Patent ID: 7338255
Filing Date: 2008-03-04
Classification: F04D

Abstract:
1. A turbo-type fluid machine comprising a rotating shaft arranged in a pump casing, an impeller mounted on the rotating shaft, and a mouth ring part provided between a shroud of the impeller and the pump casing and having a seal function, and wherein the mouth ring part comprises an impeller ring on a side of the shroud of the impeller and a casing ring provided on a side of a non-rotating body wall surface of the casing, the impeller ring is structured to have a stepped portion that is in the form of a staircase with at least two steps to be small in diameter toward a suction side of the impeller and large in diameter toward an outlet of the impeller, and the casing ring is labyrinth-shaped to have a projection and a recess, a narrow clearance part having a narrow radial clearance is formed between the projection and the impeller ring, and a flow passage spatial portion defining an enlarged portion of the narrow radial clearance is formed by the recess and the stepped portion of the impeller ring.