Patent US3220484A successfully refreshed from Google Patents.
US3220484A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Cooling fans
Assignee: Dowty Hydraulic Units Ltd
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Filing: 1964-03-30
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Granted: 1965-11-30
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Expires: 1984-03-30
Abstract
No abstract record available.
Inventors
- 👤 Arthur E H Elmer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 22:33
CPC Classifications
F; F04; F04D; F04D29/00; F04D29/26; F04D29/32; F04D29/34; F04D29/36; F04D29/362; F04D29/366; F01; F01P; F01P7/00; F01P7/02; F01P7/06
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
178 words
A COOLING FAN FOR USE IN COOLING A VARIABLE SPEED ENGINE, AND OPERABLE AUTOMATICALLY TO MAINTAIN THE VOLUME OF AIR PASSING THROUGH THE FAN SUBSTANTIALLY CONSTANT THROUGHOUT A LARGE PART AT LEAST OF THE OPERATIONAL SPEED RANGE OF THE FAN, SAID FAN COMPRISING IN COMBINATION: (A) A HUB MOUNTED FOR ROTATION BY SUCH ENGINE ABOUT A ROTATIONAL AXIS, AT A SPEED THAT VARIES IN ACCORDANCE WITH THE SPEED OF SUCH ENGINE, (B) BLADES MOUNTED UPON SAID HUB FOR BODILY ROTATION EACH ABOUT AN AXIS DIRECTED SUBSTANTIALLY RADIALLY OF THE ROTATIONAL AXIS, SUCH BLADE ROTATION BEING ARRANGED TO OCCUR AUTOMATICALLY FROM COARSE PITCH TOWARDS FINE PITCH WITH INCREASE IN ROTATIONAL SPEED OF THE FAN, UNDER THE INFLUENCE OF CENTRIFUGAL TWISTING MOMENTS ABOUT THE BLADES'' RADIALLY DIRECTED AXES, WHICH MOMENTS ARE INHERENT IN EACH BLADE DURING ROTATION OF THE FAN ABOUT ITS ROTATIONAL AXIS, AND (C) TORSION SPRINGS DIRECTED GENERALLY RADIALLY, AT LEAST ONE FOR EACH BLADE, OPPOSING SUCH CENTRIFUGAL TWISTING MOMENTS AND ACTIVE TO ROTATE THE BLADES BACK TOWARDS COARSE PITCH UPON DECREASE IN ROTATIONAL SPEED OF THE FAN.
Claim 2
Dependent Claim
178 words
A COOLING FAN FOR USE IN COOLING A VARIABLE SPEED ENGINE, AND OPERABLE AUTOMATICALLY TO MAINTAIN THE VOLUME OF AIR PASSING THROUGH THE FAN SUBSTANTIALLY CONSTANT THROUGHOUT A LARGE PART AT LEAST OF THE OPERATIONAL SPEED RANGE OF THE FAN, SAID FAN COMPRISING IN COMBINATION: (A) A HUB MOUNTED FOR ROTATION BY SUCH ENGINE ABOUT A ROTATIONAL AXIS, AT A SPEED THAT VARIES IN ACCORDANCE WITH THE SPEED OF SUCH ENGINE, (B) BLADES MOUNTED UPON SAID HUB FOR BODILY ROTATION EACH ABOUT AN AXIS DIRECTED SUBSTANTIALLY RADIALLY OF THE ROTATIONAL AXIS, SUCH BLADE ROTATION BEING ARRANGED TO OCCUR AUTOMATICALLY FROM COARSE PITCH TOWARDS FINE PITCH WITH INCREASE IN ROTATIONAL SPEED OF THE FAN, UNDER THE INFLUENCE OF CENTRIFUGAL TWISTING MOMENTS ABOUT THE BLADES'' RADIALLY DIRECTED AXES, WHICH MOMENTS ARE INHERENT IN EACH BLADE DURING ROTATION OF THE FAN ABOUT ITS ROTATIONAL AXIS, AND (C) TORSION SPRINGS DIRECTED GENERALLY RADIALLY, AT LEAST ONE FOR EACH BLADE, OPPOSING SUCH CENTRIFUGAL TWISTING MOMENTS AND ACTIVE TO ROTATE THE BLADES BACK TOWARDS COARSE PITCH UPON DECREASE IN ROTATIONAL SPEED OF THE FAN.
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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) | 1968-11-29 | 1969-05-31 | 1969-11-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1972-11-29 | 1973-05-31 | 1973-11-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1976-11-29 | 1977-05-31 | 1977-11-30 | $7700.00 | Window Closed / Lapsed |