Environmentally friendly filter cartridge

Abstract

A filter cartridge which is environmentally friendly in that it is made up of components which are all incinerateable. The ends of a filter element are sealed using potting compound and plastic endcaps. The upper endcap, which is closed, has a pressure relief aperture associated therewith to prevent bowing. In a plugged filter condition the high downward pressure introduced on the upper endcap is compensated by providing the cartridge with centering ribs which bottom on an associated ledge in the housing to provide a positive stop for the top endcap, preventing it from being driven down into and through the filter element. Rubber gaskets are associated with the respective endcaps, and are reliably secured to the endcaps by being snap fit into grooves molded into the plastic of the endcaps. The lower endcap utilizes a simple radial seal gasket which is both highly effective and also positioned to avoid structural crushing forces on the cartridge. A keying system prevents the installation of improper filters.

1 - 10 . (canceled)  
     
     
         11 . An environmentally friendly filter cartridge constructed to fit in a filter housing, the filter cartridge comprising: 
 a cylindrical filter element having an internal bore of a size capable of sliding over a centertube in a corresponding housing;    a first endcap coupled to a first end of the filter element, the first endcap having an open center sized to permit the centertube to pass therethrough; and    a second endcap coupled to a second end of the filter element, the second endcap having at least one key extending from the second endcap into the internal bore, the at least one key sized to engage the a corresponding key position on the centertube, wherein the at least one key engages the corresponding key position at only one angular position of the filter cartridge relative to the centertube such that the filter cartridge can be loaded in only one orientation.    
     
     
         12 . The filter cartridge as in  claim 11  wherein the second endcap has a plurality of keys extending from the second endcap into the internal bore.  
     
     
         13 . The filter cartridge as in  claim 12  wherein the plurality of keys are substantially identical in size.  
     
     
         14 . The filter cartridge as in  claim 12  wherein the plurality of keys are positioned in a generally circular orientation.  
     
     
         15 . The filter cartridge as in  claim 11  wherein the corresponding key position is a slot in the centertube.  
     
     
         16 . The filter cartridge as in  claim 11  wherein the number of keys is equivalent to the number of key positions on the centertube.  
     
     
         17 . The filter cartridge as in  claim 11  wherein second endcap closes the internal bore at the second end of the filter element.  
     
     
         18 . The filter cartridge as in  claim 11  further comprising a key circle extending from the second endcap into the internal bore and surrounding the at least one key.  
     
     
         19 . The filter cartridge as in  claim 11  wherein the filter cartridge comprises no metal parts.  
     
     
         20 . The filter cartridge as in  claim 11  wherein the internal bore has no integral supporting centertube.  
     
     
         21 . The filter cartridge as in  claim 11  further including the complimentary housing for receiving the filter cartridge, the housing having the centertube fixed therein for supporting the inner bore of the cartridge when inserted in the housing, and a cover threaded onto the housing.  
     
     
         22 . The filter cartridge as in  claim 11  wherein the at least one key extends in an axial direction relative to the internal bore.