Tpr Co., Ltd.

Yushi Abe

Akira Hikone

Naoki Umeda

Kenichiro Kosaka

Satoshi Minemura

Masayuki Ohira

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

An outer peripheral surface of a piston ring has a cut surface provided to form a cutout portion between an outer peripheral end portion and a lower surface, the cut surface includes a curved concave surface, an inclination angle of a tangent of the curved concave surface at a point closest to the combustion chamber side on the curved concave surface, with respect to a first virtual line extending in parallel to the lower surface is equal to or greater than 5° and equal to or less than 50°, and in a case where an axial direction width of the piston ring is set as h1, and an axial direction width of the cut surface is set as H, H/h1 is equal to or greater than 0.2 and equal to or less than 0.4.

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Tokyo, Japan

Yushi Abe