Power plants – Internal combustion engine with treatment or handling of... – Material from exhaust structure fed to engine intake
Reexamination Certificate
1999-03-22
2001-03-27
Denion, Thomas (Department: 3745)
Power plants
Internal combustion engine with treatment or handling of...
Material from exhaust structure fed to engine intake
C060S280000, C060S298000, C060S605200
Reexamination Certificate
active
06205775
ABSTRACT:
TECHNICAL FIELD
This invention relates generally to an engine and more particularly to a reduction of exhaust emissions.
BACKGROUND ART
The use of fossil fuel as the combustible fuel in engines results in the combustion products of carbon monoxide, carbon dioxide, water vapor, smoke and particulate, unburned hydrocarbons, nitrogen oxides and sulfur oxides. Of these above products carbon dioxide and water vapor are considered normal and unobjectionable. In most applications, governmental imposed regulations are restricting the amount of pollutants being emitted in the exhaust gases.
In the past, NOx emissions have been reduced by reducing the intake manifold temperature, retarding the injection timing, and modifying the injection rate shape. And, the adverse effects on fuel consumption, particulate emissions engine performance have largely been alleviated through improvements in the basic engine design and fuel selection. For example, at the present time smoke and particulates has normally been controlled by design modifications in the combustion chamber and injection pressure, and particulates are normally controlled by traps and filters, and sulfur oxides are normally controlled by the selection of fuels being low in total sulfur. This leaves carbon monoxide, unburned hydrocarbons and nitrogen oxides as the emission constituents of primary concern in the exhaust gas being emitted from the engine.
Many systems have been developed for recycling a portion of the exhaust gas through the engine thereby reducing the emission of these constituents into the atmosphere. The recirculation of a portion of exhaust gas is used to reduce Nox pollution emitted to the atmosphere. In a naturally aspirated engine this process is relative simple. But, with a turbocharged engine, the recirculation of a portion of the exhaust gas into the intake air becomes more complex because the intake pressure may be higher than the exhaust pressure during many operating conditions. In many of such past system a volume of the exhaust gas from the engine was redirected to the intake air of the engine through the turbocharger and/or an aftercooler and to the engine. Such systems caused the premature plugging of aftercooler cores and malfunctioning of the systems. Additionally, with such recirculation system deterioration of the exhaust flow was caused by deposit buildup.
Various approaches have been used to address the adverse pressure gradient issue. For example, throttling valves have been installed in the air inlet, back pressure valves in the exhaust gas, intake manifold venturi tubes, etc. to provide sufficient pressure drop to get the exhaust gas to flow to the intake air. Although this provides the necessary pressure drop to functionally operate an exhaust gas recirculation system several disadvantages, such as, fuel consumption, emissions, and/or performance occur.
The present invention is directed to overcoming one or more of the problems as set forth above.
DISCLOSURE OF THE INVENTION
In one aspect of the invention a system for controlling emissions from an engine is disclosed. The engine defines a plurality of operating parameters, has a rotatable crankshaft (
20
) through which an engine speed can be defined and a plurality of cylinders being defined as a part of the engine. The system for controlling emissions is comprised of an exhaust gas recirculation system. The exhaust gas recirculation system is comprised of a flow of intake air entering a respective one of the plurality cylinders. The intake air is pressurized to a preestablished pressure. A supply of combustible fuel enters the respective one of the plurality of cylinders. A combustion process within the respective one of the plurality of cylinders defines a flow of exhaust gas having a preestablished pressure being less that the preestablished pressure of the intake air during at least a portion of the engine operating parameters. A portion of the exhaust gas is circulated to the intake air and defines a flow of recirculated exhaust gas. The flow of recirculated exhaust gas is cooled prior to being pressurized to a second preestablished level. The pressurization of the flow of recirculated exhaust gas to the second preestablished level is at least equal to the preestablished pressure of the intake air. And, the flow of recirculated exhaust gas is controlled to vary a quantity of recirculated exhaust gas depending on one of the plurality of operating parameters of the engine.
In another aspect of the invention a method of reducing emissions from an engine is disclosed. The engine has a flow of intake air being at a preestablished pressure and a flow of exhaust gas being at a preestablished pressure being less than the preestablished pressure of the intake air. And, a portion of the flow of exhaust gas (
40
) being recirculated into the flow of intake air. The method of reducing exhaust emission is comprised of the following steps: increasing the preestablished pressure of the recirculated portion of the flow of exhaust gas to a second preestablished pressure being at least equal to the preestablished pressure of the intake air; monitoring an operating parameter of the engine; and controlling the recirculated portion of the flow of exhaust gas being recirculated to the intake air depending on the operating parameter of the engine.
REFERENCES:
patent: 3149454 (1964-09-01), Hahn
patent: 3712280 (1973-01-01), Brille et al.
patent: 4048968 (1977-09-01), Aoyama
patent: 4231225 (1980-11-01), Aya
patent: 4702218 (1987-10-01), Yoshioka et al.
patent: 4738110 (1988-04-01), Tateno
patent: 4903488 (1990-02-01), Shibata
patent: 5203311 (1993-04-01), Hitomi et al.
patent: 5205265 (1993-04-01), Kashiyama et al.
patent: 5425239 (1995-06-01), Gobert
patent: 5611203 (1997-03-01), Henderson et al.
patent: 5617726 (1997-04-01), Sheridan et al.
patent: 5771868 (1998-06-01), Khair
patent: 5802846 (1998-09-01), Bailey
patent: 5803027 (1998-09-01), Bell
patent: 5927075 (1999-07-01), Khair
patent: 5937650 (1999-08-01), Arnold
patent: 5974802 (1999-11-01), Blake
patent: 6003315 (1999-12-01), Bailey
patent: 6038860 (2000-03-01), Bailey
patent: 6062026 (2000-05-01), Woollenweber et al.
Coleman Gerald N.
Lawrence Keith E.
Cain Larry G.
Caterpillar Inc.
Denion Thomas
Trieu Thai-Ba
LandOfFree
Exhaust gas recirculation control 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 Exhaust gas recirculation control system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Exhaust gas recirculation control system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2483465