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: An opposed-piston engine according to an embodiment is a first fuel injection device configured to inject fuel from a circumferential wall surface of at least one cylinder into the cylinder, and a second fuel injection device disposed to be displaced in a circumferential direction so as to be opposite to the first fuel injection device across an axial center of the cylinder. Each of the first fuel injection device and the second fuel injection device includes a plurality of injection holes having different injection directions, in a cross-section orthogonal to the axial direction. A direction directed by a first downstream injection hole is configured to pass through a second injection region, and a direction directed by a second downstream injection hole is configured to pass through a first injection region.

Abstract: An engine according to an embodiment includes at least one cylinder, at least one piston disposed in the at least one cylinder, a plurality of fuel injection valves disposed on the at least one cylinder, the plurality of fuel injection valves including a first fuel injection valve having a predetermined total hole area and a second fuel injection valve having a total hole area smaller than the total hole area of the first fuel injection valve, and a control device for controlling the first fuel injection valve and the second fuel injection valve according to a load of the engine.

Abstract: An opposed-piston engine according to an embodiment is a first fuel injection device configured to inject fuel from a circumferential wall surface of at least one cylinder into the cylinder, and a second fuel injection device disposed to be displaced in a circumferential direction so as to be opposite to the first fuel injection device across an axial center of the cylinder. Each of the first fuel injection device and the second fuel injection device includes a plurality of injection holes having different injection directions, in a cross-section orthogonal to the axial direction. A direction directed by a first downstream injection hole is configured to pass through a second injection region, and a direction directed by a second downstream injection hole is configured to pass through a first injection region.