Patent ID: 7856958

Claim:
A piston for an internal combustion engine, comprising: a top surface having a valve recess for avoiding interference with a valve and a tumble flow maintaining depression, wherein a region where the valve recess is formed and a region where the depression is formed are adjacent to each other, and an edge line defined between the region where the valve recess is formed and the region where the depression is formed includes a changing edge line along which a dimension of the depression in a width direction perpendicular to a tumble flow axis becomes smaller from a center in a direction along the tumble flow axis toward a piston outer periphery in the direction along the tumble flow axis, a constant edge line along which the dimension of the depression in the width direction is maintained to be generally constant toward the piston outer periphery in the direction along the tumble flow axis, and an inflection part connecting the changing edge line and the constant edge line.