Abstract:
A fuel tank inlet assembly for receiving fuel during automatic vehicle fueling and a pump assembly for delivering fuel during automatic vehicle fueling and the combination thereof. The fuel tank inlet assembly includes a fuel conduit with a fuel exit for operative connection with a fuel tank and the pump assembly includes a fuel nozzle for operative connection with the inlet assembly. One preferred embodiment of the invention includes a positioning system which utilizes inductive triangulation to connect the pump assembly to the inlet assembly.

Description:
FIELD OF THE INVENTION  
         [0001]    This invention relates to an apparatus for transferring a liquid from fuel storage to a vehicle fuel tank and, more particularly, to automatic fueling of vehicles at retail fueling stations.  
         BACKGROUND OF THE INVENTION  
         [0002]    Retail selling of gasoline and other vehicle fuels is a major industry throughout the world. By one recent estimate, there are on the order of 200,000 retail fuel service stations in the United States alone.  
           [0003]    Such stations are referred to as either “full service” stations or “self service” stations, depending on whether a station employee or the customer himself is responsible for manipulating the pump, fuel hose, and valve structure into position for fueling the vehicle. In either case, however, substantial human activity is required by a person outside the vehicle to accomplish the fueling of the vehicle fuel tank.  
           [0004]    In view of the extremely high volume of retail fuel sales, the high costs of providing full service, and the inconvenience for a customer of all the manipulative steps necessary for vehicle fueling, a need exists for improved fueling station methods and apparatus. In particular, a need exists for practical automatic fueling apparatus and methods.  
           [0005]    A number of attempts have been made in the prior art to improve retail fueling procedures. Some examples include the disclosures of the following United States Pat. Nos.:  
           [0006]    U.S. Pat. No. 3,095,020 (Darwin)  
           [0007]    U.S. Pat. No. 3,364,940 (Ginsburgh et al.)  
           [0008]    U.S. Pat. No. 3,410,320 (Ginsburgh et al.)  
           [0009]    U.S. Pat. No. 3,502,117 (Nebelsiek et al.)  
           [0010]    U.S. Pat. No. 3,527,268 (Ginsburgh)  
           [0011]    U.S. Pat. No. 3,530,906 (Ginsburgh et al.)  
           [0012]    U.S. Pat. No. 3,536,109 (Ginsburgh et al.)  
           [0013]    U.S. Pat. No. 3,642,036 (Ginsburgh et al.)  
           [0014]    U.S. Pat. No. 4,681,144 (Horvath et al.)  
           [0015]    U.S. Pat. No. 4,712,709 (Horvath et al.)  
           [0016]    U.S. Pat. No. 4,881,581 (Hollerback)  
           [0017]    These patents describe various methods and types of apparatus for facilitating fueling and for automatic fueling using overhead, on-ground or below-ground equipment. However, the automatic fueling systems and methods disclosed in the prior art have substantial inherent practical problems.  
           [0018]    A need has existed for an improved practical approach to automatic engagement of a filling nozzle with fuel tank intake devices on vehicles. In particular, there is a need for an improved fuel-intake device which can mounted lateral to the tank and can readily be engaged automatically by a fuel nozzle for filling the tank through the a fuel conduit connected to the tank.  
           [0019]    In addition, there is a need for automatic fueling assemblies which do not require costly retrofitting of vehicle fuel tanks. Furthermore, there is a need for automatic fueling assemblies which provide for connection of the pump to the vehicle using advanced positioning systems which do not require powered devices on the vehicle.  
         OBJECTS OF THE INVENTION  
         [0020]    It is an object of this invention, in the field of automatic vehicle fueling, to provide an improved fueling assembly for fueling conventional vehicle tanks without requiring costly retrofitting of the tanks.  
           [0021]    Another object of the invention is to provide a vehicle fuel tank inlet assembly which utilizes the existing fuel port on a vehicle&#39;s fuel tank and avoids the need for drilling or replacement of fuel tanks.  
           [0022]    Another object of the invention is to provide a vehicle fuel tank inlet assembly which prevent fuel leaks from the fuel tank.  
           [0023]    Another object of this invention is to provide a fueling assembly for fueling vehicle tanks which utilizes an advanced positioning system to locate the vehicle fuel inlet and move the pump nozzle toward the inlet without need of a powered signal or response from the vehicle.  
           [0024]    Another object is to provide a vehicle fuel tank inlet assembly which can be mounted to a vehicle at a position lateral to the fuel tank and is connected to the fuel tank using a flexible conduit, such that impacts to the inlet assembly are not transferred to the tank.  
           [0025]    Still another object of the invention is to provide a pump assembly for automatic vehicle fueling which includes a positioned system using inductive triangulation to locate the fuel inlet.  
           [0026]    Yet another object of the invention is to provide a fueling assembly for automatic fueling which provides for easy installation and uses less space in the vehicle.  
           [0027]    These and other objects of the invention will be apparent from the following descriptions and from the drawings.  
         SUMMARY OF THE INVENTION  
         [0028]    This invention is an improved automatic vehicle fueling assembly for use with a vehicle fuel tank and fuel line. The invention represents a significant advance over the state of the art by providing novel elements, including a fuel tank inlet assembly and a pump assembly for delivering fuel to a fuel tank.  
           [0029]    Before operation of the automatic vehicle fueling assembly, a vehicle must be driven into position over the pump assembly. While such vehicle positioning is occurring, the pump assembly is positioned below the surface of the ground and is covered by a door or doors, preferably a pair of sliding doors which are generally flush with the ground. The doors are subsequently opened to expose the pump assembly. Lines or other guidance means on or beside the path of the vehicle enable the driver to move the vehicle into an approximate position at which the pump assembly can extend into contact with the fuel tank inlet assembly as described below.  
           [0030]    The automatic vehicle fueling assembly includes a fuel tank inlet assembly having a fuel conduit with a fuel entrance and exit for operative connection with a fuel tank and a pump assembly with a fuel nozzle defining a passageway for fuel and providing for operative connection to the fuel entrance. The fuel conduit preferably includes a flexible fuel hose having a first end for operative connection to the fuel nozzle during fueling and a second end operatively connected to the fuel tank.  
           [0031]    A certain preferred fuel tank inlet assembly includes a fitting with at least a first, second and third opening. The first opening is provided for operative connection to the fuel nozzle during fueling, the second opening is provided for operative connection to the fuel line, and the third opening is provided for operative connection to the fuel tank. In a most preferred embodiment, the fitting is a “Y”-shaped fitting, though it could also be a “T”-shaped fitting or of any other shape. The inlet assembly also preferably includes a first valve for controlling fuel flow through the first opening and a second valve for controlling fuel flow through the second opening. The first and second valves are preferably spring loaded and allow unidirectional fuel flow toward the tank and prevent fuel from “back flowing” from the tank to either the fuel exit or the manual fueling position.  
           [0032]    In a certain preferred embodiment the fuel tank inlet assembly further includes a fuel inlet adapter connected with respect to the first end of the fuel hose. The fuel inlet adapter is preferably mounted to the vehicle (preferably to the underside of the trunk) and has an inlet cavity for receiving the fuel nozzle. In a most preferred embodiment, flexible sealing doors extend into the inlet cavity to provide sealing between the nozzle and inlet adapter and a slide cover covers the inlet cavity and prevents debris from entering the cavity. The slide cover is preferably formed so as to open upon contact with the fuel nozzle.  
           [0033]    The preferred pump assembly includes a frame which supports the nozzle and is positioned underground, below the vehicle, before fueling and is upwardly moveable to provide operative connection between the nozzle and the fuel entrance. The preferred pump assembly also includes a nozzle sheath having a sheath cavity in which the nozzle is positioned before fueling, and a collar connected with respect to the nozzle sheath and formed for mating engagement with the fuel entrance. The preferred nozzle sheath is compressible such that when upward movement of the frame causes the collar to contact the fuel entrance, the sheath stops moving upward and the nozzle continues to move upward out of the sheath cavity and into the inlet cavity. The sheath may be comprised of a telescopic cylinder and/or may include compression springs at the connection points between the sheath and the collar and frame.  
           [0034]    The frame is preferably connected with respect to at least one riser which powers upward and downward movement of the frame and to a lateral movement device which moves the frame so that the nozzle is substantially aligned with the fuel inlet adapter. In a most preferred embodiment, the frame is connected to the lateral movement device through the riser. The lateral movement device is preferably a slide plate positioned underground which provides for movement in the X and Y direction, i.e., perpendicular directions in the substantially horizontal plane.  
           [0035]    The fueling assembly preferably further includes a positioning system for locating the fuel inlet adapter and controlling the lateral movement device so that the nozzle is substantially aligned with the fuel inlet adapter. The positioning system may be used with a conductive reference marker located at a known position from the fuel inlet adapter and preferably includes at least three sense inductors located at known positions with respect to the pump assembly, and a controller for moving the lateral movement device so that the nozzle is substantially aligned with the fuel inlet adapter. The variation in distance between the reference marker and the sense inductors preferably causes inductance variation in each sense inductor which the controller uses to calculate the position of the fuel inlet adapter relative to the nozzle. In a certain most preferred embodiment, the controller can continue to calculate the position of the fuel inlet adapter relative to the nozzle as the nozzle is moved upwardly or downwardly (in the Z direction) and laterally (in the X and Y directions).  
           [0036]    In an alternate description of the pump assembly, the frame supporting the fuel nozzle is positioned below the vehicle before fueling and is upwardly moveable to provide operative connection between the nozzle and the fuel entrance. Such a fueling assembly preferably includes a nozzle sheath having a sheath cavity in which the nozzle is positioned before fueling, and a collar connected with respect to the nozzle sheath and formed for mating engagement with the fuel inlet adapter. As above, the nozzle sheath is compressible such that when upward movement of the frame causes the collar to contact the fuel inlet adapter, the sheath stops moving upward and the nozzle continues to move upward out of the sheath cavity and into the inlet cavity to provide operative connection with the fuel hose.  
           [0037]    The pump assembly preferably further includes a pan for preventing fuel spills which extends outwardly from the nozzle sheath and has a drain opening, a flexible drain hose connected with respect to the drain opening which extends to a container to collect spilled fuel and debris, and a shroud for preventing fuel spills which is connected with respect to the pan and has a shroud recess in which the collar is positioned. The preferred pump assembly also includes a fuel pipe which is operatively connected to the nozzle to provide the nozzle with fuel. It is preferred that a vacuum blower be operatively attached to the fuel pipe to enable removal of fuel vapor from the fuel tank during fueling.  
           [0038]    In another description of the invention, the vehicle fuel tank inlet assembly is for use with a fuel tank having a fuel line leading to a fueling position which allows manual fueling. The inlet assembly delivers fuel to the fuel tank during automatic fueling and comprises a flexible fuel conduit with a fuel entrance and a fuel exit for operative connection with the fuel tank, a first unidirectional valve positioned between the fuel tank and the fuel entrance to prevent fuel from moving toward the fuel entrance, a second unidirectional valve positioned between the fuel tank and the fueling position to prevent fuel from moving toward the fueling position, and a fuel inlet adapter with an inlet cavity for receiving a fuel nozzle during automatic fueling connected with respect to the fuel entrance and mounted to the vehicle. The first and second unidirectional valves are preferably spring loaded.  
           [0039]    The inlet assembly preferably includes flexible sealing doors which extend into the inlet cavity and provide for sealing between the adapter and the nozzle during fueling. The adapter may also include a slide cover for preventing debris from entering the cavity and which opens upon contact with the fuel nozzle.  
           [0040]    The fuel inlet adapter is also preferably mounted at a position lateral to the tank, i.e., not directly below or above the tank. The conduit preferably travels laterally from the inlet adapter to the tank.  
           [0041]    The inlet assembly preferably includes a conductive reference marker at a known location relative to the adapter which enables a positioning system to calculate the position of the fuel inlet adapter. Such a conductive reference marker preferably allows use of triangulation by sense inductors to calculate the adapter position and does not require a separate power source such as a battery.  
           [0042]    In another description of the invention, the fuel pump assembly is provided for automatic fueling of a fuel tank in a vehicle which has a conductive reference marker located at a known position relative to the fuel tank. The pump assembly preferably includes a fuel nozzle defining a passageway for fuel for operative connection with the fuel tank and a positioning system for moving the fuel nozzle into operative connection with the fuel tank during automatic fueling. The positioning system includes a lateral movement device operatively supporting the nozzle, at least three sense inductors for locating the conductive reference marker which are located at known positions relative to the nozzle and which experience inductance variation when the distance between the marker and the respective sense inductor changes, and a controller for moving the lateral movement device in response to inductance variation so that the nozzle is substantially aligned for operative connection to the fuel tank.  
           [0043]    The controller preferably uses the inductance variation to calculate the position of the fuel tank and can calculate the position of the fuel tank relative to the nozzle as the nozzle is moved upwardly and laterally. The preferred lateral movement device comprises slide plates which can be moved in a first direction and in a second direction substantially perpendicular to the first direction, i.e., in the X and Y directions.  
           [0044]    The pump assembly preferably further comprises a frame which supports the fuel nozzle, is positioned below the vehicle before fueling and is upwardly moveable to provide operative connection between the nozzle and the fuel tank. The frame is preferably connected with respect to at least one riser which powers upward and downward movement of the frame. The frame is also preferably connected with respect to the lateral movement device which moves the frame in the X and Y directions so that the nozzle is substantially aligned with the fuel tank.  
           [0045]    During operation of the invention, when a vehicle is driven into approximate position above the pump assembly, the positioning system begins use of the sense inductors to locate the reference marker. Immediately, the riser and lateral movement device move the nozzle toward the inlet adapter. As the nozzle moves toward the inlet adapter, the sense inductors continue to hone in on the adapter and the controller continues to calculate the position of the adapter and operate the riser and lateral movement device. Because the positioning system utilizes the inductance variations in the sense inductors to guide the pump assembly, the vehicle need not be equipped with any device requiring power to communicate the inlet adapter&#39;s position. Instead, the reference marker simply affects the inductance in the sense inductors.  
           [0046]    In a certain preferred embodiment the fuel tank has a fuel entrance and further includes a nozzle sheath having a sheath cavity in which the nozzle is positioned before fueling, and a collar for mating engagement with the fuel entrance and which is connected with respect to the nozzle sheath. The preferred nozzle sheath is compressible such that when upward movement of the frame causes the collar to contact the fuel entrance, the sheath stops moving upward and the nozzle continues to move upward out of the sheath cavity.  
           [0047]    In another preferred embodiment the pump assembly includes a pan for preventing fuel spills which extends outwardly from the nozzle sheath and has a drain opening, a flexible drain hose connected with respect to the drain opening and extending to a container, and a shroud for preventing fuel spills which is connected with respect to the pan and has a shroud recess in which the collar is positioned.  
           [0048]    The preferred pump assembly further includes a fuel pipe which is operatively connected to the nozzle so that fuel passes from the fuel pipe through the nozzle. The preferred pump assembly may include a vacuum blower operatively attached to the fuel pipe for removing fuel vapor from the fuel tank during fueling. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0049]    The drawings illustrate preferred embodiments which include the above-noted characteristics and features of the invention. The invention will be readily understood from the descriptions and drawings. In the drawings:  
         [0050]    [0050]FIG. 1 is a cross sectional view (not to scale) of an automatic vehicle fueling assembly in accordance with this invention before fueling.  
         [0051]    [0051]FIG. 2 is a cross sectional view (not to scale) of an automatic vehicle fueling assembly in accordance with this invention during the upward movement of the pump assembly, specifically when the collar contacts the fuel entrance.  
         [0052]    [0052]FIG. 3 is a cross sectional view (not to scale) of an automatic vehicle fueling assembly in accordance with this invention when the pump assembly and fuel tank inlet assembly are engaged for fueling.  
         [0053]    [0053]FIG. 4 is a larger cross sectional view (not to scale) of the fuel tank inlet assembly.  
         [0054]    [0054]FIG. 5 is a larger cross sectional view (not to scale) of the pump assembly.  
         [0055]    [0055]FIG. 6 is a larger cross sectional view (not to scale) of an alternate embodiment of the fuel tank inlet assembly.  
         [0056]    [0056]FIG. 7 is a schematic plan view of the automatic vehicle fueling assembly with the ground surface in phantom and including the positioning system in accordance with this invention.  
         [0057]    [0057]FIG. 8 is a plan view of the bottom side of the sealing doors on the fuel inlet adapter.  
         [0058]    [0058]FIG. 9 is a cross section view of the fuel inlet adapter showing the operative details of the slide cover. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0059]    [0059]FIGS. 1, 2 and  3  show the automatic vehicle fueling assembly  2  before fueling, during upward movement of the pump assembly  60  toward fuel tank inlet assembly  30  including engagement of the fuel entrance  33  by the collar  70 , and during fueling, respectively.  
         [0060]    Fuel tank inlet assembly  30  is shown in greater detail in FIG. 4. Inlet assembly  30  provides for automatic fueling of a vehicle with a standard fuel tank  10  and standard fuel line  20  which leads to a position for manual fueling (typically on the side of a vehicle). Inlet assembly  30  includes fuel conduit  32  which has a fuel entrance  33  and fuel exit  34 . Fuel exit  34  is operatively connected to fuel tank  10 . Fuel conduit  32  is preferably comprised of a flexible fuel hose  46 .  
         [0061]    Flexible fuel hose  46  has a first end  47  and a second end  48 . Second end  48  of fuel hose  46  is connected to first opening  41  of fitting  40 . Second opening  42  of fitting  40  is connected to fuel line  20 . Third opening  43  of fitting  40  is connected to fuel tank  10 . Although fitting  40  is shown as having three openings  41 , 42 , 43 , it is acknowledged that fitting  40  may include more than three openings if needed.  
         [0062]    Valve  44  is positioned in fitting  40  to prevent fuel from traveling from fitting  40  toward first end  47  of hose  46 . Valve  45  is positioned in fitting to prevent fuel from traveling from fitting  40  toward the position for manual fueling. Each of valves  44 , 45  is unidirectional, i.e., allowing fuel flow in only one direction, and is preferably spring loaded. Each of valves  44 , 45  allows vapor to escape from tank  10  as is necessary during fueling.  
         [0063]    First end  47  of hose  46  is shown connected to fuel inlet adapter  50 . Inlet adapter  50  defines inlet cavity  52  which received nozzle  62  during fueling. Inlet adapter  50  also includes sealing doors  53  which provide for sealing engagement between nozzle  62  and inlet adapter  50  during fueling. Sealing doors  53  are preferably rubber and are shown in more detail in FIG. 8. Inlet adapter  50  also includes slide cover  54  which covers inlet cavity  52 . Slide cover  54  opens when contacted by nozzle  62  and is shown in greater detail in FIG. 9.  
         [0064]    Inlet adapter  50  is mounted to the underside of the vehicle by vehicle mount  51 . Also positioned on the underside of vehicle is conductive reference marker  55 . Marker  55  is shown as an annular piece attached to adapter  50 ; however, marker  55  can be anywhere as long as marker  55  is placed at a known position relative to inlet adapter  50 .  
         [0065]    Pump assembly  60  is shown in greater detail in FIG. 5. Pump assembly  60  provides for delivery of fuel through nozzle  62  to inlet adapter  50 . Nozzle  62  defines fuel passageway  63 . Nozzle  62  is operatively connected to fuel pipe  82  so that fuel passes from fuel regulator  79  to inlet adapter  50 . As is known in the art, fuel passes along the inner circumference of fuel pipe  82  and nozzle  62  while vapor moves in the opposite direction in the center of pipe  82  and nozzle  62 . This can be seen at upper end  61  of nozzle  60  where vapor is able to pass through vapor hole  68 , while liquid fuel is able to pass though fuel port  69 . As shown in FIG. 1, vacuum blower  84  is connected to and removes vapor from fuel pipe  82 .  
         [0066]    Nozzle  62  is supported by frame  64 . Frame  64  is connected to risers  81  which provide for upward and downward movement of frame  64  and, thus, nozzle  62 . Risers  81  are connected to lateral movement device  80  which is preferably a slide plate or slide plates capable of movement in the X and Y directions. By controlling the movement of risers  81  and lateral movement device  80 , nozzle  62  can be positioned for connection with fuel conduit  32 .  
         [0067]    Nozzle sheath  65  defines sheath cavity  66  in which nozzle  62  is located prior to fueling. Nozzle sheath  65  is preferably cylindrical, is connected to frame  64  and collar  70  and is compressible such that during upward movement by risers  81 , upon contact by collar  70  with fuel entrance  32  or inlet adapter  50  the top end of sheath  65  reaches a fixed height while the bottom end of sheath  65  continues to move upward. Compression of sheath  65  is preferably provided by use of compression springs  67  which interconnect sheath  65  with frame  64  and collar  70 . While the top end of sheath  65  remains at a fixed height, nozzle  62  continues to move upward, substantially out of sheath cavity  66  to connect with inlet adapter  50 .  
         [0068]    Spanning across sheath cavity  66  are seals  72  which prevent debris from entering cavity  66 . Seals  72  are preferably rubber and are slotted to allow movement of nozzle  62  therethrough. Pan  73  extends outwardly from collar  70  and preferably terminates in a raised edge to catch splattered fuel, or water or ice from the underside of the vehicle. Pan  73  includes a drain opening  76  and flexible and extendable drain hose  77  is connected thereto and directs fluid into container  78  so that the ground is not contaminated. Extending upwardly from pan  73  is shroud  74  which acts to collect splashed fuel, water and ice. Shroud  74  defines shroud recess  75  in which collar  70  is positioned. Shroud  74  is preferably corrugated rubber which is flexible and can contact the underside of the vehicle without causing damage.  
         [0069]    Collar  70  may also have a high pressure air valve  79  extending into shroud recess  75 . Air valve  79  may be used to clean or knock debris from fuel entrance  33  or adapter inlet  50  before fueling so that such debris is not carried by the fuel to tank  10 .  
         [0070]    As stated above, FIGS. 1, 2 and  3  show the automatic vehicle fueling assembly  2  before fueling, during upward movement of the pump assembly  60  toward fuel tank inlet assembly  30  including engagement of the fuel entrance  33  by the collar  70 , and during fueling, respectively.  
         [0071]    As can be seen in FIG. 1, pump assembly  60  is in its normal pre-fueling state with sheath  65  held between springs  67 . In FIG. 2, pump assembly remains in such pre-fueling state, but collar  70  has contacted and engaged fuel entrance  33  (while risers  81  are illustrated as having the same height as in FIG. 1, risers  81  would have extended to move collar  70  into contact with fuel entrance  33  from the non-contact position in FIG. 1). In FIG. 3, sheath  65  is shown compressed, with nozzle  62  extending out of sheath cavity  63  and into inlet cavity  52 . As can be seen, seals  72  and sealing doors  53  engage nozzle  62  and provide a seal such that fuel does not escape. Risers  81  are extending upwardly while drain hose  77  and fuel pipe  82  have extended.  
         [0072]    [0072]FIG. 6 depicts an alternate embodiment to the fuel tank inlet assembly shown in FIG. 4. In the alternate embodiment gas tank  10  includes two separate fuel ports  12 , 14 . Fuel exit  34  of fuel conduit  32  (or second end  48  of flexible fuel hose  46 ) connects to first fuel port  12  while fuel line  20  connects to second fuel port  14 . Unidirectional first valve  44  and second valve  45  must be positioned in fuel conduit  32  and fuel line  20  to prevent fuel from flowing from tank  10  to fuel entrance  33  (or first end  47  of flexible fuel hose  46 ). Flexible hose  46  allows fuel inlet adapter  50  to be positioned anywhere on the underside of the vehicle and provides that any force applied to inlet adapter  50  is not transferred to tank  10 , thereby preventing damage to tank  10 .  
         [0073]    [0073]FIG. 7 is a schematic view of the invention including positioning system  100 . As stated above, conductive reference marker  55  is placed at a fixed position with a known position relative to fuel entrance  33 . As shown, reference marker  55  is an annular piece attached to adapter  50 . At least three sense inductors  90  are placed around pump assembly  40  at a known position relative to lateral movement device  80 . Sense inductors  90  are shown embedded in the ground surrounding pump assembly  40  (which is shown beneath the ground before it is moved into fueling position). Distances D1, D2, D3 between sense inductors  90  and reference marker  55  are measured via inductance variation in each sense inductor. Measurement continues as pump assembly  60  is moved upwardly. A controller compares the inductance variation in for each sense inductor and uses triangulation calculations to determine the exact position of reference marker  55 , and thus, fuel entrance  33 , relative to pump assembly  30 . In this manner, as soon as a vehicle is positioned at a fueling station, the pump assembly can begin upward movement while determining the position of fuel entrance  33 . Upon determination of this position, controller continues to operate lateral movement device  80  and risers  81  to position nozzle  62  for engagement with fuel tank inlet assembly  30 .  
         [0074]    Although shown attached to fuel inlet adapter  50 , reference marker  55  could be placed at any position allowing for inductance variation in sense inductors  90  as long as the position has a known position relative to fuel entrance  33 .  
         [0075]    [0075]FIG. 8 shows the arrangement of sealing doors  53  covering inlet cavity  52 . FIG. 9 shows the design of slide cover  54 . Slide cover  54  is comprised of two semicircular pieces which are sized to cover fuel entrance  33 . Bracket  57  is fixed to adapter  50  and holds the semicircular pieces between two sets of springs  56  which are biased to force slide cover shut. Each semicircular piece includes a notch  58  at its straight edge. As nozzle  62  moves upward into cover  54 , it moves into notch  58  and forces slide cover  54  open. When nozzle  62  is removed from inlet cavity  52 , springs  56  force slide cover  54  shut.  
         [0076]    While the principles of this invention have been described in connection with specific embodiments, it should be understood clearly that these descriptions are made only by way of example and are not intended to limit the scope of the invention.