Nippon Piston Ring Co., Ltd.

Kazumi Moroi

Mitsuru Urabe

Hirokazu Murata

Jyuta Tase

Kazuhiko Kanno

In a sliding structure for an internal combustion, a cylinder has recesses in a stroke center region. Piston rings have inclined surfaces on an outer circumferential surface, and a lubricating oil flows between the inner wall surface and the outer circumferential surface that relatively move via the inclined surfaces. At any RPM equal to or greater than at idle, a center friction coefficient at the stroke center region through which the piston rings pass at the highest speed is less than a center friction coefficient when no recesses are formed in the stroke center region. Contrarily, at the RPM, an outside friction coefficient when the piston rings pass through a region outside the stroke center region is less than an outside friction coefficient when the recesses are formed in the outside region. As a result, further improved low fuel efficiency is achieved for the dimple liner technique.

Sliding structure for internal combustion engine, method for controlling idling operation, and method for controlling operation of internal combustion engine

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Saitama, Japan

Kazumi Moroi