Patent ID: 7721431

Claim:
A method of making an engine piston comprising forming an outer shell part comprising a crown, centered on a longitudinal axis, and a tubular side wall extending axially with respect to a periphery of the crown to an open end, said crown having at least a peripheral region integral with the side wall; forming a mounting member having an upper member part and opposite thereto gudgeon pin bosses and a periphery dimensioned to fit within and interface with the tubular side wall; disposing the mounting member within the tubular side wall such that the gudgeon pin bosses face the open end, the upper part interfaces with the crown at least a radially extending crown interface defining mutual axial location reference, and the periphery interfaces with the side wall at a wall interface spaced axially from the crown periphery and radially from said radially extending crown interface, defining thereby a transversely extending closure plate closing partly from below a peripheral chamber in the crown; and permanently bonding the mounting member to the shell part at said wall interface and to the crown at a crown bonding interface radially inwardly of said wall interface; wherein said crown includes a combustion bowl having a combustion bowl wall and defining a combustion bowl floor displaced axially of the crown peripheral region by said bowl wall by the mounting member, and wherein said permanently bonding step includes bonding the mounting member to the crown by way of said crown bonding interface between the combustion bowl floor defined by the mounting member and the combustion bowl wall defined by the crown; and defining said crown bonding interface extending in a substantially axial direction accessible from outside of the combustion bowl and bonding the combustion bowl floor to the combustion bowl wall by access through the combustion bowl.