Fuel injector for an internal-combustion engine

A fuel injector (1) for an internal-combustion engine, said injector comprising:

• a) an outer shell (2) elongated along an axis (3), defining an inlet for supply of said fuel and comprising a first axial terminal portion (4) and a second axial terminal portion (5) opposite to one another, said second axial terminal portion (5) being provided with a nozzle (9) communicating with said inlet (7) and being designed to be housed in said engine;
• b) an electrically controlled actuator (16);
• c) a servo valve (15) comprising:
• i) an axial seat (27), fixed with respect to said shell (2);
• ii) an open/close element (32) which can slide axially, under the action of said actuator (16) and in a substantially fluid-tight way, in said seat (27) under the action of said actuator (16);
• iii) a control chamber (23), communicating with said inlet (7) and having an outlet channel (25) giving out into an annular chamber (34) made radially between the side surfaces of said seat (27) and of said open/close element (32), so as to render the resultant of the axial actions of pressure on said open/close element (32) substantially zero;
• d) a pin (11), which can move in response to the pressure of said control chamber (23) for opening/closing said nozzle (9);
• said first terminal portion (4) having, in the radial direction, dimensions greater than those of said second terminal portion (5);
• said servo valve (15) and said actuator (16) being housed in said first terminal portion (4).