Magnetorheological fluid dampers
First Claim
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1. Apparatus for variably damping motion which employs a magnetorheological fluid, said apparatus comprising:
- a) a housing for containing a volume of magnetorheological fluid;
b) a piston adapted for movement within said fluid-containing housing, said pistoni) being comprised of a ferrous metal,ii) incorporating therein a number N of windings of an electrically conductive wire defining a coil which produces magnetic flux in and around said piston, andiii) being configured such that ##EQU14## where Acore =a minimum lateral cross-sectional area of said piston within said coil,Apath =a minimum lateral cross-sectional area of magnetically permeable material defining a return path for said magnetic flux,Apole =a surface area of a magnetic pole of said piston,Bopt =an optimum magnetic flux density for said magnetorheological fluid,Bknee =a magnetic flux density at which said ferrous metal begins to become saturated;
c) valve means associated with one of said housing and said piston for controlling movement of said magnetorheological fluid.
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Abstract
Magnetorheological (MR) fluid dampers are optimized. Dimensional relationships involved in the flow of magnetic flux are related to an operational parametric ratio of magnetic flux density in the fluid to the flux density in the steel. A magnetic valve is utilized to change the flow parameters of the MR fluid and, hence, the operational characteristics of the damper. Several embodiments depicting improved piston designs, including spool as well as toroidal configurations, are disclosed. In addition, both single and twin-tube housing designs are presented.
364 Citations
28 Claims
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1. Apparatus for variably damping motion which employs a magnetorheological fluid, said apparatus comprising:
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a) a housing for containing a volume of magnetorheological fluid; b) a piston adapted for movement within said fluid-containing housing, said piston i) being comprised of a ferrous metal, ii) incorporating therein a number N of windings of an electrically conductive wire defining a coil which produces magnetic flux in and around said piston, and iii) being configured such that ##EQU14## where Acore =a minimum lateral cross-sectional area of said piston within said coil, Apath =a minimum lateral cross-sectional area of magnetically permeable material defining a return path for said magnetic flux, Apole =a surface area of a magnetic pole of said piston, Bopt =an optimum magnetic flux density for said magnetorheological fluid, Bknee =a magnetic flux density at which said ferrous metal begins to become saturated; c) valve means associated with one of said housing and said piston for controlling movement of said magnetorheological fluid. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. Apparatus for variably damping motion using a magnetorheological fluid, said apparatus comprising
a) a housing element for containing a volume of magnetorheological fluid, said housing including a first inner tube and a second outer tube; -
b) means to fluidically interconnect said first and second tubes, said means including at least one first opening near a first end of said first and second tubes and at least one second opening near a second end of said first and second tubes; c) a piston mounted upon a piston rod for movement within said first tube; d) valve means for controlling flow of said magnetorheological fluid associated with at least one of said first and second openings, said valve means including i) passageway means through which said magnetorheological fluid flows; ii) a magnetic coil for altering at least one flow characteristic of said magnetorheological fluid within said housing element to control a flow rate at which said fluid passes through said passageway means; e) pressure relief means for preventing fluid pressure buildup within said housing. - View Dependent Claims (21, 22, 23)
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24. Apparatus for variably damping motion using a magnetorheological fluid, said apparatus comprising
a) a housing containing a volume of magnetorheological fluid; -
b) a piston for movement in said housing through said magnetorheological fluid; c) valve means for controlling movement of said magnetorheological fluid within said housing, said valve means including i) a magnetic coil formed as a plurality of toroidally wound magnet segments for altering at least one flow characteristic of said magnetorheological fluid; ii) a plurality of openings formed between said segments of said coil through which said magnetorheological fluid flows. - View Dependent Claims (25, 26, 27, 28)
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Specification