WO2011002043A1 - Permanent magnet type rotary electrical machine - Google Patents

Abstract

Disclosed is a permanent magnet type rotary electrical machine in which generation of leakage magnetic flux can be effectively suppressed, while centrifugal force intensity can be preserved. The electrical machine is equipped with a rotor (5) in which are embedded three permanent magnets (8a to 8c) for a single pole in the interior of a rotor core (6). The rotor (5) is rotatably arranged, with the provision of a rotation gap, on a stator comprising a stator coil accommodated in the interior of a slot. Magnet insertion holes, in which the permanent magnets (8a to 8c) are embedded, are provided in the rotor core (6) adjacent to one another in a substantially U-shaped formation directed towards the outer peripheral surface of the rotor (5). Cavities (9a1, 9a2, 9b1, 9b2, 9c1 and 9c2) are formed at the side faces of the permanent magnets (8a to 8c) which are embedded in the magnet insertion holes.

Description

Permanent magnet type rotating electric machine

The present invention relates to a rotating electrical machine such as a vehicular electric motor, and more particularly to a rotor structure of a rotating electrical machine in which a permanent magnet is disposed inside the rotor.

There is an electric motor (permanent magnet type electric motor) with a built-in permanent magnet as one of rotating electric machines in which a permanent magnet is arranged inside the rotor. Compared with induction motors that are widely used in various fields, this permanent magnet type motor has a magnetic flux established by permanent magnets built into the rotor, so that no excitation current is required. As described above, since no current flows through the rotor conductor, secondary copper loss does not occur. Conventionally, induction motors have been used for electric vehicles equipped with motors for vehicles. However, in recent years, permanent magnet synchronous motors have been applied to improve efficiency, reduce size and increase output, and simplify the cooling structure. It is being considered.

In addition, the permanent magnet type motor includes a motor with a surface magnet structure (SPMM: Surface Permanent Magnet Motor) in which a permanent magnet is attached to the surface of the rotor, and a motor with an embedded magnet structure in which the permanent magnet is embedded in the rotor. (IPMM: Interior Permanent Magnet Motor), for example, the permanent magnet type reluctance rotating electrical machine shown in Patent Document 1 below belongs to the latter.

This permanent magnet type reluctance rotating electric machine has a rotor in which two permanent magnets are embedded in a circumferential direction at predetermined intervals in order to form a magnetic salient pole portion in a rotor core, One end of each permanent magnet is located closer to the outer periphery so as to form a thin tip portion between the outer periphery of the rotor core and the other end is closer to the center side. The chip portions are arranged so that the opening angle of the inner end angle of each chip portion is a predetermined electrical angle.

JP 2007-97290 A

By the way, most permanent magnet type motors used for electric vehicles have an embedded magnet structure in which a permanent magnet is embedded in a rotor.

Specifically, in a permanent magnet type electric motor used for an electric vehicle, a permanent magnet having a weight of 1 to several kg is embedded in a rotor having a large outer size (ie, radius). Rotates at a rotational speed of about 6000 rpm. For this reason, in the case of the surface magnet structure, a mechanism for firmly holding the permanent magnet must be provided separately, and the configuration is difficult. For this reason, a permanent magnet type electric motor for an electric vehicle is often used with an embedded magnet structure. However, even with a permanent magnet type electric motor having an embedded magnet structure, it is a matter of course that the rotor is required to have a structure that only receives the centrifugal force generated in the permanent magnet.

On the other hand, in the rotating electrical machine disclosed in Patent Document 1, since the permanent magnet is held only by the strength of the rotor core in the rotor surface direction, the outer size of the rotor is increased. In such a case, there is a concern that the strength against centrifugal force is insufficient. Therefore, when the permanent magnet type electric motor shown in Patent Document 1 is applied to, for example, an electric vehicle, there is a need to insert the permanent magnet into the inner side (center side) of the rotor. As a result, this time, There is a concern that the leakage magnetic flux at both ends of the permanent magnet increases, leading to a decrease in driving torque.

The present invention has been made in view of the above, and an object of the present invention is to provide a permanent magnet type rotating electrical machine that effectively suppresses generation of leakage magnetic flux while maintaining strength against centrifugal force.

In order to solve the above-described problems and achieve the object, a permanent magnet type rotating electric machine according to the present invention includes a stator having a stator coil housed in a slot, and the stator rotating through a rotation gap. A rotor core that can be arranged, and a rotor in which three or more permanent magnets are embedded per pole in the rotor core, and the permanent magnet is embedded in the rotor core The magnet insertion holes are arranged in a substantially U shape toward the outer peripheral surface of the rotor, and a cavity is formed in a side surface portion of the permanent magnet embedded in each of the magnet insertion holes.

According to the permanent magnet type rotating electrical machine of the present invention, there is an effect that generation of leakage magnetic flux can be effectively suppressed while maintaining strength against centrifugal force.

FIG. 1 is a cross-sectional view of a permanent magnet type electric motor according to a first embodiment of the present invention. FIG. 2 is a schematic cross-sectional view showing the structure of the rotor shown in FIG. FIG. 3 is a partially enlarged view when a permanent magnet is not inserted. FIG. 4 is a partially enlarged view when a permanent magnet is inserted. FIG. 5 is a diagram for explaining the influence of the leakage flux of the permanent magnet. FIG. 6 is a diagram illustrating a conventional example as a comparison target. FIG. 7 is a diagram comparing the maximum stress generated in the magnet insertion hole between the prior art and the first embodiment. FIG. 8 is a schematic cross-sectional view showing the structure of the rotor core according to the second embodiment of the present invention. FIG. 9 is a schematic cross-sectional view showing the structure of the rotor core according to the third embodiment of the present invention. FIG. 10 is a partial enlarged view of the magnet insertion hole shown in FIG. 9 and a diagram for explaining the effect of the third embodiment. FIG. 11 is a schematic cross-sectional view showing the structure of the rotor core according to the fourth embodiment of the present invention. FIG. 12 is a diagram showing a modification of the configuration shown in FIG. FIG. 13: is a schematic cross section which shows the structure of the rotor core concerning Embodiment 5 of this invention. FIG. 14 is a diagram comparing the maximum stress generated in the magnet insertion hole between the first embodiment and the fifth embodiment. FIG. 15 is a diagram showing a modification of the configuration shown in FIG. FIG. 16 is a diagram showing another modification of the configuration shown in FIG. FIG. 17 is a schematic cross-sectional view showing the structure of the rotor core according to the sixth embodiment of the present invention. FIG. 18 is a schematic cross-sectional view showing the structure of the rotor core according to the seventh embodiment of the present invention. FIG. 19 is a schematic cross-sectional view showing the structure of the rotor core according to the eighth embodiment of the present invention. FIG. 20 is a cross-sectional view in the axial direction of a permanent magnet on both sides of the permanent magnet according to the ninth embodiment of the present invention. FIG. 21 is a sectional view in the axial direction of a permanent magnet on the center side among the permanent magnets according to the ninth embodiment of the present invention.

Hereinafter, a permanent magnet type rotating electrical machine according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. In addition, this invention is not limited by embodiment shown below.

Embodiment 1 FIG.
1 is a cross-sectional view of a permanent magnet type electric motor that is an example of a permanent magnet type rotating electrical machine according to a first embodiment of the present invention, and FIG. 2 shows the structure of a rotor in the permanent magnet type electric motor shown in FIG. It is a schematic cross section shown. 3 and 4 are enlarged views of a portion indicated by a broken line in the rotor of FIG. 2, FIG. 3 is a partially enlarged view when a permanent magnet is not inserted, and FIG. It is the elements on larger scale when the permanent magnet is inserted.

The permanent magnet type electric motor 1 according to the first exemplary embodiment includes a stator 2 and a rotor 5. The stator 2 includes a stator core 3 having a cylindrical shape, and a stator coil 4 disposed so as to be wound around the stator core 3. The stator core 3 is formed with slots 3a by intermittently forming teeth 3b on the inner peripheral side thereof, and the stator coil 4 has a conductor wire wound around the teeth 3b accommodated in each of the slots 3a. To be arranged.

The rotor 5 is produced by, for example, laminating and integrating a predetermined number of magnetic steel plates, the outer peripheral surface forms a cylindrical surface, and 18 magnet insertion holes 7 (see FIGS. 2 and 3) are arranged at an equiangular pitch. Rotor core 6 formed as described above and permanent magnets 8 (8a to 8c) housed in the respective magnet insertion holes 7, and can rotate with respect to the stator 2 through a rotation gap 18. It is arranged to become.

Here, as for the arrangement of the magnet insertion holes 7, as shown in FIG. 3, there are two magnet insertion holes 7a and 7c at both ends of one magnet insertion hole 7b. Further, six sets 7a to 7c of the magnet insertion holes 7 are arranged in a substantially U shape toward the outer peripheral surface of the rotor 5, as shown in FIG. Then, while the direction of the magnetic flux by the permanent magnets 8a to 8c, which is the first set of permanent magnets, is magnetized (magnetized) in such a direction as to converge toward the outer peripheral surface of the rotor 5, adjacent sets ( The permanent magnets 16 a to 16 c of the second set of permanent magnets are magnetized in a direction in which the direction of magnetic flux extends concentrically toward the center of the rotor 5. That is, in the rotor in the permanent magnet type electric motor according to the first embodiment, the permanent magnet group magnetized in such a direction that the direction of the magnetic flux by the permanent magnet converges toward the outer peripheral surface of the rotor, and the center of the rotor Permanent magnet groups magnetized in a direction concentrically extending toward the part are arranged alternately.

The reason why the direction of magnetization by the permanent magnet group is configured as described above is to make the induced voltage of the stator coil sinusoidal, and in applications that do not require the induced voltage of the stator coil to be sinusoidal. This is not the case. That is, the magnetization directions of the permanent magnet groups magnetized in the direction toward the outer peripheral surface of the rotor or in the direction toward the center of the rotor may be parallel.

Further, on both side surfaces of the permanent magnets 8a to 8c embedded in the magnet insertion holes 7a to 7c, there are hollow portions 9 as shown in FIG. 4 (cavities 9a1 and 9a2 on both side surfaces of the permanent magnet 8a and permanent magnets 8b). Cavities 9b1 and 9b2 are formed on both side surface portions, and cavity portions 9c1 and 9c2) are formed on both side surface portions of the permanent magnet 8c. The effect of the hollow portion 9 will be described later.

In FIG. 1, 36 slots 3a are arranged at equiangular pitches in the circumferential direction of the stator 2, and 6-pole motors (1) in which 18 permanent magnets 8 are embedded in the circumferential direction of the rotor 5. 6 slots per pole and 3 permanent magnets per pole) are shown as an example, but the number of poles of the motor, the number of slots, the number of permanent magnets, etc. are not limited to the configuration of FIG. Any number of selections are possible.

Next, the leakage flux of the permanent magnet 8 will be described with reference to FIG. 4 and FIG. FIG. 5 is a diagram for explaining the influence of the leakage magnetic flux of the permanent magnet 8.

The magnetic flux generated by the permanent magnets 8a to 8c returns to the rotor core 6 again (not shown) after passing through the core back portion 15 (see FIG. 1) of the stator core 3. However, as shown in FIG. 5, a part of the magnetic flux does not go to the core back portion 15 but stays in the rotor core 6 and returns to the permanent magnet 8 as a loop. There is a leakage flux 12 that becomes The leakage magnetic flux 12 does not contribute to torque and causes an increase in iron loss, so it is preferable to suppress it as much as possible.

Therefore, in the rotor according to the present embodiment, as shown in FIG. 4, with respect to the permanent magnet group arranged in a substantially U shape, the cavity portion on both sides of the magnet insertion hole 7 is more than the cavity other than both sides. I try to get bigger. In a specific configuration, the hollow portions 9b1 and 9b2 generated by embedding the permanent magnet 8b in the magnet insertion hole 7b are approximately equal in size, and the hollow portion generated by embedding the permanent magnet 8a in the magnet insertion hole 7a. In 9a1 and 9a2, the magnet insertion hole 7a is formed so that the hollow portion 9a1 is larger, and the hollow portions 9c1 and 9c2 generated by embedding the permanent magnet 8c in the magnet insertion hole 7c are the same as the hollow portion 9c2. The magnet insertion hole 7c is formed so as to be larger.

In other words, the cavity portion (for example, the cavity portion 9a1) formed on the outer peripheral side of the rotor core 6 is the cavity portion (for example, the cavity portions 9a2 and 9b1) formed on the center side of the rotor core 6. , ...), the shape of the magnet insertion hole 7 is formed to be a larger space. According to the rotor core 6 configured as described above, the leakage magnetic flux 12 due to the permanent magnet 8 is generated by the bridge portion 10a formed between the permanent magnets 8a and 8b and the bridge portion formed between the permanent magnets 8b and 8c. 10b and the bridge portions 11a and 11b respectively formed between the permanent magnets 8a and 8c and the outer peripheral surface of the rotor core 6 serve as magnetic flux paths. Therefore, it is possible to reduce the leakage flux by narrowing these magnetic flux paths.

Here, the bridge portions 10a, 10b and 11a, 11b are traded off with the centrifugal force intensity. However, in the rotor 5 in the present embodiment, the number of permanent magnets is divided into three to reduce the weight of each permanent magnet, and the three permanent magnets have a curvature as shown in the figure. The bridge portions 10a, 10b and 11a, 11b can be made thinner than the conventional configuration, and the leakage magnetic flux passing through these bridge portions can be reduced. Reduction is possible.

Next, the effect of the first embodiment will be described with reference to FIG. FIG. 7 is a diagram showing the maximum stress generated in the magnet insertion hole in comparison with the conventional example and the first embodiment. In FIG. 7, the conventional example is a value obtained by simulation of the maximum stress generated in the magnet insertion hole of the rotor disclosed in Patent Document 1. The arrangement configuration of the permanent magnets in Patent Document 1 is as shown in FIG. 6, and the permanent magnets 108 are arranged in a substantially V shape in the rotor core 106.

As shown in FIG. 7, if the maximum stress of the conventional example is “1”, the maximum stress of the first embodiment is 0.55, which is 45% lower than the conventional example. Therefore, according to the rotor of the first embodiment, it is possible to effectively suppress the generation of leakage magnetic flux while maintaining the strength against centrifugal force.

Further, according to the rotor of the first embodiment, it is possible to further reduce the thickness under a condition where the strength against the centrifugal force is constant, so that the leakage magnetic flux can be further reduced.

Embodiment 2. FIG.
FIG. 8 is a schematic cross-sectional view showing the structure of the rotor core according to the second embodiment of the present invention. In the first embodiment, the permanent magnet 8 embedded in the magnet insertion hole 7 is exemplified by a substantially rectangular shape as shown in FIG. 4, for example, but the permanent magnet 8 of the second embodiment is as shown in FIG. Of the three permanent magnets, the corners on the outer peripheral surface side of the permanent magnets 8a ′ and 8c ′ located on both ends are chamfered.

In general, when the motor generates rotor torque, the magnetic flux 13 flowing from a stator (not shown) is linked to the permanent magnet 8 (in FIG. 8, the permanent magnet 8a ′) located on the outermost peripheral side of the rotor core 6. To do. At this time, the interlinkage magnetic flux 13 is in a direction opposite to the magnetization direction of the permanent magnet 8a ', so that the permanent magnet 8 is demagnetized and the torque is reduced. As a result, the contribution to the rotor torque at the corner of the permanent magnet 8a 'is small. Therefore, if the corners of the permanent magnet 8 located on the outermost peripheral side of the rotor core 6 are chamfered, it is possible to effectively reduce the weight of the permanent magnet while suppressing a decrease in the rotor torque. Become.

Also, when the magnetic flux passes, an eddy current flows through the passing portion, so that the eddy current loss generated in the permanent magnet can be reduced by the chamfering.

Further, in the present embodiment, only the corners of the permanent magnet 8 positioned on the outermost peripheral side of the rotor core 6 are chamfered, and the magnet insertion hole 7 for inserting the permanent magnet 8 is described in the first embodiment. Therefore, the effect of the first embodiment for reducing the leakage magnetic flux can be maintained.

Embodiment 3 FIG.
FIG. 9 is a schematic cross-sectional view showing the structure of the rotor core according to the third embodiment of the present invention. FIG. 10 is a partially enlarged view of the magnet insertion hole shown in FIG. 9 and the effects of the third embodiment. It is a figure explaining. In the third embodiment, as shown in FIGS. 10A and 10B, the surface of the contact surface 14 which is a part of the contact surface with the permanent magnet 8 in the magnet insertion hole 7 is roughened. With such a structure of the contact surface 14, a frictional holding force against the centrifugal force generated in the permanent magnet 8 is obtained by the frictional force obtained by the contact between the permanent magnet 8 embedded in the magnet insertion hole 7 and the contact surface 14. And the permanent magnet can be easily held.

Embodiment 4 FIG.
FIG. 11 is a schematic cross-sectional view showing the structure of the rotor core according to the fourth embodiment of the present invention. In the first embodiment, the permanent magnet 8 embedded in the magnet insertion hole 7 is exemplified by a substantially rectangular shape as shown in FIG. 4, for example, but in the fourth embodiment, as shown in FIG. Among the permanent magnets, a substantially trapezoidal one is used as the permanent magnet 8d located at the center. The approximate trapezoidal shape here means that the contact surface of the permanent magnet 8 with the magnet insertion hole 7 is tapered so that the center portion side is wider than the outer peripheral portion side. .

Generally, centrifugal force increases when rotating at high speed or when the outer diameter of the rotor is large. For this reason, it is desired to increase the holding force of the central permanent magnet in which the influence of the centrifugal force appears most. Therefore, as shown in FIG. 11, if the shape of the permanent magnet 8d located at the center is a substantially trapezoidal shape, the permanent magnet 8d is embedded in the magnet insertion hole 7 in a wedge shape and resists centrifugal force. A force can be obtained by the structure of the rotor core 6 and the permanent magnet can be easily held.

In addition, in FIG. 11, although the structure which made only the permanent magnet located in the center part a substantially trapezoid shape among three permanent magnets was illustrated, considering the productivity of a permanent magnet, as shown in FIG. It is preferable that the permanent magnets 8f and 8g at both ends are also substantially trapezoidal. By making all the permanent magnets into a substantially trapezoidal shape, a bridge portion (see FIG. 4) formed between the permanent magnets and a bridge formed between the permanent magnets at both ends and the outer peripheral surface of the rotor core 6 are formed. The strength against centrifugal force at the portion (see FIG. 4) can be improved. As a result, the area (volume) of both the bridge portions can be further reduced, and the leakage flux and iron loss can be further reduced.

Embodiment 5 FIG.
FIG. 13: is a schematic cross section which shows the structure of the rotor core concerning Embodiment 5 of this invention. In the first embodiment, for example, the configuration of the rotor core having three permanent magnets per pole as shown in FIG. 4 is exemplified. However, in the rotor core of the fifth embodiment, as shown in FIG. A rotor core having four permanent magnets in combination with permanent magnets 8h and 8i having substantially rectangular shapes obtained by dividing a permanent magnet located in the central portion into two and having substantially rectangular shaped permanent magnets 8a and 8c located on both ends. It illustrates the structure.

FIG. 14 is a diagram comparing the maximum stress generated in the magnet insertion hole between the first embodiment and the fifth embodiment. In FIG. 14, the conventional example and the first embodiment are the same as those shown in FIG.

As shown in FIG. 14, if the maximum stress of the conventional example is “1”, the maximum stress of the fifth embodiment is 0.45, which is 55% lower than the conventional example. Even if compared with the first embodiment, there is a reduction effect of slightly less than 20% (1− (0.45 / 0.55) ≈0.19). Therefore, according to the rotor of the fifth embodiment, it is possible to obtain a further suppression effect of leakage magnetic flux generation while maintaining the strength against centrifugal force.

In the fifth embodiment, the permanent magnets 8h and 8i obtained by dividing the permanent magnet located in the central portion into two are illustrated as having a substantially rectangular shape as shown in FIG. 13, but FIG. 15 shows the permanent magnets 8j and 8k. As shown in the figure, the contact surface on the permanent magnet side located at both ends may be a substantially trapezoidal shape with a tapered shape, or the other contact surface may have a substantially trapezoidal shape with a tapered shape as shown in FIG. Absent.

Further, in the fifth embodiment, the permanent magnets 8a and 8c positioned at both ends are illustrated as having a substantially rectangular shape as shown in FIG. 13, but as shown as permanent magnets 8l and 8m in FIG. The permanent magnet positioned at the position may be substantially trapezoidal.

In the fifth embodiment, the configuration of the rotor core having four permanent magnets per pole obtained by dividing the permanent magnet located in the central portion into two parts is illustrated. However, the size of the permanent magnets located at both end portions is changed. Of course, it is possible.

Further, in the fifth embodiment, the configuration of the rotor core having four permanent magnets per pole is exemplified, but it is of course possible to have a configuration having five or more permanent magnets per pole.

Embodiment 6 FIG.
FIG. 17 is a schematic cross-sectional view showing the structure of the rotor core according to the sixth embodiment of the present invention. In the first embodiment, as the magnet insertion holes 7a to 7c, as shown in FIGS. 3 and 4, for example, when the permanent magnets 8a to 8c are inserted into the respective magnet insertion holes 7a to 7c, 2 Magnet insertion holes (magnet insertion holes 7b in the examples of FIGS. 3 and 4) located not only on both side surfaces of the magnet insertion holes (magnet insertion holes 7a and 7c in the examples of FIGS. 3 and 4) but also in the center. The thing which a cavity part is formed also in both the side surface parts of was illustrated. On the other hand, in the sixth embodiment, as shown in FIG. 17, an example in which cavities are formed only on both side surfaces of two magnet insertion holes 7 a and 7 c located at both ends is illustrated.

In the fourth embodiment, it will be described that the influence of centrifugal force appears more in the permanent magnet located in the center than the permanent magnet located in both ends, and the shape of the permanent magnet located in the center is substantially trapezoidal. An example was given (see FIG. 11). On the other hand, in this embodiment, as described above, the cavity is formed only on both side surfaces of the two magnet insertion holes 7a and 7c located at both ends, and the magnet insertion hole 7b located at the center. A configuration is adopted in which no hollow portion is formed on both side surface portions.

When the hollow portion is not provided, the contact area between the permanent magnet and the magnet insertion hole is increased, so that the effect of increasing the permanent magnet holding force can be obtained. On the other hand, the bridge portion 10a formed between the permanent magnets 8a and 8b and the bridge portion 10b formed between the permanent magnets 8b and 8c are widened, and the leakage magnetic flux passing between the bridge portions 10a and 10b is increased. There are concerns. However, in the configuration of FIG. 17, of the hollow portions formed in the two magnet insertion holes 7 a and 7 c located at both ends, the hollow portions 9 a 2 and 9 c 1 formed on the side surface portion on the center side are shown in FIG. Since the width of the bridge portions 10a and 10b can be reduced if it is formed larger than that of the above, the increase in leakage magnetic flux can be suppressed.

In the present embodiment, an example in which a configuration in which cavities are formed only on both side surfaces of the two magnet insertion holes 7a and 7c located at both ends is applied to the rotor core of the first embodiment. Although shown, it can also be applied to the rotor cores shown in the second to fifth embodiments, and the same effects as in the present embodiment can be obtained.

Embodiment 7 FIG.
FIG. 18 is a schematic cross-sectional view showing the structure of the rotor core according to the seventh embodiment of the present invention. In the present embodiment, as shown in FIG. 18, a spacer 21a is provided between the magnet insertion holes 7a and 7c located at both ends and the permanent magnets 8a and 8c inserted into the magnet insertion holes 7a and 7c. , 21c are provided and held. The spacers 21a and 21c are preferably non-magnetic materials in order to reduce the influence of the magnetic field on the rotor core.

In Embodiments 4 and 6, it has been explained that the influence of centrifugal force appears more in the permanent magnet located in the center than in the permanent magnet located at both ends. On the other hand, when the curvature of the curve connecting the generally U-shaped magnet insertion holes 7a to 7c in which the permanent magnets 8a to 8c are arranged is large (when the radius of curvature is small), the permanent magnets 8a, which are permanent magnets at both ends. In 8c, the difference between the magnetization direction (the direction orthogonal to the longitudinal direction of the magnet) and the direction of the centrifugal force becomes large, and a lateral (longitudinal) force acts on the permanent magnets 8a and 8c. In the permanent magnet 8b, which is a permanent magnet at the center, the magnetization direction and the direction of the centrifugal force substantially coincide with each other, and therefore the lateral force acting on the permanent magnet 8b is small.

As shown in FIG. 18, if spacers 21a and 21c are provided between the magnet insertion holes 7a and 7c and the permanent magnets 8a and 8c, respectively, the frictional force between the permanent magnets 8a and 8c and the spacers 21a and 21c. Since the centrifugal force acting in the longitudinal direction can be suppressed, the permanent magnet can be easily held.

Embodiment 8 FIG.
FIG. 19 is a schematic cross-sectional view showing the structure of the rotor core according to the eighth embodiment of the present invention. In FIG. 19, the unidirectional arrow lines attached to the permanent magnets 8a to 8c indicate the respective magnetization directions, and the thickness 31b in the magnetization direction of the permanent magnet 8b at the center is on both side surfaces. The permanent magnets 8a and 8c are smaller (thinner) than the thicknesses 31a and 31c in the magnetization direction. Here, when the magnetic flux (not shown) from the stator 2 is large, the magnetic flux is linked to the end of the permanent magnet on the side surface close to the rotor surface. Further, the smaller the thickness of the permanent magnet in the magnetizing direction, the smaller the magnetic resistance of the magnetic flux from the stator, so the permanent magnet is likely to be demagnetized. However, when the distance from the rotor surface is long like the permanent magnet 9b, the magnetic flux from the stator 2 is difficult to reach. For this reason, the permanent magnet 9b in the central portion is not easily demagnetized, and the thickness of the permanent magnet 9b in the magnetization direction can be reduced (thinned).

In addition, you may make it the permanent magnet with smaller coercive force than the permanent magnets 9a and 9c in a both-sides surface part, without making thickness of the permanent magnet 9b in the center part the magnetization direction thin. Generally, the residual magnetic flux density decreases as the permanent magnet coercive force is increased, and the residual magnetic flux density can be increased by reducing the coercive force. For this reason, if the magnet structure by Embodiment 8 is employ | adopted, weight reduction by the axial direction shortening of a rotor is possible. Moreover, since the unit price of the permanent magnet tends to be lower as the coercive force is smaller, it is possible to reduce the cost of the rotor and hence the cost of the rotating electrical machine.

Embodiment 9 FIG.
20 and 21 are axial sectional views of the permanent magnet according to the ninth embodiment of the present invention, and FIG. 20 shows a sectional structure in the rotor axial direction of the permanent magnets 8a and 8c on both side surfaces, FIG. 21 shows a cross-sectional structure of the permanent magnet 8b on the center side in the rotor axis direction. As shown in FIG. 20, the number of magnet divisions of the permanent magnets 8a and 8c on both side surfaces is, for example, 10, and the number of magnet divisions of the permanent magnet 8b on the center side is as shown in FIG. For example, five. This difference is related to the eddy current loss of the permanent magnet, and is because the eddy current loss of the permanent magnet is reduced by increasing the number of magnet divisions.

More specifically, the eddy current loss of the permanent magnet generated by the stator magnetic flux is larger in the permanent magnets 8a and 8c close to the rotor surface, so that it is necessary to increase the number of magnet divisions, but the permanent magnet 8b. In the permanent magnet 8b arranged at a position far from the rotor surface as described above, the magnet eddy current loss due to the stator magnetic flux is reduced, so that the number of magnet divisions can be reduced and the cost can be reduced.

Further, when arranging permanent magnets having different numbers of magnet divisions, it is preferable that the magnet shape of the permanent magnet 8a (8) and the magnet shape of the permanent magnet 8b are different as shown in FIG. If a permanent magnet with a small number of magnet divisions is inserted on both side surfaces, eddy current loss may increase. On the other hand, as shown in FIG. 19, when the sizes of the permanent magnet 8a (8c) and the permanent magnet 8b are made different from each other, there is no possibility of inserting them by mistake, so that the yield can be improved. effective.

As described above, the present invention is useful as a permanent magnet type rotating electrical machine that effectively suppresses generation of leakage magnetic flux while maintaining strength against centrifugal force, and a rotor thereof.

DESCRIPTION OF SYMBOLS 1 Permanent magnet type electric motor 2 Stator 3 Stator iron core 3a Slot 3b Teeth 4 Stator coil 5 Rotor 6 Rotor iron core 7, 7a-7c Magnet insertion hole 8, 8a-8m, 8a ', 8c', 16, 16a 16c Permanent magnet 9, 9a1, 9a2, 9b1, 9b2, 9c1, 9c2 Cavity part 10a, 10b, 11a, 11b Bridge part 12 Leakage magnetic flux 13 Magnetic flux 14 Contact surface 15 Core back part 18 Rotating air gap 21a, 21c Spacer 31a-31c Thickness in the magnetization direction

Claims (13)

A stator that houses a stator coil inside the slot;
A rotor having a rotor core disposed rotatably in the stator via a rotation gap, and three or more permanent magnets embedded in each rotor core;
With
The rotor core is provided with magnet insertion holes for embedding the permanent magnets arranged in a substantially U shape toward the outer peripheral surface of the rotor, and at least the rotation of the permanent magnets embedded in the magnet insertion holes. A permanent magnet type rotating electrical machine characterized in that cavities are formed on both side surfaces of two permanent magnets per pole located on the outermost peripheral side of the core. 2. The permanent magnet type rotating electric machine according to claim 1, wherein a hollow portion is also formed on both side portions of the permanent magnet located on the central portion side of the rotor core. The rotor core is attached to a first permanent magnet set magnetized in a direction that converges toward the outer peripheral surface of the rotor and a direction that extends concentrically toward the center of the rotor. The permanent magnet type rotating electric machine according to claim 2, wherein the magnetized second permanent magnet groups are alternately arranged. The permanent magnet type according to claim 2, wherein the magnet insertion hole is larger in the magnet insertion hole located on the outermost peripheral side of the rotor core than in the other magnet insertion holes. Rotating electric machine. In two magnet insertion holes per pole located on the outermost peripheral side of the rotor core,
The size of the cavity formed when the permanent magnets are embedded in these magnet insertion holes is such that the cavity formed on the outer peripheral side is larger than the cavity formed on the center side. The permanent magnet type rotating electrical machine according to claim 2, The permanent magnet type rotating electric machine according to claim 2, wherein corners on the outer peripheral surface side of two permanent magnets per pole located on the outermost peripheral side of the rotor core are chamfered. The permanent magnet type rotating electric machine according to claim 2, wherein a part of a contact surface between the magnet insertion hole and the permanent magnet is roughened. The permanent magnet type rotating electric machine according to claim 2, wherein the permanent magnet has a tapered shape in which a contact surface with the magnet insertion hole becomes wider toward a central portion of the rotor core. 3. The permanent magnet type rotating electric machine according to claim 2, wherein two permanent magnets per pole located on the outermost peripheral side of the rotor core are fixed by a spacer of a nonmagnetic member. 3. The permanent magnet according to claim 2, wherein the permanent magnet located on the center side of the rotor core has a smaller magnetization direction thickness than the permanent magnet located on the outermost peripheral side of the rotor core. Magnet type rotating electrical machine. 11. The permanent magnet according to claim 2, wherein the permanent magnet positioned on the central portion side of the rotor core has a smaller holding force than the permanent magnet positioned on the outermost peripheral portion side of the rotor core. Type rotating electric machine. 3. The permanent magnet type rotating electric machine according to claim 2, wherein each permanent magnet is divided in the axial direction of the rotor. The permanent magnet according to claim 12, wherein the number of divisions of the permanent magnet located on the center side of the rotor core is smaller than the number of divisions of the permanent magnet located on the outermost peripheral side of the rotor core. Magnet type rotating electrical machine.

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