PISTON OF INTERNAL COMBUSTION ENGINE, FILM THICKNESS MEASUREMENT METHOD FOR PISTON OF INTERNAL COMBUSTION ENGINE, AND MANUFACTURING METHOD FOR PISTON OF INTERNAL COMBUSTION ENGINE

摘要

To provide a piston of an internal combustion engine where a film having thermal properties different from those of a piston body part is provided on a crestal plane on a combustion chamber side, and which can easily measure a thickness of a film.SOLUTION: A piston comprises a piston body part and a film. The film has a film body part and a recess part for film thickness measurement. The recess part for film thickness measurement is opened toward a combustion chamber, and has a bottom part, an opening edge part, and a peripheral wall part between the bottom part and the opening edge part. At least a part of the opening edge part and peripheral wall part is composed of the film body part. The bottom part has a reference surface for film thickness measurement in at least a part of which the film body part does not exist.SELECTED DRAWING: Figure 1