Patent ID: 8100387
Filing Date: 2012-01-24
Classification: F16F

Abstract:
1. A combined oil/pneumatic spring, comprising: a first hollow casing; a first piston adapted to slidably move in a substantially fluid-tight manner within said first hollow casing; a rod connected rigidly with an extremity thereof to a central portion of said first piston such that a portion of said rod protrudes outside of said first hollow casing; a first chamber provided in an interior of said first hollow casing, said first chamber being delimited by said first piston and, partially, surfaces of said rod and inner walls of said first hollow casing; a second chamber provided in the interior of said first hollow casing, said second chamber being a sealed chamber delimited by said first piston and inner walls of said first hollow casing on an opposite side of said first piston relative to said first chamber; a mass of hydraulic medium filling up said second chamber; a second hollow casing; a second piston adapted to slide within said second hollow casing and fluid-tightly fitting against walls of the second hollow casing so as to define a third chamber and a fourth chamber, said third chamber being a variable-volume chamber which is constantly filled up with a hydraulic medium, said fourth chamber being a variable-volume chamber which is constantly filled up with gas, wherein said third and fourth chambers are distinct and separated from each other by said second piston; a first conduit connecting an interior of said second chamber with an interior of said third chamber; first valve means associated to said first conduit and adapted to selectively open and close said first conduit; an expansion vessel; a second conduit connecting said expansion vessel with said first conduit at a position lying upstream of said first valve means; second valve means provided on said second conduit, said second valve means being selectively controllable so as to allow hydraulic medium to flow through said second valve means in both directions; and control means adapted to selectively control opening and closing of said first valve means and said second valve means.