| 摘要 |
PROBLEM TO BE SOLVED: To suppress the intrusion of a foreign substance onto a bearing surface.SOLUTION: A supercharger comprises: a housing; a semi-floating metal 17 which is housed in the housing and has a hollow-shaped body part 17a having a bearing surface 17c formed in the inner periphery; a shaft 8 inserted into the body part and having an opposed surface 8b which is opposed to the bearing surface and is journaled rotatably on the bearing surface; a turbine shaft having an impeller provided in each of the two ends of the shaft; and a relief groove which is formed in the opposed surface of the shaft and includes a front wall surface 20a positioned on front side in the shaft rotation direction, and a rear wall surface 20b positioned on back side in the shaft rotation direction. The inner side in the shaft diameter direction of the rear wall surface is positioned on the more back side in the shaft rotation direction than the end portion 20c of the rear wall surface in the shaft rotation direction.SELECTED DRAWING: Figure 3 |
