Patent ID: 7980492

Claim:
A fuel injector comprising: an injection valve comprising an injection nozzle; a mobile needle for regulating fuel flow through the injection valve and ending with a shutting head, which engages a valve seat of the injection valve, and is arranged externally with respect to the injection valve and presents a predetermined sealing diameter; an actuator for displacing the needle between a closing position and an opening position of the injection valve; a closing spring which tends to maintain the needle in the closing position of the injection valve pushing the shutting head against the valve seat itself in a sense contrary to a feeding sense of fuel; and a supporting body having a tubular shape and presenting a feeding channel within which the needle is arranged; a sealing body, wherein the valve seat of the injection valve is defined and which fluid-tightly closes the feeding channel; a stopper element, which is integral with the needle and abuts against an upper surface of the sealing body when the needle is in the opening position of the injection valve so as to determine stroke length of the needle; a balancing channel, which is aligned with the mobile needle, is at ambient pressure, and ends with a recirculation pipe of the fuel at ambient pressure; wherein the needle, at an opposite end of the shutting head, is provided with a closing piston, which is at least partially and slidingly inserted in the balancing channel so as to slide along the balancing channel; wherein the balancing channel is not completely hydraulically isolated from the feeding channel due to a leakage from the fuel which leaks from between an internal wall of the balancing channel and an external wall of the closing piston and is recovered by the recirculation pipe.