Expansion valve

Abstract

An expansion valve is configured such that a shaft, a first valve, a second valve, a compression coil spring, and an adjustment screw are coaxially arranged within a body exactly below a power element, and the first valve and the second valve control the flow rate in an interlocked manner. A second valve seat of the second valve is press-fitted into the body, and an amount of press-fitting of the second valve seat into the body is adjusted such that when the first valve is in a closed state in which a first valve element is seated on a first valve seat, the second valve is in a closed state in which a second valve element is seated on the second valve seat.

1 . An expansion valve comprising a first valve having a first valve element and a first valve seat, a second valve having a second valve element and a second valve seat, and a power element configured to control lifts of the first valve element and the second valve element in an interlocked manner,
 wherein the second valve seat of the second valve is a movable valve seat which is adjustable in a direction toward or away from the second valve element.   
     
     
         2 . The expansion valve according to  claim 1 , wherein the power element, the first valve, the second valve, and a spring which urges the first valve element and the second valve element toward the power element are coaxially arranged,
 wherein a high pressure inlet port for introducing high-pressure liquid refrigerant is communicated with a flow passage between the first valve and the second valve,   wherein a first low-pressure outlet port for delivering low-pressure vapor refrigerant is communicated with a downstream side of the first valve,   wherein a second low-pressure outlet port for delivering low-pressure vapor refrigerant is communicated with a downstream side of the second valve,   wherein the second valve seat is press-fitted into a body forming the first valve seat, and   wherein an amount of press-fitting of the second valve seat is adjusted such that the first valve and the second valve are simultaneously closed.   
     
     
         3 . The expansion valve according to  claim 2 , wherein the first valve element is axially movably disposed in a valve chamber into which high-pressure liquid refrigerant is introduced, such that a front end of a shaft for transmitting a driving force of the power element is in contact therewith through a first valve hole of the first valve seat, and that an axially extending portion of the second valve element is contact therewith through a second valve hole of the second valve seat. 
     
     
         4 . The expansion valve according to  claim 3 , wherein guides which slide along an inner wall of the valve chamber are integrally formed on respective portions of the first valve element toward the first valve seat and the second valve seat, and the guides have respective communication passages formed therethrough for introducing liquid refrigerant into the first valve hole and the second valve hole. 
     
     
         5 . The expansion valve according to  claim 4 , wherein the first valve element is configured such that a ratio between an axial length of a guide toward the first valve seat and an axial length of a guide toward the second valve seat is made equal to a ratio between a flow rate of the second valve and a flow rate of the first valve. 
     
     
         6 . The expansion valve according to  claim 1 , wherein there are provided high-pressure-dependent characteristics that the expansion valve is operated in a valve-closing direction according to a balance between a port diameter of the first valve through which high-pressure liquid refrigerant acts in the valve-closing direction, and a port diameter of the second valve through which high-pressure liquid refrigerant acts in a valve-opening direction. 
     
     
         7 . The expansion valve according to  claim 1 , wherein a shaft which transmits a driving force of the power element to the first valve, the first valve, and a first spring which urges the first valve element toward the shaft are coaxially arranged,
 wherein the second valve is disposed in a direction orthogonal to the axial direction of the shaft,   wherein a valve shaft of the second valve element is brought into contact with a tapered surface having a frustoconical shape and formed on an intermediate portion of the shaft, by an urging force of a second spring, to thereby cause a lift of the second valve element to be interlocked with a lift of the first valve element,   wherein a high pressure inlet port for introducing high-pressure liquid refrigerant is communicated with a flow passage between the first valve and the second valve,   wherein a first low-pressure outlet port for delivering low-pressure vapor refrigerant is communicated with a downstream side of the first valve,   wherein a second low-pressure outlet port for delivering low-pressure vapor refrigerant is communicated with a downstream side of the second valve,   wherein the second valve seat is screwed into a body forming the first valve seat, and   wherein a screwing amount of the second valve seat is adjusted such that the first valve and the second valve are simultaneously closed.   
     
     
         8 . The expansion valve according to  claim 7 , wherein the first valve element is brought into contact with or is welded to a front end of the shaft extended through a first valve hole of the first valve seat. 
     
     
         9 . The expansion valve according to  claim 7 , wherein there are provided high-pressure-dependent characteristics that the expansion valve is operated in the valve-closing direction according to a balance between a port diameter of the first valve through which high-pressure liquid refrigerant acts in the valve-opening direction, and a sealing diameter of an O ring disposed around the shaft at a location where the shaft is supported by the body, via which high-pressure liquid refrigerant acts on the shaft in the valve-closing direction. 
     
     
         10 . The expansion valve according to  claim 1 , further comprising a throttle passage member disposed on a downstream side of at least one of the first valve and the second valve, for preventing bubbles from being generated in refrigerant having passed through the first valve and the second valve.