Power plants – Internal combustion engine with treatment or handling of... – By means producing a chemical reaction of a component of the...
Reexamination Certificate
1999-08-16
2001-09-25
Denion, Thomas (Department: 3748)
Power plants
Internal combustion engine with treatment or handling of...
By means producing a chemical reaction of a component of the...
C060S307000, C417S038000
Reexamination Certificate
active
06293097
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to exhaust systems for motor vehicles and, more specifically, to an on-board reductant delivery system for an exhaust system of a motor vehicle.
2. Description of the Related Art
Exhaust systems for motor vehicles are known. Typically, the exhaust system includes an exhaust manifold connected to an engine of the motor vehicle and a close coupled catalyst connected via an exhaust pipe to the exhaust manifold. The exhaust system also includes an underbody catalyst connected via the exhaust pipe to the close coupled catalyst and a tail pipe connected to the underbody catalyst.
Lean NOx catalysts (LNC) and selective catalytic reduction catalysts (SCR) are known to reduce NOx emissions from diesel and lean-burn gasoline engines. In order to promote NOx reduction under oxidizing environments, certain reductants such as hydrocarbon (HC) fuels and/or urea solution or other ammonia (NH3) containing compounds must be added. To function effectively, the conditions for adding these reducing compounds to the exhaust system are critical. Specifically, the injected quantity must precisely match the NOx concentration in order to obtain maximum conversion and to avoid HC and/or NH3 slippage. Also, the response time must be fast to deal with the sudden increase of NOx during acceleration. Further, the fluid droplet size must be very fine and well distributed across catalyst surfaces to achieve high NOx conversion efficiencies. In addition, the system must be compact, light-weight, cost and energy efficient.
One known reductant delivery system uses a solenoid valve to meter diesel fuel, which was then dripped into the exhaust pipe. Another known reductant delivery system includes an injection system using a large fuel pump with a pressure regulator, a return line and an injector to meter and inject fuel into the exhaust. Yet another known reductant delivery system used a fuel pump, a fuel injector and an air assisted spray system. However, these systems are either slow, less effective in fluid dispersion, cumbersome, heavy, costly, noisy or high energy consumption.
Although the above reductant delivery systems have worked, it is desirable to improve NOx conversion efficiencies of selected catalysts under oxidizing conditions by delivering precise amount of reductants with fast response time and good distribution. It is also desirable to provide a low cost, robust reductant delivery system to control NOx emissions of vehicles equipped with lean NOx catalyst and/or selective catalytic reduction catalysts. It is further desirable to provide a compact, lightweight, energy efficient and potentially durable reductant delivery system for on-board vehicle application. Therefore, there is a need in the art to provide an on-board reductant delivery system for a motor vehicle.
SUMMARY OF THE INVENTION
Accordingly, the present invention is an on-board reductant delivery system for a motor vehicle. The on-board reductant delivery system includes a mixer
ozzle system for connection to an exhaust system of a motor vehicle. The on-board reductant delivery system also includes a fluid metering system connected to the mixer
ozzle system for metering reductants to the mixer
ozzle system. The on-board reductant delivery system further includes an air supply system connected to the mixer
ozzle system for delivering pressurized air to the mixer
ozzle system. The mixer
ozzle system mixes the reductants and pressurized air and sprays the mixture in the exhaust system of the motor vehicle to reduce NOx.
One advantage of the present invention is that an on-board reductant delivery system is provided for a motor vehicle. Another advantage of the present invention is that the on-board reductant delivery system is compact and efficient to disperse controlled quantity of reductants for vehicles equipped with active lean NOx catalysts and/or selective catalytic conversion catalysts. Yet another advantage of the present invention is that the on-board reductant delivery system improves NOx conversion efficiencies of selected catalysts under oxidizing conditions by delivering precise amount of reductants with fast response time and good distribution. Still another advantage of the present invention is that the on-board reductant delivery system is compact, lightweight, energy efficient, low-cost, quiet and potentially durable for on-board vehicle application. A further advantage of the present invention is that the on-board reductant delivery system is able to maintain constant pressure drop across nozzle to assure good atomization.
Other features and advantages of the present invention will be readily appreciated, as the same becomes better understood after reading the subsequent description taken in conjunction with the accompanying drawings.
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Hammerle Robert Henry
Wu Ching-Hsong
Denion Thomas
Ford Global Technologies Inc.
Porcari Damian
Trieu Thai-Ba
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