The present disclosure provides an open-faced piston with a circumferential groove into which a piston ring assembly is arranged. Openings at the bottom of the circumferential groove and between a front land of the open-faced piston and the piston face are provided. The openings are arranged to allow for a combustion reaction to propagate through the volume defined between the bottom of the piston ring assembly and the piston face such that at least a portion of an air and fuel mixture located in that volume is reacted.

The present disclosure provides an open-faced piston with a circumferential groove into which a piston ring assembly is arranged. Openings at the bottom of the circumferential groove and between a front land of the open-faced piston and the piston face are provided. The openings are arranged to allow for a combustion reaction to propagate through the volume defined between the bottom of the piston ring assembly and the piston face such that at least a portion of an air and fuel mixture located in that volume is reacted.

A joining support jig includes: a cylinder support for supporting a cylinder; an annular body support for supporting an annular body; and a plurality of movable members that can approach or separate from the cylinder. Each of the plurality of movable members extends from the cylinder side to the annular body side and across an abutment surface between the cylinder and the annular body in the thickness direction of the movable member. Further, the movable members are each formed with a gas supply groove that is depressed in the direction away from the cylinder and has an opening opposing the abutment surface.

A joining support jig includes: a cylinder support for supporting a cylinder; an annular body support for supporting an annular body; and a plurality of movable members that can approach or separate from the cylinder. Each of the plurality of movable members extends from the cylinder side to the annular body side and across an abutment surface between the cylinder and the annular body in the thickness direction of the movable member. Further, the movable members are each formed with a gas supply groove that is depressed in the direction away from the cylinder and has an opening opposing the abutment surface.

A piston ring includes a first ring portion which is fitted onto an outer circumferential portion of a piston and which is capable of sliding relative to an inner wall surface of a cylinder, and a second ring portion which is fitted onto the outer circumferential portion of the piston, arranged side-by-side with the first ring portion in the axial direction, and which is capable of sliding relative to the inner wall surface of the cylinder. The second ring portion is fitted onto the outer circumferential portion of the piston in such a way as to be positioned on a side opposite to a compression chamber inside the cylinder, relative to the first ring portion, and has a greater hardness than the first ring portion has.

Embodiments of a combination piston and piston ring reduce the volume of a crevice defined between the circumferential wall of a cylinder and a portion of the outer wall of a piston within the cylinder, the portion extending down from the top of the piston. The combination piston and piston ring is configured such that pressurized fluid within the cylinder reliably urges a radial face of the piston ring to sealingly engage the circumferential wall of the cylinder, even as the piston reciprocates within the cylinder.

Embodiments of a combination piston and piston ring reduce the volume of a crevice defined between the circumferential wall of a cylinder and a portion of the outer wall of a piston within the cylinder, the portion extending down from the top of the piston. The combination piston and piston ring is configured such that pressurized fluid within the cylinder reliably urges a radial face of the piston ring to sealingly engage the circumferential wall of the cylinder, even as the piston reciprocates within the cylinder.

A piston for an internal combustion engine may include a piston head, an encircling fire land, and at least one annular groove structured to receive a piston ring and disposed contiguous to the fire land. The piston may include a first fire land portion having a first axial height h1, a second fire land portion having a second axial height h2, and a third fire land portion having a third axial height h3. The first fire land portion may have an upper external diameter D1. The third fire land portion may have a lower external diameter D3. A transition from the first to the second fire land portion may have a first external diameter D12. A transition from the second to the third fire land portion may have a second external diameter D23. The relationship (D12D23)/h2>(D23D3)/h3 may apply.

A piston for an internal combustion engine may include a piston head, an encircling fire land, and at least one annular groove structured to receive a piston ring and disposed contiguous to the fire land. The piston may include a first fire land portion having a first axial height h1, a second fire land portion having a second axial height h2, and a third fire land portion having a third axial height h3. The first fire land portion may have an upper external diameter D1. The third fire land portion may have a lower external diameter D3. A transition from the first to the second fire land portion may have a first external diameter D12. A transition from the second to the third fire land portion may have a second external diameter D23. The relationship (D12D23)/h2>(D23D3)/h3 may apply.

The present disclosure provides an open-faced piston with a circumferential groove into which a piston ring assembly is arranged. Openings at the bottom of the circumferential groove and between a front land of the open-faced piston and the piston face are provided. The openings are arranged to allow for a combustion reaction to propagate through the volume defined between the bottom of the piston ring assembly and the piston face such that at least a portion of an air and fuel mixture located in that volume is reacted.