Rotor

Abstract

A rotor is provided. In the rotor, when viewed from the axial direction, a magnet is inserted into the side surface of the magnet insertion hole. A second straight line disposed so as to extend in a direction along the long side of the permanent magnet; a first arcuate portion connected to the first straight line and disposed between the first straight line and the second straight line; and a second arcuate portion connected to the second straight line and disposed between the first straight line and the second straight line. And an inter-arc linear portion connected to the first arc-shaped portion and to the second arc-shaped portion.

Description

Technical Field

[0001] The present invention relates to a rotor. Background Art

[0002] Conventionally, a rotor is known which includes a rotor core having a bridge portion provided adjacent to a magnet insertion hole. Such a rotor is disclosed, for example, in Japanese Unexamined Patent Application Publication No. 2021-136785.

[0003] In Japanese Unexamined Patent Application Publication No. 2021-136785, a rotor is disclosed which includes a rotor core having a magnet insertion hole (magnet insertion hole) in which a permanent magnet is disposed and a partition portion (bridge portion) provided adjacent to the magnet insertion hole. In the rotor described in Japanese Unexamined Patent Application Publication No. 2021-136785, the partition portion is provided such that the width is as small as possible within a range capable of ensuring the mechanical strength of the rotor core when viewed from the axial direction. Further, in the rotor described in Patent Document 1, a straight line (first straight line) forming the bridge portion, a straight line (second straight line) disposed so as to extend in a direction along the long side of the permanent magnet, and an arc-shaped portion connecting to the first straight line and connecting to the second straight line are provided on the side surface of the magnet insertion hole when viewed from the axial direction.

[0004] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2021-136785

[0005] Here, although not explicitly described in Japanese Patent Laid-Open No. 2021-136785, in an existing rotor as described in Japanese Patent Laid-Open No. 2021-136785, in order to prevent the connecting portions between the arc-shaped portion and the first straight line and between the arc-shaped portion and the second straight line from having sharp corners, it can be considered to connect the arc-shaped portion to the first straight line and the second straight line in such a way that the first straight line and the second straight line become tangents to the circle corresponding to the arc-shaped portion. In this case, as the radius of the circle corresponding to the arc-shaped portion varies within the tolerance range (the range of manufacturing errors), the positions of the connecting portion between the arc-shaped portion and the first straight line and the connecting portion between the arc-shaped portion and the second straight line change. That is, the position of the arc-shaped portion of the magnet insertion hole changes. In particular, when the included angle formed by the first straight line and the second straight line is relatively small, the position change of the arc-shaped portion is relatively large. Along with this, the shape (width or length) of the bridge portion formed by the first straight line connected to the arc-shaped portion changes. Moreover, in the rotor described in Japanese Patent Laid-Open No. 2021-136785, the bridge portion is set to have as small a width as possible within the range where the mechanical strength of the rotor core can be ensured when viewed from the axial direction. Therefore, if the shape of the bridge portion changes, the difference in mechanical strength between the rotor cores becomes larger. In addition, if the shape of the bridge portion changes, there may be magnetic flux leakage at the bridge portion. Therefore, a rotor is needed that can suppress the increase in the difference in mechanical strength between the rotor cores caused by the change in the shape of the bridge portion and the occurrence of magnetic flux leakage at the bridge portion. Summary of the Invention

[0006] The present invention has been completed to solve the above-described problems, and an object of the present invention is to provide a rotor that can suppress the increase in the difference in mechanical strength between rotor cores caused by the change in the shape of a bridge portion and the occurrence of magnetic flux leakage at the bridge portion.

[0007] To achieve the above object, a rotor according to one aspect of the present invention includes: a rotor core including magnet insertion holes and bridge portions provided adjacent to the magnet insertion holes; and permanent magnets disposed in the magnet insertion holes. When viewed from the axial direction, on the side surface of the magnet insertion hole, a first straight line forming the bridge portion, a second straight line arranged to extend in a direction along the long side of the permanent magnet, a first arc-shaped portion connected to the first straight line and disposed between the first straight line and the second straight line, a second arc-shaped portion connected to the second straight line and disposed between the first straight line and the second straight line are provided, and an inter-arc straight line portion connected to the first arc-shaped portion and the second arc-shaped portion or an inter-arc curved line portion having a curvature smaller than that of the first arc-shaped portion and the second arc-shaped portion is provided. In addition, in the specification of the present application, the so-called "direction along the long side of the permanent magnet" is a broad concept including both the long side direction of the permanent magnet itself and a direction relatively close to the long side direction of the permanent magnet.

[0008] In the rotor according to one aspect of the present invention, as described above, when viewed axially, on the side surface of the magnet insertion hole, a first straight line forming a bridge portion, a second straight line arranged so as to extend in the direction along the long side of the permanent magnet, a first arc-shaped portion connected to the first straight line and arranged between the first straight line and the second straight line, a second arc-shaped portion connected to the second straight line and arranged between the first straight line and the second straight line are provided, and an inter-arc straight portion connected to the first arc-shaped portion and connected to the second arc-shaped portion or an inter-arc curved portion having a curvature smaller than that of the first arc-shaped portion and the second arc-shaped portion is provided. Thus, two arc-shaped portions can be formed between the first straight line and the second straight line on the side surface of the magnet insertion hole, namely, a first arc-shaped portion connected to the first straight line and connected to the inter-arc straight portion or the inter-arc curved portion, and a second arc-shaped portion connected to the second straight line and connected to the inter-arc straight portion or the inter-arc curved portion. In this case, since the tangent at the connection portion between the inter-arc straight portion and the first arc-shaped portion or the connection portion between the inter-arc curved portion and the first arc-shaped portion and the tangent at the connection portion between the inter-arc curved portion and the second arc-shaped portion extend in a direction intersecting the first straight line and the second straight line, the angle formed by the tangent at the connection portion between the inter-arc straight portion and the first arc-shaped portion or the connection portion between the inter-arc curved portion and the first arc-shaped portion and the first straight line, and the angle formed by the tangent at the connection portion between the inter-arc straight portion and the second arc-shaped portion or the connection portion between the inter-arc curved portion and the second arc-shaped portion and the second straight line are larger than the angle formed by the first straight line and the second straight line. Here, the absolute value of the angle formed by the straight line connected to one end of the arc-shaped portion and the straight line connected to the other end of the arc-shaped portion, or the angle formed by the straight line connected to one end of the arc-shaped portion and the tangent at the connection portion between the arc-shaped portion and the curve connected to the other end of the arc-shaped portion and having a curvature smaller than that of the arc-shaped portion is closer to 0 degrees (smaller), the larger the amount of position change of the arc-shaped portion in the protruding direction of the arc-shaped portion caused by the change of the radius of the circle corresponding to the arc-shaped portion within the tolerance range (the range of manufacturing error). Therefore, compared with the case where only one arc-shaped portion is provided between the first straight line and the second straight line on the side surface of the magnet insertion hole, the amount of shape change of the bridge portion formed by the first straight line due to the change of the radius of the circle corresponding to the arc-shaped portion within the tolerance range can be reduced. As a result, it is possible to suppress the increase in the difference in mechanical strength between the rotor cores caused by the change in the shape of the bridge portion and the occurrence of magnetic flux leakage at the bridge portion.

[0009] In the rotor according to the above aspect, it is preferable that the angle formed by the first straight line and the second straight line is an acute angle.

[0010] With such a configuration, in the case where the included angle formed by the first straight line and the second straight line is a relatively small acute angle and only one arc-shaped portion is provided between the first straight line and the second straight line on the side surface of the magnet insertion hole, the shape change amount formed by the bridge portion formed by the first straight line accompanying the change of the radius of the circle corresponding to the arc-shaped portion within the tolerance range is relatively large. Therefore, it is possible to effectively reduce the shape change amount formed by the bridge portion formed by the first straight line accompanying the change of the radius of the circle corresponding to the arc-shaped portion within the tolerance range (the range of manufacturing errors).

[0011] In the rotor of the above-mentioned one aspect, it is preferable that the included angle formed by the tangent line at the connecting portion between the straight line portion between the arcs and the first arc-shaped portion or at the connecting portion between the curved line portion between the arcs and the first arc-shaped portion and the first straight line, and the included angle formed by the tangent line at the connecting portion between the straight line portion between the arcs and the second arc-shaped portion or at the connecting portion between the curved line portion between the arcs and the second arc-shaped portion and the second straight line are obtuse angles.

[0012] With such a configuration, since the included angle formed by the tangent line at the connecting portion between the straight line portion between the arcs and the first arc-shaped portion or at the connecting portion between the curved line portion between the arcs and the first arc-shaped portion and the first straight line, and the included angle formed by the tangent line at the connecting portion between the straight line portion between the arcs and the second arc-shaped portion and the second straight line are relatively large obtuse angles, it is possible to sufficiently reduce the change amount formed by the shape of the bridge portion formed by the first straight line accompanying the change of the radius of the circle corresponding to the arc-shaped portion within the tolerance range (the range of manufacturing errors).

[0013] In the rotor of the above-mentioned one aspect, it is preferable that the first straight line is arranged adjacent to the void portion in the magnet insertion hole where no permanent magnet is arranged.

[0014] With such a configuration, for the bridge portion formed by the first straight line, since it is arranged adjacent to the void portion in the magnet insertion hole, the influence of the shape change on the mechanical strength of the rotor core is particularly large. Therefore, it is possible to effectively reduce the change amount formed by the shape of the bridge portion formed by the first straight line accompanying the change of the radius of the circle corresponding to the arc-shaped portion within the tolerance range (the range of manufacturing errors).

[0015] In the rotor of the above-mentioned one aspect, it is preferable that the first straight line is arranged to form a bridge portion located between adjacent magnet insertion holes arranged in a V shape.

[0016] With such a configuration, since the included angle formed by the second straight line and the first straight line forming the bridge portion located between adjacent magnet insertion holes arranged in a V shape is a relatively small acute angle, it is possible to effectively reduce the change amount formed by the shape of the bridge portion formed by the first straight line accompanying the change of the radius of the circle corresponding to the arc-shaped portion within the tolerance range (manufacturing errors) change. Brief Description of the Drawings

[0017] Figure 1 It is a top view showing the rotor in the first embodiment of the present invention.

[0018] Figure 2 It is a top view showing the first straight line, the second straight line, the first arc-shaped portion, the second arc-shaped portion, and the straight line portion between the arcs at the magnet insertion hole and the notch of the rotor in the first embodiment of the present invention.

[0019] Figure 3 It is a diagram for explaining the change in position formed by the change in the radius of the circle corresponding to the arc-shaped portion within the tolerance range of the arc-shaped portion.

[0020] Figure 4 It is a top view showing the first straight line, the second straight line, the first arc-shaped portion, the second arc-shaped portion, and the curved line portion between the arcs at the magnet insertion hole and the notch of the rotor in the second embodiment of the present invention.

[0021] Figure 5 It is a top view showing the first straight line, the second straight line, the first arc-shaped portion, the second arc-shaped portion, and the straight line portion between the arcs at the magnet insertion hole and the notch of the rotor in the comparative example. Detailed Description of the Invention

[0022] Hereinafter, embodiments of the present invention will be described based on the drawings.

[0023] [First Embodiment]

[0024] Refer to Figure 1 and Figure 2 to describe the structure of the rotor 100 in the first embodiment of the present invention.

[0025] In the following description, the axial direction, the radial direction, and the circumferential direction of the rotor 100 (refer to Figure 1 ) are set as the Z direction, the R direction, and the C direction, respectively. In addition, the inner side and the outer side of the rotor 100 in the radial direction (R direction) are set as the R1 side and the R2 side, respectively. In addition, one side and the other side of the rotor 100 in the circumferential direction (C direction) are set as the C1 side and the C2 side, respectively.

[0026] (Overall Structure of the Rotor)

[0027] As Figure 1 shown, the rotor 100 is formed in an annular shape. The rotor 100 and a stator (not shown) disposed opposite to the rotor 100 on the R2 side of the rotor 100 together constitute a part of an inner rotor type rotating electric machine (not shown). The rotating electric machine is, for example, a motor, a generator, or a motor-generator.

[0028] The rotor 100 includes a rotor core 1. The rotor core 1 is formed by laminating a plurality of electromagnetic steel sheets (such as silicon steel sheets) in the Z direction.

[0029] <Structure of magnet insertion holes>

[0030] The rotor core 1 includes magnet insertion holes 10. The magnet insertion holes 10 penetrate the rotor core 1 in the Z direction. A plurality of magnet insertion holes 10 are provided in a portion of the rotor core 1 on the R2 side.

[0031] The magnet insertion holes 10 include a first magnet insertion hole 11, a second magnet insertion hole 12, a third magnet insertion hole 13, a fourth magnet insertion hole 14, a fifth magnet insertion hole 15, and a sixth magnet insertion hole 16. One set of the first magnet insertion hole 11, the second magnet insertion hole 12, the third magnet insertion hole 13, the fourth magnet insertion hole 14, the fifth magnet insertion hole 15, and the sixth magnet insertion hole 16 corresponds to one magnetic pole in the rotor core 1.

[0032] The first magnet insertion hole 11 is arranged such that on the C1 side of the q-axis, the long side direction of the first magnet insertion hole 11 extends along the R direction.

[0033] The second magnet insertion hole 12 is arranged such that on the C2 side of the q-axis, the long side direction of the second magnet insertion hole 12 extends along the R direction.

[0034] The third magnet insertion hole 13 is arranged to extend along the C direction on the d-axis side of the first magnet insertion hole 11. The end on the C1 side of the third magnet insertion hole 13 is arranged near the d-axis. The end on the C2 side of the third magnet insertion hole 13 is arranged near the end on the R1 side of the first magnet insertion hole 11. That is, the first magnet insertion hole 11 and the third magnet insertion hole 13 are arranged in a V shape.

[0035] The fourth magnet insertion hole 14 is arranged to extend along the C direction on the d-axis side of the second magnet insertion hole 12. The end on the C2 side of the fourth magnet insertion hole 14 is arranged near the d-axis and is arranged to face the end on the C1 side of the third magnet insertion hole 13. The end on the C1 side of the fourth magnet insertion hole 14 is arranged near the end on the R1 side of the second magnet insertion hole 12. That is, the second magnet insertion hole 12 and the fourth magnet insertion hole 14 are arranged in a V shape.

[0036] The fifth magnet insertion hole 15 is arranged on the R2 side of the third magnet insertion hole 13. The fifth magnet insertion hole 15 is arranged to extend along the C direction on the C2 side of the d-axis. The end on the C1 side of the fifth magnet insertion hole 15 is arranged near the d-axis.

[0037] The sixth magnet insertion hole 16 is disposed on the R2 side of the fourth magnet insertion hole 14. The sixth magnet insertion hole 16 is disposed to extend in the C direction on the C1 side of the d-axis. The end portion of the sixth magnet insertion hole 16 on the C2 side is disposed near the d-axis and is disposed so as to face the end portion of the fifth magnet insertion hole 15 on the C1 side.

[0038] <Structure of the notch>

[0039] The rotor core 1 includes a notch 20. The notch 20 penetrates the rotor core 1 in the Z direction. The notch 20 is formed in the outer peripheral portion 1a of the rotor core 1. The notch 20 is formed in the R direction.

[0040] The notch 20 includes a first notch 21 and a second notch 22.

[0041] The end portion of the first notch 21 on the R1 side is disposed near the end portion of the fifth magnet insertion hole 15 on the C2 side. That is, the first notch 21 and the fifth magnet insertion hole 15 are disposed in a V shape.

[0042] The end portion of the second notch 22 on the R1 side is disposed near the end portion of the sixth magnet insertion hole 16 on the C1 side. That is, the second notch 22 and the sixth magnet insertion hole 16 are disposed in a V shape.

[0043] <Structure of the bridge portion>

[0044] The rotor core 1 includes a bridge portion 30. The bridge portion 30 is provided adjacent to the magnet insertion hole 10. The bridge portion 30 is formed to have a relatively small width within a range that can ensure the mechanical strength of the rotor core 1 when viewed from the Z direction.

[0045] The bridge portion 30 includes a first bridge portion 31, a second bridge portion 32, a third bridge portion 33, a fourth bridge portion 34, a fifth bridge portion 35, a sixth bridge portion 36, a seventh bridge portion 37, and an eighth bridge portion 38.

[0046] The first bridge portion 31 is disposed between the end portion of the first magnet insertion hole 11 on the R2 side and the outer peripheral surface of the rotor core 1.

[0047] The second bridge portion 32 is disposed between the end portion of the first magnet insertion hole 11 on the R1 side and the end portion of the third magnet insertion hole 13 on the C2 side. That is, the second bridge portion 32 is located between the adjacent first magnet insertion hole 11 and the third magnet insertion hole 13 disposed in a V shape.

[0048] The third bridge portion 33 is disposed between the end portion of the second magnet insertion hole 12 on the R2 side and the outer peripheral surface of the rotor core 1.

[0049] The fourth bridge portion 34 is provided between the end portion of the second magnet insertion hole 12 on the R1 side and the end portion of the fourth magnet insertion hole 14 on the C1 side. That is, the fourth bridge portion 34 is located between the adjacent second magnet insertion hole 12 and fourth magnet insertion hole 14 arranged in a V shape.

[0050] The fifth bridge portion 35 is provided between the end portion of the third magnet insertion hole 13 on the C1 side and the end portion of the fourth magnet insertion hole 14 on the C2 side.

[0051] The sixth bridge portion 36 is provided between the end portion of the fifth magnet insertion hole 15 on the C1 side and the end portion of the sixth magnet insertion hole 16 on the C2 side.

[0052] The seventh bridge portion 37 is provided between the end portion of the fifth magnet insertion hole 15 on the C2 side and the end portion of the first notch 21 on the R1 side. That is, the seventh bridge portion 37 is located between the adjacent fifth magnet insertion hole 15 and first notch 21 arranged in a V shape. In other words, the first notch 21 is formed in such a way as to clamp the seventh bridge portion 37 between it and the fifth magnet insertion hole 15.

[0053] The eighth bridge portion 38 is provided between the end portion of the sixth magnet insertion hole 16 on the C1 side and the end portion of the second notch 22 on the R1 side. That is, the eighth bridge portion 38 is located between the adjacent sixth magnet insertion hole 16 and second notch 22 arranged in a V shape. In other words, the second notch 22 is formed in such a way as to clamp the eighth bridge portion 38 between it and the sixth magnet insertion hole 16.

[0054] <Structure of permanent magnet>

[0055] The rotor 100 is provided with permanent magnets 2. When observed from the Z direction, the permanent magnets 2 have a rectangular shape. The permanent magnets 2 are arranged one by one in each magnet insertion hole 10. The permanent magnets 2 are, for example, neodymium magnets. In addition, a gap portion 10a is formed in the portion of the magnet insertion hole 10 where no permanent magnet 2 is arranged (refer to Figure 2 ).

[0056] (Details of magnet insertion hole)

[0057] <Fourth magnet insertion hole>

[0058] As Figure 2As shown, when viewed from the Z direction, on the side surface of the fourth magnet insertion hole 14, there are provided a first straight line L4a forming the fourth bridge portion 34, a second straight line L4b arranged to extend in the direction along the long side of the permanent magnet 2, a first arc-shaped portion L4c connected to the first straight line L4a and arranged between the first straight line L4a and the second straight line L4b, a second arc-shaped portion L4d connected to the second straight line L4b and arranged between the first straight line L4a and the second straight line L4b, and an inter-arc straight line portion L4e connected to the first arc-shaped portion L4c and connected to the second arc-shaped portion L4d. That is, on the side surface of the fourth magnet insertion hole 14, the first straight line L4a, the first arc-shaped portion L4c, the inter-arc straight line portion L4e, the second arc-shaped portion L4d, and the second straight line L4b are sequentially connected.

[0059] In order to prevent the connecting portion between the first straight line L4a and the first arc-shaped portion L4c from having sharp corners, the first arc-shaped portion L4c is connected to the first straight line L4a in such a way that the first straight line L4a becomes the tangent of the first arc-shaped portion L4c. That is, the first straight line L4a and the first arc-shaped portion L4c are smoothly connected. In addition, in order to prevent the connecting portion between the inter-arc straight line portion L4e and the first arc-shaped portion L4c from having sharp corners, the first arc-shaped portion L4c is connected to the inter-arc straight line portion L4e in such a way that the inter-arc straight line portion L4e becomes the tangent of the first arc-shaped portion L4c. That is, the inter-arc straight line portion L4e and the first arc-shaped portion L4c are smoothly connected. In addition, in order to prevent the connecting portion between the inter-arc straight line portion L4e and the second arc-shaped portion L4d from having sharp corners, the second arc-shaped portion L4d is connected to the inter-arc straight line portion L4e in such a way that the inter-arc straight line portion L4e becomes the tangent of the second arc-shaped portion L4d. That is, the inter-arc straight line portion L4e and the second arc-shaped portion L4d are smoothly connected. In addition, in order to prevent the connecting portion between the second straight line L4b and the second arc-shaped portion L4d from having sharp corners, the second arc-shaped portion L4d is connected to the second straight line L4b in such a way that the second straight line L4b becomes the tangent of the second arc-shaped portion L4d. That is, the second straight line L4b and the second arc-shaped portion L4d are smoothly connected.

[0060] The included angle A41 formed by the first straight line L4a and the second straight line L4b is an acute angle. That is, the first arc-shaped portion L4c, the second arc-shaped portion L4d, and the inter-arc straight line portion L4e are arranged between the first straight line L4a and the second straight line L4b forming the angle A41.

[0061] The included angle A42 formed by the first straight line L4a and the straight-line portion L4e between the arcs is an obtuse angle. That is, the straight-line portion L4e between the arcs is arranged such that the included angle A42 formed by it and the first straight line L4a becomes an obtuse angle. In addition, the included angle A43 formed by the second straight line L4b and the straight-line portion L4e between the arcs is an obtuse angle. That is, the straight-line portion L4e between the arcs is arranged such that the included angle A43 formed by it and the second straight line L4b becomes an obtuse angle.

[0062] The first straight line L4a is arranged adjacent to the gap portion 10a in the 4th magnet insertion hole 14 where the permanent magnet 2 is not arranged. In addition, the first straight line L4a is arranged to form the 4th bridge portion 34 located between the adjacent 4th magnet insertion hole 14 and the 2nd magnet insertion hole 12 arranged in a V shape.

[0063] <6th Magnet Insertion Hole>

[0064] When viewed from the Z direction, on the side surface of the 6th magnet insertion hole 16, there are provided a first straight line L6a forming the 8th bridge portion 38, a second straight line L6b arranged to extend in the direction along the long side of the permanent magnet 2, a first arc-shaped portion L6c connected to the first straight line L6a and arranged between the first straight line L6a and the second straight line L6b, a second arc-shaped portion L6d connected to the second straight line L6b and arranged between the first straight line L6a and the second straight line L6b, and an arc-intermediate straight-line portion L6e connected to the first arc-shaped portion L6c and connected to the second arc-shaped portion L6d. That is, on the side surface of the 6th magnet insertion hole 16, the first straight line L6a, the first arc-shaped portion L6c, the arc-intermediate straight-line portion L6e, the second arc-shaped portion L6d, and the second straight line L6b are sequentially connected.

[0065] In order to prevent the connecting part between the first straight line L6a and the first arc-shaped part L6c from having sharp corners, the first arc-shaped part L6c is connected to the first straight line L6a in such a way that the first straight line L6a becomes the tangent of the first arc-shaped part L6c. That is, the first straight line L6a and the first arc-shaped part L6c are smoothly connected. In addition, in order to prevent the connecting part between the straight line part L6e between arcs and the first arc-shaped part L6c from having sharp corners, the first arc-shaped part L6c is connected to the straight line part L6e between arcs in such a way that the straight line part L6e between arcs becomes the tangent of the first arc-shaped part L6c. That is, the straight line part L6e between arcs and the first arc-shaped part L6c are smoothly connected. In addition, in order to prevent the connecting part between the straight line part L6e between arcs and the second arc-shaped part L6d from having sharp corners, the second arc-shaped part L6d is connected to the straight line part L6e between arcs in such a way that the straight line part L6e between arcs becomes the tangent of the second arc-shaped part L6d. That is, the straight line part L6e between arcs and the second arc-shaped part L6d are smoothly connected. In addition, in order to prevent the connecting part between the second straight line L6b and the second arc-shaped part L6d from having sharp corners, the second arc-shaped part L6d is connected to the second straight line L6b in such a way that the second straight line L6b becomes the tangent of the second arc-shaped part L6d. That is, the second straight line L6b and the second arc-shaped part L6d are smoothly connected.

[0066] The included angle A61 formed by the first straight line L6a and the second straight line L6b is an acute angle. That is, the first arc-shaped part L6c, the second arc-shaped part L6d, and the straight line part L6e between arcs are arranged between the first straight line L6a and the second straight line L6b forming the angle A61.

[0067] The included angle A62 formed by the first straight line L6a and the straight line part L6e between arcs is an obtuse angle. That is, the straight line part L6e between arcs is arranged such that the included angle A62 formed by it and the first straight line L6a becomes an obtuse angle. In addition, the included angle A63 formed by the second straight line L6b and the straight line part L6e between arcs is an obtuse angle. That is, the straight line part L6e between arcs is arranged such that the included angle A63 formed by it and the second straight line L6b becomes an obtuse angle.

[0068] The first straight line L6a is arranged so as to be adjacent to the gap part 10a in the 6th magnet insertion hole 16 where no permanent magnet 2 is arranged. In addition, the first straight line L6a is arranged so as to form the 8th bridge part 38 located between the adjacent 6th magnet insertion hole 16 and the 2nd notch 22 arranged in a V shape.

[0069] (Details of the notch)

[0070] When viewed from the Z direction, at the side surface of the second notch 22, there are provided a first straight line L2a forming an eighth bridge portion 38, a second straight line L2b arranged to face the first straight line L2a in the second notch 22, a first arc-shaped portion L2c connected to the first straight line L2a and arranged between the first straight line L2a and the second straight line L2b, a second arc-shaped portion L2d connected to the second straight line L2b and arranged between the first straight line L2a and the second straight line L2b, and an inter-arc straight portion L2e connected to the first arc-shaped portion L2c and connected to the second arc-shaped portion L2d. That is, at the side surface of the second notch 22, the first straight line L2a, the first arc-shaped portion L2c, the inter-arc straight portion L2e, the second arc-shaped portion L2d, and the second straight line L2b are sequentially connected.

[0071] In order to prevent the connecting portion between the first straight line L2a and the first arc-shaped portion L2c from having sharp corners, the first arc-shaped portion L2c is connected to the first straight line L2a such that the first straight line L2a becomes a tangent line of the first arc-shaped portion L2c. That is, the first straight line L2a and the first arc-shaped portion L2c are smoothly connected. In addition, in order to prevent the connecting portion between the inter-arc straight portion L2e and the first arc-shaped portion L2c from having sharp corners, the first arc-shaped portion L2c is connected to the inter-arc straight portion L2e such that the inter-arc straight portion L2e becomes a tangent line of the first arc-shaped portion L2c. That is, the inter-arc straight portion L2e and the first arc-shaped portion L2c are smoothly connected. In addition, in order to prevent the connecting portion between the inter-arc straight portion L2e and the second arc-shaped portion L2d from having sharp corners, the second arc-shaped portion L2d is connected to the inter-arc straight portion L2e such that the inter-arc straight portion L2e becomes a tangent line of the second arc-shaped portion L2d. That is, the inter-arc straight portion L2e and the second arc-shaped portion L2d are smoothly connected. In addition, in order to prevent the connecting portion between the second straight line L2b and the second arc-shaped portion L2d from having sharp corners, the second arc-shaped portion L2d is connected to the second straight line L2b such that the second straight line L2b becomes a tangent line of the second arc-shaped portion L2d. That is, the second straight line L2b and the second arc-shaped portion L2d are smoothly connected.

[0072] The included angle A21 formed by the first straight line L2a and the second straight line L2b is an acute angle. That is, the first arc-shaped portion L2c, the second arc-shaped portion L2d, and the inter-arc straight portion L2e are arranged between the first straight line L2a and the second straight line L2b forming the angle A21.

[0073] The included angle A22 formed by the first straight line L2a and the straight-line portion L2e between the arcs is an obtuse angle. That is, the straight-line portion L2e between the arcs is arranged such that the included angle A22 formed with the first straight line L2a is an obtuse angle. Further, the included angle A23 formed by the second straight line L2b and the straight-line portion L2e between the arcs is an obtuse angle. That is, the straight-line portion L2e between the arcs is arranged such that the included angle A23 formed with the second straight line L2b is an obtuse angle.

[0074] The first straight line L2a is provided in such a manner as to form an eighth bridge portion 38 located between the adjacent second notches 22 and the sixth magnet insertion holes 16 arranged in a V shape.

[0075] (Change in the position of the arc-shaped portion due to a change in the radius of the circle corresponding to the arc-shaped portion within the tolerance range)

[0076] Refer to Figure 2 、 Figure 3 and Figure 5 A description will be given of the change in the position of the arc-shaped portion CA due to a change in the radius R of the circle corresponding to the arc-shaped portion CA within the tolerance range ΔR (range of manufacturing error).

[0077] As Figure 3 shown, consider the case where the arc-shaped portion CA is connected to the straight lines L1a and L1b such that the straight lines L1a and L1b are tangents to the circle corresponding to the arc-shaped portion CA, and consider the case where the radius R of the circle corresponding to the arc-shaped portion CA changes within the tolerance range ΔR (range of manufacturing error).

[0078] In this case, when the radius R of the circle is the minimum value R of the tolerance range ΔR (range of manufacturing error), the connection portion CP S where the arc-shaped portion CA S is connected to the straight line L1a S and the position of the connection portion CP L where the arc-shaped portion CA L is connected to the straight line L1a when the radius R of the circle is the maximum value R of the tolerance range ΔR L change by ΔX along the extending direction of the straight line L1a. Similarly, when the radius R of the circle is the minimum value R of the tolerance range ΔR S the connection portion CP S where the arc-shaped portion CA S is connected to the straight line L1b L and the position of the connection portion CP L where the arc-shaped portion CA LThe position changes by ΔX along the direction in which the straight line L1b extends. That is, as the radius R of the circle corresponding to the arc-shaped portion CA changes within the tolerance range ΔR (the minimum value R S ~the maximum value R L ), the position of the arc-shaped portion CA changes by ΔC in the direction in which the arc-shaped portion CA protrudes. In addition, ΔC = ΔX / cos(θ / 2) - ΔR.

[0079] Furthermore, when the straight line L1a and the straight line L1b form an angle θ, ΔX = ΔR / tan(θ / 2) holds. According to the above relational expression, within the range where the angle θ is greater than 0 degrees and less than 180 degrees, the larger the angle θ, the smaller ΔX. That is, for the amount of position change ΔC of the arc-shaped portion CA in the direction in which the arc-shaped portion CA protrudes, which is formed as the radius R of the circle corresponding to the arc-shaped portion CA changes within the tolerance range ΔR (the range of manufacturing errors), the amount of change ΔC when the angle θ is an obtuse angle is smaller than the amount of change ΔC when the angle θ is an acute angle.

[0080] Therefore, as Figure 2 shown, in the structure where the first arc-shaped portion L4c, the second arc-shaped portion L4d, and the straight line portion L4e between the arcs are provided between the first straight line L4a and the second straight line L4b, the included angle A42 formed by the first straight line L4a and the straight line portion L4e between the arcs is an obtuse angle. Therefore, the amount of position change of the first arc-shaped portion L4c that changes as the radius R of the circle corresponding to the first arc-shaped portion L4c changes within the tolerance range ΔR (the range of manufacturing errors) is relatively small. In addition, since the included angle A43 formed by the second straight line L4b and the straight line portion L4e between the arcs is an obtuse angle, the amount of position change of the second arc-shaped portion L4d that changes as the radius R of the circle corresponding to the second arc-shaped portion L4d changes within the tolerance range ΔR is relatively small. In addition, in Figure 2 , the first arc-shaped portion L4c when the radius R of the circle corresponding to the first arc-shaped portion L4c is the minimum value R S of the tolerance range ΔR, and the second arc-shaped portion L4d when the radius R of the circle corresponding to the second arc-shaped portion L4d is the minimum value R S of the tolerance range ΔR are represented by solid lines, and the first arc-shaped portion L4c when the radius R of the circle corresponding to the first arc-shaped portion L4c is the maximum value R L of the tolerance range ΔR, and the second arc-shaped portion L4d when the radius R of the circle corresponding to the second arc-shaped portion L4d is the maximum value R LThe second arcuate portion L4d at [a certain time] is represented by a dashed line. In addition, the content related to the amount of position change of the above-mentioned arcuate portion in the structure where the first arcuate portion L4c, the second arcuate portion L4d, and the straight line portion L4e between the arcs are provided between the first straight line L4a and the second straight line L4b is the same in the structure where the first arcuate portion L6c, the second arcuate portion L6d, and the straight line portion L6e between the arcs are provided between the first straight line L6a and the second straight line L6b, and in the structure where the first arcuate portion L2c, the second arcuate portion L2d, and the straight line portion L2e between the arcs are provided between the first straight line L2a and the second straight line L2b.

[0081] On the other hand, as shown in the comparative example of Figure 5 , between the first straight line L4a and the second straight line L4b, the first arcuate portion L4c, the second arcuate portion L4d, and the straight line portion L4e between the arcs are not provided, and only one arcuate portion C4a is provided. In this structure, the included angle A41 formed by the first straight line L4a and the second straight line L4b is an acute angle. Therefore, the amount of position change of the arcuate portion C4a that changes as the radius R of the circle corresponding to the arcuate portion C4a changes within the tolerance range ΔR (the range of manufacturing error) is relatively large. In addition, in Figure 4 , the arcuate portion C4a when the radius R of the circle corresponding to the arcuate portion C4a is the minimum value R S of the tolerance range ΔR is represented by a solid line, and the arcuate portion C4a when the radius R of the circle corresponding to the arcuate portion C4a is the maximum value R L of the tolerance range ΔR is represented by a dashed line. In addition, the content related to the amount of position change of the above-mentioned arcuate portion in the structure where only one arcuate portion C4a is provided between the first straight line L4a and the second straight line L4b is the same in the structure where only one arcuate portion is provided between the first straight line L6a and the second straight line L6b, and in the structure where only one arcuate portion is provided between the first straight line L2a and the second straight line L2b.

[0082] [Effects of the First Embodiment]

[0083] In the first embodiment, the following effects can be obtained.

[0084] In the first embodiment, as described above, when viewed from the Z direction, on the side surface of the fourth magnet insertion hole 14, there are provided a first straight line L4a forming the fourth bridge portion 34, a second straight line L4b arranged so as to extend in the direction along the long side of the permanent magnet 2, a first arc-shaped portion L4c connected to the first straight line L4a and arranged between the first straight line L4a and the second straight line L4b, a second arc-shaped portion L4d connected to the second straight line L4b and arranged between the first straight line L4a and the second straight line L4b, and an inter-arc straight line portion L4e connected to the first arc-shaped portion L4c and connected to the second arc-shaped portion L4d. Thus, in the side surface of the fourth magnet insertion hole 14, two arc-shaped portions can be formed between the first straight line L4a and the second straight line L4b, namely, the first arc-shaped portion L4c connected to the first straight line L4a and connected to the inter-arc straight line portion L4e, and the second arc-shaped portion L4d connected to the second straight line L4b and connected to the inter-arc straight line portion L4e. In this case, since the inter-arc straight line portion L4e extends in a direction intersecting the first straight line L4a and the second straight line L4b, the included angle A42 formed by the first straight line L4a and the inter-arc straight line portion L4e, and the included angle A43 formed by the second straight line L4b and the inter-arc straight line portion L4e are larger than the included angle A41 formed by the first straight line L4a and the second straight line L4b. Here, the closer the absolute value of the included angle θ formed by the straight line connected to one end of the arc-shaped portion CA and the straight line connected to the other end of the arc-shaped portion is to 0 degrees (the smaller), the larger the position change amount ΔC of the arc-shaped portion CA in the protruding direction of the arc-shaped portion CA formed as the radius R of the circle corresponding to the arc-shaped portion CA changes within the tolerance range ΔR (the range of manufacturing error). Therefore, compared with the case where only one arc-shaped portion is provided between the first straight line L4a and the second straight line L4b on the side surface of the fourth magnet insertion hole 14, the shape change amount formed as the radius R of the circle corresponding to the first arc-shaped portion L4c and the radius R of the circle corresponding to the second arc-shaped portion L4d each change within the tolerance range ΔR of the fourth bridge portion 34 formed by the first straight line L4a can be reduced. As a result, it is possible to suppress the increase in the difference in mechanical strength between the rotor cores 1 caused by the change in the shape of the fourth bridge portion 34 and the occurrence of magnetic flux leakage at the fourth bridge portion 34. In addition, the same effect as that of the above-described fourth magnet insertion hole 14 can also be obtained at the sixth magnet insertion hole 16 and the second notch 22.

[0085] In addition, in the first embodiment, as described above, the included angle A41 formed by the first straight line L4a and the second straight line L4b is an acute angle. Thus, in a case where only one arc-shaped portion is provided between the first straight line L4a and the second straight line L4b on the side surface of the fourth magnet insertion hole 14 because the included angle A41 formed by the first straight line L4a and the second straight line L4b is a relatively small acute angle, the amount of shape change formed by the change of the radius R of the circle corresponding to the first arc-shaped portion L4c and the radius R of the circle corresponding to the second arc-shaped portion L4d within the tolerance range ΔR for each of the fourth bridge portions 34 formed by the first straight line L4a is relatively large. Therefore, it is possible to effectively reduce the amount of shape change formed by the change of the radius R of the circle corresponding to the first arc-shaped portion L4c and the radius R of the circle corresponding to the second arc-shaped portion L4d within the tolerance range ΔR (range of manufacturing errors) for each of the fourth bridge portions 34 formed by the first straight line L4a. In addition, at the sixth magnet insertion hole 16 and the second notch 22, the same effects as those of the above-described fourth magnet insertion hole 14 can also be obtained.

[0086] In addition, in the first embodiment, as described above, the included angle A42 formed by the first straight line L4a and the straight line portion L4e between the arcs is an obtuse angle. In addition, the included angle A43 formed by the second straight line L4b and the straight line portion L4e between the arcs is an obtuse angle. Thus, since the included angle A42 formed by the first straight line L4a and the straight line portion L4e between the arcs and the included angle A43 formed by the second straight line L4b and the straight line portion L4e between the arcs are relatively large obtuse angles, it is possible to sufficiently reduce the amount of shape change formed by the change of the radius R of the circle corresponding to the first arc-shaped portion L4c and the radius R of the circle corresponding to the second arc-shaped portion L4d within the tolerance range ΔR (range of manufacturing errors) for each of the fourth bridge portions 34 formed by the first straight line L4a. In addition, at the sixth magnet insertion hole 16 and the second notch 22, the same effects as those of the above-described fourth magnet insertion hole 14 can also be obtained.

[0087] In addition, in the first embodiment, as described above, the first straight line L4a is arranged so as to be adjacent to the gap portion 10a in the fourth magnet insertion hole 14 where the permanent magnet 2 is not arranged. Thus, for the fourth bridge portion 34 formed by the first straight line L4a, the influence on the mechanical strength of the rotor core 1 caused by the shape change due to its arrangement adjacent to the gap portion 10a in the fourth magnet insertion hole 14 is particularly large. Therefore, it is possible to effectively reduce the amount of shape change formed by the change of the radius R of the circle corresponding to the first arc-shaped portion L4c and the radius R of the circle corresponding to the second arc-shaped portion L4d within the tolerance range ΔR (range of manufacturing errors) for each of the fourth bridge portions 34 formed by the first straight line L4a. In addition, at the sixth magnet insertion hole 16, the same effects as those of the above-described fourth magnet insertion hole 14 can also be obtained.

[0088] In addition, in the first embodiment, as described above, the first straight line L4a is provided so as to form the fourth bridge portion 34 located between the adjacent fourth magnet insertion holes 14 and second magnet insertion holes 12 arranged in a V shape. Thus, since the included angle A41 formed by the second straight line L4b and the first straight line L4a forming the fourth bridge portion 34 located between the adjacent fourth magnet insertion holes 14 and second magnet insertion holes 12 arranged in a V shape is a relatively small acute angle, it is possible to effectively reduce the amount of shape change formed by the change of the radius R of the circle corresponding to the first arc-shaped portion L4c and the radius R of the circle corresponding to the second arc-shaped portion L4d within the tolerance range ΔR (range of manufacturing errors) respectively.

[0089] [Second Embodiment]

[0090] Refer to Figure 5 The structure of the rotor 200 in the second embodiment of the present invention will be described. In addition, in the figure, the same reference numerals are given to the same parts as those in the first embodiment described above.

[0091] (Overall Structure of Rotor)

[0092] As Figure 5 shown, the rotor 200 includes a rotor core 201.

[0093] <Structure of Magnet Insertion Hole>

[0094] The rotor core 201 includes magnet insertion holes 210. The magnet insertion holes 210 include second magnet insertion holes 212, fourth magnet insertion holes 214, and sixth magnet insertion holes 216.

[0095] <Structure of Notch>

[0096] The rotor core 201 includes a notch 220. The notch 220 includes a second notch 222.

[0097] <Structure of Bridge Portion>

[0098] The rotor core 201 includes a bridge portion 230. The bridge portion 230 includes a fourth bridge portion 234 and an eighth bridge portion 238.

[0099] (Details of Magnet Insertion Hole)

[0100] <Fourth Magnet Insertion Hole>

[0101] As Figure 5As shown, when viewed from the Z direction, at the side surface of the fourth magnet insertion hole 214, there are provided a first straight line L4a forming the fourth bridge portion 234, a second straight line L4b arranged to extend in the direction along the long side of the permanent magnet 2, a first arc-shaped portion L24c connected to the first straight line L4a and arranged between the first straight line L4a and the second straight line L4b, a second arc-shaped portion L24d connected to the second straight line L4b and arranged between the first straight line L4a and the second straight line L4b, and an inter-arc curve portion L24e connected to the first arc-shaped portion L24c and connected to the second arc-shaped portion L24d and having a curvature smaller than that of the first arc-shaped portion L24c and the second arc-shaped portion L24d. That is, at the side surface of the fourth magnet insertion hole 214, the first straight line L4a, the first arc-shaped portion L24c, the inter-arc curve portion L24e, the second arc-shaped portion L24d, and the second straight line L4b are sequentially connected.

[0102] In order to prevent the connection portion between the first straight line L4a and the first arc-shaped portion L24c from having sharp corners, the first arc-shaped portion L24c is connected to the first straight line L4a such that the first straight line L4a becomes the tangent of the first arc-shaped portion L24c. That is, the first straight line L4a and the first arc-shaped portion L24c are smoothly connected. In addition, in order to prevent the connection portion between the inter-arc curve portion L24e and the first arc-shaped portion L24c from having sharp corners, the first arc-shaped portion L24c is connected to the inter-arc curve portion L24e such that the inter-arc curve portion L24e becomes the tangent of the first arc-shaped portion L24c. That is, the inter-arc curve portion L24e and the first arc-shaped portion L24c are smoothly connected. In addition, in order to prevent the connection portion between the inter-arc curve portion L24e and the second arc-shaped portion L24d from having sharp corners, the second arc-shaped portion L24d is connected to the inter-arc curve portion L24e such that the inter-arc curve portion L24e becomes the tangent of the second arc-shaped portion L24d. That is, the inter-arc curve portion L24e and the second arc-shaped portion L24d are smoothly connected. In addition, in order to prevent the connection portion between the second straight line L4b and the second arc-shaped portion L24d from having sharp corners, the second arc-shaped portion L24d is connected to the second straight line L4b such that the second straight line L4b becomes the tangent of the second arc-shaped portion L24d. That is, the second straight line L4b and the second arc-shaped portion L24d are smoothly connected.

[0103] In addition, in order to smoothly connect the curved portion L24e between the arcs and the first arc-shaped portion L24c, and to smoothly connect the curved portion L24e between the arcs and the second arc-shaped portion L24d, the first arc-shaped portion L24c, the curved portion L24e between the arcs, and the second arc-shaped portion L24d are formed such that, if the radius of the first arc-shaped portion L24c is set as r1, the radius of the second arc-shaped portion L24d is set as r2, the distance between the center of the circle corresponding to the first arc-shaped portion L24c and the center of the circle corresponding to the second arc-shaped portion L24d is set as L, the radius of the curved portion L24e between the arcs is set as R, and the angle formed by the first straight line L4a and the second straight line L4b is set as θ, then 2×R≥r1+r2+(L / cos(2-θ / 2)) holds.

[0104] The angle A242 formed by the tangent line at the connecting portion between the curved portion L24e between the arcs and the first arc-shaped portion L24c and the first straight line L4a is an obtuse angle. In addition, the angle A243 formed by the tangent line at the connecting portion between the curved portion L24e between the arcs and the second arc-shaped portion L24d and the second straight line L4b is an obtuse angle.

[0105] <Sixth magnet insertion hole>

[0106] When viewed from the Z direction, on the side surface of the sixth magnet insertion hole 216, there are provided a first straight line L6a forming the eighth bridge portion 238, a second straight line L6b arranged to extend in the direction along the long side of the permanent magnet 2, a first arc-shaped portion L26c connected to the first straight line L6a and arranged between the first straight line L6a and the second straight line L6b, a second arc-shaped portion L26d connected to the second straight line L6b and arranged between the first straight line L6a and the second straight line L6b, and a curved portion L26e between the arcs that is connected to the first arc-shaped portion L26c and connected to the second arc-shaped portion L26d and has a smaller curvature than the first arc-shaped portion L26c and the second arc-shaped portion L26d. That is, on the side surface of the sixth magnet insertion hole 216, the first straight line L6a, the first arc-shaped portion L26c, the curved portion L26e between the arcs, the second arc-shaped portion L26d, and the second straight line L6b are sequentially connected.

[0107] In order to prevent sharp corners at the connection between the first straight line L6a and the first arc-shaped portion L26c, the first straight line L6a and the first arc-shaped portion L26c are smoothly connected. Additionally, in order to prevent sharp corners at the connection between the inter-arc curve portion L26e and the first arc-shaped portion L26c, the inter-arc curve portion L26e and the first arc-shaped portion L26c are smoothly connected. Further, in order to prevent sharp corners at the connection between the inter-arc curve portion L26e and the second arc-shaped portion L26d, the inter-arc curve portion L26e and the second arc-shaped portion L26d are smoothly connected. Moreover, in order to prevent sharp corners at the connection between the second straight line L6b and the second arc-shaped portion L26d, the second straight line L4b and the second arc-shaped portion L26d are smoothly connected.

[0108] Furthermore, in order to smoothly connect the inter-arc curve portion L26e and the first arc-shaped portion L26c, and to smoothly connect the inter-arc curve portion L26e and the second arc-shaped portion L26d, the first arc-shaped portion L26c, the inter-arc curve portion L26e, and the second arc-shaped portion L26d are formed such that if the radius of the first arc-shaped portion L26c is set as r1, the radius of the second arc-shaped portion L26d is set as r2, the distance between the center of the circle corresponding to the first arc-shaped portion L26c and the center of the circle corresponding to the second arc-shaped portion L26d is set as L, the radius of the inter-arc curve portion L26e is set as R, and the angle formed by the first straight line L4a and the second straight line L4b is set as θ, then 2×R≥r1+r2+(L / cos(2-θ / 2)) holds.

[0109] The angle A262 formed by the tangent at the connection between the inter-arc curve portion L26e and the first arc-shaped portion L26c and the first straight line L6a is an obtuse angle. Additionally, the angle A263 formed by the tangent at the connection between the inter-arc curve portion L26e and the second arc-shaped portion L26d and the second straight line L6b is an obtuse angle.

[0110] (Details of the notch)

[0111] When observed from the Z direction, at the side surface of the second notch 222, there are provided a first straight line L2a forming the eighth bridge portion 238, a second straight line L2b disposed to face the first straight line L2a in the second notch 222, a first arc-shaped portion L22c connected to the first straight line L2a and disposed between the first straight line L2a and the second straight line L2b, a second arc-shaped portion L22d connected to the second straight line L2b and disposed between the first straight line L2a and the second straight line L2b, and an inter-arc curve portion L22e having a smaller curvature than the first arc-shaped portion L22c and the second arc-shaped portion L22d and connected to the first arc-shaped portion L22c and the second arc-shaped portion L22d. That is, at the side surface of the second notch 222, the first straight line L2a, the first arc-shaped portion L22c, the inter-arc curve portion L22e, the second arc-shaped portion L22d, and the second straight line L2b are sequentially connected.

[0112] In order to prevent the connection portion between the first straight line L2a and the first arc-shaped portion L22c from having sharp corners, the first arc-shaped portion L22c is connected to the first straight line L2a in such a manner that the first straight line L2a becomes a tangent line of the first arc-shaped portion L22c. That is, the first straight line L2a and the first arc-shaped portion L22c are smoothly connected. In addition, in order to prevent the connection portion between the inter-arc curve portion L22e and the first arc-shaped portion L22c from having sharp corners, the first arc-shaped portion L22c is connected to the inter-arc curve portion L22e in such a manner that the inter-arc curve portion L22e becomes a tangent line of the first arc-shaped portion L22c. That is, the inter-arc curve portion L22e and the first arc-shaped portion L22c are smoothly connected. In addition, in order to prevent the connection portion between the inter-arc curve portion L22e and the second arc-shaped portion L22d from having sharp corners, the second arc-shaped portion L22d is connected to the inter-arc curve portion L22e in such a manner that the inter-arc curve portion L22e becomes a tangent line of the second arc-shaped portion L22d. That is, the inter-arc curve portion L22e and the second arc-shaped portion L22d are smoothly connected. In addition, in order to prevent the connection portion between the second straight line L2b and the second arc-shaped portion L22d from having sharp corners, the second arc-shaped portion L22d is connected to the second straight line L2b in such a manner that the second straight line L2b becomes a tangent line of the second arc-shaped portion L22d. That is, the second straight line L2b and the second arc-shaped portion L22d are smoothly connected.

[0113] In addition, in order to smoothly connect the curved portion L22e between the arcs and the first arc-shaped portion L22c, and to smoothly connect the curved portion L22e between the arcs and the second arc-shaped portion L22d, the first arc-shaped portion L22c, the curved portion L22e between the arcs, and the second arc-shaped portion L22d are formed such that, if the radius of the first arc-shaped portion L22c is set as r1, the radius of the second arc-shaped portion L22d is set as r2, the distance between the center of the circle corresponding to the first arc-shaped portion L22c and the center of the circle corresponding to the second arc-shaped portion L26d is set as L, the radius of the curved portion L22e between the arcs is set as R, and the angle formed by the first straight line L4a and the second straight line L4b is set as θ, then 2×R≥r1+r2+(L / cos(2-θ / 2)) holds.

[0114] The angle A222 formed by the tangent line at the connection portion between the curved portion L22e between the arcs and the first arc-shaped portion L22c and the first straight line L2a is an obtuse angle. In addition, the angle A223 formed by the tangent line at the connection portion between the curved portion L22e between the arcs and the second arc-shaped portion L22d and the second straight line L2b is an obtuse angle.

[0115] In addition, other structures of the rotor 200 of the second embodiment are the same as those of the rotor 100 of the first embodiment described above.

[0116] (Effect of the second embodiment)

[0117] In the second embodiment, the following effects can be obtained.

[0118] In the second embodiment, as described above, when viewed from the Z direction, on the side surface of the fourth magnet insertion hole 214, there are provided a first straight line L4a forming the fourth bridge portion 234, a second straight line L4b arranged so as to extend in the direction along the long side of the permanent magnet 2, a first arc-shaped portion L24c connected to the first straight line L4a and arranged between the first straight line L4a and the second straight line L4b, a second arc-shaped portion L24d connected to the second straight line L4b and arranged between the first straight line L4a and the second straight line L4b, and an inter-arc curve portion L24e connected to the first arc-shaped portion L24c and connected to the second arc-shaped portion L24d and having a smaller curvature than the first arc-shaped portion L24c and the second arc-shaped portion L24d. Thus, between the first straight line L4a and the second straight line L4b on the side surface of the fourth magnet insertion hole 214, two arc-shaped portions can be formed, namely, a first arc-shaped portion L24c connected to the first straight line L4a and connected to the inter-arc curve portion L24e, and a second arc-shaped portion L24d connected to the second straight line L4b and connected to the inter-arc curve portion L24e. In this case, since the tangents at the connection portions between the inter-arc curve portion L24e and the first arc-shaped portion L24c and between the inter-arc curve portion L24e and the second arc-shaped portion L24d extend in a direction intersecting the first straight line L4a and the second straight line L4b, the angle A242 formed by the tangent at the connection portion between the inter-arc curve portion L24e and the first arc-shaped portion L24c and the first straight line L4a and the angle A243 formed by the tangent at the connection portion between the inter-arc curve portion L24e and the second arc-shaped portion L24d and the second straight line L4b are larger than the angle A41 formed by the first straight line L4a and the second straight line L4b. Here, the closer the absolute value of the angle θ formed by the straight line connected to one end of the arc-shaped portion CA and the tangent of the connection portion connecting the arc-shaped portion and the curve having a smaller curvature than the arc-shaped portion and connected to the other end of the arc-shaped portion is to 0 degrees (the smaller), the larger the position change amount ΔC of the arc-shaped portion CA in the protruding direction of the arc-shaped portion CA formed as the radius R of the circle corresponding to the arc-shaped portion CA changes within the tolerance range ΔR (the range of manufacturing errors). Therefore, compared with the case where only one arc-shaped portion device is provided between the first straight line L4a and the second straight line L4b on the side surface of the fourth magnet insertion hole 214, the shape change amount caused by the change of the radius R of the circle corresponding to the first arc-shaped portion L24c and the radius R of the circle corresponding to the second arc-shaped portion L24d within the tolerance range ΔR of the fourth bridge portion 234 formed by the first straight line L4a can be reduced. As a result, it is possible to suppress the increase in the mechanical strength difference between the rotor cores 1 due to the change in the shape of the fourth bridge portion 234 and the occurrence of magnetic flux leakage at the fourth bridge portion 234.In addition, at the sixth magnet insertion hole 216 and the second notch 222, the same effects as those of the fourth magnet insertion hole 214 described above can also be obtained.

[0119] In addition, in the second embodiment, as described above, the included angle A242 formed by the tangent line at the connecting portion between the inter-arc curve portion L24e and the first arc-shaped portion L24c and the first straight line L4a is an obtuse angle. In addition, the included angle A243 formed by the tangent line at the connecting portion between the inter-arc curve portion L24e and the second arc-shaped portion L24d and the second straight line L4b is an obtuse angle. Thus, since the included angle A242 formed by the tangent line at the connecting portion between the inter-arc curve portion L24e and the first arc-shaped portion L24c and the first straight line L4a and the included angle A243 formed by the tangent line at the connecting portion between the inter-arc curve portion L24e and the second arc-shaped portion L24d and the second straight line L4b are relatively large obtuse angles, the shape change amount formed by the change of the radius R of the circle corresponding to the first arc-shaped portion L24c and the radius R of the circle corresponding to the second arc-shaped portion L24d within the tolerance range ΔR (range of manufacturing error) of each of the fourth bridge portion 234 formed by the first straight line L4a can be sufficiently reduced. In addition, at the sixth magnet insertion hole 216 and the second notch 222, the same effects as those of the fourth magnet insertion hole 214 described above can also be obtained.

[0120] In addition, other effects of the second embodiment are the same as those of the first embodiment described above.

[0121] [Modification Example]

[0122] In addition, the embodiments disclosed this time should be considered as illustrative in all aspects and not restrictive. The scope of the present invention is not shown by the description of the above embodiments, but by the claims, and also includes all changes (modification examples) within the meaning and scope equivalent to the scope of the claims.

[0123] For example, in the first and second embodiments described above, an example is shown in which the first straight line L2a is arranged to form the eighth bridge portion 38 (238) located between the adjacent second notches 22 (222) and the sixth magnet insertion hole 16 (216) arranged in a V shape, but the present invention is not limited thereto. In the present invention, the first straight line L2a may not be arranged to form the eighth bridge portion 38 (238) located between the adjacent second notches 22 (222) and the sixth magnet insertion hole 16 (216) arranged in a V shape, and the first straight line may be arranged to form the seventh bridge portion 37 located between the first notch 21 and the fifth magnet insertion hole 15 arranged in a V shape.

[0124] In addition, in the above-described first and second embodiments, an example is shown in which the first straight line L4a is provided in such a manner as to form the fourth bridge portion 34 (234) located between the adjacent fourth magnet insertion holes 14 (214) and second magnet insertion holes 12 (212) arranged in a V shape, and the first straight line L6a is provided in such a manner as to form the eighth bridge portion 38 (238) located between the adjacent sixth magnet insertion holes 16 (216) and second notches 22 (222) arranged in a V shape. However, the present invention is not limited thereto. In the present invention, the first straight line L4a may not be provided in such a manner as to form the fourth bridge portion 34 (234) located between the adjacent fourth magnet insertion holes 14 (214) and second magnet insertion holes 12 (212) arranged in a V shape, the first straight line L6a may not be provided in such a manner as to form the eighth bridge portion 38 (238) located between the adjacent sixth magnet insertion holes 16 (216) and second notches 22 (222) arranged in a V shape, and the first straight line may be provided in such a manner as to form a bridge portion other than the fourth bridge portion 34 (234) and the sixth bridge portion 36 (236) located between the adjacent magnet insertion holes arranged in a V shape.

[0125] In addition, in the above-described first and second embodiments, an example is shown in which the first straight line L4a is provided in such a manner as to be adjacent to the void portion 10a in the fourth magnet insertion hole 14 (214) where the permanent magnet 2 is not arranged, and the first straight line L6a is provided in such a manner as to be adjacent to the void portion 10a in the sixth magnet insertion hole 16 (216) where the permanent magnet 2 is not arranged. However, the present invention is not limited thereto. In the present invention, the first straight line L4a may not be provided in such a manner as to be adjacent to the void portion 10a in the fourth magnet insertion hole 14 (214) where the permanent magnet 2 is not arranged, the first straight line L6a may not be provided in such a manner as to be adjacent to the void portion 10a in the sixth magnet insertion hole 16 (216) where the permanent magnet 2 is not arranged, and the first straight line may be provided in such a manner as to be adjacent to the void portion 10a in the magnet insertion hole 10 (210) where the permanent magnet 2 is not arranged, other than the fourth magnet insertion hole 14 (214) and the sixth magnet insertion hole 16 (216).

[0126] In addition, in the above-described first and second embodiments, an example is shown in which the included angle A42 (A242) formed by the first straight line L4a and the straight-line portion L4e between the arcs (the tangent at the connection portion between the curved portion L24e between the arcs and the first arc-shaped portion L24c), and the included angle A43 (A243) formed by the second straight line L4b and the straight-line portion L4e between the arcs (the tangent at the connection portion between the curved portion L24e between the arcs and the second arc-shaped portion L24d) are obtuse angles, the included angle A62 (A262) formed by the first straight line L6a and the straight-line portion L6e between the arcs (the tangent at the connection portion between the curved portion L26e between the arcs and the first arc-shaped portion L26c), and the included angle A63 (A263) formed by the second straight line L6b and the straight-line portion L6e between the arcs (the tangent at the connection portion between the curved portion L26e between the arcs and the second arc-shaped portion L26d) are obtuse angles, and the included angle A22 (A222) formed by the first straight line L2a and the straight-line portion L2e between the arcs (the tangent at the connection portion between the curved portion L22e between the arcs and the first arc-shaped portion L22c), and the included angle A23 (A223) formed by the second straight line L2b and the straight-line portion L2e between the arcs (the tangent at the connection portion between the curved portion L22e between the arcs and the second arc-shaped portion L22d) are obtuse angles. However, the present invention is not limited thereto.In the present invention, the included angle A42 (A242) formed by the first straight line L4a and the straight-line portion L4e between the arcs (the tangent at the connection portion between the curved portion L24e between the arcs and the first arc-shaped portion L24c), and the included angle A43 (A243) formed by the second straight line L4b and the straight-line portion L4e between the arcs (the tangent at the connection portion between the curved portion L24e between the arcs and the second arc-shaped portion L24d) may also be acute angles. The included angle A62 (A262) formed by the first straight line L6a and the straight-line portion L6e between the arcs (the tangent at the connection portion between the curved portion L26e between the arcs and the first arc-shaped portion L26c), and the included angle A63 (A263) formed by the second straight line L6b and the straight-line portion L6e between the arcs (the tangent at the connection portion between the curved portion L26e between the arcs and the second arc-shaped portion L26d) may also be acute angles. The included angle A22 (A222) formed by the first straight line L2a and the straight-line portion L2e between the arcs (the tangent at the connection portion between the curved portion L22e between the arcs and the first arc-shaped portion L22c), and the included angle A23 (A223) formed by the second straight line L2b and the straight-line portion L2e between the arcs (the tangent at the connection portion between the curved portion L22e between the arcs and the second arc-shaped portion L22d) may also be acute angles. At the magnet insertion holes 10 (210) other than the fourth magnet insertion hole 14 (214) and the sixth magnet insertion hole 16 (216), the included angle formed by the first straight line and the straight-line portion between the arcs (the tangent at the connection portion between the curved portion between the arcs and the first arc-shaped portion), and the included angle formed by the second straight line and the straight-line portion between the arcs (the tangent at the connection portion between the curved portion between the arcs and the second arc-shaped portion) may also be obtuse angles. At the first notch 21, the included angle formed by the first straight line and the straight-line portion between the arcs (the tangent at the connection portion between the curved portion between the arcs and the first arc-shaped portion), and the included angle formed by the second straight line and the straight-line portion between the arcs (the tangent at the connection portion between the curved portion between the arcs and the second arc-shaped portion) may also be obtuse angles.

[0127] In addition, in the above-described first and second embodiments, an example is shown in which the included angle A41 formed by the first straight line L4a and the second straight line L4b is an acute angle, the included angle A61 formed by the first straight line L6a and the second straight line L6b is an acute angle, and the included angle A21 formed by the first straight line L2a and the second straight line L2b is an acute angle. However, the present invention is not limited thereto. In the present invention, the included angle A41 formed by the first straight line L4a and the second straight line L4b may also be an obtuse angle, the included angle A61 formed by the first straight line L6a and the second straight line L6b may also be an obtuse angle, and the included angle A21 formed by the first straight line L2a and the second straight line L2b may also be an obtuse angle. At the magnet insertion holes 10 (210) and the first notch 21 other than the fourth magnet insertion hole 14 (214) and the sixth magnet insertion hole 16 (216), the included angle formed by the first straight line and the second straight line may also be an acute angle.

[0128] Description of reference numerals:

[0129] 1, 201... Rotor core; 1a... Outer peripheral portion (of the rotor core); 2... Permanent magnet; 10, 210... Magnet insertion hole; 10a... Gap portion (on the bridge portion side of the magnet insertion hole adjacent to the permanent magnet); 30, 230... Bridge portion; 100, 200... Rotor; A41, A61... Included angle (formed by the first straight line and the second straight line); A42, A43... Included angle (formed by the first straight line and the straight-line portion between the arcs); A62, A63... Included angle (formed by the second straight line and the straight-line portion between the arcs); A242, A243... Included angle (formed by the first straight line and the curved-line portion between the arcs); A262, A263... Included angle (formed by the second straight line and the curved-line portion between the arcs); L4a, L6a... First straight line; L4b, L6b... Second straight line; L4c, L6c, L24c, L26c... First arc-shaped portion; L4d, L6d, L24d, L26d... Second arc-shaped portion; L4e, L6e... Straight-line portion between the arcs; L24e, L26e... Curved-line portion between the arcs.

Claims

1. A rotor, wherein, it includes: a rotor core including magnet insertion holes and bridge portions provided adjacent to the magnet insertion holes; and permanent magnets disposed in the magnet insertion holes, when viewed axially, on the side surface of the magnet insertion hole, there are provided a first straight line forming the bridge portion, a second straight line arranged to extend in a direction along the long side of the permanent magnet, a first arc-shaped portion connected to the first straight line and disposed between the first straight line and the second straight line, and a second arc-shaped portion connected to the second straight line and disposed between the first straight line and the second straight line, when viewed axially, on the side surface of the magnet insertion hole, there is also provided an inter-arc straight portion connecting the first arc-shaped portion and the second arc-shaped portion or an inter-arc curved portion having a curvature smaller than that of the first arc-shaped portion and the second arc-shaped portion.

2. The rotor according to claim 1, wherein, the included angle formed by the first straight line and the second straight line is an acute angle.

3. The rotor according to claim 1, wherein, the included angle formed by the tangent at the connecting portion between the inter-arc straight portion and the first arc-shaped portion and the first straight line, and the included angle formed by the tangent at the connecting portion between the inter-arc straight portion and the second arc-shaped portion and the second straight line are obtuse angles, or the included angle formed by the tangent at the connecting portion between the inter-arc curved portion and the first arc-shaped portion and the first straight line, and the included angle formed by the tangent at the connecting portion between the inter-arc curved portion and the second arc-shaped portion and the second straight line are obtuse angles.

4. The rotor according to claim 1, wherein, the first straight line is provided adjacent to a gap portion in the magnet insertion hole where no permanent magnet is disposed.

5. The rotor according to claim 1, wherein, the first straight line is provided to form the bridge portion located between adjacent magnet insertion holes arranged in a V shape.

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