Power plants – Fluid motor means driven by waste heat or by exhaust energy... – With supercharging means for engine
Reexamination Certificate
1999-02-22
2001-05-22
Wolfe, Willis R. (Department: 3747)
Power plants
Fluid motor means driven by waste heat or by exhaust energy...
With supercharging means for engine
C123S568110, C123S568200
Reexamination Certificate
active
06233936
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an internal combustion engine, comprising an inlet manifold and an exhaust manifold, respectively, opening into inlet ducts and exhaust ducts, respectively, to the engine cylinders, a charging unit, the pressure side of which is connected to an inlet air conduit opening into the inlet manifold; and a conduit for recirculation of exhaust from the exhaust side of the engine to its inlet side.
In supercharged internal combustion engines, e.g. turbo engines, the charged pressure of the intake air in the intake manifold is often higher than the mean pressure of the exhaust in the exhaust manifold, which means that conventional shutter and valve devices used in suction engines cannot be used in supercharged engines to transfer exhaust to the pressure side of the compressor. It is known to achieve this to use some type of pressure increaser on the exhaust side, e.g. constriction in the form of a turbo unit with variable geometry, or some form of pump device.
If the principle of pressure increase is used, this means that the engine will work against a pressure with its entire exhaust flow to return only a fraction of the flow, approximately 10%, to the inlet side, which results in an undesirable loss of efficiency. The principle with the pump, in addition to the extra cost and complexity, involves a parasitic loss corresponding to the rise in pressure of about 10% of the exhaust flow divided by the efficiency of the pump, i.e. a total of approximately 20% of the exhaust flow times the rise in pressure.
SUMMARY OF THE INVENTION
The purpose of the present invention is to achieve an internal combustion engine of the type described by way of introduction, in which exhaust can be returned to the inlet side without any loss of efficiency and with much simpler and less expensive means than a pump device.
This is achieved according to the invention by virtue of the fact that the recirculation conduit communicates with valve means and that valve control means are arranged, during such operating conditions where the exhaust is to be recirculated, to only permit the valve means to open when the exhaust pressure in the manifold is higher than the air pressure on the pressure side of the charging unit.
The invention is based on the insight that the pressure during the pressure pulsations in the exhaust manifold has pressure peaks, which exceed the charge pressure in the inlet manifold, and use valve means which open at these pressure peaks but are kept closed therebetween to prevent inlet air from flowing to the exhaust side.
In its simplest form, the valve and control means can be non-return valves.
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patent: 1-177446 (1989-07-01), None
AB Volvo
Wolfe Willis R.
Young & Thompson
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