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In order to extend the operability limit of the gasoline compression ignition (GCI) engine, as an avenue for low temperature combustion (LTC) regime, the effects of parametric variations of engine operating conditions on the performance of six-stroke GCI (6S-GCI) engine cycle are numerically investigated, using an in-house 3D CFD code coupled with high-fidelity physical sub-models along with the Chemkin library. The combustion and emissions were calculated using a skeletal chemical kinetics mechanism for a 14-component gasoline surrogate fuel. Authors’ previous study highlighted the effects of the variation of injection timing and split ratio on the overall performance of 6S-GCI engine and the unique mixing-controlled burning mode of the charge mixtures during the two additional strokes. As a continuing effort, the present study details the parametric studies of initial gas temperature, boost pressure, fuel injection pressure, compression ratio, and EGR ratio.

The series-parallel hybrid electric vehicle(HEV), which employs a planetary gear set to combine one internal combustion engine(ICE) and two electric motors(EMs), can take advantages of both series and parallel hybrid system. The efficient powertrain operating point of the system can be obtained by the instantaneous optimization of equivalent fuel consumption. However, heavy computational requirements and variable constraints of the optimization process make it difficult to build real-time control strategy. To overcome the difficulty, this study suggests the control strategy which divides the optimization process into 2 stages. In the first stage, a target of charge/discharge power is determined based on equivalent fuel consumption, then in the second stage, an engine operating point is determined taking power transfer efficiency into account.

In this study, a series of tests have been carried out to evaluate the effects of the injection rate and timing on bsfc, NOx, and PM emissions in a heavy-duty diesel engine with TICS FIE system. Injection line pressure, cylinder pressure, NOx and smoke were measured with various injection times and injection rates. The injection rate was altered at a fixed injection timing, which could be realized either by changing the TICS setting time or by using different cam profiles. The injection time was varied by using TICS timing control function at a given setting time. A parametric study of the injection rate in in-line pump system was tried to correlate injection rate variations with combustion characteristics and emission. Two parameters, the injection pressure rising rate and the initially injected fuel quantity were introduced to characterize fuel injection.

In a multi-cylinder variable valve lift (VVL) engine, in spite of its high efficiency and low emission performance, operation of the variable valve lift brings about not only variation of the air-fuel ratio at the exhaust manifold, but also individual cylinder air-fuel ratio maldistribution. In this study, in order to reduce the air-fuel ratio variation and maldistribution, we propose an individual cylinder air-fuel ratio estimation algorithm for individual cylinder air-fuel ratio control. For the purpose of the individual cylinder air-fuel ratio estimation, air charging dynamics are modeled according to valve lift conditions. In addition, based on the air charging model, individual cylinder air-fuel ratios are estimated by multi-rate sampling from single universal exhaust gas oxygen (UEGO) sensor located on the exhaust manifold. Estimation results are validated with a one-dimensional engine simulation tool.

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%.

Urea-SCR system consisted of combined deNOx catalysts with wide range of temperature window, injector, sensor and injection controller. Synthetic gas activity test and NOx conversion efficiency test on the engine bench were carried out to evaluate and improve the performance of this system. To better suit the application of the urea-SCR system without engine modification, temperature of catalyst and engine RPM were used as input data to control amounts of urea aqueous solution that reacts with NOx. We concentrated on designing types of deNOx catalysts and controlling amounts of urea solution under different driving conditions to achieve higher NOx reduction and wider temperature window. Designed urea-SCR system showed substantial NOx reduction performance and relatively wide temperature window under different driving conditions.

As CO2 emissions from vehicles is gaining a global attention the low fuel consuming power-train is in much greater demand than before. Some alternatives are suggested but the HSDI diesel engine would be the most realistic solution. Vehicle simulation shows that low fuel consuming car can be realized by applying 1∼1.2L HSDI diesel engine in vehicles weighing about 750kg. While the direct injection diesel engine has been researched for a long time enhancement of mixing between air and fuel in a limited space makes it challenging area to develop a small swept volume HSDI diesel engine. We are investigating small HSDI diesel engine combustion technologies as an effort to realize low fuel consuming vehicle. Our main objective in this study is to have a better understanding of the combustion related parameters from such a small size HSDI diesel engine in order to improve engine performance.

Emission of carbon dioxide from mobile sources seriously concerned to solve greenhouse effect and high price of gasoline in some countries have resulted in the development of lean-burn concept engine. In spite of many studies on the lean deNOx catalyst, we have no clear solution to obtain high fuel economy and high efficiency of NOx conversion in lean-burn application. This paper describes applicability and problems of NOx adsorber system to partial lean-burn vehicle, the development of three-way catalyst with improvement of washcoat technology based on three-way catalyst used for gasoline application, and comparison test results of evaluations is synthesized gas activity test, Federal Test Procedure (FTP) test, etc. This study shows improved three-way catalysts in partial lean- burn vehicle have max. 89% of NOx conversion in FTP without adding rich spike and regeneration functions to engine management system.

This study suggests new types of catalysts that show low hydrogen sulfide emission without scavenger such as NiO. Hydrogen sulfide can be reduced by changing the physicochemical properties of washcoat components. Synthesized gas activity tests were performed to investigate the effect of modified washcoat on hydrogen sulfide formation and catalytic activity. BET surface area tests, X- ray diffraction tests, and gas chromatography tests were also carried out to examine the characteristics of catalysts. Preparation methods for catalysts were focused on minimizing the adsorption of sulfur species on catalysts. The first approach is heat treatment of cerium oxide to reduce adsorption sites for sulfur compounds. But this leads to deterioration of CO and NOx conversion efficiencies. The second one is adding new types of promoters that increase thermal durability and dynamic oxygen storing function of cerium oxide.

This paper describes the development of THC reduction technologies compliant with SULEV regulations. Technologies embodied by the developmental work include improvement of fuel spay atomization, quick warm-up through coolant control shut off, and acceleration of fuel atomization for the fast rise of cylinder head temp inside the water jacket as well as the improvement of combustion state. The technologies likewise entail reduced HC while operating in lean A/F condition during engine warm-up with the cold lean-burn technology, individual cylinder A/F control for improvement of catalytic converting efficiency, aftertreatment such as thin-wall catalyst, HC absorber and EHC and etc., through vehicle application evaluation in cold start. We carried out an experimental as well as a practical study against SULEV regulations, and the feasibility of adopting these items in vehicle was likewise investigated.

The new concept oxidation for diesel engine has been developed. It has been designed to use under circumstances of the "dry condition" of exhausted emission, which indicates low soluble organics and high dry soot concentration under high exhaust gas temperature. For the reliability and performance of catalysts in dry condition, several design concepts were established. First of all, extremely low sulfate formation on catalyst at high temperature conditions, and an improved soluble organic burning characteristics was required. A minimization of deposition of the particulate component, especially sulfate, was obtained from the adjustment of washcoat loading and material property. Six different types of catalysts have been prepared and tested in a laboratory. Diesel vehicle test showed the possibility that soluble organic could be removed mostly with minimal sulfate formation.

High pressure fuel injection systems, such as common rail (CR) systems and electronically-controlled unit injector (EUI) systems, have been widely applied to modern heavy duty diesel engines. They are shown to be very effective for achieving high power density with high fuel efficiency and low exhaust gas emissions. However, the increased peak combustion pressure gives additional structural stress and thermal load to engine structure. Thus, proper material selection and thermal analysis of engine components are essential in order to meet the durability requirements of heavy-duty diesel engines adopting a high pressure injection system. In this paper, thermal analysis of a 12.9 ℓ diesel engine with an EUI system was studied. Temperatures were measured on a cylinder head, a piston and a cylinder liner. A specially designed linkage system was used to measure the piston temperatures. A radio-tracer technique was also used to verify the rotation of piston rings.

Currently, diesel engine-out exhaust NOx emission level prediction is a major challenge for complying with the stricter emission legislation and for control purpose of the after-treatment system. Most of the NOx prediction research is based on the Zeldovich thermal mechanism, which is reasonable from the physical point of view and for its simplicity. Nevertheless, there are some predictable range limitations, such as low temperature with high EGR rate operating conditions or high temperature with low EGR rates. In the present paper, 3 additional considerations, pilot burned gas mixing before the main injection; major NO formation area; concentration correction, were applied to the previously developed real-time NO estimation model based on in-cylinder pressure and data available from ECU. The model improvement was verified on a 1.6 liter EURO5 diesel engine in both steady and transient operation.

A comprehensive investigation was carried out in order to develop the idle sound quality for diesel V6 engine when the engine development process is applied to power-train system, which included new 8-speed automatic transmission for breaking down the noise contribution between the mechanical excitation and the combustion excitation. First of all, the improvement of dynamic characteristic can be achieved during the early stages of the engine development process using experimental modal analysis (EMA) & the robust design of each engine functional system. In addition, the engine structural attenuation (SA) is enhanced such that the radiated combustion noise of the engine can be maintained at a target level even with an increased combustion excitation. It was found that the engine system has better parts and worse parts in frequency range throughout the SA analysis. It is important that weak points in the system should be optimized.

Engine calibration on the powertrain test bed with transient mode is proposed with dynamic powertrain test bed having low inertia dynamometer. Automated ECU (Engine Control Unit) calibration system is completed with the combination of experimental design software, powertrain test bed, evaluation tools and their electrical interfaces. The process is composed up of the system interface definition, test design using DoE skill, test proceedings by step sequence of connecting systems, measured data collecting, mathematical model and optimization result extraction at the end. All the processes are automated by interfaces between the systems. Acceleration surge is minimized by proposed process by optimizing combustion control labels and tip in driveability is maximized by manipulating torque filter labels of EMS (Engine Management System) logic. Their detailed steps from the problem definition to the verification test results of improved design with vehicle test are presented.

In this research, an optical system for the detection of the flame propagation under the non-knocking and knocking conditions is developed and applied to a mass produced four cylinder SI engine. The normal flames are measured and analyzed under the steady state operating conditions at various engine speeds. For knocking cycles, the flame front propagations before and after knock occurrence are simultaneously taken with cylinder pressure data. In non-knocking and knocking cycles, flame propagation shows cycle-by-cycle variations, which are quite severe especially in the knocking cycles. The normal flame propagations are analyzed at various engine speeds, and show that the flame front on the exhaust valve side becomes faster as the engine speed increases. According to the statistical analysis, knock occurence location and flame propagation process after knock can be categorized into five different types.

In this study, single cylinder engines with different tumble ratio were made to show the effects of tumble motion on engine performance and flame propagation. Particle tracking velocimetry technique by using chopper was adopted to examine the in-cylinder flow field for the full understanding of tumble motion. And equivalent angular speed of tumble vortex was obtained from each crank angle and compared with tumble ratio derived from the steady state flow rig test. Flame propagation speed were obtained with the gasket ionization probe and the piston ionization probe. And the combustion pressure in cylinder was measured to analyze the combustion characteristics. In case of high tumble engine, BSFC and BSHC were decreased and BSNOx was increased at part load test, BMEP and combustion peak pressure was increased at full load test. Also, flame propagation characteristics could be understood by use of piston ionization probe.

Four ports which have slightly different shapes have been applied to 3-valve MPI SI engine to develop Axially Stratified Lean Combustion engine. The purpose of port modification test was to investigate the effects of swirl ratio and direction on engine performance and emissions. In the engine test injection characteristics, i.e. timing, flow rate, direction as well as port design significantly effected on the engine combustion. Especially, it was observed that injection timing was the most important factor for combustion stability, but its effect on performance has some differences in accordance with the port designs. To verify the relationship between port shape and injection timing, in-cylinder gas was sampled by high speed gas sampling device varing injection timing through whole intake and compression,. strokes at spark plug position and analyzed by gas chromatography.

In HMC, the fundamental research on the hydrogen fueled engine and vehicle has been carried out. For this engine, solenoid driven injector is used to supply gaseous hydrogen into the cylinder and various operating parameters have been changed to study the combustion characteristics of hydrogen. After these experiments on engine, hydrogen fueled vehicle has been constructed and it is controlled by ECU. The amount of emission from the hydrogen vehicle with stoichiometric operation is less than 1/3 of the ULEV legislation.

Today, light connecting rods are vital to satisfying the demands of modern internal combustion engines. HYUNDAI Motor Company (HMC) has applied powder metal forged connecting rods instead of conventional hot forged connecting rods to obtain low product costs and to improve NVH characteristics and bearing reliability. Light connecting rods were developed through optimized design with high quality and low cost. Notably, the mass of a powder metal forged connecting rod is 17.7% lighter than that of a conventional hot forged type connecting rod, and its crank end is 22.5 % lighter than that of a conventional type connecting rod. Light connecting rods result in reduced crankshaft mass, so the mass of the main moving parts can be reduced. With this mass reduction, bearing reliability and NVH characteristics can be enhanced.