Patent ID: 7255289

Claim:
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 ).