A sliding mechanism 1 includes a first sliding member 10 and a partner second sliding member 20 configured to slide relative to the first sliding member 10. The first sliding member 10 includes a matrix phase 11 and a hard phase 13 that is harder than the matrix phase 11, in which the hard phase 13 is embedded in the matrix phase 11 in a dispersed state. The second sliding member 20 includes a base 21 and a surface-treatment layer 23 that is formed on the sliding surface 20 of the base 21 and is harder than the matrix phase 11.

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.

A valve body for a gas exchange valve of a cylinder of an internal combustion engine can be brought to lie against a valve seat of the gas exchange valve for closing the gas exchange valve and can be removed from the valve seat to open the gas exchange valve. The valve body is formed in multiple parts and has a first valve disc part interacting with the valve seat and a second valve disc part that is connected to the first valve disc part in a fixed manner and faces a combustion chamber of the cylinder. Between the first valve disc part and the second valve disc part a hollow space serving at least for the cooling of the second valve disc part is formed.

A method for shaping a hollow valve preform of a pull rod (20) includes a structuring bulb (22) which is inserted into the cavity (56) of a shaft portion (44) of a valve preform. The structuring bulb (22) has an outer diameter, and has an outer structuring, whereafter the hollow shaft portion (44) is shaped, wherein at least a portion of an inner diameter of the cavity (56) is reduced below an outer diameter of the structuring bulb (22). The structuring bulb (22) is then pulled out through the shaped shaft portion (44), wherein the outer structuring is at least partially pressed into the surface of the cavity (56).

A method for shaping a hollow valve preform of a pull rod (20) includes a structuring bulb (22) which is inserted into the cavity (56) of a shaft portion (44) of a valve preform. The structuring bulb (22) has an outer diameter, and has an outer structuring, whereafter the hollow shaft portion (44) is shaped, wherein at least a portion of an inner diameter of the cavity (56) is reduced below an outer diameter of the structuring bulb (22). The structuring bulb (22) is then pulled out through the shaped shaft portion (44), wherein the outer structuring is at least partially pressed into the surface of the cavity (56).

Aspiration and multi-section slide valves (24) for internal combustion engines (11). The slide valves (24) include a central, reduced diameter neck (103) connecting separate cylindrical valve sections (104, 105), which have multiple spaced-apart ring groove arrays seating multiple rings. Slide valves (24) utilize spaced apart, continuously pressurized, annular oil confinement zones (101) that are defined between the slide valve exterior and its sleeve (27) between groups of piston ring arrays. The oil zones are axially spaced along the length of the slide valve and continuously pressured by oil flow passageways (106). During slide valve movement these pressurized oil zones tend to stabilize the slide valve (24), preventing metal-to-metal contact such as that associated with rocking, tipping, chafing or scrubbing. When appropriately displaced, the slide valve neck (103) facilitates transverse fluid flow through the slide valve and its confining sleeve between cylinder gas pathways (139, 141).

Aspiration and multi-section slide valves (24) for internal combustion engines (11). The slide valves (24) include a central, reduced diameter neck (103) connecting separate cylindrical valve sections (104, 105), which have multiple spaced-apart ring groove arrays seating multiple rings. Slide valves (24) utilize spaced apart, continuously pressurized, annular oil confinement zones (101) that are defined between the slide valve exterior and its sleeve (27) between groups of piston ring arrays. The oil zones are axially spaced along the length of the slide valve and continuously pressured by oil flow passageways (106). During slide valve movement these pressurized oil zones tend to stabilize the slide valve (24), preventing metal-to-metal contact such as that associated with rocking, tipping, chafing or scrubbing. When appropriately displaced, the slide valve neck (103) facilitates transverse fluid flow through the slide valve and its confining sleeve between cylinder gas pathways (139, 141).

A method for the production for a semi-finished valve product (4), includes casting, forging, deep-drawing, pressing and/or drop-welding of one or several metal material into a semi-finished valve product (4) that corresponds to a circle segment of a valve cut open in the axial direction. A valve is produced by welding together at least two semi-finished valve products (4) into an internally cooled valve, with the weld running in the axial direction of the valve.

A method for the production for a semi-finished valve product (4), includes casting, forging, deep-drawing, pressing and/or drop-welding of one or several metal material into a semi-finished valve product (4) that corresponds to a circle segment of a valve cut open in the axial direction. A valve is produced by welding together at least two semi-finished valve products (4) into an internally cooled valve, with the weld running in the axial direction of the valve.