Filter system for an electronic equipment enclosure

Abstract

A filter system including a method for self cleaning the filter system of an electronic equipment enclosure where air flow is monitored either by monitoring fan performance or air flow velocity through the enclosure. The system includes two filters elements, an upstream ASHRAE or HEPA filter element to block particulate matter and a downstream PTFE filter element to block water vapor. The ASHRAE or HEPA filter element is relatively inexpensive and easy to clean. The PTFE filter element is more expensive and difficult to clean. Thus, the cheaper filter is used to protect the more expensive filter from contaminants and to increase its useful life. The method of self cleaning includes stopping the fan when a signal is received indicating a predetermined resistance to air flow which is a function of blockage of the filter elements, thereafter operating the fan at an increased rotational velocity to determine whether the fan itself is malfunctioning, thereafter slowing and stopping the fan to allow the fan to be reversed, rotating the fan in reverse for a predetermined period of time, such as five minutes, thereafter slowing and stopping the fan and returning the fan to its usual rotational velocity and direction. If the resistance to air flow is still above a predetermined level, the fan is again slowed, stopped and reversed and then returned to normal operation. The reversal operation can be conducted a multiple number of times, however, after a predetermined number, a signal is sent requesting maintenance.

1 . A filter system having at least two filter elements for use in an electronic equipment enclosure comprising: 
 an air flow path formed through said enclosure;    a first filter element mounted to said enclosure such that air in said air flow path moves through said first filter element; and    a second filter element mounted to said enclosure downstream of said first filter element such that air in said air flow path passing through said first filter element thereafter passes through said second filter element, said first filter element structured to protect said second filter element and extend the useful life of said second filter element.    
   
   
       2 . The system as claimed in  claim 1  wherein: 
 said first filter element is structured to filter particulate matter from the air of said air flow path; and    said second filter element is structured to filter water vapor from the air of said air flow path.    
   
   
       3 . The system as claimed in  claim 1  wherein: 
 said first filter element is less expensive than said second filter element.    
   
   
       4 . The system as claimed in  claim 1  wherein: 
 said first filter element is structured to be easier to clean than said second filter element.    
   
   
       5 . The system as claimed in  claim 1  wherein: 
 said first filter element is positioned for easier access than said second filter element.    
   
   
       6 . The system as claimed in  claim 1  wherein: 
 said first filter element is structured to filter particulate matter from the air of said air flow path;    said second filter element is structured to filter water vapor from the air of said air flow path; and    said first filter element is positioned for easier access than said second filter element.    
   
   
       7 . The system as claimed in  claim 6  wherein: 
 said first filter element is less expensive than said second filter element.    
   
   
       8 . The system as claimed in  claim 7  wherein: 
 said first filter element is structured to be easier to clean than said second filter element.    
   
   
       9 . The system as claimed in  claim 1  wherein: 
 said first filter element is an ASHRAE or HEPA filter element.    
   
   
       10 . The system as claimed in  claim 1  wherein: 
 said second filter element is a PTFE filter element.    
   
   
       11 . The system as claimed in  claim 2  wherein: 
 said first filter element is an ASHRAE or HEPA filter element.    
   
   
       12 . The system as claimed in  claim 11  wherein: 
 said second filter element is a PTFE filter element.    
   
   
       13 . The system as claimed in  claim 5  wherein: 
 said first filter element is an ASHRAE or HEPA filter element.    
   
   
       14 . The system as claimed in  claim 13  wherein: 
 said second filter element is a PTFE filter element.    
   
   
       15 . The system as claimed in  claim 3  wherein: 
 said first filter element is an ASHRAE or HEPA filter element.    
   
   
       16 . The system as claimed in  claim 15  wherein: 
 said second filter element is a PTFE filter element.    
   
   
       17 . The system as claimed in  claim 16  wherein: 
 said first filter element is structured to be easier to clean than said second filter element; and    said first filter element is positioned for easier access than said second filter element.    
   
   
       18 . The system as claimed in  claim 1  including: 
 a sensor for indicating that said first filter element should be cleaned or replaced.    
   
   
       19 . The system as claimed in  claim 1  including: 
 a sensor mounted to said housing for monitoring air flow resistance along said air flow path and for providing a signal indicating a predetermined resistance to air flow along said air flow path; and    a control mounted to said housing and responsive to said signal for altering the operation of a fan creating said air flow.    
   
   
       20 . The system as claimed in  claim 19  wherein: 
 said control causes said fan to increase rotational velocity to attempt clearing any clogging of said filter elements.    
   
   
       21 . The system as claimed in  claim 20  wherein: 
 said control causes said fan to reverse rotational direction.    
   
   
       22 . The system as claimed in  claim 21  wherein: 
 said control causes said fan to increase rotational velocity before reversing rotational direction.    
   
   
       23 . The system as claimed in  claim 22  wheein: 
 said control cycles said fan between increasing rotational velocity and reversing rotational direction.    
   
   
       24 . The system as claimed in  claim 23  wherein: 
 said first filter element is structured to filter particulate matter from the air of said air flow path; and    said second filter element is structured to filter water vapor from the air of said air flow path.    
   
   
       25 . The system as claimed in  claim 24  wherein: 
 said first filter element is positioned for easier access than said second filter element.    
   
   
       26 . The system as claimed in  claim 24  wherein: 
 said first filter element is structured to be easier to clean than said second filter element.