Patent ID: 8061632

Claim:
A fuel injector for internal combustion engines comprising: a fuel feeding channel having an axis and an injection outlet; an injection valve controlling flow through the injection outlet; the injection valve including a shutter arranged inside the fuel feeding channel to define, within the fuel feeding channel, a first fuel introduction section (A 1 ), the shutter being movable from and to a closing position along the feeding channel, and a second section (A 2 ); and a sealing seat arranged adjacent an end of the fuel feeding channel upstream of the outlet; an elastic member that biases the shutter in a closing position; and an actuator mechanism connected to the shutter to displace the shutter away from the closing position and to an opening position of the outlet; wherein a hydraulic resistance is arranged along the fuel feeding channel upstream of the sealing seat to balance forces acting upon the shutter; and wherein the hydraulic resistance is constructed so as to determine, along the fuel feeding channel and upstream of the sealing seat, a pressure drop so that the shutter is subjected, when spaced from the closing position, to two antagonist hydraulic forces F 1 and F 2 such as to satisfy the equation: F1 =A 1 ×P 1 =F 2 =A 2 ×P 2 , wherein: A 1 =area of the first section; P 1 =fuel feeding pressure; A 2 =area of the second section; and P 2 =fuel pressure inside the feeding channel and downstream of the hydraulic resistance means.