Patent US3848879A successfully refreshed from Google Patents.
US3848879A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Shaft seal
Assignee: United States Department of the Army
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Filing: 1972-12-19
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Granted: 1974-11-19
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Expires: 1992-12-19
Abstract
Abstract A sealing apparatus for use in gearbox/transmission systems which contain fluids miscible with ferrofluids. A ferrofluid seal is combined with a controlled clearance (Labyrinth) seal and a pressurized air cavity, the ferrofluid seal providing the external seal and the controlled clearance seal and the pressurized air cavity preventing the internal fluids from contacting the ferrofluid.
Inventors
- 👤 W Hudgins
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 07:01
CPC Classifications
F; F16; F16J; F16J15/00; F16J15/002; F16J15/16; F16J15/40; F16J15/43
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
91 words
In combination with a gearbox/transmission housing or the like containing a liquid lubricant and having a shaft extending from within; a ferrofluid magnetic sealing means interposed between the shaft and housing and encircling the shaft at the point of exit from the housing; a pressurized air supply cavity spaced axially inward next to the said ferrofluid magnetic sealing means; and a controlled clearance labyrinth seal spaced axially inward next to the pressurized air supply cavity, thereby preventing the said internally contained liquid lubricant from contacting the said ferrofluid magnetic sealing means.
Claim 2
Dependent Claim
91 words
In combination with a gearbox/transmission housing or the like containing a liquid lubricant and having a shaft extending from within; a ferrofluid magnetic sealing means interposed between the shaft and housing and encircling the shaft at the point of exit from the housing; a pressurized air supply cavity spaced axially inward next to the said ferrofluid magnetic sealing means; and a controlled clearance labyrinth seal spaced axially inward next to the pressurized air supply cavity, thereby preventing the said internally contained liquid lubricant from contacting the said ferrofluid magnetic sealing means.
Claim 3
Dependent Claim
76 words
In combination with a gearbox/transmission housing or the like containing a liquid lubricant and having a shaft extending from within; a ferrofluid magnetic sealing means interposed between the shaft and housing and encircling the shaft at the point of exit from the housing; and a pressurized air supply cavity spaced axially inward next to the said ferrofluid magnetic sealing means, thereby preventing the said internally contained liquid lubricant from contacting the said ferrofluid magnetic sealing means.
Claim 4
Dependent Claim
76 words
In combination with a gearbox/transmission housing or the like containing a liquid lubricant and having a shaft extending from within; a ferrofluid magnetic sealing means interposed between the shaft and housing and encircling the shaft at the point of exit from the housing; and a pressurized air supply cavity spaced axially inward next to the said ferrofluid magnetic sealing means, thereby preventing the said internally contained liquid lubricant from contacting the said ferrofluid magnetic sealing means.
Claim 5
Dependent Claim
91 words
In combination with a gearbox/transmission housing or the like containing a liquid lubricant and having a shaft extending from within a ferrofluid magnetic sealing means interposed between the shaft and housing and encircling the shaft at the point of exit from the housing; a pressurized air supply cavity spaced axially inward next to the said ferrofluid magnetic sealing means; and a controlled clearance air orifice spaced axially inward next to the pressurized air supply cavity, thereby preventing the said internally contained liquid lubricant from contacting the said ferrofluid magnetic sealing means.
Claim 6
Dependent Claim
91 words
In combination with a gearbox/transmission housing or the like containing a liquid lubricant and having a shaft extending from within a ferrofluid magnetic sealing means interposed between the shaft and housing and encircling the shaft at the point of exit from the housing; a pressurized air supply cavity spaced axially inward next to the said ferrofluid magnetic sealing means; and a controlled clearance air orifice spaced axially inward next to the pressurized air supply cavity, thereby preventing the said internally contained liquid lubricant from contacting the said ferrofluid magnetic sealing means.
Claim 7
Dependent Claim
51 words
A device as set forth in claim 3 wherein the pressurized air supply cavity comprises an air cavity spaced axially inward next to the ferrofluid magnetic sealing means, an air valve for supplying pressurized air into said air cavity, and a low pressure escape valve located in the said gearbox/transmission housing.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-11-18 | 1978-05-20 | 1978-11-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-11-18 | 1982-05-20 | 1982-11-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-11-18 | 1986-05-20 | 1986-11-19 | $7700.00 | Window Closed / Lapsed |