Patent ID: 7722052

Claim:
A rotation shaft seal provided with a rubber portion having a lip portion to contact a surface of a rotation shaft and an outer case of metal to which the rubber portion is unitedly fixed, comprising a construction in which the outer case has a cylindrical wall portion corresponding to an inner peripheral face of a housing, a staged portion is formed on a middle position in an axis direction of the outer case and on the cylindrical wall portion to divide a small cylinder portion on a high-pressure side and a large cylinder portion on a low-pressure side, an end face on an inner side of the staged portion is unitedly covered by a part of the rubber portion to dispose a rubber end face in an axis-orthogonal direction as to be directed to the low-pressure side, and a face of a peripheral edge of a seal element facing the high-pressure side is press-fit to the rubber end face; wherein a small ridge and a small concave groove are concentrically formed on the rubber end face in unpress-fit state of the seal element, and rubber material of the small ridge is elastically deformed as to flow into the small concave groove by press-fitting of the face of the peripheral edge of the seal element as to keep sealing in press-fit assembly state of the seal element; an end face-covering ring rubber portion, composed of the part of the rubber portion and covering the end face on the inner side of the staged portion is provided, and an inner member of metal, receiving a high-pressure side of the seal element and an inner peripheral face of the end face-covering ring rubber portion, is attached; the small ridge is disposed on an inner-peripheral corner portion on the low-pressure side of the end face-covering ring rubber portion, the small concave groove, having a radius dimension larger than that of the small ridge, is disposed near the small ridge, and a peripheral face of the inner member stops inward flowing of the rubber material of the small ridge in a radius direction in the press-fit assembly state of the seal element; and wherein a supporting metal is provided, a peripheral face of the supporting metal is elastically pressed to an inner peripheral face of a thin inner face covering portion of the rubber portion, and an end face of the supporting metal contacts the inner member.