Internal-combustion engines – Multiple cylinder – Cylinders in-line
Reexamination Certificate
2000-02-14
2001-10-30
Wolfe, Willis R. (Department: 3747)
Internal-combustion engines
Multiple cylinder
Cylinders in-line
C123S568110, C123S568150
Reexamination Certificate
active
06308666
ABSTRACT:
The present invention relates to an internal combustion engine with means for recirculating the exhaust and supercharge gases.
It is known that the level of polluting oxides of nitrogen (NOx) emitted by an internal combustion engine can be reduced by returning some of the exhaust gases to the inlet pipe using a valve placed on a branch of the exhaust manifold, this valve being controlled by a computer.
It is also known practice, particularly from patent application WO 95/14853, in a mechanically supercharged engine, to use the exhaust gas pressure wave to perform automatic supercharging through a post-filling effect. An engine of this kind is supercharged by a compressor driven by a turbine through which the exhaust gases pass, the turbine acting as a restriction on the exhaust so as to allow the pressure wave to perform the post-filling.
The subject of the present invention is an engine equipped with means which both allow the exhaust gases to be recirculated and allow pressure wave supercharging using the pressure wave of the exhaust gases and do so in a combustion engine which has no mechanical means of supercharging.
The subject of the present invention is therefore an internal combustion engine with no mechanical supercharging means, having n cylinders each equipped with a piston with a reciprocating translational movement, each cylinder being equipped with q exhaust valves and r inlet valves, q and r being whole numbers greater than or equal to 1, possibly differing from one cylinder to another, each cylinder, in an operating cycle, involving filling with air and fuel, combustion with subsequent expansion providing the energy delivered by the engine and exhaust for discharging the burnt gases, the exhaust valves of n cylinders being connected to p exhaust manifold branches so that, in one same branch of the manifold, n′ cylinders are connected with n′<n and p<n, characterized in that each exhaust manifold branch D,D′ is connected to the exhaust gas outlet by a shut-off member and is connected to the atmosphere by at least one vent valve SS and that each cylinder of the engine includes, in part of its operating cycle, three successive phases &phgr;1, &phgr;2, &phgr;3, the n′ groups of three phases for all of the n′ cylinders connected to one same manifold branch covering the entirety of an engine operating cycle, the said three phases being, for a cylinder C, defined as follows:
in the first phase &phgr;1, at least one exhaust valve and at least one inlet valve are open, at least one vent valve is open in the manifold branch connected to C, the shut-off member for the said manifold branch is closed, the piston of the cylinder C moves towards bottom dead centre so as to fill its cylinder;
In the second phase &phgr;2, the said shut-off member is closed as is (or are) the vent valve(s) of the said manifold branch, all the inlet valves are closed, at least one exhaust valve is open; at least one other cylinder C′ of the n′ of the same manifold branch has at least one exhaust valve open and is in its phase of emptying the exhaust gases, its piston moving upwards towards top dead centre, the pressure wave which, in the said manifold branch comes from the cylinder C′ in its exhaust phase, driving the air and possibly the burnt gases into the cylinder C which is not exhausting;
in the third phase &phgr;3, the said shut-off member is open, the vent valve or valves is (or are) closed, the exhaust and inlet valves of the cylinder C are closed, the piston of the cylinder C is travelling upwards towards top dead centre while the cylinder C′ connected to the same manifold branch has at least one of its exhaust valves open, all its inlet valves being closed, the upstroke of the piston of the cylinder C′ towards top dead centre causing its burnt gases to be emptied out through shut-off member; after which the cylinder C, during compression, moves into the combustion phase, its piston then being driven back, by the expansion of the burnt gases, towards bottom dead centre until it returns to the start of phase &phgr;1 of its cycle.
Advantageously, the engine according to the invention is characterized in that it includes: at least one exhaust manifold branch connecting at least two associated cylinders in which the pistons perform the same movement towards top dead centre or towards bottom dead centre; the said exhaust manifold branch being, on the one hand, fitted with at least one vent valve, controlled by any appropriate means and, on the other hand, connected to the exhaust gas outlet pipe with the interposition of a shut-off member also controlled by any appropriate means; the inlet, exhaust and vent valves and the shut-off members being operated in synchronism so that the following occur in the engine: the induction of air through the inlet valve in one cylinder that is performing the inlet stroke; the induction through the exhaust valve of the said cylinder of the exhaust gases which lie in the branch of the manifold associated with the cylinder, with the entry of air into the said branch through the vent valve; then the driving into the said cylinder through the said exhaust valve of the air previously let into the manifold branch by the vent valve, through the pressure pulse effect of the burnt gases of another associated cylinder, the exhaust valve of the latter being open, thus achieving supercharging; and finally the discharging of the remainder of the burnt gases from the associated cylinder to the exhaust manifold through the shut-off member placed in the open position.
As a preference, the engine according to the invention is a four cylinder engine operating on a four-stoke cycle, the said cylinders being synchronized in the order 1, 3, 4, 2, the said engine having two manifold branches each associating a pair of cylinders, each manifold branch having at least one vent valve and being connected to the exhaust gas discharge with the interposition of a shut-off member so that during the engine operating cycle, the following occur:
a) induction of air through the inlet valve or valves of the first cylinder performing the inlet stroke;
b) induction, through the exhaust valve or valves of the said first cylinder of the exhaust gases lying in the exhaust manifold branch associated with the said first cylinder, at least one vent valve of the said manifold branch being open;
c) induction of a certain amount of air into the said exhaust manifold branch;
d) opening of the exhaust valve or valves of the cylinder advantageously connected to the first cylinder with the entry into the corresponding manifold branch of a pressure wave which drives the gas lying in the exhaust manifold into the first cylinder through its exhaust valve or valves;
e) discharging of the exhaust gases from the cylinder advantageously connected to the first cylinder, these gases being expelled by the piston of the said cylinder into the exhaust gas outlet manifold through the shut-off member which is in the open position;
f) the inlet of fuel into the first cylinder filled, on the one hand, with fresh air let in by the inlet valve or valves and, on the other hand, with additional fresh air let in by the exhaust valve or valves, and finally with recirculated exhaust gas let in by the same exhaust valve or valves; followed by combustion of the air-fuel-recirculated gases mixture, the piston being driven down to bottom dead centre until it returns to the start of its cycle; in such a way that supercharging and, at the same time, exhaust gas recirculation, are achieved in order to reduce pollution.
In a first alternative form, the shut-off member B is controlled by any appropriate means which allows its instant and period of opening and of closure to be determined at will. In another alternative form, the shut-off member has a rotary plug with two openings separated by two zones, and may or may not be associated with a phase-shifting system, so that by determining the speed at which the plug turns and the dimensions of the openings, its instant and du
Connolly Bove & Lodge & Hutz LLP
Wolfe Willis R.
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