WO2002027893A1

WO2002027893A1 - Rotor of electric motor

Info

Publication number: WO2002027893A1
Application number: PCT/JP2001/007916
Authority: WO
Inventors: Toshihiko Futami; Yoshiaki Inaba; Kiyotaka Kawamura
Original assignee: Toshiba Carrier Corporation
Priority date: 2000-09-25
Filing date: 2001-09-12
Publication date: 2002-04-04
Also published as: JP2002101586A; CN1466805A; KR20030034208A; AU2001286203A1

Abstract

A rotor of an electric motor, comprising a rotor core (5) formed integrally by stacking a plurality of steel sheets (1), a plurality of punched-out holes (6) passed through the rotor core adjacently to each other and along the outer periphery of the rotor core (5), and permanent magnets (7) fitted into the punched-out holes and integrally fixed to the rotor core (5), wherein the width dimensions of bridge parts (10) formed between the end edge of the punched-out holes and the peripheral surface of the rotor core (5) are set so that the width dimension (W2) of the bridge part (10a) on the rotating direction side is larger than that (W1) of the bridge part (10b) on the anti-rotating direction side (W1 < W2) at the end parts of the punched-out holes adjacent to each other, whereby an increase in leaked magnetic flux due to an increase in the width dimension of the bridge part can be suppressed to prevent the characteristics of the motor from deteriorating.

Description

Specification

Motor rotor

Technical field

The present invention relates to a rotor of an electric motor in which a permanent magnet is fitted into a rotor core. , Background technology

It is a well-known fact that Japan's household power consumption has grown remarkably in recent years. Above all, the proportion occupied by air conditioners (air conditioners) cannot be ignored, and this growth rate exceeds the increase in household power consumption.

For this reason, there is a growing demand for energy saving of air conditioners that responds to power demand and global environmental issues, and the development of air conditioners that generally require about half the electricity cost is being realized. .

One of the concrete means is to improve the compressor that forms the refrigeration cycle. Furthermore, a brushless DC motor (electric motor) driven by digital control is used as the drive source of the compression mechanism.

Figure 6 shows the cross-sectional shape of the rotor of a motor, which is a brushless DC motor, conventionally developed based on the above circumstances.

The rotor core b is formed by laminating a plurality of thin steel plates a, and a plurality of punched holes penetrated through the rotor core and provided adjacent to each other along the outer periphery of the rotor core. and a permanent magnet d fitted into these punched holes and fixed integrally to the rotor core b.

The rotor core b is provided with a shaft hole e at the center thereof. The center iron core f is defined between the periphery of the shaft hole and the inner periphery of the permanent magnet d, the magnetic pole core h is defined between the outer periphery of each permanent magnet d and the peripheral surface of the rotor core b, and the end of the punched hole c. The portion between the edge of the rotor core and the peripheral surface of the rotor core b is called a bridge portion i. The bridge i connects the center core f and the magnetic pole h.

By forming the permanent magnet d in an inverted arc shape, the flow of magnetic flux is smooth, and the harmonics are higher than in the previous structure in which the rotor jacket is covered with a stainless steel can. Eddy current loss caused by wave magnetic flux has been reduced, and efficiency has been improved.

As shown in FIG. 7, another conventional rotor has a straight permanent magnet d 1 fitted into a plurality of straight punched holes c 1 provided in a rotor core b 1, and a central shaft hole e. The same applies to the center iron core f1 between one circumference and the inner circumference of the permanent magnet d1, and the magnetic pole core h1 between the outer circumference of each permanent magnet d1 and the circumference of the rotor core b1.

In this example, flat holes g, which are holes, are continuously provided at both ends of each punched hole c1 to prevent short-circuiting of magnetic flux. The portion between the edge and the peripheral surface of the rotor core b1 is referred to as a bridge portion i1.

However, the rotor having any of the configurations shown in FIGS. 6 and 7 has the following problems.

That is, the bridge portions i and i1 connect the central cores f and f1 with the magnetic pole cores h and h1, and the centrifugal force of the magnetic pole cores and the permanent magnets d and dl during rotation is reduced. I'm taking it. Therefore, the above-mentioned bridge parts i and i1 must secure a required minimum predetermined width dimension. On the other hand, as shown in an enlarged view of a part of the rotor in FIG. 7 in FIG. 8, a magnetic flux for short-circuiting between the adjacent magnetic pole core h1 passes through the bridge portion i1. In order to prevent such a magnetic flux short circuit, it is desirable that the width of the bridge portion i1 be narrow.

Therefore, the width dimension of the bridge portion i1 is set to a minimum enough to withstand centrifugal force during rotation. Nevertheless, there is still a certain amount of leakage magnetic flux, and the effective magnetic flux has decreased, and the motor characteristics have deteriorated.

Also, during operation of the motor, an electromagnetic force other than the centrifugal force acts on the magnetic pole core h1. In addition to the normal direction, this electromagnetic force also has a tangential component that is a driving torque and a moment that attempts to rotate the magnetic pole core. And the amount changes.

For this reason, the force acting on the bridge portion i 1 is not uniform on both sides of the magnetic pole core h 1, and is a repetitive load, which easily causes breakage. The width dimension of the bridge portion i1 needs to be larger than when only the centrifugal force is considered, while the effective magnetic flux is further reduced.

The situation described above is exactly the same for the rotor having the anti-arc permanent magnet d shown in FIG. In particular, when the flux barriers g are provided at both ends of the punched hole c1 shown in FIGS. 7 and 8, the circumference of the bridge portion i1 becomes longer. Since the strength is reduced, it is necessary to further increase the width dimension.

In each case, when a rare earth magnet is used for the permanent magnets d and dl, a large torque is generated compared to the size of the rotor. Occurs, and a large force is easily generated in the bridge portions i and i1, and the width dimension of the bridge portion must be increased.

The present invention relates to a rotor in which a permanent magnet is fitted into a punched hole provided in a rotor core, with an increase in a width dimension of a bridge portion between an edge of the punched hole and a peripheral surface of the rotor core. An object of the present invention is to provide a motor rotor that suppresses such an increase in leakage magnetic flux and causes less deterioration in motor characteristics.

Disclosure of the invention

In the rotor of the electric motor of the present invention, a rotor core in which a plurality of thin steel plates are laminated and integrated, and a rotor core penetrated by the rotor core and provided adjacent to each other along the outer periphery of the rotor core. A plurality of perforated holes, and a permanent magnet fitted into the perforated holes and fixed to a rotor core, wherein the perforated hole edge and the rotor iron are formed at adjacent ends of the perforated holes. The width between the outer circumferential surface and the circumferential surface is set to be larger (W1 <W2) than the width W1 at the end in the anti-rotation direction and the width W2 at the end in the rotation direction. As the permanent magnet, a rare earth magnet such as neodymium, iron or boron may be used.

According to the present invention, the bridge portions on both sides of the magnetic pole core are set such that the width in the rotation direction on which a larger force acts is set to be larger than the width in the opposite rotation direction. An increase in leakage flux due to an increase in the width of the bridge can be suppressed, and the motor characteristics are less likely to deteriorate.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows an embodiment of the present invention. View.

FIG. 2 is a cross-sectional view of the rotor, showing the first embodiment of the present invention.

FIG. 3 is a cross-sectional view of a rotor according to a second embodiment of the present invention. FIG. 4 is a partially enlarged view of the rotor of the embodiment.

FIG. 5 is a view for explaining the electromagnetic force acting on the magnetic pole core of the embodiment.

Figure 6 is a cross-sectional view of a conventional rotor.

FIG. 7 is a cross-sectional view of a further different conventional rotor.

Figure 8 is a partially enlarged view of the conventional model. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Figure 1 shows the completed motor rotor.

In the rotor, a large number of thin steel plates 1 are stacked, and end plates 2 are stacked on upper and lower end surfaces thereof, and are fixed to the thin steel plates 1 by rivets 3. A shaft hole 4 for fitting the rotation shaft is provided in the center portion so as to penetrate the upper and lower end surfaces.

FIG. 2 is a cross-sectional view of the rotor, in which a rotor core 5 formed by laminating thin steel plates 1 is integrated with each other along the outer periphery of the rotor core and penetrated by the rotor core. It is composed of a plurality (four) of punching holes 6 provided adjacent to each other, and a permanent magnet 7 fitted into each of the punching holes and fixed integrally to the rotor core.

The rotor core 5 is provided with a shaft hole 4 at the center thereof. Referred to as a center core 8 between the inner shaft hole peripheral portion and the permanent magnet 7 circumference of, and _c referred to between the KakuHisashi permanent magnet 7 outer periphery and the rotor core 5 circumferential surface magnetic pole core 9, punching holes 6 end The bridge between the edge of the rotor core and the peripheral surface of the rotor core 5 is called a bridge portion 10. The bridge 10 connects the center core 8 and the magnetic pole core 9.

The permanent magnet 7 is formed in an anti-arc shape together with the punched hole 6, and due to a manufacturing problem, a slight gap is formed between both end edges of the punched hole 6 and both end edges of the permanent magnet 7. Gap exists.

Then, assuming that the rotor rotates in the counterclockwise direction, which is the direction of the arrow, the rotation direction side of the prism portions 10a and 10b on both sides of the magnetic pole core 9 is assumed. The width W'2 of the bridge 10a is larger than the width W1 of the bridge 10b in the anti-rotation direction.

(W 1 <W 2) are formed.

FIG. 3 shows a rotor according to another embodiment.

In this case as well, the basic configuration in which a plurality of straight punched holes 61 are provided in the rotor core 51 formed by laminating thin steel plates and the straight permanent magnets 71 are fitted therein remains unchanged. The center core 81 between the circumference of the shaft hole 41 and the inner circumference of the permanent magnet and the pole core 91 between the outer circumference of each permanent magnet and the circumference of the rotor core are also the same. Holes called flux barriers 20 are continuously provided at both ends of each punched hole 61 to prevent short-circuit of magnetic flux. A portion between the edge of the flux snare 20 and the peripheral surface of the rotor core 91 is called a bridge portion 100.

As shown in the enlarged view of FIG. 4, the magnetic pole core 9 1 is assumed to be rotated in the counterclockwise direction, which is the direction of the arrow. Of the bridge portions 100 on both sides, the width dimension W2 of the bridge portion 100a on the rotation direction is the width dimension W of the bridge portion 100b on the opposite rotation direction. It is formed larger than 1 (W 1 and W 2). Next, an operational description will be given based on the configuration of the rotor having the straight permanent magnets 71 described with reference to FIGS. 3 and 4, but basically, the anti-circle described with reference to FIG. The same is true for a rotor using an arc-shaped permanent magnet 7.

As schematically shown in FIG. 5, assuming that the rotor rotates counterclockwise as a rotor, an electromagnetic force is applied to the magnetic pole core 91 in addition to the centrifugal force. In particular, stress is concentrated on the bridge portion 100, but the bridge portion 100a on the rotation direction side is higher than the bridge portion 100b on the opposite rotation direction side. And more force is applied.

On the other hand, the short-circuited magnetic flux between the magnetic pole cores 91 passing through the bridge portion 100 also passes through the narrower bridge portion 100b on the non-rotational direction side. Even if the width of the bridge portion 100a on the side is large, the short-circuit magnetic flux does not increase so much.

Therefore, it is possible to construct a rotor of an electric motor in which the width of the rotating portion 100a is larger than the width of the rotating portion 100b. As a result, the reliability of the bridge portions 100a and 100b during operation can be increased without significantly reducing the motor characteristics.

Then, the rotor provided with the flux snare 20 at the end of the punched hole 61 into which the permanent magnet 71 of the rotor core 51 is fitted is used as the flux barrier. Comparatively provided on the periphery Because of the large holes, the strength around the black spear is low.

However, at the adjacent ends of the punched holes 6 1, the width between the edge of the punched hole and the peripheral surface of the rotor core 51 is defined as the width of the end in the anti-rotational direction, W By setting the width dimension W 2 of the end in the rotation direction to be larger (W 1 <W 2) than in 1, the strength is assured and the reliability is improved.

The same effect can be obtained in the rotor having the anti-arc-shaped punched hole 6 and the permanent magnet 7 having the same shape as shown in FIG. 2 by setting the same setting conditions. can get.

Furthermore, rotors using rare earth magnets such as neodymium, iron, boron, etc. for the permanent magnets 7, 71 have a large torque for their size, but the same setting conditions are used. Therefore, it is possible to prevent breakage of the bridge portions 100 and 100, thereby improving reliability, suppressing an increase in leakage magnetic flux due to an increase in the width of the bridge portion, and lessening deterioration of motor characteristics. You can get the rotor.

As described above, according to the present invention, the width of the ridge on both sides of the magnetic pole core is set to be larger in the rotational direction where a larger force is applied than in the opposite direction. In addition, an increase in the leakage flux due to an increase in the width of the bridge portion is suppressed, and the effect of reducing the deterioration of the motor characteristics is achieved.

Industrial applicability

As described above, the present invention is effective in the technical field of the rotor of an electric motor in suppressing the increase in the leakage magnetic flux due to the increase in the width of the bridge portion and preventing the deterioration of the electric motor characteristics. It is.

Claims

The scope of the claims

1. A rotor core formed by laminating and integrating a plurality of thin steel plates, and a plurality of punched holes penetrated by the rotor core and provided adjacent to each other along the outer periphery of the rotor core. And a permanent magnet fitted into the punched hole and fixed to the rotor core.

At the adjacent ends of the above-mentioned punched holes, the width dimension between the punched hole edge and the rotor core peripheral surface is set to the rotational direction end with respect to the width dimension W1 of the anti-rotational side end A motor rotor characterized in that the width W2 of the motor is set large (W1 <W2).

2. The motor rotor according to claim 1, wherein the permanent magnet is made of a rare earth magnet such as neodymium, iron, boron or the like.