EP1875067A1

EP1875067A1 - Fuel-injection valve

Info

Publication number: EP1875067A1
Application number: EP06708262A
Authority: EP
Inventors: Stefan Arndt; Markus Gesk; Guenter Dantes; Joerg Heyse; Andreas Krause; Kai Gartung
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2005-04-15
Filing date: 2006-02-14
Publication date: 2008-01-09
Also published as: US20090206181A1; JP2008536049A; DE102005017420A1; WO2006108729A1; BRPI0605913A2

Abstract

The invention relates to a fuel-injection valve, which is characterised in that an injection orifice plate (23) is located downstream of a valve seat body (16) comprising a fixed valve seat (29), said plate having at least one outlet opening (24). An inflow opening (19) comprising an annular inlet cavity (26) is provided directly upstream of the outlet openings (24). The valve seat body (16) protects the inlet cavity (26) in such a way that the downstream outlet openings (24) of the injection orifice plate (23) are covered. The inlet cavity (26) that lies directly upstream of the outlet opening(s) (24) is configured in such a way that fuel essentially streams towards the outlet opening (24) at a right angle to the longitudinal extension of the outlet opening (24). The cross-section of the outlet opening(s) (24) is configured as a polygon, in particular with a triangular shape, or has an undulating shape with several arcs along its external contour. The fuel-injection valve is particularly suitable for use in the fuel-injection systems of compressed-mixture, 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, wherein the outlet openings define even the narrowest flow cross-section.

From US Pat. No. 6,405,946 B1, a fuel injection valve is already known in which a perforated disk 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 outlet openings have a round or elliptical cross section.

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 outlet openings are provided downstream of a valve seat, which are flowed horizontally and are contoured so that the circumference of the outlet opening is maximized in relation to the cross section of the outlet opening. The horizontal velocity components of the flow entering the entry plane are not obstructed by the wall of the respective outlet opening at the entry plane, so that the fuel jet has the full intensity of the horizontal components generated in the onflow cavity when exiting the exit opening and therefore fanning with maximum atomization. Due to the horizontal flow of the outlet openings, the flow in the outlet openings is directional diffusional due to vortex formation. The instant fanning avoids the liquid surface tension from contracting the emergent jet to a cylindrical jet of smaller free surface. The increased free radiation surface favors the further disintegration into smaller droplets.

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 outlet openings an inflow opening is provided with an annular inflow cavity, which is larger 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 disc. In a particularly advantageous manner, the formation of the inflow opening an S-blow in the flow for atomization improvement of the fuel reaches, since the valve seat body with the upper boundary of the inflow opening covers the outlet openings of the perforated disc.

By means of electrodeposition, 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 method of manufacture allows a great freedom of design in the contouring of the outlet openings in the perforated disc.

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 the inventively designed area in an enlarged view, Figure 3 shows a first embodiment of a

Figure 6 shows a third embodiment of an outlet opening, Figure 6 shows a fourth embodiment of an outlet, Figure 7 shows a fifth embodiment of an outlet, Figure 8 shows a sixth embodiment of an outlet and Figure 9 shows a seventh embodiment of an outlet.

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. spherical valve-closing body 7, at the periphery of which, 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 for opening against the spring force of a return spring, not shown, or closing of the injection valve is used The armature 11 is connected to the valve closing body 7 facing away from the end of the valve needle 5 by, for example, a trained by a laser weld and aligned with the core 12. Die Anker 11 ist mit dem Elektromagnet 11 verbunden ,

In the downstream end of the valve seat carrier 1 is a valve seat body 16, e.g. tightly assembled by welding. At its lower end face 17 facing away from the valve closing body 7, the valve seat body 16 is stepped, with a recess 20 being provided in a central area around the valve longitudinal axis 2, in which a flat, e.g. single-layer perforated disc 23 is introduced. The perforated disc 23 has at least one, but ideally two to forty outlet openings 24. 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 into the inflow opening 19 and ultimately into the outlet openings 24.

The inflow opening 19 is designed in the immediate onflow region of the outlet openings 24 in such a way that the flow reaches the outlet openings 24 substantially at right angles to the longitudinal extension of the outlet openings 24, ie horizontally in FIG. 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, explained in more detail on the basis of this figure, 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 longitudinal opening 3 determines the size of the stroke of the valve needle 5, since the one end position of the valve needle 5 at 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 when the solenoid 10 is energized, for example determined by the plant 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.

Due to 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 resulting from the differences in speed increased shear stresses in the fluid favor the disintegration into fine droplets near the outlet openings 24. According to the invention the fluid is additionally positively influenced in its atomization by the specific geometry of the outlet openings 24 in connection with the horizontally approachable Anströmhohlraum 26, so that a even further improved decay in the finest droplets can be achieved.

The perforated disk 23 is produced, for example, by means of galvanic metal deposition, wherein the production of a single-layer perforated disk 23 is advantageous, in particular with the technique of lateral overgrowth. Instead of a single-layer perforated disk 23, it is also possible to use a multi-layer perforated disk 23 in which, for example, the Anströmhohlraum 26 is directly integrated. The outlet openings 24 ideally have a trumpet-shaped contour. From the cross section, the outlet openings 24 are formed with a polygonal shape, in particular a form comprising at least one triangle, or with a meandering shape having a plurality of arcs in the outer contour.

FIG. 2 shows an enlarged detail II in FIG. 1 for clarifying the geometry of the onflow cavity 26 between the outlet opening 27 and the perforated disk 23. The valve seat body 16 is configured in such a way that the onflow cavity 26 of the inflow opening 19 starting from the Austrittsöffiiung 27 above the perforated disc 23 extends radially outwardly very flat. The inflow lumen 26 ideally extends radially outward beyond the outlet ports 24. As a result, above all each Auslassöffiiung 24 also backspace side fed with a significant flow rate component. As a back space 33 of the radially outward of the respective Auslassöffiiung 24 lying region of the

Anströmhohlraums 26 understood. Consequently, the lateral velocity vectors are divergent at the exit of the outlet ports 24 and provide good atomization of the fuel.

FIGS. 3 to 9 show seven exemplary embodiments of outlet openings 24 according to the invention. Advantageously, the outlet openings 24 are contoured such that the circumference of the outlet opening 24 is maximized in relation to the cross section of the outlet opening 24. The cross-sectional shape of a fluid jet emerging from an outlet opening 24 largely corresponds to the cross-sectional shape of the outlet opening 24. The free surface of a jet emerging from an outlet opening 24 is correspondingly large in relation to its sprayed off liquid quantity. By the entrance to levels 31 of the

Outlet openings 24 horizontal flow of the outlet openings 24, the flow in the outlet openings 24 direction diffusely, i. the exiting fluid jet fanning out immediately after leaving the outlet opening 24. The instant fanning avoids the liquid surface tension from contracting the emergent jet to a cylindrical jet of smaller free surface. The increased free radiation surface favors the further disintegration into smaller droplets.

FIGS. 3 and 4 show two star-shaped outlet openings 24. These outlet openings 24 have e.g. five prongs 35, each having a triangular contour in itself. The number of pips 35 and their format, so theirs

Length a or width b are freely selectable. The star-shaped outlet opening 24 can either be aligned so that a depression between two prongs 35 is directed radially directly onto the valve longitudinal axis 2 or the center of the perforated disk 23 (FIG. 3) or that a prong 35 with its tip extends radially directly onto the valve longitudinal axis 2 or the center of the perforated disc 23 shows (Figure 4). On the one hand, the arrows 32 are intended to indicate that the inflow of the outlet openings 24 is horizontal to their entry planes 31 or substantially at right angles to the longitudinal extent of the outlet openings 24 and, on the other hand, to indicate how the outlet opening 24 is aligned with the valve longitudinal axis 2. FIGS. 5 and 6 show two star-shaped outlet openings 24. These outlet openings 24 have, for example, four prongs 35, each of which has a triangular contour in its own right. The number of prongs 35 and their format, so their length a or width b are arbitrary. The star-shaped outlet opening 24 may be either aligned so that a recess between two prongs 35 radially directly on the

Valve longitudinal axis 2 or the center of the perforated disc 23 is directed (Figure 5) or that a tine 35 with its tip radially directly on the valve longitudinal axis 2 and the center of the perforated disc 23 shows (Figure 6). On the one hand, the arrows 32 are intended to indicate that the inflow of the outlet openings 24 is horizontal to their entry planes 31 or substantially at right angles to the longitudinal extent of the outlet openings 24 and, on the other hand, to indicate how the outlet opening 24 is aligned with the valve longitudinal axis 2.

In FIGS. 7 and 8, two triangular outlet openings 24 are shown. In cross-section, the outlet opening 24 has e.g. the shape of an equilateral triangle. The outlet opening 24 is to be regarded as a tine 35. Such a cross-sectional shape also favors the generation of vortices in the outlet opening 24. The swirling movements within the outlet opening 24 induced due to the horizontal flow are schematically drawn in and identified by the reference numeral 36.

FIG. 9 shows a further exemplary embodiment of an outlet opening 24 in cross-section. This outlet opening 24 is formed with a plurality of arcs 35 'in the outer contour having meander-like shape.

The perforated disc 23 can be manufactured by microgalvanic, laser cutting, etching or punching technology. The cross section of the outlet openings 24 is depending on

Production method or use request over the entire length of the outlet openings 24 constant or increasing in the flow direction, as shown in Figures 1 and 2. In the area of the entry levels 31, the outlet openings 24 have a clear opening width of e.g. at least 30 microns.

Claims

claims

1. Fuel injection valve for fuel injection systems of internal combustion engines, having 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 at least one outlet opening (24), wherein a Anströmhohlraum (26) immediately upstream of the at least one outlet opening (24) is designed so that a flow the at least one outlet opening (24) takes place largely at right angles to the longitudinal extent of the outlet opening (24), characterized in that the at least one outlet opening (24) with a polygonal shape, in particular a shape comprising at least one triangle, or with a a plurality of bends (35 ') in the outer contour having meandering shape a is educated.

2. Fuel injection valve according to claim 1, characterized in that the Anströmhohlraum (26) is the annular outer region of an inflow opening (19) which is provided between an outlet opening (27) of the valve seat body (16) and the perforated disc (23).

3. Fuel injection valve according to claim 2, characterized in that there is a complete offset between the outlet opening (27) and the at least one outlet opening (24).

4. Fuel injection valve according to one of the preceding claims, characterized in that the Anströmhohlraum (26) extends radially outwardly beyond the at least one outlet opening (24) with a rear space (33).

5. Fuel injection valve according to one of the preceding claims, characterized in that the at least one outlet opening (24) has the shape of an equilateral triangle in cross section.

6. Fuel injection valve according to one of claims 1 to 4, characterized in that the at least one outlet opening (24) in cross-section is star-shaped.

7. Fuel injection valve according to claim 6, characterized in that the star-shaped outlet opening (24) has a plurality of triangular prongs (35).

8. Fuel injection valve according to one of the preceding claims, characterized in that the at least one outlet opening (24) has a trumpet-shaped contour.

9. Fuel injection valve according to one of the preceding claims, characterized in that the perforated disc (23) by means of galvanic metal deposition, laser cutting technology or punching technology can be produced.

10. Fuel injection valve according to one of the preceding claims, characterized in that in the perforated disc (23) between two and forty outlet openings (24) are provided.