Patent ID: 8157183
Filing Date: 2012-04-17
Classification: F25B,Y02B

Abstract:
1. An expansion valve for controlling a flow rate of a refrigerant in a first flow direction of the refrigerant and for discharging the refrigerant in a second flow direction, said expansion valve comprising: a valve housing having a first port communicating with a cylindrical main valve chamber and with a side part of the main valve chamber, and a second port communicating with an end of the main valve chamber in an axial direction thereof; a valve seat slidably disposed in the main valve chamber in the axial direction of the valve chamber, and having a sub valve chamber opposed to the second port in the main valve chamber, a valve port for connecting the sub valve chamber to the second port, and a connecting hole for always connecting the sub valve chamber to the first port; a valve plug for opening and closing the valve port of the valve seat by moving relative to the valve seat in the axial direction; and a driving member for driving the valve plug in the axial direction, wherein in a case that the first port is under high refrigerant pressure and the second port is under low refrigerant pressure, a flow rate of the refrigerant flowing from the sub valve chamber through a path between the valve plug and the valve port is controlled by closing the second port with the valve seat seated around the second port due to differential pressure between the first and second ports and by controlling a position of the valve plug in the axial direction with the driving member, and wherein in a case that the first port is under low refrigerant pressure and the second port is under high refrigerant pressure by making the refrigerant flow reversely, the refrigerant is discharged to the first port via the second port and the main valve chamber, said second port is opened by moving the valve plug in the axial direction with the driving member and by separating the valve seat from the second port due to the differential pressure between the second and first ports.