The rotary engine is very different from the current reciprocating engine. Its piston is an eccentric rotor that rotates in a cylinder shaped like a jujube pit. The rotor is triangular, the piston rings at the three sharp points are always in contact with the cylinder wall, and the three surfaces of the rotor and the inner wall of the corresponding cavity form three combustion chambers, and their volumes are always changing during the rotor rotation. This structure no longer needs a crankshaft and a valve, and the only moving part is the rotor piston. Obviously, it is simpler and more compact than the traditional engine.
The crankshaft of the traditional four-stroke engine rotates twice to complete a working cycle, while the rotor of the rotary engine can complete four strokes only by rotating once, and the rotor itself can transmit power to the output shaft, so there is no need for an additional crankshaft. The compact structure makes it benefit from both quality and size. A rotary engine with more than one rotor will work very smoothly. If the double-rotor engine is arranged at an included angle of 180 degrees, it can achieve a nearly perfect mass balance, which is smoother than the traditional 6-cylinder engine and hardly feels vibration.