Patent ID: 7546961

Claim:
A fuel injector ( 1 ) comprising: an injection valve ( 7 ) comprising an injection jet ( 3 ) and provided with a plunger ( 15 ), which is mobile in order to control the flow of fuel and ends with a sealing head ( 22 ); an electromagnetic actuator ( 6 ) capable of displacing the plunger ( 15 ) between a closed position and an open position of the injection valve ( 7 ) and comprising a coil ( 11 ), a fixed magnetic armature ( 12 ), and an armature ( 9 ), which is attracted magnetically by the magnetic armature ( 12 ) and is mechanically connected to the plunger ( 15 ); a main spring ( 10 ) for holding the plunger ( 15 ) in the closed position of the injection valve ( 7 ) and having one end resting against the armature ( 9 ); a calibration spring ( 28 ), which comprises one end that rests against the armature ( 9 ) on the opposite side to the main spring ( 10 ); a support body ( 4 ) having a tubular shape and comprising a feed channel ( 5 ) within which are arranged the plunger ( 15 ) and the spring ( 10 ); and a plug body ( 17 ), in which is defined a valve seat ( 16 ) of the injection valve ( 7 ) in which the sealing head ( 22 ) engages; the plug body ( 17 ) comprises a disk-shaped plug element ( 18 ) which tightly seals the feed channel ( 5 ) at the bottom, and a guide element ( 19 ), which rises from the plug element ( 18 ), is tubular in shape, and accommodates within it the plunger ( 15 ); wherein the sealing head ( 22 )is of a frustoconical shape, is arranged externally relative to the guide element ( 19 ) and is thrust by the main spring ( 10 ) against said guide element ( 19 ) in a direction contrary to the direction of feed of the fuel; the valve seat ( 16 ) has a frustoconical shape which is a negative reproduction of the frustoconical shape of the sealing head ( 22 ) such that, in the open position of the injection valve ( 7 ), the sealing head ( 22 ) is separated from the valve seat ( 16 ), so creating an opening which permits passage of the fuel of a circular, ring-shaped section and a frustoconical shape in order to impart an internally hollow conical shape to the injected fuel; wherein the armature ( 9 ) comprises an annular element ( 24 ) and a discoidal element ( 25 ) which closes the annular element ( 24 ) at the top, has a central through-hole ( 26 ) capable of receiving an upper portion of the plunger ( 15 ), has a plurality of peripheral through-holes ( 27 ) capable of permitting fuel to flow towards the injection jet ( 3 ), has an upper wall against which rest one end of the calibration spring ( 28 ), and has a lower wall opposite to the upper wall against which rest one end of the main spring ( 10 ).