Patent ID: 7048100
Filing Date: 2006-05-23
Classification: E05C,F16F

Abstract:
1. A piston/cylinder unit, comprising: a closed cylinder defining a cylinder interior; a piston axially displaceably guided in said closed cylinder and having an annular seal, said piston dividing said cylinder interior into first and second working spaces, each of said first and second working spaces being filled with hydraulic fluid; a piston rod connected to said piston, said piston rod extending through the cylinder interior and sealingly guided to the outside of the cylinder through a closing wall of said cylinder; a first nonreturn valve arranged in said piston and having a first closing element which is force-loaded in a closing direction toward a closed position, said first closing element being openable for connecting said first working space to said second working space when a pressure in said first working space exceeds a first opening pressure; and a second nonreturn valve arranged in said piston and having a second closing element which is force-loaded in a closing direction toward a closed position, said second closing element being openable for connecting said second working space to said first working space when a pressure in said second working space exceeds a second opening pressure, wherein a surface area of one of said first and second closing elements that is acted upon by a pressure in the respective one of said first and second working spaces increases when said one of said first and second closing elements moves along an opening stroke from the closed position toward an open position, and wherein said one of said first and second nonreturn valves comprises a stepped piston which is arranged displaceably in a corresponding stepped hole defined in said one of said first and second nonreturn valves, said stepped piston having steps with end-side surfaces which can be acted upon effectively by the pressure of the respective one of said first and second working space comprising a smallest step and a further step, only said smallest step being pressurized in the closed position, said further step being pressurized when said closing element is moved along said opening stroke away from said closed position, and at least one step of the steps in said stepped hole have a connection to a next-larger step of the steps in said stepped hole, said connection being openable when a position along the opening stroke is reached by said stepped piston.