JP2747436B2 - Rotor with permanent magnet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotor with a permanent magnet in a motor utilizing not only magnet torque but also reluctance torque.

[0002]

2. Description of the Related Art Conventionally, a rotor in which one layer of permanent magnet is embedded in a rotor body made of a material having high magnetic permeability such as iron has been known. However, from the viewpoint of effective use of reluctance torque, the above conventional example is not preferable, and the present inventors have developed a two-layer rotor with permanent magnet as shown in FIG. (Japanese Patent Application No. 7-134023).

[0003] The rotor 3 according to this prior invention has a structure in which four sets of permanent magnets 8a, 8b,... Arranged at intervals in two layers in the radial direction of the rotor are embedded in an iron rotor body 3a. The permanent magnets 8a and 8b of each set are arranged adjacent to each other so that the S pole and the N pole are alternately arranged, and the permanent magnets 8a and 8b in a two-layer relationship are configured so that the polarities on the outer peripheral side are the same. Have been. Each of the outer permanent magnets 8a, ... and the inner permanent magnets 8b, ... is formed in an arc shape that is convex in the centripetal direction of the rotor, and the outer permanent magnet 8a and the inner permanent magnet 8a are in a two-layer relationship. Are arranged in parallel with the permanent magnet 8b, and the interval between them is constant.

[0004] As described above, the rotor 3 in which the permanent magnets 8a located on the outer peripheral side of the rotor and the permanent magnets 8b located on the inner peripheral side of the rotor are buried in two layers with a space therebetween is composed of a group of windings 10 on the stator 2 side. The rotating magnetic field generated by the
a, 8b) and the reluctance torque generated when a magnetic path due to the rotating magnetic field is formed on the surface side of the rotor body 3a or at the interval between the inner and outer permanent magnets 8b, 8a. It rotates with the combined torque of.

[0005]

In the configuration of the above-mentioned prior invention, the combined magnetic flux of the magnetic flux generated by the permanent magnet embedded in the rotor body and the magnetic flux generated by the winding on the stator side will be described below. The rotation direction R of the rotor 3
Tends to concentrate on the space between the ends of the permanent magnets located on the forward side of the motor.

FIGS. 5 to 7 show examples of magnetic field analysis. The magnetic field analysis shown in FIG. 5 is for the magnetic flux generated only by the permanent magnet 8. In the magnetic field analysis shown in FIG. 6, the position of the permanent magnet is regarded as the magnetic gap 8c, and the magnetic field analysis is performed on the magnetic flux generated by the winding 10 of the stator 2. Further, FIG.
The magnetic field analysis shown in FIG. 1 is for the combined magnetic flux of the permanent magnet 8 and the winding 10.

Here, an interval 3b between the ends of the permanent magnets located on the forward side of the rotor rotating in the direction indicated by R in FIG.
The lines of magnetic force are dense. Note that a blank portion indicated by 5 in FIG. 7 is a space sandwiched between the teeth 4.

[0008] The dense magnetic flux causes an increase in iron loss and the like, which causes heat generation of the rotor body 3a, and has a problem that the efficiency of the motor is reduced.

Further, in the configuration of the above-mentioned prior invention, since the permanent magnets are arranged in two layers at intervals so as to be substantially parallel to each other, two permanent magnets 8a and 8b with respect to the rotor surface are provided.
Is determined only by the surface area on the outer peripheral surface side of the permanent magnet 8a located substantially on the outer peripheral side of the rotor body 3a, and the magnet torque at both ends of the permanent magnet 8b located on the inner side cannot be effectively used. Had.

Therefore, a structure that can reduce the concentration of magnetic flux generated in the interval 3b between the ends of the permanent magnets located on the forward side in the rotation direction R and improve the efficiency of the motor has been desired.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to provide a rotor with a permanent magnet that can reduce the concentration of magnetic flux at a specific location and efficiently use a magnet torque and a reluctance torque.

[0012]

According to the present invention, in order to solve the above-mentioned problems of the prior art, two or more layers are arranged on a rotor body made of a material having high magnetic permeability in the radial direction of the rotor at intervals of two or more layers. In a rotor in which a plurality of sets of permanent magnets are buried, the interval between the layered permanent magnets is wider at least at the end portion located at the forward side in the rotation direction of the rotor than at other portions. It is characterized by having comprised so that it might become.

It is preferable that each of the permanent magnets disposed in two layers is formed in an arc shape that is convex in the centripetal direction of the rotor.

Further, the present invention solves the above-mentioned problems of the prior invention. In the above rotor, in the rotor, the center of curvature of the permanent magnet located on the inner peripheral side of the rotor is shifted from the center of curvature of the permanent magnet located on the outer peripheral side of the rotor. It is characterized in that it is provided so as to be located on the centrifugal side, and the interval between both ends of the permanent magnet in a layer relationship is formed wide.

[0015]

According to the present invention, the following operations can be performed by the above-mentioned structure. That is, the interval between the permanent magnets in the layer relationship is configured such that the interval at the end portion located at least on the forward side in the rotational direction of the rotor is wider than the interval at the other portions. The distance on the forward side of the rotor is widened, and the concentration of magnetic flux generated at the position on the forward side of the rotor rotating in the expanded direction can be reduced. Also, if each permanent magnet embedded in the two layers is formed in an arc shape that is convex in the centripetal direction of the rotor,
Since the magnetic flux related to the reluctance torque is smoothly guided between the permanent magnets along the convex arc, the magnetic resistance related to the formation of the magnetic path is reduced, and the motor efficiency can be improved.

Further, the center of curvature of the permanent magnet located on the inner peripheral side of the rotor is provided so as to be located on the rotor centrifugal side from the center of curvature of the permanent magnet located on the outer peripheral side of the rotor. If the gap between both ends is widened, both forward and reverse rotations of the motor will increase the gap on the forward side of the rotor, alleviating the concentration of magnetic flux in this part, An operation similar to the above can be performed. Also, the curvature center point of the permanent magnet having a multilayer structure is defined by claim 3.
In addition to the surface area of the permanent magnet located on the outer peripheral side, the surface area of both ends of the permanent magnet located on the inner peripheral side is added, and these are used magnetically effectively. Therefore, there is an effect of increasing the amount of magnetic flux on the rotor surface, and the magnet torque can be effectively used.

[0017]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a first embodiment of the present invention.

The rotor 3 is provided on the iron rotor body 3a at intervals of two layers per pole in the radial direction of the rotor.
The permanent magnets 8a, 8b,... Of each set are buried, and the permanent magnets 8a, 8b of each set are arranged adjacent to each other so that the S pole and the N pole are alternately arranged, and the permanent magnets 8a in a layer relationship are provided. , 8b
Are configured so that the polarity on the outer peripheral side is the same. Outer permanent magnets 8a,... And inner permanent magnets 8
are formed in an arc shape that is convex in the centripetal direction of the rotor.

Further, a distance 3b between the end portions of the permanent magnets 8 having the above-mentioned layer relation and located on the forward side in the rotation direction R of the rotor 3 is set.
Are formed wider than the intervals between the other portions. That is, when the rotor 3 rotates in the R direction shown in FIG. 1, the end portions 9a and 9b of the permanent magnets 8a and 8b on the forward side have a wide interval 3b as shown by W in the drawing, and the other end. The interval between the parts has a width smaller than the width W as indicated by x in the drawing.

On the other hand, a plurality of teeth 4 are provided on the stator 2 side.
The windings 10 are arranged between the teeth 4, and a current is applied to the group of the windings 10 to generate a rotating magnetic field.

In the above configuration, the rotor 3 is connected to the winding 1
The rotor main body 3a is covered with an iron material of a high magnetic permeability material that easily receives a rotating magnetic field generated by the group 0, and a permanent magnet 8 (8a, 8b) of a low magnetic permeability material through which a magnetic flux is difficult to pass. . Then, as shown in FIG.
The inductance is different between a d-axis direction, which is a radial direction passing through the center of the axis, and a q-axis direction, whose electrical angle is orthogonal to the direction.

In such a configuration, in the d-axis direction in FIG. 1, the magnetic flux generated by the group of windings 10 does not pass and the inductance can be made extremely small, while in the q-axis direction in which the d-axis and the electrical angle are orthogonal to each other. , Inner and outer permanent magnets 8b, 8
A magnetic path in the direction indicated by p in the drawing is formed at the interval a, and the magnetic flux easily passes through, the inductance increases, and the reluctance torque is effectively used. A magnetic path is also formed in the direction indicated by Pa in the drawing.

When the rotor 3 rotates in the direction indicated by R in FIG. 1, the magnetic flux in the prior art shown in FIG. 4 causes the magnetic flux in the prior art shown in FIG. In the width x), the magnetic flux is dense and easily saturated, but in the present embodiment, the distance between the end positions 9a and 9b of the permanent magnets 8a and 8b located on the forward side in the rotation direction R is set. Since the width 3b is provided wide as shown by W in FIG. 1, it is possible to reduce the concentration of the magnetic flux in the space 3b.

In the above embodiment, the rotation position and the rotation frequency of the rotor section 3 are detected in advance by a Hall element or an encoder, and the current flowing through the windings 10 of the stator 2 is a reluctance torque or a magnet torque. In order to obtain a large value, an alternating current having a frequency corresponding to the rotor speed is supplied by shifting the phase of the current so that the current value peaks at a position slightly shifted in phase from the q-axis.

Next, a second embodiment of the present invention will be described with reference to FIGS.

In the second embodiment, the curvature center point Rb of the permanent magnet 8b located on the inner peripheral side of the rotor among the arc-shaped permanent magnets 8 arranged in two layers of the first embodiment is located on the outer peripheral side of the rotor. Permanent magnets 8a and 8b which are provided so as to be located on the rotor centrifugal side from the curvature center point Ra of the permanent magnets 8a and have a layer relationship.
Is characterized in that the spaces 3b, 3b between both end portions 9a, 9b are formed wide. Since other configurations of the second embodiment are the same as those of the first embodiment, the same reference numerals are given to the common portions in FIG. 2 and the detailed description is omitted.

In the rotor 3 configured as described above, even if the rotor 3 rotates forward or backward, the interval 3b between the end positions 9a and 9b of the permanent magnets 8a and 8b located on the forward side in the rotation direction R becomes wide W, As in the first embodiment, it is possible to reduce the density of magnetic flux in the space 3b.

Further, as shown in FIG. 3 (a), the permanent magnet 8b located inside can generate more magnetic flux with respect to the rotor surface only by the portions 9c and 9d indicated by oblique lines in the figure.

That is, the magnetic flux N of the permanent magnet 8a located on the rotor surface side shown in FIG. 3B is backed up by the magnetic flux N at the central portion of the permanent magnet 8b having the same surface area as the permanent magnet 8a located on the back side. While the permanent magnet 8
The magnetic fluxes at both end portions 9c and 9d of "b" directly reach the surface of the rotor 3. Therefore, as shown in FIG. 3C, the magnetic flux generated by the permanent magnet 8a and the magnetic flux 9c, 9d
Is output. As described above, by increasing the effective surface area of the permanent magnet 8 and further increasing the amount of magnetic flux, a strong magnet torque can be obtained.

In the above embodiment, four permanent magnets 8
Although an example using a and 8b has been described, other numbers of sets may be used. Further, the shape of the permanent magnet 8 is not limited to an arc shape that is convex in the rotor centripetal direction. In the above embodiment, each of the permanent magnets 8a, 8b is constituted by a permanent magnet up to its end 9a, 9b. However, the end 9a, 9b is constituted by a void (air layer) or a synthetic resin layer. May be. That is, the present invention is not limited to the above embodiments, and various modifications are possible based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

[0032]

According to the present invention, in a rotor having a permanent magnet having a multi-layer structure, it is possible to reduce the concentration of magnetic flux at a specific location, reduce iron loss, and efficiently reduce magnet torque and reluctance torque. It is possible to provide a rotor with a permanent magnet that rotates with high efficiency by utilizing the same.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first embodiment of the present invention.

FIG. 2 is a partial sectional view showing a second embodiment of the present invention.

FIG. 3 shows the principle, and (a),
(B), (c) is a conceptual diagram.

FIG. 4 is a sectional view showing a prior art.

FIG. 5 is a diagram showing a magnetic field analysis result of a magnetic flux by a permanent magnet.

FIG. 6 is a diagram showing a magnetic field analysis result of a magnetic flux generated by a winding group.

FIG. 7 is a view showing a magnetic field analysis result of a synthetic magnetic flux generated by a permanent magnet and a winding group.

[Explanation of symbols]

 2 Stator 3 Rotor 3a Rotor main body 3b End side interval 4 Teeth 8, 8a, 8b Permanent magnet 9a, 9b End 10 winding

──────────────────────────────────────────────────の Continued on the front page (72) Inventor Hiroshi Ito 1006 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Nosunari Asano 1006 Kadoma, Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. Japanese Utility Model Application Hei 6-66277 (JP, U) US Patent 4,924,130 (US, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H02K 1/27 H02K 21/14-21/16

Claims (3)

(57) [Claims] 1. A rotor comprising a plurality of sets of permanent magnets arranged at intervals of two or more layers per pole in a rotor radial direction in a rotor body made of a high magnetic permeability material. A rotor with permanent magnets, wherein the distance between certain permanent magnets is configured such that the distance between the ends located at least on the forward side in the rotation direction of the rotor is wider than the distance between other parts. 2. The permanent magnets arranged in two layers are formed in an arc shape that is convex in the centripetal direction of the rotor.
A rotor with a permanent magnet as described in the above. 3. A rotor in which a plurality of sets of permanent magnets arranged at intervals of two or more layers per pole in a radial direction of the rotor are embedded in a rotor body made of a high magnetic permeability material. The center of curvature of the permanent magnet located on the side of the rotor is provided so as to be located on the rotor centrifugal side from the center of curvature of the permanent magnet located on the outer peripheral side of the rotor, and the gap between both ends of the permanent magnet in layer relation is widened. Rotor with permanent magnet.