WO2018019318A1

WO2018019318A1 - Rotor/stator system with an inlet funnel for an eccentric screw pump

Info

Publication number: WO2018019318A1
Application number: PCT/DE2017/000219
Authority: WO
Inventors: Josef Strohhofer
Original assignee: Netzsch Pumpen & Systeme Gmbh
Priority date: 2016-07-26
Filing date: 2017-07-21
Publication date: 2018-02-01
Also published as: DE102016009028A1

Abstract

A rotor/stator system (12) for an eccentric screw pump (10) comprises a stator (14), which has a stator pitch and a screw thread-shaped inner circumferential surface (16) with N+l thread paths, and a rotor (18), which has a screw-shaped outer circumferential surface with N thread paths, wherein at least some sections of the rotor are received in the stator. The rotor/stator system additionally comprises a main section (20), in which a sealing line between the stator and the rotor is provided, and an inlet-side end section (22), which adjoins the main section and in which a sealing line-free inlet funnel (24) is formed between the stator (14) and the rotor (18) along a funnel length. The screw thread-shaped inner circumferential surface (16) of the stator (14) is formed both in the main section (20) as well as in the inlet-side end section (22).

Description

Rotor-stator system with an inlet funnel for an eccentric screw pump

The present invention relates to a rotor-stator system for an eccentric screw pump and an eccentric screw pump with such a rotor-stator system.

Eccentric screw pumps are known from the prior art and described for example in German Patent 602 107. They are used to promote a variety of media, in particular viscous, highly viscous and / or abrasive media, such as sludges, chemicals, adhesives, fats and petroleum.

Conventional progressing cavity pumps include a rotor-stator system connected to a drive in which a rotor is received in a stator and is rotatable eccentrically relative to the stator. By a helical design of the rotor and the formation of a helical Innenumfangsfiäche on the associated stator a number of delivery chambers are formed between the rotor and the stator, depending on the so-called number of stages of the rotor-stator system. By means of these delivery chambers, the medium to be delivered can be continuously transported in the direction of a Rotattonsache of the stator from an inlet region to an outlet region of the rotor-stator system and pressurized upon rotation of the rotor. Eccentric screw pumps are self-priming and can thus suck in operation the medium to be pumped from a feeder or a hopper.

However, the suction capacity of progressing cavity pumps is basically limited and moreover depends on different operating parameters, such as the speed of the rotor. To improve the suction capacity various design measures are known.

The document EP 1 522 729 A1 discloses an eccentric screw pump with a rotor-stator system, in which an expansion is provided in the inlet area of the rotor-stator system in order to facilitate the entry of a medium to be conveyed. Document EP 2 532 833 A1 proposes an eccentric screw pump with a rotor-stator system which comprises a first delivery volume and a second delivery volume, wherein the first delivery volume should be greater than the second delivery volume. As a result, the first stage of the rotor-stator system should act as a "booster" for the second stage.

However, such a rotor-stator system is difficult and to manufacture with a corresponding cost.

It is therefore an object of the present invention to appreciably verbes ^{¬ the} aspiration of an eccentric screw pump in the simplest possible way.

This object is achieved by a rotor-stator system with the features of claim 1 and an eccentric screw pump with the features of claim 14th

Preferred embodiments in the dependent claims 2 to 13 and the following description.

The rotor-stator system for an eccentric screw pump according to the invention comprises a stator having a stator pitch (the dimension of which is a length) and a helical inner peripheral surface with N + 1 pitches, and a rotor having a helical outer peripheral surface with N pitches, wherein the Rotor is at least partially received in the stator. Further, the rotor-stator system comprises a main portion in which a seal line between the stator and the rotor is present, and an inlet-side end portion adjacent to the main portion, in which a seal-free inlet funnel is formed between the stator and the rotor along a funnel length wherein the helical inner peripheral surface of the stator is formed in the main portion and in the inlet-side end portion.

Although the terms rotor and stator are used in the context of the invention, the rotor-stator system according to the invention is not limited to a drivable rotor. Rather, the invention relates to rotor-stator systems in which the rotor and / or the stator can be driven to produce a relative movement between the two. Thus, the rotor Stator system in addition to conventional tube stators also include wobblers, IFD stators, stators with uniform wall thickness and other stators.

The inner circumferential surface of the stator of the rotor-stator system according to the invention may be formed of an elastomer, while the rotor may be formed of a wear-resistant material, preferably metal.

Further, the Statorsteigung the stator can be twice as long as a rotor pitch of the rotor. In this context, it should be mentioned again that the person skilled in the art under the terms stator pitch and rotor pitch each one

Length is understood and this term is used accordingly in the context of the present invention.

The inventor of the present invention has recognized that advantageous flow effects can be achieved by means of an inlet funnel between the stator and the rotor which, on the one hand, comprises a continuation of the helical inner peripheral surface of the stator and, on the other hand, is impermeable to seal. In particular, these measures significantly reduce the flow-side flow pressure losses, which results in a correspondingly improved intake capacity. To achieve this advantageous effect can already be sufficient funnel length, which is less than the length of a stage of the associated rotor-stator system. For example, with a feed hopper according to the invention, which has a funnel length of 10% of a step length, appreciable fluidic improvements over the prior art can be achieved. By the

helical formation of the inner circumferential surface of the stator in the region of the inlet funnel, the medium to be conveyed, before the medium reaches the main portion and forms a closed delivery volume, already placed in a movement which substantially corresponds to its movement in the main portion of the rotor-stator system. In contrast to conventional rotor-stator systems with widenings in the inlet region, by forming an oil funnel according to the invention between the stator and the rotor, inlet flow losses can be reduced, which increases the efficiency of eccentric worm pumps with a rotor-stator system according to the invention.

In one embodiment of the invention, the inlet funnel is formed by a funnel-shaped widening of the helical inner circumferential surface in the inlet-side end section. Thus, in this embodiment, the helical inner peripheral surface of the stator is seated in the main portion is formed, in the funnel-shaped widening of the inlet-side end portion away. The formation of the helical inner peripheral surface in the inlet side end portion substantially corresponds to the formation of the helical inner peripheral surface in the main portion, for example, with respect to the rotational direction and pitch of the screw flights. However, due to the funnel-shaped widening in the end portion, the helical inner peripheral surfaces of the main portion and the end portion in this embodiment differ in their opening cross section. The maximum widening of the helical inner peripheral surface is provided at the inlet or in the vicinity of the inlet, whereas the minimum widening is formed in a region of the end portion adjoining the main portion. The rotor may have a constant cross-sectional area in the main portion and the inlet-side end portion in this embodiment, but no seal line is provided in the inlet funnel between the stator and the rotor.

According to one embodiment of the invention, the funnel length can be in a range of 1% to 20%, preferably 2% to 15% of the stator pitch. Such funnel lengths are already sufficient to reduce flow losses in the inlet area of the rotor-stator system.

The stator has in the region of the inlet funnel an inlet opening and an inlet opening opposite, adjacent to the main section outlet opening. Preferably, a cross-sectional geometry of the inlet opening substantially corresponds to a cross-sectional geometry of the outlet opening, wherein the position of the inlet opening is rotated relative to the position of the outlet opening about an axis of rotation of the stator. The outlet opening of the inlet funnel of the stator which adjoins the main section may be identical in its position and cross-sectional geometry to the opening of the main section formed by the inner circumferential surface of the stator, which adjoins this outlet opening. It is understood that the term of the cross-sectional geometry of the inlet opening and the outlet opening refers to the shape of the respective opening. However, the respective dimensions of the cross-sectional geometries of the inlet opening and the outlet opening may differ from one another, for example in the case of a funnel-shaped widening of the helical inner circumferential surface in the inlet-side end section.

As described above, in this embodiment of the invention, the position of the inlet opening is rotated relative to the position of the outlet opening of the inlet funnel about an axis of rotation of the stator. The associated twist angle can be particularly depending on the funnel length and the stator pitch. Thus, for the angle of rotation between the position of the inlet opening and the position of the outlet opening about an axis of rotation of the stator the relationship applies: a _s = T / H _s x 360 °, where äs the angle of rotation between the position of the inlet opening and the position of the outlet opening to the axis of rotation of the stator, T is the funnel length of the inlet funnel and Hs is the stator pitch.

In preferred embodiments of the invention, the cross-sectional geometry of the outlet opening is in the form of a first elongated hole having a first width and a first length, while the cross-sectional geometry of the inlet opening has the shape of a second elongated hole having a second width and a second length, wherein the second width is greater than the first width and the second length is greater than the first length. Such a form of the cross-sectional geometries of the inlet opening and the outlet opening of the inlet funnel may be provided especially in 1-2-speed rotor-stator systems, i. a system with a 2-speed stator and a 1-speed rotor. In this case, the rotor may have a circular cross-section.

In the embodiment described above, the relationship can apply to the rotor-stator system according to the invention:

Wl = arctan ((B ₂ -Bi) / T), where Wi may be in a range of 5 ° to 50 °, preferably in a range of 12 ° to 40 ° and where B _{2 is} the second width of the second slot, Bi the first width of the first slot and T is the funnel length of the inlet funnel.

In addition or alternatively, in the embodiment described above, the relationship for the rotor-stator system according to the invention may be the following:

W ₂ = arctane ((H ₂ -H / T), where W _{2 may be} in a range of 5 ^P to 50 °, preferably in a range of 12 ° to 14 °, and H _{2 is} the second length of the second slot, Hi is the first length of the first slot and T is the funnel length of the inlet funnel. In other preferred embodiments of the invention, the cross-sectional geometry of the exit opening has substantially the shape of a first triangle with rounded corners, and the cross-sectional geometry of the entry opening has substantially the shape of a second triangle with rounded corners. The second triangle may have a larger area than the first triangle. Such cross-sectional geometries can be provided in particular for 2-3-speed rotor-stator systems, ie a system with a 3-speed stator and a

2-speed rotor.

It is understood that the rotor-stator system according to the invention is neither limited to 1-2-speed nor to 2-3-speed systems. Rather, the rotor-stator system according to the invention can be designed as any N-M-common system. For this N-M-standard rotor-stator system, the relationship applies:

M = IM + 1, where M is the number of threads of the stator and N is the number of threads of the rotor.

According to the invention, the inlet funnel between the rotor and the stator can also be formed by a substantially inversely funnel-shaped reduction in cross-section of the rotor in the inlet-side end section. In this case, the helical stator may have a constant opening cross section in the main portion and the inlet side end portion, yet the desired funnel shape is formed in the inlet side end portion between the rotor and the stator by the inversely funnel-shaped reduction in the cross section of the rotor. Both embodiments may also be combined, ie, in addition to the reduction in the cross section of the rotor, a widening (or even a reduction) of the helical stator cross section may be formed in the region of the inlet-side end section. Regardless of the design of the helical stator in the region of the inlet-side end portion, according to the invention, there is always a seal line clearance between the rotor and the stator in the region of the inlet funnel. A maximum reduction in the diameter of the rotor can be formed in particular on the inlet side of the rotor-stator system, while a minimum reduction in the diameter of the rotor can be formed in a region of the end section of the rotor-stator system adjoining the main section. The rotor of the rotor-stator system according to the invention has an inlet-side cross-section in the region of the inlet-side end section and an outlet-side cross-section which is opposite to the inlet-side cross-section and adjoins the main section of the rotor-stator system. Preferably, a geometry of the inlet-side cross-section substantially corresponds to a geometry of the exit-side cross-section, wherein the inlet-side cross-section is rotated relative to the exit-side cross-section about the axis of rotation of the rotor. The axis of rotation of the rotor describes the longitudinal axis of the rotor about which the helical outer peripheral surface of the rotor is coiled, ie the longitudinal axis passing through the center of an enveloping circle formed by the helical outer circumferential surface of the rotor. Again, it is understood that the term geometry refers to the shape of the inlet-side cross-section and the exit-side cross-section, wherein the dimensions of the inlet-side cross-section may differ from the dimensions of the exit-side cross-section, for example due to the inversely funnel-shaped cross-sectional reduction of the rotor. The inlet-side as well as the outlet-side cross-section may in particular be circular. Furthermore, the rotation of the inlet-side cross-section relative to the outlet-side cross section of the rotor about the axis of rotation of the rotor can be selected as a function of the associated funnel length and the rotor pitch.

In particular, for the angle of rotation between the outlet-side cross-section and the inlet-side cross-section of the rotor in the region of the inlet-side end section, the following relationship applies: a _R = T / H _R x 360 °, where a _{R is} the angle of rotation between the outlet-side cross-section and the inlet-side cross-section the axis of rotation of the rotor, T is the funnel length and H _{R is} the rotor pitch.

In preferred embodiments, the inlet funnel and an adjoining peripheral surface of the rotor-stator system can merge substantially edge-free into each other. In other words, each point of a transition between the inlet funnel and an adjacent circumferential surface of the rotor-stator system is then differentiable. Depending on whether the inlet funnel is formed by an expansion of the stator and / or a reduction of the rotor, this differentiable transition can be formed on the stator and / or the rotor. An edge-free or differentiable transition can conditions in the inlet area of the rotor-stator system by further reducing pressure losses.

According to one development of the invention, at least one rounded surface section can be formed on a longitudinal end of the inlet funnel. Also, a plurality of rounded surface portions may be formed at the inlet end of the inlet funnel, which ensure a flow as possible lossless transition between a feed cross section and the inlet funnel. Furthermore, these rounded surface portions as a

fluidically optimized transition to be located on the inlet side configured to the inlet funnel ^¬ subsequent conventional expansion of the rotor-stator system.

The invention also relates to an eccentric screw pump which is equipped with a rotor-stator system of the type described above. The eccentric screw pump may further comprise a drive device connected to the rotor and / or the stator, by means of which the rotor and / or the stator can be set in rotation, and a supply line device connected to the stator on the inlet side.

Preferred embodiments of the invention will be explained in more detail with reference to the accompanying schematic drawings. They show:

Figure 1 is a sectional view of an eccentric screw pump with a rotor-stator system according to the invention;

Figure 2 is a sectional view of a stator of the rotor-stator system according to the invention according to a first embodiment;

Figure 3 is a plan view of an inlet side end face of the invention

Rotor-stator system according to the first embodiment;

Figure 4 is a sectional view of a stator of the rotor-stator system according to the invention according to a second embodiment;

Figure 5 is a plan view of an inlet side end face of the invention

Rotor-stator system according to the second embodiment; Figure 6 is a side view of a rotor of the rotor-stator system according to the invention according to a third embodiment;

Figure 7 is a plan view of an inlet side end face of the rotor of Figure 6;

Figure 8 is a sectional view of a stator of the rotor-stator system according to the invention according to a fourth embodiment;

Figure 9 is a side view of a rotor of the rotor-stator system according to the invention according to a fifth embodiment;

Figure 10 is a perspective sectional view of a stator of the rotor-stator system according to the invention according to a sixth embodiment; and

Figure 11 is a side view of a rotor of the rotor-stator system according to the invention according to a seventh embodiment.

Figure 1 shows a sectional view of an eccentric screw pump 10, which is equipped with a rotor-stator system 12 according to the invention. The rotor-stator system 12 includes a stator 14 having a helical inner peripheral surface 16 made of an elastic material and a rigid shell 17 surrounding the inner peripheral surface. The helical inner peripheral surface 16 of the stator 14 is shown in Figure 1 with two flights. It will be understood, however, that in other embodiments of the invention, the inner peripheral surface 16 may have any number of threads. Further exemplary embodiments of stators according to the invention with a defined number of threads are shown in the further figures.

The rotor-stator system 12 further includes a rotor 18, which is received for the most part in the stator 14 and has a helical outer peripheral surface. The helical outer peripheral surface of the rotor 18 is shown in Figure 1 with a thread. It is understood, however, that the outer peripheral surface of the rotor 18 may have more threads in other embodiments of the invention. Further exemplary embodiments

Rotors according to the invention with a defined number of threads are likewise to be found in the further figures. The rotor-stator system 12 has a main portion 20 in which, regardless of the relative position of the rotor 18 to the stator 14 has a substantially longitudinal sealing line between the Innenumfangsfiäche 16 of the stator and the outer peripheral surface of the rotor 18 is present. Adjacent to the main portion 20 is located on the inlet side of the rotor-stator system 12, an inlet-side end portion 22. In this inlet-side end portion 22 between the stator 14 and the rotor 18, a seal-free inlet funnel 24 is formed, ie, regardless of the relative position of the Rotor 18 and the stator 14 to each other is therefore in the region of the inlet funnel 24 no sealing line between the rotor 18 and stator 14 is present.

The rotor 18 is connected axially outside the stator 14 via a propeller shaft 26 to a drive shaft 28 of a drive device 30. The propeller shaft 26 is arranged in the region of a supply line device 32, which comprises an opening 34 for Beschi ^¬ cken the eccentric screw pump 10. On the outlet side, the rotor-stator system 12 is connected to a downstream device 36, which is not shown in FIG. 1 and can be configured as desired.

By rotating the drive shaft 28 of the drive device 30, the rotor 18 is moved by means of the propeller shaft 26 eccentrically relative to the stator 14. Due to the presence of the sealing line between the stator 14 and the rotor 18 in the main portion 20, delivery volumes trapped between the rotor 18 and the inner peripheral surface 16 of the stator 14 are transferred from an inlet side 38 of the rotor-stator system 12 to an outlet side 40 of the rotor-stator system 12 transported. In this case, the eccentric screw pump 10 sucks in a medium to be conveyed on the inlet side 38 of the rotor-stator system 12 and builds a pressure in the downstream device 36 on the outlet side. The close-coupled inlet hopper 24, which includes a portion of the helical inner peripheral surface 16 of the stator 14, reduces the flow pressure loss at the inlet side 38 of the rotor-stator system 12, thereby increasing the suction capacity of the eccentric screw pump 10.

In the figures described below, identical or comparable or equivalent components and features are provided with the same reference numerals. The components and features, which are not described again with reference to the other features, are similar in their design and function to the corresponding components and features according to the respective previously described figures. It should be mentioned with regard to the following values that the scales between the different figures can vary.

2 shows a stator 14 of the rotor-stator system 12 according to the invention of a first embodiment, with a stator rotation axis Rs. In the example shown, the helical inner peripheral surface 16 has two threads which are located both in the region of the main section 20 and in the region of the end section 22 are formed. In this first embodiment of the rotor-stator system according to the invention is therefore a so-called 1-2-speed system, the 1-speed rotor is not shown here.

As can be clearly seen in Figure 2, the helical inner peripheral surface 16 of the stator 14 in the end portion 22 is expanded toward the inlet side 38 approximately funnel-shaped, thus forming an inlet funnel 24 between the stator 14 and the rotor (not shown). The funnel-shaped widening of the inner circumferential surface 16 is selected such that no sealing line exists between the stator 14 or the helical inner circumferential surface 16 and the rotor (not shown) in the region of the end section 22.

As can also be seen from Figure 2, the funnel length T of the inlet funnel 24 in the embodiment shown about 6% of the stator slope H _s , the skilled person understands the terms stator slope and rotor pitch each a length specification.

FIG. 3 shows an inlet-side end view of the rotor-stator system 12 according to the invention in accordance with the first embodiment shown in FIG. In contrast to Figure 2, however, in addition to the stator 14 and the rotor 18 received therein is shown in a sectional view in Figure 3. The stator 14, more specifically, the helical inner peripheral surface 16 of the stator 14, has an inlet opening 42 and an outlet opening 44, each having the shape of a slot. In the example shown, the inlet opening 42 is the opening of the inlet funnel 24 formed on the inlet side of the rotor-stator system 12. The outlet opening 44 is arranged opposite to the inlet opening 42 and represents the opening of the inlet funnel 24 which is connected to the main section 20 of the rotor Stator system 12 adjacent.

The inlet funnel 24 extends in FIG. 3 from the inlet opening 42 to the outlet opening 44, wherein it can be seen that the helical shape of the interior Peripheral surface 16 of the stator 14 is continued in the region of the inlet funnel 24.

The outlet opening 44 has a first width Bi and a first length Hi, while the inlet opening 42 has a second width B ₂ and a second length H ₂ . The second width B ₂ in the embodiment shown is greater than the first width Bi and the second length H ₂ is greater than the first length Hi in the illustrated embodiment. Furthermore, it can be seen in FIG. 3 that the position of the inlet opening 42 is rotated relative to the position of the outlet opening 44 about an axis of rotation Rs of the stator 14.

A twist angle asi between the position of the inlet opening 42 and the position of the outlet opening 44 is approximately 22 ° in the illustrated embodiment.

Furthermore, for the relationship between the widths of the inlet opening and the outlet opening in the embodiment shown here:

Wi = arctan ((B ₂ -B / T) = 33 °, where B _{2 is} the second width of the slot of the inlet opening 42, Bi is the first width of the slot of the outlet opening 44 and T is the funnel length of the inlet funnel 24.

Furthermore, for the relationship between the lengths of the inlet opening and the outlet opening in the embodiment shown here:

W ₂ = arctan ((H ₂ - Hi) / T) = 33 °, where H _{2 is} the second length of the slot of the inlet opening 42, Hi the first length of the slot of the outlet opening 44 and T is the funnel length of the inlet funnel 24.

FIG. 4 shows a sectional illustration of a stator 114 of the rotor-stator system according to the invention in accordance with a second embodiment, wherein a representation of the rotor has also been dispensed with here. In contrast to the embodiment of the stator 14 shown in FIG. 2, the stator 114 of the second embodiment has an additional third thread. The second embodiment of the rotor-stator system according to the invention is therefore a so-called 2-3-speed system. The three-flighted helical inner peripheral surface 116 The stator 114 also extends beyond the main section 120 into the end section 122 of the rotor-stator system and is thus also formed in the region of the inlet funnel 124.

Analogous to the first embodiment, the inlet funnel 124 is also formed in the second embodiment according to Figure 4 by an approximately funnel-shaped widening of the helical inner peripheral surface 116 in the inlet-side end portion 122 between the stator 114 and the rotor (not shown). Again, in all relative positions between the rotor and the stator in the region of the inlet funnel 124, there is never a sealing line between the rotor and the stator.

The funnel length T is also about 6% of the stator pitch H _s in the second embodiment.

FIG. 5 shows an inlet-side end view of the rotor-stator system 112 according to the invention of the second embodiment with the stator 114 shown in FIG. 4 and a rotor 118 received therein, which is shown in a sectional view. The inlet opening 142 and the outlet opening 144 of the stator 114 in the example shown each have a substantially triangular cross-sectional geometry with rounded corners. Due to the funnel-shaped widening of the helical inner peripheral surface 116 of the stator 114 in the region of

Inlet funnel 124 is the inlet opening 142 larger than the outlet opening 144th

A twist angle as2 between the position of the inlet opening 142 and the position of the outlet opening 144 in the illustrated embodiment is again about 22 °.

FIG. 6 shows a schematic view of a rotor 218 of the rotor-stator system according to the invention of a third embodiment of the invention, which has a helical outer peripheral surface. The rotor 218 has a rotor axis RR. In the inlet-side end section 222 of the rotor-stator system, a funnel-shaped reduction in cross section is formed on the rotor 218 in the opposite direction of flow. More specifically, the cross section of the rotor 218 in the inlet side end portion 222 progressively decreases from the main portion 220 of the rotor-stator system 212 toward the inlet side 238. This reduction in the cross-section of the rotor 218 thus forms the inlet funnel 224 between the rotor 218 and the stator (not shown) in the illustrated third embodiment of the invention. Thus, in this third embodiment of the invention, it is possible to use a stator which does not have an extension of the helical inner peripheral surface in the inlet side end portion 222 of the rotor-stator system but has a substantially constant inner circumference. However, it is understood that regardless of the choice of the stator used with the rotor 218, the helical shape of the inner circumferential surface of the stator is also formed in the region of the inlet-side end portion 222 and thus in the region of the inlet funnel 224.

FIG. 7 shows an inlet-side end view of the rotor 218 of the rotor-stator system according to the third embodiment of the invention shown in FIG. The rotor 218 has an inlet-side cross-section 250 in the region of the inlet-side end portion 222 and an outlet-side cross-section 252 opposite the inlet-side cross-section 250, which adjoins the main portion 220 of the rotor-stator system. The inlet funnel 224 extends between the inlet-side cross-section 250 and the outlet-side cross-section 252. FIG. 7 also shows an enveloping circle 254 of the rotor 218 which is generated in operation by the eccentric movement of the rotor 218 from the outer circumferential surface of the rotor 218.

Both the inlet-side and outlet-side cross-section of the rotor 218 is circular in the embodiment shown, wherein the inlet-side cross-section 250 has a smaller area than the outlet-side cross-section 252 due to the inversely funnel-shaped reduction in cross-section of the rotor 218.

Furthermore, the inlet-side cross-section 250 and the outlet-side cross-section 252 are rotated relative to each other about an axis of rotation RR of the rotor 218. The twist angle QR is determined by the ratio of the funnel length T and the rotor pitch HR and is approximately 60 ° in the illustrated embodiment.

FIG. 8 shows a sectional view of a stator 314 according to a fourth embodiment of the rotor-stator system according to the invention. The stator 314 essentially corresponds to the stator 14 of the first shown in FIG

Embodiment of the rotor-stator system 112. In addition to the features of the stator 14 of the first embodiment of the invention, the stator 314 of the fourth embodiment of the invention has a differentiable transition of the helical inner peripheral surface 316 in the region of the inlet funnel 324 to the adjacent thereto, helical inner peripheral surface 316 of the stator 314 in the region of the main portion 320 on. In other words, the inlet funnel 324, which in the embodiment shown is formed by the widening of the inner circumferential surface 316, and the adjoining inner circumferential surface 316 of the stator 314 in the region of the main section 320 essentially merge into one another without edges. Such a transition has additional beneficial effects on the flow conditions in the region of the inlet funnel 324 and contributes to a further improvement in the suction capacity of a corresponding eccentric screw pump.

A rotor 418 according to a fifth embodiment of the rotor-stator system according to the invention is shown in FIG. The rotor 418 substantially corresponds to the rotor of the third embodiment of the invention shown in FIG. In addition to the features of the rotor of the third embodiment, the rotor 418 according to the fifth embodiment shown in FIG. 9 has a differentiable transition in the region of the inlet funnel 424 between the portion of the rotor 418 forming the inlet funnel 324 and the main portion 420 of the rotor 418 adjacent thereto. In other words, the cross-section-reduced region of the rotor 418 merges substantially edge-free into the main section of the rotor 418. In this fifth embodiment too, the edge-free transition between the inlet funnel 424 and the main section 420 of the rotor-stator system can additionally reduce the flow pressure losses in this area and thus further increase the intake capacity of a corresponding eccentric screw pump.

FIG. 10 shows a perspective sectional view of a stator 514 according to a sixth embodiment of the rotor-stator system according to the invention. The stator 514 of the sixth embodiment of the invention substantially corresponds to the stator 14 shown in FIG. 2 of the first embodiment of the rotor-stator system 12 according to the present invention. In addition to the features of the stator 14 of the first embodiment, the stator 514 according to the sixth embodiment includes a fluidic one optimized transition at its inlet end adapted to a connected lead portion (not shown).

More specifically, in the region of the inlet funnel 524 on the inlet side 538, the stator 514 has variously formed, rounded surface portions 556. By forming these rounded surface portions 556, it is possible to achieve a uniform transition to the feed cross section, which is in line with the rotor Stator system 512 is connected, whereby flow pressure losses in the inlet region of the rotor-stator system 512 can be further minimized.

FIG. 11 shows a rotor 618 of a rotor-stator system according to a seventh embodiment of the invention. The rotor 618 shown in FIG. 11 is similar to the rotor 218 of the rotor-stator system 212 of the third embodiment shown in FIG. In addition to the technical features of the rotor 218 of the third embodiment of the invention, the rotor 618 according to the seventh embodiment of the invention has variously formed rounded surface portions 656 at an entrance end of the inlet funnel 624 formed by the cross-sectional reduced rotor 618. These rounded surface portions 656 are adapted depending on the geometry of the rotor 618 and the surrounding components, such as the associated stator and a feed cross-section connected to the rotor-stator system. By means of a suitable structural adaptation, the rounded surface sections 656 improve the flow conditions in the inlet region of the rotor-stator system according to the invention. As a result, the intake capacity of the associated eccentric screw pump can be further improved by this seventh embodiment of the rotor-stator system according to the invention.

It should be understood that the above-described exemplary embodiments of the invention are not exhaustive and do not limit the scope of the invention. In particular, it will be apparent to those skilled in the art that they may combine the features of the various embodiments and / or omit various features of the embodiments without departing from the subject matter of the invention.

Claims

claims

1. Rotor-stator system (12) for an eccentric screw pump (10), with

a stator (14, 114, 314, 514) having a stator pitch (H _s ) and a helical inner peripheral surface (16, 116, 316, 516) having N + 1 pitches,

a rotor (18, 118, 218, 418, 618) having a helical outer circumferential surface with N threads, wherein the rotor (18, 118, 218, 418, 618) at least partially in the stator (14, 114, 314 , 514), a main portion (20, 120, 220, 320, 420, 520, 620) in which a sealing line between the stator (14, 114, 314, 514) and the rotor (18, 118, 218, 418, 618), and

a inlet-side end portion (22, 122, 222, 322, 422, 522, 622) adjacent to the main portion (20, 120, 220, 320, 420, 520, 620), in which a leak-free inlet funnel (24, 124, 224 , 324, 424, 524, 624) is formed between the stator (14, 114, 314, 514) and the rotor (18, 118, 218, 418, 618) along a funnel length (T), the helical inner peripheral surface (16 , 116, 316, 516) of the stator (14, 114, 314, 514) in the main portion (20, 120, 220, 320, 420, 520, 620) and the inlet end portion (22, 122, 222, 322, 422) , 522, 622) is formed.

2. Rotor-stator system (12) according to claim 1,

characterized in that the inlet funnel (24, 124, 324, 524) is formed by a funnel-shaped widening of the helical inner peripheral surface (16, 116, 316, 516) in the inlet-side end portion (22, 122, 322, 522).

3. rotor-stator system (12) according to claim 1 or 2,

characterized in that the funnel length (T) is in a range of 1% to 20%, preferably 2% to 15% of the stator pitch (H _s ).

4. Rotor-stator system (12) according to any one of the preceding claims, characterized in that the stator (14, 114) in the region of the inlet funnel (24, 124) has an inlet opening (42, 142) and one of the inlet opening (42, 142) opposite, to the main portion (20, 120) adjacent the outlet opening (44, 144), wherein a cross-sectional geometry of the inlet opening (42, 142) substantially a cross-sectional geometry of the outlet opening (44, 144) speaks, and wherein the position of the inlet opening (42, 142) relative to the position of the outlet opening (44, 144) about an axis of rotation (Rs) of the stator (14, 114) is rotated.

5. rotor-stator system (12) according to claim 4,

characterized in that the cross-sectional geometry of the outlet opening (44) has the shape of a first elongated hole having a first width (Bi) and a first length (Ht) and the cross-sectional geometry of the inlet opening (42) has the shape of a second elongated hole having a second width (B ₂ ) and a second length (H ₂ ), wherein the second width (B ₂ ) is greater than the first width (Bi) and the second length (H ₂ ) is greater than the first length (H0).

6. rotor-stator system (12) according to claim 5,

characterized in that the system (12) has the following relationship: arctan ((B ₂ - Bi) / T) = Wi, where Wi is in a range of 5 ° to 50 °, preferably in a range of 12 ° to 40 ° °, and wherein B _{2 is} the second width of the second slot, Bi is the first width of the first slot and T is the funnel length of the inlet funnel (24).

7. rotor-stator system (12) according to claim 5 or 6,

characterized in that the following relationship applies to the system (12): arctane ((H ₂ - Hi) / T) = W ₂ , where W _{2 is} in a range of 5 ° to 50 °, preferably in a range of 12 ° to 40 °, and where H _{2 is} the second length of the second slot, Hi is the first length of the first slot and T is the funnel length of the inlet funnel (24).

8. rotor-stator system (12) according to claim 4,

characterized in that the cross-sectional geometry of the exit opening (144) has substantially the shape of a first triangle with rounded corners and the cross-sectional geometry of the entrance opening (142) has substantially the shape of a second triangle with rounded corners.

9. rotor-stator system (12) according to claim 8, characterized in that the second triangle has a larger area than the first triangle.

Rotor-stator system (12) according to one of the preceding claims, characterized in that the inlet funnel (224, 424, 624) by an inversely funnel-shaped reduction in cross-section of the rotor (218, 418, 618) in the inlet-side end portion (222, 422, 622) is formed.

11. Rotor-stator system (12) according to claim 10,

characterized in that the rotor (218) in the region of the inlet funnel (224) has an entrance-side cross-section (250) and an exit-side cross-section (252) which is opposite to the entry-side cross-section (250) and adjoins the main section (220) of the rotor-stator system ), wherein a geometry of the entry-side cross-section (250) substantially corresponds to a geometry of the exit-side cross-section (252) and wherein the entry-side cross-section (250) relative to the exit-side cross-section (252) about an axis of rotation (RR) of the rotor (218). is twisted.

12. Rotor-stator system (12) according to any one of the preceding claims, characterized in that the inlet funnel (324, 424) and an adjoining peripheral surface of the rotor-stator system merge without edges into one another.

13. Rotor-stator system (12) according to any one of the preceding claims, characterized in that at an inlet-side end of the inlet funnel (524, 624) at least one rounded surface portion (556, 656) is formed.

14. eccentric screw pump (10), with

a rotor-stator system (12) according to one of the preceding claims, a drive device (30) connected to the rotor (18, 118, 218, 418, 618) and / or the stator (14, 114, 314, 514), by means of which the rotor (18, 118, 218, 418, 618) and / or the stator (14, 114, 314, 514) is set into rotation, and an inlet side connected to the stator (14, 114, 314, 514) Supply line device (32).