| 摘要 |
PROBLEM TO BE SOLVED: To efficiently cool pistons and suppress their deformation by improving their strength, while reducing their weight. SOLUTION: A piston 1 has a coupling member integrated with a piston crown portion 6 and with a pin boss portion 7 to interconnect them. The piston 1 has a circumferentially extending annular groove 14 on the inner side of a ring land portion 5 and in proximity to a piston ring groove 4. The coupling member has rib members 8, radially arranged around a piston center axis L2 in a peripherally coupled relationship with the internal surface of the ring land portion 5, and through-holes 15 cut in the rib members 8 corresponding to the annular groove 14.
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