Fluid reaction surfaces (i.e. – impellers) – Specific blade structure – Radial flow devices
Reexamination Certificate
2001-02-09
2002-06-11
Look, Edward K. (Department: 3745)
Fluid reaction surfaces (i.e., impellers)
Specific blade structure
Radial flow devices
Reexamination Certificate
active
06402475
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a fan blade, and more particularly to a blade for a ceiling fan.
2. Description of Related Art
With reference to
FIG. 7
, a conventional blade (
30
) for a ceiling fan in accordance with the prior art is made of multiple wooden lamina (
301
). The lamina (
301
) are placed up one over another, bonded and pressed into an integral piece with a suitable thickness. The blade (
30
) includes multiple ridges (
302
) longitudinally formed on one face of the blade (
30
) and multiple corresponding grooves (
303
) defined in the other face of the blade (
30
).
The conventional blade of a ceiling fan has several disadvantages.
1. The fabrication process is complex, and the cost of the conventional blade is higher because the conventional blade for a ceiling fan is made of multiple wooden lamina that need to be pressed to form the ridges and the grooves.
2. The conventional blade for a ceiling fan is heavy so the load on the ceiling fan motor is significant.
3. The drag on the conventional blade is great. The ridges will cause greater drag and waste power when the ceiling fan is operated.
The present invention has arisen to mitigate and/or obviate the disadvantages of the conventional blade of a ceiling fan.
SUMMARY OF THE INVENTION
The main objective of the present invention is to provide an improved blade for a ceiling fan. The blade of the present invention includes at least one raised portion formed on the surface of the blade with a hollow chamber in the raised portion. The raised portion will reduce the windage resistance when the air passes over the blade because the blade has a smooth surface due the raised portion. The hollow chamber in the raised portion provides flexibility to the blade to lengthen the useful life of the blade.
Further benefits and advantages of the present invention will become apparent after a careful reading of the detailed description with appropriate reference to the accompanying drawings.
REFERENCES:
patent: 2392671 (1946-01-01), Husted
Look Edward K.
McAleenan James M
Rosenberg , Klein & Lee
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