Cylinder-piston device

In a gas spring device, comprising:

• a cylinder having an axis and two end walls;
• a cavity defined within said cylinder;
• an axially movable piston rod extending inward and outward of said cavity through an aperture in at least one of said end walls;
• a piston unit within said cavity and operatively connected to said piston rod, said piston unit defining first and second working chambers within said cavity and including a piston member, said piston member having two axially directed end faces, namely a first end face adjacent said second working chamber, each of said end faces lying in a plane substantially perpendicular to the axis of said cylinder and being substantially covered by a first and a second cover plate, respectively;
• a fluid within said cavity;
• at least one fluid path interconnecting said first and said second working chambers;
• said fluid path comprising a first portion having a first end and a second end, a second portion having a first end and a second end and a third portion;
• said first portion comprising a first meander-shaped sequence of passage sections extending in a substantially circumferential direction around said axis of said cylinder and provided between said first end face and said first cover plate, said first end of said first portion being open to said first working chamber;
• said second portion comprising a second meander-shaped sequence of passage sections extending in a substantially circumferential direction around said axis of said cylinder, and in a plane substantially transverse to said axis, and provided between said second end face and said second cover plate, said first end of said second portion being open to said second working chamber;
• said third portion comprising a substantially axially directed bore through said piston member and interconnecting said second end of said first portion and said second end of said second portion,
• said cylinder-piston device further comprising an additional passage means connecting said first and second working chambers, and wherein said piston member and one of said cover plates comprises an annular groove receiving a piston ring which is axially movable within said annular groove, said piston ring comprising a check valve varying the fluid cross section of said additional passage means in response to the direction of movement of said piston rod.

In a cylinder-piston device, comprising:

• a cylinder having an axis and two end walls;
• a cavity defined within said cylinder;
• an axially movable piston rod extending inward and outward of said cavity through an aperture in at least one of said end walls;
• a piston unit within said cavity and operatively connected to said piston rod, said piston unit defining first and second working chambers within said cavity and including a piston member;
• a fluid within said cavity;
• and
• at least one passage-defining means extending through said piston unit and connecting said first and second working chambers during at least part of the stroke of said piston unit with respect to said cylinder, the improvement in said piston unit wherein:
• said passage-defining means includes means defining a substantially meander-shaped sequence of passage sections extending over at least part of the length of said passage;
• said piston member has two axially directed end faces, each of said end faces lying in a plane substantially perpendicular to the axis of said cylinder;
• said meander-shaped sequence of passage sections being defined by corresponding first and second sequences of channel sections, extending in a substantially circumferential direction around said axis of said cylinder, provided in each axially directed end face of the piston member of said piston unit;
• said first and second sequence of channel sections each including means at one end thereof defining an opening to said first and second working chambers, respectively, said first sequence of channel sections and said second sequence of channel sections being connected by at least one axial bore at a location remote from said one end thereof, which at least one axial bore extends completely across the piston member of said piston unit;
• and
• first and second cover plates overlying each of said end faces and covering in a fluid-tight manner said respective first and second channel sections.