WO2012084682A1

WO2012084682A1 - Magnetodynamic actuator and method for actuating a fuel injection valve

Info

Publication number: WO2012084682A1
Application number: PCT/EP2011/072902
Authority: WO
Inventors: Johann GÖRZEN
Original assignee: Continental Automotive Gmbh
Priority date: 2010-12-22
Filing date: 2011-12-15
Publication date: 2012-06-28
Also published as: DE102010063981A1

Abstract

The invention relates to a magnetodynamic actuator (10), in particular for a fuel injection valve. The actuator according to the invention comprises an electromagnetic stator (16) and a movable armature (13) made from a paramagnetic or diamagnetic material. The magnetic armature is repelled or attracted by the effect of eddy currents which are formed by the electromagnetic stator in the armature when a current flow is switched on or off. Furthermore, the invention relates to a method for actuating a fuel injection valve with a magnetodynamic actuator according to the invention, and to a fuel injection valve with a magnetodynamic actuator.

Description

description

Magnetodynamic actuator and method for actuating a fuel injection valve

The invention relates to a magnetodynamic actuator, in particular for actuating a fuel injection valve for an internal combustion engine, and a method for operating ei ^¬ nes fuel injection valve with a magnetodynamic actuator.

Fuel injection valves for internal combustion engines have üb ^¬ SHORT- a needle valve, the needle can be back position and forth by means of a controllable actuator between an open and a closed position. The controllable actuator provides an operating stroke, which is transmitted either directly or indirectly to the valve needle. In an indi rectly ^¬ driven fuel injection valve of Be ^¬ triebshub of the actuator is transmitted, for example via a servo valve to the valve needle. Known actuator types for this

Purpose are, for example, piezo actuators or magnetostatic (solenoid) actuators.

Conventional magnetostatic actuators have an electromagnetic stator and a movable ferromagnetic armature. The stator includes a coil and a ferromagnetic core ^¬ rule. As current flows through the coil of the stator, the stator exerts a magnetostatic attraction on the armature. By virtue of this static magnetic force, the armature can, in principle, be held on the stator as long as desired.

However, the electromagnetic stator can exert only an attractive force on the armature. To operate the valve in both directions, ie to open and close, is therefore a counterforce to deflect the anchor required. For the provision of a counterforce therefore usually a return spring is used. Since the ferromagnetic substances used in a conventional actuator are relatively heavy, correspondingly large magnetic forces and a correspondingly sized return spring are required. By the return spring, the movable mass is further increased, so that an even larger solenoid in the stator is required.

The problem with the known magnetostatic actuators is also the occurrence of eddy currents when switching on and off of the magnet. These lead to power losses and additional heat input in the actuator. In addition, the eddy currents lead to an inhibition of the movements of the anchor, especially during rapid movements. As a result, the mögli ^¬ che achievable dynamics of the actuator is limited. Conventional measures for the suppression of eddy currents, such as the use of soft magnetic, laminated material for stator and armature are not always possible or very expensive in the required fuel injectors ^¬ sizes, and in precision mechanics and microtechnology in general.

The movement in a conventional magnetostatic actuator is therefore based on two physical effects. The quasi-stationary, magnetostatic main effect (efficiency) consists in ferromagnetic attraction of stator and armature. The only transiently occurring magneto dynamic side effect (sturgeon ^¬ effect) is dynamic counter the main effect and limits this dynamic. This results in a maximum speed of the system. An additional problem arises because when the armature is energized by the coil of the stator, the armature is attracted with a force that increases exponentially as it moves towards the stator. When on ^¬ tightly to the stator, the armature therefore has a maximum Ge ^¬ speed and at the same time most attracted. This can lead to a rebound of the armature, which over time may result in deformation and wear of the armature.

The binary one hand by the exponential force characteristic and ^¬ other hand, by not realizable control measures be ^¬-related switching behavior of the magnetostatic actuator prevents course of injection molding, the so-called "Ra ^¬ te Shaping" in which the nozzle needle is only partially open. It is intended by controlling the injection rate be optimized during an injection of the combustion process in the combustion chamber.

Known solutions for injection rate shaping, for example, a method in which injectors via two rails and two valves with two different pressures ver ^¬ provides be. By appropriate control of the two Venti ^¬ le possibly with overlapping of the pressure curve at the nozzle can be influenced and thus loading the injection rate can be set. From DE 101 316 19 AI and EP 13 14 881 methods are also known in which an inlet throttle, which can be bridged via a second valve, the pressure profile at the nozzle can be influenced. In addition, inverse methods are known in which the injector is supplied with a low pressure and internally generates the higher pressure in a second stage. Here, the power ^¬ material is compressed not in an external high-pressure pump but only in the injector at the maximum injection pressure. The For this purpose, the jector is equipped with a hydraulic pressure booster and two solenoid valves. But such Lösun ^¬ gen for controlling the pressure in the injector are complicated.

The invention is therefore based on the object to provide an actuator and a method for actuating a Kraftstoffeinspritzven- tils, whereby the above problems can be at least partially avoided.

The object is achieved by a magnetodynamic actuator and by a method for actuating a fuel injection valve according to the independent claims. Vorteilhaf ^¬ te developments of the invention are specified in the dependent claims.

A magnetodynamic actuator according to the invention comprises an electromagnetic stator with connections for switchable connection to a power source. The stator can be connected to a power source via the connections so that a current flow through the stator can be impressed. A control unit allows the control of the current flow through the stator. The electromagnetic stator includes, for example, a coil having a ferromagnetic core.

The magnetodynamic actuator further comprises a movable armature having at least one electrically conductive portion. The armature is movably mounted at least between a first position and a second position. The first position of the armature is preferably a rest position of the armature, in which the electrically conductive portion of the armature has a minimum distance from the stator. In ^¬ example, the movable armature can rest in this first posi ^¬ tion directly on the stator. However, there must be no contact between the stator and the moving armature. The second position preferably designates a deflected position, in which the electrically conductive portion of the armature has a greater distance from the stator. This can for example be given by the fact that the armature is lifted from the stator. Depending on the arrangement and construction of the stator and the armature can in principle deflections from the rest position in different directions be possible. However, at least the armature is movable between a first and a second position, the displacement between each position representing an armature stroke. In the following, therefore, only a first position and a second position will be discussed. The armature is adapted during power ei ^¬ nes current through the electromagnetic stator, at least in the electrically conductive portion to form an eddy current so to under interaction with a

Stator magnetic field to be deflected from the first position. When an electric current is switched on by the electromagnetic stator, a magnetic field is formed

(Stator magnetic field) in this off. This is the anchor like flooded ^¬ genetically. The resulting magnetic field induced egg ^¬ NEN current flow in the movable armature in the form of vortex flow. According to Lenz's rule, these are so directed that they counteract their cause. Due to the eddy currents ^¬ the construction of the stator magnetic field by forming a second magnetic field (armature magnetic field) is hindered in opposite ^¬ modifying direction. The interaction of the two magnetic fields of electromagnetic stator and armature cause a repulsive force effect between the electromagnetic ^¬ 's stator and the movable armature. The movable anchor is initially located in the first Po ^¬ sition with a minimum distance between the electrically conductive portion of the armature and the stator, the armature (under the effect of the resulting magnetic fields when switching a current through the electromagnetic stator from the first position Rest position) deflected into a second position.

The armature is preferably mechanically coupled to an actuating element. Thus, a working stroke for the actuation of the actuating element can be ^¬ be riding provided by the deflection of the armature. The actuating element is beispielswei ^¬ se a valve element, in particular a valve element in a fuel injection valve. Basically, however, other fields of application of the actuator according to the invention are possible, for example for ABS, fast hydraulic valves, Pumpenven ^¬ tile or in a printing device.

In comparison with conventional magnetostatic actuators, the main effects and side effects of the magnetodynamic actuator according to the invention are thus reversed. The magnetostatic main effect which is mainly effective in the case of the conventional actuator becomes a useless disruptive effect in the magnetodynamic actuator according to the invention. Instead, according to the invention, the magnetodynamic effect is exploited as the main effect. While in the conventional magnetostatic actuators the

magneto dynamic interference effect limits the dynamics of the whole system because of its Hochpasscharak ^¬ ters, it is OF INVENTION ^¬ dung according rakters exploited as a main effect precisely because of its Hochpasscha- targeted. As a result, the dynamics of the actuator can be further increased. While conventional,

operate magnetostatic actuators with stationary magnetic fields, the magnetodynamic actuator according to the invention is based on magnetic field changes. According to the invention thus incurred in the armature vortex ^¬ streams are exploited, instead of fighting them.

Turning off the current through the electromagnetic stator reverses the entire process. By characterized occurring change in the stator magnetic field, in turn, eddy currents are induced in the armature, but this time with a swept to ^¬ polarity, so that a reverse magnetic field (armature magnetic field) is formed, which results in interaction with the stator magnetic field to an attraction of the armature. The movable armature is therefore preferably arranged to form eddy currents even during a turning off of the electric current by the electromagnetic stator and to be moved under the action of a magnetic field of the electromagnetic stator from a second (deflected) position to the first position.

In the magnetodynamic actuator according to the invention, therefore, the armature can be both attracted and repelled. Both repelling and attracting effect of the armature are each ^¬ weils caused by the changes in the current flowing through the electro-magnetic stator ^¬ and a resultant magnetic field of the stator magnetic ^¬ change. The repulsive and attractive effect is always only by a dynamic stimulation.

In the novel magneto-dynamic actuator the repulsive force is strongest immediately after switching on the current interim rule ^¬ stator and armature. Over time, the force decreases as the eddy currents in the armature decay due to the electrical resistance in the material. If the armature were superconducting, the eddy current in the armature would flow infinitely for a long time and the repulsive force effect would have a correspondingly long effect. However, in the real material of the anchor exists a finite electrical resistance which leads to a decay of the eddy currents. The decay of the eddy currents in An ^¬ ker also leads to a decrease in the armature magnetic field and thus to a decrease in the repulsive force. After a correspondingly long period of time, the armature would thus rest on the stator after the repulsive force had subsided. Only by further increasing the stator current could the repulsive force continue to be sustained. However, in the frequencies necessary for fuel injection valves for actuating the injection valve, the decrease of the repulsive force does not play a major role.

This effect, that the respective attractive or repulsive force at the beginning of the step is maximum and then decreases, also offers a further advantage of the magnetodynamic actuator according to the invention. The anchor is thereby fully accelerated immediately at the beginning, but bounces later, e.g. When pulling on the armature, it does not affect the stator so much ("soft landing") .This "soft landing" offers the added advantage that it can be further improved in terms of control and regulation, since it does not have to handle unstable states like at

magnetostatic actuator. A bouncing of the armature can thus be better avoided or at least reduced, thereby significantly reducing the risk of permanent deformation of the armature.

Another advantage is that the magnetic ^Ab¬ push stable and largely linear, while the magnetostatic attraction is a highly unstable non-linear process. Such operations are brisk ^¬ lung technically easier to control faster and more robust. Specifically, the free floating of an anchor, in which the hover height is significantly smaller than its dimension, is during magnetic tightening control technically extremely difficult. In magnetic repulsion, on the other hand, there are processes that are much more benevolent and therefore easier to control.

The instant high acceleration of the armature at every step, that is, every time the armature is repulsed and tightened, further increases the dynamics of the system. The time ^¬ behavior of the actuator can be adjusted by the material composition of stator and armature and by the current flow in the stator.

According to the invention, the armature has at least one electrically conductive partial region in which the eddy currents can form. Preferably, the anchor is made of a para or diamagnetic material. Particularly preferably be ^¬ is the anchor of a material having a high electrical conductivity. By a good electrical conductivity ^¬ ness of heat input is limited in the armature and the decay of the eddy currents ^¬ time is prolonged. Thus, the

magneto-dynamic effect, which is inventively exploited for Anzie ^¬ hen and repelling the armature further strengthens ^¬ ver. The magnetostatic effect, on the other hand, is reduced. The timing of the actuator and thus the dynamic effect can be easily and selectively adjusted by the conductivity of the anchor material. Paramagnetic materials with high electrical conductivity, for example, aluminum or copper ^¬ minium.

The stator and armature of the magneto-dynamic actuator of the invention are preferably configured and arranged such that the stator magnetic field, at the location of the armature is the electrically conductive portion of the armature in the first positi ^¬ on that respect is in the rest position, unbalanced.. The stator magnetic field is substantially stationary connected to the stator. The armature magnetic field, which is generated by the We ^¬ belströme in the anchor, however, is substantially stationary connected to the anchor. Upon movement of the armature, the armature magnetic field moves with. At the anchor's location, the stator magnetic field and the armature magnetic field overlap. An on ^¬ due to the asymmetry of the stator magnetic field is created

Enegiegefalle, resulting in a force for the deflection of the armature from the rest position results. Therefore, the armature is deflected when switching on the current through the electromagnetic stator from its rest position.

According to a preferred development of the magnetodynamic actuator, the actuator consists-apart from the conductive subregion-substantially of an electrically non-conductive material. The electrically conductive portion is then formed, for example, by short-circuiting rings made of an electrically conductive material, so that eddy ^¬ currents can form in the anchor. The short-circuit rings in the armature need not be configured in a circular manner. You only need to allow a closed circuit inside the armature to form eddy currents. However, the shorting rings can also be configured rectangular, triangular or in any other closed form.

Such short-circuit rings can for example be formed by crosswise arranged holes in the armature, which are poured through an electrically conductive material, an advantage of this development is that the position of the eddy currents in the armature can be selected specifically. This allows a direction of the deflection of the armature from the rest position set specifically. In a further preferred development of the ferromagnetic stator core is shaped so that when turned ^¬ have switched off the current flow through the coil of the magnetic north and south poles of the magnetic field therein propagating opposite to and with each other. The ferromagnetic core thus forms a U-shape or horseshoe shape, or an incomplete ring with a recess. At the recess of the ring face two end faces of the ferromagnetic core and form a magnetic north and south pole. In this arrangement, the direct distance between the north and south poles outside the ferromagnetic core, that is, in the gap between the north and south poles, is small compared to the distance between the north and south poles inside the ferromagnet passing through the ring. The ring formed by the stator core, incomplete does not have to speak to the geometric shape of a ring ent ^¬. Rather, the stator core can also be rectangular or triangular or take any other closed form that is interrupted at one point. At the interruption a gap is formed, on which end faces are opposite, which form the north and south poles of the Magnetfel ^¬. The rest position of the anchor is located in the gap between north and south pole. In an asymmetric ^{Ausgestal ¬} tion of the armature with integrated short circuit rings, the direction in which the anchor is to be deflected to be adjusted. For example, the shorting rings of the armature can be arranged outside of the stator ring, so that a repulsion of the armature from the center of the stator takes place. On the other hand, the shorting rings in the armature can be offset inwardly from the ring formed by the stator, so that when turning on the current through the Stator force is generated on the armature towards the center of the stator. This effect can be generated not only by short-circuit rings arranged asymmetrically in the armature, but also generally with an electrically conductive partial area arranged asymmetrically in the armature.

The magnetodynamic actuator according to the invention is particularly suitable for actuating a fuel injection valve of a combustion engine ^¬ . A fuel injection valve with a magnetodynamic actuator, as described above, is therefore an independent subject of the invention. In this case, the armature is coupled to an actuating element in the fuel injection valve. By means of a movement of the armature, an operating ^stroke for actuating the actuating element is provided. The actuator may, for example, a

Servo valve element, a control piston or a valve needle of the fuel injection valve. With a servo valve, the operating stroke provided by the actuator can be transmitted hydraulically to the valve needle of the fuel injection valve. Thus, the operating stroke of the geometry of the fuel injection ^¬ fuel valve can be adjusted. In a preferred variant, however, the armature of the magnetodynamic actuator is coupled directly to a valve needle of the fuel injection valve or the control piston for actuating the valve needle. This allows a faster reaction time between actuation of the actuator and the fuel injection valve.

A method for actuating a fuel injection valve for an internal combustion engine with a magnetodynamic actuator, which comprises an electromagnetic stator and a movable armature with at least one electrically conductive portion, is a further independent subject of the invention. In accordance with the method according to the invention, a

Current flow through the electromagnet of the stator switched ^¬ tet, whereby a stator magnetic field in the stator and a Umge ^¬ tion thereof is generated. This stator magnetic field induces an electrical eddy current in the electrically conductive subregion of the armature. The eddy current in the armature generates an armature magnetic field in the armature. By the interaction of the stator magnetic field and the Ankermagnetfel ^¬ of a force produced on the armature, which is carried out to a deflection of the armature from a first position in the vicinity of the stator in a second position. For Actu ^¬ tion of the fuel injection valve is by the

magnetodynamic actuator transmit the deflection of the armature to a valve element of the fuel injection valve. The valve element may be the valve needle of the Kraftstoffein ^¬ injection valve, or a valve element of a

Servo valve for indirect control of the fuel injection valve. The magnetodynamic actuator according to the invention is suitable not only for the deflection of the armature from the first position to the second position, but also for actuation in the opposite direction. Therefore, the invention ^shown SSE method in a preferred development includes moving sätzlichen steps in which the current flow through the

Electromagnet stator is turned off or reversed, whereby the first magnetic field in the electromagnetic stator decreases. By this change of the first

Stator magnetic field, in turn, an electrical eddy current is induced in the electrically conductive portion of the armature. This induced eddy current has the entgegenge ^¬ sat polarity when switching on the current flow induced by the stator eddy current in the armature. In a corresponding manner, the eddy current in the armature when switched off the current through the stator, a magnetic field with reversed polarity, which leads to a deflection of the armature in entge ^¬ gengesetzter direction. Accordingly, the armature is deflected from the second position and moved to the first position. While the magnetic fields produced by the stator when the current is turned on cause repulsion of the armature from the stator, when the current is turned off, magnetic fields are generated which cause an attractive force on the armature.

The inventive method for operating a motor ^¬ injection valve with a magneto-dynamic actuator has an advantage over conventional magnetostatic

Actuators that can be realized in principle shorter opening and closing times and higher speeds. The high speeds at which the actuator according to the invention and thus the fuel injection valve can be ^¬ drive, also can be used in a preferred embodiment of the method for injection course formations, as described below.

The electromagnetic stator or its coil has a specific inductance. The magnetodynamic actuator is preferably driven by a control unit. The inductance in the stator can then form an electrical resonant circuit with a capacitance in the control unit. As a result, a periodic switching on and off of current flow relationship ^¬, an alternating electric current in the electromagnetic stator can be realized.

According to a particularly preferred embodiment of the method according to the invention, therefore, the current flow through the electromagnetic stator is changed periodically. The change can be made by a periodic switching on and off, a periodic change of polarity or by applying an AC voltage. The AC voltage may be sinusoidal, for example. Due to the physical effects described above, the periodic variation of the current flow also repels and attracts the armature periodically. As a result, the armature can be put into mechanical vibration. This mechanical oscillation of the armature can in turn be transferred to a valve element of the fuel injection valve, so that a pulsed opening and closing of the fuel injection valve becomes possible.

Such pulsed opening and closing of the fuel valve can be used for example for performing multiple injections. On the frequency with which the system is set in vibration, the Einspritzra ^¬ te, and thus also the course of injection can be formed.

The electrical oscillating circuit, consisting of a Induktivi ^¬ ty in the stator and a capacity in the control unit is thus connected in the inventive system via a resilient, magnetically-mechanical coupling to an oscillatory mechanical system. The elastic, magnetic-mechanical coupling is formed by the magnetodynamic actuator and the valve. In this case, the electromagnetic oscillation is transferred to a mechanical oscillation movement of the armature. This in turn can be transmitted via an elastic mechanical coupling to the valve element of the Kraftstoffein ^¬ injection valve.

This series coupling oscillatory systems may be coordinated so that an energy-optimal overall ^¬ system with the highest possible dynamic formed. Operation with sinusoidal excitation additionally reduces parasitic effects. Especially by a sinusoidal excitation you can operate tuned resonant circuits in the range of their resonance. Thanks to this harmonious operation, significantly more actuator strokes can be realized than with previous ones

Actors.

As a result, the injector can be reduced and optimized so that it only delivers discrete subsets with constant opening times. The desired amount of fuel is then no longer realized over the drive time, but over the pattern and the number of injection pulses.

In the following, the invention will be explained in more detail with reference to the ^exemplary embodiments illustrated in ^FIGS . 1 to 6.

They show schematically:

Figure 1: the structure of a directly driven injector with an injection valve and a magnetodynamic actuator according to the invention;

2 shows a sectional view through a first form of execution ^¬ magneto dynamic invention

Actor;

3 shows a sectional view through a second embodiment of the magnetodynamic according to the invention

Actor;

Figure 4 is a sectional view through a third form of execution ^¬ magneto dynamic invention

Actuator with shorting rings;

5 shows a sectional view through a fourth magneto dynamic execution ^¬ of the inventive

Actor;

Figure 6: a vibration system comprising an electrical

Oscillating circuit, a magnetic-mechanical coupling by the magnetodynamic actuator and an elastically mechanical coupling to the valve element of a fuel injection valve;

FIG. 7 is a graphical representation of a pulsed injection for realizing various injection rates;

FIG. 8 is a graph of pulsed injection with fluctuating rail pressure; and

FIG. 9: a graphical representation of the time course of various states of the magnetodynamic

Actuator in one embodiment of the inventions ^¬ inventive method.

1 shows schematically the structure of a directly angetriebe- NEN injector having a fuel injection valve 21 and ei ^¬ nem inventive actuator 10. The fuel injection valve 21 includes a nozzle body having a Düsennadelausnehmung in which a nozzle needle is movably mounted, and from which extend a plurality of injection holes for combustion chamber 22 reach out. With a closed injection valve 21, the SI ^¬ nozzle needle forms a sealing seat with a nozzle needle seat in the recess. When the fuel injection valve 21 is open, the nozzle needle is lifted from its sealing seat and pressurized fuel can flow from a supply line 34 through the nozzle needle recess and through the injection holes 33 into the

Burn combustion chamber 22 of an internal combustion engine. To open and close the fuel injection valve 21, the valve needle ^{¬ is driven} directly by the magnetodynamic actuator 10 according to the invention. Alternatively, an indirect control via a control valve is possible. A control unit

32 regulates the power supply to the actuator 10. The magnetodynamic actuator 10 is explained in more detail below with reference to the embodiments illustrated in Figures 2 to 6. Figure 2 shows a first embodiment of the inventive actuator. The magnetodynamic actuator 10 according to the invention comprises an electromagnetic stator 11 with a coil 15 and a ferromagnetic core 16. Adjacent to the core is a para- or diamagnetic armature 13 in a rest position 12a (solid line). Stator and An ^¬ ker are in this example substantially rotationally symmetrical ^¬ trained around a central longitudinal axis 24. The coil 15 of the electromagnetic stator 11 can be connected to a power supply. When a current is turned on by the coil 15, a magnetic field is generated in the ferromagnetic core 16 of the coil. As the magnetic field forms in the ferromagnetic core 16, eddy currents are induced by the change in the magnetic field in the para or diamagnetic armature. By eddy currents, a magnetic field is re ^¬ rum see because of Lenz's rule made of ^¬ which counteracts the magnetic field of the stator 16 opposed ^¬. By interaction of the two magnetic fields of

Stator 11 and armature 13 creates a repulsive force on the armature 13. The stator 11 is installed stationary. The armature 13, however, is movable. Due to the repulsive force effect between stator 11 and armature 13 due to the two magnetic fields of stator and armature, the movable armature 13 is deflected from the first rest position 12a into a deflected position 12b. The thus provided hub 23 (Dif ^¬ difference between the heights 12 a and 12 b) can be transferred to a valve element of a fuel injection valve 21 (Figure 1). The magnetodynamic actuator according to ei ^¬ ner second embodiment shown in Figure 3 comprises a stator 11 with a ferromagnetic core 16, which largely encloses a movable armature 13. The movable armature 13 is essentially pot-shaped and has a star-shaped pel 25 for transmitting the hub 23 to a valve element of the fuel injection valve 21. This embodiment of the actuator is essentially rotationally symmetrical about a central longitudinal axis 24.

The ferromagnetic core 16 of the stator 11 is located inside a coil 15 and is extended beyond it into the interior of the pot-shaped armature 13. At least the pot-shaped region of the armature 14 is made of an electrically conductive material. The ferromagnetic core 16 is not only extends across the interior of the coil 15 in the interior of at ^¬ kertopfes 14 into it, but also extends to the outside of the coil 15 to the outside of the cup-shaped portion 14 of the armature 13. Between the cup-shaped Region 14 of the armature 13 and the ferromagnetic core 16 of the stator 11 is only a narrow gap.

By turning on a current through the coil 15 of the stator, a magnetic field is generated in the ferromagnetic core 16. This is referred to below as the stator magnetic field. The stator magnetic field propagates throughout the ferromagnetic core 16 and is interrupted only by the narrow gap in which the cup-shaped portion 14 of the movable armature 13 is located. Due to the development of the magnetic field in the stator core and in the gap, an eddy current is induced in the cup-shaped, electrically conductive subregion 14 of the armature 13. By this eddy current, in turn, is a second magnetic field, the on ^¬ kermagnetfeld generated which counteracts the magnetic field of the stator sixteenth Due to the interaction of the two magnetic fields, a force is exerted on the armature 13. As a result, this is moved from its rest position 12a in a deflected position 12b. The deflection or the stroke 23 of the armature is limited in the example shown in Figure 3 by a lower boundary wall. This is formed for example by a valve body 28. The punch 25 protrudes through a recess of the valve body 28 for transmitting the armature lift 23 to a valve element.

Figure 4 shows a third embodiment of the Invention ^¬ proper magneto-dynamic actuator 10 with a movable armature 13, having electrically conductive portions which only fourteenth These are designed as shorting rings 14 in the armature 13. In addition to the short-circuit rings 14, the armature 13 in this case consists of an electrically non-conductive material. The electromagnetic stator 11 has a coil 15 and a ferromagnetic core 16, which extends in a horseshoe shape around the movable armature. The two legs of the horseshoe-shaped core terminate in two end faces which face each other. When the current flow through the coil 15, the two faces of the core 16 form the magnetic north and south poles 17, 18 of the Elect ^¬ romagneten 11. The field lines of the stator magnetic field running from the end face of the north magnetic pole 17 to the opposite end face of the south magnetic pole 18 . the movable armature 13 is disposed between the two end faces and is penetrated by the magnetic field of the stator by ^¬. The stator core 16 thus forms an incomplete ring with a recess in which the movable armature 13 is arranged. The ring can, as shown in Figure 4, also have a rectangular shape.

In the rest position of the armature 13, the short-circuit rings 14 are arranged asymmetrically with respect to the stator magnetic field. By a change of the stator magnetic field during on or Switching off the electric current through the coil 15 13 eddy currents are induced in the short circuit rings 14 of the armature. These in turn generate a magnetic counter ^¬ field, the armature magnetic field. According to Lenz's rule, the armature magnetic field counteracts the stator magnetic field.

The armature magnetic field is substantially stationary connected to the An ^¬ ker 13 and is deflected and moved with this. Since the armature magnetic field in the first rest position of the armature 13 is asymmetrical to the stator magnetic field, ei ^¬ ne force effect arises and the movable armature 13 is deflected from its rest position to a deflected position. By arranging the short-circuit rings 14 in the movable armature 13, the direction of movement of the deflection can be adjusted. In the example shown in Figure 4, the deflection from the center of the stator 11 to the outside (in the drawing down) take place. In the case of an arrangement of the short-circuit rings 14 toward the center of the stator 11, however, the direction of movement could also be toward the center of the stator 11.

Figure 5 shows a further variant embodiment of the OF INVENTION ^¬ to the invention the actuator 10. This variant is not rotationally symmetrical ^¬ configured. The stator 11 comprises a coil 15 and a ferromagnetic core 16. The movable armature 13 is arranged above the stator in this example. A deflection of the armature 13 takes place here from a rest posi ^¬ tion in a deflected position upwards. To transfer the armature stroke 23 to a valve element 22 of a fuel injection valve 21, a punch 25 of the armature 13 is guided through a recess in the stator core 16. Thus, a direction reversal of the actuator can be realized even with a simple construction of the actuator. The actuator according to the invention can be operated in an injector (Figure 1) with a Kraftstoffeinsprit zventil 21 as a vibratory system. Such a vibration system is shown schematically in FIG. It comprises an electrical resonant circuit 29, an elastic coupling 10 between the electromagnetic oscillation of the resonant circuit 29 and a mechanical oscillation, and an elastically mechanical coupling 30. The resonant electrical circuit 29 is formed by the coil 15 of the stator 11 with the inductance Li, and a capacitor Ci of a drive circuit. With R ^" , L ^' and C the line parameters are designated.

The magnetodynamic actuator 10 itself forms an elastic coupling between the electromagnetic oscillation of the resonant circuit 29 and a mechanical oscillation of the armature 13. It is determined by the inductance L2 of the on ^¬ kerstromkreises (eg in the short circuit rings) whose resistance R2 and the armature mass ni2. Via an elastically mechanical coupling 30, the mechanical movement of the armature 13 can be transmitted to a valve element 22 of the Kraftstoffeinsprit zventils 21. The valve ^¬ element 22 has the mass m ₃ and, for example, the Ven ^¬ tilelement 22 may be a servo valve or the valve needle of the Kraftstoffeinsprit zventils.

During operation, the energy stored on the intermediate circuit capacitor Ci runs as a traveling wave through the system up to the mass m ₃ . There, it is reflected net of work performed mechanical work and travels back to the condensate ^¬ sator Ci. The central variable here is the eddy current in the armature 13, which is responsible for the repulsion and tightening of the armature 13. Especially with a sinusoidal excitation, one can operate the tuned oscillation systems shown in FIG. 6 in the region of their resonance. Such a harmonious operation can significantly increase the number of armature strokes per stroke compared to conventional actuators. For example, 30 to 100 anchor strokes per stroke are possible. The actuator according to the invention can therefore be operated much faster than conventional actuators. The fast switching speed achievable with the actuator according to the invention can be used for an exact control of the injection course and the injection quantity of an injector.

An injection can then be performed as a series of rapidly ^¬ successive individual injection pulses 38th The desired fuel quantity is then no longer realized via the activation duration but via the pattern and the number of individual injection pulses 38.

A fuel quantity of 32 mg could, for example, be realized with 32 pulses per 1 mg in a 128 pulse raster per crankshaft revolution. A corresponding injection pattern is shown in FIG. Due to the distribution in the injection window, even a true "rate shaping" would be possible.

At a speed of 3000 revolutions per minute or 50 1 / s, the overall system could be designed for example at 128 ^χ 50 1 / s = 6400 1 / s possible impulses. From an electrical vibration in each case two injection pulses can be triggered. Therefore, this requires an excitation frequency of 3200 1 / s. 2 pulses are thus apart 156 \ is, in each case only during 78 \ is actually ^¬ is injected. While the other 78 \ is pulsing the energy back to the intermediate circuit, which by the magnetodynamic actuator 10 is formed. From then on, the recovered energy available for the next injection pulse for Availability checked ^¬ supply back together with the newly supplied energy.

If, in a common rail injection system of a constant rail pressure, so evident with the Schwingungssys ^¬ tem with the inventive actuator 10, compared with conventional systems significantly reduced susceptibility to pressure variations in the In ektorleitungen. Figure 8 shows the course of a pulsed injection with pressure fluctuations in the rail or In ektorleitung. The pressure fluctuation is represented by the envelope of the injection pulses 38. Despite the pressure waves in the injector line, a total of 32 mg is injected by the individual pulses. For the post-injection, if only one DC link is available, it is possible to use gaps in the previous cylinder. For example, 32 mg for one cycle and 10 mg for filter regeneration are realized.

FIG. 9 shows by way of example in FIGS. A) to E) how different operating modes / injection characteristics can be achieved by controlling the actuator according to the invention. 9A) to 9E) show the time course of various operating states in 3 different phases of operation of the actuator according to the invention ^¬ carry up in the execution of the method for operating a fuel injection valve over time. FIG. 9A) shows the voltage Ui through the stator coil Li and FIG. 9B) the associated current flow Ii. With I ₂ (Figure 9C)), the short-circuit current is referred to in the anchor. The attractive or repulsive force between stator and armature is shown as F ₁₂ in Figure 9D). Figure 9E) shows the following Position (deflection) X2 of the valve element (valve needle or servo valve) and its speed V2. The Auslen ^¬ kung X2 of the valve needle corresponds to the Öffungszustand of the injector.

In a first phase in the time interval t <2, the injector is controlled so that the injection valve pulsating ^¬ net. In a second phase in the time interval 2 <t <4, the valve opens completely. In a third phase in the time interval 4 <t <6, a partial lift is realized. In a direct ^¬ th actuation of the valve needle through the inventive actuator without an intermediate servo valve that can

Partial stroke can be adjusted so that it comes to a Teileinsprit ^¬ tion in the combustion chamber. In the case of an injector with intermediate servovalve, on the other hand, the partial stroke can cause a pressure reduction in the common rail without triggering an injection.

Claims

claims

1. Magnetodynamic actuator (10), in particular for actuating a fuel injection valve of a Brennkraftmaschi ^¬ ne, comprising:

an electromagnetic stator (11) with connection elements (26) for switchable connection to an electrical current source (27),

an armature (13), which is movable at least between a first position (12a) and a second position (12b), comprising at least one electrically conductive portion (14),

- wherein the movable armature (13) is arranged currency ^¬ rend of turning on a current through the electromagnetic ^¬ rule stator (11) at least in the electrically conductive portion (14) form an eddy current so to under interaction with a stator magnetic field from the first Po - to be deflected (12a).

2. A magnetodynamic actuator (10) according to claim 1, wherein the movable armature (13) is adapted to form an eddy current during turning off or reverse polarity of the electric current through the electromagnetic stator (11) and under the action of a magnetic field from a second position (FIG. 12b) to be moved to the first position (12a).

3. Magnetodynamic actuator (10) according to one of the preceding claims, wherein the first position (12a) of the armature

(13) represents a rest position in which the electrically conductive portion (14) of the armature (13) has a minimum distance from the stator (11).

4. A magneto-dynamic actuator (10) according to one of the preceding claims, wherein the stator (11) and armature (13) so being ^¬ staltet and are arranged such that a during the switching on or off the current through the electromagnetic stator (11) developing Stator magnetic field at the location of the armature (13) in the first position (12a) is asymmetrical with respect to the electrically conductive portion (14) of the armature (13).

5. Magnetodynamic actuator (10) according to one of the preceding claims, wherein the movable armature (13) comprises a para or diamagnetic material.

6. The magnetodynamic actuator (10) according to any one of the preceding claims, wherein the armature (13) is made substantially of a non-electrically conductive material, and has integrated short-circuit rings (14) made of an electrically conductive material, which are suitable for the formation of eddy currents ,

7. Magnetodynamic actuator (10) according to any one of the preceding claims, wherein the stator (11) has a ferromagnetic core (16), in which a stator magnetic field is formed when the electromagnet is switched on, and which is shaped such that the magnetic north - (17) and south pole (18) of the stator magnetic field and zuei ^¬ point closer, with a direct path (19) between the north and south pole (17, 18) outside the ferromagnetic core is small compared to a distance (20) between North and South pole (17, 18) inside the ferromagnet (16).

8. Fuel injection valve (21) with a

Magnetodynamic actuator (10) according to one of the preceding claims, wherein the armature (13) with an actuating element (22) in the fuel injection valve (21) is coupled and by a movement of the armature (13) an operating stroke for Betä ^¬ tion of the actuating element (22) is provided.

9. A method for actuating a fuel injection valve (21) for an internal combustion engine with a magnetodynamic actuator (10) comprising an electromagnetic stator (11) and a movable armature (13) with at least one electrically conductive portion (14),

with the steps:

Turning on a current flow through the electromagnet (15) of the stator (11), and thereby generating a

Stator magnetic field in the electromagnetic stator (11) and an environment thereof,

- thereby inducing an electrical eddy current in the electrically conductive portion (14) of the armature (13), and thereby generating an armature magnetic field in the armature by this eddy current,

Deflection of the armature (13) from a first position (12a) into a second position (12b) by a force effect resulting from a superposition of the stator magnetic field and the magnetic field ^¬ an,

Transmitting the deflection (23) of the armature (13) to an actuating element (22) of a fuel injection valve (21).

10. A method of operating a fuel injection valve (21) according to claim 9, with the additional steps:

Switching off or reversing the current flow through the electromagnet (16) of the stator (11)

Inducing an electrical eddy current in the electrically conductive portion (14) of the armature (13), and thereby generating a second armature magnetic field in the armature, Deflection of the armature from the second position (12b) in the first position (12a) by a force effect resulting from egg ^¬ ner superposition of the stator magnetic field and the second to ^¬ kermagnetfeldes,

Transmitting the deflection (23) of the armature (13) to the actuating element (22) of the fuel injection valve (21).

A method of operating a fuel injection valve (21) according to claim 10, comprising the steps of:

peridodically changing the flow of current through the electromagnetic stator (11),

Excitation of the armature (13) in a mechanical vibration, transmission of the mechanical vibration of the armature (13) on an actuating element (22) of the Kraftstoffeinspritzven ^¬ tils (21) for periodically opening and closing the fuel injection valve (21) for performing multiple injections.