Fluid handling – Processes
Reexamination Certificate
2001-06-28
2002-12-17
Chambers, A. Michael (Department: 3753)
Fluid handling
Processes
C137S565160, C137S565300, C137S396000, C123S514000, C417S040000
Reexamination Certificate
active
06494226
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to fuel transfer from a plurality of fuel tanks to the engine of a vehicle, and more particularly, to a method and apparatus for maintaining substantially equivalent fuel levels within the plurality of fuel tanks.
2. Description of the Related Art
Vehicles such as, for example, heavy and medium duty trucks many times employ a dual fuel tank configuration providing a large fuel capacity. A fuel pump is utilized to draw fuel from the fuel tanks to the vehicle engine.
As is known in the art of internal combustion powered vehicles, fuel pumps remove more fuel from fuel tanks than is utilized in the engine so as to cool the fuel injector pump while supplying sufficient pressure to the fuel injectors. The surplus fuel which is not used by the engine is constantly returned to the fuel tank. In the dual tank configurations currently utilized, fuel is drawn from and returned to both fuel tanks simultaneously. These systems do not draw fuel evenly from both tanks nor do they return fuel evenly to both tanks. Uneven fuel draw and return can be attributed to many factors affecting fluid flow, including pressure differentials and physical attributes of the fluid distribution system including, but not limited to partial blockage of distribution piping. Spillage may occur if fuel is drawn primarily from one of the two tanks and fuel is returned primarily to the other of the two tanks.
Roads and parking areas are generally formed with a crowned configuration leading to one of the two fuel tanks being lower relative to the other. Fuel is more easily drawn from the higher tank and consequently the lower tank has less fuel drawn from it. This can exacerbate the problem of uneven fuel draw and the consequent spillage which can occur.
Uneven fuel draw and return additionally causes balance problems when one of the two fuel tanks contains significantly more fuel than the other. Hydrocarbon fuel typically weighs approximately 6 lbs. per gallon and the fuel tanks in question generally have a capacity of approximately 100 gallons. The substantial weight differential caused by an uneven amount of fuel in the two tanks can cause maintenance and other problems for the vehicle operator including, for example, uneven tire wear. An additional problem associated with the dual tank configuration occurs when one of the two tanks is emptied and air is drawn into the engine from the fuel supply line connected to the empty tank. When air is drawn into the engine, engine stall is experienced and restarting the engine is problematic.
Many vehicles utilize an engine driven fuel pump to transfer fuel from the fuel tank to the engine. As is known in the art, the output of an engine driven fuel pump is a linear function of its speed. Therefore, during engine crank, when engine speed is very low, engine driven fuel pumps create only a small amount of lift and, consequently, relatively small flow. With this in mind, engine driven fuel pumps are slow to prime. A discrete priming pump would allow for faster priming of an engine driven fuel pump. A priming pump will be particularly advantageous, for example, if the engine has run out of fuel, the fuel supply line is completely emptied by drain back occurring when the engine is not running, or a filter change has been effected. For example, during fuel filter change, the new fuel filter must be filled with fuel to complete the fuel filter change and a priming pump may be utilized to provide fuel to the newly installed fuel filter and to prime the engine driven fuel pump.
Modern vehicles conventionally utilize computer control systems to monitor and control various vehicle systems. Vehicle computer control systems typically utilize three stages: input, processing, and output. The input stage of a vehicle control system receives input from various sensors placed throughout the vehicle to monitor vehicle conditions. The processing stage of a computer control system compares the various inputs to the acceptable operational parameters stored within the memory of the computer control system. Finally, the output from a vehicle's control system signals changes in vehicle operation to bring the input parameters within the desired ranges or values. A typical vehicle control system, or electronic control module (ECM) includes various inputs and outputs. Various sensors throughout the vehicle monitor the operational parameters of the vehicle and transmit these operational parameters to the ECM, e.g., in the form of an electrical signal. Generally, the three main functions of the ECM, i.e., input, processing, and output, are performed by various sections of the ECM. For example, the input stage of the ECM is performed by an input section operable to convert signals from the various vehicle sensors into a form the ECM can effectively utilize. The processing section of the ECM generally includes a memory section having data stores indicating acceptable and/or optimum operational parameters. The processing section of the ECM generally also includes a logic section for performing necessary arithmetic calculations including comparisons of sensor inputs to acceptable parameters stored in the memory section. Furthermore, the arithmetic calculations of the logic section may be utilized to convert sensor signals into alternative forms. For example, the input to the ECM from an engine speed sensor (for example, sensing rotations of the various parts of the car's transmission) can be transformed via the logic section of the ECM into a measure of vehicle speed which can then be output via the ECM output section to, e.g., the vehicle speedometer. Furthermore, many vehicles utilize additional microprocessors placed throughout the vehicle to control various vehicle functions.
What is needed in the art is an apparatus for effectively providing fuel from a dual fuel tank configuration to an engine while maintaining a substantially equivalent volume of fuel in each of the fuel tanks.
What is further needed in the art is an apparatus for maintaining a substantially equivalent volume of fuel in a plurality of fuel tanks, which apparatus may be configured to include an integral controller or which may utilize the existing vehicle ECM.
What is further needed in the art is an apparatus which advantageously combines a device for maintaining a substantially equivalent level of fuel in a dual fuel tank configuration while also providing a priming pump for the engine mounted fuel pump of a vehicle.
SUMMARY OF THE INVENTION
The present invention is directed to improve upon the aforementioned fuel storage and distribution systems for vehicles having more than one fuel tank, wherein it is desired to utilize a dual fuel tank configuration in which the fuel levels in both fuel tanks remain substantially equal. The present invention provides an electric transfer pump configured to be in fluid communication with both fuel tanks. Fluid level sensors measure the fluid level in both fuel tanks and are communicatively connected to the electric transfer pump via a microprocessor. When the fluid level in one of the tanks reaches a predetermined lower level than in the other tank, the microprocessor signals the electric transfer pump to distribute fuel from the tank having the greater fuel volume to the other tank.
The microprocessor utilized in accordance with the present invention may be a stand-alone microprocessor mounted externally of the electric transfer pump, may be incorporated into the pump itself, or may comprise the vehicle ECM. Utilizing the existing vehicle ECM can be beneficial from a cost standpoint, since modern vehicles are conventionally equipped with an ECM and, therefore, an additional microprocessor is not required. However, installations utilizing a stand-alone microprocessor, or a microprocessor incorporated into the electric transfer pump may be advantageous in a retrofit situation, or in a vehicle having an ECM without an available input, or without the additional memory required to operate the electric trans
Harvey Richard W.
Tipton Larry J.
Baker & Daniels
Chambers A. Michael
Federal-Mogul World-Wide, Inc.
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