Noise Reduction in a Thermostatic Expansion Valve

Abstract

A thermostatic expansion valve assembly is provided for an air conditioning system. A thermostatic expansion valve includes a valve body having an evaporator inlet port, an evaporator outlet port, a suction line port, and a liquid inlet port. The thermostatic expansion valve controls a flow of refrigerant from the liquid line port to the evaporator inlet port. A liquid line conduit is coupled to the liquid inlet port. The liquid line conduit has at least a segment elevated above the liquid inlet port. The vapor within the liquid inlet conduit accumulates at an uppermost portion of the segment prior to a compressor startup. A substantial amount refrigerant liquid is maintained between the uppermost portion of the segment and the liquid inlet port prior to the compressor startup.

1 . A thermostatic expansion valve assembly for an air conditioning system, the assembly comprising:
 a thermostatic expansion valve including a valve body having an evaporator inlet port, an evaporator outlet port, a suction line port, and a liquid inlet port, the thermostatic expansion valve controlling a flow of refrigerant from the liquid line port to the evaporator inlet port; and   a liquid line conduit coupled to the liquid inlet port, the liquid line conduit having at least a segment elevated above the liquid inlet port, wherein vapor within the liquid inlet conduit accumulates at an uppermost portion of the segment prior to a compressor startup, and wherein a substantial amount of refrigerant liquid is maintained between the uppermost portion of the segment and the liquid inlet port prior to the compressor startup.   
   
   
       2 . The thermostatic expansion valve assembly of  claim 1  wherein the liquid line between the uppermost portion of the segment and the liquid inlet port forms a liquid trap. 
   
   
       3 . The thermostatic expansion valve assembly of  claim 1  wherein the liquid line conduit between the uppermost portion and the liquid inlet port is of a predetermined length which contains refrigerant liquid and provides a continuous stream of refrigerant liquid for a predetermined period of time after the compressor startup for reducing the noise generated following the compressor startup. 
   
   
       4 . The thermostatic expansion valve assembly of  claim 3  wherein the liquid line is of a predetermined diameter for maintaining the continuous flow of refrigerant liquid to the thermal expansion valve for the predetermined period of time following the compressor startup. 
   
   
       5 . The thermostatic expansion valve assembly of  claim 4  wherein a segment of the liquid line conduit between the liquid inlet port and the uppermost portion includes at least a predetermined internal volume for maintaining the continuous flow of refrigerant liquid to the thermal expansion valve for the predetermined period of time following the compressor startup. 
   
   
       6 . The thermostatic expansion valve assembly of  claim 5  wherein the predetermined internal volume is at least five ounces. 
   
   
       7 . The thermostatic expansion valve assembly of  claim 5  wherein the predetermined internal volume is at least three ounces. 
   
   
       8 . The thermostatic expansion valve assembly of  claim 5  wherein the predetermined internal volume is at least one ounce. 
   
   
       9 . The thermostatic expansion valve assembly of  claim 1  wherein the liquid line conduit increases in elevation to the uppermost portion for directing vapor formed in the liquid line conduit between the liquid inlet port and the uppermost portion to flow toward the uppermost portion. 
   
   
       10 . The thermostatic expansion valve assembly of  claim 1  wherein the liquid line conduit includes insulation for insulating at least a portion of the liquid line conduit for minimizing a heating of refrigerant liquid within the liquid line conduit during a compressor off-period. 
   
   
       11 . A vehicle air-conditioning system comprising:
 a compressor configured to pump refrigerant;   a condenser configured to receive the refrigerant from the compressor and removing heat from the refrigerant;   an evaporator configured to receive the refrigerant, the evaporator being exposed to ambient air for removing the heat from the ambient air;   a thermostatic expansion valve including an evaporator inlet port, an evaporator outlet port, a suction line port, and a liquid inlet port; and   a liquid line conduit coupled between the condenser and the liquid inlet port, the liquid line conduit having at least a segment elevated above the liquid inlet port, wherein vapor within the liquid line conduit accumulates at the elevated segment during a compressor off-period.   
   
   
       12 . The vehicle air-conditioning system of  claim 11  wherein the liquid line includes a liquid trap. 
   
   
       13 . The vehicle air-conditioning system of  claim 11  wherein a substantial amount of the refrigerant is maintained as a liquid between an uppermost portion of the elevated segment and the liquid inlet port prior to compressor startup. 
   
   
       14 . The vehicle air-conditioning system of  claim 11  wherein the liquid line conduit is of a predetermined length from the liquid inlet port and the uppermost portion for maintaining a continuous flow of the liquid refrigerant to the thermal expansion valve for a predetermined period of time following the compressor startup. 
   
   
       15 . The vehicle air-conditioning system of  claim 14  wherein the liquid line conduit is of a predetermined diameter for maintaining the continuous flow of the liquid refrigerant to the thermal expansion valve for the predetermined period of time following the compressor startup. 
   
   
       16 . The vehicle air-conditioning system of  claim 11  wherein the portion of the liquid line conduit between the liquid line port and the uppermost portion includes at least a predetermined internal volume of the refrigerant for maintaining a continuous flow of the liquid refrigerant to the thermal expansion valve for the predetermined period of time following the compressor startup. 
   
   
       17 . The vehicle air-conditioning system of  claim 11  wherein the liquid line conduit includes insulation for insulating at least a portion of the liquid line conduit for minimizing a heating of refrigerant fluid within the liquid line conduit. 
   
   
       18 . The vehicle air-conditioning system of  claim 11  wherein the liquid line is made of a predetermined material having a thermal conductivity lower than that of aluminum for substantially limiting the thermal absorption by the liquid line conduit. 
   
   
       19 . The vehicle air-conditioning system of  claim 11  wherein the liquid line conduit is configured to be routed in an area of the vehicle spaced from a vehicle heat generating source for limiting the thermal absorption by the liquid line conduit. 
   
   
       20 . The vehicle air-conditioning system of  claim 11  wherein the liquid line conduit is configured to be routed behind a thermal barrier for limiting the thermal absorption by the liquid line conduit.