| 摘要 |
<P>PROBLEM TO BE SOLVED: To appropriately cool a plurality of pistons of a vertical engine while minimizing the required quantity of oil. <P>SOLUTION: Two upper cylinders 17 of a cylinder block 11 of the four-cylinder vertical engine are provided with oil jets 118 for jetting oil to the back faces of two pistons fitted into the cylinders 17. Consequently, even if pistons in the lower positions are more effectively cooled by the oil falling by gravity through oil return holes 11s provided in journal support walls 11r, the pistons in the upper positions are forcibly cooled by the oil jetted from the oil jets 118, to uniformly cool four pistons to prevent the occurrence of insufficient cooling or excessive cooling while minimizing the required quantity of oil. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
