Injector for injecting fuel

Abstract

The present invention relates to an injector for injecting fuel, preferably for blowing-in a gaseous fuel, in particular hydrogen, comprising an injector housing for receiving and arranging injector components, an armature element which is arranged in the injector housing so as to be movable along an axial direction (that is to say the injector longitudinal direction) of the injector and is designed to close or to open a throttle by way of an axial movement along the injector housing in order to allow fuel to flow through this throttle, a solenoid valve which is designed to move the armature element from a closing state to an opening state of the throttle and vice versa, an armature mating piece which is arranged on that side of the armature element opposite the throttle and, in a state of the armature element closing the throttle, defines a gap from the armature element, the gap running in the axial direction and corresponding to a maximum travel of the armature element during a lifting-off process from the throttle, and a non-magnetic or only weakly magnetizable bypass element for targeted control of magnetic field lines, the bypass element being arranged in or on the injector housing level with the gap, as seen in the axial direction. The invention is characterized by a guide element which is attached to an outer circumference of the armature element or is arranged there in order to allow movement of the armature element, without wear as far as possible, in the axial direction in relation to the injector housing during opening and closing of the throttle, the guide element being at a distance from the bypass element in the axial direction given minimum travel of the armature element.

Description

[0001] 00624-24 La / Se Liebherr-Components Deggendorf GmbH DE - Deggendorf ^ ...For vehicles that operate with combustion, these goals can only be achieved with the use of climate-neutral, renewably produced fuels that cause no emissions along the entire value chain (so-called "zero-emissions" fuels). With current conventional gasoline, diesel, and gas engines, the requirements for emission-free combustion are not achievable – even with the use of so-called e-fuels, e.g., a synthetically produced OME fuel, the production of which requires only renewable energy – because the emissions of harmful exhaust gases such as nitrogen oxides (NOx), unburned hydrocarbons (UHC), and soot cannot be completely reduced with current technologies. In principle, battery-powered drives comply with the Zero Emissions Directive during operation and are gaining ground, especially in the passenger car sector. However, if the entire value chain is considered,However, the production of (lithium) batteries is very costly in terms of energy and problematic from an environmental perspective, as the extraction of raw materials, in particular, causes severe environmental damage, and the extraction of the raw materials required for the batteries is not sustainable. Furthermore, with the power-to-weight ratio currently achievable, batteries cannot be used in machines with high (peak) power requirements. Fuel cell-powered drives powered by renewably generated hydrogen meet the specified climate protection targets and are already in use to a very limited extent. However, this concept also has some disadvantages, such as low peak power and low economic efficiency compared to current diesel engines. Therefore, the focus has shifted to hydrogen combustion engines.which represent a promising propulsion alternative. However, to date, these exist almost exclusively in very small numbers or as demonstrators with a low degree of maturity. Hydrogen produced from renewable energies would meet all the requirements of "zero emissions," as it can be combusted without emissions. For example, in the passenger car sector, hydrogen engines with external mixture formation (PFI = port fuel injection) are used, in which the fuel is thoroughly mixed with air in a sufficient time before entering the combustion chamber. Hydrogen engines with direct injection of the fuel into the combustion chamber (internal mixture formation, DI = direct injection) play practically no role today, but compared to the PFI concept, they exhibit, among other things, higher efficiency,More stable combustion and the elimination of the risk of backfiring in the intake tract. Direct-injection hydrogen engines typically still differentiate with regard to the maximum injection pressure in the injector (< 60 bar: low pressure, > 60 bar: high pressure), although the limits are not clearly defined and the transitions are fluid. Higher pressures offer the potential for a shortened injection time in a later compression phase at higher combustion chamber pressures, resulting in increased efficiency and improved combustion stability. However, the overall efficiency decreases if hydrogen compression is required beforehand. If the hydrogen is produced 100% from renewable energies,Hydrogen combustion engines can achieve almost climate-neutral operation. Numerous other advantages are also offered: • Use of known, highly mature technologies and existing production facilities • Unlimited availability of hydrogen through water electrolysis • Use of the existing filling station system is possible (after appropriate conversion) with fast refueling times • (Almost) emission-free conversion of hydrogen during combustion is possible, as it is CO2-neutral, with only minimal CO, UHC, particulate and soot emissions (only caused by lubricants in the feed system, below the measuring limit) and only minimal NOx emissions through a suitable combustion process (if necessary with exhaust gas recirculation,SCR catalyst) • significantly lower requirement for hydrogen purity compared to fuel cell drives • no need for platinum for production as with fuel cells In addition to these numerous advantages over other drive concepts, there are also some challenges that have to be overcome in the development of hydrogen combustion engines: • low molecular weight of hydrogen,thus a low density associated with a low volumetric energy density (with a high mass-specific energy density); see Table 1 • Provision of a correspondingly high volume flow when injecting hydrogen • Corresponding provision of large flow cross-sections in the injector and thus required significantly larger strokes of the actuator than with conventional drive types • Associated development of a significantly stronger actuator unit with simultaneously limited installation space • Depending on the application, due to long injection and thus energization times of the actuator unit, a high thermal heat input and thus required heat dissipation concept • Lack of cooling of the injector unit by fuel, especially when injecting non-cryogenic hydrogen • Tightness of the entire system / prevention of external leaks,especially with regard to safety aspects (risk of fire and explosion due to hydrogen escaping from the system) • increased risk of wear on guides of moving components due to the practically non-existent lubricating effect of hydrogen • significantly greater tendency of moving components to bounce against mechanical stops in gas injectors compared to injectors with liquid fuels due to low damping effect during gas compression • material resistance to hydrogen necessary with regard to the risk of hydrogen embrittlement in mechanically stressed / pressurised components (reduced strength) or due to chemical reaction of the hydrogen with the oxygen present in the copper coil of the actuator (hydrogen disease of the copper) • mixture preparation in the combustion chamber / influence on the injection jet / ignition behaviour with very small quantities of injection • high local temperatures in the combustion chamber can lead to increased thermal NOx formation,which requires the development of a suitable combustion process (e.g. charge stratification to avoid stoichiometric combustion, exhaust gas recirculation, exhaust gas aftertreatment), Table 1: Mass and volume specific calorific value of diesel and hydrogen. The aim of the present invention is to at least partially overcome or mitigate the disadvantages listed above. In particular, the problem of the much more pronounced wear between the reciprocating parts as well as the problem of the pronounced bouncing that occurs with gas injectors compared to injectors with liquid fuels is to be addressed. The liquid fuels already have a damping or lubricating effect per se, so that an element surrounded by the fuel is dampened in its movement and experiences less wear when sliding along another element. The present invention succeeds in solving or mitigating at least one of the above-mentioned problems. For this purpose, an injector is to be provided that has all the features of independent claim 1. AdvantageousEmbodiments of the present invention can be found in the subclaims appended hereto. The invention describes an injector for injecting fuel, preferably for injecting a gaseous fuel, in particular hydrogen, comprising an injector housing for receiving and arranging injector components, an armature element which is arranged in the injector housing (which can be a pole tube) so as to be movable along an axial direction (i.e., the injector longitudinal direction) of the injector and is designed to close or release a throttle by an axial movement along the injector housing in order to allow fuel to flow through this throttle, a solenoid valve which is designed to transfer the armature element from a closing to a releasing state of the throttle and vice versa, an armature counterpart which is arranged on the side of the armature element opposite the throttle and in a state closing the throttleof the armature element defines a gap formed in the axial direction to the armature element, which corresponds to a maximum stroke of the armature element during a lifting process from the throttle, a non-magnetic or only weakly magnetizable bypass element for the targeted control of magnetic field lines, which is arranged at the level of the gap in or on the injector housing, viewed in the axial direction. The invention is characterized by a guide element which is attached to or arranged on an outer circumference of the armature element in order to enable a movement of the armature element in the axial direction relative to the injector housing that is as wear-free as possible when the throttle is opened and closed, wherein the guide element is spaced from the bypass element when the armature element has a minimum stroke in the axial direction. The guide element can be arranged on the outer circumference of the armature element or on an inner circumference of the injector housing, since regardless of the specifically selectedThe arrangement position prevents the armature element from directly contacting or rubbing against the inner circumference of the injector housing, thus resulting in reduced wear of these two components. Accordingly, according to the invention, it can be provided that the guide element is arranged on the armature element and serves to come into direct contact with an inner circumferential surface of the injector housing, or the guide element is arranged on the injector housing and serves to come into direct contact with an outer circumferential surface of the armature element. The wear of the armature element and the injector housing, both of which are typically made of metal, is thereby reduced, since the guide element prevents direct contact between the armature element and the injector housing during the back and forth movement of the armature element relative to the injector housing. Instead, the guide element is used, for example, as a sliding element. In addition, by arranging theThe positioning of the guide element at a distance in the axial direction from the bypass element ensures that there is an area between the bypass element and the guide element through which magnetic field lines can run essentially undisturbed, i.e. radially from a coil arrangement to the armature element. The positioning of the guide element in the area of ​​the magnetic circuit therefore does not have a noticeably negative effect on the actuation force of the solenoid valve. The reason for this is the distance in the axial direction of the guide element from the bypass element, as there is thus an area through which the magnetic field lines can propagate undisturbed, namely in a straight line in the radial direction (i.e. without detours around the guide element) to the armature element. The feature according to which the guide element is spaced from the bypass element in the axial direction with a minimal stroke of the armature element ensures that there is such an area through which the magnetic field lines can run undisturbed.can run towards the armature element. According to an optional modification of the present invention, it can be provided that the guide element is spaced apart from the bypass element in the axial direction at a maximum stroke of the armature element. This ensures that the magnetic field lines induced by a coil arrangement are not unnecessarily deflected and / or reduced in their magnetic force by the presence of the guide element. According to an advantageous modification of the invention, it can be provided that the guide element partially or completely surrounds an outer circumference of the armature element and is preferably made of a plastic or contains a plastic. In particular, the implementation of the guide element using plastic or an implementation in which the guide element contains plastic leads to particularly low wear, since plastic generally slides well on metal. According to an optional further developmentAccording to the present invention, it can be provided that the anchor element has regions of different diameters and the guide element is located in the region of the largest diameter of the anchor element or is arranged there. According to an advantageous modification of the present invention, it can be provided that the anchor element has an armature and a valve needle attached to the armature, or an armature and a valve needle engageable with the armature, wherein the diameter of the armature is larger than the diameter of the valve needle. As a rule, when the anchor element is designed with a valve needle, the injector also comprises a valve needle guide. Furthermore, according to the present invention, it can be provided that the guide element is a guide ring, a guide bushing, or a guide band. The guide element can be designed such that it completely or partially surrounds the outer circumference of the anchor element. According to a furtherIn an advantageous modification of the present invention, it can be provided that in the axial direction at the level of the gap, which can in particular be designed as an air gap, a coil arrangement or coil is provided which surrounds the gap circumferentially and is designed to provide a magnetic force for lifting the armature element from the choke, and preferably an iron yoke is provided which surrounds the coil arrangement on its outer circumference, wherein the iron yoke preferably serves to guide the externally running magnetic field lines of the coil arrangement through ferromagnetic material, so that no significant losses occur. According to a further optional modification of the present invention, it can be provided that the guide element is spaced apart from the coil arrangement in the axial direction at a minimum stroke (i.e. in the closed position) of the armature element. This also has the advantage that a course of the magneticField lines in the radial direction from the coil arrangement to the armature element is possible because the guide element, which disrupts the magnetic field lines, is spaced axially from the coil arrangement. Accordingly, there is a path for the magnetic field lines, in which they can run directly from the coil arrangement radially to the armature element without detours. Furthermore, according to the present invention, it can be provided that the end of the guide element facing the armature counterpart is partially or completely covered in the circumferential direction by the iron yoke during a minimal stroke of the armature element, in which the throttle is closed. It can therefore be provided that the coil element surrounds the injector housing on one outer circumferential side and the iron yoke encloses the coil arrangement with the exception of the side facing the injector housing. The coil arrangement is then enclosed on three sides by the iron yoke and on one side by the injector housing.surrounded, so that the coil arrangement is completely encapsulated. This has the advantage that magnetic field lines induced by the coil arrangement are guided (almost) without loss towards the injector housing by means of the iron return wire, where they can then act on the armature or the armature element to cause the desired lifting movement. According to the invention, it can also be provided that the guide element, at a minimum stroke of the armature element, is completely or partially covered in the circumferential direction by the iron return wire. According to a further advantageous modification of the present invention, it can be provided that the end of the guide element facing the armature counterpart is covered in the circumferential direction by the iron return wire in the axial direction at a maximum stroke of the armature element, in which the throttle is open. According to the invention, it can also be provided that the guide element, at a maximum stroke of the armature element, inCircumferential direction is completely or partially covered by the iron return. According to an optional development of the present invention, it can be provided that the iron return projects beyond the coil arrangement at one longitudinal end or at both of its longitudinal ends in the axial direction. According to an advantageous modification of the present invention, it can be provided that the armature element has at least one further guide element (hereinafter referred to as: secondary guide element) which is spaced apart from the guide element in the axial direction, wherein the secondary guide element is arranged in a region of the armature element which has a smaller diameter than the region of the armature element in which the guide element is arranged, preferably wherein the secondary guide element is attached or arranged circumferentially to a valve needle and the guide element is attached or arranged to an armature and / or the secondary guide element has the same properties as the guide elementAccordingly, it can be provided that the armature element has at least two guide elements, each spaced apart from one another in the axial direction. Such a configuration is particularly advantageous with regard to the probability of jamming of the armature element. According to a further optional development of the present invention, it can be provided that a volume is defined by the guide element and the secondary guide element arranged at a distance therefrom in the axial direction, which volume is minimal in a closed position of the armature element and maximal in a fully open position of the armature element, and wherein a fluid passage into or out of the volume is only possible by passing in the region of the guide element and / or the secondary guide element, so that a movement of the armature element when lifting off or placing on the throttle is damped. This damping is caused by theVolume only allows a fluid passage along the guide elements, which are generally in sliding contact with the housing or the armature element. Furthermore, it can be provided that the armature element, in particular a valve needle, has a connecting channel that connects the volume to a main flow path of the fuel, in particular a hollow channel of the valve needle, in order to influence a damping characteristic, preferably wherein the connecting channel is radially aligned and / or establishes a radially extending connection to a gap between the valve needle guide and the armature even when the armature element closes the throttle. According to this modification, a fluid passage to the volume is therefore not only possible by passing along the constriction formed by the guide element and the secondary guide element, but also through the specially provided connecting channel. According to an optional development of the present invention,It can further be provided that the volume for damping the movement of the armature element is adjusted by a compensating element arranged in the volume, in particular a compensating element made of an elastomer, preferably wherein the compensating element is elastically deformable in order to be compressed as a function of a pressure prevailing in the injector and to vary the damping volume as a function of the pressure prevailing in the injector. As a result, a damping characteristic can be adjusted using the compensating element, wherein the compensating element can consist of an elastomer, for example. The compensating element can be arranged in the gap between the valve needle guide and the armature, in particular on a valve needle guide. According to the present invention, it can also be provided that the compensating element, in a state in which the armature element closes the throttle, is in contact with the armature and is compressed by the closing force of the armature.state is / is maintained, preferably wherein the contact of the compensating element with the armature is broken during a lifting movement of the armature to release the throttle (e.g. because the compensating element is fastened to the valve needle guide). According to a further development of the present invention, it can be provided that the injector further comprises a retaining ring in order to fix the at least one guide element in the axial direction to the armature element, wherein the retaining ring consists of a metal or comprises this and is therefore easily magnetizable. Furthermore, according to the present invention, it can advantageously be provided that the armature element has at least two secondary guide elements in addition to the guide element, preferably wherein the guide element is designed such that it does not represent a guide in the classic sense, but merely defines a fluid gap between the armature element and the injector housing in order to ensure damping behavior when moving theAnchor element to be defined. The actual guidance is then provided by the two secondary guide elements, whereas the damping behavior can then be adjusted by the guide element by selecting a suitable circumferential gap to the injector housing. The invention further relates to an internal combustion engine with fuel injection, in particular with gas direct injection, in particular with hydrogen direct injection, comprising an injector according to one of the previously discussed aspects. Further features, details, and advantages of the invention will become apparent from the following description of the figures. These show: Fig. 1: a schematic sectional view of an injector according to the prior art, Fig. 2: a schematic sectional view of an injector according to the prior art in an alternative embodiment, Fig. 3: a schematic sectional view of two injectors to compare a closed and an openInjector valve, Fig. 4: a schematic sectional view of an injector with two guide elements mounted on the valve needle, Fig. 5: a schematic sectional view of an injector with two guide elements integrated in the valve needle guide, Fig. 6: a schematic sectional view of an injector according to the invention in which the valve needle and armature are formed in one piece, Fig. 7: a schematic sectional view of an injector with two guide elements mounted on the valve needle, Fig. 8: a schematic sectional view of an injector with two guide elements mounted on the valve needle, Fig. 9: a schematic sectional view of an injector according to the invention in which the valve needle and armature are formed in two parts and have the guide elements, Fig. 10: a schematic sectional view of an injector according to the invention in which the valve needle and armature are formed in two parts and the guide elements are in a valve needle guide and aInjector housing are arranged, Fig. 11: a schematic sectional view of an injector according to the invention with a compensating element in the volume delimited by the guide elements, Fig. 12: a schematic sectional view of an injector according to the invention in which a guide element is fixed with a retaining ring, Fig. 13: a schematic sectional view of an injector according to the invention, Fig. 14: various embodiments of guide elements, and Fig. 15: a diagram explaining the armature stroke over time in comparison with and without damping volume, Fig. 16: a schematic sectional view of an injector according to the invention with a ballistically moving coupling element (sleeve) and inlet-side damping volume; Fig. 17: a schematic sectional view of an injector according to the invention with pressure equalization connections of inlet-side damping volume and central fluid path in the coupling element; Fig. 18: a schematic sectional view of an injector according to the inventionwith pressure equalization connections in the armature; Fig. 19: a schematic sectional view of an injector according to the invention with pressure equalization connections in the armature counterpart; Fig. 20: a schematic sectional view of an injector according to the invention with an axial residual air gap between the armature and the armature counterpart in the open state, realized via the coupling element; Fig. 21: a schematic sectional view of an injector according to the invention with an additional stop / damping element; Fig. 22: a schematic sectional view of an injector according to the invention with an inlet-side stop for the coupling element with stroke limitation of the armature via the stop of the armature on the armature counterpart; Fig. 23: a schematic sectional view of an injector according to the invention with an inlet-side stop for the coupling element with stroke limitation of the armature and adjustment of the axial residual air gap via the stop of the coupling element; Fig. 24: a schematic sectional view of an injector according to the invention withStop / damping element; Fig. 25: a schematic sectional view of an injector according to the invention with spring plate and stop / damping element; Fig. 26: a schematic sectional view of an injector according to the invention with spring plate and stop and damping element; Fig. 27: a schematic sectional view of an injector according to the invention with guide bands in the coupling element; Fig. 28: a schematic sectional view of an injector according to the invention with guidance in the armature counterpart; Fig. 29: a schematic sectional view of an injector according to the invention with guide bushing in the armature counterpart; Fig. 30: a schematic sectional view of an injector according to the invention with an elastic tensioning element (e.g. spring) and movable on the armature counterpart; Fig. 31: a schematic sectional view of an injector according to the invention with an elastic tensioning element as a prestressed elastomer and guide piece between the armature counterpart and the housing; and Fig. 32: a schematic sectional view of ainjector according to the invention with an additional sleeve in the armature. The following detailed description of the figures is explained using an injector for injecting a gaseous fuel, although it will be clear to the person skilled in the art that the invention also encompasses an injector for injecting another, for example, liquid fuel. Fig. 1 shows a longitudinal section of an injector 1 for injecting a gaseous fuel, for example hydrogen, into a combustion chamber. The injector 1 has an injector housing 2 (which also functions as a connecting tube), in which various components of the injector 1 are located. On the connection side, a fuel supply line 13 is provided for introducing a fuel into the injector 1. First, the fuel or another combustible fluid (for example hydrogen) is fed through a bore of a cover 12 running approximately centrally in the injector housing 2 and then through a fluid channelan armature counterpart 7, the hollow interior of the armature 3 and a valve needle 4, which can be designed as a hollow needle, to the end of the valve needle 4 remote from the connection side. The needle 4 and the armature 3 can be designed in one or more parts. In this case, the needle 4 and the armature 3 are preferably firmly connected to one another, e.g., by force. A design with a freewheel between the needle 4 and the armature 3, so that the armature 3 only comes into contact with the needle 4 after a certain run-up distance and carries it along by force transmission through contact, is, however, also conceivable and also encompassed by the invention. Depending on the position of the armature 3 or the valve needle 4 relative to the valve plate 15, the at least one throttle 5 penetrating the valve plate 15 is closed or opened. In the state shown in Fig. 1, the throttles 5 are closed by the pressing of the valve needle 4 against the valve plate 15, since the end face of the valve needle 4 forms the opening contoursof the throttles 5. If the throttles 5 are closed by the end face of the valve needle 4, the fluid flow of the fuel is stopped at this point of the injector 1 and there is no downstream flow of fuel beyond the valve plate 15. If, on the other hand, the throttles 5 are opened, which is implemented by the armature 3 being lifted away from the valve plate 15 and the resulting lifting of the valve needle 4, the fuel introduced into the injector 1 at a certain pressure flows out and exits via the plurality of throttles 5 on the side of the valve plate 15 spaced apart from the armature 2. As a result, the pressurized fuel flows out of the injector 1 through the injection cap 23. After flowing through the injection cap 23, the fuel delivered by the injector 1 is then typically located outside the injector 1 in a combustion chamber. In addition, a compression of thefuel, where the fuel is then ignited or is ignited. The armature 3 (together with the valve needle 4) can be moved back and forth in the longitudinal direction of the injector 1. The movement of the armature 3, which can be formed integrally or permanently connected to the valve needle 4, is controlled via an active valve, which in the present illustration in Fig. 1 is a solenoid valve 6. The armature 3 is designed such that it reacts to the magnetic force generated by a coil arrangement 17. Current can optionally flow through the coil arrangement 17 in such a way that the resulting magnetic force moves the armature 3 in the direction of the fuel inlet. This causes the armature 3 to move away from the valve plate 15, which movement runs counter to the force exerted on the armature 3 by the armature spring 14. As a result of the lifting of the valve needle 4, the throttles 5 in the valve plate 15 are released, so that the valve plate 15Fuel can flow through it. For precise guidance of the valve needle 4 along the longitudinal axis X of the injector (hereinafter also referred to as the axial direction), a valve needle guide 19 can be provided, which circumferentially encloses an outer side of the valve needle 4. An air gap 18 is provided between the armature 3 and the armature counterpart 7, which is closed or reduced when the coil 17 is energized. In order to improve the magnetic flux 24 when the active valve 6 is implemented as a solenoid valve, the coil 17 can be surrounded on its outer circumferential side by an iron yoke 21, so that the magnetic field can propagate particularly well there. The situation is similar with the housing component directly surrounding the armature element 3 and the armature counterpart 7, which is also preferably made of a magnetizable material. It can be advantageous if the pole tube or the injector housing 2, which is a component of the injector 1, is alsomade of iron or another ferromagnetic material. The same applies to the armature counterpart 7, which advantageously also consists of a magnetizable material. A visual representation of the magnetic field lines 24 is illustrated by the dotted, closed line that runs around the coil 17. Due to the magnetic force, the armature 3 (together with the valve needle 4) is pulled towards the armature counterpart 7 and thus lifted from the valve plate 15 or from the throttles 5 breaking through the valve plate 15, so that fuel flows towards the injection cap 23, from where the fuel is introduced into the combustion chamber. The armature 3 has a correspondingly designed clearance to the housing so that it does not come into contact with the housing 2 and does not rub against it and is not exposed to particularly high wear. In order to guide the magnetic flux lines 24, preferably through the axial working air gap 18 betweenTo guide the magnetic field between the armature 3 and the armature counterpart 7 (preferably coaxially to the axial direction) and thus significantly increase the magnetic force, it is advantageous to introduce a recess in the housing 2 at the level of the working air gap 18 or to create a non-magnetic or only weakly magnetizable one- or multi-part intermediate ring across the entire or partial thickness of the housing 2, e.g., by means of a welded connection. This is referred to below as "bypass 20." The armature counterpart 7 is fixedly arranged in the injector's longitudinal direction and preferably has no play (although there are also implementations encompassed by the invention in which the armature counterpart is designed to be movable). Thus, the armature counterpart 7 is fixed between an adjusting element 8, which allows fine adjustment in the axial direction, and the cover 12. The adjusting element 8 is typically made of metal and serves to adjust the position of the armature counterpart 7 with respect to the injector's longitudinal direction.to be precisely specified. Thus, during the manufacture of the injector 1, depending on the tolerances of the injector components, a correspondingly selected adjustment element can be installed so that the distance in the injector's longitudinal direction between the armature 3 and the armature counterpart 7 corresponds to a predetermined value when the valve is in the closed position. As described above, however, this presents the problem that, during an opening process of the injector 1, the armature 3 impacts against the armature counterpart 7 with high kinetic energy, resulting in bouncing. Particularly when using a gaseous fuel, the damping effect of a fuel used in liquid form to reduce the bouncing of the armature 3 against the armature counterpart 7 is lacking. Fig. 2 shows the injector according to the previously described alternative embodiment with a one-piece armature element 3, 4 in which the armature 3 and needle 4 are implemented in a single component. The armature element 3, 4 is guided directly in the housing 2.which, in contrast to the above-discussed Fig. 1, has a continuous bypass ring 20. Figs. 3A and 3B, taken as a whole, show a schematic sectional view of two injectors, comparing a closed and an open injector valve. A possible fuel path through injector 1 during fuel injection can be seen in Fig. 3B. In Fig. 3A, the injector needle 4 is placed on the throttles 5 of the valve plate 15 in such a way that no fluidic connection can occur from the inlet of the injector to the outlet. Only when the injector needle 4 is lifted, which occurs due to the magnetic force induced in the armature 3 via the coil 17, are the throttles 5 opened, creating a continuous fuel path to the outlet. If a voltage signal is applied by a control device via electrical contacts to the coil 17 of the actuator 6, the current in the electrical circuit increases to a defined final level. The current-carrying coil 17induces a magnetic field in the actuator, the magnetic field lines 24 of which spread toroidally around the coil 17. The magnetic field builds up a magnetic force in the (working) air gap 18 between the armature 3 and the armature counterpart 7, whereby the armature 3 is attracted to the armature counterpart 7 as soon as the magnetic force exceeds the closing force (sum of the preload force of the armature spring 14 and the pressure forces on the needle 4 and the armature 3). The armature 3 is advantageously fixedly connected to the valve needle 4 or is a one-piece armature-valve needle component (e.g. an armature element 3, 4), so that the valve needle 4 preferably moves uniformly with the armature 3. As soon as the valve needle 4 no longer closes the at least one throttle 5, the connection between the needle chamber and the injection chamber is released, so that the fuel flows from the needle chamber into the injection chamber and finally into the combustion chamber. When the anchor 3 hits the upper stop 7, this usually results ina relatively strong bouncing behavior, which negatively affects the controllability of the fuel injection quantity. To end the injection process, the voltage supply is terminated by a control unit, so that the current through the coil 17 is reduced to zero. This also reduces the magnetic field. As soon as the magnetic force is low enough, the needle 4 and armature 3 begin to close, preferably uniformly. If the end face of the needle 4 closes at least one throttle 5 in the valve plate 15 again, the connection between the needle chamber and the injection chamber is severed, the fuel flow is interrupted, and the fuel injection is terminated. Here, too, a relatively strong bouncing behavior generally occurs, which negatively affects the controllability of the fuel injection quantity. Fig. 4 shows the injector 1 with at least one guide element 26 attached to the needle 4, with exactly two axially spaced apart from each other in the present case.spaced guide elements 26 are provided. The guide element 26 can be a guide band, a guide ring and / or a guide bushing. Preferably, the guide element is made of plastic or contains plastic. The guidance between needle 4 and needle guide 19 is thus low-wear due to significantly lower friction compared to a metal-to-metal guide without guide element(s). Fig. 5 shows a similar implementation as in Fig. 4. However, here the guide bands are integrated into the needle guide. The effects achievable do not differ from those in Fig. 4. Fig. 6 shows the injector in an alternative embodiment according to Fig. 2, in which the armature 3 and the valve needle 4 are formed by a one-piece armature element 3, 4. In order to improve guidance and reduce friction, it is advantageous to space the two guide bands 25, 26, which are spaced apart from one another in the axial direction, as far apart as possible in the axial direction.spaced apart in order to select the ratio of guide length (distance between the two guide bands 25, 26) to the diameter (of the respective guides), called the L / D ratio for short, as large as possible. For this purpose, it can be advantageous to move the inlet-side guide ring 25 into the effective range of the electromagnetic actuator 6, 17, even if this can negatively influence the provided magnetic force according to the prior art. Fig. 7 shows the injector 1 in a form in which the armature 3 is pressed into the inside of the valve needle 4 instead of being pressed on the outside, in such a way that the compression area on the inlet side lies outside the area of ​​the guide elements 26, which in this case are designed as guide bands. Fig. 8 shows a similar embodiment to Fig. 7, but with the compression in the area between the guide elements 26. In both cases, the influence of the compression on the guide area of ​​the guide elements should be minimized. Fig. 9 showsthe injector 1 in one embodiment of the invention with at least two guide elements 25, 26, in which the inlet-side guide element 25 is integrated in the region of the magnet 6. It is particularly advantageous if the guide element 25, when the injector 1 is in a closed state, in which the armature 3 or the valve needle 4 fixedly connected to the armature 3 is arranged such that the throttle 5 is closed, is not covered in the radial direction by the bypass element 20 and / or the coil arrangement 17. In other words, there is a distance in the axial direction between the guide element 25 and the bypass element 20 and / or the coil arrangement 17. This ensures that when a magnetic field is formed by the coil arrangement 17, magnetic field lines can be generated that can extend straight in the radial direction toward the armature 3, so that a strong magnetic force is formed to lift the armature 3 from a closed position.can be. However, if there is no possibility for magnetic field lines to extend in a straight line in the radial direction towards the armature 3, e.g. because the guide element 25 makes such a formation of magnetic field lines difficult or even prevents it, this leads to a decrease in the magnetic force acting on the armature 3, which results in a slower lifting of the armature 3 from its closed position. Furthermore, it can be seen in the area shown enlarged in Fig. 9 that the guide element 25 in conjunction with the secondary guide element 26 defines a volume 27, which is referred to as the damping volume 27. The damping volume 27 can only release or absorb absorbed fluid via a passage along the guide element 25 or the secondary guide element 26. Since the guide element 25 or the secondary guide element 26 usually have a sliding contact with the injector housing 2 or the valve needle guide 19 (whereby aSliding contact with the valve needle 4 or the armature 3 (which is covered by the invention), a sudden lowering of the armature 3 induced by tensioning the spring 14 towards its closed position can be dampened. The same also applies to the movement towards the open position of the valve, since the very small fluid passage along the guide element 25 or the secondary guide element 26 counteracts the lifting movement. Reference numeral 28 represents a connecting channel in the valve needle, which enables adjustment of the damping effect of the damping volume 27. By deliberately providing such a connection 28, which connects the damping volume 27 with the main flow channel of the fuel to be dispensed by the injector, the damping effect of the damping volume 27 can be adjusted. In the enlarged view in Fig. 9, the fluid flowing from the damping volume 27 into the main flow channel istwo small arrows pointing towards each other. In this case, the at least one connecting channel connects the interior of the hollow needle with the volume. Fig. 10 shows a similar illustration to Fig. 9, except that the guide elements 25, 26 are again mounted in the needle guide 19 and housing 2 instead of on the valve needle 4 and armature 3. If the injector 1 is designed such that the inlet-side guide diameter D2 is at a different, preferably larger diameter than the outlet-side guide diameter D1, a fluid-filled volume 27 (here called the damping volume) is also formed between the valve needle guide 19 or housing 2 and armature 3. This volume, when the needle 4 or armature 3 moves, generates a negative or positive pressure due to expansion and compression, thus counteracting the movement of the needle 4 and armature 3 and slowing down the movement. This results in a dampened behavior and a reduction in bouncing during opening andClose. The damping behavior can be adjusted via the size of the damping volume, optional connecting bores 28 between the damping volume and the needle chamber, as well as the guide play of the guide elements 25, 26. In particular, the inlet-side guide element 25 can be designed such that it does not represent a guide in the classic sense, but that it merely defines the fluid gap between the armature and the housing and thus the damping behavior, and the guidance is provided via the outlet-side guide element 26 and optionally at least one further (central) guide element 26, which is arranged between the outlet-side guide element and the central guide element. Fig. 11 shows a supplementary embodiment in which the damping volume 27 and thus the damping behavior can be adjusted via a compensating element 29. In particular, this compensating element 29 can be elastically deformable and, for example, consist of an elastomer, which, depending on the pressure in the injector,is pressed and the damping volume 27 varies. It can be advantageous for the elastic damping volume 27 to be designed such that, when the injector 1 is closed, it is in contact with the armature 3 and fills the damping volume 27 as much as possible, thus keeping it small. This results in the greatest possible expansion ratio when the armature 3 moves. Fig. 12 shows a supplementary embodiment of the present invention, in which at least one guide element 25, 26 is fixed in its position by a ring 30. For the inlet-side guide element 25, it is advantageous if this ring 30, which is referred to as a retaining ring, is easily magnetizable. The provision of the retaining ring 30 enables simple installation of the guide element 25 during assembly of the injector 1. Fig. 13 shows the inventive positioning of the inlet-side guide element 25. By keeping the guide element 25 as far away as possible from the secondary guide element 26,the ratio of guide length (distance between both guide bands 25, 26) to the diameter (of the respective guides D1, D2), called the L / D ratio for short, increases. A larger L / D ratio reduces the misalignment of needle 4 and / or armature 3 during operation, which reduces the risk of jamming and wear due to reduced friction. The disadvantage here is that the magnetic force can be reduced compared to variants with guide elements outside the magnetic circuit. The loss of magnetic force can be minimized by careful design of the thickness, length and position of the guide element 25 on the armature 3. According to the invention, it is advantageous to space the inlet-side guide band 25 from the bypass element 20 in such a way that there is a circumferential (cylindrical) overlap of the outer armature and inner housing surface axially between the guide element 25 (e.g. a guide band) and the bypass element 20, so that magnetic field lines 24, which (on the outlet side) lie below theCoil 17 runs through the housing 2, preferably between the guide element 25 and the bypass element 20, merging radially from the housing 2 into the armature 3. The distance in the axial direction X is preferably selected such that the magnetic flux runs through the working air gap 18 in the axial direction, thus reducing the magnetic force as little as possible or not at all. Referring to the local coordinate system inserted in Fig. 13, in which the lower edge of the iron return wire has the position x1 (seen in the axial direction), the outlet-side end of the inlet-side guide element has the position x2, the inlet-side end of the inlet-side guide element has the position x3, and the outlet-side end of the bypass has the position x4, it is therefore advantageous that the following conditions apply: ^ x1≤x3≤x4^ x2 <x3 (per Definition, da das Führungselement eine in axialer Richtung verlaufende Ausdehnung besitzt) ^ x0≤x2 (optional, falls Durchmessersprung, wobei x0 die Position einesDiameter jump to the housing or from the valve needle and / or housing in the axial direction) Advantageously, it is provided that the above conditions are met at a minimum and / or a maximum stroke of the valve needle. As a further advantage of this design, in the optional design with diameter variation from D1 to D2 between the inlet-side guide element 25 and the outlet-side secondary guide element 26 (diameter jump at x0) between the armature 3 and the needle guide 19 or the housing 2, an (almost) closed volume 27 is created, through which fluid can only flow in and out via the radial guide gaps of the guide elements 25, 26 or optional connecting bores 28. This volume 27 therefore has a damping effect during expansion (opening of needle 4 / armature 3) and compression (closing of needle 4 / armature 3) (negative pressure or positive pressure due to adiabatic or polytropic expansion or compression of the fluid, in particular the gas, acts on theMovement direction of needle 4 / armature 3 by the acting pressure forces on the surfaces with an axial portion of the respective normal vectors). The damping behavior can be adjusted, among other things, via the guide clearance of the guide elements 25, 26. However, it is also conceivable to adjust the damping behavior via the size of the connection between the damping volume and the main flow, the diameter D1 and D2 as well as the initial volume of the damping volume and the maximum needle stroke. This can reduce the bouncing during opening and closing. By very tight guidance in the area of ​​the needle 4, it is also possible according to the invention to operate with the damping volume 27 without the need for the inlet-side guide band 25 in the armature 3. The guide clearance between the armature 3 and the housing 2 would have to be adjusted accordingly. Fig. 14 shows various embodiments of the guide elements 25, 26. These can be circumferentially symmetrical (as in Fig. 14 A) or have an interruption (as in Fig. 14 B) incircumferential direction. The latter can be advantageous for assembly. Fig. 15 shows a diagram illustrating the improved bounce behavior due to the damping volume. It can be clearly seen that injectors 1 with a damping volume 27 have a lower bounce characteristic than injectors 1 without such a damping volume. This is particularly advantageous because fuel leaves the injector during bounce, although this is not intended. In addition, the fuel dispensed during bounce is difficult to predict, so that the quality of control with regard to the fuel delivery quantity suffers. Further embodiments are listed below which further improve the damping behavior of the injector during opening and closing. In the above embodiments, a damping volume was introduced on the outlet side of the armature (see Fig. 16). By introducing a coupling element (a sleeve), which counteracts the spring force on the armaturetransmits, an additional damping volume can be created on the inlet side of the armature between the armature and the armature counterpart (see Fig. 16). This creates an overpressure when the armature needle opens due to compression, and a negative pressure when closing, which counteracts the movement of the armature needle and thereby dampens the impact during opening and closing by reducing the impact speed. The coupling element is preferably made of a non-magnetizable or only weakly magnetizable material and is guided in the armature counterpart. The coupling element is preferably rotationally symmetrical, in particular designed as a sleeve (hollow cylinder). The coupling element can also be designed in such a way that transverse forces introduced by the spring onto the armature are reduced. The sleeve can preferably be coated. Possible processes for hardening the surface (coating, heat treatment, etc.) are recommended, particularly on the contact surfaces of the armature and sleeve.In the first embodiment in Fig. 16, the inlet-side damping volume is limited by the contact between the armature and the coupling element, the guide gap between the coupling element and the armature counterpart, and optionally at least one guide band between the armature and the housing (or an armature guide) (approximately closed volume). Upon contact between the armature and the armature counterpart upon opening of the armature needle, the coupling element detaches from the armature due to mass inertia and continues to fly ballistically until it reverses its direction due to the acting spring force and is accelerated again until it impacts the inlet-side armature face. This can lead to bouncing of the armature on the armature counterpart and bouncing between the armature and the coupling element upon re-contact. During the lift-off period between the armature and the coupling element, a fluid connection is created between the inlet-side damping volume and the main flow path of the fuel along the injector axis.established, so that pressure equalization occurs between the main flow and the inlet-side damping volume. The bouncing of the armature needle during closing can also cause a slight lifting of the coupling element and thus pressure equalization. This is advantageous in order to achieve a stable open state (plateau phase of the injection rate) after opening and a stable closed state after closing. Fig. 17 shows a further embodiment in which at least one fluid connection is additionally specifically introduced in the coupling element between the inlet-side damping volume and the main flow path of the fuel. These could be holes in the sleeve or slots / grooves etc. on the end face of the sleeve. By appropriately designing the connections, the damping behavior can be specifically controlled. The fluid connections should preferably be symmetrical in order to avoid unnecessary transverse forces due to pressure forces. Fig. 18 shows aAnother embodiment in which pressure equalization is realized via at least one fluid connection in the armature. Fig. 19 shows another embodiment in which pressure equalization is realized via at least one fluid connection in the armature counterpart. Fig. 20 shows another embodiment in which the coupling element is used to adjust an axial residual air gap (aRLS) in the fully open state of the armature needle. Fig. 21 shows another embodiment like Fig. 20, in which the impact of the sleeve during opening is cushioned by a stop / damping element, which preferably consists entirely or partially of an elastomer. Fig. 22 shows another embodiment in which the stroke of the armature needle is adjusted via the first adjustment part (adjusting disk) and the stroke of the coupling element is limited in the ballistic flight phase by an inlet-side stop. Fig. 23 shows another embodiment like Fig. 22, in which the stroke of the coupling element is furtheris limited so that the stroke of the needle armature is limited to the same stroke (aRLS is adjusted via the coupling element). Fig. 24 shows a further embodiment as in Fig. 23, in which the inlet-side stop of the coupling element is designed to be soft-elastic, preferably a stop / damping element made of elastomer. Fig. 25 shows a further embodiment in which the force is transmitted from the spring to the sleeve via a further intermediate piece (spring plate). Optionally, a stop / damping element can again be integrated. Advantageously, the sleeve and spring plate can be made of different materials. In addition, the shape of the sleeve (e.g., as a hollow cylinder) can be designed very simply and manufactured precisely. A separate coating of the sleeve, e.g., on the outer, guided surface, is also conceivable. The material of the sleeve can be matched to the material of the armature counterpart with regard to friction. Fig. 26 shows a further embodiment as inFig. 25, in which a damping element is integrated between the coupling element and the spring plate. An additional stop element for the spring plate is optionally possible. Fig. 27 shows a further embodiment with at least one guide band / guide ring / guide bushing on the coupling element. This allows for low-wear guidance, similar to the guide elements on the anchor needle. Fig. 28 shows a further embodiment as in Fig. 27, in which at least one guide band / guide ring / guide bushing is integrated in the armature counterpart to guide the coupling element. Fig. 29 shows a further embodiment as in Fig. 28, in which the guide element is designed as a bushing. Fig. 30 shows a further embodiment in which the armature counterpart is movably mounted and not fixed. The armature counterpart is pre-tensioned by an elastic tensioning element (e.g. a spring). When the armature impacts the armature counterpart, part of theImpulse from the armature to the armature counterpart (elastic-plastic impact). This reduces the bouncing of the armature during opening. In addition, the transmitted impact forces are reduced. The preload force of the elastic tensioning element (here placed between the armature counterpart and the cover) is preferably greater than the preload force of the needle spring. Fig. 31 shows a further embodiment like Fig. 30, in which the movable armature counterpart is guided by means of at least one guide band / guide ring / guide bushing. Here, too, an arrangement on the outer diameter of the armature counterpart or on the inner diameter of the housing (or an armature counterpart guide) is possible. Furthermore, here, for example, the elastic tensioning element is designed as an elastomer instead of a spring, which enables an additional damping effect. In order to reduce wear on the contact surface of the armature and coupling element (sleeve), a coating of the armature and / or sleeve is required, at least onthe contact surfaces is conceivable. Alternatively, a stop sleeve, as shown in Fig. 32, could also be implemented in the armature, which is connected to the armature, for example, by a press fit. The stop sleeve can be made of hard metal or ceramic, for example. Preferably, the surface hardness of the stop sleeve and the coupling element (sleeve) are different.

[0002] 1 Injector 2 Injector housing 3 Armature; Part of an armature element 4 Valve needle, part of an armature element 5 Throttle 6 Solenoid valve 7 Armature counterpart 8 Armature-side stop 9 Inlet-side stop 10 Inlet-side damping element 11 Armature-side damping element 12 Cover 13 Supply line 14 Armature spring 15 Valve plate 17 Coil 18 Air gap 19 Needle guide 20 Bypass element 21 Iron return / housing section 22 Injection pipe 23 Injection cap 24 Course of magnetic field lines 25 Guide element 26 Secondary guide element 27 Damping volume 28 Connecting bore 29 Compensating element 30 Retaining ring 31 Coupling element, e.g. sleeve 32 Pressure compensation connection(s) 33 Stop / damping element 34 Inlet-side stop for coupling element (sleeve) 35 Spring plate 36 Stop element 37 Damping element 38 Coupling element guide bands 39 Coupling element guide bushing 40 Elastic clamping element 41 Anchor counterpart guide bands 42 Stop sleeve X Axial direction of the injector

Claims

00624-24 La / Se Liebherr-Components Deggendorf GmbH DE - Deggendorf ^ ... a solenoid valve (6) which is designed to transfer the armature element (3, 4) from a closing to a releasing state of the throttle (5) and vice versa, an armature counterpart (7),which is arranged on the side of the armature element (3, 4) opposite the throttle (5) and, in a state of the armature element (3, 4) closing the throttle (5), defines a gap (18) extending in the axial direction (X) to the armature element (3, 4), which gap corresponds to a maximum stroke of the armature element (3, 4) during a lifting process from the throttle (5), a non-magnetic or only weakly magnetizable bypass element (20) for the targeted control of magnetic field lines (24), which is arranged in or on the injector housing (2) at the level of the gap (18) viewed in the axial direction (X), - 2 - characterized by a guide element (25) which is attached to or arranged on an outer circumference of the armature element (3, 4) in order to enable the armature element (3, 4) to move in the axial direction (X) relative to the injector housing (2) with as little wear as possible during opening and closing of the throttle (5), wherein the guide element (25) is spaced apart from the bypass element (20) in the axial direction during a minimal stroke of the armature element (3, 4).

2. Injector (1) according to the preceding claim, wherein the guide element (25) is arranged on the armature element (3, 4) and serves to come into direct contact with an inner circumferential surface of the injector housing (2), or the guide element (25) is arranged on the injector housing (2) and serves to come into direct contact with an outer circumferential surface of the armature element (3, 4). 3.Injector (1) according to one of the preceding claims, wherein the guide element (25) partially or completely surrounds an outer circumference of the armature element (3, 4) and is preferably made of a plastic or contains a plastic.

4. Injector (1) according to one of the preceding claims, wherein the armature element (3, 4) has regions of different diameters and the guide element (25) is attached or arranged in the region of the largest diameter of the armature element (3, 4).

5. Injector (1) according to one of the preceding claims, wherein the armature element (3, 4) has an armature (3) and a valve needle (4) fastened to the armature (3), or an armature (3) and a valve needle (4) engageable with the armature (3), wherein the diameter of the armature (3) is larger than the diameter of the valve needle (4). - 3 - 6. Injector (1) according to one of the preceding claims, wherein the guide element (25) is a guide ring, a guide bushing, or a guide band.

7. Injector (1) according to one of the preceding claims, wherein in the axial direction at the level of the gap (18), which can in particular be designed as an air gap, a coil arrangement (17) is provided which circumferentially surrounds the gap (18) and is designed to provide a magnetic force for lifting the armature element (3, 4) from the throttle (5), and an iron yoke is provided which surrounds the coil arrangement (17) on its outer circumference, wherein the iron yoke preferably serves to guide the externally running magnetic field lines of the coil arrangement (17). 8.Injector (1) according to the preceding claim 7, wherein the end of the guide element (25) facing the armature counterpart (7) is circumferentially covered by the iron yoke during a minimum stroke of the armature element (3, 4) in which the throttle (5) is closed.

9. Injector (1) according to one of the preceding claims 7 or 8, wherein the end of the guide element (25) facing the armature counterpart (7) is circumferentially covered in the axial direction by the iron yoke during a maximum stroke of the armature element (3, 4) in which the throttle (5) is open.

10. Injector (1) according to one of the preceding claims 7-9, wherein the iron yoke projects beyond the coil arrangement (17) at one longitudinal end or at both longitudinal ends in the axial direction.Injector (1) according to one of the preceding claims, wherein the anchor element (3, 4) has at least one further secondary guide element (26) which is spaced apart in the axial direction from the guide element (25), wherein the secondary guide element (26) is arranged in a region of the anchor element (3, 4) which has a smaller diameter than the region of the. - 4 - Anchor element (3, 4) in which the guide element (25) is arranged, preferably wherein the secondary guide element (26) is attached or arranged circumferentially to a valve needle (4) and the guide element (25) is attached or arranged to an armature (3) and / or can have the same properties as the guide element (25).

12. Injector (1) according to the preceding claim 11, wherein a volume is defined by the guide element (25) and the secondary guide element (26) arranged at a distance therefrom in the axial direction, which volume is minimal in a closed position of the armature element (3, 4) and maximal in a fully open position of the armature element (3, 4), and wherein a fluid passage into or out of the volume is only possible by passing through the guide element (25) and / or the secondary guide element (26), so that a movement of the armature element (3, 4) is damped when it is lifted off or placed on the throttle (5). 13.Injector (1) according to the preceding claim 12, wherein the armature element (3, 4), in particular a valve needle (4), has a connecting channel (28) which connects the volume to a main flow path of the fuel, in particular a hollow channel of the valve needle (4), in order to influence a damping characteristic, preferably wherein the connecting channel (28) is radially aligned and / or establishes a radially extending connection to a gap between the valve needle guide and the armature (3) even when the armature element (3, 4) closes the throttle (5).Injector (1) according to one of the preceding claims 12 or 13, wherein the volume for damping the movement of the anchor element (3, 4) is adjusted by a compensating element (29) arranged in the volume, in particular a compensating element (29) made of an elastomer, preferably wherein the compensating element (29) is elastically deformable in order to be compressed as a function of a pressure prevailing in the injector (1) and to vary the damping volume as a function of the pressure. - 5 - 15. Injector (1) according to the preceding claim 14, wherein the compensating element, in a state in which the armature element (3, 4) closes the throttle (5), is in contact with the armature (3) and is held in a compressed state by the closing force thereof, preferably wherein the contact of the compensating element with the armature (3) is broken during a lifting movement of the armature (3) to release the throttle (5).

16. Injector (1) according to one of the preceding claims, further comprising a retaining ring (30) for fixing the at least one guide element (25, 26) in the axial direction to the armature element (3, 4), wherein the retaining ring (30) consists of or comprises a metal and is therefore readily magnetizable.Injector (1) according to one of the preceding claims, further developed with the features of claim 11, wherein the anchor element (3, 4) has at least two secondary guide elements (26) in addition to the guide element (25), preferably wherein the guide element (25) is designed such that it does not represent a guide in the classic sense, but merely defines a fluid gap between the anchor element (3, 4) and the injector housing (2) in order to define a damping behavior when the anchor element (3, 4) moves.

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