Internal combustion engine

摘要

This invention relates to an internal combustion engine including an oil seal ring between a cylinder block and a crank shaft, a crank shaft cap and a conduit. The cylinder block includes a plurality of cylinders, a crank shaft support portion and an oil seal retainer. The crank shaft support portion is located under the plurality of cylinders and the oil seal retainer projects outwardly from the cylinder block. A crank case is defined within the cylinder block. The crank shaft cap is secured to the crank shaft support portion and an opening is defined therebetween. The crank shaft includes a main journal and a flange portion. The main journal is inserted into the opening defined between the crank shaft support portion and the crank shaft cap. The crank shaft is rotatably mounted on both the cylinder block and the crank shaft cap. The flange portion extends outwardly from the main journal and is spaced from the crank shaft support portion and the oil seal retainer of the cylinder block, so that a cavity is defined between the flange portion of the crank shaft, the oil seal retainer, the crank shaft support portion of the cylinder block and the crank shaft cap. The oil seal ring is located between the oil seal retainer of the cylinder block and the outer peripheral surface of the flange portion. The conduit is defined within the crank shaft support portion or the crank shaft cap. The conduit communicates the cavity with the crank case.