Abstract:
A fluid filter arrangement is provided. The fluid filter arrangement includes a filter cartridge having a ring of filter media sealingly bonded to first and second end caps. The first and second end caps having first and second openings, respectively, fluidly communicating with the interior of the ring of filter media. The second end cap includes a seal surrounding the second opening. The fluid filter arrangement further includes an adaptor having at least one housing mount on the external side and an annular flange having a valve seat on the internal side. The adaptor is sealingly mates with the second the end cap.

Description:
FIELD OF THE INVENTION  
       [0001]     This invention generally relates to fluid filter arrangements, more particularly, to fluid filter arrangements that include a fluid bypass which allows fluid to bypass the filter media under excessive pressure conditions.  
       BACKGROUND OF THE INVENTION  
       [0002]     Fluid filters incorporating fluid bypasses are well known in the art. Typically, the bypass incorporates a pressure relief valve that acts to allow dirty fluid to short-circuit the filter media of the filter under high pressure events. For example, short-circuiting is permitted when the filter media becomes sufficiently clogged with contaminants that have been filtered from the fluid. Such contaminant restriction will lead to an insufficient amount of fluid flowing through the filter. Although it is not typically preferred to allow unfiltered fluid to flow through the filter without being filtered, it is more preferable to allow a sufficient amount of lubrication fluid (or other fluid) to flow through the system to ensure proper lubrication of moving components. Otherwise, restricting the amount of lubrication fluid to an insufficient amount can result in catastrophic engine failures.  
         [0003]     One example of such a fluid filter arrangement with a fluid bypass is disclosed in U.S. Pat. No. 5,770,054 to Wilhelm Ardes. The &#39;054 patent to Ardes includes a filter element with an upper plastic end cap providing a bypass valve seat that seats against a valve on a standpipe in a housing. The filter element also includes a lower plastic end cap that carries a felt gasket. There are various drawbacks associated with Ardes, including significantly that different end cap structures are required for the upper and lower end caps. Also Ardes requires precise alignment between end caps is required to position the valve seat of the upper end cap, considering a plastic valve seat is utilized. The present invention relates to improvements over Ardes and the current state of the art in fluid filters that incorporate a fluid bypass.  
       BRIEF SUMMARY OF THE INVENTION  
       [0004]     According to an aspect of the present invention, a fluid filter arrangement includes an adaptor for adapting a housing (such as the housing disclosed in Ardes) to provide for a fluid bypass through the housing components, and a more simplified filter cartridge (a.k.a. filter element) for use therewith. The filter cartridge includes a tubular ring of filter media having opposing first and second ends sealingly bonded to first and second end caps, respectively. The first and second end caps define first and second openings, respectively. The second end cap forms a seal that surrounds the second opening. The fluid filter arrangement further includes an adaptor having external and internal sides and defining a bypass port therethrough. The adaptor has at least one housing mount on the external side for mounting the adaptor to the housing; and an annular flange having a valve seat on the internal side. The adaptor does not carry a valve, but can be used in connection with a housing that provides a standpipe with a valve. The adaptor mates with the second end cap and engages the seal.  
         [0005]     A further feature of one embodiment of the present invention is the provision for multi-component end caps which are potted to the filter media and integrally provide a seal. The same end cap components may be used for both upper and lower end caps, which at the same time providing seals at both locations.  
         [0006]     According to another claimed aspect, a fluid filter arrangement includes an adaptor for adapting a housing to provide for a fluid bypass through the housing components, and a more simplified filter cartridge for use therewith. The filter cartridge includes a tubular ring of filter media having opposing first and second ends sealingly bonded to first and second end caps, respectively. The first and second end caps define first and second openings, respectively. The adaptor has external and internal sides and defines a bypass port therethrough. The adaptor has at least one housing mount on the external side for mounting to the housing and an annular flange having a valve seat on the internal side. The adaptor does not carry a valve and is sealingly received into the second opening of the second end cap. The adaptor has an outer periphery sized smaller than an outer periphery of the second end cap.  
         [0007]     It is a feature of the present invention that the a combination of a housing adapter and filter element can provide potential advantages such as replacing fewer parts at each filter change, thereby reducing waste and costs. The present invention also provides the opportunity for a more simplified filter element, again lowering material and capital costs, especially in the instance where the same components are used for both the upper and lower end caps. An additional advantage is improved serviceability. For example, it is a feature of an embodiment that the installation and removal means for attaching the filter element to the housing lid can be changed from a difficult snap fit to a relatively easy push and slide radial fit onto the housing adapter. This can significantly ease filter change out and reduce contact with filtered fluids, such as used lubrication oil.  
         [0008]     Other aspects, objectives and advantages of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]     The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the present invention and, together with the description, serve to explain the principles of the invention. In the drawings:  
         [0010]      FIG. 1  is a cross-sectional view of an exemplary embodiment of a fluid filter arrangement constructed in accordance with the teachings of the present invention;  
         [0011]      FIG. 2  is an enlarged partial cross-sectional view of the housing adaptor and the filter cartridge of  FIG. 1  wherein the second end cap sealingly receives the housing adaptor;  
         [0012]      FIG. 3  is a perspective view of the housing adaptor in  FIG. 2 ;  
         [0013]      FIG. 4  is a partial cross-sectional view of a filter cartridge in combination with another embodiment of an adaptor in accordance with the teachings of the present invention;  
         [0014]      FIG. 5  is a perspective view of the adaptor of  FIG. 4 ;  
         [0015]      FIG. 6  is a partial cross-sectional view of a filter cartridge in combination with a further embodiment of an housing adaptor in accordance with the teachings of the present invention;  
         [0016]      FIG. 7  is a partial cross-sectional view of a filter cartridge in combination with a further embodiment of an adaptor in accordance with the teachings of the present invention; and  
         [0017]      FIG. 8  is a partial cross-sectional view of a filter cartridge in combination with a further embodiment of an housing adaptor in accordance with the teachings of the present invention. 
     
    
       [0018]     While the invention will be described in connection with certain preferred embodiments, there is no intent to limit it to those embodiments. On the contrary, the intent is to cover all alternatives, modifications and equivalents as included within the spirit and scope of the invention as defined by the appended claims.  
       DETAILED DESCRIPTION OF THE INVENTION  
       [0019]     A fluid filter arrangement  10  in accordance with the present invention is illustrated in  FIG. 1 . The fluid filter arrangement  10  includes a housing  12  in the form of a canister with a housing lid  14 , a housing adaptor  15 , and a bypass valve  16 . The filter arrangement  10  also includes a filter cartridge  18  for use with the housing components. The housing lid  14  threadedly connects to the housing  12  to provide an interior cavity  20 . The stand pipe  22  extends vertically upwards from the housing  12  into the interior cavity  20 . The stand pipe  22  includes the bypass valve  16  therein. The filter cartridge  18  is releasably attached to the housing lid  14  by the housing adaptor  15  and located within the interior cavity  20 . In an assembled condition, the filter cartridge  18  is installed between the housing lid  14  and the housing  12  and surrounds the stand pipe  22 .  
         [0020]     The housing  12  includes an inlet  26  and an outlet  28  to the cavity  20 . When the fluid filter arrangement  10  is assembled, the filter cartridge  18  is inserted into the cavity  20 , the inlet  26  is in fluid communication with the exterior of the filter cartridge  18  and the outlet  28  is in fluid communication with the interior of the cartridge  18 . Specifically, the outlet  28  is in fluid communication with the interior of the cartridge  18  through a plurality of ports  32  in the stand pipe  22  which, after assembly, are positioned within the interior of the filter cartridge  18 .  
         [0021]     The filter cartridge  18  includes a ring of filter media  36  with opposed ends. The filter media  36  provides an interior volume which can be occupied in part with a tubular support (not shown) if desired to support the ring of filter media or left empty. In any event, the interior volume of the filter media  36  provides sufficient clearance to receive the standpipe  22 . Bottom and top end caps  38 ,  40  are sealingly bonded to first and second ends  42 ,  44  of the filter media  36 , respectively. The end caps  38 ,  40  may be formed of plastic or can be a combination of materials such as plastic and rubber material. The end caps  38 ,  40  are sealingly bonded to the ring of filter media  36  by a potting material  46  such as plastisol. Specifically, opposed ends of the ring of filter media  36  are received in annular wells  47  provided by a bottom and inner and outer axially extending walls of the end caps  38 ,  40 . Other alternative seal bonding techniques may be used and include plastic welding techniques or other such bonding means so as to prevent short circuiting of fluid between the filter media and the end cap.  
         [0022]     In an embodiment, the end caps are comprised of two components assembled together. For example, the bottom end cap  38  includes an L-shaped end plate  48  and an annular gasket  50 , which are assembled together. It should be noted that the present invention will be described with reference to end plates having an L-shape. However, it is contemplated that substantially flat end plates could also be used in accordance with the teachings of the present invention. The gasket  50  is sealingly received into a central hole in the end plate  48  with an interference fit therebetween. The gasket  50  surrounds and provides an opening  49  of the bottom end cap  38 . The gasket  50  is adapted to create a seal between the bottom end cap  38  and the housing  12  when the filter cartridge  18  is installed over the standpipe  22 . Particularly, the gasket  50  provides a radial seal between the outer surface  52  of a base portion  54  of the housing  12  from which the standpipe  22  extends and through which the outlet  28  is provided and the L-shaped end plate  48 . The standpipe  22  extends into the interior of the filter cartridge  18  via the first opening  49  provided by the gasket  50 .  
         [0023]     The L-shaped end plate  48  is preferably made from a substantially rigid material and more preferably from a plastic, but may also comprise metal or an alternative incinerable material. It will be appreciated that the gasket  50  prevents fluid from short-circuiting the filter cartridge  18  and preferably is an elastomeric material (which is meant to include natural and/or synthetic rubber and/or other elastomeric materials that are resiliently rubber-like or resiliently flexible). The end plate  48  and the gasket  50  are assembled together prior to potting the end caps to the filter media with plastisol. Together, the end plate  48  and the gasket  50  provide the annular well  47 , which provides a receptacle to receive viscous plastisol material which solidifies and bonds the end cap to the end of the ring of filter media  42 .  
         [0024]     As best illustrated with reference to  FIGS. 1 and 2 , in this embodiment, the top end cap  40  is the same as the bottom end cap  38 . As a result, the same end cap components can be used to form both the top and bottom end caps. The same molds can be used to form the respective end cap components, thus avoiding the need for additional manufacture and inventory of completely different components. As a result, there may be no difference between top and bottom ends of the filter cartridge such that either end can be used to seal against the stand-pipe and the other end used to seal against the adaptor. As used herein, top is used to identify the end cap which is ultimately receives an adaptor.  
         [0025]     Because the end caps are made of the same components, the top end cap  40  also includes an L-shaped end plate  54  and a gasket  55  sealingly received by a hole in the L-shaped end plate  54 . The gasket  55  also provides an opening  56  in fluid communication with the interior of the filter cartridge  18 .  
         [0026]     The housing adaptor  15  is adapted to be releasably connected to the housing lid  14  and to the filter cartridge  18 . To provide the releasable connection, in an embodiment, the housing adaptor  15  includes a plurality of prongs  64  projecting vertically upwards axially from an exterior side of a main disc portion  65 . The prongs  64  are adapted to snap onto corresponding engagement means of the housing lid  14 , particularly engagement means such as ribs, channels, ridges, or merely a sufficiently small cavity, relative to an outer periphery established by the prongs  64 , of the housing lid  14 . The prongs  64  surround a passage  66  extending axially through the housing adaptor  15  and are radially spaced apart providing gaps  67  between adjacent prongs  64 . The passage  66  provides fluid communication to the fluid bypass. Thus, the passage  66  is in fluid communication with dirty fluid entering the cavity  20  via the gaps  67  between the prongs  64 . The illustrated embodiment is described as having prongs  64  to engage the housing lid  14 , however, the invention is not limited to having only prongs  64  and may include alternative connecting means to secure the housing adaptor  15  to the engagement means of the housing lid  14 .  
         [0027]     The housing adaptor  15  is adapted to releasably and sealingly secure the housing adaptor  15  to the top end cap  40  of the filter cartridge  18 . An outer surface  70  of a portion  69  of the housing adaptor  15  is received into and seats with the opening  56  of the top end cap  40  provided by the gasket  55  creating an interference friction fit and seal there between. Specifically, the compression or deflection due to the resiliency in the rubber material of the end cap gasket preferably creates a sufficient force to releasably hold the filter cartridge  18  on the housing adaptor  15 .  
         [0028]     To assist with the sealing and retention functions, the gasket  55  may include an annular rib  72  that extends radially inward from an inner surface  73  of the gasket  55 . The annular rib  72  focuses the seal between the outer surface  70  of portion  69  of the housing adaptor  15  and the gasket  55  by resiliently compressing when the housing adaptor  15  is inserted into the opening  56  of the gasket  55 .  
         [0029]     Furthermore, an interior side of the main disc portion  65  abuts a top surface of the gasket  55  to axially position the housing adaptor  15  relative to the top end cap  40 . The abutment between the disc portion  65  and the top surface of the gasket  55  may also be used to provide the seal between the housing adaptor  15  and the gasket  55 . In this embodiment, the outer diameter of the disc portion  65  of the housing adaptor  15  is smaller than the outer diameter of the top end cap  40 .  
         [0030]     On an interior side, the housing adaptor  15  includes an inner annular flange  68  that depends axially downward and has a valve seat  71 . In this embodiment, the inner annular flange  68  is chamfered to improve the seal of the seat  71  between the housing adaptor  15  and a domed surface  74  of a valve member  76  of the bypass valve  16  (see  FIG. 1 ). The passage  66  extending through the housing adaptor  15  is partially provided by the inner annular flange  68 .  
         [0031]     In an embodiment and shown in  FIG. 3 , the housing adaptor  15  includes a key  80  that extends radially outward from the inner annular flange  68 . Alternatively, the key  80  could extend vertically downward from an interior side of the housing adaptor  15 , see for example key  122  in  FIG. 5 . The key  80  can be used to angularly align the filter cartridge  18  relative to a stand pipe  22 , and unlock a latch (not shown) if provided on the standpipe. Such latched valve devices are known for example as disclosed in U.S. Pat. No. 6,554,139 to Maxwell et al. In any event, the housing as adapted by the reusable adaptor disables this latch device if it is present. It will be appreciated that more than one key may be used if required.  
         [0032]     As shown in  FIG. 1 , the stand pipe  22  extends from and is secured to a base  54  of the housing  12 . The stand pipe  22  may be any metal, plastic or other rigid material. The stand pipe  22  may be adhesively, threadedly or frictionally secured to the base  54 . The stand pipe  22  carries the filter bypass valve  16 .  
         [0033]     The bypass valve  16  includes a mushroom shaped valve member  76  that includes a head  84  and a shaft  86  and is resiliently biased by a coil spring  88 . The head  84  is dome shaped and provides the domed top surface  74  and a flat bottom surface  90 . It is contemplated that the head  84  could be a flat disc without the domed surface  74 . If the head  84  is in the form of a flat disc or other shape, the axial annular flange  68  of the housing adaptor  15  would be more appropriately configured to seal to the flat disc. The shaft  86  is substantially cylindrical in shape and extends vertically downward from the head  84 , however, in other embodiments the shaft could form other shapes.  
         [0034]     The coil spring  88  is carried by and surrounds the shaft  86 . The coil spring  88  is positioned axially between the head  84  and a support flange  92  attached to and radially extending inward from the stand pipe  22 . Particularly, one end of the coil spring  88  abuts the bottom surface  90  of the head  84  and the other end abuts a top side of a support flange  92  to resiliently bias the valve member  76  vertically upwards. The end of the shaft  86 , opposite the end that is attached to the head  84 , includes a plurality of fingers  94  that extend radially outward from the shaft  86  and selectively abut a bottom side of the support flange  92  to connect the valve member  76  to the stand pipe  22 . The portion of the shaft  86  that includes the fingers  94  may be resiliently biased radially inward such that during installation the valve member  76  may be snap fit into the support flange  92  of the stand pipe  22 .  
         [0035]     The filter arrangement  10  is assembled by releasably snapping on the housing adaptor  15  to the housing lid  14  via the snap prongs  64  and also releasably securing the housing adaptor  15  to the filter cartridge  18 . The combination of the housing lid  14 , housing adaptor  15  and filter cartridge  18  is then positioned over the stand pipe  22  such that the stand pipe  22  is received into the interior of the filter cartridge  18  through the first opening  48  in the bottom end cap  38 . Particularly, the stand pipe  22  is received through the hole in the gasket  50  inserted into the first opening  48  of the bottom end cap  38 . After the housing lid  14  bottoms out on the housing  12 , the housing lid  14  is then screwed to the housing  12 . As the housing lid  14  is screwed to the housing  12 , the gasket  50  of the bottom end cap  38  seats to the outer surface  52  of the base  54  to prevent short-circuiting of fluid from the dirty side of the filter to the clean side of the filter.  
         [0036]     Furthermore, as the housing lid  14  is screwed to the housing  12 , the housing adaptor  15  seats with the valve member  76 . Particularly, the beveled inner annular flange  68  seats on the domed surface  74  of the head  84 . As the inner annular flange  68  seats to the head  84 , the coil spring  88  may begin to compress vertically downward. It will be appreciated that the seat between the inner annular flange  68  of the housing adaptor  15  and the domed surface  74  of the head  84  creates a seal that prevents dirty fluid from short-circuiting the filter cartridge  18  through the top end cap  40 .  
         [0037]     In operation, the bypass valve  16  acts to selectively allow dirty fluid to short-circuit the filter cartridge  18  during high pressure situations. One specific high pressure situation is when the filter media  36  has become sufficiently plugged with filtered contaminates such that an insufficient amount of fluid may flow through the filter media  36 . Furthermore, as the filter media  36  becomes increasingly plugged with filtered contaminates, the pressure differential across the filter media  36  between the high pressure dirty fluid side and lower pressure clean fluid side increases. The bypass valve may open at other high pressure situations such as cold startup when the filtered fluid may be thicker than at normal operating temperatures.  
         [0038]     At some predetermined pressure differential, the load created by the dirty fluid acting on the domed surface  74  of the head  84  will be greater than the load acting on the bottom surface  90  of the head  84  by the coil spring  88  and the clean fluid such that the valve member  76  will be actuated and move vertically downward. As the valve member  76  moves vertically downward, the inner annular flange  68  and the head  84  no longer contact, thereby opening the bypass valve  16 , allowing dirty fluid to short circuit the filter cartridge  18 . It will be appreciated, that the predetermined pressure differential at which the bypass valve  18  will open can be varied by providing a coil spring  88  with a different stiffness.  
         [0039]     The connection between the housing adaptor  15  and the top end cap  40 , particularly the gasket  55  of the top end cap  40 , explained previously, provides for a relatively easy replacement of a spent or clogged filter cartridge  18 . After the housing lid  14  and filter cartridge  18  attached thereto via the housing adaptor  15  are removed from the housing  12 , the spent filter cartridge  18  may be pulled away from and disconnected from the housing adaptor  15 . The housing adaptor  15  has a stronger snap-on connection than the interference fit between the cartridge and housing adaptor, such that the housing adaptor  15  remains secured to the housing lid  14  for reuse. A new clean filter cartridge  18  can then be slid onto and connected to the housing adaptor  15 . Specifically, one of the end caps of the new filter cartridge is placed onto the housing adaptor  15 .  
         [0040]     It will be appreciated that the reusable housing adaptor  15  allows simpler and more economical filter cartridges to be manufactured because in an embodiment both end caps  38 ,  40  are identical and the more complex structure, the housing adaptor  15 , needs only to be manufactured a single time and not continually manufactured and provided with each replacement filter cartridge.  
         [0041]     An alternative embodiment of an adaptor in accordance with the present invention is provided in  FIGS. 4 and 5 . The adaptor  100  is sealingly received in an opening in the top end cap  102  of the filter cartridge  104 . The top end cap  102  in this embodiment is different than the top end cap  40  of the previous embodiment. In this embodiment, the well  147  in which the filter media is sealingly bonded at the upper end is provided by two integral annular walls that depend axially from the end cap  102 , rather than by different walls depending from the cap  54  and the gasket  55 , respectively.  
         [0042]     Furthermore, the opening in the top end cap  102  is provided by an annular sealing lip  106  which is formed into the plastic material of the top end cap  102 . The reduced thickness and curved shaped of the sealing lip  106  provides for resilient deflection of the sealing lip  106  for providing a wiper/lip seal. The sealing lip  106  engages and seals with the adaptor  100  when the adaptor  100  is received by and inserted into the opening of the top end cap  102 . The sealing lip  106  presses radially inward against a radially outer surface  108  of the adaptor  100  to engage and secure the adaptor  100  therein as well as create a radial seal therebetween. In this embodiment, the sealing lip  106  is tapered inward to also provide a deflection means to assist when installing the adaptor  100 .  
         [0043]     In an embodiment, the adaptor  100  includes a plurality of wedge shaped catches  110  vertically spaced apart from a radially extending annular flange  112 . The catches  110  and the annular flange  112  facilitate a snap-on connection of the adaptor  15  to the sealing lip  106 . The sealing lip  106  abuts with the bottom shoulder  114  of the protrusions  110  vertically above the sealing lip  106  and with the radial annular flange  112  vertically below the sealing lip  106 .  
         [0044]     However, because the sealing lip  106  creates a radial seal with the outer surface  108  it is contemplated that in an embodiment the sealing lip  106  and outer surface  108  can create a sufficiently tight friction fit that the snap-on catches  110  are not required.  
         [0045]     The radial annular flange  112  provides the additional function of preventing the adaptor  100  from being pushed completely through the opening in the top end cap  102  during assembly. As the adaptor  100  is appropriately positioned and seated within the opening, the radial annular flange  112  bottoms out on the bottom of the sealing lip  106  to prevent further axial movement. The radial annular flange  112  further prevents the adaptor  100  from being pushed out of position when the axial annular flange  116  seats with a valve member, as explained previously.  
         [0046]     The adaptor  100  includes a plurality of vertically extending prongs  120 . These prongs  120  are adapted to secure the adaptor  100 , and the filter cartridge  104  to which it is attached, to a filter housing, as shown and described previously in association with the first embodiment. The prongs  120  are radially spaced apart from one another and surround a passage  121  provided by the axial annular flange  112 . The passage  121  provides fluid communication with the valve bypass. When the axial annular flange  116  is seated on a valve member (not shown) the passage  121  allows fluid to act on the valve member.  
         [0047]     As illustrated in  FIG. 5 , the adaptor  100  may include a key  122  on an interior side. The key  122  extends vertically downward from an interior side of the radial annular flange  112 . However, similar to the previous embodiment, the key  122  could extend radially from the axial annular flange  116 . The key  122  may function to properly align the filter cartridge  104  relative to a stand pipe or unlock a latch (not shown) if provided on the standpipe. The adaptor  100  may include a plurality of keys  122 .  
         [0048]      FIG. 6  illustrates an alternative embodiment of a housing adaptor  130  in accordance with the present invention. The housing adaptor  130  is similar to the housing adaptor of  FIG. 2  and includes a plurality of angularly spaced apart prongs  132  for securing the housing adaptor  130  to an external housing (see  FIG. 1 ) and an inner annular flange  134  that has a valve seat  136 . The housing adaptor  130  interacts with the top end cap  142  of the filter cartridge  144 . The top end cap  142  includes an L-shaped end plate  146  and a gasket  148  sealingly received by a hole in the L-shaped end plate  146 . The gasket  148  and end plate  146  may be potted to filter media, as explained previously. The gasket  148  includes an opening  150  in fluid communication with the interior of the filter cartridge  144 . The inner annular flange  134  of the housing adaptor  130  passes through the opening  150  in the gasket  148 .  
         [0049]     The gasket  148  includes a head portion  152  that is annular and extends radially outward. The head portion  152  has a larger diameter than the hole in the L-shaped end plate  146  and abuts the top  154  of the L-shaped end plate  146 . An axial seal may be provided between the head portion  152  and the top  154  of the L-shaped end plate  146 .  
         [0050]     The housing adaptor  130  includes an outer annular flange  158  that extends vertically. The outer annular flange  158  interacts with the head portion  152  of the gasket  148 . The housing adaptor  130  may abut the top of the head portion  152  of the gasket  148  to provide an axial seal therebetween. The outer annular flange  158  engages the radially outer surface of the head portion  152  to secure the housing adaptor  130  to the end cap  142 , and consequently the filter cartridge  144 . A radial seal is formed between the outer annular flange  158  of the housing adaptor  130  and the head portion  152  of the gasket  148 . To focus the engagement and seal between the head portion  152  and the outer annular flange  158 , the radial outer surface of the head portion  152  includes one or more annular ribs  164  that compress and form a press-fit connection when the housing adaptor  130  is temporarily secured to the gasket  148 .  
         [0051]     The gasket  148  and the outer annular flange  158  of the adapter  130  have a sliding press-fit engagement. When a spent filter cartridge  144  is replaced and removed from the housing adaptor  130 , the housing adaptor  130  will typically remain with the external housing lid, such that simply a new filter element cartridge  144  can be installed.  
         [0052]     A further alternative embodiment of an adaptor according to the present invention is illustrated in  FIG. 7 . The adaptor  168  includes a plurality of angularly spaced apart prongs  169  for securing the adaptor to an external housing and an inner annular flange  170  that has a valve seat  171 . The adaptor  168  interacts with the top end cap  172  of the filter cartridge  173 . The top end cap  172  includes an L-shaped end plate  174  and a gasket  175  sealingly received by a hole in the L-shaped end plate  174 . The gasket  175  includes an opening in fluid communication with the interior of the filter cartridge  173 .  
         [0053]     The gasket  175  includes a main body portion  176  that is sealingly received by the hole in the L-shaped end plate  174 . An outer annular flange  177  extends radially outward from the main body portion  176 . The outer annular flange  177  has a larger diameter than the hole in the L-shaped end plate  174  and abuts with the top of the L-shaped end plate  174  and may provide an axial seal therebetween. The gasket  175  further includes an inner flange  178  that extends radially inward from the main body portion  176  and is L-shaped.  
         [0054]     The adaptor  168  includes an outer annular flange  179  that has an L-shaped cross-section. The outer annular flange  179  sealingly interacts with and engages the gasket  175 . The outer annular flange  179  of the adaptor  168  includes an upward extending portion  180  that, in an assembled condition, is positioned radially between the main body portion  176  and the inner flange  178  of the gasket  175 . The inner flange  178  may include an annular rib  181  that resiliently compresses to focus the seal and engagement between the gasket  175  and the adaptor  168 . Alternatively, the annular rib  181  could extend from the main body portion  176  of the gasket  175 .  
         [0055]     A further alternative embodiment of an adaptor in the form of a housing adaptor in accordance with the present invention is illustrated in  FIG. 8 . The housing adaptor  183  is similar in some respects to the adaptor  100  of  FIG. 4 . However, the housing adaptor  183  is sealingly received in an opening in the top end cap  184  of the filter cartridge  185  from a top side  186  rather than from a bottom side. The top end cap  184  includes a sealing lip  187  that engages and forms a radial seal between an outer surface of the housing adaptor  183 .  
         [0056]     The top end cap  184  and the sealing lip  187  in this embodiment are similar to the embodiment in  FIG. 4 . However, because the housing adaptor  183  inserts into the hole in the top end cap  184  from the top side  186 , the taper of the annular sealing lip  187  of the top end cap  184  is reversed such that the sealing lip  187  tapers radially inward in a downward direction, as illustrated in  FIG. 8 .  
         [0057]     The housing adaptor  183  is similar to previous embodiments, as it includes a plurality of angularly spaced apart prongs  189  for connecting the housing adaptor  183  to an external filter housing, as illustrated and described previously. Similarly, the housing adaptor  183  includes an inner annular flange  190  that has a valve seat  191 .  
         [0058]     The housing adaptor  183  further includes an outer annular flange  192  that extends radially outward from the housing adaptor  183 . When the top end cap  184  receives the housing adaptor  183 , the outer annular flange  192  abuts the sealing lip  187  to position the housing adaptor  183  relative to the top end cap  184 .  
         [0059]     As illustrated in  FIG. 8 , the housing adaptor  183  may include a key  193  on an interior side. The key  193  extends vertically downward from an interior side of the housing adaptor  183  and functions as explained previously.  
         [0060]     Furthermore, in an embodiment, the housing adaptor  183  may include a plurality of wedge shaped catches  194  vertically spaced apart from the outer annular flange  192 . The catches  194  facilitate a snap-on connection of the housing adaptor  183  to the sealing lip  187 , as explained previously. However, it is contemplated that in an embodiment the engagement and friction fit between the sealing lip  187  and the housing adaptor  183  may be sufficiently strong that neither the outer annular flange  192  nor the wedge shaped catches  194  are required. However, in an embodiment, the engagement between the sealing lip  187  and the housing adaptor  183  is less than the connection between the prongs  189  and the external housing such that the housing adaptor  183  would remain with the housing when replacing a spent filter cartridge  185 . This is thus a significant advantage over the embodiment of  FIG. 4 .  
         [0061]     For clarity, annular as used herein is meant to include forming a ring or otherwise ring-shape including, but not limited to, circular, oval, rectangular or polygonal, or other shapes including a ring-like shape whether with flat or curved surfaces or a combination thereof.  
         [0062]     All references, including publications, patent applications, and patents cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.  
         [0063]     The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) is to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.  
         [0064]     Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.