JPH04156243A - Permanent magnet rotor - Google Patents

Abstract

PURPOSE:To make bridges at both the ends of a slot not easily bendable by providing a cantilevered bridge connecting the tip portion to the base portion of a magnetic pole and also alternately laminating the side having a bridge and the side having no bridge. CONSTITUTION:A rotor comprises a yoke 2 formed by laminating a plurality of silicon steel plates fixed by caulking and a rare earth element-iron-boron- based permanent magnet 3. Slots 2a are provided at every magnetic pole in the yoke 2 at an equal distance from the center of rotation and are fixed by caulking at the portion of two magnetic poles having no slot 2a. The slot 2a is half-closed. That is, a bridge 2b connecting the tip of magnetic pole to the base portion of magnetic pole is cantilevered. Its shape is point-symmetrical with respect to the center of rotation and has a bridge 2b at one side and no bridge at the other side. The slots are alternately laminated. By doing this, the width of bridge 2b can be made wider, so that the mechanical strength is increased, and bending in punching direction can be reduced when blanking the silicon steel plate.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a permanent magnet rotor for a brushless motor.

[Prior Art] An exploded perspective view of a conventional permanent magnet rotor is shown in FIG. 3. As shown in FIG. 3, a rotor 11 is composed of a yoke 12 and a permanent magnet 13. FIG. 4 shows a plan view of the silicon copper plate constituting the yoke 12. The yoke 12 has a plurality of slots 12a for each magnetic pole into which the permanent magnets 13 are inserted, and the slots 12a are of a closed type so that the permanent magnets are not inserted into the yoke 12. 13 was inserted in the axial direction.

In addition, the width of the bridges 12b, which are located at both ends of the slot 12a and connect the tip of the magnetic pole and the base of the magnetic pole, is determined by the width of the bridge 12b, which is designed to reduce the leakage flux generated from both ends of the permanent magnet 13 as much as possible. It was made as narrow as possible without causing any problems when stacking.

[Problems to be Solved by the Invention] However, there is a problem with the structure of a conventional permanent magnet rotor in which a closed slot 12a is provided in the yoke 12 of the rotor 11 and the width of the bridges 12b at both ends is made as narrow as possible. However, there is a limit to how narrow the width of the bridge 12b can be due to the mechanical strength against centrifugal force, and especially when punching a silicon steel plate, the bridge 12b tends to bend in the punching direction, making lamination difficult and resulting in a low yield. I had an issue. Furthermore, the permanent magnet 13 is inserted into the slot 12.
Since it is inserted in the axial direction into a, it is not only difficult to insert it if misalignment occurs, but also the problem is that the clinching mechanism is weakened due to excessive force acting on the silicon steel plate, and the surface of the permanent magnet 13 is also easily scratched. was.

An object of the present invention is to eliminate the drawbacks of the prior art and provide a permanent magnet rotor in which the bridges at both ends of the slots are difficult to bend and permanent magnets can be easily inserted.

[Means for Solving the Problems] A permanent magnet rotor according to the present invention has a yoke formed of a plurality of laminated silicon steel plates, the yoke having at least four magnetic poles on its outer periphery, and the magnetic poles having at least four magnetic poles. In a rotor of a brushless motor, slots into which permanent magnets are inserted are provided at equal distances from the center of rotation at every other magnetic pole, and the slots have surfaces facing the rotating shaft having the same magnetism. The slot of the steel plate is semi-closed, that is, the bridge connecting the tip of the magnetic pole and the base of the magnetic pole is cantilevered, and the side with the bridge and the side without the bridge are stacked alternately.

[Examples] Examples of the present invention will be described below based on the drawings. 1st
The figure is an exploded perspective view of a permanent magnet rotor in an embodiment of the present invention. The permanent magnet rotor 1 includes a yoke 2 formed by laminating a plurality of #I silicon plates and fixing them by caulking, and a rare earth-iron-boron magnet 3 which is a permanent magnet. York 2
Two slots 2a are provided at the same distance from the center of rotation at every other magnetic pole, and the two slots 2a are fixed by caulking using the two magnetic sections without the slots 2a.

FIG. 2 shows a plan view of the silicon copper plate forming the yoke 2.
As shown in FIG. 2, the slot 2a is semi-closed, that is, the bridge 2b connecting the tip of the magnetic pole and the base of the magnetic pole is cantilevered, and the shape is symmetrical with respect to the center of rotation. There is a side without. # in Figure 2
Well, the bridge 2 is on the left side of the slot 2a when viewed from the center of rotation.
b exists, but if you turn it over, the bridge 2b will become the slot 2a when viewed from the opposite side of FIG. 2, that is, from the center of rotation.
comes to the right of The silicon steel plates punched out in this manner are stacked one on top of the other in alternating fashion.

Thereafter, the permanent magnet 3 is inserted into the slot 2a in the axial direction.

Therefore, since the width of the bridge 2b can be increased, the mechanical strength increases, and the silicon copper plate becomes difficult to bend in the punching direction during punching. Since it is easy to stack them together, the yield is improved, and misalignment is less likely to occur, when inserting the magnet, no excessive force is applied to the silicon steel plate, and the magnet surface is also less likely to be damaged. In addition, since the slot 2a is cantilevered, there is no leakage of magnetic flux on the side without the bridge, and even if the width of the bridge 2b is made wider than that of the conventional closed type, the leakage of magnetic flux does not increase overall. Even if the two silicon copper plates are semi-closed, the permanent magnet 3 will not come out from the slot 2a by alternately stacking the front and back plates.

Although a rare earth-iron-boron magnet was used as the permanent magnet in this example, the permanent magnet material is not limited to a rare-earth-iron-boron magnet;
It goes without saying that the same process can be performed using various magnets such as samarium/cobalt (samarium/cobalt) magnets.

[Effects of the Invention] As described above, according to the present invention, the width of the bridge can be increased, so the mechanical strength is increased, and when punching a silicon steel plate, it becomes difficult to bend in the punching direction. It is easy to stack them together and the yield is improved.

Furthermore, since misalignment is less likely to occur, excessive force is not applied to the silicon copper plate when inserting the magnet, and the magnet surface is also less likely to be damaged.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view of a permanent magnet rotor in an embodiment of the present invention. FIG. 2 is a plan view of the silicon steel plate shown in FIG. 1. FIG. 3 is an exploded perspective view of a conventional permanent magnet rotor. FIG. 4 is a plan view of the silicon steel plate shown in FIG. 3. 1.11.--Permanent magnet rotor2.
12...Yoke 2a, 12a...
...Slot 2b, 12b...Bridge

Claims (1)

[Claims] A yoke is formed by a plurality of laminated silicon steel plates, the yoke has at least four magnetic poles on its outer periphery, and slots for inserting permanent magnets are provided in the magnetic poles at equal distances from the center of rotation at every other magnetic pole. In the brushless motor rotor, the slots have the same magnetism on the side facing the rotating shaft, and the slots of the silicon steel plate are semi-closed, that is, the tips of the magnetic poles and the bases of the magnetic poles are the same. A permanent magnet rotor characterized in that the bridge connecting the two is cantilevered, and the side with the bridge and the side without the bridge are alternately laminated.