Floating bush bearing device and turbocharger provided with the bearing device

Abstract

An object is to provide a floating bush bearing device including a circumferential groove over the entire circumference of an outer peripheral surface of a floating bush while ensuring that a pressing force is applied by lubricant oil to the floating bush to reduce oscillation, as well as a turbocharger provided with the bearing device. A floating bush bearing device includes: a rotary shaft disposed rotatably inside a bearing hole of a casing; a floating bush surrounding the rotary shaft; an oil-feed hole of lubricant oil having an opening on an inner peripheral surface of the bearing hole; a plurality of communication holes formed on the floating bush, each extending between an inner peripheral surface and an outer peripheral surface of the floating bush, and disposed at intervals in a circumferential direction of the floating bush; and a circumferential groove formed on the outer peripheral surface of the floating bush or the inner peripheral surface of the bearing hole and extending over an entire circumference of the outer peripheral surface of the floating bush or the inner peripheral surface of the bearing hole, the circumferential groove passing through openings of the plurality of communication holes or facing the openings of the plurality of communication holes. The circumferential groove has a cross-sectional area which varies in accordance with a circumferential position.