Abstract: A rotary piston internal combustion engine of the Wankel type for reducing unburned detrimental components such as NOx, HC, CO, etc. in exhaust gas without decrease of engine performance which comprises a first combustion chamber communicating by means of a passage means with a second combustion chamber formed between a trochoidal inner peripheral surface of a housing and a side surface of a rotary piston, said first combustion chamber being formed radially outside of said trochoidal inner peripheral surface, the volume of said first combustion chamber being 35 to 65% of the sum of both said combustion chambers at the top dead center (T.D.C.) of the engine, a fuel injection nozzle and an ignition plug provided in said first combustion chamber, said passage means opening onto said trochoidal inner peripheral surface in the range of 15.degree. before the junction of the two arcuate portions of said trochoidal inner surface to 30.degree.

Abstract: Rotary piston type engine comprising a casing having a cavity defined by an inner peripheral wall of trochoidal configuration, a substantially triangular rotor disposed in said cavity for rotation with its apex portions in sliding contact with the inner peripheral wall of the casing to define working chambers of variable volume, a main combustion chamber disposed outside the cavity in the casing and connected with the working chamber in compression stroke, a single fuel injection pump connected through a main fuel injection nozzle to the main combustion chamber and through an auxiliary fuel injection nozzle to the working chamber in intake stroke, and a control valve for allowing fuel to flow through the auxiliary fuel injection nozzle into the working chamber during high load operation of engine.