EP1009931A1

EP1009931A1 - Fuel injection valve

Info

Publication number: EP1009931A1
Application number: EP99910101A
Authority: EP
Inventors: Bo Yuan; Günter DANTES; Jörg HEYSE
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1998-05-22
Filing date: 1999-02-05
Publication date: 2000-06-21
Anticipated expiration: 2019-02-05
Also published as: JP2002516956A; DE59908299D1; EP1009931B1; US20020060257A1; DE19822896A1; WO1999061787A1; KR20010014189A

Abstract

The inventive fuel injection valve is characterised in that a perforated disk (23) is arranged downstream from the surface of a valve seat (29) pertaining to a valve seat body (16), whereby said disk is held by a flat disk-shaped perforated-disk carrier (21) on the body (16) of the valve seat. The perforated disk comprises a full opening area for a fluid and at least one inlet on an upper functional level or layer in addition to at least one outlet on a lower functional level or layer. The perforated-disk carrier (21) has a through opening (20) that is directly surrounded by an edge area (35) which is provided with recesses that reduce the elastic rigidity of said disk carrier (21).

Description

Fuel injector

State of the art

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

From DE-OS 196 39 506 is already a

Fuel injector known to the one

Has valve seat body with a valve seat surface and a perforated disc carrier attached to the valve seat body. The perforated disc carrier is used to hold a multi-layer perforated disc, manufactured using multilayer electroplating, firmly and securely on the valve seat body by clamping. For this purpose, the perforated disc carrier is flat and disk-shaped, has an overall pot-shaped structure and a constant thickness over its entire extent. The perforated disk carrier is fastened to the valve seat body with the aid of an annular circumferential weld seam. When the perforated disk carrier is welded on, however, the clamping force of the perforated disk carrier with which the perforated disk is pressed against the valve seat body decreases. This is due to the thermal relaxation of the prestressed material of the perforated disc carrier. In the area of the weld seam there is also an air gap between the Valve seat body and the perforated disc carrier, which reduces the quality of the weld seam and reduces the clamping effect.

Perforated disc carriers, support discs, support rings or

Retaining nuts for perforated disks of injection valves or nozzles are e.g. also already known from GB-PS 201,556, DE-OS 41 23 692, DE-OS 44 46 241 or DE-OS 195 27 626, but no measures have been taken to improve the clamping effect by varying the spring stiffness.

Advantages of the invention

The fuel injector according to the invention with the characterizing features of claim 1 has the advantage that a particularly high quality of the attachment point of the perforated disc carrier to the valve seat body is achieved, which in turn has the result that a very good holding effect of the perforated disc carrier on the perforated disc is achieved, which also is hardly or not at all affected by the fastening of the perforated disc carrier.

For this purpose, the perforated disk carrier is provided in an edge region surrounding a through opening, which is used directly for holding (clamping) the perforated disk, with moldings which reduce the spring rigidity of the perforated disk carrier. Taking tolerances into account when determining the limiting diameter for the specially shaped edge area, it is ensured that the fastening point (weld seam) is always attached outside the edge area of the perforated disc carrier.

In the edge area of the through opening, the spring stiffness of the perforated disc carrier is thinned out or slits deliberately reduced, so that when the perforated disc carrier is pressed onto the valve seat body before welding, it is mainly this less rigid edge area that bends. In the area of the weld seam, the preload is thus reduced compared to known designs. In addition, the perforated disk carrier already lies largely without an air gap on the lower end face of the valve seat body in the area of the weld seam to be set, which reduces the thermal relaxation in the weld seam area. Because of this, the clamping effect of the perforated disk carrier on the perforated disk remains very well preserved even after welding.

The measures listed in the subclaims allow advantageous developments and improvements of the fuel injector specified in the main claim.

In a particularly advantageous manner, the formations in the edge region of the through opening are formed by thinning out or introducing slots. The perforated disc carrier is thinned out in such a way that an annular step is formed by embossing either from the upper or from the lower end face.

It is particularly advantageous to use perforated disks which are produced by galvanic metal deposition and are made in one piece, the individual functional levels or layers being built up on one another in directly successive deposition process steps. After completing the

Metal perforation is in one piece of the perforated disc; no time-consuming and costly process steps for connecting individual nozzle plates are therefore necessary. It is particularly advantageous to design the perforated disks in the form of so-called S-type disks (S-shaped flow course within the disk) in order to be able to produce extraordinary bizarre jet shapes. It is optimal for an S-type disc if there is an offset between the inlet openings and the outlet openings. The unusual beam shapes that can be created allow an exact optimal adaptation to given geometries, e.g. B. to different intake manifold cross sections of internal combustion engines. This results in the advantages of a shape-adapted utilization of the available cross-section for the homogeneously distributed, exhaust-reducing mixture introduction and the avoidance of emissions-harmful wall film deposits on the intake manifold wall.

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 with a first fastening according to the invention of a perforated disk with a perforated disk carrier, FIG. 2 shows a second example of such a fastening at the valve end, FIG. 3 shows a top view of the edge region of the perforated disk designed with an anti-rotation device in FIG. 2, FIG. 4 third example of fastening a perforated disk with a perforated disk carrier at the valve end, FIG. 5 shows a fourth example of such a fastening at the valve end, FIG. 6 shows a detail from FIG. 5 with a one obtained by caulking

7, a further perforated disk carrier in section and FIG. 8 the perforated disk carrier according to FIG. 7 in a plan view. Description of the embodiments

1 shows, as an exemplary embodiment, a valve in the form of an injection valve for fuel injection systems of mixed-compression spark-ignition internal combustion engines. The injection valve has a tubular valve seat support 1, in which a longitudinal opening 3 is formed concentrically with a valve longitudinal axis 2. In the longitudinal opening 3 is a z. B. tubular valve needle 5 arranged at its downstream end 6 with a z. B. spherical valve closing body 7, on the circumference of which, for example, five flats 8 are provided for the fuel to flow past, is firmly connected.

The injection valve is actuated in a known manner, for example electromagnetically. A schematically indicated electromagnetic circuit with a solenoid 10, an armature 11 and a core 12 is used for the axial movement of the valve needle 5 and thus for opening against the spring force of a return spring (not shown) or closing the injection valve. The armature 11 is connected to the valve closing body 7 opposite end of the valve needle 5 by z. B. a weld seam connected by a laser and aligned with the core 12.

To guide the valve closing body 7 during the axial movement, a guide opening 15 of a valve seat body 16 is used, which is tightly mounted by welding in the downstream end of the valve seat carrier 1, which is remote from the core 12, in the longitudinal opening 3, which runs concentrically to the longitudinal axis 2 of the valve. On its lower end face 17 facing away from the valve closing body 7, the valve seat body 16 is provided with a z. B. cup-shaped and serving as a retaining ring perforated disc carrier 21 concentrically and firmly connected, which thus lies at least with an outer ring region 22 directly on the valve seat body 16. The perforated disk carrier 21 has a shape similar to that of well-known cup-shaped spray perforated disks, a central region of the perforated disk carrier 21 being provided with a through opening 20 without a metering function.

A perforated disc 23, e.g. in the form of a one-piece but multilayer so-called multilayer electroplating

Spray plate is formed, is arranged upstream of the through opening 20 such that it completely covers the through opening 20. The perforated disc carrier 21 is designed with an inner base part 24 and an outer holding edge 26. The holding edge 26 extends in the axial direction facing away from the valve seat body 16 and is conically bent outwards up to its end. The bottom part 24 is from the outer ring area

22 and the central through opening 20 are formed.

The valve seat body 16 and the perforated disk carrier 21 are connected, for example, by a circumferential and sealed first weld seam 25 formed by a laser. This type of assembly increases the risk of undesired deformation of the

Perforated disk carrier 21 avoided in its central region with the through opening 20 and the perforated disk 23 arranged upstream there. The perforated disk carrier 21 is further connected in the region of the holding edge 26 to the wall of the longitudinal opening 3 in the valve seat carrier 1, for example by a circumferential and tight second weld seam 30.

The perforated disk 23 which can be clamped in the area of the passage opening 20 within the circular weld seam 25 between the perforated disk carrier 21 and the valve seat body 16 is, for example, staged. An upper perforated disk area 33, which has a smaller diameter than a base area 32, protrudes into a cylindrical outlet opening 31 of the valve seat body 16 following a valve seat surface 29. For this

A press fit can also be provided in the area of the perforated disk area 33 / outlet opening 31. The radially protruding beyond the perforated disk area 33 and thus clampable base area 32 of the perforated disk 23 rests on the lower end face 17 of the valve seat body 16, so that at this point the bottom part 24 of the perforated disk carrier 21 lies at a short distance from the end face 17. During the perforated disc area 33 z. B. two functional levels, namely a middle and an upper functional level, the perforated disc 23, a lower functional level forms the base area 32 alone. A functional level should have a largely constant opening contour over its axial extent.

According to the invention, the perforated disc carrier 21 is thinned out in the edge region 35 of its central through opening 20, which is to mean that the perforated disc carrier 21 in the edge region 35 of the through opening 20 has at least partially a smaller thickness than over its further extent (ring region 22, holding edge 26). In the example shown in FIG. 1, the perforated disk carrier 21 is thinned out in its area lying within the weld seam 25 towards the through opening 20 to the extent that the edge area 35 is only approximately half as thick as the rest of the perforated disk carrier 21. A step 38 is provided on the lower end face 36 of the perforated disk carrier 21 facing away from the end face 17 of the valve seat body 16 in order to form the thinner edge region 35. The thinned or weaker edge region 35 serves directly the clamping of the perforated disk 23. The contour of the edge region 35 is achieved, for example, by embossing.

Taking tolerances into account when determining the limiting diameter for the thinned edge region 35, it is ensured that the weld seam 25 is always applied in the thicker region of the perforated disc carrier 21. In the edge area 35, the spring stiffness of the perforated disk carrier 21 is specifically reduced by the thinning out, so that when the perforated disk carrier 21 is pressed onto the valve seat body 16, this thinned edge area 35 mainly bends before welding. In the area of the weld seam 25, the pretension is thus reduced with a constant thickness compared to known constructions. In addition, the

Perforated disk carriers 21 in the area of the weld seam 25 to be set already largely without an air gap at the lower end face 17 of the valve seat body 16, which reduces the thermal relaxation in the weld seam area 25. Because of this, the clamping effect remains on the

Perforated disc 23 in very good condition even after welding.

The insertion depth of the valve seat part consisting of valve seat body 16, cup-shaped perforated disk carrier 21 and perforated disk 23 into 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 when the solenoid coil 10 is not excited due to the valve closing body 7 resting on the valve seat surface 29 of the valve seat body 16 is fixed. The other end position of the valve needle 5 is determined when the solenoid 10 is excited, for example by the armature 11 resting on the core 12. The path between these two end positions of the valve needle 5 thus represents the stroke. The spherical valve closing body 7 acts with the conical frustum in the direction of flow Valve seat surface 29 of the valve seat body 16 together, which is formed in the axial direction between the guide opening 15 and the lower outlet opening 31 of the valve seat body 16.

The perforated disk 23, which is arranged in the outlet opening 31 of the valve seat body 16 and is also held directly on the end face 17 of the valve seat body 16 by the perforated disk carrier 21, is only shown in simplified form and as an example in FIG. Instead of the perforated disk 23 shown, other embodiments of perforated disks with different opening geometries and outer contours can also be fastened according to the invention with a perforated disk carrier 21 shaped according to the invention. Such restraint as indirect

Fastening the perforated disk 23 to the valve seat body 16 has the advantage that temperature-related deformations are avoided, which could possibly occur in processes such as welding or soldering with a direct attachment of the perforated disk 23.

The perforated disks 23 shown in FIGS. 1 to 6 are built up in several metallic functional levels by means of galvanic deposition (multilayer electroplating). Because of the deep lithographic, galvanotechnical

Manufacturing there are special features in the contouring, some of which are summarized below:

- functional levels with constant thickness over the pane surface,

- through the deep lithographic structuring, largely vertical incisions in the functional levels, which form the respective cavities through which flow (production-related deviations of approx. 3 ° compared to optimally vertical walls can occur), - desired undercuts and overlaps of the incisions due to the multi-layer structure of individually structured metal layers,

Incisions with any cross-sectional shapes that have largely axially parallel walls,

- One-piece design of the perforated disc, since the individual metal deposits take place directly on top of one another.

The process steps of galvanic metal deposition for the production of a perforated disk have already been described in detail in DE-OS 196 07 288 and are intended to be part of the disclosure content here.

In the further exemplary embodiments of the following figures, the parts that remain the same or have the same effect as the exemplary embodiment shown in FIG. 1 are identified by the same reference numerals. FIG. 2 shows a second exemplary embodiment of a perforated disk 23 clamped with a perforated disk carrier 21. The perforated disk 23 is again a flat, circular one

Component executed that has several, for example three, axially successive functional levels or galvanically deposited layers. While the two lower functional levels or layers built up first form a perforated disk area 33 with the same outside diameter, the upper and last built-up functional level of the perforated disk 23 is designed with a larger outside diameter, so that an externally projecting clamping area 34 is formed. At least one inlet opening is provided in the upper functional level, while in the lower

Functional level at least one outlet opening is formed, which are connected to each other so that there is a complete axial passage for the fuel. The edge region 35 of the perforated disc carrier 21 towards the through opening 20 is again thinned out in order to achieve the advantages already described due to the reduced spring stiffness. In contrast to the first exemplary embodiment, the edge region 35 is thinned out from the upper end face 37 of the perforated disk carrier 21, that is to say it is provided with a step 38 which is achieved, for example, by embossing. The gap in the edge area 35 formed due to the thinning in the case of the perforated disk carrier 21 lying against the valve seat body 16 has, for example, exactly an axial extent which corresponds to the axial thickness of the upper layer of the perforated disk 23 or its clamping area 34. The edge area 35 thus engages under the radially projecting clamping area 34 of the perforated disk 23. The perforated disk 23, which is clamped to the exact dimension, also extends with its lower perforated disk area 33 exactly through the through opening 20 of the perforated disk carrier 21.

Before the weld seam 25 is applied, the perforated disk 23 is already pre-assembled in the perforated disk carrier 21. The perforated disk 23 can already be fixed exactly in the perforated disk carrier 21 by pressing, caulking, flanging or gluing.

FIG. 3 shows a top view of the edge region 35 of the perforated disk 23 in FIG. 2, which is designed with an anti-rotation device. In order to prevent the perforated disk 23 from rotating in the installed state and to guarantee a clear installation position due to the specific opening geometry, a simple anti-rotation device can optionally be provided , which is ensured, for example, by attaching corresponding flats 39, 39 'to the clamping area 34 of the perforated disk 23 and to the perforated disk carrier 21. FIG. 4 shows a mixed form of the exemplary embodiments already explained. The perforated disk 23 used in the example according to FIG. 4 largely corresponds to that of FIG. 1; The perforated disk carrier 21 largely corresponds to that of FIG. 2. The perforated disk region 33, consisting of the upper functional levels or layers of the perforated disk 23, protrudes through the through opening 20 of the perforated disk carrier 21, similar to the second exemplary embodiment. The lower basic area, which is designed with a larger outer diameter than the perforated disk region 33 32 of the perforated disk 23 engages under the edge region 35 of the perforated disk carrier 21. Since the perforated disk 23 is not clamped with the edge region 35 of the perforated disk carrier 21, the perforated disk 23 must be secured by pressing in, caulking, flanging or gluing or possibly even by soldering or Welding done on the perforated disc carrier 21.

FIG. 5 shows an installation variant in which the perforated disk 23 shown in FIG. 1 is used. With its upper perforated disk area 33, the perforated disk 23 projects into the outlet opening 31 of the valve seat body 16 with exact dimensions. To clamp the lower base area 32 of the perforated disk 23 by the perforated disk carrier 21, the latter is designed in the version of FIG. 2, that is to say with a thinning (step 38) provided in the edge area 35 from the upper end face 37. The gap in the edge region 35, which is formed due to the thinning, when the perforated disc carrier 21 is in contact with the valve seat body 16, in turn has, for example, exactly an axial extent which corresponds to the axial thickness of the clamped lower layer of the perforated disc 23 or its base region 32. FIG. 6 shows a detail from FIG. 5 with a perforated disk 23 which has been secured by caulking. After the perforated disk carrier 21 has been welded to the valve seat body 16, it is possible to provide an anti-twist device to ensure a safe and defined installation position of the perforated disk 23. This can be produced very simply by caulking the edge region 35 of the perforated disc carrier 21 at one point, for example, with a stem-shaped tool 40. Material is shifted to a small extent in such a way that slipping or twisting of the perforated disk 23 is excluded. The anti-rotation device can also be achieved in that, for example, a laser point is set in the region of the caulking shown in FIG. 6, by means of which the perforated disk 23 is fixed in the outer base area 32 on the perforated disk carrier 21.

Another embodiment of a perforated disc carrier 21 is shown in FIGS. 7 and 8. The inventive reduction of spring stiffness in

The edge region 35 of the perforated disc carrier 21 is not achieved here by thinning out, but rather by introducing a plurality of radially running slots 42. The slots 42 are arranged largely in a star shape and are in direct connection with the through opening 20.

All versions of the perforated disc carrier 21 can be manufactured by punching, embossing and forming. The thinning of the edge area 35 is e.g. achieved by embossing, the central through opening 20 after the

Embossing is punched out. Alternatively, the through opening 20 can first be punched, and while the punch is in the through opening 20, the embossing stamp for embossing the edge region 35 can be added.

Claims

claims

1.Fuel injection valve for fuel injection systems of internal combustion engines, with a valve longitudinal axis, with a valve closing body, which cooperates with a valve seat surface associated with a valve seat body, with a perforated disk downstream of the valve seat surface, the perforated disk providing a complete passage for a fluid and at least one inlet opening in an upper functional level or . Layer and at least one outlet opening in a lower functional level or layer, and with a disc-shaped perforated disc carrier, which is fixedly connected to the valve seat body and through which the perforated disc is held on the valve seat body, and the perforated disc carrier has a through opening, characterized in that the Perforated disk carrier (21) is provided in an edge region (35) surrounding the through opening (20) with shapes that reduce the spring stiffness of the perforated disk carrier (21).

2. Fuel injection valve according to claim 1, characterized in that the formation in the edge region (35) is designed as an annular circumferential step (38).

3. Fuel injection valve according to claim 2, characterized in that the step (38) from an upper, the valve seat body (16) facing end face (37) of the perforated disc carrier (21) is introduced.

4. Fuel injection valve according to claim 2, characterized in that the step (38) from a lower, the valve seat body (16) facing away from the end face (36) of the perforated disc carrier (21) is introduced.

5. Fuel injection valve according to claim 1, characterized in that the formations in the edge region (35) as a plurality of slots extending from the through opening (20)

(42) are formed.

6. Fuel injection valve according to claim 5, characterized in that the slots (42) run radially in a star shape.

7. Fuel injection valve according to one of the preceding claims, characterized in that the perforated disc (23) has at least two axially successive areas (32, 33, 34) of different outer diameters.

8. Fuel injection valve according to claim 7, characterized in that the region (32, 34) of larger diameter of the perforated disc (23) is clamped between the edge region (35) of the perforated disc carrier (21) and the valve seat body (16).

9. Fuel injection valve according to claim 7 or 8, characterized in that the region (33) of smaller diameter of the perforated disc (23) extends completely through the through opening (20) of the perforated disc carrier (21).

10. Fuel injection valve according to one of the preceding claims, characterized in that the perforated disc (23) is arranged against rotation in the perforated disc carrier (21).

11. Fuel injection valve according to one of the preceding claims, characterized in that the perforated disc (23) can be produced by means of multilayer electroplating by building up a plurality of electrodeposited layers.