Power generator and gear shifter

Abstract

To provide a power generator that can be easily incorporated around a pulley and a gear shifter including the power generator.SOLUTION: A power generator 4 includes: a transmission member 3; a pulley 42 that meshes with the transmission member 3; a plurality of brackets 40, 41 that rotatably support the pulley 42; and a shaft 21 that transmits rotation of the pulley 42. The plurality of brackets 40, 41 face each other via a space 44. A part of the shaft 32 is arranged in the space 44. A rotor 26 is fixed to the shaft 21. A stator 27 surrounds the rotor 26.SELECTED DRAWING: Figure 4

Description

[Technical Field]

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

[0002] For example, Patent Document 1 discloses a chain tensioner device for supporting a bicycle chain. This chain tensioner device has a generator built into a pulley supported by a pair of pulley guides. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5358003 Summary of the Invention [Problem to be solved by the invention]

[0004] The generator is installed inside the pulley that applies tension to the chain. Installing the generator in the narrow space inside a small pulley is technically difficult. For example, installing it requires major design changes to the conventional pulley structure.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a generator that can be easily incorporated around a pulley and a transmission that includes the generator. [Means for solving the problem]

[0006] A power generation device according to one aspect of the present invention comprises a transmission member, a pulley that meshes with the transmission member, a plurality of brackets that rotatably support the pulley, and a shaft that transmits the rotation of the pulley, wherein the plurality of brackets face each other across a space, a portion of the shaft is positioned in the space, a rotor is fixed to the shaft, and the rotor is surrounded by a stator.

[0007] A transmission according to one aspect of the present invention includes the above-described power generation device. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a perspective view showing the schematic structure of a transmission 1 according to one embodiment of the present invention. [Figure 2] 1 is a side view showing a schematic structure of a transmission 1 according to an embodiment of the present invention. [Figure 3] 1 is a rear view that schematically shows the structure of a transmission 1 according to an embodiment of the present invention. [Figure 4] FIG. 4 is a cross-sectional view taken along line 4-4 in FIG. 2. [Figure 5] FIG. 5 is a cross-sectional view corresponding to FIG. 4 and schematically showing the structure of a transmission 1A according to another embodiment of the present invention. [Figure 6] FIG. 10 is a perspective view that schematically shows the structure of a transmission 1B according to still another embodiment of the present invention. [Figure 7] FIG. 10 is a side view that schematically shows the structure of a transmission 1B according to still another embodiment of the present invention. [Figure 8] FIG. 8 is a cross-sectional view taken along line 8-8 in FIG. 7. DETAILED DESCRIPTION OF THE INVENTION

[0009] An embodiment of the present invention will now be described with reference to the accompanying drawings. Fig. 1 is a perspective view that schematically shows the structure of a transmission 1 according to an embodiment of the present invention. Fig. 2 is a side view that schematically shows the structure of a transmission 1 according to an embodiment of the present invention. Fig. 3 is a rear view that schematically shows the structure of a transmission 1 according to an embodiment of the present invention. The transmission 1 is attached to an end 2c where a seat stay 2a and a chain stay 2b intersect on a frame 2 of, for example, a bicycle (including all types of bicycles such as road bikes, cross bikes, mountain bikes, and city bikes). In other words, the transmission 1 is what is known as a rear derailleur and is also an externally mounted transmission.

[0010] FIG. 1 shows the transmission 1 as seen from the left rear of the bicycle. Of the pair of left and right seat stays 2a and chain stays 2b, only the right seat stay 2a and chain stay 2b are shown in FIG. 1. For the sake of clarity, the rest of the configuration of the frame 2 has been omitted from the illustration. In the following description, the terms "front," "rear," "left," "right," "upward," and "downward" are defined based on the bicycle itself. Furthermore, "upward" and "downward" do not necessarily correspond to the up and down directions in the direction of gravity.

[0011] A rear wheel (not shown) is mounted on end 2c of frame 2 so as to be rotatable about a horizontally extending axis. The rear wheel has a multi-stage sprocket (not shown) located between the hub of the rear wheel and end 2c of frame 2. Transmission 1 is attached to end 2c so as to be located, for example, below the axis of the rear wheel. Transmission 1 can engage chain 3, which serves as a transmission member, with sprockets having different numbers of teeth by shifting the position of chain 3 in the direction along the sprocket axis. This is how bicycle gears are changed. Note that FIG. 1 shows chain 3 in a simplified form. For ease of explanation, chain 3 is not shown in FIGS. 2 and 3.

[0012] In this example, the transmission 1 is an electric type that changes gears when supplied with electric power. However, instead of an electric type, the transmission 1 may be a mechanical type that changes gears using, for example, a mechanical wire. The chain 3 is a roller chain made of, for example, a metal material. However, instead of the chain 3, a belt made of, for example, a resin material may be used as the transmission member. In this case, the bicycle sprockets and the guide pulleys and tension pulleys described below each have a structure corresponding to the belt.

[0013] 1 to 3, the transmission 1 includes a displacement mechanism 10, a motor 20, a plurality of first and second brackets 40 and 41, a guide pulley 42, a tension pulley 43, and a chain 3 serving as a transmission member. The displacement mechanism 10 includes a first section 11, a second section 12, and connecting members 13. The first section 11 is fixed to an end 2c of the frame 2. The connecting members 13 connect the first section 11 and the second section 12 so that the second section 12 can be displaced generally in the left-right direction of the bicycle relative to the first section 11. The displacement mechanism 10, the first bracket 40, the second bracket 41, the guide pulley 42, and the tension pulley 43 are formed, for example, from a metal material.

[0014] In the displacement mechanism 10, one end of each connecting member 13 is connected to the first portion 11, and the other end of each connecting member 13 is connected to the second portion 12. The second portion 12 is displaced relative to the first portion 11 as one end and the other end of each connecting member 13 swing relative to the first portion 11 and the second portion 12, respectively. In this manner, the second portion 12, motor 20, first bracket 40, second bracket 41, guide pulley 42, tension pulley 43, and chain 3 are displaced generally in the front-to-rear direction and diagonally in the left-to-right direction of the bicycle. This operation of the displacement mechanism 10 displaces the position of the guide pulley 42 relative to the sprocket. The displacement mechanism 10 may be realized in other configurations as long as the entire configuration, including the second portion 12, can be displaced diagonally in the front-to-rear direction and diagonally in the left-to-right direction.

[0015] A first bracket 40 is connected to the second part 12 of the displacement mechanism 10 so as to be able to swing about an axis x1. The first bracket 40 faces a second bracket 41 across a space 44. A motor 20 and a guide pulley 42 are disposed in the space 44 between the base ends 40a, 41a of the first bracket 40 and the second bracket 41. The motor 20 is fixed to the base end 40a of the first bracket 40. The motor 20 has a shaft 21 that can rotate about the axis x1. In this example, the axis x1 extends generally in the left-right direction. The guide pulley 42 is disposed closer to the rear wheel than the motor 20. The guide pulley 42 is connected to the shaft 21 of the motor 20. The guide pulley 42 has the function of guiding the chain 3 relative to the sprocket.

[0016] The first bracket 40 and the second bracket 41 extend from their base ends 40a and 41a to their tip ends 40b and 41b, respectively, in a direction perpendicular to the axis x1. A tension pulley 43 is disposed in a space 44 between the tip ends 40b and 41b of the first bracket 40 and the second bracket 41. The tension pulley 43 is supported by a shaft 45 fixed to the tip ends 40b and 41b so as to be relatively rotatable. The shaft 45 extends along the axis x2. The axis x2 is defined parallel to the axis x1. The shaft 45 is fixed to the tip ends 40b and 41b of the first bracket 40 and the second bracket 41, respectively.

[0017] The tension pulley 43 has the function of maintaining a constant tension applied to the chain 3. To apply this tension, the entire components of the transmission 1, including the first bracket 40, the second bracket 41, the motor 20, the guide pulley 42, and the tension pulley 43, can swing over a predetermined angle around the axis x1. An elastic member (not shown), such as a coil spring, incorporated into the transmission 1 constantly biases the entire components of the first bracket 40, the second bracket 41, the motor 20, the guide pulley 42, and the tension pulley 43 toward a predetermined position. The entire position of the transmission 1 can be changed depending on the position of the chain 3 on the sprocket.

[0018] Both the guide pulley 42 and the tension pulley 43 are pulleys having a plurality of teeth in the circumferential direction that mesh with the chain 3, which is, for example, a roller chain. However, as described above, the guide pulley 42 is configured to rotate together with the shaft 21, while the tension pulley 43 is configured to rotate relative to the shaft 45, in that they differ. Note that the first bracket 40 has a stepped portion 40c that approaches the second bracket 41 toward the tip 40b. As a result, the distance along the axis x1 of the space 44 between the base ends 40a, 41a is greater than the distance along the axis x2 of the space 44 between the tip ends 40b, 41b.

[0019] FIG. 4 is a cross-sectional view taken along line 4-4 in FIG. 2. The transmission 1 includes a power generator 4. FIG. 4 shows a schematic diagram of the structure of the power generator 4 according to one specific example. The power generator 4 according to one specific example includes a chain 3, a guide pulley 42, a pair of a first bracket 40 and a second bracket 41, and a motor 20. As will be described later, in the power generator 4 according to one specific example, when the chain 3 moves around an axis x1 while meshing with the guide pulley 42, the guide pulley 42 and the shaft 21 of the motor 20 rotate around the axis x1. The rotation of the shaft 21 generates electrical energy in the motor 20. This electrical energy may be used to operate the transmission 1, or may be used for other electronic components (such as wireless communication devices or small motors) mounted on the bicycle.

[0020] As shown in FIG. 4, the motor 20 has a housing 22. The housing 22 has a cylindrical main body 22a and a lid 22b that covers an opening formed at one end of the main body 22a in the direction along the axis x1. The main body 22a is formed in a cylindrical shape with the axis x1 as its central axis. An opening formed at the other end of the main body 22a in the direction along the axis x1 is closed. In this example, the shaft 21 penetrates the housing 22 along the axis x1. In this way, the main body 22a and the lid 22b form an accommodation space within the housing 22. Furthermore, a portion of the shaft 21 is disposed in the space 44. The housing 22 is formed, for example, from a metal material or a resin material with high thermal conductivity.

[0021] The shaft 21 is rotatably supported around the axis x1 by, for example, three bearings: a first bearing 23, a second bearing 24, and a third bearing 25. The first bearing 23, the second bearing 24, and the third bearing 25 are, for example, ball bearings. The first bearing 23 is mounted in a recess 41c formed in the second bracket 41. The second bearing 24 is mounted in a recess 22c formed in the lid 22b. The third bearing 25 is mounted in a recess 40d formed in the first bracket 40. In this way, one end of the shaft 21 in the direction along the axis x1 is rotatably mounted to the first bracket 40, while the other end of the shaft 21 in the direction along the axis x1 is rotatably mounted to the second bracket 41.

[0022] The shaft 21 is detachably supported by the guide pulley 42. For example, the guide pulley 42 is attached to the shaft 21 by press-fitting. Alternatively, the shaft 21 may have a D-cut shape in a cross section perpendicular to the axis x1, and the guide pulley 42 may have a hole having a cross section with a corresponding D-cut shape. Alternatively, a key groove may be formed on the outer circumferential surface of the shaft 21, while a key corresponding to the key groove may be formed in the hole of the guide pulley 42. In this way, the guide pulley 42 can rotate together with the shaft 21.

[0023] The motor 20 has a rotor 26 fixed to the shaft 21 and a stator 27 surrounding the rotor 26. The rotor 26 and the stator 27 are arranged in a space 44. The rotor 26 is fixed to the outer circumferential surface of the shaft 21. The rotor 26 is, for example, a magnet 28. The magnet 28 is, for example, a permanent magnet. The magnet 28 is formed, for example, in a cylindrical shape with the axis x1 as its central axis. The magnet 28, i.e., the rotor 26, rotates together with the shaft 21 around the axis x1. In this way, the rotor 26 can rotate relative to the stator 27 around the axis x1. In other words, the motor 20 is a so-called inner rotor type motor.

[0024] On the other hand, the stator 27 has a coil 29 and a yoke, i.e., a stator core 30. The outer peripheral surface of the stator core 30 is attached to the inner peripheral surface of the main body 22a of the housing 22. Thus, the stator core 30, i.e., the stator 27, is in contact with the inner peripheral surface of the main body 22a of the housing 22. The stator core 30 is formed from a laminated body in which multiple annular silicon steel plates (or electromagnetic steel plates) are stacked in a direction along the axis x1. The stator core 30 surrounds the shaft 21. Conductive wires forming the coils 29 are wound around multiple spokes of the stator core 30 extending radially, perpendicular to the axis x1. Note that an insulator (not shown) having electrical insulation properties is disposed between the coils 29 and the spokes of the stator core 30. The inner peripheral surface of the stator core 30 faces the outer peripheral surface of the magnet 28 of the rotor 26 with a predetermined magnetic gap between them.

[0025] In this generator 4, when a bicycle user pedals, the chain 3 moves around axis x1 and axis x2 while meshing with the guide pulley 42 and tension pulley 43, respectively. This movement of the chain 3 causes the guide pulley 42 and tension pulley 43 to rotate around axis x1 and axis x2, respectively. As the guide pulley 42 rotates together with the shaft 21, in the motor 20, magnetic interaction between the magnet 28 and the coil 29 generates electrical energy in the coil 29. The generated electrical energy is used, for example, in the transmission 1. Specifically, the electrical energy is used to, for example, move the position of the chain 3 in the transmission 1.

[0026] In the transmission 1 described above, the rotation of the guide pulley 42, which is rotatably supported by a pair of first and second brackets 40 and 41, about the axis x1 is transmitted to the shaft 21. As a result, electrical energy is generated in the motor 20. The motor 20 is disposed in the space 44 between the first and second brackets 40 and 41. Therefore, no significant design changes are required for the guide pulley 42. In this way, the generator 4 can be easily incorporated in a position adjacent to the guide pulley 42. Moreover, because the generator 4 can be incorporated within the transmission 1, there is no need for wiring to the transmission 1 as in the past.

[0027] Furthermore, in the motor 20, the main body 22a of the housing 22 has a portion that is open, but this opening is closed by the lid 22b. A sealed space can be formed within the housing 22. As a result, the intrusion of dust, water, etc. into the motor 20 can be suppressed. Moreover, in the motor 20, the stator core 30 is in contact with the inner circumferential surface of the housing 22. On the other hand, the outer circumferential surface of the housing 22 is in contact with the air. Even if the coil 29 generates heat in generating electrical energy, the heat can be efficiently released into the air through the stator core 30 and the housing 22. Excessive heat generation in the motor 20 can be suppressed. As a result, the performance of the motor 20 can be improved.

[0028] FIG. 5 corresponds to FIG. 4 and is a cross-sectional view schematically illustrating the structure of a transmission 1A according to another embodiment of the present invention. As shown in FIG. 5, a power generation device 4A is incorporated into the transmission 1A instead of the power generation device 4 described above. In this power generation device 4A, a power storage device 50 is added to the power generation device 4. Other components similar to those of the transmission 1 described above are denoted by the same reference numerals, and redundant description will be omitted. In this power generation device 4A, the power storage device 50 is housed within the housing 22 of the motor 20. The power storage device 50 is a small storage battery or the like. In this example, the power storage device 50 is disposed within the housing 22 between the lid 22b and the rotor 26 and stator 27. Such a power storage device 50 can store electrical energy generated by the motor 20. Alternatively, the power storage device 50 may be a capacitor mounted on a circuit board (not shown). The power storage device 50 may also be disposed outside the motor 20.

[0029] FIG. 6 is a perspective view schematically showing the structure of a transmission 1B according to yet another embodiment of the present invention. FIG. 7 is a side view schematically showing the structure of a transmission 1B according to yet another embodiment of the present invention. FIG. 8 is a cross-sectional view taken along line 8-8 in FIG. 7. Note that the chain 3, which is a transmission member, is not shown in FIGS. 6 to 8. Referring to FIGS. 6 to 8 together, this transmission 1B incorporates a generator 4B in place of the generators 4, 4A described above. In this generator 4B, the shaft 21 of the motor 20 is supported by a tension pulley 43. Meanwhile, the guide pulley 42 is rotatably supported by a shaft 36. Other components similar to those described above are designated by the same reference numerals, and redundant description will be omitted here.

[0030] In the power generation device 4B, the step portion 30c of the first bracket 40A is omitted. That is, a space 44 between the first bracket 40A and the second bracket 41 extends with a constant width in a direction perpendicular to the axis x1. A shaft 46 extending along the axis x1 is fixed to the base ends 40a and 41a of the first bracket 40A and the second bracket 41. A guide pulley 42 is supported so as to be rotatable relative to the shaft 46. Meanwhile, a tension pulley 43 supported on the tip ends 40b and 41b of the first bracket 40A and the second bracket 41 is fixed to the shaft 21 of the motor 20. In this example, the tension pulley 43 is disposed in the space 44, while the motor 20 is disposed outward of the first bracket 40A.

[0031] The shaft 21 is rotatably supported around the axis x2 by, for example, three bearings: a fourth bearing 31, a fifth bearing 32, and a sixth bearing 33. The fourth bearing 31, the fifth bearing 32, and the sixth bearing 33 are, for example, ball bearings. The fourth bearing 31 is mounted in a recess 41d formed in the second bracket 41. The fifth bearing 32 is mounted in a recess 40e formed in the first bracket 40A. The sixth bearing 33 is mounted in a recess 22d formed in the main body 22a of the housing 22. In this way, the shaft 21 is rotatably mounted to the first bracket 40A and the second bracket 41 adjacent to one end of the shaft 21 in the direction along the axis x2. As described above, the shaft 21 is detachably supported by the guide pulley 42.

[0032] In this generator 4B, when a bicycle user pedals, the chain 3 moves around axis x1 and axis x2 while meshing with the guide pulley 42 and tension pulley 43, respectively. This movement of the chain 3 causes the guide pulley 42 and tension pulley 43 to rotate around their respective axes x1 and x2. As the tension pulley 43 rotates together with the shaft 21, in the motor 20, magnetic interaction between the magnet 28 and the coil 29 generates electrical energy in the coil 29. The generated electrical energy is used, for example, in the transmission 1A.

[0033] In the transmission 1B described above, the rotation of the tension pulley 43, which is rotatably supported by a pair of first and second brackets 40 and 41, about the axis x2 is transmitted to the shaft 21. As a result, electrical energy is generated in the motor 20. The motor 20 is disposed outside the space 44. Therefore, no significant design changes are required for the tension pulley 43. In this way, the generator 4B can be easily incorporated in a position adjacent to the tension pulley 43. Moreover, because the generator 4B can be incorporated within the transmission 1B, there is no need for wiring to the transmission 1B as in the past.

[0034] In the above-described bicycles, in the generator 4, 4A of the transmission 1, 1A, the motor 20 is disposed in the space 44 between the first bracket 40 and the second bracket 41, and therefore the motor 20 is formed relatively thin along the axis x1. Therefore, the motor 20 in this case is formed relatively large in the radial direction. On the other hand, in the generator 4B of the transmission 1B, the motor 20 is disposed outside the space 44 in the direction along the axis x2, and therefore the motor 20 is formed relatively thick along the axis x2. The motor 20 in this case is formed relatively small in the radial direction. However, because the motor 20 of the generator 4B protrudes outward to the right of the bicycle, the size of the motor 20 is set to a value that will prevent the motor 20 from contacting the ground when the bicycle is traveling with the bicycle leaning to the right.

[0035] The above-described embodiments are intended to facilitate understanding of the present invention and are not intended to limit the scope of the present invention. Furthermore, the above-described embodiments do not limit the scope of the present invention, and the present invention may include any and all applications. The components of the above-described embodiments, as well as their arrangement, materials, conditions, shape, size, etc., are not limited to those illustrated and may be modified as appropriate. For example, the present invention includes differences that arise during implementation due to manufacturing tolerances, etc. Furthermore, components illustrated in different embodiments may be partially substituted or combined within the scope of technical inconsistency. Furthermore, the various configurations may be selectively combined as appropriate to achieve at least some of the above-described problems and effects. [Explanation of symbols]

[0036] 1, 1A, 1B Transmission device, 2 Frame, 2a Seat stay, 2b Chain stay, 2c End, 3 Chain (transmission member), 4, 4A, 4B Generator, 10 Displacement mechanism, 11 First part, 12 Second part, 13 Connecting member, 20 Motor, 21 Shaft, 22 Housing, 22a Main body, 22b Cover, 22c Recess, 22d Recess, 23 First bearing, 24 Second bearing, 25 Third bearing, 26 Rotor, 27 Stator, 28 Magnet, 29 Coil, 30 Stator core, 31 Fourth bearing, 32 Fifth bearing, 33 Sixth bearing, 40 First bracket, 40a Base end, 40b Tip, 40c Step portion, 40d Recess, 40e Recess, 41 Second bracket, 41a Base end, 41b Tip, 41c Recess, 41d Recess, 42 guide pulley, 43 tension pulley, 44 space, 45 shaft, 46 shaft, 50 power storage device, x1 axis, x2 axis

Claims

1. A transmission member; a pulley that meshes with the transmission member; a plurality of brackets that rotatably support the pulley; a shaft that transmits the rotation of the pulley, The plurality of brackets face each other across a space, A portion of the shaft is disposed in the space, A rotor is fixed to the shaft, The rotor is surrounded by a stator.

2. The power generating device according to claim 1 , wherein the shaft is detachably supported relative to the pulley.

3. The power generating device according to claim 1 or 2, wherein the rotor and the stator are disposed in the space.

4. The plurality of brackets include at least one pair of brackets facing each other, 4. The power generating device according to claim 1, wherein the shaft is rotatably attached to one of the pair of brackets and the other of the pair of brackets.

5. The stator and the rotor are housed in a partially open housing, The power generating device according to any one of claims 1 to 4, wherein the opening is closed by a lid.

6. the stator is in contact with the inner surface of the housing; The power generating device according to any one of claims 1 to 5, wherein the outer surface of the housing is in contact with air.

7. The power generating device according to claim 5 or 6, wherein the housing accommodates an electricity storage device.

8. A transmission comprising the power generating device according to any one of claims 1 to 7.

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