Magnetorheological compositions

• US 6,395,193 B1
• Filed: 05/03/2000
• Issued: 05/28/2002
• Est. Priority Date: 05/03/2000
• Status: Expired due to Fees

• Current Assignee: Lord Corporation (Parker-Hannifin Corporation)
• Original Assignee: Lord Corporation (Parker-Hannifin Corporation)
• Inventors: Kintz, K. Andrew, Forehand, Teresa L.
• Primary Examiner(s): KOSLOW, CAROL M
• Application Number:
  US09/564,124
• Time in Patent Office: 755 Days
• Field of Search: 252/62.52,62.51 R,62.5 C
• US Class Current: 252/62.52
• CPC Class Codes: H01F 1/447 characterised by magnetoviscosity, e.g. magnetorheological, magnetothixotropic, magnetodilatant liquids electrorheological fluids C10M171/001

Abstract

The invention provides a magnetorheological composition having reduced off-state forces and good performance. Specifically, this invention is directed to a magnetorheological composition that may comprise non-sperical magnetic-responsive particles and at least one friction-reducing additive that reduces the interparticle friction between the magnetic-responsive particles.

Claims

1. A magnetorheological fluid comprising a carrier fluid and a magnetorheological composition comprising magnetic-responsive particles and at least one additive that reduces interparticle friction between the magnetic-responsive particles wherein the additive is an inorganic molybdenum compound, a fluorocarbon polymer, or mixtures thereof.

2. The magnetorheological fluid of claim 1 wherein the additive is present in an amount of about 0.1 to about 10 weight percent of the magnetic-responsive particles.

3. The magnetorheological fluid of claim 1 wherein the magnetic-responsive particles and at least one additive are provided as a substantially dry powder.

4. The magnetorheological fluid of claim 1 wherein the magnetic-responsive particles are non-spherical in shape.

5. The magnetorheological fluid of claim 1 wherein the magnetic-responsive particles are provided in an amount of about 60 to about 90 weight percent of the total magnetorheological composition.

6. The magnetorheological fluid of claim 4 wherein the magnetic-responsive particles comprise iron particles containing less than 0.01% carbon.

7. The magnetorheological fluid of claim 1 wherein the additive is a molybdenum sulfide or a molybdenum phosphate.

8. The magnetorheological fluid of claim 7 wherein the additive is molybdenum disulfide.

9. The magnetorheological fluid of claim 1 wherein the additive is a fluorocarbon polymer.

10. The magnetorheological fluid of claim 9 wherein the additive is polytetrafluoroethylene.

26. The magnetorheological fluid of claim 1 wherein the magnetic-responsive particles have an average number diameter distribution of about 6 to about 100 microns.

27. The magnetorheological fluid of claim 26 wherein the magnetic-responsive particles have an average number diameter distribution of about 10 to about 60 microns.

28. The magnetorheological fluid of claim 27 wherein the magnetic-responsive particles have an average number diameter distribution of about 15 to about 30 microns.

29. The magnetorheological fluid of claim 27 wherein the additive is a molybdenum sulfide or a molybdenum phosphate.

30. The magnetorheological fluid of claim 27 wherein the additive is polytetrafluoroethylene.

11. A magnetorheological fluid comprising non-spherical magnetic-responsive particles having an average number diameter distribution of about 15 to about 30 microns, a carrier fluid, and at least one additive that reduces interparticle friction between the magnetic-responsive particles.

12. The magnetorheological fluid of claim 11 wherein the additive is an inorganic molybdenum compound.

13. The magnetorheological fluid of claim 12 wherein the carrier fluid is selected from the group consisting of cycloparaffin oil, paraffin oil, natural fatty oil, mineral oil, polyphenylether, dibasic acid ester, neopentylpolyol ester, phosphate ester, polyester, synthetic cycloparaffin oil, synthetic paraffin oil, unsaturated hydrocarbon oil, synthetic hydrocarbon oil, monobasic acid ester, glycol ester, glycol ether, silicate ester, silicone oil, silicone copolymer, perfluorinated polyether, perfluorinated ester, halogenated hydrocarbon, and mixtures or blends thereof.

14. The magnetorheological fluid of claim 13 wherein the carrier fluid is mineral oil, paraffin oil, cycloparaffin oil, synthetic hydrocarbon oil, or mixtures or blends thereof.

15. The magnetorheological fluid of claim 12 wherein the inorganic molybdenum compound is a molybdenum sulfide or a molybdenum phosphate.

16. The magnetorheological fluid of claim 12 wherein the inorganic molybdenum compound is molybdenum disulfide.

17. The magnetorheological fluid of claim 15, further comprising one or more of a thixotropic agent, a carboxylate soap, an antioxidant, a lubricant or a viscosity modifier.

18. The magnetorheological fluid of claim 11 wherein the non-spherical magnetic-responsive particles comprise iron particles containing at least about 95% iron obtained by water atomization.

19. The magnetorheological fluid of claim 11 wherein the additive is a fluorocarbon polymer.

20. The magnetorheological fluid of claim 19 wherein the additive is polytetrafluoroethylene.

21. The magnetorheological fluid of claim 19 wherein the carrier fluid is mineral oil, paraffin oil, cycloparaffin oil, synthetic hydrocarbon oil, or mixtures or blends thereof.

22. The magnetorheological fluid of claim 15 wherein the non-spherical magnetic-responsive particles comprise iron particles having at least about 95% iron obtained by water atomization.

23. The magnetorheological fluid of claim 19 wherein the non-spherical magnetic-responsive particles comprise iron particles having at least about 95% iron obtained by water atomization.

24. A magnetorheological fluid comprising a carrier fluid and a magnetorheological composition comprising non-spherical magnetic-responsive particles having an average number diameter distribution of about 10 to about 60 microns and molybdenum disulfide or polytetrafluoroethylene in an amount of about 0.1 to about 10 weight percent of the magnetic-responsive particles.

25. A magnetorheological fluid comprising non-spherical magnetic-responsive particles having an average number diameter distribution of about 15 to about 30 microns and produced by water atomization, at least one additive that reduces the interparticle friction between the magnetic-responsive particles, and a carrier fluid.

31. A magnetorheological fluid comprising a carrier fluid and a magnetorheological composition comprising magnetic-responsive particles having an average number diameter distribution of about 15 to about 30 microns and at least one additive that reduces interparticle friction between the magnetic-responsive particles.

32. The magnetorheological fluid of claim 31 wherein the additive is present in an amount of about 0.1 to about 10 weight percent of the magnetic-responsive particles.

33. The magnetorheological fluid of claim 31 wherein the magnetic-responsive particles and at least one additive are provided as a substantially dry powder.

34. The magnetorheological fluid of claim 31 wherein the magnetic-responsive particles are provided in an amount of about 60 to about 90 weight percent of the total magnetorheological composition.

35. The magnetorheological fluid of claim 31 wherein the carrier fluid is selected from the group consisting of cycloparaffin oil, paraffin oil, natural fatty oil, mineral oil, polyphenylether, dibasic acid ester, neopentylpolyol ester, phosphate ester, polyester, synthetic cycloparaffin oil, synthetic paraffin oil, unsaturated hydrocarbon oil, synthetic hydrocarbon oil, monobasic acid ester, glycol ester, glycol ether, silicate ester, silicone oil, silicone copolymer, perfluorinated polyether, perfluorinated ester, halogenated hydrocarbon, and mixtures or blends thereof.

36. The magnetorheological fluid of claim 35 wherein the carrier fluid is mineral oil, paraffin oil, cycloparaffin oil, synthetic hydrocarbon oil, or mixtures or blends thereof.

37. The magnetorheological fluid of claim 31 further comprising one or more of a thixotropic agent, a carboxylate soap, an antioxidant, a lubricant or a viscosity modifier.