Fluid handling – Line condition change responsive valves – Direct response valves
Reexamination Certificate
2001-12-20
2004-08-31
Lee, Kevin (Department: 3753)
Fluid handling
Line condition change responsive valves
Direct response valves
C137S527000, C251S298000
Reexamination Certificate
active
06782916
ABSTRACT:
FIELD OF THE INVENTION
The invention relates generally to fuel systems for work vehicles. More particularly, it relates to check valves in such fuel systems to control the flow of fuel between a plurality of tanks.
BACKGROUND OF THE INVENTION
Many work vehicles such as tractors, combines, graders, backhoes and the like are made to operate on uneven ground. In addition, these vehicles often have a plurality of fuel tanks that are coupled together to provide fuel from more than one source to the engine of the vehicle.
In one common arrangement, fuel tanks are located on opposing sides of the vehicle rather than in a front and rear arrangement. One of the problems with this arrangement, especially when the fuel tanks are coupled by a cross feed line that permits fluid to flow freely between them, is that all the fuel flows to the lower of the two tanks away from the fuel suction line that carries fuel to the engine. When the fuel suction line is not immersed in fuel, no fuel gets to the engine, and the vehicle's engine dies because of fuel starvation.
When the work vehicle travels along the side of a field, it tilts to one side or the other. When the fuel tanks are arranged with one tank on one side of the vehicle and the other tank on the other side, this tilted orientation causes the fuel tank on the uphill side of the work vehicle to be elevated above that of the fuel tank on the downhill side of the work vehicle. This can raise one tank above the other by as much as 1 or 2 feet.
In many work vehicles, a cross feed line is provided between the two tanks and a fuel pickup or suction line is disposed in one tank. A fuel pump sucks fuel from the tanks through this open-ended suction line and sends it to the engine of the work vehicle. The cross feed line is typically coupled to the fuel tanks at the bottom of the fuel tanks to permit fuel to flow from side to side and from tank to tank as the fuel is consumed to keep the level of fuel in each tank the same.
When the vehicle tilts, however, and the fuel level is low, one tank and a portion of the cross feed line is elevated with respect to the other tank. As a result, gravity causes fuel to flow to the low tank. If the angle of tilt is sufficiently great, this forms a puddle of fuel, as much as several gallons, in the low tank.
This causes the fuel suction line to lose liquid suction and suck only vapor instead of the liquid fuel itself. When this happens, fuel pressure drops and the engine is starved for fuel.
If the operator immediately returns to level ground, the level of the tanks is equalized and the remaining fuel again submerges the fuel suction line in the one tank. Fuel flow is restored to the engine and the vehicle continues operating. On the other hand, if the work vehicle travels an extended distance in this tilted position, the engine, starved for fuel, will die and the vehicle can become stranded in spite of the fact that there are several gallons of fuel left in the low tank.
Work vehicles such as tractors often cultivate fields that are often disposed at an angle. For this reason, fuel starvation is a particular problem for tractors and other cultivating equipment. Typically, however, tractors and similar field cultivating vehicles periodically reverse directions and retrace their paths as they travel back and forth from headland to headland through a field. When they reverse directions and proceed back in the opposite direction along the same slope, the low tank becomes the high tank and the high tank becomes the low tank. As a result, fuel that previously pooled in the low tank flows through the cross feed line and pools in the erstwhile high tank. This periodic reversal of direction and consequent reversal of vehicle angle insures that the small amount of fuel remaining in the fuel system moves back and forth every few minutes from tank to tank. This mode of operation can be used to insure that fuel is always available to the engine if fuel that pools around the fuel suction line is prevented from flowing back away from the suction line.
What is needed, therefore, is an apparatus for regulating the gravitational flow of fuel through a cross feed line coupling to fuel tanks that are laterally disposed in a work vehicle. What is also needed is a method of preventing fuel from flowing from a high tank to a low tank when a work vehicle with two laterally disposed fuel tanks is driven across a slope. What is also needed is an apparatus for a fuel system that will prevent gravitational forces from acting on the fuel level in those tanks from moving the fuel through a cross feed line to a tank that is disposed below a fuel suction line thereby starving the fuel suction line for fuel.
It is an object of this invention to provide such an apparatus as part of a fuel system for a work vehicle.
SUMMARY OF THE INVENTION
In accordance with the first embodiment of the invention a fuel tank system for work vehicles is provided that includes a first fuel tank having a first fuel outlet disposed on the lower portion thereof, a second fuel tank having a second fuel outlet disposed on the lower portion thereof, a cross feed line having an inner diameter and coupled to and between the first and second outlets, and a check valve disposed in the cross feed line to block fuel from flowing through the cross feed line from the second tank to the first tank. The check valve may include an annulus having an outer diameter and defining a circular opening, and a valve element pivotally coupled to the annulus and sized to seal against and block the circular opening in a first pivotal position and to open the circular opening in a second pivotal position. The annulus may define a generally circular sealing surface disposed about a circumference thereof and the valve element may define a generally circular sealing surface disposed about the periphery thereof and configured to abut and seal against the generally circular sealing surface of the annulus. The fuel tank system may further include a clamp extending around the outer periphery of the cross feed line and disposed to compress the cross feed line against the annulus. The valve element may include a substantially planar and circular polymeric sheet having an upper portion, a lower portion, and a polymeric hinge portion formed integral with and coupling the upper and lower portions. The valve element may also include at least one planar stiffener sheet fixed to the lower portion of the circular polymeric sheet. The stiffener sheet may be substantially coplanar with the lower portion and may be fixed to one side of the lower portion. The upper portion of the annulus may have a radial thickness greater than a lower portion of the annulus, wherein the greater thickness is sufficient to anchor the upper portion of the circular polymeric sheet to the annulus. The upper portion of the circular polymeric sheet may be coupled to the upper portion of the annulus by at least one fastener. The valve element may be disposed to open in response to pressure provided by the weight of fuel by the first tank acting against the valve element and further wherein the valve element may be disposed to close in response to the weight of fuel from the second tank acting against the valve element.
In accordance with the second embodiment of the invention a flapper valve for fuel tank system is disclosed that includes a polymeric annulus having a width in an axial direction greater than its thickness in a radial direction, and a generally planar valve element including an upper portion fixed to the annulus and a lower portion configured to pivot in respect to the annulus, thereby providing a fluid passageway between the annulus and the valve element. The valve element may include a substantially planar and circular polymeric sheet having an upper portion, a lower portion, and a polymeric hinge portion formed integral with and coupling the upper and lower portions. The valve element may also include at least one planar stiffener sheet fixed to the lower portion of the circular polymeric sheet. The stiffener sh
Daniels Kenneth
Svendsen Darrel J.
Case Corporation
Lee Kevin
Stader John William
Webb Collin A.
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