Seungsuk Oh

Real-Time IMEP Estimation and Control Using an In-Cylinder Pressure Sensor for a Common-Rail Direct Injection Diesel Engine

An in-cylinder pressure-based control method is capable of improving engine performance, as well as reducing harmful emissions. However, this method is difficult to be implemented in a conventional engine management system due to the excessive data acquisition and long computation time. In this study, we propose a real-time indicated mean effective pressure (IMEP) estimation method using cylinder pressure in a common-rail direct injection diesel engine. In this method, difference pressure integral (DPI) was applied to the estimation. The DPI requires only 180 pressure data points during one engine cycle from top dead center to bottom dead center when pressure data are captured at every crank angle. Therefore, the IMEP can be estimated in real time. To further reduce the computational load, the IMEP was also estimated using DPI at 2 deg, 3 deg, and 4 deg crank angle resolutions. Furthermore, based on the estimated IMEP, we controlled IMEP using a radial basis function network and linear feedback controller. As a result of the study, successful estimation and control were demonstrated through engine experiments.

Development of IMEP Estimation and Control Algorithm Using In-Cylinder Difference Pressure for Passenger Diesel Engines

이 연구에서는 실린더 압력과 모터링 압력의 차이인 차이 압력(difference pressure)을 이용하여 IMEP 를 추정하는 방법을 제안하고, 추정된 IMEP 를 IMEP diff 로 정의하였다. IMEP diff 는 차이 압력이 연소 시작 시점에서 연소 종료 시점까지만 존재하는 압력이라는 사실에 기반하여 이론적인 IMEP 계산식의 연산 구간을 최적화한 것으로 IMEP 와 비교 시 R 2 0.9955 의 높은 선형관계를 보였다. 또한 이론적인 IMEP 계산 방법과 비교하여 21 %의 실린더 압력 데이터 및 31 %의 계산량만으로 IMEP 획득이 가능하여 실시간 제어에 용이하다. IMEP diff 추정 및 제어 성능은 엔진 실험을 통하여 검증하였으며, IMEP diff 제어를 통하여 실린더 간 토크 편차 감소를 확인하였다.In this study, we propose a new method for estimating the IMEP using difference pressure, which is the pressure difference between the cylinder pressure and the motoring pressure. The estimated IMEP, denoted as , optimizes the theoretical IMEP calculation range based on the fact that the difference pressure exists between the start and the end of combustion. is verified to have a high linear correlation with IMEP with of 0.9955. The proposed method can estimate the IMEP with 21% of the cylinder pressure data and 31% of the calculation effort compared to the theoretical IMEP calculation method, and therefore, it has great potential for real-time implementations. The estimation and control performance of is validated by engine experiments, and by controlling , the torque variation between the cylinders was reduced.

Real-Time Control of Maximum Heat Release Rate and Its Influence on Emission Dispersions in Diesel Engines

This research was financially supported by the BK21 plus program (22A20130000045) under the Ministry of Education in Republic of Korea along with the National Research Foundation of Korea (NRF) grant funded by the Korean government (MEST) (No. 2011-0017495). In addition, the research was financially supported by the Industrial Strategic Technology Development Programs (Nos. 10039673 and 10042633) of the Ministry of Knowledge Economy. Finally, this work was supported through the Energy Resource R&D Program (2006ETR11P091C) under the Ministry of Knowledge Economy in Republic of Korea.

An Alternative Method to MFB50 for Combustion Phase Detection and Control in Common Rail Diesel Engines

Although injection timing does not change at every cycle in compression ignition engines, the variations in combustion phase may occur. The variations in combustion phase are directly related to emission dispersion, torque variation, and fuel economy; therefore, the variations should be minimized by combustion phase detection and control. In this study, we propose a novel combustion indicator: location of 20% of initial heat release after the peak (IHRap20) that is an alternative to MFB50 to detect and control combustion phase in real time. IHRap20 is extracted from IHR, which is a simplified heat release model derived by the product of in-cylinder volume and the gradient of difference pressure between firing pressure and motoring pressure. IHRap20 is confirmed with engine experiment that it is highly correlated to MFB50 with RMSE of 0.2790° crank angle and R 2 of 0.9873 under various operating conditions such as injection timing, mass air flow, boost pressure, and rail pressure changes. In addition, IHRap20 is able to detect combustion phase in real time with fewer number of in-cylinder pressure data and computational load compared to MFB50. Furthermore, IHRap20 is more robust to in-cylinder pressure sensor noise than MFB50. Consequently, IHRap20 is promising for real-time combustion phase detection.