Piston with cooling gallery and closed collar chamber

A piston, comprising:

• a piston crown including radially inner and outer crown mating surfaces, the crown defining at least in part a cooling gallery extending about a periphery of the crown, the crown including a crown collar wall extending downward to a crown collar end;
• and
• a piston skirt, including:
• a pair of oppositely disposed pin bosses configured to receive a connecting rod between the pin bosses;
• a radially inner skirt mating surface abutted along a radially inner interface region with the radially inner crown mating surface;
• a radially outer skirt mating surface abutted along a radially outer interface region with the radially outer crown mating surface such that the cooling gallery is substantially enclosed;
• and
• a skirt collar wall disposed adjacent one of the radially inner and radially outer interface regions and extending upwards to the free end of the crown collar wall;
• wherein the crown collar wall cooperates with the skirt collar wall and the radially inner interface region to enclose an annular gallery to prevent fluid intrusion into the annular gallery;
• and
• wherein a weld flashing extending from an associated pair of crown and skirt mating surfaces adjacent the crown and skirt collar walls is contained within the annular gallery;
• wherein the crown collar wall cooperates with the skirt collar wall by overlapping one another in an unfused joint to enclose the radially inner interface region formed between the radially inner skirt mating surface and the radially inner crown mating surface;
• wherein at least one of the crown collar wall and the skirt collar wall defines an angled end surface, the angled end surface oriented at an oblique angle with respect to a longitudinal axis of the piston.

A method, comprising:

• providing a piston crown including radially inner and outer crown mating surfaces, the crown defining at least in part a cooling gallery extending about a periphery of the crown;
• abutting the inner and outer crown mating surface with corresponding inner and outer skirt mating surfaces of a piston skirt to form a radially inner interface region between the inner mating surfaces, a radially outer interface region between the outer mating surfaces, and a cooling gallery disposed between the radially inner and outer interface regions, the skirt including a pair of oppositely disposed pin bosses defining piston pin bores and cooperating to define a generally open central region configured to receive a connecting rod between the pin bosses;
• forming a crown collar wall extending downward from the crown to a crown collar end;
• providing a skirt collar wall disposed radially inwardly of the radially inner interface region and extending upwards to the free end of the crown collar wall, wherein the crown collar wall cooperates with the skirt collar wall and the radially inner interface region to enclose an annular gallery to prevent fluid intrusion into the annular gallery, and a weld flashing extending from an associated pair of crown and skirt mating surfaces adjacent the crown and skirt collar walls is contained within the annular gallery;
• and
• defining wherein at least one of the crown collar wall and the skirt collar wall defines an angled end surface
• wherein the crown collar wall cooperates with the skirt collar wall by overlapping one another in an unbonded joint to enclose the radially inner interface region formed between the radially inner skirt mating surface and the radially inner crown mating surface.