Patent Publication Number: US-2002007804-A1

Title: Fuel additive controlling and maintaining apparatus

Description:
TECHNICAL FIELD  
       [0001] The invention pertains to the general field of engine fuel additives and more particularly to an apparatus that allows an engine fuel to be enriched with a controllable concentration of carbon dioxide to aid in reducing engine exhaust soot.  
       BACKGROUND ART  
       [0002] At normal temperature, hydrocarbon fuels, such as diesel fuel, absorb about one volume of gaseous carbon dioxide in an equal volume of the diesel fuel. If the gas-enriched fuel is loaded into a fuel tank in the normal manner, some of the gas will desorb due to liquid turbulence, splashing, fuel heating and fuel usage. Removing fuel from the tank can either cause ullage gas replacement by intake air or desorbed CO 2  from within the fuel. When such desorption of CO 2  from the fuel occurs, the fuel may not retain enough absorbed gas for useful purposes. The gas-retaining apparatus described herein, eliminates the loss of absorbed CO 2  gas by the diesel fuel during normal fuel usage.  
       [0003] A search of the prior art did not disclose any patents that read directly on the claims of the instant invention.  
       DISCLOSURE OF THE INVENTION  
       [0004] In its basic design, the fuel additive controlling and maintaining apparatus is comprised of:  
       [0005] At least one gastight bag containing a mixture of gas and air,  
       [0006] At least one vehicle fuel tank containing a gas-enriched fuel comprising a mixture of gas and a liquid hydrocarbon fuel. The vehicle fuel tank also contains an ullage, located above the gas-enriched fuel, and  
       [0007] A gas conduit located between the gastight bag and the ullage.  
       [0008] The fuel additive controlling and maintaining apparatus is designed to manage the bi-directional flow of the mixed gases between the gastight bag and the ullage. The apparatus stabilizes and maintains the concentration of the gas in the fuel during engine operation by replacing an increased fuel tank ullage with an equal amount of the mixed gases that are transferred from the gastight bag.  
       [0009] The gastight bag receives the mixed gases during the initial fueling and refueling operations. The mixed gases flow into the fuel tank ullage as the fuel is depleted by the engine to prevent desorption of the gases from the remaining fuel. The gastight bag is dimensioned to provide an expanded volume equal to the volume of the fuel tank, and is located above the fuel tank, within a protective enclosure.  
       [0010] In view of the above disclosure, the primary object of the invention is to provide an apparatus that is capable of significantly lowering the amount of soot produced by conventional hydrocarbon engines.  
       [0011] It is also an object of the invention to provide an apparatus that:  
       [0012] can lower fuel consumption and increase mileage in a vehicle, lowers the amount of engine exhaust emissions that are released into the air,  
       [0013] can prolong the useful life of an engine equipped with the apparatus,  
       [0014] is easy to install and operate,  
       [0015] is low maintenance, and  
       [0016] is cost effective from both a manufacturer&#39;s and consumer&#39;s point of view. 
     
    
    
     [0017] These and other objects and advantages of the present invention will become apparent from the subsequent detailed description of the preferred embodiment and the appended claims taken in conjunction with the accompanying drawings.  
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0018]FIG. 1 is an elevational-sectional view showing a gastight bag, located within a protective enclosure, directly connected, via a gas conduit, into the ullage of a vehicle gas tank.  
     [0019]FIG. 2 is an elevational-sectional view showing a gastight bag, located within a protective enclosure, with a gas conduit disconnected from the vehicle gas tank.  
     [0020]FIG. 3 is a graph showing the measured soot produced in a diesel engine with different concentrations of carbon dioxide in the diesel fuel.  
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION  
     [0021] The best mode for carrying out the invention is presented in terms of a preferred embodiment for a fuel additive controlling and maintaining apparatus  10  (hereinafter “FACMA  10 ”).  
     [0022] The absorption of CO 2  in a hydrocarbon fuel, such as diesel fuel, reduces the emission of soot from the engine as the fuel is used in the engine. It is believed that the absorbed CO 2  gas forms micro bubbles in the fuel droplets and helps create smaller droplets. It is necessary to maintain a concentration of CO 2  in the fuel in order to achieve a certain reduction of soot. If the con concentration drops, the soot increases. In order to keep a fixed level of CO 2  in the fuel, a mating concentration of CO 2  must be applied into the ullage of the fuel tank. Normally the use of the fuel will pull air into the ullage. The presence of air in the ullage of the CO 2 -charged fuel will start to desorb CO 2  from the fuel until equilibrium is reached between the concentrations of the two phases of the CO 2  in the fuel tank. By supplying a mixture of CO 2  and air into the ullage, it is possible to prevent the desorption of CO 2  from the fuel.  
     [0023] As shown in FIGS. 1 and 2, the FACMA  10  is comprised of three major elements: at least one gastight bag  11  containing a mixture of gas and air (“mixed gases”); at least one vehicle fuel tank  14  containing a gas-enriched fuel comprising a mixture of gas and a liquid hydrocarbon fuel, and having an ullage  16  located above the fuel; and a gas conduit  18  located between the gastight bag  11  and the ullage  16 . As stated above, the FACMA  10  is designed to maintain the gas within the fuel at a predetermined concentration.  
     [0024] For disclosure and description within this patent application, the gas within the gastight bag  11  is comprised of carbon dioxide (CO 2 ), and the gas-enriched fuel is comprised of a mixture of CO 2  and diesel fuel. It is also believe that the FACMA  10  will be equally effective when used with other types of fuel, such as “Jet A” jet fuel.  
     [0025] The optimal ratio of the volume percent of the CO 2  gas in the ullage  16  of the fuel tank  14 , to the volume of the CO 2  gas in the fuel is maintained at a value between 0.25 and 1.25.  
     [0026] The gastight bag  11 , as shown in FIGS. 1 and 2, is comprised of a durable material having a flexibility which provides for numerous repeated cycles of bag pressurizations and decompressions. As also shown in FIGS. 1 and 2, the gastight bag  11  is enclosed within a protective enclosure  20  that surrounds and protects the bag  11  from damage. A gastight bag conduit  12  located within the gastight bag  11  has at least one port  13  for allowing the bi-directional flow of the mixed gases.  
     [0027] The gastight bag  11  within the protective enclosure  20  is dimensioned to hold a volume of gas not exceeding the vehicle fuel tank&#39;s volume. The enclosure  20  is preferably located within a vehicle void space or the enclosure  20  can be located within the body of an aerodynamic deflector above the cab of a truck-tractor.  
     [0028] The protective enclosure  20  has at least one air inlet  22  and a separate coupling means  24  for coupling the gastight bag  11  to the gas conduit  18 , which is connected to the protective enclosure  20 , as shown in FIGS. 1 and 2.  
     [0029] As also shown in FIGS. 1 and 2, the vehicle fuel tank  14  has a fuel tank cap  28  with the gas conduit  18  attached thereon to provide for the conveyance of the mixed gases in and out of the fuel tank  14 .  
     [0030] A controllable gas source  32 , as shown in FIGS. 1 and 2, is used to supply the desired gas mixture into the gastight bag  11 . An additional coupling means  34 , as shown in FIG. 2, is utilized to couple the opposite end of the gas conduit  18  to the gas source  32 . Whenever the FACMA  10  is used on a truck-tractor, the driver will attach the additional coupling means  34  to the gas source  32  at the same time that the truck is being fuel or refueled, as shown in FIG. 2.  
     [0031] As shown in FIG. 1, the gas conduit  18  is attached to the fuel tank cap  28  and extends therethrough. The fuel tank cap  28  also has at least one seal  38  to prevent gas leakage and to promote the conveyance of the mixed gases through the gas conduit  18 .  
     [0032] A normally-open gas-control valve  40 , as shown in FIG. 2, is automatically closed when the gas conduit  18  is disconnected from the fuel tank  14 , and is reconnected to the controllable gas source  32 . Once the refueling is completed, the gas conduit  18  is disconnected from the gas source  32  and reconnected to the fuel tank  14 .  
     [0033] In order to insure that the gastight bag  11  does not become over-pressurized, a pressure/vacuum relief valve  42 , as shown in FIGS. 1 and 2, is located on the protective enclosure  20  and connected to the gas conduit  18 .  
     [0034]FIG. 3 shows the measured soot produced in a diesel engine with different concentrations of CO 2  in the diesel fuel. The testing was done to EPA requirements with three different test modes:  
     [0035] 1. cold start (cool down overnight),  
     [0036] 2. hot start (two minutes cool down) and  
     [0037] 3. sustained run—hot start after ten minutes cool down and little acceleration during the test.  
     [0038] There is scatter in the data, but the general trend is a reduction in soot with increased CO 2  in the fuel.  
     [0039] While the invention has been described incomplete detail and pictorially shown in the accompanying drawings it is not to be limited to such details, since many changes and modifications may be made to the invention without departing from the spirit and the scope thereof. Hence, it is described to cover any and all modifications and forms which may come within the language and scope of the claims.