US4142844A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Fan blade assemblies for box fans
Assignee: Allware Agencies Ltd
•
Filing: 1977-05-31
•
Granted: 1979-03-06
•
Expires: 1997-05-31
Abstract
Abstract A box fan comprising a box-like structure having front and rear openings interconnected to form a duct passing through said structure, said duct containing an electric motor and a large axial depth wide-bladed fan blade assembly operable by the motor to rotate about an axis of rotation, which fan blade assembly is so located that the center of gravity of said fan blade assembly is located near the rear opening, wherein the fan blade assembly has a plurality of blades each of which has a shape in a plane normal to the axis of rotation, which shape comprises a neck connecting the blade to a hub defining the center of the fan blade assembly, a slightly convex leading edge extending from said neck, a convex outermost edge, a slightly convex trailing edge and a chin portion connecting the trailing edge to the neck, said trailing edge being heavily set near said chin portion and being decreasingly heavily set as the outermost edge is approached along said trailing edge.
Inventors
- 👤 Edward H. Brattstrom
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 04:00
CPC Classifications
F; F04; F04D; F04D25/00; F04D25/02; F04D25/08; F04D25/12; F04D29/00; F04D29/26; F04D29/32; F04D29/38; F04D29/384; Y; Y10; Y10S; Y10S416/00; Y10S416/03
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
167 words
A box fan comprising a box-like structure having a front and rear opening interconnected to form a duct passing through said structure said duct containing an electric motor and a large axial depth wide-bladed fan blade assembly operable by the motor to rotate about an axis of rotation, which fan blade assembly is so located that the centre of gravity of said fan blade assembly is located near the rear opening, wherein the fan blade assembly has a plurality of blades each of which has a shape in a plane normal to the axis of rotation, which shape comprises a neck connecting the blade to a hub defining the centre of the assembly, a slightly convex leading edge extending from said neck, a convex outermost edge, a slightly convex trailing edge and a chin portion connecting the trailing edge to the neck, said trailing edge being heavily set near said chin portion and being decreasingly heavily set as the outermost edge is approached along said trailing edge.
Claim 2
Dependent Claim
167 words
A box fan comprising a box-like structure having a front and rear opening interconnected to form a duct passing through said structure said duct containing an electric motor and a large axial depth wide-bladed fan blade assembly operable by the motor to rotate about an axis of rotation, which fan blade assembly is so located that the centre of gravity of said fan blade assembly is located near the rear opening, wherein the fan blade assembly has a plurality of blades each of which has a shape in a plane normal to the axis of rotation, which shape comprises a neck connecting the blade to a hub defining the centre of the assembly, a slightly convex leading edge extending from said neck, a convex outermost edge, a slightly convex trailing edge and a chin portion connecting the trailing edge to the neck, said trailing edge being heavily set near said chin portion and being decreasingly heavily set as the outermost edge is approached along said trailing edge.
Claim 3
Dependent Claim
22 words
A box fan according to claim 1, wherein each blade has an angle of attack in the range between 20° and 30°.
Claim 4
Dependent Claim
26 words
A box fan according to claim 1, wherein the trailing edge of each blade has a maximum set lying in the range between 30° and 45°.
Claim 5
Dependent Claim
30 words
A box fan according to claim 1, wherein said shape of each blade is further defined by convex connecting edges connecting said leading and trailing edges with said outermost edge.
Claim 6
Dependent Claim
50 words
A box fan according to claim 1, wherein the leading and trailing edges are defined by radii of curvature which approximate the radius of the fan blade assembly and the outermost edge is defined by a radius of curvature which is approximately half the radius of said fan blade assembly.
Claim 7
Dependent Claim
34 words
A box fan according to claim 4, wherein the connecting edges are defined by radii of curvature which lie in the range of one-fifth to one-third of the radius of said fan blade assembly.
Claim 8
Dependent Claim
22 words
A box fan according to claim 1, wherein the axis of rotation is contiguous with the axis of symmetry of said duct.
Claim 9
Dependent Claim
133 words
A box fan according to claim 7, wherein the rear opening of said duct defines a circle having a radius which lies in the range from 1.05R to 1.20R, said circle being in a plane normal to the axis of symmetry of the duct, the fan blade assembly is so located that its centre of gravity is situated on said axis at a point which lies in the range between a point inside said duct 10 mm. from said plane and a point outside said duct 2.5 mm. from said plane and the leading, trailing and outermost edges of said blades have mean radii of curvature which lie in the range from 0.7R to infinity, 0.7R to infinity and 0.4R to 0.6R respectively, where R is the radius of the fan blade assembly.
Claim 10
Dependent Claim
111 words
A box fan according to claim 7, wherein the rear opening of said duct defines a circle having a radius which lies in the range from 1.05R to 1.20R, said circle being in a plane normal to the axis of symmetry of the duct, the centre of gravity of the fan blade assembly is located on said axis at a point inside said duct 2.5 mm from said plane and the leading, trailing and outermost edges of said blades have mean radii of curvature which lie in the range from 0.7R to infinity, 0.7R to infinity and 0.4R to 0.6R respectively, where R is the radius of the fan blade assembly.
Claim 11
Dependent Claim
129 words
A box fan comprising a box-like structure having a front and rear opening interconnected to form a duct passing through said structure, said duct containing an electric motor and a large axial depth wide-bladed fan blade assembly operable by the motor to rotate about an axis of rotation wherein, the rear opening, the duct and the blades comprising the fan blade assembly include means for causing the air flow to approach a maximum and noise generation to approach a minimum including means for positioning the fan blade assembly with respect to the duct so that the centre of gravity of the fan blade is situated between a point 10 mm in from a plane defining the rear opening of the duct and a point 2.5 mm outside said plane.
Claim 12
Dependent Claim
129 words
A box fan comprising a box-like structure having a front and rear opening interconnected to form a duct passing through said structure, said duct containing an electric motor and a large axial depth wide-bladed fan blade assembly operable by the motor to rotate about an axis of rotation wherein, the rear opening, the duct and the blades comprising the fan blade assembly include means for causing the air flow to approach a maximum and noise generation to approach a minimum including means for positioning the fan blade assembly with respect to the duct so that the centre of gravity of the fan blade is situated between a point 10 mm in from a plane defining the rear opening of the duct and a point 2.5 mm outside said plane.
References Cited (Backward Citations)
US1506937A
Cited
US1775863A
Cited
US2097389A
Cited
US2011821A
Cited
US1991095A
Cited
US2023111A
Cited
US2212041A
Cited
US2240597A
Cited
US2460902A
Cited
US2578806A
Cited
AU459701B2
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-03-05 | 1982-09-04 | 1983-03-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-03-05 | 1986-09-04 | 1987-03-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-03-05 | 1990-09-04 | 1991-03-06 | $7700.00 | Window Closed / Lapsed |