Thermostatic expansion valve and air conditioning system for low refrigerant charge

摘要

A thermostatic expansion valve (10) controls a flow of refrigerant. The valve (10) includes a body (46) defining a fluid chamber (44). A refrigerant inlet (54) is defined within the body (46). The inlet (54) communicates with the chamber (44) such that the refrigerant can flow through the inlet (54) and into the chamber (44). First and second outlets (56, 42) are defined within the body (46). The first outlet (56) communicates with the chamber (44) such that the refrigerant can flow from the chamber (44) to an evaporator (20) during normal and low refrigerant charge. The second outlet (42) communicates with the chamber (44) such that the refrigerant can flow from the chamber (44) to a compressor (14) during low charge. A moveable needle (62) controls the flow of the refrigerant into and out of the body (46). A notch (80) is defined within the needle (62) such that, during low charge, the refrigerant that flows into the chamber (44) can flow to the second outlet (42) and to the compressor (14) without flowing through the evaporator (20).