EP3156638B1

EP3156638B1 - Fuel injector

Info

Publication number: EP3156638B1
Application number: EP15189838.4A
Authority: EP
Inventors: Filippo Falaschi; Ivano Izzo; Luigi Marchi
Original assignee: Vitesco Technologies GmbH
Current assignee: Vitesco Technologies GmbH
Priority date: 2015-10-14
Filing date: 2015-10-14
Publication date: 2020-03-18
Anticipated expiration: 2035-10-14
Also published as: EP3156638A1

Description

The invention refers to a fuel injector.
WO 2015/049195 A1 discloses a valve assembly for an injection valve for injecting fuel into an internal combustion engine, which valve assembly contains a valve needle, a valve spring and an electromagnetic actuator with a coil, a pole piece and a movable armature. The armature is set up to be moved in the axial direction towards the pole piece out of a first position by a predefined idle travel into a second position and from that by a predefined actuating travel into a third position, wherein the armature acts only between the second and the third position on the valve needle to move the valve needle to a fourth position. On a side which faces the pole piece a spring element bears against the armature, in order to press the armature in the direction of the first position.
US 2009/288640 A1 discloses a fuel injector valve comprising a fuel inlet, wherein a fuel line connects the fuel inlet to an injection nozzle. The fuel injector comprises further an armature which is movable arranged, a needle which is movable arranged along an axis controlling an opening of the valve. The injector comprises a stopper which is fixed to the needle. The injector comprises a valve-closing spring which is arranged between the armature and a member of the fuel injector and which is biasing the armature away from the stop element. This valve-closing spring is arranged in a receptacle of the armature. The recess is hydraulically connected to a further recess of the fuel injector by means of a channel comprised by the armature.
Also JP 2011 069331 A , EP 2 871 353 A1 and DE 10 2013 010 271 Al disclose various embodiments of injection valves for injection fuel.
It is an object of the proposed fuel injector to improve the technical function of the fuel injector especially to reduce hydraulic dampening effects during the function of the fuel injector. The object of the invention is achieved by the fuel injector according to claim 1. Further embodiments of the fuel injector are disclosed in the dependent claims.
A fuel injector is disclosed. The fuel injector is in particular a fuel injector for a fuel injection system of an internal combustion engine. The injector comprises an inlet for fuel and a fuel line which connects the inlet to a valve. It further comprises an armature which is movably arranged between a first and a third position. Preferably, the injector comprises a valve body which defines at least a section of the fuel line. The armature is preferably positioned in a recess of the valve body. The first and third positions are in particular axial positions of the armature with respect to a longitudinal axis of the valve body.
Further, the fuel injector comprises a valve needle which is movably arranged along an axis, in particular the longitudinal axis of the valve body. The valve needle is operable to control an opening of the valve. In particular the valve comprises a seat and a sealing element. The sealing element is in particular comprised by the valve needle; for example it is represented by a tip of the valve needle. The valve needle is in particular operable to prevent fuel flow through an injection opening of the valve when it is in a closing position. In the closing position, the sealing element may expediently be in sealing mechanical contact with the seat. The valve needle is in particular axially displaceable away from the closing position for unsealing the valve.
In addition, the fuel injector comprises a retainer element which is fixed to or in one piece with the valve needle. In particular, the retainer element is positioned arranged adjacent to an axial end region of the valve needle which is remote from the sealing element.
A first spring element is arranged between the armature and a member of the fuel injector. In particular, the first spring element is axially compressed by the armature and the member so that it is preloaded. The first spring element is operable to bias the armature away from the retainer element, i.e. in particular in axial direction towards the first position.
The fuel injector further comprises an actuator for moving the armature from the first position to the third position, via a second position. In the first position, the armature is at a first distance to the retainer element. In the second position, the armature engages the retainer element to displace the valve needle away from the closing position. In particular, the armature acts only between the second and the third position on the valve needle to move the valve needle for unsealing the valve.
The first spring element is arranged in a spring receptacle, at least in places. The spring receptacle comprises a first recess of the armature which is hydraulically connected to a further recess of the fuel injector by means of a channel which is comprised by the armature. Additionally, the spring receptacle comprises a second recess of the member which is hydraulically connected to the further recess by means of a channel which is comprised by the member. The further recess is in particular the recess of the valve body outside of the armature or the member, respectively.
In an expedient embodiment, the first spring element projects from the first recess on one axial side of the armature and the channel opens out into the further recess at the opposite axial side of the armature or at a circumferential surface of the armature. In another expedient embodiment, the first spring element projects from the second recess on one axial side of the member and the channel opens out into the further recess at the opposite axial side of the member or at a circumferential surface of the member.
The proposed fuel injector provides the advantage that hydraulic dampening effects during the opening or closing the fuel injector are reduced. For example hydraulic dampening is reduced or eliminated during movement of the valve needle and/or the armature. This technical effect is attained by the channel(s) of the armature and/or the member that is/are connected with the first or second recess, respectively, and the further recess of the fuel injector.
The invention makes use of the idea that the channel reduces pressure changes that may be generated in the spring receptacle by moving the armature and/or the valve needle. For example, during the movement of the armature towards the retainer element, fuel may be pressed towards the first and/or second recesses. Since the recesses are arranged in the fuel line and already filled up with fuel, this may lead to an increase of the fuel pressure in the recess(es) impeding further movement of the armature and/or the valve needle. By means of the channel(s) of the fuel injector according to the present disclosure, a particularly small magnitude or such hydraulic dampening effect is achievable. This is in particular due to the fact that the fuel can flow out of the recess(es) through the respective channel(s), thereby in particular avoiding or largely reducing buildup of elevated fuel pressure in the recess(es) during movement of the armature and the needle, respectively. Since the hydraulic dampening that is caused by the armature is at least partially decreased, the movement of the armature is accelerated. Furthermore, because of the channel also a displacement of the armature away from the third position to the second or first position is possible with less or no hydraulic dampening forces because fuel can flow, for example through the channel of the armature into the first recess, preventing or largely reducing a pressure difference that may be generated between the recess and the further recess of the fuel injector.
In a further embodiment, the first recess is embodied as a circular ring recess that is arranged in the armature and/or the second recess is embodied as a circular ring recess that is arranged in the member of the fuel injector. The circular ring recess may be arranged axially symmetric with regard to a middle axis of the valve needle - which middle axis is in particular represented by the longitudinal axis of the valve body. A circular ring recess provides the advantage that the recess provides sufficient space for a circular spring element. Furthermore, the spring element can be axially symmetric arranged with regard to the middle axis of the valve needle. Therefore a symmetric spring force can be applied to the valve needle.
According to the invention, the above-mentioned member of the fuel injector is represented by the retainer element. The second recess is comprised by the retainer element. Furthermore, the first spring is arranged between - and in particular seated against and preloaded by - the retainer element and the armature.
In an alternative unclaimed embodiment, the above-mentioned member of the fuel injector is a stopping element. The stopping element may be a part of a housing of the fuel injector that is provided for stopping the armature at the third position. The housing in particular comprises or consists of the valve body. The armature in particular abuts the stopping element in the third position so that the stopping element blocks further displacement of the armature away from the first position. In this embodiment the first spring is disposed between the stopping element and the armature. Also the first recess may be comprised by the stopping element. The stopping element may be made of magnetic material and operable to guide a magnetic field of a solenoid. The stopping element may be a pole piece - i.e. in particular a stationary core - of the actuator. In one development, is press-fitted into the valve body. The solenoid is particular comprised by the actuator for axially displacing the armature.
In a further embodiment, the first recess is a cylindrical recess of the armature. The recess is arranged in line - i.e. in particular coaxial - with the bore for the valve needle. In other words, the armature has a hole - i.e. the bore - through which the valve needle extends. The hole may open into a bottom surface of the cylindrical recess. The valve needle in particular extends also through the first recess. The recess extends circumferentially around the valve needle.
The first spring element extends circumferentially around the valve needle in the first recess. It may be seated against the bottom surface of the first recess. Because of the symmetric shape of the recess and the spring element with respect to the middle axis of the valve needle the applied forces may be symmetrically applied.
According to the invention, the second recess is a cylindrical recess in the retainer element. The valve needle extends through the second recess and is radially spaced from a lateral surface of the second recess. In other words, the second recess extends circumferentially around the valve needle. In addition, the spring element extends circumferentially around the valve needle in the second recess.
In a further embodiment, the spring receptacle comprises both, the first recess and the second recess. In one development, the first recess and the second recess have the same shape, especially the same circular ring shape or cylindrical shape.
Advantageous embodiments and developments of the fuel injector will become apparent from the exemplary embodiments described below in association with the figures.
In the figures:

Fig. 1: depicts a schematic longitudinal section view of a fuel injector.
Fig. 2: depicts an enlarged longitudinal section view of a detail of one embodiment of a fuel injector.
Fig. 3: depicts an enlarged longitudinal section view of a detail of a second unclaimed embodiment of a fuel injector.
Fig. 4: depicts an enlarged longitudinal section view of a detail of a third unclaimed embodiment of a fuel injector.
FIG. 5: depicts a schematic view on an armature according to a fourth embodiment.
FIG. 6: depicts a schematic view on the armature of the first and second embodiments.
FIG. 7: depicts a schematic top view on the retainer element of the second embodiment.
FIG. 8: depicts a schematic top view on the stopping element of the third embodiment.

In the exemplary embodiments and figures, identical, similar or similarly acting constituent parts are provided with the same reference symbols. In some figures, individual reference symbols may be omitted to improve the clarity of the figures. The elements illustrated in the figures and their size relationships among one another should not be regarded as true to scale. Rather, individual elements may be represented with an exaggerated size for the sake of better representability and/or for the sake of better understanding.
The fuel injector 1 comprises a fuel inlet 2 that can be connected to a fuel line. The fuel injector 1 is for example executed in the shape of an injector for fuel injection systems for spark ignition internal combustion engines. The fuel injector 1 is in this example embodied for a direct injection of fuel into a combustion chamber of an internal combustion engine. The fuel injector can also be embodied for other applications.
The fuel injector 1 comprises a fuel line 3 that is guided from the fuel inlet 2 through the fuel injector 1 to a fuel chamber 25 at a valve 4. An opening of the valve 4 is controlled by a valve needle 5. The valve 4 comprises a valve closure member 6 - i.e. a sealing element - that is arranged at a front tip of the valve needle 5. The valve closure member 6 cooperates with a valve seat 7. The valve seat 7 is configured at a fuel outlet end of a valve body 8. The valve body 8 has a hollow and generally cylindrical shape. An upper section of the valve body is surrounded by an actuator housing 9 of the fuel injector 1. The actuator housing 9 comprises a magnetic yoke 10. Depending on the used embodiment a laser welding connection may be used to connect the valve body 8 with the yoke 10.
The fuel injector 1 comprises an electromagnetic actuator which has a solenoid 11 that is arranged in the housing 9. An excitation of the solenoid 11 by an electrical excitation current is supplied via an electrical connecting line.
Furthermore an armature 12 is disposed in the valve body 8. The armature 12 comprises a hole 13 through which the valve needle 5 projects. An outer face of the armature 12 may be guided by an inner face of the valve body 8. In a further embodiment the armature may be guided by the valve needle by means of the hole 13 being in sliding mechanical contact with the valve needle 5. The armature 12 is axially displaceable in reciprocating fashion relative to the valve body 8 between a first position and a third position with respect to the longitudinal axis 14.
The armature 12 is movably guided in the valve body 8 parallel to the longitudinal middle axis 14 of the valve needle 5 which coincides with the longitudinal axis of the valve body 8. The armature 12 is axially guided by an outer surface 15 and a corresponding inner surface 16 of the valve body 8. For example the outer surface 15 of the armature 12 may have a circular cylindrical shape and also the inner surface 16 of the valve seat support 8 may have a circular cylindrical shape.
The valve needle 5 comprises a retainer element 17 that is connected at a first end 18 of the valve needle 5 opposite to a second end 19 of the valve needle 5. The second end 19 is connected with the valve closure member 6. Furthermore the valve needle 5 comprises a disc element 20 that is positioned at the second end 19 of the valve needle 5. Between the retainer element 17 and the disc element 20, the armature 12 is arranged so that it has an axial play with respect to the valve needle 5 that is limited by the retainer element 17 and the disc element 20 in opposite axial directions. The retainer element 17 has the shape of a ring. The disc element 20 may have the shape of a circular plate.
The valve needle 5 is movably arranged in the fuel injector 1 along the middle axis 14; i.e. it is axially displaceable relative to the valve body 8 in the fuel chamber 25. The valve needle is biased in direction to the valve seat 7 by preloaded a second spring 21. The second spring 21 is in one embodiment a spring element, in particular a coil spring.
Furthermore the fuel injector 1 comprises a stopping member 22. The stopping member 22 may have a hollow cylindrical basic shape and extend circumferentially around the retainer element 17. The stopping member 22 has the shape of a sleeve with a circular stopping face 23 that faces a further stopping face 24 of the armature 12. The stopping member 22 may be embodied as a pole piece of the actuator, for example made of magnetic material for guiding the magnetic field of the solenoid 11 to the armature 12.
The fuel injector 1 functions as follows: Fuel is guided via the fuel inlet by the fuel inlet 2 and the fuel line 3 to the fuel chamber 25 that surrounds the second end 19 of the valve needle 5. The fuel line 3 can be guided through specific bores in the valve body 8, bores in the valve needle 5 and/or fuel bores 27 in the armature 12. The fuel chamber 25 is arranged between the second end 19 of the valve needle 5 and the valve seat 7 of the valve body 8. When the valve needle 5 is in a closing position, the fuel chamber 25 is closed by the valve closure member 6, being in sealing contact with the valve seat 7. The valve needle 5 is biased in direction to the valve seat 7 by the second spring 21, pressing the valve closure member 6 against the valve seat 7. In this closed configuration, no fuel is injected by the valve 4. The armature 12 is pressed against a second stopping face 26 of the disc element 20 by the bias of a first spring element 24 (not shown in Fig. 1). This position is the first position of the armature 12. In the first position the armature is axially spaced apart from the retainer element 17.
Fuel can be injected by the fuel injector 1 by energizing the solenoid 11 for opening the valve 4. The energized solenoid 11 generates a magnetic field that attracts the armature 12 in direction to the stopping element 22 until it engages in form-fit connection with the stopping element 22. This position - i.e. the armature 12 being in form-fit connection with the stopping element 22 so that further axial displacement away from the first position is blocked - corresponds to the third position of the armature 12.
During the movement of the armature 12 from the first to the third position, the armature 12 passes a second position where it comes in contact with the retainer element 17. The further stopping face 24 of the armature 12 abuts a lower surface 28 of the retainer element 17.
The lower surface 28 of the retainer element 17 is in the closed configuration of the fuel injector 1 closer to the further stopping face 24 of the armature 12 than the stopping face 23 of the stopping element 22. In other words, the axial gap between the retainer element 17 and the armature 12 is smaller than the axial gap between the armature 12 and the stopping element 22 when the fuel injector 1 is in the closed configuration. Therefore, the armature 12 takes the valve needle 5 with it when it travels from the second position further to the third position. Thus, the moving armature 12 pushes the retainer element 17 away from the valve 4. The retainer element 17 is rigidly fixed to the valve needle 5 and therefore also the valve needle 5 is pushed away from the valve 4. As a result also the closure member 6 disengages from the valve seat 7. As a result an orifice 29 of the valve seat 7 is opened and fuel of the fuel chamber 25 can be injected via the orifice 29. The armature 12 moves away from the valve 4 until the further stopping face 24 of the armature 12 abuts the stopping face 23 of the stopping element 22 at the third position of the armature 12. This corresponds to the fully open configuration of the fuel injector 1.
The injection can be stopped by stopping the current through the solenoid 11. As a result the magnetic field decreases and the magnetic force that pulls the armature 12 in the direction to the stopping element 22 also decreases and stops. Since the magnetic force gets smaller than the preload force of the second spring 21 that still biases the valve needle 5 in direction to the valve seat 7, the valve needle 5 is pushed with the closure member 6 towards and into contact with the valve seat 7, thereby closing the orifice 29. The second spring 21 is a resetting spring that is provided to hold the valve needle 5 in a sealing position closing the orifice 29.
In the first position of the armature 12, a first gap 30 between the lower surface 28 of the retainer element 17 and the further stopping face 24 of the armature 12 is smaller than a second gap 31 between the further stopping face 24 of the armature 12 and the stopping face 23 of the stopping member 22. However, these details are not shown in Fig. 1.
The armature 12 is a moving member that is movably arranged parallel to the middle axis 14 of the needle in the fuel injector 1 between the first and third positions via the second position. The solenoid 11 is comprised by an actuator that is provided for moving the armature 12 from the first over the second to the third position. In the first position, the armature 12 is at a first distance to the retainer element 17. In the second position, the armature 12 abuts the retainer element 17. During the further movement, the armature 12 moves the retainer element 17 and the valve needle 5 until the armature 12 abuts the stopping element 22 in the third position.
The proposed fuel injector makes use of the idea to reduce hydraulic effects on the armature 12 that are caused by the movement of the armature 12. Fig. 1 only depicts a principle embodiment and function of a fuel injector. The following Figs. 2 to 4 show different embodiments of fuel injectors with less hydraulic forces caused by the moving of the armature 12 in detail.
Fig. 2 depicts an enlarged partial sectional view of a first embodiment of the fuel injector 1 that is basically embodied as shown in FIG.1. For the sake of simplicity, only the right half of a longitudinal section of a detail of the fuel injector 1 is depicted. The fuel injector is basically axially symmetric to the longitudinal axis 14 of the valve needle 5. The armature 12 is depicted in the first position which means that the valve 4 is closed.
In the first position the first gap 30 is arranged between the further stopping face 24 of the armature 12 and the lower surface 28 of the retainer element 17. Furthermore the second gap 31 is arranged between the further stopping face 24 of the armature 12 and the stopping face 23 of the stopping member 22. The first gap 30 is smaller than the second gap 31. The fuel injector 1 is basically rotationally symmetric to the longitudinal axis 14.
Fig. 2 depicts a partial view of a spring receptacle 35 comprising a first recess 32 and a second recess 33. The first recess 32 is disposed at the further stopping face 24 of the armature 12. The second recess 33 is disposed at the lower surface 28 of the retainer element 17. Thus, the spring receptacle 35 is arranged partially in the retainer element 17 and partially in the armature 12. In other embodiments, there may only be the first recess 32 or the second recess 38 constituting the spring receptacle 35. A first spring element 34 is arranged in the spring receptacle 35. The first spring element 34 is preloaded between the retainer element 17 and the armature 12 so that it biases the armature 12 with an axial force away from the retainer element 17 in direction to the disc element 20.
The first spring element 34 is arranged in the first recess 32 and in the second recess 33. In the shown embodiment, the first and the second recess 32, 33 are arranged coaxial to the longitudinal axis 14. The first and the second recess 32, 33 represent a spring receptacle 35 for receiving the first spring element 34.
The force of the first spring element 34 is lower than the force of the second spring element 21. The force of the first spring element 34 may be in an area between 2 N and 15 N. There may be a difference of about 5 to 50 N between the force of the second spring element 21 and the force of the first spring element 34 in one embodiment.
When the solenoid 11 is excited by an electrical excitation current, the armature 12 is pulled in direction to the stopping element 22. In the second position, the armature 12 abuts the lower surface 28 of the retainer element 17 for moving the retainer element 17 and the valve needle 5 away from the valve seat 7. In the third position, the armature 12 abuts the stopping face 23 of the stopping element 22. The stopping element 22, the armature 12, the retainer element 17 and the disc element 20 have rotationally symmetric basic shapes with regard to the longitudinal axis 14.
During the movement of the armature 12 from the first position to the third position the volume gap between the first recess 32 and the second recess 33 is decreased. Since the first and second recesses 23, 33 as well as the gap between them are filled with fuel, the decreasing of the gap may press the fuel into the first and second recesses 32, 33. This would cause a hydraulic dampening force against the movement of the armature 12. To reduce this dampening force, at least one channel 36, 40 is provided that connects the spring receptacle 35 with a further recess 37 of the fuel injector 1 through the armature 12 and/or through the retainer element 17. The further recess 37 may be embodied as an open or closed chamber of the fuel injector. In the shown embodiment, the channel 36 is guided from the first recess 32 through the armature 12 to a region of the further recess 37 of the fuel injector 1 adjacent to the disc element 20. The first spring element 34 projects from the armature 12 at one axial end of the armature 12 - specifically, the first recess 32 opens out towards the retainer element 17 at that axial end and the first spring element 34 projects from the first recess 32 to the retainer element 17. The channel 36 opens into the further recess 37 at the opposite axial end of the armature 12. Fuel can escape through the channel 36 should into the further recess 37 of the fuel injector 1 during a movement of the armature 12. There may also be more than one channel 36 that connect the spring receptacle 35 with the further recess 37 of the fuel injector.
Also when the armature 12 is moved back from the third position back to the second or first position, then fuel can flow through the channel 36 into the first recess 32 and into the gap between the armature 12 and the retainer element 17. With advantage, hydraulic damping of the movement of the armature from the third to the first position due to the increasing of the volume of the gap is particularly small in this way.
The first recess 32 and the second recess 33 may have the same or different shapes. For example the first recess and the second recess 32, 33 may be embodied as circular ring recesses that are arranged symmetrical to the middle axis 14. In the present embodiment, the first and the second recesses 32,33 have a cylindrical shape and are arranged symmetrical to the longitudinal axis 14. The first spring element 34 may be embodied as coil spring that is arranged axial symmetric to the longitudinal axis 14.
In the shown embodiment, the first recess 32 and the second recess 33 are adjacent to the valve needle 5 so that the valve needle 5 extends through the recesses 32, 33. In other embodiments, the first recess 32 and the second recess 38 may also be arranged within the armature 12 or the retainer element 17 with a distance to the valve needle 5.
While a channel 36 in the armature 12 is preferred, it is also conceivable that a further channel 40 is provided additionally or alternatively in the retainer element 17. In the present embodiment, the channel 40 of the retainer element 17 extends from a bottom surface of the second recess 33 - the second recess 33 opening out towards the armature 12 and the first spring element 34 projecting from the second recess 33 to the armature 12 - to an axial end region of the retainer element 17 remote from the armature 12.
Fig. 3 depicts a partial view of a second embodiment of a fuel injector 1 that is basically constructed as the fuel injector of Figures 1 and 2 However, in the present embodiment the spring receptacle 35 is only represented by the first recess 32 in the armature 12 and does not comprise a second recess 33 in the retainer element 17. The first spring element 34 is received in the spring receptacle 35.
The first spring element 34 is disposed between the armature 12 and the retainer element 17. The channel 36 connects the spring receptacle 35 with an area of the further recess 37 adjacent to the disc element 20. In other embodiments, the first recess 32 may also be arranged within the armature 12 a distance to the valve needle 5.
FIG.4 depicts a partial view of a third embodiment of a fuel injector 1 that is basically constructed as the fuel injectors of the first and second embodiments.
In contrast to the first and second embodiments, the armature 12 comprises the first recess 32 at an outer rim surrounding the further stopping face 24. In other words, the recess 32 is formed in an outer circumferential surface of the armature 12.
Additionally in contrast to the first and second embodiment, the second recess 33 is not comprised by the retainer element 17 but by the stopping element 22. The second recess 33 circumferentially surrounds the stopping face 23. The first spring element 34 is arranged between and preloaded by the stopping member 22 and the armature 12 in the present embodiment. The first spring element 34 is arranged in the first recess 32 and in the second recess 33. In the shown embodiment, the first and the second recess 32, 33 are arranged coaxial and overlapping in top view of the longitudinal axis 14. The first and the second recess 32, 33 represent the spring receptacle 35 for receiving the first spring element 34.
Similar to the first and second embodiments, the channel 36 connects the first recess 32 at the axial side of the armature 12 which faces towards the stopping element 22 hydraulically to a region of the further recess 37 on the opposite axial side of the armature. In the shown embodiment the channel 36 is guided from the first recess 32 through the armature 12 to a region of the further recess 37 of the fuel injector 1 adjacent to the disc element 20.
In the present embodiment, the further channel 40 is comprised by the stopping element 22, connecting the second recess 33 with a region of the further recess 37 of the fuel injector 1 adjacent to an axial end of the stopping element 22 remote from the armature.
In the shown embodiment, the recesses 32, 33 are arranged at radial outer surfaces of the armature 12 and the stopping member 22. Depending on the used embodiment, the first and the second recesses 32, 33 can also be arranged in other radial positions for example in a radial middle position of the stopping member 22 with regard to the longitudinal axis 14.
Fig. 4 depicts the closed configuration of the fuel injector, wherein the armature 12 is in the first position lying on the disc element 20. The channel 36 provided in the armature 12 connects the first recess 32 with a region of the further recess 37 beside the disc element 20. Additionally the further channel 40 in the stopping element 22 connects the second recess 33 with a region 39 of the further recess 37 that is arranged radially between the valve body 8 and the stopping member 22. Also in this embodiment the channel 36 and the further channel 40 reduce the generation of hydraulic dampening effects during the movement of the armature 12.
Fig. 5 depicts a schematic view on the further stopping face 24 of the armature 12, wherein the first recess 32 is circular and has a distance to the hole 13 through which the valve needle 5 extends.
Fig. 6 depicts a schematic view on the further stopping face 24 of the armature 12 of the first and second embodiment, wherein the first recess 32 is cylindrical and the hole 13 opens into a bottom surface of the first recess 32.
Fig. 7 depicts a schematic view on the lower surface 28 of the retainer element 17 according to the first embodiment, wherein the second recess 33 is cylindrical and the valve needle 5 extends through the second recess 32. The valve needle 5 is radially spaced from a lateral surface of the second recess 33.
FIG.8 depicts a schematic view on the stopping face 23 of the stopping element 22 according to the third embodiment with a circular second recess 33 at an outer rim area.
For all shown embodiments the first and the second recess 32, 33 may have different shapes. Depending on the used embodiment, the first recess, the second recess and the further second recess 32, 33, 38 are axial symmetric with regard to the longitudinal axis 14 that is a middle axis of the fuel injector 1. Depending on the used embodiments, the axial lengths of the first, second and/or further second recesses 32, 33, 38 are similar or equal or different. Also the width of the first, second and further second recesses 32, 33, 38 may be different, although equal widths are preferred in particular in case of a first spring element 34 having the same lateral dimensions at both axial ends.
For all shown embodiments, the retainer element 17 may be embodied as a ring that is fixed to the valve needle 5, for example by a welding connection and/or a crimped connection. In a further embodiment the retainer element may be embodied in one part and in one material with the valve needle.
For all shown embodiments, the disc element 20 may be embodied as a ring plate that is fixed to the valve needle 5 for example by a welding connection. The ring plate may have an L-shaped cross-section. In a further embodiment the disc element may be embodied in one part and in one material with the valve needle.
Furthermore there might be an embodiment with a combination of FIG.2 and FIG.4 or with FIG.3 and FIG.4 with two spring elements 34 and with two spring receptacles 35. Also in this embodiment each or only one of the spring receptacles 35 may be connected by a channel 36 and/or a further channel 40 that connect the spring receptacles 35 with the further recess 37.

Claims

A fuel injector (1) for a fuel injection system of an internal combustion engine, comprising:
an inlet (2) for fuel;

a fuel line (3) connecting the inlet (2) to a valve (4);

an armature (12) being movably arranged between a first and a third position;

a valve needle (5) being movably arranged along an axis (14) controlling an opening of the valve (4);

a retainer element (17) being fixed to or in one piece with the valve needle (5);

a first spring element (34) being arranged between the armature (12) and a member (17, 22) of the fuel injector (1)) and biasing the armature (12) away from the retainer element (17) ;

the first spring element (34) being arranged in a spring receptacle (35);an actuator for moving the armature (12) from the first position to the third position via a second position,

wherein
- in the first position, the armature (12) is at a first distance to the retainer element (17),

- in the second position, the armature (12) engages the retainer element (17) to displace the valve needle (5) away from a closing position,

- the spring receptacle (35) comprises a first recess (32) of the armature (12) which is hydraulically connected to a further recess (37) of the fuel injector (1) by means of a channel (36) comprised by the armature (12)

wherein

the spring receptacle (35) comprises a second recess (33) of the member (17, 22) which is hydraulically connected to the further recess (37) by means of a further channel (40) comprised by the member (17, 22),

wherein the first spring element (34) is arranged in the first recess (32) and the second recess (33),

wherein the member of the fuel injector is the retainer element (17) and

wherein the second recess (33) is embodied as a cylindrical recess in the retainer element (17), wherein the second recess (33) extends circumferentially around the valve needle (5), and wherein the first spring element (34) extends circumferentially around the valve needle (5) in the second recess (33) and

wherein a disc element (20) is connected with the valve needle (5), wherein the armature (12) is arranged between the retainer element (17) and the disc element (20), wherein the armature (12) is biased towards the disc element (20) by the first spring element (34).
Fuel injector of the preceding claim, wherein the first spring element (34) projects from the recess on one axial side and the channel (36) opens out into the further recess (37) at the opposite axial side.
Fuel injector of any one of the preceding claims, wherein the first recess (32) and/or the second recess (33) is embodied as a circular ring recess.
Fuel injector of any one of the preceding claims, wherein the member of the fuel injector is a stopping element (22) of the fuel injector which the armature (12) abuts in the third position so that the stopping element (22) blocks further displacement of the armature (12) away from the first position for of the armature (12),
Fuel injector of the preceding claim, wherein the stopping element (22) is a pole piece of the actuator which is made of magnetic material and operable to guide a magnetic field that is generated by a solenoid (11) of the actuator.
Fuel injector of any one of the preceding claims, wherein the first recess (32) is a cylindrical recess, wherein the armature (12) has a hole (13), wherein the valve needle (5) extends through the hole (13), wherein the recess is arranged coaxial with the hole (13) for the valve needle (5), wherein the recess (32) extends circumferentially around the valve needle (5), and wherein the first spring element (34) extends circumferentially around the valve needle (5) in the first recess (32).
Fuel injector of any one of the preceding claims, wherein the spring receptacle (35) comprises the first recess (32), and the second recess (33), and wherein preferably the first recess (32) and the second recess (33) have the same shape.
Fuel injector of any one of the preceding claims, further comprising a second spring element (21) which is operable to bias the valve needle (5) towards a seat (7) of the valve (4).
Fuel injector of any one of the preceding claims, wherein the first spring element (34) is a spiral spring or a leaf spring.
Fuel injector of any one of the preceding claims, wherein the armature (12) has a hole (13), wherein the valve needle (5) projects through the hole (13).