Crosshead piston

Claim 1

An oil cooled crosshead type piston assembly for a an internal combustion engine, said assembly comprising: a head member having a crown section integrally formed with an outer ring belt section and an inner piston pin connecting section, both depending from said crown section, said piston pin connecting section including a saddle portion having a centrally disposed opening to permit the passage of cooling oil into the crown and ring belt sections, a downwardly facing cylindrical recess for receiving and transmitting loads to a piston pin and a pair of piston pin receiving arms extending downwardly from opposite ends of said saddle portion, said arms having opposed pin encircling openings disposed coaxially with said recess; a separately formed skirt member including a generally cylindrical wall extending downwardly from adjacent said ring belt section, said skirt member having a pair of oppositely disposed bosses extending inwardly of said wall and having pin receiving openings extending therethrough and aligned with the pin encircling openings in said head member arms so as to receive a piston pin for retaining said head and skirt portions in assembly; said skirt member being closely fitted with the saddle portion of said pin connecting section so as to control oil drainage from the piston undercrown cavity; said head member having an annular reduced diameter portion of said ring belt section which is received internally of the upper end of said skirt cylindrical wall to form inner and outer concentric portions having respectively inner and outer opposed cylindrical surfaces; a seal groove in one of said concentric portions and opening through one of said surfaces; and a seal ring in said groove and engaging the other of said surfaces so as to prevent excessive leakage of cooling oil between said head and skirt members from the interior to the exterior of said piston assembly.