Two- and four-stroke engines

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%).

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Wikipedia