Patent US4957644A successfully refreshed from Google Patents.
US4957644A
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Magnetically controllable couplings containing ferrofluids
Assignee: Individual
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Filing: 1989-06-27
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Granted: 1990-09-18
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Expires: 2009-06-27
Abstract
Abstract This invention discloses a new ferrofluid and the use of ferrofluids in magnetically controllable couplings such as electromagnetic clutches and brakes. The new ferrofluid is comprised of a stable suspension of magnetizable particles having a size of at least one micron, a fluid carrier and a complexing agent. The complexing agent maintains the magnetizable particles in suspension within the carrier fluid.
Inventors
- 👤 John T. Price
- 👤 Jurgen M. Kruse
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 05:32
CPC Classifications
C; C10; C10M; C10M169/00; C10M169/04; F; F16; F16D; F16D37/00; F16D37/02; H; H01; H01F; H01F1/00; H01F1/44; H01F1/447; C10M2201/00; C10M2201/04; C10M2201/05; C10M2201/053; C10M2201/06; C10M2201/061; C10M2201/085; C10M2201/16; C10M2201/18; C10M2203/00; C10M2203/02; C10M2203/0206; C10M2203/022; C10M2203/024; C10M2203/04; C10M2205/00; C10M2207/00; C10M2207/28; C10M2207/282; C10M2207/284; C10M2207/285; C10M2207/34; C10M2215/00; C10M2215/02; C10M2215/04; C10M2223/00; C10M2223/02; C10M2223/04; C10M2223/041; C10M2223/042; C10N; C10N2010/00; C10N2010/14; C10N2010/16; C10N2040/00; C10N2040/08; C10N2040/14; C10N2040/16; C10N2040/17; C10N2040/175; C10N2040/18; C10N2040/185; F16D2037/002; F16D2037/005
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
73 words
A magnetic flux transmitting ferrofluid comprising a stable suspension of magnetizable particles having a size of at least one micron, a carrier fluid, and a complexing agent, wherein the complexing agent comprises a chelating agent that forms a multiple coordinate bond with the magnetizable particles which are maintained in suspension within the carrier fluid such that the ferrofluid transmits a substantial magnetic flux without substantial separation of the particles from the carrier fluid.
Claim 2
Dependent Claim
73 words
A magnetic flux transmitting ferrofluid comprising a stable suspension of magnetizable particles having a size of at least one micron, a carrier fluid, and a complexing agent, wherein the complexing agent comprises a chelating agent that forms a multiple coordinate bond with the magnetizable particles which are maintained in suspension within the carrier fluid such that the ferrofluid transmits a substantial magnetic flux without substantial separation of the particles from the carrier fluid.
Claim 3
Dependent Claim
13 words
A ferrofluid as recited in claim 1, wherein the magnetizable particles are metallic.
Claim 4
Dependent Claim
20 words
A ferrofluid as recited in claim 1, wherein the magnetizable particles range in size from about 35 to 150 microns.
Claim 5
Dependent Claim
20 words
A ferrofluid as recited in claim 3, wherein the magnetizable particles range in size from about 40 to 75 microns.
Claim 6
Dependent Claim
16 words
A ferrofluid as recited in claim 1, wherein the carrier fluid is a non-polar organic solvent.
Claim 7
Dependent Claim
15 words
A ferrofluid as recited in claim 1, wherein the carrier fluid comprises a hydrocarbon oil.
Claim 8
Dependent Claim
17 words
A ferrofluid as recited in claim 1, wherein the carrier fluid further comprises a 100% synthetic oil.
Claim 9
Dependent Claim
29 words
A ferrofluid as recited in claim 16, wherein the chelating agent is selected from the group consisting of disodium ethylene diamine tetraacetic acid, tri-butylphosphate, pyrophosphates and fatty acid diamines.
Claim 10
Dependent Claim
99 words
A ferrofluid comprising a stable suspension of magnetizable particles ranging in size from 35 to 150 microns, a complexing agent selected from the group consisting of disodium ethylene diamine tetraacetic acid, tri-N-butyl phosphate, dialkyl acid pyrophosphates, and a fatty acid diamine, and a hydrocarbon oil as a carrier fluid, the complexing agent being bonded to each particle and solvated with the carrier fluid to encapsulate each particle, the ferrofluid being positioned in a magnetic field such that the complexing agent maintains the magnetizable particles in suspension within the hydrocarbon oil to transmit a substantial magnetic flux through the ferrofluid.
Claim 11
Dependent Claim
99 words
A ferrofluid comprising a stable suspension of magnetizable particles ranging in size from 35 to 150 microns, a complexing agent selected from the group consisting of disodium ethylene diamine tetraacetic acid, tri-N-butyl phosphate, dialkyl acid pyrophosphates, and a fatty acid diamine, and a hydrocarbon oil as a carrier fluid, the complexing agent being bonded to each particle and solvated with the carrier fluid to encapsulate each particle, the ferrofluid being positioned in a magnetic field such that the complexing agent maintains the magnetizable particles in suspension within the hydrocarbon oil to transmit a substantial magnetic flux through the ferrofluid.
Claim 12
Dependent Claim
16 words
The ferrofluid of claim 9 wherein the ferrofluid has a specific gravity of at least 3.0.
Claim 13
Independent Claim
74 words
A method of magnetically coupling members with a ferrofluid comprising: providing a ferrofluid having magnetizable particles suspended in the ferrofluid with a chelating agent; positioning the ferrofluid in a cavity between adjacent moveable members; and applying a magnetic field between the members and through the ferrofluid in the cavity such that the particles are substantially maintained in suspension within the ferrofluid positioned within the magnetic field and transmit a coupling force between the members.
Claim 14
Independent Claim
74 words
A method of magnetically coupling members with a ferrofluid comprising: providing a ferrofluid having magnetizable particles suspended in the ferrofluid with a chelating agent; positioning the ferrofluid in a cavity between adjacent moveable members; and applying a magnetic field between the members and through the ferrofluid in the cavity such that the particles are substantially maintained in suspension within the ferrofluid positioned within the magnetic field and transmit a coupling force between the members.
Claim 15
Dependent Claim
27 words
The method of claim 11 wherein the chelating agent is selected from the group consisting of disodium ethylene diamine tetraacetic acid, tri-butylphosphate, pyrophosphates and fatty acid diamines.
Claim 16
Dependent Claim
13 words
The method of claim 11 wherein said members rotate relative to each other.
Claim 17
Dependent Claim
16 words
The method of claim 11 wherein one member transmits an accelerating force to the adjacent member.
Claim 18
Dependent Claim
16 words
The method of claim 11 wherein one member transmits a decelerating force to the adjacent member.
Claim 19
Independent Claim
116 words
A method of magnetically coupling members comprising: providing a ferrofluid positioned in a cavity between first and second coupling members, the ferrofluid comprising a carrier fluid and a complexing agent that is bonded to a plurality of magnetizable particles that are suspended in the carrier fluid, the complexing agent being solvated with the carrier fluid such that each particle is encapsulated in a solvated sphere which maintains the particles in suspension; applying a magnetic field to the ferrofluid to transmit a magnetic flux between the coupling members such that the particles are substantially maintained in suspension within the magnetized ferrofluid; and moving the first member relative to the second member to transmit force between the members.
Claim 20
Independent Claim
116 words
A method of magnetically coupling members comprising: providing a ferrofluid positioned in a cavity between first and second coupling members, the ferrofluid comprising a carrier fluid and a complexing agent that is bonded to a plurality of magnetizable particles that are suspended in the carrier fluid, the complexing agent being solvated with the carrier fluid such that each particle is encapsulated in a solvated sphere which maintains the particles in suspension; applying a magnetic field to the ferrofluid to transmit a magnetic flux between the coupling members such that the particles are substantially maintained in suspension within the magnetized ferrofluid; and moving the first member relative to the second member to transmit force between the members.
Claim 21
Dependent Claim
15 words
The method of claim 16 wherein the second member is concentric about the first member.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1993-09-17 | 1994-03-19 | 1994-09-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-09-17 | 1998-03-19 | 1998-09-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-09-17 | 2002-03-19 | 2002-09-18 | $7700.00 | Window Closed / Lapsed |