generator

Abstract

To provide a generator with good power generation efficiency.SOLUTION: A generator (1) includes: a holder (2) having a storage space; a rotary shaft (3) rotatably supported by the holder and having at least one end exposed outside the holder; a rotary magnet (4) arranged in the storage space of the holder and fixed to the rotary shaft; a non-magnetic tubular member (7) arranged with one end close to the rotary magnet and with the other end away from the rotary magnet, and is held by the holder; a coil (8) arranged on an outer circumference of the tubular member; and a magnetic core (6) made of a soft magnetic material arranged in the tubular member and repeatedly reversing a direction of magnetism upon receiving a magnetic force from the rotary magnet.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a generator. [Background technology]

[0002] One example of technology using a generator is disclosed in Japanese Patent Application Laid-Open No. 2018-191417 (Patent Document 1). Patent Document 1 discloses a vibration dynamo power generator that includes an external magnet fixed to the pedal of a bicycle and a current generator that is fixed to the body of the bicycle and houses a spherical magnet inside. In the vibration dynamo device of Patent Document 1, the current generator is positioned on the rotational orbit of the external magnet, so that simply rotating the pedal vibrates the spherical magnet inside the current generator, generating electricity. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-191417 Summary of the Invention [Problem to be solved by the invention]

[0004] The vibration dynamo device disclosed in Patent Document 1 generates electricity by vibrating a spherical magnet inside a current generator due to the orbital motion of an external magnet around the rotation axis of the pedal. For this reason, the amount of power obtained is relatively small compared to the effort required to rotate the pedal, and there is a need to improve power generation efficiency.

[0005] An object of the present invention is to provide a generator with high power generation efficiency. [Means for solving the problem]

[0006] The generator according to one embodiment of the present invention comprises a holder having a storage space, a rotating shaft supported by the holder so as to be freely rotatable, with at least one end exposed to the outside of the holder, a rotating magnet arranged within the storage space of the holder and fixed to the rotating shaft, a non-magnetic cylindrical member held by the holder with one end close to the rotating magnet and the other end positioned away from the rotating magnet, a coil arranged on the outer periphery of the cylindrical member, and a magnetic core made of soft magnetic material arranged within the cylindrical member and which repeatedly reverses its magnetic direction when subjected to magnetic force from the rotating magnet.

[0007] Preferably, the magnetic core further comprises a yoke made of a soft magnetic material that abuts against at least one end or the other end of the magnetic core and is held by the holder.

[0008] Preferably, the current generating section including the cylindrical member, the coil, and the magnetic core includes a first current generating section and a second current generating section provided at positions rotationally symmetrical about the rotation axis.

[0009] A generator according to another aspect of the present invention comprises a holder having a storage space, a rotating shaft rotatably supported by the holder and having at least one end exposed to the outside of the holder, a rotating magnet arranged within the storage space of the holder and fixed to the rotating shaft, a non-magnetic cylindrical member having one end and the other end, arranged so that its outer surface is close to the rotating magnet and held by the holder, a coil arranged on the outer periphery of the cylindrical member, a magnetic core made of soft magnetic material arranged within the cylindrical member and which repeatedly reverses its magnetic direction in response to magnetic force from the rotating magnet, and a yoke made of soft magnetic material abutting one end and the other end of the magnetic core and held by the holder.

[0010] Preferably, the outer circumferential surface of the coil wound around the cylindrical member is close to the rotation axis, and the central axis of the cylindrical member extends in a direction perpendicular to the rotation axis at a position that does not intersect with the rotation axis.

[0011] Preferably, the current generating unit including the cylindrical member, the coil, the magnetic core, and the yoke includes a first current generating unit and a second current generating unit arranged in rotationally symmetric positions around the rotation axis.

[0012] Preferably, the rotary magnet is a cylindrical magnet that is magnetized with two poles in the circumferential direction.

[0013] Preferably, the rotating shaft has a pinion at one end portion exposed from the holder. [Effects of the Invention]

[0014] According to the generator of the present invention, power generation efficiency can be improved by utilizing a rotating magnet that rotates around a rotation axis and a magnetic core made of soft magnetic material that repeatedly reverses its magnetic direction in response to the magnetic force from the rotating magnet. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a perspective view of a generator according to a first embodiment of the present invention. [Figure 2] 1 is a cross-sectional view of a generator according to a first embodiment of the present invention. [Figure 3] FIG. 10 is a perspective view of a generator according to a second embodiment of the present invention. [Figure 4] FIG. 10 is a cross-sectional view of a generator according to a second embodiment of the present invention. [Figure 5] FIG. 10 is a perspective view of a generator according to a third embodiment of the present invention. [Figure 6] FIG. 10 is a cross-sectional view of a generator according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the accompanying drawings, in which the same or corresponding parts are designated by the same reference numerals and will not be described repeatedly.

[0017] <First Embodiment> A generator 1 according to one embodiment of the present invention will be described with reference to Figures 1 and 2. In Figure 2, the direction indicated by arrow A1 is referred to as the left-right direction, and the direction indicated by arrow A2 is referred to as the front-rear direction.

[0018] The generator 1 comprises a holder 2 having a storage space 21, a rotating shaft 3 rotatably supported by the holder 2 and having at least one end exposed to the outside of the holder 2, a rotating magnet 4 arranged within the storage space 21 of the holder 2 and fixed to the rotating shaft 3, a non-magnetic tubular member 7 held by the holder 2 and arranged so that one end is close to the rotating magnet 4 and the other end is away from the rotating magnet 4, a coil 8 arranged on the outer periphery of the tubular member 7, and a magnetic core 6 made of soft magnetic material arranged within the tubular member 7 and which repeatedly reverses its magnetic direction when it receives a magnetic force from the rotating magnet 4.

[0019] The holder 2 has a storage space 21 that houses the rotary magnet 4 and a through-hole 22 through which the rotary shaft 3 is inserted in the vertical direction. In this embodiment, the storage space 21 further has grooves 23 on the left and right sides for accommodating the cylindrical member 7.

[0020] The holder 2 is made of a non-magnetic material. A non-magnetic material is a substance that is not ferromagnetic, and includes paramagnetic materials, diamagnetic materials, and antiferromagnetic materials. Examples of non-magnetic materials include metals such as aluminum, and synthetic resins such as plastic. In this embodiment, the holder 2 is preferably made of synthetic resin.

[0021] The rotating shaft 3 is rotatably supported in the through-hole 22 of the holder 2. The rotating shaft 3 is provided so as to be rotatable around a rotation axis O along the extending direction of the rotating shaft 3. The rotating shaft 3 extends through the through-hole 22 of the holder 2 and the entire storage space 21. The rotating shaft 3 has a pinion 31 on one end portion exposed from the holder 2.

[0022] A rotary magnet 4 is fixed to the portion of the rotary shaft 3 inserted inside the holder 2 that is located in the storage space 21. The rotary magnet 4 is fixed to the rotary shaft 3 by, for example, adhesive bonding or press fitting, and rotates together with the rotary shaft 3 about the rotation axis O. In this embodiment, the rotary magnet 4 is a cylindrical magnet.

[0023] The magnet used as the rotating magnet 4 is a permanent magnet. The rotating magnet 4 of this embodiment is magnetized with two poles in the circumferential direction, but the number of poles of the rotating magnet 4 is not particularly limited as long as it has two or more poles. The "circumferential direction" refers to the circumferential direction extending along the outer periphery of the rotating magnet 4. The rotating magnet 4 of this embodiment is a cylindrical magnet with a ring shape in a plan cross section, but its shape and number are not limited. For example, two or more permanent magnets may be fixed to the rotating shaft 3, so that the polarity alternates in the circumferential direction. Since at least the outer periphery of the rotating magnet 4 needs to be magnetized, it may be magnetized on one side or both sides. The material of the rotating magnet 4 is not particularly limited, but it is preferable to use an Nd-Fe-B sintered magnet (neodymium magnet) from the viewpoint of exhibiting high magnetic force.

[0024] Washers 32 are arranged to face both vertical end faces of the rotary magnet 4. Washer 32 is a ring-shaped plate material, and the rotary shaft 3 is inserted through its center. In other words, washer 32 is arranged to be rotatable around the rotation axis O. Washer 32 is a flat washer made of, for example, stainless steel. This makes it possible to prevent or suppress wear on holder 2 and rotary magnet 4 caused by rotation of the rotary shaft 3.

[0025] The configuration including the cylindrical member 7, coil 8, and magnetic core 6 generates current through electromagnetic induction. Therefore, these components can be collectively referred to as the "current generating unit 5." The current generating unit 5 includes a first current generating unit 51 and a second current generating unit 52, which are arranged in rotationally symmetric positions around the rotation axis 3. The first current generating unit 51 includes a first cylindrical member 71, a first coil 81 arranged on the outer periphery of the first cylindrical member 71, and a first magnetic core 61 arranged within the cylindrical member 71 of the first current generating unit 51. The second current generating unit 52 includes a second cylindrical member 72, a second coil 82 arranged on the outer periphery of the second cylindrical member 72, and a second magnetic core 62 arranged within the cylindrical member 72 of the second current generating unit 52. In other words, the first and second current generating units 51 and 52 have similar configurations. In the following description, when there is no need to distinguish between the first current generating unit 51 and the second current generating unit 52, they will be referred to as the "current generating unit 5." Similarly, the first magnetic core 61 and the second magnetic core 62 will be referred to as the "magnetic core 6," the first cylindrical member 71 and the second cylindrical member 72 will be referred to as the "cylindrical member 7," and the first coil 81 and the second coil 82 will be referred to as the "coil 8."

[0026] The cylindrical member 7 is, for example, a cylindrical rod with a hollow interior, and at least one end or the other end is fixed to the holder 2. The cylindrical member 7 is made of a non-magnetic material. In this embodiment, it is made of a synthetic resin such as plastic for ease of formation. The cylindrical member 7 in this embodiment extends in the left-right direction (the direction of arrow A1) as shown in FIG. 2.

[0027] A coil 8 is wound around the outer periphery of this cylindrical member 7. Therefore, the cylindrical member 7 also serves as a bobbin for the coil 8. In this embodiment, the coil 8 is provided on a portion of the outer periphery of the cylindrical member 7, but it may also be provided on the entire periphery of the cylindrical member 7. The coil 8 is, for example, a solenoid coil.

[0028] The magnetic core 6 is a long rod-like member housed inside the cylindrical member 7. The long rod-like member may be a single member or a series of multiple members that are long as long as it is long overall. From the viewpoint of increasing the electromotive force, the magnetic core 6 is preferably housed inside the cylindrical member 7 from one end to the other end.

[0029] The magnetic core 6 is made of a soft magnetic material to facilitate switching its magnetism, and changes to a magnetic body by bringing a magnet close to at least one end or the other end. The magnetic core 6 can be made of any soft magnetic material, such as iron, stainless steel (SUS), high-speed steel (SKH), or ferrite. This means that if the device is designed to generate electricity by rotating the pinion 31 when a switch on a wireless remote control is pressed, for example, electricity can be generated and transmitted wirelessly instantly by simply pressing the switch, reducing the time lag.

[0030] In this embodiment, magnetic core 6 is arranged with one end facing the outer circumferential surface of rotary magnet 4, separated by holder 2. As a result, magnetic core 6 is magnetized by the magnetic force of rotary magnet 4. Magnetic core 6 receives the magnetic force from rotary magnet 4 and repeatedly reverses its magnetic direction, thereby generating a current in coil 8. In other words, the magnetic field lines generated from magnetic core 6 intersect (are perpendicular to) coil 8, generating an AC current in coil 8.

[0031] As shown by the dashed dotted line in FIG. 1, the generator 1 further includes a yoke 9 made of soft magnetic material that abuts against at least one end or the other end of the magnetic core 6 and is held by the holder 2. This further reduces leakage magnetic flux and increases the induced electromotive force, thereby increasing the amount of power generated by the generator 1. The yoke is soft iron that amplifies the attractive force of the magnet, and it is sufficient that it contains iron and includes a soft magnetic material. From the perspective of further increasing the amount of power generated, it is preferable that the yoke 9 abuts against at least one end or the other end of the magnetic core 6.

[0032] In this embodiment, the yoke 9 is held on the outer peripheral surface of the holder 2 around the rotation axis 3, and the current generating unit 5 is not visible from the outside. This prevents problems caused by foreign matter entering the current generating unit 5. Furthermore, if the other end of the magnetic core 6 and the yoke 9 are in contact with each other, the magnetism of the yoke 9 and the magnetic core 6 can be switched together, thereby increasing the induced electromotive force.

[0033] In this embodiment, the outer diameter of magnetic core 6 and the inner diameter (diameter of the hollow shape) of cylindrical member 7 are approximately the same. Since magnetic core 6 arranged inside cylindrical member 7 is attracted by the attractive force from rotary magnet 4, it is preferable to place a part of holder 2 between magnetic core 6 and rotary magnet 4. This holds magnetic core 6 within cylindrical member 7, preventing magnetic core 6 from sticking to rotary magnet 4.

[0034] One end of the coil 8 of the current generating unit 5 is connected to a rectifying unit (not shown), and the current rectified by the rectifying unit (not shown) is transmitted to an external member (not shown). This allows the external member to be activated by the current generated by the current generating unit 5. Note that the AC current generated in the coil 8 may be transmitted to the external member without being rectified.

[0035] Furthermore, in the generator 1 of this embodiment, the rotating magnet 4 and the magnetic core 6 are always positioned close to each other, which reduces leakage magnetic flux. The generator 1 can ensure sufficient power generation even with small movements because it can effectively utilize the magnetic forces generated by both the rotating magnet 4 and the magnetic core 6. In other words, the generator 1 of this embodiment is characterized by its high power generation efficiency relative to movement.

[0036] As described above, according to this embodiment, if the rotating shaft 3 and the rotating magnet 4 are considered to be a "rotating body," then the holder 2, the cylindrical member 7, the coil 8, and the magnetic core 6 can be considered to be a "fixed body." In other words, even without rotating, swinging, or vibrating the cylindrical member 7 itself, a current can be easily generated from the magnetic core 6 by the magnetic force of the rotating rotating magnet 4.

[0037] As a result, this embodiment can generate current efficiently with low torque. In other words, it is possible to improve the power generation efficiency of the current generating unit 5. Furthermore, unlike Patent Document 1, there is no need for a spherical magnet to vibrate inside a cylindrical member, and no member for vibrating the spherical magnet is required, so the generator 1 can have a simple and compact structure.

[0038] If the generator 1 of this embodiment is designed to generate enough power to operate a wireless remote control when the rotor rotates by, for example, 180°, by connecting the pinion 31 to the input section of the wireless remote control and magnetizing the outer periphery of the rotating magnet 4 with two poles, the magnetic direction of the magnetic core 6 will reverse once during the 180° rotation of the rotor. In other words, by simply pressing the input section of the wireless remote control once, the magnetic direction of the magnetic core 6 made of soft magnetic material will reverse, providing a pleasant clicking sensation. The "clicking sensation" refers to the sound or response felt when a switch is pressed. In other words, the generator 1 of this embodiment can be suitably used as a generator for small devices such as wireless remote controls.

[0039] The generator 1 of this embodiment employs an inexpensive electromagnetic induction system as a generator. Furthermore, by using a magnetic core 6 made of a soft magnetic material to cause electromagnetic induction, it is possible to further reduce costs.

[0040] <Embodiment 2> A generator 1A according to a second embodiment of the present invention will be described with reference to Figures 3 and 4. Figure 3 is a perspective view of the generator 1A according to this embodiment, and Figure 4 is a cross-sectional view of the generator 1A according to this embodiment. The generator 1A according to the second embodiment basically has the same configuration as the generator 1 according to the first embodiment, but differs in the arrangement of the yoke 9A and the current generating unit 5A, as shown in Figure 3. In Figure 3, the direction indicated by the arrow A3 is referred to as the up-down direction.

[0041] 3, generator 1A in this embodiment is provided with first current generating unit 51A and second current generating unit 52A at rotationally symmetric positions about rotation axis 3. Generator 1A is provided with yoke 9A that abuts against one end or the other end of first current generating unit 51A and second current generating unit 52A and is held by holder 2A.

[0042] The yoke 9A is held by the holder 2A so as to cover the outer peripheral surface of the holder 2A around the rotation axis 3. Unlike the generator 1, the generator 1A of this embodiment does not have the outer peripheral surface of the coil 8A covered by the yoke 9A.

[0043] In the generator 1A of this embodiment, as the rotating shaft 3 and rotating magnet 4A rotate, the magnetic force from the rotating magnet 4A causes the magnetic core 6A to repeatedly reverse its magnetic orientation. In other words, the generator 1A of this embodiment generates power by simply switching the magnetic orientation of the magnetic core 6A, which generates electromagnetic induction in the current generating unit 5A. Furthermore, unlike the vibration dynamo device of Patent Document 1, the generator 1A does not require a spherical magnet placed inside a cylindrical member to vibrate, nor does it require any vibration components. In other words, the relative positions of the rotating magnet 4 and magnetic core 6A of the generator 1A do not change even during motion (power generation). This allows the generator 1A to be made smaller.

[0044] Third Embodiment A generator 1B according to a third embodiment of the present invention will be described with reference to Figures 5 and 6. Figure 5 is a perspective view of the generator 1B according to this embodiment, and Figure 6 is a cross-sectional view of the generator 1B according to this embodiment. The generator 1B according to the third embodiment basically has the same configuration as the generator 1 according to the first embodiment, but differs in the arrangement of the current generating unit 5B, as shown in Figure 5.

[0045] As shown in Figures 5 and 6, generator 1B in this embodiment includes holder 2B having storage space 21B, rotating shaft 3 rotatably supported by holder 2B and at least one end of which is exposed to the outside of holder 2B, rotating magnet 4B arranged within storage space 21B of holder 2B and fixed to rotating shaft 3, non-magnetic cylindrical member 7B having one end and the other end and arranged so that its outer circumferential surface is close to rotating magnet 4B and held by holder 2B, coil 8B arranged on the outer periphery of cylindrical member 7B, magnetic core 6B made of soft magnetic material arranged within cylindrical member 7B and repeatedly reversing its magnetic direction in response to magnetic force from rotating magnet 4B, and yoke 9B made of soft magnetic material abutting one end and the other end of magnetic core 6B and held by holder 2B.

[0046] Unlike the generators 1 and 1A of the first and second embodiments, the generator 1B of the third embodiment has an end of the magnetic core 6B that does not face the outer peripheral surface of the rotary magnet 4B. In other words, at least a portion of the outer peripheral surface 83B of the coil 8B wound around the cylindrical member 7B is close to the rotation axis 3. Furthermore, the central axis of the cylindrical member 7B of the present embodiment extends in a direction perpendicular to the rotation axis 3 at a position that does not intersect with the rotation axis 3. Due to this configuration, it is difficult to bring the magnetic core 6B and the rotary magnet 4B sufficiently close to each other in the generator 1B, and the rotary magnet 4B makes almost no contribution to the induced electromotive force generated in the magnetic core 6B.

[0047] However, generator 1B is configured such that yoke 9B and rotary magnet 4B are in close proximity to each other. Yoke 9B is magnetized by the magnetic force from rotary magnet 4B, and magnetizes magnetic core 6B, which is in contact with yoke 9B. In other words, in generator 1B, rotary magnet 4B and yoke 9B are in close proximity to each other and are in contact with magnetic core 6B, so that the magnetism of yoke 9B switches as rotary magnet 4B rotates, reversing the polarity of magnetic core 6B, thereby generating electricity.

[0048] The configuration including the cylindrical member 7B, coil 8B, magnetic core 6B, and yoke 9B generates current through electromagnetic induction. Therefore, these components can be collectively referred to as the "current generating unit 5B." The current generating unit 5B includes a first current generating unit 51B and a second current generating unit 52B, which are arranged in rotationally symmetric positions around the rotation axis 3. In other words, the current generating unit 5B of the generator 1B is larger than the current generating units 5 and 5A of the generators 1 and 1A, and therefore generates a larger induced electromotive force when the magnetic direction is reversed, thereby increasing the amount of power generation.

[0049] The yoke 9B is provided on at least the upper and lower surfaces of the holder 2B. The yoke 9B may be arranged in any position so as to be able to receive the magnetic force of the rotary magnet 4B and magnetize the magnetic core 6B. Specifically, the yoke 9B is provided so as to cover the upper (lower) surface of the holder 2B at a position close to the rotary magnet 4B and at a position abutting one end (other end) of the magnetic core 6B. In other words, the pair of yokes 9B is provided so as to sandwich the magnetic core 6B and the rotary magnet 4B from above and below. The yoke 9B may be, for example, a single plate-shaped member or multiple plate-shaped members. This allows the magnetic force of the rotary magnet 4B to be transmitted to the magnetic core 6B.

[0050] In the present embodiment, the central axis of cylindrical member 7B extends in a direction perpendicular to rotation axis 3 at a position that does not intersect with rotation axis 3. However, the central axis of cylindrical member 7B may extend in a direction horizontal to rotation axis 3 as long as yoke 9B is positioned so that it can receive the magnetic force of rotary magnet 4B and magnetize magnetic core 6B.

[0051] Although the current generating units 5, 5A, and 5B in the first, second, and third embodiments are configured to be provided in two units at rotationally symmetric positions around the rotation axis 3, the number is not limited to this. For example, if a sufficient amount of power generation can be ensured to operate an external member, only one current generating unit 5, 5A, and 5B may be provided.

[0052] Furthermore, even if only one current generating unit 5, 5A, 5B is provided, the yoke 9, 9A, 9B is held by the holder 2, 2A, 2B in accordance with the shape of each generator (so as to abut the other end of the magnetic core 6, 6A, 6B).

[0053] Furthermore, although examples have been described in which the generators 1, 1A of the first and second embodiments are provided with the yokes 9, 9A, the generators 1, 1A according to these embodiments have sufficient electromotive force even without the yokes 9, 9A. In other words, the generators 1, 1A do not necessarily have to be provided with the yokes 9, 9A.

[0054] Although the embodiments of the present invention have been described above with reference to the drawings, the present invention is not limited to the illustrated embodiments. Various modifications and variations can be made to the illustrated embodiments within the same scope as the present invention or within an equivalent scope. [Explanation of symbols]

[0055] 1,1A,1B generator, 2,2A,2B holder, 3 rotating shaft, 4 rotating magnet, 5,5A,5B current generating unit, 6,6A,6B magnetic core, 7,7A,7B cylindrical member, 8,8A,8B coil, 9,9A,9B yoke, 31 pinion, 51,51A,51B first current generating unit, 52,52A,52B second current generating unit, 61,61A,61B first magnetic core, 62,62A,62B second magnetic core, 71,71A,71B first cylindrical member, 72,72A,72B second cylindrical member, 81,81A,81B first coil, 82,82A,82B second coil.

Claims

1. a holder having a storage space; a rotating shaft rotatably supported by the holder, at least one end of which is exposed to the outside of the holder; a rotary magnet disposed in the storage space of the holder and fixed to the rotary shaft; a non-magnetic cylindrical member held by the holder, the cylindrical member having one end close to the rotary magnet and the other end spaced apart from the rotary magnet; a coil disposed on the outer periphery of the cylindrical member; a magnetic core made of soft magnetic material that is disposed within the cylindrical member and receives magnetic force from the rotating magnet, and that repeatedly reverses its magnetic direction at a fixed position within the cylindrical member.

2. 2. The generator according to claim 1, further comprising a yoke made of soft magnetic material that abuts against at least one end or the other end of the magnetic core and is held by the holder.

3. a current generating unit including the cylindrical member, the coil, and the magnetic core, The generator according to claim 1 or 2, comprising a first current generating unit and a second current generating unit provided at positions rotationally symmetrical about the rotation axis.

4. a holder having a storage space; a rotating shaft rotatably supported by the holder, at least one end of which is exposed to the outside of the holder; a rotary magnet disposed in the storage space of the holder and fixed to the rotary shaft; a cylindrical member made of a non-magnetic material, having one end and the other end, the outer circumferential surface of which is positioned close to the rotary magnet, and held by the holder; a coil disposed on the outer periphery of the cylindrical member; a magnetic core made of a soft magnetic material that is disposed within the cylindrical member and receives a magnetic force from the rotating magnet, and that repeatedly reverses its magnetic direction at a fixed position within the cylindrical member; a yoke made of soft magnetic material that abuts against one end and the other end of the magnetic core and is held by the holder.

5. 5. The generator according to claim 4, wherein an outer peripheral surface of the coil wound around the tubular member is close to the rotation axis, and a central axis of the tubular member extends in a direction perpendicular to the rotation axis at a position that does not intersect with the rotation axis.

6. a current generating unit including the cylindrical member, the coil, the magnetic core, and the yoke, 6. The generator according to claim 4, further comprising a first current generating section and a second current generating section provided at positions rotationally symmetrical about the rotation axis.

7. 7. The generator according to claim 1, wherein the rotary magnet is a cylindrical magnet that is magnetized with two poles in the circumferential direction.

8. 8. The generator according to claim 1, wherein the rotating shaft has a pinion on one end portion exposed from the holder.

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