| 摘要 |
PURPOSE:To enhance the strength of the top section of a piston without increasing the wall thickness of the top section, by forming the upper section of a piston body with a rapid-cooled and solidified aluminum powder alloy, and as well by forming an oil gallery in the vicinity of a piston ring groove. CONSTITUTION:A piston body 11 is composed of an upper section 14 including therein a piston ring groove 12 and a piston top section 13, and a lower section 17 including a skirt section 14 and a piston boss section 16. With the above-mentioned arrangement, the upper section 14 is made of a rapid-cooled and solidified aluminum powder alloy, and the lower section 17 is made of, for example, usual alluminum alloy cast. Further, both of them 14, 17 are integrally jointed together by electron beam welding 20, and with this jointing an oil gallery 21 is formed in the vicinity of piston ring grooves 12, 18. This oil gallery 21 is a passage for cooling oil which cools the vicinity of the piston ring grooves 12, 18 and the piston top section 13. |
