Patent ID: 6814338
Filing Date: 2004-11-09
Classification: F16K,Y10T

Abstract:
A two-port vacuum valve capable of adjusting valve-opening comprising:a valve housing having a first main port, a second main port and a main flow passage which connects both said main ports with each other, a main valve member provided in said valve housing for opening and closing said main flow passage, a cylinder connected to said valve housing, a first piston and a second piston accommodated in a piston chamber of said cylinder such that these pistons can independently slide and abut against each other, a first pressure chamber formed between said first piston and a first end wall on the side of one end of said cylinder, and a second pressure chamber formed between said second piston and a second end wall on the side of the other end of said cylinder, a first operation port and a second operation port for respectively supplying pressure fluid to said first pressure chamber and said second pressure chamber, a first rod slidably passing through a first end wall of said cylinder and connecting said first piston and said main valve member with each other, a second rod slidably passing through a second end wall of said cylinder and having one end connected to said second piston and the other end extending outside of said cylinder, a positioning mechanism which comprises a stopper mounted to said second rod such that its position can be adjusted and an abutting portion against which said stopper abuts and stops, and which defines a forward movement position of said second piston, and a return spring for biasing said main valve member in its closing direction.