Patent ID: 6491059
Filing Date: 2002-12-10
Classification: F16K,Y10T

Abstract:
A smooth exhaust valve comprising:a first port to be connected to a vacuum chamber; a second port to be connected to a vacuum pump; 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 first port and said second port in parallel; a main valve body for opening and closing said main flow path; an auxiliary valve body for opening and closing said auxiliary flow path; a first piston connected to said main valve body through a first shaft; 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; an auxiliary pressure operating chamber for applying air pressure in a valve-opening direction to said second piston; first spring means for repulsing said main valve body in a valve-closing direction; second spring means for repulsing said auxiliary valve body in a valve-closing direction; and an adjusting rod mounted to a valve casing so as to be operated from outside to move forward and rearward and for changing a compressed amount of said second spring means by operation of forward and rearward movements of said adjusting rod to adjust a repulsing force of said second spring means.