Patent ID: 7806244

Claim:
A piston/cylinder unit comprising: a closed cylinder filled with a fluid under pressure; a piston dividing the cylinder into a first working space and a second working space, the piston being connected to a piston rod extending through the second working chamber; a passage through the piston connecting the first working chamber to the second working chamber; a valve closing member movable between an open position and a closed position wherein said member closes said passage; a solenoid comprising a coil, a coil core, and an armature in said piston, said armature driving said valve closing member between said closed position and said open position in response to a magnetic field produced by a current applied to said coil, said cylinder forming a magnetic field guide tube, wherein the coil core extends out of the coil to an end opposite from said armature, the unit further comprising a steel disc surrounding the coil core between the coil and the end, the disc extending radially to a point close to the cylinder.