Patent ID: 8578710

Claim:
A cup seal comprising: a circular base portion housed in a depressed portion and extending in a radial direction, a circular inner lip portion disposed in the base portion and extending in an axial direction from the inner peripheral side end portion thereof, a circular outer lip portion disposed in the base portion and extending in the axial direction from the outer peripheral side end portion thereof, and separably making contact with a bottom wall of the depressed portion, and an intermediate lip portion disposed in the base portion, positioned between the inner lip portion and outer lip portion, and extending in the axial direction, wherein the base portion includes an easy elastic deformation portion, which elastically deforms in the axial direction comparatively easily, and a difficult elastic deformation portion, which does not elastically deform in the axial direction as easily as the easy elastic deformation portion, wherein in the intermediate lip portion, a plurality of first and second intermediate lip portions are disposed in a circular form, and intermittently, either side of intervals with no lip portion extending from the base portion, the first intermediate lip portions being disposed in the difficult elastic deformation portion of the base portion and the second intermediate lip portions being disposed in the easy elastic deformation portion of the base portion, at least one of an axial direction length and a thickness of the second intermediate lip portions being less than that of the first intermediate lip portions.