Analysis of Piston Friction in Internal Combustion Engine

Hybrid vehicles (HVs) are becoming more widely used. Since HVs supplement engines drive with motor power, the lubricant oil temperature remains at a lower level than in a conventional gasoline vehicle. This study analyzed the effect of cylinder liner temperature and lubricant oil temperature on engine friction. The results showed that, although the lubricant oil temperature was hardly significant, the liner temperature had an effect on piston friction. It was found that raising the temperature of the middle section of the cylinder liner was the most effective way of reducing piston friction.HV車など低燃費車両の普及でエンジンの低温領域が拡大し、燃費向上のためにその領域の摩擦低減のニーズが高まっている。本研究では、エンジン中最も割合の大きいピストンの摩擦に着目し、ボア壁温分布と油温の寄与率を調査した。その結果、ピストン速度が最大となる摺動位置のボア壁温を上昇させることが有効とわかった。