Injector for injecting fuel

Abstract

The present invention discloses a hydromechanical hybrid gear device with a plurality of power distribution modes, and an associated control method. The gear device comprises an input shaft, a distribution mechanism, a mechanical gear assembly, a hydraulic gear assembly and an output shaft. As a result of the use of a one-way clutch in the mechanical gear change device, a homogeneous use of the individual gear change elements in order to extend the service life can be achieved in addition to enabling motor braking.

Description

[0001] i

[0002] Injector for injecting fuel

[0003] The present invention relates to an injector for injecting fuel, in particular for injecting a gas, preferably for directly injecting hydrogen. The injector can be designed to inject fuel into a combustion chamber of an internal combustion engine.

[0004] As emissions standards become increasingly stringent worldwide and ambitious climate protection goals are set, the environmental requirements for internal combustion engines are steadily increasing. The goal in the foreseeable future is low-emission or even zero-emission drive technologies that meet even the most stringent emissions standards and make a significant contribution to achieving climate protection goals. For combustion-based technologies, these goals can only be achieved through the use of climate-neutral, renewably produced fuels that produce no emissions along the entire value chain (so-called "zero-emission" fuels).

[0005] With current conventional gasoline, diesel, and gas engines, the requirements for emission-free combustion cannot be met - even when using so-called e-fuels, e.g. a synthetically produced OME fuel, the production of which requires only renewable energy - because the emission of harmful exhaust gases such as nitrogen oxides (NOx), unburned hydrocarbons (UHC), and soot cannot be completely reduced with current technologies.

[0006] 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, the production of (lithium) batteries is very energy-intensive and problematic from an environmental perspective, as significant environmental damage occurs, particularly during raw material extraction, and the extraction of the raw materials required for batteries is not sustainable. Furthermore, the power-to-weight ratio of batteries that can be achieved today does not allow their use in machines with high (peak) power requirements.

[0007] Fuel cell-powered drives powered by renewably produced 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.

[0008] The focus has therefore shifted to hydrogen combustion engines, which represent a promising alternative propulsion system. However, to date, these engines exist almost exclusively in very small numbers or as demonstrators with a low level of maturity. Hydrogen produced from renewable energies would meet all the requirements of "zero emissions" because it can be burned without emissions.

[0009] In the passenger car sector, for example, hydrogen engines with external mixture formation (PFI = port fuel injection) are found, in which the fuel is thoroughly mixed with air in 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 virtually no role today, but compared to the PFI concept, they offer, among other things, higher efficiency, more stable combustion, and eliminate the risk of backfiring in the intake tract.

[0010] In direct-injection hydrogen engines, a distinction is typically still made regarding 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 shortened injection duration in a later compression phase at higher combustion chamber pressures, resulting in increased efficiency and improved combustion stability. However, overall efficiency decreases if compression of the hydrogen is required beforehand.

[0011] If the hydrogen is produced 100% from renewable energy sources, hydrogen combustion engines can operate virtually climate-neutrally. In addition, there are numerous other advantages:

[0012] • Use of known technologies with a high level of maturity and existing production facilities

[0013] • unlimited availability of hydrogen through electrolysis of water

[0014] • Use of the existing petrol station system possible (after appropriate conversion) with fast refueling times

[0015] • (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)

[0016] • significantly lower requirements for hydrogen purity compared to fuel cell drives

[0017] • 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 need 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 high mass-specific energy density); see Table 1

[0018] Provision of a consequently high volume flow during the injection of 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

[0019] 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 on mechanical stops in gas injectors compared to injectors with liquid fuels due to low damping effect during gas compression

[0020] Material resistance to hydrogen is necessary due to the risk of hydrogen embrittlement in mechanically stressed / pressurized components (reduced strength) or due to chemical reaction of hydrogen with oxygen present in the copper coil of the actuator (hydrogen disease of copper). Mixture preparation in the combustion chamber / influence of the injection jet / ignition behavior with very small injection quantities. 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).

[0021] Table 1 : Mass and volume specific calorific value of diesel and hydrogen

[0022] 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 pronounced bouncing, which occurs with gas injectors compared to injectors using liquid fuels, is addressed. Liquid fuels inherently have a damping or lubricating effect, so that an element surrounded by the fuel is dampened in its movement and experiences less wear when sliding along another element.

[0023] The present invention succeeds in solving or mitigating at least one of the above problems. For this purpose, an injector is to be provided which has all the features of independent claim 1. Advantageous embodiments of the present invention can be found in the subclaims following thereto. The present invention relates to an injector for injecting fuel, preferably for injecting a gaseous fuel, in particular hydrogen, which injector comprises 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 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 valve, in particular a solenoid valve, which is designedto transfer the armature element from a closing to a releasing state of the throttle and vice versa, and comprises an armature counterpart which is arranged on the side of the armature element opposite the throttle, wherein in a state of the armature element closing the throttle, an axially extending gap is formed between the armature counterpart and the armature element, both the armature element and the armature counterpart have an axially extending through-channel for conducting fuel, and a spring element arranged in the through-channel of the armature element and in the through-channel of the armature counterpart is provided to force the armature counterpart and the armature element apart and to press the armature element into a state closing the throttle. The injector is characterized in that a sleeve, the so-called armature sleeve, is arranged in the through-channel of the armature element.and / or a sleeve, the so-called pole core sleeve, is arranged in the through-channel of the armature counterpart, wherein the at least one sleeve is arranged in its through-channel such that it protrudes in the axial direction relative to the component receiving it and projects into the gap.

[0024] The sleeve's protrusion into the gap between the armature element and its counterpart ensures that, even when the injector is open and the armature element has been moved toward the counterpart due to the active valve, a residual air gap remains between the armature element and the counterpart, as the armature element abuts against the protruding portion of the sleeve. It is no longer necessary to adjust the residual air gap using foils or shims arranged between the facing surfaces of the armature element and the counterpart, as the protruding portion of the sleeve ensures the desired residual air gap.

[0025] It is clear to the person skilled in the art that the residual air gap can be generated both by a sleeve inserted into the armature element and by a sleeve inserted into the armature counterpart, wherein the invention also encompasses the case that a respective sleeve is provided in both the armature element and the armature counterpart, at least one of which protrudes from the component receiving it (i.e. armature element or armature counterpart) in the direction of the gap.

[0026] The provision of a sleeve arranged in the through-channel of the anchor element or anchor counterpart thus enables the creation of a residual air gap, in which the work steps typically used for this purpose for dimensioning and applying corresponding foils or shims to the mutually facing end faces of the anchor element and anchor counterpart no longer have to be carried out.

[0027] The precise adjustment of the residual air gap serves to influence the magnetic characteristic curve and thus characterizes the properties when opening or closing the injector.

[0028] In a fuel injector with a magnetic valve, the magnetic characteristic plays a relevant role in the function of the valve itself. The magnetic valve operates on the basis of electromagnetism, and the magnetic characteristic helps to understand how the magnetic field varies depending on the applied current.

[0029] The magnetic characteristic describes how the magnetic field (the magnetic flux density B) in a material changes depending on the applied magnetic field strength H. It indicates how much magnetism the material "conducts" or transmits when a specific magnetic field is applied.

[0030] In practice, the solenoid valve is controlled by a current that generates a strong magnetic field. This field strength attracts a magnetic metal core (the armature or armature element) toward its counterpart, causing the valve to open or close. The magnetic characteristic curve can provide information about how strong the current must be to achieve a specific movement of the armature element (and thus a specific valve position).

[0031] According to the invention, the sleeve can be secured in the through-channel for conducting fuel, in particular a gaseous fuel, by press fitting, clearance fitting, or friction welding in the armature counterpart or the armature element. Typically, the through-channel has a stepped cross-sectional widening or reduction to provide a recess for attaching the sleeve, thus securing it in the axial direction of the injector.

[0032] According to an advantageous modification of the present invention, it can be provided that the at least one sleeve has an inwardly projecting projection at its end remote from the gap in order to enable the spring element to be attached there.

[0033] This makes the typically used stop disc for the needle spring obsolete, since this function is taken over by the radially inwardly extending collars of the sleeve.

[0034] Furthermore, according to an advantageous embodiment of the present invention, the at least one sleeve can have an inner diameter, at least in sections, to guide and align the spring element, preferably a coil spring. The inner diameter of the sleeve can be adapted to or correspond to an outer circumference of a coil spring, so that the coil spring is guided by insertion into the sleeve and arranged and fixed in a predetermined position.

[0035] According to an advantageous modification of the present invention, the at least one sleeve can have a section in the axial direction that has a reduced wall thickness, so that damping occurs when an axial force compressing the sleeve acts. It can be provided that - viewed in the axial direction - the section with a reduced wall thickness is surrounded by sections with a comparatively increased wall thickness. A section with a regular (or thicker) wall thickness is thus followed by a section with a reduced wall thickness, before another section with a thicker wall thickness follows.

[0036] The reduced wall thickness ensures that when an axial force acts on the sleeve, it is compressed and acts as a spring element. This reduces unwanted needle bounce and thus improves the accuracy of the dispensed fuel quantity.

[0037] According to an optional modification of the present invention, it can be provided that the at least one sleeve is fixedly arranged in the component that receives it. Thus, it can be provided that the armature sleeve is fixedly arranged in the armature element. It can also be provided that the pole core sleeve is fixedly arranged in the armature counterpart.

[0038] For example, it can be provided that the sleeve is fastened in the element receiving it (anchor element or anchor counterpart) by means of a press fit, friction welding or the like.

[0039] According to a further development of the present invention, it can be provided that the at least one sleeve is arranged so as to be movable in the axial direction in the component receiving it, wherein a sleeve spring is preferably arranged at an end of the sleeve remote from the gap in order to urge the sleeve towards the gap. Thus, even when the injector is closed, in which the armature element closes the throttle with its needle, the gap formed between the armature element and the armature counterpart is overcome by the sleeve which is movable in the axial direction. At the end of the sleeve which is movable in the axial direction and is opposite the gap, a sleeve spring can then be provided which is compressed when the injector is opened and there is a resulting reduction in the gap between the armature counterpart and the armature element. Since, with such a configuration, the fuel is guided through the respective through-channels of the armature sleeve orSince the pole core sleeve has no possibility of penetrating radially outwards into the residual air gap that remains when the injector is open, this results in improved flow behavior with less turbulence.

[0040] Thus, the at least one sleeve that is movable in the axial direction ensures that, regardless of the state of the injector (open, closed or transition between open and closed), the fuel is guided without the formation of vortices between the armature counterpart and the armature element, which allows a more precise metering of the fuel to be delivered.

[0041] The axially movable sleeve can be guided by a support sleeve that partially extends into the passage of the movable sleeve. This support sleeve is fixedly mounted in the injector and has a corresponding recess for the sleeve spring to be inserted. To easily vary the spring force that pushes the axially movable sleeve toward the gap between the armature element and the armature counterpart, an adjusting disc can be provided that defines the tension of the sleeve spring relative to the movable sleeve.

[0042] Furthermore, according to an advantageous modification of the present invention, it can be provided that the sleeve protrudes so far from the component receiving it (anchor element or anchor counterpart) that it penetrates into the through-channel of the other component provided with the through-channel (anchor counterpart or anchor element), preferably in order to provide guidance during a movement of the anchor in the axial direction, wherein preferably the outer diameter of the section of the sleeve protruding into the other component is matched to the inner diameter of the through-channel of the other component (e.g. corresponds to this) in order to allow a sliding movement of the other component relative to the penetrating sleeve section.

[0043] For example, a residual air gap can be adjusted by a sleeve projecting on one side, which overcomes the gap between the armature element and its counterpart. Furthermore, the precise axial position of the stop on the projecting sleeve influences the magnetic characteristic during an opening process, allowing the injector's opening characteristics to be advantageously adjusted.

[0044] Furthermore, the overhang of the sleeve can be used to guide the component into which the sleeve penetrates with its overhang. For example, a pole core sleeve can protrude from the armature counterpart in such a way that its overhang dips into the armature element. If the area of ​​the armature element is matched to the dimensions of the overhang of the pole core sleeve penetrating it, this guides the armature element, which promotes a particularly reliable and low-maintenance implementation of the injector. Finally, the further guidance of the armature element further reduces the likelihood of undesired tilting. It will be clear to those skilled in the art that the armature sleeve can of course also penetrate into the armature counterpart, as this achieves the same advantages.

[0045] Furthermore, according to an optional development of the present invention, it can be provided that a non-magnetic or diamagnetic element is arranged between the end of the sleeve facing away from the gap and the component receiving the sleeve in order to interrupt or specifically redirect a magnetic flux, wherein the non-magnetic or diamagnetic element is a soft-elastic element, for example an elastomer, an amorphous metal and / or a metallic glass. As a rule, this non-magnetic or diamagnetic element has the shape of an annular disc, so that the fuel to be dispensed by the injector can be guided through its inner recess. Furthermore, this element can also be used to define the fine positioning of the sleeve in the element receiving it with respect to the axial direction.

[0046] According to a further advantageous modification of the present invention, it can be provided that the mutually facing end faces of the anchor element and the anchor counterpart have a mutually corresponding design, but are not smooth, wherein preferably the end face of the anchor element and the anchor counterpart have a step rising in the axial direction.

[0047] By providing two correspondingly designed end faces of the armature element and armature counterpart, which, however, are not located in the same plane, the magnetic characteristic can be specifically influenced. For example, with stepped end faces, where the step rises in the axial direction, a residual air gap can be created in two different planes. This serves to specifically influence the magnetic characteristic.

[0048] Furthermore, according to the present invention, it can be provided that on the outer circumference of the at least one sleeve, a radial gap extending in the axial direction is provided to the component receiving it in order to reduce or completely prevent a flow of magnetic field lines through the sleeve, preferably wherein the radial gap extends in the axial direction from the end facing the gap.

[0049] This gap or the radial gap between the outer circumference of the sleeve and the component receiving the sleeve (armature element or armature counterpart) also serves for the targeted control of magnetic field lines, which do not pass through the sleeve or only pass to a very limited extent if the gap is present.

[0050] According to a further advantageous modification of the present invention, it can be provided that a sleeve, the so-called armature sleeve, is arranged both in the through-channel of the armature element and a sleeve, the so-called pole core sleeve, is arranged in the through-channel of the armature counterpart, wherein each of the two sleeves protrudes from the respective component receiving it in the direction of the gap.

[0051] The design allows both the pole core sleeve and the armature sleeve to protrude from the respective component toward the gap. When the injector is closed and the armature element and needle are lifted from the throttle, they together define the residual air gap between the armature element and the armature counterpart. Another advantage is that only the two sleeves are in contact, which allows both the armature element and the armature counterpart to be constructed from materials that require less resistance to the constant impact on each other.

[0052] Furthermore, according to a further modification of the invention, it can be provided that when an armature sleeve and a pole core sleeve are present, the two sleeves are arranged relative to one another in their respective through-channel such that the mutually facing end surfaces of the two sleeves contact one another when the injector is in the open state.

[0053] It can preferably be provided that if an armature sleeve and a pole core sleeve are present, the outer diameter of the two sleeves is the same or different.

[0054] The invention further comprises an injector according to one of the preceding aspects, wherein the armature element is constructed in several parts and has a lower part facing the throttle and an upper part arranged between the lower part and the armature counterpart, the upper part being movable in the axial direction relative to a sleeve inserted into the lower part, the sleeve, when closed, protrudes from the lower part in the axial direction and projects beyond the upper part of the multi-part armature element, and the sleeve has, on the side facing away from the throttle, a radially extending projection which corresponds to a corresponding recess in the upper part of the armature element, so that when the upper part is moved towards the armature counterpart, the sleeve and the lower part of the armature element connected thereto are moved towards the armature counterpart according to the principle of a hammer armature, wherein an armature spring is preferably provided,which is designed to push the upper part of the armature element towards the throttle.,

[0055] The invention further relates to an internal combustion engine with a fuel injection, in particular with a gas direct injection, in particular with a hydrogen direct injection, comprising an injector according to one of the previously discussed aspects.

[0056] Further features, details, and advantages of the invention will become apparent from the following description of the figures. These show:

[0057] Fig. 1A: a schematic sectional view of a prior art injector in a closed state,

[0058] Fig. 1 B: a schematic sectional view of an injector according to the prior art in an open state,

[0059] Fig. 2: a schematic sectional view of an injector according to the invention with a sleeve projecting into the gap, Fig. 3: a schematic sectional view of a further embodiment of the injector according to the invention with two sleeves arranged opposite one another, each projecting into the gap,

[0060] Fig. 4: a schematic sectional view of a further embodiment of the injector according to the invention with a sleeve, the projection of which penetrates into the opposite component,

[0061] Fig. 5: a schematic sectional view of a further embodiment of the injector according to the invention with a sleeve, the projection of which penetrates into the opposite component and serves there as a guide,

[0062] Fig. 6: a schematic sectional view of a further embodiment of the injector according to the invention with a sleeve having a cross-sectional reduction to create a damping function,

[0063] Fig. 7: a schematic sectional view of a further embodiment of the injector according to the invention with a sleeve which rests on an insulating disc on its side facing away from the air gap,

[0064] Fig. 8: a schematic sectional view of a further embodiment of the injector according to the invention, wherein both sleeves arranged opposite one another have an inwardly projecting projection at their respective ends facing away from the air gap,

[0065] Fig. 9A: a schematic sectional view of a further embodiment of the injector according to the invention in a closed state, in which the mutually facing end faces of the anchor element and the anchor counterpart are not planar, Fig. 9B: a schematic sectional view of a further embodiment of the injector according to the invention in an open state, in which the mutually facing end faces of the anchor element and the anchor counterpart are not planar,

[0066] Fig. 10: a schematic sectional view of a further embodiment of the injector according to the invention with a sleeve having a cross-sectional reduction to create a damping function,

[0067] Fig. 11: a schematic sectional view of a further embodiment of the injector according to the invention, wherein a radially extending gap is provided between the sleeve and the component receiving the sleeve,

[0068] Fig. 12A: a schematic sectional view of another embodiment of the injector according to the invention in an open state, wherein the armature is designed in the form of a hammer armature,

[0069] Fig. 12B: a schematic sectional view of another embodiment of the injector according to the invention in a closed state, wherein the armature is designed in the form of a hammer armature,

[0070] Fig. 13: a schematic sectional view of a further embodiment of the injector according to the invention with a sleeve movable in the axial direction, and

[0071] Fig. 14: A schematic sectional view of another embodiment of the injector according to the invention with a sleeve movable in the axial direction. The following detailed description of Fig. 1 is explained using an injector for injecting a gaseous fuel, although it will be clear to those skilled in the art that the invention also encompasses an injector for injecting another fuel, for example, a liquid fuel.

[0072] Fig. 1A 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 (not shown) is provided for introducing a fuel into the injector 1. First, the fuel or another flammable fluid (for example hydrogen) is fed through a bore in a cover 12, which runs approximately centrally in the injector housing 2 and can be screwed to the housing 2. The fuel thus introduced is then fed through a through-channel of an armature counterpart 7 and a through-channel of the armature 3 to the end of the valve needle 4 remote from the connection side. The needle 4 and / or armature 3 can be designed in one or more parts.Needle 4 and armature 3 are preferably firmly connected to one another, e.g., by force, or are designed as a single piece. However, a design with a freewheel between needle 4 and armature 3, so that armature 3 only comes into contact with needle 4 after a certain run-up distance and carries it along by force transmission through contact, is also conceivable and also encompassed by the invention.

[0073] Depending on the position of the armature element 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. 1A, the throttle 5 is closed by the pressing of the valve needle 4 against the valve plate 15, since the end face of the valve needle 4 covers the opening contour of the at least one throttle 5. If the at least one throttle 5 is closed by the end face of the valve needle 4, the fluid flow of the fuel is stopped at this point in the injector 1, and there is no downstream flow of fuel beyond the valve plate 15. The injector is therefore in a closed state.

[0074] If, however, the throttle 5 is released, which is implemented by the armature element 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 at least one throttle 5 on the side of the valve plate 15 spaced apart from the armature 3. As a result, the pressurized fuel flows out of the injector 1 through the injection pipe 22. After flowing through the injection pipe 22, the fuel delivered by the injector 1 is then typically located outside the injector 1 in a combustion chamber. In addition, a compression of the fuel usually takes place in the combustion chamber, where the fuel is then ignited or is ignited.

[0075] 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 by a valve, which in the present illustration in Fig. 1A is a solenoid valve. 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. The resulting lifting of the valve needle 4 releases the throttle 5 in the valve plate 15, allowing fuel to flow through the valve plate 15.

[0076] For precise guidance of the valve needle 4 along the longitudinal axis X of the injector 1 (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. Since the valve needle 4 is solid in the present embodiment, at least one through-channel is provided in the valve needle guide 19 for conducting fuel, through which channel fuel can flow to the fuel outlet. The valve needle guide is fixedly arranged on the housing 2 of the injector 1.

[0077] Furthermore, 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.

[0078] To improve the magnetic flux 24 when the valve 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. A similar situation applies to the housing component directly surrounding the armature element 3 and the armature counterpart 7, which is preferably also made of a magnetizable material. It can be advantageous if the pole tube, which is a component of the injector 1, is also made of iron or another ferromagnetic material. The same also applies to the armature counterpart 7, which is advantageously also made of a magnetizable material.

[0079] A visual representation of the magnetic field lines 24 is illustrated by the dotted, closed line that runs around the coil. The magnetic force pulls the armature 3 (together with the valve needle 4) toward the armature counterpart 7, thus lifting it from the valve plate 15 or from the at least one throttle 5 that penetrates the valve plate 15, resulting in an inflow of fuel toward the injection pipe 23, from where the fuel can be introduced into the combustion chamber.

[0080] In order to guide the magnetic flux lines 24 preferably through the axial working air gap 18 between the armature 3 and the armature counterpart 7 and thus significantly increase the magnetic force between these components, it is advantageous to provide a recess in the housing 2 at the level of the working air gap 18 or to introduce a non-magnetic or only weakly magnetizable one- or multi-part intermediate ring over the entire or partial thickness of the housing 2, e.g. by means of a welded connection. This is referred to below as a bypass 20. The bypass therefore ensures that the magnetic flux lines do not run through the housing 2 or only run through it to a very small extent, where they have no effect on the force of attraction between the armature element 3 and the armature counterpart 7.

[0081] The armature counterpart 7 is fixedly arranged in the injector's longitudinal direction and has no play. Thus, the armature counterpart 7 is secured between an adjusting element 8, which allows fine adjustment in the axial direction and can be disc-shaped, and the cover 12. The adjusting element 8 is typically made of metal and serves to precisely specify the position of the armature counterpart 7 in relation to the injector's longitudinal direction of the injector 1. Thus, during the manufacture of the injector 1, depending on the tolerances of the injector components, a subsequently selected adjusting element 19 can be installed so that the distance in the injector's longitudinal direction from the armature 3 to the armature counterpart 7 corresponds to a predetermined value when the valve is in the closed position.

[0082] As described above, however, the problem arises that during the 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 liquid fuel is lacking to reduce the bouncing of the armature 3 against the armature counterpart 7. The disadvantage of this bouncing process is that the closing process is not interrupted in a precisely predictable manner; instead, the bouncing causes repeated opening and closing.

[0083] Fig. 1B shows the injector illustrated in Fig. 1A in an open state, comparing a closed and an open injector valve. A fuel path through the injector 1 during fuel injection can be seen, indicated by the arrows. In Fig. 1A, the injector needle 4 is placed on the throttle 5 of the valve plate 15 in such a way that no fluidic connection can arise from the inlet of the injector 1 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, is the throttle 5 opened, creating a fuel path that leads to the outlet.

[0084] If a voltage signal is applied by a control device via electrical contacts to the actuator's coil 17, the current in the electrical circuit rises to a defined final level. The current-carrying coil 17 induces a magnetic field in the actuator, whose magnetic field lines spread toroidally around the coil 17. The magnetic field creates a magnetic force in the (residual) air gap 18 between the armature 3 and its counterpart armature 7, causing the armature 3 to be attracted to its counterpart armature 7 as soon as the magnetic force exceeds the closing force (the sum of the preload force of the needle spring 14 and the compressive forces on the needle 4 and the armature 3). The residual air gap is adjusted using foils or shims.

[0085] The armature 3 is—as shown—advantageously fixed to the valve needle 4 or is a one-piece armature-valve needle component, 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, allowing fuel to flow from the needle chamber into the injection chamber and finally into the combustion chamber. When the armature 3 hits the upper stop, a relatively strong bounce typically occurs, which negatively impacts the controllability of the fuel injection quantity.

[0086] To end the injection process, the power supply is terminated by a control unit, so that the current through coil 17 is reduced to zero. This also dissipates the magnetic field. As soon as the magnetic force is sufficiently low, needle 4 and armature 3 begin to close, preferably uniformly. If the end face of needle 4 closes at least one throttle 5 in valve plate 15 again, the connection between the needle chamber and the injection chamber is severed, interrupting the fuel flow and ending fuel injection. This can also lead to bouncing, which negatively impacts the controllability of the fuel injection quantity.

[0087] A variety of embodiments of the present invention are described below with reference to the accompanying figures. Typically, specific features are described for either the pole core sleeve 9 or the armature sleeve 8, although it will be clear to those skilled in the art that the described properties can be present in both the pole core sleeve 9 and / or the armature sleeve 8. A separate description of the other sleeve is omitted for the sake of clarity.

[0088] Fig. 2 shows an injector 1 according to the invention in which a sleeve 8, 9 is provided both in the anchor element 3 and in the anchor counterpart 7.

[0089] It can be provided that one of the two sleeves 8, 9 projects out of the component receiving it in the direction of the gap 18. In the present case, this is the pole core sleeve 9, which has a certain projection from the armature counter element 7 in the direction of the gap 18. Furthermore, the pole core sleeve 9 has a radially inwardly directed recess at its end opposite the gap 18, which serves to provide the needle spring 14 with an attachment point 16. At the same time, the valve spring 14 can also be fixed and aligned through clever dimensioning of the sleeve 9, this being achieved, for example, by a somewhat thicker diameter of the pole core sleeve 9, which creates a certain clamping and guiding effect for the needle spring 14 and thus fixes it, for example, perpendicular to the axial direction.

[0090] In addition, in Fig. 2, the armature element 3 is also provided with a sleeve, the armature sleeve 8, which, just like the pole core sleeve 9, is received by a press fit or clearance fit in a recess of the component receiving the sleeve 8, 9 (armature element 3 or armature counterpart 7). In contrast to the pole core sleeve 9, the armature sleeve 8 in this case does not have an inwardly projecting projection, but rather has the basic shape of a cylindrical surface or a ring. The armature sleeve 8 and the pole core sleeve 9 are received in their respective component (armature element 3 or armature counterpart 7) in such a way that their respective mutually facing end surfaces contact one another when the injector is opened and the armature 3 moves towards the armature counterpart 7. The projection of the pole core sleeve 9 ensures that a defined residual air gap 18 remains and that the mutually facing end surfaces of the armature element 3 and armature counterpart 7 do not touch one another.As shown, the thickness and / or outer diameter of the two sleeves 8, 9 can also be different, although advantageously, when the injector is open, the end face of the protruding sleeve only touches the end face of the other sleeve. In addition to the advantage of defining a predetermined residual air gap when the injector is open, a material pairing of the sleeves can also be selected that is designed for frequent collisions.

[0091] Thus, the armature sleeve 8 or the pole core sleeve 9 can consist of a magnetic or non-magnetic, hardened or high-strength steel or comprise such a steel.

[0092] It will be clear to those skilled in the art that, although Fig. 2 only shows the variant in which the pole core sleeve 9 has a projection, the invention also encompasses the possibility of the armature sleeve 8 having a projection instead of the pole core sleeve 9. The advantages described above can also be achieved in this way.

[0093] Fig. 3 shows a sectional view of the implementation according to the invention, in which both the armature sleeve 8 and the pole core sleeve 9 have a projection that each penetrates the gap 18. When the injector is open, the residual air gap 18, i.e. the distance from the armature element 3 to the armature counterpart 7, is therefore no longer defined solely by a projection 27 of one of the two sleeves 8, 9, but rather by the combined projection of the two sleeves (armature sleeve 8 and pole core sleeve 9). The exact axial position of the air gap 18 serves to influence the magnetic characteristic curve and therefore affects the opening and closing behavior of the injector 1. Fig. 4 shows a sectional view of a further embodiment of the present invention, in which the projection of the pole core sleeve 9 preferably protrudes so far relative to the armature counterpart 7, even when the injector 1 is closed, that the latter is circumferentially surrounded by the armature element 3.In other words, the projection 27 of the pole core sleeve 9 engages the armature element 3. For example, this can be achieved by designing the armature sleeve 8, which is somewhat wider in thickness, in such a way that it ends before reaching the gap 18. The space thus left free is occupied by the pole core sleeve 9, which overcomes the air gap 18.

[0094] Fig. 5 shows a further development of the present invention, wherein the projection 27 of the pole core sleeve 9 is used for a guide 23 of the armature element 3. The inner diameter of the area that accommodates the projection 27 of the pole core sleeve 9 was adapted so that a guiding effect is created when the armature 3 moves in the axial direction. The armature element is therefore guided not only by the needle guide 19, but also by the projection 27 of the pole core sleeve 9, so that tilting when the armature 3 moves is significantly less likely.

[0095] Fig. 6 shows the embodiment according to Fig. 5 described above, which has been supplemented by a further damping function. It can be seen that the pole core sleeve 9 has an area of ​​reduced thickness 26, which has a damping effect when an axially directed force is applied. If the armature element 3 is now moved from the closed to the open position, not only the needle spring 14 counteracts this movement, but also the pole core sleeve 9 itself. The reduction in thickness, which is partial or continuous in the circumferential direction, thus means that the sleeve can be compressed in the axial direction, so that the armature element 3 moving towards the armature counterpart 7 is braked in its movement. Viewed in the axial direction, both in front of and behind the area with the reduced thickness 26, the thickness of the material of the pole core sleeve 9 is normal again, i.e. increased compared to the area with the reduced thickness 26.

[0096] Fig. 7 describes a further embodiment of the present invention, in which a non-magnetic and / or diamagnetic element 28 is arranged between the end region of a sleeve facing away from the air gap 18, in this case the pole core sleeve 9, and the armature counterpart 7. This serves to interrupt or deliberately redirect the magnetic flux that occurs when an active solenoid valve is active. In conjunction with the bypass 20, this ensures that the magnetic flux is effectively utilized to generate the maximum magnetic force between the armature element 3 and the armature counterpart 7.

[0097] Furthermore, it can be provided that the element 28 is a soft-elastic element, for example, consisting of or comprising an elastomer, an amorphous metal, and / or a metallic glass. As shown, the element 28 can have the shape of a disk, so that one could also refer to it as an insulating disk.

[0098] Fig. 8 shows an embodiment of the present invention in longitudinal section, in which both the armature sleeve 8 and the pole core sleeve 9 have, at their end remote from the air gap 18, a radially inwardly projecting recess for supporting and guiding the needle spring 14. In addition, an adjusting disk 29 is provided, which is arranged in the interior of the armature sleeve 8 and is held in place in the axial direction by the recess. This adjusting disk 29 serves to finely adjust the tension of the needle spring 14, whereby the force urging the armature element 3 towards the closed position increases with increasing thickness of the adjusting disk 29. The reference numeral 16 designates the supporting and guiding of the needle spring 14, which now occurs at both ends of the needle spring 14 due to the similar design of the armature sleeve 8 and the pole core sleeve 9. Fig.Figure 9A shows a further embodiment of the present invention in which the mutually facing end faces of armature element 3 and armature counterpart 7 are not planar. Although the mutually facing end faces are still shaped to correspond to one another, in Figure 9A they have a step arranged in the axial direction, which serves to specifically influence the magnetic characteristic. Furthermore, this step also creates a guide to enable reliable movement of armature element 3 in the axial direction. The residual air gap 18, which remains between the two end faces when injector 1 is in its open position, is also created in this implementation by a projection of a sleeve, here the pole core sleeve 9.

[0099] In contrast to Fig. 9A, Fig. 9B shows the open position of the injector, wherein it can be clearly seen that the stop formed by the projection of the pole core sleeve 9 continues to form a residual air gap 18 of the mutually corresponding step-like end faces 30.

[0100] Fig. 10 shows a further embodiment of the present invention, in which the sleeves provided with respective radially inwardly directed projections can also have a thickness reduction 26, which causes a certain damping effect when the anchor element 3 moves towards each other relative to the anchor counterpart 7.

[0101] Fig. 11 shows a further embodiment of the injector 1 according to the invention in a sectional view, in which the pole core sleeve 9, in its outer circumferential region, does not fully contact the component receiving it, in this case the armature counterpart 7. Rather, there is a radially extending gap 32 between the outer circumferential side of the pole core sleeve 9 and the armature counterpart 7 receiving the pole core sleeve 9. This radial gap 32 extends as far as the air gap 18, but does not run over the entire axial length of the pole core sleeve 9. In the present example, the axial length of this gap 32 exceeds approximately half the total length of the pole core sleeve (seen in the axial direction). Accordingly, it can be advantageous if the length of the gap 32, seen in the axial direction, is at least half the length of the pole core sleeve 9, seen in the axial direction. This radial gap between the sleeve and the component receiving the sleeve (in Fig.11 Armature counterpart 7) ensures that the magnetic field lines do not pass through the sleeve or only to a small extent.

[0102] Fig. 12A shows a further embodiment of the present invention, in which the anchor element 3 is designed in several parts and has a lower anchor 33 and an upper anchor 34. The lower anchor 33 and the upper anchor 34 can be moved independently of one another in the axial direction. The anchor sleeve 8 has, at its end facing the gap 18, a radially outwardly projecting projection 35, which corresponds to a corresponding recess of the upper anchor 34, so that when the upper anchor is moved, the projection 35 of the anchor sleeve 8 serves as a driver.

[0103] In the closed position of the injector 1 shown in Figure 12A, it can be seen that a gap in the axial direction is provided between the upper armature 34 and the sleeve projection 35, which must only be overcome upon a corresponding axial movement of the upper armature 34. When the coil 17 is energized, the upper armature 34, after overcoming the gap, strikes the collar of the sleeve projection 35 of the armature sleeve 8 and thus reduces the magnetic force required to open the valve due to the kinetic energy absorbed during the starting movement.

[0104] This principle is also called a hammer armature, since the upper armature strikes the sleeve projection 35 like a hammer and, via the connection between the armature sleeve 8 and the lower armature 33, abruptly lifts the needle 4 from the throttle 5. An armature return spring 36 is also provided to push back the upper armature 34, which serves to urge the upper armature 34 toward the throttle 5 so that, when the injector 1 is closed, a pronounced gap in the axial direction is again established between the upper armature 34 and the sleeve projection 35.

[0105] Fig. 12B shows an open state of the injector 1, which has already been described in Figure 12A. It can now be seen that the valve needle 4 has been lifted off the throttle 5, so that fuel can flow out of the injector 1. The lifting of the valve needle 4, which is connected to the lower armature 33, was caused by the upper armature 34 engaging the sleeve projection 35 of the armature sleeve 8. The previously existing air gap 37 between the upper armature 34 and the sleeve projection 35 is now closed. The armature return spring 36 is in a compressed state and, after the magnetic force which urges the upper armature towards the armature counterpart 7 has subsided, causes the upper armature 34 to be urged towards the lower armature 33 until it makes contact with it and then urges it further towards the throttle 5. This ultimately leads to the throttle 5 closing and the fuel flow being interrupted.

[0106] Fig. 13 shows a further embodiment of the present invention, in which the pole core sleeve 9 is a movable sleeve 39 that can be moved back and forth in the axial direction. The urging of the armature element 3 against the throttle 5 when the injector 1 is closed therefore does not occur exclusively due to the force applied by the needle spring 14, but is supported by the movable pole core sleeve 39, which is urged toward the armature element 3 by the sleeve spring 38. The movable sleeve 39 can also be referred to as a sliding sleeve and completely overcomes the air gap 18 existing between the armature element 3 and the armature counterpart 7, which forms when the injector 1 is closed.At the end of the movable sleeve 39 facing away from the armature element 3, the armature counterpart has a stop 40 which ensures that when the injector 1 is opened, the air gap 18 existing between the armature element 3 and the armature counterpart 7 is not completely closed, but remains in a reduced form due to a remaining projection of the sleeve part of the movable sleeve 39 protruding from the armature counterpart 7. This ensures that when the injector is open, the armature element 3 and the armature counterpart 7 do not rest against one another on their facing surfaces, since a projection of the movable sleeve 39 remains due to the stop 40. The stop 40 can be finely adjusted in its axial position by inserting an adjusting disk 29 in order to precisely set the projection of the movable sleeve 39 protruding from the armature counterpart 7, even when the spring is compressed.

[0107] Fig. 14 shows a further development of the embodiment of the injector 1 described in Fig. 13, wherein the armature counterpart 7 is formed in several parts.

[0108] Thus, the part used for attaching the movable sleeve 39 can be designed separately from another part of the armature counterpart 7. This section, designated by reference numeral 41, can represent a fixed secondary sleeve, which, in conjunction with the other part of the armature counterpart 7, forms a receptacle for the adjusting disc 29 and the sleeve spring 38.

[0109]

[0110] 1 injector

[0111] 2 injector housings

[0112] 3 Anchor element / anchor

[0113] 4 valve needle

[0114] 5 Throttle

[0115] 6 Press or loose fit

[0116] 7 Anchor counterpart

[0117] 8 anchor sleeve

[0118] 9 Pole core sleeve

[0119] 10 Adjusting / stop disc needle spring

[0120] 11 Adjusting / stop disc needle spring

[0121] 12 lids

[0122] 13 Adjustment element

[0123] 14 needle spring

[0124] 15 Valve plate

[0125] 16 Bearing / guide of the needle spring

[0126] 17 coil

[0127] 18 Air gap

[0128] 19 Needle guide

[0129] 20 Bypass element

[0130] 21 Iron return / housing section

[0131] 22 Injection pipe

[0132] 23 upper anchor and needle guide

[0133] 24 Course of magnetic field lines

[0134] 25 Guide element

[0135] 26 Thickness reduction for damper function

[0136] 27 Sleeve overhang

[0137] 28 non-magnetic or diamagnetic element

[0138] 29 Adjusting disc

[0139] 30 step-like front surface

[0140] 31 stop 32 radial gap

[0141] 33 lower anchor

[0142] 34 upper anchor

[0143] 35 Sleeve projection 36 Armature return spring

[0144] 37 Air gap anchor - sleeve projection

[0145] 38 sleeve spring

[0146] 39 movable sleeve

[0147] 40 Sleeve stop 41 Fixed secondary sleeve

[0148] X Axial direction of the injector

Claims

Claims 1. 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 arranged in the injector housing so as to be movable along an axial direction of the injector and 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 valve, in particular a solenoid valve, designed to transfer the armature element from a closing to a releasing state of the throttle and vice versa, and an armature counterpart arranged on the side of the armature element opposite the throttle, wherein, in a state of the armature element in which the throttle is closed, a gap extending in the axial direction is formed between the armature counterpart and the armature element,both the armature element and the armature counterpart have a through-channel running in the axial direction for conducting fuel, and a spring element arranged in the through-channel of the armature element and in the through-channel of the armature counterpart is provided in order to, Armature counterpart and the armature element to be forced apart and the armature element to move into a state closing the throttle, characterized in that a sleeve, the so-called armature sleeve, is arranged in the through-channel of the armature element and / or a sleeve, the so-called pole core sleeve, is arranged in the through-channel of the armature counterpart, wherein the at least one sleeve is arranged in its through-channel such that it protrudes in the axial direction relative to the component receiving it and projects into the gap.

2. Injector according to the preceding claim, wherein the at least one sleeve has an inwardly projecting collar at its end remote from the gap to enable the spring element to be attached there.

3. Injector according to one of the preceding claims, wherein the at least one sleeve has at least in sections an inner diameter in order to guide and align the spring element, preferably a spiral spring.

4. Injector according to one of the preceding claims, wherein the at least one sleeve has a section in the axial direction which has a reduced wall thickness, so that damping occurs when an axial force compressing the sleeve acts.

5. Injector according to one of the preceding claims, wherein the at least one sleeve is fixedly arranged in the component receiving it.

6. Injector according to one of the preceding claims 1-4, wherein the at least one sleeve is arranged to be movable in the axial direction in the component receiving it, wherein a sleeve spring is preferably arranged at an end of the sleeve remote from the gap in order to urge the sleeve towards the gap.

7. Injector according to one of the preceding claims, wherein the sleeve projects so far from the component receiving it that it penetrates into the through-channel of the other component provided with the through-channel, preferably in order to provide guidance during a movement of the armature in the axial direction, wherein the outer diameter of the section of the sleeve projecting into the other component is preferably matched to the inner diameter of the through-channel of the other component in order to allow a sliding movement of the other component relative to the penetrating sleeve section.

8. Injector according to one of the preceding claims, wherein a non-magnetic or diamagnetic element is arranged between the end of the sleeve facing away from the gap and the component receiving the sleeve in order to interrupt or specifically redirect a magnetic flux, wherein the non-magnetic or diamagnetic element is a soft-elastic element, for example an elastomer, an amorphous metal and / or a metallic glass.

9. Injector according to one of the preceding claims, wherein the mutually facing end faces of the anchor element and the anchor counterpart have a mutually corresponding design, but are not smooth, wherein preferably the end face of the anchor element and the anchor counterpart have a step rising in the axial direction.

10. Injector according to one of the preceding claims, wherein on the outer circumference of the at least one sleeve there is a radial gap extending in the axial direction to the component receiving it in order to reduce or completely prevent a flow of magnetic field lines through the sleeve, preferably wherein the radial gap extends in the axial direction from the end facing the gap.

11. Injector according to one of the preceding claims, wherein a sleeve, the so-called anchor sleeve, is provided both in the passage of the anchor element and a sleeve, the so-called Pole core sleeve, wherein each of the two sleeves protrudes from the respective component receiving it in the direction of the gap.

12. Injector according to one of the preceding claims, wherein, when an armature sleeve and a pole core sleeve are present, the two sleeves are arranged relative to one another in their respective through-channels such that the mutually facing end surfaces of the two sleeves contact one another when the injector is in the open state.

13. Injector according to one of the preceding claims, wherein, when an armature sleeve and a pole core sleeve are present, the outer diameter of the two sleeves is the same or different.

14. Injector according to one of the preceding claims, wherein the armature element is constructed in several parts and has a lower part facing the throttle and an upper part arranged between the lower part and the armature counterpart, the upper part is movable in the axial direction relative to a sleeve inserted into the lower part, the sleeve, in a closed state, projects out of the lower part viewed in the axial direction and projects beyond the upper part of the multi-part armature element, and the sleeve has, on the side facing away from the throttle, a radially extending projection which corresponds to a corresponding recess of the upper part of the armature element, so that when the upper part is moved towards the armature counterpart, the sleeve and the lower part of the armature element connected thereto are moved towards the armature counterpart according to the principle of a hammer armature, wherein preferably an armature spring is provided which is designed toto push the upper part of the armature element towards the throttle.

15. Internal combustion engine with a fuel injection system, in particular with a gas direct injection system, in particular with a hydrogen direct injection system, comprising an injector according to one of the preceding claims.

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