Charge air systems for two-cycle internal combustion engines

Abstract

A two-cycle internal combustion engine (,) has a motor-assisted turbocharger (,) where the motor (,) is activated by an external power source (,) to operate the turbocharger (,) to apply scavenging and charging air for starting the engine (,). When sufficient exhaust gas energy is available to allow the turbocharger (,) to provide adequate scavenging and charging air, the motor (,) is de-energized to eliminate the need for external power. Thus, the charging system acts as a supercharger during start-up and as a turbocharger during normal running. A control system (,) is connected to the driving motor (,) that receives signals (,) so that power is supplied to the motor (,) during start-up and may also be supplied during low exhaust gas energy levels to maintain a sufficient supply of scavenging and charging air. These signals (,) may come from engine speed, turbocharger speed, intake manifold pressure, throttle position and the like. In the case of a small crankcase-scavenged, two-cycle engine, a motor-driven compressor (,) may be used to augment the supply of scavenging air provided by the downstroke of the piston. A motor-driven compressor (,) can be arranged in series with a turbocharger compressor (,) to provide high pressure charge air to a two-cycle engine by virtue of being connected in series.