Patent ID: 6494229
Filing Date: 2002-12-17
Classification: F16K,Y10T

Abstract:
A pilot-type two-port vacuum valve comprising:a chamber port to be connected to a vacuum chamber and a pump port to be connected to a vacuum pump; a casing including said ports; a main flow path having a large cross-sectional area and an auxiliary flow path having a smaller cross-sectional area than said main flow path for connecting said chamber port and said pump port in parallel; a main valve body for opening and closing a main valve seat in said main flow path and an auxiliary valve body for opening and closing an auxiliary valve seat in said auxiliary flow path; a first piston connected to said main valve body through a first shaft and a second piston connected to said auxiliary valve body through a second shaft; a main pressure operating chamber for applying air pressure in a valve-opening direction to said first piston and an auxiliary pressure operating chamber for applying air pressure in a valve-opening direction to said second piston; and first spring means for repulsing said main valve body in a valve-closing direction and second spring means for repulsing said auxiliary valve body in a valve-closing direction, wherein said main valve body includes a valve sealing member for coming in contact with and separating from said main valve seat to thereby open and close said main valve seat in a poppet manner and a pillar-shaped flow rate adjusting portion to be fitted in an inner hole of said main valve seat to move in said inner hole by opening and closing of said valve sealing member and said flow rate adjusting portion is formed in a gradually-tapered shape to thereby have a function of gradually increasing a flow rate of air flowing through said main flow path in opening of said valve sealing member.