| 摘要 |
A lubrication structure of a cam shaft equipped with a variable valve timing is provided to prevent damage of a journal part of the cam shaft and prevent sticking caused due to breaking of a lubrication film. A cam shaft(100) has one end to be fitted into a continuously variable valve timing(10) equipped with a sprocket(12), and an advance hole(112) having an advance channel(110) formed in the cam shaft is formed adjacently to the sprocket. A retard hole(122) is spaced apart from the advance hole, and has a retard channel(120) formed in the cam shaft. A branch channel(200) is formed on a mounting portion(2a) of a cylinder head(2). The branch channel has one end which surface-contacts the cam shaft and is communicated to a retard hole(122') formed on the mounting portion of the cylinder head having a slide surface(2b), and the other end which passes through a counter bore(2c) and is communicated to the slide surface on which the cam shaft is mounted. The branch channel serves to prevent a lubrication film from being broken by the load applied by the sprocket connected to the cam shaft during idle or cold start of an engine.
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