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Seungsuk Oh,Jaesung Chung,Myoungho Sunwoo IEEE 2015 IEEE/ASME transactions on mechatronics Vol.20 No.4
<P>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 <SUP>2</SUP> 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.</P>
디젤엔진의 실시간 연소제어를 위한 연소위상검출 알고리즘개발
오승석(Seungsuk Oh),임종석(Jongsuk Lim),정재성(Jaesung Chung),이강윤(Kangyoon Lee),선우명호(Myoungho Sunwoo),한경찬(Kyungchan Han),유준(Jun Yu),박승일(Seungil Park) 한국자동차공학회 2010 한국자동차공학회 학술대회 및 전시회 Vol.2010 No.11
In diesel engines, even if fuel is injected at identical time, combustion phase varies depending on operating conditions such as temperature, humidity, and fuel properties. Such deviations of combustion phase are directly related harmful emissions and torque performance, therefore the combustion phase needs to be detected and controlled. In this study, we propose a novel combustion detection algorithm, Difference pressure Heat release using dP term (DHdP) to detect combustion phase in real-time. DHdP is derived from the difference pressure between firing pressure and motoring pressure and detects combustion phase. DHdP shows a strong linear relationship with 50% mass fraction burned (MFB50), which is well-known for a combustion phasing indicator, under different operating conditions. Furthermore, DHdP requires fewer cylinder pressure data and lighter calculation load, so that it is suitable for real-time applications.
Development of a Combustion Phase Indicator for Real-Time Combustion Control in CRDI Diesel Engines
Jongsuk Lim,Seungsuk Oh,Jeasung Chung,Kangyoon Lee,Myoungho Sunwoo 한국자동차공학회 2010 한국자동차공학회 학술대회 및 전시회 Vol.2010 No.11
The location of 50% mass fraction burned (MFB50) is known as a good combustion phase indicator because of its close correlations with harmful emissions and fuel efficiency. Nevertheless, since calculation of MFB50 involves a large amount of cylinder pressure data and complex algorithm, it is difficult to be implemented in a real-time engine controller. For this reason, a new combustion phase indicator with a small number of cylinder pressure data and simple algorithm is demanded for real-time combustion control. In this study, we propose a new combustion phase indicator, called the location of 60% normalized difference pressure after peak (NDPap60). The NDPap60 indicates the crank angle position where the normalized difference pressure reaches 60% of the maximum value after peak. The proposed indicator reveals a linear correlation with MFB50 at various engine operating conditions such as main injection timing, injected fuel quantity, fuel-rail pressure and EGR rate changes. Furthermore, the NDPap60 requires about 55% measurement data of cylinder pressure and 18% calculation steps in comparison with the MFB50. Consequently, the NDPap60 demonstrates great potential for applying to a real-time engine controller.
Kyunghan Min,Seungsuk Oh,Minkwang Lee,Myoungho Sunwoo 한국자동차공학회 2012 한국자동차공학회 학술대회 및 전시회 Vol.2012 No.11
In diesel engines, the start of combustion (SOC) is an important engine control indicator due to its effects on to engine noise, emission, and engine performance. The SOC is calculated as a location of one percent of total heat release which can be calculated using cylinder pressure. However the calculation of heat release requires a large amount of cylinder pressure data and enormous computation time. In this study, we proposed a simplified SOC estimation algorithm using an initial heat release (IHR). The IHR is modified heat release equation which eliminates negligible terms of the heat release equation at the start phase of combustion. The IHR has the similar tendency near the combustion start range. Especially the location of two percent of the IHR has a high linear correlation with the SOC under various engine operating conditions, such as varying the fuel rail pressure, injection timing, injection quantity, boost pressure, and EGR rate. We defined the location of two percent of IHR as IHR2. Furthermore, the proposed method reduces 55% of computational load and 50% of required number of cylinder pressure data compared to one percent of heat release detection method.
디젤 엔진의 엔진 토크 제어를 위한 실시간 IMEP 추정 알고리즘 개발
정재성(Jaesung Chung),오승석(Seungsuk Oh),이민광(Minkwang Lee),선우명호(Myoungho Sunwoo) 한국자동차공학회 2011 한국자동차공학회 부문종합 학술대회 Vol.2011 No.5
The indicated mean effective pressure (IMEP) is an indicator which represents the engine torque directly from the in-cylinder pressure. However, the calculation of IMEP requires a large number of cylinder pressure data acquisition and long computation time. For this reason, an estimation method of IMEP with less number of cylinder pressure data acquisition and computation time is needed for real-time combustion control. In this study, we proposed the IMEP estimation algorithm using difference pressure. The difference pressure data during the expansion stroke is used to estimate the IMEP and defined the estimated IMEP value as IMEPdiff. The proposed IMEPdiff has high linear relationship with the real IMEP regardless of different engine operating conditions. Furthermore, the IMEPdiff method reduces the data acquisition of cylinder pressure by 75% and the computational load by 62% compared to the IMEP method which gives a great potential for the real-time estimation of IMEP.
Chung, Jaesung,Min, Kyunghan,Oh, Seungsuk,Sunwoo, Myoungho Elsevier 2016 Applied thermal engineering Vol.99 No.-
<P><B>Abstract</B></P> <P>This paper proposes an in-cylinder pressure based real-time combustion control algorithm to reduce combustion dispersions from diesel engines. The proposed algorithm manipulates main injection quantity and timing as well as pilot injection quantity to control the Indicated Mean Effective Pressure (IMEP), crank angle location where 50% of Mass Fraction Burned (MFB50) and maximum value of Rate of Heat Release (ROHR<SUB>max</SUB>). This control algorithm reduces the combustion dispersions by controlling the heat release curve for each operating condition.</P> <P>The proposed real-time combustion control structure mitigates combustion dispersions caused by operating condition changes, un-calibrated fuel injectors, and environmental condition variations, and it is validated with various experiments. In these experiments, various engine control variables were changed to validate the reduction in combustion dispersion when operating conditions change unintendedly. Changes in coolant temperature verified the compensation effect of the proposed algorithm under different external environments. It is validated with these experiments that there are 30% reduction in torque imbalances, a 10% emission dispersions reduction for NO<SUB>x</SUB> emissions, and a 65% reduction for PM emissions.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A consolidated real-time combustion control algorithm is proposed. </LI> <LI> The control algorithm reduces the dispersions of combustion caused by various reasons. </LI> <LI> This control algorithm is validated with various engine experiments. </LI> <LI> As a result, 10% of NO<SUB>x</SUB> dispersions and 65% of PM dispersions were reduced. </LI> </UL> </P>
승용 디젤 엔진의 실린더 차이 압력을 이용한 IMEP 추정 및 제어 알고리즘 개발
정재성(Jaesung Chung),오승석(Seungsuk Oh),박인석(Jaesung Chung),선우명호(Myoungho Sunwoo) 대한기계학회 2012 大韓機械學會論文集B Vol.36 No.9
이 연구에서는 실린더 압력과 모터링 압력의 차이인 차이 압력(difference pressure)을 이용하여 IMEP 를 추정하는 방법을 제안하고, 추정된 IMEP 를 IMEPdiff 로 정의하였다. IMEPdiff 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<SUP>2</SUP> 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. IMEPdiff 추정 및 제어 성능은 엔진 실험을 통하여 검증하였으며, IMEPdiff 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 IMEPdiff, optimizes the theoretical IMEP calculation range based on the fact that the difference pressure exists between the start and the end of combustion. IMEPdiff is verified to have a high linear correlation with IMEP with R<SUP>2</SUP> 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 realtime implementations. The estimation and control performance of IMEPdiff is validated by engine experiments, and by controlling IMEP<SUP>diff</SUP>, the torque variation between the cylinders was reduced.