JPS61132063A - Rotor of induction motor - Google Patents

Abstract

PURPOSE:To prevent a shortcircuiting ring from deforming due to centrifugal force and thermal stress by using as a reinforcing ring member a member having the prescribed thermal conductivity and strength. CONSTITUTION:A rotational shaft 3 is rotatably supported by a bearing, and a rotor 4 made of laminated electric steel plates is secured to the shaft 3. A rotor winding 5 is shortcircuited by a ring-shaped shortcircuiting ring 2 at the axial end of the rotor shaft. The ring 2 is bonded to a reinforcing ring 1 shrink-fitted to the shaft 3 by an inload. The material of the ring 1 has a weight lighter than an austenite stainless steel, good thermal conductivity, substantially equal thermal expansion coefficient to the ring 2 and a strength larger than the ring 2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a rotor for an induction motor having a reinforcing ring for preventing deformation of a short-circuit ring.

[Conventional technology and problems]

Conventionally, reinforcing rings for suppressing the deformation of the short-circuit ring caused by centrifugal force and thermal stress in the rotor of induction motors are: (1) non-magnetic; (2) strong; and (2) inexpensive and easily available. Austenitic stainless steel has generally been used because it is easy to process and has good temperature characteristics in terms of creep and other strength.

However, there are the following problems.

force) When the circumferential speed reaches high speeds exceeding 160 m/s,
Reinforcement ring? Since the specific gravity is large, the reinforcing ring itself undergoes plastic deformation due to its own centrifugal force, making it difficult to suppress the plastic deformation of the short-circuit ring.

As a result, both the reinforcing ring and the short-circuit ring become deformed and become unusable.

g) When aluminum or its alloy is used as the material for the short-circuit ring, due to the difference in thermal expansion coefficient between austenitic stainless steel and aluminum, expansion of the short-circuit ring is prevented by the reinforcing ring during low-speed rotation at product temperature, resulting in compression. At low temperature and high speed rotation, conversely, the short circuit ring undergoes tensile plastic deformation due to centrifugal force.

That is, when tensile and compressive plastic deformation are repeated alternately, the short ring undergoes low cycle fatigue failure.

ri) A high-speed motor has a much larger mechanical loss on the secondary side than a general-purpose motor, so the loss on the secondary side is large. A large portion of the loss generated on the secondary side is transmitted from the rotor core to the shaft, and the heat is carried away to the outside by means such as liquid cooling.

However, since austenitic stainless steel has poor thermal conductivity, less heat is carried away from the reinforcing ring through the shaft, making it unfavorable for cooling.

(Object of the Invention) An object of the present invention is to provide a rotor for an induction motor equipped with a reinforcing ring capable of overcoming the drawbacks of conventional devices and preventing deformation of the short-circuit ring due to centrifugal force or thermal stress. shall be.

(Summary of the Invention) The present invention provides for each [j! A member of the reinforcing ring, which is connected to a ring-shaped shorting ring that shorts the trochanter winding, and a reinforcing ring that is joined by a spigot and is fitted and fixed to the rotating shaft by shrink fit to reinforce the deformation of the shorting ring due to rotation. The rotor of the induction motor uses a material that is lighter than austenitic stainless steel, has better thermal conductivity, has the same coefficient of thermal expansion as the short-circuit ring, and has a stronger surface than the short-circuit ring.

(Embodiment) A side sectional view of one end surface of the rotor in the upper half of the rotating shaft in an embodiment of the present invention.

The rotating shaft 3 is rotatably supported by a bearing (not shown),
8! The rotor 4 made of electrical steel plate is fixed to the rotating shaft 3, and the rotating pre-winding $15 is short-circuited by a ring-shaped short circuit [2] at the end face in the axial direction of the rotor. It is joined with the reinforcing ring 1 which is firmly fitted and in-loaded,
Deformation of short circuits caused by centrifugal force and thermal stress is suppressed.

-The present invention is therefore an induction motor rotor having a reinforcing ring made of a material that satisfies the following conditions.

That is, (s)) As the material of the reinforcing ring 1, a material with a specific gravity smaller than that of austenitic stainless steel is used.

This reduces centrifugal force, increasing strength and increasing speed.

c) For the material of the reinforcing ring 1, use a material with better thermal conductivity than austenitic stainless steel.

This increases heat conduction from the reinforcing ring 1 to the rotating shaft 3, improving cooling characteristics and increasing speed.

S) Use materials that have the same coefficient of thermal expansion as the material for reinforcing ring 1 and the material for shorting ring 2.

This reduces the thermal stress of the short circuit ring 2, improves the low cycle fatigue life due to repetition of high temperature low speed and low temperature island speed, and allows the short circuit ring 2 to have a long life.

c) For the reinforcing ring 1 material, use a material that is stronger than the short circuit ring 2 material.

This increases the strength of the short-circuit ring 2.

Therefore, in this embodiment, when the short-circuit fFi2 material is aluminum, a duralumin-based material is used. ' An example of this effect is shown in Table 1.

Table 1 Effect of super duralumin reinforcing ring (calculation II
(Effects of the Invention) Thus, according to the present invention, since the specific gravity is small, plastic deformation does not occur during high-speed rotation, so high speeds can be achieved. It has a long low cycle fatigue life, and has good thermal conductivity, so the rotor temperature does not rise, and it is also highly stiff, making it ideal for preventing deformation of the shorted ring due to centrifugal force and thermal stress. A rotor for an induction motor can be obtained, which will greatly benefit this field.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of a main part of an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Reinforcement ring, 2... Short circuit ring, 3... Rotating shaft, 4... Rotor, 5... Rotor winding.

Claims (1)

[Claims] 1. Short-circuiting rings formed in a ring shape that short-circuit each rotor winding on both end faces of the rotor in the direction of the rotational axis are joined by a spigot, and are fitted onto the rotational shaft and fixed by shrink fit. In the reinforcing ring that reinforces the deformation of the short-circuit ring due to rotation, the reinforcing ring is made of a material that is lighter than austenitic stainless steel, has better thermal conductivity, and has approximately the same coefficient of thermal expansion as the short-circuit ring, and is stronger than the short-circuit ring. A rotor for an induction motor characterized by using a large material.