JPH019250Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to the structure of a rotor for a squirrel-cage induction machine that is used under severe operating conditions, such as medium capacity or higher capacity or particularly frequent startup.

It is desirable for the squirrel cage conductor of the rotor of a squirrel cage induction machine to withstand centrifugal force and heat caused by operation and to have a long life.

In the rotor of a conventional squirrel cage induction machine, as shown in Fig. 1, squirrel cage conductor bars 2 are inserted into slots of a rotor core 1 which is formed by punching out slots and laminating them.
Both ends thereof protrude from the iron core, and an annular end ring 3 is fixed to the ends. Current flows through the squirrel-cage conductor bar 2 and the end ring 3 during operation, and the squirrel-cage conductor bar 2 expands due to the heat generated by the resistance loss, so that the squirrel-cage conductor bar 2 extends in the axial direction and the diameter of the end ring 3 is expanded. The iron core itself also expands thermally, but the expansion coefficients of the iron core and conductor are different, and the conductor expands more. If the temperature rise is extremely large, the conductor will deform as shown by the chain line in the figure, and a large bending stress will be applied to the part of the squirrel-cage conductor bar 2 protruding from the iron core 1, which together with the centrifugal force caused by operation, may lead to damage. be. When the operation is stopped, the temperature of the end ring 3 decreases faster than that of the iron core, so the end ring contracts, and stress acts on the bar 2 toward the center.
Furthermore, the axial elongation of the conductor bar 2 due to thermal expansion is not uniform due to friction with the iron core and becomes jagged, so that a large bending stress is applied to the end ring 3 as well. In order to weaken the stress on the protruding part of the squirrel cage bar 2 from the iron core, it is possible to increase the length l of the protruding part, but this increases resistance loss, increases the required amount of conductor, and The drawback was that the stress applied to the ring was large.

The present invention eliminates the above-mentioned drawbacks, shortens the protruding length of the squirrel-cage conductor bar from the iron core, and allows the bar to expand and contract uniformly, reducing thermal stress on the bar and end ring. The purpose is to provide a rotor for

Next, embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a partial vertical sectional view of the rotor of a squirrel cage induction machine according to an embodiment of the present invention, and FIG.
A sectional view, FIG. 4 is a BB sectional view thereof. 1st
Parts indicated by the same numbers as in the figures are the same parts. A slot liner 4 is inserted into the slot of the rotor core 1, which is formed by punching and laminating slots, and is shaped like a thin sleeve and has a certain length notched at the top and bottom of both ends (i.e., both sides of the bottom surface of the slot and the surface facing it). A squirrel-cage conductor bar 2 is inserted surrounded by the slot liner 4, and end rings 3 are fixed to both ends thereof. When the length of the notch of the slot liner 4 from the end of the iron core is α, the length of the bar 2 protruding from the iron core 1 is l−α. The slot liner 4 is made of brass or copper plate, and functions to conduct heat of the bar 2 well to the iron core and to make the elongation of the bar 2 uniform. In this way, the length of the part of the bar 2 that is subjected to bending stress is l, which is sufficiently long to relieve the stress, and the part that protrudes from the iron core is l-α, making it possible to shorten the length of the protruding part. Moreover, the elongation due to thermal expansion of the bar can be made uniform.

According to the present invention, by inserting a squirrel cage conductor bar through a sleeve-like slot liner cut out at the top and bottom of the core end, the length of the bar protruding from the core is shortened, and the bending stress caused by the heat is alleviated. Moreover, since the elongation due to thermal expansion can be made uniform, the thermal stress of the end ring can be alleviated, reducing the cost.
It has the effect of increasing efficiency and reliability.

[Brief explanation of the drawing]

FIG. 1 is a partial vertical cross-sectional view of the rotor of a conventional squirrel-cage induction machine, FIG. 2 is a partial vertical cross-sectional view of the rotor of a squirrel-cage induction machine according to an embodiment of the present invention, and FIG.
A sectional view, and FIG. 4 is a BB sectional view thereof. 1...Rotor core, 2...Squirrel cage conductor bar, 3
...End ring, 4...Slot liner.

Claims (1)

[Scope of utility model registration request] A sleeve-like slot liner is installed in the slot of the rotor core, which is made by punching and laminating slots, surrounding the squirrel-cage conductor bar and cutting out both sides of the slot by a certain length from both ends of the core. A rotor for a squirrel-cage induction machine characterized by the following: