Zf Friedrichshafen Ag

Thomas Meyer

Holger Kirchner

Hubert Beck

Norbert Ackermann

Process for producing a pressure vessel having an enveloping body which occupies an arch shape in its predetermined installation position. The enveloping body has pillow-shaped portions which are connected to one another by stamped transitions at the inner diameter area of the enveloping body. The enveloping body for the intended installation position is placed with its inner diameter area one-sidedly on a die having a raised wedge-shaped profile. A designated outer diameter area of the enveloping body contacts a supporting surface, and the enveloping body is filled with a pressure medium so that the enveloping body is tensioned on the die and, in so doing, is plastically deformed in the area of the wedge-shaped profile.

Process for producing a pressure vessel

A self-pumping hydropneumatic spring strut is provided to have internal level control. The spring strut has an outer tube having one end sealed by a piston rod guide, a working cylinder received inside the outer tube, and a hollow piston rod extending into the working cylinder through the piston rod guide. The piston rod carries a piston, which is operable to travel axially inside the working cylinder in a sealing manner and separates the working cylinder into first and second working spaces. The first working space is under a high-pressure from a high-pressure chamber and acting as a spring and the second working space is located on a piston rod-side. The spring strut also has a pump rod received inside the hollow piston rod. The pump rod and the hollow piston rod form a piston pump, which, in response to sprung movements acted thereonto, conveys a damping media from a low-pressure chamber into the first working space connected to the high-pressure chamber. The high-pressure chamber and the low-pressure chamber are each connected to the atmosphere by a filling connection formed in the piston rod guide and a check valve operable to selectively communicate the high-pressure or the low-pressure chamber to the atmosphere.

Self-pumping hydropneumatic spring strut

A self-pumping hydropneumatic spring strut with internal leveling control, particularly for motor vehicles, has an outer tube having an oil-filled high-pressure work space in the work cylinder, which high-pressure work space is under pressure by at least one gas cushion which is arranged in a high-pressure chamber and acts as a spring, a second work space on the piston rod side, and a piston which is supported by a hollow piston rod and which is axially displaceable in the work cylinder in a sealed manner, a piston pump which is driven by the spring movement of the vehicle and pumps oil out of a low-pressure chamber into the work space connected to the high-pressure chamber and which comprises a pump rod and a pump cylinder which is formed by the hollow piston rod, and the high-pressure chamber can be connected to the atmosphere by a flow connection which is arranged in the piston rod guide and has a closing element. The piston rod is sealed in the piston rod guide by means of at least two seals which are arranged one behind the other axially. A flow connection extends from between two adjacent seals into the low-pressure chamber. The flow connection is acted upon by a check valve which passes damping medium only in direction of the low-pressure chamber.

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Siegburg, Germany

Thomas Meyer