US5354488A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Fluid responsive to a magnetic field
Assignee: Diametrics Medical Ltd
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Filing: 1992-10-07
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Granted: 1994-10-11
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Expires: 2012-10-07
Abstract
Abstract A rheological fluid composition which is responsive to a magnetic field. The composition comprises a vehicle, magnetizable particles suspended in the vehicle and a dispersant. The dispersant comprises particles having no dimension greater than 10 nanometers. The dispersant is preferably carbon.
Inventors
- 👤 Emil M. Shtarkman
- 👤 John A. Starkovich
- 👤 William W. Davison
- 👤 Hsiao-Hu Peng
- 👤 Thomas J. Fitzgerald
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 05:02
CPC Classifications
F; F16; F16F; F16F9/00; F16F9/32; F16F9/53; F16F9/535; H; H01; H01F; H01F1/00; H01F1/44; H01F1/447
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
77 words
A rheological fluid composition which is responsive to a magnetic field, said fluid comprising: a vehicle; magnetizable particles suspended in said vehicle; and a dispersant comprising small, non-magnetizable, dispersant particles which are insoluble in the vehicle, having no dimension greater than 10 nanometers, in an effective amount to provide a thin coating of dispersant particles on the surface of each of the magnetizable particles; said dispersant particles being reversibly bonded to the surface of the magnetizable particles.
Claim 2
Dependent Claim
77 words
A rheological fluid composition which is responsive to a magnetic field, said fluid comprising: a vehicle; magnetizable particles suspended in said vehicle; and a dispersant comprising small, non-magnetizable, dispersant particles which are insoluble in the vehicle, having no dimension greater than 10 nanometers, in an effective amount to provide a thin coating of dispersant particles on the surface of each of the magnetizable particles; said dispersant particles being reversibly bonded to the surface of the magnetizable particles.
Claim 3
Dependent Claim
35 words
The composition of claim 1 wherein the vehicle is present in an effective amount to wet the surfaces of the magnetizable particles and the dispersant particles and to fill the voids between the magnetizable particles.
Claim 4
Dependent Claim
25 words
The composition of claim 1 wherein the amount of said dispersant particles is about 0.1-20 volume percent based on the volume of the magnetizable particles.
Claim 5
Dependent Claim
28 words
The composition of claim 3 wherein said vehicle is present in the amount of 10-100 volume percent based on the combined volume of the magnetizable particles and dispersant.
Claim 6
Dependent Claim
23 words
The composition as set forth in claim 1 wherein said dispersant particles have a diameter of from about two nanometers to 10 nanometers.
Claim 7
Dependent Claim
67 words
The composition as set forth in claim 1 wherein said dispersant is selected from the group consisting of carbon, aluminum, boron, non-magnetizable iron, silicon, and germanium; carbides, oxides, and nitrides of aluminum, boron, germanium, hafnium, iron, silicon, tantalum, titanium, tungsten, yttrium, zirconium; Group 1 metal and Group 2 metals compounds; silicon and siloxane organic polymers; non-silicon containing phenolics, epoxies, and polyimides, and silica-siloxane polymers, and mixtures thereof.
Claim 8
Dependent Claim
13 words
A composition as set forth in claim 1 wherein said dispersant is carbon.
Claim 9
Dependent Claim
18 words
A composition as set forth in claim 1 wherein said magnetizable particles are electrically insulated reduced carbonyl iron.
Claim 10
Dependent Claim
39 words
A composition as set forth in claim 1 wherein said dispersant is carbon particles with a diameter of from about 2 nanometers to 10 nanometers and a surface area of about 250 to about 2,500 square meters per gram.
Claim 11
Dependent Claim
11 words
The composition of claim 1 in which said fluid is homogenized.
Claim 12
Dependent Claim
18 words
The composition of claim 1 comprising 1-7 volume percent dispersant particles based on the volume of magnetizable particles.
Claim 13
Dependent Claim
44 words
A rheological fluid composition which is responsive to a magnetic field, said fluid consisting essentially of: a vehicle; magnetizable particles suspended in said vehicle; and a dispersant consisting essentially of a plurality of particles each of which has no dimension greater than 10 nanometers.
Claim 14
Dependent Claim
44 words
A rheological fluid composition which is responsive to a magnetic field, said fluid consisting essentially of: a vehicle; magnetizable particles suspended in said vehicle; and a dispersant consisting essentially of a plurality of particles each of which has no dimension greater than 10 nanometers.
Claim 15
Dependent Claim
54 words
A rheological fluid composition which is responsive to a magnetic field, said fluid consisting essentially of: a vehicle; magnetizable particles suspended in said vehicle, said magnetizable particles comprising electrically insulated reduced carbonyl iron; and a dispersant consisting essentially of a plurality of particles each of which has no dimension greater than about 10 nanometers.
Claim 16
Dependent Claim
54 words
A rheological fluid composition which is responsive to a magnetic field, said fluid consisting essentially of: a vehicle; magnetizable particles suspended in said vehicle, said magnetizable particles comprising electrically insulated reduced carbonyl iron; and a dispersant consisting essentially of a plurality of particles each of which has no dimension greater than about 10 nanometers.
Claim 17
Dependent Claim
67 words
A composition as set forth in claim 13 wherein said dispersant is selected from the group consisting of carbon, aluminum, boron, non-magnetizable iron, silicon, and germanium; carbides, oxides, and nitrides of aluminum, boron, germanium, hafnium, iron, silicon, tantalum, titanium, tungsten, yttrium, zirconium; Group 1 metal and Group 2 metal compounds; silicon and siloxane organic polymers; non-silicon containing phenolics, epoxies, and polyimides, and silica-siloxane polymers; and mixtures thereof.
Claim 18
Dependent Claim
13 words
A composition as set forth in claim 13 wherein said dispersant is carbon.
Claim 19
Dependent Claim
26 words
A composition as set forth in claim 15 wherein said dispersant is carbon particles having a diameter of from about 2 nanometers to about 10 nanometers.
Claim 20
Dependent Claim
27 words
A composition as set forth in claim 16 wherein said dispersant particles have a surface area of from about 250 to about 2,500 square meters per gram.
Claim 21
Dependent Claim
12 words
A shock absorber which contains the rheological fluid composition of claim 1.
Claim 22
Dependent Claim
11 words
A clutch which contains the rheological fluid composition of claim 1.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1997-10-10 | 1998-04-11 | 1998-10-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-10-10 | 2002-04-11 | 2002-10-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-10-10 | 2006-04-11 | 2006-10-11 | $7700.00 | Window Closed / Lapsed |