ROTOR CORE, ROTOR, AND ROTATING ELECTRIC MACHINE

Abstract

This rotor core is provided with a plurality of holes in which permanent magnets are installed, wherein: in a cross section perpendicular to a rotational axis, at least one of the plurality of holes includes a first end portion positioned on a leading side in a direction of rotation, in a left-right direction which is the direction of both left and right sides with respect to a magnetization direction of the permanent magnet, and a second end portion positioned on a trailing side in the direction of rotation in the left-right direction; the first end portion opens in an outer circumferential surface, and a length of the opening in a circumferential direction is greater than a length of the second end portion in the circumferential direction; in the cross section, the hole that opens at the first end portion has an inside space the length of which in a width direction is equivalent to a length corresponding to a length of the permanent magnet in a magnetization direction, and a first outside space which communicates with the inside space, includes the first end portion as an end portion of the hole in the left-right direction, and is wider than the inside space; and the first end portion is arranged offset toward the trailing side in the direction of rotation relative to a central position, in the circumferential direction, of the inside space at the position communicating with the first outside space.

Description

[Technical field]

[0001] The present disclosure relates to a rotor core, a rotor, and a rotating electric machine. [Background technology]

[0002] In a rotating electric machine with embedded permanent magnets, such as an Interior Permanent Magnet Synchronous Motor (IPMSM), a permanent magnet is embedded in a rotor core and a flux barrier is formed near the permanent magnet. The flux barrier is intended to control the flow of magnetic flux in the rotating electric machine and improve the characteristics of the rotating electric machine.

[0003] JP 2013-99047 A discloses that by connecting the magnet insertion holes provided in the rotor core to the outer periphery of the rotor core, the magnetic flux emanating from the permanent magnet is prevented from passing around the permanent magnet within the rotor core and causing a short circuit. Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the technology described in JP 2013-99047 A, when the magnet insertion holes provided in the rotor core are connected to the outer periphery of the rotor core, only the magnetic short circuit of the magnetic flux inside the rotor core is taken into consideration, and therefore the torque of the rotating electric machine cannot be sufficiently increased. The present disclosure has been made in consideration of the above-mentioned problems, and has an object to increase the torque of a rotating electric machine. [Means for solving the problem]

[0005] A rotor core according to an embodiment of the present disclosure includes a plurality of holes in which permanent magnets are disposed, In a cross section perpendicular to a rotation axis that is the center of rotation, at least one of the plurality of holes includes a first end portion located at the leading end of the rotation direction in a left-right direction that is a direction on both the left and right sides of the magnetization direction of the permanent magnet, and a second end portion located at the trailing end of the rotation direction in the left-right direction, the first end portion is open to an outer circumferential surface, and a circumferential length of the opening is longer than a circumferential length of the second end portion; In the cross section, the hole with the first end opening has an inner space whose widthwise length is equal to a length corresponding to a length in the magnetization direction of the permanent magnet, and a first outer space that communicates with the inner space, has the first end as one of the left and right ends of the hole, and is wider than the inner space, The first end portion is disposed so as to be offset rearward in the rotational direction with respect to a circumferential center position of the inner space at a position where the inner space communicates with the first outer space. Effect of the Invention

[0006] According to one aspect of the present disclosure, the torque of a rotating electric machine can be increased. [Brief description of the drawings]

[0007] [Figure 1] FIG. 2 is a diagram illustrating an example of a configuration of an IPMSM. [Diagram 2] FIG. 2 is a diagram showing a first example of a rotor configuration, corresponding to the rotor in FIG. 1. [Diagram 3] FIG. 3 is a diagram showing a first example of the configuration of a rotor core, which corresponds to the rotor core in FIG. 2. [Figure 4] 11A and 11B are diagrams illustrating a first example of an inner space and a first outer space. [Figure 5A] 10A and 10B are diagrams illustrating an example of differences in magnetic flux flow due to differences in the first ends of holes. [Figure 5B] 10A and 10B are diagrams illustrating an example of differences in magnetic flux flow due to differences in the first ends of holes. [Figure 5C] 10A and 10B are diagrams illustrating an example of differences in magnetic flux flow due to differences in the first ends of holes. [Figure 6] 4A to 4C are diagrams illustrating an example of an inner space, a first outer space, and a second outer space. [Figure 7A] 11A and 11B are diagrams illustrating an example of differences in magnetic flux flow due to differences in the second ends of holes. [Figure 7B] 11A and 11B are diagrams illustrating an example of differences in magnetic flux flow due to differences in the second ends of holes. [Figure 7C] 11A and 11B are diagrams illustrating an example of differences in magnetic flux flow due to differences in the second ends of holes. [Figure 8] FIG. 11 is a diagram showing a second example of a rotor configuration. [Figure 9] FIG. 10 is a diagram showing a second example of the configuration of a rotor core, and is a diagram for the rotor of FIG. 8. [Figure 10] 13A and 13B are diagrams illustrating a second example of the inner space and the first outer space. [Figure 11] FIG. 4 is a diagram showing a configuration of a rotor of Comparative Example 1. [Figure 12] FIG. 11 is a diagram showing a configuration of a rotor according to a second comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In addition, the fact that the length, position, size, interval, etc. of the objects being compared are the same includes not only being strictly the same, but also being different within the scope of the gist of this disclosure (for example, being different within the tolerance range determined at the time of design). In each figure, the xyz coordinates indicate the relationship of the orientation in each figure. In the xyz coordinates, a circle with a black circle indicates that the direction from the back to the front of the paper is the positive direction.

[0009] (First embodiment) First, a first embodiment will be described. In this embodiment, a rotating electric machine is an IPMSM. Fig. 1 is a diagram showing an example of the configuration of an IPMSM 100. Fig. 1 is a cross-sectional view of the IPMSM 100 taken perpendicular to a center line O (the rotation axis of a rotor 110) of the IPMSM 100. In Fig. 1, the IPMSM 100 includes a rotor 110 and a stator 120.

[0010] Stator 120 includes stator core 121 and a stator coil (not shown) for generating a rotating magnetic field. Note that, in order to avoid complicating the notation, the stator coil included in stator 120 is not shown in Fig. 1, but the stator coil is disposed in slot 122 of stator core 121 (note that only one of six slots is marked in Fig. 1).

[0011] The rotor 110 rotates about the center line O of the rotor 110 as the rotation axis. In this embodiment, a case is illustrated in which the rotor 110 rotates in the direction of the arrow shown in FIG. 1 (i.e., counterclockwise on the paper), and does not rotate in the opposite direction to the direction of the arrow shown in FIG. 1 (i.e., clockwise on the paper). FIG. 2 is a diagram showing an example of the configuration of the rotor 110. Like FIG. 1, FIG. 2 is a cross-sectional view of the rotor 110 cut perpendicularly to the center line O of the rotor 110. The center line O of the rotor 110 and the center line O of the IPMSM 100 coincide with each other.

[0012] As shown in FIG. 2, the rotor 110 includes a rotor core 111 and a plurality of permanent magnets 112 (here, one permanent magnet per pole). The rotor core 111 includes a soft magnetic material portion, which is a portion of the rotor core 111 formed of a soft magnetic material, and a plurality of holes. The soft magnetic material portion is formed, for example, by laminating a plurality of electromagnetic steel plates along the center line O of the rotor 110. However, it is not necessarily required to form the soft magnetic material portion by laminating a plurality of electromagnetic steel plates. The rotor core 111 may be, for example, a dust core, an amorphous core, or a nanocrystalline core. When the rotor core 111 is a dust core, an amorphous core, or a nanocrystalline core, the soft magnetic material portion of the rotor core 111 is formed using insulating-coated soft magnetic particles, an amorphous alloy, or a nanocrystalline alloy, respectively.

[0013] A plurality of holes extending along a direction (hereinafter simply referred to as the z-axis direction) parallel to the center line O of the rotor core 111 are formed in the rotor core 111. In this embodiment, the case where the holes are through holes penetrating in the z-axis direction is illustrated.

[0014] The multiple permanent magnets 112 are installed (embedded) in the rotor core 111 by being inserted into holes formed in the rotor core 111. Fig. 2 illustrates an example in which magnetic flux flows in and out of magnetic pole faces 201 (201a, 201b) of the permanent magnet 112. The direction perpendicular to the magnetic pole faces 201 (the direction of the double-headed arrows crossing the permanent magnet 112 in the radial direction of the rotor core 111 in Fig. 2) is the magnetization direction Dm of the permanent magnet 112. The radial direction is the direction extending radially on the xy plane from the center line O (the rotation axis of the rotor 110).

[0015] In the hole where the permanent magnet 112 is installed, the region where the permanent magnet 112 does not exist becomes a flux barrier 113 (113a to 113b). No tangible object exists in the flux barrier 113, and it becomes a void portion (in other words, an air region). The flux barrier 113 is a region where the magnetic flux does not pass or passes through it more difficultly than the surrounding region. However, a non-magnetic material may be installed in the flux barrier 113. In addition to the flux barrier 113, holes 114 (114a to 114d) are formed in the rotor core 111. The holes 114a to 114c are formed to function as flux barriers or to accommodate rivets (not shown). The rivets are used, for example, to fix the rotor 110 to end plates (not shown) that are arranged at both ends of the rotor 110 in the z-axis direction. In addition, a hole 114d that penetrates the rotor core 111 in the z-axis direction is formed on the inner peripheral side of the rotor core 111. A shaft (not shown) or the like is placed in the hole 114d.

[0016] In this embodiment, the shape of a cross section of rotor 110 (hereinafter referred to as rotor cross section) taken perpendicular to the center line O of rotor 110 is shown in Figure 2 at any position in the z-axis direction of rotor 110.

[0017] 1 and 2 illustrate an example in which the number of poles of the IPMSM 100 is four. In FIG. 2, the range indicated by the double-headed arrow labeled "one pole" is the portion constituting one pole of the IPMSM 100. One permanent magnet 112 is embedded per pole, and a total of four permanent magnets are embedded in the hole of the rotor core 111. This number of poles and the number and arrangement of the permanent magnets 112 per pole are merely examples and can be determined arbitrarily. In FIG. 2, to avoid complicating the notation, reference numerals are attached only to the portion constituting one pole of the rotor 110, and reference numerals are omitted for the portions constituting the other three poles of the rotor 110. When the number of poles of the IPMSM 100 is n poles (where n is an integer of 2 or more, n=4 in the example illustrated in FIG. 1 and FIG. 2), the IPMSM 100 generally has an n-fold rotational symmetry relationship with the center line O of the IPMSM 100 as the axis of rotational symmetry.

[0018] Fig. 3 is a diagram showing an example of the configuration of rotor core 111. Like Figs. 1 and 2, Fig. 3 is a cross-sectional view of rotor core 111 taken perpendicularly to the center line O of rotor core 111. The center line O of rotor core 111 coincides with the center line O of IPMSM 100 and the center line O of rotor 110. Also, in Fig. 3, like Fig. 2, reference numerals are attached only to a portion constituting one pole of rotor core 111, and reference numerals are omitted for portions constituting the other three poles of rotor core 111.

[0019] In FIG. 3, rotor core 111 is formed with holes 310 including an area occupied by permanent magnets 112 (hereinafter referred to as a magnet-occupied area) and an area serving as flux barrier 113. In a cross section of the rotor core 111 taken perpendicularly to the center line O of the rotor core 111 (hereinafter referred to as the rotor core cross section), at least one hole 310 (all of the four holes 310 in FIG. 3) is open at a first end 311 located at the leading end in the rotation direction of the rotor core 111 among the ends in the left-right direction Ds, which are directions on both the left and right sides with respect to the magnetization direction Dm of the permanent magnet 112 at the center of the permanent magnet 112. In the example shown in FIG. 3, the left-right direction Ds of the hole 310 is the longitudinal direction of the hole 310. In FIG. 3, the left-right direction Ds of the hole 310 is indicated by a double-headed arrow line drawn next to the hole 310. On the other hand, in the rotor core cross section, the hole 310 is not open at a second end 312 on the opposite side to the first end 311 (in other words, on the trailing end side in the rotation direction of the rotor core 111). Hereinafter, the leading side of rotor core 111 in the rotation direction will also be simply referred to as the leading side, and the trailing side of rotor core 111 in the rotation direction will also be simply referred to as the trailing side.

[0020] As described above, in this embodiment, the number of poles of the IPMSM 100 is four. As shown in FIG. 3, in this embodiment, the case where all of the four holes 310 in which the permanent magnets 112 are installed are open at the first end 311 is illustrated. However, it is sufficient that at least one of the four holes 310 in which the permanent magnets 112 are installed is open at the first end 311 of the hole 310. In addition, the case where all of the four holes 310 in which the permanent magnets 112 are installed are not open at the second end 312 is illustrated. However, it is sufficient that at least one of the four holes 310 in which the permanent magnets 112 are installed is not open at the second end 312.

[0021] Fig. 1 illustrates an inner rotor type IPMSM 100. As shown in Fig. 1, the area of ​​the outer circumferential surface of the rotor 110 (rotor core 111) other than the hole 310 becomes an end face that faces the stator 120 of the rotor 110 (rotor core 111) with a gap therebetween.

[0022] Further, the leading side of the rotor core 111 in the rotational direction is the leading position side of the permanent magnet 112 when viewed in the rotational direction of the rotor 110, and the trailing side of the rotor core 111 in the rotational direction is the trailing position side of the permanent magnet 112. Specifically, in the example shown in FIG. 2, when viewed in the rotational direction of the rotor 110, the leading position of the permanent magnet 112 is on the side surface 202 of the permanent magnet 112, and the trailing position of the permanent magnet 112 is on the side surface 203 of the permanent magnet 112. Therefore, the rotor core 111 is disposed in the rotor 110 such that the leading side of the rotor core 111 in the rotational direction is on the side surface 202 side of the permanent magnet 112, and the trailing side of the rotor core 111 in the rotational direction is on the side surface 203 side of the permanent magnet 112. In the example shown in FIG. 2, the side surfaces 202 and 203 of the permanent magnet 112 are end surfaces of the magnetic pole surface 201 (201a, 201b) of the permanent magnet 112 that are located at the ends in a direction perpendicular to the magnetization direction Dm of the permanent magnet 112.

[0023] In Fig. 3, the hole 310 has an inner space 310a and a first outer space 310b. Fig. 4 is a diagram illustrating an example of the inner space 310a and the first outer space 310b. The inner space 310a is a space that, in the cross section of the rotor core, constitutes the hole 310, and has a widthwise length along the magnetization direction Dm of the permanent magnet 112 that is substantially constant and equal to the length L1 corresponding to the length of the magnetization direction Dm of the permanent magnet 112. As is clear from comparing FIG. 2 with FIG. 3 and FIG. 4, the permanent magnet 112 is installed in the inner space 310a. Therefore, the widthwise length of the magnet-occupied area of ​​the hole 310 is the same as the widthwise length L1 of the inner space 310a. The widthwise length L1 of the inner space 310a may be the same as the length of the magnetization direction Dm of the permanent magnet 112, or may be (slightly) longer than the length of the magnetization direction Dm of the permanent magnet 112 to facilitate installation of the permanent magnet 112 in the hole 310. In this embodiment, a case in which the length of the magnetization direction Dm of the permanent magnet 112 is constant is illustrated. However, the length of the magnetization direction Dm of the permanent magnet 112 does not necessarily have to be constant. If the length of the magnetization direction Dm of the permanent magnet 112 is not constant, the widthwise length of the inner space 310a does not have to be constant and must be equal to the length corresponding to the length of the magnetization direction Dm of the permanent magnet 112.

[0024] The width direction of the hole 310 is a direction perpendicular to both the left-right direction Ds of the hole 310 (the direction indicated by the double-headed arrows beside the hole 310 in FIGS. 3 and 4) and the depth direction of the hole 310 (the z-axis direction of the rotor core 111). As described above, the magnetization direction Dm of the permanent magnet 112 is the direction indicated by the double-headed arrows crossing the permanent magnet 112 in FIG. 2, and the width direction of the inner space 310a coincides with the magnetization direction Dm of the permanent magnet 112. As shown in FIG. 3, in a typical IPMSM 100, the length of the left-right direction Ds of the hole 310 in which the permanent magnet 112 is placed in the rotor core 111 is longer than the length of the hole 310 in the width direction, but the length of the left-right direction Ds of the hole 310 may be the same as or shorter than the length of the hole 310 in the width direction.

[0025] The first outer space 310b is a space that communicates between the inner space 310a and the outside of the rotor core 111 among the spaces that constitute the hole 310. The first outer space 310b is a space that communicates with the inner space 310a among the spaces that constitute the hole 310 and has the first end 311 of the hole 310 as one of the ends in the left-right direction Ds. Therefore, the end on the outer circumferential side of the first outer space 310b (in other words, the end opposite to the side that communicates with the inner space 310a) coincides with the first end 311 of the hole 310. There is no outer space on the rear side of the inner space 310a, and the end on the rear side coincides with the second end 312 of the hole 310. That is, in the cross section of the rotor core, the second end 312 of the hole 310 is not open. On the other hand, the circumferential length of the first end 311 of the hole 310 is L2.

[0026] The circumferential length L2 of the first end 311 of the hole 310 is the circumferential length in the direction from the end point 401 at the leading side of the first end 311 of the hole 310 to the end point 402 at the trailing side of the first end 311 of the hole 310. The circumferential length L2 of the first end 311 of the hole 310 may be approximated to the widthwise length of the first end 311 of the hole 310. The widthwise length of the first end 311 of the hole 310 is the straight-line distance between the end point 401 at the leading side of the first end 311 of the hole 310 and the end point 402 at the trailing side of the first end 311 of the hole 310.

[0027] As shown in Fig. 4, in this embodiment, the circumferential length L2 of the first end 311 of the hole 310 is longer than the widthwise length L1 of the inner space 310a. The reason for this is explained below. Figs. 5A, 5B, and 5C are diagrams for explaining the difference in the flow of magnetic flux due to the difference in the first end 311 of the hole 310. Note that the magnetic flux shown by the arrows in Figs. 5A, 5B, and 5C is a conceptual representation, and for example, the length and number of the arrows do not necessarily correspond to the magnitude and density of the magnetic flux.

[0028] 5A, 5B, and 5C show enlarged views of the vicinity of first end 311 of hole 310 when IPMSM 100 is in operation. 5A shows the flow of magnetic flux when it is assumed that first end 311 of hole 310 does not communicate with the outer peripheral surface of rotor core 111. As shown in FIG. 5A, if first end 311 of hole 310 is not open, the region outside first end 311 of hole 310 becomes a soft magnetic material part such as an electromagnetic steel plate, and the region inside first end 311 of hole 310 functions as a flux barrier, but the region of the soft magnetic material part becomes a bridge part, and magnetic flux 501 is generated that circulates within rotor core 111 without flowing toward stator core 121. For this reason, the torque of IPMSM 100 cannot be sufficiently increased.

[0029] 5B shows the flow of magnetic flux when the circumferential length L2 of the first end 311 of the hole 310 is approximately the same as the widthwise length L1 of the inner space 310a of the hole 310. As shown in FIG. 5B, when the first end 311 of the hole 310 is open, the return of magnetic flux through the bridge portion as shown in FIG. 5A hardly occurs. Therefore, the returning magnetic flux is directed toward the stator core 121 at an angle with respect to the radial direction of the IPMSM 100, thereby increasing the torque of the IPMSM 100. However, because the circumferential length L2 of the first end 311 of the hole 310 is short, there is a possibility that magnetic flux passing through the flux barrier 113a may occur.

[0030] 1 to 4, Fig. 5C shows the flow of magnetic flux in the case where circumferential length L2 of first end 311 of hole 310 is longer than widthwise length L1 of inner space 310a of hole 310. As shown in Fig. 5C, by making circumferential length L2 of first end 311 of hole 310 longer than widthwise length L1 of inner space 310a, it is possible to more reliably reduce the generation of magnetic flux that passes through flux barrier 113a.

[0031] Furthermore, it is preferable to make the circumferential length L2 of the first end 311 of the hole 310 longer than the widthwise length L1 of the inner space 310a by making the circumferential length of the rear side region of the first end 311 of the hole 310 longer. In this way, in the region of the soft magnetic material part on the rear side of the flux barrier 113a, it is possible to generate a large amount of magnetic flux that has an increased angle from the radial direction of the IPMSM 100 (i.e., the direction extending radially from the center line O on the xy plane) toward the front side in the circumferential direction (this corresponds to the direction of the magnetic fluxes 504 and 505 shown in FIG. 5C being inclined toward the front side in the circumferential direction more than the direction of the magnetic fluxes 502 and 503 shown in FIG. 5B). That is, when the magnetic flux density vector representing the magnetic fluxes 504 and 505 shown in FIG. 5C is expressed in an r-θ coordinate system (two-dimensional polar coordinate system) with the center line O as the origin, the θ component B of the magnetic flux density vector due to the magnetic fluxes 504 and 505 is expressed as θ This has the effect of increasing the reluctance torque of the IPMSM100, and contributes to increasing the torque of the IPMSM100.

[0032] This can also be seen from the following: When the formula for calculating torque T from Maxwell's stress tensor described in "Design and Application of AC / DC Electromagnets Using the Finite Element Method, by Takayoshi Nakata, Akiyoshi Ito, and Junhiro Kawase, August 1991, Morikita Publishing Co., Ltd." is converted to the r-θ coordinate system, torque T is expressed by the following formula (1).

[0033]

number

[0034] Here, L is the height of the rotor core (length in the z-axis direction). When the rotor core (specifically, the soft magnetic material portion of the rotor core) is made of electromagnetic steel sheets, L is the lamination thickness of the electromagnetic steel sheets. R is the radius of the rotor core. μ0 is the magnetic permeability of a vacuum. B r is the r-component (i.e., the radial component) of the magnetic flux density vector. B θis the θ component (i.e., the deflection angle component) of the magnetic flux density vector. Here, the θ direction is the positive direction counterclockwise when facing the paper surface of Figures 5A, 5B, and 5C, and coincides with the rotation direction in this embodiment. Therefore, as shown in formula (1), the θ component B of the magnetic flux density vector θ It can be seen that as increases, the torque T increases.

[0035] Therefore, it is preferable that the first end 311 of the hole 310 is as follows. First, in FIG. 4, the first outer space 310b of the hole 310 is a region wider than the inner space 310a of the hole 310. In addition, it is preferable that the first end 311 of the hole 310 is biased toward the rear side in the circumferential direction with respect to the center position 403 of the inner space 310a at the position (boundary) communicating with the first outer space 310b. In other words, it is preferable that the circumferential center position 404 of the first end 311 of the hole 310 is located toward the rear side in the circumferential direction from the circumferential center position 403 of the inner space 310a at the position communicating with the first outer space 310b. This corresponds to the circumferential center position 404 of the first end 311 of the hole 310 being located toward the rear side in the circumferential direction from the extrapolated center position 406 of the inner space 310a of the hole 310 in FIG. 4. The extrapolated center position 406 of the inner space 310a of the hole 310 is the position of the intersection between a straight line (dashed line extending from the center position 403 in FIG. 4) extending along the radial direction of the rotor core 111 from the center position 403 of the inner space 310a at the position (boundary) communicating with the first outer space 310b, and the first end portion 311 of the hole 310. In this way, a space recessed toward the center line O side from the outer peripheral surface of the other region of the rotor core 111 can be formed on the rear side of the end point 405 on the rear side of the inner space 310a. Therefore, it is possible to increase the magnetic flux density vector with a large positive θ component in the soft magnetic material portion on the rear side of the first outer space 310b. FIG. 4 illustrates such a case.

[0036] In this case, it is more preferable that the circumferential length L3 in the direction toward the rear side from the extrapolated center position 406 of the inner space 310a of the hole 310 to the end point 402 at the rear side of the first end 311 of the hole 310 is equal to or larger than the widthwise length L1 of the inner space 310a (L3≧L1). In this way, the space recessed toward the center line O side from the outer circumferential surface of the other region of the rotor core 111 can be made larger on the rear side of the end point 405 at the rear side of the inner space 310a. Therefore, the magnetic flux density vector with a large θ component can be increased on the rear side of the flux barrier 113a (first outer space 310b). FIG. 4 illustrates such a case.

[0037] Furthermore, it is more preferable that the circumferential length L4 in the direction toward the rear side from the rear end point extrapolation position 407 of the inner space 310a of the hole 310 to the end point 402 on the rear side of the first end 311 of the hole 310 is equal to or greater than the width direction length L1 of the inner space 310a (L4≧L1). The rear end point extrapolation position 407 of the inner space 310a of the hole 310 is the position of the intersection of a straight line (dashed line extending from the end point 405 in FIG. 4) extending from the end point 405 on the rear side of the inner space 310a at the position communicating with the first outer space 310b along the radial direction of the rotor core 111 and the first end 311 of the hole 310. In this way, the space recessed toward the center line O side from the outer circumferential surface of the rotor core 111 in other regions can be made even larger on the rear side of the end point 405 on the rear side of the inner space 310a. Therefore, the magnetic flux density vector with a large θ component can be further increased on the rear side of the flux barrier 113a (first outer space 310b). FIG.

[0038] As shown in FIG. 4, in the hole wall surface 310W constituting the hole 310, the rear wall surface 310W1 forming the rear side of the rotation direction of the first outer space 310b is inclined with respect to a direction perpendicular to the center line O (radial direction). Specifically, as shown in FIG. 4 and FIG. 6, the rear wall surface 310W1 is formed so that the length in the width direction of the hole 310 gradually increases toward the outer periphery. Also, the rear wall surface 310W1 is curved in a concave shape. Note that the concave curved portion formed on the rear wall surface 310W1 may be at least a part of the rear wall surface 310W1. Specifically, the rear wall surface 310W1 is formed in a stepped shape so as to be curved in a concave shape with respect to a virtual line connecting the end point 402 and the end point 405. For example, the steps may have a portion that intersects with the virtual line, but it is preferable that the portion on the rear side and / or the radially inner side with respect to the virtual line is longer than the portion on the opposite side. It should be noted that the present disclosure is not limited to this configuration, and the rear wall surface 310W1 may be linear (coincident with an imaginary straight line) or curved (a curved surface that curves in an arc shape relative to an imaginary straight line). Here, by inclining the rear wall surface 310W1 in a direction perpendicular to the center line O (radial direction), the magnetic resistance of the soft magnetic material part on the rear side of the first outer space 310b can be increased, and the magnetic flux density vector with a large positive θ component can be increased. This makes it possible to further increase the reluctance torque. Furthermore, by curving the rear wall surface 310W1 in a concave shape, the magnetic resistance of that portion can be further increased, so that the magnetic flux density vector with a large positive θ component can be further increased.

[0039] The shape and radial length of first outer space 310b are not limited to those shown in Fig. 3 and Fig. 4. For example, the shape and radial length of first outer space 310b may be determined based on the results of electromagnetic field analysis of IPMSM 100 such that the torque T of IPMSM 100 is greater when first outer space 310b is formed as described above compared to when first outer space 310b is not formed.

[0040] On the other hand, as described above, the second end 312 of the hole 310 does not communicate with the outer peripheral surface of the rotor core 111 (in other words, the end surface facing the stator 120 with a gap therebetween). Therefore, as shown in FIG. 4, the end of the inner space 310a at the rear side in the left-right direction Ds coincides with the second end 312 of the hole 310. In the rotor core 111 shown in FIG. 3, if the second end 312 of the hole 310 is opened, the region on the outer peripheral side of the rotor core 111 from the hole 310 is isolated, and the rotor core 111 has a shape in which the region is floating in the air. This reduces the mechanical strength of the rotor core 111. In such a case, for example, a measure is required to place a nonmagnetic material in the second end 312 of the hole 310 to connect the outer peripheral side region and the inner peripheral side region of the rotor core 111, and there are cases in which such an arrangement cannot be adopted as it is due to manufacturing difficulties. Therefore, in this embodiment, the second end 312 of the hole 310 is not opened.

[0041] Here, the reason why the first end 311 of the hole 310 is opened instead of the second end 312 of the hole 310 is that the magnetic flux density vector B in the θ direction is smaller in this way than in the case where the second end 312 of the hole 310 is opened instead of the first end 311 of the hole 310. θ This is because it is possible to increase the positive component of the equation. This will be explained below.

[0042] FIG. 6 is a diagram for explaining an example of the inner space 310a, the first outer space 310b, and the second outer space 310c, and corresponds to FIG. 4. FIG. 7A, FIG. 7B, and FIG. 7C are diagrams for explaining the difference in the flow of magnetic flux due to the difference in the second end 312 of the hole 310, and FIG. 7A, FIG. 7B, and FIG. 7C correspond to FIG. 5A, FIG. 5B, and FIG. 5C, respectively. That is, FIG. 7A shows the flow of magnetic flux when the second end 312 of the hole 310 is not open, as shown in FIG. 3 and FIG. 4. FIG. 7B shows the flow of magnetic flux when the second end 312 of the hole 310 is open, and the circumferential length L12 of the second end 312 of the hole 310 is approximately the same as the widthwise length L1 of the inner space 310a of the hole 310. Fig. 7C shows the flow of magnetic flux when second end 312 of hole 310 is open and circumferential length L12 of second end 312 of hole 310 is longer than widthwise length L1 of inner space 310a of hole 310. Note that in Figs. 7A, 7B, and 7C, as in Figs. 5A, 5B, and 5C, the magnetic flux indicated by the arrows is a conceptual representation, and for example, the length and number of the arrows do not necessarily correspond to the magnitude and density of the magnetic flux.

[0043] As shown in FIG. 7A, when the second end 312 of the hole 310 is not opened, the area outside the second end 312 of the hole 310 is a soft magnetic material part such as an electromagnetic steel plate. Second end 312 Although the inner region functions as a flux barrier, the soft magnetic material portion serves as a bridge portion, generating magnetic flux 701 that circulates within rotor core 111 rather than flowing toward stator core 121. This makes it difficult to increase the torque of IPMSM 100 accordingly. However, as described above, in order to prevent the region on the outer periphery of rotor core 111 from hole 310 from being suspended in midair, in this embodiment, second end 312 of hole 310 is not opened.

[0044] Here, as shown in Fig. 6, it is assumed that a second outer space 310c similar to the first outer space 310b of the first end 311 of the hole 310 is also formed at the second end 312 of the hole 310, and the circumferential length L12 of the second end 312 of the hole 310 is longer than the widthwise length L1 of the inner space 310a. The circumferential length L12 of the end 312 at the rear side of the rotor core 111 is the circumferential length in the direction toward the leading side from the end point 411 at the rear side of the second end 312 of the hole 310 to the end point 412 at the leading side of the second end 312 of the hole 310. The circumferential length L12 of the end 312 at the rear side of the rotor core 111 may be approximated to the widthwise length of the end 312 at the rear side of the rotor core 111 (the straight-line distance between the end point 411 and the end point 412).

[0045] In this case, it is preferable that the second end 312 of the hole 310 is biased toward the leading side in the circumferential direction with respect to the center position 413 of the inner space 310a at the position where the hole 310 communicates with the second outer space 310c. In other words, it is preferable that the circumferential center position 414 of the second end 312 of the hole 310 is located toward the leading side in the circumferential direction with respect to the circumferential center position 413 of the inner space 310a at the position where the hole 310 communicates with the second outer space 310c. This corresponds to the fact that the circumferential center position 414 of the second end 312 of the hole 310 is located toward the leading side in the circumferential direction with respect to the extrapolated center position 416 of the inner space 310a of the hole 310 in FIG. 6. The extrapolated center position 416 of the inner space 310a of the hole 310 is the intersection of a straight line (dashed line extending from the center position 413 in Figure 6) extending along the radial direction of the rotor core 111 from the center position 413 of the inner space 310a at the position (boundary) where it communicates with the second outer space 310c, and the second end 312 of the hole 310.

[0046] In this case, it is more preferable that the circumferential length L13 in the direction toward the leading side from the extrapolated center position 416 of the inner space 310a of the hole 310 to the end point 412 on the leading side of the second end 312 of the hole 310 is equal to or greater than the widthwise length L1 of the inner space 310a (L13≧L1). Furthermore, it is even more preferable that the circumferential length L14 in the direction toward the leading side from the extrapolated position 417 of the leading end point of the inner space 310a of the hole 310 to the end point 412 on the leading side of the second end 312 of the hole 310 is equal to or greater than the widthwise length L1 of the inner space 310a (L14≧L1). The leading end point extrapolation position 417 of the inner space 310a of the hole 310 is the position of the intersection of a straight line (dashed line extending from end point 415 in Figure 4) extending along the radial direction of the rotor core 111 from the leading end point 415 of the inner space 310a at the position where it communicates with the second outer space 310c, and the second end 312 of the hole 310.

[0047] By forming the first outer space 310b as shown in Fig. 4 and Fig. 6, the area on the rear side of the first outer space 310b is expanded. Therefore, as shown in Fig. 5B, the magnetic flux at a position close to the end point 402 on the rear side of the first outer space 310b advances from the rear side (i.e., the rear side with respect to the rotation direction of the rotor core 111) toward the stator core 121, compared to the case where the circumferential length L2 of the first end 311 of the hole 310 is approximately the same as the width direction length L1 of the magnet-occupied area of ​​the hole 310 (i.e., the width direction length of the inner space 310a) (see magnetic fluxes 502, 503 shown in Fig. 5B and magnetic fluxes 504, 505 shown in Fig. 5C). Since the rotor core 111 rotates toward the front side, the advance direction of the magnetic fluxes 504, 505 is greatly inclined with respect to the advance direction of the magnetic fluxes 502, 503, and the positive component in the θ direction of the magnetic flux density vector represented by the magnetic fluxes 504, 505 becomes large.

[0048] On the other hand, by forming second outer space 310c as shown in Fig. 6, the region on the leading side of second outer space 310c is expanded. Therefore, the magnetic flux at a position close to end point 412 on the leading side of second outer space 310c advances from the leading side (i.e., the front side with respect to the rotation direction of rotor core 111) toward stator core 121 (see magnetic fluxes 702 and 703 shown in Fig. 7B and magnetic fluxes 704 and 705 shown in Fig. 7C) compared to the case where circumferential length L12 of second end 312 of hole 310 is substantially the same as width direction length L1 of magnet occupied area of ​​hole 310 (i.e., width direction length of inner space 310a) as shown in Fig. 7B. However, because rotor core 111 rotates toward the leading side, the direction of travel of magnetic fluxes 704, 705 is not inclined as much as that of magnetic fluxes 504, 505 shown in Fig. 5C, and the increase in the positive component in the θ direction of the magnetic flux density vector represented by magnetic fluxes 704, 705 is smaller than the θ component of the magnetic flux density vector represented by magnetic fluxes 504, 505 shown in Fig. 5C. Furthermore, if second outer space 310c is formed so that L12>L1 as shown in Fig. 6, the decrease in mechanical strength of rotor core 111 will be large, and manufacturing difficulties will also increase.

[0049] As described above, because rotor core 111 rotates toward the leading side, directing the magnetic flux return via the bridge portion as shown in FIG. 5A toward stator core 121 as shown in FIG. 5C can cause the magnetic flux traveling direction to be inclined more greatly with respect to the radial direction of IPMSM 100 than directing the magnetic flux return via the bridge portion as shown in FIG. 7A toward stator core 121 as shown in FIG. 7C, and can increase the positive component of the magnetic flux density vector in the θ direction. For the above reasons, in this embodiment, the first end 311 of the hole 310 is opened, instead of the second end 312 of the hole 310.

[0050] As described above, in the present embodiment, at least one of the holes 310 in which the permanent magnets 112 are disposed is opened at the first end 311 in the cross section of the rotor core. Moreover, the circumferential length L2 of the first end 311 of the hole 310 (i.e., the circumferential length of the opening of the first end 311) is longer than the circumferential length of the opening of the second end 312. Therefore, on the first end 311 side of the hole 310, the magnetic flux 501 circulating inside the rotor core 111 can be suppressed, and the reluctance torque can be increased. Thus, the torque T of the IPMSM 100 can be increased.

[0051] Furthermore, in this embodiment, by making second end 312 of hole 310 not open in the cross section of the rotor core, circumferential length L2 of first end 311 of hole 310 (i.e., the circumferential length of the opening of first end 311) is made longer than the circumferential length of the opening of second end 312. Therefore, the torque T of IPMSM 100 and the mechanical strength of rotor core 111 can be increased without using a non-magnetic material or the like.

[0052] Furthermore, in this embodiment, in the cross section of the rotor core, the circumferential length L2 of the first end 311 of the hole 310 is longer than the length L1 in the magnetization direction Dm of the permanent magnet 112 (i.e., the widthwise length of the magnet-occupied area of ​​the hole 310 (the widthwise length of the inner space 310a)). Therefore, on the first end 311 side of the hole 310 in the left-right direction Ds, the magnetic flux 501 circulating within the rotor core 111 can be reliably suppressed, and the reluctance torque can be reliably increased.

[0053] In this embodiment, first ends 311 of all holes 310 are open in the cross section of the rotor core. Therefore, on the side of first end 311 of each hole 310, magnetic flux 501 circulating inside rotor core 111 can be more reliably suppressed, and reluctance torque can be more reliably increased.

[0054] In the present embodiment, in the cross section of the rotor core, the first end 311 of the hole 310 is biased toward the rear side in the circumferential direction with respect to the center position 403 of the inner space 310a at the position where the inner space 310a communicates with the first outer space 310b. Therefore, the reluctance torque can be made larger on the first end 311 side of the hole 310.

[0055] In the present embodiment, in the cross section of the rotor core, a circumferential length L4 in a direction toward the rear side from an extrapolated position 407 of the rear end point of the inner space 310a of the hole 310 to an end point 402 on the rear side of the first end 311 of the hole 310 is equal to or greater than the widthwise length L1 of the inner space 310a (L4≧L1). Therefore, the reluctance torque can be further increased on the side of the first end 311 of the hole 310.

[0056] Second embodiment Next, a second embodiment will be described. In the first embodiment, a case where the second end 312 of the hole 310 in which the permanent magnet 112 is placed is not open in the cross section of the rotor core is exemplified. In contrast, in the present embodiment, a case where the second end of the hole in which the permanent magnet 112 is placed is open in the cross section of the rotor core is described. As described above, the main difference between the present embodiment and the first embodiment is the second end 312 of the hole 310. Therefore, in the description of the present embodiment, the same reference numerals as those in Figs. 1 to 7C are used for the same parts as those in the first embodiment, and detailed description thereof will be omitted.

[0057] In this embodiment, the rotor 110 shown in FIG. 2 is modified as follows. FIG. 8 is a diagram showing an example of the configuration of a rotor 810. FIG. 8 is a cross-sectional view of the rotor 810 taken perpendicularly to the center line O of the rotor 810, and corresponds to FIG. 2. In this embodiment, as in the first embodiment, an example is shown in which the rotor 810 rotates in the direction of the arrow shown in FIG. 8 (i.e., counterclockwise on the paper), but does not rotate in the opposite direction to the direction of the arrow shown in FIG. 8 (i.e., clockwise on the paper).

[0058] The rotor 810 includes a rotor core 811 and a plurality of permanent magnets 112. The rotor core 811 includes a soft magnetic material portion and a plurality of holes. The soft magnetic material portion is formed, for example, by stacking a plurality of electromagnetic steel sheets along the center line O of the rotor 810. However, the soft magnetic material portion does not necessarily have to be formed by stacking a plurality of electromagnetic steel sheets. As exemplified in the first embodiment, the soft magnetic material portion may be formed of another soft magnetic material.

[0059] In the hole where the permanent magnet 112 is placed, the region where the permanent magnet 112 is not present becomes a flux barrier 813 (813a to 813b). The difference between the rotor 110 shown in FIG. 2 and the rotor 810 shown in FIG. 8 is the shape and size of the flux barrier 813b. The flux barrier 113a shown in FIG. 2 is the same as the flux barrier 813a shown in FIG. 8. As described in the first embodiment, the flux barriers 813a to 813b may be voids (i.e., air regions) or may have a non-magnetic material placed therein. However, it is preferable to place a non-magnetic material in, for example, a part or all of the region of the flux barrier 813b so that the region on the outer periphery side of the flux barrier 813 of the rotor core 811 is not isolated and the region does not appear to be floating in the air.

[0060] In this embodiment, similarly to the first embodiment, the cross-sectional shape of the rotor is illustrated in FIG. 8 at any position in the z-axis direction of the rotor 810.

[0061] 8 illustrates an example in which the number of poles of the IPMSM is four, similar to the first embodiment. In FIG. 8, similar to FIG. 2, to avoid complicating the notation, reference numerals are attached only to the portion constituting one pole of rotor 810, and reference numerals are omitted for the portions constituting the other three poles of rotor 810.

[0062] Fig. 9 is a diagram showing an example of the configuration of rotor core 811. Fig. 9 is a cross-sectional view of rotor core 811 cut perpendicularly to center line O of rotor core 811, and corresponds to Fig. 3. Note that in Fig. 9, similar to Fig. 3, reference numerals are attached only to a portion constituting one pole of rotor core 811, and reference numerals are omitted for portions constituting the other three poles of rotor core 811.

[0063] In FIG. 9, rotor core 811 is formed with hole 910 including a magnet occupied area and an area that becomes flux barrier 813. A first end 911 of the hole 910 is open in the cross section of the rotor core. A second end 912 of the hole 910 is also open in the cross section of the rotor core.

[0064] As in the first embodiment, in the present embodiment, a case is illustrated in which all of the four holes 910 in which the permanent magnets 112 are installed are open at the first end 911 of the hole 910 in the cross section of the rotor core. However, it is sufficient that the first end 911 of the hole 910 is open in at least one of the four holes 910 in which the permanent magnets 112 are installed. Similarly, a case is illustrated in which the second end 912 of the hole 910 is open in all of the four holes 910 in which the permanent magnets 112 are installed. However, it is sufficient that the second end 912 of the hole 910 is open in at least one of the four holes 910 in which the permanent magnets 112 are installed.

[0065] In Fig. 9, the hole 910 has an inner space 910a and a first outer space 910b. Fig. 10 is a diagram illustrating the inner space 910a and the first outer space 910b, and corresponds to Fig. 4. In FIG. 10, the first outer space 910b is the same as the first outer space 310b shown in FIG.

[0066] The inner space 910a is a space that, among the spaces constituting the hole 910 in the cross section of the rotor core, has a substantially constant widthwise length that is equal to the length L1 corresponding to the length of the magnetization direction Dm of the permanent magnet 112. As in the first embodiment, the end of the inner space 910a on the leading side coincides with the end of the first outer space 910b on the trailing side. Also, the end of the inner space 910a on the trailing side (i.e., the end opposite to the side communicating with the first outer space 910b) coincides with the second end 912 of the hole 910. Therefore, the circumferential length of the second end 912 of the hole 910 is almost the same as the widthwise length L1 of the inner space 910a. On the other hand, the circumferential length L2 of the first end 911 of the hole 910 is longer than the circumferential length L1 of the second end 912 of the hole 910. In this way, the circumferential lengths L2 and L1 of the open ends 911 and 912 of the left-right direction Ds of the hole 910 are such that the end 911 on the leading side is longer than the end 912 on the trailing side (L2>L1). Therefore, it is possible to realize the effect of increasing the torque T of the IPMSM while preventing the generation of magnetic flux 701 circulating in rotor core 111 shown in FIG. 7A. On the other hand, if the rotor core is formed only of soft magnetic material portions, the mechanical strength of rotor core 811 is reduced compared to rotor core 111 of the first embodiment. Therefore, it is preferable to provide a non-magnetic material in, for example, a part or all of the region of flux barrier 813b so that the mechanical strength of rotor core 811 is not reduced. Therefore, for example, when it is important to prevent the generation of magnetic flux 701 circulating in the rotor core, the second embodiment may be adopted, and when it is important to prevent the mechanical strength of the rotor core from being reduced, the first embodiment may be adopted. Note that the various modified examples described in the first embodiment may also be adopted in this embodiment.

[0067] (calculation example) In this calculation example, an electromagnetic field analysis of the IPMSM was performed using the finite element method when each IPMSM was operated under the following operating conditions: rotation speed = 3000 rpm, excitation current (effective value) = 5.5 A, and advance angle = 20 deg. Then, based on the magnetic flux density vector obtained as a result of the electromagnetic field analysis, a Maxwell's stress tensor was calculated, and the torque T of the IPMSM was calculated from the Maxwell's stress tensor. Hereinafter, the rotor 110 of the first embodiment will be referred to as the rotor of Example 1, and the rotor 810 of the second embodiment will be referred to as the rotor of Example 2.

[0068] FIG. 11 is a diagram showing the configuration of a rotor 1100 of Comparative Example 1. FIG. 11 is a cross-sectional view of the rotor 1100 taken perpendicularly to the center line O of the rotor 1100, and corresponds to FIG. 2. The shape of the rotor cross section is the shape shown in FIG. 11 at any position in the z-axis direction of the rotor 1100. As in the first and second embodiments, Comparative Example 1 also illustrates a case in which the number of poles of the IPMSM is four. As in the case of FIG. 2, in FIG. 11, to avoid complicating the notation, only a portion constituting one pole of the rotor 1100 is given a reference symbol, and the reference symbols of the other three poles of the rotor 1100 are omitted. As shown in FIG. 11, in the rotor 1100 of Comparative Example 1, in the cross section of the rotor core, neither a first end 1111 of a hole in which a permanent magnet 112 is installed nor a second end 1112 of a hole in which a permanent magnet 112 is installed is open.

[0069] FIG. 12 is a diagram showing the configuration of rotor 1200 of comparative example 2. FIG. 12 is a cross-sectional view of rotor 1200 taken perpendicularly to center line O of rotor 1200, and corresponds to FIG. 2. The shape of the rotor cross section is the shape shown in FIG. 12 at any position in the z-axis direction of rotor 1200. As in the first and second embodiments, comparative example 2 also illustrates a case in which the IPMSM has four poles. As in the case of FIG. 2, in FIG. 12, to avoid complicating the notation, reference numerals are attached only to the portion constituting one pole of rotor 1200, and reference numerals are omitted for the portions constituting the other three poles of rotor 1200. As shown in FIG. 12, comparative example 2 In the rotor 1200, both a first end 1211 of the hole in which the permanent magnet 112 is installed and a second end 1212 of the hole in which the permanent magnet 112 is installed are open in a cross section of the rotor core. However, the circumferential length of the first end 1211 of the hole in which the permanent magnet 112 is installed and the circumferential length of the second end 1212 of the hole in which the permanent magnet 112 is installed are the same (approximately the same as the length L1 corresponding to the length in the magnetization direction Dm of the permanent magnet 112).

[0070] When rotor 1100 of Comparative Example 1 shown in Fig. 11 was used, the torque T of the IPMSM was 0.800 Nm. In contrast, when rotor 110 of Example 1 shown in Fig. 2 was used, the torque T of the IPMSM was 1.199 Nm. In this way, the torque T of the IPMSM in Example 1 increased by 49.9% compared to Comparative Example 1. Therefore, it can be seen that the torque T of the IPMSM can be increased by forming first outer space 310b on the leading side of hole 310 in the left-right direction Ds, as shown in Fig. 3.

[0071] Furthermore, when rotor 1200 of Comparative Example 2 shown in Fig. 12 was used, the torque T of the IPMSM was 0.956 Nm. In contrast to this, when rotor 810 of Example 2 shown in Fig. 8 was used, the torque T of the IPMSM was 1.251 Nm. In this way, the torque T of the IPMSM in Example 2 increased by 30.8% compared to Comparative Example 2. Therefore, it can be seen that the torque T of the IPMSM can be increased by forming first outer space 910b on the leading side of hole 910 in the left-right direction Ds, as shown in Fig. 9.

[0072] Furthermore, comparing Example 1 with Comparative Example 1, the increase in torque caused by forming first outer space 310b on the leading side of hole 310 in the left-right direction Ds is 0.399 (=1.199-0.800) Nm. Comparing Example 1 with Example 2, the increase in torque caused by connecting second end 912 of hole 910 to the outer peripheral surface of rotor core 811 is 0.052 (1.251-1.199) Nm. Therefore, it can be seen that by forming first outer space 310b on the leading side of hole 310 in the left-right direction Ds, it is possible to effectively increase torque T of the IPMSM.

[0073] (Modification) In the first and second embodiments, the rotor core cross-sectional shape is shown in Fig. 2 and Fig. 8 at all positions in the z-axis direction of the rotor 110, 810. However, this is not necessarily required. For example, as long as the torque of the IPMSM is increased overall compared to a case in which the rotor 110, 810 does not have the shape shown in Fig. 2 and Fig. 8 at all positions in the z-axis direction of the rotor 110, 810, the rotor cross-sectional shape does not have to be the shape shown in Fig. 2 and Fig. 8 at some positions in the z-axis direction of the rotor 110, 810. For example, the rotor cross-sectional shape may be the shape shown in Fig. 11 or 12 at some positions in the z-axis direction of the rotor 110.

[0074] In the first and second embodiments, a single pole is formed by one permanent magnet 112, but the present disclosure is not limited to this. A single pole may be formed by a plurality of permanent magnets 112.

[0075] In the first and second embodiments, the case where the IPMSM 100 is an inner rotor type has been exemplified. However, the first and second ends of the hole in which the permanent magnet 112 is installed may be formed in the rotor of an outer rotor type IPMSM motor as described in the first and second embodiments. In this case, the inner circumferential surface of the rotor core becomes an end surface that faces the stator with a gap therebetween. Also, the first and second ends of the hole in which the permanent magnet 112 is installed may be formed in the rotor of a permanent magnet embedded generator instead of a permanent magnet embedded motor as described in the first and second embodiments.

[0076] In addition, in one rotor core cross section, the second end of the hole in which the permanent magnet is installed may include both a non-open end as in the first embodiment, and an end whose circumferential length is shorter than the circumferential length of the open end of the first end of the hole as in the second embodiment.

[0077] It should be noted that the above-described embodiments of the present disclosure are merely examples of specific implementations of the present disclosure, and the technical scope of the present disclosure should not be interpreted as being limited by these. In other words, the present disclosure can be implemented in various forms without departing from its technical concept or main features.

[0078] The following supplementary notes are further disclosed regarding the above embodiment.

[0079] (Appendix 1) A plurality of holes in which permanent magnets are disposed, In a cross section perpendicular to a rotation axis that is the center of rotation, at least one of the plurality of holes includes a first end portion located at the leading end of the rotation direction in a left-right direction that is a direction on both the left and right sides of the magnetization direction of the permanent magnet, and a second end portion located at the trailing end of the rotation direction in the left-right direction, The first end is open; A rotor core, wherein in the cross section, a circumferential length of the opening is longer than a circumferential length of the second end.

[0080] (Appendix 2) 2. The rotor core of claim 1, wherein, in the cross section, the circumferential length of the opening is longer than the length of the area of ​​the hole occupied by the permanent magnet in the magnetization direction of the permanent magnet.

[0081] (Appendix 3) 3. The rotor core of claim 1 or 2, wherein, in the cross-section, the first ends of all of the holes are open.

[0082] (Appendix 4) 4. The rotor core according to claim 1, wherein, in the cross section, the second end of at least one of the holes is not open.

[0083] (Appendix 5) 5. The rotor core according to claim 1, wherein the second ends of all the holes are not open in the cross section.

[0084] (Appendix 6) In the cross section, the hole with the first end open is An inner space having a width direction length equivalent to a length corresponding to a magnetization direction length of the permanent magnet; a first outer space that is in communication with the inner space, has the first end as one of the left and right ends of the hole, and is wider than the inner space; The rotor core of any one of appendix 1 to appendix 5, wherein the first end portion is positioned so as to be biased toward the rear side in the direction of rotation with respect to a circumferential center position of the inner space at a position communicating with the first outer space.

[0085] (Appendix 7) In the cross section, a circumferential length in a direction toward the rear side in the rotation direction from an extrapolated position of a rear end point of the inner space to an end point of the first end portion that is on the rear side in the rotation direction is equal to or greater than a width direction length of the inner space, The rotor core of Appendix 6, wherein the extrapolated position of the aft end point of the inner space is a position of an intersection between a straight line extending along a radial direction of the rotor core from an end point on the aft side of the inner space at a position communicating with the first outer space, and the first end, in the cross section.

[0086] (Appendix 8) A rotor core according to any one of appendix 1 to appendix 7; The permanent magnet; A rotor comprising:

[0087] (Appendix 9) A rotor according to Appendix 8; A stator; A rotating electric machine comprising:

[0088] (Appendix 10) A plurality of holes in which permanent magnets are disposed, In a cross section perpendicular to a rotation axis that is the center of rotation, at least one of the plurality of holes includes a first end portion located at the leading end of the rotation direction in a left-right direction that is a direction on both the left and right sides of the magnetization direction of the permanent magnet, and a second end portion located at the trailing end of the rotation direction in the left-right direction, the first end portion is open to an outer circumferential surface, and a circumferential length of the opening is longer than a circumferential length of the second end portion; In the cross section, the hole with the first end opening has an inner space whose widthwise length is equal to a length corresponding to a length in the magnetization direction of the permanent magnet, and a first outer space that communicates with the inner space, has the first end as one of the left and right ends of the hole, and is wider than the inner space, A rotor core, wherein the first end portion is positioned so as to be biased toward the rear side in the direction of rotation with respect to a circumferential center position of the inner space at a position where the inner space communicates with the first outer space.

[0089] (Appendix 11) In the cross section, a circumferential length in a direction toward the rear side in the rotation direction from an extrapolated position of a rear end point of the inner space to an end point of the first end portion that is on the rear side in the rotation direction is equal to or greater than a width direction length of the inner space, A rotor core according to claim 10, wherein an extrapolated position of a rear end point of the inner space is a position of an intersection between a straight line extending along a radial direction of the rotor core from an end point on a rear side of the inner space at a position communicating with the first outer space, and the first end, in the cross section.

[0090] (Appendix 12) 12. The rotor core of claim 10, wherein a rear wall surface forming a rear side of the first outer space in the rotational direction is inclined with respect to a direction perpendicular to the rotation axis in a hole wall surface that constitutes the hole.

[0091] (Appendix 13) 13. The rotor core of claim 11 or 12, wherein at least a portion of the aft wall surface is concavely curved.

[0092] (Appendix 14) 14. The rotor core of claim 10, wherein, in the cross section, the circumferential length of the opening is longer than the length of the region of the hole occupied by the permanent magnet in the magnetization direction of the permanent magnet.

[0093] (Appendix 15) 15. The rotor core according to any one of claims 10 to 14, wherein the first ends of all of the holes are open in the cross section.

[0094] (Appendix 16) 16. The rotor core according to any one of claims 10 to 15, wherein, in the cross section, the second end of at least one of the holes is not open. (Appendix 17) 17. The rotor core according to any one of claims 10 to 16, wherein, in the cross section, the second ends of all the holes are not open.

[0095] (Appendix 18) A rotor core according to any one of appendix 10 to appendix 17, The permanent magnet; A rotor comprising:

[0096] (Appendix 19) A rotor according to claim 18; A rotating electric machine comprising: a stator.

[0097] The disclosure of Japanese Patent Application No. 2021-060596, filed on March 31, 2021, is incorporated by reference in its entirety into this specification. All publications, patent applications, and standards mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent application, or standard was specifically and individually indicated to be incorporated by reference.

Claims

1. A plurality of holes in which permanent magnets are disposed, In a cross section perpendicular to a rotation axis that is a center of rotation, at least one of the plurality of holes includes a first end portion located at a leading end of a rotation direction in a left-right direction that is a direction on both the left and right sides of a magnetization direction of the permanent magnet, and a second end portion located at a trailing end of the rotation direction in the left-right direction, The first end portion is open to an outer circumferential surface, and a circumferential length of the opening is longer than a circumferential length of the second end portion. In the cross section, the hole with the first end opening has an inner space whose widthwise length is equal to a length corresponding to a length in the magnetization direction of the permanent magnet, and a first outer space that communicates with the inner space, has the first end as one of the left and right ends of the hole, and is wider than the inner space, the first end portion is disposed so as to be biased toward a rear side in a rotation direction with respect to a circumferential center position of the inner space at a position where the inner space communicates with the first outer space, In the cross section, a circumferential length in a direction toward the rear side in the rotation direction from an extrapolated position of a rear end point of the inner space to an end point of the first end portion, the end point being located on the rear side in the rotation direction, is equal to or greater than a width direction length of the inner space, a rotor core, wherein the extrapolated position of the rear end point of the inner space is the position of the intersection, in the cross section, of a straight line extending from the rear end point of the inner space at a position communicating with the first outer space along the radial direction of the rotor core and the first end.

2. The rotor core according to claim 1 , wherein a rear wall surface forming a rear side of the first outer space in the rotational direction is inclined with respect to a direction perpendicular to the rotation axis in a hole wall surface that constitutes the hole.

3. The rotor core according to claim 2 , wherein at least a portion of the aft wall surface is concavely curved.

4. A rotor core according to any one of claims 1 to 3, wherein in the cross section, the circumferential length of the opening is longer than the length of the area of ​​the hole occupied by the permanent magnet in the magnetization direction of the permanent magnet.

5. The rotor core according to any one of claims 1 to 4, wherein the first ends of all of the holes are open in the cross section.

6. The rotor core according to any one of claims 1 to 5, wherein in the cross section, at least one of the holes does not open at the second end.

7. The rotor core according to any one of claims 1 to 6, wherein the second ends of all the holes are not open in the cross section.

8. A rotor core according to any one of claims 1 to 7, The permanent magnet; A rotor comprising:

9. A rotor according to claim 8; A rotating electric machine comprising: a stator.

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