Concepts

The rotary engine is a negative compression engine. Combustion occurs at slightly less than atmospheric pressure. Higher compression yields more power for a given size, but higher compression is achieved by adding more components and heavier components to an engine. It might be better to just increase the size of the cylinders rather than increase the compression. At least the matter should be studied with an open mind.

In a piston engine, there is one very intense explosion per power cycle. Because of the intensity of the explosion, and the compression that must be generated, the components of a conventional internal combustion engine must be both strong and heavy, and the tightness of the seals is extremely important. The energy that drives the engine is produced in only a few milliseconds of each cycle, and must be confined and stored. The confinement requires tight seals, and the storage requires heavy components to store kinetic energy. This all leads to engines that are both heavy and expensive.

Loss of seal in a standard internal combustion engine results in pollution because the seal has the oil filled "pan" on one side and the combustion chamber on the other side. In this respect, the rotary engine has more in common with the turbine in the jet engine than it does a standard piston engine. A rotary engine can be designed so that none of the seals enclosing the combustion chamber are between oil containing chambers and combustion chambers. Most of the seals in the engine are "naturally" that way, but there is one seal that would require an additional chamber between the combustion chamber and the lubricating chamber to maintain this isolation.

These seals between a combustion chamber and an exhaust chamber don't result in burning of the oil used for lubrication if they leak. Instead they result in a loss of power. There is a trade-off between the tightness of the seal and the amount of friction loss caused by the seal. If the seal is too tight, power loss from friction will be excessive. If it is too loose, power loss from leakage will be excessive.

Forces generated by a rotary engine would about one tenth as great as those of a conventional piston engine. It might even be possible to fabricate a MicroComubstion engine largely of sheet metal without the need for milled cylinders, depending on the characteristics desired in the finished product. It should be possible to manufacture a rotary engine at a fraction of the cost of a conventional piston engine. The rotary engine has far fewer and lighter parts than a conventional piston engine.

The rotary engine can use multiple low energy ignitions per revolution, in contrast to one ignition every two revolutions in the 4-stroke engine. In the rotary engine the number of ignitions per cycle can be determined by the program in the micro controller. Instead of having one intense explosion that must be confined and stored, there can be several much milder ignitions that can deliver a much more continuous stream of power with lower noise and waste energy. There is not a separate power and exhaust cycle, every cycle is a power cycle. Because the pressure differentials involved are much lower, the tightness of the seals is much less important. I believe that the rotary engine could be operated efficiently even if there were gaps between the walls of the combustion chamber and the “piston”. Actually the rotary engine doesn’t use pistons, but we’ll get into that later.

Because of these factors, I believe that the rotary engine would be much more fuel efficient, less polluting than and ordinary engine, but even if this were not so, there are other reasons that the rotary engine might be useful for certain applications.

One is that a properly designed rotary engine doesn’t have to be “started” or idle. It can begin to operate, even with a moderate load, merely by applying proper signals to its electrically operated fuel injectors and spark plugs.

Another is that the rotary engine is much quieter than a conventional engine. When the exhaust valves open in a piston engine, there is still residual pressure in the piston which creates noise and wastes energy. When the exhaust port opens in the rotary engine, proper programming can assure that the gasses inside the “cylinder” are nearly at atmospheric pressure, so there is very little noise, and very little wasted energy. Since there is no need to convert linear motion to rotary, vibration should be much less.

Also, the rotary engine should be much lighter than a conventional engine. Since combustion in the engines generates much lower pressures distributed over a greater part of the combustion cycle, the engine components don't have to be nearly as robust and heavy.

Finally, the rotary engine does not need fuel with no-knock additives since the exact timing of ignition is not required.