Patent ID: 7117886

Claim:
A vacuum regulating valve comprising: a valve main body section including a valve housing including a first and a second main port that to be connected to a vacuum chamber and a vacuum pump, a flowchannel connecting between the first and second main ports, and a valve seat provided in such a manner as to surround a peripheral portion of the first main port; a valving member that opens and closes the valve seat provided in the valve housing; a valve shaft that extends from the valving member along the direction of an axial line of the valve housing to an extent that an end of the valve shaft reaches a cylinder section; and a return spring that urges the valving member along a direction of closing the valve seat; the cylinder section including a piston mounted to the end of the valve shaft; a pressure receiving chamber that causes a fluid pressure in a direction of opening the valving member to act on the piston; and a pilot port that discharges a pilot fluid to the pressure receiving chamber; a valve-opening regulating section including a stopper that protrudes to a back surface of the piston to define a movement range of the piston; and an electric motor that performs stepless forward-backward driving of a mover provided to the stopper to an arbitrary position through a rotation-linear motion converter mechanism; and a valve control section including a rotation angle sensor that detects a rotation angle of the electric motor; a pressure sensor that detects a pressure in the vacuum chamber; a solenoid valve that supplies and discharges the pilot fluid to the pilot port; a main controller that, in accordance with a signal indicative of a pressure set value and a pressure signal from the pressure sensor, outputs a signal indicative of a stopper position for appropriately setting the opening of the valving member to a motor controller which controls driving of the electric motor, and outputs a control signal being used to control a fluid pressure in the pressure receiving chamber to be a pressure necessary for the solenoid valve; and the motor controller that controls the electric motor in accordance with the signal indicative of the stopper position from the main controller and a signal from the rotation angle sensor, wherein the opening of the valving member is controlled with the piston in a manner that the stopper is displaced by the electric motor.