JPH02184231A - Permanent magnet rotor - Google Patents

Abstract

PURPOSE:To obtain a rotor with low cost by arranging a plurality of arched magnets around a laminated core then shrinkage fitting a nonmagnetic metal pipe to the plurality of magnets and specifying the ratio between the outer diameter of the core and the inner diameter of the arched magnet. CONSTITUTION:Iron plates are laminated to form a core 1 and the outer diameter thereof is set DOY. Four arched permanent magnets 2 are arranged around the core 1 and the inner diameter thereof is set to D1M. Then a nonmagnetic pipe 3 is shrinkage fitted to the arched permanent magnet 2. The ratio between the outer diameter and the inner diameter is set in the range of DOY/D1M =0.999-0.993, and the corner section of the arched magnet 2 is bevelled as shown by an arrow R thus facilitating shrinkage fitting. By such arrangement, a motor having low magnetic circuit resistance and improved performance can be assembled easily without requiring die-cast.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a permanent magnet rotor having an iron core for forming a magnetic path near the inner diameter and permanent magnets on the outside thereof.

・Conventional technology A permanent magnet rotor without a starting winding generally has a structure in which the iron core is an inner core and permanent magnets are placed on the outside to increase the magnet area. In order to efficiently produce a rotor with this structure, a conventional method has been adopted (Japanese Patent Laid-Open No. 5
There is a publication No. 8-151855. This is done by placing a plurality of arch-shaped magnets inside a cylindrical cover, and placing a laminated iron plate with holes through which the molten metal passes during die-casting inside the magnets. The laminated iron plate is die-cast using a mold having an annular space communicating with the hole.

Problems to be Solved by the Invention However, the above conventional example had the following problems.

1. Cost issues a. Because die casting is required, manufacturing costs such as equipment costs are expensive.

b. Cutting is necessary because the dimensional accuracy of the inner diameter of the laminated core and the outer diameter of the cylindrical cover deteriorates due to the heat and pressure when the molten metal is heated during die casting.

C. Molten metal burrs are generated during die casting, so removal work is required.

2. Problems with motor performance a. Due to the gap between the magnet and the laminated core, the length of space in the entire magnetic path increases, resulting in a decrease in the amount of magnetic flux obtained and, as a result, deterioration of motor performance. .

50 In order to cut the outer diameter of the cylindrical cover, the inner diameter of the core and
An uneven thickness occurs in the cylindrical cover due to the misalignment of the concentricity of the cylindrical cover. In order to ensure the minimum wall thickness of the cylindrical cover, it is necessary to increase the average wall thickness, and if the cylindrical cover is conductive, eddy current loss will occur in this portion during motor operation.

There were problems such as.

In view of the above-mentioned problems, the present invention produces a permanent magnet rotor at a low cost with a structure in which a core for forming a magnetic path is provided near the inner diameter and permanent magnets are arranged around the outer circumference, thereby improving motor performance. The purpose is to

In the present invention, a plurality of arcuate magnets are arranged around the outer periphery of a laminated iron core or a block iron core, and a non-magnetic metal pipe is shrink-fitted and press-fitted onto the outer periphery of the plurality of magnets. At this time, the outer diameter of the core is within the range of the inner diameter of the arcuate magnet, and at least one corner formed by the end face and outer peripheral surface of the arcuate magnet is chamfered.

Effects According to the above configuration, a gap between the inner diameter of the bow-shaped magnet and the outer diameter of the iron core is formed on both sides of the bow-shaped magnet, so that after the metal pipe is shrink-fitted, the stress in the bow-shaped magnet is mainly in the tensile direction from both sides. As a result, it only breaks at the center of the bow, and no small chips occur, and only slight cracks occur. Therefore, protection of the magnet by die-casting molten metal is not necessary.

By applying a C-chamfer or double-chamfer to the corner formed by at least one end face and the outer diameter surface of the magnet, it becomes a guide when shrink-fitting a non-magnetic metal pipe, and also serves as a guide for non-magnetic metal pipes.
This is to prevent the inner diameter surface of the metal pipe from being scraped by the magnet during shrink-fitting press-fitting.

EXAMPLE Hereinafter, a permanent magnet rotor according to an example of the present invention will be explained with reference to the drawings.

Fig. 1 is a vertical cross-sectional view of a permanent magnet rotor according to an embodiment of the present invention, Fig. 2 is a cross-sectional view of Fig. 1, and Fig. 3 is an iron core outer diameter dimension and an arcuate magnet inner diameter dimension of Fig. 2. FIG. 4 is a partially enlarged view showing the relationship between the two, and FIG. 4 is a cross-sectional view of the non-magnetic metal pipe shown in FIG. 1 is a laminated iron core or a block iron core, 2 is an arcuate magnet having an arcuate cross section, 3 is a non-magnetic metal pipe, Dig is the inner diameter of the arcuate magnet 2, and Doy is the outer diameter of the core.

A plurality of arcuate magnets 2 (four in the figure) are arranged around the outer periphery of the iron core 1, and a nonmagnetic metal pipe 3 is shrink-fitted and press-fitted onto the outer periphery.

Here, an appropriate gap is formed between the inner diameter of the arcuate magnet 2 and the outer diameter of the iron core 1, and the arcuate magnet 2 is
This prevents the arcuate magnet 2 from being damaged.

At this time, the inner diameter (DIM) of the arcuate magnet 2 and the 0.
993, the center part of the arcuate core 2 is supported by the outer diameter of the core 1, with a slight gap on both sides as shown in FIG. The specific dimensions of the inner diameter (DIM) of the arcuate magnet 2 and the outer diameter (DOY) of the iron core 1 are as follows:
DOY=37.85m in this example.
m, DIM=38.0, the gap is 0.075m
n+ is closed.

With the above configuration, the stress applied to the arcuate magnet 2 after the non-magnetic metal pipe 3 is press-fitted is mainly tensile stress, so even if the arcuate magnet 2 is strong against cracking, it will not cause small chips. No cracking occurs, only slight cracking occurs. Therefore, protection of the magnet by die-casting molten metal is not necessary.

Furthermore, as shown in FIG. 4, by chamfering at least one corner formed by the end surface and the outer circumferential surface of the arcuate magnet 2, the arcuate magnet 2 can be made non-magnetic during shrink fitting of the non-magnetic metal pipe 3. It is possible to prevent the inner diameter surface of the metal pipe 3 from being scraped.

FIG. 5 is a longitudinal sectional view of a permanent magnet rotor according to another embodiment of the present invention. In addition to the embodiment shown in FIG. 1, flat nonmagnetic end plates 4 are provided on both end faces of the iron core 1 and fixed with clamp pins 5. The gap t between the inner diameter of the non-magnetic metal pipe 3 and the outer diameter of the end plate 4 is set to 0.2 mm or less. This is provided to prevent debris from falling outside the rotor, and it is better to have the gap t as small as possible (the magnet 2
It is set to 0.2rm or less in consideration of the thickness tolerance.

Effects of the Invention As is clear from the above embodiments, according to the present invention, the following effects can be obtained.

1. Cost effect a. Die-casting is not required, and not only expensive equipment is not required (and the material cost of molten metal is also not required).

b. Since die casting is not performed, the dimensional accuracy of the inner diameter of the iron core and the outer diameter of the non-magnetic metal pipe is good, and cutting is not required. Further, there is no need to remove molten metal burrs from die casting.

2. Effect on motor performance a. By shrink-fitting or press-fitting the non-magnetic metal pipe, there is no large gap between the iron core and the magnet, and between the magnet and the non-magnetic metal pipe as in conventional examples. Since only a small gap is generated between the contact surfaces of each component, the magnetic resistance of the magnetic circuit of the entire motor is reduced, and the amount of magnetic flux obtained increases accordingly, resulting in improved motor performance.

b. Since the outside diameter of non-magnetic metal pipes is not cut, it is possible to use a vibrator with a minimum wall thickness, which reduces the eddy current product generated in the pipe when the motor is operating. and improves motor performance.

As described above, the permanent magnet rotor according to the present invention can provide a high-performance motor at low cost, and has great effects.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of a permanent magnet rotor according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of a permanent magnet rotor according to an embodiment of the present invention, and FIG. 3 is a cross-sectional view of a permanent magnet rotor according to an embodiment of the present invention. FIG. 4 is a partially enlarged view showing the relationship between the outer diameter of the iron core and the dimension of the arcuate magnet according to an example, FIG. FIG. 6 shows a longitudinal cross-sectional view of a permanent magnet rotor according to another embodiment. 1... Laminated iron plate core or block iron core, 2...
... Arcuate magnet, 3 ... Non-magnetic metal pipe, 4.
...Flat non-magnetic end plate, 5... Clamp bin, DI... Arcuate magnet inner diameter dimension, DOY...
... Iron core outer diameter dimension, t ... Clearance between the inner diameter of the non-magnetic metal pipe 3 and the outer diameter of the flat non-magnetic end plate 4. Fig. Chikuba view

Claims (1)

[Claims] (1) In a permanent magnet rotor in which a plurality of arcuate magnets are arranged around the outer periphery of a laminated iron core or a block iron core, and non-magnetic metal pipes are shrink-fitted and press-fitted to the outer periphery of the plurality of magnets, the outer diameter of the iron core is Dimension D_0_Y and said arcuate magnet inner diameter dimension D_1_
The ratio with M is D_0_Y/D_1_M=0.999~0
．． 993, and at least one corner formed by an end face and an outer diameter face of the arcuate magnet is chamfered. 2 Flat non-magnetic end plates are provided on both end faces of the laminated iron core or the block iron core, and the gap between the inner diameter of the non-magnetic metal pipe and the outer diameter of the flat non-magnetic end plate when the rotor is completed is 0.2 mm or less. A permanent magnet rotor according to claim 1, characterized in that: