Patent Application
20050242110
1. Field of the Invention
This invention relates to fuel dispensing systems and more particularly relates to a programmable fuel dispensing system.
2. Background Information
Presently fuel dispensing systems at gas stations and other locales require a complex installation of circuits, relays, and contactors to control fuel dispensing plants. These electronic components are typically mounted in a separate control room on a wall. The relays, contactors, and circuits are to this day usually installed and mounted by an electrician often, in fact usually, without the benefit of an overall wiring diagram.
The sheer number of input and control relays result in a complex installation. Also while these contactors and relays are much more reliable than in the past, so many are required that servicing and repairs are required more frequently than is desirable. Further the lack of a reliable wiring diagram exacerbate the problems. So much so that the removal of relays and moving contactors would be advantageous.
It is therefore one object of the present invention to simplify the installation of a fuel dispensing system.
Another object of the present invention is to simplify a fuel dispensing system by reducing the number of relays or moving contactors in a system.
Yet another object of the present invention is to simplify a fuel dispensing system by eliminating substantially all relays and moving contactors in the system.
Still another object of the present invention is to simplify a fuel dispensing system by replacing relays and moving contactors with extremely reliable solid state devices.
Yet another object of the present invention is to simplify a fuel dispensing system by replacing relays, contactors, and control circuits with a solid state programmable logic controller.
Still another object of the present invention is to improve the reliability and simplify a fuel dispensing system by replacing relays, contactors, and control circuits with a programmable solid state logic controller that is programmable remotely.
Yet another object of the present invention is to improve the reliability and simplify a fuel dispensing system by replacing relays, contactors, and control circuits with a programmable solid state logic controller that is remotely programmable by use of a modem.
Still another object of the present invention is to provide a more efficient fuel dispensing system by replacing relays, contactors, and control circuits with a programmable logic controller that is programmable remotely through a modem that also includes control of other circuits at the fuel dispensing station.
Yet another object of the present invention is to improve the reliability and simplify fuel dispensing systems by replacing relays, contactors, and central circuits with a remotely programmable solid state logic controller that can also control station lighting.
Still another object of the present invention is to provide a more reliable fuel dispensing system by replacing relays, contactors, and central circuits with a remotely programmable solid state logic controller that can also monitor fuel tanks at a station.
The purpose of the present invention is to simplify and increase the reliability of fuel dispensing system by replacing relays, contactors, and central circuits with solid state devices such as a programmable logic controller (PLC) that also improves maintenance and simplifies the installation.
The fuel dispensing system of the present invention can be installed at a service station, mini-mart, or fuel depot. Typically, the system is installed in a secured, lockable equipment room out of sight of the public, but may also be in public areas as it is secured. The fuel dispensing system replaces an assortment of panel-boards, relays, contactors, and central circuits of present fuel dispensing systems installed by electricians without the benefit of a wiring diagram. Service calls are not only reduced but are also simplified by the present invention.
The system employs a solid state programmable logic controller (PLC) to replace many of the relays, contactors, and central circuits of a fuel dispensing system. Specifically, input and central relay logic are eliminated leaving only contactors to turn off fuel dispensers or pumps except where a system lockout relay shuts the system down in case of malfunctions in fuel tanks or tank containers. All power distribution components, panel boards, contactors, etc. are combined in one cabinet with all connections terminated on terminal blocks. The replacement of relays and contactors with a solid state programmable logic controller is fully compatible with existing fuel dispensing control systems and requires less space presenting a much neater appearance.
The programmable logic controller is preferably an Allen Bradley Model 1762L40AWA or its equivalent. Logic inputs turn on a logic output which turns on a selected fuel pump usually through a single relay to pump fuel. Removal of a logic input stops fuel pumping by turning off the pump relay.
The system also monitors fuel tanks or fuel containment tanks. Typically a leak in a fuel tank or fuel containment tank will result in an input to the logic circuit that prevents any outputs to stop fuel dispensers from being operated until the problem has been located and repaired. This leak may be fuel leaking from the tank or water leaking into the tank. This optional feature is unique to the fuel dispensing system of the invention. Once the problem is resolved, the system can be reset and put back in service to continue normal operation.
The programmable logic controller can also be used to control other features at a pumping station such as lighting and signs. Outputs from either a photocell or a time switch to the programmable logic controller will control the station lighting and signs on and off times.
The novel fluid dispensing system of the present invention simplifies and improves the reliability of fuel dispensing particularly at self-service stations. It is comprised of a central control panel produced, debugged, and optimized at a factory location, then installed in the field and connected to existing station equipment. This method greatly simplifies the task of field installation when compared to the conventional practice of building a relay logic design on site with or without design drawings and assembly sketches that are difficult at best to implement and then try to make it work. The overall design is similar to embedded computer control systems that use a central processor interfaced to local inputs and outputs.
The “brains” of the system is a modem programmable logic controller (PLC) or microprocessor that is programmable externally and monitored via a modem over any available communications link. This arrangement provides an opportunity for third party oversight and control of self-service gas station complexes and fuel depots as a service but can also serve the owner/operator. The PLC replaces a plurality of relays with solid state reliability. While electromechanical relays have a very long average life expectancy solid state logic has no known wearout mechanism such as electromechanical relay contact wear and can be expected to operate reliably for many years. Use of many electromechanical relays almost assures that some will fail well before their maximum life expectancy.
The PLC is programmed to essentially automate the operation of a self-service gas station. It enables the fuel dispensing pumps upon validation, it turns on the station lights and signs at dusk, it monitors the safe condition of the fuel storage tanks. It accepts program changes from remote input via modem and reports operating conditions for off-site monitoring and control. In a current embodiment of the invention, the PLC function is implemented by a commercially produced industrial controller such as a Allen Bradley Model 1762L40 AWA, a GE/Fanuc UAA007 or their equivalent mounted in a compact wall mounted enclosure and connected to an array of interface contactors, relays and terminal strips that facilitate rapid and accurate connection to existing station equipment. Support equipment for the controller such as battery back-up and power conditioning is also provided.
The above and other objects, advantages, and novel features of the invention will be more fully understood from the following detailed description and the accompanying drawings, in which:
A schematic block diagram of the programmable solid state fuel dispensing control system according to the invention is illustrated. The system includes a fuel station electronically enhanced control panels. It is an advancement over the electro-mechanical style of equipment typically implemented in conventional present day fuel dispensing systems. The new re-designed system eliminates the all “hard contact” style of numerous relays used to interface with the fueling system, lighting control system, and cash registers.
Referring to the schematic block diagram of
The typical installation and arrangement illustrated in
PLC 10 is programmed to operate various components of existing fuel station equipment by engaging interface relays or contactors 15 that have current ratings sufficient for the various loads. The sequence of relay and contactor operations is determined by PLC 10 programming in response to inputs from a variety of sensors 51, 53, 55 and contact closures 15 throughout the station.
For example when dispenser 40 is activated by a customer lifting a dispensing nozzle from its cradle and choosing a grade of fuel (e.g., premium), contact closure 15 sends a signal to PLC 10 to turn on pump 57 connected to premium tank 54. Pumping will proceed unless fault detecting tank sensor 55 has not sent a signal indicating there is a fault condition. If a leak, either water leaking into the tank or fuel leaking out, has previously occurred in premium tank 54, fault detecting sensor 55 sends a signal that causes PLC 10 to prohibit dispensing of fuel from premium tank 54. This will only impede dispensing premium grade fuel from premium tank 54 but will not interfere with the availability or dispensing of other grades of fuel from other tanks 50 and 52 which will keep the functioning parts of the station in operation. Further once the problem has been corrected (i.e., leak repaired) fault detecting sensor 55 will be reset bringing premium grade tank 54 back on line.
PLC 10 also performs a number of housekeeping chores in addition to monitoring, reporting, and operating fuel dispensing equipment. These chores are performed by connecting station canopy lights 60, 62, and 64 and perhaps sign lights 68 to PLC 10 through interface contactors 15 programmed to control these functions. PLC 10 will receive signals from either a photo sensor 70 and/or a timer 75. Sensor 70 would provide an input to PLC 10 at dusk to operate station canopy lights 60, 62, and 64 and perhaps sign lights 68.
Alternately timer 75 could be used alone or in conjunction with photo sensor 70 to control lights at a specific time. For example timer 75 could turn all lights on at a specific time while photo sensor 70 would turn them off at sunrise or vice versa. To preserve the integrity of the local clock and PLC 10 program backup battery 20 is provided that has sufficient capacity to ride out even extended power failures.
Thus there has been disclosed a novel and unique programmable solid state fuel dispensing system that can be used not only in gas stations but also in a wide variety of industrial processing plants. The system can be tailored to monitor, control and report on performance by an appropriately configured program.
This invention is not to be limited by the embodiment shown in the drawings and described in the description which is given by way of example and not of limitation, but only in accordance with the scope of the appended claims.
