US Patent 7445096 Piston-cylinder unit and process for producing a piston-cylinder unit

A piston-cylinder unit, in particular gas spring, has a cylindrical pressure tube which has a surface protection on its outer surface. The piston-cylinder unit further has a piston, which is axially displaceable within the pressure tube and has a piston rod. The piston rod is led out of the pressure tube in a sealed manner through an end side opening at a piston-rod-exit end side of the pressure tube. To improve the corrosion prevention properties and the durability of the surface protection, an end region of the pressure tube which starts from the piston-rod-exit end side is excluded from the surface protection. A process for producing such a piston-cylinder unit is also disclosed.