Lip seal device having an annular groove

摘要

A lip seal device for sealing the gap between a housing and a rotary shaft comprises a case surrounding the rotary shaft, a lip seal attached inside the case, support means for holding the lip seal on the other circumferential portion thereof and seal means located on the outside circumferential surface of the case. The inner circumferential portion of the lip seal is curved toward the sealed fluid. The lip seal includes a sealing surface provided with an annular groove extending continuously in the circumferential direction of the rotary shaft so that the sealing surface has a first and second sealing portion, the contact pressure of the first sealing portion on the rotary shaft being lower than the contact pressure of the second sealing portion on the rotary shaft.