Tpr Co., Ltd.

Ipr Industry Co., Ltd.

Masayuki Ohira

Naoki Umeda

Takashi Sato

Akira Hikone

Seiji Tamaki

Takashi Oizumi

Yushi Abe

An outer circumferential surface of a piston ring has a cut surface forming a notched portion between an outer circumferential end surface and a lower surface, the cut surface including a first surface between the outer circumferential end surface and a bottom portion, and a second surface between the bottom portion and the lower surface. The second surface is inclined away from a central axis of the piston ring as it extends toward a crank chamber side, an angle of inclination of the second surface with respect to the bottom portion being greater than or equal to 50° and less than or equal to 85°. When an axial width of the piston ring is hand a distance in an axial direction between a connecting portion between the cut surface and the outer circumferential end surface and a connecting portion between the cut surface and the lower surface is H, H/his greater than or equal to 0.2 and less than or equal to 0.4.

Piston ring

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.

Cylinder liner and cylinder bore

Growing community of inventors

Tokyo, Japan

Masayuki Ohira