CROSS REFERENCE TO RELATED APPLICATION 
   The present invention is a divisional of U.S. patent application Ser. No. 10/693,183 filed Oct. 24, 2003, now U.S. Pat. No. 6,854,491, entitled “Low Surface Energy Fuel Nozzle”. The patent application Ser. No. 10/693,183 is incorporated herein by this reference. 


   STATEMENT REGARDING FEDERALLY SPONSORED R&amp;D 
   Not applicable to this application. 
   TECHNICAL FIELD 
   This invention relates to a fuel nozzle and more particularly to a fuel dispensing nozzle that has three or more spaced apart protrusions extending from an exterior surface of the nozzle spout. 
   BACKGROUND OF THE INVENTION 
   Fuel dispensing nozzles are widely used and understood in the field. Early fuel nozzles are mainly comprised of a manual actuated valve and a metallic spout for directing fuel into a desired container. Many improvements have been made to fuel nozzles, including U.S. Pat. No. 4,453,578, which provide the means of automatically stopping fuel flow when the fuel reaches a desired level. 
   In addition, many design improvements have been made regarding nozzle spouts. U.S. Pat. No. 5,765,609 describes a method for manufacturing an aluminum spout that removably attaches to a nozzle body. Removable spouts enable them be replaced in shorter intervals than the more expensive nozzle body. Replacing a spout may be desirable when a nozzle is left in a motor vehicle after drive-away, upon considerable wear, or as improved spouts become available. 
   Recently, significant attention has been directed to the adverse environmental effects caused by fuel dispensing nozzles. One such effect is caused by fuel vapors displaced from a container as heavier liquid fuel is dispensed into the container. The displaced vapors contain volatile organics that chemically react with nitrogen oxides to form ground level ozone, often called “smog”. Ground level ozone can potentially cause irritation to the nose, throat, lungs and bring on asthma attacks. In addition, gasoline vapors are suspected to contain other harmful toxic chemicals, such as benzene. 
   In an effort to reduce the amount of harmful vapors that reach the atmosphere, a vapor recovery nozzle has been developed; one version of the spout is best described by U.S. Pat. No. 4,351,375. This version of a vapor recovery nozzle is comprised of a coaxial tube that both dispense fuel through a main tube and vacuum vapors through a secondary channel. A large percentage of the captured vapors are treated and safely released in the atmosphere. Vapor recovery systems are required by the laws of many states, especially at high volume stations or stations located in densely populated areas. California&#39;s Air Resource Board (CARB) is largely responsible for setting forth new standards for fuel dispensing nozzles. 
   Although vapor recovery has significantly reduced the amount of volatile organics that reach the atmosphere during fueling, there are several other sources of fuel vapors that contribute to the problem of “smog”. One such source is fuel dripped from a nozzle spout after fueling. Typically, when a nozzle is deactivated there is a delay before the user removes the nozzle spout from the container to be filled. If the delay is sufficient, drops from the spout will fall into the container. If the delay is insufficient, drops fall onto the ground or the local filling equipment. Spilt fuel evaporates into the atmosphere and contaminates the ground. Even waiting a significant amount of time before removing the nozzle will not ensure that drips will not occur. Some users try to supplement waiting by tapping the nozzle spout on the fill tube of the container prior to removing it. 
   Another source of “smog” is caused by fuel residing on the nozzle after fueling. Residual fuel is caused by adhesive forces between the nozzle surfaces and the fuel. Fuel can reside on both the inside and outside surfaces of a spout. As with dripping, residual fuel evaporates into the atmosphere. 
   In an effort to reduce sources of “smog” not directly addressed through vapor recovery, many new nozzle requirements and laws have been implemented. Many new nozzle designs are directed towards the goals of further reducing fuel vapor sources, such as U.S. Pat. No. 6,520,222, U.S. Pat. No. 5,603,364, U.S. Pat. No. 4,213,488, U.S. Pat. No. 5,645,116, and U.S. Pat. No. 5,620,032. Although the aforementioned patents may potentially serve in the direction of their intended purposes, most are unlikely to reliably provide true “dripless” performance. None of the aforementioned patents address the issue of residual fuel on the outside surface of a nozzle, caused by splashing. Many of the aforementioned patents are not compatible with both, standard type nozzles and vapor recovery type systems. Many of the aforementioned patents require substantial change over costs. 
   In these respects, the low surface-energy, fuel-dispensing nozzle according to the present invention substantially departs from conventional concepts of the prior art, and in doing so provides an apparatus primarily designed for the purpose of reducing the amount of vapor that reaches the atmosphere during a fueling cycle. 
   SUMMARY OF THE INVENTION 
   The present invention therefore aims at providing a nozzle that reduces the amount of residual fuel on the spout after a fueling cycle is completed. In addition, the present invention aims at reducing the number of drips that occur after the nozzle is removed from a container. The present invention is comprised of a fuel dispensing nozzle housing a valve for regulating fuel flow. Downstream of the valve is a tubular spout for directing the fuel towards or into a container. One or more of the surfaces of the tubular spout have a surface energy less than that of aluminum. The low surface energy surfaces cause the fuel to bead up rather than wet-out, as is the case with aluminum and aluminum alloys. Beading of droplets results in more drops falling into the container and less fuel to reside on the spout surfaces after fueling. The nozzle spout of the present invention may include three or more spaced apart protrusions that extend from a discharge end and towards the nozzle body. The three or more spaced apart protrusions provide electrical grounding to the nozzle and allow non-conductive spout materials to be used for the spout. Separately, or in addition, the spaced apart protrusions provide wear protection to the materials on the exterior surface of the spout. The protrusions are in a spaced apart relationship that ensures nozzle contact with the container to be filled. 
   These and other features, aspects, and advantages of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings. 


   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Preferred embodiments of the invention are described below with the reference to the following accompanying drawings: 
       FIG. 1  is a perspective view of a prior art standard nozzle assembly; 
       FIG. 2  is an end view of a prior art spout; 
       FIG. 3  is a perspective view of a nozzle spout with a cutaway to show the inside low surface energy surface of the spout, including an alternative embodiment “dripless” feature; 
       FIG. 4  is a perspective view of a nozzle according to the present invention with the outer surface having a low surface energy; 
       FIG. 5  is a perspective view of an alternative embodiment of the present invention with grounding and protection protrusions; 
       FIG. 6  is a top view of the alternative embodiment spout of  FIG. 4  inserted into a typical fuel tank orifice; and, 
       FIG. 7  is a side view of a drop of fuel on a surface of a spout with a low surface energy according to the present invention. 
   


   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Many of the fastening, connection, manufacturing and other means and components utilized in this invention are widely known and used in the field of the invention are described, and their exact nature or type is not necessary for a person of ordinary skill in the art or science to understand the invention; therefore they will not be discussed in detail. 
   The term “rib” as used herein includes, without limitation, any protrusion from a surface, as well as any protrusion resulting from the removal of material into the surface. 
   As used herein, any surface X that is later referred to as X′ (prime) indicates that X has been improved, according to the present invention, to X′. 
   Applicant hereby incorporates by reference the following U.S. patents: U.S. Pat. No. 5,765,609; U.S. Pat. No. 5,603,364; U.S. Pat. No. 4,453,578 and U.S. Pat. No. 5,213,142. 
   Referring now to the drawings,  FIG. 1  shows a prior art fuel dispensing nozzle assembly  10 . Nozzle assembly  10  may be used for dispensing a fuel such as, but not limited to, gasoline or diesel. Typically, nozzle assembly  10  is comprised of a nozzle body  11  which houses the components necessary for safely regulating the flow of fuel. Fuel travels from a fuel supply via a pump and hose system (not shown) to a nozzle inlet end  16 , through a valve assembly  12 , into a spout  20 , and out a discharge end  18 . Fuel flow is initiated by a user moving an actuator  14 . Fuel flow typically stops due to either the user releasing actuator  14  or by valve assembly  12  sensing a full condition and automatically releasing actuator  14 . Detailed descriptions of above components are described by U.S. Pat. No. 4,453,578 but are not necessary for one skilled in the art to understand and appreciate the present invention, thus they will not be discussed in further detail. 
   In many fuel nozzles, spout  20  is removably attached to nozzle body  11 . Spout  20  is inserted into nozzle body  11  and the assembly is secured by means of a spout screw  19  (only hole shown). Spout  20  is sealed through the use of one or more o-rings (not shown). As shown in  FIG. 2 , spout  20  has an inside direct contact surface  22  and an outside indirect contact surface  23 . Direct contact surface  22  directs the flow of fuel from nozzle body  11  down the length of spout  20  and into the container to be filled. The length of travel from nozzle body  11  to discharge end  18  is roughly 9 inches. When spout  20  is inserted into the container to be filled, about 3.5 inches of its length (starting from end  18 ) is within the container. Spring  24  is placed onto spout  20  to keep the spout from being over inserted. Because spout  20  is inserted substantially within the container to be filled, not only does direct contact surface  22  wet with fuel, but indirect contact surface  23  becomes wet due to splashing within the container. During a fuel cycle and for a standard unleaded nozzle ( 13/16 inch diameter-non-vapor recovery) the total surface area of the nozzle in contact with the fuel is roughly 25 square inches. A diesel nozzle, with an outside diameter of 1 inch, provides substantially more. 
   As described by U.S. Pat. No. 5,765,609, a 6005-T5 aluminum material is viewed as an ideal choice for high volume spout production. It can be extruded, turned on a lathe, punched, bent, drilled and formed. In addition, aluminum is lightweight, relatively inexpensive compared to other lightweight materials, and provides the required rigidity and strength. Aluminum, and aluminum allows, are typically inert to the fuels they dispense and are electrically conductive. It can be easily seen why aluminum and aluminum alloys constitutes all, or nearly all, spouts in use today. 
   A significant drawback to the use of aluminum in spouts, and the direction of the present invention, is that aluminum causes unnecessary fuel dripping and liquid retention. Although the use of aluminum facilitates manufacturing low cost spouts, it is at the expense of releasing fuel vapors into the atmosphere. While many are designing “dripless” nozzles, the root cause has gone unsolved and unimproved. 
   The interaction of a liquid droplet and a surface is subject to physical laws and formulas. When a drop is placed onto a surface it can either wet-out into a very thin dispersed film, or it can bead up on the surface. The determination on whether a drop will wet-out or bead up is a function of the relative difference between the surface tension of the liquid in the drop, and the surface energy of the surface on which the drop is placed. A typical bead is shown in  FIG. 7 , wherein a drop  50  is in direct contact with a low surface energy surface  22 ′. Contact angle  52  provides indication at the degree in which drop  50  is in contact with surface  22 ′. Contact angle  52  can be predicted by Young&#39;s Equation which states the solid-vapor interfacial tension minus the solid-liquid interfacial tension equals the liquid-vapor interfacial tension multiplied by the cosine of critical angle  52 . 
   With a horizontal surface (not shown) drop  50  will be symmetrical. In the case of a vertical surface, drop  50  is likely to deform in the direction of gravity, as shown by the arrow marked “G”. Thus,  FIG. 7  is shown simplified for a vertical surface. Under the influence of gravity, drop  50  may or may not move in the direction of gravity. If drop  50  is sufficient in size and density to overcome the adhesive forces between it and surface  22 ′, it will slide or fall. Thus, in the case of wanting drop  50  to move in the direction of gravity it is desirable to make surface  22 ′ (also applies to surface  23 ′) with a very low surface energy and to have drop  50  have a very high surface tension. Because fuel surface tension properties are relatively fixed, movement of drop  50  is a largely a function of surface energies. 
   In the case of aluminum spouts used for dispensing fuel, aluminum has a much higher surface energy than the surface tension of gasoline or diesel. Aluminum typically has a surface energy close to  45  dynes per centimeter and gasoline has a surface tension close to 21.6 dynes per centimeter. Diesel has a larger surface tension than gasoline at roughly 30 dynes per centimeter. Thus, it can easily be seen that with aluminum, a spout is easily wet-out by both gasoline and diesel. This creates a highly undesirable situation in terms of fuel drips, fuel retention, and vapors released into the atmosphere. 
     FIG. 3  shows both a preferred and alternative embodiment of the invention. The preferred embodiment is wherein direct contact surface  22 ′, located within spout  20 , is a low surface energy surface. Even though only a portion of direct contact surface is shown, the entire surface  22 ′, extending from discharge end  18  to valve assembly  12 , can benefit from having a low surface energy. During fueling, fuel flows as normal. When fuel flow is stopped, fuel along contact surface  22 ′ is encouraged to bead up. By beading up, again as shown in  FIG. 7 , the fuel is subject to the force of gravity and momentum. Significant amounts of fuel that would otherwise be left on spout  20  drips into the container to be filled prior to the user removing spout  20 . The result is more fuel dispensed into the container, less drops on the ground, and less fuel evaporating off nozzle assembly  10 . 
   The present invention has been tested and shown to significantly reduce residual fuel on spout  20 , in comparison to aluminum and other wet-able surfaces, such as an anodized aluminum, nylon, and ABS material. As a preferred embodiment of the invention, standard 6005-T5 aluminum surfaces from a commercially available OPW 11 series nozzle (a trademark of the Dover Resource Corporation) were coated with a fluoropolymer coating. PFA (perfluoroalkoxy), a member of the Teflon family (a trademark of DuPont), was chosen due to its ability to be applied at a low cost, its low surface energy (roughly 18 dynes per centimeter), its low porosity, and its chemical resistance to fuels. Using gasoline, improved inside direct contact surface  22 ′ was shown to reduce residual fuel by roughly 33% over unimproved direct contact surface  22 . Further surface treatments and surface preparations, such as removing all burrs and scratches prior to coating are likely to make an increased improvement. 
   Now referring to  FIG. 4 , spout  20  is shown with indirect contact surface  23 ′. As with direct contact surface  22 ′, indirect contact surface  23 ′ can be coated from end  18  to valve assembly  12 , however because only the first portion of spout  20  is indirectly exposed to fuel only the first portion needs to have a low surface energy. Residual fuel on surface  23 ′ contributes to vapor emissions, creates fuel drips and is unaddressed by any “dripless” features. 
   Although  FIG. 3  and  FIG. 4  show surfaces  22 ′ and  23 ′ coated individually, the improvements can be combined. Testing of both surfaces together has yielded improvements up to 56% using gasoline and over 65% with diesel. 
   It should be appreciated that reductions of drips and residual fuel on spouts is not limited to just standard (non-vapor recovery) nozzles as shown. Although providing the means to improve the environmental performance of non-vapor recovery nozzles is a significant feature of the present invention, the present invention can be applied to vapor recovery systems and new “dripless” nozzles. Wherein vapor recovery systems and “dripless” nozzles may eliminate a pound of gasoline vapor for dollars of equipment costs, the present invention can remove a pound of vapor for pennies in cost. The present invention can be incorporated in all types of nozzles with very little cost impact. 
   A “dripless” spout, similar to one described by U.S. Pat. No. 5,603,364, is shown in  FIG. 3  and forms the alternative embodiment previously mentioned. “Dripless” assembly  30  is located at the most downstream location possible, typically adjacent to discharge end  18 . A wire  32  is attached to valve system  12 , or actuator  14 , and to a plunger  36 . Plunger  36  is pulled against a seat  34  wherein the interaction of seat  34  and plunger  36  discourages residual fuel within spout  20  from reaching discharge end  18 . A problem with “dripless” assembly  30  is it too has surface area in contact with fuel and the higher surface energy plastic or metallic materials used therein are subject to clinging fuel and resulting drips. The present invention further reduces dripping in “dripless” nozzles. 
   In addition to “dripless” nozzles, the present invention is applicable to balance and assist vapor recovery systems. Although a vapor assist nozzle has not been tested, the present invention is likely to improve the environmental performance of such nozzles due to the fact that vapor assist nozzles typically use coaxial spouts and added features and orifices which all increase the surface areas subject to direct or indirect contact fuel. Any of such surfaces may be improved by the present invention, including vapor recovery passages made from nylon. In addition, vapor recovery offers improved performance due to the airflow it creates. As shown in  FIG. 7 , an airflow  56  travels over and around drop  50 . With a surface that is wet-out with fuel, as is the case with aluminum, the residual fuel is unlikely to be affected by airflow  56 . In the case of fuel on a surface according to the present invention, drop  50  has a substantial critical angle which pushes drop  50  away from surface  22 ′ and into airflow  56 . The result is likely to provide an even further efficient vapor recovery system. 
   Even though a thin PFA coating has been disclosed as the best mode of the present invention, it is not limited to such and the present invention should not be construed to be limited to a fluorocarbon, a fluoropolymer, or a Teflon coating (trademark of Dupont). Many other materials may be applied, or used, to provide low surface energy surfaces. This includes materials which may be deposited by CVD, dipped, sprayed, and electrostatically deposited. In addition, the spout may be manufactured from a material that has a low surface energy, such as from a molding process for example. All fall within the spirit of the present invention. 
   Since many low surface energy materials are not electrically conductive,  FIG. 5  and  FIG. 6  show another alternative embodiment of the present invention. When indirect contact surface  23 ′ is non-conductive, one or more ribs  26  can be formed or attached to surface  23 ′ which provide conductive surfaces. Ribs  26  protrude past surface  23 ′ and ensure contact with a container inlet  40  as shown in  FIG. 6 . As is the case with recent attentions brought to electrostatic charges causing fuel station burn accidents, it may be desirable to have a non-conductive spout. For this case, ribs  26  should be omitted. In addition to grounding, ribs  26  can be used to protect surface  23 ′ from wear. Although ribs  26  is shown to have 4 individual ribs, it is preferable to have at least 3. 
   While the low liquid retention fuel nozzle systems herein described constitute preferred embodiments of the invention, it is to be understood that the invention is not limited to these precise form of assemblies, and that changes may be made therein without departing from the scope and sprit of the invention as defined in the appended claims.
A fuel dispensing nozzle having a valve for controlling the flow of fuel to a spout attached to the nozzle. The nozzle spout includes three or more spaced apart protrusions that extend from an outer surface of the spout. If the outer spout surface is made from a non-electrically conductive material, the plurality of protrusions may be made from a electrically conductive material, and thus, provide electrical grounding to the nozzle. If the outer spout surface is made from a material having less than ideal wear properties, the plurality of protrusions may be used to provide wear protection to the outer surface.