 Aseismic system |
| Referring initially to FIG. 1 the Improved Aseismic System of the present invention is shown and ... |
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| Dental chair attachment |
| What is claimed is: 1. A dental chair attachment comprising: a cylindrical post; a lower base ... |
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| Method of controlling positions and vibrations and active vibration control apparatus therefor |
| The present invention has an object to provide a method of controlling a level of a vibration ... |
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| Plastic window assembly |
| In accordance with the invention, a plastic window assembly comprises an outer assembly and an ... |
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| Electrically induced radon barriers |
| Accordingly, one object of the present invention is to reduce health risks from exposure to radon ... |
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| Soil liquefaction prevention by electro-osmosis during an earthquake event |
| The present invention provides a method and system for inhibiting the liquefaction of soil beneath ... |
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| Shower apparatus |
| The aim of the present invention is to solve the above-noted problems, eliminating the drawbacks of ... |
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| Bouquet display apparatus |
| To achieve the foregoing and other advantages, the present invention, briefly described, provides a ... |
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| Exterior wall |
| The present invention provides an equivalent wall and, in several respects, a more advantageous ... |
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| Seismic isolation bearing having a tension damping device |
| In view of the aforesaid drawbacks of the conventional displacement controlled seismic isolation ... |
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Vibration damper, in particular for motor vehicles
| Details |
Inventors: Wulff, Gunther; Thoma , Achim; Reusing, Gunther; Irmscher, Stefan; Herdeg, Wolfgang;
Assignee: Fichtel & Sachs AG (Schweinfurt, DE)
Primary Examiner: Butler; Douglas C.
Assistant Examiner:
Attorney, Agent or Firm: Nils H. Ljungman and Associates
Vibration damper, in particular for motor vehicles, including a work cylinder, a work piston fastened to a piston rod and dividing the work cylinder into two work chambers, possibly an equalization chamber and a piston rod guide which seals the piston rod against the atmosphere, whereby the work chambers are filled with a magnetorheological fluid to which an electric coil can be applied. In the event of a failure or malfunction of the electric coil, it must be possible to achieve a safe damping force, by having at least one permanent magnetic field which acts on the magnetorheological fluid. |
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DETAILED DESCRIPTION The present invention teaches that the above object can be achieved, in accordance with at least one preferred embodiment, by applying at least one permanent magnetic field to the magnetorheological fluid.
One advantage of this solution is that, by the application of one or more permanent magnetic fields, an initial stress or prestress can be applied to the fluid, i.
e.
the permanent magnetic flux increases the viscosity of the magnetorheological fluid to a value which produces a damping force which ensures the safety of the motor vehicle.
In an additional embodiment, the invention teaches that at least one permanent magnet is provided as the permanent magnetic field.
In one favorable embodiment, the permanent magnetic field is compensated or reinforced by an additional magnetic field.
In this case, the additional magnetic field can advantageously be varied by means of an electric coil.
In this embodiment, it is advantageous that the magnetic field can be increased or decreased by the current applied by the coil, as a function of the current strength and polarity, so that the viscosity of the magnetorheological fluid can be increased or decreased.
That results in a variably adjustable damping force of the vibration damper.
In an additional embodiment, the work piston is provided at least partly with flow channels.
The flow channels can advantageously be designed as holes or as recesses.
In an additional favorable embodiment, the recesses are provided with a width which varies.
The work piston can also preferably be provided with grooves in its area adjacent to the flow channels.
The grooves are thereby advantageously provided with a groove base, the depth of which varies.
It is thereby advantageous that the work piston is guided in a sealed manner with respect to the work cylinder, and that the magnetorheological fluid flows through the piston.
On account of the particular shape of the flow channels, whereby the width of the recess changes over the circumference, and the depth of the groove base can also be varied over the circumference, a resistance for the magnetic flux is created, which reduces the induction in the flow channel (i
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Vibration and Earthquake Isolation 
