Patent ID: 7641171

Claim:
A fluid control valve comprising: a pressure chamber including an output port; an air supply nozzle and an air exhaust nozzle which are communicatively connected to said pressure chamber and positioned on a common straight line; a flapper assembly which is movable between said air supply nozzle and said air exhaust nozzle and includes a pair of opening/closing control surfaces that face an opening end of said air supply nozzle and an opening end of said air exhaust nozzle, respectively; and an electromagnetic drive mechanism which moves said flapper assembly so that a distance between said opening end of said air supply nozzle and one of said pair of opening/closing control surfaces increases while a distance between said opening end of said air exhaust nozzle and the other of said pair of opening/closing control surfaces decreases, wherein said electromagnetic drive mechanism comprises: a permanent magnet fixed to said flapper assembly, said permanent magnet being formed in a cylindrical columnar shape; and a fixed coil portion which produces an electromagnetic effect between said fixed coil-yoke portion and said permanent magnet to move said flapper assembly, wherein said flapper assembly comprises a pair of flappers including said pair of opening/closing control surfaces, respectively, wherein central portions of said pair of flappers are connected to each other via a connecting member which includes two magnet yokes positioned at opposite ends of said permanent magnet, wherein said fixed coil portion includes a pair of fixed coils which are positioned around said permanent magnet and said two magnet yokes to be symmetrical with respect to a central position of said flapper assembly; a pair of coil yokes positioned on opposite sides of said pair of fixed coils, respectively; and a pair of coil yokes positioned around said pair of fixed coils, respectively, wherein opposite end surfaces of said pair of coil yokes on said pair of flappers sides are positioned outside of outward end surfaces of said two magnet yokes, respectively, and wherein said fluid control valve is controlled so that directions of flow of currents passing through said pair of fixed coils become opposite to each other.