JPS6218363B

A vacuum actuator having a vacuum chamber and an atmospheric chamber separated from each other by a diaphragm, and an actuator rod connected at one end to the diaphragm and extending across the atmospheric chamber to the outside of the actuator so as to be connected to an object to be actuated. At least one annular solenoid coil is mounted on the upper surface of the upper wall of the case defining the vacuum chamber, with the axis of the solenoid coil extending substantially at a right angle to the axis of the actuator rod. A plunger of the annular solenoid coil is adapted to be moved in one and the other directions along the axis of the annular solenoid coil. The end of the plunger is adapted to be moved into and out of a control pressure chamber of valve case. A port for introducing a vacuum from a vacuum passage into the control pressure chamber and a port for introducing the atmospheric pressure into the same are formed in the valve case coaxially with each other. A valve member disposed between these ports and displaceable by the plunger selectively opens and closes these ports. The pressurized fluid in the control pressure chamber is introduced into the vacuum chamber through a passage interconnecting the control pressure chamber and the vacuum chamber, to thereby produce a force which acts on the diaphragm.