http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
흡배기압과 실린더압의 동시 측정을 통한 다기통 CAI 엔진의 흡배기 유량 및 실린더 내 잔류가스 Online 예측 모델의 개발
기민영(Minyoung Ki),최승목(Seungmok Choi),민경덕(Kyoungdoug Min) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
CAI (Controlled Auto Ignition) engine has properties of higher efficiency and lower emission than conventional gasoline engine. However, CAI combustion control is difficult, because the combustion is mainly controlled by in-cylinder residual gas fraction (RGF) which cannot be controlled directly. In-cylinder RGF is usually controlled using variable valve actuating System (VVA), by adapting low lift cam, short valve duration and negative valve overlap. So, it is very important to predict RGF accurately and quickly in developing CAI engine. In this study, an online model for predicting RGF using measured intake, exhaust, and cylinder pressure has been developed. By measured three points of dynamic pressures as pressure boundaries of pipe inlets and outlets using labview DAQ system. This model could calculate directly RGF in 10 seconds without solving complex and computationally expansive energy equations during engine experiment. Calculations of mass flowrate and RGF in various CAI combustion conditions were done, and the results were compared with GT-Power results.
EGR 변화에 따른 CAI 엔진 연소 소음 저감에 관한 연구
김성욱(Seonguk Kim),기민영(Minyoung Ki),이윤(Yoon Lee),민경덕(Kyoungdoug Min) 한국자동차공학회 2008 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Controlled Auto Ignition (CAI) engine, which is still on developmental stage, is widely known to have higher efficiency and lower emission than conventional gasoline engine. A few problems (such as ignition control and operational range) are still holding back the CAI engine from commercialization, and combustion noise, which is the main subject of this study, is one of them. Since a significant portion of the CAI engine combustion process is similar to that of a conventional SI engine under knocking condition, large noise just might seem inevitable. Although self-ignition of gasoline in CAI engine is different from SI engine in that it is intentional, the fact that self-ignition occurs almost simultaneously in several different locations within the clearance volume and causes large pressure gradient, is the same. To achieve possible noise reduction in CAI combustion, cooled EGR was used as the potential sound reducing additive in the experiments of this study. In order to simulate the effects of cooled EGR in our experiment, commercially charged carbon dioxide with 99% purity was used. In the various cases of our experiment, CO₂ gas was injected through the intake port at various volumetric percentages ranging from 0 to 2%. As a result, correlation between pressure gradient and effect of cooled EGR was found in this research while IMEP was maintained at a similar level.
흡배기 및 실린더압 동시 측정을 통한 CAI 엔진의 흡배기 유량 및 실린더 내 잔류가스 예측 모델
최승목(Seungmok Choi),기민영(Minyoung Ki),민경덕(Kyoungdoug Min) 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
CAI (Controlled Auto Ignition) combustion has many advantages such as high efficiency and low emission characteristics. However, there are many difficulties in controlling CAI combustion, because combustion is mainly controlled by in-cylinder Residual Gas Fraction (RGF) which cannot be controlled directly. RGF is usually controlled using Variable Valve Actuating System (VVA), by adapting low lift cam, short valve duration and negative valve overlap. Predicting RGF accurately and quickly is very important in developing CAI engine. However, on-line prediction of RGF is not always practical, due to expensive fast response exhaust gas analyzers are required and some theoretical models are too slow to adapt. In this study, a model for predicting RGF using measured intake, exhaust and cylinder pressure has been developed. By using measured three points of dynamic pressures as pressure boundaries of pipe inlets and outlets, this model could calculate RGF in 5 seconds without solving complex and computationally expansive energy equations. Calculations of mass flowrate and RGF in various CAI combustion conditions were done, and the results were compared with GT-Power results.