Magnetorheological fluid devices

• US 5,284,330 A
• Filed: 06/18/1992
• Issued: 02/08/1994
• Est. Priority Date: 06/18/1992
• Status: Expired due to Term

• Current Assignee: Lord Corporation (Parker-Hannifin Corporation)
• Original Assignee: Lord Corporation (Parker-Hannifin Corporation)
• Inventors: James, Frank O., Carlson, J. David, Chrzan, Michael J.
• Primary Examiner(s): Oberleitner, Robert J.
• Assistant Examiner(s): SCHWARTZ, CHRISTOPHER P
• Application Number:
  US07/900,567
• Time in Patent Office: 600 Days
• Field of Search: 188/267, 267/140.14, 267/219, 267/35, 267/141.2, 267/141.3
• US Class Current: 267/140.14
• CPC Class Codes: F16F 13/305 magnetorheological
• CPC Class Codes: F16F 9/535 Magnetorheological [MR] fluid dampers springs comprising magnetorheological [MR] elastomers F16F1/361
• CPC Class Codes: H01F 1/447 characterised by magnetoviscosity, e.g. magnetorheological, magnetothixotropic, magnetodilatant liquids electrorheological fluids C10M171/001

Abstract

This invention relates to sealless designs of magnetorheological fluid dampers. With these sealless designs a piston rod extends above and below a piston head within a cylindrical housing and has frustoconical elastomer elements attached to and between the rod and housing to allow translation of the piston head and rod. The piston head has a coil contained radially therein that produces magnetic flux in and around the piston. The advantages of utilizing an MR fluid according to the invention include magnetic fields which are easily produced by low voltage electromagnetic coils, damping effects which are velocity independent, and higher yield strength obtained by the MR fluid capable of generating greater damping forces.

Claims

1. Apparatus for damping motion between first and second relatively movable members, said apparatus comprising:

a) a housing containing a volume of magnetorheological fluid;

b) first means for attaching said housing to one of said movable members;

c) a piston rod mounted for relative movement with respect to said housing;

d) second means for attaching said piston rod to another one of said first and second movable members;

e) a first block of elastomer interconnecting said housing and said piston rod, said block being fixedly attached to each of said housing and a first end of said piston rod, said block of elastomer forming at least a portion of a first fluid-containing chamber for said magnetorheological fluid;

f) a second block of elastomer interconnecting said housing and said piston rod, said block being fixedly attached to each of said housing and a second end of said piston rod and, together with said first block, functioning as the sole means for permitting said piston rod to move relative to said housing, said second block of elastomer forming at least a portion of a second fluid-containing chamber for said magnetorheological fluid;

g) a piston attached to an intermediate portion of said piston rod for movement therewith which divides said first fluid-containing chamber from a second fluid-containing chamber for said magnetorheological fluid, substantially all of the movement of said piston being accommodated by flow of fluid past said piston;

h) valve means for permitting magnetorheological fluid to flow from and to said first fluid-containing chamber to and from said second fluid-containing chamber, said valve means including

i) aperture means for permitting said flow,

ii) a magnetic coil associated with said aperture means for controlling said flow therethrough,

whereby a desired level of damping of said relative movement is provided.

2. Apparatus according to claim 1 wherein said aperture means comprises a gap formed between an outside perimeter of said piston head and an inside perimeter of said housing.

3. Apparatus according to claim 2 wherein said magnetic coil is formed integrally upon said piston head.

4. Apparatus according to claim 1 wherein said first and second blocks of elastomer is each comprised of a pair of disc-shaped elements, a first such disc-shaped element being attached about its outer periphery to said housing and about its inner periphery to an intermediate member adapted for movement with said intermediate member.

5. Apparatus according to claim 4 wherein a second of said pair of disc-shaped elements has an outer periphery attached to an inner periphery of said intermediate member and an inner periphery attached to said piston rod.

6. Apparatus according to claim 1 further comprising an auxiliary chamber associated with one of said first and second fluid-containing chambers, said auxiliary chamber being chargeable with a second compressible fluid to modify a response property of said piston head.

7. Apparatus for variably damping motion using a magnetorheological fluid, said apparatus comprising

a) a housing containing a volume of magnetorheological fluid;

b) a piston adapted for movement within said housing through said magnetorheological fluid, said piston connected to a piston rod for movement therewith;

c) valve means including

i) a magnetic coil associated with said housing and said piston for modifying at least one flow characteristic of said magnetorheological fluid, and

ii) passageway means through which said magnetorheological fluid flows;

d) elastomer block means at each end of said piston rod, wherein each of said elastomeric block means is formed as twin disc-shaped elements, a first disc shaped element element being fully bonded about its outer periphery to said cylindrical housing and also having a cylindrical aperture which is fully bonded to an outer periphery of a first end of an interconnecting element and a second disc shaped element element which has a central aperture that is fully bonded about its inner periphery to a piston rod and about its outer periphery to a second end of said interconnecting element;

whereby each end of said piston rod is fully sealed against loss of magnetorheological fluid.