Cooling system of liquid-cooled multicylinder engine

Abstract

A cooling system of a liquid-cooled multicylinder engine of the two cycle type, wherein a crank shaft is journalled by bearings housed in bearing housings of a small diameter mounting therein airtight seal members as well as the bearings and located at opposite end portions and an intermediate portion of a crank case consisting of upper and lower members, cylinders are arranged on the upper end surface of the upper crank case member, and each cylinder has a suction conduit attached to one side thereof and an exhaust conduit attached to the other side thereof, includes a centrifugal pump driven by the crank shaft for circulating a cooling liquid and located in a recess on the suction side of the crank case between cylinders, with the axis of the pump being parallel to the crank shaft. The centrifugal pump is formed at its lower end portion with a pump outlet extending substantially horizontally and connected to a suction side inlet of a liquid passage extending along the underside and the exhaust side of the bearing housing in the intermediate portion of the crank case, and a liquid jacket communicating with the liquid passage is mounted on the entire exhaust side portion of the upper crank case member and has an upper outlet connected to another liquid jacket in each of the cylinders at the interface between the crank case and the cylinders.