Abstract:
In at least some implementations, a fuel tank includes a tank body defining a chamber adapted to receive liquid fuel therein, a reinforcement for the tank body to permit the pressure within the chamber to exceed the vapor pressure of a fuel to be received within the chamber, and an inlet to the tank body through which fuel is added to the chamber. The inlet is configured to mate with a refueling nozzle through which fuel is added to the chamber to permit refueling the tank and maintaining the pressure in the chamber above atmospheric pressure.

Description:
REFERENCE TO CO-PENDING APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application Nos. 61/861,187 filed Aug. 1, 2013 and 61/863,483 filed Aug. 8, 2013, which are incorporated herein by reference in their entirety. 
     
    
     TECHNICAL FIELD 
       [0002]    The present disclosure relates generally to a vehicle fuel tank. 
       BACKGROUND 
       [0003]    Many vehicles include fuel tanks that hold fuel that is eventually supplied to a prime mover like an internal combustion engine to support operation of the engine. In addition to holding fuel, fuel tanks commonly house components within their interiors such as pumps, valves, and the like. And the fuel tanks may be associated with large capacity vapor handling systems include large vapor canisters to manage the fuel vapor that is generated within the tank, which is maintained at or very near atmospheric pressure, and inhibit fuel vapor from escaping to the atmosphere. These larger vapor handling systems add weight and cost to a vehicle. 
       SUMMARY 
       [0004]    In at least some implementations, a fuel tank includes a tank body defining a chamber adapted to receive liquid fuel therein, a reinforcement for the tank body to permit the pressure within the chamber to exceed the vapor pressure of a fuel to be received within the chamber, and an inlet to the tank body through which fuel is added to the chamber. The inlet is configured to mate with a refueling nozzle through which fuel is added to the chamber to permit refueling the tank and maintaining the pressure in the chamber above atmospheric pressure. 
         [0005]    In at least some implementations, a fuel tank includes a tank body defining a chamber adapted to receive liquid fuel therein, a valve to limit fluid flow from the chamber and permit the pressure within the chamber to exceed the vapor pressure of a fuel to be received within the chamber, and an inlet to the tank body through which fuel is added to the chamber. The inlet is configured to mate with a refueling nozzle through which fuel is added to the chamber to permit refueling the tank and maintaining the pressure in the chamber above atmospheric pressure. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    The following detailed description of preferred embodiments and best mode will be set forth with reference to the accompanying drawings, in which: 
           [0007]      FIG. 1  is a diagrammatic view of a fuel tank system; 
           [0008]      FIG. 2  is a fragmentary diagrammatic view of a portion of an alternate fuel tank system; 
           [0009]      FIG. 3  is a diagrammatic view of a fuel tank system having a vapor canister; 
           [0010]      FIG. 4  is a diagrammatic view of another fuel tank system; and 
           [0011]      FIG. 5  is a diagrammatic view of a fuel tank system including an auxiliary fluid container. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0012]    Referring in more detail to the drawings,  FIG. 1  illustrates a vehicle fuel tank  10  designed to contain a volume of fuel to support operation of the vehicle&#39;s engine. The fuel tank  10  may have a tank body  12  defining an interior chamber  14  in which fuel is received and a fill pipe  16  through which fuel is admitted into the chamber  14 . If desired, an overpressure relief valve  18  that opens only when the pressure in the fuel tank  10  is above a threshold level may also be provided. A fuel pump  20  may be located inside the fuel tank  10 , or outside of the fuel tank if desired. The fuel pump  20  may take in fuel from the fuel tank chamber  14  and deliver it under pressure to fuel system components (e.g. a fuel rail and fuel injectors) downstream of the fuel tank. The fuel pump  20  may be of conventional construction and arrangement and will not be discussed further. The output from the fuel pump  20  may be provided through a conduit  22  that passes through an opening  24  of the fuel tank, preferably in the same area as the relief valve  18  to limit the number of openings through the fuel tank. 
         [0013]    The fuel tank  10  may be constructed to contain liquid fuel at a pressure higher than conventional passenger vehicle fuel tank systems. In at least certain embodiments, the fuel tank  10  may contain fuel at a pressure above the vapor pressure of the fuel to prevent formation of fuel vapor in the fuel tank, for example, at a pressure higher than 35 kPa and up to 150 kPa or a pressure that can naturally occur in a fuel system under the range of environmental conditions of use. This will reduce or eliminate the need to provide fuel vapor handling systems, such as carbon canisters and related conduits and valves. While the system could be externally pressurized, it is not necessary to do so and the pressure generated or realized in the tank may occur naturally under the range of environmental conditions the vehicle may experience. 
         [0014]    To do this, the fill pipe  16  may be selectively closed, such as by one or more valves, to prevent loss of pressure upon filling the tank. And the refueling nozzles used to provide fuel into the fuel tank may also be configured to seal with the fill pipe  16  and provide a pressurized supply of fuel to the tank  10 . To this end, the fill pipe  16  may include a head  26  that includes features complementary to the refueling nozzle to receive and adequately seal against the refueling nozzle. The relatively high pressure at which the refueling operation occurs will also reduce or prevent formation of fuel vapor, thereby reducing emissions normally associated with refueling and reducing or eliminating the need for a carbon canister or other vapor handling components. 
         [0015]    The tank body  12  itself may be formed from any suitable material including, for example, metals and/or plastics. To bear the internal pressures discussed above, various support structures may be incorporated into and/or about the exterior of the fuel tank especially when the tank is formed from plastics. In that regard, the tank may be formed from any number of layers of plastic material and may include structure and vapor barrier layers as is known in the art. 
         [0016]    Also, the tank may be formed by any suitable method including, but not limited to, blow molding, injection molding, vacuum forming and the like. In one implementation, the tank is formed by an extrusion blow molding process. In that process, a molten parison of plastic material is extruded and provided into a blow mold. The parison may be pre-blown by the introduction of a pressurized gas into a closed interior of the parison to initially expand the parison outwardly within a cavity of the blow mold. Thereafter, the parison may be severed, torn or otherwise manipulated to permit access to the interior of the parison. In that regard, the parison may be completely separated into two or more distinct and separate portions, or only partially opened/breached to expose the interior. One or more support structures  28  or other components may then be placed within the interior of the parison before the parison interior is closed and final molding of the tank performed. Possible molding process and apparatus are disclosed in U.S. patent application Ser. No. 12/491,964 filed Jun. 25, 2009, the disclosure of which is incorporated herein by reference in its entirety. Of course, other molding process and apparatus may be used. The fuel pump and pressure relief valve, if any, could also be incorporated onto/into the parison during the molding process, such as but not limited to when the parison interior is accessible. 
         [0017]    As shown in  FIG. 1 , the support structures  28  may include both internal structures (such as, but not limited to, posts, walls, tethers, beams) and external structures  29  (such as, but not limited to, belts, bands, sleeves, plates, walls) secured to and/or about the exterior of the tank either or both during or after the tank is formed. While shown as at least somewhat discrete components, the support structures could include one or more shells or other layers of material that define a complete enclosure in which an inner tank or shell is received, such as is disclosed in U.S. patent application Ser. No. 13/038,936 filed Mar. 2, 2011, the disclosure of which is incorporated herein by reference in its entirety. Of course, the outer layer or shell need not define a complete enclosure, but could if desired. The inner shell or tank would define the interior chamber in which the fuel is stored. Alternatively, the interior shell or tank need not define an imperforate or complete enclosure and the liquid fuel could instead be ultimately retained by an outer shell or tank. 
         [0018]    The relatively high pressure within the fuel tank  10  significantly inhibits or prevents formation of fuel vapor such that vent valves, fuel vapor/carbon canisters and related conduits and connectors are not needed. This greatly simplifies the fuel delivery system, and reduces the number of system components and the cost. Without vent and rollover type valves, and without a vapor canister, there is no need to provide vapor canister purge components and control systems. And there is no possibility of liquid fuel flowing into a vapor canister, so there is no need for baffles and other liquid shields or valves to allow vapor flow but prevent liquid flow to the canister. The system may be lighter (possible improved vehicle fuel economy), uses less material and is easier to recycle. 
         [0019]      FIG. 2  illustrates a vapor conduit or vent line  30  associated with the fill pipe  16 . The vent line  30  may be coupled to a complementary feature on a refueling nozzle to provide a gaseous matter flow path from the tank to the refueling nozzle during refueling of the fuel tank. The flow path could be separate from the liquid flow path and, in at least some implementations, may only be opened upon secure and sealed connection to a refueling nozzle. The refueling nozzle, or a component downstream of the nozzle, may be equipped with a system for handling the fuel vapor and preventing undue emissions to the atmosphere. This enables controlled venting of the tank and reduces or eliminates emissions during refueling. 
         [0020]    Because refueling nozzles are not currently equipped with components to provide a sealed and secure connection to a fill pipe as described above,  FIG. 3  illustrates an embodiment designed for use with existing refueling nozzle technology. In  FIG. 3 , the fuel tank  40  may be constructed as described above with regard to  FIG. 1 . A fill level vent valve  42  may be provided in or downstream of the fuel tank  40 . As is known in the art, the fill level vent valve  42  may have a valve element that is normally open to permit fuel vapor to leave the fuel tank therethrough and is closed by liquid fuel to prevent liquid fuel flow through the valve. Therefore, when the fuel tank  40  is being refilled, a maximum desired fuel level within the tank can be controlled by the vent valve  42  which closes when the fuel actuates its valve element to prevent further venting of the fuel tank  40 . When the vent valve  42  is closed, the addition of further fuel to the tank  40  will increase the pressure within the tank and cause fuel to backup within the fill pipe  44  and actuate a shut-off feature of the refueling nozzle from which fuel is provided. 
         [0021]    Downstream of the vent valve  42 , a secondary valve  46  may be provided and downstream from the secondary valve  46  a vapor canister  48  may be provided. The secondary valve  46  may be open during the refueling process to permit fuel vapor to flow from the fuel tank to the vapor canister  48 , as is known in the art. The secondary valve  46  may be closed at other times to prevent gaseous flow from the tank  40  and thereby provide a sealed or closed tank in which a desired pressure may be maintained. In one of several possible forms, the secondary valve  46  is actuated by a solenoid. Also in one form, an overpressure relief function may be incorporated into the secondary valve  46 , or a separate valve may be provided in a bypass flow path between the tank  40  and vapor canister  48 , or otherwise from the tank. This prevents the pressure within the tank  40  from exceeding a predetermined maximum pressure. While shown as being physically located downstream of the vent valve  42 , the secondary valve  46  could be incorporated in a common housing or structure with the vent valve  42 , and/or maybe otherwise carried by the tank  40 , and may be downstream of the vent valve in the flow path toward the vapor canister  48 . Because the secondary valve  46  is closed at times other than refueling, a roll-over valve is not needed and the fill limit valve  42  can be designed more simply to control the maximum fuel level in the fuel tank  40 . 
         [0022]    The vapor canister  48  may be small in size and capacity compared to conventional canisters. For example, the larger vapor canisters typically used in U.S. vehicles may be replaced with smaller canisters typically used in European vehicles. And/or the smaller canister may be sized for receiving vapors only during refilling and without also receiving diurnal emission of vapor. This is possible because the vapor canister only receives gasses during the refueling event and not during other operation of the vehicle. Further, because the flow path to the vapor canister  48  is closed at times other than refueling (because the secondary valve  46  is closed), the possibility of liquid flowing to the vapor canister  48  is reduced and likely eliminated such that valves, baffles and other devices are not needed to prevent liquid fuel flow to the canister. Further, complex valve arrangements and control schemes are not needed to manage vapor and liquid flow. Instead, the vapor canister may simply have a port  47  through which vapors are purged to the vehicle engine (for example, without limitation), and a clean air port  49  to the atmosphere. 
         [0023]      FIG. 4  illustrates another implementation of a fuel tank system that also includes a vapor canister  50  and a valve  52  upstream of the vapor canister. The valve  52  may be solenoid actuated or of other design, and is opened before a refueling event to depressurize the fuel tank  54 . An overpressure relief valve may be incorporated into the valve  52  or otherwise provided, as noted above. A fill limit nipple  56  may be provided at the tank  54  and include a conduit  58  associated with the fill pipe  60 . The conduit  58  may communicate vapor with the refueling nozzle or other component during a refueling event, and a signal may be provided through the conduit  58  to the refueling nozzle when the fuel tank  54  is full (i.e. a maximum desired fuel level is achieved) to terminate the refueling event and prevent overfilling the tank  54 . The refueling nozzle may be constructed and arranged to receive the signal and shut-off the flow of fuel into the tank  54  in response. Such fill limit nipple  56  and fuel shut off systems are known and used, for example, in Europe. As above, the valve  52  may be closed except during a refueling event and so no roll over valve is needed. To further inhibit or protect against liquid fuel flowing to the vapor canister, the valve  52  could be opened only before the refueling event and closed during the refueling event. And the system can be formed with relatively few components and provide simpler integration of a smaller vapor canister. Further, the system can provide an increased pressure within the fuel tank at times other than refueling, and can depressurize the tank prior to refueling. 
         [0024]    Accordingly, the fuel tank systems may be closed during normal operation in that no fluid flow into or out of the fuel tank system is permitted. A higher pressure may be maintained with the fuel tank systems at least at times other than during a refueling event. This may reduce or prevent the formation of fuel vapor and reduce the size and cost of any vapor handling components, if any such components are needed. Venting of the tank may be permitted during a refueling event and a vapor canister may be included in the venting scheme, if desired. The fuel tank may be reinforced during the manufacturing process or thereafter, to accommodate the increased internal pressure. 
         [0025]      FIG. 5  illustrates a fuel system  80  like that shown in  FIG. 1  and including an auxiliary fluid container  82 . Many of the same reference numbers used in  FIG. 1  have been used in  FIG. 5  for ease of description. The container  82  could, but need not, include any charcoal or other vapor handling material and may instead by a simple enclosure defining a chamber in which vapor/gaseous matter may be received. The container  82  may be formed of any suitable material and could be formed in one piece with the main fuel tank  10  or separately, and may be carried by or remotely from the fuel tank. The container  82  may be communicated with the fuel tank  10  by a suitable passage, which is shown in  FIG. 5  as a conduit  84  extending between the tank  10  and container  82 . The conduit  84  may provide two-way flow of gaseous matter between the fuel tank and the fluid container (especially if no vapor absorbing material is provided in the container, liquid carryover or flow into the container may not present any problem). To control the flow between the fuel tank  10  and the fluid container  82 , a valve  86  may be provided. The valve may be opened to permit flow therethrough and between the tank  10  and container  82  and closed to prevent or at least substantially inhibit such flow. The valve  86  may be solenoid driven or otherwise controlled. Such a fluid container  82  may be used in combination with or instead of a vapor canister, and may be used in other fuel systems than that shown in  FIG. 1 . 
         [0026]    Before and during a refueling event, vapor may be transferred from the tank  10  to the fluid container  82 . This may be accomplished with a pump  88 , and/or by a pressure differential between the tank and container. After a refueling event, the valve  86  may be opened to release the vapor from the container  82  back into the tank  10 . This provides a way to manage vapor during a refueling event and will permit the tank system  80  to remain closed while maintaining a minimal pressure to, for example, forward fuel to a high pressure pump. In at least some implementations, the vapor in the fluid container  82  may condense into liquid (e.g. from a pressure within the container that is above the evaporation level of the fuel) and the liquid may then be transferred back into the tank  10 . Here, instead of absorbing vapor as in a charcoal based vapor canister, the vapor is liquefied and returned to the tank. 
         [0027]    While the forms of the invention herein disclosed constitute presently preferred embodiments, many others are possible. It is not intended herein to mention all the possible equivalent forms or ramifications of the invention. It is understood that the terms used herein are merely descriptive, rather than limiting, and that various changes may be made without departing from the spirit or scope of the invention.