弾性流体潤滑下の絶縁破壊に及ぼす潤滑油の粘度圧力係数の影響

摘要

モータの故障原因の一つに軸受の電食がある．軸受が電食するとモータは騒音を発するようになる．この軸受の電食がインバータ駆動するモータの一部で起こっている．環境に優しい電気自動車や風力発電などインバータを使う場面は今後さらに増えると考えられ，軸受電食の原因究明および防止対策が求められている．%Electrical pitting resistance of lubricants is evaluated with a modified optical interferometry device. The device can observe the electric discharge phenomenon as a flash signal so that it is possible to detect directly the flash position in point elastohydrodynamic lubrication (EHL) contacts, while observing the shape and thickness of EHL films. Five kinds of base oils, two kinds of gel-lubricants and four kinds of ionic liquids are investigated. The base oils are chosen to examine the influence of the pressure-viscosity coefficient. Since the gel-lubricant has a polar group and the ionic liquid has a low volume resistivity, they may bring about higher pitting resistance, because of their high electric conductivity. It has been however found that the higher electric conductivity does not necessarily bring higher pitting resistance. It has also found that the pitting resistance is expressed as a function of the pressure-viscosity coefficient. The larger pressure-viscosity coefficient brings about the higher electrical pitting resistance.