Combination airflow straightener and finger guard for use with a fan

Abstract

A combination airflow straightener and finger guard straightens airflow and minimize the chance of fingers or other objects coming into contact with rotating blades of a fan, and includes a plurality of vanes that extend radially outward from a hub to an outer frame of the combination airflow straightener and finger guard. Each vane can be considered as having three portions. The first portion is closest to the fan and is parallel to the airflow leaving the fan. The second portion is farthest from the fan and is aligned with the axis of rotation of the fan (or some other desired exhaust vector). The third portion is curved to link the first portion to the second portion to straighten the airflow to the desired exhaust vector, with the space between each pair of vanes forming a plenum that straightens the airflow by removing the rotational components from the airflow.

What is claimed is:  
     
         1 . A combination airflow straightener and finger guard having a fan side and an exhaust side, for use with a fan, comprising: 
 a hub;    a frame; and    a plurality of vanes extending radially from the hub to the frame, wherein a maximum angular distance separating adjacent vanes is sufficiently small to provide effective protection against a finger being inserted between adjacent vanes from the exhaust side to the fan side, and two or more adjacent vanes each comprise a first portion originating at the fan side that is approximately parallel to airflow leaving the fan, a second portion ending at the exhaust side, and a third portion that links the first portion to the second portion to straighten airflow leaving the exhaust side.    
     
     
         2 . The combination airflow straightener and finger guard of  claim 1  wherein the maximum angular distance separating adjacent vanes is no more than ½ of an inch.  
     
     
         3 . The combination airflow straightener and finger guard of  claim 1  wherein the second portion of each vane is substantially parallel to an axis of rotation of the fan when the combination airflow straightener and finger guard is mounted to the fan.  
     
     
         4 . The combination airflow straightener and finger guard of  claim 1  wherein the second portion of each vane is angularly displaced by a common angle from an axis of rotation of the fan when the combination airflow straightener and finger guard is mounted to the fan.  
     
     
         5 . An assembly comprising: 
 an axial fan; and    a combination airflow straightener and finger guard having a fan side and an exhaust side and mounted to the axial fan, the combination airflow straightener and finger guard comprising: 
 a hub;  
 a frame; and  
 a plurality of vanes extending radially from the hub to the frame, wherein a maximum angular distance separating adjacent vanes is sufficiently small to provide effective protection against a finger being inserted between adjacent vanes and coming into contact with rotating blades of the axial fan, and two or more adjacent vanes each comprise a first portion originating at the fan side that is approximately parallel to airflow leaving the axial fan, a second portion ending at the exhaust side, and a third portion that links the first portion to the second portion to straighten airflow leaving the exhaust side.  
   
     
     
         6 . The assembly of  claim 5  wherein the maximum angular distance separating adjacent vanes is no more than ½ of an inch.  
     
     
         7 . The assembly of  claim 6  wherein the second portion of each vane is substantially parallel to an axis of rotation of the axial fan.  
     
     
         8 . The assembly of  claim 6  wherein the second portion of each vane is angularly displaced by a common angle from an axis of rotation of the axial fan.  
     
     
         9 . An assembly comprising: 
 an upstream axial fan;    a downstream axial fan coupled to the upstream fan in a redundant N+1 serial configuration; and    a combination airflow straightener and finger guard having a fan side and an exhaust side and mounted between the upstream and downstream axial fans, the combination airflow straightener and finger guard comprising: 
 a hub;  
 a frame; and  
 a plurality of vanes extending radially from the hub to the frame, wherein a maximum angular distance separating adjacent vanes is sufficiently small to provide effective protection against a finger being inserted between adjacent vanes and coming into contact with rotating blades of the upstream axial fan, and two or more adjacent vanes each comprise a first portion originating at the fan side that is approximately parallel to airflow leaving the upstream axial fan, a second portion ending at the exhaust side, and a third portion that links the first portion to the second portion to straighten airflow leaving the exhaust side.  
   
     
     
         10 . The assembly of  claim 9  wherein the maximum angular distance separating adjacent vanes is no more than ½ of an inch.  
     
     
         11 . The assembly of  claim 9  wherein the second portion of each vane is substantially parallel to an axis of rotation of the downstream axial fan.