For the trochoid-motion rotary engine, also with a normal size combustion chamber, the expansion chamber is larger than the compression chamber, therefore, the initial air charge is light and a bypass valve on the compression chamber side alternatively also varies the “effective” compression ratio.

The design in which reciprocating engines are fitted with an oversize combustion chamber, perhaps double the size of that of current engines or perhaps even larger, which produces a very low compression engine is also alternatively applied to the epitrochoid-motion rotary engines. This feature, oversized combustion chamber, is alternatively applicable to other rotary engines such as trochoid-motion rotary engines rotating on a central axis.

More Detailed Operation of Rotary Engines

For rotary engines, the leading rotor lobe rotates past the inlet port and the light air charge is received and the port is then sealed from the compression chamber. At any point deemed proper between the sealing of the port and sealing of the combustion chamber, or even at its sealing, an ancillary high pressure, cooled air charge which has been prepared externally to the engine is injected by intake valves. The supercharging (supplement air) can be injected during the compression process early or late, but preferably late, prior to sealing of the combustion chamber.

Alternatively, the supercharging can be injected directly into combustion chamber after the chamber is sealed, with the valve being either an expansion valve or normal inlet valve.

Another alternate means of reducing or eliminating the initial air charge in the rotary engine is thus: an ancillary outlet valve and conduit, is selectively opened when desired or needed, (needed if fuel is mixed with the air), at the time air inlet port is closed by a lobe of the rotor from communicating with the compression chamber. This allows the inducted air or air-fuel mixture to be expelled by a lobe of the rotor through the outlet valve and conduit. This air or air-fuel mix is not wasted as the outlet valve and conduit conveys the expelled gases out of the compression chamber and returns it to the air intake and filter of the compressor.

This can be a first stage of compression with the outlet valve alternatively variable in its valve orifice and in this operating mode with the atmospheric inlet port being closed, supplying all of the air charge received by compressor, preferably controlled by an engine control module (ECM). These low compression engines receive low pressure air in the initial air intake process, which when compressed produces little heat-of-compression. Then a second portion of air or air-fuel mixture, that is received, highly compressed and cooled externally to the engine, is injected into the cylinder by an ancillary intake valve on top of any initial charge remaining. The high pressure charge is injected after the closure of the initial atmospheric intake valve.

The ancillary intake valve is then closed during the compression stroke at a point that the proper weight of charge necessary for the desired engine performance has already been received and will be trapped in the compression chamber. Intake valves are alternatively closed at a point between 25% and 75% or more of the compression process at which point is alternatively variable and varied according to engine power requirements, preferably controlled by engine control module ECM.