High pressure enabled, low pressure activated automatic fluid control valve

摘要

A simple and highly reliable automatic valve is disclosed which is enabled by being subjected to a predetermined pressure and actuated as pressure is reduced from that pressure. A pressure differential of several orders of magnitude between enablement pressure and actuation pressure can be obtained by providing non-linear or plural springs which oppose fluid pressure against a reciprocable piston. The piston includes an aperture or passage which seals against a surrounding bore when the valve is closed. The piston is maintained in a position where the aperture or passage is sealed against the bore by a latch. The latch comprises a band spring held in position by a protrusion on the piston and released when the piston is moved by a predetermined fluid pressure. Fine adjustment of both enablement and actuation pressures is provided.