Abstract:
An evaporative emissions fuel system for a general-purpose engine includes a fuel tank with a valve assembly located within the fuel tank for guiding fuel vapor to a canister. The canister contains activated charcoal to treat the fuel vapor and guide the vapor to a carburetor which burns the fuel vapor and hydrocarbons. The valve assembly has a valve opening for receiving the fuel vapor and a float responsive to the fuel within the tank for sealing the valve opening when the fuel within the tank is at a feel level capable of entering the valve opening.

Description:
[0001]    This application claims the benefit of U.S. Provisional Patent Application 60/791,324 filed on Apr. 12, 2006, the entirety of which is incorporated herein by reference. This application includes material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent disclosure, as it appears in the Patent and Trademark Office files or records, bat otherwise reserves all copyright rights whatsoever. 
     
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to the field of fuel vapor emissions systems for engines and more particularly to a fuel tank assembly for controlling evaporative emissions. 
       BACKGROUND OF THE INVENTION 
       [0003]    Evaporative emissions systems and the use of carbon or charcoal canisters have been used in combination with automotive engines and fuel tanks. However, new regulations have propelled the need for evaporative emissions control systems for small utility engines. Typically, these small utility engines and their associated gas tank have confined locations and dimensions forcing most of the components and lines of an evaporative emissions system to be exposed. Such exposure is both unsightly and problematic as such valves, components and lines are subject to damage. 
         [0004]    A typical emission control system  100 , as seen in  FIG. 1A , for a small utility engine consists of a fuel tank  102  which stores a fuel  104 , such as gasoline, and mates with a sealed cap  108 . The fuel tank  102  contains fuel which during operation of the engine is fed through hue  118  to a carburetor  120 . The flow of fuel along line  118  may be controlled by a feel shutoff valve (not shown). Attached to the tank  102  is a valve  105 , such as a slant valve, which allows emission vapors to escape the tank  102 , as pressure in the tank  102  increases, to a charcoal canister  125  through line  107 . The charcoal, canister  125  receives and treats the evaporative emissions. Upon starting the utility engine, suction is created drawing outside air in through vent  122  and thus purging the charcoal of the accumulated hydrocarbons and pulling the evaporative emissions within the charcoal canister  125  through line  124  into carburetor  120  where the evaporative emissions and hydrocarbons can be burned. After the engine is shut off the charcoal canister  125  continues to receive and treat the evaporative emissions from tank  102  until the engine is started again and the evaporative emissions and hydrocarbons are purged from the canister  125 , drawn into and burned by carburetor  120 . 
         [0005]    As seen in  FIG. 1B , a generator  101  is depicted which incorporates a known evaporative emissions system which exposes the valve  105  and the evaporative emissions line  107  leading to charcoal canister  125 . On or near the top surface of the fuel tank  102  is an opening  110  for receiving a sealed cap. Additionally, valve  105  mates with fuel tank  102  at a position on a top surface of the fuel tank  102 . The valve  105  is exposed creating an unsightly appearance for industrial design as well as exposing the valve  1 . 05  to possible damage. Further, the evaporative emissions line  107  runs along the top, down the side and along the end of fuel tank  102  before traveling down, the frame  103  of she generator  101  before finally connecting to canister  125 . Both the valve  105  and line  107  are susceptible to damage and create an unsightly appearance. 
         [0006]    Therefore, what is needed is an evaporative emissions system which provides a compact, cost effective and easy to manufacture design while reducing the unsightly appearance and exposure of the evaporative emissions valve and lines. 
       SUMMARY OF INVENTION 
       [0007]    The present invention provides an evaporative emissions fuel system for a general-purpose engine which overcomes the obstacles described above by providing a system with a fuel tank, a canister which absorbs fuel vapor from the fuel tank, a carburetor communicating with the fuel vapor from the canister and communicating with the fuel from the fuel tank; a valve assembly located within the fuel tank for receiving the fuel vapor from within the fuel tank and communicating the fuel vapor to the canister; and the valve assembly comprising a valve opening for receiving fuel vapor and a float responsive to the fuel within the tank for sealing the valve opening when the fuel within the tank is at a fuel level capable of entering the valve opening. The valve opening may be located above a max fuel level of the fuel tank and below a top interior surface of the fuel tank. The Post may be attached to a sealing element which seals the valve opening. The evaporative emissions fuel system may also comprise a valve assembly brace attached to an interior surface of the tank and to the valve assembly. 
         [0008]    Another aspect of the present invention provides a fuel tank assembly for a general-purpose engine comprising; a closed fuel tank having an inlet to the interior of the tank, a fuel outlet, and a fuel vapor outlet; an unvented fuel cap receivable on the inlet for sealing the closed fuel tank; a valve assembly located within the fuel tank for receiving fuel vapor from inside the fuel tank and communicating the fuel vapor through the fuel vapor outlet to a canister which absorbs and treats fuel vapor; a carburetor communicating with the fuel vapor from the canister and communicating with the fuel from the fuel tank through the fuel outlet; and the valve assembly comprising a valve opening for receiving fuel vapor and a float responsive to the fuel within the tank for sealing the valve opening when the fuel within the tank is at a fuel level, capable of entering the valve opening. Further, the valve opening may be located above a max fuel level of the fuel tank and below a top interior surface of the fuel tank. The float may be attached to a sealing element which seals the valve opening. Additionally, a valve assembly brace may be attached to an interior surface of the tank and to the valve assembly. 
     
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0009]      FIG. 1A  is a schematic view of a known fuel tank and exposed evaporative emissions system; 
           [0010]      FIG. 1B  is a side elevation view of a generator incorporating a known and exposed evaporative emissions system; 
           [0011]      FIG. 2  is a schematic view of a fuel tank and evaporative emissions system of the present invention; 
           [0012]      FIG. 3  is a sectional side view of an evaporative emissions valve of the evaporative emissions system of the present invention; 
           [0013]      FIG. 4A  is a front view of an alternative evaporative emissions valve which could be incorporated in the evaporative emissions system of the present invention; 
           [0014]      FIG. 4B  is a side view of the alternative evaporative emissions valve depicted in  FIG. 4A ; and 
           [0015]      FIG. 5  is a front view of an alternative evaporative emissions valve which could be incorporated in the evaporative emissions system of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0016]    The system of the present invention will now be described in conjunction with  FIGS. 2-5 . The present invention provides an evaporative emissions system which overcomes the obstacles described above by providing an evaporative emissions system which integrates the evaporative emissions valve and all or portions of the emissions flow line within the internal chamber of the fuel tank. 
         [0017]    As seen in  FIG. 2 , the evaporative emissions system  200  of the present invention includes a gas tank  202  which is used to house or contain a fuel  204  such as gasoline. The fuel tank  202  mates with a fill cap  208  which seals the emissions vapors and fuel within the fuel tank  202 . The cap  208  mates with a cap mating structure  210  which is also used to support a fuel filter or screen  209 . Fuel exits the tank  202  from an exit location  214  such as a welded pipe fitting or threaded sealed fitting. A threaded sealed fitting  214  is depicted in  FIG. 2  which also includes a brass fitting  216  which connects the exit  214  to a fuel shutoff valve  212 . A fluid passage line  218  connects the fuel shutoff valve  212  to carburetor  220 , During engine (not shown) operation, fuel is drawn from tank  202  through the fuel shutoff valve  212  and line  218  to carburetor  220 . 
         [0018]    When the engine is not in operation, external temperatures on the fuel, tank  202  can cause an increase of the fuel  204  temperature within the tank  202  causing an increase in vapor pressure within the tank  202 . Historically, this increased vapor pressure was simply released through vent holes in the cap. However, new emissions regulations do not allow untreated vapor pressure to be released into the atmosphere. Therefore, the vapor emissions system of the present invention cheers the vapor pressure in the fuel, tank  202  through a charcoal treatment section or canister  225 . In the present invention, the vapor pressure is directed to a charcoal treatment canister or chamber  225  through a fuel tank valve assembly  230 . The canister  225  typically uses activated carbon to treat the fuel vapor by removing the hydrocarbons. Once the engine is started the hydrocarbons from within the canister  225  are pulled into the carburetor  220  and burned. 
         [0019]    The fuel tank emissions valve assembly  230  is located inside the tank and includes a top portion  232  and an emissions line  233 . The emissions vapor exits the tank  202  from an exit location  236  such as a welded pipe fitting or threaded sealed fitting, A threaded sealed lining  234  is depleted hi  FIG. 2  which also includes a brass fitting  236  which connects the exit  234  to an emissions line  238  through connection  237 . The emissions vapors are drawn into the top portion  232  of the valve assembly  230  and are then passed through lines  233  and  238  into canister  225  where the vapors are treated. 
         [0020]    The top portion  232  of the emissions valve assembly  230  may be secured to the inside top or side surface of tank  202 , Additionally, or as an alternative, the emissions line  233  may be secured to a bracket  235 , such as through welding or placement in a grommet, where the bracket is secured to die inside of the tank  202 . Securing the top  232  of the valve assembly  230  or securing the emissions line  233  prevents the emissions valve assembly  230  from significant movement thereby preventing or minimizing the emissions valve assembly  230  from becoming damaged. Still further, line or tube  233  may be a metal piping or some form of tubing which may be sealed or secured to the bottom of tank  202  through use of welding, a grommet or some other fitting. 
         [0021]    When the engine is not running, pressure in the tank  202  will be released as the emissions vapor flows from the top portion  232  of the valve assembly  230  down the emissions line  233 , exits the tank  202  at the emissions exit  234  and flows into the canister  225  though line  238 . Once in the chamber  225 , the evaporate emissions vapor is treated. Upon starting the utility engine, suction is created drawing outside air through vent  222  and pulling the evaporative emissions within the charcoal canister  225  through line  224  into carburetor  220  where the evaporative emissions and hydrocarbons can be burned. During operation of the engine, emissions vapor can also be drawn into the emission valve assembly  230 , through treatment canister  225 , and into carburetor  220  where the emissions will be burned. Once the engine is shut off the suction pulling air through dm charcoal canister  225  is removed and the canister  225  is set to receive and treat the evaporative emissions within tank  202  until the engine is started again and the evaporative emissions can be drawn into and burned by carburetor  220 . 
         [0022]    As fuel  204  is added to tank  202  the fuel  204  will reach or obtain a max fuel level  206 . Exceeding the max fuel level  206  would cause fuel  204  to overflow from tank  202 . The present invention incorporates a design to prevent fuel  204  from entering the vapor emissions valve assembly  230  by sizing the valve assembly  230  so that the top portion  232  of the valve assembly  230  is above the max fuel level  206 . Specifically, the valve assembly  230  is sized so that a valve opening for receiving emissions vapor is located above the max fuel level  206  but below the top interior surface  207  of the tank  202 . The valve opening is located within the top portion  232  of the valve assembly  230 . By having the valve opening above the max fuel level  206  the opening is positioned in area  205  where vapor pressure resides but above the max fuel level  306  so that fuel does not easily flow into the emissions vapor valve assembly  230  or line  233 . Proper sizing of the valve assembly  230  may require sizing of both the valve assembly  230  and fuel tank  202 . 
         [0023]    As shown in  FIG. 2 , the tank  202  provides at least one high section or vapor area  205  which allows the top portion  232  of valve assembly  230  to reside between the max fuel level  206  and the top interior surface  207  of the fuel tank  202 . The distance between the top interior surface  207  and the max fuel level  200  has some height “h” as shown in  FIG. 2 . Understandably, Par shipping, storage, and material costs there is a benefit to minimizing the height “h” while still allowing enough space to properly place the valve opening within the top portion  232  of valve assembly  230  within area  205 . In a preferred embodiment, the height “h” is about 10 millimeters but could be as small as 1-2 millimeters and as largo as the industrial design of the tank will allow. However, it is unlikely that most tanks  202  would have an area  205  height “h” above several hundred millimeters. 
         [0024]      FIG. 3  provides a more detailed view of the top portion  332  of the emissions valve assembly  330  for an exemplary embodiment. The top portion  232  of valve assembly  330  may be connected to, in contact with or in close proximity to a top interior surface  307  of the fuel tank  202 . The emissions valve assembly  330  may be a roll over or snorkel type valve which is comprised of a ball  340  or other float like device which is responsive to the fuel level  306 . Fuel is allowed to enter the valve chamber  346  through the chamber holes  342 . As the fluid level rises, such as might happen when the unit is being moved or tilted, the bid level in chamber  346  will rise causing the float ball  340  to rise until it contacts tapered surface  348 . A seal is created when the float ball  340  contacts the tapered surface  348  preventing the fuel from entering line  333 . 
         [0025]    Under normal conditions, the float bad  340  rest on the top of the fluid surface level  306  within chamber  346  at some distance from the tapered surface  348 . The evaporative emissions are able to enter the chamber  346  from the top chamber holes  342  and flow through line  333  to the charcoal canister. The top portion  332  of the valve assembly  330  should be sized such that height “h” provides enough space to allow the evaporative emissions to escape when the float ball  340  is resting on the surface of the max fuel level  306 . 
         [0026]    As seen in  FIGS. 2 and 3 , another aspect of the top portion  332  of the valve assembly  330  may be the width “w” of the top portion  332 . In one exemplary embodiment, the tank  202  will have already been constructed with an opening located on the bottom, of tank  202  for receiving the valve assembly  230 . The opening is sized to properly receive an appropriately sized grommet or threaded fitting  234  to properly fasten and seal the valve assembly  230  to the tank  202 . After the tank  202  is assembled, the entire valve assembly  330  would be inserted into the opening. Therefore, the width “w” of the valve assembly  330  must be smaller then the width or diameter of the cutout or opening on the bottom of fuel tank  202 . One advantage of a valve assembly  330  properly sized for insertion, into an opening would be ease of removal of the valve assembly  230  for service or replacement. The valve assembly  330  or the top portion  332  could include bends or sections enabling the total, width “w” of the valve assembly  230  to be wider than the opening but no one point could be larger than the opening. Further, the opening need not be on the bottom or underside of tank  202  and could be located in various other locations on tank  202 . 
         [0027]    Additionally, all or a portion of valve assembly  230  could be placed in the tank  202  prior to complete assembly of the tank  202 . In one exemplary embodiment, the top portion  232  of the valve assembly  230  is fastened to the top surface  202  of the fuel tank  202 . The line  233  might also be fastened to a bracket  235  to support the valve assembly  330 , Finally the two halves of the tank  202  would be mated and sealed together to from the tank  202  with all or a portion of the valve assembly  230  already in tank  202 . The valve assembly or vapor exit  234  could be a welded fitting, grommet or threaded fitting to properly seal the vapor exit  234  from tank  202 , In addition to metal, the tank  202  could also be constructed using a conventional blow molded plastic technique, or other known techniques, enabling proper sizing and fitting of the tank  202  for interaction with the valve assembly  230 . 
         [0028]    Tank  202  would likely have a generally flat bottom, a generally flat top with a recessed opening  210  for cap  208 . The opening  210  for cap  208  would be lower than the highest point on the top surface of tank  202 . The integral design of the fuel vapor valve assembly  230  located within the tank  202  allows for the top surface of the tank to be clean and free from valves and lines. The tank  202  would also have four sidewalk any or all of which may be inclined or configured with a unique shape as required for a particular application. 
         [0029]    In addition to the snorkel or hall float valve depicted in  FIG. 3 , the evaporative emissions system of the present invention could use alternative valve assembly designs. As seen in  FIGS. 4A and 4B , a simple angled and open tube  433  could be used where the opening  431  resides above the max fuel level  406 .  FIG. 4B  is a side elevation view of the hoe or tube  433  depicted in  FIG. 4A .  FIG. 5  provides an additional evaporative emissions system with an inverse “J” or ISO degree bend at the top of tube  533  such that the opening  531  is below die maximum height of tube  533 . The designs depicted in  FIGS. 4A ,  4 B, and  5  do not create a seal preventing fuel from entering the line  433 ,  533  when the unit with the fuel tank  202  is tilted, slanted or moved. However, experimentation has shown that even with openings  431 ,  531  of a small diameter that very little fuel is allowed to pass through tubes  433 ,  533  even with vigorous sloshing. Still further, the evaporative emissions system  200  and the charcoal filter canister  225  can handle some fuel entering the canister  225  as it will eventually evaporate, be treated, and burned by the carburetor  220 . 
         [0030]    Still further, the evaporative emissions system of the present invention could use a valve assembly which comprises a much larger float device not within a defined valve assembly chamber. The large float would be connected or attached to the valve assembly and could have a sealing element connected or incorporated into the float design to provide a seal against the opening in the valve assembly leading to the vapor passage path or line. 
         [0031]    The present invention provides an internal evaporative emissions valve assembly which is responsive to the fuel level with the fuel tank. Further, the top portion of the fuel valve assembly, and specifically the opening in the valve assembly for receiving the fuel vapor, is positioned such that the valve assembly opening is above the max fuel level of the tank but below the interior top surface of the fuel tank. 
         [0032]    Although a preferred embodiment and exemplary embodiments of dm present invention has been described in detail the present invention is not limited to the embodiments described herein and can be modified in a variety of ways without departing from the spirit and scope of the present invention.