JP2008131692A - Rotor of permanent magnet motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotor of a permanent magnet motor, capable of ensuring a distance between different polarity magnets adjacent in an axial direction without requiring chamfering processing for magnets. <P>SOLUTION: The rotor is used for the permanent magnet motor having a plurality of permanent magnets (20, 30) which are disposed in an axial direction and sequentially skewed in a circumferential direction. The rotor has intermediate magnet portions (40, 50) between the permanent magnets (20, 30) of adjacent upper and lower stages. The intermediate magnet portions (40, 50) are configured so that the edge line of the skew direction side are positioned on the extension of the edge lines of the skew direction side of the upper stage permanent magnets (20, 30), and the edge lines different from the skew direction side are positioned on the extension of the edge lines different from the skew direction side of the lower stage permanent magnets (20, 30). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a rotor of a permanent magnet motor having a plurality of permanent magnets arranged in the axial direction and sequentially skewed in the circumferential direction, and more particularly to a technique for reducing leakage of magnetic flux in the axial direction caused by the skew. is there.

As is well known, a permanent magnet motor in which a permanent magnet is provided on a rotor generates a kind of torque pulsation called cogging torque. Since this cogging torque causes problems such as deterioration of controllability of the motor and generation of noise, it is desirable to suppress it as much as possible.
FIG. 12 is a side view illustrating a rotor of a conventional permanent magnet motor having a configuration for reducing cogging torque. FIGS. 13 and 14 are a plan view and a perspective view of the rotor, respectively.
This rotor includes a rotor core (made of a laminated core) 100 and a predetermined number of N-pole permanent magnets 200 and S-pole permanent magnets 300 attached to the peripheral surface of the rotor core 100. In this rotor, the number of arrangement stages of the N-pole permanent magnet 200 and the S-pole permanent magnet 300 with respect to the axial direction is set to 2, but an arrangement number greater than 2 is adopted as necessary.

Adjacent upper and lower N pole permanent magnets 200 and adjacent upper and lower S pole permanent magnets 300 are shifted in the circumferential direction of the rotor core 100. This is generally called step skew. This step skew is effective for reducing the cogging torque. (For example, see Patent Document 1)
However, there are cases where the cogging torque cannot be sufficiently reduced even if the step skew is applied. The reason is as follows.

That is, in order not to reduce the effect of suppressing the cogging torque due to the stage skew, the magnetoresistance between the different polarity magnets adjacent in the axial direction of the rotor (in FIG. 12, the upper N pole permanent magnet 200 and the lower right S The magnetic resistance between the pole permanent magnet 300 and the magnetic resistance between the upper left S pole permanent magnet 300 and the lower N pole permanent magnet 200) is increased, and the amount of magnetic flux leakage in the axial direction is increased. Need to be reduced. (For example, refer to Chapter 5 of Non-Patent Document 1)
However, depending on the degree of skew amount in the step skew, the relative distance between the magnets having different polarities adjacent to each other in the axial direction becomes extremely small, that is, the magnetic resistance between the magnets decreases, and the step skew causes The cogging torque reduction effect may not be fully exhibited.

In view of this, as exemplified by the chain line in FIG. 12, a method has been proposed in which the opposite corners of the different polarity magnets are cut obliquely. (For example, see Patent Document 2)
According to this method, a space is formed between the magnets of different polarity and the magnetic resistance between the magnets is increased, so that leakage of magnetic flux in the axial direction is reduced.

Japanese Utility Model Publication No. 61-17876 "Materials of the Institute of Electrical Engineers of Japan" Stationary Machine, Rotating Machine Joint Study Group, SA-05-21, RM-05-20, "Cogging Torque Analysis of Skewed Surface Magnet Motor Considering Lamination of Electrical Steel Sheets", Tetsuya Hattori, Issei Narita, January 28, 2005, published by the Institute of Electrical Engineers of Japan JP 2003-339129 A

By the way, when adopting the method of obliquely cutting the corners of the magnet as described above, unless the cutting angles of all the magnets are uniform, the shape of each space formed by the oblique cutting becomes uneven, that is, The magnetic resistance provided by each space becomes uneven, and there is a risk of generating a cogging torque with an unexpected period.
However, it is not easy to accurately and obliquely cut the corners of the magnet having a curved shape in an arc shape. Therefore, when the above method is adopted, the product quality due to the unevenness of the magnetoresistance is not obtained. Variations can occur. If a cutting device with high processing accuracy is used, the corners of the magnet can be accurately and obliquely cut. However, since such a cutting device is expensive, the equipment cost is increased.
Therefore, an object of the present invention is to provide a rotor for a permanent magnet motor capable of ensuring a large distance between different polarity magnets adjacent to each other in the axial direction without requiring a process of obliquely cutting the corners of the magnet. Is to provide.

  The present invention is a rotor of a permanent magnet motor having a plurality of permanent magnets arranged in the axial direction and sequentially skewed in the circumferential direction, and in order to achieve the above object, between the adjacent upper and lower permanent magnets The intermediate magnet portions are respectively formed on the two. In the intermediate magnet portion, the edge line on the skew direction side is positioned on the extension of the edge line on the skew direction side of the upper permanent magnet, and the edge line on the side opposite to the skew direction side is on the lower stage. It is comprised so that it may be located on the extension of the edge line on the opposite side to the said skew direction side of a permanent magnet.

  The intermediate magnet portion includes, for example, a first extension protruding from the upper permanent magnet toward the lower permanent magnet, and a second extension protruding from the lower permanent magnet toward the upper permanent magnet. It consists of an extension. The first and second extensions are formed so as to be combined without a gap.

The first and second extensions are formed so that their boundary lines are stepped or oblique, or are present in a plane perpendicular to the axis, or are V-shaped. Can do.
The intermediate magnet portion may be formed by the upper permanent magnet or an extension of the lower permanent magnet, or may be formed by a permanent magnet independent of the upper and lower permanent magnets. .

  According to the present invention, in forming the space between the different polarity magnets adjacent to each other in the axial direction, it is not necessary to cut the corners of the magnets obliquely. This is advantageous in making the magnetic resistance uniform between the different polarity magnets adjacent in the axial direction. Moreover, since the magnet for forming the space can be easily processed, the product cost can be reduced.

FIG. 1 is a side view showing a rotor of a permanent magnet motor according to a first embodiment of the present invention. FIG. 2 is a plan view of the rotor.
The rotor R-1 includes a rotor core (consisting of a laminated core) 10 and a predetermined number of N-pole permanent magnets 20 and S-pole permanent magnets 30 attached to the peripheral surface of the rotor core 10. .
In this rotor R-1, the number of arrangement stages of the N-pole permanent magnet 20 and the S-pole permanent magnet 30 in the axial direction (vertical direction in FIG. 1) is set to 2, but a larger number of arrangement stages is set. May be. Further, in this rotor R-1, a total of four N-pole permanent magnets 20 and S-pole permanent magnets 30 are arranged in the circumferential direction, but this arrangement number is also a desired number 2 × n (n = 1). , 2, 3...

The lower N-pole permanent magnet 20 is shifted in the circumferential direction of the rotor core 1 with respect to the upper N-pole permanent magnet 20. Similarly, the lower S-pole permanent magnet 30 is changed to the upper S-pole permanent magnet 30. On the other hand, it is shifted in the circumferential direction of the rotor core 1 (generally called step skew, and the direction of the skew is indicated by an arrow A in FIG. 1).
An N-pole intermediate magnet portion 40 is formed between the adjacent upper N-pole permanent magnet 20 and the lower N-pole permanent magnet 20, and the upper S-pole permanent magnet 30 and the lower S-pole permanent magnet 30 adjacent to each other. An S pole intermediate magnet portion 50 is formed between them. Note that the north pole intermediate magnet portion 40 and the south pole intermediate magnet portion 50 are respectively hatched.

  The N-pole intermediate magnet portion 40 is located on the extension of the skew line A side edge line (along the axis of the rotor) 21 of the upper N pole permanent magnet 20 with the edge line 43 on the skew direction A side, The edge line 44 opposite to the skew direction A side has a shape located on the extension of the edge line 22 opposite to the skew direction A side of the lower N-pole permanent magnet 20. The south pole intermediate magnet portion 50 also has a shape according to the north pole intermediate magnet portion 40.

In this embodiment, the N-pole intermediate magnet unit 40 includes an extension 41 projecting from the upper N-pole permanent magnet 20 toward the lower N-pole permanent magnet 20, and the upper N-pole permanent magnet 20 from the upper N-pole permanent magnet 20. It is configured by combining an extension 42 that protrudes toward the permanent magnet 20.
Similarly, the S pole intermediate magnet portion 50 includes an extension 51 projecting from the upper S pole permanent magnet 30 toward the lower S pole permanent magnet 30, and an upper S pole permanent magnet from the lower S pole permanent magnet 30. It is configured by combining an extension portion 52 protruding toward 30.
The extension part 41 and the extension part 42 are formed so that no gap is formed between them, and the boundary lines thereof are stepped, and the extension part 51 and the extension part 52 are also formed in the same manner.

According to the rotor R-1 according to this embodiment configured as described above, the upper N-pole permanent magnet 20 and the lower S adjacent to the magnet 20 in the axial direction of the rotor R-1. A space 60 is formed between the pole permanent magnet 30 (in FIG. 1, the lower right S pole permanent magnet 30), and thereby the magnetic resistance between the magnets 20 and 30 is increased.
A space 60 is also formed between the upper S pole magnet 30 (in FIG. 1, the upper left S pole permanent magnet 30) and the lower N pole permanent magnet 20 adjacent to the magnet 30 in the axial direction. As a result, the magnetic resistance between the magnets 30 and 20 is increased.

As described above, the magnetic resistance affects the cogging torque of the motor. That is, when the magnetic resistance is low, the amount of magnetic flux leakage in the axial direction of the rotor increases, so that the effect of suppressing the cogging torque due to step skew is reduced.
However, as described above, according to the rotor R-1 according to the present embodiment, the magnetic resistance between the N-pole permanent magnet 20 and the S-pole permanent magnet 30 adjacent in the axial direction is increased by the space 60. Therefore, the effect of reducing the cogging torque due to the step skew is sufficiently exhibited.
Moreover, according to the rotor R-1 according to the present embodiment, the N pole intermediate magnet portion 40 is configured by combining the extension portions 41 and 42, and the S pole is set by combining the extension portions 51 and 52. Since the intermediate magnet unit 50 is configured, positioning of the lower N-pole permanent magnet 20 with respect to the upper N-pole permanent magnet 20 and positioning of the lower S-pole permanent magnet 30 with respect to the upper S-pole permanent magnet 30 are facilitated. Become.
As shown in FIG. 3, the extension portions 41 and 42 constituting the N-pole intermediate magnet portion 40 and the extension portions 51 and 52 constituting the S-pole intermediate magnet portion 50 are arranged with respect to the circumferential direction of the rotor core 1. You may form so that it may be located on the opposite side to FIG.

FIG. 4 shows a rotor of a permanent magnet motor according to the second embodiment of the present invention. This rotor R-2 relates to the first embodiment in the shapes of the extension portions 41 and 42 constituting the N-pole intermediate magnet portion 40 and the shapes of the extension portions 51 and 52 constituting the S-pole intermediate magnet portion 50. It is different from the rotor R-1.
That is, the extension portions 41 and 42 (51 and 52) in the rotor R-2 are formed so that the boundary lines of each of the rotor R-2 indicate a diagonal line rising to the right. Of course, the extension portions 41 and 42 (51 and 52) may be formed so that the boundary line shows a slanting line with a downward slope as shown in FIG.

FIG. 6 shows a rotor of a permanent magnet motor according to the third embodiment of the present invention. This rotor R-3 also relates to the first embodiment in the shape of the extension portions 41 and 42 constituting the N-pole intermediate magnet portion 40 and the shape of the extension portions 51 and 52 constituting the S-pole intermediate magnet portion 50. It is different from the rotor R-1.
That is, the extension portions 41 and 42 (51 and 52) in the rotor R-3 are formed so that their boundary lines exist in a plane perpendicular to the axis of the rotor R-3.

FIG. 7 shows a rotor of a permanent magnet motor according to the fourth embodiment of the present invention. In the rotor R-4, the N pole intermediate magnet portion 40 is configured by the extension portions 41 and 42 formed such that the boundary lines thereof are V-shaped. Similarly, the boundary lines of the rotor R-4 are V-shaped. The S-pole intermediate magnet portion 50 is configured by the extension portions 51 and 52 formed so as to show.
The extension portions 41 and 42 (51 and 52) may be formed so that their boundary lines have an inverted V shape as shown in FIG.

FIG. 9 shows a rotor of a permanent magnet motor according to the fifth embodiment of the present invention. In this rotor R-5, the N pole intermediate magnet portion 40 is constituted by an extension portion 45 of the lower N pole permanent magnet 20, and the S pole intermediate magnet portion 50 is an extension portion 55 of the lower S pole permanent magnet 30. It consists of
As shown in FIG. 10, the N pole intermediate magnet portion 40 is constituted by the extension portion 46 of the upper N pole permanent magnet 20, and the S pole intermediate magnet portion 50 is constituted by the extension portion 56 of the upper S pole permanent magnet 30. It may be configured.
Of course, the N pole intermediate magnet portion 40 is constituted by an extension 45 of the lower N pole permanent magnet 20 as shown in FIG. 9, while the S pole intermediate magnet portion 50 is formed as an upper S pole permanent magnet as shown in FIG. 10 and the N pole intermediate magnet portion 40 is constituted by the extension portion 46 of the upper N pole permanent magnet 20 as shown in FIG. 10, while the S pole intermediate magnet portion 50 is shown in FIG. As shown in FIG. 5, a configuration in which the lower portion of the S pole permanent magnet 30 is configured by the extension 55 can be employed.
In short, the N-pole intermediate magnet portion 40 may be formed by any extension of the upper and lower N-pole permanent magnets 20. Similarly, the S-pole intermediate magnet portion 50 is formed by the upper and lower S-pole permanent magnets 30. Any extension may be used.

  FIG. 11 shows a rotor of a permanent magnet motor according to the sixth embodiment of the present invention. In this rotor R-6, the N-pole intermediate magnet portion 40 and the S-pole intermediate magnet portion 50 are constituted by a single N-pole permanent magnet 47 and an S-pole permanent magnet 57, respectively. Instead of the single N-pole permanent magnet 47 and the S-pole permanent magnet 57, a pole permanent magnet obtained by dividing them into a plurality of pieces (the division direction may be either the axial direction or the circumferential direction of the rotor). It is also possible to use it.

Since each of the rotors R-2 to R-6 according to the second to sixth embodiments described above is formed with the space 60, similarly to the rotor R-1 according to the first embodiment, The magnetic resistance between the different polarity magnets 20 and 30 adjacent in the axial direction can be increased, that is, the leakage of magnetic flux in the axial direction can be reduced.
Further, according to the rotors R-1 to R-6 according to the first to sixth embodiments described above, when the space 60 is formed between the different polarity magnets 20 and 30 adjacent in the axial direction, those magnets are used. Since the process which cut | disconnects the corner | angular part of 20 and 30 diagonally is not required, it is advantageous when aiming at equalization of the shape of the said space, ie, the uniform magnetic resistance between the magnets 20 and 30. FIG. In addition, since the magnets 20 and 30 for forming the space 60 can be easily processed, the product cost can be reduced.

It is a side view which shows the rotor which concerns on the 1st Embodiment of this invention. It is a top view of the rotor shown in FIG. It is a side view which shows the modification of the intermediate magnet part in the rotor shown in FIG. It is a side view which shows the rotor which concerns on the 2nd Embodiment of this invention. It is a side view which shows the modification of the intermediate magnet part in the rotor shown in FIG. It is a side view which shows the rotor which concerns on the 3rd Embodiment of this invention. It is a side view which shows the rotor which concerns on the 4th Embodiment of this invention. It is a side view which shows the modification of the intermediate magnet part in the rotor shown in FIG. It is a side view which shows the rotor which concerns on the 5th Embodiment of this invention. It is a side view which shows the modification of the intermediate magnet part in the rotor shown in FIG. It is a side view which shows the rotor which concerns on the 6th Embodiment of this invention. It is a side view which shows the structural example of the conventional rotor. It is a top view of the rotor shown in FIG. It is a perspective view of the rotor shown in FIG.

Explanation of symbols

R-1 to R-6 Rotor 10 Rotor core 20 N-pole permanent magnet 21, 22 Edge line 30 S-pole permanent magnet 40 N-pole intermediate magnet part 41, 42 Extension part 43, 44 Extension 47 N-pole permanent magnet 50 S pole intermediate magnet part 51, 52 Extension part 57 S pole permanent magnet 60 Space

Claims (8)

A rotor of a permanent magnet motor having a plurality of permanent magnets arranged in the axial direction and sequentially skewed in the circumferential direction,
An intermediate magnet portion is formed between the adjacent upper and lower permanent magnets,
In the intermediate magnet portion, the edge line on the skew direction side is positioned on the extension of the edge line on the skew direction side of the upper permanent magnet, and the edge line on the side opposite to the skew direction side is A rotor of a permanent magnet motor, characterized in that the rotor is located on an extension of an edge line on the side opposite to the skew direction side of the lower permanent magnet.   The intermediate magnet portion includes a first extension projecting from the upper permanent magnet toward the lower permanent magnet, and a second extension projecting from the lower permanent magnet toward the upper permanent magnet. The rotor of a permanent magnet motor according to claim 1, wherein the first and second extensions are formed so as to be combined without a gap.   The rotor of a permanent magnet motor according to claim 2, wherein the first and second extensions are formed such that their boundary lines are stepped.   The rotor of a permanent magnet motor according to claim 2, wherein the first and second extension portions are formed such that their boundary lines indicate diagonal lines.   3. The rotor of a permanent magnet motor according to claim 2, wherein the first and second extensions are formed such that their boundary lines exist in a plane perpendicular to the axis. 4.   The rotor of a permanent magnet motor according to claim 2, wherein the first and second extensions are formed such that their boundary lines are V-shaped.   The rotor of a permanent magnet motor according to claim 1, wherein the intermediate magnet portion is formed by an extension portion of the upper permanent magnet or the lower permanent magnet.   2. The rotor of a permanent magnet motor according to claim 1, wherein the intermediate magnet portion is formed by a permanent magnet independent from the upper and lower permanent magnets.

Images