Fuel Injector for a Gaseous Fuel

A fuel injector for a gaseous fuel and having: an injection nozzle; a support body with a tubular shape, which is provided with a feeding channel therein, ending in the injection nozzle; an injection valve; a tubular sleeve, which is arranged around an end part of the support body, entirely contains the shutter therein, and ends with the injection nozzle; and an actuator, which is configured to move the shutter. An injection duct, which is created when the injection valve is in the open position, has a converging initial segment, in which an area of the injection duct progressively decreases from a first maximum value at the beginning of the injection duct to a minimum value, and a diverging final segment, in which the area of the injection duct increases from the minimum value until reaching a second maximum value.