| 摘要 |
PURPOSE:To prevent excessive wear of a fusion spray metallization film in the downstream in a turbo charger in which the film is machined with rotation of an impeller and thereby the gap between it and a compressor housing is adjusted to the minimum by changing the film hardness in the fluid flowing direction. CONSTITUTION:In a turbo charger, a fusion spray metallization film 12 is foamed over the inner wall surface of a compressor housing 7 where the impeller tip of a compressor wheel is confronting and is machined by the impeller so that the gap between the impeller tip and housing 7 lessens as much as practicable. The parent materitnl 12a of this film 12 shall be a metal material softer than the material of the impeller, and the final material is produced by mixing this parent material with a still softer material 12b in the form of fine grains. The mixing ratio of this soft material 12b shall be higher in the upstream in the compressor to reduce gradually toward the downstreana, and thereby the film hardness is made relatively lower in the upstream and higher downstream to prevent excessive wear in the downstream commited by the machining splash produced upstream. |
