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Vibration damping steel sheets (VDSS), which have sandwich structures with intermediate layers of resin, have been studied. The most important characteristics of VDSS for inner panels of automotive vehicles are the vibration damping properties, press formability and spot weldability. Vibration damping properties, which are quantified by loss factor,η, were influenced by both tanδ, which indicates damping capacity of resins, and elastic modulus of core resin. From a view point of vibration damping properties, resins with larger tanδ and relatively lower elastic modulus were favorable. Because these mechanical characteristics vary considerably with temperature, it is important to select the most suitable resin for the service temperature range. The relationship between noise reduction effect and loss factor of VDSS were also studied. It was experimentally confirmed that noise reduction effect of VDSS is proportional to the logarithm of their loss factor.

In this paper, emissions reduction technologies applied to high-speed direct injection (HSDI) diesel passenger car engines to meet the stricter exhaust emission legislation are described. To reduce smoke, the F.I.E. has been improved by using a radial-piston distributor pump which delivers fuel-injection-pressure up to 120MPa. Cooled exhaust gas re-circulation (EGR) system and increase in volume ratio of the combustion chamber has made it possible to increase EGR ratio and reduced nitrogen oxides (NOx) and smoke simultaneously. Furthermore, improvements in the oxidation catalyst activating temperature reduces PM at lower exhaust gas temperatures. As a result of applying these technologies, a clean and economical HSDI diesel engine for passenger cars, which complies with Japanese '98 exhaust emissions legislation and has better fuel economy than indirect injection (IDI) diesel engines (above 15%), has been developed.

Diesel particulate mass emissions and their corresponding size distributions have been investigated on a diesel passenger car at steady state conditions using standard filters and a cascade impactor. These tests have been carried out at two different engine operating conditions (2100 rpm, 2.7 and 13.3 kW, respectively) corresponding to low and high exhaust gas temperatures. Two diesel fuels differing in their sulfur content (150 ppm and 2500 ppm S) have been used for these investigations. The particulate size distribution after diesel oxidation catalyst was found to be affected by the sulfur content of the diesel fuel and by the exhaust gas temperature. Interpretations of these results on a mechanistic basis are given. The diesel particulate emission studies have been extended to dynamic vehicle tests.

A new state of the art DOC (Diesel Oxidation Catalyst) having superior light-off and exothermic activity for forced regeneration compared to conventional Pt base passive DOC, was investigated for LDD application. The DOC uses the latest Pt/Pd technology resulting cost effective DPF system. The newly developed DOC demonstrated improved catalytic activities from Pt only DOC in model gas or engine bench tests. In this study, DOC at early development stage showed excellent light-off activity in model gas and engine bench test compared to conventional Pt only DOC, however, it showed “extinction” phenomenon which is one of the deactivation mode while the post injection and it was observed when post injection operation was done at lower DOC inlet temperatures, e.g. below 250 C. Temperature profiles along diameter and length into DOC bed while active regeneration suggested extinction would be caused by fouling of supplied hydrocarbons derived from diesel fuel.

To apply a fuel economy performance to AT&CVT fluid for common use (hereinafter AT/CVT fluid) and manual transmission fluid, by optimizing fluid viscosity, a fundamental study was investigated. Generally, it is well known that the viscosity of polymer-added transmission fluids is gradually reduced, due to deterioration of the viscosity index improver caused by shear stress. An excessive viscosity reduction causes an operation failure or damage to the transmission. Considering above factor, the authors focused attention on the potential of a low viscosity formulation to improve fuel efficiency by reducing an internal stirring-resistance of the transmission. Also from the viewpoint of friction characteristics, the performance of a base oil was studied. Utilizing the EHL (Elast-Hydrodynamic Lubrication) tester [1] and vehicle tests, the performance of base oils was evaluated for the fluid development.

SOF and de-NOx catalysts are applied to heavy-duty diesel trucks which are regulated by European 13 mode or Japanese 13 mode cycles. Precious metal free catalysts can reduce SOF at low temperatures without increasing sulfates up to 670C. This catalyst shows little deterioration after 400 hours of high temperature engine aging. 32% PM and 47% SOF reduction is observed under 13 mode tests when the exhaust gas temperature exceeds 700C (ECE-13 mode). This precious metal free catalyst is suitable for diesel trucks, especially trucks with natural aspirating engine whose exhaust gas temperature is very high. De-NOx catalysts with a 300-500C NOx reduction temperature window are applied to the Japanese heavy-duty test cycle (Japan 13 mode). When secondary diesel fuel is added under modes 8 to 12, (secondary fuel addition only when catalyst inlet temperature is more than 300C), 19-25% NOx can be reduced with 2-4% fuel penalty.

Previously air-fuel ratio control using a λ O2 sensor had two problems which resulted from the binary output characteristics: (1) Insufficient convergence performance after A/F disturbance, resulting in worsening of emissions in transient states, and (2) A narrow A/F control range, resulting in worsening of emissions due to mean A/F shift in the front A/F. However, we have executed a paradigm shift to mean A/F control focused on the O2 storage ability of the catalyst and on the conversion characteristics, and carried out the following improvements. (1) Using a catalyst O2 storage model, we analyzed the interaction among front A/F feedback, O2 storage behavior, the rear. O2 signal, and emissions. Based on the results of this analysis, we designed an optimal O2 storage capacity (OSC) using a new catalyst with improved O2 storage ability, and verified that the first problem was resolved. (2) Previously, it was difficult to design front λ O2 control due to its strong non-linearity.

This paper describes the lap welding of Zinc-coated steel sheet using a high power continuous wave YAG laser. The well-known problem of welding the Zinc-coated sheet is related to the low boiling point of zinc compared with the melting point of steel. During lap welding, zinc coating at the interface vaporize rapidly and causes defects1)2). In this study, therefore, lap welding was performed by YAG laser. The effects of type of coating layer, welding conditions, tensile strength and corrosion resistance after electro-deposition was examined. It was found that the weldability of coated steel is different by type of coating. Zn-Ni coated steel showed good weldability, but galvanealed steel inevitably pore pits with no gap set up. These defects not only lower the strength of joint, but also produce irregular bead where easily corroded after electro-deposition.

The exhaust emissions of two stroke vehicles like motorbikes and scooters contribute to the pollution in urban areas of developing countries in South East Asia and India to a major extent. But also in Japan and selected European countries exhaust gas limitations become effective from 10/1998 and 06/1999 for these vehicles. To control this emissions catalytic aftertreatment by Hot Tubes® and/or monolith type catalysts are applied. Due to the constant rich operation of the two-stroke engines, common design criteria for three-way catalysts fail. Extremely high exhaust gas hydrocarbon concentrations lead to high exotherms during oxidation which increases the exhaust gas temperature to a range between 800 and 900 °C. Furthermore the lack of oxygen limits the CO and HC oxidation under certain engine operation conditions. Therefore, water-gas shift and steam reforming reactions play an important part in catalytic aftertreatment of two-stroke exhausts.

For fuel economy improvement by lean-burn gasoline engines, extension of their lean operation range to higher loads is desirable as more fuel is consumed during acceleration. Urgently needed therefore is development of emission control systems having as high NOx conversion efficiency as three-way catalysts (TWC) even with more frequent lean operation. The authors conducted a study using catalysts loaded with potassium (K) as the only NOx trapping agent in an emission control system of a lean-burn gasoline engine.

A new single-brick Ba + alkali metals NOx-Trap catalyst has been developed to replace a two-brick NOx-Trap system containing a downstream three-way catalyst. Major development efforts include: 1) platinum group metals selection for higher HC oxidation with potassium-containing washcoat, 2) alumina and ceria selection, and Rh architecture design for more efficient NOx reduction and 3) NiO to suppress H2S odor. Mitsubishi Motors' 1.8L GDI™ with this Delphi new NOx-Trap catalyst with H2S control achieves J-LEV standard with less cost and lower backpressure compared to the previous model. It is further discovered that incorporation of NiO into the NOx-Trap washcoat is effective for H2S control during sulfur purge but has a negative impact on thermal durability and sulfur resistance. Further study to improve this trade-off has been made and preliminary results of an advanced washcoat design are presented in this paper. Details will be reported in a future publication.

The purpose of this study is to explain the characteristics of homogeneous charge compression ignition. n-Heptane, which has the same cetane number as diesel fuel, was chosen for the fuel. A rapid compression machine was used to clarify the effects of air-fuel ratio, O2 concentration, and compression temperature on ignition delay and NOx emission. These investigations allowed the introduction of a formula for ignition delay.

With society demanding automobiles that provide higher fuel efficiency, safety of occupants in collisions and that at the end of their service life can be recycled with low environmental impact, the steel industry is tackling the needs of the automobile industry by developing ever-higher performance steel materials and simulation technologies that can demonstrate the performance of steel materials at the development stage without the need for costly prototype testing. In this paper, weight reduction of automobile body in Japan will be discussed. The main items will be as follows: (1) Development of Automobile Steel Sheets, (2) Materials for Automobile Bodies, (3) Materials and Technologies (Tailored Blanks, Hydroforming and Locally Quenching) for Reducing the Weight of Panels and Reinforcing members, (4) Future Prospects.

Extensive research and development has been performed to develop the NOx-adsorber catalytic system, which would make Mitsubishi vehicles powered by the gasoline direct-injection (GDI™) engines comply with European Stage 4 emissions regulations. This NOx-adsorber catalytic system is a three-brick configuration, consisting of a three-way catalyst in the front (the front catalyst) and the rear catalytic converter, composed of a new NOx-adsorber catalyst and a conventional three-way catalyst (TWC). In the present research work, a special effort has been made to define the required performance of the front catalyst, particularly with HC reduction efficiency at the cold start, the steady-state leaner A/F and the transient phase of the A/F from leaner to stoichiometric. For HC reduction, it has been found that platinum (Pt) had the highest HC efficiency.

NOx adsorber has already been used for the after-treatment system of series production vehicle installed with a lean burn or direct injection engine [1,2,3]. In order to improve NOx adsorbability at high temperatures, many researchers have recently been trying an addition of potassium (K) as well as other conventional NOx adsorbents. Potassium, however, reacts easily with the cordierite honeycomb substrate at high temperatures, and not only causes a loss in NOx adsorbability but also damages the substrate. Three new technologies have been proposed in consideration of the above circumstances. First, a new concept of K-capture is applied in washcoat design, mixed with zeolite, to improve thermal stability of K and to keep high NOx conversion efficiency, under high temperatures, of NOx adsorber catalyst. Second, another new technology, pre-coating silica over the boundary of a substrate and washcoat, is proposed to prevent the reaction between potassium and cordierite.

A method of fatigue life prediction of spot welded joint under multi-axial loads has been developed by fatigue life estimation working groups in the committee on fatigue strength and structural reliability of JSAE. This method is based on the concept of nominal structural stress ( σ ns) proposed by Radaj and Rupp, and improved so that D value is not involved in stress calculation. The result of fatigue life estimation of actual vehicle with nominal structural stress which was calculated through newly developed method had very good correlation with the result of multi-axial loads fatigue test carried out with test piece including high strength steel.

Galvannealed steel sheet (GA) is very extensively used for vehicle panels. However ζ-phase (FeZn13) in GA coat causes poor stamping formability. Previously, there were no easy methods to evaluate the influence of ζ-phase on the frictional characteristics other than the X-ray diffraction method. This study will discuss the development of a new testing method: Dr. STAMP Method that is both efficient and convenient with pin-on-disc tester.

New 440MPa class high-strength steel, which had high r-value(1.6) and elongation(38%), was applied to outer-panel for the first time in the world. In this development FEM simulation was carried out to clarify the necessary steel properties, and the production conditions in strip mill were established. 10-kg weight reduction was realized by using this steel.

Tensile testing technique for the small sample was newly developed. Small tensile specimens with gage length of 1mm were taken from spot welds of high tensile strength steel sheets, and stress-strain relationships and ductility of base metal, heat affected zone including corona bond and nugget were individually measured. Finite element analyses of spot-welded joints under the conditions of static and dynamic tensile-shear loading were carried out with these local mechanical properties to predict the fracture mode and strength of the joints. It was clarified that the effects of both nugget diameter and class of steels were evaluated with good accuracy.

In this paper the fatigue life of welded steel sheet structures is predicted by using FE-Fatigue, which is one of fatigue analysis software tools on the market, and these predicted results are evaluated by reference to corresponding experimental results. Also, we try to predict these structures by using two fatigue life prediction theories established by the JSAE fatigue and reliability committee to compare prediction results. It was confirmed that spot welds fatigue life predictions agree qualitatively with corresponding experimental results and arc welds fatigue life predictions are in good agreement with corresponding experimental results in cases where the SN curve database is modified appropriately.