Investigations on lubrication characteristics of high-speed electric multiple unit gearbox by oil volume adjusting device

In this paper, a numerical simulation model of the flow field in a gearbox with an oil volume adjusting device is established for the first time to study its influence on the lubrication characteristics of a high-speed electric multiple unit (EMU) gearbox. The moving particle semi-implicit (MPS) method is used to numerically simulate the internal flow field of the gearbox of the high-speed EMU under working conditions. The effects of the velocity of the high-speed EMU, the immersion depth, and the oil sump temperature on the power loss of the gears and the lubricant quantity of each bearing are studied and provide an effective tool for the quantitative evaluation of the lubrication characteristics of the gearbox. The lubrication characteristics of the gearbox under different working conditions are studied when the oil volume adjusting device is closed and opened. The results show that the oil volume adjusting device mainly changes the amount of lubricant stirred by the output gear by changing the flow rate of lubricant from the cavity pinion (Cavity P) to the cavity gear (Cavity G), and thus affects the power loss of gears and the lubricant quantity of each bearing.