Lord Corporation

Theodore G Duclos

J David Carlson

Douglas A Hodgson

Keith D Weiss

Kirk J Abbey

Michael J Chrzan

Lynn C Yanyo

John P Coulter

A magnetorheological material containing a particle component and a carrier fluid or mixture of carrier fluids having a change in viscosity per degree temperature (.DELTA..eta./.DELTA.T ratio) less than or equal to about 16.0 centipoise/.degree.C. over the temperature range of about 25.degree. C. to -40.degree. C. The magnetorheological material exhibits a substantial magnetorheological effect and excellent lubricating properties with a minimal variation in mechanical properties with respect to changes in temperature. The magnetorheological material is advantageous in that it provides for the design of devices that are smaller, more efficient and consume less power.

Temperature independent magnetorheological materials

Controllable composite structure or structural elements enclose magnetotheological fluids as a structural component between opposing containment layers to form at least a portion of any variety of extended mechanical systems, such as plates, panels, beams and bars or structures including these elements. The control of the stiffness and damping properties of the structure or structural elements is accomplished by changing the shear and compression/tension moduli of the magnetorheological fluid by varying the applied magnetic field. The composite structures of the present invention may be incorporated into a wide variety of mechanical systems for control of vibration and other properties.

Magnetorheological fluid composite structures

A vibration isolator including an electrorheological fluid filled partition assembly for providing variable dynamic stiffness characteristics. The partition assembly separates the variable volume fluid chambers of the isolator and includes movable electrode elements which define therebetween a chamber containing an electrorheological fluid. A fixed electrode is positioned between the movable electrode elements and separates the chamber into upper and lower portions. A plurality of openings extend through the fixed electrode allowing for passage of the electrorheological fluid between the portions in response to movement of the movable electrode elements. The yield stress developed in the electrorheological fluid by application of an electric field constrains movement of the movable electrode elements in response to input excitations thereby providing the isolator with a selectable dynamic stiffness.

Vibration isolator with electrorheological fluid controlled dynamic

The fluid inertia mount of the like has an inertia track with an adjustable fluid path length located between variable volume fluid chambers of the mount. By adjusting the fluid path length of the inertia track the mount may be dynamically tuned continuously between a range of frequencies in a manner to provide a low stiffness notch for isolating input excitations that produce undesirable vehicle vibrations. A tuning plate assembly adjustably locates an opening of the inertia track in a desired location along the length thereof betwene extreme positions in which the fluid path length is relatively long and relatively short.

Mount with adjustable length inertia track

Controllable electrorheological fluid composite structure elements incorporate electrorheological fluids as a structural component between opposing fluid containment layers to form at least a portion of any variety of extended mechanical systems such as plates, panels, beams and bars or structures including these elements. The electrorheological fluid is operatively contained in a region between the containment layers and has complex shear and tensile modulus properties which vary with the electric field applied thereto. A variable power source is utilized to create an electric potential between the layers of the structure element to create the electric field. An alternative power source may include the use of a piezoelectric material layer. In order to maintain the insulation and spacing between the containment layers, a fabric or separating layer having an open mesh is provided which permits the transportation of electrorheological fluid in the region between the layers. Multiple layers and regions are contemplated including orientation orthogonally to the long axis of the structure to take advantage of the elongational modulus of the fluid. The composite structures of the present invention may be incorporated in a wide variety of mechanical systems for control of vibration and other properties.

Electrorheological fluid composite structures

An electrorheological fluid torque transmission and conversion system provides for variable control of torque in clutch and brake applications. Communication of mechanical energy between the drive elements is accomplished by magnetic coupling to eliminate the need for a dynamic fluid seal for interface of moving parts to the interior portion of the electrorheological fluid containment chamber. Permanent magnets are associated respectively with each of a first member and a second member which are magnetically coupled through a surface with low magnetic permeability such that the first member and second members rotate in unison. A variety of permanent arrangements may be utilized. Further, the drive element internal to the electrorheological fluid chamber may be both mechanically and electrically decoupled. A floating electrode may be capacitively coupled through the fluid to the power supply. Also provided are inner and outer conductive plates are provided for increased fluid surface contact area. Spacing between the inner and outer plates is determined by the thickness of inner and outer ring members therebetween, which may be easily removed and replaced for simplified assembly and adjustment. Condition responsive control of the electrorheological fluid torque transmission and conversion system is provided by closed-loop feedback of a signal indicative of rotational speed between the drive elements to the control system. The control system may also incorporate internal power generation to provide a self-contained system which does not require an external power source.

Electrorheological fluid force transmission and conversion device

The mount has variable volume fluid chambers interconnected by fluid passageways and containing electrorheological fluid. Valves are arranged in series with a plurality of the passageways. Each valve has a flow area greater than that of the passageway in series therewith. Energization of a valve generates an electrical field effective to so increase the apparent viscosity of the fluid within the valve as to prevent fluid flow through the passageway in series with it. Selective energization of the valves, by suitable controls associated therewith, varies the frequencies at which fluid inertia forces cause the mount to undergo abrupt changes in dynamic stiffness. The valves may be located upon opposite sides of a central mount section through which the chamber connecting passages extend. Electrode elements of the valves are preferably so shaped as to minimize fluid drag and electrical concentration. In one embodiment the passageways all communicate at one end with a common variable volume chamber, while communicating at their opposite ends with respective ones of a plurality of different chambers.

Tunable electrorheological fluid mount

The mount includes first and second chambers containing water, glycol or similar conventional hydraulic fluid of low viscosity, and at least a third chamber containing electrorheological fluid that is used to 'tune' the frequencies at which the mount experiences abrupt reduction of dynamic stiffness. The third chamber is contiguous with one of the first and second chambers, and with one end of an inertia track passageway whose opposite end is contiguous with the other of the first and second chambers. Energization of an electrode-type of valve associated with the third chamber produces a high voltage electrical field and fluid solidification within the third chamber. Pressure pulses are transmitted through the third chamber only when the valve is de-energized. The valve has electrode elements which may be of flat or spiral shape. The mount may include additional valved chambers, and additional passageways which preferably are of differing sizes.

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Raleigh, NC, United States of America

Theodore G Duclos