Host: The Japan Society of Mechanical Engineers
Name : [in Japanese]
Date : September 03, 2023 - September 06, 2023
To extend the cruising range of electric vehicles (EVs), it is necessary to improve the efficiency of EVs. As one method to improve the power consumption of EVs, the increase of motor speed is expected. The increase of motor speed makes it possible to reduce the size and weight, which leads to increase power output of EVs. However, the fatigue life of the bearings and gears will decrease; therefore, micropitting will increase. Diamond-like carbon (DLC) film is expected as one way to prevent the micropitting of bearings and gears. DLC has various excellent tribological properties such as low friction and high wear resistance. However, evaluation method for micropitting in DLC has not yet been established. In addition, in the contact surface of gears, sliding and rolling contact occur at the same time. In previous studies, it has been reported that fatigue surfaces are eliminated by wear due to sliding. Therefore, to clarify the effect of rolling contact on the occurrence of micropitting, it is necessary to conduct tests under pure rolling contacts, where the effect of sliding is minimal. In this study, we applied two types of DLC film (a-C:H, ta-C) to the surface of balls. Ball-on-disk tests were conducted under the conditions of lubrication of base oil and pure rolling contact to investigate the effect of these types of DLC film on micropitting resistance. We confirmed that the ta-C type DLC film suppresses micropitting.
