A steel piston designed to improve thermal efficiency, fuel consumption, and performance of an engine is provided. The piston includes a steel body portion and a thermal barrier layer applied to an upper combustion surface and/or a ring belt to reduce the amount of heat transferred from a combustion chamber to the body portion. The thermal barrier layer has a thermal conductivity which is lower than a thermal conductivity of the steel body portion. The thermal barrier layer typically includes a ceramic material, for example ceria, ceria stabilized zirconia, and/or a mixture of ceria stabilized zirconia and yttria stabilized zirconia in an amount of 90 to 100 wt. %, based on the total weight of the ceramic material. The thermal barrier layer can also have a gradient structure which gradually transitions from 100 wt. % of a metal bond material to 100 wt. % of the ceramic material.

A piston capable of reducing undesirable knock, reducing hydrocarbon emissions, and providing more complete combustion, is provided. The piston includes a multilayer coating having a thickness of 500 microns or less disposed on an upper combustion surface. The coating includes a bond layer including nickel disposed on the upper combustion surface. A thermal barrier layer including a ceramic composition is disposed on the bond layer. A sealant layer formed of metal is disposed on the thermal barrier layer. A catalytic layer including at least one of platinum, ruthenium, rhodium, palladium, osmium, and iridium is disposed on the sealant layer. The catalytic layer can be disposed on select regions or the entire upper combustion surface to promote combustion through a catalyzed reaction.

A steel piston for an internal combustion including a cooling gallery containing a solid coolant, such as an aluminum-based material, is provided. The solid coolant has a thermal conductivity which is greater than the thermal conductivity of the steel material and fills at least 15 volume percent (vol. %) of the cooling gallery. The solid coolant provides for exceptional cooling along a crown of the piston, reduces corrosion and erosion along the crown, and avoids the problem of oil coking.

A steel material has a chemical composition which consists of, in mass %, C: 0.15 to 0.30%, Si: 0.02 to 1.00%, Mn: 0.20 to 0.80%, P: 0.020% or less, S: 0.028% or less, Cr: 0.80 to 1.50%, Mo: 0.08 to 0.40%, V: 0.10 to 0.40%, Al: 0.005 to 0.060%, N: 0.0150% or less, O: 0.0030% or less, and the balance: Fe and impurities, and satisfies Formulae (1) and (2), in which, at a cross section parallel to the axial direction of the steel material for a steel piston, the number of Mn sulfides is 100.0 per mm.sup.2 or less, the number of coarse Mn sulfides having an equivalent circular diameter of 3.0 m or more is in a range of 1.0 to 10.0 per mm.sup.2, and the number of oxides is 15.0 per mm.sup.2 or less.
0.42Mo+3V1.50(1)
V/Mo0.50(2)

A galleryless piston for an internal combustion engine and method of construction thereof are provided. The piston has a monolithic piston body extending along a central longitudinal axis. The piston body has an upper wall forming an upper combustion surface with first and second portions, with the first portion extending annularly along an outer periphery of the upper wall and the second portion forming a combustion bowl. The upper wall has an undercrown surface on an underside of the combustion bowl directly opposite the second portion of the upper combustion surface. The undercrown surface has an openly exposed 2-dimensional surface area, as viewed looking along the central longitudinal axis, between about 35-60 percent of an area defined by a maximum outer diameter of the piston body, thereby providing an expansive area against which oil being splashed or sprayed can freely contact to cool the piston.

A three section steel piston for two-stroke engines is provided. The piston is provided with an upper section, a middle section and a lower section. Piston ring grooves are formed into the upper and lower sections, and pin bosses with openings and skirts are formed into the middle section. The middle section has relatively thinner walls as compared to the portions of the upper and lower sections at the piston ring grooves to reduce the mass of the piston. A closed cooling gallery may be formed adjacent an upper combustion surface of the piston with the cooling gallery being defined at least partially by the upper section.

A piston for an internal combustion engine is provided. The piston includes a piston body which is made of steel. The piston body has a crown portion with an upper combustion surface, a pair of skirts which depend from the crown surface, a pair of pin bosses for receiving a wrist pin and a plurality of pin boss bridges which extend from the pin bosses to the skirts. Each of the pin boss bridges extends axially to a lower end which is opposite of the crown portion and has a rib with an increased thickness at its lower end. At least one of the pin boss bridges has a generally flat counter-bore surface for providing a reference location for machining of the piston body.

A steel piston achieving increased thermal brake efficiency in an internal combustion engine is provided. The piston includes a crown presenting a combustion surface, an outer side wall depending from the combustion surface, an outer cooling gallery, and an undercrown cooling gallery. The outer cooling gallery extends circumferentially along the outer side wall beneath the combustion surface. According to one embodiment, the outer cooling gallery is sealed and filled with air, argon, helium, xenon, or carbon dioxide as a cooling media. In this embodiment, the undercrown cooling gallery is filled with air as a cooling media and includes an open inlet hole having a diameter being from 2% to 4% of an outer diameter of the piston. Alternatively, the undercrown cooling gallery is filled with air, argon, helium, xenon, or carbon dioxide as a cooling media, and the inlet hole is sealed.

The invention relates to a method for producing a piston (1) for an internal combustion engine, characterized by the following method steps: producing an upper piston part (2) and a lower piston part (3) having one or more recesses (4, 4) for forming a closed cavity (5); introducing a heat transfer medium (6), in particular one or more alkali metals, that is solid or paste-like at ambient temperature and liquid at the intended operating temperature of the piston, into the recesses (4, 4) of the lower piston part (3) and/or of the upper piston part (2), wherein the heat transfer medium (6) is provided in order, during the operative state of the piston (1), to effect heat transport within the piston (1) by convection; closing the recesses to form the closed cavity (5) which encloses the heat transfer medium (6); and connecting the upper piston part (2) to the lower piston part (3). This enables the piston (1) to be produced in a simplified manner.