| Overview | Intro |
| Concepts | Illustrated |
| Side View | Operation |
| Single Chamber | Rotary vs. Piston |
| Pollution | Seals |
| Applications |
The requirements for sealing off various parts of the rotary engine from each other are quite different from the piston engine. The piston engine requires very tight seals because of the high compression ratio and because the seal separates a lubrication area from a combustion area. If lubricant leaks into the combustion area, it burns. Since the lubricant is much heavier than the usual fuel for the piston engine, the combustion is incomplete and a lot of undesirable combustion by products end up going out the exhaust.
In the rotary engine there are three seals enclosing the combustion chamber. One is formed by the vane and the combustion chamber wall. One is formed by the rotating valve plate and the combustion chamber wall, and one is formed located at the base of the vane where the lubricant for the vane bearings is sealed off from the combustion chamber.
Since the vane seal and the valve seal are not separating lube and combustion areas, the only consequence of a loose seal is loss of power. The perfect trade-off would be to have a seal that is tight enough so that the loss of power due to friction exactly balances the loss of power due to leakage. Though there might be some pollution consequences for having the seal too loose, they would be minimal because combustion only takes a few milliseconds to complete, so that most of the time the these seals were pressurized, any leakage would be thoroughly burned and no more polluting that the ordinary exhaust of the engine.
The third seal at the base of the vane suffers from the same leakage problem as the seals in the piston engine. But that could be reduced drastically by putting in a buffer chamber that was sealed off from the main combustion chamber and vented to the exhaust. I'm sure there are other methods of minimizing the leakage from this seal over time. This critical seal would be much smaller in the rotary engine than the same type of seal in the piston engine.
The problem of sealing a rotary engine probably has more in common with sealing a turbojet than a piston engine.