LUBRICATION SYSTEM FOR FOUR-STROKE ENGINE

摘要

A lubrication system for a four-stroke engine. The engine comprises an oil pan (2) for storing lubricating oil, a crankcase (1), a cam chamber (3), a rocker arm chamber (4), and a distribution chamber (5) for separating an oil-gas mixture into oil mist and liquid oil. In the lubrication system, the oil pan (2) is communicated with the crankcase (1) through an oil supply passage (21). A one-way valve (211) is arranged in the oil supply passage (21). The crankcase (1) is communicated with the distribution chamber (5) through a first oil delivery passage (15). A one-way valve (151) is arranged in the first oil delivery passage (15). The distribution chamber (5) is communicated with the cam chamber (3) through a second oil delivery passage (53). The cam chamber (3) is communicated with the rocker arm chamber (4) through a third oil delivery passage (34).The rocker arm chamber (4) is communicated with the crankcase (1) through at least one (41). A one-way valve (413) is arranged in the oil return passage (41). The lubrication system of the present invention has a simple structure and low emission and manufacturing costs.