Patent US4003671A successfully refreshed from Google Patents.
US4003671A
Expired / Lapsed
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Method and means to prevent cavitation erosion in propeller ducts
Assignee: NORGES SKIPSFORSKNINGSINSTITUTT
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Filing: 1974-11-26
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Granted: 1977-01-18
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Expires: 1994-11-26
Abstract
Abstract The invention relates to a method and a means to prevent cavitation and/or erosion in propeller ducts, and the invention is generally characterized in that air is supplied to the so-called "gap cavities" which are formed at the blade extremities or tips and between blade tips and the duct surface.
Inventors
- 👤 Erling Huse
- 👤 Knut Minsaas
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 22:30
CPC Classifications
B; B63; B63H; B63H1/00; B63H1/02; B63H1/12; B63H1/14; B63H1/18; B63H5/00; B63H5/07; B63H5/14; Y; Y10; Y10S; Y10S415/00; Y10S415/914
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
63 words
A method for preventing erosion of a ship propeller duct, wherein propeller blade tips rotate adjacent a surface of said duct with the resultant formation of gap cavities therebetween, said method comprising: supplying air to said gap cavities between said propeller blade tips and said duct surface, by passing air through at least one tube fixed to the inner surface of said duct.
Claim 2
Independent Claim
63 words
A method for preventing erosion of a ship propeller duct, wherein propeller blade tips rotate adjacent a surface of said duct with the resultant formation of gap cavities therebetween, said method comprising: supplying air to said gap cavities between said propeller blade tips and said duct surface, by passing air through at least one tube fixed to the inner surface of said duct.
Claim 3
Dependent Claim
26 words
A method as claimed in claim 1, wherein said air is supplied to a limited area of the upper half of the circumference of said duct.
Claim 4
Dependent Claim
17 words
A method as claimed in claim 2, wherein said air is supplied through a plurality of tubes.
Claim 5
Dependent Claim
16 words
A method as claimed in claim 3, wherein said tubes have outlets in said gap cavities.
Claim 6
Dependent Claim
17 words
A method as claimed in claim 3, wherein said tubes have outlets upstream of said gap cavities.
Claim 7
Dependent Claim
77 words
In a ship structure including a propeller duct and a propeller rotatably mounted therein, said propeller having blade tips rotating adjacent a surface of said duct with the resultant formation of gap cavities therebetween, the improvement comprising: means for preventing erosion of said duct surface, said means comprising at least one tube means fixed to the inner surface of said duct for supplying air to said gap cavities between said propeller blade tips and said duct surface.
Claim 8
Dependent Claim
77 words
In a ship structure including a propeller duct and a propeller rotatably mounted therein, said propeller having blade tips rotating adjacent a surface of said duct with the resultant formation of gap cavities therebetween, the improvement comprising: means for preventing erosion of said duct surface, said means comprising at least one tube means fixed to the inner surface of said duct for supplying air to said gap cavities between said propeller blade tips and said duct surface.
Claim 9
Dependent Claim
26 words
The improvement claimed in claim 6, wherein said tube means is positioned adjacent a limited area of the upper half of the circumference of said duct.
Claim 10
Dependent Claim
15 words
The improvement claimed in claim 7, wherein said tube means comprises a plurality of tube.
Claim 11
Dependent Claim
15 words
The improvement claimed in claim 8, wherein said tubes have outlets in said gap cavities.
Claim 12
Dependent Claim
16 words
The improvement claimed in claim 8, wherein said tubes have outlets upstream of said gap cavities.
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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) | 1980-01-18 | 1980-07-19 | 1981-01-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-01-18 | 1984-07-19 | 1985-01-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-01-18 | 1988-07-19 | 1989-01-18 | $7700.00 | Window Closed / Lapsed |