| 摘要 |
PURPOSE:To make the return of lubricating oil to the oil pan smooth by providing an oil return pumpting means at least in one of oil return paths which connect a crank chamber and a cam chamber to the oil pan of an internal- combustion engine in which the crank shaft is vertically arranged. CONSTITUTION:In the case of embodying the invention in an outboard engine equipped with a pair of top and bottom cylinders horizontally to a cylinder case 20, a lubricating oil pump 33 provided at the bottom face of a cylinder head 22 is operated by the rotation of a cam shaft 32. The lubricating oil pump 33 consists of a main trochoidal pump unit which includes a main inner rotor and a main outer rotor, and a sub-trochoidal pump unit which includes a sub-inner rotor and a sub-outer rotor. The main pump unit absorbs the lubricating oil in an oil pan 48 through a suction pipe 50 and an oil path 49 and supplies the oil to each sliding portion of the engine through oil paths 52, 53, etc. and at the same time, the sub-pump unit absorbs the return oil from the cam chamber 31 through a suction path 63 and returns the oil to the oil pan 48 through a discharge path and oil return path 65. |
