A method for manufacturing an engine poppet valve may comprise a forging operation, a diameter-decreasing operation, and a joining operation. At the forging operation, an intermediate member at which a valve head portion and an intermediate stem portion are made integral by way of a neck portion may be formed. At the diameter-decreasing operation, the intermediate stem portion may be inserted between/among a plurality of diameter-decreasing tools that have stem member compressing surfaces and stem member inlet surfaces formed so as to be progressively distant from the stem member compressing surfaces and toward the tip end and that are arranged at a plurality of circumferentially equipartite locations about a circumference of the intermediate stem portion, application at the intermediate stem portion from a base end portion of compressive forces which are inwardly directed in a radial direction from the compressing surfaces of the respective diameter-decreasing tools which have been made to come in contact with a part of the intermediate stem portion that has been made to rotate while being displaced in relative fashion in a direction along a central axis thereof causing the part of the intermediate stem portion to be decreased in diameter from the base end portion and causing a main body portion of a first stem portion to be formed at the intermediate member and also causing formation by the compressing surfaces of a stepped portion which is continuous with the main body portion, and formation, by an absence of decrease in diameter of a remaining portion at the intermediate stem portion, of a second stem portion which is broader in girth than the main body portion and which is continuous with the neck portion and which is also continuous with the main body portion by way of the stepped portion. At the joining operation, a stem end member having a same outside diameter as the main body portion may be joined to a base end portion of the main body portion.

A poppet including a single-piece, unitary body defining a plurality of discrete sealing surfaces and a mechanical attachment configured to engage the body with a piston of a valve assembly.

Welded check valves include a poppet assembly, a spring, and a disc that contacts the spring. The disc may be held at a position away from a weld when forming the welded check valve. Embodiments may include retention features configured to allow one or more of the poppet assembly and disc to pass the retention features in an assembly orientation, and to retain those elements when they are in an operational orientation. Methods include inserting the poppet assembly, contacting the poppet assembly with a spring, inserting a disc, retaining the disc away from a weld side, and welding the check valve together. The poppet assembly and/or disc may pass one or more retaining features when inserted, and be retained by the retaining features when the check valve is operated. The weld may be a thermal weld.

A matrix for shaping a valve preform has a circular through opening and a reduced conical section. The reduced conical section tapers from an outer diameter to a reduced cone inner diameter, the outer diameter being greater than or equal to the initial outer diameter of the valve preform, and the matrix inner diameter being smaller than the initial outer diameter.

A method for manufacturing an engine poppet valve comprising a valve head portion manufacturing operation in which hot forging is employed to form a stem/head intermediate product; a stepped stem portion manufacturing operation in which cold drawing is employed to cause a stepped stem portion comprising a first stem portion which has been made to be of decreased diameter, a step portion which has been formed by a stem member inlet surface, and a second stem portion in which there is absence of decrease in diameter and which is continuous by way of the step portion with the first stem portion to be formed from an intermediate stem portion; and a joining operation in which a stem end portion having a same outside diameter as the first stem portion is joined to a base end portion of the first stem portion.

A gas exchange valve for an internal combustion engine may include a valve stem and a wear resistance improving functional layer. The valve stem may extend in an axial direction and may transition into a valve plate in the axial direction. The functional layer may include nickel and tungsten. The functional layer may be arranged in a coating area on an outer circumference of the valve stem and may at least partially define a sliding surface.

A valve assembly may include a seat that is formed integrally (e.g., cast) into a dovetail shaped cavity. A portion of the seat is present above the surface of the disc according to a desired profile and to provide a bubble tight seal. Walls of the dovetail may include an angled surface (e.g., 45 degrees) for retention considerations. The dovetail may be cast, as opposed to machined, to reduce manufacturing costs. Additionally, the seat may be mechanically deformed before it can be removed.

Poppet valve for an internal combustion engine including a valve stem and a single circular valve head attached at one end of the valve stem. The valve head has a circular peripheral contour and an arcuate edge without any sharp elements to avoid turbulence and improve flow around the valve to therefore maximize flow velocity. This translates into increased cylinder breathing in the intake cycle and reducing back pressure in the exhaust cycle.

Poppet valve for an internal combustion engine including a valve stem and a single circular valve head attached at one end of the valve stem. The valve head has a circular peripheral contour and an arcuate edge without any sharp elements to avoid turbulence and improve flow around the valve to therefore maximize flow velocity. This translates into increased cylinder breathing in the intake cycle and reducing back pressure in the exhaust cycle.

An umbrella part metallic sodium insertion device for inserting rod-shaped metallic sodium into a hollow part of a hollow valve; a melting device for melting the metallic sodium in the hollow part by inserting a push rod from an opening into the hollow part of the hollow valve, in which the metallic sodium has been inserted by the device, and, while pushing the rod-shaped metallic sodium in the hollow part, heating the umbrella part to a temperature at which the metallic sodium is melted; a stem part cooling device for cooling a stem part of the hollow valve, in which the metallic sodium has been melted by the melting device, to a temperature lower than the temperature at which the metallic sodium is melted; and a stem part metallic sodium insertion device for inserting rod-shaped metallic sodium into the hollow part which has been cooled by the device.