WO2013065110A1

WO2013065110A1 - Interior permanent magnet motor and compressor

Info

Publication number: WO2013065110A1
Application number: PCT/JP2011/075103
Authority: WO
Inventors: 昌弘仁吾; 馬場　和彦; 和慶土田
Original assignee: 三菱電機株式会社
Priority date: 2011-10-31
Filing date: 2011-10-31
Publication date: 2013-05-10
Also published as: JPWO2013065110A1; JP5755338B2; CN103891103A; CN103891103B

Abstract

This interior permanent magnet motor is constructed by installing a rotor core (7), which is created by laminating multiple electromagnetic steel plates together, inside a stator. Magnets that constitute magnetic poles of the rotor core (7) comprise: ferrite magnets (4) which are provided on the outer periphery side of the rotor core (7) in the circumferential direction of the rotor core (7) only in a number corresponding to the number of the poles; and rare-earth magnets (3) which are provided between the ferrite magnets (4). Each of the ferrite magnets (4) is arranged such that the center of the ferrite magnet (4) is placed at an inter-polar position (20) between the magnetic poles (21), and is magnetized such that the magnetization direction is changed at the inter-polar position (20).

Description

Permanent magnet embedded electric motor and compressor

The present invention relates to a permanent magnet embedded motor and a compressor equipped with this motor.

In a general embedded permanent magnet electric motor, either a ferrite magnet or a rare earth magnet is adopted as a permanent magnet constituting the magnetic pole of the rotor. When a ferrite magnet is used, it is inexpensive and various shapes of permanent magnets can be obtained with ease of molding. However, since the magnetic flux density is small, it is difficult to reduce the size of the motor. On the other hand, when a rare earth magnet is used, it is easy to miniaturize the motor because the magnetic flux density is large, but it is expensive and the shape of the permanent magnet is limited due to the difficulty of molding. Therefore, the conventional general permanent magnet embedded type electric motor employs either a ferrite magnet or a rare earth magnet in consideration of the use and cost of the motor, and therefore there is a trade-off relationship between the magnetic flux density and the cost. There was a problem that there was.

In order to solve such a problem, in the prior art disclosed in Patent Document 1 below, the magnets constituting the field magnetic poles are arranged in a number corresponding to the number of poles in the rotor rotation direction along the circumference of the rotor core inner diameter. A rare earth magnet and a ferrite magnet arranged along the boundary between the magnetic poles of the rare earth magnet are included. Each of the magnetic poles is composed of at least three permanent magnets using the ferrite magnet as a shared adjacent magnetic pole. An effect of reducing the cost is shown by using an expensive rare earth magnet and an inexpensive ferrite magnet in combination.

Japanese Patent No. 3832530 (FIG. 1 etc.)

However, in the prior art disclosed in Patent Document 1, the rare earth magnet is arranged closer to the shaft center hole than the ferrite magnet in order to prevent both magnets from becoming magnetic resistance on each other's magnetic circuit. Therefore, the amount of the iron core on the magnetic pole surface of the rotor, that is, the iron core area between the rare earth magnet and the rotor outer peripheral surface is larger than when the rare earth magnet and the ferrite magnet are arranged on the same circumference. The magnetic attraction force (rotating direction in the radial direction of the rotor) increases in proportion to the noise and the sound and vibration increase.

The present invention has been made in view of the above, and an object thereof is to obtain an embedded permanent magnet electric motor and a compressor capable of reducing sound and vibration.

In order to solve the above-described problems and achieve the object, the present invention is a permanent magnet embedded electric motor in which a rotor core formed by laminating a plurality of electromagnetic steel plates is disposed in a stator, Magnets constituting the magnetic poles of the rotor core are provided between the ferrite magnets and ferrite magnets provided on the outer peripheral side of the rotor core and arranged in a number corresponding to the number of poles in the circumferential direction of the rotor core. The ferrite magnet is disposed so that the center of the ferrite magnet is located between the poles of the magnetic pole, and is magnetized so that the magnetization direction is reversed with respect to the gap between the poles. It is characterized by.

According to the present invention, there is an effect that sound and vibration can be reduced.

FIG. 1 is a cross-sectional view of an embedded permanent magnet electric motor according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing the structure of the rotor shown in FIG. FIG. 3 is a cross-sectional view centering on the magnet insertion hole. FIG. 4 is a cross-sectional view of a rotor using a ferrite magnet whose magnetization direction is radially oriented. FIG. 5 is a cross-sectional view for explaining the relationship between the magnetic circuit of the ferrite magnet and the magnetic circuit of the rare earth magnet shown in FIG. FIG. 6 is a cross-sectional view of a rotor using a ferrite magnet in which the magnetization direction of the magnet is parallel. FIG. 7 is a cross-sectional view of a rotor using a ferrite magnet in which the magnetization direction of the magnet is polar. FIG. 8 is a cross-sectional view of a conventional permanent magnet embedded electric motor using only rare earth magnets. FIG. 9 is a diagram for explaining the relationship between the thickness and width of the ferrite magnet. FIG. 10 is a diagram for explaining the relationship between the magnetic pole opening of the rare earth magnet and the tooth width.

Hereinafter, embodiments of an embedded permanent magnet electric motor and a compressor according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment.
FIG. 1 is a cross-sectional view of an embedded permanent magnet electric motor (hereinafter referred to as “motor”) 100 according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view showing the structure of the rotor 1 shown in FIG. It is. FIG. 3 is a cross-sectional view centering on the magnet insertion hole, FIG. 4 is a cross-sectional view of the rotor 1 using the ferrite magnet 4 having a radial magnetization direction, and FIG. 5 is a ferrite shown in FIG. FIG. 6 is a cross-sectional view for explaining the relationship between the magnetic circuit of the magnet 4 and the magnetic circuit of the rare earth magnet 3, and FIG. 6 is a cross-sectional view of the rotor 1 using the ferrite magnet 4 in which the magnetization direction of the magnet is parallel. FIG. 7 is a cross-sectional view of the rotor 1 using the ferrite magnet 4 in which the magnetization direction of the magnet is polar.

In FIG. 1, an electric motor 100 according to an embodiment of the present invention includes a stator 2 and a rotor 1. A plurality of teeth are formed at equiangular pitches in the circumferential direction on the inner peripheral portion of the stator 2.

In FIG. 2, the rotor 1 includes a magnet embedded rotor core 7, a rare earth magnet 3, and a ferrite magnet 4 as main components. In FIG. 2, as an example, the shaft hole side surface 4 a of the ferrite magnet 4 is arranged on the same circumference as the shaft hole side surface 3 a of the rare earth magnet 3.

The rotor core 7 is manufactured by laminating electromagnetic steel plates, and the outer peripheral surface of the rotor is formed in a cylindrical shape. The rotor core 7 includes, for example, six magnetic poles 21, and each magnetic pole 21 is composed of one Nd—Fe—B rare earth magnet 3. And one side of the two ferrite magnets 4.

The ferrite magnet 4 has a plate shape in which the shaft hole side surface 4a is formed in a substantially arc shape. The rare earth magnet 3 has a flat plate shape magnetized in parallel in the thickness direction (radial direction of the rotor 1). The residual magnetic flux density of the Nd—Fe—B rare earth magnet 3 is about three times the residual magnetic flux density of the wet ferrite magnet 4. The thickness of the rare earth magnet 3 is formed thinner than the thickness of the ferrite magnet 4. In the rotor 1 of the present embodiment, for example, the thickness of the rare earth magnet 3 is about 2 mm and the thickness of the ferrite magnet 4 is about 4 mm. .

A shaft hole 8 for connecting a shaft (not shown) for transmitting rotational energy and the rotor core 7 is provided at the center of the rotor 1. The rotor core 7 and the shaft are connected by shrink fitting, press fitting, or the like. A hole 9 is provided between the shaft hole 8 and the magnets (3, 4) for allowing refrigerant and refrigerating machine oil to pass through.

In FIG. 3, a ferrite magnet insertion hole 22 formed between the shaft hole 8 and the rotor outer peripheral surface by the number corresponding to the number of poles in the rotor rotation direction on the rotor outer peripheral surface side. A rare earth magnet insertion hole 23 formed on the same circumference as the ferrite magnet insertion hole 22 is provided therebetween. The rare earth magnet 3 is accommodated in the rare earth magnet insertion hole 23, and the ferrite magnet 4 is accommodated in the ferrite magnet insertion hole 22. In the following description, the ferrite magnet insertion hole 22 is referred to as the insertion hole 22, and the rare earth magnet insertion hole 23 is referred to as the insertion hole 23.

Between the insertion hole 22 and the insertion hole 23, an inter-magnet thin portion 14 is provided, and between the insertion hole 22 and the rotor outer peripheral surface, a ferrite magnet outer peripheral thin portion 15 is provided. The thicknesses of the inter-magnet thin portion 14 and the ferrite magnet outer peripheral thin portion 15 are, for example, 0.35 mm, which is about the same as the thickness of the electromagnetic steel plate (not shown) forming the rotor core 7. In the following description, the inter-magnet thin portion 14 is referred to as a thin portion 14, and the ferrite magnet outer peripheral thin portion 15 is referred to as a thin portion 15.

2 is formed between the ferrite magnet 4 and the thin wall portion 15 shown in FIG. This air hole 19 is formed by cutting the rotor outer peripheral surface side of the insertion hole 22, for example.

On the rotor outer peripheral surface side of the rare earth magnet 3, there is an iron core portion 7 a formed to be thicker than the thin portion 15. That is, in the rotor 1 of the present embodiment, the iron core area between the rare earth magnet 3 and the rotor outer peripheral surface (the thickness of the iron core portion 7a) is the same as the iron core area between the insertion hole 22 and the rotor outer peripheral surface (of the thin portion 15). It is configured to be larger than (thickness).

The iron core portion 7a is provided with a slit 6 for relaxing magnetic flux density imbalance and magnetic saliency.

2 represents a boundary line where adjacent magnetic poles 21 (N pole and S pole) are switched. The rare earth magnet 3 is disposed at the center of the magnetic pole 21, and the ferrite magnet 4 is disposed between the poles 20. It arrange | positions so that the center of the ferrite magnet 4 may be located. The ferrite magnet 4 disposed between the poles 20 is composed of at least one, and is magnetized so that the magnetization direction is reversed with respect to the poles 20. Hereinafter, the magnetization direction will be described.

In FIG. 4, the magnetization direction of the rare earth magnet 3 is parallel, and the magnetization direction of the ferrite magnet 4 is radial orientation. The magnetization direction of the ferrite magnet 4 is magnetized so as to be reversed between the poles 20. FIG. 4 shows a focal point 17 having a radial orientation as a position where the magnetization direction is reversed. The magnetization direction of the ferrite magnet 4 is substantially the same as the direction of the rare earth magnet 3 with the inter-electrode 20 as a boundary.

Here, in the case where the rare earth magnet 3 and the ferrite magnet 4 are used in combination, when both magnets are arranged so as to have a magnetic resistance on the magnetic circuit of the other magnet, the effective magnetic flux amount linked to the stator 2 is reduced. This is not preferable. For example, when the magnetization direction of the ferrite magnet 4 is perpendicular to the gap 20, the rare earth magnet 3 exists in the magnetization direction of the ferrite magnet 4. Therefore, the rare earth magnet 3 becomes a magnetic resistance when viewed from the ferrite magnet 4, and the magnetic flux of the ferrite magnet 4 cannot be used effectively. In the above prior art, the rare earth magnet 3 is arranged on the inner peripheral side (the shaft hole 8 side) of the ferrite magnet 4 in order to effectively use the magnetic flux of the ferrite magnet 4.

On the other hand, when the magnetization direction of the ferrite magnet 4 is parallel, radial, or polar, the rare earth magnet 3 and the ferrite magnet 4 are unlikely to have a magnetic resistance on each other's magnetic circuit. FIG. 5 schematically shows a magnetic circuit (flow of magnetic flux) by the rare earth magnet 3 disposed on the rotor 1 and a magnetic circuit by the ferrite magnet 4. The magnetic flux generated from each magnet constitutes a magnetic circuit as indicated by a broken line through the stator 2 shown in FIG. The rotor 1 according to the present embodiment is a parallel circuit in which both magnetic circuits do not interfere with each other. Therefore, the rotor 1 can make maximum use of the magnetic flux of the rare earth magnet 3 and the ferrite magnet 4.

Further, when compared with the conventional electric motor using only the rare earth magnet 3 with the same rotor magnetic flux, the rotor 1 of the present embodiment can reduce the amount of the rare earth magnet 3 for the magnetic flux supplement by the ferrite magnet 4. it can.

The magnetic flux of the ferrite magnet 4 is easily short-circuited because the magnetization direction is switched between the poles 20. However, in order to reduce the short-circuit magnetic flux, the magnetization direction of the ferrite magnet 4 is nearly perpendicular to the gap 20 ( It is preferably oriented in a direction that is not completely vertical.

Therefore, in the rotor 1 according to the present embodiment, the effective magnetic flux linked to the stator 2 is obtained by setting the magnetization direction of the ferrite magnet 4 to the radial orientation as shown in FIG. 4 or the polar orientation as shown in FIG. Is increasing. The magnetization direction of the ferrite magnet 4 is not limited to the radial orientation and the polar orientation, and may be a parallel orientation as shown in FIG. In this case, although the amount of effective magnetic flux linked to the stator 2 is lower than that in the case of radial orientation or polar orientation, it is possible to avoid the above-described configuration of the magnetic resistance.

FIG. 8 is a cross-sectional view of a conventional permanent magnet embedded electric motor 110 using only the rare earth magnet 3. The conventional permanent magnet embedded motor 110 has a problem that the short-circuit magnetic flux between the adjacent rare earth magnets 3 (adjacent N pole and S pole) is large. More specifically, for example, when the magnetic flux emitted from the magnetic pole 21 shown in FIG. 2 is linked to the coil of the stator 2 shown in FIG. 1, this magnetic flux is effectively used as the magnet torque. However, when the magnetic flux emitted from the magnetic pole 21 is short-circuited without passing through the coil of the stator 2, this magnetic flux cannot be used as magnet torque.

As shown in FIG. 2, the rotor 1 according to the present embodiment includes a ferrite magnet 4 having a large magnetic resistance between adjacent rare earth magnets 3. . As a result, the amount of effective magnetic flux linked to the stator 2 can be increased.

The short circuit of the magnetic flux between the adjacent rare earth magnets 3 tries to pass through the thin portion 15 shown in FIG. In the rotor 1 of the present embodiment, since the ferrite magnet 4 is arranged on the rotor outer peripheral surface side, the thin portion 15 is thinned, and the magnet outer peripheral thin wall of the permanent magnet embedded electric motor 110 of the single rare earth magnet 3 is thin. The magnetic resistance can be made larger than that of the thin portion 15a. Moreover, since the thin part 15 of this Embodiment is magnetically saturated with the magnetic flux of the ferrite magnet 4, it becomes difficult to produce a short circuit magnetic flux. As a result, the amount of effective magnetic flux linked to the stator 2 can be increased.

Further, when the rare earth magnet 3 and the ferrite magnet 4 are used in combination, a thin portion 14 as shown in FIG. 2 is required, but this thin portion 14 creates a short-circuit path of magnetic flux from the front to the back of the magnet, and the stator. The effective magnetic flux amount linked to 2 is reduced. In the rotor 1 of the present embodiment, since the rare earth magnet 3 and the ferrite magnet 4 are arranged on the same circumference and the thin portion 14 is further thinned, the magnetic flux of the rare earth magnet 3 and the magnetic flux of the ferrite magnet 4 are However, since the thin part 14 is short-circuited (short-circuited from the front to the back of the magnet), the thin part 14 is easily magnetically saturated. Accordingly, the amount of short-circuit magnetic flux can be reduced as compared with the case where the rare earth magnet 3 alone or the ferrite magnet 4 alone is configured. As a result, the amount of effective magnetic flux linked to the stator 2 can be increased.

Also, in the electric motor 100, the iron core on the surface of the magnetic pole 21 causes an increase in sound and vibration associated with the magnetic attraction force when the rotor 1 is eccentric. Therefore, a design that reduces the iron core area on the surface of the magnetic pole 21 is preferable. In the rotor 1 according to the present embodiment, the rare earth magnet 3 and the ferrite magnet 4 are arranged on the same circumference, so that the area of the iron core portion 7a existing on the rotor outer circumferential surface side of the rare earth magnet 3 can be reduced. . Therefore, it is possible to reduce the sound and vibration described above.

Further, the residual magnetic flux density of the rare earth magnet 3 is about three times that of the ferrite magnet 4. Therefore, when the rare earth magnet 3 and the ferrite magnet 4 are used in combination, the energy change amount of the magnetic flux density at the boundary surface between the rare earth magnet 3 and the ferrite magnet 4 on the outer peripheral surface of the rotor is large, and this energy change increases sound and vibration. Cause. The rotor 1 of the present embodiment is configured such that the iron core portion 7 a existing on the rotor outer peripheral surface side of the rare earth magnet 3 is larger than the iron core (thin wall portion 15) existing on the rotor outer peripheral surface side of the ferrite magnet 4. Yes. Therefore, the concentration of the magnetic flux density on the surface of the rare earth magnet 3 having a high magnetic flux density is alleviated, and the amount of energy change of the magnetic flux density described above becomes small. As a result, the electric motor 100 with low sound and vibration can be realized.

In addition, when the slit 6 is provided in the iron core part 7a on the surface of the rare earth magnet 3, the magnetic attraction force can be reduced while relaxing the energy change of the magnetic flux density described above by adjusting the width and position of the slit 6, and sound and It is effective in reducing vibration.

Also, by arranging the rare earth magnet 3 and the ferrite magnet 4 on the same circumference, it is possible to secure a wide space in the inner circumference of the rotor 1 having a small influence on the magnetic characteristics. Therefore, it is easy to provide caulking and air holes (holes 9) in this space, and the manufacturability and cooling performance of the rotor 1 can be improved. In the case of a compressor in which refrigerant or oil passes through the electric motor, the circulation amount of the refrigerant or oil is increased by opening the holes 9, and the effect of performance improvement is great.

In the rotor 1 of the present embodiment, an air hole 19 is formed between the ferrite magnet 4 and the thin portion 15. By providing the air holes 19, the following effects can be obtained. When a current having a demagnetization phase is passed through the stator 2, a magnetic field (demagnetizing field) in a direction opposite to the magnetization direction of the magnet is generated. The demagnetizing field with respect to the rare earth magnet 3 escapes through the thin portion 14 because the rare earth magnet 3 is somewhat embedded in the shaft hole 8 side. However, the demagnetizing field with respect to the ferrite magnet 4 is easy to demagnetize the ferrite magnet 4 because the ferrite magnet 4 is disposed in the vicinity of the rotor outer peripheral surface. Therefore, in the rotor 1 of the present embodiment, by providing the air hole 19 on the rotor outer peripheral surface side of the ferrite magnet 4, the ferrite magnet 4 becomes difficult to demagnetize, and the reliability of the rotor 1 against demagnetization is improved. Can do.

FIG. 9 is a diagram for explaining the relationship between the thickness and the width of the ferrite magnet 4. The ferrite magnet 4 shown in FIG. 9 is such that W> T, where T is the thickness in the magnetization direction (length in the radial direction) and W is the width (length in the rotation direction) of the ferrite magnet 4. It is configured.

In the electric motor 100 according to the present embodiment, since the ferrite magnet 4 having a large magnetic resistance exists between the adjacent rare earth magnets 3, the magnetic flux of the rare earth magnet 3 becomes difficult to be short-circuited, and the effective magnetic flux amount linked to the stator 2 is reduced. Can be increased. And since the magnetic resistance between the adjacent rare earth magnets 3 can be increased as the width W of the ferrite magnet 4 is increased, the effect of reducing the short-circuit magnetic flux can be enhanced by configuring W> T. Is possible. Further, the smaller the thickness T, the closer the rare earth magnet 3 can be to the vicinity of the rotor outer peripheral surface, so that the iron core area (thickness of the iron core portion 7a) between the rare earth magnet 3 and the rotor outer peripheral surface can be reduced. Can be further reduced.

FIG. 10 is a diagram for explaining the relationship between the magnetic pole opening A and the teeth width B of the rare earth magnet 3. The electric motor 100 shown in FIG. 10 has a tooth width of the teeth 18 (the end face of the teeth 18 facing the outer peripheral surface of the rotor), where A is the width of the magnetic pole opening on the surface of the rare earth magnet 3 (the length between adjacent ferrite magnets 4). When B is (width), B> A.

In the rotor 120 of the rare earth magnet 3 alone as shown in FIG. 8, in order to effectively use the magnet space of the rotor 120, the rare earth magnet 3 is widely arranged on the rotor surface, and the magnetic pole on the surface of the rare earth magnet 3 is larger than the teeth width B. In many cases, the width of the opening (corresponding to the width A) is wide. In that case, the magnetic flux of the rare earth magnet 3 is easily short-circuited to the adjacent magnet through the teeth 18.

The electric motor 100 of the present embodiment can be configured to reduce the width A of the magnetic pole opening on the surface of the rare earth magnet 3 by using the rare earth magnet 3 and the ferrite magnet 4 in combination. Therefore, it is possible to prevent the magnetic flux of the rare earth magnet 3 having a width A smaller than the tooth width B and having a high magnetic flux density from being short-circuited to the adjacent rare earth magnet 3 through the teeth 18. It is possible to obtain. In particular, in the electric motor 100 of the present embodiment, since the rare earth magnet 3 is surrounded by the ferrite magnet 4 having a large magnetic resistance, by configuring the width A to be smaller than the teeth width B, the magnetic flux of the rare earth magnet 3 is It becomes easy to flow to the teeth 18 having a small magnetic resistance.

In the present embodiment, the configuration example in which the shaft hole side surface 4a of the ferrite magnet 4 and the shaft hole side surface 3a of the rare earth magnet 3 are arranged on the same circumference has been described. For example, the rare earth magnet 3 is replaced with the ferrite magnet 4 Alternatively, the rare earth magnet 3 may be disposed closer to the slit 6 than the shaft hole 8.

As described above, the electric motor 100 according to the present embodiment includes a permanent magnet embedded in which a rotor core (rotor core 7) formed by laminating a plurality of electromagnetic steel plates is disposed in a stator (stator 2). The magnet constituting the magnetic pole 21 of the rotor core 7 is a ferrite magnet 4 provided on the outer peripheral side of the rotor core 7 and arranged in a number corresponding to the number of poles in the circumferential direction of the rotor core 7, and the ferrite magnet 4 The ferrite magnet 4 is arranged so that the center of the ferrite magnet 4 is located between the poles 20 of the magnetic pole 21, and the magnetization direction is reversed with respect to the poles 20. Thus, the magnetic circuit of both the rare earth magnet 3 and the ferrite magnet 4 is a parallel circuit that does not interfere with each other, and the magnetic flux of the rare earth magnet 3 and the ferrite magnet 4 is It is possible to take full advantage. Further, when compared with the conventional electric motor using only the rare earth magnet 3 with the same rotor magnetic flux, the rotor 1 of the present embodiment can reduce the amount of the rare earth magnet 3 for the magnetic flux supplement by the ferrite magnet 4. it can. As a result, the area of the iron core portion 7a existing on the rotor outer peripheral surface side of the rare earth magnet 3 can be reduced, and cost reduction, high efficiency, low noise, and low vibration can be realized.

Further, in the electric motor 100 according to the present embodiment, since the ferrite magnet 4 having a large magnetic resistance exists between the rare earth magnets 3, the magnetic flux between the adjacent rare earth magnets 3 is difficult to be short-circuited, and the front and back of the magnets are reversed. Short-circuit magnetic flux is hardly generated. Therefore, when considering the rare earth magnet 3 per unit volume, the effective magnetic flux amount linked to the stator 2 is increased, the magnet torque is increased, the applied current can be reduced, and the output can be increased. It is also possible to direct the increased amount of magnetic flux to reduce the amount of rare earth magnets.

In addition, since the ferrite magnet 4 according to the present embodiment is configured such that the magnetization direction is parallel orientation, radial orientation, or polar orientation, the rare earth magnet 3 does not become magnetoresistive when viewed from the ferrite magnet 4, In particular, in the case of radial orientation or polar orientation, the magnetization direction of the ferrite magnet 4 is oriented in a direction nearly perpendicular to the gap 20, so that the amount of effective magnetic flux linked to the stator 2 can be increased. Therefore, when compared with the conventional motor using only the rare earth magnet 3 with the same rotor magnetic flux, the amount of the rare earth magnet 3 for the magnetic flux supplement by the ferrite magnet 4 can be reduced, and the cost can be further reduced. High efficiency can be achieved.

Further, since the rare earth magnet 3 according to the present embodiment is arranged on the same circumference as the ferrite magnet 4, the iron core portion that is the cause of increasing the sound and vibration associated with the magnetic attraction force when the rotor 1 is eccentric. The area of 7a can be reduced. Therefore, compared with the case where the rare earth magnet 3 is not arranged on the same circumference as the ferrite magnet 4, it is possible to reduce noise and vibration.

In addition, the rotor core 7 according to the present embodiment is formed with an insertion hole 22 that is provided on the outer peripheral side of the rotor core 7 and into which the ferrite magnet 4 is inserted, and there is a gap between the outer peripheral surface of the ferrite magnet 4 and the insertion hole 22. Since the (air hole 19) is formed, it is possible to eliminate a portion that is easily demagnetized at the design stage, to prevent a change in the amount of magnetic flux due to demagnetization, and to improve the reliability. It is possible to improve the quality of the finished product.

The ferrite magnet 4 according to the present embodiment is configured such that W> T, where T is the thickness in the radial direction of the rotor core 7 and W is the length in the rotational direction of the rotor core 7. Therefore, the magnetic resistance between the rare earth magnets 3 is increased as W is increased, and the effect of reducing the short-circuit magnetic flux can be enhanced. Further, as T is smaller, the shaft hole side surface 4a can be closer to the rotor outer peripheral surface, and the shaft hole side surface 3a can be closer to the rotor outer peripheral surface accordingly. The iron core area (thickness of the iron core portion 7a) can be reduced, and sound and vibration can be further reduced.

A plurality of teeth 18 formed at intervals in the circumferential direction are formed on the inner peripheral side of the stator 2 according to the present embodiment, and the width of the magnetic pole opening on the surface of the rare earth magnet 3 is A. When the width of the teeth 18 is B, since B> A, the magnetic flux of the rare earth magnet 3 can be prevented from being short-circuited to the adjacent rare earth magnet 3 through the teeth 18. It is possible to obtain the electric motor 100 having a high magnetic flux utilization rate.

Further, when the electric motor 100 according to the present embodiment is used in a compressor such as an air conditioner, the circulation amount of the refrigerant and oil increases, and the performance can be improved.

Note that the permanent magnet embedded electric motor and the compressor according to the embodiment of the present invention show an example of the content of the present invention, and can be combined with another known technique. Of course, it is possible to change and configure such as omitting a part without departing from the gist of the present invention.

As described above, the present invention can be applied to a permanent magnet embedded electric motor and a compressor, and is particularly useful as an invention capable of reducing sound and vibration.

1, 120 rotor 2 stator (stator)
3

Rare earth magnet

3a, 4a Shaft hole side surface 4 Ferrite magnet 6 Slit 7 Rotor core (rotor core)
7a Iron core portion 8 Shaft hole 9 Hole 14 Thin portion between magnets 15 Ferrite magnet outer thin portion 15a Magnet outer thin portion 17 Focal point of radial orientation 18 Teeth 19 Air hole (gap)
20 Between poles 21 Magnetic pole 22 Ferrite magnet insertion hole 23 Rare earth

magnet insertion hole

100, 110 Permanent magnet embedded type electric motor

Claims

A permanent magnet embedded electric motor in which a rotor core formed by laminating a plurality of electromagnetic steel sheets is arranged in a stator,
The magnet constituting the magnetic pole of the rotor core is
A ferrite magnet provided on the outer peripheral side of the rotor core and disposed in a number corresponding to the number of poles in the circumferential direction of the rotor core, and a rare earth magnet disposed between the ferrite magnets,
The ferrite magnet is
A permanent magnet embedded type electric motor, wherein the ferrite magnet is disposed so that a center of the ferrite magnet is located between poles of the magnetic pole, and is magnetized so that a magnetization direction is reversed with respect to the gap between the poles.
The embedded permanent magnet electric motor according to claim 1, wherein the magnetization direction of the ferrite magnet is parallel, radial, or polar.
2. The embedded permanent magnet motor according to claim 1, wherein the rare earth magnet is disposed on the same circumference as the ferrite magnet.
The rotor core is provided with an insertion hole for inserting the ferrite magnet provided on the outer peripheral side of the rotor core,
The embedded permanent magnet motor according to claim 1, wherein a gap is formed between an outer peripheral surface of the ferrite magnet and the insertion hole.
The ferrite magnet is configured such that W> T, where T is the thickness in the radial direction of the rotor core and W is the length in the rotational direction of the rotor core. The embedded permanent magnet electric motor according to claim 1.
A plurality of teeth formed at intervals in the circumferential direction are formed on the inner peripheral side of the stator,
2. The permanent magnet embedding according to claim 1, wherein B is greater than A when the width of the magnetic pole opening on the surface of the rare earth magnet is A and the width of the teeth is B. 3. Type electric motor.
A compressor equipped with the interior permanent magnet motor according to claim 1.