Hydro-pneumatic damping device

Claim 1

A hydro-pneumatic damping device comprising (a) an inner cylinder having an axis and two ends, (b) a central cavity defined within said inner cylinder between said two ends, (c) an outer container surrounding said inner cylinder, said outer container having two ends adjacent respective ends of said inner cylinder, (d) an annular cavity defined between said inner cylinder and said outer container, (e) first and second closure means closing said two ends of said cylinder and said container, (f) piston rod passage means through the first ones of said closure means, (g) fluid passage means between said central cavity and said annular cavity adjacent the second ones of said closure means, (h) first fluid throttling means associated to said fluid passage means, (i) a piston rod axially extending through said piston rod passage means and into said central cavity, (k) a piston unit mounted on said piston rod within said central cavity and defining two working chambers within said cavity, a first working chamber adjacent said first closure means and a second working chamber adjacent said second closure means, (l) fluid connecting means connecting said two working chambers across said piston unit, (m) second fluid throtteling means associated to said fluid connecting means, (n) a body of liquid at least within the central one of said cavities, (o) a body of gas within said annular cavity, said first closure means comprising (aa) a cylinder closing unit surrounding said piston rod and having an inner end adjacent said first working chamber and an outer end, (bb) a sealing unit engaging said piston rod and having an inner end adjacent said outer end of said cylinder closing unit, (cc) venting passage means between said first working chamber and said annular cavity extending across said cylinder closing unit and axially inside said inner end of said sealing unit, (dd) check valve means associated to said venting passage means permitting fluid to flow from said first working chamber toward said annular cavity and preventing reverse flow, said check valve means comprising an annular check valve member in frictional sliding engagement with said piston rod for axial movement with said piston rod toward a sealing position during inward movement of said piston rod and toward an opening position during outward movement of said piston rod, first and second abutment means being provided for defining said sealing position and said opening position of said annular check valve member respectively.