EP1045974B1 - Fuel injection valve - Google Patents

Description

State of the art

The invention is based on a fuel injector according to the genus of the main claim.

A fuel injector is already known from US Pat. No. 5,299,776 known according to the preamble of claim 1. The Fuel injector has one with a valve needle connected valve closing body with one on one Valve seat body designed valve seat surface to a Sealing seat interacts. For electromagnetic actuation of the fuel injector is a solenoid provided that cooperates with an anchor attached to the Valve needle between one the movement of the armature in the Stroke direction of the valve needle limiting first stop and one the movement of the armature against the stroke direction limiting second stop is movable. That through the two stops fixed axial movement of the Within certain limits, Ankers decouples the inert mass of the valve needle and the valve closing body on the one hand and the inertial mass of the anchor on the other. This will cause the valve closing body to rebound from the valve closing surface when the fuel injector closes counteracted within certain limits. Guide the valve needle or valve closing body to an uncontrolled, brief opening of the fuel injector and thus to a non-reproducible Dosing amount of fuel and to an uncontrolled Injection behavior. However, since the axial position of the armature with regard to the valve needle by the free mobility of the Anchor is completely undefined in relation to the valve needle, bouncers are avoided to a limited extent. In particular is in the construction known from US-PS 5,299,776 the fuel injector not avoided that Anchor during the closing movement of the fuel injector on the stop facing the valve closing body strikes and his impulse abruptly on the valve needle and thus transfers to the valve closing body. This Sudden impulse transmission can cause additional bouncing Cause valve closing body.

To the impact of the armature on the valve closing body To dampen facing stop, it is, for example the US-PS 4,766,405 known between the anchor and the Stop a damping body made of an elastomer material, for example made of rubber. Rubber materials have the disadvantage, however, that these in their Damping behavior are strongly temperature-dependent and that Damping effect decreases with an increase in temperature. Furthermore, the long-term stability of elastomer materials limited, especially if this with that of the fuel injector sprayed fuel in contact come. The aging of the elastomer material can Limit the service life of the fuel injector. The Installation of a damping disc made of an elastomer material is complex. It is just as complex, the elastomer material vulcanize on the anchor or on the stop. A targeted adjustment of the damping properties is also not possible.

From US-PS 5,236,173 it is known between the valve seat body and a valve seat support on which the Valve seat body is mounted, a damping spring in the form a disc spring to ensure that the Valve closing body on the on the valve seat body trained valve seat surface strikes softly. This kind the damping has the disadvantage, however, that the valve seat body after striking the valve closing body in Spray direction swings through while the valve closing body either stops or due to the pulse reversal even from the valve seat body against the spray direction moved back. Valve bumpers can therefore this design of the fuel injector even in occur to an increased extent, so that this type of Damping has not proven.

From US-PS 5,114,077 is already a Fuel injection valve for fuel injection systems from Internal combustion engines known to have an electromagnetic Has a circle that includes an excitable solenoid and actuatable anchor includes. The anchor is through that Solenoid in one stroke direction against a return spring acted upon. The anchor is on a valve pin arranged, the valve needle with a Valve closing body is connected. The anchor is between one connected to the valve needle, the movement of the armature in the stroke direction limiting first stop and one connected to the valve needle, the movement of the Anchor against the stroke direction limiting second Movable stop. Between the second lower stop and the armature is arranged a plate spring. The lower end face of the anchor and the upper end face of the second attack run parallel to each other in the right angle to the valve longitudinal axis so that the disc spring is clamped between these two flat end faces.

Advantages of the invention

The fuel injector according to the invention with the characteristic In contrast, features of the main claim the advantage that the fuel injector is satisfactory Way debounced. Furthermore, there is a high one Long-term stability, because the damping spring against one Elastomer material has a long service life and especially not from the fuel over time is decomposed. Furthermore, the damping spring is compared to an elastomer material can be assembled without any special effort and the damping effect is independent of temperature. Is too a targeted adjustment of the damping properties an appropriate choice of material and shape Damping spring, the angle of attack of the damping spring compared to the stop and the anchor as well as the preload the damping spring possible.

There is a between the anchor and the stop Squeezing flow of itself in the gap between the armature and the fuel. This squeezing flow leads to additional damping.

According to the invention, the stop is convex and the opposite one The face of the anchor is concave be formed or vice versa, the stop can be concave and the opposite end face of the anchor is convex be trained. This creates a gap between the armature and the stop an inclination with respect to the longitudinal axis of the Valve needle, and the damping by the squeezing flow of the Fuel is improved. Furthermore, the concave or convex formation of the stop and the opposite End face of the anchor a disc spring with a flat spring washer that are simple and is inexpensive to manufacture. In addition to the level Spring washer can be a conical or disc spring have curved spring washer, which reduces the damping effect is still improved.

By the measures listed in the subclaims advantageous developments and improvements in Main claim specified fuel injector possible.

The damping spring is preferably a plate spring surrounds the valve needle in a ring. Through the disc spring a compact damping component is created, which in the Gap between the anchor and the stop can be integrated can. The assembly of the disc spring is also extreme simple; it is only on before installing the anchor to slide on the valve needle.

Alternatively, it is possible to stop and the opposite To form the end face of the armature, wherein then a disc spring with a conical or arched Spring washer is used. You can also use two conical or arched spring washers are used axially adjacent to each other so that either their convex sides or their concave sides to each other are facing. The two spring washers can have one Connecting strap to be connected what the Assembly simplified. Furthermore, the two spring washers then, for example, by punching from a part Metal strips are made.

To set the damping characteristic of the disc spring, the spring washers can have openings on the one hand have an influence on the spring constant of the spring washers and on the other hand the squeezing flow of the fuel in the Affect the gap between the anchor and the stop.

Between which the movement of the armature in the stroke direction limiting stop and the anchor can be another Damping spring may be arranged to prevent the Anchor strikes hard at this stop and valve bouncer caused.

drawing

Fig. 1

ein Ausführungsbeispiel eines erfindungsgemäßen Brennstoffeinspritzventils in einer geschnittenen Darstellung;

Fig. 2

den Bereich X in Fig. 1 in einer vergrößerten Darstellung;

Fig. 3

den Bereich X in Fig. 1 entsprechend einem abgewandelten zweiten Ausführungsbeispiel;

Fig. 4

den Bereich X in Fig. 1 entsprechend einem abgewandelten dritten Beispiel, das nicht unter Anspruch 1 fällt;

Fig. 5

den Bereich X in Fig. 1 entsprechend einem abgewandelten vierten Beispiel, das nicht unter Anspruch 1 fällt und

Fig. 6

den Bereich X in Fig. 1 entsprechend einem abgewandelten fünften Beispiel, das nicht unter Anspruch 1 fällt.

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

Fig. 1

an embodiment of a fuel injector according to the invention in a sectional view;

Fig. 2

the area X in Figure 1 in an enlarged view.

Fig. 3

the area X in FIG. 1 in accordance with a modified second exemplary embodiment;

Fig. 4

the area X in Figure 1 according to a modified third example, which does not fall under claim 1;

Fig. 5

the area X in Fig. 1 according to a modified fourth example, which does not fall under claim 1 and

Fig. 6

the area X in Fig. 1 according to a modified fifth example, which does not fall under claim 1.

Description of the embodiments

Fig. 1 shows a partially cut representation a first embodiment of an inventive Fuel injector 1. The fuel injector 1 is used to inject fuel in a mixture-compressing, spark ignition internal combustion engine. The The illustrated embodiment is a high-pressure injection valve for direct fuel injection, in particular of gasoline, in the combustion chamber of the internal combustion engine.

The fuel injector 1 has one in the embodiment integrally connected to a valve needle 2 Valve closing body 3, which with a valve seat body 4 trained valve seat surface into one Sealing seat interacts. The valve seat body 4 is with connected to a tubular valve seat support 5, which in a Location bore of a cylinder head of the internal combustion engine is insertable and against the receiving bore by means of a Seal 6 is sealed. The valve seat support 5 is on its inlet end 7 in a longitudinal bore 8 of a Housing body 9 inserted and against the housing body 9 sealed by means of a sealing ring 10. The inlet side End 7 of the valve seat support 5 is by means of a Threaded ring 11 biased, between a stage 12 of the housing body 9 and an end face 13 of the inlet-side end 7 of the valve seat support 5 a stroke adjusting disc 14 is clamped.

For electromagnetic actuation of the fuel injector 1 serves a magnetic coil 15, which on a Coil carrier 16 is wound. With electrical excitation Solenoid 15 becomes an armature 17 in Fig. 1 upwards pulled until its inlet end face 19 at one Level 18 of the housing body 9 is applied. The gap width between the upstream end face 19 of the armature 17th and the level 18 of the housing body 9 determines the Valve stroke of the fuel injector 1. During its stroke movement takes the anchor 17 due to the plant of his upstream end face 19 on a first Stop body 20 formed first stop 21 with the first stop body 20 connected valve needle 2 and the valve closing body 3 connected to the valve needle 2 With. The vantil needle 2 is with the first Stop body 20 welded by a weld 22. The The valve needle 2 moves against a return spring 23 between an adjusting sleeve 24 and the first Stop body 20 is clamped.

The fuel flows through an axial bore 30 Housing body 9 and an axial bore provided in the armature 17 31 as well as in a guide disk 32 provided axial bores 33 in an axial bore 34 of the Valve seat support 5 and from there to the not shown Fuel injector 1 seat.

The armature 17 is between the first stop 21 of the first Stop body 20 and one on a second stop body 25 trained second stop 26 movable, the Armature 17 by a contact spring 27 in the rest position the first stop 21 is held in contact so that a gap between the armature 17 and the second stop 26 arises, which is a certain movement play of the armature 17th allowed. The second stop body 25 is by means of a Weld 28 is attached to the valve needle 2.

By the created between the stops 21 and 26 Movement play of the armature 17 is a decoupling of the inert masses of the armature 17 on the one hand and the valve needle 2 and the valve closing body 3 on the other hand. at the closing movement of the fuel injector 1 strikes on the valve seat surface, not shown, therefore only the Inert mass of the valve closing body 3 and the valve needle 2 on, the anchor 17 when the Valve closing body 3 on the valve closing surface is not is decelerated abruptly, but towards the second stop 26 moves on. By decoupling the The armature 17 from the valve needle 2 is the dynamics of the fuel injector 1 improved. However, it must be ensured be that striking the spray-side End face 29 of the armature 17 on the second stop 26 does not cause valve bouncing. This is through the Measure achieved according to the invention.

2 is the area marked X in FIG. 1 partially shown enlarged, whereby already described Provide elements with matching reference symbols are to facilitate the assignment.

2 shows the valve needle 2, which is on the valve needle 2 second stop body welded by means of the weld seam 28 25 with its second stop 26, the anchor 17 with its spray-side, the second stop 26 opposite Face 29 and the in the rest position of the Fuel injector 1 between the spray side End face 29 of the armature 17 and the stop 26 of the second Stop body 25 formed gap 40 recognizable. According to the invention is in the gap 40 between the second stop 26 and the spray-side end face 29 the armature 17 is a damping spring, which in the present Embodiment as a valve needle 2 annular enclosing plate spring 41 is formed.

In the embodiment shown in Fig. 2 is the spray-side end face 29 of the armature 17 conically convex formed while a stop 26 forming End face 42 of the second stop body 25 is conically concave is trained. Alternatively, the end faces 29 and 42 can also be arched convex or concave. there the end face 29 could also be concave if then conversely the end face 42 of the second Stop body 25 is convex. The convex or concave design of the end faces 29 and 42 enables a plate spring 41 with a flat spring washer 43 use.

The damping spring 41 dampens the stop of the armature 17 on the second stop 26, so that the armature 17 on the second stop 26 relatively soft and cushioned strikes. The damping effect is based on one hand elastic deformation of the plate spring 41; on the other hand in the idle state of the fuel injector 1 in the gap 40 displaced fuel displaced from the gap 40, so that a squeezing flow of the fuel arises, too dampens the armature movement.

If the plate spring 41 not only striking the armature 17 dampens on the second stop 26, but the armature 17th so far that the anchor 16 at rest on the the first stop 22 rests flush, the contact spring can, if necessary 27 omitted.

Fig. 3 also shows that marked X in Fig. 1 Section of the fuel injector 1, however, accordingly a second, alternative embodiment.

The difference to the embodiment shown in FIG. 2 is that the plate spring 41 not only the flat spring washer 43, but also from a conical spring washer 44. Both spring washers 43 and 44 surround the valve needle 2. The second Spring washer 44 could also be curved. A convex side 45 of the conical or curved spring washer 44 faces the convex end face 29 of the armature 17. Would be the end face 42 of the second stop body 25 instead the end face 29 of the armature 17 is convex, that would be the conical or curved spring washer 44 accordingly this convex end face 42 of the second stop body 25 facing. Due to the two-disc design of the disc spring 41 is achieved that the armature 17 in its downward movement comes into contact with the plate spring 41 earlier and therefore damping or cushioning the armature movement over a larger movement distance of the armature 17 can, which results in an even softer stroke.

Fig. 4 shows the section marked X in Fig. 1 of fuel injector 1 according to an alternative third embodiment.

The example shown in Fig. 4 is both the spray-side, the second stop body 25 opposite end face 29 of the armature 17 as well as the end face 42 of the second, opposite armature 17 Stop body 25 formed flat, which is manufacturing technology is easier to implement. A spring washer is corresponding 45 of the plate spring 41 is conical or curved, so that the spring washer 45 with the end face 25th the armature 17 comes into engagement before the armature 17 to the second stop 26 strikes.

FIG. 5 shows the area marked X in FIG. 1 in FIG corresponding to an enlarged, excerpt a fourth alternative example. The Difference to that shown in Fig. 4 Example is that the plate spring 41st not just from a first conical or arched one Spring washer 45 but also from a second conical or arched spring washer 47. Are the two conical or curved spring washers 46 and 47 axially adjacent to each other so that concave sides 48th and 49 of the spring washers 46 and 47 are facing each other. Alternatively, the one in Fig. 6 is on the left fifth example shown the two conical or arched spring washers 46 and 47 axially arranged so that convex sides 50 and 51 of the spring washers 46 and 47 are facing each other. at the embodiments shown in FIGS. 5 and 6 is achieved that the axial length of movement over which the Disc spring 41 during the downward movement of the armature 17 on the abutment-side end face 29 of armature 17 rests, is increased and thus the damping path is extended. This results in a softer stop of the armature 17 on the second stop 26 achieved.

The one shown in Fig. 6 on the right side sixth example is another Difference to that shown in Fig. 5 Example in that the two spring washers 46 and 47 to one another by means of a connecting strap 52 are connected. This facilitates the assembly of the disc spring 41. Furthermore, the two spring washers 46 and 47 can then also in one piece from a sheet metal strip, for example Stamping are produced, two of which are the spring washers 46 and 47 rings are punched out, which by a the connecting tab 52 forming web are connected.

The plate spring 41 preferably consists of one rusting spring material, for example an iron and / or Copper alloy. About the thickness and the Angle of attack of the spring washers 43, 44, 46, 47 can Damping characteristics of the plate spring 41 targeted can be set. The damping characteristic can also by provided in the spring washers 43, 44, 46, 47 Openings are changed. These openings have at the same time an influence on the cross flow of the from the gap 40 displaced fuel, so that this is also a Variation of the damping characteristic results. The disc spring 41 is with a defined bias between the Anchor 17 and the second stop body 25 mounted.

Claims (8)

1. Fuel injection valve (1) for fuel injection systems of internal combustion engines, with a magnet coil (15), with an armature (17) capable of being acted upon by the magnet coil (15) in a lifting direction counter to a return spring (23), and with a valve needle (2) connected to a valve-closing body (3), the armature (17) being moveable between a first stop (21), which is connected to the valve needle (2) and limits the movement of the armature (17) in the lifting direction, and a second stop (26), which is connected to the valve needle (2) and limits the movement of the armature (17) counter to the lifting direction, and with a damping spring (41) which is arranged between the second stop (26) and the armature (17), characterized in that the second stop (26) is formed by one end face (42) of a stop body (25), the said end face being located opposite the armature (17), and in that one end face (29) of the armature (17), the said end face being located opposite the second stop (26), is designed convexly and that end face (42) of the stop body (25) which is located opposite the armature (17) is designed concavely, or in that that end face (29) of the armature (17) which is located opposite the second stop (26) is designed concavely and that end face (42) of the stop body (25) which is located opposite the armature (17) is designed convexly.
2. Fuel injection valve according to Claim 1, characterized in that the damping spring is a cup spring (41) which surrounds the valve needle (2) annularly.
3. Fuel injection valve according to Claim 2, characterized in that the cup spring (41) comprises a planar spring washer (43).
4. Fuel injection valve according to Claim 2 or 3, characterized in that the cup spring (41) has a conical or arched spring washer (44), with a convex side (45) of the conical or arched spring washer (44) facing the convex end face (29, 42) of the armature (17) or of the stop body (25).
5. Fuel injection valve according to Claim 3 or 4, characterized in that the spring washer (43) or spring washers (43, 44) have orifices.
6. Fuel injection valve according to one of Claims 1 to 5, characterized in that a further damping spring is arranged between the first stop (21) and the armature (17) .
7. Fuel injection valve according to Claim 2, characterized in that the cup spring (41) consists of a rust-proof spring material.
8. Fuel injection valve according to Claim 7, characterized in that the spring material is an iron and/or copper alloy.

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