A Study on the Friction Reduction of Seal Rings for Automatic Transmission

In this study, we have developed two type of low friction seal rings (S/R). The first of developed product is textured seal ring. The surface textures with the side of seal ring are designed by using numerical analysis of hydrodynamic, and attempt to reduce the friction coefficient by lubrication improvement of sliding surface. Low friction effect is confirmed by friction torque and oil film thickness measurement, and it was discussed from analysis and experiments. The second is outer sliding type seal ring. This seal ring is unaffected by the environmental factors, it is possible to a pressure-receiving area reduction by changing the sliding surface from the side to the outer. Friction characteristics and sealing performance have been evaluated by the sliding test. Also both developed seal rings were confirmed that the low-torque effect compared to conventional one (T-shaped cross section seal ring) is obtained.