Patent Publication Number: US-6336479-B1

Title: Determining vapor recovery in a fueling system

Description:
FIELD OF THE INVENTION 
     The present invention is directed to a vapor recovery system and, more particularly, to a vapor recovery system having a valve positioned in the nozzle to assist in determining leaks along the vapor recovery system including the hanging hardware. 
     BACKGROUND OF THE INVENTION 
     Vapor recovery equipped fuel dispensers, particularly gasoline dispensers, have been known for quite some time, and have been mandatory in California for a number of years. The primary purpose of using a vapor recovery fuel dispenser is to retrieve or recover vapors that would otherwise be emitted to the atmosphere during a fueling operation, particularly for motor vehicles. The vapors of concern are generally those which are contained in the vehicle gas tank. As liquid gasoline is pumped into the tank, the vapor is displaced and forced out through the filler pipe. Other volatile hydrocarbon liquids raise similar issues. In addition to the need to recover vapors, some states, California in particular, are requiring extensive reports about the efficiency with which vapor is recovered and proof that the vapor recovery systems are working as intended. 
     A traditional vapor recovery apparatus is known as a “balance” system, in which a sheath or boot encircles the liquid fueling spout and connects by tubing back to a fuel reservoir. As the liquid enters the tank, the vapor is forced into the sheath and back toward the fuel reservoir or underground storage tank (UST) where the vapors can be stored or recondensed. Balance systems have numerous drawbacks, including cumbersomeness, difficulty of use, ineffectiveness when the seals are poorly made, and slow fueling rates. 
     As a dramatic step to improve on the balance systems, Gilbarco, Inc., assignee of the present invention, patented an improved vapor recovery system for fuel dispensers, as seen in U.S. Pat. No. 5,040,577, now Reissue Patent No. 35,238 to Pope, which is herein incorporated by reference in its entirety. The Pope patent discloses a vapor recovery apparatus having a vapor pump in the vapor return line driven by a variable speed motor. The liquid flow line includes a pulser, conventionally used for generating pulses indicative of the liquid fuel being pumped. This permits computation of the total sale and the display of the volume of liquid dispensed and the cost in a conventional display. A microprocessor translates the pulses indicative of the liquid flow rate into a desired vapor pump operating rate. The effect is to permit the vapor to be pumped at a rate correlated with the liquid flow rate so that, as liquid is pumped faster, vapor is also pumped faster. 
     Previous systems have been developed to test for leaks in the vapor recovery line. U.S. Pat. Nos. 5,450,883 and 5,857,500 both assigned to Gilbarco, Inc. and incorporated herein by reference in their entirety, disclose vacuum-assisted vapor recovery systems having vapor valves positioned within the vapor recovery line between the nozzle and vacuum pump and between the vapor pump and underground storage tank. Both systems include pressure sensors to detect leaks in the vapor recovery system, and may include a valve in the dispenser nozzle. However, the valves are manually operated requiring trained personnel or technicians to physically open and close the valves in the nozzle and check for leaks in the vapor recovery system. 
     SUMMARY OF THE INVENTION 
     The present invention allows for detecting a leak within a vapor recovery system, including the hanging hardware. A valve positioned in the vapor recovery line within the hanging hardware is selectively positionable between open and closed positions. In one embodiment, when the hanging hardware is in an upright, or vertical position such as when not in use, an attitude valve positioned in the nozzle is in a closed position. A vapor pump is positioned on the vapor recovery line downstream of the valve to create a vacuum within the line to draw vapors during the fueling process. A pressure sensor is also located on the vapor recovery line for detecting the amount of pressure within the line. A control system monitors the vapor pump and pressure sensor and compares the sensor readings with values stored in memory. A leak is detected when the detected pressure in the vapor recovery differs from the stored value. 
     The invention may further include additional valves positioned along the vapor recovery line. Each of the valves is operatively connected to the control system which positions each between open and closed orientations. Leaks in the vapor recovery system can be determined and isolated by testing individual sections of the vapor recovery line and comparing the values. In either embodiment, if the control system identifies a leak, the fueling system may be shut down, or a signal sent to a technician or user indicating the leak and that service is required. 
     A method of performing the testing along the portions of the vapor recovery line are also included within the invention. One method of testing includes using a single valve within the hanging hardware. When the valve is closed, the vapor pump is initiated and a pressure reading is obtained within the vapor recovery line. The pressure is compared to an expected value previously stored in the control system and if the values differ, a leak is determined to exist. 
     A second method uses the valve within the hanging hardware, and at least one additional valve placed along the vapor recovery line. A first pressure reading is performed by closing the additional valve and determining the vapor pressure within the line between the additional valve and the vapor pump. The additional valve is then opened, and the hanging hardware valve is closed to determine a second vapor pressure between the hanging hardware valve and the vapor pump. The first and second vapor pressures are compared to determine whether there are any leaks within the vapor recovery line. Additionally, the approximate location of the leak may be determined by comparing the vapor pressures from each section. If both sections indicate a leak, the leak is located at a point shared by both sections. Likewise, if only one section indicates a leak, the leak is located at a point not commonly shared by both sections. Notably, the systems and methods described above can be modified such that a vapor pump creates a positive pressure or a negative pressure in the vapor recovery line. 
     Another method closes one of the valves and creates a pressure within the vapor recovery line. The pressure, either positive or negative, is determined by the pressure sensor and then maintained for a period of time. Afterwards, the pressure is again tested and a leak within the vapor recovery line will result in a change in the pressure. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic view of a fuel dispenser incorporating a vapor recovery system; 
     FIG. 2A is a schematic illustration of a nozzle having an attitude valve in an open position; 
     FIG. 2B is a schematic illustration the nozzle of FIG. 2A in an upright position with the attitude valve closed; and 
     FIG. 3 is a schematic view of a preferred embodiment of a vapor recovery system of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In the following description, like reference characters designate like or corresponding parts throughout the Figures. Also, terms such as “forward”, “backward”, “left”, “right”, “upwardly”, “downwardly”, and the like are words of convenience and are not to be construed as limiting terms. Certain modifications and improvements will occur to those skilled in the art upon a reading of the following description. It should be understood that all such modifications and improvements have been deleted herein for the sake of conciseness and readability but are properly within the scope of the claims. 
     The present invention is directed to a vapor recovery system for a fuel dispenser having a valve positioned in the hanging hardware to assist in leak detection. Placement of the valve within the hanging hardware allows for the nozzle and/or delivery hose to be tested for leaks. The valve adjusts between open and closed orientations and additional vapor valves placed along the vapor recovery line allow for isolating sections to determine the position of any leaks. A pressure sensor positioned in the vapor recovery line determines the amount of pressure within the line. The pressure values are compared to determine if there is a leak within the line and the approximate position of the leak. The term “changing hardware” is understood to mean the parts of the vapor recovery line extending outside of the fuel dispenser housing, such as the delivery hose  14  and nozzle  16 . 
     Turning now to FIG. 1, a fuel dispenser  10  is adapted to deliver fuel, such as gasoline or diesel fuel, to a vehicle  12 . The fuel is stored in an underground storage tank (UST)  40  and is pumped by a fuel pump (not shown) through a fuel delivery line  36  to the nozzle  16 . Preferably, the vehicle  12  includes a fill neck  20  and a tank  22 , which accepts the fuel and provides it through appropriate fluid connections to the engine (not shown) of the vehicle  12 . 
     The nozzle  16  and delivery hose  14  include both the product delivery line  36  and a vapor return line  34  as illustrated in FIGS. 1,  2 A, and  2 B. Preferably, the spout  18  has the product delivery line  36  positioned within an inner section with the vapor recovery line  34  extending around the outer spout edge. The spout  18  may further include apertures (not shown) for capturing vapor emanating in the vehicle tank  22 . The product delivery line  36  and vapor recovery line  34  are further aligned within the delivery hose  14  preferably with the product line extending along an annular outer portion and the vapor line within an interior portion. The vapor recovery line  34  extends through the dispenser  10  and terminates in the UST  40 . The UST  40  may also be equipped with a vent shaft  42  and a vent valve  44 . During delivery of fuel into the vehicle tank  22 , and returning fuel vapor into the UST, air may be vented through the vent shaft  42  and valve  44  to equalize the pressure within the tank. 
     A housing  59  extends around the above ground section of a fuel dispenser as illustrated in FIG. 1 for protecting the fuel dispenser elements. Preferably, the only elements placed outside of the housing  59  are the delivery hose  14  and nozzle  16 . The housing  59  further includes a nozzle boot  57  for mounting the nozzle  16  when not in use. The nozzle  16  is maintained in an upright, vertical position while being stored in the boot  57 . 
     A valve  17  is positioned within the nozzle  16  for selectively opening and closing the vapor return line  34 . One embodiment features an attitude valve, as illustrated in FIGS. 2A and 2B, that automatically adjusts between opened and closed positions depending upon the orientation of the nozzle  16 . In one attitude valve embodiment, the attitude valve  17  includes a two-chamber orientation with a ball contained therein for selectively opening and closing the vapor return line depending upon the nozzle orientation as disclosed in U.S. Pat. No. 4,058,149, herein incorporated by reference in its entirety. 
     The attitude valve  17  maintains a closed position when the nozzle  16  is held or stored in a vertical position such as positioned on the dispenser boot  57 . When the nozzle  16  is in a horizontal position such as during the fueling process illustrated in FIGS. 1 and 2A, the attitude valve  17  is in an open position allowing for vapor recovery. The degree of tilt at which the attitude valve  17  opens and closes may vary and be adjusted for a variety of embodiments. In one embodiment, a tilt angle of greater than about forty-five degrees closes the attitude valve  17 . 
     Other valve designs are also available for opening and closing the vapor return line such as a solenoid valve, or a valve operated via RF signals. These other designs may not require the valve  17  to be in a particular orientation, but rather are positively controlled by a signal from the control system  50 , or other source. In one embodiment, the valve  17  is controlled by the control system  50  dependent upon the actuation of the fuel delivery system. The valve  17  is closed when the fuel delivery system is off and not pumping fuel through the product delivery line  36 , and opened when the dispenser is actuated. 
     Another embodiment includes a sensor  11  positioned adjacent to the boot  57  and in communication with the control system  50  to sense the placement of the nozzle  16  within the dispenser housing. The sensor  11  may also be a reed switch positioned within the dispenser boot  57  that is moved between on and off positions by the placement of the nozzle  16 . When the nozzle  16  is within the boot  57 , the control system  50  closes the valve  17 . Alternatively, when the nozzle  17  is away from the boot  57 , the valve  17  is open as it is assumed that vapor recovery is necessary. This assumption provides for vapor leak testing without a user or operator manually toggling the valve between an on and off position. Additional types of valves may include spring loaded valves, and electrically controlled valves. 
     Preferably, the valve  17  is positioned within the nozzle  16 . However, the valve  17  may also be positioned in other locations along the length of the delivery hose  14 . 
     A vapor pump  52  provides a vacuum for pulling vapor at the spout  18  into the vapor recovery line  34  and propelling the vapor into the underground storage tank  40 . The vapor pump  52  may additionally supply a vacuum or positive pressure in the vapor recovery line during testing to locate any possible leaks. Alternatively, a separate vapor pump (not shown) may be positioned along the vapor recovery line  34  for either supplying or removing air for testing purposes. 
     Vapor valves  51  may be positioned at various points in the vapor recovery line  34  for testing different sections of the line for leaks. Preferably, a second vapor valve  51  is located just upstream of the hanging hardware. Additional valves may also be positioned along the vapor recovery line  34  for isolating smaller sections of the line, as well as downstream of the vapor pump  52  such as valve  53  positioned in proximity to the underground storage tank  40 . 
     The vapor pump  52  and vapor valve  51  allows for three basic embodiments to control vapor flow during fueling operations. The first embodiment is a constant speed vapor pump with the vapor valve  51  being selectively positionable in either an open or closed position. The second embodiment is a vapor pump driven by a constant speed motor with vapor valve  51  selectively positionable at a variety of positions and adjusted to increase or decrease the flow of vapor. The third embodiment is a variable speed motor and pump in combination with valve  51  adjustable between either an open or closed alignment. One type of variable speed motor and pump is that described in U.S. Pat. No. 5,040,577, now reissue patent no. 35,238. 
     Connected between vapor valve  51  and vapor pump  52  is a pressure sensor  71 . Pressure sensor  71  measures the pressure in the vapor return line  34  between the vapor valve  51  and the vapor pump  52 . Other pressure sensors may also be positioned along the vapor return line  34 , such as an outlet pressure sensor  73  that measures the pressure between the vapor pump  62  and vapor valve  53 . 
     A control system  50  is connected to pressure sensors  71 , 73  through pressure signal input lines  81  and  83 , respectively as illustrated in FIG.  3 . The pressure signal input lines  81 , 83  allow pressure signals produced by pressure sensors  71 , 73  to be transmitted and input to the control system  50 . The pressure signals are processed and compared to stored reference pressure values to determine if an error condition exists in the vapor recovery system  10 , according to a routine controlled by the control system  50 . Instructions for the routine and data used in the routine may be stored in a conventional memory unit such as a ROM, PROM or flash memory accessible by the control system  50 . 
     The reference pressure values correspond to the pressure that should exist in the sections of the vapor recovery line  34  at the selected pump speed in the absence of either a leak in the line or a deficiency in the pump. The reference pressure values can be determined through empirical testing. A table of reference with pressure values corresponding to various pump speeds and vapor recovery line sections is stored in the control unit  50  to allow for testing at various pump speeds, vapor pump directions, and valve settings. Preferably, values exist for each of the various settings of the vapor pump  52  and the valves. Further, these may be positive or negative pressures depending upon the manner of leak testing. 
     Control system  50  is connected to the vapor valves  51 ,  53  through valve control lines  91 , 93 , respectively and to a motor  61  through control line  95 . Control system  50  actuates vapor valves  51 ,  53  and controls motor  61  to permit testing of the vapor recovery system  10 . 
     In use, a number of testing procedures are available for determining the existence of a leak within the vapor recovery system. A first testing procedure is performed with the hanging hardware valve  17  closed and the other valves upstream of the vapor pump  52  open. With an attitude valve, the control system  50  receives a signal from the sensor  11 , or other indication that the nozzle is positioned within the boot  57 . The control system  50  then signals the vapor pump  52  to operate at a predefined level. The pressure sensor  71  detects the pressure generated in the vapor recovery line  34  and signals the control system  50 . The control system  50  compares the received pressure values with those stored in memory. If the values are comparable, the control system  50  determines that no leaks exist and the vapor recovery system is operating effectively. If the measured values differ from those stored in memory, the control system recognizes a problem with the vapor recovery system and may shut down the fuel dispenser  10 , send a signal to an operator that a problem has occurred, or other like procedures. 
     The control system  50  may also allow for acceptable ranges of leakage. By way of example, if the measured values are within a predetermined percentage of the saved results, the control system  50  may allow for the fuel dispenser to remain operational, but send a message to an operator indicating that the vapor recovery system may be in need of service. Once the leakage level exceeds the predetermined percentage, the control system  50  could shut down the fuel dispenser  10 , notify a central office, or notify attendant personnel. 
     The values stored in memory may be periodically changed or updated. Initially, the values stored in the memory may correspond to optimal vapor pressures of a new or properly functioning vapor recovery system. Variables such as amount of operating time, weather conditions, etc., may change the efficiency of the vapor recovery system. After a period of use, the vapor recovery system may be serviced and recalibrated and the updated amounts entered into the memory and used for comparison purposes. 
     A second testing procedure requires comparing the pressure levels along different portions of the vapor recovery line  34 . A first test is performed with the vapor valve  51  closed, and the remainder of the downstream valves to the vapor pump  52  open. These registered values are monitored and stored within the control system  50 . A second test is then performed with the vapor valve  51  opened, and the valve  17  in the closed position. The second test values are determined and compared against the results of the first test. A leak detected in the first test indicates a vapor leak between the vapor valve  51  and vapor pump  52 . A leak detected in the second test indicates a leak between the valve  17  and the vapor valve  51 . The hanging hardware may be checked in this manner when the valve  17  is placed in the nozzle  16 , and the vapor valve  51  placed where the delivery hose  14  enters the dispenser housing  59 . 
     In a third testing procedure, a section of the vapor recovery line  34  is pressurized and maintained for a period of time to determine whether there are any leaks. A pressure, either positive or negative, is created within at least a portion of the vapor recovery line  34 . The pressure is then determined by the pressure sensor located along the portion of the vapor recovery line  34  and stored at the control system  50 . The pressure in the portion is maintained for a predetermined period of time, and the pressure is again determined and sent to the control system  50 . Changes in the pressure level between the first and second readings indicate the existence of a leak. 
     Additional valves may be placed along the vapor recovery line  34  for isolating sections for determining the position of an expected leak. Several testing procedures are discussed in U.S. Pat. Nos. 5,450,883 and 5,857,500. Those skilled in the art will recognize additional testing protocols using the valve positioned within the hanging hardware. 
     Testing may be performed at a variety of time instants. The control system  50  may be programmed to test at preset intervals. Alternatively, the testing may be initiated by a fueling station attendant or other personal and performed on an as-needed basis. Additionally, the test may be initiated from a remote, central office or may be initiated by a standards board or other like compliance organization. 
     A log file may be maintained within the control system  50  indicating the results of the pressure tests. The log file may also be maintained at a site controller or central controller.