Abstract:
The structural integrity of opposed spaced-apart end plates of caged filter cartridge assemblies is provided solely by individual filter cartridges in the assembly. Preferably, the end plates of the filter cartridge assembly are provided with seat recesses to receive an end portion of respective filter cartridges therein. An annular lock ring associated with each seat recess immovably locks the filter cartridge end portions therewithin. In such a manner, each of the individual filter cartridges serves to structurally unite the opposed spaced-apart end plates one to another in the absence of a tie rod so that the collective torsional and longitudinal rigidity of the assembly is significantly enhanced as compared to conventional tie rod caged filter cartridge assemblies.

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to the field of filtration assemblies. In its more preferred forms, the present invention relates to multiple tubular filter cartridges which are held together as a unit (“caged”) in parallel relationship to one another between spaced-apart end plates, and to the filtration systems which employ the same. 
     BACKGROUND AND SUMMARY OF THE INVENTION 
     Caged filter cartridge assemblies are known and have been employed conventionally in fluid-filtration assemblies. Conventional caged filter assemblies typically include an array comprised of a large number (e.g., eighteen) of generally tubular filter cartridges positioned parallel to one another between a pair of spaced-apart end plates. A tie rod extends generally centrally of the filter cartridge array and structurally unites the spaced-apart end plates to form an integral unit. 
     The integrity of the structural union between the end plates and the filter cartridges provided by the tie rod associated with conventional caged filter assemblies is problematic. Specifically, the tie rod does not impart sufficient torsional rigidity to the conventional caged filter cartridge assemblies. As a result, during shipment and/or handling, the filter cartridges may twist about the axis of the tie rod resulting in some of the seals being broken or damaged between individual ones of the filter cartridges and the end plates. Broken or damaged seals, of course, results in reduced filtration efficiencies during use. 
     An additional problem associated with conventional caged filter cartridges is potential “dishing” that may be imparted to the end plates by virtue of the tie rod being over-torqued during assembly. That is, there exists a real possibility that the axial compressive force on the end plates provided by the tie rod may be somewhat greater in the immediate vicinity of the tie rod and somewhat lesser at the peripheral annular edge regions of the plates. As a result, the area in the immediate vicinity of the centrally located tie rod may be recessed somewhat as compared to the peripheral annular edges of the plate, thereby resulting in a “dished” appearance. Such “dishing” of the end plates can also lead to broken seals between individual ones of the filter cartridges and the end plates leading to ineffective filtration capabilities during use. 
     It would therefore be highly desirable if improved caged filter cartridge assemblies could be provided which exhibits increased torsional rigidity without “dishing” the end plates and thereby maintain reliable seals between the individual filter cartridges and such end plates. It is toward providing such improved caged filter cartridge assemblies that the present invention is directed. 
     Broadly, the present invention is embodied in tie rod-less caged filter cartridge assemblies wherein the structural integrity of the assembly is provided solely by means of the individual filter cartridges. More specifically, according to the present invention, the end plates of the filter cartridge assembly are provided with plural seat recesses each adapted to receive an end portion of a respective filter cartridge. An annular lock ring is associated with each seat recess so as to immovably lock the filter cartridge ends therewithin. In such a manner, each of the individual filter cartridges serves to structurally unite the opposed spaced-apart end plates one to another in the absence of a tie rod so that the collective torsional and longitudinal rigidity of the assembly is significantly enhanced as compared to conventional tie rod assemblies. 
     These and other aspects and advantages will become more apparent after careful consideration is given to the following detailed description of the preferred exemplary embodiments thereof. 
    
    
     BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS 
     Reference will hereinafter be made to the accompanying drawings, wherein like reference numerals throughout the various FIGURES denote like structural elements, and wherein; 
     FIG. 1 is an elevational perspective view of a filtration system, partly in section, which employs a caged filter cartridge assembly in accordance with the present invention; 
     FIG. 2 is an enlarged elevational perspective view of an exemplary caged filter cartridge assembly in accordance with the present invention; 
     FIG. 3 is an enlarged perspective view of an exemplary end plate employed in the caged filter cartridge assembly in accordance with the present invention; 
     FIG. 4 is an enlarged cross-sectional perspective view of the exemplary end plate depicted in FIG.  3  and taken along line  4 — 4  therein; 
     FIG. 5 is an enlarged cross-sectional elevational view of an exemplary recessed filter cartridge seat provided in the end plates of the present invention; and 
     FIGS. 6A and 6B respective depict the coupling post before and after heat-staking so as to rigidly unite the base and seat plate components of the end plates in accordance with the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Accompanying FIG. 1 depicts a filtration system  1  which includes a caged filter cartridge assembly  10  in accordance with the present invention. As shown, the filtration system  1  generally includes a cylindrical housing  1 - 1  having fluid inlets and outlets,  1 - 2 ,  1 - 3 , respectively, so as to allow fluid to be filtered to enter the interior cylindrical chamber  1 - 4  of the housing  1 - 1 . The fluid within the housing  1 - 1  is thus passed through the filtration medium of the individual filter cartridges  12  positioned between opposed spaced-apart upper and lower end plates  14 ,  16  (see also FIG. 2) and then discharged therefrom through the fluid outlet  1 - 3 . A generally U-shaped gasket seal is typically provided around the perimetrical edge of the end plate  16  so as to provide a fluid seal between it and the interior wall of the housing  1 - 1 . The cylindrical housing  1 - 1  is closed at its upper end by cover  1 - 5  which is securely yet removably coupled to the housing  1 - 1  by means of conventional swing bolt and eye nut assemblies  1 - 6 . When the cover  1 - 5  is opened, therefore, the entire caged filter cartridge assembly  10  may be removed from the interior chamber  1 - 4 , assisted as may be necessary by means of powered lift devices attached to the lift ring  18  of the top plate  14 . Virtually any cylindrical filter cartridge  12  may be employed in the practice of the present invention. The preferred filter cartridges  12  employed in the present invention are generally tubular elongate structures having a central cylindrical interior fluid passageway and filtration media cylindrically positioned around the central passageway. The filtration media is most preferably a non-woven mass of melt-blown polymeric fibers formed, for example, from thermoplastic polymers, preferably polyolefins such as polypropylene, polyethylene and the like. Especially preferred filter cartridges  12  are those as described more fully in commonly owned U.S. Pat. Nos. 5,591,335 and 6,342,283, the entire content of each being expressly incorporated hereinto by reference. 
     As is perhaps more clearly shown in accompanying FIGS. 2, the end plates  14 ,  16  of the caged filter cartridge assembly  10  are comprised of generally circular base and seat plates  14 - 1 ,  16 - 1  and  14 - 2 ,  16 - 2 , respectively. The structural and functional attributes of such circular base and seat plates  14 - 1 ,  16 - 1  and  14 - 2 ,  16 - 2 , respectively, are shown in greater clarity in accompanying FIGS. 3-5 and  6 A- 6 B. In this regard, accompanying FIGS. 3-5 and  6 A- 6 B depict only the end plate  16  as an example of both the end plates  14 ,  16 . It should, however, be understood that, with the exception of the lift hook  18 , all structures associated with end plate  16  are likewise embodied in the end plate  14 . Thus, the discussion below with respect to end plate  16  applies equally to the end plate  14 , even though reference numerals corresponding to the identical structures embodied in end plate  14  do not appear in the accompanying drawing FIGS. 3-5 and  6 A- 6 B. 
     As can be seen, the end plate  16  includes a number of seat recesses, an exemplary few of which are identified in the drawings as reference numeral  16 - 3 . As is perhaps more clearly shown in accompanying FIG. 5, each of the seat recesses  16 - 3  includes a cylindrical support tube  16 - 4  projecting outwardly from, and being a unitary part of, the base plate  16 - 1 . The support tube  16 - 4  is sized so as to be received within the central cylindrical passageway associated with each filter cartridge  12  and thereby direct the filtered fluid into the discharge plenum  1 - 7  of the filtration system  1  and on to the discharge opening  1 - 3  in fluid-communication therewith (see FIG.  1 ). A circular rigid end seal  16 - 5  is provided as a one-piece structure with the base plate  16 - 1  and coaxially surrounds the support tube  16 - 4 . As can be seen in FIG. 5, the end seal  16 - 5  is generally triangularly shaped so that its sharp apex is forcibly embedded within the mass of non-woven fibers constituting the filter media of the filter cartridges  12 . As such, the end seal  16 - 5  provides a seal at the end surface of the filter cartridge  12  when seated within the seat recess  16 - 3 . 
     A retaining ring  16 - 6  is provided unitarily as a part of the seat plate  16 - 2  in coaxially laterally surrounding relationship to both the support tube  16 - 4  and the end seal  16 - 5 . The retaining ring  16 - 6  most preferably defines the generatrices of a conical surface and thus establishes an annular edge  16 - 7  which diametrically constricts the upper region of the recessed seat  16 - 3 . The conical segment shape of the retaining ring  16 - 6  and its annular edge  16 - 7  cooperate to ensure that the former is flexed outwardly by insertion of a filter cartridge into the seat recess  16 - 3  to thereby bias the annular edge  16 - 7  thereof forcibly into a circumferential region of the mass of non-woven fibers constituting the filtration media of the filter cartridge  12 . As such, the retaining rings  16 - 6  and their annular edges  16 - 7  establish annular circumferential seals with the filter cartridges  12  when respectively forcibly seated within the seat recesses  16 - 3 . 
     An annular support wall  16 - 8  is formed as a unitary structure with the seat plate  16 - 2  at one end thereof in close annular adjacent proximity to the seat ring  16 - 6 . The opposite end of the support wall  16 - 8  extends to, and is in contact with, the base plate  16 - 1 . The support wall  16 - 8  thereby provides annular structural rigidity around the retaining ring  16 - 6  as well as establishing and maintaining a spaced-apart relationship between the retaining ring  16 - 6  and the base plate  16 - 1 . 
     The base and seat plates  16 - 1  and  16 - 2  are rigidly united to one another by means of connection posts and wells  16 - 10  and  16 - 12 , respectively, as is more clearly depicted in accompanying FIGS. 6A and 6B. In this regard, FIG. 6A depicts a state of assembly of the base and seat plates  16 - 1  and  16 - 2  whereby such plates are registered with one another so that the connection post  16 - 10  projects upwardly from the platform  16 - 14  formed unitarily as part of the base plate  16 - 1  and through the aperture  16 - 10   a  formed in the bottom of the connection well  16 - 10 . Following the registration of the base and seat plates  16 - 1 ,  16 - 2  and the connection posts and wells  16 - 10  and  16 - 12  formed unitarily therewith, respectively, the connection posts  16 - 10  are subject to elevated temperatures so as to melt its top region to form a larger diameter head  16 - 10 ′ as shown in FIG.  6 B. In such a manner, the base and seat plates  16 - 1 ,  16 - 2 , respectively, are joined to one another by virtue of heat-staking of the connection post  16 - 10 . 
     The base and seat plates  16 - 1  and  16 - 2  can, however, be joined to one another by virtually any suitable alternative means. For example, the plates  16 - 1 ,  16 - 2  may be glued or otherwise adhesively joined to one another. Alternatively (or additionally), mechanical means such as nut and bolt assemblies, screws (particularly those of the self-tapping variety), and the like may be employed. 
     In use, caged filter cartridge assembly  10  is fabricated by forcibly inserting respective opposed ends of the individual filter cartridges  12  into the seat recesses formed in each of the end plates  14 ,  16 . As noted previously, inserting the ends of the filter cartridges  12  into the seat recesses will immovably lock the filter cartridges  12  relative to the end plates  16 . In addition, both end and circumferential fluid seals will be established. The individual filter cartridges  12  will thus collectively serve to unite structurally the opposed end plates  14 ,  16  (i.e., in the absence of separate tie rods extending between the end plates  14 ,  16 ). As a result, the torsional and longitudinal rigidity of the assembly  10  is substantially improved as compared to conventional tie rod assemblies. 
     While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.