DE102017100540B4 - Cavity Pump - Google Patents

Abstract

Eccentric screw pump with at least
a stator (1) of elastic material,
a rotor (2) rotating in the stator,
a stator jacket (3) surrounding the stator,
a pump housing (4) connected to the stator (1) at a first end,
a connection housing (5) connected to the stator (1) at a second end, the stator (1) having end-side end faces (19) with wall thickness varying over the circumference,
characterized in that in the region of at least one end of the stator, a release spring (16) limiting the elastic stator (1) against expansion or displacement in the axial direction is provided, such that the release lock (16) forms an inlet cross-section deviating from the circular shape into the connecting flange (10 , 11) or in the respective housing (4, 5) is integrated and
the stator (1) is connected to the connecting flange (10, 11) in such a manner that end face regions (19a) with maximum wall thickness bear against the disengagement fuse (16).

Description

The invention relates to an eccentric screw pump having at least one stator made of elastic material, a rotor rotating in the stator, a stator casing surrounding the stator, a pump housing connected to the stator at a first end and a connection housing connected to the stator at a second end Stator has end-side end faces with varying wall thickness over the circumference.

- The pump housing is - depending on the operating direction of the pump - also referred to as a suction housing and it is usually provided with an inlet opening for the medium to be delivered. The connection housing is accordingly also referred to as a discharge nozzle.

In such an eccentric screw pump, the rotor is regularly connected via at least one coupling rod to the drive or a drive shaft. The coupling rod is z. B. connected via a first joint to the rotor and a second joint with the drive shaft or connected to the drive connecting shaft. The stator is connected at its one end to the pump housing or a corresponding flange of the pump housing with its other end to the connector housing or a corresponding flange of this connector housing. In this case, the stator made of elastic material, for. B. made of an elastomer. It may be z. B. be a synthetic rubber or natural rubber or a rubber mixture.

Preferably, the stator is a longitudinally divided stator of at least two Statorteilschalen z. B. stator half shells formed. Furthermore, the stator is preferably exchangeable separately from the stator casing and consequently not fixed and in particular not materially connected to the stator casing. This makes it possible to replace the elastomeric stator separately from the stator shell, without a costly disassembly of the pump is necessary. The stator jacket preferably consists of at least two shroud segments, which form as clamping segments a Statorspannvorrichtung with which the stator can be tensioned in the radial direction against the rotor. In this case, the stator jacket of z. B. three sheath segments or four sheath segments, which form the Statorspannvorrichtung.

An eccentric screw pump of this kind is z. B. from the WO 2009/024 279 A1 , of the DE 10 2008 021 920 A1 or the DE 10 2014 112 550 B4 known.

Such eccentric screw pumps have basically proven themselves in practice, but they are capable of further development.

Furthermore, the describes DE 694 013 69 T2 an eccentric screw pump whose stator has end-side end faces with wall thickness varying over the circumference. To ensure that there is no excessive axial compression of the stator material, circumferential grooves are provided, each spaced from the axial end of the stator. In addition, holding elements are provided, which are each formed in a semi-annular shape and which engage in the grooves.

Finally, in the DE 10 2004 038 477 B3 an eccentric screw pump with a tubular rigid stator shell and with a substantially uniform over almost the entire length of the stator elastic lining described.

The invention has for its object to provide an eccentric screw pump of the type described above, which is characterized by optimized operation (even at high operating pressures) and in particular by a reduced wear of the stator.

To solve this problem, the invention teaches an eccentric screw pump with the features of claim 1.

The stator is basically fixed between the pump housing and the connection housing in the axial direction, and preferably between the connection flanges of the pump housing on the one hand and the connection housing on the other. Nevertheless, in practice there is the problem that the elastomeric stator can partially deflect in the axial direction at the ends, so that the aforementioned displacements or expansions relate in particular to partial and consequently locally limited displacements or expansions, relative to the cross-section of the stator. Because if the stator at its ends in certain localized areas evades in the axial direction, it can lead to deformation of the stator and thus to the deviation of the geometry of the stator of the desired geometry. Such an axial displacement leads to a geometry offset between rotor and stator and this can locally (eg on one side with respect to the cross section) to a lifting of the clamping (eg on one side) and to a Überklemmung in another area (eg on the other side). This can lead to increased wear in areas in the over-clamped regions.

The Ausrücksicherung invention prevents such axial deflection of the elastomeric material and thus deviations in the geometry of the stator of the desired geometry are easily and reliably avoided. The described problems of Unterklemmung or Überklemmung be avoided, so that pressure losses are reduced and increased wear is avoided. Furthermore, the avoidance of under or over clamping also causes a reduced torque and thus an increased energy efficiency of the pump.

Particularly preferably, the disengagement device according to the invention is used in an eccentric screw pump with a longitudinally split stator jacket, which has a plurality of clamping segments and thus forms a stator clamping device. Furthermore, it is preferably provided that the stator is designed as a longitudinally divided stator. In that regard, the principle known embodiments WO 2009/024 279 A1 or DE 10 2014 112 550 B4 be resorted to, but supplemented by the Ausrücksicherung invention. In principle, however, the invention can also be used in other embodiments, for. B. are used in Einschubstatoren, in which both the stator jacket and the elastomeric stator are each formed in one piece and in which the stator is inserted into the tubular stator shell and consequently also formed detachably and separately from the stator jacket. Finally, in principle, embodiments are also encompassed in which the stator is vulcanized into the stator casing or otherwise fixed in the stator casing, the described axial displacements which are to be prevented with the release fuse occurring to a lesser extent in such embodiments.

The release lock is arranged in the region of the parts of the pump housing or the connection housing, against which the stator rests in the mounted state. This may preferably be the respective connection flanges of the pump housing and / or the connection housing. As a rule, the stator is clamped in the axial direction between the connection flange of the pump housing (eg suction housing) and the connection flange of the connection housing (eg pressure port). Such disengagement can be provided on the pressure side, z. B. in the area of the pressure nozzle. However, it is also within the scope of the invention, the Ausrücksicherung suction side, z. B. in the area of the pump housing. Furthermore, both on the pressure side and on the suction side each a release lock can be provided. The design can also be adapted to the respective structural and geometric conditions of the pump. So it may be z. B. be expedient to provide the disengagement especially at the end remote from the coupling rod end of the rotor or stator and at the end of the coupling rod facing the rotor / stator to dispense with a disengagement to facilitate assembly / disassembly. The connection flanges on which the release lock (s) is / are provided can be an integral part of the connection housing (pressure port) or the pump housing (suction housing). However, the connection flanges may also be separate adapter pieces which are mounted on the pump housing or the connection housing.

The release lock is integrated in the connection flange or in the respective housing, with the formation of a different from the circular inlet cross-section of the connection flange (in the respective housing). As a rule, the connection flanges in the prior art have a circular inner cross-section. According to the invention the disengagement ensures that this inner diameter is reduced and receives a deviating from the circular shape. This can be z. B. realize that the disengagement is formed by one or more fuse panels, which are integrated like a diaphragm in the connection flange. However, such fuse covers extend (in each case) only over a limited circumferential area, relative to the connection flange or relative to the stator. So z. B. be integrated into the connecting flange, two fuse covers which form the edges facing the center as it were secants of the circular inner cross section of the connecting flange (without the panels).

It is important that the stator in a preferred embodiment and in basically known manner over the length (substantially) constant, circular outer cross-section and a helical Statorinnenraum having deviating from the circular inner cross-section. Different stator geometries are known. For example, the inner cross section may be formed slot-shaped. In any case, such a stator has a wall thickness varying over the circumference. It is provided that the end-side end faces of the stator have a wall thickness varying over the circumference. The stator is now connected to the connection flange (with release lock) in such a way that end face areas of the stator with greater or maximum wall thickness bear against the release lock while end face areas with a smaller or minimal wall thickness do not bear against the release lock. The invention is based on the recognition that the elastomeric material can escape to a particular extent in the areas in the axial direction, in which there is a particularly large wall thickness. In these areas now prevents the Ausrücksicherung such Dodge, because the disengagement is preferably arranged in such areas in which the stator has a large wall thickness. The disengagement safety device (eg diaphragm) is particularly preferably dimensioned such that it has a cross section on the abutment surface that lies within the cross section of the abutment surface of the regions with a large wall thickness. Consequently, the elastomeric material of the stator in the end face regions is preferably not completely covered by the release lock. In this way, any problems with interference edges against the rotor can be avoided. If z. B. a stator is provided with slot-shaped interior, both sides of the straight sections of this long hole, the end face areas are provided with a large wall thickness and in these areas are then z. B. two fuse covers are provided which prevent disengagement without the media flow is impaired.

In principle, there is the possibility that the securing apertures are simple sheets or the like. However, particularly preferred are Ausrücksicherungen, z. As fuse covers, used, which are ramped in cross-section, z. B. are wedge-shaped, in such a way that the deviating from the circular inlet cross-section merges into a circular channel cross-section of the connection housing or the pump housing. This means that the reduced by the Ausrücksicherung inlet cross section of the connecting flange or the respective housing, behind the Ausrücksicherung not abruptly changes or extended, but over the ramped cross section of Ausrücksicherung is a continuous transition of the reduced inlet cross section in the usual circular interior of the respective Flange or housing made. This avoids negative influences of the release locks on the flow within the pump. Overall, a flow-optimized housing part is provided in which deposits are reduced. Improved inflows of solids into the pump geometry and lower risk of clogging are also achieved. Preferably, the NPSH values are also improved. The described ramp-shaped cross-section can, for. B. wedge-shaped (with a straight or flat sloping surface) may be formed. In the context of the invention, however, ramp-shaped embodiments also include embodiments with ramps which have a concave or convex longitudinal section.

Basically, it is possible to use the disengagement as a separate component, eg. B. to design separate disc, which is arranged between the respective housing and the stator end. Particularly preferably, however, the invention proposes that the disengagement safety device be formed integrally therewith as an integral part of the connection housing or of the pump housing or of the respective connection flange. If the respective housing z. B. is produced as a cast housing, the invention proposes that the disengagement is an integral part of this casting and consequently manufactured by way of casting. In other types of manufacturing the housing, the disengagement can also be formed by machining or the like from the respective housing part. In an alternative embodiment, the invention also includes embodiments in which the Ausrücksicherung is first prepared as a separate component and then firmly connected to the respective housing part or the flange, z. B. by way of a welded joint.

It has already been mentioned that the stator is preferably clamped between the pump housing and the connection housing or between the respective flanges of these housings in the axial direction. For this purpose, the stator has end-side sealing surfaces, the z. B. as a conical sealing surfaces, preferably as innenkonische sealing surfaces may be formed. The housing or its connection flanges accordingly have corresponding sealing counter surfaces, for. B. conical sealing mating surfaces, preferably outer conical sealing mating surfaces. It can on the findings of z. B. the WO 2009/024 279 A1 or the DE 10 2014 112 550 B4 be resorted to. In the case of outer conical sealing counter surfaces and inner conical sealing surfaces of the stator, the stator or the stator shells is placed on the outside as it were on the sealing counter surfaces of the connecting flanges. In a preferred development, it is now proposed that the disengagement safety device (eg the safety shutters), at the end facing the stator, terminate flush with the sealing mating surface of the respective housing or flange. This means that the release lock extends in the axial direction up to the sealing counter surfaces and pass into this.

• 1 eine Exzenterschneckenpumpe in einem vereinfachten Vertikalschnitt in Längsrichtung,
• 2 ein Anschlussgehäuse (Druckstutzen) für eine Exzenterschneckenpumpe in einer perspektivischen Darstellung,
• 3 einen Längsschnitt durch den Gegenstand nach 2.

In the following the invention will be explained in more detail with reference to a drawing showing only one exemplary embodiment. Show it:

• 1 an eccentric screw pump in a simplified vertical section in the longitudinal direction,
• 2 a connection housing (discharge nozzle) for an eccentric screw pump in a perspective view,
• 3 a longitudinal section through the object 2 ,

In the figures, an eccentric screw pump is shown, which in its basic Build a stator 1 made of an elastic material and one in the stator 1 rotatable rotor 2 wherein the stator at least partially by a stator jacket 3 is surrounded. The pump has a pump housing 4 on, which is formed in the embodiment as a suction housing, and a connection housing 5 , which is also referred to as a discharge nozzle. Furthermore, the pump has a drive 6 on, which via a connecting shaft or drive shaft 7 and a coupling rod 8th to the rotor 2 connected. The coupling rod is over joints 9 on the one hand to the rotor 2 and on the other hand to the connecting shaft 7 connected, these joints are designed so that they allow the eccentric movement of the rotor.

The suction housing 4 has a connection flange 10 on and the connection housing 5 has a connection flange 11 on, with the stator 1 between these connection flanges 10 . 11 arranged and fixed in the axial direction. These connection flanges 10 . 11 can be integral part of the respective housing 4 . 5 be or be formed by separate adapters. 1 shows such an embodiment in which the connecting flanges 10 , 11 are formed by adapter pieces. In contrast, shows 2 an embodiment in which the connecting flange 11 of the connection housing / pressure connection 5 integral part of this case 5 is.

The stator 1 is designed as a longitudinally divided stator and to do this he consists in the embodiment of two merely indicated stator half shells 1a . 1b , Longitudinal means, along the stator longitudinal axis or parallel to this.

The stator jacket 3 is also formed as a longitudinally divided sheath and it has a plurality of sheath segments 12 which serve as clamping segments and form a Statorspannvorrichtung. For this purpose, the stator jacket 3 a mounting flange 13 on, ie each clamping segment 12 has a portion of this mounting flange 13 on and with this mounting flange 13 can the stator jacket 3 in the radial direction against the stator 1 tense. Details are not shown, they are z. B. from the DE 10 2014 112 550 B4 or the WO 2009/024 279 A1 known.

The stator 1 has end sealing surfaces 14 on, the conical or conical surfaces 14 are formed, in the embodiment "inside-conical". The connection flanges 10 . 11 have as Statoraufnahmen also corresponding conical sealing counter surfaces 15 on, which may be externally-conical. The seal is made by rubber squeezing. The already described sealing of the stator partial shells 1a, 1b takes place with the aid of the radially braceable stator jacket 3 or its segments 12 ,

According to the invention, at least in the region of the stator end, which is the connection housing 5 is assigned, an elastic stator 1 against displacement or expansion in the axial direction limiting Ausrücksicherung 16 intended. This is in 1 not shown, but in 2 recognizable, in the area of the connection housing 5 , In principle, there is the possibility of such a disengagement 16 also in the area of the pump housing 4 provided. This is not shown in the figures. This release lock 16 prevents local deflection of the elastomeric stator material in the axial direction, locally relative to the stator cross-section.

Because in the exemplary embodiment, the stator 1 a substantially constant over the length circular outer cross-section and a helical stator interior 18 with deviating from the circular shape inside cross section. In the exemplary embodiment, this inner cross section, in which the rotor moves, is formed oblong-shaped. This means that the wall thickness of the stator varies over the stator circumference and is therefore not constant. It follows that the end faces 19 of the stator have a varying wall thickness over the circumference. This is in 2 merely hinted. The stator is in this way to the connection flange 11 connected to the face areas 19a of the stator with a large wall thickness against the release lock 16 abut, allowing a deflection of the elastomer in these areas 19a the large wall thickness is prevented. This ensures that deformations and thus deviations of the actual geometry from the desired geometry are simply and reliably avoided, so that the function of the pump is optimized.

Here is the disengagement 16 integrated in the exemplary embodiment to form a deviating from the circular inlet cross section in the connection flange. It is in the embodiment of two safety shields 16a formed, which blind in the connection flange 11 are integrated and each only over a limited peripheral area - with respect to the flange or stator - extend. It is in 2 recognizable that the design, geometry and arrangement of the fuse covers 16a to the geometry of the end-side end face 19 of the stator 1 is adapted to the expansion / displacement of the elastomeric material, especially in the areas 19a to avoid high wall thickness.

In the illustrated embodiment, the Ausrücksicherung 16 or are the fuse covers 16a integral part and therefore integral with the connection flange 11 educated. Because the connection flange 11 in the embodiment according to 2 integral with the connection housing 5 is formed, is the disengagement 16 also formed integrally with the connection housing 5. The component 5 can be made as a one-piece cast component, so that the release 16 is produced in the course of casting.

Furthermore, in 3 recognizable that the release lock 16 or the fuse covers 16a ramped in cross-section with a sloping ramp to the interior 17 are formed. This has the consequence that the deviating from the circular shape inlet cross section continuously into the circular channel cross-section of the connection housing 5 passes.

Incidentally, in 3 recognizable that the release lock 16 or the fuse covers 16a flush with the sealing surfaces 15 close or directly into the sealing counter surfaces 15 pass.

The in the 2 and 3 exemplary for the connection housing 5 illustrated embodiment can be in a corresponding manner in or on the suction housing 4 realize.

Claims (8)

Eccentric screw pump having at least - a stator (1) of elastic material, - a rotor (2) rotating in the stator, - a stator casing (3) surrounding the stator, - a pump casing (4) connected to the stator (1) at a first end ), - a terminal housing (5) connected to the stator (1) at a second end, wherein the stator (1) has end-side end faces (19) with wall thickness varying over the circumference, characterized in that in the region of at least one end of the stator elastic stator (1) is provided against expansion or displacement in the axial direction limiting Ausrücksicherung (16) that the Ausrücksicherung (16) to form a deviating from the circular inlet cross-section in the connecting flange (10, 11) or in the respective housing (4, 5) is integrated and that the stator (1) is connected to the connecting flange (10, 11), that end face regions (19 a) with maximum wall thickness against d The release lock (16) rest. Eccentric screw pump after Claim 1 , characterized in that the Ausrücksicherung (16) in or on a stator receiving the connecting flange (10, 11) of the connection housing (5) and / or the pump housing (4) is fixed. Eccentric screw pump after Claim 1 or 2 , characterized in that the Ausrücksicherung (16) of one or more securing apertures (16a) is formed, which are blind-like in the connecting flange (10, 11) or in the respective housing (4, 5) are integrated and only over a limited peripheral region extend. Eccentric screw pumps according to one of Claims 1 to 3 , characterized in that the disengagement (16), z. B. the fuse panels (16 a), is dimensioned / are such that they are completely absorbed by their contact surfaces in the mounted state of the respective end face region of the stator, z. B. completely within the cross section of the contact surface of the end face areas with maximum wall thickness. Progressing Cavity Pump according to one of the Claims 1 to 4 , characterized in that the disengagement (16), z. B. the securing apertures (16 a), is formed in such a ramp in cross-section is / are that of the deviating from the circular inlet cross section in a circular channel cross section of the connection housing (5) or the pump housing (4) passes. Progressing Cavity Pump according to one of the Claims 1 to 5 , wherein the stator (1) end sealing surfaces (14), z. B. internal conical sealing surfaces (14) which against corresponding sealing mating surfaces (15), z. B. outer conical sealing mating surfaces (15) of the connection flanges (10, 11) of the connection housing (5) or the pump housing (4) abut, characterized in that the Ausrücksicherung (16), z. B. the securing apertures (16 a), on which the stator (1) facing the end flush with the sealing mating surface (15) or complete. Progressing Cavity Pump according to one of the Claims 1 to 6 , characterized in that the Ausrücksicherung (16) as an integral part of the connection housing (5) or the pump housing (4) or the respective connection flange (10, 11) is integrally formed therewith, for. B. in the embodiment as a casting. Progressing Cavity Pump according to one of the Claims 1 to 7 , wherein the stator jacket (3) is formed as a longitudinally divided shell of at least two clamping segments forming shell segments (12) and / or wherein the elastic stator (1) as a longitudinally divided stator of at least two Statorteilschalen (1a, 1b), z. B. half shells is formed.

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