Patent ID: 7677478

Claim:
A fuel injector for direct injection of fuel into a combustion chamber of an internal combustion engine, comprising: an energizable actuator; a valve needle in operative connection with the energizable actuator; a sealing seat formed by a valve-closure member and a valve-seat surface of a valve-seat member, wherein the valve-seat member includes a plurality of spray-discharge orifices; and a restoring spring acting on the valve needle in a closing direction to actuate the valve-closure member; wherein the pressure of fuel flowing through the fuel injector is greater than 10 bar; wherein a diameter of the spray-discharge orifices increases along a discharge direction of the fuel to form a widened region; wherein the diameter of the spray-discharge orifices increases in a stepwise manner; wherein the ratio of an overall length l of the spray-discharge orifices to a smallest diameter d of the spray-discharge orifices is l≦3d; wherein a fractional length l′ of the spray-discharge orifices extending from an inflow side to the widened region is such that the ratio of the fractional length l′ to a smallest diameter d of the spray-discharge orifice is l′≦3d; wherein the smallest diameter d is defined by the equation d = ( 4 · c π · n · p 0.5 ) 0.5 wherein c is a constant, n is the number of the spray-discharge orifices, and p is the pressure of fuel; and wherein 0.3≦c≦0.6 [mm 2 Mpa 0.5 ].