JP7112340B2 - Rotor of rotating electric machine and rotating electric machine - Google Patents

Description

The present invention relates to a rotor of a rotating electrical machine and a rotating electrical machine.

2. Description of the Related Art In a rotating electric machine mounted on a hybrid vehicle, an electric vehicle, or the like, a magnetic field is formed in a stator core by supplying current to a coil, and magnetic attraction and repulsion are generated between the magnets of the rotor and the stator core. This causes the rotor to rotate relative to the stator.

As a rotor used in a rotating electric machine, a so-called IPM (Interior Permanent Magnet) is known, in which magnets (for example, permanent magnets) are embedded in each of a plurality of magnet insertion holes inside the rotor core when viewed from the axial direction of the rotor core. It is For example, Patent Literature 1 discloses a structure in which a gap is formed in the rotor core so as to cover the corners of the magnets inserted into the magnet insertion holes in order to prevent demagnetization of the magnets in the IPM motor. ing.

Japanese Patent No. 5930409

However, if a gap is formed in the rotor core so as to cover the corners of the magnets inserted into the magnet insertion holes, there is a possibility that the portion of the magnets through which the magnetic flux passes will increase and the back electromotive force will increase.
Therefore, there is room for improvement in reducing the back electromotive force while suppressing demagnetization of the magnet.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a rotor of a rotating electrical machine and a rotating electrical machine that can reduce back electromotive force while suppressing demagnetization of magnets.

(1) A rotor (eg, the rotor 4 in the embodiment) of a rotating electrical machine (eg, the rotating electrical machine 1 in the embodiment) according to one aspect of the present invention has a plurality of magnet insertion holes (eg, the magnet insertion holes 25 in the embodiment). ) and magnets embedded in the magnet insertion holes (for example, the magnets 22 in the embodiment), and when viewed from the axial direction of the rotor core, the plurality of An IPM in which magnet insertion holes are formed at intervals in the circumferential direction of the rotor core, and the magnets are embedded in each of the plurality of magnet insertion holes inside the rotor core, wherein the magnet insertion holes A magnet insertion portion into which a magnet is inserted (for example, the magnet insertion portion 26 in the embodiment), and a gap adjacent to the magnet insertion portion and into which resin is injected while the magnet is inserted into the magnet insertion portion (for example, , a gap portion 30 in the embodiment), and when viewed from the axial direction, the gap portion is adjacent to a magnetic flux passage surface (for example, the magnetic flux passage surface 22a in the embodiment) of the magnet through which the magnetic flux passes. A first gap (for example, the first gap 31 in the embodiment) formed to cover a surface (for example, the adjacent surface 22b in the embodiment) communicates with the first gap, and the magnetic flux passing surface of the magnet is and a second air gap (for example, the second air gap 32 in the embodiment) formed so as to cover the second air gap. It gradually increases from a strong portion (for example, the maximum magnetic flux Mp in the embodiment) toward the end of the magnet (for example, the end E1 of the magnet in the embodiment), and the portion where the magnetic flux is the strongest is the axis It is the central portion in the longitudinal direction of the magnet, which is rectangular when viewed from the direction .
(2) In one aspect of the present invention, the rotor core includes a convex portion (for example, the convex portion 40 in the embodiment) for positioning and fixing the magnet, and the second gap is provided with the convex portion through the magnet. You may arrange|position facing the part.
(3) In one aspect of the present invention, the second gap may be arranged closer to the outer periphery of the rotor core than the magnets.
(4) In one aspect of the present invention, the rotor core includes a first wall forming the first gap (for example, the first wall 41 in the embodiment) and a second wall forming the second gap (for example, and the second wall 42) in the embodiment, and when viewed from the axial direction, the second wall extends from the portion facing the strongest magnetic flux on the magnetic flux passing surface of the magnet to the first wall. It may be continuous while curving toward it.
(5) In one aspect of the present invention, the plurality of magnet insertion holes may be arranged in a V shape when viewed from the axial direction.
(6) In one aspect of the present invention, when viewed from the axial direction, the second gap gradually increases from a portion where magnetic flux is strongest on the magnetic flux passing surface of the magnet toward both ends of the magnet. good too.
(7) In one aspect of the present invention, when viewed from the axial direction, the second gap is a virtual straight line (for example, the virtual straight line K1 in the embodiment) along the direction of the strongest magnetic flux on the magnetic flux passing surface of the magnet. may have a symmetrical shape with the axis of symmetry.
(8) A rotary electric machine according to an aspect of the present invention includes an annular stator (for example, the stator 3 in the embodiment) and the above-described rotor arranged radially inside the stator.

According to the above aspect (1), when viewed from the axial direction, the air gap portion communicates with the first air gap formed so as to cover the surface adjacent to the magnetic flux passing surface through which the magnetic flux passes in the magnet, and the first air gap. and a second gap formed so as to cover the magnetic flux passing surface of the magnet. By covering the corners of the magnet where demagnetization is likely to occur with the gap, demagnetization of the magnet can be suppressed. can. In addition, when viewed from the axial direction, the second gap gradually increases from the area where the magnetic flux is strongest on the magnetic flux passage surface of the magnet toward the end of the magnet, so that the magnet inserted into the magnet insertion hole is Compared to the case where the gap is formed in the rotor core so as to cover only the periphery of the corners, the portion of the magnet through which the magnetic flux passes becomes as small as possible, so that the back electromotive force can be reduced. Therefore, it is possible to reduce the back electromotive force while suppressing demagnetization of the magnet.
According to the above aspect (2), the rotor core includes the convex portion for positioning and fixing the magnet, and the second gap is arranged to face the convex portion through the magnet. When the resin is injected, the resin presses the magnet against the convex portion, so the magnet can be positioned.
According to the above aspect (3), the second air gap is arranged on the outer peripheral side of the rotor core relative to the magnets, so that the corners of the magnets closest to the stator (the corners of the magnets that are attenuated by the reverse magnetic field from the stator, etc.) Since the corners where magnetism is likely to occur are covered with air gaps, demagnetization of the magnets can be further suppressed.
According to the aspect (4) above, the rotor core has a first wall that forms the first gap and a second wall that forms the second gap, and when viewed in the axial direction, the second wall: Concentration of stress on the second wall can be suppressed by curving and continuing from the portion facing the strongest portion of the magnetic flux passage surface of the magnet toward the first wall.
According to the above aspect (5), the plurality of magnet insertion holes are arranged in a V shape when viewed from the axial direction. can be reduced while suppressing the back electromotive voltage.
According to the aspect (6) above, when viewed from the axial direction, the second gap gradually increases from the portion where the magnetic flux is strongest on the magnetic flux passing surface of the magnet toward both end portions of the magnet. Effective. Compared to the case where the second gap gradually increases toward only one end of the magnet from the area where the magnetic flux is strongest on the magnetic flux passage surface of the magnet, the area through which the magnetic flux passes becomes smaller in the magnet, resulting in a back electromotive force. can be further reduced.
According to the above aspect (7), when viewed from the axial direction, the second gap has a line-symmetrical shape with an imaginary straight line along the direction of the strongest magnetic flux on the magnetic flux passing surface of the magnet as an axis of symmetry. It is possible to maintain the balance of magnetic flux between the one end side and the other end side.
According to the above aspect (8), by including the annular stator and the rotor arranged radially inward with respect to the stator, counter electromotive force is reduced while suppressing demagnetization of the magnet. It is possible to provide a rotating electric machine that can

1 is a schematic configuration diagram of a rotary electric machine according to an embodiment; FIG. The II arrow directional view of FIG. 1 which looked at the rotor which concerns on embodiment from the axial direction. FIG. 3 is an enlarged view of a main portion of FIG. 2, when the rotor according to the embodiment is viewed from the axial direction; FIG. 4 is an enlarged view of a main part of FIG. 3, when the second gap according to the embodiment is viewed from the axial direction; FIG. 4 is an enlarged view of a main portion corresponding to FIG. 3, when a rotor according to a comparative example is viewed from the axial direction; Explanatory drawing of the magnetic flux amount of the magnet which concerns on an Example. FIG. 5 is an explanatory diagram of the amount of magnetic flux of a magnet according to Comparative Example 1; FIG. 9 is an explanatory diagram of the amount of magnetic flux of a magnet according to Comparative Example 2; FIG. 4 is a contour diagram showing the demagnetization characteristics of the magnet according to the example. 4 is a contour diagram showing demagnetization characteristics of a magnet according to Comparative Example 1. FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the embodiments, a rotary electric machine (running motor) mounted on a vehicle such as a hybrid vehicle or an electric vehicle will be described.

<Rotating electric machine>
FIG. 1 is a schematic configuration diagram showing the overall configuration of a rotating electric machine 1 according to an embodiment. FIG. 1 is a diagram including a cross-section taken along an imaginary plane containing the axis C. FIG.
As shown in FIG. 1 , the rotating electric machine 1 includes a case 2 , a stator 3 , a rotor 4 and a shaft 5 .

The case 2 has a cylindrical box shape that accommodates the stator 3 and the rotor 4 . A refrigerant (not shown) is accommodated in the case 2 . A portion of the stator 3 is immersed in the coolant inside the case 2 . For example, as the refrigerant, ATF (Automatic Transmission Fluid) or the like, which is hydraulic oil used for lubrication of a transmission, power transmission, or the like, is used.

Shaft 5 is rotatably supported by case 2 . Reference numeral 6 in FIG. 1 denotes a bearing that rotatably supports the shaft 5 . Hereinafter, the direction along the axis C of the shaft 5 will be referred to as the "axial direction", the direction orthogonal to the axis C will be referred to as the "radial direction", and the direction around the axis C will be referred to as the "circumferential direction".

The stator 3 includes a stator core 11 and multiple layers (for example, U-phase, V-phase, and W-phase) coils 12 attached to the stator core 11 .
The stator core 11 has an annular shape coaxial with the axis C. As shown in FIG. Stator core 11 is fixed to the inner peripheral surface of case 2 . For example, the stator core 11 is formed by laminating a plurality of electromagnetic steel sheets (silicon steel sheets) in the axial direction. In addition, the stator core 11 may be a so-called powder core obtained by compression-molding metal magnetic powder (soft magnetic powder).

Stator core 11 has slots 13 into which coils 12 are inserted. A plurality of slots 13 are arranged at intervals in the circumferential direction. The coil 12 includes insertion portions 12 a inserted through the slots 13 of the stator core 11 and coil end portions 12 b projecting axially from the stator core 11 . Stator core 11 generates a magnetic field when current flows through coil 12 .

<Rotor>
The rotor 4 is arranged radially inside the stator 3 with a space therebetween. A rotor 4 is fixed to the shaft 5 . The rotor 4 is configured to be rotatable around the axis C integrally with the shaft 5 . The rotor 4 includes a rotor core 21 , magnets 22 and end plates 23 . For example, magnet 22 is a permanent magnet.

The rotor core 21 has an annular shape coaxial with the axis C. As shown in FIG. The rotor core 21 has a shaft fixing hole 8 into which the shaft 5 is press-fitted and fixed on the radially inner side. The rotor core 21 is formed by laminating a plurality of electromagnetic steel sheets (silicon steel sheets) in the axial direction. It should be noted that the rotor core 21 may be a so-called dust core obtained by compression-molding metal magnetic powder (soft magnetic powder).

The end plates 23 are arranged at both ends of the rotor core 21 in the axial direction. The end plates 23 cover at least the magnet insertion holes 25 in the rotor core 21 from both axial end sides. The end plate 23 is in contact with the axial outer end surface of the rotor core 21 .

The rotor core 21 has a plurality of magnet insertion holes 25 axially penetrating the rotor core 21 . The plurality of magnet insertion holes 25 are arranged at intervals in the circumferential direction on the outer peripheral portion of the rotor core 21 . A magnet 22 is embedded in each magnet insertion hole 25 .

FIG. 2 is a view of the rotor 4 according to the embodiment viewed from the axial direction, taken along arrow II in FIG. In FIG. 2, illustration of the shaft 5 and the end plate 23 is omitted.
When viewed from the axial direction, the plurality of magnet insertion holes 25 are arranged in a V shape. Specifically, when viewed from the axial direction, two magnet insertion holes 25 adjacent in the circumferential direction are V-shaped and open radially outward. When viewed in the axial direction, two magnets 22 adjacent in the circumferential direction form a V shape that opens radially outward.

In the figure, reference numeral 51 denotes a first hole group having a plurality of first holes arranged in the inner peripheral portion of the rotor core 21, 4A and 4B each show a second hole group having a plurality of second holes. This contributes to weight reduction of the rotor core 21 .

The magnet 22 has a rectangular parallelepiped shape having a rectangular cross-sectional shape perpendicular to the axial direction. The magnet 22 has a magnetic flux passage surface 22a through which the magnetic flux passes and an adjacent surface 22b adjacent to the magnetic flux passage surface 22a. The magnets 22 are embedded in each of the plurality of magnet insertion holes 25 inside the rotor core 21 . The rotor core 21 has projections 40 for positioning and fixing the magnets 22 . The protrusions 40 are arranged inside the rotor core 21 so as to face each of the plurality of magnet insertion holes 25 . In the figure, reference numeral 45 denotes a pair of projections facing each other across the projection 40, and reference numeral 46 denotes a pair of through holes formed between the pair of projections 45 and the projection 40 to relieve stress concentration. respectively.

The rotor 4 of this embodiment is an IPM in which the magnets 22 are embedded in each of the plurality of magnet insertion holes 25 inside the rotor core 21 . In this embodiment, a plurality of pairs (eight pairs in the example of FIG. 2) of a pair of magnet insertion holes 25 arranged in a V shape when viewed from the axial direction are arranged at substantially equal intervals in the circumferential direction. That is, the plurality of pairs of magnet insertion holes 25 are arranged in the outer peripheral portion of the rotor core 21 at intervals of substantially 45° in the circumferential direction.

In this embodiment, a plurality of pairs (eight pairs in the example of FIG. 2) of a pair of magnets 22 arranged in a V shape when viewed from the axial direction are arranged at substantially equal intervals in the circumferential direction. That is, the plurality of pairs of magnets 22 are arranged on the outer peripheral portion of the rotor core 21 at intervals of substantially 45° in the circumferential direction. Each pair of magnets 22 has the same polarity (N pole or S pole) on surfaces facing each other in the circumferential direction. Each pair of magnets 22 is magnetized such that the polarities of the magnetic poles formed by the magnets 22 on the outer peripheral surface of the rotor core 21 (the portion of the rotor core 21 sandwiched between the pair of magnets 22) are alternately arranged in the circumferential direction. In FIG. 2, the arrow Vd indicates the d-axis direction of the magnetic pole formed by the magnet 22, and the arrow Vq indicates the q-axis direction.

<Structure of Rotor Core>
FIG. 3 is an enlarged view of a main portion of FIG. 2, when the rotor 4 according to the embodiment is seen from the axial direction. In FIG. 3, Ld denotes the d-axis of the magnetic pole formed by the magnet 22, and Lq denotes the q-axis. When viewed from the axial direction, the d-axis Ld corresponds to an imaginary straight line (an imaginary straight line passing through the magnetic pole center) that passes through the axis C and bisects the pair of V-shaped magnets 22 . When viewed from the axial direction, the q-axis Lq corresponds to an imaginary straight line (an imaginary straight line passing through the center between the magnetic poles) that passes through the axis C and bisects the two pairs of magnets 22 that are adjacent in the circumferential direction.

As shown in FIG. 3 , the magnet insertion hole 25 has a magnet insertion portion 26 into which the magnet 22 is inserted, and a gap portion 30 adjacent to the magnet insertion portion 26 .
The magnet inserting portion 26 is a gap having the same outer shape as the magnet 22 in the magnet inserting hole 25 . When viewed from the axial direction, the magnet insertion portion 26 is a portion overlapping the magnet 22 in the magnet insertion hole 25 .
The gap portion 30 is a portion into which resin is injected while the magnet 22 is inserted into the magnet insertion portion 26 . When viewed from the axial direction, the gap 30 is a portion of the magnet insertion hole 25 that does not overlap the magnet 22 (a portion that avoids the magnet 22).

When viewed from the axial direction, the air gap portion 30 communicates with a first air gap 31 formed to cover the adjacent surface 22b of the magnet 22 and is formed to cover the magnetic flux passing surface 22a of the magnet 22. and a second void 32 .

The first gap 31 is formed so as to cover each of the pair of adjacent surfaces 22b of the magnet 22 adjacent to the magnetic flux passing surface 22a. The second gap 32 is arranged closer to the outer circumference of the rotor core 21 than the magnets 22 are. The air gap 30 is formed so as to cover corners E1 and E2 formed by the magnetic flux passing surface 22a and the adjacent surface 22b of the magnet 22 by connecting the first air gap 31 and the second air gap 32. . The air gap 30 covers two corners E1 and E2 located on the outer peripheral side of the rotor core 21 among the four corners.

When viewed from the axial direction, the second air gap 32 gradually increases from a portion Mp where the magnetic flux is strongest on the magnetic flux passage surface 22a of the magnet 22 (hereinafter also referred to as “maximum magnetic flux portion Mp”) toward the end of the magnet 22. ing. Here, the maximum magnetic flux portion Mp means the central portion in the longitudinal direction of the magnet 22 which has a rectangular shape when viewed from the axial direction. The end of the magnet 22 means the longitudinal end of the magnet, which is rectangular when viewed from the axial direction.

When viewed from the axial direction, the second air gap 32 gradually increases from the magnetic flux maximum Mp of the magnet 22 toward both ends (two corners E1 and E2 located on the outer peripheral side of the rotor core 21 in the embodiment). . When viewed from the axial direction, the second air gap 32 has a line-symmetrical shape with an imaginary straight line K1 along the direction of the strongest magnetic flux on the magnetic flux passing surface 22a of the magnet 22 as an axis of symmetry (see FIG. 4).

The second gap 32 is arranged to face the protrusion 40 with the magnet 22 interposed therebetween. When viewed from the axial direction, the convex portion 40 has a line-symmetrical shape with the imaginary straight line K1 as an axis of symmetry. The protrusion 40 has a contact surface 40 a that contacts the surface of the magnet 22 opposite to the second gap 32 .

The rotor core 21 has a first wall 41 forming a first gap 31 and a second wall 42 forming a second gap 32 . When viewed from the axial direction, the second wall 42 continues while curving toward the first wall 41 from a portion of the magnet 22 that faces the maximum magnetic flux portion Mp.

As shown in FIG. 4 , the second wall 42 has a curved shape that protrudes toward the magnet 22 at a portion facing the maximum magnetic flux portion Mp of the magnet 22 . When viewed from the axial direction, the second gap 32 extends from the maximum magnetic flux portion Mp of the magnet 22 to both ends (located on the outer peripheral side of the rotor core 21 in the embodiment) between the magnetic flux passage surface 22a of the magnet 22 and the second wall 42. It has a gradually increasing gap toward the two corners E1, E2). The second air gap 32 has a minimum gap S1 at the magnetic flux maximum Mp of the magnet 22 . The second air gap 32 has a maximum gap S2 at the ends of the magnets 22 .

<Effect>
Next, the effect of the rotor 4 of this embodiment is demonstrated.
First, the rotor 4X of a comparative example is demonstrated. FIG. 5 is an enlarged view of a main portion corresponding to FIG. 3, when the rotor 4X according to the comparative example is seen from the axial direction. In FIG. 5, reference numeral 22X denotes a magnet, reference numeral 25X denotes a magnet slot for inserting the magnet 22X, and reference numeral 31X denotes a flux barrier for suppressing leakage magnetic flux.

As shown in FIG. 5, the magnet slot 25X is formed slightly larger than the thickness of the magnet 22X. In general, the magnetic force of the magnet 22X is maximized by reducing the gap SX in the thickness direction of the magnet 22X in the magnet slot 25X. On the other hand, if the gap SX is made too small, the following problems will occur.
(1) As the magnetic flux of the magnet increases, the back electromotive force increases.
(2) Iron loss increases as the magnetic flux of the magnet increases.
(3) Demagnetization tends to occur at the ends of the magnet.
(4) It is difficult to inject resin into the magnet slots to fix the magnets.
In order to reduce the back electromotive voltage and reduce iron loss, it is conceivable to increase the flux barrier 31X. However, if the flux barrier 31X is made too large, the d-axis inductance and the q-axis inductance will decrease, and there is a high possibility that the reluctance torque will decrease.

On the other hand, the rotor 4 of this embodiment has a structure in which the gap at the maximum magnetic flux portion Mp of the magnet 22 in the magnet insertion hole 25 is the smallest, and the gap gradually increases toward both ends of the magnet 22 (Fig. 3). reference). According to this configuration, the d-axis magnetic resistance is greater than in the comparative example, so the reluctance torque does not decrease and the magnetic flux of the magnet 22 decreases. As a result, the back electromotive force can be reduced, and iron loss can be reduced. In the present embodiment, the magnetic flux of the magnet 22 is reduced by 13% compared to the comparative example, and the back electromotive voltage under no-load conditions is accordingly reduced. In this embodiment, the iron loss under no-load conditions is expected to be reduced by 23% compared to the comparative example.
In addition, in this embodiment, since the end of the magnet 22 is covered with the largest gap in the magnet insertion hole 25, demagnetization of the end of the magnet 22 can be suppressed.
Furthermore, in the present embodiment, the resin flows from both ends (maximum gap S2) of the magnet 22 toward the center (minimum gap S1) of the magnet 22 during resin injection, so that the resin can be injected more easily than in the comparative example.

As described above, the rotor 4 of the rotary electric machine 1 of the above embodiment includes the rotor core 21 having a plurality of magnet insertion holes 25 and the magnets 22 embedded in the magnet insertion holes 25. When viewed from above, a plurality of magnet insertion holes 25 are formed at intervals in the circumferential direction of the rotor core 21, and the magnets 22 are IPMs embedded in the plurality of magnet insertion holes 25 inside the rotor core 21, The magnet insertion hole 25 has a magnet insertion portion 26 into which the magnet 22 is inserted, and a gap portion 30 adjacent to the magnet insertion portion 26 and into which resin is injected while the magnet 22 is inserted into the magnet insertion portion 26 . When viewed from the axial direction, the air gap portion 30 communicates with a first air gap 31 formed so as to cover an adjacent surface 22b adjacent to the magnetic flux passing surface 22a through which the magnetic flux passes in the magnet 22, and the first air gap 31, and a second gap 32 formed to cover the magnetic flux passing surface 22a of the magnet 22. When viewed from the axial direction, the second gap 32 extends from the maximum magnetic flux Mp of the magnet 22 to the end of the magnet 22. gradually increasing in size.
According to this configuration, when viewed from the axial direction, the air gap portion 30 includes the first air gap 31 formed so as to cover the adjacent surface 22b adjacent to the magnetic flux passing surface 22a through which the magnetic flux passes in the magnet 22, and the first air gap 31 and a second air gap 32 formed to cover the magnetic flux passing surface 22a of the magnet 22. By covering the corners of the magnet 22 where demagnetization is likely to occur with the air gap 30, the magnet 22 demagnetization can be suppressed. In addition, when viewed from the axial direction, the second air gap 32 gradually increases from the magnetic flux maximum Mp of the magnet 22 toward the end of the magnet 22, so that the magnet 22 inserted into the magnet insertion hole 25 is Compared to the case where the gap is formed in the rotor core 21 so as to cover only the periphery of the corners, the area through which the magnetic flux passes in the magnets 22 becomes as small as possible, so the back electromotive force can be reduced. Therefore, the back electromotive force can be reduced while suppressing demagnetization of the magnet 22 .

In the above-described embodiment, the rotor core 21 has the convex portion 40 for positioning and fixing the magnet 22, and the second gap 32 is arranged to face the convex portion 40 with the magnet 22 interposed therebetween. Since the magnets 22 are pressed against the projections 40 by the resin when the resin is injected into the magnets 30, the magnets 22 can be positioned.

In the above-described embodiment, the second air gap 32 is arranged closer to the outer circumference of the rotor core 21 than the magnets 22 , so that the corners of the magnets 22 closest to the stator 3 (the magnets 22 are Since the corner portion where demagnetization is likely to occur at the edge) is covered with the air gap portion 30, the demagnetization of the magnet 22 can be further suppressed.

In the above embodiment, the rotor core 21 has the first wall 41 forming the first gap 31 and the second wall 42 forming the second gap 32. When viewed from the axial direction, the second wall 42 is , the portion facing the maximum magnetic flux portion Mp of the magnet 22 continues while curving toward the first wall 41 , stress concentration on the second wall 42 can be suppressed.

In the above-described embodiment, the plurality of magnet insertion holes 25 are arranged in a V shape when viewed from the axial direction. It is possible to reduce the back electromotive voltage while

In the above-described embodiment, the second air gap 32 gradually increases from the maximum magnetic flux portion Mp of the magnet 22 toward both ends of the magnet 22 when viewed in the axial direction, thereby providing the following effects. Compared to the case where the second gap 32 gradually increases from the maximum magnetic flux portion Mp of the magnet 22 toward only one end portion of the magnet 22, the portion through which the magnetic flux passes becomes smaller in the magnet 22, so that the back electromotive force is reduced. It can be reduced even further.

In the above-described embodiment, when viewed from the axial direction, the second air gap 32 has a line-symmetrical shape with the imaginary straight line K1 along the direction of the strongest magnetic flux on the magnetic flux passing surface 22a of the magnet 22 as an axis of symmetry. It is possible to maintain the balance of magnetic flux between the one end side and the other end side.

The rotary electric machine 1 of the above embodiment includes the annular stator 3 and the rotor 4 arranged radially inwardly of the stator 3 , so that demagnetization of the magnets 22 is suppressed and the back electromotive force is generated. can be provided.

Modifications of the embodiment will be described below. In each modified example, the same components as in the embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

In the above-described embodiment, the configuration in which the second gap 32 is arranged closer to the outer circumference of the rotor core 21 than the magnet 22 is described, but the configuration is not limited to this. For example, the second gap 32 may be arranged closer to the inner circumference of the rotor core 21 than the magnets 22 are.

In the above-described embodiment, the configuration in which the second wall 42 is curved and continued from the portion facing the maximum magnetic flux portion Mp of the magnet 22 toward the first wall 41 when viewed from the axial direction has been described. It is not limited to this. For example, when viewed in the axial direction, the second wall 42 may continue linearly from the portion facing the maximum magnetic flux portion Mp of the magnet 22 toward the first wall 41 .

In the embodiment described above, the configuration in which the plurality of magnet insertion holes 25 are arranged in a V shape when viewed from the axial direction has been described, but the present invention is not limited to this. For example, the plurality of magnet insertion holes 25 may be arranged radially.

In the above-described embodiment, the second gap 32 is configured to gradually increase from the maximum magnetic flux portion Mp of the magnet 22 toward both ends of the magnet 22 when viewed in the axial direction, but the present invention is not limited to this. For example, the second air gap 32 may gradually increase from the magnetic flux maximum Mp of the magnet 22 toward only one end of the magnet 22 .

In the above-described embodiment, eight pairs of magnet insertion holes 25 arranged in a V shape when viewed from the axial direction are arranged in the rotor core 21 in the circumferential direction. is not limited to For example, the number of arranged pairs of magnet insertion holes 25 may be 7 pairs or less, or may be 9 pairs or more.

In the above-described embodiment, the rotary electric machine 1 is a running motor mounted in a vehicle such as a hybrid vehicle or an electric vehicle. However, the present invention is not limited thereto. For example, the rotating electrical machine 1 may be a motor for power generation, a motor for other purposes, or a rotating electrical machine (including a generator) other than for vehicles.

Although preferred embodiments of the present invention have been described above, the present invention is not limited to these, and additions, omissions, substitutions, and other modifications of the configuration are possible without departing from the scope of the present invention. It is also possible to appropriately combine the modifications described above.

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[Example]
The example used the rotor 4 having the second gap 32 according to the present embodiment (see FIG. 3). In the example, the maximum gap S2 of the second gap 32 (the size of the gap at the corner of the magnet 22) was set to 1.36 mm.

[Comparative Example 1]
Comparative Example 1 uses a rotor 4X having magnet slots 25X that are slightly larger than the thickness of the magnets 22X (see FIG. 5).

[Comparative Example 2]
Comparative Example 2 uses a rotor 4Y in which the gap gradually increases from a position offset from the center of the magnet toward the end (see FIG. 8). In Comparative Example 2, the size of the gap (maximum gap) at the corners of the magnet was set to 0.65 mm.

[Experimental example]
In each of Examples and Comparative Examples 1 and 2, the magnetic flux amount of the magnet was measured under no-load conditions. Also, in each of the example and comparative example 1, the demagnetization characteristics of the magnet were measured under the same current conditions.

FIG. 6 is an explanatory diagram of the amount of magnetic flux of the magnet according to the example. FIG. 7 is an explanatory diagram of the magnetic flux amount of the magnet according to Comparative Example 1. FIG. FIG. 8 is an explanatory diagram of the amount of magnetic flux of a magnet according to Comparative Example 2. FIG. In FIGS. 6 to 8, the distribution of the magnetic flux density is indicated by dot hatching, and the dot hatching becomes darker as the magnetic flux density increases in the rotor core.
As shown in FIG. 6, the number of magnetic flux lines was 18 in the example.
As shown in FIG. 7, in Comparative Example 1, the number of magnetic flux lines was 21.
As shown in FIG. 8, in Comparative Example 2, the number of magnetic flux lines was twenty.
In the example, it was confirmed that the amount of magnetic flux of the magnet was reduced more than in the comparative examples 1 and 2, respectively.

FIG. 9 is a contour diagram showing the demagnetization characteristics of the magnet according to the example. 10 is a contour diagram showing the demagnetization characteristics of the magnet according to Comparative Example 1. FIG. In FIGS. 9 and 10, the distribution of the demagnetization rate is indicated by dot hatching, and the dot hatching becomes darker as the demagnetization rate increases in the magnet.
As shown in FIG. 9, it was confirmed that in Example, the demagnetization rate at the end of the magnet was lower than in Comparative Example 1 (see FIG. 10).

DESCRIPTION OF SYMBOLS 1... Rotating electric machine 3... Stator 4... Rotor 21... Rotor core 22... Magnet 22a... Magnetic flux passage surface 22b... Adjacent surface 25... Magnet insertion hole 26... Magnet insertion part 30... Gap part 31... First gap 32... Second gap 40 ... Convex portion 41 ... First wall 42 ... Second wall C ... Axis line E1, E2 ... Corners of magnets (edges of magnets)
K1: virtual straight line Mp: maximum magnetic flux (part where the magnetic flux is the strongest)

Claims (8)

a rotor core having a plurality of magnet insertion holes;
a magnet embedded in the magnet insertion hole,
When viewed from the axial direction of the rotor core, the plurality of magnet insertion holes are formed at intervals in the circumferential direction of the rotor core, and the magnets are embedded in each of the plurality of magnet insertion holes inside the rotor core. is an IPM,
The magnet insertion hole is
a magnet insertion portion into which the magnet is inserted;
a gap adjacent to the magnet insertion portion and into which resin is injected while the magnet is inserted into the magnet insertion portion;
When viewed from the axial direction, the gap is
a first gap formed to cover an adjacent surface adjacent to the magnetic flux passage surface through which the magnetic flux passes in the magnet;
a second air gap communicating with the first air gap and formed to cover the magnetic flux passing surface of the magnet;
When viewed from the axial direction, the second gap gradually increases from a portion of the magnetic flux passing surface of the magnet where the magnetic flux is strongest toward the end of the magnet ,
A rotor for a rotary electric machine , wherein the portion where the magnetic flux is the strongest is a central portion in the longitudinal direction of the magnet, which has a rectangular shape when viewed from the axial direction . The rotor core has a protrusion for positioning and fixing the magnet,
2. The rotor of a rotary electric machine according to claim 1, wherein said second gap is arranged to face said protrusion via said magnet. 3. The rotor of a rotary electric machine according to claim 1, wherein the second gap is arranged closer to the outer circumference of the rotor core than the magnet. The rotor core is
a first wall forming the first void;
a second wall forming the second gap,
When viewed from the axial direction, the second wall is continuous while curving toward the first wall from a portion facing a portion of the magnetic flux passing surface of the magnet where the magnetic flux is strongest. The rotor of the rotary electric machine according to any one of claims 1 to 3. The rotor of a rotary electric machine according to any one of claims 1 to 4, wherein the plurality of magnet insertion holes are arranged in a V shape when viewed from the axial direction. 6. When viewed from the axial direction, the second gap gradually increases from a portion of the magnetic flux passage surface of the magnet where the magnetic flux is strongest toward both end portions of the magnet. The rotor of the rotary electric machine according to any one of 1. 7. The method according to claim 6, wherein when viewed from the axial direction, the second air gap has a symmetrical shape with an imaginary straight line along the direction of the strongest magnetic flux on the magnetic flux passing surface of the magnet as an axis of symmetry. Rotor of rotary electric machine. an annular stator;
A rotary electric machine, comprising: a rotor according to any one of claims 1 to 7 arranged radially inside the stator.

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