Patent ID: 7412958

Claim:
An internal combustion engine comprising: a cylinder block having a plurality of cylinders; a plurality of pistons with one of the pistons being slidable disposed in one of the cylinders to move between a top dead center and a bottom dead center, each of the pistons including a piston pin; a crankshaft disposed below the cylinders and extending in a direction in which the cylinders are arranged, the crankshaft including a plurality of journals and a plurality of crankpins disposed between adjacent pairs of the journals; a plurality of crankshaft bearings rotatably supporting the crankshaft on the cylinder block via the journals; and a piston-crank mechanism linking the crankshaft and the pistons together by the crankpins and the piston pins, the piston-crank mechanism being configured and arranged such that an upward inertia force is produced near the top dead center of each of the pistons that is smaller than a downward inertia force produced near the bottom dead center of the pistons, at least one but less than all of the crankshaft bearings being disposed between an adjacent pair of the cylinders, the adjacent pair of the cylinders having a relationship in which one of the pistons in one of the adjacent pair of the cylinders is near the top dead center when the other of the pistons in the other of the adjacent pair of the cylinders is near the bottom dead center, and the at least one but less than all of crankshaft bearings having a higher rigidity than remaining ones of the crankshaft bearings.