Expansion device

Abstract

To provide an expansion device which controls high pressure-side pressure such that the pressure does not exceed a predetermined pressure in terms of absolute pressure, while operating in response to differential pressure between pressure at an inlet thereof and pressure at an outlet thereof. An expansion device comprises an orifice for expanding refrigerant, a valve element disposed on a downstream side of a valve hole and urged by a shape-memory alloy spring in a valve-opening direction, a shaft disposed to extend through the valve hole and having one end thereof rigidly fixed to the valve element, and a spring provided at the other end of the shaft, for receiving load generated by differential pressure between pressure of refrigerant at an inlet of the device and pressure of refrigerant at an outlet thereof, in a valve-opening direction. The shape-memory alloy spring senses the temperature of refrigerant on the downstream side to perform temperature-dependent correction of a set value of the differential pressure for opening the valve element. Therefore, pressure on an upstream side of the valve hole is controlled as if by absolute pressure. Further, when the pressure on the upstream side exceeds a predetermined pressure, the spring is bent to open the expansion valve, and hence the pressure is prevented from rising above the predetermined pressure.

Dependencies are inferred from the claim text.