PISTON FOR INTERNAL-COMBUSTION ENGINE

摘要

PURPOSE:To facilitate casting while to improve the cooling effect by forming the rear face at the piston top wall section as a rotary face inclined from the central portion toward the circumferential section while projecting a shelf section from the innercircumference of rear face toward the central portion. CONSTITUTION:The rear face 5 at the inner space side of the piston top wall section 2 is formed as a rotary face inclining from the central portion toward the circumferential section of piston. Two pair of shelf sections 7, 8 are provided at the inner circumferential section of piston while facing each other at the positions separated in the axial direction from the rear face 5 of the top wall section 2. The shelf sections 7, 8 are projected from each innercircumferential edge toward the central portion of piston where the shelf section 7 is provided from the boss section 3 for piston pin.