Abstract:
A closed fueling system with a passive vapor return comprising a cap and nozzle which selectively seal together defining passages for fuel delivery and vapor return. The cap and nozzle are sealed when the cap and nozzle are not connected together. The system optionally includes a downtube which conveys fluid to the bottom of the receiving tank, permitting filling from the bottom of the tank and minimizing atomization and vapor creation.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    Not applicable. 
       BACKGROUND OF THE INVENTION 
       [0002]    Heavy equipment, construction vehicles, aircraft, watercraft, stationary equipment, home heating tanks and stationary bulk supply tanks are typically refueled with their appropriate liquid fuels by a mobile fuel delivery tanker. The fuel is delivered to the receiving fuel tank using hoses and nozzles which typically deliver fuel at a flow rate of 60-100 gallons per minute. These systems typically lack vapor capture systems and many industrial fueling applications lack a self-stopping feature. In order to manually cut off the flow of fuel when a tank is full, an operator must stand above the fuel tank intake with a flashlight and watch for the fuel level to reach the top of the tank. Operators typically receive no protection from the fuel vapor and atomized fuel. A tremendous amount of vapor and atomized fuel are generated when heavy equipment is filled because the fuel flows very fast, and because the tanks in question are very large, so the fuel may fall for one or more meters before splashing against the bottom of the tank. Existing technology does not include mechanisms to decrease the amount of splashing. The inventor has discovered that splashing contributes to atomization and to foaming, and that vapor creation can be mitigated by minimizing the exposure of fuel to air by limiting fuel surface area. Conventional systems do not minimize the exposure of fuel to air. Because existing technology does not capture fuel vapor or atomized fuel, vapor and atomized fuel are dispersed into the environment, covering the operator and everything else in the vicinity, including nearby plant life. Existing fueling systems cannot easily be adapted to operate in extreme temperatures, and therefore when they are used in very cold or very hot places the manual fuel cut off mechanisms frequently fail when seals shrink or expand, dousing operators and the surrounding environment with fuel. 
         [0003]    Even aside from the obvious risk of combustion, petrochemicals such as diesel in contact with skin are readily absorbed into the bloodstream, and contain known toxics and carcinogens such as benzene. Diesel irritates and even chemically burns skin, eyes, nose, throat, and lungs. Breathing diesel vapors can cause kidney damage and reduce the clotting ability of blood, and diesel absorbed through the skin causes similar problems. Studies have indicated that fuel exposure is associated with an increased risk of lung cancer and prostate cancer. Diesel fuel can penetrate most glove material. Vinyl or butyl rubber gloves provide little or no protection against diesel fuel. Spilled fuel and fuel vapor is also damaging to air and water quality, and spilled fuel contaminates the ground, fouls waterways and groundwater, and injures and kills wildlife and surrounding plant life. 
         [0004]    Gasoline pumps in much of the US have been equipped with fuel vapor recovery systems at least since 1992. The systems typically include a rubber sleeve that slides over the fuel nozzle and compresses against the external rim of the gas tank outlet which is connected to the outer chamber of a coaxial hose which leads to a containment system. Vapor that escapes from the gas tank is pushed into the sleeve while being vacuumed back through the coaxial hose to the containment system. The vapor recovery system is not sealed. Any motorist knows that the rubber sleeve can be pushed back during fueling. Additionally, when the car&#39;s gas cap has been removed, fuel vapor can escape before the nozzle and fuel vapor recovery sleeve are in place as well as after they have been removed. Despite these shortcomings, gas station vapor recovery systems effectively contain around 95% of fuel vapor in these low-rate fueling operations, making gas stations much safer and much cleaner. 
         [0005]    Gas station pumps dispense fuel at around 6-7 gallons per minute. In a commercial fueling situation fuel is dispensed at 60-100 gallons per minute. At these vastly higher flow rates, atomized fuel along with a larger amount of vapor are produced, and it is expelled from the tank at a rate equivalent to that of the liquid fuel flow rate, generating much greater pressure on any component or structure intended to contain it. It is believed that this higher pressure expulsion of vapor and atomized fuel cannot be adequately contained by existing vapor recovery systems. 
         [0006]    For at least this reason, a consumer gas station vapor recovery system will not work in a commercial context. In an unsealed situation, the pressure in a high flow context would push a conventional vapor recovery sleeve back, allowing the vapor to escape. Any vapor recovery system usable in a sealed high flow situation must be able to withstand high pressures. Such a system should also operate in extreme weather, where extreme temperatures changes cause dimensional change in system components. A typical unsealed system cannot operate effectively in a high pressure situation, and a conventional sealed system is more vulnerable to failure due to component dimensional change. 
       SUMMARY OF THE INVENTION 
       [0007]    Disclosed herein is a cap for a fuel tank adapted to minimize fuel atomization during filling of said fuel tank, said fuel tank having a bottom, and said cap comprising a cap structure defining a fuel carrying passage, a valve capable of selectively sealing said passage, and a downtube in fluid communication with said fuel carrying passage and extending from said cap structure to substantially said bottom of said fuel tank. Further disclosed herein is a fueling system adapted to deliver fuel to a receiving tank having a bottom and to remove vapor from said receiving tank, comprising a fuel dispensing nozzle having a first attachment structure; a cap structure having a second attachment structure complementary to said first attachment structure, said cap structure being selectively affixable to an inlet of said receiving tank; and a downtube having sufficient length to convey fuel substantially to said bottom of said fuel receiving tank; and wherein said nozzle is selectively attachable to said cap structure via first and second attachment structures, and whereby selectively attaching said nozzle to said cap structure defines one or more fluid and vapor communication passages between said nozzle and said downtube, said one or more passages capable of conveying fuel from said nozzle to said downtube and removing vapor from said receiving tank. 
         [0008]    The foregoing and other objectives, features, and advantages of the invention will be more readily understood upon consideration of the following detailed description of the invention taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is an overall perspective view of an entire system consistent with the description herein. 
           [0010]      FIG. 2  is cut-away perspective view of a nozzle showing separate passages for liquid fuel and vapor return. 
           [0011]      FIG. 3  is an enlarged side view of a one embodiment of a cap structure as disclosed and described herein. 
           [0012]      FIG. 4  is an enlarged top view of one embodiment of a cap structure disclosed and described herein. 
           [0013]      FIG. 5  is an enlarged exploded view of one embodiment of a cap structure disclosed and described herein. 
           [0014]      FIG. 6  is enlarged perspective bottom view of one embodiment of a cap structure disclosed and described herein. 
           [0015]      FIG. 7  is a top side view of one embodiment of a cap structure disclosed and described herein showing a downtube and siphon tube. 
           [0016]      FIG. 8  is a side view of a receiving tank, showing a downtube, a siphon tube, and fuel levels. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0017]    Disclosed herein is a fueling system that is capable of accommodating high flow rates, approaches 100% vapor recovery capability, includes a drip free design leaving no wet surfaces exposed, and may include a rapid internals exchange system which can accommodate a switch between fuel types, allow for easy maintenance, and accommodate extreme heat and cold operating conditions. 
         [0018]    Referring now to  FIG. 1 , a hose structure  4  interconnects with a fuel supply tank  2  and terminates in a specialized nozzle  6 . The nozzle  6  is adapted to matingly connect with a specialized fuel tank cap structure  8  mounted on the receiving fuel tank  10  of a vehicle or piece of equipment being refueled. When operably connected, the nozzle  6 , the fuel tank cap structure  8 , the hose structure  4 , and the fuel tanks at either end of the system  2 ,  10  form a substantially sealed system. The system when correctly operated substantially prevents leaks and/or spills of liquid fuel, fuel vapor, and atomized fuel during the refueling process. Fuel and vapor can only flow when the system is operably connected and therefore sealed. Both fuel passages and vapor passages must be aligned, operably connected, and sealed in order to permit communication of materials between the hose structure and the fuel tank. If no operable connection occurs, the respective components remain sealed, and fuel is prevented from leaving the nozzle and vapor is prevented from leaving the receiving fuel tank. 
         [0019]    A hose structure  4  accommodates the flow of liquid fuel from the supply tank  2  to the receiving fuel tank  10  and accommodates the flow of fuel vapor from the receiving tank  10  to the fuel supply tank  2  or to some other fuel vapor containment system. It includes one or more chambers which carry liquid fuel from the supply tank  2  to the receiving tank  10  and one or more chambers which carry fuel vapor from the receiving tank  10  to the supply tank  2 . Because in a sealed system the liquid fuel must displace vapor in order to fill the tank, the system should be able to transport vapor in sufficient volume so that vapor flow rate does not limit liquid fuel flow rate, creating a balanced vapor recovery fueling system. The total diameter of all vapor carrying chambers should not be less than the total diameter of all liquid fuel carrying chambers. The chambers may be arranged in any configuration. For example, they may be coupled together in tandem, or they may be coaxial. Multiple hoses, separate or coupled together, may be used. The hose structure must be made from a material strong enough to withstand substantial internal pressures. 
         [0020]    As shown in  FIG. 2 , in order to form a seal and permit efficient connecting and disconnecting, the fuel nozzle  6  should be adapted to matingly interconnect with the fuel tank cap structure  8  such that interconnecting parts on at least one component can open or permit the opening of valves on the other component if and only if the two components are appropriately connected. In this way, it is impossible to dispense fuel from the nozzle  6  unless the nozzle is operably connected to the cap structure  8  such that the fuel flows into the tank, and it is impossible to release vapor from a receiving fuel tank  10  unless the tank  10  is operably connected to the nozzle  6  so that vapor flows into the fuel supply truck  2  or other containment system and is not released into the environment. Accidental spills from the nozzle  6  or supply fuel tank  2  are far less likely. Fuel nozzle  6  may also include a manual lever  14 , which opens one or more valves within the fuel nozzle  6  to permit the flow of fuel. The lever  14  may be mechanically locked unless and until the nozzle  6  is appropriately interconnected with a fuel tank cap structure  8 , making it impossible to start the flow of fuel unless the nozzle has a sealed connection with a receiving tank. 
         [0021]    Referring to  FIGS. 2 and 3 , attachment structures permit the nozzle to be operably sealed to the cap. Interlocking elements  18  may be located on the outside  20  of the fuel tank cap structure, with corresponding elements  24  located on the inside  26  of the distal end  28  of the nozzle  6  such that the distal end  28  of the nozzle slides over the outside  20  of the cap structure. Interlocking elements  24  may be notches or alignment grooves. The nozzle can be locked to the fuel tank cap structure in a variety of ways. For example, an annulus  30  located on the nozzle  6  may be rotated once the nozzle is seated on the cap structure  8 , creating an outside initial seal and aligning the valves within the nozzle  6  with the valves  42 ,  44  within the fuel tank cap structure  8 . Only when properly positioned, the valves in both components can be opened, allowing fuel flow and vapor return confined within the outside initial seal formed by the nozzle  6  and cap structure  8 . Should the annulus or other locking structure be unlocked, the valves would become misaligned, and would therefore or thereby immediately close. 
         [0022]    The nozzle  6  may contain one or more manually operated valves, such as a ball or butterfly valve, which may optionally be mechanically locked so that it is rendered inoperable in its closed position absent a seal between the nozzle  6  and cap structure  8 . Additional valves within the nozzle  6  may also be manually operated or may be automatically operated during the connecting process. Valves in the nozzle  6  may take any configuration which maintains a sealed state until the nozzle is locked on the cap structure  8  and/or the manual lever  14  is operated. 
         [0023]    Valves  42 ,  44  in the cap structure  8  maintain a closed and sealed state unless and until the nozzle is sealed to the cap structure, at which point they may opened. The same process or step which accomplishes a seal between the nozzle  6  and the cap structure  8  may operate to open the valves in the cap structure, or operation of the manual lever  14  on the nozzle  6  may cause elements within the nozzle  6  to open the valves in the cap structure. Valves  42 ,  44  within the cap structure  8  may be manually opened through the operation of an additional switch or lever (not shown). 
         [0024]    By way of example and not limitation, the valves in the cap may comprise pistons  108 ,  110 , as shown in  FIG. 5 . When the nozzle  6  is engaged and forms a seal with the fuel cap housing  102 , elements within the nozzle  6  are aligned with the pistons  108 ,  110  in the cap structure  8 . The pistons may be automatically depressed by corresponding elements in the nozzle when the two components are matingly engaged. Alternatively, the pistons may be depressed by elements in the nozzle when a lever is pulled, such as the manual lever  14 , which also opens a valve within the nozzle, or by another lever. When the pistons are depressed, a passage is created around each piston allowing fuel to freely flow through the cap structure  8  and into the receiving tank  10  and vapor to flow through the cap structure and into the hose. Fuel piston spring  112  and vapor piston spring  114  ensure the pistons remain in a closed position unless opened by appropriate elements within the nozzle. The springs are retained by fuel hose mount and internal spring retainers  116  and  118 , which may be threaded into the fuel cap housing  102  for easy removal. 
         [0025]    The fuel cap structure employs a fuel cap gasket  100  to assure a seal between the fuel cap and the fueling nozzle and prevent the escape of fuel or vapor into the environment. The fuel cap gasket  100  can be mounted to the cap structure with screws or other accessible and removable attachment structures. Fuel piston  108  carries a fuel piston gasket  104 , and vapor piston  110  carries a vapor piston gasket  106 . These gaskets assure that the pistons completely restrict the flow of fuel and vapor when the pistons are in their closed positions. The gaskets sit at the top of each piston, and can be compressed against the outer casing of the fuel tank cap structure when the pistons are closed. They can be quickly and easily accessed from the bottom of the cap structure by unscrewing the fuel hose mount and internal spring retainer  116  and the vapor hose mount and internal spring retainer  118 . Because fuel cap gasket  100  and piston gaskets  104 ,  106  can be easily accessed, they can be easily inspected and replaced if worn. They can also be replaced with materials which are appropriate for different fuel types. The same fuel cap structure can be used with different fuels simply by replacing the gaskets with gaskets appropriate for the new fuel. 
         [0026]    In this way, the nozzle and cap may be configured to be easily adapted to withstand extreme temperature changes. The harshest operating environments for commercial refueling systems frequently experience below zero temperatures. The material used for the seals in existing systems contracts under such circumstances, causing inadequate seals and dangerous spills. The systems disclosed herein may be designed with quick exchangeable internal components, as described above, to adapt the system to environmental temperature by replacing gaskets with those made of materials rated for the appropriate temperature range. In this way, temperature change induced failures of gaskets and the spills and leaks they cause can be prevented. 
         [0027]    The fuel tank cap structure is affixed to the outlet of a receiving fuel tank  10 . When its valves are closed, the tank is sealed, and the cap structure permits no vapor or liquid fuel to escape. Referring to  FIG. 6 , it may have an external housing  40  or other attachment structure adapted to matingly connect with a fuel nozzle  6 . Within the housing  40 , the cap structure defines two or more passages  41 ,  43 , each selectively occluded by valves  42 ,  44  which can be opened in order to permit access to the fuel receiving tank. At least one passage  41  is dedicated to deliver liquid fuel to the receiving tank  10 , and at least one passage  43  is dedicated to extract fuel vapor from the receiving tank. The passages are situated such that when the nozzle is locked into position, the passages communicate with the appropriate lumens of the nozzle structure such that vapor passages deliver vapor to the vapor chamber  13  of the nozzle, and liquid fuel passages deliver liquid fuel from the chamber  12  of the nozzle which carries liquid fuel. The total diameter of the liquid fuel passages should equal the total diameter of the vapor passages. 
         [0028]    The cap structure may preferably have one or more tubes extending from it into the fuel receiving tank. A downtube  48  extends substantially into the receiving tank  10 , and may extend past the bottom of the tank so that it bends and extends partially along the bottom of the tank. This tube is operably connected to the passages  41  that permit the flow of liquid fuel into the receiving tank  10 , so that when the nozzle  6  is connected to the cap structure  8  and fuel flows through the nozzle and through the cap structure, the fuel fills the tank by flowing through the downtube  48  to the bottom of the tank. For example, the downtube may be connected to the fuel hose mount and internal spring retainer  116 , shown in  FIG. 5 . As the fuel level  50  in the receiving tank  10  gets higher, the fuel will actually be dispersed under the existing fuel level preventing the fuel from falling through the air in the tank. The downtube  48  allows the tank to fill from the bottom up, and prevents the fuel from splashing, which significantly reduces the foaming of the fuel, which in turn eliminates the creation of atomized fuel from fuel disturbance to be disbursed in the air. It also substantially decreases the formation of fuel vapor by minimizing the surface area where liquid fuel is exposed to air. 
         [0029]    One or more siphon tubes  52  extend into the tank to a pre-determined fill level, indicated by dashed line  51  in  FIG. 8 . The siphon tube or tubes  52  are operably connected to the vapor return passages  43 , such that vapor return structures in the nozzle and vapor return structures of the hose can remove fuel vapor from the tank even without pumping assistance. The liquid fuel is pumped from the fuel supply tank  2  into the fuel carrying lumen of the hose structure  4 , through the nozzle  6  and the cap structure  8 , and into the receiving tank  10  at significant velocity. The flow of fuel into the receiving tank displaces fuel vapor, and in a sealed system expels the vapor at significant positive pressure. The removal of fuel from the fuel supply tank also generates a natural negative pressure vacuum in the vapor return portion of the sealed system, which is capable of extracting vapor from the tank without additional pumping. This combination of negative and positive pressure working together to replace liquid mass with gas is known as a balanced vapor return system. 
         [0030]    The hose structure  4 , nozzle  6 , and fuel tank cap structure  8  must be capable of withstanding the significant pressures generated by the high rate of the fuel flow. The connection of the nozzle to the cap structure also must be capable of withstanding high pressure. For that reason, the pressure-based connections used in consumer grade gas stations will not work. An interlock or something equivalent to an interlock is necessary. 
         [0031]    When the fuel level  50  in the tank covers the bottom of the siphon tube or tubes  52 , it causes a change in pressure within the vapor return section of the nozzle, which in turn causes suction across a diaphragm that can disengage the manual lever, causing all valves to shut, cutting off the flow of fuel and sealing both the nozzle and fuel tank cap structure. It is then safe for the operator to unlock and/or remove the nozzle from the cap structure. Separating the nozzle from the cap and the mating surfaces of the plungers leaves no wet surfaces exposed. Spills of liquid fuel and release of vapor are far less likely than with conventional systems. 
         [0032]    The fuel tank cap structure can be a universal structure pared with an install kit specific to the existing fuel fill spouts of commonly used fuel receiving tanks so that the cap structure may be affixed to an existing fuel tank inlet without significant modification. The fuel cap structure seals the fuel tank. A two way check valve may be installed on an existing vent to regulate pressure differences inside the receiving tank due to temperature changes which may cause contraction and expansion of fuel. 
         [0033]    The terms and expressions which have been used in this specification are intended to describe the invention, not limit it. The scope of the invention is defined and limited only by the following claims.