WO2016150414A1

WO2016150414A1 - Sealing-line-optimized progressive cavity pump

Info

Publication number: WO2016150414A1
Application number: PCT/DE2016/000047
Authority: WO
Inventors: Christian BINDIG; Josef Strohhofer
Original assignee: Netzsch Pumpen & Systeme Gmbh
Priority date: 2015-03-26
Filing date: 2016-02-10
Publication date: 2016-09-29
Also published as: DE112016001402A5; DE102015104549A1

Abstract

The invention relates to a progressive cavity pump having an inner and an outer pump part (10, 4) as a rotor-stator assembly (2), having sealing lines (14a, b) formed between the rotor (10) and the stator (4), wherein the friction forces occurring between the rotor (10) and the stator (4) should be reduced without jeopardizing the operational reliability of the pump. For this purpose, according to the invention, the pump has an outer pump part (4), wherein the outer pump part (4) is at least partially friction-optimized in a sealing-line width region (16) and/or at least one pump part (10, 4) is at least partially friction-optimized in an end region (30) of the rotor-stator assembly (2), and/or at least one pump part (10, 4) is at least partially contact-preventive in the end region (30), wherein the end region (30) is defined as a region having partially unneeded sealing lines.

Description

description

Sealing line optimized eccentric screw puff

The invention relates to an eccentric screw pump having an inner and an outer pump part as a rotor-stator assembly, which at contact points between the rotor and stator continuously extending sealing lines form, an inner and an outer pump part for such an eccentric screw pump and a core body for producing the outer pump part. The

The invention further relates to a method for switching off an eccentric screw pump.

Eccentric screw pumps are rotary positive displacement pumps with a Roto _^ r-stator assembly comprising an inner and an outer pump portion, wherein the inner part is usually designed as rotor and the outer part as a stator. However, eccentric screw pumps with a rotor-stator arrangement in which the outer pump part serves as a rotor or both parts are counter-rotating rotors are also known.

In a rotor-stator arrangement with an inner pump part as a rotor and an outer pump part as a stator, the rotor is helically formed with a large pitch and flight depth and a relatively small core diameter. It is arranged eccentrically in the stator. The stator has one turn more than the rotor. Between the rotor and the stator arise so

Conveyor rooms that move continuously from the inlet to the outlet side.

Progressive cavity pumps are known in which the stator consists of an elastomeric body and a stator jacket, wherein the stator jacket surrounds the elastomer body. The elastomeric body causes a seal between the rotor and the stator, which can be generated by the fact that the inner contours of the

Stators are smaller than the outer contours of the rotor. The resulting bias creates uninterrupted

Sealing lines, which seal the successive delivery chambers and allow the construction of a delivery pressure.

The sealing lines separate and seal the delivery chambers and consequently the suction side of the stator from the pressure side. They extend both as longitudinal sealing lines as well as transverse sealing lines in the interior of the rotor-stator assembly. The formation and sealing of a delivery chamber is carried out by two longitudinal and two transverse sealing lines, which meet or overlap in a width range between two delivery chambers.

In a static view, the sealing lines thus form the shape of a linked in the width range double helix, which forms depending on the rotor-stator position between the rotor and the stator. Dynamically considered, that is at

Operation of the pump, the transverse sealing lines migrate from the suction side to the pressure side, while the axially extending sealing lines in the periphery of the rotor-stator assembly a

Describe rotational movement.

Rotor and stator have different slopes and differ in a defined ratio of the number of gears. A pumping system with a catchy rotor and a

double-flighted stator is referred to as a 1/2-speed pumping system. The length of the delivery chamber and thus also the length of the axially extending sealing lines between two adjacent

Width ranges correspond to a stator pitch. The

Pressure capacity of the eccentric screw pump results inter alia then from the number of delivery chambers, which are also referred to as stages. Due to the required sealing lines, frictional losses occur during operation of the pump, and a starting torque, which is influenced by the friction between the rotor and the stator, during startup of the pump adversely affects its operational safety and efficiency. From the prior art solutions are known, for example, the Anfahrkräfte a

To reduce the progressing cavity pump.

For example, from the published patent application DE 36 41 855 AI an eccentric screw pump with an adjustable stator disclosed in a circumferentially by longitudinal slots in

Vulcanized segments segmented pipe casing and is provided with at least one comprehensive the pipe jacket clamp.

By an adjustable clamp, which is arranged radially mitbeweglich with the individual segments of the tube shell, excessive frictional forces between the rotor and stator are to be avoided. The adjustable stator can be initially stretched radially at start of operation, so that the operation of the pump can be approached with normal conditions. About adjusting screws of the clamp, the stator can be adjusted or adjusted in terms of friction.

However, an eccentric screw pump would be desirable

To provide that counteracts a loss of friction permanently and without additional operating effort. The known from the prior art (SdT) solutions of the type mentioned above are but insufficiently suitable. In addition, at

conventional progressing cavity pumps through which

Stator setting, the friction forces are reduced only to a point where at least just enough pressure between the rotor and the stator is present to prevent the sealing lines from being interrupted or removed. Finding out this critical point has proven to be very expensive in practice. In this known solution is also to be considered that shifts the point of optimal sealing, with the least possible friction, when starting the pump and operation.

The invention is therefore based on the object, a

To specify an eccentric screw pump of the type mentioned, are reduced in the friction forces occurring between the rotor and stator, without jeopardizing the reliability of the pump.

The object is achieved by an outer pump part in a sealing line width range and / or

at least one pump part in an end region of the rotor-stator arrangement, at least partially friction-optimized and / or at least one pump part in the end region is at least partially formed contact-preventing, wherein the end-side region is defined as an area with partially not required sealing lines.

To produce an outer pump part according to the invention, a core body is proposed, which corresponds in shape to the inner shape of the desired outer pump part and which is provided with a friction-optimizing recesses (18) forming structure (24) in a sealing line width range.

Preferably, the outer pump part is a stator and the inner pump part is a rotor.

The invention is based on the consideration that only

Areas and sections of the sealing lines should be stressed, which also ensure safe operation of the pump required are. In particular, sealing line areas should be non-functional without contact between the stator and the rotor so as not to generate unnecessary friction. In addition, these areas could be used for other purposes, such as inlet or outlet for the fluid. The pump could be made more compact than conventional progressing cavity pumps.

For example, however, the inlet or outlet area could be increased to the flow resistance in these

Reduce areas and wear out

counteract occurring cavitation. In pumps with a gap between the stator and the rotor, also called gap pumps, are used in practice essentially for the promotion of highly viscous media. Despite the contactless rotor-stator arrangement, friction and shear forces occur in a sealing line area between the rotor and the stator, which could be reduced by the solution according to the invention.

Between rotor and stator extending in the longitudinal direction of the rotor-stator assembly sealing lines. These longitudinal

Sealing lines are usually limited in known stators by the stator and are connected by transverse sealing lines in a wide range. In order to reduce the frictional forces, the surfaces between stator and rotor in this area are preferably

friction optimized trained. For this purpose, with regard to one or more specific rotor-stator positions, in a single or multiple design, the opposing surfaces in the region of the sealing lines are friction-optimized. It should be noted that a required sealing of the chambers is always achieved. Thus, an adaptation of rotor and / or stator is not over their entire surface

required, which, for example, manufacturing and

Maintenance costs keeps low. By preferably preventing contact between the rotor and the stator at the end, no contact friction occurs at these locations. This is possible because in this area of the rotor-stator arrangement, not all longitudinal

extending sealing lines have a sealing function and are not required for medium promotion. The end region, in which at least partially by a corresponding

Embodiment of the rotor and / or stator contact is prevented, is limited in the longitudinal direction of the rotor-stator assembly, such that required for medium promotion sealing lines or sealing line components are retained, but in other areas, the contact between the rotor and stator is prevented. Instead of a kontaktverhindernden embodiment of the rotor-stator assembly, the rotor-stator assembly in the end

Area also partially optimized friction.

With such a rotor-stator arrangement, which is formed in an end-side area at least partially contact preventing or optimized friction, a startup of the eccentric screw is advantageously improved by the eccentric screw pump with a controllable or adjustable

Drive device is equipped and the rotor after

Switching off the eccentric screw pump is brought into a position in which there is at least partially no or a friction-optimized contact between the rotor and stator in the end region. The occurring when starting the pump high

Starting torque, can be effectively reduced.

Preferably, the drive device comprises a synchronous motor as a drive motor.

The end region with the partially imperceptible sealing line portions can be determined by the surface of the stator, which faces the rotor and the surface of the Rotor, which faces the stator, fictitious in any number, but preferably in a large number of subareas Ai to A _{n is} divided. During one revolution of the rotor, each partial area A _x is considered separately. Should A _x during this revolution be one or more times part of a sealing contact between rotor and stator, the a) two closed delivery chambers or

b) a closed delivery chamber and the pressure side of

Eccentric screw pump or

c) a closed delivery chamber and the suction side of

Eccentric screw pump or

d) the pressure side and suction side separates, the area A _x in the category

"Required" divided. The sub-areas, not the

Category "required" to be assigned, the receive

Classification "not required." This test is repeated for all subareas Ai to A _n .

The extent with subareas of the category "not

required ", based on the rotor or the stator, defines the end region according to the invention, which the

Contains surfaces with the non-required sealing lines. Within the partial surface region, the rotor and / or the stator may be provided with contact-preventing recesses, have a friction-optimized surface or be withdrawn to reduce the bias, without the pumping effect being significantly impaired.

In the embodiment of the invention, with the

kontaktverhindernden end portions of the rotor-stator assembly, in an advantageous manner, depending on a radial distance between the opposing rotor and Stator surface, an inlet and outlet for the medium to be increased. For this purpose, are the

Recesses to the suction and / or pressure side open, so that pumped medium can also flow through the recesses in the suction or pressure housing of the eccentric screw pump. An effect on the pumping effect disadvantageous cavitation, by excessive flow velocities, can be so effective

be counteracted.

Basically, recesses within the

Partial area be introduced in the end region in any number, design and dimensions. Preferably, the pump parts are in the longitudinal direction over a length

formed contact preventing, which corresponds to the extension of the end region in this direction. The inlet and outlet area can thus be extended maximally in the longitudinal direction of the rotor-stator arrangement. Particularly preferred is a recess introduced in the inner and / or outer pump part, which substantially corresponds to the area of the sum of the partial areas A _x to A _{n of} the category "not required", that is to say relating to the entire partial area.

It is considered advantageous if at least one pump part has a friction-optimized surface. The surface may be tuned to the surface of the opposite pump part, in order to reduce the friction to a minimum.

In a preferred embodiment, the friction-optimized surface is formed by contact-reducing recesses in the stator. The arrangement of the recess and also a resulting structure can be arbitrary, as long as the sealing line, outside the end-side area, is not interrupted. For this purpose, the recesses are preferably not in communication with each other, such that a seal between the Delivery chambers and between the pressure and the suction side of the rotor-stator assembly is guaranteed.

Particularly preferably, the recesses are arranged substantially transversely to the longitudinal axis of the rotor-stator arrangement and are within the width range of the sealing lines, which due to the contact between the rotor and stator, has a certain width. Within the end-side region according to the invention outside the required sealing lines, the recesses may communicate with each other, so that at this point there is basically no restriction as to the type or structure of the recess.

The expansion and design of the friction-optimized area can be selected based on a surface or volume analysis of the overlap or the gap between the stator and rotor so that depending on geometry, tolerance field of rotor and stator and material parameters as uniform as possible

Sealing effect is to be expected at all points of the longitudinal and transverse sealing lines of the rotor-stator system. An evaluation of a particular friction-optimized designed rotor-stator combination can be carried out via experiments.

The characteristic features for expansion and design of the friction optimized area are the beginning and the end of the

Recesses, when the friction-optimized area is achieved by a reduced bias, the amount by which the bias voltage is reduced depending on the location and when the friction-optimized area forms a structure, the width of the recesses, their distances from one another, their depth and shape.

Preferably, at least one pump part in the end region has at least partially contact-preventing recesses. Thus, rotor and / or stator in the entire area or even in a subarea of this arbitrarily with

friction-optimizing recesses are provided without

Considering the tightness of the rotor-stator assembly to take.

According to a preferred embodiment, the stator is formed friction-optimized by a partial reduction of a bias voltage. This ensures that only to the

Friction of the stator surface according to the invention is reduced by reducing the pressure from the stator to the rotor by the selectively reduced bias voltage. The

Bias can be so beneficial for example in the

Adjusting the sealing line width range.

The width of the sealing lines is determined by a

Contact surface between the rotor and the stator. In gap pumps whose width corresponds to an area where essentially

due to the small gap still a sealing effect occurs. This area is mainly in a wide range, the area by the longitudinal sealing lines on the transverse

running sealing lines, comparatively large. The stator is friction-optimized in this area, in particular provided with friction-optimizing recesses. The fact that the recesses are introduced at these locations of the stator, the friction is advantageously reduced to the place where it occurs reinforced. However, the recesses may also be filled with a friction-optimizing material, thereby maintaining or improving, for example, the mechanical properties of the stator in the width range.

In a particularly advantageous embodiment, the recesses are introduced in all width ranges and over the entire stator length. The friction can thus for the entire stator be effectively reduced without the sealing lines are interrupted in their function.

The rotor of the eccentric screw pump is preferably provided with a contact-preventing recess which continuously reduces in longitudinal direction toward the center of the rotor-stator arrangement. This results in a

flow-optimized design. It will continue as

considered advantageous if the recesses have no sharp edges, in particular when the edges of the recesses are rounded.

The outer pump part is preferably provided with at least one contact-preventing recess, which likewise decreases continuously in the longitudinal direction towards the center of the rotor-stator arrangement. Analogous to the recess in the rotor, the reaction to achieve an inventive

Contact prevention between stator and rotor, also possible because the contact-preventing recess is introduced in the stator. Again, the recesses should have no sharp edges. The edge radius and the

Edge geometry should preferably be chosen so that thereby a flow-optimized pump inlet and outlet for a pumped medium can be provided. In a frontal flow-optimized geometry of the stator, for example in the form of a funnel-like inlet and outlet, a soft transition towards the recesses causes a

Improvement of the flow of the pumped medium.

However, instead of the contact-preventing recess, in order to achieve improved stability and guidance in the described stator region, the stator can also be provided with a stator

friction-optimizing material such as Teflon be provided. In order to achieve an advantageous friction-optimizing effect, it is basically only necessary for at least one pump part to be friction-optimized and / or regionally

is designed to prevent contact. Preferably, however, both pump parts friction-optimized and / or partially formed contact preventing.

The inner pump part, as part of the rotor-stator arrangement for an eccentric screw pump, can therefore according to the invention in an end region at least partially

Optimized friction and / or at least partially

be designed to prevent contact, the end-side

Range is defined as an area with partially impermeable sealing lines.

In an eccentric screw pump in which the inner pump part is the rotor, the rotor, by a in the sense of

Invention improved rotor can be replaced without even replace the stator. Instead of the recess can in the

described rotor end region of the rotor may also be provided with a friction-optimizing layer such as Teflon.

Conversely, however, an outer pump part, as part of a rotor-stator arrangement for an eccentric screw pump,

in an end region at least partially

Optimized friction and / or at least partially

be designed to prevent contact, the end-side

Range is defined as an area with partially impermeable sealing lines.

For this purpose, it is preferably provided that the outer pump part an inlet and / or outlet for a pumped medium which extends radially outwardly and which is defined as an area with non-required sealing lines, wherein the end-side area according to the invention in

Longitudinal is limited, for example, at 1/4 of the slope of the outer in a 1/2 common rotor-stator arrangement

Pump part. Inlet and outlet of an eccentric screw pump with such a pump part can be arranged in an advantageous manner laterally on the outer pump part.

Particularly preferably, the outer pump part has an as

Cutout formed recess, which corresponds to the sum of the partial areas Αχ to A _{n of} the category "not required", ie the entire partial area.

To produce an outer pump part according to the invention, a core body is preferably provided, which corresponds in shape to the desired inner shape of the outer pump part and in the sealing line region with a

friction-optimizing recesses forming structure is provided. The core body is for example in one

cylindrical hollow body arranged and surrounded with an elastomer composition. After crosslinking, the core body is removed again and the elastomeric stator can be removed from the cylindrical hollow body.

The surface of the core body corresponds to one

Negative shape of the surface inside the stator. The structure is designed such that in the longitudinal direction of the stator

closed sealing lines can be formed.

The advantages achieved by the invention are, in particular, an energy-efficient and low-wear

To provide progressing eccentric pump by the rotor-stator assembly is configured friction optimized. This can also improve the starting behavior of the pump, whereby, for example, a cost-optimized drive dimensioning can take place. The fact that the stator is provided with inlet and Auslasserweiternden and kontaktverhindernden recesses, also the pump can be compact and with

comparatively low cost. By means of the core body, a simple production of the stator according to the invention is made possible. In addition to the friction-optimizing structure, the core body can be partially radially expanded at the end, whereby the contact-preventing recesses can then be formed in the stator.

Embodiments of the present invention are disclosed in

described in an exemplary manner with reference to the attached drawings. Show:

Fig. 1 shows schematically the rotor-stator assembly of the

Prior art known eccentric screw pump,

2 shows schematically the sealing line course, comprising longitudinal and transverse sealing lines,

Fig. 3 shows schematically a sealing line section, comprising a

Width range of a by means of recesses

friction-optimized stator,

Fig. 4 shows a schematic perspective view of a

Stator with a friction - optimizing structure in the continuous line of the seal line width

Longitudinal section

Fig. 5 schematically shows a friction-optimized stator in FIG

Cross-section, which is provided with the friction-optimizing structure associated recesses, 6 shows a perspective view of a core body for producing a stator according to the invention, which is provided with a structure forming the friction-optimizing recesses,

Fig. 7 shows schematically a known from the prior art

Stator, with an elastomeric body comprised of a stator jacket,

8 is a schematic perspective view of a rotor-stator arrangement, wherein the stator end-contact-preventing recesses,

9 is a schematic cross-sectional view of the stator of FIG. 8; FIG.

10 is a schematic side view of the stator of FIG. 8, FIG.

11 is a schematic perspective view of a rotor-stator arrangement with a rotor, which has contact-inhibited recesses at the end,

12 is a schematic perspective view of the rotor of the rotor-stator arrangement of FIG. 11,

13 is a schematic side view of the rotor of FIG. 12,

FIG. 14 schematically shows cross sections of the rotor from FIG. 12 in FIG

Seen in the longitudinal direction,

15 is a schematic perspective view of a rotor-stator arrangement with a rotor and a stator, which have contact-inhibited recesses at the end. Identical parts are provided with the same reference numerals in all figures.

1 shows a known from the prior art rotor-stator assembly 2 of an eccentric screw pump, comprising a stator 4 as an outer pump part, with a stator shell 6 and an elastomer body 8 for receiving a rotor 10 as an inner pump part. Between the rotor 10 and the elastomer body 8 chambers 12 are formed for receiving the pumped medium. The

Sealing of the chambers 12 is achieved by a bias in that the elastomeric body 8 has an internal dimension that is smaller than an outer dimension of the rotor 10.

The rotating within the elastomer body 8 rotor 10 generates in a conventional manner from the suction side to the pressure side, the helically traveling chambers 12, wherein the fluid enters through an opening in a pump housing (not shown). It thus passes between the rotor 10 and the elastomer body 8 to a discharge nozzle (not shown), where it exits. The rotor 10 moves eccentrically about the longitudinal axis of the stator 4 at a distance E.

A section of the sealing lines 14a, b one

Eccentric screw pump in static view, with a 1/2 common geometry pairing, is shown in Fig. 2. In this approach, the sealing lines thus form the shape of a linked in the width range double helix, which forms depending on the rotor-stator position between the rotor and the stator. The sealing line can be divided into 3 sections

be split. On the one hand in the end-side sections D and S, on the other hand in the section K, which defines the chamber for the pumped medium. The section D is located on the pressure side with respect to the chamber and the suction side S on the suction side. The sealing lines 14a, are composed of two transverse sealing lines 14a and two extending in the longitudinal direction

Sealing lines 14b together. The section K is in

Limited longitudinal direction by the transverse sealing lines 14b. The meeting at this point

Sealing lines 14a, b form a width region 16. In this region, line-shaped recesses 18 may be introduced (not shown). The recesses 18 would, as also shown in Fig. 3, form a friction-optimizing structure 20, which should be aligned and arranged so that the sealing lines 14a, b are not interrupted to ensure the sealing of the delivery chamber.

Such a width region 16, formed by line-shaped recesses 18, is enlarged by way of example in FIG. 3

shown. The recesses are to be so in the

associated stator arranged and arranged that neither the transverse sealing line 14 a nor the longitudinal sealing lines 14 b are interrupted in terms of their sealing effect, which is a prerequisite that the

Delivery chambers are sealed and over the entire stator length an uninterrupted sealing line 14a, b is maintained. The depth of the recess 18 is chosen so that even under the pressure of the rotor 10 on the stator 4, a reduced contact surface remains and thus can also have a friction-reducing effect.

4 shows the elastomer body 8 of a multi-stage

Stators 4, on the surface of the inside of such friction-optimized acting structures 20 are introduced. These run within the width ranges 16 helically over the entire length of the stator. Since the friction-optimized structure 20 as many as possible

Points in the elastomeric body 8 should be introduced, where, by contact between the rotor 10 and stator or elastomeric body 8, a seal for the delivery chambers is required, resulting in such a rotor-stator assembly a total of four of these helically extending

Structural surfaces 20 which extend within the width regions 16 of the sealing lines.

As illustrated in FIG. 5, the structure-forming

Recesses 18 at reversal points in the elastomer body. 8

introduced where the width ranges 16 are located. The recesses 18 are for better illustration

shown enlarged and do not correspond to their actual dimensions and size ratio to the elastomeric body. 8

A core body 22 for producing a novel

Stators Fig. 6. This corresponds in shape to the inner shape of the stator and is provided in the sealing line area with a friction-optimizing recesses forming structure 24. The total of 4 around the core body 22 helically extending around the structure surfaces 26, cause an im

Sealing line width range friction-optimized surface of the stator.

As shown in Fig. 7, a stator 4 is known from the prior art, which has a stator shell 6, which corresponds in shape to the inner shape of the elastomer body 8. This embodiment has the advantage that comparatively little elastomer is required for stator production, which, inter alia, leads to an advantageous cost and weight reduction. The following embodiments according to the invention in FIGS. 8 to 15 are exemplary with reference to a 1/2 conventional rotor-stator arrangement.

An elastomeric body 8 for such a stator is shown in FIG. 8. In the elastomeric body 8, a rotor 10 is arranged, which has a circular cross-section. The rotor-stator assembly 2 is provided for a 1-stage eccentric screw pump. The elastomer body 8 has end-contact-preventing recesses 28 which also extend the inlet and outlet of the rotor-stator assembly 2. By thus inlet and outlet of the pump can be arranged laterally on the stator, a compact design is possible. However, such a rotor-stator arrangement 2 can also be used in a conventional eccentric screw pump

be used. Due to the so extended input and output

Outlet areas, the flow behavior of the pumped medium is improved.

The recesses 28 shrink continuously in the axial direction toward the center of the rotor-stator assembly 2 and the extent of the recesses 28 in the longitudinal direction corresponds in this embodiment, the stator pitch and the end portion of the invention 30 of the stator, as an area with non-required sealing lines , In the

shown lower rotor position and in the upper position of the rotor exist 3 delivery chambers, two open outer and one inner closed delivery chamber. If the rotor 10 moves away from this position, there is only one delivery chamber open to the pressure side and one to the suction side.

The two outer delivery chambers are sealed in the end region 30 only by half a sealing line surface, since the boundaries of the recesses 28 extend centrally of the sealing surfaces. In order to ensure a sufficient seal between the rotor 10 and To ensure stator is when introducing the friction-optimizing structure according to the invention

take into account that only half the sealing surface area as

Contact surface for a rotor-stator seal is available. In an elastomeric body 8 as shown in FIG. 4, the friction-optimizing recesses would have to be adapted accordingly in order to prevent the outer chambers from becoming leaky and from escaping via the recess 28. Alternatively, however, the recess 28 in the elastomer body 8 may be introduced along a sealing line boundary such that the

Contact area between the rotor 10 and elastomer body 8 corresponds to the entire sealing line region, ie the

Kontaktverhindernden recesses 28 have a smaller extent than the determined extent of the surface with the non-required sealing lines.

The elastomer body 8 seen in the longitudinal direction and without rotor is shown in Fig. 9. The determination of the end-side region according to the invention, in a 1/2 common rotor-stator arrangement, that is, with a single-rotor and a two-start stator, simplifies a formula possible. The end portion of the elastomer body 8, which is defined as an area with non-required sealing lines, is formed to prevent contact by making recesses in the body

Elastomer body 8 are introduced, which end of the

Elastomer body 8 begin and in cross section through the

Dimension L are marked. The dimension L at any point T in the end region in the longitudinal direction, can be calculated according to the formula:

L (T) = 4 * E * COS (T / Ps / 2 * Pi) where E is eccentricity and Ps is stator slope. Thus, for the stator at the point T = 0, the dimension L (T = 0) corresponds to 4 times the eccentricity. FIG. 9 shows a sectional view of the elastomer body 8 at the point T, which serves as the interface FF in FIG. 10

is drawn.

FIG. 10 shows the elastomer body 8 in a side view, with the variables L (T) and T entered for determining the geometry, where L is the dimension of the recess 28 in the end region 30 of the stator at the point T = 0

represents. The total of 4 recesses 28 ends in

Longitudinal direction of the stator 4, and the

Elastomer body 8, at T =% stator pitch (Ps).

1. A 1/2 common rotor-stator assembly 2 with a rotor 10, which is provided at the end with kontaktverhindernden recesses 28, Fig. 11. Since the rotor 10 is designed to prevent contact, both the friction between the rotor 10 and stator in total reduced, as well as the flow behavior, due to the increased flow cross-section in the end region of the rotor-stator assembly 2 can be improved. The rotor position shown represents a preferred position of the rotor 10 in the end region 30, in which a

Starting torque can be reduced by turning off the eccentric screw pump with such a rotor-stator assembly 2, which is designed to prevent contact in the end region 30, by means of a controllable or controllable

Drive device, the rotor 10 after switching off the

Eccentric screw pump is brought into a position in which there is no contact between the rotor 10 and stator 4, in particular between the rotor 2 and the elastomer body 8 in the end region 30. The rotor 10 removed from the stator of FIG. 11 is shown in FIG. 12, which is designed to prevent contact in an end-side region 30 which corresponds in the longitudinal direction to the gradient of the stator and which is defined as an area with sealing lines which are not required. This is achieved by a recess 28 in the rotor, which end in

Lengthwise towards the center of the rotor-stator assembly 2 continuously reduced. The rotor 10 has a basically circular cross section and starts at the end at the point T = 0 with a semicircular cross section.

FIG. 13 shows a side view of the rotor 10 with the contact-preventing recesses 28. The individual cross-sections through the rotor 10 at the distances ΊΊ = Τ ₂ = Τ ₃ = Τ ₄ = 1/8 * Ps are shown in FIGS. 14 a to 14 d , The bilateral recesses 28 extend in the longitudinal direction over the entire respective end region 30.

Fig. 14a shows the rotor cross-section with a

contact-preventing recess 28 of 135 ° at a distance ΊΊ = 1/8 * Ps, in Fig. 14b of 90 ° at a distance ΊΊ + Τ ₂ = 2/8 * PS, in Fig. 14c of 45 ° at a distance Ti + T ₂ + T ₃ = 3/8 * Ps and in Fig. 14d at a distance Ti + T ₂ + T ₃ + T ₄ = 4/8 * Ps the full rotor cross-section. The recess 28 decreases continuously in the longitudinal direction and ends at a distance which corresponds to Ps Ps.

A rotor-stator arrangement 2 with an end-side region 30, which is delimited in the longitudinal direction for the stator as an outer pump part at H and for the rotor 10 as an inner pump part at the gradient of the stator, is shown in FIG. 15. Rotor 10 and

Elastomer body 8 are provided with contact-preventing recesses 28 which extend in the longitudinal direction over the entire end-side region 30, on the suction and the pressure side of the rotor-stator assembly. In this embodiment allow the recesses 28 in particular a lateral arrangement of the inlet and outlet of the pump, and by the

Recesses 28 in the rotor 10 improves the

Flow behavior of the pumped medium by the

Flow cross-section between the rotor 10 and elastomer body 8 is increased. The friction between the rotor 10 and the stator is limited by the recesses 28 to a contact surface, which is required according to the invention for the operation of such a pump. Analogous to FIG. 11, a preferred

Position or position of the rotor 10 shown after switching off an eccentric screw pump with such a rotor-stator assembly 2.

The eccentric screw pump with the rotor-stator arrangement according to the invention is designed specifically for energy-efficient and low-wear operation. Due to the friction-optimized rotor-stator arrangement, the starting forces can be reduced to a minimum. With appropriate design of the

Recesses in the stator, a compact design compared to the known eccentric screw pumps without significant loss of power allows. In addition, the flow behavior is improved and the occurrence of cavitation counteracted.

LIST OF REFERENCE NUMBERS

2 rotor-stator arrangement

4 stator

6 stator jacket

8 elastomer body

10 rotor

12 delivery chamber

14a, b sealing lines

16 width range

18 friction-optimizing recess

20 friction-optimizing structure

22 core body

24 recesses forming structure

26 friction-optimizing structural surfaces

28 contact-preventing recess

30 end area

Claims

claims

1. eccentric screw pump having an inner and an outer pump part (10,4) as a rotor-stator assembly (2), with between the rotor (10) and stator (4) formed sealing lines (14a, b), wherein the outer pump part (4 ) in a sealing line width region (16) and / or at least one pump part (10, 4) in one

End region (30) of the rotor-stator assembly (2),

at least partially friction-optimized and / or at least one pump part (10,4) in the end region (30) at least

Partially formed contact preventing, wherein the

end region (30) is defined as an area with partially non-required sealing lines.

2. Eccentric screw pump according to claim 1, wherein at least one pump part (10,4) in the entire end region

is designed to prevent contact.

3. eccentric screw pump according to claim 1 or 2, wherein

at least one pump part (10,4) a friction-optimized

Surface has.

4. eccentric screw pump according to claim 3, wherein the

friction-optimized surface due to contact-reducing

Recesses (18) in the outer pump part (4) is formed.

5. Eccentric screw pump according to one of claims 1 to 4, wherein at least one pump part (10,4) in the end region (30) at least partially contact-preventing recesses (28).

6. Eccentric screw pump according to one of claims 1 to 5, wherein the outer pump part (4) by reducing a

Pre-tension friction optimized is formed.

7. Eccentric screw pump according to one of claims 1 to 6, wherein the friction-optimizing recesses (18) over the entire length of the outer pump part (4) are introduced.

8. Inner pump part (10), as part of a rotor-stator assembly (2) for an eccentric screw pump, which in a

end-side region (30) is at least partially friction-optimized and / or at least partially designed to prevent contact, wherein the end region (30) is defined as an area with partially impermeable sealing lines.

9. Outer pump part (4), as part of a rotor-stator assembly for an eccentric screw pump, which in a

Sealing line width range (16) is formed optimized friction and / or at least partially friction optimized in an end region (30) and / or at least partially

is designed to prevent contact, which is defined as an area with partially not required sealing lines.

10. Rotor-stator arrangement (2) with an inner pump part (10) according to claim 8 and an outer pump part (4) according to claim 9.

11. core body (22) for producing an outer pump part (4) according to claim 9, which corresponds in shape to the inner shape of the outer pump part (4) and in one

Sealing line width range (16) with a friction-optimizing recesses (18) forming structure (24) is provided.

12. Rotor-stator arrangement (2) for an eccentric screw pump having an inner and an outer pump part (10,4), wherein the outer pump part (4) has an inlet and / or outlet for a pumped medium, which extends radially outward extends and is formed in an end region (30) which is defined as a region with partially impermissible sealing lines.

13. A method for switching off an eccentric screw pump according to claim 1, which in an end region (30) an at least partially friction-optimized and / or

contact-preventing rotor-stator arrangement (2), in which by means of a controllable or controllable

Drive device, the rotor (10) after switching off the

Eccentric screw pump is brought into a position in which between the rotor (10) and stator (4) in the end region 30 at least partially no or a friction-optimized contact.