Patent ID: 7722051

Claim:
A seal assembly comprising: a seal ring; two members assembled concentrically and rotatable with respect to each other; a first sealing face of the seal ring sealing a surface of one of the two members; a second sealing face of the seal ring, said second sealing face sealing a side wall face of an annular groove formed in the other of said two members and being located on a side of an unsealing fluid so that an annular clearance between said two members is sealed by the first and the second sealing faces; and a separation of said seal ring being located at one circumferential portion of said seal ring, a relief of said seal ring keeping a part of the second sealing surface out of abutment with the side wall face of said annular groove on the side of said unsealing fluid, said relief being formed throughout a circumference of said second sealing face; said relief having a first portion located in a vicinity of said separation, a second portion spaced away from said separation, and a third portion located between said first portion and said second portion; said first portion of the relief having a first outer radius that is shorter than a second outer radius of the second portion of the relief, and the second sealing face having an outer radius longer than said second outer radius; and said third portion of the relief having a gradually changing third radius, said gradually changing third radius extending in a circumferential direction of the seal ring and the gradually changing third radius being located between the first outer radius and the second outer radius.