Oscillation damper

An oscillation damper comprising a cylinder unit having an axis and a piston-piston rod unit axially movable with respect to said cylinder unit, fluid chambers being confined by said cylinder unit and said piston-piston rod unit within cavity means of said cylinder unit, said fluid chambers containing a damping fluid, fluid passage means for permitting a throttled fluid flow between at least some of said fluid chambers in response to axial movement of said piston-piston rod unit with respect to said cylinder unit, said throttled fluid flow providing a damping effect resisting said axial movement, said fluid passage means comprising cross-sectional area variation means within at least one fluid path, said cross-sectional area variation means being controlled by at least one EM-valve unit (electromagnetically operated valve unit), said EM-valve unit having biasing means for biasing said EM-valve unit toward an emergency condition and EM-transferring means (electromagnetic transferring means) for transferring said EM-valve unit from said emergency condition to a plurality of operational conditions against the action of said biasing means, said biasing means having a non-linear characteristic and exerting a weaker resistance to a change of said E-M valve unit from said emergency condition to a first operational condition and a stronger resistance to a change of said E-M valve unit from said first operational condition to at least one further operational condition and the rate of change of the increase in said resistance during the change from said emergency condition to said first operational condition being less than the rate of change of the increase of said resistance during the change from said first operational condition to said at least one further operational condition.

An oscillation damper comprising a cylinder unit having an axis and a piston-piston rod unit axially movable with respect to said cylinder unit, fluid chambers being confined by said cylinder unit and said piston-piston rod unit within cavity means of said cylinder unit, said fluid chambers containing a damping fluid, fluid passage means for permitting a throttled fluid flow between at least some of said fluid chambers in response to axial movement of said piston-piston rod unit with respect to said cylinder unit, said throttled fluid flow providing a damping effect resisting said axial movement, said fluid passage means comprising cross-sectional area variation means within at least one fluid path, said cross-sectional area variation means being controlled by at least one EM-valve unit (electromagnetically operated valve unit), allocated to an EM-valve path of variable flow resistance, said flow resistance of said EM-valve path being dependent on the position of one single valve member unit, said valve member unit being biased by biasing means toward an emergency position and being movable by EM-transferring means (electro-magnetic transferring means) from said emergency position to a first operational position and beyond said first operational position to at least one further operational position, said biasing means comprising first spring means biasing said valve member unit toward said emergency position and second spring means acting in the same direction-as said first spring means but being effective only after said valve member unit has been transferred toward said first operational position, such that said biasing means has a non-linear characteristic in response to a movement of said valve member unit with the rate of increase of the biasing force during a transition from said first operational position to said at least one further operational position being greater than the rate of increase of the biasing force during a transition from said emergency position to said first operational position.