Patent ID: 7073642

Claim:
A gas spring, comprising a cylindrical casing ( 1 ) which has an inside wall ( 20 ), a central longitudinal axis ( 5 ), a bottom ( 2 ) and an end ( 4 ) opposite the bottom ( 2 ); a piston rod ( 6 ) which is concentric of the central longitudinal axis ( 5 ) and which is extended from the end ( 4 ) through a guide and seal unit ( 8 ) and out of the casing ( 1 ) ; a damping piston ( 9 ) which is disposed on an end, inside the casing ( 1 ), of the piston rod ( 6 ), dividing the casing ( 1 ) into two sectional casing chambers ( 10 , 11 ); a filling of compressed gas inside the casing ( 1 ); a damping device ( 28 a ) for velocity-dependent damping of a motion of stroke of the damping piston ( 9 ), said velocity-dependent damping device ( 28 a ) comprising at least one piston member ( 12 , 16 ) which is tightly mounted on the piston rod ( 6 ), an annular piston ( 23 ) which is displaceable in the direction of the axis ( 5 ) relative to the at least one piston member ( 12 , 16 ), and at least one elastic valve disk ( 25 , 26 ) which is disposed between the at least one piston member ( 12 , 16 ) and the annular piston ( 23 ) and which bears sealingly against the at least one piston member ( 12 , 16 ) when a given limit of stroke velocity is exceeded; and another damping device ( 45 ) for path-dependent damping of a motion of stroke of the damping piston ( 9 ), said path-dependent damping device ( 45 ) comprising a damping fluid passage with a path-dependently varying cross section between the two sectional casing chambers ( 10 , 11 ), said damping fluid passage being a longitudinal groove ( 45 ) on the inside wall ( 20 ) of the casing ( 1 ), said longitudinal groove ( 45 ) substantially extending between a position of maximum insertion and a position of maximum extension of the damping piston ( 9 ) and comprising at least a first groove area ( 48 ) having a varying cross section and being allocated to the position of maximum insertion, a second groove area ( 49 ) having a constant cross section and adjoining to the first groove area ( 48 ), a third groove area ( 50 ) having a varying cross section and adjoining to the second groove area ( 49 ), and a fourth groove area ( 51 ) having a constant cross section and adjoining the third groove area ( 50 ).