Influence of rolling-element bearings on rotary shaft seals

Rotary shaft seals are commonly used to seal rotating machine components and prevent the leakage of fluids into the environment. Failures of elastomeric rotary shaft seals are often the result of overheating in the contact area between the sealing edge and the shaft. High temperatures in this contact area occur due to high frictional power and/or inadequate heat dissipation. The surroundig of the seal has a significant impact on the temperatures occurring in the contact area. Studies by Kunstfeld [1] have already demonstrated that additional elements near the seal influence the temperature. Especially rolling-element bearings near the seal strongly influence the contact temperature. The frictional heat generated in the bearings results in an increase in the temperature of the fluid near the seal, consequently raising the contact temperature. Tapered roller bearings pump oil [2] and, depending on the installation situation, can lead to a higher or lower fluid level next to the seal. Tests are conducted on a High-Speed friction torque test bench [3]. This investigation involves four different bearing arrangements, as well as a reference variant without bearings. In these test runs, both the frictional torque and the temperature near the contact area are examined. In addition to the experiments on the test bench, Conjugate Heat Transfer (CHT) simu-lations are conducted with the same installation conditions. The simulated temperatures are compared with the measured temperatures. In most cases, the correlation is good. However, for one bearing arrangement, the correlation is significantly worse [4]. These differences are investigated further.