| 摘要 |
A refrigerant flow-control device is automatically operable between a normal or low-flow condition and a pressure relief or high-flow condition in response to pressure drop across the flow-control device, in one embodiment the flow-control device includes a tubular-shaped body having an inlet, an outlet, and a refrigerant passageway extending from the inlet to the outlet, a cylindrically-shaped restrictor secured within the tube and forming a second restriction, and a cylindrically-shaped collar secured within the tube and forming a poppet-valve flow passage. The collar is spaced-apart from the restrictor within the tube. A poppet is located within the tube partially between the restrictor and the collar and carries a valve element. The poppet is movable between a first position closing the poppet-valve flow passage to generally prevent refrigerant flow therethrough and a second position opening the poppet-valve flow passage to permit refrigerant flow therethrough. The poppet forms a first restriction. The first restriction has a higher resistance to refrigerant flow than the second restriction. A compression spring is located within the tube between the poppet and the restrictor and resiliently urges the valve element into the first position. With the valve element in the first position, the flow-control device is in a low flow condition as refrigerant flow is controlled by the first restriction. At a predetermined blow-off pressure, fluid pressure overcomes the spring to automatically move the valve element to the second position. With the valve element in the second position, the flow-control valve is in the high-flow condition as refrigerant flow is controlled by the second restriction. Once the pressure spike is relieved, the spring returns the valve element to the first position so that expansion device is in the normal or low-flow condition.
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