Motor case

Abstract

In a motor case 1 , recesses 8 are formed in inner surfaces of upper and bottom surface portions 2 and 3 (which are spaced from each other by a distance smaller than the distance between left and right side surface portions 4 and 5 ), thus reducing the thickness of these surface portions 2 and 3 , thereby increasing a space for receiving a stator coil 10 as much as possible. Unlike a construction in which a stator coil is exposed through openings formed in a motor case, the stator coil is covered with the motor case, and therefore the motor is excellent in shielding performance and impact resistance. The motor case 1 has a square tubular shape, and can be formed by blanking, press-forging (for the purpose of forming the recesses) and bending a metal sheet, and the motor case can be produced at a low cost.

1 . A motor case, comprising: 
 an inner surface, defining a chamber in which a stator coil and a rotor are housed;    wherein a concave portion is formed on at least a part of an area of the inner surface which is brought into contact with the stator coil so as to increase a space for housing the stator coil.    
   
   
       2 . The motor case according to  claim 1;  wherein: 
 the inner surface comprises: 
 at least one flat portion on which the concave portion is formed.  
   
   
   
       3 . The motor case according to  claim 2;  wherein: 
 the inner surface comprises: 
 two of the flat portions; opposed to each other.  
   
   
   
       4 . The motor case according to  claim 3 , wherein: 
 the motor case has a square tubular shape; and    the inner surface includes a side surface interconnecting the two of flat portions.    
   
   
       5 . The motor case according to  claim 1 , wherein: 
 the motor case is formed by a metal sheet blanked into a shape corresponding to a developed shape of the motor case;    the concave portion is formed in the metal sheet by press-forging, or cutting; and    the metal sheet is fabricated into the shape of the motor case by bending or drawing.    
   
   
       6 . The motor case according to  claim 5 , wherein: 
 the flat portion is divided into two sections in case such that the metal sheet is the developed form; and    the two sections jointly form one continuous flat surface in case of fabricating the metal sheet by bending or drawing.