Patent ID: 6860486

Claim:
A shaft sealing ring comprising the following features: (a) the shaft sealing ring includes a sealing lip which is made of an elastomer; (b) the sealing lip is flaccidly bendable or flexible, its flexural elasticity being chosen sufficiently great to press a sealing portion of the sealing lip into sealing engagement with the periphery of the shaft, without any additional contact pressure means; (c) at the side of the shaft, the sealing lip is provided with at least one undulating, closed, continuous return channel around the circumference of the sealing lip, which channel acts to return exiting medium during rotation of the shaft to the space to be sealed and is blocked towards the surroundings; (d) the sealing portion of the sealing lip engages the periphery of the shaft for a predetermined axial length which is dimensioned at least so that the sealing lip will fully contact the periphery of the shaft both at the front edge of the at least one or each return channel at the side facing the medium and at the rear edge of the at least one or each return channel facing the surroundings; (e) the rear edge of the first return channel facing the surroundings is pressed into contact with the periphery of the shaft by at least the same amount of pressure as the front edge of the first return channel facing the medium; (f) the tangent to the front edge facing the medium and to the rear edge of the first or last return channel facing the surroundings is inclined with respect to the axial direction of the shaft of an angle of inclination in the range between 1° and 5°.