Method for adjusting air to liquid ratio in vapor recovery system

An air to liquid regulator valve for use with a vapor recovery system that recovers vapors expelled from a vehicle receiving fuel through a fuel supply passage and returns the vapors to an underground storage tank through a vapor return passage in a service station environment. The regulator valve includes a housing defining a fuel flow path in fluid communication with the fuel supply passage and a vapor return path in fluid communication with the vapor return passage, a vapor return orifice defined by the housing and disposed between a first portion and a second portion of the vapor return path, and a vapor flow bypass in fluid communication with the first portion and the second portion of the vapor return path such that the flow of vapors through both the vapor flow bypass and the vapor return orifice is possible.

FIELD OF THE INVENTION

The present invention generally relates to the recovery of fuel vapors in connection with a liquid fuel dispensing facility. More particularly, the present invention relates to controlling the volume of fuel vapor recovered to ensure that the volume is in appropriate proportion to the volume of liquid fuel being dispensed.

BACKGROUND OF THE INVENTION

Liquid fuel dispensing facilities (i.e. gasoline stations) often suffer from a loss of fuel to the atmosphere due to inadequate vapor collection during fuel dispensing activities, excess liquid fuel evaporation in the containment tank system, and inadequate reclamation of the vapors during tanker truck deliveries. Lost vapor is an air pollution problem which is monitored and regulated by both the federal and state governments. Attempts to minimize losses to the atmosphere have been effected by various vapor recovery methods. Such methods include: “Stage-I vapor recovery” where vapors are returned from the underground fuel storage tank to the delivery truck; “Stage-II vapor recovery” where vapors are returned from a refueled vehicle tank to the underground storage tank; vapor processing where the fuel/air vapor mix from the underground storage tank is received and the vapor is liquefied and returned as liquid fuel to the underground storage tank; burning excess vapor off and venting the less polluting combustion products to the atmosphere; and other fuel/air mix separation methods.

When working properly, Stage-II vapor recovery results in equal exchanges of air or vapor (A) and liquid (L) between the main fuel storage tank and the consumer's gas tank. Ideally, Stage-II vapor recovery produces an A/L ratio very close to 1.0. In other words, returned vapor replaces an equal amount of liquid in the main fuel storage tank during refueling transactions. When the A/L ratio is close to 1.0, refueling vapors are collected, the ingress of fresh air into the storage tank is minimized, and the accumulation of an excess positive or negative pressure in the main fuel storage tank is prevented. This minimizes losses at the fuel dispensing nozzle and evaporation and leakage of excess vapors from the storage tank. Measurement of the A/L ratio thus provides an indication of proper Stage-II vapor collection operation. A low A/L ratio means that the proper amount of fuel vapor is not being recovered for the amount of fuel that has been dispensed.

The present invention recognizes and addresses considerations of prior art constructions and methods.

SUMMARY OF THE INVENTION

One embodiment of the present invention provides an air to liquid regulator valve for use with a vapor recovery system that recovers vapors expelled from a vehicle receiving fuel through a fuel supply passage and returns the vapors to an underground storage tank through a vapor return passage in a service station environment. The regulator valve includes a housing defining a fuel flow path in fluid communication with the fuel supply passage and a vapor return path in fluid communication with the vapor return passage, a vapor return orifice defined by the housing and disposed between a first portion and a second portion of the vapor return path, and a vapor flow bypass in fluid communication with the first portion and the second portion of the vapor return path such that the flow of vapors through both the vapor flow bypass and the vapor return orifice is possible.

Another embodiment of the present invention provides a vapor recovery system that recovers vapors expelled from a vehicle during refueling at a fuel dispensing point and returns the vapors to an underground storage tank in a service station environment, the system including an air to liquid regulator valve associated with the fuel dispensing point. The regulator valve includes a housing defining vapor return path, a vapor return orifice defined by the housing and disposed between a first portion and a second portion of the vapor return path, and a vapor flow bypass in fluid communication with the first portion and the second portion of the vapor return path such that the flow of vapors through both the vapor flow bypass and the vapor return orifice is possible. The system also includes a vapor pump that is in fluid communication with the underground storage tank, and a vapor flow passage that is in fluid communication with the vapor flow path of the air to liquid regulator valve and the vapor pump.

Yet another embodiment of the present invention provides an air to liquid regulator valve for use with a vapor recovery system that recovers vapors expelled from a vehicle receiving fuel through a fuel supply passage and returns the vapors to an underground storage tank through a vapor return passage in a service station environment. The regulator valve includes a housing defining a fuel flow path in fluid communication with the fuel supply passage and a vapor return path in fluid communication with the vapor return passage, a vapor return orifice defined by the housing and disposed between a first portion and a second portion of the vapor return path, and a vapor piston including a metering element, wherein the metering element is insertable into the vapor return orifice to regulate the flow of vapors therethrough, and the metering element is configured to prevent the flow of vapors through the vapor return orifice when the metering element is fully seated in the vapor return orifice. A vapor flow bypass is in fluid communication with the first portion and the second portion of the vapor return path such that the flow of vapors through the vapor flow bypass is possible when the metering nose prevents the flow of vapors through the vapor return orifice. A first flow adjustment mechanism selectively adjusts the vapor flow bypass such that an amount of vapor that is allowed to bypass the vapor return orifice during a fueling operation is adjustable.

Other objects, features and aspects for the present invention are discussed in greater detail below. The accompanying drawings are incorporated in and constitute a part of this specification, and illustrate one or more embodiments of the invention. These drawings, together with the description, serve to explain the principles of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A first embodiment of the present invention is described in connection withFIG. 1, which shows a vapor recovery system for use in a liquid fuel dispensing facility10, in accordance with the present invention. As shown, the fuel dispensing facility10includes a station house100, one or more fuel dispenser units200aand200b(fuel dispenser unit200bis not shown), a main fuel storage system300, means for connecting the fuel dispenser units200aand200bto the main fuel storage system300, and one or more vapor (or air) flow sensors (AFS's)501. The fuel dispenser units200aand200bmay be the ENCORE® sold by Gilbarco, inc. of Greensboro, N.C., or other fuel dispenser, such as that disclosed in U.S. Pat. No. 4,978,029, which is hereby incorporated by reference in its entirety.

As illustrated inFIG. 1, the station house100includes a central electronic control system110that includes a dispenser controller120(also known as a site controller or point-of-sale system), dispenser current loop interface wiring130connecting the dispenser controller120with the fuel dispenser unit(s)200aand200b, and a data acquisition system140. The dispenser controller120controls the fuel dispenser units200aand200band processes transaction information received from the dispensers200over the current loop130. The dispenser controller120is in electrical communication with the data acquisition system140, such as by a first wiring bus122. The interface wiring130may be electrically connected to the data acquisition system140by a second wiring bus132. The dispenser controller120may be the Gilbarco G-Site® or Passport® point-of-sale system.

The data acquisition system140preferably includes standard computer storage and central processing capabilities, keyboard input device(s), and audio and visual output interfaces among other conventional features. Entities such as the California Air Resources Board (CARB) have produced requirements for Enhanced Vapor Recovery (EVR) equipment. These include stringent vapor recovery system monitoring requirements to determine continuously whether or not the systems are working properly. In locations subject to these enhanced requirements, the data acquisition system140may also function as an in-station diagnostic monitor. For example, where required, the data acquisition system140may be the Veeder-Root Company TLS-350™ tank monitor. Both the dispenser controller120and the data acquisition system140may be further communicatively coupled to an off-site or remote system (not shown) for communicating information and receiving instructions remotely, in which case both systems may communicate with the remote system over telephone lines or other network lines, including the Internet.

Referring additionally toFIGS. 2 and 3, the fuel dispenser units200aand200bmay be provided in the form of conventional “gas pumps.” Each of the fuel dispenser units200aand200bmay include one or more fuel dispensing points typically defined by nozzles210. In the preferred embodiment shown, the fuel nozzles210are suitable vapor recovery nozzles used in combination with a mechanical air to liquid vapor regulator valve500(hereafter A/L regulator valve), such as that shown inFIGS. 7,8A and8B. The operation of the A/L regulator valve500is discussed in greater detail below.

Each fuel dispensing point of the fuel dispenser units200aand200bincludes a blend manifold260, a coaxial vapor/liquid splitter261, a vapor return passage220, a fuel supply passage230and the mechanical A/L regulator valve500. As shown, the mechanical A/L regulator valve500is preferably disposed adjacent the coaxial vapor/liquid splitter261. The vapor return passages220may be joined together before connecting with a common vapor return pipe410(FIG. 1).

The fuel dispenser units200aand200balso include liquid fuel dispensing meters240. The liquid fuel dispensing meters240provide dispensed liquid fuel quantity information to the dispenser controller120via a liquid fuel dispensing meter interface270, or control system, and interface wiring130. The control system270may be a microcontroller, a microprocessor, or other electronics with associated memory and software programs running thereon. The control system270typically controls aspects of the fuel dispenser units200aand200b, such as a gallons (or liters) display215, a price display216, receipt of payment transactions, and the like, based on fuel flow information received from the liquid fuel dispensing meters240.

The main fuel storage system300includes one or more main fuel storage tanks310aand310b. The fuel storage tanks310aand310bare typically provided underground, however, underground placement of the tank is not required for application of the invention. As best seen inFIG. 1, each fuel storage tank310aand310bis connected to the atmosphere by a vent pipe320. The vent pipe320terminates in a pressure relief valve330. A vapor processor340may be connected to the vent pipe320intermediate of the fuel storage tanks310aand310band the pressure relief valve330. Note, a vapor processor is not typically required in locations that are not subject to enhanced monitoring requirements. In this case, a pressure sensor350is operatively connected to the vent pipe320. The fuel storage tanks310aand310bmay also include an Automatic Tank Gauging System (ATGS)360used to provide information regarding the fuel level in the storage tanks. The vapor processor340, the pressure sensor350, and the automatic tank gauging system360are electrically connected to the data acquisition system140by third, fourth, and fifth wiring busses342,352, and362, respectively. The fuel storage tanks310aand310balso include a fill pipe and fill tube370to provide a means to fill the tanks with fuel and a submersible pump380to supply the dispensers200aand200bwith fuel from the storage tanks310aand310b.

The means for connecting the fuel dispenser units200aand200band the main fuel storage system300include a vapor return pipeline410and one or more fuel supply pipelines420. The vapor return pipeline410and the fuel supply pipelines420are connected to the vapor return passages220and fuel supply passages230, respectively, associated with multiple fuel dispensing points210. Fuel supply pipelines420may be double-walled pipes having secondary containment, as is well known. An exemplary underground fuel delivery system is illustrated in U.S. Pat. No. 6,435,204, which is hereby incorporated by reference in its entirety.

In the embodiment illustrated inFIG. 1, a variable speed vapor pump250driven by a motor252is coupled to the plurality of vapor return passages220by way of the common vapor return pipeline410to assist in the recovery of fuel vapor. In the preferred embodiment shown, variable speed vapor pump250may be the Healy VP1200®. An example of this system is found in U.S. Pat. No. 5,040,577, incorporated herein by reference in its entirety. The data acquisition system140receives information regarding the pressure in vapor return pipeline410from a pressure sensor253that is disposed on the inlet side of vapor pump250and electrically connected to the data acquisition system140by interface wire257.

As shown inFIG. 1, an AFS501is deployed in a common branch of the vapor return passages220to measure the vapor flows of various groupings of fuel dispensing points210, down to a minimum of only two dispensing point vapor flows. The latter example is realized by installing one AFS501in each of the fuel dispenser units200aand200b, which typically contains two dispensing points210(one dispensing point per dispenser side), as shown, or up to six dispensing points in MultiProduct Dispensers (MPD's) (3 per side). The vapor flows piped through the vapor return passage220are combined to pass through the single AFS501in the dispenser housing. However, alternate embodiments can include an AFS501that is dedicated to each individual fuel dispensing point210such that each AFS501measures the vapor flow from an individual fuel dispensing point210. Note, air flow sensors are not typically required in locations that are not subject to enhanced monitoring requirements.

Referring additionally toFIG. 3, the internal fuel flow components of one example of the present invention are illustrated. As previously noted, fuel travels from one or more of underground fuel storage tanks310aand310bby way of fuel supply pipelines420associated with their respective underground storage tank. The fuel supply pipelines420pass into the housing202of the fuel dispenser unit200athrough shear valves421(FIG. 2). The shear valves421are designed to cut off fuel flowing through their respective fuel supply pipelines420if the fuel dispenser unit200is impacted, as is commonly known in the industry. An exemplary embodiment of a shear valve is disclosed in U.S. Pat. No. 6,575,206, which is hereby incorporated by reference in its entirety. Similarly, vapor return passage220passes out of the fuel dispenser unit200athrough a shear valve221(FIG. 2).

As shown inFIG. 3, the fuel flow paths from the underground fuel storage tanks310aand310bto the fuel nozzle210each include a fuel filter246and a proportional valve244positioned along the fuel line230upstream of the liquid fuel dispensing meter240. Alternatively, the proportional valve244may be positioned downstream of the liquid fuel dispensing meter240. The liquid fuel dispensing meter240and the proportional valve244are positioned in a fuel handling compartment203of the housing202. The fuel handling compartment203is isolated from an electronics compartment located above a vapor barrier205. The fuel handling compartment203is isolated from sparks or other events that may cause combustion of fuel vapors, as is well understood and as is described in U.S. Pat. No. 5,717,564, which is hereby incorporated by reference in its entirety.

The liquid fuel dispensing meter240communicates through the vapor barrier205via a pulser signal line from pulser241to the control system270. The control system270regulates the proportional valve244, via a valve communication line, to open and close during fueling operations. The proportional valve244may be a proportional solenoid controlled valve, such as described in U.S. Pat. No. 5,954,080, which is incorporated herein by reference in its entirety. As the control system270directs the proportional valve244to open to allow increased fuel flow, the fuel enters the proportional valve244and exists into the liquid fuel dispenser meter240. The flow rate of the displaced volume of the fuel is measured by the liquid fuel dispenser meter240which communicates the flow rate of the displaced volume of fuel to the control system270via the pulser signal line. A pulse signal is generated on the pulser signal line in the example illustrated, such as by a Hall-effect sensor as described in U.S. Pat. No. 7,028,561, which is incorporated herein by reference in its entirety. In this manner, the control system270uses the pulser signal from the pulser signal line to determine the flow rate of fuel flowing through the fuel dispenser unit200aand being delivered to the vehicle12. The control system270updates the total gallons dispensed on the gallons display215via a gallons display communication line, as well as the cost of fuel dispensed on the price display216via a price display communication line.

As fuel leaves the liquid fuel dispensing meter240, the fuel enters a flow switch242. The flow switch242generates a flow switch communication signal via a flow switch signal line to the control system270to communicate when fuel is flowing through liquid fuel dispensing meter240. The flow switch communication signal indicates to the control system270that fuel is actually flowing in the fuel delivery path and that subsequent pulser signals from liquid fuel dispensing meter240are due to actual fuel flow.

After the fuel enters the flow switch242, it exits through the fuel supply passage230to be delivered to the blend manifold260. The blend manifold260receives fuels of varying octane values from the various underground fuel storage tanks310aand310band ensures that fuel of the octane level selected by the consumer is delivered to the consumer's vehicle12. After flowing through the blend manifold260, the fuel passes through the fuel hose212and fuel nozzle210for delivery into the fuel tank24of the vehicle12. Flexible fuel hose212includes a product delivery line231and the vapor return passage220. Both lines231and220are fluidly connected to the underground fuel storage tanks310aand310bthrough the fuel dispenser unit200a, as previously discussed. The vapor return passage220is separated from the product delivery line231by the coaxial vapor/liquid splitter261.

During delivery of fuel into the vehicle's fuel tank24, the incoming fuel displaces air in the fuel tank24containing fuel vapors. Vapor is recovered from the fuel tank24of the vehicle12through the vapor return passage220with the assistance of the vapor pump250. As previously noted, the vapor pump250of the present embodiment is a variable speed pump. As fuel is dispensed from the fuel nozzle210into the fuel tank24of the vehicle12, the flowing fuel causes the mechanical A/L regulator valve500to open, thereby opening the vapor return passage220to the fuel tank24.

More specifically, referring additionally toFIGS. 7,8A and8B, the A/L regulator valve500includes a liquid piston510, a vapor piston520, a vapor tube530, and a spring540, all of which are received within housing550. Additionally, the A/L regulator valve500includes a high flow adjustment mechanism560and a low flow adjusting mechanism580for adjusting the amount of recovered vapor for a given amount of fuel dispensed, as discussed in greater detail below. As best seen inFIGS. 8A and 8B, housing550defines a vapor flow path552along its longitudinal center axis that includes a vapor return orifice554at its terminal end. Additionally, the housing550defines a fuel flow path556that is substantially cylindrical in shape and concentric about the vapor flow path552. The housing550is configured such that the vapor flow path552is in fluid communication with the vapor return passage220and the fuel flow path556is in fluid communication with the product delivery line231of flexible fuel hose212(FIG. 2).

The vapor tube530includes a first end532, a second end534and a cylindrical portion536extending therebetween. The first end532of the vapor tube530is received concentrically within the housing550about the vapor flow path552and the vapor return orifice554. In this embodiment, the vapor tube530is retained within the housing550by an annular lip537formed about the second end534of the vapor tube530that interacts with an annular groove538formed about the inner surface of the housing550. The cylindrical portion536of the vapor tube530thus forms a portion of the vapor return path552.

The vapor piston520includes a metering element, or nose522, and a magnet524that are disposed on a shuttle body526. The vapor piston520is slidably received within the cylindrical portion536of vapor tube530such that back and forth motion of the vapor piston520within the vapor tube530causes the metering nose522to regulate the flow of fuel vapor through the vapor return orifice554.

The liquid piston510includes a magnet512and is slidably mounted along the outer surface of the vapor tube530. The spring540is also mounted about the outer surface of the vapor tube520and is arranged such that the liquid piston510is urged into the closed position (FIG. 8A). Similarly, interaction of the magnet512of the liquid piston510with the magnet524of the vapor piston520ensures that when the liquid piston510is in the closed position, the metering nose522of the vapor piston520is fully seated in the vapor return orifice554.

The high flow adjustment mechanism560includes a high flow adjustment screw562that is rotationally received in a first bore558defined by the housing550. The high flow adjustment screw562includes a head564that is received in a smooth portion of the first bore558and a threaded shank566that is received in a correspondingly threaded portion of the first bore558. As such, rotation of the high flow adjustment screw562causes the high flow adjustment screw562to move along the longitudinal axis of the first bore558, thereby causing a distal end568of the treaded shank566to either project farther into, or be withdrawn from, the vapor return path552. In this manner, the high flow adjustment screw562can be used to adjust the amount of vapor recovered for a given amount of fuel that is dispensed at a given rate, as discussed in greater detail below.

The low flow adjustment mechanism580includes a low flow adjustment screw582that is rotationally received in a second bore559defined by the housing550, and a vapor flow bypass590that is in fluid communication with both the portion of the vapor flow path552both upstream and downstream of vapor return orifice554. The low flow adjustment screw582includes a head584that is received in a smooth portion of the second bore559and a threaded shank586that is received in a correspondingly threaded portion of the second bore559. As such, rotation of the low flow adjustment screw582within the second bore559causes the low flow adjustment screw582to move along the longitudinal axis of the second bore559, thereby causing a distal end588of the threaded shank586to either project farther into, or be withdrawn from, the vapor flow bypass590. In this manner, the low flow adjustment screw582can be used to adjust the amount of vapor that is allowed to bypass the vapor return orifice554during fueling operations. Note, the distal end588of the low flow adjustment screw582can be fully seated within a portion of the vapor flow bypass590such that the flow of vapor through the vapor flow bypass590is prevented.

In use, a user activates the fuel nozzle210causing pressurized fuel to enter the fuel flow path556of the A/L regulator valve500, as discussed above. As best seen inFIG. 7A, the pressurized fuel acts against the surface area of a first end514of the liquid piston510, in opposition to the biasing force of the spring540. Eventually, the force exerted by the fuel causes the liquid piston510to slide along the outer surface of the cylindrical portion536of the vapor tube530against the biasing force of the spring540, thereby opening the fuel flow path556and allowing fuel to flow into the vehicle's fuel tank24. As the liquid piston510slides along the vapor tube530, the vapor piston520similarly slides along the inner surface of the cylindrical portion536of the vapor tube530due to interaction of the magnet524of the vapor piston520with the magnet512of the liquid piston510. As such, the metering nose522of the vapor piston520is withdrawn from the vapor return orifice554and the vapor flow path552is now open to the interior volume of the vehicle's fuel tank24, as shown inFIG. 7B.

The vacuum maintained by the vapor pump250causes the vapor laden air that is displaced by the ingress of fuel into the fuel tank24to be drawn through the A/L regulator valve500into the vapor return passage220. As noted above, as the rate at which fuel is dispensed increases, the vapor piston of the A/L regulator valve500opens further and more air is drawn into the vapor return passage220and associated vapor return pipeline410.

Testing reveals that the disclosed system functions as desired when a vacuum level as low as 80 mBar is maintained on the downstream side of the A/L regulator valves500. However, it is possible for small amounts of fuel to be drawn into the vapor return passages220through the associated nozzles210during vapor recovery. This fuel tends to collect in the lowest portion of the associated vapor return passage220, thereby effectively blocking the vapor return passage220and preventing further vapor recovery if the fuel is not cleared. Although proper vapor recovery is achieved through clear vapor return passages220when an 80 mBar vacuum is maintained, an 80 mBar vacuum is typically not great enough to ensure that any ingested fuel is further drawn through the vapor pump250so that the vapor return passages220remain clear and the recovery of vapor is continuous. As such, preferably, a vacuum of about 200 mBar may be maintained on the downstream side of the A/L regulator valves500in the present embodiment. Note, higher vacuum levels can also be used as long as they are adequate for maintaining the vapor return passages220in an unobstructed condition.

FIGS. 9A and 9Bare graphical representations of how the high flow adjustment mechanism560and the low flow adjustment mechanism580can be used, either alone or in combination, to adjust the amount of vapor that is recovered for a given amount of fuel that is dispensed, thereby adjusting the A/L ratio for the related A/L regulator valve500. Referring first toFIG. 9A, the use of the high flow adjustment mechanism560is discussed. For the exemplary embodiment shown, graph line600shows an initial setting for the high flow adjustment mechanism560and the low flow adjustment mechanism580in which the desired A/L ratio of 1:1 is achieved when fuel is being dispensed at the rate of 40 liters per minute.FIGS. 8A and 8Bshow a possible configuration of the A/L regulator valve500to achieve this A/L ratio in which the high flow adjustment screw562extends partially into the vapor flow path552and the low flow adjustment screw582extends partially into the vapor flow bypass590, thereby partially restricting vapor flow. The desired initial setting for the A/L regulator valve500, an A/L ratio of 1:1, is achieved by first providing a “rough” adjustment to the A/L ratio with the high flow adjustment mechanism560, and then fine tuning the setting of the A/L regulator valve500with the low flow adjustment mechanism580.

In the present example, graph line600reveals that for the desired initial setting, the A/L ratio of 1:1 is maintained across a substantial portion of the operating range of the associated fuel dispensing point210(FIG. 2). Note, however, that it may be necessary to adjust the A/L ratio at which a fuel dispensing point operates. One method of achieving varying A/L ratios for the A/L regulator valve500is reflected in graph lines610and620ofFIG. 9A. Graph line610reflects the results of extending the high flow adjustment screw562farther into the vapor flow path552than in its initial setting, thereby further restricting the flow of vapor through the vapor flow path552. The reduced slope of graph line610, when compared to the slope of graph line600, reflects the fact that less vapor is recovered for a given amount of fuel dispensed when compared to the initial setting of the high flow adjustment screw562, at which the A/L ratio of 1:1 was achieved.

Similarly, the amount of vapor that is recovered for a given amount of fuel that is dispensed can be increased by withdrawing the high flow adjustment screw562farther from the vapor flow path552than in its initial setting, thereby reducing the restriction to the flow of vapor through the vapor flow path552. The increased slope of graph line620, when compared to the slope of graph line600, reflects the fact that more vapor is recovered for a given amount of fuel dispensed when compared to the initial setting of the high flow adjustment screw562.

However, the reduced slope and increased slope of graph lines610and620, respectively, as compared to the slope of the graph line600of the initial setting, reflect the fact that as the rate at which fuel is being dispensed decreases, the high flow adjustment mechanism560becomes less efficient with regard to adjusting the amount of vapor recovered relative to the amount of fuel being dispensed. More specifically, for the preferred embodiment discussed, a vapor flow adjustment of 10 liters per minute at a fuel dispensing rate of 40 liters per minute results in a corresponding change of approximately 1 liter per minute vapor flow at the reduced fuel flow rate of 20 liters per minute. The low flow adjustment mechanism580facilitates the adjustment of recovered vapor amounts across the full spectrum of fuel dispensing rates.

Referring additionally toFIG. 9B, the use of the low flow adjustment mechanism580is discussed. The low flow adjustment mechanism580can be used alone or in combination with the high flow adjustment mechanism560.FIG. 9Bincludes graph lines600,610and620that were previously discussed with regard toFIG. 9A, but are repeated here to facilitate the discussion of how the low flow adjustment mechanism580can be used to adjust the amount of vapor recovered. As previously noted, for the exemplary embodiment shown, graph line600shows an initial setting for the high flow adjustment mechanism560and the low flow adjustment mechanism580in which the desired A/L ratio of 1:1 is achieved across a substantial portion of the operating range of the A/L regulator valve500.

One method of varying the A/L ratios for the A/L regulator valve500is reflected in graph lines602and612ofFIG. 9B. Graph line602reflects the results of withdrawing the low flow adjustment screw582farther from the vapor flow bypass590than in its initial setting, thereby reducing the restriction to the flow of vapor through the vapor flow bypass590. Note, however, the slope of graph line602is substantially the same as that of graph line600. The substantially similar slopes of graph lines600and602reflect the fact that the increased amount of vapor recovered is substantially the same across the full range of rates at which fuel can be dispensed.

Similarly, the amount of vapor that is recovered for a given amount of dispensed fuel can be reduced by extending the low flow adjustment screw582farther into the vapor flow bypass590than in its initial setting, thereby further restricting the flow of vapor through the vapor flow bypass590. Note, the “starting point” for the adjustment of the low flow adjustment screw582represented by graph line612is graph line610, meaning prior to adjusting the low flow adjustment screw582, the high flow adjustment screw562had been previously adjusted from the initial setting as discussed with regard toFIG. 8A. The similar slopes of graph lines610and612reflect the fact that less vapor is recovered across substantially the full range of rates at which fuel is dispensed. Graph lines602and612show the results of adjusting only the low flow adjustment screw582after the desired slope of the graph line has been achieved using the high flow adjustment screw562.

Referring now to graph line622ofFIG. 9B, simultaneous adjustment of both the high flow adjustment mechanism560and the low flow adjustment mechanism580is discussed. Graph line622is achieved when starting from graph line600which shows the initial setting of an A/L ratio of 1:1 by adjusting both the high flow adjustment screw562and the low flow adjustment screw582. For example, extending the high flow adjustment screw562farther into the vapor flow path552restricts the flow of vapor through the vapor flow path552, thereby reducing the slope of graph line622as compared to the slope of graph line600. Next, the low flow adjustment screw582is withdrawn farther from the vapor flow bypass590than in its initial setting. This results in an increased amount of vapor being recovered across the full spectrum of rates at which fuel is dispensed, in effect, causing the entire graph line622to move upwardly while maintaining the substantially same slope that was achieved by adjusting the high flow adjusting screw562. The net result for the present example is that a greater amount of vapor flow is recovered at reduced fuel dispensing rates, such as 15 liters per minute, whereas a lesser amount of vapor is recovered at increased fuel dispensing rates, such as 35 liters per minute, when compared to the graph line600of the initial setting. As such, combined usage of the high flow adjustment mechanism560and the low flow adjustment mechanism580can achieve numerous A/L ratios across the entire operating range of the associated fuel dispensing unit.

Although the embodiment of the A/L regulator valve500shown inFIGS. 8A and 8Bincludes a vapor flow bypass590with a low flow adjustment screw582to adjust flow therethrough, other embodiments of the A/L regulator valve500that are encompassed by the current invention can use alternate arrangements to effect similar results. For example, varying the amount of vapor recovered for a given amount of fuel dispensed can be achieved by altering the metering nose position relative to the vapor piston body, adjusting the position of the vapor flow orifice axially within the vapor flow path of the housing with a mechanism such as a worm drive, varying the spring force that biases the liquid piston into the closed position, altering the position of the magnet on the liquid piston, and varying the size of the vapor flow orifice by use of a collet-type device.

A second embodiment of the present invention is shown inFIGS. 4 and 5. The second embodiment differs primarily from the first embodiment in that each fuel dispenser unit200aand200bincludes a dedicated vapor pump250for the recovery of fuel vapors rather than a single vapor pump250that is disposed in the common vapor return pipeline410and services multiple fuel dispenser units. As shown, the inlet side of vapor pump250is common to both vapor return passages220of fuel dispenser unit200aand the outlet side exhausts to the common vapor return pipeline410. As such, it is the vacuum levels of the vapor return passages220within each fuel dispenser unit200aand200bthat are monitored rather than the vacuum level within the vapor return pipeline410. Therefore, pressure sensor253is positioned on the inlet side of the vapor pump250rather than on the vapor return pipeline410. An additional difference of the second embodiment is that the control system270of each fuel dispenser unit200aand200bcontrols the operation of its dedicated vapor pump250rather than the central data acquisition system140.

A third embodiment of the present invention is shown inFIG. 6. The third embodiment is similar to the second embodiment in that each fuel dispenser unit200aand200bincludes a dedicated vapor pump250for the recovery of fuel vapors. As shown, the inlet side of vapor pump250is common to both vapor return passages220of fuel dispenser unit200aand the outlet side exhausts to the common vapor return pipeline410. As such, it is the vacuum levels of the vapor return passages220within each fuel dispenser unit200aand200bthat are monitored rather than the vacuum level within the vapor return pipeline410. Similarly to the second embodiment of the present invention, in the present embodiment the control system270of each fuel dispenser unit200aand200bcontrols the operation of its dedicated vapor pump250.

An alternate embodiment of the present invention differs from the first three embodiments in that each fuel dispenser unit200aand200bincludes a pair of dedicated vapor pumps250for the recovery of fuel vapors rather than a vapor pump250that is disposed in the common vapor return pipeline410, as shown inFIG. 1, or a common vapor return passage220, as shown inFIGS. 4 and 6, such that the pump services multiple fuel dispensing points. In this embodiment, the inlet side of each vapor pump250is a vapor return passage220of a single fuel nozzle210and the outlet side of each vapor pump250exhausts to a common portion of the vapor return passages220. As such, it is the vacuum level of the individual vapor return passages220within each fuel dispenser unit200aand200bthat is monitored, rather than the vacuum level within the common vapor return pipeline410or a vapor return passage220that is common to more than one fuel nozzle210.

Each of the previously discussed embodiments disclose a vapor recovery system including one or more variable speed vapor pumps. Note, however, that in each of the previously discussed embodiments, the variable speed vapor pumps can be replaced with fixed speed pumps. Additionally, electronic proportional valves (not shown) can be disposed on the upstream side of the various fixed speed pumps.

As discussed above, the control system270receives information from liquid fuel dispensing meter240and the pulser241regarding the amount of fuel being dispensed. The liquid fuel dispensing meter240measures the fuel being dispensed while the pulser241generates a pulse per count of liquid fuel dispensing meter240. In an exemplary embodiment, the pulser241generates one thousand and twenty-four (1024) pulses per gallon of fuel dispensed. In yet another alternate embodiment of the present invention, the control system270provides fuel flow information to the data acquisition system140by way of the interface wiring130. In this embodiment, the rate at which vapor pump250is used to recover vapor is determined by the amount of fuel the data acquisition system140determines is being dispensed, based on the information provided by the liquid fuel dispensing meters240via interface wiring130. The vapor pump250may be a variable speed pump or a constant speed pump with an electronic proportional valve, a mechanical pressure regulator operating across its inlet and outlet, etc., as previously discussed.

While preferred embodiments of the invention have been shown and described, modifications and variations thereto may be practiced by those of ordinary skill in the art without departing from the spirit and scope of the present invention, which is more particularly set forth in the appended claims. In addition, it should be understood the aspects of the various embodiments may be interchanged without departing from the scope of the present invention. Furthermore, those of ordinary skill in the art will appreciate that the foregoing description is by way of example only, and is not intended to limit the invention as further described in such appended claims.