Piston sealing control system

Claim 1

A control system for sealing a hydrostatically journaled working piston against the wall of a cylinder carrying said piston, said cylinder being closed at both ends by first and second cylinder covers, said working piston having a hydrostatically journaled piston rod attached to at least one of its end faces and extending through said second cylinder cover for supplying effective work, a first end space formed between one of said end faces of said working piston and said first cylinder cover, and a second end space formed between the other end face of said working piston and said second cylinder cover, said system comprising means communicating with said first end space for supplying fluid under pressure thereto so that said pressure acts on one end face of said working piston means communicating with said second end space for supplying fluid under pressure thereto so that said pressure acts on the other end face of said working piston, a first circumferential groove located on the circumferential surface of said working piston adjacent the end face thereof broadening said first end space, a second circumferential groove located on the circumferential surface of said working piston adjacent said second end space, a plurality of shallow bearing chambers about the circumferential surface of said working piston for hydrostatically journaling said working piston in said piston carrying cylinder, said chambers being located between said first and second circumferential grooves, first duct means communicating between each of said bearing chambers and said second end space, a cylindrical body secured within said piston being closed at one end thereof, first, second and third pistons within said body being spaced apart and axially movable therein, means connecting said first and second pistons and means connecting said second and third pistons said connecting means having diAmeters smaller than the diameters of said pistons, a first middle chamber being formed between the first and second pistons, a second middle chamber being formed between the second and third pistons, a first end chamber formed between the end face of said first piston and the closed end of said body and a second end chamber bound by the end face of said third piston, an aperture in the wall of said body communicating with said first middle chamber, second duct means communicating with said aperture and said second groove, an outlet port comprising a recess on the surface of said second piston communicating with said first middle chamber, an annular chamber formed between the circumferential surface of said second piston and the inner wall of said body in communication with said recess, said outlet port being adjustable in size by the relative position of said pistons within said body, third duct means in constant communication at one end thereof with said annular chamber regardless of the position of said pistons, said third duct means communicating at its other end thereof with a pressure which is less than the pressure acting on both end faces of said working cylinder, fourth duct means in said working piston communicating between said first groove and said first end chamber, fifth duct means communicating between said second end chamber and said second end space, the diameters of said first and third pistons being unequal so that the end surfaces thereof have the same ration of surface area as the corresponding end surfaces of said working piston so that the pressure exerted on both ends of said working piston is the same as the pressure exerted on corresponding ends of the piston assembly within said body.