Patent ID: 7942423

Claim:
A lip type seal being mounted in an annular space between an operating member and a stationary member, and comprising: a resin-made seal body which is devoid of any exterior metal clamping ring and includes: inner and outer circumferential lips which have an approximately cylindrical recessed portion formed therebetween, the cylindrical recessed portion opening toward a first sealing fluid side, the inner and outer circumferential lips being provided at inner and outer peripheries of the cylindrical recessed portion, the inner and outer circumferential lips being slidably in contact with the operating member and the stationary member respectively, a plate-shaped lip which has an approximately wedge-shaped recessed portion having a triangular cross-section and extending radially and opening toward the operating member side at the second sealing fluid side which is axially opposite to the first sealing fluid side, the plate-shaped lip being provided at the second sealing fluid side, the plate-shaped lip arcuately bending from a closed end of the wedge-shaped recessed portion so as to extend in a curved shape toward the second sealing fluid side while slidably in face-to face contact with the operating member, and a solid body section having a rectangular cross-section disposed between the circumferential lips and the plate-shaped lip, said inner and outer circumferential lips being formed integrally with the plate-shaped lip into a one-piece structure; and a spring having a U-shaped section and being mounted in the cylindrical recessed portion, wherein the plate-shaped lip has indentations formed on at least one of: a first surface of the plate-shaped lip that is slidably in face to face contact with the operating member; and a second surface of the plate-shaped lip that is opposite to the first surface, wherein indentations are also formed on an inclined sliding contact surface of the inner circumferential inner lip, and wherein the indentations have a triangular sectional shape, and a first angle of a first inclined surface at a side of an object to be sealed is larger than a second angle of a second inclined surface at an opposite side of the object to be sealed, wherein the first and second angles are respectively formed between the first and second inclined surfaces of the indentations having a triangular shape and the operating member.