Power plants – Fluid motor means driven by waste heat or by exhaust energy... – With supercharging means for engine
Patent
1994-05-06
1995-05-23
Bertsch, Richard A.
Power plants
Fluid motor means driven by waste heat or by exhaust energy...
With supercharging means for engine
60602, F02B 3344
Patent
active
054170680
DESCRIPTION:
BRIEF SUMMARY
The invention relates to an exhaust gas flow system for split exhaust gas flow in a four cylinder internal combustion engine with an exhaust-driven turbocompressor, and to a method used in this connection.
STATE OF THE ART
As a relatively close approximation it may be stated that there is an essentially linear relationship between the air consumption of an Otto engine and its output. It is therefore very important for the engine cylinders to be drained of all exhaust gases after the expansion stroke so that they can again be filled with the maximum quantity of air and fuel. The reduction in volume caused by the piston during the exhaust stroke forces out the exhaust gases remaining in the cylinder after the primary draining of exhaust gas occurring at the lower dead center. When the piston turns at the upper dead center after the exhaust stroke has been completed, it is important to dispose of as much of the exhaust gases remaining in the combustion chamber as possible. This is achieved when the intake valves of the cylinder is/are opened immediately before the upper dead center, and its exhaust valves is/are closed immediately after the upper dead center. During the time both the intake and exhaust valves are open an instantaneous, positive pressure drop must therefore be present above the engine, i.e. the pressure in the intake manifold must be higher than in the exhaust collector. If this is the case the engine is able to flush the combustion chamber of all the exhaust gases to allow subsequent refilling with air.
However, the vehicle engines in current use are not capable of draining completely these last remaining exhaust gases (residual gases), and considerable quantities of such residual gases therefore remain in the cylinder when refilling of air commences, which has a negative effect on the possible engine output. The quantity of residual exhaust gases therefore has a detrimental effect on both the specified mean pressure, torque and output.
As far as internal combustion engines fitted with an exhaust-drive supercharger of the turbocompressor type are concerned, i.e. the turbo engines mentioned below, problems arise when attempting to achieve the required performances because interference pulses are generated on the exhaust side of the engine. These interference pulses normally give rise to relatively large quantities of residual gases in the cylinders, which means that the performances aimed for, which might otherwise be achieved, are not possible because of the negative effect of the interference pulses.
In order to minimize the quantities of residual gas formed due to the interference pulses from the turbo engine, the aim should therefore be to reduce or avoid such interference pulses.
One method of prior art for attempting to overcome this problem is the evacuation, via a first exhaust valve in each cylinder, of a first exhaust pulse with the highest pressure directly to the exhaust turbine inlet, whereupon the remaining exhaust gases (the residual gases) are evacuated via a second exhaust valve in each cylinder, after the first-mentioned exhaust valve has closed, and are allowed to escape "freely" from the cylinder, i.e. without obstruction, through a separate exhaust port designed for this secondary exhaust flow.
Reference may be made to GB 2 185 286, for instance, as an example of such a method of prior art.
SUMMARY OF THE INVENTION
This invention relates to a further development of this method of prior art with a split exhaust period (split exhaust gas flow), and its objective is to optimise the exhaust system in a turbo engine, thereby improving performance, using the two exhaust valves in each cylinder which have now become increasingly common in vehicle engines, for example four cylinder turbo engines with 16 valves.
In the light of this the objective is to ensure that the flushing of each cylinder in the engine is not negatively influenced by the exhaust pulses from the other cylinders of the engine. This could improve the degree of filling and substantially increase the output o
REFERENCES:
patent: 4207742 (1980-06-01), Dommes et al.
Bertsch Richard A.
Freay Charles G.
Saab Automobile Aktiebolag
LandOfFree
Exhaust gas flow system for an internal combustion engine fitted 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 flow system for an internal combustion engine fitted, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Exhaust gas flow system for an internal combustion engine fitted will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2133267