US 5,731,651 AGranted

Rotor for an electromotive tool motor

AssigneeMakita Corporation

InventorKouki Hyodo

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Abstract

A motor rotor for use in a grinder or other electromotive tool in which a motor winding is prevented from being damaged by collisions with particles. The motor rotor is composed of a core having sixteen teeth extending radially relative to a rotation shaft and slots formed among the teeth, a coil of winding wound around the slots, and wedge members for covering the slots. Felt strip members are wound around the parts of the coil exposed at both ends of the core before the exposed parts are impregnated with varnish. Varnish also permeates the strip members, and the strip members are firmly adhered to the exposed parts of the coil. After the varnish dries, the strip members fix themselves and are provided with a strength equal to that of plastic. The ribs provided by the strip members act as fins blowing away any particles, thereby protecting the coil from damage from the particles.

Claims14

Dependent claims

A rotor for an electric motor, comprising:

a) a rotary shaft;
b) a core having a plurality of slots extending longitudinally along said rotary shaft;
c) a coil extending along the plurality of slots of said core and having opposite end portions extending beyond said core;
d) a material for impregnating and solidifying said coil;
and
e) a ribbed strip member formed from a pliable sheet highly permeable to said material, said ribbed strip member comprising a plurality of ribs provided in an axial direction relative to said rotor, each rib having a first end and a second end, a first strip interconnecting the first ends of said ribs, and a second strip interconnecting the second ends of said ribs;
f) said ribbed strip member being wound around the end portions of said coil such that said first strip is closer to the periphery of said coil and said second strip is closer to the periphery of said rotary shaft, said first strip having a length substantially equal to the peripheral circumference of said coil, said second strip having a length substantially equal to the peripheral circumference of the rotary shaft, where said ribbed strip member is impregnated with said material such that said ribbed strip member is firmly adhered to said end portions of said coil.

4 more elements

Dependencies are inferred from the claim text.