Basic Design of the Rand Cam Engine

The Rand Cam engine is a novel design which avoids the use of pistons in favor of a cavity of varying size and shape. A set of vanes protrudes from a rotor into a circular trough in a stator. The vanes seal to the walls and base of the trough, which is of varying depth, and progress around the trough with rotation of the rotor. These vanes therefore pass through the rotor and are constrained to move parallel to the rotational axis. Intake and exhaust processes occur through ports in the stator wall which are revealed by the passing vanes. Advantages of the basic design include an absence of valves, reduction in reciprocating masses, presence of an integral flywheel in the rotor and strong fluid movement akin a swirl induced by the relative velocity between the rotor and stator. A preliminary design has specified the depth profile of the trough as a function of rotational angle: This takes into account the requirements of the intake, compression, expansion and exhaust processes as well as the acceleration and motion of the vanes during rotation. Thicknesses of both the vanes and rotor are determined by the combustion forces acting on the trailing edge of the vanes and the frictional force experienced by the vanes as a result of movement around the trough. Rotor shape and trough cross-section are influenced by the need for a reasonable compression ratio while vane shape is governed primarily by the need to incorporate seals and the desire for simple manufacture. Lubrication of the vanes takes place through the rotor, which runs on bearings in the stators. Engine speed is limited by inertia of the vanes or by the combustion process in the chamber.