A method for producing at least one hollow valve for gas exchange may include introducing a bore into a valve shaft and into a valve head to form the at least one hollow valve, measuring a depth of the bore, washing the at least one hollow valve at least once, providing the at least one hollow valve in a retaining device, orienting the retaining device together with the at least one hollow valve with respect to an associated electrode, moving the associated electrode in relation to the at least one hollow valve, inserting the associated electrode into the bore of the at least one hollow valve, enlarging the bore in a region of the valve head by electromechanical machining processes, removing the associated electrode from the at least one hollow valve, rinsing and/or preserving the at least one hollow valve, and measuring a wall thickness of a valve bottom.

A method of charging a hollow valve with metallic sodium includes providing a workpiece, as a semi-finished product for a hollow poppet valve, in which a cavity has an upward opening at a free end of a valve stem at a working position; inserting a nozzle into the opening to feed an initial inert gas into the cavity by jetting the inert gas from the nozzle; moving up the nozzle to put a holder between the workpiece and the nozzle, the holder holding a rod-like metallic sodium; and inserting the nozzle into a first end of the holder while an additional inert gas is jetted into the cavity from the nozzle to push down the rod-like metallic sodium along with the inert gas from a second end of the holder into the cavity of the workpiece.

A method for producing a valve body of a hollow valve includes providing a workpiece blank or semi-finished product, spin extruding the workpiece to produce a preform having a cup with a hollow shape formed by the cup wall. A hollow valve produced by this method is also provided.

A method for producing a valve body of a hollow valve with optimised interior stem geometry includes a preform with a valve plate and a tubular wall surrounding a cavity. Flow forming the tubular wall over a flow-forming mandrel, which is inserted into the cavity to enlarge a length of the tubular wall. An interior area of the tubular wall is embossed with a structure either due to the fact that the flow-forming mandrel is a structuring mandrel having a surface structure, or alternatively, because the method includes a further step of reducing an outer diameter of the tubular wall by swaging or drawing and ironing over a structuring mandrel. Furthermore, a hollow valve is produced by this method.

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 poppet valve includes: a valve body comprising a valve stem body, a valve head body with a valve combustion face, and a valve fillet body interconnecting the valve stem body and the valve head body. The valve fillet body surface has an increased thermal resistance compared to the valve combustion face.

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.

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.

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.