JP2000069719A - Rotor of permanent magnet type of rotating machine and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the structure of a rotor which can secure an enough interference even in case that a shrink ring made of FRP is used. SOLUTION: This rotor is equipped with a shrink ring 10 made of FRP, a permanent magnet 20 and spacer press-fitted in the shrink ring 10, a rotary shaft 30 made of metal, for example, iron, inserted into the shaft hole 20a of the permanent magnet 20, and a pair of balance plates 40 and 41 fixed to the rotary shaft 30 in such a way as to press the permanent magnet 20 and the shrink ring 10 from both sides in axial direction. The rotary shaft 30 has such an outside diameter as to have a specified interference at normal temperature to the shaft hole of a cylinder made of the permanent magnet 20 and the spacer, and it is inserted into this shaft hole in condition that it is shrunk by cooling. The permanent magnet 20 and the spacer are fixed firmly, being stuck fast to the shrink ring 10 by the expansion at the time of returning to normal temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a rotor of a rotating electric machine having a permanent magnet, and more particularly to a rotor having a shrink ring made of fiber reinforced plastic (FRP) and a method of manufacturing the rotor.

[0002]

2. Description of the Related Art The configuration shown in FIGS. 4 and 5 is known as a rotor of a conventional permanent magnet type rotating electric machine. FIG. 4 is a vertical sectional front view, and FIG. 5 is a sectional view taken along line AA of FIG. As shown in these figures, a permanent magnet 2 and a spacer 3 are arranged around a rotary shaft 1 having a large diameter at a central portion and small diameters at both ends so as to form a cylinder as a whole. A stainless steel shrink ring 4 for tightening and fixing them around the outer periphery of the and the spacer 3 is fitted.

At both ends of the shrink ring 4, a pair of balance plates 5a and 5b are provided fixed to the rotating shaft 1 so as to press the permanent magnet 2 and the shrink ring 4 from both sides in the axial direction. When assembling, the rotating shaft 1
The permanent magnet 2 and the spacer 3 are arranged around the shrink ring, and the shrink ring 4 is fitted around the outer periphery of the shrink ring 4 in an expanded state. The inner diameter of the shrink ring 4 is smaller than the outer diameter of the cylinder formed by the permanent magnet 2 and the spacer 3 at room temperature, and the shrink fit as described above secures interference by shrinkage force when returning to room temperature. Permanent magnet 2 and spacer 3
Are firmly fixed to the rotation axis.

[0004]

However, the stainless steel shrink ring 4 used in the above-mentioned conventional rotor has high heat resistance and stable strength, but has high conductivity and large eddy current loss. There was a problem. Thus, it has been proposed to use a shrink ring made of fiber reinforced plastic (FRP), which is somewhat inferior in strength but has low conductivity and low eddy current loss. However, since FRP has a low coefficient of thermal expansion, the shrink-fit as described above cannot be performed, a sufficient interference can not be secured by the same assembling method as before, the shrink ring is loosened at high speed rotation, and There is a possibility that the rotor will move and the rotational balance of the rotor will be lost, and a response has been required.

The present invention has been made in view of the above-mentioned problems of the prior art, and has a rotor structure capable of securing a sufficient interference even when a shrink ring made of FRP is used, and manufacturing the rotor. The aim is to provide a method.

[0006]

In order to solve the above-mentioned problems, a rotor of a permanent magnet type rotating electric machine according to the present invention has a fiber-reinforced plastic shrink ring and a cylindrical permanent magnet press-fitted into the shrink ring. The magnet, the metal rotary shaft inserted into the permanent magnet shaft hole in a state where the magnet has a predetermined interference at room temperature with respect to the shaft hole of the permanent magnet and is contracted by cooling, the permanent magnet and the shrink ring. And a pair of balance plates fixed to the rotating shaft so as to be pressed from both sides in the axial direction.

On the other hand, as a method for manufacturing a rotor of a permanent magnet type rotating electric machine according to the present invention, a cylindrical permanent magnet is press-fitted into a shrink ring made of fiber reinforced plastic, and is inserted into a shaft hole of the permanent magnet at room temperature. A metal rotating shaft having a predetermined interference is inserted into the shaft hole of the permanent magnet while being contracted by cooling, and after returning to room temperature, a pair of balance plates for pressing the permanent magnet and the shrink ring from both sides in the axial direction are formed. It is characterized by being fixed to a rotating shaft.

According to the above structure and method, instead of expanding and shrink-fitting an FRP shrink ring having a small thermal expansion coefficient, a metal rotating shaft having a large thermal expansion coefficient is shrunk by cooling to obtain a permanent. Insertion into the shaft hole of the magnet and expansion of the rotating shaft when returning to room temperature can secure interference. Therefore, a force from the inside to the outside is applied to the permanent magnet, whereby the permanent magnet can be brought into close contact with the shrink ring and firmly fixed.

[0009]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a permanent magnet type rotating electric machine according to an embodiment of the present invention. FIG. 1 is a vertical sectional front view, and FIG. 2 is a sectional view taken along line BB of FIG. As shown in these figures, the rotor of the present embodiment is inserted into a shrink ring 10 made of FRP, a permanent magnet 20 and a spacer 21 press-fitted in the shrink ring 10, and a shaft hole 20a of the permanent magnet 20. And a pair of balance plates 40 and 41 fixed to the rotating shaft 30 so as to press the permanent magnet 20 and the shrink ring 10 from both sides in the axial direction.

As shown in FIG. 2, the permanent magnet 20 is composed of two members divided in the circumferential direction, and a spacer 21 is fitted between them. The permanent magnet 20 and the spacer 21 form a cylindrical shape as a whole in a combined state, and are provided between the shrink ring 10 and the rotating shaft 30. The rotating shaft 30 has an outer diameter such that it has a predetermined interference at room temperature with respect to a cylindrical shaft hole 20a formed by the permanent magnet 20 and the spacer 21, and the shaft hole 20a is contracted by cooling. And the permanent magnet 20 and the spacer 21 are tightly fixed to the shrink ring 10 by expansion when returning to room temperature.

Next, a manufacturing process of the rotor of the present invention will be described with reference to FIG. First, in the first step, FIG.
As shown in (A), a jig 50 smaller in diameter than the rotating shaft 30 is fitted into a cylindrical member formed by combining the permanent magnet 20 and the spacer 21, and the jig 50 is held while holding the jig 50. The outer surfaces of the permanent magnet 20 and the spacer 21 are machined such that the shrink ring 10 is a stop fit, that is, in this example, the outer diameter of the permanent magnet 20 substantially matches the inner diameter of the shrink ring 10. In the second step, as shown in FIG. 3B, the jig 50 is extracted, and the permanent magnet 20 and the spacer 21 are pressed into the shrink ring 10. In this state, the shaft hole 2 of the permanent magnet 20 is set so that an appropriate interference occurs between the rotating shaft 30 and the rotating shaft 30 at room temperature.
The surface of Oa is processed.

In the third step, as shown in FIG.
The rotating shaft 30 is contracted by cooling using liquid nitrogen or the like,
In a contracted state, it is inserted into the shaft hole 20a of the permanent magnet 20. The assembly of the permanent magnet 20 and the shrink ring 10 is placed upright on a worktable 60 in which an opening 61 through which one end of the rotating shaft 30 passes is formed.
0 is inserted. After inserting the rotating shaft 30, the rotating shaft 30
Let it return to room temperature. The rotating shaft 10 is designed to have a predetermined interference with the shaft hole 20a of the permanent magnet 20 at room temperature.
The permanent magnet 20 and the spacer 21 are brought into close contact with the shrink ring 10 by applying a force from the inside to the outside of the spacer and the spacer 21. In the fourth step, after the rotating shaft 30 returns to room temperature, as shown in FIG.
0 and 41 are fixed to the rotating shaft 30 by shrink fitting.

[0013]

According to the constitution and method of the present invention, after a rotating shaft having an appropriate interference at room temperature is cooled and inserted, the temperature is returned to room temperature, so that there is no proper space between the rotating shaft and the permanent magnet. The margin can be secured. Therefore, even when a shrink ring made of FRP that cannot be shrink-fitted is used, the permanent magnet can be brought into close contact with the shrink ring from inside due to expansion of the rotating shaft, and eddy current loss is small.
In addition, it is possible to provide a rotor in which the permanent magnet is firmly fixed to the rotating shaft.

[Brief description of the drawings]

FIG. 1 is a vertical sectional front view of a rotor of a permanent magnet type rotating electric machine according to one embodiment of the present invention.

FIG. 2 is a sectional view taken along line BB of FIG.

FIG. 3 is an explanatory view showing a manufacturing process of the rotor of FIG. 1, wherein FIG. 3A shows the first process, FIG. 3B shows the second process, and FIG. These are shown respectively.

FIG. 4 is a vertical sectional front view of a rotor of a conventional permanent magnet type rotating electric machine.

FIG. 5 is a sectional view taken along line AA of FIG. 4;

[Explanation of symbols]

 10: Shrink ring 20: Permanent magnet 20a: Shaft hole 21: Spacer 30: Rotating shaft 40, 41: Balance plate

Claims (2)

[Claims] 1. A shrink ring made of fiber reinforced plastic, a cylindrical permanent magnet press-fitted in the shrink ring, and a predetermined interference at a normal temperature with respect to a shaft hole of the permanent magnet. A metal rotary shaft inserted into the shaft hole of the permanent magnet in a contracted state, and a pair of balance plates fixed to the rotary shaft so as to press the permanent magnet and the shrink ring from both sides in the axial direction. A rotor for a permanent magnet type rotating electric machine, comprising: 2. A cylindrical permanent magnet is press-fitted into a fiber-reinforced plastic shrink ring, and a metal rotating shaft having a predetermined interference at room temperature is shrunk by cooling into a shaft hole of the permanent magnet. A pair of balance plates that press the permanent magnet and the shrink ring from both sides in the axial direction after being inserted into the shaft hole of the permanent magnet in a state of being returned to normal temperature, and fixed to the rotating shaft. For manufacturing a rotor for a rotary electric machine.