A piston ring assembly for sealing a cylinder wall to a piston body is provided. The piston ring assembly includes a plurality of rings stacked in an axial direction one in abutment with another. Each ring has an inner face and an outer face. The piston ring assembly also includes a spring which substantially circumferentially surrounds the stacked rings and abuts the outer faces of the rings. The spring biases the stacked rings in a radially inward direction for sealing the inner faces of the rings against the piston body. The spring may be of a strip of material bent into a serpentine pattern when in an at rest condition to apply the biasing force against the piston body.

A piston ring includes a plurality of first ring pieces placed inside the ring groove in a stacking manner such that the first ring pieces adhere to each other in the axis direction. The first ring pieces include respective piston ring gap portions each having end surfaces separated from each other in the circumferential direction of the first ring pieces such that the end surfaces face each other via a ring gap having a predetermined dimension. The respective piston ring gap portions of the first ring pieces are displaced from each other in the circumferential direction. A closing member is provided to close the piston ring gap portions of the first ring pieces in the radial direction of the first ring pieces.

Provided is a piston ring for an internal combustion engine that enables size reduction of a chamfered edge without leading to the chipping, and sufficient size reduction of a flow passage of a blow-by gas in a piston ring gap, thus effectively restraining the blow-by gas from passing through the piston ring gap. A piston ring 1 with a piston ring gap 2 used for an internal combustion engine includes a chamfered edge 3 continuous to at least one of piston ring end faces at the piston ring gap 2 and an outer peripheral surface 1a of the piston ring 1. The chamfered edge 3 has a curved shape.

A piston seal assembly is disclosed comprising a seal and a seal energizer which supports the seal. The piston seal assembly comprises one component that is designed to position the seal energizer in a fixed axial position within the piston groove. In one embodiment, the seal energizer has the shape of a split ring with at least one of its lateral surfaces shaped to position the energizer in a fixed position within a piston groove. In other embodiments the piston seal assembly comprises a spacer that is positioned next to the seal energizer within the piston groove and is designed to position the seal energizer in a fixed axial position. The piston seal assembly can comprise a seal that has a portion which protrudes between the seal energizer and the piston groove wall such that it positions the seal energizer in a fixed axial position within the piston groove.