Direct current commutator motor

Abstract

A DC commutator motor that is driven by a direct current power source obtained by rectifying an alternating current power source includes a plus-side brush made of material having a high resistivity and a minus-side brush made of material having a low resistivity. A capacitor is inserted in and connected parallel to the direct current power source. The commutator motor makes use of specials tubes having different shapes to avoid an incorrect insertion of one of the specials tubes into the insertion hole designed to receive the other of the specials tubes.

What is claimed is:  
     
         1 . A direct current commutator motor which comprises: 
 first and second specials tubes made of metal and for slidingly receiving first and second brushes of different material, respectively; and    a bracket made of a synthetic resin and having first and second insertion holes for receiving and retaining in position the first and second specials tubes, respectively;    wherein the first and second specials tubes are so shaped relative to the first and second insertion holes that the first specials tube and the second specials tube can be snugly inserted into the first and second insertion holes, respectively, but the first and second specials tube cannot be inserted into the second and first insertion holes, respectively.    
     
     
         2 . The direct current commutator motor as claimed in  claim 1 , 
 wherein the first specials tube has first and second projections formed thereon with the second projection positioned at a location spaced a first predetermined angle from the first projection as viewed from an opening of the first specials tube, and the first insertion hole for receiving the first specials tube has first and second grooves defined therein at respective locations alignable with the first and second projections on the first specials tube to allow the latter to be inserted into the first insertion hole with the opening of the first specials tube oriented towards the first insertion hole;    wherein the second specials tube has third and fourth projections formed thereon with the fourth projection positioned at a location spaced a second predetermined angle from the third projection as viewed from an opening of the second specials tube, and the second insertion hole for receiving the second specials tube has third and fourth grooves defined therein at respective locations alignable with the third and fourth projections on the second specials tube to allow the latter to be inserted into the second insertion hole with the opening of the second specials tube oriented towards the second insertion hole; and    wherein the first and second predetermined angles are different from each other.    
     
     
         3 . A direct current commutator motor which comprises: 
 a bracket made of a thermosetting resin and having insertion holes defined therein;    a specials tube made of metal and adapted to be inserted into and retained in position within a corresponding one of the insertion holes, said specials tube having tab provided on a side face thereof, said tab having a bendable portion left by a crevice defined in the tab; and    a brush slidably accommodated within the specials tube;    wherein the insertion hole has a groove defined therein for receiving the tab on the specials tube when the latter is inserted into and retained in position inside the insertion hole with the bendable portion exposed to the outside, said groove being of a size sufficient to provide a slight gap between it and the tab, said bendable portion being, after the specials tube has been inserted into the insertion hole, being deformed to bend.