Fluid reaction surfaces (i.e. – impellers) – Perimetric blading extending axially between annular members
Reexamination Certificate
1999-06-24
2001-03-20
Look, Edward K. (Department: 3745)
Fluid reaction surfaces (i.e., impellers)
Perimetric blading extending axially between annular members
C416S195000, C416S24100B
Reexamination Certificate
active
06203278
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This application relates to centrifugal blower wheels such as used in air moving equipment, including furnaces, air conditioners, and HVAC equipment in general. In particular, the present application is directed to disc type centrifugal blower wheels having a center disc and a plurality of blades, each blade having a notch frictionally engaged over the edge of the center disc.
2. Related Prior Art
Conventional type blower wheels are typically constructed with a pair of disc shaped support plates formed with a conical shape and located in abutting relation with each other such that the outer edges of the plates are joined together and the central areas of the plates are in spaced relation to each other. Each plate includes a hub joined thereto whereby the plates are mounted to a common drive shaft. The plates and hubs define a center disc assembly which is driven in rotation by the common shaft. A blade assembly comprising a plurality of circumferentially spaced blades are arranged around and supported on the outer peripheral edge of the disc assembly. In a known construction, each of the blades is provided with a notch located centrally between either end of the blade and located at an inner edge of the blade. A peripheral edge of each of the plates is positioned in frictional engagement with an adjacent notch edge, and the frictional engagement between the center disc assembly and the blade notches define a connection between the blade assembly and the center disc assembly such that rotation of the center disc assembly causes rotation of the blade assembly. Examples of such blower wheel constructions are shown in U.S. Pat. Nos. 3,423,012 and 4,515,527.
While this construction has been used for a number of years with satisfactory results, there is an ongoing need for an improved connection between the center disc assembly and the blade assembly. In short, there is a need for the formation of a positive connection between the two assemblies for preventing slippage of the blade assembly relative to the disc assembly in response to torque applied to the drive shaft supporting the center disc assembly.
SUMMARY OF THE INVENTION
The present invention is directed to an improvement in centrifugal blower wheels which increases the frictional forces preventing relative movement between a center disc assembly of the blower wheel and a blade assembly of the blower wheel.
The centrifugal blower wheel of the present invention includes a circular center disc having a central shaft mounting structure for supporting the center disc on a driving shaft. A plurality of elongated blades are arranged parallel to and in circumferentially spaced relation to each other around the circumference of the center disc. Each of the blades includes a notch for receiving and frictionally engaging the peripheral edge of the center disc, and the peripheral edge of the center disc includes a distinct roughened surfaced for increasing frictional forces between the center disc and the blades.
In a further aspect of the invention, the roughened surface comprises distinct raised surfaces extending outwardly from an axially facing surface of the center disc, parallel to a direction of elongation of the blades.
The center disc comprises two plates joined together wherein outer peripheral edges of the joined plates are bent away from each other to thereby define a dovetail configuration around the periphery of the disc. Each of the blades is formed with a dovetail shaped cutout area or notch for receiving the dovetail configuration of the outer edge of the disc. In the preferred embodiment of the invention, axially facing surfaces of each of the outer peripheral edges of the discs, facing the edges of the notches in the blades, are formed with a distinct roughened surface for engaging the notch edges and preventing relative slippage between the center disc assembly and the blade assembly.
It is therefore and object of the present invention to provide an improved center disc assembly for a centrifugal blower wheel for providing positive engagement with the blades of a blade assembly to prevent slippage.
It is a further object of the invention to provide the center disc assembly with a roughened peripheral edge surface which facilitates engagement between the peripheral edge of the disc and notches formed in the blades of the blade assembly.
Other objects and advantages of the invention will be apparent from the following description and the accompanying drawings.
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Biebel & French
Lau Industries, Inc.
Look Edward K.
Nguyen Ninh
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