US3758231A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Flexible fan
Assignee: Vernco Corp
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Filing: 1971-07-15
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Granted: 1973-09-11
•
Expires: 1991-07-15
Abstract
Abstract A fan which, because of the particular construction of its blades, will automatically ''''unload'''' by flexure of portions only of its blades as its speed of rotation is increased, whereby the volume of air moved by the fan does not increase proportionally as the speed of the fan increases. Each of the identical blades has a reverse twist and consists of a stiff leading region formed as a portion of a cone, a resiliently flexible trailing region formed as a portion of a cylinder, and an intermediate region formed as a continuation of the same cylinder and rectilinearly extending from an area near the trailing edge of the blade root to an area near the leading edge of the blade tip, the axis of the cylinder being parallel with the intermediate region. Ideally, the fan is an integral plastic molding and the difference in flexibility of the several regions is achieved by making the leading region uniformly thick, the trailing region uniformly thin and the intermediate region of increasing thickness as it progresses between the trailing region and the leading region. The reverse twist feature is obtained by having the pitch at the tip of each blade greater than the pitch at its root.
Inventors
- 👤 J Barnstead
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 21:33
CPC Classifications
F; F04; F04D; F04D29/00; F04D29/26; F04D29/32; F04D29/38; F04D29/382
Claims Analysis
Total Claims: 35
Claim 1
Independent Claim
103 words
A fan comprising a hub and a plurality of blades radiating therefrom, each of said blades having a tip pitch significantly exceeding its root pitch and each of said blades including a stiff leading region formed as a portion of a cone having its base adjacent said hub and its apex disposed radially outwardly from said hub and a flexible generally cylindrically formed trailing region, the leading edge of said trailing region and the trailing edge of said leading region extending from an area adjacent the trailing edge of the blade root to an area adjacent the lading edge of the blade tip.
Claim 2
Dependent Claim
103 words
A fan comprising a hub and a plurality of blades radiating therefrom, each of said blades having a tip pitch significantly exceeding its root pitch and each of said blades including a stiff leading region formed as a portion of a cone having its base adjacent said hub and its apex disposed radially outwardly from said hub and a flexible generally cylindrically formed trailing region, the leading edge of said trailing region and the trailing edge of said leading region extending from an area adjacent the trailing edge of the blade root to an area adjacent the lading edge of the blade tip.
Claim 3
Dependent Claim
33 words
The fan of claim 1 in which said cone base is a circle located in a plane which is perpendicular to that radius of said hub which includes the center of said circle.
Claim 4
Dependent Claim
40 words
The fan of claim 2 in which said cone base is a circle located in a plane which cuts the periphery of said hub and is perpendicular to that radius of said hub which includes the center of said circle.
Claim 5
Dependent Claim
26 words
The fan of claim 2 in which the axis of said cone inclines forwardly to intersect the leading edge of said blade near said blade tip.
Claim 6
Dependent Claim
26 words
The fan of claim 3 in which the axis of said cone inclines forwardly to intersect the leading edge of said blade near said blade tip.
Claim 7
Dependent Claim
35 words
The fan of claim 1 in which the leading edge of said trailing region is rectilinear and said cylinder is a right cylinder whose axis is parallel with said leading edge of said trailing region.
Claim 8
Dependent Claim
28 words
The fan of claim 1 in which there are five identical blades peripherally spaced about said hub at successive angular intervals of 58*, 83*, 68*, 68* and 83*.
Claim 9
Dependent Claim
146 words
A fan comprising a hub and a plurality of blades radiating therefrom, each of said blades being formed to have a stiff leading region providing a leading edge and a trailing edge, a flexible trailing region having a thickness significantly less than that of said leading region and a leading edge, and an intermediate region flaring in thickness from its trailing edge, where it merges with the leading edge of said trailing region, to its leading edge, where it merges with the trailing edge of said leading region, said intermediate region extending forwardly from an area adjacent the trailing edge of the blade root to an area adjacent the leading edge of the blade tip, said leading edge of said intermediate region intersecting the leading edge of said leading region and said trailing edge of said intermediate region intersecting the distal end edge of the blade.
Claim 10
Dependent Claim
146 words
A fan comprising a hub and a plurality of blades radiating therefrom, each of said blades being formed to have a stiff leading region providing a leading edge and a trailing edge, a flexible trailing region having a thickness significantly less than that of said leading region and a leading edge, and an intermediate region flaring in thickness from its trailing edge, where it merges with the leading edge of said trailing region, to its leading edge, where it merges with the trailing edge of said leading region, said intermediate region extending forwardly from an area adjacent the trailing edge of the blade root to an area adjacent the leading edge of the blade tip, said leading edge of said intermediate region intersecting the leading edge of said leading region and said trailing edge of said intermediate region intersecting the distal end edge of the blade.
Claim 11
Dependent Claim
20 words
The fan of claim 8 in which each of said blades has a tip pitch significantly exceeding its root pitch.
Claim 12
Dependent Claim
151 words
A fan comprising a hub and a plurality of blades radiating therefrom, each of said blades being formed to have a stiff leading region, a flexible trailing region having a thickness significantly less than that of said leading region, and an intermediate region flaring in thickness from its trailing edge, where it merges with the leading edge of said trailing region, to its leading edge, where it merges with the trailing edge of said leading region, said intermediate region extending from an area adjacent the trailing edge of the blade root to an area adjacent the leading edge of the blade tip,said leading region being formed as a portion of a cone having its base adjacent said hub and its apex disposed radially outwardly from said hub, and said trailing region being formed as a portion of a cylinder whose axis is parallel to the leading edge of said trailing region.
Claim 13
Dependent Claim
151 words
A fan comprising a hub and a plurality of blades radiating therefrom, each of said blades being formed to have a stiff leading region, a flexible trailing region having a thickness significantly less than that of said leading region, and an intermediate region flaring in thickness from its trailing edge, where it merges with the leading edge of said trailing region, to its leading edge, where it merges with the trailing edge of said leading region, said intermediate region extending from an area adjacent the trailing edge of the blade root to an area adjacent the leading edge of the blade tip,said leading region being formed as a portion of a cone having its base adjacent said hub and its apex disposed radially outwardly from said hub, and said trailing region being formed as a portion of a cylinder whose axis is parallel to the leading edge of said trailing region.
Claim 14
Dependent Claim
50 words
The fan of claim 10 in which said intermediate region is formed as a continuation of such cylinder, the leading edge of said intermediate region and the trailing edge of said leading region meeting along a line lying in a plane which is tangential to such cylinder and such cone.
Claim 15
Dependent Claim
20 words
The fan of claim 11 in which each of said blades has a tip pitch significantly exceeding its root pitch.
Claim 16
Dependent Claim
20 words
The fan of claim 10 in which each of said blades has a tip pitch significantly exceeding its root pitch.
Claim 17
Dependent Claim
42 words
The fan of claim 11 in which said leading region and trailing region, respectively, have uniform thicknesses and every longitudinal section of said intermediate region is bounded by parallel straight lines lying, respectively, in the inner and outer surfaces of such cylinder.
Claim 18
Dependent Claim
18 words
The fan of claim 8 in which the leading and trailing edges of said intermediate region are parallel.
Claim 19
Dependent Claim
18 words
The fan of claim 14 in which the leading and trailing edges of said intermediate region are parallel.
Claim 20
Dependent Claim
20 words
The fan of claim 16 in which each of said blades has a tip pitch significantly exceeding its root pitch.
Claim 21
Dependent Claim
124 words
A molded plastic fan comprising a hub and a plurality of substantially identical blades radiating therefrom at non-uniform peripheral spacings, each of said blades having a tip pitch significantly exeeding its root pitch and each of said blades comprising a stiff leading region of uniform thickness and formed as a portion of a cone, a trailing region of uniform thickness significantly less than that of said leading region and formed as a portion of a right cylinder, and an intermediate region formed as a continuation of said cylinder and flaring in thickness from its rectilinear trailing edge, where it merges with the leading edge of said trailing region, to its rectilinear leading edge, where it tangentially meets the trailing edge of said leading region.
Claim 22
Dependent Claim
124 words
A molded plastic fan comprising a hub and a plurality of substantially identical blades radiating therefrom at non-uniform peripheral spacings, each of said blades having a tip pitch significantly exeeding its root pitch and each of said blades comprising a stiff leading region of uniform thickness and formed as a portion of a cone, a trailing region of uniform thickness significantly less than that of said leading region and formed as a portion of a right cylinder, and an intermediate region formed as a continuation of said cylinder and flaring in thickness from its rectilinear trailing edge, where it merges with the leading edge of said trailing region, to its rectilinear leading edge, where it tangentially meets the trailing edge of said leading region.
Claim 23
Dependent Claim
37 words
The fan of claim 18 in which said intermediate region extends from an area adjacent the trailing edge of the root of the blade to an area adjacent the leading edge of the tip of the blade.
Claim 24
Dependent Claim
31 words
The fan of claim 18 in which every longitudinal section of said intermediate region is bounded by parallel straight lines lying, respectively, in the inner and outeR surfaces of such cylinder.
Claim 25
Dependent Claim
16 words
The fan of claim 19 in which said rectilinear edges of said intermediate region are parallel.
Claim 26
Dependent Claim
24 words
The fan of claim 21 in which the distal ends of said rectilinear edges are oppositely offset from the extreme tip of said blade.
Claim 27
Dependent Claim
94 words
A fan blade having a stiff leading region providing a leading edge, and a flexible trailing region merging in a generally rectilinear intermediate region extending forwardly from an area adjacent the trailing edge of the root of said blade to an area adjacent the leading edge of the tip of said blade , said intermediate region having a rectilinear leading edge intersecting the leading edge of said leading region and a rectilinear trailing edge intersecting the distal end edge of said blade, and said blade having a tip pitch significantly exceeding its root pitch.
Claim 28
Dependent Claim
94 words
A fan blade having a stiff leading region providing a leading edge, and a flexible trailing region merging in a generally rectilinear intermediate region extending forwardly from an area adjacent the trailing edge of the root of said blade to an area adjacent the leading edge of the tip of said blade , said intermediate region having a rectilinear leading edge intersecting the leading edge of said leading region and a rectilinear trailing edge intersecting the distal end edge of said blade, and said blade having a tip pitch significantly exceeding its root pitch.
Claim 29
Dependent Claim
87 words
A fan blade having a stiff leading region and a flexible trailing region merging in a generally rectilinear region extending from an area adjacent the trailing edge of the root of said blade to an area adjacent the leading edge of the tip of said blade, said leading region being formed as a portion of a cone with its base near the root of said blade and its apex near the tip of said blade, and said trailing region being formed as a portion of a cylinder.
Claim 30
Dependent Claim
87 words
A fan blade having a stiff leading region and a flexible trailing region merging in a generally rectilinear region extending from an area adjacent the trailing edge of the root of said blade to an area adjacent the leading edge of the tip of said blade, said leading region being formed as a portion of a cone with its base near the root of said blade and its apex near the tip of said blade, and said trailing region being formed as a portion of a cylinder.
Claim 31
Dependent Claim
22 words
The fan blade of claim 24 in which said cylinder is a right cylinder with its axis parallel with said rectilinear region.
Claim 32
Dependent Claim
106 words
A molded plastic fan blade having a reverse twist whereby its pitch at its tip significantly exceeds its pitch at its root, said blade comprising a stiff leading region formed as a portion of a cone, a flexible trailing region having a thickness significantly less than that of said leading region and formed as a portion of a cylinder, and an intermediate region formed as a continuation of said cylinder and flaring in thickness from its rectilinear trailing edge, where it merges with the leading edge of said trailing region, to its rectilinear leading edge, where it tangentially meets the trailing edge of said leading region.
Claim 33
Dependent Claim
106 words
A molded plastic fan blade having a reverse twist whereby its pitch at its tip significantly exceeds its pitch at its root, said blade comprising a stiff leading region formed as a portion of a cone, a flexible trailing region having a thickness significantly less than that of said leading region and formed as a portion of a cylinder, and an intermediate region formed as a continuation of said cylinder and flaring in thickness from its rectilinear trailing edge, where it merges with the leading edge of said trailing region, to its rectilinear leading edge, where it tangentially meets the trailing edge of said leading region.
Claim 34
Dependent Claim
33 words
The blade of claim 26 in which said intermediate region extends from an area adjacent the trailing edge of the blade root to an area adjacent the leading edge of the blade tip.
Claim 35
Dependent Claim
20 words
The blade of claim 27 wherein said cylinder is a right cylinder whose axis is parallel with said rectilinear edges.
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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) | 1976-09-10 | 1977-03-12 | 1977-09-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-09-10 | 1981-03-12 | 1981-09-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-09-10 | 1985-03-12 | 1985-09-11 | $7700.00 | Window Closed / Lapsed |