Image Number 3 for United States Patent #4485899.
In a shock absorber unit for vehicles of the double-tube type a piston rod guiding and sealing unit is provided adjacent a first end of a cylinder and a container surrounding the cylinder, and a bottom valve unit is provided at a second end of the cylinder and the container, respectively. The cavity within the cylinder is divided into two working chambers by a piston unit. The piston unit is connected to a piston rod extending through the piston rod guiding and sealing unit. The cavity within the cylinder is filled with a damping liquid. The compensation chamber defined radially between the cylinder and the container is partially filled with damping liquid and partially filled with gas. Adjacent the piston rod guiding and sealing unit, there is provided a by-pass connection the working chamber adjacent the piston rod guiding and sealing unit and the compensation chamber. This by-pass defines a throttling flow cross-sectional area. This flow cross-sectional area is defined by a temperature sensitive member having a high coefficient of thermal expansion, such that the throttling flow cross-sectional area is reduced in response to increasing temperature. By this reduction the reduction of viscosity is compensated for, such as to maintain the damping characteristic of the shock absorber unit approximately invariable within a predetermined range of operational temperatures.