Unique apparatuses and methods for scraping deposits from a piston as the piston moves in an upstroke direction and a downstroke direction. An engine assembly includes a cylinder having a cylinder bore, a piston having a crown end, wherein the piston is disposed in the cylinder bore and configured to move in an upstroke direction and a downstroke direction relative to the cylinder bore. The piston includes a first land positioned adjacent the crown end. An antipolishing ring is disposed within the cylinder bore. The antipolishing ring has an outer annular surface and an inner annular surface, the inner annular surface has one or more protrusions configured to scrape the first land when the piston moves in the upstroke direction and the downstroke direction. The protrusions are also configured to scrape the first land when the piston has secondary or lateral motion.

Provided is an engine, including: a cylinder including a cylinder liner; a piston provided inside the cylinder liner; a piston ring provided on the piston; a contact detector configured to detect a contact between a step formed in an inner peripheral surface of the cylinder liner and the piston ring; and a compression ratio controller configured to control a top dead center position of the piston so that the piston ring at the top dead center position is located on a combustion chamber side with respect to the step when the contact is detected.

A cylinder liner for an opposed-piston engine, and corresponding methods of extending engine durability and thermal management therewith, has opposite ends and a bore with a longitudinal axis for supporting reciprocating movement of a pair of opposed pistons. An intermediate portion of the liner extends between the opposite ends and includes an annular liner portion within which the pistons reach respective TC locations. A liner ring is seated in a portion of the bore in the annular liner portion, between the TC locations, for scraping carbon from top lands of the pistons and/or increasing the thermal resistance of the annular liner portion.

Cylinder liner for an internal combustion engine, comprising: a cylindrical portion having an outer diameter and an inner diameter, the inner diameter at least partly realizing a cylinder wall, when the cylinder liner is mounted in the internal combustion engine, a circumferential recess at the inner diameter of the cylindrical portion having a larger diameter than the inner diameter of the cylinder wall, wherein the circumferential recess is located at one end of the cylindrical portion, and a removable scraper ring, wherein the recess comprises at least one groove, wherein a size of the scraper ring is adapted to fit into the recess and to cover the at least one groove.

An anti-polish ring for an internal combustion engine is provided. The anti-polish ring includes an axially extending ring portion that is configured to scrape a top portion of a piston in a cylinder liner. The anti-polish ring is configured to accommodate passage of an intake or exhaust valve thereby. The anti-polish ring may include an alignment feature so that the anti-polish ring is inserted in a predetermined orientation in the cylinder. The anti-polish ring may include a heat shield and/or a seating member.

A piston includes a swirl pocket that extends radially from the radially outer lip portion to a lower axial extremity spaced away from the radially outer lip portion a first axial distance. A convex arcuate surface extends downwardly and inwardly from the radially outer lip portion, a concave arcuate surface extends to the lower axial extremity from the convex arcuate surface, and a conical portion extends upwardly and inwardly from the concave arcuate surface to an apex that is spaced a second axial distance from the radially outer lip portion that is less than the first axial distance.

A device and method for preventing and removing piston deposit build-up on a piston cylinder assembly of an engine, including a diesel engine, is disclosed. A cylinder having an inner sleeve for receiving a piston, has a piston scraping ring positioned on the cylinder sleeve. The piston scraping ring includes an inner surface, and has a curved or hook shaped feature on its inner surface. The curved or hook shaped feature, named the power groove for the purposes of this application, allows for reduced wear between the piston rings and the cylinder sleeve by reducing the pressure on the piston rings by expanding and reversing the flow of combustion gases. Additionally, this reversal of the combustion gases results in a decrease in blow-by gases passing between the piston rings and cylinder sleeve thereby improving sealing between the piston and the cylinder.

An arrangement may include one of a cylinder liner or a cylinder bore formed in a crankcase of an internal combustion engine, a piston having a peripheral top land and being accommodated in the cylinder liner or cylinder bore, and an annular insert accommodated in the cylinder liner or cylinder bore and extending axially parallel to the piston top land. The cylinder liner or cylinder bore may have a radially inwardly-directed shoulder at an upper free end of the cylinder liner or cylinder bore. The annular insert may have along an upper peripheral free edge of the annular insert, distributed around a circumference of the annular insert, at least two beads or embossments located opposite one another and resting on the radially inwardly-directed shoulder.

An internal combustion engine includes: a cylinder in which a piston reciprocates; a stepped portion that is formed on an upper end portion of an inner peripheral surface of the cylinder; and a ring member having a cylindrical shape provided to the stepped portion. The thickness of the ring member decreases toward the bottom dear center of the piston, and an outer peripheral surface of the ring member is an inclined surface, where a lower end of the outer peripheral surface is positioned closer to the center in the radial direction of the ring member than an upper end of the outer peripheral surface.

An internal combustion engine includes: a cylinder in which a piston reciprocates; a cylinder head positioned above the cylinder; a gasket disposed between the cylinder and the cylinder head; a stepped portion that is formed at an upper end portion of an inner peripheral surface of the cylinder and positioned below the gasket; a ring member having a cylindrical shape provided to the stepped portion; and a protrusion portion that is formed in a manner to protrude from the ring member and bites into a lower surface of the gasket.