Reduced compression height piston and piston assembly therewith and methods of construction thereof

Abstract

A piston assembly and method of construction thereof for an internal combustion engine are provided. The assembly includes a piston head having an upper combustion wall with an undercrown surface and a ring belt region. The piston head has a floor with an upper surface and a bottom surface. The floor is spaced beneath the upper combustion wall in radial alignment with the ring belt region. A substantially enclosed, annular cooling gallery is bounded by the undercrown surface and the floor. A pair of pin bores depends directly from the floor of the cooling gallery. The assembly further includes a pin having ends configured for oscillating receipt in the pin bores. A pin bearing surface extends within the pin bores and between the pin bores in the lower surface of the floor. The assembly includes a connecting rod with an end fixed to the pin for conjoint oscillation therewith.

What is claimed is: 
     
         1 . A method of constructing a piston assembly, comprising:
 forming a piston head having an upper combustion wall, an annular ring belt depending from said upper combustion wall, a floor spaced below said upper combustion wall and extending inwardly from said annular ring belt and forming an annular cooling galley bounded by the upper combustion wall, the annular ring belt and the floor;   forming a pair of laterally spaced pin bosses depending from said floor and each having a pin bore for receiving a wrist pin;   forming a skirt as one integral piece with the piston head out of the same material;   forming an underside surface of the floor with a load bearing surface that extends uninterrupted from one of the pin bosses to the other for providing direct contact support to the wrist pin along the full length of the load bearing surface; and   installing the wrist pin in the pin bores such that it is supported by the pin bosses and further supported along the full span between the pin bosses by the load bearing surface.   
     
     
         2 . The method of  claim 1  including providing direct support to the wrist pin by the load bearing surface without an intervening bearing piece. 
     
     
         3 . The method of  claim 1  wherein the cooling gallery is formed from a single space. 
     
     
         4 . The method of  claim 1  wherein the cooling gallery is formed by two annular spaces.