The characteristic of rotor motion of rotary engine is that the center of triangular rotor rotates around the center of output shaft, and the triangular rotor itself also rotates around its center. When the triangular rotor rotates, the internal gear ring centered on the triangular rotor meshes with the gear centered on the output shaft, and the gear is fixed on the cylinder body and does not rotate. The ratio of the number of teeth of the internal gear ring to the number of teeth of the gear is 3:2. The above motion relationship makes the motion trajectory of the apex angle (that is, the shape of the cylinder wall) of the triangular rotor like an "8". The triangular rotor divides the cylinder into three independent spaces by using the top angle of the rotor, and the three spaces complete intake, compression, work and exhaust in turn. The triangular rotor rotates once, and the engine ignites and does work three times. In this way, everyone can understand the motion relationship of the rotor. Its output shaft speed is three times that of the rotor, which is completely different from the motion relationship between the piston and crankshaft of the reciprocating engine 1: 1. Because there is no high compression ratio of reciprocating engine, combustion cannot be sufficient. Although Mazda once added single turbocharging and double turbocharging to the rotary engine, it only increased the output horsepower and moderately reduced the exhaust emissions, but there is still a big gap with the reciprocating engine.
2 Short life of parts and components
Because the three top corners of the rotor are responsible for sealing (there are also seals similar to piston rings on the top corners), they work under poor lubrication for a long time, leading to premature wear. Although many schemes have been improved, such as ceramic cylinder wall (ceramic cylinder wall surface can reduce friction, and it is more resistant to high temperature without lubrication), and screening sealing materials at three corners. There is still no better breakthrough. The problem of high temperature of the output shaft in the middle of the rotor has been puzzling engineers.
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