EP2307697A1

EP2307697A1 - Fuel injector with two-piece armature

Info

Publication number: EP2307697A1
Application number: EP09769057A
Authority: EP
Inventors: Andreas Rettich
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2008-06-27
Filing date: 2009-04-27
Publication date: 2011-04-13
Anticipated expiration: 2029-04-27
Also published as: EP2307697B1; WO2009156208A1; DE102008002717A1; RU2011102820A; RU2517518C2; CN102076950A

Abstract

The invention relates to a fuel injector (110) for injecting fuel into the combustion chamber of an internal combustion engine, especially for use in accumulator injection systems. The fuel injector (110) comprises at least one injection valve member (116) for closing or releasing at least one injection opening, said injection valve member being movably supported in an injector body (114) of the fuel injector (110). The fuel injector (110) also comprises at least one hydraulic valve (146), wherein the hydraulic valve (146) is provided to control a stroke of the injection valve member (116) via at least one control chamber (124). The hydraulic valve (146) comprises a magnetic actuator (148) having at least one magnetic coil (150) and at least one armature (154). The armature (154) comprises at least one armature plate (162), which interacts with the magnetic actuator (148), and at least one armature bolt (164), which is supported so as to be movable relative to the armature plate (162) and which controls a pressure in the control chamber (124).

Description

June 19, 2008

description

title

Fuel injector with two-part magnet armature

State of the art

For supplying combustion chambers of internal combustion engines, in particular self-igniting internal combustion engines, with fuel, both pressure-controlled and stroke-controlled injection systems can be used. As fuel injection systems, so-called accumulator injection systems are used in the pump-nozzle units, pump-line-nozzle units. In common rail systems, high pressure fuel (eg, fuel at over 1000 bar) is provided by a high pressure accumulator to a fuel injector. Common rail injectors make it possible in an advantageous manner to adapt the injection pressure to the load and the speed of the internal combustion engine. The following invention relates in particular to common rail fuel injectors, but in principle can also be used for other types of fuel injectors.

In conventional common rail injectors, an actuator is generally used for opening the fuel injector, that is to say for starting the injection process, and for subsequently closing the fuel injector. For example, magnetic actuators or piezoactuators can be used here, the invention described below starting from the use of magnetic actuators.

In such fuel injectors with hydraulic valves with magnetic actuators in particular a pressure balance of the hydraulic valves is desired. This means that the closing force of the hydraulic valves, ie the force by means of which the hydraulic valves seal a pressure in a control chamber of the fuel injector, is independent of the system or rail pressure. This is achieved by the fact that the sealing effect of the hydraulic valves does not have to be applied against the applied pressure. For smaller strokes can thus be used in particular large valve cross sections. With such pressure balanced solenoid valves, significant improvements in multiple injection can be achieved. In particular, the very small solenoid valve strokes, which may be smaller, for example, by about 50% than, for example, the strokes of fuel injectors with comparable ball valves, increase the stability of fuel injectors with pressure balanced hydraulic solenoid valves significantly.

A problem with such fuel injectors, however, is the bouncing of the solenoid valve anchor when closing the valve. Due to this bounce, the minimum time interval between switching operations is typically limited to 200 to 250 μs. This is due in particular to the fact that even slight changes in the bounce behavior over the runtime can lead to a significant injection quantity drift if the armature closing bounce is not completed when a follow-up injection, for example the second injection, is triggered. In many cases, however, spray intervals, ie distances between individual switching operations of the hydraulic valve, of about 100 microseconds are required.

Disclosure of the invention

It is therefore proposed a fuel injector for injecting fuel into the combustion chamber of an internal combustion engine, which at least largely avoids the disadvantages of known fuel injectors described above. The fuel injector can be used in particular for use in accumulator injection systems, in particular in self-igniting internal combustion engines, although other uses are also conceivable. In particular, the described fuel injector can be considerably reduced by means of the proposed fuel injector, which can lead to spray intervals of less than 200 μs. At the same time, the advantages of pressure balanced hydraulic valves can be maintained.

A basic idea of the present invention is that armature closing bouncing can be prevented by decoupling the anchor bolt and the anchor plate. As a result, the advantages of a pressure balanced valve can be further optimized, and in particular very small temporal spray clearances can be realized. The invention can be combined with respect to the production, including assembly with fuel injectors with one-piece anchor, so that, for example, the fuel fϊnjektor invention with multi-part anchor can be offered as an option on customer request.

The manufacture of the armature is significantly simplified compared to conventional armature. In addition, the decoupling of the anchor bolt and the anchor plate separates makes material optimizations. Different materials can be used for the anchor bolt and the anchor plate. Thus, for example, the anchor plate with respect to the magnetic properties and the geometry can be optimally designed, as well as the separately formed anchor bolt can be optimized, for example, optimal closure properties and the lowest possible wear. In particular, no consideration must be given to wear on the valve seat with regard to the selection of materials and the geometric design of the anchor plate. For the anchor bolt, however, both material and geometry can be reduced for minimal wear and optimum sealing properties. Furthermore, eliminates the need for the use of a spring plate, since, for example, setting rings for an elevation can be used as a measure group.

The assembly of the proposed fuel injector can be carried out using an armature designed as an assembly. For example, as explained in more detail below, this assembly can comprise an anchor plate, an anchor sleeve, an adjusting ring, in particular a sickle disc. This assembly can be preassembled outside the actual assembly of the fuel injector, for example, and delivered as a ready-preassembled assembly to the assembly of the actual fuel injector.

In order to implement the inventive idea described above, the fuel injector comprises an injection valve member movably mounted in an injector body of the fuel injector for closing or releasing at least one injection opening. The injection valve member may be designed in one or more members.

Furthermore, the proposed fuel injector comprises at least one hydraulic valve, which is set up to control a stroke of the injection valve via at least one control chamber. In this case, as described above, the hydraulic valve can be designed as a pressure-balanced valve, that is, as a valve to which even in the closed state, no high pressure of the fuel, so for example, no rail pressure acts. This can be done, for example, in that the hydraulic valve does not provide any hydraulic surface acting on the fuel in an opening or closing direction of the hydraulic valve, for example, no surface or surface component aligned perpendicular to the opening of a drainage bore to be closed.

The hydraulic valve has at least one magnetic actuator with at least one magnetic coil and at least one magnet armature. The magnet armature in turn comprises at least one armature plate interacting with the magnet actuator and at least one movably mounted relative to the armature plate and controlling a pressure in the control chamber Anchor bolt on. This anchor bolt is preferably designed to release or close at least one outlet throttle of the control chamber, in accordance with the control of the magnetic actuator. An anchor bolt is thus to be understood as a fundamentally arbitrarily shaped closing element, which can be designed, for example, as an elongate closing element with an arbitrary cross-section, for example in the form of a solid bolt. Also, a hollow cross-section may be present, which is explained in more detail below using the example of a preferred sleeve shape.

The anchor bolt can be acted upon in particular by means of a valve spring element, for example a helical valve spring, with a force acting in a closing direction of the hydraulic valve first force. The armature plate in turn can be acted upon in particular by means of at least one armature spring element, for example a helical armature spring, with a second force acting counter to the closing direction. In this case, this second force is preferably lower than the first force.

The anchor bolt, for example, be stored within the anchor plate or the anchor plate surrounding, so that the anchor bolt and the anchor plate relative to each other in the closing direction are displaced. In this case, the anchor bolt is preferably mounted relative to the anchor plate such that a movement of the anchor plate in an opening direction against the closing direction, at least from a certain minimum stroke, entrains the anchor bolt, so that the hydraulic valve opens. This can be done for example via appropriate shoulders and / or other entrainment devices on the anchor bolt and / or on the anchor plate.

The anchor bolt may in particular be designed sleeve-shaped and thus comprise an anchor sleeve or be designed as an anchor sleeve. In this case, the anchor sleeve is preferably mounted in the axial direction sliding on the anchor plate, in particular within the anchor plate. The sleeve shape of the anchor bolt in the form of an anchor sleeve is particularly advantageous for the design of a pressure balanced hydraulic valve, measure the above definition, since an anchor sleeve can be used to provide as possible no hydraulic surface against the closing direction of the fuel. All hydraulic forces on the anchor sleeve can then act in the radial direction without affecting a position of the anchor sleeve in the axial direction or exert a hydraulic force on this anchor sleeve.

If an anchor sleeve is used, it is possible to receive a pressure pin for the hydraulic sealing of the interior of the anchor sleeve within the anchor sleeve, on the control chamber side facing the cavity within the anchor sleeve. The The inner space of the anchor sleeve can be configured in particular cylindrical, in particular as a circular cylinder and / or as a polygonal cylinder. The outer diameter of the pressure pin can be adapted to the inner diameter or the inner dimensions of this inner space, so that the pressure pin is mounted, for example, sliding and sealing within the interior of the anchor sleeve. The pressure pin, the anchor sleeve and a valve piece with an outlet throttle of the control chamber can then limit a valve space, wherein hydraulic forces act only on the pressure pin by the high pressure of the fuel within this valve space, but not on the anchor sleeve. In this way, a pressure balance can also be generated.

Also when using an anchor sleeve, it is preferred if the fuel injector comprises a valve piece, within which at least one outlet throttle of the control chamber is accommodated. In this context, an outlet throttle can generally be understood to mean an opening to the control chamber which, when the hydraulic valve is open, limits or controls the outflow of the fuel from the control chamber to a low-pressure drain.

It is particularly preferred if the valve piece has a, at least in the closed state of the hydraulic valve, projecting into the anchor sleeve approach, in particular a cylindrical approach. This approach can be adapted from its cross-section at least in sections on the inner dimensions of the interior of the anchor sleeve, so at least in sections, for example, in turn, have a circular cross-section, a polygonal cross-section or the like. In this way, the approach of the valve piece can also serve as a guide for the anchor sleeve, preferably a sealing guide is selected.

An orifice of the outlet throttle of the control chamber can be accommodated in particular in the approach. This mouth can be arranged, for example, at a remote from the control chamber end of the approach. Alternatively or additionally, however, the at least one orifice may also be received in a peripheral constriction of the neck. For example, the approach may initially comprise a first guide section, then the said constriction with the at least one mouth, and then a further guide section. The at least one guide section can be adapted from its outer diameter preferably to the inner diameter of the interior of the anchor sleeve, so for example, in turn, have said circular and / or polygonal cross-section.

Further preferred embodiments of the present invention relate to the configuration of the adjustment possibilities of the strokes and paths of the hydraulic valve. That's the way it is Particularly preferred when the anchor bolt is at least partially surrounded on a side facing away from the control chamber by an interchangeable shim, in particular a sickle disc. Such a shim, which can be stored, for example, in different thicknesses, can be used to allow adjustment of the overstroke of the hydraulic valve. Under an overstroke is here after switching off the Magnetaktors, a distance referred to which, after the anchor bolt has reached its seat and thus its closed position, the anchor plate still further moves due to their own inertia.

Also on the opposite, the control room facing side, a corresponding overstroke can be provided, in particular an adjustable overstroke. This overstroke stop can also be set up as an exchangeable overstroke stop, for example once again in the form of a replaceable disc or a ring. This overstroke stop can basically be provided between any part of the fuel injector, in particular the injector body, and the anchor plate. However, it is particularly preferred if the armature plate on its side facing away from the magnetic actuator side a guide extension, for example a cylindrical sleeve-shaped guide extension, wherein the fuel injector has a guide for receiving this guide extension. Between this guide, which, for example, part of a valve piece, in which the above-described outlet throttle of the control chamber is added, may be, and the guide extension, the at least one overstroke stop can be arranged. For example, as described above, it can be accommodated in the form of a replaceable disk between the guide and the guide extension.

Brief description of the drawings

Embodiments of the invention are illustrated in the drawings and explained in more detail in the following description.

Show it:

Figure 1 is a sectional view of a first embodiment of a fuel injector according to the invention;

Figure 2 is a plan view of an anchor plate of the embodiment of Figure 1; and Figure 3 is a sectional view of a section of a second exemplary embodiment of a erfϊndungsgemäßen Kraftstoffϊnjektors.

1 shows a first embodiment of a Kraftstoffϊnjek- sector 110 according to the invention in a sectional view with a cutting direction parallel to an injector axis 112 in a partial view is shown. The fuel injector 110 includes an injector body 114, which is shown only in a rudimentary manner in FIG. In the injector body 114, an injection valve member 116 is slidably mounted in the axial direction, of which only one valve piston 118 is shown in the sectional illustration according to FIG. The injection valve member 116 may be formed one or more members and serves to open or close at least one injection port, which is not shown in Figure 1.

At its upper end, the valve piston 118 is mounted in a sleeve extension 120 of a valve piece 122, so that a control chamber 124 is formed between the upper side of the valve piston 118 and the valve piece 122. This control chamber can be acted upon by high-pressure fuel via an inlet throttle 126, so that the pressure in the control chamber 124 controls a position of the valve piston 118 and thus a position of the injection valve member 116.

The valve piece 122 furthermore has an at least partially cylindrically configured valve body 128, which is supported on the injector body 114 downwards, that is to say in a closing direction of the injection valve member 116. A conical sealing shoulder 130 and, subsequent to the sealing shoulder 130, a cylindrical projection 132 of the valve body 128 are first received on this valve body 128.

In the valve piece 122, a discharge throttle 134 of the control chamber 124 is arranged. This drain throttle 134 comprises, starting from the control chamber 124, first an axial bore 136, followed by in this embodiment two obliquely to the injector 112 extending throttle bores 138. These throttle bores 138 each open into Mün- fertilize 140, which in a peripheral constriction 142 of the approach 132 are provided. Above the constriction 142, the projection 132 is widened again and has a guide section 144.

Via the outlet throttle 134, the control chamber 124 can be connected to a low-pressure drain (not shown in FIG. 1) so that a pressure in the control chamber 124 and therefore a position of the injection valve member 116 can be controlled by opening or closing the drain throttle 134 , To open or close the mouth 140 of the outlet throttle 134, a hydraulic valve 146 is provided in the fuel injector 110, which is designed as a solenoid valve. The hydraulic valve 146 includes a magnetic actuator 148 having a solenoid 150 and a magnetic core 152 which are arranged axially symmetrically.

Magnetic actuator 154 further comprises a magnetic armature 154. Magnetic armature 154 is acted upon by a force in the closing direction by means of a valve spring 158 mounted in a central cavity 156 of magnetic core 152. In the opposite direction, the armature 154 is acted upon by an armature spring 160, which is supported on the valve body 128 with a force opposite to the closing direction.

The armature 154 is designed in two parts in the illustrated embodiment and includes an anchor plate 162 and an anchor bolt 164th

At its end facing the magnetic core 152, the armature plate 162 has an armature plate 166 in the form of an axially symmetrical annular disk. In the closing direction, a cylinder sleeve-shaped guide extension 168 adjoins this anchor plate 166. The armature plate 162 cooperates with the magnetic coil 150 and can accordingly be made of a material optimized for magnetic actuation.

Within the guide extension 168, the anchor bolt 164 is slidably mounted in this embodiment. This anchor bolt 164 has an anchor sleeve 170 in the illustrated embodiment. This anchor sleeve 170 comprises a cylindrical inner space 172, in which the guide portion 144 of the projection 132 is slidably and sealingly mounted.

At its lower end, the anchor sleeve 170 has a sealing edge 174, which rests in the closed state of the hydraulic valve 146 shown in Figure 1 on the sealing shoulder 130 of the valve member 122 and forms a sealing seat. In this way, in the closed state shown in Figure 1 by the anchor sleeve 170, the outlet throttle 134 is closed, so that in the control chamber 124 high pressure is applied and the injection valve member 116 is pressed in its not shown in Figure 1 valve seat and closes the at least one injection port.

In this case, the hydraulic valve 146 shown in Figure 1 is designed as a pressure-balanced valve, as can act on the hydraulic valve 146, in particular the anchor bolt 164, in the axial direction no hydraulic forces. The pressure, which is out the control chamber 124 via the flow restrictor 134 transmits into the constriction 142 can act only in the radial direction on the inner walls of the anchor sleeve 170.

At its upper, the magnetic core 152 facing end of the anchor bolt 164 has a shim 176 which is inserted into a circumferential groove of the anchor sleeve 170. This shim 176 is configured in the illustrated embodiment, for example, as a sickle plate 178, as can be seen for example from a plan view of the armature 154 in FIG. The residual air gap disk 184 is not shown in this figure. The armature sleeve 170 has at its lower end, as shown in Figure 1, a shoulder 180 which limits the movement of the armature plate 162 down and which thus acts as an overstroke stop 182. For mounting the magnet armature 154, the armature sleeve 170 can first be inserted from below into the guide extension 168, whereupon the sickle disk 178 can be pushed into the groove in the armature sleeve 170 at the upper end. The valve spring 158 is supported in the illustrated embodiment on the sickle disc 178, but may alternatively be supported on other parts of the anchor bolt 164, for example, the anchor sleeve 170.

The armature spring 160 is supported at its upper end on the armature plate 166. However, another type of support is possible. The sliding support of the anchor sleeve 170 in the anchor plate 162 allows for relative movement between the anchor plate 162 and the anchor bolt 164, which is bounded upwardly by the sickle disc 178 and down through the shoulder 180. Furthermore, a residual air gap disk 184 in the form of one or more annular disks may be provided on the upper side of the armature disk 166, which can set a gap between the magnetic core 152 and the magnetic armature 154. Alternatively or in addition to the adjustment via the residual air gap disk 184, the residual air gap between the magnetic core 152 and the magnet armature 154 may also be designed as an air gap. Thus, for example, a stop for the anchor bolt 164 or the anchor sleeve 170 of the anchor bolt 164 also take place in a different form than by the use of a disc.

When the hydraulic valve 146 is actuated, magnetic force is applied to the solenoid actuator 148. The armature plate 162 is attracted upwardly by the solenoid 152 in FIG. The sickle plate 178, which is positively connected to the anchor bolt 164, acts as a driver and ensures that the anchor sleeve 170 is pulled by the anchor plate 162 with up. In this way, the sealing edge 174 is lifted from its seat on the sealing shoulder 130, so that pressure from the control chamber 124 can escape via the outlet throttle 134 in the low pressure drain and the injection valve member 116 can move in Figure 1 upwards to release the injection ports. To inject the injector member 116 and thus the Kraftstoffϊnjektor 110 to close again, the solenoid actuator 148 is turned off or the magnetic force is reduced, so that, driven by the valve spring 158, the anchor bolt 164 is pressed back into his seat and again in the control chamber 124 can build up a high pressure. The injection valve member 116 then closes again.

The residual air gap disc 184 may preferably be clamped under the sickle disc 178 so that the residual air disc 184 may be held in a defined position by the sickle disc 178. The anchor plate 162 is held between the injections by means of the armature spring 160 in a defined position or brought into such a defined position. The spring force of the armature spring 160 should be chosen as small as possible, preferably at a maximum of 3 to 4 Newtons. After the solenoid actuator 148 is turned off or downshifted in its magnetic force, the valve spring 158 pushes the anchor bolt 164 back into place as described above. As soon as the anchor bolt 164 has reached its seat, the armature plate 162 continues to lower due to its inertia move. This route is also referred to as an overstroke and is designated by a in FIG. Further sizes x (thickness of the sickle plate 178), z (axial length of the anchor plate 162) and y (distance between the upper edge of the sickle plate 178 and underside of the anchor plate 162) are also defined in FIG. Thus, the thickness x of the sickle disk 178 is calculated from the quantities a, y and z as x = a-y + z.

The overstroke a is limited by the overstroke stop 182, which in this case is formed by the shoulder 180 at the top of a collar 186 of the anchor sleeve 170. The excess stroke a should preferably not be greater than 10 microns. If, in individual cases, the tolerances of the individual parts of the dimensions relevant for the overstroke a are greater than the overtravel tolerance requires, it is possible to set the excess stroke a via an adjusting ring (measuring groups). In this case, prior to assembly, the dimensions indicated by y and z in Figure 1 must be measured and then a corresponding dial 176 (dimension x in Figure 1) selected.

FIG. 3 shows a second exemplary embodiment of a fuel injector 110 according to the invention. The construction and the mode of operation of the fuel injector 110 initially largely correspond to the construction and the mode of operation of the exemplary embodiment according to FIG. 1, so that reference may be made largely to the above description. In turn, the fuel injector 110 comprises an injector body 114, in which an injection valve member 116 is mounted with a valve piston 118. Above the valve piston 118, in turn, a control chamber 124 is formed in a valve piece 122, which can be acted upon by an inlet throttle 126 with high pressure. About an outlet throttle 134 in the valve member 122, the control chamber 124 is again pressure relieved, the Outflow throttle 134 in the embodiment shown in Figure 3, in contrast to the exemplary embodiment of Figure 1, only an axial bore 136 includes. This axial bore 136 opens into the interior of a cylindrical sleeve-shaped guide 188 of the valve piece 122 and can be closed or released by the hydraulic valve 146.

The hydraulic valve 146 is basically similar to the hydraulic valve 146 shown in FIG. In this case, in the representation according to FIG. 3, the magnetic actuator 148 is shown only partially, with only part of the magnetic core 152 being depicted. The magnetic coil 150, which may for example be configured analogously to FIG. 1, is not shown in FIG.

Again, the magnetic actuator 148 in the exemplary embodiment according to FIG. 3 comprises a magnet armature 154 with an armature plate 162 and an armature bolt 164. The armature plate 162 is again configured with an armature plate 166 and a guide extension 168. The guide extension 168 has at its lower end a constriction 190, which is cylindrical and corresponds to the inner diameter of the guide 188 from its outer diameter forth. The guide extension 168 is thus guided in the guide 188 of the valve piece 122.

In the cylindrical interior of the anchor plate 162 of the anchor bolt 164 is sealingly mounted and movable in the axial direction. The anchor sleeve 170 is in turn designed tubular and has at its lower end a seat edge 192, for example, a biting edge, a flat seat or a conical seat which is seated in the closed state shown in Figure 3 on a sealing seat 194 in the interior of the guide 188 of the valve seat 122 and a mouth 140 of the outlet throttle 134 seals.

In the interior of the tubular anchor sleeve 170, a cylindrical pressure pin 196 is received in the embodiment shown in Figure 1. This cylindrical pressure pin is supported at its upper end on the magnetic core 152 or another part of the magnetic actuator 148. From its outer diameter, the pressure pin 196 corresponds to the inner diameter of the tubular anchor sleeve 170, so that the anchor sleeve 170 is slidably mounted on this pressure pin 196, the pressure pin 196, however, ensures a pressure-tight seal of the control chamber 124. Due to the hydraulic pressure in the control chamber 124, which transmits through the outlet throttle 134 on the pressure pin 196, this pressure pin 196 is pressed up against the magnetic core 152.

Again, the anchor bolt 164 at its upper, the control chamber 124 opposite end on a driver in the form of a federal government. For example, this covenant can be may be configured as a dial 176 or a sickle disc 178 and may, for example, in turn, positively connected to the anchor sleeve 170. Alternatively or additionally, the collar can also be designed in other ways, for example as part of the anchor sleeve 170 itself. Under the sickle plate 178, a residual air gap disc 184 can again be arranged.

The mode of operation of the fuel injector 110 according to the exemplary embodiment illustrated in FIG. 3 largely corresponds to the mode of operation of the exemplary embodiment according to FIG. 1. Once again, the hydraulic valve 146 used is a pressure-balanced valve, since no hydraulic forces act on the armature 154 in the axial direction. As soon as the magnetic actuator 148 is energized, the armature plate 162 is attracted by the magnetic coil 150 and moved upward. Due to the collar in the form of the sickle plate 178 on the anchor bolt 164 and the anchor bolt 164 is pulled by the anchor plate 162 with up. The entrapment of the residual air gap disc 184 again serves to hold it in a defined position.

The anchor plate 162 is guided in the described upward movement by the guide 188 on the guide extension 168. By means of the armature spring 160, the anchor plate 162 is positioned in a defined position. Again, the spring force of the armature spring 160 should be as small as possible, for example, again at a maximum of 3 to 4 Newtons. By this upward movement of the anchor bolt 164, the mouth 140 is released and the control chamber 124 is depressurized, so that the injection valve member 116 can move upwards and can release at least one injection port.

To complete the injection process, the solenoid actuator 148 can be switched off or switched to a lower current. As a result, the valve spring 158 pushes the anchor bolt 164 back into its seat. Once the anchor bolt has reached the seat, the mouth 140 is closed, and the control chamber 124 is again acted upon by the inlet throttle 126 with high pressure, so that the injection valve member 116 back down moves and closes the at least one injection port.

Once the anchor bolt 164 has reached its seat, in turn, the armature plate 162 will continue to move down due to their inertia, so that in turn an overstroke a arises.

This overstroke a is limited by an overstroke stop 182. This overstroke stop 182 is formed by the upper edge of the guide 188 in the illustrated embodiment. Optionally, however, may be between the guide 188 and a shoulder 198 at the end The constriction 190 of the guide extension 168 of the anchor plate 162 may be provided with an exchangeable overstroke stop 182 in the form of an adjusting ring 200, as indicated in FIG. This adjusting ring 200 may in particular be configured as a replaceable adjusting ring, so that the overstroke stop 182 may be configured as a replaceable overstroke stop 182. Other embodiments of the overstroke stop 182 are conceivable, for example in that the shoulder 180 is not formed on the guide extension 168 of the anchor plate 162, but for example on the guide 188. Other types of overstroke stop or combinations of such overstroke stops are conceivable. Overall, the excess lift a should preferably again be no greater than 10 microns. The minimum overtravel a is limited by the maximum wear or the resulting anchor stroke drift in the valve seat. Typically, the wear or the Ankerhubdrift is less than 4 microns, so that the lower limit of the excess stroke a can be about 5 microns.

For the preferred tolerances can in turn be described in the above embodiment of Figure 1. The tolerances of the individual parts of the dimensions relevant to the overstroke a should in each case be greater than necessary in each case, so it is again possible to adjust the overstroke a via an additional adjusting ring, such as, for example, the adjusting ring 182, 200. In this case, the dimensions indicated in FIG. 3 with y and z would again have to be measured before assembly, so that the adjusting ring 200 can be selected correspondingly with the dimension x.

Claims

claims

A fuel injector (110) for injecting fuel into the combustion chamber of an internal combustion engine, in particular for use in accumulator injection systems, comprising at least one injection valve member (116) movably mounted in an injector body (114) of the fuel injector (110) for closing or releasing at least one injection port , further comprising at least one hydraulic valve (146), wherein the hydraulic valve (146) is arranged to control a stroke of the injection valve member (116) via at least one control chamber (124), the hydraulic valve (146) comprising a solenoid actuator (148 ) comprising at least one magnetic coil (150) and at least one magnetic armature (154), the magnetic armature (154) at least one armature plate (162) cooperating with the magnetic actuator (148) and at least one movably mounted relative to the armature plate (162) Pressure in the control chamber (124) controlling anchor bolt (164).

2. fuel injector (110) according to the preceding claim, wherein the anchor bolt (164) by means of a valve spring element (158) is acted upon by a force acting in a closing direction of the first force, the anchor plate (162) by means of an armature spring member (160) with a second, force acting against the closing direction, the second force being less than the first force.

3. Fuel injector (110) according to one of the preceding claims, wherein the anchor bolt (164) comprises an anchor sleeve (170), wherein the anchor sleeve (170) in the axial direction slidably on the anchor plate (162), in particular within the anchor plate (162). , stored.

4. fuel injector (110) according to the preceding claim, wherein in the anchor sleeve (170) a slidingly mounted pressure pin (196) for the hydraulic sealing of the anchor sleeve (170) on the control chamber (124) facing away from the side.

5. The fuel injector according to claim 1, further comprising a valve piece, wherein the valve piece comprises an outlet throttle of the control chamber, wherein 170), in particular an at least partially cylindrical approach (132).

6. Fuel injector (110) according to the preceding claim, wherein an orifice (140) of the outlet throttle (134) is received in the projection (132).

A fuel injector (110) according to the preceding claim, wherein the orifice (140) is received in a peripheral necking (142) of the lug (132).

8. Fuel injector (110) according to the preceding claim, wherein the projection (132) on the control chamber (124) facing away from the constriction (142) comprises a guide portion (144), wherein the outer diameter of the guide portion (144) to the inner diameter of the Anchor sleeve (170) is adapted.

9. fuel injector (110) according to any one of the preceding claims, wherein the anchor bolt (164) on a side facing away from the control chamber (124) is at least partially surrounded by a replaceable dial (176), in particular a sickle disc (178) to an adjustment an overstroke of the hydraulic valve (146) made possible.

10. fuel injector (110) according to any one of the preceding claims, wherein on the magnetic actuator (148) facing away from the armature plate (162) an overstroke (182), in particular a replaceable overstroke stop (182), for limiting an overstroke of the hydraulic valve (146 ) is provided.

11. Fuel injector (110) according to the preceding claim, wherein the armature plate (162) has on its side remote from the magnetic actuator (148) side a guide extension (168), wherein the fuel injector (110) has a guide (188) for receiving the guide extension ( 168), wherein between the guide (188) and the

Guide extension (168) of the at least one overstroke stop (182) is arranged.

12. Fuel injector (110) according to the preceding claim, wherein the guide (188) is formed as part of a valve piece (122), wherein the valve piece (122) at least one outlet throttle (134) of the control chamber (124).