Influence of an applied electric field on the torque of rotary lip seals on metal shafts. Part I: Effects of lip seal type

The paper presents some results of experiments on the tribocharging of selected engine oil and on the effect of an auxiliary external DC electric field on the work of machines which contain rotating parts such as shafts, crankshafts, etc. The research was especially aimed at the braking torque of a rotating metal shaft sealed with a lip seal and a possibility of reduction in the torque under external DC electric fields. DC voltage was applied between the stiffening ring of four different lip seals under test and a rotating, earthed shaft in a metal shaft-oil film-lip seal system. The relationships of the torque to the voltage of positive and negative polarities were established on the basis of measurements of the torque under steady-state conditions for a constant oil temperature and given different angular shaft velocities. In general, it was found that positive and negative DC electric fields produce adverse effects on the torque depending on the type of oils and on the material of which the lip seals were made. In only one case, the torque decreased with the increasing absolute value of the negative voltage applied.