| 摘要 |
PURPOSE:To increase a cooling effect of a pin boss part, by forming a deep combustion part to a piston crown, providing cooling oil passages respectively in the peripheral part of said combustion part and between said peripheral part and an upper wall of the pin boss part and supplying cooling oil to these passages. CONSTITUTION:A deep combustion part 3 is formed to a piston crown 2, and the first cooling oil passage 11 is partitioned by horizontal walls 8 spread from a bottom wall 4 of said part 3 to an internal wall surface 7 of a ring land 6. While the second cooling oil passage 14 is partitioned by an upper wall surface 13 of a pin boss 5 and the bottom wall 4 or the horizontal wall 8, and the both passages are connected through an outlet 15 of the first cooling oil passage 14. Cooling oil, fed through a cooling oil jet flow inlet 17 of the first cooling passage, cools the peripheral part of the deep combustion part, and then reaches the second cooling oil passage 14 thrugh the outlet 15 to surely cool a bearing part of the pin boss. |
