Abstract: An opposed-piston engine includes: a cylinder having a scavenging port on one side in an axial direction and an exhaust port on another side in the axial direction, a scavenging-side piston disposed inside the cylinder on the one side in the axial direction, an exhaust-side piston disposed inside the cylinder on the other side in the axial direction; and at least one fuel injection device configured to inject fuel between the scavenging-side piston and the exhaust-side piston inside the cylinder. A top surface of the exhaust-side piston is formed in a flat shape, a top surface of the scavenging-side piston has a scavenging-side cavity with a predetermined cavity volume, and the at least one fuel injection device includes at least one scavenging-side fuel injection device having a central axis inclined to the one side in the axial direction toward an inner side in a radial direction of the cylinder.

Abstract: An opposed-piston engine includes: a cylinder; a one-side piston disposed inside the cylinder on one side in an axial direction; and an other-side piston disposed inside the cylinder on another side in the axial direction. Atop surface of the one-side piston has a one-side cavity recessed in a central portion. A top surface of the other-side piston has an other-side cavity recessed in a central portion. An outer peripheral edge of the one-side cavity is at least 0.1D1 away from an outer peripheral edge of the top surface of the one-side piston over the entire circumference, where D1 is a diameter of the top surface of the one-side piston. An outer peripheral edge of the other-side cavity is at least 0.1D2 away from an outer peripheral edge of the top surface of the other-side piston over the entire circumference, where D2 is a diameter of the top surface of the other-side piston.

Abstract: A piston of an internal combustion engine configured to be reciprocable along an axial direction in a cylinder includes a cavity formed to be recessed in a center of a piston top surface, and an outer circumferential edge portion located on a radially outer side of the cavity in the piston top surface. The cavity includes a lip portion, a raised portion, and a curved portion. The curved portion includes an outer circumference-side curved surface which includes a curved surface connected to the lip portion, an inner circumference-side concave surface which is located on a radially inner side of an outer circumference-side curved surface and includes a surface connected to a raised portion, the inner circumference-side concave surface including a deepest portion of the cavity, and a convex surface formed between the outer circumference-side curved surface and the inner circumference-side concave surface, as well as protruding upward.

Abstract: The purpose of the present invention is to provide a gas engine and a ship provided with the same, the gas engine making it is possible to ensure a distance that enables fuel and an oxidizing agent to mix, and to evenly mix the oxidizing agent and the fuel even if the flow rate of gas traveling towards intake pipes varies. A gas engine (1) comprises: an intake passage (10) through which a gas flows; a plurality of intake pipes (12A, 12B) where the intake passage (10) branches apart at a branching section (14) that is downstream in the gas flow direction, the intake pipes opening to a cylinder (16) at the downstream end; and a fuel injection means (31) that injects fuel into the intake passage (10). The fuel injection means (31) is provided upstream of the branching section (14) in the gas flow direction, and injects varying quantities of fuel into the plurality of intake pipes (12A, 12B).

Abstract: A piston of an internal combustion engine configured to be reciprocable along an axial direction in a cylinder includes a cavity formed to be recessed in a center of a piston top surface, and an outer circumferential edge portion located on a radially outer side of the cavity in the piston top surface. The cavity includes a lip portion which has an inclined surface extending obliquely downward from the outer circumferential edge portion toward a radially inner side, a raised portion protruding upward from a bottom of the cavity, and a curved portion connecting the raised portion and the lip portion.

Abstract: The purpose of the present invention is to provide a gas engine and a ship provided with the same, the gas engine making it is possible to ensure a distance that enables fuel and an oxidizing agent to mix, and to evenly mix the oxidizing agent and the fuel even if the flow rate of gas traveling towards intake pipes varies. A gas engine (1) comprises: an intake passage (10) through which a gas flows; a plurality of intake pipes (12A, 12B) where the intake passage (10) branches apart at a branching section (14) that is downstream in the gas flow direction, the intake pipes opening to a cylinder (16) at the downstream end; and a fuel injection means (31) that injects fuel into the intake passage (10). The fuel injection means (31) is provided upstream of the branching section (14) in the gas flow direction, and injects varying quantities of fuel into the plurality of intake pipes (12A, 12B).

Abstract: An exhaust gas recirculation apparatus includes: a fresh air throttle portion that continues from a fresh air inlet portion and is configured to throttle the flow of fresh air; an inner side tube portion that continues from the fresh air throttle portion, has a tubular shape and has an opening end disposed on a side opposite to the fresh air throttle portion; an exhaust gas inlet portion configured to receive a flow of exhaust gas; a surrounding portion that continues from the exhaust gas inlet portion, surrounds the inner side tube portion, and defines a circumference direction flow path for the exhaust gas extending along an outer circumference surface of the inner side tube portion; and an outlet portion that continues from the surrounding portion, has a tubular shape, and defines a merging flow path configured to receive the flow of the fresh air flowing out from the opening end of the inner side tube portion and the flow of the exhaust gas flowing out from the circumference direction flow path.

Abstract: An exhaust gas recirculation apparatus includes: a fresh air throttle portion that continues from a fresh air inlet portion and is configured to throttle the flow of fresh air; an inner side tube portion that continues from the fresh air throttle portion, has a tubular shape and has an opening end disposed on a side opposite to the fresh air throttle portion; an exhaust gas inlet portion configured to receive a flow of exhaust gas; a surrounding portion that continues from the exhaust gas inlet portion, surrounds the inner side tube portion, and defines a circumference direction flow path for the exhaust gas extending along an outer circumference surface of the inner side tube portion; and an outlet portion that continues from the surrounding portion, has a tubular shape, and defines a merging flow path configured to receive the flow of the fresh air flowing out from the opening end of the inner side tube portion and the flow of the exhaust gas flowing out from the circumference direction flow path.