Abstract:
A filter assembly ( 20 ) is described that includes a sub-stantially recyclable filter cartridge ( 30 ) inside a pressure vessel ( 22 ). The invented filter cartridge comprises substantially non-pressure bearing walls, except for a pressure-bearing neck ( 44 ) that is adapted to with-stand high pressures preferably in the range of about 500 psi (34,47. 10 5  Pa) from the inside. The walls of the filter cartridge that are incapable of withstanding significant internal pressure are surronded on the outside by a pressure vessel ( 22 ). The invented cartridge need not seal et the pressure vessel, because the cartridge neck ( 44 ) protrudes outside of the pressure vessel ( 22 ) to seal directly to a filter head. The, cartridge preferably includes a quick-disassembly mechanism for allowing quick and non-destructive access to the internal components and media of the cartridge.

Description:
This application claims priority of provisional application Ser. No. 60/159,018, filed Oct. 12, 1999, entitled “Recyclable Filter Cartridge and Housing”. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to filter cartridges for water or beverages, such as those used in water, ice-water, soda pop machines, or other beverage dispensers. Specifically, the invention is a filter assembly, for cooperation with a filter head/manifold, that includes a filter cartridge substantially comprising recyclable components. More specifically, the invention relates to a filter assembly that allows all or substantially all of the surfaces that contact liquid to be periodically removed and recycled, thereby reducing the chance of contamination from long-term use of the surfaces. The filter cartridge is substantially non-pressure bearing, except for the neck of the filter cartridge that extends to form a liquid seal with the head/manifold. A pressure vessel substantially surrounds the filter cartridge for holding and supporting the walls of the filter cartridge under liquid pressure, but the pressure vessel does not necessarily liquid-seal to the filter cartridge or the filter head/manifold. 
     2. Related Art 
     Many filter systems for water or other liquid filtration comprise a filter that cooperates with a “filter head,” which term herein includes a fluid manifold, valve head, or other connection device that directs fluid to and from the filter. The filter typically seals to an internal surface of the filter head so that the liquid entering the filter head flows into the filter, through the filter, then out of the filter to an outlet port in the filter head. In the United States and Canada, water filters are typically required to contain and withstand pressures of about 500 psi without rupturing. In the United States, water systems typically operate in the range of 40-125 psi, and NSF (National Sanitation Foundation) approval ratings typically require a water filter to withstand 4 times the claimed maximum operating pressure, or typically 500 psi. In Canada, safety factors require that water filters withstand about 508 psi for one minute. 
     In one general type of filter system, a disposable pressure vessel connects directly to a filter head. In such a system, when the filter media inside the pressure vessel is spent, the entire pressure vessel must be discarded, including the media contained therein. Disposable pressure vessels are not easily recyclable as there are no easy means to disassemble the pressure vessel. The disposable pressure vessel outer wall is entirely pressure-bearing, that is, it may safely withstand the liquid pressure of the particular system with a large safety margin. Therefore, disposable pressure vessels are more costly to replace because they use more plastic or more expensive materials such as aluminum. Use of disposable pressure vessels is, therefore, costly in terms of filter expense and environmental impact. 
     In alternative filter systems, a disposable filter cartridge may be supplied inside a pressure-bearing housing that connects to the filter head. In such a system, the pressure-bearing housing typically seals to the head using o-rings or other seals and surfaces that are contacted by the liquid being filtered. When the media of the filter cartridge is spent, the filter cartridge is typically discarded and replaced with another cartridge. The conventional filter cartridge has few recyclable components, and, the few recyclable components of the cartridge, such as granular carbon contained in the cartridge, are not removable or easily accessible to a person who might want to recycle. While the filter cartridge is removed and thrown away, the thick-walled pressure vessel is reused. During use, portions of the pressure vessel come in contact with the liquid being filtered, and, therefore, the pressure vessel may become contaminated with bacteria or other unhealthy substances. Because the pressure vessel is continually reused, the contaminated portions remain in use in the filter system and can further the contamination problem in the filter system and in the liquid flowing through it. 
     Therefore, there is a need for an improved filter cartridge, which is substantially recyclable and which, therefore, reduces the resource and environmental created by the filter cartridge. Also, there is a need for an economical and efficient filter cartridge that is designed so that every time the filter cartridge is removed for recycling, the surfaces with the highest chance of being contaminated are also replaced. The filter assembly of the present invention fulfills these needs. 
     SUMMARY OF THE INVENTION 
     The present invention comprises a filter assembly featuring a substantially recyclable filter cartridge. The preferred cartridge includes substantially all components which are recyclable: a cartridge body, cartridge cap, media, media-support and containment pads, and center stem/tubes. The cartridge preferably, but not necessarily, includes an invented mechanism or “latch” for disassembly of the components of the filter cartridge so that the components may be separated and sent to appropriate recycling processes. 
     The invented filter assembly preferably, but not necessarily, includes a pressure-bearing “pressure vessel” that substantially surrounds the filter cartridge except for the protruding neck of the filter cartridge. The pressure vessel comes in close contact with the filter cartridge to safely support and reinforce the non-pressure-bearing filter cartridge, but does not necessarily seal to the cartridge. The filter cartridge neck is pressure-bearing and protrudes out from the pressure vessel to liquid-seal directly to the filter head, so that the entire outer surface of the filter cartridge is dry, that is, not contacted by liquid during filtration, and the entire outward pressure of liquid relative to the atmosphere is directed against the interior walls of the filter cartridge. This liquid pressure is contained inside the filter cartridge neck without reinforcement, while the liquid pressure is contained inside the filter cartridge body by virtue of the surrounding pressure vessel reinforcing the filter cartridge body wall. This is preferably accomplished by a thin-walled filter cartridge body with the neck wall being significantly thicker than the body wall, which results in excellent pressure containment and NSF Safety Factors with a much-reduced amount of total plastic to be recycled after use. 
     Objects of the present invention, therefore, include providing a recyclable filter cartridge for water and beverage filtration, herein including filtering, treatment, or other processing. An object is to provide such a recyclable filter cartridge that greatly reduces the environmental impact of the plastics and other materials used in the filter cartridge, and that is easily disassembled for separation of the various components for proper recycling. A further object is to make the filter cartridge recyclable while minimize the total amount of plastic that must be dealt with in the recycling process. This minimization of total recycled plastic is preferably done by providing a thin filter cartridge outer wall except for the relatively small pressure-bearing neck. Another object is to provide a filter cartridge system in which all or substantially all of the surfaces that liquid contacts after leaving the filter head and prior to returning to the filter head are removed from the system when the filter cartridge is removed for recycling. Thus, the liquid-contact surfaces are filter cartridge surfaces rather than pressure vessel surfaces, and are replaced each time the filter cartridge is replaced. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a top perspective view of one embodiment of the invented filter assembly. 
     FIG. 2 is a top view of the filter assembly of FIG.  1 . 
     FIG. 3 is a cross-sectional view of the filter assembly of FIGS. 1 and 2, viewed along the line  3 — 3  in FIG. 2, with a dust cap installed. 
     FIG. 4 is an enlarged detail cross-sectional side view of the top end of the filter assembly, which is the end circled in FIG.  3 . 
     FIG. 5 is an exploded side perspective view of the pressure vessel, which comprises a pressure body and pressure cap of the filter assembly of FIGS. 1-4. 
     FIG. 6 is an exploded side perspective view of the filter materials, media supports and filter pads, of FIGS. 1-4. 
     FIG. 7 is an exploded side perspective view of the central stem, optional liquid bypass sleeve and o-rings, of the cartridge of FIGS. 1-4. 
     FIG. 8 is an exploded side perspective view of the cartridge body, cartridge cap including inlet tube member in the cap, sealing members, and dust cap of the embodiment of FIGS. 1-4. 
     FIG. 9 is a close-up perspective view of the exterior of the embodiment of a cartridge cap installed in a pressure vessel cap, according to the invention, with neck protruding through and up from an opening in the pressure vessel cap. 
     FIG. 10 is a perspective view of the pressure vessel cap of the embodiment of FIG.  10 . 
     FIG. 11 is a perspective view of filter cartridge cap of FIG. 9, shown separate from the pressure vessel cap. 
     FIG. 12 is an exploded perspective view of the cartridge body and cartridge cap of FIGS. 3 and 8, separated to illustrate one embodiment of a tab and slot connection system for snapping the body and cap together. 
     FIG. 13 is a perspective view of the top end of the filter cartridge of FIGS. 3,  8 , and  12 , illustrating the cartridge cap snapped into the cartridge body. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the Figures, there is shown one embodiment, but not the only embodiment, of the invented filter assembly  20  which includes filter cartridge  30  inside pressure vessel  22 . The invented assembly  20  comprises a pressure vessel  22  which is visible as substantially the exterior surface of the assembly, and which has an aperture  24  through which the neck  44  of the filter cartridge  30  extends to seal directly to a filter head. The invented assembly  20  may be adapted for being secured to the filter head by several different ways, for example, the preferred bayonet mount  32  on the pressure cap  46 , a threaded mount, or other connection means. Preferably, the invented pressure vessel mechanically connects to the filter head, by such a connection means, but does not fluidly connect, that is, it does not fluidly seal, to the filter head. The filter assembly of the invention may be adapted to cooperate with various filter heads, by adapting the connection means and the size and shape of the neck, which preferably comprise the filter cartridge liquid inlet and outlet passages. The preferred embodiment of the filter assembly  20  shown in the drawings may cooperate with a filter head such as the type illustrated by the systems in U.S. Pat. No. 4,857,189 and Design 356,625, and, once the disclosure of the present invention is viewed, one of skill in the art will be able to construct a filter head that will operatively connect with the invented filter cartridge. The cartridges conventionally built for such systems as shown in U.S. Pat. No. 4,857,189 and Design 356,625 are of the type described in Related Art as a non-recyclable filter with its outer wall being entirely pressure-bearing. 
     In the preferred embodiment, fluid flows via the filter head into the central axial passage  134  in the filter cartridge  30  via an inlet end  33  of inlet tube member  34  out the bottom of the central axial passage, up through the filter media  36  (which may comprise one or more media, empty spaces, pads, supports, etc), and out of the filter cartridge  30  through a concentric annular passage  38  around the inlet tube member  34 . In the preferred embodiment, shown to particular advantage in FIG. 3, there are three different media in series  136 ,  137 ,  138 , but other arrangements may be used. The filter cartridge may optionally include a liquid bypass system  35  for allowing some liquid flowing down the inlet tube member  34  to exit the central axial passage  134  part way down the tube to flow directly to, for example, the top bed  138  of media rather than flowing through all three beds of media. The liquid bypass system  35  may include one or more holes of a diameter sized to let a particular amount of liquid bypass the lower media, or may be other systems. The liquid bypass system  35  design is optional and is not required for the invented apparatus or practicing the invented filtration methods. 
     The filter cartridge  30  extends up through a central opening (aperture  24 ) in the pressure cap  46  and seals to the filter head (not shown) at two locations, at o-ring  42 ′ (shown in FIGS. 3 and 8, in groove  42 ) and at a small diameter o-ring  52 ′ (shown in FIGS.  3  and  8 , in groove  52 ). This way, the neck provides and holds both seals necessary to fluidly connect the filter cartridge to the head using the concentric, annular inlet and outlet system of the filter cartridge. That is, as the preferred embodiment is arranged, the inlet to the filter cartridge is sealed at seal location  52  and the outlet of the filter cartridge is sealed between o-rings  42 ′ and  52 ′. 
     The pressure vessel  22  comprises a pressure body  54 , which is a generally cylindrical member with a closed end and an open end, and a pressure cap  46  that connects to the pressure body across its open end. The connection may be a threaded connection, as shown in the drawings, but may be other designs. The pressure body  54  preferably has axial exterior ribs  56  for strengthening the body. The pressure cap  46  has top aperture  24  centered along the central longitudinal axis of the pressure vessel  22  for receiving the protruding neck  44  to an extent that allows the filter cartridge to mate appropriately to the head with the sealing locations  42 ,  52  well above the pressure cap. 
     Inside the interior space of the invented pressure vessel  22  is placed the invented filter cartridge  30 . The cartridge  30  comprises a cartridge body  64  and a cartridge cap  66  that connect preferably by a snap connection  68  but may be connected by other means. The connection of cartridge body  64  and cartridge cap  66  preferably includes an o-ring  8  or other liquid-sealing mechanism to prevent liquid from leaking out between the cartridge body and cartridge cap. 
     The cartridge body  64  is generally cylindrical with a closed bottom and an open top across which the cartridge cap  66  extends. The cartridge cap  66  includes radially-outwardly-protruding tabs  65  that are spaced circumferentially around the bottom region of the cartridge cap  66 . The tabs  65  snap into circumferentially-spaced slots  67  near the top of the cartridge body for connecting the body and cap after the cartridge internals and media have been installed. The top end of the cartridge cap includes cylindrical neck  44  of about half the diameter of the largest diameter of the cap and with adaptation on its outer surface for holding an o-ring at circumference groove  42 . 
     The preferred internals and media of the filter cartridge comprise one or more filter or treatment media  36 , a top media felt pad  82 , media separator  182 , separator felt pad  282 , a central tube (“stem”  84 ), the inlet tube member  34  connected to stem  84  and having inlet end  33 , and o-rings  42 ′,  52 ′, bypass tube  37 , o-ring  108  sealing bypass tube  37  to inlet tube member  34 , and is bypass system  35  is included, o-ring  108 ′ sealing bypass tube  37  to stem  84 , and o-ring  109 . If bypass system  35  is excluded, the tube member  34  could be adapted to seal to stem  84 . The central stem  84  lies on radially-formed ribs  86  on the interior bottom wall of the cartridge body  64 . Ribs  86  create a fluid path from the inside of stem  84  into media  36 . The stem  84  upends from the ribs  86  to extend through the interior space and through the pads, media separators, and media  36  contained therein to seal with the inlet end  33 . The media  36  may be any single media or combination of media desired for liquid/beverage treatment, filtration or conditioning. Media  36  are preferably granular activated carbon and ion exchange resin, and this media choice may be taken into account by one skilled in the art when selecting the supports and pads below, between, and above the various media. 
     Inside and coaxial with inlet tube member  34  is an optional bypass sleeve  37  with a lower portion  37 ′ that connects to stem  84  and may optionally have holes, o-rings, or other structure for providing a liquid bypass system. The structure  133  shown at the top of the sleeve  37  and in the top inside view of sleeve  37  in FIGS. 12 and 13 may cooperate with the dust cap C shown in FIGS. 3,  4 , and  8 . Dust cap C may be used to keep the inlet and outlet of the cartridge clean, and, optionally, may cooperate with structure  133  to allow adjustment of the sleeve  37  to adjust the liquid bypass by rotating the sleeve. As stated above, the liquid bypass is optional and may be closed, blocked off or eliminated. 
     From a fluid flow point of view, the fluid enters the inlet end  33  (and through the interior of sleeve  37 ) and flows down into the stem  84 , and out through radial ribs  86  in the bottom of cartridge body  64  to the media  136 . As mentioned above, a liquid bypass system  35  may optionally be incorporated to allow a portion of the liquid to flow only through a portion of the media zones. From the media  136 , the liquid flows generally axially upwards through the other media  36 , supports and pads, through apertures in the inlet tube base and into the annular space  38  between the inside surface of the cartridge cap  66  and the outside surface of the inlet end  33 . Annular space  38  may include ribs  71  running axially in the annular space  38  to stabilize the inlet end  33  relative to the cartridge cap. 
     As can be seen to best advantage in FIG. 3, the cartridge  30  fits closely inside the pressure vessel  22 , and the pressure vessel  22  acts as a reinforcing shell around substantially all of the cartridge  30 . Unlike many conventional filter cartridges, however, the cartridge  30 , particularly neck  44 , of the present invention extends at its top end out of the pressure vessel to seal directly to the filter head. The pressure vessel and filter cartridge, therefore, need not liquid seal to each other, although the inventor envisions adequate embodiments that would include sealing between the filter cartridge and pressure vessel. In the preferred embodiment, liquid does not flow or reach between the pressure vessel cap and the cartridge cap, that is, there need be no liquid seal in the general location L where the two caps  46 ,  66  contact or come near to each other near the aperture  24 . Also, the cartridge body  64  need not seal to the inner surface of the pressure vessel body  54 , but should be closely adjacent. 
     The various components of the cartridge  30  are preferably recyclable. Specifically, the cartridge body  64 , cap  66 , stem  84 , spacer  86  are preferably recyclable polyethylene or polypropylene. The various media  36  are preferably recyclable carbon, resin, or other material. The internal pads and media supports are preferably made of recyclable materials such as polyurethane or polypropylene. The o-rings may not be recyclable, but these are preferably the only components that are not, and they are very small, easily removed and should be removed and discarded to prevent back-contamination with any bacteria or pathogens that might be present on them or on the o-ring lubricating oil. 
     The absolute wall thickness of the neck  44  is important as it is critical to the filter cartridge and the filter assembly, in general, meeting safety requirements for withstanding water pressure of the system to which they are connected. For example, to withstand a 500 psi test, the polypropylene neck wall thickness T preferably greater than or equal to 0.125 inch in thickness, while the filter cartridge body wall preferably only about 0.060 inches (typically in the range of 0.050-0.070) in thickness. Therefore, the body wall typically is less than about half the thickness of the neck thickness. Other thicknesses may apply for various materials and pressure requirements. The neck preferably is thick-walled from the top  144  of the neck, all the way through the aperture  24  and for a slight distance down into the pressure vessel to neck bottom  244 , to prevent rupturing of the neck in the vicinity of the aperture  24 . The inlet tube member  34  wall, which also extends up coaxially with the neck wall out of the pressure vessel, does not need to be of a thickness comparable to the neck wall, because the inlet tube is not exposed to a large pressure difference as the neck wall is. The neck wall withstands the full pressure difference between the water in the neck and the outside atmosphere, while the inlet tube has water both inside it (inlet water) and outside it (outlet water) and the pressure difference between the two water streams is only the pressure drop through the filter cartridge. 
     Therefore, one may describe the preferred invented filter cartridge as having an exterior wall having a high strength portion and a low strength portion. In the preferred embodiment, the exterior wall is the entire outer wall of the filter cartridge including the body and cap. The high strength portion is defined as being adapted to withstand pressure of greater than 475 psi, and is preferably a neck that extends up from one end of the filter cartridge. The low strength portion is defined as being adapted to withstand only minimal pressure, for example less than 10 psi, and is preferably the entirely of the outer wall of the filter cartridge except the above described neck. Also, the term “pressure bearing” in this Description and Claims means positioned and capable of bearing by itself (without significant reinforcement) the pressure of the fluid in the process in which it is being used. The term “non-pressure bearing” means that a part or portion of a structure is not positioned in a place where it will be exposed to significant pressure, that is, not more than a negligible amount, and especially not more than about 10 psi. 
     One may see from this description and the drawings, that the filter assembly, comprising the filter cartridge and the pressure vessel, may be removed from the head and the recyclable filter cartridge  30  may easily be removed from the pressure vessel by unscrewing or otherwise disconnecting the pressure cap from the pressure body. Then, the cartridge may be recycled after being disassembled as described below, for example. Other mechanisms for easy opening of the filter cartridge may be used, and these are called herein “latch mechanisms” as they allow closing of the filter cartridge after filling of the cartridge body with media, and then allow opening of the filter cartridge without excessive force or destruction of the body or cap after use. In this Description and the Claims, latch does not imply that no cutting or removal of filter cartridge material may be done to unlatch parts of the exterior wall, but preferably only cutting or removal of a tab or other small portion of a latch is done rather than destruction by impact, sawing, or slicing the body. Preferably, two parts of the low strength portion of the filter cartridge exterior wall are the parts that are “latched” and “unlatched,” at a seam or connection  68 , for example. When the preferred cartridge is removed from the preferred pressure vessel, the cartridge takes with it all the surfaces and seals that have contacted liquid on the “filter assembly side” of the process. Thus, potentially contaminated surfaces and o-rings are removed periodically rather than remaining with the reused pressure vessel. Some contamination may reside on the “filter head side” of the process, because the filter head is not recycled or replaced, but the total head surfaces as typically small in area, and, if the o-rings are removed with the filter cartridge, the chances of o-ring lubricant contamination, for example, are minimized. 
     In order to disassemble the cartridge  30 , special adaptation is preferably included to allow separation of the components of the cartridge  30  without crushing or cracking the cartridge. Preferably, the adaptation is such that accidental separation is unlikely, but purposeful separation prior to recycling is easy with the correct tool. Preferably, the adaptation comprises a snap-in tab and slot system, illustrated to best advantage in FIGS. 12-13, or other separation system for opening the cartridge, preferably without cracking, crushing, or drilling through the cartridge housing. The tabs  65  are typically formed integrally with the cartridge cap  66  near its lower end. The cooperating slots  67  near the upper edge of the cartridge body  64  receive the tabs  65  in snap-fit manner, to semi-permanently connect the cap  66  to the body  64 . The outer perimeter of the lower end of the cap  66  includes cut-away portions  69  directly above each tab  65  so that the tab and slot connection may be reached by a tool. When the user of recycler wishes to disassemble the filter cartridge  30 , he/she may slide a knife or sharp tool down between the cap  66  and the body  64  directly above the tab and slice downward on the tab to remove enough of the tab to release the body from the cap. This, or other types of separation, allow a person or equipment to reach inside the cartridge, to remove the internals and the media from the cartridge for recycling of the internals and media as well as the external cap and body components. 
     Although this invention has been described above with reference to particular means, materials and embodiments, it is to be understood that the invention is not limited to these disclosed particulars, but extends instead to all equivalents within the scope of the following claims.