Vehicle piston internal combustion engine comprising an adapted recess

A combustion process of a piston internal combustion engine (10) with at least one cylinder and a piston (1) in the cylinder, wherein the piston has a recess (2), and with a cylinder head, which has a roof shape that is complementary to a roof-shaped geometry of the piston (1) and that has a first and a second side intersecting in the shape of a gable, wherein the piston (1) and the cylinder head define a top and a bottom side of a combustion chamber, with an ignition device, which is arranged at least approximately in the center of the roof shape, and with preferably two inlet valves (5), which are arranged in the first side (6), and with preferably two outlet valves (4), which are arranged in the second side (7), wherein the recess (2) extends over both sides, wherein the recess (2) comprises sides descending approximately vertically at the sides and a base, and the piston has at least two, preferably four quench zones, which are separated at least partially from each other by valve pockets for valves, the process comprising the steps of:

• breaking up a global tumbling motion of a flow in a combustion space during a compression stroke using edges formed at least by a recess (2) in a piston base, the breaking up of the global tumbling motion of the flow producing a turbulent flow;
• flowing the turbulent flow into a narrowing gap between a piston roof and quench zones in the piston base;
• flowing the turbulent flow out of the narrowing gap between the piston roof and quench zones in the piston base before the piston reaches TDC;
• and
• continuing to flow fuel into and out of the narrowing gap between the piston roof and quench zones, in which at TUC a compression ratio between 11 and 16 is set in the combustion space.