An internal combustion engine is known, consisting of a body in its upper hollow part performed as an internal cylindrical space whereas in its lower part it is shaped a casting containing a crankshaft possessing three eccentric journals as the two end journals are opposites to the central journal, said crankshaft has three connecting rods and their lower ends are journaled on the crankshaft eccentrics. To the upper ends of the two outer connecting rods it is attached a long hollow piston having an internal cylindrical space whereas to the upper end of the central connecting rod it is connected a little piston situated within the internal cylindrical space of the long piston, as in the upper part of the body is shaped a combustion chamber where a sparking plug is situated, and the working piston is performed with an upper part, the diameter of which is smaller, and with a lower part having a greater diameter, the lower part contains the compressor piston journaled through a connecting rod and said compressor piston is diametrically opposite to the working piston journaled through two conrods that are suspended through journals to the crankshaft as between the face of the compressor piston and the inner cylindrical part of the working piston it is formed a variable inner space, the upper part of the working piston, below the segments, has a port which at the TDC is situated a front of the inlet port whereas at the BDC the exhaust port is situated above the lower part of the working piston whereat the working piston is journaled diametrically opposite to the compressor piston through two conrods suspended through journals to the crankshaft.

The disadvantages of the engine follow froms weighted and complicated crank mechanism, the larger overall dimensions of the engine, the increased friction because of more friction surfaces. Producing of multicylinder variants of a piston engine such as V-type engines, radial engines, boxer engines etc., is difficult. As well, the piston is weighted because of a tubular prolongation in its upper part and the overall height of the engine is higher.

The task of the present invention is the elaboration of an internal combustion engine possessing to a large degree a simplified construction with reduced over dimensions, a simplified and light crank mechanism allowing a facilitated and technological manufacturing of multicylinder variants of internal combustion engines.

In conformity with the invention, this task is achieved with a internal combustion engine consisting of a body, the upper part of which contains a working piston connected through a conrod to the corresponding journal on a crankshaft placed in the lower part of the body, said lower part is shaped as a casing whereas the compressor piston is situated within the inner space of the working piston and the compressor piston is fixed to the upper part of the body through a hollow stem having an inner transfer port as the inner transfer port is disposed below the intake valve, and between inner cylindrical part of the working piston and compressor piston face it is formed a variable inner space through which the sucking and supercharging of the air-fuel mixture are taking place, in the upper part of the body below the inlet port it is disposed an exhaust port which is above the upper part of the working piston at its BDC.

The advantages of the internal combustion engine are as follows: it has a light and simplified crank mechanism and this allows manufacturing of a internal combustion engine with reduced weight and over dimensions and with better efficiency because of less number of the friction details.

More in detail the invention is explained with the help of model implementation of the internal combustion engine shown in the enclosed figures as follows: Figure 1 shows a cross-section of the engine in the upper dead centre of the working cylinder; Figure 2 shows a cross-section of the engine while the working cylinder is in a moment of expansion (compression) of the air-fuel mixture; Figure 3 shows a cross-section of the engine in the bottom dead centre.

As it is shown on the Figure 1, the internal combustion engine is built by a body /1/ in its upper part is placed a working piston /2/ connected through a conrod /3/ to a corresponding journal /4/ on the crankshaft /5/ placed in the lower part of the body /1/, said lower part is shaped as a casing /6/ whereas the compressor piston /7/ contained within the space of the working piston /2/ is fixed through a stem /8/ to the upper part of the body /1/ as the stem /8/ is hollow and it has an inner transfer port /9/ located below the intake valve /10/, and in the lower end of the hollow stem /8/ there are located overflow ports /14/, and between the inner cylindrical part of the working piston /2/ and compressor piston face /7/ it is shaped a space having variable inner volume in which the sucking and supercharging of the air-fuel mixture are taking place, in the upper part of the body /1/, below the inlet port /1 1 /, it is placed an exhaust port /12/ situated at the bottom dead centre above the upper part of the working piston /2/.

The engine is operating as follows: As it is shown on the Figure 1, the working piston /2/ of the engine is in the TDC while the compressor piston /7/ is at the most far removed and owing to the vacuum created in the inner space of the working piston /2/ a sucking of air-fuel mixture is produced by the intake port /9/ and the overflow ports /14/ through the valve /10/ and the intake port /11/, the fuel is injected by the nozzle /16/ and making an air-fuel mixture is taking place. All this air-fuel mixture is compressed in the inner space as a result of the displacement of the working piston /2/ downwards to the BDC, according to the Figure 2.

When reaching the BDC by the working piston /2/ and its maximum coming near to the compressor piston /7/, as it is shown on the Figure 3, the compressed air-fuel mixture in the inner space flows through the overflow ports /14/ into the combustion chamber representing the space formed between the upper part of the body /1/ and the working piston /2/ itself. The air-fuel mixture fallen into the combustion chamber of the engine is subjected to compression by the displacement of the working piston /2/ towards the TDC and when reaching it, according to the Figure 1, the mixture is ignited by the sparking plug /15/ and pushing the working piston downwards to the crankshaft it is doing the working stroke. At the opening of the exhaust port /12/, according to the Figure 3, by the working piston /2/, the burned gases flow out through the exhaust port /12/ and in the next moment the combustion chamber of the engine is filled with a fresh air-fuel mixture entering through the port /14/.

In this way is accomplished, with high pressure like to a fountain, a high-performance scavenging of the combustion chamber and afterwards the above described working process is cyclically and manifold repeated, doing the operation of the engine.

The high-efficiency operation of the engine is achieved owing to the coordination of a series of constructive and physical factors such as: lack of casing sucking and compressing; a reduced length of the sucking track; an absence of useless constructive spaces; a simplified crank mechanism and less number of friction details, as well as the operation as a double- stroke engine with pure fuel without oil.