Turbocharging systems for internal combustion engines

Abstract

Internal combustion engine systems can be provided with enhanced engine performance through improved two-stage charge air compression and through improved exhaust gas recirculation in relation to engine load and speed. Improved two-stage charge air compression can be provided with a turbocharger having an exhaust gas turbine and a first stage air compressor driven by the exhaust gas turbine and providing a flow of compressed air at its outlet and a second stage motor-driven compressor having its inlet connected with the flow of compressed air from the turbocharger compressor outlet and its outlet connected with the intake manifold to provide further and highly compressed charge air for the internal combustion engine. Improved exhaust gas recirculation can be provided with a two-input proportioning gas control valve connected in a two-stage charge air compression system to mix in controlled proportions a flow of air, which is preferably compressed air from a first stage compressor, and a flow of exhaust gas from the internal combustion engine and to deliver an EGR mixture of exhaust gas and air for compression as charge air for the engine. A control can be provided with engine operating signals and a signal from an EGR mixture sensor and can control the two-input proportioning valve and one or more motor-driven charge air compressors to provide an optimal EGR charge air mixture and to improve engine operating performance.