Patent ID: 8573560

Claim:
A vacuum control valve connected between a vacuum chamber and a vacuum pump and configured to control the vacuum pressure in the vacuum chamber by manipulating valve opening using working fluid, the vacuum control valve comprising: a control valve main body comprising a flow passage and a valve seat formed in the flow passage, the flow passage connecting the vacuum chamber and the vacuum pump; an operation unit comprising a valve body, a piston, and a rod that joins the valve body and the piston, the valve body being configured to manipulate the valve opening by adjusting a lift that is a distance between the valve body and the valve seat and to block the flow passage by contacting the valve seat; a cylinder configured to house the piston, a first side of the cylinder being connected to the control valve main body; a head cover attached to the cylinder so as to cover an edge portion of the cylinder on a second side of the cylinder opposite to the first side; a biasing unit configured to press the operation unit in a direction for reducing the lift; and a bellofram configured to seal a gap between an outer peripheral surface of the piston and an inner peripheral surface of the cylinder following a movement of the piston, wherein the operation unit and the cylinder include: a valve opening manipulation chamber sealed by the bellofram, the valve opening manipulation chamber having a tubular shape surrounding the rod and being configured to generate a load applied to the piston in a direction for increasing the lift in accordance with a pressure exerted by the working fluid; and a shutoff load generation chamber formed inside the rod, the shutoff load generation chamber having a common axial center line with the valve opening manipulation chamber and being configured to generate a load applied to the operation unit in a direction for reducing the lift in accordance with a supply of the working fluid, the vacuum control valve further comprising: a sliding convex portion provided on the head cover and slidably accommodated in the shutoff load generation chamber, the sliding convex portion guiding a movement of the rod by sliding along an inner peripheral surface of the shutoff load generation chamber; a sealing unit provided to seal between the shutoff load generation chamber and the sliding convex portion; and a flow passage configured to supply the working fluid to the shutoff load generation chamber.