Valve for Controlling Gas Exchange, Especially in Internal Combustion Engines

Abstract

A valve for controlling gas exchange, especially in internal combustion engines, comprises, at a valve stem, a stem end and at the other end thereof a valve cone. The valve cone and/or the valve stem are configured as hollow metal elements in such a manner that the hollow elements are entirely or partially filled with a metal foam. The interfaces between the metal and the metal foam are interlinked on the molecular level.

1 . A method for manufacturing a valve for control of gas exchange, suitable for internal combustion engines, the valve comprising a valve cone at one end of a valve stem, the valve stem and/or valve cone being formed as hollow metal parts having a cavity filled at least partly with metal foam to form a metal-foam body, wherein the metal-foam body formed in the valve cavity is bonded metallically at the molecular level at the interfaces with the hollow metal parts forming the valve without the use of an interfacial layer of bonding material between the metal-foam body and the valve cavity, the method comprising:
 introducing starting material for the metal foam through one open end of the valve stem in such a way that the metal foam completely fills the valve cavity and molecularly bonds with the valve, without the use of an interfacial layer of bonding material between the metal foam and the valve cavity, under the effect of heat, and its quantity is adjusted to swell beyond the filling end;   removing the excess quantity of metal foam; and   sealing the filling opening.   
   
   
       2 . The method according to  claim 1 , further comprising processing the metal foam in such a way that the metal foam has closed or open pores. 
   
   
       3 . The method according to  claim 2 , wherein the metal foam has open pores, further comprising filling the open pores with a coolant. 
   
   
       4 . The method according to  claim 1 , further comprising forming the metal foam such that the metal foam has a metal matrix comprising between 5 and 20 percent of the volume of the metal foam. 
   
   
       5 . The method according to  claim 4 , further comprising forming the metal foam such that the metal foam has a metal matrix comprising between 8 and 10 percent of the volume of the metal foam. 
   
   
       6 . The method according to  claim 1 , further comprising forming the metal foam by a metal matrix based on AlSi7. 
   
   
       7 . The method according to  claim 6 , further comprising forming the metal foam such that the average density of the metal foam is approximately 0.5 g/cm 3 . 
   
   
       8 . The method according to  claim 6 , further comprising choosing a powder mixture as starting material for the metal foam such that a blowing agent will generate a foam volume of approximately five times that of the starting material under the effect of heat. 
   
   
       9 . The method according to  claim 1 , further comprising completely filling the valve stem and the valve cone with metal foam. 
   
   
       10 . The method according to  claim 1 , further comprising forming a metal envelope forming the valve by welding together a plurality of portions, which are made of like or unlike materials. 
   
   
       11 . The method according to  claim 10 , further comprising forming a valve head by joining the valve cone made in one piece with the valve stem as well as a valve sealing plug. 
   
   
       12 . The method according to  claim 10 , further comprising forming the valve stem by joining by friction welding a portion of Nimonic80A at the head end of the valve as well as an end portion of hardenable material surrounding the stem end of the valve. 
   
   
       13 . The method according to  claim 12 , further comprising making the end portion with X45CrSi93 (DIN 1.4718). 
   
   
       14 . A method for manufacturing a valve for control of gas exchange, suitable for internal combustion engines, the valve comprising a valve cone at one end of a valve stem, the valve stem and/or valve cone being formed as hollow metal parts having a cavity filled at least partly with metal foam to form a metal-foam body, wherein the metal-foam body formed in the valve cavity is bonded metallically at the molecular level at the interfaces with the hollow metal parts forming the valve with the metal-foam body bonding directly to the metal parts forming the valve, the method comprising:
 introducing starting material for the metal foam through one open end of the valve stem in such a way that the metal foam completely fills the valve cavity and molecularly bonds directly with the valve under the effect of heat, and its quantity is adjusted to swell beyond the filling end;   removing the excess quantity of metal foam; and   sealing the filling opening.   
   
   
       15 . The method according to  claim 14 , further comprising processing the metal foam in such a way that the metal foam has open pores, and further comprising filling the open pores with a coolant. 
   
   
       16 . The method according to  claim 14 , further comprising forming the metal foam such that the metal foam has a metal matrix comprising between 5 and 20 percent of the volume of the metal foam. 
   
   
       17 . The method according to  claim 16 , further comprising forming the metal foam such that the metal foam has a metal matrix comprising between 8 and 10 percent of the volume of the metal foam. 
   
   
       18 . The method according to  claim 14 , further comprising forming the metal foam such that the average density of the metal foam is approximately 0.5 g/cm3. 
   
   
       19 . The method according to  claim 14 , further comprising forming the metal foam by a metal matrix based on AlSi7. 
   
   
       20 . The method according to  claim 14 , further comprising choosing a powder mixture as starting material for the metal foam such that a blowing agent will generate a foam volume of approximately five times that of the starting material under the effect of heat.