Electro-pneumatic variable valve actuation system for camless engine: Part II-fuel consumption improvement through un-throttled operation

Abstract

Pumping loss during the gas exchange process becomes severe at low load operation in the conventional cam operated spark-ignition (SI) engine. In this study, the throttle body and conventional cam operated valve actuation mechanism of a single cylinder SI engine were removed. A novel in-house developed electro-pneumatic variable valve actuation system (VVA), as discussed in Part-I, was integrated and modified the conventional engine into camless engine. Air flow rates were varied using a throttle valve in the conventional engine. Whereas, for camess engine, air flow rates were varied by low intake valve lift and early intake valve closing (EIVC). It was found that the developed electro-pneumatic camless engine can inhale the same amount of air as compared to the conventional engine. The un-throttled operation in camless engine reduced the pumping loss at low engine speed and low load conditions, which helps in reducing the brake specific fuel consumption (BSFC) as compared to the conventional engine.