JP2008301587A - Power generator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power generator wherein two or more permanent magnets 4, 5 strong in magnetic force can be effectively used to obtain large induced electromotive force by alternately switching magnetic paths through which magnetic fluxes Φ from the permanent magnets 4, 5 pass. <P>SOLUTION: The power generator includes: a rotor 1 with pole teeth 1a formed thereon; a stator 2 with pole teeth 2a, 2b respectively formed in two sets of pole tooth portions in which stator the pole teeth 2a, 2b of each set of pole tooth portions are brought close to the pole teeth 1a of the rotor 1 and relatively rotated and thus the narrow and wide gaps between the pole teeth 2a, 2b of the two sets of pole tooth portions are alternated with a change in electrical angle; a coil 3 wound between the two sets of pole tooth portions of the stator 2; two permanent magnets 4, 5 whose north magnetic pole faces are fixed in contact with the vicinity of each set of pole tooth portions of the stator 2; and two auxiliary cores 6, 7 that are fixed in contact with the south magnetic pole face of each permanent magnet 4, 5 and constantly brought close to the rotor 1 with a narrow gap in-between regardless of change in electrical angle. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a generator used for a bicycle hub dynamo, a small wind power generator, and the like.

  In a bicycle hub dynamo, the rotor rotates at the same slow speed as that of the tire, so that the induced electromotive force at low speed tends to be insufficient. However, if the rotation of the tire is increased with a gear and the rotor is rotated, the structure of the generator is complicated and the gear noise increases.

  Therefore, in a synchronous generator used in a hub dynamo, as shown in FIG. 11, by using multiple poles (4 poles and 24 slots in FIG. 11), cogging torque is reduced and sufficient induced electromotive force is generated even at low speeds. I am trying to get it. In this synchronous generator, a cylindrical permanent magnet 4 is arranged on the outer peripheral surface of the rotor 1, a number of slots are formed in the stator 2 around the rotor 1, and a coil 3 is wound around each slot.

  However, since the permanent magnet 4 of the synchronous generator needs to be multipolarized so that the magnetic poles N / S appearing on the cylindrical outer surface are alternately switched along the circumferential direction, the magnetic force is strong but anisotropic. Rare earth sintered magnets or the like, which must be used, and bond magnets (plastic magnets) with weak magnetic force must be used. Further, when the number of poles is increased, it is necessary to wind a large number of coils 3 in a fine slot, so that the generator manufacturing process becomes complicated. In addition, these circumstances are not limited to the synchronous generator shown in FIG. 11, but the same applies to the case of a claw-pole type synchronous generator that has been widely used recently as a hub dynamo.

  For this reason, the conventional synchronous generator used in the conventional hub dynamo has a problem that since the magnetic force of the permanent magnet 4 is weak, the change in the interlinkage magnetic flux of the coil 3 is reduced, and a large induced electromotive force cannot be obtained. It was. Moreover, since the winding operation of the coil 3 is complicated and troublesome, there is a problem that the manufacturing cost increases.

  As shown in FIG. 12, coils 3 and 3 are wound around two stators 2 and 2 that are closely fixed to both magnetic pole surfaces of the permanent magnet 4, and a rotor is formed on the tip surfaces of these stators 2 and 2. 2. Description of the Related Art Conventionally, there has been proposed a generator that solves the above problem by bringing one pole tooth 1a closer (see, for example, Patent Document 1).

However, in this generator, as shown in FIG. 12A, when the pole teeth 1a of the rotor 1 approach the stators 2 and 2, the magnetic flux passes in one direction through a narrow gap, and FIG. As shown in (b), when the pole teeth 1a of the rotor 1 are separated from the stators 2 and 2, the magnetic flux passes in the opposite direction only by repeating the two cases of the case where the magnetic flux does not pass through the wide gap. Therefore, the change in magnetic flux interlinking with the coils 3 and 3 is also reduced. Moreover, as shown in FIG. 12B, when the pole teeth 1a of the rotor 1 are separated from the stators 2 and 2, leakage magnetic flux is generated in the vicinity of the gap and the magnetic flux cannot be completely blocked. The change in linkage flux is further reduced. Therefore, although this generator can use the permanent magnet 4 having a strong magnetic force, the problem that the flux linkage change cannot be made sufficiently large and a large induced electromotive force cannot be obtained arises. It was.
JP-A-11-98797

  The present invention intends to provide a generator capable of obtaining a large induced electromotive force by effectively utilizing a permanent magnet having a strong magnetic force by alternately switching a magnetic path through which a magnetic flux by two or more permanent magnets passes. Is.

  The generator according to claim 1 is a first core in which pole teeth are formed, and a second core in which pole teeth are respectively formed in two sets of pole teeth portions, and each set of poles with respect to the pole teeth of the first core. The second core is configured so that the gaps of the pole teeth in the two sets of pole teeth are alternately switched by changing the electrical angle by moving the teeth close to each other and moving relatively. A coil wound between two pairs of pole teeth, and two or more permanent magnets having magnetic pole faces of the same polarity in close contact with the vicinity of each pair of pole teeth in the second core; Two auxiliary cores are provided that are closely fixed to the magnetic pole surface of the other polarity of the magnet and that always approach the first core with a narrow gap regardless of changes in electrical angle.

  The generator according to claim 2 is configured such that the auxiliary core always approaches the pole teeth of the first core with a narrow gap, and the surface of the auxiliary core that approaches the pole teeth of the first core is connected to the pole teeth of the first core. It is characterized in that an unevenness in which a narrow gap between them slightly changes is formed.

  According to the first aspect of the present invention, by the relative movement with the first core, the width of the gap between the two pairs of pole teeth of the second core is alternately switched, and a permanent magnet having the same polarity is provided in the vicinity of these pole teeth. Are closely fixed, so that magnetic fluxes in opposite directions alternately pass between the two sets of pole teeth of the second core. Therefore, since the magnetic flux linked to the coil wound between the two sets of pole teeth of the second core repeatedly changes, an induced electromotive force can be obtained.

  In addition, since each permanent magnet does not need to be multipolar magnetized, a large induced electromotive force can be obtained using a magnet having a strong magnetic force. Also, the configuration of the pole teeth allows the flux linkage to be changed by a slight relative movement between the first core and the second core, so there is no need to increase the number of poles, and the coil winding operation can be complicated. Therefore, an increase in manufacturing cost can be suppressed.

  Furthermore, since the magnetic flux in the opposite direction is alternately linked to the coil from the two permanent magnets, the induced electromotive force can be further increased. In addition, the gaps between the two pairs of pole teeth of the second core are alternately switched from wide to narrow, and both do not widen, so that the induced electromotive force is not reduced by the leakage magnetic flux.

  The first core, the second core, and the auxiliary core are preferably made of at least a ferromagnetic material and are preferably a soft magnetic material. Moreover, since the 1st core and the 2nd core should just move relatively, there is a case where one is a fixed core (stator) and the other moves, and a case where both move. . Here, if one side is a stator, the other is a rotor when the other is rotationally moved, and the other is a slider when the other is linearly moved. A pole tooth is a part in which one or more irregularities are formed in the core. When the pole teeth of the first core and the second core approach each other, the gap becomes narrower if the convex parts face each other. If the recesses face each other, the gap becomes wider. The shape of the convex portion of the pole teeth can be an arbitrary shape such as a spur gear shape that is bent in a dogleg shape, in addition to a spur gear shape along the rotation axis. In addition, the pole teeth of the first core are usually composed of a large number of irregularities, and in the case of the rotational movement type, they are usually formed in an endless shape.

  According to the invention of claim 2, since the unevenness is formed in the auxiliary core, the narrow gap between the first core and the pole teeth can be slightly changed according to the change in the electrical angle. Thus, the cogging torque can be suppressed.

  Hereinafter, the best embodiment of the present invention will be described with reference to FIGS. In these drawings, the same reference numerals are given to the constituent members having the same functions as those of the conventional example shown in FIGS.

[First Embodiment]
In order to explain the principle of operation, the generator of this embodiment shows a model that makes it easy to understand the change in the magnetic path on a two-dimensional drawing. As shown in FIG. 1, this generator is an out-rotor type in which a rotor 1 (first core) rotates around a stator 2 (second core).

  The rotor 1 is made of a cylindrical soft magnetic material, and a large number of concavities and convexities of the pole teeth 1a are formed in an internal gear shape on the inner peripheral surface. Since FIG. 1 shows the case where the pole teeth 1a are composed of 21 convex portions, the electrical angle has changed by 360 ° by rotating the rotor 1 by about 17 ° (≈360 ° / 21). become.

  The stator 2 is made of a soft magnetic material having a long bar shape or a thick plate shape, and pole teeth 2a and 2b are formed on two sets of pole tooth portions at both ends in the vertical direction. Each pole tooth 2a, 2b consists of two convex parts and a concave part between them, and the pole tooth 1a on the inner peripheral surface of the rotor 1 rotates while circumscribing through a wide and narrow gap. Yes. Further, as shown in FIG. 1, when the rotational position of the rotor 1 is an electrical angle of 0 °, the convex portion of the lower pole tooth 2b faces the convex portion of the pole tooth 1a of the rotor 1 through a narrow gap. The convex portion of the upper pole tooth 2a faces the concave portion of the pole tooth 1a of the rotor 1 through a wide gap. When the electrical angle is 180 ° shown in FIG. Of the pole teeth 1a of the rotor 1 through a narrow gap, while the protrusion of the lower pole teeth 2b faces the recess of the pole teeth 1a of the rotor 1 through a wide gap. As the angle changes, the gaps between the pole teeth 2a and 2b at both ends of the stator 2 are alternately switched.

  As shown in FIG. 1, the stator 2 has two permanent magnets 4 and 5 closely fixed to the side surfaces near the pole teeth 2a and 2b at both ends. The permanent magnets 4 and 5 are single-pole magnetized magnets in which the surface in close contact with the side surface of the stator 2 is an N-pole magnetic pole surface and the opposite surface is an S-pole magnetic pole surface. An anisotropic rare earth sintered magnet or the like can be used. Also, here, one permanent magnet 4 is closely fixed to the right side surface of the stator 2 near the upper pole tooth 2a, and the other permanent magnet 5 is closely contacted to the left side surface of the stator 2 near the lower pole tooth 2b. It is fixed.

  Auxiliary cores 6 and 7 are fixed in close contact with the magnetic pole surfaces of the S poles of the permanent magnets 4 and 5, respectively. The auxiliary cores 6 and 7 are made of a soft magnetic material, and the surface different from the surface fixed to the permanent magnets 4 and 5 is any one of two or three of the pole teeth 1a of the rotor 1 regardless of the change in the electrical angle. The projection is inscribed through a narrow gap at all times.

  A coil 3 is wound around the center of the stator 2 in the vertical direction. Therefore, when the magnetic flux Φ passing through the stator 2 changes, an induced electromotive force corresponding to the change is generated in the coil 3.

  When the electrical angle shown in FIG. 1 is 0 ° as shown in FIG. 1, only the pole teeth 2b below the stator 2 approach the pole teeth 1a of the rotor 1 through a narrow gap. The reluctance of the magnetic path between the rotor 1 and the rotor 1 is very large at the top and very small at the bottom. For this reason, the magnetic flux Φ from the upper permanent magnet 4 reaches the rotor 1 downward from the upper part of the stator 2, and the original permanent magnet 4 via the pole teeth 1 a of the rotor 1 and the upper auxiliary core 6. Return to. Further, the magnetic flux Φ from the lower permanent magnet 5 reaches the rotor 1 downward from the lower portion of the stator 2, and is transferred to the original permanent magnet 5 through the pole teeth 1 a of the rotor 1 and the lower auxiliary core 7. Return. Accordingly, the downward magnetic flux Φ from the upper permanent magnet 4 is linked to the coil 3.

  Next, when the electrical angle is 90 ° shown in FIG. 2, the upper and lower pole teeth 2a and 2b of the stator 2 approach the pole teeth 1a of the rotor 1 through a narrow gap in about half of the convex portion. The magnetic resistance of the magnetic path between the stator 2 and the rotor 1 is reduced to some extent both vertically. Therefore, the magnetic flux Φ from the upper permanent magnet 4 reaches the rotor 1 upward from the upper portion of the stator 2, and the original permanent magnet 4 via the pole teeth 1 a of the rotor 1 and the upper auxiliary core 6. Return to. Further, the magnetic flux Φ from the lower permanent magnet 5 reaches the rotor 1 downward from the lower portion of the stator 2, and is transferred to the original permanent magnet 5 through the pole teeth 1 a of the rotor 1 and the lower auxiliary core 7. Return. Therefore, the magnetic flux Φ from any of the upper and lower permanent magnets 4 and 5 is not linked to the coil 3.

  Further, when the electrical angle is 180 ° shown in FIG. 3, only the pole teeth 2 a above the stator 2 approach the pole teeth 1 a of the rotor 1 through a narrow gap. The magnetic resistance of the magnetic path is very small at the top and very large at the bottom. Therefore, the magnetic flux Φ from the lower permanent magnet 5 reaches the rotor 1 upward from the lower part of the stator 2, and the original permanent magnet 5 via the pole teeth 1 a of the rotor 1 and the lower auxiliary core 7. Return to. Further, the magnetic flux Φ from the upper permanent magnet 4 reaches the rotor 1 upward from the upper portion of the stator 2, and is transferred to the original permanent magnet 4 through the pole teeth 1 a of the rotor 1 and the upper auxiliary core 6. Return. Therefore, the upward magnetic flux Φ from the lower permanent magnet 5 is linked to the coil 3.

  Further, when the electrical angle is 270 ° shown in FIG. 4, both the upper and lower pole teeth 2a and 2b of the stator 2 approach the pole tooth 1a of the rotor 1 through a narrow gap at about half of the convex portion. The magnetic resistance of the magnetic path between the stator 2 and the rotor 1 is reduced to some extent both vertically. Therefore, the magnetic flux Φ from the upper permanent magnet 4 reaches the rotor 1 upward from the upper portion of the stator 2, and the original permanent magnet 4 via the pole teeth 1 a of the rotor 1 and the upper auxiliary core 6. Return to. Further, the magnetic flux Φ from the lower permanent magnet 5 reaches the rotor 1 downward from the lower part of the stator 2, and is transferred to the original permanent magnet 5 through the pole teeth 1 a of this rotor 1 and the lower auxiliary core 7. Return. Therefore, the magnetic flux Φ from any of the upper and lower permanent magnets 4 and 5 is not linked to the coil 3.

  The generator repeats the operations shown in FIGS. 1 to 4 as the rotor 1 rotates, so that the magnetic flux Φ interlinked with the coil 3 has an electrical angle of 0 ° and an electrical angle of 180 as shown in FIG. It changes in a reverse sine wave shape at the angle of °, and an alternating induced electromotive force is generated in the coil 3 with the change of the magnetic flux Φ.

  According to the above configuration, since it is not necessary to magnetize the permanent magnets 4 and 5, a large induced electromotive force can be obtained by using a rare earth sintered magnet having a strong magnetic force. Further, since the coil 3 only needs to be wound around the center portion of the stator 2, the winding operation is not complicated, and an increase in manufacturing cost can be suppressed.

  Further, since the magnetic flux Φ in the opposite direction is alternately linked to the coil 3 from the two permanent magnets 4 and 5, the induced electromotive force is larger than that in the case where the magnetic flux Φ is merely repeatedly passed and cut off in one direction. Can be obtained. In addition, the gap between the upper and lower pole teeth 2a and 2b of the stator 2 is alternately switched between wide and narrow, and the magnetic resistance is always reduced, so that the induced electromotive force is not reduced by the leakage magnetic flux.

  In the first embodiment, as shown in FIG. 6, unevenness in which a narrow gap between the auxiliary teeth 6 and 7 and the pole teeth 1 a of the auxiliary cores 6 and 7 approaches the pole teeth 1 a slightly changes. 6a and 7a are formed. These irregularities 6a and 7a are in such a positional relationship that the cogging torque generated between the pole teeth 1a of the rotor 1 and the pole teeth 2a and 2b of the stator 2 is canceled between the pole teeth 1a of the rotor 1. Is formed. Therefore, since the cogging torque is reduced in the generator according to the first embodiment, when it is used for small wind power generation, the rotor 1 can be rotated to generate power even with a small amount of wind. Even when used as a hub dynamo, the pedaling force can be reduced.

  In the first embodiment, the pole teeth 2a and 2b of each pair of pole teeth of the stator 2 are each composed of two protrusions. However, these may be only one protrusion. It can also be formed with three or more convex portions, and may be different for each pole tooth portion. Furthermore, in the first embodiment, the case where one pole tooth portion of the first set is provided at the upper end of the stator 2 and one pole tooth portion of the second set is provided at the lower end is shown. If the pole tooth portion is provided, each pair of pole tooth portions may be separated into two or more places.

  Furthermore, although the case where two permanent magnets 4 and 5 are used is shown in the first embodiment, the number of permanent magnets is not limited as long as it is two or more. For example, the permanent magnet is permanently attached to the right side surface above the stator 2. The magnet 4 is fixed in close contact, and another permanent magnet is also fixed in close contact with the left side surface. The permanent magnet 5 is fixed in close contact with the lower left side surface of the stator 2, and another permanent magnet is also fixed in close contact with the right side surface. In addition, an auxiliary core can be tightly fixed to each added permanent magnet.

[Second Embodiment]
This embodiment shows the generator actually used as a bicycle hub dynamo. As shown in FIGS. 7 to 9, this generator is also of an out-rotor type in which the rotor 1 (first core) rotates around the stator 2 (second core).

  The rotor 1 is made of a cylindrical soft magnetic material, and a large number of concavities and convexities of the pole teeth 1a are formed in an internal gear shape on the inner peripheral surface. The stator 2 is made of a cylindrical soft magnetic material, and two sets of pole teeth are provided on the outer peripheral surface in the axial direction. Each pole tooth portion is a portion in which the irregularities of the pole teeth 2a and 2b are formed in a number of external gears over the entire circumference. The pole teeth 2a of the first set of pole teeth shown on the left side of FIG. 7 and the pole teeth 2b of the second set of pole teeth shown on the right side of FIG. As shown in the B-B cross section, the phase of the concavities and convexities is formed with an electrical angle shifted by 180 °.

  As shown in FIG. 7, the stator 2 has permanent magnets 4 and 5 firmly fixed to both left and right end surfaces in the axial direction. The permanent magnets 4 and 5 are single-pole magnetized magnets in which the surface closely contacting the end surface of the stator 2 is an N-pole magnetic pole surface and the opposite surface is an S-pole magnetic pole surface. An anisotropic rare earth sintered magnet or the like can be used.

  Auxiliary cores 6 and 7 are fixed in close contact with the magnetic pole surfaces of the S poles of the permanent magnets 4 and 5, respectively. The auxiliary cores 6 and 7 are made of a disk-shaped soft magnetic material with no irregularities on the outer peripheral surface, and this outer peripheral surface always has a narrow gap with the inner peripheral surface of the left and right end portions of the rotor 1 regardless of changes in the electrical angle. It is intended to be inscribed through. In addition, if the irregularities 6a and 7a as shown in FIG. 6 are formed on the outer peripheral surfaces of these auxiliary cores 6 and 7, pole teeth are formed on the inner peripheral surfaces of the left and right ends of the rotor 1. Cogging torque can be reduced.

  A coil 3 is wound around a central portion in the stator 2 in the axial direction (a central portion in the left-right direction in FIG. 7). In other words, the coil 3 is wound around the outer periphery of a bobbin-shaped portion in which the stator 2 is recessed at the center with the rotating shaft of the generator as a center. When changed, an induced electromotive force corresponding to the change is generated in the coil 3.

  When the electrical angle shown in FIG. 7 is 0 ° as shown in FIG. 7, only the left pole tooth 2a of the stator 2 approaches the pole tooth 1a of the rotor 1 through a narrow gap. The magnetic resistance of the magnetic path with the rotor 1 is very small on the left side and very large on the right side. For this reason, the magnetic flux Φ from the right permanent magnet 5 reaches the rotor 1 via the pole teeth 2a from the right end of the stator 2 toward the left and upward on the left, and to the right end of the rotor 1 and the right side. Return to the original permanent magnet 5 through the auxiliary core 7. Further, the magnetic flux Φ from the left permanent magnet 4 reaches the rotor 1 immediately from the left end of the stator 2 via the pole teeth 2a, and the left end of the rotor 1 and the left auxiliary core 6 are connected to each other. Return to the original permanent magnet 4. Therefore, a leftward magnetic flux Φ from the right permanent magnet 5 is linked to the coil 3.

  Next, when the electrical angle is 180 ° shown in FIG. 10, only the pole tooth 2 b on the right side of the stator 2 approaches the pole tooth 1 a of the rotor 1 through a narrow gap. The magnetoresistance of the magnetic path between them is very small on the right side and very large on the left side. For this reason, the magnetic flux Φ from the left permanent magnet 4 is directed from the left end of the stator 2 to the right and upward on the right side to reach the rotor 1 via the pole teeth 2b. Return to the original permanent magnet 4 through the auxiliary core 6. Further, the magnetic flux Φ from the right permanent magnet 5 reaches the rotor 1 immediately from the right end of the stator 2 via the pole teeth 2b, and the right end of the rotor 1 and the right auxiliary core 7 are connected to each other. Return to the original permanent magnet 5. Accordingly, the right magnetic flux Φ from the left permanent magnet 5 is linked to the coil 3.

  Furthermore, when the electrical angle is 90 ° and 270 °, the left and right pole teeth 2a and 2b of the stator 2 approach the pole teeth 1a of the rotor 1 through a narrow gap in about half of the convex portion. The magnetic resistance of the magnetic path between the stator 2 and the rotor 1 is reduced to some extent on both the left and right sides. Therefore, the magnetic flux Φ from the left and right permanent magnets 4 and 5 returns from the rotor 1 to the original permanent magnets 4 and 5 through the nearest auxiliary cores 6 and 7, respectively. The magnetic flux Φ from the magnets 4 and 5 will not be linked.

  The generator repeats the operations of FIGS. 7 and 10 as the rotor 1 rotates, so that the magnetic flux Φ interlinked with the coil 3 has an electrical angle of 0 ° and an electrical angle as shown in FIG. When it is 180 °, it changes in a reverse sine wave shape, and an alternating induced electromotive force is generated in the coil 3 with the change of the magnetic flux Φ.

  According to the above configuration, since it is not necessary to magnetize the permanent magnets 4 and 5, a large induced electromotive force can be obtained by using a rare earth sintered magnet having a strong magnetic force. Further, since the coil 3 only needs to be wound around the center portion of the stator 2, the winding operation is not complicated, and an increase in manufacturing cost can be suppressed.

  Further, since the magnetic flux Φ in the opposite direction is alternately linked to the coil 3 from the two permanent magnets 4 and 5, the induced electromotive force is larger than that in the case where the magnetic flux Φ is merely repeatedly passed and cut off in one direction. Can be obtained. In addition, the gap between the left and right pole teeth 2a, 2b of the stator 2 is alternately switched between wide and narrow, and one of the magnetic resistances is always reduced, so that the induced electromotive force is not reduced by the leakage magnetic flux.

  In the first and second embodiments, the case where the N-pole magnetic pole surfaces of the permanent magnets 4 and 5 are closely fixed to the stator 2 has been described. The pole face of the S pole may be tightly fixed to the stator 2.

  In the first and second embodiments, the case where soft magnetic materials are used for the rotor 1, the stator 2, and the auxiliary cores 6 and 7 in order to reduce hysteresis loss (iron loss) has been described. It is preferable to use a soft magnetic material with little eddy current loss, such as a magnetic core (sintered soft magnetic material) or a laminated body of insulating thin steel plates. Conversely, if these hysteresis loss and eddy current loss are not particularly problematic, an arbitrary ferromagnetic material can be used.

  In the first and second embodiments, the out-rotor type generator is shown. However, the same applies to the in-rotor type generator, and the slider performs linear movement, swing movement, and the like with respect to the stator. The same can be applied to such a generator. In the first and second embodiments, the case where the permanent magnets 4 and 5 are closely fixed and the second core around which the coil 3 is wound is used as the stationary stator is shown. It is also possible to use a rotating rotor or a slider that performs linear / oscillating movement.

1 is a longitudinal sectional view showing a first embodiment of the present invention and perpendicular to the axial direction of a generator (electrical angle 0 °). BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view illustrating a first embodiment of the present invention and perpendicular to an axial direction of a generator (electrical angle: 90 °). 1 shows a first embodiment of the present invention and is a vertical cross-sectional view perpendicular to the axial direction of a generator (electrical angle 180 °). FIG. 1 shows a first embodiment of the present invention and is a vertical cross-sectional view perpendicular to the axial direction of a generator (electrical angle 270 °). FIG. It is a figure which shows the 1st Embodiment of this invention and shows the relationship of the linkage magnetic flux with respect to the change of an electrical angle. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an enlarged vertical cross-sectional view illustrating a first embodiment of the present invention and illustrating a surface in which irregularities for reducing cogging torque are formed on an auxiliary core. The 2nd Embodiment of this invention is shown, Comprising: It is a longitudinal cross section along the axial direction in the upper part of a generator (electrical angle 0 degree). FIG. 9 shows a second embodiment of the present invention and is a cross-sectional view taken along line AA in FIG. 7. FIG. 8 shows a second embodiment of the present invention and is a cross-sectional view taken along the line BB in FIG. 7. The 2nd Embodiment of this invention is shown, Comprising: It is a longitudinal cross section along the axial direction in the upper part of a generator (electrical angle 180 degrees). It is a longitudinal cross-sectional view which shows a prior art example and is perpendicular | vertical to the axial direction of a synchronous generator. It is a sectional view of a generator used for a hub dynamo, showing a conventional example.

Explanation of symbols

1 rotor 1a pole tooth 2 stator 2a pole tooth 2b pole tooth 3 coil 4 permanent magnet 5 permanent magnet 6 auxiliary core 6a unevenness 7 auxiliary core 7a unevenness

Claims (2)

A first core formed with pole teeth;
A second core having pole teeth formed in two sets of pole teeth, respectively, by moving the pole teeth of each set of pole teeth closer to the pole teeth of the first core, As the angle changes, the width of the gap between the pole teeth in the two pairs of pole teeth is alternately switched,
A coil wound between two sets of pole teeth in the second core;
Two or more permanent magnets having magnetic pole faces of the same polarity in close contact and fixed in the vicinity of each pair of pole teeth in the second core;
A generator comprising: two auxiliary cores that are closely fixed to a magnetic pole surface of the other polarity of each permanent magnet and that always approach the first core with a narrow gap regardless of a change in electrical angle. .   The auxiliary core always approaches the pole teeth of the first core with a narrow gap, and the narrow gap between the pole teeth slightly changes on the surface of the auxiliary core that approaches the pole teeth of the first core. The generator according to claim 1, wherein unevenness is formed.

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