DE4421881A1 - Valve needle - Google Patents

Abstract

In prior art fuel-injection valves, fuel filters are inserted into the fuel-inlet pipe where they are secured in place. These fuel filters ensure that certain constituants which could, by virtue of their particle size, block or damage the valve are filtered out of the fuel fed to the valve. Foreign bodies inside the valve which originate from components inserted into the valve, from wear of stop surfaces or from production-related burring are not filtered out however, resulting in the danger of blockages or leakage at the valve seat. The valve needle (18) proposed, for a fuel-injection valve for instance, has a filter element (20) integrated in or on it. The function of this filter element (20) is to keep any particles or other impurities inside the valve upstream of the valve seat (30) away from the valve seat (30) and hence avoid blockages or leakage at the valve seat (30). The valve needle proposed is particularly suitable for use in injection valves in fuel-injection systems for mixture-compression external-ignition-combustion engines.

Description

State of the art

The invention is based on a valve needle according to the Gat main claim. It's already out of the DE-OS 40 03 228 one from an anchor, a valve needle cut and a valve closing body formed valve needle as an actuator for opening and closing a burner known fuel injection valve in which u. a. a focal Fabric filter at the inlet end of the fuel injection valve is pressed into the fuel inlet connector. Of the Fuel filter ensures that such are filtered out Fuel components that due to their size in one spray valve cause blockages or damage could. This fuel filter is on the circumference, for example provided with a brass ring that matches the wall of the Fuel inlet connector the pairing when the Fuel filter forms. As a disadvantage of this method there is a possible occurrence of abrasion and late nen, which during the pressing in due to the interference fit Fuel filter and fuel inlet connection, the same time serves as the core, can be replaced and then used for ver  cause dirt in the injector. Impurities in the The inside of the injection valve can also be inserted an adjusting sleeve in the flow hole of the core Wear on the contact surfaces of the core and anchor for example, due to production-related burrs on various Components of the injection valve occur or arise. This built-in or shaken off Dirt inside the injector can get through the Fuel filter at the inlet end of the fuel spray valve can not be prevented. As a result, can it in the most extreme case to constipation respectively Leaks at the valve seat come, so that the injection til is no longer fully functional.

Advantages of the invention

The valve needle according to the invention with the characteristic In contrast, features of the main claim have the advantage that built-in relationship inside the injector wise dirt is kept away from the valve seat, so that no impact of these particles on the Tightness of the injection valve in the area of the valve seat occur and blockages on the valve seat are excluded are. This is advantageously achieved in that a fil integrated in or on the valve needle terelement is provided in the injection valve, which all Par particles and contaminants upstream of the valve seat in the Inside of the injector from the valve seat due to deposits on the filter element and thus the mentioned stoppage prevent valve seat.

By the measures listed in the subclaims advantageous developments and improvements in Main claim specified valve needle possible.  

drawing

Embodiments of the invention are in the drawing shown in simplified form and in the following description exercise explained in more detail. Show it

Fig. 1 is a Brennstoffein injection valve with an inventive valve needle, Fig. 2 shows a first embodiment of this valve needle, Fig. 3 shows a second embodiment of a valve needle, Fig. 4 shows a section along the line IV-IV in Fig. 3, Fig. 5 shows a third embodiment of a valve needle, Fig. 6 shows a section along the line VI-VI in Fig. 5, Fig. 7 is a plan view of a valve needle according to a fourth embodiment, Fig. 8 a section along the line VIII-VIII in Fig. 7, Fig . 9 is a section along the line IX-IX in Fig. 8, Fig. 10 shows a section along the line XX in Fig. 8 and Fig. 11 shows a fifth example of execution of a valve needle.

Description of the embodiments

The electromagnetic table-actuated valve shown in FIG. 1, for example, in the form of an injection valve for fuel injection systems of mixture-compressing, spark-ignited internal combustion engines has one surrounded by a magnet coil 1 , the tubular core 2 serving as fuel inlet connector, which has a constant outer diameter, for example, over its entire length . A bobbin 3 stepped in the radial direction receives a winding of the magnet coil 1 and, in conjunction with the core 2, enables a compact structure of the injection valve in the region of the magnet coil 1 .

With a lower core end 9 of the core 2 , a tubular metal intermediate part 12 is tightly connected concentrically to a longitudinal valve axis 10, for example by welding, and thereby partially surrounds the core end 9 axially. The stepped coil body 3 overlaps the core 2 and the intermediate part 12 at least partially axially. Downstream of the bobbin 3 and the intermediate part 12 , a tubular valve seat support 16 extends, for example, is firmly connected to the inter mediate part 12 . In the valve seat carrier 16 ver runs a longitudinal bore 17 which is concentric with the valve longitudinal axis 10 . In the longitudinal bore 17 , a valve needle 18 according to the invention is arranged with, for example, a tubular valve needle section 19 , which is designed together with a filter element 20, for example in the form of a sieve stocking. At the downstream end 23 of the valve needle section 19 , a spherical Ven valve closing body 24 is provided, on the circumference of which, for example, five flats 25 are provided for the fuel to flow past and which is connected, for example, by welding to the tubular valve needle section 19 .

The injection valve is actuated in a known manner, for example electromagnetically. The electromagnetic circuit with the magnet coil 1 , the core 2 and an armature 27 is used for the axial movement of the valve needle 18 and thus for opening against the spring force of a return spring 26 or closing the injection valve. The armature 27 is connected to the end of the valve needle section 19 facing away from the valve closing body 24 by a weld seam and is aligned with the core 2 . The armature 27 and the valve closing body 24 connecting the valve needle section 19 forms, together with these two at the upstream and at the downstream end of the valve needle section 19 is arrange th components or portions of the valve needle 18th

In the downstream, the core 2 facing end of the valve seat carrier 16 is a cylindrical valve seat body 29 in the longitudinal bore 17 , which has a fixed Ven valve seat 30 , tightly mounted by welding.

To guide the valve closing body 24 during the Axialbe movement of the valve needle 18 with the armature 27 along the Ven tillängsachse 10 is a guide opening 32 of the valve seat body 29th The spherical valve closing body 24 cooperates with the valve seat 30 of the valve seat body 29 which tapers in the direction of the truncated cone. On its front side facing away from the valve closing body 24 , the valve seat body 29 is concentric and firm with a cup-shaped spray orifice plate 34 , for example, by a circumferential, dense weld seam, for example formed by a laser. At least one, for example four, spray openings 39 formed by erosion or stamping are provided in the, for example, pot-shaped spray perforated disk 34 . A protective cap 43 is arranged on the periphery of the valve seat carrier 16 at its downstream end facing away from the core 2 and is connected to the valve seat carrier 16 , for example, by means of a catch.

The insertion depth of the valve seat body 29 with the spray orifice plate 34 determines the preset of the stroke of the Ven tilnadel 18th The one end position of the valve needle 18 when the magnet coil 1 is not energized is determined by the contact of the valve closing body 24 on the valve seat 30 of the valve seat body 29 , while the other end position of the valve needle 18 results when the magnet coil 1 is excited by the contact of the armature 27 at the core end 9 .

The magnet coil 1 is surrounded by at least one, for example designed as a bracket and serving as a ferromagnetic guide element 45 which at least partially surrounds the magnet coil 1 in the circumferential direction and rests with its one end on the core 2 and its other end on the Ven seat holder 16 and can be connected to this for example by welding, soldering or gluing.

An inserted into a run concentrically to the valve longitudinal axis 10 de flow bore 46 of the core 2 setting sleeve 48 serves to adjust the preload on the bearing against the adjusting sleeve 48 return spring 26, which in turn delabschnitt with its opposite side on the Ventilna supported 19th

The injection valve is largely enclosed with a plastic injection 50 , which extends from the core 2 in the axial direction via the magnet coil 1 and the at least one guide element 45 to the valve seat support 16 , the at least one guide element 45 being completely covered axially and in the circumferential direction. This plastic encapsulation 50 includes, for example, an injection molded electrical connector 52 .

In addition to the filter element 20 provided on the valve needle 18 according to the invention, the injection valve can have a fuel filter 55 . The fuel filter 55 then protrudes into the flow bore 46 of the core 2 at its inlet end 56 facing away from the spray orifice plate 34 . The fuel entering the fuel injection valve flows through the fuel filter 55 in a known manner and exits the fuel filter 55 in the radial direction. The fuel filter 55 ensures that such particles carried in the fuel are filtered out, which, because of their size or chemical composition in the injection valve, could cause blockages or damage. For example, the fuel filter 55 can be installed by pushing it into the stepped flow bore 46 of the core 2 , and in the assembled state, for example, with a retaining ring. 58 abuts with a slight radial pressure on the wall of the flow bore 46 . The filter web of the fuel filter 55 is fastened in a cup-shaped carrier part 60 made of plastic with, for example, three axial webs 61 .

In addition to the fuel filter 55 at the inlet end 56 of the core 2 or instead, the filter element 20 is provided on the valve needle 18 designed according to the invention. In the assembled state of the injection valve, the filter element 20 is integrated in or on the valve needle 18 . From a manufacturing point of view, however, it makes sense to manufacture the filter element 20 separately from the individual components of the valve needle 18 . The pushing on, inserting or other options for attaching the filter element 20 in or on the valve needle 18 are explained in more detail below. The filter element 20 arranged in or on the valve needle 18 has the function of keeping all particles and impurities upstream of the valve seat 30 in the interior of the injection valve from the valve seat 30 and thus preventing blockages or leaks at the valve seat 30 . Contamination inside the injector can occur, for example, when inserting the adjusting sleeve 48 , when the fuel filter 55 is pressed in , due to wear on the abutment surfaces of the core 2 and armature 27 or through production-related burrs on various components of the injector.

In Fig. 1, a very simple combination of the Fil terelements 20 with the valve needle 18 is shown. The Fil terelement 20, for example, from a conventional polyamide fabric as a screen fabric 62 is drawn in the form of a sieve stocking without a plastic reinforcement over the valve needle portion 19 and completely surrounds it radially over the entire axial extension length. The sieve stocking is welded, for example, to the valve needle section 19 with an axially running seam 63 and thus sits tightly on the valve needle section 19 . Figs. 2 to 11 show various embodiments of integrated in or on the valve needle 18 Filter elements 20. In these figures, the representation of the entire injection valve is dispensed with, since the fuel injection valve shown in FIG. 1 is intended only as an example for possible uses of filter elements 20 and therefore other series of valves, especially injection valves, can also be equipped with the valve needles 18 according to the invention . The compared to the Ausfüh shown in FIG. 1 example of the valve needle 18 constant or equivalent parts are also identified in FIGS . 2 to 11 by the same reference numerals.

A valve needle 18 with the filter element 20 designed as a filter stocking according to the exemplary embodiment shown in FIG. 1 is shown again in FIG. 2. Without a plastic reinforcement in the form of a carrier body, the filter element 20 is pulled over the valve needle section 19 and surrounds it completely radially. In addition to the welding already mentioned (seam 63 ), slipping of the filter element 20 is also ruled out in that the armature 27 as part of the valve needle portion 19 for example by welding firmly engages the Siebge webe 62 and cut between itself and the Ventilnadelab 19 clamps.

A second embodiment of a valve needle 18 with the filter element 20 attached to the outer circumference of the valve needle section 19 is shown in FIGS . 3 and 4. The hülsenför shaped filter element 20 , which is shown in section in FIG. 3, is now similar to the fuel filter 55 ausgebil det , ie consisting of a carrier body 64 made of plastic, for example, and the actual screen fabric 62 , for example a polyamide fabric. The screen fabric 62 is molded on, for example, during the manufacture of the carrier body 64 . The carrier body 64 is encircled by a ring section 67 , which extends away from the valve closing body 24 , and by, for example, three axial webs 65 which run in the axial direction and are offset by 120 ° on the circumference of the filter element 20 and which minimally cover the sieve web 62 , educated. The axial webs 65 thus extend from the ring section 67 to the valve closing body 24 . Fig. 4 as a sectional view of a section along the line IV-IV in Fig. 3 again illustrates the arrangement of the Axialste ge 65 , which have only a small width and thus cover the fuel outlet openings in the valve needle section 19 to a small extent only in an unfavorable position. The ring portion 67 is formed so that it can grip an existing at the downstream end of the armature 27 collar 70 and thus there is a latching between the support body 64 and armature 27 , whereby slipping of the Fil terelements 20 is excluded. In this exemplary embodiment, the filter element 20 is therefore completely outside of the actual valve needle 18 .

In contrast, the filter element 20 is in the following embodiment, which is shown in FIGS . 5 and 6, inserted into the tubular valve needle portion 19 ben. The filter element 20 has a largely similar Liche shape which is shown in FIGS . 3 and 4 Fil terelement 20th It also consists of a carrier body 64 made of plastic and the screen fabric 62 . In order to obtain sufficient stability of the filter element 20, the carrier body 64 has a valve closing body 24 facing the bottom 72, a circumferential, the Ven tilschließkörper 24 facing away from ring portion 67 and two or three between ring portion 67 and bottom 72 axially ver current and 180 ° or axial webs 65 which are offset by 120 ° on the circumference of the filter element 20 . The screen fabric 62 is, for example, in turn injected during the manufacture of the carrier body 64 . While the bottom 72 completely closes the inner diameter of the valve needle section 19 between the fuel outlet openings and the valve closing body 24 and can thus serve to deposit the particles and contaminants, the ring section 67 is an open cross section, so that the fuel unhindered into the valve needle section 19 can flow. The filter element 20 is thus cup-shaped. The ring portion 67 has, for example, such an outer diameter that there is an interference fit in the valve needle portion 19 , so that a very simple type of fastening is guaranteed, the force of a human finger being fully sufficient to insert the filter element 20 . Fig. 6, which shows a section along the line VI-VI in Fig. 5, illustrates the arrangement of, for example, three axial webs in the interior of the Ventilna delababschnitt 19th

In Fig. 8, an actuating part consisting of the valve needle portion 19 and the armature 27 , which is made in one piece by the so-called metal injection molding process (MIM) ago, is shown in section. The method already known from DE-PS 42 30 376 includes the production of molded parts from a metal powder with a binder, for example a plastic binder, for example on conventional plastic injection molding machines and the subsequent removal of the binder and sintering of the remaining metal powder structure. The valve closing body 24 is then for example by means of a welded connection at the downstream end of the actuation supply part with the valve needle portion 19 firmly and tightly connected. A valve needle 18 , in which at least the actuating part of valve section 19 and armature 27 is formed in one piece as a MIM part and the valve needle section 19 is a solid part, has already been proposed in German patent application DE-P 44 15 850.5.

FIG. 7 shows a top view of the valve needle 18 or the armature 27 from an upstream end face 74 facing the core 2 . In this plan view, can be seen clearly that an axially opposite the end face 74 deeper and has a smaller diameter than the end face 74 having Direction retaining shoulder 75 26 axially by, for example three or four, 10 extending axial grooves for supporting the return spring that is, in the direction of the longitudinal valve axis 76 is interrupted. The axial grooves 76 extend over the entire remaining length of the armature 27 and serve to allow the fuel coming from the flow bore 46 of the core 2 to flow unhindered in the direction of the valve seat 30 .

Fig. 8 is a representation of a section along the line VIII-VIII in Fig. 7, the section being made so that it runs through the solid material from the Halteab set 30 starting in the axial direction of the armature 27 and through one Axial groove 76 in armature 27 . The Ventilna delabschnitt 19 partially protrudes into the armature 27 , that is, an upstream, the holding shoulder 30 facing end face 77 of the valve needle portion 19 is further upstream than a result 78 on the outer contour of the actuating part of the armature 27 to valve needle portion 19th , where the axial grooves 76 end. The axial grooves 76 , however, in their lower section, namely precisely from the end face 77 of the valve needle section 19, no longer represent nu, but rather, due to the complete closure of the material, aligned, axial flow channels 80 . The fuel emerges from the flow channels 80 in the area of the heel 78 at least partially as a wall film of the valve needle section 19 , since the internal limitation of each flow channel 80 is given by the valve needle section 19 . Immediately downstream of the shoulder 78 , the fuel can enter a filter element 20 surrounding the valve needle section 19 .

The sleeve-shaped filter element 20 is fastened, for example, similarly to the embodiment shown in FIGS . 3 and 4, for example, by latching on the valve needle section 19 . For this purpose, the valve needle section 19 as a section of the actuating part produced by means of the MIM method has, for example, four latching lugs 82 on its circumference axially close to the shoulder 78 , which are each offset on the valve needle section 19 by 90 °. This locking lugs 82 can now encompass a carrier body 64 made of plastic of the filter element 20 , with which a secure fixation of the filter element 20 on the valve needle 18 is guaranteed. Flow spaces 83 remain in the circumferential direction between the latching lugs 82 for the fuel to be flowed via the flow channels 80 , since the carrier body 64 with its upper ring section 85 has a larger inner diameter than the diameter of the valve needle section 19 between the latching lugs 82 . In order to ensure sufficient stability, in addition to the upper ring section 85 , a lower ring section 86 also belongs to the carrier body 64 , which forms the downstream end of the filter element 20 . The screen fabric 62 , over which cut between the two Ringab 85 and 86 of the fuel flows radially outwards, has also been injected, for example, in the manufacture of the carrier body 64 . The two ring sections 85 and 86 can be connected to one another by axial webs or can also be separate from one another if only the sieve fabric 62 between the two ring sections 85 and 86 is to be present.

FIGS. 9 and 10 are representations of sections ent long the lines IX-IX, respectively XX in Fig. 8 by the upper ring portion 85 of the support body 64 of the filter element 20. The formation of the locking lugs 82 , which extend at 90 ° from the circumference of the valve needle section 19 radially outward and thus offer the possibility of locking the carrier body 64 , is particularly clear. The inner opening of the ring portion 85 of the carrier body 64 is not circular, but with different areas of larger and smaller opening width. To accommodate the four locking lugs 82 , four recesses 88 are provided in the ring section 85 , for example, in which the locking lugs 82 engage. The flow spaces 83 formed between two locking lugs 82 have their greatest width exactly in the middle between two locking lugs 82 , since the valve needle section 19 has a circular cross section and the inner opening of the ring section 85 has a largely square cross section. A circle arranged centrally in a square always has the greatest distance from the corner points of the square, which are therefore exactly in the middle between two locking lugs 82 . The fuel comes from the axial grooves 76 coming through the flow channels 80 in the armature 27 directly into the flow spaces 83 and then exits radially through the screen fabric 62 from the filter element 20 in the direction of the valve seat 30 . Particles entrained in the fuel can be deposited in a wedge opening 89 of the lower ring section 86 , which is slightly wedge-shaped toward the valve needle 18 .

In the case of a very short valve needle 18 , which was already proposed in German patent application DE-P 43 10 819.9 and is shown in FIG. 11, it is advisable to use a filter element 20 in the form of a plate spring. The actuating part consisting of armature 27 and valve needle section 19 is, for example, in one piece and has at least one flow channel 80 running in armature 27 , which ends at paragraph 78 of the armature 27 on the outer contour of the actuating part, ending with armature 27 to valve needle section 19 , so that the fuel is immediate can get to the valve seat 30 . The filter element 20 is therefore located between the end of the flow channel 80 at the shoulder 78 and the valve seat 30 . With the very small installation space that results from the short valve needle 18 , it is only possible to use a filter element 20 with small dimensions. The filter element 20 therefore has only two, a very small cross-section possessing, circumferential, made of plastic or metal retaining rings 90 , 91 , which have a different diameter and clamp the screen fabric 62 between. The mesh fabric 62 extends downstream Windwärts frustoconically tapered, since the valve-closure member 24 facing the retaining ring 91 has a smaller diameter than the valve closing body 24 abgewan dte retaining ring 90th The retaining rings 90 and 91 of the filter element 20 are accommodated in ring grooves 92 provided on the shoulder 78 of the armature 27 and on the valve needle section 19 . A sufficiently secure fit is guaranteed by clipping or pressing the retaining rings 90 into the ring receiving grooves 92 (press fit).

The described and also other similar forms of Fil terelements 20 can come to use on a wide variety of valve needles 18 of valves, especially of injection valves, also on valve needles not explained in more detail here.

Claims (10)

1. Valve needle, in particular for electromagnetically actuated fuel injection valves for fuel injection systems of internal combustion engines, with a valve needle section and a valve closing body, characterized in that the valve needle ( 18 ) has a filter element ( 20 ). 2. Valve needle according to claim 1, characterized in that the filter element ( 20 ) in the form of a sieve stocking consists only of a sieve fabric ( 62 ). 3. Valve needle according to claim 1, characterized in that the filter element ( 20 ) from a carrier body ( 64 ) and a screen fabric ( 62 ) is formed. 4. Valve needle according to claim 2 or 3, characterized in that the screen fabric ( 62 ) of the filter element ( 20 ) is a polyamide fabric. 5. Valve needle according to claim 1, characterized in that the filter element ( 20 ) surrounds the valve needle portion ( 19 ) of the valve needle ( 18 ) externally. 6. Valve needle according to claim 1, characterized in that the filter element ( 20 ) in the interior of the tubular valve th portion ( 19 ) of the valve needle ( 18 ) is angeord net. 7. Valve needle according to claim 1, characterized in that the filter element ( 20 ) by a snap connection ( 67 , 70 ; 82 , 85 ) on the valve needle ( 18 ) is fixed. 8. Valve needle according to claim 1, characterized in that the filter element ( 20 ) has a sleeve-shaped, cup-shaped or frustoconical shape. 9. Valve needle according to claim 1, characterized in that the valve needle section ( 19 ) on its side facing away from the valve closing body ( 24 ) is connected to an armature ( 27 ) and the screen fabric ( 62 ) is at least axially between the valve closing body ( 24 ) and the anchor ( 27 ) extends. 10. Valve needle according to claim 1, characterized in that the valve needle section ( 19 ) on its side facing away from the valve closing body ( 24 ) is connected to an armature ( 27 ) and the filter element ( 20 ) by a latching ( 67 , 70 ) on the Anchor ( 27 ) is attached.