To provide a compact and lightweight valve driving device, for which no restriction on an installation position and no installation of a carriage is required, by using compressed air or instrument air at a comparatively low pressure as power.
In a valve driving device, in which a hydraulic type operation machine 2 is actuated when hydraulic oil whose pressure is increased by feeding instrument air and the like into a booster 1 is fed out, a large diameter piston 18 is inserted into a cylinder 17 in the booster 1, and a small diameter cylindrical column part 19 concentrically arranged on one side of the piston 18 penetrates a separation wall 22 sealingly so as to be protruded to the adjacent second cylinder chamber 21. When the hydraulic oil is filled on one side 25 of the first cylinder chamber 20 while instrument air and the like is fed into the other side 26 in the cylinder chamber 20, the hydraulic oil, whose pressure is increased in inverse proportion to the operation area ratio between the air and the oil working on the piston 18, is fed out, while the hydraulic oil is sucked into one side 25 when instrument air and the like is fed into the second cylinder chamber 21.
SATO KOJI
FUKUNAGA AKIO
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