Daido Metal Company Ltd.

Shigeyoshi Mori

Kwangik Na

Tadatoshi Nagasaki

Motohira Yamada

Tomoyasu Shiroya

A ball socket structure is provided, which includes a ball portion and a socket portion, the ball portion and the socket portion being configured to slide against one another, in which the socket portion includes a sliding surface including a PVD coating layer, the sliding surface of the socket portion is a concave spherical surface, and a value (Ds/Rs) of a ratio between a depth Ds of the sliding surface and a radius of curvature Rs of the sliding surface is from 0.05 to 0.70.

Ball socket structure

A cooling portion has an air inlet into which cooling air flows and is positioned in a preset range. When a distance from the upper to lower ends of an oil chamber in the axial direction of a rotating shaft member is h, and the shortest distance between an outer peripheral face of a casing and an inner peripheral face of a cover is a, the preset range is set in the following manner. Specifically, the preset range is set between &#xbc;h upward and 5/4h downward relative to the upper end of the oil chamber as a reference point, in the axial direction of the rotating shaft member. Additionally, the preset range is set between the outer peripheral face of the casing and relative to the outer peripheral face of the casing as a reference point, in the radial direction of the rotating shaft member.

Vertical bearing device

When an annular portion of a thrust collar rotates together with a rotating shaft member, centrifugal force and shear force, or differential pressure caused by difference in flow rate are generated in lubricating oil in a circulation oil chamber. With this, the lubricating oil in the circulation oil chamber is guided from the inner peripheral side to the outer peripheral side of the annular portion, through a circulation hole penetrating the annular portion. The flow of lubricating oil guided by the circulation hole forms a flow of lubricating oil from a lower oil chamber to an upper oil chamber through the circulation oil chamber. As a result, the lubricating oil stored in the lower oil chamber is circulated to the upper oil chamber through the circulation oil chamber, by rotation of the thrust collar.

A lubricating oil passage portion that constitutes a cooling portion is exposed to the outside from a casing. Lubricating oil having absorbed heat of a thrust bearing portion and a journal bearing portion is cooled in the cooling portion, when the lubricating oil moves from an upper oil chamber to a lower oil chamber while circulating by use of gravity. Thus, the circulating lubricating oil prompts cooling of the heated thrust bearing portion and journal bearing portion. Additionally, the lubricating oil passage portion of the cooling portion is provided integrally with the casing, on the radially outer side of the casing.

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Inuyama, Japan

Shigeyoshi Mori