PURPOSE: To dispense with the external power such as a motor and a compressor by making use of an auxiliary pump provided with an high vacuum exhauster itself to open/close a main valve, to reduce the cost of the whole exhaust system, and to save the space.
CONSTITUTION: When a three-way cock 7 is opened, the pressure difference is generated between an evacuated tank 11 and a cylinder 4, and a valve disk is pushed upward by the atmospheric pressure to open a main valve 3. The tank 11 is evacuated through an orifice 10 having the conductance of 0.02 to 1% of the exhaust speed of an auxiliary pump to reduce the reduction of the degree of vacuum during the back pressure evacuation of a main exhaust pump 2. When the three-way valve 7 is closed, the air leak is made in the cylinder 4 to realize the pressure balance, and the valve disk 15 is pushed down by an elastic body to close the main valve 3.
ITO MASUHIRO
OZASA SUSUMU
HITACHI SCIENCE SYSTEMS LTD
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