Electromagnetic fuel injector with two independent coil and related control method

Abstract

To provide an electromagnetic fuel injector having a low noise level and modest degradation (wear).SOLUTION: An electromagnetic fuel injector 1 comprises a tubular support body 4, an injection nozzle disposed at an end of the support body, an injection valve coupled to the injection nozzle, a plunger 8, and an electromagnetic actuator 6. The electromagnetic actuator is provided with a main electromagnet 11, a secondary electromagnet 12, and a closing spring. The main electromagnet is configured to, when it is activated, apply a force for pushing the plunger towards the open position of the injection valve. The secondary electromagnet is configured to, when it is activated, apply a force for pushing the plunger towards the closed position of the injection valve. The closing spring is configured to push the plunger towards the closed position of the injection valve.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This patent application claims priority to Italian Patent Application No. 102023000014394, filed on July 10, 2023, the entire disclosure of which is incorporated herein by reference.

[0002] The present invention relates to an electromagnetic fuel injector and an associated control method.

[0003] The present invention is advantageously applied to electromagnetic hydrogen injectors, and the following discussion makes explicit reference to electromagnetic hydrogen injectors without any loss of generality. [Background technology]

[0004] Typically, an electromagnetic fuel injector (such as that described in US Pat. No. 5,399,363) comprises a cylindrical tubular support having a central supply channel, which ends in an injection nozzle acting as a fuel duct and adjusted by an injection valve controlled by an electromagnetic actuator. The injection valve comprises a plunger which is moved by the action of the electromagnetic actuator between the closed and open positions of the injection nozzle against the action of a closing spring which pushes the plunger towards the closed position. The plunger ends in a shutter head adapted to seal against a valve seat of the injection valve.

[0005] The electromagnetic actuator comprises: (at least one) coil arranged in a fixed position outside and around the support; a movable armature made of a ferromagnetic material that is firmly connected to the plunger and movably mounted inside the support; and a fixed armature (or bottom) made of a ferromagnetic material that is arranged inside the support in the region of the coil and is adapted to magnetically attract the armature when the coil is excited.

[0006] When liquid fuel is injected, the presence of the liquid fuel inside the support constitutes an obstacle in relation to the movement of the movable armature, and in effect forms a hydraulic damper that limits the speed of movement of the movable armature. On the other hand, when gaseous fuel is injected (especially hydrogen, which is a very light gas), the presence of the gaseous fuel inside the support does not constitute an obstacle in relation to the movement of the movable armature, which therefore moves at high speed and crashes violently against the armature at the end of the opening movement. The violent crash of the movable armature against the armature at the end of the opening movement causes both a high noise level and accelerated deterioration (wear). Moreover, the violent crash of the movable armature against the armature at the end of the opening movement also causes an associated rebound phenomenon that introduces a certain element of randomness into the amount of fuel injected.

[0007] In this respect, it is important to note that hydrogen has a low density (having a very simple molecule consisting of only two hydrogen atoms) and therefore, in order to be able to inject a sufficient amount (mass) of hydrogen into the combustion chamber, it is necessary to inject a corresponding amount of hydrogen, which in particular requires a large area of ​​passage of the hydrogen through the injector (i.e. the opening through which the hydrogen must pass to leave the hydrogen injector must be large). In order to have a large area of ​​passage of the hydrogen through the injector, it is necessary for the plunger (and therefore the movable armature) to have a long distance movement between the closed and open positions, which causes a further increase in the impact velocity of the movable armature against the armature at the end of the opening movement.

[0008] In order to limit the impact speed of the movable armature against the armature at the end of the opening movement, a specific current profile is currently used through the coils of the electromagnetic actuator, which should make it possible to reduce the magnetic force attracting the movable armature towards the armature when the movable armature is close to the armature. However, the control of the magnetic force attracting the movable armature towards the armature when the movable armature is close to the armature is very complicated and not very accurate, since in this position the magnetic force attracting the movable armature towards the armature has a strong nonlinearity (i.e. it increases exponentially when the air gap between the movable armature and the armature becomes very small).

[0009] Patent Document 2 describes a fuel injector for a diesel engine, the fuel injector including a throttling needle valve for closing an injection passage, an armature attached to the needle valve, an opening electric solenoid for applying an induction magnetic field to the armature which moves the armature toward an open position of the injection passage, and a closing electric solenoid for applying an induction magnetic field to the armature which moves the armature toward a closed position of the injection passage. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] European Patent Application Publication No. 1611384 [Patent Document 2] DE 10101060 A1 Summary of the Invention

[0011] The object of the present invention is to produce an electromagnetic fuel injector which does not have the above mentioned drawbacks, i.e. which has a low noise level and is subject to low deterioration (wear) whilst at the same time being easy and cost effective to manufacture.

[0012] According to the present invention there is provided an electromagnetic fuel injector and associated control method as claimed in the accompanying claims.

[0013] The appended claims, which form an integral part of this specification, illustrate preferred embodiments of the invention.

[0014] The invention will now be described with reference to the accompanying drawings, which show non-limiting exemplary embodiments of the invention. [Brief description of the drawings]

[0015] [Figure 1] 1 is a longitudinal cross-sectional view of a portion of a fuel injector made in accordance with the present invention; [Diagram 2] FIG. 2 is a view on an enlarged scale of a detail of FIG. 1. [Diagram 3] 2 is a graph showing the change in position of the movable assembly and the activation of two electromagnets of the fuel injector of FIG. 1 over time during the opening and subsequent closing of the injector; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] In Figure 1, reference number 1 indicates generally an electromagnetic gaseous fuel (particularly hydrogen) injector having cylindrical symmetry about a longitudinal axis 2 and adapted to be controlled to inject hydrogen through an injection nozzle 3. The injection nozzle 3 injects directly into the combustion chamber (not shown) of a cylinder of an internal combustion engine.

[0017] The electromagnetic injector 1 comprises a support 4 having a cylindrical tubular shape with a cross-section that varies along the longitudinal axis 2 and having a supply channel 5 extending along the entire length of the support 4 for supplying pressurized hydrogen towards an injection nozzle 3.

[0018] The support 4 houses an electromagnetic actuator 6 and an injector 7. In use, the injector 7 is operated by the electromagnetic actuator 6 in order to regulate the flow of hydrogen through the injection nozzle 3 available in the region of the injector 7.

[0019] The electromagnetic actuator 6 is configured to move axially (i.e. along the longitudinal axis 2) a movable assembly comprising a plunger 8 which ends in a shutter 9. The shutter 9 cooperates with a valve seat of the injector 7 in order to regulate the flow of hydrogen through the injection nozzle 3. In other words, the support 4 ends in a (at least one) through-hole, in which the valve seat is defined and which is engaged by the shutter 9. In particular, the electromagnetic actuator 6 is configured to move the shutter 9 between a closed position and an open position of the injector 7. Furthermore, the electromagnetic actuator 6 is coupled to a closing spring 10 which keeps the electromagnetic injector 1 normally closed. The closing spring 10 thus presses the shutter 9 towards the closed position of the injector 7. In other words, the injector 7 is normally closed by the effect of the closing spring 10 which presses the plunger 8 towards the closed position, in which the shutter 9 of the plunger 8 is pressed against the valve seat of the injector 7.

[0020] In the embodiment shown in the attached drawings, the injector 7 opens with an axial inward movement and preferably the shutter 9 has a spherical shape. According to a different embodiment not shown, the injector 7 opens with an axial outward movement and preferably the shutter 9 has a frusto-conical shape.

[0021] As better shown in Fig. 2, the electromagnetic actuator 6 comprises an independently controlled main electromagnet 11 and a secondary electromagnet 12. The main electromagnet 11 is configured to exert a force on the plunger 8 (when activated) that opens the injector 7 (thus countering the elastic force generated by the closing spring 10), while the secondary electromagnet 12 is configured to exert a force on the plunger 8 (when activated) that closes the injector 7 (thus in harmony with the elastic force generated by the closing spring 10). In other words, the two electromagnets 11 and 12 are configured to exert forces on the plunger 8 that are opposite to each other.

[0022] The main electromagnet 11 comprises a main coil 13 housed outside the support 4 and a main armature 14 (magnetic pole or bottom or magnetic extension) made of magnetic material. The main armature 14 is housed inside the support 4 in a fixed position in the region of the main coil 13 and has a central hole 15 that allows the fuel to flow towards the injection nozzle 3. This armature 14 is thus inserted inside the support 4 and is integrated into it (typically it is welded to the support 4).

[0023] The secondary electromagnet 12 comprises a secondary coil 16 housed outside the support 4 and a secondary armature 17 (magnetic pole or bottom or magnetic extension) made of magnetic material. The secondary armature 17 is housed inside the support 4 in a fixed position in the region of the secondary coil 16 and has a central hole 17 that allows the fuel to flow towards the injection nozzle 3. This armature 17 is i.e. inserted inside the support 4 and integrated into it (typically it is welded to the body 4).

[0024] In the embodiment illustrated in the accompanying drawings, a single armature 19 is provided. This armature 19 is integrated with the plunger 8 (i.e. is part of the moving assembly), is located between the two armatures 14 and 17 and is shared by both the electromagnets 11 and 12. That is, this armature 19 is magnetically coupled to both the main coil 13 and the secondary coil 17, i.e. is magnetically coupled to the main coil 13 as it is traversed by the magnetic flux generated by the main coil 13, and is magnetically coupled to the secondary coil 17 as it is traversed by the magnetic flux generated by the secondary coil 17. That is, the magnetic field generated by energizing the main coil 13 attracts the armature 19 towards the main armature 14, and similarly, the magnetic field generated by energizing the secondary coil 16 attracts the armature 19 towards the secondary armature 17. According to a different embodiment, not shown, each electromagnet 11 or 12 is provided with its own armature 19, and thus the two armatures 19 are provided separate and independent of each other and both are integrated in the plunger 8 (i.e. are part of the movable assembly). In this embodiment, each electromagnet 11 or 12 magnetically attracts only said corresponding armature 19.

[0025] The electromagnetic injector 1 comprises (is connected to) a control unit 20 (schematically shown in FIG. 1 ), which powers the two coils 13 and 16 of the two electromagnets 11 and 12 independently of each other, i.e. the control unit 20 drives (powers) the main coil 13 of the main electromagnet 11 independently of the secondary coil 16 of the secondary electromagnet 12. In particular, the control unit 20 comprises a controller 21 connected only to the main coil 13 for powering only the main coil 13, and a controller 22 connected only to the secondary coil 16 for powering only the secondary coil 16.

[0026] In other words, the electromagnets 11 and 12 are independently controlled, i.e. the two coils 13 and 16 are not connected in series or parallel to each other, but are powered by two different controllers 21 and 22, since they are passed by different or differentiated currents (this will be explained better below).

[0027] In use, when the electromagnets 11 and 12 are de-energized, the armature 19 is not subjected to any force of magnetic origin and is therefore subjected only to an elastic force generated by the closing spring 10 which pushes the armature 19 together with the plunger 8 towards the closed position (i.e. downwards). In this situation, the injector 7 is closed. Preferably, in the closed position, the armature 19 is close to (in the vicinity of) the secondary armature 17 but is not in contact with it, i.e. there is a free space between the armature 19 and the secondary armature 17 (as a result, the "stop" of the closed position is established by the contact of the shutter 9 against the valve seat of the injector 7 and not by the contact of the armature 19 against the secondary armature 17).

[0028] In use, to open the injector 7, the main electromagnet 11 is activated (i.e. the main coil 13 is energized) so that it generates a magnetic force that overcomes the elastic force of the closing spring 10 and attracts the armature 19 towards the main armature 14 (i.e. towards the open position). As a result, the armature 19 moves towards the main armature 14 (i.e. towards the open position), and the gradual opening of the injector 7 is determined. When the armature 19 is close to the main armature 14 (i.e. close to the open position), the secondary electromagnet 12 is also activated (i.e. the secondary coil 16 is energized) so that it generates a magnetic force that attracts the armature 19 towards the armature 17. As a result, the movement of the armature 19 towards the main armature 14 (i.e. towards the open position) is decelerated. It is important to note that the magnetic force generated by the secondary electromagnet 12 is not (i.e. is not strong enough to) stop or reverse the movement of the armature 19 towards the primary armature 14 (i.e. towards the open position), but only has the effect of slowing down (braking) the movement of the armature 19 towards the primary armature 14 (i.e. towards the open position). Thus, at the end of the opening step, the armature 19 finishes its movement relative to the primary armature 14 (the "stop" of the open position is established by the contact of the armature 19 with the primary armature 14) and the armature 19 impacts with a significantly smaller speed against the primary armature 14 due to the effect of the deceleration (braking) action exerted by the secondary electromagnet 12 (more generally, the "stop" of the open position is established by the contact of an element of the mobile assembly with a fixed element integrated in the support 4).

[0029] Once the armature 19 has come into contact with the main armature 14, only the main electromagnet 11 is kept active to keep the injector 7 open (typically by supplying a lower intensity current to the main coil 13, since a reduced magnetic force is sufficient to maintain the open position), while the secondary electromagnet 12 is switched off (since its function is useless when the armature 19 is stationary and in contact with the main armature 14).

[0030] In use, to close the injector 7, the main electromagnet 11 is switched off, the armature 19 is no longer subjected to any forces of magnetic origin and is pushed towards the closed position (i.e. downwards) by the elastic force generated by the closing spring 10, the armature 19 detaches from the main armature 14 and moves towards the secondary armature 17 (which it never reaches, i.e. never comes into contact with the secondary armature 17, because a "stop" of the closed position is established by the contact of the shutter 9 against the valve seat of the injector 7 before the contact of the armature 19 against the secondary armature 17 occurs). Generally, the secondary electromagnet 12 remains switched off during the entire closing step, because the elastic force generated by the closing spring 10 is sufficient to quickly close the injector 7. According to an alternative embodiment, the secondary electromagnet 12 may be activated (by energizing the secondary coil 16) to increase the speed of the armature 19 towards the main armature 14, at least during the first part of the closing step, and thus speed up the closing step.

[0031] When the shutter 9 is close to the valve seat of the injector 7, the main electromagnet 11 is briefly activated (reactivated) (i.e. the main coil 13 is energized) and the main electromagnet 11 generates a magnetic force that attracts the armature 19 towards the main armature 14, as a result of which the movement of the armature 19 towards the closed position is slowed down. It is important to note that the magnetic force generated by the main electromagnet 11 at the end of the closing step is not (i.e. is not strong enough to) stop or reverse the movement of the armature 19 towards the closed position, but only has the effect of slowing down (or braking) the movement of the armature 19 towards the closed position. Thus, at the end of the closing step, when the shutter 9 collides against the valve seat of the injector 7, the armature 19 completes its movement (the "stop" of the closed position is established by the contact of the shutter 9 against the valve seat of the injector 7) and the shutter 9 collides against the valve seat of the injector 7 at a significantly smaller speed due to the effect of the deceleration (braking) action exerted by the main electromagnet 11.

[0032] The above is illustrated diagrammatically in Fig. 3, which shows in the upper region the time trends of the position of the movable assemblies (i.e. of the armature 19, of the plunger 8 and of the shutter 9) moving between a closed position ("closed") and an open position ("open"). In the middle region the time trends of the state of the primary electromagnet 11 are shown, which changes between a deactivated state ("off") and an active state ("on"), and in the lower region the time trends of the state of the secondary electromagnet 12 are shown, which changes between a deactivated state ("off") and an active state ("on").

[0033] As shown in FIG. 3, before time t1, the electromagnets 11 and 12 are turned off and the armature 19 (i.e., the movable assembly) is still in the closed position. At time t1, the main electromagnet 11 is activated, and at time t2 (due to the effects of electromagnetic and mechanical inertia), the main electromagnet 11 starts to move the armature 19 from the closed position toward the open position, and at time t5, the open position is reached. Between times t3 and t4, the secondary electromagnet 12 is also activated to decelerate (brake) the armature 19 near the open position (i.e., just before the armature 19 hits the main armature 14). The effect of the secondary electromagnet 12 is not instantaneous due to the effects of electromagnetic and mechanical inertia, and the secondary electromagnet 12 is deactivated before the armature 19 reaches the open position to form the effects of electromagnetic and mechanical inertia. At time t6, the main electromagnet 11 is deactivated, and at time t7, the action of the closing spring 10 (due to the effects of electromagnetic and mechanical inertia) pushes the armature 19 towards the closed position, at time t 10 The shutter 9 reaches the closed position at t8. Between times t8 and t9, the main electromagnet 11 is activated to decelerate (brake) the armature 19 which is close to the open position (i.e. just before the shutter 9 hits against the valve seat of the injector 7). The effect of the main electromagnet 11 is not instantaneous due to the effects of electromagnetic and mechanical inertia, and the main electromagnet 11 is deactivated before the armature 19 reaches the closed position so as to form the effects of electromagnetic and mechanical inertia.

[0034] According to a preferred embodiment, the electromagnets 11 and 12 are open loop controlled such that a pre-determined current trend (profile) is cycled through the respective coils 13 and 16. Self-calibration logic may be provided which estimates the actual opening and / or closing times of the injector 7 and can make corrections (if necessary) to the pre-determined current trend (profile) based on the actual opening and / or closing times of the injector 7.

[0035] According to a possible embodiment, the main electromagnet 11 remains switched off during the entire closing step (especially if the secondary electromagnet 12 also remains switched off).

[0036] According to an alternative embodiment, when the armature 19 is close to the "stop" of the closed position (established by the contact of the shutter 9 against the valve seat of the injector 7), the main electromagnet 11 is activated (i.e. the main coil 13 is energized) to generate a magnetic force that attracts the armature 19 towards the primary armature 14, thus slowing down the movement of the armature 19 towards the primary armature 14. It is important to note that the magnetic force generated by the main electromagnet 11 during the closing step cannot (i.e. is not strong enough to) stop or reverse the movement of the armature 19 towards the secondary armature 17, but only has the effect of slowing down (braking) the movement of the armature 19 towards the secondary armature 17. Thus, at the end of the closing step, the armature 19 finishes its movement when the shutter 9 comes into contact (impacts) with the valve seat of the injector 7 (i.e. reaches the "stop" of the closed position). This contact (impact) occurs at a fairly small speed due to the effect of the deceleration (braking) action exerted by the main electromagnet 11 .

[0037] According to a preferred embodiment, the two coils 13 and 16 are different from each other because they have to generate magnetic forces of different strengths in different conditions. The main coil 13 (combined with the main armature 14) must generate a magnetic force sufficient to overcome the elastic force of the closing spring 10 and attract the armature 19 towards the main armature 14, while the secondary coil 16 (combined with the secondary armature 17) must slow down (without stopping) the final part of the movement of the armature 19 towards the main armature 14. Therefore, the two coils 13 and 16 generally differ from each other in the number of turns and thus in shape and / or size.

[0038] To summarise what has been said above, the movable assembly (and thus the plunger 8 carrying the shutter 9) is subjected (in addition to the elastic force generated by the closing spring 10) to two mutually independent magnetic forces, since they are generated by two electromagnets 11 and 12 which are driven independently with respect to each other.

[0039] In the preferred embodiment described above, the electromagnetic injector 1 is configured to inject hydrogen, however, alternatively, the electromagnetic injector 1 may be configured to inject any other type of gaseous fuel, for example methane, or (typically when high injection flow rates are required, particularly requiring long distance travel of the plunger 8) liquid fuel or water.

[0040] The embodiments described herein may be combined with each other without departing from the scope of protection of the present invention.

[0041] The electromagnetic fuel injector 1 described above has many advantages.

[0042] Firstly, the electromagnetic fuel injector 1 described above has a lower noise level and less deterioration (wear) due to the fact that the impact of the armature 19 against the main armature 14 (at the end of the opening step) and the impact of the shutter 9 against the valve seat of the injector 7 (at the end of the closing step) occurs at a significantly reduced impact speed. Furthermore, in this way the bounce phenomenon, which introduces a certain element of randomness into the amount of fuel injected, is reduced.

[0043] Furthermore, the above described electromagnetic fuel injector 1 is simple and inexpensive to manufacture as it has few easily manufacturable design differences compared to similar known electromagnetic injectors. [Explanation of symbols]

[0044] 1 Fuel Injector 2 Longitudinal axis 3. Injection nozzle 4 Support 5. Supply Channels 6 Electromagnetic Actuator 7 Injection valve 8 Plunger 9. Shutter 10 Closing spring 11 Main electromagnet 12 Secondary electromagnet 13 Main coil 14 Main Armature 15 Central Hall 16 Secondary coil 17 Secondary Armature 18 Central Hall 19 Armature 20 Control Unit 21 Controller 22 Controller

Claims

1. An electromagnetic fuel injector (1), comprising: A tubular support (4), a spray nozzle (3) arranged at the end of said support (4); an injection valve (7) coupled to the injection nozzle (3); a plunger (8) movable between a closed position and an open position of the injector (7) to adjust the fuel flow through the injection nozzle (3); an electromagnetic actuator (6), the electromagnetic actuator (6) comprising a main electromagnet (11) configured to apply a force to the plunger (8) when activated, urging the plunger (8) towards the open position of the injector (7), and a secondary electromagnet (12) configured to apply a force to the plunger (8) when activated, urging the plunger (8) towards the closed position of the injector (7); a closing spring (10) configured to urge the plunger (8) towards the closed position of the injection valve (7); a control unit (20) configured to activate the main electromagnet (11) such that the main electromagnet (11) generates a magnetic force that overcomes the elastic force of the closing spring (10) to move the plunger (8) towards the open position to open the injection valve (7); wherein the control unit (20) is configured to also activate the secondary electromagnet (12) during opening of the injection valve (7) and when the plunger (8) is close to the open position, such that the secondary electromagnet (12) generates a magnetic force that slows down a movement of the plunger (8) towards the open position.

2. 2. The electromagnetic injector (1) according to claim 1, wherein the electromagnetic actuator (6) comprises a single armature (19), which is movable, integrated into the plunger (8) and shared by both electromagnets (11, 12) since it is subjected to the magnetic forces generated by both electromagnets (11, 12).

3. The main electromagnet (11) comprises a main armature (14) integrated in the support (4) and a main coil (13) arranged in the area of ​​the main armature (14), The secondary electromagnet (12) comprises a secondary armature (17) integrated in the support (4) and a secondary coil (16) arranged in the area of ​​the secondary armature (17), and 3. The electromagnetic injector (1) according to claim 2, wherein the armature (19) is disposed between the main armature (14) and the secondary armature (17).

4. the closed position of the injection valve (7) is determined by the contact of a shutter (9) of the plunger (8) against a valve seat of the injection valve (7); and 4. The electromagnetic injector (1) according to claim 3, wherein the open position of the injection valve (7) is determined by contact of the moveable armature (19) against the main armature (14).

5. the two coils (13, 16) of the two electromagnets (11, 12) are not connected in series or in parallel with respect to each other; and 4. The electromagnetic injector (1) according to claim 3, wherein the control unit (20) is configured to power the two coils (13, 16) of the two electromagnets (11, 12) independently of each other.

6. The control unit (20) controls the injection valve (7) to open activating the main electromagnet (11) such that the main electromagnet (11) generates a magnetic force that attracts the armature (19) towards the main armature (14) and overcomes the elastic force of the closing spring (10), thus moving the armature (19) towards the open position; and 4. The electromagnetic injector (1) according to claim 3, further configured to activate the secondary electromagnet (12) when the armature (19) is close to the open position, such that the secondary electromagnet (12) generates a magnetic force attracting the armature (19) towards the secondary armature (17), thereby slowing down the movement of the armature (19) towards the open position.

7. 7. The electromagnetic injector (1) of claim 6, wherein the control unit (20) is configured to deactivate the secondary electromagnet (12) before the armature (19) reaches the open position.

8. The control unit (20) controls the injection valve (7) to close. turning off the main electromagnet (11) so that the armature (19) is pushed towards the closed position by the elastic force generated by the closing spring (10); and 7. The electromagnetic injector (1) according to claim 6, configured to activate the main electromagnet (11) when the armature (19) is close to the closed position such that the main electromagnet (11) generates a magnetic force attracting the armature (19) towards the main armature (14), thereby slowing down the movement of the armature (19) towards the closed position.

9. 9. The electromagnetic injector (1) according to claim 8, wherein the control unit (20) is configured to deactivate the main electromagnet (11) before the armature (19) reaches the closed position.

10. 10. The electromagnetic injector (1) according to any one of claims 1 to 9, wherein the control unit (20) is configured to deactivate the secondary electromagnet (12) before the plunger (8) reaches the open position.

11. The control unit (20) controls the injection valve (7) to close. turning off the main electromagnet (11) so that the plunger (8) is pushed towards the closed position by the elastic force generated by the closing spring (10); and 10. The electromagnetic injector (1) according to claim 1 , configured to activate the main electromagnet (11) when the plunger (8) is close to the closed position, such that the main electromagnet (11) slows down the movement of the plunger (8) towards the closed position.

12. 12. The electromagnetic injector (1) according to claim 11, wherein the control unit (20) is configured to deactivate the main electromagnet (11) before the plunger (8) reaches the closed position.

13. A method for controlling an electromagnetic fuel injector (1), comprising: A tubular support (4), a spray nozzle (3) arranged at the end of said support (4); an injection valve (7) coupled to the injection nozzle (3); a plunger (8) movable between a closed position and an open position of the injector (7) to adjust the fuel flow through the injection nozzle (3); an electromagnetic actuator (6), the electromagnetic actuator (6) comprising a main electromagnet (11) configured to apply a force to the plunger (8) when activated, urging the plunger (8) towards the open position of the injector (7), and a secondary electromagnet (12) configured to apply a force to the plunger (8) when activated, urging the plunger (8) towards the closed position of the injector (7); a closing spring (10) configured to urge the plunger (8) towards the closed position of the injection valve (7); The control method includes the step of activating the main electromagnet (11) so that the main electromagnet (11) generates a magnetic force that overcomes the elastic force of the closing spring (10) and moves the plunger (8) towards the open position to open the injection valve (7).

11. A control method, characterized in that the control method also includes the step of activating the secondary electromagnet (12) during opening of the injection valve (7) and when the plunger (8) is close to the open position, such that the secondary electromagnet (12) generates a magnetic force that slows down the movement of the plunger (8) towards the open position.

14. The control method includes: turning off the main electromagnet (11) so that the plunger (8) is pushed towards the closed position by the elastic force generated by the spring (10); and activating the main electromagnet (11) when the armature (19) is close to the closed position such that the main electromagnet (11) slows down the movement of the plunger (8) towards the closed position.

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