Small-size motor

Abstract

A shaft having a diameter A is press-fitted into the central hole of the boss. A tapered portion is formed around one end of the shaft, which is inserted to the center hole, such that a dimension in the extending direction of the shaft is R. The boss includes a cylindrical recess formed concentrically with the center hole on one end face thereof facing a side from which the shaft is inserted such that a dimension in the extending direction of the center hole thereof is larger than R, and such that a diameter thereof is A<B≦1.05A. The cylindrical recess includes a first side wall linearly extending from the end face of the boss and a second side wall subsequent to the first side wall, which is tapered inwardly in order to serve as an insertion guide member against which the tapered portion of the shaft is to be abutted when the shaft is inserted into the center hole. A wall member is formed on one end face of the boss so as to face the bearing with a gap having a predetermined width in between for blocking lubricant oil splashed from a sintered oil-contained bearing for supporting the shaft.

What is claimed is:  
     
         1 . A motor comprising: 
 a boss having a center hole; and    a shaft press-fitted into the center hole, a diameter of which is A,    wherein a tapered portion is formed around one end of the shaft, which is inserted to the center hole, such that a dimension in the extending direction of the shaft is R; and    wherein the boss includes a cylindrical recess formed concentrically with the center hole on one end face thereof facing a side from which the shaft is inserted such that a dimension in the extending direction of the center hole thereof is larger than R, and such that a diameter thereof is A<B≦1.05A.    
     
     
         2 . The motor as set forth in  claim 1 , wherein the cylindrical recess includes a first side wall linearly extending from the end face of the boss and a second side wall subsequent to the first side wall, which is tapered inwardly in order to serve as an insertion guide member against which the tapered portion of the shaft is to be abutted when the shaft is inserted into the center hole.  
     
     
         3 . The motor as set forth in  claim 2 , further comprising a rotor case integrally provided with the boss, 
 wherein the shaft serves as a rotary shaft of the motor.    
     
     
         4 . The motor as set forth in  claim 3 , wherein the rotor case includes a supporting face on which a disk rotated is to be disposed.  
     
     
         5 . The motor as set forth in  claim 3 , wherein a caulking member is provided on at least one end face of the boss so as to surround the center hole, which is to be compressed onto the shaft inserted into the center hole.  
     
     
         6 . The motor as set forth in  claim 3 , further comprising: 
 a sintered bearing for supporting the shaft, in which lubricant oil is contained; and    a wall member formed on one end face of the boss so as to face the bearing with a gap having a predetermined width in between for blocking the lubricant oil splashed from the bearing.    
     
     
         7 . The motor as set forth in  claim 6 , wherein the blocking wall member extends in a direction of which the center hole extends so as to surround an outer circumferential face of the bearing; and 
 wherein the gap between the blocking wall member and the outer circumferential face of the bearing is determined to such an extent that the splashed lubricant oil attached to the blocking wall and depended therefrom can adhere again onto the outer circumferential wall of the bearing.    
     
     
         8 . A motor comprising: 
 a boss having a center hole;    a shaft press-fitted into the center hole;    a sintered bearing for supporting the shaft, in which lubricant oil is contained;    a holder for holding the bearing; and    a wall member formed on one end face of the boss so as to face the bearing with a gap having a predetermined width in between for blocking the lubricant oil splashed from the bearing.    
     
     
         9 . The motor as set forth in  claim 8 , wherein one end face of the boss faces one end face of the bearing; and 
 wherein an annular recess is formed on the end face of the boss such that outer circumferential wall of the annular recess serves as the blocking wall member.    
     
     
         10 . The motor as set forth in  claim 9 , wherein the outer circumferential wall of the annular recess is arranged inner than an outer circumferential wall of the holder.  
     
     
         11 . The motor as set forth in  claim 8 , wherein the blocking wall member extends in a direction of which the center hole extends so as to surround an outer circumferential face of the bearing; and 
 wherein the gap between the blocking wall member and the outer circumferential face of the bearing is determined to such an extent that the splashed lubricant oil attached to the blocking wall and depended therefrom can adhere again onto the outer circumferential wall of the bearing.    
     
     
         12 . The motor as set forth in  claim 8 , wherein oil repellant finishing is applied onto the inner face of the blocking wall member.