Commutator motor

Abstract

A commutator motor includes a stator and a rotor, and the stator includes a stator yoke and a field magnet. The field magnet is fixed onto the inner peripheral surface of the substantially cylindrical stator yoke. The stator yoke is configured by coaxially stacking a plurality of plate-like annular bodies, and the annular bodies are fixedly connected to each other by caulking at a caulking portion disposed on the annular body. In manufacture, the length of the stator yoke in the axial direction can be arbitrarily changed with the thickness of the annular body in the axial direction as a minimum unit. In case of manufacturing various stator yokes that are different in the axial length, the necessity of replacing a manufacturing machine is eliminated, thereby providing a commutator motor having the stator yoke which is low in the manufacturing costs.

1 . A commutator motor, comprising: 
 a stator comprising a stator yoke have a tubular shape and extending in an axial direction and having an inner peripheral surface, and a field magnet fixed to the inner peripheral surface of the stator yoke for providing a field magnetic pole in the stator, and    an armature rotatably disposed within the stator;    wherein the stator yoke comprises at least one of (a) a plurality of plate-like annular bodies having iron parts which are stacked on each other coaxially in the axial direction of the stator yoke, and (b) a plurality of substantially identically configured iron plate-like arcuate bodies disposed at such position as to form a part of virtual annular bodies and which are stacked on each other coaxially in the axial direction of the stator yoke;    wherein the plurality of plate-like annular bodies or the plate-like arcuate bodies adjacent to each other in the stacked direction are fixedly connected to each other by caulking; and    wherein at least one pair of convex portions protrude radially inwardly from the inner peripheral surface of the stator yoke, each convex portion having a size in a circumferential direction of the stator yoke and in a radial direction thereof to allow plastic deformation of each convex portion for directly holding securely the permanent field magnet positioned between the convex portions in the circumferential direction.    
   
   
       2 . The commutator motor as claimed in  claim 1 , wherein the plurality of plate-like annual bodies or the plate-like arcuate bodies have an inner peripheral surface defining the inner peripheral surface of the stator yoke.  
   
   
       3 . The commutator motor as claimed in  claim 1 , wherein the at least one pair of convex portions is disposed at positions of end portions of the permanent field magnet and the permanent field magnet is press-inserted between the at least one pair of convex portions so as to be held therebetween.  
   
   
       4 . The commutator motor as claimed in  claim 3 , wherein the at least one pair of convex portions provides a distance therebetween in the circumferential direction of the stator core, and the permanent field magnet has a length in the circumferential direction greater than the distance prior to holding of the permanent field magnet between the pair of convex portions.  
   
   
       5 . The commutator motor as claimed in  claim 3 , wherein the at least one pair of convex portions provides a distance therebetween in the circumferential direction of the stator core, and the permanent field magnet has a length in the circumferential direction smaller than the distance prior to holding of the permanent field magnet between the pair of convex portions.  
   
   
       6 . The commutator motor as claimed in  claim 1 , wherein the at least one pair of convex portions are linearly arrayed in an axis direction of the stator yoke on an inner peripheral surface thereof.  
   
   
       7 . The commutator motor as claimed in  claim 1 , wherein the plurality of plate-like annular bodies or the plate-like arcuate bodies each have a concave portion and are fixedly connected to each other by caulking the concave portion and mating to a convex portion of an adjacent one of the plurality of plate-like annual bodies or the plate-like arcuate bodies.  
   
   
       8 . A commutator motor, comprising: 
 a stator comprising a stator yoke having a tubular shape and extending in an axial direction and having an inner peripheral surface, and a permanent field magnet fixed to the inner peripheral surface of the stator yoke for providing a field magnetic pole in the stator; and    an armature rotatably disposed within the stator;    wherein the stator yoke comprises at least one of (a) a plurality of plate-like annular bodies having iron parts which are stacked on each other coaxially in the axial direction of the stator yoke, and (b) a plurality of substantially identically configured iron plate-like arcuate bodies disposed at such position as to form a part of virtual annular bodies and which are stacked on each other coaxially in the axial direction of the stator yoke;    wherein the plurality of plate-like annular bodies or the plate-like arcuate bodies adjacent to each other in the stacked direction are fixedly connected to each other by caulking; and    wherein at least one pair of convex portions protrude radially inwardly from the inner peripheral surface of the stator yoke, each convex portion being plastically deformed for directly holding securely the permanent field magnet positioned between the convex portions in the circumferential direction.