Study on In-Cylinder Thermal Barrier Coatings and Evaluation/Analysis Techniques for Reducing Cooling Losses
-(Third Report) Evaluation of Thermal Properties of Thermal Barrier Coatings II-

Haruka Abe･Kentaro Shinoda･Koichi Kinoshita･Yomonori Urushibara･Megumi Akoshima･Eishi Kubota･Mitsuharu Oguma (AIST)

This study aims to reduce cooling losses and improve engine thermal efficiency by fabricating a thermal barrier coating applicable to pistons using the hybrid aerosol deposition method developed at the National Institute of Advanced Industrial Science and Technology (AIST). In this report, we describe the development of a new thermal barrier coating with lower thermal conductivity than that presented in the second report, and we present the results of evaluating its thermal conductivity characteristics.

Chemical State and Structural Evolution of Metal-Containing Additives in Engine Oil under Different Operating Conditions

Masahiro Kunisu･Xi Li･Daisuke Murata･Sachi Nakashima･Tatsuya Tominaga (Toray Research Center)

X-ray absorption fine structure (XAFS) analysis was applied to metal-containing additives in engine oil for fresh oil, oil after normal operation, and samples subjected to different conditions. Differences in chemical states and local structures depending on usage conditions were identified for the target elements. Under specific conditions, an increase in components exhibiting ionic-like behavior, possibly associated with coordination by water molecules, was observed. These results indicate that the local chemical environment of metal-containing additives can vary significantly with operating conditions.

Friction Reduction Technology for Engine Journal Bearings Based on Oil Film Shear Stress

Motohiko Koushima･Mari Naga･Hiroshi Itoigawa･Tadamichi Tamura･Erina Yasuda (Daido Metal)

Friction loss reduction in engine bearings was investigated by focusing on oil film shear stress. Experiments were conducted using a newly designed test rig. The results indicate that optimization of bearing surface properties is effective in reducing friction loss under hydrodynamic lubrication conditions.

Development of a Friction Evaluation Method under Actual Operating Conditions and Friction Reduction in the Crankshaft System

Kazunori Toida･Takashi Koyama･Makoto Okawa･Teru Ogawa (Toyota Motor)

In automotive internal combustion engines, the indicator diagram methodology is widely used to evaluate friction under the working load of in-cylinder pressure; however, its measurement accuracy remains limited. To address this issue, a practical boosted-motored friction methodology was developed. Friction reduction approaches for the crankshaft system derived from analysis were validated using the developed methodology.