Abstract:
A secondary fuel pump assembly for a fuel tank in a vehicle includes a reservoir adapted to be disposed in the fuel tank having a top defining an overflow fuel level of the reservoir. The secondary fuel pump assembly also includes a conduit conducting return fuel from an engine of the vehicle to the reservoir and a jet pump having a discharge outlet in the reservoir and an inlet operatively connected to the conduit. The secondary fuel pump assembly includes an overflow fuel member defining a flow path for overflow of fuel in the reservoir and a guide member extending into the overflow fuel member and having at least one aperture extending therethough. The secondary fuel pump assembly further includes a guide disposed over the guide member and movable relative thereto to open and close the at least one aperture and a float connected to the guide to move the guide as a fuel level rises and falls in the reservoir.

Description:
TECHNICAL FIELD 
     The present invention relates generally to fuel tanks for vehicles and, more particularly, to a secondary fuel pump assembly for a fuel tank of a vehicle. 
     BACKGROUND OF THE INVENTION 
     It is known to provide a fuel tank for a vehicle to hold fuel to be used by an engine of the vehicle. In some vehicles, the fuel tank includes a fuel pump module disposed therein with a removable cover sealed to the top of the fuel tank having an electrical connector and a fuel line outlet connector. The fuel pump module includes a fuel reservoir, an electrical fuel pump disposed in the reservoir with an inlet (not shown) at a bottom thereof and a secondary pump used to fill the reservoir to overfilling. This overfilling of the reservoir allows the generation of vapors due to the agitation of the fuel as well as the mixing of the hot fuel, being returned from an engine of the vehicle, with bulk fuel. 
     An example of a fuel pump module is disclosed in U.S. Pat. No. 5,218,942 to Coha et al. In this patent, the fuel pump module includes a fuel pump disposed in the reservoir, a low pressure conduit conducting hot return fuel back to the reservoir, a secondary pump disposed in the reservoir for pumping new fuel from the fuel tank into the reservoir, and a control which effects a recirculation mode of secondary pump operation when the new fuel level in the fuel tank is above a predetermined low level and a scavenge mode of secondary pump operation when the new fuel level in the reservoir is below the predetermined low level. The secondary pump includes a high-pressure jet pump having consistent flow and a float mechanism to switch the jet pump from drawing external fuel to the reservoir and vice versa. 
     Therefore, it is desirable to provide a new secondary fuel pump for a fuel tank in a vehicle. It is also desirable to provide a secondary fuel pump for a fuel tank in a vehicle that reduces vapor generation. It is further desirable to provide a secondary fuel pump for a fuel tank in a vehicle that has no moving or extra parts. 
     SUMMARY OF THE INVENTION 
     It is, therefore, one object of the present invention to provide a new secondary fuel pump assembly for a fuel tank in a vehicle. 
     It is another object of the present invention to provide a secondary fuel pump assembly for a fuel tank in a vehicle that reduces vapor generation. 
     To achieve the foregoing objects, the present invention is a secondary fuel pump assembly for a fuel tank in a vehicle including a reservoir adapted to be disposed in the fuel tank having a top defining an overflow fuel level of the reservoir. The secondary fuel pump assembly also includes a conduit conducting return fuel from an engine of the vehicle to the reservoir and a jet pump having a discharge outlet in the reservoir and an inlet operatively connected to the conduit. The secondary fuel pump assembly includes an overflow fuel member defining a flow path for overflow of fuel in the reservoir and a guide member extending into the overflow fuel member and having at least one aperture extending therethough. The secondary fuel pump assembly further includes a guide disposed over the guide member and movable relative thereto to open and close the at least one aperture and a float connected to the guide to move the guide as a fuel level rises and falls in the reservoir. 
     One advantage of the present invention is that a secondary fuel pump assembly is provided for a fuel tank in a vehicle. Another advantage of the present invention is that the secondary fuel pump assembly reduces vapor generation by allowing the preferential use of “hot” fuel, returned from the engine or fuel which has been by-passed by the fuel regulator if the fuel regulator is in the fuel pump module or in close proximity to the fuel pump module, on a preferential basis. Yet another advantage of the present invention is that the secondary fuel pump assembly integrates an additional tube into the reservoir, thereby requiring no extra parts. Still another advantage of the present invention is that the secondary fuel pump assembly is lower in cost, simpler and improves quality over existing designs. 
     Other objects, features and advantages of the present invention will be readily appreciated, as the same becomes better understood, after reading the subsequent description taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a fragmentary elevational view of a secondary fuel pump assembly, according to the present invention, illustrated in operational relationship with a fuel tank of a vehicle. 
     FIG. 2 is view similar to FIG. 1 illustrating the secondary fuel pump assembly in a second operational state. 
     FIG. 3 is a partial fragmentary view of another embodiment, according to the present invention, of the secondary fuel pump assembly of FIG.  1 . 
     FIG. 4 is a graph of temperature versus time for the secondary fuel pump assembly of FIG.  1 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to the drawings and in particular FIGS. 1 and 2, one embodiment of a secondary fuel pump assembly  10 , according to the present invention, is shown for a fuel tank, generally indicated at  12 , in a vehicle (not shown). The fuel tank  12  has an upper wall  14  and a lower wall  16 . The secondary fuel pump assembly  10  is disposed in the fuel tank  12  and has a removable cover  18  sealed by a seal ring  20  to the upper wall  14  of the fuel tank  12 . It should be appreciated that, except for the secondary fuel pump assembly  10 , the fuel tank  12  is conventional and known in the art. 
     The secondary fuel pump assembly  10  includes a fuel reservoir  22  to hold fuel disposed inside the fuel tank  12 . The fuel reservoir  22  has a bottom portion  23  and an annular side portion  24  extending generally perpendicularly from the bottom portion  23  to form a chamber  26 . The fuel reservoir  22  is generally bucket-shaped and open at a top end  28  thereof, which defines an overflow fuel level in the fuel reservoir  22 . It should be appreciated that the top end  28  is above the highest level of new fuel in the fuel tank  12  so that there is little or no in-and-out flow over the top. It should also be appreciated that the top end may be partially closed to minimize splash-over while still venting the interior of the fuel reservoir  22 . 
     The secondary fuel pump assembly  10  also includes a return fuel member  30  extending upwardly from the bottom portion  23  of the fuel reservoir  22 . The return fuel member  30  is tubular and has a generally circular cross-sectional shape. The return fuel member  30  has a passageway  31  extending axially therethrough. The return fuel member  30  has a cavity  32  in a bottom thereof and aperture  34  interconnecting the passageway  31  and the cavity  32 . The return fuel member  30  is integral and formed as one-piece with the fuel reservoir  22 . It should be appreciated that the return fuel member  30  extends into the chamber  26  of the fuel reservoir  22 . 
     The secondary fuel pump assembly  10  includes a jet pump member  36  extending upwardly from the bottom portion  23  of the fuel reservoir  22 . The jet pump member  36  is tubular and has a generally circular cross-sectional shape. The jet pump member  36  has a passageway  38  extending axially therethrough. The jet pump member  36  has a cavity  40  in a bottom thereof and aperture  42  interconnecting the passageway  38  and the cavity  40 . The jet pump member  36  is integral and formed as one-piece with the fuel reservoir  22 . It should be appreciated that the jet pump member  36  extends into the chamber  26  of the fuel reservoir  22 . 
     The secondary fuel pump assembly  10  also includes an overflow fuel member  44  extending upwardly from the bottom portion  23  of the fuel reservoir  22 . The overflow fuel member  44  has a cavity  46  and a pair of apertures  48  in the bottom thereof interconnecting the cavity  46  and the interior of the fuel tank  12 . The overflow fuel member  44  is integral and formed as one-piece with the fuel reservoir  22 . It should be appreciated that the overflow fuel member  44  extends into the chamber  26  of the fuel reservoir  22 . 
     The secondary fuel pump assembly  10  includes a guide member  50  extending upwardly from the bottom portion  23  of the fuel reservoir  22  and through the overflow fuel member  44 . The guide member  50  is tubular and has a generally circular cross-sectional shape. The guide member  50  has a passageway  52  extending axially therethrough. The guide member  50  is integral and formed as one-piece with the fuel reservoir  22 . It should be appreciated that the guide member  50  extends into the chamber  26  of the fuel reservoir  22 . 
     The secondary fuel pump assembly  10  also includes a guide  54  disposed about the guide member  50  and movable axially relative thereto. The guide  54  is tubular and has a generally circular cross-sectional shape. The guide  54  has a flange  56  extending radially from an upper end thereof and overlapping the upper end of the overflow fuel member  44 . The guide  54  also has a projection  58  extending downwardly perpendicularly from the flange  56  for a function to be described. The guide  54  is integral and formed as one-piece. It should be appreciated that the guide  54  is movable or slideable along the guide member  50 . 
     The secondary fuel pump assembly  10  further includes a float  60  connected to the guide  54 . The float  60  extends axially. The float  60  is generally cylindrical in shape with a generally circular cross-sectional shape. The float  60  has a cavity  62  extending axially inward to receive the projection  58  of the guide  54  and be secured thereto by conventional means such as heat stake or an interference fit. The float  60  is made of a material being less dense than the fuel such as such as polyurethane, or blow molded from acetyl or nylon. It should be appreciated that the float  60  may have any suitable shape. 
     The secondary fuel pump assembly  10  also includes a secondary or jet pump  62  cooperating with the jet pump member  36 . The jet pump  62  has a first projection  64  extending outwardly and disposed in the cavity  32  of the fuel return member  30 . The first projection  64  is generally tubular in shape with a generally circular cross-sectional shape. The first projection  64  has an aperture  66  extending therethrough. The jet pump  62  has a second projection  68  extending outwardly and spaced laterally from the first projection  64  and disposed in the cavity  40  of the jet pump member  36 . The second projection  68  is generally tubular in shape with a generally circular cross-sectional shape. The second projection  68  has an aperture  70  extending therethrough. The jet pump  62  has a cavity  72  communicating with the apertures  66  and  70  and having an open end  74 . The jet pump  62  has a plug  76  closing the open end  74  with a projection  78  securing the plug  76  to the first projection  64 . The jet pump  62  has an aperture  80  extending therethrough and communicating with the cavity  72 . 
     The secondary fuel pump assembly  10  also includes a conduit or hose  82  connected to one end of the fuel return member  30  and a fuel connector  84  extending through the cover  18 . It should be appreciated that the fuel connector  84  returns hot fuel to the secondary fuel pump assembly  10 . 
     In operation, the secondary fuel pump assembly  10  is illustrated in an assembled state in FIG. 1 in which the guide  54  and float  60  are near a bottom of the fuel reservoir  22  during a reservoir full of fuel condition. Hot fuel from the engine returns via the fuel connector  84  and hose  82  to the return fuel member  30 . Hot fuel flows through the passageway  31  and aperture  34  of the fuel return member  30  to the jet pump  62 . In the jet pump  62 , hot fuel flows through the aperture  66  in the first projection  64  to the cavity  72  and through the aperture  70  in the second projection  68  to the jet pump member  36 . Hot fuel flows through the passageway  38  of the jet pump member  36  and into the chamber  26  of the reservoir  22  to fill the reservoir  22 . As the fuel level rises in the fuel reservoir  22 , the float  60  also rises to elevate or move the guide  54  upward and opening the apertures  48  in the overflow fuel member  44  as illustrated in FIG.  2 . As a result, fuel is aspirated from the fuel reservoir  22  through the apertures  48  and into the interior of the fuel tank  12 . As the fuel level falls in the reservoir  22 , the float  60  also falls and lowers the guide  54  downward toward the bottom of the fuel reservoir  22  to close the apertures  48  in a reservoir empty condition. Fuel is recirculated within the fuel reservoir  22  when sufficient fuel is in the reservoir  22  to allow fuel to spill into the overflow fuel member  44 . Bulk fuel is drawn into the reservoir  22  only when fuel is not being returned through the overflow fuel member  44 . It should be appreciated that the “contained” feature allows the preferential use of “hot” fuel and vapor generation is minimized. It should be appreciated that fuel being returned from the engine or fuel being by-passed by a fuel regulator (not shown) has a variable flow to the low-pressure jet pump  62  as a result of the fuel being used by the engine. It should also be appreciated that the vacuum being generated by the jet pump  62  is continuously varying. 
     Referring to FIG. 3, another embodiment  110 , according to the present invention, of the secondary fuel pump assembly  10  is shown. Like parts of the secondary fuel pump assembly  10  have like reference numerals increased by one hundred (100). In this embodiment, the secondary fuel pump assembly  110  includes a disc strainer  190  disposed in the overflow fuel member  144  and about the guide member  150  at one longitudinal end. The disc strainer  190  is generally circular in shape. The disc strainer  190  allows fuel to pass and provides a capillary seal. The disc strainer  190  is made of a filtering material such as woven fabric. It should be appreciated that the operation of the secondary fuel pump assembly  110  is similar to the secondary fuel pump assembly  10 , except that the jet pump  162  preferentially draws from the fuel reservoir  122 . 
     Referring to FIG. 4, a graph  192  of temperature on a y-axis  194  and time on an x-axis  196  is shown for the secondary fuel pump assembly  10 . The graph  192  illustrates good separation in the temperatures of the bulk fuel and the reservoir fuel. 
     The present invention has been described in an illustrative manner. It is to be understood that the terminology, which has been used, is intended to be in the nature of words of description rather than of limitation. 
     Many modifications and variations of the present invention are possible in light of the above teachings. Therefore, within the scope of the appended claims, the present invention may be practiced other than as specifically described.