To obtain an automatic control valve device capable of performing an excellent automatic control function as a differential pressure control valve keeping differential pressure constant before and after the valve and preventing clogging of a pilot valve unit with a perfect sealing function and being hardly causing a chattering and hunting irrespective of quick operation.
A main valve unit is provided with a main valve element integrated inside a main valve box and a main valve driving member having a pressure receiving area larger than that of the element. The element is positioned on the upstream side from a main valve seat, a throttling passage is formed between the element and main valve seat, the main valve driving member is slidably fitted on a cylindrical wall of the box, and a main valve driving pressure chamber is formed in the cylindrical wall. A pilot valve unit comprises a pilot A valve device and a pilot B valve device interlocked with each other. The pilot A and the pilot B valve devices opening and shutting in proportion to changes of differential pressure before and after the main valve unit are connected in series by means of a connecting passage between the upstream side and the downstream side from the main valve unit via the main valve driving pressure chamber midway. Accordingly, differential pressure before and after the main valve unit is maintained at a designated value.
KAWAMOTO MASAHIRO
MASASHIGE KOICHI
TAKAHASHI KENJI
