Piston for internal combustion engine

A piston for an internal combustion engine having a crown portion and a skirt portion projecting downward from the crown portion, the skirt portion having a thrust-side skirt portion and an anti-thrust-side skirt portion with the thrust-side skirt portion being located along a first direction away from a piston pin and the anti-thrust-side skirt portion being located along a second direction, opposite to the first direction, from the piston pin, a solid lubricant resin layer made of a resin containing a solid lubricant is located on each of the thrust-side skirt portion and the anti-thrust-side skirt portion in a predetermined pattern, guide grooves for guiding lubricating oil are formed at a portion of each of the thrust-side skirt portion and the anti-thrust-side skirt portion where no solid lubricant resin layer is formed, comprising:

• a center portion in a width direction of each of the thrust-side skirt portion and the anti-thrust-side skirt portion is formed with the solid lubricant resin layer having no guide groove,
• each guide groove is formed from an end in the width direction of the center portion toward an end in the width direction of the thrust-side-skirt portion or the anti-thrust-side skirt portion,
• each guide groove has an open end, nearest the end in the width direction of the thrust-side skirt-portion or the anti-thrust-side skirt portion;
• and
• all the guide grooves of the thrust-side skirt portion having a shape inclined upward from the center portion toward the end in the width direction of the thrust-side skirt-portion, and being provided so as to move the lubricating oil existing in the vicinity of the end in the width direction of the thrust-side skirt-portion into the center portion when the piston moves upward,
• all the guide grooves of the anti-thrust-side skirt portion having a shape inclined downward from the center portion toward the end in the width direction of the anti-thrust-side skirt-portion, and being provided so as to move the lubricating oil existing in the vicinity of the end in the width direction of the anti-thrust side skirt-portion into the center portion when the piston moves downward, and
• the center portion is formed in a range within ±10° to ±40° with respect to a reference line set as 0° around intersection of the axis of the piston pin and the reference line is set as a center, the reference line being a line orthogonal to an axis of the piston pin and extending in a diametrical direction of the piston.