Patent Publication Number: US-2009230034-A1

Title: Filter cartridge

Description:
RELATED APPLICATION 
     This application claims priority under 35 U.S.C. §119 (e) to U.S. Provisional Patent Application No. 61/036,616 filed on Mar. 14, 2008. The entire disclosure of this provisional application is hereby incorporated by reference. If incorporated-by-reference subject matter is inconsistent with subject matter expressly set forth in the written specification (and/or drawings) of the present disclosure, the latter governs to the extent necessary to eliminate indefiniteness and/or clarity-lacking issues. 
    
    
     FIELD 
     A filter cartridge comprising filter media with an inner radial surface defining an outlet chamber therewithin and an outer radial surface defining an inlet chamber therearound. 
     BACKGROUND 
     A refueling system for an aircraft can generally comprise a hydrant (or other almost continuous source of fuel), and a vehicle that transfers fuel from the hydrant to the aircraft. A transfer vehicle (e.g., a cart or truck) can comprise, for example, a supply hose from the hydrant to its accouterment bank, and a delivery hose from the bank to the aircraft. The accouterment bank can comprise, among other things, a filter assembly for filtering the fuel prior to its delivery to the aircraft. 
     SUMMARY 
     A filter cartridge comprises a fuse element that shuts the fuel exit should the filtering media become clogged or otherwise fail to pass fluid at an acceptable flow rate. The fuse element comprises a plastic poppet part that “blows” in response to the inlet-outlet pressure differential reaching a range corresponding to a filter-clogged scenario. The fuse element can be constructed without electrical circuits, biasing springs, complicated mechanical linkages, and/or precision instrumentation. Thus, the fuse element can be economically incorporated into a replaceable filter cartridge and, once the poppet has “blown”, it can be discarded with the filter cartridge and replaced. 
    
    
     
       DRAWINGS 
         FIG. 1  is a schematic diagram of a refueling system for an aircraft. 
         FIGS. 2A and 2B  are side and top views, respectively, of a filter assembly for the refueling system. 
         FIG. 3  is a side view (with the filter media partially removed) of a fuse-filter cartridge of the filter assembly. 
         FIGS. 4A-4C  are schematic views of the operation of the cartridge&#39;s fuse element, and  FIGS. 4D-4J  are close-up views take from these schematics. 
         FIG. 5  is a perspective sectional view of the fuse element (and adjacent regions of a filter element) without its movable poppet part. 
         FIGS. 6A and 6B  are perspective views of the movable poppet part. 
     
    
    
     DESCRIPTION 
     Turning now to the drawings, and initially to  FIG. 1 , a refueling system  10  for an aircraft  12  is schematically shown. In this system  10 , aviation fuel from a hydrant  14  (or other almost continuous source) is supplied to a transfer vehicle  16  (e.g., via a supply hose  18 ) which then delivers the fuel to the aircraft  12  (via a delivery hose  20 ). The vehicle&#39;s accouterment bank  22  includes, among other things, a filter assembly  100 , which filters the fuel prior to its delivery to the aircraft  12 . 
     The filter assembly  100  is shown in  FIGS. 2A and 2B  isolated from the rest of the refueling system  10 . The filter assembly  100  includes a housing  200  and at least one filter cartridge  300  installed therein. The housing  200  of a refueling filtering assembly  100  will often house a plurality of filter cartridges  300  (e.g., at least two, at least four, at least six, at least eight, and/or at least ten cartridges  300 ), as in the illustrated embodiment. 
     The housing  200  includes a capsule  210 , an inlet pipe  220  extending radially thereinto, and an outlet pipe  230  extending axially therefrom. An inlet scaffold  240 , and an outlet scaffold  250  can be suspended inside the capsule  200  to support opposite ends (i.e., the inlet end and the outlet end, respectively) of the filter cartridges  300 . The inlet scaffold  240  (or other analogous structure) allow fuel introduced through the inlet pipe  220  to flow around the circumferences of the filter cartridges  300 . The outlet scaffold  250  (or other analogous structure) allows only filtered fuel exiting the cartridges  300  to flow to the outlet pipe  230 . 
     Referring now to  FIG. 3 , the filter cartridge  300  generally comprises a filter element  400  and a fuse element  500 . A filter manufacturer can fabricate the filter element  400  and the fuse element  500  as an integral cartridge, which is supplied as a unit to an end user. That being said, a filter cartridge  300  compiled from separately manufactured and/or supplied elements  400 / 500 , is possible and contemplated. 
     The filter element  400  defines an inlet chamber  401  and an outlet chamber  402 , with the inlet chamber  401  communicating with the inlet pipe  220  in the filter assembly  100 . The filter element  400  can comprise a cylindrical pack of filtering media  410  having an outer radial face  411  defining the inlet chamber  401  therearound, and an inner radial face  412  defining the outlet chamber  402  therewithin. The media  410  can be formed from, for example, one or more layers of filtration material folded into pleats and then shaped into the cylindrical pack. 
     The filter element  400  additionally comprises a first end cap  420 , a second end cap  430 , and a center sleeve  440 . The first end cap  420  comprises a circular wall  421  bonded to and sealing the adjacent axial face of the filtering media  410 , and also closing the adjacent end of the outlet chamber  402 . (The illustrated cap  420  also includes a radial rim  422  surrounding the wall  421 .) The second end cap  430  comprises an annular wall  431  bonded to a sealing the adjacent axial face of the filtering media  410 , and leaving open the adjacent end of the outlet chamber  402 . The center sleeve  440  includes a cage-like cylindrical wall  441  having a first hem  442  attached to the first end cap  420 , and a second hem  443  attached to the second end cap  430 . 
     The fuse element  500  is perhaps best explained by first referring to  FIGS. 4A-4C . The fuse element  500  can generally comprise a canister  510 , a poppet podium  520 , a poppet  540 , a corridor  550 , and an exit annex  560 . These components together define an exit chamber  501 , an exit door  502 , a fuse-monitoring chamber  503 , and fuse-monitoring channels  504 . The exit chamber  501  communicates with the outlet chamber  402  of the filter element  400 . The exit door  502  communicates with the housing&#39;s outlet pipe  230 . The fuse-monitoring chamber  503  communicates, via the channels  504 , with the inlet chamber  401  of the filter element  400  (See  FIG. 4B ). 
     The poppet  540  is movable from an open position ( FIGS. 4A and 4B ) to a closed position ( FIG. 4C ). When the filter cartridge  300  is installed, and during normal operation thereof, the poppet  540  is in its open position. When the fuse element  500  is “blown”, the poppet  540  moves to, and remains in, its closed position. 
     When the poppet part  540  is in its opened position, it separates the pre-exit chamber  501  from the monitoring chamber  503 . Filtered fluid flows from the outlet chamber  402  to the pre-exit chamber  501  and then through the exit door  502 . (See arrows in  FIG. 4A .) And not-yet filtered fluid flows from the inlet chamber  401  to, and is trapped within, the fuse chamber  503 . (See arrows in  FIG. 4B .) It may be noted for future reference that fluid pressure within the pre-exit chamber  501  will correspond to that of the outlet chamber  402  and fluid pressure within the fuse-monitoring chamber  503  will correspond to that of the inlet chamber  401 . Thus, the fluid pressure within the monitoring chamber  503  will be less than that within the pre-exit chamber  501 . (Assuming there is a pressure drop across the filtering media  410 , which almost always occurs.) 
     When the poppet part  540  is in its closed position, it seals the exit door  502 . ( FIG. 4C .) The outlet chamber  402  still communicates with the exit chamber  501 , but fluid cannot pass through the exit door  502  to the housing outlet pipe  230 . The inlet chamber  401  still communicates with the monitoring chamber  503 . The poppet part  540  no longer separates the chambers  501  and  503 , whereby they communicate with each other. But again, any fluid flowing into the exit chamber  501  is trapped therein because the poppet  540  closes the exit door  502 . It may be noted for future reference that fluid pressure inside the chamber  503  corresponds to a mix of fluid from both the inlet chamber  401  and the outlet chamber  402 , while fluid pressure outside the exit door  502  corresponds to that of the outlet chamber  402  alone. 
     Referring additionally to  FIG. 5 , the fuse element  500  is shown without its movable poppet  540 . The canister  510  comprises a cylindrical side wall  511 , a first axial wall  513 , and a second axial wall  514 , that define the confines of the exit chamber  501 . The first axial wall  513  has an array of fluid slots  515  that communicate with the exit chamber  501 , and a stem-receiving opening  516  (that does not communicate with the exit chamber  501 ). The second axial wall  514  has an inner radial edge  517  defining the exit door  502 , and an axial shoulder  518  surrounding this edge  517 . 
     The poppet podium  520  has a dome-shaped side wall  521 , tapering axially away from the canister&#39;s wall  513 , and defining the fuse-monitoring chamber  503 . The wall  521  has a central stem-receiving opening  523  on its peak that is coextensive with the canister&#39;s stem-receiving opening  516 . A rim  524  can surround the base of the side wall  521 , and a lip  525  can extend radially inward from the rim  524 . The rim  524  and/or the lip  525  define an open end of the podium  420 . 
     The corridor  550  comprises a cylindrical side wall  551  extending between the adjacent end cap  430  of the filter element  400  and the adjacent wall  513  of the canister  510 . An internal corridor wall forms a stem-receiving opening  552  that is coextensive with canister/podium openings  516 / 523 , and these openings  516 / 523 / 552  together form a passageway into the fuse-monitoring chamber  503 . Internal walls  553  form tunnels in the corridor  550  extending through the cylindrical side wall  551  and to the stem-receiving opening  552 . These tunnel-forming walls  553  define the monitoring channels  504 , and connect the inlet chamber  401  to the monitoring chamber  503  (via the openings  516 / 523 / 552 ). The space within the cylindrical side wall  551 , and not occupied by the internal walls  552 / 553 , communicates with the exit chamber  501  via the fluid slots  5165  in the canister  510 . 
     The exit annex  560  can comprise a cylindrical wall  561  extending axially away from the adjacent canister wall  514  and/or the exit door  502 . A circumferential groove  562  can be formed in the wall  561 , for receipt of a sealing member  563  (e.g., an O-ring). In the filter assembly  100 , exit annex  560  would be received in an opening in the housing scaffold  250  (See  FIG. 2A ), and the sealing member  563  would seal the interface therebetween. 
     The poppet  540 , shown alone in  FIGS. 6A and 6B , can comprise an conical head  541  having an inlet-pressure side  542 , an outlet-pressure side  543 , and radial rim  544  extending therearound. In the illustrated embodiment, the inlet-pressure side  542  is relatively flat and the outlet-pressure side  543  has a conical contour, whereby the side  543  has a greater surface area. A stem  545  can extend axially from the inlet-pressure side  542  of the head and have axial ridges  456  formed thereon. Umbrella-like webs  547  can span between the poppet&#39;s head  540  and its stem  545 . 
     Returning now to  FIGS. 4A-4B , and also  FIGS. 4D-4J , the poppet  540  is initially staged within podium  520  with its head  541  captured by the canister&#39;s lip  525 . ( FIG. 4D .) Filtered fuel from the outlet chamber  402  flows into the corridor  550 , through the canister slots  515 , and into the exit chamber  501 . ( FIG. 4E .) As the exit door  502  is open (e.g., not blocked by the poppet  540 ), fluid in the exit chamber  501  exits therethrough. ( FIG. 4A .) The poppet head  541  prevents fluid from inside the monitoring chamber  503  from entering the exit chamber  501 , whereby only filtered fluid from the outlet chamber  402  flows through the open exit door  502 . 
     The poppet&#39;s stem  545  is received within the openings  552 / 523 / 516  in the corridor  550 , the podium  520 , and the canister  510 . ( FIG. 4E .) Referring not to  FIG. 4G , the openings&#39; circular diameters are sized and shaped to closely hug the outer perimeter of the stem  545 , and its ridges  546  form tunnels  505  through the openings  552 / 523 / 515 . Unfiltered (and higher pressure) fluid from the inlet chamber  401  flows through channels  504  to the tunnels  505 . ( FIG. 4H .) Thus, inlet-pressure fluid fills the monitoring chamber  503 . ( FIG. 4B .) 
     When the poppet  540  is in its open position, inlet-pressure fluid within the monitoring chamber  503  pushes its side  542  toward the exit door  502  and outlet-pressure fluid within the exit chamber  501  pushes its side  543  in the opposite direction away from the exit door  502 . ( FIG. 4I .) The poppet  540  is additionally confined by capture of its head  541  by the podium lip  525  and the press-fit connection of its stem  545  in the openings  516 / 523 / 552 . ( FIGS. 4D and 4E .) During normal operation, the push of the inlet-pressure fluid within the monitoring chamber  503  is not sufficient to overcome the opposite outlet-pressure push, the lip capture, and/or the press-fit connection. 
     However, should the filter media  510  become clogged (for example), the inlet pressure would rise and/or the outlet pressure would drop, thereby increasing the pressure differential between the inlet chamber  401  and the outlet chamber  402 . With a rise in pressure differential, the push of the inlet-pressure fluid within the monitoring chamber  503  becomes strong enough to overcome the outlet-pressure fluid in the exit chamber  501 , to bend the podium lip  525  in a releasing direction, and to dislodge the stem  545  from its press-fit connection. 
     The poppet  540  accordingly moves from its open position to its closed position, whereas it seals the exit door  502 . ( FIG. 4C .) In this position, the poppet&#39;s side  543  is braced against the canister shoulder  518 . ( FIG. 4J .) Fluid from both the inlet chamber  401  and the outlet chamber  402  communicate with the exit chamber  501  whereby the fluid pushes against side  542  of the poppet at a pressure greater than the outlet-pressure. This fluid pressure securely holds the poppet  460  against the shoulder  518  during continued operation of the filter assembly  100  (e.g., with other non-clogged cartridges). The size/shape of the poppet head  541  prevents it from escape through the exit door  502 . 
     Significantly, the filter cartridge  300  and/or the fuse element  500  does not provide a bypass or alternate exit path upon closing of the exit door  502 . In a filter assembly  100  housing a single cartridge  300 , this would result in halt in exit flow, thereby providing an indication that the filter cartridge  300  needs to be replaced. In a filter assembly  100  housing a plurality of filter cartridges  300 , exit flow would continue from the remaining filter cartridges. 
     The poppet  540  and its staging within the podium  520  are thus designed so that the poppet  540  remains in its open position until a pressure differential between the inlet chamber  401  and the outlet chamber  402  reaches a predetermined range corresponding to clogging of the filter media  410 . The “blow” point of the fuse element  500  can be altered by adjusting the relative surface areas between inlet-pressure side  542  and the outlet-pressure side  543  of the poppet head  540 . Additionally or alternatively, the capture strength of the podium lip  525  can be modified and/or the press-fit stem connection can be changed. But, in any event, the fuse element  500  can be constructed without electrical circuits, biasing springs, complicated mechanical linkages, and/or precision instrumentation. 
     Referring now to  FIG. 5 , in the illustrated embodiment, the center sleeve  440 , the second end cap  430 , the corridor  550 , the canister&#39;s axial wall  513 , and the poppet podium  520  can be formed in one piece. For example, they can be molded from a polymeric material. To assembly the filter cartridge  300 , the filter media  410  would be inserted around the sleeve  440  and the non-integral end cap  420  bonded thereto to seal the filter element  400 . The poppet  540  (separately molded from a polymeric material), would then inserted into the podium  520 , its stem  545  press-fit into the openings  516 / 523 / 552 , and the lip  525  bent around its head  541 . After installation of the poppet  540 , the rest of the canister  510  (e.g., its walls  511  and  514 ) would be attached to the wall  513  to close the exit chamber  501 . The exit annex  560  can be formed in one piece with the canister walls  511 / 514 , or formed separately and attached thereto. 
     Although the filter assembly  100 , the cartridge  300 , the filter element  400 , and/the fuse element  500  has been shown and described with respect to a certain embodiments, equivalent alterations and modifications should occur to others skilled in the art upon review of this specification and drawings. If an element (e.g., component, assembly, system, device, composition, method, process, step, means, etc.), has been described as performing a particular function or functions, this element corresponds to any functional equivalent (i.e., any element performing the same or equivalent function) thereof, regardless of whether it is structurally equivalent thereto. And while a particular feature may have been described with respect to less than all of embodiments, such feature can be combined with one or more other features of the other embodiments.