Hub for spoke wheel

Abstract

To provide a hub for a spoke wheel capable of suppressing an increase in weight.SOLUTION: Recesses 44 are formed between neighboring spoke attachment holes 40 in an inner peripheral surface 45 of a peripheral wall 38, and are recessed radially outward from the positions of the spoke attachment holes 40. Thereby, a thickness of the peripheral wall 38 is reduced and an unnecessary thickness of the peripheral wall 38 is reduced, so that a weight of the hub 14 is reduced. In addition, since the recess 44 are each formed of a flat surface and a smooth curved surface, and neighboring protrusions 42 are connected via a smooth curved surface, occurrence of stress concentration is suppressed, and a decrease in strength of the hub 14 is suppressed.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a hub for a spoke wheel used for wheels of motorcycles and the like.

Background Art

[0002] A spoke wheel used for wheels of motorcycles or the like includes a hub through which an axle is inserted, a rim disposed on the outer peripheral side of the hub, and a plurality of spokes connecting between the hub and the rim. For example, the wheel described in Patent Document 1 is such a wheel. Patent Document 1 describes a hub structure and a manufacturing method capable of reducing the size of a disk mounting portion for mounting a brake disk on the outer periphery of the hub.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, a plurality of spoke mounting holes (spoke receiving holes) for mounting spokes are formed in the circumferential direction on the circumferential wall of the flange provided on the hub described in Patent Document 1. Here, when the circumferential wall intervening between adjacent spoke mounting holes in the circumferential direction is formed thick, there arises a problem of an increase in the weight of the hub.

[0005] The present invention has been made in view of the above circumstances, and an object thereof is to provide a hub for a spoke wheel capable of suppressing an increase in weight.

Means for Solving the Problems

[0006] The spoke wheel according to one aspect of the present invention includes a boss portion having a boss hole through which an axle is inserted, a peripheral wall formed on the radially outer side of the boss portion, a plurality of spoke mounting holes formed on the inner peripheral surface of the peripheral wall so as to be arranged in the circumferential direction and to which the ends of the spokes are fixed, and a recess formed between at least some adjacent spoke mounting holes on the inner peripheral surface of the peripheral wall and recessed radially outward from the position of the spoke mounting holes.

[0007] According to the above aspect, since a recess having a shape recessed radially outward from the position of the spoke mounting holes is provided between at least some adjacent spoke mounting holes on the inner peripheral surface of the peripheral wall, it is possible to suppress an increase in the weight of the hub by eliminating the flash formed on the peripheral wall by the amount of the recess formed.

[0008] In the above aspect, preferably, the recess is formed in an arc shape when viewed from the direction of the center line of the boss hole. According to this aspect, since the inner peripheral surface of the peripheral wall is formed into a curved surface by forming the recess in an arc shape, it is possible to suppress the occurrence of stress concentration.

Effect of the Invention

[0009] According to the present invention, it becomes possible to provide a hub for a spoke wheel that can suppress an increase in weight.

Brief Description of the Drawings

[0010]

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Mode for Carrying Out the Invention

[0011] [Embodiment 1] FIG. 1 is a perspective view showing the appearance of a spoke wheel 10 (hereinafter, wheel 10) to which the present invention is applied, and FIG. 2 is a view seen from the direction of the center line CL (hereinafter, center line CL direction) of the axle 12 inserted through the wheel 10 in FIG. 1 and a cross-sectional view of the wheel 10. Since the wheel 10 is vertically symmetric about the center line CL, the lower half is omitted in FIG. 2.

[0012] The wheel 10 includes a hub 14 through which an axle 12 is inserted, an annular rim 16 disposed on the outer peripheral side of the hub 14, and a plurality of spokes 18 connecting between the hub 14 and the rim 16.

[0013] The hub 14 is rotatably held by a front fork (not shown) via the axle 12. The rim 16 is formed in an annular shape, and a tire (not shown) is mounted on the outer periphery of the rim 16. The spokes 18 extend radially from the hub 14, with one end fixed to the hub 14 and the other end fixed to the rim 16. The spokes 18 are made of, for example, hard steel wire.

[0014] FIG. 3 is a view of the hub 14 and the spokes 18 as seen from the direction of the center line CL (a view seen along the center line CL direction, a center line CL direction view), and is a view for explaining the shape of a first flange 24 of the hub 14 described later. FIG. 4 is a perspective view of FIG. 3, and FIG. 5 is a cross-sectional view of the hub 14 cut along the cutting line A in FIG. 3. Further, FIG. 6 is a perspective view of the hub 14 and is a view for explaining the shape of a second flange 26 of the hub 14 described later. FIG. 7 is a perspective view of the second flange 26 of the hub 14 as seen from an angle different from FIG. 6. FIG. 8 is a view of the second flange 26 as seen from the direction of the center line CL. FIG. 9 is a cross-sectional view of the hub 14 cut along the cutting line B in FIG. 8. Note that in FIGS. 6 to 9, the spokes 18 are shown in a removed state. Also, in FIGS. 6 to 9, views in which only the shape of an annular space 32 formed in the second flange 26 and described later is drawn in solid lines are shown as reference figures in FIGS. 14 to 17, respectively.

[0015] As shown in FIGS. 3 to 9, the hub 14 includes a cylindrical inner cylinder portion 20 (see FIG. 5) through which the axle 12 (see FIGS. 1 and 2) is inserted, a cylindrical outer cylinder portion 22 disposed on the outer peripheral side of the inner cylinder portion 20, a first flange 24 and a second flange 26 provided at both ends of the outer cylinder portion 22 in the center line CL direction, and a plurality of brake disk mounting portions 28 (see FIG. 6 etc.) protruding radially outward from the outer peripheral edge of the second flange 26 around the center line CL. Hereinafter, unless otherwise specified, the radial direction means the radial direction around the center line CL.

[0016] On the inner cylindrical portion 20, a flange portion 21 protruding radially outward from one end in the direction of the center line CL is formed. The outer peripheral edge of the flange portion 21 is fitted to the inner peripheral surface of the outer cylindrical portion 22 by press-fitting or the like. As a result, the inner cylindrical portion 20 and the outer cylindrical portion 22 rotate integrally about the center line CL.

[0017] The first flange 24 extends radially outward from one end in the direction of the center line CL of the outer cylindrical portion 22. Also, the second flange 26 extends radially outward from the other end in the direction of the center line CL of the outer cylindrical portion 22.

[0018] Next, the shape of the first flange 24 will be described with reference to FIGS. 3 to 5. As shown in FIGS. 3 to 5, the first flange 24 is formed in a disk shape having a predetermined thickness in the direction of the center line CL. Also, a reference surface 30 is formed on the side of the first flange 24 opposite to the second flange 26 in the direction of the center line CL and perpendicular to the center line CL. By notching the reference surface 30 in an annular shape, an annular space 32 having a predetermined depth in the direction of the center line CL is formed. In the present embodiment, the annular space 32 is formed by cutting the reference surface 30 using, for example, a milling cutter.

[0019] By forming the annular space 32 in the reference surface 30 of the first flange 24, a cylindrical boss portion 36 having a boss hole 34 through which the axle 12 is inserted is formed on the radially inner side of the first flange 24. Also, an annular peripheral wall 38 formed parallel or substantially parallel to the center line CL is formed on the radially outer side of the boss portion 36. Also, a bottom wall 39 having a plane perpendicular to the center line CL is formed between the boss portion 36 and the peripheral wall 38. Thereby, the annular space 32 is formed surrounded by the boss portion 36, the bottom wall 39, and the peripheral wall 38.

[0020] Further, as shown in FIG. 5, the connecting portion 41 that connects the inner peripheral surface 45 of the peripheral wall 38 and the bottom wall 39 is formed as a curved surface (arc-shaped curved surface) where the inner peripheral surface 45 and the bottom wall 39 are smoothly connected. Similarly, the connecting portion 48 that connects the bottom wall 39 and the outer peripheral surface of the boss portion 36 is formed as a curved surface (arc-shaped curved surface) where the bottom wall 39 and the outer peripheral surface of the boss portion 36 are smoothly connected.

[0021] A plurality of spoke mounting holes 40 to which the ends of the spokes 18 are fixed are formed on the inner peripheral surface 45 of the peripheral wall 38. The spokes 18 are fixed to the hub 14 at their ends while being inserted through the spoke mounting holes 40. The plurality of spoke mounting holes 40 are formed along the inner peripheral surface 45 of the peripheral wall 38 so as to be arranged in the circumferential direction. In FIGS. 3 to 5, the ends (heads 46) of the spokes 18 are shown fixed to the respective spoke mounting holes 40.

[0022] As shown in FIGS. 3 and 4, the inner peripheral surface 45 of the peripheral wall 38 is formed in a periodic wave shape. Specifically, the inner peripheral surface 45 is formed such that convex portions 42 protruding inward in the radial direction and concave portions 44 recessed outward in the radial direction are alternately arranged in the circumferential direction. As a result, the plurality of convex portions 42 are arranged at equal intervals in the circumferential direction of the peripheral wall 38. Similarly, the plurality of concave portions 44 are arranged at equal intervals in the circumferential direction of the peripheral wall 38.

[0023] The convex portions 42 and the concave portions 44 are formed by the inner peripheral surface 45 of the peripheral wall 38. Further, when viewed from the direction of the center line CL of the boss hole 34 (axial direction), the convex portions 42 and the concave portions 44 are each formed in an arc shape, and these are connected by a smooth curve. That is, the inner peripheral surface 45 forming the convex portions 42 and the concave portions 44 is formed as a circumferentially continuous curved surface.

[0024] Two spoke mounting holes 40 are formed in each of the convex portions 42. As a result, the two spoke mounting holes 40 are arranged at equal intervals in the circumferential direction on the inner peripheral surface 45 of the peripheral wall 38. The two spoke mounting holes 40 are at positions shifted in the direction of the center line CL and open in different directions from each other.

[0025] Each recess 44 is formed between the spoke mounting holes 40 adjacent in the circumferential direction on the inner peripheral surface 45 of the peripheral wall 38. Here, the adjacent spoke mounting holes 40 correspond to the spoke mounting holes 40 at the same position in the direction of the center line CL. Further, each recess 44 is formed so as to be recessed radially outward from the position where the spoke mounting hole 40 of the convex portion 42 is formed. The position where the spoke mounting hole 40 is formed corresponds to the position of a seating surface (not shown in FIGS. 3 to 5) formed around the spoke mounting hole 40. A hemispherical head 46 is integrally provided at the end of the spoke 18 on the side fixed to the hub 14. In a state where the end of the spoke 18 is fixed to the hub 14, a spoke-side seating surface (not shown) formed on the head 46 is in contact with the seating surface of the spoke mounting hole 40. At the time of assembly, the spoke 18 is inserted into the spoke mounting hole 40 from the inner peripheral surface 45 of the peripheral wall 38. Next, the spoke 18 is moved until the spoke-side seating surface of the spoke 18 comes into contact with the seating surface of the spoke mounting hole 40.

[0026] The seating surface of the spoke mounting hole 40 has exactly the same shape as the seating surface 66 of the spoke mounting hole 60 formed in the second flange 26 (see FIGS. 6 to 9). As shown in FIGS. 6 to 9, seating surfaces 66 that come into contact with the spoke-side seating surfaces of the hemispherical heads 46 of the spokes 18 are respectively formed around the spoke mounting holes 60.

[0027] Next, the shape of the second flange 26 will be described with reference to FIGS. 6 to 9. The second flange 26 extends radially outward from the other end of the outer cylindrical portion in the direction of the center line CL, and is formed in a disk shape having a predetermined thickness in the direction of the center line CL. Further, a reference surface 50 is formed on the side opposite to the first flange 24 in the direction of the center line CL and perpendicular to the center line CL. By notching the reference surface 50 in an annular shape, an annular space 52 having a predetermined depth in the direction of the center line CL is formed. In the present embodiment, the annular space 52 is formed, for example, by cutting the reference surface 50 using a milling cutter.

[0028] By forming an annular space 52 in the reference plane 50 of the second flange 26, a cylindrical boss portion 56 is formed on the radially inner side of the second flange 26, in which a boss hole 54 through which the axle 12 is inserted is formed. Further, on the radially outer side of the boss portion 56, an annular peripheral wall 58 is formed that is formed parallel or substantially parallel to the center line CL. Further, a bottom wall 59 having a plane perpendicular to the center line CL is formed between the boss portion 56 and the peripheral wall 58. As a result, the annular space 52 is formed surrounded by the boss portion 56, the bottom wall 59, and the peripheral wall 58.

[0029] Further, as shown in FIG. 9, the connecting portion 61 that connects the inner peripheral surface 65 of the peripheral wall 58 and the bottom wall 59 is formed as a curved surface (arc-shaped curved surface) where these inner peripheral surface 65 and bottom wall 59 are smoothly connected. Similarly, the connecting portion 68 that connects the bottom wall 59 and the inner peripheral surface of the boss portion 56 is formed as a curved surface (arc-shaped curved surface) where the bottom wall 59 and the inner peripheral surface of the boss portion 56 are smoothly connected.

[0030] A plurality of spoke mounting holes 60 to which the ends (heads 46) of the spokes 18 are fixed are formed in the inner peripheral surface 65 of the peripheral wall 58. The plurality of spoke mounting holes 60 are formed periodically in the circumferential direction on the inner peripheral surface 65 of the peripheral wall 58.

[0031] As shown in FIGS. 6 to 8, the inner peripheral surface 65 of the peripheral wall 58 is formed in a periodic wave shape. Specifically, the inner peripheral surface 65 is formed such that convex portions 62 protruding inward in the radial direction and concave portions 64 recessed outward in the radial direction are arranged alternately in the circumferential direction. As a result, the convex portions 62 are arranged at equal intervals in the circumferential direction of the peripheral wall 58. Similarly, the plurality of concave portions 64 are arranged at equal intervals in the circumferential direction of the peripheral wall 58.

[0032] The convex portions 62 and the concave portions 64 are formed by the inner peripheral surface 65 of the peripheral wall 58. Further, as shown in FIG. 8, when viewed from the direction of the center line CL of the boss hole 54 (when viewed along the center line CL direction), the convex portions 62 and the concave portions 64 are each formed in an arc shape, and these are connected by a smooth curve. That is, the inner peripheral surface 65 is formed as a circumferentially continuous curved surface.

[0033] Two spoke mounting holes 60 are formed at two locations on each convex portion 62. As a result, two spoke mounting holes 60 are arranged at equal intervals in the circumferential direction on the inner peripheral surface 65 of the peripheral wall 58. The two spoke mounting holes 60 are located at positions offset in the direction of the center line CL and open in different directions from each other.

[0034] Each concave portion 64 is formed between adjacent spoke mounting holes 60 in the circumferential direction on the inner peripheral surface 65 of the peripheral wall 58. Here, the adjacent spoke mounting holes 60 correspond to the spoke mounting holes 60 at the same position in the direction of the center line CL. In addition, each concave portion 64 is formed so as to be recessed radially outward from the position where the spoke mounting hole 60 is formed. The position where the spoke mounting hole 60 is formed corresponds to the position of a seat surface 66 formed around the spoke mounting hole 60. When attaching the spoke 18 to the spoke mounting hole 60, the spoke 18 is inserted into the spoke mounting hole 60 until the spoke-side seat surface of the hemispherical head 46 provided at the end of the spoke 18 on the hub 14 side abuts against the seat surface 66 formed around the spoke mounting hole 60.

[0035] [Function] As described above, between adjacent spoke mounting holes 40 on the inner peripheral surface 45 of the peripheral wall 38 of the first flange 24, a recess 44 that is recessed radially outward from the position (seat surface) of the spoke mounting hole 40 is formed. As a result, the thickness of the peripheral wall 38 is reduced and the flash of the peripheral wall 38 is reduced, so that the weight of the hub 14 is reduced. Further, the recess 44 is formed of a smooth curved surface and is connected to the adjacent convex portion 42 and the bottom wall 39 by smooth curved surfaces, so that the occurrence of stress concentration is suppressed and a decrease in the strength of the hub 14 is suppressed. Similarly, on the inner peripheral surface 65 of the peripheral wall 58 of the second flange 26, a recess 64 that is recessed radially outward from the position (seat surface 66) of the spoke mounting hole 60 is formed. As a result, the thickness of the peripheral wall 58 is reduced and the flash of the peripheral wall 58 is reduced, so that the weight of the hub 14 is reduced. Further, the recess 64 is formed of a smooth curved surface and is connected to the adjacent convex portion 62 and the bottom wall 59 by smooth curved surfaces, so that the occurrence of stress concentration is suppressed and a decrease in the strength of the hub 14 is suppressed. Therefore, it is possible to realize the hub 14 that can suppress an increase in weight while suppressing a decrease in the strength of the hub 14.

[0036] [Embodiment 2] Next, another aspect of the wheel 10 to which the present invention is applied will be described. FIG. 10 is a perspective view of a hub 100 corresponding to another aspect of the present invention. FIG. 11 is a perspective view of the hub 100 viewed from an angle different from that in FIG. 10. FIG. 12 is a view of the hub 100 viewed from one side in the direction of the center line CL. FIG. 13 is a cross-sectional view of the hub 100 cut along the cutting line C in FIG. 12. In FIGS. 10 to 13, views in which only the shape of the annular space 114 formed in the second flange 106 described later is drawn in solid lines are shown as reference views in FIGS. 18 to 21, respectively.

[0037] As shown in FIGS. 10 to 13, the hub 100 includes a cylindrical tubular portion 102, a first flange 104 and a second flange 106 provided at both ends in the direction of the center line CL, and a plurality of brake disk mounting portions 110 that project radially outward from the outer peripheral edge of the second flange 106.

[0038] The first flange 104 extends radially outward from one end of the cylindrical portion 102 in the direction of the center line CL. The second flange 106 extends radially outward from the other end of the cylindrical portion 102 in the direction of the center line CL.

[0039] As shown in FIGS. 10 to 13, the second flange 106 is formed in a disk shape having a predetermined thickness in the direction of the center line CL. Further, on the side opposite to the first flange 104 in the direction of the center line CL of the second flange 106, a reference plane 112 formed perpendicular to the center line CL is formed. By annularly notching the reference plane 112, an annular space 114 having a predetermined depth in the direction of the center line CL is formed. In the present embodiment, the annular space 114 is formed by cutting the reference plane 112 using, for example, a milling cutter.

[0040] By forming the annular space 114 in the reference plane 112 of the second flange 106, a cylindrical boss portion 118 in which a boss hole 116 through which the axle 12 is inserted is formed is formed on the radially inner side of the second flange 106. Further, on the radially outer side of the boss portion 118, an annular peripheral wall 120 formed parallel or substantially parallel to the center line CL is formed. Further, a bottom wall 122 having a plane perpendicular to the center line CL is formed between the boss portion 118 and the peripheral wall 120. Thereby, the annular space 114 is formed surrounded by the boss portion 118, the bottom wall 122, and the peripheral wall 120.

[0041] Further, as shown in FIG. 13, the connecting portion 124 connecting the inner peripheral surface 125 of the peripheral wall 120 and the bottom wall 122 is formed into a curved surface (arc-shaped curved surface) in which these inner peripheral surface 125 and bottom wall 122 are smoothly connected. Similarly, the connecting portion 132 connecting the bottom wall 122 and the outer peripheral surface of the boss portion 118 is formed into a curved surface (arc-shaped curved surface) in which these bottom wall 122 and the outer peripheral surface of the boss portion 118 are smoothly connected.

[0042] On the inner peripheral surface 125 of the peripheral wall 120, a plurality of spoke mounting holes 126 to which the ends of the spokes 18 are fixed are formed. The spoke mounting holes 126 are formed in a plurality in the circumferential direction along the inner peripheral surface 125 of the peripheral wall 120. Around each spoke mounting hole 126, a seating surface 127 that abuts against the spoke-side seating surface of the head 46 of the spoke 18 is formed.

[0043] As shown in FIGS. 10 to 12, the inner peripheral surface 125 of the peripheral wall 120 is formed in a periodic wave shape. Specifically, the inner peripheral surface 125 is formed such that convex portions 128 protruding inward in the radial direction and concave portions 130 protruding outward in the radial direction are alternately arranged in the circumferential direction. As a result, the plurality of convex portions 128 are arranged at equal intervals in the circumferential direction of the peripheral wall 120. Similarly, the plurality of concave portions 130 are arranged at equal intervals in the circumferential direction of the peripheral wall 120.

[0044] The convex portions 128 and the concave portions 130 are formed from the inner peripheral surface 125 of the peripheral wall 120. Also, the convex portions 128 and the concave portions 130 are both formed in a trapezoidal shape when viewed from the direction of the center line CL of the boss hole 116. The corner portions of the trapezoidal shapes of the convex portions 128 and the concave portions 130 are all formed as smooth curved surfaces. That is, the inner peripheral surface 125 formed by the convex portions 128 and the concave portions 130 is formed as a continuously curved surface in the circumferential direction.

[0045] Each concave portion 130 is formed between adjacent spoke mounting holes 126 on the inner peripheral surface 125 of the peripheral wall 120. Also, the concave portion 130 is recessed radially outward from the position (seating surface 127) of the spoke mounting hole 126.

[0046] Also, although the description of the first flange 104 is omitted, when the first flange 104 is viewed from the direction of the center line CL, convex portions and concave portions formed in a trapezoidal shape similar to the second flange 106 are alternately arranged in the circumferential direction.

[0047] As described above, the recess 130 formed on the inner peripheral surface 125 of the peripheral wall 120 may be formed in a trapezoidal shape in which the corners are formed into smooth curved surfaces when viewed from the direction of the center line CL. Even when the recess 130 is formed in a trapezoidal shape, the stress concentration is suppressed by forming the recess 130 as a whole from a smooth curved surface, and the weight of the hub 100 can be reduced.

[0048] [Modification Example] Also, in the above-described embodiment, the recesses 44, 64, and 130 were formed between the spoke mounting holes 40, 60, and 126 adjacent to each other in the circumferential direction. However, it is not necessary to form recesses at all sites between the spoke mounting holes 40, 60, and 126 adjacent to each other in the circumferential direction. For example, between the spoke mounting holes adjacent to each other in the circumferential direction, portions where recesses are formed and portions where recesses are not formed may be alternately arranged.

[0049] Also, in the above-described embodiment, when viewed from the direction of the center line CL, the convex portions and the recesses were each formed in an arc shape or a trapezoidal shape. However, the convex portions and the recesses do not necessarily have to have the same shape. For example, while the convex portion is formed in a trapezoidal shape, the recess may be formed in an arc shape.

[0050] Also, in the above-described embodiment, it was assumed that the annular space 32 was formed by cutting the reference surface 30 with a milling cutter or the like. However, the hub 14 may be manufactured by casting, and the annular space 32 may be formed during casting.

[0051] Also, in the above-described embodiment, the recesses 44 and 64 were formed on both sides of the first flange 24 and the second flange 26. However, the recesses 44 and 64 may be formed on one of the first flange 24 and the second flange 26.

[0052] Also, in the above-described embodiment, the recesses 44 and 64 were formed in an arc shape when viewed from the direction of the center line CL, and the recess 130 was formed in a trapezoidal shape when viewed from the direction of the center line CL. However, the shape of the recess is not necessarily limited to an arc and a trapezoid. That is, any shape that is recessed radially outward from the seat surface of the spoke mounting hole may be used.

Description of Reference Numerals

[0053] 12: Axle 14, 100: Hub 18: Spoke 34, 54, 116: Boss hole 36, 56, 118: Boss part 38, 58, 120: Peripheral wall 40, 60, 126: Spoke mounting hole 44, 64, 130: Concave part 45, 65, 125: Inner peripheral surface

Claims

1. a boss portion having a boss hole through which an axle is inserted; a peripheral wall formed on the radially outer side of the boss portion; a plurality of spoke mounting holes formed on the inner peripheral surface of the peripheral wall so as to be arranged in the circumferential direction and to which the ends of the spokes are fixed; a hub for a spoke wheel, comprising a recess formed between at least some adjacent spoke mounting holes on the inner peripheral surface of the peripheral wall and recessed radially outward from the position of the spoke mounting holes.

2. The hub for a spoke wheel according to claim 1, wherein the recess is formed in an arc shape when viewed from the direction of the center line of the boss hole.

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