Rotor and rotary electric machine

Abstract

This rotor comprises: a first punched hole which has a cross-sectional shape that is rounded at the vertices of a quadrilateral and is symmetrical with respect to a symmetry plane passing through the rotation axis; a second punched hole which has a cross-sectional shape that is rounded at the vertices of a figure surrounded by two line segments and a curve or a line segment connecting points on the two line segments, is symmetrical with respect to a symmetry plane different from the symmetry plane of the first punched hole, and is formed such that the point farthest from the rotation axis among the points along the rounded portion thereof is farther away from the rotation axis than is the point closest to the rotation axis among the points along the rounded portion of the first punched hole; and a third punched hole which has a cross-sectional shape that is rounded at the vertices of a figure surrounded by two line segments and a curve or a line segment connecting points on the two line segments, is symmetrical with respect to the symmetry plane of the second punched hole, and is formed such that the point closest to the rotation axis among the points along the rounded portion thereof is located closer to the rotation axis than is the point farthest from the rotation axis among the points along the rounded portion of the first punched hole.

Description

Rotor and Rotating Electrical Machine

[0001] The present invention relates to a rotor and a rotating electrical machine.

[0002] A rotor core of a rotating electrical machine such as a motor or a generator includes a plurality of plate-shaped members stacked in the direction of the rotation shaft of the rotor. In order to concentrate magnetic flux on each pole of the rotor and reduce eddy current loss in the rotor, the plate-shaped members are often provided with hollow holes penetrating in the direction of the rotation shaft. Furthermore, the hollow holes enable reduction of the manufacturing cost of the rotating electrical machine and weight reduction of the rotating electrical machine by reusing scrap materials of the plate-shaped members. As a document disclosing hollow holes formed in a rotor, Patent Document 1 can be cited, for example.

[0003] Japanese Unexamined Patent Publication No. 2021-136785

[0004] However, in general, the hollow holes reduce the mechanical strength of the rotor core. Therefore, the rotor core may be broken due to the hollow holes under stresses such as the stress generated when the shaft is fitted into the rotor, the stress generated by the centrifugal force of rotor rotation, and the stress generated when the rotor rotates relative to the shaft. Furthermore, in the rotor according to Patent Document 1, the width of the first bridges between the first holes arranged in the first hole row is narrower than the width of the second bridges between the second holes arranged in the second hole row. Therefore, in the rotor according to Patent Document 1, these stresses concentrate on the first bridges, which may cause the first bridges to break.

[0005] Accordingly, an object of the present invention is to provide a rotor and a rotating electrical machine that can alleviate stress applied to the rotor core while enjoying the advantages of providing hollow holes in the rotor core.

[0006] To solve the above-mentioned problems, the rotor of the present invention has a first cutout, the shape of which is a cross-section of a plane perpendicular to the rotor's axis of rotation, in which the four vertices of a rectangle are rounded and the shape is symmetrical with respect to the plane of symmetry passing through the axis of rotation, and the shape of which is a cross-section of a plane perpendicular to the axis of rotation, in which the three vertices of a figure enclosed by two line segments and a curve or line segment connecting points on the two line segments are rounded and the plane is different from the plane of symmetry of the first cutout, the shape is symmetrical with respect to the plane of symmetry passing through the axis of rotation, and the point on the curve that is furthest from the axis of rotation The invention provides a second punch hole in which the farthest point is located further from the axis of rotation than the point on the radius of the first punch hole that is closest to the axis of rotation, and a third punch hole in which the cross-sectional shape of a plane perpendicular to the axis of rotation is such that the three vertices of a figure enclosed by two line segments and a curve or line segment connecting two points on the two line segments are rounded, the shape is symmetrical with respect to the plane of symmetry of the second punch hole, and the point on the radius that is closest to the axis of rotation is located closer to the axis of rotation than the point on the radius of the first punch hole that is furthest from the axis of rotation.

[0007] In the rotor of the present invention, the second hole has a shape in which the cross-sectional shape of a figure formed by a plane perpendicular to the axis of rotation is enclosed by two line segments and an arc centered on a point on the axis of rotation, and the three vertices of this figure are rounded.

[0008] The rotor of the present invention further comprises a first bridge portion sandwiched between one side of the first cutout and one of the two line segments of the second cutout in a cross-section perpendicular to the axis of rotation, and a second bridge portion sandwiched between one side of the first cutout and one of the two line segments of the third cutout in a cross-section perpendicular to the axis of rotation, wherein the width W1 of the first bridge portion and the width W2 of the second bridge portion satisfy the relation 0.8 × W1 ≤ W2 ≤ W1.

[0009] In the rotor of the present invention, the interior angle of the vertex closest to the axis of rotation in the first cutout hole is greater than the interior angle of the vertex furthest from the axis of rotation in the first cutout hole.

[0010] The rotating electric machine of the present invention comprises one of the rotors described above.

[0011] According to the present invention, it is possible to enjoy the benefits of forming holes in the rotor core while mitigating the stress applied to the rotor core.

[0012] This is a cross-sectional view of the rotor core according to the embodiment, taken from a plane perpendicular to the axis of rotation. This is a diagram showing the details of the first hole, second hole, third hole, first bridge section, second bridge section, and third bridge section according to the embodiment.

[0013] Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In the embodiments, a motor will be used as an example of a rotating electric machine. Figure 1 is a cross-sectional view of the rotor core according to the embodiment, taken from a plane perpendicular to the axis of rotation. In addition to the rotor core 1 shown in Figure 1, the motor according to the embodiment includes a housing, a shaft, a stator core, and a coil.

[0014] The housing is a cylindrical member to which the stator core, coils, etc. are attached, and the shaft, rotor core 1, etc. are housed inside. The shaft is a rod-shaped member supported in a manner that allows it to rotate around the rotation axis X shown in Figure 1. The shaft is also fitted into a shaft insertion hole formed in the rotor core 1. For example, the shaft is fixed into the shaft insertion hole by shrink fitting, shrink fitting, or press fitting. The stator core is a cylindrical member attached to the housing and has multiple teeth formed thereon. The coil is inserted between adjacent teeth. The stator core and coil constitute the stator, and when the coil is energized, it generates the magnetic force necessary to rotate the shaft and rotor core 1 around the rotation axis X.

[0015] As shown in Figure 1, the rotor core 1 has a magnet insertion hole 11, a magnet insertion hole 12, a first cutout hole 21, a second cutout hole 22, and a third cutout hole 23. The rotor core 1 is manufactured by stacking plate-shaped members in the direction of the rotation axis X.

[0016] The magnet insertion holes 11 and 12 are holes into which magnets are inserted. The rotor core 1 forms the rotor together with these magnets. Furthermore, the magnet insertion holes 11 and 12 do not overlap with the first cutout hole 21, the second cutout hole 22, and the third cutout hole 23 in the circumferential direction of a circle centered on a point on the rotation axis X.

[0017] Figure 2 shows details of the first, second, and third punch holes, the first bridge section, the second bridge section, and the third bridge section according to the embodiment. The first punch hole 21 has a cross-sectional shape in a plane perpendicular to the rotation axis X of the rotor, with rounded corners at the four vertices of a rectangle, and is symmetrical with respect to the plane of symmetry E passing through the rotation axis X. Furthermore, the interior angle A211 of the vertex closest to the rotation axis X in the first punch hole 21 is greater than the interior angle A212 of the vertex furthest from the rotation axis X in the first punch hole 21. Moreover, the shape of the first punch hole 21 is constant regardless of its position in the direction of the rotation axis X. In this embodiment, "rounded corner" refers to the part of the rotor core 1 where the corners of each part are rounded. For example, in this embodiment, "rounded corner" refers to the part of the rotor core 1 where the corners of each part of the first punch hole 21, each part of the second punch hole 22, and each part of the third punch hole 23 are machined into an arc shape in a cross-section perpendicular to the rotation axis X of the rotor core 1.

[0018] As shown in Figures 1 and 2, multiple first cutouts 21 are formed within the region of the rotor core 1 sandwiched between a cylinder C1 and a cylinder C2, both centered on the rotation axis X. As shown in Figures 1 and 2, the multiple first cutouts 21 are arranged at equal intervals in the circumferential direction of a circle centered on a point on the rotation axis X, and their distance from the rotation axis X is constant.

[0019] The second cutout hole 22 has a cross-sectional shape defined by a plane perpendicular to the axis of rotation X, with three vertices of a figure enclosed by two line segments and a curve or line segment connecting points on those two line segments rounded. Specifically, the second cutout hole 22 has a cross-sectional shape defined by a plane perpendicular to the axis of rotation X, with three vertices of a figure enclosed by two line segments forming an interior angle A22 and a circular arc S22 centered on a point on the axis of rotation X rounded. Furthermore, the second cutout hole 22 is on a different plane from the plane of symmetry E of the first cutout hole 21, and is symmetrical with respect to the plane of symmetry F passing through the axis of rotation X. Moreover, the shape of the second cutout hole 22 is constant regardless of its position in the direction of the axis of rotation X.

[0020] As shown in Figures 1 and 2, multiple second cutouts 22 are formed within the region of the rotor core 1 between the cylinder C1 and the cylinder C3, both centered on the rotation axis X. The arc S22 of the second cutout 22 is located on cylinder C1. As shown in Figures 1 and 2, the multiple second cutouts 22 are arranged at equal intervals in the circumferential direction of a circle centered on a point on the rotation axis X, and their distance from the rotation axis X is constant. Furthermore, it is preferable that all second cutouts 22 are positioned at a distance equal to the distance from the two adjacent first cutouts 21 in the circumferential direction of a circle centered on a point on the rotation axis X. In addition, the point P22 on the arc of the second cutout 22 that is furthest from the rotation axis X is located further from the rotation axis X than the point P211 on the arc of the first cutout 21 that is closest to the rotation axis X.

[0021] The third cutout hole 23 has a cross-sectional shape defined by a plane perpendicular to the axis of rotation X, where the three vertices of a figure enclosed by two line segments and a curve or line segment connecting points on those two line segments are rounded. Specifically, the third cutout hole 23 has a cross-sectional shape defined by a plane perpendicular to the axis of rotation X, where the three vertices of a figure enclosed by two line segments forming an interior angle A23 and a circular arc S23 centered on a point on the axis of rotation X are rounded. Furthermore, the third cutout hole 23 is symmetrical with respect to the plane of symmetry F of the second cutout hole 22. Moreover, the shape of the third cutout hole 23 is constant regardless of its position in the direction of the axis of rotation X.

[0022] As shown in Figures 1 and 2, multiple third cutouts 23 are formed within the region of the rotor core 1 between the cylinder C2 and the cylinder C3, both centered on the rotation axis X. The arc S23 of the third cutout 23 is located on cylinder C2. As shown in Figures 1 and 2, the multiple third cutouts 23 are arranged at equal intervals in the circumferential direction of a circle centered on a point on the rotation axis X, and their distance from the rotation axis X is constant. Furthermore, it is preferable that all third cutouts 23 are located at positions equal to the distance from the two adjacent first cutouts 21 in the circumferential direction of a circle centered on a point on the rotation axis X. In addition, the point P23 closest to the rotation axis X among the points on the arc of the third cutout 23 is located closer to the rotation axis X than the point P212 furthest from the rotation axis X among the points on the arc of the first cutout 21. In a cross-section of a plane perpendicular to the rotation axis X, the area of ​​the third cutout 23 is smaller than the area of ​​the second cutout 22.

[0023] The first hole 21, the second hole 22, and the third hole 23 each receive and relieve the stress applied to the rotor core 1. The stress referred to here includes, for example, the stress generated by inserting the shaft into the rotor core 1, the stress generated by the centrifugal force of the rotor's rotation, and the stress generated by the rotor core 1 rotating relative to the shaft. For example, the inner angle A211 of the first hole 21 and the arc S22 of the second hole 22 receive and relieve the stress applied from inside the cylindrical part C1 of the rotor core 1.

[0024] Furthermore, since the rotor core 1 has a first hole 21, a second hole 22, and a third hole 23 formed therein, it includes the first bridge section B1, the second bridge section B2, and the third bridge section B3 shown in Figure 2.

[0025] The first bridge section B1 is the portion sandwiched between one side of the first hole 21 and one of the two line segments of the second hole 22 in a cross-section taken from a plane perpendicular to the axis of rotation X. The second bridge section B2 is the portion sandwiched between one side of the first hole 21 and one of the two line segments of the third hole 23 in a cross-section taken from a plane perpendicular to the axis of rotation X. The third bridge section B3 is the portion sandwiched between the interior angle A22 of the second hole 22 and the interior angle A23 of the third hole 23, and is connected to the two first bridge sections B1 and the two second bridge sections B2.

[0026] Furthermore, the first bridge section B1, the second bridge section B2, and the third bridge section B3 release the stress applied to the rotor core 1 from the inside to the outside of the rotor core 1. The stress referred to here includes, for example, the stress generated by inserting the shaft into the rotor core 1, the stress generated by the centrifugal force of the rotor's rotation, and the stress generated by the rotation of the rotor core 1 relative to the shaft.

[0027] For example, as shown by the white arrows in Figure 2, the rotor core 1 allows stress applied from inside the cylinder C1 to pass through the first bridge section B1, the third bridge section B3, and the second bridge section B2 in that order, releasing it to the outside of the cylinder C2. Alternatively, as shown by the dot-hatched arrows in Figure 2, the rotor core 1 allows stress applied from inside the cylinder C1 to pass through the first bridge section B1, the third bridge section B3, and the second bridge section B2 in that order, releasing it to the outside of the cylinder C2.

[0028] Therefore, it is preferable that the widths W1 of the first bridge section B1 and W2 of the second bridge section B2 satisfy the relationship 0.8 × W1 ≤ W2 ≤ W1 in order to avoid excessive stress concentration at specific locations in the rotor core 1. In other words, it is preferable that the rotor core 1 has a width W2 of the second bridge section B2 that is slightly narrower than the width W1 of the first bridge section B1, while suppressing the difference between the widths W1 of the first bridge section B1 and W2 of the second bridge section B2.

[0029] The rotor according to the embodiment has been described above. The rotor core 1 according to the embodiment includes a first cutout hole 21, a second cutout hole 22, and a third cutout hole 23. The first cutout hole 21 has a cross-sectional shape with a plane perpendicular to the rotation axis X of the rotor, with rounded corners at the four vertices of a rectangle, and is symmetrical with respect to the plane of symmetry E passing through the rotation axis X.

[0030] The second cutout hole 22 has a cross-sectional shape formed by a plane perpendicular to the axis of rotation X, where the three vertices of a figure enclosed by two line segments and a curve or line segment connecting points on those two segments are rounded. Furthermore, the second cutout hole 22 is on a different plane from the plane of symmetry E of the first cutout hole 21, and is symmetrical with respect to the plane of symmetry F passing through the axis of rotation X. Moreover, the point P22 on the rounded surface of the second cutout hole 22, which is furthest from the axis of rotation X, is located further from the axis of rotation X than the point P211 on the rounded surface of the first cutout hole 21, which is closest to the axis of rotation X.

[0031] The third cutout hole 23 has a cross-sectional shape defined by a plane perpendicular to the axis of rotation X. The three vertices of the figure enclosed by two line segments and a curve or line segment connecting points on those two line segments are rounded, and the shape is symmetrical with respect to the plane of symmetry F of the second cutout hole 22. Furthermore, the point P23 closest to the axis of rotation X among the points on the rounded surface of the third cutout hole 23 is located closer to the axis of rotation X than the point P212 furthest from the axis of rotation X among the points on the rounded surface of the first cutout hole 21.

[0032] As a result, the rotor core 1 can receive and relieve the stress applied to it at the first hole 21, the second hole 22, and the third hole 23. Furthermore, the rotor core 1 can release the stress from the inside to the outside through the space between two of the three holes, thereby relieving the stress. Therefore, the rotor core 1 can be prevented from fracturing due to this stress.

[0033] Furthermore, due to the positional relationship between points P22 and P211, and between points P23 and P212, the rotor core 1 is able to arrange the first hole 21, the second hole 22, and the third hole 23 within a narrow range in a direction perpendicular to the rotation axis X. As a result, the rotor core 1 can reduce the range in which its mechanical strength is reduced due to the arrangement of the first hole 21, the second hole 22, and the third hole 23. Consequently, the rotor core 1 can prevent the occurrence of fracture due to stress.

[0034] Furthermore, this allows the rotor core 1 to enjoy the benefits of forming the holes. Specifically, the rotor core 1 can concentrate magnetic flux at each pole, reducing eddy current losses. In addition, the rotor core 1 can reuse scraps of plate-shaped material to the extent that the first, second, and third holes 21, second holes 22, and third holes 23 are formed, thereby reducing the cost of manufacturing the motor. Moreover, the rotor core 1 can be made lighter to the extent that the first, second, and third holes 21, second holes 22, and third holes 23 are formed.

[0035] In the first hole 21, the interior angle A211 of the vertex closest to the axis of rotation X is greater than the interior angle A212 of the vertex furthest from the axis of rotation X. This allows the rotor core 1 to have a larger surface area in the first hole 21 that can receive and relieve stress applied from inside the cylinder C1 of the rotor core 1. Therefore, the rotor core 1 can more effectively receive and relieve stress applied from inside the cylinder C1 of the rotor core 1, thereby preventing fracture due to such stress.

[0036] The rotor core 1 comprises a first bridge section B1 and a second bridge section B2. The first bridge section B1 is the portion sandwiched between one side of the first hole 21 and one of the two line segments of the second hole 22 in a cross-section taken from a plane perpendicular to the rotation axis X. The second bridge section B2 is the portion sandwiched between one side of the first hole 21 and one of the two line segments of the third hole 23 in a cross-section taken from a plane perpendicular to the rotation axis X. Furthermore, the widths W1 of the first bridge section B1 and W2 of the second bridge section B2 satisfy the relation 0.8 × W1 ≤ W2 ≤ W1. In other words, the rotor core 1 suppresses the difference between the widths W1 of the first bridge section B1 and W2 of the second bridge section B2, while making the width W2 of the second bridge section B2 slightly narrower than the width W1 of the first bridge section B1.

[0037] This prevents stress from concentrating at specific points in the first bridge section B1 or the second bridge section B2 of the rotor core 1, thus preventing fracture. Furthermore, the stress applied to each part of the rotor core 1 decreases as it moves away from the rotation axis X. Therefore, the rotor core 1 can enjoy the benefits of forming a hole by narrowing the width W2 of the second bridge section B2 in accordance with this stress distribution.

[0038] The second hole 22 has a cross-sectional shape formed by a plane perpendicular to the axis of rotation X, with three vertices of the figure enclosed by two line segments and a circular arc A22 centered on a point on the axis of rotation X being rounded. As a result, the rotor core 1 can receive and relieve the stress generated by inserting the shaft into the rotor without concentrating it at a specific point in the second hole 22, instead distributing it across the entire circular arc A22 of the second hole 22.

[0039] In a cross-section defined by a plane perpendicular to the rotation axis X, the area of ​​the third hole 23 is smaller than the area of ​​the second hole 22. Furthermore, the stress applied to each part of the rotor core 1 decreases with increasing distance from the rotation axis X. In other words, the rotor core 1 is designed so that the areas of the second hole 22 and the third hole 23 are matched to this stress distribution. Therefore, the rotor core 1 can enjoy the benefits of forming the holes while simultaneously mitigating the stress applied to the rotor core 1.

[0040] In the embodiments described above, the example of a rotating electric machine being a motor was used, but the invention is not limited to this. The rotating electric machine in the embodiment may be a generator instead of a motor, for example.

[0041] Preferred embodiments of the present invention have been described above. However, the present invention is not limited to the embodiments described above. That is, the present invention includes embodiments that have been modified, substituted, or redesigned in accordance with the spirit of the present invention, and these embodiments are not excluded.

[0042] 1...Rotor core, 21...First hole, 22...Second hole, 23...Third hole

Claims

1. A first cutout whose cross-sectional shape, defined by a plane perpendicular to the rotor's axis of rotation, has rounded corners at the four vertices of a rectangle and is symmetrical with respect to a plane of symmetry passing through the axis of rotation; and a second cutout whose cross-sectional shape, defined by a plane perpendicular to the axis of rotation, has rounded corners at three vertices of a figure enclosed by two line segments and a curve or line segment connecting points on those two line segments, is on a different plane from the plane of symmetry of the first cutout, is symmetrical with respect to a plane of symmetry passing through the axis of rotation, and the point on the curve furthest from the axis of rotation is located further from the axis of rotation than the point on the curve of the first cutout that is closest to the axis of rotation. A rotor comprising: a rotor in which the cross-sectional shape of a plane perpendicular to the rotation axis is a figure enclosed by two line segments and a curve or line segment connecting two points on the two line segments, with three vertices of the figure having radii, the shape being symmetrical with respect to the plane of symmetry of the second hole, and the third hole having a point on the radii closest to the rotation axis that is closer to the rotation axis than the point on the radii of the first hole furthest from the rotation axis.

2. The rotor according to claim 1, wherein the second cutout has a cross-sectional shape formed by a plane perpendicular to the axis of rotation, and the three vertices of the figure are rounded, with the shape being enclosed by two line segments and an arc centered on a point on the axis of rotation.

3. The rotor according to claim 1, further comprising: a first bridge portion sandwiched between one side of the first cutout and one of the two line segments of the second cutout in a cross-section of a plane perpendicular to the axis of rotation; and a second bridge portion sandwiched between one side of the first cutout and one of the two line segments of the third cutout in a cross-section of a plane perpendicular to the axis of rotation, wherein the width W1 of the first bridge portion and the width W2 of the second bridge portion satisfy the relation 0.8 × W1 ≤ W2 ≤ W1.

4. The rotor according to claim 1, wherein the interior angle of the vertex closest to the axis of rotation in the first cutout is greater than the interior angle of the vertex furthest from the axis of rotation in the first cutout.

5. A rotating electric machine comprising a rotor according to any one of claims 1 to 4.

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