Patent ID: 8413995

Claim:
An oil seal comprising: a seal lip in slidably close contact with a circumferential surface of a mating member; a first slope at the side of sealed fluid and a second slope at the side opposite to the sealed fluid, both of which are provided on the seal lip; and a first screw section provided on the second slope at the side opposite to the sealed fluid to perform a function of pushing back sealed fluid by a pumping effect induced at a time of rotation, the first screw section being threaded in a first direction, wherein an intermediate surface is provided between the first slope and the second slope, and a second screw section for performing a function of sucking the sealed fluid by a pumping effect induced at a time of rotation is provided on the intermediate surface, the second screw section being threaded in a second direction which is opposite to the first direction, and the second screw section provided on the intermediate surface is provided so that the second screw section does not reach a boundary between the intermediate surface and the second slope at the side opposite to the sealed fluid, so that a threadless region is provided on the intermediate surface, the threadless region lying in the entire circumference between the second screw section and the boundary and being in close contact with the circumferential surface of the mating member, wherein the intermediate surface has an inner diameter size expanding from the side opposite to the sealed fluid to the side of the sealed fluid so that an entirety of the intermediate surface has an angle θ at the side of the sealed fluid in a mounted state, and wherein the intermediate surface angles differently than the first slope and the second slope.