Effect of Micro Bubble on Stirring Resistance of Traction Roller

Abstract

Motors for electric vehicles are expected to be equipped with reduction gears for traction drives suitable for high-speed rotation to make them smaller and more efficient. However, if a large amount of lubricating oil is supplied, large agitation resistance due to lubricating oil is generated around the roller, which is thought to cause energy loss. Therefore, we focused on the friction reduction effect by microbubbles in this study. If the microbubbles enter the contact point, there is a risk of breaking the oil film and making direct contact. As a result of visualizing the flow around the contact point, the risk of direct contact was judged low. Therefore, the roller was immersed in lubricating oil mixed with microbubbles to visualize the wall flow of the rotating roller. The visualized results were analyzed using the PIV analysis, and the effect of the microbubbles on the stirring resistance was evaluated from the difference in flow velocity between the roller with and without micro bubbles. The results of the PIV analysis showed that the speed was reduced in the case of lubricating oil mixed with microbubbles.