Gas Shuttle Valve Provided With an Anti-Corrosive Layer

Abstract

A gas exchange valve of an internal combustion engine having a valve cone essentially made of a valve shaft, which passes into a valve plate while forming a hollow cone, and the valve cone or at least the valve shaft up into the area of the hollow cone being manufactured from a typical valve steel made of a nitride-forming based alloy, such that its parts which comprise a typical valve steel also have good corrosion protection. The valve cone is provided at least in partial areas with a corrosion protection layer in the form of a nitride layer, and the corrosion protection layer is generated by reacting the nitride-forming based alloy by plasma nitration or plasma nitro-carburization in a nitrogen atmosphere.

1 . A gas exchange valve of an internal combustion engine, comprising:
 a valve cone, said valve cone comprising:
 a valve shaft and a valve disk, the valve shaft is connected to and extends into the valve disk while forming a hollow cone, at least the valve shaft being manufactured from a valve steel comprised of a nitride-forming based alloy up into an area of the hollow cone; and 
 a corrosion protection layer provided on at least partial areas of the valve cone, said corrosion protection layer comprising at least one of a nitride and carbon nitride layer; 
   wherein the corrosion protection layer is generated by reacting the nitride-forming base alloy by one of plasma nitration and plasma nitro-carburization in a nitrogen atmosphere.   
   
   
       2 . The gas exchange valve according to  claim 1 , wherein the gas exchange valve is a one piece valve; and
 wherein the corrosion protection layer is provided on an entire area of the valve cone, extending up to an armored valve seat area of the valve disk and a front side of the valve shaft.   
   
   
       3 . The gas exchange valve according to  claim 1 , wherein the gas exchange valve is a two-piece valve; and
 wherein valve shaft is provided, at least on external faces that contact combustion gases within the engine, with the corrosion protection layer extending completely up to a boundary face between the valve shaft and the valve disk, at which the valve steel material is also delimited, while at least one of the valve disk and the area of the hollow cone remain uncovered by the corrosion protection layer.   
   
   
       4 . The gas exchange valve according to  claim 1 , wherein the corrosion protection layer has a diffusion layer thickness of 0.1 mm to 0.3 mm and a built up bonding layer on the diffusion layer of 3 μm to 15 μm and a surface hardness greater than 750 HV (Vickers). 
   
   
       5 . The gas exchange valve according to  claim 4 , wherein the diffusion layer thickness is the nitration hardness depth. 
   
   
       6 . The gas exchange valve according to  claim 2 , wherein the corrosion protection layer has a diffusion layer thickness of 0.1 mm to 0.3 mm and a built up bonding layer on the diffusion layer of 3 μm to 15 μm and a surface hardness greater than 750 HV (Vickers). 
   
   
       7 . The gas exchange valve according to  claim 3 , wherein the corrosion protection layer has a diffusion layer thickness of 0.1 mm to 0.3 mm and a built up bonding layer on the diffusion layer of 3 μm to 15 μm and a surface hardness greater than 750 HV (Vickers). 
   
   
       8 . The gas exchange valve according to  claim 6 , wherein the diffusion layer thickness is the nitration hardness depth. 
   
   
       9 . The gas exchange valve according to  claim 7 , wherein the diffusion layer thickness is the nitration hardness depth.