Axial flow fan improvements

Abstract

An energy efficient and compact axial fan with a housing comprising a fan assembly comprising a drive motor and a propeller coupled thereto. The inlet opening and / or the outlet opening of the fan housing are provided with a shutter assembly positioned adjacent the propeller and having a plurality aerodynamically shaped pivoted louvers working in tandem for less air obstruction and noise. The propeller comprises a plurality of radial blades comprising means for straitening the air flow and reducing the vortex flow of the propeller thereby permitting the shutter to be mounted adjacent the propeller to lessen the dept of the fan housing for making the fan more compact.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The invention disclosed herein relates generally to axial flow fans improvements and, more particularly to axial flow fans having a shutter operated by a centrifugal mechanism for maintaining a controlled environment in buildings such as poultry houses, greenhouses, steel-plants, foundries, etc. [0003] 2. Description of the Related Art [0004] Axial flow fans are used to move high volume of air at low static pressure. An application in which they are beneficially used involves the ventilation of poultry house buildings which often are shaped like a tunnel. Intensive rearing of birds (typically more than 10 000) imposes severe demands on the fans which are provided for removing moisture, heat, carbon dioxide and other contaminants from said buildings. [0005] Hot summer days often cause indoor conditions to become much hotter than desired, temperatures above 25 degree Celsius have an adverse effect on production of sai...

AI Technical Summary

Benefits of technology

[0026] The present invention relates to an axial flow fan that is particularly quiet in operation and effectively overcomes the prior art drawbacks.

[0032] The third embodiment of the invention provides a fan with a compact square shaped housing and a shutter assembly comprising a plurality of pair of vertical mounted vanes vertically extending across the outlet opening of the fan and having leading edges connected each other with a hinge. The vanes work in tandem and are operated by a centrifugal mechanism via a roller bearing connection. A propeller is provided with a plurality of airfoil shaped blades comprising an outer circular band bolted to the tip portions of said blades to lessen the known vortices, vibrations and noise. The fan housing is very compact and comprises an intake bell mouth having a round portion mounted coaxially to the outer circular band of said propeller for guiding smoothly the ambient air for best efficiency and low noise. The fan further comprises a discharge duct for protecting the shutter assembly and permitting moisture to be evacuated away from the fan housing.

[0036] A further object is to provide a maintenance free axial flow fan suitable to work at higher static pressure to move efficiently, quietly and consistently large quantities of air.

[0037] Another object of this invention is to provide an axial flow fan that is strong, compact and durable, comprising few parts that can be quickly assemble.

Problems solved by technology

Intensive rearing of birds (typically more than 10 000) imposes severe demands on the fans which are provided for removing moisture, heat, carbon dioxide and other contaminants from said buildings.

Hot summer days often cause indoor conditions to become much hotter than desired, temperatures above 25 degree Celsius have an adverse effect on production of said birds.

As a result, when wind blows against the fans, the air flow decreases substantially and will not be sufficient to cool the birds which will suffer of heat stress.

However, the solution is not satisfactory because increases the capital cost and the operating cost due to an increase of energy consumption.

As it can be imagined, the large number of vanes constitutes an obstruction to air flow and raise the cost of the fan, which is also increased by the cost of labor required to assemble the large quantity of vanes and elements connecting them.

Any reduction in needed air flow can reduce bird performance and increases mortalities of the birds.

As a result, the fans are bulkier and heavier and the manufacturing and shipping costs are significantly higher.

The poultry house fans may operate continuously generating also undesirable noise and vibrations.

Vibrations and excessive noise of the fans mainly are caused by the air pushed by the propeller and passing across the vanes which oscillate.

Another important source of noise is caused by the blades of the propeller which during its rotational movement over obstacles produce a pressure variation on the obstacle which results in noise emission.

Since the function of the propeller blades is to move air in a direction parallel to a rotational axis, velocities imparted in other directions represent degradation in efficiency, increase of the noise and cost to operate the fan.

In particular, the air flow around the tip region of said propeller blades creates a very noisy and strong vortex trailing downstream from the blade tips.

Heretofore, it was necessary to ship a large amount of “air” in the assembled fans at a cost that became significant especially with overseas shipments.

Another problem encountered with axial flow fans used in poultry house buildings includes the drive belt.

Over time, a typical V-belt will eventually wear and the tension transmitted by the belt will vary causing slippage and reduction of fan air flow.

The above patents have been fully described in my referred patent and patent application and show propeller fans comprising a centrifugal mechanism designed to operate positively the shutter vanes which are made of thin metal providing relatively poor insulating qualities, said vanes lack positive seals which do not permit them to be used effectively in severe and cold climate areas.

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