Abstract: The metering servo valve comprises a valve body, an open/close element, and an electromagnet, and is housed in a shell of the injector. The electromagnet actuates a mobile armature for a travel defined by an arrest element, carried by the electromagnet, which is housed in a casing, fixed in the shell by means of a threaded ring nut. Said ring nut is screwed with a pre-set tightening torque on a thread of the shell. The casing has a resting surface designed to engage a shoulder of the shell. The surface is carried by an area of the casing designed to undergo deformation as a function of the tightening torque of the ring nut so as to enable fine adjustment of the travel of the armature.

Abstract: A metering servovalve for a fuel injector of an internal combustion engine has an electro-actuator and a fixed valve body, which defines a control chamber communicating with an inlet and with an outlet channel. The outlet channel has at least one calibrated restriction and exits through the lateral surface of an axial stem, on which a sleeve slides, in a substantially fluid-tight manner, to open/close the outlet channel and so vary the pressure in the control chamber. The outlet channel is closed by an end portion of the sleeve that is elastically deformable in a radially outward direction, under the thrust of the fuel pressure, to increase the diameter at which the seal against the valve body is formed, with respect to a non-deformed state, and to generate a radial unbalancing force on the sleeve upon opening when the outlet channel is closed.

Abstract: The metering servo valve comprises a valve body, an open/close element, and an electromagnet, and is housed in a shell of the injector. The electromagnet actuates a mobile armature for a travel defined by an arrest element, carried by the electromagnet, which is housed in a casing, fixed in the shell by means of a threaded ring nut. Said ring nut is screwed with a pre-set tightening torque on a thread of the shell. The casing has a resting surface designed to engage a shoulder of the shell. The surface is carried by an area of the casing designed to undergo deformation as a function of the tightening torque of the ring nut so as to enable fine adjustment of the travel of the armature.