US3773435A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Flexible blade fan
Assignee: Brookside Corp
•
Filing: 1971-07-23
•
Granted: 1973-11-20
•
Expires: 1991-07-23
Abstract
Abstract Disclosed is a flexible blade fan structure in which the flexible fan blades are stabilized by an overlying lamination formed to provide fingers curved and of tapering configuration. In the dynamic condition, that is, when the blade is rotated and undergoing flexure, the radius of curvature of the fingers is less than the radius of transverse curvature of the fan blade so that the fingers act as beams of uniform strength (or constant stress beams) point loaded by deflection of the fan blade under load. The rubbing between the contiguous surfaces of the blades and laminations, in the dynamic condition, serves to damp vibratory forces.
Inventors
- 👤 J Wooden
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 01:08
CPC Classifications
F; F04; F04D; F04D29/00; F04D29/26; F04D29/32; F04D29/38; F04D29/382
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
150 words
A fan structure including a spider having arms extending radially outward from a central hub portion and a transversely curved flexible fan blade attached to each of said arms said fan blades each having a flexible lamination overlying the convex surface of said fan blade and formed to provide multiple extending cantilever mounted fingers of tapered configuration providing uniform stress along their length when loaded at their free end, said fingers being curved along their length with their free ends engaging said convex fan blade surface, whereby transverse flexure of the blade during rotation of the fan structure applies a point loading to said lamination fingers, said fingers reacting as constant stress beams to control blade flexure over a wide range of blade flexure values with minimum mass, and the frictional rubbing action of said fingers on said blades as blade flexure occurs serving to damp vibration of the blades.
Claim 2
Dependent Claim
150 words
A fan structure including a spider having arms extending radially outward from a central hub portion and a transversely curved flexible fan blade attached to each of said arms said fan blades each having a flexible lamination overlying the convex surface of said fan blade and formed to provide multiple extending cantilever mounted fingers of tapered configuration providing uniform stress along their length when loaded at their free end, said fingers being curved along their length with their free ends engaging said convex fan blade surface, whereby transverse flexure of the blade during rotation of the fan structure applies a point loading to said lamination fingers, said fingers reacting as constant stress beams to control blade flexure over a wide range of blade flexure values with minimum mass, and the frictional rubbing action of said fingers on said blades as blade flexure occurs serving to damp vibration of the blades.
Claim 3
Dependent Claim
26 words
A fan structure as claimed in claim 1 in which said lamination is generally U-shaped in cross-section and embraces the leading edge of the fan blade.
Claim 4
Dependent Claim
33 words
A fan structure as claimed in claim 1 in which an elastic cushioning layer is disposed between the adjacent surfaces of said blade and lamination to enhance the frictional damping of blade vibration.
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) | 1976-11-19 | 1977-05-21 | 1977-11-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-11-19 | 1981-05-21 | 1981-11-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-11-19 | 1985-05-21 | 1985-11-20 | $7700.00 | Window Closed / Lapsed |