals in the circumferential direction.

  Each 2nd fixing | fixed part 40a is a through-hole, for example. Each 2nd fixing | fixed part 40a is arrange | positioned in the position facing each 2nd attaching part 24b. In this state, the second fixing bolt 28 is inserted into each of the second fixing portions 40a and the second mounting portion 24b, and the second fixing bolt 28 is screwed into a nut member (not shown). As a result, the second sprocket body 40 is fixed to the sprocket mounting arm 24.

  The second annular portion 41 is provided on the outer periphery of the second sprocket body 40. The second annular portion 41 is made of metal, for example, aluminum, titanium, or iron / stainless steel. A plurality of teeth 42 are provided on the outer periphery of the second annular portion 41.

  A plurality of teeth 42 (including third teeth 42 a and fourth teeth 42 b described later) are provided on the outer periphery of the second annular portion 41. Specifically, the plurality of teeth 42 (for example, 20 to 40) are arranged side by side in the circumferential direction on the outer periphery of the second annular portion 41, and are integrally formed on the outer peripheral portion of the second annular portion 41. The plurality of teeth 42 are made of metal, for example, aluminum, titanium, or iron / stainless steel.

  The plurality of teeth 42 include a plurality of third teeth 42a (an example of first teeth) and a plurality of fourth teeth 42b (an example of second teeth). The third teeth 42a and the fourth teeth 42b are arranged alternately in the circumferential direction, that is, adjacent to each other in the circumferential direction.

  The third teeth 42a are formed to be engageable with the outer link plate 2a. Specifically, the third teeth 42a are formed to be engageable between the axial directions of the pair of outer link plates 2a. The third teeth 42a are formed in a tapered shape so that the axial width gradually decreases toward the radially outer side.

  As shown in FIG. 6, the third tooth 42a has a second recess 42e (an example of a recess). The 2nd recessed part 42e is provided in the corner part of the 3rd tooth | gear 42a. The surface of the second recess 42e on the first side surface 14a side is formed flush with the surface of the fourth tooth 42b on the first side surface 14a side. The surface on the second side surface 14b side in the second recess 42e is formed flush with the surface on the second side surface 14b side in the second tooth 32b.

  The second recess 42e is formed by press work such as forging. Here, an example in which the second recess 42e is formed by pressing is shown, but the second recess 42e may be formed by cutting.

  Similar to the first recess 32e described above, the second recess 42e is formed to face the end of the inner link plate 2b. Excessive interference between the third teeth 42a and the inner link plate 2b is avoided by the second recess 42e. Further, by providing the second recess 42e in the third tooth 42a, as shown in FIGS. 4 and 6, the third tooth 42a is formed in a substantially + (plus) shape when viewed from the outside in the radial direction. The

  As shown in FIG. 5, the third teeth 42a have a third maximum axial width W3 (an example of a first axial chain engagement width). The third maximum axial width W3 is the width of the portion in which the length of the third tooth 42a is the longest in the axial direction. The third maximum axial width W3 is smaller than the first axial interval L1. The third maximum axial width W3 is larger than the second axial interval L2 in the pair of inner link plates 2b.

  As shown in FIGS. 4 to 6, the fourth teeth 42b are formed so as to be engageable with the inner link plate 2b. Specifically, the fourth teeth 42b are formed to be engageable between the axial directions of the pair of inner link plates 2b.

  The fourth teeth 42b are formed in a substantially-(minus) shape when viewed from the outside in the radial direction. The fourth teeth 42b are formed in a tapered shape so that the axial width gradually decreases toward the radially outer side.

  As shown in FIG. 5, the fourth tooth 42b has a fourth maximum axial width W4 (an example of a second axial chain engagement width). The fourth maximum axial direction width W4 is the width of the longest portion of the fourth tooth 42b in the axial direction. The fourth maximum axial width W4 is smaller than the second axial interval L2. The fourth maximum axial width W4 is smaller than the third maximum axial width W3.

  By processing the fourth teeth 42b as follows, the fourth teeth 42b are formed so that the above-described configuration is satisfied. The fourth teeth 42b are formed by deformation of the material. Specifically, the fourth teeth 42b are formed by pressing. More specifically, the fourth teeth 42b are formed by forging. As described above, the fourth tooth 42b is press-formed, for example, forged to set the fourth maximum axial width W4 of the fourth tooth 42b.

  The second shift region 44 is provided for shifting the chain 2. The second shift region 44 is configured so that the chain is connected to the teeth 42 of the first sprocket 14 during the upward shift operation from the second sprocket 16 to the first sprocket 14 or during the downward shift operation from the first sprocket 14 to the second sprocket 16. Or a region away from the teeth 42 of the first sprocket 14.

  The second shift region 44 includes a plurality of (for example, two) second shift teeth 42c. The second transmission teeth 42c are provided at intervals in the circumferential direction. The second speed change gear 42c has a second guide surface 42d. The second guide surface 42d is provided on the fourth side surface 16b (see FIG. 6) side opposite to the third side surface 16a (see FIG. 1), and guides the chain 2. The second guide surface 42d is formed in a concave shape so that the thickness gradually decreases toward the side of the second speed change gear 42c.

  Here, the third side surface 16a of the second sprocket 16 is a front surface disposed on the outside in the axial direction far from the bicycle frame when the crank assembly 10 is mounted on the bicycle. The fourth side surface 16b is a back surface arranged on the inner side in the axial direction close to the bicycle frame.

  Here, an example in which the second shift region 44 does not include the protrusions and the recesses of the first shift region 34 is shown, but the second shift region 44 includes at least one of the protrusions and the recesses. Also good.

<Speed change operation in crank assembly>
In the crank assembly 10 having such a configuration, when an upshift operation is performed from the second sprocket 16 to the first sprocket 14 by a front derailleur (not shown), the crank assembly 10 rotates in the traveling rotation direction R. In this state, when the front derailleur moves from a position facing the second sprocket 16 to a position facing the first sprocket 14, the chain 2 is separated from the teeth of the second sprocket 16. Then, the chain 2 is supported by the second protrusion 36b and moves outward in the radial direction. Then, the chain 2 is supported by the first protrusion 36 a via the step portion 38 of the first speed change region 34, and is guided and engaged with the teeth 32 of the first sprocket 14.

  On the other hand, when the downshift operation is performed from the first sprocket 14 to the second sprocket 16 by the front derailleur, the crank assembly 10 is rotated in the traveling rotation direction R. In this state, when the front derailleur moves from a position facing the first sprocket 14 to a position facing the second sprocket 16, the chain 2 is separated from the teeth of the first sprocket 14. Then, the chain 2 is guided toward the teeth 42 of the second sprocket 16 and engaged with the teeth 42.

Second Embodiment
As shown in FIG. 1, a bicycle crank assembly 110 according to the second embodiment includes a crank arm 12, a first sprocket 114 (an example of a bicycle sprocket), and a second sprocket 116 (an example of a bicycle sprocket). . The first sprocket 114 and the second sprocket 116 are an example of a bicycle sprocket assembly.

  The configuration of the second embodiment is substantially the same as the configuration of the first embodiment except for the configurations of the first sprocket 114 and the second sprocket 116. For this reason, only the structure of the 1st sprocket 114 and the 2nd sprocket 116 is demonstrated here, and description of the structure substantially the same as the structure of 1st Embodiment is abbreviate | omitted. In addition, about the structure abbreviate | omitted here, it applies to description of the structure of 1st Embodiment. Moreover, the same code | symbol is attached | subjected about the structure similar to 1st Embodiment.

  The first sprocket 114 includes a first sprocket body 30 (an example of a main body part), a first annular part 31 (an example of an annular part), and a plurality of teeth 132 (an example of a first tooth part and a second tooth part). , A first shift region 34 (an example of a shift region).

  Here, the configuration of the first sprocket body 30, the configuration of the first annular portion 31, and the configuration of the first shift region 34 are substantially the same as the configuration of the first embodiment, and thus description thereof is omitted here. . Moreover, about the structure of the some tooth | gear 132, only the structure different from the structure of 1st Embodiment is demonstrated below.

  As shown in FIG. 7, each of the plurality of first teeth 132a (an example of the first teeth) included in the plurality of teeth 132 includes a first main body portion 132b, a first recess 32e, and a first additional portion 132c. Have. Since the first recess 32e has the same configuration as that of the first embodiment, the description thereof is omitted here.

  The first main body portion 132 b is provided in the first annular portion 31. Specifically, the first main body portion 132 b is formed integrally with the first annular portion 31 so as to protrude outward in the radial direction from the first annular portion 31. The first main body 132b has a surface 20a on the first side surface 14a side and a back surface 20b on the second side surface 14b side. The back surface 22a is a surface opposite to the front surface 20a in the axial direction of the rotation center axis X.

  The first additional portion 132c is attached to the first main body portion 132b in order to increase the width of the first main body portion 132b. Specifically, the first additional portion 132c is attached to each of the front surface 20a and the back surface 22a of the first main body portion 132b. As described above, by attaching the first additional portion 132c to the front surface 20a and the back surface 22a of the first main body portion 132b, the first maximum axial width W1 is set to a predetermined width. The first additional portion 132c is made of metal, for example, aluminum, titanium, or iron / stainless steel. The first additional portion 132c is attached to the first teeth 132a by adhesion, diffusion bonding, caulking, or casting.

  Here, an example is shown in which the first additional portion 132c is attached to each of the front surface 20a and the back surface 22a of the first main body portion 132b. Instead of this, the first maximum axial width W1 may be set by attaching the first additional portion 132c only to the front surface 20a or only the back surface 22a of the first main body portion 132b.

  The second sprocket 116 includes a second sprocket body 40 (an example of a main body part), a second annular part 41 (an example of an annular part), and a plurality of teeth 142 (an example of a first tooth part and a second tooth part). , A second shift region 44 (an example of a shift region).

  Here, the configuration of the second sprocket main body 40, the configuration of the second annular portion 41, and the configuration of the second shift region 44 are substantially the same as the configuration of the first embodiment, and thus the description thereof is omitted here. . Moreover, about the structure of the some tooth | gear 142, only the structure different from the structure of 1st Embodiment is demonstrated below.

  Each of the plurality of third teeth 142a (an example of the first teeth) included in the plurality of teeth 142 includes a second main body portion 142b and a second addition portion 142c. The configurations of the second main body 142b and the second additional portion 142c are substantially the same as the configurations of the first main body 132b and the first additional portion 132c described above. That is, the third maximum axial width W3 is set to a predetermined width by attaching the second additional portion 142c to the front surface 20a and the back surface 20b of the second main body portion 142b.

<Other embodiments>
As mentioned above, although one Embodiment of this invention was described, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the summary of invention. In particular, a plurality of embodiments and modifications described in this specification can be arbitrarily combined as necessary.

  (A) In the first and second embodiments, the two front sprockets 14 and 16 (114 and 116) are exemplified as the bicycle sprocket assembly, but the present invention is not limited to this. The present invention is also applicable to a bicycle sprocket assembly including only one front sprocket that does not have a speed change region.

  (B) In the first and second embodiments, an example in which the second sprocket body 40 and the plurality of teeth 42 and 142 are integrally formed has been shown, but the present invention is not limited to this. The second sprocket body 40 and the plurality of teeth 42 and 142 may be separate bodies. For example, the plurality of teeth 42 and 142 may be made of metal, and the second sprocket body 40 may be made of nonmetal. In this case, the weight can be reduced by using aluminum, titanium, or iron / stainless steel as the metal and using a synthetic resin such as carbon fiber reinforced resin as the nonmetal.

  (C) In the first and second embodiments, the portions where the first teeth 32a, 132a and the second teeth 32b engage with the chain roller 2c, and the third teeth 42a, 142a and the fourth teeth 42b are chain rollers. The portion engaged with 2c may be configured as shown in FIG.

  This configuration is substantially the same in the first sprockets 14 and 114 and the second sprockets 16 and 116. For this reason, this structure is demonstrated here using the 1st tooth | gear 232a and the 2nd tooth | gear 232b of the 1st sprocket 14,114.

  The chain roller 2c can be engaged between the first teeth 232a and the second teeth 232b (see FIGS. 1 and 5). As shown in FIG. 8, each of the first tooth 232 a and the second tooth 232 b has a drive surface 233 and a non-drive surface 234.

  Since this configuration is substantially the same for the first tooth 232a and the second tooth 232b, the first tooth 232a will be described here.

  Each of the first teeth 232a and the second teeth 232b has a surface 20a on the first side surface 14a side, a back surface (not shown) on the second side surface 14b side, a driving surface 233, and a non-driving surface 234. The back surface 22 is a surface opposite to the front surface 20a in the axial direction of the rotation center axis X (direction perpendicular to the paper surface of FIG. 8).

  The drive surface 233 is a surface that connects the front surface 20a and the back surface in the axial direction on the downstream side in the traveling rotation direction R. The drive surface 233 includes a contact point CP and a first extension portion 233a (an example of a drive surface extension portion). The contact point CP is a portion where the chain roller 2c comes into contact. Specifically, the contact point CP is a point where the chain roller 2c contacts the driving surface 233 during driving.

  The first extension portion 233a is formed integrally with the drive surface 233. The first extending portion 233a extends in the circumferential direction on the radially outer side from the contact point CP. Specifically, the first extending portion 233a protrudes downstream in the traveling rotation direction R on the radially outer side from the contact point CP.

  The non-driving surface 234 is a surface that connects the front surface 20a and the rear surface in the axial direction on the upstream side in the traveling rotation direction R. For example, the non-driving surface 234 is formed symmetrically with the driving surface 233 with respect to a straight line CL that connects the rotation center axis X and the center position in the circumferential direction of the first tooth 232a (second tooth 232b). . The non-drive surface 234 may be formed asymmetrically with the drive surface 233 with respect to a straight line CL connecting the rotation center axis X and the center position in the circumferential direction of the first tooth 232a (second tooth 232b).

  The non-driving surface 234 includes a second extending portion 234a (an example of a non-driving surface extending portion). The movement of the chain roller 2c to the outside in the radial direction is suppressed by the second extending portion 234a. The second extending portion 234a is formed integrally with the non-driving surface 234. Here, as described above, since the non-driving surface 234 is formed in line symmetry with the driving surface 233, the second extending portion 234a extends in the circumferential direction on the opposite side to the first extending portion 233a. Put out. That is, the second extending portion 234a extends in the circumferential direction, for example, upstream in the traveling rotation direction R.

  Thereby, the driving force of the first sprocket 14 can be reliably transmitted to the chain roller 2c, that is, the chain 2 by the driving surface 233. Further, the drive surface 233 and the non-drive surface 234 can reliably suppress the movement of the chain roller 2c to the outside in the radial direction.

  Here, an example in which each of the first tooth 232a and the second tooth 232b has a driving surface 233 and a non-driving surface 234 is shown. Instead, only the first tooth 232a or only the second tooth 232b may be configured to have the drive surface 233 and the non-drive surface 234. Further, the first tooth 232a and / or the second tooth 232b may be configured to have only the driving surface 233 or only the non-driving surface 234.

  (D) In the first and second embodiments, an example in which the front sprockets 14 and 15 are mounted on the crankshaft 19 through the crank arm 12 so as not to move is shown. Alternatively, the front sprockets 14 and 15 may move along the crankshaft 19 (rotation center axis X). Alternatively, only one front sprocket 14 may be used and the front sprocket 14 may be moved along the crankshaft 19 (rotation center axis X).

  (E) The front sprockets 14 and 15 shown in the first and second embodiments may form an outline by a 3D printer, and then the second teeth 32b and the fourth teeth 42b may be formed by press working such as forging. Good.

  (F) In the first and second embodiments, the example in which the first teeth 32a and 132a and the third teeth 42a and 142a are formed in a substantially + shape is shown. It is not limited. For example, at least a part of the first teeth 32a and the third teeth 42a may have other shapes such as rhombus, trapezoid, triangle, hexagon, and octagon.

  As shown in FIG. 10, the first teeth 332a and / or the third teeth 342a are preferably octagonal when viewed from the radial direction of the bicycle sprocket. In this case, a tooth shape that can avoid excessive interference between the first teeth 332a and / or the third teeth 342a and the inner link plate 2b and that securely holds the outer link plate 2a is formed by pressing, for example, forging. easy.

  Here, the octagonal shape is not limited to a regular octagonal shape, and may be any shape as long as the shape has eight sides. Further, the eight sides constituting the octagon are not limited to a straight line but may be a curve having a gentle curvature.

  Specifically, as shown in FIGS. 9 and 10, when the first teeth 332a and the third teeth 342a have the above octagonal shape, the first teeth 332a and the third teeth 342a have the first surface 352a, It has a second surface 352b, a third surface 352c, and an inclined portion 353.

  The first surface 352a is a surface on the first side surface 14a side of the first sprocket 14 in the first tooth 332a, and a surface on the third side surface 16a side of the second sprocket 16 in the third tooth 342a.

  The second surface 352b is a surface on the second side surface 14b side of the first sprocket 14 in the first tooth 332a, and a surface on the fourth side surface 16b side of the second sprocket 16 in the third tooth 342a.

  The third surface 352c extends in the circumferential direction between the axial directions of the first surface 352a and the second surface 352b. The third surface 352c includes a drive surface 352d, a non-drive surface 352e, and a tip surface 352f that connects the drive surface 352d and the non-drive surface 352e in the circumferential direction. The inclined portion 353 is for avoiding excessive interference with the inner link plate 2b. The inclined portion 353 includes a first chamfered surface 353a, a second chamfered surface 353b, a third chamfered surface 353c, and a fourth chamfered surface 353d.

  The first chamfered surface 353a is formed from the first surface 352a to the third surface 352c on the driving side. The second chamfered portion 353b is formed from the second surface 352b to the third surface 352c on the driving side. The third chamfered surface 353c is formed from the first surface 352a to the third surface 352c on the non-driving side. The fourth chamfered surface 353d is formed from the second surface 352b to the third surface 352c on the non-driving side.

  In other words, the first chamfered surface 353a is formed at a corner portion constituted by the first surface 352a and the third surface 352c on the driving side. The second chamfered surface 353b is formed at a corner portion constituted by the second surface 352b and the third surface 352c on the driving side. The third chamfered surface 353c is formed at a corner portion constituted by the first surface 352a and the non-driving side third surface 352c. The fourth chamfered surface 353d is formed in a corner portion constituted by the second surface 352b and the non-driving side third surface 352c.

  Here, since the driving side of the first teeth 332a and the third teeth 342a tends to interfere with the inner link plate 2b more excessively than the non-driving side, the first chamfered surface 353a formed on the driving side. The second chamfered surface 353b preferably has a larger area than the third chamfered surface 353c and the fourth chamfered surface 353d formed on the non-driving side.

  By the first to fourth chamfered surfaces 353a, 353b, 353c, and 353d, excessive interference between the first teeth 332a and the third teeth 342a and the inner link plate 2b can be avoided. Further, the first to fourth chamfered surfaces 353a, 353b, 353c, and 353d have different shapes from the concave portions of the first and second embodiments, and are inclined surfaces constituted by straight lines or gentle curves. It is easy to form by processing such as forging.

  When the first teeth 332a and the third teeth 342a have an octagonal shape, the first axial contact width L3 at which the drive surfaces of the first teeth 332a and the third teeth 342a contact the chain roller 2c is the second tooth It is preferable that the driving surfaces of 332b and the fourth teeth 342b have substantially the same length as the second axial contact width L4 that contacts the chain roller 2c.

  (G) In the first and second embodiments, an example in which the first teeth 32a and 132a are formed in a substantially T shape has been described, but the present invention is not limited to this. For example, a part of the first teeth 32a may be other shapes such as a diamond shape, a trapezoidal shape, a triangular shape, a hexagonal shape, and an octagonal shape.

  (H) In the first and second embodiments, the first speed change region 34 has the second protrusion 36b, but the second protrusion 36b may not be provided.

  (I) In the first and second embodiments, the number of the plurality of sprocket mounting arms 24 is four, but the number of sprocket mounting arms is not limited to four.

  (J) In the first and second embodiments, the first transmission region 34 and the second transmission region 44 of each of the first sprocket 14 and the second sprocket 16 include the second teeth 32b having the − (minus) shape and the second gear 32b. Four teeth 42b may be included.

  (K) In the said 2nd Embodiment, although the example in case the additional part of the 1st tooth | gear 32a was metal was shown, the additional part may be non-metallic. For example, when the additional portion is made of non-metal, the additional portion is attached to the first tooth by bonding or integral molding. In this case, noise caused by contact between the chain and the sprocket teeth during pedaling can be reduced.

  (L) At least one of the first teeth 32a and 132a and the second teeth 32b and 132b of the bicycle sprocket in the present invention may preferably have a plating layer.

  For example, when the first teeth 32a and 132a and the second teeth 32b and 132b are made of aluminum, the plating layer is preferably a nickel plating layer for the purpose of wear resistance. When the first teeth 32a and 132a and the second teeth 32b and 132b are made of iron, the plating layer is preferably a nickel chrome plating layer for the purpose of rust prevention.

  When the first teeth 32a, 132a and the second teeth 32b, 132b are made of iron, the first teeth 32a, 132a and the second teeth 32b, 132b are electrodeposited coating layers for the purpose of rust prevention and coloring. It is also preferable to have

  (M) In the first and second embodiments, the first sprocket 14 includes the first sprocket body 30 made of synthetic resin, the first annular portion 31 made of metal, and the first tooth portion 32b. An example of the case is shown.

  Instead, the first sprocket 14 may be made of metal, and the first sprocket body 30, the first annular portion 31, and the first tooth portion 32b may be integrally molded. In this case, the first sprocket body 30, the first annular portion 31, and the first tooth portion 32b are made of metal such as aluminum, titanium, or iron / stainless steel.

  An example of the first sprocket 314 configured in this manner is shown in FIG. FIG. 11 has substantially the same configuration as that of the first and second embodiments, and the same reference numerals as those of the first embodiment are given to representative configurations.

  (N) Instead of the first sprockets 14 and 114 of the first and second embodiments, the first sprocket 214 may be configured as shown in FIGS. 12A and 12B. In FIGS. 12A and 12B, substantially the same configurations as those of the first and second embodiments are expressed using the reference numerals of the first embodiment.

  In the first sprocket 214, the first through hole 130 a is provided in the first sprocket body 30. A second through hole 130 b is provided in the first annular portion 31. A ring member 130c, for example, a washer is disposed in the first through hole 130a. Specifically, the first sprocket body 30 includes the first annular portion 31 and the ring member 130c so that the inner peripheral surface of the ring member 130c is substantially flush with the inner peripheral surface of the second through hole 130b. And is integrally molded.

  When the first sprocket 214 is configured in this way, the first fixing bolts 26 are inserted into the ring members 130c, the second through holes 130b, and the first mounting portions 24a, and nut members (not shown). ). As a result, the first sprocket body 30 is fixed to the sprocket mounting arm 24.

  (O) In the first and second embodiments, an example in which the second teeth 32b of the first sprocket 14 are formed together with the first recesses 32e by press work, for example, forging, has been shown. Instead, as shown in FIGS. 13A to 13D, the second teeth 32b may be formed by press working (for example, forging) and a cutting process. Note that FIGS. 13A to 13D schematically represent each process for ease of explanation.

  In this case, the second teeth 32b include a first pressing step (see FIG. 13B), a cutting step after the first pressing step (see FIG. 13C), and a second pressing step after the cutting step (FIG. 13D). For example).

  As shown in FIG. 13D, the second tooth 32b has a fifth surface 52a (an example of the first surface) and a sixth surface 52b (an example of the first surface). For example, the fifth surface 52a is formed on the first side surface 14a (see FIG. 2) side of the first sprocket 14 in the second tooth 32a. The sixth surface 52b is a surface located on the opposite side to the fifth surface 52a in the axial direction parallel to the rotation center axis X. For example, the sixth surface 52b is formed on the second side surface 14b (see FIG. 4) side of the first sprocket 14 in the second tooth 32b.

  Specifically, as shown in FIG. 13A, in an initial state, a surface (a first pressing portion 152a described later) on which a fifth surface 52a of the second tooth portion 32b is configured and a surface on which a sixth surface 52b is configured. (Second pressing portion 152c described later) is formed on substantially the same surface as the outer surface of the first annular portion 31 of the first sprocket 14.

  The first pressing step is a step of pressing the fifth surface 52a side of the second tooth 32b. As shown in FIG. 13B, in the first pressing step, the fifth surface 52a side of the second tooth 32b is pressed by the pressing member A of the pressing device (not shown) with the first annular portion 31 fixed. .

  Here, the 1st press part 152a which the press member A presses is a part in which the 2nd tooth | gear 32b and the 1st recessed part 32e are formed. As described above, when the pressing member A presses the first pressing portion 152a, the fifth surface 52a of the second tooth portion 32b is formed, and the sixth surface 52b side is substantially opposite to the first pressing portion 152a. The located part protrudes. Hereinafter, this portion is referred to as a protruding portion 152b.

  The cutting step is a step of cutting the protruding portion 152b protruding in the axial direction by the first pressing step on the sixth surface 52b side of the second tooth 32b. As shown in FIG. 13C, in the cutting process, the protruding portion 152 b formed on the sixth surface 52 b side is cut by the cutting device B. Specifically, the cutting device B cuts the surface after the projecting portion 152b is cut so as to be substantially flush with the outer surface of the first annular portion 31.

  The second pressing step is a step of pressing the sixth surface 52b side of the second tooth 32b. As shown in FIG. 13D, in the second pressing step, the sixth surface of the second tooth 32b is in a state where the mold D for forming the outer shape of the second tooth 32b is in contact with the first pressing portion 152a. The 52b side is pressed by the pressing member C of the pressing device.

  Here, the 2nd press part 152c which the press member C presses is a part in which the 2nd tooth | gear 32b and the 1st recessed part 32e are formed. As described above, when the pressing member C presses the second pressing portion 152c, the sixth surface 52b of the second tooth portion 32b is formed. Further, a tooth tip 52c of the second tooth portion 32b including the fifth surface 52a and the sixth surface 52b is formed.

  As described above, the second teeth 32b can be formed by using the first pressing step, the cutting step, and the second pressing step. In addition, after the 2nd tooth | gear 32b is formed as mentioned above, the grinding | polishing process for adjusting the shape of the 2nd tooth | gear 32b, and the plating process (preferably nickel plating process) which raises the abrasion resistance of the 2nd tooth | gear 32b are performed. , May be added selectively.

  Here, an example in which the second teeth 32b are formed by pressing and cutting processes is shown, but the fourth teeth 42b of the second sprocket 16 may be formed in the same manner.

  (P) In the first and second embodiments and the other embodiments, the front sprockets 14 and 16 are exemplified as bicycle sprockets, but the present invention is not limited to this. The present invention is also applicable to a rear sprocket.

  Widely applicable to bicycle sprockets and bicycle sprocket assemblies.

2 Chain 2a Outer link plate 2b Inner link plate 2c Chain roller 10, 110 Bicycle crank assembly 14, 114 First sprocket 16, 116 Second sprocket 32a, 132a First tooth 32b, 132b Second tooth 34 First shift region 32e 1st recessed part 42a, 142a 3rd tooth | gear 42b 4th tooth | gear 42e 2nd recessed part 132b 1st main-body part 132c 1st additional part 142b 2nd main-body part 142c 2nd additional part CP Contact point L1 1st axial direction distance L2 2nd Axial spacing W1 First maximum axial width W2 Second maximum axial width W3 Third maximum axial width W4 Fourth maximum axial width

  The present invention relates to a bicycle sprocket and a bicycle sprocket assembly.

  A conventional bicycle sprocket is provided on each of the crank assembly and the rear wheel. A chain is meshed between the sprocket of the crank assembly and the sprocket of the rear wheel. Thereby, the rotation of the crank assembly is transmitted to the rear wheel via the chain.

  In the chain, inner link plates and outer link plates are alternately connected. The distance between the pair of inner link plates facing each other is smaller than the distance between the pair of outer link plates facing each other. For this reason, when the sprocket teeth are formed so that the thicknesses (engagement widths) of the sprocket teeth are all the same, the gap between the outer link plate and the sprocket teeth in the direction of the sprocket thickness is the inner link plate. And larger than the gap between the sprocket teeth.

  In such a conventional structure, the engagement between the chain and the sprocket tends to be loosened by the gap between the outer link plate and the sprocket teeth in the thickness direction of the sprocket. Therefore, a sprocket has been proposed in which the thickness of the teeth meshing with the outer link plate is larger than the thickness of the teeth meshing with the inner link plate (see Patent Document 1).

US2013 / 0139642

  In the conventional sprocket, by cutting the teeth that mesh with the inner link plate, the thickness of the teeth that mesh with the outer link plate is made larger than the thickness of the teeth that mesh with the inner link plate (see, for example, US2013 / 0139642) (See paragraph 0045).

  In this case, since the sprocket is formed, there is a problem that the processing time becomes long at the time of cutting. That is, when producing the sprocket, it has been difficult to improve the sprocket productivity.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a bicycle sprocket having high chain holding power and excellent productivity. Another object of the present invention is to provide a bicycle sprocket assembly having high chain holding power and excellent productivity.

  (1) A bicycle sprocket according to one aspect of the present invention has a rotation center axis. The bicycle sprocket includes first teeth and second teeth. The first tooth has a first axial chain engagement width. The first axial chain engagement width is smaller than the first axial interval in the outer link of the bicycle chain. Further, the first axial chain engagement width is larger than the second axial interval in the inner link connected to the outer link. The second tooth has a second axial chain engagement width. The second axial chain engagement width is smaller than the second axial spacing. The second tooth is formed by deformation of the material.

  In this sprocket, the first axial chain engagement width of the first teeth is smaller than the first axial interval in the outer link and larger than the second axial interval in the inner link. Further, the second axial chain engagement width of the second teeth is smaller than the second axial interval. Thereby, a chain can be reliably hold | maintained with a sprocket. Further, since the second teeth are formed by deformation of the material, the productivity of the sprocket can be improved as compared with the conventional technique.

  (2) A bicycle sprocket according to another aspect of the present invention may be configured as follows. The second tooth is formed by press working.

  In this case, since the second teeth are formed by press working, the productivity of the sprocket can be reliably improved.

  (3) A bicycle sprocket according to another aspect of the present invention may be configured as follows. The first tooth has a recess. The recess is for avoiding excessive interference with the inner link, and is formed by pressing.

  In this case, even if the first teeth are disposed between the outer links, excessive interference with the inner links can be avoided by the recesses. Moreover, since the recess is formed by press working, the productivity of the recess can be improved.

  (4) A bicycle sprocket according to another aspect of the present invention may be configured as follows. The first tooth has a recess. The recess is for avoiding excessive interference with the inner link, and is formed by cutting.

  In this case, even if the first teeth are disposed between the outer links, excessive interference with the inner links can be avoided by the recesses. Moreover, since a recessed part is formed by cutting, a recessed part can be formed correctly.

  (5) A bicycle sprocket according to another aspect of the present invention may be configured as follows. The first tooth has a main body portion and an additional portion. The additional portion is attached to the main body portion in order to increase the width of the main body portion. The first axial chain engagement width is a width obtained by attaching the additional portion to the main body portion.

  In this case, since the first tooth has the first axial chain engagement width larger than the second axial interval by attaching the additional portion to the main body portion, the material of the additional portion can be freely selected.

  (6) A bicycle sprocket according to another aspect of the present invention may be configured as follows. The additional portion of the first tooth is made of metal. This additional portion is attached to the first tooth by bonding, diffusion bonding, caulking, or casting.

  In this case, since the additional portion of the first tooth is made of metal, the strength and rigidity of the additional portion can be sufficiently secured. Moreover, this additional part can be reliably attached to the first tooth by adhesion, diffusion bonding, caulking, or casting.

  (7) A bicycle sprocket according to another aspect of the present invention may be configured as follows. The additional portion of the first tooth is made of nonmetal. This additional portion is attached to the first tooth by bonding or integral molding.

  In this case, since the additional portion of the first tooth is made of a non-metal, it is possible to facilitate molding and reduce the weight of the additional portion. Moreover, this additional part can be reliably attached to a 1st tooth | gear by adhesion | attachment or integral molding.

  (8) A bicycle sprocket according to another aspect of the present invention may be configured as follows. Each of the first tooth and the second tooth has a drive surface. The drive surface includes a contact point with which the chain roller contacts. A drive surface extension is formed on the drive surface. The drive surface extending portion extends in the circumferential direction on the radially outer side from the contact point.

In this case, in each of the first tooth and the second tooth, the driving surface extending portion of the driving surface extends in the circumferential direction on the radially outer side from the contact point of the driving surface. Therefore, the radially outward movement of the sprocket chain, Ru can be reliably suppressed.

  (9) A bicycle sprocket according to another aspect of the present invention may be configured as follows. Each of the first tooth and the second tooth has a non-driving surface. A non-driving surface extending portion is formed on the non-driving surface. The non-driving surface extending portion extends in the circumferential direction in order to suppress the movement of the chain roller to the radially outer side.

  In this case, the movement of the chain to the outside in the radial direction can be reliably suppressed by the non-driving surface extending portions of the non-driving surfaces of the first teeth and the second teeth.

  (10) A bicycle sprocket according to another aspect of the present invention may be configured as follows. Each of the first tooth and the second tooth has a drive surface and a non-drive surface. The drive surface includes a contact point with which the chain roller contacts. A drive surface extension is formed on the drive surface. The drive surface extending portion extends in the circumferential direction on the radially outer side from the contact point. Further, a non-driving surface extending portion is formed on the non-driving surface. The non-driving surface extending portion extends in the circumferential direction in order to suppress the movement of the chain roller to the radially outer side.

  In this case, in each of the first tooth and the second tooth, the driving surface extending portion of the driving surface extends in the circumferential direction on the radially outer side from the contact point of the driving surface. For this reason, the movement of the chain roller to the outer side in the radial direction can be reliably suppressed by the non-driving surface extending portions of the non-driving surfaces of the first teeth and the second teeth.

  (11) A bicycle sprocket according to another aspect of the present invention may be configured as follows. The bicycle sprocket further includes a shift region for shifting the chain at the time of shifting.

  In this case, a shiftable bicycle sprocket excellent in chain holding force can be provided.

  (12) A bicycle sprocket according to another aspect of the present invention may be configured as follows. The bicycle sprocket further includes a metallic annular portion and a non-metallic main body portion. In the metal annular portion, the first teeth and the second teeth are provided on the outer periphery. The non-metallic body portion is attached to the radially inner periphery of the metallic annular portion.

  In this case, since the sprocket body is made of non-metal, the sprocket can be reduced in weight. Moreover, since the annular part and the first and second teeth of the sprocket are made of metal, the strength and rigidity of the part where the sprocket engages with the chain can be improved.

  (13) A bicycle sprocket according to another aspect of the present invention may be configured as follows. In the bicycle sprocket, the pressing process is forging.

  In this case, since the press work is forging, the productivity of the sprocket can be reliably and easily improved.

  (14) A bicycle sprocket according to another aspect of the present invention may be configured as follows. The second tooth is formed by pressing and cutting processes. Even if the second teeth are formed in this way, the productivity of the sprocket can be improved.

  (15) A bicycle sprocket according to another aspect of the present invention may be configured as follows. The second teeth are formed by a first pressing step, a cutting step after the first pressing step, and a second pressing step after the cutting step. Thus, even if the second teeth are formed stepwise, the productivity of the sprocket can be improved.

  (16) A bicycle sprocket according to another aspect of the present invention may be configured as follows. The second tooth has a first surface and a second surface located on the opposite side of the first surface in the axial direction parallel to the rotation center axis. The first pressing step is a step of pressing the first surface side of the second tooth. The second pressing step is a step of pressing the second surface side of the second tooth. By forming the second teeth in this way, both surfaces (first surface and second surface) of the second teeth can be easily formed. That is, the productivity of the sprocket can be improved.

  (17) A bicycle sprocket according to another aspect of the present invention may be configured as follows. The cutting step is a step of cutting the protruding portion protruding in the axial direction by the first pressing step on the second surface side of the second tooth. By forming the second teeth in this way, the second surface of the second teeth can be easily formed into a shape in the second pressing step. That is, the productivity of the sprocket can be improved.

  (18) A bicycle sprocket according to one aspect of the present invention has a rotation center axis. The bicycle sprocket includes first teeth and second teeth. The first tooth has a first axial chain engagement width. The first axial chain engagement width is smaller than the first axial interval in the outer link of the bicycle chain. Further, the first axial chain engagement width is larger than the second axial interval in the inner link connected to the outer link. The second tooth has a second axial chain engagement width. The second axial chain engagement width is smaller than the second axial spacing. The first tooth has a substantially octagonal shape when viewed from the outside in the radial direction.

  In this sprocket, the first axial chain engagement width of the first teeth is smaller than the first axial interval in the outer link and larger than the second axial interval in the inner link. Further, the second axial chain engagement width of the second teeth is smaller than the second axial interval. Thereby, a chain can be reliably hold | maintained with a sprocket.

  Further, since the first tooth has a substantially octagonal shape when viewed from the outside in the radial direction, excessive interference between the first tooth and the inner link plate can be avoided, and the outer link plate can be The tooth shape to be reliably held can be easily formed by press work, for example, forging.

  (19) A bicycle sprocket according to one aspect of the present invention has a rotation center axis. The bicycle sprocket includes first teeth and second teeth. The first tooth has a first axial chain engagement width. The first axial chain engagement width is smaller than the first axial interval in the outer link of the bicycle chain. Further, the first axial chain engagement width is larger than the second axial interval in the inner link connected to the outer link. The second tooth has a second axial chain engagement width. The second axial chain engagement width is smaller than the second axial spacing. The first tooth has an inclined portion for avoiding excessive interference with the inner link.

  In this sprocket, the first axial chain engagement width of the first teeth is smaller than the first axial interval in the outer link and larger than the second axial interval in the inner link. Further, the second axial chain engagement width of the second teeth is smaller than the second axial interval. Thereby, a chain can be reliably hold | maintained with a sprocket.

  In addition, since the first tooth has an inclined portion, even if the first tooth is disposed between the outer links, the inclined portion can avoid excessive interference with the inner link, and the outer link. A tooth shape that reliably holds the plate can be easily formed by press work, for example, forging.

  (20) A bicycle sprocket according to another aspect of the present invention may be configured as follows. The first tooth further includes a first surface, a second surface, and a third surface. The third surface extends in the circumferential direction between the axial direction of the first surface and the second surface. The inclined portion has a first chamfered surface, a second chamfered surface, a third chamfered surface, and a fourth chamfered surface.

The first chamfered surface is formed from the first surface to the third surface on the driving side. The second chamfered surface is formed from the second surface to the third surface on the driving side. The third chamfered surface is formed from the first surface to the third surface on the non-driving side. The fourth chamfered surface is formed from the second surface to the third surface on the non-driving side.

  In this case, excessive interference between the first teeth and the inner link plate can be avoided by the first to fourth chamfered surfaces, and the tooth shape for securely holding the outer link plate can be obtained by pressing, for example, forging. It can be formed easily.

  (21) A bicycle sprocket according to another aspect of the present invention may be configured as follows. The first axial contact width at which the drive surface of the first tooth contacts the chain roller is formed to be substantially the same length as the second axial contact width at which the drive surface of the second tooth contacts the chain roller.

  In this case, since the first axial contact width and the second axial contact width are substantially the same length, the driving force can be stably transmitted from the sprocket to the chain.

(22) A bicycle sprocket according to one aspect of the present invention has a rotation center axis. The bicycle sprocket includes first teeth and second teeth. The first tooth has a first axial chain engagement width. The first axial chain engagement width is smaller than the first axial interval in the outer link of the bicycle chain. Further, the first axial chain engagement width is larger than the second axial interval in the inner link connected to the outer link. The second tooth has a second axial chain engagement width. The second axial chain engagement width is smaller than the second axial spacing. At least one of the first tooth and the second tooth has a plating layer.

  In this sprocket, the first axial chain engagement width of the first teeth is smaller than the first axial interval in the outer link and larger than the second axial interval in the inner link. Further, the second axial chain engagement width of the second teeth is smaller than the second axial interval. Thereby, a chain can be reliably hold | maintained with a sprocket.

  In addition, since at least one of the first tooth and the second tooth has a plating layer, it is possible to improve the wear resistance and rust prevention of at least one of the first tooth and the second tooth.

  (23) A bicycle sprocket according to another aspect of the present invention may be configured as follows. The first and second teeth are made of aluminum. The plating layer is a nickel plating layer. In this case, the wear resistance of the first tooth and the second tooth can be improved.

  (24) A bicycle sprocket according to another aspect of the present invention may be configured as follows. The first tooth and the second tooth are made of iron. The plating layer is a nickel chrome plating layer. In this case, the antirust property of the first tooth and the second tooth can be improved.

  (25) A bicycle sprocket assembly according to another aspect of the present invention includes the sprocket according to any one of (1) to (24).

  This sprocket assembly can obtain the same effects as the effects described in (1) to (24) above.

  (26) A bicycle sprocket assembly according to another aspect of the present invention may be configured as follows. In this sprocket assembly, the sprocket is a single front sprocket.

  Even if the sprocket assembly is configured in this manner, the same effects as described in the above (1) to (24) can be obtained.

  (27) A bicycle sprocket assembly according to another aspect of the present invention may be configured as follows. In this sprocket assembly, the sprocket is a plurality of front sprockets.

  Even if the sprocket assembly is configured in this manner, the same effects as described in the above (1) to (24) can be obtained.

  (28) A bicycle sprocket assembly according to another aspect of the present invention may be configured as follows. In the present sprocket assembly, the sprocket is movable along the rotation center axis.

  Even if the sprocket assembly is configured in this manner, the same effects as described in the above (1) to (24) can be obtained.

  (29) A bicycle sprocket assembly according to another aspect of the present invention may be configured as follows. In this sprocket assembly, the sprocket is a rear sprocket.

  Even if the sprocket assembly is configured in this manner, the same effects as described in the above (1) to (24) can be obtained.

  According to the present invention, it is possible to provide a bicycle sprocket having a high chain holding force and excellent productivity. In addition, a bicycle sprocket assembly having a high chain holding force and excellent productivity can be provided.

The front view of the crank assembly for bicycles by the 1st and 2nd embodiment of the present invention. The front perspective view of the 1st sprocket by a 1st embodiment. The rear view of the 1st sprocket by a 1st embodiment. The rear perspective fragmentary view of the 1st and 2nd sprocket by 1st Embodiment. The side surface partial view which looked at the 1st sprocket and 2nd sprocket by 1st Embodiment from the radial direction outer side. The front perspective view of the 2nd sprocket by 1st Embodiment. Sectional drawing of the 3rd tooth of the 1st tooth of the 1st sprocket and the 2nd sprocket by a 2nd embodiment of the present invention. The front view of the 1st tooth of the 1st sprocket and the 3rd tooth of the 2nd sprocket by other embodiments of the present invention. The partial front view of the tooth | gear part of the 1st and 2nd sprocket by other embodiment of this invention. The side surface partial view which looked at the tooth | gear part of the 1st and 2nd sprocket by other embodiment of this invention from the radial direction outer side. The front view of the 1st sprocket by other embodiments of the present invention. The front view of the 1st sprocket by other embodiments of the present invention. The fragmentary sectional view of the 1st sprocket by other embodiments of the present invention. The schematic diagram for demonstrating the formation form of the 2nd tooth and 4th tooth | gear by other embodiment of this invention.

<First Embodiment>
As shown in FIG. 1, a bicycle crank assembly 10 (hereinafter referred to as a crank assembly) according to a first embodiment includes a crank arm 12, a first sprocket 14 (an example of a bicycle sprocket), and a second sprocket. 16 (an example of a bicycle sprocket). The first sprocket 14 and the second sprocket 16 are an example of a bicycle sprocket assembly.

  In the crank assembly 10, the first sprocket 14 and the second sprocket 16 are front sprockets that can be engaged with the chain 2. The second sprocket 16 has fewer teeth than the first sprocket 14. The chain 2 includes a pair of outer link plates 2a, a pair of inner link plates 2b, and a pair of outer link plates 2a and a chain roller 2c that couples the pair of inner link plates 2b.

<Crank arm>
The crank arm 12 is connected to the crankshaft 19 so as to be integrally rotatable. The crank arm 12 includes a sprocket mounting portion 20 and an arm portion 22 provided integrally with or separate from the sprocket mounting portion 20.

  The sprocket mounting portion 20 has a plurality (for example, four) of sprocket mounting arms 24. The plurality of sprocket mounting arms 24 are arranged at intervals in the circumferential direction. The intervals in the circumferential direction of the sprocket mounting arm 24 are equal intervals. Here, an example in which the circumferential intervals of the sprocket mounting arms 24 are equal is shown, but the circumferential intervals of the sprocket mounting arms 24 may be unequal intervals.

  The sprocket mounting arm 24 includes a first mounting portion 24a and a second mounting portion 24b. The first attachment portion 24 a is for attaching the first sprocket 14. The first mounting portion 24 a is formed at the tip of the sprocket mounting arm 24. The first attachment portion 24a is, for example, a through hole. The first sprocket 14 is fixed to the first mounting portion 24a.

  The second attachment portion 24 b is for attaching the second sprocket 16. The second mounting portion 24b is formed at the proximal end portion of the sprocket mounting arm 24 on the radially inner side from the first mounting portion 24a. The second attachment portion 24b is, for example, a bottomed screw hole. The second sprocket 16 is fixed to the second mounting portion 24b.

  The arm portion 22 is formed integrally with or separately from the sprocket mounting portion 20. Here, the arm portion 22 is formed integrally with the sprocket mounting portion 20. A pedal attachment portion 22 a is provided at the distal end portion of the arm portion 22. A pedal (not shown) can be attached to the pedal mounting portion 22a. A connecting hole 22 b is provided at the base end portion of the arm portion 22. The crankshaft 19 is coupled to the coupling hole 22b so as to be integrally rotatable.

<First sprocket>
As shown in FIGS. 2 to 5, the first sprocket 14 has a rotation center axis X. The first sprocket 14 includes a first sprocket body 30 (an example of a main body part), a first annular part 31 (an example of an annular part), and a plurality of teeth 32 (an example of a first tooth part and a second tooth part). The first speed change area 34 (see FIGS. 3 and 4; an example of the speed change area).

  The first sprocket body 30 is made of non-metal, for example, synthetic resin such as carbon fiber reinforced resin. The first procket body 30 is formed integrally with the first annular portion 31. As shown in FIGS. 2 to 4, the first sprocket main body 30 has a plurality of (for example, four) first fixing portions 30 a. The plurality of first fixing portions 30a are arranged at intervals in the circumferential direction.

  Each 1st fixing | fixed part 30a is a through-hole, for example. Each 1st fixing | fixed part 30a is arrange | positioned in the position facing each 1st attaching part 24a. In this state, the first fixing bolts 26 (see FIG. 1) are inserted through the first fixing portions 30a and the first attachment portions 24a and screwed into nut members (not shown). As a result, the first sprocket body 30 is fixed to the sprocket mounting arm 24.

  The first annular portion 31 is attached to the first sprocket body 30. Specifically, the first annular portion 31 is attached to the outer periphery of the first sprocket body 30. The first annular portion 31 is made of metal, for example, aluminum, titanium, or iron / stainless steel. A plurality of teeth 32 are provided on the outer periphery of the first annular portion 31.

  A plurality of teeth 32 (including first teeth 32 a and second teeth 32 b described later) are provided on the outer periphery of the first annular portion 31. Specifically, the plurality of teeth 32 (for example, 30 to 60) are arranged side by side in the circumferential direction on the outer periphery of the first annular portion 31, and are integrally formed on the outer peripheral portion of the first annular portion 31. The plurality of teeth 32 are made of metal, for example, aluminum, titanium, or iron / stainless steel.

  The plurality of teeth 32 include a plurality of first teeth 32a (an example of first teeth) and a plurality of second teeth 32b (an example of second teeth). The first teeth 32a and the second teeth 32b are arranged alternately in the circumferential direction, that is, adjacent to each other in the circumferential direction.

  The first teeth 32a are formed to be engageable with the outer link plate 2a. Specifically, the first teeth 32a are formed so as to be engageable between the axial directions of the pair of outer link plates 2a. The first teeth 32a are formed in a tapered shape so that the axial width gradually decreases toward the radially outer side. The axial direction includes a direction in which the rotation center axis X extends and a direction parallel to the rotation center axis X. The axial direction used here corresponds to a direction parallel to the rotation center axis X.

  As shown in FIG. 4, the first tooth 32a preferably has a first recess 32e (an example of a recess). The 1st recessed part 32e is provided in the corner part of the 1st tooth | gear 32a. The surface on the first side surface 14a side in the first recess 32e is preferably formed flush with the surface on the first side surface 14a side in the second tooth 32b. The surface of the first recess 32e on the second side surface 14b side is preferably formed flush with the surface of the second tooth 32b on the second side surface 14b side.

  Here, the first side surface 14a (see FIG. 1) is a front surface arranged on the outer side in the axial direction far from the bicycle frame when the crank assembly 10 is mounted on the bicycle. The second side surface 14b (see FIGS. 3 and 4) is a back surface arranged on the inner side in the axial direction near the bicycle frame.

  The first recess 32e is formed by press work such as forging. Here, although the example in case the 1st recessed part 32e is formed by press work is shown, the 1st recessed part 32e may be formed by cutting.

  As shown in FIG. 5, the first recess 32e is formed to face the end of the inner link plate 2b. Excessive interference between the first teeth 32a and the inner link plate 2b is avoided by the first recess 32e. Further, by providing the first recess 32e in the first tooth 32a, as shown in FIGS. 2, 4, and 5, the first tooth 32a (except for the first teeth 32a1 and 32a2 for shifting) has a diameter. When viewed from the outside in the direction, it is formed in a substantially + (plus) shape.

  Here, as shown in FIGS. 2 to 3, the plurality of first teeth 32 a include a plurality of (for example, two) first gear teeth 32 a 1 and a plurality of (for example, two) first gears for shifting. Teeth 32a2 are included. The first gear 32a1 for shifting is used for the downward shifting in which the chain 2 moves from the first sprocket 14 to the second sprocket 16. The first gear 32a2 for shifting is for the upward shifting in which the chain 2 moves from the second sprocket 16 to the first sprocket 14. The first gear 32a1 for shifting and the first tooth 32a2 for shifting are preferably formed in a substantially T shape when viewed from the outside in the radial direction by providing the first recess 32e as described above. .

  As shown in FIG. 5, the first tooth 32a has a first maximum axial width W1 (an example of a first axial chain engagement width). The first maximum axial width W1 is the width of the longest portion of the first tooth 32a in the axial direction. The first maximum axial width W1 is smaller than the first axial interval L1 in the pair of outer link plates 2a. The first maximum axial width W1 is larger than the second axial interval L2 in the pair of inner link plates 2b.

  The first axial interval L1 is the interval between the surfaces of the pair of outer link plates 2a facing each other in the axial direction. The second axial interval L2 is the interval between the surfaces of the pair of inner link plates 2b facing each other in the axial direction.

  As shown in FIGS. 2 to 4, the second teeth 32 b are formed to be engageable with the inner link plate 2 b. Specifically, the second teeth 32b are formed to be engageable between the axial directions of the pair of inner link plates 2b.

  The second teeth 32b are preferably formed in a substantially-(minus) shape when viewed from the radially outer side. The second teeth 32b are formed in a tapered shape so that the axial width gradually decreases toward the radially outer side.

  As shown in FIG. 5, the second teeth 32b have a second maximum axial width W2 (an example of a second axial chain engagement width). The second maximum axial width W2 is the width of the longest portion of the second tooth 32b in the axial direction. The second maximum axial width W2 is smaller than the second axial interval L2. The second maximum axial width W2 is smaller than the first maximum axial width W1.

  By processing the second teeth 32b as follows, the second teeth 32b are formed, and the above configuration is satisfied. The second teeth 32b are formed by deformation of the material. Specifically, the second teeth 32b are formed by pressing. More specifically, the second teeth 32b are formed by forging. Specifically, the second tooth 32b is formed by forging together with the first recess 32e. In this way, the second maximum tooth width W2 of the second tooth 32b is set by pressing the second tooth 32b, for example, forging.

  The first shift region 34 is provided for shifting the chain 2. The first speed change region 34 is a region in which the chain engages with the teeth 32 of the first sprocket 14 during the upshift operation from the second sprocket 16 to the first sprocket 14. The first shift region 34 is a region in which the chain is separated from the teeth 32 of the first sprocket 14 during a downward shift operation from the first sprocket 14 to the second sprocket 16.

  As shown in FIGS. 2 to 4, the first speed change region 34 includes a plurality of first speed change teeth 32 c. Here, a plurality of (for example, two) first gears 32a1 for shifting correspond to the first gears 32c. Further, two second teeth 32b adjacent to the first teeth 32a1 for each shift correspond to the first shift teeth 32c.

  As shown in FIGS. 2 and 3, the first speed change gear 32c has a first guide surface 32d. The first guide surface 32 d is for guiding the chain 2. The first guide surface 32d is provided on the first speed change gear 32c on the first side surface 14a (see FIG. 2) side or the second side surface 14b (see FIGS. 3 and 4) side of the first sprocket 14. The first guide surface 32d is formed in a concave shape so that the thickness gradually decreases toward the side portion of the first speed change gear 32c.

The first speed change region 34 preferably includes a first protrusion 36a and a second protrusion 36b.
The first protrusion 36a and the second protrusion 36b are provided on the first sprocket body 30 so as to be able to support the chain 2. Here, the pair of first protrusions 36a and the second protrusions 36b are arranged at intervals in the circumferential direction.

  The first protrusion 36 a is provided to protrude from the second side surface 14 b of the first sprocket body 30 in order to guide the chain 2 to the teeth 32 of the first sprocket 14. For example, the first protrusion 36a guides the chain 2 to the second teeth 32b indicated by hatching in FIG. The second protrusion 36b is provided to protrude from the second side surface 14b of the first sprocket body 30 in order to guide the chain 2 to the first protrusion 36a.

  Further, as shown in FIGS. 3 and 4, the first shift region 34 includes a stepped portion 38. The step portion 38 is for facilitating engagement of the chain 2 supported by the first protrusion 36 a with the teeth 32 of the first sprocket 14. The stepped portion 38 is provided radially inward from the bottom of the plurality of teeth 32 on the first side surface 14a. Further, the stepped portion 38 is provided on the downstream side in the traveling rotation direction R with respect to the first protrusion 36a. The stepped portion 38 is formed to be recessed in a substantially triangular shape.

<Second sprocket>
As shown in FIGS. 4 and 6, the second sprocket 16 has a rotation center axis Y. The rotation center axis Y is concentric with the rotation center axis X. The second sprocket 16 includes a second sprocket body 40 (an example of a main body part), a second annular part 41 (an example of an annular part), and a plurality of teeth 42 (an example of a first tooth part and a second tooth part). , A second shift region 44 (an example of a shift region).

  The second sprocket body 40 is made of metal, for example, aluminum, titanium, or iron / stainless steel. The second sprocket body 40 has a plurality of (for example, four) second fixing portions 40a. The plurality of second fixing portions 40a are arranged at intervals in the circumferential direction.

  Each 2nd fixing | fixed part 40a is a through-hole, for example. Each 2nd fixing | fixed part 40a is arrange | positioned in the position facing each 2nd attaching part 24b. In this state, the second fixing bolt 28 is inserted into each of the second fixing portions 40a and the second mounting portion 24b, and the second fixing bolt 28 is screwed into a nut member (not shown). As a result, the second sprocket body 40 is fixed to the sprocket mounting arm 24.

  The second annular portion 41 is provided on the outer periphery of the second sprocket body 40. The second annular portion 41 is made of metal, for example, aluminum, titanium, or iron / stainless steel. A plurality of teeth 42 are provided on the outer periphery of the second annular portion 41.

  A plurality of teeth 42 (including third teeth 42 a and fourth teeth 42 b described later) are provided on the outer periphery of the second annular portion 41. Specifically, the plurality of teeth 42 (for example, 20 to 40) are arranged side by side in the circumferential direction on the outer periphery of the second annular portion 41, and are integrally formed on the outer peripheral portion of the second annular portion 41. The plurality of teeth 42 are made of metal, for example, aluminum, titanium, or iron / stainless steel.

  The plurality of teeth 42 include a plurality of third teeth 42a (an example of first teeth) and a plurality of fourth teeth 42b (an example of second teeth). The third teeth 42a and the fourth teeth 42b are arranged alternately in the circumferential direction, that is, adjacent to each other in the circumferential direction.

  The third teeth 42a are formed to be engageable with the outer link plate 2a. Specifically, the third teeth 42a are formed to be engageable between the axial directions of the pair of outer link plates 2a. The third teeth 42a are formed in a tapered shape so that the axial width gradually decreases toward the radially outer side.

  As shown in FIG. 6, the third tooth 42a has a second recess 42e (an example of a recess). The 2nd recessed part 42e is provided in the corner part of the 3rd tooth | gear 42a. The surface of the second recess 42e on the first side surface 14a side is formed flush with the surface of the fourth tooth 42b on the first side surface 14a side. The surface on the second side surface 14b side in the second recess 42e is formed flush with the surface on the second side surface 14b side in the second tooth 32b.

  The second recess 42e is formed by press work such as forging. Here, an example in which the second recess 42e is formed by pressing is shown, but the second recess 42e may be formed by cutting.

  Similar to the first recess 32e described above, the second recess 42e is formed to face the end of the inner link plate 2b. Excessive interference between the third teeth 42a and the inner link plate 2b is avoided by the second recess 42e. Further, by providing the second recess 42e in the third tooth 42a, as shown in FIGS. 4 and 6, the third tooth 42a is formed in a substantially + (plus) shape when viewed from the outside in the radial direction. The

  As shown in FIG. 5, the third teeth 42a have a third maximum axial width W3 (an example of a first axial chain engagement width). The third maximum axial width W3 is the width of the portion in which the length of the third tooth 42a is the longest in the axial direction. The third maximum axial width W3 is smaller than the first axial interval L1. The third maximum axial width W3 is larger than the second axial interval L2 in the pair of inner link plates 2b.

  As shown in FIGS. 4 to 6, the fourth teeth 42b are formed so as to be engageable with the inner link plate 2b. Specifically, the fourth teeth 42b are formed to be engageable between the axial directions of the pair of inner link plates 2b.

  The fourth teeth 42b are formed in a substantially-(minus) shape when viewed from the outside in the radial direction. The fourth teeth 42b are formed in a tapered shape so that the axial width gradually decreases toward the radially outer side.

  As shown in FIG. 5, the fourth tooth 42b has a fourth maximum axial width W4 (an example of a second axial chain engagement width). The fourth maximum axial direction width W4 is the width of the longest portion of the fourth tooth 42b in the axial direction. The fourth maximum axial width W4 is smaller than the second axial interval L2. The fourth maximum axial width W4 is smaller than the third maximum axial width W3.

  By processing the fourth teeth 42b as follows, the fourth teeth 42b are formed so that the above-described configuration is satisfied. The fourth teeth 42b are formed by deformation of the material. Specifically, the fourth teeth 42b are formed by pressing. More specifically, the fourth teeth 42b are formed by forging. As described above, the fourth tooth 42b is press-formed, for example, forged to set the fourth maximum axial width W4 of the fourth tooth 42b.

  The second shift region 44 is provided for shifting the chain 2. The second shift region 44 is configured so that the chain is connected to the teeth 42 of the first sprocket 14 during the upward shift operation from the second sprocket 16 to the first sprocket 14 or during the downward shift operation from the first sprocket 14 to the second sprocket 16. Or a region away from the teeth 42 of the first sprocket 14.

  The second shift region 44 includes a plurality of (for example, two) second shift teeth 42c. The second transmission teeth 42c are provided at intervals in the circumferential direction. The second speed change gear 42c has a second guide surface 42d. The second guide surface 42d is provided on the fourth side surface 16b (see FIG. 6) side opposite to the third side surface 16a (see FIG. 1), and guides the chain 2. The second guide surface 42d is formed in a concave shape so that the thickness gradually decreases toward the side of the second speed change gear 42c.

  Here, the third side surface 16a of the second sprocket 16 is a front surface disposed on the outside in the axial direction far from the bicycle frame when the crank assembly 10 is mounted on the bicycle. The fourth side surface 16b is a back surface arranged on the inner side in the axial direction close to the bicycle frame.

  Here, an example in which the second shift region 44 does not include the protrusions and the recesses of the first shift region 34 is shown, but the second shift region 44 includes at least one of the protrusions and the recesses. Also good.

<Speed change operation in crank assembly>
In the crank assembly 10 having such a configuration, when an upshift operation is performed from the second sprocket 16 to the first sprocket 14 by a front derailleur (not shown), the crank assembly 10 rotates in the traveling rotation direction R. In this state, when the front derailleur moves from a position facing the second sprocket 16 to a position facing the first sprocket 14, the chain 2 is separated from the teeth of the second sprocket 16. Then, the chain 2 is supported by the second protrusion 36b and moves outward in the radial direction. Then, the chain 2 is supported by the first protrusion 36 a via the step portion 38 of the first speed change region 34, and is guided and engaged with the teeth 32 of the first sprocket 14.

  On the other hand, when the downshift operation is performed from the first sprocket 14 to the second sprocket 16 by the front derailleur, the crank assembly 10 is rotated in the traveling rotation direction R. In this state, when the front derailleur moves from a position facing the first sprocket 14 to a position facing the second sprocket 16, the chain 2 is separated from the teeth of the first sprocket 14. Then, the chain 2 is guided toward the teeth 42 of the second sprocket 16 and engaged with the teeth 42.

Second Embodiment
As shown in FIG. 1, a bicycle crank assembly 110 according to the second embodiment includes a crank arm 12, a first sprocket 114 (an example of a bicycle sprocket), and a second sprocket 116 (an example of a bicycle sprocket). . The first sprocket 114 and the second sprocket 116 are an example of a bicycle sprocket assembly.

  The configuration of the second embodiment is substantially the same as the configuration of the first embodiment except for the configurations of the first sprocket 114 and the second sprocket 116. For this reason, only the structure of the 1st sprocket 114 and the 2nd sprocket 116 is demonstrated here, and description of the structure substantially the same as the structure of 1st Embodiment is abbreviate | omitted. In addition, about the structure abbreviate | omitted here, it applies to description of the structure of 1st Embodiment. Moreover, the same code | symbol is attached | subjected about the structure similar to 1st Embodiment.

  The first sprocket 114 includes a first sprocket body 30 (an example of a main body part), a first annular part 31 (an example of an annular part), and a plurality of teeth 132 (an example of a first tooth part and a second tooth part). , A first shift region 34 (an example of a shift region).

  Here, the configuration of the first sprocket body 30, the configuration of the first annular portion 31, and the configuration of the first shift region 34 are substantially the same as the configuration of the first embodiment, and thus description thereof is omitted here. . Moreover, about the structure of the some tooth | gear 132, only the structure different from the structure of 1st Embodiment is demonstrated below.

As shown in FIG. 7, each of the plurality of first teeth 132a (an example of the first teeth) included in the plurality of teeth 132 includes a first body portion 132ab , a first recess 32e, and a first addition portion 132c. Have. Since the first recess 32e has the same configuration as that of the first embodiment, the description thereof is omitted here.

The first main body portion 132ab is provided in the first annular portion 31. Specifically, the first main body portion 132ab is formed integrally with the first annular portion 31 so as to protrude outward in the radial direction from the first annular portion 31. The first body portion 132ab has a surface 20a on the first side surface 14a side and a back surface 20b on the second side surface 14b side. The back surface 20b is a surface opposite to the front surface 20a in the axial direction of the rotation center axis X.

The first adding unit 132c, in order to increase the width of the first body portion 132ab, is attached to the first body portion 132ab. Specifically, the first additional portion 132c is attached to each of the front surface 20a and the back surface 20b of the first main body portion 132ab . Thus, by attaching the first additional portion 132c to the front surface 20a and the back surface 20b of the first main body portion 132ab , the first maximum axial width W1 is set to a predetermined width. The first additional portion 132c is made of metal, for example, aluminum, titanium, or iron / stainless steel. The first additional portion 132c is attached to the first teeth 132a by adhesion, diffusion bonding, caulking, or casting.

Here, an example is shown in which the first additional portion 132c is attached to each of the front surface 20a and the back surface 20b of the first main body portion 132ab . Instead , the first maximum axial width W1 may be set by attaching the first additional portion 132c only to the front surface 20a or only the back surface 20b of the first main body portion 132ab .

  The second sprocket 116 includes a second sprocket body 40 (an example of a main body part), a second annular part 41 (an example of an annular part), and a plurality of teeth 142 (an example of a first tooth part and a second tooth part). , A second shift region 44 (an example of a shift region).

  Here, the configuration of the second sprocket main body 40, the configuration of the second annular portion 41, and the configuration of the second shift region 44 are substantially the same as the configuration of the first embodiment, and thus the description thereof is omitted here. . Moreover, about the structure of the some tooth | gear 142, only the structure different from the structure of 1st Embodiment is demonstrated below.

Each of the plurality of third teeth 142a (an example of the first teeth) included in the plurality of teeth 142 includes a second main body portion 142b and a second addition portion 142c. The configurations of the second main body portion 142b and the second additional portion 142c are substantially the same as the configurations of the first main body portion 132ab and the first additional portion 132c described above. That is, the third maximum axial width W3 is set to a predetermined width by attaching the second additional portion 142c to the front surface 20a and the back surface 20b of the second main body portion 142b.

<Other embodiments>
As mentioned above, although one Embodiment of this invention was described, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the summary of invention. In particular, a plurality of embodiments and modifications described in this specification can be arbitrarily combined as necessary.

  (A) In the first and second embodiments, the two front sprockets 14 and 16 (114 and 116) are exemplified as the bicycle sprocket assembly, but the present invention is not limited to this. The present invention is also applicable to a bicycle sprocket assembly including only one front sprocket that does not have a speed change region.

  (B) In the first and second embodiments, an example in which the second sprocket body 40 and the plurality of teeth 42 and 142 are integrally formed has been shown, but the present invention is not limited to this. The second sprocket body 40 and the plurality of teeth 42 and 142 may be separate bodies. For example, the plurality of teeth 42 and 142 may be made of metal, and the second sprocket body 40 may be made of nonmetal. In this case, the weight can be reduced by using aluminum, titanium, or iron / stainless steel as the metal and using a synthetic resin such as carbon fiber reinforced resin as the nonmetal.

  (C) In the first and second embodiments, the portions where the first teeth 32a, 132a and the second teeth 32b engage with the chain roller 2c, and the third teeth 42a, 142a and the fourth teeth 42b are chain rollers. The portion engaged with 2c may be configured as shown in FIG.

  This configuration is substantially the same in the first sprockets 14 and 114 and the second sprockets 16 and 116. For this reason, this structure is demonstrated here using the 1st tooth | gear 232a and the 2nd tooth | gear 232b of the 1st sprocket 14,114.

  The chain roller 2c can be engaged between the first teeth 232a and the second teeth 232b (see FIGS. 1 and 5). As shown in FIG. 8, each of the first tooth 232 a and the second tooth 232 b has a drive surface 233 and a non-drive surface 234.

  Since this configuration is substantially the same for the first tooth 232a and the second tooth 232b, the first tooth 232a will be described here.

Each of the first teeth 232a and the second teeth 232b has a surface 20a on the first side surface 14a side, a back surface (not shown) on the second side surface 14b side, a driving surface 233, and a non-driving surface 234. The back surface 20b is a surface opposite to the front surface 20a in the axial direction of the rotation center axis X (direction perpendicular to the paper surface of FIG. 8).

  The drive surface 233 is a surface that connects the front surface 20a and the back surface in the axial direction on the downstream side in the traveling rotation direction R. The drive surface 233 includes a contact point CP and a first extension portion 233a (an example of a drive surface extension portion). The contact point CP is a portion where the chain roller 2c comes into contact. Specifically, the contact point CP is a point where the chain roller 2c contacts the driving surface 233 during driving.

  The first extension portion 233a is formed integrally with the drive surface 233. The first extending portion 233a extends in the circumferential direction on the radially outer side from the contact point CP. Specifically, the first extending portion 233a protrudes downstream in the traveling rotation direction R on the radially outer side from the contact point CP.

  The non-driving surface 234 is a surface that connects the front surface 20a and the rear surface in the axial direction on the upstream side in the traveling rotation direction R. For example, the non-driving surface 234 is formed symmetrically with the driving surface 233 with respect to a straight line CL that connects the rotation center axis X and the center position in the circumferential direction of the first tooth 232a (second tooth 232b). . The non-drive surface 234 may be formed asymmetrically with the drive surface 233 with respect to a straight line CL connecting the rotation center axis X and the center position in the circumferential direction of the first tooth 232a (second tooth 232b).

  The non-driving surface 234 includes a second extending portion 234a (an example of a non-driving surface extending portion). The movement of the chain roller 2c to the outside in the radial direction is suppressed by the second extending portion 234a. The second extending portion 234a is formed integrally with the non-driving surface 234. Here, as described above, since the non-driving surface 234 is formed in line symmetry with the driving surface 233, the second extending portion 234a extends in the circumferential direction on the opposite side to the first extending portion 233a. Put out. That is, the second extending portion 234a extends in the circumferential direction, for example, upstream in the traveling rotation direction R.

  Thereby, the driving force of the first sprocket 14 can be reliably transmitted to the chain roller 2c, that is, the chain 2 by the driving surface 233. Further, the drive surface 233 and the non-drive surface 234 can reliably suppress the movement of the chain roller 2c to the outside in the radial direction.

  Here, an example in which each of the first tooth 232a and the second tooth 232b has a driving surface 233 and a non-driving surface 234 is shown. Instead, only the first tooth 232a or only the second tooth 232b may be configured to have the drive surface 233 and the non-drive surface 234. Further, the first tooth 232a and / or the second tooth 232b may be configured to have only the driving surface 233 or only the non-driving surface 234.

(D) In the first and second embodiments, an example in which the front sprockets 14 and 16 are mounted on the crankshaft 19 through the crank arm 12 so as not to move is shown. Instead, the front sprockets 14 and 16 may move along the crankshaft 19 (rotation center axis X). Alternatively, only one front sprocket 14 may be used and the front sprocket 14 may be moved along the crankshaft 19 (rotation center axis X).

(E) The front sprockets 14 and 16 shown in the first and second embodiments may form an outline by a 3D printer, and then the second teeth 32b and the fourth teeth 42b may be formed by press working such as forging. Good.

  (F) In the first and second embodiments, the example in which the first teeth 32a and 132a and the third teeth 42a and 142a are formed in a substantially + shape is shown. It is not limited. For example, at least a part of the first teeth 32a and the third teeth 42a may have other shapes such as rhombus, trapezoid, triangle, hexagon, and octagon.

  As shown in FIG. 10, the first teeth 332a and / or the third teeth 342a are preferably octagonal when viewed from the radial direction of the bicycle sprocket. In this case, a tooth shape that can avoid excessive interference between the first teeth 332a and / or the third teeth 342a and the inner link plate 2b and that securely holds the outer link plate 2a is formed by pressing, for example, forging. easy.

  Here, the octagonal shape is not limited to a regular octagonal shape, and may be any shape as long as the shape has eight sides. Further, the eight sides constituting the octagon are not limited to a straight line but may be a curve having a gentle curvature.

  Specifically, as shown in FIGS. 9 and 10, when the first teeth 332a and the third teeth 342a have the above octagonal shape, the first teeth 332a and the third teeth 342a have the first surface 352a, It has a second surface 352b, a third surface 352c, and an inclined portion 353.

  The first surface 352a is a surface on the first side surface 14a side of the first sprocket 14 in the first tooth 332a, and a surface on the third side surface 16a side of the second sprocket 16 in the third tooth 342a.

  The second surface 352b is a surface on the second side surface 14b side of the first sprocket 14 in the first tooth 332a, and a surface on the fourth side surface 16b side of the second sprocket 16 in the third tooth 342a.

  The third surface 352c extends in the circumferential direction between the axial directions of the first surface 352a and the second surface 352b. The third surface 352c includes a drive surface 352d, a non-drive surface 352e, and a tip surface 352f that connects the drive surface 352d and the non-drive surface 352e in the circumferential direction. The inclined portion 353 is for avoiding excessive interference with the inner link plate 2b. The inclined portion 353 includes a first chamfered surface 353a, a second chamfered surface 353b, a third chamfered surface 353c, and a fourth chamfered surface 353d.

The first chamfered surface 353a is formed from the first surface 352a to the third surface 352c on the driving side. The second chamfered surface 353b is formed from the second surface 352b to the third surface 352c on the driving side. The third chamfered surface 353c is formed from the first surface 352a to the third surface 352c on the non-driving side. The fourth chamfered surface 353d is formed from the second surface 352b to the third surface 352c on the non-driving side.

  In other words, the first chamfered surface 353a is formed at a corner portion constituted by the first surface 352a and the third surface 352c on the driving side. The second chamfered surface 353b is formed at a corner portion constituted by the second surface 352b and the third surface 352c on the driving side. The third chamfered surface 353c is formed at a corner portion constituted by the first surface 352a and the non-driving side third surface 352c. The fourth chamfered surface 353d is formed in a corner portion constituted by the second surface 352b and the non-driving side third surface 352c.

  Here, since the driving side of the first teeth 332a and the third teeth 342a tends to interfere with the inner link plate 2b more excessively than the non-driving side, the first chamfered surface 353a formed on the driving side. The second chamfered surface 353b preferably has a larger area than the third chamfered surface 353c and the fourth chamfered surface 353d formed on the non-driving side.

  By the first to fourth chamfered surfaces 353a, 353b, 353c, and 353d, excessive interference between the first teeth 332a and the third teeth 342a and the inner link plate 2b can be avoided. Further, the first to fourth chamfered surfaces 353a, 353b, 353c, and 353d have different shapes from the concave portions of the first and second embodiments, and are inclined surfaces constituted by straight lines or gentle curves. It is easy to form by processing such as forging.

  When the first teeth 332a and the third teeth 342a have an octagonal shape, the first axial contact width L3 at which the drive surfaces of the first teeth 332a and the third teeth 342a contact the chain roller 2c is the second tooth It is preferable that the driving surfaces of 332b and the fourth teeth 342b have substantially the same length as the second axial contact width L4 that contacts the chain roller 2c.

  (G) In the first and second embodiments, an example in which the first teeth 32a and 132a are formed in a substantially T shape has been described, but the present invention is not limited to this. For example, a part of the first teeth 32a may be other shapes such as a diamond shape, a trapezoidal shape, a triangular shape, a hexagonal shape, and an octagonal shape.

  (H) In the first and second embodiments, the first speed change region 34 has the second protrusion 36b, but the second protrusion 36b may not be provided.

  (I) In the first and second embodiments, the number of the plurality of sprocket mounting arms 24 is four, but the number of sprocket mounting arms is not limited to four.

  (J) In the first and second embodiments, the first transmission region 34 and the second transmission region 44 of each of the first sprocket 14 and the second sprocket 16 include the second teeth 32b having the − (minus) shape and the second gear 32b. Four teeth 42b may be included.

  (K) In the said 2nd Embodiment, although the example in case the additional part of the 1st tooth | gear 32a was metal was shown, the additional part may be non-metallic. For example, when the additional portion is made of non-metal, the additional portion is attached to the first tooth by bonding or integral molding. In this case, noise caused by contact between the chain and the sprocket teeth during pedaling can be reduced.

  (L) At least one of the first teeth 32a and 132a and the second teeth 32b and 132b of the bicycle sprocket in the present invention may preferably have a plating layer.

  For example, when the first teeth 32a and 132a and the second teeth 32b and 132b are made of aluminum, the plating layer is preferably a nickel plating layer for the purpose of wear resistance. When the first teeth 32a and 132a and the second teeth 32b and 132b are made of iron, the plating layer is preferably a nickel chrome plating layer for the purpose of rust prevention.

  When the first teeth 32a, 132a and the second teeth 32b, 132b are made of iron, the first teeth 32a, 132a and the second teeth 32b, 132b are electrodeposited coating layers for the purpose of rust prevention and coloring. It is also preferable to have

  (M) In the first and second embodiments, the first sprocket 14 includes the first sprocket body 30 made of synthetic resin, the first annular portion 31 made of metal, and the first tooth portion 32b. An example of the case is shown.

  Instead, the first sprocket 14 may be made of metal, and the first sprocket body 30, the first annular portion 31, and the first tooth portion 32b may be integrally molded. In this case, the first sprocket body 30, the first annular portion 31, and the first tooth portion 32b are made of metal such as aluminum, titanium, or iron / stainless steel.

  An example of the first sprocket 314 configured in this manner is shown in FIG. FIG. 11 has substantially the same configuration as that of the first and second embodiments, and the same reference numerals as those of the first embodiment are given to representative configurations.

  (N) Instead of the first sprockets 14 and 114 of the first and second embodiments, the first sprocket 214 may be configured as shown in FIGS. 12A and 12B. In FIGS. 12A and 12B, substantially the same configurations as those of the first and second embodiments are expressed using the reference numerals of the first embodiment.

  In the first sprocket 214, the first through hole 130 a is provided in the first sprocket body 30. A second through hole 130 b is provided in the first annular portion 31. A ring member 130c, for example, a washer is disposed in the first through hole 130a. Specifically, the first sprocket body 30 includes the first annular portion 31 and the ring member 130c so that the inner peripheral surface of the ring member 130c is substantially flush with the inner peripheral surface of the second through hole 130b. And is integrally molded.

  When the first sprocket 214 is configured in this way, the first fixing bolts 26 are inserted into the ring members 130c, the second through holes 130b, and the first mounting portions 24a, and nut members (not shown). ). As a result, the first sprocket body 30 is fixed to the sprocket mounting arm 24.

  (O) In the first and second embodiments, an example in which the second teeth 32b of the first sprocket 14 are formed together with the first recesses 32e by press work, for example, forging, has been shown. Instead, as shown in FIGS. 13A to 13D, the second teeth 32b may be formed by press working (for example, forging) and a cutting process. Note that FIGS. 13A to 13D schematically represent each process for ease of explanation.

  In this case, the second teeth 32b include a first pressing step (see FIG. 13B), a cutting step after the first pressing step (see FIG. 13C), and a second pressing step after the cutting step (FIG. 13D). For example).

As shown in FIG. 13D, the second tooth 32b has a fifth surface 52a (an example of the first surface) and a sixth surface 52b (an example of the first surface). For example, the fifth surface 52a is formed on the first side surface 14a (see FIG. 2) side of the first sprocket 14 in the second tooth 32b . The sixth surface 52b is a surface located on the opposite side to the fifth surface 52a in the axial direction parallel to the rotation center axis X. For example, the sixth surface 52b is formed on the second side surface 14b (see FIG. 4) side of the first sprocket 14 in the second tooth 32b.

  Specifically, as shown in FIG. 13A, in an initial state, a surface (a first pressing portion 152a described later) on which a fifth surface 52a of the second tooth portion 32b is configured and a surface on which a sixth surface 52b is configured. (Second pressing portion 152c described later) is formed on substantially the same surface as the outer surface of the first annular portion 31 of the first sprocket 14.

  The first pressing step is a step of pressing the fifth surface 52a side of the second tooth 32b. As shown in FIG. 13B, in the first pressing step, the fifth surface 52a side of the second tooth 32b is pressed by the pressing member A of the pressing device (not shown) with the first annular portion 31 fixed. .

  Here, the 1st press part 152a which the press member A presses is a part in which the 2nd tooth | gear 32b and the 1st recessed part 32e are formed. As described above, when the pressing member A presses the first pressing portion 152a, the fifth surface 52a of the second tooth portion 32b is formed, and the sixth surface 52b side is substantially opposite to the first pressing portion 152a. The located part protrudes. Hereinafter, this portion is referred to as a protruding portion 152b.

  The cutting step is a step of cutting the protruding portion 152b protruding in the axial direction by the first pressing step on the sixth surface 52b side of the second tooth 32b. As shown in FIG. 13C, in the cutting process, the protruding portion 152 b formed on the sixth surface 52 b side is cut by the cutting device B. Specifically, the cutting device B cuts the surface after the projecting portion 152b is cut so as to be substantially flush with the outer surface of the first annular portion 31.

  The second pressing step is a step of pressing the sixth surface 52b side of the second tooth 32b. As shown in FIG. 13D, in the second pressing step, the sixth surface of the second tooth 32b is in a state where the mold D for forming the outer shape of the second tooth 32b is in contact with the first pressing portion 152a. The 52b side is pressed by the pressing member C of the pressing device.

  Here, the 2nd press part 152c which the press member C presses is a part in which the 2nd tooth | gear 32b and the 1st recessed part 32e are formed. As described above, when the pressing member C presses the second pressing portion 152c, the sixth surface 52b of the second tooth portion 32b is formed. Further, a tooth tip 52c of the second tooth portion 32b including the fifth surface 52a and the sixth surface 52b is formed.

  As described above, the second teeth 32b can be formed by using the first pressing step, the cutting step, and the second pressing step. In addition, after the 2nd tooth | gear 32b is formed as mentioned above, the grinding | polishing process for adjusting the shape of the 2nd tooth | gear 32b, and the plating process (preferably nickel plating process) which raises the abrasion resistance of the 2nd tooth | gear 32b are performed. , May be added selectively.

  Here, an example in which the second teeth 32b are formed by pressing and cutting processes is shown, but the fourth teeth 42b of the second sprocket 16 may be formed in the same manner.

  (P) In the first and second embodiments and the other embodiments, the front sprockets 14 and 16 are exemplified as bicycle sprockets, but the present invention is not limited to this. The present invention is also applicable to a rear sprocket.

  Widely applicable to bicycle sprockets and bicycle sprocket assemblies.

2 Chain 2a Outer link plate 2b Inner link plate 2c Chain roller 10, 110 Bicycle crank assembly 14, 114 First sprocket 16, 116 Second sprocket 32a, 132a First tooth 32b, 132b Second tooth 34 First shift region 32e 1st recessed part 42a, 142a 3rd tooth | gear 42b 4th tooth | gear 42e 2nd recessed part
132ab first main body portion 132c first additional portion 142b second main body portion 142c second additional portion CP contact point L1 first axial interval L2 second axial interval W1 first maximum axial width W2 second maximum axial width W3 Third maximum axial width W4 Fourth maximum axial width

Claims (31)

A bicycle sprocket having a rotation center axis,
A first tooth having a first axial chain engagement width that is smaller than a first axial interval in an outer link of a bicycle chain and larger than a second axial interval in an inner link connected to the outer link;
A second tooth having a second axial chain engagement width smaller than the second axial spacing;
With
The second tooth is formed by deformation of the material,
Bicycle sprocket. The second teeth are formed by pressing.
The bicycle sprocket according to claim 1. The first tooth has a recess for avoiding excessive interference with the inner link,
The recess is formed by pressing.
The bicycle sprocket according to claim 1 or 2. The first tooth has a recess for avoiding excessive interference with the inner link,
The recess is formed by cutting.
The bicycle sprocket according to claim 1 or 2. The first tooth has a main body part and an additional part attached to the main body part in order to widen the width of the main body part,
The first axial chain engagement width is a width obtained by attaching the additional part to the main body part,
The bicycle sprocket according to any one of claims 1 to 4. The additional portion is made of metal and attached to the first tooth by adhesion, diffusion bonding, caulking, or casting.
The bicycle sprocket according to claim 5. The additional part is made of non-metal and is attached to the first tooth by adhesion or integral molding.
The bicycle sprocket according to claim 5. Each of the first tooth and the second tooth has a drive surface,
The drive surface includes a contact point with which the chain roller contacts;
The drive surface is formed with a drive surface extending portion extending in the circumferential direction on the radially outer side from the contact point.
The bicycle sprocket according to any one of claims 1 to 7. Each of the first tooth and the second tooth further has a non-drive surface,
The non-driving surface is formed with a non-driving surface extending portion that extends in the circumferential direction in order to suppress the movement of the chain roller radially outward.
The bicycle sprocket according to claim 8. Each of the first tooth and the second tooth has a drive surface and a non-drive surface,
The drive surface includes a contact point with which the chain roller contacts;
The drive surface is formed with a drive surface extending portion extending in the circumferential direction on the radially outer side from the contact point,
The non-driving surface is formed with a non-driving surface extending portion that extends in the circumferential direction in order to suppress the movement of the chain roller radially outward.
The bicycle sprocket according to any one of claims 1 to 7. A shift region for shifting the chain during a shift,
The bicycle sprocket according to any one of claims 1 to 10, further comprising: A metal annular portion in which the first teeth and the second teeth are provided on the outer periphery;
A non-metallic main body attached to the inner periphery of the annular portion;
The bicycle sprocket according to any one of claims 1 to 11, further comprising: The press work is forging.
The bicycle sprocket according to any one of claims 2 to 12. The second tooth is formed by a pressing process and a cutting process.
The bicycle sprocket according to any one of claims 1 to 13. The second tooth is formed by a first pressing step, a cutting step after the first pressing step, and a second pressing step after the cutting step.
The bicycle sprocket according to any one of claims 1 to 14. The second tooth has a first surface and a second surface located on the opposite side of the first surface in an axial direction parallel to the rotation center axis.
The first pressing step is a step of pressing the first surface side of the second tooth,
The second pressing step is a step of pressing the second surface side of the second tooth.
The bicycle sprocket according to claim 15. The cutting step is a step of cutting a protruding portion protruding in the axial direction by the first pressing step on the second surface side of the second tooth.
The bicycle sprocket according to claim 16. A bicycle sprocket having a rotation center axis,
A first tooth having a first axial chain engagement width that is smaller than a first axial interval in an outer link of a bicycle chain and larger than a second axial interval in an inner link connected to the outer link;
A second tooth having a second axial chain engagement width smaller than the second axial spacing;
With
The first tooth has a substantially octagonal shape when viewed from the outside in the radial direction.
Bicycle sprocket. The first axial contact width where the driving surface of the first tooth contacts the chain roller is formed to be substantially the same length as the second axial contact width where the driving surface of the second tooth contacts the chain roller. The
The bicycle sprocket according to claim 18. A bicycle sprocket having a rotation center axis,
A first tooth having a first axial chain engagement width that is smaller than a first axial interval in an outer link of a bicycle chain and larger than a second axial interval in an inner link connected to the outer link;
A second tooth having a second axial chain engagement width smaller than the second axial spacing;
With
The first tooth has an inclined portion for avoiding excessive interference with the inner link,
Bicycle sprocket. The first tooth further includes a first surface, a second surface, and a third surface extending in a circumferential direction between the axial directions of the first surface and the second surface,
The inclined portion includes a first chamfered surface formed from the first surface to the third surface on the driving side, a second chamfered surface formed from the second surface to the third surface on the driving side, A third chamfered surface formed from the first surface to the third surface on the non-driving side, and a fourth chamfered surface formed from the second surface to the third surface on the non-driving side,
The bicycle sprocket according to claim 20. The first axial contact width where the driving surface of the first tooth contacts the chain roller is formed to be substantially the same length as the second axial contact width where the driving surface of the second tooth contacts the chain roller. The
The bicycle sprocket according to claim 20 or 21. A bicycle sprocket having a rotation center axis,
A first tooth having a first axial chain engagement width that is smaller than a first axial interval in an outer link of a bicycle chain and larger than a second axial interval in an inner link connected to the outer link;
A second tooth having a second axial chain engagement width smaller than the second axial spacing;
With
At least one of the first teeth and the second teeth has a plating layer,
Bicycle sprocket. The first teeth and the second teeth are made of aluminum, and the plating layer is a nickel plating layer.
The bicycle sprocket according to claim 23. The first teeth and the second teeth are made of iron, and the plating layer is a nickel chrome plating layer.
The bicycle sprocket according to claim 23. The sprocket according to any one of claims 1 to 25,
A bicycle sprocket assembly comprising: The sprocket is a single front sprocket,
27. A bicycle sprocket assembly according to claim 26. The sprocket is movable along a rotation center axis.
The bicycle sprocket assembly according to claim 27. The sprocket is a plurality of front sprockets,
The bicycle sprocket assembly according to any one of claims 26 to 28. The sprocket is movable along a rotation center axis.
30. The bicycle sprocket assembly according to claim 29. The sprocket is a rear sprocket.
27. A bicycle sprocket assembly according to claim 26.

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