EP3384149A1

EP3384149A1 - Fuel injector having a control valve

Info

Publication number: EP3384149A1
Application number: EP16788726.4A
Authority: EP
Inventors: Lars Olems; Dominik WURST; Helmut Clauss; Oezguer Tuerker; Christian Faltin; Michael WALDENMAIER; Thomas Nierychlo; Fabian FISCHER
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2015-12-03
Filing date: 2016-11-02
Publication date: 2018-10-10
Anticipated expiration: 2036-11-02
Also published as: KR102623972B1; EP3384149B1; KR20180090842A; DE102015224177A1; CN108291509B; WO2017092955A1; CN108291509A

Abstract

The invention relates to a fuel injector (100) for injecting fuel into the combustion chamber of an internal combustion engine. The fuel injector (100) comprises a control valve (1) and an injection valve element (11). The injection valve element (11) bounds a control chamber (15) and is guided in the fuel injector (11) in such a way that the injection valve element can be moved longitudinally. The injection valve element (11) opens and blocks at least one injection opening (13) into the combustion chamber by means of the motion of the injection valve element. The control valve (1) controls the pressure in the control chamber (15). The control valve (1) comprises a magnet assembly (2), an armature (5), a valve piece (4), and a valve seat (7) formed on the valve piece (4). The armature (5) comprises an armature plate (50), which can be controlled by the magnet assembly (2). The armature (5) interacts at least indirectly with the valve seat (7) in order to relieve the control chamber (15). A crown ring (20) is clamped between the valve piece (4) and the magnet assembly (2).

Description

description

title

The invention relates to a fuel injector for injecting fuel into the fuel injector with control valve

Combustion chamber of an internal combustion engine, wherein the fuel injector a

Control valve has.

State of the art

Fuel injectors with control valves are widely known from the prior art, for example from the published patent application DE 196 50 865 A1. The known fuel injector for injecting fuel into the combustion chamber of an internal combustion engine comprises a control valve and an injection valve member. The injection valve member defines a control chamber and is longitudinally movably guided in the fuel injector. The injection valve member opens and blocks by its movement at least one injection opening in the combustion chamber. The control valve controls the pressure in the control room and includes a

Magnet assembly, an armature, a valve piece and a valve seat formed on the valve piece. An armature plate arranged on the armature can be actuated by the magnet assembly. The armature cooperates at least indirectly with the valve seat to relieve the control chamber.

The known Kraftstoffstoffinjektor has a comparatively complex Ankerhubeinstellung. The anchor stroke is the way between

Closed position and maximum open position, so the axial distance between the valve seat and the magnet assembly reduced by the interposed components of the armature including an optional

Closing body. This leads to a series production during the assembly of the fuel injector to tolerance-related high variations of the armature stroke. On the other hand, it comes during operation due to

Temperature loads to thermal expansions, which result in a change of the armature stroke with the temperature. The function of the whole

As a result, the fuel injection valve is no longer robust above the operating temperature.

Disclosure of the invention

In contrast, the armature stroke of the fuel injector according to the invention over the operating temperature is almost constant. Furthermore, at the

Ankerhubeinstellung comparatively little components involved, so that the tolerance error of the armature stroke is minimized during assembly. The

Functionality of the entire fuel! njektors is thus improved and made more robust.

For this purpose, the fuel injector comprises a control valve and an injection valve member. The injection valve member defines a control chamber and is longitudinally movable in the fuel! guided by a projector. The injection valve member opens and blocks by its movement at least one injection opening in the combustion chamber. The control valve controls the pressure in the control room. The control valve comprises a magnet assembly, an armature, a valve piece and an on the

Valve piece formed valve seat. The armature comprises an armature plate, wherein the armature plate can be controlled by the magnet assembly. The armature cooperates at least indirectly with the valve seat to relieve the control chamber. A crown ring is between the valve piece and the

Magnetic assembly braced. The crown ring thus defines, optionally together with others

Components, the distance between the valve piece with the valve seat on the one hand and the magnet assembly on the other. The two fixed positions for the armature stroke are thus defined in a simple manner and

accordingly minimizes tolerance fluctuations. For the change of the armature stroke above the operating temperatures so only the Thermal expansion coefficients of anchor and crown ring are taken into account.

In an advantageous development, a cylindrical lateral surface is formed on the valve piece. The crown ring is positioned coaxially with the valve seat on this lateral surface. Due to the coaxiality of the crown ring is optimally aligned to the valve piece and the valve seat, accordingly, the power flow is very homogeneous, so there is no tilting or

Slanted positions of the strained components comes. The rotational symmetry can be obtained as far as possible.

In an advantageous development, a cylindrical guide surface is formed on the crown ring. The anchor is longitudinally movable in this

Guided guide surface. As a result, the crown ring has a further function: it aligns the armature radially or positions it coaxially with the valve seat. Thus, the closing function of the control valve and its life are optimized; there are no malfunctions or inconsistencies of the control valve. An oblique position of the anchor usually means increased wear of the

Control valve.

In advantageous embodiments, a Ankerhubeinstellscheibe is clamped between the crown ring and the valve piece. The Ankerhubeinstellscheibe is easier to manufacture than the crown ring. Therefore, the Ankerhubeinstellscheibe can also be made easier with different disc thicknesses, which then depending on the tolerance chain of the components involved for setting the

Ankerhubs be built specifically. The crown ring can therefore

cost-effectively manufactured in only one height. In an alternative embodiment, the Ankerhubeinstellscheibe is clamped between the crown ring and the magnet assembly.

In an advantageous development of the crown ring surrounds the anchor outside. As a result, the crown ring encompasses the anchor virtually. The anchor can thus remain geometrically unchanged; the electromagnetic force acting on the armature or armature plate is thus not influenced by the crown ring. In an advantageous alternative embodiment is in the anchor plate a

Plate groove formed. The crown ring has a crown with the crown protruding through the plate groove. As a result, the control valve - especially in the armature and crown ring - designed very space-saving. A reprecipitation of the anchor is not required. Preferably, the crown ring also fulfills the

Function of an anti-rotation, that is, a rotation of the armature plate or the armature about its longitudinal axis is prevented.

In an advantageous development, a bearing recess is formed in the crown. In the bearing recess a rolling element is mounted, wherein the

Rolling element cooperates with the plate groove. Preferably, the rolling element is designed spherical. The armature plate or the armature thus rolls off during the opening and closing of the control valve on the rolling elements. The occurring friction is minimal due to the theoretical point support and constant over the service life. The anti-rotation is thus very low friction and energy-saving.

Advantageously, the rolling element is made of an amagnetic material, preferably a ceramic. As a result, the rolling element is not subject to the magnetic assembly caused by the electromagnetic

Forces.

In advantageous embodiments, a residual air gap disk is arranged between the magnet assembly and the anchor plate. As a result, a so-called bonding between the armature plate and the magnet assembly in maximum

Opening position, ie at maximum armature stroke, avoided. Preferably, the residual air gap disc is not magnetic.

In advantageous embodiments, the material of the crown ring has a greater coefficient of thermal expansion than the material of the anchor. Preferably, the crown ring is arranged at least partially surrounding the armature radially.

The armature is consequently subject to a greater temperature load during operation due to the rapidly flowing and high pressure fuel.

Due to the larger coefficient of thermal expansion of the crown ring with respect to the length changes occurring, the different Temperature loads compensated. The occurring in the control valve thermal stresses are minimized.

Advantageously, the material of the crown ring is non-magnetic. Preferably, the crown ring is made of an austenitic sintered steel or a ceramic. As a result, the crown ring influences the magnetic field of the

Magnetic assembly not negative. The magnetic force on the anchor plate is thus not distorted.

In advantageous embodiments, the magnet assembly is clamped by means of a tension spring with the crown ring. This is a very simple and efficient bracing. On additional elaborate screw in the interior of the fuel injector can be dispensed with.

In advantageous developments, the magnet assembly of at least one contact pin is electrically contacted. Furthermore, the at least one

Contact pin on a slider seat. As a result, the magnet assembly can be axially variably positioned in the assembly, without the electrical

Contact is lost.

In advantageous embodiments, the armature is acted upon by a spring in the direction of the valve seat. This is on the one hand a simple and inexpensive design to press the armature or the closing body against the valve seat in the closed position. On the other hand, the closing of the control valve is so very fast and efficient.

In advantageous developments, an anchor bolt protrudes through the anchor. Thereby, the hydraulically resulting force can be reduced to the armature in the axial direction or even set to zero. Thus, a pressure or

force balanced control valve can be realized. Accordingly, for example, the magnetic assembly and the spring can be made smaller, since only smaller forces are required to move the armature.

Preferably, the anchor bolt and the valve seat have almost the same diameter. As a result, a pressure or force balanced control valve is realized. Brief description of the drawings

With reference to the drawing, the invention will be discussed in more detail below

described.

It shows:

1 shows a schematic representation of a fuel injector from the prior art,

FIG. 2 shows a longitudinal section of a control valve according to the invention, only the essential areas being shown,

Figure 3 shows the section A-A of Figure 2 by the control valve of

fuel injector,

4 shows a control valve according to the invention in longitudinal section in a further embodiment, wherein only the essential areas are shown,

5 shows a control valve according to the invention in a longitudinal section in yet another embodiment, wherein only the essential areas are shown,

6 shows a control valve according to the invention in a longitudinal section in yet another embodiment, wherein only the essential areas are shown,

7a shows a control valve according to the invention in a perspective view with a cut anchor in yet another embodiment, wherein only the essential areas are shown, FIG.

Figure 7b is the plan view of the embodiment of Figure 7a, wherein only the essential areas are shown. 8a shows a control valve according to the invention in section in yet another embodiment, wherein only the essential areas are shown,

8b shows the plan view of the embodiment of Figure 8a, wherein only the essential areas are shown.

description

1 is a schematic view of a fuel injector 100, as known from the prior art. With the fuel! Injector 100, fuel is injected into the combustion chamber of an internal combustion engine. Of the

Fuel! The injector 100 comprises a holding body 10 and a control valve 1 with a magnet assembly 2 and a magnetic core 3 arranged therein. The control valve 1 accommodates a movably received in the holding body 10

Injection valve member 1 1 operable.

The injection valve member 1 1 - formed in a generally needle-shaped - gives at a combustion chamber end of the fuel injector 100 at a

Nozzle body 12 formed injection openings 13 in the combustion chamber of the internal combustion engine free or closes them, so that fuel can be injected if necessary into the combustion chamber. The nozzle body 12 is screwed by a clamping nut 14 with the holding body 10 media-tight.

The control valve 1 comprises a valve piece 4, which is installed in the holding body 10 and has a control chamber 15 for actuating the injection valve member 1 1, whose opening or closing is controlled by the control valve 1. The operation of the fuel injector 100 is such that at a pressure reduction in the control chamber 15, the injection valve member 1 1 in the

Control chamber 15 pushes and thus the injection ports 13 is free and that at a pressure increase in the control chamber 15 of this hydraulic pressure the

Injection valve member 1 1 presses in the direction of the combustion chamber and thereby the injection openings 13 are closed.

In general, the injection valve member 1 1 can also be designed in several parts. 2 shows a control valve 1 according to the invention in longitudinal section, wherein only the essential areas are shown. At the bottom of Figure 2 is still guided in the valve member 4 injection valve member 1 1 can be seen, which is moved by the pressure change in the control chamber 15 in the axial direction of the fuel injector 100. The valve piece 4 is clamped in the holding body 10. The control chamber 15 is connected by a formed in the valve piece 4 outlet throttle 16 with a valve chamber 17. The valve chamber 17 is connected by the control valve 1 with a low-pressure chamber 18, wherein the low-pressure chamber 18 opens into an unillustrated return system of the fuel injector 100.

The valve chamber 17 is bounded by the valve piece 4, an at least partially tubular anchor 5 and an anchor bolt 6. Of the

Low-pressure space 18 is bounded by the valve piece 4 and the armature 5. The armature 5 cooperates with a valve seat 4 formed on the valve seat 7. If the armature 5 abuts on the valve seat 7, then a hydraulic connection is separated from the valve chamber 17 to the low-pressure chamber 18; if the armature 5 is lifted off the valve seat 7, then the hydraulic connection from the valve chamber 17 to the low-pressure chamber 18 is opened.

The anchor bolt 6 is at least partially disposed in a bore of the armature 5 and thus guides the armature 5 longitudinally movable. The anchor bolt 6 further limits the valve space 17 and thus serves to equalize the pressure of the armature 5. Consequently, the armature 5 is sleeve-shaped at least in its region adjacent to the valve space 17 and can thus be pressure- or

be designed force balanced by the valve seat 7 has almost the same diameter as the anchor bolt 6. Strictly speaking, the bore of the armature 5, through which the anchor bolt 6 projects, the same

Diameter as the valve seat 7. Then the hydraulic

resulting force on the armature 5 in the axial direction equal to zero. The

Control valve 1 is then referred to as force-balanced or pressure-balanced.

The longitudinal movement of the armature 5 may alternatively also by a

Ventilstückhals 41 of the valve member 4 are guided. The armature 5 is acted upon by a spring 8 and is pressed by this against the valve seat 7. Optionally, a bearing ring 81 is arranged between the armature 5 and the spring 8, wherein the bearing ring 81 preferably serves to adjust the force of the spring 8. The magnet assembly 2 with the magnetic core 3 disposed therein is at the valve space 17

arranged opposite side of the armature 5 and optionally surrounded by a magnetic sleeve, not shown. When the magnet core 3 is energized by contact pins 31, an electromagnetic force is exerted on an armature plate 50 of the armature 5, so that the armature 5 is lifted off the valve seat 7 against the force of the spring 8.

The magnet assembly 2 is supported by a crown ring 20 and a

Ankerhubeinstellscheibe 21 directly on the valve piece 4 from. For this purpose, an end face 40 is formed on the valve piece 4, which cooperates with the Ankerhubeinstellscheibe 21. The crown ring 20 is subsequently connected to the

Magnet assembly 2 braced, with at least one crown 29 on the

Crown ring 20 is formed or arranged. The anchor plate 50 has at least one plate groove 54, through which the crown 29 is guided in the axial direction. The crown 29 cooperates with the magnet assembly 2 or is clamped with this.

The magnet assembly 2 in turn is pressed by a tension spring 22 against the crown 29. The tension spring 22 may, as shown in Figure 2, be designed as a plate spring, alternatively with opposite curvature. However, the tension spring 22 may also be designed as any spring, for example as a wave spring.

A locking ring 24 serves as an assembly aid, so that the magnet assembly 2 does not fall out of the fuel injector 100 during assembly. A

Restluftspaltscheibe 23 is disposed externally between the magnet assembly 2 and the armature 5 and prevents adhesion of the armature 5 at the

Magnet assembly 2. Alternatively, the residual air gap disc 23 may also be designed on the inside; then it would be located between the inner pole of the magnet assembly 2 and the anchor plate 50. To adjust the armature stroke, so the way the armature 5 in its opening and closing movements between the valve seat 7 and the

Restluftspaltscheibe 23 can perform, the relevant dimensions of the control valve 1 adapted a corresponding Ankerhubeinstellscheibe 21 is used. In alternative embodiments, the crown ring 20 and the Ankerhubeinstellscheibe 21 may also be made in one piece; Accordingly, the armature stroke would then be adjusted over the axial length of the crown ring 20.

The crown ring 20 can advantageously be designed as an austenitic sintered part so as not to impair the magnetic flux of the magnetic assembly 2. Alternatively, a ceramic sintered part can be used.

3 shows the section A-A of Figure 2 by the control valve. 1 The armature 5 is longitudinally movable on the anchor bolt 6, that is perpendicular to the cutting plane, out. The armature plate 50 of the armature 5 has three armature wings 51, 52, 53, each having a circular segment shape. Between each two armature blades, a respective plate groove 54, 55, 56 of the anchor plate 50 is formed. In each case a crown 29 of the crown ring 20 is arranged in each case a plate groove 54, 55, 56, so that the three crowns 29 protrude through the anchor plate 50 and contact the magnet assembly 2 in the mounted state. In alternative embodiments, the crown ring 20 may have any number of crowns 29.

The crowns 29 are used in an advantageous development not only the

Tensioning or positioning of the magnet assembly 2, but also as a rotation of the anchor plate 50 and the armature 5. Unnecessary rotation of the armature 5 and thus also additional wear are avoided.

4 shows a further embodiment of the invention

Control valve 1 in longitudinal section, which will be discussed below only the essential differences from the embodiment of Figure 2.

In the embodiment of Figure 2, the armature 5 is guided by the anchor bolt 6, or alternatively by the valve neck 41, longitudinally movable. The leadership of the armature 5 is carried out in the embodiment of Figure 4 by the crown ring 20. For this purpose, a collar 42 is disposed on the valve member 4, which inside the Valve space 17 limited. On an outer circumferential surface 43 of the collar 42, the crown ring 20 is fixed at least radially by means of an inner positioning surface 27 formed on it, so that it is preferably arranged concentrically to the valve seat 7. In alternative embodiments, however, the positioning surface 27 can also be located on the outside and thus the lateral surface 43 on the inside. The collar 42 is made shorter in comparison to the valve neck neck 41 of Figure 2, since it no longer has a guide function for the armature 5.

The crown ring 20 is arranged at least partially surrounding the armature 5 radially. The crown ring 20 further has an inner guide surface 28, with which the armature 5 is longitudinally movably guided. In advantageous embodiments, the positioning surface 27 and the guide surface 28 are the same inner

Lateral surface of the crown ring 20, wherein the positioning surface 27 and the

Guide surface 28 viewed in the axial direction are arranged one above the other.

Furthermore, in the crown ring 20 at least one Abiaufbohrung 26th

formed, which is part of the low-pressure chamber 18 and thus connects the valve chamber 17 with the low-pressure system or return system of the fuel injector 100. The contact pins 31 in the embodiment of Figure 4 have a slide seat 31 a, through which the axial length of the contact pin 31 is made variable, so that the magnet assembly 2 during the

Mounting process can be positioned axially correctly without the electrical contact of the magnetic core 3 is interrupted.

Even in the embodiment shown in Figure 4, the crown ring 20 and the Ankerhubeinstellscheibe 21 can be made in one piece.

5 shows yet a further embodiment of the control valve 1 according to the invention in longitudinal section, wherein only the essential differences from the exemplary embodiments of FIGS. 2 and 4 will be discussed below.

Also, in the embodiment of Figure 5, the guide of the armature 5 takes place through the crown ring 20 and through the guide surface 28 of the crown ring 20. For this purpose, analogous to the embodiment of Figure 4, the positioning surface 27 of the crown ring 20th fixed at least radially on the collar 42 of the valve member 4 or arranged with very little clearance.

In the embodiment of Figure 5, however, the crown 29 is not passed through a plate groove of the anchor plate 50, but surrounds or embraces the

Anchor plate 50 outside. As a result, the anchor plate 50 can be made without grooves as a complete circular ring. However, the radial extent of the crown 29 is optionally increased. In the crown 29 and in the crown ring 20 Abströmlöcher 25 are formed, which are part of the low-pressure chamber 18. Optionally, the outflow holes 25 can also be dispensed with if the flow gaps on the outside of the crown ring 20 or the crown 29 have a sufficient flow cross section.

The Ankerhubeinstellscheibe 21 is between the crown 29 and the

Magnet assembly 2 braced. In all embodiments, the

Ankerhubeinstellscheibe 21, however, either be clamped between the crown 29 and the magnet assembly 2, or between the crown ring 20 and the valve member 4, or be made integral with the valve member 4. In the embodiment of Figure 5, the residual air gap disc 23 is further arranged at the inner pole of the magnet assembly 2 between this and the armature plate 50, wherein the radial positioning of the residual air gap disc 23 for all

Embodiments are freely selectable.

The fuel injector 100 of the embodiment of Figure 5 further comprises a spring adjusting disc 80, which serves to adjust the tension spring 22.

For this purpose, the holding body 10 is screwed with the interposition of the spring adjusting disc 80 by a union nut 9a with a holding body head 9. On the holding body head 9, a stop surface 9b is formed, at which

Preferably, both the spring 8 and the tension spring 22 and the

Support anchor bolts 6.

The fact that the valve member 4 is fixed to the holding body 10 is about valve piece 4, holding body 10, spring adjusting disk 80 and 9 holding body head the

Stop surface 9b positioned. On the other hand, via the valve piece 4, the crown ring 20 and the Ankerhubeinstellscheibe 21, a lower stop for the

Magnet assembly 2 defined. An upper distance between the Magnet assembly 2 and the abutment surface 9b is now through the

Federeinstellscheibe 80 set so that thereby also the force of

Tension spring 80 is adjusted. Furthermore, the force of the spring 8 is adjusted by means of the support ring 81. Thus, when energized magnetic core 3, so when planting the armature 5 to the valve seat 7, between the armature 5 - or the support ring 81 - and the stop surface 9b strained spring 8 in terms of their spring force and their travel very well by the height of Auflagerings 81 are set.

6 shows a section of a further embodiment of the control valve 1 according to the invention in longitudinal section. In contrast to the preceding exemplary embodiments, the embodiment of FIG. 6 has a spherical closing body 60 which is positioned in a receiving piece 61. The receiving piece 61 is arranged between the armature 5 and the closing body 60 and is acted upon by the armature 5, wherein the

Guide surface 28 of the crown ring 20, the armature 5 longitudinally movable leads.

Due to the spherical closing body 60, the control valve 1 is no longer force-balanced in this embodiment.

The components anchor 5, receiving piece 61 and closing body 60 can be carried out in one or two parts in alternative embodiments.

The crown ring 20 is clamped between a formed on the valve piece 4 paragraph 49 and the magnet assembly 2, optionally with the interposition of Ankerhubeinstellscheibe 21. Here, the lateral surface 43 of the valve member 4 is located inside and the positioning 27 of the crown ring 20 outboard. The crown ring 20 is thus positioned coaxially with the valve piece 4 and consequently coaxially with the valve seat 7. Analogous to the

previous examples but the lateral surface 43 also

outboard and the positioning surface 27 to be executed inside.

In the illustration of Figure 6, only the essential areas are shown; However, it is understood that the holding body head 9 is at least indirectly connected to the valve piece 4, so that a tension of the

Crown ring 20 can be done. The crown ring 20 has in this embodiment, two crowns 29, which protrude through two plate grooves 54, 55 of the anchor plate 5. Alternatively, however, any number of crowns 29 and plate grooves 54, 55, 56 may be used.

Furthermore, the crown ring 20 can also be designed to surround the armature 5 on the outside, as shown in FIG.

7 shows a further embodiment of the control valve 1, wherein only the essential areas are shown. FIG. 7 a shows the control valve 1 in a perspective view with a cut anchor 5 and FIG. 7 b shows the control valve 1 in plan view of the anchor plate 50.

The crown ring 20 of the embodiment of FIG. 7a / FIG. 7b advantageously has three crowns 29, it being possible in principle for any number of crowns 29 to be used. The anchor plate 50 has a corresponding number of plate grooves 54, 55, 56, through which the crowns 29 are passed in the axial direction. The crowns 29 cooperate with the front side of the magnetic assembly 2, not shown, or are clamped with this.

In the embodiment of Figure 7 are in the crowns 29 each one

Bearing recess 59 is formed. The bearing recesses 59 are

designed in such a way that they are open in the circumferential direction of the crown ring 20 and the magnet assembly 2. The

Bearing recesses 59 serve to receive rolling elements 58, which are preferably spherical in shape; thereby fulfill the

Bearing recesses 59 the function of bearing cages. The rolling elements 58 are dimensioned and positioned in the bearing recesses 59, that they cooperate with the plate grooves 54, 55, 56 of the anchor plate 50, in both circumferential directions, ie tangentially, so that each rolling element 58th

Can transmit rotational forces in both directions. The armature 5 is therefore guided by the rolling elements 58 almost smoothly.

The rotation of the armature plate 50 and the armature 5 is thus very low friction and low-wear, because the armature 5 rolls almost over its plate grooves 54, 55, 56 on the rolling elements 58. Preferably, the rolling elements 58 are made of a non-magnetic material, such as a ceramic, so that they are not affected by the

electromagnetic forces of the magnet assembly 2 are affected. FIG. 8 shows an anti-rotation lock of the anchor plate 50 that is alternative to FIG.

FIG. 8a shows the control valve 1 in a longitudinal section in the region of a roller body 58 and FIG. 8b shows the control valve 1 in plan view of the anchor plate 50. The bearing recesses 59 are cup-shaped in the embodiment of FIG. 8, with one in each case Circumferential direction of the armature 5 open end. A rolling element 58 is positioned in each case in a bearing recess 59 so that it at the open end of the bearing recess 59 with a flank of the

corresponding plate groove 54, 55, 56 cooperates. This will be the

Anchor plate 50 mounted on a plate groove 54, 55, 56 in a circumferential direction, but not in the opposite direction oriented circumferential direction. Therefore, at least one further rolling element 58 is required, which also supports the armature plate 50 in the oppositely oriented circumferential direction. In the embodiments of Figure 8 are thus at least two crowns 29, each with a rolling body 58 disposed therein required to a

ensure friction-minimized anti-twist protection. In this case, unlike in FIGS. 8a / 8b, the crown ring preferably has an even number of crowns 29, so that the rolling elements 58 arranged in the associated bearing recesses 59 guide the anchor plate 50 in pairs in both

Store circumferential directions.

The rolling elements 58 are mounted in the radial direction of the crowns 29. Alternatively, the radial direction to the outside can also be supported by a further component, for example by the residual air gap disk 23, if this is arranged as in the exemplary embodiment of FIG.

The operation of the fuel injector 100 according to the invention is as follows: The injections via the injection openings 13 into the combustion chamber of

Internal combustion engine by the longitudinal movement of the on or multipart injection valve member 1 1 executed, the longitudinal movements are in turn controlled by the control valve 1, wherein the control valve 1 is driven by the magnet assembly 2. The injection valve member 1 1 is longitudinally movably guided in the valve piece 4 at its end opposite the injection openings 13 and defines the control space 15 there.

When the magnet core 3 is energized, the magnet assembly 2 exerts an attractive force on the armature 5 and moves it away from the valve seat 7 against the force of the spring 8. The hydraulic connection from the valve chamber 17 to the low pressure chamber 18 is thereby opened and the control chamber 15 is consequently relieved. The hydraulically closing force in the control chamber 15 on the injection valve member 1 1 in the direction of the injection openings 13 decreases and the injection valve member 1 1 releases the injection openings 13, so that the fuel injector 100 injects into the combustion chamber of the internal combustion engine.

To end the injection process, the energization of the magnetic core 3 is released, so that the armature 5 is pressed by the spring 8 against the valve seat 7. The hydraulic connection from the valve chamber 17 to

Low-pressure chamber 18 is thereby closed and the control chamber 15 is filled with fuel under high pressure via an inlet throttle, not shown. As a result, the hydraulically closing force in the control chamber 15 increases on the injection valve member 1 1 in the direction of the injection openings 13 again and the injection valve member 1 1 closes the injection openings 13th

According to the invention, the components of the control valve 1 which have an influence on the stroke of the armature 5 are reduced: the axial distance between the valve seat 7 and the magnet assembly 2 is defined by valve piece 4, crown ring 20 and, if appropriate, armature stroke adjusting disk 21. Subtracting from the effective length of the armature 5 and possibly the height of the

Restluftspaltscheibe 23, we obtain the maximum possible armature stroke. By reducing the components involved in the armature stroke, the pressure and temperature dependence of the armature stroke are reduced; the two components determining the axial length are the armature 5 and the crown ring 20. In the case of the valve seat 7 flowing out of the control chamber 15, the lower part is located underneath

High-pressure fuel, the armature 5 heats up dynamically faster As a result, the material of the

Crown ring 20 chosen so that there is a larger

Thermal expansion coefficient has as the material of the armature 5. As a result, the Ankerhubverlust caused by the different temperature gradients at the armature 5 and the crown ring 20, through the

Thermal expansion coefficient of the crown ring 20 can be compensated.

Advantageously, the material of the crown ring 20 is further selected so that it does not affect the magnetic flux of the magnet assembly 2, for example austenitic steel or a ceramic.

In advantageous developments, the protruding through the anchor plate 50 through crowns 29 of the crown ring 20 also have a function for

Anti-rotation of the anchor plate 50 and the armature 5. By using rolling elements 58, this rotation can be made particularly low friction.

Claims

claims

1 . Fuel injector (100) for injecting fuel into the combustion chamber

an internal combustion engine, the fuel! injector (100) a control valve

(1) and an injection valve member (1 1), wherein the injection valve member (1 1) defines a control chamber (15) and longitudinally movable in the

Fuel injector (1 1) is guided and opens by its movement at least one injection port (13) into the combustion chamber and blocks, wherein the

Control valve (1) controls the pressure in the control chamber (15), wherein the control valve (1) comprises a magnet assembly (2), an armature (5), a valve piece (4) and a valve seat (7) formed on the valve piece (4) wherein the armature (5) comprises an armature plate (50), wherein the armature plate (50) of the magnet assembly (2) is controllable, wherein the armature (5) at least indirectly with the valve seat (7) for relieving the control chamber (15 ) cooperates,

characterized in that

a crown ring (20) between the valve piece (4) and the magnet assembly

(2) is tense.

2. Fuel! The injector (100) according to claim 1, characterized in that a cylindrical jacket surface (43) is formed on the valve piece (4), the crown ring (20) being positioned coaxially with the valve seat (7) on the jacket surface (43).

3. Fuel! A njector (100) according to claim 1 or 2, characterized in that on the crown ring (20) has a cylindrical guide surface (28) is formed, wherein the armature (5) is longitudinally movably guided in the guide surface (28).

4. Fuel! A njector (100) according to any one of claims 1 to 3, characterized

in that an armature stroke adjusting disc (21) is clamped between the crown ring (20) and the valve piece (4).

5. fuel injector (100) according to one of claims 1 to 3, characterized in that a Ankerhubeinstellscheibe (21) between the crown ring (20) and the magnet assembly (2) is braced.

6. Fuel! A njektor (100) according to any one of claims 1 to 5, characterized

in that the crown ring (20) surrounds the armature (5) on the outside.

7. Fuel! A njektor (100) according to any one of claims 1 to 5, characterized

characterized in that in the anchor plate (50) a plate groove (54) is formed and in that the crown ring (20) has a crown (29), wherein the crown (29) protrudes through the plate groove (54).

8. Fuel injector (100) according to claim 7, characterized in that in the crown (29) has a bearing recess (59) is formed, wherein in the bearing recess (59) a rolling body (58) is mounted, wherein the

Rolling element (58) cooperates with the plate groove (54).

9. Fuel! A njector (100) according to any one of claims 1 to 8, characterized

characterized in that between the magnet assembly (2) and the

Anchor plate (50) a residual air gap disc (23) is arranged.

10. Fuel! A njector (100) according to any one of claims 1 to 9, characterized

in that the material of the crown ring (29) has a greater thermal expansion coefficient than the material of the armature (5).

1 1. Fuel injector (100) according to one of claims 1 to 10, characterized

in that the material of the crown ring (29) is nonmagnetic, preferably an austenitic sintered steel or a ceramic.

12. Fuel injector (100) according to any one of claims 1 to 1 1, characterized

characterized in that the magnet assembly (2) by means of a tension spring (22) is clamped to the crown ring (20).

13. Fuel injector (100) according to any one of claims 1 to 12, characterized

in that the magnet assembly (2) of at least one Contact pin (31) is electrically contacted and that the at least one contact pin (31) has a slide seat (31 a).

14. Fuel injector (100) according to one of claims 1 to 13, characterized in that the armature (5) by a spring (8) in the direction of

Valve seat (7) is acted upon.

15. Fuel! Njector (100) according to one of claims 1 to 14, characterized in that an anchor bolt (6) protrudes through the armature (5).