Centrifugal fan

Abstract

A centrifugal fan for use with an engine includes a hub defining a rotational axis, a plurality of blades arranged about the rotational axis, and a screen coupled to the hub and blades for co-rotation therewith. The hub, the blades, and the screen are integrally formed as a single piece.

We claim: 
     
         1 . A centrifugal fan for use with an engine, comprising:
 a hub including a rotational axis;   a plurality of blades arranged about the rotational axis and coupled to the hub for co-rotation therewith, wherein each blade includes a pressure surface, a suction surface opposite the pressure surface, a leading edge defining a boundary between the suction surface and the pressure surface, and a trailing edge opposite the leading edge; and   a screen coupled to the hub and the blades for co-rotation therewith, wherein the hub, the blades, and the screen are integrally formed as a single piece, wherein the plurality of blades comprises a plurality of main blades and a plurality of splitter blades, wherein the leading edge of each main blade is integral with the hub and wherein the leading edge of each splitter blade is spaced from the hub.   
     
     
         2 . (canceled) 
     
     
         3 . The centrifugal fan of  claim 1 , wherein each of the blades defines
 a nose-tail line connecting the leading edge and the trailing edge, the nose-tail line being a straight line and defining a length; and   a mean line half-way between the pressure surface and the suction surface and intersecting the nose-tail line at the leading edge and the trailing edge.   
     
     
         4 . (canceled) 
     
     
         5 . The centrifugal fan of  claim 3 , wherein each of the blades includes a camber between about 0.1 and about 0.2. 
     
     
         6 . The centrifugal fan of  claim 5 , wherein the plurality of blades comprises a plurality of main blades and a plurality of splitter blades, wherein the camber of the splitter blades is the same as the camber of the main blades. 
     
     
         7 . The centrifugal fan of  claim 4 , wherein the main blades and the splitter blades are alternately spaced about the rotational axis. 
     
     
         8 . The centrifugal fan of  claim 1 , wherein the screen includes a plurality of concentric rings coaxial with the rotational axis and interconnected by the blades. 
     
     
         9 . The centrifugal fan of  claim 1 , wherein each of the blades includes at least one notch in a top edge of the blade, the notch configured to allow an airflow to pass between adjacent blades. 
     
     
         10 . An engine comprising:
 a crankcase;   a cover at least partially enclosing the crankcase; and   a centrifugal fan that is rotatable while the engine is in use for discharging a cooling airflow between the crankcase and the cover, the centrifugal fan including
 a hub including a rotational axis, 
 a plurality of blades arranged about the rotational axis and coupled to the hub for co-rotation therewith, wherein each blade includes a pressure surface, a suction surface opposite the pressure surface, a leading edge defining a boundary between the suction surface and the pressure surface, and a trailing edge opposite the leading edge, and 
 a screen coupled to the hub and the blades for co-rotation therewith; 
   wherein the hub, the blades, and the screen are integrally formed as a single piece, and wherein the plurality of blades comprises a plurality of main blades and a plurality of splitter blades, and wherein the leading edge of each main blade is integral with the hub and wherein the leading edge of each splitter blade is spaced from the hub.   
     
     
         11 . (canceled) 
     
     
         12 . The engine of  claim 10 , wherein each of the blades defines
 a nose-tail line connecting the leading edge and the trailing edge, the nose-tail line being a straight line and defining a length; and   a mean line half-way between the pressure surface and the suction surface and intersecting the nose-tail line at the leading edge and the trailing edge.   
     
     
         13 . (canceled) 
     
     
         14 . The engine of  claim 12 , wherein each blade includes a camber between about 0.1 and about 0.2. 
     
     
         15 . The engine of  claim 14 , wherein the plurality of blades comprises a plurality of main blades and a plurality of splitter blades, wherein the camber of the splitter blades is the same as the camber of the main blades. 
     
     
         16 . The engine of  claim 10 , wherein the main blades and the splitter blades are alternately spaced about the rotational axis. 
     
     
         17 . The engine of  claim 10 , wherein the screen includes a plurality of concentric rings coaxial with the rotational axis and interconnected by the blades. 
     
     
         18 . The engine of  claim 10 , wherein each of the blades includes at least one notch in a top edge of the blade, the notch configured to allow an airflow to pass between adjacent blades. 
     
     
         19 . The engine of  claim 10 , wherein each of the blades includes a top edge attached to the screen and a bottom edge, and wherein the bottom edge of each of the blades is a free edge. 
     
     
         20 . The engine of  claim 19 , wherein the bottom edge includes a thickness less than that of the top edge.