Abstract: A vapor chamber includes a body sheet, and a first sheet stacked on the body sheet. The body sheet includes a vapor flow channel portion through which vapor of a working fluid flows and a liquid flow channel portion which is in communication with the vapor flow channel portion and through which liquid of the working fluid flows. The vapor flow channel portion includes a vapor passage extending in a first direction. The first sheet includes a first sheet inner surface facing the body sheet and a first sheet groove provided in the first sheet inner surface. The first sheet groove is provided at a position of overlapping with the vapor passage in a plan view and extends in a direction intersecting with the first direction.

Abstract: A hot wheel of a turbocharger formed by precision casting, including a shaft-shaped hub part disposed at a radially central portion thereof; a plurality of vane parts formed on a periphery of the hub part; an wrench boss formed at a top end of the hub part; and a boss portion formed at a bottom end of the hub part. In the hot wheel having the above-described construction, with an outer configuration of a necessary portion of each of the hub part, the wrench boss, and the boss portion maintained, a cavity open outward is formed at a radially central portion of the hub part with the cavity symmetrically penetrated through the wrench boss.