| 摘要 |
PURPOSE:To improve durability of a piston by screwing integrally into a piston main body a combustion chamber inlet peripheral member which is arranged at the top portion of the piston. CONSTITUTION:In forming a combustion chamber 11 at the top portion of a piston, a combustion chamber inlet peripheral member 16 is formed separately from a piston main body 14, and the both are connected together by a screw 15. Unlike other fixing means, the screw connection provides both thermal and mechanical insulation; therefore, even with the piston in cooled condition during when the engine is off operation, stresses are shielded by the screw portion 15, the effect of the piston main body 14 is cut off, and tensile stress generated will be faint. In addition, the mechanical stress generated in the combustion chamber inlet peripheral portion because of the explosion pressure being received at the piston top face and supported by a piston pin boss portion is insulated by the screw portion 15 and is not transmitted to the inlet peripheral portion. Thus, the fatigue limit to repeated stress can be elongated and the durability of the piston can be improved. |
