EP0865574B1 - Fuel injection valve and method of producing the same - Google Patents

Description

State of the art

The invention is based on a fuel injector according to the preamble of claim 1 and a method for Manufacture of a fuel injector according to the Genus of claim 10.

From US Pat. No. 4,946,107 there is already an electromagnetic one Actuable fuel injector known that under other a non-magnetic sleeve as a connecting part has between a core and a valve seat body. With the two axial ends of the sleeve are fixed to the core and connected to the valve seat body. The sleeve runs over their entire axial length with a constant Outside diameter and a constant inside diameter. The The core and the valve seat body are with one Outside diameter formed that they in the sleeve to the extend both ends so that the sleeve the two Components of the core and valve seat body projecting into them Areas completely surrounded. Moved inside the sleeve a valve needle with an armature extends in the axial direction, which is passed through the sleeve. The firm connections the sleeve with the core and the valve seat body are z. B. achieved by welding. The core and the non-magnetic Sleeve together delimit an inner valve part to the outside, which is manufactured and adjusted separately and later the Interior of the fuel injector forms. This inner The valve part is ultimately one of several others Individual components in the assembled state of the Injector surrounded, at least one cup-shaped Housing part, a magnetic coil with. Bobbin, a cup-shaped coil housing and a plug part required become. The arrangement and design of the many, the Individual parts surrounding the valve part are relative consuming. It also needs a variety of connections between the outer individual parts and the inner valve part getting produced.

From DE-OS 43 10 819 is also a Fuel injector known which one non-magnetic thin-walled sleeve as valve seat support having. The entire, pre-set Fuel injector, including the sleeve largely enclosed with a plastic encapsulation that starting from the core in the axial direction over the Magnet coil until the downstream termination of the Injector extends. The deep-drawn sleeve has only a very small wall thickness (<0.3 mm) to the magnetic flux with the lowest possible losses over the to guide non-magnetic sleeve. To overmold the Injector valves with plastic are high encapsulation pressures (up to 350 bar) required to deform the sleeve can lead, whereby assembly and functional problems of the Injector can occur.

From the documents DE 44 21 881 A1 and DE 44 42 350 A1 already known fuel injectors, at their downstream valve ends from protective or attachment caps Plastic are attached. The protective or end caps are by means of a detent with a valve seat support connected. Such a protective cap can have several protective tines have, distributed over the circumference axially away from the valve protrude. Is, for example, an atomizing sieve in the Protective cap integrated, so can protect against mechanical influences the protective tines of the protective cap further downstream than the deepest part of the Atomizing sieve protrude. The protective or end caps fulfill a purely protective function of the downstream Fuel injector components. The attachment of the Protective or attachment caps are only made on downstream end of the valve.

Advantages of the invention

The fuel injector according to the invention with the characterizing features of claim 1 has the advantage that it can be assembled inexpensively in a simple manner is. According to the invention, this simplified assembly of the Fuel injector achieved in that two Main parts of the injection valve, a valve part and a Plastic part, made separately and can be set. The inner valve part is in advantageously with a non-magnetic, thin-walled sleeve, whose Use a cost saving compared to known valves brings, because material savings are possible and on the Joining to connect individual components is partially omitted can be. It is also advantageous that the outer Plastic part has an inner through opening, in which the valve part can be used very easily and by a simple, yet secure snap connection can be attached is.

This separation into two main components results in the special advantage that all negative influences when Manufacture of plastic extrusion (large Overmolding pressures, heat development) of which the important ones Components of the valve part that perform valve functions be kept away. A deformation of the thin-walled sleeve of the valve part by the encapsulation pressure completely excluded. The relatively dirty one Overmolding process can advantageously outside the assembly line of the valve part (clean room).

By the measures listed in the subclaims advantageous further developments and improvements of the Claim 1 specified fuel injector possible.

The production of the Snap connection by engaging, snapping or Clip a locking element on the plastic part into a groove on the outer circumference of the valve part. The locking elements can to have the most varied contours, e.g. B. angular or be rounded.

drawing

An embodiment of the invention is in the drawing shown in simplified form and in the following Description explained in more detail. 1 shows it fuel injector according to the invention, Figure 2 a outer tubular plastic part and Figure 3 an inner Valve part, the parts of Figures 2 and 3 assembled and connected to one another according to a fuel injector Figure 1 result.

Description of the embodiment

The example shown in Figure 1 Electromagnetically actuated valve in the form of a Injector for fuel injection systems from mixture-compressing, spark-ignition internal combustion engines has one surrounded by a magnetic coil 1, as Fuel inlet connector serving tubular core 2. A in the radial direction stepped bobbin 3 takes one Winding the solenoid 1 on and allows in Connection with the core 2 a particularly compact structure of the injection valve in the area of the solenoid coil 1. The Magnetic coil 1 is at least with its coil body 3 one, for example designed as a bracket and as Surrounding ferromagnetic element serving guide element 5, that the magnetic coil 1 at least in the circumferential direction partially surrounds and with its upper end 6 on the core 2 is applied. The at least one guide element 5 is of this type graduated that an axially parallel Main section 7 and the upper end 6 by a radial extending connecting section 8 are connected. The Connection section 8 provides a lid of the Magnetic coil area upwards. To close the magnetic circuit is the guide element 5 at its lower Late 9 z. B. with a cross-section L-shaped guide ring 9th for example by one or more welding spots connected after the limitation of the magnetic coil area below or in the downstream direction. The the magnetic flux conductive parts guide element 5 and Guide ring 10 enclose the bobbin 3 wound magnetic coil 1 at least partially pot-shaped.

With a lower core end 15 of the core 2, which is somewhat has a smaller outer diameter than the inlet side serving as the fuel inlet upper end of the core 2 concentric to a valve longitudinal axis 16 tightly as a Connecting part-serving tubular and thin-walled sleeve 18, for example by welding, connected and surrounding the core end 15 with an upper sleeve section 19 partially axial. The bobbin 3 overlaps the Sleeve section 19 of the sleeve 18 at least partially axially. The coil body 3 has namely over its entire axial Extension a larger inner diameter than that Diameter of the sleeve 18 in its upper sleeve section 19th The tubular sleeve 18 from, for example non-magnetic steel extends downstream with a lower sleeve section 20 to the downstream Completion of the fuel injector, the lower Sleeve section 20 a slightly smaller diameter has the diameter of the upper sleeve section 19. The diameter reduction in the form of a small paragraph 23 is located in the area of the upper end of the Leitring 10, since the Leitring 10 a minimally smaller Has inner diameter than the inner diameter of the Bobbin 3. This configuration contributes to the safe Assembly of the injector, which will be detailed later is described.

The sleeve 18 is thus over its entire axial length tubular. The sleeve 18 forms over her total axial extent with a through opening 21 apart from paragraph 23 largely constant diameter, which runs concentrically to the valve longitudinal axis 16. With their sleeve section downstream of paragraph 23 surrounds the sleeve 18 an anchor 24 and further downstream a valve seat body 25. One with the valve seat body 25 at its downstream end face firmly connected z. B. Cup-shaped spray disk 26 is from the sleeve 18 in Circumferential direction also enclosed, the fixed Connection of valve seat body 25 and spray orifice plate 26 z. B. realized by a circumferential dense weld is. The sleeve 18 is thus not only a connecting part, but it also fulfills holding or carrier functions, especially for the valve seat body 25, so that the sleeve 18 really is valve seat support. In the Through opening 21 is a z. B. tubular valve needle 28 arranged at its downstream, the Spray hole 26 facing end 29 with a z. B. spherical valve closing body 30, on the circumference for example five flats 31 to flow past the fuel to be sprayed are provided, for example is connected by welding.

The injection valve is actuated in a known manner Way electromagnetic. For the axial movement of the Valve needle 28 and thus to open against the spring force a return spring 33 or closing the injection valve serves the electromagnetic circuit with the magnetic coil 1, the core 2, the at least one guide element 5, the guide ring 10 and the anchor 24. The anchor 24 is with the Valve closing body 30 facing away from the end of the valve needle 28 z. B. connected by a weld and on the core 2nd aligned. For guiding the valve closing body 30 during the axial movement of the valve needle 28 with the armature 24 along the valve longitudinal axis 16 is used Guide opening 34 of the valve seat body 25. In addition the armature 24 during the axial movement in the sleeve 18th guided.

The spherical valve closing body 30 acts with one tapered in the direction of flow Valve seat surface 35 of the valve seat body 25 together, the in the axial direction downstream of the guide opening 34 is trained. The cup-shaped spray hole disk 26 has in addition to a bottom part 41 on which the Valve seat body 25 is attached and in the at least one, for example four, by eroding or stamping molded spray openings 42 run one circumferential downstream holding edge 43. The Holding edge 43 is bent conically downstream, so that this is determined by the through opening 21 inner wall of the sleeve 18 abuts, with a radial Pressure is present. At its downstream end is the Holding edge 43 of the spray plate 26 with the wall of the Sleeve 18, for example, by a circumferential and dense z. B. connected by a laser generated weld. An immediate flow of the fuel into a Intake pipe of the internal combustion engine outside the Spray openings 42 is through the welds on the Spray plate 26 avoided.

The insertion depth of the valve seat body 25 with the Spray plate 26 in the sleeve 18 is among other things decisive for the stroke of the valve needle 28. The an end position of the valve needle 28 when not excited Solenoid coil 1 through the contact of the valve closing body 30 on the valve seat surface 35 of the valve seat body 25 fixed while the other end position of the Valve needle 28 with solenoid 1 excited by the system of the armature 24 at the core end 15 results. In addition, the Stroke adjustment by moving the axially with little Oversized core 2 in the upper sleeve section 19 of the sleeve 18. The core 2 is in the corresponding desired position subsequently firmly with the sleeve 18th connected, wherein a laser weld on the circumference of the sleeve 18th makes sense. The interference of the press fit can also be chosen large enough so that the occurring Forces can be absorbed and complete Tightness is guaranteed, resulting in a weld can be dispensed with.

In a concentric to the longitudinal axis 16 of the valve stepped flow bore 38 of the core 2, that of the feed the fuel towards the valve seat, especially the Serves valve seat surface 35 is an adjusting sleeve 39th inserted. The adjusting sleeve 39 is used to adjust the Spring preload of the adjoining the adjusting sleeve 39 Return spring 33, which in turn with her opposite side is supported on the valve needle 28. On Fuel filter 40 projects into the flow bore 38 of the core 2 at its inlet end and ensures that Filtering out such fuel components, the due to their size in the injector clogging or Could cause damage.

The injector is completely set and assembled largely surrounded by a plastic jacket 50, which itself starting from the core 2 in the axial direction over the Solenoid coil 1 until the sleeve 18 is terminated downstream extends, to this plastic jacket 50 co-molded electrical connector 51 belongs. About the electrical connector 51 takes place electrical contacting of the magnetic coil 1 and thus its Excitement. As shown in Figure 2, it is the Plastic jacket 50 around a tubular plastic part that significantly better known from plastic extrusion Fuel injectors differs.

In the figure 2 is an outer tubular plastic part 60 with the solenoid assembly shown mainly from the plastic jacket 50 with the Connector 51 is formed. This plastic part 60 consists specifically of the magnetic coil 1, which the windings the magnetic coil 1 carrying coil body 3 made of plastic, the at least one z. B. bow-shaped guide element 5, the Guide ring 10 and this as a solenoid assembly identifiable arrangement in the circumferential direction to the outside completely enclosing plastic jacket 50. The tubular plastic jacket 50 includes the conventional trained connector 51, for example two Has contact pins 52, the electrical excitation of the Serve solenoid 1. These contact pins 52 extend out of the bobbin 3 up to the connector 51.

The plastic jacket 50 is shaped so that an axial extending inner through opening 54 is formed. The inner through opening 54 of the plastic part 60 not completely due to the inside diameter of the Plastic jacket 50 set, but also by the Inner diameter of the upper end 6 of the guide element 5, the Inner diameter of the bobbin 3 and the Inner diameter of the guide ring 10. Corresponding to that already described minimal differences in the inner diameter The components 3, 5 and 10 result in a multiple easy stepped through opening 54 of the plastic part 60. Outside of the solenoid assembly, the diameter of the Through opening 54 through the plastic of the Plastic sheath 50 set, the inner diameter of the upstream of the solenoid 1 Opening area 55 is larger than the inside diameter of the downstream of the solenoid 1 opening area 56th

The plastic jacket 50 encloses the solenoid assembly not only in the circumferential direction and in the axial direction, but it also extends in the area of at least a guide element 5 between such a guide element 5 and the magnet coil 1 or the coil body 3. Immediately is above the bobbin 3. the plastic jacket 50 on the through opening 54 executed such that one in the Through opening 54 protruding, z. B. by 360 ° circumferential locking element 58 the cross section of the Through opening 54 slightly reduced. This locking element 58 can in the form of a circumferential nose, an inner bead or an inner collar and an angular or have a rounded contour. Likewise, several are over the circumference of the through opening 54 arranged locking lugs conceivable. The outer contour of the plastic jacket 50 is the adjusted the desired installation conditions, z. B. on an annular groove 59 at the lower end of the plastic jacket 50 is provided, into which a sealing ring 62 (Figure 1) can be inserted is.

The formation of such a plastic part 60 with the Latching element 58 according to FIG. 2 enables one for Fuel injectors novel and simplified Assembly. The parts that conduct the magnetic flux Guide element 5 and guide ring 10 are first on the Coil body 3 with the magnet coil 1, for example a clip connection or firmly connected by welding points. This solenoid assembly is subsequently made with plastic encapsulated, so that the already described in detail Contour of the plastic part 60 arises. The inner through opening 54 achieved by Plastic extrusion tool a mandrel is provided which an inner valve part 70 shown in FIG. 3 simulated.

The one shown in FIG. 3, separate from the plastic part 60 manufactured and adjusted valve part 70 corresponds to the inner assembly of the shown in Figure 1 Fuel injector. The valve part 70 comprises mainly the components core 2, fuel filter 40, Adjustment sleeve 39, return spring 33, valve needle 28 with Valve closing body 30, armature 24, sleeve 18 and Valve seat body 25 with spray hole disk 26. The individual Components work together in the manner described above or are in accordance with those previously made with reference to FIG Explanations linked.

Through the use of the relatively cheap sleeve 18, it becomes possible on turned parts common in injectors, such as Valve seat support or nozzle holder, which due to their larger outer diameter more voluminous and at the Manufacture are more expensive than the sleeve 18 to do without. The thin-walled sleeve 18 (wall thickness z. B. 0.3 mm) for example by deep drawing, where as a non-magnetic material, e.g. B. a rust-proof CrNi steel is used. As Sheet metal deep drawn part sleeve 18 serves, as already mentioned, due to their great extent to include the Valve seat body 25, the spray plate 26, the Valve needle 28 with the armature 24, the return spring 33 and at least partially of core 2 and consequently also of Stop area of anchor 24 and core 2 to limit the Stroke. The sleeve 18 has at its upper axial end for example, a slightly radially outward curve Peripheral edge 64. The peripheral edge 64 arises from the Separate the material overflow during deep drawing and serves the Establishing a secure locking connection in the Injector.

After adjusting the stroke and assembling the individual components to valve part 70, the complete valve part 70 is in the Through opening 54 of the plastic part 60 from the upper Opening area 55 inserted here. The valve part 70 and the plastic part 60 go when desired accordingly Insertion length a fixed locking connection. This applies Locking element 58 of the plastic part 60 in a between the Circumferential edge 64 of the sleeve 18 and an outer core shoulder 65 formed groove 66 a. It can be an intervention act snapping or clipping. The groove 66 can also at another point on the circumference of the core 2 be trained. The geometries of the locking element 58 or the groove 66 are provided so that an absolute secure, slip-free connection is created. A release the connection without additional tools is no longer possible. This type of assembly has the great advantage that the high required for plastic molding Overmolding pressure (up to 350 bar) does not cause deformation of the thin-walled sleeve 18 can lead because this is only subsequently together with the entire valve part 70 in Plastic part 60 is integrated.

Claims (11)

1. Fuel injection valve for fuel injection systems of internal combustion engines, with a valve longitudinal axis, with a tubular core (2), with a magnet coil, with at least one conducting element (5, 10) closing an electromagnetic circuit, with a valveclosing body which is part of a valve needle (28) movable axially along the valve's longitudinal axis and which cooperates with a valve seat provided on a valve seat body, with a thin-walled, axially extending, nonmagnetic sleeve (18), in which the valve needle moves axially and which is fixedly connected to the core, the core and the sleeve (18) together delimiting a valve part in the outward direction, and with a plastic injection overmoulding which at least partially surrounds the fuel injection valve, according to one of the Claims 1 to 9,

   in one method step, the independent plastic part (6) with the plastic overmoulding as a plastic casing (50), with the magnet coil (1) and with the at least one conducting element (5, 10), which are surrounded at least partially by the plastic part (6) having an inner passage orifice (54), and,

   in a final method step, the valve part (20) is firmly connected to the plastic part (60) in the passage orifice (54) by means of a catch connection, the article thus produced being used in a fuel injection valve according to one of the Claims 1 - 9.
2. Fuel injection valve according to Claim 1, characterized in that at least one catch element (58) is provided in the passage orifice (54) of the plastic part (60).
3. Fuel injection valve according to Claim 1, characterized in that at least one groove (66) is provided on the circumference of the valve part (70).
4. Fuel injection valve according to Claims 2 and 3, characterized in that the fixed catch connection can be made by the engagement, catching or snapping of the at least one catch element (58) into the at least one groove (66).
5. Fuel injection valve according to Claim 2 or 4, characterized in that the catch element (58) is a peripheral catch nose projecting into the passage orifice (54).
6. Fuel injection valve according to Claim 2 or 4, characterized in that the at least one catch element (58) is a plurality of catch noses arranged over the circumference of the passage orifice (54).
7. Fuel injection valve according to Claim 1 or 3, characterized in that the sleeve (18) has, at its upper end, a peripheral edge (64) which partially delimits a groove (66) on the outer circumference of the valve part (70).
8. Fuel injection valve according to Claim 1 or 3, characterized in that the at least one groove (66) is provided on the circumference of the core (2).
9. Fuel injection valve according to Claim 1, characterized in that the sleeve (18) of the valve part (70) constitutes a deep-drawn sheet-metal part.
10. Method for production of a fuel injection valve for fuel injection systems of internal combustion engines, with a valve longitudinal axis (16), with a tubular core (2), with a magnet coil (1), with at least one conducting element. (5, 10) closing an electromagnetic circuit, with a valve-closing body (30) which is part of a valve needle (28) movable axially along the valve's longitudinal axis (16) and which cooperates with a valve seat provided on a valve seat body (25), with a thin-walled, axially extending, nonmagnetic sleeve (18), in which the valve needle (28) moves axially and which is fixedly connected to the core (2), the core (2) and the sleeve (18) together delimiting a valve part (70) in the outward direction, and with a plastic injection overmoulding (50) which at least partially surrounds the fuel injection valve, according to one of the Claims 1 to 9,

    in one method step, the independent valve part (70) being produced,

       characterized in that

    in a further method step, an independent plastic part (60) with the plastic overmoulding as a plastic casing (50), with the magnet coil (1) and with the at least one conducting element (5, 10), which are surrounded at least partially by the plastic casing (50) is produced, the plastic part (60) having an inner passage orifice (54), and,

    in a final method step, the valve part (20) is firmly connected to the plastic part (60) in the passage orifice (54) by means of a catch connection, the article thus produced being used in a fuel injection valve according to one of the Claims 1 - 9.
11. Method according to Claim 10, characterized in that the catch connection is made by the engagement, catching or snapping of the valve part (70) in the plastic part (60).

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