Patent ID: 6615599
Filing Date: 2003-09-09
Classification: F25B

Abstract:
A thermostatic expansion valve for use in an air conditioning system that includes a refrigerant compressor, a condenser in fluid communication with an outlet of the compressor, a receiver in fluid communication with an outlet of the condenser, and an evaporator in fluid communication with an outlet of the receiver and with an inlet of the compressor, wherein said thermostatic expansion valve is adapted to control a flow of refrigerant to the evaporator under conditions of normal refrigerant charge, and is adapted to control the flow of refrigerant to the evaporator and to the compressor under conditions of low refrigerant charge, said thermostatic expansion valve comprising:a valve body comprising a first end, a second end, and an interior wall defining a fluid chamber between said ends; a liquid refrigerant inlet defined within said valve body in fluid communication with said fluid chamber such that the refrigerant can flow from the receiver through said liquid refrigerant inlet and into said fluid chamber; a first liquid refrigerant outlet defined within said valve body in fluid communication with said fluid chamber such that the refrigerant can flow from said fluid chamber through said first liquid refrigerant outlet and to the evaporator during the conditions of normal and low refrigerant charge; a second liquid refrigerant outlet defined within said valve body in fluid communication with said fluid chamber such that the refrigerant can flow from said fluid chamber through said second liquid refrigerant outlet and to the compressor during the conditions of low refrigerant charge; a needle disposed in said fluid chamber and being moveable therein to control the flow of the refrigerant into and out of said valve body during the conditions of normal and low refrigerant charge; and a notch defined within said needle extending between said liquid refrigerant inlet and said second liquid refrigerant outlet such that, during the conditions of low refrigerant charge, an amount of the refrigerant that flows into said fluid chamber, from the receiver can flow through said fluid chamber to said second liquid refrigerant outlet and to the compressor without flowing through the evaporator.