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This session covers topics regarding new CI and SI engines and components. This includes analytical, experimental, and computational studies covering hardware development as well as design and analysis techniques. Presenter Sung Hoon Lee, Hyundai Motor Co.

Axiomatic design is utilized to identify the design characteristics of an On-Line Electric Vehicle and to manage the design information. The On-Line Electric Vehicle, which is being developed at the Korea Advanced Institute of Science and Technology, is a different concept of an electric vehicle from conventional electric vehicles which use the electric power of a charged battery(s). It is operated by an electric power supplied by the contactless power transmission technique between the roadway side and the vehicle. In other words, the power is transmitted based on the principle of an electric transformer. The On-Line Electric Vehicle can overcome the limitations of conventional electric vehicles such as the weight of the battery and driving distance problems. Because designers have little experience and knowledge about the On-Line Electric Vehicle in the developmental stage, an appropriate design guide is needed. The axiomatic approach is employed for the design process.

The combustion and exhaust emission characteristics of a DME fueled HCCI engine were investigated. Different fuel injection strategies were tested under various injection quantities and timings with exhaust gas recirculation (EGR). The combustion phase in HCCI was changed by an in-cylinder direct injection and EGR, due to changes in the in-cylinder temperature and mixture homogeneity. The gross indicated mean effective pressure (IMEPgross) increased and the hydrocarbon (HC) and carbon monoxide (CO) emissions decreased as the equivalence ratio was augmented. The IMEPgross with direct injection was greater than with the port injection due to retarded ignition timing resulting from latent heat of direct injected DME fuel. It was because that most of burn duration was completed before top dead center owing to higher ignitability for DME with high cetane number. However, HC and CO emissions were similar for both injection locations.

The spray characteristics of a swirl injector for direct-injection spark-ignition (DISI) engines were investigated for the generation of robust and well-atomized swirl spray. A highly-inclined tapered nozzle is applied as a test nozzle and the spray characteristics are compared with conventional nozzle and L-step nozzle. When the taper angle is 70°, an opened hollow cone spray is formed. This spray does not collapse with increasing fuel temperature and back pressure conditions. However, the taper angle should be optimized to avoid forming a locally rich area and to increase the spray volume. The droplet size of 70° tapered nozzle spray shows a value similar to that of the original swirl spray in the horizontal mainstream while it shows an increased value in the vertical mainstream. The deteriorated atomization characteristics of the tapered nozzle spray are improved by applying high fuel temperature injection without causing spray collapse.

The combustion, knock characteristics and exhaust emissions in an engine were investigated under homogeneous charge compression ignition operation fueled with liquefied petroleum gas with regard to variable valve timing and the addition of di-methyl ether. Liquefied petroleum gas was injected at an intake port as the main fuel in a liquid phase using a liquefied injection system, while a small amount of di-methyl ether was also injected directly into the cylinder during the intake stroke as an ignition promoter. Different intake valve timings and fuel injection amount were tested in order to identify their effects on exhaust emissions, combustion and knock characteristics. The optimal intake valve open timing for the maximum indicated mean effective pressure was retarded as the λTOTAL was decreased. The start of combustion was affected by the intake valve open timing and the mixture strength (λTOTAL) due to the volumetric efficiency and latent heat of vaporization.

In order to investigate the characteristics of top ring groove deposit formation in gasoline and diesel engine, engine test and simulation test were performed. From component analysis of used oils sampled from actual running engines, oxidation and nitration for gasoline engine and soot content for diesel engine were selected as main parameters for evaluating oil degradation. In gasoline engine, deposit formation increases linearly with oxidation and nitration, and especially, oil oxidation is a dominant factor on the deposit formation rather than nitration. And, deposit formation increases gradually in low temperature ranges below 260°C even if oils are highly oxidized, but it increases rapidly if piston top ring groove temperature is above 260°C. In diesel engine, deposit formation is highly related to soot content in lubricating oils.

In order to understand the relationship between the location of piston ring gap and instantaneous change of oil consumption during engine operation, the ring rotation and instantaneous oil consumption were measured simultaneously in a hydrogen fueled single cylinder spark ignition engine. A radioactive-tracer technique was used to measure the rotational movement of piston ring. Two kinds of isotopes(60Co and 192Ir) with different energy level were mounted to the top and 2nd rings to measure each ring's movement independently. The instantaneous oil consumption was obtained by analyzing CO2 concentration in exhaust gas. From the result of ring rotational movement, typical patterns of ring rotation were obtained as follows; Rotational movements are usually initiated by changing the operating conditions. Piston rings tend to rotate easily under low load condition. The rotation speed of ring usually ranged in 0.2∼0.4 rev/min for top ring and 0.5∼0.6 rev/min for 2nd ring.

Dimethyl ether (DME) as a high cetane number fuel and liquefied petroleum gas (LPG) as a high octane number fuel were supplied together to evaluate the controllability of combustion phase and improvement of power and exhaust emission in homogeneous charge compression ignition (HCCI) engine. Each fuel was injected at the intake port and in the cylinder separately during the same cycle, i.e., DME in the cylinder and LPG at the intake port, or vice versa. Direct injection timing was varied from 200 to 340 crank angle degree (CAD) while port injection timing was fixed at 20 CAD. In general, the experimental results showed that DME direct injection with LPG port injection was the better way to increase the IMEP and reduce emissions. The direct injection timing of high cetane number fuel was important to control the auto-ignition timing because the auto-ignition was occurred at proper area, where the air and high cetane number fuel were well mixed.

In this paper, a nonlinear dynamic engine model is introduced, which is developed to represent an SI engine over a wide range of operating conditions. The model includes intake manifold dynamics, fuel film dynamics, and engine rotational dynamics with transport delays inherent in the four-stroke engine cycles, and can be used for designing engine controllers. The model is validated with engine-dynamometer experimental data. The accuracy of the model is evaluated by the comparison of the simulated and the measured data obtained from a 2.0 L inline four-cylinder engine over wide operating ranges. The test data are obtained from 42 operating conditions of the engine. The speed range is from 1500 (rpm) to 4000 (rpm), and the load range is from 0.4 (bar) to WOT. The results show that the simulation data from the model and the measured data during the engine test are in good agreement.

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.

Diesel fuel injection system is the most important part of the direct-injection diesel engine and, in recent years, it has become one of the critical technologies for emission control with the help of electronically controlled fuel injection. Common rail injection system has great flexibility in injection timing, pressure and multi-injections. Many studies and applications have reported the advantages of using common rail system to meet the strict emission regulation and to improve engine performance for diesel engines. The main objective of this study is to investigate the effect of pilot-, post- and multiple-fuel injection strategies on engine performance and emissions. The study was carried out on a single cylinder optical direct injection diesel engine equipped with a high pressure common rail fuel injection system. Spray and combustion evolutions were visualized through a high speed charge-coupled device (CCD) camera.

This paper presents a conditional misfire monitoring method to reduce the computing burden of the motoring. In this conditional monitoring method, the ECU performs misfire detection only when there is high probability of misfire events. The condition for performing the misfire detection is determined by the pre-index which is defined as the deviation of the segment durations of the crankshaft in this paper. The quantity of the code of calculating the pre-index is 7 times less than that of a conventional monitoring method so that the computing burden can be reduced with the conditional monitoring method. The experimental results shown that the pre-index and the conditional monitoring method are valid.

Exhaust gas recirculation (EGR) and lean burn utilize the diluents into the engine cylinder to control combustion leading to enhanced fuel economy and reduced emissions. However, the occurrence of excessive cyclic variation with high diluent rates, brings about an undesirable combustion instability within the engine cylinder resulting in the deterioration of both engine performance and emissions. Proper stratification of mixture and diluents could improve the combustion stability under high diluent environment. EGR stratification within the cylinder was made by adopting a fast-response solenoid valve in the midst of EGR line and controlling its timing and duty. With EGR in both homogeneous mode and stratified mode, in-cylinder pressure and emissions were measured. The thermodynamic heat release analysis showed that the burning duration was decreased in case of stratified EGR. It was found that the stratification of EGR hardly affected the emissions.

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.

In order to reduce hydrocarbon emission in gasoline engine, especially during warming-up period, it is necessary to estimate the fuel and fuel product flow rate in the emission gas. The intake airflow rate should also be estimated. A strategy was proposed to estimate air fuel ratio in a spark ignition engine. The mass of air in the cylinder was determined by filling-emptying method, and the fuel in the intake manifold and cylinder was estimated by the “wall-wetting” effect calculation. The use of graphical dynamic system control software is becoming more popular as automotive engineers strive to reduce the time to develop new control systems. The rapid prototype engine controller has been developed by using MATLAB, SIMULINK, REAL TIME WORKSHOP, xPC Target, and WATCOM C++. The sensor data from the engine will be transferred to computer, and the fuel delivery will be calculated.

To meet stringent emission standards, a considerable amount of development work is necessary to ensure suitable efficiency and durability of catalyst systems. The main challenge is to reduce the engine cold-start emissions. Close-coupled catalyst (CCC) provides fast light-off time by utilizing the energy in the exhaust gas. However, if some malfunction occurred during engine operation and the catalyst temperature exceeds 1050°C, the catalytic converter becomes deactivated and shows poor conversion efficiency. Close-coupled catalyst temperature was investigated under various engine operating conditions. All of the experiments were conducted with a 1.0L SI engine at 1500-4000 rpm. The engine was operated at no load to full load conditions. Exhaust gas temperature and catalyst temperature were measured as a function of lambda value (0.8-1.2), ignition timing (BTDC 30°-ATDC 30°) and misfire rates (0-28%).

Combustion and flame propagation characteristics of the liquid phase LPG injection (LPLI) engine were investigated in a single cylinder optical engine. Lean burn operation is needed to reduce thermal stress of exhaust manifold and engine knock in a heavy duty LPG engine. An LPLI system has advantages on lean operation. Optimized engine design parameters such as swirl, injection timing and piston geometry can improve lean burn performance with LPLI system. In this study, the effects of piston geometry along with injection timing and swirl ratio on flame propagation characteristics were investigated. A series of bottom-view flame images were taken from direct visualization using a UV intensified high-speed CCD camera. Concepts of flame area speed, in addition to flame propagation patterns and thermodynamic heat release analysis, was introduced to analyze the flame propagation characteristics.

Since many electric and electronic systems are continuously added in a vehicle to meet various regulations and customer demands over the last decade, the demand on the electric power have been substantially increased. Furthermore the idle time fraction during the vehicle traveling has been increased due to the heavy urban traffic condition. The electric power system of the modern vehicle has to supply enough electrical energy to numerous electrical and electronic systems. A detailed understanding of the characteristics of the electric power system, electrical load demands, and driving environment such as road, season, and vehicle weight are required when the capacities of generator and battery are determined for a vehicle. In order to avoid an over or under design problem of the electric power system, a simulation program for electric power estimation is adequate.

Dimethyl Ether (DME) has been considered as one of the most attractive alternative fuels for compression ignition engine. Its main advantage in compression-ignition engine application is high efficiency of diesel cycle with soot free combustion though conventional fuel injection system has to be modified due to the intrinsic properties of the DME. Experimental study of the DME and conventional diesel spray employing a common-rail type fuel injection system with a sac type injector was performed in a constant volume vessel pressurized by nitrogen gas. A CCD camera was employed to capture time series of spray images, so that spray cone angles and penetrations of the DME spray were characterized and compared with those of diesel. Intermittent hesitating DME spray appeared at injection pressures of 25MPa and 40MPa in both atmospheric and 3MPa chamber pressures.