Piston rod with an integral piston for a shock absorber

Claim 1

In a cylinder piston device comprising a cylinder member having an axis and two end walls comprising a first end wall and a second end wall, a cavity being defined within said cylinder member between said two end walls; a piston rod axially movable with respect to said cylinder member and extending through said first end wall; a piston unit provided on said piston rod within said cavity, said piston unit separating said cavity into two working chambers comprising a first working chamber adjacent said first end wall and a second working chamber adjacent said second end wall, said first working chamber being an annular working chamber radially extending between a radially outer surface of said piston rod and a radially inner surface of said cylinder member; fluid passage means extending between said first and said second working chambers across said piston unit; the improvement comprising said piston rod and said piston unit being integrally formed by a piston rod tube; said piston rod tube comprising a first section close to said second end wall of said cylinder member, having a maximum outside diameter along at least part of its axial length and carrying at least one guiding ring engaging said radially inner surface of said cylinder member; said piston rod tube further comprising a second section adjacent said first section towards the first end wall of said cylinder member, said second section having a diameter smaller than said maximum diameter, a first shoulder axially directed towards said second end wall being established by the transition from said first section to said second section; said piston rod tube further comprising a third section adjacent said second section towards said first end wall of said cylinder member, said third section having a diameter smaller than said second section, a second shoulder axially directed towards said second end wall being established by the transition from said second section to said third section; a partition being axially supported by said second shoulder through an annular sealing member; a damping member being axially supported by said first shoulder; said damping member comprising at least one damping passage therethrough; said second section of said piston rod tube comprising at least one substantially radially directed bore at a location axially between said damping member and said partition, said damping member being preassembled together with said partition into a damping plate-partition unit, said damping plate-partition unit being housed within said piston rod tube, a central passage chamber being defined between said partition and said damping member, said central passage chamber being in fluid connection with said second working chamber by said at least one damping passage and being in fluid connection with said first working chamber by said substantially radially directed bore of said second section.