A uniflow engine includes a cylinder having a cylinder wall, a volume exterior to the cylinder, at least one channel extending between the cylinder wall and the volume, and a valve outside of the cylinder configured to open and close flow communication between the cylinder and the volume through the channel.

A port opening edge shape for a port in a cylinder of an opposed-piston combustion engine is optimized for flow area, as well as for minimization of piston ring clipping. The port opening edge shape includes a top edge, a bottom edge, a first and second side edge connecting the top and bottom edge, and an apex in the top edge. The apex has the minimum radius of curvature of the port opening edge shape. A spline that defines the port opening edge shape can be calculated based upon a maximum height, a full width, an amount or degree of skew, and a minimum radius of curvature. A model can measure values for engine performance and determine which spline defines a port opening edge shape yields a desired engine performance.

An opposed-piston engine assembly is disclosed including a first cylinder liner containing a pair of first pistons that move toward one another in one mode of operation and away from one another in another mode of operation. The pistons are coupled to first and second crankshafts. Multiple block segments arranged in a side-by-side abutting relationship form the engine block including a first outboard segment, a first inboard segment, a second inboard segment, and a second outboard segment. Tensile members extend through the block segments tying them together as one structural unit. The first and second inboard segments abut one another at a seam and include bores that cooperate to receive the first cylinder liner. The first cylinder liner includes a liner support collar that is received in counter-bores defined by the first and second inboard segments at the seam between the first and second inboard segments.

Technology is provided for a cylinder with a carbon scraper for use in an opposed piston engine. The cylinder includes a cylinder body having first and second piston bores extending along a central axis for reciprocation of corresponding first and second pistons therein. A chamber bore is located between the first and second piston bores and first and second annular grooves are located on opposite ends of the chamber bore. The chamber bore extends between and is inclusive of a top-dead-center position of a top land of each of the first and second pistons. The first and second piston bores have a piston diameter and the chamber bore has a chamber diameter smaller than the piston diameter. For example, the chamber diameter can be between about 0.004 and about 0.020 inches smaller than the piston diameter.

An example of a cylinder liner according to the present disclosure includes a first portion having a first end and a second end and a second portion having a first end and a second end. The second portion is separate from the first portion and the second end of the first portion overlays the first end of the second portion. The first portion and the second portion are configured to receive a piston slideably disposed within the first portion and the second portion.

In ported engine constructions, cooling of piston crowns and cylinder liners results in reduction or elimination of bore/liner distortions, thus ensuring circularity of the bore/piston interface throughout engine operation. Consequently, the need for heavily-tensioned piston rings is eliminated. Such engine constructions incorporate annular low-tension compression seals on the pistons, which substantially reduce port bridge wear during all phases of engine operation while also limiting blow-by during combustion.

A reciprocating cylinder seal assembly has an elastomeric seal with a radially inwardly directed oil sealing lip and a radially inwardly directed gas sealing lip, wherein both lips are in elastomeric-to-metal sealing contact with a reciprocating engine liner. The assembly further has a U-shaped seal retainer that is attached to the elastomeric seal, where the U-shaped seal retainer is placed in direct intimate contact with a cylindrical engine housing. The U-shaped seal retainer and a reciprocating engine housing may be separated by and be in contact with a major portion of a J-shaped gas shield with a hook portion that is located between the oil sealing lip and a manifold port, where the hook portion of the J-shaped gas shield has a metal backer ring embedded in it.

A reciprocating cylinder seal assembly has an elastomeric seal with a radially inwardly directed oil sealing lip and a radially inwardly directed gas sealing lip, wherein both lips are in elastomeric-to-metal sealing contact with a reciprocating engine liner. The assembly further has a U-shaped seal retainer that is attached to the elastomeric seal, where the U-shaped seal retainer is placed in direct intimate contact with a cylindrical engine housing. The U-shaped seal retainer and a reciprocating engine housing may be separated by and be in contact with a major portion of a J-shaped gas shield with a hook portion that is located between the oil sealing lip and a manifold port, where the hook portion of the J-shaped gas shield has a metal backer ring embedded in it.

A two-stroke, opposed-piston engine with one or more ported cylinders and uniflow scavenging includes an exhaust gas recirculation (EGR) construction that provides a portion of the exhaust gasses produced by the engine for mixture with charge air to control the production of NOx during combustion.

A method for coating a surface with a coating jet containing coating particles includes forming the coating jet from at least two partial jets. The method also includes forming one of the exit channels as a spray channel for a first gas stream containing the coating particles. The method also includes forming the other of the exit channels as a control channel. In case of a deviation of the ascertained spray angle () from the predetermined target spray angle, the method also includes increasing the volume flow of a first partial jet of the at least two partial jets, and decreasing the volume flow of a second partial jet of the at least two partial jets.