Abstract:
A filter element has filter media supported by a filter frame having differential channel depth receiving initially flowable sealing material. The filter frame has a widened mouth for receiving and funneling sealing material. A filter frame is provided with leading and trailing edge construction ensuring proper installation orientation. A filter frame is provided with removal assist construction for service personnel.

Description:
BACKGROUND AND SUMMARY 
     The invention relates to filter elements and improved sealing therefor. 
     A filter element includes filter media for passing fluid flow therethrough from an upstream side to a downstream side. A filter frame typically circumscribes the filter media for supporting the filter media in a housing. Sealing material is provided between the filter media and the filter frame and provides a seal therebetween blocking bypass of fluid, including contaminates, around the filter media from the upstream side to the downstream side. The filter frame is sealed to the housing, e.g. by a gasket, to also block bypass flow in the housing. 
     The present invention arose during continuing development efforts directed toward filter element sealing technology. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a filter element constructed in accordance with the invention. 
         FIG. 2  is a view of the filter media of  FIG. 1  prior to insertion into the filter frame. 
         FIG. 3  is a perspective view of the filter media of  FIGS. 1 and 2  during insertion into the filter frame. 
         FIG. 4  is a perspective view of a filter frame. 
         FIG. 5  is a sectional view taken along line  5 - 5  of  FIG. 4 . 
         FIG. 6  is a sectional view taken along line  6 - 6  of  FIG. 4 . 
         FIG. 7  is a sectional view of a portion of first and second filter elements in a housing. 
         FIG. 8  is an exploded perspective view of the lower filter element of  FIG. 7 . 
         FIG. 9  is a sectional view of a portion of  FIG. 7  illustrating insertion of a pull tab. 
         FIG. 10  is like  FIG. 9  and shows the construction after insertion of the pull tab. 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 1-3  show a filter element  20  including filter media  22  for passing fluid (e.g. air, liquid, or other fluid) flow therethrough as shown at arrows  24 ,  26 , from an upstream side  28  to a downstream side  30 . A filter frame  32  circumscribes filter media  22  for supporting the filter media in a housing such as  34 ,  FIG. 7 . Sealing material  36  between filter media  22  and filter frame  32  provides a seal therebetween blocking bypass of fluid around the filter media from the upstream side to the downstream side, all as is known. 
     Filter frame  32 ,  FIGS. 4-6 , has a channel  38  receiving the sealing material therein in initially flowable form flowing into contact with filter media  22  and filter frame  32  and forming seal  36  therebetween. Examples of sealing material include foamed hot melt, as known in the art, which may include polymers including polyamide, polyester, polyurethane. The sealing material is introduced by pouring or the like into channel  38 , and then solidifies to form a seal. Channel  38  has a first depth channel section  40 ,  FIGS. 4 ,  5 , of a first channel depth receiving the sealing material, and a second channel section  42 ,  FIGS. 4 ,  6 , of a second channel depth receiving the sealing material. The noted second channel depth,  FIG. 6 , is greater than the noted first channel depth,  FIG. 5 . 
     Fluid flow through filter media  22  is along an axial flow direction, arrows  24 ,  26 . Filter frame  32  extends laterally along a lateral direction relative to the noted axial direction and circumscribes the filter media. Each of the noted first and second channel depths extends axially. Second channel section  42 ,  FIG. 6 , has a greater axial depth than first channel section  40 ,  FIG. 5 . In one embodiment, filter media  22  is pleated filter media pleated along a plurality of axially extending bend lines  44 . As shown in U.S. Pat. No. 6,375,700, incorporated herein by reference, the filter media has a plurality of wall segments extending in serpentine manner between the bend lines, the wall segments extending axially between upstream and downstream ends  28  and  30 , the wall segments defining axial flow channels therebetween, the upstream ends of the wall segments being alternately sealed to each other to define a first set of flow channels having open upstream ends, and a second set of flow channels interdigitated with the first set of flow channels and having closed upstream ends, the downstream ends of the wall segments being alternately sealed to each other such that the first set of flow channels have closed downstream ends, and the second set of flow channels have open downstream ends, such that fluid to be filtered flows substantially directly axially,  24 ,  26 , through the filter media, through the open upstream ends of the first set of flow channels then through the wall segments then through the open downstream ends of the second set of flow channels. First channel section  40  spans along a first lateral direction  46 ,  FIG. 4 , across a plurality of the noted axially extending bend lines  44  of the pleats at one of the upstream and downstream ends, e.g. at downstream end  30 . Second channel section  42  spans along a second lateral direction  48 ,  FIG. 4 , along a given wall segment at the noted one of the upstream and downstream ends, e.g. downstream end  30 . First channel section  40  along the noted first channel depth extends axially beyond the downstream end of the pleated filter media to a first axial extension  41  therebeyond. Second channel section  42  along the noted second channel depth extends axially beyond the downstream end of the pleated filter media to a second axial extension  43  therebeyond. The noted second axial extension  43  of the second channel section  42 ,  FIG. 6 , is longer than the noted first axial extension  41  of the first channel section  40 ,  FIG. 5 . 
     Channel  38 ,  FIGS. 4-6 , has an inner perimeter  50  and an outer perimeter  52 . Outer perimeter  52  is transversely spaced outwardly of inner perimeter  50  by a transverse gap  54  therebetween. Transverse gap  54  receives the sealing material in its initially flowable form. First channel section  40  has first and second walls  56  and  58  spaced along transverse direction  48  by transverse width  54  therebetween. Second channel section  42  has third and fourth walls  60  and  62  transversely spaced along transverse direction  46  by transverse width  64  therebetween. Transverse width  64  is less than transverse width  54 . First channel section  40  has a lesser axial depth and a greater transverse width than the axial depth and transverse width of second channel section  42 . 
     Channel  38  has an entry section  66 ,  FIG. 6 , and a depth section  68 . Entry section  66  includes sidewall  62  extending from depth section  68 . Sidewall  62  has a guide surface  70  extending along a diverging taper providing a widened mouth  72  for initially receiving the sealing material in flowable form and funneling the sealing material to depth section  68 . Depth section  68  extends axially downwardly. Guide surface  70  of sidewall  62  extends obliquely along an oblique direction relative to the noted axial direction. Depth section  68  has the noted sidewalls  62  and  60  transversely spaced by a transverse gap therebetween. Wall  62  has a greater axial height than wall  60 . The top of wall  62  extends axially upwardly beyond the top of wall  60 . Guide surface  70  extends upwardly and obliquely from the top of wall  62 . Channel  38  has the noted first channel section  40  of a first channel depth receiving the sealing material, and the noted second channel section  42  of a second channel depth receiving the sealing material, the second channel depth being greater than the first channel depth, each of the first and second channel depths extending axially, and the second channel section  42  having a greater axial depth than the first channel section  40 . In some embodiments, filter media  22  has a seal bead  74 ,  FIG. 2 , formed therealong extending transversely across the noted pleat bend lines, as is known. The seal bead is formed along the filter media prior to insertion of the filter media into filter frame  32 . Upon insertion of filter media  22  into filter frame  32 , the seal bead  74  extends laterally along the filter media proximate channel  38 . Upon pouring of the flowable sealing material into the filter frame, such sealing material, as it solidifies, bonds with seal bead  74 . 
       FIG. 7  shows filter element  20  in housing  34 , and a second filter element  76  in the housing downstream of first filter element  20 . In one embodiment, first filter element  20  is a primary or main filter element, and filter element  76  is a secondary or safety filter element. Filter element  76  includes filter media  78 ,  FIG. 8 , which may be pleated filter media, foam material, or any other filter media, for passing fluid flow therethrough as shown at arrows  24 ,  26  from an upstream side  80  to a downstream side  82 . A filter frame  84  circumscribes filter media  78  for supporting the filter media in a housing such as  34 . Filter frame  84  is axially insertable into the housing, e.g. axially downwardly in  FIG. 7 . Filter frame  84  has a leading edge  86  and a trailing edge  88  which are laterally offset from one another, for example as shown at lateral offset  90  in  FIG. 10 , such that filter frame  84  can be fully axially inserted into housing  34  only with leading edge  86  first, to ensure proper installation orientation of filter frame  84 , and prevent unintended reverse orientation of filter frame  84  in housing  34 . The noted lateral offset coordinates with housing sidewall tapered ramp surface  92  to provide the noted installation integrity and one-way-only fit for proper orientation. Trailing edge  88  of filter frame  84  is transversely outward of leading edge  86  of the filter frame relative to filter media  80 . 
     Filter frame  84 ,  FIGS. 7 ,  9 ,  10 , has a resiliently compressible seal  94 , e.g. an elastomeric seal, e.g. an O-ring, at leading edge  86 . Housing  34  has an axially extending sidewall  96  which is laterally outward of filter frame  84 . Sidewall  96  has tapered ramp surface  92  extending axially and inwardly towards a sealing surface  98  which extends axially downwardly therefrom. Seal  94  has an uncompressed state,  FIGS. 9 ,  10 , upon introduction into housing  34  at ramp surface  92  of sidewall  96 . Seal  94  has a compressed state,  FIG. 7 , engaging sealing surface  98  of sidewall  96  upon axial insertion of filter frame  84  into housing  34  in the noted proper installation orientation. Filter frame  84  has first and second axially spaced shoulders  100  and  102  defining an axial gap therebetween receiving seal  94 . 
     Filter frame  84 ,  FIGS. 7-10 , is axially insertable into housing  34  with leading edge  86  first. Trailing edge  88  has at least one and preferably two pull tabs  104 ,  106 ,  FIG. 8 , for assisting removal of filter element  76  from housing  34  upon gripping of the pull tab by service personnel. Pull tabs  104 ,  106  are snap-fit mounted to trailing edge  88  of filter frame  84 . Each pull tab is an L-shaped member having first and second legs, e.g. legs  108 ,  110  meeting at a junction  112  at trailing edge  88 . Leg  108  extends axially from junction  112  toward leading edge  86 . Leg  110  extends laterally from junction  112  and into the path of fluid flow through filter media  80 . Leg  108  has an angled snap-fit barb  114  which is pushed axially downwardly through slot or opening  116  of the filter frame,  FIG. 9 , to lock the pull tab in place,  FIG. 10 . Filter media  80  is secured in filter frame  84  in any known manner, e.g. by adhesive at  118 . In one preferred embodiment, the adhesive is polyamide hotmelt bonding with the filter frame, including a plastic frame. Alternatively, the sealing techniques described above for filter element  20  may be used for filter element  76 . 
     In the foregoing description, certain terms have been used for brevity, clearness, and understanding. No unnecessary limitations are to be inferred therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes and are intended to be broadly construed. The different configurations, systems, and method steps described herein may be used alone or in combination with other configurations, systems and method steps. It is to be expected that various equivalents, alternatives and modifications are possible within the scope of the appended claims.