Development of self-preload type hybrid speed reducing machine using cylindrical roller bearing (2nd report, study of high efficiency)

Authors proposed new system comprises a combination of a gear and a rolling bearing into a traction drive system because the rolling bearing has a function that reduces rotational speed and supports gear reaction forces. The system requires preload to use a rolling bearing as a traction drive. Adding preload axially requires an extra space for the spring to preload. In this study, preload in radial direction was induced to save space by placing a ring outside the outer ring utilizing shrink fitting. When a rolling bearing used as a traction drive, friction between a rolling element and the retainer becomes important. To improve transmission efficiency of the new system comprises a combination of a gear and a roiling bearing, it is necessary to improve a profile of the retainer. By this study, optimization of the curvature radius of the retainer when it contacts a rolling element was investigated. Optimization of the curvature radius of the retainer showed that the improvement of the oil film thickness and the contact pressure. By using the retainer with improved curvature radius, it was found that the transmission efficiency improves to 93.2%. The result observed on the surface condition of the retainer after examination was also reported. The major improvement could be confirmed more than the original flat surface.