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In diesel engine development, the new technology is coming out to meet the stringent exhaust emission regulation. The regulation demands more eco-friendly vehicles. Euro6c demands to meet not only WLTP mode, but also RDE(Real Driving Emission). In order to satisfy RDE mode, the new technology to reduce emissions should cover all operating areas including High Load & High Speed. It is a big challenge to reduce NOx on the RDE mode and a lot of DeNOx technologies are being developed. So the new DeNOx technology is needed to cover widened operating area and strict acceleration / deacceleration. The existing LNT(Lean NOx Trap) and Urea SCR(Selective Catalytic Reduction) is necessary to meet the typical NEDC or WLTP, but the RDE mode demands the powerful DeNOx technology. Therefore, the LNT & Urea SCR on DPF was developed through this study.

A technical approach to reduce NOx and to minimize the fuel consumption caused by the DeNOx aftertreatment system was introduced. The NEDC mode test of the HMC (Hyundai Motor Company) DeNOx system was done with a Euro 5 vehicle (ETW (Equivalent Test Weight) = 1,810 kg, 143 kW, 430 N⋅m), which resulted in that the Euro 6 legislation standards were met. The NOx and HC emissions were, respectively, measured to be 0.059 g/km and 0.087 g/km with the hydrothermal-aged catalysts, and CO₂ was increased by ≺ 4%.

An external injection system was introduced to control the lean Nox trap(LNT). LNT absorbs Nox in lean condition of exhaust gas and discharges N2 by reducing Nox in rich condition. To make exhaust gas lean or rich, fuel injection into the exhaust gas is used with the engine control. There are two ways to add a reducing agent into exhaust gas. One is post injection using common rail system and the other is external injection. The external injection has prior benefit; can be controlled independently without disturbing engine control, can be adapted to various layout of exhaust system, has no oil dilution problem, and etc. In this study the effect of an external fuel injection on the control of LNT system was investigated. At first, the injection characteristic of the external injection was analyzed: flow rate and atomization characteristic was controlled by the PWM signal and the fuel pressure. Then the external injection system was introduced into NPRS(Nox PM Reduction System).

A NOx absorber and a fuel cracking catalyst were combined to investigate whether this could increase the low temperature activity of a NOx absorber system. Before engine exhausted gas tests, the activity and properties of the NOx absorbing catalyst were examined by simulated gas and temperature programmed desorption. Diesel fuel cracking catalysts were designed to maximize the hydrogen productivity. From the hexadecane reaction experiments for these catalysts, it was found that the hydrogen generation amount was significant even at 200°C. Engine bench test results with the diesel fuel cracking catalysts confirmed the improvement of NOx removal efficiency. In case of high NOx capacity with prolonged regeneration interval condition showed the best results. It reflects the importance of optimization of the NOx absorber and the pre-oxidation catalyst, the regeneration strategy.

The endurance life of an engine crankshaft is closely related to its fatigue strength, in addition to other material properties and shape parameters. Deep rolling, moreover, enhances the fatigue limit by applying compressive residual stress within the fillet radius area as a major surface hardening technique. The objective of this research is to maximize engine fatigue life through crankshaft design optimization by quantifying fatigue strength for microalloyed steels versus a Cr-Mo alloy steel, and to examine the effects of deep rolling load and rolled fillet geometry. Fatigue tests have been made with standard rotary bending test samples from both bar and forged blanks. Rig tests for actual crankshafts have been made to show how the fatigue strength correlates with different sample types. A correlation of stress distribution with bending moment was demonstrated by applying a strain gauging technique on crankshaft specimens.