Patent Publication Number: US-8540787-B2

Title: Filter element with percussion band

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a division of U.S. patent application Ser. No. 13/743,744, filed Jan. 17, 2013, which is a division of U.S. patent application Ser. No. 13/571,815, filed Aug. 10, 2012, now U.S. Pat. No. 8,357,218, issued Jan. 22, 2013, which is a division of U.S. patent application Ser. No. 13/410,369, filed Mar. 2, 2012, now U.S. Pat. No. 8,241,377, issued Aug. 14, 2012, which is a division of U.S. patent application Ser. No. 12/545,497, filed Aug. 21, 2009, now U.S. Pat. No. 8,128,719, issued Mar. 16, 2012. 
    
    
     BACKGROUND AND SUMMARY 
     The invention relates to filter elements. 
     Filter elements for filtering fluid are known in the prior art including annular filter elements (cylindrical, oval, elliptical, racetrack shaped, and other closed-loop shapes), and including panel filter elements. The filter element typically includes filter media having a border or perimeter having a frame and/or seal therealong. An annular filter element typically includes annular filter media having a hollow interior and extending axially between first and second axial ends, with the first axial end being open and defining an axial flow path therethrough communicating with the hollow interior, and with fluid flowing axially along the axial flow path through the noted open axial end. A panel filter element is typically flat and may have a rectangular shaped perimeter. During servicing, it is not uncommon for service personnel to remove the filter element from its housing and attempt to percussively clean same by striking the perimeter or border of the filter element (e.g. one or both of the axial ends of an annular filter element; e.g. the edge of the perimeter or border of a panel filter element) against an impact surface, to dislodge and shake free containment and dirt. This can damage the filter element including seals, which in turn can open a bypass flow path, defeating the filter function when the filter element is re-installed. 
     The present invention arose during continuing development efforts in the above technology, including directed toward solving the noted problems. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Prior Art 
         FIGS. 1-14  are taken from U.S. Pat. No. 6,902,598, incorporated herein by reference. 
         FIG. 1  is taken from FIG. 1 of the noted incorporated &#39;598 patent. 
         FIG. 2  is taken from FIG. 2 of the &#39;598 patent and is sectional view taken along line  2 - 2  of  FIG. 1   
         FIG. 3  is taken from FIG. 3 of the &#39;598 patent and shows the open axial end of a closed loop pleated media filter element prior to potting of the end cap. 
         FIG. 4  is taken from FIG. 4 of the &#39;598 patent and shows the open axial end of the filter element of  FIG. 3  after potting of the end cap. 
         FIG. 5  is taken from FIG. 5 of the &#39;598 patent and is a view of a mold for molding an end cap onto pleated filter media of a filter element. 
         FIG. 6  is taken from FIG. 6 of the &#39;598 patent and is a view like a portion of  FIG. 2  and shows an alternate embodiment. 
         FIG. 7  is taken from FIG. 7 of the &#39;598 patent and is like  FIG. 2  and shows the invention of the &#39;598 patent. 
         FIG. 8  is taken from FIG. 8 of the &#39;598 patent and is like  FIG. 3  and shows the invention of the &#39;598 patent. 
         FIG. 9  is taken from FIG. 9 of the &#39;598 patent and is like  FIG. 4  and shows the invention of the &#39;598 patent. 
         FIG. 10  is taken from FIG. 10 of the &#39;598 patent and is like  FIG. 5  and shows the invention of the &#39;598 patent. 
         FIG. 11  is taken from FIG. 11 of the &#39;598 patent and is like  FIG. 6  and shows the invention of the &#39;598 patent. 
         FIG. 12  is taken from FIG. 12 of the &#39;598 patent and is like  FIG. 7  and shows a further embodiment. 
         FIG. 13  is taken from FIG. 13 of the &#39;598 patent and is like  FIG. 7  and shows a further embodiment. 
         FIG. 14  is taken from FIG. 14 of the &#39;598 patent and is like  FIG. 9  and shows a further embodiment. 
       Present Invention 
         FIG. 15  is like a portion of  FIGS. 4 and 9  and shows the present invention. 
         FIG. 16  is like  FIG. 15  and shows a further embodiment. 
         FIG. 17  is like a portion of  FIGS. 2 ,  6 ,  7 ,  11 ,  12 ,  13  and shows the present invention. 
         FIG. 18  is an end view partially cutaway of the construction of  FIG. 17 . 
         FIG. 19  is like  FIG. 15  and shows a further embodiment. 
         FIG. 20  is like  FIG. 19  and shows a further embodiment. 
         FIG. 21  is like  FIG. 20  and shows a further embodiment. 
         FIG. 22  is like  FIG. 17  and shows a further embodiment. 
         FIG. 23  is an end view partially cutaway of the construction of  FIG. 22 . 
         FIG. 24  is like  FIG. 16  and shows a further embodiment. 
         FIG. 25  is like  FIG. 22  and shows a further embodiment. 
         FIG. 26  is a perspective view of a component for use in a filter element in accordance with the invention. 
         FIG. 27  is a perspective view of a partially assembled filter including the component of  FIG. 26 . 
         FIG. 28  is like  FIG. 26  and shows a further embodiment. 
         FIG. 29  is a perspective view partially cutaway of a filter element incorporating the component of  FIG. 28 . 
         FIG. 30  is a like  FIG. 25  and shows a further embodiment. 
         FIG. 31  is an end view partially cutaway of the construction of  FIG. 30 . 
         FIG. 32  is a perspective view showing a further embodiment. 
         FIG. 33  is an enlarged view of a portion of  FIG. 32 . 
         FIG. 34  is a perspective view showing a further embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Prior Art 
     The following description of  FIGS. 1-14  is taken from incorporated U.S. Pat. No. 6,902,598. The &#39;598 patent incorporates U.S. Pat. Nos. 6,149,700, 6,261,334, 6,391,076, 6,398,832, which are also all incorporated herein by reference. 
       FIGS. 1 and 2  show a filter  20  including a filter element  22  contained within a housing  24 . Filter element  22  is provided by pleated filter media  26 ,  FIG. 2 , having a plurality of pleats  28 ,  FIGS. 3 ,  4 , in a closed loop, typically an annulus, having an outer perimeter  30  defined by a plurality of outer pleat tips  32 , and an inner perimeter  34  defined by a plurality of inner pleat tips  36 . The annular closed loop has a hollow interior  38  extending along an axis  40 . Housing  24  is typically cylindrical and is provided by housing sections  42  and  44  mounted to each other in conventional manner such as by overcenter spring clip type clamps such as  46 , or in other suitable manner. The housing has an inlet  50  admitting inlet fluid, such as air or liquid, radially and/or tangentially into annular space  52  within the housing around filter element  22 . Alternatively, the inlet may be at an axial end of the housing, for example as in incorporated U.S. Pat. No. 6,391,076. The housing may include an interior dam or deflection surface  54  for blocking direct impact against filter element  22  and/or for directing flow, for example in a spiral or toroidal pattern. The fluid flows laterally or radially inwardly through filter media  26  into hollow interior  38 , and then the clean fluid flows axially rightwardly in  FIG. 2  in hollow interior  38  along flow passage  56  as shown at arrows  58 ,  59 . Alternatively or additionally, the fluid may flow axially through the filter media as in the noted incorporated &#39;076 patent. 
     Flow passage  56  extending along axis  40  circumscribes hollow interior  38  and has a flow perimeter  60  greater than inner perimeter  34  defined by inner pleat tips  36 , as described in the incorporated &#39;700 patent. Flow perimeter  60  is less than outer perimeter  30  defined by outer pleat tips  32 . Inner perimeter  34  defines and bounds a first cross-sectional area. Flow perimeter  60  defines and bounds a second cross-sectional area. The second cross-sectional area is greater than the first cross-sectional area. Outer perimeter  30  defines and bounds a third cross-sectional area. The second cross-sectional area is less than the third cross-sectional area. Filter element  22  has first and second axial ends  62  and  64 . Axial end  62  is open and provides axial flow passage  56  therethrough. An end cap  66  of soft resilient compressible material, such as foamed potted urethane, axially abuts the axial ends  68  of the pleats. End cap  66  has an inner perimeter  70  greater than inner perimeter  34  defined by inner pleat tips  36 . End cap  66  partially covers the axial ends  68  of the pleats such that the laterally outward portions  72  of the axial ends  68  of the pleats  28  are covered by end cap  66  but not the laterally inward portions  74  of the axial ends  68  of the pleats, such that the laterally inward portions  74  of the axial ends of the pleats are uncovered and exposed at axial end  62  of filter element  22 ,  FIG. 4 . 
     In one embodiment, second axial end  64  of filter element  22  is closed. A second end cap  76 ,  FIG. 2 , of soft compressible resilient material, such as foamed potted urethane, is provided at second end  64  of filter element  22  and completely covers the axial ends  78  of the pleats including the outer pleat tips  32  and the inner pleat tips  36  at axial end  64 . End cap  76  also includes a central section  80  spanning and completely covering hollow interior  38  of filter element  22  at axial end  64  of the filter element. Housing section  44  includes an annular interior sidewall  82  extending partially axially into the housing to locate and retain filter element  22  at axial end  64 . In other embodiments, central section  80  of end cap  76  is omitted, and a portion of housing  44  extends into hollow interior  38  of filter element  22  to close axial end  64  of the filter element and to position axial end  64  of the filter element within the housing. Further embodiments are shown in the noted incorporated &#39;076 patent. End cap  76  includes an annular ridge  84  engaging axial end wall  85  of housing section  44  and slightly axially compressed thereagainst to further aid in retention of filter element  22  within the housing and to accommodate axial tolerances. End cap  66  also includes an annular ridge  86  engaging axial end wall  88  of housing section  42  and slightly radially compressed thereagainst to aid in retaining filter element  22  within the housing and to accommodate axial tolerances and also to provide an axial seal to prevent bypass of dirty air from annular chamber  52  around axial end  62  of the filter element. Axial end wall  88  of housing section  42  has an outlet flow tube  90  extending therethrough. In addition to or alternatively to the axial seal at  86 , end cap  66  provides a radial seal at  70  against outlet flow tube  90 . 
     End cap  66  has a sidewall  92  extending axially away from axial ends  68  of pleats  28  at axial end  62  of filter element  22 . The sidewall has the noted inner perimeter  70 , and has an outer perimeter  94 . As noted above, inner perimeter  70  of sidewall  92  is greater than inner perimeter  34  of filter element  22  defined by inner pleat tips  36 . Inner perimeter  70  of sidewall  92  of end cap  66  is less than outer perimeter  30  of filter element  22  defined by outer pleat tips  32 . Outer perimeter  94  of sidewall  92  of end cap  66  is greater than outer perimeter  30  of filter element  22  defined by outer pleat tips  32 . Flow tube  90  has an inner section  96  axially facing the axial ends  68  of pleats  28 . Inner section  96  of flow tube  90  has an inner perimeter  98  and an outer perimeter  100 . Outer perimeter  100  is greater than inner perimeter  70  of sidewall  92  of end cap  66 , such that as filter element  22  at end cap  66  is axially slid rightwardly over inner section  96  of flow tube  90 , end cap  66  is radially compressed to expand inner perimeter  70  along outer sidewall  100  of flow tube inner section  96  to effect the noted radial seal. Inner perimeter  70  of end cap  66  is preferably stepped, as shown at 71 in FIG. 8 of the noted incorporated &#39;700 patent, to have slightly progressively decreasing diameters from right to left as viewed therein, to receive and guide inner section  96  of flow tube  90  therealong and increase radial sealing pressure. End cap  66  circumscribes inner section  96  of flow tube  90  and bears radially thereagainst at  70  in sealing relation to form the noted radial seal thereat. End wall  88  of housing section  42  axially faces axial ends  68  of pleats  28 , and end cap  66  also bears axially against end wall  88  in sealing relation at  86  to form the noted axial seal thereat. 
     An outer liner  102 ,  FIG. 2 , provided by an expanded wire mesh or screen or perforated metal or plastic, circumscribes filter element  22  along outer pleat tips  32  and has an axial end section  104  extending axially beyond the axial ends  68  of pleats  28 . An inner liner may also be provided at inner perimeter  34  along inner pleat tips  36 . As above described, flow tube  90  communicates with hollow interior  38  of the filter element along flow passage  56  and extends axially from the axial end of the filter element. End cap  66  at the axial end of the filter element bears radially between and is radially compressed between and against section  104  of outer liner  102  and inner section  96  of flow tube  90 . Outer liner  102  extends axially at  104  into end cap  66  and is potted therein during the molding process, as described in the incorporated &#39;700 patent. As noted above, sidewall  92  of end cap  66  extends axially away from the axial ends  68  of pleats  28  at the axial end of the filter element. Outer perimeter  94  of the end cap sidewall circumscribes outer liner section  104 . The filter element may also include an inner liner  103 ,  FIG. 5 , along inner pleat tips  36 . 
     Pleats  28  have pairs of walls defining axially extending interior channels  106 ,  FIG. 3 , and also as shown in FIG. 7 of the incorporated &#39;700 patent, and axially extending exterior channels  108 . The walls of the pleats defining the exterior channels  108  are sealed to each other near axial end  62  of the filter element by heat seal bonding along glue strips, also known as hot melt, such as  110 , and as shown in the incorporated &#39;700 patent at FIGS. 4-6, 9, and for example as disclosed in U.S. Pat. No. 5,106,397, incorporated herein by reference. This prevents bypass of dirty air around the axial ends of the pleats at inner exposed portions  74 . Fluid such as air flowing radially inwardly through the filter media as shown at  112 , and as shown in the incorporated &#39;700 patent at FIG. 4, or alternatively flowing axially as shown in the incorporated &#39;076 patent at FIGS. 15, 16 thereof, must flow through the sidewalls of pleats  28  before such fluid can flow axially through hollow interior  40  as shown at arrow  58  or axially through the inward portions  74  of the axial ends  68  of the pleats as shown at arrow  59 . Some of such air can flow axially rightwardly as shown at arrow  59  axially along interior channels  106 , and the balance of the air continues radially inwardly as shown at arrow  114 , and as shown in the incorporated &#39;700 patent in FIG. 4, and then flows axially as shown at arrow  58 . The axial ends of exterior channels  108  at the axial end of the filter element are blocked by the noted hot melt seal bonding along adhesive strips  110 . Fluid flowing through the filter element is forced to pass from exterior channels  108  to interior channels  106 . FIGS. 6 and 9 of the incorporated &#39;700 patent show the seal bonded adhesive  110  extending in exterior channels  108  all the way from inner pleat tips  36  to outer pleat tips  32  as idealized. If the seal bond does not extend all the way from inner pleat tip  36  to outer pleat tip  32 , then the shape of the interior channel  106  at outer pleat tip  32  will generally be more rounded and the walls of pleats  28  forming exterior channels  108  at outer pleat tips  32  will usually be closer together. In an alternative, the adhesive seal bond in exterior channels  108  may extend from inner pleat tips  36  only partially towards outer pleat tips  32 , and the outer portions of exterior channels  108  are blocked at the axial end of the filter element at end cap  66 . During the molding potting process, the liquid castable material into which the pleated filter media is dipped will foam up a short distance axially into the channels between the pleats, as shown in the incorporated &#39;700 patent at inner section 116 in FIGS. 4, 8, 9 thereof, of the end cap which has migrated a distance 118, FIG. 4 of the incorporated &#39;700 patent, between the pleats. The spacing of glue strips  110  on the pleats from the axial ends  68  of the pleats may be adjusted as desired in standard glue seal strip applicator machines. Preferably, glue seal strips  110  are spaced from axial ends  68  of the pleats by a small distance  118  to enable a slight deformation of the axial ends  68  of the pleats by a dam in the mold during the molding potting process, to keep the liquid castable material of the end cap from flowing radially inwardly into inner portions  74  of the pleat ends which are desired to be exposed, which molding process and dam are disclosed in the noted &#39;700 patent, and noted hereinafter. Alternatively, seal glue strips  110  may be applied at axial ends  68  of the pleats, without gap  118  therebetween. 
       FIG. 5  shows a mold  120  for molding or potting end cap  66  onto pleated filter media  26  of the filter element. The mold has a trough  122  extending along an annular first perimeter and holding liquid castable material, such as urethane, therein into which axial ends  68  of pleats  28  are dipped. The mold has an insert  124  with an upstanding dam  126  extending along a second annular perimeter circumscribed by the noted annular perimeter of trough  122 . Dam  126  engages axial ends  68  of the pleats between outer pleat tips  32  and inner pleat tips  36  and impedes flow of liquid castable material laterally radially inwardly towards inner pleat tips  36 . Trough  122  partially spans axial ends  68  of the pleats such that the laterally outward portions  72  of the axial ends of the pleats are covered by liquid castable material but not the laterally inward portions  74  of the pleats, such that laterally outward portions  72  of the axial ends  68  of the pleats are covered by end cap  66 , and the laterally inward portions  74  of the axial ends  68  of the pleats are uncovered by end cap  66  and are left exposed. It is preferred that the pleated filter media be dipped into the liquid castable material in the mold by lowering the pleated filter media downwardly until axial ends  68  of the pleats are engaged by dam  126 , and then pushing the pleated filter media further slightly downwardly against the dam such that the dam slightly deforms axial ends  68  of the pleats at such engagement point which in turn pushes the pleat sidewalls forming the noted channels slightly laterally to further block the channels and further impede flow of liquid castable material laterally inwardly towards inner pleat tips  36 . Trough  122  is bounded by an outer perimeter  126  and an inner perimeter  128 . Outer perimeter  126  of trough  122  is greater than outer perimeter  30  of the filter element defined by outer pleat tips  32 . Inner perimeter  128  of trough  122  is less than outer perimeter  30  of the filter element. Inner perimeter  128  of trough  122  is greater than inner perimeter  34  of the filter element defined by inner pleat tips  36 . The noted second perimeter of the mold at annular dam  126  is less than or equal to inner perimeter  128  of trough  122 . 
     As noted, the method for molding end cap  66  onto pleated filter media  26  involves dipping axial ends  68  of the pleats into liquid castable material in trough  122  of mold  120 , and engaging axial ends  68  of the pleats against dam  126  at a location between outer pleat tips  32  and inner pleat tips  36  such that darn  126  impedes flow of the liquid castable material laterally inwardly towards inner pleat tips  36 . Trough  122  is provided and aligned such that it partially spans axial ends  68  of the pleats such that the laterally outward portions  72  of the axial ends of the pleats are covered by the liquid castable material during dipping, but not the laterally inward portions  74  of the axial ends of the pleats. Further in accordance with the described method, laterally inward flow of the liquid castable material is impeded along the axial ends of the pleats toward inner pleat tips  36  by providing and aligning dam  126  to engage axial ends  68  of the pleats between outer pleat tips  32  and inner pleat tips  36  such that laterally outward portions  72  of the axial ends of the pleats are covered by end cap  66 , and laterally inward portions  74  of the axial ends of the pleats are uncovered by end cap  66  and are left exposed. Trough  122  and filter element  22  are aligned during the noted dipping such that outer perimeter  126  of trough  122  circumscribes outer perimeter  30  of the filter element defined by outer pleat tips  32 , and inner perimeter  128  of trough  122  circumscribes inner perimeter  26  of the filter element defined by inner pleat tips  36 . 
       FIG. 6  shows an alternate embodiment wherein outlet flow tube  90   a  has an outer section  90   b  of reduced diameter to accommodate engine compartment size and location requirements, yet maintaining an increased diameter inner section  90   c  maintaining the increased diameter and perimeter flow passage  56  including axial fluid flow at  58  and the extra axial fluid flow at  59 ,  FIGS. 2 and 6 . The spacing of axial end wall  88  of housing section  42  from axial ends  68  of the filter media pleats provides a plenum  130  accommodating the extra flow and reducing restriction. 
     The described filter construction was developed for air filters, though may be used for other fluids such as liquid. In the disclosed embodiment, fluid to be filtered flows laterally inwardly through the filter media from the outer perimeter to the inner perimeter and then flows axially in the hollow interior, such that flow passage  56  is an outlet flow passage. Alternatively, fluid to be filtered may flow axially in hollow interior  38  and then flow laterally outwardly through the filter media from the inner perimeter to the outer perimeter, in which case flow passage  56  is the inlet flow passage. In another alternative, fluid flow to or from axial end  64  of the filter element and through the media may be axial or a combination of axial and radial, for example as in the noted incorporated &#39;076 patent. In other alternatives, metal end caps are used instead of urethane end caps, or various combinations of materials are used for the end caps. In further alternatives, outer section  90   b ,  FIG. 7 , of the flow tube has a larger inner diameter than inner section  90   c.    
     During further development, it has been found that there are some applications where enhanced structural integrity is desired in the end cap area at  66 , for example wet conditions, heavy load conditions, vibration, and the like. There are also circumstances where cost reduction is desired. There are also circumstances where even further sealing is desired. 
       FIGS. 7-11  are like  FIGS. 2-6 , respectively, and use like references numerals where appropriate to facilitate understanding. Filter element  22  is provided by pleated filter media  26  having a plurality of pleats  28  in a closed loop having an outer perimeter  30  defined by a plurality of outer pleat tips  32 , and an inner perimeter  34  defined by a plurality of inner pleat tips  36 , and having a hollow interior  38  extending along axis  40 . Fluid flows axially in hollow interior  38  as shown at arrow  58 . The filter element has first and second axial ends  62  and  64 . The first axial end is open and provides an axial flow passage  57  therethrough along axis  40  communicating with hollow interior  38 . A resiliently compressible end cap  200  at the open axial end covers inner and outer pleat tips  36  and  32  and spans radially along axial ends  68  of the pleats between inner and outer perimeters  34  and  30 . A flow tube  202  communicates with hollow interior  38  and extends along axial flow passage  57  and engages end cap  200 . Flow tube  202  at engagement  204  with end cap  200  has an inner perimeter  206  greater than inner perimeter  34  defined by inner pleat tips  36 . Inner perimeter  206  of flow tube  202  at engagement  204  with end cap  200  is less than outer perimeter  30  defined by outer pleat tips  32 . 
     End cap  200  has a first section  208  extending radially inwardly from outer perimeter  30  defined by outer pleat tips  32 , and has a second section  210  extending radially outwardly from inner perimeter  34  defined by inner pleat tips  36 . First and second sections  208  and  210  meet at a junction defining a step at  204  facing radially inwardly toward and engaging flow tube  202 . The step at  204  has a first axial length. Flow tube  202  has an inner tubular portion  212  extending axially along step  204 . Tubular portion  212  has an inner axial end  214  facing the first axial end of the filter element at axial ends  68  of the pleats and separated therefrom by section  210  of end cap  200 . Flow tube  202  has a flange portion  216  extending radially from tubular portion  212  and facing the first axial end of the filter element at axial ends  68  of the pleats and axially spaced from inner axial end  214  of tubular portion  212  by a second axial length which is less than the noted first axial length, to thus provide axial compression of end cap  200  including at axial seal region  218 . End cap  200  has a first axial thickness at first section  208  at outer perimeter  30 , a second axial thickness at first section  208  at step  204 , a third axial thickness at second section  210  at step  204 , and a fourth axial thickness at second section  210  at inner perimeter  34 . The noted second axial thickness is greater than the noted third axial thickness. The noted first axial thickness is greater than the noted fourth axial thickness. The noted first axial thickness is less than the noted second axial thickness. The noted third and fourth axial thicknesses are substantially the same. 
     In one embodiment, the filter element includes in combination the noted second end cap  76  at the second axial end  64  of the filter element at axial ends  78  of the pleats and covering inner and outer pleat tips  36  and  32  and spanning radially between inner and outer perimeters  34  and  30 , and also spanning hollow interior  38  and closing the second axial end of the filter element. The filter element is preferably contained in the noted housing having an end wall  220  facing the first axial end of the filter element. Flow tube  202  is part of end wall  220 . 
     Flow tube  202  engages end cap  200  at first, second and third engagement seals  218 ,  222  and  224 , respectively, to provide triple sealing of end cap  200  to flow tube  202 . Seals  218  and  224  are axial seals, and seal  222  is a radial seal. First inner portion  212  of flow tube  202  extends axially along step  204  and engages the step to form the noted second radial seal  222 . Tubular portion  212  has the noted inner axial end  214  axially engaging end cap  200  at the noted second section  210  and forming the noted third axial seal  224 . Flow tube  202  has the noted flange portion  216  extending radially from tubular  212  and axially spaced outwardly of inner axial end  214  and axially engaging end cap  200  at first section  208  and providing the noted first axial seal  218 . Second radial seal  222  is axially between first and third axial seals  218  and  224 . 
       FIG. 10  shows a mold  120  for molding or potting end cap  200  onto pleated filter media  26  of the filter element. The mold has a trough  122  as above. The mold has an insert  230  similar to insert  124  but with upstanding darn  232  at inner pleat tips  36  at inner perimeter  34 . 
       FIG. 11  shows an alternate embodiment wherein outlet flow tube  202   a  has an outer section  201   a  of reduced diameter to accommodate engine compartment size and location requirements, yet maintaining an increased inner diameter section  203   a , as in  FIG. 6 . The spacing of axial end wall  220  of the housing from axial ends  68  of the filter media pleats provides the noted plenum  130 . End cap  200   a  has the noted first and second sections  208   a  and  210   a . End cap  200   a  covers the inner and outer pleat tips  36  and  32  and spans radially between the inner and outer perimeters  34  and  30 . The end cap provides the noted triple sealing at axial seals  218   a  and  224   a  and at radial seal  222   a.    
     As shown in comparing  FIGS. 3 ,  4 ,  8 ,  9 , the present construction seals the axial ends  68  of the pleats solely with urethane end cap  200 , or  200   a , and eliminates reliance upon hot melt  110  for sealing purposes. This eliminates the adhesive component in the design of  FIGS. 3 ,  4 , and simplifies the production process, reducing cost. In the present construction of  FIGS. 8 ,  9 , the axial ends  68  of the pleats  28  are sealed with the same urethane  200 , or  200   a , used to pot the element, rather than a combination of hot melt  110  and urethane  66  as in  FIGS. 3 ,  4 . The present construction also eliminates reliance upon the interface between the glue  110 , the filter media of the pleats  28 , and the urethane  66  to prevent contaminants from passing to the clean side of the filter. The present construction further facilitates concentricity of the closed loop configuration. The present construction further enhances structural integrity, particularly in wet conditions, heavy load conditions, and vibration conditions. 
       FIG. 12  shows a further embodiment and uses like reference numerals from above where appropriate to facilitate understanding. End cap  200   b  has first section  240  extending radially inwardly from the outer perimeter  30  defined by outer pleat tips  32 , and has a second section  242  extending radially inwardly from first section  240 . First and second sections  240  and  242  meet at a junction defining a step  204   b . Flow tube  202   b  communicates with hollow interior  38  and extends along axial flow passage  57 . Flow tube  202   b  has an inner tubular portion  212   b  extending along step  204   b  and radially engaging the step to form a radial seal  222  therewith. Flow tube  202   b  has the noted flange portion  216  extending radially outwardly from tubular portion  212   b  and axially spaced from first axial end  68  of the filter element by first section  240  of end cap  200   b  therebetween. Flange portion  216  engages first section  240  of end cap  200   b  at engagement point  218   b  to form an axial seal therewith. Tubular portion  212   b  has an inner axial end  244  axially facing first end  68  of the filter element. Second section  242  of end cap  200   b  is axially between inner axial end  244  of tubular portion  212   b  and first axial end  68  of the filter element. Second section  242  of end cap  200   b  extends radially inwardly from first section  240  of the end cap all the way to inner perimeter  34  defined by inner pleat tips  36 . End cap  200   b  covers inner and outer pleat tips  36  and  32  and spans radially between inner and outer perimeters  34  and  30 . Inner axial end  244  of tubular portion  212   b  is axially spaced from second section  242  of end cap  200   b  by an axial gap  246  therebetween. This may be desired in some applications to protect against excessive axial compression or axial crushing. For example, it may be desired to protect the pleat ends at  68  from the line of axial force otherwise provided by the annulus at inner end  244  of the flow tube, with or without adhesive or hot melt  110  between the pleats. 
       FIG. 13  shows a further embodiment and uses like reference numerals from above where appropriate to facilitate understanding. End cap  200   c  has a first section  250  extending radially inwardly from the outer perimeter  30  defined by outer pleat tips  32 , and has a second section  252  extending radially inwardly from first section  250 . First and second sections  250  and  252  meet at a junction defining a step  204   c . Flow tube  202   c  communicates with hollow interior  38  and extends along axial flow passage  57 . Flow tube  202   c  has a tubular portion  212   c  extending axially along step  204   c  and radially engaging the step to form a radial seal therewith. Flow tube  202   c  has flange portion  216  extending radially outwardly from tubular portion  212   c  and axially spaced from first axial end  68  of the filter element by the first section  250  of end cap  200   c  therebetween. Flange portion  216  axially engages first section  250  of end cap  200   c  at engagement point  218   c  to form an axial seal therewith. Tubular portion  212   c  has inner axial end  214  axially facing first end  68  of the filter element. Second section  252  of end cap  200   c  is axially between inner axial end  214  of tubular portion  212   c  and first end  68  of the filter element. Second section  252  of end cap  200   c  extends radially inwardly from first section  250  only partially towards inner perimeter  34  defined by inner pleat tips  36  and does not cover inner pleat tips  36 . This embodiment may be desirable in instances where the additional migration or flow at  59  is desired. This embodiment may also be desirable where additional flow of potting material into the pleat ends and between the wall segments of the pleats is desired. For example, the wider the radial extent of the end cap along axial end  68  of the filter element, the greater the axially leftward migration of the molten potting material into and between the pleats. This may be desirable for enhanced sealing including greater interface area with the adhesive or hot melt  110  between the pleats. Inner axial end  214  of tubular portion  212   c  may axially engage second section  252  of end cap  200   c  as shown in  FIG. 13  to form a second axial seal  224  therewith as in  FIG. 7 . Alternatively, inner axial end  214  may be spaced axially rightwardly of second section  252  of the end cap by an axial gap therebetween as at axial gap  246  in  FIG. 12 . 
       FIG. 14  shows a further embodiment including a filter element  260  including a closed loop filter media member  262  having a hollow interior  264  extending along a given axis  266 , and which may also include an outer prefilter member  268  such as open cell foam. Fluid flows axially in hollow interior  264 . The filter element has first and second axial ends  270  and  271 . First axial end  270  is open and provides an axial flow passage  272  therethrough along axis  266  communicating with hollow interior  264 . A resiliently compressible end cap  274  is provided at first axial end  270 . A flow tube as shown in dashed line at  276  and which is comparable to flow tube  202 , communicates with hollow interior  264  and extends along axial flow passage  272 . Flow tube  276  has a tubular portion  278 , comparable to tubular portion  212 , engaging end cap  274  and forming a seal therewith, comparable to seal  218  and/or  222  and/or  224 . Tubular portion  278  is cylindrical. Filter media member  262  is non-cylindrical. In one embodiment, the filter media member is elliptical, such as oval, racetrack shaped, or the like. End cap  274  has a first section  280  extending radially inwardly from an outer perimeter  282 , and has second section  284  extending radially inwardly from first section  280  to an inner perimeter  286 . First and second sections  280  and  284  are comparable to first and second sections  240  and  242  and to first and second sections  250  and  252 . First and second sections  280  and  284  meet at a junction defining a step  288 , comparable to steps  204 ,  204   b ,  204   c . First section  280  has the noted outer perimeter  282 , and has an inner perimeter  290  at step  288 . Second section  284  has an outer perimeter  292  at step  288 , and has the noted inner perimeter  286  communicating with hollow interior  264 . Outer perimeter  282  of first section  280  is non-cylindrical. Inner perimeter  290  of first section  280  is cylindrical. Step  288  is cylindrical. Outer perimeter  292  of second section  284  is cylindrical. Cylindrical tubular portion  278  engages end cap  274  at cylindrical step  288 , comparable to the above noted engagement of cylindrical portions  212 ,  212   b ,  212   c  with steps  204 ,  204   b ,  204   c . Inner perimeter  286  of second section  284  is non-cylindrical. Filter media member  262  and outer perimeter  282  of first section  280  of end cap  274  are elliptical and have a radially extending major axis (left-right in  FIG. 14 ), and a radially extending minor axis (up/down in  FIG. 14 ). The radial extension of first section  280  of end cap  274  along the major axis between outer perimeter  282  of first section  280  of end cap  274  and step  290  is greater than the radial extension of first section  280  of end cap  274  along the minor axis between outer perimeter  282  of first section  280  of end cap  274  and step  288 . The radial extension of second section  284  of end cap  274  along the minor axis between step  288  and inner perimeter  286  of second section  284  of end cap  274  is greater than the radial extension of the second section  284  of end cap  274  along the major axis between step  288  and inner perimeter  286  of second section  284  of end cap  274 . In the embodiment shown, filter media member  262  is provided by pleated filter media having a plurality of pleats as above in a closed loop having an outer perimeter defined by a plurality of outer pleat tips, comparable to pleat tips  32 , and an inner perimeter defined by a plurality of inner pleat tips, comparable to pleat tips  36 , the loop having the noted hollow interior  264  extending along the noted given axis  266 . Other types of filter media may be used, including non-pleated media. The disclosed elliptical filter design may be used in implementations where it is desired to have an elliptical filter and to maximize the inlet or outlet diameter of the filter or match specifications requiring cylindrical inlet or outlet flow tubes. 
     Present Invention 
       FIGS. 15-31  use like reference numerals from above where appropriate to facilitate understanding. 
       FIG. 15  shows filter element  22  of  FIGS. 1 ,  2 , modified, to be described, for filtering fluid, including annular filter media  26  having a hollow interior  38 ,  FIGS. 2 ,  15 , and extending axially along axis  40  between first and second axial ends  62 ,  64 , the first axial end  62  being open and defining an axial flow path  57 ,  FIG. 7 , therethrough communicating with hollow interior  38 , the fluid flowing axially as shown at  58  along the axial flow path  57  through open axial end  62 . A reinforcement ring  302 ,  FIG. 15 , is provided at at least one of the noted axial ends, e.g. at open axial end  62 , and performs a support function thereat upon attempted percussive cleaning of filter element  22  by service personnel striking the axial end against an impact surface, for example as schematically shown at  304 . Annular filter media  26  has an outer circumference  30  and an inner circumference  34  and extends radially therebetween. As used herein, annular includes circular, elliptical, oval, racetrack-shaped, and other closed-loop shapes. First axial end  62  has an axially facing end face  68  extending radially between inner and outer circumferences  34  and  30 . Reinforcement ring  302  is at at least one of outer circumference  30 , end face  68 , and inner circumference  34 , to be described. In various embodiments, to be described, the reinforcement ring is an annular member at the outer circumference and/or at the end face and/or at the inner circumference and/or at the junction of the end face and the outer circumference and/or at the junction of the end face and the inner circumference. The reinforcement ring may have various cross-sectional shapes such as rectangular or square as shown at  302  in  FIG. 15 , round as shown at  306  in  FIG. 16 , as well as other cross-sectional shapes. 
     End cap  200 ,  FIG. 15 , may extend at section  210  radially inwardly all the way to inner circumference  34 , as in  FIGS. 7 ,  11 ,  12 , or may stop short thereof as in  FIGS. 2 ,  6 ,  13  at end cap  66 . The end cap is a molded member, as described above, and encapsulates the junction of end face  68  and outer circumference  30  and extends radially inwardly along end face  68  at least partially towards inner circumference  34 . Reinforcement ring  302  is encapsulated in end cap  200 . In one embodiment, the reinforcement ring, or at least a portion thereof, is at end face  68  and spaced radially outwardly of inner circumference  34 . 
     In  FIG. 17 , reinforcement ring  306  is an L-shaped member having a first leg  308  along outer circumference  30  and a second leg  310  extending radially inwardly, which leg  310  may extend all the way to inner circumference  34  as shown in  FIG. 17 , or may stop short thereof. Leg  310  may be perforated as shown at perforations  312  in  FIG. 18 , which may be desirable in those embodiments where the end cap does not extend radially inwardly all the way to or past inner circumference  34 , which embodiments provide the noted additional flow at  59 ,  FIGS. 2 ,  6 ,  13 . 
     Filter element  22  may have an outer liner, for example as shown at  102  in  FIGS. 2 ,  7 ,  11 - 13 , which outer liner  102  extends axially along outer circumference  30  and may extend beyond end face  68  as shown at  104 . In  FIG. 19 , outer liner  102  has a reinforcement segment  314  turned radially away from outer circumference  30  and providing the noted reinforcement ring. Reinforcement segment  314  is turned radially inwardly toward inner circumference  34 . In  FIG. 19 , the reinforcement segment  314  is curled in a spiral as shown at  316 . In  FIG. 20 , reinforcement segment  318  is turned radially inwardly toward inner circumference  34  and has a turn-back portion  320  turned back axially toward end face  68 . In  FIG. 21 , reinforcement segment  322  extends from a turn  324  at outer circumference  30  and extends radially inwardly to a termination end  326  pointing toward inner circumference  34 . In an alternative, reinforcement segment  322  may extend radially inwardly all the way to inner circumference  34  as shown in  FIG. 17 , preferably with end cap encapsulation thereof. In  FIGS. 21 and 17 , the reinforcement segment in one embodiment extends from a substantially 90° turn  324  at outer circumference  30  then substantially rectilinearly to termination end  326 . The reinforcement segment may be permeable as shown at  312  in  FIG. 18 . In  FIG. 22 , the reinforcement ring  330  includes an outer axial segment  332  along outer circumference  30 , a radial segment  334  extending radially inwardly from outer circumference  30  to inner circumference  34 , and an inner axial segment  336  extending axially along inner circumference  34 . Reinforcement ring  330  may be a separate member or may be an extension of outer liner  102 . In a further embodiment, reinforcement ring  330  may be an extension of inner liner  338 . In a further embodiment, reinforcement ring  330  at radial extension segment  334 , whether provided by a separate member or by an extension of outer liner  102  or by an extension of inner liner  338 , may be perforated as shown at perforations  340 ,  FIG. 23 , which may be desirable if end cap  200  is not extended radially inwardly all the way to inner circumference  34 , for example as shown at end cap  66  in  FIGS. 2 ,  6 ,  13 . 
       FIG. 24  shows a mold  342  for molding or potting end cap  200 , or end cap  66 ,  FIG. 2 , onto pleated filter media  26  of the filter element, comparable to mold  120 ,  FIG. 5 . End cap  200  at the noted first axial end  68  has an axial extension portion  344  extending axially along outer circumference  30  including outer liner  102  if provided. Reinforcement ring  346  is at axial extension portion  344  of the end cap. Axial extension portion  344  extends axially to an axial termination end  348 . Reinforcement ring  346  is at termination end  348 . Reinforcement ring  346  is axially spaced from end face  68  in a given axial direction away from axial end  62 . The end cap provides a seal formed by molding material at first axial end  62 , as above noted. Reinforcement ring  346  is a dam blocking flow of molding material therepast in the noted given axial direction. 
     In  FIG. 25 , end cap  200  has an axial extension portion  352  extending axially along outer circumference  30  including outer liner  102  if provided, and has a radial extension portion  354  extending radially inwardly along end face  68 . Reinforcement ring  356  is provided along the exterior of end cap  200 . Reinforcement ring  356  has an axial segment  358  extending axially along the exterior of axial extension portion  352  of the end cap and spaced radially outwardly of outer circumference  30  by the axial extension  352  of the end cap therebetween. Reinforcement ring  356  has a radial segment  360  extending radially along the exterior of radial extension portion  354  of the end cap and spaced axially outwardly of end face  68  by radial extension portion  354  of the end cap therebetween. 
     In  FIGS. 26 ,  27 , the reinforcement ring is an annular ring member  362  having a plurality of spokes  364  extending radially inwardly therefrom to a central hub  366  axially aligned with hollow interior  38 . The spokes at least partially cross end face  68 .  FIG. 27  shows a housing section  368  comparable to housing section  42 ,  FIGS. 1 ,  2 , having an inlet  370  comparable to inlet  50 , and having an outlet  372  comparable to outlet  90 . 
     In  FIGS. 28 ,  29 , reinforcement ring  374  is provided by concentric first and second ring members  376  and  378  at end face  68  and a structural support web comprising a plurality of truncated spokes  380  extending radially between the first and second ring members. Second ring member  378  is at outer circumference  30 , and first ring member  376  is spaced radially inwardly thereof. In the embodiment of  FIGS. 28 ,  29  first ring member  376  is at inner circumference  34 , and reinforcement ring  374  includes a third ring member  382  radially intermediate first and second ring members  376  and  378 . Third ring member  382  has an axial extension  384  extending axially away from end face  68  and axially beyond first and second ring members  376  and  378 . In one embodiment, end cap  66  encapsulates second and third ring members  382  and  378  and the junction of outer circumference  30  and end face  68 . Further in such embodiment, end cap  66  does not encapsulate first ring member  376 , and fluid flows axially along axis  40  between structural support web truncated spokes  380  at a location along end face  68  between first ring member  376  and end cap  66  as shown at arrow  59 , which additional flow is also shown at  59  in  FIGS. 2 ,  6 ,  13 . 
     In  FIGS. 30 ,  31 , the reinforcement ring is replaced by a failure ring  386  at the noted open axial end  62 . Failure ring  386  performs a designated failure function to a failure condition at the open axial end upon attempted percussive cleaning of filter element  22  by service personnel striking open axial end  62  against an impact surface  304 , with the failure condition providing at least one of: a) an indication to service personnel that filter element  22  has been damaged and should not be re-installed; and b) a deformed condition preventing re-installation. Failure ring  386  is at at least one of outer circumference  30 , end face  68  and inner circumference  34 . In one embodiment, the failure condition is selected from the group consisting of fracture, tearing, failure, protruding, re-assembly prevention, and change in shape. In the embodiment of  FIGS. 30 ,  31 , failure ring  386  is an annular fracture disk  388  at end face  68  and spanning from outer circumference  30  at least partially radially inwardly toward inner circumference  34  and having a plurality of tapered radial slots  390 ,  FIG. 31 , tapering to wider widths as the slot extends radially inwardly toward inner circumference  34 . In another embodiment, the noted indication is selected from the group consisting of a color change, a texture change, a smell change, and a chemical release causing a change in a material physical characteristic. In one form of such embodiment, the failure ring includes microcapsules in the molded end cap at the noted open axial end, which microcapsules when ruptured produce one of the noted changes. In one desirable embodiment, the microcapsules rupture to provide a color change from green to red, wherein green indicates good, and red indicates bad or damaged. The fracture indicator may be potted into or adhered to the outside of a urethane end cap. The indicator can be made of a very thin pouch with printing on the surface, and would contain a clear viewing window, which would show the green colored microbeads inside. When the axial end of the filter element at the end cap is hit with an impact force above a designated level, the microbeads would rupture or pop and bleed into the entire viewing area, revealing a red color. This would show the customer that the pleat tip seals of the element may be comprised. The indicator label may have printed instructions telling a customer: do not clean; and red panel means discard the element. The label and indicator would also help customers identify that they are using an original equipment manufacturer product and differentiate same from unauthorized replacement elements. In another example, the failure ring may be provided by a pressure sensitive film containing the microcapsules. For example, a pressure sensitive film produced by Fuji under the trademark PRESSUREX is a Mylar based film that contains a layer of microcapsules. The application of force upon the film causes the microcapsules to rupture, producing an instantaneous and permanent high resolution topographical image of pressure variation across the contact area. The pressure indicating sensor film may be placed between any two surfaces that touch, mate or impact. Pressure can be applied and the film then removed, whereupon the film reveals the pressure distribution profile that occurred between the two surfaces. This is conceptually similar to litmus paper, with the color intensity of the noted pressure indicating sensor film directly related to the amount of pressure applied to it. The greater the pressure, the more intense the color. 
     In the above embodiments, the reinforcement ring is at the open first axial end  62  of the annular filter element. In a further embodiment, a reinforcement ring  392 ,  FIG. 32 , may be provided at the noted second axial end  64 . In further embodiments, two axially distally opposite reinforcement rings  302 ,  392  are provided, as shown in  FIG. 32 . One or both of the rings  302 ,  392  may include or be replaced by a failure ring, which in one embodiment includes the noted microcapsules in a respective molded end cap  66 ,  76  at the respective axial end  62 ,  64 , which microcapsules when ruptured produce the noted change. The failure ring may include an indication, such as shown at failure ring strip  394  in  FIG. 33 , such as “do not clean”, “red panel=discard element”, and so on. 
     The above embodiments show an annular filter element. In another embodiment, the filter element is a panel filter element such as shown at  396  in  FIG. 34 . The panel filter element includes filter media  398  having a perimeter or border  400  which may include a frame and/or seal for mounting in a housing. A reinforcement band  402  is provided along at least a portion of the perimeter and performs the noted support function thereat upon attempted percussive cleaning of filter element  396  by service personnel striking perimeter  400  against an impact surface such as  304 ,  FIG. 15 . Panel filter element  396  is generally flat and may have various perimeteral border shapes, including rectangular. The noted reinforcement band at  402  may include or be replaced by a failure band  404  along at least a portion of perimeter  400  and performing the noted designated failure function to the noted failure condition thereat upon attempted percussive cleaning of filter element  396  by service personnel striking perimeter  400  against an impact surface, e.g. at  304 , the failure condition providing at least one of: a) an indication to service personnel that the filter element has been damaged and should not be re-installed; and b) a deformed condition preventing re-installation. Indicia may be provided on failure band  404 , for example comparably to indicia band  394 ,  FIG. 33 . 
     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.