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Heat Rejection Data를 이용한 PTC (Powertrain Cooling) 성능 추정
민선기(Sunki Min),유창한(Changhan Yu) 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
It is important to consider powertrain cooling performance, when engine is applied to new vehicle. If the performance is poor, engine will be damaged by overheating. But, the development timing of engine is faster than timing of vehicle, it may be difficult to solve the problem. In this study the powertain cooling performance was estimated with some test and calculation data. First, the heat rejection test was conducted. From this test, the heat rejection data at required rpm and load was acquired. Second, coolant flow test was conducted. From this test coolant flow rate to radiator was measured. Then engine torque and rpm was calculated from vehicle load and speed. Vehicle load and speed was calculated from test mode. Then by comparing these data, the powertrain cooling performance was estimated.
민선기(Sunki Min) 한국자동차공학회 2014 한국자동차공학회 부문종합 학술대회 Vol.2014 No.5
As turbo-charged engines are more popular, engine cooling becomes more important. Turbo-charged engine makes more heat in a smaller volume compared to NA engines of similar power and needs more cooling because of bigger heat rejection. But turbo-charged engines have smaller water jacket and the surface area of water jacket which contacts with cooling water is smaller. In this study, coolant flow analysis was done with AMESim to improve coolant flow rate. At first, base AMESim model of cooling circuit was correlated with test result. After correlation was completed, various AMESim models were made by increasing diameter of hose and pipe connected to each part ? radiator, heater & oil cooler and T/C cooler. Flow rate of increased hose or pipe resulted in increasing of flow rate to connected part, but flow rate of other parts were decreased. To change flow rate distribution of each parts, the base cooling circuit was modified. By modifying cooling circuit, total flow rate to all parts decreased while flow rate to radiator was maintained.
Oil Jet System이 Engine Friction에 미치는 영향에 대한 연구
민선기(Sunki Min),김봉조(Bongjo Kim) 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
The purpose of the oil jet is to provide oil to the underside of piston for cooling and noise attenuation. If the oil jet is used, there are some additional considerations like oil flow rate, oil pressure and oil temperature. To solve these problems, oil cooler and oil pump size-up can be applied. But in this case, the friction torque will increase. In this study, it was confirmed that the friction torque increases as using the oil jet system - oil jet, oil cooler and oil pump size-up. Also the portion of friction torque by each part was measured by changing engine assembly condition. The friction torque by oil jet and oil pump size-up was similar. The friction torque by oil cooler was as twice as by others.
열방출량 (Heat Rejection Rate)을 이용한 PTC (Powertrain Cooling) 성능 추정
민선기(Min, Sunki) 한국산학기술학회 2015 한국산학기술학회논문지 Vol.16 No.5
새로운 엔진과 차량을 개발하여 엔진을 차량에 탑재할 때, 중요하게 고려해야 할 사항 중의 하나는 냉각 성능이다. 만약 냉각 성능이 열악하다면 엔진은 과열되어 파손되게 된다. 그러나 자동차회사에서 일반적으로 엔진은 차량보다 훨씬 빠른 시기에 개발이 진행되게 되어 엔진을 차량에 탑재한 조건에서 냉각 성능을 시험할 수 없다. 본 연구에서는 몇 가지 시험과 계산 결과를 이용하여 엔진의 냉각 성능을 추정하였다. 첫 번째로 엔진의 열정산 시험이 진행되었다. 두 번째로 냉각 수 유동 시험이 진행되었다. 이 시험에서 라디에이터로 유입되는 유량을 구할 수 있다. 그리고 차량의 냉각 시험 성능 조건으 로부터 차량의 부하와 속도를 구하고, 이로부터 엔진의 토크와 rpm이 계산되었다. 그리고 이러한 결과를 비교하여 엔진의 냉각 성능이 추정되었다. It is important to consider powertrain cooling performance, when engine is applied to new vehicle. If the performance is poor, engine will be damaged by overheating. But, the development timing of engine is faster than timing of vehicle, it is difficult to test the cooling performance of new engine and vehicle. In this study the powertain cooling performance was estimated with some test and calculation data. First, the heat rejection test was conducted. From this test, the heat rejection data at required rpm and load was acquired. Second, coolant flow test was conducted. From this test coolant flow rate to radiator was measured. Then engine torque and rpm was calculated from vehicle load and speed. Vehicle load and speed was calculated from test mode. Then by comparing these data, the powertrain cooling performance was estimated.
피스톤 헤드 온도에 오일 제트가 미치는 영향에 대한 연구
민선기(Sunki Min) 한국산학기술학회 2018 한국산학기술학회논문지 Vol.19 No.11
엔진의 성능이 향상될수록 엔진 내부에서 연소되는 연료의 양이 증가하고 그에 따라 엔진의 온도는 증가하게 된다. 특히 피스톤 헤드의 경우 냉각이 어려우므로 피스톤 헤드의 온도가 높아지게 된다. 그러나 피스톤 헤드의 온도가 너무 높게 되면 피스톤 헤드 표면에서 이상 연소가 발생하기 쉬워 토크 저하 및 엔진 파손과 같은 결과를 가져온다. 피스톤 헤드의 온도를 낮게 하기 위하여 오일을 피스톤 헤드 하단부로 분사하는 오일 제트가 사용되는데, 본 연구에서는 오일 제트에 의한 피스톤 헤드 냉각 효과를 확인하기 위하여 템플러그를 사용하여 엔진 작동시 피스톤 헤드의 온도를 측정하였다. 템플러그는 일종의 센서로 피스톤 헤드의 온도에 따라 템플러그의 경도가 변화하여 변화된 경도를 이용하여 피스톤 헤드의 온도를 측정한다. 템플러그를 사용하여 피스톤 헤드의 최고 온도를 오일 제트가 없는 상태와 설치된 상태에서 측정하였다. 오일 제트가 설치됨에 따라 피스톤 헤드의 온도는 변화되었다. 최고 온도 부위가 중앙부위에서 전후부위로 변경되었다. 또한 피스톤 헤드 내에서 온도 편차가 감소하여 좀 더 균일한 피스톤 헤드 온도 분포를 얻을 수 있었다. As the performance of engines improves, the temperature of engines is increasing, resulting in a high piston temperature. An excessively high piston temperature may result in torque drop or engine failure. An oil jet is used to reduce the piston temperature. In this study, to monitor the effect of oil jet, a templug was used to measure the piston temperature. A templug is a kind of sensor and the hardness of the templug changes according to the piston temperature. Using a templug, the maximum temperature of the piston was measured with and without an oil jet. The piston temperature was lowered using the oil jet. The highest temperature region changed from the center crown to the front/rear area. In addition, the temperature difference between the highest and lowest regions became smaller.