EP1328720A2

EP1328720A2 - Fuel injection valve

Info

Publication number: EP1328720A2
Application number: EP01986747A
Authority: EP
Inventors: Guenter Dantes; Detlef Kowak
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2000-10-13
Filing date: 2001-10-15
Publication date: 2003-07-23
Also published as: DE10050752B4; DE10050752A1; US20030047623A1; WO2002031352A2; US6764027B2; CZ20022032A3; WO2002031352A3; JP2004511702A

Abstract

The invention relates to a fuel injection valve (1), for fuel injection units on internal combustion engines, comprising a valve needle (3) and a valve closing body (4), connected to the above, which co-operates with a valve seat surface (6), arranged on a valve seat body (5), to give a sealing seat and at least one swirl-inducing element arranged in the valve seat body (5) upstream of the sealing seat. One or several swirl channels (36), open to the upstream side (33) of the valve seat body (5), are arranged in the upstream side (33) of the valve seat body (5) as swirl-inducing elements.

Description

2/31352

Fuel injector

State of the art

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

Fuel injection valves in which swirl-generating elements are incorporated in a valve seat body are known, for example, from DE 41 31 499 Cl. The swirl-generating element is designed in the form of grooves which are introduced into the valve seat body and open at an injection opening. ..The amount of fuel to be sprayed is metered through the cross-section of the spray opening. This is arranged either in the valve seat body or in a perforated disk arranged at the downstream end of the fuel injector.

Another fuel injection valve, in which the swirl is generated by grooves, is known from DE 42 31 448 Cl. The swirl-generating elements are located upstream of the sealing seat and are introduced as grooves in a central recess in the valve seat body, which serves as a guide for the valve closing body. The swirl grooves open towards the center axis of the fuel injection valve become channels through the valve closing body, which is preferably spherical closed. This defines a cross section within the swirl channels through which the fuel is metered.

A disadvantage of the fuel injector known from DE 41 31 499 Cl is the arrangement of the swirl generation downstream of the sealing seat. In the case of direct injection fuel injectors in particular, there is a high risk of contamination by coking. In the construction, particular attention should be paid to the robustness of the swirl-generating elements, which limits the design options of the component, since e.g. B. Minimum requirements for material thickness must be met.

Another disadvantage is that the arrangement downstream of the sealing seat forms a dead volume from which fuel can escape after the end of the spraying process. This dripping leads to incomplete and uncontrolled combustion, which produces a high level of pollutants. In addition, the one-piece design of the nozzle body and valve seat body complicates the introduction of the grooves. Any exceedances of component tolerances that occur during production thus lead to the rejection of an expensive component.

In the injection valve known from DE 42 31 448 Cl, the addition of the grooves to swirl channels by the spherical valve closing body is disadvantageous. Due to the spherical geometry of the valve closing body, the swirl grooves are closed to swirl channels only on the circumferential line of the valve closing body. Leakage flow is difficult to prevent as a result, since the component tolerances of several parts add up. This is particularly critical due to the design of the sealing gap as a line. As a result, the metered amount of fuel fluctuates widely. Another disadvantage is the required strong redirection of the fuel flow. This results from the arrangement of the swirl channels on the cylinder wall of the recess, which is used to guide the valve closing body. The subsequent swirl chamber is required to generate a uniform swirled flow. The associated deflection of the flow, however, leads to severe flow losses, which are noticeable in a worsened spray pattern.

During the opening process of the fuel injector, a pre-jet is also formed which has no swirl. The resulting poor atomization leads to poor combustion.

Advantages of the invention

The fuel injector according to the invention with the characterizing feature of the main claim has the advantage that the swirling fuel flow reaches the spray opening without a strong deflection. At the same time, the swirl-generating elements are arranged protected upstream of the sealing seat. The decoupling of the swirl generation from the metering of the fuel to be sprayed is also advantageous for production. The dimensional tolerances of the swirl-generating elements can be selected relatively roughly, which enables the use of inexpensive manufacturing processes.

Advantageous further developments of the fuel injector specified in the main claim are possible through the measures set out in the subclaims.

The adaptation of the fuel injector to customer requirements with regard to to be metered

The amount of fuel and the spray pattern are easily possible. It is done by changing only one component with the The swirl generation can be varied in the axial proportion of the fuel flow. This leads to a change in the cone shell on which the fuel is sprayed off.

The metering quantity is also set while maintaining the unchanged valve seat body, by changing an annular gap which is generated by a shoulder in the valve closing body. In addition to the definition of a metered quantity when the fuel injector is fully open, changing the contour of the shoulder can influence the opening and closing behavior.

An arrangement of the swirl channels on a conical jacket, the angle of which is identical to the angle of the valve seat surface, is also advantageous. As a result of the elimination of strong flow deflection downstream of the swirl generation, there is no loss in the peripheral speed of the fuel on the way to the spray opening.

Another advantage of this is that there is no dead volume downstream of the swirl generation. The formation of a swirl in the fuel flow thus already occurs during the opening process of the fuel injector. The improved

Twist preparation during opening and closing ultimately improves combustion and thus leads to lower pollutant emissions.

drawing

An embodiment of the invention is shown in simplified form in the drawing and explained in more detail in the following description. Show it:

Fig. 1 shows a schematic partial section through. A -t-t - -. -. -, '____. ._! H .- »■}. _* -. , -,, - * -ι ßon FIG. 2 shows a schematic partial section in section II of FIG. 1 of the exemplary embodiment of a fuel injector according to the invention; and 5

3 shows a schematic section along the line III-III in FIG. 2.

Description of the embodiment

D

Before an embodiment of a fuel injector 1 according to the invention is described in more detail with reference to FIGS. 2 and 3, the invention according to the invention should first be understood with reference to FIG. 1 for better understanding of the invention

5 fuel injector 1 will be briefly explained in an overall representation with regard to its essential components.

The fuel injection valve 1 is in the form of a fuel injector 10 ^'1 is - mixture-fuel injection systems of spark ignition

Internal combustion engines. The

Fuel injection valve 1 is particularly suitable for injecting fuel directly into a combustion chamber (not shown) of an internal combustion engine.

The fuel injection valve 1 comprises a nozzle body 2, in which a valve needle 3 is arranged. The valve needle 3 stands with a valve closing body 4 in

30 operative connection, which cooperates with a valve seat surface 6 arranged on a valve seat body 5 to form a sealing seat. In the exemplary embodiment, the fuel injection valve 1 is an electromagnetically actuated fuel injection valve 1, which has a 5 spray opening 7. The nozzle body 2 is sealed by a seal 8 against the outer pole of a solenoid 10). The solenoid 10 is a coil housing 11 - - ^{1 -lj} - ³ - * ι τp _-___ -i ^■ _-______ ^■ _-. umii _ = τ-ιt- Sπo i crewi clr _! - t- el rather Inner pole 13 and outer pole 9 are separated from one another by a gap 26 and are supported on a connecting component 29. The magnet coil 10 is excited via a line 19 by an electrical current that can be supplied via an electrical plug contact 17. The plug contact 17 is surrounded by a plastic sheath 18, which may be molded onto the inner pole 13.

The valve needle 3 is guided in a disk-shaped valve needle guide 14. This is one

Paired shim 15, which for setting the

Valve needle stroke serves. On the upstream side of the

Adjustment disc 15 is an anchor 20. This is non-positively connected to the valve needle 3 via a flange 21, which is connected to the valve needle by a weld 22

Flange 21 is connected. On the flange 21, a return spring 23 is supported, which in the present

Design of the fuel injector 1 by one in the

Inner pole 13 pressed sleeve 24 is brought to bias.

Fuel channels 30a, 30b run in the valve needle guide 14 and in the armature 20. A filter element 25 is arranged in a central fuel feed 16. 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 against the stroke direction via the flange 21 on the valve needle 3 in such a way that the valve closing body 4 is held in sealing contact with the valve seat surface 6. When the magnetic coil 10 is excited, it 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 which is in the rest position between the inner pole 13 and the armature 20. The Stroke direction with. The valve closing body 4, which is in operative connection with the valve needle 3, lifts off the valve seat surface 6, and the fuel reaching the spray opening 7 i via swirl channels 36 and a subsequent annular gap 37 is sprayed off.

If the coil current is switched off, the armature 20 drops from the inner pole 13 after the magnetic field has been sufficiently reduced by the pressure of the return spring 23 on the flange 21, 3 whereby the valve needle 3 moves against the stroke direction. As a result, the valve closing body 4 is seated on the valve seat surface 6 and the fuel injector 1 is closed.

5 FIG. 2 shows an excerpted sectional view of the swirl-generating assembly of a fuel injector 1 according to the invention. The swirl-generating assembly consists of the valve seat body 5, the valve needle 3 and the one that is operatively connected to the valve needle 3

: 0 valve closing body 4.

On its upstream side 33, the valve seat body 5 has a guide recess 38 which serves to guide the valve needle 3 in the axial direction.

! 5 Downstream there is a preferably conical taper on which the valve seat surface 6 is arranged. The spray opening 7 connects downstream of the taper. On the upstream side 33 of the valve seat body 5 are swirl channels 36 in the

30 valve seat body 5 introduced. They are open to the upstream surface 33 of the valve seat body 5 and preferably open tangentially into the guide hole 38. The swirl channels are designed as grooves in the valve seat body 5. The bottom 39 of the grooves forms the 5 downstream boundary surface of the swirl channels 36 and is preferably arranged on a conical jacket, the opening angle α of which is identical to the opening angle β

- - ^{■ • •} -. ^> ι ^■ , ___ .. ι _ ._- „j t. ___], _ .. "Λr '-t- ^ η -, _-, V, e _____," 3 c; The valve needle 3 has a radial enlargement 31 upstream of the upstream surface 33 of the valve seat body 5, so that the upstream open swirl channels 36 are at least partially covered in the radial direction. Depending on the radial extent of the radial extension 31 and on the distance between the downstream surface 32 of the radial extension 31 and the upstream surface 33 of the valve seat body 5, the axial flow fraction of the fuel can thus be varied when the fuel injection valve 1 is open. The extent of the radial enlargement 31 is smaller than the inside diameter of the nozzle body 2. The changes in the axial component of the fuel flow during the opening and closing of the fuel injection valve 1 can, for. B. can be influenced by a conical or funnel-shaped design of the upstream surface 33 of the valve seat body 5. An influence by the corresponding surface 32 of the radial extension 31 is also possible.

»0

The valve closing body 4 connected to the valve needle 3 has a radial extent which is smaller than the guide recess 38 of the valve seat body 5. The cross-sectional area of the thus between

25 the valve closing body 4 and the valve seat body 5 formed annular gap 37 determines the metering of the fuel to be sprayed. The height of the annular gap 37 defined by the valve needle 3 is to be selected such that the 0 swirl channels 36 are connected to the annular gap 37 at least when the fuel injector 1 is open. If the valve needle 3 together with the valve closing body 4 is in its open end position when the magnet coil 10 is energized, the cross-sectional area of the annular gap 37 represents the smallest cross section 5 of the fuel flow to be flowed through on the way to the spray opening 7

'- * - - - ^• _ _ - j (-ι _τ _j_ 4-.-3 -, _ι - ~ n «1 1 nnr _f rl oo ή r _i he fuel injector according to the invention 1. The swirl channels 36 open tangentially into the annular gap 37, which is formed between the valve closing body 4 and the guide recess 38 of the valve seat body 5. The sum of the cross-sectional areas of the opening of the swirl channels 36 is larger than the cross-sectional area of the annular gap 37 formed between the guide recess 38 of the valve seat body 5 and the valve closing body 5. The cross-sectional areas of the openings can be adjusted by increasing the axial extent of the valve closing body 4 in the area of the annular gap 37.

Claims

Expectations

1. Fuel injector (1) for

Fuel injection systems of internal combustion engines with a valve needle (3) and a valve closing body (4) connected to the valve needle (3), which cooperates with a valve seat surface (6) arranged in a valve seat body (5) to form a sealing seat, and with at least one swirl-generating element, which is arranged upstream of the sealing seat in the valve seat body (5), characterized in that, as the swirl-generating element, one or more swirl channels (36) open to the upstream side (33) of the valve seat body (5) into the upstream side (33) of the valve seat body ( 5) are introduced.

2. Fuel injection valve according to claim 1, characterized in that the valve needle (3) upstream of the upstream side (33) of the valve seat body (5) has a radial extension (31).

3. Fuel injection valve according to claim 2, characterized in that the radial extension (31) on its s downstream

- - "'' ^Λ - - ¹ - -t - ^ -.-. F. ^^^ cr, qp.H tp> (T3) des

4. Fuel injection valve according to one of claims 1 to 3, characterized in that> the valve closing body (4) has a radial extent which is smaller than the radial extent of the valve needle (3).

5. Fuel injection valve according to one of claims 1 D to 4, characterized in that an annular gap (37) is formed downstream of the swirl channels (36) between the valve closing body (4) and a recess (40) of the Ventilsitzk body (5), 5 thereof Querschnit ^'tsflache forms the smallest of the fuel to flowing through cross-sectional area.

6. Fuel injection valve according to claim 5, characterized in that the annular gap (37) separates the sealing seat from the swirl channels (36).

7. Fuel injection valve according to one of claims 1 to 6, 5, characterized in that the swirl channels (36) in the Ventilsitzk body (5) introduced to the upstream side (33) are open grooves.

8. Fuel injection valve according to claim 7, characterized in that the bottoms (39) facing away from the upstream side (33) of the swirl channels (36) designed as grooves lie on a first conical surface (41). 5

9. Fuel injection valve according to claim 8,, -, characterized in that

"- ^{" •} ' ^■ "- ^I. ^JI - ^J _- ^, * ^U" I ^{, "} ι c TO _ΓΓC -T f1 surface (42) (41) with the opening angle (β) of the second conical surface (42) in each case with respect to a central axis (35) of the

Fuel injector (1) essentially coincides.