Patent ID: 7234654

Claim:
A fuel injector for direct injection of fuel into a combustion chamber of an internal combustion engine, comprising: a valve seat body having a valve-seat surface; a valve-closure member, which cooperates with the valve-seat surface of the valve-seat body to form a sealing seat; and at least one spray-discharge orifice provided downstream from the sealing seat, which has a guide region and an exit region arranged at a discharge-side end, the exit region widening at least one of i) in a stepped manner by at least one first step, and ii) at least in part continuously, beginning with a transition from the guide region into the exit region; wherein a fuel jet, which emerges from the guide region at the transition and widens uniformly at a jet angle, passes the discharge-side end of the exit region while maintaining a gap between the fuel jet and an inner wall of the exit region, and, after a distance s, the gap having a dimension that is greater than zero, and wherein a first volume remains in the exit region between the fuel jet and the inner wall of the exit region, and wherein the first volume has a longitudinal cross-sectional area (Ag), and a coefficient (B) characterizing the first volume is calculated according to the following equation: B =  D · π · Ag   d · π · s  D being a first diameter between centers of mass of the longitudinal cross-sectional area Ag, d being a second diameter of the fuel jet at a midpoint of distance s, and the coefficient B being not smaller than 0.5 and not greater than 2.5.