Fan noise attenuator

Abstract

In some embodiments, a passive noise attenuator reduces fan noise in an electronic system. Other embodiments are disclosed and claimed.

1 . An apparatus, comprising: 
 a fan assembly having an inlet side and an outlet side; and    a sound absorbing structure positioned on the inlet side of the fan assembly and proximate to the fan assembly.    
   
   
       2 . The apparatus of  claim 1 , wherein the fan assembly comprises a fan and a motor connected to the fan, and wherein the sound absorbing structure is attached to the motor.  
   
   
       3 . The apparatus of  claim 2 , wherein the sound absorbing structure is adapted to support the motor and fan inside a chassis.  
   
   
       4 . The apparatus of  claim 2 , wherein the sound absorbing structure comprises: 
 a rigid core attached to the motor; and    sound absorbing material disposed around the rigid core.    
   
   
       5 . The apparatus of  claim 4 , wherein the sound absorbing material has a general conical shape with a smaller diameter end of the conical shape being nearer to the fan assembly.  
   
   
       6 . The apparatus of  claim 4 , wherein the sound absorbing material includes a series of annular cones having smaller diameter cones nearer to the fan assembly.  
   
   
       7 . The apparatus of  claim 1 , further comprising: 
 an exit cone positioned proximate to the fan assembly on an outlet side of the fan assembly.    
   
   
       8 . The apparatus of  claim 7 , wherein the exit cone is adapted to reduce air disturbances on the outlet side of the fan assembly.  
   
   
       9 . The apparatus of  claim 8 , wherein the fan assembly comprises a fan having a central hub, and wherein the exit cone is attached to the central hub.  
   
   
       10 . The apparatus of  claim 9 , further comprising: 
 a fan housing positioned around blades of the fan, wherein the fan housing defines an inlet bellmouth which is adapted to cooperate with the sound absorbing structure to promote an inflow of air at directions transverse to an axis of the fan.    
   
   
       11 . A method, comprising: 
 providing a fan assembly; and    positioning a sound absorbing material in front of an inlet side of the fan assembly.    
   
   
       12 . The method of  claim 11 , further comprising: 
 disposing the sound absorbing material around a rigid core.    
   
   
       13 . The method of  claim 12 , further comprising; 
 attaching the rigid core to a motor of the fan assembly.    
   
   
       14 . The method of  claim 13 , further comprising: 
 supporting the fan motor in a chassis with the rigid core.    
   
   
       15 . The method of  claim 14 , further comprising: 
 attaching the rigid core to a panel of the chassis.    
   
   
       16 . The method of  claim 11 , further comprising: 
 forming the sound absorbing material with a series of annular cones having increasing diameters along an axis.    
   
   
       17 . The method of  claim 11 , further comprising: 
 reducing air disturbances on an outlet side of the fan assembly with an exit cone.    
   
   
       18 . The method of  claim 17 , further comprising: 
 integrating the exit cone with a central hub of the fan assembly.    
   
   
       19 . The method of  claim 18 , further comprising: 
 promoting an inflow of air at directions transverse to an axis of the fan assembly with a fan housing positioned around blades of the fan which cooperates with the sound absorbing material.    
   
   
       20 . A system, comprising: 
 a chassis;    a system board inside the chassis;    an electronic component on the system board;    a fan assembly inside the chassis, the fan assembly having an inlet side and an outlet side; and    a sound absorbing structure positioned on the inlet side of the fan assembly and proximate to the fan assembly.    
   
   
       21 . The system of  claim 20 , wherein the fan assembly comprises a fan and a motor connected to the fan, and wherein the sound absorbing structure is attached to the motor.  
   
   
       22 . The system of  claim 21 , wherein the sound absorbing structure is adapted to support the motor and fan inside the chassis.  
   
   
       23 . The system of  claim 22 , wherein the sound absorbing structure comprises: 
 a rigid core attached to the motor; and    sound absorbing material disposed around the rigid core.    
   
   
       24 . The system of  claim 23 , wherein the rigid core is attached to a panel of the chassis.  
   
   
       25 . The system of  claim 23 , wherein the sound absorbing material has a general conical shape with a smaller diameter end of the conical shape being nearer to the fan assembly.  
   
   
       26 . The system of  claim 23 , wherein the sound absorbing material includes a series of annular cones having smaller diameter cones nearer to the fan assembly.  
   
   
       27 . The system of  claim 20 , further comprising: 
 an exit cone positioned proximate to the fan assembly on an outlet side of the fan assembly.    
   
   
       28 . The system of  claim 27 , wherein the exit cone is adapted to reduce air disturbances on the outlet side of the fan assembly.  
   
   
       29 . The system of  claim 28 , wherein the fan assembly comprises a fan having a central hub, and wherein the exit cone is attached to the central hub.  
   
   
       30 . The system of  claim 29 , further comprising: 
 a fan housing positioned around blades of the fan, wherein the fan housing defines an inlet bellmouth which is adapted to cooperate with the sound absorbing structure to promote an inflow of air at directions transverse to an axis of the fan.