| 摘要 |
PROBLEM TO BE SOLVED: To provide a piston minimizing its height, and a configuring method of the piston.SOLUTION: A piston is equipped with a bottom portion, and a top portion fixed to the bottom portion. The top portion has the uppermost surface, and annular inside and outside upper joint surfaces are suspended from the uppermost surface. The bottom surface has a pair of pin bosses having pin bores aligned along pin bore shafts, a pair of annular inside and outside lower joint surfaces extending upward, and a combustion tray wall. Inside and outside welding joint portion fix the inside and outside upper joint surfaces and lower surfaces with each other. Annular cooling passages are formed in a lateral direction between the upper joint surfaces and the lower joint surfaces. The inside welding joint portion for welding the top portion to the bottom portion is positioned in the combustion tray wall. |
