US3586893A

US3586893A - Armature core

Info

Publication number: US3586893A
Application number: US871852A
Authority: US
Inventors: Harumichi Okamoto; Kiyoshi Fukui; Teruo Oshima
Original assignee: Tokyo Shibaura Electric Co Ltd
Current assignee: Toshiba Corp
Priority date: 1968-11-02
Filing date: 1969-10-28
Publication date: 1971-06-22
Anticipated expiration: 1988-06-22
Also published as: JPS5322456B1

Abstract

A moulded armature core comprises a moulded cylindrical block of magnetic material, having a plurality of slots disposed in parallel along the peripheral portion thereof in a manner to extend lengthwise of the block, said slots being so tapered as to progressively decrease in both depth and width.

Description

United States Patent [72] Inventors HarumichiOkamoto;

Kiyoshi Fukui; Teruo Oshima, all 01 Yokohama-shi, Japan [21] Appl.No. 871,852

[22] Filed Oct. 28,1969

145 Patented June 22, 1971 {73] Assignee Tokyo Sllibaura Electric Co., Ltd.

Tokyo, Japan [32] Priority Nov. 2,1968

[S4] ARMATURE CORE 2 Claims, 7 Drawing Figs.

[52] U.S.Cl 310/166, 3101211, 310/265 [51] Int. Cl H02k U26 [50] Field ofSearch 310/261, 264,265,216, 193, 194,211, 166, 179, 180,214,

[56] References Cited UNITED STATES PATENTS 2,662,820 12/1953 Crome 75/123 X FOREIGN PATENTS 397,049 2/1966 Switzerland 310/193 575,413 5/1959 Canada 310/211 Primary Examiner-D. F. Duggan Attorney-Flynn & Frishauf ABSTRACT: A moulded armature core comprises a moulded cylindrical block of magnetic material, having a plurality of slots disposed in parallel along the peripheral portion thereof in a manner to extend lengthwise of the block, said slots being so tapered as to progressively decrease in both depth and width.

PATENT-ED JUN22 19m FIG. 2'

FIG. 7

g ARMATURE coma BACKGROUND or THE INVENTION The present invention relates to an armature core of an induction motor, and particularly to an armature core formed from magnetic material into a block.

The prior art armature core is constructed by causing many disc plates perforated with slots along the peripheral portion thereof to be superposed on each other. Since such construction requires many manufacturing steps and consequently a great deal of time, it has been proposed that the armature core be formed into a cylindrical block.

SUMMARY OF THE INVENTION An object of this invention is to provide an annature core comprising a cylindrical block of magnetic material and a plurality of slots disposed parallel along the peripheral portion of said block in a manner to extend lengthwise, said slots being so tapered as to progressively decrease in both depth and width.

In this case, said slots may be of a partly closed type. Furthermore, the cylindrical block may be made of ferroalloy consisting of 2.03.5 percent carbon, 2.0-3.0 percent silicon and 0.050.l percent manganese, all by weight, and iron and impurities as the remainder. At the time of alloying said carbon is dispersed in the form of spherulitic graphite.

The features and advantages of this invention will be understood from the description with reference to the accompanying drawing.

BRIEF EXPLANATION OF THE DRAWING FIG. 1 is a plan view of an annature core according to this invention;

FIG. 2 is a cross-sectional view of said armature core taken along 'a line Il-II of Fig. I;

FIG. 3 is a plan view of another armature core according to this invention;

FIG. 4 is a cross-sectional view of said armature core taken along a line lV-IV of FIG. 3;

.FIG. 5 is a side view of an assembly of two annature cores of this invention;

FIG. 6 is a cross-sectional view of part of a preliminarily fabricated core; and

FIG. 7 is a cross-sectional view of part of a finished core.

DETAILED DESCRIPTIONv OF THE INVENTION FIGS. I and 2 indicate an armature core embodying this invention. Said armature core consists of a cylindrical block 1 of magnetic material such as iron or ferroalloy, and a plurality of slots 2 disposed in parallel along the outer peripheral portion of said block 1 in a manner to extend lengthwise of the block. Each of said slots 2 has a bulb-shaped cross section, so maybe called a partly closed slot. Further, said slot 2 is so tapered as to progressively decrease in both depth and width. Said cylindrical block 1 is easily formed by a simple moulding or diecasting process.

Preferably, said armature core or block is made of ferroalloy consisting of 2.0-3.5 percent carbon, 2.0-3.0 percent silicon and 005-0.] percent manganese, all by weight, and iron and impurities as the remainder. At the time of alloying said carbon is dispersed in the form of spherulitic graphite. Said armature core can display the same efficiency as that of the armature core generally constructed of a plurality of disc plates superposed on each other.

FIGS. 3 and 4 illustrate another type of armature core of this invention. Said armature core consists of a hollow cylindrical block 11 of ferroalloy, and a plurality of slots 12 disposed in parallel along the inner peripheral portion of said block I]. Said slots 12 are also so tapered as to progressively decrease in both depth and width.

FIG. 5 indicates a combination of two armature cores 21a and 21b. Said

cores

21a and 21b are connected by means of rotor shaft 23, in such a manner that the slots 22a of the core tapered in opposite directions.

In order to form a slot having a bulb-shaped cross section,

' the cylindrical block 1 (11 or 21) is first moulded so as to allow a plurality of U-shaped cross-sectional slots 32 to be integrally formed therewith, each of which is, of course, so tapered as to progressively decrease in both depth and width. Between the adjacent ones of said slots 32 is defined a longitudinal protrusion 35 which is provided at the top with a groove 36 having an arched cross section and extending lengthwise. Then, the cross section of the initially formed slots 32 is reshaped into a bulb-shape by depressing the lateral edges of said protrusion by hammering. In this case, the groove 36 permits the protrusion 35 to be easily depressed.

We claim:

1. A moulded armature core comprising a moulded cylindrical block of magnetic material having a plurality of tapered slots disposed substantially in parallel along the peripheral both depth and width along the length of said block, the

cross section of said slots being dimensionally varied at a predetermined rate in the lengthwise direction of said block; and

a shaft on which said armature cores are mounted such that the slots of said first armature core are displaced a halfpitch with respect to the slots of said second armature core, and such that the slots of said first and second armature cores are tapered in opposite directions.

Claims

1. A moulded armature core comprising a moulded cylindrical block of magnetic material having a plurality of tapered slots disposed substantially in parallel along the peripheral portion of said block and extending lengthwise of said block, said slots being tapered so as to progressively decrease in both depth and width along the length of said block.

2. An armature assembly for an induction motor comprising: first and second moulded armature cores each of said armature cores comprising a moulded cylindrical block of magnetic material having a plurality of tapered slots disposed substantially in parallel along the peripheral portion of said block and extending lengthwise of said block, said slots being tapered so as to progressively decrease in both depth and width along the length of said block, the cross section of said slots being dimensionally varied at a predetermined rate in the lengthwise direction of said block; and a shaft on which said armature cores are mounted such that the slots of said first armature core are displaced a half-pitch with respect to the slots of said second armature core, and such that the slots of said first and second armature cores are tapered in opposite directions.