EP0147567B1 - Gear pump, particularly for medical purposes - Google Patents

Gear pump, particularly for medical purposes Download PDF

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Publication number
EP0147567B1
EP0147567B1 EP84113140A EP84113140A EP0147567B1 EP 0147567 B1 EP0147567 B1 EP 0147567B1 EP 84113140 A EP84113140 A EP 84113140A EP 84113140 A EP84113140 A EP 84113140A EP 0147567 B1 EP0147567 B1 EP 0147567B1
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EP
European Patent Office
Prior art keywords
pump
shaft
gear pump
hub
plastic
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
Application number
EP84113140A
Other languages
German (de)
French (fr)
Other versions
EP0147567A3 (en
EP0147567A2 (en
Inventor
Wolfgang Zenglein
Franz-Josef Weinbeer
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.)
Fresenius SE and Co KGaA
Original Assignee
Fresenius SE and Co KGaA
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Publication date
Application filed by Fresenius SE and Co KGaA filed Critical Fresenius SE and Co KGaA
Publication of EP0147567A2 publication Critical patent/EP0147567A2/en
Publication of EP0147567A3 publication Critical patent/EP0147567A3/en
Application granted granted Critical
Publication of EP0147567B1 publication Critical patent/EP0147567B1/en
Expired legal-status Critical Current

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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
    • 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
    • F04C2/082—Details specially related to intermeshing engagement type machines or pumps
    • F04C2/084—Toothed wheels
    • 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
    • F04C15/0061—Means for transmitting movement from the prime mover to driven parts of the pump, e.g. clutches, couplings, transmissions
    • F04C15/0073—Couplings between rotors and input or output shafts acting by interengaging or mating parts, i.e. positive coupling of rotor and shaft
    • 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
    • F04C15/0061—Means for transmitting movement from the prime mover to driven parts of the pump, e.g. clutches, couplings, transmissions
    • F04C15/0069—Magnetic couplings
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05C—INDEXING SCHEME RELATING TO MATERIALS, MATERIAL PROPERTIES OR MATERIAL CHARACTERISTICS FOR MACHINES, ENGINES OR PUMPS OTHER THAN NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES
    • F05C2225/00—Synthetic polymers, e.g. plastics; Rubber
    • F05C2225/04—PTFE [PolyTetraFluorEthylene]

Definitions

  • the invention relates to a gear pump according to the preamble of claim 1.
  • Gear pumps are used in medicine, for example in the field of dialysis.
  • a generic gear pump which is also used in this area of medicine, among other things, has a pump housing which has a base plate, a cover plate and a housing middle part arranged between them.
  • At least two pump wheels are arranged in the pump chamber of the middle part of the housing, which consist of a special steel in the gear pump of the generic type.
  • the pump wheels are mounted on rotating shafts, a magnet being attached to the shaft of the driving pump wheel, which is in engagement with the driven pump wheel, which forms part of a magnetic coupling for transmitting the driving forces to the shaft of the driving pump wheel.
  • Both the shafts of the pump wheels and their bearing bushes for storage in the pump housing are made of a high-strength metal, such as Widia steel, in the generic gear pump, so that a clean guidance of the pump wheels, some of which run at high speed, and their shafts is ensured.
  • the generic gear pump has the serious disadvantage that despite the use of expensive materials that are considered wear-resistant, despite a considerable number of gear pumps, which are used in particular in the medical field, after a relatively short period of use, there are considerable signs of wear, particularly in the area of the shafts Pump wheels and their bearings occur in the pump housing. As tests carried out within the scope of the invention have shown, these wear phenomena are due to material decomposition of the bearings and the shafts due to the use of aggressive cleaning media such as, for example, acetic acid.
  • a gear pump according to the preamble of claim 1 emerges from GB-PS-1 002 766.
  • the provision of fixed axles for the pump wheels initially ensures that no bearings are required for rotating shafts in the gear pump according to the invention, which bearings are very sensitive to wear, particularly when using aggressive cleaning agents.
  • the gear pump according to the invention thus has the advantage that it has high stability even when used in areas in which cleaning of the gear pump by means of aggressive media is unavoidable, since bearing wear cannot occur.
  • gear pump according to the invention Another advantage of the gear pump according to the invention is that no or no significant wear occurs in the area between the pump wheels and fixed axles due to the use of suitable plastics, so that there is no shift in the wear problem from the mounting of the rotating shafts to the mounting the pump wheels rotating on the fixed axles. Further investigations carried out within the scope of the invention have shown that the use of pump wheels made of plastic is also entirely possible for the above-mentioned critical fields of application, in particular in the field of medicine.
  • the provision of the hollow shaft which is connected on the one hand to the driving pump wheel and on the other hand to one of the magnets of the magnetic coupling, ensures that a drive connection between the magnet and the driving pump wheel is possible, although the driving pump wheel is arranged freely rotating on a fixed axis is. Furthermore, there is the advantage that none in the region of the hollow shaft measurable wear occurs because it also consists of a very resistant plastic with very good running properties.
  • the shaft that connects the driving pump wheel to the magnet is designed as a hollow shaft in the gear pump according to the invention, which rotates on the fixed axis, there are no problems with flexibility in the gear pump according to the invention, since the hollow shaft extends over its entire length on the fixed axis Axle can support and also has a much larger effective diameter than in the previously described basically conceivable possibility of a rotating shaft with a diameter that would correspond approximately to the diameter of the axes of the gear pump according to the invention. A correspondingly larger dimensioning of such conceivable plastic shafts is unsuitable for reasons of the increased space requirement and the growing overall size of the gear pump.
  • pump wheels and the hollow shaft are formed from polytetrafluoroethylene graphite according to the advantageous further development according to claim 2, particularly favorable running properties result on the fixed axle journal and furthermore this material has proven to be particularly resistant to all media used in the field of dialysis.
  • the driving pump unit and the hollow shaft can be formed in one piece, which has advantages in terms of production.
  • these two components of the gear pump according to the invention can also be connected to one another in other ways, should this be necessary for any design reasons.
  • the pump wheel and the hollow shaft could be connected to one another by means of a pin connection.
  • journal of the driven pump wheel is guided only in the cover plate of the pump housing, there is the advantage that a further guide recess in the base plate of the pump housing can be omitted, which reduces the manufacturing outlay.
  • Such one-sided guidance of the axle journal is possible in the gear pump according to the invention because the axle journal is not excessively long and, in addition, on the side of the driven pump wheel, no forces are transmitted to the axle journal that great guidance would be required on both sides.
  • the magnet of the magnetic coupling is arranged on a hub which can be fastened to the hollow shaft, there is the advantage that the fastening of the magnet can be provided on a part which is independent of the hollow shaft, so that the formation of the hollow shaft itself above all from the point of view optimal running properties on the fixed axle journal and wear resistance takes into account, whereas the problem of fastening the magnet is limited to the hub, which then only has to be fastened to the hollow shaft.
  • the gear pump 1 shows a gear pump 1 according to the invention, which is particularly suitable for medical purposes such as dialysis.
  • the gear pump 1 has a pump housing 2 which has a base plate 3, a cover plate 4 and a housing middle part 5.
  • the middle housing part 5 is arranged between the base plate 3 and the cover plate 4 and connected to them, for example, by means of screws or similar fastening means.
  • This cover plate 4 is arranged on the bearing side, that is to say opposite to the magnetic coupling.
  • the middle housing section 5 has a pump chamber 6, in which two pump wheels 7 and 8 are arranged in the example.
  • the pump wheel 7 is the driving pump wheel, while the pump wheel 8 is driven.
  • the pump wheel 8 is engaged with the pump wheel 7.
  • a hood 9 is further fastened in a manner not shown.
  • a magnet 11 is arranged, which forms part of a magnetic coupling, not shown, for transmitting the driving forces for the gear pump 1.
  • the pump wheels 7 and 8 are each arranged on a fixed axle journal 12 or 13.
  • the axle journals 12 and 13 are fastened in corresponding guide recesses 14 and 15 of the cover plate 4, for which purpose an adhesive was used in the example.
  • V4A steel for example, has proven to be a suitable material for the axle journals 12 and 13, while an adhesive with the name Loctite 648®, for example, is suitable as a connecting means with the cover plate 4.
  • the axle journals 12 and 13 can be arranged in the pump housing 2 in an exactly guided manner, without further guide recesses or the like being necessary. This has the advantage that additional guide recesses in the base plate 3 can be dispensed with, which considerably reduces their production outlay.
  • Polytetrafluoroethylene graphite (Teflon graphite) has proven to be a particularly suitable material for the pump wheels 7 and 8, since this material has particularly good running properties, so that wear occurs between the pump wheels 7 and 8 and the associated axle journals 12 and 13, respectively does not occur or occurs to a negligible extent. Furthermore, the material mentioned for the pump wheels 7 and 8 is resistant to all the usual media which have to be conveyed, in particular in the medical field, for example in the dialysis of gear pumps, or are used for cleaning them.
  • the pump wheels 7 and 8 can be provided with helical teeth, for which purpose the driving pump wheel 7 can be helically toothed, for example, 6 ° to the left, while the driven pump wheel 8 corresponds to FIG. 6 ° can be helically toothed on the right.
  • the driving pump wheel 7 is connected to a shaft 16, which according to the invention is designed as a hollow shaft.
  • the shaft 16 is integrally connected to the pump wheel 7 and consists of the same material.
  • the one-piece design of the pump wheel 7 and the shaft 16 results in a compact and stable structural unit which is also suitable for the transmission of high torques.
  • the one-piece construction of pump wheel 7 and shaft 16 illustrated in the example case can, however, also be replaced by another connection between the named components if necessary, for which purpose a pin connection is suitable, for example.
  • the pump wheel 7 and the shaft 16 designed as a hollow shaft each have a passage recess 17 or 18, which in the case of the one-piece construction form a single continuous passage recess.
  • the shaft 16 On the side facing away from the impeller 7, the shaft 16 has a locking recess 19 which has an area 20 which extends in the axial direction of the shaft and an area 21 which extends in the radial direction of the shaft 16.
  • a further locking recess 22 is arranged on the side of the shaft 16 diametrically opposite the locking recess 19, which is designed in accordance with the configuration of the locking recess 19, but the radial regions 21 and 23 of the locking recesses 19 and 22 as shown in FIG. 3, extend once upwards or downwards once, that is to say are arranged symmetrically to the center of the shaft 16.
  • the magnet 11 is arranged on a hub 24, which in the example has a cylindrical sleeve 25 with an inner recess 26 and an annular flange 27 arranged at one end of the sleeve 25.
  • the annular flange 27 has an inner recess 28 with a diameter which corresponds to that of the inner recess of the sleeve 25.
  • the sleeve 25 is further provided with two radially opposite recesses 29 and 30, in which locking pins 31 and 32 are fastened, for example by means of an adhesive.
  • the magnet 11 itself is arranged on the outer circumference of the sleeve 25 and can also be attached to the sleeve 25 by means of an adhesive.
  • the pump wheel 7 and the shaft 16 connected to it are arranged on the journal 12, the shaft 16 being supported over its entire length on the journal 12, so that despite the plastic material for the Wave 16 no deflections are to be feared.
  • these have passage recesses 34 and 35, respectively.
  • the hub is 24 arranged with the magnet 11 attached to it in the example on the area of the shaft 16 projecting into the space 10 of the hood 9, the locking pins 31 and 32 engaging in the corresponding locking recesses 19 and 22, respectively.
  • the locking recesses 19 and 23 and the locking pins 31 and 32 form a bayonet lock, which builds up its locking action after rotation of the hub 24, the locking pins 31 and 32 initially in the axial regions 20 and 36 of the locking recesses 19 and 22 will be introduced.
  • the locking pins 31 and 32 are inserted into the radial areas 21 and 23 of the locking recesses 19 and 22, after which the locking pins 31 and 32 engage behind the corresponding adjacent wall areas of the shaft 16, so that the hub 24 slides off the hollow shaft 16 is prevented.
  • the gear pump 1 according to the invention can be assembled in an extremely inexpensive and quick manner and that, owing to the provision of two fixed axle journals 12 and 13, a number of complex manufacturing and assembly steps are omitted, as is the case with gear pumps with rotating shafts the pump wheels 7 and 8 would be required.
  • the drive connection between the magnet 11 and the driving pump wheel 7 is nevertheless ensured in an extremely simple manner by means of the shaft 16 designed as a hollow shaft, with a sufficiently high stability being achieved despite its plastic construction, since the shaft 16 is over their entire length is supported on the journal 12.
  • this does not increase the wear, since the shaft 16, like the pump wheels 7 and 8, can be made of a wear-resistant plastic with very good running properties, which is also resistant to all media customary in particular in the medical field.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Rotary Pumps (AREA)
  • Details And Applications Of Rotary Liquid Pumps (AREA)
  • Structures Of Non-Positive Displacement Pumps (AREA)

Description

Die Erfindung betrifft eine Zahnradpumpe nach dem Oberbegriff des Anspruchs 1.The invention relates to a gear pump according to the preamble of claim 1.

Zahnradpumpen werden in der Medizin, beispielsweise im Bereich der Dialyse verwendet. Eine gattungsgemäße Zahnradpumpe, die unter anderem auch in diesem Bereich der Medizin Anwendung findet, weist ein Pumpengehäuse auf, das eine Grundplatte, eine Deckplatte und ein zwischen diesen angeordnetes Gehäusemittelteil aufweist. In der Pumpkammer des Gehäusemittelteiles sind wenigstens zwei Pumpenräder angeordnet, die bei der gattungsgemäßen Zahnradpumpe aus einem Sonderstahl bestehen. Die Pumpenräder sind auf drehenden Wellen befestigt, wobei auf der Welle des treibenden Pumpenrades, das mit dem angetriebenen Pumpenrad in Eingriff steht, ein Magnet befestigt ist, der einen Teil einer Magnetkupplung zur Übertragung der Antriebskräfte auf die Welle des treibenden Pumpenrades bildet. Sowohl die Wellen der Pumpenräder als auch deren Lagerbuchsen zur Lagerung im Pumpengehäuse bestehen bei der gattungsgemäßen Zahnradpumpe aus einem hochfesten Metall, wie beispielsweise Widia-Stahl, damit eine saubere Führung der teilweise mit hoher Drehzahl laufenden Pumpenräder und deren Wellen sichergestellt ist.Gear pumps are used in medicine, for example in the field of dialysis. A generic gear pump, which is also used in this area of medicine, among other things, has a pump housing which has a base plate, a cover plate and a housing middle part arranged between them. At least two pump wheels are arranged in the pump chamber of the middle part of the housing, which consist of a special steel in the gear pump of the generic type. The pump wheels are mounted on rotating shafts, a magnet being attached to the shaft of the driving pump wheel, which is in engagement with the driven pump wheel, which forms part of a magnetic coupling for transmitting the driving forces to the shaft of the driving pump wheel. Both the shafts of the pump wheels and their bearing bushes for storage in the pump housing are made of a high-strength metal, such as Widia steel, in the generic gear pump, so that a clean guidance of the pump wheels, some of which run at high speed, and their shafts is ensured.

Hierbei ist jedoch nachteilig, daß die gattungsgemäße Zahnradpumpe aufgrund der verwendeten teueren Materialien und der aufwendigen Herstellung insbesondere im Bereich der Lagerung der drehenden Wellen der Pumpenräder nur sehr kostenintensiv zu fertigen ist.However, it is disadvantageous here that the generic gear pump can only be manufactured very cost-intensively due to the expensive materials used and the complex production, particularly in the area of the bearing of the rotating shafts of the pump wheels.

Weiterhin weist die gattungsgemäße Zahnradpumpe den gravierenden Nachteil auf, daß trotz der Verwendung teuerer Materialien, die als verschleißfest gelten, trotzdem bei einer erheblichen Zahl von Zahnradpumpen, die insbesondere im medizinischen Bereich Anwendung finden, nach relativ kurzer Benutzungsdauer beträchtliche Verschleißerscheinungen insbesondere im Bereich der Wellen der Pumpenräder und deren Lagerungen im Pumpengehäuse auftreten. Wie im Rahmen der Erfindung durchgeführte Untersuchungen ergeben haben, sind diese Verschleißerscheinungen auf Materialzersetzungen der Lager und der Wellen aufgrund der Verwendung von aggressiven Reinigungsmedien wie beispielsweise Essigsäure zurückzuführen. Da jedoch eine Reinigung der Zahnradpumpen insbesondere im Bereich der Dialyse mit derartig aggressiven Reinigungsmitteln aus Hygienegründen unumgänglich ist, eignet sich die gattungsgemäße Zahnradpumpe nur sehr bedingt für die Anwendung im Bereich der Medizin, da sie sich trotz der Verwendung teuerer Materialien häufig als verschleiß- und störanfällig erwiesen hat.Furthermore, the generic gear pump has the serious disadvantage that despite the use of expensive materials that are considered wear-resistant, despite a considerable number of gear pumps, which are used in particular in the medical field, after a relatively short period of use, there are considerable signs of wear, particularly in the area of the shafts Pump wheels and their bearings occur in the pump housing. As tests carried out within the scope of the invention have shown, these wear phenomena are due to material decomposition of the bearings and the shafts due to the use of aggressive cleaning media such as, for example, acetic acid. However, since cleaning the gear pumps, particularly in the area of dialysis, with such aggressive cleaning agents is inevitable for hygiene reasons, the generic gear pump is only suitable to a limited extent for use in the medical field, since, despite the use of expensive materials, it is often prone to wear and failure has proven.

Eine Zahnradpumpe nach dem Oberbegriff des Patentanspruches 1 geht aus der GB-PS-1 002 766 hervor. Eine ähnliche Zahnradpumpe, bei der mittels in Lagerbuchsen geführte und frei drehende, auf massiven metallischen Achszapfen gelagerte Kunststoffzahnräder vorhanden sind, ist auch in der FR-PS-1 139 203 beschrieben.A gear pump according to the preamble of claim 1 emerges from GB-PS-1 002 766. A similar gear pump, in which there are plastic gears guided in bearing bushings and freely rotating and mounted on solid metallic axle journals, is also described in FR-PS-1 139 203.

Es ist daher Aufgabe der Erfindung, eine Zahnradpumpe, insbesondere für medizinische Zwecke, der im Oberbegriff des Anspruchs 1 umrissenen Gattung zu schaffen, die einerseits eine kostengünstige Herstellung und andererseits hohe Verschleißfestigkeit auch für Anwendungsfälle, bei denen aggressive Reinigungsmedien verwendet werden, ermöglicht.It is therefore an object of the invention to provide a gear pump, in particular for medical purposes, of the type outlined in the preamble of claim 1, which, on the one hand, enables inexpensive manufacture and, on the other hand, high wear resistance for applications in which aggressive cleaning media are used.

Diese Aufgabe wird durch die kennzeichnenden Merkmale des Anspruchs 1 gelöst.This object is achieved by the characterizing features of claim 1.

Durch das Vorsehen von feststehenden Achsen für die Pumpenräder wird zunächst erreicht, daß bei der erfindungsgemäßen Zahnradpumpe keine Lager für drehende Wellen erforderlich sind, die insbesondere bei der Verwendung aggressiver Reinigungsmittel sehr verschleißempfindlich sind. Somit weist die erfindungsgemäße Zahnradpumpe den Vorteil auf, daß sie auch bei der Verwendung in Bereichen, in denen die Reinigung der Zahnradpumpe mittels aggressiver Medien unumgänglich ist, hohe Standfestigkeit hat, da ein Lagerverschleiß nicht auftreten kann.The provision of fixed axles for the pump wheels initially ensures that no bearings are required for rotating shafts in the gear pump according to the invention, which bearings are very sensitive to wear, particularly when using aggressive cleaning agents. The gear pump according to the invention thus has the advantage that it has high stability even when used in areas in which cleaning of the gear pump by means of aggressive media is unavoidable, since bearing wear cannot occur.

Ein weiterer Vorteil der erfindungsgemäßen Zahnradpumpe besteht darin, daß auch im Bereich zwischen Pumpenrädern und feststehenden Achsen durch die Verwendung von geeigneten Kunststoffen kein bzw. kein nennenswerter Verschleiß auftritt, so daß es nicht zu einer Verlagerung des Verschleißproblemes von der Lagerung der drehenden Wellen zu der Lagerung der auf den feststehenden Achsen drehenden Pumpenrädern kommt. Daß die Verwendung von aus Kunststoff bestehenden Pumpenrädern auch fur die genannten kritischen Anwendungsgebiete, insbesondere im Bereich der Medizin, durchaus möglich ist, haben weitere im Rahmen der Erfindung durchgeführte Untersuchungen erwiesen.Another advantage of the gear pump according to the invention is that no or no significant wear occurs in the area between the pump wheels and fixed axles due to the use of suitable plastics, so that there is no shift in the wear problem from the mounting of the rotating shafts to the mounting the pump wheels rotating on the fixed axles. Further investigations carried out within the scope of the invention have shown that the use of pump wheels made of plastic is also entirely possible for the above-mentioned critical fields of application, in particular in the field of medicine.

Durch die Paarung der Pumpenräder aus Kunststoff mit den feststehenden Achsen ergibt sich weiterhin der Vorteil, daß bei der erfindungsgemäßen Zahnradpumpe keinerlei Schmierung erforderlich ist, da die Kunststoffpumpenräder sehr gute Laufeigenschaften aufweisen, die eine Schmierung entbehrlich machen.By pairing the plastic pump wheels with the fixed axles there is the further advantage that no lubrication is required in the gear pump according to the invention, since the plastic pump wheels have very good running properties that make lubrication unnecessary.

Durch das Vorsehen der Hohlwelle, die einerseits mit dem treibenden Pumpenrad verbunden ist und andererseits mit einem der Magneten der Magnetkupplung, wird erreicht, daß eine Antriebsverbindung zwischen dem Magneten und dem treibenden Pumpenrad möglich ist, obwohl das treibende Pumpenrad frei drehend auf einer feststehenden Achse angeordnet ist. Weiterhin ergibt sich der Vorteil, daß auch im Bereich der Hohlwelle keine meßbare Abnutzung auftritt, da diese auch aus einem sehr widerstandsfähigen Kunststoff mit sehr guten Laufeigenschaften besteht.The provision of the hollow shaft, which is connected on the one hand to the driving pump wheel and on the other hand to one of the magnets of the magnetic coupling, ensures that a drive connection between the magnet and the driving pump wheel is possible, although the driving pump wheel is arranged freely rotating on a fixed axis is. Furthermore, there is the advantage that none in the region of the hollow shaft measurable wear occurs because it also consists of a very resistant plastic with very good running properties.

Zwar wäre es grundsätzlich denkbar, das Pumpenrad auf einer aus einem entsprechenden Kunststoff bestehenden drehenden Welle zu befestigen, deren gute Laufeigenschaften ebenfalls zumindest einen verminderten Verschleiß im Bereich der Wellenlager erwarten ließe. Jedoch hat sich gezeigt, daß eine derartige Ausführung zu einer zu schwachen und flexiblen Pumpenradwelle führen würde, so daß diese Ausführung ungeeignet erscheint. Da die Welle, die das treibende Pumpenrad mit dem Magneten verbindet bei der erfindungsgemäßen Zahnradpumpe als Hohlwelle ausgebildet ist, die auf der feststehenden Achse umläuft, ergeben sich bei der erfindungsgemäßen Zahnradpumpe hinsichtlich Flexibilität keinerlei Probleme, da sich die Hohlwelle über ihre gesamte Länge auf der feststehenden Achse abstützen kann und überdies einen wesentlich größeren wirksamen Durchmesser aufweist, als bei der zuvor beschriebenen grundsätzlich denkbaren Möglichkeit einer drehenden Welle mit einem Durchmesser, der ungefähr dem Durchmesser der Achsen der erfindungsgemäßen Zahnradpumpe entsprechen würde. Eine entsprechende größere Dimensionierung derartiger denkbarer Kunststoffwellen ist aus Gründen des erhöhten Platzbedarfes und der damit wachsenden Gesamtgröße der Zahnradpumpe ungeeignet.In principle, it would be conceivable to attach the pump wheel to a rotating shaft made of a corresponding plastic, the good running properties of which would also lead to at least reduced wear in the area of the shaft bearings. However, it has been shown that such a design would lead to a weak and flexible impeller shaft, so that this design seems unsuitable. Since the shaft that connects the driving pump wheel to the magnet is designed as a hollow shaft in the gear pump according to the invention, which rotates on the fixed axis, there are no problems with flexibility in the gear pump according to the invention, since the hollow shaft extends over its entire length on the fixed axis Axle can support and also has a much larger effective diameter than in the previously described basically conceivable possibility of a rotating shaft with a diameter that would correspond approximately to the diameter of the axes of the gear pump according to the invention. A correspondingly larger dimensioning of such conceivable plastic shafts is unsuitable for reasons of the increased space requirement and the growing overall size of the gear pump.

Die Unteransprüche haben vorteilhafte Weiterbildungen der Erfindung zum Inhalt.The dependent claims contain advantageous developments of the invention.

Sind die Pumpenräder und die Hohlwelle gemäß der vorteilhaften Weiterbildung nach Anspruch 2 aus Polytetrafluoräthylen-Graphit ausgebildet, ergeben sich besonders günstige Laufeigenschaften auf den feststehenden Achszapfen und weiterhin hat sich dieser Werkstoff als resistent insbesondere gegenüber allen im Bereich der Dialyse verwendeten Medien erwiesen.If the pump wheels and the hollow shaft are formed from polytetrafluoroethylene graphite according to the advantageous further development according to claim 2, particularly favorable running properties result on the fixed axle journal and furthermore this material has proven to be particularly resistant to all media used in the field of dialysis.

Gemäß Anspruch 3 können das treibende Pumpenaggregat und die Hohlwelle einstückig ausgebildet sein, was hinsichtlich der Fertigung Vorteile mit sich bringt. Selbstverständlich können diese beiden Bauteile der erfindungsgemäßen Zahnradpumpe auch auf andere Weise miteinander verbunden werden, falls dies aus irgendwelchen konstruktiven Gründen erforderlich sein sollte. So könnten das Pumpenrad und die Hohlwelle beispielsweise mittels einer Stiftverbindung miteinander verbunden werden.According to claim 3, the driving pump unit and the hollow shaft can be formed in one piece, which has advantages in terms of production. Of course, these two components of the gear pump according to the invention can also be connected to one another in other ways, should this be necessary for any design reasons. For example, the pump wheel and the hollow shaft could be connected to one another by means of a pin connection.

Ist der Achszapfen des angetriebenen Pumpenrades nur in der Deckplatte des Pumpengehäuses geführt, ergibt sich der Vorteil, daß eine weitere Führungsausnehmung in der Grundplatte des Pumpengehäuses entfallen kann, was den Fertigungsaufwand vermindert. Eine derartige einseitige Führung des Achszapfens ist bei der erfindungsgemäßen Zahnradpumpe deshalb möglich, da der Achszapfen nicht übermäßig lang ist und außerdem auf der Seite des angetriebenen Pumpenrades keine so großen Kräfte auf den Achszapfen übertragen werden, daß eine beiderseitige Führung erforderlich wäre.If the journal of the driven pump wheel is guided only in the cover plate of the pump housing, there is the advantage that a further guide recess in the base plate of the pump housing can be omitted, which reduces the manufacturing outlay. Such one-sided guidance of the axle journal is possible in the gear pump according to the invention because the axle journal is not excessively long and, in addition, on the side of the driven pump wheel, no forces are transmitted to the axle journal that great guidance would be required on both sides.

Die Möglichkeit, die feststehenden Achszapfen sowohl des angetriebenen wie des treibenden Pumpenrades in die Deckplatte des Pumpengehäuses einzukleben ergibt insbesondere in fertigungstechnischer Hinsicht Vorteile, da das Kleben sowohl von der Materialals auch der Montageseite her wenig aufwendig ist.The possibility of gluing the fixed axle journals of both the driven and the driving pump wheel into the cover plate of the pump housing results in advantages, particularly in terms of production technology, since the gluing is not very expensive from both the material and the mounting side.

Ist der Magnet der Magnetkupplung auf einer Nabe angeordnet, die an der Hohlwelle befestigt werden kann, ergibt sich der Vorteil, daß die Befestigung des Magneten an einem von der Hohlwelle unabhängigen Teil vorgesehen werden kann, so daß die Ausbildung der Hohlwelle selbst vor allem den Gesichtspunkten optimaler Laufeigenschaften auf dem feststehenden Achszapfen und Verschleißfestigkeit Rechnung trägt, wohingegen das Problem der Befestigung des Magneten auf die Nabe beschränkt ist, die dann lediglich noch an der Hohlwelle befestigt werden muß.If the magnet of the magnetic coupling is arranged on a hub which can be fastened to the hollow shaft, there is the advantage that the fastening of the magnet can be provided on a part which is independent of the hollow shaft, so that the formation of the hollow shaft itself above all from the point of view optimal running properties on the fixed axle journal and wear resistance takes into account, whereas the problem of fastening the magnet is limited to the hub, which then only has to be fastened to the hollow shaft.

Besonders vorteilhaft ist dies durch Aufkleben des Magneten auf der Nabe gelöst, deren Montierbarkeit auf der Hohlwelle weiterhin dadurch optimiert werden kann, wenn die Nabe und die Hohlwelle mittels eines Bajonettverschlusses miteinander verbunden werden können.This is particularly advantageously solved by sticking the magnet on the hub, the mountability of which on the hollow shaft can be further optimized if the hub and the hollow shaft can be connected to one another by means of a bayonet catch.

Weitere Einzelheiten, Merkmale und Vorteile der Erfindung ergeben sich aus nachfolgender Beschreibung eines Ausführungsbeispieles anhand der Zeichnung.Further details, features and advantages of the invention result from the following description of an embodiment with reference to the drawing.

Es zeigtIt shows

  • Fig. 1 eine leicht vereinfachte Darstellung eines Längsschnittes durch eine erfindungsgemäße Zahnradpumpe,1 is a slightly simplified illustration of a longitudinal section through a gear pump according to the invention,
  • Fig. 2 eine teilweise geschnittene vergrößerte Darstellung eines Pumpenrades und einer damit verbundenen Hohlwelle der Zahnradpumpe gemäß Fig. 1,2 is a partially sectioned enlarged view of a pump wheel and an associated hollow shaft of the gear pump of FIG. 1,
  • Fig. 3 eine Ansicht auf das Zahnrad und die Hohlwelle gemäß Fig. 2 aus Richtung des Pfeiles 111 in Fig. 2 undFig. 3 is a view of the gear and the hollow shaft of FIG. 2 from the direction of arrow 111 in Fig. 2 and
  • Fig. 4 eine Fig. 2 entsprechende Darstellung eines Längsschnittes durch eine Nabe und eines darauf befestigten Magneten der Zahnradpumpe gemäß Fig. 1.4 shows a representation corresponding to FIG. 2 of a longitudinal section through a hub and a magnet of the gear pump according to FIG. 1 fastened thereon.

Gemäß Fig. 1 ist eine erfindungsgemäße Zahnradpumpe 1 dargestellt, die insbesondere für medizinische Zwecke wie beispielsweise der Dialyse geeignet ist. Die Zahnradpumpe 1 weist ein Pumpengehäuse 2 auf, das eine Grundplatte 3, eine Deckplatte 4 und ein Gehäusemittelteil 5 aufweist. Das Gehäusemittelteil 5 ist zwischen der Grundplatte 3 und der Deckplatte 4 angeordnet und mit diesen beispielsweise mittels Schrauben oder ähnlichen Befestigungsmitteln verbunden.1 shows a gear pump 1 according to the invention, which is particularly suitable for medical purposes such as dialysis. The gear pump 1 has a pump housing 2 which has a base plate 3, a cover plate 4 and a housing middle part 5. The middle housing part 5 is arranged between the base plate 3 and the cover plate 4 and connected to them, for example, by means of screws or similar fastening means.

Diese Deckplatte 4 ist lagerseitig, also entgegengesetzt der Magnetkupplung, angeordnet.This cover plate 4 is arranged on the bearing side, that is to say opposite to the magnetic coupling.

Das Gehäusemittelteil 5 weist einen Pumpenraum 6 auf, in dem im Beispielsfalle zwei Pumpenräder 7 und 8 angeordnet sind. Hierbei handelt es sich bei dem Pumpenrad 7 um das treibende Pumpenrad, während das Pumpenrad 8 angetrieben ist. Hierzu steht das Pumpenrad 8 mit dem Pumpenrad 7 in Eingriff.The middle housing section 5 has a pump chamber 6, in which two pump wheels 7 and 8 are arranged in the example. The pump wheel 7 is the driving pump wheel, while the pump wheel 8 is driven. For this purpose, the pump wheel 8 is engaged with the pump wheel 7.

Auf dem Pumpengehäuse 2 der erfindungsgemäßen Zahnradpumpe 1 ist weiterhin eine Haube 9 in nicht näher dargestellter Weise befestigt. Im Innenraum 10 der Haube 9 ist ein Magnet 11 angeordnet, der einen Teil einer nicht näher dargestellten Magnetkupplung zum Übertragen der Antriebskräfte für die Zahnradpumpe 1 bildet.On the pump housing 2 of the gear pump 1 according to the invention, a hood 9 is further fastened in a manner not shown. In the interior 10 of the hood 9, a magnet 11 is arranged, which forms part of a magnetic coupling, not shown, for transmitting the driving forces for the gear pump 1.

Die Pumpenräder 7 und 8 sind erfindungsgemäß auf je einem feststehenden Achszapfen 12 bzw. 13 angeordnet. Hierzu sind die Achszapfen 12 und 13 in entsprechenden Führungsausnehmungen 14 bzw. 15 der Deckplatte 4 befestigt, wozu im Beispielsfalle eine Klebung verwendet wurde. Als geeigneter Werkstoff für die Achszapfen 12 und 13 hat sich beispielsweise V4A-Stahl erwiesen, während als Verbindungsmittel mit der Deckplatte 4 beispielsweise ein Kleber mit der Bezeichnung Loctite 648® geeignet ist. Mittels dieser Befestigung können die Achszapfen 12 und 13 exakt geführt im Pumpengehäuse 2 angeordnet werden, ohne daß weitere Führüngsausnehmungen oder ähnliches erforderlich sind. Daraus ergibt sich der Vorteil, daß zusätzliche Führungsausnehmungen in der Grundplatte 3 entbehrlich sind, was deren Herstellungsaufwand erheblich vermindert.According to the invention, the pump wheels 7 and 8 are each arranged on a fixed axle journal 12 or 13. For this purpose, the axle journals 12 and 13 are fastened in corresponding guide recesses 14 and 15 of the cover plate 4, for which purpose an adhesive was used in the example. V4A steel, for example, has proven to be a suitable material for the axle journals 12 and 13, while an adhesive with the name Loctite 648®, for example, is suitable as a connecting means with the cover plate 4. By means of this fastening, the axle journals 12 and 13 can be arranged in the pump housing 2 in an exactly guided manner, without further guide recesses or the like being necessary. This has the advantage that additional guide recesses in the base plate 3 can be dispensed with, which considerably reduces their production outlay.

Als besonders geeigneter Werkstoff für die Pumpenräder 7 und 8 hat sich Polytetrafluoräthylen-Graphit (Teflon-Graphit) erwiesen, da dieser Werkstoff besonders gute Laufeigenschaften aufweist, so daß ein Auftreten von Verschleiß zwischen den Pumpenrädern 7 und 8 und den zugeordneten Achszapfen 12 bzw. 13 nicht oder in vernachlässigbarem Ausmaß auftritt. Weiterhin ist der genannte Werkstoff für die Pumpenräder 7 und 8 resistent gegen alle üblichen Medien, die insbesondere im medizinischen Bereich wie beispielsweise bei der Dialyse von Zahnradpumpen gefördert werden müssen, bzw. zu deren Reinigung herangezogen werden.Polytetrafluoroethylene graphite (Teflon graphite) has proven to be a particularly suitable material for the pump wheels 7 and 8, since this material has particularly good running properties, so that wear occurs between the pump wheels 7 and 8 and the associated axle journals 12 and 13, respectively does not occur or occurs to a negligible extent. Furthermore, the material mentioned for the pump wheels 7 and 8 is resistant to all the usual media which have to be conveyed, in particular in the medical field, for example in the dialysis of gear pumps, or are used for cleaning them.

Um die ohnehin schon guten Laufeigenschaften und insbesondere das Betriebsgeräusch der erfindungsgemäßen Zahnradpumpe 1 weiter zu verbessern, können die Pumpenräder 7 und 8 mit einer Schrägverzahnung versehen werden, wozu das treibende Pumpenrad 7 beispielsweise 6° links schrägverzahnt sein kann, während das getriebene Pumpenrad 8 entsprechend 6° rechts schrägverzahnt sein kann.In order to further improve the already good running properties and in particular the operating noise of the gear pump 1 according to the invention, the pump wheels 7 and 8 can be provided with helical teeth, for which purpose the driving pump wheel 7 can be helically toothed, for example, 6 ° to the left, while the driven pump wheel 8 corresponds to FIG. 6 ° can be helically toothed on the right.

Wie weiterhin aus Fig. 1 ersichtlich ist, ist das treibende Pumpenrad 7 mit einer Welle 16 verbunden, die erfindungsgemäß als Hohlwelle ausgebildet ist. Im Beispielsfalle ist die Welle 16 einstückig mit dem Pumpenrad 7 verbunden und besteht aus demselben Werkstoff. Wie auch aus Fig. 2 hervorgeht, ergibt die einstückige Ausbildung des Pumpenrades 7 und der Welle 16 eine kompakte und stabile Baueinheit, die auch zur Übertragung großer Drehmomente geeignet ist. Die im Beispielsfalle veranschaulichte einstückige Bauweise von Pumpenrad 7 und Welle 16 kann jedoch im Bedarfsfall auch durch eine andere Verbindung zwischen den genannten Bauteilen ersetzt werden, wozu beispielsweise eine Stiftverbindung geeignet ist.As can also be seen from FIG. 1, the driving pump wheel 7 is connected to a shaft 16, which according to the invention is designed as a hollow shaft. In the example, the shaft 16 is integrally connected to the pump wheel 7 and consists of the same material. As can also be seen from FIG. 2, the one-piece design of the pump wheel 7 and the shaft 16 results in a compact and stable structural unit which is also suitable for the transmission of high torques. The one-piece construction of pump wheel 7 and shaft 16 illustrated in the example case can, however, also be replaced by another connection between the named components if necessary, for which purpose a pin connection is suitable, for example.

Wie weiterhin aus Fig. 2 ersichtlich ist, weisen das Pumpenrad 7 und die als Hohlwelle ausgebildete Welle 16 jeweils eine Durchgangsausnehmung 17 bzw. 18 auf, die im Falle der einstückigen Bauweise eine einzige zusammenhängende Durchgangsausnehmung bilden. An der dem Pumpenrad 7 abgewandten Seite weist die Welle 16 eine Riegelausnehmung 19 auf, die einen sich in Axialrichtung der Welle erstreckenden Bereich 20 und einen sich in Radialrichtung der Welle 16 erstreckenden Bereich 21 auweist. Wie aus Fig. 3 ersichtlich ist, ist auf der der Riegelausnehmung 19 diametral gegenüberliegenden Seite der Welle 16 eine weitere Riegelausnehmung 22 angeordnet, die entsprechend der Ausbildung der Riegelausnehmung 19 ausgebildet ist, wobei sich jedoch die radialen Bereiche 21 und 23 der Riegelausnehmungen 19 bzw. 22 gemäß der in Fig. 3 gewählten Darstellung einmal nach oben bzw. einmal nach unten erstrecken, also zum Mittelpunkt der Welle 16 symmetrisch angeordnet sind.As can furthermore be seen from FIG. 2, the pump wheel 7 and the shaft 16 designed as a hollow shaft each have a passage recess 17 or 18, which in the case of the one-piece construction form a single continuous passage recess. On the side facing away from the impeller 7, the shaft 16 has a locking recess 19 which has an area 20 which extends in the axial direction of the shaft and an area 21 which extends in the radial direction of the shaft 16. As can be seen from FIG. 3, a further locking recess 22 is arranged on the side of the shaft 16 diametrically opposite the locking recess 19, which is designed in accordance with the configuration of the locking recess 19, but the radial regions 21 and 23 of the locking recesses 19 and 22 as shown in FIG. 3, extend once upwards or downwards once, that is to say are arranged symmetrically to the center of the shaft 16.

Wie Fig. 4 verdeutlicht, ist der Magnet 11 auf einer Nabe 24 angeordnet, die eine im Beispielsfalle zylindrische Hülse 25 mit einer inneren Ausnehmung 26 und einen an einem Ende der Hülse 25 angeordneten kreisringförmigen Flansch 27 aufweist. Der kreisringförmige Flansch 27 weist eine Innenausnehmung 28 mit einem Durchmesser auf, der dem der Innenausnehmung der Hülse 25 entspricht. Die Hülse 25 ist weiterhin mit zwei sich in Radialrichtung gegenüberstehenden Ausnehmungen 29 und 30 versehen, in denen Riegelstifte 31 bzw. 32 beispielsweise mittels einer Klebung befestigt sind. Der Magnet 11 selbst ist auf dem Außenumfang der Hülse 25 angeordnet und kann hierzu ebenfalls mittels einer Klebung auf der Hülse 25 befestigt werden.As illustrated in FIG. 4, the magnet 11 is arranged on a hub 24, which in the example has a cylindrical sleeve 25 with an inner recess 26 and an annular flange 27 arranged at one end of the sleeve 25. The annular flange 27 has an inner recess 28 with a diameter which corresponds to that of the inner recess of the sleeve 25. The sleeve 25 is further provided with two radially opposite recesses 29 and 30, in which locking pins 31 and 32 are fastened, for example by means of an adhesive. The magnet 11 itself is arranged on the outer circumference of the sleeve 25 and can also be attached to the sleeve 25 by means of an adhesive.

Wie wiederum aus Fig. 1 ersichtlich ist, sind das Pumpenrad 7 und die mit diesem verbundene Welle 16 auf dem Achszapfen 12 angeordnet, wobei sich die Welle 16 über ihre gesamte Länge auf dem Achszapfen 12 abstützt, so daß trotz des Kunststoff-Werkstoffes für die Welle 16 keine Durchbiegungen zu befürchten sind. Für den Durchtritt der Welle 16 durch die Grundplatte 3 und eines Anschlußflansches 33 der Haube 9 weisen diese Durchtrittsausnehmungen 34 bzw. 35 auf. Wie weiterhin Fig. 1 zeigt, ist die Nabe 24 mit dem auf ihr befestigten Magneten 11 im Beispielsfalle auf dem in den Raum 10 der Haube 9 ragenden Bereich der Welle 16 angeordnet, wobei die Riegelstifte 31 und 32 in die entsprechenden Riegelausnehmungen 19 bzw. 22 eingreifen. Bei der dargestellten Ausführungsform bilden die Riegelausnehmungen 19 und 23 und die Riegelstifte 31 und 32 einen Bajonettverschluß, der seine Riegelwirkung nach einer Drehung der Nabe 24 aufbaut, wobei die Riegelstifte 31 und 32 zunächst in die axialen Bereiche 20 bzw. 36 der Riegelausnehmungen 19 bzw. 22 eingeführt werden. Nach der Drehung der Nabe werden die Riegelstifte 31 und 32 in die radialen Bereiche 21 bzw. 23 der Riegelausnehmungen 19 bzw. 22 eingeführt, wonach die Riegelstifte 31 und 32 die entsprechenden benachbarten Wandbereiche der Welle 16 hintergreifen, so daß ein Heruntergleiten der Nabe 24 von der Hohlwelle 16 verhindert wird.As can be seen again from Fig. 1, the pump wheel 7 and the shaft 16 connected to it are arranged on the journal 12, the shaft 16 being supported over its entire length on the journal 12, so that despite the plastic material for the Wave 16 no deflections are to be feared. For the passage of the shaft 16 through the base plate 3 and a connecting flange 33 of the hood 9, these have passage recesses 34 and 35, respectively. As further shown in FIG. 1, the hub is 24 arranged with the magnet 11 attached to it in the example on the area of the shaft 16 projecting into the space 10 of the hood 9, the locking pins 31 and 32 engaging in the corresponding locking recesses 19 and 22, respectively. In the illustrated embodiment, the locking recesses 19 and 23 and the locking pins 31 and 32 form a bayonet lock, which builds up its locking action after rotation of the hub 24, the locking pins 31 and 32 initially in the axial regions 20 and 36 of the locking recesses 19 and 22 will be introduced. After rotation of the hub, the locking pins 31 and 32 are inserted into the radial areas 21 and 23 of the locking recesses 19 and 22, after which the locking pins 31 and 32 engage behind the corresponding adjacent wall areas of the shaft 16, so that the hub 24 slides off the hollow shaft 16 is prevented.

Zur Montage der zuvor beschriebenen Zahnradpumpe 1 müssen somit vor der Anordnung der Nabe 24 auf der Welle 16 lediglich die Achszapfen 12 und 13 in der Deckplatte 4 des Pumpengehäuses 2 befestigt werden, wonach die Pumpenräder 7 und 8 auf die Achszapfen 12 bzw. 13 aufgesteckt werden können. Im Zuge des Anordnens des Pumpenrades 7 wird die mit diesem verbundene Welle 16 ebenfalls auf dem Achszapfen 12 angeordnet, wonach die Nabe 24 mit dem Magneten 11 in der zuvor beschriebenen Weise auf der Welle 16 gesichert wird. Sämtliche andere Montageschritte zur endgültigen Verbindung der Deckplatte 4, der Grundplatte 3 und des Gehäusemittelstückes 6 sowie der Befestigung der Haube 9 auf dem Pumpengehäuse 2 können in üblicher Weise durchgeführt werden.To assemble the gear pump 1 described above, only the journals 12 and 13 need to be fastened in the cover plate 4 of the pump housing 2 before the hub 24 is arranged on the shaft 16, after which the pump wheels 7 and 8 are pushed onto the journals 12 and 13, respectively can. In the course of arranging the pump wheel 7, the shaft 16 connected to it is also arranged on the axle journal 12, after which the hub 24 is secured on the shaft 16 with the magnet 11 in the manner described above. All other assembly steps for the final connection of the cover plate 4, the base plate 3 and the housing center piece 6 and the fastening of the hood 9 on the pump housing 2 can be carried out in a conventional manner.

Die zuvor beschriebenen Montageschritte zeigen, daß die erfindungsgemäße Zahnradpumpe 1 auf äußerst günstige und schnelle Weise zu montieren ist und daß aufgrund des Vorsehens zweier feststehender Achszapfen 12 und 13 eine Reihe von aufwendigen Fertigungs- und Montageschritten wegfallen, wie sie bei Zahnradpumpen mit sich drehenden Wellen für die Pumpenräder 7 und 8 erforderlich wären. Andererseits ist bei der erfindungsgemäßen Zahnradpumpe 1 trotzdem auf äußerst einfache Weise die Antriebsverbindung zwischen dem Magneten 11 und dem treibenden Pumpenrad 7 mittels der als Hohlwelle ausgebildeten Welle 16 gewährleistet, wobei trotz deren Ausbildung aus Kunststoff eine genügend große Stabilität erreicht wird, da die Welle 16 über ihre gesamte Länge auf dem Achszapfen 12 gelagert ist. Andererseits wird dadurch der Verschleiß nicht erhöht, da die Welle 16 ebenso wie die Pumpenräder 7 und 8 aus einem verschleißfesten Kunststoff mit sehr guten Laufeigenschaften gefertigt werden kann, der auch gegenüber allen insbesondere im Medizinbereich üblichen Medien widerstandsfähig ist.The assembly steps described above show that the gear pump 1 according to the invention can be assembled in an extremely inexpensive and quick manner and that, owing to the provision of two fixed axle journals 12 and 13, a number of complex manufacturing and assembly steps are omitted, as is the case with gear pumps with rotating shafts the pump wheels 7 and 8 would be required. On the other hand, in the gear pump 1 according to the invention, the drive connection between the magnet 11 and the driving pump wheel 7 is nevertheless ensured in an extremely simple manner by means of the shaft 16 designed as a hollow shaft, with a sufficiently high stability being achieved despite its plastic construction, since the shaft 16 is over their entire length is supported on the journal 12. On the other hand, this does not increase the wear, since the shaft 16, like the pump wheels 7 and 8, can be made of a wear-resistant plastic with very good running properties, which is also resistant to all media customary in particular in the medical field.

Claims (10)

1. Gear pump comprising a pump housing (2) having a base plate (3) at the driving side, a cover plate (4) at the bearing side and a housing center portion (5) which is disposed therebetween and in which at least two pump wheels (7, 8) are disposed, one of which drives and at least a further of which is driven, the driven pump wheel (8) consisting of plastic and rotating with its bearing opening to form a plastic-metal antifrictional pairing directly on a stationary journal (13) of metal which is mounted in the pump housing (2), the driving pump wheel (7), too, consisting of plastic and being disposed, too, on a stationary journal (12) of metal which is mounted in the pump housing (2), the driving pump wheel (7) like the driven pump wheel (8) forming a plastic-metal antifrictional pairing with the surface of the journal (12, 13) and the drive member being disposed outside the base plate (3) of the pump housing (2), characterized in that the drive shaft (16) is constructed of plastic and as hollow shaft (16) couplable to a drive member and in a passage recess (34) passes unguided through the base plate (3) and that the journal (12) for bearing the driving pump wheel (7) extends up to the axial region of the drive member and supports the hollow shaft (16) from the inside to form a plastic-metal antifrictional pairing.
2. Gear pump according to claim 1, characterized in that the material of the pump wheels (7, 8) and of the shaft (16) is polytetrafluoroethylene.
3. Gear pump according to claim 1 or 2, characterized in that the driving pump wheel (7) and the shaft (16) constructed as hollow shaft are made integral with each other.
4. Gear pump according to any one of claims 1 to 3, characterized in that the journal (13) of the driven pump wheel (8) is guided only in the cover plate (4).
5. Gear pump according to any one of claims 1 to 4, characterized in that the stationary journals (12, 13) are adhered into the cover plate (4).
6. Gear pump according to any one of claims 1 to 5, characterized in that the drive member is embodied as magnet (11) of a magnet coupling and that the magnet is disposed on a hub (24) which is secured to the hollow shaft (16).
7. Gear pump according to claim 6, characterized in that the magnet (11) is adhered to the hub (24).
8. Gear pump according to claim 6 or 7, characterized in that the hub (24) is provided with a recess (26) whose inner diameter is adapted to the outer diameter of the shaft (16) constructed as hollow shaft.
9. Gear pump according to claim 8, characterized in that at least one locking pin (31, 32) projects radially inwardly into the recess (26) of the hub (24) and engages in a matching locking recess (19, 22) of the hollow shaft (16).
10. Gear pump according to claim 9, characterized in that the connection between hub (24) and shaft (16) is constructed as a bayonet fastener and that the hub (24) is disposed on the shaft (16).
EP84113140A 1983-11-10 1984-10-31 Gear pump, particularly for medical purposes Expired EP0147567B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3340748A DE3340748C2 (en) 1983-11-10 1983-11-10 Gear pumps, in particular for medical purposes
DE3340748 1983-11-10

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EP0147567A2 EP0147567A2 (en) 1985-07-10
EP0147567A3 EP0147567A3 (en) 1986-01-08
EP0147567B1 true EP0147567B1 (en) 1988-08-31

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DE (2) DE3340748C2 (en)

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GB638936A (en) * 1946-11-12 1950-06-21 Sigma Improvements in gearing applicable to gear pumps
US2672823A (en) * 1948-01-12 1954-03-23 Waterous Co Rotary pump
FR1139203A (en) * 1952-01-15 1957-06-26 Gear pump
GB828159A (en) * 1955-07-12 1960-02-17 Straumann Inst Ag Improvements in bearings for movable parts which are subject to friction
FR1194511A (en) * 1958-03-05 1959-11-10 Open casing powder pump
US3010733A (en) * 1959-09-24 1961-11-28 Jamco Inc Idler arm bearing and assembly
FR1299342A (en) * 1961-09-04 1962-07-20 Coy Mfg Company Gear pump
GB1002766A (en) * 1961-09-05 1965-08-25 Coy Mfg Company Improvements in gear pumps
US3240095A (en) * 1962-03-05 1966-03-15 Steinway & Sons Piano action bushing assembly
US3283358A (en) * 1964-09-16 1966-11-08 Richard S Merriam Heavy duty caster
FR1593463A (en) * 1967-12-04 1970-05-25
US3716306A (en) * 1971-03-31 1973-02-13 Micropump Corp Gear pump construction
US4065235A (en) * 1976-06-01 1977-12-27 Tuthill Pump Company Gear pump
DE3045192C2 (en) * 1980-12-01 1983-10-27 Fresenius AG, 6380 Bad Homburg Gear pump

Also Published As

Publication number Publication date
EP0147567A3 (en) 1986-01-08
DE3340748C2 (en) 1986-09-25
DE3473785D1 (en) 1988-10-06
US4583924A (en) 1986-04-22
DE3340748A1 (en) 1985-05-30
EP0147567A2 (en) 1985-07-10

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