PISTON FOR INTERNAL COMBUSTION ENGINE

摘要

On a piston top surface, a cavity and two valve recesses are formed. On the piston top surface, a first heat insulating film is formed. However, on edge portions, a second heat insulating film different from the first heat insulating film is formed. The second heat insulating film is formed along the edge portions. The first heat insulating film is composed of porous alumina and a sealer. The second heat insulating film is composed of only porous alumina.

主权项

1. A piston for an internal combustion engine comprising a piston main body, a cavity formed on a top surface of the piston main body, and a heat insulating film that is formed on the top surface, and has a lower thermal conductivity and a lower heat capacity per unit volume than an aluminum alloy that is used as a base material of the piston main body,
wherein the heat insulating film comprises a low heat insulation film that is formed on a cavity edge portion forming a boundary between the cavity and the top surface and is composed of alumina having a number of pores that are opened to the top surface, and a high heat insulation film that is formed on a surface inward from the cavity edge portion and a surface surrounding the cavity edge portion, and is composed of alumina having a number of pores that are opened to the top surface and a sealer that is provided to cover the openings of the number of pores.