Combined electrical cut-off and relief valve

Abstract

A combined over pressure relief and low fluid pressure electrical cut-off valve assembly having a housing defining a chamber with an inlet in communication with the high pressure gas of an air conditioning compressor and an outlet exposed to atmospheric pressure. A pressure sensitive snap-acting metal flexible diaphragm, having a central valve opening, extends across the chamber upper open end. An axial shaft, positioned in the valve opening, includes seal means on the underside of its head portion normally seated on the upper surface of the diaphragm to close the valve opening. A retainer is threaded on the shaft lower end and adjustably maintains an inner high pressure set point spring on the underside of the diaphragm. An outer spring retainer has an externally threaded shank mounted in the housing central bore and adjustably maintains an outer low pressure set point spring on the underside of the diaphragm. A contact ring is supported in the housing outlet whereby the diaphragm is held in electrically conductive relation with the ring by the outer spring such that the diaphragm is prestressed to flex downwardly away from the contact ring but not from the shaft head seal means in response to atmospheric pressure to open the contact without opening the valve opening.