Abstract:
A water separating fuel filter is provided with a sensor at its bottom portion which is not removable in a direction away from the housing structure of the filter mechanism. In other words, if the sensor is removable at all, it must be removed in a direction which requires the sensor to move through the cavity of the housing structure of the filter while preventing an internal end of the sensor from passing in a direction away from the cavity and through a portion of the wall of the housing structure through which the sensor extends during operation. This eliminates the likelihood of a sensor being inadvertently removed from the housing structure and not properly replaced prior to subsequent operation of a fuel system of an internal combustion engine. This, in turn, prevents the condition wherein an opening at the bottom portion of the fuel filter housing structure can allow liquid fuel to flow from the fuel system into the bilge of a watercraft.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention is generally related to a water detecting fuel filter and, more particularly, to a filter structure which limits the ways in which a water detecting sensor can be removed from a housing structure of the water separating fuel filter device. 
         [0003]    2. Description of the Related Art 
         [0004]    Many different types of water separating fuel filters and water detectors are known to those skilled in the art. The purpose of the filter is to remove water from liquid fuel. The purpose of the water detecting sensor is to determine when water, is within the structure of the fuel filter, is of a sufficient quantity to necessitate its removal. 
         [0005]    U.S. Pat. No. 4,515,690, which issued to Yasuhara on May 7, 1985, describes a fuel supply system for diesel engines. An apparatus is provided informing when a filter located in a fuel passage between a fuel tank and a fuel injection pump has clogged a predetermined amount. The apparatus is responsive to fuel pressure downstream of the filter to provide an indication when the sensed pressure is below a predetermined value. A device for draining water separated from the fuel is also described. 
         [0006]    U.S. Pat. No. 4,562,431, which issued to Jahnke et al. on Dec. 31, 1985, describes a fuel filter unit with water content indicator. Corrosion of a water sensor resulting from the passage of considerable electric current through it while it is in contact with water is prevented in a motor fuel filter equipped for water separation by interrupting or greatly reducing the current passing through the sensor after the sensor has given a signal indicating the presence of water in sufficient quantity to require draining soon. The warning provided to the vehicle driver is maintained thereafter either by a signal storage unit or by causing current diverted from the sensor to flow through the substitution resistor or a shunt transistor. 
         [0007]    U.S. Pat. No. 4,594,892, which issued to Asmundsson on Jun. 17, 1986, describes a capacitance probe for liquid level measuring systems. A liquid level measurement capacitance probe is disclosed comprising an elongated outer capacitor tube, an elongated inner tube coaxially mounted within the outer capacitor tube to form a capacitor annulus therebetween with the inner tube having a plurality of longitudinally extending capacitor elements cooperating with the outer capacitor tube to form a plurality of individual capacitor units, a connector unit for electrically connecting the capacitor units to an electronic circuit processor for measuring capacitance values of the capacitor units in calculating a fluid level, a filter for separating water from fuel flowing from the storage tank to be measured to the capacitor annulus, the filter having an annular housing mounted about the outer capacitor tube with an inlet port adapted for fluid communication with the storage tank and an outer port connected to the capacitor annulus between the inner and outer capacitor tube for delivery of filtered fuel to the annulus. 
         [0008]    U.S. Pat. No. 5,993,675, which issued to Hagerthy on Nov. 30, 1999, describes a fuel water separator for marine and diesel engines. The device provides a method for separating fuel from water in a marine propulsion system and a reusable device for separating water from fuel in marine and diesel engines thereby preventing or limiting water from entering the combustion process of the engine. 
         [0009]    U.S. Pat. No. 6,676,841, which issued to Akins et al. on Jan. 13, 2004, describes a water-in-fuel abuse detection system. It provides a way to determine if a vehicle operator has ignored a conventional in-fuel indicator light and continued to operate the vehicle beyond a certain threshold. The system includes a sensor positioned in a fuel filter capable of separating an amount of water from a source of fuel. The sensor is operatively connected to a software routine, as well as to a conventional indicator light that illuminates to alert a vehicle operator that water must be purged from the fuel filtration system. 
         [0010]    U.S. Pat. No. 6,923,165, which issued to Draves et al. on Aug. 2, 2005, discloses a fuel system for a marine propulsion device. The system is provided with a fuel distribution member that has a plurality of passages formed within its unitary structure to allow a water separating fuel filter and a pressure regulator to be attached directly to the fuel distribution member without the need of conduits and hoses connected therebetween. The fuel is received from a mechanical fuel pump and directed through the water separating fuel filter to a fuel manifold that includes first and second fuel rails. The fuel is cooled and pumped through a high pressure fuel filter as it flows to the fuel manifold. The pressure regulator has a pressure relief conduit that returns fuel to the fuel filter for recirculation. 
         [0011]    The patents described above are hereby expressly incorporated by reference in the description of the present invention. 
       SUMMARY OF THE INVENTION 
       [0012]    A filter device, made in accordance with the preferred embodiment of the present invention, comprises a housing structure which defines a cavity therein, a filter medium disposed within the housing structure, and a sensor extending through a portion of a wall of the housing structure. The sensor has an internal end disposed within the cavity and an external end which extends away from the housing structure. The sensor is configured to prevent the sensor from being removed from the housing structure in a direction which causes the internal end to pass through the portion of the wall in a direction away from the cavity. 
         [0013]    In a particularly preferred embodiment of the present invention, the filter device is a water separating fuel filter. The sensor can be removable from the portion of the wall in a direction into the cavity. The portion of the wall can be proximate a bottom of the housing structure when the filter is operative. In other words, when the filter device is attached to a fuel system of an internal combustion engine, the portion of the wall is disposed at a bottom portion of the housing structure. The sensor can be a water detecting sensor and can comprise an electrically conductive core. The electrically conductive core can be made of stainless steel. The sensor can further comprise an electrically insulative member disposed between the electrically conductive core and the portion of the wall. The electrically insulative member can be made of plastic, an elastomeric material, or a ceramic material. It should be understood that the specific material used to provide the electrically insulative member is not limiting to the present invention. 
         [0014]    The sensor can be prevented from being removed from the housing structure, in a direction which causes the internal end to pass through the portion of the wall in a direction away from the cavity, by a flange element which is attached to the sensor and disposed within the cavity. The portion of the wall of the housing structure can be electrically conductive. 
         [0015]    The filter device of the present invention can further comprise a boss which is welded to the portion of the wall with the sensor being threaded into the boss. Alternatively, the sensor can be irremovably attached to the portion of the wall. In certain embodiments of the present invention, it can further comprise a thermally insulative region disposed between the external end of the sensor and the portion of the wall. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    The present invention will be more fully and completely understood from a reading of the description of the preferred embodiment in conjunction with the drawings, in which: 
           [0017]      FIG. 1  is a sectioned isometric view of one embodiment of the present invention; 
           [0018]      FIG. 2  is a sectioned isometric view of an alternative embodiment of the present invention; 
           [0019]      FIG. 3  is a third embodiment of the present invention; 
           [0020]      FIG. 4  is a fourth embodiment of the present invention; and 
           [0021]      FIG. 5  is an enlarged view of a portion of  FIG. 4 . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0022]    Throughout the description of the preferred embodiment of the present invention, like components will be identified by like reference numerals. 
         [0023]      FIG. 1  is an isometric section view of a water separating fuel filter  10  made in accordance with a preferred embodiment of the present invention. It comprises a housing structure  14  which defines a cavity  16  therein. A filter medium  20  is disposed within the cavity  16  of the housing structure  14 . When the water separating fuel filter  10  is attached to a fuel system of an internal combustion engine, fuel is caused to flow into the housing structure  14  in the region of the cavity  16  surrounding the outer circumferential surface of the filter medium  20 . The fuel then flows radially inwardly through the filter medium material and is conducted to the cylinders of the engine. The filter medium  20  is particularly configured to be impermeable to water that may be entrained within the fuel. This water remains in the portion of the cavity  16  surrounding the filter medium  20  and, because the water is denser than the fuel, it collects in the bottom region of the housing structure  14 . A sensor  30  extends through a portion  32  of a wall  34  of the housing structure  14 . The sensor  30  has an internal end  40  disposed within the cavity  16  and an external end  42  which extends away from the housing structure  14 . The sensor  30  is configured to prevent the sensor from being removed from the housing structure  14  in a direction which causes the internal end  40  to pass through the portion  32  of the wall  34  in a direction away from the cavity  16 . In other words, the sensor  30  shown in  FIG. 1  is prevented from being removed from the housing structure  14  in a downward direction in the illustration. This removal in a downward direction in  FIG. 1  would cause the internal end  40  to pass through the portion  32  of the wall  34  through which the sensor  30  extends. 
         [0024]    In the embodiment of the present invention shown in  FIG. 1 , the sensor  30  is a water detecting sensor that comprises an electrically conductive core  46 . In a particularly preferred embodiment of the present invention, this electrically conductive core  46  is made of stainless steel. The sensor  30  further comprises an electrically insulative member  48 , in a preferred embodiment of the present invention, which is disposed between the electrically conductive core  46  and the portion  32  of the wall  34 . This electrically insulative member  48  can be made of plastic, an elastomeric material, or a ceramic material in a particularly preferred embodiment of the present invention. 
         [0025]    The embodiment of the present invention shown in  FIG. 1  also comprises a boss  50  which can be welded to the portion  32  of the wall  34 . This boss  50  can also be threaded to receive threads formed on an outer surface of the electrically insulative member  48 . 
         [0026]    With continued reference to  FIG. 1 , a flange element extends outwardly from the electrically insulative member  48 . This flange element  58  is provided with six flat sides which facilitate the tightening of the sensor  30  to the boss  50 . It can also be seen that the flange element  58  prevents the downward movement of the insulative member  48  through the opening described by the boss  50 . As a result, since the electrically conductive core  46  is attached to the electrically insulative member  48 , the flange element  58  prevents the downward movement of the sensor  30  through the opening formed in the boss  50 . The only way that the sensor  30  can be removed from the housing structure  14  is in an upward direction through the cavity  16 . With the filter medium  20  removed from the housing structure  14 , the sensor  30  can be loosened from its threaded attachment to the boss  50  and moved in an upward direction in  FIG. 1  through the cavity  16  when the sensor  30  must be replaced. Otherwise, the sensor  30  is configured to prevent its removal in the opposite direction downwardly through the portion  32  of the wall  34 . 
         [0027]    With continued reference to  FIG. 1 , it can also be seen that a spring  60  is provided to exert an upward force on the filter medium  20 . In its most basic form, the sensor  30  operates by detecting an electric current conducted by water. This current between the internal end  40  and the housing structure  14  indicates that water is present in the region of the internal end  40 . This represents the presence of sufficient water within the cavity  16  to require replacement of the water separating fuel filter or, at a minimum, the removal of the water contained within the cavity  16 . 
         [0028]      FIG. 2  shows an alternative embodiment of the present invention. The core  46  is coated with a dielectric coating such as an epoxy  70 . The internal end  40  remains uncoated. Similarly, the external end  42  is uncoated. A high temperature, fuel resistant elastomeric material  74 , such as fluoroelastomer (FKM) or perfluoroelastomer (FFKM) is provided as an electrically insulative structure and also a seal between the core  46  and the boss  50 . In addition, an adhesive  76  is provided to bond the core  46  to the boss  50  and to also provide a redundant seal around the sensor  30 . The shape of the core  46  and its coating  70  is configured to prevent the removal of the core  46  in a downward direction through the boss. In fact, the use of the adhesive  76  is intended to prevent the removal of the sensor  30  from the housing structure  14  without the destruction of the water separating fuel filter  10 . 
         [0029]    Regulations relating to inboard marine engines require that the engines must sustain a 2.5 minute fire test. The various high temperature insulator concepts associated with the present invention help to assure that the structure will pass the fire test requirement.  FIG. 3  shows an alternative embodiment of the present invention. A welded insert  80  provides a heat isolation air cavity  84  surrounding a lower portion of the core  46 . Air, which is temporarily trapped within the air cavity  84  when the mating electrical connector is present, delays the effect of heat on the elastomeric material  88  which provides a seal between the liquid in the cavity  16  and the surrounding area outside of the housing structure  14  and below the portion  32  of the wall  34 . This elastomeric material  88  also provides electrical insulation between the core  46  and the upper portion  90  of the welded insert  80 . The diametric configuration of the core  46  is configured to prevent the removal of the sensor  30  from the housing structure  14  in a downward direction which would cause the internal end  40  to pass through the portion  32  of the wall  34  through which the sensor  30  extends. The embodiment shown in  FIG. 3  is intended to prevent the sensor  30  from being removed from the housing structure  14  in any direction. 
         [0030]    The embodiment of the present invention shown in  FIG. 4  provides a welded boss  50  that more or less completely encloses the air cavity  84  when the mating electrical connector is present. The electrically insulative member  48  is provided with the flange  58 , as described above in conjunction with  FIG. 1 , which assists in the assembly of the sensor  30  into the boss  50 . In addition, the flange  58  prevents the downward movement of the sensor  30  through the portion  32  of the wall  34  through which the sensor  30  extends. The other components identified in  FIG. 4  are generally similar to their counterparts which have been described above. 
         [0031]      FIG. 5  is an enlarged view of the lower portion of  FIG. 4 . The heat isolation air cavity  84  is contained within the boss  50  which, in turn, is welded to the portion  32  of the wall  34  through which the sensor  30  extends. A sealing washer made of Teflon coated steel  100  is provided under the flange  58  and an FFK or FFKM elastomer o-ring  104  is disposed under the sealing washer  100  to provide additional sealing. The electrically insulative member  48  is made of a high temperature electrically insulative plastic that is molded over the core  46  prior to its insertion into the upper portion of the boss  50 . This electrically insulative member  48  is provided with external threads that are received in threads formed in an internal opening of the boss structure. To further add to the redundant sealing, a sealing compound may be applied to the threads on the electrically insulative member  48  prior to installation into the boss  50 . 
         [0032]    With continued reference to  FIG. 5 , the heat isolation air cavity  84  is intended to slow the potentially destructive effect that a fire below the housing structure  14  can have on the non-metallic portions of the heat sensor  30 . This air cavity  84  is not intended to prevent any such heat damage but, instead, is intended to delay the formation of a path through or around the sensor structure through which liquid fuel can flow from the cavity  16  to a region below the portion  32  of the wall  34  through which the sensor extends. 
         [0033]    With reference to  FIGS. 1-5 , it can be seen that a filter device made in accordance with various preferred embodiment of the present invention comprises a housing structure  14  which defines a cavity  16  therein. A filter medium  20  is disposed within the housing structure  14 . A sensor  30  extends through a portion  32  of a wall  34  of the housing structure  14 . The sensor  30  has an internal end  40  disposed within the cavity  16  and an external end  42  which extends away from the housing structure  14 . The sensor  30  is configured to prevent the sensor from being removed from the housing structure  14  in a direction which causes the internal end  40  to pass through the portion  32  of the wall  34  in a direction away from the cavity  16 . In other words, in the embodiments shown in the figures, the sensor  30  is prevented from being removed in a downward direction which causes the internal end  40  to move out of the cavity  16  in a direction which causes it to pass through the portion  32  of the wall  34 . In certain embodiments of the present invention, the sensor  30  can be removed in an upward direction into and through the cavity  16  which causes the external end  42  to move upwardly through the portion  32  of the wall  34  and into the cavity  16 . The primary purpose of this configuration is to prevent the inadvertent removal of the sensor in a downward direction which would expose an opening through the portion  32  of the wall  34  through which liquid fuel can flow. In this way, the present invention prevents the removal of the sensor  30  from the housing structure  14  without the complete removal of the housing structure  14  from the fuel system of an internal combustion engine. As a result, inadvertent omission or removal of the sensor  30  will not cause a flow of liquid fuel into the bilge portion of a marine vessel. 
         [0034]    The filter device can be a water separating fuel filter  20  and the sensor  30  can be removable from the portion  32  of the wall  34  in a direction into the cavity  16  defined by the housing structure  14 . The portion  32  of the wall  34  can be proximate a bottom of the housing structure when the filter is operative and connected to a fuel system of an internal combustion engine. The sensor  30  can be a water detecting sensor and it can comprise an electrically conductive core  46  which can be made of stainless steel. The sensor  30  can also comprise an electrically insulative member  48  disposed between the electrically conductive core  46  and the portion  32  of the wall  34 . The electrically insulative member  48  can be made of plastic, an elastomeric material, a ceramic material, or any other suitable electrically insulative material. In one embodiment of the present invention, the sensor  30  is prevented from being removed from the housing structure  14 , in a direction which causes the internal end  40  to pass through the portion  32  of the wall  34  in a direction away from the cavity  16 , by a flange element  58  which is attached to the sensor  30  and disposed within the cavity  16 . The portion  32  of the wall  34  can be electrically conductive. A boss  50  can be welded to the portion  32  of the wall  34 . The sensor  30  can be threaded into the boss  50 . 
         [0035]    In certain embodiments of the present invention, the sensor  30  is irremovably attached to the portion  32  of the wall  34 . A thermally insulative region, or air cavity  84 , can be disposed between the external end  42  of the sensor  30  and the portion  32  of the wall  34 . 
         [0036]    Although the present invention has been described with particular specificity and illustrated to show several preferred embodiments, it should be understood that alternative embodiments are also within its scope.