Patent ID: 8157184
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 main 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, wherein the driving member is composed of a rotor case fixed around an opening of the valve housing opposite to the first port to form a cylindrical rotor chamber, a rotor having a rotor shaft in the axial direction of the rotor chamber and the main valve chamber and rotatably and movably disposed in the rotor chamber in the axis direction, and a stator coil attached to an outer circumference of the rotor case and driving the rotor, and the valve body is disposed at the rotor shaft near the valve seat, said driving member further including a supporting member fixed to the opening of the valve housing for separating the main valve chamber from the rotor chamber and for supporting the rotor shaft of the rotor, and configured to control an opening of the valve port by moving the rotor and the rotor shaft in the axial direction with a screw mechanism of the supporting member and the rotor shaft using a rotation of the rotor, and configured to equalize the pressure between the main valve chamber and the rotor chamber when the rotor is moved in the axial direction using a pressure equalizing path communicating with the main valve chamber and the rotor chamber, wherein the supporting member includes: a fitting part for fitting into the opening of the valve housing; and a flange part fixed to an end around the circumference of the opening of the valve housing, wherein a communicating path opening at the rotor chamber side is formed on the flange, and an outer diameter of the fitting part is a specific amount smaller than an inner diameter of an inner circumference of the valve housing, wherein a concave part concaved in a radial direction perpendicular to the axial direction is formed on the fitting part at the flange side, and a gap between the outer circumference of the fitting part and the inner circumference of the valve housing communicates with the communicating path via the concave part, and wherein the pressure equalizing path is composed of the gap between the outer circumference of the fitting part and the inner circumference of the valve housing and the communicating path.