Patent ID: 6325102
Filing Date: 2001-12-04
Classification: F15B,Y10T

Abstract:
A servo driving pilot-type solenoid valve, comprising:a main valve portion including a plurality of ports, a valve hole which is in communication with said ports, and a flow path switching valve member slidably inserted into said valve hole;a pilot driving mechanism including a pushing member disposed in one end of said valve member, and a pilot valve for supplying a pilot fluid to said pushing member, said pilot driving mechanism switching said valve member by said pushing member which is operated by a pilot fluid pressure; anda returning mechanism for applying a returning force caused by at least one of a fluid pressure and a spring to the other end of said valve member, wherein,said pushing member in said pilot driving mechanism comprises, a first piston operated by the pilot fluid pressure from said pilot valve, and a second piston having substantially the same diameter as that of said first piston and operated by the pilot fluid pressure and a pushing force by said first piston,said first piston includes a shaft which air-tightly passes through a partition wall which divides both said pistons from each other and whose tip end abuts against said second piston, and a guide hole passing through said first piston and said first piston's shaft for guiding said pilot fluid pressure to a driving side pressure chamber of said second piston and,said second piston abuts against one end of said valve member and is operated by the operation force of the pilot fluid pressure introduced from said guide hole into a pressure chamber and by a pushing force of said first piston, thereby pushing said valve member.