US2088923A - Internal combustion engine - Google Patents

Description

- V. RAFATLOFF' I I v INTERNAL COMBUSTION ENGINE I Filed Feb. 4, 1935 Patented Aug. 3, 1937 UNITED STATES INTERNAL COMBUSTION ENGINE Valerien Bai'ailofl, Paris, France Application February 4, 1935, .Serlal No. 4,818

' In France February 6, 1934 2 claims. ,The present invention has for its object a new method of supercharging 4-cycle internal combustion engines and is intended to improve the conditions of operation of the compressor. The.

present invention enables the present method of supercharging aeroplane, automobile engines, etc. to be simplified and improved. Furthermore, it permits introducing into the cylinder arm kind of fuels, even those which do not mix with each other.

The compressors used hitherto for superchargingengines generally operate with a very high output and. at a speed of rotation of about 30,000

revs. per minute. It is obvious that such conditions of operation are harmful to the safety of operation of the engine and it can be considered that an engine which is supercharged in this manner can only be used for exceptional performances, without it being possible to use it in current practice. i

The method of supercharging according to the invention enables, for a given motor, and for a given compressor, the output and the speed of rotation of the compressor to be reduced while still obtaininga. perfect supercharging.

The method according to the invention is essentially characterized by the fact that the fuel is fed to the engine in two diflerent operations. The first charge of fuel is sucked in, in the usual so manner, through the inlet valve placed in the cylinder head. It is known that in this manner the co-efficient of filling. of the cylinder is always less than one. The second charge oi. fuel is let into. the engine, according to the invention, through holes drilled in the cylinder wall near the lower dead center of the piston, which holes are uncovered by the piston at the end of its downstroke. Said holes are placed in communication through a suitable conduit, with a compressor 40 and an auxiliary carburettor.

In this manner, when .the piston, after having sucked in the charge supplied by the usual valve, reaches its lower dead centre, it uncovers the holes provided in the cylinder wall, and the second charge is introduced into the cylinder.- The inlet of said second charge will continue as long as the holes are not again closed by the piston at the beginning of its upstroke.- It will readily be understood that theco-eificient of filling is thus considerably increased. The operation of the engine during the other phases is. the same as that of ordinary engines. At the end of the expansion stroke, the holes provided in the cylinder wall will be uncovered again by the piston and an additional introduction will occur 01' the mixture supplied by the compressor and the auxiliary carburettor. By varying the shape of the cam and the diameter 0! the exhaust valve, any desired pressure can be obtained within the cylinder when the piston un-. covers the ports and in particular such pressure can be made. less than that created by the compressor, so that the latter always delivers into thecylinder when it is placed in communication with same.

The gases thus introduced into the cylinder, owing to their nature being different from that oi'the burnt gases, will form above the piston a cushion which will finally drive out the burnt gases during the exhaust stroke of the piston. In this manner the scavenging of the inside 01' the cylinder and the evacuation of the burnt gases will be efiected in apcrfect manner. on the other hand, the temperature of the ga which remain in the combustion chamber at the end of the exhaust stroke and which will consist of the above-mentioned cushion of gas, will be less than that of the usual burnt gases. Consequently the temperature of the mixture, during its inlet and, consequently, during the compression, is reduced in the supercharged engine according to the invention." It will readily be understood that with a the supercharging system according to the invention, the compressor operates under much more favorable conditions than in the present supe'rcharging systems. In the present systems, the compressor supplies the supercompressed carblllant mixture ou h the inlet valve throughout the whole of the inlet stroke which corresponds substantiallyto an angle of rotation of the crank shaft of 200 to 220 under a pressure of the order of two atmospherw. With the system according to the invention the compressor supplies the combustible mixture to the cylinder only when the piston uncovers the above-mentioned holes. This period or opening. taking into account the progressiveneas of the opening and the closing of said holes by the piston. only corresponds to an angle oirotation o! the crankshaft or 50 to Taking into account, on the other hand, the diflerence or pressure which is considerable since, according to the invention, it sutfloes to compress the; additional mixture to 1.2 'or 1.3 atmospheres, it will readily be understood that the work of the compressor, according to the invention, will be 8 to 10 times less great than the work of the compressor in the present systems operating under the same conditions.

Thus the compressor can operate under absolutely normal conditions with 4,000 to 6,000 revs. per minute, while ensuring all desired safety.

On the other hand, it is known that an engine cannot be supercharged, from the point of view of economy and thermal efllciency, without making use of supercompression. But the supercompression necessitates having recourse to antidetonating substances such as tetraethyl lead. The presence of such antidetonating substances has a harmful action on the valve, conduits etc. The supercharging method according to the invention enables such harmful antidetonators to be replaced by harmless antidetonators which could not be used hitherto owing to the fact that they do not mix with gasolene. Thus for example, a solution of water in alcohol, the vapour of which can be compressed up to 13 atmospheres, does not mix with gasolene. On the other hand, its vapours can mix freely with gasolene vapours. Thus if, in the method according to the invention, a normal carburant mixture is supplied to the usual inlet valve and alcohol vapours through the holes drilled in the cylinder wall, a perfect antidetonating combustible mixture can be obtained. In general, any mixture possessing antidetonating properties can be supplied through the holes drilled in the cylinder wall and even pure water or H202 which forms a perfect antidetonator and which does not harmfully afl'ect the operation of the engine, while lowering the temperature of same. Oxygen can also be supplied through the holes. According to the invention, the compressor can be eliminated and the holes provided in the cylinder wall can be put in communication with the atmosphere by a suitable conduit. The supercharging and scavenging are in that case ensured by the inertia eifect of the air or mixture passing through such conduit and which, when the holes are closed by the piston, produces in the conduit near the piston over-pressure causing a fresh inrush of air or of mixture in the cylinder when communication with the cylinder is again established.

The invention will be better understood with the help of the accompanying drawing in which I have shown by way of example three embodiments of the invention.

In Fig. 1 is shown in vertical section an engine equipped according to the invention.

In Fig. 2 a modified construction is shown in which the second carburettor is replaced by a simple jet placed in the inlet piping.

In Fig. 3 a third embodiment is shown in which the compressor is eliminated.

Referring first of all to Fig. 1, I is the cylinder, 2 the piston, l8 its connecting rod, and I! the crank case of the engine. Theusual inlet valve is shown at 5, the exhaust valve at 6, and the exhaust pipe at 4. The usual carburettor is' shown at I! and is connected with the valve 5 by a pipe 3. Towards the end of its downstroke, the piston 2 uncovers holes provided in the wall of the cylinder I and which communicate through a pipe 8 in which is placed a butterfly control valve 0, with a compressor l0 and an additional carburettor II.

In the example of Fig. 2, the carburettor II is replaced by a simple jet l4, communicating through a pipe II with a fuel tank It; a cock I! enables the supply of fuel to be controlled.

In the case of Fig. 3, the compressor I0 is eliminated, and the automatic supercharging and the scavenging are ensured by the inertia of the moving fresh air or antidetonating gaseous mixture in the pipe 8 which then places the ports 'I of the engine cylinder in communication with the outer atmosphere.

When the piston 2 at the end of its suction stroke uncovers the lower ports 1, the outer air or mixture, whichhas a pressure greater than that of the cylinder I, enters the cylinder and produces the supercharging. When the piston '2 again covers up the ports 1, the current of air or of mixture passing through the pipe 8 being then suddenly interrupted, an increase of pressure due to the inertia of the gas occurs in the portion of the pipe 8 near the piston 2, and which, when the piston uncovers the ports 1, towards the end of its next downstroke, causes a new inrush of gas in the cylinder i, thereby facilitating the scavenging of the burnt gases.

As in the engine having a compressor, by suitably calculating the diameter of the exhaust valve and the shape of its control mechanism, the pressure in the cylinder for the period in question, can be determined and obtained at less than atmospheric pressure.

I claim:

1. The process of operating a four-cycle internal combustion engine which comprises introducing a primary charge of fuel mixture into the combustion chamber of a cylinder during at least the greater part of the intake stroke, introducing a supercharging charge into the combustion chamber near the end of the intake stroke, compressing the composite charge, exploding the compressed charge, reducing the pressure in the combustion chamber of the cylinder during the latter part of the power stroke resulting from said explosion, and thereafter introducing fuel mixture into said combustion chamber adjacent the piston head when said piston head is adjacent the lower dead center position of the power stroke to replace the products of combustion adjacent said piston head and form a covering cushion of fuel mixture above the piston head to assist in more effectively expelling products of combustion at the end of the exhaust stroke.

2. The process of operating a four-cycle internal combustion engine, which comprises introducing a primary charge of fuel mixture into the combustion chamber of a cylinder adjacent the top of said cylinder, introducing a supercharging charge into the combustion .chamber adjacent the top of the piston head when said piston head is adjacent the. lower dead center position of the intake stroke, compressing the composite charge, exploding the compressed charge, and thereafter introducing a fuel mixture into said combustion chamber adjacent the piston head when said piston head is adjacent the lower dead center position of the power stroke to replace the products of combustion adjacent said piston head and form a covering cushion of fuel mixture above the piston head to assist in more eifectively expelling products of combustion at the end of the exhaust stroke.

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