We aim to reduce the number of prototypes and evaluations as part of efforts to achieve carbon neutrality in head gasket development. For that purpose, it is important to improve the accuracy of performance prediction by CAE performed at the design stage. This time, we will introduce our newly developed gas sealability prediction technology. By incorporating the deterioration of rubber that occurs during engine evaluation into the analysis conditions, the product life can be predicted with higher accuracy. Rubber degradation, which is difficult to quantify, is predicted using a newly developed unit evaluation method. A prediction technique that combines evaluation results and analysis results enabled us to estimate a valid product life. In the future, we would like to proceed with further studies in order to make the technology versatile.

Recent progress in the enhanced ignition system, including the conventional spark ignition system, was introduced in this report. At first, the spark discharge channel behavior and its effect on the ignition of lean or diluted mixture was discussed. Next, as novel ignition technologies, the low-temperature plasma ignition system and the pre-chamber ignition system were introduced, and the performance of those systems were discussed.

This paper presents the experimental method and several results obtained in the author's laboratory. In current internal combustion engine technology, pattern-coating pistons are often used to reduce friction losses. To know the engine oil distribution pattern with pattern-coating pistons is one of the fundamental and important topics for obtaining better engine efficiency. The author's group has been trying the visualization of engine oil behavior on piston skirt. Experiments have been conducted on a two-cylinder boxer type test engine. One cylinder of the engine was made of transparent sapphire for visualization. The coating patterns for the test were stripes and polka dots. LIF (Laser Induced Fluorescence) is applied to measure the oil film thickness distribution. The results show the effect of the coating-pattern on the oil film thickness. The boundary lubrication area is also shown from the experimental result. These results can be used for optimization for coating-pattern on the piston skirt.

A cylinder block involves bore deformation due to assembling stress of cylinder head and thermal stress. Friction analysis method of a piston skirt was established and the bore deformation effect on engine performance was clarified. Bore distortion analysis revealed the bore profile of constriction at bottom side and expansion toward upper side in the case of normal bore. This distortion is found to be the cause of exacerbation of the trade-off between skirt friction and piston slap. As a result of CAE prediction, ideal cylindrical bore under the highest thermal load condition significantly improved skirt friction, blow-by gas flow and LOC. Simulation results indicated that the change of design parameters for piston and rings lead to additional improvement of engine performance.

To achieve the carbon neutrality, initiatives have been working to reduce carbon dioxide emissions around the world. In the automotive industry, downsized engines combined with turbocharger have been one of effective solutions to improve fuel efficiency, this technique has been widely used to reduce carbon dioxide emissions. In particular, turbine wheels in the turbocharger, which are exposed to high temperature exhaust gas and rotate at high speed, required the highest heat resistance, thus the materials such as Ni-based alloys and TiAl-based alloys have been used. In the future, the material properties required for turbine wheels will change with the spread of hybrid automobile and engines using hydrogen gas and synthetic fuels become more widely used.

The multi-link piston-crank mechanism which implements variable compression ratio consists of multiple links and bearings which connecting links. Therefore, it was very important how to design the journal bearings and bushes which is added as important elements to constitute the multi-link mechanism. In this paper, it is explained that how to design the journal bearings and bushes for multi-link piston-crank mechanism based on each peculiar load characteristic and sliding characteristic. At that time,each dynamic characteristic and cooling effect by the engine oil by the added oil feeding path was considered.

To reduce maintenance costs of current collecting materials such as contact wires and contact strips, measures to reduce their wear based on wear mechanisms are needed in electric railways. The authors have clarified that there are four mechanical wear modes of current collecting materials. However, the transition to seizure has not been explained. The transition to seizure is considered to occur as the number of contact points decreases, however any decreases in the number of contact points have not been verified in our previous report. In this paper, a model for analyzing contact temperatures considering the number of contact points was constructed, and the number of contact points was estimated by compering analytical and experimental results. The results of the analysis showed that when the thermal conversion ratio from friction work to friction heat was set to 60%, the error of the contact temperature estimation was about 15%. It was found that the number of contact points of seizure was less than that of adhesive wear. The surface pressure was calculated from the estimated number of contact points, and it became clear that the transition to seizure occurs when the surface pressure exceeds the hardness of the material.

The effect of crystallographic orientation on the friction force and the adhesion force in pure iron with three different surface orientations are investigated by electron backscatter diffraction pattern (EBSD) and atomic force microscopy (AFM) within lateral mode and fast force map mode under Ar gas. Both the friction force is found to increase in the sequence (100) < (111) < (110) and it increases in the same order with the adhesion force. The adhesion force might be controlled by the surface energy and the contact area. However, the orientation dependence of adhesion force cannot account for the order of the surface energy and the contact area calculated with Herz contact theory. Instead, this study focuses on the effect of the work function which is the energy to need to remove an electron from a solid surface to ideal point. The work function obtained by the AFM analysis demonstrates a good correlation with adhesion force. It is concluded that, therefore, the adhesion phenomenon on the between solids is controlled by the electrical interacting force.