JP2022081294A - motor - Google Patents

Abstract

To improve efficiency of a motor by reducing reduction in circularity of a rotor core and leakage of magnetic flux.SOLUTION: A motor has a rotor and a stator. The rotor includes a rotor core 10, magnets 30 attached to the rotor core and a cylindrical member 50 located on the outer periphery of the rotor core and the magnets. The rotor core has a lamination structure obtained by laminating a plurality of steel cores formed of a soft magnetic material such as a silicon steel plate and protrusions 11 protruded in a radial direction are formed separably in a circumferential direction. Each of the magnets is arranged between the protrusions of the rotor core and the cylindrical member is fixed on the protrusions.SELECTED DRAWING: Figure 4

Description

The present invention relates to a motor.

In rotors of rotary electric machines such as motors and generators, surface magnet type (SPM) rotors in which a plurality of magnets are mounted on the outer periphery of the rotor core are often used. At that time, in order to prevent the segment magnet attached to the rotor core from scattering, a technique is known in which the rotor core to which the magnet is mounted is covered with a cover.

Japanese Unexamined Patent Publication No. 2016-92858 Japanese Unexamined Patent Publication No. 2013-188005 Japanese Unexamined Patent Publication No. 2000-270503

However, when magnets are mounted on the outer circumference of the rotor core, the outer diameter of the rotor may be affected by the thickness of each magnet. In this case, it becomes difficult to guarantee the roundness accuracy of the rotor due to the error in the thickness of the magnet. Further, when a plurality of magnets are arranged close to each other, the magnetic flux does not flow toward the stator core provided on the outside of the rotor, and easily leaks to the adjacent magnets. Such a decrease in roundness accuracy or leakage of magnetic flux may cause a decrease in the efficiency of the torque generated with respect to the current applied to the motor.

On one side, it aims to provide a motor that can improve efficiency.

In one embodiment, the motor comprises a rotor and a stator. The rotor includes a rotor core, a magnet attached to the rotor core, and a cylindrical member located on the rotor core and the outer periphery of the magnet. The rotor core has a convex portion that protrudes in the radial direction. The cylindrical member is fixed to the convex portion.

According to one embodiment, efficiency can be improved.

FIG. 1 is a perspective view showing an example of a rotor according to the first embodiment. FIG. 2 is a plan view showing an example of a steel plate constituting the rotor core according to the first embodiment. FIG. 3 is a cross-sectional view showing an example of a rotor core to which a magnet according to the first embodiment is attached. FIG. 4 is a cross-sectional view showing an example of a rotor core inserted through the cylindrical member according to the first embodiment. FIG. 5 is an enlarged cross-sectional view showing the positional relationship between the convex portion of the rotor core and the magnet according to the first embodiment. FIG. 6 is a cross-sectional view showing an example of a rotor inserted through the stator according to the first embodiment. FIG. 7 is an enlarged cross-sectional view showing the positional relationship between the convex portion and the void of the rotor core according to the first embodiment. FIG. 8 is a diagram illustrating a flow of magnetic flux in the motor according to the first embodiment. FIG. 9 is a perspective view showing an example of a press-fitting process of the rotor core into the cylindrical member according to the first embodiment. FIG. 10 is a perspective view showing an example of a cylindrical member into which the rotor core is press-fitted according to the first embodiment. FIG. 11 is a cross-sectional view showing an example of the rotor according to the first embodiment.

Hereinafter, embodiments of the motor disclosed in the present application will be described in detail with reference to the drawings. The relationship between the dimensions of each element in the drawing, the ratio of each element, etc. may differ from the reality. Even between the drawings, there may be parts where the relationship and ratio of the dimensions are different from each other. In each drawing, in order to make the explanation easy to understand, a coordinate system including at least one of the axial direction (rotational axis direction of the motor MT), the radial direction, and the circumferential direction in the motor MT described later may be illustrated. .. Further, in the following, the rotation axis direction of the motor MT may be simply referred to as "axial direction".

FIG. 1 is a perspective view showing an example of a rotor according to the first embodiment. As shown in FIG. 1, the rotor RT in the present embodiment is formed of a rotor core 10, a bottom plate 20, a plurality of magnets 30, and a cylindrical member 50. The cylindrical member 50 is an example of a cylindrical member.

The rotor core 10 has a laminated structure obtained by laminating a plurality of steel plate cores formed of a soft magnetic material such as a silicon steel plate. FIG. 2 is a plan view showing an example of a steel plate constituting the rotor core according to the first embodiment. As shown in FIG. 2, a hole 12 for inserting a shaft (not shown) is provided in the central portion of the steel plate constituting the rotor core 10. Further, in the rotor core 10 of the present embodiment, a plurality of convex portions 11a to 11h are formed so as to be separated from each other in the circumferential direction. When the convex portions 11a to 11h are expressed without distinction, they may be simply referred to as the convex portions 11. Further, on each steel plate constituting the rotor core 10, for example, a boss portion 13 for fixing to another steel plate by caulking is formed. The rotor core 10 may be further formed with a lightening portion 14 in order to reduce the inertia of the rotating body.

Returning to FIG. 1, the bottom plate 20 is a circular plate material formed of, for example, non-magnetic stainless steel. The diameter of the bottom plate 20 is formed, for example, to be the same as that of the cylindrical member 50 or slightly larger than that of the cylindrical member 50. The bottom plate 20 is joined to one side in the axial direction of the rotor core 10 having a laminated structure, and functions as a retaining member for suppressing the falling off of the cylindrical member 50. The bottom plate 20 is an example of the bottom portion.

The magnet 30 is, for example, a neodymium sintered segment magnet. In the present embodiment, a plurality of magnets 30 are arranged apart from each other in the circumferential direction between the convex portions 11 of the rotor core 10. In the following, when a plurality of magnets 30 are distinguished and expressed, they may be referred to as magnets 31 to 38.

FIG. 3 is a cross-sectional view showing an example of a rotor core to which a magnet according to the first embodiment is attached. As shown in FIG. 3, for example, the magnet 31 is arranged between the convex portion 11a and the convex portion 11b of the rotor core 10, and the magnet 32 is arranged between the convex portion 11b and the convex portion 11c of the rotor core 10. Magnet.

The cylindrical member 50 is formed of, for example, the same non-magnetic stainless steel as the bottom plate 20, and functions as a rotor cover that covers the outer peripheral surfaces of the rotor core 10 and the magnet 30 in the radial direction. One of the cylindrical members 50 in the axial direction is in contact with the bottom plate 20. One of the cylindrical members 50 in the axial direction is located outward in the axial direction from one end in the axial direction of the rotor core 10 and the magnet 30 when the rotor core 10 is press-fitted, as will be described later. In this embodiment, the cylindrical member 50 has no bottom surface at either end in the axial direction.

In the present embodiment, the rotor core 10 to which the bottom plate 20 and the magnet 30 are mounted constitutes the rotor RT by being press-fitted into the cylindrical member 50. FIG. 4 is a cross-sectional view showing an example of a rotor core inserted through the cylindrical member according to the first embodiment. When the rotor core 10 is press-fitted into the cylindrical member 50, the roundness accuracy of the cylindrical member 50 is determined by the dimension of the portion in contact with the inner surface of the cylindrical member 50, for example, the convex portion 11 (11a) of the rotor core 10 shown in FIG. It depends on the distance H1 from the center C. In the example shown in FIG. 4, the distance H2 between the outer peripheral surface of the magnet 30 and the center C of the rotor core 10 is the distance obtained by combining the thickness T of the magnet 30 and the radius of the partial IC excluding the convex portion 11 of the rotor core 10. Become.

In the present embodiment, as shown in FIG. 4, the inner peripheral surface of the cylindrical member 50 is in contact with the convex portions 11a to 11h of the rotor core 10. Further, the radial dimension T of the magnet 30 shown in FIG. 4 is smaller than the radial dimension Ha of the convex portion 11 shown in FIG. In this case, the roundness accuracy of the rotor RT is not affected by the distance H2 between the outer peripheral surface of the magnet 30 and the center C of the rotor core 10.

The thickness of the magnet 30 may vary due to design errors and the like. In this case, when the inner surface of the cylindrical member 50 comes into contact with the magnet 30, the roundness accuracy of the cylindrical member 50 is impaired due to the variation in the thickness of the magnet 30. For example, when the rotor core 10 does not have the convex portion 11 and the partial IC excluding the convex portion 11 of the rotor core 10 is formed in a perfect circular shape, the roundness accuracy of the rotor RT is inversely proportional to the variation in the thickness of the magnet 30. do.

On the other hand, it is easier to suppress the variation in the dimensions of the convex portions 11a to 11h of the rotor core 10 in the radial direction in the present embodiment than to suppress the variation in the thickness of the magnet 30. Therefore, when the distance H1 between the convex portion 11 of the rotor core 10 and the center C of the rotor core 10 shown in FIG. 3 is larger than the distance H2 between the outer peripheral surface of 30 arranged on the rotor core 10 and the center C of the rotor core 10. The roundness accuracy of the rotor RT can be guaranteed.

FIG. 5 is an enlarged cross-sectional view showing the positional relationship between the convex portion of the rotor core and the magnet according to the first embodiment. FIG. 5 is an enlarged view of the portion shown in the frame F1 of FIG. In FIG. 5, the height Ha of the portion of the convex portion 11a (the height obtained by subtracting the radius of the partial IC excluding the convex portion 11 of the rotor core 10 from the distance H1) is the height Hg and the convex portion of the portion of the convex portion 11gf. It is formed so as to be substantially the same as the height Hh of the portion of 11h. That is, the distance between the convex portion 11g of the rotor core 10 and the center C and the distance between the convex portion 11h of the rotor core 10 and the center C are substantially the same as the distance H1 between the convex portion 11a of the rotor core 10 and the center C. ..

Further, as shown in FIG. 5, the thickness Ty of the magnet 37 and the thickness Tx of the magnet 38 are both smaller than the height Ha of the convex portion 11a. That is, the rotor core 10 is press-fitted into the cylindrical member 50 so that the convex portions 11a to 11h are in contact with the inner peripheral surface of the cylindrical member 50.

In this case, when the height of the magnet 30 is low, the cylindrical member 50 may be pulled by each convex portion 11 and deformed, so that the inner peripheral surface may come into contact with the magnet 30. In this case, for example, if the thickness Ty of the magnet 37 and the thickness Tx of the magnet 38 vary, the portion 5y of the cylindrical member 50 facing the magnet 37 and the portion 5x facing the magnet 38 are shown in FIG. There is a difference in the size of the gap between the magnet 30 and the cylindrical member 50. However, the roundness accuracy of the cylindrical member 50 as a whole is ensured by supporting each portion of the inner peripheral side surface of the cylindrical member 50 by a plurality of convex portions 11a to 11h having substantially the same height. ..

FIG. 6 is a cross-sectional view showing an example of a rotor inserted through the stator according to the first embodiment. As shown in FIG. 6, the rotor RT faces the inner peripheral surface of the stator ST on the outer peripheral surface of the cylindrical member 50. In this case, even if there is a difference in the gap between the magnet 30 and the stator ST due to the variation in the thickness of the magnet 30, the outer peripheral side surface of the rotor RT that rotates facing the inner peripheral side surface of the stator ST. The roundness accuracy of is guaranteed.

Further, the convex portion 11 of the rotor core 10 suppresses the leakage of magnetic flux between the adjacent magnets 30. In the rotor RT mounted on the stator ST shown in FIG. 6, the magnetic flux is preferably directed outward in the radial direction and toward the adjacent magnet 31 as shown by the arrow M. In that case, it is desired that the leakage of the magnetic flux as shown by the arrow MM is suppressed.

FIG. 7 is an enlarged cross-sectional view showing the positional relationship between the convex portion and the void of the rotor core according to the first embodiment. FIG. 7 is an enlarged view of the portion shown in the frame F2 of FIG. As shown in FIG. 7, the convex portion 11a is located between the north pole of the magnet 38 on one side in the circumferential direction (left side in the drawing) and the south pole of the magnet 37 on the other side in the circumferential direction (right side in the drawing). To position. Further, a gap FB is formed between the convex portion 11a and the magnet 37.

In FIG. 7, the leakage of the magnetic flux as shown by the arrow MM is blocked by the gap FB formed between the entire radial direction of the convex portion 11 and the magnet 30. That is, the gap FB acts as a flux barrier. In this case, the flow of magnetic flux as shown in FIG. 8 is formed. FIG. 8 is a diagram illustrating a flow of magnetic flux in the motor according to the first embodiment. In FIG. 8, the pattern shown in the portion P1 shows a portion having a high magnetic flux density, and the pattern shown in the portion P2 shows a portion having a relatively low magnetic flux density, that is, a portion having a small magnetic flux. As shown in FIG. 8, the magnetic flux density is high in the portion indicated by the arrow M in FIG. 6, and the magnetic flux density is relatively low in the portion indicated by the arrow MM in FIG. As described above, in the present embodiment, leakage of magnetic flux between adjacent magnets 30 is suppressed, and the ease of assembling the rotor is improved.

Returning to FIG. 4, the rotor core 10 in which the magnet 30 is arranged is press-fitted into the cylindrical member 50 as described above. FIG. 9 is a perspective view showing an example of a press-fitting process of the rotor core into the cylindrical member according to the first embodiment. As shown in FIG. 9, the rotor core 10 is press-fitted in the direction indicated by the arrow. That is, the rotor core 10 is press-fitted into the cylindrical member 50 on the side opposite to the side to which the bottom plate 20 is joined in the axial direction.

As shown in FIG. 9, the axial length L2 of the cylindrical member 50 is larger than the axial length L1 of the rotor core 10. In this case, in the cylindrical member 50, in a state where the rotor core 10 is press-fitted and one end in the axial direction is joined to the bottom plate 20, the other end in the axial direction is the other end of the rotor core 10 as shown in FIG. It extends from the end of. FIG. 10 is a perspective view showing an example of a cylindrical member into which the rotor core is press-fitted according to the first embodiment. As shown in FIG. 10, an extension portion OH is formed between the cylindrical member 50 into which the rotor core 10 is press-fitted and the end portion of the rotor core 10 opposite to the bottom plate 20 in the axial direction. The caulking portion 51, which is a protruding portion protruding inward in the radial direction shown in FIG. 1, is formed at a position axially opposed to the magnet 30 in the extension portion OH.

FIG. 11 is a cross-sectional view showing an example of the rotor according to the first embodiment. As shown in FIG. 11, the caulking portion 51 is formed, for example, in the vicinity of the central portion in the circumferential direction of the magnet 31. That is, in the present embodiment, the caulking portion 51 is formed at a position where the outer peripheral side surface of the magnet 30 and the inner peripheral side surface of the cylindrical member 50 are in contact with each other. Further, as described above, one end of the cylindrical member 50 in the axial direction is joined to the bottom plate 20. This makes it possible to prevent the magnet 30 from falling off in the axial direction.

As described above, the motor MT in this embodiment has a rotor RT and a stator ST. The rotor RT includes a rotor core 10, a magnet 30 attached to the rotor core 10, and a cylindrical member 50 located on the outer periphery of the rotor core 10 and the magnet 30. The rotor core 10 has a convex portion 11 protruding in the radial direction, and the tubular member 50 is fixed to the convex portion 11. Thereby, the efficiency of the motor MT can be improved.

By the way, although the embodiment of the present invention has been described so far, the present invention may be implemented in various different forms other than the above-described embodiment. For example, the configuration in which the magnet 30 has a gap between the magnet 30 and the inner peripheral surface of the cylindrical member 50 has been described, but the embodiment is not limited to this. As long as it does not reduce the roundness of the rotor RT, for example, the structure may be such that the inner peripheral surface of the cylindrical member 50 and the magnet 30 are in contact with each other.

Further, the caulking portion 51 may be formed at a position facing other than the vicinity of the central portion in the circumferential direction of the magnet 30 as long as it acts as a retaining mechanism for the magnet 30. Further, the caulking portion 51 and the magnet 30 do not necessarily have a one-to-one correspondence. For example, a plurality of caulking portions 51 are formed for one magnet 30, or every other magnet 30 is formed in the circumferential direction. The caulking portion 51 may be provided on the magnet 30. That is, a magnet 30 without the caulking portion 51 may be provided next to the magnet 30 with the caulking portion 51.

Further, the present invention is not limited to the above embodiments. The present invention also includes those configured by appropriately combining the above-mentioned constituent elements. Further, further effects and modifications can be easily derived by those skilled in the art. Therefore, the broader aspect of the present invention is not limited to the above-described embodiment, and various modifications can be made.

10 Rotor core, 11 (11a-11h) convex part, 12 hole part, 13 boss part, 14 lightening part, 20 bottom plate, 30 (31-38) magnet, 50 cylindrical member, 51 caulking part, RT rotor, ST stator, MT motor

Claims (7)

It has a rotor and a stator,
The rotor is
With the rotor core
The magnet attached to the rotor core and
The rotor core and the tubular member located on the outer periphery of the magnet are provided.
The rotor core has a convex portion protruding in the radial direction, and the rotor core has a convex portion.
The tubular member is a motor fixed to the convex portion. The motor according to claim 1, wherein the maximum distance between the radial outer end of the convex portion and the center of the rotor core is larger than the maximum distance between the radial outer end of the magnet and the center of the rotor core. The motor according to claim 1 or 2, wherein the motor has a plurality of the magnets, and the convex portion is arranged between the plurality of magnets. The motor according to any one of claims 1 to 3, which has a gap between the convex portion and the magnet. The motor according to claim 4, wherein the gap is formed between the entire radial direction of the convex portion and the magnet. The rotor further comprises a bottom at one end in the axial direction of the rotor core.
The motor according to any one of claims 1 to 5, wherein one end of the tubular member in the axial direction is in contact with the bottom. The axial length of the tubular member is larger than the axial length of the magnet.
The motor according to claim 6, wherein a protrusion is formed at the other end of the tubular member at a position facing the magnet.

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