EP0448941B1 - Stator for an eccentric screw pump - Google Patents

Stator for an eccentric screw pump Download PDF

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Publication number
EP0448941B1
EP0448941B1 EP91101831A EP91101831A EP0448941B1 EP 0448941 B1 EP0448941 B1 EP 0448941B1 EP 91101831 A EP91101831 A EP 91101831A EP 91101831 A EP91101831 A EP 91101831A EP 0448941 B1 EP0448941 B1 EP 0448941B1
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EP
European Patent Office
Prior art keywords
stator
thread
sleeve
profile
rubber
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EP91101831A
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German (de)
French (fr)
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EP0448941A3 (en
EP0448941A2 (en
Inventor
Heinz Gruber
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GD-ANKER GRUBER-DUEBEL-ANKER GMBH
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Gd-Anker Gruber-Duebel-Anker GmbH
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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04CROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C2/00Rotary-piston machines or pumps
    • F04C2/08Rotary-piston machines or pumps of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing
    • F04C2/10Rotary-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
    • F04C2/107Rotary-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 with helical teeth
    • F04C2/1071Rotary-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 with helical teeth the inner and outer member having a different number of threads and one of the two being made of elastic materials, e.g. Moineau type
    • F04C2/1073Rotary-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 with helical teeth the inner and outer member having a different number of threads and one of the two being made of elastic materials, e.g. Moineau type where one member is stationary while the other member rotates and orbits
    • F04C2/1075Construction of the stationary member

Definitions

  • the invention relates to stators for eccentric screw pumps according to the preamble of claim 1.
  • Eccentric screw pumps are known in manifold forms and serve to convey, for example, solid-liquid mixtures such as mortar, sludge or the like. They consist of a stator, which on the inside carries a thread-like profile made of a rubber-elastic material, in which a rotor made of steel, which also has a thread-like profile on the outside, rotates eccentrically. Between the threaded profiles of the stator and rotor, mutually sealed conveying spaces for the medium to be conveyed are formed, which are moved during the rotation of the rotor in the conveying direction during this movement not their volume, but their shape and location are constantly changing.
  • the pressures or delivery heights achievable on the outlet side depend essentially on the quality of the seal between the named delivery rooms and thus, inter alia, on the rigidity or dimensional stability of the rubber profile of the stator.
  • the latter is usually set via a certain preload, ie diameter difference between the rotor and the stator.
  • a comparatively soft rubber material in the stator profile is considered to be more wear-resistant than a relatively harder one - the former, however, requires much higher preloads to achieve the same initial pressures, so that after rubber is considered an incompressible material, comparatively strong deformations of the stator profile would result.
  • Stators for eccentric screw pumps usually consist of a cylindrical metallic jacket into which an insert made of a rubber material is introduced by means of a spraying process which, on the inside, for example, has the shape of a two-start thread profile intended for cooperation with the rotor.
  • the expected shrinkage in rubber materials depends on the respective wall thickness of the profile, so that with a view to achieving low manufacturing tolerances, special additional measures are required in order to maintain the stated tolerances despite the locally different wall thicknesses that can be traced back to the thread profile mentioned.
  • DE-PS 33 04 751 proposes continuously reducing the effective internal dimensions of the stator from its suction side to its pressure side, so that at a - seen in the axial direction - the same radial dimensions on the pressure side, the greatest preload is available. In this way, a reduction in the drive torque can be achieved.
  • the wall thickness-dependent FR-1 592 149 proposes an eccentric screw pump, the stator of which is characterized by a metallic jacket which is either deformed overall in the manner of a thread or at least has a thread-like profile on the inside, so that it is part of the rubber-elastic insert profile same wall thicknesses - seen over the entire length of the stator - are adjustable.
  • the shrinkage of the rubber material which can be traced back to the uniform wall thickness, considerably simplifies the manufacturing process.
  • stator length is designed to result in the aforementioned thin, uniform layer thicknesses of the rubber material, whereas the remaining remaining part of the stator is designed in the conventional sense.
  • a conventional insert part is thus arranged, which does not interact with a thread-like profile of the jacket, so that the jacket in this section is smooth-walled cylindrical.
  • the stator according to the invention is characterized by a significant saving in the relatively expensive rubber material.
  • the construction according to the invention also makes a contribution to waste disposal.
  • the small layer thicknesses of the rubber insert result in correspondingly small deformation paths, which, in conjunction with the corresponding design of the casing, results in a strong stiffening of a rubber profile even with comparatively small deformation paths, so that there is a correspondingly high resistance to pressure-side stresses.
  • FIG. 1 denotes the steel jacket of a stator, the contour of which is deformed, for example, in the manner of a two-start high-helix thread.
  • the thread profile can be created in any way.
  • the jacket 1 carries on its inside an insert part 2 made of a rubber-elastic material, which is in a preferably non-detachable connection to the inside surface of the jacket, for example vulcanized to the latter.
  • the insert 2 is dimensioned such that the entire inner surface of the jacket 1 is covered with a uniform layer thickness 3.
  • the result on the inside of the jacket 1 is a contour consisting of the rubber-elastic material in the manner of a two-start thread, which can be used as a pump stator.
  • the layer thickness 3 should be at least 5 mm with an acceptable wear of 2 mm. This comparatively small layer thickness is associated with the profiled design of the jacket 1 a number of advantageous effects.
  • the output pressure that can be achieved with eccentric screw pumps and thus their front height depends crucially on the quality of the sealing of the delivery spaces for the respective medium that form between the thread profiles of the rotor and stator.
  • This seal is usually produced by a certain pre-tension between the rotor made of steel and the rubber-elastic material of the stator windings and results in a certain deformation of the stator profile in the area of the seals of the mentioned delivery spaces. The purpose of this deformation is to increase the resistance to deformation due to the stresses that occur on the pressure side.
  • Fig. 2 shows a stator with a smooth cylindrical jacket 4, which in turn consists of steel and serves to receive an insert 5 made of a rubber-elastic material.
  • At 6 is a system of turns Designated from steel wires, which are adapted to the shape of the turns of the insert 5, thus for example form the shape of a two-start high-helix thread and which are welded to the jacket 4 at one or both ends, as indicated at points 7.
  • the turns 6 are completely embedded in the rubber-elastic material, in such a way that, based on the inside of the jacket 5, there are largely uniform layer thicknesses 8 of the rubber material.
  • the windings 6 consist of steel wires of circular cross section.
  • the cross-sectional shape of the steel wires can of course also be adapted to the cross-sectional shape of the individual threads of the thread profile in order to further even out the layer thickness of the rubber. It can be seen that due to the complete embedding of the turns 20 in the rubber-elastic material, corrosion problems are avoided.
  • the insert 5 is in the rest of the jacket in preferably non-detachable connection and is vulcanized, for example.
  • the advantages resulting from the uniform or approximately uniform layer thickness of the rubber material correspond to those of the exemplary embodiment according to FIG. 1, so that reference is made to the statements made there.
  • Fig. 3 shows a further embodiment of a pump stator, consisting of a smooth cylindrical jacket 4 and an insert part 9 consisting of a rubber-elastic material, which can be divided into two sections, namely a first section, with a system of windings 10 consisting of steel wire is provided and a second section that shows no windings or other reinforcements that are functionally comparable with these.
  • the ends of the turns 10 are in turn welded to the jacket 4, as indicated at points 11.
  • the connection of the insert part 9 to the jacket 4 is again carried out in the same manner as in the exemplary embodiments described above and, like in FIG. 2, the aim is to achieve a layer thickness of the rubber material that is as uniform as possible by introducing the windings 10 in this section of the stator.
  • the pre-tension is lower due to the greater layer thicknesses there and thus greater deformability of the rubber material, which is not problematic, however, since there are only slight pressure differences in this area between the individual delivery rooms and the quality of the sealing of the delivery rooms mentioned in this section only is of minor importance. Since the high compressive strength is thus restricted to the area of the stator, in which it is important with regard to the required sealing and thus the achievable delivery head, this is also the case in the operation of the Eccentric screw pump torque significantly reduced compared to such an embodiment, in which a uniform preload is set over the entire length.
  • the section of the pump stator which is equipped with steel wire reinforcements or windings in the sense of the invention can, based on the length of the entire stator, make up a portion of approximately 50%.
  • non-tensionable stators are used, so that their practical handling is very simple, in particular on the construction site.

Abstract

The stator for an eccentric scroll pump has a thread-like profile on the inside and a rubber-elastic insert (2) carried on a metallic cover (1). Part of the cover is provided on the inner side with a thread-like profile and another part has a smooth cylindrical shape which amounts to up to 50 per cent of the length of the stator.

Description

Die Erfindung bezieht sich auf Statoren für Exzenterschneckenpumpen entsprechend dem Oberbegriff des Anspruchs 1.The invention relates to stators for eccentric screw pumps according to the preamble of claim 1.

Exzenterschneckenpumpen sind in mannigfacher Form bekannt und dienen der Förderung beispielsweise von Feststoff-Flüssigkeits-Gemischen wie z.B. Mörtel, Schlämmen oder dergleichen. Sie bestehen aus einem Stator, der innenseitig ein aus einem gummielastischen Werkstoff ausgebildetes gewindeartiges Profil trägt, in dem ein aus Stahl bestehender, außenseitig ebenfalls ein gewindeartiges Profil aufweisender Rotor exzentrisch rotiert. Zwischen den Gewindeprofilen von Stator und Rotor werden voneinander abgedichtete Förderräume für das zu fördende Medium gebildet, die während der Drehung des Rotors in Förderrichtung bewegt werden, während dieser Bewegung zwar nicht ihr Volumen, jedoch ihre Gestalt und Lage laufend ändern. Die ausgangsseitig erreichbaren Drücke bzw. Förderhöhen hängen im wesentlichen von der Qualität der Abdichtung zwischen den genannten Förderräumen und damit unter anderem von der Steifigkeit bzw. Formbeständigkeit des Gummiprofils des Stators ab. Letzteres wird üblicherweise über eine gewisse Vorspannung, d.h. Durchmesserdifferenz zwischen Rotor und Stator eingestellt. Nun gilt ein vergleichsweise weicher Gummiwerkstoff im Rahmen des Statorprofils als verschleißfester als ein relativ härterer - der erstere erfordert jedoch zur Erzielung gleicher Ausgangsdrücke wesentlich höhere Vorspannungen, so daß sich, nachdem Gummi als ein inkompressibler Werkstoff anzusehen ist, vergleichsweise starke Verformungen des Statorprofils ergeben würden.Eccentric screw pumps are known in manifold forms and serve to convey, for example, solid-liquid mixtures such as mortar, sludge or the like. They consist of a stator, which on the inside carries a thread-like profile made of a rubber-elastic material, in which a rotor made of steel, which also has a thread-like profile on the outside, rotates eccentrically. Between the threaded profiles of the stator and rotor, mutually sealed conveying spaces for the medium to be conveyed are formed, which are moved during the rotation of the rotor in the conveying direction during this movement not their volume, but their shape and location are constantly changing. The pressures or delivery heights achievable on the outlet side depend essentially on the quality of the seal between the named delivery rooms and thus, inter alia, on the rigidity or dimensional stability of the rubber profile of the stator. The latter is usually set via a certain preload, ie diameter difference between the rotor and the stator. Now a comparatively soft rubber material in the stator profile is considered to be more wear-resistant than a relatively harder one - the former, however, requires much higher preloads to achieve the same initial pressures, so that after rubber is considered an incompressible material, comparatively strong deformations of the stator profile would result.

Einer Erhöhung der Vorspannung zwecks Erhöhung des Ausgangsdrucks sind Grenzen gesetzt, und zwar sowohl mit Hinblick auf das erforderliche Antriebsdrehmoment als auch auf den sich einstellenden Verschleiß. Dieser Verschleiß wirkt sich unter anderem bei dem Stahlrotor aus, der - druckseitig beginnend und in Richtung auf die Saugseite hin fortschreitend - abgetragen wird und in seinen Ausmaßen schließlich eine sich global auf die Druckseite hin konisch verjüngende Gestalt erhält. Dieses allmähliche Materialabtragen hat eine kontinuierlich sinkende Vorspannung sowie Dichtwirkung zwischen den genannten Förderräumen und somit eine Verringerung der erreichbaren Förderhöhe zur Folge. Leistungssteigerungen durch Drehzahlerhöhung sind mit Hinblick auf den zu erwartenden Verschleiß sowie den Energiebedarf ebenfalls nicht sinnvoll. Statoren für Exzenterschneckenpumpen bestehen üblicherweise aus einem zylindrischen metallischen Mantel, in den über einen Spritzprozeß ein aus einem Gummiwerkstoff bestehendes Einsatzteil eingebracht wird, welches innenseitig beispielsweise die Form eines zweigängigen, zum Zusammenwirken mit dem Rotor bestimmtes Gewindeprofil aufweist. Bekanntlich ist bei Gummiwerkstoffen das zu erwartende Schwundmaß abhängig von der jeweiligen Wandungsdicke des Profils, so daß mit Hinblick auf die Erzielung geringer Fertigungstoleranzen besondere Zusatzmaßnahmen erforderlich sind, um trotz der, auf das genannte Gewindeprofil zurückführbaren, örtlich unterschiedlichen Wandungsdicken die genannten Toleranzen einzuhalten.There are limits to increasing the preload in order to increase the outlet pressure, both with regard to the required drive torque and the wear that occurs. This wear affects, among other things, the steel rotor, which is removed - starting on the pressure side and progressing towards the suction side - and finally receives a shape that tapers globally towards the pressure side. This gradual removal of material results in a continuously decreasing pre-tension and sealing effect between the mentioned conveying spaces and thus a reduction in the achievable delivery head. Performance increases by increasing the speed are also not sensible with regard to the wear to be expected and the energy requirement. Stators for eccentric screw pumps usually consist of a cylindrical metallic jacket into which an insert made of a rubber material is introduced by means of a spraying process which, on the inside, for example, has the shape of a two-start thread profile intended for cooperation with the rotor. As is known, the expected shrinkage in rubber materials depends on the respective wall thickness of the profile, so that with a view to achieving low manufacturing tolerances, special additional measures are required in order to maintain the stated tolerances despite the locally different wall thicknesses that can be traced back to the thread profile mentioned.

Aus der DE-AS 15 53 199 ist ein nachspannsparer Stator für eine Exzenterschneckenpumpe bekannt, bei dem das aus einem elastischen Werkstoff bestehende Einsatzteil in einem, in seinem Durchmesser verringerbaren metallischen Mantel angeordnet ist, so daß über eine Durchmesserverringerung ein auftretender Verschleiß in einem gewissen Rahmen ausgleichbar ist. Problematisch ist jedoch die genaue Einstellung der jeweils erforderlichen Vorspannung, welches zumindest bei Baustelleneinsätzen, soweit dies überhaupt möglich ist, einen erheblichen Aufwand bedeutet.From DE-AS 15 53 199 a tension-saving stator for an eccentric screw pump is known, in which the insert made of an elastic material is arranged in a metal jacket that can be reduced in diameter, so that wear and tear occurs within a certain range by reducing the diameter is compensable. The problem, however, is the exact setting of the pretension required in each case, which means, at least in construction site operations, as far as this is possible at all, considerable effort.

Zur Verminderung der durch die Vorspannung zwischen Stator und Rotor veranlaßten Reibungs- und damit Leistungsverluste wird in der DE-PS 33 04 751 vorgeschlagen, die wirksamen Innenabmessungen des Stators ausgehend von dessen Saugseite bis zu dessen Druckseite hin kontinuierlich zu verringern, so daß bei einem - in Achsrichtung gesehen - gleiche radiale Abmessungen aufweisenden Rotor druckseitig die größte Vorspannung zur Verfügung steht. Auf diese Weise läßt sich eine Verringerung des Antriebsmoments erreichen.In order to reduce the friction and thus power losses caused by the pretension between the stator and the rotor, DE-PS 33 04 751 proposes continuously reducing the effective internal dimensions of the stator from its suction side to its pressure side, so that at a - seen in the axial direction - the same radial dimensions on the pressure side, the greatest preload is available. In this way, a reduction in the drive torque can be achieved.

Um herstellungstechnische, auf das wandstärkenabhängige Schwundmaß bei Gummiwerkstoffen zurückführbare Schwierigkeiten zu beheben, wird in der FR-1 592 149 eine Exzenterschneckenpumpe vorgeschlagen, deren Stator durch einen metallischen Mantel charakterisiert ist, der entweder insgesamt gewindeartig verformt ist oder zumindest innenseitig ein gewindeartiges Profil trägt, so daß im Rahmen des gummielastischen Einsatzprofils gleiche Wanddicken - über die gesamte Länge des Stators gesehen - einstellbar sind. Das auf die gleichmäßige Wandstärke zurückführbare Schwundmaß des Gummiwerkstoffs bringt eine erhebliche Vereinfachung des Herstellungsvorgangs mit sich.To manufacturing technology, to the wall thickness-dependent FR-1 592 149 proposes an eccentric screw pump, the stator of which is characterized by a metallic jacket which is either deformed overall in the manner of a thread or at least has a thread-like profile on the inside, so that it is part of the rubber-elastic insert profile same wall thicknesses - seen over the entire length of the stator - are adjustable. The shrinkage of the rubber material, which can be traced back to the uniform wall thickness, considerably simplifies the manufacturing process.

Es ist die Aufgabe der Erfindung, einen gattungsgemäßen Stator für eine Exzenterschneckenpumpe unter Vermeidung der dem Stand der Technik anhaftenden Nachteile in einfacher Weise mit Hinblick auf eine höhere Standzeit, sowie höhere Leistungen bzw. einen verringerten Energieaufwand hin auszugestalten. Gelöst ist diese Aufgabe bei einem gattungsgemäßen Stator durch die Merkmale des Kennzeichnungsteils des Anspruchs 1.It is the object of the invention to design a generic stator for an eccentric screw pump while avoiding the disadvantages inherent in the prior art in a simple manner with a view to a longer service life, as well as higher outputs and reduced energy consumption. In a generic stator, this object is achieved by the features of the characterizing part of claim 1.

Es ist somit lediglich ein Teil der Statorlänge dahingehend ausgebildet, daß sich die genannten geringen gleichmäßigen Schichtdicken des Gummiwerkstoffs ergeben, wohingegen der verbleibende übrige Teil des Stators im herkömmlichen Sinne ausgebildet ist. In diesem letztgenannten Teil ist somit ein herkömmliches Einsatzteil angeordnet, welches nicht mit einem gewindeartigen Profil des Mantels zusammenwirkt, so daß der Mantel in diesem Abschnitt glattwandig zylindrisch ausgebildet ist. Bei einer Verwendung herkömmlicher Stahlrotoren werden auf diese Weise unterschiedliche Verformungsfähigkeiten in den sich ergebenden beiden Abschnitten des Stators erreicht, und zwar derart, daß druckseitig, nämlich im Bereich der geringen gleichmäßigen Schichtdicken stets eine erforderliche hohe Steifigkeit und damit Dichtwirkung zur Verfügung steht. Dieses System kann naturgemäß in vielfältiger Weise ausgestaltet werden. Beispielsweise können durch entsprechende Bemessung des erstgenannten Teils auch mehr als zwei Abschnitte im Verlauf einer Statorlänge bereitgestellt werden, welche sich durch unterschiedliche Verformungsfähigkeiten des Gummiwerkstoffs auszeichnen, und zwar dahingehend, daß sich von der Saugseite zur Druckseite eine stufenweise zunehmende Steifigkeit des Gummiwerkstoffs ergibt. Die jeweiligen Schichtdicken der Einsatzteile können ausgehend von der erforderlichen Vorspannung, der Elastizität des Werkstoffs sowie eines zuzulassenden Verschleißmaßes kleinstmöglich gewählt werden. Da sich die Materialkosten beispielsweise von Rohgummi einerseits und Stahl bzw. Eisen andererseits erheblich unterscheiden, ist der erfindungsgemäße Stator durch eine bedeutende Einsparung an dem relativ teurem Gummiwerkstoff gekennzeichnet. Da verschlissene Statoren stets als Ganzes verworfen werden, eine Rückgewinnung des vorhandenen Gummiwerkstoffs praktisch kaum stattfindet, wird durch die erfindungsgemäße Konstruktion auch ein Beitrag zur Abfallbeseitigung geleistet. Die geringen Schichtdicken des Gummieinsatzes haben entsprechend geringe Verformungswege zur Folge, welches in Verbindung mit der entsprechenden Gestaltung des Mantels bereits bei vergleichsweise geringen Verformungswegen eine starke Versteifung eines Gummiprofils nach sich zieht, so daß sich eine entsprechend hohe Widerstandsfähigkeit gegenüber druckseitigen Beanspruchungen ergibt. Diese Gesichtspunkte gelten in gleichem Maß auch für relativ weiche Gummiwerkstoffe, deren Verformung durch die Profilierung des Mantels bzw. ein System von in diesen eingelegten Windungen ebenfalls behindert wird, so daß sich auch in diesem Fall aufgrund der Inkompressibilität des Gummis eine hohe Versteifung, insbesondere im Bereich der Dichtflächen der eingangs genannten Förderräume ergibt. Bei Einsatz relativ harter Gummiwerkstoffe können somit höchste Ausgangsdrücke erreicht werden.Thus, only part of the stator length is designed to result in the aforementioned thin, uniform layer thicknesses of the rubber material, whereas the remaining remaining part of the stator is designed in the conventional sense. In this latter part, a conventional insert part is thus arranged, which does not interact with a thread-like profile of the jacket, so that the jacket in this section is smooth-walled cylindrical. When using conventional steel rotors, different deformation capacities are achieved in the resulting two sections of the stator, in such a way that namely, in the area of low, uniform layer thicknesses, the required high rigidity and thus sealing effect is always available. This system can of course be designed in a variety of ways. For example, by appropriately dimensioning the first-mentioned part, it is also possible to provide more than two sections over the course of a stator length, which are distinguished by different deformability of the rubber material, to the extent that there is a gradually increasing rigidity of the rubber material from the suction side to the pressure side. The respective layer thicknesses of the insert parts can be chosen as small as possible based on the required pretension, the elasticity of the material and an allowable wear measure. Since the material costs, for example, of raw rubber on the one hand and steel or iron on the other hand differ considerably, the stator according to the invention is characterized by a significant saving in the relatively expensive rubber material. Since worn stators are always discarded as a whole, and there is practically no recovery of the existing rubber material, the construction according to the invention also makes a contribution to waste disposal. The small layer thicknesses of the rubber insert result in correspondingly small deformation paths, which, in conjunction with the corresponding design of the casing, results in a strong stiffening of a rubber profile even with comparatively small deformation paths, so that there is a correspondingly high resistance to pressure-side stresses. These aspects apply equally to relatively soft rubber materials, the deformation of which is also impeded by the profiling of the jacket or a system of windings inserted therein is, so that in this case too, due to the incompressibility of the rubber, there is a high degree of stiffening, in particular in the area of the sealing surfaces of the delivery spaces mentioned at the beginning. When using relatively hard rubber materials, the highest outlet pressures can be achieved.

Die Erfindung wird im folgenden unter Bezugnahme auf die in den Zeichnungen dargestellten Ausführungsbeispiele näher erläutert werden. Es zeigen:

  • Fig. 1 einen erfindungsgemäßen Stator im Axialschnitt;
  • Fig. 2 ein anderes Ausführungsbeispiel eines erfindungsgemäßen Stators im Axialschnitt;
  • Fig. 3 ein weiteres Ausführungsbeispiel eines erfindungsgemäßen Stators im Axialschnitt.
The invention will be explained in more detail below with reference to the exemplary embodiments shown in the drawings. Show it:
  • 1 shows a stator according to the invention in axial section;
  • 2 shows another embodiment of a stator according to the invention in axial section;
  • Fig. 3 shows another embodiment of a stator according to the invention in axial section.

Mit 1 ist in Fig. 1 der aus Stahl bestehende Mantel eines Stators bezeichnet, dessen Kontur beispielsweise nach Art eines zweigängigen Steilgewindes verformt ist. Das Gewindeprofil kann in beliebiger Weise erzeugt werden. Der Mantel 1 trägt auf seiner Innenseite ein aus einem gummielastischen Werkstoff bestehendes Einsatzteil 2, das mit der Innenfläche des Mantels in vorzugsweise unlösbarer Verbindung steht, beispielsweise an diesen anvulkanisiert ist. Das Einsatzteil 2 ist derart bemessen, daß die gesamte Innenfläche des Mantels 1 mit einer gleichmäßigen Schichtdicke 3 überzogen ist. Es ergibt sich somit auf der Innenseite des Mantels 1 eine aus dem gummielastischen Werkstoff bestehende Kontur nach Art eines zweigängigen Gewindes, welche als Pumpenstator einsetzbar ist.1 in FIG. 1 denotes the steel jacket of a stator, the contour of which is deformed, for example, in the manner of a two-start high-helix thread. The thread profile can be created in any way. The jacket 1 carries on its inside an insert part 2 made of a rubber-elastic material, which is in a preferably non-detachable connection to the inside surface of the jacket, for example vulcanized to the latter. The insert 2 is dimensioned such that the entire inner surface of the jacket 1 is covered with a uniform layer thickness 3. The result on the inside of the jacket 1 is a contour consisting of the rubber-elastic material in the manner of a two-start thread, which can be used as a pump stator.

Die Schichtdicke 3 sollte bei einem akzeptierbaren Verschleiß von 2 mm wenigstens 5 mm betragen. Diese vergleichsweise geringe Schichtdicke bringt in Verbindung mit der profilierten Gestaltung des Mantels 1 eine Reihe vorteilhafter Wirkungen hervor.The layer thickness 3 should be at least 5 mm with an acceptable wear of 2 mm. This comparatively small layer thickness is associated with the profiled design of the jacket 1 a number of advantageous effects.

Bekanntlich hängt der bei Exzenterschneckenpumpen erreichbare Ausgangsdruck und damit deren Vorderhöhe entscheidend von der Qualität der Abdichtung der sich zwischen den Gewindeprofilen von Rotor und Stator ausbildenden Förderräume für das jeweilige Medium ab. Diese Abdichtung wird üblicherweise durch eine gewisse Vorspannung zwischen dem aus Stahl bestehenden Rotor und dem gummielastischen Werkstoff der Statorwindungen hergestellt und hat eine gewisse Verformung des Statorprofils im Bereich der Abdichtungen der genannten Förderräume zur Folge. Zweck dieser Verformung ist die Erhöhung des Verformungswiderstands aufgrund der druckseitig auftretenden Beanspruchungen. Durch die erfindungsgemäßen geringen Schichtdicken des gummielastischen Werkstoffs ergeben sich in Verbindung mit den Stützwirkungen des gewindeartig verformten Mantels 1 vergleichsweise geringe Verformungsmöglichkeiten, so daß bei gleicher Druckfestigkeit bzw. gleichem erreichbaren Ausgangsdruck das Ausmaß der Vorspannung zwischen Rotor und Stator geringer bemessen werden kann als bei herkömmlichen Exzenterschneckenpumpen. Versteifend bzw. den Verformungswiderstand erhöhend wirkt sich somit insbesondere die Profilierung des Mantels 1 aus, der dem Innenprofil des Stators über seine gesamte Länge eine gleichmäßige Stützwirkung verleiht.As is known, the output pressure that can be achieved with eccentric screw pumps and thus their front height depends crucially on the quality of the sealing of the delivery spaces for the respective medium that form between the thread profiles of the rotor and stator. This seal is usually produced by a certain pre-tension between the rotor made of steel and the rubber-elastic material of the stator windings and results in a certain deformation of the stator profile in the area of the seals of the mentioned delivery spaces. The purpose of this deformation is to increase the resistance to deformation due to the stresses that occur on the pressure side. Due to the small layer thicknesses of the rubber-elastic material according to the invention, in connection with the supporting effects of the thread-like deformed casing 1, there are comparatively small deformation possibilities, so that the extent of the preload between the rotor and stator can be dimensioned less than with conventional eccentric screw pumps with the same compressive strength or the same achievable output pressure . Stiffening or increasing the resistance to deformation thus has in particular the profiling of the jacket 1, which gives the inner profile of the stator a uniform support effect over its entire length.

Nachdem somit auf konstruktivem Wege die Verformungsmöglichkeiten des Gummiwerkstoffs beschränkt sind, besteht die Möglichkeit, einen an sich verschleißfesteren Weichgummi einzusetzen, ohne - wie an-sonst erforderlich - übermäßig hohe Vorspannkräfte zur Erzielung der nötigen Druckfestigkeit aufbringen zu müssen.Since the deformation possibilities of the rubber material are thus restricted in a constructive way, it is possible to use a soft rubber that is more wear-resistant per se, without having to apply excessively high pretensioning forces to achieve the necessary compressive strength, as is otherwise required.

Die Verwendung eines vergleichsweise harten Gummiwerkstoffs im Rahmen des Statorprofils bringt hingegen die Möglichkeit mit sich, trotz geringer Vorspannkräfte hohe Ausgangsdrücke zu erreichen. Aufgrund der homogenen Schichtdicke auf der Innenseite des Mantels 1 ergibt sich ferner auf einfachstem Wege die Möglichkeit einer im Vergleich zu den bekannten Pumpenstatoren erheblich verbesserten Fertigungsgenauigkeit, da mit einem weitestgehend gleichförmigen Schwundmaß gerechnet werden kann und aufwendige Zusatzmaßnahmen zur Kompensation eines ungleichförmigen Schwundmaßes aufgrund ungleichmäßiger Wandungs- bzw. Schichtdicken des Gummiwerkstoffs entfallen.The use of a comparatively hard rubber material in the frame of the stator profile, on the other hand, offers the possibility of achieving high output pressures despite the low preload forces. Due to the homogeneous layer thickness on the inside of the jacket 1, there is also the simplest possible way of achieving a manufacturing accuracy which is considerably improved compared to the known pump stators, since a largely uniform shrinkage can be expected and complex additional measures to compensate for a non-uniform shrinkage due to uneven wall or layer thicknesses of the rubber material are eliminated.

Die Herstellung eines Pumpenstators entsprechend Fig. 1 kann grundsätzlich in bekannter Weise, jedoch ausgehend von einem entsprechend profilierten Mantel 1 erfolgen, in welchem jeweils unter Verwendung eines außenseitig entsprechend profilierten Kerns die Substanz des gummiartigen Werkstoffs eingespritzt wird. Man erkennt, daß aufgrund der profilierten Gestaltung des Mantels 1 die Verbundwirkung zwischen diesen und dem gummiartigen Werkstoff zusätzlich zu einem Verkleben beziehungsweise Anvulkanisieren durch einen gewissen Formschluß verbessert wird. Es können vergleichsweise geringe Schichtdicken 3 verwendet werden, woraus sich in einfacher Weise neben geringen Maßtoleranzen und ein hoher Verformungswiderstand des Systems aus Einsatzteil 2 und Mantel 1 ergibt.1 can in principle be produced in a known manner, but starting from a correspondingly profiled jacket 1, in which the substance of the rubber-like material is injected using a core which is correspondingly profiled on the outside. It can be seen that, due to the profiled design of the jacket 1, the bond between the latter and the rubber-like material is additionally improved by a certain positive fit, in addition to gluing or vulcanization. Comparatively small layer thicknesses 3 can be used, which results in a simple manner in addition to small dimensional tolerances and a high resistance to deformation of the system from insert 2 and jacket 1.

Fig. 2 zeigt einen Stator mit einem glatten zylindrischen Mantel 4, der wiederum aus Stahl besteht und der Aufnahme eines Einsatzteiles 5 aus einem gummielastischen Werkstoff dient. Mit 6 ist ein System von Windungen aus Stahldrähten bezeichnet, die der Gestalt der Windungen des Einsatzteiles 5 angepaßt sind, somit beispielsweise die Form eines zweigängigen Steilgewindes bilden und die an einem oder auch an beiden stirnseitigen Enden mit dem Mantel 4 verschweißt sind, wie an den Stellen 7 angedeutet ist.Fig. 2 shows a stator with a smooth cylindrical jacket 4, which in turn consists of steel and serves to receive an insert 5 made of a rubber-elastic material. At 6 is a system of turns Designated from steel wires, which are adapted to the shape of the turns of the insert 5, thus for example form the shape of a two-start high-helix thread and which are welded to the jacket 4 at one or both ends, as indicated at points 7.

Die Windungen 6 sind vollständig in den gummielastischen Werkstoff eingebettet, und zwar derart, daß sich bezogen auf die Innenseite des Mantels 5 weitestgehend gleichmäßige Schichtdicken 8 des Gummiwerkstoffs ergeben.The turns 6 are completely embedded in the rubber-elastic material, in such a way that, based on the inside of the jacket 5, there are largely uniform layer thicknesses 8 of the rubber material.

Die Windungen 6 bestehen in dem gezeigten Ausführungsbeispiel aus Stahldrähten von kreisförmigem Querschnitt. Naturgemäß kann die Querschnittsform der Stahldrähte zur noch weitergehenderen Vergleichmäßigung der Schichtdicke des Gummis auch an die Querschnittsgestalt der einzelnen Gewindegänge des Gewindeprofils angepaßt sein. Man erkennt, daß aufgrund der vollständigen Einbettung der Windungen 20 in den gummielastischen Werkstoff Korrosionsprobleme vermieden werden. Das Einsatzteil 5 steht im übrigen mit dem Mantel in vorzugsweise unlösbarer Verbindung und ist beispielsweise anvulkanisiert. Die sich aus der gleichmäßigen bzw. angenähert gleichmäßigen Schichtdicke des Gummiwerkstoffs ergebenden Vorzüge entsprechen denjenigen des Ausführungsbeispiels gemäß Fig. 1, so daß insoweit auf die dortigen Ausführungen Bezug genommen wird.In the exemplary embodiment shown, the windings 6 consist of steel wires of circular cross section. The cross-sectional shape of the steel wires can of course also be adapted to the cross-sectional shape of the individual threads of the thread profile in order to further even out the layer thickness of the rubber. It can be seen that due to the complete embedding of the turns 20 in the rubber-elastic material, corrosion problems are avoided. The insert 5 is in the rest of the jacket in preferably non-detachable connection and is vulcanized, for example. The advantages resulting from the uniform or approximately uniform layer thickness of the rubber material correspond to those of the exemplary embodiment according to FIG. 1, so that reference is made to the statements made there.

Fig. 3 zeigt ein weiteres Ausführungsbeispiel eines Pumpenstators, bestehend aus einem glatten zylindrischen Mantel 4 und einem aus einen gummielastischen Werkstoff bestehenden Einsatzteil 9, welches in zwei Abschnitte unterteilbar ist, nämlich einen ersten Abschnitt, der mit einem System von Windungen 10, bestehend aus Stahldraht versehen ist und einem zweiten Abschnitt, der keinerlei Windungen oder sonstige, mit diesen funktionell vergleichbare Armierungen zeigt. Die Enden der Windungen 10 sind wiederum mit dem Mantel 4 verschweißt, wie an den Stellen 11 angedeutet ist. Die Verbindung des Einsatzteils 9 mit dem Mantel 4 erfolgt wiederum in gleicher Weise wie bei den vorstehend beschriebenen Ausführungsbeispielen und es wird ebenso wie bei Fig. 2 durch die Einbringung der Windungen 10 in diesem Abschnitt des Stators eine möglichst gleichmäßige Schichtdicke des Gummiwerkstoffs angestrebt.Fig. 3 shows a further embodiment of a pump stator, consisting of a smooth cylindrical jacket 4 and an insert part 9 consisting of a rubber-elastic material, which can be divided into two sections, namely a first section, with a system of windings 10 consisting of steel wire is provided and a second section that shows no windings or other reinforcements that are functionally comparable with these. The ends of the turns 10 are in turn welded to the jacket 4, as indicated at points 11. The connection of the insert part 9 to the jacket 4 is again carried out in the same manner as in the exemplary embodiments described above and, like in FIG. 2, the aim is to achieve a layer thickness of the rubber material that is as uniform as possible by introducing the windings 10 in this section of the stator.

Geht man davon aus, daß mit dem Pfeil 12 die Förderrichtung des Stators bezeichnet ist, wird durch dessen Unterteilung in die obengenannten beiden Abschnitte erreicht, daß in dem ersten, mit Windungen versehenen Abschnitt wesentlich geringere Verformungsmöglichkeiten des Gummiwerkstoffs als in dem zweiten Abschnitt bestehen. Druckseitig ergibt sich somit nach Einsetzen eines Rotors eine wesentlich höhere Versteifung und damit Druckfestigkeit des Gummiwerkstoffs und eine gute Abdichtung der einzelnen, sich zwischen den Windungen des Rotors und des Stators ausbildenden Förderräume. Saugseitig fällt hingegen die Vorspannung aufgrund der dort gegebenen größeren Schichtdicken und damit größeren Verformbarkeit des Gummiwerkstoffs geringer aus, welches jedoch unproblematisch ist, da in diesem Bereich zwischen den einzelnen Förderräumen ohnehin nur geringe Druckdifferenzen anstehen und die Qualität der Abdichtung der genannten Förderräume in diesem Abschnitt nur von untergeordneter Bedeutung ist. Indem somit die hohe Druckfestigkeit auf den Bereich des Stators beschränkt ist, in dem diese mit Hinblick auf die erforderliche Abdichtung und damit die erreichbare Förderhöhe von Bedeutung ist, wird gleichzeitig das im Betrieb der Exzenterschneckenpumpe aufzubringende Drehmoment gegenüber einer solchen Ausführungsform, bei der eine gleichmäßige Vorspannung über die gesamte Länge eingestellt wird, merklich verringert.Assuming that the arrow 12 indicates the direction of conveyance of the stator, by dividing the stator into the two sections mentioned above, there is much less possibility of deformation of the rubber material in the first section provided with turns than in the second section. On the pressure side, after inserting a rotor, there is a much higher stiffening and thus pressure resistance of the rubber material and a good seal of the individual delivery spaces that form between the windings of the rotor and the stator. On the suction side, on the other hand, the pre-tension is lower due to the greater layer thicknesses there and thus greater deformability of the rubber material, which is not problematic, however, since there are only slight pressure differences in this area between the individual delivery rooms and the quality of the sealing of the delivery rooms mentioned in this section only is of minor importance. Since the high compressive strength is thus restricted to the area of the stator, in which it is important with regard to the required sealing and thus the achievable delivery head, this is also the case in the operation of the Eccentric screw pump torque significantly reduced compared to such an embodiment, in which a uniform preload is set over the entire length.

Der Abschnitt des Pumpenstators, der im erfindungsgemäßen Sinne mit Stahldrahtarmierungen bzw. -windungen ausgerüstet ist, kann - bezogen auf die Länge des gesamten Stators einen Anteil von etwa 50 % ausmachen.The section of the pump stator which is equipped with steel wire reinforcements or windings in the sense of the invention can, based on the length of the entire stator, make up a portion of approximately 50%.

In allen Ausführungsbeispielen werden nichtspannbare Statoren eingesetzt, so daß sich deren praktische Handhabung insbesondere baustellenseitig sehr einfach gestaltet.In all of the exemplary embodiments, non-tensionable stators are used, so that their practical handling is very simple, in particular on the construction site.

Claims (3)

  1. Stator for an eccentric screw pump, which consists of a metallic sleeve (1) and an insert (2) of elastic rubber material with a thread-like profile arranged on the inside of the sleeve, characterised in that
    - a delivery-side portion of the sleeve (1) likewise has a thread-like profile on the inside or is shaped to be thread-like as a whole, and the insert (2) in this portion of the sleeve (1) is formed by a layer having a uniform thickness (3), and
    - an intake-side portion of the sleeve (1) is a smooth cylinder on the inside.
  2. Stator according to claim 1, characterised in that the internally smooth cylindrical portion constitutes 50% of the length of the stator.
  3. Stator for an eccentric screw pump according to claim 1, characterised in that
    - the sleeve (4) is a smooth cylinder,
    - the insert (9) is provided in a delivery-side portion with a system of metallic wound turns (10) enclosed fully within the elastic rubber material while retaining a uniform layer thickness with the cross-sectional shape of the wound turns being matched to the cross-sectional contour of the individual thread courses of the threaded profile, and
    - the system of wound turns (10) is connected at least partially with the inside of the sleeve (4).
EP91101831A 1990-03-01 1991-02-09 Stator for an eccentric screw pump Expired - Lifetime EP0448941B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE4006339A DE4006339C2 (en) 1990-03-01 1990-03-01 Stator for an eccentric screw pump
DE4006339 1990-03-01

Publications (3)

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EP0448941A2 EP0448941A2 (en) 1991-10-02
EP0448941A3 EP0448941A3 (en) 1992-06-24
EP0448941B1 true EP0448941B1 (en) 1996-05-15

Family

ID=6401145

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Application Number Title Priority Date Filing Date
EP91101831A Expired - Lifetime EP0448941B1 (en) 1990-03-01 1991-02-09 Stator for an eccentric screw pump

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US (1) US5145342A (en)
EP (1) EP0448941B1 (en)
JP (1) JP2950629B2 (en)
AT (1) ATE138160T1 (en)
DE (2) DE4006339C2 (en)

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Also Published As

Publication number Publication date
JP2950629B2 (en) 1999-09-20
US5145342A (en) 1992-09-08
ATE138160T1 (en) 1996-06-15
DE4006339C2 (en) 1994-08-04
DE4006339C1 (en) 1991-08-01
EP0448941A3 (en) 1992-06-24
DE59107796D1 (en) 1996-06-20
JPH0742679A (en) 1995-02-10
EP0448941A2 (en) 1991-10-02

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