2018 Volume 4 Pages 17-00654
Power devices used for power control in electric vehicles have the drawback of high heat-generation, which can be effectively addressed by water-cooling. Their durability is affected by the performance of the seal lip in the coolant pump. The seal lip, in which a rotating shaft passes between liquid and gas phases, plays an important role in the separation of the two phases. To cool power devices, a specifically designed seal lip is required, as the seal lip is subjected to high pressure and temperatures of the water-based coolant and high-speed shaft rotation. A new type of seal lip has been developed by employing a biomimetic mechanism in which the hydrated lubrication mechanism found in natural articular cartilage is adopted. A fiber-reinforced PVF (polyvinyl formal) was employed as the hydrated and biomimetic seal lip material. The bio-inspired seal lip was attached to the shaft. Shaft rotation was controlled by a servomotor, which generated a speed of 5,000 rpm (revolutions per minute). An LLC (long-life coolant) was used as the coolant, which was diluted with distilled water at a concentration of 50%, heated to 75 °C, and pressurized to 0.3 MPa. Although the continuous leakage of LLC was observed, it was estimated that the bio-inspired seal lip might prevent the abrupt function failure in air-LLC separation. The frictional torque of the bio-inspired seal lip was lower than that of the conventional oil seal. These results suggest that the bio-inspired seal lip is a useful component in the water-cooling systems of high-power devices.
