Expansion valve

An expansion valve mounted to an air conditioner for controlling the flow of a refrigerant, the expansion valve comprising;

• a piping member including refrigerant passages to which pipes communicated with various equipment of the the air conditioner are connected, the refrigerant passages including an upstream refrigerant supply passage, a downstream refrigerant supply passage and a refrigerant return passage;
• a cassette unit inserted to the piping member, said cassette unit comprising a tube member formed integrally with a flange unit, a guide member disposed between the downstream refrigerant supply passage and the refrigerant return passage, an orifice member, and a plate member fixed to the inside of the tube member, a valve means disposed between the upstream and downstream refrigerant supply passages and equipped inside a valve chamber defined by said orifice member, a plate member further defining said valve chamber, a spring disposed between the plate member and the valve means for biasing the valve means toward the orifice member, a shaft member for driving the valve means, a lid member welded onto the flange portion, a diaphragm pinched between the lid member and the flange portion and defining a gas charge chamber, and a stopper member having at the center thereof a tubed portion filled with absorbent for transmitting the displacement of the diaphragm to the shaft member;
• a ring for fixing to the piping member the lid member of the cassette unit inserted to the piping member;
• and
• three seal members disposed between the outer wall of the cassette unit and the inner wall of the piping member, a first seal member disposed in a vicinity of the valve means to prevent refrigerant leakage between the upstream refrigerant supply passage and the downstream refrigerant supply passage, a second seal member disposed in a vicinity of the guide member to prevent refrigerant leakage between the downstream refrigerant supply passage and the refrigerant return passage and a third seal member to prevent leakage of refrigerant from the refrigerant return passage passed the flange unit and exteriorly of the valve.