• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.5
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• pp.2594-2602
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• 2014

As environmental awareness increases, regulations on exhaust gas of automobile, which is a cause of air pollution, have been strengthened. In order to meet emission regulation, automobile companies and engine manufacturers have actively developed the related technologies. Because the emission control has become severe, the systems using electronic motor or solenoid valve for high precise control are needed. For this reason, it is required not only the optimization of composition of components for improving performance and efficiency of the system but also the development of optimal design technology of electronic control system by securing the designing and manufacturing technology of the components. In this paper, it is proposed the position characteristics for electronic EGR valve module through the applied control logic and experiment results.

• 한국연소학회:학술대회논문집
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• 2001.11a
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• pp.185-192
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• 2001

In this study the characteristics of E-EGR valve developed by UNICK were analyzed and the feasibility of application to vehicles were evaluated. Smart car(3L/100km, cdi version) and engine which is small-displacement size, 0.8-liter, of diesel passenger car developed from Mercedes-Benz were used for this experiment. It was installed a 3-cylinder turbo-charged light duty diesel engine with an electronic EGR valve. After the analysis and comparison of E-EGR valve performance under test benchs, the estimation of vehicle application was executed through the EGR map and CVS-75 test result measured on the chassis dynamometer.

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.4
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• pp.93-100
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• 2009

Intake/exhaust valve timing and exhaust cam lift were changed to control the internal exhaust gas recirculation (IEGR) and combustion phase of homogeneous charge compression ignition (HCCI) engine. To measure the IEGR rate, in-cylinder gas was sampled during from intake valve close to before ignition start. The lower exhaust cam made shorter valve event than higher exhaust cam and made IEGR increase because of trapping the exhaust gas. IEGR rate was more affected by exhaust valve timing than intake valve timing and increased as exhaust valve timing advanced. In-cylinder pressure was increased near top dead center due to early close of exhaust valve. Ignition timing was more affected by intake valve timing than exhaust valve timing in case of exhaust valve lift 8.4 mm, while ignition timing was affected by both intake and exhaust valve timing in case of exhaust valve 2.5 mm. Burn duration with exhaust valve lift 2.5 mm was longer than other case due to higher IEGR rate. The fuel conversion efficiency with higher exhaust valve lift was higher than that with lower exhaust valve lift. The late exhaust and intake maximum open point (MOP) made the fuel conversion efficiency improve.

• Transactions of the Korean hydrogen and new energy society
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• v.19 no.6
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• pp.474-481
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• 2008

수소 기관에서 역화없이 고성능과 저$NO_x$를 실현시키기 위하여 밸브 타이밍 변화에 따른 흡기관 분사식 수소 기관의 성능을 파악하고 가솔린의 경우와 비교하였다. 그 결과 흡기밸브 타이밍은 역화억제와 성능향상에 큰 영향을 미치는 것을 확인하였다. 흡기밸브타이밍의 진각은 역화를 억제하며 효율과 출력을 동시에 향상된다. 비록 흡기밸브 타이밍 변화에 의해 NOx는 증가하지만, 희박영역인 출 ${\Phi}=0.5$에서 현저히 감소된다. 또한 열효율은 ${\Phi}=0.5$ 토크는 ${\Phi}=1.0$에서 가장 높게 나타난다. 흡기밸브 타이밍을 $ATDC20^{\circ}$에서 TDC로 변화시켰을 때, ${\Phi}=1.0$에서 토크는 약 28% 증가되고, ${\Phi}=0.5$에서 효율은 약 7%향상된다.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.1
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• pp.127-133
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• 2008

Since the 1960's, exhaust gas recirculation(EGR) has been used effectively in spark ignition(SI) engines to control the exhaust emissions of the oxides of nitrogen(NOx). The most important requirements for the application of EGR systems to conventional SI engines are controllable flow rate and good dynamic response. In order to evaluate the characteristics of the electronic EGR valve, a test bench which is consisted of blower, heater, air flow meter and driving unit for electronic EGR valve was set up to simulate engine operating conditions. During the tests, the valve actuation parameters were controlled and the valve lifts and flow rates were measured to infer the characteristics of EGR valve. The results confirmed the capabilities of mathematical analysis and it seems that the correction for the valve lift and potentiometer output is necessary to achieve precise control of EGR rates.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.5
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• pp.82-88
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• 2001

The EGR is needed fur one of various strategies to reduce NOx emission. But to get the proper EGR rate, the intake and exhaust system become complicated. That is a reason why we consider using the internal EGR system. The internal EGR is a system which reduces NOx by controling the residual gas fraction in cylinder by changing valve timing and valve lift of intake and exhaust. In this paper, characteristics of volumetric efficiency and residual gas fraction in cylinder were investigated for various engine speeds by changing valve timing and valve lift of intake and exhaust in the 4 stroke-cycle diesel engine. Volumetric efficiency and residual gas fraction were calculated by the method of characteristics. As the results, residual gas fraction and volumetric efficiency in cylinder by variable valve timing were visualized.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.5
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• pp.25-31
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• 2006

Controlled Auto Ignition(CAI) combustion has great potential in achieving significant increase in engine efficiency, while simultaneously reducing exhaust emissions. The process itself involves the auto ignition and subsequent simultaneous combustion of a premixed charge. In this study, NVO(Negative Valve Overlap) system was applied to a CAI engine in order to use residual gas. The fuel was injected directly to the cylinder under the high temperature condition resulting from heating the intake port to initiate CAI combustion. This paper introduced the valve timing strategy and experimental set-up. From this study, the effect of engine speed and valve timing on CAI combustion and exhaust emissions was clarified. In addition, stratified charge method was used to extend CAI operating region.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.5
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• pp.124-129
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• 2010

The direct injection (DI) diesel engine has become a prime candidate for future transportation needs because of its high thermal efficiency. However, nitrogen oxides (NOx) increase in the local high temperature regions and particulate matter (PM) increases in the diffusion flame region within diesel combustion. Therefore, the demand for developing hybrid system consist of exhaust gas recirculation (EGR) and aftertreatment system as well as diesel particulate filter (DPF) or lean NOx trap (LNT) should be applied. The variation of EGR rate due to the malfunction of EGR valve can affect not only the combustion stability of engine but also the performance of aftertreatment system. In this research, 2.0 liter 4-cylinder turbocharged diesel engine was used to investigate the combustion and emission characteristics for various operating conditions with EGR. While the fuel consumption was increased with increase of EGR rate, NOx emission was improved by maximum 90% at low speed, low load operating condition. To achieve combustion stability and reliability of aftertrearment system with minimum penalty in fuel consumption and emissions, the fault diagnosis of EGR malfunction must be employed.

• Journal of ILASS-Korea
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• v.15 no.1
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• pp.1-7
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• 2010

As world attention has focused on global warming and air pollution, high efficiency diesel engines with low $CO_2$ emissions have become more attractive. Premixed diesel engines in particular have the potential to achieve the more homogeneous mixture in the cylinder which results in lower NOx and soot emission. Early studies have shown that the operation conditions such as the EGR, intake conditions, injection conditions and compression ratio are important to reduce emissions in a PCCI (Premixed Charge Compression Ignition) engine. In this study a modified cam was employed to reduce the effective compression ratio. While opening timing of the intake valve was fixed, closing timing of the intake valve was retarded $30^{\circ}$. Although Atkinson cycle with the retarded cam leads to a low in-cylinder pressure in the compression stroke, the engine work can still be increased by advanced injection timing. On that account, we investigated the effects of various injection parameters to reduce emission and fuel consumption; as a result, lower NOx emission levels and almost same levels of fuel consumption and PM compared with those of conventional diesel engine cam timing could be achieved with the LIVC system.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.5
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• pp.528-534
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• 2011

This study analyzes thermal stress and durability fatigue on the modelling of EGR valve. In case of 10% opening at its inlet, the minimum temperature gets cool as 3 times as inlet temperature. The maximum equivalent stress becomes lowest as the value of $2.6274{\times}109$ Pa and fatigue life becomes highest as 23.657 Cycle. But the minimum temperature gets cool as 2.2 times as inlet temperature in case of 50% opening at its inlet. The equivalent stress becomes higher and fatigue life becomes lower than in case of 10% opening. In case of 100% opening at its inlet, the minimum temperature gets cool as 0.2 times as inlet temperature. The equivalent stress becomes lower and fatigue life becomes higher than in case of 50% opening. Maximum equivalent stress and total deformation are shown at the closing of EGR valve by the pressure of inflow gas. The structural analysis result of this study can be effectively utilized with the design of EGR valve by investigating prevention and durability against its damage.