Circumferentially pleated filter assembly and method of forming the same

Abstract

A filter assembly is provided which includes an outer filter sleeve formed at least in part by a plurality of pleats, an inner filter sleeve formed at least in part by a plurality of pleats, wherein the inner and outer filter sleeves define a passage therebetween. An inlet cap is secured to a first end of the inner and outer filter sleeves and it has at least one inlet port communicating with the passage, and an end cap is secured to a second end of the inner and outer filter sleeves and it has an end surface closing the passage. Methods of forming such a filter assembly are also provided.

1 . A filter element comprising: 
 a) an outer filter sleeve formed at least in part by a plurality of longitudinally extending pleats;    b) an inner filter sleeve formed at least in part by a plurality of longitudinally extending pleats, the inner and outer filter sleeves defining a passage therebetween;    c) an inlet cap secured to a first end of the inner and outer filter sleeves and having at least one inlet port communicating with the passage; and    d) an end cap secured to a second end of the inner and outer filter sleeves and having an end surface closing the passage.    
   
   
       2 . A filter element as recited in  claim 1 , wherein the outer filter sleeve includes a plurality of circumferentially disposed arcuate pleats.  
   
   
       3 . A filter element as recited in  claim 1 , wherein the inner filter sleeve includes a plurality of circumferentially disposed arcuate pleats.  
   
   
       4 . A filter element as recited in  claim 2 , wherein adjoining circumferentially disposed arcuate pleats of the outer filter sleeve partially overlap one another.  
   
   
       5 . A filter element as recited in  claim 3 , wherein adjoining circumferentially disposed arcuate pleats of the inner filter sleeve partially overlap one another.  
   
   
       6 . A filter element as recited in  claim 4 , wherein adjoining circumferentially disposed arcuate pleats of the outer filter sleeve overlap one another over approximately 50% to 80% of the arc length of the pleats.  
   
   
       7 . A filter element as recited in  claim 5 , wherein adjoining circumferentially disposed arcuate pleats of the inner filter sleeve overlap one another over approximately 50% to 80% of the arc length of the pleats.  
   
   
       8 . A filter element as recited in  claim 2 , wherein adjoining circumferentially disposed arcuate pleats of the outer filter sleeve are circumferentially spaced from one another.  
   
   
       9 . A filter element as recited in  claim 3 , wherein adjoining circumferentially disposed arcuate pleats of the inner filter sleeve are circumferentially spaced from one another.  
   
   
       10 . A filter element as recited in  claim 2 , wherein the circumferentially disposed arcuate pleats of the outer filter sleeve are uniformly distributed about the circumference of the outer filter sleeve.  
   
   
       11 . A filter element as recited in  claim 3 , wherein the circumferentially disposed arcuate pleats of the inner filter sleeve are uniformly distributed about the circumference of the inner filter sleeve.  
   
   
       12 . A filter element as recited in  claim 2 , wherein the circumferentially disposed arcuate pleats of the outer filter sleeve have equal arc length.  
   
   
       13 . A filter element as recited in  claim 3 , wherein the circumferentially disposed arcuate pleats of the inner filter sleeve have equal arc length.  
   
   
       14 . A filter element as recited in  claim 2 , wherein each of the circumferentially disposed arcuate pleats of the outer filter portion has a radially outer pleat leg and a radially inner pleat leg, and wherein the arc length of the radially inner pleat leg is shorter than the arc length of the radially outer pleat leg.  
   
   
       15 . A filter element assembly as recited in  claim 3 , wherein each of the circumferentially disposed arcuate pleats of the inner filter portion has a radially outer pleat leg and a radially inner pleat leg, and wherein the arc length of the radially inner pleat leg is shorter than the arc length of the radially outer pleat leg.  
   
   
       16 . A filter element as recited in  claim 1 , wherein the outer filter sleeve and the inner filter sleeve are each formed by a multi-layered pleated composite including at least one layer of filter media, an upstream support/drainage layer and a downstream support/drainage layer.  
   
   
       17 . A filter element as recited in  claim 16 , wherein the at least one layer of filter media is selected from the group of filter materials consisting of melt-blown filter media, nonwoven filter media, glass fiber media and needled felt media.  
   
   
       18 . A filter element as recited in  claim 16 , wherein the multi-layered composite includes plural layers of filter media each having the same porosity.  
   
   
       19 . A filter element as recited in  claim 16 , wherein the multi-layered composite includes plural layers of filter media each having a different porosity.  
   
   
       20 . A filter element as recited in  claim 16 , wherein the support/drainage layers of the multi-layered composite are formed from materials selected from the group consisting of extruded polymeric meshes, nets and spun bonded polymeric non-wovens.  
   
   
       21 . A filter element as recited in  claim 1 , wherein the inlet cap is bonded to the outer filter sleeve and the inner filter sleeve.  
   
   
       22 . A filter element as recited in  claim 1 , wherein the end cap is bonded to the outer filter sleeve and the inner filter sleeve.  
   
   
       23 . A filter element as recited in  claim 1 , wherein the inlet cap has a two-piece construction that includes an inner portion and an outer portion, and wherein the inner filter sleeve is bonded to the inner portion of the inlet cap and the outer filter sleeve is bonded to the outer portion of the inlet cap.  
   
   
       24 . A filter element as recited in  claim 1 , wherein the end cap has a two-piece construction that includes an inner portion and an outer portion, and wherein the inner filter sleeve is bonded to the inner portion of the end cap and the outer filter sleeve is bonded to the outer portion of the end cap.  
   
   
       25 . A filter element as recited in  claim 1 , wherein an elastomeric seal is molded over an outer periphery of the inlet cap.  
   
   
       26 . A filter element as recited in  claim 1 , wherein the inlet cap has a closed end surface.  
   
   
       27 . A filter element as recited in  claim 1 , wherein the inlet cap has an open end surface.  
   
   
       28 . A filter element as recited in  claim 1 , further comprising a sheath surrounding the outer filter sleeve and formed from a material having a relatively open porosity.  
   
   
       29 . A filter element as recited in  claim 1 , wherein the inner filter sleeve defines a central bore of the filter assembly and the end cap includes a central exit port communicating with the central bore.  
   
   
       30 . A filter element comprising: 
 a) a radially outer filter sleeve formed by longitudinally extending circumferentially disposed arcuate pleats;    b) a radially inner filter sleeve arranged concentrically with the radially outer filter sleeve and formed by longitudinally extending circumferentially disposed arcuate pleats, the inner and outer filter sleeves defining an annular passage therebetween;    c) an inlet cap secured to a first end of the inner and outer filter sleeves and having at least one inlet port communicating with the annular passage; and    d) an end cap secured to a second end of the inner and outer filter sleeves and having an annular end surface closing the annular passage.    
   
   
       31 . A filter element as recited in  claim 30 , wherein adjoining circumferentially disposed pleats of the outer filter sleeve partially overlap one another, and wherein adjoining circumferentially disposed pleats of the inner filter sleeve partially overlap one another.  
   
   
       32 . A filter element as recited in  claim 30 , wherein adjoining circumferentially disposed pleats of the outer filter sleeve overlap one another over approximately 50% to 80% of the arc length of the pleats, and wherein adjoining circumferentially disposed arcuate pleats of the inner filter sleeve overlap one another over approximately 50% to 80% of the arc length of the pleats.  
   
   
       33 . A filter element as recited in  claim 30 , wherein adjoining circumferentially disposed arcuate pleats of the outer filter sleeve are circumferentially spaced from one another, and wherein adjoining circumferentially disposed arcuate pleats of the inner filter sleeve are circumferentially spaced from one another.  
   
   
       34 . A filter element as recited in  claim 30 , wherein the circumferentially disposed arcuate pleats of the outer filter sleeve are uniformly distributed about the circumference of the outer filter sleeve, and wherein the circumferentially disposed arcuate pleats of the inner filter sleeve are uniformly distributed about the circumference of the inner filter sleeve.  
   
   
       35 . A filter element as recited in  claim 30 , wherein the circumferentially disposed arcuate pleats of the outer filter sleeve have equal arc length, and wherein the circumferentially disposed arcuate pleats of the inner filter sleeve have equal arc length.  
   
   
       36 . A filter element as recited in  claim 30 , wherein the outer filter sleeve and the inner filter sleeve are each formed by a multi-layered pleated composite including at least one layer of filter media, an upstream support/drainage layer and a downstream support/drainage layer.  
   
   
       37 . A filter element as recited in  claim 30 , wherein the inlet cap and the end cap are bonded to the outer filter sleeve and the inner filter sleeve.  
   
   
       38 . A filter element as recited in  claim 30 , wherein at least one of the inlet cap and the end cap has a two-piece construction.  
   
   
       39 . A filter element as recited in  claim 30 , wherein an elastomeric seal is molded over an outer periphery of the inlet cap.  
   
   
       40 . A filter element as recited in  claim 30 , further comprising a sheath surrounding the radially outer filter sleeve and formed from a material having a relatively open porosity.  
   
   
       41 . A filter element as recited in  claim 30 , further comprising a sheath covering a radially inner surface of the radially inner filter sleeve and formed from a material having a relatively open porosity.  
   
   
       42 . A filter element as recited in  claim 30 , wherein the inner filter sleeve defines a central bore of the filter assembly and the end cap includes a central exit port communicating with the central bore.  
   
   
       43 . A filter element comprising: 
 a) a radially outer filter sleeve formed by a multi-layered pleated composite including a plurality of longitudinally extending circumferentially disposed arcuate pleats;    b) a radially inner filter sleeve arranged concentrically with the radially outer filter sleeve and formed by a multi-layered pleated composite including a plurality of longitudinally extending circumferentially disposed arcuate pleats, wherein the inner filter sleeve defines a central bore, and wherein the inner and outer filter sleeves define an annular passage therebetween;    c) an inlet cap secured to an upper end of the inner and outer filter sleeves and having at least one inlet port communicating with the annular passage;    d) an end cap secured to a lower end of the inner and outer filter sleeves, having an annular end surface closing the annular passage and a central exit port communicating with the central bore; and    e) a porous sheath surrounding the radially outer filter sleeve.    
   
   
       44 . A filter element as recited in  claim 43 , wherein the inner filter sleeve and the outer filter sleeve are bonded to side surfaces of the inlet cap and end cap.  
   
   
       45 . A filter element as recited in  claim 43 , wherein the inner filter sleeve and the outer filter sleeve are bonded to end surfaces of the inlet cap and end cap.  
   
   
       46 . A filter element as recited in  claim 43 , wherein the multi-layered pleated composite forming the inner filter sleeve and the outer filter sleeve include at least one layer of filter media, an upstream support/drainage layer and a downstream support/drainage layer.  
   
   
       47 . A filter element as recited in  claim 46 , wherein the at least one layer of filter media is selected from the group of filter materials consisting of melt-blown filter media and microporous membranes.  
   
   
       48 . A filter element as recited in  claim 46 , wherein the multi-layered pleated composite includes plural layers of filter media each having the same porosity.  
   
   
       49 . A filter element as recited in  claim 46 , wherein the multi-layered pleated composite includes plural layers of filter media each having a different porosity.  
   
   
       50 . A filter element as recited in  claim 46 , wherein the support/drainage layers of the multi-layered pleated composite are formed from materials selected from the group consisting of extruded polymeric meshes, nets and spun bonded polymeric non-wovens.  
   
   
       51 . A filter assembly comprising: 
 a) a housing having an interior chamber and a removable cover enclosing the interior chamber, and including an inlet conduit for delivering unfiltered fluid to the interior chamber and an outlet conduit for carrying filtered fluid from the interior chamber; and    b) a filter element disposed within the interior chamber of the housing and including concentrically arranged radially inner and radially outer filter sleeves each having a plurality of longitudinally extending circumferentially disposed arcuate pleats, wherein the inner and outer filter sleeves define an annular passage therebetween for receiving unfiltered fluid from the inlet conduit of the housing, and wherein the inner filter sleeve defines a central bore communicating with the outlet conduit of the housing, an inlet cap secured to an upper end of the inner and outer filter sleeves and having a plurality of inlet ports communicating with the annular passage, and an end cap secured to a lower end of the inner and outer filter sleeves and having a central exit port communicating with the central bore.    
   
   
       52 . A filter assembly as recited in  claim 51 , wherein the inlet cap includes an over-molded peripheral sealing surface for sealingly engaging the cover of the housing when the filter assembly is enclosed therein.  
   
   
       53 . A filter assembly as recited in  claim 51 , wherein the inlet cap has an open end surface with a central aperture formed therein for sealingly engaging the inlet conduit of the housing.  
   
   
       54 . A filter assembly as recited in  claim 51 , wherein the inlet cap has a closed end surface.  
   
   
       55 . A filter assembly as recited in  claim 51 , further comprising a perforated basket for supporting the filter assembly within the housing.  
   
   
       56 . A method of forming a filter element comprising the steps of: 
 a) preparing a plurality of upstanding pleats each having first and second pleat legs, wherein the first pleat leg of one pleat is joined to the second pleat leg of a preceding pleat by a medial pleat section;    b) moving the upstanding pleats into an overlapped condition wherein each medial pleat section becomes part of the second leg of a preceding pleat; and    c) forming the overlapped pleats into a cylindrical configuration.    
   
   
       57 . A method of forming a filter element according to  claim 56 , wherein the step of preparing a plurality of upstanding pleats includes forming the upstanding pleats with first and second pleat legs of equal height.  
   
   
       58 . A method of forming a filter element according to  claim 56 , wherein the step of preparing a plurality of upstanding pleats includes forming the upstanding pleats with first and second pleat legs of different height.  
   
   
       59 . A method of forming a filter element according to  claim 56 , wherein the step of preparing a plurality of upstanding pleats includes forming the upstanding pleats With first and second pleat legs of different height, wherein the height of the first pleat leg is less than the height of the second pleat leg.  
   
   
       60 . A method of forming a filter element according to  claim 56 , wherein the step of preparing a plurality of upstanding pleats includes joining the first pleat leg of one pleat to the second pleat leg of a preceding pleat with a medial pleat section that includes at least one medial pleat segment.  
   
   
       61 . A method of forming a filter element according to  claim 56 , wherein the step of preparing a plurality of upstanding pleats includes joining the first pleat leg of one pleat to the second pleat leg of a preceding pleat with a medial pleat section that includes two medial pleat segments.  
   
   
       62 . A method of forming a filter element according to  claim 56 , wherein the step of preparing a plurality of upstanding pleats includes joining the first pleat leg of one pleat to the second pleat leg of a preceding pleat with a medial pleat section that includes two medial pleat segments of equal length.  
   
   
       63 . A method of forming a filter element according to  claim 56 , wherein the step of preparing a plurality of upstanding pleats includes joining the first pleat leg of one pleat to the second pleat leg of a preceding pleat with a medial pleat section that includes two medial pleat segments of different length.  
   
   
       64 . A method of forming a filter element according to  claim 56 , wherein the step of preparing a plurality of upstanding pleats includes joining the first pleat leg of one pleat to the second pleat leg of a preceding pleat with a medial pleat section having a length that is less than the height of the preceding pleat leg.  
   
   
       65 . A method of forming a filter element according to  claim 56 , wherein the step of preparing a plurality of upstanding pleats includes joining the first pleat leg of one pleat to the second pleat leg of a preceding pleat with a medial pleat section having a length that is about half the height of the preceding pleat leg.