EP1799996A1

EP1799996A1 - Fuel injection valve

Info

Publication number: EP1799996A1
Application number: EP05794491A
Authority: EP
Inventors: Markus Gesk; Guenter Dantes; Joerg Heyse; Andreas Krause
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2004-10-09
Filing date: 2005-09-20
Publication date: 2007-06-27
Anticipated expiration: 2025-09-20
Also published as: DE502005009285D1; DE102004049280A1; JP4646256B2; WO2006040246A1; CN101035980A; CN101035980B; EP1799996B1; JP2008516136A; US20090200402A1

Abstract

Disclosed is a fuel injection valve which is characterized in that a perforated disk (23) that is provided with a plurality of discharge ports (24) is disposed downstream of a valve seat member (16) comprising a fixed valve seat (29). An inlet port (19) encompassing an annular hollow inflow space (26) is provided directly upstream of the discharge ports (24). The valve seat member (16) covers the hollow inflow space (26) in such a way that the discharge ports (24) of the perforated disk (23) which are located downstream are covered up. Each discharge port (24) is provided with one inlet zone (33) whose diameter D1 is significantly greater than the diameter D2 of a zone which is located immediately downstream thereof at a sharp angle and forms the narrowest cross section of the discharge port (24), the discharge port (24) expanding in a trumpet-shaped fashion to a diameter D3 from said zone in the direction of flow. The inventive fuel injection valve is particularly suitable for use in fuel injection systems of mixture-compressing spark-ignited internal combustion engines.

Description

Fuel injector

State of the art

The invention relates to a fuel injection valve according to the preamble of the main claim.

DE 4221 185 A1 already discloses a fuel injection valve which has a perforated disc with a plurality of outlet openings downstream of a fixed valve seat. The perforated disc is initially provided with at least one outlet opening by punching, which runs parallel to the valve longitudinal axis. Then, the perforated disc is plastically deformed in its central region, which has the outlet openings, by deep drawing, so that the outlet openings extend inclined relative to the longitudinal axis of the valve and engage in

Expand flow direction in the form of a truncated cone or conical. In this way, a good treatment and a good jet stability of the discharged through the outlet openings medium are achieved compared to previously known injectors, however, the production process of the perforated disc with its outlet openings is very expensive. The outlet openings are provided immediately downstream of an outlet opening in the valve seat body and are thus directly flowed.

From JP 2001-046919 A, a fuel injection valve is already known in which a perforated disc with a plurality of outlet openings is provided downstream of the valve seat. In this case, an inlet opening with a larger diameter is formed between an outlet opening in the valve seat body and the perforated disk, which forms an annular inflow cavity for the outlet openings. The outlet openings of the perforated disc are in direct flow communication with the inflow opening and the annular inflow cavity and are thereby from the upper boundary of the inflow opening covered. In other words, there is a complete offset from the outlet port defining the inlet of the inflow port and the outlet ports. Due to the radial offset of the outlet openings relative to the outlet opening in the valve seat body results in an S-shaped flow pattern of the fuel, which is an atomization-promoting measure. The inflow opening defining the S-shaped course of the flow has a continuously constant height.

From DE 196 07 277 Al a fuel injection valve with a perforated disc is already known, which has a plurality of different opening geometries having functional levels. The individual functional levels of the perforated disc are galvanic

Metal deposition (multilayer electroplating) built on each other. In this injection valve, the valve seat body should in no case limit or cover the inlet openings in the upper functional level of the perforated disc.

Advantages of the invention

The fuel injection valve according to the invention with the characterizing features of the main claim has the advantage that in a simple manner uniform atomization of the fuel is achieved, with a particularly high quality of preparation and Zerstäubungsgüte is achieved with very small fuel droplets. This is achieved in an advantageous manner in that downstream of a valve seat, a perforated disc is provided as atomizing disc with a specific geometry of the outlet openings. With the perforated disk according to the invention, fuel sprays can be sprayed off with an atomization quality which is about 20 μm for the SMD, the so-called Sauter Mean Diameter of the fuel droplets, as an essential measure of the atomization quality.

The horizontal velocity components of the flow entering the outlet openings are not obstructed by the wall of the respective outlet opening at the entrance level, so that the fuel jet, when leaving the outlet opening, has the full intensity of the horizontal components generated in the onflow cavity and therefore fanned with maximum atomization.

The measures listed in the dependent claims advantageous refinements and improvements of the main claim fuel injector are possible. Advantageously, in the valve seat body upstream of the Auslassöffiiungen an inflow opening with the annular Anströmhohlraum is provided, which is greater than an outlet opening downstream of the valve seat. In this way, the valve seat body already assumes the function of influencing the flow in the perforated disk. In a particularly advantageous manner, the formation of the inflow opening achieves an S-blow in the flow for atomization improvement of the fuel, since the valve-seat body with the upper boundary of the inflow opening covers the outlet openings of the perforated disk.

By means of electrodeposition, the perforated disks can be produced in a reproducible manner in an extremely precise and cost-effective manner in very large numbers simultaneously. In addition, this production allows an extremely large design freedom, since the contours of the openings in the perforated disc can be selected freely.

drawing

Embodiments of the invention are shown in simplified form in the drawing and explained in more detail in the following description. 1 shows a partially illustrated injection valve, Figure 2 shows the detail II in Figure 1 with a Anströmhohlraum in the valve seat body and a plurality of outlet openings perforated disc in an enlarged view, Figure 3 shows a first embodiment of an inventively shaped outlet opening, Figure 4 shows a second embodiment an outlet opening formed according to the invention and FIGS. 5A to 5C show three production steps for producing a perforated disk according to the invention in the region of an outlet opening.

Description of the embodiments

In the figure 1 is shown as an embodiment, a valve in the form of an injection valve for fuel injection systems of mixture-compression spark-ignition internal combustion engines partially. The injection valve has a tubular valve seat carrier 1, which only schematically indicates a part of a valve housing and in which a longitudinal opening 3 is formed concentrically to a valve longitudinal axis 2. In the longitudinal opening 3 is a z. B. tubular valve needle 5, which at its downstream end 6 with a z. B. - A -

Spherical valve closing body 7, on whose circumference, for example, five flats 8 are provided for flowing past the fuel, is firmly connected.

The actuation of the injection valve takes place in a known manner, for example electromagnetically. For axial movement of the valve needle 5 and thus to open against the spring force of a return spring or closing the injector, not shown, is a schematically indicated electromagnetic circuit with a solenoid 10, an armature 11 and a core 12. The armature 11 is connected to the valve closing body. 7 opposite end of the valve needle 5 by eg a trained by a laser weld and aligned with the core 12.

In the downstream end of the valve seat carrier 1 is a valve seat body 16, e.g. tightly assembled by welding. On its lower end face 17 facing away from the valve closing body 7, the valve seat body 16 is stepped, with a depression 20 being provided in a middle region around the valve longitudinal axis 2, in which a flat, single-pored perforated disk 23 is introduced. The perforated disc 23 has a plurality of outlet openings 24, ideally up to four hundred outlet openings 24 due to the small opening widths. Upstream of the recess 20 and thus of the outlet openings 24 of the perforated disc 23, an inflow opening 19 is provided in the valve seat body 16, via which the individual outlet openings 24 are flown. The inflow opening 19 has a

Diameter which is greater than the opening width of an outlet opening 27 in the valve seat body 16, from which the fuel flows incoming into the inflow opening 19 and ultimately into the outlet openings 24.

The inflow opening 19 is designed in the immediate inflow region of the outlet openings 24 with a special geometry. The annular region of the inflow opening 19 which is larger in diameter relative to the outlet opening 27 is shown enlarged in FIG. 2 and is referred to below as the inflow cavity 26.

The connection of valve seat body 16 and perforated disc 23 is effected for example by a circumferential and dense, formed by a laser weld 25, which is placed outside of the inflow opening 19. After attachment of the perforated disc 23, this is sunk in the recess 20 opposite the end face 17th The insertion depth of the valve seat body 16 with the perforated disc 23 in the Längsöfmung 3 determines the size of the stroke of the valve needle 5, since the one end position of the valve needle 5 with non-energized solenoid 10 by the system of the valve closing body 7 at a downstream conically tapered valve seat surface 29 of the valve seat body 16 is set. The other end position of the valve needle 5 is fixed in the excited magnet coil 10, for example, by the system of the armature 11 to the core 12. The path between these two end positions of the valve needle 5 thus represents the hub.

The outlet openings 24 of the perforated disc 23 are in direct flow communication with the inflow opening 19 and the annular inflow cavity 26 and are thereby covered by the upper boundary of the inflow opening 19. In other words, there is a complete offset of the outlet opening 27 and the outlet openings 24 defining the inlet of the inflow opening 19. Due to the radial offset of the outlet openings 24 with respect to the outlet opening 27 results in an S-shaped flow pattern of the medium, here the fuel.

By the so-called S-blow before and within the perforated disc 23 with several strong flow deflections of the flow is a strong, atomization promoting turbulence impressed. The velocity gradient across the flow is thus particularly pronounced. It is an expression of the change in the velocity across the stream, with the velocity in the middle of the flow much greater than that in the vicinity of the walls. The increased shear stresses in the fluid resulting from the speed differences favor the disintegration into fine droplets near the outlet openings 24. According to the invention, the specific geometry of the outlet openings 24 additionally positively influences the fluid in its atomization, so that a further improved disintegration into very fine droplets can be achieved is.

The perforated disc 23 is produced by means of galvanic metal deposition, wherein the production of the single-layer perforated disc 23 is particularly advantageous with the technique of the so-called lateral overgrowth, which is explained in more detail with reference to FIGS. 5A to 5C.

FIG. 2 shows an enlarged section II in FIG. 1 for clarifying the geometry of the onflow cavity 26 between a boundary surface 30 of the valve seat body 16 and the perforated disk 23 and the geometry of the outlet openings 24 in the perforated disk 23 Valve seat body 16 is configured, for example, such that the boundary surface 30, starting from the outlet opening 27, slopes away from the perforated disc 23 in a radially outwardly inclined manner. As a result, entry planes 31 of the outlet openings 24, which extend perpendicular to the valve longitudinal axis 2, have an ever smaller height of the onflow cavity 26 (decrease in the height of the oncoming cavity 26, for example from 100 μm to 30 μm) and the flow on the way to the radially outer outlet openings 24 is constantly accelerated. The up to four hundred outlet openings 24 are arranged, for example, on a plurality of concentric circular paths in the perforated disc 23. The distances between the individual outlet openings 24 are, for example, about 120 to 150 μm.

The outlet openings 24 ideally have a trumpet-shaped contour, wherein an upstream inflow region 33 has a cylindrical cross-section. The inflow region 33 has a significantly larger diameter than an immediately following opening region of the actual trumpet-shaped outlet opening 24. FIGS. 3 and 4 illustrate two exemplary embodiments of outlet openings 24 formed according to the invention.

In order to get an understanding of the absolute size and the size ratios of the individual sections of the outlet opening 24, some dimensions of the outlet openings 24 will be mentioned below by way of example with reference to FIG. The thickness Hl of the entire perforated disc 23 is about 50 to 100 microns. However, the inflow region 33 of the outlet opening 24 only has a height H2 of approximately 3 to 5 μm. The diameter D1 of the inflow region 33 of the outlet opening 24 is e.g. in the order of about 100 to 150 microns and is thus greater than the thickness Hl of the perforated disc 23. In this diameter-large inflow 33 follows so after about 3 to 5 microns axial length of the

Outlet opening 24 sharp-edged downstream a significantly smaller diameter portion having a diameter D2 of only about 30 to 100 microns. D2 is thus the narrowest diameter of the entire outlet opening 24. Starting from this diameter D2, the outlet opening 24 expands, for example, continuously curved, in particular in a trumpet shape with a constant radius R of the curvature of the wall in the downstream direction. In this way, a diameter D3 at the exit plane 34 of the outlet opening 24 is achieved, which largely corresponds to the diameter D1 of the inlet plane 31 and thus to the inflow region 33 and is therefore also approximately 100 to 150 μm. The exemplary embodiment shown in FIG. 4 differs from the outlet opening 24 illustrated in FIG. 3, above all in that the trumpet-shaped opening region is subdivided into two sections, a first upstream section 35 having a substantially cylindrical contour, while the second downstream section 36 funnel-shaped contour possesses. With a thickness Hl of the perforated disc 23 of approximately 50 to 100 μm, the first cylindrical portion 35 has a length H3 of approximately 20 to 50 μm. The radii R of the curvatures of the walls of both embodiments of the outlet openings 24 are ideally constant and have their center exactly in the lower boundary angle of the inflow 33rd

FIGS. 5A to 5C explain the production steps of the production of the perforated disk 23 according to the invention, in particular in the region of an outlet opening 24. On a substrate body 37, two photoresist layers 38, 39 are deposited on each other. The second lacquer layer 39 is applied only after the masking, exposure and patterning of the first lacquer layer 38. After masking, exposing and patterning the second resist layer 39, both resist layers 38, 39 are developed in one step, i. Unexposed areas of the paint layers 38, 39 are removed by wet-chemical means. There remain on the substrate body 37 at the exposed areas stepped paint towers 40 as remnants of the paint layers 38, 39 are, and precisely at the points where the outlet openings 24 of the perforated disc 23 are to arise. In the first lacquer layer 38, the coater tower 40 has a significantly larger diameter than in the second lacquer layer 39, which, however, is applied at a significantly greater height.

In a next process step (FIG. 5B), metal is electroplated onto the substrate body 37 around the paint towers 40 in a one-step process. The electroplating layer 41 initially grows up from the substrate body 37 on the first lacquer layer 38, and overgrows this first lacquer layer 38 on its surface until the electroplating layer 41 completely touches the circumference of the second lacquer layer 39. The electroplating is stopped at the moment in which a small galvanic layer thickness is present at the periphery of the second lacquer layer 39.

Overgrowing the first lacquer layer 38 results in a desired funnel-shaped or trumpet-shaped indentation in the galvanic layer 41 ("lateral overgrowth") around the second lacquer layer 39 in the region of each paint tower 40. This indentation on each paint tower 40 ultimately forms the strongly diverging part of the respective ones Outlet opening 24 in the perforated disc 23rd After removal of the paint towers 40 ("stripping") and the substrate body 37, there is a single-ply perforated disk 23 with a plurality of outlet openings 24 (Figure 5C). As indicated by the arrow in Figure 5C, the outlet openings 24 of the perforated disk 23 become installed The cylindrical portion 35 of the outlet port 24 shown in Fig. 4 having the narrowest cross section is formed by molding the second resist layer 39 with a high precision.

Claims

claims

1. Fuel injection valve for fuel injection systems of internal combustion engines, with a valve longitudinal axis (2), with a fixed valve seat (29) having valve seat body (16) with a valve seat (29) cooperating valve closing body (7) along the valve longitudinal axis (2) is axially movable, and with a perforated disc (23) arranged downstream of the valve seat (29), which has a multiplicity of outlet openings (24), characterized in that the outlet openings (24) have an inflow area (33) whose diameter D1 is significantly larger is the diameter D2 of a sharp-edged immediately downstream following area, which forms the narrowest cross-section of the outlet opening (24) and from which the outlet opening (24) widens in the flow direction up to a diameter D3.

2. Fuel injection valve according to claim 1, characterized in that the perforated disc (23) has a thickness Hl of about 50 to 100 microns.

3. Fuel injection valve according to claim 1 or 2, characterized in that the inflow region (33) has a height H2 of about 3 to 5 microns.

4. Fuel injection valve according to one of the preceding claims, characterized gekennzeich¬ net, that the inflow region (33) has a diameter Dl of about 100 to 150 microns.

5. Fuel injection valve according to claim 4, characterized in that the outlet opening (24) has its smallest diameter D2 in the sharp-edged transition from the inflow region (33), which is about 30 to 100 microns.

6. Fuel injection valve according to claim 4 or 5, characterized in that the outlet opening (24) widens up to a diameter D3 of about 100 to 150 microns.

7. Fuel injection valve according to one of the preceding claims, characterized in that from the sharp-edged transition of the inflow region (33) from the outlet opening (24) has a trumpet-shaped or funnel-shaped contour.

8. Fuel injection valve according to claim 7, characterized in that the curvature of the wall of the outlet opening (24) extends with a constant radius R.

9. Fuel injection valve according to claim 8, characterized in that the radius R of the curvature of the wall its center in the lower limiting angle of the

Inflow region (33) has.

10. Fuel injection valve according to one of the preceding claims, characterized in that at the inflow region (33) adjoining opening portion is divided into two sections (35, 36), a first upstream portion (35) having a cylindrical contour and a second downstream portion (36) with a funnel-shaped contour.

11. Fuel injection valve according to one of the preceding claims, characterized in that the perforated disc (23) up to four hundred outlet openings (24).

12. Fuel injection valve according to one of the preceding claims, characterized in that an upstream of the perforated disc (23) formed inflow cavity (26) is designed obliquely inclined.

13. Fuel injection valve according to one of the preceding claims, characterized in that the perforated disc (23) can be produced in one layer by means of galvanic metal deposition.