Sealing ring

A sealing ring which is mounted to an annular groove provided on an outer circumference of a shaft and seals an annular gap between the shaft and a housing that rotate relative to each other to maintain fluid pressure of a region to be sealed that is configured such that the fluid pressure thereof changes,

• wherein the sealing ring includes an inner circumferential surface, an outer circumferential surface and a pair of side surfaces, one of the pair of side surfaces slides against a side wall surface on a low pressure side of the annular groove,
• a dynamic pressure generating groove disposed in the one of the pair of side surfaces of the sealing ring, the dynamic pressure generating groove includes
• a first groove radially spaced from the inner circumferential surface of the sealing ring and having a constant width in a radial direction along the entire length of the first groove in a circumferential direction and extending in the circumferential direction and
• a second groove that is recessed directly from the one of the pair of side surfaces which slides against the groove side wall surface and is narrower than the first groove in a circumferential direction and extending from a center position of the first groove in the circumferential direction to the inner circumferential surface of the sealing ring and guiding a fluid to be sealed into the first groove,
• the first groove is provided at a position within a sliding region which slides against the side wall surface, wherein end portions of the first groove are separated from the inner circumferential surface of the seal ring by inner walls which are coplanar with the one of the pair of side surfaces of the sealing ring, wherein the inner walls have a constant width in a radial direction,
• the sealing rind has a constant width in the axial direction at regions where the inner walls are provided and the constant width is equal to a width at a region where the inner walls are not provided,
• a portion of the first groove that connects to the second groove has the same depth as the second groove and is deeper than the other portions of the first groove, and
• a step, defining an abrupt deeper transitional region, is formed between the portion of the first groove that connects to the second groove and the other portions of the first groove, wherein a depth of the first groove on opposite sides of the step changes in the circumferential direction.