FUEL DISPENSER

Abstract: A fuel dispenser having a filter status sensor includes a fuel delivery path; a fuel filter in the fuel delivery path; a flow monitor in the delivery path for measuring fuel flow in the delivery path; and a controller associated with the flow monitor adapted to determine and compare a first flow rate taken during a first cycle with a second flow rate taken during a second cycle. The controller provides a filter status signal when the first and second flow rates differ by more than a predetermined difference indicative of an unclean fuel filter.

Description: FUEL DISPENSER The present invention relates to fuel dispensers and fuel dispensing systems and, more particularly to such dispensers and systems having a fuel filter status sensor for detecting a clogged filter in a fuel delivery path of the fuel dispenser or dispensing system. Fuel dispensers use filters in the fuel delivery path to protect dispensers against harm from particles in the fuel and give customers a cleaner product. As fuel flows through the filter, particles in the fuel are continuously caught by the filter. Maximum obtainable delivery rates become reduced as the filter is loaded with entrapped debris resulting in a filter that is "unclean". Due to the many different conditions and environments found in the fuel dispensing industry, it has been impossible to set an absolute standard, based on time or volume of fuel delivered, at which to change the filter. Thus, there is a need in the fuel dispensing industry for a system capable of determining when a fuel filter needs to be changed which is not based on a fixed volume of fuel delivered or a set amount of time. Accordingly, the present invention provides a fuel dispenser having a filter status sensor comprising: a fuel delivery path: a fuel filter in the fuel delivery path: a flow monitor in the delivery path for measuring fuel flow in the delivery path; and a controller associated with the flow monitor adapted to determine and compare a first flow rate determined during a first cycle with a second flow rate determined during a second cycle and provide a filter status signal when the first and second flow rates differ by more than a predetermined amount. The provision of a filter status signal enables an operator to be alerted of the need to change the filter. The determination of filter status by monitoring flow rates over sequential cycles ensures that an operator is alerted as soon as, and only when, the filter becomes clogged. A problem with the previous systems, in which the filter is changed after a set amount of time or fuel delivered, is that the filter may be replaced unnecessarily soon or, conversely, after the fuel flow rate has dropped below unacceptable levels. Preferably, the first flow rate is a maximum flow rate occurring during the first cycle and the second flow rate is maximum flow rate occurring during the second cycle. If the second flow rate value from the second cycle is not lower than the first flow rate value of the first cycle by the predetermined amount, a third cycle begins in a similar fashion to the second cycle. Preferably, the third flow rate is a maximum flow rate value obtained during the third cycle. This value is compared with the first flow rate value obtained during the first cycle. The process will continue until a maximum flow rate value for a subsequent cycle is obtained which is less than the first maximum flow rate value by the predetermined amount. Preferably, the flow rates are stored in respective memory locations associated with the controller, the stored values being updated when the current flow rate exceeds the maximum flow rate stored in the respective memory locations. The memory locations may be shared or adjusted as desired by the programmer. For example, the third maximum flow rate may be stored in the memory location where the second maximum flow rates were stored, thereby saving memory. Each cycle may include a plurality of fuelling operations, a predetermined quantity of fuel, a predetermined amount of time or a predetermined number of transactions. When the cycles are defined by a predefined amount of fuel, it may be preferable to define the first cycle as being over 5,000 gallons (or 19,000 litres) and the second cycle as being less than that set for the first cycle. The predetermined amount of difference between the flow rates, which difference is indicative of an unclean filter may conveniently be set to two gallons, or seven litres, per minute. An embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which :- Figure 1 is a schematic representation of a fuel dispenser and dispensing environment constructed according to a preferred embodiment of the present invention; Figure 2 is a schematic of a controller and fuel delivery path constructed according to the embodiment of Figure 1 ; and Figures 3A-3D depict a flow chart outlining the operation of the preferred embodiment of the current invention. Referring to Figure 1 , in a typical service station, a vehicle 100 is shown being fuelled from a fuel dispenser 10. A spout 2 of nozzle 4 is shown inserted into a filler pipe 102 of a fuel tank 104 during the refuelling of the vehicle 100. A fuel delivery hose 6 is connected at one end to the nozzle 4, and at its other end to the fuel dispenser 10. In the case of a vapour recovery-equipped fuel dispenser, as shown by the cutaway view of the interior of the fuel delivery hose 6, a fuel delivery passageway 8 is formed within the fuel delivery hose 6 for distributing fuel pumped from an underground storage tank 12 to the nozzle 2. Fuel is typically pumped by a delivery pump system 16 located within tank 12. The fuel delivery passageway 8 is typically annular within the delivery hose 6 and tubular from within the fluid dispenser 10 to the tank 12. The fuel delivery hose 6 typically includes a tubular vapour recovery passageway 14 for transferring fuel vapours expelled from the vehicle's fuel tank 104 to the underground storage tank 12 during the refuelling of the vehicle 100. A vapour recovery pump 28 provides a vacuum in the vapour recovery passageway 14 for removing fuel vapour during a refuelling operation. The vapour recovery system using the pump 28 may be any suitable system such as those shown in U.S. Patent Nos. 5,040,577 to Pope, 5, 195,564 to Spalding, or 5,333,655 to Bergamini et al. In addition, the invention is useful on dispensers that are not vapour recovery dispensers. The fuel delivery passageway 8 includes a control valve 22, a positive displacement flow meter 24 and fuel filter 20. The fuel dispenser 10 also includes a control system 26, operatively associated with the control valve 22, flow meter 24 and the fuel pump 16. The control system 26 includes memory 30 (see Figure 2) for accessing and storing data and program information necessary for operation. In the preferred embodiment, the flow meter 24 drives a pulser (not shown) that provides a volume signal 34. Such meter/pulser devices have been used for years to show the volume of fuel dispensed and, more recently, to determine a derived vapour recovery volume, as per the patents noted above. The volume signal 34 is typically a series of volumetric pulses, each of which is representative of a predetermined volume of fuel delivered over the delivery path to the vehicle. Turning now to Figure 2, the preferred embodiment employs a fuel flow meter 24 which produces a fuel volume signal 34 by generating a digital transition for a given specific volume through the fuel flow meter 24. The output of the fuel flow meter 24 is fed to the control system 26. The control system 26 may count transitions in the fuel volume signal 34 over a fixed increment of time to yield a numerical value directly proportional to the flow rate of fuel through the fuel passageway 8. Preferably, the fixed time increment is 250 milliseconds (ms). Alternatively, the control system 26 measures the period of time between the transitions of the fuel volume signal 34 to yield a numerical value inversely proportional to a flow rate through the fuel passageway 8. With either method of determining flow rate, the control system 26 calculates flow rate throughout each fuelling operation. In operation, the control system 26 monitors fuel flow rate over a series of cycles. Each cycle generally includes a plurality of fuelling operations and is typically defined by a predetermined amount of fuel being delivered. Preferably, the first cycle is defined as being 10,000 US gallons, or 38,000 litres of product, while the second and any additional cycles are 5,000 US gallons, or 19,000 litres of product. The controller 26 stores the maximum flow rate recorded for each cycle and compares the maximum flow rates with subsequent cycles to determine when the maximum flow rate for the latter cycle drops from the first cycle by a predetermined amount from a first cycle thereby indicating an unclean filter. Maximum delivery rate drops between successive cycles may also be used to determine a filter is unclean. Preferably, a drop in the flow rate of two gallons, or seven litres per minute or more will be used to indicate the filter is sufficiently unclean to require changing. If the drop between the first and second cycles is not greater than the predetermined amount indicative of an unclean filter, the controller monitors flow rates and records a maximum flow rate during a third cycle. The maximum flow rates for the first and third cycles are compared and if the third cycle maximum flow rate has dropped by the predetermined amount from the first cycle maximum flow rate, indicating an unclean filter, the control system recognizes that the filter is unclean and needs changing. The control system 26 provides a filter status sensor signal 36 to an output device 40 once an unclean filter is detected. The output device 40 may be an audio and/or visual output device in the dispenser, at a central site controller or other remote location, among others. Whatever the embodiment, it is important that the filter status signal 36 alerts the service station operator or other service provider that the filter 20 needs to be changed. The flow chart of Figures 3A-3D outlines the operation of the preferred embodiment. The control system 26 begins (block 100) by initializing, and preferably resetting, values (block 102) stored in various memory locations which store values indicative of the maximum flow rate occurring during a respective cycle. The control system 26 initially awaits the beginning of a new fuelling operation (block 104). When a new fuelling operation begins, pulses are received from the flow meter 24 (block 106) and the control system 26 determines the current flow rate (block 108). As noted, the flow rate may be determined by counting the number of pulses, which represent a known volume of fuel, occurring within a defined unit of time, preferably 250 ms. Alternatively, the period of time between volume pulses can be used as a measure of the inverse of the flow rate, permitting computation of the flow rate. The control system 26 next compares the current flow rate with a first maximum flow rate value stored in a first memory location in the memory 30 (block 110). The control system 26 determines if the current flow rate is greater than the first maximum flow rate value stored in memory (block 112). If the current flow rate is greater than the maximum flow rate value, the stored maximum flow rate value is replaced with the current flow rate. Initially, the maximum flow rate values are reset to zero and the first measured current flow rate will usually be greater than the maximum flow rate value. If the current flow rate is not greater than the maximum flow rate value, the control system 26 determines if the first cycle has come to an end (block 116). The first cycle may be defined as a predefined number of gallons being delivered or a set amount of time. If it is not the end of the first cycle, the control system 26 determines if the fuelling operation is at an end (block 118). If the fuelling operation is not at an end, the control system 26 continues to receive pulses from the flow meter (block 106), determine the current flow rate (block 108), compare the current flow rate with the maximum flow rate value stored in memory (block 110) and replace the first maximum flow rate value if the current flow rate value is greater than the maximum flow rate value (blocks 112 and 114). If the end of fuelling operation has occurred, the control system awaits the begirining of a new fuelling operation (block 104), wherein the process is repeated until the end of the first cycle (block 116). Notably, whether or not a cycle ends during a fuelling operation is a matter of design choice. Assuming that the first cycle ends during a fuelling operation, the control system continues to receive pulses from the flow meter (block 120) and determine current flow rates (block 122). At this point, the control system is operating in a second cycle. Notably, the control system 26 compares the current flow rates with a second maximum flow rate value stored in a memory location in memory 30. The controller next determines if the current flow rate is greater than the second maximum flow rate value stored in memory (block 126). If the current flow rate is greater than the second maximum flow rate value, the second maximum flow rate value stored in memory is replaced with the current flow rate (block 128). If the current flow rate is less than the second maximum flow rate value, the control system does not replace the stored, maximum flow rate value. Subsequently, the control system 26 determines if the second cycle has come to an end (block 130). If the second cycle is not at an end, the control system 26 determines if the current fuelling operation is at an end (block 132). If the operation is not at an end, the control system repeats the process for the second cycle by receiving pulses (block 120), determining current flow rates (block 122), comparing current flow rates with the second maximum flow rate value (block 124) and updating the maximum flow rate value accordingly (blocks 126 and 128) until the second cycle ends. If fuelling operation is at an end, but the second cycle is not, the control system 26 awaits the beginning of a new fuelling operation (block 134) wherein the process of updating the maximum flow rate value is repeated until the end of the second cycle. At the end of the second cycle, the control system 26 compares the first and second maximum flow rate values (block 136) to determine if the second maximum flow rate value has decreased from the first maximum flow rate value by a predefined amount (block 138) indicative of a flow rate decrease associated with an unclean filter. If the maximum flow rate value for the second cycle is lower by the predefined amount, the control system 26 activates a filter status signal (block 140) to alert the appropriate machinery or personnel that the fuel filter needs replacing. Once the filter is replaced, the process returns to the beginning (block 100) wherein the maximum flow rate values for the first and second cycles are reset and the process begins anew. If the maximum flow rate value for the second cycle has not decreased from the maximum flow rate value of the first cycle by the predefined amount, a third cycle begins (block 144) wherein the control system 26 continues to receive pulses from the flow meter 24. The control system 26, as done in the earlier cycles, determines current flow rates (block 146) and compares the current flow rates with a third maximum flow rate value (block 148). The control system 26 determines if the current flow rate is greater than the third maximum flow rate value (block 150) and replaces the third flow rate value with the current flow rate (block 152) as necessary. If the current flow rate is not greater than the third maximum flow rate value, the maximum flow rate value is not stored and memory is not changed. The control system 26 next determines if the end of the third cycle has occurred (block 154). If it is not the end of the third cycle, the control system determines if it is the end of the current fuelling operation (block 156). If it is the end of the fuelling operation, the control system 26 awaits the beginning of a new fuelling operation (block 158). If it is not the end of the fuelling operation, the control system 26 continues to receive pulses from the meter (block 144), determine current flow rates 146, compare the current flow rates with the third maximum flow rate value (block 148) and update the latter as necessary (blocks 150 and 152). At the end of the third cycle (block 154), the control system 26 compares the first and third maximum flow rate values stored in memory (block 160) and determines if the third maximum flow rate value is less than the first maximum flow rate value by more than the predefined amount indicative of an unclean filter (block 162). If the third maximum flow rate value is less than the first maximum flow rate value by the predefined amount, the control system 26 activates the filter status signal 36 to indicate that the filter 20 needs to be replaced. At this point, the control system 26 reverts back to the beginning (blocks 100 and 166) and resets the maximum flow rate values stored in memory and the process begins anew. If the third maximum flow rate value is not less than the first maximum flow rate value by the predefined amount, the process repeats itself for a fourth cycle (block 168). The control system 26 during the fourth cycle will determine and compare current flow rates with a fourth maximum flow rate value until the cycle ends wherein a comparison is made to see if the latest maximum flow rate value stored in memory is less than the first maximum flow rate by the predefined amount. The process will repeat itself until filter replacement is required. Alternatively, the control system 26 may compare the maximum flow rate values during the cycles with a fixed minimum flow rate indicative of an unclean filter. Thus, instead of comparing maximum flow rates recorded during different cycles, the maximum flow rate for each cycle is compared with the minimum acceptable maximum flow rate value. Certain modifications and improvements will occur to those skilled in the art upon reading of the foregoing 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 in the scope of the following claims. For example, other flow rate maxima for the various cycles can be used, such as maximum averages or the like. Also, the notion of fixed "cycles" need not be used - the system may use any concept of later fuellings being capable of generating only slower fuellings than earlier fuellings. It is useful to consider a maximum rate during earlier and later periods (or cycles) to avoid any particular slow later fuelling caused by, for example, a customer who chooses to fuel slowly, from giving a false reading of a clogged filter.

Claims: CLAIMS 1. A fuel dispenser having a filter status sensor comprising: a fuel delivery path: a fuel filter in the fuel delivery path: a flow monitor in the delivery path for measuring fuel flow in the delivery path; and a controller associated with the flow monitor adapted to determine and compare a first flow rate determined during a first cycle with a second flow rate determined during a second cycle and provide a filter status signal when the first and second flow rates differ by more than a predetermined amount. 2. The fuel dispenser of claim 1 , wherein the first flow rate is a maximum flow rate occurring during the first cycle and the second flow rate is a maximum flow rate occurring during the second cycle. 3. The fuel dispenser of claim 1 or 2, wherein, when the first and second flow rates do not differ by more than the predetermined amount after the first and second cycles, the controller is further adapted to compare the first flow rate with a third flow rate determined during a third cycle and provide a filter status signal when the first and third flow rates differ by more than a predetermined amount. 4. The fuel dispenser of claim 3, wherein the third flow rate is a maximum flow rate occurring during the third cycle. 5. The fuel dispenser of claims 2, 3 or 4, wherein the controller is associated with a plurality of memory locations and is adapted to store the flow rates during each cycle in respective ones of the memory locations and update the flow rates when a new maximum flow rate occurs during each cycle. 6. The fuel dispenser of claim 5, wherein one memory location serves as the second memory location during the second cycle and as the third memory location during the third cycle. 7. The fuel dispenser of any preceding claim, wherein each cycle includes a plurality of fuelling operations. 8. The fuel dispenser of any preceding claim, wherein each cycle is defined by a predetermined quantity of fuel to be delivered. 9. The fuel dispenser of claim 8, wherein the predetermined quantity of fuel for the first cycle is over 19,000 litres. 10. The fuel dispenser of claim 8 or 9, wherein the predetermined quantity of fuel for the second cycle is less than for the first cycle. 1 1. The fuel dispenser of any preceding claim, wherein each cycle is defined by a predetermined amount of operating time. 12. The sensor of any preceding claim, wherein the predetermined amount of difference between flow rates is seven litres per minute. 13. The fuel dispenser of any preceding claim, wherein each cycle is defined by a predetermined number of transactions. 14. A method for providing a filter status signal associated with a fuel dispenser having a fuel delivery path, a filter along the delivery path and a flow monitor providing a flow signal representative of a quantity of fuel flow, the method comprising: generating a flow signal representative of a quantity of fuel flow during a plurality of fuelling operations; determining current flow rates based on the quantity of fuel flow per unit of time; comparing the current flow rate with a first maximum flow rate value stored in a first memory location during a first cycle; storing the current flow rate in the first memory location if the current flow rate is greater than the first maximum flow rate value stored in the first memory location during the first cycle; comparing the current flow rate with a second maximum flow rate value stored in a second memory location during a second cycle; storing the current flow rate in the second memory location if the current flow rate is greater than the second maximum flow rate value stored in the second memory location during the second cycle; comparing the first maximum flow rate value and the second maximum flow rate value after the first and second cycles; and providing a filter status signal when the first and second maximum flow rate values differ by more than a predetermined amount. 15. The method of claim 14. wherein, when the maximum flow rate values for the first and second cycles do not differ by more than the predetermined difference, the method further comprises the steps of: comparing the current flow rate with a third maximum flow rate value stored in a third memory location during a third cycle; storing the current flow rate in the third memory location if the current flow rate is greater than the third maximum flow rate value stored in the third memory location during the third cycle; comparing the first maximum flow rate value and the third maximum flow rate value after the third cycle; and providing a filter status signal if the first and third maximum flow rate values differ by more than the predetermined amount.

Inventors: MCSPADDEN JOHN S, MCSPADDEN, JOHN, S.
Applicants: GILBARCO LTD, GILBARCO LIMITED
Application year: 1998
Main classification: B67D5
IPC codes: B67D5