Firma Carl Freudenberg

Hermann Schilling

Ulrich Freudenberg

Eberhard Bock

Reinhard Stief

Heinz Seifert

Uwe Weltin

G&uuml;nter Hofmann

Markus Leibach

A method and tool for producing bipolar plates having liquid channels and gas channels, and having sealing elements made of polymer material for fuel cells. The bipolar plates are stamped, i.e., liquid and gas channels are impressed into the bipolar plates, and sealing elements are applied to the bipolar plates in one tool in two steps directly following each other.

Method and tool for producing bipolar plates

An active vibration damper for a reciprocating machine part, comprising an inertial mass that can be displaced in the direction of the reciprocating motion and a support plate that can be fastened to the machine part. The inertial mass and the support plate are connected to one another by a spring element. The natural frequency of the vibrating system constituted by the inertial mass and the spring element is at most as great as the frequency of the reciprocating motion. The inertial mass can be moved by plunger coil fastened to the support plate so as to be immobile with respect thereto, and the spring element can be deformed by the plunger coil. The inertial mass consists of a cup-shaped magnet that at least partly concentrically surrounds the plunger coil radially on the inside and outside. The cup-shaped magnet is guided by a guideway parallel to the axis of the plunger coil.

Active vibration damper

A vibration damper comprising a magnet having a mass m and an elasticity c.sub.1, and a spring element of flexibly compliant material having an elasticity c.sub.2, wherein the magnet is mounted on the spring element so that the resiliency c.sub.1 of the magnet and the resiliency c.sub.2 of the spring element form an combined elasticity c.sub.tot of the vibration damper. The vibration damper is attached to a plate of magnetizable material which exhibits an interference frequency .omega..sub.1 and is attracted to the magnet. The magnet is movable relative to said plate in every operating position. The mass m and elasticity c.sub.1 of the magnet and the elasticity c.sub.2 of the spring element are adjusted to achieve a natural frequency .omega..sub.0 on the basis of the formula: ##EQU1## so as to allow the resulting natural frequency .omega..sub.0 to be adjusted in accordance with the interference frequency .omega..sub.1 of the plate.

Vibration damper

A panel for sound insulation of vehicles or other devices is described which is constructed of a fabric of autogenously and chemically bonded, matted polyester fibers having fine surface pores. The fabric is shaped by compression so that it has a thickness of 1 to 3 mm. and exhibits an acoustical impedance of about 30 to about 100 Rayl.

Sound absorbing irregularly shaped panel

A silencer for reducing the noise of an exhausting gas stream, comprising a hollow body having a connector, a sound-absorbing insert in the body and an inner component, the sound-absorbing insert comprising at least one split sheet of closed-pore foamed plastic material having a thickness of less than its average pore-size. Advantageously the sheet material comprises closed-pore cross-linked foamed polyethylene stacked or wound to provide about 3 to 30 layers, each layer ranging in thickness from about 0.1 to 1.0 mm, having an average pore diameter from about 0.2 to 2 mm and an air permeability from about 0.5 to 200 Rayl, the air permeability of the innermost layer ranging from about 1 to 4 times the air permeability of the outermost layer.

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Weinheim, Germany

Hermann Schilling