Development of CV Joint Grease with Low Friction Coefficient based on Chemical Consideration

摘要

CV joints are one of the fundamental auto components that transmit rotational motion at constant velocity while varying intersection angles and are generally used with a drive shaft or a propeller shaft. In most drive shafts, the outboard CV joint connecting to a wheel is a fixed joint whereas the inboard CV joint near an engine is a sliding joint as shown in Fig.1. Although sliding-type tripod joints shown in Fig.2 are commonly used as an inboard CV joint, they have a problem with vibration often causing an uncomfortable ride. As shown in Fig.3, the axial vibration is generated by roller movements composed of (A) rolling friction and (B) spinning motion of rollers and (C) sliding friction between rollers and needles. The vibration performance can be improved by reducing the friction coefficient of lubricating greases. In fact, CV joint greases developed through our previous studies successfully suppressed the vibration. This paper will describe the results of the thorough examination of supplemental additives to further improve CV joint’s vibration performance and of the analysis to verify the mechanisms contributing to low friction.