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A multi-dimensional numerical method for predicting the warm-up characteristic of automobile catalytic converter systems was developed to effectively design catalytic converter systems which achieve low tail pipe emissions with satisfactory packagebility. The features of the method are; (1) consideration of the governing phenomena such as gas flow, heat transfer, and chemical reactions (2) capability of predicting warm-up characteristic for not only the catalytic converters but also the system as a whole during emission test modes such as the USA LA-4 mode. The description of the method is presented. The experimental verifications of the method were conducted to assure the accuracy of it. The effect of design parameters such as electrically heated catalyst (EHC), high loading of noble metal and thin honeycomb wall on warm-up characteristic of the catalyst are analyzed in the paper.

A new test machine has been developed which can evaluate vibration due to stick-slip using an actual full-scale clutch pack. Using this machine, a static breakaway friction coefficient measurement test method and a stick-slip test method have been established. Both methods have been shown to provide results which correlate with the results from both a full-scale assembly test and a vehicle shudder evaluation test. The evaluation of the frictional properties of commercial oils using these test methods showed that the static breakaway friction coefficient and the stick-slip properties have generally contradictory performance to each other for automatic transmission. The study of the frictional properties for typical additives and an analysis of the surface of the steel plates with ESCA (Electron Spectroscopy for Chemical Analysis) showed that the frictional properties are significantly affected by the additives adsorbed on the clutch plate sliding surface.

In the field of automobile disk wheels, demands for aluminum wheels have been increasing for the reason of ride comfort and better appearance. And over 90 percent of luxurious passenger cars are equipped with aluminum wheels. This trend is spurred also by the demand for higher fuel efficiency for the cause of environmental protection, which calls for weight reduction of automobiles. This paper reports our research on manufacturing light-weight, high-quality aluminum cast wheels; covering the entire process from basic design to casting, and placing emphasis on the following three points. 1) Determination of optimum wheel configuration through computer simulation 2) Selection of optimum material composition 3) Optimization of the thin plate casting conditions Combination of the above technologies developed for the purpose of weight reduction resulted in the weight reduction of approximately 20% over the conventional aluminum wheels.

Various dies have been used for producing many internal and external parts of an automobile. This paper describes the method of ‘High Speed Die-sinking’ that is one of the key technologies for die-making. We analyzed the milling mechanism of a typical Ball End-Mill used for die-sinking and performed cutting tests. As a result, we have achieved high speed and fine quality die-sinking technology. Its feed speed is about four or five times as fast as before, and the irregularity of the milled surface is under one-fifth as compared with previous level. In addition, we will propose the new method for estimating finishing performance by ball end-mill.

Sintered silicon nitride, particularly in structural ceramics, has superior properties such as low weight, heat resistance, wear resistance, etc. It is already being applied to automobile engine parts such as the swirl chamber and the turbine rotor. In recent years, the strength of silicon nitride has shown to be above 1000MPa. This has been achieved through advances in manufacturing technology such as materials powder, forming, sintering and so on. But the silicon nitride is easily damaged during grinding because it has less fracture toughness than metal. Consequently, the inherent strength of the material is not demonstrated in the actual products presently produced. It is assumed that the main cause of strength reduction is microcrack. In ordinary grinding methods, the length of microcrack has been estimated at approximately twenty micrometers by fracture mechanics analysis.

So far in conventional automotive meter, reflection of the incident light on a cover glass is prevented by a hood and a curved cover glass. Anti-reflection coating (hereafter abbreviated as AR coating) on the surface of cover glass can offer a meter without the hood. Thin films of AR coating are uniformly deposited on a large polymethylmethacrylate substrate in an ambient atmosphere by sol-gel dip coating and cured at low temperature. The AR coated panel shows a very low reflectance. In addition, the AR coating has a high reliability for the instrument panels of automobiles. The AR coating meter offers new instrument panel design for Toyota Prius.

Recently, single action draw with cushion replaces draw with double action presses. In the single action draw, binding fluctuation problem occurs by its structure. We applied an NC cushion to prevent the problem. We compared the cushion force wave with and without an NC cushion. The NC cushion showed effective damping. We studied the binding force control of a side member outer panel. The panel didn't have the formable range of binding. This means the lowest binding force to avoid wrinkling, still had crack problems. We introduce four patterns of binding force control with the NC cushion. As a result, we found the suitable pattern to suppress the surface distortion. Controlling the binding force shows effectiveness as a means of suppressing surface distortions.

The fluorescent magnetic particle inspection is widely used as a visual inspection method for checking cracks generated in hardening and grinding of induction-hardened parts. However, automation of this inspection process has strongly been demanded, due to poor environmental conditions and production line speed. To satisfy such a demand, we have developed a method for picking up images of automotive parts with higher S/N ratio and an original algorithm for image processing which helps measure cracks accurately without being affected by the illuminance and magnetic particle solution concentration. Then we selected the front axle shaft as the object to study practical use and have solved various technical problems in actual use, thereby succeeding in actual application to our production lines.

To more effectively improve the work on a vehicle assembly line, it is desirable to have a method by which the degree of work load on each person can be evaluated quantitatively; enables us to decide the priority order of improvement; and calculates the improvement effect. We developed a quantitative evaluation method of work load by introducing a concept of physiological stress generated regardless of the type of muscles involved. Applying the burden borne by the body to the load evaluation of various assembly operations involved the problem of complex load measuring methods. We solved this problem by categorizing the load conditions for various assembly operations and converting each to a standard state of loads evaluated by experiments.

New ductile cast iron flywheel integrated with gear and its manufacturing process were developed to reduce the manufacturing steps and cost compared with conventional flywheel around which a steel ring gear is fit. In this process, the ring gear teeth around a cast iron flywheel are formed directly in net shape and free from any defect by the hot form-rolling method, followed by the thermomechanical treatment in a short time. The gear is superior to that made by the conventional hobbing and heat treatment in accuracy, strength and anti-wear property.

A new technologies for manufacturing of engine valve seats have been developed. This process, different from the conventional method that valve seats made of sintered alloy were press-fit into the cylinder head, is directly formed valve seats onto cylinder head by using the laser cladding technique. In order to develope the cylinder head with laser cladding valve seats, the laser cladding technology by which copper based alloy is deposited onto aluminum alloy with little dilution and stable bead has been established. And the unique cladding alloy, which is two phases in the liquid stage and in which iron or molybdenum rich hard particles are dispersed in the solid state, has been developed. Based on this technique, the practical process has been successfully completed.

This paper presents an improvement in the accuracy of NOx sensors at high NOx concentration regions by optimizing the manufacturing process, sensor electrode materials and structure, in order to suppress the deterioration mechanism of sensor electrodes. Though NOx sensors generally consist of Pt/Au alloy based oxygen pump electrodes and Pt/Rh alloy based sensor electrodes, detailed experimental analysis of aged NOx sensors showed changes in the surface composition and morphology of the sensor electrode. The surface of the sensor electrode was covered with Au, which is not originally contained in the electrode, resulting in a diminished active site for NOx detection on the sensor electrode and a decrease in sensor output. Theoretical analysis using CAE with molecular dynamics supported that Au tends to be concentrated on the surface of the sensor electrode.

We have developed a new torsional damper spring which lowers the torsional rigidity of the clutch disc while retaining its conventional size. The following two items have been adopted in the newly developed spring: 1) A new steel wire which suppresses any core-softening of the element wire through nitriding. 2) A dual-stage shot peening method which uses harder steel shots (rather than conventional shots) in order to obtain an optimal residual stress profile. As a result of evaluating the fatigue characteristics of this spring, it was discovered that its fatigue strength is approximately 35% higher than that of the conventional spring. A clutch disc using this spring was able to absorb rattling noises which conventional clutch discs could not.

A high strength and high toughness new bainitic steel has been developed which shows comparable mechanical properties, fatigue property, and machinability to those of quenched and tempered SAE 5140. The heat treatment of the bainitic steel is aging after hot forging in order to improve ratio of 0.2% proof stress and tensile strength (i.e. yield ratio) and to avoid warpage associated with quenching. The new bainitic steel has been applied to the slender and lightweight lower arms for automotive suspension. As a result, the total production costs in the lower arms have been reduced by nearly 15 percent.

Mass reduction of parts is growing in importance as a means for reducing CO2 emissions from vehicles.The aim of the present research was to contribute to further mass reduction of pistons by developing a new aluminum casting material with highest level of fatigue strength. This goal was achieved using a development concept of creating a homogeneous structure in which Ti was added to create a fine structure and appropriate quantities of Fe and Mn were added to form a compound that is stable at high temperatures. Stand-alone tests of prototype pistons fabricated using the developed material show that the material is 14% stronger than the conventional material, thereby enabling increases in power and mass reduction.

Instrument clusters used in automobiles play an important role as man-machine interface. A variety of information about the current driving situation is conveyed to the driver quickly and accurately. A great interest has been taken in the high visibility and legibility of the head-up display (subsequently abbreviated as HUD). Originally developed as display used in aeronautical applications, we have tried to exploit ways to adapt this device for automotive use. We have succeeded to produce a new HUD system, which has the following design features; (1) High brightness and high contrast display device using a liquid crystal display (subsequently abbreviated as LCD) and a halogen lamp illumination. (2) Long focus display in two colors using holographic lens. (3) Automatic dimming control system using an illuminance sensor. (see Fig. 1)

This paper describes the development of one-piece die cast magnesium steering wheel frame for a steering wheel incorporating an air bag system. The light weight magnesium frame was designed to have proper stiffness, strength and characteristics of energy absorption. Magnesium alloys with various aluminum contents were tested, and AM60B alloy was selected because of its favorable properties of strength and elongation. New manufacturing techniques, for example, a vacuum hot chamber die casting system and a surface defect inspection system were developed in order to produce high quality castings. The characteristics of energy absorption were evaluated in the laboratory and on actual vehicle crash test, and the results were satisfactory. The magnesium steering wheel frame is about 45% (550g) lighter than the steel one. It has been in production in Toyota passenger cars with driver side air bags.

Toyota Motor Corporation has mass-produced turbochager with sillicon nitride ceramic rotors. A moment of inertia was reduced by 60% using ceramic rotor which improved turbochager response. The ceramic rotor was joined to metal shaft by new method which compensated problems in both shrink fitting and active brazing methods. They are generals for mechanical and chemical techniques, respectively. There still exist the following disadvantages. It is quite severe to controll the clearance of shrink fitting to obtain the reliability of the joint. The shaft may be loosened at high temperature with a small shrink-fit interference. The large shrink-fit interference could result in a failure of ceramic shaft due to large stress. Those may require a machinig accuracy with micron meter order of surface roughness which, leads to high cost.

A new, free-cutting steel, hereafter referred to as “non-lead-added free-cutting steel”, has been developed with the intention of replacing currently applied lead containing free cutting steel. The ultimate goal of this project is to provide a new lead-free steel grade that will contribute to the removal of environmentally harmful substances from automobile parts. In this project, we have targeted the development of a material that would demonstrate levels of machinability and other mechanical properties equivalent to those of the conventional free-cutting steel to which sulfur (S), lead (Pb) and calcium (Ca) or combinations, thereof have been added. The fine dispersion of sulfide, modified by adding Mg and Ca, is most effective in enhancing the chip breakability that would otherwise deteriorate due to the absence of lead. The practical application of the non-lead-added free-cutting steel has rendered the goal of total removal of lead from special steel products highly obtainable.