Axial gap type rotating electric machine

Abstract

An axial gap rotating electric machine is provided that can suppress iron loss and achieve high efficiency even at high rotational speeds, and further can suppress high production costs. [Solution] An axial gap type rotating electric machine having a stator and a rotor rotatably assembled to the stator with an air gap in the axial direction, wherein the stator has a circular portion and p claw poles protruding radially from the circular portion, a pair of claw pole members arranged with a predetermined gap in the axial direction, and a unit stator in which an annular coil is sandwiched axially within the circular portion, the rotor is inserted into the gap and has a disk-shaped magnet on the front side magnetized or magnetically arranged with 2p poles alternating north and south poles in the circumferential direction, and on the back side magnetized or magnetically arranged with 2p poles alternating north and south poles in the circumferential direction, and magnetic flux coming out from the front side of the disk-shaped magnet enters through the opposing claw pole, interlinks with the annular coil, and forms a closed magnetic path returning to the disk-shaped magnet via the opposing claw pole on the back side.

Description

[Technical Field]

[0001] The present invention relates to an axial gap rotating electric machine used as an electric motor or a generator. [Background technology]

[0002] There is a strong market demand for rotating electrical machines to be lighter, thinner, shorter, and smaller, and recently, there has been an increasing demand for energy saving and high efficiency as a measure against global warming. There is also a strong demand for low vibration, low noise, and low cost.

[0003] There are various types of rotating electric machines known, but among them, the toroidal coil type has been attracting attention in recent years because three-phase types are more efficient and have vibration advantages than two-phase types, the number of coils can be reduced with toroidal coil types compared to concentrated winding or distributed winding, the structure is simple and inexpensive because there is no need for iron core slots, and there are no coil ends and the winding factor is high, which is advantageous for making the rotating electric machine smaller.

[0004] Conventional brushless DC motors (hereafter referred to as "BLDCMs" in this specification) use permanent magnets in the rotor and laminated silicon steel stator cores, with three-phase configurations being the norm for efficiency and low vibration. Conventional BLDCMs use distributed winding coils for applications where low vibration is important, and concentrated winding coils for applications where low cost and efficiency are important. This is because distributed winding coils have sinusoidal magnetic flux distribution, resulting in low vibration, but the large coil ends increase copper loss and reduce efficiency. Both distributed and concentrated winding coils have the common problem of complex structure, as they require the coils to be wound into slots in the stator core.

[0005] On the other hand, if a toroidal coil type is adopted, the problems associated with distributed winding and concentrated winding coils can be solved. As an example, the rotating electric machines described in Patent Document 1 and Non-Patent Document 1 are known, and are mass-produced for practical use in stepping motors (hereinafter referred to as "STM" in this specification). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 07-227075 [Non-Patent Document 1] Improvement of PM Stepping Motor Characteristics, 1993, Japan Management Association, Motor Technology Symposium, 2-2-1 Summary of the Invention [Problem to be solved by the invention]

[0007] However, while this toroidal coil type three-phase rotating electric machine is not a problem when used as an STM with a rotation speed of several hundred RPM, which is primarily intended for positioning purposes, when used as a BLDCM, which is primarily used to obtain power, the rotation speed reaches several thousand RPM, which increases iron loss, mainly due to eddy current loss, and causes problems with reduced efficiency.

[0008] More specifically, as shown in Fig. 8, a conventional three-phase toroid coil STM includes a stator having a U-phase claw pole 40. The stator includes a stator 41 including a U-phase toroid coil, a stator 42 including a V-phase toroid coil, and a stator 43 including a W-phase toroid coil. The stator also includes a rotor 44 that is rotatably disposed with an air gap in the radial direction relative to the stator. Rotor 44 has multiple permanent magnets arranged on its outer periphery, and the multiple permanent magnets are alternately arranged so that the polarities on the surface of adjacent permanent magnets are north, south, and north. Note that Fig. 8 shows stators 41-43 in an exploded view to explain the positional relationship between rotor 44 and claw poles 40.

[0009] A plurality of claw poles 40 are arranged on the surfaces of stator 41 including a U-phase toroid coil, stator 42 including a V-phase toroid coil, and stator 43 including a W-phase toroid coil, facing rotor 44. Adjacent claw poles 40 are arranged with a misalignment angle θ, which is an electrical angle of 60° or 120°. Each claw pole 40 is formed by stamping or bending electromagnetic steel sheet. Therefore, conventional claw poles 40 have a large iron loss and a low rotational speed, making them difficult to use in practical BLDCMs with high rotational speeds.

[0010] 9 is an orthogonal cross-sectional view of one phase of the claw poles in FIG. 8, in which two adjacent claw poles 40 face adjacent north and south poles of the rotor, and a circumferential gap g must be provided between the claw poles to suppress leakage flux between the adjacent claw poles 40. As a result, in conventional claw-pole rotating electric machines, the leakage flux permeance P across the circumferential gap g between the claw poles is calculated as P = μS / g. Therefore, since the claw poles 40 are rectangular, the facing area S between adjacent claw poles 40 is large, and the gap g must be large. As a result, the need to ensure the circumferential gap g poses a problem in that the facing area S between the claw poles 40 and the rotor 44 in the air gap direction (circumferential width b × axial length of the claw poles 40) cannot be increased.

[0011] As described above, the claw poles of conventional claw-pole rotating electric machines were manufactured by stamping or bending electromagnetic steel sheets, making it impossible to create complex shapes other than rectangular. As a result, the effective tooth width ratio k of conventional claw poles 40 was k = b / a, and the effective claw pole area was approximately 70% of the rotor magnetic pole area, which posed a problem in that the flux linkage could not be increased accordingly.

[0012] Furthermore, although the rotating electrical machine shown in FIG. 8 is a radial gap type rotating electrical machine, an axial gap type rotating electrical machine also has the same problem.

[0013] Therefore, the present invention has been made to solve the above problems, and aims to provide an axial gap type rotating electric machine that can suppress iron loss and achieve high efficiency even at high rotational speeds, and further suppress high production costs, compared to conventional axial gap type rotating electric machines. [Means for solving the problem]

[0014] The axial gap rotating electric machine of the present invention, which solves the above-mentioned problems, is an axial gap rotating electric machine having a stator and a rotor rotatably assembled to the stator with an air gap in the axial direction, wherein the stator has a circular portion and p claw poles protruding radially from the circular portion, a pair of claw pole members arranged with a predetermined gap in the axial direction, and a unit stator in which an annular coil is sandwiched axially within the circular portion, and the rotor is inserted into the gap and has a disk-shaped magnet on its front side magnetized or magnetically arranged with 2p poles alternating north and south poles in the circumferential direction and its back side magnetized or magnetically arranged with 2p poles alternating north and south poles in the circumferential direction, and magnetic flux leaving the front side of the disk-shaped magnet enters through the opposing claw pole, interlinks with the annular coil, and returns to the disk-shaped magnet via the opposing claw pole on the back side, forming a closed magnetic path.

[0015] In the axial gap rotating electric machine according to the present invention, it is preferable that the front and back surfaces of the disk-shaped magnet are magnetized with opposite polarities, and the claw poles of the pair of claw pole members are arranged in the same phase in the circumferential direction.

[0016] In the axial gap rotating electric machine according to the present invention, it is preferable that the front and back surfaces of the disk-shaped magnet are magnetized to have the same polarity, and the claw poles of the pair of claw pole members are arranged with a phase difference of a predetermined electrical angle in the circumferential direction.

[0017] Furthermore, in the axial gap type rotating electric machine according to the present invention, it is preferable that the disk-shaped magnet has an equivalent magnet magnetization effective length longer than the thickness of the disk-shaped magnet by aligning the magnetic field diagonally from the axial direction across the front and back of the magnet.

[0018] In the axial gap rotating electric machine according to the present invention, it is preferable that a plurality of the stator units are stacked in phase in the axial direction.

[0019] In addition, in the axial gap type rotating electric machine according to the present invention, it is preferable that either the unit stators arranged in a stacked phase configuration or the disk-shaped magnets facing the unit stators are arranged with a circumferential shift of a predetermined electrical angle.

[0020] In the axial gap rotating electric machine according to the present invention, it is preferable that the annular coil is provided inside the disk-shaped magnet.

[0021] In the axial gap rotating electric machine according to the present invention, it is preferable that the shape of the claw poles is such that the thickness of the claw poles on the side opposite the air gap that does not face the disk-shaped magnet gradually tapers radially from the base to the tip.

[0022] In the axial gap rotating electric machine according to the present invention, it is preferable that the claw poles are thick at the tooth width center on the air gap side and thin circumferentially toward the tooth end portions.

[0023] In the axial gap rotating electric machine according to the present invention, it is preferable that the claw pole members are formed of powder iron cores.

[0024] The above summary of the invention does not list all of the necessary features of the present invention, and subcombinations of these features may also constitute inventions. [Effects of the Invention]

[0025] According to the axial gap rotating electric machine of the present invention, multiple claw poles are formed radially protruding from an annular portion, and a toroidal coil is sandwiched between a pair of claw pole members, with a predetermined gap between the claw poles. A disc-shaped magnet of the rotor is inserted into the gap between the claw poles, and magnetic flux exiting the front side of the disc-shaped magnet enters the opposing claw pole, interlinks with the toroidal coil, and returns to the disc-shaped magnet via the opposing claw pole on the back side, forming a closed magnetic path. This minimizes leakage flux, increases flux linkage, and produces high torque. Furthermore, the stator can be formed using a powder iron core, reducing iron loss and increasing the winding factor, resulting in high efficiency. Furthermore, the use of a toroidal coil structure allows for the provision of an axial gap rotating electric machine at a lower cost than conventional laminated structures. Furthermore, the axial gap rotating electric machine of the present invention is robust, allows for improved assembly precision, and allows for optimal use of powder iron cores and reduced weight. [Brief explanation of the drawings]

[0026] [Figure 1] 1 is a partial cross-sectional view showing an axial gap rotating electric machine according to an embodiment of the present invention; [Figure 2] 1 is an axial cross-sectional view of an axial gap rotating electric machine according to an embodiment of the present invention; [Figure 3] 1 is a perspective view of a pair of claw pole members used in an axial gap rotating electric machine according to an embodiment of the present invention; [Figure 4] FIG. 2 is a perspective view of a claw pole member used in the axial gap rotating electric machine according to the embodiment of the present invention. [Figure 5] FIG. 10 is a diagram showing a modified example of an axial gap rotating electric machine according to an embodiment of the present invention. [Figure 6]FIG. 2 is a diagram showing the positional relationship between a disk-shaped magnet and claw poles used in the axial gap rotating electric machine according to the embodiment of the present invention. [Figure 7] 10A and 10B are diagrams showing modified examples of the positional relationship between the disk-shaped magnets and the claw poles used in the axial gap rotating electric machine according to the embodiment of the present invention. [Figure 8] FIG. 10 is a partial cross-sectional view showing a conventional rotating electric machine. [Figure 9] FIG. 10 is a diagram illustrating a conventional claw pole. [Figure 10] FIG. 1 is a diagram illustrating a conventional cylindrical magnet having a U-shaped magnetic path. DETAILED DESCRIPTION OF THE INVENTION

[0027] Preferred embodiments for carrying out the present invention will be described below with reference to the drawings. Note that the following embodiments do not limit the inventions according to the claims, and not all of the combinations of features described in the embodiments are necessarily essential to the solution of the invention.

[0028] FIG. 1 is a partial cross-sectional view showing an axial gap rotating electric machine according to an embodiment of the present invention, FIG. 2 is an axial cross-sectional view of an axial gap rotating electric machine according to an embodiment of the present invention, FIG. 3 is a perspective view of a pair of claw pole members used in an axial gap rotating electric machine according to an embodiment of the present invention, FIG. 4 is a perspective view of a claw pole member used in an axial gap rotating electric machine according to an embodiment of the present invention, FIG. 5 is a diagram showing a modified example of an axial gap rotating electric machine according to an embodiment of the present invention, FIG. 6 is a diagram showing the positional relationship between a disk-shaped magnet and a claw pole used in an axial gap rotating electric machine according to this embodiment of the present invention, and FIG. 7 is a diagram showing a modified example of the positional relationship between a disk-shaped magnet and a claw pole used in an axial gap rotating electric machine according to an embodiment of the present invention.

[0029] As shown in Figures 1 and 2, the axial gap type rotating electric machine 10 of this embodiment comprises a hollow cylindrical stator 11 and a rotor 12 that is rotatably assembled to the inner periphery of the stator 11 with an air gap in the axial direction.

[0030] The stator 11 has unit stators 11a to 11c arranged in a stacked fashion in the axial direction, with the unit stators 11a to 11c arranged in a stacked fashion so as to be circumferentially offset by a predetermined electrical angle (120° electrical angle in the three-phase axial gap rotating electric machine 10 according to this embodiment). The magnetic pole positions of the rotor 12 facing the unit stators 11a to 11c may be offset by 120° electrical angle. The outer periphery of the stator 11 is covered with a housing 23 made of a magnetic material, and brackets 27 are attached to both axial end faces as shown in FIG. 2. Bearings 26 are attached to the housing 23 and the bracket 27 to rotatably hold a shaft 24 of a rotor 32, which will be described later. To facilitate understanding of the structure of the axial gap rotating electric machine 10 according to this embodiment, the axial end faces of the housing 23, the bearings 26, and the bracket 27 are omitted in FIG. 1, and only the disc-shaped magnets of the rotor 12 are shown.

[0031] To facilitate understanding of the structure of the axial gap rotating electric machine 10 according to this embodiment, in FIG. 1, the stator units 11a to 11c are shown at the same position without being offset in the circumferential direction. In this case, the magnetic pole positions of the rotor 12 facing the stator units 11a to 11c are offset by 120° in electrical angle. FIG. 3 is a diagram showing the relationship between a pair of claw pole members 20 of the stator unit for one phase in FIG. 1, excluding the rotor. The two claw pole members 20, 20 are offset in the circumferential direction by one pole. This relationship diagram is for a high-torque configuration corresponding to FIG. 7, which will be described later.

[0032] As shown in FIG. 2, rotor 12 includes disk-shaped magnets 21 inserted into the gap between a pair of claw pole members 20 of each unit stator 11a to 11c, and disk-shaped magnets 21 are arranged at a predetermined interval via spacers 25, and disk-shaped magnets 21 are fixed to shaft 24.

[0033] 6, it is preferable that the front side of the disk-shaped magnet 21 is magnetized or magnetized with alternating north and south poles in the circumferential direction to form 2p poles, and the back side is magnetized with alternating north and south poles in the circumferential direction to form 2p poles.In addition to magnetizing the disk-shaped magnet 21, the disk-shaped magnet 21 may also be formed by arranging sector magnets in the circumferential direction and joining the sector magnets together.

[0034] The rotor 12 is arranged to be rotatable together with the axis of the shaft 24 relative to the stator 11 by a magnetic force generated by passing a current through the toroidal coil 22 .

[0035] Next, the unit stators 11a to 11c will be described. Since the unit stators 11a to 11c have the same shape, the unit stator 11a will be described, and descriptions of the unit stators 11b and 11c will be omitted.

[0036] The unit stator 11a includes a pair of claw pole members 20, 20 arranged with a predetermined gap in the axial direction so that a disk-shaped magnet 21 is rotatably arranged with an air gap in the axial direction, and an annular coil 22 wound around a bobbin 28 arranged to be sandwiched in the axial direction between annular portions 31 of the claw pole members 20, 20. As shown in Fig. 6, the claw poles 32 of the pair of claw pole members 20 are arranged at the same positions in the circumferential direction so as to face the disk-shaped magnet 21 at the same positions on the front and back. As will be described later, as shown in Fig. 7, the claw poles 32 may be arranged with a phase shift of one pole (180° in electrical angle).

[0037] 4, the claw pole member 20 is formed of a powder iron core and has a disk-shaped annular portion 31 and p claw poles 32 that protrude radially inward from the inner circumferential surface of the annular portion 31. The claw poles 32 are arranged approximately evenly, and between the claw poles 32, window portions 33 having approximately the same shape as the claw poles 32 are formed.

[0038] The claw pole 32 has a protrusion 34 that protrudes in one axial direction, and the protrusion 34 is formed to protrude in the axial direction further than the axial end face of the annular portion 31. The other axial end face of the claw pole 32 is formed flush with the annular portion 31.

[0039] The toroidal coil 22 is constructed by winding a wire around the axis of the bobbin 28, and is excellent in space saving because there are no coil ends as compared with concentrated winding or distributed winding.

[0040] 2, a housing 23 made of a magnetic material is attached to the outer circumferential surface and one end surface of the stator 11, and a bracket 27, also made of a magnetic material, is attached to the other end surface of the stator 11. A shaft 24 of the rotor 12 is rotatably supported via bearings 26 attached to the housing 23 and the bracket 27.

[0041] In the configuration of the axial gap rotating electric machine 10 according to this embodiment, as described above, the two claw pole members 20, 20 are not intermeshed but are arranged on both sides of the disk-shaped magnet 21, so no leakage magnetic flux is generated. Therefore, the tooth width of the claw pole 32 can be widened to the pole width of the disk-shaped magnet 21. As a result, the interlinkage magnetic flux is increased, and high torque is obtained.

[0042] If the claw pole member 20 is divided into two semicircular plates, the rotor 12 consisting of the three disk-shaped magnets 21, two spacers 25, and shaft 24 shown in Fig. 2 can be completed separately, and then the axial gap rotating electric machine 10 according to this embodiment can be assembled. Furthermore, since the claw pole member 20 is made of a pressed iron core, iron loss is reduced.

[0043] The axial gap rotating electric machine 10 according to this embodiment has been described as a so-called inner rotor type in which the rotor 12 is disposed on the inner periphery of the stator 11. The rotating electric machine according to this embodiment may also be configured as an outer rotor type axial gap rotating electric machine 10' in which a disk-shaped magnet rotates outward on the outer periphery of an annular coil, as shown in FIG.

[0044] 5 shows the rotor and stator configuration for one phase, and the configurations for the remaining two phases are omitted because they have the same configuration. The outer-rotor axial gap rotating electric machine 10' includes: a pair of claw pole members 20' each having p claw poles 32' extending radially outward from an annular portion 31'; a stator including an annular coil 22' wound around a bobbin 28' axially sandwiched between the annular portions 31' of the claw pole members 20'; and a rotor including a disk-shaped magnet 21' inserted between the claw poles 32', a spacer 36 that holds the disk-shaped magnet 21' in the axial direction, and a cylindrical rotating body 37 that holds the outer periphery of the spacer 36 and the disk-shaped magnet 21'.

[0045] Claw pole members 20' sandwich annular coil 22' and are fixed to a fixed shaft 35. The output of axial gap rotating electric machine 10' according to this embodiment is extracted from cylindrical rotating body 37. For example, if a tire is attached to the outer periphery of cylindrical rotating body 37, it can be configured as an in-wheel motor for an electric vehicle.

[0046] Furthermore, compared to the inner rotor type shown in Figures 1 and 2, this configuration allows the radius of the disk-shaped magnet 21' to be larger, resulting in a high torque output. Also, because the toroidal coil 22' is positioned on the inner diameter side, the average coil circumference of the windings wound around the toroidal coil 22' is shorter, making it possible to reduce the DC resistance of the toroidal coil 22' in each phase compared to the inner rotor type, reducing copper loss and promising higher efficiency.

[0047] Furthermore, the disk-shaped magnet 21' may be configured continuously in the circumferential direction. However, if the disk-shaped magnet 21' is divided into two parts, even in the case of a three-phase rotating electric machine, the rotor can be incorporated after the stator consisting of the UVW phases, which is made up of the claw pole member 20', the annular coil 22', and the fixed shaft 35, is completed, thereby completing the rotating electric machine.

[0048] When configuring a three-phase rotating electric machine as shown in Figures 4 and 5, the rotor magnetic pole positions may be the same for each phase, and the three unit stators may be shifted by a phase angle of 60° or 120° (electrical angle), or the three stators may be in the same position, and the three rotor magnetic pole positions may be shifted by 60° or 120° (electrical angle).

[0049] Modifications of the positions of the claw poles 32, 32′ and the magnetic poles of the disk-shaped magnets 21, 21′ will be further explained using FIGS. 6 and 7, which are explanatory diagrams common to both the outer rotor type and the inner rotor type, obtained by linearly expanding FIG. 1, which shows the inner rotor type axial gap rotating electric machine, and FIG. 5, which shows the outer rotor type axial gap rotating electric machine.

[0050] 6 shows a pair of claw poles 32 of a pair of claw pole members 20 arranged at the same positions in the circumferential direction so that the claw poles 32 face the disk-shaped magnet 21 at the same positions on the front and back of the disk-shaped magnet. That is, in FIG. 6, the disk-shaped magnet 21 is magnetized in the axial direction, so the magnetic poles on the front and back are opposite north and south poles as shown. Therefore, magnetic flux coming from the north pole on the front side of the magnet passes through the opposing claw pole 32, interlinks with the annular coil, and forms a closed magnetic path returning to the south pole on the back side of the magnet. In contrast, in a modification of the axial gap type rotating electric machine according to this embodiment, as shown in Fig. 7, the magnetization direction of the disk-shaped magnets 21a, 21a' is shifted by one pole in the circumferential direction from the axial direction so as to be oblique, and the claw poles 32 that face the front side of the disk-shaped magnets 21a, 21a' with a front-side N pole and a back-side S pole shifted by one pole in the circumferential direction on the front and back sides of the disk-shaped magnets 21a, 21a' are arranged to face the claw poles 32 that face the back side at the same position as the front side in Fig. 6 but shifted by one pole in the circumferential direction. With this configuration, as will be described later, the effective length of the magnet can be made longer than in the case of Fig. 6, thereby enabling significantly higher torque.

[0051] That is, in common with both the inner rotor type and the outer rotor type, the inner claw poles 32 and the outer claw poles 32' of the unit stator may not be arranged in the same positions on the front and back, but may be configured so that the upper claw poles 32, 32' face the north pole and the lower claw poles 32, 32' face the south pole on the back side, which is shifted by one pole in phase in the circumferential direction.The previously mentioned Figure 3 is configured in this way.

[0052] In this case, the effective magnetic thickness of the disk-shaped magnets 21, 21' that generate magnetomotive force is the number of pole pairs p and the actual magnetic thickness L of the disk-shaped magnets 21, 21'. m 7, the length L of the disk-shaped magnets 21a and 21a' is approximately three times that of the case in FIG. 6, and the magnetomotive force is proportional to this, so that a high-torque axial gap type rotating electric machine 10, 10' can be obtained. P is the effective magnet thickness of the present disk-shaped magnets 21a, 21a'.

[0053] From Ampere's circular law, the magnetic flux density in the air gaps of Figures 6 and 7 can be calculated as follows: Air gap magnetic flux density B in Figure 6 g1 =(μ0H m / 2L g )L m (1) Air gap magnetic flux density B in Figure 7 g2 =(μ0H m / 2L g )L P (2) where μ0 is the magnetic permeability of a vacuum, H m : Magnetic field strength of the magnet, L g : Air gap length, L P : The effective length of the magnet is as shown in Figure 7. From Figures 6 and 7, L P >L m Therefore, from (1) and (2) above, B g2 >B g1 In the case of FIG. 7, the torque is higher than that in FIG.

[0054] One of the inventors of this application presented a paper titled "Improving the Characteristics of PM-Type Stepping Motors" (Non-Patent Document 1) at the Motor Technology Symposium sponsored by the Japan Management Association in 1993, in which he proposed a "polar anisotropic magnet" with a U-shaped magnetic path. A conventional "polar anisotropic magnet" with a U-shaped magnetic path will be described later using an example of 12 poles in Figure 10, but the magnet configuration in Figure 7 can be said to be a new technology, a "new S-shaped magnetic path polar anisotropic magnet."

[0055] Figure 10 is a diagram of a 12-pole U-shaped magnetic path orientation, a polar anisotropy magnet of the prior art. Polar anisotropy is formed by applying a 12-pole magnetic field orientation during magnet molding, and was proposed by the present inventor in 1983. In this case, the magnetomotive force of the magnet after magnetization is proportional to L2 in Figure 10. In contrast, the magnetomotive force of a radially anisotropic magnet after magnetization is proportional to L1 in Figure 10. We can see that the former is about 2.5 times larger. In this case, it is the case of a radial gap magnet with single-sided magnetization, while Figure 7 of the present invention corresponds to the invention of a polar anisotropy orientation method when a magnet is used on both sides.

[0056] As described above, in the rotating electric machine according to this embodiment, the pair of claw pole members 20, 20 are not intermeshed but are arranged on both sides of the disk-shaped magnet 21, so no leakage magnetic flux is generated. Therefore, the tooth width of the claw pole 32 can be widened to the pole width of the disk-shaped magnet 21. As a result, the interlinkage magnetic flux is increased, and high torque is obtained.

[0057] Furthermore, the claw poles of the stator of the axial gap rotating electric machine according to this embodiment are manufactured from powdered iron cores rather than stamped out from electromagnetic steel plates as in conventional technology. Therefore, their shape offers a high degree of freedom. Furthermore, by tapering the claw poles radially from the base toward the tip on the non-air-gap side (not facing the rotor magnet), the amount of material used in the powdered iron core can be optimized and the weight can be reduced. For example, in Figure 3, the claw pole 32 has radially extending teeth, but the axial thickness on the non-air-gap side tapers gradually toward the tip. This is because the rotor magnetic flux concentrates near the base of the claw pole, increasing the magnetic flux density, whereas the magnetic flux density can be lower near the tooth tips, allowing for a thinner wall. Furthermore, by designing the claw poles so that the center of the tooth width on the air-gap side is thicker and the wall thickness is thinner circumferentially toward the tooth ends, the distribution waveform of the magnetic flux density in the air gap becomes closer to a sine wave, reducing harmonics and reducing vibration and noise during rotation.

[0058] Furthermore, in the above embodiment, the axial gap rotating electric machines 10, 10' have been described as being three-phase. However, the axial gap rotating electric machines 10, 10' according to this embodiment are not limited to being three-phase, and may be configured as two-phase rotating electric machines. In this case, two of the above-described unit stators may be arranged axially with a phase difference of 90° electrical angle. Alternatively, the stator may remain the same, but the magnetic pole positions of the two rotors may be shifted by 90°. It is clear from the claims that such modified or improved embodiments are also within the technical scope of the present invention. [Industrial Applicability]

[0059] The axial gap rotating electric machine of the present invention can be used as an electric motor or generator, and is extremely practical, being inexpensive, robust, lightweight, thin, short, and small, and suitable for high torque and high efficiency. For example, a one-phase rotating electric machine is ideal as a high-efficiency single-phase AC generator. A two-phase rotating electric machine is suitable for high-torque STM. A three-phase rotating electric machine, made with a powdered iron core, is suitable for a high-power BLDCM. Therefore, it is expected to make a great contribution to industry. [Explanation of symbols]

[0060] 10, 10′ Axial gap type rotating electric machine, 11 Stator, 11a, 11b, 11c Unit stators, 12 Rotor, 20, 20′ Claw pole members, 21, 21′ Disk-shaped magnets, 22, 22′ Ring coils, 23 Housing, 24 Shaft, 25, 36 Spacers, 26 Bearings, 27 Bracket, 28 Bobbin, 32, 32′ Claw poles, 35 Fixed shaft, 37 Cylindrical rotating body.

Claims

1. An axial gap type rotating electric machine having a stator and a rotor rotatably assembled to the stator with an air gap in the axial direction, the stator includes a pair of claw pole members each having a circular ring portion and p claw poles projecting radially from the circular ring portion in a radial direction, the claw pole members being arranged with a predetermined gap in the axial direction; and a unit stator in which an annular coil is arranged and sandwiched in the axial direction within the circular ring portion, the rotor is inserted into the gap and has a disk-shaped magnet whose front side is magnetized or magnetized with 2p poles, alternating north and south poles in the circumferential direction, and whose back side is magnetized or magnetized with 2p poles, alternating north and south poles in the circumferential direction, An axial gap type rotating electric machine characterized in that magnetic flux coming out from the front side of the disk-shaped magnet enters through the opposing claw pole, interlinks with the toroidal coil, and returns to the disk-shaped magnet via the opposing claw pole on the back side, forming a closed magnetic path. Here, p is an integer of 2 or more.

2. 2. The axial gap type rotating electric machine according to claim 1, The front and back of the disk-shaped magnet are magnetized with opposite polarities, The axial gap type rotating electric machine, wherein the claw poles of the pair of claw pole members are arranged in the same phase in the circumferential direction.

3. 2. The axial gap type rotating electric machine according to claim 1, The front and back of the disk-shaped magnet are magnetized to the same polarity, The axial gap type rotating electric machine is characterized in that the claw poles of the pair of claw pole members are arranged with a phase difference of a predetermined electrical angle in the circumferential direction.

4. 4. The axial gap type rotating electric machine according to claim 3, The disk-shaped magnet has a magnetic field orientation that extends diagonally from the axial direction across the front and back of the magnet, resulting in an equivalent effective magnet magnetization length that is longer than the thickness of the disk-shaped magnet.

5. 2. The axial gap type rotating electric machine according to claim 1, The axial gap type rotating electric machine is characterized in that a plurality of the stator units are stacked in the axial direction.

6. 6. The axial gap type rotating electric machine according to claim 5, an axial gap type rotating electric machine, characterized in that either the unit stators arranged in a stacked phase arrangement or the disk-shaped magnets facing the unit stators are arranged with a predetermined electrical angle shifted in the circumferential direction.

7. 2. The axial gap type rotating electric machine according to claim 1, An axial gap type rotating electric machine, characterized in that the annular coil is provided inside the disk-shaped magnet.

8. 2. The axial gap type rotating electric machine according to claim 1, The claw poles are configured such that the thickness of the claw poles on the side opposite the air gap that does not face the disk-shaped magnet tapers radially from the base to the tip.

9. 2. The axial gap type rotating electric machine according to claim 1, The claw poles are configured such that the central portion of the tooth width on the air gap side is thicker and the thickness is thinner circumferentially toward the tooth ends.

10. 2. The axial gap type rotating electric machine according to claim 1, The claw pole members are formed of powder iron cores.

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