가변 밸브 timing과 duration이 가솔린 엔진 연비 특성에 미치는 영향

Abstract

An experiment was conducted to study the effects of valve events on the engine performance. A prototype gasoline direct injection engine was used to realize the independent control of four valve event parameters, namely intake valve opening (IVO), intake valve closing (IVC), exhaust valve opening (EVO), and exhaust valve closing (EVC). The EVO timing contributed to the optimization of the blowdown during the end of the exhaust stroke and the exhaust pumping work. The retardation of IVC timing allowed the engine to operate with wider throttle angle at fixed load condition, which reduced the pumping work significantly. The valve overlap was controlled with IVO and EVC. The pumping work decreased when the valve overlap position laid at the vicinity of top dead center (TDC) with sufficient valve overlap duration. The IVC and EVO played a dominant role in optimizing the fuel consumption characteristics compared to IVO and EVC. The IVC and EVO should be optimized in prior to the optimization of IVO and EVC.