Patent Document

BACKGROUND OF THE INVENTION 
   Systems are found throughout the world for managing delivery of liquids from a storage tank to a contained space such as a tank or other container. Typically, a pump is provided to pressurize the liquid as it is being delivered, but gravity may also be used on occasion. For example, fuels such as gasoline or diesel fuel are delivered by a pump from a storage tank to vehicle fuel tanks. While the invention can be used for a variety of liquids, we feet at this time that it will be most useful for liquid fuel delivery. 
   Such delivery occurs most frequently at retail gas stations where end users (motorists) manage the delivery themselves. Liquid fuel delivery will be used as the example to explain the invention. Other types of liquids and systems may be able to take advantage of the invention as well. 
   Colloquially, the term “gas pump” is used to refer to the entire fuel delivery unit. To avoid confusion, hereafter we will use the term “pump system” to refer to the entire device that pumps, meters, and controls fuel flow to a vehicle or other fuel holding tank. The term “fuel pump” or “gas pump” refers to the actual pump that pulls and pressurizes liquid fuel contained in a larger storage tank. 
   In a pump system, the fuel pump provides pressurized fuel to a metering system that determines the amount of fuel that flows during a fuel delivery event. The pressurized fuel is supplied to a manually operated fuel nozzle through a hose. Fuel nozzles are used to safely manage this fuel delivery. The decades-old design still in use for fuel nozzles has an internal main fuel valve that is manually operated by a motorist with an external lever. Fuel flowing from the valve passes through a spout inserted into a filler pipe of the vehicle, and then into the tank to be filled. The motorist wishing to fill a fuel tank operates the lever to control and stop fuel delivery. 
   Fuel nozzles now usually include a detent to hold the lever in one of several positions providing various rates of flow. A sensor detects imminent overflow and releases the detent to prevent spillage. These sensor mechanisms work quite well in shutting off fuel flow before spillage occurs. 
   However, small amounts of fuel usually remain in the nozzle and particularly, the spout after the main valve closes. When the motorist removes the spout from the filler pipe, this fuel can drop to the ground or drip on the paint surrounding the filler pipe. This fuel escaping from the spout after the main valve closes is a safety hazard, causes both air and ground pollution, and can damage the paint around the filler pipe. Accordingly, this fuel escape is undesirable, and should be minimized. 
   A number of different systems have been developed over the years to reduce this fuel escape. U.S. Pat. Nos. 5,337,729 and 6,331,742 for example provide check valves at the end of the spout to retain fuel within the spout after the main valve has closed. 
   BRIEF DESCRIPTION OF THE INVENTION 
   We have developed a different type of system for preventing escape of liquids such as fuel when that liquid is transferred from a tank to another contained space such as a tank. Instead of attempting to retain the liquid remaining in the liquid nozzle downstream from the main valve, our system purges the nozzle and spout before the spout is removed from the filler pipe or opening. Most of the liquid remaining in the nozzle and spout (hereafter downstream chamber, or more briefly, chamber) is ejected or purged by a jet of compressed air or other noncombustible gas that is automatically blown into the downstream chamber each time the lever controlling liquid flow is released. 
   Such a liquid delivery system for controlling the flow of a pressurized liquid to a storage tank or other contained space and reducing the amount of escaping liquid when the delivery process is complete, includes a nozzle with a housing having internal ducting receiving the pressurized liquid from a source such as a hose. A liquid valve is operable between an open setting allowing flow of liquid through the ducting and a closed setting opposing liquid flow. Typically an actuator such as a lever to be operated manually controls the liquid valve setting. 
   A spout attached to the housing receives liquid from the liquid valve for delivering the liquid to the storage tank. The spout has an internal passage defined by an internal surface and an outlet from which liquid flows into the vehicle or other tank. 
   An air vent is located within the spout. An air valve controls flow of compressed air from a source typically external to the nozzle, to the air vent. The air valve opens responsive to an actuation force. A purge linkage between the liquid valve and the air valve provides actuation force to the air valve responsive to a change in the liquid valve from the open setting to the closed setting. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows an interior side view of a fuel nozzle incorporating the invention. 
       FIGS. 2   a - 2   c  show one design for a purge controller. 
       FIGS. 3 and 4  are side and end views of an upstream portion of the nozzle containing one form of an air vent for directing air through the fuel spout. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1  shows an interior view of a simple fuel nozzle  10  that incorporates the invention and that may form part of a fuel delivery system. As mentioned, the design can apply to liquids other than fuel. 
   A housing  12  encloses the various elements in this embodiment, although other configurations are easily possible. A conventional design for a nozzle  10  has an internal inlet fuel duct  21  having an external threaded fitting  15  for attaching to a hose carrying pressurized fuel provided by a fuel pumping system. As will be discussed, future fuel delivery system designs may place many control components outside the nozzle housing  12 . 
   A fuel valve  25  is shown in generic form. Fuel valve  25  can be operated between at least one open setting and a closed setting in which no fuel can flow through valve  25 . Fuel valve  25  can have any suitable design that reliably controls fuel flow from inlet duct  21  to an outlet duct at  55 . A spout  39  has an internal passage that receives fuel flowing from fuel valve  25  and through outlet duct  55 . Fuel in spout  39  flows from a spout outlet  58  into the tank to be filled. Duct  55  and spout  39  will be referred to hereafter as the downstream chamber. 
   Valve  25  is operated by an actuator such as flow control lever  45 , typically pivoted on a shaft (not shown) within housing  12 . A guard  16  attached to the outside of housing  12  shields lever  45  from inadvertent actuation. Lever  45  is shown in the no-flow position for valve  25 . 
   A link  49  is connected between lever  45  and fuel valve  25 . When lever  45  is moved in the direction of the adjacent arrow, link  49  operates valve  25  into the open setting. A spring, not shown, constantly urges fuel valve  25  and lever toward the closed setting. Link  49  can take any convenient form that reliably and efficiently controls the fuel valve  25  setting. 
   The invention uses a rapid flow of air or other noncombustible gas through outlet duct  55  and spout  39  immediately after valve  25  is closed, to drive or purge fuel wetting the internal surfaces of duct  55  and spout  39  into the tank to be filled. (The term “air” is intended to include any noncombustible gas.) To accomplish this, an air (non-combustible gas) duct  18  supplies compressed air or other non-combustible gas to an air (non-combustible gas) valve  28 . The compressed gas source may be an external compressor connected by a hose to the end of duct  18 , or can be internal to housing  12 . Air valve  28  controls flow of compressed air to an outlet pipe  31  that supplies the compressed air to an air vent  42  within the downstream chamber and adjacent to the upstream end thereof. Air vent  42  is oriented to direct air flow toward the spout outlet  58 . 
   The volume and velocity of air supplied must be adequate to purge the internal surfaces of the downstream chamber of the fuel film remaining after the liquid fuel has drained from the space. More will be said below about these considerations. 
   Vent  42  is aimed to direct a jet of air toward the internal surfaces of outlet duct  55  and spout  39 . In the simple example of  FIG. 1 , only a single, relatively small round vent  42  is shown, but the shape, size, and placement of the air vent or vents  42  can have any number of forms. 
   A symbolically shown purge controller  35  operates air valve  28  through a linkage  52 . When linkage  52  is shifted to a first position by controller  35 , air valve  28  opens and compressed air flows to duct  31  and vent  42 . When controller  35  shifts linkage  52  to a second position, air valve  28  closes. 
   A link element  50  senses the position of lever  45  to communicate the setting of fuel valve  25  to purge controller  35 . Purge controller  35  acts to open air valve  28  during a time interval upon sensing each closing of fuel valve  25 . Purge controller  35  can use other means to sense closings of fuel valve  25  as well, such as directly monitoring fuel flow stoppage. 
   Purge controller  35  will typically comprise a tinier mechanism that operates to hold air valve  28  open for a preselected time interval. The timer mechanism can have a number of different structures and may be electronic or mechanical. Purge controller  35  is activated each time valve  25  is closed by releasing lever  45 , to provide for a period of time, a flow of air through duct  31  and vent  42 . 
     FIGS. 2   a ,  2   b , and  2   c  are related schematics showing different operating phases of a functional mechanical version of a timer device usable as purge controller  35 . This design includes a pair of air valves  28   a  and  28   b  connected in series to control flow of air from duct  18  to duct  31  and that together with the duct connecting them form valve  28  of FIG.  1 . Most certainly, the purging process can be controlled electronically where electrical power is available to nozzle  10 . And perhaps, better mechanical purge controllers can be devised as well. 
     FIG. 2   a  shows controller  35  and valves  28   a  and  28   b  in a rest state where valve  25  is closed and the purging operation complete for the last time valve  25  was open.  FIG. 2   b  shows controller  35  and valves  28   a  and  28   b  in a flow state where valve  25  is open.  FIG. 2   c  shows controller  35  and valves  28   a  and  28   b  in a purge state existing immediately after valve  25  has closed. All of these elements comprising purge controller  35  are mounted within and attached to various parts of the housing generally designated as  12 ′. 
   In this simple design, valve  28   a  has a control element  52   a  that opens valve  28   a  when shifted to the left as symbolized by the “O” on the left-pointing arrowhead. Valve  28   a  closes when the control element  52   a  is shifted to the right, as shown by the right-pointing arrow labeled “C”. 
   Valve  28   b  has a control element  52   b  that closes valve  28   b  when shifted to the left as symbolized by the “C” on the left-pointing arrowhead. Valve  28   b  opens when the control element  52   b  is shifted to the right, as shown by the right-pointing arrow labeled “O”. 
   The purge time is controlled by an extension spring  70  and a dashpot  75  connected in parallel between a portion  12 ′ of housing  12  and a guide or carrier  73 . Spring  70  and dashpot  75  form a timer element similar in function to the well-known screen door closers, although smaller in size and designed for handling much smaller forces. 
   Dashpot  75  has a piston or plunger that translates within a cylinder. Air flows slowly from the cylinder when the piston is pushed rightward creating substantial mechanical resistance to rightward movement. The piston provides little or no resistance to movement in the leftward direction. A check valve of some sort (not shown) provides this force difference. 
   Spring  70  is pretensioned to constantly provide force urging carrier  73  rightward. Spring  70  may be of the type providing linearly increasing force in response to extension as carrier  73  shifts to the left. 
   Carrier  73  translates along a straight line path as shown by the adjacent double ended arrow. The small circles beneath carrier  73  simply suggest rolling of carrier  73  on a flat surface. More often, carrier  73  will comprise a shaft sliding in a track or guideway. We chose the symbology shown for easier understanding. Carrier  73  is pulled to the left by linkage element  50  against the force of spring  70 . Thus, carrier  73  and linkage element  50  cooperate with dashpot  75  and spring  70  to control the position of valve control elements  52   a  and  52   b.    
   The position of carrier  73  is controlled to all intents and purposes by force applied by link  49  to linkage element  50 , and by force from dashpot  75  and spring  70  only. That is, any effects of valves  28   a  and  28   b  on the position of carrier  73  can be ignored. 
   In  FIGS. 1 and 2   a , link  49  holds valve  25  shut. In this state, valve  28   a  is closed and valve  28   b  is open, as indicated by the “C” and “0” near them. Air cannot flow from duct  18  to duct  31 . 
   Linkage element  50  is actuated leftward when link  49  rotates to the position opening fuel valve  25  as shown in  FIG. 2   b . Link  49  rotates on a pivot  48  shown symbolically as a small circle. Link  49  engages a tab or catch  51  to move linkage element  51  and carrier  73  to the left when link  49  is operated to the open position as shown in  FIG. 2   b . In transitioning to this position, carrier  73  simultaneously opens air valve  28   a  and closes air valve  28   b . Air still cannot flow from duct  18  to duct  31 . 
   When fuel flow stops, link  49  rotates clockwise from the position in  FIG. 2   b  to the position shown in  FIG. 2   c , opening valve  28   b , as indicated by the adjacent “O”. Valve  28   a  is also open and remains open for an interval whose length depends on the resistive force provided by dashpot  75  and the force from spring  70 . During this interval, compressed air flows from duct  18  to duct  31  and vent  42 , purging the downstream chamber of residual fuel. When the piston in dashpot  75  returns to the position in  FIG. 2   a  and valve  28   a  closes, the purge phase has ended. 
   The length one should chose for this time interval depends on a number of factors. At this point we have identified the following factors as important in determining the time interval to choose:
         1) finish on the internal surface of the downstream chamber;   2) type of material forming the internal surfaces of the downstream chamber;   3) volume and shape of the downstream chamber;   4) velocity and volume of air flowing from vent  42 ;   5) shape, number, and position of vent  42 ; and   6) type of fuel or other liquid.       

   Items  1 ,  2 , and  6  affect the amount of fuel clinging to the internal surfaces of the downstream chamber. Items  3 ,  4 , and  5  affect the efficiency of the purge operation. Of course, the interval length must be short enough so that the motorist will not have withdrawn spout  39  from the filler pipe before the purge operation is complete, typically less than 2 sec. As a practical matter, this aspect involves human engineering. 
   We expect that the air flowing from vent  42  will diffuse throughout the downstream chamber with a substantial velocity component directed toward outlet  58 . Fuel clinging to the internal surfaces of the downstream chamber will be flushed and purged by the moving air stream, and fall from outlet  58  and the air stream as the air velocity slows outside of the outlet  58 . 
   The volume of air is controlled for the most part by the supply pressure, pressure drops within the air or gas flow passages, and the area of vent  42 . These parameters should be adjusted to provide a total volume of atmospheric air or non-combustible gas preferably at least twice the total volume of the downstream chamber. Up to 4 times the total volume of the downstream chamber of compressed air or other gas should normally be adequate. 
   The finish and material of the interior surfaces in the downstream chamber affect the amount of fuel that adheres to these surfaces and ease with which it is removed by the airflow. Liquid fuels do not easily wet certain plastics. A smooth, shiny surface also is not as easily wet as a rough surface. 
     FIGS. 3 and 4  show one possible configuration for a compressed air vent  42 . In the side view of  FIG. 3 , compressed air from valve  28  flows through ducts  60  to a number of individual vents  63  spaced around an annular air guide  66 . The high speed air diffuses within guide  66  and purges the fuel adhering to the downstream surfaces out of outlet  58 . One may also design a shroud or guide that creates an annular vent, with the diffusion of the air velocity occurring further upstream. 
   While the embodiment shown places the spout purging components in nozzle  10 , one can envision other embodiments where the air valve  28  and purge controller  35  are in the system housing. Then the spout purging components in nozzle  10  may consist only of outlet pipe  31  and air vent  42 . 
   In this configuration, an air hose runs along the fuel delivery hose directly to outlet pipe  31  from the air valve  28  within the system housing. The sensing of the position of lever  45  may be done indirectly by sensing fuel flow. When fuel flow ceases, then purge controller  35  senses this condition and opens air valve  28 . Air then flows from a compressed air source to outlet pipe  31  and through vent  42 . 
   Once one shifts the location of the air flow control elements outside of nozzle  10 , then it is easy to use electrical devices to control airflow. In this case, purge controller  35  can be implemented electrically, using a microprocessor for example. Microprocessors can easily provide for precise timing of the purging airflow, triggering purging airflow when the fuel valve  28  closes and fuel flow ceases. 
   In another configuration nozzle  10  receives electrical power through the fuel delivery hose, in which case purge controller  35  may be located within housing  12 , but comprise electrical components and operate electrically. Even an air pump could be integrated into the nozzle  10 , possibly replacing air valve  28 . 
   Such a design could effectively eliminate the need for a system housing, and might have a display integrated with nozzle  10 . This display could show information in real time regarding the transaction. The nozzle  10  could also scan a credit card and provide information to a shared printer that provides a receipt for the transaction. 
   All of these variations as they apply to air purging of nozzles for delivery of liquids such as liquid fuel are intended to be included in the following claims.

Technology Category: b