US Patent 11060615 Labyrinth seal

A labyrinth seal includes a step portion formed on an outer circumferential portion of a rotary body, a fin extending radially inward from an inner circumferential portion of a stationary body, and an annular groove formed in the outer circumferential portion of the rotary body. The step portion includes a diameter-increasing step portion and a diameter-decreasing step portion. The fin includes a first fin, a second fin, and a third fin. The annular groove is disposed in at least a part of a region that is located close to the low-pressure side compared to the high-pressure-side step portion and close to the high-pressure side compared to the third fin.