Generator

Abstract

Generator (10), the: a runner (40) and a stand (38) which: several magnets (48) arranged at intervals in the circumferential direction such that magnetic poles opposite each other in the circumferential direction have the same polarity; a stator lamination stack (50A, 50B) having coil slot sections (52) arranged on circumferentially opposite sides of the magnets (48); and having an armature coil (60) wound between the coil slot sections (52) so that the magnets (48) are spread circumferentially, wherein the rotor (40) has a rotor lamination stack (46) having several salient pole rotor sections (44) formed at intervals in the circumferential direction, and the stator lamination stack (50A, 50B) has a first salient pole stator section (62A) provided on a first force path section (56A) located next to the coil slot sections (52) in one of the circumferential directions, and a second salient pole stator section (62B) provided on a second force path section (56B) located next to the coil slot sections (52) in the other circumferential direction, wherein the first and the second salient pole stator sections (62A, 62B) are opposite the rotor (40), wherein the first salient pole stator section (62A) extends from the first force path section (56A) and the second salient pole stator section (62B) extends from the second force path section (56B) in the direction of the radially outer side, which is the side opposite the rotor (40), and wherein at least two first salient pole stator sections (62A) are provided per first force path section (56A) and at least two second salient pole stator sections (62B) are provided per second force path section (56B).

Description

[0001] The present invention relates to a generator used for a hub dynamo, etc. of a bicycle.

[0002] In a bicycle hub dynamo, a rotor rotates at approximately the same speed as the wheel, so the rotor's speed tends to be lower compared to a side-mounted dynamo, and the induced electromotive force tends to be insufficient during low-speed riding. Therefore, a low-cost hub dynamo is recommended, which can obtain high-frequency AC power even when the rotor's speed is low.

[0003] For example, Japanese Patent Application Laid-Open No. 2007-49839 A proposes a claw-pole generator. This generator includes a stator and a rotor arranged on the outside of the stator. The rotor includes a plurality of magnets arranged side by side in the circumferential direction; the magnets are configured such that the magnetic poles facing the stator are alternately different magnetic poles in the circumferential direction. The stator includes two stator cores arranged on both sides of the shaft. Each stator core has a plurality of claw portions extending toward one side while approaching each other, and the claw portions of the separate stator cores are arranged alternately in the circumferential direction.The claw portions of each stator core are arranged radially within each magnet and are excited such that the magnet generates polarities that alternate in the circumferential direction. An armature coil is arranged on the stator at a point through which the magnetic flux passes via the claw portions of each stator core.

[0004] In this generator, the relative position of the magnet relative to the claw portions of each stator core changes due to the rotation of the rotor. By switching the polarity of each claw portion along with the above, the direction of the main magnetic flux flowing through the armature coil is reversed, generating an induced electromotive force in the armature coil. Since the AC power obtained at this time will have a frequency proportional to the number of magnet poles, a high-frequency AC power corresponding to the number of magnet poles is easily obtained.

[0005] Other prior art generators are known, for example, from the documents DE 10 2011 121 174 A1, CN 101562384 B, US 6,242,834 B1, WO 2013 / 157 165 A1 and JP 2012 - 182 961 A.

[0006] In recent years, to improve bicycle design, a reduction in the outer diameter of the hub has been required, and so has a reduction in the outer diameter of the hub dynamo. A claw-pole generator is designed so that the claw portions of each stator core, which are excited with different polarities, are arranged alternately in the circumferential direction. Therefore, as the outer diameter of the hub dynamo becomes smaller, the distance between adjacent claw portions becomes too small. As a result, magnetic flux is easily conducted between the claw portions excited with different polarities, and the leakage magnetic flux that does not interlink via the armature coil is slightly increased.Therefore, a claw-pole generator has the problem that the magnetic leakage flux increases when the outer diameter is reduced and it is difficult to obtain a sufficient induced electromotive force.

[0007] The present invention has been made in view of such a problem, and its object is to provide a generator which can easily obtain the high-frequency AC power even when the rotational speed of the rotor is low and whose outer diameter can be suitably reduced.

[0008] The problem is solved with a generator according to claim 1. Advantageous further developments are described in the dependent claims.

[0009] The generator according to an embodiment of the present invention includes a rotor and a stator. The stator includes a plurality of magnets, a stator core, and an armature coil. The magnets are circumferentially spaced so that circumferentially opposite magnetic poles have the same polarity. The stator core includes coil slot portions located on circumferentially opposite sides of the magnets. The armature coil is wound between the coil slot portions so that the magnets are circumferentially straddled. The rotor includes a rotor core having a plurality of salient pole rotor portions formed circumferentially spaced.The stator core includes a first salient pole stator portion provided at a first magnetic path portion located adjacent to the coil slot portions in one of the circumferential directions, and a second salient pole stator portion provided at a second magnetic path portion located adjacent to the coil slot portions in the other circumferential direction. The first and second salient pole stator portions oppose the rotor. The first salient pole stator portion protrudes from the first magnetic path portion toward the radially outer side, and the second salient pole stator portion protrudes from the second magnetic path portion toward the radially outer side, which is the side opposite the rotor.At least two first salient pole stator sections are provided per first force path section, and at least two second salient pole stator sections are provided per second force path section.

[0010] According to the present invention, a generator can be obtained which can easily obtain the high-frequency AC power even when the rotational speed of the rotor is low and whose outer diameter can be appropriately reduced.

[0011] Specific embodiments of the invention will now be described by way of example with reference to the accompanying drawings, in which: Fig. 1 is a partial side view showing a bicycle equipped with the bicycle generator according to the first embodiment; Fig. 2 is a front view showing the configuration of the bicycle hub and its surroundings according to the first embodiment; Fig. 3 is a cross-sectional view of the bicycle generator according to the first embodiment; Fig. 4 is a cross-sectional view showing an armature coil of the bicycle generator according to the first embodiment; Fig. 5 is a view showing the positional relationship of the salient pole rotor portion and the salient pole stator portion according to the first embodiment; Fig. 6 is a view showing a state in which the phase angle of the generator according to the first embodiment is zero; Fig. 7 is a view showing a state in which the phase angle of the generator according to the first embodiment is π / 2; Fig. 8 is a view showing a state in which the phase angle of the generator according to the first embodiment is π; Fig. 9 is a view showing a state in which the phase angle of the generator according to the first embodiment is 3π / 2; Fig. 10 is a cross-sectional view of the generator according to the second embodiment; Fig. 11 is a cross-sectional view showing an armature coil of the bicycle generator according to the second embodiment; Fig. 12 is a view showing a state in which the phase angle of the generator according to the second embodiment is zero; Fig. 13 is a view showing a state in which the phase angle of the generator according to the second embodiment is π / 2; Fig. 14 is a view showing a state in which the phase angle of the generator according to the second embodiment is π; and Fig. 15 is a view showing a state where the phase angle of the generator according to the second embodiment is 3π / 2.

[0012] In the description of each of the following embodiments, the same structural elements are given the same reference numerals, and overlapping descriptions are omitted. Furthermore, for the convenience of description, some structural elements have been omitted from each drawing where appropriate.

[0013] Fig. 1 is a partial side view showing a bicycle 12 equipped with the bicycle generator 10 (hereinafter simply referred to as the generator 10) according to the first embodiment. The bicycle 12 includes a front fork 18 rotatably supported on the steering head 16 of the main frame 14, and a hub shaft 20 fixed to the front fork 18. The front wheel 22 as a wheel is rotatably supported on the hub shaft 20. A headlight 24 is mounted on the side of the front wheel 22, and the power obtained from the generator 10 is supplied to the headlight 24.

[0014] The front wheel 22 further includes a tubular hub 26 rotatably mounted on the hub shaft 20 via an axle bearing (not shown), a plurality of spokes 28 secured to the outer peripheral portion of the hub 26, and a rim 30 secured to the outer peripheral portion of each spoke 28. A tire 32 is secured to the rim 30.

[0015] Fig. Figure 2 is a front view showing the configuration of the hub 26 of the bicycle 12 and its surroundings. Other configurations of the hub 26 are indicated by the two-dot chain line. A generator 10, which acts as a hub dynamo, is housed in the hub 26. A bolt 34 is formed at both ends of the hub shaft 20 in the axial direction. The hub shaft 20 is fixed to the front fork 18 together with the hub 26 by tightening a nut 36 screwed onto the respective bolts 34.

[0016] Fig. 3 is a cross-sectional view of the generator 10. This drawing is a cross-sectional view taken perpendicular to the axial direction of the rotation center of a rotor 40 described below and a section taken on the line AA of Fig. 2. The hub 26 has been omitted from the present drawing. Moreover, in the following description, the terms "axial direction," "circumferential direction," and "radial direction" are used to describe the positional relationships of the constituent elements of the stator 38 and the rotor 40, as described below. Of the above, "axial direction" refers to the axial direction of the rotation center of the rotor 40, and "circumferential direction" and "radial direction" refer to the circumferential direction and the radial direction relative to the rotation center of the rotor 40, respectively.

[0017] The generator 10 has a stator 38 fixed to the hub shaft 20 and a rotor 40 rotatably mounted on the hub shaft 20. The generator 10 is an external rotor generator, with the rotor 40 arranged on the outer peripheral side of the stator 38. Furthermore, the generator 10 is a synchronous generator. The rotor 40 is rotatably integral with the hub 26, which is part of the front wheel 22. When the front wheel 22 rotates, the rotor 40 rotates with it.

[0018] Overall, the rotor 40 is annular. The rotor 40 includes a rotor core 46 having an annular base body 42 and a plurality of salient pole rotor sections 44 provided on the inner peripheral side of the annular base body 42, which is the side opposite the stator 38 of the annular base body 42.

[0019] Each salient pole rotor section 44 protrudes from the annular base body 42 toward the radially inner side, which is the side opposite the stator 38. Each salient pole rotor section 44 is formed to have a width corresponding to the predetermined width w. Here, "corresponding" includes exactly the same case and substantially the same case. The interpretation of "corresponding" will be the same hereinafter.

[0020] The salient pole rotor sections 44 are arranged at intervals at positions each circumferentially shifted by an angle corresponding to a predetermined angle λ (hereinafter also referred to as the salient pole pitch). In the present embodiment, a total of 20 salient pole rotor sections 44 are provided, and the salient pole pitch λ is set to 18° (= 360° / 20). This salient pole pitch λ corresponds to the phase angle 2π of the generator 10; when the rotor 40 is rotated by the salient pole pitch λ, an alternating current power constituting one cycle is generated from the armature coil 60, as described below.

[0021] Overall, the stator 38 is annular. The stator 38 includes a plurality of magnets 48 arranged at intervals in the circumferential direction, and a plurality of stator cores 50A and 50B, one of which is arranged for each interval between the plurality of magnets 48. The plurality of magnets 48 and the plurality of stator cores 50A and 50B are alternately arranged in the circumferential direction and form a ring shape by bonding with an adhesive or the like. In the present embodiment, a total of four each of the magnets 48 and the stator cores 50A and 50B, that is, an even number, are provided.

[0022] The magnet 48 is a permanent magnet. The magnet 48 is inserted into the magnetic field of the armature coil 60 described below. The circumferential direction of the magnet 48 is the magnetization direction. The magnets 48 are arranged at intervals at positions circumferentially offset by corresponding angles. The magnetic poles opposite in the circumferential direction of the plurality of magnets 48 that are adjacent to each other in the circumferential direction have the same polarity. The magnets 48 are plate-shaped and extend along the radial direction, so that they radially divide the stator cores 50A and 50B that are adjacent to each other in the circumferential direction.

[0023] The stator cores 50A and 50B and the rotor core 46 described above are formed by layering a plurality of metal plates in the axial direction of the rotor 40. The material of the metal plates will be a soft magnetic body such as an electromagnetic steel sheet.

[0024] The stator cores 50A and 50B include a first stator core 50A located adjacent to one of the other magnets 48 arranged circumferentially (for example, the magnet 48 on the top side in the drawing) in one of the circumferential directions (clockwise in the drawing), and a second stator core 50B located adjacent to one of the magnets 48 in the other circumferential direction (counterclockwise in the drawing). In the present embodiment, two first stator cores 50A and two second stator cores 50B are provided.

[0025] Each of the stator cores 50A and 50B includes the coil slot portions 52 located on the circumferentially opposite sides of the other magnets 48 arranged in the circumferential direction. One coil slot portion 52 is provided for each pitch between the plurality of magnets 48. One coil slot portion 52 is formed for each of the first stator cores 50A and each of the second stator cores 50B. The coil slot portion 52 is formed to be recessed radially inward from the radially outer side, starting from the side opposite the rotor 40.

[0026] In addition to the coil slot portion 52, each of the stator cores 50A and 50B includes an arcuate flux path connecting portion 54 located adjacent to the coil slot portion 52 on the bottom side, and flux path portions 56A and 56B located adjacent to the coil slot portion 52 on circumferentially opposite sides. The flux path connecting portion 54 connects the flux path portions 56A and 56B in the circumferential direction. The flux path portions 56A and 56B extend toward the radially outer side, which is the side opposite the rotor 40. The force path portions 56A and 56B include a first force path portion 56A located adjacent to the coil groove portion 52 in one circumferential direction (clockwise in the drawing) and a second force path portion 56B located adjacent to the other circumferential direction (counterclockwise in the drawing).

[0027] Fig. 4 is a cross-sectional view showing an armature coil 60 of the generator 10. The drawing also shows the winding direction B of the armature coil 60 in one of the axial directions of the rotor 40 (the near side of the lamination). The stator 38 further includes the armature coils 60 wound between the coil slot portions 52 located adjacent to each of the magnets 48 on circumferentially opposite sides, so as to straddle the magnets 48 in the circumferential direction. The armature coils 60 are provided corresponding to each of the plurality of magnets 48, and the number of them is the same as the number of magnets 48. The armature coils 60 are wound so as to surround the corresponding magnets 48 from the circumferentially opposite sides and both axial sides.

[0028] The armature coil 60 is wound by means of a concentrated winding between the coil slot sections 52, which are adjacent to one another in the circumferential direction, but can also be wound by means of a distributed winding so that it passes through the other coil slot sections 52. The armature coils 60, which are adjacent to one another in the circumferential direction, are wound in the opposite winding direction B, but can also be wound in the same direction.

[0029] As described below, when the rotor 40 rotates, the AC power with the same phase is generated in the armature coil 60. The armature coils 60 are electrically connected in parallel, and the output terminals are connected to a rectifier circuit (not shown), and a single-phase AC power is output to the rectifier circuit. The rectifier circuit converts the AC power into DC power by rectifying, smoothing, etc., and supplies the DC power to the headlight 24 (referring to Fig. 1) as the external electrical device. However, the armature coils 60 can also be electrically connected in series.

[0030] Here, as in Fig. 3, the stator 38 includes a first salient pole stator portion 62A provided at each of a plurality of first magnetic path portions 56A opposite the rotor 40, and a second salient pole stator portion 62B provided at each of a plurality of second magnetic path portions 56B opposite the rotor 40. Each of the salient pole stator portions 62A and 62B projects from each of the magnetic path portions 56A and 56B toward the radially outer side, which is the side opposite the rotor 40. Two first salient pole stator portions 62A are provided per one first magnetic path portion 56A, and two second salient pole stator portions 62B are provided per one second magnetic path portion 56B. In the present embodiment, a total of 16 salient pole stator portions 62A and 62B are provided.

[0031] The salient pole stator portions 62A and 62B are arranged with a predetermined gap therebetween in the radial direction relative to the salient pole rotor portion 44. The salient pole stator portions 62A and 62B are formed to have the same width as the width w of the salient pole rotor portion 44.

[0032] Fig. 5 is a view showing the positional relationship of the salient pole rotor section 44 and the salient pole stator sections 62A and 62B. In the present drawing, to distinguish a part of the plurality of salient pole sections, an alphabetic letter such as (a) is indicated at the end of each code. There are cases where the same applies in the following drawings.

[0033] The plurality of first salient pole post portions 62A provided on a first magnetic path portion 56A are arranged at positions each circumferentially shifted by an angle corresponding to the salient pole pitch λ of each salient pole rotor portion 44. The plurality of second salient pole post portions 62B provided on a second magnetic path portion 56B are arranged at positions each circumferentially shifted by an angle corresponding to the salient pole pitch λ. Further, the other second salient pole post portions 62B circumferentially adjacent to the first salient pole post portion 62A are arranged at positions each circumferentially shifted by an angle corresponding to the salient pole pitch λ × 1.5.

[0034] Therefore, when n is a natural number greater than or equal to 1, the first salient pole post portions 62A are arranged at positions each circumferentially shifted by an angle corresponding to λ × n with respect to the other first salient pole post portions 62A. For example, the first salient pole post portion 62A(d) is shifted by λ × 4 (= λ × 1.5 + λ × 1.5) with respect to another first salient pole post portion 62A(g) located clockwise therebelow, and shifted by λ × 1.0 with respect to another first salient pole post portion 62A(c) located counterclockwise therebelow. Similarly, the second salient pole post portions 62B are arranged at the positions each shifted circumferentially by an angle corresponding to λ × n with respect to the other second salient pole post portions 62B.

[0035] Furthermore, the second salient pole post portions 62B are arranged at positions each circumferentially shifted by an angle corresponding to λ × (n + 0.5) relative to the first salient pole post portions 62A. For example, the second salient pole post portion 62B(e) is shifted by λ × 2.5 (= λ + λ × 1.5) relative to the first salient pole post portion 62A(g) located clockwise therefrom, and is shifted by λ × 1.5 relative to the first salient pole post portion 62A(d) located counterclockwise therefrom.

[0036] The operation of the above generator 10 is described using the Fig. 6 to 9. Each drawing shows a state in which the rotor 40 is rotated in direction P by a phase angle π / 2. Furthermore, Fig. 6 and Fig. 8, of the magnetic flux flowing in the rotor core 46, etc., mainly the main magnetic flux is shown, and the leakage magnetic flux is omitted. Fig. 7 and Fig. 9 the flow of the magnetic leakage flux. Below is the phase angle in the position relationship of Fig. 6 zero, and the phase angles in Fig. 7 to Fig. 9 are π / 2, π, and 3π / 2. Furthermore, for convenience, an "O" mark is indicated for a salient pole rotor section 44(a).

[0037] As in Fig. 6, when the phase angle is zero, the first salient pole stator portions 62A are located at positions overlapping the salient pole rotor portions 44 in the vicinity thereof across the entire width in the circumferential direction, as viewed from the radial direction of the rotor 40. Further, the second salient pole stator portions 62B are located at positions not overlapping the salient pole rotor portions 44 in the vicinity thereof across the entire width in the circumferential direction, that is, at positions shifted in the circumferential direction, as viewed from the radial direction of the rotor 40.In other words, the area where the first salient pole stator portion 62A overlaps a nearby salient pole rotor portion 44 in the circumferential direction (hereinafter referred to as the first overlap area) is larger than the area where the second salient pole stator portion 62B overlaps another nearby salient pole rotor portion 44 in the circumferential direction (hereinafter referred to as the second overlap area). Therefore, a second magnetic resistance R2, which is the magnetic resistance between the second salient pole stator portion 62B and the salient pole rotor portion 44, becomes significantly larger than a first magnetic resistance R1, which is the magnetic resistance between the first salient pole stator portion 62A and the salient pole rotor portion 44.

[0038] As a result, due to the magnetic flux generated from a magnet 48, a closed line of force path Mp is formed, which passes through the first salient pole stator portion 62A of the first stator core 50A, which is located adjacent to one magnetic pole face of the magnet 48, and the first salient pole stator portion 62A of the second stator core 50B, which is located adjacent to the other magnetic pole face.For example, the magnet 48(b) in the upper part of the drawing forms a line of force path Mp which crosses the line of force connecting portion 54 of the first stator core 50A(b) → the first line of force path portion 56A of the first stator core 50A(b) → the first salient pole stator portion 62A(g) → the salient pole rotor portion 44(g) → the annular base body 42 → the rotor 40 → the salient pole rotor portions 44(c) and (d) → the first salient pole stator portions 62A(c) and 62A(d) → the first line of force path portion 56A of the second stator core 50B(a) and returns to the original magnet 48(b).

[0039] This magnetic flux path Mp is formed to interlink in the radial direction in each of the armature coils 60. At this time, since the magnetic poles of the plurality of magnets 48 facing each other in the circumferential direction have the same polarity, the rotation direction of the magnetic flux path Mp generated by magnets 48 adjacent to each other in the circumferential direction will be opposite. For example, a magnetic flux path Mp generated by the magnet 48(b) in the upper part of the drawing will be counterclockwise, and a magnetic flux path Mp generated by the magnet 48(b) on the left side of the drawing will be clockwise. As a result, the magnetic flux generated by the separate magnets 48 will interlink in the same orientation in one armature coil 60.For example, the magnetic flux generated by magnet 48(b) in the upper part of the drawing and the magnetic flux generated by magnet 48(a) on the left side of the drawing will concatenate in the same orientation in armature coil 60(b) in the upper part of the drawing.

[0040] As in Fig. As shown in Figure 7, at a phase angle π / 2, the first salient pole stator sections 62A, viewed from the radial direction of the rotor 40, are located at the positions that overlap the salient pole rotor sections 44 in their vicinity substantially over half the width in the circumferential direction. The same applies to the second salient pole stator sections 62B. In other words, the first overlap area of ​​the first salient pole stator section 62A with respect to the salient pole rotor section 44 will correspond to the second overlap area of ​​the second salient pole stator section 62B with respect to the salient pole rotor section 44. Therefore, the first magnetic resistance R1 and the second magnetic resistance R2 will become equal.

[0041] As a result, due to the magnetic flux generated by a magnet 48, a closed line of force path Mp is formed, which passes through the second salient pole stator portion 62B of the first stator core 50A, which is located adjacent to one magnetic pole face of the magnet 48, and the first salient pole stator portion 62A of the second stator core 50B, which is located adjacent to the other magnetic pole face.For example, the magnet 48(b) in the upper part of the drawing forms a magnetic path Mp that traverses the second magnetic path portion 56B of the first stator core 50A(b) → the second salient pole stator portions 62B(e) and (f) → the salient pole rotor portions 44(e) and 44(f) → the annular base 42 → the rotor 40 → the salient pole rotor portions 44(c) and 44(d) → the first salient pole stator portions 62A(c) and (d) → the first magnetic path portion 56A of the second stator core 50B(a) and returns to the original magnet 48(b). This magnetic path Mp reciprocates in the radial direction in each armature coil 60 and is configured to interlink in each armature coil 60.

[0042] As in Fig. 8, at a phase angle π, the first salient pole stator portions 62A, viewed from the radial direction of the rotor 40, are located at the positions that do not overlap the salient pole rotor portions 44 in their vicinity across the entire width in the circumferential direction, that is, the positions that are shifted in the circumferential direction. Further, the second salient pole stator portions 62B, viewed from the radial direction of the rotor 40, are located at positions that overlap the salient pole rotor portions 44 in their vicinity across the entire width in the circumferential direction. In other words, the second overlap area of ​​the second salient pole stator portion 62B with respect to the salient pole rotor portion 44 will be larger than the first overlap area of ​​the first salient pole stator portion 62A with respect to the salient pole rotor portion 44. Therefore, the second magnetic resistance R2 will become significantly larger than the first magnetic resistance R1.

[0043] As a result, due to the magnetic flux generated by a magnet 48, a closed line of force path Mp is formed, which passes through the second salient pole stator portion 62B of the first stator core 50A, which is located adjacent to one magnetic pole face of the magnet 48, and the second salient pole stator portion 62B of the second stator core 50B, which is located adjacent to the other magnetic pole face.For example, the magnet 48(b) in the upper part of the drawing forms a magnetic path Mp that crosses the second magnetic path portion 56B of the first stator core 50A(b) → the second salient pole stator portions 62B(e) and (f) → the salient pole rotor portions 44(e) and 44(f) → the annular base body 42 → the rotor 40 → the salient pole rotor portions 44(a) and 44(t) → the second salient pole stator portions 62B(a) and 62B(b) → the magnetic path connecting portion 54 of the second stator core 50B(a) and returns to the original magnet 48(b).

[0044] This force line path Mp is designed to interlink in each of the armature coils 60 in the radial direction. At this time, the force line path Mp is designed such that the interlinking orientation in the armature coil 60 will be the opposite direction in the radial direction compared to a phase angle of zero (relative to Fig. 6).

[0045] As in Fig. As shown in Figure 9, at a phase angle of 3π / 2, the first salient pole stator portions 62A, viewed from the radial direction of the rotor 40, are located at positions overlapping the salient pole rotor portions 44 in their vicinity by substantially half the circumferential width. Furthermore, the second salient pole stator portions 62B, viewed from the radial direction of the rotor 40, are located at positions overlapping the salient pole rotor portions 44 in their vicinity by half the circumferential width. Therefore, the first magnetic resistance R1 and the second magnetic resistance R2 become equal. As a result, the same magnetic path Mp as that at a phase angle of π / 2 is formed.

[0046] As described above, in a state where the phase angle is zero (hereinafter also referred to as the first state), the second magnetic resistance R2 becomes significantly larger than the first magnetic resistance R1, and in a state where the phase angle is 3π / 2 (hereinafter referred to as the second state), the first magnetic resistance R1 becomes significantly larger than the second magnetic resistance R2. When the rotor 40 rotates, the first state and the second state are alternately switched.

[0047] As in Fig. 6 and Fig. As shown in Figure 8, in an armature coil 60 (for example, armature coil 60(b)), a line of force path Mp interlacing in one radial direction is formed in the first state, and a line of force path Mp interlacing in the other radial direction is formed in the second state. That is, when switching between the first state and the second state, switching is performed such that the orientation of the magnetic flux interlacing in the radial direction in each armature coil 60 is reversed, thereby generating an AC-induced electromotive force in each armature coil 60. At this time, the AC power of the same phase is generated in each armature coil 60. In this way, in the generator 10, the locations of the plurality of salient-pole rotor portions 44 and the plurality of salient-pole stator portions 62A and 62B are determined so that the first state and the second state are alternately switched.

[0048] The operation and effects of the generator 10 will now be described.

[0049] In general, the frequency f (Hz) of a generator satisfies the relationship of the following formula (1) between the rotational speed N (rpm) of the rotor and the number of poles P of the generator. N=120×f / P

[0050] The present inventors have discovered that in the generator 10 according to the present embodiment, the number obtained by multiplying the number of salient pole rotor sections 44 by two is the number of poles P of the generator. This finding was confirmed by the analysis using the Fig. 3. In this analysis, the rotational speed N of the rotor 40 was set to 120 (rpm), thereby obtaining the frequency f (Hz) of the power generated by the armature coil 60. As a result, a frequency f of 40 (Hz) was obtained, and by formula (1), the number obtained by multiplying the number of salient-pole rotor sections 44 (20) by two was confirmed as the number of poles P of the generator.

[0051] Thus, in the generator 10 according to the present embodiment, as long as the salient pole rotor sections 44 and the salient pole stator sections 62A and 62B are located at the predetermined positions, the frequency of the induced electromotive force increases as the number of salient pole rotor sections 44 increases, and high-frequency AC power is easily obtained even when the rotational speed of the rotor 40 is low. However, since the voltage of the induced electromotive force is proportional to the product of the frequency and the magnetic flux interlinked in the armature coil 60, the ability to obtain high-frequency AC power means that corresponding high-voltage AC power can be obtained.

[0052] Furthermore, the first salient pole stator portion 62A and the second salient pole stator portion 62B are provided at locations between the magnet 48 and the coil groove portion 52, so the distances therebetween can be separated even more easily. Therefore, even if they are excited to different polarities by the magnet 48, the generation of leakage magnetic flux between the first salient pole stator portion 62A and the second salient pole stator portion 62B can be more easily suppressed. For this reason, suppression of leakage magnetic flux therebetween becomes easy while reducing the outer diameter of the rotor 40 and the stator 38 of the generator 10.However, the ability to suppress the generation of leakage magnetic flux between the first salient pole stator portion 62A and the second salient pole stator portion 62B means that a reduction in the magnetic flux interlinking in the armature coil 60 can be suppressed and it becomes easier to obtain a sufficient voltage output from the generator 10.

[0053] Furthermore, for example, in a three-phase AC generator in which an armature coil is wound around each of a plurality of salient pole sections of a stator, such as the one disclosed in Japanese Patent Application Laid-Open No. 2012-182961, the number of armature coils increases along with an increase in the number of magnetic poles of the rotor, resulting in a correspondingly high cost and a deterioration in assembly properties. In this regard, in the present embodiment, to obtain high-frequency AC performance, only the number of salient pole rotor sections 44 needs to be increased, and the number of magnets 48 or armature coils 60 does not need to be increased; therefore, the number of parts can be reduced, which in turn reduces costs, and good assembly properties can be achieved.

[0054] Furthermore, in a conventional claw-pole generator, the magnetic flux flowing from the rotor magnet into the claw portions of each stator core changes direction to the axial direction in the claw portion and flows toward the base body of the claw portion. The cross-sectional area of ​​the magnetic path perpendicular to the magnetic path direction of this claw portion (axial direction) is determined according to the thickness and circumference of the claw portion in the radial direction. Here, if the outer diameter is reduced without changing the axial length of the generator, the claw portion of the stator core becomes thinner in the circumferential direction without changing the axial length, so that the gap area facing the magnet becomes thin and the thickness in the radial direction is reduced; as a result, the cross-sectional area of ​​the magnetic path at the base body of the claw portion becomes small.Therefore, the magnetic flux absorbed by the claw portion of the stator core at the gap surface tends to be concentrated at the base portion of the claw portion, where the cross-sectional area of ​​the magnetic path is small, and magnetic saturation is likely to occur at the base portion. As a result, the magnetic flux interlinked in the armature coil becomes difficult to flow, and obtaining sufficient voltage output from the generator also becomes difficult.

[0055] In this regard, in the generator 10 according to the present embodiment, the magnetic flux in the salient pole stator portions 62A and 62B of the stator core 50 flows not in the axial direction but in the radial direction. The cross-sectional area of ​​the magnetic path perpendicular to the magnetic path direction of these salient pole stator portions 62A and 62B (radial direction) is determined according to the axial length and circumference of the salient pole stator portions 62A and 62B, which are not easily changed even if the outer diameter of the generator 10 is reduced. For this reason, even if the outer diameter of the generator 10 is reduced, the cross-sectional area of ​​the magnetic path of the salient pole stator portions 62A and 62B can be secured by increasing the axial length of the stator core 50.Therefore, even if the outer diameter of the generator 10 is reduced, the occurrence of magnetic saturation of the salient pole stator portions 62A and 62B can be suppressed, a reduction in the magnetic flux interlinking in the armature coil 60 can be suppressed, and obtaining a sufficient voltage output from the generator 10 becomes easier.

[0056] Furthermore, each time the first state and the second state are switched, the orientation of the line of force path Mp generated by the one magnet 48 in the armature coil 60 can be reversed, allowing a greater amount of change in the magnetic flux interlinked in the armature coil 60 compared to a non-reversed orientation; therefore, high-voltage AC power can be obtained even more easily. Furthermore, each time the first state and the second state are switched, the orientation of the line of force path Mp generated in the one armature coil 60 using one magnet 48 can be reversed; therefore, high-voltage AC power can be obtained more easily while simultaneously reducing the number of magnets 48.

[0057] Furthermore, each of the first salient pole stator sections 62A is shifted relative to another of the first salient pole stator sections 62A by an angle corresponding to λ × n, and each of the second salient pole stator sections 62B is shifted relative to the first salient pole stator section 62A by an angle corresponding to λ × (n + 0.5). Therefore, the relative positions of the salient pole stator sections 62A and 62B with respect to the salient pole rotor section 44 can be aligned, the manner of changing the magnetic flux path Mp formed by the magnetic flux generated from the magnets 48 can be adjusted, and an AC power with the same phase can be more easily obtained with the armature coil 60.

[0058] Furthermore, since each of the stator cores 50A and 50B and the rotor core 46 can be formed by laminating a plurality of metal plates, the excitation loss due to an eddy current in the portion through which the main magnetic flux passes can be significantly suppressed.

[0059] Fig. Fig. 10 is a cross-sectional view showing the generator 10 according to the second embodiment, and Fig. 11 is a cross-sectional view showing an armature coil 60 of the generator 10. In the example of Fig. 3, a total of 20 salient pole rotor sections 44 of the rotor 40 are provided, but in the present embodiment, a total of 18 are provided. The salient pole pitch λ will be 20° (= 360° / 18).

[0060] In the example of Fig. 3, a total of four magnets 48 and stator cores 50A and 50B of the stator 38 are provided, but in the present embodiment, a total of two are provided. Furthermore, in the example of Fig. 3, two first stator cores 50A and two second stator cores 50B are provided, but in the present embodiment, only one is provided. Furthermore, in the example of Fig. 3, two first salient pole stator sections 62A and two second salient pole stator sections 62B are provided on the first magnetic path section 56A and the second magnetic path section 56B, respectively. However, in the present embodiment, four are provided. Thus, the number of the salient pole rotor sections 44 and the salient pole stator sections 62A and 62B is not particularly limited.

[0061] The operation of the above generator 10 is described using the Fig. 12 to Fig. 15. Each drawing shows a state in which the rotor 40 is rotated in the direction P by a phase angle π / 2. Furthermore, Fig. 12 and Fig. 14 of the magnetic flux flowing in the rotor core 46, etc., mainly the main magnetic flux is shown, and the leakage magnetic flux is omitted. Fig. 13 and Fig. 15 the flow of the magnetic leakage flux. Below is the phase angle in the position relationship of Fig. 12 zero, and the phase angles in Fig. 13 to Fig. 15 are π / 2, π and 3π / 2.

[0062] As in Fig. As shown in Figure 12, when the phase angle is zero, the first salient pole stator portions 62A, viewed from the radial direction of the rotor 40, are located at positions that overlap the salient pole rotor portions 44 in their vicinity across the entire width in the circumferential direction. The second salient pole stator portions 62B are located at positions that do not overlap the salient pole rotor portions 44 in their vicinity across the entire width in the circumferential direction, that is, at positions that are circumferentially shifted when viewed from the radial direction of the rotor 40. In other words, the first overlap area of ​​the first salient pole stator portion 62A with respect to the salient pole rotor portion 44 will be larger than the second overlap area of ​​the second salient pole stator portion 62B with respect to the salient pole rotor portion 44.Thus, a closed line of force path Mp is formed so as to interlink in the radial direction in each armature coil 60, just as in the first embodiment.

[0063] As in Fig. As shown in Figure 13, when the phase angle is π / 2, the first salient pole stator portions 62A, viewed from the radial direction of the rotor 40, are located at positions overlapping the salient pole rotor portions 44 in their vicinity by half the circumferential width. Further, the second salient pole stator portions 62B, viewed from the radial direction of the rotor 40, are located at positions not overlapping the salient pole rotor portions 44 in their vicinity by half the circumferential width. In other words, the first overlapping area of ​​the first salient pole stator portion 62A with respect to the salient pole rotor portion 44 will correspond to the second overlapping area of ​​the second salient pole stator portion 62B with respect to the salient pole rotor portion 44. Thus, a closed line of force path Mp is formed so as to reciprocate in the radial direction in each of the armature coils 60, just as in the first embodiment.

[0064] As in Fig. As shown in Figure 14, when the phase angle is π, the first salient pole stator portions 62A, viewed from the radial direction of the rotor 40, are located at positions that do not overlap the salient pole stator portions 44 in their vicinity across the entire width in the circumferential direction, that is, at positions that are shifted in the circumferential direction. The second salient pole stator portions 62B, viewed from the radial direction of the rotor 40, are located at positions that overlap the salient pole stator portions 44 in their vicinity across the entire width in the circumferential direction. In other words, the second overlap area of ​​the second salient pole stator portion 62B with respect to the salient pole stator portion 44 will be larger than the first overlap area of ​​the first salient pole stator portion 62A with respect to the salient pole stator portion 44.Thus, a closed line of force path Mp is formed so as to interlink in the radial direction in each armature coil 60, just as in the first embodiment.

[0065] As in Fig. As shown in Figure 15, when the phase angle is 3π / 2, the first salient pole stator portions 62A, viewed from the radial direction of the rotor 40, are located at positions overlapping the salient pole rotor portions 44 in their vicinity by half the circumferential width. Furthermore, the second salient pole stator portions 62B, viewed from the radial direction of the rotor 40, are located at positions overlapping the salient pole rotor portions 44 in their vicinity by half the circumferential width. As a result, the same magnetic path Mp is formed as when the phase angle is π / 2.

[0066] The inventors concerned have discovered that, in the above generator 10, the number obtained by multiplying the number of salient pole rotor sections 44 by two is the number of poles P of the generator. This finding was confirmed by the analysis using the formula given in Fig. 10. In this analysis, the rotational speed N of the rotor 40 was set to 120 (rpm), thereby obtaining the frequency f (Hz) of the power generated by the armature coil 60. As a result, a frequency f of 36 (Hz) was obtained, and by formula (1), the number obtained by multiplying the number of salient-pole rotor sections 44 (18) by two was confirmed as the number of poles P of the generator.

[0067] Therefore, in the generator 10 according to the present embodiment, the frequency of the induced electromotive force increases with an increase in the number of salient-pole rotor sections 44, and high-frequency AC power can be more easily obtained even when the rotational speed of the rotor 40 is low, just like in the first embodiment. In other respects, the same operation and effects as in the first embodiment can be obtained.

[0068] The present invention has been described above based on the embodiments, but the embodiments merely illustrate the principles and applications of the present invention. Furthermore, various modifications and changes of arrangement can be made to the embodiment without departing from the spirit of the present invention as defined in the claims.

[0069] The generator 10 was described using the example of a bicycle generator, but its use is not limited thereto. Furthermore, if the generator 10 is to be a bicycle generator, the rotor 40 only needs to rotate in conjunction with the rotation of a rotating part of the bicycle 12. The rotating part was described here using the example of the front wheel 22; in addition to a hub shaft and a crank, the part can also be a pulley or the like of a rear derailleur (chain tensioner). Furthermore, the generator 10 can be designed not only as a hub dynamo, but also as a roller dynamo or the like. An external rotor generator was shown as an example of the generator 10, but the generator can also be an internal rotor generator, in which the rotor 40 is arranged on the inner circumferential side of the stator 38.

[0070] An example was described in which the first stator core 50A and the second stator core 50B of the stator 38 are formed as separate bodies, but the two may be integrally formed. Furthermore, an example was described in which the width of the salient pole stator portions 62A and 62B is equal to the width w of the salient pole rotor portion 44, but the width may be less than or equal to the width w of the salient pole rotor portion 44, or greater than or equal to the width w of the salient pole rotor portion 44.

[0071] The positions of the salient pole rotor portion 44 and the salient pole stator portions 62A and 62B are not limited to the examples in the drawings, as long as a first state in which the second magnetic resistance is larger than the first magnetic resistance and a second state in which the first magnetic resistance is larger than the second magnetic resistance are to be alternately switched.

[0072] When these conditions are met, the first state may be configured such that the first overlap area of ​​the first salient pole stator portion 62A with respect to the salient pole rotor portion 44 is larger than the second overlap area of ​​the second salient pole stator portion 62B with respect to the salient pole rotor portion 44. Furthermore, when this condition is met, the second state may be configured such that the second overlap area is larger than the first overlap area.

[0073] For example, in Fig. 6 and Fig. 12 describes an example in which, in the first state, the first overlapping region is an area over the entire circumferential width of the first salient pole post portion 62A, and there is no second overlapping region. In addition to the above, in the first state, the first overlapping region may be the same area as in the example of the drawing, while the second overlapping region is set as the area overlapping less than or exactly half the width of the second salient pole post portion 62B with respect to the salient pole rotor portion 44 located near the second salient pole post portion 62B. Here, the second salient pole post portion 62B will be located at a position shifted circumferentially with respect to one of the salient pole rotor portions 44, so the second overlapping region will be smaller than the first overlapping region.

[0074] Similar to this, Fig. 8 and Fig. 14 describes an example in which, in the second state, the second overlapping region is a region across the entire circumferential width of the second salient pole portion 62B, and there is no first overlapping region. In addition to the above, in the second state, for example, the second overlapping region may be the same region as in the example of the drawing, while the first overlapping region is set to be an area overlapping less than or equal to half the width of the first salient pole portion 62A with respect to the salient pole rotor portion 44 located near the first salient pole portion 62A. REFERENCE SYMBOL 10 Generator 12 bicycles 22 Front wheel (rotating section) 26 Hub 38 stands 40 runners 44 Salient pole rotor section 46 rotor core 48 Magnet 50A first stator core 50B second stator core 52 Coil groove section 56A first power line path section 56B second force line path section 60 armature coil 62A first salient pole stator section 62B second salient pole stator section

Claims

[1] Generator (10) which: a runner (40) and a stand (38) which: a plurality of magnets (48) arranged at intervals in the circumferential direction such that magnetic poles opposite each other in the circumferential direction have the same polarity; a stator core (50A, 50B) having coil slot portions (52) arranged on circumferentially opposite sides of the magnets (48); and an armature coil (60) wound between the coil slot portions (52) so that the magnets (48) are spread apart in the circumferential direction, wherein the rotor (40) comprises a rotor core (46) having a plurality of salient pole rotor portions (44) formed at intervals in the circumferential direction, and the stator core (50A, 50B) has a first salient pole stator section (62A) provided at a first force path section (56A) located adjacent to the coil slot sections (52) in one of the circumferential directions, and a second salient pole stator section (62B) provided at a second force path section (56B) located adjacent to the coil slot sections (52) in the other circumferential direction, the first and second salient pole stator sections (62A, 62B) being opposite the rotor (40), wherein the first salient pole section (62A) protrudes from the first force path section (56A) and the second salient pole section (62B) protrudes from the second force path section (56B) toward the radially outer side, which is the side opposite the rotor (40), and wherein at least two first salient pole sections (62A) are provided per one first force path section (56A) and at least two second salient pole sections (62B) are provided per one second force path section (56B). [2] The generator (10) according to claim 1, wherein the plurality of salient pole rotor sections (44), the first salient pole stator section (62A), and the second salient pole stator section (62B) are arranged such that, when the rotor (40) rotates, a first state in which a second magnetic resistance is greater than a first magnetic resistance and a second state in which the first magnetic resistance is greater than the second magnetic resistance are alternately switched, wherein the first magnetic resistance is defined as a magnetic resistance between the first salient pole stator section (62A) and the salient pole rotor section (44), and the second magnetic resistance is defined as a magnetic resistance between the second salient pole stator section (62B) and the salient pole rotor section (44). [3] Generator (10) according to claim 1 or 2, wherein the plurality of salient pole rotor sections (44), the first salient pole stator section (62A) and the second salient pole stator section (62B) are arranged so that a first state and a second state are alternately switched, the first state is defined as a state in which an interference area between the first salient pole stator portion (62A) and the salient pole rotor portion (44) located near the first salient pole stator portion (62A) in the circumferential direction, viewed from a radial direction relative to a rotation center of the rotor (40), is larger than an interference area between the second salient pole stator portion (62B) and the salient pole rotor portion (44) located near the second salient pole stator portion (62B) in the circumferential direction, viewed from the radial direction, and the second state is defined as a state in which an interference area between the second salient pole stator portion (62B) and the salient pole rotor portion (44) located near the second salient pole stator portion (62B) in the circumferential direction, as viewed from the radial direction, is larger than the interference area between the first salient pole stator portion (62A) and the salient pole rotor portion (44) located near the first salient pole stator portion (62A) in the circumferential direction, as viewed from the radial direction. [4] Generator (10) according to one of the preceding claims, wherein the plurality of salient pole rotor sections (44) are arranged at locations which are each shifted in the circumferential direction by an angle corresponding to a predetermined angle λ, the first salient pole stator sections (62A) are arranged at positions each shifted in the circumferential direction by an angle corresponding to λ × n (n is an integer of 1 or greater) relative to the other first salient pole stator sections (62A), and the second salient pole post sections (62B) are arranged at positions which are each shifted in the circumferential direction by an angle corresponding to λ × (n + 0.5) with respect to the first salient pole post sections (62A). [5] Generator (10) according to one of the preceding claims, wherein the rotor core (46) and the stator core (50A, 50B) are formed by laminating a plurality of metal plates in the axial direction of a rotation center of the rotor (40). [6] Generator (10) according to one of the preceding claims, wherein the generator (10) is a bicycle generator (10) in which the rotor (40) is rotatable in conjunction with the rotation of a rotating part of the bicycle (12). [7] Generator (10) according to one of the preceding claims, wherein the generator (10) is a bicycle hub dynamo.

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