Tpr Co., Ltd.

Tpr Industry Co., Ltd.

Ipr Industry Co., Ltd.

Seiji Tamaki

Takashi Oizumi

Takashi Sato

Naoki Umeda

Kentaro Kawano

Masayuki Ohira

Seeroku Hoshino

Hirofumi Osada

Provided is a cylinder liner which can reduce the friction of the sliding surface from conventional levels and improve fuel efficiency without increasing oil consumption from conventional levels. When the inner circumferential surface of a cylinder liner or cylinder bore used in an internal combustion engine has a first sliding region, a second sliding region, and a third sliding region, and when respective surface roughness Rvk is from 0.05 μm to 0.3 μm, from 0.4 μm to 1.5 μm, and from 0.15 μm to 0.7 μm, a friction can be reduced while maintaining oil consumption.

Cylinder liner and cylinder bore

The present invention addresses the problem of providing a cylinder liner or a cylinder bore, which can reduce not only friction on a sliding surface but also oil consumption. In a piston sliding direction of the cylinder bore, grooves of a second sliding region positioned on the side of crankcase have a higher groove area ratio at a depth of 0.3 &#x3bc;m than grooves of a first sliding region positioned on the side of combustion chamber, and the groove area ratio is in a specific range, whereby friction and oil consumption can be reduced.

Under a state in which the combination oil ring is mounted in an oil ring groove before inserted into a cylinder bore, when an inclined surface of an upper ear portion of an expander spacer is held in contact with an inner peripheral surface of an upper segment and an inclined surface of a lower ear portion of the expander spacer is held in contact with an inner peripheral surface of a lower segment, an upper protrusion amount (P1) from an outer peripheral-side end surface of the expander spacer to an outer peripheral surface vertex of the upper segment is larger than a lower protrusion amount (P2) from the outer peripheral-side end surface of the expander spacer to an outer peripheral surface vertex of the lower segment. When the combination oil ring is inserted into the cylinder bore, the sealing performance can be improved to reduce the oil consumption.

Combination oil ring

Provided is an oil ring. A shape of an outer peripheral surface of an upper segment arranged on an engine combustion chamber side has a symmetrical curved shape. A shape of an outer peripheral surface of a lower segment arranged on a side away from the engine combustion chamber is a symmetrical curved shape.

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Tokyo, Japan

Seiji Tamaki