Abstrict A flow switch used on conjunction with a fuel flow meter in a fuel
dispenser to determine when fuel flow rate signals form a fuel flow
meter should be ignored in the calculation of flow rate and/or volume
of fuel dispensed. An inferential fuel flow meter may be used as
the fuel flow meter. The inferential fuel flow meter may be a turbine
flow meter that comprises one or more turbine rotors that rotate
in response to fuel flow flowing through the turbine flow meter.
The turbine rotors may continue to generate pulses even when fuel
is no longer flowing. A flow switch determines when fuel is actually
flowing and fuel is not actually flowing. The flow switch is described
as either a single poppet or dual poppet flow switch in examples
described herein.
Claims What is claimed is:
1. A flow measurement system that measures the volume of a fluid,
comprising: a control system; a turbine meter, comprising: a meter
flow path; at least one turbine rotor in said meter flow path that
rotates when fluid passes through said meter flow path; and a pulser
that sends a pulser signal in relation to the rotation of said at
least one turbine rotor to said control system; a flow switch, comprising:
a flow switch flow path; and a sensor that communicates a flow switch
signal to said control system when fluid is passing through said
flow switch flow path; said flow switch flow path fluidly coupled
to said meter flow path such that fluid that passes through said
meter flow path also passes through said flow switch flow path;
said control system receives said pulser signal and calculates a
volume of the fluid passing through said meter flow path based on
said pulser signal, wherein said control system ignores said pulser
signals in the calculation of the volume of the fluid passing through
said meter flow path when said control system is not receiving said
flow switch signal.
2. The system of claim 1 wherein said flow switch is located upstream
of said turbine meter.
3. The system of claim 1 wherein said flow switch is located downstream
of said turbine meter.
4. The system of claim 1 wherein said flow switch further comprises:
a housing; and a primary fuel flow path positioned within said housing
comprising: a piston; and a spring holding said piston in a normally
closed position.
5. The system of claim 4 wherein said sensor is adapted to sense
movement of said piston and report movement of said piston to said
control system by communicating said flow switch signal to said
control system.
6. The system of claim 5 wherein said piston further comprises
a position sensible element.
7. The system of claim 6 wherein said position sensible element
comprises a magnet and said sensor comprises a Hall-Effect sensor.
8. The system of claim 7 wherein said sensor comprises an element
selected from the group consisting of: a magnetic reed switch arrangement,
a capacitive sensor, an ultrasonic sensor, and a Hall-Effect sensor.
9. The system of claim 4 further comprising a relief valve positioned
within said housing.
10. The system of claim 9 wherein said relief valve is associated
with said piston.
11. The system of claim 1 wherein said flow switch is comprised
of: a valve body; a poppet head; an o-ring; a relief valve wherein
said relief valve is coupled between said valve body and said o-ring
and wherein said o-ring is coupled between said relief valve and
said poppet head; a washer; and a spring coupled between said poppet
head and said washer; said poppet head adapted to compress said
spring towards said washer when a force is applied to the side of
said poppet head coupled to said o-ring.
12. The system of claim 1 wherein said flow switch further comprises:
a housing; a primary fuel flow path positioned within said housing
comprising: a primary piston; and a primary spring holding said
primary piston in a normally closed position; a secondary fuel flow
path positioned within said housing, fluidly connected to said primary
fuel flow path and passing around said primary piston, said secondary
fuel flow path comprising: a secondary piston; and a secondary spring
holding said secondary piston in a normally closed position, said
secondary spring requiring less force to compress than said primary
spring.
13. The system of claim 12 wherein said sensor is adapted to sense
movement of said secondary piston and report movement of said secondary
piston to said control system.
14. The system of claim 13 wherein said secondary piston further
comprises a position sensible element.
15. The system of claim 14 wherein said position sensible element
comprises a magnet and said sensor comprises a Hall-Effect sensor.
16. The system of claim 15 wherein said sensor comprises an element
selected from the group consisting of: a magnetic reed switch arrangement,
a capacitive sensor, an ultrasonic sensor, and a Hall-Effect sensor.
17. The system of claim 12 further comprising a relief valve positioned
within said housing.
18. The system of claim 17 wherein said relief valve is associated
with said primary piston.
19. The system of claim 1 further comprising a temperature sensor
fluidly coupled to said a flow switch flow path and coupled to said
control system wherein said temperature sensor senses the temperature
of the fuel passing through said meter path and communicates the
temperature to said control system.
20. The system of claim 19 wherein said control system adjusts
the calculation of said volume of the fluid passing through said
meter flow path based on the temperature of the fluid.
21. The system of claim 1 further comprising a pressure sensor
fluidly coupled to said a flow switch flow path and coupled to said
control system wherein said pressure sensor senses the pressure
in the flow switch flow path and communicates the temperature to
said control system.
22. The system of claim 21 wherein said control system adjusts
the calculation of said volume of the fluid passing through said
meter flow path based on the pressure of the fluid.
23. The system of claim 1 further comprising a viscosity sensor
fluidly coupled to said a flow switch flow path and coupled to said
control system wherein said viscosity sensor measures the viscosity
of the fluid passing through said meter flow path and communicates
the viscosity to said control system.
24. The system of claim 23 wherein said control system adjusts
the calculation of said volume of the fluid passing through said
meter flow path based on the viscosity of the fluid.
25. The system of claim 1 further comprising an octane sensor
fluidly coupled to said a flow switch flow path and coupled to said
control system wherein said octane sensor to determine the octane
of the fluid passing through said meter flow path and communicates
the octane to said control system.
26. The system of claim 25 wherein said control system determines
if the meter flow path is contaminated based on the octane of the
fluid.
27. A fuel dispenser that measures the volume of fuel dispensed
into a vehicle, comprising: a control system; a fuel conduit that
is fluidly coupled to fuel; a valve coupled to said control system
and coupled to said fuel conduit wherein said control system controls
the opening and closing of said valve to control the flow of fuel;
a turbine meter coupled to said fuel conduit, comprising: a meter
flow path; at least one turbine rotor in said flow path that rotates
when fuel passes through said flow path; and a pulser that sends
a pulser signal in relation to the rotation of said at least one
turbine rotor to said control system; a flow switch coupled to said
fuel conduit, comprising: a flow switch flow path; and a sensor
that sends a flow switch signal to said control system when fuel
is passing through said flow switch flow path; said flow switch
flow path fluidly coupled to said meter flow path such that fuel
that passes through said meter flow path also passes through said
flow switch flow path; said control system receives said pulser
signal and calculates a volume of the fuel passing through said
meter flow path based on said pulser signal, wherein said control
system ignores said pulser signals in the calculation of the volume
of the fuel passing through said meter flow path when said control
system is not receiving said flow switch signal.
28. The fuel dispenser of claim 27 wherein said flow switch is
located upstream of said turbine meter.
29. The fuel dispenser of claim 27 wherein said flow switch is
located downstream of said turbine meter.
30. The fuel dispenser of claim 27 wherein said flow switch further
comprises: a housing; and a primary fuel flow path positioned within
said housing comprising: a piston; and a spring holding said piston
in a normally closed position.
31. The fuel dispenser of claim 30 wherein said sensor is adapted
to sense movement of said piston and report movement of said piston
to said control system by communicating said flow switch signal
to said control system.
32. The fuel dispenser of claim 31 wherein said piston further
comprises a position sensible element.
33. The fuel dispenser of claim 32 wherein said position sensible
element comprises a magnet and said sensor comprises a Hall-Effect
sensor.
34. The fuel dispenser of claim 33 wherein said sensor comprises
an element selected from the group consisting of: a magnetic reed
switch arrangement, a capacitive sensor, an ultrasonic sensor, and
a Hall-Effect sensor.
35. The fuel dispenser of claim 30 further comprising a relief
valve positioned within said housing.
36. The fuel dispenser of claim 35 wherein said relief valve is
associated with said piston.
37. The fuel dispenser of claim 27 wherein said flow switch is
comprised of: a valve body; a poppet head; an o-ring; a relief valve
wherein said relief valve is coupled between said valve body and
said o-ring and wherein said o-ring is coupled between said relief
valve and said poppet head; a washer; and a spring coupled between
said poppet head and said washer; said poppet head adapted to compress
said spring towards said washer when a force is applied to the side
of said poppet head coupled to said o-ring.
38. The fuel dispenser of claim 27 wherein said flow switch further
comprises: a housing; a primary fuel flow path positioned within
said housing comprising: a primary piston; and a primary spring
holding said primary piston in a normally closed position; a secondary
fuel flow path positioned within said housing, fluidly connected
to said primary fuel flow path and passing around said primary piston,
said secondary fuel flow path comprising: a secondary piston; and
a secondary spring holding said secondary piston in a normally closed
position, said secondary spring requiring less force to compress
than said primary spring.
39. The fuel dispenser of claim 38 wherein said sensor is adapted
to sense movement of said secondary piston and report movement of
said secondary piston to said control system.
40. The fuel dispenser of claim 39 wherein said secondary piston
further comprises a position sensible element.
41. The fuel dispenser of claim 40 wherein said position sensible
element comprises a magnet and said sensor comprises a Hall-Effect
sensor.
42. The fuel dispenser of claim 41 wherein said sensor comprises
an element selected from the group consisting of: a magnetic reed
switch arrangement, a capacitive sensor, an ultrasonic sensor, and
a Hall-Effect sensor.
43. The fuel dispenser of claim 38 further comprising a relief
valve positioned within said housing.
44. The fuel dispenser of claim 43 wherein said relief valve is
associated with said primary piston.
45. The fuel dispenser of claim 27 further comprising a temperature
sensor fluidly coupled to said a flow switch flow path and coupled
to said control system wherein said temperature sensor senses the
temperature of the fuel passing through said meter path and communicates
the temperature to said control system.
46. The fuel dispenser of claim 45 wherein said control system
adjusts the calculation of said volume of the fuel passing through
said meter flow path based on the temperature of the fuel.
47. The fuel dispenser of claim 27 further comprising a pressure
sensor fluidly coupled to said a flow switch flow path and coupled
to said control system wherein said pressure sensor senses the pressure
in the flow switch flow path and communicates the temperature to
said control system.
48. The fuel dispenser of claim 27 wherein said control system
adjusts the calculation of said volume of the fuel passing through
said meter flow path based on the pressure of the fuel.
49. The fuel dispenser of claim 27 further comprising a viscosity
sensor fluidly coupled to said a flow switch flow path and coupled
to said control system wherein said viscosity sensor measures the
viscosity of the fuel passing through said meter flow path and communicates
the viscosity to said control system.
50. The fuel dispenser of claim 49 wherein said control system
adjusts the calculation of said volume of the fuel passing through
said meter flow path based on the viscosity of the fuel.
51. The fuel dispenser of claim 27 further comprising an octane
sensor fluidly coupled to said a flow switch flow path and coupled
to said control system wherein said octane sensor to determine the
octane of the fuel passing through said meter flow path and communicates
the octane to said control system.
52. The fuel dispenser of claim 51 wherein said control system
determines if the meter flow path is contaminated based on the octane
of the fuel.
53. The fuel dispenser of claim 27 wherein said control system
displays the volume of the fuel on a display.
54. The fuel dispenser of claim 27 wherein said control system
calculates a price to be charged for the fuel and wherein said control
system displays the price on a price display.
55. A method of determining the volume of a fluid, comprising the
steps of: passing the fluid through across at least one turbine
rotor in a turbine meter causing said at least one turbine rotor
to rotate; generating a pulser signal in response to the rotation
of said turbine rotor; passing the fluid through a flow switch;
generating a flow switch signal only in response to fluid passing
through said flow switch; and using said pulser signal to calculate
the volume of the fluid based on the rate of said pulser signal
if said flow switch signal is generated in said step of generating
a flow switch signal.
56. The method of claim 55 wherein said step of generating a flow
switch signal comprises sensing the movement of a piston in a flow
switch housing that moves in response to fluid passing through said
flow switch housing.
57. The method of claim 56 further comprising: sensing movement
of said piston; and reporting movement of said piston to a control
system by communicating said flow switch signal to said control
system.
58. The method of claim 57 wherein said step of sensing said piston
comprises sensing a position sensible element on said piston.
59. The method of claim 56 further comprising releasing a relief
valve in said flow switch housing if said flow switch becomes over-pressurized.
60. The method of claim 55 further comprising sensing the temperature
of the fluid and using the temperature of the fluid to adjust the
calculation of the volume of the fluid.
61. The method of claim 55 further comprising sensing the pressure
inside said flow switch housing and using the pressure inside said
flow switch housing to adjust the calculation the volume of the
fluid.
62. The method of claim 55 further comprising sensing the viscosity
of the fluid and using the viscosity of the fluid to adjust the
calculation of the volume of the fluid.
63. The method of claim 55 further comprising sensing the octane
of the fluid and using the octane of the fluid to determine if any
contamination is pressure in said turbine meter.
64. A method of determining the volume of fuel dispensed into a
vehicle, comprising the steps of: passing fuel across at least one
turbine rotor in a turbine meter causing said at least one turbine
rotor to rotate; generating a pulser signal in response to the rotation
of said turbine rotor; passing the fuel through a flow switch; generating
a flow switch signal only in response to fuel passing through said
flow switch; using said pulser signal to calculate the volume of
the fuel based on the rate of said pulser signal if said flow switch
signal is generated in said step of generating a flow switch signal;
and displaying the volume of the fuel dispensed on a volume display.
65. The method of claim 64 wherein said step of generating a flow
switch signal comprises sensing the movement of a piston in a flow
switch housing that moves in response to fluid passing through said
flow switch housing.
66. The method of claim 65 further comprising: sensing movement
of said piston; and reporting movement of said piston to a control
system by communicating said flow switch signal to said control
system.
67. The method of claim 66 wherein said step of sensing said piston
comprises sensing a position sensible element on said piston.
68. The method of claim 65 further comprising releasing a relief
valve in said flow switch housing if said flow switch becomes over-pressurized.
69. The method of claim 64 further comprising sensing the temperature
of the fluid and using the temperature of the fluid to adjust the
calculation of the volume of the fluid.
70. The method of claim 64 further comprising sensing the pressure
inside said flow switch housing and using the pressure inside said
flow switch housing to adjust the calculation the volume of the
fluid.
71. The method of claim 64 further comprising sensing the viscosity
of the fluid and using the viscosity of the fluid to adjust the
calculation of the volume of the fluid.
72. The method of claim 64 further comprising sensing the octane
of the fluid and using the octane of the fluid to determine if any
contamination is pressure in said turbine meter.
73. A method of determining the volume of fuel dispensed into a
vehicle, comprising the steps of: initiating the dispensing of fuel;
opening partially a two-stage valve adapted to regulate fuel flow
into a flow rate selected from the group consisting of: no flow,
slow flow and high flow; measuring the flow rate of the fuel; generating
pulser signals indicative of the flow rate of the fuel; compressing
a secondary spring in a secondary piston in a dual piston valve
to open a secondary fuel path; detecting movement of a sensible
element in said dual piston valve when said secondary piston moves;
communicating the movement of said secondary piston; using said
pulser signal to calculate the volume of the fuel based on the rate
of said pulser signal; dispensing the fuel in a slow flow state;
opening fully said two-stage valve; compressing a primary spring
in a primary piston in said dual piston valve to open a primary
fuel path; dispensing the fuel in a high flow state; closing partially
said two-stage valve when the volume of the fuel approaches a pre-paid
amount; decompressing said primary spring to close same primary
fuel path; closing said two-stage valve; decompressing said secondary
spring to close said secondary fuel path; communicating a movement
of said sensible element after said step of decompressing; and ignoring
said pulser signal after said steps of decompressing and communicating
a movement of said sensible element to said control system after
said step of decompressing.
Description FIELD OF THE INVENTION
The present invention relates to a device, system and method for
determining accurately the volume of fuel flow dispensed by a fuel
dispenser.
BACKGROUND OF THE INVENTION
In a typical transaction, a consumer may drive a vehicle up to
a fuel dispenser in a fueling environment. The consumer arranges
for payment, either by paying at the pump, paying the cashier with
cash, using a credit card or debit card, or some combination of
these methods. The nozzle is inserted into the fill neck of the
vehicle, and fuel is dispensed into the gas tank of the vehicle.
Displays on the fuel dispenser display how much fuel has been dispensed
as well as a dollar value associated with the fuel that has been
dispensed. The customer relies on the fuel dispenser to measure
the amount of fuel dispensed accurately and charge the customer
accordingly. One method customers sometimes use to control costs
is to pay for a preset amount of fuel based on a dollar or volume
amount, called a "pre-pay". Regulatory requirements, namely
Weights & Measures, require that these customers receive all
of the fuel for which they have paid to a highly accurate degree.
Operating behind the scenes of this process are valves that open
and close the fuel flow path and a flow meter that measures the
amount of fuel dispensed inside the fuel dispenser. The purpose
of the flow meter is to measure accurately the amount of fuel being
delivered to the customer's vehicle so that the customer may be
billed accordingly and fuel inventory tracking may be undertaken.
As noted, for preset dollar or volume transactions (pre-pays), the
fuel dispenser relies on the flow meter to measure the fuel dispensed
so as to know when to terminate the fuel flow.
Some fuel dispenser fuel flow meters are inferential meters, meaning
that the actual displacement of the fuel is not measured. Inferential
meters have some advantages over positive displacement meters. Chief
among these advantages is that inferential meters typically are
smaller than positive displacement meters. One example of an inferential
meter that may be used is described in U.S. Pat. No. 5689071
entitled "WIDE RANGE, HIGH ACCURACY FLOW METER." The '071
patent describes a turbine flow meter that measures the flow rate
of a fluid by determining the number of rotations of turbine rotors
located inside the flow path of the meter.
As fluid enters the inlet port of the turbine flow meter in the
'071 patent, the fluid passes across two turbine rotors, which causes
the turbine rotors to rotate. The rotational velocity of the turbine
rotors is sensed by pick-off coils. The pick-off coils are excited
by an alternating current signal that produces a magnetic field.
As the turbine rotors rotate, the vanes on the turbine rotors pass
through the magnetic field generated by the pick-off coils, thereby
superimposing a pulse on the carrier waveform of the pick-off coils.
The superimposed pulses occur at a repetition rate (pulses per second)
proportional to the rotors'velocity and hence proportional to the
measured rate of flow.
A problem may occur when using a turbine flow meter to measure
fuel in a retail fuel dispenser. When fuel flows across the rotors,
the rotors acquire rotational momentum. When the fuel flow stops,
the rotational momentum causes the turbine rotors to continue to
rotate for a period of time thereafter despite the absence of fuel
flow. This continued movement causes the turbine flow meter to continue
generating measurement signals as if fuel were still flowing. The
control system that receives the measurement signals from the pick-off
coils of the turbine flow meter continues to register fuel flow
falsely.
Therefore, a need exists for a fuel dispenser to measure accurately
fuel flow with a fuel flow meter that continues to generate measurement
signals even after fuel flow has stopped.
SUMMARY OF THE INVENTION
The present invention is directed to a flow switch that operates
in a fuel dispenser to detect and communicate when fuel is flowing
in the fuel dispenser and being delivered to a vehicle. For certain
types of fuel flow meters used in fuel dispensers, the flow meter
may continue to indicate a signal or indicia indicative of fuel
flow after fuel flow has stopped. In this manner, a fuel dispenser
will continue to operate as if fuel is being dispensed to a customer's
vehicle when fuel has indeed stopped. This will cause the number
of gallons dispensed as well as the price charged to the customer
for such fuel to be inaccurate. Therefore, the present invention
is directed to a device, system, and method to accurately measure
fuel flow in a fuel dispenser by determining when fuel flow has
stopped in the event that the fuel flow meter continues to indicate
fuel flow.
In one embodiment of the present invention, the fuel flow meter
of the fuel dispenser is a turbine flow meter like that described
in the '071 Patent referenced in the Background of the Invention.
After fuel exits the shear valve in the fuel dispenser, the fuel
enters the fuel flow meter. A flow switch is located downstream
of the fuel flow meter so that a control system in the fuel dispenser
has knowledge of when fuel flow is actually occurring in the fuel
dispenser and when it is not. Alternatively, the flow switch could
be located on the inlet side of the fuel flow meter either proximate
to the fuel flow meter or before other components on the inlet side
of the fuel flow meter.
The flow switch may be comprised of a housing, within which the
components and various elements of the flow switch are located,
and also to create a fuel flow path for fuel to flow from the fuel
flow meter. As fuel enters the flow switch, the fuel may first encounter
an optional flow straightener. After fuel exits the flow straightener,
the fuel encounters a valve in the flow switch that moves in response
to the force of the fuel. The flow switch includes a signaling means
to inform the control system when fuel is flowing and when fuel
is not flowing. The control system can ignore fuel flow pulse signals
from the fuel flow meter as part of the calculation of the flow
rate and/or volume of fuel being dispensed when the flow switch
indicates that fuel is not flowing.
In one embodiment of the present invention, the flow switch is
a single poppet valve that is incorporated into a flow switch housing.
The poppet valve contains a spring to form a spring-loaded housing
such that the force of fuel flow applies pressure to the spring
and causes an indicator or sensor coupled to the poppet valve to
generate a signal over a sensor communication line to the control
system. In this manner, the control system detects when fuel is
flowing through the flow switch for the purposes of accurately measuring
the flow rate and/or volume of fuel flow. In exemplary embodiments,
the indicator may be a Hall Effect sensor, an ultrasonic sensor,
a magnetic reed switch, or the like, so as to help track the movement
of the poppet. After the fuel flow exits flow switch, the fuel flow
may encounter an additional optional flow straightener as was previously
described. After the fuel exits the flow switch, the fuel is eventually
dispensed to a hose and nozzle and onto a vehicle. The valve can
also acts as a check valve to allow fuel to only flow in one direction
thereby preventing backflow.
In another embodiment, a dual piston/poppet is used as the flow
switch. The dual piston/poppet acts as a valve and includes two
poppets to handle both slow fuel flow and high fuel flow conditions
in the fuel dispenser to accurately determine when fuel is flowing
and when fuel is not flowing. A single poppet flow switch may not
be able to properly determine when fuel is flowing and when fuel
is not flowing for both slow fuel flow and high fuel flow conditions.
Slow fuel flow conditions exist at the beginning of a dispensing
transaction and when the fuel dispenser slows down fuel delivery
during a pre-pay transaction to deliver an exact amount of fuel
according to the amount of the pre-pay. This alternative valve also
acts as a check valve.
The dual piston/poppet valve operates in one of three modes. The
first mode is the fully closed mode where both pistons are closed
and no fuel flows through the valve. The second mode is a slow flow
open mode. In this mode, a secondary or bypass fuel path is open
and fuel flows relatively slowly through the valve. The indicator,
if present, tells the control system that the bypass fuel path is
open and thus, the control system knows to accept inputs from the
flow meter as non-spurious. The third mode is a high flow open mode.
In this mode, a primary fuel path is open concurrently with the
secondary fuel path, and fuel flows quickly through the valve. Because
the secondary fuel path is open, the indicator, if present, tells
the control system to accept input from the flow meter. The two-fuel
path arrangement helps optimize the valve for use with an inferential
flow meter in slow flow and high flow situations regardless of the
existence of the indicator. The indicator helps the control system
of the fuel dispenser know when to accept inputs from the flow meter.
The valve has a housing with a primary fuel flow path on a primary
axis of the housing. The primary fuel flow path is blocked by a
normally closed primary piston. The primary piston is kept normally
closed by a primary spring. A secondary fuel flow path routes around
the primary piston. The secondary fuel flow path is blocked by a
normally closed secondary piston. The secondary piston is likewise
kept normally closed by a secondary spring. The force required to
open the secondary piston is comparatively less than that required
to open the primary piston. The secondary piston is also connected
to a magnet or other position sensible element that acts as the
indicator such that movements of the secondary piston may be detected.
In use, the valve initially receives fuel at a slow rate. This
fuel hits the primary piston and is blocked. The fuel is thus shunted
into the secondary fuel flow path where the fuel encounters the
secondary piston. The secondary spring on the secondary piston is
weak enough such that the slow rate of fuel is sufficient to compress
the secondary spring, thereby opening the secondary fuel flow path.
Opening the secondary piston moves the position sensible element
such that a sensor may detect the movement of the position sensible
element. The rate of fuel flow increases until the pressure on the
primary piston is enough to compress the primary spring, thereby
opening the primary fuel flow path. Fuel then flows through both
the primary fuel path and the secondary fuel path during the majority
of the fueling transaction.
As the fueling transaction ends, the process is reversed. The fuel
flow rate slows, lowering the pressure on the primary piston. The
primary spring closes the primary piston, leaving the secondary
fuel path open. When the fuel flow is terminated, such as at the
end of the transaction, the pressure on the secondary piston abates,
and the secondary spring closes the secondary piston. The closing
of the secondary piston moves the position sensible element, and
the control system is informed to ignore further signals from the
flow meter. Even when fuel flow is terminated abruptly and both
pistons close at the same time, the movement of the position sensible
element informs the control system to ignore further signals from
the flow meter.
In exemplary embodiments, the indicator may be a Hall-Effect sensor,
an ultrasonic sensor, a magnetic reed switch, or the like, so as
to help track the movement of the secondary piston. Flow straigteners
may also be included on both the inlet and/or outlet sides of the
dual poppet valve flow switch.
Those skilled in the art will appreciate the scope of the present
invention and realize additional aspects thereof after reading the
following detailed description of the preferred embodiments in association
with the accompanying drawing figures.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawing figures incorporated in and forming a
part of this specification illustrate several aspects of the invention,
and together with the description serve to explain the principles
of the invention.
FIG. 1 illustrates a fuel dispenser involved in a fueling transaction
in the prior art;
FIG. 2 illustrates a partial front view of a fuel dispenser in
the prior art;
FIG. 3 illustrates a schematic diagram of a first embodiment of
the fuel flow components of the fuel dispenser;
FIG. 4 illustrates a schematic diagram of a second embodiment of
the fuel flow components of the fuel dispenser;
FIG. 5 illustrates a schematic diagram of the meter and flow switch
according to one embodiment of the present invention;
FIG. 6 illustrates a schematic diagram of a turbine flow meter
that may be used as the fuel flow meter for the present invention;
FIG. 7A illustrates a schematic diagram of one embodiment of a
flow switch in accordance with one embodiment of the present invention;
FIG. 7B illustrates a schematic diagram of another embodiment of
a flow switch in accordance with one embodiment of the present invention;
FIG. 8A illustrates a schematic diagram of a single poppet valve
flow switch in a closed position when fuel is not flowing;
FIG. 8B illustrates a schematic diagram of a single poppet valve
flow switch in an open position when fuel is flowing;
FIG. 9 illustrates an exploded view of the single poppet valve
illustrated in FIGS. 8A and 8B and used at the flow switch in FIG.
7;
FIGS. 10A and 10B illustrate a flowchart diagram of one embodiment
of the operation of the flow switch and control system to determine
the flow rate and/or volume of fuel dispensed;
FIG. 11A illustrates a dual poppet embodiment of a flow switch
in a first, closed position in accordance with another embodiment
of the present invention;
FIG. 11B illustrates the dual poppet flow switch illustrated in
FIG. 11A in a second, partially open position;
FIG. 11C illustrates the dual poppet flow switch illustrated in
FIG. 11A in a third, fully open position; and
FIGS. 12A and 12B illustrate a flowchart diagram of another embodiment
of the operation of the flow switch and control system to determine
the flow rate and/or volume of fuel dispensed using the flow switch
illustrated in FIGS. 11A-11C.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The embodiments set forth below represent the necessary information
to enable those skilled in the art to practice the invention and
illustrate the best mode of practicing the invention. Upon reading
the following description in light of the accompanying drawing figures,
those skilled in the art will understand the concepts of the invention
and will recognize applications of these concepts not particularly
addressed herein. It should be understood that these concepts and
applications fall within the scope of the disclosure and the accompanying
claims.
The present invention is directed to a flow switch that operates
in a fuel dispenser to detect and communicate when fuel is flowing
in the fuel dispenser and being delivered to a vehicle. For certain
types of fuel flow meters used in fuel dispensers, the flow meter
may continue to indicate a signal or indicia indicative of fuel
flow after fuel flow has stopped. In this manner, a fuel dispenser
will continue to operate as if fuel is being dispensed to a customer's
vehicle when fuel has indeed stopped. This will cause the number
of gallons dispensed as well as the price charged to the customer
for such fuel to be inaccurate. Therefore, the present invention
is directed to a device, system, and method to accurately measure
fuel flow in a fuel dispenser by determining when fuel flow has
stopped in the event that the fuel flow meter continues to indicate
fuel flow. In the main embodiment of the present invention, a turbine
flow meter is described as the fuel flow meter of the fuel dispenser.
A discussion of the fuel flow meter in combination with a flow switch
according to the invention is discussed beginning at FIG. 5 below.
Before these aspects of the present invention are described, some
background information of typical fuel dispensers and their components
is described first as illustrated in FIGS. 1-4.
FIG. 1 illustrates a typical fueling environment 10 with a vehicle
12 being fueled by a fuel dispenser 14. The fuel dispenser 14 includes
a housing 16 with a hose 18 extending therefrom. The hose 18 terminates
in a manually operated nozzle 20 adapted to be inserted into a fill
neck 22 of the vehicle 12. Fuel flows from an underground storage
tank (UST) (not illustrated) through the fuel dispenser 14 out
through the hose 18 down the fill neck 22 to a fuel tank 24 of
the vehicle 12 as is well understood. The fuel dispenser 14 may
be the ECLIPSE.RTM. or ENCORE.RTM. sold by assignee of the present
invention or other fuel dispensers as needed or desired such as
that embodied in U.S. Pat. No. 4978029 which is hereby incorporated
by reference in its entirety.
The front of the fuel dispenser 14 is illustrated in FIG. 2. The
fuel dispenser 14 may have an advertising display 26 proximate the
top of the housing 16 and a video display 28 at eye level. The video
display 28 may be the Infoscreen.RTM. manufactured and sold by Gilbarco
Inc. The video display 28 may be associated with auxiliary information
displays relating to an ongoing fuel transaction that includes the
number of gallons of fuel dispensed displayed on a gallons display
30 and the price of such fuel dispensed on a price display 32.
The displays 26 28 30 32 may include the capability of displaying
streaming video and may include liquid crystal displays (LCDs) as
needed or desired.
The present invention is well suited for use inside the housing
16 of a fuel dispenser 14. Specifically, the present invention is
well suited for positioning in the fuel path of the fuel dispenser
14 as better illustrated in FIG. 3. Fuel may travel from the UST
(not illustrated) via a fuel pipe 36 which may be a double-walled
pipe. An exemplary underground fuel delivery system is illustrated
in U.S. Pat. No. 6435204 which is hereby incorporated by reference
in its entirety. The fuel pipe 36 may pass into the housing 16 first
through a shear valve 38. The shear valve 38 is designed to cut
off fuel flowing through the fuel pipe 36 if the fuel dispenser
14 is impacted, as is commonly known in the industry. One illustration
of a shear valve 38 is disclosed in U.S. Pat. No. 6575206 which
is hereby incorporated by reference in its entirety.
In most fuel dispensers 14 a submersible turbine pump (STP) (not
illustrated) associated with the UST is used to pump fuel to the
fuel dispenser 14. Some fuel dispensers 14 may be self-contained,
meaning fuel is drawn to the fuel dispenser 14 by a pump controlled
by a motor (neither shown) positioned within the housing 16. A valve
40 may be positioned upstream of a fuel flow meter 52. Alternatively,
the valve 40 may be positioned downstream of the flow meter 52 (see
FIG. 4). The fuel flow meter 52 and valve 40 are positioned in a
fuel handling compartment 44 of the housing 16 as is well understood.
The fuel handling compartment 44 is isolated from an electronics
compartment 46 located above a vapor barrier 42. The fuel handling
compartment 44 is isolated from any sparks or other events that
may cause combustion of fuel vapors as is well understood and as
is described in U.S. Pat. No. 5717564 which is hereby incorporated
by reference in its entirety.
The flow meter 52 and valve 40 communicate through the vapor barrier
42 to a control system 48 that is typically positioned within the
electronics compartment 46 of the fuel dispenser 14. Another example
of a two-chambered fuel dispenser 14 is described in U.S. Pat. No.
4986445 which is hereby incorporated by reference in its entirety.
The control system 48 may be a microcontroller, a microprocessor,
or other electronics with associated memory and software programs
running thereon as is well understood. The control system 48 typically
controls other aspects of the fuel dispenser 14 such as the displays
26 28 30 32 and the like, as is well understood.
The control system 48 directs the valve 40 via a valve communication
line 50 to open and close when fuel dispensing is desired or not
desired. The valve 40 may be a proportional solenoid controlled
valve, such as described in U.S. Pat. No. 5954080 for example,
which is incorporated herein by reference in its entirety. If the
control system 48 directs the valve 40 to open to allow fuel to
flow to be dispensed, the fuel enters the valve 40 and exits into
the fuel flow meter 52. The volumetric flow rate of the fuel is
measured by the fuel flow meter 52 and the fuel flow meter 52 communicates
the volumetric flow rate of the fuel to the control system 48 via
a pulser signal 54. In this manner, the control system 48 uses the
pulser signal 54 to determine the volume of fuel flowing through
the fuel dispenser and being delivered to a vehicle 12. The control
system 48 updates the total gallons dispensed on the gallons display
30 via the gallons display communication line 56 and the price
of fuel dispensed on the price display 32 via price display communication
line 58.
In the embodiment illustrated in FIG. 3 as fuel leaves the fuel
flow meter 52 fuel enters a flow switch 60. The flow switch 60
generates a flow switch communication signal via the flow switch
communication line 62 to the control system 48 to communicate when
fuel is flowing through the fuel flow meter 52. After the fuel enters
the flow switch 60 it exits through the fuel conduit 55 to be delivered
to the hose 18 and nozzle 20 for eventual delivery into the fuel
tank 24 of a vehicle 12. Although the control system 48 controls
the opening and closing of valve 40 to allow fuel to flow or not
flow, the control system 48 cannot guarantee that fuel is flowing
through the fuel dispenser 14 just because the control system 48
has directed the valve 40 to be open.
If the fuel flow meter 52 continues to register volumetric flow
of fuel via generation of the pulser signal 54 even after fuel flow
has stopped, the control system 48 by receipt of the flow switch
signal via flow switch communication line 62 will know whether
fuel flow is indeed flowing through the fuel flow meter 52 or not.
If fuel is not flowing through the fuel flow meter 52 even though
the control system 48 is continuing to receive the pulser signal
54 the control system 48 can ignore the pulser signal 54 so that
the number of gallons of fuel dispensed and the price of such fuel
dispensed does not incorporate extraneous and erroneous additional
pulses from the pulser signal 54. The remainder of this patent application
will discuss more detailed aspects of the fuel flow switch 60 and
its interaction with the control system 48 to allow the control
system 48 to determine if fuel is flowing through the fuel dispenser
14 and to use this information to accurately measure fuel being
dispensed to a vehicle 12.
FIG. 4 is an illustration of a fuel dispenser 14 similar to that
illustrated in FIG. 3. However, in FIG. 4 the fuel flow meter 52
and the valve 40 are rearranged. In FIG. 4 after fuel exits the
shear valve 38 the fuel enters the fuel flow meter 52 first and
then enters into the valve 40. This embodiment can also be used
as well as the embodiment in FIG. 3 to perform the present invention.
The control system 48 is still able to control fuel flow by the
opening and closing of the valve 40 in this embodiment. Again, in
this embodiment, the flow switch 60 is located downstream of the
fuel flow meter 52 and valve 40 so that the control system 48 has
knowledge of when fuel flow is actually occurring in the fuel dispenser
and when it is not. Although not illustrated, the flow switch 60
could also be located on the inlet side of the fuel flow meter 52
either proximate to the fuel flow meter 52 or before other components
on the inlet side of the fuel flow meter 52.
FIG. 5 illustrates a block diagram of the present invention and
of the components that are illustrated in FIG. 3. As previously
discussed, the flow switch 60 indicates to the control system 48
when fuel is flowing through the fuel flow meter 52 and when it
is not so that the control system 48 can ignore any extraneous and
erroneous pulser signals 54. FIG. 5 illustrates the pulser 59 that
generates the pulser signal 54 to the control system 48. The pulser
59 may be incorporated into the fuel flow meter 52 or may be external
to the fuel flow meter 52. The other aspects of FIG. 5 are just
as previously described above for FIG. 3.
FIG. 6 illustrates one particular type of fuel flow meter 52 that
may be used in the present invention. This fuel flow meter 52 is
called a "turbine" fuel flow meter 52. An example of a
turbine fuel flow meter 52 is described in U.S. Pat. No. 5689071
previously referenced in the background of the invention above,
and hereby incorporated by reference herein in its entirety. The
turbine fuel flow meter 52 is comprised of a meter housing 64 that
is typically constructed out of a high permeable material such as
monel, a nickel-copper alloy, stainless steel, or 300-series non-magnetic
stainless steel, for example. The meter housing 64 forms a cylindrical
hollow shape that forms an inlet and outlet for fuel to flow through
the turbine fuel flow meter 52. A shaft 72 is placed internal to
the meter housing 64 to support one or more turbine rotors 70 71.
In the present example, two turbine rotors are illustrated; a first
turbine rotor 70 and a second turbine rotor 71 but only one turbine
rotor 70 may be used as well.
The turbine rotors 70 71 rotate in an axis perpendicular to the
axis of the shaft 72. The turbine rotors 70 71 contain one or more
vanes 68 also known as blades. As fuel passes through the inlet
of the turbine fuel flow meter 52 and across the vanes 68 of the
turbine rotors 70 71 the turbine rotors 70 71 and the vanes 68
rotate at a speed proportional to the rate of flow of the fuel flowing
through the turbine fuel flow meter 52. The proportion of the rotational
speed of the first turbine rotor 70 to the second turbine rotor
71 is determined by counting the vanes 68 passing by the pickoff
coils 73 74. The speed of the turbine rotors 70 71 can be used
to determine the flow rate of fuel passing through the turbine fuel
flow meter 52 as is described in the aforementioned U.S. Pat. No.
5689071 and in U.S. Pat. No. 5831176 which are hereby incorporated
by reference in their entireties.
In the present example, there are two pickoff coils--a first pickoff
coil 73 placed proximate to the first turbine rotor 70 and a second
pickoff coil 74 placed proximate to the second turbine rotor 71.
It is noted that the turbine fuel flow meter 52 can be provided
with only one turbine rotor 70 to detect flow rate as well. Also,
the meter housing 64 may be comprised of two different permeable
materials such as described in U.S. patent application Ser. No.
10/227746 entitled "Multi-metal turbine sensing for increased
sensitivity and reduced cost," incorporated herein by reference
in its entirety.
The pickoff coils 73 74 generate a magnetic signal that penetrates
through the permeable meter housing 64 to reach the vanes 68. As
the turbine rotors 70 71 rotate, the vanes 68 superimpose a pulser
signal 54 on the magnetic signal generated by the pickoff coils
73 74. The pulser signal 54 is analyzed by the control system 48
to determine the speed of the vanes 68 that in turn can be used
to calculate the flow rate and/or volume of fuel flowing through
the turbine fuel flow meter 52. After fuel flow stops flowing through
the turbine fuel flow meter 52 the turbine rotors 70 71 may continue
to rotate due to their rotational momentum. In this instance, the
vanes 68 continue to superimpose a signal on the pick-off coils
73 74 thereby generating pulser signals 54. These pulser signals
54 are communicated to the control system 48. The control system
48 will use the pulser signals 54 to determine the flow rate and/or
volume of fuel erroneously since fuel was not flowing unless the
control system 48 has a method of determining that fuel is not flowing
during this time independent of the pulser signal 54. The flow switch
60 of the present invention accomplishes this function.
In the embodiment illustrated in FIG. 6 it should be noted that
in an alternative embodiment of the present invention when only
one turbine rotor 70 is used, only one pickoff coil 73 may be used
as well. Also, more than one pickoff coil 73 74 may be used for
any one turbine rotor 70 so that the pickoff coils 73 74 can determine
the direction of the rotation of the turbine rotor 70 as well as
its speed.
FIG. 7A illustrates one embodiment of a flow switch 60 according
to the present invention wherein the flow switch 60 is located downstream
of the fuel flow meter 52. The flow switch 60 may be comprised of
a housing 76 within which the components and various elements of
the flow switch 60 are located, and also to create a fuel flow path
for fuel to flow from the turbine fuel flow meter 52 and/or valve
40. As fuel enters the flow switch 60 from the left-hand side of
FIG. 7 the fuel will first encounter a flow straightener 78. The
flow straightener 78 in this embodiment is comprised of a cylindrical
member with cross members 80. In this manner, as fuel flows across
the flow straightener 78 it encounters the cross members 80 so
that any turbulence in the fuel flow is minimized before the fuel
reaches the other components of the flow switch 60. A flow straightener
78 is used to ensure that turbulence is minimized in the fuel flow
to provide a consistent force of the fuel being applied to the flow
switch 60 as will be later described. Typically, turbine flow meters
in particular cannot handle turbulent flow conditions such as vortexes.
Laminar flow conditions may be required, and the flow straightener
78 aids in providing such laminar flow conditions.
After fuel exits the flow straightener 78 it may encounter a pressure
sensor 82 a temperature sensor 86 and/or an octane sensor 90.
Inserting a flow straightener 78 on the inlet side of the flow switch
60 performs the function of inlet conditioning of the fluid if the
fuel flow meter 52 is downstream of the valve 94. Optimal placement
of the flow straightener 78 on the inlet side of the poppet valve
94 is a distance of approximately five times the internal diameter
of the flow switch 60 fuel flow path noted as "d" in FIG.
7A from the poppet valve 94 but other distances may be used as
designed and desired.
If a pressure sensor 82 temperature sensor 86 and/or octane sensor
90 are provided in a flow switch 60 these sensors are placed such
that they are coupled to the internal fuel flow path of the flow
switch 60. The pressure sensor 82 temperature sensor 86 and an
octane sensor 90 are electronically coupled to the control system
48 via a pressure sensor communication line 84 a temperature sensor
communication line 88 and an octane sensor communication line 92
respectively. In this manner, control system 48 can measure the
pressure, temperature, and/or octane of the fuel flow for various
reasons. The pressure inside the flow switch 60 may be used to determine
pressure drop for system diagnostics purposes. The temperature of
the fuel flowing through the flow switch 60 may be used by the control
system 48 to determine the density and/or viscosity of the fuel
for adjusting the volume throughput of fuel through the fuel flow
meter 52 including but not limited to temperature compensation,
and/or make corrections for thermal expansion of meter fuel flow
meter 52. The octane of the fuel flow passing through the flow switch
60 may be used by the control system 48 to detect and alert octane
variations and/or presence of wrong fuel in the line.
Next, after the fuel flow leaves the flow straightener 78 the
fuel flow encounters a poppet valve 94 that is incorporated into
the flow switch housing 76 and acts as the flow switch 60 in one
embodiment of the present invention. The poppet valve 94 contains
a spring 96 to form a spring-loaded housing such that the force
of fuel flow applies pressure to the spring 96 and causes a sensor
98 coupled to the poppet valve 94 to generate a signal over a sensor
communication line 100 to the control system 48. In this manner,
the control system 48 detects when fuel is flowing through the flow
switch 60 for the purposes previously described and later described
in this application.
FIG. 7B illustrates an alternative embodiment of the embodiment
illustrated in FIG. 7A where the flow switch 60 is located upstream
of the fuel flow meter 52. The discussion of FIG. 7A is equally
applicable to this embodiment and is incorporated herein by reference
in its entirety. In this embodiment, the flow straightener 78 is
shown on the outlet side of the poppet valve 94 which also serves
as a flow straightener 78 for the inlet of the fuel flow meter 52.
The flow straightener 78 serves the same purposes as described above
in FIG. 7A. Optimal placement of the flow straightener 78 on the
outlet side of the poppet valve 94 is a distance of approximately
ten times the internal diameter of the flow switch 60 fuel flow
path noted as "d" in FIG. 7B from the poppet valve 94
to the inlet of the fuel flow meter 52 but other distances may
be used as designed and desired.
FIGS. 8A, 8B and 9 illustrate one embodiment of the flow switch
60 in the form of the poppet valve 94 as illustrated in FIG. 7.
Please note that the present invention is not limited to any one
particular design of a flow switch 60 and various other designs
may be used with the present invention. The poppet valve 94 illustrated
in FIG. 8A is comprised of a valve body 102 that forms a valve back
103. A piston 104 is located inside the valve body 102. A spring
96 is placed inside the valve body 102 between the valve back 103
and the piston 104 such that the piston 104 is spring loaded. The
piston 104 contains a poppet head 106 that abuts the front of the
valve body 102 separated by an o-ring 110 when the valve 94 is in
a normally closed position. A washer 112 is also used to separate
the spring 96 from the valve back 103. A relief valve 108 is also
coupled to the poppet head 106 so that any significant back pressure
on the valve 94 going from the valve back 103 towards the poppet
head 106 can be relieved for safety considerations. A sensor 98
is placed on the valve body 102 and is electronically coupled to
the control system 48 via the sensor communication line 100.
FIG. 8B shows the valve 94 in an open position when fuel is flowing.
When fuel encounters the poppet head 106 and applies a force significant
enough to compress the spring 96 the poppet head 106 is moved backwards
and fuel flow is allowed to enter the valve body 102 and flow around
the sides of the poppet head 106. Note that the width of the poppet
head 106 is less than the diameter of the valve body 102 so that
fuel can flow around the edges of the poppet head 106.
When the poppet head 106 moves back and encounters the same plane
as where the sensor 98 is located on the valve body 102 the sensor
98 detects the poppet head 106 and sends a signal over the sensor
communication line 100 to the control system 48. In this manner,
the control system 48 knows that fuel is flowing due to the compression
of the spring-loaded piston 104. In one embodiment, the sensor 98
is a Hall-Effect sensor 98 and the Hall-Effect sensor 98 detects
a position sensible element 113 on the poppet head 106 which is
a magnetic material in this case. The Hall-Effect sensor 98 detects
the magnet in the position sensible element 113 and generates a
signal over the sensor communication line 100 to the control system
48. The valve 94 also acts as a check valve to only allow fuel to
flow in one direction thereby preventing backflow which can cause
turbulence and inaccuracies in fuel flow measurement.
FIG. 9 illustrates an exploded view of the poppet valve 94 illustrated
in FIGS. 6 7 8A and 8B. The exploded view is self-explanatory
with the previous explanation of the components of the piston valve
94 described in FIGS. 8A and 8B.
FIGS. 10A and 10B illustrate a flow chart that describes the operation
of one embodiment of the present invention where the control system
48 uses the signal from the sensor communication line 100 to determine
when fuel is flowing and to accurately determine the volume of fuel
flowing through the fuel flow meter 52. The process starts (block
200), and the customer initiates a fueling transaction at a fuel
dispenser 14 (block 202). Next, the submersible turbine pump is
activated and fuel is pumped to the fuel dispenser 14 (block 204).
The control system 48 clears a poppet disengaged flag in memory,
since fuel flow from the STP has not yet reached the flow switch
60 to engage the flow switch 60. The control system 48 then releases
the flow switch 60 when fuel flow has stopped (block 206).
Fuel then begins to flow through the fuel dispenser 14 where it
enters the fuel flow meter 52 and the turbine rotors 70 71 of the
fuel flow meter 52. The turbine rotors 70 71 begin to rotate as
fuel passes through the fuel flow meter 52 (block 208). Fuel then
flows through the flow switch 60 and the force of the fuel flow
moves the poppet head 106 back (block 210). Next, the turbine rotor
pulser signal 54 is communicated to the control system 48 indicative
of fuel flow through the fuel flow meter 52 (block 212). The control
system 48 will determine first before analyzing the pulser signal
54 if the poppet disengaged flag is set (decision 214). If the poppet
disengaged flag is not set, the control system 48 will convert the
turbine rotor pulser signal 54 into a fuel flow rate and fuel volume
dispensed since this is indicative that fuel is flowing through
the fuel flow meter 52 and flow switch 60 and the pulser signal
54 should not be ignored (block 216).
Next, whether it is from block 216 or the poppet disengaged flag
sets being set in decision 214 the control system 48 displays the
fuel volume dispensed in terms of gallons on the gallons display
30 and the price for such fuel on the price display 32 (block 218).
The control system 48 determines if the poppet head 106 is disengaged
via the sensor 98 and the sensor communication line 100 (decision
220 in FIG. 10B). If not, this indicates fuel flow slowing through
the flow switch 60 and the poppet disengaged flag is cleared so
that the control system 48 can continue to count pulses from the
pulser signal 54 to determine the volume of fuel flow through the
fuel flow meter 52 and the fuel dispenser 14 in block 208. If the
poppet head 106 is disengaged in decision 220 the poppet disengaged
flag is set (block 222) and the process repeats by going back to
block 208. Note that, after the poppet disengaged flag is set in
block 222 the next time the control system 48 performs the operation
in decision 214 the poppet disengaged flag set decision will be
answered in the affirmative which will cause the control system
48 to skip block 216 so that the turbine rotor pulser signal 54
is not used to determine the flow rate and/or volume of fuel dispensed
since fuel is not flowing through the fuel flow meter 52.
Note that the flow chart illustrated in FIGS. 10A and 10B is just
one embodiment of the present invention and is not intended to limit
the operation of the present invention. The important function of
the system, whoever it is accomplished, is the ability of the control
system 48 to ignore pulser signals 54 when the flow switch 60 indicates
to the control system 48 that fuel is not flowing.
FIG. 11A illustrates an alternative embodiment of a flow switch
60 which is generally referred to as a dual poppet valve 120 and
which is also described in pending patent application Ser. No. 10/389377
entitled "Dual Piston/Poppet Flow Switch." A dual poppet
valve 120 may have an increased performance capability over the
single poppet valve 94 due to slow flow and high flow conditions
in a fuel dispenser 14 that also occurs in a "pre-pay"/"preset"
fueling transaction. A fuel dispenser 14 typically includes a two-staged
high flow and slow flow valve (not illustrated) so that fuel flow
can be slowed down at the end of a preset transaction when the customer
has dictated a set number of gallons or price to be paid for fuel.
When the slow flow condition exists, the force from the fuel flow
as applied to a single poppet valve 94 may not be enough force to
move the poppet head 106 back so that the position sensible element
113 is detected by the sensor 98 such that the control system 48
detects that fuel is flowing. In this instance, fuel is flowing
through the flow switch 60 but the control system 48 will not register
fuel flow and will ignore the pulser signal 54 in the calculation
of volume of fuel dispensed and the price charged to the customer,
thereby resulting in an inaccurate fuel flow measurement. Therefore,
it may be advantageous to design a flow switch 60 in the form of
a dual poppet valve 120 that is capable of operating in both high
flow and slow flow conditions.
The dual poppet valve 120 according to the embodiment illustrated
in FIG. 11A is in a closed position so that no fuel flows through
the dual poppet valve 120. The dual poppet valve 120 includes a
housing 121 that is formed from a material that does not corrode
in the presence of hydrocarbons or has been treated to avoid corrosion.
A primary piston 122 is positioned within the housing 121. The primary
piston 122 is held in its normally closed position by a primary
spring 124. An o-ring 126 may be used to help ensure a tight seal
between the primary piston 122 and the housing 121.
A secondary piston 128 is likewise present. The secondary piston
128 is held in its normally closed position by a secondary spring
130. The secondary piston 128 is positioned proximate to the housing
121 of the dual poppet valve 120 and is used to sense the position
of the position sensible element 132. The sensor 98 communicates
with the control system 48 to indicate the position of the secondary
piston 128. In an exemplary embodiment, the position sensible element
132 is a magnet in the sensor 98 is a Hall-Effect sensor, like that
previously described for the single poppet valve 94 illustrated
in FIGS. 7-9. Alternative position sensible element 132/sensor 98
combinations include, but are not necessarily limited to: magnetic
read switches, ultrasonic, in capacitive combinations.
The dual poppet valve 120 will be in the fully-closed position
illustrated in FIG. 11A when no fuel is flowing. In a preferred
embodiment, the force required to compress the secondary spring
130 is lower than the force required to compress the primary spring
124. Specifically, the secondary spring 130 is adapted to compress
during a slow fuel flow condition, such as when the fuel dispenser
14 is operating in a slow flow mode. The primary spring 124 is adapted
to compress during a high fuel flow condition, such as when the
fuel dispenser 14 is operating in a high flow mode.
The dual poppet valve 120 is illustrated in a partially open mode
in FIG. 11B. As illustrated, the secondary spring 130 has compressed
due to the pressure on the secondary piston 128. Compression of
the secondary spring 130 opens the secondary or bypass fuel path
noted variously by arrows 134. Additionally, the movement of the
secondary piston 128 that compressed the secondary spring 130 causes
the position sensible element 132 to move such that the sensor 98
detects the movement and sends a signal indicative of the movement
to the control system 48 via the sensor communication line 100.
The control system 48 upon receipt of the signal indicating movement
of the position sensible element 132 begins accepting input from
the fuel flow meter 52 and registering the flow of fuel through
the fuel dispenser 14.
The dual poppet valve 120 is illustrated in a fully open mode in
FIG. 11C. When the fuel dispenser 14 is operating in a high flow
mode, the fluid pressure builds up in the dual poppet valve 120
to the point where the primary spring 124 is forced to compress.
This opens the primary fuel path shown variously by arrows 136 and
allows fuel to flow through the fuel dispenser 14 at a high flow
rate. The valve 120 also acts as a check valve to only allow fuel
to flow in one direction thereby preventing backflow which can cause
turbulence and inaccuracies in fuel flow measurement.
The use of the dual poppet valve 120 is also explained with reference
to the flow charts in FIGS. 12A and 12B in the example of a customer
"pre-pay." The process starts (block 300) and the customer
arrives and prepays for fuel at a fuel dispenser 14 (block 302).
The STP is activated, and fuel is pumped to the fuel dispenser 14
(block 304). When fuel flow begins flowing in response to a consumer
inserting the nozzle 20 into the fill neck 22 of the vehicle 12
and initiating fuel flow, fuel flow through the fuel dispenser 14
exerts pressure on the primary piston 122 and the secondary piston
128 (block 306). Next, since the amount of pressure exerted by the
fuel flow is relatively low, only the secondary spring 130 compresses
and the secondary fuel path 134 is opened (block 308). As the secondary
fuel path 134 opens, the position sensible element moves and is
detected by the sensor 98 which reports the movement to the control
system 48 via the sensor communication line 100 (block 310). The
control system 48 begins accepting the pulser signal 54 from the
fuel flow meter 52 (block 312). Fuel is then dispensed at a slow
flow state in the fuel dispenser 14 (block 314). Slow flow rates
range typically between zero and two gallons per minute (gpm) and
preferably approximately 0.25 gpm.
After a small amount of time on the order of five seconds or less,
the fuel dispenser 14 enters into a high flow state. This allows
more fuel to flow through the fuel dispenser 14 to the dual poppet
valve 120. The volume of fuel is now great enough to exert sufficient
pressure on the primary piston 122 to cause the primary spring 124
to compress, thereby opening the primary fuel path 136 (blocks 316
and 318). In due course, the amount of fuel that the fuel dispenser
has dispensed will approach that paid for by the prepayment of block
302 over in FIG. 8B (block 320). As the transaction nears completion,
the fuel dispenser starts to enter a slow flow mode (block 322).
For example, if the consumer paid ten dollars as a prepaid amount
for fuel, the fuel dispenser 14 may start to enter a slow flow state
when the amount of fuel dispensed reaches nine dollars and eighty
cents ($9.80), for example. This slows the amount and volume of
fuel that reaches the dual poppet valve 120 thereby reducing the
pressure against the primary and secondary pistons 122 128. As
the pressure has been reduced on the primary piston 122 the primary
spring 124 decompresses and closes the primary fuel path 136 (block
324). Next, the fuel dispenser 14 enters the slow flow state to
finalize the delivery of fuel to the vehicle 12 to equal the amount
prepaid by the customer (block 326).
The consumer may continue to squeeze the handle on the nozzle 20
as the final ounces of fuel are dispensed into the fuel neck 22
in slow flow state. Once the prepaid amount of fuel has been dispensed,
the fuel dispenser 14 directs fuel flow to stop (block 328). This
stops the flow of fuel to the dual poppet valve 120 thereby reducing
the pressure on the primary and secondary pistons 122 128. With
no pressure on the secondary piston 128 the secondary spring 130
decompresses and closes the secondary fuel path 134 (block 330).
The sensor 98 detects the movement of the position sensible element
132 and informs the control system 48 to ignore pulser signal 54
(block 332). The control system 48 then stops accepting input from
the fuel flow meter 52 via the pulser signal 54 so that erroneous
pulser signals are not counted in the volume and price of fuel dispensed
by the fuel dispenser 14 (block 334) and the process ends (block
336).
Those skilled in the art will recognize improvements and modifications
to the preferred embodiments of the present invention. All such
improvements and modifications are considered within the scope of
the concepts disclosed herein and the claims that follow. |