EP0704620B1 - Fuel injection apparatus - Google Patents

Description

State of the art

The invention is based on a fuel injection device according to the preamble of claim 1.

From JP 61-104156 A is already a Fuel injector known, the downstream one Valve seat has a spray opening, which in turn downstream a mesh-like atomizer element follows. This atomizer element has a large number of meshes on each other by wedge-shaped in cross section Webs are separated. The cross sections of the wedge-shaped or triangular webs are steadily increasing from the upstream to the downstream face of the Atomizer element. With the help of the wedge-shaped, in downstream widening webs is said to be Line jet of fuel hitting the atomizer element be spread, especially the angles of the webs Influence the spray angle of the fuel.

It is already known from EP 0 302 660 A. Fuel injector known at its downstream An adapter is provided in the end of a Coming out fuel coming, which in turn on the downstream end of the adapter onto a flat, mesh metal disc to break up the fuel meets. The metal disc is arranged so that a Airflow through holes in the adapter ensures that at the Torn metal drops of stuck fuel drops become. Only then will a better atomization quality be achieved reached when the fuel near the metal disc of an air flow is included, but through which an accurate Spray geometry cannot be achieved. The square meshes of the metal disc are due to the uniform braid of equal size and form one in all Symmetrical checkered pattern. The braid of The metal disc is thus lattice-shaped, the Braid in the axial direction no changes in cross-section having. There are therefore no special atomizer edges intended.

It is also known from DE 27 23 280 A, on one Fuel injector downstream of a metering opening a fuel breaker in the form of a flat thin Run disc that has a variety of curved has narrow slits. The arcuate slots that introduced into the pane by etching, also provide their geometry, i.e. their radial width and their Arc length, for the formation of a fuel veil, that breaks up into small droplets. The etching process for The production of the slots is expensive. Furthermore the individual slot groups must be very precise to each other be brought in to break up the fuel desired way to achieve. Over the entire axial Extension of the rupture member have the arcuate Slit a constant opening width each. The So atomization is supposed to be horizontal, radial trained geometry of the slots in the plane of the Can be improved.

From the literature, for example from Heuberger: "Micromechanics", Springer-Verlag 1989, page 236 ff. And from Reichl: "Micro System Technologies 90", Springer-Verlag 1990, page 521 ff. Is the so-called LIGA process for production micromechanical components known. This method comprises the steps of Li thographie, G alvanoformung and molding. Extremely precise microstructures in very good quality and large quantities can be easily produced in this way. In contrast to, for example, EDM processes, the LIGA process can be used to produce an incomparably greater variety of geometries.

A device for is already known from WO 92/13188 A. Improve fuel atomization by adding Air in the liquid fuel before one Injector. The air is supplied on the intake side via an air jet pump at negative pressure in a fuel pump. The air is blown in via a only hole in the fuel flow path made so that the fuel is only ever in one place is enriched with inflowing air bubbles.

Advantages of the invention

The fuel injection device according to the invention with the Features of claim 1 has the Advantage that a low cost Atomizing grille on a fuel injector can be provided without any auxiliary energy contributes to a significant improvement in the quality of atomization, because the fuel hitting the atomizing grille is atomized particularly finely into tiny droplets that a reduced so-called Sauter Mean Diameter (SMD) have a reduced mean Drop diameter of the sprayed fuel. As Consequences can include the exhaust emission of one Internal combustion engine further reduced and also one Reduction in fuel consumption can be achieved.

This is achieved in that the Atomizing grille for fuel injection has completely new atomizer structures, which especially through a simple and very variable to manufacture in geometry, however, complicated arrangement of Atomizer bars with atomizer edges. The Have atomizer bars or the entire atomizer structure or not only points horizontally, i.e. radially running new geometries, but also in axial downstream extension, i.e. over the thickness of the Atomizing grating cross-sectional tapering, one enable optimal atomization of the fuel. Of the Erennstoff meets the sharp-edged Atomizer structures with their valve closing body facing atomizer edges, it becomes unstable and disintegrates into finer droplets. Downstream of the Atomizer edges occur due to the geometry of the Atomizer structure, specifically because of the Reduction in cross-section of the atomizer bars, to local ones Cavitation, i.e. negative pressure areas. The impact of the Fuel on the atomizer structure has also been used Consequence that in the atomized fuel downstream of the Atomizing edges of vortex and backflow occur, whereby this turbulence particularly increases the quality of atomization.

By the measures listed in the dependent claims advantageous developments and improvements in Claim 1 specified fuel injector possible.

It is particularly advantageous to use the atomizing grid the so-called LIGA or MIGA process. With high form accuracy are such large quantities of Atomizing grids with very small dimensions of the Atomizer structures can be produced. The atomizing grille can either be downstream of an orifice plate or directly downstream of a valve seat surface without additional Spray hole disk very easy on the injection valve for example by means of gluing, soldering, welding or Be snapped into place. If a spray washer Atomizing grille is connected to the Atomization grid a so-called secondary atomization instead of.

It can be advantageous to improve the atomization of the An additional gas injection device to provide. Before reaching the Fuel injector is in the fuel with this Device injected a gas. Advantageously the gas is supplied via an injection grille with a Variety of openings. The injection grille can also be produce very well using the LIGA process. For extraction the desired fuel pressure is immediately after the Gas injection the mixture of fuel and gas bubbles slowed down by the cross section for the fuel flow is enlarged again. With increasing pressure the Gas bubbles compressed in the mixture. Up to a certain one There is still a gas concentration in the mixture Bubble flows in the injection valve. Immediately downstream of a sealing edge of the Injector relax during the injection Gas bubbles suddenly and thus ensure a fine Atomization of the fuel. The sharp-edged The atomizer structure then immediately provides for a further atomization improvement according to the operations already mentioned.

drawing

Embodiments of the invention are in the drawing shown in simplified form and in the following Description explained in more detail. 1 shows it partially shown injection valve with Atomizing grids according to the invention, Figure 2 a simplified atomization area with a Atomizing grid, Figure 3 is an enlargement of the Atomizer structure from Figure 2, Figure 4 to Figure 9 Examples of atomizer structures with triangular, diamond-shaped or kite-quadrangular and at least partially curved cross sections, Figure 10 an atomizing grille with a square basic structure, Figure 11 is an atomizing grid with a circular Basic structure, Figure 12 with an atomizing grid hexagonal base structure, Figure 13 a Atomizing grille with triangular basic structure, figure 14 shows a schematic illustration of the fuel injection device with a gas injection device, Figure 15 Exemplary embodiment of a gas injection device and FIG. 16 an injection grille for a gas injection device.

Description of the embodiments

A valve is shown in FIG. 1 as an exemplary embodiment the shape of an injector for Fuel injection systems from mixture compressors spark-ignited internal combustion engines partially shown. The injector has a tubular valve seat support 1, in which a valve axis 2 concentric Longitudinal opening 3 is formed. In the longitudinal opening 3 is a z. B. tubular valve needle 5 arranged on the its downstream end 6 with a z. B. spherical Valve closing body 7, for example five on the circumference Flattenings 8 are provided, is connected.

The injection valve is actuated in a known manner Way, for example electromagnetic. For axial Movement of the valve needle 5 and thus to open against the Spring force of a return spring (not shown) or An indicated closing serves to close the injection valve electromagnetic circuit with a magnetic coil 10, one Anchor 11 and a core 12. The anchor 11 is with the End of valve needle 5 facing away from valve closing body 7 through z. B. connected a weld using a laser and aligned with the core 12.

To guide the valve closing body 7 during the A guide opening 15 serves for axial movement Valve seat body 16. In the downstream, the core 12 opposite end of the valve seat support 1 is in the concentric to the longitudinal axis 2 of the valve Longitudinal opening 3 of the cylindrical valve seat body 16 through Welding tightly assembled. At its the valve closing body 7 facing away, lower end face 17 is the Valve seat body 16 with a cup-shaped, for example trained spray plate 21 concentric and firm connected, that is, directly to the valve seat body 16 is present.

The connection of valve seat body 16 and spray orifice plate 21 is carried out, for example, by a circumferential and dense, first weld seam 22 formed by a laser. With this type of assembly there is a risk of undesired deformation of the spray plate 21 in her central area 24, in which at least one, for example, four formed by stamping or eroding Spray holes 25 are avoided. The spray hole disc 21 is further with the wall of the longitudinal opening 3 in Valve seat support 1, for example, by a rotating and tight second weld 30 connected.

The insertion depth of the valve seat body 16 and pot-shaped spray plate 21 existing Valve seat part in the longitudinal opening 3 determines the size of the Hubs of the valve needle 5, since the one end position of the Valve needle 5 when the solenoid 10 is not energized by the System valve body 7 against a valve seat surface 29 of the valve seat body 16 is fixed. The other The end position of the valve needle 5 is when the solenoid is excited 10, for example, by the anchor 11 resting against the core 12 set. The path between these two end positions the valve needle 5 thus represents the stroke.

The spherical valve closing body 7 acts with the in Direction of flow tapering in the shape of a truncated cone Valve seat surface 29 of the valve seat body 16 together, the in the axial direction between the guide opening 15 and the lower end face 17 of the valve seat body 16 is formed is.

Downstream of the orifice plate 21 is in the Longitudinal opening 3 of the valve seat support 1 an inventive Atomizing grid 32 arranged. The atomizing grille 32 represents a thin disc with the valve seat support 1 is firmly connected for example by gluing. Of the The area of attachment of the atomizing grille 32 is in of Figure 1 shown only as an example and schematically, because the various connection techniques 33 for fixing the Atomizing grid 32 can be used, such as. B. Welding, soldering or snapping. Alternatively to that for example glued in the longitudinal opening 3 Atomizing grid 32 is a second one in FIG Atomizing grille 32 shown in the circumferential direction is limited by a circumferential clamping ring 34. By doing Clamping ring 34, the atomizing grid 32 is clamped, clamped or cast. The clamping ring 34 enables one very easy assembly of the atomizing grille 32, since that Atomizing grille 32 with the clamping ring 34 in one Process step between the downstream end of the Valve seat support 1 and the downstream end of the injector-forming protective cap 35 is clamped can be. The assembly can take place, for example, that the atomizing grille 32 is already in the protective cap 35 inserted and then together with the protective cap 35 on Valve seat carrier 1 is fastened by the protective cap 35 and the valve seat support 1 enter into a latching connection. Other not described here, but quite common Joining methods 33, such as welding or soldering, are also conceivable for attaching the atomizing grid 32. The Connection techniques 33, however, only play one subordinate role, since atomizer structures 36 in middle areas 37 of the invention Atomizing grid 32 is critical to a desired one excellent atomization quality of the fuel.

The four injection holes 25, for example Spray plate 21 are z. B. symmetrically around the Longitudinal valve axis 2 in the form of corner points of a square distributed and thus have the same distance to each other and to the valve longitudinal axis 2. The from the Spray holes 25 emerging fuel jets collide downstream of the spray plate 21 with the Atomizing structures 36 of the atomizing grid 32 Colliding or impact and flow around the fuel the atomizer structures 36 according to the invention provides a particularly effective preparation method, in which one Atomization takes place in particularly small droplets and the is explained in more detail below. On the atomizing grille 32 so there is a so-called secondary atomization, through which the fuel droplets continue to grow in size be reduced. The arrangement of the spray plate 21 is under no circumstances a condition for the optimal working of the Atomizing grid 32; rather, it turns out Atomizer arrangement without spray plate 21 downstream the valve seat surface 29 in the injection valve as special effective.

To explain the treatment principle in more detail, the Figure 2 simplifies the spray area of the Injector, especially the areas around the Valve seat surface 29 and the atomizing grid 32 around. A spray orifice plate 21 is not provided. Of the when lifted from the valve seat surface 29 Valve closing body 7 in the direction of the atomizing grille 32 so delivered fuel hits immediately without Influencing a spray plate 21 on the Atomizer structure 36.

With the atomizing grid 32 according to the invention especially the atomization quality of the fuel without additional auxiliary energy can be improved, whereby in particular the new geometries of the atomizer structure 36 contribute. So far it has been common for injectors the atomization of the fuel, among other means Spraying disks 21 to make. The pressure drop at the Spray plate 21 is about 90% of Pressure difference between the injector and one is not illustrated intake manifold of the internal combustion engine. The Pressure energy becomes more turbulent due to viscous friction Dissipation in thermal energy and also in kinetic Energy converted. In the spray holes 25 of the Spray plate 21 takes the speed of Due to the narrowing of the cross-section, which is a factor in the atomization quality of the fuel. By contact with the sharp edges of the Spray holes 25 are due to the disturbance of the surface of the fluid, here the fuel, and the formation of local cavitation the fuel jets downstream of the Spray plate 21 unstable and turbulent.

For a good atomization of the fuel there is turbulence of the fluid jet required, which can be in a large Expresses Reynold's number. To realize the turbulence the fuel jet offers z. B. the invention Atomizer structure 36 with its special geometry. In 2 shows the atomizer structure 36 and the Fluid movements shown schematically. The pressure drop on the atomizing grille 32 is transverse due to its relatively large size to the longitudinal axis 2 of the cross-sectional areas of Flow areas 38 between the atomizer structures 36 much less than the pressure drop across the Spray hole disk 21. Therefore a large part is shifting of the total pressure drop in the injection valve to a sealing edge 39, which is formed on the valve seat 29 right there, where the valve closing body 7 in the closed state of the Injector largely with a line contact on the Valve seat surface 29 abuts. As a result, the Flow velocity of the fluid jet 40 upstream of the atomizing grid 32 is higher than in the case of a following one Spray plate 21 so that a high quality Atomization on the atomizer structure 36 is possible.

FIG. 3 shows a partial area of the Atomizing grid 32 is shown enlarged, the triangular grid profile in cross section particularly becomes clear. The atomizing grid 32 has e.g. Legs such a triangular atomizer structure 36 that a flat Surface 41 with an inner and outer atomizing edge 42 to the valve closing body 7 shows while a Triangle tip 43 facing away from the valve closing body 7 is trained. The atomization process of the fuel is recognizable from the figure 3. The fluid jet 40 with a large inflow velocity, which is indicated by an arrow 45 is indicated, is initially due to the flow at the sharp-edged atomizer structure 36, especially on the Atomizer edges 42 are unstable and then disintegrate into fine Droplet. From the atomizer edges 42 extending Streamlines 47 illustrate the instability of the Fuel. It comes downstream of the atomizer edges 42 due to the triangular geometry of the atomizer structure 36 to local cavitations 48, i.e. negative pressure areas. The Impact of the fuel on the atomizer structure 36 has also as a result that in the atomized fuel downstream of the atomizer edges 42 vortices or Reverse flows 49 occur. The atomization of the fuel is also caused by aerodynamic forces in the ambient air improved. The result is a tiny droplet formed fine fuel mist before, the Fuel droplets through a significantly reduced so-called Sauter Mean Diameter (SMD), i.e. one reduced mean drop diameter of the hosed Fuel.

The aim of this type of preparation is to be particularly fine atomized fuel in the form of tiny droplets from the Spray injector, for example, very low To achieve exhaust gas emissions from the internal combustion engine and Reduce fuel consumption. With the atomizing grille 32 can do precisely this requirement in a particularly advantageous manner be fulfilled. By tearing the fuel on Atomizing grid 32 is created downstream of the Atomizing grating 32 of the fine just described Droplet mist. These particularly small, the droplet mist forming fuel droplets now have an essential larger surface area than the fuel jets before Impingement on the atomizing grille 32, which in turn for good atomization is an indication. You can also do it speak that a downstream of the atomizing grille 32 Fuel spray is formed. This just described Mode of action also records all of the following Embodiments of the atomizer structures 36.

Figures 4 to 9 are some advantageous and simple producible atomizer structures 36 in cross section shown in atomizing grids 32 for Injectors can be used. The angles of the Fuel sprays can be different Geometries of the atomizer structures 36 can be varied. The Figures 4 and 5 show triangular atomizer structures 36, which differ from each other by their angles. On the triangular tip 43 facing away from the valve closing body 7 there is, for example, an acute angle (FIG. 4) and in the embodiment in Figure 5 an obtuse angle in front. Further exemplary embodiments for atomizer structures 36 are shown in Figures 6 and 7, the Atomizer structures 36 here a diamond or have a kite-shaped cross-section. The fuel does not meet one of these atomizer structures 36 Flat surface perpendicular to the longitudinal axis of the valve 2 41, but on two diagonally to the valve longitudinal axis 2 extending surfaces 44 which are adjacent to the two atomizer edges 42 still another towards the valve closing body 7 have directed tear-off edge 50 which is exactly between the two inclined surfaces 44. The working examples 8 and 9 each have a flat surface 41 and a curved surface 46, the curved, the Valve closing body 7 facing away from surface 46 both with a shaped constant as well as with a variable radius can be. The transitions from the flat surface 41 to the curved surface 46 each represent the two Atomizer edges 42.

Figures 10 to 13 show some embodiments of Atomizing grids 32 in their plan view and clarify thus the arrangement of the atomizer structures 36 also in radial extension. The circular atomizing grille 32 each have an outer annular edge zone 52 on the central region 37 in the circumferential direction with the atomizer structure 36 and between them resulting flow areas 38 completely surrounds. The Atomizer structures 36 can be made and manufactured very variably tailored to the desired forms of fuel mist become. The atomizer structures 36 thus have in their Basic tendency, for example, quadrangular (FIG. 10), circular (Figure 11), hexagonal (Figure 12) or triangular (Figure 13) geometries. Besides this Basic structure 53 in the atomizing grid 32 are shown in FIGS Atomizer structures 36 mostly by one Center 54 of the atomizing grid 32 extending and from the edge zone 52 outgoing atomizer webs 55 are provided. These atomizer webs 55 cross according to the training the basic structure 53 of the atomizer structure 36 below different angles. This is how the atomizer webs 55 run with the circular basic structure 53 (FIG. 11) for example at right angles to each other from the Edge zone 52 to the center 54, while the atomizer webs 55 for the hexagonal basic structure 53 (FIG. 12) enclose an angle of 60 ° each. In the triangular basic structure 53 (FIG. 13) are the Atomizer bars 55 z. B. at an angle of 120 ° introduced and run entirely within the triangular basic structure 53, since this is also from the Edge zone 52 is formed starting.

In contrast, the circular, the quadrangular or the hexagonal basic structure 53 with radial Distance from the edge zone 52 inside the Atomizing grid 32 is formed. Since the atomizer webs 55 run from the edge zone 52 to the center point 54 and thereby cross the basic structure 53, arise both between the edge zone 52 and the basic structure 53 as well as between the basic structure 53 and the center point 54 Flow areas 38. In the atomizer structure 36 with the hexagonal base structure 53 are characterized by the Atomizer webs 55 consequently six outer and six inner Flow areas 38 formed. The atomizer structure 36 with the square-shaped basic structure 53 z. B. like this trained that the atomizer webs forming the square 55 each run to the edge zone 52, while within the square-shaped basic structure 53 in the form of a cross Atomizer webs 55 are arranged, making four Flow areas 38 within the basic structure 53 arise. Between the quadrangular basic structure 53 and the edge zone 52 result from the arrangement of the Atomizer bars 55 z. B. eight flow areas 38, wherein in each case four flow areas 38 of the same size exhibit.

The method applied, which is three-dimensional particularly for the production - For the preparation of the atomizing grid 32 as a metal grid with these atomizing 36, the so-called LIGA example, (Li thographie, G alvanoformung, A bformung) - or MIGA (Mi krostrukturierung, G alvanoformung, A bformung) Microstructures are suitable. The LIGA process is described in more detail, for example, in Heuberger: "Micromechanics", Springer-Verlag 1989, page 236 ff. And in Reichl: "Micro System Technologies 90", Springer-Verlag 1990, page 521 ff resist structuring was carried out by means of optical lithography. From a mask, the corresponding structures on the resist-coated substrate surface z. B. transmitted by means of projection exposure. After the resist development, a structured resist profile is available on the carrier, which can now be processed further. Since the micromechanical application possibilities of lacquer profiles are limited, a galvanoplastic impression of the resist structures is appropriate. All galvanic metals (e.g. nickel sulfamate) can be considered as materials for this. The metallic structures created after electroforming can then be reproduced using conventional impression techniques. For this purpose, a plastic intermediate mold is first to be produced, from which z. B. the final workpiece can be produced by means of electroplating. Particularly advantageous in the LIGA process is the fact that a variety of materials can be used, e.g. B. metals, plastics or ceramics, and a production of large quantities is possible at the same time. Atomizer structures 36 or atomizer webs 55, which have a greatest width between <50 μm and 200 μm and an axial extension, that is to say a profile height of approximately 200 μm, can be produced with the aforementioned methods without any problems.

The atomizer structures 36 can also be used, for example Plastic injection molding can be generated. Some are suitable for this plastics resistant to fuels, in particular Polyether ether ketone (PEEK), polyphenylene sulfide (PPS), Epoxy resin (EP) and phenolic resin (PH). With injection molding very precise structures can also be achieved, the sharp one Have atomizer edges 42. Because of a desired The individual atomizer bars 55 should have inherent stability a minimum width at its widest point of 100 µm and have a minimum profile height of 100 µm. You can also the atomizer structures 36 by known means Silicon technology z. B. are produced by etching.

A further improvement in the atomization quality of the Fuel is attainable if the fuel is with gas, for example with air. Figure 14 shows a schematic representation of a Fuel injector, in which one Gas injector 57 an injection valve with the The atomizer structure 36 according to the invention is connected upstream. The gas injection device 57 is, for example, between a mass flow sensor, not shown, and the Injector arranged. The gas supply 58 in the Gas injection device 57 is, for example, vertical to the direction of fuel flow.

An exemplary embodiment is shown in FIG Gas injection device 57 enlarged compared to FIG. 14 shown again schematically as a single component. The Gas injection device 57 is designed so that in a clear gas injection area 59 Cross-sectional constriction 60 is provided for the fuel. There is therefore a narrow gap in the gas injection region 59 Flow through the fuel before. The speed of the Erennstoff takes 60 due to the narrowing of the cross-section noticeably too, with those flowing in with a system pressure Fuel stored pressure energy in kinetic energy is converted. In the fuel with low overpressure The gas is now blown in at, for example, 0.5 bar.

To supply the gas for improved treatment and atomization of the fuel is used at the Gas injection device 57 an inlet port 61 is provided. As a gas z. B. by a bypass in front of one Throttle valve in an intake manifold of the internal combustion engine branched suction air, conveyed by an additional fan Air, but also recirculated exhaust gas from the internal combustion engine or a mixture of air and exhaust gas can be used. The Use of recirculated exhaust gas enables a reduction the pollutant emission of the internal combustion engine. The feeder of the gas up to the gas injector 57 is not shown in more detail.

From the inlet port 61, the gas enters a chamber 63 leading to the cross-sectional constriction 60 from one disk-shaped inlet grille 64 is limited. The Gas injection device 57 can also be designed such that in two chambers 63 and two inlet grille 64 gas in the fuel is inflatable, with the chambers 63 can be connected or separated from each other with gas via different inlet connections 61 can be supplied. Furthermore, it is possible to use one Chamber 63 with an annular cross section and one internally delimiting tubular injection grille 64 to provide. Instead of the inlet grille 64 in the Gas injector 57 also has several perforated tubes be used. About molded in the injection grille 64 Openings 66 direct the gas into the fuel.

To obtain the desired fuel pressure, directly after the gas injection, the mixture of fuel and Gas bubbles 67 slowed down by the cross section for the Fuel flow, for example, back to the size of the Cross section when entering the gas injection device 57 is enlarged. With increasing pressure, the gas bubbles become 67 compressed in the mixture. Because of the surface tension between gas and fuel is depending on the bubble size Pressure in the gas bubbles 67 correspondingly higher than that Mixture pressure. Up to a certain gas concentration in the There is still a bubbly flow in the mixture Injector. Immediately downstream of the sealing edge 39 the gas bubbles 67 relax during the injection suddenly. The process is called a bubble explosion referred to after the "shear-type" decay mechanisms of Fuel ensures a very fine atomization. The sharp-edged atomizer structure 36 then ensures immediately below for further improvement in Atomization quality according to that already described Operations. When using fuel with gas bubbles 67 should be between the sealing edge 39 and the atomizer structure 36 can be dispensed with the spray plate 21 to a To avoid bubble clogging in the spray holes 25.

An embodiment of the injection grille 64 is shown in FIG Figure 16 shown. The injection grille 64 provides represents a rectangular base body, the edge lengths of which are e.g. be between 1 mm and 5 mm and in which a variety of Openings 66 are arranged in a sieve-like manner, so that one of a perforated film can speak. The one already described LIGA process can also be used to manufacture the injection grille 64 can be used very well. Here are the injection grilles 64 in very large quantities with high dimensional accuracy producible. Instead of that shown in Figure 16 Injection grids 64 are also other sieve or lattice-shaped Blowing agent conceivable. As the smallest with the LIGA process Structures can be manufactured precisely, it is possible at any time the inlet grille 64 with openings 66, the diameter z. B. have between 10 µm and 50 µm.

Claims (17)

1. Fuel injection device for fuel injection systems of internal combustion engines, with a fuel injection valve, with a valve longitudinal axis (2), with a valve closing body (7) which cooperates with a valve seat face (29), with at least one spray orifice (25) and with an atomizing grid (32) arranged downstream of the at least one spray orifice (25), the atomizing grid (32) is equipped with an atomizing structure (36) which at least partially possesses taperings in cross section in the axial, downstream direction, that is to say over the thickness of the atomizing grid (32), the atomizing structure (36) containing throughflow regions (38) having cross-sectional areas extending transversely relative to the valve longitudinal axis (2), and the cross sectional areas being at least partially enlarged in the axial, downstream direction.
2. Device according to Claim 1, wherein the atomizing structure (36) of the atomizing grid (32) has at least partially a triangular cross section in the axial direction.
3. Device according to Claim 2, wherein the atomizing structure (36) possessing a triangular cross section is designed with a plane face (41) extending perpendicularly to the valve longitudinal axis (2) and facing the valve closing body (7), with atomizing edges (42) limiting the face (41), whilst a triangle vertex (43) is provided so as to face away from the valve closing body (7).
4. Device according to Claim 1, wherein the atomizing structure (36) of the atomizing grid (32) has at least partially a square cross section in the axial direction.
5. Device according to Claim 4, wherein the atomizing structure (36) has the cross section in the form of a kite square, a breakup edge (50) being formed nearest the valve closing body (7), whilst further atomizing edges (42) follow only further downstream.
6. Device according to Claim 1, wherein the atomizing structure (36) of the atomizing grid (32) has in the axial direction a cross section possessing at least partially curved limitations.
7. Device according to Claim 6, wherein the curved limitations are formed by curved faces (46), and the faces (46) of the atomizing structure (36) face away from the valve closing body (7), whilst a plane face (41) having atomizing edges (42) is designed to face the valve closing body (7).
8. Device according to one of the preceding claims, wherein the atomizing grid (32) is made circular, an annular edge zone (52) completely surrounding a middle region (37) having the atomizing structure (36).
9. Device according to Claim 8, wherein the atomizing structure (36) possesses, in the middle region (37) of the atomizing grid (32), a basic geometrical structure (53) which is connected at least partially via atomizing webs (55) to the edge zone (52).
10. Device according to Claim 8, wherein the atomizing structure (36) possesses, in the middle region (37) of the atomizing grid (32), a basic geometrical structure (53) which extends directly out of the edge zone (52).
11. Device according to Claim 9, wherein the atomizing webs (55) which do not belong to the basic structure (53) pass through a midpoint (54) of the atomizing grid (32).
12. Device according to Claim 9 or 10, wherein the basic structure (53) has the form of a polygon.
13. Device according to Claim 9, wherein the basic structure (53) has the form of a circle.
14. Device according to one of the preceding claims, wherein the atomizing structure (36) of the atomizing grid (32) is produced by means of LIGA, i.e. Lithographie, Galvanoformung, Abformung [Lithography, Electroforming, Cast-taking], or MIGA Mikrostrukturierung, Galvanoformung, Abformung [Microstructuring, Electroforming, Cast-taking] processes, plastic injection-moulding or etching.
15. Device according to Claim 1, wherein the fuel injection valve is preceded by a gas blow-in device (57), by means of which gas bubbles (67) are blown into the fuel to be sprayed.
16. Device according to Claim 15, wherein the direct feed of gas to the fuel takes place in the gas blow-in device (57) via at least one blow-in grid (64) which has a multiplicity of orifices (66).
17. Device according to Claim 16, wherein the blow-in grid (64) is produced by means of LIGA or MIGA processes.

Images