Power plants – Fluid motor means driven by waste heat or by exhaust energy... – With supercharging means for engine
Reexamination Certificate
1999-08-31
2001-03-27
Koczo, Michael (Department: 3748)
Power plants
Fluid motor means driven by waste heat or by exhaust energy...
With supercharging means for engine
Reexamination Certificate
active
06205787
ABSTRACT:
TECHNICAL FIELD
This invention is directed to methods and apparatus for delivering charge air to a four-cycle internal combustion engine.
BACKGROUND ART
The use of turbochargers to increase power output and decrease fuel consumption in four-cycle internal combustion engines is common practice today. Both spark ignition and diesel engines use turbochargers to advantage and, in the case of diesel engines, the power output of an engine of a given cylinder displacement can easily be doubled by the addition of turbocharging with aftercooling. The turbocharger has gone through decades of development, and modem turbochargers used on high-speed diesel and gasoline engines are relatively low in cost and high in efficiency, and are durable commercial products.
Although the turbocharger utilizes exhaust gas energy that would otherwise be wasted, the imposition of an exhaust gas turbine in the engine exhaust system necessitates raising the average back pressure on the engine cylinders in order to generate sufficient pressure drop across the turbine to generate the power necessary to drive the turbocharger's compressor. This back pressure acts against the upstroke of the piston as it forces residual products of combustion out of the cylinder through the exhaust valves and increases the pumping loss of the engine. The level of back pressure caused by high pressure turbocharging of four-cycle engines is very high, even with the use of turbochargers that have relatively high overall efficiency. Any means that may be employed to lower the back pressure caused by the turbocharger turbine can result in significant improvement in engine performance. For example, if a diesel engine requires a pressure ratio of 2.5 times atmospheric pressure to reach the desired rated engine power output, a single turbocharger would impose a back pressure in the exhaust system of approximately two times atmospheric pressure.
The use of series turbochargers is common today on engines that are rated in high power output. If the two compressors are placed in series combination, the pressure ratios of the compressors are multiplied so high supercharge pressure can be supplied to the engine beyond that which a single turbocharger could produce by itself. If, for instance, a highly rated engine requires 4.5 pressure ratio, which is beyond the capability of a single commercial turbocharger, series turbochargers can provide a low pressure stage of 2.1 pressure ratio and a high pressure stage of 2.15 pressure ratio, the product of which is 4.51 pressure ratio overall. This, however, significantly raises the exhaust gas back pressure.
DISCLOSURE OF THE INVENTION
The invention is directed to charge air systems that may include a small electric motor-driven compressor for supplying charge air to four-cycle internal combustion engines, including systems with turbocharger charge air compressors in series and parallel connection. Charge air systems of the invention can provide an effective charge air flow path to the internal combustion engine that avoids the air flow restriction of a small charge air compressor and a need for its continuous operation to avoid the restriction effect of a small charge air compressor.
The invention permits the use of a small motor-driven compressor to provide charge air at engine speeds from idle to about 2000 to 2500 rpm without restricting charge air flow to the engine at high engine speeds, and permits such uses with a small motor-driven compressor in series and in parallel with a turbocharger compressor. The small motor-driven compressors used in this invention are compressors having an air output capacity that is incapable of supplying the charge air requirements of an internal combustion engine operating at high engine speeds, for example, in excess of about 2500 rpm, and would present an unacceptable restriction to charge air flow at such engine speeds in the absence of their operation. The invention permits the use of charge air compressors capable of supplying only a third, or less, of the charge air requirements of a four-cycle internal combustion engine operating at full rated speed.
A charge air system of the invention includes a small charge air compressor having an inlet and an outlet, an electric motor connected to drive the charge air compressor, a first charge air conduit connected with the outlet of the charge air compressor, a second charge air conduit and junction for the first and second charge air conduits, with the junction being connected with the intake manifold of a four-cycle internal combustion engine, and a charge air check valve located at, or upstream of, the junction for one of said first and second charge air conduits. In one preferred charge air system of the invention, the inlet of the small charge air compressor and the second conduit are connected with ambient atmosphere, preferably through an air cleaner, and the charge air check valve operates to close the second charge air conduit upon operation of the charge air compressor.
Another such charge air system of the invention provides two-stage compression with a turbocharger, having an exhaust gas driven turbine and a turbocharger compressor, driven by the exhaust gas driven turbine, with its air inlet connected with the junction and its compressed air outlet connected with the intake manifold of the internal combustion engine. In such preferred two-stage charge air systems, the turbocharger may be provided with an electric motor assisting the exhaust driven turbocharger turbine in driving the turbocharger compressor.
Another parallel operating charge air system of the invention includes a charge air compressor having an inlet and an outlet, an electric motor connected to drive the charge air compressor, a first charge air conduit connected with the outlet of the charge air compressor, a turbocharger having an exhaust gas driven turbine connected with the exhaust gas from a four-cycle engine and a turbocharger compressor having an air inlet and a compressed air outlet, a second charge air conduit connected with the compressed air outlet of the turbocharger compressor, a junction for said first and second charge air conduits, with the junction being connected with the air intake manifold of the four-cycle internal combustion engine, and a charge air check valve located at, or upstream of, the junction for one of said first and second charge air conduits. In preferred embodiments of such parallel operating charge air systems, the charge air check valve can close the second charge air conduit upon operation of the charge air compressor at low internal combustion engine speeds and close the first charge air conduit at high internal combustion engine speeds. Further, in such preferred charge air systems the turbocharger can include an electric motor assisting the exhaust gas driven turbocharger turbine in driving the turbocharger compressor.
Still another charge air system of the invention includes a charge air compressor having an inlet and an outlet, an electric motor connected to drive the charge air compressor, a turbocharger having an exhaust gas driven turbine connected with the exhaust gas from the four-cycle internal combustion engine and a turbocharger compressor having an air inlet and a compressed charge air outlet, a charge air cooler having its inlet connected with the compressed charge air outlet of said turbocharger compressor, a first charge air conduit connected with an outlet of the charge air cooler, a second charge air conduit connected with ambient atmosphere, a junction for the first and second charge air conduits, a third charge air conduit connecting the junction of the first and second charge air conduits with the air inlet of the charge air compressor, and a charge air check valve operable to open said second charge air conduit upon operation of said charge air compressor and to close the second charge air conduit upon operation of said turbocharger at high engine speeds. In such systems, the turbocharger may be provided with an electric motor assisting the exhaust gas turbine in drivi
Halimi Edward M.
Woollenweber William E.
Brinks Hofer Gilson & Lione
Honeywell International , Inc.
Koczo Michael
LandOfFree
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