Axial gap type rotating electric machine

Abstract

To provide an axial gap type rotating electric machine that allows for setting the air gap with a simple configuration and can be manufactured inexpensively by suppressing manufacturing costs. [Solution] An axial gap type rotating electric machine having a stator and a rotor rotatably mounted to the stator with an air gap in the axial direction, wherein the stator comprises a stator body and a plurality of coil members wound around the stator body, and the stator body comprises an annular portion, a plurality of protrusions projecting axially from the annular portion and to which the coil members are mounted, and an air gap setting means.

Description

Technical Field

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

Background Art

[0002] Rotating electrical machines are strongly required to be smaller, thinner, more efficient, less vibratory, less noisy, and less expensive in addition to the requirements of the market. Among them, an axial-gap rotating electrical machine having an air gap in the direction of the rotating shaft (hereinafter, also referred to as the "axial direction") is a form that has attracted attention in recent years because it is an advantageous structure for forming a flat and thin shape.

[0003] Such axial-gap rotating electrical machines are known in various forms. For example, the form described in Patent Document 1 is known. For example, the axial-gap rotating electrical machine described in Patent Document 1 is provided with a stator and a rotor rotatable with respect to the stator, and the stator and the rotor are opposed to each other with a gap therebetween along the rotation axis of the rotor. At least one of the stator and the rotor includes a coil and a core member around which the coil is wound, and the core member is formed of a soft magnetic material.

[0004] According to the axial-gap rotating electrical machine described in Patent Document 1, the axial-gap rotating electrical machine can be configured at a lower cost.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, the axial gap type rotating electric machine described in Patent Document 1 does not have a structure for setting the axial air gap between the stator and the rotor, and it is necessary to set the air gap separately, which means that it is not necessarily possible to construct an axial gap type rotating electric machine at a low cost. In addition, since the core member is manufactured by machining a soft magnetic material, it is not necessarily possible to suppress manufacturing costs.

[0007] Furthermore, for example, when using a rotating electric machine as a joint in a robot arm, it needs to be installed inside the robot arm or between adjacent robot arms. In the invention described in Patent Document 1, the joint portion is unitized. However, there is a need from robot arm manufacturers to incorporate a rotating electric machine into the robot arm, and in that case, since the frame of the rotating electric machine and the frame of the robot arm must be prepared separately, the frame becomes double, which leads to the problem of increasing the size and weight of the robot arm.

[0008] Furthermore, properly setting the axial air gap between the stator and rotor significantly affects the output characteristics and efficiency of a rotating electric machine. If the air gap cannot be set appropriately, variations in output characteristics and efficiency will occur, making it impossible to provide a high-performance axial-gap rotating electric machine. In addition, because the stator and rotor of an axial-gap rotating electric machine are arranged with an air gap in the axial direction, the stator and rotor are subjected to forces that cause them to move closer together or further apart in the axial direction due to the influence of the magnetic force generated between them, which makes it difficult to properly set the axial air gap.

[0009] 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 set the air gap with a simpler configuration compared to conventional axial gap type rotating electric machines, and can be manufactured at a low cost by suppressing manufacturing costs. [Means for solving the problem]

[0010] The present invention, which solves the above problems, is 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 comprises a stator body and a plurality of coil members wound around the stator body, and the stator body has an annular portion, a plurality of protrusions projecting axially from the annular portion and to which the coil members are assembled, and an air gap setting means.

[0011] Furthermore, in the axial gap type rotating electric machine according to the present invention, the rotor preferably comprises a disc-shaped rotor body and a plurality of permanent magnets arranged circumferentially on the surface of the rotor body facing the stator.

[0012] Furthermore, in the axial gap type rotating electric machine according to the present invention, it is preferable that the stator body is formed from a powdered iron core.

[0013] Furthermore, in the axial gap type rotating electric machine according to the present invention, the air gap setting means comprises either a bearing or a shaft member fitted to the stator body and the other either a bearing or a shaft member fitted to the rotor, wherein the shaft member is preferably assembled to either the inner ring or the outer ring of the bearing.

[0014] The above summary of the invention does not enumerate all the necessary features of the present invention, and subcombinations of these features may also constitute the invention. [Effects of the Invention]

[0015] According to the axial gap type rotating electric machine of the present invention, since the stator is equipped with an air gap setting means, the air gap in the rotational axis direction (axial direction) between the stator and the rotor can be appropriately adjusted with a simple configuration, and an axial gap type rotating electric machine that can obtain the desired output can be provided.

[0016] In addition, since the stator body is formed of a powder compacted iron core, a plurality of protrusions formed on the stator body can be easily formed by die molding, and an axial gap type rotating electric machine can be provided at a low cost by suppressing the manufacturing cost.

Brief Description of the Drawings

[0017] [Figure 1] Perspective view showing an axial gap type rotating electric machine according to an embodiment of the present invention. [Figure 2] Exploded view of an axial gap type rotating electric machine according to an embodiment of the present invention. [Figure 3] Cross-sectional view taken along line A-A in FIG. 1. [Figure 4] Perspective view showing a stator used in an axial gap type rotating electric machine according to an embodiment of the present invention. [Figure 5] Perspective view showing a rotor used in an axial gap type rotating electric machine according to an embodiment of the present invention. [Figure 6] Perspective view showing an air gap setting means used in an axial gap type rotating electric machine according to the present embodiment of the present invention. [Figure 7] Perspective view showing a shaft member used in an axial gap type rotating electric machine according to an embodiment of the present invention.

Embodiments for Carrying Out the Invention

[0018] Hereinafter, preferred embodiments for carrying out the present invention will be described with reference to the drawings. Note that the following embodiments do not limit the invention according to each claim, and not all combinations of features described in the embodiments are essential for the solution means of the invention.

[0019] FIG. 1 is a perspective view showing an axial-gap type rotating electric machine according to an embodiment of the present invention, FIG. 2 is an exploded view of the axial-gap type rotating electric machine according to the embodiment of the present invention, FIG. 3 is a cross-sectional view taken along line A-A in FIG. 1, FIG. 4 is a perspective view showing a stator used in the axial-gap type rotating electric machine according to the embodiment of the present invention, FIG. 5 is a perspective view showing a rotor used in the axial-gap type rotating electric machine according to the embodiment of the present invention, FIG. 6 is a perspective view showing air-gap setting means used in the axial-gap type rotating electric machine according to the present embodiment of the present invention, and FIG. 7 is a perspective view showing a shaft member used in the axial-gap type rotating electric machine according to the embodiment of the present invention.

[0020] As shown in FIGS. 1 to 3, the axial-gap type rotating electric machine 10 according to the present embodiment includes a disk-shaped stator 20 and a disk-shaped rotor 30 that is rotatably assembled with an air gap G in the axial direction of the stator 20.

[0021] Further, the stator 20 and the rotor 30 are assembled via air-gap setting means 40, and the air-gap setting means 40 enables adjustment of the axial air gap G between the stator 20 and the rotor 30 to an appropriate interval.

[0022] As shown in FIG. 4, the stator 20 includes a stator body 21 having a disk-shaped annular portion, and a plurality of protrusions 22 having a fan-shaped cross-sectional shape perpendicular to the axis and protruding axially from the surface of the stator body 21 are formed at predetermined intervals in the circumferential direction. A coil member 23 is wound around each of the protrusions 22. In the axial-gap type rotating electric machine 10 according to the present embodiment, twelve protrusions 22 are formed along the circumferential direction on the stator body 21.

[0023] The stator body 21 is formed of a compressed powder core, and the plurality of protrusions 22 described above are formed integrally with the stator body 21. Further, a bearing mounting hole 24 into which a bearing 42 described later is press-fitted is formed in the central portion of the stator body 21.

[0024] The coil member 23 is constructed by winding a winding around the axis of the protrusion 22, and concentrated winding, distributed winding, etc. can be selected as appropriate.

[0025] As shown in Figure 5, the rotor 30 comprises a disc-shaped rotor body 31 and a plurality of permanent magnets 32 arranged circumferentially on the surface of the rotor body 31.

[0026] It is preferable that the permanent magnets 32 have their front side arranged in a circumferential direction with alternating N-pole and S-pole configurations, forming 2p poles. In this embodiment, the case in which 16 permanent magnets 32 are arranged in the circumferential direction in the axial gap type rotating electric machine 10 will be described.

[0027] The rotor body 31 is preferably made of a magnetic material, and may be made of a soft magnetic material, magnetic steel plate, or powdered iron core. In addition, a shaft member mounting hole 33 is formed in the central part of the rotor body 31 into which a shaft member 41 constituting the air gap setting means 40 can be inserted.

[0028] The rotor 30 is positioned to rotate axially relative to the stator 20 by the magnetic force generated by passing an electric current through the coil member 23.

[0029] As shown in Figures 6 and 7, the air gap setting means 40 comprises a shaft member 41 and a pair of bearings 42, 42, with one end of the shaft member 41 inserted into the inner ring of the bearing 42. The other end of the shaft member 41 is inserted into the shaft member mounting hole 33 of the rotor body 31, as shown in Figure 5. The shaft member 41 is press-fitted into the rotor 30, and the shaft member 41 and the rotor 30 are configured to rotate around their respective axes.

[0030] The shaft member 41 is a hollow cylindrical member with a through hole 46 that penetrates it in the axial direction. One end of the shaft member 41 in the axial direction (the lower side of the paper in Figure 7) has a bearing inner ring mounting portion 44 that fits onto the inner ring of the bearing 42, and the other end (the upper side of the paper in Figure 7) has a rotor mounting portion 43 that fits into the shaft member mounting hole 33 of the rotor body 31. A stopper 45 is formed between the rotor mounting portion 43 and the shaft member mounting hole 33 along the axial direction, protruding radially outward. The fitting points between the bearing inner ring mounting portion 44 and the shaft member mounting hole 33 may be fixed by press-fitting or adhesive using the inner ring of the bearing 42 or the rotor mounting portion 43.

[0031] The stopper 45 is formed to have a predetermined dimension in the axial direction, and by assembling it so that the rotor body 31 and the inner ring of the bearing 42 abut against the axial edge of the stopper 45, the axial air gap G between the stator 20 and the rotor 30 can be appropriately set.

[0032] Furthermore, by interposing a shim of a predetermined thickness between the stopper 45 and the rotor body 31 or bearing 42, the distance of the air gap G can be easily adjusted, making it possible to easily adjust the output characteristics and efficiency as needed.

[0033] The bearing 42 can be any of the conventionally known bearings, with ball bearings being particularly suitable. Furthermore, by arranging the ball bearings back-to-back, the bearing 42 can withstand radial loads and axial loads in both directions, and the dimension at the point of application can be increased, making it possible to appropriately load moment loads. The outer ring of the bearing 42 is attached to the bearing mounting hole 24 of the stator body 21.

[0034] In this embodiment, the axial gap type rotating electric machine 10 sets the air gap G between the stator 20 and the rotor 30 using the air gap setting means 40, making it possible to have a frameless axial gap type rotating electric machine that does not have a housing covering the stator 20 and the rotor 30. By making it a frameless axial gap type rotating electric machine, the axial gap type rotating electric machine 10 in this embodiment can be made even thinner and smaller.

[0035] Furthermore, since a through hole 46 is formed in the shaft member 41 that penetrates in the axial direction, it becomes easier to secure passages for other members such as cables and motor shafts.

[0036] In addition, although the axial gap type rotating electric machine 10 according to this embodiment described above was explained in the case where the rotor body 31 of the rotor 30 is formed in a disc shape, it is possible to construct an axial gap type rotating electric machine with a higher degree of design freedom by configuring the rotor body 31 so that input-side components such as a reduction gear can be attached to the opposite side of the rotor body 31 where the permanent magnets 32 are not arranged, or by making it possible to directly assemble the input side of a reduction gear to the opposite side.

[0037] Although the axial gap type rotating electric machine 10 according to this embodiment has been described in the case of a brushless motor, by separately preparing sensors and controllers for detecting the rotor position, when applying the axial gap type rotating electric machine 10 according to this embodiment to the joints or torso rotation of robot arms, etc., these components can be appropriately selected according to the product to which they are assembled, making it possible to provide an axial gap type rotating electric machine with greater design flexibility and lower cost.

[0038] Furthermore, although the above embodiment has described the case where the axial gap type rotating electric machine 10 is a three-phase type, the axial gap type rotating electric machine 10 according to this embodiment is not limited to a three-phase type, but may also be configured as a two-phase rotating electric machine.

[0039] Furthermore, although the axial gap type rotating electric machine 10 according to this embodiment has been described in the case where a pair of stators 20 and rotors 30 are formed, a double gap structure in which the rotor 30 or stator 20 is arranged to sandwich the stator 20 or rotor 30 in the axial direction is also possible.

[0040] Furthermore, although the description has focused on the case where the air gap setting means 40 is attached to the central portion of the stator 20 and rotor 30, it may also be attached to the outer circumference of the stator 20 and rotor 30. It is clear from the claims that such modified or improved forms may also fall within the technical scope of the present invention. [Explanation of Symbols]

[0041] 10 Axial gap type rotating electric machine, 20 Stator, 21 Stator body, 22 Projection, 23 Coil member, 24 Bearing mounting hole, 30 Rotor, 31 Rotor body, 32 Permanent magnet, 33 Shaft member mounting hole, 40 Air gap setting means, 41 Shaft member, 42 Bearing, 43 Rotor mounting part, 44 Bearing inner ring mounting part, 45 Stopper, 46 Through hole, G Air gap

Claims

1. An axial gap type rotating electric machine having a stator and a rotor rotatably mounted to the stator with an air gap in the axial direction, The stator comprises a stator body and a plurality of coil members wound around the stator body. The stator body is characterized by having an annular portion, a plurality of protrusions projecting axially from the annular portion and to which the coil member is assembled, and an air gap setting means.

2. In the axial gap type rotating electric machine according to claim 1, The rotor is characterized by comprising a disc-shaped rotor body and a plurality of permanent magnets arranged circumferentially on the surface of the rotor body facing the stator, forming an axial gap type rotating electric machine.

3. In the axial gap type rotating electric machine according to claim 1, The axial gap type rotating electric machine is characterized in that the stator body is formed from a compacted iron core.

4. In the axial gap type rotating electric machine according to claim 1, The air gap setting means comprises either a bearing or a shaft member fitted to the stator body and the other either a bearing or a shaft member fitted to the rotor, wherein the shaft member is assembled to either the inner ring or the outer ring of the bearing, characterized in that it is an axial gap type rotating electric machine.

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