Four stroke rotary piston engine

The four stroke rotary piston engine comprises one pair of toroidal chambers (1, 2) provided with respective rotary pistons (3, 4) attached to a common power shaft (8), wherein the intake and compression strokes are performed in one of the toroidal chambers (1) and the power and exhaust strokes are performed in the other of the toroidal chambers (2). The intake/compression toroidal chamber (1) has an air intake (9) and the power/exhaust toroidal chamber (2) has a fuel injector (11), ignition means and an exhaust port (12). Thrust plates (5, 6, 7) are provided and actuated to respectively open and close the intake/compression and power/exhaust toroidal chambers (1, 2) synchronously with the movements of the respective rotary pistons (3, 4) therein. Compressed air is transferred from the intake/compression toroidal chamber (1) to the power/exhaust toroidal chamber (2) via a transfer pipe (10) just before ignition.