Abstract:
A filter cartridge that is designed to accommodate differences in lengths between an outer filter media and an inner filter media by providing a flexible connection between the inner filter media and the outer filter media. In addition, the endplates of the inner filter and the outer filter together define a gasket groove that receives a gasket. Using the endplates of the inner and outer filter media to define the gasket groove eliminates a mold parting line that can lead to fluid leakage.

Description:
FIELD 
     This disclosure generally pertains to the field of filtration, and more particularly to a filter cartridge. 
     BACKGROUND 
     The use of filter cartridges to filter fluids such as air, fuel, oil and other fluids is well known. A filter cartridge can include, among other features, one or more filter media and plates secured to the filter media at opposite ends. In the case of a filter cartridge configured as a filter-in-filter construction, the inner and outer filter media can have different lengths. The different lengths can create difficulties during assembly of the filter cartridge. 
     In addition, in certain filter cartridge constructions, a gasket groove is formed in a bottom endplate that receives a gasket for sealing with a standpipe around which the filter cartridge is disposed when the cartridge is installed in a filter housing. During molding of the gasket groove, one or more parting lines are formed on the groove by the mold components that are used to form the bottom endplate. The parting line(s) creates a risk of fluid leakage between the gasket and the endplate. 
     SUMMARY 
     A filter cartridge is described that is designed to accommodate differences in length between an outer filter media and an inner filter media by providing a flexible connection between the inner filter media and the outer filter media. 
     In addition, a filter cartridge is described that includes an inner filter and an outer filter, where endplates of the inner filter and the outer filter together define a gasket groove that receives a gasket. Using the endplates of the inner and outer filter to define the gasket groove eliminates a parting line that can lead to fluid leakage. 
     In one embodiment, a filter cartridge is provided that comprises an outer filter having a central axis and that includes first filter media and an endplate attached to an end of the first filter media. The endplate includes an outer portion that includes a segment attached to the first filter media, an inner portion substantially surrounded by the outer portion and flexibly connected to the outer portion so that the inner portion and the outer portion are flexible relative to one another to permit relative movements therebetween, a central opening, and at least one opening in the endplate between the outer portion and the inner portion. The cartridge also includes an inner filter that includes second filter media with an end connected to the inner portion. In addition, the inner filter is sized to at least partially fit within the outer filter, and the inner filter includes a central axis coaxial to the central axis of the outer filter. 
     In another embodiment, a filter cartridge is provided comprising an outer filter having a central axis and that includes first filter media and an endplate attached to an end of the first filter media. The cartridge also includes an inner filter that includes second filter media and an endplate attached to an end of the second filter media. The inner filter at least partially fits within the outer filter, and the inner filter includes a central axis coaxial to the central axis of the outer filter. The endplate of the outer filter and the endplate of the inner filter define a gasket groove, and a gasket is disposed in the gasket groove. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional view of a filter cartridge according to one embodiment installed in a filter housing. 
         FIG. 2  is a perspective view of the filter cartridge removed from the filter housing. 
         FIG. 3  is a cross-sectional view of the filter cartridge. 
         FIG. 4  is a perspective view of the filter cartridge of  FIG. 2  in a partially assembled state. 
         FIG. 5  is a perspective view of the filter cartridge in a more completely assembled state. 
     
    
    
     DETAILED DESCRIPTION 
     With reference to  FIGS. 1-3 , a filter cartridge  10  according to one embodiment is illustrated. As illustrated, the filter cartridge  10  is designed to be installed in a filter housing  100  for filtering a liquid, for example diesel fuel, and removing water from the liquid. This description will hereinafter describe the liquid as fuel. However, it is to be realized that the concepts described herein can be used for other liquids. In addition, in appropriate circumstances, the concepts described herein can be used to remove contaminants other than water from the liquid. And, in appropriate circumstances, the concepts described herein can be used on filter cartridges that filter other types of fluids, for example air, oil and other fluids. 
     The filter cartridge  10  is of filter-in-filter construction including an outer filter  12  and an inner filter  14  disposed concentrically inside of the outer filter. The cartridge  10  is designed for outside-in flow, with fuel entering the cartridge from the outside and flows inwardly to the inside of the cartridge. 
     The outer filter  12  includes a first generally circular filter media  16  disposed around a central axis A-A, an upper endplate  18  attached to an upper end of the media  16 , and a bottom endplate  20  attached to a bottom end of the media  16 . The inner filter  14  includes a second generally circular filter media  22  disposed around the central axis A-A. An upper end of the media  22  is attached to the upper endplate  18 , and a bottom endplate  24  is attached to the bottom end of the media  22  and is attached to the bottom endplate  20 . 
     As shown in  FIGS. 2-5 , the bottom endplate  20  includes an outer portion  30  that is generally ring-shaped with a first radially-inward facing rim  32 . The outer portion  30  that is attached to the media  16  is substantially flat and horizontal. The endplate  20  also includes an inner portion  34  that is substantially surrounded by the outer portion  30 . The inner portion  34  is generally ring-shaped and includes a radially-outward facing rim  36  that generally faces the first radially-inward facing rim  32 , and a second radially-inward facing rim  38  that defines a central opening  40 . 
     The inner portion  34  is flexibly connected to the outer portion  30  so that the inner portion and the outer portion are flexible relative to one another to permit relative movement therebetween. For example, a plurality of resilient arms  42  are connected between the first radially-inward facing rim  32  and the radially-outward facing rim  36 . The arms  42  permit relative movements both axially and radially between the inner portion  34  and the outer portion  30 . Each arm  42  includes a first end  44  attached to the first radially-inward facing rim  32  and a second end  46  attached to the radially-outward facing rim  36 . The first end  44  is attached to the first radially-inward facing rim at a location that is circumferentially offset from the location of attachment of the second end  46  of the respective arm to the radially-outward facing rim, thereby creating a circumferential link  48  between the ends  44 ,  46 . The space between the arms  42  create water drainage openings  50  between the inner portion  34  and the outer portion  30  to allow water that is separated from the fuel to drain from the filter cartridge  10  into a water collection area  102  of the filter housing  100 . 
     The inner portion  34  also includes an axially extending, generally circular flange  52  that generally extends upwardly from the radially-outward facing rim  36 . The flange  52  is spaced from the second radially-inward facing rim  38  to form a ledge  53 . In addition, the inner surface of the flange  52  includes a circumferential ridge  54  to connect with the bottom endplate  24 . 
     At the outer peripheral edge of the outer portion  30 , a lip  55  extends downwardly therefrom at an angle. In the illustrated embodiment, the lip  55  is generally circular and is integrally formed with the outer portion  30 , although the lip could be non-integrally formed. When the filter cartridge  10  is installed, the lip  55  seals with the interior surface of the housing  100  as shown in  FIG. 1 . Instead of the lip  55 , or in addition to the lip  55  if found to be acceptable, a gasket, for example an o-ring or a molded gasket, can be provided for sealing with the interior of the housing  100 . 
     The endplate  24  includes a generally horizontal and substantially flat portion  56  that is attached to the media  22 . A central opening  58  is formed in the endplate  24  through which a standpipe  104  of the filter housing  100  extends when the cartridge is installed. The inner rim of the opening  58  is generally aligned with the rim  38 . The openings  40  and  58  are illustrated as being generally circular in shape for fitting around a generally circular standpipe. However, the openings  40 ,  58  could have other shapes as well, for example oval, to fit around, for example, an oval standpipe. 
     In addition, the endplate  24  includes a segment  60  in the form of an axially extending, generally circular flange. The flange  60  includes a circumferential recess  62  formed on the outer surface thereof that, together with the ridge  54 , forms a snap fit connection to connect the flange  60  to the flange  52 . As illustrated in  FIG. 2 , the flange  60  extends downwardly from the portion  56  at a location spaced from the perimeter of the opening  58 . Therefore, a ledge  64  is created between the flange  60  and the perimeter of the opening  58 . When the flange  60  is connected to the flange  52 , the ledges  53  and  64  and the flange  60  define a gasket groove  64  that receives a gasket  66  that seals with the standpipe  104  of the filter housing  100 , as shown in  FIG. 1 , to prevent fluid leakage between the filter cartridge  10  and the standpipe. If desired, the flange  52  can fit inside the flange  60  so that the ledges  53 ,  64  and the flange  52  define the gasket groove. 
     In use of the cartridge  10 , the cartridge is installed into the filter housing  100  around the standpipe  104 . Fuel can include water therein in different forms, including free water, e.g. droplets, and emulsified water. Preferably, the filter media  16  is designed so that free water is initially filtered when fuel enters the filter from the outside. The free water does not penetrate the media  16  and remains substantially outside the filter. The media  16  also coalesces the majority of the emulsified water and separates the now coalesced water from the fuel. Water, being heavier than fuel, settles down to the bottom of the filter cartridge  10 , and drains through the openings  50  in the bottom endplate  20  to the water collection area  102 . By the time the fuel interfaces with the media  22 , most of the water has been separated, and the media  22  performs a final filtration of the fuel before the fuel enters the center of the filter cartridge. The filtered fuel then enters the standpipe  104  through openings  106  therein and flows to an outlet in known manner, leading to a downstream protected component, for example a fuel pump. 
     The invention may be embodied in other forms without departing from the spirit or novel characteristics thereof. The embodiments disclosed in this application are to be considered in all respects as illustrative and not limitative. The scope of the invention is indicated by the appended claims rather than by the foregoing description; and all changes which come within the meaning and range of equivalency of the claims are intended to be embraced therein.