Dual radius rotor for pre-mixed-charge rotary engine combustion

In a rotary piston, internal combustion engine having a rotary piston eccentrically mounted for rotation in a multi-lobe, trochoidal-shaped engine housing and defining, with the housing, intake, compression, expansion and exhaust working chambers, each of which vary in volume as the rotary piston rotates within the housing in combination with ignition means for initiating fuel combustion disposed within the housing at a point relative to the direction of rotary piston rotation preceding the lobe junction between the compression and expansion combustion-working chambers, the improvement comprising:

• a rotary piston comprising a plurality of contiguous, convex, arcuate peripheral surfaces which, in combination with said engine housing, define said combustion-working chambers;
• said rotary piston further comprising a plurality of apex seals and a plurality of side seals disposed between said rotary piston and said engine housing;
• each of said convex, arcuate peripheral surfaces defining a convex, arcuate rotor recess, said convex, arcuate rotor recess having a recess radius greater than a peripheral surface radius of said rotary piston;
• and
• said convex, arcuate rotor recess comprising a crescent-shaped cross-section.