Piston assembly for an internal combustion engine of a motor vehicle

A piston assembly for a cylinder of an internal combustion engine of a motor vehicle, the piston assembly comprising:

• a piston head adapted to reciprocate along a longitudinal axis within the cylinder, wherein the piston head comprises:
• an outer diameter surface spaced a first distance from a longitudinal axis;
• an annular surface spaced a second distance from the longitudinal axis with the second distance being less than the first distance;
• and
• upper and lower walls each extending between the annular surface and the outer diameter surface so as to define an annular groove in the outer diameter surface;
• and
• a piston ring received within the annular groove, wherein the piston ring comprises:
• a peripheral surface spaced a third distance from the longitudinal axis, with the third distance being longer than the first distance such that the peripheral surface is adapted to slide against a wall of the cylinder in response to the piston head reciprocating along the longitudinal axis;
• an inner diameter surface facing the annular surface of the piston head;
• and
• top and bottom surfaces each extending between the peripheral surface and the inner diameter surface to define a wall thickness;
• wherein the inner diameter surface of the piston ring and the annular surface of the piston head cooperate with one another to define a plurality of pockets angularly spaced from one another about the longitudinal axis and configured to receive oil;
• wherein the annular surface is a continuously concave surface extending about the longitudinal axis.

A piston assembly for a cylinder of an internal combustion engine of a motor vehicle, the piston assembly comprising:

• a piston head adapted to reciprocate along a longitudinal axis within the cylinder, wherein the piston head comprises:
• an outer diameter surface spaced a first distance from a longitudinal axis;
• an annular surface spaced a second distance from the longitudinal axis with the second distance being less than the first distance;
• and
• upper and lower walls each extending between the annular surface and the outer diameter surface so as to define an annular groove in the outer diameter surface;
• and
• a piston ring received within the annular groove, wherein the piston ring comprises:
• a peripheral surface spaced a third distance from the longitudinal axis, with the third distance being longer than the first distance such that the peripheral surface is adapted to slide against a wall of the cylinder in response to the piston head reciprocating along the longitudinal axis;
• an inner diameter surface facing the annular surface of the piston head;
• and
• top and bottom surfaces each extending between the peripheral surface and the inner diameter surface to define a wall thickness;
• wherein the inner diameter surface of the piston ring and the annular surface of the piston head cooperate with one another to define a plurality of pockets angularly spaced from one another about the longitudinal axis and configured to receive oil;
• wherein the piston ring further comprises an upper chamfered corner positioned between the top side surface and the inner diameter surface and a lower chamfered corner positioned between the bottom side surface and the inner diameter surface.