Patent ID: 7987681

Claim:
A flow control valve comprising: an enclosure having an inlet port and an outlet port for providing a fluid flow of a controlled fluid within a pathway extending therebetween; a sealed cavity formed by only a thermally conductive single flexible wall member and the enclosure, the cavity formed within the enclosure for carrying a controlling fluid therein, wherein one side of the flexible wall member is in contact with the controlling fluid and an opposing side of the flexible wall member is in contact with the controlled fluid during operation of the valve as the controlled fluid flows through the pathway, and wherein pressure within the sealed cavity is responsive to temperature of walls forming the sealed cavity; and an orifice in the pathway positioned immediately proximate the flexible wall member, wherein the wall member makes direct physical contact with an orifice entrance when the orifice is in a fully closed position, and wherein the flexible wall member is away from the orifice entrance when in an open position, thereby forming a metering orifice directly responsive to the position of the flexible wall member relative to the orifice entrance, and wherein a decrease in temperature of the controlled fluid in the pathway results in a decrease in temperature and pressure of the controlling fluid thereby causing the pressure in the sealed cavity to decrease when the controlled fluid becomes cooler, thus causing the flexible wall member to move farther away from the metering orifice and increase a rate of fluid flow therethrough, and further causing the pressure in the sealed cavity to increase when the controlled fluid becomes warmer, thus causing the flexible wall member to move closer to the metering orifice and decrease the rate of fluid flow therethrough, with a result that the rate of the flow of the metered controlled fluid is determined by the temperature of the controlled fluid relative to the pressure of the controlled fluid for controlling a subcooling of the controlled fluid at the inlet port.