Abstract:
One embodiment is a unique replaceable filter element. Further embodiments, forms, objects, features, advantages, aspects, and benefits shall become apparent from the following description and drawings.

Description:
This is a continuation of application Ser. No. 11/888,037 filed Jul., 31 2007 now U.S. Pat. No. 7,882,961 which is a continuation-is-part application of U.S. application Ser. No. 11/264,473 filed Nov. 1, 2005 now abandoned. 
    
    
     BACKGROUND 
     Replaceable filter elements and assemblies including replaceable filter elements have proven to be useful components of filtration systems for applications in internal combustion engines such as diesel engines. Replaceable filter elements can be provided along with other components of filtration systems to provide assemblies operable to filter liquids such as oil and other lubricants, hydraulics, fuels, and others. Present approaches to replaceable filter elements and assemblies suffer from a variety of drawbacks, limitations, disadvantages and problems including those respecting sealing adequacy, part count, complexity, serviceability, cost, durability, thermal matching and others. 
     SUMMARY 
     One embodiment is a unique replaceable filter element. Another embodiment is a unique assembly including a replaceable filter element. Further embodiments, forms, objects, features, advantages, aspects, and benefits shall become apparent from the following description and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  is a perspective view of a replaceable filter element. 
         FIG. 2  is a sectional view of a replaceable filter element. 
         FIG. 3  is a sectional view of a filter assembly. 
         FIG. 4  is a perspective view of a head insert. 
         FIG. 5  is a sectional view of a portion of a filter assembly. 
         FIG. 6  is a sectional view of a portion of a filter assembly. 
         FIG. 7  is a sectional view of a portion of a filter assembly. 
         FIG. 8  is a perspective view of a portion of a filter assembly. 
         FIG. 9  is a sectional view of a portion of a filter assembly. 
         FIG. 10  is a front elevational view of a fluid filter assembly. 
         FIG. 11  is a side sectional view of the  FIG. 10  fluid filter assembly. 
         FIG. 12  is a front sectional view of the  FIG. 10  fluid filter assembly. 
         FIG. 13  is an exploded view of  FIG. 10  fluid. 
         FIG. 14  is a front elevational view of a fluid filter cartridge comprising one portion of  FIG. 10 . 
         FIG. 15  is a front elevational view of a molded plastic housing comprising a portion of  FIG. 10 . 
         FIG. 16A  is a partial, enlarged detail view of one slot style. 
         FIG. 16B  is a partial, enlarged view of another slot style. 
         FIG. 17  is a side elevational view of  FIG. 15 . 
         FIG. 18  is a perspective view of  FIG. 15 . 
         FIG. 19  is a top plan view of a molded plastic endplate comprising a portion of  FIG. 14 . 
         FIG. 20  is a front elevational view of  FIG. 19 . 
         FIG. 21  is a perspective view of  FIG. 19 . 
         FIG. 22  is a perspective view of a removal procedure. 
         FIG. 23  is a partial perspective view of a filter assembly. 
     
    
    
     DETAILED DESCRIPTION 
     For purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated embodiments, and such further applications of the principles of the invention as illustrated therein being contemplated as would occur to one skilled in the art to which the invention relates. 
     With reference to  FIG. 1  there is illustrated a perspective view of a replaceable filter element  100 . While replaceable filter element  100  is an engine lubricant filter in a preferred embodiment, it is also contemplated as being applicable to a filter for a variety of engine and vehicle fluids such as fuels, hydraulics, and others. Replaceable filter element  100  includes filter media  110 , endplate  120  coupled to one end of filter media  110 , and endplate  130  coupled to another end of filter media  110 . In the illustrated embodiment, filter media  110  is in an annular and pleated configuration extending from a first end to a second end and defining an interior cavity. Other embodiments contemplate other filter media configurations including, for example, a stack disc bypass filter media configuration or other filter media configurations. 
     Endplate  120  includes an opening  127  leading to the interior cavity of filter media  110 . Sealing flange  125  is positioned adjacent opening  127  and extends from endplate  120  in a generally axial direction. Flange  128  is positioned radially outward from flange  125  and extends from endplate  120  in a generally axial direction. Endplate  120  extends from opening  127  to outer periphery  126 . Endplate  120  also includes at least a first plurality of legs  121  which extend from periphery  126  and may also include a second plurality of legs  122  which extend from periphery  126  as is shown in the illustrated embodiment. Endplate  120  is preferably a unitary structure formed of a plastic material such as thermoplastic. Other embodiments contemplate that endplate  120  could be formed of multiple pieces coupled together. 
     With reference to  FIG. 2  there is illustrated a sectional view of a replaceable filter element  200 . Replaceable filter element  200  includes filter media  210 , endplate  220  coupled to one end of filter media  210 , and endplate  230  coupled to another end of filter media  210  which are similar to filter media  110 , endplate  120 , and endplate  130  of replaceable filter element  100  described above in connection with  FIG. 1 . Replaceable filter element  200  also includes centerpost  240  which extends from endplate  230  to endplate  220  in the interior cavity of filter media  210 . Other embodiments contemplate replaceable filter elements without a centerpost. In one replaceable filter embodiment without a centerpost, endplate  230  includes an opening permitting a centerpost to be introduced into the interior cavity of filter media  210 . The centerpost which is introduced into the interior cavity can be an independent component, or can be a component of another portion of a filter assembly. 
     With reference to  FIG. 3  there is illustrated a sectional view of a filter assembly  300 . Filter assembly  300  includes a replaceable filter element  309 , shell  350 , filter head  360 , and head insert  400 . Replaceable filter element  309  includes filter media  310 , endplate  320  coupled to one end of filter media  310 , and endplate  330  coupled to another end of filter media  310  which are similar to filter media  110 , endplate  120 , and endplate  130  of replaceable filter element  100  described above in connection with  FIG. 1 . 
     Shell  350  includes a body wall  351  which defines a hollow interior into which replaceable filter element  309  is inserted. Shell  350  is received by receptacle  370  which is a region of filter head  360  configured to receive a portion of shell  350  and a portion of replaceable filter element  309 . Shell  350  further includes recesses  352  which receive legs  322  of endplate  320 , threads  353  which mate with threads  361  of receptacle  370  to form a threaded interconnection  390 , sealing ring  354  which provides a seal between shell  350  and receptacle  370 , and abutment flange  355  which contacts filter head  360 . Shell  350  also includes centerpost  340  which is coupled to the bottom end of shell  350  and is introduced into the interior cavity of replaceable filter element  309  when replaceable filter element  309  is placed into the hollow interior of shell  350 . Shell  350  further includes water drainage valve  356  located at the bottom of shell  350 . 
     Head insert  400  is coupled with filter head  360  and extends into receptacle  370 . Head insert  400  includes a bearing surface which contacts sealing flange  325  of endplate  320  to form a seal. Other embodiments contemplate that head insert  400  could be omitted and sealing flange  325  could contact a portion of filter head  360  to form a seal. In either instance sealing flange  325  can form a seal with the bearing surface that it contacts without requiring any intermediate structure such as a gasket or sealing ring. It is preferred that sealing flange  325  and the surface which it contacts are of the same or similar material, though the materials of the two components may differ in other embodiments. 
     With reference to  FIG. 4  there is illustrated a perspective view of a head insert  400 . Head insert  400  includes detent clips  410  which can couple head insert  400  to a filter head, for example, as illustrated in  FIG. 3 . Other embodiments contemplate that head insert  400  and the other filter heads described herein could include other means for coupling to a filter head, such as, threads, other clips, screws, and other fasteners, for example. Head insert  400  also includes o-ring  420  which forms a seal between head insert  400  and the filter head. Head insert  400  further includes recesses  430  formed in lower rim  429  which can provide computability detection for replaceable filter elements and rejection of incompatible filter elements. Embodiments which utilize recesses  430  contemplate that replaceable filter elements with sealing flanges or other structures configured to mate with recesses  430 , for example by including protrusions which mate with recesses  430 , will be used in a filter assembly. Head insert  400  will not couple with incompatible filter elements which lack compatible mating structures. Head insert  400  can provide protection against inadvertent installation of replaceable filter elements which are not suited for a particular application. 
     With reference to  FIG. 5  there is illustrated a sectional view of a portion of a filter assembly  500 . The illustrated portion of filter assembly  500  includes replaceable filter element  509 , shell  550 , head insert  599  which is coupled to a filter head (not illustrated), and centerpost  540  which has been positioned in the interior cavity of replaceable filter element  509 . Replaceable filter element  509  includes filter media  510  and endplate  520  coupled to one end of filter media  510 . 
     Endplate  520  is preferably a unitary structure formed of a plastic material such as thermoplastic. Other embodiments contemplate that endplate  520  could be formed of multiple pieces coupled together. Endplate  520  includes a sealing flange  525  which extends from endplate  520  in a generally axial direction. Flange  528  is positioned radially outward from flange  525  and extends from endplate  520  in a generally axial direction. Endplate  520  extends from a central opening to outer periphery  526 . Endplate  520  also includes leg  521  which extends from periphery  526  and leg  522  which extend from periphery  526 . Leg  521  includes a first portion  5211  which extends from periphery  526  in an axial direction away from filter media  510  to a bend  5212 , and a second portion  5213  which extends from bend  5212  in a radially outward direction to leg extremity  5214 . Leg  522  includes a first portion  5221  which extends from periphery  526  in an axial direction toward filter media  510  to a bend  5222 , and a second portion  5223  which extends from bend  5222  in a radially outward direction to leg extremity  5224 . Endplate  520  further includes additional legs similar to legs  521  and  522  extending from other locations about periphery  526 . A number of additional embodiments contemplate different shapes, sizes, numbers, and configurations for legs  521  and  522 . For example, legs  521  and/or legs  522  could extend from periphery  526  at angles directed inward or outward relative to the angle of the illustrated embodiment. In another example, legs  521  and/or legs  522  extend from their respective bends in directions more upward or more downward relative to the direction of the illustrated embodiment. In a further example, the angle formed by the portions extending to and from the bends could be greater or lesser than that of the illustrated embodiment. In an additional example, one or more portions of legs  521  and/or legs  522  could have greater or lesser lengths, widths, thicknesses or other dimensions than those of the illustrated embodiment. In a further example, the curvature of one or more bends could be greater or lesser than the illustrated embodiment. In another example, legs  521  and/or  522  might omit bends and could extend directly to their respective extremities. In additional embodiments, the number and/or directional projection of legs may vary in further manners, for example, as illustrated elsewhere herein. 
     When replaceable filter element  509  is inserted into shell  550 , leg  522  is received in a recess formed in shell  550 . When shell  550  is coupled to a filter head contact between leg  522  and shell  550  provides a sealing force to endplate  520  including to sealing flange  525  in a direction axially toward head insert  599 . Additionally, when shell  550  is coupled to a filter head contact between leg  521  and the filter head provides a force to endplate  520  in a direction axially toward shell  550 . Head insert  599  includes detent clips  591  which couple head insert  599  to the filter head and o-ring  592  which forms a seal between head insert  599  and the filter head. Head insert  599  also includes flange  598  which includes surface  597 . When replaceable filter element  509  is inserted into shell  550  and shell  550  is coupled to the filter head, surface  597  of flange  598  contacts sealing flange  525  to form a seal. The force between surface  597  of flange  598  and sealing flange  525  causes sealing flange  525  to deform, for example, to the illustrated position. Surface  597  is at a shallow angle which tends to cause sealing flange  525  to deform to the illustrated configuration. Other embodiments contemplate surfaces having different angles resulting in different sealing flange deformation, for example, inward, or outward to a greater or lesser degree. The force of sealing flange  525  against surface  597  is sufficient to maintain the seal between sealing flange  525  and surface  597 , and intermediate structure such as a gasket or sealing ring is not necessary. 
     With reference to  FIG. 6 , there is illustrated a sectional view of a portion of a filter assembly  600 . The illustrated portion of filter assembly  600  includes replaceable filter element  609  which is inserted into a shell (not illustrated) in the same or a similar manner as described above, head insert  699  which is coupled to a filter head (not illustrated), and centerpost  640  which has been positioned in the interior cavity of replaceable filter element  609 . The illustrated portion of replaceable filter element  609  includes filter media  610  and endplate  620  coupled to one end of filter media  610 . 
     Endplate  620  is preferably a unitary structure formed of a plastic material such as thermoplastic. Other embodiments contemplate that endplate  620  could be formed of multiple pieces which could be coupled together. Endplate  620  includes a sealing flange  625  which extends from endplate  620  in a generally axial direction. Flange  628  is positioned radially outward from flange  625  and extends from endplate  620  in a generally axial direction. Endplate  620  extends from a central opening to outer periphery. Endplate  620  also includes legs (not illustrated) which extends from its outer periphery in the same or a similar manner as legs  521  and  522  described above in connection with  FIG. 5 . 
     When replaceable filter element  609  is inserted into the shell, contact between legs of replaceable filter element  609  and the shell provides a sealing force to endplate  620  including to sealing flange  625  in a direction axially toward head insert  699  in the same or a similar manner as was described above in connection with  FIG. 5 . Additionally, when the shell is coupled to the filter head, contact between other legs and the filter head provides a force to endplate  620  in a direction axially toward the shell. Head insert  699  includes detent clips  691  which couple head insert  699  to the filter head and o-ring  692  which forms a seal between head insert  699  and the filter head. Head insert  699  also includes member  698  which includes surface  697 . When replaceable filter element  609  is inserted into the shell and the shell is coupled to the filter head, surface  697  contacts sealing flange  625  to form a seal. The force between surface  697  and sealing flange  625  causes sealing flange  625  to deform, for example, to the illustrated position. Surface  697  is at a steeper angle than surface  597  of  FIG. 5  which tends to cause sealing flange  625  to deform to the illustrated configuration. The force of sealing flange  625  against surface  697  is sufficient to maintain the seal between sealing flange  625  and surface  697 , and intermediate structure such as a gasket or sealing ring is not necessary. 
     With reference to  FIG. 7  there is illustrated a sectional view of a portion of a filter assembly  700 . The illustrated portion of filter assembly  700  includes replaceable filter element  709  which is inserted into a shell (not illustrated) in the same or a similar manner as described above, head insert  799  which is coupled to a filter head (not illustrated), and centerpost  740  which has been positioned in the interior cavity of replaceable filter element  709 . The illustrated portion of replaceable filter element  709  includes filter media  710  and endplate  720  coupled to one end of filter media  710 . 
     Endplate  720  is preferably a unitary structure formed of a plastic material such as thermoplastic. Other embodiments contemplate that endplate  720  could be formed of multiple pieces coupled together. Endplate  720  includes a sealing flange  725  which extends from endplate  720  in a generally axial direction. Flange  728  is positioned radially outward from flange  725  and extends from endplate  720  in a generally axial direction. Endplate  720  extends from a central opening to outer periphery. Endplate  720  also includes legs (not illustrated) which extend from its outer periphery in the same or a similar manner as legs  521  and  522  described above in connection with  FIG. 5 . 
     When replaceable filter element  709  is inserted into the shell, contact between legs of replaceable filter element  709  and the shell provides a sealing force to endplate  720  including to sealing flange  725  in a direction axially toward head insert  799  in the same or a similar manner as was described above in connection with  FIG. 5 . Additionally, when the shell is coupled to the filter head, contact between other legs and the filter head provides a force to endplate  720  in a direction axially toward the shell. Head insert  799  includes detent clips  791  which couple head insert  799  to the filter head and o-ring  792  which forms a seal between head insert  799  and the filter head. Head insert  799  also includes member  798  which includes surface  797 . When replaceable filter element  709  is inserted into the shell and the shell is coupled to the filter head, surface  797  contacts sealing flange  725  to form a seal. The force between surface  797  and sealing flange  725  causes sealing flange  725  to deform, for example, to the illustrated position. Surface  797  is at a generally vertical angle relative to sealing flange  725  which tends to cause sealing flange  725  to deform to the illustrated configuration. The force of sealing flange  725  against surface  797  is sufficient to maintain the seal between sealing flange  725  and surface  797 , and intermediate structure such as a gasket or sealing ring is not necessary. 
     With reference to  FIG. 8  there is illustrated a perspective view of a portion of a filter assembly  800 . Filter assembly  800  includes a replaceable filter element  810  and a shell  850  which are configured to couple to a filter head which may include a head insert. Replaceable filter element  810  includes filter media, endplate  820  coupled to one end of the filter media, and may also include another endplate coupled to another end of filter media. Replaceable filter element  810  is a stack-disc bypass filter element which includes a plurality of stacked discs of filter media. Replaceable filter element  810  also includes vertically extending supports  840  which extend along the axial length of replaceable filter element  810 . 
     Endplate  820  includes an opening  827  leading to the filter media of replaceable filter element  810 . Sealing flange  825  is positioned adjacent opening  827  and extends from endplate  820  in a generally axial direction. Endplate  820  extends from opening  827  to outer periphery  826 . Endplate  820  also includes at least a first plurality of legs  821  which extend from periphery  826  and may also include a second plurality of legs  822  which extend from periphery  826  as shown in the illustrated embodiment. Legs  821  and  822  extend from periphery  826  in the same or a similar manner as legs  521  and  522  described above in connection with  FIG. 5 . Endplate  820  is preferably a unitary structure formed of a plastic material such as thermoplastic. Other embodiments contemplate that endplate  820  could be formed of multiple pieces. 
     Shell  850  includes a body wall which defines a hollow interior into which replaceable filter element  810  is inserted. Shell  850  includes recesses  852  which receive legs  822  of endplate  820 , threads  853  which mate, sealing ring  854 , and abutment flange  855 . Shell  850  may further include a water drainage valve (not illustrated) located at the bottom of shell  850 . 
     With reference to  FIG. 9  there is illustrated a sectional view of a portion of a filter assembly  900 . Filter assembly  900  includes a replaceable filter element  909 , shell  950 , filter head  990 , and head insert  1000 . Replaceable filter element  909  includes filter media  910 , endplate  920  coupled to one end of filter media  910 , and may include another endplate coupled to another end of filter media  910 . Replaceable filter element  909  is a stack-disc bypass filter element which includes a plurality of stacked discs of filter media  910 . Hollow interior portions are located between successive discs of filter media  910 . Replaceable filter element  910  also includes vertically extending supports which extend along the axial length of replaceable filter element  909  in the same or a similar manner as vertically extending supports  840  described above in connection with  FIG. 8 . 
     Shell  950  includes a body wall  951  which defines a hollow interior into which replaceable filter element  909  is inserted. Shell  950  is received in receptacle  970  which is a region of filter head  960  configured to receive a portion of shell  950  and a portion of replaceable filter element  909 . Shell  950  further includes recesses  952  which receive legs  922  of endplate  920 , threads  953  which mate with threads of receptacle  970  to form a threaded interconnection  990 , sealing ring  954  which provides a seal between shell  950  and receptacle  970 , and abutment flange  955  is which contact filter head  960 . Shell  950  may further include a water drainage valve located at the bottom of shell  950 . 
     Head insert  1000  is coupled with filter head  960  and partially extends into receptacle  970 . Head insert  1000  includes a bearing surface which contacts sealing flange  925  of endplate  920  to form a seal. Other embodiments contemplate that head insert  1000  could be omitted and sealing flange  95  could contact a portion of filter head  960  to form a seal. In either instance sealing flange  925  can form a seal with the bearing surface that it contacts without requiring any intermediate structure such as a gasket or sealing ring. It is preferred that sealing flange  925  and the surface which it contacts are of the same or similar material though the materials of the two components may differ in other embodiments. 
     With reference to  FIGS. 10-14 , there is illustrated a fluid filter assembly  20  that is constructed and arranged for threaded connection to a fluid-delivery mounting head (not illustrated). Fluid filter assembly  20  includes a unitary, molded plastic shell  21  and a cooperating fluid filter cartridge  22 . The fluid filter cartridge  22  (see  FIG. 5 ) includes a generally cylindrical filtering media element or filter media pack  23  and a unitary, molded plastic endplate  24  that is securely attached, such as by adhesive bonding, to the upper end of the filter media pack  23 . In further embodiments, the fluid filter cartridge could conform to the other embodiments described herein. 
     With reference to  FIGS. 15-18 , a shell  21  is illustrated. The generally cylindrical body  27  includes an annular sidewall  28  that defines open end  29 . Shell  21  also is includes a closed base  30  that is integral with cylindrical body  27 . While the base  30  is described as “closed”, there are two defined apertures  31  and  32  (see  FIG. 12 ). These two defined apertures provide the capability of water sensing ( 31 ) and water drainage ( 32 ) for the fluid filter assembly  20 . The additional socket  35  is for a one-way removal feature. The inner surface  33  of sidewall  28  includes a uniformly spaced-apart series of structural ribs  34 . Ribs  34  are unitarily molded as part of shell  21  and provide structural support and rigidity to the shell as well as a deterrent against the attempted use of any non-standard filter media, such as a spin-on filter style intended for single-use as part of a disposable fluid filter assembly. One feature of note, though not illustrated, is the elimination from these inner ribs  34  of any type of rib ledge or shelf that would typically be used to support the filtering element (spin-on, single-use style) as depicted in certain prior constructions. Eliminating a rib ledge or shelf and extending ribs  34  axially provides the mentioned structural support to shell  21  and eliminates any support structure that might otherwise control the axial depth of an installed fluid filter cartridge. This structural design change to shell  21  in turn requires some utilization of the open end  29  in order to control the insertion depth of any fluid filter or filter media pack into shell  21 . 
     The outer surface  37  of sidewall  28  adjacent upper edge  38  of open end  29  is constructed and arranged with a series of molded threads  39  that are used to securely attach fluid filter assembly  20 , for example, to a fluid-routing head (not illustrated). Further, the sidewall  28 , in cooperation with the closed base  30 , defines a generally cylindrical interior space for shell  21  that is constructed and arranged to receive the fluid filter cartridge  22 . Upper edge  38  that helps to define open end  29  is considered to be an exposed or free edge and open end  29  constitutes the entrance opening of the shell, noting that the opposite end of the shell includes closed base  30 . As noted, the fluid filter cartridge  22  is installed into the shell by inserting the fluid filter cartridge into the interior space by way of this entrance opening. 
     Shell  21  is preferably a molded plastic shell that is used without a nutplate though additional embodiments contemplate use of a nutplate. The enlarged series of outer threads  39 , in terms of the outside diameter size of shell  21 , requires a compatible head design so as to change from the head structure that would be used for head connection to a nutplate. Shell  21  is constructed and arranged so as to reject or prevent the insertion of a spin-on style of fluid filter. Both single use and multi-use embodiments are contemplated. Wall thickness can be somewhat less for a single use filter assembly as compared to the desire for a slightly thicker wall when the shell is designed for multiple uses., i.e., reuse with replaceable fluid filter cartridges, as presented for the disclosed invention. If the same basic shell shape is going to be used for both types of fluid filter assemblies, disposable as well as multiple use, various design changes will be made. 
     For some of the shell design differences, the spin-on, disposable style does not require any notches or slots, as shown in  FIGS. 15 ,  16 A and  16 B, while the replaceable, cartridge style preferably includes such notches. For the spin-on, disposable style, radial ledges are preferably used as part of the structural ribs on the interior of the shell to position the fluid filter element and to set its axial height down into the interior of the shell. The replaceable cartridge style does not require radial ledges since its axial depth and positioning are controlled by the endplate configuration and its interfit into the spaced series of six notches or slots  42  and  43 . When the rib ledges are molded as a part of the unitary plastic shell, the interior space of the shell can be described as having an interior abutment ledge. This surface that supports or otherwise positions the lower portion of the installed fluid filter element to maintain the proper axial depth of that element into the shell. 
     If a spin-on, disposable style of fluid filter assembly is selected, the core diameter for the shell molding process can be increased in size, resulting in a thinner wall as compared to the increased wall thickness desired for the replaceable, fluid filter cartridge style. This difference in wall thickness assumes that the overall outer size and shape of the shell is basically the same for both of these fluid filter assembly styles. When the fluid filter assembly is designed as a single-use, disposable assembly, the shell wall thickness does not have to be as great as when the shell is used and re-used multiple times. Varying the shell wall thickness can be achieved by varying the inserted core diameter during the molding process. 
     In order for shell  21  to be configured for use with a replaceable cartridge style of fluid filter element, the upper exposed edge  38  can be configured with a series of six (6) recessed notches or slots (see  FIGS. 15 ,  16 A and  16 B). In the preferred embodiment that is illustrated, there are two slots  42  that are constructed and arranged with a first shape and four slots  43  that are constructed and arranged with a second shape that is slightly different from the first shape. In one arrangement of the disclosed fluid filter assembly, these six slots  42  and  43  are equally spaced around upper edge  38 . For this one arrangement of six (6) slots, the replaceable fluid filter cartridge  22  can be installed in any one of six orientations in terms of its rotation relative to the shell, as will be described herein as part of the description of the fluid filter cartridge  22  and endplate  24 . In a second arrangement, the spacing between the series of six (6) slots  42  and  43  is not equal, but random or varied, such that there is only a single orientation for the fluid filter cartridge to insert into the shell  21 . A varied spacing for the six slots requires a corresponding varied spacing for the projections  46  of the endplate  24 , as described herein. 
     Referring to  FIGS. 19-21 , endplate  24  is illustrated. The filtering media pack  23  is a generally cylindrical, pleated, filtering media structure or element and the plastic endplate  24  is adhesively bonded to the upper exposed end of the filter media pack  23  in order to create fluid filter cartridge  22 . Endplate  24  is a unitary, molded plastic component that includes an open cylindrical sleeve  44  for receipt by the head for routing of the exiting fluid after it passes through the filtering media pack  23 . An annular face seal (sealing) gasket  45  is positioned around sleeve  44  (see  FIGS. 11 and 12 ) for a liquid-tight sealed interface between the endplate  24  and the head. As the shell threads onto the head, the gasket  45  engages a surface of the head causing gasket compression with continued threaded engagement. 
     Seating of the fluid filter cartridge  22  into shell  21  is achieved by the use of slots  42  and  43  and cooperating outwardly-extending radial projections  46 . There are six projections  46  that are constructed and arranged to match the spacing of the slots  42  and  43 . Each projection  46  has an L-shaped form with an upper, outwardly extending section  46   a , an axially depending section  46   b , and a lower, outwardly extending radial lip  46   c . While there are two styles of slots  42  and  43  as described and as will be explained in greater detail, all six projections  46  are constructed and arranged with the same size and shape. Each projection  46  includes concave side surfaces  46   d  and  46   e  (see  FIG. 19 ), creating the appearance of an outwardly tapering shape for each projection  46 . Radial lip  46   c  is constructed and arranged with a generally horizontal, substantially flat lower surface  46   f.    
     As is illustrated and as would be understood from the foregoing descriptions, upper edge  38  of sidewall  28  defines open end  29 . The inside diameter surface of upper edge  38  (or sidewall  28  at its upper end) coincides with the outside diameter of the open area of the generally circular open end  29 . So that fluid filter cartridge  22  uses upper edge  38  for the positioning of cartridge  22  within shell  21 , the outside diameter dimension of the endplate  24 , as measured over or across the outer tips of the projections  46 , preferably exceeds the outside diameter of the open area of open end  29 . The outside diameter across the outer tips of projections  46  preferably does not extend beyond the outside diameter of shell  21 , at least not to any noticeable degree or extent that would potentially interfere with the threaded connection of the shell  21  to the head. 
     In terms of the number of slots and the number of projections, it will be noted that the proper assembly of the fluid filter cartridge  22  into shell  21  requires a receiving slot, either  42  or  43 , for each projection  46 . If there are any slots in upper edge  38  that do not receive a projection  46 , then there is a gap left at that location on edge  38 . If there is an “extra projection  46  that does not have a corresponding receiving slot, properly sized and positioned, it will cause interference with the upper edge  38  of shell  21  at the time of attempted installation of the cartridge  22  into the shell  21 . This interference of a projection  46  resting on top of edge  38  prevents proper seating of the fluid filter assembly against the head. The assembly and proper seating of fluid filter cartridge  22  into shell  21  is illustrated in  FIGS. 11 and 12 . This proper seating positions each projection  46  down into a corresponding one of the receiving slots  42 ,  43 . The two slots  42  are constructed and arranged for a secure capture of the inserted projection  46 , for example, by an interference fit. The other four slots  43  are each constructed and arranged for a close clearance receiving fit of their corresponding projection  46 . These other four slots  43  provide support for the fluid filter cartridge  22 . All six slots  42 ,  43  cooperate with their receiving projections  46  in order to set the desired insertion depth of the fluid filter cartridge  22  into shell  21 . The interfit between the projections  46  and slots  42 ,  43  also prevents any rotation of the fluid filter cartridge  22  relative to shell  21 , once the fluid filter cartridge is properly installed. It will also be noted from the various figures that each projection  46 , specifically the radial lip  46   c , is recessed below the upper surface of exposed upper edge  38 . The number of slots  42  and the complementing number of slots  43  can be varied from 6-0 to 0-6 and all combinations between these extremes. If added security is desired in terms of physically capturing one or more of the projections  46 , then the side walls of the receiving slot can be shaped with detent ribs or bumps for a snap fit. 
     Slot  42  is illustrated in greater detail in  FIG. 16A  and slot  43  is illustrated in greater detail in  FIG. 16B . The broken line outline in each of these two drawing figures represents the shape and proper positions of section  46   c  of the received projection  46 . The construction and arrangement of each slot  42  creates a sufficiently tight interference fit with the received projection  46  to anchor and hold the fluid filter cartridge  22  into shell  21 . As illustrated, a small clearance space  49  is defined beneath section  46   c  and is located between lower surface  50  of slot  42  and the flat lower surface  46   f  of the corresponding projection  46 . The clearance space  49  is used to receive the flat tip of hand tool, such as a screwdriver, in order to be able to pry up on the corresponding projection  46  that is received within slot  42  in order to pop the projection free of its interference fit (see  FIG. 22 ). As noted, it is not possible to install the fluid filter cartridge  22  unless the correct shell  21  has been selected. 
     Due to the outwardly extending design of projections  46  in a radially outward direction from the outer circular edge  51  of endplate  24 , flow clearance spaces  52  are defined between each pair of adjacent projections  46 . See  FIG. 23  for one example of a defined flow clearance space  52 . These clearance spaces provide is the necessary flow channels into shell  21  for the fluid to be filtered by the filtering media element. The outline of each clearance space  42  is defined by the inner surface of upper edge  38 , the outer circular edge  51 , and the adjacent pair of projections  46 . These six clearance spaces  52  provide a flow path for the fluid to be filtered that arrives by way of the head and flows onto the endplate outside of the return flow sleeve  44 . This allows faster and smoother routing of the fluid flow in view of the number and size of the flow openings (i.e., clearance spaces  52 ) and enables more efficient fluid filtration and processing. As the fluid to be filtered flows across the exposed surface of the endplate, it reaches the flow clearance spaces  52  and flows through these spaces to the annular clearance space defined by and between the inside surface  33  of the sidewall  28  and the outer cylindrical surface (pleated) of the filter media pack  23 . 
     The cartridge endplate  24  and cooperating shell  21  preferably reduce or eliminate the possibility that an incorrect or improper fluid filter cartridge will be installed. Any cartridge without the proper number, style, and spacing of endplate projections  46  will not fit “properly” into the shell  21 . The elimination of the rib ledge structures from the axially extending ribs  34  means that there is nothing to support the non-approved fluid filter cartridge when inserted into the shell and there is nothing to set or control the desired depth for the cartridge except for the upper edge  38  of sidewall  28  of shell  21 . If the upper edge is attempted to be used in some manner to control the depth of the cartridge, it means that the edge cannot fit flush against or within the head. This also prevents proper compression of the gasket or seal and will result in leakage. The only option for a proper assembly and proper fit to the head is to utilize slots  42  and  43  with the designed number of cooperating projections as part of the endplate. However, that cooperating structure would mean an endplate conforming to the configuration of endplate  24  and thus the only fluid filter cartridge fully compatible with shell  21  is to use one that is designed to cooperate with slots  42  and  43 . The retention capability afforded by the interference fit and insertion of projections  46  into slots  42  and  43  means that there will be an important retention feature during the assembly process. 
     The cartridge  22  and shell  21  combination also permits an increased media area. By using the endplate  24  and the upper edge  38  to set the axial depth of cartridge  22 , the media portion of the cartridge can be longer. This embodiment raises the upper edge of the cartridge closer to edge  38  and the opposite end can be extended deeper into the shell. 
     While exemplary embodiments of the invention have been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiments have been shown and described and that all to changes and modifications that come within the spirit of the invention are desired to be protected. It should be understood that while the use of words such as preferable, preferably, preferred or more preferred utilized in the description above indicate that the feature so described may be more desirable, it nonetheless may not be necessary and embodiments lacking the same may be contemplated as is within the scope of the invention, the scope being defined by the claims that follow. In reading the claims, it is intended that when words such as “a,” “an,” “at least one,” or “at least one portion” are used there is no intention to limit the claim to only one item unless specifically stated to the contrary in the claim. When the language “at least a portion” and/or “a portion” is used the item can include a portion and/or the entire item unless specifically stated to the contrary.