Abstract:
A fuel filter cartridge assembly employs a two piece housing to house a disposable, incineratable filter unit. The filter unit is constructed to cooperate with the sealing mechanism of the housing to seal the assembled cartridge against a fuel inlet/outlet conduit. Tabs formed on the filter unit end cap cooperate with slots formed in the housing to ensure that only compatible filter units are used.

Description:
REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. provisional application No. 60/182,857, filed on Feb. 16, 2000. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates generally to devices for filtering and separating fluids. More particularly, the present invention relates to fuel filters having a replaceable cartridge for removing foreign particles and separating water from the fuel supply system of an internal combustion engine. 
     2. Description of the Related Art 
     Diesel fuel supplies frequently contain significant quantities of abrasive particles and water which present the potential for permanent damage to the components of the fuel injection pump, the fuel delivery system and the engine. Consequently, an effective fuel filter as a practical necessity is conventionally incorporated into the fuel supply system of a diesel engine. A multitude of conventional fuel filters employ a disposable filter cartridge which is replaced at pre-established intervals of filter usage. Such fuel filters perform the dual function of removing particulate material from the diesel fuel and separating water from the fuel. 
     U.S. Pat. No. 4,976,852 and U.S. Pat. No. 5,084,170, which are assigned to the assignee of the present invention, disclose fuel filter assemblies to which the present invention relates. The fuel filters employ a base which mounts a disposable filter cartridge. In some disclosed embodiments, the cartridge includes a single stage filter system wherein fuel flows axially and radially to a filter element for removing particulate matter. The filter element also functions as a water barrier. Filtered fuel flows axially and exits through an outlet passage of the base. Water may be collected in a sump and periodically removed. The cartridge is secured to the base by a collar that engages a peripheral roll seam of the cartridge. 
     Most conventional fuel filter cartridges are permanently sealed metal canisters that contain a filter element and include grommets to seal the cartridge to the fuel inlet and outlet passages or ports. With use, the filter elements of such assemblies become clogged resulting in restricted fuel flow. The ability of the filter element to separate water also degrades over time. Accordingly, such cartridges must be replaced regularly to ensure the internal combustion engine is being supplied with an adequate flow of clean fuel. 
     Fuel filters have typically been constructed in the form of a metal can, permanently enclosing the filter element in a single use assembly. While these assemblies have proved to be effective and reliable, they are less than ideal in terms of waste of materials and disposal cost. Increased awareness of environmental protection and recycling of materials have led to a need for more efficient filtration systems having a minimum disposable component. In addition, environmental protection agencies seeking to reduce the volume of waste items associated with the automotive and trucking industries no longer allow used fuel filters into the normal waste stream, necessitating specialized and consequently more expensive disposal. 
     SUMMARY OF THE INVENTION 
     Briefly stated, the invention in a preferred form is a fuel filter cartridge assembly which includes a two-part housing containing a single use, incineratable filter unit. The housing is constructed of first and second cooperative sections, detachably connected to allow replacement of the used filter unit. The filter unit is constructed of a continuous, fan shaped, pleated filter element, typically composed of a form of paper. Axially spaced first and second end caps, constructed of incineratable plastic, provide support structure for the filter element and also provide a platform for the attachment of grommets which seal the unit to the fuel inlet/outlet conduit. 
     The can-shaped housing first section defines a central axial opening for receiving a typically coaxial fuel inlet/outlet conduit projecting from a cartridge-receiving base module. A sealing grommet is affixed to the inner edge of the opening for fluidly sealing the housing to the received conduit. The interior surface of the housing first section preferably incorporates at least one groove which is cooperative with tabs formed on the first end cap of the filter unit. The cooperative groove and tab structures function as a key system to prevent the use of incompatible filter elements in a particular housing. 
     The filter unit interacts with the housing grommet in a novel manner. The housing grommet has a quasi-tubular structure that extends into the housing a short axial distance and terminates at a second end. In a preferred embodiment, the housing grommet second end has at least one radially extending protrusion which functions as a locator and a retainer ring to ensure proper axial positioning and sealing of the filter unit within the housing. 
     The housing grommet is configured to cooperate with a complementary structure located in the filter element first end cap. The central opening in the first end cap is defined by an inwardly projecting shoulder having an interior diameter less that the external diameter of the grommet protrusion. The shoulder is located axially so that when the filter element is installed within the housing, this shoulder rides over the protrusion and exerts a radially inward force on an axially intermediate area of the sealing grommet, forcing the grommet into sealing contact with the exterior surface of the fuel conduit. 
     An ecological fuel filter element according to the present invention provides a filter element which lessens the potential impact of fuel filter replacement on the environment by removing fuel and solid waste from the waste stream. A filter element constructed according to the claimed invention will contain no metal and will be composed of incineratable materials. 
     The claimed invention removes the filter cartridge housing from the waste stream by making it possible to open the housing and replace only the used filter element. Fuel inside the housing can be collected and re-cycled immediately. The filter element and its trapped particulates can then be destroyed efficiently by incineration. Using this technique will ease compliance with increasingly strict environmental protection requirements while greatly reducing disposal costs. 
     An object of the invention is to provide a new and improved fuel filter cartridge and element which enable the cost effective disposal of the spent element in an efficient, environmentally friendly process. 
     Another object of the invention is to provide a new and improved fuel filter cartridge assembly of efficient and low cost construction which reduces waste and controls the release of fuel contaminants into the environment. 
     A further object of the invention is to provide a new and improved disposable fuel filter element which can be efficiently installed and replaced and functions to enhance the sealing integrity of the filter assembly. 
     A yet further object of the invention is to provide a new and improved fuel filter element which can be disposed of in a cost-effective manner which is compliant with strict environmental regulations. 
     Other objects and advantages of the invention will become apparent from the drawings and the specification. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cross sectional view of an ecological fuel filter cartridge assembly in accordance with the present invention; 
     FIG. 1A is an expanded cross sectional view of the ecological fuel filter cartridge assembly of FIG. 1 (partially illustrated); 
     FIG. 2 is a cross sectional view of the ecological fuel filter cartridge assembly of FIG. 1 mounted to a base module; 
     FIG. 3 is a cross sectional view of an ecological fuel filter cartridge assembly utilizing an alternative embodiment of a filter unit in accordance with the present invention mounted to a base module; 
     FIG. 4 is a bottom plan view of an ecological fuel filter cartridge assembly housing first section in accordance with the present invention; 
     FIG. 5 is a cross sectional view of the ecological fuel filter cartridge assembly housing first section of FIG. 4 taken along the line  5 — 5  thereof; 
     FIG. 6 is a top plan view of a filter unit end cap in accordance with the present invention; 
     FIG. 7 is a cross sectional view of the filter unit end cap of FIG. 6 taken along the line  7 — 7  thereof; 
     FIG. 8 is a bottom plan view of the filter unit end cap of FIG. 6; 
     FIG. 9 is a side elevational view of the housing first section of FIGS. 4 and 5; and 
     FIG. 10 is a cross sectional view through a fuel filter cartridge assembly housing with the filet unit removed for clarity. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to the drawings, wherein like numerals represent like parts throughout the figures, a fuel filter cartridge assembly in accordance with the present invention is generally designated by the numeral  10 . The fuel filter cartridge assembly  10  includes a cylindrical housing having a first end  12  threadably engaged with and sealed to a second end  14 . The housing surrounds and retains a filter element  30 . The housing second section  14  may preferably be equipped with a drain cock  18 . 
     Details of the configuration of the housing first section  12  are illustrated in FIGS. 4,  5 ,  9  and  10 . The housing first section includes a first end  13  that defines a central opening  16  for receiving a conduit. An axially spaced second end  15  includes threads  26  for engagement of the housing second section  14 . Complementary threads  26 ′,  26  project from the housing first and second sections, respectively. With reference to FIGS. 9 and 10, each housing section  12 ,  14  includes a retainer bump  25 ,  25 ′ located so that the housing sections must deform to permit one bump to ride over the other as the housing sections rotate relative to each other. The housing first section  12  includes a stop  21  arranged to define the fully engaged position of the threaded connection. Retaining bump  25  rides over retaining bump  25 ′ and then encounters the stop  21 . In practice, this arrangement results in a positive “snap” indicating a fully engaged position. The housing unit sections are retained in a fixed relationship relative to each other until the retaining bumps are disengaged. 
     The interior surface of the housing first section  12  defines slots  24  configured to receive complementary tabs  38  formed on the filter unit  30 . Only a filter unit  30  having correctly configured tabs  38  will be received in the housing first section  12  ensuring that the proper filter unit is used for a given application. 
     A housing grommet  20  is located in the housing first section  12  central opening  16 . The unique configuration of the housing grommet  20  serves two functions: first, the housing grommet  20  interacts with the filter unit  30  first end cap  34  to axially retain and seal the filter unit  30  within the housing first section  12 ; and second, the housing grommet  20  seals the cartridge assembly  10  to a received fuel inlet/outlet conduit projecting into the housing from the base module  60 . The housing grommet  20  has a quasi-tubular configuration which extends axially within the housing and includes at least one radially extending protrusion  22  at its axially spaced second end. The first end of the tubular housing grommet  20  is engaged with the interior rim of the central opening  16  in the first end  13  of the housing first section  12 . 
     The second section  14  of the housing includes threads  26  for engagement of the housing first section  12 . A seal  28  is preferably placed between housing first section  12  and housing second section  14  to improve the fluid sealing qualities of the threaded joint between the two housing sections. The housing second section  14  also includes a roll seam structure  27  which will be engaged by a collar  62  to retain the cartridge assembly  10  in mated position with a base module  60 . The housing second section  14  is preferably equipped with a drain cock  18  which is typically used for draining water separated from the fuel by the filter element  32 . In the ecological fuel filter cartridge assembly  10 , the drain cock  18  will also serve the function of draining fuel from the housing in preparation for separation of the housing sections  12 ,  14 . 
     The filter unit  30  includes a generally continuous filter element  32 , a first end cap  34  and a second end cap  36 . The filter element  32  is a fan-folded paper element in the form of a cylinder which typically filters particulates and separates water from the fuel. The end caps  34 ,  36  enclose the axially spaced ends of the filter element and provide structure to the paper element. The end caps  34 ,  36  have a configuration which seals to and mounts within the cartridge housing. 
     Details of the configuration of the filter unit  30  first end cap  34  are best understood with reference to FIGS. 6-8. The first end cap  34  includes a radially inwardly extending shoulder  40  defining a central opening  42  configured for receiving the axially extending tubular portion of the housing grommet  20 . The outer circumference of the first end cap  34  includes radially extending tabs  38  configured to engage the slots  24  defined by interior surface of the housing first section  12 . The arrangement of the tabs  38  and the slots  24  assures that only compatible filter units will mate with a given housing, ensuring a properly configured cartridge assembly  10  and an ecologically compliant replacement filter unit. 
     The shoulder  40  projects radially inward at an acute angle to a central axis A passing through the filter unit  30  forming an angled conical surface  41 . The shoulder projects at an angle β, which is preferably approximately 45° relative to the central axis A. 
     The filter unit  30  second end cap  36  encloses the axially spaced end of the filter element  32  in a manner similar to the first end cap  34 . In a typical embodiment of a filter unit  30 , for use in a filter assembly having a standard fuel flow path, the filter unit  30  second end cap  36  includes a tubular axial projection  44  (see FIG. 1) extending toward the first end cap  34 . The tubular extension  44  terminates in a structure configured to engage and retain a sealing grommet  50 . 
     To better understand the functional relationships between the structures of the filter unit  30  and the housing sections  12  and  14 , reference is now made to FIG.  1 A. The tabs  38  are aligned with the axially extending slots  24  defined by the interior surface of the housing first section  12 . The filter unit  30  is inserted toward the first end  13  of the housing first section  12 . As the filter unit  30  approaches the first end  13  of the housing first section  12 , the radially inward projecting shoulder  40  of the filter unit  30  first end cap  34  engages the axially extending tubular portion of the housing grommet  20 . The angled conical surface  41  formed by the angular projection of the shoulder  40  aids in allowing the shoulder  40  to ride over the radially extending protrusions  22  of the grommet  20 . 
     When the filter unit  30  has been fully received in the housing first section  12 , the radially extending shoulder  40  is axially positioned to engage an intermediate portion of the housing grommet  20 , exerting a radially inward force on that intermediate portion. The filter unit  30  is thus captured and retained by the first section  12  in a generally fixed axial position relative to the housing first section. The housing second section  14  is then threadably engaged with the housing first section  12  forming a sealed cylindrical enclosure around the filter unit  30 . 
     The ecological fuel filter cartridge assembly  10  may now be installed on a filter base module  60  as illustrated in FIG.  2 . The filter base module  60  forms a receptacle for receiving the fuel filter cartridge assembly  10 . A co-axial fuel inlet/outlet conduit projects from the filter base module  60  into the fuel filter cartridge assembly  10  through the central opening  16  in the housing first section  12 . The fuel inlet/outlet conduit includes an inlet conduit  66  surrounded by a co-axial outlet conduit  68 . In a preferred configuration, the inlet conduit has a greater axial length than the outlet conduit  68 . A threaded collar  62  passes over the fuel filter cartridge assembly  10  and engages the molded peripheral lip  27  extending from the housing second section  14 . The collar  62  threadably engages complementary threads on the filter base module  60 , retaining the fuel filter cartridge assembly  10  in a stable mated position with the filter base module  60 . The base module  60  and collar  62  prevent the housing sections  12 ,  14  from deforming and make it impossible for the two housing sections  12 ,  14  to disengage from each other. A gasket or  0 -ring  28  is positioned between the two housing sections. 
     FIG. 2 illustrates a base module  60  and associated fuel filter cartridge assembly  10  utilizing a standard flow of fuel through the filter element  32 . In this configuration the greater axial length of the fuel inlet conduit  66  provides an end location which is engaged by a grommet  50  retained on the tubular axial projection  44  of the filter unit second end cap  36 . The sealed engagement between the fuel inlet conduit  66  and the tubular axial projection  44  forms a fuel inlet path directing fuel axially into the housing second section where it flows radially and axially to the filter element  32  in the general direction of the FIG. 2 arrows. Passing radially through the filter element  32 , the filtered fuel then flows generally axially into the fuel outlet conduit  68 . 
     A reverse fuel flow path can be achieved utilizing an alternative embodiment of the filter unit as illustrated in FIG.  3 . The reverse flow path is generally illustrated by the FIG. 3 arrows. A reverse flow filter unit  30 ′ utilizes a second end cap  37  having no tubular projection or central opening. Instead, filter unit  30 ′ first end cap  35  incorporates a tubular axial projection  45  and sealing grommet  51 which extends toward filter unit  30 ′ second end cap  37 . The tubular projection  45  and sealing grommet  51  engage the inner axially extended fuel conduit  69 , which in this embodiment serves as the fuel outlet conduit. Fuel enters the cartridge assembly  10  via the outer, shorter fuel inlet conduit  67  where it flows radially and axially to the filter element  32 . The fuel passes radially through the filter element  32  and then flows generally axially to the fuel outlet conduit  69 . Thus, a reverse flow can be accomplished with the same filter base module  60  and housing  12 ,  14  by utilization of the filter unit  30 ′. 
     In either the embodiment illustrated in FIG. 2, or the embodiment illustrated in FIG. 3, the sealing grommet  50 ,  51  serves to separate filtered (clean) from unfiltered (dirty) fuel by engaging both the filter unit and the axially extending fuel conduit. Similarly, in either configuration an intermediate portion of the housing grommet  20  is engaged by the radially inward extending shoulder  40  of the filter unit first end cap  34 ,  35 . The shoulder  40  exerts a radially inward force on the intermediate portion of the grommet  20  urging it into sealing engagement with the exterior surface of the fuel inlet/outlet conduit. The retaining collar  62  connects the fuel filter cartridge assembly  10  to the filter base module  60  and urges the housing grommet  20  into axial contact with the filter base module, further enhancing sealing between the fuel filter cartridge assembly  10  and the filter base module  60 . 
     In either configuration, the fuel filter cartridge assembly  10  may be removed from the filter base module  60  by removing the threaded collar  62 . Prior to removal, the drain cock  18  may be utilized to drain fuel from the fuel filter cartridge assembly  10  to avoid the spillage of fuel. Once removed from the filter base module, the fuel filter housing sections  12 ,  14  may be separated and the filter unit  30 ,  30 ′ removed and replaced with a new filter unit  30 ,  30 ′. The housing sections  12 ,  14  are then reassembled into a sealed unit which is then reinstalled in the filter base module  60 . A filter unit  30 ,  30 ′ in accordance with the present invention contains no metal and is constructed of incineratable materials. The spent filter unit may be efficiently disposed of via incineration, reducing the waste stream. All fuel is either drained and recycled or combusted with the used filter unit  30 ,  30 ′. 
     Preferred filter element materials are paper and paper products containing synthetic fibers. A preferred material for the end caps is cross-linked polyethylene. The polyethylene may be a high density polyethylene, such as HDPE. Such polyethylene plastics provide a desirable combination of corrosion resistance and strength. Other plastics common to automotive uses may also be appropriate, such as nylon or glass filled nylon. An incineratable adhesive, such as Plastisol™, is used to join the filter element to the end caps to form the filter unit,  30 ,  30 ′. The resulting filter unit does not add any materials to the waste stream that are not already present. The filter unit components will burn with a relatively high energy value (BTU/Pound) that may be recovered for power generation or other useful purpose. 
     Thus, the ecological fuel filter cartridge assembly  10  and filter unit  30  allow the frequent replacement of fuel filters while greatly reducing the risk of fuel entering the environment via used filter cartridges and significantly reducing the volume of waste and cost of disposal typically associated with such replacement. 
     While preferred embodiments of the foregoing invention have been set forth for purposes of illustration, the foregoing descriptions should not be deemed a limitation of the invention herein. Accordingly, various modifications, adaptations and alternatives may occur to one skilled in the art without departing from the spirit and the scope of the present invention.