| 摘要 |
PROBLEM TO BE SOLVED: To improve flexural rigidity and heat radiating performance of a crown face supported to piston pin boss parts by forming ribs on the back face of a piston crown face so as to connect the parts close to the outer periphery of the crown face almost at the center in a piston pin direction and the roots of the piston pin boss parts on the back face of the crown face. SOLUTION: This piston for an internal combustion engine is provided with a skirt 2 hanging over the whole periphery of the piston. A thermal expansion absorbing ring 8 for absorbing the thermal expansion of a crown face 1 in the radial direction of the piston is mounted in a dividing groove 3 provided at the upper face of the piston so as to divide the skirt 2 and the crown face 1 over the whole periphery, and the skirt 2 is connected to piston pin bosses 4 by skirt connecting stays 9. In such a piston, pin-boss ribs 10 are formed on the back face of the piston crown face 1 so as to connect the parts close to the outer periphery of the crown face 1 almost at the center in a piston pin direction and the roots of the piston pin bosses 4 on the back face of the crown face 1. Flexural rigidity and heat radiating performance of the crown face 1 are thereby improved.
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