Effect of oil film behavior on roller surface on cooling in traction drives

This paper describes the relationship between the oil film behavior and cooling effect of traction drive roller experimentally. Traction drives are transmission systems where the power is transmitted by shear stress of lubrication oil on the contact point between the rollers. They have advantages regarding noise, vibration, and high-speed operation compared with gears. On the other hand, when the power is transmitted, the heat generation occurs caused by the creep and spin at contact points. This leads to decrease of traction force and then leads to reduction of mechanical efficiency of power transmission. Thus, traction drives need the additional cooling device or the supplying of a large amount of cooling oil. However, these cooling method causes an increase of device weight, device cost, and energy consumption. From this background, the authors focused on the cooling effect of oil film behavior on traction roller. In this study, the oil film behavior was observed, and oil film temperatures were measured. As a result, it is found that oil film temperatures are affected by the oil splashing from the roller surface and the oil film distribution. Further, the authors proposed a new geometry of the roller surface which can expect to increase the cooling effect by the oil film.