Strategy of directional oil transport for splash lubrication systems

Abstract

Supplying oil to bearings rapidly over long distances presents a challenge for splash lubrication systems in drive axle main reducers (DAMRs), mainly because of inadequate driving forces. To mitigate this issue, a novel strategy was introduced to control the splash oil flow via a shroud, which enabled directional oil transport. We developed a transient modeling framework to comprehensively investigate the temporal and spatial evolution mechanisms of splash oil. This framework, validated through empirical studies, navigates the uncertainties and multiscale properties of the multifaceted physics induced by the dynamic boundaries of a shrouded gear. Several operating scenarios were simulated to investigate the driving mechanism of directional oil transport within the shroud, as well as the effect of shroud design and rotational speed on splash lubrication performance. Results demonstrate that the pressure gradients inside and outside the shroud govern the directional transport of the splash oil flow. The bearings located distally on the sump receive a considerable volume of oil (maximum flow rate exceeding 11 L/min) from the upper passage. Concurrently, the churning losses in the DAMR are reduced by >30 % when the wheel is shrouded in comparison to an unshrouded scenario. Moreover, interactions involving friction and collision between the gear and fluid particles intensify with increasing speed and enhance shroud sealing. This study provides a valuable mechanism for investigating oil transport in splash-lubricated DAMRs.