Abstract:
A filter cartridge comprises a length-adjustable end cap attached to an end of a filter body. The end cap includes an annular seal, a spacer coaxially positioned in spaced relationship with the seal, and a connection member including a cylindrical neck in moveable sealing contact within the seal and in a snug sliding fit within the spacer and an imperforate flange including a seal on a radial outer region thereof. A method of joining an end cap to an end of a generally cylindrical filtration medium comprises positioning an annular spacer ring in a recess of a connection flange of an end cap; melting an exposed portion of the connection flange; contacting the melted exposed portion of the flange and an end of a filter body; and allowing the melted exposed portion to cool and bond the filter body to the end cap.

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to the field of filter cartridges. More particularly, the present invention relates to length-adjustable filter cartridge end-caps and to filter cartridges which include such length-adjustable end caps. 
     BACKGROUND AND SUMMARY OF THE INVENTION 
     Manufacturers of industrial disposable rigid filter cartridges have for many years essentially standardized filter cartridge diameter and length dimensions and geometries. As a result, the filter cartridges produced by virtually every manufacturer are capable of being employed in another manufacturer&#39;s cartridge housing. Nonetheless, there still exists a need for non-standardized filter cartridges to be provided to the industry. For example, the standardized filter cartridge geometry may not be entirely sufficient for use in large filtration installations and/or to filter heavily contaminated fluids. While higher capacity filter cartridge geometries can be envisioned, their commercial acceptance is limited due to the costs associated with the replacement of existing filter cartridge housings designed for use with the conventional standardized filter cartridge geometries. 
     In now abandoned U.S. application Ser. No. 09/988,222 filed on Nov. 19, 2001, and published under International Publication No. WO03/043714A1 , the entire content of which is expressly incorporated hereinto by reference and will be hereinafter referred to as “the &#39;222 application”, there are disclosed novel length-adjustable filter cartridges having at least one length-adjustable end cap attached to an end of the filter body. The length-adjustable end cap most preferably includes an annular stationary ring member which is attached to one end of the filter body, and a moveable connection member slideably received within the annular stationary ring member so as to be moveable longitudinally relative thereto. 
     While the end caps and filter cartridges disclosed and claimed in the &#39;222 application are entirely satisfactory, some improvements thereto may still be desired. For example, during the manufacture of the filter cartridges by thermally bonding the end caps to the cylindrical filtration medium, the provision of a separate O-ring seal may be problematic thereby leading to production difficulties. As such, it would be highly desirable if the annular stationary ring member that is thermally bonded to the filter medium could be provided with an annular seal that was formed as a one-piece (unitary) structure therewith. Moreover, it would be desirable if such a seal could be thermally protected during the thermal bonding procedures. 
     According to the present invention, length-adjustable end caps and filter cartridges including the same are provided. In preferred embodiments, the length-adjustable end caps include a stationary ring member which includes an annular seal, e.g., a lip seal, a spacer coaxially positioned in spaced relationship with the seal, e.g., spaced below the seal, and a connection member in moveable sealing contact with the lip seal and in a sliding fit with the spacer. The connection member includes an outwardly extending flange having an outer region which includes a sealing arrangement. Most preferably, the lip seal is unitary with the stationary ring member and is a segment of a conical surface and thereby has a proximal edge region which is unitarily joined to the ring member and an opposite distal terminal end which projects downwardly and inwardly into the opening defined by the ring member. The stationary ring member preferably includes a connection flange which defines an annular recess concentric with, but spaced from, the unitary lip seal. The spacer may include an annular spacer ring which is received within the recess. During thermal bonding of the connection flange to an end of a generally cylindrical filter medium, the spacer ring and the end of the filter medium will both be thermally melded to respective adjacent portions of the connection flange. As such, the spacer ring will be integrally fused to the ring member. 
     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 perspective view of a filter cartridge employing a length-adjustable end cap according to the present invention; 
         FIG. 2  is an exploded perspective view of the filter cartridge and length-adjustable end cap depicted in  FIG. 1 ; 
         FIG. 3  is an enlarged cross-sectional view of the filter cartridge and length-adjustable end cap depicted in  FIG. 1 ; 
         FIG. 4  is a greatly enlarged cross-sectional elevational view particularly showing the length-adjustable end cap in accordance with the present invention; and 
         FIGS. 5A-5D  are perspective views of a system and a preferred operational sequence for thermally bonding the end cap to a cylindrical filtration medium to manufacture filter cartridges in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Accompanying  FIG. 1  depicts a particularly preferred filter cartridge  10  in accordance with the present invention. As shown, the filter cartridge  10  includes a generally cylindrical filter body  12  which is closed at one end by a bottom end cap  14 . A length-adjustable end-cap  16  is joined to the upper end of the filter body  12 . 
     The filter body  12  may be formed of virtually any filtration media conventionally employed to filter fluids. Thus, for example, the filtration media may be comprised of pleated sheets of non-woven or woven filter materials which are, in and of themselves, highly conventional in the fluid filtration art. Most preferably, however, the filter body  12  is comprised of a generally cylindrical, 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 media for use as the filter body  12  in accordance with the present invention 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. 2-4 , the length-adjustable end cap  16  includes an annular stationary ring member  22  having an annular connection flange  22 - 1  which is physically attached to the end surface of the filter body  12  most preferably by thermal bonding (i.e., heat welding) in a manner to be described below. 
     A moveable connection member  26  includes a lower cylindrical neck portion  28  and an upper annular flange portion  30 . The flange portion  30  will typically be provided with an elastomeric edge seal  30 - 1  so as to provide a fluid seal between the flange  30  and adjacent structural components of a housing (not shown) in which the filter cartridge  10  is employed. Most preferably, the neck and flange portions  28 ,  30  are formed as a unitary (one-piece) structure and provided with a cross-support  31  so as to increase the structural integrity of the same while yet providing a convenient fixed handle to allow removal/insertion of the connection member  28  relative to the circular interior opening  22   a  defined by the stationary ring member  22  (see  FIG. 2 ). The neck portion  28  is received within, and is slideable with respect to, the annular stationary ring member  22  as shown by the arrows A l  in  FIGS. 3 and 4 . Thus, the entire connection member  26  is slideable along the longitudinal axis of the filter cartridge  10  so that the flange portion  30  thereof may be moved towards and away from the stationary ring member  22 . 
     Important to the present invention is the provision of an annular inwardly projecting flexible lip seal  32  which is formed as a unitary (one piece) structure with the stationary ring member  22 . An annular spacer ring  34  is coaxially positioned in spaced relationship below the lip seal  32  and is seated in a partly conformingly shaped recess  36  (see  FIG. 2 ) formed in a lower region of the connection flange  22 - 1  of the stationary ring member  22 . As will be described below, the spacer flange  34  serves to protect the lip seal  32  during the thermal bonding operation and also serves to ensure that a relatively snug, but sliding, fit is established with the exterior circumferential surface of cylindrical neck portion  28  of the moveable connection member  26 . However, during the thermal bonding operation, a portion of the spacer flange  34  is physically melded with the adjacent region of the connection flange  22 - 1  of the stationary ring member  22  so as to be integrally fused therewith. As such, no separate fluid seal structure is needed as between the spacer flange  32  and the recess  34  of the stationary ring member  22  in which it is seated. 
     The lip seal  22  may be formed of virtually any desired geometric configuration which projects inwardly, and preferably downwardly, so as to constrict the opening  22   a  in which the neck portion  28  is inserted. The lip seal  22  must, of course, be capable of being yieldably outwardly flexed somewhat when in contact with the outer surface of the neck portion  28  so as to thereby maintain sealing contact therewith. Fluid pressure will also serve to urge the lip seal  32  into sealing contact with the neck portion  28  due to the interior of the filter medium  12  being at a greater fluid pressure as compared to the fluid pressure on the exterior of the filter medium  12  (e.g., due to the inside-out flow of the fluid being filtered and the filter drop across the radial thickness dimension of the filter medium). Most preferably, the lip seal  22  is in the form of a generally conical segment oriented in an inward and downward direction (i.e., in a slanted direction from the ring member  22  toward the bottom end cap  14 ). 
     Most preferably, the terminal (lower) end of the neck portion  28  is provided with an exterior circumferential bevel  28 - 1  which assists in the positioning of the neck portion  28  within the stationary ring member. That is, the circumferential bevel  28 - 1  provides a pilot surface to allow the neck portion to be properly positioned with respect to the annular lip seal  32  so that the neck portion may be inserted within the stationary ring member  22 . 
     It is preferred that the moveable connection member  26  be capable of being physically removed from the stationary ring member  22 . For such purpose, the cross-support  31  provides a convenient handle to allow the connection member  26  to be withdrawn from the ring member  22  while the latter remains associated with its supporting structure (for example, a filter housing). Because the weight of the filter body  12  will be substantially increased due to the presence of trapped particulates that have been removed from the filtered fluid during use, it is preferable that the stationary ring  22  also be provided with a diametrically opposed pair of bail ears  22 - 2  which pivotally accept the terminal ends of a semi-circular bail  22 - 3 . Thus, upon removal of the connection member  26 , the remaining structural portions of the filter cartridge  10  may be removed physically from its adjacent supporting structure (e.g., a filter housing, not shown) by manually lifting it with the aid of the bail  22 - 3 . 
     Accompanying  FIGS. 5A-5D  depict a preferred system  50  and technique whereby end caps may be thermally bonded to a cylindrical filter body  12 . In this regard, as shown in  FIG. 5A , the system includes a carriage  52  on which provides a platform to support a nest  54  holding a stationary ring member  22  in an inverted manner. Thus, the bottom surface of the ring member  22  and the spacer ring  34  are exposed to the heating station  56 . Prior to being heated, a generally cylindrical heat shield puck  57  is positioned removably within the interior of the end cap. The heat shield puck  57  serves to protect the unitary lip seal of the ring member  22  during the thermal bonding operation. The carriage  52  is capable of reciprocal rectilinear movements between the heating station  56  and the bonding station  58  so as to shuttle the nest  54  and the inverted ring member  22  therebetween. 
     As shown in  FIG. 5B , with the ring member  22  positioned in the manner depicted in  FIG. 5A , the heating station is moveable into thermal contact with the nest  54  and the inverted ring member  22  held therein so as to melt a portion of the connection flange  22 - 1  which is exposed to the heating station  56 . The exposed portion of the spacer ring  34  is also concurrently melted at this time. After the respective portions of the connection flange  22 - 1  and spacer ring  34  are rendered molten, the heating station  56  is raised and the carriage  52  is shuttled to the bonding station  58  so as to be in coaxial alignment with the filter body  12  held in support structure  60 . Such a state is shown in  FIG. 5C . It will be observed in this regard that the spacer ring  34  has thermally melded with an adjacent surrounding portion of the flange  22 - 1 . 
     An end of the filter body  12  is then brought into contact with the melted region of the flange  22 - 1  by lowering of the support structure  60  along vertical support post  62  as shown in  FIG. 5D . Upon cooling, therefore, the filter body  12  and the connection flange  22 - 1  are thermally melded so as to form an integral structure. Most preferably, the end of the filter body  12  is embedded physically within, and melded to, the flange  22 - 1  to a thickness dimension D (see  FIG. 4 ) of at least about 0.100 inch, and more preferably between about 0.100 to about 0.125 inch. In such a manner, an integral fluid-tight bond is established between the end of the filter body  12  and the flange  22 - 1  associated with the stationary retaining ring  22 . The bottom end cap  14  may be thermally bonded to the other end of the filter body  12  in a similar fashion to that described above with reference to  FIGS. 5A-5D . 
     While the present 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.