Compact generator

Abstract

Provided is a compact generator 6. The compact generator 6 comprises: a power generation member 80 which is provided coaxially with a rotating member 3 and which converts the rotational force of the rotating member 3 into electric power; and a speed change member 50 which is provided coaxially with the rotating member 3 and the power generation member 80 and which is interposed between the rotating member 3 and the power generation member 80. A cycloidal transmission is used in the speed change member 50. Thus, the rotation of the rotating member 3 is accelerated and transmitted to the power generation member 80.

Description

Small generator

[0001] The disclosed technology relates to a small generator suitable for being assembled into a hub dynamo, a pipe, or the like.

[0002] In general, a bicycle may sometimes be equipped with a small generator that supplies electric power to a headlight using the rotational force of wheels. As this type of generator, a rim drive type dynamo that generates power by being pressed against the rim of a rotating front wheel from the side during power generation is widely known. However, this rim drive type has the disadvantages of a large load on the wheels and increased pedaling resistance.

[0003] Accordingly, in recent years, hub dynamos in which a generator is incorporated into a rotating hub located at the center of a wheel have been widely used.

[0004] For example, the hub dynamo disclosed in Patent Document 1 includes a rotatable hub case and a non-rotatable hub shaft extending through the center of the hub case. A cylindrical permanent magnet is internally fitted to the inner peripheral surface of the hub case. A core (iron core) having four-pole teeth is fixed to the hub shaft. A coil is formed by winding an electric wire around each tooth. When the hub case rotates, a current flows through the coil, and the current is output.

[0005] However, conventional hub dynamos are heavy due to the inclusion of the core, which is disadvantageous for bicycles. Moreover, cogging torque is generated due to the attractive force acting between the core and the permanent magnet. Cogging torque becomes an unnecessary load that increases pedaling resistance.

[0006] In order to suppress cogging torque, a hub dynamo using a coreless motor has been proposed (Patent Document 2).

[0007] In addition to hub dynamos, small generators that generate power using existing facilities through which water flows have also been proposed. For example, Patent Document 3 discloses a hydroelectric power generation unit that is attached to a water pipe to generate power.

[0008] Japanese Patent Application Laid-Open No. 06-048341, Japanese Patent Application Laid-Open No. 2016-171723, Japanese Patent Application Laid-Open No. 2004-285953

[0009] The hub dynamo described in Patent Document 2 rotates a coreless cylindrical coil section. Therefore, the generation of cogging torque can be suppressed. However, in that coreless motor, the coil section and the magnet sections facing each other are fixed to the axle. Therefore, the rotational speed of the hub and the coil section are the same.

[0010] On the other hand, coreless motors have weaker magnetic fields compared to motors with a core. Therefore, their power generation is lower. To increase power generation, a gear unit composed of multiple spur gears is interposed between the hub and the coil section, thereby increasing the rotation speed of the hub.

[0011] However, the transmission efficiency tends to deteriorate when there are many gear stages in a spur gear system. Furthermore, the structure of the gear unit is complex. Therefore, high precision is required for the parts and assembly. The meshing of gears can also cause tooth damage, making the system prone to failure.

[0012] Furthermore, because the magnets of the coreless motor are fixed to the hub shaft, it is difficult to remove the motor from the hub shaft, making motor replacement difficult.

[0013] Patent Document 3 discloses the interposition of a transmission (41) between a hydraulically rotating impeller (13) and a motor-type power generation unit (26) (Figure 6). However, this transmission (41) is also composed of spur gears.

[0014] Therefore, this specification discloses technologies that enable the realization of high-performance, compact power generators.

[0015] The technology being disclosed relates to small-scale generators.

[0016] The small generator comprises a rotating member that rotates around a base axis due to the action of an external force, a power generation member provided coaxially with the rotating member and converting the rotational force of the rotating member into electricity, and a speed change member provided coaxially with the rotating member and the power generation member and interposed between the rotating member and the power generation member. A cycloidal transmission is used in the speed change member to increase the rotational speed of the rotating member and transmit it to the power generation member.

[0017] This small generator employs a cycloidal transmission as the speed-shifting member interposed between the coaxially mounted rotating member and the power-generating member. A cycloidal transmission can achieve a higher gear ratio per step than spur gears or planetary gears. Therefore, it enables miniaturization, weight reduction, and increased efficiency of the transmission mechanism. It allows for efficient and stable speed increases of the rotating member, thereby improving power generation efficiency.

[0018] The speed-shifting member may include a thrust bearing that rotates around the base shaft.

[0019] This will result in more stable rotation and further improve power generation efficiency.

[0020] The speed-shifting member comprises a first rotating body that rotates around the base axis, a second rotating body that rotates around the base axis at increased speed, a cycloidal disc disposed between the first and second rotating bodies, and a fixed ring disposed on the outer circumference of the cycloidal disc in a non-rotatable state. The second rotating body has an eccentric boss portion that rotatably supports the cycloidal disc around an eccentric axis that is eccentric with respect to the base axis. The cycloidal disc has a plurality of engaging teeth formed at equal intervals along its outer edge and a plurality of engaging holes that open on its surface and are formed at equal intervals along a circumference centered on the eccentric axis. The first rotating body has a plurality of engaging portions formed at equal intervals along a circumference centered on the base axis and that partially contact the inner surfaces of the plurality of engaging holes. The fixed ring has a plurality of internal teeth that partially mesh with the plurality of engaging teeth, and the internal teeth may be made of bearings.

[0021] This allows the power generation member to be easily connected coaxially to the speed change member, and the rotational force amplified by the speed change member can be smoothly transmitted to the power generation member. This makes it relatively easy to increase power generation efficiency. Furthermore, the smooth rotation of the bearings significantly reduces frictional resistance at the parts that partially contact each other during rotation to transmit rotational force. This is particularly effective at high rotational speeds. Therefore, power generation efficiency can be increased.

[0022] The speed-shifting member may be supported by a base shaft that extends coaxially with the base shaft.

[0023] This allows for stable support of the gear shifting components.

[0024] The power generation member may include an input shaft that rotates around the base axis, a rotor that includes a magnet and is fixed around the input shaft, and a stator that includes a coil and a core and is arranged around the rotor with an air gap between them, wherein the input shaft has an insertion hole that extends in the direction of the base axis, and the base shaft is inserted into the insertion hole with a gap between it and the inner circumferential surface of the insertion hole.

[0025] This allows the power generation component, even if it is an inner rotor type, to be arranged coaxially with the speed change component with a simple structure. The power generation component can be easily made brushless. Therefore, it has excellent durability. By making the input shaft a hollow structure and inserting the base shaft into it, the power generation component can be easily removed from the small generator and replaced. Making the input shaft hollow allows for coaxial arrangement with shafts of various shapes, enabling installation in a wide range of applications.

[0026] The small generator may be attached to a hub dynamo that makes up a bicycle wheel, and generate electricity through the rotation of the wheel.

[0027] This would allow for the creation of a lightweight, low-load, and high-performance hub dynamo with excellent power generation capabilities. As a result, cyclists would be able to ride their bikes smoothly even at night.

[0028] The aforementioned small generator may also generate electricity through the flow of a fluid.

[0029] This would allow it to be integrated into existing plumbing fixtures, and generate electricity easily using water flow.

[0030] The small generator also comprises a rotating member that rotates around a base axis by the action of an external force, a power generation member provided coaxially with the rotating member and converting the rotational force of the rotating member into electricity, and a speed change member provided coaxially with the rotating member and the power generation member and interposed between the rotating member and the power generation member. The power generation member may have an input shaft that rotates around the base axis, a rotor including a magnet and fixed around the input shaft, and a stator including a coil and a core and arranged around the rotor with an air gap, and the input shaft may have an insertion hole that extends in the direction of the base axis.

[0031] This compact generator allows the power generation component, even if it is an inner rotor type, to be mounted coaxially with the speed control component with a simple structure. The power generation component can be easily made brushless. Therefore, it offers superior durability. Because the input shaft has a hollow structure, the power generation component can be easily replaced. Coaxial mounting with various shafts is possible, allowing it to be installed in a wide range of applications.

[0032] The disclosed technology enables the realization of high-performance, compact generators. Furthermore, if the power generation components have a hollow structure, replacement of these components becomes easier. Coaxial mounting is also facilitated, allowing for installation in a variety of applications. Therefore, utilizing this technology in hub dynamos, power supplies for plumbing systems, and other applications can improve their performance.

[0033] This is a schematic diagram illustrating a preferred application example of the disclosed technology (hub dynamo). This is a schematic cross-sectional view showing the inside of the hub dynamo. This is a schematic cross-sectional view taken from the direction of arrow Y1 in Figure 2A. This is a schematic cross-sectional view of a cycloidal speed increaser. This is a schematic cross-sectional view of a cycloidal speed increaser. This is a schematic cross-sectional view taken from the direction of arrow Y3 in Figure 3A. This is an explanatory diagram of a thrust bearing. This is a schematic diagram for illustrating the detailed structure of a cycloidal speed increaser. This is a schematic diagram for illustrating the detailed structure of a cycloidal speed increaser. This is a schematic diagram for illustrating the structure of a slotless brushless motor. This is a schematic diagram illustrating another preferred application example of the disclosed technology (micro-generator).

[0034] The following describes the technologies being disclosed. However, the following description is essentially illustrative.

[0035] <First Embodiment> As one preferred application example of the disclosed technology, Figure 1 illustrates a hub dynamo 1 that is assembled to a bicycle wheel 100. Figure 2A shows a schematic cross-sectional view of the inside of the hub dynamo 1. Figure 2B shows a schematic cross-sectional view as seen from the direction of arrow Y1 in Figure 2A.

[0036] Typically, a bicycle wheel 100 consists of a tire 101, a rim 102, spokes 103, a hub 1, etc. The rim 102 is an annular part that supports the tire 101. The tire 101 is press-fitted onto the outer circumference of the rim 102.

[0037] The hub 1 is a part located at the center of the rim 102 and the tire 101, and rotatably supports them. The hub 1 comprises a hub shaft 2 (corresponding to the base shaft) which is supported in a non-rotatable state by the bicycle fork 104, and a hub body 3 (corresponding to the rotating member) which is rotatably supported on the hub shaft 2. The hub body 3 rotates around a base axis J1 which passes through the center of the hub shaft 2.

[0038] The hub body 3 has a cylindrical (hollow) cylinder portion 31 extending around the hub shaft 2, and a pair of disc portions 32, 32 integrated at both ends of the cylinder portion 31. A power generation unit 6 (corresponding to a small generator) is housed within the cylinder portion 31 (the power generation unit 6 will be described later). Thus, the hub dynamo 1 is formed. In other words, in this embodiment, the hub 1 described above corresponds to the hub dynamo (hereinafter referred to as hub dynamo 1).

[0039] Each disc portion 32 is provided with an annular flange portion 32a on its outer edge. Multiple spoke holes 32b are formed in each of these flange portions 32a. The hub body 3 is connected to the rim 102 via multiple spokes 103 attached to these spoke holes 32b.

[0040] Both end portions of the hub shaft 2 protrude from the hub body 3. These both end portions are fixed to a bicycle fork 104. As shown in FIG. 2A, the hub dynamo 1 further includes a pair of hub bearings 5, 5.

[0041] A hub boss portion 32c is provided at a central portion of each disk portion 32. Each hub bearing 5 is internally fitted to these hub boss portions 32c. The hub body 3 is rotatably pivotally supported on the hub shaft 2 via these hub bearings 5.

[0042] (Power Generation Unit) The power generation unit 6 included in the hub dynamo 1 converts the rotational force of a wheel 100 rotating about a base axis J1 into DC power and outputs the DC power. The power generation unit 6 is configured using a predetermined speed change member and a predetermined power generation member.

[0043] That is, a slotless brushless motor is used as the power generation member. The power generation unit 6 generates power using the slotless brushless motor (hereinafter, the slotless brushless motor is also simply referred to as "brushless motor 80"). Since a brushless motor 80 does not generate cogging torque, it can rotate with small torque and good response. Further, unlike a brushed motor, the brushless motor 80 does not have a brush that slides in contact with a commutator. Therefore, it is excellent in durability.

[0044] As the speed change member, a partially modified cycloid type speed reducer (cycloid speed reducer) is used. In the power generation unit 6, the cycloid speed reducer is used as a speed increaser (hereinafter, also referred to as cycloid speed increaser 50). With the cycloid speed increaser 50, the speed reduction ratio per stage can be increased. Therefore, the rotational force can be smoothly transmitted to the power generation member. High-rotation transmission can be achieved with low energy loss. Note that, when the hub shaft 2 is inserted into the input shaft 81 of the power generation member with a gap therebetween, the speed change member may be configured using a planetary gear mechanism, a spur gear mechanism, or the like.

[0045] The cycloid speed increaser 50 is centered on a reference axis J1 and is disposed coaxially with the hub shaft 2. This allows the cycloid speed increaser 50 to be easily attached to the hub shaft 2 and stably supported in a state where the centers are aligned.

[0046] The brushless motor 80 is also centered on the reference axis J1 and is disposed coaxially with the hub shaft 2. However, the brushless motor 80 has a hollow input shaft 81, which will be described later. The hub shaft 2 is inserted into the input shaft 81 with a gap therebetween. The brushless motor 80 is attached to the cycloid speed increaser 50. Thereby, the brushless motor 80 is integrated with the cycloid speed increaser 50.

[0047] That is, in the power generation unit 6 of this embodiment, one cycloid speed increaser 50 is attached to the non-rotatable hub shaft 2. Independently of the hub shaft 2, one brushless motor 80 is coupled to the cycloid speed increaser 50 which is disposed coaxially and side-by-side. By this arrangement, the brushless motor 80 can be easily attached to and detached from the small generator. It can be easily replaced, resulting in excellent convenience.

[0048] (Rotational force input / output transmission mechanism in speed change member) An input-side rotational force transmission mechanism 20 that connects the cylinder portion 31 and the cycloid speed increaser 50 is provided therebetween. 2A and 2B show, as an example thereof, the input-side rotational force transmission mechanism 20 including input-side internal teeth 21 and an input-side pinion 22.

[0049] An annular input-side internal tooth 21 is assembled to the inner circumference of the cylinder portion 31. On the other hand, the input-side pinion 22 is assembled to the cycloid speed increaser 50. The input-side pinion 22 is configured to mesh with a group of teeth formed along the inner peripheral edge of the input-side internal teeth 21.

[0050] Thereby, the rotational force of the hub body 3 is transmitted to the cycloid speed increaser 50 through the input-side rotational force transmission mechanism 20.

[0051] A disc-shaped second rotating body 52 (details to be described later) is provided on the output side of the cycloid speed increaser 50. This second rotating body 52 is connected to the input shaft 81 of the brushless motor 80 via an input member 85, which will be described later.

[0052] As a result, the rotational force of the second rotating body 52, which has been accelerated by the cycloid speed increaser 50, is transmitted to the brushless motor 80.

[0053] In the power generation unit 6 configured in this way, the cycloidal speed increaser 50 increases the rotational speed of the wheel 100 and transmits it to the brushless motor 80. The brushless motor 80 then generates electricity with this increased rotational speed. Therefore, it can generate electricity efficiently in a lightweight and compact size. No cogging torque is generated. A high-performance hub dynamo 1 can be realized.

[0054] (Cycloid Speed ​​Increaser) Figures 3A and 3B show cross-sectional views of the cycloid speed increaser 50. Figure 4 shows a schematic cross-sectional view from the direction of arrow Y3 in Figure 3A.

[0055] Figures 3A and 3B show the input and output directions for the cycloidal speed increaser 50. For convenience, the input and output directions used in the explanation will follow these figures.

[0056] The cycloidal speed increaser 50 consists of a cylindrical member whose diameter is greater than its length. The cycloidal speed increaser 50 is composed of a support base 51, a second rotating body 52, a second spacer ring 53, a cycloidal disc 54, a fixing ring 55, a first spacer ring 56, a first rotating body 57, a cover 58, a support cylinder 70, and the like.

[0057] The support cylinder portion 70 is made of a cylindrical member. The hub shaft 2 is inserted into the support cylinder portion 70, and the support cylinder portion 70 and the hub shaft 2 are integrated. On the outer circumference of the support cylinder portion 70, the cover 58, the first spacer ring 56, the fixing ring 55, the second spacer ring 53, and the support base 51 are arranged in this order from the input side.

[0058] The cover 58 is attached to the support cylinder portion 70. The first spacer ring 56, the fixing ring 55, and the second spacer ring 53 are assembled integrally to the support base 51 with multiple fixing bolts 59, with their outer circumferences overlapping in this order from the input side. Therefore, these components are not rotatable.

[0059] In contrast, the first rotating body 57, the cycloidal disk 54, and the second rotating body 52 are rotatable. That is, the first rotating body 57 and the second rotating body 52 rotate around the base axis J1. On the other hand, the cycloidal disk 54 is positioned between the first rotating body 57 and the second rotating body 52 and rotates around an eccentric axis J2 that is eccentric with respect to the base axis J1.

[0060] The support base 51 is a disc-shaped member centered on the base axis J1. A large-diameter recess 51a is coaxially formed on the output end face of the support base 51 (see Figure 8). A boss portion 82c provided on the housing 82 of the brushless motor 80 is attached to the recess 51a. In this way, the cycloidal speed increaser 50 and the brushless motor 80 are integrated.

[0061] As shown in Figure 3B, a cylindrical output-side pivot boss 51b is provided in the center of the support base 51. An output-side ball bearing 60 for pivoting is fitted into the output-side pivot boss 51b. The second rotating body 52 is pivotally supported on the support base 51 via the output-side ball bearing 60. The second rotating body 52 is a disc-shaped member that rotates around the base axis J1.

[0062] The central portion of the second rotating body 52 is provided with a cylindrical coaxial boss portion 52a and an eccentric boss portion 52b. The support cylinder portion 70 penetrates the coaxial boss portion 52a and the eccentric boss portion 52b. The coaxial boss portion 52a is located on the output side. The coaxial boss portion 52a is centered on the base axis J1.

[0063] A connecting hole is formed in the coaxial boss portion 52a, centered on the base shaft J1. A cylindrical input member 85, having an inner diameter larger than that of the support cylinder portion 70 and the input shaft 81, is press-fitted into this connecting hole for connection to the brushless motor 80. A rotation-preventing mechanism is provided between the connecting hole and the input member 85 to prevent free rotation. The second rotating body 52 and the input member 85 are integrated into one unit.

[0064] On the other hand, the eccentric boss portion 52b is located on the input side. The eccentric boss portion 52b is centered on an eccentric axis J2 that is eccentric with respect to the base axis J1. An intermediate ball bearing 61 for supporting the disc is fitted to the eccentric boss portion 52b. As shown in Figure 3A, a balance adjustment hole 52d is formed on the outer circumference of the second rotating body 52 to correct the imbalance caused by the eccentricity.

[0065] The cycloidal disc 54 is a thin, disc-shaped component. The cycloidal disc 54 is rotatably supported on the second rotating body 52 via an intermediate ball bearing 61. Therefore, the cycloidal disc 54 rotates around the eccentric axis J2. As a result, when the second rotating body 52 rotates, the cycloidal disc 54 rotates while sliding radially according to the amount of eccentricity (eccentric rotation).

[0066] As shown in Figure 4, the cycloidal disc 54 has a plurality of engagement teeth 54a (23 in this embodiment) formed at equal intervals along its outer periphery, and a plurality of engagement holes 54b (8 in this embodiment) opening into its surface. Each of the engagement teeth 54a is formed in a cycloidal tooth shape at equal intervals in the circumferential direction. The center of these engagement teeth 54a is the eccentric axis J2, and the engagement teeth 54a are eccentric with respect to the base axis J1.

[0067] On the other hand, each of the engagement holes 54b is formed as a circular hole of a predetermined diameter. These engagement holes 54b are formed at equal intervals along the circumference centered on the eccentric axis J2. In other words, the engagement holes 54b are also eccentric with respect to the base axis J1.

[0068] The second spacer ring 53 is a thin, annular member. With the second rotating body 52 supported by the output-side ball bearing 60, the outer circumference of the second spacer ring 53 is assembled to the input-side end face of the support base 51.

[0069] To increase the power generation efficiency of the cycloidal speed increaser 50, the outer circumference of the second rotating body 52 can be clamped between the support base 51 and the second spacer ring 53 via a pair of thrust bearings 63, 63. However, if sufficient power generation efficiency can be obtained for the intended use, the thrust bearings 63 may not be necessary. Furthermore, the size of the thrust bearings 63 can be appropriately selected according to the size of the cycloidal speed increaser 50.

[0070] Figure 5 shows a thrust bearing 63. The thrust bearing 63 consists of a ring-shaped retainer 63a and a plurality of hard balls 63b. The retainer 63a has a plurality of ball holes 63c formed at equal intervals in the circumferential direction.

[0071] A thrust bearing 63 is formed by inserting a hard ball 63b into each of these ball holes 63c. A pair of thrust bearings 63, 63 of this structure are interposed between the support base 51 and the second spacer ring 53. As a result, the outer circumference of the second rotating body 52 is supported so as to be able to rotate freely.

[0072] As a result, the second rotating body 52 can rotate stably without tilting, thereby increasing power generation efficiency. Furthermore, as will be described later, by providing multiple pairs of thrust bearings, the first rotating body 57, the second rotating body 52, and the cycloidal disc 54 can rotate stably without tilting, thereby increasing power generation efficiency.

[0073] The fixing ring 55 is an annular member. The fixing ring 55 is assembled to the input side of the second spacer ring 53. As a result, the fixing ring 55 is positioned non-rotatably on the outer circumference of the cycloidal disc 54. The fixing ring 55 has an annular outer edge portion 55a, a tooth support portion 55b that protrudes inward in an annular manner from the outer edge portion 55a, and a plurality (24 in this embodiment) of internal teeth 55c.

[0074] As shown in Figure 4, these internal teeth 55c are configured to partially mesh with the engaging teeth 54a of the cycloidal disc 54 to transmit rotational force.

[0075] In this embodiment, these internal teeth 55c are made up of ball bearings. Specifically, as shown in an enlarged view in Figure 6, each internal tooth 55c is made up of a shaft member 551 and an outer ball bearing 552. The shaft member 551 has a large-diameter base portion 551a and a small-diameter shaft portion 551b. The outer ball bearing 552 is fitted onto the shaft portion 551b. The internal teeth 55c may also be made up of pins.

[0076] The tooth support portion 55b has 24 embedded holes 55d formed at equal intervals in the circumferential direction. The outer peripheral edge portion 55a has arc-shaped recesses 55e formed to receive a portion of the internal teeth 55c, corresponding to these embedded holes 55d. By press-fitting the base portion 551a into the embedded holes 55d, each internal tooth 55c is supported by the fixing ring 55 in a rotatable manner.

[0077] By using ball bearings for the internal teeth 55c, frictional resistance during partial contact with the engaging teeth 54a can be significantly reduced. This is particularly effective for the high-speed rotating cycloidal speed increaser 50. It can also improve power generation efficiency.

[0078] The first spacer ring 56 is a thin, annular member. With the outer ball bearing 552 inserted into the shaft portion 551b of each internal tooth 55c, the outer circumference of the first spacer ring 56 is assembled to the input side of the outer peripheral edge 55a of the fixing ring 55.

[0079] To increase the power generation efficiency of the cycloidal speed increaser 50, the outer circumference of the cycloidal disc 54 can be clamped between the first spacer ring 56 and the second spacer ring 53 via a pair of thrust bearings 63, 63. This allows the cycloidal disc 54 to rotate stably without tilting, thereby increasing power generation efficiency.

[0080] The outer circumference of the cycloidal disc 54 is supported so as to be able to rotate freely and slide radially. Furthermore, if sufficient power generation efficiency can be obtained for the intended use, the thrust bearing 63 may not be used. Also, the size of the thrust bearing 63 can be appropriately selected according to the size of the cycloidal speed increaser 50.

[0081] Furthermore, the first spacer ring 56 is provided with ring-shaped projections 56a. These ring-shaped projections 56a prevent the outer ball bearing 552 from coming off.

[0082] The cover 58 is a disc-shaped member centered on the base shaft J1. The support cylinder portion 70 is assembled to the opening in the central part of the cover 58. Multiple (8) shaft fixing holes 58a are formed on the outer circumference of the cover 58, which is spaced apart from the first spacer ring 56. These shaft fixing holes 58a are arranged at equal intervals in the circumferential direction.

[0083] An input pinion 22 is rotatably supported in each of these shaft-locking holes 58a. Specifically, a pinion shaft 22a is supported in the shaft-locking hole 58a via a ball bearing. The input pinion 22 is attached to the tip of the pinion shaft 22a.

[0084] The input-side internal teeth 21 are configured to contact and mesh with these input-side pinions 22 from the radially outer side of the cycloidal speed increaser 50.

[0085] A cylindrical input-side coaxial boss portion 58b is formed in the center of the cover 58. An input-side ball bearing 65 for pivot support is fitted inside the input-side coaxial boss portion 58b. The first rotating body 57 is rotatably pivotally supported in the cover 58 via the input-side ball bearing 65.

[0086] The first rotating body 57 is a disc-shaped member that rotates around the base axis J1. A cylindrical first boss portion 57a ​​is formed in the central part of the first rotating body 57, centered on the base axis J1. The input side ball bearing 65 is fitted onto this first boss portion 57a ​​with the support cylinder portion 70 inserted through it.

[0087] The outer circumference of the first rotating body 57 can be clamped between the cover 58 and the first spacer ring 56 via a pair of thrust bearings 64, 64, similar to the outer circumference of the second rotating body 52. ​​This allows the first rotating body 57 to rotate stably without tilting, thereby increasing power generation efficiency.

[0088] Furthermore, if sufficient power generation efficiency can be obtained for the intended use, the thrust bearing 64 may not be used. Also, the size of the thrust bearing 64 can be appropriately selected according to the size of the cycloidal speed increaser 50.

[0089] As shown in Figure 3A, by using a pair of thrust bearings 63, 63 or thrust bearings 64, 64 arranged on the outer circumference of the first rotating body 57, the second rotating body 52, and the cycloidal disc 54, stable rotation can be achieved without tilting of the first rotating body 57, the cycloidal disc 54, and the second rotating body 52, thereby increasing the power generation efficiency of the cycloidal speed increaser 50.

[0090] Annular input-side external teeth 57c are provided on the outer periphery of the first rotating body 57. The input-side pinion 22 meshes with the outer periphery of these input-side external teeth 57c. Therefore, the rotational force of the hub body 3 is transmitted to the first rotating body 57 via the input-side internal teeth 21, the input-side pinion 22, and the input-side external teeth 57c.

[0091] On the surface of the first rotating body 57 facing the cycloidal disk 54, a plurality of engagement portions 57b (eight in this embodiment) are provided, corresponding to the engagement holes 54b of the cycloidal disk 54. Unlike the engagement holes 54b, these engagement portions 57b are arranged at equal intervals along the circumference centered on the base axis J1.

[0092] Furthermore, these engaging portions 57b are configured to be located within the engaging holes 54b. As a result, as shown in Figure 4, these engaging portions 57b are configured to partially contact the inner circumferential surface of the engaging holes 54b of the cycloidal disk 54 and transmit rotational force.

[0093] In this embodiment, these engaging portions 57b are constructed with ball bearings, similar to the internal teeth 55c. Specifically, as shown in Figure 7, each engaging portion 57b is composed of a second shaft member 571 and an inner ball bearing 572. The second shaft member 571 has a large-diameter second base portion 571a, a small-diameter second shaft portion 571b, and a press-fit ring 571c. The inner ball bearing 572 is fitted onto the second shaft portion 571b, and the press-fit ring 571c prevents the inner ball bearing 572 from coming off. The engaging portions 57b may also be constructed with pins.

[0094] By using ball bearings for the engaging portion 57b in addition to the internal teeth 55c, frictional resistance during partial contact with the engaging hole 54b can be significantly reduced. This is particularly effective for the high-speed rotating cycloidal speed increaser 50. It can improve power generation efficiency.

[0095] (Slotless Brushless Motor) Figure 8 shows the structure of the brushless motor 80. The brushless motor 80 consists of an input shaft 81, a housing 82, a rotor 83, a stator 84, an input member 85, and so on. As described above, the brushless motor 80 is a brushless motor that does not have brushes and electronically controls the mechanical rectification function.

[0096] The housing 82 has a cylindrical main case 82a with a sealed front end and a disc-shaped end plate 82b that closes the rear end of the main case 82a. A small-diameter mounting hole is formed in the rear end wall of the housing 82, passing through its center.

[0097] As described above, the front end wall of the housing 82 is provided with a boss portion 82c for attachment to the cycloidal speed increaser 50. A large-diameter shaft support hole 82d is formed in the center of the boss portion 82c, penetrating the wall surface.

[0098] Inside the housing 82 is a short, cylindrical bearing house 86, one end of which is attached to the support hole 82d. Each end of the bearing house 86 is fitted with an annular, oil-less metal 87 that functions as a bearing.

[0099] The input shaft 81 is rotatably supported by these oil-less metals 87, with a pair of liners preventing it from coming loose. The input shaft 81 is cylindrical, and an insertion hole 81a is formed in its center, which is larger in diameter than the support cylinder portion 70 and extends in the direction of the base axis J1.

[0100] The support cylinder portion 70 is inserted into the insertion hole 81a together with the hub shaft 2, with a gap between it and the inner circumferential surface of the insertion hole 81a. As a result, the input shaft 81 is rotatable while being arranged coaxially with the non-rotatable support cylinder portion 70 and the like.

[0101] Furthermore, since the main body of the brushless motor 80 is independent of the support cylinder 70 and other components, it can be easily removed. Therefore, it is easy to replace. It can also accommodate changes in the shape of the support cylinder 70 and other components.

[0102] The front end of the input shaft 81 protrudes forward from the bearing house 86 (housing 82). This front end is press-fitted into the input member 85, thereby integrating it with the input member 85. As a result, the input shaft 81 is coaxially connected to the second rotating body 52 of the cycloidal speed increaser 50.

[0103] The rear end portion of the input shaft 81 is located inside the housing 82, protruding from the bearing house 86. A bottomed cylindrical rotor yoke 83a is coaxially mounted to this protruding portion, with the bearing house 86 enclosing it. Specifically, a mounting boss is provided in the center of the rear end face of the rotor yoke 83a. The protruding portion of the input shaft 81 is press-fitted into this mounting boss. A cylindrical magnet 83b, which constitutes a magnetic pole, is mounted on the outside of the rotor yoke 83a.

[0104] These rotor yoke 83a and magnet 83b constitute the rotor 83. In other words, the rotor 83 does not include a core made of laminated steel plates. Cogging torque is hardly generated.

[0105] A cylindrical stator 84 is positioned inside the housing 82, along the inner circumferential surface of the housing 82. The stator 84 has a stator core 84a made of laminated steel plates and a plurality of coils 84b that constitute the magnetic poles. In the case of this brushless motor 80, the plurality of coils 84b are arranged along the inner circumferential surface of the housing 82.

[0106] A circuit board 88 is mounted inside the end plate 82b. The electrical wiring forming the coil 84b is connected to the circuit board 88. A Hall IC 88a for detecting the rotation of the rotor 83 is installed on the circuit board 88. The circuit board 88 also has terminals 88b to which external electrical wiring is connected.

[0107] The stator 84 is positioned around the rotor 83 with a small air gap in between. This brushless motor 80 is an inner rotor type. When the rotor 83, which is integrated with the input shaft 81, rotates, the magnetic field changes due to the magnetic force of the magnet 83b.

[0108] As a result of this action, current flows through the coil 84b of the stator 84. This current is rectified by the circuit board 88 and then output from the brushless motor 80 through terminal 88b. In other words, the brushless motor 80 generates electricity when rotational force is input to it.

[0109] The rotation of the input shaft 81 is accelerated by the cycloidal speed increaser 50, thus increasing the amount of power generated. Since the rotor 83 is coreless, cogging torque that would have a practical impact is not generated. Therefore, smooth high rotation can be achieved. It is also lightweight and has excellent responsiveness. Therefore, the bicycle can be ridden comfortably even at night.

[0110] <Second Embodiment> As another preferred application example of the disclosed technology, Figure 9 illustrates a micro-generator 200 (corresponding to a small generator) that is assembled into piping. Figure 10 shows the main parts of the micro-generator 200.

[0111] Furthermore, the basic configuration of the micro-generator 200 (speed control member, power generation member, etc.) is the same as that of the power generation unit 6 of the first embodiment described above. Therefore, the explanation of the configuration, which is the same as that of the first embodiment, will be simplified or omitted.

[0112] The micro-generator 200 generates electricity from the flow of fluid through a pipe. Therefore, the micro-generator 200 can be installed and used in any pipe through which fluid flows. For example, in water-related facilities such as washrooms, kitchens, and bathrooms, it can be installed in pipes through which water or hot water flows. In air conditioning or gas facilities, it can be installed in pipes through which air or gas flows.

[0113] The micro-generator 200 consists of a cycloidal speed increaser 50 and a brushless motor 80, along with an impeller 230, a main body case 210, and the like. The main body case 210 has its central portion attached to a support shaft 220 that extends axially. Inside the main body case 210, the power generation unit 6 and the cycloidal speed increaser 50 are arranged coaxially.

[0114] An impeller 230 is assembled to the housing side of the cycloidal speed increaser 50 in the main body case 210. The impeller 230 is mounted coaxially with the main body case 210 via ball bearings 231 such that its fins are located on the outside of the main body case 210. As a result, the impeller 230 is pivotally supported by the main body case 210 in a rotatable state.

[0115] A rotational force transmission mechanism 232 is provided on the radially inner side of the impeller 230, similar to a hub dynamo, to connect the impeller 230 and the cycloidal speed increaser 50. For example, the rotational force transmission mechanism 232 may utilize the meshing of input-side internal teeth and input-side pinion. The rotation of the impeller 230 is transmitted to the cycloidal speed increaser 50 through this rotational force transmission mechanism 232.

[0116] As shown by arrow F in Figure 9, when water flows, the impeller 230 rotates as indicated by arrow R, pushed by the flow.

[0117] As a result, when the impeller 230 rotates, the rotational force of the impeller 230 is transmitted to the cycloidal speed increaser 50 via the rotational force transmission mechanism 232. Then, the rotational force increased by the cycloidal speed increaser 50 is transmitted to the brushless motor 80, generating electricity. This allows for compact and efficient power generation.

[0118] Furthermore, the disclosed technology is not limited to the embodiments described above, but also encompasses various other configurations.

[0119] In other words, as mentioned above, the disclosed technology is suitable for bicycle hub dynamos and plumbing equipment, but it can also be applied to other applications. For example, it can be applied to wind power generation, hydroelectric power generation, and portable small generators used in disaster relief and camping.

[0120] The structure of the hub dynamo 1 is just one example. The structure of the hub 1, which forms its base, can be modified according to the specifications. The same applies to the micro-generator 200. The structure of the cycloidal speed increaser 50 is also just one example. For example, the gear ratio can be modified as appropriate according to the specifications.

[0121] The input-side rotational force transmission mechanism 20 described above is one example. It may also be configured to transmit force using frictional resistance. In addition to these, it may also be constructed using belts, magnetic gears, etc.

[0122] 1 Hub (hub dynamo) 2 Hub shaft (base shaft) 3 Hub body (rotating member) 5 Hub bearing 6 Power generation unit (small generator) 20 Input side rotational force transmission mechanism 21 Input side internal teeth 22 Input side pinion 50 Cycloid speed increaser (cycloidal transmission, transmission member) 51 Support base 52 Second rotating body 52a Coaxial boss part 52b Eccentric boss part 52c Connecting hole 53 Second spacer ring 54 Cycloid disc 54a Engaging teeth 54b Engaging hole 55 Fixing ring 55a Outer peripheral edge part 55b Tooth support part 55c Internal teeth 55d Embedded hole 55e Recessed part 56 First spacer ring 56a Ring-shaped projection 57 First rotating body 57a First boss part 57b Engaging part 57c Input side external teeth 58 Cover 59 Fixing bolt 60 Output side ball bearing 61 Intermediate ball bearing 63 Thrust bearing 64 Thrust bearing 65 Input side ball bearing 66 Input shaft 70 Support cylinder section 75 Support flange 80 Slotless brushless motor (power generation component) 81 Input shaft 81a Through hole 82 Housing 83 Rotor 83a Rotor yoke 83b Magnet 84 Stator 84a Stator core 84b Coil 85 Input component 86 Bearing house 87 Oil-less metal 88 Circuit board 100 Wheel 101 Tire 102 Rim 103 Spoke 104 Fork 200 Micro generator (small generator) 210 Main case 220 Support shaft (base shaft) 230 Impeller 231 Ball bearing 232 Rotational force transmission mechanism J1 Base shaft J2 eccentric shaft

Claims

1. A small generator comprising: a rotating member that rotates about a base axis by the action of an external force; a power generation member provided coaxially with the rotating member and converting the rotational force of the rotating member into electricity; and a speed change member provided coaxially with the rotating member and the power generation member and interposed between the rotating member and the power generation member, wherein a cycloidal transmission is used in the speed change member to increase the speed of the rotation of the rotating member and transmit it to the power generation member.

2. A small generator according to claim 1, wherein the speed change member includes a thrust bearing that rotates around the base shaft.

3. A small generator according to claim 2, wherein the speed change member comprises: a first rotating body that rotates around the base axis; a second rotating body that rotates around the base axis at increased speed; a cycloidal disc disposed between the first rotating body and the second rotating body; and a fixed ring disposed on the outer circumference of the cycloidal disc in a non-rotatable state, wherein the second rotating body has an eccentric boss portion that rotatably supports the cycloidal disc about an eccentric axis that is eccentric with respect to the base axis; the cycloidal disc has a plurality of engaging teeth formed at equal intervals along its outer circumference and a plurality of engaging holes that open on its surface and are formed at equal intervals along a circumference centered on the eccentric axis; the first rotating body has a plurality of engaging portions formed at equal intervals along a circumference centered on the base axis and partially in contact with the inner surfaces of the plurality of engaging holes; and the fixed ring has a plurality of internal teeth that partially mesh with the plurality of engaging teeth, wherein the internal teeth are made of bearings.

4. A small generator according to claim 1, wherein the speed change member is supported on a base shaft that extends coaxially with the base shaft.

5. A small generator according to claim 4, wherein the power generation member comprises: an input shaft that rotates about a base axis; a rotor including a magnet and fixed around the input shaft; and a stator including a coil and a core and arranged around the rotor with an air gap between them, wherein the input shaft has a through hole formed therein that extends in the direction of the base axis, and the base shaft is inserted into the through hole with a gap between it and the inner circumferential surface of the through hole.

6. A small generator according to any one of claims 1 to 5, wherein the small generator is attached to a hub dynamo that constitutes a bicycle wheel and generates electricity by the rotation of the wheel.

7. A small generator according to any one of claims 1 to 5, wherein the small generator generates electricity by the flow of a fluid.

8. A small generator comprising: a rotating member that rotates about a base axis by the action of an external force; a power generation member provided coaxially with the rotating member and converting the rotational force of the rotating member into electricity; and a speed change member provided coaxially with the rotating member and the power generation member and interposed between the rotating member and the power generation member, wherein the power generation member comprises: an input shaft that rotates about the base axis; a rotor including a magnet and fixed around the input shaft; and a stator including a coil and a core and arranged around the rotor with an air gap, wherein the input shaft has an insertion hole formed therein that extends in the direction of the base axis.

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