Internal-combustion engines – Charge forming device – Fuel flow regulation between the pump and the charge-forming...
Reexamination Certificate
2000-05-01
2001-07-17
Moulis, Thomas N. (Department: 3747)
Internal-combustion engines
Charge forming device
Fuel flow regulation between the pump and the charge-forming...
C220S721000, C220S723000
Reexamination Certificate
active
06260544
ABSTRACT:
TECHNICAL FIELD
The present invention relates to automotive fuel systems.
BACKGROUND OF THE INVENTION
Automotive fuel systems require a fuel tank, a filler pipe and cap therefor for filling the tank with fuel, a fuel pump and associated fuel lines, and a fuel level sensor. The fuel tank has a rigid tank sidewall usually composed of a metallic or plastic material, wherein the tank sidewall contains the fuel. The filler pipe extends from an opening in the fuel tank to an external opening of the body of the vehicle. The filler cap is removably affixed to the filler pipe, so as to be removed by a driver when fueling the motor vehicle and reaffixed, such as by threading, when fueling is completed. The fuel pump is electrically operated, and is generally designed to deliver a predetermined flow rate of fuel to the engine via a delivery fuel line, and excess fuel is returned to the fuel tank via a return fuel line. Fuel level sensing may be accomplished by any modality known, including float based systems.
Fuel vapor emissions have become increasingly noted a concern which motor vehicle manufacturers must address. One source of fuel vapor emissions concerns tank ventilation, which must be provided so that fuel may be extracted from the fuel tank by the fuel pump, as the volume of fuel taken out by the pump is replaced by atmospheric pressure air. Unfortunately, this same ventilation provision allows escape of fuel vapors. Another fuel vapor emissions problem concerns refueling, whereduring fuel displaces fuel vapor from the tank. To overcome this vapor emissions source, a fuel vapor control system (FVCS) must be included with the fuel system of the vehicle. A typical FVCS includes vapor lines, a carbon canister, a purge solenoid, a vent solenoid, an onboard refueling vapor recovery system, and an onboard diagnostics II (OBD II) pressure sensor.
It would be extremely beneficial if somehow a fuel system could be devised which has fuel vapor emission levels that are very low.
SUMMARY OF THE INVENTION
The present invention is a low fuel vapor emissions fuel system which reduces the need for FVCS and further obviates both the fuel pump and its return fuel line.
The low fuel vapor emissions fuel system includes a rigid tank, a flexible fuel bladder within the tank, a filler pipe connecting between the fuel bladder and an exterior body location, a filler cap which removably seals the filler pipe, a fuel line from the fuel bladder to the engine, an air compression system for selectively pressurizing the cavity between the fuel bladder and the tank, and a fuel level sensor.
In operation, when the ignition key is turned on, the air pump pressurizes the cavity between the interior of the tank and the exterior of the fuel bladder. The pressure is monitored by a pressure transducer which is connected to the vehicle computer. A program of the vehicle computer compares the output from the transducer to the fuel pressure required by the engine and accordingly turns on and off the air pump as needed. An air intake filter is used to prevent contaminants (dirt, water, etc.) from entering the tank through the air pump system. The air pump system also includes an air pressure check valve which is located between the air intake filter and the pressure transducer. The air pressure check valve prevents air from escaping from the tank when the air pump is turned off. The air pump system further includes a vent valve, which also includes an over pressure relief valve. The over pressure relief valve is a safety feature that would open and relieve tank pressure in the event that the tank pressure exceeded a predetermined value.
Fuel is delivered to the engine through the fuel line which is connected to a fuel line attachment on the tank. As the engine uses fuel, the pressure in the tank decreases due to the reduction in volume of fuel in the fuel bladder. The pressure transducer output correspondingly changes, and the program of the vehicle computer turns on the air pump as needed to maintain pressure in the tank. The fuel line attachment includes a shut-off valve which would be open (allowing fuel delivery to the engine) while the engine is cranking or running and closed (prevents fuel from entering the fuel line) while the engine is off.
To add fuel to the tank, the operator would open a filler door. The filler door is interfaced with a sensor switch which is connected to the vehicle computer or directly connected to the air pump system. When the fuel door is opened, a vent valve actuator triggers the vent valve to open, thereby relieving the pressure in the tank. The filler cap is coupled with a cap actuator which prevents filler cap removal from the filler pipe unless fuel pressure in the fuel bladder has dropped to atmospheric pressure. The filler pipe includes a grommet that the fuel station nozzle fits through. The grommet reduces the likelihood of air being drawn into the fuel bladder during filling. Also, the filler pipe is attached to the tank at a location that will allow residual air to escape from the fuel bladder prior to the fuel cap being replaced. The filler pipe further has a filler pipe check valve which selectively prevents pressurized fuel from exiting the fuel bladder. As the fuel bladder is pressurized during vehicle operation, the filler neck check valve is forced closed. The filler pipe check valve has a low reopening pressure which prevents air from entering the fuel bladder when the fuel cap is removed. When fuel is added to the vehicle, the filler pipe check valve will reopen without causing the fuel fill nozzle to shut off prematurely.
There would not be any fuel vapor in the fuel bladder. The only vapor space in the system would be in the filler pipe between the filler pipe check valve and the fuel cap. This vapor volume would be separated from the fuel by the filler pipe check valve. Any leakage of the filler pipe check valve would be a liquid leak into the filler pipe and would be contained by the filler pipe and the fuel cap. FVCS would not be required since there would be no air or fuel vapor inside the fuel bladder that would be displaced during refueling. The air in the tank would be displaced during refueling, but that air would not contain any fuel vapors.
Several benefits of the low fuel vapor emissions fuel system include: lack of fuel vapor emissions to the atmosphere, elimination of an electric fuel pump in contact with fuel, elimination of a fuel sensor submerged in the fuel, elimination of FVCS, redundant fuel containment, and fuel flow unaffected by temperature and battery voltage.
Accordingly, it is an object of the present invention to provide a low fuel vapor emissions fuel system for a motor vehicle.
This, and additional objects, advantages, features and benefits of the present invention will become apparent from the following specification.
REFERENCES:
patent: 3067810 (1962-12-01), Mozic
patent: 3752355 (1973-08-01), Weissenbach
patent: 3887104 (1975-06-01), Cole
patent: 3968896 (1976-07-01), Giacoletti et al.
patent: 4790350 (1988-12-01), Arnold
patent: 5179831 (1993-01-01), Lampe
patent: 5526795 (1996-06-01), Thompson et al.
patent: 5722374 (1998-03-01), Kidokoro et al.
patent: 5868120 (1999-02-01), Van Wetten et al.
patent: 5913451 (1999-06-01), Madison
patent: 5979481 (1999-11-01), Ayresman
Dermanuelian Raffi
Spry Timothy J.
General Motors Corporation
Moulis Thomas N.
Sedlar Jeffrey A
LandOfFree
Low fuel vapor emissions fuel system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Low fuel vapor emissions fuel system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Low fuel vapor emissions fuel system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2566046