Abstract: A novel rotary engine of the kind having a toroidal cylinder and a set of pistons on a rotating circular piston assembly provides instantaneous adjustment of the displacement volume of the engine by varying the intake and expansion stroke length on the circular path of the pistons through the opening and closing of valves into the engine cylinder under the control of an engine management system responsive to the speed/load conditions of the engine and the throttle position.

Abstract: A novel rotary engine has a single toroidal cylinder and a set of pistons on a rotating circular piston assembly. A rotating disk valve perpendicular to the toroid has a cutout position which periodically traverses the chamber to allow passage of a piston therethrough. The geometry of the pistons and the valve are arranged to minimize the residual volume, by altering the geometry of the chamber section formed between valve and piston and/or providing pistons which are mechanically extendible and retractable in synchronization with the opening and closing of the disk valve, to optimize engine efficiency and performance.