JP7489284B2 - Rotating Electric Machine - Google Patents

Description

The present invention relates to a rotating electric machine and a rotor.

Conventionally, embedded magnet type rotating electric machines have been known that have a rotor in which multiple magnet insertion holes are provided in the rotor core and multiple permanent magnets are embedded in the rotor core (e.g., Patent Document 1).

Patent 6452841

In embedded magnet type rotating electric machines, multiple permanent magnets are embedded evenly in the rotor core in the circumferential direction of the rotor core, so each of the multiple magnet insertion holes is evenly spaced in the circumferential direction of the rotor and penetrates the rotor core in the axial direction. As a result, stress may concentrate in the bridge portion between two adjacent magnet insertion holes in the circumferential direction of the rotor core, reducing the mechanical strength.

The object of the present invention is to provide a rotating electric machine that can reduce stress concentration in the bridge section and prevent a decrease in the mechanical strength of the rotor core.

In order to achieve the above object, the present invention provides a rotor core, comprising: a shaft insertion hole penetrating the rotor core in an axial direction of the rotor core; a plurality of magnet insertion holes arranged along an outer periphery of the rotor core in a cross section of the rotor core perpendicular to the axial direction of the rotor core and provided in the rotor core along the axial direction of the rotor core; a plurality of first bridge sections provided on the rotor core so that each of the plurality of magnet insertion holes is located between two adjacent magnet insertion holes in the circumferential direction of the rotor core; The rotor core is provided with a plurality of first buffer holes whose width in the circumferential direction of the rotor core is wider than the plurality of first bridge portions, and a plurality of second buffer holes located between each of the plurality of magnet insertion holes and the shaft insertion hole, and whose cross-sectional shape of the rotor core is a ring-shaped, long hole along the circumferential direction of the rotor core, wherein one of the plurality of magnet insertion holes is arranged between two adjacent first bridge portions of the plurality of first bridge portions in the circumferential direction of the rotor core, and no other bridge portions are present, and the plurality of first buffer holes and the plurality of second buffer holes are arranged so that the first buffer holes and the second buffer holes appear alternately on the circumference of the same circle centered on the rotor core.

According to the present invention, it is possible to reduce stress concentration in the bridge portion and prevent a decrease in the mechanical strength of the rotor. Problems, configurations, and effects other than those described above will become clear from the description of the following embodiment.

1 is a half-sectional view of a permanent magnet rotating electric machine according to a first embodiment of the present invention; 1 is a cross-sectional view of a rotor core according to a first embodiment of the present invention, taken perpendicular to an axial direction of the rotor core. 3 is a cross-sectional view taken along line AOB in FIG. 2. 5 is a cross-sectional view of another rotor core according to the first embodiment of the present invention, taken perpendicular to the axial direction of the rotor core. FIG. 5 is a cross-sectional view taken along line AOB in FIG. 4. 5 is a cross-sectional view of another rotor core according to the first embodiment of the present invention, taken perpendicular to the axial direction of the rotor core. FIG. 5 is a cross-sectional view of another rotor core according to the first embodiment of the present invention, taken perpendicular to the axial direction of the rotor core. FIG. 5 is a cross-sectional view of a rotor core according to a second embodiment of the present invention, taken perpendicular to the axial direction of the rotor core. FIG. 11 is a cross-sectional view of a rotor core according to a third embodiment of the present invention, taken perpendicular to the axial direction of the rotor core. FIG. 10 is a cross-sectional view of a rotor core according to a fourth embodiment of the present invention, taken perpendicular to the axial direction of the rotor core. FIG. 13 is a cross-sectional view of a rotor core according to a fifth embodiment of the present invention, taken perpendicular to the axial direction of the rotor core. FIG. 13 is a cross-sectional view of a rotor core according to a sixth embodiment of the present invention, taken perpendicular to the axial direction of the rotor core. FIG. 13 is a cross-sectional view of a rotor core according to a seventh embodiment of the present invention, taken perpendicular to the axial direction of the rotor core. FIG.

The configuration and operation of the permanent magnet rotating electric machine according to the first to seventh embodiments of the present invention will be described below with reference to the drawings. Note that the same reference numerals in each drawing indicate the same parts.

First Embodiment
1 is a half-sectional view of a permanent magnet rotating electric machine according to a first embodiment of the present invention. The permanent magnet rotating electric machine 10 according to the first embodiment of the present invention is a permanent magnet rotating electric machine having an interior permanent magnet (IPM) structure.

As shown in FIG. 1, the permanent magnet rotating electric machine 10 includes a stator 1, a rotor 2, a shaft 3, a bearing 4, a load side end bracket 5a, a non-load side end bracket 5b, a fan 6, an end cover 7, and a housing 8.

The stator 1 is an armature and includes a stator core 11. The stator core 11 is a cylindrical core made of laminated electromagnetic steel sheets, with multiple teeth (not shown) on its inner circumference, and coils 12 wound around the multiple teeth. The outer circumference of the stator core 11 is covered by a cylindrical housing 8, and the stator 1 is fixed to the housing 8.

The rotor 2 is a field magnet that is inserted into the internal space of the stator 1 and is rotatably attached to the stator 1 with a specified gap between them. The rotor 2 has a rotor core 21. The rotor core 21 is a cylindrical core made of laminated steel plates. The rotor core 21 has multiple magnet insertion holes 21a formed in the circumferential direction of the rotor core 21 along the axial direction of the rotor core 21. A permanent magnet 22 is inserted into each of the multiple magnet insertion holes 21a.

Retaining members 23 that hold the permanent magnets 22 inside the rotor core 21 are attached to both ends of the rotor core 21 and are fixed by fastening members 24 inserted into the fastening holes 21b. Therefore, the permanent magnets 22 are sandwiched between the retaining members 23 and held inside the rotor core 21. The permanent magnets 22 may be fixed to the magnet insertion holes 21a with an adhesive or the like.

The shaft 3 is inserted into the shaft hole 21c, which is a through hole provided in the central axis of the rotor core 21, and the rotor core 21 is connected to the shaft 3 by an interference fit such as press fitting or shrink fitting. The shaft 3 is rotatably supported by two bearings 4 and rotates together with the rotor core 21.

The shaft 3 serves as the output shaft when the permanent magnet rotating electric machine 10 is used as an electric motor, and serves as the input shaft when the permanent magnet rotating electric machine 10 is used as a generator.

The two bearings 4 are fixed to the load side end bracket 5a and the anti-load side end bracket 5b. In this embodiment, ball bearings are used as the bearings 4, but roller bearings may also be used. The load side end bracket 5a and the anti-load side end bracket 5b are disk-shaped parts that are attached to the ends of the housing 8 and close the opening of the housing 8.

The fan 6 is a component for cooling the permanent magnet rotating electric machine 10, and is attached to the end of the shaft 3 on the non-load side and covered by the end cover 7.

The permanent magnet rotating electric machine 10 configured in this manner becomes an electric motor that outputs torque from the shaft 3 by supplying power to the stator 1, and becomes a generator that outputs power from the stator 1 by inputting rotational power to the shaft 3.

Figure 2 is a cross-sectional view of the rotor core 21 according to the first embodiment of the present invention, perpendicular to the axial direction of the rotor core 21, and Figure 3 is a cross-sectional view taken along line A-O-B in Figure 2. The rotor core 21 has multiple (six in this embodiment) magnet insertion holes 21a, multiple (six in this embodiment) fastening holes 21b, one shaft hole 21c, and multiple (six in this embodiment) first buffer holes 21d.

The multiple magnet insertion holes 21a are arranged along the outer periphery of the rotor core 21 in a cross section of the rotor core 21 that is perpendicular to the axial direction of the rotor core 21 (hereinafter referred to as the "transverse section of the rotor core 21"), and are provided in the rotor core 21 along the axial direction of the rotor core 21. Furthermore, the shape of each of the multiple magnet insertion holes 21a in the transverse section of the rotor core 21 is a rectangle with a short diameter in the radial direction of the rotor core 21.

It is preferable that each of the multiple magnet insertion holes 21a is a through hole. This is because the rotor core 21 is usually manufactured by stacking punched steel plates. Therefore, it is difficult to process each of the multiple magnet insertion holes 21a after the steel plates are stacked, so they are punched into the steel plates before they are stacked. Therefore, if each of the multiple magnet insertion holes 21a is a through hole, it is possible to stack steel plates in which each of the multiple magnet insertion holes 21a has been punched, thereby reducing manufacturing costs.

In the cross section of the rotor core 21, the magnet insertion holes 21a have a circumferential width W2 that is greater than the radial width W1. In addition, each of the magnet insertion holes 21a is located on each side of a polygon H (a regular hexagon in this embodiment).

A first bridge portion 21e is provided between two adjacent magnet insertion holes 21a in the circumferential direction of the rotor core 21. That is, the rotor core 21 is provided with a plurality of first bridge portions 21e. The inner diameter portion 211 and the outer diameter portion 212 of the rotor core 21, which are separated by the plurality of magnet insertion holes 21a arranged in the circumferential direction of the rotor core 21, are connected by the first bridge portion 21e. Furthermore, the width W3 of the first bridge portion 21e in the circumferential direction of the rotor core 21 is correlated with the width W2 of the magnet insertion holes 21a in the circumferential direction of the rotor core 21.

The fastening hole 21b is a through hole provided between the first bridge portion 21e and the first buffer hole 21d. A fastening member 24 that fixes the holding member 23 is inserted into the fastening hole 21b. Note that instead of the holding member 23 and the fastening member 24, the permanent magnet 22 can also be fixed to the magnet insertion hole 21a with an adhesive or the like. In this case, it is not necessary to provide the fastening hole 21b in the rotor core 21 (see Figures 4 and 5).

As described above, the shaft hole 21c is a through hole provided in the central axis of the rotor core 21. The inner diameter of the shaft hole 21c is smaller than the outer diameter of the shaft 3 in order to connect the rotor core 21 to the shaft 3 by an interference fit. Therefore, a pressure corresponding to the dimensional difference (tightening) between the outer diameter of the shaft 3 and the inner diameter of the shaft hole 21c is applied to the inner circumferential surface of the shaft hole 21c from the outer circumferential surface of the shaft 3. Therefore, inside the rotor core 21, a stress due to the pressure corresponding to the tightening is generated in the radial direction of the rotor core 21 (hereinafter referred to as the tightening stress).

The first buffer hole 21d is located between one of the first bridge portions 21e and the shaft hole 21c, and is provided in the rotor core 21 along the axial direction of the rotor core 21.

The cross-sectional shape of each of the first buffer holes 21d is an annular sector along the circumferential direction of the rotor core 21.

Furthermore, it is preferable that the first buffer hole 21d is a through hole. This is because, like the magnet insertion hole 21a, it not only reduces manufacturing costs, but also has an effect on cooling the rotor 2.

The width W4 of the first buffer hole 21d in the circumferential direction of the rotor core 21 is wider than the width W3 of the first bridge portion 21e in the circumferential direction of the rotor core 21. In addition, the width W4 of the first buffer hole 21d in the circumferential direction of the rotor core is wider than the width W5 in the radial direction of the rotor core 21.

The inner surfaces 21g and 21h of the first buffer hole 21d at the end in the circumferential direction of the rotor core 21 are flat. In addition, the inner surfaces 21i and 21j of the first buffer hole 21d that face the radial direction of the rotor core 21 are curved surfaces that run along the circumferential direction of the rotor core 21.

The first buffer holes 21d are arranged in a plurality of rows in the circumferential direction of the rotor core 21. That is, the rotor core 21 is provided with a plurality of first buffer holes 21d. In addition, a second bridge portion 21f is provided between each pair of adjacent first buffer holes 21d.

The second bridge portion 21f is a portion that connects the inner portion and the outer portion of the multiple first buffer holes 21d of the rotor core 21. The magnet insertion hole 21a is located on the outer diameter side of the rotor core 21 of the second bridge portion 21f. In addition, the width W6 of the second bridge portion 21f in the circumferential direction of the rotor core 21 is correlated with the width W4 of the first buffer holes 21d in the radial direction of the rotor core 21.

The reason for providing the first buffer hole 21d in the rotor core 21 in the present invention is as follows. The characteristics of a permanent magnet rotating electric machine change depending on the size and arrangement of the permanent magnets. Therefore, the shape and arrangement of the magnet insertion holes provided in the rotor core are important factors in designing a permanent magnet rotating electric machine. At the same time, it is also necessary to consider the effect of the shape and arrangement of the magnet insertion holes on the strength of the rotor core.

Factors that affect the strength of the rotor core include external forces acting on the rotor core and stresses that remain in the steel plates when each of the laminated steel plates that form the rotor core is punched. External forces acting on the rotor core include pressure from the outer periphery of the shaft 3 and centrifugal forces that occur in the rotor core when the rotor rotates. These external forces generate stress inside the rotor core.

A number of magnet insertion holes are provided inside the rotor core in the circumferential direction of the rotor core. In a rotor core configured in this manner, stress increases locally in the first bridge portion located between two adjacent magnet insertion holes in the circumferential direction of the rotor core, resulting in stress concentration.

In the first bridge section where stress concentration occurs, fatigue strength may decrease, potentially shortening the rotor's lifespan. Therefore, the challenge is to mitigate stress concentration in the first bridge section 21e and prevent a decrease in fatigue strength.

To solve this problem, the permanent magnet rotating electric machine 10 and rotor core 21 according to this embodiment are provided with a first buffer hole 21d that is located between the shaft hole 21c and the first bridge portion 21e and has a width W4 in the circumferential direction of the rotor core 21 that is wider than the width W3 of the first bridge portion 21e.

By providing the first buffer hole 21d, the phenomenon of changing the stress distribution (interference effect) acts on the first bridge portion 21e, which is a stress concentration portion, and the maximum stress of the first bridge portion 21e becomes smaller. Therefore, the stress concentration occurring in the first bridge portion 21e can be mitigated, and the deterioration of the mechanical strength of the rotor 2 can be suppressed.

To confirm the above effect, a numerical analysis of the stress distribution of the rotor core was performed under specified conditions. As a result, the maximum stress of the first bridge portion 21e in the model of the rotor core 21 provided with the first buffer hole 21d was approximately 10% smaller than the maximum stress of the first bridge portion in the model of the rotor core not provided with the first buffer hole. Therefore, the effect of providing the first buffer hole 21d in the rotor core 21 according to this embodiment was confirmed.

In particular, the rotor core 21 can suppress leakage magnetic flux and demagnetization of the permanent magnets by providing gaps at both ends of the magnet insertion hole 21a in the circumferential direction of the rotor core. However, the width W3 of the first bridge portion becomes even narrower. This further increases stress concentration in the first bridge portion. This further reduces the fatigue strength of the first bridge portion, which may further shorten the life of the rotor.

However, by providing the first buffer hole 21d, an interference effect is exerted on the first bridge portion 21e, which is a stress concentration portion, and the maximum stress of the first bridge portion 21e is reduced. Therefore, the stress concentration occurring in the first bridge portion 21e can be alleviated, and the deterioration of the mechanical strength of the rotor 2 can be suppressed. Therefore, by providing gaps at both ends of the magnet insertion hole 21a in the circumferential direction of the rotor core, the stress concentration in the first bridge portion 21e can be alleviated, and the deterioration of the mechanical strength of the rotor 2 can be suppressed.

The first buffer hole 21d has a width W4 in the circumferential direction of the rotor core that is wider than the width W5 in the radial direction of the rotor core 21. This configuration ensures a magnetic path on the inner diameter side of the multiple magnet insertion holes 21a of the rotor core 21.

In addition, the inner surfaces 21g, 21h of the first buffer hole 21d at both ends in the circumferential direction of the rotor core 21 are configured as flat surfaces. With this configuration, the interference effect acts more widely on the first bridge portion 21e, which is a stress concentration portion, than in the first embodiment, and the maximum stress of the first bridge portion 21e is further reduced. Therefore, the stress concentration occurring in the first bridge portion 21e can be further alleviated, and the deterioration of the mechanical strength of the rotor 2 can be further suppressed.

To confirm this effect, a numerical analysis of the stress distribution of the rotor core was performed under specified conditions. As a result, the maximum stress of the first bridge portion 21e in a model of the rotor core 21 in which the inner surfaces 21g, 21h are flat was smaller than the maximum stress of the first bridge portion in a model of the rotor core in which the inner surfaces 21g, 21h are curved. Therefore, the effect of forming the inner surfaces 21g, 21h of the first buffer hole 21d of the rotor core 21 at both ends in the circumferential direction of the rotor core 21 of the present embodiment as flat surfaces was confirmed.

The cross-sectional shape of each of the first buffer holes 21d may be rectangular (square) as shown in FIG. 6.

The width W4 of the first buffer hole 21d in the circumferential direction of the rotor core 21 can be selected arbitrarily. For example, as shown in FIG. 7, the width W4 of the first buffer hole 21d in the rotor core 21 in the circumferential direction of the rotor core 21 can be made narrower than in the embodiment shown in FIG. 4, and the width W6 of the second bridge portion 21f in the circumferential direction of the rotor core 21 can be made wider than in the embodiment shown in FIG. 4, thereby enhancing the strength of the second bridge portion 21f.

By adopting such a configuration, the maximum stress of the first bridge portion 21e and the second bridge portion 21f can be reduced. Therefore, the rotor core 21 according to this embodiment can reduce the stress concentration that occurs in the first bridge portion 21e and the second bridge portion 21f, and suppress the deterioration of the mechanical strength of the rotor 2.

Second Embodiment
FIG. 8 is a cross-sectional view of a rotor core 221 perpendicular to the axial direction of the rotor core 221 according to the second embodiment of the present invention.

The rotor core 221 according to this embodiment differs from the rotor core 21 according to the first embodiment in the following respects. That is, the radial positions of the first buffer hole 221d and the second bridge portion 221f provided in the inner diameter portion 2211 of the rotor core 221 according to this embodiment are closer to the first bridge portion 21e than the shaft hole 21c, compared to the radial positions of the first buffer hole 21d and the second bridge portion 21f provided in the inner diameter portion 211 of the rotor core 21 according to the first embodiment.

By adopting such a configuration, the interference effect is further exerted on the first bridge portion 21e, which is a stress concentration portion, and the maximum stress of the first bridge portion 21e is smaller than in the first embodiment. Therefore, the stress concentration occurring in the first bridge portion 21e can be mitigated more than in the first embodiment, and the decrease in the mechanical strength of the rotor 2 can be suppressed more than in the first embodiment.

To confirm the above effects, a numerical analysis of the stress distribution of the rotor core was performed under specified conditions. As a result, the maximum stress of the first bridge portion 21e in the model of the rotor core 221 according to this embodiment was approximately 5% smaller than the maximum stress of the first bridge portion in the model of the rotor core 21 according to the first embodiment. Therefore, the effects of the features of the rotor core 221 according to this embodiment were confirmed.

On the other hand, if the radial positions of the first buffer hole 221d and the second bridge portion 221f of the inner diameter portion 2211 of the rotor core 221 are closer to the first bridge portion 21e than to the shaft hole 21c, compared to the radial positions of the first buffer hole 21d and the second bridge portion 21f provided in the inner diameter portion 211 of the rotor core 21 in the first embodiment, the first buffer hole 221d and the second bridge portion 221f will be closer to the magnet insertion hole 21a.

In this case, a first buffer hole 221d, which is an air gap, is formed near the permanent magnet 22, increasing the magnetic resistance of the rotor core 21 and making it difficult for magnetic flux to flow.

Therefore, it is preferable to select the radial positions of the first buffer hole 221d and the second bridge portion 221f of the inner diameter portion 2211 of the rotor core 221 as appropriate, taking into account the characteristics of the permanent magnet rotating electric machine and the strength of the rotor core.

Third Embodiment
FIG. 9 is a cross-sectional view of a rotor core 321 perpendicular to the axial direction of the rotor core 321 according to the third embodiment of the present invention.

The rotor core 321 according to this embodiment differs from the rotor core 21 according to the first embodiment in the following respects. That is, the magnet insertion hole 321a provided in the rotor core 321 according to this embodiment is provided with a partition portion 321k. The partition portion 321k is a portion that connects the inner diameter portion 3211 and the outer diameter portion 3212 of the rotor core 321 in order to divide the magnet insertion hole 321a in the longitudinal direction of the magnet insertion hole 321a.

This configuration makes it possible to reinforce the rotor core 321 around the magnet insertion hole 321a. Therefore, the stress concentration that occurs in the first bridge portion 21e can be mitigated more than in the first embodiment. Therefore, this embodiment can suppress the decrease in the mechanical strength of the rotor 2 more than the first embodiment.

To confirm the above effects, a numerical analysis of the stress distribution of the rotor core was performed under specified conditions. As a result, the maximum stress in the first bridge portion 21e of the model of the rotor core 321 according to this embodiment was approximately 30% smaller than the maximum stress in the first bridge portion of the model of the rotor core 21 according to the first embodiment. Therefore, the effects of the features of the rotor core 321 according to this embodiment were confirmed.

In the rotor core 321 according to this embodiment, one partition portion 321k is provided in the magnet insertion hole 321a. However, this is merely an example. Multiple partition portions 321k may be provided in the magnet insertion hole 321a, and the inner diameter portion 3211 and the outer diameter portion 3212 of the rotor core 321, which are separated by the multiple magnet insertion holes 321a, may be connected by the multiple partition portions 321k.

Fourth Embodiment
10 is a cross-sectional view of a rotor core 421 according to a fourth embodiment of the present invention, taken perpendicular to the axial direction of the rotor core 421. The rotor core 421 according to this embodiment differs from the rotor core 21 according to the first embodiment in the following respects.

That is, in the rotor core 21 according to the first embodiment, only one first buffer hole 21d is provided in the radial direction of the rotor core 21 between the shaft hole 21c and the first bridge portion 21e. In contrast, in the rotor core 421 according to this embodiment, a plurality of first buffer holes (two first buffer holes 21d and 221d in FIG. 10) are provided in the radial direction of the rotor core 21 between the shaft hole 21c and the first bridge portion 21e. Therefore, in the rotor core 421 according to this embodiment, a plurality of second bridge portions (two second bridge portions 21f and 221f in FIG. 10) are provided in the radial direction of the rotor core 21, each of which is provided between two first buffer holes adjacent to each other in the circumferential direction of the rotor core 21 of the plurality of first buffer holes.

By adopting such a configuration, the interference effect acts more widely on the first bridge portion 21e, which is the stress concentration portion, than in the first embodiment, and the stress concentration coefficient can be further reduced compared to the first embodiment. Therefore, the maximum stress of the first bridge portion 21e is smaller than in the first embodiment. Therefore, the stress concentration occurring in the first bridge portion 21e can be mitigated more than in the first embodiment, and the decrease in the mechanical strength of the rotor 2 can be suppressed more than in the first embodiment.

To confirm the above effects, a numerical analysis of the stress distribution of the rotor core was performed under specified conditions. As a result, the maximum stress in the first bridge section 21e of the model of the rotor core 421 according to this embodiment was approximately 3% smaller than the maximum stress in the first bridge section of the model of the rotor core 21 according to the first embodiment. Therefore, the effects of the features of the rotor core 421 according to this embodiment were confirmed.

Fifth Embodiment
11 is a cross-sectional view of a rotor core 521 according to a fifth embodiment of the present invention, taken perpendicular to the axial direction of the rotor core 521. The rotor core 521 according to this embodiment differs from the rotor core 21 according to the first embodiment in the following respects.

That is, the rotor core 521 according to this embodiment is provided with a second buffer hole 521l. Similar to the first buffer hole 21d according to the first embodiment, the second buffer hole 521l is a long hole that penetrates the rotor core 21 in the axial direction of the rotor core 21 and has a circular sector shape in cross section. On the other hand, unlike the first buffer hole 21d according to the first embodiment, the second buffer hole 521l is provided between one of the multiple magnet insertion holes 21a and the shaft hole 21c.

In addition, in the rotor core 521 according to this embodiment, the width W54 of the first buffer hole 521d in the radial direction of the rotor core 521 is narrower than the width W4 of the first buffer hole 21d in the radial direction of the rotor core 21 according to the first embodiment.

The second buffer hole 521l is provided between each pair of adjacent first buffer holes 521d of the multiple (six in this embodiment) first buffer holes 521d in this embodiment. That is, the rotor core 521 is provided with multiple (six in this embodiment) second buffer holes 521l. Furthermore, the multiple first buffer holes 521d and the multiple second buffer holes 521l are alternately arranged on the same circumference of the rotor core 521.

In addition, in the rotor core 21 according to the first embodiment, a second bridge portion 21f is provided between two adjacent first buffer holes 21d of the multiple first buffer holes 21d. In contrast, in the rotor core 521 according to this embodiment, two bridge portions 521f are provided between each of the multiple first buffer holes 521d and the multiple second buffer holes 521l that are adjacent in the circumferential direction of the rotor core 521. As a result, the number of second bridge portions 521f in this embodiment is twice (12) the number of second bridge portions 21f in the first embodiment (6).

By adopting such a configuration, an interference effect occurs in the first bridge portion 21e, which is a stress concentration portion, and the stress concentration coefficient is reduced. As a result, the maximum stress in the first bridge portion 21e is reduced. Therefore, the stress concentration occurring in the first bridge portion 21e can be mitigated, and a decrease in the mechanical strength of the rotor 2 can be suppressed.

To confirm the above effect, a numerical analysis of the stress distribution of the rotor core was performed under specified conditions. As a result, the maximum stress of the first bridge portion 21e in the model of the rotor core 521 provided with the first buffer holes 521d and the second buffer holes 521l was approximately 2% smaller than the maximum stress of the first bridge portion in the model of the rotor core not provided with the first buffer holes 521d and the second buffer holes 521l. Therefore, the effect of providing the first buffer holes 521d and the second buffer holes 521l in the rotor core 521 according to this embodiment was confirmed.

In addition, by adopting the above-mentioned configuration, the interference effect acts more widely on the stress concentration portion on the inner circumferential surface of the shaft hole 21c than in the first embodiment, and the maximum stress on the stress concentration portion of the shaft hole 21c is smaller than in the first embodiment. Therefore, the stress concentration occurring on the inner circumferential surface of the shaft hole 21c can be mitigated more than in the first embodiment, and the decrease in the mechanical strength of the rotor 2 can be suppressed more than in the first embodiment.

To confirm the above effects, a numerical analysis of the stress distribution of the rotor core was performed under specified conditions. As a result, the maximum stress on the inner circumferential surface of the shaft hole 21c in the model of the rotor core 521 of this embodiment was approximately 15% smaller than the maximum stress on the inner circumferential surface of the shaft hole 21c in the model of the rotor core 21 of the first embodiment. Therefore, the effect of providing the first buffer hole 521d and the second bridge portion 521f in the rotor core 521 of this embodiment was confirmed.

Sixth Embodiment
FIG. 12 is a cross-sectional view of a rotor core 621 perpendicular to the axial direction of the rotor core 621 according to the sixth embodiment of the present invention.

The rotor core 621 according to this embodiment differs from the rotor core 21 according to the first embodiment in the following respects. That is, in the rotor core 621 according to the sixth embodiment, a second buffer hole 621l is provided between one of the multiple magnet insertion holes 21a and the shaft hole 21c. The second buffer hole 621l is provided between a second bridge portion 21f provided between two adjacent first buffer holes 21d among the multiple first buffer holes 21d arranged in the circumferential direction of the rotor core 621, and a magnet insertion hole 21a located on the outer diameter side of the rotor core 621 of the second bridge portion 21f. A third bridge portion 621m is provided between each of the two adjacent second buffer holes 621l among the multiple second buffer holes 621l.

By adopting such a configuration, the interference effect acts more widely on the first bridge portion 21e, which is a stress concentration portion, than in the first embodiment, and the maximum stress on the first bridge portion 21e is smaller than in the first embodiment. Therefore, the stress concentration occurring on the first bridge portion 21e can be mitigated more than in the first embodiment, and the decrease in the mechanical strength of the rotor 2 can be suppressed more than in the first embodiment.

To confirm the above effects, a numerical analysis of the stress distribution of the rotor core was performed under specified conditions. As a result, the maximum stress in the first bridge portion 21e of the model of the rotor core 621 according to this embodiment was approximately 10% smaller than the maximum stress in the first bridge portion 21e of the model of the rotor core 21 according to the first embodiment. Therefore, the effects of the features of the rotor core 621 according to this embodiment were confirmed.

In addition, in the rotor core 621 according to this embodiment, a second buffer hole 621l is provided on the outer diameter side of the rotor core 621 of the second bridge portion 21f. With this configuration, the interference effect acts more widely on the stress concentration portion on the inner circumferential surface of the shaft hole 21c than in the first embodiment, and the maximum stress on the stress concentration portion of the shaft hole 21c is smaller than in the first embodiment. Therefore, the stress concentration occurring on the inner circumferential surface of the shaft hole 21c can be mitigated more than in the first embodiment, and the decrease in the mechanical strength of the rotor 2 can be suppressed more than in the first embodiment.

To confirm the above effects, a numerical analysis of the stress distribution of the rotor core was performed under specified conditions. As a result, the maximum stress on the inner peripheral surface of the shaft hole 21c in the model of the rotor core 621 according to the sixth embodiment was approximately 6% smaller than the maximum stress on the inner peripheral surface of the shaft hole 21c in the model of the rotor core 21 according to the first embodiment. Therefore, the effect of providing the second buffer hole 621l and the third bridge portion 621m in the rotor core 621 according to this embodiment was confirmed.

Seventh Embodiment
FIG. 13 is a cross-sectional view of a rotor core 721 perpendicular to the axial direction of the rotor core 721 according to the seventh embodiment of the present invention.

The rotor core 721 according to this embodiment differs from the rotor core 21 according to the first embodiment in the following respects. That is, the rotor core 721 according to this embodiment has a magnet insertion hole 321a with a partition portion 321k, as in the third embodiment. Therefore, the rotor core 721 according to this embodiment has the same effect as the rotor core 321 of the third embodiment.

In addition, in the rotor core 721 according to this embodiment, the multiple first buffer holes 521d and the multiple second buffer holes 521l are arranged alternately on the same circumference of the rotor core 521, as in the fifth embodiment. Therefore, the rotor core 721 according to this embodiment also achieves the same effects as the rotor core 521 of the fifth embodiment.

To confirm the above effects, a numerical analysis of the stress distribution of the rotor core was performed under specified conditions. As a result, the maximum stress in the first bridge portion 21e of the model of the rotor core 721 according to this embodiment was approximately 20% smaller than the maximum stress in the first bridge portion of the model of the rotor core 21 according to the first embodiment. In addition, the maximum stress on the inner surface of the shaft hole 21c in the model of the rotor core 721 according to this embodiment was approximately 20% smaller than the maximum stress on the inner surface of the shaft hole 21c in the model of the rotor core 21 according to the first embodiment. Therefore, the effects due to the characteristics of the rotor core 721 according to this embodiment were confirmed.

The present invention is not limited to the above-described embodiments, but includes various modified examples. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and are not necessarily limited to those having all of the configurations described. It is also possible to replace part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. It is also possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

The embodiment of the present invention shows an embodiment in which the number of poles is six, and each of the multiple magnet insertion holes 21a is arranged based on each side of a regular hexagon in the cross section of the rotor core 21. However, the present invention is not limited to this, and the rotor core 21 may have multiple poles (number of poles n), and each of the multiple magnet insertion holes 21a may be arranged based on each side of a regular n-gon in the cross section of the rotor core 21.

1... stator, 2... rotor, 21, 221, 321, 421, 521, 621, 721... rotor core, 21a, 321a... magnet insertion hole, 21c... shaft hole, 21d, 221d, 521d... first buffer hole, 21e... first bridge section, 21f, 521f... second bridge section, 521l, 621l... second buffer hole, 321k... partition section, 10... permanent magnet rotating electric machine, W3... width of first bridge section in circumferential direction of rotor core, W4... width of first buffer hole in circumferential direction of rotor core, W5... width of first buffer hole in radial direction of rotor core, W6... width of second bridge section in circumferential direction of rotor core

Claims (12)

A rotor core;
a shaft insertion hole that penetrates the rotor core in an axial direction of the rotor core;
a plurality of magnet insertion holes arranged along an outer periphery of the rotor core in a cross section of the rotor core perpendicular to the axial direction of the rotor core and provided in the rotor core along the axial direction of the rotor core;
a plurality of first bridge portions provided on the rotor core such that each bridge portion is located between two adjacent magnet insertion holes in a circumferential direction of the rotor core;
a plurality of first buffer holes that are located between each of the plurality of first bridge portions and the shaft insertion hole, that are provided in the rotor core along the axial direction of the rotor core, and that have a width in the circumferential direction of the rotor core that is wider than that of the plurality of first bridge portions;
a plurality of second buffer holes each located between the plurality of magnet insertion holes and the shaft insertion hole, the second buffer holes having a cross-sectional shape of an annular sector extending along a circumferential direction of the rotor core ,
one of the plurality of magnet insertion holes is disposed between two of the first bridge portions adjacent to each other in the circumferential direction of the rotor core, and no other bridge portions are present;
A rotating electric machine characterized in that the multiple first buffer holes and the multiple second buffer holes are arranged so that the first buffer holes and the second buffer holes appear alternately on the circumference of the same circle centered on the rotor core. 2. The rotating electric machine according to claim 1,
A rotating electric machine, wherein the first buffer hole has a width in a circumferential direction of the rotor core that is larger than a width in a radial direction of the rotor core. 2. The rotating electric machine according to claim 1,
a first buffer hole having a circumferential end portion in a circumferential direction of the rotor core, the first buffer hole having a flat inner surface, and a second buffer hole having a circumferential end portion in a circumferential direction of the rotor core. 2. The rotating electric machine according to claim 1,
a first buffer hole disposed radially of the rotor core and arranged to be closer to the first bridge portion than the shaft insertion hole is to be arranged radially of the rotor core; 2. The rotating electric machine according to claim 1,
A rotating electric machine, characterized in that the shape of the first buffer hole in a cross section of the rotor core is rectangular. 2. The rotating electric machine according to claim 1,
A rotating electric machine comprising: a rotor core having a plurality of first buffer holes provided in a radial direction of the rotor core. A rotor core;
a shaft insertion hole that penetrates the rotor core in an axial direction of the rotor core;
a plurality of magnet insertion holes arranged along an outer periphery of the rotor core in a cross section of the rotor core perpendicular to the axial direction of the rotor core and provided in the rotor core along the axial direction of the rotor core;
a plurality of first bridge portions provided on the rotor core such that each bridge portion is located between two adjacent magnet insertion holes in a circumferential direction of the rotor core;
a plurality of first buffer holes each positioned between the plurality of first bridge portions and the shaft insertion hole, the width of each first buffer hole being wider than the width of each first bridge portion in the circumferential direction of the rotor core;
a plurality of second buffer holes each located between the plurality of magnet insertion holes and the shaft insertion hole, the second buffer holes having a cross-sectional shape of an annular sector extending along a circumferential direction of the rotor core ,
A rotor characterized in that, among the multiple first bridge portions, one of the multiple magnet insertion holes is arranged between two adjacent first bridge portions in the circumferential direction of the rotor core, and no other bridge portions are present, and the multiple first buffer holes and the multiple second buffer holes are arranged so that the first buffer holes and the second buffer holes appear alternately on the circumference of the same circle centered on the rotor core. 8. The rotor according to claim 7,
A rotor, wherein the first buffer hole has a width in a circumferential direction of the rotor core that is larger than a width in a radial direction of the rotor core. 8. The rotor according to claim 7,
A rotor, wherein an inner surface of the first buffer hole at an end portion in a circumferential direction of the rotor core is formed of a flat surface. 8. The rotor according to claim 7,
A rotor, characterized in that the first buffer hole is located closer to the first bridge portion in the radial direction of the rotor core than the shaft insertion hole. 8. The rotor according to claim 7,
A rotor, wherein the first buffer hole has a rectangular shape in a cross section of the rotor core. 8. The rotor according to claim 7,
A rotor, characterized in that a plurality of the first buffer holes are provided in a radial direction of the rotor core.

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