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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.

There have been strong moves in recent years to introduce the metal matrix composites concept into higher volume applications, notably the automotive field where large volume production and lower material costs are required. The wettability between reinforcing materials and base material is one of important factors for the strength of composites and its manufacture. The main objective of this paper is to establish a basic understanding of wetting phenomena in SiC/liquid aluminum and aluminum alloy systems. In the present paper, results from the sessile drop method are reported for the effects on the wetting angle, θ, of free silicon in the silicon carbide substrate and of alloying additions of silicon, copper or magnesium to the aluminum drop for the temperature range 700-900 or 1400°C in the titanium-gettered vacuum (1.3 x 10-2 / 1.3 x 10-3 Pa).

An increasing number of cars which are being used to foster leisure and a convenient life for consumers are being outfitted with roof racks and/or cross bars. This trend of installing roof racks is partly for the function of carrying objects on the roof of the vehicle and partly as a way to affect the style and exterior look of the vehicle. Therefore, the application of roof racks and cross bars is becoming increasingly important in the automotive industry. Because of the expanding application of roof racks on vehicles, the challenge of reducing wind noise caused by exposed cross bars becomes the main issue in this field. For solving this problem, the cross bar shape is designed and evaluated in the development stage, and if there is a problem, it is re-designed and re-evaluated many times. This repetitive corrective action is called “trial and error”.

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.

Main design features and some of the development work carried out on the first new engines to be produced in-house by Hyundai Motor Co. are described. The Alpha family of multi-valve, four cylinder engines comprises 1.3 and 1.5L naturally aspirated units and a 1.5L turbocharged version. Modern features are incorporated in the engines in order to provide higher performance and good fuel economy with excellent durability at reasonable cost. Hyundai Motor Co. (HMC) was established in 1967 and, in the following year, commenced production of passenger cars for the domestic market, using CKD components supplied by Ford of Europe. In 1974 the Pony saloon car entered production; this used mainly locally produced components but most of the major items, including the power train - engine and gearbox - were manufactured under the license from Mitsubishi Motors.

An automobile's structure is generally connected by spot welding the sheets together. Sometimes more than three layers of sheets can be used in a certain location for spot welding due to the limits of design conditions. Static strength and the fatigue life characteristics can be changed according to the welding conditions, which depend on the material, the thickness, and the number of sheets. Setting the appropriate conditions of multi-layer spot welding can be determined by analyzing static strength and fatigue life. For converting multi-layer spot welding to that of twofold layer with equal strength, the converting method can be suggested from static and fatigue test results. The increasing rate of static strength is larger than that of fatigue life, so it is reasonable to use fatigue life for limit condition.

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.

A new recycled material has been developed by using the scrap of tail lamp assembly, made of poly(methyl methacrylate) (PMMA) for the lens and acrylonitrile-butadiene-styrene terpolymer (ABS) for the housing. Lamp scrap was extruded in a twin-screw extruder, and mechanical properties of the scrap were compared with ABS, PMMA, and an ABS/PMMA (60/40) blend. The recycled material from 100% tail lamp scrap has similar modulus to the 60/40 blend, however, notched Izod impact strength and thermal resistance were lower than that of the blend, probably due to the presence of hot melt adhesive and silver paint. Scrap/virgin polymer mixtures showed improved thermal resistance and impact strength. The effects of composition and type of mixed polymer on mechanical properties were also investigated.

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.

Low-pressure molding compound (LPMC) is a new kind of composite material which can be used for automotive body panels. LPMC has similar mechanical properties compared to conventional sheet molding compound (SMC) but excellent moldability due to the different thickening system. In this paper, we prepared LPMC hood prototype for a passenger car using a low-cost tooling. Inner panel and outer panel were made of general-density- and low-density-grade LPMC, respectively, in order to maximize weight reduction maintaining surface quality. Physical properties containing tensile strength, flexural modulus, notched Izod impact strength of those samples were investigated. In addition, CAE simulation was also done for strength analysis of the hood assembly.

Invisible Passenger-side Airbag (IPAB) door system must be designed with a weakened area such that the airbag will break through the Instrument Panel (IP) in the intended manner, with no flying debris at any temperature. At the same time, there must be no cracking or sharp edges at the head impact test (ECE 21.01). Needless to say, Head impact test must keep pace with the deployment test. In this paper, we suggested soft airbag door system that is integrally molded with a hard instrument panel by using Two-shot molding. First of all, we set up the design parameters of IPAB door for the optimal deployment and head impact performance by CAE analysis. And then we optimized the open-close time at each gate of the mold so that the soft and hard material could be integrally molded with the intended boundary. We could make the boundary of two materials more constant by controlling the open-close time of each gate with resin temperature sensor.

Reducing unsprung mass of the car is a representative method to enhance the ride & handling performance and fuel efficiency. In this study, brake disc weight is reduced 15∼20% using a hybrid type material. The basis for this study is the separation of the friction surface and HAT(mounting part). Aluminum material is applied in the HAT for a light weight effect. Gray iron is applied in the friction surface section to maintain braking performance. Two types of joining between aluminum and cast iron are developed. One is the aluminum casting method utilizing a gray iron insert and the other is a bolted assembly method. Detailed structure, process and material are optimized using try-out & dynamometer experiments. The Reliability of this development is proved through durability (dynamometer and vehicle) testing.

This paper presents a study on using rubber bushing as a sensor for the identification of forces transmitted onto the car body. The method starts from the idea that the transmission forces can be related to the deformation of the rubber bushing multiplied by its stiffness. Deformation of the rubber bushing is estimated from relative vibrations across the bushing. Simple theories are presented to deal with modeling of the rubber bushing and processing of the vibration mesurements on the link and car body to identify the transmission forces. Then, validity of the proposed approach is shown by applications to a suspension system under several driving conditions.

Vehicle body structures are formed by thousands of spot welds, and fatigue failure of vehicle structures occur near the spot welds after driving a long way at a durability test road. It is necessary to know accurately the reason of the fatigue failure of the spot weld in the developing stage in order to reinforce it. Many investigations have been done regarding the strength of spot welded joints, contributing to understand its fatigue strength. In the developing process, a fatigue failed spot welded area can be repaired by CO2 welding or another method to continue the test. To know the effect of reinforcing these welds, several methods of welding were analyzed and compared to spot welding. With the results of this test, the appropriate repair method can be used instead of spot welding during the development of a new car and the best design guide can be given for the strength.

End-plates are highly stiff plates that hold together the components composing a fuel cell stack, i.e. Membrane Electrode Assemblies (MEAs), Gas Distribution Layers (GDLs) and bipolar plates, offering sufficient contact pressure between them. The proper contact pressure is required not only to improve energy efficiency of a stack by decreasing ohmic loss but also to prevent leakage of fluids such as hydrogen, air, or coolant. When a fuel cell starts in cold environment, heat generated in a fuel cell stack as a result of electrochemical reactions should not be used much to increase the temperature of endplates but to melt ice inside the stack to prevent ice-blocking and to increase the temperature near the three-phase-boundary on MEAs. However, to satisfy the high stiffness required, massive metallic endplates have been used despite their inferior thermal characteristics: high thermal conductivity and large thermal inertia.

The banded microstructure of pearlite and ferrite in normalized alloy steel is susceptible to thermal distortion during carburizing process due to its unidirectional orientation parallel to rolling direction. The planetary gears with material of banded microstructure have been experienced in high thermal distortion during carburizing and quenching process and result in uneven surface hardness and effective case depth at the inside of pinion gear after honing. These defects played failure initiation site roles in durability test during development of new automatic transmission. The galling between the contacting components in severe lubricating system was the main failure mechanism. Double normalizing at 920 °C was designed to resolve the banded microstructure of normalized alloy steel. The microstructure and grain size of the double heated steel became equiaxed and fine due to homogenizing and recrystallization through double heat treatment.

We developed the hard IP (Instrument Panel) that is integrally over molded with a soft layer (TPO, Thermo Plastic Olefin) for the soft feeling and cost reduction. And also we produced the cost-effective PAB(Passenger-side Airbag) door system that had an in-mold tearseam and avoided competitors' patents simultaneously. The development procedure of this technology is; ① Material for overmolding ② Design optimization ③ Solving tool challenges. The reduction of process through integrally molding with soft material helped to accomplish a soft feeling on the IP and cost reduction at the same time. The deployment, head impact and heat aging tests were conducted and 5 patents were applied such as the optimization of the mold structure and injection condition.

A new thermoplastic polyolefin with primerless adhesion to paint has been developed by polypropylene (PP) with α-olefin copolymers, mineral fillers and some additives. It can substantially reduce costs and environmental problems by eliminating primer treating operations, traditionally treated from trichloroethene (TCE). This new material exhibits unique solid-state texture that rubbery polymer component are typically dispersed in lamellar structure matrix. Versus conventional PP or thermoplastic olefin (TPO), it provides excellent brittle-ductile (BD) transition as well as paintability. Also it is expected to have a significant impact on interior parts as requirements for material change to an emphasis on light weight, lower cost, more efficient finishing.

It is difficult to reach higher compression ratios of the gasoline engine even though higher compression ratios improve thermal efficiency. One of the barriers is large torque drop led by knocking. Extensive researches to suppress knocking of the gasoline engine have been conducted. It is focused on lowering the temperature of fuel mixture in combustion chamber at compression top dead center (TDC). This paper covers the new valvetrain system to decrease the temperature of exhaust valve bottom (combustion) side. Hollow head and stem sodium filled valve (HHSV) have shown more heat transfer from combustion chamber to valve seat insert and valve guide, and higher thermal conductivity valve seat insert (HVSI) and valve guide (HVG) help to decrease valve temperature lower by higher heat transfer.

A newly developed surface hardening process, supercarburizing, has been developed for the application of tappet shim to improve fuel economy. Supercarburizing has been introduced to increase resistance of wear and pitting performance and was designed to have supersaturated carbon surface layer and further to have spheroidized carbide morphology. In this presentation, the process variables, such as surface microstructure, morphology and distribution of carbide precipitation, will be discussed via the results of friction loss tests. At an entire speed range investigated, the application of supercarburized tappet shim improved fuel economy with 25∼30% in terms of valve train itself and with 4∼5% concerning on the gross engine performance. The fuel economy analysis showed that the improved surface hardening process of tappet shim increased fuel economy of vehicle about 1.4∼3.6%.