Messerschmitt-boelkow-blohm Gesellschaft MIT Beschraenkter Haftung

Messerschmitt-bolkow-blohm Gmbh

Messerschmitt-boelkow-blohm Gmbh

American Technology Corporation

Messerschmitt-bolkow-blohm Gesellschaft MIT Beschrankter Haftung

Dofasco Inc.

Oskar Bschorr

Helmut Albrecht

Hans-Joachim Raida

Hans Spies

Gerhard Lobert

Helmut Hassel

Eckehard Laudien

A vibration damping roll is provided for rolling contact with a vibrating structure. The vibration damping roll incorporates a wave guide consisting of radially alternating rigid and flexible material having at least two rigid elements disposed adjacent to flexible material and may be provided in the form of a layered structure, a spiral structure, or a plurality of discrete rigid elements disposed in a matrix of flexible material.

Vibration damping roll

An ultrasonic beam (19) is used as a virtual array for an acoustic directional transmitter (11,21,31,41,51, and 61). The acoustic useful signal is modulated upon the ultrasonic beam as carrier via amplitude modulation, for example. The absorption of the ultrasonic power produces thermal expansion of the air and thus acoustic monopole radiation. At the same time, radiation pressure is released, resulting in dipole radiation. The superimposition of monopole and dipole produces a marked directivity characteristic. Since the ultrasonic sound possesses the same propagation velocity as the useful sound, the monopole and dipole radiation takes place within the virtual array correctly in terms of transit time, resulting in radiation that is directed extremely in the propagation direction. The effective array length can be adjusted over a wide range using the absorption coefficient that is a function of the carrier-frequency and, in extreme cases, a very punctual acoustic radiation can be realized at a wide distance. These types of directional transmitters are suitable as anti-sound generators and for directional signal and sound transmission. The ultrasonic carriers can be realized via piezoelectric (12) or pneumatic ultrasonic transmitters (22,32,42,52, and 62).

Directed radiator with modulated ultrasonic sound

A device for reducing the frictional drag inherent in flow mechanics in airborne, waterborne and space vehicles in which the surface of a body in a flowing medium is provided with an asymmetrical microstructure in the form of grooved profiles whose dimensions do not essentially exceed the average free travel length of the molecules of the medium.

Device for reducing the frictional drag of moving bodies

The running characteristics of a tire for a wheel are improved to provide a more quiet run, by attaching to an inner and/or outer surface of the tire vibration absorbing elements. Vibration absorbing elements may even be inserted into the tire material itself. The vibration absorbing elements are secured to the tire surface in a force and moment or torque transmitting manner by vulcanization or by a suitable adhesive. A strap may hold the individual absorbing elements together or the elements may form integral parts of the strap which is secured to the tire surface, for example, by a rubber vulcanizing operation. The vibration absorber elements may be secured to an inner tube instead of to the tire.

Wheel tire with noise absorbing means

The noise caused by vehicle tires rolling on a road surface is reduced by enclosing in the space confined by the tire and the wheel rim a noise or sound absorbing or insulating material which may assume various shapes. This noise absorbing or insulating material may be connected to the inner tire surface or to the rim surface facing into the tire. Thus, the material is not externally visible once the tire has been mounted on the wheel rim.

Tire with open cell foam insert for reducing noise

The noise of an exhaust gas flow of an internal combustion engine or other hermodynamic equipment is reduced by silators which are operatively arranged for deadening or absorbing the exhaust noise. Such silators have vaulted surfaces enclosing an evacuated volume which may include a cooling liquid. The silators have a resonance frequency that depends on the vaulting height and the free span or diameter of the vaulted surface. By properly dimensioning the silators and combining a plurality thereof each having a different resonance frequency, a wide frequency range of exhaust noises may be covered. Preferably the silator impedance is smaller than the air impedance of the environment. The silators are protected against the heat of the exhaust gases.

Apparatus for reducing the exhaust noise of internal combustion engines

A noise reducing resonator, herein referred to as a silator due to its no silencing quality, is made up of primary struts forming a main frame and secondary struts forming at least one subframe enclosed by a vacuum tight cover to enclose a vaulting evacuated volume. Each frame has a given span width and a vaulting height corresponding to 0.005 to 0.05 times the respective span width. The frames are arranged in a hierarchic order which means that a larger main frame holds a smaller subframe which in turn holds a still smaller subframe and so on. The resonance frequency increases with the number of subframes held in a main frame. Interconnected silators may cover entire surface areas for noise reduction or absorption.

Noise reducing resonators, or so-called silators

The present noise and heat insulating structural component may form a wall anel or a window element if the component is made of transparent material. Between two substantially parallel outer walls there is arranged at least one auxiliary damping wall forming a plurality of evacuated pockets each having a vaulted or domed surface when the auxiliary wall is substantially free of a load condition. The auxiliary wall may be secured to one or both of the outer walls, for example, by adhesive. Alternatively the auxiliary damping wall may be secured to a further inner wall member or it may be held in position only at its edges substantially intermediate between the outer walls.

Noise and heat insulating structural component

A wide-band vibration damper for damping sound propagating in a solid body includes at least one horn member having a broad end or side and a tapering end. The broad horn side or end is rigidly connected to the solid body which is to be dampened in its vibration. The tapering end of the horn member is connected to a supporting rigid point through a damping material such as a foam material or the like.

Wide-band vibration damper

The present variable volume resonators have an inner volume enclosed by wall members constructed as Belleville springs. The wall members confine in said volume a pressure which is reduced relative to atmospheric pressure, whereby the springs have a small spring constant in response to a reduced pressure load. Each resonator is so constructed that it has a relatively large resonating surface and a relatively low resonating mass. The sound damping effect of the resonator volume is enhanced by means of various types of damping devices including a high viscosity residual gas, wire mesh members, or liquid drops in the volume interior. The present resonators also comprise features for compensating air pressure and/or the resonance frequency.

Variable volume resonators using the Belleville spring principle

The present noise damping apparatus is especially intended for damping the noise caused by wheels running on rails. For this purpose there is provided a noise screen connected to at least one surface of the rail wheel in a force transmitting, yet removable manner. The noise screen comprises vibration damping reed members. This screen prevents noise generated by the wheel proper from radiating outwardly and it also acts as a noise absorber for the impact noise propagating in the wheel and other solid bodies.

Railway flanged wheel vibration dampening assembly

The present noise absorbing or damping devices are shaped as funnels or horns of various configurations which may be coiled, spiraled, rolled and/or bent or twisted. The open funnel mouth of each funnel faces toward the source of the noise. The volume confined by the funnel walls may be filled with noise absorbing material such as an open cell foam. Preferably at least the funnel neck is filled with such material. A plurality of funnels may be arranged on the walls of a room and the funnel mouths facing into the room may be covered with blankets or mats of noise absorbing material.

Noise absorbing device

The present noise reducing apparatus includes resonators which have a small and variable volume as well as a high admittance. For this purpose the resonators constitute vibrating systems having at least one volume wherein the pressure is reduced below atmospheric pressure to provide a reduced volume stiffness. The volume is confined by wall elements having a very small or a negative spring rate under reduced pressure inside said volume.

Noise reducing resonator apparatus

A damper for sound conducted or propagating in solids is constructed to ecially damp oscillations or vibrations of the bending type particularly in plates, housings, girders, rails, rods, etc. The damper is connected to the structural member to be damped in such a manner that the damping force is taken up by the structure member itself. For this purpose a damping element having a high rigidity against bending is secured longitudinally to a structural member to be damped. The structural member and the element form the damping unit. Due to the high flexural rigidity, the damping element behaves like a solid platform or a fixed point, such that vibrations of the structural member cause a relative motion between the structural member and the damping element. This relative motion provides excellent damping characteristics which may even be improved by placing a viscous damping material between the structural member and the element.

Damper for sound conducted in solids

A vibration damper for damping sound propagating in solids includes vibran damping horn members connected through a damping material to a support point on the surface of the solid in such a manner that a tapering portion of the horn member contacts the solid through the damping material. The taper in a horn member, for example of circular cross section, is considered to be the curvature of the horn member away from a generatrix of the horn member. The damping factor of the connecting damping material is equal or substantially equal to the terminal impedance of the horn member.

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Munich, Germany

Oskar Bschorr