Patent ID: 7971568

Claim:
A piston of a gasoline direct engine, comprising: a protuberance portion that protrudes upwards from an upper surface of the piston along a convexly circular arc shape having a radius (R 1 ) that is about the same as a piston diameter (D) in an axis of a piston center (SP) to have a predetermined height (T) from the upper surface of the piston, and distal edge portion of the protuberance portion is concavely rounded to be connected with the upper surface; a bowl (B) that has a bottom surface (F 1 ) dented downwards from the upper surface of the piston, wherein the bowl (B) has an asymmetrical ellipse shape from a center portion of the protuberance portion to an intake side direction of the piston, the bottom surface of the bowl (B) becomes deeper in an exhaust side direction of the piston to have a predetermined slope angle (θ1), and an inner wall portion formed deepest in the bottom surface of the bowl (B) has a concavely circular arc shape to form a predetermined rising angle (θ2) at a tip portion thereof; and trumpet portions (TR), one edges of which are connected to edge ends (E) of the protuberance portion and the other edges of which are expanded in the intake side direction of the piston to be connected to the bowl (B).