Study Of Pumping Effect Of Rotary Lip Seal

Pumping effect means that the oil leakage can be draw back from the air side into the oil side by the seal. Pumping effect takes effect only when the leakage occurs, no leakage is no pumping effect. Pumping effect plays a crucial role in dynamic sealing of rotary lip seal, and study of pumping effect and its influence factors is helpful for seal designing.An equation of pumping rate is formulated from macro-theoretical-model. The influences of film thickness, contact pressure, contact width, lip angles, rotating speed and spring offset on pumping effect are analyzed. The results show that the seal can generate pumping effect only when the oil-side-angle larger than the air-side-angle. The pumping rate increases with the increase of the oil-side-angle, while decreases with the increase of the air-side-angle. The increase of contact pressure would enhance pumping effect. The pumping rate will quickly increase with the increase of film thickness while the contact width increase will lead to a decrease of pumping rate. The pumping rate will increase with rotating speed which increase will cause an increase of film thickness.A CFD model was build up from the Taylor-vortex theory to study the pumping effect. The influences of film thickness, contact width, lip angles, rotating speed on pumping effect caused by Taylor-vortex are analyzed. The results show that Taylor-vortex exists only in wedge areas on both sides of the sealing area. Taylor-vortex in wedge area will generate pumping effect when the shaft rotates. But this pumping effect is much smaller than the experimental value, so it can be neglected.