| 摘要 |
PROBLEM TO BE SOLVED: To provide a piston reducing a deviation of bearing pressure of each skirt to a cylinder wall surface and reducing a bearing pressure load to reduce friction.SOLUTION: A piston 1 made of an aluminum alloy material includes a crown 7 defining a combustion chamber; a pair of arcuate skirts 8, 9 on a thrust side and an anti-thrust side that are provided integrally with the crown and slide on the cylinder wall surface 3; and a pair of curved apron parts 11, 12 connected to both side ends in the circumferential direction of the respective skirts through connection portions 10 and having pin bosses 13, 14. Each connection portion is formed in arc shape in its inner peripheral part and outer peripheral part and is continuously formed such that its radius of curvature is gradually larger from upper ends 16a, 17a toward lower ends 16b, 17b and that its wall thickness is gradually thicker from the upper ends toward the lower ends. |
