EP0469385B1 - Magnet system - Google Patents

Magnet system Download PDF

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Publication number
EP0469385B1
EP0469385B1 EP91111897A EP91111897A EP0469385B1 EP 0469385 B1 EP0469385 B1 EP 0469385B1 EP 91111897 A EP91111897 A EP 91111897A EP 91111897 A EP91111897 A EP 91111897A EP 0469385 B1 EP0469385 B1 EP 0469385B1
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EP
European Patent Office
Prior art keywords
magnet
pole
magnetic
armature
permanent magnet
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP91111897A
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German (de)
French (fr)
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EP0469385A1 (en
Inventor
Jürgen Dipl.-Ing. Graner
Hans Dipl.-Ing. Kubach
Marcel Dipl.-Ing. Kirchner (Fh)
Günther Dipl.-Ing. Bantleon
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Robert Bosch GmbH
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Robert Bosch GmbH
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F7/00—Magnets
    • H01F7/06—Electromagnets; Actuators including electromagnets
    • H01F7/08—Electromagnets; Actuators including electromagnets with armatures
    • H01F7/16—Rectilinearly-movable armatures
    • H01F7/1638—Armatures not entering the winding
    • H01F7/1646—Armatures or stationary parts of magnetic circuit having permanent magnet
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F7/00—Magnets
    • H01F7/06—Electromagnets; Actuators including electromagnets
    • H01F7/08—Electromagnets; Actuators including electromagnets with armatures
    • H01F7/16—Rectilinearly-movable armatures
    • H01F2007/1676—Means for avoiding or reducing eddy currents in the magnetic circuit, e.g. radial slots
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F7/00—Magnets
    • H01F7/06—Electromagnets; Actuators including electromagnets
    • H01F7/08—Electromagnets; Actuators including electromagnets with armatures
    • H01F7/121—Guiding or setting position of armatures, e.g. retaining armatures in their end position
    • H01F7/122—Guiding or setting position of armatures, e.g. retaining armatures in their end position by permanent magnets

Definitions

  • the invention is based on a magnet system for solenoid valves for controlling liquids, in particular for fuel injection valves, of the type defined in the preamble of claim 1.
  • the known magnet system according to FIG. 1 has an electromagnet 1 with an excitation coil 2, which surrounds a cylindrical magnetic core 3 forming a magnetic pole with a pole face. Coaxial to the magnetic core 3, the excitation coil 2 is enclosed by a magnet housing 4 which, on the one hand, has a yoke 5 at which the Pole face away from the end face of the magnetic core 3 and on the other hand via a ring web 6 with a magnetic constriction 7 near the pole face of the magnetic core 3 with this magnetically conductive.
  • an armature 10 Opposed to the magnetic pole formed by the magnetic core 3 is an armature 10, which extends partially over the pole plate 9 and forms a working air gap 11 to the pole face.
  • the arrangement of the permanent magnet 8 and the flooding of the excitation coil 2 is such that the magnetic fluxes of the permanent magnet 8 and the electromagnet 1 in the working air gap 11 are opposite to each other.
  • the armature 10, which is firmly connected to the valve member of the solenoid valve, is of free-floating design. When the electromagnet 1 is not excited, it is held by the permanent magnet 8 against the hydraulic pressure acting on the valve member in the valve chamber on the magnetic core 3.
  • the magnetic flux of the permanent magnet 8 in the working air gap 11 is weakened, so that its holding force acting on the armature 10 decreases until the armature 10 lifts off from the magnetic core 3 due to the hydraulic counterforce and thereby opens the valve.
  • the magnetic flux generated by the excitation coil 2 is denoted in FIG. 1 by ⁇ E and the magnetic flux generated by the permanent magnet 8 by ⁇ P.
  • the magnetic flux ⁇ E is formed via armature 10, working air gap 11, magnetic core 3, yoke 5, magnet housing 4, permanent magnet 8 and pole plate 9 in two magnetic circuits symmetrical to the axis of the magnet system. Since the permanent magnet 8 has a permeability like that of air, it generates a relatively high magnetic resistance in the magnetic circuit of the electromagnet 1, which is increased by Driving power of the excitation coil must be compensated.
  • the cross-sectional area of the permanent magnet 8 is therefore made relatively large, while the thickness of the permanent magnet 8, which is thereby small, results from the required magnetic voltage and the greatest possible coercive field strength. Because of its larger area, the eddy current losses in the permanent magnet 8 also increase. Thin, large permanent magnets 8 are exposed to a considerable risk of breakage during their processing, which increases the manufacturing costs considerably. To reduce the eddy current losses, the permanent magnet 8 is made of cobalt samarium, which has a relatively low resistance, but is very brittle, so that the risk of breakage during magnet processing is further increased.
  • the free-flying armature 10 is lifted from the magnetic pole exclusively by the hydraulic back pressure acting on the valve member of the solenoid valve.
  • the hydraulic back pressure decreases strongly during the opening phase of the solenoid valve and sometimes even becomes negative.
  • a polarity reversing magnetic force would therefore be desirable to keep the valve open.
  • the magnet system according to the invention with the characterizing features of claim 1 has the advantage that the magnetic circuit of the electromagnet now closes via the opposite pole, the second working air gap, the armature, the first working air gap, the magnetic core, the yoke and the magnet housing, and thus the permanent magnet its great magnetic resistance no longer in Magnetic circuit of the electromagnet is.
  • the permanent magnet no longer needs to be dimensioned from the point of view of the minimized magnetic resistance.
  • the permanent magnet can thus be made thicker, so that its breaking strength is increased.
  • iron neodymium can now be used as a magnetic material, which is about twice as high-resistance with comparable magnetic energy and has not been considered so far because of its high temperature coefficient of remanence. Iron neodymium is not as brittle as cobalt samarium and is easier to process. Overall, the permanent magnet can be manufactured much more cost-effectively in the magnet system according to the invention.
  • a lifting force is exerted on the armature when the electromagnet is excited, which counteracts the attraction force of the permanent magnet.
  • the force acting on the armature of the permanent magnet and electromagnet decreases with increasing excitation of the electromagnet and finally becomes negative, so that the armature is not only removed from the magnetic pole by the hydraulic pressure in the solenoid valve, but additionally by an electromagnetically generated lifting force.
  • This negative magnetic force is desirable when using the magnet system in hydraulic valves, in particular fuel injection valves, because in these the valve member acts on the valve member Hydraulic pressure acting on the armature becomes very small during the opening stroke of the magnet system and is no longer sufficient to hold the armature in a defined end position in which the solenoid valve is open in a defined manner.
  • This "negative attraction force" on the armature is generated without reversal of current in the excitation coil of the electromagnet, so that an intervention in the control electronics is not necessary.
  • F max acts on the armature.
  • the dotted curve in FIG. 3 for the falling anchor can also be shifted along the flow.
  • the switchover points w ⁇ I on , w ⁇ I off at which the tightening force F is equal to the hydraulic force F hydr acting on the armature (when using the magnet system in a hydraulic solenoid valve) can be set in this way. Without magnetic tension at the stray air gap, they would be outside the desired range.
  • the hysteresis I an - I from the electrical excitation of the electromagnet, ie the excitation of the electromagnet required to move the armature from the two stop positions, is smaller by a factor of ⁇ 2 than in the known magnet system with otherwise identical data. This reduces the power required to control the hysteresis by half. This enables either a reduction in current and thus a reduction in eddy current losses or a reduction in the number of turns of the excitation coil and thus a reduction in its inductance.
  • the magnet system according to the invention is further characterized by a sufficiently large rate of change of the magnetic force acting on the armature via the excitation current. In order to the influence of variable forces F hydr is reduced. at the anchor stops on the switching time.
  • the end face of the magnet housing facing away from the yoke is connected to the magnet core near the pole face thereof via an annular web, preferably integral therewith.
  • the permanent magnet rests on the ring web and is held on it only by its magnetic force.
  • a magnetic constriction acting in the radial direction is introduced into the ring web.
  • the opposite pole with flux guide element is realized by a pole plate which is fastened to the magnet housing by means of a holder.
  • the holder is made of non-magnetic material or of soft magnetic material, eg nickel iron, with a Curie temperature of approx. 80 ° C.
  • the soft magnetic material is used when the permanent magnet is made of iron neodymium in order to exactly compensate for the high temperature response of the permanent magnet made of iron neodymium with the large temperature response of the low-lying saturation induction of the nickel-iron.
  • FIG. 2 schematically shows a longitudinal section of a magnet system for solenoid valves for controlling liquids, which illustrates the basic structure of the magnet system.
  • the magnet system consists of an electromagnet 20 and a permanent magnet 21.
  • the electromagnet 20 has an excitation coil 38 which surrounds a magnetic core 24 which forms a magnetic pole 22 with a pole face 23 and is in turn enclosed by a magnet housing 25.
  • the magnet housing 25 is close on the one hand via a yoke 26 with the end face of the magnetic core 24 facing away from the pole face 23 and on the other hand via an annular web 27 the pole face 23 connected to the magnetic core 24.
  • Magnetic core 24, magnetic housing 25, yoke 26 and ring web 27 are made of the same ferromagnetic material.
  • the ring-shaped permanent magnet 21 lies on the ring web 27 and surrounds the magnetic core 24. It is held on the ring web 27 exclusively by its magnetic force and covers only part of the surface of the ring web 27.
  • the permanent magnet can be made of iron neodymium.
  • a magnetic armature 28 is exposed to the magnetic pole 22 with the formation of a first working air gap 31 and covers a partial area of the permanent magnet 21 with the formation of a larger ring air gap 33
  • Armature 28 forms a second working air gap 32.
  • the opposite pole 29 with its annular pole face 30 is formed on a pole plate 35 which surrounds the permanent magnet 21 with an edge web 36 and is coupled to the ring web 27 and thus to the magnet housing 25 via an annular stray air gap 34.
  • the pole plate 35 is fastened to the magnet housing 25 with a holding element 37 and has a circular recess for the passage of a valve member to be connected to the armature 28.
  • the holding element 37 consists either of non-magnetic material or of soft magnetic material with a Curie temperature of approximately 80 ° C.
  • a soft magnetic material is nickel iron.
  • the latter is preferably used when the permanent magnet 21 is made of iron neodymium. With the large temperature response of the low-lying saturation induction of nickel iron, the high temperature response of the permanent magnet 21 made of iron neodymium can be exactly compensated for.
  • the flooding of the Excitation coil 38 of the electromagnet 20 and the arrangement of the permanent magnet 21 magnetized in the axial direction is such that the magnetic fluxes ⁇ E and ⁇ P from the electromagnet 20 and the permanent magnet 21 in the working air gap 31 are directed in opposite directions.
  • the two magnetic fluxes are formed symmetrically to the axis of the magnet system. For the sake of clarity, the respective magnetic flux is shown in FIG. 2 only in one half of the symmetry.
  • the magnetic flux ⁇ P of the permanent magnet 21 is divided into two partial fluxes ⁇ P1 and ⁇ P2 .
  • a leakage flux ⁇ P3 forms over the leakage air gap 34.
  • ⁇ p2 does not pass over armature 21 in region 67 of permanent magnet 21 projecting armature 28 and serves to bias the stray air gap 34 magnetically.
  • a magnetic constriction 40 is formed in the annular web 27 by introducing an annular groove 39.
  • This constriction 40 reduces the partial flux ⁇ P2 to a value which is optimal for controlling the flux in the magnetic core 24 in both directions.
  • the constriction 40 can be specifically saturated, so that a leakage flux of ⁇ E is prevented from flowing along this path.
  • the movement of the armature 28 is limited by stops, not shown here, so that a residual air gap remains between the pole faces 23 and 30 and the armature lying against the stop.
  • the ring air gap 33 is dimensioned approximately twice as large as the maximum working air gap 31 or the maximum working air gap 32, which corresponds to the maximum stroke of the armature 28.
  • the annular cross-sectional area of the permanent magnet 21 is made about 1.5 times larger than the sum of the pole areas 23, 30 of the magnetic pole 22 and the opposite pole 29.
  • a fuel injection valve is shown in longitudinal section, in which the described magnet system is used. As far as components correspond to those in Fig. 2, they are provided with the same reference numerals.
  • the magnet system is inserted in a screen housing 41 in which a fuel inflow 42 and a fuel outflow 43 are provided. Fuel inflow 42 and fuel outflow 43 are separated by an injected filter or strainer 44 from axial axial channels 45, 66, which extend to the pole plate 35 of the magnet system. A plurality of fuel guide pieces 55 are inserted between the axial channels 45, 66 (FIG. 5).
  • the pole plate 35 closes the screen housing 41 on the end face and is welded to the magnet housing 25 with non-magnetic or temperature-dependent magnetically saturated connecting pieces 46, which correspond to the holding element 37 in FIG. 2.
  • a valve body 48 passes through the circular recess 47 of the pole plate 35 and is fixedly connected to the armature 28. Concentric to the recess 47, the pole plate 35 carries on the side facing away from the armature 28 a recess 49, on which a valve seat 50 is formed, with which the valve body 48 cooperates to close and open the fuel injection valve.
  • the valve body 48 carries a circumferential groove 51, which is connected via radial slots 52 arranged in the pole plate 35 in the region of the passage opening 47 to a flow gap 53 which surrounds the armature 28 in a circular manner and which in turn is connected to the axial channels 66 via channels 56.
  • the fuel flow in channels 54 between the axial channels 45 and 66 should preferably cool the pole plate 35.
  • the fuel flow in the flow gap 53 cools the front area of the valve. In the event of a hot start, the liquid part of the fuel can collect below the channels 54 in the space 56 (FIG. 4) and separate from the gaseous components in such a way that only liquid fuel is injected.
  • the areas 57 of the screen housing 41 are resilient, so that the screen housing 41 presses against a stop 59 on the pole plate 35 regardless of the size of an O-ring 58.
  • the excitation winding 38 of the electromagnet 20 is carried by a coil former 60 and is connected to connection pins 61. These in turn are welded to connector pins 62 in a connector housing 63.
  • the connector housing 63 is firmly connected to the magnet housing 25 by a flange 64.
  • the magnetic core 24 with an integrally attached yoke 26 and excitation coil 38 are encapsulated in the magnet housing 25 by a potting compound 65.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Magnetically Actuated Valves (AREA)
  • Electromagnets (AREA)
  • Hard Magnetic Materials (AREA)
  • Soft Magnetic Materials (AREA)

Description

Die Erfindung geht aus von einem Magnetsystem für Magnetventile zur Steuerung von Flüssigkeiten, insbesondere für Kraftstoffeinspritzventile, der im Oberbegriff des Anspruchs 1 definierten Gattung.The invention is based on a magnet system for solenoid valves for controlling liquids, in particular for fuel injection valves, of the type defined in the preamble of claim 1.

Zum Beispiel in der DE 39 21 151 A1 (nicht vorveröffentlicht) ist ein solches Magnetsystem für ein Kraftstoffeinspritzventil angegeben (vergl. Fig. 3), das zur Verdeutlichung seines prinzipiellen Aufbaus in Fig. 1 skizziert ist.For example, in DE 39 21 151 A1 (not previously published), such a magnet system for a fuel injection valve is specified (cf. FIG. 3), which is outlined in FIG. 1 to illustrate its basic structure.

Das bekannte Magnetsystem gemäß Fig. 1 weist einen Elektromagneten 1 mit einer Erregerspule 2 auf, die einen einen Magnetpol mit Polfläche bildenden zylindrischen Magnetkern 3 umgibt. Koaxial zum Magnetkern 3 ist die Erregerspule 2 von einem Magnetgehäuse 4 umschlossen, das einerseits über ein Rückschlußjoch 5 an der von der Polfläche abgekehrten Stirnseite des Magnetkerns 3 und andererseits über einen Ringsteg 6 mit magnetischer Engstelle 7 nahe der Polfläche des Magnetkerns 3 mit diesem magnetisch leitend verbunden ist. Auf dem Ringsteg 6 sitzt koaxial zum Magnetkern 3 ein dünner, scheibenförmiger Permanentmagnet 8, der von einem ringförmigen Polplättchen 9 abgedeckt ist. Dem von dem Magnetkern 3 gebildeten Magnetpol liegt ein Anker 10 gegenüber, der sich teilweise über das Polplättchen 9 erstreckt und zur Polfläche einen Arbeitsluftspalt 11 ausbildet. Die Anordung des Permanentmagneten 8 und die Durchflutung der Erregerspule 2 ist so getroffen, daß die Magnetflüsse von Permanentmagnet 8 und Elektromagnet 1 im Arbeitsluftspalt 11 einander entgegengerichtet sind. Der mit dem Ventilglied des Magnetventils fest verbundene Anker 10 ist freifliegend ausgebildet. Bei unerregtem Elektromagneten 1 wird er von dem Permanentmagneten 8 entgegen dem in der Ventilkammer auf das Ventilglied wirkenden hydraulischen Druck am Magnetkern 3 angezogen gehalten. Mit Erregung des Elektromagneten 1 wird der Magnetfluß des Permanentmagneten 8 im Arbeitsluftspalt 11 geschwächt, so daß dessen auf den Anker 10 wirkende Haltekraft soweit abnimmt, bis der Anker 10 aufgrund der hydraulischen Gegenkraft vom Magnetkern 3 abhebt und dadurch das Ventil öffnet.The known magnet system according to FIG. 1 has an electromagnet 1 with an excitation coil 2, which surrounds a cylindrical magnetic core 3 forming a magnetic pole with a pole face. Coaxial to the magnetic core 3, the excitation coil 2 is enclosed by a magnet housing 4 which, on the one hand, has a yoke 5 at which the Pole face away from the end face of the magnetic core 3 and on the other hand via a ring web 6 with a magnetic constriction 7 near the pole face of the magnetic core 3 with this magnetically conductive. A thin, disk-shaped permanent magnet 8, which is covered by an annular pole plate 9, sits on the ring web 6 coaxially with the magnetic core 3. Opposed to the magnetic pole formed by the magnetic core 3 is an armature 10, which extends partially over the pole plate 9 and forms a working air gap 11 to the pole face. The arrangement of the permanent magnet 8 and the flooding of the excitation coil 2 is such that the magnetic fluxes of the permanent magnet 8 and the electromagnet 1 in the working air gap 11 are opposite to each other. The armature 10, which is firmly connected to the valve member of the solenoid valve, is of free-floating design. When the electromagnet 1 is not excited, it is held by the permanent magnet 8 against the hydraulic pressure acting on the valve member in the valve chamber on the magnetic core 3. With excitation of the electromagnet 1, the magnetic flux of the permanent magnet 8 in the working air gap 11 is weakened, so that its holding force acting on the armature 10 decreases until the armature 10 lifts off from the magnetic core 3 due to the hydraulic counterforce and thereby opens the valve.

Der von der Erregerspule 2 erzeugte Magnetfluß ist in Fig. 1 mit φE und der vom Permanentmagnet 8 erzeugte Magnetfluß mit φP bezeichnet. Deutlich ist zu erkennen, daß der Magnetfluß φE, sich über Anker 10, Arbeitslufspalt 11, Magnetkern 3, Rückschlußjoch 5, Magnetgehäuse 4, Permanentmagnet 8 und Polplättchen 9 in zwei zur Achse des Magnetsystems symmetrischen Magnetkreisen ausbildet. Da der Permanentmagnet 8 eine Permeabilität wie die von Luft hat, erzeugt er in dem Magnetkreis des Elektromagneten 1 einen relativ hohen magnetischen Widerstand, der durch erhöhte Ansteuerleistung der Erregerspule kompensiert werden muß. Zur Reduzierung des magnetischen Widerstandes macht man daher die Querschnittsfläche des Permanentmagneten 8 relativ groß, während sich die dadurch geringe mögliche Dicke des Permanentmagneten 8 aus der erforderlichen magnetischen Spannung und der möglichst großen Koerzitivfeldstärke ergibt. Wegen seiner größeren Fläche werden auch die Wirbelstromverluste in dem Permanentmagneten 8 größer. Dünne, große Permanentmagnete 8 sind bei ihrer Bearbeitung einer erheblichen Bruchgefahr ausgesetzt, was die Herstellungskosten beträchtlich erhöht. Zur Reduzierung der Wirbelstromverluste ist der Permanentmagnet 8 aus Kobalt-Samarium hergestellt, das relativ niederohmig ist, dafür allerdings sehr spröde, so daß die Bruchgefahr bei der Magnetbearbeitung noch weiter verstärkt wird. Wie bereits erwähnt, wird der freifliegende Anker 10 ausschließlich von dem auf das Ventilglied des Magnetventils wirkenden hydraulischen Gegendruck vom Magnetpol abgehoben. Der hydraulische Gegendruck nimmt während der Öffnungsphase des Magnetventils stark ab und wird teilweise sogar negativ. Daher wäre zum sicheren Offenhalten des Ventils eine umpolende Magnetkraft erwünscht. Auch bei Umkehrung des Magnetflusses im Anker 10 ist dies unmöglich, da die Magnetkraft proportional zu (φp - φE)² ist, also proportional zum Quadrat der Magnetflußdifferenz.The magnetic flux generated by the excitation coil 2 is denoted in FIG. 1 by φ E and the magnetic flux generated by the permanent magnet 8 by φ P. It can clearly be seen that the magnetic flux φ E is formed via armature 10, working air gap 11, magnetic core 3, yoke 5, magnet housing 4, permanent magnet 8 and pole plate 9 in two magnetic circuits symmetrical to the axis of the magnet system. Since the permanent magnet 8 has a permeability like that of air, it generates a relatively high magnetic resistance in the magnetic circuit of the electromagnet 1, which is increased by Driving power of the excitation coil must be compensated. In order to reduce the magnetic resistance, the cross-sectional area of the permanent magnet 8 is therefore made relatively large, while the thickness of the permanent magnet 8, which is thereby small, results from the required magnetic voltage and the greatest possible coercive field strength. Because of its larger area, the eddy current losses in the permanent magnet 8 also increase. Thin, large permanent magnets 8 are exposed to a considerable risk of breakage during their processing, which increases the manufacturing costs considerably. To reduce the eddy current losses, the permanent magnet 8 is made of cobalt samarium, which has a relatively low resistance, but is very brittle, so that the risk of breakage during magnet processing is further increased. As already mentioned, the free-flying armature 10 is lifted from the magnetic pole exclusively by the hydraulic back pressure acting on the valve member of the solenoid valve. The hydraulic back pressure decreases strongly during the opening phase of the solenoid valve and sometimes even becomes negative. A polarity reversing magnetic force would therefore be desirable to keep the valve open. Even when the magnetic flux in armature 10 is reversed, this is impossible because the magnetic force is proportional to (φ p - φ E ) ², that is to say proportional to the square of the magnetic flux difference.

Vorteile der ErfindungAdvantages of the invention

Das erfindungsgemäße Magnetsystem mit den kennzeichnenden Merkmalen des Anspruchs 1 hat den Vorteil, daß der Magnetkreis des Elektromagneten sich nunmehr über den Gegenpol, den zweiten Arbeitsluftspalt, den Anker, den ersten Arbeitsluftspalt, den Magnetkern, das Rückschlußjoch und das Magnetgehäuse schließt und damit der Permanentmagnet mit seinem großen magnetischen Widerstand nicht mehr im Magnetkreis des Elektromagneten liegt. Dadurch wird einerseits die Ansteuerleistung für den Elektromagneten geringer, insbesondere bei vom Permanentmagneten abgefallenen Anker, und andererseits eine größere Freiheit in der Dimensionierung des Permanentmagneten und in dessen Materialauswahl gewonnen. Der Permanentmagnet braucht nicht mehr nach dem Gesichtspunkt des minimierten magnetischen Widerstandes bemessen zu werden. Der Permanentmagnet kann damit dicker gemacht werden, so daß seine Bruchfestigkeit vergrößert wird. Als Magnetmaterial kann anstelle des bisher wegen seines geringen Temperaturkoeffizienten der Remanenz verwendeten Kobalt-Samarium jetzt auch Eisen-Neodym verwendet werden, das bei vergleichbarer magnetischer Energie etwa doppelt so hochohmig ist und wegen seines hohen Temperaturkoeffizienten der Remanenz bisher nicht in Betracht gezogen wurde. Eisen-Neodym ist nicht so spröde wie Kobalt-Samarium und läßt sich besser verarbeiten. Insgesamt läßt sich bei dem erfindungsgemäßen Magnetsystem der Permanentmagnet wesentlich kostengünstiger fertigen.The magnet system according to the invention with the characterizing features of claim 1 has the advantage that the magnetic circuit of the electromagnet now closes via the opposite pole, the second working air gap, the armature, the first working air gap, the magnetic core, the yoke and the magnet housing, and thus the permanent magnet its great magnetic resistance no longer in Magnetic circuit of the electromagnet is. On the one hand, this means that the drive power for the electromagnet is lower, in particular when the armature has dropped from the permanent magnet, and on the other hand greater freedom in the dimensioning of the permanent magnet and in its material selection is obtained. The permanent magnet no longer needs to be dimensioned from the point of view of the minimized magnetic resistance. The permanent magnet can thus be made thicker, so that its breaking strength is increased. Instead of the cobalt samarium previously used because of its low temperature coefficient of remanence, iron neodymium can now be used as a magnetic material, which is about twice as high-resistance with comparable magnetic energy and has not been considered so far because of its high temperature coefficient of remanence. Iron neodymium is not as brittle as cobalt samarium and is easier to process. Overall, the permanent magnet can be manufactured much more cost-effectively in the magnet system according to the invention.

Bei der konstruktiven Ausbildung des erfindungsgemäßen Magnetsystems mit Gegenpol und zweitem Arbeitsluftspalt wird mit Erregung des Elektromagneten auf den Anker eine Abhebekraft ausgeübt, die der Anzugskraft des Permanentmagneten entgegengerichtet ist. Wie Fig. 3 zeigt, nimmt die auf den Anker wirkende Anzugskraft von Permanentmagnet und Elektromagnet (bei konstantem Arbeitsluftspalt) mit zunehmender Erregung des Elektromagneten ab und wird schließlich negativ, so daß der Anker nicht nur vom Hydraulikdruck im Magnetventil vom Magnetpol abgezogen wird, sondern zusätzlich durch eine elektromagnetisch erzeugte Abhebekraft. Diese negative Magnetkraft ist bei der Verwendung des Magnetsystems in Hydraulikventilen, insbesondere Kraftstoffeinspritzventilen, erwünscht, da bei diesen der über das Ventilglied auf den Anker wirkende hydraulische Druck während des Öffnungshubs des Magnetsystems sehr klein wird und nicht mehr ausreichend ist, den Anker in einer definierten Endlage, in welcher das Magnetventil definiert geöffnet ist, zu halten. Diese "negative Anzugskraft" auf den Anker wird ohne Stromumkehr in der Erregerspule des Elektromagneten erzeugt, so daß ein Eingriff in die Steuerelektronik nicht erforderlich ist. Bei abgeschalteter Magneterregung wirkt auf den Anker eine maximale Anzugskraft Fmax. Mittels der magnetischen Spannung am Streuluftspalt zwischen Magnetgehäuse und Gegenpol kann der Arbeitsbereich zwischen Fmax-an und Fmin-an (an = angezogen) über die Durchflutung I·w, entsprechend der strichlinierten Linie in Fig. 3 parallel verschoben werden. Die in Fig. 3 punktiert gezeichnete Kennlinie für den abfallenden Anker kann ebenfalls längs der Durchflutung verschoben werden. Die Umschaltpunkte w·Ian,w·Iab, bei welchen die Anzugskraft F gleich der auf den Anker wirkenden Hydraulikkraft Fhydr ist, (bei Verwendung des Magnetsystems in einem hydraulischen Magnetventil)sind so einstellbar. Ohne magnetische Spannung am Streuluftspalt lägen sie außerhalb des gewünschten Bereichs.In the constructive design of the magnet system according to the invention with a counter pole and a second working air gap, a lifting force is exerted on the armature when the electromagnet is excited, which counteracts the attraction force of the permanent magnet. As shown in Fig. 3, the force acting on the armature of the permanent magnet and electromagnet (with a constant working air gap) decreases with increasing excitation of the electromagnet and finally becomes negative, so that the armature is not only removed from the magnetic pole by the hydraulic pressure in the solenoid valve, but additionally by an electromagnetically generated lifting force. This negative magnetic force is desirable when using the magnet system in hydraulic valves, in particular fuel injection valves, because in these the valve member acts on the valve member Hydraulic pressure acting on the armature becomes very small during the opening stroke of the magnet system and is no longer sufficient to hold the armature in a defined end position in which the solenoid valve is open in a defined manner. This "negative attraction force" on the armature is generated without reversal of current in the excitation coil of the electromagnet, so that an intervention in the control electronics is not necessary. When the magnet excitation is switched off, a maximum pulling force F max acts on the armature. By means of the magnetic voltage at the stray air gap between the magnet housing and the opposite pole, the working range between F max-an and F min-an (an = attracted) can be shifted in parallel via the flow I · w, corresponding to the dashed line in FIG. 3. The dotted curve in FIG. 3 for the falling anchor can also be shifted along the flow. The switchover points w · I on , w · I off , at which the tightening force F is equal to the hydraulic force F hydr acting on the armature (when using the magnet system in a hydraulic solenoid valve) can be set in this way. Without magnetic tension at the stray air gap, they would be outside the desired range.

Die Hysterese Ian - Iab der elektrischen Erregung des Elektromagneten, d.h. die zum Bewegen des Ankers aus den beiden Anschlagstellungen erforderliche Erregung des Elektromagneten, ist bei ansonst gleichen Daten um den Faktor √2 kleiner als bei dem bekannten Magnetsystem. Damit geht der zur Aussteuerung der Hysterese erforderliche Leistungsbedarf um die Hälfte zurück. Dies ermöglicht entweder eine Stromreduzierung und damit eine Reduktion der Wirbelstromverluste oder eine Reduktion der Windungszahl der Erregerspule und damit eine Verringerung deren Induktivität.The hysteresis I an - I from the electrical excitation of the electromagnet, ie the excitation of the electromagnet required to move the armature from the two stop positions, is smaller by a factor of √2 than in the known magnet system with otherwise identical data. This reduces the power required to control the hysteresis by half. This enables either a reduction in current and thus a reduction in eddy current losses or a reduction in the number of turns of the excitation coil and thus a reduction in its inductance.

Das erfindungsgemäße Magnetsystem zeichnet sich ferner durch eine ausreichend große Änderungsgeschwindigkeit der auf den Anker wirkenden Magnetkraft über den Erregerstrom aus. Damit reduziert sich der Einfluß von variablen Kräften Fhydr. an den Ankeranschlägen auf die Schaltzeit.The magnet system according to the invention is further characterized by a sufficiently large rate of change of the magnetic force acting on the armature via the excitation current. In order to the influence of variable forces F hydr is reduced. at the anchor stops on the switching time.

Durch die in den weiteren Ansprüchen aufgeführten Maßnahmen sind vorteilhafte Weiterbildungen und Verbesserungen der im Anspruch 1 angegebenen Schaltungsanordnung möglich.The measures listed in the further claims allow advantageous developments and improvements of the circuit arrangement specified in claim 1.

Bei einer vorteilhaften Ausführungsform der Erfindung ist die vom Rückschlußjoch abgekehrte Stirnseite des Magnetgehäuses über einen vorzugsweise damit einstückigen Ringsteg mit dem Magnetkern nahe dessen Polfläche verbunden. Der Permanentmagnet liegt auf dem Ringsteg auf und wird lediglich durch seine Magnetkraft an diesem gehalten. Im Ringsteg ist eine in Radialrichtung wirkende magnetische Engstelle eingebracht. Durch entsprechende Ausbildung dieser Engstelle kann die Aussteuerung des Magnetflusses im Magnetkern optimal eingestellt werden. Durch gezielte Sättigung der magnetischen Engstelle läßt sich außerdem verhindern, daß kein Streufluß des Elektromagneten über die Engstelle fließt.In an advantageous embodiment of the invention, the end face of the magnet housing facing away from the yoke is connected to the magnet core near the pole face thereof via an annular web, preferably integral therewith. The permanent magnet rests on the ring web and is held on it only by its magnetic force. A magnetic constriction acting in the radial direction is introduced into the ring web. By appropriately designing this constriction, the modulation of the magnetic flux in the magnetic core can be optimally adjusted. Through targeted saturation of the magnetic constriction, it can also be prevented that no stray flux from the electromagnet flows over the constriction.

Gemäß einer bevorzugten Ausführungsform der Erfindung ist der Gegenpol mit Flußleitelement durch eine Polplatte realisiert, die mittels eines Halters am Magnetgehäuse befestigt ist. Der Halter besteht aus unmagnetischem Material oder aus weichmagnetischem Material, z.B. Nickel-Eisen, mit einer Curie-Temperatur von ca. 80°C. Das weichmagnetische Material wird dann verwendet, wenn der Permanentmagnet aus Eisen-Neodym hergestellt wird, um den hohen Temperaturgang des aus Eisen-Neodym gefertigten Permanentmagneten mit dem großen Temperaturgang der niedrig liegenden Sättigungsinduktion des Nickel-Eisen exakt zu kompensieren.According to a preferred embodiment of the invention, the opposite pole with flux guide element is realized by a pole plate which is fastened to the magnet housing by means of a holder. The holder is made of non-magnetic material or of soft magnetic material, eg nickel iron, with a Curie temperature of approx. 80 ° C. The soft magnetic material is used when the permanent magnet is made of iron neodymium in order to exactly compensate for the high temperature response of the permanent magnet made of iron neodymium with the large temperature response of the low-lying saturation induction of the nickel-iron.

Zeichnungdrawing

Die Erfindung ist anhand von in der Zeichnung dargestellten Ausführungsbeispielen in der nachfolgenden Beschreibung näher erläutert. Es zeigen:

Fig. 1
einen schematischen Längsschnitt eines Magnetsystems gemäß dem Stand der Technik,
Fig. 2
einen schematischen Längsschnitt des erfindungsgemäßen Magnetsystems,
Fig. 3
Diagramme der Magnetkraft des Magnetsystems in Fig. 2 über den Strom in der Erregerspule,
Fig. 4
einen Längsschnitt eines Kraftstoffeinspritzventils, mit integrierten Magnetsystem gemäß Fig. 2,
Fig. 5
eine Detaildarstellung eines Ausschnitts des Kraftstoffeinspritzventils in Fig. 4.
The invention is explained in more detail in the following description with reference to exemplary embodiments shown in the drawing. Show it:
Fig. 1
2 shows a schematic longitudinal section of a magnet system according to the prior art,
Fig. 2
2 shows a schematic longitudinal section of the magnet system according to the invention,
Fig. 3
Diagrams of the magnetic force of the magnet system in FIG. 2 over the current in the excitation coil,
Fig. 4
3 shows a longitudinal section of a fuel injection valve with an integrated magnet system according to FIG. 2,
Fig. 5
4 shows a detailed illustration of a section of the fuel injection valve in FIG. 4.

Beschreibung der AusführungsbeispieleDescription of the embodiments

In Fig. 2 ist schematisch ein Längsschnitt eines Magnetsystems für Magnetventile zur Steuerung von Flüssigkeiten dargestellt, der den prinzipiellen Aufbau des Magnetsystems verdeutlicht. Das Magnetsystem besteht aus einem Elektromagneten 20 und aus einem Permanentmagneten 21. Der Elektromagnet 20 weist in bekannter Weise eine Erregerspule 38 auf, die einen einen Magnetpol 22 mit Polfläche 23 bildenden Magnetkern 24 ringförmig umgibt und ihrerseits von einem Magnetgehäuse 25 umschlossen ist. Das Magnetgehäuse 25 ist einerseits über ein Rückschlußjoch 26 mit der von der Polfläche 23 abgekehrten Stirnseite des Magnetkerns 24 und andererseits über einen Ringsteg 27 nahe der Polfläche 23 mit dem Magnetkern 24 verbunden. Magnetkern 24, Magnetgehäue 25, Rückschlußjoch 26 und Ringsteg 27 bestehen aus dem gleichen ferromagnetischen Material. Der ringförmige Permanentmagnet 21 liegt auf dem Ringsteg 27 auf und umschließt den Magnetkern 24. Er wird am Ringsteg 27 ausschließlich durch seine Magnetkraft gehalten und überdeckt nur einen Teil der Fläche des Ringstegs 27. Der Permanentmagnet kann aus Eisen-Neodym hergestellt sein.2 schematically shows a longitudinal section of a magnet system for solenoid valves for controlling liquids, which illustrates the basic structure of the magnet system. The magnet system consists of an electromagnet 20 and a permanent magnet 21. In a known manner, the electromagnet 20 has an excitation coil 38 which surrounds a magnetic core 24 which forms a magnetic pole 22 with a pole face 23 and is in turn enclosed by a magnet housing 25. The magnet housing 25 is close on the one hand via a yoke 26 with the end face of the magnetic core 24 facing away from the pole face 23 and on the other hand via an annular web 27 the pole face 23 connected to the magnetic core 24. Magnetic core 24, magnetic housing 25, yoke 26 and ring web 27 are made of the same ferromagnetic material. The ring-shaped permanent magnet 21 lies on the ring web 27 and surrounds the magnetic core 24. It is held on the ring web 27 exclusively by its magnetic force and covers only part of the surface of the ring web 27. The permanent magnet can be made of iron neodymium.

Dem Magnetpol 22 liegt ein scheibenförmiger Anker 28 unter Ausbildung eines ersten Arbeitsluftspaltes 31 freifliegend gegenüber und überdeckt einen Teilbereich des Permanentmagneten 21 unter Ausbildung eines größeren Ringluftspaltes 33. Auf der vom Arbeitsluftspalt 31 abgekehrten Seite des Ankers 28 liegt ein magnetischer Gegenpol 29, dessen Polfläche 30 zum Anker 28 einen zweiten Arbeitsluftspalt 32 ausbildet. Der Gegenpol 29 mit seiner ringförmigen Polfläche 30 ist auf einer Polplatte 35 ausgebildet, die mit einem Randsteg 36 den Permanentmagneten 21 umgreift und über einen ringförmigen Streuluftspalt 34 an dem Ringsteg 27 und damit am Magnetgehäuse 25 angekoppelt ist. Die Polplatte 35 ist mit einem Halteelement 37 an dem Magnetgehäuse 25 befestigt und weist eine kreisförmige Ausnehmung zum Durchtritt eines mit dem Anker 28 zu verbindendes Ventilglieds auf. Das Halteelement 37 besteht entweder aus unmagnetischem Material oder aus weichmagnetischem Material mit einer Curie-Temperatur von ca. 80°C. Ein solches Beispiel für ein weichmagnetisches Material ist Nickel-Eisen. Letzteres wird bevorzugt dann verwendet, wenn der Permanentmagnet 21 aus Eisen-Neodym hergestellt ist. Mit dem großen Temperaturgang der niedrig liegenden Sättigungsinduktion des Nickel-Eisens kann der hohe Temperaturgang des Permanentmagneten 21 aus Eisen-Neodym exakt kompensiert werden. Die durch eingetragene Symbole charakterisierte Durchflutung der Erregerspule 38 des Elektromagneten 20 und die Anordnung des in Axialrichtung magnetisierten Permamentmagneten 21 ist so getroffen, daß die Magnetflüsse φE und φP von Elektromagnet 20 und Permanentmagnet 21 im Arbeitsluftspalt 31 einander entgegengerichtet sind. Die beiden Magnetflüsse bilden sich symmetrisch zur Achse des Magnetsystems aus. Der Übersichtlichkeit halber ist in Fig. 2 der jeweilige Magnetfluß nur in einer Symmetriehälfte dargestellt. Der Magnetfluß φP des Permanentmagneten 21 teilt sich in zwei Teilflüsse φP1 und φP2 auf. Ein Streufluß φP3 bildet sich über den Streuluftspalt 34 aus. φp2 geht in dem den Anker 28 überragenden Bereich 67 des Permanentmagneten 21 nicht über den Anker 21 und dient der magnetischen Vorspannung des Streuluftspaltes 34.A magnetic armature 28 is exposed to the magnetic pole 22 with the formation of a first working air gap 31 and covers a partial area of the permanent magnet 21 with the formation of a larger ring air gap 33 Armature 28 forms a second working air gap 32. The opposite pole 29 with its annular pole face 30 is formed on a pole plate 35 which surrounds the permanent magnet 21 with an edge web 36 and is coupled to the ring web 27 and thus to the magnet housing 25 via an annular stray air gap 34. The pole plate 35 is fastened to the magnet housing 25 with a holding element 37 and has a circular recess for the passage of a valve member to be connected to the armature 28. The holding element 37 consists either of non-magnetic material or of soft magnetic material with a Curie temperature of approximately 80 ° C. One such example of a soft magnetic material is nickel iron. The latter is preferably used when the permanent magnet 21 is made of iron neodymium. With the large temperature response of the low-lying saturation induction of nickel iron, the high temperature response of the permanent magnet 21 made of iron neodymium can be exactly compensated for. The flooding of the Excitation coil 38 of the electromagnet 20 and the arrangement of the permanent magnet 21 magnetized in the axial direction is such that the magnetic fluxes φ E and φ P from the electromagnet 20 and the permanent magnet 21 in the working air gap 31 are directed in opposite directions. The two magnetic fluxes are formed symmetrically to the axis of the magnet system. For the sake of clarity, the respective magnetic flux is shown in FIG. 2 only in one half of the symmetry. The magnetic flux φ P of the permanent magnet 21 is divided into two partial fluxes φ P1 and φ P2 . A leakage flux φ P3 forms over the leakage air gap 34. φ p2 does not pass over armature 21 in region 67 of permanent magnet 21 projecting armature 28 and serves to bias the stray air gap 34 magnetically.

In dem Ringsteg 27 ist durch Einbringen einer Ringnut 39 eine magnetische Engstelle 40 ausgebildet. Diese Engstelle 40 reduziert den Teilfluß φP2 auf einen Wert, der für die Aussteuerung des Flusses im Magnetkern 24 in beiden Richtungen optimal ist. Außerdem kann die Engstelle 40 gezielt gesättigt werden, so daß verhindert wird, daß ein Streufluß von φE über diesen Pfad fließt. Die Bewegung des Ankers 28 ist durch hier nicht dargestellte Anschläge begrenzt, so daß jeweils ein Restluftspalt zwischen den Polflächen 23 bzw. 30 und dem am Anschlag liegenden Anker verbleibt. Der Ringluftspalt 33 ist etwa doppelt so groß bemessen wie der maximale Arbeitsluftspalt 31 bzw. der maximale Arbeitsluftspalt 32, der dem maximalen Hub des Ankers 28 entspricht. Die ringförmige Querschnittsfläche des Permanentmagneten 21 ist dabei etwa 1,5 mal größer gemacht als die Summe der Polflächen 23,30 von Magnetpol 22 und Gegenpol 29.A magnetic constriction 40 is formed in the annular web 27 by introducing an annular groove 39. This constriction 40 reduces the partial flux φ P2 to a value which is optimal for controlling the flux in the magnetic core 24 in both directions. In addition, the constriction 40 can be specifically saturated, so that a leakage flux of φ E is prevented from flowing along this path. The movement of the armature 28 is limited by stops, not shown here, so that a residual air gap remains between the pole faces 23 and 30 and the armature lying against the stop. The ring air gap 33 is dimensioned approximately twice as large as the maximum working air gap 31 or the maximum working air gap 32, which corresponds to the maximum stroke of the armature 28. The annular cross-sectional area of the permanent magnet 21 is made about 1.5 times larger than the sum of the pole areas 23, 30 of the magnetic pole 22 and the opposite pole 29.

Die Kraft F, die auf den Anker 28 nach oben, d.h. zum Magnetpol 22 hin, wirkt, ist in Fig. 3 in Abhängigkeit von der Durchflutung ϑ für die beiden Anschlagstellungen des Ankers (an = angezogen; ab = abgefallen) dargestellt. Ist die Durchflutung ϑ der Erregerspule 38 Null, so wird der Anker 28 mit maximalen Kräften Fmax-an,Fmax-ab beaufschlagt, die ausschließlich vom Permanentmagneten 21 erzeugt werden. Mit zunehmender Durchflutung ϑ der Erregerspule 38 oder durch Veränderung des Streuluftspaltes 34 wird der Magnetfluß des Permanentmagneten 21 im Arbeitsluftspalt 31 geschwächt. Zugleich wird im Arbeitsluftspalt 32 eine den Anker 28 in Gegenrichtung beaufschlagende Gegenkraft erzeugt. Die auf den Anker 28 nach oben wirkende Kraft nimmt gemäß Fig. 3 ab und wird schließlich negativ.The force F, which acts on the armature 28 upwards, ie towards the magnetic pole 22, is in FIG. 3 as a function of the flow ϑ for the two stop positions of the Anchor (on = attracted; from = fallen off) is shown. If the flow ϑ of the excitation coil 38 is zero, the armature 28 is subjected to maximum forces F max-an , F max-ab , which are generated exclusively by the permanent magnet 21. With increasing flow ϑ of excitation coil 38 or by changing the stray air gap 34, the magnetic flux of the permanent magnet 21 in the working air gap 31 is weakened. At the same time, a counterforce acting on the armature 28 in the opposite direction is generated in the working air gap 32. The force acting upward on the armature 28 decreases according to FIG. 3 and finally becomes negative.

In Fig. 4 ist im Längsschnitt ein Kraftstoffeinspritzventil dargestellt, in dem das beschriebene Magnetsystem eingesetzt ist. Soweit Bauteile mit denen in Fig. 2 übereinstimmen, sind sie mit gleichen Bezugszeichen versehen. Das Magnetsystem ist in einem Siebgehäuse 41 eingesetzt, in dem ein Kraftstoffzufluß 42 und ein Kraftstoffabfluß 43 vorgesehen sind. Kraftstoffzufluß 42 und Kraftstoffabfluß 43 sind durch ein eingespritztes Filter oder Sieb 44 von axialen Axialkanälen 45,66 getrennt, die sich bis zur Polplatte 35 des Magnetsystems erstrecken. Zwischen den Axialkanälen 45,66 sind eine Mehrzahl von Kraftstoffleitstücken 55 eingesetzt (Fig. 5). Die Polplatte 35 schließt das Siebgehäuse 41 stirnseitig ab und ist mit unmagnetischen bzw. temperaturabhängig magnetisch gesättigten Anschlußstücken 46, die dem Halteelement 37 in Fig. 2 entsprechen, an dem Magnetgehäuse 25 angeschweißt. Durch die kreisförmige Aussparung 47 der Polplatte 35 tritt ein Ventilkörper 48 hindurch, der fest mit dem Anker 28 verbunden ist. Konzentrisch zu der Aussparung 47 trägt die Polplatte 35 auf der von dem Anker 28 abgekehrten Seite eine Aussparung 49, an welcher ein Ventilsitz 50 ausgebildet ist, mit dem der Ventilkörper 48 zum Schließen und Öffnen des Kraftstoffeinspritzventils zusammenwirkt. Oberhalb des Ventilsitzes 50 trägt der Ventilkörper 48 eine Umlaufnut 51, die über in der Polplatte 35 im Bereich der Durchtrittsöffnung 47 angeordnete Radialschlitze 52 mit einem den Anker 28 kreisförmig umgebenden Strömungsspalt 53 in Verbindung steht, der seinerseits über Kanäle 56 mit den Axialkanälen 66 in Verbindung steht. Die Kraftstoffströmung in Kanälen 54 zwischen den Axialkanälen 45 und 66 soll vorzugsweise die Polplatte 35 kühlen. Die Kraftstoffströmung im Strömungsspalt 53 kühlt den vorderen Bereich des Ventils. Bei Heißstart kann sich der flüssige Teil des Kraftstoffs unterhalb der Kanäle 54 in dem Raum 56 (Fig. 4) sammeln und von den gasförmigen Komponenten so trennen, daß nur flüssiger Kraftstoff eingespritzt wird.In Fig. 4, a fuel injection valve is shown in longitudinal section, in which the described magnet system is used. As far as components correspond to those in Fig. 2, they are provided with the same reference numerals. The magnet system is inserted in a screen housing 41 in which a fuel inflow 42 and a fuel outflow 43 are provided. Fuel inflow 42 and fuel outflow 43 are separated by an injected filter or strainer 44 from axial axial channels 45, 66, which extend to the pole plate 35 of the magnet system. A plurality of fuel guide pieces 55 are inserted between the axial channels 45, 66 (FIG. 5). The pole plate 35 closes the screen housing 41 on the end face and is welded to the magnet housing 25 with non-magnetic or temperature-dependent magnetically saturated connecting pieces 46, which correspond to the holding element 37 in FIG. 2. A valve body 48 passes through the circular recess 47 of the pole plate 35 and is fixedly connected to the armature 28. Concentric to the recess 47, the pole plate 35 carries on the side facing away from the armature 28 a recess 49, on which a valve seat 50 is formed, with which the valve body 48 cooperates to close and open the fuel injection valve. Above the Valve seat 50, the valve body 48 carries a circumferential groove 51, which is connected via radial slots 52 arranged in the pole plate 35 in the region of the passage opening 47 to a flow gap 53 which surrounds the armature 28 in a circular manner and which in turn is connected to the axial channels 66 via channels 56. The fuel flow in channels 54 between the axial channels 45 and 66 should preferably cool the pole plate 35. The fuel flow in the flow gap 53 cools the front area of the valve. In the event of a hot start, the liquid part of the fuel can collect below the channels 54 in the space 56 (FIG. 4) and separate from the gaseous components in such a way that only liquid fuel is injected.

Die Bereiche 57 des Siebgehäuses 41 sind federnd ausgebildet, so daß sich das Siebgehäuse 41 unabhängig von der Größe eines O-Rings 58 gegen einen Anschlag 59 an der Polplatte 35 anpreßt. Die Erregerwicklung 38 des Elektromagneten 20 wird von einem Spulenkörper 60 getragen und ist mit Anschlußstiften 61 verbunden. Diese wiederum sind mit Steckerstiften 62 in einem Steckergehäuse 63 verschweißt. Das Steckergehäuse 63 ist mit dem Magnetgehäuse 25 durch eine Umbördelung 64 fest verbunden. Der Magnetkern 24 mit daran einstückig befestigtem Rückschlußjoch 26 und Erregerspule 38 sind im Magnetgehäuse 25 durch eine Vergußmasse 65 vergossen.The areas 57 of the screen housing 41 are resilient, so that the screen housing 41 presses against a stop 59 on the pole plate 35 regardless of the size of an O-ring 58. The excitation winding 38 of the electromagnet 20 is carried by a coil former 60 and is connected to connection pins 61. These in turn are welded to connector pins 62 in a connector housing 63. The connector housing 63 is firmly connected to the magnet housing 25 by a flange 64. The magnetic core 24 with an integrally attached yoke 26 and excitation coil 38 are encapsulated in the magnet housing 25 by a potting compound 65.

Claims (12)

  1. Magnetic system for solenoid valves for controlling liquids, in particular for fuel-injection valves, having an electromagnet (20) which has a magnet core (24) forming a magnet pole (22), a field coil (38) surrounding the magnet core (24), and a magnet housing (25) which is coaxial therewith and surrounds the field coil and is connected as a magnetic return path via a yoke (26) to the end face of the magnet core (24) which is averted from the pole face (23), having an annular permanent magnet (21), which has an axial direction of magnetization and is arranged coaxially with the magnet core (24) near the pole surface (23) thereof, and having an approximately disc-shaped armature (28) which is situated opposite the magnet pole (22) in a self-supporting fashion with the formation of a working air gap relative to the pole face (23) thereof, the magnetomotive force of the field coil (38) and the arrangement of the permanent magnet (21) being such that the magnetic fluxes of the electromagnet and permanent magnet are directed opposite to one another in the working air gap, characterized in that a magnetic antipole (29), which is coupled to the magnet housing (25) via a flux concentrating element (35) embracing the permanent magnet (21) is arranged on the side of the armature (28) averted from the working air gap (31) with the formation of a second working air gap (32) between the pole face (30) of said antipole and the armature (28).
  2. Magnetic system according to Claim 1, characterized in that the coupling of the antipole (29) to the flux concentrating element (35) is undertaken on the magnet housing (25) via a dispersion air gap (34).
  3. Magnetic system according to Claim 1 or 2, characterized in that the end face of the magnet housing (25) averted from the yoke (26) is connected to the magnet core (24) near the pole face (30) thereof via a preferably one-piece annular web (27), in that the permanent magnet (21) rests on the annular web (27), and in that the annular web (27) has a constriction (40) acting in the radial direction.
  4. Magnetic system according to Claim 3, characterized in that the magnetic constriction (40) is constructed such that it is magnetically saturated or very quickly reaches this saturation state upon application of an electric field current to the field coil (38).
  5. Magnetic system according to Claim 3 or 4, characterized in that the magnetic constriction (40) is implemented by an annular groove (39) introduced into the annular web (27).
  6. Magnetic system according to one of Claims 3-5, characterized in that the antipole (29) with flux concentrating element is constructed as a one-piece pole plate (35) which embraces the permanent magnet (21) with a radial clearance and bears against the annular web (27) and/or magnet housing (25).
  7. Magnetic system according to Claim 6, characterized in that there is constructed between the pole plate (35) and the annular web (27) or the magnet housing (25) a dispersion air gap (34) which is magnetically biased by means of a magnetic flux which is tapped at the permanent magnet (21) in the region (67) thereof overlapping the armature (28).
  8. Magnetic system according to Claim 6 or 7, characterized in that the pole plate (35) has a concentric passage opening (47) for a valve member (48) of the solenoid valve which is permanently connected to the armature (28).
  9. Magnetic system according to one of Claims 6-8, characterized in that the pole plate (35) is fastened to the magnet housing (25) via a holder (37), and in that the holder (37) consists of non-magnetic material or of magnetically soft material with a Curie temperature of 80°C, for example iron-nickel.
  10. Magnetic system according to one of Claims 1-9, characterized in that the annular cross-sectional area of the permanent magnet which is situated parallel to the pole face (23) of the magnet pole (22) opposite the armature (28) is approximately 1.5 times larger than the sum of the pole faces (23, 30) of the magnet pole (22) and antipole (29).
  11. Magnetic system according to one of Claims 1-10, characterized in that the permanent magnet (21) is produced from iron-neodymium.
  12. Magnetic system according to one of Claims 1-11, characterized in that the armature (28) at least partially overlaps the permanent magnet (21) with the formation of an annular gap (33), and the permanent magnet (21) is set back so far relative to the pole face (23) of the magnet pole (22) that in the case of the minimum working air gap (31) between the armature (28) and the pole face (23) of the magnet pole (22), the annular air gap (33) between the armature (28) and permanent magnet (21) corresponds to the maximum stroke of the armature (28).
EP91111897A 1990-07-28 1991-07-17 Magnet system Expired - Lifetime EP0469385B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE4024054A DE4024054A1 (en) 1990-07-28 1990-07-28 MAGNETIC SYSTEM
DE4024054 1990-07-28

Publications (2)

Publication Number Publication Date
EP0469385A1 EP0469385A1 (en) 1992-02-05
EP0469385B1 true EP0469385B1 (en) 1994-10-05

Family

ID=6411229

Family Applications (1)

Application Number Title Priority Date Filing Date
EP91111897A Expired - Lifetime EP0469385B1 (en) 1990-07-28 1991-07-17 Magnet system

Country Status (6)

Country Link
US (1) US5161779A (en)
EP (1) EP0469385B1 (en)
JP (1) JP3107855B2 (en)
BR (1) BR9103216A (en)
CZ (1) CZ279794B6 (en)
DE (2) DE4024054A1 (en)

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Also Published As

Publication number Publication date
DE59103162D1 (en) 1994-11-10
JPH04254306A (en) 1992-09-09
JP3107855B2 (en) 2000-11-13
DE4024054A1 (en) 1992-01-30
CS229791A3 (en) 1992-02-19
CZ279794B6 (en) 1995-06-14
BR9103216A (en) 1992-02-18
US5161779A (en) 1992-11-10
EP0469385A1 (en) 1992-02-05

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