Motor-operated flow control valve and exhaust gas recirculation control valve for internal combustion engine

Abstract

Disclosed is a motor-operated flow control valve for internal combustion engines which has a longer useful life and does not cause a drop of torque generated by a motor at the start-up. A rotor shaft ( 9 ) is reciprocated with rotating motion of a motor ( 32 ), whereupon a valve head ( 2 a ) is moved to open and close an orifice for control of a flow rate. Specific frequency of a rotor unit ( 33 ) of the motor ( 32 ) is set to be higher than the secondary vibration frequency of rotation of a 4-cycle internal combustion engine. The rotor unit ( 33 ) comprises an integral magnet ( 25 ), a single ball bearing ( 27 ) and a resin-made magnet holder ( 26 ) for supporting these two members, the magnet, the ball bearing and the magnet holder being formed into an integral structure. The rotor unit is supported such that an outer race ( 27 c ) of the ball bearing ( 27 ) is held at its one end against an inner peripheral wall of a housing resin ( 14 ) and a preload is applied to the other end of the outer race ( 27 c ).

What is claimed is:  
     
         1 . A motor-operated flow control valve comprising a rotor shaft reciprocating with rotating motion of a motor, and a valve head movable to open and close an orifice with the reciprocating motion of said rotor shaft, wherein: 
 specific frequency of a rotor unit of said motor is set to be higher than the secondary vibration frequency of rotation of a 4-cycle internal combustion engine.    
     
     
         2 . A motor-operated flow control valve according to  claim 1 , wherein said rotor unit comprises an integral magnet, a single ball bearing and a resin-made magnet holder for supporting said magnet and said ball bearing, said magnet, said ball bearing and said magnet holder being formed into an integral structure.  
     
     
         3 . A motor-operated flow control valve comprising a rotor shaft reciprocating with rotating motion of a motor, and a valve head movable to open and close an orifice with the reciprocating motion of said rotor shaft, wherein: 
 a rotor unit of said motor comprises an integral magnet, a single ball bearing and a magnet holder for supporting said magnet and said ball bearing, said ball bearing having an outer race held fixed under a preload.    
     
     
         4 . A motor-operated flow control valve comprising a rotor shaft reciprocating with rotating motion of a motor, and a valve head movable to open and close an orifice with the reciprocating motion of said rotor shaft, wherein said valve comprises a motor, a valve body for supporting said valve head, and a body joining said motor and said valve body together and having a cooling water passage formed therein, and 
 the outer race of said ball bearing is held in place astride between a case of said motor and said body.    
     
     
         5 . A motor-operated flow control valve comprising a rotor shaft reciprocating with rotating motion of a motor, and a valve head movable to open and close an orifice with the reciprocating motion of said rotor shaft, wherein said valve comprises a motor, a valve body for supporting said valve head, and a body joining said motor and said valve body together and having a cooling water passage formed therein, and 
 the outer race of said ball bearing is held in place by said body.    
     
     
         6 . A motor-operated flow control valve according to  claim 5 , wherein an end face of the outer race of said ball bearing is held in place through a washer in the axial direction of said rotor shaft.  
     
     
         7 . A motor-operated flow control valve according to  claim 5 , wherein a cooling water passing through said cooling water passage is a cooling water for an internal combustion engine.  
     
     
         8 . A motor-operated flow control valve according to  claim 5 , wherein said valve is an exhaust gas recirculation control valve.