DE102021133213A1 - Injector for injecting fuel - Google Patents

Abstract

The present invention relates to an injector for injecting fuel, preferably for blowing in a gaseous fuel, in particular hydrogen, which has a fuel supply line for introducing a gaseous fuel under high pressure, an active valve which can be actively switched and is designed to optionally have a flow connection to release or interrupt from the fuel supply line to an area downstream of the first side of the valve plate, in particular by releasing or closing at least one passage on a first side of a valve plate through the active valve, and comprising a passive valve, which is arranged downstream of the valve plate and through upstream and different pressure conditions present downstream of the passive valve can be switched passively into a closing or releasing state. The injector is characterized in that the passive valve has a tappet which is urged by magnetic force in the closing direction of the passive valve, and preferably wherein the at least one passage on a second side of the valve plate facing away from the first side can be closed or opened with the tappet.

Description

The present invention relates to an injector for injecting fuel, in particular for blowing in a gas, preferably for blowing in hydrogen directly. It can be provided that the injector is designed to inject fuel into a combustion chamber of an internal combustion engine.

In the course of ever more stringent emission limits and ambitious climate protection goals, the environmental requirements for internal combustion engines are constantly increasing. In the foreseeable future, the goal is low-emission or even zero-emission drive technologies that also meet the strictest emission limits and make a significant contribution to achieving climate protection goals. In the case of technologies that work with combustion, these goals can only be achieved if climate-neutral, regeneratively produced fuels are used that do not cause any emissions along the entire value chain (so-called "zero emissions" fuels).

With current conventional petrol, diesel and gas engines, the requirements for emission-free combustion - even when using so-called e-fuels, e.g. a synthetically produced OME fuel, for the production of which only regenerative energy is required - cannot be achieved, since the Emissions of harmful exhaust gases such as nitrogen oxides (NO _x ), unburned hydrocarbons (UHC) and soot cannot be completely reduced with today's technologies.

In principle, battery-powered drives meet the zero-emissions directive during operation and are v. a. on the rise in the passenger car sector. If, on the other hand, the entire value chain is considered, the production of (lithium) batteries is very expensive in terms of energy and problematic from an environmental point of view, since the mining of raw materials causes severe environmental damage and the mining of the raw materials required for the batteries cannot be carried out sustainably. In addition, with the power-to-weight ratio that can be achieved today, use in machines with a high (peak) power requirement is not possible.

Fuel cell-powered drives powered by regeneratively produced hydrogen meet the specified climate protection goals and are already in use to a very limited extent. However, this concept also has some disadvantages, e.g. a low peak power compared to today's diesel drives and low economic efficiency.

The focus has therefore shifted to hydrogen combustion engines, which represent a promising drive alternative. To date, however, these exist almost exclusively in very small numbers or as demonstrators with a low degree of maturity. Hydrogen produced by regenerative energies would meet all the requirements of "zero emissions" because it can be combusted without producing any emissions.

In the passenger car sector, for example, there are hydrogen engines with external mixture formation (PFI = port fuel injection), in which the fuel is sufficiently mixed with air before it enters 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 nowadays, but compared to the PFI concept they have higher efficiency, more stable combustion and elimination of the risk of backfire in the intake tract on.

In the case of direct-injection hydrogen engines, a distinction is typically made 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 reduced injection duration late in compression at higher combustion chamber pressures, resulting in increased efficiency and improved combustion stability. However, the overall efficiency drops if the hydrogen has to be compressed beforehand.

• • Verwendung bekannter Technologien mit hohem Reifegrad und bestehender Produktionsanlagen
• • unbegrenzte Verfügbarkeit des Wasserstoffs durch Elektrolyse von Wasser
• • Nutzung des bestehenden Tankstellensystems möglich (nach entsprechender Umrüstung) mit schnellen Tankzeiten
• • (fast) emissionsfreie Umwandlung des Wasserstoffs in der Verbrennung möglich, da CO2-neutral, nur minimale CO, UHC-, Partikel- und Ruß-Emissionen (lediglich verursacht durch Schmierstoffe im Zulaufsystem, unterhalb der Messgrenze) und nur minimale NOx-Emissionen durch geeignetes Verbrennungsverfahren (ggf. mit Abgasrückführung, SCR-Katalysator)
• • deutlich geringere Anforderung an Reinheit des Wasserstoffs im Vergleich zu Brennstoffzellen-Antrieben
• • kein Bedarf an Platin zur Herstellung wie bei Brennstoffzellen

If the hydrogen is obtained 100% from renewable energies, almost climate-neutral operation can be achieved with hydrogen combustion engines. In addition, there are numerous other advantages:

• • Use of well-known technologies with a high level of maturity and existing production facilities
• • unlimited availability of hydrogen through electrolysis of water
• • Use of the existing filling station system possible (after appropriate conversion) with fast refueling times
• • (Almost) emission-free conversion of hydrogen during combustion possible, as CO2-neutral, only minimal CO, UHC, particle and soot emissions (caused solely by lubricants in the intake system, below the measurement limit) and only minimal NOx emissions through Suitable combustion process (possibly with exhaust gas recirculation, SCR catalytic converter)
• • Significantly lower hydrogen purity requirements compared to fuel cell drives
• • no need for platinum for production as with fuel cells

• • geringes Molekulargewicht von Wasserstoff, dadurch eine geringe Dichte einhergehend mit einer geringen volumetrischen Energiedichte (bei hoher massenspezifischer Energiedichte); siehe Tabelle 1
• • Bereitstellung eines demzufolge hohen Volumenstroms bei der Einblasung von Wasserstoff
• • entsprechende Bereitstellung von großen Strömungsquerschnitten im Injektor und damit benötigter deutlich größerer Hübe des Aktuators als bei konventionellen Antriebsarten
• • einhergehende Entwicklung einer deutlich stärkeren Aktuatoreinheit bei gleichzeitig begrenztem Bauraum
• • Dichtheit des Gesamtsystems / Verhinderung von externen Leckagen, v. a. im Hinblick auf Sicherheitsaspekte (Brand- und Explosionsgefahr aufgrund aus dem System austretenden Wasserstoff)
• • erhöhte Verschleißgefahr an Führungen bewegter Bauteile aufgrund der praktisch nicht vorhandenen Schmierwirkung von Wasserstoff
• • deutlich stärkere Neigung bewegter Bauteile zum Prellen an mechanischen Anschlägen in Gasinjektoren im Vergleich zu Injektoren mit Flüssigkraftstoffen durch geringe Dämpfwirkung bei der Gaskompression
• • Materialbeständigkeit gegenüber Wasserstoff nötig im Hinblick auf die Gefahr einer Wasserstoffversprödung in mechanisch beanspruchten / druckbeaufschlagten Bauteilen (reduzierte Festigkeit) oder durch chemische Reaktion des Wasserstoffs mit in der Kupferspule des Aktuators vorhandenem Sauerstoff (Wasserstoffkrankheit des Kupfers)
• • Gemischaufbereitung im Brennraum / Beeinflussung des Einblasstrahls / Zündverhalten bei Kleinstmengeneinblasung

Tabelle 1: Massen- und volumenspezifischer Heizwert von Diesel und Wasserstoff Diesel Wasserstoff (bei 25 °C) Heizwert in MJ/kg 43.0 120.0 Heizwert in MJ/m³ 35'819 9.8 bei 1 bar 287.7 bei 30 bar 2464.4 bei 300 bar In addition to these numerous advantages compared to 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, resulting in a low density accompanied by a low volumetric energy density (with a high mass-specific energy density); see Table 1
• • Provision of a correspondingly high volume flow when blowing in hydrogen
• • Corresponding provision of large flow cross-sections in the injector and thus required significantly larger strokes of the actuator than with conventional types of drive
• • Associated development of a significantly stronger actuator unit with limited space at the same time
• • 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 the 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 the low damping effect during gas compression
• • Material resistance to hydrogen necessary with regard to the risk of hydrogen embrittlement in mechanically stressed / pressurized components (reduced strength) or due to chemical reaction of the hydrogen with oxygen present in the copper coil of the actuator (hydrogen disease of the copper)
• • Mixture preparation in the combustion chamber / influencing the injection jet / ignition behavior with injection of very small quantities

Table 1: Mass and volume specific calorific value of diesel and hydrogen Diesel Hydrogen (at 25 °C) Calorific value in MJ/kg 43.0 120.0 Calorific value in MJ/ ^m3 35'819 9.8 at 1 bar 287.7 at 30 bar 2464.4 at 300 bar

It is the object of the present invention to at least partially overcome or mitigate the disadvantages listed above. In particular, a fuel injector is to be created that enables reliable operation even under high thermal loads. In addition, it is advantageous if the injector takes up only a small installation space and/or has a small axial length and has few parts in its structure. It is also advantageous if the injector is reliably sealed against the pressure in the cylinder during its compression phase, since the high cylinder pressure would otherwise press the switchable valve into the open position. Furthermore, it is advantageous if rapid and stable opening is possible with the injector, in which case the flow is not throttled. At least some or all of the foregoing objectives are achieved with an injector for injecting fuel that includes all Having features of claim 1 achieved. Advantageous configurations of the injector are specified in the dependent claims.

An injector according to the invention for injecting fuel, preferably for blowing in a gaseous fuel, in particular hydrogen, comprises a fuel supply line for introducing a gaseous fuel under high pressure, an active valve which can be actively switched and is designed to optionally have a flow connection from the fuel supply line to an area downstream of the first side of the valve plate or to open, in particular by opening or closing at least one passage on a first side of a valve plate through the active valve, and a passive valve, which is arranged downstream of the valve plate and through upstream and downstream of the passive valve applied different pressure conditions can be switched passively into a closing or releasing state. The injector is characterized in that the passive valve has a tappet which is urged by magnetic force in the closing direction of the passive valve, and preferably wherein the at least one passage on a second side of the valve plate facing away from the first side can be closed or opened with the tappet.

The use of magnetic force to generate a restoring force for the plunger of the passive valve allows a particularly space-saving implementation of the injector, which takes up little space and allows a reduction in dimensioning, particularly in the longitudinal direction of the injector. Furthermore, a spring, which was previously required for urging the tappet of the passive valve in the closing direction, can advantageously be omitted, so that the susceptibility to faults (spring breakage, etc.) of the injector according to the invention is also improved.

Because the tappet of the passive valve, according to a preferred embodiment, can attach directly to the second side (for example the underside) of the valve plate, a particularly space-saving configuration of an injector results. Typically, in the prior art, a further sealing surface was provided for the implementation of the passive valve, which is arranged downstream of the valve plate, which inevitably leads to an axial enlargement of the injector. By now according to the invention the first side of the valve plate can be sealed by the actively switchable armature and the side of the valve plate facing away from it can be sealed by the plunger of the passive valve, resulting in a particularly space-saving configuration of an injector that is compact in the longitudinal direction.

According to a further optional development of the invention, it can be provided that when the passive valve is in a closed state, the tappet of the passive valve that can be moved back and forth is in contact with the second side of the valve plate in order to seal the at least one passage of the valve plate. In a closed position, the ram that can be moved back and forth makes contact with the second side (underside) of the valve plate and thus seals off the at least one passage penetrating the valve plate.

According to an advantageous modification of the present invention, it can be provided that in a closed state of the active valve, an armature of the active valve that can be moved back and forth in the longitudinal direction is in contact with the first side of the valve plate in order to seal the at least one passage of the valve plate, preferably wherein the injector further includes a coil configured to move the armature from its closed position by magnetic force.

On the first side (for example an upper side) of the valve plate, the at least one passage is usually selectively closed or opened with the aid of an armature that can be raised from a closed position via a coil. In a closed position, the armature seals the at least one passage of the valve plate, so that a fluid flow guided through the valve plate along the valve plate is prevented. In this case, a coil can optionally be provided which, when energized, generates a magnetic field which leads to the armature being raised, so that the at least one passage is released.

Advantageously, it can be provided according to the invention that the stop of the tappet contacting the valve plate is designed as a flat seal, conical seal and/or ball seal. It is clear to the person skilled in the art that a large number of possible contact pairings can lead to a desired sealing effect. However, the flat seal is particularly advantageous because during an opening process, in which the tappet is pushed away from the valve plate from a closing position, the fuel flow originating from the fuel supply line impinges directly on a flat plate, so that a high back pressure and large pressure forces arise act, which open the ram quickly and safely.

According to an optional development of the present invention, it can be provided that the injector also includes an urging device which is designed to urge the tappet of the passive valve towards the valve plate in the closed position.

This ensures that even if critical pressure peaks occur, for example generated during the combustion of the injected fuel, the passive valve is already in its closed position, so that the armature cannot be undesirably lifted out of its closed position.

According to a development of the present invention, it can be provided that the urging device comprises a spring element, preferably with the spring element being a spiral spring. The spring element is typically supported on a rigid stop arranged downstream of the plunger and urges the plunger in the direction of the closed position with a predetermined spring force.

According to a further advantageous development of the present invention, it can be provided that the urging device has at least one permanent magnet in order to move the plunger towards the valve plate in the closed position by means of magnetic force, preferably with the permanent magnet being arranged rigidly.

Alternatively or in addition to a spring element, magnetic force can also be used to urge or move the plunger into its closed position. A permanent magnet is useful here, which can be used in conjunction with ferromagnetic materials and/or another permanent magnet to move or urge the plunger into the desired closed position.

For example, it can be provided that the ram that can be moved back and forth has or is made of a ferromagnetic material and preferably the valve plate is designed as a permanent magnet or includes one in order to urge the ram into its closed position. The magnetism ensures that when the armature is closed on the first side of the valve plate, the tappet is pulled into the desired closed position due to the magnetic effect of the permanent magnet embodied in or arranged on the valve plate. The strength of the acting magnetic force is designed such that when the armature lifts and a fuel flow acts on the tappet, the tappet is lifted out of its closed position and fuel can be injected.

Furthermore, it can also be provided according to the invention that the tappet is designed as a permanent magnet or includes one and preferably the valve plate includes or consists of a ferromagnetic material in order to thereby move the tappet towards its closed position. This simply represents a reversal of the situation described above, so that the permanent magnet is now arranged on or embodied by the tappet and a magnetic force in combination with a ferromagnetically acting valve plate results in the tappet being urged into the closed position. It is clear to a person skilled in the art that, in order to achieve the identical effect, it is possible to exchange the permanent magnet and the ferromagnetic material.

According to a further advantageous embodiment of the present invention, it can be provided that the urging device has at least two permanent magnets in order to move the tappet by means of magnetic force towards the valve plate in the closed position, with the tappet preferably being designed as a second permanent magnet or such a permanent magnet in addition to a first permanent magnet includes.

By providing a further permanent magnet, not only the attractive effect of magnetism can now be used, for example, but also the repulsive effect that results when magnetic poles of the same polarity are aligned with one another in a near field. However, stronger magnetic fields can also be generated with several permanent magnets, for example when magnetic poles of different polarity are aligned with one another.

According to an optional development of the present invention, it can be provided that the valve plate is the first permanent magnet or includes it and the poles of the two permanent magnets are preferably aligned with one another in such a way that they attract one another.

If, in addition to the tappet, the valve plate is also a permanent magnet, it can be achieved by appropriately aligning the magnetic poles of the two permanent magnets that the tappet is in Rich direction valve plate is pulled. In this case, the pole of one permanent magnet must be aligned with one another with a differently oriented pole of the other permanent magnet.

According to an advantageous embodiment of the present invention, it can also be provided, in addition or as an alternative to the above, that a permanent magnet serves as a stop for the tappet in order to define a maximum distance between the tappet and the valve plate, with the poles of the two permanent magnets preferably being in relation to one another aligned so that they repel each other.

It is clear to a person skilled in the art that during regular operation of the injector, there does not have to be any contact between the permanent magnet acting as a stop and the tappet, since the mutually repelling effect of the two permanent magnets prevents this. Although there can be physical contact between the two permanent magnets, this is not mandatory.

Of course, it is also possible for both the valve plate, a permanent magnet and also a further permanent magnet arranged downstream of the tappet to be present, which together act on the tappet designed as a permanent magnet (or on a tappet having the same). This leads to the advantage that the magnetism of the individual permanent magnets does not have to be so pronounced, so that smaller or less expensive components can be used.

A further advantageous modification of the present invention can provide that the valve plate is made of a non-magnetizable material or a material that is only weakly magnetizable.

This is particularly advantageous when the tappet is in direct contact with the valve plate in the closed position, in order to prevent the valve tappet and valve plate from “sticking” due to magnetic attraction.

Furthermore, according to an advantageous modification of the present invention, it can be provided that a spacer element is provided between the valve plate and the tappet in order to set a maximum magnetic force between the valve plate and tappet, the spacer element preferably being a disk, a film or a valve plate and/or Plunger is attached coating, which is made of a non-magnetic or weakly magnetic material, in particular a plastic, for example. Polymide.

To make it easier to set the maximum desired magnetic force between the valve plate and the tappet, if the valve plate is designed as a permanent magnet or if it is made of ferromagnetic material, direct contact between the tappet and the magnetizable or magnetic valve plate can be prevented by providing a spacer element becomes. A coating or a non-magnetizable or only weakly magnetizable disk or layer arranged between the valve plate and the tappet can be considered as a spacer element, which defines the desired distance between the valve plate and the tappet that cannot be undercut. Plastic, in particular polyamide, can be used, for example, as the material for the spacer element. The tappet and/or the valve plate can also be provided with a corresponding coating.

The invention also 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 variants discussed above.

• 1: eine schematische Schnittansicht eines Injektors nach dem Stand der Technik,
• 2: eine Darstellung verschiedener Zustände von Bauteilen und Drücken in einem Injektor,
• 3: eine schematische Teilschnittansicht des Injektors mit Fokus auf die Ventilplatte,
• 4a-b: eine schematische Schnittansicht des Injektors n in einem geschlossenen und einem offenen Zustand,
• 5: eine schematische Teilschnittansicht des erfindungsgemäßen Injektors nach einer ersten Ausführungsform in einem geschlossenen Zustand,
• 6: eine schematische Teilschnittansicht des erfindungsgemäßen Injektors nach der ersten Ausführungsform in einem offenen Zustand,
• 7: eine schematische Teilschnittansicht des erfindungsgemäßen Injektors nach einer zweiten Ausführungsform, und
• 8: eine schematische Teilschnittansicht des erfindungsgemäßen Injektors nach einer dritten Ausführungsform,

Further features, details and advantages of the invention can be seen from the following description of the figures. show:

• 1 : a schematic sectional view of an injector according to the prior art,
• 2 : a representation of different states of components and pressures in an injector,
• 3 : a schematic partial sectional view of the injector with focus on the valve plate,
• 4a-b : a schematic sectional view of the injector n in a closed and an open state,
• 5 : a schematic partial sectional view of the injector according to a first embodiment in a closed state,
• 6 : a schematic partial sectional view of the injector according to the invention according to the first embodiment in an open state,
• 7 : a schematic partial sectional view of the injector according to the invention according to a second embodiment, and
• 8th : a schematic partial sectional view of the injector according to the invention according to a third embodiment,

The following detailed description of the figures 1 is explained using an injector for blowing in a gaseous fuel, but it is clear to the person skilled in the art that the invention also includes an injector for injecting a different fuel. Also, the pictorial representations, all of which show a valve plate that can be sealed from two sides, should not have the effect that this specific embodiment unduly restricts the idea of the present invention. According to the invention, an isolated passive valve arranged downstream of the valve plate is also included, in which the plunger is urged in the closing direction by means of magnetic force.

1 shows a longitudinal section of an injector 1 for blowing a gaseous fuel, such as hydrogen, into a combustion chamber. The injector 1 has an injector housing in which different components of the injector 1 are located. A fuel supply line 2 for introducing fuel into the injector 1 is provided on the connection side. First, the fuel or another combustible fluid (e.g. hydrogen) is fed through a hole in a cover 16 running approximately centrally in the injector housing and then through a fluid channel in an armature counterpart 19, a through-opening in the armature base 23 and the hollow interior of the armature 7, sometimes also called hollow needle 3 or just needle, to the end of armature 7 remote from the terminal side.

Depending on the position of the armature 7 relative to the valve plate 5, the openings A1 penetrating the valve plate 5 are closed or opened. in the in 1 In the state shown, the passages A1 are closed by the pressing of the armature 7 against the valve plate 5, since the end face of the armature 7 covers the opening contours of the passages A1. To improve the tightness, sealing elements 25 can be provided, which run around the opening contours of the passages A1 and contact the end face of the armature 7 in a sealing state. If the passages A1 are closed by the face of the armature 7, the fluid flow of the fuel at this point of the injector 1 is stopped and there is no downstream flow of fuel beyond the valve plate 5.

On the other hand, when the passages A1 are opened, which is implemented by lifting the armature 7 away from the valve plate 5 , the fuel introduced into the injector 1 with a certain pressure flows out and passes through the plurality of passages A1 on the side spaced apart from the armature 7 the valve plate 5. After flowing through a passive valve 4 provided in the injector 1, the pressurized fuel flows out of the injector through the injection cap 28. After flowing through the injection cap 28, the fuel delivered by the injector 1 is then typically located outside the injector 1 in a combustion chamber. In addition, the fuel is typically compressed in the combustion chamber 16, where the fuel then ignites or is ignited.

The passive valve 4, which is located on the side of the valve plate 5 facing away from the armature 7, serves to keep a very high pressure in the combustion chamber away from the armature 7. Otherwise it could happen that the very high pressure prevailing in the combustion chamber acts on the armature 7 and moves it away from its position closing the at least one passage A1. In a subsequent work step of the injector 1, the fuel required for combustion would then no longer be introduced into the combustion chamber, but an already at least partially burned mixture, which can lead to an interruption of the combustion process or, at best, to a lower performance of the combustion process.

The passive valve 4 has a valve tappet 6, a valve guide 27 and a valve spring 10, which urges the valve tappet 6 in a closing direction, so that fuel flows out via the opening contour A2 of the passive valve 4 only when on the valve plate 9 facing side of the passive valve 4 there is a pressure which is greater than the pressure prevailing on the side facing away from the passive valve 4 to the valve plate 5 by at least the restoring force of the valve tappet 6 exerted by the valve spring 10 . This prevents a fluid from flowing in from the side of the passive valve 4 facing the combustion chamber.

The armature 7 is reciprocally movable in the longitudinal direction of the injector 1 . The movement of the armature 7, which is in one piece or consists of an armature base 23 and an armature tip (also called a needle or hollow needle) can exist, is controlled via an active valve 3, which in the present representation of 1 is a solenoid valve. The armature 7 is designed in such a way that it reacts to the magnetic force generated by a coil 8 . Current can optionally flow through the coil 8 in such a way that the resulting magnetic force moves the armature 7 in the direction of the fuel connection 2 . This movement causes the armature 7 to be lifted relative to the valve plate 5. This opens up the passages A1 in the valve plate 5, so that the valve plate 5 can be traversed by fuel.

For a precise guidance of the armature 7 along the longitudinal axis of the injector 10, an armature guide 24 can be provided which encloses an outer side of the armature 7 on the peripheral side.

An air gap 22 is provided between the armature 7 and the armature counterpart 19 and is closed or reduced when the coil 8 is energized.

In order to improve the magnetic flux when the active valve 3 is implemented as a solenoid valve, the coil 8 can be surrounded on its peripheral outside by an iron yoke 21 in which the magnetic field can propagate particularly well. The situation is similar with the housing component directly surrounding the armature element 5 and the armature counterpart 27, which also preferably consists of a magnetizable material. So it can be advantageous if the pole tube 18, which is a part of the injector housing 2, is also made of iron or another ferromagnetic material. The same also applies to the armature counterpart 19, which advantageously also consists of a magnetizable material.

A visualized representation of the magnetic field lines is illustrated by the dotted, closed line that runs in a circle around the coil. The magnetic force pulls the armature element 7 (together with the armature base 23) towards the armature counterpart 19 and thus lifts it off the valve plate 5 or from the passages A1 breaking through the valve plate 5, so that fuel can flow towards the passive valve , from where fuel is finally introduced into the combustion chamber via the injection cap 28 .

2 shows the basic behavior of the injector 1 during an injection. In the starting position at time t ₀ at the bottom dead center (BDC) of the cylinder piston, the armature 7 and valve tappet 6 are pressed into their respective stops by the prestressed armature spring 17 or passive valve spring 10 and close the throttle points A1 or A2, which connect the needle chamber with the valve chamber or .connect the valve chamber with the injection chamber in the open state of the armature 7 or valve tappet 6. The pressure in the injector 1 corresponds to the pressure in the supply line, the pressure in the combustion chamber and in the injection chamber corresponds to the charge pressure during the intake phase of the cylinder piston, in which fresh air is sucked into the combustion chamber via the intake valves. The pressure in the valve chamber corresponds approximately to the combustion chamber pressure and depends, among other things, on the armature spring 17, the pressure in the combustion chamber during the phase in which the hot combustion gases are ejected via the outlet valves of the combustion chamber and any preceding injections. The functional representation is simplified below and does not take into account the gas exchange by opening and closing the intake and exhaust valves of the combustion chamber.

At time t ₁ , the control device applies a voltage signal via the electrical contacts to coil 8 of the actuator, so that current F1 in the electrical circuit rises to a defined end level. The current-carrying coil 8 induces a magnetic field in the actuator, whose magnetic field lines propagate in a toroidal shape around the coil (see Fig 1 ). The magnetic field builds up a magnetic force F2 in the air gap between armature 7 and armature counterpart 19, whereby at time t ₂ the armature 7 is attracted to the armature counterpart 19 as soon as the magnetic force F2 exceeds the closing force (sum of the prestressing force of the armature spring 17 and the pressure forces on the armature 7) surpasses. The build-up of the magnetic field and thus the magnetic force F2 is delayed by eddy currents in the iron parts of the magnetic circuit. The armature 7 is integrally or firmly connected to the armature base 23, so that the armature 7 moves uniformly with the armature stroke (or also: needle stroke) F3. As soon as the sealing element 25 on the valve plate 5 is no longer in contact with the end face of the armature 7 at time t ₃ , the connection between the needle chamber and the valve chamber is released, so that the fuel flows from the needle chamber into the valve chamber. This increases the pressure in the valve chamber. As soon as the pressure difference from the valve chamber to the injection chamber corresponds to a force difference on the valve tappet 6 of the same magnitude as the prestressing force of the valve spring 10, the passive valve 4 opens, i.e. the valve tappet 6 moves away from the seat along a valve tappet stroke F4 and establishes the connection between the valve chamber and the injection chamber freely, so that fuel flows from the valve chamber into the injection chamber. This leads to an increase in pressure in the injection space (cf. F8: pressure in the injection space). The fuel continues to flow downstream through the orifice(s) A3 in the injection cap 28 into the combustion chamber. The injection cap 28 is designed in such a way that the flow can be introduced into the combustion chamber in a defined state (jet orientation, inlet impulse, jet pattern, etc.). The open state of armature 7 and valve tappet 6 is maintained throughout the rest of the energization phase. The current level can be reduced (eg by a PWM voltage signal) as soon as the armature 7 is fully open and possible bouncing does not lead to the armature 7 closing. During injection, the engine cylinder is in the compression phase, so that the combustion chamber pressure F5 increases steadily.

In order to end the blowing-in process, the power supply is terminated by the control unit, so that the current F1 through the coil 8 is reduced to zero (time t ₄ ). Due to the eddy currents, the magnetic force F2 also decreases with a time delay. As soon as the magnetic force F2 is less than the sum of the closing force of the armature spring 17 and the hydraulic forces on the armature 7, the armature 7 begins to close uniformly (time t ₅ ); see also F3, F4. If the end face of the armature 7 hits the sealing element 25 of the valve plate 5, the connection between the needle chamber and the valve chamber is broken and the flow of fuel from the needle chamber into the valve chamber is interrupted (time t ₆ ). This reduces the pressure in valve chamber F7. If the pressure difference from valve chamber F7 to injection chamber F8 corresponds to a force difference on valve tappet 6 of the same magnitude as the valve spring force, valve tappet 6 moves back into its closed position on valve seat 27 and is pushed against the Seat 27 pressed, so that the fuel connection between the valve chamber and injection chamber (possibly after a phase of bouncing of the tappet on the valve seat 27) is interrupted (times t ₆ - t ₇ ). This completes the blowing-in process. During the further compression phase of the combustion chamber up to top dead center (TDC) in the period t ₇ - t ₈ , the air-fuel mixture in the injection chamber is compressed, while it expands in the subsequent expansion phase (period t ₈ - t ₉ ), with the further interim increase of the combustion chamber pressure F5 due to combustion is not shown here for the sake of simplicity. If the pressure in the combustion chamber falls so far that the difference between the pressure forces on the valve tappet 6 corresponds to the prestressing force of the armature spring 17 (time t ₉ ), the valve tappet 6 opens again briefly, so that part of the fuel in the valve chamber flows into the combustion chamber escapes. This process depends on the spring force and can occur repeatedly (period t ₉ - t ₁₀ )

The respective mass flow of the fuel via the passages A1 of the valve plate 5, the passages A2 of the tappet 6 and the passages A3 of the injection cap 28 is given as F9, F10 and F11.

3 shows a partial sectional view of an injector in the area of the valve plate, the at least one passage of which can be sealed from both sides of the valve plate by a respective valve insert (piston 6 and armature 7). It can be seen that the plunger 6 of the passive valve 4 is provided on an underside of the valve plate 5 and seals the passages A1 provided in the valve plate 5 by direct contact.

The plunger 6 is urged into its closed position by a spring element 10, the spring element 10 being supported on a stop arranged downstream. It can also be seen that the seal created by the tappet 6 on the underside of the valve plate 5 is a flat seal or a flat seat. The configuration shown with a direct seal on the underside of the valve plate 5 is very space-saving and allows very short injectors 1 in the longitudinal direction.

4a and 4b show a closed state ( 4a ) and an open state ( 4b ) of the injector 3 . In 4b the flow of fuel from the fuel supply line to the injection cap is shown with arrows and the movement of the components that is required to create the fluid connection between the fuel supply line and the injection cap is also highlighted by arrows. It can be seen that the armature is lifted out of its closed position due to energization of the coil, which means that the fuel, which is under high pressure, forces the tappet of the passive valve out of its closed position. If a corresponding movement of the components has taken place, the fuel, which is under high pressure, can flow out of the injector 1 from the fuel supply line to the injection cap.

5 shows a first embodiment of the present invention, in which the movable tappet 6 is now no longer urged into its closed position with the aid of a spring element, but with the aid of a magnetic force. As can be seen, the plunger and a stop arranged downstream of the plunger 6 are implemented by a respective permanent magnet 11, 12, with their orientation thereto results in poles of the two permanent magnets 11, 12 with the same orientation facing one another, so that the tappet 6, which can be moved back and forth in the longitudinal direction, is pushed away from the rigidly arranged stop 11 towards the valve plate 5. The provision of a spring element is therefore no longer absolutely necessary, since the repelling effect of the poles of the two permanent magnets 11, 12, which are oriented in the same way, has taken over this task. The dimensioning of the forces is designed according to the mode of action of the injector, so that even when the armature 7 is raised, the fuel under high pressure causes the plunger 6 to move in the direction of the stop 11 and fuel can flow out of the injector 1 .

6 shows the open state of the in 5 described embodiment of the injector 1, in which the armature 7 is lifted from its closed position and the fuel flow pushes the plunger 6 from its closed position. It does not necessarily have to come into contact between the two permanent magnets 11, 12, since the identical polarity of the two permanent magnets can also continue to cause a certain distance.

7 is another modification of the first embodiment ( 5 or 6 ), in which a spacer element 15 is arranged in the space between the valve plate 5 and the tappet 6 in order to prevent direct contact between the tappet 6 and the valve plate 5. This is particularly advantageous when the valve plate 5 is made of a ferromagnetic material, since the tappet 6 can then stick, and even the high-pressure fuel can no longer lead to opening. In order to avoid this effect of sticking, it can be provided that direct contact between tappet 6 and valve plate 5 is prevented, which can be implemented with the help of spacer element 15, for example in the form of a disk or a coating on valve plate 5 or tappet 6 can, is realized. The spacer element 15 can, for example, be a plastic, in particular polymide, or another non-magnetizable or only weakly magnetizable material.

8th shows a further embodiment in which the urging element 9 uses not only a spring force but also magnetic force in order to move the plunger 6 into its sealing position. The stop arranged downstream of the plunger 6 comprises a permanent magnet 11 and also serves as a support for a spring element 10 which urges the plunger 6 into the closed position. It is therefore not only the spring force that acts, but also the magnetic force emanating from the permanent magnets (11, 12) in the closed position of the plunger 6, which—as shown—can be designed as a permanent magnet or has one.

Reference List

1

injector

2

fuel line

3

active valve

4

passive valve

5

valve plate

6

pestle

7

anchor

8th

Kitchen sink

9

urging device

10

spring element

11

(first) permanent magnet

12

(second) permanent magnet

13

magnetic south pole

14

magnetic north pole

15

spacer element

16

housing cover

17

anchor spring

18

pole tube

19

anchor counterpart

20

bypass

21

iron inference

22

air gap

23

anchor base

24

Anchor Guide/Needle Guide

25

sealing element

26

blow pipe

27

valve guide

28

blow-in cap

A1

passage of the valve plate

A2

passage of the plunger

A3

Passage of the blowing cap

Claims (15)

Injector (1) for injecting fuel, preferably for blowing in a gaseous fuel, in particular hydrogen, comprising: a fuel supply line (2) for introducing a particularly gaseous fuel which is under high pressure, an active valve (3) which can be actively switched and is designed to selectively open or interrupt a flow connection from the fuel supply line (2) to an area downstream of the first side of the valve plate (5), in particular by at least one passage (A1) on a first side of a valve plate (5) through the active valve ( 3) is released or closed, and a passive valve (4), which is arranged downstream of the valve plate (5) and can be passively switched into a closing or releasing state by the different pressure conditions present upstream and downstream of the passive valve (4), characterized in that the passive valve (4) has a tappet (6) which is urged by magnetic force in the closing direction of the passive valve, and preferably wherein the at least one passage (A1) on a second side of the valve plate (5) facing away from the first side is connected to the tappet (6 ) is lockable or releasable. Injector (1) according to the previous one claim 1 , wherein when the passive valve (4) is in a closed state, the tappet (6) of the passive valve (4), which can be moved back and forth, is in contact with a second side of the valve plate (5) facing away from the active valve, in order to close the at least one passage (A1) of the Seal valve plate (5). Injector (1) according to one of the preceding claims, wherein in a closed state of the active valve (3) a reciprocating armature (7) of the active valve (3) is in contact with the first side of the valve plate (5) in order to sealing a passage (A1) of the valve plate (5), preferably wherein the injector further comprises a coil (8) which is designed to move the armature (7) from its closed position by means of magnetic force. Injector (1) according to one of the preceding claims, in which the stop of the tappet (6) which contacts the valve plate (5) is designed as a flat seal, conical seal and/or ball seal. Injector (1) according to one of the preceding claims, further comprising an urging device (9) which is designed to urge the tappet (6) of the passive valve (4) towards the valve plate (5) in the closed position. Injector (1) according to the previous one claim 5 , wherein the urging device (9) comprises a spring element (10), preferably wherein the spring element (10) is a spiral spring. Injector (1) according to one of the preceding Claims 5 or 6 , wherein the urging device (9) has at least one permanent magnet (11) in order to move the tappet (6) towards the valve plate (5) in the closed position by means of magnetic force, preferably wherein the permanent magnet (11) is arranged rigidly. Injector (1) according to one of the preceding Claims 5 - 7 , wherein the reciprocating plunger (6) comprises or is made of a ferromagnetic material and preferably the valve plate (5) is designed as a permanent magnet (11) or comprises such a device in order to move the plunger (6) towards its closed position . Injector (1) according to one of the preceding Claims 5 - 8th , wherein the tappet (6) is designed as a permanent magnet or comprises such and preferably the valve plate (5) comprises or consists of a ferromagnetic material in order to thereby move the tappet (6) towards its closed position. Injector (1) according to one of the preceding Claims 5 - 9 , wherein the urging device (9) has at least two permanent magnets (11, 12) in order to move the tappet (6) towards the valve plate (5) in the closed position by means of magnetic force, wherein, in addition to a first permanent magnet (11), the tappet (6) acts as a a second permanent magnet (12) is formed or includes such. Injector (1) according to the previous one claim 10 , wherein the valve plate (5) is or comprises the first permanent magnet (11) and preferably the poles (13, 14) of the two permanent magnets (11, 12) are aligned with one another in such a way that they attract one another. Injector (1) according to the previous one claim 10 or 11 , the first permanent magnet (11) serving as a stop for the tappet (6) in order to define a maximum distance between the tappet (6) and the valve plate (5), the poles (13, 14) of the two permanent magnets (11 , 12) are aligned to each other in such a way that they repel each other. Injector (1) after the previous one claim 12 , wherein the valve plate (5) is made of a non-magnetizable or only weakly magnetizable material. Injector (1) according to one of the preceding Claims 7 - 12 , wherein a spacer element (15) is provided between the valve plate (5) and the tappet (6) in order to set a maximum magnetic force between the valve plate (5) and the tappet (6), the spacer element (15) preferably being a disc, a film or a coating applied to the valve plate (5) and/or tappet (6), which is made of a non-magnetic or only weakly magnetic material, in particular a plastic, e.g. polymide. Internal combustion engine with fuel injection, in particular with gas direct injection, in particular with hydrogen direct injection, comprising an injector (1) according to one of the preceding ones Claims 1 - 14 .

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