JPS5714912A - Flow rate control device - Google Patents

Abstract

PURPOSE:To improve the response properties, to reduce the drift of temperature and to ensure an accurate control flow rate, by providing a small aperture to a load pressure detector and at the same time installing a pilot pressure control valve to secure a constant differential pressure before and after the aperture. CONSTITUTION:A small aperture 31 is provided in a load pressure detector 12, and a pilot pressure control valve 40 which is energized in the closing direction by a spring is put into a path between a spring chamber 33 and a fluid tank to secure a constant differential pressure across the iris 31. At the same time, the pilot lines at the side of the spring 41 and its opposite side of the valve 40 are connected to the load side of the aperture 31 and the side of the chamber 33 respectively. As a result, the current flowing to the aperture 31, i.e. the detector 12 and a path 2d can be reduced down to a small constant level. Thus the degree of mixture both to the drift of temperature and the control flow rate can be suppressed although the detector 12 or the path 2d is thin and long.