Low noise fan
AssigneeBolt Beranek and Newman Inc.
InventorLeslie M. Gray
Life of this patent
Estimating the term…
Abstract
A low noise, axial flow fan particularly suited for use in a turbulent air flow such as the flow exiting an automobile radiator has a band that is secured to the outer ends of the fan blades. The blades are highly forwardly skewed and have an increasing blade angle as a function of blade radius over at least the outer portions of the blade. Each blade is secured to the band along its full width. In the preferred form, the band has a cross-sectional shape that acts as a nozzle to accelerate the airflow through the fan, each blade has a cambered, airfoil cross-section, and the entire fan is formed of an injection molded plastic as a single, integral structure.
Claims20
A fan particularly suited to low noise operation in a turbulent air flow comprising
- a hub having a center of rotation for the fan that is aligned in a first direction,
- a generally circular band concentric with and surrounding the hub, said band extending generally in the first direction, and
- a plurality of fan blades each secured between said hub and said band,
- each of said blades:
- (i) being highly forwardly skewed;
- (ii) having an increasing blade angle as a function of blade radius over at least the portion of said blade adjacent said band;
- and
- (iii) being secured to said band continuously along its width.
A fan system adapted for low noise operation that creates an axial airflow in a first direction from a region of turbulent air associated with a radiator comprising,
- a hub having a center of rotation for the fan that is generally aligned with said first direction,
- a generally circular band concentric with and surrounding the hub, said band extending generally in the first direction and having a cross-sectional shape that produces an acceleration of the airflow through the band in the first direction,
- a plurality of fan blades each secured between said hub and said band,
- each of said blades:
- (i) being highly forwardly skewed;
- (ii) having an increasing attack angle as a function of blade radius over at least the portion of said blade adjacent said band;
- and
- (iii) being secured to said band continuously along its width, and
- means for preventing the recirculation of air from the high pressure side of said fan to the low pressure side.
An axial flow automotive fan adapted for low noise operation in a turbulent air flow exiting a radiator in a first direction comprising,
- a hub having a center of rotation for the fan that is generally aligned with said first direction,
- a generally circular band concentric with and surrounding the hub, said band extending generally in the first direction and having a cross-sectional shape that produces an acceleration of the airflow through the band in the first direction,
- a plurality of fan blades each secured between said hub and said band,
- each of said blades:
- (i) being highly forwardly skewed with the centerline of the top half of each blade adjacent said band being angularly spaced ahead of the centerline of the root of the blade adjacent said hub by an angle that is at least half that of the angular spacing between adjacent blades,
- (ii) having an increasing blade angle as a function of blade radius over at least the portion of said blade adjacent said band;
- (iii) being secured to said band continuously along its width, and
- (iv) having a cambered, airfoil configuration.
Dependencies are inferred from the claim text.