| 摘要 |
PURPOSE:To prevent an oscillating phenomenon, scarf abrasion and the like, by forming a crown section and a skirt section, independently from each other, then by coupling them with the use of a rib through the intermediary of a pin boss section so that they are formed in one unit body, and by reducing the wall thickness of an apex section extending from the crown section to at least a first piston ring. CONSTITUTION:A crown section 1 and a skirt sections 2 are coupled with each other through a pin boss section 4 integrally incorporated with the skirt section 4 and a rib 5. Accordingly, the quantity of heat transmitted from the crown section 1 to the skirt section 2 is also reduced so that the gap between the skirt section 2 and the associated cylinder bore may be made smaller, and therefore, the attitude of a piston is stabilized, resulting in that it is possible to reduce slap and noise. Further, a gouge 9 is formed in the upper section of inner peripheral surface of the crown section 1 or slits are formed in the apex section over the entire circumference thereof. Thus, it is possible to restrain the transmission of heat from the crown section so that the temperature of the piston ring groove may be lowered, thereby it is possible to enhance the wear-resistance of a piston ring and the piston groove section. |
