Experimental analysis of the power losses induced by a high-speed lip seal under oil bath lubrication

The electrification of automotive powertrains raises major challenges in efficiency and thermal management. Among the contributors to load‑independent power losses, lip seals remain insufficiently characterized at high rotational speeds and under oil‑bath lubrication. In this work, the behaviour of an industrial Viton (FKM) lip seal was experimentally investigated over a wide speed range (0-12 100 rpm, 25 m.s -1 ) and under various lubrication conditions, from fully immersed oil baths to unlubricated operation. A dedicated high‑speed test rig enabled direct measurement of friction torque, lip temperature, and leakage. shows that the oil level is a dominant parameter governing the seal behaviour. Increasing the oil bath level led to a non-negligeable increase of the seal friction torque. However, higher immersion ensures uniform cooling, while tangent configurations lead to non‑uniform circumferential temperatures due to oil film break‑up by centrifugation. A factor is proposed to consider the increase of the friction torque generated by the oil bath level. After correcting the cylindrical churning contribution of the shaft, the seal torque remains nearly constant with speed for immersed configurations, while a slight decrease is observed for tangent lubrication, indicating mixed lubrication behaviour for the latter. Under unlubricated conditions, friction torque remains comparable to lubricated operation, but wear rate increases by an order of magnitude, highlighting the essential lubricating and cooling role of the oil bath. Comparison with ISO/TR 14179 standards confirms that ISO/TR 14179‑2 and ISO/TR 14179‑1 requires calibration of the linear coefficient. • An experimental methodology to correct the shaft churning torque is provided, • The friction torque is function of the oil level and the rotating speed, • The heat generated by seal’s friction is dissipated through the oil bath, • A tangent oil bath with a non-immersed rotor ensures sufficient seal lubrication, • Existing global and standards models may overestimate seal losses.