Power transmission device for bicycle

Abstract

To provide a power transmission device for a bicycle which is suitable for a user.SOLUTION: A power transmission device 100 for a bicycle includes a first rotor 2, a pair of second rotors 3, an elastic member 4, and a stopper member 5. The pair of second rotors 3 are arranged so as to sandwich the first rotor 2 in an axial direction. The pair of second rotors 3 are removably mounted. The elastic member 4 elastically connects the first rotor 2 and the pair of second rotors 3. The stopper member 5 is arranged between the pair of second rotors 3. The first rotor 2 has opposite stopper surfaces.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a bicycle power transmission device. [Background technology]

[0002] A bicycle power transmission device that is configured to widen the torsion angle between the input plate and the output plate has been disclosed. For example, in the power transmission device disclosed in Patent Document 1, a pair of output plates are arranged to sandwich the input plate in the axial direction. An elastic member elastically connects the first input plate and the pair of second output plates. In addition, a fixing pin that connects the pair of output plates abuts against an end of a stopper hole, thereby restricting the relative rotation between the input plate and the output plate within a predetermined angle range. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-059347 A Summary of the Invention [Problem to be solved by the invention]

[0004] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a bicycle power transmission device that is suitable for the user. [Means for solving the problem]

[0005] A bicycle power transmission device according to a first aspect includes a first rotating body, a pair of second rotating bodies, an elastic member, and a stopper member. The first rotating body is rotatably arranged. The pair of second rotating bodies are arranged to sandwich the first rotating body in the axial direction. The pair of second rotating bodies are removably attached to each other. The elastic member elastically connects the first rotating body and the pair of second rotating bodies. The stopper member is arranged between the pair of second rotating bodies. The first rotating body has a stopper surface that faces the stopper member with a gap in between in the rotational direction.

[0006] With this configuration, the user can detach the pair of second rotating bodies from each other and replace them with, for example, a preferred stopper member or a preferred elastic member, thereby providing a bicycle power transmission device that is suited to the user.

[0007] A bicycle power transmission device according to a second aspect is the bicycle power transmission device according to the first aspect, further comprising a plurality of bolts. Each bolt is configured to removably attach the pair of second rotating bodies to each other. The stopper member has a through hole that passes through in the axial direction. The bolts extend through the through holes.

[0008] A bicycle power transmission device according to a third aspect is the bicycle power transmission device according to the first or second aspect, further comprising a sprocket part and a crank arm. The sprocket part is attached to one of the pair of second rotating bodies. The crank arm is configured to rotate integrally with the first rotating body.

[0009] A bicycle power transmission device according to a fourth aspect is the bicycle power transmission device according to the third aspect, and is configured as follows: The first rotating body has a hub portion, an outer flange portion, and an inner flange portion. The hub portion extends in the axial direction. The hub portion is cylindrical. The outer flange portion extends radially outward from the hub portion. The inner flange portion extends radially inward from the hub portion. The crank arm is attached to the inner flange portion.

[0010] A bicycle power transmission device according to a fifth aspect is the bicycle power transmission device according to the fourth aspect, and is configured as follows: The crank arm is spline-fitted into the inner flange portion.

[0011] A bicycle power transmission device according to a sixth aspect is the bicycle power transmission device according to the fourth or fifth aspect, and is configured as follows: The crank arm has an arm body portion and an attachment portion. The arm body portion extends radially. The attachment portion extends axially from an end of the arm body portion. The attachment portion passes through the inner flange portion. The attachment portion is fixed to the inner flange portion by crimping at its tip portion.

[0012] A bicycle power transmission device according to a seventh aspect is a bicycle power transmission device according to any one of the first to sixth aspects, and is configured as follows: The stopper member is selected from a plurality of types of stopper members having different circumferential sizes. Effect of the Invention

[0013] According to the present invention, a bicycle power transmission device suitable for the user can be provided. [Brief description of the drawings]

[0014] [Figure 1] FIG. [Diagram 2] FIG. [Diagram 3] FIG. 11 is a cross-sectional view of a power transmission device according to a modified example. [Figure 4] FIG. 13 is a front view of a power transmission device according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, a bicycle power transmission device (hereinafter simply referred to as a power transmission device) according to this embodiment will be described with reference to the drawings. In the following description, the axial direction is the direction in which the rotation axis O of the power transmission device extends. The circumferential direction is the circumferential direction of a circle centered on the rotation axis O, and the radial direction is the radial direction of a circle centered on the rotation axis O. The rotation direction is the direction in which the power transmission device rotates when the bicycle is traveling.

[0016] Fig. 1 is a cross-sectional view of a power transmission device. As shown in Fig. 1, the power transmission device 100 has a first rotating body 2, a pair of second rotating bodies 3, a plurality of elastic members 4, a plurality of stopper members 5, a sprocket portion 6, a crank arm 7, a plurality of bolts 8a, and nuts 8b. The power transmission device 100 is disposed rotatably about a rotation axis O.

[0017] The power transmission device 100 is mounted on a bicycle. The power transmission device 100 is mounted on, for example, a bicycle that is driven only by human power and does not have an electric motor or the like. The power transmission device 100 may also be mounted on a bicycle that has an electric motor. In this case, for example, the bicycle may have an electric mode in which it is driven only by the electric motor, and a human-powered mode in which it is driven only by human power. The bicycle may have an assist mode in which it is driven by both the electric motor and human power, or it may not have an assist mode. The power transmission device 100 is configured to transmit torque input to a pedal (not shown) attached to the tip of the crank arm 7 to a drive wheel (not shown).

[0018] 2 is a front view of the power transmission device 100 with some elastic members 4, the crank arm 7, and one of the pair of second rotating bodies 3 removed. As shown in Fig. 2, the power transmission device 100 is configured to rotate in a rotational direction R (clockwise in Fig. 2).

[0019] <First rotating body> As shown in Figs. 1 and 2, the first rotor 2 has a plurality of first housing portions 21. In this embodiment, the first rotor 2 has three first housing portions 21. Each of the first housing portions 21 penetrates in the axial direction. Each of the first housing portions 21 is disposed at intervals in the circumferential direction. Each of the first housing portions 21 is disposed at equal intervals.

[0020] The first rotating body 2 is disposed so as to be rotatable in a rotational direction R. Torque is input to the first rotating body 2 from the crank arm . The first rotating body 2 is configured to rotate integrally with the crank arm .

[0021] The first rotating body 2 has a hub portion 22, an outer flange portion 23, and an inner flange portion 24. The hub portion 22 is cylindrical and extends in the axial direction. When the power transmission device 100 is mounted on a bicycle, a crankshaft (not shown) extends through the hub portion 22.

[0022] The outer flange portion 23 extends radially outward from the hub portion 22. The first accommodating portion 21 is formed in this outer flange portion 23. The outer flange portion 23 is formed in the center of the hub portion 22 in the axial direction.

[0023] The inner flange portion 24 extends radially inward from the hub portion 22. The inner flange portion 24 has spline holes 241 on its inner circumferential surface. The inner flange portion 24 is formed at the axial end portion of the hub portion 22. The position at which the inner flange portion 24 is disposed is different in the axial direction from the position at which the outer flange portion 23 is disposed. In other words, the inner flange portion 24 does not overlap the outer flange portion 23 when viewed in the radial direction.

[0024] The first rotating body 2 has a plurality of stopper surfaces 25. More specifically, the first rotating body 2 has a plurality of cutout portions 26. The cutout portions 26 are arranged at intervals in the circumferential direction. The cutout portions 26 are arranged between the pair of first housing portions 21 in the circumferential direction. The cutout portions 26 open toward the outside in the radial direction. Of the inner wall surfaces that define the cutout portions 26, the surfaces that face the rotation direction R become the stopper surfaces 25.

[0025] The stopper surface 25 faces the rotation direction R. The stopper surface 25 faces the stopper member 5 with a gap therebetween in the rotation direction.

[0026] The first rotating body 2 can be made of, for example, iron, stainless steel, carbon fiber reinforced plastic (CFRP), or the like.

[0027] <Second rotating body> The pair of second rotating bodies 3 are arranged to be rotatable in a rotation direction R. The pair of second rotating bodies 3 are arranged to be rotatable relative to the first rotating body 2.

[0028] Since the pair of second rotating bodies 3 have substantially the same configuration, one of the second rotating bodies 3 will be described below, and a detailed description of the other second rotating body 3 will be omitted.

[0029] The pair of second rotating bodies 3 are disposed at an interval from each other in the axial direction. The first rotating body 2 is disposed between the pair of second rotating bodies 3. That is, the pair of second rotating bodies 3 are disposed so as to sandwich the first rotating body 2 in the axial direction. In detail, the outer flange portion 23 of the first rotating body 2 is disposed between the pair of second rotating bodies 3 in the axial direction.

[0030] The pair of second rotating bodies 3 are detachably attached to each other by a plurality of bolts 8a and nuts 8b, so that the pair of second rotating bodies 3 rotate integrally with each other.

[0031] The bolts 8a are configured to removably attach the pair of second rotating bodies 3 to each other. Specifically, the bolts 8a pass through through holes formed in each of the second rotating bodies 3 in the axial direction and are screwed into the nuts 8b. The pair of second rotating bodies 3 can be removed from each other by releasing the screwing of the bolts 8a and the nuts 8b. In addition, the pair of removed second rotating bodies 3 can be easily attached to each other by screwing the bolts 8a and the nuts 8b together.

[0032] Each stopper member 5 is disposed between the pair of second rotating bodies 3 in the axial direction. Each stopper member 5 is disposed in a cutout portion 26 of the first rotating body 2. The stopper members 5 are attached to the pair of second rotating bodies 3 so as to rotate integrally with the pair of second rotating bodies 3.

[0033] When the bicycle is traveling, when the torsion angle between the first rotating body 2 and the second rotating body 3 reaches a predetermined angle, the stopper surface 25 comes into contact with the stopper member 5. In this way, the stopper member 5 comes into contact with the stopper surface 25, thereby restricting the first rotating body 2 from rotating further relative to the pair of second rotating bodies 3. That is, the first rotating body 2 rotates relative to the pair of second rotating bodies 3 until the stopper member 5 comes into contact with the stopper surface 25. After the stopper member 5 comes into contact with the stopper surface 25, the first rotating body 2 rotates integrally with the pair of second rotating bodies 3. The torsion angle between the first rotating body 2 and the second rotating body 3 when the stopper surface 25 comes into contact with the stopper member 5 is referred to as the maximum torsion angle. When no torque is input to the power transmission device 100, the torsion angle between the first rotating body 2 and the second rotating body 3 is 0 degrees.

[0034] The stopper member 5 is attached to the pair of second rotating bodies 3 in a replaceable manner. Specifically, the stopper member 5 has a through hole 51 penetrating in the axial direction. The bolt 8a extends through the through hole 51 of the stopper member 5. The stopper member 5 can be replaced with another stopper member 5 by releasing the screw engagement between the bolt 8a and the nut 8b to remove the bolt 8a and by removing one of the pair of second rotating bodies 3 from the other. The stopper member 5 used in the power transmission device 100 can be selected from, for example, a plurality of types of stopper members having different circumferential sizes. In detail, the stopper member 5 can be selected from a plurality of types of stopper members having different outer diameters. By replacing the stopper member 5 in this way, the distance between the stopper surface 25 and the stopper member 5 can be changed, and the maximum torsional angle between the first rotating body 2 and the second rotating body 3 can be changed.

[0035] The second rotor 3 is disk-shaped and has a through hole in the center. The hub portion 22 of the first rotor 2 extends axially through the through hole of the second rotor 3.

[0036] The second rotating body 3 has a plurality of second housing portions 31. In this embodiment, the second rotating body 3 has three second housing portions 31. The second housing portions 31 are arranged at intervals in the circumferential direction.

[0037] The second housing portion 31 penetrates the second rotor 3 in the axial direction. The second housing portion 31 extends in the circumferential direction. Each of the second housing portions 31 is disposed on substantially the same circumference. The second housing portion 31 is disposed so as to face the first housing portion 21 in the axial direction. That is, the second housing portion 31 is disposed so as to overlap with the first housing portion 21 when viewed in the axial direction.

[0038] The second rotating body 3 has a first cut-and-raised portion 32 and a second cut-and-raised portion 33. The first cut-and-raised portion 32 and the second cut-and-raised portion 33 are formed by cutting and raising a part of the second rotating body 3.

[0039] The first cut-and-raised portion 32 is disposed radially outward from the elastic member 4. The second cut-and-raised portion 33 is disposed radially inward from the elastic member 4. The first and second cut-and-raised portions 32, 33 are configured to restrict axial movement of the elastic member 4.

[0040] The second rotating body 3 can be made of, for example, iron, stainless steel, carbon fiber reinforced plastic (CFRP), or the like.

[0041] A sprocket unit 6 is provided on one of the pair of second rotating bodies 3. For example, the sprocket unit 6 is a separate member from the second rotating body 3, and is attached to the second rotating body 3 by a bolt 8a and a nut 8b. The sprocket unit 6 rotates integrally with the pair of second rotating bodies 3. The sprocket unit 6 has a plurality of teeth on its outer circumferential end. A chain (not shown) is hung on this sprocket unit 6, and torque is transmitted from the sprocket unit 6 to a drive wheel (not shown) via the chain or the like.

[0042] <Elastic material> The elastic member 4 is accommodated in the first accommodation portion 21 and the second accommodation portion 31. The elastic member 4 is, for example, a coil spring. The elastic member 4 elastically connects the first rotating body 2 and the pair of second rotating bodies 3 in the rotational direction. That is, the torque from the first rotating body 2 is transmitted to the pair of second rotating bodies 3 via the elastic member 4. The elastic member 4 also rotates together with the first rotating body 2 and the pair of second rotating bodies 3. When transmitting the torque, the elastic member 4 contracts, so that the first rotating body 2 and the second rotating body 3 are twisted relative to each other. When the elastic member 4 is not contracted, the first rotating body 2 and the second rotating body 3 are not twisted, and the torsion angle is 0 degrees.

[0043] <Crank arm> The crank arm 7 is configured to rotate integrally with the first rotating body 2. That is, the crank arm 7 is disposed to be rotatable around a rotation axis O. The crank arm 7 is attached to an inner flange portion 24 of the first rotating body 2. In detail, the crank arm 7 is configured to be spline-fitted into the inner flange portion 24.

[0044] The crank arm 7 has an arm main body 71 and an attachment portion 72. The arm main body 71 extends in the radial direction. The attachment portion 72 extends in the axial direction from one of both ends of the arm main body 71. A pedal (not shown) is attached to the other of both ends of the arm main body 71.

[0045] The tip portion 721 of the mounting portion 72 has an outer diameter smaller than that of the other portions of the mounting portion 72. This tip portion 721 is spline-fitted to the inner flange portion 24. Also, the tip portion 721 penetrates the inner flange portion 24 in the axial direction. Then, the tip portion 721 is fixed to the inner flange portion 24 by crimping. In detail, by crimping the tip portion 721, the tip portion 721 and the inner flange portion 24 are closely attached to each other. Also, the outer diameter of the portion of the tip portion 721 protruding from the inner flange portion 24 is increased by the crimping process, and becomes larger than the inner diameter of the inner flange portion 24. As a result, the tip portion 721 does not come out of the inner flange portion 24, and it is possible to prevent the crank arm 7 and the first rotating body 2 from moving in a direction away from each other in the axial direction.

[0046] The mounting portion 72 has a mounting hole 722. This mounting hole 722 is rectangular when viewed in the axial direction. A crankshaft (not shown) fits into this mounting hole 722, and the crank arm 7 rotates integrally with the crankshaft.

[0047] <Operation> The operation of the power transmission device 100 configured as described above will be described. First, when a user pedals and torque is input to the first rotating body 2 via the crank arm 7, the first rotating body 2 rotates in a rotational direction R. Then, the torque is transmitted from the first rotating body 2 to the pair of second rotating bodies 3 via the elastic member 4. As a result, the pair of second rotating bodies 3 rotate in the rotational direction R, and the torque is transmitted to the drive wheels.

[0048] Here, when the elastic member 4 is compressed and the torsion angle between the first rotating body 2 and the second rotating body 3 reaches a predetermined angle, the stopper surface 25 comes into contact with the stopper member 5. As a result, the first rotating body 2 and the pair of second rotating bodies 3 rotate integrally. This maximum torsion angle can be changed by replacing the stopper member 5. For example, the maximum torsion angle can be reduced by replacing the stopper member 5 with a stopper member 5 having a larger outer diameter. Conversely, the maximum torsion angle can be increased by replacing the stopper member 5 with a stopper member 5 having a smaller outer diameter. The power transmission device 100 is configured so that the maximum torsion angle is reached before the elastic member 4 is fully compressed.

[0049] The elastic member 4 preferably has a spring constant such that the first rotating body 2 and the pair of second rotating bodies 3 have a maximum torsional angle when a torque of 100 N·m or less is input to the first rotating body 2. The elastic member 4 preferably has a spring constant such that the first rotating body 2 and the pair of second rotating bodies 3 have a maximum torsional angle when a torque of 20 N·m or more is input to the first rotating body 2. The torque input to the first rotating body 2 at the maximum torsional angle is referred to as the maximum torque. Although not particularly limited, for example, elastic members 4 having spring constants that make the maximum torque around 90 N·m, around 80 N·m, around 70 N·m, around 60 N·m, around 50 N·m, around 40 N·m, and around 30 N·m are prepared. The elastic member 4 may be configured so that the user can select from these elastic members 4 as appropriate.

[0050] [Variations] Although the embodiment of the present invention has been described above, the present invention is not limited to these, and various modifications are possible without departing from the spirit of the present invention. Note that the following modifications can basically be applied simultaneously.

[0051] (a) In the above embodiment, the crank arm 7 is attached to the first rotating body 2, and the sprocket portion 6 is provided on one of the pair of second rotating bodies 3, but the configuration of the power transmission device 100 is not limited to this. For example, as shown in Fig. 3, the crank arm 7 may be attached to one of the pair of second rotating bodies 3, and the sprocket portion 6 may be provided on the first rotating body 2.

[0052] (b) In the above embodiment, the sprocket unit 6 is configured as a separate member from the second rotating body 3, but the configuration of the sprocket unit 6 is not limited to this. For example, the sprocket unit 6 may be provided integrally with the outer circumferential end of the second rotating body 3. In other words, the sprocket unit 6 may be configured as a single member together with the second rotating body 3. In particular, the sprocket unit 6 may be configured by forming a plurality of teeth on the outer circumferential end of the second rotating body 3.

[0053] (c) In the above embodiment, the stopper member 5 has a through hole 51 through which the bolt 8a passes, but the configuration of the stopper member 5 is not limited to this. For example, the stopper member 5 may have a screw hole on each of both sides facing the axial direction. Then, a pair of bolts 8a may be screwed into each screw hole of the stopper member 5 from both sides in the axial direction, thereby fixing the pair of second rotating bodies 3 and the stopper member 5 to each other. Note that each screw hole may be connected to each other to form a single screw hole.

[0054] 4, the stopper member 5 may be rectangular in the axial direction. In this case, a plurality of stopper members 5 having different circumferential dimensions are prepared, and the distance between the stopper surface 25 and the stopper member 5 can be changed by replacing the stopper member 5. [Explanation of symbols]

[0055] 2: First rotating body 22: Hub section 23: Outer flange 24: Inner flange 25: Stopper surface 3: Second rotating body 4: Elastic material 5: Stopper member 51: Through hole 6: Sprocket part 7: Crank arm 71: Arm body 72: Mounting part 721:Tip 8a:Bolt 100: Power transmission device

Claims

1. A first rotor that is rotatably disposed; A pair of second rotating bodies arranged to sandwich the first rotating body in the axial direction and removably attached to each other; an elastic member that elastically connects the first rotating body and the pair of second rotating bodies; a stopper member disposed between the pair of second rotating bodies and attached to the pair of second rotating bodies; Equipped with The first rotating body has a stopper surface that faces the stopper member with a gap in between in a rotational direction. Bicycle power transmission device.

2. and a plurality of bolts configured to removably attach the pair of second rotating bodies to one another. The stopper member has a through hole passing therethrough in an axial direction, The bolt extends through the through hole.

2. The bicycle power transmission device according to claim 1.

3. a sprocket portion provided on one of the pair of second rotating bodies; A crank arm configured to rotate integrally with the first rotor; Further comprising:

2. The bicycle power transmission device according to claim 1.

4. The first rotating body is A hub portion extending in an axial direction; an outer flange portion extending radially outward from the hub portion; an inner flange portion extending radially inward from the hub portion; having The crank arm is attached to the inner flange portion.

4. The bicycle power transmission device according to claim 3.

5. The crank arm is spline-fitted to the inner flange portion.

5. The bicycle power transmission device according to claim 4.

6. The crank arm is An arm body portion extending in a radial direction; a mounting portion extending in an axial direction from an end portion of the arm body; having The mounting portion penetrates the inner flange portion and is fixed to the inner flange portion by crimping at a tip end thereof.

6. A bicycle power transmission device according to claim 4 or 5.

7. The stopper members are replaceably attached to the pair of second rotating bodies.

2. The bicycle power transmission device according to claim 1.

8. The stopper member is a stopper member selected from a plurality of types of stopper members having different circumferential sizes.

2. The bicycle power transmission device according to claim 1.

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