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Two-and-four stroke engines are engines that combine elements from both two-stroke and four-stroke engines. They usually incorporate two pistons.
The M4+2 engine, also known as the double piston internal combustion engine, is a new type of internal combustion engine invented by a Polish patent holder Piotr Mężyk.
The M4+2 engine took its name from a combination of the two working modes of the known engines, that is from the Two-stroke engine and Four-stroke engine. The two-stroke combustion engine is characterized by a simple construction and system of air load change as well as bigger index of power output. Unfortunately, its filling ratio is worse than in four-stroke engine. The ecological index of two-stroke engine is also unfavorable. The system of valves of the four-stroke engine is its disadvantage. The cylinders of both modules of double pistons engine have been joined along one axis with common cylinder head - in the form of the ring. The pistons are moved with different speed and with appropriate stage displacement. There are two crankshafts, which are connected with special transmission in shown solution. The four-stroke crankshaft is rotated with twice a speed of two-stroke crankshaft. The engine is named double pistons because of its construction - double pistons and crankshafts. In the M4+2 the advantages of both engines being connected are obvious; the pistons of the engine working in one combustion cylinder are set oppositely to each other, but in different modes. Although the projects of connecting two stroke modes in one cylinder were tried already a long time ago in the Opposed piston engine, the combination of the two different cycles had never been tried before. It turned out that the engine is not only able to work, but that the effects are very promising. The engine has a far greater efficiency over the break-even value known to combustion engines (ca 35%) and closer to the one associated with steam turbines or electric engines (ca 70%).
The other advantages are as follows:
- more efficient power production (150 Horsepower from 1000 cc of volume in the basic version)
- smaller fuel consumption
- prolonged stroke expansion
- possibility to change the compression parameters without having to stop the engine
- simplicity of construction
The idea was developed at the Silesian University of Technology, Poland, under the leadership of dr Adam Ciesiołkiewicz. It was granted a patent nr 195052 by the Polish Patent Office. The work with the new combustion engine has been done by IZOLING P.W. Company in cooperation with Silesian University of Technology in Gliwice. There are consultations with researchers from Technical University of Kraków, too. So far two working engine models have been made. The preliminary model is based on two existing engines (two-stroke motorbike engine and four-stroke small machine engine). This model confirms the rightness of two- and four-stroke engines connection. The second model is the functional model. It realizes the elaborated engine work conception. The new solution of combustion engine was presented during Scientific Conferences (KONES '2002, Seminary of bio - fuels 2003, etc.) and in mass media (journals, newspapers, TVP, radio). The hope to build modern and universal ecological engine with good technical parameters and low fuel consumption is connected with Double pistons internal combustion engine.