EP1399669A1

EP1399669A1 - Fuel injection valve

Info

Publication number: EP1399669A1
Application number: EP02735017A
Authority: EP
Inventors: Martin Maier; Guenter Dantes; Detlef Nowak; Joerg Heyse
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2001-03-31
Filing date: 2002-03-27
Publication date: 2004-03-24
Anticipated expiration: 2022-03-27
Also published as: DE50206394D1; CZ20023870A3; DE10116186A1; JP2004518896A; EP1399669B1; US6869032B2; WO2002079637A1; KR20030007739A; US20030192965A1

Abstract

The invention relates to a fuel injection valve, especially a high pressure injection valve, for directly injecting fuel into a combustion chamber of a mixture-compressing, spark-injection internal combustion engine. Said fuel injection valve is characterised in that a valve seat element (26) is provided on the downstream end of the valve, a perforated disc (70) used as a flow limiting device being connected downstream from the same. A torsion element (47) is situated upstream of the valve seat (27), the fuel to be injected being displaced in a spray-stimulating rotational movement by means of said torsion element. A longish outlet (32) is embodied downstream from the valve seat (27), in the valve seat element (26), said outlet opening up directly into an opening (73) of the perforated disc (70) fixed to the valve seat element (26). The width of the outlet (32) is larger than the width of the opening (73), at least on the narrowest side thereof, in such a way that the static flow quantity of the valve can be adjusted at the opening (73).

Description

Fuel injector

State of the art

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

From DE-PS 39 43 005 an electromagnetically actuated fuel injection valve is already known, in which several disk-shaped elements are arranged in the seat area. When the magnetic circuit is excited, a flat valve plate, which acts as a flat armature, is lifted from an opposing valve seat plate, which together form a plate valve part. A swirl element is arranged upstream of the valve seat plate, which sets the fuel flowing to the valve seat in a circular rotary movement. A stop plate limits the axial path of the valve plate on the side opposite the valve seat plate. The valve plate is surrounded by the swirl element with great play; the swirl element thus performs a certain guidance of the valve plate. In the swirl element are at the bottom

Several tangential grooves are made on the front side, which extend from the outer circumference to a central swirl chamber. Due to the fact that the swirl element rests with its lower end face on the valve seat plate, the grooves are present as swirl channels. The in the Injection opening introduced into the valve seat plate defines the injection geometry over its length and diameter and must therefore be introduced very precisely.

Furthermore, EP-OS 0 350 885

Fuel injection valve is known, in which a valve seat body is provided, wherein a valve closing body arranged on an axially movable valve needle interacts with a valve seat surface of the valve seat body. Upstream of the valve seat surface, a swirl element is arranged in a recess of the valve seat body, which sets the fuel flowing to the valve seat in a circular rotary movement. A stop plate limits the axial path of the valve needle, the stop plate having a central opening which serves to guide the valve needle to a certain extent. Several tangential grooves are made in the swirl element on its lower face, which extend from the outer circumference into a central swirl chamber. Due to the fact that the lower end face of the swirl element rests on the valve seat body, the grooves are present as swirl channels. In the case of this injection valve, too, the size of the spray opening formed in the valve seat body determines the spray geometry, which is why this spray opening must also be shaped very precisely.

DE-OS 196 07 288 has already described the so-called multilayer electroplating for the production of perforated disks, which are particularly suitable for use on fuel injectors. This

The principle of manufacture of a pane by single or multiple galvanic metal deposition of different structures on one another, so that a one-piece pane is present, is expressly to be included in the disclosure content of the present invention. Advantages of the invention

The fuel injector according to the invention with the characterizing features of the main claim has the advantage that it can be produced inexpensively in a particularly simple manner. It is advantageous to attach the perforated disk provided on the valve seat element very simply and reliably. The perforated disks can be easily and precisely reproduced in large quantities with simple, yet very different opening structures. The perforated disks are components that are very easy to handle in manufacture and fine machining. Since the flow-determining opening cross-section according to the invention also in the perforated disks

A diaphragm function is introduced, advantageously no high demands are placed on the dimensional accuracy of the outlet opening of the valve seat element downstream of the valve seat surface. This makes the valve seat element much easier to handle during its manufacture and processing.

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

It is advantageous that with the very easy to manufacture, handle and assemble perforated disc, which acts as a flow orifice, the static flow rate of the

Valve is adjustable.

It is particularly advantageous to design the perforated disk with a stepped or otherwise cross-sectionally modified opening. The narrowest section of the opening lays then the static flow rate is fixed, while with the remaining length of the opening the spray angle of the sprayed fuel can be influenced in an ideal manner.

If the perforated disc is produced, for example, by means of galvanic metal deposition, arbitrary opening cross sections can be introduced in the simplest way, as a result of which the beam shaping can be designed to be very variable.

Without high demands on the dimensional accuracy of the

The outlet opening of the valve seat element can be adjusted very easily with the exact opening contour of the perforated disc, the static flow rate, the spray angle and the spray shape.

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 first exemplary embodiment of a fuel injection valve, FIG. 2 shows a second example of a fuel injection valve, only the downstream valve end being shown, and FIG. 3 shows a third example of a fuel injection valve in the same view as FIG. 2.

Description of the embodiments

That in Figure 1, for example, as a

Embodiment shown electromagnetically actuated valve in the form of an injection valve for fuel injection systems of spark-ignition internal combustion engines has one as an inner pole of a magnet coil 1 at least partially surrounded Serving magnetic circuit, tubular, largely hollow cylindrical core 2. The fuel injector is particularly suitable as a high-pressure injector for the direct injection of fuel into a combustion chamber of an internal combustion engine. For example, a tiered one

Coil body 3 made of plastic 'takes up the winding of the magnetic coil 1 and, in conjunction with the core 2 and an annular, non-magnetic intermediate part 4 with an L-shaped cross section partially surrounded by the magnetic coil 1, enables a particularly compact and short structure of the injection valve in the region the solenoid 1.

A continuous longitudinal opening 7 is provided in the core 2 and extends along a longitudinal valve axis 8. The core 2 of the magnetic circuit also serves as a fuel inlet connection, the longitudinal opening 7 representing a fuel supply channel. An outer metallic (for example ferritic) housing part 14, which closes the magnetic circuit as an outer pole or outer guide element, and is firmly connected to the core 2 above the magnet coil 1

Magnet coil 1 completely surrounds at least in the circumferential direction. In the longitudinal opening 7 of the core 2, a fuel filter 15 is provided on the inlet side, which ensures that those fuel components are filtered out which, due to their size, cause blockages or blockages in the injection valve

Could cause damage. The fuel filter 15 is, for. B. fixed by pressing in the core 2.

The core 2 forms with the housing part 14 the inlet end of the fuel injector, the upper

Housing part 14, for example, seen in the axial direction downstream, just above the magnetic coil 1 extends beyond. At the upper housing part 14, a lower tubular housing part 18 connects tightly and firmly, which, for. B. an axially movable valve part consisting of an armature 19 and a rod-shaped valve needle ^' l 20 or an elongated valve seat support 21 encloses or receives. The two housing parts 14 and 18 are, for. B. firmly connected to each other with a circumferential weld.

In the embodiment shown in Figure 1, the lower housing part 18 and the largely tubular

Valve seat carrier 21 firmly connected to each other by screwing; Welding, soldering or flanging are also possible joining methods. The sealing between the housing part 18 and the valve seat support 21 is carried out, for. B. by means of a sealing ring 22. The valve seat support 21 has an inner through opening 24 over its entire axial extent, which runs concentrically to the longitudinal axis 8 of the valve.

With its lower end 25, the valve seat carrier 21 surrounds a disk-shaped valve seat element 26 fitted into the passage opening 24 and having a valve seat surface 27 that tapers in the shape of a truncated cone in the downstream direction. B. rod-shaped, a largely circular cross-section valve needle 20 is arranged, which has a valve closing section 28 at its downstream end. This, for example, spherical or partially spherical or rounded or tapered valve closing section 28 interacts in a known manner with the valve seat surface 27 provided in the valve seat element 26. Downstream of the Valve seat surface 27 is introduced in valve seat element 26 at least one outlet opening 32 for the fuel.

The injection valve is actuated electromagnetically in a known manner. A piezo actuator as excitable

Actuating element is however also conceivable. Actuation via a controlled pressure-loaded piston is also conceivable. The electromagnetic circuit with the magnet coil 1, the core 2, the housing parts 14 and 18 and the armature serves to axially move the valve needle 20 and thus to open against the spring force of a return spring 33 arranged in the longitudinal opening 7 of the core 2 or to close the injection valve 19. The armature 19 is with the valve closing section 28 facing away from the end of the valve needle 20 z. B. connected by a weld and aligned to the core 2. For guiding the valve needle 20 during its axial movement with the armature 19 along the longitudinal valve axis 8, on the one hand there is a guide opening 34 provided in the valve seat carrier 21 at the end facing the armature 19 and on the other hand a disk-shaped guide element 35 with an accurate guide opening 55 arranged upstream of the valve seat element 26 19 is surrounded by the intermediate part 4 during its axial movement.

A swirl element 47 is arranged between the guide element 35 and the valve seat element 26, so that all three elements 35, 47 and 26 lie directly on top of one another and are accommodated in the valve seat carrier 21. The three disc-shaped elements 35, 47 and 26 are firmly bonded to one another (weld points or weld seam)

60 in Figures 2 and 3). The stroke of the valve needle 20 is predetermined by the installation position of the valve seat element 26. An end position of the valve needle 20 is determined when the solenoid 1 is not excited by the contact of the valve closing section 28 on the valve seat surface 27 of the valve seat element 26, while the other end position 'of the valve needle 20 when the solenoid coil ^" 1 is excited by the contact of the armature 19 on the results in the downstream end face of the core 2. The surfaces of the components in the latter stop area are chromed, for example.

The electrical contacting of the magnetic coil 1 and thus its excitation takes place via contact elements 43, which are provided outside of the coil former 3 with a plastic encapsulation 44. The

Plastic encapsulation 44 can also extend over further components (eg housing parts 14 and 18) of the fuel injector. An electrical connection cable 45 runs out of the plastic encapsulation 44, via which the energization of the magnet coil 1 takes place.

FIG. 2 shows a second exemplary embodiment of a fuel injection valve, only the downstream valve end being shown. The guide element 35 has a dimensionally accurate inner guide opening 55 through which the valve needle 20 moves during its axial movement. From the outer circumference, the guide element 35 has a plurality of recesses 56 distributed over the circumference, as a result of which a fuel flow on the outer circumference of the

Guide element 35 along into the swirl element 47 and further towards the valve seat surface 27 is guaranteed.

In the example shown in FIG. 2, the valve seat element 26 has a circumferential flange 64 which engages under the stro downward end 25 of the valve seat carrier 21. The upper side 65 of the ^" circumferential flange 64 is ground in one setting with the guide opening 55 and the valve seat surface 27. The three-disc valve body consisting of the elements 35, 47 and 26 is pushed in until the upper side 65 of the flange 64 comes into contact with the end 25 of the Valve seat carrier 21. The valve body is fastened, for example, by a weld seam 61 achieved by means of a laser in the contact area of the two components 21 and 26. The outlet opening 32 is introduced, for example, at an incline to the longitudinal valve axis 8, ending downstream in a protruding spraying area 66.

A thin perforated disk 70 with a specific opening structure is provided on the spray area 66 of the valve seat element 26. This perforated disk 70, which is, for example, sunk in a recess 71 of the spray region 66 of the valve seat element 26 on its downstream end face and is flush with this end face, primarily has the function of a flow orifice. The static flow rate is adjusted via the size of the opening 73. The inner opening 73 of the perforated disk 70 has a smaller opening diameter than the outlet opening 32 of the valve seat element 26. The perforated disk 70 is fastened to the valve seat element 26, for example by means of a weld seam 72; Flanging or fastening with a locking ring are also conceivable. The perforated disk 70 is, for example, with its surface normal below one of 90 ° deviating angle to the longitudinal valve axis 8, so that the angle of the inclination of the outlet opening 32 to the longitudinal valve axis 8 corresponds to that of the opening 73 in the tilted perforated disk 70. In this way, the longitudinal axes of the outlet opening 32 and the opening 73 coincide; Exit opening .32 and opening 73 are therefore aligned. The tubular outlet opening 32 formed in the valve seat element 26 has a greater length than the entire length of the opening 73 of the perforated disk 70, the lengths being, for example, in a ratio of 3 to 10: 1, in the exemplary embodiment shown approximately 5: 1.

In the example shown in FIG. 2, the opening 73 has a continuously cylindrical shape, while in the embodiment according to FIG. 3 a stepped opening 73 is provided. The opening 73 of the perforated disk 70 according to FIG. 3 has a narrower upstream section 75 and a further downstream section 76. At least the narrower section 75 has a smaller opening diameter than the outlet opening 32 of the

Valve seat element 26. While the narrower section 75 of the opening 73 defines the static flow rate, the somewhat enlarged section 76 can ideally influence the spray angle of the sprayed fuel.

The perforated disks 70 can be produced in a very simple, reproducible manner in large numbers with simple and nevertheless very different opening structures. Since, according to the invention, the flow-determining opening cross-section with a diaphragm function is introduced into the perforated disks 70, high demands on the dimensional accuracy are advantageously not made of the outlet opening 32 of the valve seat element 26 downstream of the valve seat surface 27. Thus, the valve seat member 26 much easier to handle during its manufacture and processing.

The perforated disk 70 is ideally so-called galvanic metal deposition, in particular the

Multilayer electroplating manufactured. Selecting the perforated disk 70 according to FIG. 2 from a single-layer metal layer, the exemplary embodiment according to FIG. 3 shows a perforated disk 70 which comprises two layers, one layer each being characterized by a constant inner opening contour 75, 76 which changes in the next layer is. A two-layer perforated disk 70 can be produced, for example, by metal deposition of two layers on top of one another, the two layers then being bonded to one another and ultimately forming a component. With this technology, shapes of openings 73 can also be produced in the perforated disks 70 which deviate from a circular contour and e.g. are triangular to n-square or shamrock-like, etc. In this way, very different jet shapes can be easily generated with a perforated disk 70 designed in this way.

Due to the deep lithographic, galvanotechnical production, there are special features in the contouring, some of which are summarized below:

- layers with constant thickness over the pane surface,

- Due to the deep lithographic structuring, largely vertical incisions in the layers, which form the cavities through which they 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.

On the other hand, however, it is also conceivable to manufacture the perforated disks 70 by punching and embossing, eroding or etching. For example, the opening contour can also be inserted very precisely in a steel sheet by means of laser beam drilling, eroding or punching.

Claims

Expectations

1. Fuel injection valve for fuel injection systems of internal combustion engines, in particular for direct injection of fuel into a combustion chamber of an internal combustion engine, with a longitudinal valve axis (8), with an actuator (1, 2, 14, 18, 19), with a movable valve part (20), which cooperates to open and close the valve with a fixed valve seat (27) which is formed on a valve seat element (26), with a swirl element (47) arranged upstream of the valve seat (27), and with a downstream of the valve seat (27) in Valve seat element (26) designed outlet opening (32), characterized in that the outlet opening (32) opens directly into exactly one aligned opening (73) of a perforated disc (70) attached to the valve seat element (26), both the length of the outlet opening (32) of the valve seat element (26) in the flow direction is greater than the length of the opening (73) of the perforated disc (70) and the opening width ite the outlet opening (32) is greater than the opening width of the opening (73) at least at its narrowest point.

2. Fuel injection valve according to claim 1, characterized in that the opening (73) of the perforated disc (70) has a circular cross-section and runs with a constant opening width over its entire length. is.

3. Fuel injection valve according to claim 1, characterized in that the opening (73) of the perforated disc (70) is stepped and is thus designed to be variable in its opening width over its length.

4. Fuel injection valve according to claim 3, characterized in that the narrowest opening width of the opening (73) in the perforated disc (70) faces the outlet opening (32) and the opening width becomes larger in the downstream direction.

5. Fuel injection valve according to one of the preceding claims, characterized in that the static flow rate of the valve is adjustable with the narrowest cross section of the opening (73).

6. Fuel injector according to one of the preceding

Claims, characterized in that the outlet opening (32) extends obliquely to the longitudinal valve axis (8).

7. Fuel injection valve according to one of the preceding claims, characterized in that the perforated disc (70) has a surface normal and the perforated disc (70) is fastened to the valve seat element (26) in such a way that the surface normal is at an angle deviating from 90 ° to the longitudinal valve axis (8 ) runs.

8. Fuel injection valve according to one of the preceding claims, characterized in that a recess (71) is provided on the downstream end face of the valve seat element (26), in which the perforated disc (70) is introduced.

9. The fuel injector according to claim 8. characterized in that the perforated disc (70) is completely sunk in the recess (71) and is flush with the downstream end face of the valve seat element (26) in this area.

10. Fuel injection valve according to one of the preceding claims, characterized in that the perforated disc (70) can be produced by means of galvanic metal deposition.