It comprises one or more cylinders with pistons therein and mutually opposed power cams connected to respective first and second rotary shafts. The reciprocating pistons act on the power cams to impart a rotating motion to the rotary shafts. An attachment device is provided for connecting the rotary shafts to each other. The attachment device includes a shifting device for changing the relative angular position of the first and second rotary shafts. The result is engine distribution and compression ratio are changed dynamically.

A method for a combustion engine has a working cycle of three revolutions of the crankshaft. The method includes: feeding a fuel mixture into a combustion chamber of a cylinder while moving a piston from a second top dead-center to a first bottom dead-center; compressing an air-fuel mixture in the combustion chamber while moving the piston from the first bottom dead-center to a first top dead-center; burning the air-fuel mixture while moving the piston from the first top dead-center to a second bottom dead-center; compressing a gas mixture in the combustion chamber while moving the piston from the second bottom dead-center to the first top dead-center; burning the gas mixture while moving the piston from the first top dead-center to the first bottom dead-center; and expelling the gas mixture from the combustion chamber while moving the piston from the first bottom dead-center to the second top dead-center.

In a forming apparatus, movable journal dies and stationary journal dies retain rough journal portions of a preform blank therebetween, and reference crank pin die and movable crank pin dies contact rough crank pin portions thereof, and in this state, the movable journal dies and the movable crank pin dies are moved axially toward the reference crank pin die and the reference crank pin die and the movable crank pin dies are moved in a direction perpendicular to an axial direction. With this, weighted rough arm portions are axially compressed to reduce their thickness to that of weighted arms of a forged crankshaft, and the rough crank pin portions are pressed in the direction perpendicular to the axial direction to increase an amount of eccentricity to that of the crank pins of the forged crankshaft.

A method for a combustion engine has a working cycle of three revolutions of the crankshaft. The method includes: feeding a fuel mixture into a combustion chamber of a cylinder while moving a piston from a second top dead-center to a first bottom dead-center; compressing an air-fuel mixture in the combustion chamber while moving the piston from the first bottom dead-center to a first top dead-center; burning the air-fuel mixture while moving the piston from the first top dead-center to a second bottom dead-center; compressing a gas mixture in the combustion chamber while moving the piston from the second bottom dead-center to the first top dead-center; burning the gas mixture while moving the piston from the first top dead-center to the first bottom dead-center; and expelling the gas mixture from the combustion chamber while moving the piston from the first bottom dead-center to the second top dead-center.

In a forming apparatus, movable journal dies (10U, 10B) and stationary journal dies (9U, 9B) retain rough journal portions (Ja) of a preform blank (4) therebetween, and reference crank pin die (11) and movable crank pin dies (12) contact rough crank pin portions (Pa) thereof, and in this state, the movable journal dies (10U, 10B) and the movable crank pin dies (12) are moved axially toward the reference crank pin die (11) and the reference crank pin die (11) and the movable crank pin dies (12) are moved in a direction perpendicular to an axial direction. With this, weighted rough arm portions (Aa) are axially compressed to reduce their thickness to that of weighted arms of a forged crankshaft, and the rough crank pin portions (Pa) are pressed in the direction perpendicular to the axial direction to increase an amount of eccentricity to that of the crank pins of the forged crankshaft.