TWM446151U - A bicycle crank arm - Google Patents

Description

Crank arm for bicycle

The present invention relates to a crank arm, and more particularly to a crank arm for a bicycle that can be coupled to a crankshaft.

In the crank shaft for bicycles, a crank arm is incorporated. Conventionally, a technique for changing the distance from the crankshaft to the pedal in the crank arm has been known (for example, refer to the specification of U.S. Patent No. 7,017,444). The conventional crank arm has a crankshaft coupling portion, the arm body is provided to be movable in and out of the crankshaft coupling portion, and the pedal engagement portion is provided on the arm body to be movable in the longitudinal direction. The arm body can be fixed at a plurality of positions in the longitudinal direction at the crank shaft joint portion. The pedal joint portion can be fixed at a plurality of positions in the longitudinal direction at the arm body. Thereby, the distance between the crankshaft and the pedal can be changed.

In the conventional crank arm, the distance between the crank shaft and the pedal is changed between the arm body and the crank shaft coupling portion and between the arm body and the pedal coupling portion. Thereby, the distance between the crankshaft and the pedal is changed in the intermediate portion in the longitudinal direction of the crank arm. In such a conventional crank arm, since a complicated structure is disposed in the longitudinal direction intermediate portion of the crank arm, it is difficult to ensure sufficient rigidity of the intermediate portion in the longitudinal direction of the crank arm.

The object of the present invention is to provide a structure in which the rigidity of the intermediate portion in the longitudinal direction of the crank arm can be easily ensured in the crank arm in which the distance between the pedal and the crankshaft can be changed.

The crank arm for a bicycle relating to the present invention is a crank arm for a bicycle that can be coupled to a crankshaft. A crank arm for a bicycle has an arm body extending in a long direction and a crank shaft joint. The crankshaft coupling portion is a plurality of positions of the arm body in the long direction, and is coupled to the crankshaft to transmit torque.

In this crank arm, for example, a pedal is provided at one end of the arm body. Further, on the other end side of the arm main body, any one of a plurality of positions in the longitudinal direction is coupled to the arm main body by a crank shaft coupling portion coupled to the crank shaft. Here, at the other end side of the crank arm, any one of the plurality of positions in the longitudinal direction of the crank shaft joint portion is connected to the arm body, so that the long direction of the crank arm that requires sufficient rigidity can be obtained without arranging a complicated structure. The middle portion is made into a simple shape. Thereby, it is possible to easily ensure sufficient rigidity of the intermediate portion in the longitudinal direction of the crank arm.

The crankshaft coupling portion has a long hole extending in the longitudinal direction, and the long hole has a pair of opposing faces, and at least one of the pair of opposing faces may have a plurality of pin groove engaging portions which are spaced apart at intervals in the longitudinal direction. The configuration can be engaged with the crankshaft. In this case, the moment is reliably transmitted by the pin groove engagement portion.

The crankshaft coupling portion may include a pressed surface, a shaft member, a pressing member, and a fastening member. The pressed surface is disposed on at least one of the two sides of the long hole, and the first inclined portion is formed to be located from the first surface located on the inner side in the axial direction in a state of being attached to the crankshaft. The second surface on the outer side in the axial direction is tapered to be tapered. The shaft member has a male spiral portion and a female spiral portion screwed to the crank shaft. The pressing member is faced to face the first inclined portion that is disposed to contact the pressed surface, and has a second inclined portion that is inclined in a direction opposite to the first inclined portion. The fastening member moves the pressing member in the axial direction in a direction in which the axial direction approaches at least the crankshaft.

Here, by fastening the member, the pressing member is on the side close to the crankshaft When moving, the pressing member presses the pressed surface in the radial direction by the relative movement of the first inclined portion and the second inclined portion in the axial direction. Thereby, the crankshaft joint is tightly and strongly bonded to the crankshaft.

According to the present invention, at the other end side of the crank arm, any one of the plurality of positions in the longitudinal direction of the crank shaft joint portion is coupled to the arm body. Therefore, the long-direction intermediate portion of the crank arm that requires sufficient rigidity can be made into a simple shape without having to arrange a complicated structure. Thereby, it is possible to easily ensure sufficient rigidity of the intermediate portion in the longitudinal direction of the crank arm.

<Structure of crank assembly>

The crank assembly 10 according to the embodiment of the present invention is attached to a tubular hanging portion 8 provided in a bicycle frame. The crank assembly 10 has a crank shaft 12, a through suspension portion 8, a bearing unit 14, a first positioning member 16 and a second positioning member 18, a pair of crank arms 20a, 20b according to an embodiment of the present invention, and a sprocket 22 . The bearing unit 14 is provided to support the crankshaft 12 to be freely rotatable in the suspension portion 8. The first positioning member 16 and the second positioning member 18 are provided for positioning and fixing the bearing unit 14 at the hanging portion 8.

The crankshaft 12 has a through hole 12a inside. At both ends of the through hole 12a, a first female spiral portion 12b and a second female spiral portion 12c are formed. The first female helix portion 12b on the right side of the first figure is the female helix portion of the right screw, and the second female helix portion 12c on the left side of the first figure is the female helix portion of the left screw. At both ends of the crankshaft 12, a first crank arm joint portion 12d and a second crank arm joint portion 12e for coupling to the crank arms 20a, 20b are provided. The first crank arm joint portion 12d and the second crank arm joint portion 12e, as shown in the fourth figure, have a pair of bolt slots arranged in parallel with each other From 12f. The pair of pin groove projections 12f have a plurality of projections 12g formed at intervals along the longitudinal direction of the crank arms 20a. At the first crank arm joint portion 12d, the sprocket 22 is coupled to be integrally rotatable. The sprocket 22 is disposed between the arm body 30 and the step of the crankshaft 12.

Therefore, in this embodiment, the axial length of the first crank arm joint portion 12d is longer than the thickness of the sprocket 22 by the second crank arm joint portion 12e. However, the first crank arm joint portion 12d and the second crank arm joint portion 12e may be the same length in the axial direction.

The bearing unit 14, as shown in the first figure, has a cylindrical outer wheel 14a, which is positioned by the first positioning member 16 and the second positioning member 18, and a pair of a plurality of rotating wheels 14b spaced apart in the circumferential direction. It is disposed between the inner peripheral surface of both end portions of the outer ring 14a and the crankshaft 12.

The first positioning member 16 is a tubular member screwed to the inner peripheral surface on the right side of the first figure of the suspension portion 8, and is capable of contacting the right end surface of the outer ring 14a. The second positioning member 18 is a tubular member screwed to the inner peripheral surface of the left side of the first figure of the suspension portion 8, and is capable of contacting the left end surface of the outer ring 14a.

<Structure of crank arm>

The crank arm 20a coupled to the first crank arm joint portion 12d, as shown in the second to fifth figures, includes: an arm body 30 extending in the longitudinal direction; and a crank shaft coupling portion 32 at the base of the arm body 30 On the end side, the crankshaft 12 can be coupled to any of a plurality of positions in the longitudinal direction. The arm body 30 is a rod-shaped member that extends in the longitudinal direction. At the front end portion of the arm body 30, a pedal joint portion 30a is provided in the form of a female screw, and the pedal joint portion 30a can be coupled to the pedal PD (refer to Fig. 5).

The crankshaft coupling portion 32 is provided to closely connect the crankshaft 12 to a plurality of positions in the longitudinal direction of the arm body 30. The crankshaft coupling portion 32 is a plurality of positions at the shortest position indicated by the two-dot chain line in the third figure and the shortest position indicated by the one-dotted line. Between the crankshafts 12 can be combined. Thereby, the distance L from the crankshaft 12 to the pedal PD can be set in plural stages. The crankshaft coupling portion 32 includes an elongated hole 40, a pressed surface 42, a shaft member 44, a pressing member 46, and a fastening member 48. The long hole 40 is formed on the proximal end side of the arm body 30 and extends in the longitudinal direction.

The elongated hole 40 has a pair of opposing faces 40a, 40b. At least one of the pair of opposing faces 40a and 40b has a plurality of pin groove engaging portions 40c that are engageable with the projections 12g of the pin groove projections 12f of the crankshaft 12 at intervals in the longitudinal direction. In this embodiment, the pin groove engaging portion 40c is provided on both opposing faces 40a and 40b.

The pressed surface 42 is disposed on at least one of both sides of the elongated hole 40 of the arm body 30 as shown in the second figure. In this embodiment, a pair of two sides of the long hole 40 disposed in the arm body 30 are provided. The pair of pressed surface 42 has a pair of first inclined portions 42a, and the first surface 30b located on the inner side in the axial direction of the arm main body 30 is oriented in the axial direction in a state where the crank arm 20a is attached to the crankshaft 12. The outer second surface 30c is formed to be tapered gradually.

As shown in the second figure, the shaft member 44 has a male screw portion 44a, a first female screw portion 12b screwed to the crank shaft 12 formed at the front end portion, and a pair of coupling surfaces 44b which are arranged in parallel. The fastening member 48 formed at the base end portion is joined. The first coupling hole 44c is formed in the pair of coupling faces 44b, and the first coupling hole 44c allows the coupling pin 50 of the fastening member 48 to pass therethrough.

The pressing member 46 is moved to the left in the second drawing by the fastening member 48, and the pin groove engaging portion 40c is pressed toward the protruding portion 12g of the crank shaft 12, that is, toward the inner side in the radial direction of the second drawing. The pressing member 46 is formed in a C shape, and has a pair of opposing portions 46a facing the pair of pressed faces 42 and a connecting portion 46b for connecting the pair of opposing portions 46a to the arm. The outside of the body 30. The pair of opposing portions 46a are opposed to each other so as to contact the first inclined portion 42a of the pressed surface 42. The pair of opposing portions 46a have a pair of second inclined portions 46c on the inner side in the radial direction, and the pair of second inclined portions 46c are inclined in the opposite direction to the first inclined portion 42a. The joint portion 46b has a through hole 46d through which the shaft member 44 can pass. The inner diameter of the hole 46d is preferably smaller than the outer diameter of the male spiral portion 44a. Thereby, the pressing member 46 does not fall off from the shaft member 44 that connects the fastening members 48.

The fastening member 48 moves the pressing member 46 in a direction approaching at least the crankshaft 12 in the axial direction of the shaft member 44. The fastening member 48 is coupled by the coupling pin 50 so as to be rockable on the shaft member 44. The fastening member 48, as shown in Fig. 5, has a base end portion 48a that is coupled to be rotatable about the shaft member 44, and an operating portion 48b that rotates the base end portion 48a relative to the shaft member 44.

The base end portion 48a is divided into two joint portions 44b that sandwich the shaft member 44. The base end portion 48a has a cam surface 48c that moves the pressing member 46 in a direction approaching at least the crankshaft 12 in the axial direction in response to the rotation of the base end portion 48a by the operation portion 48b. The cam surface 48c is formed such that the distance from the center of the joint pin 50 gradually increases. In this embodiment, the cam surface 48c is constituted by an arcuate surface centered at a position separated from the center of the joint pin 50. The cam surface 48c contacts the outer side in the axial direction of the coupling portion 46b of the pressing member 46, and moves the pressing member 46 in the axial direction in the direction close to the crankshaft 12. Further, the proximal end portion 48a has a pair of second coupling holes 48d through which the coupling pin 50 can pass. The second coupling hole 48d and the coupling pin 50 can be coupled by a clearance fit. The second connecting holes 48d are concentrically arranged on both sides of the first connecting hole 44c.

The coupling pin 50 is fixed to the base end portion 48a by a suitable fixing means such as caulking fixing, subsequent fixing, and press-fitting in the second coupling hole 48d.

The operation portion 48b is a rod-shaped member that extends from the proximal end portion 48a in the radial direction of the shaft member 44. The operation portion 48b is provided such that the fastening member 48 is rocked by hand to a pressing position indicated by a solid line in the fifth drawing and a pressing release position indicated by a two-dot chain line in the fifth drawing. At the pressing position, the cam surface 48c of the proximal end portion 48a is disposed at the position farthest from the center of the coupling pin 50. Further, at the pressing release position, the cam surface 48c of the proximal end portion 48a is disposed at a position closest to the center of the coupling pin 50.

The crank arm 20b to which the second crank arm coupling portion 12e of the crankshaft 12 is coupled is different from the crank arm 20a in that the male screw portion 44a of the shaft member 44 is a left screw. Since the other points are the same as the crank arm 20a, the description is omitted.

<Order change order of crankshaft>

In the bicycle crank arm 20a of the present invention thus constructed, the position of the crank shaft coupling portion 32 of the arm body 30 is changed, and the operating portion 48b of the fastening member 48 is lifted by hand to fasten the fastening member 48. Shake to the release position. When the fastening member 48 is at the pressing release position, the fastening by the fastening member 48 is released, and the pressing of the pressed surface 42 of the pressing member 46 is released.

In this state, the fastening member 48 is rotated counterclockwise in the third figure to detach the shaft member 44 from the crankshaft 12. Then, the pressing member 46 is separated from the shaft member 44. Next, the arm body 30 is separated from the crank shaft 12, and the bolt groove engaging portion 40c is engaged with the projection portion 12g at a desired position, and the arm body 30 is attached to the crank shaft 12 again. When the arm body 30 is mounted to the crankshaft 12, the fastening member 48 is held to screw the shaft member 44 into the crankshaft 12 to a specific position. Then, the operation portion 48b of the fastening member 48 is held, and the fastening member 48 is swung from the pressing release position to the pressing position. Thereby, the cam surface 48c of the fastening member 48 moves the pressing member 46 in the direction of the crankshaft 12 in the axial direction toward the projection. The portion 12g presses the pin groove engaging portion 40c, and the arm body 30 is tightly coupled to the crank shaft 12.

Here, the crank shaft coupling portion 32 is connected to any of the plurality of positions in the longitudinal direction on the other end side of the crank arm 20a on the side opposite to the one end side of the crank arm 20 forming the pedal coupling portion 30a. On the arm body 30. Therefore, the long-direction intermediate portion of the crank arm 20a requiring sufficient rigidity can be made into a simple shape without having to arrange a complicated structure. Thereby, it is possible to easily ensure sufficient rigidity of the intermediate portion in the longitudinal direction of the crank arm 20a.

Further, when the pressing member 46 moves in the direction of approaching the crankshaft 12 by the fastening member 48, the pressing member 46 is pressed in the radial direction by the relative movement of the first inclined portion 42a and the second inclined portion 46c in the axial direction. The face 42 is pressed. Thereby, the crankshaft coupling portion 32 is tightly coupled to the crankshaft 12.

<Other Embodiments>

In the above, an embodiment of the present invention has been described, but the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the invention. In particular, the plurality of embodiments and modifications described in the present specification can be arbitrarily combined as needed.

(a) In the above embodiment, the length of the crank arm 20a is changed. Although it is necessary to separate the crank arm 20a from the crankshaft 12, the present invention is not limited thereto. For example, the pin groove engaging portion of the long hole is tapered, and the long hole is formed such that the central portion is wider than the both end portions. When pressed by the pressing member, the pin groove engaging portion is engaged with the crank shaft, and when the pressing is released, the long hole can be engaged. The pin groove engaging portion is disengaged by elasticity. Thereby, the crank arm 20a is not separated from the crankshaft 12, and the length of the crank arm 20a can be changed.

(b) in the above embodiment, the shaft is made by the fastening member 48 The parts rotate, but this creation is not limited to this. For example, as shown in the sixth figure, the crank shaft 112 is provided with a male screw portion 144, and the pressing member 46 can be brought close to the crank in the axial direction by the fastening member 148 which is screwed to the nut portion of the male screw portion 144. The direction of the shaft 12 moves.

(c) In the above embodiment, the fastening member 48 is provided. However, the fastening member may not be provided, and the shaft member may be a hexagonal bolt or a hexagon bolt.

(d) In the above embodiment, the male screw portion 44a is provided on the shaft member 44, and the shaft member 44 is fixed to be detachable from the crankshaft. However, the fixing structure of the detachable shaft member is not limited thereto. For example, the shaft member may be fixed to be detachable from the crankshaft by a known fixing structure other than screw engagement.

8‧‧‧ hanging section

10‧‧‧ crank assembly

12, 112‧‧‧ crankshaft

12a‧‧‧through holes

12b‧‧‧First female spiral

12c‧‧‧Second female spiral

12d‧‧‧First crank arm joint

12e‧‧‧Second crank arm joint

12f‧‧‧Tie groove protrusion

12g‧‧‧protrusion

14‧‧‧ bearing unit

14a‧‧‧Cylindrical outer wheel

14b‧‧‧Rotating wheel

16‧‧‧First positioning unit

18‧‧‧Second positioning unit

20a, 20b‧‧‧ crank arms

22‧‧‧Sprocket

30‧‧‧arm body

30a‧‧‧ pedal joint

30b‧‧‧ first side

30c‧‧‧ second side

32‧‧‧ crank shaft joint

40‧‧‧ long hole

40a, 40b‧‧‧ opposite

40c‧‧‧Bolt groove

42‧‧‧ pressed face

42a‧‧‧First inclined part

44‧‧‧Axis parts

44a, 144‧‧ ‧ male spiral

44b‧‧‧ link

44c‧‧‧First Link Hole

46‧‧‧Resist parts

46a‧‧‧ opposite

46b‧‧‧Connecting Department

46c‧‧‧Second inclined part

46d‧‧‧through hole

48, 148‧‧‧ fastening parts

48a‧‧‧ base end

48b‧‧‧Operation Department

48c‧‧‧ cam surface

48d‧‧‧Second connection hole

50‧‧‧Links

L‧‧‧ distance

PD‧‧‧ pedal

First Fig.: A cross-sectional view of a crank assembly having a crank arm according to an embodiment of the present invention.

Second figure: An enlarged view of the section II of the first figure.

Third picture: Front view of the crank arm.

Figure 4: Sectional view of the cutting line IV-IV of the second figure.

Figure 5: Plan view of the crank arm.

Fig. 6 is a cross-sectional enlarged view of the second embodiment.

12‧‧‧ crankshaft

20a‧‧‧ crank arm

30‧‧‧arm body

30a‧‧‧ pedal joint

32‧‧‧ crank shaft joint

40‧‧‧ long hole

40a, 40b‧‧‧ opposite

40c‧‧‧Bolt groove

42‧‧‧ pressed face

42a‧‧‧First inclined part

44‧‧‧Axis parts

44c‧‧‧First Link Hole

44b‧‧‧ link

48‧‧‧ fastening parts

46‧‧‧Resist parts

48b‧‧‧Operation Department

48a‧‧‧ base end

L‧‧‧ distance

50‧‧‧Links

Claims (7)

A crank arm for a bicycle, which can be coupled with a crank shaft, and includes: an arm body extending in a long direction; and a crank shaft joint portion coupled to the crank shaft at a plurality of positions of the arm body in the long direction Communicate the torque. The crank arm for a bicycle according to claim 1, wherein the crank shaft joint portion has a long hole extending in the longitudinal direction. The crank arm for a bicycle according to claim 2, wherein the long hole has a pair of opposing faces, and at least one of the opposing faces of the pair has a plurality of pin groove engaging portions, The long-distance spacing is configured to engage the aforementioned crankshaft. The crank arm for a bicycle according to claim 3, wherein the opposite faces of the pair of the pair have the aforementioned bolt groove engaging portion. The crank arm for a bicycle according to the second or third aspect of the invention, wherein the crankshaft coupling portion includes: a pressed surface disposed on at least one of the two sides of the long hole, having: first The inclined portion is formed to be gradually tapered from the first surface located on the inner side in the axial direction toward the second surface located on the outer side in the axial direction in a state of being attached to the crankshaft; the shaft member has a male spiral portion a female spiral portion screwed to the crank shaft; a pressing member facing the first inclined portion that is disposed to contact the pressed surface, and having a second inclined portion that is inclined in a direction opposite to the first inclined portion; The fastening member is coupled to the shaft member to make the front in the axial direction The pressing member moves in a direction close to at least the crankshaft, and when the pressing member moves in a direction close to the crankshaft in the axial direction by the fastening member, the first inclined portion and the second inclined portion are on the shaft The relative movement of the direction causes the pressing member to press the pressed surface in the radial direction. The crank arm for a bicycle according to claim 5, wherein the fastening member further includes: a base end portion coupled to be rotatable with the shaft member; and an operating portion to make the base end portion opposite Rotating in the aforementioned shaft member. The crank arm for a bicycle according to claim 6, wherein the base end portion has a cam surface corresponding to the rotation of the base end portion due to the operation portion, and the pressing member is in the axial direction. Moving in a direction approaching at least the aforementioned crankshaft.