Abstract: 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.

Abstract: A power cylinder assembly for an internal combustion engine is provided. The power cylinder assembly includes a cylinder wall having a channel formed therein and a piston body with a skirt. A piston ring is seated within the channel of the cylinder wall and is sealed against the skirt of the piston body. Specifically, the piston ring has a ring body with an inner face that presents two radially inwardly extending ridges spaced axially from one another by a valley region, and the outer face presents a groove which receives a spring to bias the ridges into sliding engagement with the outer surface of the skirt of the piston body. The ring body also has at least one oil drainage port which extends radially between the valley region of the inner surface and the groove of the outer face for conveying oil from between the ridges into the groove.

Abstract: A piston ring for sealing a cylinder wall to a piston body is provided. The piston ring includes a ring body of an elastically deformable material which extends substantially circumferentially around an axis and has an inner face that faces the axis. The inner face includes a plurality of axially spaced and radially inwardly extending contact features. The ring body configured to bias the contact features into engagement with the piston body to establish a seal therebetween. At least one of the contact features extends substantially continuously around a circumference for establishing a substantially continuous seal around the piston body, and at least one of the contact features is non-continuous and has at least one recessed area for allowing the passage of oil and gas therethrough.

Abstract: A piston ring for sealing a cylinder wall to a piston body is provided. The piston ring includes a ring body that extends about an axis and has inner and outer faces. The inner face presents a pair of ridges that extend in a radially inward direction, and the outer face presents a groove. A spring of an elastomeric material substantially circumferentially surrounds the ring body and is seated in the groove on the inner face. The spring biases the ring body in the radially inward direction to seal the ridges against the piston body. The ring body also has at least one oil drainage port which extends at an angle relative to the radially inward direction from the inner face to a location on the outer face on one axial side of the spring for conveying oil out of a space between the ridges.