Power plants – Fluid motor means driven by waste heat or by exhaust energy... – With supercharging means for engine
Reexamination Certificate
2000-11-03
2001-11-27
Nguyen, Hoang (Department: 3748)
Power plants
Fluid motor means driven by waste heat or by exhaust energy...
With supercharging means for engine
C060S605100
Reexamination Certificate
active
06321537
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an exhaust gas recirculation system for use in an internal combustion engine, and, more particularly, to an exhaust gas recirculation system for use in an internal combustion engine having multiple turbochargers.
BACKGROUND ART
An internal combustion engine may include one or more turbochargers for compressing a fluid which is supplied to one or more combustion chambers within corresponding combustion cylinders. Each turbocharger typically includes a turbine driven by exhaust gases of the engine and a compressor which is driven by the turbine. The compressor receives the fluid to be compressed and supplies the compressed fluid to the combustion chambers. The fluid which is compressed by the compressor may be in the form of combustion air or a fuel and air mixture.
It is known to provide multiple turbochargers within a turbocharger system in an internal combustion engine. For example, U.S. Pat. No. 3,250,068 (Vulliamy) discloses an internal combustion engine having two turbochargers. A first turbocharger includes a turbine which is driven by a single exhaust manifold on the internal combustion engine. The spent exhaust gas from the turbine of the first turbocharger is transported in a series manner to the inlet of a turbine of the second turbocharger. The spent exhaust gas is then discharged to the ambient environment from the turbine of the second turbocharger. The compressor of the second turbocharger compresses ambient combustion air and provides the compressed combustion air in a series manner to the compressor of the first turbocharger, which in turn transports the compressed combustion air to the intake manifold of the engine.
An exhaust gas recirculation (EGR) system is used for controlling the generation of undesirable pollutant gases and particulate matter in the operation of internal combustion engines. Such systems have proven particularly useful in internal combustion engines used in motor vehicles such as passenger cars, light duty trucks, and other on-road motor equipment. EGR systems primarily recirculate the exhaust gas by-products into the intake air supply of the internal combustion engine. The exhaust gas which is reintroduced to the engine cylinder reduces the concentration of oxygen therein, which in turn lowers the maximum combustion temperature within the cylinder and slows the chemical reaction of the combustion process, decreasing the formation of nitrous oxides (NOx). Furthermore, the exhaust gases typically contain unburned hydrocarbons which are burned on reintroduction into the engine cylinder, which further reduces the emission of exhaust gas by-products which would be emitted as undesirable pollutants from the internal combustion engine.
With an EGR system as described above, it is known to control the amount of exhaust gas which is mixed with the combustion air for introduction into the intake manifold. Typically, a mixer such as a venturi-type mixer or the like is utilized to control the amount of exhaust gas which mixes with the combustion air. However, controlling the amount of exhaust gas which mixes with the combustion air using only a mixer may not be sufficient to provide fine adjustments to the combustion air to exhaust gas mixture ratio.
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, an internal combustion engine is provided with a plurality of combustion cylinders, at least one exhaust manifold, and at least one intake manifold. Each exhaust manifold is coupled with a plurality of the combustion cylinders, and each intake manifold is coupled with a plurality of combustion cylinders. A first turbocharger includes a first turbine having at least one inlet and an outlet, and a first compressor having an inlet and an outlet. The at least one first turbine inlet is fluidly coupled with a corresponding exhaust manifold. A second turbocharger includes a second turbine having at least one inlet and an outlet, and a second compressor having an inlet and an outlet. The at least one second turbine inlet is fluidly coupled with a corresponding exhaust manifold. A valve assembly includes an inlet, a first outlet and a second outlet. The valve inlet is fluidly coupled with a corresponding first turbine inlet, the valve first outlet is fluidly coupled with the second turbine inlet, and the valve second outlet is fluidly coupled with at least one intake manifold.
In another aspect of the invention, a method of recirculating exhaust gas in an exhaust gas recirculation system of an internal combustion engine is provided with the steps of: providing a first turbocharger including a first turbine having at least one inlet and an outlet, and a first compressor having an inlet and an outlet, the at least one first turbine inlet fluidly coupled with a corresponding exhaust manifold; providing a second turbocharger including a second turbine having at least one inlet and an outlet, and a second compressor having an inlet and an outlet, the at least one second turbine inlet fluidly coupled with a corresponding exhaust manifold; providing a valve assembly including an inlet, a first outlet, a first valve associated with the first outlet, a second outlet and a second valve associated with the second outlet, the valve inlet fluidly coupled with a corresponding exhaust manifold and the first turbine inlet, the valve first outlet fluidly coupled with the second turbine inlet, and the valve second outlet fluidly coupled with at least one intake manifold; and selectively opening and closing the valve first outlet and the valve second outlet.
REFERENCES:
patent: 5197287 (1993-03-01), Okimoto et al.
patent: 5207063 (1993-05-01), Blake
patent: 5277029 (1994-01-01), Kidokoro et al.
Coleman Gerald N.
Faletti James J.
Feucht Dennis D.
Pierpont David A.
Caterpillar Inc.
Nguyen Hoang
Taylor Todd T.
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