REDUCED COMPRESSION HEIGHT DUAL GALLERY PISTON, PISTON ASSEMBLY THEREWITH AND METHODS OF CONSTRUCTION THEREOF

摘要

A piston assembly, piston therefor and methods of construction are provided. The assembly includes a piston head and connecting rod operably coupled thereto via a wrist pin. The piston head has an upper crown with a combustion bowl and an undercrown surface. The lower crown includes axially aligned pin bores receiving the wrist pin. An upper wall of the lower crown has an oil inlet, an oil outlet and a concave, saddle bearing surface that bears against the wrist pin. A toroid-shaped outer cooling gallery is formed between wall portions of the upper and lower crowns, wherein the outer cooling gallery surrounds an inner cooling gallery. The connecting rod is fixed to the wrist pin for conjoint oscillation. The connecting rod has an oil passage in fluid communication with a through hole in the wrist pin to allow oil to flow therethrough into the inner cooling gallery via the oil inlet.

主权项

1. A piston assembly for an internal combustion engine, comprising:
a piston head having an upper crown and a lower crown joined together by an annular outer wall and an annular inner wall, said upper crown having an upper combustion surface and a combustion bowl depending therein with an undercrown surface provided opposite said combustion bowl, said lower crown having an upper wall and a pair of laterally spaced pin bosses depending from said upper wall, said pin bosses having pin bores aligned axially with one another along a pin bore axis, a concave bearing surface formed in said upper wall and extending between said pin bosses to form a continuous bearing surface with said pin bores, a toroid-shaped outer cooling gallery bounded between said annular outer wall and said annular inner wall and an inner cooling gallery bounded by said annular inner wall, said upper wall having at least one oil inlet and at least one oil outlet extending into said inner cooling gallery; a wrist pin having a through hole; and a connecting rod having an end fixed to said wrist pin for conjoint oscillation therewith, said connecting rod having an oil passage aligned for fluid communication with said through hole in said wrist pin and with said oil inlet to allow oil to flow through the connecting rod, through the wrist pin, and through the oil inlet into said inner cooling gallery and outwardly from said inner cooling gallery through said at least one oil outlet.