Patent ID: 6463959
Filing Date: 2002-10-15
Classification: F16D,F16H,G05D,Y10T

Abstract:
A pressure control valve, comprising:a housing with a supply-pressure port adapted to receive a supply pressure from a pressure source, a pilot-pressure port adapted to receive a pilot pressure from a pilot-pressure control device, a working-pressure port adapted to provide a working pressure to a pressure-actuated apparatus, and a drain port; a working-pressure chamber connected to the working-pressure port and, by way of a throttle passage, to the supply-pressure port; a pilot-pressure chamber connected to the pilot pressure port; a control piston having a first piston element, a second piston element, and a shaft connecting the first and second piston elements; an additional piston; a force-coupler device connecting the additional piston to the control piston; a biasing spring, wherein the additional piston is elastically biased into a rest position by the biasing spring; wherein the working-pressure chamber is confined between the first and second piston elements and the pilot-pressure chamber is confined between the second piston element and the additional piston, so that at a constantly supply pressure, the working pressure will vary as a function of the pilot pressure; wherein further the additional piston takes a position dependent on a difference between the working pressure and the pilot pressure; and the force-coupler device applies to the control piston a force whose magnitude depends on said position of the additional piston; wherein the additional piston will overcome the elastic bias and leave the rest position only when the working pressure exceeds the pilot pressure by a predetermined amount; and wherein the force-coupler device comprises a coupler spring interposed between and acting against the additional spring and the control piston.