As its identify implies, the apex seal sits on the apex, or tip, of the Wankel rotary engine’s triangular rotor. As the rotor spins on the engine’s eccentric shaft, every of the triangle’s three apexes maintains contact with the within of the case’s semi-oval chamber.

The seal between the spinning rotor’s apexes and the case is crucial to engine operation in 3 ways. First, it creates a vacuum that pulls recent gasoline/air combination into the chamber. As the rotor advances by means of the combustion cycle, the combination compresses and combusts with the ignition spark. At this level, the apex seals obtain their best take a look at. Finally, the apex seals sweep the exhaust gasses from the chamber earlier than starting the cycle over once more. Poor sealing at any stage of the method degrades engine efficiency. 

Traditionally, apex seal producers employed quite a lot of supplies starting from forged iron to fiber-reinforced ceramics with various levels of success. Engineers proceed trying to find a cloth that balances put on resistance with optimum combustion chamber sealing.