Patent ID: 7325525

Claim:
A piston for an internal combustion engine comprising: a fuel injection mechanism injecting a fuel into a cylinder, wherein said fuel injection mechanism injects the fuel from a side of a cylinder head into a cylinder bore, and wherein said piston includes: a cavity provided at a top end of said piston that is formed asymmetrically relative to the center axis of the piston and to which a spray of the fuel injected from said fuel injection mechanism strikes, a piston pin boss provided at a back end of said piston, the piston pin boss having a hole through which a piston pin for coupling said piston to a connecting rod is inserted, and a thickness-reduction portion provided at the back end of said piston and adjacent to said piston pin boss, a thickness-reduction amount of said thickness-reduction portion being set in correspondence with a position of said cavity, the thickness-reduction portion comprising a first thickness-reduction section under the cavity and a second thickness-reduction section not under the cavity, the thickness-reduction amount of the first thickness-reduction section being different from the thickness-reduction amount of the second thickness-reduction section.