Abstract: An electromagnetic fuel injector having: a tubular support body; an injection nozzle arranged at an end of the support body; an injection valve coupled to the injection nozzle; a plunger, which is movable, so as to adjust the fuel flow through the injection nozzle, between a closed position and an open position of the injection valve; an electromagnetic actuator provided with a main electromagnet configured, when it is activated, to apply a force to the plunger, which pushes the plunger towards the open position of the injection valve and with a secondary electromagnet configured, when it is activated, to apply a force to the plunger, which pushes the plunger towards the closed position of the injection valve; and a closing spring configured to push the plunger towards the closed position of the injection valve.

Abstract: An electromagnetic fuel injector having: a tubular support body; an injection nozzle arranged at one end of the support body; an injection valve coupled to the injection nozzle; a plunger, which is movable, so as to adjust the fuel flow through the injection nozzle, between a closed position and an open position of the injection valve; an electromagnetic actuator provided with at least one main electromagnet and at least one secondary electromagnet; and a closing spring configured to push the plunger towards the closed position of the injection valve. The secondary electromagnet has a secondary coil and a secondary movable armature, which is arranged inside the support body, is movable, is integral to the plunger and is magnetically coupled to the secondary coil but lacks a secondary fixed armature, which is integral to the support body, is arranged inside the support body and is magnetically coupled to the secondary movable armature so as to magnetically attract the secondary movable armature.

Abstract: A method for the production of a separation microcolumn made in silicon wafer (11), for a chromatographic or gas-chromatographic system, is described. According to the method, a micro-trench (14) is first made in the silicon wafer. The micro-trench extends in depth in the silicon wafer (11) and along the entire path of the microcolumn. Then, a perfectly circular micro-channel (20), tangent to the upper surface of the silicon wafer (11), is obtained by an in-depth isotropic etching with reactive ions in the micro-trench (14). The microcolumn is functionalized by applying a stationary phase (SP) to the inner wall and finally, another wafer or a layer (17) of silicon or silicon oxide or polymeric material, that acts as a cap or cover, is applied onto the silicon wafer, thus closing the micro-channel. According to a variation, the functionalization is carried out after the micro-channel closure.