Double-rotor piston internal combustion engine

The utility model relates to a power machinery field, especially a rotor piston internal combustion engine, which is characterized in that two oppositely-arranged pistons can do the intermittent rotary motion around an inner shaft (or a main shaft) in a cylindrical-shaped cylinder to complete process of suction, compression, burst, and exhaust; two cylinder covers are disposed on two ends of a cylinder body, and are combined with the cylinder body, and the pistons together to form a power generation part of the engine; torques of pistons can be transferred to an outer shaft gear by piston gears fixedly disposed on the outside parts of small ends of piston sleeve shafts; the outer shaft gear is fixedly disposed on the outside parts of two ends of the outer shaft, and is engaged with the piston gears to form a power transmission part, which also can be formed by a planetary gear system; concave arc plates (or braking groove wheels) are disposed in inner sides of small ends of the piston sleeve shafts and protru