EP1339973B1 - Atomising disc and fuel injection valve with an atomising disc - Google Patents

Description

State of the art

The invention relates to an atomizer disk according to the preamble of claim 1 and of a fuel injection valve with a spray disk according to the preamble of claim 11.

Et al From DE-OS 196 39 506 an electromagnetically operable fuel injection valve is already known, in which a atomizer disk is provided downstream of a valve seat. This atomizer disk is used for fuel processing and metered injection of a molded fuel spray.

From a variety of publications regarding nozzles and injectors to internal combustion engines, but also inkjet printers, nozzles for spraying fluids of any kind or inhalers a variety of design variants of atomizer discs are already known. These are usually characterized by at least one inlet and at least one outlet and a certain connection distance between inlet and outlet, which can be very short, for a complete Passage of a fluid. The opening geometries are flow-determining and have a metering function. Targeted contouring (eg swirl disks, offset disks with outlet offset from the inlet, multi-jet disks) for the fuel injection valve, in particular with the use of atomizer disks on fuel injection valves, can achieve the advantages of a high spray quality, uniform atomization and a high variability in jet shapes.

From US 5,716,001 A, a fuel injection valve for fuel injection systems of internal combustion engines with an actuator is known, which also has a movable valve member which cooperates to open and close the valve with a fixed valve seat, and arranged downstream of the valve seat atomizer disk. The atomizer disk has at least one inlet and a plurality of outlet ports, and thus a complete passage for fuel between the inlet and the outlet. A flow rate sensor is integrated upstream of a metering cross-section of the fuel passage in the atomizer disk with local electrically conductive regions provided on the atomizer disk. As the material silicon is used for the atomizer disk, wherein the desired structures are introduced in the atomizer disk by etching. Such a silicon atomizer disk has the disadvantage of a possibly insufficient breaking strength, which results from the brittleness of silicon. Especially with continuous loads z. B. at an injection valve (engine vibrations) there is a risk that the silicon plates break. The installation of silicon wafers on metallic components, such as injection valves, is complex because special stress-free clamping solutions must be found and the seal on the valve is problematic. Welding the atomizing disks made of silicon on the injection valve is z. B. not possible. In addition, there is the disadvantage of edge wear on the openings of the silicon wafers during frequent flowing through with a fluid.

Advantages of the invention

The atomizer disk according to the invention with the characterizing features of claim 1 has the advantage that it has a high functional integration. A particular advantage is that a flow rate sensor is integrated in the atomizer disk, with which a very high variability of the flow rate flowing through the atomizer disk can be set in the flow mode. In this way, the flow through the atomizer disk in flow operation is controllable and actively controlled at any time.

The measures listed in the dependent claims advantageous refinements and improvements of claim 1 atomizer disc are possible.

It is particularly advantageous to use composite ceramics produced as a material for the atomizer disk via pyrolysis of filled organosilicon polymers. These are very corrosion-resistant and wear-resistant, so that a long service life is guaranteed.

It is advantageous to arrange electrically conductive regions immediately upstream of the at least one outlet opening. In this case, a first electrically conductive region can be heated with electrical energy, and the temperature of a second electrically conductive region can be influenced by the fluid flow, and thus its electrical resistance can be changed. In this way, the flow rate upstream of the metering cross section of the fluid passage in the atomizer disk can be determined.

The fuel injection valve according to the invention with the characterizing features of claim 11 has the advantage that a continuous detection of the flow rate in the injection valve during operation of a motor vehicle is possible. In addition, the flow can be actively controlled at any time.

The flow accuracy of injectors need not, as previously customary, be ensured by accurate geometric dimensions in the metering range, especially in the outlet openings of the fuel injection valve in large quantities. Rather, the flow is controllable and adjustable by the inventive design of the atomizer disk in engine operation. In this way, the manufacturing costs for injectors can be reduced.

drawing

An embodiment of the invention is shown in simplified form in the drawing and explained in more detail in the following description. 1 shows a partially illustrated fuel injection valve with an atomizer disk in section, Figure 2 is a known from DE-OS 196 39 506 atomizer disk in a plan view to 2a to 2c, the individual functional levels of the atomizer disk according to Figure 2, Figure 3 is a section along the line III-III in Figure 2 and Figure 4 shows an embodiment of an atomizer disk according to the invention with integrated flow rate sensor in a contour design according to the atomizer disk shown in FIG.

Description of the embodiment

The electromagnetically actuated valve exemplified in FIG. 1 in the form of an injection valve for fuel injection systems of mixture-compression, spark-ignition internal combustion engines is particularly suitable as a high-pressure injection valve for injecting fuel directly into a combustion chamber of an internal combustion engine. For the use of the atomizer according to the invention an injection valve (for gasoline or diesel application, for direct or port injection) is only one important application. These atomizer discs can also be used in inkjet printers, nozzles for spraying liquids of any kind or inhalers.

The injection valve has a tubular valve seat carrier 1 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 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 z. B. a weld by means of a laser and aligned with the core 12.

To guide the valve closing body 7 during the axial movement is a guide opening 15 of a valve seat body 16 which is mounted in the downstream, the core 12 remote from the end of the valve seat support 1 in the concentric with the valve longitudinal axis 2 extending longitudinal opening 3 by welding. At its the valve closing body 7 facing away, lower end face 17 of the valve seat body 16 with a z. B. pot-shaped disk carrier 21 concentrically and firmly connected, which thus rests at least with an outer ring portion 22 directly to the valve seat body 16. The disk carrier 21 in this case has a similar shape to that already known cup-shaped spray perforated disks, wherein a central region of the disk carrier 21 is provided with a passage opening 20 without Zumessfunktion.

An atomizer disk 23 according to the invention is arranged upstream of the passage opening 20 such that it completely covers the passage opening 20. The disk carrier 21 is designed with a bottom part 24 and a retaining edge 26. The retaining edge 26 extends in the axial direction facing away from the valve seat body 16 and is bent conically outward to its end. The connection of valve seat body 16 and disc carrier 21st The disk carrier 21 is in the region of the retaining edge 26 further connected to the wall of the longitudinal opening 3 in the valve seat carrier 1, for example, by a circumferential and dense second weld 30.

The atomisable disk 23, which can be clamped between the disk carrier 21 and the valve seat body 16, is stepped, wherein above all a lower base region 32 has a larger diameter than the remaining atomizer disk 23. A disk region 33 having this smaller diameter protrudes into a downstream valve seat surface 29 cylindrical outlet opening 31 of the valve seat body 16 dimensionally accurate. The radially projecting and thus clampable base region 32 of the atomizer disk 23 bears against the lower end face 17 of the valve seat body 16.

While the disk area 33 z. B. two functional levels, namely a middle and an upper functional level, the atomizer disk 23 comprises, forms a lower functional level, the base area 32 alone. A functional level should have a largely constant opening contour over its axial extent.

The insertion depth of the consisting of valve seat body 16, cup-shaped disk carrier 21 and atomizer 23 valve seat portion 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 on the valve seat surface 29th of the valve seat body 16 is fixed. The other end position of the valve needle 5 is at energized solenoid 10, for example, by the system of the armature 11 to the core 12 set. The path between these two end positions of the valve needle 5 thus represents the stroke. The spherical valve closing body 7 interacts with the valve seat surface 29 of the valve seat body 16 which tapers in the shape of a truncated cone.

The insertion of the atomizer disk 23 with a disk carrier 21 and a clamp as attachment is only one possible variant of attaching the atomizer disk 23. Such a clamping as indirect attachment of the atomizer disk 23 on the valve seat body 16 has the advantage that temperature-induced deformations are avoided, possibly at Methods such as welding or soldering could occur in a direct attachment of the atomizer disk 23. However, the disk carrier 21 is by no means an exclusive condition for fixing the atomizing disk 23.

Figure 2 shows a known from DE-OS 196 39 506 atomizer disc in a plan view to illustrate and explain a possible shape of the atomizer disk according to the invention 23. The perforated disc 23 is designed as a flat, circular member having a plurality, for example, three axially successive functional levels , FIG. 3, which is a sectional view along a line III-III in FIG. 2, illustrates the structure of the perforated disk 23 with its three functional planes.

The upper functional level 37 has, for example, an inlet opening 40 with the largest possible circumference, which has a contour similar to a stylized bat (or a double H). The inlet opening 40 has a cross-section, which is a partially rounded rectangle with two opposite, rectangular constrictions 45 and three over the constrictions 45 overstanding inlet regions 46 can be described. With z. B. in each case the same distance from the central axis of the atomizer disk 23 and these are arranged symmetrically, for example, four rectangular outlet openings 42 are provided in the lower functional level 35.

With a projection of all functional planes 35, 36, 37 into one plane (FIG. 2), the outlet openings 42 lie largely in the constrictions 45 of the upper functional plane 37. The outlet openings 42 are at an offset from the inlet opening 40, ie. H. in the projection, the inlet opening 40 will not cover the outlet openings 42 at any point. In order to ensure a fluid flow from the inlet opening 40 to the outlet openings 42, a channel 41 (cavity) is formed in the middle functional plane 36. The contour of a rounded rectangle having channel 41 has a size such that it completely covers the inlet opening 40 in the projection. Since the channel 41 also covers the four outlet openings 42, they can be flown in from all sides.

In FIGS. 2 a, 2 b and 2 c, the functional planes 37, 36 and 35 are once again shown in isolation to precisely recognize the opening contour of each individual functional plane 37, 36 and 35. Each individual figure is ultimately a simplified sectional view horizontally along each functional plane 37, 36 and 35.

Due to the already mentioned offset of the outlet openings 42 with respect to the at least one inlet opening 40 results in an S-shaped flow pattern of the medium, for example of the fuel. Obtained by the radially extending channel 41 the medium is a radial velocity component. Due to the so-called S-impact within the atomizer disk 23 with several strong flow deflections, the flow is imparted with a strong, atomization-promoting turbulence. The velocity gradient across the flow is thus particularly pronounced. The increased shear stresses in the fluid resulting from the speed differences favor decay into fine droplets near the outlet ports 42.

In the course of the introduction of On Board Diagnostic (OBD) for internal combustion engines, the electronic monitoring of the functionality of exhaust-relevant components of a motor vehicle will be realized in the future. For fuel injection valves, such a quantity to be monitored represents the amount of fuel sprayed per opening stroke of the valve needle 5. According to the invention, therefore, a microstructured atomizing disk 23 is proposed which has a flow rate sensor with which an active control of the amount of fuel sprayed off is possible over the duration of the injection valve activation pulse.

FIG. 4 shows an exemplary embodiment of an atomizer disk 23 according to the invention with an integrated flow rate sensor, but otherwise with the exemplary contouring described above.

The atomizer disk 23 is made of ceramic material, for example. In the microstructuring of the atomizer disk 23, electrically conductive regions 50, 51 are selectively introduced by locally introduced conductivity in the material. In the exemplary embodiment shown in FIG. 4, the electrically conductive regions 50, 51 are in the lower functional plane 35, ie in the lower one Ceramic layer arranged. At the outer edge of the atomizer disk 23, the conductive regions 50, 51 terminate in contacting surfaces 50 ', 51'. The atomizer disk 23 is fastened to the fuel injection valve in such a way that these contacting surfaces 50 ', 51' come into contact with corresponding connection contacts, not shown, of the injection valve. The measuring and control signals, which are supplied to the flow rate sensor and removed, for example, can be processed in a control unit external to the injector.

In each case two electrically conductive strips 150, 151 run on the circumference of each individual outlet opening 42. These strips 150, 151 as part of the electrically conductive regions 50, 51 have a small relative distance from one another. As already described above, the outlet openings 42 are arranged so that they can be flown from all sides of the channel 41. The flow thus cuts the strips 150, 151 approximately at right angles before entering the outlet openings 42. The contact strip 50 'contacted strip 150 is heated with defined electrical energy. The fuel flow heated thereby downstream of this strip 150 subsequently comes in contact with the conductive strip 151 which is connected to the contacting surfaces 51 '. The heated fuel flow affects the temperature of the strip 151, thereby changing its electrical resistance. Depending on the flow rate or the flow rate of the strip 151 is heated to different degrees. Via the electrical resistance of the strip 151, the instantaneous flow rate can be determined by means of an evaluation circuit. During operation of a motor vehicle and its fuel injection valves, the flow rate of the injectors can thus be detected continuously. To this The flow can be controlled and actively regulated at any time.

The flow rate measurement principle on an atomizer disk is not limited to the atomizer disk 23 described in more detail with an offset of inlet port 40 and outlet ports 42, but quite different types of atomizer disks can be used for such purposes. Swirl disks. It is important, however, that the flow rate sensor is always arranged upstream of the metering cross section in its immediate vicinity.

As the material for the conductive regions 50, 51 and non-conductive regions, composite ceramics prepared by pyrolysis of filled organosilicon polymers are preferably used, as e.g. already known from EP 0 412 428 B1 or DE 195 38 695 A1. The electrical resistance of the composite ceramic can be adjusted via the type and quantity of filler. Microstructured sputter disks 23 can be produced by means of hot stamping and joining of incompletely cured moldings or by joining in the pyrolyzed state or by means of injection molding or transfer molding with lost molds. The electrically conductive regions 50, 51 including the strips 150, 151 are applied to the lower functional level 35, a ceramic base plate 32, 55 of the atomizing disk 23, either by doctoring or screen printing or by micro injection molding or transfer molding or two-layer composites of a non-conductive Substrate and a conductive thin layer produced by cold pressing and subsequent laser structuring.

In the case of micro injection molding or transfer molding with an insert, first the substrate, that is the Ceramic base plate 32, 55 injected and cured. Subsequently, the electrical regions 50, 51 are generated in a second injection process. In a following step, the upper functional planes 36, 37 of the atomizing disk 23 are molded onto the ceramic base plate 55 provided with the electrical regions 50, 51 by using lost molds.

When laser structuring two variants of the method are conceivable. On the one hand, structuring of the later strips 150, 151 can take place by laser ablation (evaporation of the material at locations where no conductive regions 50, 51 are to be formed). On the other hand, by partial pyrolysis at the locations of the later strips 150, 151 with subsequent etching of the remaining Leitverbundcompounds structuring of the strips 150, 151 done. The parts thus produced are pyrolyzed as described in EP 0 412 428 B1. It should be noted that the nonconductive (base plate 32, 55) and conductive (strip 150, 151, contacting surfaces 50 ', 51') composite ceramic with respect to pyrolysis and thermal expansion coefficients are matched to prevent cracking during the pyrolysis process.

Claims (13)

1. Atomizing disc (23) with at least one inlet (40) and at least one outlet (42) and with a complete passage for a fluid between the inlet (40) and the outlet (42), a flow rate sensor (50, 51, 50', 51', 150, 151) being integrated in the atomizing disc (23) upstream of a cross section to be measured of the fluid passage, which disc has local electrically conducting regions (50, 51), characterized in that the material for the atomizing disc (23) is a composite ceramic produced by pyrolysis of filled organosilicon polymers.
2. Atomizing disc according to Claim 1, characterized in that the electrically conducting regions (50, 51) are arranged directly upstream of the at least one outlet opening (42).
3. Atomizing disc according to Claim 2, characterized in that two electrically conductive strips (150, 151) respectively run around the circumference of each outlet opening (42).
4. Atomizing disc according to Claim 3, characterized in that the strips (150, 151) are at a small distance from one another.
5. Atomizing disc according to one of Claims 2 to 4, characterized in that a first electrically conductive region (50, 150) can be heated with electrical energy.
6. Atomizing disc according to Claim 5, characterized in that the temperature of a second electrically conductive region (51, 151) can be influenced by the fluid flow, and consequently its electrical resistance can be varied.
7. Atomizing disc according to Claim 6, characterized in that the flow rate upstream of a cross section to be measured of the fluid passage in the atomizing disc (23) can be determined by means of the electrical resistance of the second electrical region (51, 151).
8. Atomizing disc according to one of Claims 1 to 7, characterized in that the electrically conducting regions (50, 51, 150, 151) end at the outer edge of the atomizing disc (23) in contacting areas (50', 51'), which can be connected to terminal contacts leading to an evaluation circuit.
9. Fuel injection valve for fuel injection systems of internal combustion engines, with an actuator (10, 11, 12), with a movable valve part (5), which interacts with a fixed valve seat (29) for opening and closing the valve, and with an atomizing disc (23), which is arranged downstream of the valve seat (29) and is formed with at least one inlet (40) and at least one outlet (42) and with a complete passage for fuel between the inlet (40) and the outlet (42), a flow rate sensor (50, 51, 50', 51', 150, 151) being integrated in the atomizing disc (23) upstream of a cross section to be measured of the fuel passage, which disc has local electrically conducting regions (50, 51), characterized in that the material for the atomizing disc (23) is a composite ceramic produced by pyrolysis of filled organosilicon polymers.
10. Fuel injection valve according to Claim 9, characterized in that the electrically conducting regions (50, 51) are arranged directly upstream of the at least one outlet opening (42).
11. Fuel injection valve according to Claim 10, characterized in that a first electrically conductive region (50, 150) can be heated with electrical energy and in that the temperature of a second electrically conductive region (51, 151) can be influenced by the fluid flow, and consequently its electrical resistance can be varied, whereby the flow rate upstream of a cross section to be measured of the fuel passage in the atomizing disc (23) can be determined.
12. Fuel injection valve according to one of Claims 9 to 11, characterized in that the electrically conducting regions (50, 51, 150, 151) end at the outer edge of the atomizing disc (23) in contacting areas (50', 51'), which can be connected to terminal contacts leading to an evaluation circuit.
13. Fuel injection valve according to Claim 12, characterized in that the atomizing disc (23) can be electrically connected to a control device via the contacting areas (50', 51').

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