Piston formed by powder metallurgical methods

Abstract

A piston includes a piston structure being unitarily formed in a powder metallurgy process, the piston structure having a crown assembly and a skirt assembly, at least a partial combustion chamber being formed intersecting a piston crown surface during the powder metallurgy process, the skirt assembly depending from the crown assembly and having two spaced apart pin bosses, each pin boss having a pin bore defined therein, a pair of opposed semi-circular skirt members, each skirt member extending outwardly from and being integrally joined to both of the pin bosses. The piston may be formed by executing a powder metallurgy process on at least two different metallic constituents to define a non-homogenous piston structure. A method of forming a piston is further included.

1 . A piston, comprising: 
 a piston structure being unitarily formed in a powder metallurgy process, the piston structure having a crown assembly and a skirt assembly, at least a partial combustion chamber being formed intersecting a piston crown surface during the powder metallurgy process, the skirt assembly depending from the crown assembly and having two spaced apart pin bosses, each pin boss having a pin bore defined therein, a pair of opposed semi-circular skirt members, each skirt member extending outwardly from and being integrally joined to both of the pin bosses.    
   
   
       2 . The piston of  claim 1 , a void being defined between the crown assembly and the skirt assembly.  
   
   
       3 . The piston of  claim 2 , the void being defined between a skirt member upper margin and an undercrown of the crown assembly.  
   
   
       4 . The piston of  claim 1  being formed of a homogenous material.  
   
   
       5 . The piston of  claim 4 , the homogenous material forming a bearing surface of each pin bore for rotatably supporting a wrist pin.  
   
   
       6 . The piston of  claim 4 , a bearing formed separately of a material distinct from the homogenous material being disposed in each pin bore in a secondary operation for supporting a wrist pin.  
   
   
       7 . The piston of  claim 1 , the piston structure being unitarily formed in a powder metallurgy process with at least two different metallic constituents providing dissimilar characteristics at discrete locations of the piston structure.  
   
   
       8 . The piston of  claim 7 , a one of the at least two different metallic constituents presenting a bearing surface defining an inner margin of each pin bore.  
   
   
       9 . A piston, comprising: 
 non-homogenous piston structure being unitarily formed in a powder metallurgy process with at least two different metallic constituents providing dissimilar characteristics at discrete locations of the structure.    
   
   
       10 . The piston of  claim 9 , a one of the at least two different metallic constituents presenting a bearing surface defining an inner margin of each of two pin bores.  
   
   
       11 . The piston of  claim 9 , including, the piston structure having a crown assembly and a skirt assembly, at least a partial combustion chamber being formed intersecting a piston crown surface during the powder metallurgy process, the skirt assembly depending from the crown assembly and having two spaced apart pin bosses, each pin boss having a pin bore defined therein, and having a pair of opposed semi-circular skirt members, each skirt member extending outwardly from and being integrally joined to both of the pin bosses.  
   
   
       12 . The piston of  claim 11 , a void being defined between the crown assembly and the skirt assembly.  
   
   
       13 . The piston of  claim 12 , the void being defined between a skirt member upper margin and an undercrown of the crown assembly.  
   
   
       14 - 20 . (canceled)