EP2756194A1 - Gear pump and method for producing a gear pump - Google Patents

Gear pump and method for producing a gear pump

Info

Publication number
EP2756194A1
EP2756194A1 EP12735309.2A EP12735309A EP2756194A1 EP 2756194 A1 EP2756194 A1 EP 2756194A1 EP 12735309 A EP12735309 A EP 12735309A EP 2756194 A1 EP2756194 A1 EP 2756194A1
Authority
EP
European Patent Office
Prior art keywords
gear
magnets
gear pump
toothed ring
mim
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.)
Withdrawn
Application number
EP12735309.2A
Other languages
German (de)
French (fr)
Inventor
Josef Frank
Alexander Fuchs
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Robert Bosch GmbH
Original Assignee
Robert Bosch GmbH
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Robert Bosch GmbH filed Critical Robert Bosch GmbH
Publication of EP2756194A1 publication Critical patent/EP2756194A1/en
Withdrawn legal-status Critical Current

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C11/00—Combinations of two or more machines or pumps, each being of rotary-piston or oscillating-piston type; Pumping installations
    • F04C11/008—Enclosed motor pump units
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C15/00—Component parts, details or accessories of machines, pumps or pumping installations, not provided for in groups F04C2/00 - F04C14/00
    • F04C15/0057—Driving elements, brakes, couplings, transmission specially adapted for machines or pumps
    • F04C15/008—Prime movers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C2/00—Rotary-piston machines or pumps
    • F04C2/08—Rotary-piston machines or pumps of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing
    • F04C2/10—Rotary-piston machines or pumps of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of internal-axis type with the outer member having more teeth or tooth-equivalents, e.g. rollers, than the inner member
    • F04C2/102—Rotary-piston machines or pumps of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of internal-axis type with the outer member having more teeth or tooth-equivalents, e.g. rollers, than the inner member the two members rotating simultaneously around their respective axes
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C2230/00—Manufacture
    • F04C2230/20—Manufacture essentially without removing material
    • F04C2230/21—Manufacture essentially without removing material by casting
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C2240/00—Components
    • F04C2240/40—Electric motor

Definitions

  • the present invention relates to a gear pump according to the preamble of claim 1 and a method of manufacturing a gear pump according to the preamble of claim 6.
  • Housing are arranged.
  • the gear pump includes a first gear and a second gear. Between the two gears, a delivery chamber is formed. The second gear is stored in its center on a thorn.
  • the first gear is an external gear and forms the rotor, the second gear is an internal gear, which is entrained in the eccentric center of the first gear.
  • the first gear comprises glued-in permanent magnets, which are arranged distributed over the circumference. External magnetic field generators generate a rotating, rotating field which causes direct motor following of the rotor.
  • Variants which comprise coating the magnets with nickel or Ni-Cu-Ni.
  • a permanent protection of the magnets from contact with fuel is not possible.
  • Another variant known from the prior art provides magnets not made of NdFeB but of iron ferrite, which withstands contact with fuel.
  • such magnets are only weakly magnetic, so they are not suitable for use in an electric gear pump.
  • a gear pump for conveying a fluid
  • Medium in particular for conveying fuel in a fuel injection system, which has a pump unit and a drive unit, which are arranged together in a housing, wherein the drive unit comprises a motor having a plurality of windings, which can be acted upon by current to a circulating Magnetic field to produce, and wherein the pump unit has a rotatably mounted externally toothed gear and an internally toothed ring, which are mounted eccentrically to each other, together form a toothing and are in meshing engagement to produce a conveying action, said acting as a rotor internally toothed toothed ring with a Variety of magnets is provided, wherein each of the plurality of magnets is embedded in the internal toothed ring and completely surrounded by the material of the internal toothed ring.
  • the magnets By fully embedding the magnets in the material of the internally toothed ring, the magnets are protected from the action of fuel, as this can not penetrate into the interior of the ring gear. Oxidation of the magnets by fuel is thereby prevented and the magnets retain their magnetic properties over a long period of time.
  • the internal toothed ring is produced by means of an MIM (Metal Injection Molding) method.
  • MIM Metal Injection Molding
  • the material of the internal toothed ring is steel.
  • the magnets are made of NdFeB (Neodymeisenbor). These magnets are particularly strong and therefore well suited for use in an electric gear pump.
  • the gear pump is designed as an internal gear pump.
  • a method of manufacturing a gear pump comprising a step of manufacturing a rotor-toothed ring gear by a MIM (Metal Injection Molten) method comprising the steps of positioning a plurality magnets in a MIM tool by means of a plurality of retraction cores withdrawn from a cavity formed by the MIM tool during the MIM process; and performing the MIM method of forming the internal toothed ring.
  • MIM Metal Injection Molten
  • the internally toothed toothed ring formed by means of the MIM method, in which a plurality of magnets are completely embedded is reworked by means of a machining step.
  • the internally toothed ring should preferably not have any open-pore porosity after machining in order to provide a particularly effective protection for the magnets embedded therein against corrosive actions.
  • the plurality of magnets embedded in the internal toothed ring are subsequently magnetized after the end of the MIM process, in particular after the machining step.
  • FIG. 1 shows an electric gear pump in exploded parts according to an embodiment.
  • Fig. 2 shows the core components of the gear pump shown in Fig. 1;
  • Fig. 3 is a half section through an internally toothed ring gear pump according to one embodiment.
  • an electric gear pump 1 is shown in exploded parts according to the prior art.
  • the electric gear pump 1 shown here is of the so-called “integrated design", in which the drive unit 2, which here includes the stator 3 with the windings 4 (see FIG. 2) and with a plug 16, and the pump unit 5, which here acting as a rotor internal gear ring 6 and the externally toothed gear
  • pinion 7 are formed as a non-separable unit, so that they can be arranged together in a housing 8.
  • the housing 8 is by means of a cover 9, in which also a suction-side inlet channel 10 and a pressure-side drain channel, which are respectively designed as inflow and drain kidney, and a thrust bearing 12, on which the externally toothed gear 7 is mounted, are provided closed.
  • the lid 9 is formed with a plurality of ribs 13.
  • a multiplicity of magnets 14, six pieces in the embodiment are provided on the internal toothed ring 6 acting as a rotor, which are fixed therein by means of gluing in recesses provided thereon on the rotor.
  • FIG. 2 shows the core components of the gear pump 1 shown in FIG. 1 without the surrounding housing 8.
  • the internally toothed toothed ring 6 and the externally toothed gear 7 together form a toothing 18 in which a multiplicity of delivery chambers 15 are formed.
  • the externally toothed gear 3 is arranged eccentrically to the internal toothed ring 2 rotatably on the axial bearing 12 shown in FIG. Wrd the externally toothed gear 3 is set in a rotational movement, so meshes with the external teeth of the externally toothed gear 3 in the internal toothing of the internally toothed ring 2 and generates a delivery volume flow of the fluid in which the toothing 18 runs.
  • the coils 4 are supplied with current such that a circulating magnetic field is generated.
  • the magnets 14, which are integrated into the rotor by means of adhesion are exposed on a surface 17 of the internally toothed ring 6, so that fuel flowing through the gear pump 1 oxidises the magnets 14 and deteriorates their magnetic action can.
  • Fig. 3 shows a half section through an acting as a rotor internal gear ring 6 of a gear pump 1, which forms the teeth 18 with an externally toothed gear 7, according to one embodiment.
  • the magnets 14 are completely embedded in the material of the internal toothed ring 6, which has been made of steel by means of a MIM (Metal Injection Molding) method. Since the internal gear ring 6 completely surrounds the magnets 14, it is not possible for the fuel that is pumped through the gear pump 1 to contact the magnets 14 and oxidize by the contact. Strong magnets, for example from NdFeb, which need not be additionally coated.
  • the internally toothed ring gear 6 provides a durable and effective protection for the magnets completely embedded therein.
  • the magnets 14 are inserted into a corresponding shape prior to the MIM process.
  • the magnets 14 are thereby positioned by so-called “retraction cores", which are withdrawn again from the cavity formed by the mold during the MIM process in order to allow the magnets 14 to be completely surrounded by the material of the internally toothed ring 6 or rotor to be formed Since the MIM process could possibly be adversely affected by already magnetized magnets 14 and because of the high process temperatures, the magnets 14 would be demagnetized anyway, the magnets 14 are subjected to a subsequent process, which involves a subsequent machining of the internal toothed ring 6 to be formed, magnetized.
  • the internal toothed ring 6 thus produced provides effective and lasting protection for the magnets 14, so that the gear pump 1 according to the invention operates optimally over a long period of time.

Abstract

The invention relates to a gear pump for conveying a fluid medium, more particularly for conveying fuel in a fuel injection system, which has a pump unit and a drive unit arranged together in one housing unit, wherein the drive unit comprises a motor with a plurality of windings, which can be energised with current in order to produce a revolving magnetic field, and wherein the pump unit has a rotatably mounted, externally toothed gear wheel and an internally toothed gear ring, which are mounted eccentrically to one another, together form a tooth system and maintain a mesh engagement to generate a conveying action, wherein the internally toothed gear ring acting as a rotor is provided with a plurality of magnets, wherein each of the plurality of magnets is embedded in the internally toothed gear ring and completely surrounded by the material of the internally toothed gear ring. The invention also relates to a method for producing such a gear pump.

Description

Beschreibung  description
Titel title
Zahnradpumpe und Verfahren zum Herstellen einer Zahnradpumpe Die vorliegende Erfindung betrifft eine Zahnradpumpe gemäß dem Oberbegriff des Anspruchs 1 und ein Verfahren zum Herstellen einer Zahnradpumpe gemäß dem Oberbegriff des Anspruchs 6.  The present invention relates to a gear pump according to the preamble of claim 1 and a method of manufacturing a gear pump according to the preamble of claim 6.
Stand der Technik State of the art
Als elektrische Förderpumpen zum Fördern von Kraftstoff in einem Kraftstoffeinspritzsystem, wie beispielsweise in einem Common Rail System, werden unter anderem Innenzahnradpumpen, Außenzahnradpumpen und Flügelzellenpumpen mit sogenannter integrierter Bauform eingesetzt, bei welcher die Förder- und An- triebseinheiten eine nicht trennbare Einheit bilden, welche gemeinsam in einemAs electrical feed pumps for conveying fuel in a fuel injection system, such as in a common rail system, inter alia, internal gear pumps, external gear pumps and vane pumps are used with so-called integrated design, in which the conveyor and drive units form a non-separable unit, which together in one
Gehäuse angeordnet sind. Housing are arranged.
In DE 10 2006 007 554 A1 ist eine elektrische Zahnradpumpe beschrieben, welche in einen Elektromotor integriert ist. Die Zahnradpumpe umfasst ein erstes Zahnrad und ein zweites Zahnrad. Zwischen den beiden Zahnrädern bildet sich ein Förderraum aus. Das zweite Zahnrad lagert in seiner Mitte auf einem Dorn. Das erste Zahnrad ist ein Außenzahnrad und bildet den Rotor, das zweite Zahnrad ist ein Innenzahnrad, welches im außermittigen Zentrum des ersten Zahnrads mitgeschleppt wird. Das erste Zahnrad umfasst eingeklebte Permanent- magnete, die über den Umfang verteilt angeordnet sind. Äußere Magnetfelderzeuger erzeugen ein umlaufendes, sich rotatorisch änderndes Feld, welches das direkte motorische Folgen des Rotors hervorruft. DE 10 2006 007 554 A1 describes an electric gear pump which is integrated in an electric motor. The gear pump includes a first gear and a second gear. Between the two gears, a delivery chamber is formed. The second gear is stored in its center on a thorn. The first gear is an external gear and forms the rotor, the second gear is an internal gear, which is entrained in the eccentric center of the first gear. The first gear comprises glued-in permanent magnets, which are arranged distributed over the circumference. External magnetic field generators generate a rotating, rotating field which causes direct motor following of the rotor.
Die im Stand der Technik bekannten elektrischen Zahnradpumpen mit integrierter Bauform weisen in der Regel starke Magnete, die beispielsweise aus NdFeB (Neodymeisenbor) hergestellt sind, auf, welche jedoch bei Kontakt mit Kraftstoff stark oxidieren und dabei ihre magnetischen Eigenschaften verändern, wodurch die Funktion der elektrischen Zahnradpumpe nicht mehr gegeben ist. The known in the art electric gear pumps with integrated design usually have strong magnets, which are made for example of NdFeB (Neodymeisenbor), which, however, upon contact with fuel strongly oxidize and thereby change their magnetic properties, whereby the function of the electric gear pump is no longer given.
Um dies zu vermeiden, ist es daher erforderlich, diese NdFeB-Magnete vor ei- nem Kontakt mit Kraftstoff zu schützen. Aus dem Stand der Technik sind dazuTo avoid this, it is therefore necessary to protect these NdFeB magnets from contact with fuel. From the prior art are to
Varianten bekannt, die ein Beschichten der Magnete mit Nickel oder Ni-Cu-Ni umfassen. Jedoch ist ein dauerhafter Schutz der Magnete vor einem Kontakt mit Kraftstoff hierdurch auch nicht möglich. Eine andere aus dem Stand der Technik bekannte Variante sieht vor, Magnete nicht aus NdFeB herzustellen sondern aus Eisen-Ferrit, das dem Kontakt mit Kraftstoff standhält. Jedoch sind solche Magnete lediglich schwach magnetisch, so dass sie für den Einsatz in einer elektrischen Zahnradpumpe nicht geeignet sind. Variants are known which comprise coating the magnets with nickel or Ni-Cu-Ni. However, a permanent protection of the magnets from contact with fuel is not possible. Another variant known from the prior art provides magnets not made of NdFeB but of iron ferrite, which withstands contact with fuel. However, such magnets are only weakly magnetic, so they are not suitable for use in an electric gear pump.
Daher ist es wünschenswert, eine Zahnradpumpe und ein Verfahren zum Herstellen einer Zahnradpumpe bereitzustellen, bei welcher starke Magnete effektiv vor einem Kontakt mit Kraftstoff geschützt werden können. Therefore, it is desirable to provide a gear pump and a method of manufacturing a gear pump in which strong magnets can be effectively protected from contact with fuel.
Offenbarung der Erfindung Vorteile der Erfindung Erfindungsgemäß wird eine Zahnradpumpe zum Fördern eines fluidförmigenDISCLOSURE OF THE INVENTION Advantages of the Invention According to the invention, a gear pump is provided for conveying a fluid
Mediums, insbesondere zum Fördern von Kraftstoff in einem Kraftstoffeinspritzsystem, bereitgestellt, welche eine Pumpeneinheit und eine Antriebseinheit aufweist, welche gemeinsam in einem Gehäuse angeordnet sind, wobei die Antriebseinheit einen Motor mit einer Vielzahl von Wicklungen umfasst, welche mit Strom beaufschlagbar sind, um ein umlaufendes Magnetfeld zu erzeugen, und wobei die Pumpeneinheit ein drehbar gelagertes außenverzahntes Zahnrad und einen innenverzahnten Zahnring aufweist, welche exzentrisch zueinander gelagert sind, zusammen eine Verzahnung bilden und zur Erzeugung einer Förderwirkung in kämmendem Eingriff stehen, wobei der als Rotor wirkende innenver- zahnte Zahnring mit einer Vielzahl von Magneten versehen ist, wobei jeder von der Vielzahl von Magneten in dem innenverzahnten Zahnring eingebettet ist und vollständig von dem Material des innenverzahnten Zahnrings umgeben ist. Durch vollständiges Einbetten der Magnete in dem Material des innenverzahnten Zahnrings sind die Magnete vor der Einwirkung von Kraftstoff geschützt, da dieser nicht in das Innere des Zahnrings eindringen kann. Eine Oxidation der Magnete durch Kraftstoff wird dadurch verhindert und die Magnete behalten ihre magnetischen Eigenschaften über einen langen Zeitraum. Medium, in particular for conveying fuel in a fuel injection system, provided, which has a pump unit and a drive unit, which are arranged together in a housing, wherein the drive unit comprises a motor having a plurality of windings, which can be acted upon by current to a circulating Magnetic field to produce, and wherein the pump unit has a rotatably mounted externally toothed gear and an internally toothed ring, which are mounted eccentrically to each other, together form a toothing and are in meshing engagement to produce a conveying action, said acting as a rotor internally toothed toothed ring with a Variety of magnets is provided, wherein each of the plurality of magnets is embedded in the internal toothed ring and completely surrounded by the material of the internal toothed ring. By fully embedding the magnets in the material of the internally toothed ring, the magnets are protected from the action of fuel, as this can not penetrate into the interior of the ring gear. Oxidation of the magnets by fuel is thereby prevented and the magnets retain their magnetic properties over a long period of time.
Gemäß einer bevorzugten Ausführungsform ist der innenverzahnte Zahnring mittels eines MIM-(Metal Injection Molding)-Verfahrens hergestellt. Dies ist eine kos- tengünstige und effektive Variante, um die Einbettung der Magnete in dem Zahnring zu realisieren. According to a preferred embodiment, the internal toothed ring is produced by means of an MIM (Metal Injection Molding) method. This is a cost-effective and effective variant to realize the embedding of the magnets in the toothed ring.
Gemäß noch einer bevorzugten Ausführungsform ist das Material des innenverzahnten Zahnrings Stahl. According to yet a preferred embodiment, the material of the internal toothed ring is steel.
Vorzugsweise sind die Magnete aus NdFeB (Neodymeisenbor) hergestellt. Diese Magnete sind besonders stark und daher gut für die Verwendung in einer elektrischen Zahnradpumpe geeignet. Gemäß noch einer weiteren bevorzugten Ausführungsform ist die Zahnradpumpe als Innenzahnradpumpe ausgebildet. Preferably, the magnets are made of NdFeB (Neodymeisenbor). These magnets are particularly strong and therefore well suited for use in an electric gear pump. According to yet another preferred embodiment, the gear pump is designed as an internal gear pump.
Gemäß der Erfindung wird darüber hinaus ein Verfahren zum Herstellen einer Zahnradpumpe bereitgestellt, welches einen Schritt zum Herstellen eines als Ro- tor wirkenden innenverzahnten Zahnrings mittels eines MIM-(Metal Injection Mol- ding)-Verfahrens umfasst, welches die Schritte aufweist des Positionierens einer Vielzahl von Magneten in einem MIM-Werkzeug mittels einer Vielzahl von Rückzugskernen, welche während des MIM-Verfahrens aus einer durch das MIM- Werkzeug gebildeten Kavität zurückgezogen werden; und Durchführens des MIM-Verfahrens zum Bilden des innenverzahnten Zahnrings. Durch Anwenden eines MIM-Verfahrens zum Bilden des innenverzahnten Zahnrings können die Magnete während dessen Herstellung auf einfache Weise in dem Zahnring eingebettet und somit geschützt werden. Durch Verwenden der sogenannten Rückzugskerne ist es möglich, die Magnete vollständig durch das Material, aus wel- ehern der Zahnring hergestellt wird, zu umschließen. Vorzugsweise wird der mittels des MIM-Verfahrens gebildete innenverzahnte Zahnring, in welchen eine Vielzahl von Magneten vollständig eingebettet sind, mittels eines spanenden Bearbeitungsschrittes nachbearbeitet. Der innenverzahnte Zahnring sollte vorzugsweise nach der Bearbeitung keine offenporige Po- rosität aufweisen, um so einen besonders effektiven Schutz für die darin eingebetteten Magnete vor korrosiven Einwirkungen vorzusehen. According to the invention, there is further provided a method of manufacturing a gear pump comprising a step of manufacturing a rotor-toothed ring gear by a MIM (Metal Injection Molten) method comprising the steps of positioning a plurality magnets in a MIM tool by means of a plurality of retraction cores withdrawn from a cavity formed by the MIM tool during the MIM process; and performing the MIM method of forming the internal toothed ring. By applying an MIM method for forming the internal toothed ring, the magnets can be easily embedded in the ring gear during its manufacture and thus protected. By using the so-called retraction cores, it is possible to completely enclose the magnets by the material from which the toothed ring is made. Preferably, the internally toothed toothed ring formed by means of the MIM method, in which a plurality of magnets are completely embedded, is reworked by means of a machining step. The internally toothed ring should preferably not have any open-pore porosity after machining in order to provide a particularly effective protection for the magnets embedded therein against corrosive actions.
Besonders bevorzugt ist es darüber hinaus, wenn die Vielzahl von in den innenverzahnten Zahnring eingebetteten Magnete nach Beendigung des MIM- Verfahrens, insbesondere nach dem spanenden Bearbeitungsschritt, nachträglich magnetisiert werden. Moreover, it is particularly preferred if the plurality of magnets embedded in the internal toothed ring are subsequently magnetized after the end of the MIM process, in particular after the machining step.
Kurze Beschreibung der Zeichnungen Brief description of the drawings
Im Nachfolgenden werden Ausführungsbeispiele der Erfindung unter Bezugnahme auf die beigefügten Zeichnungen näher beschrieben. Es zeigt: Hereinafter, embodiments of the invention will be described in more detail with reference to the accompanying drawings. It shows:
Fig. 1 eine elektrische Zahnradpumpe in auseinandergezogenen Einzelteilen gemäß einer Ausführungsform; 1 shows an electric gear pump in exploded parts according to an embodiment.
Fig. 2 die Kernkomponenten der in Fig. 1 dargestellten Zahnradpumpe; und Fig. 2 shows the core components of the gear pump shown in Fig. 1; and
Fig. 3 einen halben Schnitt durch einen innenverzahnten Zahnring einer Zahnradpumpe gemäß einer Ausführungsform. Fig. 3 is a half section through an internally toothed ring gear pump according to one embodiment.
Ausführungsformen der Erfindung In Fig. 1 ist eine elektrische Zahnradpumpe 1 in auseinandergezogenen Einzelteilen gemäß dem Stand der Technik dargestellt. Die hier dargestellte elektrische Zahnradpumpe 1 ist von der sogenannten„integrierten Bauform", bei welcher die Antriebseinheit 2, welche hier den Stator 3 mit den Wicklungen 4 (siehe Fig. 2) und mit einem Stecker 16 umfasst, und die Pumpeneinheit 5, welche hier den als Rotor wirkenden innenverzahnten Zahnring 6 und das außenverzahnte ZahnradEMBODIMENTS OF THE INVENTION In Fig. 1, an electric gear pump 1 is shown in exploded parts according to the prior art. The electric gear pump 1 shown here is of the so-called "integrated design", in which the drive unit 2, which here includes the stator 3 with the windings 4 (see FIG. 2) and with a plug 16, and the pump unit 5, which here acting as a rotor internal gear ring 6 and the externally toothed gear
7 (Ritzel) umfasst, als nicht trennbare Einheit ausgebildet sind, so dass sie ge- meinsam in einem Gehäuse 8 angeordnet werden können. Das Gehäuse 8 ist mittels eines Deckels 9, in welchem auch ein saugseitiger Zulaufkanal 10 und ein druckseitiger Ablaufkanal, welche jeweilig als Zu- und Ablaufniere ausgebildet sind, sowie ein Axiallager 12, auf welchem das außenverzahnte Zahnrad 7 gelagert wird, vorgesehen sind, verschlossen. Darüber ist der Deckel 9 mit einer Vielzahl von Rippen 13 ausgebildet. Weiterhin ist in der Figur erkennbar, dass eine Vielzahl von Magneten 14, sechs Stück in der Ausführungsform, an dem als Rotor wirkenden innenverzahnten Zahnring 6 vorgesehen sind, welche hier mittels Kleben in dafür am Rotor vorgesehenen Ausnehmungen in diesem fixiert sind. 7 (pinion) are formed as a non-separable unit, so that they can be arranged together in a housing 8. The housing 8 is by means of a cover 9, in which also a suction-side inlet channel 10 and a pressure-side drain channel, which are respectively designed as inflow and drain kidney, and a thrust bearing 12, on which the externally toothed gear 7 is mounted, are provided closed. In addition, the lid 9 is formed with a plurality of ribs 13. Furthermore, it can be seen in the figure that a multiplicity of magnets 14, six pieces in the embodiment, are provided on the internal toothed ring 6 acting as a rotor, which are fixed therein by means of gluing in recesses provided thereon on the rotor.
Fig. 2 zeigt die Kernkomponenten der in Figur 1 dargestellten Zahnradpumpe 1 ohne das sie umgebende Gehäuse 8. Wie hier erkennbar ist, bilden der innenverzahnte Zahnring 6 und das außenverzahnte Zahnrad 7 zusammen eine Verzahnung 18, in welcher eine Vielzahl von Förderräumen 15 gebildet wird. Das außenverzahnte Zahnrad 3 ist exzentrisch zum innenverzahnten Zahnring 2 drehbar auf dem in Fig. 1 dargestellten Axiallager 12 angeordnet. Wrd das außenverzahnte Zahnrad 3 in eine Drehbewegung versetzt, so kämmt die Außenverzahnung des außenverzahnten Zahnrads 3 in der Innenverzahnung des innenverzahnten Zahnrings 2 und erzeugt einen Fördervolumenstrom des Fluids, in welchem die Verzahnung 18 läuft. Für den Antrieb der elektrischen Zahnradpumpe 1 werden die Wcklungen 4 so mit Strom beaufschlagt, dass ein umlaufendes Magnetfeld erzeugt wird. Wie auch hier gut erkennbar ist, sind die Magnete 14, welche in den Rotor mittels Kleben integriert sind, an einer Oberfläche 17 des innenverzahnten Zahnrings 6 exponiert, so dass Kraftstoff, welcher durch die Zahnradpumpe 1 fließt, die Magnete 14 oxidieren und deren Magnetwirkung verschlechtern kann. FIG. 2 shows the core components of the gear pump 1 shown in FIG. 1 without the surrounding housing 8. As can be seen here, the internally toothed toothed ring 6 and the externally toothed gear 7 together form a toothing 18 in which a multiplicity of delivery chambers 15 are formed. The externally toothed gear 3 is arranged eccentrically to the internal toothed ring 2 rotatably on the axial bearing 12 shown in FIG. Wrd the externally toothed gear 3 is set in a rotational movement, so meshes with the external teeth of the externally toothed gear 3 in the internal toothing of the internally toothed ring 2 and generates a delivery volume flow of the fluid in which the toothing 18 runs. For driving the electric gear pump 1, the coils 4 are supplied with current such that a circulating magnetic field is generated. As can also be clearly seen here, the magnets 14, which are integrated into the rotor by means of adhesion, are exposed on a surface 17 of the internally toothed ring 6, so that fuel flowing through the gear pump 1 oxidises the magnets 14 and deteriorates their magnetic action can.
Fig. 3 zeigt einen halben Schnitt durch einen als Rotor wirkenden innenverzahnten Zahnring 6 einer Zahnradpumpe 1 , welcher mit einem außenverzahnten Zahnrad 7 die Verzahnung 18 bildet, gemäß einer Ausführungsform. Wie hier erkennbar ist, sind die Magnete 14 vollständig in das Material des innenverzahnten Zahnrings 6 eingebettet, welcher aus Stahl mittels eines MIM-(Metal Injection Molding)-Verfahrens hergestellt worden ist. Da der innenverzahnte Zahnring 6 die Magnete 14 vollständig umgibt, ist es für den Kraftstoff, der durch die Zahn- radpumpe 1 hindurch gepumpt wird, nicht möglich, die Magnete 14 zu kontaktieren und durch den Kontakt zu oxidieren. Es können starke Magnete, beispiels- weise aus NdFeb, verwendet werden, die nicht zusätzlich beschichtet werden müssen. Der innenverzahnte Zahnring 6 bietet einen dauerhaften und effektiven Schutz für die vollständig darin eingebetteten Magnete Zum Herstellen eines derartigen innenverzahnten Zahnrings 6 werden die Magnete 14 vor dem MIM- Prozess in eine entsprechende Form eingelegt. Positioniert werden die Magnete 14 dabei durch sogenannte „Rückzugskerne", welche während des MIM- Prozesses wieder aus der durch die Form gebildete Kavität zurückgezogen werden, um ein vollständiges Umschließen der Magnete 14 durch das Material des zu bildenden innenverzahnten Zahnrings 6 bzw. Rotors zu ermöglichen. Da der MIM-Prozess durch bereits magnetisierte Magnete 14 möglicherweise negativ beeinflusst werden könnte und sich aufgrund der hohen Prozesstemperaturen die Magnete 14 ohnehin entmagnetisieren würden, werden die Magnete 14 in einem nachfolgenden Prozess, welcher einer spanenden Nachbearbeitung des zu bildenden innenverzahnten Zahnrings 6 folgt, magnetisiert. Fig. 3 shows a half section through an acting as a rotor internal gear ring 6 of a gear pump 1, which forms the teeth 18 with an externally toothed gear 7, according to one embodiment. As can be seen here, the magnets 14 are completely embedded in the material of the internal toothed ring 6, which has been made of steel by means of a MIM (Metal Injection Molding) method. Since the internal gear ring 6 completely surrounds the magnets 14, it is not possible for the fuel that is pumped through the gear pump 1 to contact the magnets 14 and oxidize by the contact. Strong magnets, for example from NdFeb, which need not be additionally coated. The internally toothed ring gear 6 provides a durable and effective protection for the magnets completely embedded therein. To produce such an internally toothed ring gear 6, the magnets 14 are inserted into a corresponding shape prior to the MIM process. The magnets 14 are thereby positioned by so-called "retraction cores", which are withdrawn again from the cavity formed by the mold during the MIM process in order to allow the magnets 14 to be completely surrounded by the material of the internally toothed ring 6 or rotor to be formed Since the MIM process could possibly be adversely affected by already magnetized magnets 14 and because of the high process temperatures, the magnets 14 would be demagnetized anyway, the magnets 14 are subjected to a subsequent process, which involves a subsequent machining of the internal toothed ring 6 to be formed, magnetized.
Der so hergestellte innenverzahnte Zahnring 6 bietet einen effektiven und dauerhaften Schutz für die Magnete 14, so dass die Zahnradpumpe 1 gemäß der Erfindung über einen langen Zeitraum optimal arbeitet. The internal toothed ring 6 thus produced provides effective and lasting protection for the magnets 14, so that the gear pump 1 according to the invention operates optimally over a long period of time.

Claims

Ansprüche claims
1. Zahnradpumpe (1) zum Fördern eines fluidförmigen Mediums, insbesondere zum Fördern von Kraftstoff in einem Kraftstoffeinspritzsystem, welche eine Pumpeneinheit (5) und eine Antriebseinheit (2) aufweist, welche gemeinsam in einem Gehäuse (8) angeordnet sind, wobei die Antriebseinheit (2) einen Motor mit einer Vielzahl von Wicklungen (4) umfasst, welche mit Strom beaufschlagbar sind, um ein umlaufendes Magnetfeld zu erzeugen, und wobei die Pumpeneinheit (5) ein drehbar gelagertes außenverzahntes Zahnrad (7) und einen innenverzahnten Zahnring (6) aufweist, welche exzentrisch zueinander gelagert sind, zusammen eine Verzahnung (18) bilden und zur Erzeugung einer Förderwirkung in kämmendem Eingriff stehen, wobei der als Rotor wirkende innenverzahnte Zahnring (6) mit einer Vielzahl von Magneten (14) versehen ist, 1. Gear pump (1) for conveying a fluid medium, in particular for conveying fuel in a fuel injection system, which has a pump unit (5) and a drive unit (2), which are arranged together in a housing (8), wherein the drive unit ( 2) comprises a motor having a plurality of windings (4) which can be energized to produce a circulating magnetic field, and wherein the pump unit (5) comprises a rotatably mounted externally toothed gear (7) and an internally toothed ring gear (6) which are mounted eccentrically to each other, together form a toothing (18) and are in meshing engagement for producing a conveying action, wherein the internal toothed ring gear (6) acting as a rotor is provided with a plurality of magnets (14),
dadurch gekennzeichnet, dass  characterized in that
jeder von der Vielzahl von Magneten (14) in dem innenverzahnten Zahnring (6) eingebettet ist und vollständig von dem Material des innenverzahnten Zahnrings (6) umgeben ist.  each of the plurality of magnets (14) is embedded in the internal gear ring (6) and completely surrounded by the material of the internal gear ring (6).
2. Zahnradpumpe (1) gemäß Anspruch 1 , 2. gear pump (1) according to claim 1,
dadurch gekennzeichnet, dass  characterized in that
der innenverzahnte Zahnring (6) mittels eines MIM-(Metal Injection Molding)- Verfahrens hergestellt ist.  the internally toothed ring gear (6) is made by means of a MIM (Metal Injection Molding) method.
3. Zahnradpumpe (1) gemäß Anspruch 1 oder 2, 3. gear pump (1) according to claim 1 or 2,
dadurch gekennzeichnet, dass  characterized in that
das Material des innenverzahnten Zahnrings (6) Stahl ist.  the material of the internal toothed ring (6) is steel.
4. Zahnradpumpe (1) nach einem oder mehreren der Ansprüche 1 bis 3, 4. gear pump (1) according to one or more of claims 1 to 3,
dadurch gekennzeichnet, dass  characterized in that
die Magnete (14) aus NdFeB hergestellt sind. Zahnradpumpe (1) nach einem oder mehreren der Ansprüche 1 bis 4, dadurch gekennzeichnet, dass the magnets (14) are made of NdFeB. Gear pump (1) according to one or more of claims 1 to 4, characterized in that
die Zahnradpumpe (1) als Innenzahnradpumpe ausgebildet ist. the gear pump (1) is designed as an internal gear pump.
Verfahren zum Herstellen einer Zahnradpumpe (1), insbesondere gemäß einem oder mehreren der Ansprüche 1 bis 5, Method for producing a gear pump (1), in particular according to one or more of claims 1 to 5,
dadurch gekennzeichnet, dass characterized in that
zum Herstellen eines als Rotor wirkenden innenverzahnten Zahnrings (6) ein MIM-(Metal Injection Molding)-Verfahren angewendet wird, welches die folgenden Schritte aufweist for producing an internally toothed ring gear (6) acting as a rotor, an MIM (Metal Injection Molding) method is applied which comprises the following steps
Positionieren einer Vielzahl von Magneten (14) in einem MIM-Werkzeug mittels einer Vielzahl von Rückzugskernen, welche während des MIM- Verfahrens aus einer durch das MIM-Werkzeug gebildeten Kavität zurückgezogen werden;  Positioning a plurality of magnets (14) in a MIM tool by means of a plurality of retraction cores withdrawn from a cavity formed by the MIM tool during the MIM process;
Durchführen des MIM-Verfahrens zum Bilden des innenverzahnten Zahnrings (6).  Performing the MIM process for forming the internally toothed ring (6).
Verfahren gemäß Anspruch 6, Method according to claim 6,
dadurch gekennzeichnet, dass characterized in that
der mittels des MIM-Verfahrens gebildete innenverzahnte Zahnring (6), in welchen eine Vielzahl von Magneten (14) vollständig eingebettet sind, mittels eines spanenden Bearbeitungsschrittes nachbearbeitet wird. the internally toothed toothed ring (6) formed by means of the MIM method, in which a plurality of magnets (14) are completely embedded, is reworked by means of a machining step.
Verfahren gemäß Anspruch 8 oder 9, Method according to claim 8 or 9,
dadurch gekennzeichnet, dass characterized in that
die Vielzahl von in den innenverzahnten Zahnring (6) eingebetteten Magnete (14) nach Beendigung des MIM-Verfahrens, insbesondere nach dem spanenden Bearbeitungsschritt, nachträglich magnetisiert werden. the plurality of embedded in the internally toothed ring gear (6) magnets (14) after completion of the MIM process, in particular after the machining step, are subsequently magnetized.
EP12735309.2A 2011-09-13 2012-07-18 Gear pump and method for producing a gear pump Withdrawn EP2756194A1 (en)

Applications Claiming Priority (2)

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DE201110082577 DE102011082577A1 (en) 2011-09-13 2011-09-13 Gear pump and method of manufacturing a gear pump
PCT/EP2012/064051 WO2013037535A1 (en) 2011-09-13 2012-07-18 Gear pump and method for producing a gear pump

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DE102015212061A1 (en) * 2015-06-29 2016-12-29 Zf Friedrichshafen Ag Electrically driven pump

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IT1245466B (en) * 1991-03-19 1994-09-20 Iveco Fiat ELECTRIC PUMP FOR THE CIRCULATION OF A LIQUID, FOR EXAMPLE IN AN INTERNAL COMBUSTION ENGINE
DE4447284A1 (en) * 1994-12-30 1996-07-04 Eberspaecher J Fuel metering pump of a vehicle heater or a particle filter regeneration burner
WO1996041080A1 (en) * 1995-06-07 1996-12-19 Concis, L.L.C. Microfabricated, tube located gear pump system
DE29913367U1 (en) * 1999-07-30 1999-12-09 Pumpenfabrik Ernst Scherzinger Internal gear pump, the ring gear of which is the inside of a rotor of an electric motor
GB0130602D0 (en) * 2001-12-21 2002-02-06 Johnson Electric Sa Brushless D.C. motor
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