Fluid handling – Plural tanks or compartments with parallel flow – With cross connecting passage
Reexamination Certificate
2000-02-04
2001-09-04
Rivell, John (Department: 3753)
Fluid handling
Plural tanks or compartments with parallel flow
With cross connecting passage
C137S565220, C137S565330, C123S509000, C123S514000
Reexamination Certificate
active
06283142
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to fuel delivery systems for automobiles, and more specifically to dual fuel pump delivery systems in bifurcated fuel tanks.
BACKGROUND OF THE INVENTION
The use of bifurcated fuel tanks, also commonly referred to as saddle tanks, in conjunction with fuel delivery systems having a single fuel pump is known. In such systems, a reservoir surrounds the fuel pump and is constantly filled to ensure that a steady supply of fuel is available to the pump at all times. Normally, fuel is drawn into the fuel pump from the bifurcated tank portion housing the fuel pump, but if the fuel level is low or vehicle maneuvering is such that the fuel pump inlet cannot draw fuel, the fuel pump instantly draws fuel from the reservoir. A jet pump is used to draw fuel through a crossover line from the opposing bifurcated portion of the tank and pump the fuel into the reservoir. The reservoir is usually overflowing and excess fuel fills the bifurcated tank portion housing the fuel pump. This insures that if fuel remains in either of the bifurcated tank portions, it is available to the fuel pump.
Today's high-performance and high-power automobiles require a higher rate of fuel flow to the engine than can often be provided with a single fuel pump. It has become necessary to utilize two fuel pumps, operating in parallel, to provide the necessary fuel delivery to the engine. A bifurcated tank presents an appropriate environment for using dual fuel pump delivery systems as one fuel pump can be housed in each of the two bifurcated tank portions. Since the engine demands fuel flow from both fuel pumps, it is important that both tank portions and both fuel pumps have a sufficient amount of fuel. Due to automobile maneuvering (wherein fuel sloshes over the bifurcating wall of the tank), partial tank filling and variations in fuel pump flow capacities, the fuel levels in the bifurcated portions are often unequal.
SUMMARY OF THE INVENTION
The use of bifurcated fuel tanks with two fuel pumps operating in parallel mandates a method of equalizing the fuel levels in each of the bifurcated tank portions. To equalize the fuel levels, fuel must be transferred from one portion of the bifurcated tank to the other portion.
One way to achieve such transfer would be to utilize two jet pumps each having its own dedicated crossover fuel line that transfers fuel over the bifurcating wall. This would be a system similar to that described above for use with single fuel pump delivery systems, only doubled to accommodate the dual fuel pumps. The first crossover fuel line would be connected to the first jet pump and would be dedicated to transferring fuel from the second bifurcated portion to the reservoir in the first bifurcated portion. The second crossover fuel line would be connected to the second jet pump and would be dedicated to transferring fuel from the first bifurcated portion to the reservoir in the second bifurcated portion. Ideally, both jet pumps and crossover lines, working independently of one another, would equalize the fuel level in the bifurcated portions of the tank as the tank empties.
One problem associated with using two individually-dedicated jet pump and crossover line systems to equalize the fuel level in bifurcated tanks is that the jet pumps often have different efficiencies resulting in one bifurcated portion becoming empty before the other. If one jet pump is more efficient than the other, the more efficient jet pump empties its respective bifurcated portion faster than the less efficient jet pump can supply fuel from its respective bifurcated portion. As such, the less efficient jet pump cannot equalize the fuel level between the bifurcated portions. If one bifurcated portion empties first, and the respective fuel pump lacks a sufficient fuel supply, fuel flow interruptions will occur, creating increased HC and NOX emissions and putting the engine and catalytic converter reliability at risk. In addition to potentially damaging the engine, there is a good chance that the fuel pump, which continues to run without pumping any fuel, will be damaged.
The present invention alleviates these problems by incorporating a single crossover fuel line that communicates with both jet pumps. Two shuttle valves control the direction of fuel flow through the single crossover line to maintain substantially equal fuel levels in both bifurcated portions until the tank is empty. Should one bifurcated portion empty before the other, both jet pumps draw fuel from the bifurcated portion with the remaining fuel, thereby insuring that both fuel pumps continue to provide fuel to the engine until both bifurcated portions are substantially empty. Unlike using two individually-dedicated jet pumps and crossover lines, fuel is only transferred when necessary, as opposed to constantly pumping fuel out of and into both tank portions.
Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims, and drawings.
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Fischerkeller Rolf
Wheeler Tony Joe
Wickett Paul
Michael & Best & Friedrich LLP
Rivell John
Robert Bosch Corporation
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