DLC-Si被覆電磁クラッチの表面粗さ制御と表面油溝付与による混合潤滑特性の向上

摘要

駆動力を摩擦によつて伝達する四輪駆動車用電子制御カップリングは，様々な車両で用いられるようになってきている.この電子制御カップリングは，車両の静粛性向上の要求に対応するため，制振性能を高いレベルで維持することが求められている.そのため，主に摩擦係数（μ）の負のすべり速度(V)依存性（μ-V負勾配）に起因して生じるとされる自励振動（スティックスリップ）を防止することが重要となる.%This study investigated how surface roughness of steel disk coated with a Si-containing diamond-like carbon (DLC-Si) film has an effect on friction characteristics, i.e., sliding velocity dependence of friction coefficient, under oil lubricated condition via friction experiments and numerical analyses using mixed lubrication models. It was clarified to be effective for DLC-Si film to have surface roughness of Rz_(JIS) = 3 to 4 μm in order to suppress frictional vibration caused by stick-slip. In addition to the roughness of surface coated with DLC-Si film as a design guideline of sliding surface of electromagnetic clutch with excellent μ-V characteristics, it was found effective for the mating plate to have micro groove structure with depth of 10 μm and pitch of about 100 μm. It was suggested that the surface roughness and the micro groove maintain solid contact even if oil film formation enhances as sliding velocity increases, which results in boundary lubrication.