Precision fuel dispenser

A fuel dispenser for delivering fuel along a fuel delivery path, a flow rate modulator in the fuel delivery path and a control system operatively associated with the flow rate modulator for regulating the rate of flow in the fuel delivery path during a fueling operation to achieve a flow-rate-dependent result. The precision fuel dispenser may further include a flow transducer in the fuel delivery path configured to provide a flow transducer signal representing a volume of fuel flow in the fuel delivery path to the control system.

BACKGROUND OF THE INVENTION 
The present invention relates generally to fuel dispensers and, more 
particularly, to fuel dispensers for precisely delivering and controlling 
the rate of fuel flow to a vehicle or container during a fueling 
operation. 
Federal regulations will limit vehicle fueling to ten gallons per minute 
(GPM) beginning in 1996 in order to achieve legislated limits on the 
amount of spillage from vehicle fueling operations. See 58 Federal 
Register 16019. Gasoline dispensers will be restricted to a maximum 
delivery rate of 10 GPM in an effort to reduce fuel spit-back and spillage 
and the resultant exposure of fuel to customers and the environment. The 
current technology for restricting fuel delivery rate on gasoline 
dispensers is to install restrictive orifices at accessible points in the 
delivery system and/or vary hose and nozzle configurations, otherwise 
known as hanging hardware, accordingly. 
The accuracy of restricted orifices and hanging hardware inherently suffers 
from fluctuations in system feed pressure. System feed pressure is 
affected by a number of variables including the number of active fueling 
positions, clogged fuel filters, kinked hoses and other deteriorating 
components along a fuel delivery path. The requisite restriction is 
dependent upon site specifics, such as, but not limited to, pumping device 
capacity, pipe diameter, pipe length, head height, hose diameter, hose 
length and nozzle type. These factors prevent effective factory presetting 
of desired fuel delivery rates. Moreover, orifices and hardware are 
subject to tampering, removal or substitution in an effort to defeat flow 
restrictions. When fuel pumps incorporating the current technology are 
checked for compliance with the regulations, the testing authority will 
check the highest flow delivery hose, typically the hose closest to the 
main turbine pump, with all other hoses inactive. Once adjustments are 
made to limit the high-flow hose to 10 GPM, the lower flow hoses will 
inherently deliver less than 10 GPM. The situation is exacerbated when 
multiple pumps are active. Under these situations, even the highest flow 
hose will often deliver significantly less than 10 GPM. 
Restrictive orifices and hanging hardware provide virtually no control over 
the fueling operation. Such hardware restricts flow rate at certain 
pressure levels. In other words, a 10 GPM restrictive orifice will allow 
fuel delivery at 10 GPM only under specific conditions. The fuel dispenser 
will deliver fuel at substantially less than 10 GPM a vast majority of the 
time, if not all of the time. Thus, with the current technology, the 
maximum delivery rate of 10 GPM will hardly ever be obtained, since a true 
optimization or average delivery rate cannot be controlled or calculated 
with presently existing fuel dispensers. 
The current technology does not provide a way to optimize fuel delivery 
while abiding by the government regulations. Current fuel dispensers 
cannot maximize delivery rates and minimize spillage while maintaining an 
average fuel delivery rate of 10 GPM during a substantial portion of the 
fueling operation. Individual fuel dispensers are unable to optimize and 
control fueling in multi-dispenser systems. Additionally, the current 
technology cannot provide precise regulation of fuel delivery under 
varying dynamic changes affecting the fuel delivery rate by site, 
dispenser, user and other variables. For example, substantial changes in 
pressure within the fuel delivery system occur when other pumps within the 
system turn on or off, or adjust fueling rates. Currently, these changes 
in pressure prevent precise fueling regulation and optimization. 
Furthermore, current fuel dispensers are unable to adequately control 
delivery rate overshoot and undershoot or provide sufficient system 
response times. Without such control, precisely controlling a fueling 
operation is virtually impossible. 
With the inability to precisely control and optimize the fueling operation, 
current dispensers are unable to precisely control the ramping up of the 
delivery rate to prevent the initial surge at the onset of fueling or the 
ramping down of the flow rate to quickly and efficiently reach pre-set 
sale values. Providing a fuel dispenser capable of precisely controlling 
the entire fueling operation would enable a very smooth, quick and 
efficient fueling operation. The applicant's invention provides this 
capability, which was previously unavailable. 
A precisely controlled fueling operation provides greater environmental 
protection capability by minimizing fuel spillage and spit-back. By 
reducing the initial surge at the onset of fueling and ramping down the 
flow rate towards the end of fueling, the amount of fuel spilled is 
greatly reduced. Furthermore, precisely controlling the fuel delivery 
allows precise flow rate control dependent upon a number of predetermined 
cut-offs during a predetermined period of time. Rapid, successive cut-offs 
indicate splash-back or excessive turbulence in the nozzle's fill neck, a 
condition likely to lead to fuel spills. Fuel dispensers are currently 
unable to control the fueling operation to effectively react to scenarios 
leading to fuel spills. The applicant's invention provides such control to 
both minimize fuel spills and optimize fueling. 
A further disadvantage of current fuel dispensers is the inability to 
automatically compensate for deteriorating components which nominally 
reduce flow. Components which often reduce flow include clogged fuel 
filters and kinked hoses. The applicant's invention allows fueling 
optimization even when the system components are not optimum. For example, 
as the fuel filter fills with debris, the flow control signal to the 
system fuel pump is increased in an amount to precisely compensate for any 
flow rate loss. 
A further shortcoming of the current fuel dispenser technology is the 
inability for the system to signal when certain flow rates are no longer 
achievable. Such indications would alert the user or owner of a filter 
needing replacement, a hose deformation or some other condition 
obstructing the fuel passageway. The applicant's invention provides the 
ability to precisely monitor flow rate and provide a signal indicating 
when certain flow rates are unachievable due to various system conditions. 
Thus, there remains a need for a new and improved fuel dispenser capable of 
optimizing fuel flow rate per regulatory agency mandate while maximizing 
site throughput under varying dynamic conditions. A need exists for a fuel 
dispenser capable of delivering fuel at precise flow rates independent of 
site variations and capable of being manufactured in a manner requiring no 
field modifications or calibrations. A further need exists for providing 
precise fuel delivery in a cost effective manner and providing for 
efficient modification of existing fuel dispensers. Furthermore, there 
remains a need for a fuel dispenser capable of delivering fuel to achieve 
a flow-rate-dependent result to optimize fueling while minimizing 
spillage. Additionally, there remains a need for a fuel dispenser capable 
of compensating for deteriorating components and providing information 
indicative of the fuel delivery path condition. 
SUMMARY OF THE INVENTION 
The present invention is directed to a precision fuel dispenser capable of 
precisely controlling the rate of fuel flow to a vehicle or container 
during a fueling operation. 
Accordingly, one aspect of the present invention is to provide a fuel 
dispenser for delivering fuel along a fuel delivery path, a flow rate 
modulator in the fuel delivery path and a control system operatively 
associated with the flow rate modulator for regulating the rate of flow in 
the fuel delivery path during a fueling operation to achieve a 
flow-rate-dependent result. The precision fuel dispenser may further 
include a flow transducer in the fuel delivery path configured to provide 
a flow transducer signal representing a volume of fuel flow in the fuel 
delivery path to the control system. 
The flow transducer signal may provide data to allow calculation of flow 
rate or may provide flow rate information directly. Furthermore, 
ascertaining the flow rate is important. The way the flow rate is 
determined will vary according to the specific application. Currently, 
pulsers are used to provide a volume signal from which flow rate is easily 
calculated. However, any way to measure flow rate is acceptable with or 
without actual volume measurements. 
The dispenser's control system may derive a forcing function from 
differences between an actual flow rate determined from the flow 
transducer signal and a desired flow rate, the control system further 
regulates the rate of flow in the fuel delivery path according to the 
forcing function. 
Another aspect of the present invention is to provide a precision fuel 
dispenser wherein the control system has a reference flow rate 
representing a desired flow rate. The control system regulates the rate of 
flow in the fuel delivery path to achieve the reference flow rate. 
Another aspect of the present invention is to provide a precision fuel 
dispenser capable of optimizing the fueling operation to maximize fueling 
rates while minimizing fuel spillage. The dispenser control system may 
ramp up the rate of flow in the delivery path from a lower rate of flow to 
minimize initial fuel surge, which often leads to fuel spillage. The 
control system may ramp down the rate of flow in the delivery path from a 
higher rate of flow to reduce the chance of fuel spillage at the end of 
fueling. 
Controlling the ramping up or down of the fueling rate also aids in fueling 
optimization and precise delivery control with little or no over- or 
undershoot of desired flow rates. The control system may control the rate 
of flow in the delivery path to provide a predetermined average rate of 
flow during a portion of the fueling operation. Such control allows 
fueling optimization and reduces fuel spillage. 
In particular, regulatory mandates may be periodically exceeded while 
maintaining the regulated average. This provides a significant advantage 
with multiple dispenser systems which often fuel well under acceptable 
flow rates due to pressure losses associated with operating multiple 
pumps. Similarly, the control system may control the rate of flow in the 
delivery path to provide a predetermined average rate of flow during most 
of the fueling operation. The control system may control the rate of flow 
in the delivery path to provide a predetermined rate of flow under varying 
dynamic conditions. These conditions may include pressure changes and 
component failures or deterioration. Even under such diverse conditions, 
the invention can optimize fueling. Similarly, the control system may 
control the rate of flow in the delivery path to provide a predetermined 
average rate of flow under varying dynamic conditions. A related aspect of 
the control systems is to control the rate of flow in the delivery path to 
compensate for deteriorating components or obstructions which reduce flow. 
The control system reduces fuel spillage and protects the environment by 
controlling the rate of flow in the delivery path to provide a reduced 
rate of flow after a premature automatic shut-off. Premature shut-offs 
indicate excessive turbulence in the fill neck which increases the risk of 
spilling fuel. Further protection from spillage is provided by controlling 
the rate of flow in the delivery path to assist in topping off a fueling 
operation, controlling the rate of flow in the delivery path to provide a 
reduced rate of flow when a predetermined number of automatic shut-offs 
occur, or controlling the rate of flow in the delivery path to provide a 
reduced rate of flow when a predetermined number of automatic shut-offs 
occur within a predetermined period of time. 
Another aspect of the present invention is configuring the control system 
to indicate when a certain rate of flow is not achievable, when fuel flow 
is inhibited, when a filter needs replaced, when a delivery hose is 
deformed, or when the delivery path is otherwise obstructed. Providing 
such indications enables delivery and system diagnostics unobtainable in 
prior dispensers. 
Another aspect of the present invention is to provide a precision fuel 
dispenser wherein the flow rate modulator includes a control valve. 
Another aspect of the present invention is to provide a precision fuel 
dispenser wherein the flow rate transducer includes a flow meter and the 
transducer signals include volumetric pulses to the control system. 
Another aspect of the present invention is to provide a method of 
delivering fuel including the steps of delivering fuel along a fuel 
delivery path, modulating fuel flow in the fuel delivery path, and 
controlling the modulating of fuel flow to regulate the rate of flow in 
the fuel delivery path during a fueling operation to achieve a 
flow-rate-dependent result. The method of delivering fuel may also include 
providing a flow signal representing a volume of fuel flow in the fuel 
delivery path. The method of delivering fuel may further include deriving 
a forcing function from differences between an actual flow rate determined 
from the flow signal and a desired flow rate, and regulating the rate of 
flow in the fuel delivery path according to the forcing function. 
Another aspect of the present invention is to provide a method of 
delivering fuel including the step of providing a reference flow rate 
representing a desired flow rate and regulating the rate of flow in the 
fuel delivery path to achieve the reference flow rate. 
Still another aspect of the present invention is to provide a method of 
delivering fuel capable of ramping up the rate of flow in the delivery 
path from a lower rate of flow to achieve a flow-rate-dependent result. 
Another aspect of the present invention is to provide a method of 
delivering fuel capable of ramping down the rate of flow in the delivery 
path from a higher rate of flow to achieve a flow-rate-dependent result. 
Another aspect of the present invention is to provide a method of 
delivering fuel capable of controlling the rate of flow in the delivery 
path to provide a predetermined average rate of flow during a portion of 
the fueling operation to achieve a flow-rate-dependent result. 
Another aspect of the present invention is to provide a method of 
delivering fuel capable of controlling the rate of flow in the delivery 
path to provide a predetermined average rate of flow during most of the 
fueling operation to achieve a flow-rate-dependent result. 
Another aspect of the present invention is to provide a method of 
delivering fuel capable of controlling the rate of flow in the delivery 
path to provide a predetermined rate of flow under varying dynamic 
conditions to achieve a flow-rate-dependent result. 
Another aspect of the present invention is to provide a method of 
delivering fuel capable of controlling the rate of flow in the delivery 
path to provide a predetermined average rate of flow under varying dynamic 
conditions to achieve a flow-rate-dependent result. 
Another aspect of the present invention is to provide a method of 
delivering fuel capable of controlling the rate of flow in the delivery 
path to provide a reduced rate of flow after a premature automatic 
shut-off. 
Another aspect of the present invention is to provide a method of 
delivering fuel capable of controlling the rate of flow in the delivery 
path to assist in topping off a fueling operation. 
Another aspect of the present invention is to provide a method of 
delivering fuel capable of controlling the rate of flow in the delivery 
path to provide a reduced rate of flow when a predetermined number of 
automatic shut-offs occur. 
Another aspect of the present invention is to provide a method of 
delivering fuel-capable of controlling the rate of flow in the delivery 
path to provide a reduced rate of flow when a predetermined number of 
automatic shut-offs occur within a predetermined period of time. 
Another aspect of the present invention is to provide a method of 
delivering fuel capable of controlling the rate of flow in the delivery 
path to compensate for deteriorating components which reduce flow. 
Another aspect of the present invention is to provide a method of 
delivering fuel capable of indicating when a certain rate of flow is not 
achievable, when fuel flow is inhibited, when a filter needs replaced, 
when a delivery hose is deformed or when the delivery path is otherwise 
obstructed. 
Yet another aspect of the present invention is to provide a method of 
controlling fuel flow along a fuel path including the steps of providing a 
desired flow rate for regulating the rate of flow in the fuel delivery 
path during a fueling operation, providing an actual flow rate, deriving a 
forcing function according to a difference between the desired and actual 
flow rate, modulating the flow of fuel in the fuel path according to the 
forcing function, and regulating the rate of flow in the fuel delivery 
path during a fueling operation to achieve a flow-rate-dependent result.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to the drawings in general and FIG. 1 in particular, it will 
be understood that the illustrations are for the purpose of describing a 
preferred embodiment of the invention and are not intended to limit the 
invention thereto. As best seen in FIG. 1, in a typical service station, 
an automobile 100 is shown being fueled from a gasoline dispenser 10. A 
spout 2 of nozzle 4 is shown inserted into a filler pipe 102 of a fuel 
tank 104 during the refueling of the automobile 100. 
A fuel delivery hose 6 having vapor recovery capability is connected at one 
end to the nozzle 4, and at its other end to the fuel dispenser 10. 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 gasoline pumped from an underground storage tank 12 to the 
nozzle 2. Gasoline 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 vapor recovery passageway 14 for transferring fuel vapors expelled 
from the vehicle's fuel tank 104 to the underground storage tank 12 during 
the refueling of the vehicle 100. 
A vapor recovery pump 28 provides a vacuum in the vapor recovery passageway 
14 for removing fuel vapor during a refueling operation. The vapor 
recovery system using the pump 28 may be any suitable system such as those 
shown in U.S. Pat. Nos. 5,040,577 to Pope, 5,195,564 to Spalding, 
5,333,655 to Bergamini et al., or 3,016,928 to Brandt. In addition, the 
invention is useful on dispensers that are not vapor recovery dispensers. 
The fuel delivery passageway 8 typically 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. 
In the preferred embodiment, the control valve 22 acts as a flow modulator, 
and the flow meter 24 acts as a fuel flow transducer. 
Turning now to FIG. 2, the preferred embodiment employs one fuel flow 
transducer 24 which produces a fuel volume signal 34 by generating a 
digital transition for a given specific volume through the fuel flow 
transducer 24. The output of the fuel flow transducer 24 is fed to the 
control system 26. The control system 26 measures the period 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. 
Alternatively, the control system 26 may count transitions in the fuel 
volume signal 34 over a fixed period of time to yield a numerical value 
directly proportional to the flow rate of fuel through the fuel passageway 
8. With either method, the flow rate is compared with a desired reference 
value by the control system 26 to obtain system error. The reference 
signal may be stored or calculated by the control system 26 or read from a 
delivery rate reference source 30 via a delivery rate reference signal 36. 
The reference value may be a numerical coefficient or derived from an 
external source such as an oscillator whose input is processed in similar 
fashion to the flow measurement device. The reference may represent the 
maximum allowable delivery rate, a value representative of the desired 
system delivery rate or a value representing a flow-rate-dependent result. 
The result of the comparison of the flow rate value and reference value 
represents an error value which is a scalar of the difference between the 
desired and actual fuel delivery rate. The error value is inputted into a 
conventional proportional-integral-derivative (PID) algorithm by the 
control system 26 to derive a forcing function 32 which is outputted to a 
flow rate modulator 22. The flow rate modulator 22 may include an 
electromechanically driven valve or any controllable flow restricting 
device. The flow rate modulator 22 is preferably actuated in proper phase 
with a servo loop. 
Turning now to FIG. 3, the forcing function may modulate the pumping rate 
of variable speed fuel pump 29. 
Those of ordinary skill in the art are able to program control system 26 
with a suitable PID algorithm. The preferred embodiments use a PID 
feedback control system with greater than unity gain. The PID feedback 
control system is easily implemented and the PID coefficients are chosen 
to compensate for any mechanical or electrical time constants and delays 
present in the fuel delivery system of the fuel dispenser 10, thereby 
effecting improved regulative response to dynamic changes imposed by site, 
dispenser, user or other variables which would otherwise affect 
unregulated fuel delivery rates. 
The feedback control system may be modified and the regulatory functions 
still effectively implemented by deleting the derivative term at the 
compromise of delivery rate overshoot, undershoot or system response time. 
Alternatively, a unity or less than unity gain feedback control system may 
be implemented by modulating the flow rate modulator 22 or variable speed 
pump 29 at a rate equal to or less than the sum of mechanical and 
electrical system delays at greater compromise of delivery rate overshoot, 
undershoot or system response time. Those of ordinary skill in the art 
will recognize that other feedback systems of lesser or greater complexity 
and of lesser or greater performance may be implemented to achieve fuel 
delivery rate regulations. However, the preferred embodiment will include 
a reference signal or value representative of the desired delivery rate, a 
feedback signal or value comprising or representing the actual delivery 
rate, the digital, analog, mechanical or mixed embodiment processor which 
inputs the reference and feedback signals to derive a forcing function and 
a controlling device receiving the forcing function capable of modulating 
the fuel delivery rate. Systems requiring a lesser degree of accuracy or 
having a very precise and controllable flow rate modulator may not require 
feedback. 
Applicant's invention provides a cost effective method to achieve product 
flow control in a gasoline dispenser by utilizing existing electronics and 
hydraulic components, by modifying the control software. Current gasoline 
dispensers have a controller 26 for controlling all functions of the 
dispenser, a positive displacement flow meter 24, and one or more control 
valves 22 for turning on or off the product flow. The controller can be 
modified to monitor the signals 34 from the flow meter 24, calculate an 
actual flow rate from signals 34 and send modulating signals 32 to control 
valve 22 to control the flow rate to desired levels, such as 10 GPM. 
In operation, the control system 26 (for either FIG. 2 or FIG. 3) may 
affect a variety of flow rate control functions to achieve a 
flow-rate-dependent result. The control system may be configured to 
control the flow rate according to a reference flow rate. As discussed 
above, the reference may come from within the control system 26 or be 
received from the reference 30. FIG. 4 depicts a basic control outline for 
a typical fueling operation. Block 40 indicates the beginning of a fueling 
operation. During the fueling operation, the controller determines whether 
the actual flow rate is equal to the reference or desired flow rate at 
decision block 42. If the rates are not equal, the flow rate is adjusted 
toward the reference or desired flow rate at block 44. Once the flow rate 
is adjusted at block 44, the controller returns to decision 42 to 
determine whether the actual and reference flow rates are equal. The flow 
rate is continually adjusted until the actual and reference flow rates are 
equal. Once the reference flow rate is achieved, the controller will 
deliver fuel at a constant flow rate at block 46. The controller 26 will 
check to see if the fueling operation is at an end at decision block 48. 
If the fueling operation is at an end, the controller 26 will stop fueling 
at block 50. If the fueling operation is not at an end, the controller 26 
returns to decision block 42 to determine if the actual and reference or 
desired flow rates are equal. The process is repeated until fueling is 
stopped. 
FIG. 5 is a flow chart setting out the basic control process for ramping 
down the fueling rate during a fueling operation. The fueling operation 
begins at block 52. The controller 26 determines whether to ramp down the 
fueling rate at decision block 54. The fueling rate is decreased 
accordingly at block 56, if necessary. Once the fueling rate is decreased, 
the control system 26 returns to decision block 54. When the fueling rate 
does not require ramping down, the control system 26 causes fuel to be 
delivered at a constant rate at block 58. The control system 26 next 
checks for an end to the fueling operation at decision block 60. If the 
fueling operation is at an end, the controller 26 stops fueling at block 
62. If the fueling operation is not at an end, the control system 26 
returns to decision block 54 and reiterates the process. Those of ordinary 
skill in the art will understand that the terms ramp or ramping will 
include not only constant and variable flow rate changes, but also abrupt 
step changes in flow rates. Ramping down the flow rate may be used to slow 
the rate of fueling for pre-set sales, assist the customer in smoothly 
ending the fueling operation, or adjust the flow rate to a lower desired 
or reference flow rate in order to optimize fueling and minimize spillage. 
Likewise, the system may ramp up the flow rate from a reduced value to 
mitigate the initial surge at the onset of fueling to reduce fuel spillage 
or to increase the fueling rate to a desired or reference level. FIG. 6 
depicts a flow chart for ramping up the flow rate. The fueling operation 
begins at block 64. During the fueling operation, the control system 26 
determines whether it is necessary to ramp up the fueling rate at decision 
block 66. If the fueling rate needs increased, the control system 26 
increases the fueling rate at block 68 and returns to decision block 66 to 
determine if a further increase is necessary. When the fueling rate does 
not require an increase, the control system 26 causes the delivery of fuel 
at a constant rate at block 70. The control system 26 determines whether 
the fueling operation is at an end at decision block 72. If the fueling 
operation is at an end, fueling is stopped at block 74. If the fueling 
operation is not at an end, the control system 26 returns to decision 
block 66 to reiterate the process. 
FIG. 7 provides a flow chart outlining a basic control process for 
providing a desired average flow rate during a portion of the fueling 
operation. The fueling operation begins at block 76. The control system 
determines whether or not to provide a desired average flow rate at 
decision block 78. If a desired average flow rate is required, the flow 
rate is adjusted in a manner calculated to reach the desired average flow 
rate at block 80. Providing an average flow rate allows the controller to 
deliver fuel at an average flow rate throughout a large portion of the 
fueling operation. For example, if the average fueling rate has to be 10 
GPM or less during the fueling operation, the dispenser may deliver fuel 
significantly above 10 GPM to compensate for the lower delivery rates 
during the beginning and/or end of the fueling operation. This feature 
achieves two major goals: first, a station operator improves customer 
throughput and second, customers receive fuel in a faster and safer 
manner. Such control is currently unavailable in the industry. 
Once the average flow rate is achieved, the control system causes fueling 
at a constant rate at block 82. The control system determines whether the 
fueling operation is at an end at decision block 84. If the fueling 
operation is at an end, fueling is stopped at block 86. If the fueling 
operation is not at an end, the control system 26 returns to decision 
block 78 to further check and/or adjust the fueling rate to provide the 
desired average flow rate. The control system 26 may also control the rate 
of flow in the delivery path to provide a predetermined average rate of 
flow during various portions of the fueling operation. 
FIG. 8 is a flow chart depicting a control process similar to that of FIG. 
7. FIG. 8 provides a control process capable of compensating for dynamic 
changes in the fueling operation. The cause of these dynamic changes are 
often due to pressure changes in the fuel delivery system when multiple 
dispensers are turned on or off during the fueling operation, or a 
customer manually or accidentally adjusts the fueling rate or causes a 
premature cut-off. Current technology does not allow the dispenser to 
recover and continue to deliver fuel at a high average delivery rate. 
Current systems are restricted to delivering fuel at the maximum flow rate 
allowed by the mechanical flow restrictors. In most cases, reduced system 
feed pressure prevents fueling at rates equal to the mechanical flow 
restrictors' maximum allowable flow rate. 
The current invention overcomes the inherent limitations of the mechanical 
restrictors by allowing fuel delivery rates to instantaneously and 
periodically rise above the average flow rates set by governmental 
regulations to provide an average flow rate meeting these regulations. 
The fueling operation begins at block 88. The control system 26 determines 
whether there is a need to compensate for a dynamic change occurring 
during the fueling operation at decision block 90. If such a change is 
necessary, the control system 26 adjusts the flow rate to compensate for 
the condition at block 92 and returns to decision block 90 in an iterative 
manner. If the control system does not need to compensate for a dynamic 
condition, the fueling rate is held constant at block 94. The control 
system 26 determines whether the fueling operation is at an end at 
decision block 96. If the fueling operation is at an end, the control 
system 26 stops fueling at block 100. If the fueling operation is not at 
an end, the control system 26 returns to decision block 90 to determine 
whether the fueling rate requires further compensation. 
FIG. 9 depicts a flow chart outlining a control process for compensating 
delivery rates for deteriorating components which nominally reduce flow, 
such as fuel filters and kinked hoses, or other obstructions within the 
fuel passageway 8. Currently available fuel dispenser systems are unable 
to utilize excess site delivery capacity to automatically compensate for 
conditions negatively affecting flow. 
Typically, additional restrictions simply further reduce flow rates 
substantially below allowed delivery rates. The current invention 
overcomes the limitations of the prior art by eliminating the need for 
mechanically restrictive orifices and utilizing a control valve 22. Many 
dispensers already include such a valve. When deteriorating components or 
passageway obstructions reduce flow rates, the current invention can use 
excess delivery capacity in conjunction with the control valve 22 in an 
effort to compensate for additional restrictions. 
The fueling operation begins at block 102. The control system 26 determines 
whether or not to compensate for component deterioration or other 
obstructions unduly limiting delivery rates at decision block 104. If 
compensation is required, the control system adjusts the flow rate in an 
effort to compensate for the reduced flow at block 106 and returns to 
decision block 104 in an iterative manner. Once compensation is complete, 
the control system 26 causes fueling at a constant rate at block 108. The 
control system 26 next determines whether the fueling operation is at an 
end at decision block 110. If the fueling operation is at an end, fueling 
is stopped at block 112. If the fueling operation is not at an end, the 
control system 26 returns to decision block 104 in an iterative manner. 
Equally important as optimizing the delivery of fuel during a fueling 
operation is minimizing the amount of fuel spilled during the operation. 
The enhanced control over the fueling operation provided by the current 
invention minimizes the amount of fuel spilled by controlling flow rates 
in a manner reducing the possibility of fuel spills. FIG. 10 is a flow 
chart depicting a control process for assisting a user in topping off a 
fueling operation in a manner minimizing the potential for spilling fuel. 
The fueling operation begins at block 114. Nearing the end of the fueling 
operation, the control system 26 determines whether or not the user is at 
or near a topping off point in the fueling operation. The system may 
recognize that the topping off point is near at decision block 116 when 
automatic shutoffs begin to occur, a pre-set sale or amount is being 
reached, or the fuel dispenser has received information from the operator 
or vehicle regarding the amount of fuel necessary to fill the tank. If a 
topping off point in the fueling operation occurs, the control system 26 
reduces the flow rate in a manner assisting topping off and minimizing the 
potential for spilling fuel at decision block 118 and returns to decision 
block 116. If the system is not near the topping off point, the control 
system 26 continues fueling at block 120. The control system 26 
subsequently determines whether the fueling operation is at an end at 
block 122. If the fueling operation is at an end, fueling is stopped at 
block 124. If the fueling operation is not at an end, the control system 
26 returns to decision block 116 in an iterative manner. The topping off 
control process of FIG. 10 may also provide further fueling optimization. 
By reducing the flow rate to zero in a controlled fashion, the slow, spill 
prone, manual topping off method currently used will be replaced by a 
quicker and safer fueling operation. 
FIGS. 11-13 depict a control process for reducing flow rates when one or 
more premature nozzle shutoffs occur in sequence or during a predetermined 
period of time. In FIG. 11, the fueling operation begins at block 126. The 
control system 26 determines whether a premature nozzle shutoff has 
occurred at decision block 128. If a shutoff has occurred, the flow rate 
is reduced in a manner minimizing the potential for spilling fuel, yet 
attempting to optimize the fueling operation at block 130. The control 
system 26 returns to decision block 128 in an iterative manner. If there 
is no premature nozzle shutoff, the fueling operation is continued at 
block 132 until the fueling operation reaches an end. The control system 
26 determines whether the fueling operation reaches an end at decision 
block 134. If the fueling operation is at an end, fueling is stopped at 
block 136. If the fueling operation is not at an end, the control system 
26 returns to decision block 128 in an iterative manner. 
In FIG. 12, the fueling operation begins at block 138. The control system 
26 determines whether a certain number of premature nozzle shutoffs have 
occurred at decision block 140. If such a number has occurred, the flow 
rate is reduced accordingly at block 142 and the control system 26 returns 
to decision block 140 in an iterative manner. If the certain number of 
premature nozzle shutoffs have not occurred, fueling is continued at block 
144 and the control system looks for an end to the fueling operation at 
decision block 146. If the fueling operation is at an end, fueling is 
stopped at block 148. If the fueling operation is not at an end, the 
control system 26 returns to decision block 140 in an iterative manner. 
A further refinement of the control process of FIG. 12 is that of FIG. 13. 
The fueling operation begins at block 150. The control system 26 
determines whether a certain number of nozzle shutoffs occur within a 
predetermined period of time at decision block 152. If such condition 
occurs, the flow rate is reduced accordingly to minimize fuel spillage 
while optimizing the fueling operation at block 154. Once the flow rate is 
reduced, the control system 26 returns to decision block 152 in an 
iterative manner. If the nozzle shutoff condition is not satisfied, the 
control system 26 continues fueling at block 156 and looks for an end to 
the fueling operation at decision block 158. If the fueling operation is 
at an end, fueling is stopped at block 160. If the fueling condition is 
not at an end, the control system 26 returns to decision block 152 in an 
iterative manner. 
Another advantage of the current invention is the ability to provide 
various warnings or indications of problems associated with the delivery 
path. Among other indications, the current system may be configured to 
indicate when a certain flow rate is not achieved or unachievable, the 
fuel filter is clogged or needs replaced, a delivery hose is deformed, or 
the delivery path is otherwise obstructed. FIG. 14 depicts a basic control 
process allowing the control system 26 to indicate when one or more of the 
above-mentioned problems arise during a fueling operation. The fueling 
operation begins at block 162. The control system 26 determines whether or 
not the desired flow rate is achievable at decision block 164. If the 
desired flow rate is unachievable, the control system 26 indicates that 
the flow rate is not achieved at block 166. The control system next 
attempts to determine whether the filter is causing the reduced flow rates 
at decision block 170. If the filter is the problem, the control system 26 
indicates that the filter needs attention at block 172. The control system 
26 next determines whether or not the reduced flow rates are caused by a 
deformed or kinked delivery hose at decision block 174. The control system 
26 will also progress to decision block 174 if the fuel filter is not 
causing reduced flow. 
If a hose is deformed, the control system 26 indicates this at block 176 
and proceeds to determine whether or not the delivery path is otherwise 
obstructed at decision block 178. The control system 26 also progresses to 
decision block 178 after a determination that the delivery hose is not 
causing the reduced flow. If the delivery path is otherwise obstructed, 
the control system 26 will indicate so at block 180 and continue fueling 
at block 168. If the delivery path is not otherwise obstructed, the 
control system 26 will continue fueling at block 168. 
If the desired flow rate is achievable, as determined at decision block 
164, the control system 26 will continue fueling at block 168. At this 
point, the control system 26 determines whether the fueling operation is 
at an end at decision block 182. If the fueling operation is at an end, 
fueling is stopped at block 184. If the fueling operation is not at an 
end, the control system 26 returns to decision block 164 in an iterative 
manner, further checking delivery rates. 
Those of ordinary skill in the art will realize that the various functions 
and embodiments discussed in conjunction with FIGS. 4-11 may be modified 
and combined in numerous ways, all of which are deemed within the scope of 
the applicant's invention. The aspects were discussed individually in the 
corresponding figures to better describe the respective embodiments. 
Certain modifications and improvements will occur to those skilled in the 
art upon a 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 within the scope 
of the following claims.