Abstract:
A blower wheel comprising a centerdisk comprising a conical portion ( 16 ), a planar portion ( 160 ) for receiving a hub ( 7 ), and an arcuate portion ( 15 ) intermediate the conical portion and an outer portion ( 14 ), a plurality of blades ( 2 ) connected to the outer portion, the blades further connected to a ring ( 3 ), and a hub connected to the planar portion, the hub comprising a fastener ( 13 ) for attaching the centerdisk to a shaft ( 200 ).

Description:
FIELD OF THE INVENTION 
     The invention relates to a blower wheel, and more particularly, to a blower wheel comprising a centerdisk comprising a conical portion, a planar portion for receiving a hub, and an arcuate portion intermediate the conical portion and an outer portion. 
     BACKGROUND OF THE INVENTION 
     A blower wheel with forward curved blades is commonly found in a wide variety of air moving applications. These may include residential furnaces and air handlers as well as larger commercial heating and air conditioning systems. The fans are typically driven by an electric motor that can be coupled either directly to the motor shaft (direct drive), or through a system of sheaves and belts (belt drive). 
     The coupling from the motor to the fan occurs at a central rotating disk, or centerdisk, that contains a means to secure the motor shaft and transmit motive force to the fan blades. The centerdisk is often composed of two formed parts that are nested together to create the centerdisk assembly. A hub containing a set-screw, for attachment to the motor shaft, is fastened into the centerdisk. 
     Due to structural constraints and the need to access the set-screw with a tool a large washer is placed between the two centerdisk parts to provide structural stiffness and clearance to access the set-screw. 
     Representative of the art is U.S. Pat. No. 4,329,118 (1982) A line of forwardly curved blower wheels of different diameters incorporates blades of the same angular extent in all wheels but with the radii of curvature of the individual blades proportional to the diameter of the wheel wherein they are incorporated. In addition, the center disks of the double inlet wheels and the end plates of the single inlet wheels are provided with novel mounting structure comprising segments bent out of the plane of the disk or end plate and secured to opposite ends of the hub member by which the wheel is mounted on a shaft, and the individual blades are retained in complementary slots in the disk or plate and fillet welded to the disk or plate respectively. 
     What is needed is a blower wheel comprising a blower wheel comprising a centerdisk comprising a conical portion, a planar portion for receiving a hub, and an arcuate portion intermediate the conical portion and an outer portion. The present invention meets this need. 
     SUMMARY OF THE INVENTION 
     The primary aspect of the invention is to provide a blower wheel comprising a centerdisk comprising a conical portion, a planar portion for receiving a hub, and an arcuate portion intermediate the conical portion and an outer portion. 
     Other aspects of the invention will be pointed out or made obvious by the following description of the invention and the accompanying drawings. 
     The invention comprises blower wheel comprising a centerdisk comprising a conical portion, a planar portion for receiving a hub, and an arcuate portion intermediate the conical portion and an outer portion, a plurality of blades connected to the outer portion, the blades further connected to a ring, and a hub connected to the planar portion, the hub comprising a fastener for attaching the centerdisk to a shaft. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated in and form a part of the specification, illustrate preferred embodiments of the present invention, and together with a description, serve to explain the principles of the invention. 
         FIG. 1  is a perspective view of a prior art blower wheel. 
         FIG. 2  is a perspective view of a prior art blower wheel. 
         FIG. 3  is a side-end view of a prior art blower wheel. 
         FIG. 4  is a cross-sectional view of a prior art blower wheel. 
         FIG. 5  is a cross-sectional view of a prior art blower wheel. 
         FIG. 6  is a cross-sectional view of a prior art centerdisk. 
         FIG. 7  is a cross-sectional view of an inventive centerdisk. 
         FIG. 8  is a first alternate embodiment. 
         FIG. 9  is a second alternate embodiment. 
         FIG. 10  is a third alternate embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIG. 1  is a perspective view of a prior art blower wheel.  FIG. 2  is a perspective view of a prior art blower wheel. A centrifugal fan with forward curved blades  2  is often constructed of five main components. Blades  2  may be individually formed, or formed as part of a continuous ribbon. 
     A plurality of blades  2  are attached to end-rings  3  by welding, crimping, or any other suitable method. The blades are also fastened to a centerdisk  4  which may be placed at the centerline  5  of the fan, or any other location perpendicular to the axis of rotation  6 . 
     Attached to the centerdisk  4  is a hub  7  that contains a bore for the motor shaft and some means of securing the fan to the motor shaft, namely, a set screw  13 . The hub  7  portions may be placed on either side of the centerdisk depending on the access needed to tighten the set-screw  13  and the position of the motor (not shown). These two hub configurations are referred to as concave  8  and convex  9 . 
       FIG. 3  is a side-end view of a prior art blower wheel.  FIG. 4  is a cross-sectional view of a prior art blower wheel.  FIG. 5  is a cross-sectional view of a prior art blower wheel.  FIG. 6  is a cross-sectional view of a prior art centerdisk. Centerdisk  4  is often composed of two identical formed sheet metal components  101 ,  102  that are nested together to form the complete centerdisk. The prior art geometry for the centerdisk is a frustoconical shape. However, this geometry does not provide adequate access to the set-screw  13  if the conical portion  17  intersects the diameter of the hub  7 . 
     Access can be improved by creating a large planar area adjacent to the hub  7 . However, this only serves to weaken the structure unless additional stiffness is provided by adding an intermediate washer  10 . Use of the washer  10  adds manufacturing costs to the product. The present invention eliminates the washer  10  while also improving tool access and structural integrity. It does this by the combination of the geometry of the arcuate portion  15  and the inverted conical portion  16 , see  FIG. 7 . 
     The prior art design often leads to an interference  11  in the concave hub configuration  8  when accessing the set-screw  13 , for example, with a pneumatic tool T. The convex hub location is shown at position  9 , see  FIG. 4  and  FIG. 6 . 
       FIG. 7  is a cross-sectional view of an inventive centerdisk. The inventive centerdisk  100  comprises a formed portion having an arcuate cross-section portion  15 . Portion  15  could also be characterized as dished. The center disk comprises two components  101 ,  102 , each of circular sheet metal which are stamped into the disclosed cross-sectional shape. Components  101 ,  102  are nested together to form the centerdisk  100 . The double layer  101 ,  102  reinforces and strengthens the centerdisk. 
     Near the center area of the centerdisk, the center of curvature of the arcuate portion  15  is reversed to form a conical portion  16 . Conical portion  16  further comprises a centrally disposed planar portion  160  that accepts a hub  7 . Planar portion  160  extends in a plane normal to the axis of rotation A-A. 
     The arcuate geometry of portion  15  provides improved stiffness over previous designs thereby negating the need for a washer for reinforcement. The arcuate portion  15  further enhances tool T clearance to access a set-screw  13 . 
     Outer portion  14  is connected to blades  2 . Outer portion  14  comprises a cross-sectional form as shown suited for engaging the blades or may be planar as well. 
     An apex  19  for the conical portion  16  is disposed on the same side of the centerdisk as the center of curvature  20  of the arcuate portion  15  having a radius RC, each with respect to an axis A-A. 
     In a first alternate embodiment as shown in  FIG. 8 , conical portion  16  instead comprises an arcuate portion  161  having a center of curvature  201  on the side of the wheel opposite the location of center of curvature  20 . Arcuate portion  15  is arcuate as described in  FIG. 7 . This embodiment is otherwise as described in  FIG. 7 . 
     In a second alternate embodiment as shown in  FIG. 9 , arcuate portion  15  is instead a conical portion  151 . In this second alternate embodiment, conical portion  151  is has an apex  191 . Further, in this second alternate embodiment, arcuate portion  161  is as described in  FIG. 8  and has a center of curvature  201  on the same side of the wheel as the apex  191 . This embodiment is otherwise as described in  FIG. 7 . 
     In a third alternate embodiment as shown in  FIG. 10 , conical portion  16  is combined with a conical portion  151 . Conical portion  151  has apex  191 . Conical portion  16  has apex  19  on the side of the wheel that is opposite apex  191 . This embodiment is otherwise as described in  FIG. 7 . 
     In each of the descriptions, the terms “arcuate” and “conical” refer to a cross-section of the noted portion of the wheel. 
     Although a form of the invention has been described herein, it will be obvious to those skilled in the art that variations may be made in the construction and relation of parts without departing from the spirit and scope of the invention described herein.