Fuel Injector for a Gaseous Fuel

A fuel injector (1) for a gaseous fuel and comprising:

• an injection nozzle (3);
• a support body (4) with a tubular shape, which has a longitudinal axis (2) and is provided therein with a feeding channel (5) ending in the injection nozzle (3);
• an injection valve (7), configured to adjust the gaseous fuel flow through the injection nozzle (3) and provided with a movable shutter (9) arranged outside the support body (4) and with a valve seat (10) obtained in the support body (4);
• a tubular sleeve (12), arranged around an end part of the support body (4), entirely contains the shutter (9) therein, and ends with the injection nozzle (3);
• and
• an actuator (6), configured to move the shutter (9) between a closed position of the injection valve (7), in which the shutter (9) is pressed against the valve seat (10), and an open position of the injection valve (7), in which the shutter (9) is separate from the valve seat (10);
• wherein the shutter (9) comprises a first portion which faces the valve seat (10) and is shaped so as to be sealingly coupled to an inner surface of the valve seat (10) when the injection valve (7) is in the closed position, and a second portion which faces an inner surface of the sleeve (12) and always remains at a given distance from the inner surface of the sleeve (12);
• wherein the inner surface of the valve seat (10) and the inner surface of the sleeve (12) delimit an annular injection duct (14), an initial part of which is created when the injection valve (7) is in the open position and along which the gaseous fuel flows towards the injection nozzle (3) when the injection valve (7) is in the open position;
• wherein the injection duct (14), which is created when the injection valve (7) is in the open position, has a converging initial segment, in which an area of the injection duct (14) progressively decreases from a first maximum value at the beginning of the injection duct (14) to a minimum value, and an at least initially diverging final segment, in which the area of the injection duct (14) increases from the minimum value until reaching a second maximum value.