Abstract: A piston assembly for an internal combustion engine includes a cylinder bore and a piston having exactly two ring grooves, a scraper ring positioned in the upper ring groove, and an oil control ring positioned in the lower ring groove. A constant twist occurs in the scraper ring about a rotational center of the cross-section, the constant twist occurring at each cross-sectional location of the scraper ring about the circumference of the ring and between adjacent free ends of the ring. The oil control ring can be of a multi-segmented U-flex design, with a coil spring mounted in a channel thereof. The combination of the two rings leads to improved sealing and oil control so that the piston can be manufactured with only two rings, thus reducing overall weight and cost.

Abstract: A piston assembly for an internal combustion engine includes a cylinder bore and a piston having exactly two ring grooves, a scraper ring positioned in the upper ring groove, and an oil control ring positioned in the lower ring groove. A constant twist occurs in the scraper ring about a rotational center of the cross-section, the constant twist occurring at each cross-sectional location of the scraper ring about the circumference of the ring and between adjacent free ends of the ring. The oil control ring can be of a multi-segmented U-flex design, with a coil spring mounted in a channel thereof. The combination of the two rings leads to improved sealing and oil control so that the piston can be manufactured with only two rings, thus reducing overall weight and cost.

Abstract: A piston having a piston crown with a combustion chamber, and a circumferential ring belt extending from the piston crown and having a plurality of ring grooves separated by piston lands. At least one of the piston lands, ring grooves or top surface of the crown is provided with a coating comprising hexagonal boron nitride. The coating can be made solely of hexagonal boron nitride, or can additionally include a resin. The coating can be a single layer coating or a multiple layer coating.

Abstract: A piston ring and a method of forming a piston ring. A masking agent is applied to a selective area on an exterior surface of a piston ring. The masking agent inhibits the subsequent application of additional coatings to the selective area on the exterior surface of the piston ring. In one form, the masking agent may inhibit the subsequent application of a nitride layer to the selective area on the exterior surface of the piston ring. A recess may be formed in an outer peripheral side of the piston ring, and a thermal spray coating may be formed within the recess in the outer peripheral side of the piston ring.

Abstract: A piston having a piston crown with a combustion chamber, and a circumferential ring belt extending from the piston crown and having a plurality of ring grooves separated by piston lands. At least one of the piston lands, ring grooves or top surface of the crown is provided with a coating comprising hexagonal boron nitride. The coating can be made solely of hexagonal boron nitride, or can additionally include a resin. The coating can be a single layer coating or a multiple layer coating.

Abstract: Exemplary piston rings are disclosed, comprising a base portion formed of a metallic material, and an outer contact surface extending between opposing side faces of the piston ring. The piston ring may include a coating layer applied to the outer contact surface, with the coating layer including an inner layer and an outer layer. Exemplary methods of making a piston ring are also disclosed, comprising providing a base portion formed of a metallic material, applying an inner layer to an outer surface of the base portion, and applying an outer layer on top of the inner layer.

Abstract: Various methods including applying a coating material with an additive to an article are disclosed. The coating material may be in a powder form before a thermal spraying used to apply the coating material. The coating material may comprise a chromium nitride, a chromium carbide, a chromium silicide, or a tungsten carbide. Additional materials may be added, e.g., a molybdenum alloy such as molybdenum-chromium. In one aspect, thermal spraying includes melting the coating material, propelling the molten coating material toward the article to be coated, and coating the article with the molten coating material. In another aspect, the coated article is one or more piston rings.

Abstract: Internal combustion engines use piston rings to provide a necessary seal between the piston and cylinder wall. The piston rings are designed to seal in the gases produced above the piston during the combustion process. The more intimate the contact between the piston ring and cylinder wall, the more effective this seal will be. The more effective the seal, the more power produced by the engine. Ideally, the entire outer piston ring surface should tightly and completely contact the cylinder wall. The contact of the ring against the cylinder wall produces a constant frictional force on the ring and cylinder wall during normal engine operation. The frictional force causes the outer surface edge of the piston ring to wear. Piston rings used in an internal combustion engine comprise a base metal formed into a ring. The base metal has a low resistance to frictional wear. To reduce the wear on the ring, plating and coating operations are performed on the ring.

Abstract: Various methods including applying a coating material with an additive to an article are disclosed. The coating material may be in a powder form before a thermal spraying used to apply the coating material. The coating material may comprise a chromium nitride, a chromium carbide, a chromium silicide, or a tungsten carbide. Additional materials may be added, e.g., a molybdenum alloy such as molybdenum-chromium. In one aspect, thermal spraying includes melting the coating material, propelling the molten coating material toward the article to be coated, and coating the article with the molten coating material. In another aspect, the coated article is one or more piston rings.

Abstract: Exemplary piston rings are disclosed, comprising a base portion formed of a metallic material, and an outer contact surface extending between opposing side faces of the piston ring. The piston ring may include a coating layer applied to the outer contact surface, with the coating layer including an inner layer and an outer layer. Exemplary methods of making a piston ring are also disclosed, comprising providing a base portion formed of a metallic material, applying an inner layer to an outer surface of the base portion, and applying an outer layer on top of the inner layer.

Abstract: A secondary seal is provided for an internal combustion engine having a piston, cylinder bore, ring seal, secondary seal, and leak path. Forces are applied from the combustion side of the piston through a cylinder gap and a leak path to the secondary seal. The secondary seal, seated on the piston and ring seal, transmits the forces generally axially to the piston and ring seal, thereby controllably limiting the radial force between the ring seal and cylinder bore.