Permanent magnet type rotating motor and magnet positioning structure

Abstract

The present invention aims to provide a permanent magnet type rotating electric machine with improved magnet positioning. The permanent magnet type rotating electric machine (10) comprises a stator (12) and a rotor (11) arranged radially outside the stator (12), wherein the rotor (11) comprises a rotor yoke (17) facing the stator (12) with a gap therebetween, a permanent magnet (19) arranged on a facing surface of the rotor yoke (17) facing the stator (12), and a plate member (20) for positioning the circumferential position of the permanent magnet (19), the facing surface having a slit (18c) recessed radially outward, the plate member (20) having a fitting portion (20a) fitting with the slit (18c) and fixing the circumferential position, and a convex portion (20b) protruding radially inward from the fitting portion (20a), and the circumferential end of the permanent magnet (19) contacts the convex portion (20b).

Description

Technical Field

[0001] The invention relates to a permanent magnet type rotating electrical machine and a magnet positioning structure. Background Art

[0002] In the past, a permanent magnet type rotating electric machine in which a permanent magnet is fixed on the inner peripheral surface of a rotor facing a stator is known, which is an outer rotor type rotating electric machine. Patent document 1 discloses the following structure: a magnet holder made of a non-magnetic material such as resin is processed into a shape that fits with a permanent magnet, and the permanent magnet is positioned by the magnet holder.

[0003] Prior Art Literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent No. 6326662 Summary of the invention

[0006] Problems to be solved by the invention

[0007] However, in Patent Document 1, since a magnet bracket made of non-magnetic materials such as resin is used, there is a problem as follows: the strength of the magnet bracket is problematic. Therefore, it is impossible to increase the tightening force of the screws that fix the magnet bracket. For example, even if the permanent magnet is bonded to the inner circumferential surface of the rotor by an adhesive, the adhesive may peel off, and there is a possibility that the force applied to the permanent magnet in the circumferential direction resists the tightening force of the screws and causes the magnet bracket to move in the circumferential direction. In addition, in order to manufacture resin parts, it is necessary to manufacture an expensive mold, and a mold needs to be manufactured every time the size or shape is changed. Therefore, in the past, there was still room for improvement in magnet positioning.

[0008] An object of the present invention is to provide a permanent magnet type rotating electrical machine with improved magnet positioning.

[0009] Solutions to Solve Problems

[0010] A permanent magnet type rotating electrical machine according to one embodiment of the present invention comprises a stator and a rotor arranged radially outside the stator, wherein the rotor comprises a rotor yoke facing the stator with a gap therebetween, a permanent magnet arranged on a surface of the rotor yoke facing the stator, and a plate member for positioning the circumferential position of the permanent magnet, the facing surface having a slit recessed radially outward, the plate member having an engaging portion engaged with the slit and having a circumferential position fixed, and a convex portion protruding radially inward from the engaging portion, the circumferential end of the permanent magnet being in contact with the convex portion.

[0011] In the permanent magnet type rotating electrical machine of the above-described aspect, the fitting portion is fixed to the rotor yoke by a pin extending in the axial direction.

[0012] In the permanent magnet type rotating electrical machine of the above-described aspect, the facing surface is located radially inward of the fitting portion.

[0013] In the permanent magnet type rotating electrical machine of the above-described aspect, a radially inner surface of the permanent magnet is located radially inward of the convex portion.

[0014] A magnet positioning structure involved in one embodiment of the present invention positions a permanent magnet on the inner circumferential surface of an annular rotor yoke, wherein the magnet positioning structure has a plate member for positioning the circumferential position of the permanent magnet, the inner circumferential surface of the rotor yoke has a slit recessed toward the radial outside, the plate member has an engaging portion that engages with the slit and fixes the circumferential position, and a convex portion protruding radially inward from the engaging portion, and the permanent magnet is positioned by bringing its circumferential end into contact with the convex portion.

[0015] Effects of the Invention

[0016] According to one embodiment of the present invention, a permanent magnet type rotating electrical machine with improved magnet positioning can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a perspective view of a motor according to a first embodiment of the present invention.

[0018] Figure 2 It is a side cross-section of the motor 10 according to the first embodiment.

[0019] Figure 3 This is a diagram showing the motor 10 according to the first embodiment tilted so that the bottom surface is visible relative to the side view.

[0020] Figure 4 This is a side cross-sectional view showing the motor 10 according to the first embodiment cut along a plane passing through the pin 30 and parallel to the axial direction, and is a view showing the vicinity of the pin 30 in an enlarged manner.

[0021] Figure 5 It is extracted Figure 3 The permanent magnet 19 and the plate member 20 are shown in the figure.

[0022] Figure 6 Viewed from the -Y side Figure 5 A three-dimensional view of the permanent magnet 19 and the plate member 20. DETAILED DESCRIPTION

[0023] Below, while referring to the attached Figure 1In the following drawings, in order to facilitate understanding of each configuration, the actual configuration may be different from the reduced ratio and number of each configuration.

[0024] In the drawings, an XYZ coordinate system is appropriately shown as a three-dimensional rectangular coordinate system. In the XYZ coordinate system, the Z axis is parallel to the Figure 1 The X-axis is parallel to the axial direction of the central axis J. Figure 2 The Y-axis direction is a direction perpendicular to both the Z-axis direction and the X-axis direction. For any of the X-axis direction, the Y-axis direction, and the Z-axis direction, the side indicated by the arrow shown in the figure is set as the + side, and the opposite side is set as the - side.

[0025] In addition, in the following description, the positive side of the Z-axis direction (+Z side) is referred to as "one side", and the negative side of the Z-axis direction (-Z side) is referred to as "the other side". In addition, one side and the other side are names used simply for explanation, and do not limit the actual positional relationship and direction. In addition, unless otherwise specified, the direction parallel to the center axis J (Z-axis direction) is simply referred to as "axial direction", the radial direction centered on the center axis J is simply referred to as "radial direction", and the circumferential direction centered on the center axis J, that is, the direction around the center axis J, is simply referred to as "circumferential direction". The side radially closer to the center axis J is referred to as the "radial inner side", and the side farther from the center axis J is referred to as the "radial outer side".

[0026] In addition, in the present specification, "extending in the axial direction" refers not only to extending strictly in the axial direction (Z-axis direction), but also to extending in a direction inclined within a range of less than 45° relative to the axial direction. In addition, in the present specification, "extending in the radial direction" refers not only to extending strictly in the radial direction, i.e., in a direction perpendicular to the axial direction (Z-axis direction), but also to extending in a direction inclined within a range of less than 45° relative to the radial direction. In addition, "parallel" refers not only to being strictly parallel, but also to being inclined within a range of less than 45°.

[0027] <First Embodiment>

[0028] Figure 1 It is a perspective view of a motor according to a first embodiment of the present invention. Figure 1 The motor 10 is an example of a permanent magnet type rotating electrical machine. Figure 2 FIG. 1 is a side cross-section of the motor 10 according to the first embodiment. Figure 1 In the figure, the fixed shaft 13 and the bearings 14 and 15 are omitted.

[0029] The motor 10 includes: a fixed shaft 13 extending along the central axis J; a stator 12; and a rotor 11 arranged radially outside the stator 12 with a gap therebetween. Since the structure of the stator 12 is not an essential part of the present invention, the detailed structure of the stator 12 is omitted. The fixed shaft 13 is fixed to the stator 12, for example. The rotor 11 has a hollow shaft portion 16 on the radial inside. The fixed shaft 13 penetrates the hollow shaft portion 16. The rotor 11 is axially supported by the fixed shaft 13 via bearings 14 and 15 so as to be rotatable about the central axis J as the rotation center.

[0030] The rotor 11 has a rotor yoke 17 facing the stator 12 with a gap therebetween. The rotor yoke 17 is an annular member. The rotor yoke 17 is formed of laminated steel plates formed by laminating electromagnetic steel plates in the axial direction. The rotor yoke 17 may also be a structure formed by hollowing out an iron core instead of laminated steel plates. The rotor 11 has permanent magnets 19 (see Figure 3 ). The permanent magnet 19 is fixed to the inner circumferential surface 18a of the rotor yoke 17. The rotor yoke 17 has an inner circumferential surface 18a and an inner circumferential surface 18b. The inner circumferential surface 18a is an example of a facing surface facing the stator 12. The inner circumferential surface 18b is located radially inward of the inner circumferential surface 18a. It can also be formed so that one axial end of the permanent magnet 19 contacts the radial step portion of the inner circumferential surface 18b and the inner circumferential surface 18a.

[0031] Figure 3 This is a diagram showing the bottom surface of the motor 10 in a tilted manner relative to the side view of the first embodiment. The inner peripheral surface 18a of the rotor yoke 17 has a slit 18c that is recessed toward the radial outside. The slit 18c is formed over the entire circumference of the inner peripheral surface 18a. The slit 18c can also be formed by cutting using a lathe or the like. The slit 18c can also be formed by stacking electromagnetic steel sheets having an inner diameter larger than that of the inner peripheral surface 18a at the axial position where the slit 18c is to be formed.

[0032] The rotor 11 has a plate member 20. The plate member 20 is fitted into the slit 18c of the rotor yoke 17. The plate member 20 positions the circumferential position of the permanent magnet 19. The permanent magnet 19 is arranged over the entire circumference, but Figure 3 Only five permanent magnets 19 are shown. The plate member 20 is arranged over the entire circumference, but Figure 3 Only three plate members 20 are shown in the figure. The rotor yoke 17 has a through hole 11a into which a pin 30 is inserted, and the pin 30 fixes the plate member 20 fitted in the slit 18c. The through hole 11a extends in the axial direction.

[0033] Figure 4This is a side sectional view showing the motor 10 of the first embodiment cut along a plane passing through the pin 30 and parallel to the axial direction, and is a view showing the vicinity of the pin 30 in an enlarged manner. The through hole 11a penetrates from the other axial end of the rotor yoke 17 toward the slit 18c. The through hole 11a may also extend from the slit 18c further toward one axial side of the rotor yoke 17. The plate member 20 has a through hole 20c extending in the axial direction. The through hole 11a is connected to the through hole 20c by fitting the plate member 20 with the slit 18c. The pin 30 is inserted into the connected through hole 11a and the through hole 20c, thereby fixing the plate member 20 to the slit 18c.

[0034] Figure 5 It is extracted Figure 3 The permanent magnet 19 and the plate member 20 are shown in the figure. Figure 6 Viewed from the -Y side Figure 5 3D view of the permanent magnet 19 and the plate member 20. The permanent magnet 19 is in a cubic shape. A radially inner surface 19a of the permanent magnet 19 faces the stator 12. A radially outer surface 19b of the permanent magnet 19 faces the inner peripheral surface 18a of the rotor yoke 17.

[0035] The plate member 20 has a fitting portion 20a and a convex portion 20b protruding radially inward from the fitting portion 20a. The fitting portion 20a is a flat plate-shaped member. The axial width of the slit 18c is substantially equal to the axial thickness of the plate member 20, and the fitting portion 20a fits with the slit 18c. The fitting portion 20a has a through hole 20c that penetrates in the axial direction. In the present embodiment, one plate member 20 has three convex portions 20b. The number of convex portions 20b provided in one plate member 20 may also be other than three. In the present embodiment, one plate member 20 has two through holes 20c. The number of through holes 20c provided in one plate member 20 may also be other than two. The fitting portion 20a is embedded in the slit 18c, connects the through hole 11a of the rotor yoke 17 with the through hole 20c, and inserts a pin, thereby fixing the circumferential position. Alternatively, the fitting portion 20a in the slit 18c may be screwed to the rotor yoke 17. As the pin for connecting the through hole 11a and the through hole 20c, a pin that contacts the through hole 11a and the through hole 20c without a gap is preferred, and for example, a parallel pin or a knock pin may be used.

[0036] The circumferential length between a certain convex portion 20b and another convex portion 20b adjacent to the certain convex portion 20b is substantially equal to the circumferential length of the permanent magnet 19, and the permanent magnet 19 is fitted between the convex portions 20b. The permanent magnet 19 is fixed in the circumferential position by contacting the circumferential end portions with the convex portions 20b.

[0037] The plate member 20 of this embodiment is used to position three permanent magnets 19 by one plate member 20. When a certain plate member 20 and another plate member 20 different from the certain plate member 20 are arranged in the circumferential direction, one permanent magnet 19 can be arranged between the convex portion 20b of the certain plate member 20 that is closest to the other plate member 20 and the convex portion 20b of the other plate member 20 that is closest to the certain plate member 20 for positioning. In this case, the circumferential length from the convex portion 20b that is closest to the circumferential outer side among the convex portions 20b of the plate member 20 to the circumferential end of the fitting portion 20a on the side close to the convex portion 20b is less than 1 / 2 of the circumferential length of the permanent magnet 19.

[0038] The plate member 20 is, for example, a metal plate. Therefore, the tightening force between the fitting portion 20a and the rotor yoke 17 can be increased. When the plate member 20 is made of a non-magnetic material, the magnetic flux density decreases due to the decrease in the magnetic permeability of the magnet in the plate member 20 portion. Therefore, the plate member 20 is preferably made of a magnetic material. The material of the plate member 20 is, for example, SPHC. The plate member 20 is preferably made of a material that satisfies the strength (stress, surface pressure) relative to the force applied to the plate member 20.

[0039] The inner peripheral surface 18a of the rotor yoke 17 is located radially inwardly of the fitting portion 20a. Alternatively, the fitting portion 20a does not protrude radially inwardly from the inner peripheral surface 18a. This facilitates fixing of the permanent magnet 19 to the inner peripheral surface 18a by adhesive.

[0040] The radially inner side surface of the permanent magnet 19, i.e., the surface 19a, is located radially inwardly of the protrusion 20b. Alternatively, the protrusion 20b does not protrude radially inwardly compared to the surface 19a of the permanent magnet 19. Thus, the protrusion 20b will not protrude in the gap between the rotor 11 and the stator 12. The protrusion amount of the protrusion 20b from the inner peripheral surface 18a toward the radial inside is the protrusion amount that satisfies the strength (stress, surface pressure) required to fix the circumferential position of the permanent magnet 19. If the length of the protrusion 20b extending radially inward is increased, since the plate member 20 is a magnetic material, the leakage flux will increase and the magnetic flux density of the gap will decrease. Therefore, it is preferred that the radial length of the protrusion 20b is the minimum height within the range that satisfies the strength mechanically.

[0041] When manufacturing the rotor 11 of the present embodiment, first, the slit 18c is formed in the annular rotor yoke 17. Next, the plate member 20 is inserted into the slit 18c and fixed by a pin. Next, an adhesive is applied to the inner peripheral surface 18a of the rotor yoke 17, and the permanent magnet 19 is positioned with reference to the convex portion 20b of the plate member 20, and the permanent magnet 19 is bonded and fixed to the inner peripheral surface 18a.

[0042] According to the present embodiment, the time required for forming the slit 18c is short, and the processing time can be shortened. In addition, according to the present embodiment, the plate member 20 can be made relatively easily by, for example, laser processing. In addition, according to the present embodiment, since the part for determining the position of the permanent magnet 19 is the plate member 20 of a metal plate, there is no need for a mold like resin molding, and there is no mold manufacturing cost and cost for changing the size or shape. In addition, according to the present embodiment, the plate member 20 is held on the rotor yoke 17 by a pin, so the plate member 20 does not move when subjected to motor torque.

[0043] The present invention is not limited to the above-mentioned embodiments, and various improvements and design changes can be made without departing from the scope of the concept of the present invention. In addition, it should be considered that the embodiments disclosed this time are illustrative in all aspects and are not restrictive. The scope of the present invention is not represented by the above-mentioned description, but by the claims, and is intended to include all changes within the meaning and scope equivalent to the claims.

[0044] This application claims the priority based on Japanese patent application No. 2021-116128 for which it applied on July 14, 2021, and cites all the contents described in the Japanese patent application.

[0045] Description of Reference Numerals

[0046] 10 ...motor, 11 ...rotor, 12 ...stator, 13 ...fixed shaft, 17 ...rotor yoke, 18c ...slit, 19 ...permanent magnet, 20 ...plate member.

Claims

1. A permanent magnet type rotating electrical machine comprising a stator and a rotor arranged radially outside the stator, wherein: The rotor comprises: a rotor yoke facing the stator with a gap therebetween; a permanent magnet disposed on a surface of the rotor yoke facing the stator; and a plate member for positioning the circumferential position of the permanent magnet. The facing surface has a slit recessed toward the radial outside, The plate member includes: a fitting portion that fits into the slit and is fixed in a circumferential position; and a convex portion that protrudes radially inward from the fitting portion. The circumferential end of the permanent magnet contacts the convex portion. One axial end of the protrusion is located closer to the other axial side than one axial end of the permanent magnet, and the other axial end of the protrusion is located closer to the one axial side than the other axial end of the permanent magnet. The plate member is divided in the circumferential direction so that the fitting portion can be fitted into the slit from the facing surface.

2. The permanent magnet type rotating electrical machine according to claim 1, wherein: The fitting portion is fixed to the rotor yoke by a pin extending in the axial direction.

3. The permanent magnet type rotating electrical machine according to claim 1 or 2, wherein: The facing surface is located radially inward of the fitting portion.

4. The permanent magnet type rotating electrical machine according to claim 1, wherein: The radially inner surface of the permanent magnet is located radially inward of the convex portion.

5. A magnet positioning structure, which positions a permanent magnet on the inner peripheral surface of an annular rotor yoke, wherein: The magnet positioning structure comprises a plate member for positioning the circumferential position of the permanent magnet. The inner peripheral surface of the rotor yoke has a slit recessed toward the radial outside. The plate member includes: a fitting portion that fits into the slit and is fixed in a circumferential position; and a convex portion that protrudes radially inward from the fitting portion. The permanent magnet is positioned by making its circumferential end portion contact the protrusion. One axial end of the protrusion is located closer to the other axial side than one axial end of the permanent magnet, and the other axial end of the protrusion is located closer to the one axial side than the other axial end of the permanent magnet. The plate member is divided in the circumferential direction so that the fitting portion can be fitted into the slit from the inner peripheral surface.

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