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피스톤 마찰과 마모 및 슬랩 소음에 미치는 설계 변수의 영향
오병근(Byoungkeun Oh),윤성호(Seongho Yoon) 한국자동차공학회 2004 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
This paper discusses the effect of engine design parameters on piston friction, wear and slap noise of a gasoline engine by piston dynamics analysis. The simulation model takes account of nonlinear interaction between oil film and elastic deformation of the lubricating surfaces. This is for enhancing the accuracy of results compared with those obtained with the rigid body model. Piston dynamics analysis has been performed using these parameters for several engine speeds. As the results, it is found that these parameters should be chosen to compromise the contradiction existing between friction, wear and slap noise, by considering the engine speed. This is because the tendency of change in friction, wear and slap noise is varied with the engine speed, unlike we expected.
가솔린 엔진에서 스퀴시 형상 적용에 따른 유동 특성 해석
박성호(Sungho Park),오병근(Byoungkeun Oh) 한국자동차공학회 2005 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2005 No.11_1
Squish flow is well known as an important technology for improving knock limit and performance in spark ignition engines. We have developed a slant squish combustion chamber for a new engine. From IVO to 80deg ATDC, the numerical analysis on three-dimensional, transient in-cylinder flow was performed to understand the squish flow patterns for a slant squish and flat squish configurations and we could prove the advantage of slant squish combustion chamber. Compared with a flat squish, a slant squish has high mean turbulent kinetic energy at the spark timing and produces effective reverse squish flow in the early expansion stroke. Through this study, it is possible to get the physical insight into the desirable squish flow patterns at spark timing. Experimental results show that HC and NOx are decreased in the slant squish type compared with the flat squish type.
김충식(Choong-sik Kim),오병근(Byoungkeun Oh) 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Variable Valve Timing (VVT) system is used to improve fuel economy, performance and emissions. This paper describes the effect of VVT in terms of performance for WOT condition and fuel economy related to residual gas content, intake manifold pressure and pumping losses for part-load condition. One dimensional engine cycle simulations are performed on 1.4L gasoline 4-cylinder engine by using GT-Power. Simulations showed reasonable results to understand physical phenomena of gas flow caused by valve timing changes. Also it was possible to reduce test cases for VVT calibrations. Maximum torque was increased 19.6% at 1200 rpm for WOT condition and BSFC 3.3% for 2000rpm BMEP 2bar condition through VVT optimization.
수치해석을 이용한 가솔린 엔진의 EGR 분배 특성에 관한 연구
김충식(Choongsik Kim),최지호(Jiho Choi),오병근(Byoungkeun Oh) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
EGR system has been often applied to engines to reduce NOx from exhaust emissions. As the EGR amount which is supplied to the engine increases, NOx emission shows a tendency of reduction. However, the excessive EGR supply causes lower fuel consumption and engine performance, and higher exhaust emissions due to the instability of the engine combustion. Therefore, the uniform EGR distribution is important in the case of multi-cylinder engines. It is difficult to predict the EGR distribution without real product, especially in the early stage of engine development. EGR distribution was predicted by CFD calculations in this study. CFD calculation results using 1D and 3D CFD code showed the acceptable EGR distribution.