EP1763630B1 - Fuel injection valve - Google Patents

Abstract

Disclosed is a fuel injection valve for fuel injection systems of internal combustion engines, especially for injecting fuel directly into a combustion chamber of an internal combustion engine. Said fuel injection valve comprises a fuel inlet (12) that is designed for feeding fuel into the fuel injection valve and an electrically triggered actuating device (24) which cooperates with a valve arrangement (20) in order to discharge fuel into the combustion chamber in a directly or indirectly controlled manner via a fuel outlet (18). The actuating device (24) is provided with a solenoid arrangement (24a) which is to be supplied with power, a substantially magnetically soft magnet yoke arrangement (24b) that cooperates therewith, and a substantially magnetically soft magnet armature (24) which cooperates therewith. The magnet yoke arrangement (24b) is formed by at least two yoke disks (125). At least one face (127, 128) of each yoke disk (125) is provided with at least one pole web (25a, 25b) which acts upon the magnet armature arrangement (24c) along with the electric solenoid arrangement (24a1, 24a2). Each yoke disk (125) is composed of at least two partial yokes (125a) which contain soft metal and at least partly surround an actuating rod (22) that supports the magnet armature (24c).

Description

Background of the invention

The invention relates to a fuel injection valve for fuel injection systems of internal combustion engines, in particular for the direct injection of fuel into a combustion chamber of an internal combustion engine. In principle, it is possible to use the invention both in directly injecting and in conventional, injecting into the intake manifold engines.

The fuel injector of the present invention has a fuel inlet adapted to allow fuel to flow into the fuel injector and an electrically controllable actuator cooperating with a valve assembly to direct fuel in a directly or indirectly controlled manner through a fuel outlet to flow into the combustion chamber. In this case, the electromagnetic actuator to be energized solenoid coil assembly, cooperating with this substantially soft magnetic magnetic yoke assembly, and cooperating with this substantially soft magnetic magnetic armature arrangement.

The automotive internal combustion engine industry is faced with the challenge of optimizing the injection process of fuel into the combustion chamber to optimize the formation of pollutants at the place of their emergence due to the constantly increasing requirements of the exhaust emission legislation with further decreasing limit values. In particular, NO _x and soot emissions are critical. Through the development of injection systems with ever higher injection pressures and highly dynamic injectors, as well as by cooled exhaust gas recirculation and oxidation catalysts, it is possible to comply with current limit values. However, the potential of the previous emission reduction measures seems to have been reached. This puts variable injection curve shapes into the foreground. Here, the fuel injection rate is selectively varied by multiple injection or by selectively modulating the stroke of the nozzle needle.

State of the art

A fuel injection valve of the above type is known in a variety of designs from several manufacturers (Robert Bosch, Siemens VDO Automotive). However, these known arrangements have the disadvantage that the number of strokes per working cycle of the internal combustion engine is very limited. In particular, it is so it is not possible to provide the required number of high-speed internal combustion engines required for efficient engine management multiple injections per stroke. Also, the precise variation of the stroke of the valve needle is only very limited possible in these arrangements. In both respects, the conventional electromagnetic actuators have proven to be a limiting factor for the further development of efficient fuel injectors.

One known approach to overcoming this limitation is to provide a piezo linear actuator instead of the electromagnetic actuator. Apart from the high cost and the relatively large space required for the piezo linear actuator and their temperature-dependent behavior in the immediate vicinity of the combustion chamber of an internal combustion engine is disadvantageous. Also today's piezoelectric actuators allow only about 3 to 5 injection operations per power stroke of the internal combustion engine, with opening / closing cycles of about 100 microseconds can be realized. Overall, this type of fuel injection valves has previously been denied in the use of series vehicles on a larger scale. In addition, the stroke-travel of a piezo-linear actuator for a given length is very limited and is currently increased by means of complicated lever arrangements to about 100 to 200 microns. Finally, the precise modulation of the stroke of the nozzle needle by means of the piezo linear actuator with the high dynamics and the increasingly high pressures in the combustion chamber, especially in the diesel direct injection, still difficult.

From the DE 100 05 182 A1 an electromagnetic injection valve is known for controlling an amount of fuel to be fed into an internal combustion engine with an actuatable by an electromagnetic coil system valve body, wherein the valve body cooperates with a magnet armature of the electromagnetic coil system. The essential feature of this arrangement is that the electromagnetic coil system has at least two symmetrical to the central longitudinal axis and concentrically arranged coils with identical characteristics that are integrated into a magnetic circuit such that between two adjacent coils each have a first pole body is disposed, and the inner and outer Coil is adjacent to a second polar body. These polar bodies are arranged on the same side of the magnet armature. Furthermore, it is essential that the pole bodies are dimensioned such that a radial sectional area of a middle first pole body corresponds to the sum of the sectional areas of the adjacent second pole bodies. Overall, in this arrangement, the function depends significantly on the symmetry of the spatial design of the electromagnetic coil system. The time delay of the electrical and the magnetic Field construction depends primarily on the geometry of the magnetic circuit and in particular on the field diffusion and the eddy currents occurring.

However, the constructive and electrical / magnetic symmetry of the electromagnetic coil system required in this arrangement, such as the dimensioning or the ratio of the radial cut surfaces of the polar bodies, is a considerable limitation. In addition, the achievable valve switching times, valve paths and valve closing forces are also considered in this known arrangement the requirements explained at the outset may be described as inadequate at best.

From the DE 102 60 825 A1 For example, there is known a solenoid-operated fuel injection valve in which an opening area of a fuel passage, which is defined as a space between an inner surface of a container into which fuel is introduced and an outer surface of a needle member disposed in the container, is changed. For this purpose, the needle element is displaced in the longitudinal direction by tightening or magnetic forces generated by an electromagnetic device. The electromagnetic device is provided with a first and a second magnetic circuit, by which the tightening or magnetic forces are independently controllable.

Further prior art is from the documents, US 5,035,360 . US 4,156,506 US 5,207,410 ,, DE 2237 746.4 , and US 2001/0019085 known.

Patent Abstracts of Japan vol. 199 no. 3, 31 March 1999 such as JP 10 335139 A (Denso Corp) relates to a fuel injector having a fuel inlet, an electrically actuatable actuator cooperating with a valve assembly, a magnet coil assembly to be energized, a soft magnet magnetic yoke assembly cooperating therewith, and a soft magnetic magnet cooperating therewith Anchor arrangement comprises. The magnet yoke assembly is formed of three yoke discs. Each yoke disc has at least one of its end faces a pole web, which acts together with the solenoid coil assembly on the magnet armature assembly.

US 2004/118952 A1 (Nussio Randy ) relates to a yoke disc with a pole piece in an actuator of a fuel injection valve. The yoke disc has several partial yokes.

The No. 6,065,684 A (Varble et al ) relates to a fuel injector having a housing defining a fuel flow passage having an inlet (20) and an outlet, means for communicating the inlet with a fuel supply source at a controlled increased fuel pressure. An injector serves to selectively close and open the outlet for injecting the fuel through the outlet into a combustion chamber of an engine, the fuel pressure causing the valve to be urged in an opening direction. A return means urges the valve in a closing direction with a force that slightly exceeds the force exerted by the fuel pressure on the valve. An armature is connected to the valve and movable with it. First and second electromagnets are closely spaced at opposite sides of the armature, and when energized, magnetically pull the armature toward the respective electromagnet. When the first solenoid is energized, it generates a force sufficient to attract the armature and open the valve against the excess closing force of the return means. When the second solenoid is energized, it generates a force sufficient to quickly close the valve with the assistance of the return means against the force of the fuel pressure when the first solenoid is de-energized.

The invention underlying problem

This is the problem with known fuel injectors to provide a compact and cost-effective arrangement of a fuel injection valve, which is long-term stability and suitable for use in large series and a sufficiently high number of strokes per stroke of the internal combustion engine with the required opening / closing Is able to perform forces. The aim of the present invention is to provide fuel injection valves which can help to reduce the fuel consumption of internal combustion engines so as to increase the thermodynamic efficiency of the internal combustion engine.

Inventive solution

The invention solves this problem in a valve assembly of the type mentioned above by the features specified in claim 1.

Surprisingly, it has been shown that it is not necessary to switch from an electromagnetic actuator as a valve drive to a piezo linear actuator with all its own disadvantages and problems.

Rather, can be achieved by the inventive design of the components of the electromagnetic actuator that the fuel injection valve Not only the opening / closing forces required for petrol engines, but even the opening / closing forces required for diesel direct injection with considerably more strokes per stroke (about twice as many as a piezo linear actuator Today's design) can provide with an electromagnetic actuator. Furthermore, the overall arrangement builds at a small diameter outside diameter very compact at quickly provided high ÖfFnungs- / closing forces. The inventive design also allows a very efficient mass production with tight tolerances and low reject rate.

The valve assembly according to the invention allows the realization of opening / closing cycles with about 40 - 50 microseconds and less. This enables multiple injection processes for efficient engine management both for gasoline engines and for diesel engines. Moreover, it is also possible to increase the fuel throughput through the fuel injection valve in that with the valve arrangement according to the invention the stroke of the valve member with comparable stroke time can be about 3 to 6 times greater than in a piezo-linear actuator of today's design. In addition, the arrangement of the invention allows a very precise control of the course of the stroke over time.

Further developments and embodiments of the invention

In a preferred embodiment of the invention, each partial yoke cooperates with at least one spacer which at least co-determines a dimension of a cavity between two yoke discs. The spacer or spacers can either be arranged in the region of the outer lateral surface of the yoke disc or be supported between the end faces of two yoke discs. The spacers are either (laser) welded or glued to the partial yokes or the yoke discs. Alternatively, the spacers may also be made in one piece with the partial yokes or the yoke discs at least at one end.

Furthermore, electrical connecting pieces for the solenoid coil arrangement can be arranged or extend in the region of the outer circumferential surface of the yoke disc. Thus, the individual windings of the solenoid coil assembly can be energized in a simple manner.

Preferably, in each case the same side of the magnet armature assemblies facing solenoid coil assemblies for in-phase electrical drive in series or parallel connection are connected. This makes it possible to electrically open the valve assembly to open, close and hold, without a retaining spring is required. Under Holding spring is understood here to be a spring with a high spring constant, which is able to hold the valve arrangement against the operating pressures (of the supplied fuel or in the combustion chamber) in one position. This is to be distinguished from a spring which is able to ensure that the valve member remains in a closed position, so that no fuel flows through the valve arrangement into the combustion chamber when the valve assembly is de-energized and there are no operating pressures.

The invention makes it possible to open the valve assembly both electrically actuated, and to close electrically actuated and to hold in two positions - but also in intermediate positions - in which the corresponding arranged on both end faces of the armature assembly coil assembly is energized. This can also be achieved a deceleration or acceleration of the valve member on the way between the two end positions. This has the consequence that the valve member can be conveyed considerably "softer" into the valve seat or the opposite end position. This leads to less mechanical stress on the valve member or the valve seat, so that these components do not wear out so quickly. This allows a less robust dimensioning and a smaller diameter of the nozzle needle and thus a reduction of the necessary closing / holding forces. As a result, a more precise metering of the fuel and, because of the lower moving masses, a higher movement rate with more opening / closing cycles per working cycle than with piezo actuators is possible. In addition, the force-displacement behavior of a piezoelectric actuator is considerably less favorable and less influenceable than in an actuating device according to the invention.

In a first embodiment of the fuel injection valve according to the invention, the pole webs have a pitch which is about 2 to about 30 times, preferably about 5 to about 20 times, and particularly preferably about 10 times larger than a between the magnet yoke assembly and the magnetic Anchor arrangement formed air gap in a rest position of the actuator. The ratio between the pitch of the pole web, so a dimension which co-determines the magnetically active surface of the pole web, and the air gap is a function of the size of the valve significantly influencing size. The invention assumes that the ratio should be in the range of between about 2 and about 30, where any ratio between these limits is within the scope of the invention and primarily on the design conditions or requirements (available installation diameter, length, required valve lift, Valve member dynamics, etc.).

By the pole webs having a substantially asymmetrical to the central longitudinal axis of the fuel injection valve shape is avoided that manufacturing inaccuracies or Variations in the magnetic field generation, or temperature fluctuations lead to undesirable operating conditions. Rather, the non-rotationally symmetrical to the central axis of the design of the magnetic yoke or the magnetic coil so far is much less sensitive.

In one embodiment of the invention, the pole webs have a spiral shape to the central longitudinal axis of the fuel injection valve. In another embodiment of the invention, the pole webs have a substantially polygonal, preferably quadrangular or polygonal shape and are arranged side by side to form spaces for receiving the solenoid coil assemblies, wherein the pole webs are preferably arranged parallel to each other.

In the latter case, at least two adjacent pole webs can be surrounded by at least one electromagnet coil arrangement at least partially meandering. Alternatively, in each case each partial yoke can be formed from cobalt-iron-containing material and in each case have at least one pole web which is at least partially surrounded by at least one electromagnet coil arrangement.

A feature of the invention is that at least one electromagnet coil arrangement can at least partially enclose non-circularly shaped pole webs. This very efficient type of construction allows an embodiment; to arrange a current-conducting tape for forming the magnetic coil assembly and a soft iron-containing sheet metal strip to form a stator yoke back between the sheet containing soft iron between two layers. In this case, the current-conducting band and the soft iron-containing sheet-metal strip adjoin one another in each case on one longitudinal edge-electrically insulated.

In order to realize particularly slim or elongated designs with large holding or closing forces, a cascading of several valve drives along the axis of movement of the valve assembly is provided, wherein the actuator more than one assembly formed by the magnet coil assembly, the magnet yoke assembly, and the Magnetic armature arrangement comprises. These assemblies act together on the valve assembly - either in the same direction or in opposite directions - to lift the valve member from the valve seat or possibly also braked, hineinzubefern.

According to the invention, the actuating device acts on a movable valve member to this against a cooperating with the valve member and arranged downstream of the fuel inlet fixed valve seat between an open position and a Move closed position. Thus, a direct switching valve arrangement can be realized.

In another embodiment of the fuel injection valve according to the invention, the actuating device acts on a movable valve member to move it relative to a cooperating with the valve member fixed valve seat between an open position and a closed position. Thus, a controlled discharge of fuel in a return line is made possible when a second, spring-loaded valve member is not opened together with a second valve seat by the pressure prevailing in the combustion chamber, and allows a controlled discharge of fuel into the combustion chamber, when the second, spring-loaded valve member is opened together with the second valve seat by the pressure prevailing in the combustion chamber. Thus, an indirectly switching valve arrangement can be realized.

According to the invention, the magnet yoke arrangement and / or the magnet armature arrangement can be arranged eccentrically or asymmetrically with respect to a center axis of the fuel injection valve.

The individual ring coils may have a thickness of about 20 to about 80% of the yoke iron. In addition, the individual coils on one side of the magnetically soft magnet armature arrangement can be set up to be energized in opposite directions.

Furthermore, between the individual coils, the yoke iron can be formed by iron sheets insulated against each other at least on one side of the magnetically soft magnet armature arrangement.

The invention is based on the principle to orient the solenoid coil assembly and the magnet armature assembly substantially at right angles to each other.

According to the invention, the magnet coil arrangement and the magnet armature arrangement can at least partially, preferably completely overlap in the radial direction to the central longitudinal axis. This realizes a particularly efficient magnetic circuit that allows very small valve opening / closing times.

In one embodiment of the fuel injector according to the invention, the magnet yoke assembly may be a substantially cylindrical soft magnetic disk body be designed with radial or tangential to the central longitudinal axis oriented interruptions. These breaks may be simple slots or formed to increase the stability of the magnet yoke assembly by material having a higher magnetic resistance than the material of the soft magnetic disk body.

In another embodiment of the fuel injection valve according to the invention, the magnet armature arrangement can be formed by two or more spaced-apart strip-shaped soft magnetic sections. Again, the spatial separations may be simple slots or formed to increase the stability by material having a higher magnetic resistance than the material of the strip-shaped soft magnetic sections.

The magnet armature assembly may be a soft magnetic disc with recesses, preferably radially oriented, reaching to the edge of the disc slots, or elongated holes designed. Again, the reaching to the edge of the disc slots or slots can be simple recesses or be formed to increase the stability of material having a higher magnetic resistance than the material of the soft magnetic disc.

The magnet armature arrangement can also be constructed in multiple layers, with a ceramic layer being arranged between two soft iron layers. This layer structure is attached to the valve rod. To further improve the stability, the two iron layers can also be connected together along the outer circumference.

Furthermore, the soft magnetic armature assembly and the valve member can be interconnected and biased by a spring assembly in the open position or the closed position and bring by energizing the solenoid coil assembly in the closed position or the open position.

According to another embodiment of the fuel injection valve according to the invention also two of the above-described actuators may be provided which act in opposite directions on the valve member and bring this at respective energization in the closed position or the open position.

According to the invention, the actuating rod forms together thereon, usually (laser) welded magnet armature assemblies, a subassembly comprising at least a composed of stacked and spaced partial yokes formed further subassembly is composed.

Furthermore, according to the invention, a pressure-resistant housing surrounds the actuating device and the valve arrangement, out of which electrical connections for the solenoid coil arrangements are led out by means of glass feedthroughs. The glass bushings ensure a safe, fuel-tight and large-series, fuel-tight and with respect to the operating pressures (up to about 2000 bar) pressure-resistant arrangement for the electrical connections to the fuel injector safely.

Furthermore, according to the invention, the solenoid coil assemblies are formed as copper-containing moldings which are electrically insulated by ceramic coating, aluminum oxide coating, electrophoretic paint coating or the like, are mounted around the pole webs, and after assembly of the subassembly formed from individual stacked and spaced partial yokes electrical connections are connected.

Furthermore, according to the invention, the solenoid coil arrangements are cast or glued to the partial yokes. This increases the steady-state durability of the fuel injection valve assembly.

The fuel injection valve according to the invention can be set up and dimensioned to protrude into the combustion chamber of a foreign-fired internal combustion engine, or into the combustion chamber of a self-igniting internal combustion engine.

Finally, the invention relates to a mounting device with a mounting block, which has a number of yoke disks of the fuel injector corresponding number of axially spaced receptacles which are dimensioned so that the yoke members of the yoke discs are substantially free of play and remove, the axial Distances of the recesses substantially correspond to the axial extent of the cavity between two adjacent yoke discs, and allows welding, soldering or bonding of spacers with the yoke parts.

Further advantages, embodiments or possible variations will become apparent from the following description of the figures in which the invention is explained in detail.

Brief description of the figures

• Fig. 1 shows a schematic representation in longitudinal section through a fuel injection valve according to a first embodiment of the invention.
• Fig. 2 shows a schematic plan view of a cross section of a soft magnetic anchor assembly Fig. 1 , cut along the line II - II.
• Fig. 3 shows a schematic plan view of a cross section of a soft magnetic yoke assembly Fig. 1 , cut along the line III - III.
• Fig. 4 shows a schematic plan view of a soft magnetic yoke assembly with a magnetic coil assembly.
• Fig. 5 shows a schematic plan view of a soft magnetic yoke assembly and a magnet coil assembly according to a second embodiment of the invention.
• Fig. 6 shows a schematic plan view of a soft magnetic yoke assembly and a magnet coil assembly according to a third embodiment of the invention.
• Fig. 7 shows a side perspective view of the soft magnetic yoke assembly and the magnetic coil assembly according to Fig. 6 ,
• Fig. 8 shows a side partially cut longitudinal view of the valve rod with an anchor assembly having a box section.
• Fig. 9 shows a perspective side view of another embodiment of an actuating device according to the invention.
• Fig. 10 shows a partial yoke of a yoke disc for an actuator according to the invention after Fig. 9 in an enlarged perspective side view.

Detailed description of currently preferred embodiments

In Fig. 1 Fuel injection valve is shown with a to a central longitudinal axis M substantially rotationally symmetrical valve housing 10 in a schematic longitudinal section in a half-open position. Such a fuel injection valve is used for direct injection of fuel in the not further illustrated combustion chamber of an internal combustion engine. The fuel injector 10 has a radially oriented, lateral fuel inlet 12 through which pressurized fuel can flow into the fuel injector by means of a pump or other pressure transducer not further illustrated. However, it is also possible, the fuel inlet approximately at 14 indicated central in Fig. 1 Provide the upper portion of the fuel injection valve. From the fuel inlet 12, a central fuel passage 16 extends through a pipe 17 to a fuel outlet 18. At the end of the central fuel passage 16, a valve assembly 20 is provided to guide the fuel in a controlled manner through the fuel outlet 18 in FIG to let out the combustion chamber of the internal combustion engine.

The valve assembly 20 is formed by a valve member 20a located in the central fuel passage 16 and tapering toward the fuel outlet 18 and a valve seat 20b cooperating with the valve member 20a and configured in accordance with the shape of the valve member 20a.

The valve member 20a is connected via an actuating rod 22 with an electrically controllable actuator 24 to the valve member 20a between an open position and a closed position (in Fig. 1 move up and down). Thus, fuel coming from the fuel inlet 12 and flowing through the central fuel passage 16 is discharged in a controlled manner through the fuel outlet 18 into the combustion chamber in a controlled manner.

The actuating device 24 is formed by a solenoid coil arrangement 24a, a soft-magnetic magnet yoke arrangement 24b cooperating therewith, and a soft-magnetic magnet armature arrangement 24c cooperating therewith. In this case, the magnetically soft magnetic yoke arrangement 24b is formed from two shell halves 24b 'and 24b "which are joined approximately at the level of the section line II-II and have recesses 26a, 26b Fig. 1 in the plan view in the 4 and 5 shown longitudinal extent and are limited by also approximately trapezoidal or parallelogram-shaped pole webs 25a, 25b. In the recesses 26 a, 26 b, in each case a solenoid coil assembly 24 a 'and 24 a "was added, the flush with the respective end faces 27a, 27b of the shell halves 24b 'and 24b ".

The end surfaces 27a, 27b of the shell halves 24b 'and 24b "define a cavity 28 in which the magnet armature assembly 24c is movably received along the central axis M.

In the in Fig. 1 the arrangement shown, the solenoid coil assemblies and the Magnetjochanordnung the in Fig. 4 In the configuration shown, in which the pole webs 25a, 25b have a substantially quadrangular shape and are arranged side by side to form spaces for accommodating the electromagnetic coil arrangements 24a ', 24a ", the pole webs 25a, 25b are preferably arranged parallel to one another Magnetic yoke arrangement can here be formed of one-piece soft iron, from which the pole web or the interspaces are formed.In such a one-piece soft iron molding interruptions in the form of slots or slots can be incorporated, which are filled with electrically insulating material possible to produce the Magnetjochanordnung as a molded part of sintered iron powder or from several, possibly mutually insulated sections to assemble and, for example, to glue.

Fig. 2 shows the soft magnetic magnet armature assembly 24c. It has a soft magnetic armature disc 24c which is arranged around the central axis M around. In order to minimize the induced eddy currents in the armature disk 24c during operation of the fuel injection valve, the armature disk 24c is provided with radially oriented interruptions 36. These interruptions have the shape of reaching to the edge 30 of the armature disc 24c slots 36. This results in radially oriented strips 25 which are connected to each other in the center of the disc 24c.

Fig. 3 shows the soft magnetic magnet yoke 24b in cross section. In order to minimize the eddy currents induced in the magnet yoke arrangement 24b during operation of the fuel injection valve, the magnet yoke arrangement 24b is provided with a plurality of radially oriented vertical interruptions 36 in the form of slots. In order to make the fuel injection valve fluid-tight, a material web 38 is provided between the slots 36 on the outer wall, which ensures a closed lateral surface. Alternatively, the closed lateral surface may also be arranged at the radially inner ends of the slots 36. This also has the advantage of possibly improved heat dissipation from the yoke. Both shell halves 24b 'and 24b "of the magnet yoke assembly 24b are provided with the slots 36.

From the foregoing, it will be understood that the solenoid coil assembly 24a and the radially oriented tabs 25 of the soft magnetic armature disc 24c may be oriented substantially perpendicular to one another. It is understood that this can be realized either in the above-described form with radially oriented strips 25 of the armature arrangement 24b and a spiral-shaped solenoid coil arrangement 24a or magnetic yoke arrangement 24b, or vice versa. But it is also possible to realize the actuator 24 with concentric anchor parts and a star-shaped solenoid coil assembly.

Magnetic armature assembly 24c is a circular ferrous disk having a shape described in more detail below. The solenoid coil assembly 24a and the magnet armature assembly 24c overlap in the radial direction with respect to the central axis (M). Like in the Fig. 1 As shown, the solenoid coil assembly 24a has a smaller outer diameter than the armature disk 24c, so that the magnetic flux caused by the solenoid coil assembly 24a penetrates into the armature disk 24c with virtually no significant leakage losses. This results in a particularly efficient magnetic circuit that allows very low valve opening / closing times and high holding forces.

Regardless of the design of the magnetic yoke or of the magnet coil arrangement, the armature disk 24c can also be a closed disk made of soft iron, provided that the above-described embodiment of the magnet yoke or magnet coil arrangement ensures that the leakage losses or eddy current losses are low enough are the respective purpose.

As in Fig. 1 1, the armature disk 24c is rigidly connected to the actuating rod 22 and is longitudinally movably received in the pipe 17 along the center axis M in the pipe 17, in an armature space 34 bounded by the shell halves 24b 'and 24b "of the magnetic yoke assembly 24b is loaded with the actuating rod 22 by a coil spring 40 arranged coaxially with respect to the central axis M, so that the valve member 20a located at the end of the actuating rod 22 is seated in a fluid-tight manner in the valve seat 20b, ie is urged into its closed position during energization of one of the coils (for example 24a ') of the solenoid coil assembly 24a induces a low-turbulence magnetic field in the magnet yoke assembly 24b, which pulls the armature disk 24c with the actuating rod 22 toward the respective shell half 24b' in which the energized coil is located Valve member 20a of the valve seat 20b away in its open position. When the other coil (for example 24a ") of the solenoid coil arrangement 24a is energized, the valve member 20a moves into the other position toward the valve seat 20b in its closed position, an end of the actuating rod 22 remote from the valve member 20a acting coil spring 40 holds the valve member 20a when energized solenoid coil assembly 24a in its closed position.

One embodiment of the invention is to couple via the actuating rod 22 with the valve member 20a a plurality of (two or more) armature discs 24c, each acting on one or both sides of a coil yoke assembly. In addition, the coil arrangement 24a can be designed to be multi-part on both sides of the soft-magnetic magnet armature arrangement 24c. In each case, two or more solenoid coil assemblies 24a ', 24a "are provided which are substantially flush with the respective end faces 27a, 27b of the shell halves 24b' and 24b". This embodiment can have an increased magnetic field density and thus an increased valve member holding force and valve member operating speed for the same volume. Through the individual coils of a side (above or below) of the respective magnetic armature 24c alternately oppositely directed current flows. The yoke iron between the individual coils 24a of one side can be formed here by mutually insulated iron sheets.

The two embodiments are shown with electrically controllable actuators 24 in which a central actuating rod 22 is moved by a disk-shaped magnetic armature assembly 24c. It is also possible to provide a tube instead of the central actuating rod 22, on the end face of the magnet armature is arranged.

In the embodiment of the magnetic yoke or the magnetic coils according to Fig. 4 Every single pole is surrounded by a separate winding. Because of the better overview are in Fig. 4 not all pole webs provided with solenoid coil arrangements shown. In this case, all the solenoid coil assemblies 24a 'and 24a "either wound in the opposite direction and energized in the same direction winding in opposite directions to pass on opposite flanks 25a', 25a" of the pole webs 25a, 25b respectively oppositely directed electrical current.

Alternatively, it is also possible, the solenoid coil assembly in the in Fig. 5 shown configuration in which one (or more) windings meander in the recesses 26a, 26b between the pole webs 25a, 25b of the magnet yoke assembly is inserted (are). In this case too, in all embodiments the pole webs 25a, 25b (and also the recesses 26a, 26) have an electrical current directed in opposite directions to the middle longitudinal axis M of the fuel cell. Injector substantially asymmetrical shape, wherein at least one electromagnet coil assembly 24a ', 24 a "non-annular shaped pole web at least partially encloses so that on the edges of oppositely directed electrical current is passed.

The in the 6 and 7 shown embodiment of a solenoid coil assembly 24a is produced integrally with the cooperating with them soft magnetic yoke assembly 24b. For this purpose, a soft iron-containing, elongated yoke plate 50 is surrounded on both sides with a conductor strip 52 by this to a - in the later, finished state inside - longitudinal edge 50 'of the yoke plate 50 is folded over. In addition to the conductor strip 52 a soft iron-containing sheet metal strip 54 is arranged, which is just as thick as the conductor strip 52 and also to the - in the finished state inside - longitudinal edge 50 'of the yoke plate 50 is folded over. The metal strip 54 lying next to the conductor strip 52 serves, together with the section of the yoke plate 50 on which it rests flat, to form - in the finished state - the back of the magnetic yoke. The conductor strip 52 projects beyond the lateral longitudinal edge 50 "of the yoke plate 50 at both ends for electrical contacting, in the finished state, after which a second layer of a soft iron-containing, elongated yoke plate 56 is placed, so that a layer structure consisting of the first yoke plate 50, the conductor strip 52 and the sheet metal strip 54, and the second yoke plate 56. This layer structure is then in the in Fig. 6 shown spiraled together to obtain the existing of a coil and a yoke overall structure. After spirally rolling, the first and second yoke laminations 50, 56 are close together and the overall structure is a cylindrical former. It is understood that the conductor strip 52 is electrically insulated from the soft iron parts 50, 54, 56.

The in Fig. 1 shown, to the central longitudinal axis M coaxial air gap between the magnet yoke assembly 24b and the magnet armature assembly 24c in the rest position of the actuator 24 formed air gap is about 10 times greater than the pitch of the pole webs. The grid dimension in this embodiment is the transverse dimension of the pole webs. In the embodiment of the magnet yoke assembly 24b according to FIGS Fig. 6, 7 the grid dimension is the thickness of the yoke plate 40. Other geometries of the pole webs are also possible. Decisive for the pitch are the smallest structures of the pole webs, so their longitudinal dimensions, transverse dimensions, thickness, etc. which lead to a finely divided shape of the force acting on the magnet armature poles of the magnetic yoke. This small grid leads to high magnetic flux density and thus to high tightening or holding forces of the valve assembly and also to a low switching time, since the electrical and magnetic losses or the induced counter forces are very low.

In Fig. 8 is shown a further alternative for an embodiment of the armature assembly. The armature disk 24c is constructed in several layers. A ceramic layer 24c "is disposed between two relatively thin - and thus low-swirl - soft iron layers 24c 'to increase the mechanical stability and fastened to the valve rod 22. It is understood that the two soft iron layers 24c' either complete armature disks or recessed in the manner described above It is also possible for a plurality of such armature arrangements to be distributed along the valve rod 22.

Fig. 9 shows a partial view of a further embodiment according to the invention of the magnetic yoke assembly 24b, in which two substantially semicircular disc-shaped Teiljoche 125a are joined together to form a yoke disc 125 of the magnet yoke assembly 24b. In the center of each of two semi-circular disc-shaped Teiljochen 125 a composite yoke disc 125 is a semicircular cylindrical recess 125 '(see Fig. 10 ), which receives a bearing bush 126 for the valve rod 22. Thus, each yoke disc composed of at least two soft iron containing part yokes, which surrounds a magnet armature assembly carrying the actuating rod. The respective partial yokes of a yoke disc are glued together.

Each yoke disc 125 of the magnet yoke assembly - except the yoke discs at the two ends of the Jochscheibenstapels in Fig. 9 - Has at its two end faces 128, 130 each a Polsteg 25a, 25b, which acts together with the solenoid coil assembly 24a ', 24a' on the magnet-armature assembly 24c.The magnet armature assembly 24c is characterized by a corresponding number of the valve actuating rod 22 formed welded soft iron discs, which are provided with a plurality of bores through which fuel can flow when the magnetic armature assembly 24 c moves between their end positions.

Each Teiljoch 125a has formed in the region of its outer circumferential surface a spacer 130, which determines the dimension X of the cavity 28 between the two two yoke discs 125. Furthermore, 125 electrical connectors 132 for the solenoid coil assembly 24a ', 24 a "are arranged in the region of the outer circumferential surface of the yoke disc. Thus, in each case the same side of the magnet armature assemblies 24c facing solenoid coil assemblies 24a ', 24 a "connected for in-phase electrical control in series or parallel connection.

The arranged on the actuating rod 22 magnetic armature assemblies 24c thus form a subassembly which is to be assembled with the two formed from stacked and spaced partial yokes further subassemblies.

A pressure-resistant housing surrounds the actuator 24 and the valve assembly 20, are led out of the electrical connections from the electrical connectors 132 for the solenoid coil assemblies 24a ', 24 a "by means of glass ducts to the outside.

The solenoid coil assemblies 24a ', 24a "are formed as copper-containing molded parts electrically insulated by means of alumina coating or the like, which are mounted around the pole lands 25a, 25b and, after joining, stacked and spaced apart Finally, the solenoid coil assemblies 24a ', 24a "are shed in the recesses of the sub-yokes.

Claims (24)

1. Fuel injection valve for fuel injection systems of internal combustion engines, in particular for injecting fuel directly into a combustion chamber of an internal combustion engine, said fuel injection valve comprising

   - a fuel inlet (12) which is designed to allow fuel to flow into the fuel injection valve,

   - an actuating device (24) which can be electrically activated and cooperates with a valve arrangement in order to discharge fuel into the combustion chamber in a directly or indirectly controlled manner via a fuel outlet (18),

   - the actuating device (24) having a solenoid arrangement (24a) which is to be energized, a substantially magnetically soft magnet yoke arrangement (24b) which cooperates therewith, and a substantially magnetically soft magnet armature arrangement (24c) which cooperates therewith,

   characterized in that the magnet yoke arrangement (24b) is constituted by at least two yoke discs (125),

   - at least one of the faces (127, 129) of each yoke disc (125) has at least one pole web (25a, 25b) which together with the solenoid arrangement (24a', 24a") acts upon the magnet armature arrangement (24c), and

   - each yoke disc (125) is composed of at least two partial yokes (125a) which contain soft iron and at least partly surround an actuating rod (22) which supports the magnet armature arrangement (24c),

   - the magnetically soft magnet yoke arrangement (24b) has at least two conjoined shell parts (24b', 24b") with recesses (26a, 26b) in which there is accommodated a respective solenoid arrangement (24a', 24") which ends substantially flush with the respective end face (27a, 27b) of one of the shell parts (24b', 24b"), the end faces (27a, 27b) together delimiting the cavity (28) in which the magnet armature arrangement (24c) is accommodated so as to be movable along the central longitudinal axis (M) and,

   - the solenoid arrangement (24a', 24a") is constituted, on at least one side of the magnetically soft magnet armature arrangement (24c), by a plurality of solenoid arrangements.
2. Fuel injection valve according to claim 1, characterized in that

   - each partial yoke (125a) cooperates with at least one spacer (130) which at least concomitantly determines a dimension of a cavity (28) between two yoke discs (125).
3. Fuel injection valve according to claim 2, characterized in that

   - the spacer (130) or each spacer (130) is disposed in the region of the outer circumferential surface of the yoke disc (125).
4. Fuel injection valve according to any one of claims 1 to 3, characterized in that

   - electrical connecting pieces (132) for the solenoid arrangement (24a', 24a") are disposed in the region of the outer circumferential surface of the yoke disc (125).
5. Fuel injection valve according to claim 4, characterized in that

   - solenoid arrangements (24a', 24a") facing respectively the same side of the magnet armature arrangements (24c) are connected for co-phasal electrical activation in series or parallel connection.
6. Fuel injection valve according to any one of the preceding claims, characterized in that

   - the pole webs (25a, 25b) are of a shape which is substantially asymmetrical in relation to the central longitudinal axis (M) of the fuel injection valve.
7. Fuel injection valve according to any one of the preceding claims, characterized in that

   - the pole webs (25a, 25b) are of a substantially polygonal, preferably quadrangular shape, and are disposed next to one another so as to form intermediate spaces for accommodating the solenoid arrangements (24a', 24a"), the pole webs (25a, 25b) preferably being disposed in parallel to one another.
8. Fuel injection valve according to any one of claims 1 to 7, characterized in that

   - each partial yoke (125a) is made of a cobalt-iron-containing material and has at least one respective pole web (25a, 25b), which is at least partly surrounded by at least one solenoid arrangement (24a', 24a").
9. Fuel injection valve according to any one of claims 1 to 8, characterized in that

   - at least one solenoid arrangement (24a', 24a") at least partly encloses pole webs (25a, 25b) of non-circular shape.
10. Fuel injection valve according to any one of claims 1 to 9, characterized in that

    - the actuating device (24) has more than one assembly, constituted by the solenoid arrangement (24a), the magnet yoke arrangement (24b), and the magnet armature arrangement (24c), these assemblies acting jointly upon the valve arrangement (20) in the same or opposite directions.
11. Fuel injection valve according to any one of claims 1 to 10, characterized in that

    - the actuating device (24) acts upon a movable valve element (20a) of the valve arrangement (20), in order to move said valve element, in relation to a stationary valve seat (20b) which cooperates with the valve element (20a) and is disposed downstream from the fuel inlet (12), between an open position and a closed position.
12. Fuel injection valve according to claim 1, characterized in that

    - the individual coils are of a thickness of approximately 20 to approximately 80 % of the magnet-yoke iron present between two coils.
13. Fuel injection valve according to any one of the preceding claims, characterized in that

    - the individual coils are arranged on one side of the magnetically soft magnet armature arrangement (24c) to be energized in opposite directions.
14. Fuel injection valve according to any one of the preceding claims, characterized in that

    - the magnet armature arrangement (24c) is designed as a magnetically soft disc with recesses (38), preferably radially oriented slots or round or oblong holes extending to the edge (30) of the disc.
15. Fuel injection valve according to any one of the preceding claims, characterized in that

    - the magnet armature arrangement (24c) is of a multilayer structure, a ceramic layer (24c") being disposed between two soft-iron layers (24c') and being attached to the actuating rod (22).
16. Fuel injection valve according to any one of the preceding claims, characterized in that

    - the magnet armature arrangement (24c) and the valve element (20a) are connected to each other via the actuating rod (22), are biased to the open position or the closed position by a spring arrangement (40), and can be brought into the closed position or the open position as a result of the solenoid arrangement (24a) being energized.
17. Fuel injection valve according to any one of the preceding claims, characterized in that

    - the magnet armature arrangements (24c) are welded onto the actuating rod (22).
18. Fuel injection valve according to any one of the preceding claims, characterized in that

    - the magnet armature arrangements (24c) disposed on the actuating rod (22) constitute a sub-assembly which is to be assembled with at least one further sub-assembly constituted by stacked partial yokes (125a) that are held apart.
19. Fuel injection valve according to any one of the preceding claims, characterized in that

    - a pressure-proof housing surrounds the actuating device (24) and the valve arrangement (20), electrical connections for the solenoid arrangements (24a', 24a") being routed outwards from said housing by means of glass bushings.
20. Fuel injection valve according to any one of the preceding claims, characterized in that

    - the solenoid arrangements (24a', 24a") are realized as copper-containing preforms which are electrically insulated by means of ceramic coating, aluminium oxide coating, electrophoretic paint coating or the like; said preforms are mounted around the pole webs (25a, 25b) and, following joining together of the sub-assembly constituted by individual stacked partial yokes that are held apart, are connected to the electrical connections.
21. Fuel injection valve according to any one of the preceding claims, characterized in that

    - the solenoid arrangements (24a', 24a") are embedded in or bonded to the partial yokes (125a).
22. Fuel injection valve arrangement according to any one of the preceding claims, characterized in that

    - the fuel injection valve is designed and dimensioned to project into the combustion chamber of an externally ignited internal combustion engine.
23. Fuel injection valve according to any one of claims 1 to 14, characterized in that

    - the fuel injection valve is designed and dimensioned to project into the combustion chamber of a self-igniting internal combustion engine.
24. Assembly apparatus for producing a fuel injection valve according to any one of the preceding claims, said apparatus comprising an assembly block which has a number of receptacles which corresponds to the number of yoke discs (125) of the fuel injection valve, said receptacles being axially spaced apart and so dimensioned that the yoke parts (125a) of the yoke discs (125) can be inserted and removed in a substantially play-free manner, the axial spacings (X) of the recesses corresponding substantially to the axial extent of the cavity (28) between two adjacent yoke discs (125), and said assembly block allowing spacers (130) to be welded, soldered or bonded to the yoke parts.

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