Reduced noise diffuser for a motor-fan assembly

Abstract

An air diffuser for a motor-fan unit having reduced blade passage frequencies, and reduced noise generation, includes a baffle plate, external vanes, internal vanes, diffuser ports, and a central opening. The baffle plate of the diffuser is made integral with the internal and external vanes, such that any leaking, rattling, or pure tone noise that may be generated from air movement over the surface of the diffuser are prevented or reduced. Additionally, the number of internal and external vanes provided by the diffuser is that equal to a prime number, thus resulting in a reduction of harmonic and pure tone noise generated during the operation of the motor-fan unit.

1 . A diffuser interposed between a shrouded fan assembly and a motor assembly having a shaft that rotates a fan carried within said shrouded fan assembly, the diffuser comprising: 
 a baffle plate having a motor side and a fan side, said baffle plate having an opening therethrough; and    a plurality of vanes extending from said motor side, each said vane having an external portion which radially extends from said baffle plate, wherein adjacent vanes have a port therebetween, said plurality of vanes directing airflow generated by the fan from said fan side through said ports to said motor side.    
   
   
       2 . The diffuser according to  claim 1 , wherein each said vane has an internal portion contiguous with said external portion, said internal portions extending toward said opening.  
   
   
       3 . The diffuser according to  claim 2 , wherein said vanes are curvilinear and spaced apart from each other.  
   
   
       4 . The diffuser according to  claim 2 , wherein said internal portions terminate prior to reaching said opening so as to collectively form a collection chamber for the airflow.  
   
   
       5 . The diffuser according to  claim 1 , wherein each said vane has a plate edge at said motor side and ring edge opposite said plate edge.  
   
   
       6 . The diffuser according to  claim 5 , further comprising: 
 a vane support ring connected to at least some of said vanes.    
   
   
       7 . The diffuser according to  claim 6 , wherein said vane support ring is connected to at least some of said ring edges, said vane support ring having an inner edge with a diameter at least equal to or larger than said baffle plate's diameter.  
   
   
       8 . The diffuser according to  claim 1 , wherein each said vane comprises a radial turning vane.  
   
   
       9 . The diffuser according to  claim 1 , wherein said baffle plate is annular.  
   
   
       10 . The diffuser according to  claim 1 , wherein said plurality of vanes total a number equal to a prime number.  
   
   
       11 . The diffuser according to  claim 1 , further comprising: 
 at least one brush cap connected to said motor side of said baffle plate.    
   
   
       12 . A motor-fan assembly comprising: 
 a field winding;    an armature having a shaft, said armature rotatably mounted within said field winding;    a fan attached to said shaft; and    a diffuser interposed between said fan and said field winding, said diffuser comprising:    a baffle plate having a motor side and a fan side;    said baffle plate having an opening therethrough;    a plurality of vanes extending from said motor side;    each said vane having an external portion which radially extends from said baffle plate wherein adjacent vanes have a port therebetween; and    said plurality of vanes directing airflow generated by the fan from said fan side through said ports to said motor side.    
   
   
       13 . The motor assembly according to  claim 12 , wherein each said vane has an internal portion contiguous with said external portion, said internal portion extending toward said opening.  
   
   
       14 . The motor assembly according to  claim 13 , wherein said vanes are curvilinear and spaced apart from each other.  
   
   
       15 . The motor assembly according to  claim 13 , wherein said internal portions terminate prior to reaching said opening so as to collectively form a collection chamber for the airflow.  
   
   
       16 . The motor assembly according to  claim 12 , wherein each said vane has a plate edge at said motor side and ring edge opposite said plate edge.  
   
   
       17 . The motor assembly according to  claim 16 , further comprising: 
 a vane support ring connected to at least some of said vanes.    
   
   
       18 . The motor assembly according to  claim 17 , wherein said vane support ring is connected to at least some of said ring edges, said vane support ring having an inner edge with a diameter at least equal to or larger than said baffle plate's diameter.  
   
   
       19 . The motor assembly according to  claim 12 , wherein each said vane comprises a radial turning vane.  
   
   
       20 . The motor assembly according to  claim 19 , wherein said plurality of radial turning vanes total a number equal to a prime number.  
   
   
       21 . The motor assembly according to  claim 12 , wherein said baffle plate is annular.  
   
   
       22 . The motor assembly according to  claim 12 , wherein said plurality of vanes total a number equal to a prime number.