| 摘要 |
<p>PURPOSE:To reduce friction loss in a valve system of an engine, and solve the problems such as power loss and abrasion-resistance by specifying hardness difference between a cam and an adjusting shim, and also specifying relation between mutual surface roughness and minimum oil film thickness. CONSTITUTION:In a valve system of an engine, an intake/exhaust valve 5 is opened or closed by means of a cam 2 through a valve lifter 3. Hardness of an adjusting shim 4 which adjusts a valve clearance is larger than that of the cam 2 at their contact surfaces, by 300kg/mm<2> in Vickers hardness. A simple square, mean at the mutual surface roughnesses is set in respect to a minimum oil film thickness formed between the cam 2 and the shim 4 in the case of engine speed ranged between 1000 to 5000rpm, so as to satisfy the following expression: 1<=(Rc<2>+Ra<2>)1/2hmin<=8, where Rc: an initial surface roughness of the cam, Ra: an initial surface roughness of the shim, and hmin: the minimum oil film thickness.</p> |
