| 摘要 |
PROBLEM TO BE SOLVED: To enhance the impact resistance of a piston head part in a piston having the piston head fixed to a piston body by constituting the piston head so as to fit a cylinder ring land part to the circumference of a top land part through an expansion spring and supporting it by a back-up spring. SOLUTION: A vertical water-cooled diesel engine has this heat insulation type piston 2 fitted to a cylinder block 1. The heat insulation type piston 2 is formed of a piston body 20 having a skirt part 21 and a pin boss part 23 integrally formed thereon and a piston head part 24 fixed to the piston body 20. The piston head 24 is constituted by fitting a cylindrical ring land part 26 formed of a ceramic material to the circumference of a top land part 24 through an expansion clearance 27 and interposing a plurality of pairs of back-up springs 31, 31 in the expansion clearance 27. According to this, the impact resistance of the piston head 24 can be enhanced while suppressing the dispersing heat releasing from the ring land part 26 through a piston ring.
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