Patent ID: 8286897

Claim:
An electromagnetic fuel injector comprising: an injection nozzle controlled by an injection valve; a movable shutter to regulate the flow of fuel through the injection valve; a tubular body provided with a cylindrical seat that acts as a fuel duct and houses the shutter; and an electromagnetic actuator, which moves the shutter between a closed position and an open position of the injection valve and comprises a fixed magnetic pole, a coil to induce a magnetic flux in the magnetic pole when the actuator is activated, a movable anchor suitable to be magnetically attracted by the magnetic pole; and a tubular magnetic armature, which is made of ferromagnetic material and is arranged outside the tubular body; wherein the tubular magnetic armature is comprised of at least two annular components which are initially separate from one another; the two annular components being joined together one inside the other so as to vary the relative axial position between the two annular components and to thereby adjust the overall magnetic reluctance of the magnetic circuit traversed by the magnetic flux and thus regulate the force of magnetic attraction generated on the anchor; wherein an outer annular component has a tubular truncated cone-shaped lower portion with an inside diameter greater than an outside diameter of the tubular body so as to define an annular chamber therebetween; and wherein an inner annular component having a tubular truncated cone shape which positively reproduces the shape of the lower portion of the outer annular component and gradually enters the annular chamber so as to gradually vary the relative axial position between the inner and outer annular components.