Axial gap motor

Abstract

To provide an axial gap motor which enables downsizing and higher torque, and which allows easy adjustment of cogging torque.SOLUTION: An axial gap motor comprises an outer magnet group and an inner magnet group which have polarities in phases opposite to each other. The axial gap motor also has an intermediate magnet group arranged in a Halbach array between the outer magnet group and the inner magnet group. The outer magnet group is arranged on a rotor 1 concentrically with a radius R3. The inner magnet group is arranged on the rotor 1 concentrically with a radius R4 smaller than the radius R3. The intermediate magnet group is concentrically arranged at a position of a radius R5 that is a position between the outer magnet group and the inner magnet group on the rotor 1.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present invention relates to, for example, a small-sized, high-torque axial gap motor. [Background technology]

[0002] For example, as disclosed in Patent Document 1, an axial gap motor is known as a compact, high-output (high-torque) motor. An axial gap motor has a magnetic gap between a permanent magnet and a salient pole of a stator in a direction parallel to the rotation axis of the rotor. Unlike a typical radial gap motor, an axial gap motor generates a magnetic flux in the direction of the rotation axis. Furthermore, compared to a typical radial gap motor, an axial gap motor is thin and has excellent output density and efficiency. Furthermore, Patent Document 2 (paragraph 0008, etc.) discloses that a cogging torque is generated when a magnet rotates. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2022-178604 A [Patent Document 2] Patent No. 4095334 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the technology disclosed in Patent Document 1, in order to obtain a higher torque density, it is necessary to increase the magnetic flux density, but there is a limit to the miniaturization of the motor. It is also known that cogging torque (cogging) occurs in relation to the magnetic poles of the magnet and the salient poles of the iron core of the armature. Cogging is also disclosed in Patent Document 2. This cogging occurs due to the magnetic energy stored between the magnet and the iron core of the armature fluctuating with the rotation of the motor, and is the main cause of torque unevenness and rotation speed unevenness of a DC motor. For this reason, it is desirable to be able to freely design cogging (cogging torque) according to the characteristics required of the motor. However, in the technology disclosed in Patent Document 1, the degree of freedom in designing the cogging torque is low, making it difficult to adjust the cogging torque.

[0005] The present invention has been made in consideration of the technical problems described above, and has an object to provide an axial gap motor that can be made compact and have high torque, and in which the cogging torque can be easily adjusted. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the present invention provides an axial gap motor comprising an outer magnet group and an inner magnet group whose polarities are in opposite phase, and an intermediate magnet group arranged in a Halbach array between the outer magnet group and the inner magnet group. Effect of the Invention

[0007] According to the present invention, it is possible to provide an axial gap motor that can be made compact and have high torque, and in which the cogging torque can be easily adjusted. [Brief description of the drawings]

[0008] [Figure 1] 1 is an exploded perspective view showing an axial gap motor according to an embodiment of the present invention. [Diagram 2] FIG. 1 is a vertical cross-sectional view of an axial gap motor according to an embodiment. [Diagram 3] FIG. 2 is an explanatory diagram showing the arrangement and polarities of the outer permanent magnets, the inner permanent magnets, and the intermediate permanent magnets on the rotor. [Figure 4] FIG. 4 is an explanatory diagram showing the relationship of coils in a stator. [Diagram 5] FIG. 2 is a circuit diagram showing a control circuit and coil connections of an axial gap motor. [Figure 6] 1 is a diagram showing a current supply sequence of an axial gap motor. [Figure 7] 4 is an explanatory diagram showing the relationship between a radius R1 related to the arrangement of an outer salient pole portion in a stator and a radius R2 related to the arrangement of an inner salient pole portion. FIG. [Figure 8] 1 is an explanatory diagram showing the relationship between a radius R3 associated with the arrangement of outer permanent magnets in a rotor, a radius R4 associated with the arrangement of inner permanent magnets, and a radius R5 associated with the arrangement of intermediate permanent magnets. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] An axial gap motor 100 according to an embodiment will be described below with reference to the drawings. Fig. 1 to Fig. 4 show an axial gap motor 100 according to an embodiment of the present invention, and a rotor 1 and a stator 4 that constitute the axial gap motor 100. Fig. 1 is an exploded perspective view of the axial gap motor 100, and Fig. 2 is a vertical cross-sectional view showing the axial gap motor 100 in an assembled state. Fig. 3 is a plan view showing the rotor portion (the inner portion of the rotor 1), and Fig. 4 is a plan view showing the relationship between the stator 4 and the coils (outer coils 5-13, inner coils 14-22).

[0010] 1 and 2, rotor 1 has a flat disk portion 1a and a cylindrical portion 1b. Cylindrical portion 1b is inserted into the inner diameter portions of ball bearings 2 and 3, which will be described later, and is engaged with these ball bearings 2 and 3. Rotor 1 is configured to be rotatable relative to stator 4, which will be described later.

[0011] 2, in one ball bearing 2 (closer to rotor 1), its outer ring is engaged with a fixed cylinder 23 (described later), and its inner ring is engaged with the cylindrical portion 1b of the rotor 1. In the other ball bearing 3 (closer to stator 4), its outer ring is engaged with the stator 4 (described later), and its inner ring is engaged with the cylindrical portion 1b of the rotor 1.

[0012] Reference numeral 4 in Fig. 1 denotes a stator made of a soft magnetic material. The stator 4 has 18 salient poles 4a, 4b, 4c, 4d, 4e, 4f, 4g, 4h, 4i, 4j, 4k, 4l, 4m, 4n, 4p, 4q, 4r, and 4s on one of the disk surfaces. Of these, nine salient poles 4a, 4b, 4c, 4d, 4e, 4f, 4g, 4h, and 4i are concentrically arranged relatively outside (outer periphery) on the disk surface of the stator 4. The remaining nine salient poles 4j, 4k, 4l, 4m, 4n, 4p, 4q, 4r, and 4s are concentrically arranged relatively inside (center) on the disk surface of the stator 4.

[0013] Hereinafter, the nine outer salient pole portions (salient pole portions 4a, 4b, 4c, 4d, 4e, 4f, 4g, 4h, and 4i) may be referred to as "outer salient pole portions." Also, the nine inner salient pole portions (salient pole portions 4j, 4k, 4l, 4m, 4n, 4p, 4q, 4r, and 4s) may be referred to as "inner salient pole portions."

[0014] The outer salient pole portions 4a, 4b, 4c, 4d, 4e, 4f, 4g, 4h, 4i (4a to 4i) and the inner salient pole portions 4j, 4k, 4l, 4m, 4n, 4p, 4q, 4r, 4s are integrally provided on the stator 4 and protrude perpendicularly to the stator 4. The outer salient pole portions 4a to 4i and the inner salient pole portions 4j, 4k, 4l, 4m, 4n, 4p, 4q, 4r, 4s are formed in a shape such that a cross section (cross section when viewed in plan) when cut at a certain position in the axial direction is trapezoidal (may be arc-shaped).

[0015] The outer salient pole portions 4a to 4i are arranged at equal intervals (here, 40° intervals) from one another. The inner salient pole portions 4j, 4k, 4l, 4m, 4n, 4p, 4q, 4r, and 4s are also arranged at equal intervals (here, 40° intervals) from one another. In FIG. 1, the outer salient pole portions 4a to 4i are arranged in the order of the outer salient pole portions 4a, 4d, 4g, 4b, 4e, 4h, 4c, 4f, and 4i in a counterclockwise direction as viewed from the rotor 1 side. Similarly, the inner salient pole portions 4j, 4k, 4l, 4m, 4n, 4p, 4q, 4r, and 4s are arranged in the order of the inner salient pole portions 4j, 4m, 4q, 4k, 4n, 4r, 4l, 4p, and 4s in a counterclockwise direction as viewed from the rotor 1 side.

[0016] The outer salient pole portions 4a to 4i are located at a position of radius R1 on the surface of the stator 4 (positions on the concentric circle of radius R1 shown in FIG. 7), and are positions facing the outer magnet group (of the rotor 1) described below. The inner salient pole portions 4j, 4k, 4l, 4m, 4n, 4p, 4q, 4r, and 4s are located at a position of radius R2 on the surface of the stator 4 (positions on the concentric circle of radius R2 shown in FIG. 7), and are positions facing the inner magnet group (of the rotor 1) described below. The magnitude relationship between the radii R1 and R2 is R1>R2.

[0017] Moreover, the salient pole portion 4a of the outer salient pole portions 4a to 4i and the salient pole portion 4j of the inner salient pole portions 4j, 4k, 4l, 4m, 4n, 4p, 4q, 4r, and 4s are arranged at the same rotation angle position (at the same phase position). Similarly, the salient pole portion 4b and the salient pole portion 4k, the salient pole portion 4c and the salient pole portion 4l, the salient pole portion 4d and the salient pole portion 4m, the salient pole portion 4e and the salient pole portion 4n, the salient pole portion 4f and the salient pole portion 4p, the salient pole portion 4g and the salient pole portion 4q, the salient pole portion 4h and the salient pole portion 4r, and the salient pole portion 4i and the salient pole portion 4s are also formed at the same rotation angle position (at the same phase position).

[0018] 1 and 2, reference numeral 23 denotes a fixed cylinder that is secured (fixed) to the stator 4. The fixed cylinder 23 is inserted into a circular hole formed in the center of the stator 4. The fixed cylinder 23 is fitted to the outer ring of one of the ball bearings 2 (closer to the rotor 1) and holds the one of the ball bearings 2.

[0019] In this way, the rotor 1 is held by the fixed cylinder 23 via the ball bearing 2. The rotor 1 is also held by the stator 4 via the other ball bearing 3. The fixed cylinder 23 is fixed to the stator 4. With this configuration, the rotor 1 is attached concentrically to the stator 4 and can be displaced relative to the stator 4 in the rotational direction around the axis.

[0020] Reference numerals 5, 6, 7, 8, 9, 10, 11, 12, and 13 in Fig. 1 and Fig. 2 respectively denote outer coils. In Fig. 1 and Fig. 2, the nine outer coils 5 to 13 are arranged in the order of 5, 8, 11, 6, 9, 12, 7, 10, and 13 in a counterclockwise direction as viewed from the rotor 1 side. The outer coils 5 to 13 are wound around the corresponding outer salient pole portions 4a to 4i. Then, the end faces of the outer salient pole portions 4a to 4i are excited to a predetermined polarity (for example, N pole) according to the direction of current flow through the outer coils.

[0021] Of the outer coils 5 to 13, outer coils 5, 6, and 7 form a U-phase in a three-phase brushless motor. Furthermore, outer coils 8, 9, and 10 form a V-phase in the three-phase brushless motor, and outer coils 11, 12, and 13 form a W-phase in the three-phase brushless motor.

[0022] The outer coils 5, 6, and 7 are wound in the same direction to magnetize the outer salient poles 4a, 4b, and 4c with the same polarity. The outer coils 8, 9, and 10 are wound in the same direction to magnetize the outer salient poles 4d, 4e, and 4f with the same polarity. The outer coils 11, 12, and 13 are wound in the same direction to magnetize the outer salient poles 4g, 4h, and 4i with the same polarity.

[0023] Reference numerals 14, 15, 16, 17, 18, 19, 20, 21, and 22 in Fig. 1 and Fig. 2 indicate inner coils. In Fig. 1 and Fig. 2, the nine inner coils 14 to 22 are arranged in the order of the inner coils 14 to 22 in a counterclockwise direction as viewed from the rotor 1 side. The inner coils 14 to 22 are wound around the corresponding inner salient pole portions 4j, 4k, 4l, 4m, 4n, 4p, 4q, 4r, and 4s. Then, the end faces of the inner salient pole portions 4j, 4k, 4l, 4m, 4n, 4p, 4q, 4r, and 4s are excited to a predetermined polarity (for example, S pole) according to the direction of current flow through the inner coils.

[0024] Of the inner coils 14 to 22, inner coils 14, 15, and 16 form a U-phase in a three-phase brushless motor. Furthermore, inner coils 17, 18, and 19 form a V-phase in the three-phase brushless motor, and inner coils 20, 21, and 22 form a W-phase in the three-phase brushless motor.

[0025] The inner coils 14, 15, and 16 are wound in the same direction to always magnetize the inner salient poles 4j, 4k, and 4l with the same polarity. The inner coils 17, 18, and 19 are also wound in the same direction to always magnetize the inner salient poles 4m, 4n, and 4p with the same polarity. The inner coils 20, 21, and 22 are also wound in the same direction to always magnetize the inner salient poles 4q, 4r, and 4s with the same polarity.

[0026] The inner coils 14, 15, 16 are wound in the opposite direction to the outer coils 5, 6, 7, and always excite the end faces of the inner salient poles 4j, 4k, 4l with the opposite polarity to the outer salient poles 4d, 4e, 4f. The inner coils 14, 15, 16, together with the outer coils 5, 6, 7, constitute the U phase of the three-phase brushless motor.

[0027] The inner coils 17, 18, 19 are wound in the opposite direction to the outer coils 8, 9, 10, and always excite the end faces of the inner salient poles 4m, 4n, 4p with the opposite polarity to the outer salient poles 4d, 4e, 4f. The inner coils 17, 18, 19, together with the outer coils 8, 9, 10, constitute the V phase of the three-phase brushless motor.

[0028] The inner coils 20, 21, 22 are wound in the opposite direction to the outer coils 11, 12, 13, and always excite the end faces of the inner salient poles 4q, 4r, 4s with the polarity opposite to that of the outer salient poles 4g, 4h, 4i. The inner coils 20, 21, 22, together with the outer coils 11, 12, 13, constitute the W phase of the three-phase brushless motor. In this manner, in the stator 4, the outer coils 5-13 are wound around the outer salient poles 4a-4i to form nine (nine locations) outer electromagnets, and the inner coils 14-22 are wound around the inner salient poles 4j, 4k, 4l, 4m, 4n, 4p, 4q, 4r, 4s to form nine (nine locations) inner electromagnets.

[0029] Fig. 3 is a plan view of the rotor 1 as viewed from the stator 4 side. Fig. 3 shows the relationship between the outer magnet group, inner magnet group, and intermediate magnet group provided on the rotor 1. Reference numerals 24a, 24b, 24c, 24d, 24e, 24f, 24g, 24h, 24i, 24j, 24k, and 24l in Fig. 3 indicate 12 outer permanent magnets. The outer permanent magnets 24a to 24l form the outer magnet group.

[0030] The outer permanent magnets 24a-24l are arranged at equal intervals (here, at intervals of 30 degrees) from one another on the flat disk portion 1a of the rotor 1. The outer permanent magnets 24a-24l are positioned on a concentric circle of radius R3 on the disk surface of the stator 4, as shown in Fig. 8, and face the end faces of the outer salient pole portions 4a-4i of the stator 4 with a predetermined interval therebetween.

[0031] The magnetization direction of the outer permanent magnets 24a to 24l is parallel to the rotation axis of the rotor 1. In addition, every other one of the six outer permanent magnets 24a, 24c, 24e, 24g, 24i, and 24k is magnetized so that the surface facing the end face of the outer salient pole portion 4a to 4i of the stator 4 becomes an N pole. The opposite surface of each of the six outer permanent magnets 24a, 24c, 24e, 24g, 24i, and 24k becomes an S pole.

[0032] The other six outer permanent magnets 24b, 24d, 24f, 24h, 24j, and 24l (permanent magnets arranged between the six outer permanent magnets 24a, 24c, 24e, 24g, 24i, and 24k) are magnetized so that the surfaces facing the end faces of the outer salient pole portions 4a to 4i of the stator 4 become S poles. The opposite surfaces of the six outer permanent magnets 24b, 24d, 24f, 24h, 24j, and 24l become N poles.

[0033] Reference numerals 25a, 25b, 25c, 25d, 25e, 25f, 25g, 25h, 25i, 25j, 25k, and 25l in Fig. 3 indicate 12 inner permanent magnets. The inner permanent magnets 25a to 25l form an inner magnet group. The inner permanent magnets 25a to 25l are arranged at equal intervals (here, at intervals of 30 degrees) on the flat disk portion 1a of the rotor 1. The inner permanent magnets 25a to 25l are positioned on a concentric circle of radius R4 on the disk surface of the stator 4 as shown in Fig. 8, and face the end faces of the inner salient pole portions 4j, 4k, 4l, 4m, 4n, 4p, 4q, 4r, and 4s of the stator 4 with a predetermined interval therebetween.

[0034] The magnetization direction of the inner permanent magnets 25a to 25l is parallel to the rotation axis of the rotor 1. In addition, every other one of the six inner permanent magnets 25a, 25c, 25e, 25g, 25i, and 25k is magnetized so that the surface facing the end faces of the inner salient pole portions 4j, 4k, 4l, 4m, 4n, 4p, 4q, 4r, and 4s of the stator 4 becomes an S pole. The opposite surfaces of the six inner permanent magnets 25a, 25c, 25e, 25g, 25i, and 25k become an N pole.

[0035] The other six inner permanent magnets 25b, 25d, 25f, 25h, 25j, and 25l (permanent magnets arranged between the six inner permanent magnets 25a, 25c, 25e, 25g, 25i, and 25k) are magnetized so that the surfaces facing the end faces of the inner salient poles 4j, 4k, 4l, 4m, 4n, 4p, 4q, 4r, and 4s of the stator 4 are N poles. The opposite surfaces of the six inner permanent magnets 25b, 25d, 25f, 25h, 25j, and 25l are S poles.

[0036] Among the inner permanent magnets 25a to 25l, the inner permanent magnet 25a is attached inside at the same rotation angle position (same phase position) as the outer permanent magnet 24a. Similarly, the inner permanent magnets 25b to 25l are attached inside at the same rotation angle position (same phase position) as the outer permanent magnets 24b to 24l, respectively. In addition, the polarity of the six inner permanent magnets 25a, 25c, 25e, 25g, 25i, and 25k arranged every other one is opposite to the polarity of the outer permanent magnets 24a, 24c, 24e, 24g, 24, and 24k arranged on the outside at the same angular position (same phase). The polarity of the other six inner permanent magnets 25b, 25d, 25f, 25h, 25j, and 25l is opposite to the polarity of the outer permanent magnets 24b, 24d, 24f, 24h, 24j, and 24l arranged on the outside at the same angular position (same phase).

[0037] Reference numerals 26a, 26b, 26c, 26d, 26e, 26f, 26g, 26h, 26i, 26j, 26k, and 26l in Fig. 3 indicate 12 intermediate permanent magnets. The intermediate permanent magnets 26a to 26l form an intermediate magnet group. The intermediate permanent magnets 26a to 26l are arranged at equal intervals (here, intervals of 30 degrees) on the flat disk portion 1a of the rotor 1. The intermediate permanent magnets 26a to 26l are arranged at positions between the outer permanent magnets 24a to 24l and the inner permanent magnets 25a to 25l (positions on the concentric circle of R5 where R3>R5>R4 in Fig. 8).

[0038] The six intermediate permanent magnets 26a, 26c, 26e, 26g, 26i, 26k arranged every other one are magnetized in a direction facing the outer permanent magnets 24a, 24c, 24e, 24g, 24i, 24k and the inner permanent magnets 25a, 25c, 25e, 25g, 25i, 25k. The surfaces of the intermediate permanent magnets 26a, 26c, 26e, 26g, 26i, 26k facing the outer permanent magnets 24a, 24c, 24e, 24g, 24i, 24k are magnetized so as to have the same polarity (i.e., N pole) as the surfaces of the outer permanent magnets 24a, 24c, 24e, 24g, 24i, 24k facing the end faces of the outer salient pole portions of the stator 4. The surfaces of the intermediate permanent magnets 26a, 26c, 26e, 26g, 26i, and 26k facing the inner permanent magnets 25a, 25c, 25e, 25g, 25i, and 25k are magnetized so as to have the same polarity (i.e., the S pole) as the surfaces of the inner permanent magnets 25a, 25c, 25e, 25g, 25i, and 25k facing the end faces of the inner salient pole portion of the stator 4.

[0039] The other six intermediate permanent magnets 26b, 26d, 26f, 26h, 26j, 26l are magnetized in a direction facing the outer permanent magnets 24b, 24d, 24f, 24h, 24j, 24l and the inner permanent magnets 25b, 25d, 25f, 25h, 25j, 25l. The surfaces of the intermediate permanent magnets 26b, 26d, 26f, 26h, 26j, 26l facing the outer permanent magnets 24b, 24d, 24f, 24h, 24j, 24l are magnetized so as to have the same polarity (i.e., S pole) as the surfaces of the outer permanent magnets 24b, 24d, 24f, 24h, 24j, 24l facing the end faces of the outer salient pole portions of the stator 4. The surfaces of the intermediate permanent magnets 26b, 26d, 26f, 26h, 26j, and 26l facing the inner permanent magnets 25b, 25d, 25f, 25h, 25j, and 25l are magnetized so as to have the same polarity (i.e., the N pole) as the surfaces of the inner permanent magnets 25b, 25d, 25f, 25h, 25j, and 25l facing the end faces of the inner salient pole portion of the stator 4.

[0040] As described above, the intermediate permanent magnets 26a-26l are arranged concentrically with a radius R5 between the outer permanent magnets 24a-24l of the outer magnet group and the inner permanent magnets 25a-25l of the inner magnet group. The intermediate permanent magnets 26a-26l are magnetized so that the magnetization direction faces the outer permanent magnets 24a-24l and the inner permanent magnets 25a-25l, respectively. Furthermore, the intermediate permanent magnets 26a-26l are arranged so that the polarity of the surface facing the outer permanent magnets 24a-24l is the same as the polarity of the surface of the outer permanent magnets 24a-24l facing the outer salient pole portions 4a-4i of the stator 4. Moreover, the intermediate permanent magnets 26a to 26l are arranged such that the polarity of the surface facing the inner permanent magnets 25a to 25l is the same as the polarity of the surface facing the inner salient pole portions 4j, 4k, 4l, 4m, 4n, 4p, 4q, 4r, and 4s of the stator 4. In this manner, the intermediate permanent magnets 26a to 26l form an intermediate magnet group.

[0041] By arranging the various permanent magnets in this way, the outer magnet group, the inner magnet group, and the intermediate magnet group form a radial Halbach field magnet. As a result, it is possible to extract as much magnetic flux density as possible from the surfaces of the outer magnet group and the inner magnet group that face the salient pole portions (outer salient pole portions 4a to 4i, inner salient pole portions 4j, 4k, 4l, 4m, 4n, 4p, 4q, 4r, 4s) of the stator 4.

[0042] In the axial gap motor 100 of this embodiment, by providing an outer magnet group and an inner magnet group, the permanent magnet is divided, unlike the conventional one in which a single permanent magnet is used for each rotation angle range (each specified phase). Then, for each divided magnet, the ratio of the magnetic pole area to the magnetic pole distance (magnetic pole distance / magnetic pole area) becomes large, and the permeance coefficient Pc, which will be described later, also becomes large. In this way, the permeance coefficient Pc can be increased, making it possible to extract a large magnetic flux density.

[0043] Furthermore, by interposing the intermediate magnet group between the outer magnet group and the inner magnet group, a Halbach field can be formed between these permanent magnets (between the intermediate permanent magnets 26a-26l and the outer permanent magnets 24a-24l and the inner permanent magnets 25a-25l). As a result, it is possible to obtain even greater magnetic flux density.

[0044] As a result, the axial gap motor 100 of this embodiment is able to generate even greater torque.

[0045] Fig. 5 shows the control circuit 110 and coil connections in a magnet type three-phase brushless motor. Tr1, Tr2, Tr3, Tr4, Tr5, and Tr6 in Fig. 5 are transistors in the magnet type three-phase brushless motor drive circuit (control circuit 110). Fig. 6 is a coil excitation table showing the excitation state of the coils according to the current supply sequence.

[0046] As shown in Fig. 5, the outer coils 5-7 and the inner coils 14-16 are connected in parallel. The outer coils 5-7 and the inner coils 14-16 form the U-phase of a three-phase brushless motor. Depending on the winding direction and connection state of the outer coils 5-7 and the inner coils 14-16, the outer salient poles 4a-4c excited by the outer coils 5-7 and the inner salient poles 4j-4l excited by the inner coils 14-16 are excited with opposite polarities when current is applied.

[0047] With regard to the outer coils 5-7 and the inner coils 14-16, as long as the outer salient pole portions 4a-4c and the inner salient pole portions 4j-4l are excited with opposite polarities, some or all of the outer coils 5-7 and the inner coils 14-16 may be connected in series.

[0048] As shown in Fig. 5, the outer coils 8-10 and the inner coils 17-19 are connected in parallel. The outer coils 8-10 and the inner coils 17-19 form the V phase of a three-phase brushless motor. Depending on the winding direction and connection state of the outer coils 8-10 and the inner coils 17-19, the outer salient poles 4d-4f excited by the outer coils 8-10 and the inner salient poles 4m, 4n, and 4p excited by the inner coils 17-19 are excited with opposite polarities when electricity is applied.

[0049] With regard to the outer coils 8-10 and the inner coils 17-19, as long as the excited outer salient pole portions 4d-4f and the inner salient pole portions 4m, 4n, 4p are excited with opposite polarities, some or all of the outer coils 8-10 and the inner coils 17-19 may be connected in series.

[0050] As shown in Fig. 5, the outer coils 11-13 and the inner coils 20-22 are connected in parallel. The outer coils 11-13 and the inner coils 20-22 form the W-phase of a three-phase brushless motor. Depending on the winding directions and connection states of the outer coils 11-13 and the inner coils 20-22, the outer salient poles 4g-4i excited by the outer coils 11-13 and the inner salient poles 4q-4s excited by the inner coils 20-22 are excited with opposite polarities when current is applied.

[0051] With regard to the outer coils 11-13 and the inner coils 20-22, as long as the excited outer salient pole portions 4g-4i and the inner salient pole portions 4q-4s are excited with opposite polarities, some or all of the outer coils 11-13 and the inner coils 20-22 may be connected in series.

[0052] Figure 6 is a coil excitation table showing the energization sequence. As shown from the left in the top row of Figure 6, the coil excitation state changes sequentially from state 1 to state 6 by switching the energization, and rotation similar to that of a magnet rotor type three-phase brushless motor occurs.

[0053] For example, Tr1 is ON in the third and fourth states, Tr2 is ON in the first and second states and in the fifth and sixth states, Tr3 is ON in the fifth and sixth states, Tr4 is ON in the first and sixth states, Tr5 is ON in the fourth and fifth states, and Tr6 is ON in the second and third states.

[0054] The polarity of the outer coils 5-7 constituting the U phase is S pole in the first state and N pole in the third and fourth states. Furthermore, the polarity of the outer coils 5-7 is S pole in the sixth state. The polarity of the inner coils 14-16 constituting the U phase is N pole in the first state and S pole in the third and fourth states. Furthermore, the polarity of the inner coils 14-16 is N pole in the sixth state.

[0055] The polarity of the outer coils 8-10 constituting the V phase is N pole in the first and second states, and S pole in the fourth and fifth states. Furthermore, the polarity of the inner coils 17-19 constituting the V phase is S pole in the first and second states, and N pole in the fourth and fifth states.

[0056] The polarity of the outer coils 11-13 constituting the W phase is S pole in the second and third states, and N pole in the fifth and sixth states. Furthermore, the polarity of the inner coils 20-22 constituting the W phase is N pole in the second and third states, and S pole in the fifth and sixth states.

[0057] The axial gap motor 100 described above includes an outer magnet group (outer permanent magnets 24a to 24l) and an inner magnet group (inner permanent magnets 25a to 25l) whose polarities are in opposite phases, and an intermediate magnet group (intermediate permanent magnets 26a to 26l) is disposed between the outer magnet group and the inner magnet group. In other words, the structure of the axial gap motor is such that the intermediate magnet group and the inner magnet group are sequentially disposed inside the outer magnet group, forming a Halbach array and a Halbach field magnet in the radial direction.

[0058] Therefore, a Halbach array and a Halbach field magnet can be configured without enlarging (enlarging) the rotor 1 (and the stator 4) and each permanent magnet (the outer permanent magnets 24a to 24l, the inner permanent magnets 25a to 25l, and the intermediate permanent magnets 26a to 26l) in the circumferential direction (and radial direction) as shown by the symbol L in FIG. 8, making it possible to provide a small-sized, high-torque axial gap motor.

[0059] Specifically, if one wishes to increase the magnetic flux density by using a Halbach array in the circumferential direction, it is necessary to increase the diameters of the rotor 1 and the stator 4 so that the circumference of the axial gap motor becomes larger.

[0060] For example, the conventional axial gap motor disclosed in the above-mentioned Patent Document 1 has main permanent magnets arranged alternately at the same radial position on a disk (on a stator) with magnets of different poles magnetized in a direction parallel to the rotating shaft. The axial gap motor disclosed in Patent Document 1 generates rotational force by a stator having a magnetic gap in a direction parallel to the rotating shaft. The axial gap motor disclosed in Patent Document 1 also configures a Halbach field by arranging auxiliary permanent magnets magnetized in a direction between main permanent magnets of different poles magnetized in a direction parallel to the rotating shaft, and thereby increasing the magnetic flux density generated from the main permanent magnets and increasing the torque.

[0061] In the conventional axial gap motor disclosed in Patent Document 1, if a further increase in torque is required, it is necessary to further increase the magnetic flux density, but there is a limit to how much the magnetic flux density can be increased by the magnet material. Furthermore, simply increasing the area of ​​the permanent magnet reduces the permeance coefficient and lowers the magnetic flux density, so there is a limit to how much torque can be increased.

[0062] For example, the permeance coefficient Pc of a permanent magnet in a cylindrical shape of radius r and length L that is magnetized parallel to the cylindrical axis is approximated by the following formula. Pc=a×(L / 2r)×(√(1+(L / 2r)×(L / 2r))+L / 2r) where a is a correction factor. From this formula, if the permanent magnet area is increased with the same polarity, the permeance coefficient decreases and the magnetic flux density decreases. Therefore, for example, in the invention disclosed in the above-mentioned Patent Document 1, it is difficult to increase the motor torque even if the permanent magnet area is increased. Basically, when the magnetic flux density is increased, a motor with high torque at low speed is obtained, and when the magnetic flux density is decreased, a motor with low torque at high speed is obtained.

[0063] In response to these circumstances, by configuring a Halbach array and Halbach field magnet in the radial direction, as in the axial gap motor of this embodiment, it is possible to increase the magnetic flux density without expanding in the radial direction (and circumferential direction), thereby making it possible to provide a small-sized, high-torque axial gap motor.

[0064] In addition, since the Halbach array and Halbach field magnet are formed in the radial direction, for example, if the size in the radial direction (and circumferential direction) is made the same as that of the conventional one (such as the invention disclosed in the above-mentioned Patent Document 1), the Halbach array and Halbach field magnet can be formed by arranging and storing the intermediate magnet group and the inner magnet group in the space available in the radial direction. Therefore, it is possible to provide a small-sized, high-torque axial gap motor without expanding in the radial direction (and circumferential direction).

[0065] Moreover, with the axial gap motor according to this embodiment, it is possible to achieve high torque without changing the size or position of the outer permanent magnets 24a-24l that constitute the outer magnet group. Also, it is possible to achieve high torque by using the inner permanent magnets 25a-25l that constitute the inner magnet group.

[0066] Furthermore, for example, when a Halbach array is configured in the circumferential direction as in the invention disclosed in Patent Document 1 mentioned above, the magnet arrangement in the circumferential direction (rotation direction) is changed compared to an axial gap motor of a type that does not have a Halbach array, and the cogging (cogging torque) characteristics (cogging characteristics) are likely to change.

[0067] For example, as disclosed in the above-mentioned Patent Document 2 (paragraphs 0049 to 0055, FIG. 14, etc.), the ratio of the circumferential magnet area to the opposing yoke area has a significant effect on the cogging characteristics. When a circumferential Halbach array is adopted, there are significant restrictions on the ratio of the circumferential dimensions, making it difficult to design the cogging characteristics to the desired characteristics. In some cases, the cogging becomes excessively large, impairing the performance of the motor.

[0068] In contrast, according to the axial gap motor 100 of this embodiment, the Halbach array can be configured without changing the circumferential dimension. Therefore, when increasing the torque of the axial gap motor 100, there is no need to change the size or position of the outer permanent magnets 24a to 24l that constitute the outer magnet group. In addition, the inner permanent magnets 25a to 25l that constitute the inner magnet group also increase the torque. Furthermore, the intermediate magnet group and the inner magnet group are arranged inside the outer magnet group in the same phase as the outer magnet group (in a state where the phase of arrangement is the same and the rotation angle range is the same). Therefore, the cogging characteristics can be set (adjusted) based on the arrangement of the outer magnet group. Then, the magnetic flux density of the magnets can be increased while obtaining the desired cogging characteristics, and high torque is possible. Furthermore, it is possible to provide an axial gap motor 100 in which the cogging characteristics can be easily set and adjusted, and the degree of freedom in designing cogging is high.

[0069] Here, the cogging characteristics required vary depending on the electric device (product) in which the axial gap motor 100 is incorporated. For example, in products that do not tolerate torque pulsation, it is said that a smaller cogging torque is better. Also, when emphasis is placed on the stopping ability of the motor (characteristics such as ease of stopping), the cogging torque is increased. Also, in order to facilitate current control of the motor, a smaller cogging torque is better. Furthermore, when precise control of the rotational position of the motor is desired, a smaller cogging torque is better. For example, when performing an enticing action such as jigging operation in fishing, it is considered to be advantageous to ensure a certain degree of cogging torque in an electric reel with a built-in motor. Therefore, when considering using the axial gap motor 100 of this embodiment in various products, the cogging characteristics can be easily adjusted, making it easy to accommodate various products.

[0070] Furthermore, according to the axial gap motor 100 of this embodiment, the outer magnet group is concentrically arranged on the rotor 1 with a first radius (R3), the inner magnet group is concentrically arranged on the rotor 1 with a second radius (R4) smaller than the first radius (R3), and the intermediate magnet group is concentrically arranged at a position (position of third radius R3) between the outer magnet group and the inner magnet group on the rotor 1. Therefore, a Halbach field magnet can be appropriately configured by the outer magnet group, the inner magnet group, and the intermediate magnet group.

[0071] Furthermore, according to the axial gap motor 100 of this embodiment, the outer magnet group is composed of a plurality of outer permanent magnets 24a-24l, the inner magnet group is composed of a plurality of inner permanent magnets 25a-25l, and the intermediate magnet group is composed of a plurality of intermediate permanent magnets 26a-26l, and a plurality of sets of the outer permanent magnets 24a-24l, the inner permanent magnets 25a-25l, and the intermediate permanent magnets 26a-26l that constitute the Halbach array are radially arranged. Therefore, the outer permanent magnets 24a-24l, the inner permanent magnets 25a-25l, and the intermediate permanent magnets 26a-26l can appropriately form a Halbach field magnet.

[0072] Furthermore, according to the axial gap motor 100 of this embodiment, the rotor 1 is rotated by changing the excitation states of the outer coils 5 to 13 and the inner coils 14 to 22. Therefore, the rotor 1 can be appropriately rotated by the Halbach array outer magnet group, inner magnet group, and intermediate magnet group.

[0073] In this embodiment, a three-phase brushless motor is used as the axial gap motor, but the present invention is not limited to this. For example, a four-phase or five-phase configuration may be used.

[0074] Furthermore, the axial gap motor according to this embodiment can be used in a variety of electrical devices that use an axial gap motor. Some examples of electrical devices to which an axial gap motor can be applied include fishing reels with motors built in, electric winches, and electric vehicles (drive wheels).

[0075] The following inventions can be extracted from the above-described embodiment. (1) An axial gap motor comprising an outer magnet group and an inner magnet group whose polarities are in opposite phase, and an intermediate magnet group arranged in a Halbach array between the outer magnet group and the inner magnet group. (2) the outer magnet group is arranged concentrically on a rotor (e.g., Rotor 1) at a first radius (e.g., radius R3); the inner magnet group is concentrically arranged on the rotor at a second radius (e.g., R4) that is smaller than the first radius; The axial gap motor described in (1) above, wherein the intermediate magnet group is concentrically arranged on the rotor at a position between the outer magnet group and the inner magnet group (position R5 as the third radius). (3) The outer magnet group is composed of a plurality of outer permanent magnets (outer permanent magnets 24a to 24l, etc.), The inner magnet group is composed of a plurality of inner permanent magnets (inner permanent magnets 25a to 25l, etc.), The intermediate magnet group is composed of a plurality of intermediate permanent magnets (intermediate permanent magnets 26a to 26l, etc.), The axial gap motor according to (2) above, wherein a plurality of sets of the outer permanent magnet, the inner permanent magnet, and the intermediate permanent magnet that constitute the Halbach array are arranged radially. (4) An axial gap motor according to any one of (2) or (3) above, in which coils (outer coils 5 to 13, inner coils 14 to 22, etc.) are wound around each of a plurality of salient poles (outer salient poles 4a to 4i, inner salient poles 4j, 4k, 4l, 4m, 4n, 4p, 4q, 4r, 4s, etc.) formed on a stator (such as stator 4) facing the rotor, and the rotor is rotated by changing the excitation state of the coils.

[0076] Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and can be practiced in various modifications without departing from the gist of the present invention.

[0077] For example, although not shown, each of the intermediate permanent magnets 26a-26l may be divided into a plurality of pieces (for example, two pieces) in the circumferential direction (the direction of the symbol L in FIG. 8), and the plurality of intermediate permanent magnets 26a-26l may be arranged for a set of one outer permanent magnet 24a-24l and one inner permanent magnet 25a-25l. In this way, when the magnetic flux density is increased, the axial gap motor 100 can be made smaller and thinner. [Industrial Applicability]

[0078] The present invention can be used in industrial fields related to axial gap motors and in various electrical equipment fields that incorporate axial gap motors. [Explanation of symbols]

[0079] 1: Rotor 4: Stator 4a~4i: Outer salient pole part 4j, 4k, 4l, 4m, 4n, 4p, 4q, 4r, 4s: Inner protrusion 5~13: Outer coil 14~22: Inner coil 24a~24l: Outside permanent magnet 25a~25l: Inner permanent magnet 26a~26l: Intermediate permanent magnet 100: Axial gap motor 110: Control circuit

Claims

1. An axial gap motor comprising an outer magnet group and an inner magnet group whose polarities are in opposite phase, and an intermediate magnet group arranged in a Halbach array between the outer magnet group and the inner magnet group.

2. the outer magnet group is arranged on the rotor in a concentric circle of a first radius; the inner magnet group is concentrically arranged on the rotor at a second radius smaller than the first radius; The axial gap motor according to claim 1 , wherein the intermediate magnet group is concentrically arranged on the rotor at a position between the outer magnet group and the inner magnet group.

3. The outer magnet group is composed of a plurality of outer permanent magnets, The inner magnet group is composed of a plurality of inner permanent magnets, The intermediate magnet group is composed of a plurality of intermediate permanent magnets, The axial gap motor according to claim 2 , wherein a plurality of sets of the outer permanent magnet, the inner permanent magnet, and the intermediate permanent magnet that constitute the Halbach array are arranged radially.

4. 4. The axial gap motor according to claim 2, wherein a coil is wound around each of a plurality of salient poles formed on a stator facing the rotor, and the rotor is rotated by changing the excitation state of the coils.

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