Abstract: A first fitting portion is coupled to a protruding end of the crankshaft to be rotatable about a crankshaft rotational axis. An intermediate member includes a first hole wall slidably supporting the first fitting portion in a first direction orthogonal to the crankshaft rotational axis so that the intermediate member rotates together with the crankshaft. An inner rotor includes a second hole wall slidably supporting the second fitting portion in a second direction orthogonal to the first direction and the crankshaft rotational axis so that the inner rotor rotates together with the intermediate member. One of the first direction and the second direction is in parallel with a line segment joining the crankshaft rotational axis and an axis of a crankpin of the internal combustion engine which is closest to the protruding end of the crankshaft.

Abstract: Disclosed is a piston cooling device wherein the cooling efficiency of a piston is improved by oil injected from an oil jet and supplied to a cooling passage provided in the piston, and the amount of cooling oil is reduced when an internal combustion engine is operated at maximum output. The piston cooling device is provided with a piston for an internal combustion engine, in which a circumferential passage and a cooling passage having an inlet passage and an outlet passage are provided, and an oil jet for injecting oil from an injection port to the inlet passage. The oil jet injects oil at every stroke of the piston so that a two-phase plug flow composed of gas and oil is formed in the cooling passage at least when an internal combustion engine is operated at maximum output.

Abstract: Disclosed is a piston cooling device wherein the cooling efficiency of a piston is improved by oil injected from an oil jet and supplied to a cooling passage provided in the piston, and the amount of cooling oil is reduced when an internal combustion engine is operated at maximum output. The piston cooling device is provided with a piston for an internal combustion engine, in which a circumferential passage and a cooling passage having an inlet passage and an outlet passage are provided, and an oil jet for injecting oil from an injection port to the inlet passage. The oil jet injects oil at every stroke of the piston so that a two-phase plug flow composed of gas and oil is formed in the cooling passage at least when an internal combustion engine is operated at maximum output.

Abstract: A cylinder block as a main part of an engine block includes a cylinder barrel assembly block, a skeleton-like frame surrounding the outer periphery of the cylinder barrel assembly block and a plate-like rigid film member, within a fluid passage in the skeleton-like frame. The skeleton-like frame is integrally joined to the outer surfaces of left and right side walls of the assembly block along the crankshaft axis and includes crossbeam bone members, longitudinal beam bone members and post bone members which are rigid and unitarily assembled into a three-dimensional latticework structure. A cylinder head is integrally coupled to the deck surface of the cylinder block and a lower case is integrally coupled to the lower surface of the cylinder block, lateral outer surfaces of the block and lower case along the crankshaft axis being formed flush with each other in parallel with the cylinder bore axis.