Isolated combustion and diluted expansion (icade) piston engine

Abstract

The 'Isolated Combustion and Dilution Expansion (ICADE) Engine', is a piston/cylinder arrangement used primarily for the compression of air and the expansion of diluted hot combustion products. Fuel injection and rapid combustion take place inside a separate combustion chamber, using a near stoichiometric mixture. The combustion pressurization provides the pressure needed to accelerate the combustion products tangentially into the donut shaped cavity formed by the piston/cylinder clearance. There they establish a vortex which enhances rapid mixing, rapid cooling to quench NO.sub.x forming reactions and to temporarily store the kinetic energy of the combustion products to limit the combustion pressure peak acting on the piston surface. The tangential entry also permits detonation combustion without normal shock reflections on the piston surface, thus preventing 'knock'. Only during the compression stroke, is the combustion chamber isolated from the piston/cylinder arrangement, by a valve with 'controlled leakage'. During the compression stroke, this 'leaky valve' keeps the combustion chamber pressure lower than the pressure inside the cylinder. This controlled pressure difference serves to: prevent fuel from escaping into the cylinder, produce good fuel mixing with combustion air, permits the use of low octane fuel at moderate compression ratio inside the combustor, while the cylinder operates at high compression ratio for high thermal efficiency. Power level control is obtained by modulating the 'leaky valve' to regulate the supply of combustion air, fuel flow control is separate. This configuration eliminates the need for a cylinder intake throttle valve.