Advanced Downsizing of SI Engines: Promising Technology for Better Fuel Economy and Lower CO{sub}2 Emissions

摘要

The enhancement of fuel economy and CO{sub}2 emissions is the biggest challenge for engine and vehicle development. Downsizing is already a well-known technology to reduce the fuel consumption of combustion engines. First downsizing concepts were introduced into production with port fuel injection and a 25% reduction in displacement. These engines achieved a comparable power and torque characteristic together with approximately a 15% reduction in fuel consumption (C class vehicle on the NEDC). More recent production examples use advanced technologies for turbocharging, variable valve timing and gasoline direct injection, resulting in a>35% reduction in engine displacement and a>20% enhancement in the fuel economy on the NEDC. The critical area for full load performance and drivability (and thereupon the customer acceptance) is the steady state and transient low speed torque. To demonstrate the full range of capabilities for an advanced downsizing concept, a completely new demonstrator engine was designed. The selected displacement of this engine (V{sub}H = 1.2 l) is to suit 1,600kg vehicle applications. Its advanced approach is for 50% downsizing demonstrating a fuel economy improvement of approx. 30% in the NEDC over comparative N/A engines.