Provided is a method for filling a stem-side hollow area of an engine valve with metallic sodium. The method includes injecting melted metallic sodium into a cylinder having a larger diameter than an inner diameter of the hollow area of the engine valve, forming a solidified metallic sodium rod having a substantially uniform structure in the cylinder, inserting the metallic sodium into the hollow area of the engine valve through a nozzle having a small diameter, and sealing the engine valve.

Disclosed is a method for the production of a valve body of a hollow chamber valve, said method comprising: providing a bowl-shaped semi-finished product having an annular wall, which surrounds a hollow chamber, and a bottom portion, followed by a lengthening of the wall and a final reducing of an outer diameter of the annular wall in order to obtain a predetermined valve shaft outside diameter of a valve that is to be produced. Further disclosed is a hollow chamber valve produced by means of said method.

Disclosed is a method for the production of a valve body of a hollow chamber valve, said method comprising: providing a bowl-shaped semi-finished product having an annular wall, which surrounds a hollow chamber, and a bottom portion, followed by a lengthening of the wall and a final reducing of an outer diameter of the annular wall in order to obtain a predetermined valve shaft outside diameter of a valve that is to be produced. Further disclosed is a hollow chamber valve produced by means of said method.

The invention relates to a process for manufacturing an internally cooled valve, said process involving providing an externally at least partly cylindrical semifinished product (2), creating or increasing the depth of an at least partly cylindrical cavity in the semifinished product (2) in a hot-working procedure using a male die such that a valve blank is formed; during the hot-working procedure, a recess on an end face of the male die forms a structure on the bottom of the cavity.

The invention relates to a process for manufacturing an internally cooled valve, said process involving providing an externally at least partly cylindrical semifinished product (2), creating or increasing the depth of an at least partly cylindrical cavity in the semifinished product (2) in a hot-working procedure using a male die such that a valve blank is formed; during the hot-working procedure, a recess on an end face of the male die forms a structure on the bottom of the cavity.

The present invention provides a hollow engine valve achieving high durability while suppressing an increase in manufacturing cost, and a manufacturing method therefor. A manufacturing method for a hollow engine valve comprises: a step of forming, by forging, a solid round bar as a material of a valve main body into a valve main body intermediate member provided with a semifinished product valve head portion corresponding to a valve head portion and a solid stem portion corresponding to a valve stem portion; a step of performing cutting process with respect to the valve main body intermediate member across the solid stem portion and the semifinished product valve head portion for forming a semifinished product hollow hole with a bottom corresponding to a hollow hole, thereby forming the valve main body intermediate member into a valve main body semifinished product provided with the semifinished product valve head portion and a semifinished product valve stem portion; and a step of performing necking process with respect to the valve main body semifinished product for squeezing the semifinished product valve stem portion step by step, thereby reducing the diameter of the semifinished product valve stem portion and increasing the length of the stem of the semifinished product valve stem portion, to form the valve main body semifinished product into the valve main body.

The present invention provides a hollow engine valve achieving high durability while suppressing an increase in manufacturing cost, and a manufacturing method therefor. A manufacturing method for a hollow engine valve comprises: a step of forming, by forging, a solid round bar as a material of a valve main body into a valve main body intermediate member provided with a semifinished product valve head portion corresponding to a valve head portion and a solid stem portion corresponding to a valve stem portion; a step of performing cutting process with respect to the valve main body intermediate member across the solid stem portion and the semifinished product valve head portion for forming a semifinished product hollow hole with a bottom corresponding to a hollow hole, thereby forming the valve main body intermediate member into a valve main body semifinished product provided with the semifinished product valve head portion and a semifinished product valve stem portion; and a step of performing necking process with respect to the valve main body semifinished product for squeezing the semifinished product valve stem portion step by step, thereby reducing the diameter of the semifinished product valve stem portion and increasing the length of the stem of the semifinished product valve stem portion, to form the valve main body semifinished product into the valve main body.

There is provided an engagement groove (31) which is formed in a first shoe (S1) of first to fourth shoes (S1), (S2), (S3), (S4) at a circumference position at which the engagement groove (31) is not overlapped an abutment surface (30) with a first vane (V1), which includes a pair of side surfaces (31a) and (31a) that are substantially parallel to the abutment surface (30), and with which a positioning pin (19) protruding from a sprocket (13) is engaged, so as to match phases of a housing main body (11) and the sprocket (13) in a rotation direction.

The present invention provides a hollow engine valve achieving high durability while suppressing an increase in manufacturing cost, and a manufacturing method therefor. A manufacturing method for a hollow engine valve comprises: a step of forming, by forging, a solid round bar as a material of a valve main body into a valve main body intermediate member provided with a semifinished product valve head portion corresponding to a valve head portion and a solid stem portion corresponding to a valve stem portion; a step of performing cutting process with respect to the valve main body intermediate member across the solid stem portion and the semifinished product valve head portion for forming a semifinished product hollow hole with a bottom corresponding to a hollow hole, thereby forming the valve main body intermediate member into a valve main body semifinished product provided with the semifinished product valve head portion and a semifinished product valve stem portion; and a step of performing necking process with respect to the valve main body semifinished product for squeezing the semifinished product valve stem portion step by step, thereby reducing the diameter of the semifinished product valve stem portion and increasing the length of the stem of the semifinished product valve stem portion, to form the valve main body semifinished product into the valve main body.

The present invention provides a hollow engine valve achieving high durability while suppressing an increase in manufacturing cost, and a manufacturing method therefor. A manufacturing method for a hollow engine valve comprises: a step of forming, by forging, a solid round bar as a material of a valve main body into a valve main body intermediate member provided with a semifinished product valve head portion corresponding to a valve head portion and a solid stem portion corresponding to a valve stem portion; a step of performing cutting process with respect to the valve main body intermediate member across the solid stem portion and the semifinished product valve head portion for forming a semifinished product hollow hole with a bottom corresponding to a hollow hole, thereby forming the valve main body intermediate member into a valve main body semifinished product provided with the semifinished product valve head portion and a semifinished product valve stem portion; and a step of performing necking process with respect to the valve main body semifinished product for squeezing the semifinished product valve stem portion step by step, thereby reducing the diameter of the semifinished product valve stem portion and increasing the length of the stem of the semifinished product valve stem portion, to form the valve main body semifinished product into the valve main body.