Abstract:
A filtration device having a base portion including a sump which has an inlet and an outlet and which accommodates a filter element. The base has a reception port for receiving the filter element. The sump optionally is enclosed by a housing which is engaged to a portion of the base.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The subject application is a continuation of the U.S. application Ser. No. 09/169,204 filed Oct. 8, 1998, which is now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The subject invention relates to fluid filtration apparatus, and more particular, to a counter top water filtration unit for domestic use. 
     2. Background of the Related Art 
     Due to run-off and environmental contamination, drinking water in most areas of the world contains appreciable amounts of dissolved chemicals and suspended particulate material. A number of chemicals and particulates that may be found in drinking water have been associated with possible adverse physiological effects. Other chemicals and particulates in drinking water have been associated with less than desirable taste and sensory perceptions, such as “clouding” of the water or “souring” of the water. Chemicals and particulates in a water source may also lead to undesirable rings in appliances and commodes using large amounts of water, and may result in unsightly films being placed on items washed in the water. In the estimation of many persons, municipal water treatment plants often fail to adequately deal with these problems. In order to improve water quality, many residences and businesses now employ on-site water filters to filter water streams consumed therein. 
     Until relatively recently, most on-site water filters were typically designed to be mounted in a permanent housing coupled to a water stream, such as in series with a pipe. Such permanent housings were often located in relatively poorly accessible locations (such as under a sink or in the basement) and often required special tools in order to gain access to the filter residing in the housing (such as a wrench). While on-site permanent filters are often perceived to remediate the water sufficiently for everyday uses, such as washing dishes and clothes, there is a large and growing number of people who demand cleaner and more tasteful water for internal consumption. Rather than adding new types of filters into permanent-type on-site water filter housings or increasing the number of such housings, in order to provide for a more convenient manner of coupling filters to water streams and of changing filters, so-called “countertop filtration units” were developed. “Countertop filtration units” are portable filter apparatuses dimensioned to fit on a standard household countertop and adapted for coupling to a fluid flow outlet spigot, such as a faucet. Such units are generally primarily intended for domestic use to filter impurities out of tap water. The unit may be placed on a counter adjacent to a sink. 
     Countertop filtration units are generally fabricated from plastic and/or metal. Conventionally, these units comprise a base upon which a “sump”, such as cup or cover, which acts as a sump, is placed and in which the filter cartridge is housed. The “sump” is generally screwed into the base wherein a seal typically exists to permit fluid tight sealing. The filter in conventional counter filtration units is changed by removing the “sump”, pulling out the spent filter, inserting a new filter into the “sump” and reattaching the same to the base. The “sump” has an inlet opening to enable an entrance of the fluid into the “sump” and through the filter materials. The “sump” further has an outlet opening to enable the fluid to be discharged from the “sump” after it has coursed through the filter. The unit may further be equipped with a valve to selectively divert the fluid flowing to the filter cartridge. 
     Filtration is the process of separating particles from a fluid suspension (liquid or gas) by use of a porous medium or by means of a medium possessing chemical properties, such as hydrophobicity, electrostatic charge, etc., which permit such medium to interact and hold the particles which are to be separated from the fluid while permitting the fluid to pass there through. In conventional filtration, the filter medium retains most of the suspended particles which are filtered on or within itself, but allows the fluid being filtered to pass through unimpeded. Flow across the filter medium is generally achieved by the application of a driving force, usually in the form of a static pressure difference across the filter, which may be generated, for example by external pressure applied upstream, a vacuum applied downstream, gravity, or other force. 
     Filters used in countertop filtration units are designed to be disposable. One commonplace type of disposable filter is in the form of a solid porous cylinder having a hollow center. When such filters are employed, the fluid to be filtered flows radially through the wall of the cylinder between its exterior and hollow core. Such filters are generally capped at each end with a boundary sealing-cap to permit sealing between the filter and the housing in which it is placed in such a manner as to assure that only fluid having passed through the wall of the filter cylinder and into the hollow core is permitted to exit from the filtration unit. Typically, countertop filtration units employ filters fabricated from granular activated carbon. Granular activated carbon is useful for removing organic chemicals such as chlorine, hydrogen sulfide, pesticides, herbicides, phenol, chlorophenol and hydrocarbon from water. Other filter elements may be employed as well to help remove sediments such as rust and other particles. Silver salts are sometimes added to the filter material to combat bacterial growth. Ion exchange resins are also used in such filtration units. 
     While carbonaceous filter elements are known to be good at removing contaminants that affect taste, odor of the filtrate, and visible particulate matter, such filters generally are not fine enough to remove bacteria or viruses. 
     There are numerous microporous elements available for removing bacteria and viruses. Among these elements are hollow fibers having micropores coursing through the fiber walls. Typical microporous hollow fibers include Celgard™ manufactured by Questar division of Celanese Corporation. Such hollow fibers offer controlled and relatively uniform porosity as compared to many asymmetric ultrafiltration and microfiltration membranes. Fiber construct is such that there is high membrane surface area-to-volume ratio. The pores in the fibers form tortuous, interconnected channels leading from one surface of the fiber to the other. The pores of these hollow fibers allow the flow of gases and vapors but block passage of many bacteria, colloids and other submicron particles and solutes. Fibers having pores of 0.05 microns or less are capable of filtering most viruses. In order to assure passage of the fluid through the fiber pores rather than through any end, such fibers are generally potted in an epoxy or other standard potting material at both ends of the fiber. 
     Countertop filter cartridges conventionally can be classified in either of two types: encapsulated and drop-in. Encapsulated cartridges incorporate the “sump”, such that the “sump” must be replaced with the filter element. The advantages of encapsulated cartridges are that they are user friendly and the seal between the base and “sump” are replaced each time. There also are advantageous to manufacturers in that they generally require proprietary cartridge replacement. Drop-in cartridges on the other hand are replaced independently of the “sump”, the “sump” being re-used each time. The advantage of the drop-in cartridges over encapsulated cartridges is that such cartridges are generally cheaper. 
     There are problems associated with countertop filtration units employing either encapsulated or drop-in filter cartridges. Both systems require removal of the “sump” from the unit in order to replace the filter. Removal of the “sump” from the base is often less than convenient, given that the “sump” is generally screwed into the base by means of relatively large threads. Further, as most countertop filtration units house the “sump” in an external housing, designed in part to hide the rather non-aesthetic “sump” and inflow/outlet tubes, the external housing must also be removed before access to the “sump” may be had. As the process involved in removing and changing either encapsulated or drop-in filter cartridges is relatively complex, fluid filtration quality often suffers due to less than optimal replacement of the filter. In regard to “drop-in filter cartridges” such filters suffer not only from the problems associated with ease of access to, and replacement of the filter element, but also with respect to the need to continually replace the seal between the “sump” and the base. On the other hand, “encapsulated cartridges,” due to the inherent cost of the “sump” which is replaced with each filter change, can be far less than economic. 
     There is a need, therefore, for an improved countertop filtration unit which permits easy replacement of filter elements and aids in assuring adequate sealing between the “sump” and base. 
     SUMMARY OF THE INVENTION 
     The present invention provides an improved countertop filtration unit which provides user-friendly filter cartridge replacement and aids in assuring adequate sealing between the sump and base. The present invention provides a countertop filtration unit having a sump integral with the unit&#39;s base, the base having a reception port for filter element engagement into, and disengagement out of, the sump. 
     By “sump” it is meant any reservoir serving as a receptacle for liquids which is constructed so as to able to withstand the fluid pressures to which it is exposed. By “base” it is meant any housing on which the sump rests and which is designed to typically interface with the surface upon which the filter unit is to be placed. By “reception port” it is meant any communication area positioned in the base permitting reception of a filter cartridge into the area and out of the area. By “end-cap” it is meant a substantially solid piece of material placed at the end of a filter element which is dimensioned so as to at least seal the greater portion of the surface area of an end of the filter element. By “adapter” it is meant any structure for joining one element to another. By “fluid adapter,” it is meant a structure for allowing communication of a fluid stream with the filter element, typically by means of fluid conduits, such as tubing. By “filter element” it is meant any combination of materials used to filter out suspended or dissolved particles or chemicals from a fluid. By “microporous hollow fibers” it is meant an elongate structure having a central void constructed such to have a relatively high membrane surface area-to-volume ratio and porous walls wherein the pores of the wall lead from one surface of the fiber to the other surface of the fiber and are substantially of such size as to be able to block the passage of submicron particles and organisms. By “external housing” it is meant any housing for surrounding and enclosing the sump. By “inlet” it is meant an opening for intake of fluid, whereas by “outlet” it is meant an opening for the out-take of fluid. 
     One embodiment of the present invention includes a filtration unit which comprises a base portion including a sump for accommodating a filter element and a reception port for receiving the filter element. The sump has an inlet and an outlet. Preferably the reception port is defined in a bottom surface of the base portion. The unit may further include an external housing portion for engaging the base porition to enclose the sump. Preferably the end cap includes a camming surface for cooperating with a complementary surface in the base portion to facilitate engagement of the end cap and the reception port. 
     Preferably, the filtration unit has the sump integral with the base portion, and the reception port is defined in a bottom surface of said base portion. Preferably, the filter element to be received in the reception port is dimensioned and configured for accommodation within said sump, and is constructed so as to have an end cap dimensioned and configured for engaging the reception port. The end cap may include a camming surface for cooperating with a complementary surface in said base portion to facilitate engagement of the end cap and the reception port. Preferably, a first seal is associated with either or both the reception port and the end cap so as to effect a seal between the end cap and the base portion. A second seal may further be associated with either one end of the filter element and/or the interior surface of the sump to effect a seal between said filter element and the sump. The filter element may be defined at least in part by an extruded carbon block or by hollow microporous fibers. Preferably, the filter element is a composite filter element including first and second filtration media, wherein the first filtration media comprises an extruded carbon block and the second filtration media comprises hollow microporous fibers. 
     Still another embodiment of the present invention includes a filtration device which comprises a filter element having an end cap provided at a first end thereof, a base portion including an integral sump for accommodating the filter element and a reception port for receiving the filter element and engaging the end cap; and a housing portion for engaging the base portion to enclose said sump. 
     In a preferred embodiment the sump is formed monolithically with the base portion. It is preferred that the reception port be defined in a bottom surface of the base portion. While the end cap may be engaged to the base by any of the many attachment mechanisms known in the art, in one embodiment, the end cap includes camming lugs for cooperating with a complementary camming surface in the base portion to facilitate engagement of the end cap and the reception port. It is preferred that a first seal be associated with at least either the reception port and/or the end cap to effect a seal between the end cap and the base portion. A second seal may be associated with at least one of an end portion of said filter element and an interior surface of the sump to effect a seal between the filter element and the sump. The filter element may be defined at least in part by an extruded carbon block or by hollow microporous fibers. Preferably, the filter element is a composite filter element including first and second filtration media, wherein the first filtration media comprises an extruded carbon block and the second filtration media comprises hollow microporous fiber. 
     And yet another embodiment of the present invention includes a filter device for housing a filter element having an end cap associated with an end thereof, which comprises a base portion for accommodating the filter element, the base portion being integral with a sump having an inlet and an outlet, wherein the base portion encompasses a void through which the filter element may be positioned in said sump, and the base portion surrounding said void includes an engagement surface complementary to the surface of the end cap for engaging the filter element; and a housing portion for engaging the base portion to enclose the sump. 
     These and other unique features of the system disclosed herein will become more readily apparent from the following description, the accompanying drawings and the appended claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     So that those having ordinary skill in the art to which the disclosed system appertains will more readily understand how to make and use the same, reference may be had to the drawings wherein: 
     FIG. 1 is a perspective view of a countertop filter unit coupled to an adapter assembly for attaching the filter unit to a fluid stream; 
     FIG. 2 is a perspective view of a filter unit assembly embodiment of the present invention; 
     FIG. 3 is a perspective view of an end-cap for engagement into the base portion of the filter unit assembly of FIG. 2; 
     FIG. 4 is a cross-sectional view of the end-cap of FIG. 3 cut along axis  4 — 4 ; 
     FIG. 5 is an interior perspective view, partly in section, of a filter element endcap/base coupling mechanism of an embodiment of the present invention; 
     FIG. 6 is a cross-sectional view of the assembled filter unit embodiment of FIG. 2; 
     FIG. 7 is a perspective view of the assembled filter cartridge of FIG. 2; and, 
     FIG.8 is an exploded view of the filter cartridge shown in FIG. 2 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention overcomes many of the prior art problems associated with countertop filtration units The advantages, and other features of the system disclosed herein, will become more readily apparent to those having ordinary skill in the art from the following detailed description of certain preferred embodiments taken in conjunction with the drawings which set forth representative embodiments of the present invention and wherein like reference numerals identify similar structural elements. 
     Referring to FIG. 1, there is shown a perspective view of a countertop filter unit  10  coupled through one or more conduits  18 ,  20  to an adapter assembly  16  for attaching the filter unit to a fluid stream. Countertop filter unit  10  includes a base  14  on which is mounted an external housing  12 , base  14  and external housing  12  defining the exterior of countertop filter unit  10 . Adapter assembly  16  is designed to be connected to fluid flow, as from, for example, a sink, by means of connector  26 . Fluid flow entering the adapter through connector  26  may be directed to countertop filter unit  10  by way of conduits  18 , or through direct throughput opening  24  in adapter  16 , by stopcock  22 . 
     Now referring to FIG. 2, there is shown a perspective view of a filter unit assembly embodiment of the present invention. Base  14  includes sump  32  which is dimensioned to fit a filter cartridge, generally designated in its component parts as  50 . Sump  32  is shown to have inlet and outlet,  28  and  30 , for admitting to, and removing from, sump  32  fluid. Inlet  28  and outlet  30  are connected to the exterior of filter unit  10  through conduits  20  and  18 , respectively. Sump  32  is generally surrounded by cover  12  and may be connected to the same through connecting structure, such as, but not limited to, screws  36  and threaded receptacles  34 . A first panel  38  may be positioned over screws  36  to provide for a more aesthetic cover  12  exterior. Cover  12  may further house therein a power source  40  for powering any electronics associated with the filter, such as a timing clock (not shown) to indicate whether filter change is recommended. A second panel  42  may be positioned over power source  40  to provide for a more aesthetic cover  12  exterior. Base  14  may be equipped with stand-offs  74  (See FIG.  5 ). 
     Filter cartridge  50 , or any other filter cartridge adapted to sealingly fit within sump  32 , may be utilized in countertop filter unit  10 . Filter cartridge  50  is comprised of two filter elements, one comprising a jacket of carbonaceous material,  44 , the other comprising a U-shaped bundle of hollow, microporous fibers  48  as a preferred embodiment. The jacket of carbonaceous material  44  may be formed by an extrusion process. Hollow, microporous, fiber bundle  44  is housed concentrically within the cavity  56  formed by carbonaceous jacket  44 . Hollow, microporous, fiber bundle  48  is formed by potting hollow, microporous fibers in the bottom portion of upper cage  82  (See FIG.  8 ). Upper end-cap  52  has a sealing neck  62  for sealingly connecting to internal sump collar  78  as shown in FIG.  6 . Sealing neck  62  preferably is fitted with upper seal  54  to aid in complete sealing between sealing neck  62  and internal sump collar  78 . Filter cartridge  50  is further fitted with a lower end-cap  46 . 
     As shown in perspective view in FIG. 8, the U-shaped bundle of hollow, microporous fibers  48  may be contained in a cage  82 , cage  82  and hollow, microporous fibers being pulled in upper end-cap  52 . Cage  82  is positioned within cavity  56  formed by carbonaceous jacket  44 . 
     As shown in perspective view in FIG. 3, and in cross-sectional view in FIG. 4 (along  4 — 4  line of FIG.  3 ), lower end-cap  46  has an imperforate annular wall  61  extending from an imperforate base wall  62  that defines recessed portion  64  for receiving one end of carbonaceous jacket  44 . Lower end-cap  46  further has positioned therein centering collar  66  dimensioned so as to fit into cavity  56  of carbonaceous jacket  44 . Centering collar  66  aids in centering carbonaceous jacket  44  in lower end-cap  46 . Lower end-cap  46  further houses lower seal  58  axially disposed between the annular wall  61  and the engagement structure ledge  60  for aiding in complete sealing between lower end cap  46  and upper surface  76  (See FIG. 5) of base  14 . Lower end cap  46  is further constructed with engagement ledge  60  for engaging threaded shoulders  72  (See FIG. 5) of base  14 . 
     The manner of engaging assembled filter cartridge  50 , illustrated in FIG. 7, into base  14  of countertop filter unit  10  is shown in FIG.  5 . Upper end-cap  52  of assembled filter cartridge  50  is inserted through base opening  70  from inferior base surface  68 . Lower end-cap  46  is subsequently coupled to base  14  by engaging engagement ledge  60  along engaging threaded shoulders  72  so as to affect axial translation of the filter cartridge  50  relative to base  14 . Preferably, once lower end-cap  46  is rotated into its locked position, lower end-cap  46  will be flush with base  14 . Coupling may be through means of interlocking camming surfaces. Preferably, engagement is such that lower seal  58  is sealing engaged with respect to superior base surface  76 . Preferably simultaneous with coupling of lower end-cap  46  with base  14 , upper end-cap  52  is also being sealing coupled to the internal surface of internal sump collar  78 . Lower end-cap  46  may also be fabricated to have slot  59  in its inferior surface to permit insertion of instruments into slot  59  to ease turning of filter cartridge  50  and thus to engage coupling. 
     Now referring to FIG. 6, there is shown a cross-sectional view of the assembled filter unit embodiment of FIG.  2 . As illustrated, fluid enters through conduit  20  through inlet  28 . Fluid circulates about carbonaceous filter element  44  and under pressure crosses the walls of carbonaceous element  44  entering into carbonaceous element cavity  56 . Fluid in carbonaceous element cavity  56  is forced by pressure to exit through hollow, microporous fiber bundle  48  and then through upper end cap neck  62  to outlet  30 , upper end cap neck  62  being sealingly connected to sump outlet sealing part  78  of sump  32 . Outlet  30  is attached to conduit  18  from which filtered water may be obtained. Microporous fiber bundle  48  may be unhoused in cavity  56 , or as illustrated, enclosed within a housing, for example, cage  82 , which preferably is perforated, and more preferably disposed so as to permit exposure of more than 40% of the total surface area of the fiber bundle to the surrounding fluid. 
     While the invention has been described with respect to preferred embodiments, those skilled in the art will readily appreciate that various changes and/or modifications can be made to the invention without departing from the spirit or scope of the invention as defined by the appended claims.