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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.

An investigation has been performed to study the response of the front bumper beam of automobiles subjected to an external impact load. In the investigation, an aluminum shell structure is modeled as a beam, and the energy absorber of polyurethane is also modeled as statically equivalent springs attached to the beam. Castigliano's second theorem and principles of energy and momentum are then used to calculate the reaction forces and maximum deflection. Stress distribution is then calculated using the beam theory. The primary concern of the investigation is to present a procedure of how to design optimally the cross-sectional shape of the front bumper of automobiles.

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 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 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.

Air conditioning is defined as the process of treating air so as to control simultaneously its temperature, humidity, cleanliness and distribution to meet the requirements of the conditioned space. As in the definition, the important actions involved in the operation of an air conditioning system are temperature and humidity control, air purification and movement. For these conditions this paper proposes a Automatic Climate Control(ACC) system of the bus. The system has cooling, heating, and dehumidifying modes, and is governed by dual 8-bit microprocessors. These modes are broken down into sub-modules dealing with control of the compressor, blower speed, damper position, air purifier, ventilators, preheater, air mixing damper and so on.

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.

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.

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.

Ground systems in automobiles become more important as more electric devices are installed and the amount of currents flowing increases. The performance of the devices depends on the ground voltage, which is generated between ground points by I-R voltage drops. Therefore, low ground voltages are required for the reduction of the unnecessary power dissipation as well as the reliable performance of the devices. In this paper, we propose an automotive ground system model to analyze ground structure and reveal the main cause of ground voltages. The equivalent resistor network model is presented to describe the relationship between ground points. Then, we validate the model by comparing the simulation results with the measurements in a real car. The presented analysis can provide guidance on designing a reliable ground system such as how to reduce the ground voltages for the proper operation of devices.

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.

Fuel tank in vehicle must hold the fuel in a stable way under any driving condition. However, the fuel tank might not conserve the fuel firmly in case a crack emerged while the fuel tank is exposed to different driving condition. Basically, when the engine is in purging at a normal ambient temperature before fuel boiling, the pressure inside the fuel tank decreases. However, the pressure inside a fuel tank increases while a vehicle is driven at extreme hot ambient temperature as fuel is boiling. This repetitive pressure change in the fuel tank comes with fuel tank’s physical expansion and shrink, which would cause a damage to the fuel tank. The main purpose of this research is to investigate the root cause of why fuel tank cracks at a fatigue point. We also aim to set up the method of how to test durability of the fuel tank in association with the pressure inside the tank.

Voice Recognition (VR) systems have become an integral part of the infotainment systems in the current automotive industry. However, its recognition rate is impacted by external factors such as vehicle cabin noise, road noise, and internal factors which are a function of the voice engine in the system itself. This paper analyzes the VR performance under the effect of two external factors, vehicle cabin noise and the speakers’ speech patterns based on gender. It also compares performance of mid-level sedans from different manufacturers.

A nano-sized PM and THC emission characteristics were investigated according to the fuel injection strategy such as a pressure and timing in the GDI engine. On the part-load condition, the particulate emissions exhibited a strong sensitivity to the injection timing. The fuel injection pressure also had a great association with the nano-particles and THC. A size of PM exhausted from the GDI engine located near 10nm on the part-load. In contrast, accumulation mode particles within 60 - 80nm mainly exhausted during the cold transient start phase. Increment of fuel injection pressure positively affected on the nano-particle and THC emissions during the start of the engine, as well.

In this paper, an active type variable intake system is proposed, which improves both engine power and NVH performance. The proposed system uses a magnet valve to control the air path to the engine intake manifold. While other types of variable intake system such as vacuum actuator type or DC motor type need an ECU to control the valve, the proposed system only uses force equilibrium between magnetic force and vacuum pressure, resulting in weight and cost reduction. The system is composed of dual duct (duct A, duct B) and a magnet valve. In low RPM region, the magnet valve is closed and only duct A is used to supply air into the engine. In high RPM region the valve opens up and maximizes the amount of the air that goes into the engine intake manifold. The result is that the output power of the engine is maximized in high RPM region, as well as the NVH performance is improved in low RPM region.

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.

Recently, flexible fuel vehicle (FFV) has been drawn great attention because of its response for immediate use as alternative fueled one. Hyundai FFV can be operated on arbitrary fuel mixtures between gasoline and M85 with the specially programmed electronic control unit (ECU) which can determine optimized fueling quantity and ignition timing as the methanol content by the signal from electrostatic type fuel sensor. In this paper, the results of various tests including engine performance, cold startability, durability and exhaust emission reduction have been described. Full load, cold mode durability tests and field trials have been carried out with some material changes and surface treatments in the lubricating parts and fuel system. But, more work on its durability improvement is still required.

This paper describes Hyundai's research and development work on a flexible fuel vehicle (FFV). The work on FFV has been conducted to evaluate its potential as an alternative to the conventional gasoline vehicle. Hyundai FFV described here can operate on M85, gasoline, or any of their combinations, in which the methanol concentration is measured by an electrostatic type fuel sensor. For that operation, a special FFV ECU has been developed and incorporated in the FFV. The characteristics affecting FFV operation, such as FFV ECU control strategy and injector flow rate, have been investigated and optimized by experiment. Various development tests have been performed in view of engine performance, durability, cold startability, and exhaust emissions reduction. The exhaust gas aftertreatment system being consisted of manifold type catalytic converter(MCC) and secondary air injection system has shown good emission reduction performance including formaldehyde emission.

This paper shows the cause and the solution to the uncommon noise which happens ½ order component of engine rpm when a vehicle with automatic transmission has an air conditioning load and “drive” range load on the engine. By measuring cylinder pressure, main bearing cap vibration, engine mount vibration, and interior noise simultaneously, the cause of the noise can be proved by analyzing and comparing the data. The cause of the uncommon noise is bending vibration of the crank shaft. To solve the problem, one can change the crank shaft dynamics by reducing the mass of the damper pulley.