Power plants – Fluid motor means driven by waste heat or by exhaust energy... – With supercharging means for engine
Reexamination Certificate
2000-03-27
2001-12-04
Nguyen, Hoang (Department: 3748)
Power plants
Fluid motor means driven by waste heat or by exhaust energy...
With supercharging means for engine
C060S612000, C060S616000
Reexamination Certificate
active
06324846
ABSTRACT:
TECHNICAL FIELD
This invention relates generally to an exhaust gas recirculation system for use with an internal combustion engine and more particularly to the exhaust gas recirculation system having a generator operatively connected to a turbocharger.
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, NO
x
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 have normally been controlled by design modifications in the combustion chamber, 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 NO
x
pollution emitted to atmosphere. In a naturally aspirated engine this process is relatively simple. But, with a turbocharged, 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 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.
Prior turbocompounding systems typically use two turbines in series to raise the exhaust manifold pressure above the intake air. However, turbocompounded engines operating at low engine speeds operate inefficiently due to the decrease in the pressure ratio across the turbines in series. Prior techniques have coupled the compounded turbochargers to the engine using mechanical, hydraulic, and flexible couplings. Mechanical couplings need to be extremely strong to withstand the inertia of the turbine, thus adding cost to the coupling. Hydraulic couplings may be used but add complication to the system and additional losses of efficiency during engine operation. Flexible elements may also be used but may have a resonance problem due to the overlapping of frequencies of the flexible coupling the engine.
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. In particular, exhaust gas systems which utilize a turbocharger have several performance disadvantages, such as balancing between the turbocharger compressor and turbine portions and turbine operating efficiencies.
The present invention is directed to overcoming one or more of the problem as set forth above.
DISCLOSURE OF THE INVENTION
In one aspect of the invention an exhaust gas recirculation system for use with an internal combustion engine comprises an intake manifold, an exhaust manifold, a heat exchanger, a first turbocharger, and a generator. The heat exchanger defines a donor portion which has an inlet end that is in fluid communication with the exhaust manifold and an outlet end which is in fluid communication with the intake manifold. A recipient portion of the heat exchanger has an inlet end and an outlet end. The first turbocharger defines a turbine section which has an inlet portion that is in fluid communication with the exhaust manifold and an outlet portion. A compressor section has an inlet portion and an outlet portion that is in fluid communication with the inlet end of the recipient portion of the heat exchanger and the intake manifold. The turbine section is drivingly connected to the compressor section. The generator is operatively connected to the first turbine section of the turbocharger.
In another aspect of the present invention an exhaust gas recirculation system for use with an internal combustion engine comprises an intake manifold, an exhaust manifold, a heat exchanger, a first turbocharger, and a generator. The heat exchanger defines a donor portion which has an inlet end that is in fluid communication with the exhaust manifold and an outlet end that is in fluid communication with the intake manifold. The inlet end of the donor portion has a first control member disposed therein. A recipient portion has an inlet end and an outlet end and the inlet end of the recipient portion has a second control member disposed therein. The first turbocharger defines a turbine section which has an inlet portion which is in fluid communication with the exhaust manifold and an outlet portion. A compressor section has an inlet portion and an outlet portion which is in fluid communication with the inlet end of the recipient portion of the heat exchanger and the intake manifold. The turbine section is drivingly connected to the compressor section. The generator is operatively connected to the first turbine section of the turbocharger.
REFERENCES:
patent: 2848866 (1958-08-01), Geislinger
patent: 3141293 (1964-07-01), Crooks
patent: 5105624 (1992-04-01), Kawamura
patent: 6112523 (2000-09-01), Kamo et al.
Cain Larry G.
Caterpillar Inc.
Golden James B.
Nguyen Hoang
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