CONTROL VALVE FOR VAPORIZATION PRESSURE

PURPOSE:To obtain a stable performance of a control valve and to improve airtightness of the same with no need of highly accurate machining to a main throttle valve, by using a diaphragm valve as the main throttle valve, and forming a valve seat for a pilot valve at the central portion of the main throttle valve. CONSTITUTION:A diaphragm valve 2 having a valve seat 3 and a pressure equalizing port 4 is disposed in a valve body 1 which is connected to the outlet of an evaporator at its left end and to the inlet of a compressor at its right end. A valve cover 5 is screwed to the valve body 1, and a pilot valve 7 slidable together with a retainer 6 toward and away from the valve seat 3 is disposed at the central portion in the valve cover 5. The pilot valve 7 is urged by a spring 8 in a valve opening direction. Further, a diaphragm 9 for detecting the vaporization pressure is fixed to an upper portion of the valve cover 5 by means of a retaining member 11 which is provided with a pressure setting spring 13 and an adjust screw 15. With such an arrangement, if vaporization pressure is raised, it is transmitted to the diaphragm 9 via the port 4 and opens both of the pilot valve 7 and the diaphragm valve 2.