| 摘要 |
A piston assembly includes: a piston skirt; and a piston crown formed by a casting method and coupled to an upper portion of the piston skirt by using a stud bolt, wherein oil galleries are formed between an upper wall of the piston skirt and an upper wall of the piston crown, wherein an annular part having a circular ring shape and a plurality of ribs having a linear shape and radially arranged to form oil channels for flowing cooling oil are formed on the upper wall of the piston crown, and the plurality of ribs are divided into outer ribs and inner ribs by the annular part. |
