Fluid reaction surfaces (i.e. – impellers) – Combined or convertible – Hub lubrication or seal
Reexamination Certificate
1998-04-27
2001-04-10
Verdier, Christopher (Department: 3745)
Fluid reaction surfaces (i.e., impellers)
Combined or convertible
Hub lubrication or seal
C416S24700A
Reexamination Certificate
active
06213718
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is generally directed to a fan. Particularly, the present invention is directed to an air circulation fan having a shroud for enhancing fan performance.
2. Description of the Related Art
Electric fans for circulating air are widely used in commercial and industrial environments. For example, air circulation fans are commonly located at each work station in factories, such as automobile plants. In the past, operation of air circulation fans has generated a considerable amount of noise. The primary source of noise during the operation of such fans is the interaction of the tip region of each blade with moving air generated by operation of the fan. Reduction in noise levels caused by the operation of an air circulation fan is therefore desired, particularly in those environments in which a large number of such fans are utilized.
Air circulation fans have previously not been used in agricultural settings for a variety of reasons. Most notably, in agricultural settings, such as poultry barns, it is desirable to use fans which can disperse unclean air at high flow rates. Conventional air circulation fans, which utilize traditional front and rear fan guard members in the form of a grille, do not produce these desired results, and have thus been unsatisfactory for use in a poultry barn. Accordingly, box-type fans, which have a closed structure and a venturi surrounding the periphery of the fan propeller, have been widely used in agricultural settings. Box-type fans operating under adverse static pressures can produce a flow of air having a cfm valve. A distinct disadvantage, however, is that the inlet flow field pattern is purely axial which results in stagnant flow regions in areas upstream and adjacent to the fan itself. The need exists for a fan which enhances air circulation without significantly increasing the cost of the fan and noise levels as well as the complexity of its manufacture. Additionally, the need exists for an air circulator fan which is useful in an agricultural setting, such as a poultry barn. The present invention meets these needs while overcoming the drawbacks of the prior art.
SUMMARY OF THE INVENTION
An air circulation fan has front and rear fan guard members. Each front and rear fan guard member has a plurality of spaced apart ribs extending radially outward from a generally central location. A conventional grill is secured over the ribs to form a concave dish-shaped member. An outer peripheral rim is secured along the outer periphery of each guard member to an outer end portion of each radially extending rib.
Each fan guard member preferably defines a central opening. The central opening in the front fan guard member accepts a name plate, while the central opening in the rear fan guard member is preferably slightly larger than the opening in the front fan guard member, and receives a portion of an electrical motor. The motor is secured by fasteners to the rear fan guard member, and any conventional propeller or blade arrangement is attached to the electrical motor.
A plurality of selected ribs of the ribs on the front fan guard member are each bent at an outer end to form a hook. Each hook overlaps and partially surrounds the outer peripheral rim of the rear fan guard member, thereby securing two fan guard members together. When the front fan guard member is secured to the rear fan guard member, the radially extending ribs of the respective guard members are offset from each other, to prevent the radially extending ribs of the rear fan guard member from interfering with the hook portions. It will be understood that hook members could, alternatively, or additionally, be formed on outer ends of selected ribs on the rear fan guard member.
In accordance with the principles of the invention, a removable shroud is positioned about an outer peripheral portion of the front fan guard member. The shroud forms an annular ring having a central, air discharge opening.
In one embodiment, the removable shroud is formed of an integral piece of stretchable material, such as an elastomeric material. In such an embodiment, the removable shroud forms an elastomeric band which releasably engages about an outer peripheral portion of the front fan guard member. Particularly, the shroud is stretched, and thus expands, to place it into engagement with the front fan guard member. The stretchable shroud thus securely adapts to the contour of the outer peripheral portion of the front fan guard member.
In an alternate embodiment, the removable shroud is formed of a plurality of identical shroud portions. Each shroud portion has at least one clip for clipping to the front fan guard member. In each embodiment, the central opening of the shroud preferably has a diameter which is slightly less than the diameter of an imaginary circle caused by a line of rotary movement of the outer tips of the blades of the propeller.
In operation of the fan, with the removable shroud secured to the outer peripheral portion of the front fan guard member, the noise generated by the fan is greatly reduced when compared to operation of the fan with the shroud removed. Additionally, inclusion of the shroud on the fan allows the air circulator to operate under a static pressure differential.
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Hill D. Lee
Massali Hamid
Emerson Electric Co.
Hovey Williams Timmons & Collins
Verdier Christopher
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