EP1195516B1 - Fuel injection valve - Google Patents

Description

State of the art

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

From DE 196 25 059 A1 a fuel injection valve is known, which has a plurality of fuel channels in a flow path of the fuel from a fuel inlet to a spray orifice whose cross section determines the amount of fuel sprayed off per unit of time at a given fuel pressure. In order to influence the fuel distribution in a sprayed-off fuel cloud, at least a part of the fuel channels is aligned so that the fuel jets emerging from them are sprayed directly through the injection orifice.

A disadvantage of the fuel injection valve known from the above document is in particular that the fuel channels start in a plane perpendicular to the flow direction of the fuel, the openings are thus arranged on a circular line around a valve needle guide connected to the valve seat carrier. As a result, the quantity of fuel flowing through the fuel injection valve can not be metered precisely enough when the valve closing body is lifted off the sealing seat. In particular the ratio of maximum sprayed amount of fuel to minimally abgespritzter amount of fuel relatively small.

Further, the number of wells is not sufficient to produce a sufficiently homogeneous fuel cloud that meets the stoichiometric requirements for complete combustion. This is additionally reinforced by the large diameter of the fuel channels.

US-A-5823161 discloses a fuel injector for an internal combustion engine which includes a high pressure fuel pump that pumps fuel from a low pressure chamber via a supply line to a high pressure plenum communicating via high pressure lines to the individual injectors incorporated into the high pressure fuel pump Protrude combustion chamber. In order to enable variable injection cross-sections at the injection valves for this system, these injection valves are designed as injection valves with an outwardly opening valve element, via the controllable opening movement in the direction of the combustion chamber, a variable injection cross section can be set to the injection valve. In a valve needle guide, two rows of injection openings are provided axially one above the other. The rows of injection openings are arranged such that the first lower row near the combustion chamber is opened first while the second upper row opens only after another valve needle lift.

EP-A-0789142 discloses a mechanism for a variable number of injection ports of a fuel injector having a plurality of injection ports whose diameter is smaller than that of the conventional injection ports in a cylindrical portion formed at a lower end part of the injection nozzle. On the other hand, these injection ports are again formed such that their total opening area becomes larger than that of the conventional injection ports. Since the injection openings are configured to be all closed on an outer circumferential surface of the needle valve when the valve needle is engaged with the seat, little or no dripping occurs.

Advantages of the invention

The fuel injection valve according to the invention with the characterizing features of the main claim has the advantage that any characteristic can be generated by the arrangement of the fuel channels or their number, so that the Zumeßverhalten the fuel injection valve is improved in relation to the opening and closing times.

The measures listed in the dependent claims advantageous developments of the fuel injection valve specified in the main claim are possible.

The hollow cylindrical shape of the valve needle guide is easy to prepare and can either be made in one piece with the valve seat carrier or attached thereto.

The leadership of the valve closing body in the valve needle guide has in addition to the improvement and control of Zumeßeigenschaften a stabilizing effect on the stroke of the valve needle, since lateral offsets are excluded. The valve closing body can be placed very precisely on the sealing seat after the closing process.

The gaps in the rows of fuel channels provide for a freely selectable injection dynamics and a shapable jet pattern, which can be influenced by the targeted introduction of fuel channels at individual points of the valve needle guide.

By arranging the fuel channels with a tangential component relative to the center axis of the fuel injection valve, the fuel receives a twist, which ensures a good treatment of the mixture cloud.

drawing

Fig. 1

einen schematischen Schnitt durch ein Ausführungsbeispiel eines Brennstoffeinspritzventils gemäß dem Stand der Technik,

Fig. 2

einen schematischen Ausschnitt durch das Brennstoffeinspritzventil im Bereich II in Fig. 1,

Fig. 3

einen schematischen Schnitt entlang der Linie III-III in Fig. 2,

Fig. 4A-B

ein zweites Ausführungsbeispiel eines nicht erfindungsgemäßen Brennstoffeinspritzventils entsprechend einem Schnitt entlang der Linie III-III in Fig. 2 mit der dazugehörigen Kennlinie,

Fig. 5A-B

ein erstes Ausführungsbeispiel eines erfindungsgemäßen Brennstoffeinspritzventils entsprechend einem Schnitt entlang der Linie III-III in Fig. 2 mit der dazugehörigen Kennlinie,

Fig. 6A-B

ein zweites Ausführungsbeispiel eines erfindungsgemäßen Brennstoffeinspritzventils entsprechend einem Schnitt entlang der Linie III-III in Fig. 2 mit der dazugehörigen Kennlinie, und

Fig. 7A-B

ein drittes Ausführungsbeispiel eines erfindungsgemäßen Brennstoffeinspritzventils entsprechend einem Schnitt entlang der Linie III-III in Fig. 2 mit der dazugehörigen Kennlinie.

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

FIG. 2 shows a schematic section through an exemplary embodiment of a fuel injection valve according to the prior art, FIG.

Fig. 2

a schematic section through the fuel injection valve in area II in Fig. 1,

Fig. 3

a schematic section along the line III-III in Fig. 2,

Fig. 4A-B

A second embodiment of a non-inventive fuel injection valve according to a section along the line III-III in Figure 2 with the associated characteristic,

Fig. 5A-B

a first embodiment of a fuel injection valve according to the invention corresponding to a section along the line III-III in Fig. 2 with the associated characteristic,

Fig. 6A-B

a second embodiment of a fuel injection valve according to the invention corresponding to a section along the line III-III in Figure 2 with the associated characteristic, and

Fig. 7A-B

a third embodiment of a fuel injection valve according to the invention corresponding to a section along the line III-III in Fig. 2 with the associated characteristic.

Description of the embodiments

Before with reference to the figures 5 to 7 embodiments of a fuel injection valve 1 according to the invention will be described briefly to better understand the invention with reference to FIG. 1, an already known, apart from the inventive measures to the embodiments of the same fuel injector 1 with respect to its essential components briefly explained ,

The fuel injection valve 1 is embodied in the form of a fuel injection valve for fuel injection systems of mixture-compression spark-ignition internal combustion engines. The fuel injection valve 1 is suitable in particular for the direct injection of fuel into a combustion chamber, not shown, of an internal combustion engine.

The fuel injection valve 1 consists of a nozzle body 2, in which a valve needle 3 is arranged. The valve needle 3 is operatively connected to a valve closing body 4, which cooperates with a valve seat body 6 arranged on a valve seat body 5 to form a sealing seat. The fuel injection valve 1 in the exemplary embodiment is an inwardly opening fuel injection valve 1 which has an injection opening 7. The nozzle body 2 is sealed by a seal 8 against the outer pole 9 of a magnetic coil 10. The magnetic coil 10 is encapsulated in a coil housing 11 and wound on a bobbin 12, which rests against an inner pole 13 of the magnetic coil 10. The inner pole 13 and the outer pole 9 are through a gap 26th separated from each other and are based on a connecting member 29. The magnetic coil 10 is energized via a line 19 from a via an electrical plug contact 17 can be supplied with electric current. The plug contact 17 is surrounded by a plastic casing 18, which may be molded on the inner pole 13.

The valve needle 3 is guided in a valve needle guide 14, which is designed disk-shaped. On the other side of the dial 15 is an armature 20. This is frictionally connected via a first flange 21 with the valve needle 3 in connection, which is connected by a weld 22 with the first flange 21. On the first flange 21, a return spring 23 is supported, which is brought in the present design of the fuel injection valve 1 by a sleeve 24 to bias.

A second flange 31, which is connected to the valve needle 3 via a weld 33, serves as a lower anchor stop. An elastic intermediate ring 32, which rests on the second flange 31, avoids bouncing when closing the fuel injection valve. 1

In the valve needle guide 14, the armature 20 and the valve seat body 5 are fuel passages 30a to 30c, which conduct the fuel, which is supplied via a central fuel supply 16 and filtered by a filter element 25, to the ejection opening 7. The fuel injection valve 1 is sealed by a seal 28 against a fuel line, not shown.

In the idle state of the fuel injection valve 1, the armature 20 is acted upon by the return spring 23 counter to its stroke direction so that the valve closing body 4 is held on the valve seat 6 in sealing engagement. Upon excitation of the solenoid coil 10, this builds up a magnetic field, which moves the armature 20 against the spring force of the return spring 23 in the stroke direction, the stroke being predetermined by a working gap 27 located in the rest position between the inner pole 12 and the armature 20. The armature 20 takes the flange 21, which is welded to the valve needle 3, also in the stroke direction with. The valve closing body 4, which is in operative connection with the valve needle 3, lifts off from the valve seat surface 6 and the fuel guided via the fuel channels 30a to 30c to the injection opening 7 is hosed down.

If the coil current is turned off, the armature 20 drops after sufficient degradation of the magnetic field by the pressure of the return spring 23 from the inner pole 13, whereby the standing with the valve needle 3 in operative connection flange 21 moves against the stroke direction. The valve needle 3 is thereby moved in the same direction, whereby the valve closing body 4 touches on the valve seat surface 6 and the fuel injection valve 1 is closed.

FIG. 2 shows an excerpted sectional view of the detail of the fuel injection valve 1, indicated by II in FIG. 1.

The illustrated in Fig. 2 embodiment of a non-inventive fuel injection valve 1 has a valve needle guide 31, which is formed on an inlet-side end face 32 of the valve seat body 5. The valve needle guide 31 may be integrally formed with the valve seat body 5 or be connected to the valve seat body 5, for example, by welding, soldering or similar methods. The valve needle guide 31 is formed as a hollow cylinder.

In the present embodiment, the valve needle 3 has a spherical valve closing body 4. The valve closing body 4 forms with the formed on the valve seat body 5 valve seat surface 6 a Sealing seat. The valve closing body 4 is guided by the valve needle guide 31, wherein the valve closing body 4 rests with a guide line 33 on an inner wall 38 of the valve needle guide 31. Between the guide line 33 and the sealing seat, a plurality of rows 34 of fuel channels 35 are arranged in the valve needle guide 31, which extend from a radially outer side 36 of the valve needle guide 31 to a radially inner side 39.

The fuel channels 35 may either be perpendicular to a central axis 37 of the fuel injection valve 1 or inclined at an angle α relative to the central axis 37 perpendicular orientation in the outflow direction. The latter is hydrodynamically cheaper.

As soon as the valve needle 3 is moved counter to the flow direction of the fuel by actuation of the fuel injection valve 1, the fuel channels 35 of the rows 34 are released. Fuel flows from a radially outer side 36 of the valve needle guide 31 through the fuel channels 35 in the direction of sealing seat.

By a corresponding arrangement of the fuel channels 35, a characteristic which represents the dynamic flow of fuel through the fuel injection valve in response to a stroke of the valve needle 3, can be adjusted or modeled. By appropriate stroke adjustment of the valve needle 3 then flows as much fuel through the fuel channels 35, as is necessary in the context of the flow accuracy to be achieved.

FIG. 3 shows a schematic section along the line III - III in FIG. 2 through the valve needle guide 31 in the region of the fuel channels 35. The fuel channels 35 of the adjacent rows 34 are arranged circumferentially staggered with respect to one another in order to produce the most homogeneous possible mixture cloud. However, the fuel channels 35 may also be arranged without circumferential offset. To the required To achieve metering accuracy, the fuel channels 35 should have a very small diameter, for example less than 100 μm, in particular less than or equal to 70 μm. The production of such small-caliber holes can be done for example by means of laser processing.

Since the fuel channels 35 for generating a twist have a tangential component relative to the central axis 37 of the fuel injection valve 1, the cross section of the fuel channels 35 in Fig. 3 appears oval. The orientation of the tangential components of the fuel channels 35 can be in the same direction relative to the remaining rows 34 in each row 34. The present embodiment of a non-inventive fuel injection valve 1 thus combines the spin conditioning with a refinement of the metered amount of fuel.

FIGS. 5 to 7 show, in the same sectional plane as FIG. 3, exemplary embodiments of the fuel injection valve 1 according to the invention with different arrangements of the fuel channels 35 in each case in conjunction with the characteristic curve generated by the corresponding arrangement of fuel channels 35.

The characteristics represent the relationship between the dynamic flow rate through the fuel injector 1 during the opening operation in response to Ventilnadelhub. With a uniform arrangement of the fuel channels 35, the flow increases with the stroke of the valve needle 3 is relatively uniform, and then go into a constant saturation value, which represents the static flow through the fuel injection valve 1 in the open state.

The embodiment shown in Fig. 4A has a similar arrangement of the fuel channels 35 as that shown in Fig. 3, but the fuel channels 35 are not circumferentially offset from each other, but arranged in a grid-like structure directly below each other. The characteristic curves of the exemplary embodiments illustrated in FIG. 3 and FIG. 4A correspond to the characteristic curve shown schematically in FIG. 4B.

According to the invention, the arrangement of the fuel channels 35 changed by z. B. the rows 34 are no longer completely equipped with fuel channels 35, but have gaps 40, the characteristic changes. For example, as shown in Fig. 5A, when each second fuel passage 35 is discharged in two rows 34 closer to the seal seat, the characteristic is deformed in an S-shape as shown in Fig. 5B. Thus, at the beginning of the opening process, a smaller quantity of fuel initially flows through the fuel injection valve 1 until the valve closing body 4 also releases the complete rows 34 and, after a steeper increase than in FIG. 4B, the saturation value is reached.

The embodiment shown in Fig. 6A dispenses with further fuel channels 35, so that the gaps 40 are circumferentially longer, and also the number of rows 34 is reduced. Due to the now very isolated fuel channels 35 flows at the beginning of the opening process only a very small amount of fuel, which then increases when releasing the remaining rows 34 very quickly to the saturation value and almost reaches a stepped course, as shown in Fig. 6B.

Also, the embodiment shown in Fig. 7A leads to a rapid increase in the fuel flow, since the closer to the sealing seat rows 34 of fuel channels 35 are still fully occupied, while the remaining rows 34 only isolated fuel channels 35 or 40 large gaps or have Fuel channels 35 are completely missing. The associated characteristic curve is shown in FIG. 7B.

In particular, the characteristics shown in Figs. 6B and 7B have the advantage that the desired amount of fuel can be metered in a short period of time and the flow is rapidly saturated, whereby the opening and closing times of the fuel injection valve 1 can be favorably influenced.

All embodiments have in common that a very small minimum amount of fuel q _min can be achieved, whereby the ratio q _max / q _{min of} the maximum injectable amount of fuel q _max to the minimum injectable amount of fuel q _{min is} increased.

The invention is not limited to the illustrated embodiment and z. B. also applicable to fuel injectors 1 with piezoelectric and magnetostrictive actuators or any arrangements of fuel channels 35.

LIST OF REFERENCE NUMBERS

1

Fuel injector

2

nozzle body

3

valve needle

4

Valve closing body

5

Valve seat body

6

Valve seat

7

spray opening

8th

poetry

9

outer pole

10

solenoid

11

coil housing

12

coil carrier

13

pole

14

Valve needle guide

15

Focusing

16

central fuel supply

17

plug contact

18

Plastic sheathing

19

electrical line

20

anchor

21

flange

22

Weld

23

Return spring

24

shell

25

filter element

26

throttle gap

27

working gap

28

poetry

29

connecting member

30a-30c

fuel channel

31

Valve needle guide

32

inlet-side end face of the valve seat carrier. 5

33

leader line

34

string

35

fuel channels

36

radially outer side of the valve needle guide 31st

37

Center axis of the fuel injection valve 1

38

Inner wall of the valve needle guide 31st

39

radially inner side of the valve needle guide 31

40

Gaps between the fuel channels 35

Claims (10)

1. Fuel injection valve (1), in particular for the direct injection of fuel into a combustion space of an internal combustion engine, with an actuator (10) for actuating a valve needle (3), the valve needle (3) having, at an injection-side end, a valve-closing body (4) which, together with a valve-seat surface (6) formed on a valve-seat body (5), forms a sealing seat, and with fuel ducts (35) which are arranged in a valve-needle guide (31) connected to or produced in one piece with the valve-seat body (5), the fuel ducts (35) being arranged in a plurality of rows (34) circumferentially in the valve-needle guide (31), the number of fuel ducts (35) and their position in relation to one another being selected such that a characteristic curve representing a dynamic fuel flow (q_dyn) through the fuel injection valve (1) as a function of a stroke (h) of the valve needle is thereby set, characterized in that at least one of the rows is occupied completely by fuel ducts (35), and in that at least one of the rows (34) has gaps (40) between the fuel ducts (35).
2. Fuel injection valve according to Claim 1, characterized in that the valve-needle guide (31) is formed on an inflow-side end face (32) of the valve-seat body (5).
3. Fuel injection valve according to Claim 2, characterized in that the valve-needle guide (31) extends hollow-cylindrically from the end face (32) of the valve-seat body (5).
4. Fuel injection valve according to Claim 3, characterized in that the valve-closing body (4) is shaped such that it bears, in the region of a guiding line (33), against an inner wall (38) of the valve-needle guide (31).
5. Fuel injection valve according to one of Claims 1 to 4, characterized in that the fuel ducts (35) have a tangential component with respect to a mid-axis (37) of the fuel injection valve (1).
6. Fuel injection valve according to Claim 5, characterized in that the tangential components of the rows (34) are oriented codirectionally.
7. Fuel injection valve according to one of Claims 1 to 6, characterized in that the rows (34) which have gaps (40) are arranged nearer to the sealing seat than the rows which have no gaps (40).
8. Fuel injection valve according to one of Claims 1 to 6, characterized in that the rows (34) which have gaps (40) are further away from the sealing seat than the rows which have no gaps (40).
9. Fuel injection valve according to one of Claims 1 to 8, characterized in that the gaps (40) are arranged so as to be offset with respect to one another circumferentially.
10. Fuel injection valve according to one of Claims 1 to 9, characterized in that the gaps of different rows (34) are dimensioned differently with regard to number and/or to circumferential length.

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