Eccentric screw pump

Abstract

The invention relates to a progressive cavity pump, comprising at least a stator (1), a rotor (2), which rotates in the stator, a drive (3) for the rotor, a pump housing (4), which is connected to the stator (1) and which has at least one inlet or outlet opening (6) for the medium to be pumped, a connection housing (14), which is arranged between the pump housing (4) and the drive (3) and which is open or is to be opened, a connection shaft (9), which is detachably connected to the drive (3) and which is at least partly arranged in the connection housing (14). The connection shaft (9) is sealed by means of a (preferably single-acting) slide ring seal (13) in order to separate the pump housing (4) liquid-tight from the surroundings or from the connection housing. The slide ring seal (13) has a seal housing (18), which is fastened to the pump housing (4) and / or the connection housing (14), a slide ring (19), which is fastened to the connection shaft (9) for conjoint rotation and rotates in the seal housing (18), and a stationary counter ring (20), which is fastened to the seal housing (18). The pump is characterized in that the seal housing (18) is designed as a divided seal housing and comprises a main housing (18a), which in the assembled state surrounds the slide ring (19) and is fastened to the pump housing (4) and / or the connection housing (14), and a housing cover (18b), which bears the counter ring (20) and is detachably fastened to the main housing (18a) and can be separated therefrom.

Description

[0001] The invention relates to an eccentric screw pump with at least a stator, a rotor rotating in the stator, a drive for the rotor, a pump housing (e.g. suction housing) connected to the stator (e.g. suction side) which has at least one inlet or outlet opening for the medium to be pumped, an open or openable connecting housing arranged between the pump housing and the drive, a connecting shaft detachably connected to the drive which is arranged at least partially in the connecting housing, wherein the connecting shaft (for liquid-tight separation of the pump housing from the environment or from the open or to-be-opened connecting housing) is sealed with a mechanical seal, wherein the mechanical seal comprises a sealing housing attached to the pump housing and / or the connecting housing, a sliding ring fixed to the shaft and rotating in the sealing housing, and a stationary counter ring attached to the sealing housing.

[0002] An eccentric screw pump is a type of rotary positive displacement pump used to pump a wide variety of media, particularly highly viscous liquids, in diverse industrial sectors. These liquids can also contain solids.

[0003] The stator is preferably made of elastic or elastomeric material and is generally surrounded by a one-piece or multi-piece stator casing or housing. Alternatively, stators made of other materials, e.g., metal, are also used. The pump housing connected to the stator on the suction side is generally referred to as the suction housing, and the housing connected to the stator on the pressure side, e.g., as the pressure port. However, it is also possible to operate such a pump in the opposite direction of flow, in which case the suction housing (as the pump housing) would be located on the pressure side. Therefore, within the scope of the invention, the designation of the pump housing as a suction housing is independent of the actual flow direction. This is the housing located between the stator and the drive. The rotating connection between the drive and the stator, which simultaneously ensures eccentricity, is called the suction housing.The connection between the connecting shaft on the one hand and the rotor on the other is achieved via a coupling rod arranged in the pump housing, which is connected, for example, to the connecting shaft via a drive-side joint and to the rotor via a rotor-side joint. Alternatively, the eccentricity can also be achieved by other means (i.e., without joints), for example, by a flexible / flexible coupling rod. Coupling rod thus refers to an element that ensures the eccentricity of the rotor or enables the eccentric movement between the rotating connecting shaft and the rotor. It is also fundamentally within the scope of the invention for this coupling rod to be formed integrally with the connecting shaft and / or integrally with the rotor.The connecting shaft, also known as a plug shaft, is typically connected directly to the drive's output shaft and serves as a link between the drive's output shaft and the pump's power transmission components. The connecting housing located between the pump housing (suction housing) and the drive is commonly referred to as a "lantern" or "bracket." This housing serves, for example, to accommodate, secure, and support the pump housing on one side and the drive on the other. This connecting housing, or lantern, is typically mounted on a base plate or directly on a foundation, supporting and carrying both the drive and the pump housing. Suspended configurations are also possible. In these cases, the connecting housing is designed as an open housing, or at least as one that can be opened, meaning it is accessible from the outside through an opening.Preferably, the connecting housing is a separate housing from the pump housing, so that, for example, the pump housing is attached to the connecting housing by means of screws or the like. However, the invention also encompasses embodiments in which the pump housing and connecting housing are formed as a single piece and are therefore inseparable from one another.

[0004] For the operation of the progressive cavity pump, it is usually installed in a (pipe) piping system, so that, for example, a suction line is connected to the suction housing (i.e., the inlet or outlet opening) and a pressure line is connected to the pressure port of the pump.

[0005] The stator of the progressive cavity pump can be designed as a longitudinally split stator consisting of at least two stator shells, e.g., stator half-shells. Furthermore, the stator can be replaceable separately from the stator shell and consequently not rigidly, and in particular not metallurgically, connected to the stator shell. This allows the elastomeric stator to be replaced separately from the stator shell without requiring complex disassembly of the pump. The stator shell consists, for example, of at least two shell segments, which, as clamping segments, form a stator clamping device with which the stator can be clamped radially against the rotor. The stator shell can consist of, for example, three or four shell segments forming the stator clamping device. A progressive cavity pump of this type is known, for example, from WO 2009 / 024279 A1 or DE 10 2014 112 550 B4.

[0006] Furthermore, an eccentric screw pump with rotor separation is known from EP 2 428 680 B1. In this design, the rotor is detachably connected to the coupling joint or a joint component thereof without disassembling the coupling joint. Such pumps with rotor separation are also included in a preferred embodiment of the invention.

[0007] To ensure a liquid-tight seal between the pump housing and the environment, or between the open or to-be-opened connecting housing, the connecting shaft is sealed with a (preferably single-acting) mechanical seal. Such a mechanical seal is subject to wear and must therefore be replaced or repaired as a consumable part when necessary. For this purpose, with eccentric screw pumps commonly used in practice, it is generally necessary to remove the pump housing (suction housing) and, if applicable, the suction line connected to the inlet or outlet of the pump housing. Only then can the mechanical seal be removed. The installation of the mechanical seal also requires...Replacing a mechanical seal with its housing is only possible with the suction housing and suction line removed, as otherwise, inserting the drive shaft through the housing could damage the stationary counter ring of the mechanical seal. Therefore, there is a need to simplify the replacement and maintenance of the mechanical seal on such a progressive cavity pump.

[0008] A generic eccentric screw pump is also known from DE 102005 039 618 A1. In the known pump, the disassembly, particularly of the rotor unit, e.g., for cleaning purposes, is intended to be facilitated. For this purpose, the rotor drive shaft is arranged inside a hollow shaft that passes through the sealing unit.

[0009] The invention is based on the objective of creating an eccentric screw pump of the type described above, which, despite its simple design, is characterized by optimized maintenance and repair options, particularly in the area of ​​the mechanical seal.

[0010] To solve this problem, the invention teaches an eccentric screw pump with the features of claim 1. It is provided that the sealing housing of the mechanical seal is designed as an (axially) split sealing housing and comprises, on the one hand, a base housing which, in the assembled state, surrounds the sliding ring and is attached to the pump housing and / or the connecting housing, and on the other hand, a housing cover which carries the counter ring. According to the invention, the housing cover (together with the counter ring) is detachably attached to the base housing, so that the housing cover together with the counter ring can be separated from and reattached to the base housing. The sealing housing is therefore designed in such a way that the connecting shaft with the sliding ring attached to it (without the counter ring) can be pulled out of the sealing housing. The mechanical seal is preferably a single-acting mechanical seal, i.e.,a single-acting mechanical seal is formed with a single sealing surface between a single sliding ring and a single counter ring. Therefore, within the scope of the invention, a single-acting mechanical seal refers to a mechanical seal with a single sliding ring-counter ring pair.

[0011] The use of such a mechanical seal with a split seal housing allows for the disassembly and consequently the replacement or maintenance of the mechanical seal without further complex disassembly of the pump and, in particular, without disassembling the piping systems or the pump housing. According to the invention, it is possible to first separate the two-part mechanical seal housing through the open or opened connecting housing by detaching the housing cover from the base housing. Subsequently, at least the connecting shaft with the sliding ring arranged on the connecting shaft can be pulled out of the connecting housing in the axial direction (without the counter ring, which is attached to the housing cover). Preferably, access to the pump housing is provided from the stator side. This will be discussed in more detail below. The housing cover (with the counter ring attached to it) can be removed directly from the open or opened connecting housing.by removing the opened connection housing, thus allowing all parts of the mechanical seal to be serviced or replaced, preferably without dismantling the pump housing and the connected piping system and without dismantling the drive.

[0012] The two-part mechanical seal housing according to the invention also offers advantages during subsequent assembly, because the connecting shaft (plug shaft) with the attached sliding ring can be threaded into the mechanical seal housing, namely into the stationary base housing, without the risk of damaging the mating ring, since this mating ring remains detached from the base housing during assembly. Only after the connecting shaft has been inserted (and centered), and preferably only after the connecting shaft has been placed on or inserted into the output shaft of the drive, is the housing cover with the stationary mating ring attached to the base housing, so that there is no risk of damage during the initial threading of the connecting shaft.Overall, the design according to the invention makes it easy and quick to carry out maintenance work on the mechanical seal of the progressive cavity pump, thus enabling particularly economical operation of the pump.

[0013] Particularly advantageously, the design according to the invention allows the rotating unit, or a part thereof, consisting of at least the connecting shaft and preferably also the coupling rod (optionally with joints) arranged between the rotor and the connecting shaft, to be pulled out of the pump housing in a single unit in the axial direction during maintenance work, after the housing cover of the sealing housing has been detached from the base housing. Within the scope of the invention, the term "rotating unit" preferably refers to the unit rotating during operation, which can be completely separated from the drive and consists of at least the connecting shaft, the coupling rod (optionally with joints), and the rotor. However, it is also within the scope of the invention to first separate the rotor from the coupling rod and then to pull the remaining part of the rotating unit (connecting shaft and coupling rod) out of the suction housing as a whole in the manner described.It is not necessary to disassemble the suction housing or the suction line. Preferably, the rotating unit (with sliding ring) or the part of the rotating unit arranged in the suction housing (e.g., without rotor) can be pulled out axially through the housing opening of the pump housing facing the stator.

[0014] To this end, it is advisable to create sufficient space on the stator side of the suction housing for the described disassembly. This can be achieved, for example, by completely removing the stator connected to the suction housing, so that the rotating unit or the described part of the rotating unit can then be pulled out of the pump housing.

[0015] This is preferably achieved in embodiments where the pump stator can be removed without having to remove the drive, suction housing, and suction line. In this case, the discharge line or discharge port may need to be removed to dismantle the stator, after which the described maintenance of the mechanical seal can be carried out via the suction housing as described. This option is also attractive if some disassembly work is required in the area of ​​the discharge housing or discharge lines, for example, if disassembling the suction line (e.g., the hopper in hopper pumps) or the drive would be much more complex than disassembling the discharge line.

[0016] The invention is particularly advantageous in embodiments where the pump stator can be removed without having to remove the drive, the pressure line, the suction line, or the suction housing. Various practical solutions for this are known. With such solutions, the mechanical seal can be serviced or replaced as described without having to dismantle any part of the piping system. The invention is particularly advantageous in such embodiments.

[0017] The invention is particularly preferred in an eccentric screw pump with a longitudinally split stator, which consists, for example, of several (elastic) stator segments, e.g., stator half-shells and / or several shell segments (as a stator clamping device). In such an embodiment, it is particularly easy to simply remove or partially remove only the stator, thus providing access to the rotating unit via the stator-side opening of the pump housing (suction housing). After separating the sealing housing, the rotating unit can then be completely removed. In principle, it is possible to completely remove the entire rotating unit, including the rotor. However, in a preferred embodiment, the rotor is first separated from the rotating unit.the remaining part of the rotating unit, so that the remaining part of the rotating unit (connecting shaft and coupling rod, optionally with joints) can then be pulled out of the pump housing as a single unit. This is achieved, for example, by separating the rotor-side coupling joint and thus removing the rotor from the coupling rod. The invention is particularly advantageous for use in progressive cavity pumps with rotor separation (e.g., according to EP 2 428 680 B1). In this case, the rotor is detachably connected to the rotor-side coupling joint without disassembling the joint, by providing a separation point separate from the joint. Consequently, the rotor can be separated from the rotating unit without separating the joint, and the remaining rotating unit consists of the connecting shaft with the coupling rod, including both joints and the so-called rotor head, which is separable from the rotor. This is illustrated in the description of the figures.

[0018] Furthermore, the invention also offers advantages for pumps where the assembly or disassembly of the suction line of the suction housing is very complex, e.g., for hopper pumps, which may be mounted under silos. In hopper pumps, the inlet and outlet openings are formed by a hopper, and additional conveying devices may be arranged in the suction housing, e.g., on the coupling rod.

[0019] While mechanical seals with a split housing are known in practice, they are only available in the form of double-acting or multi-acting mechanical seals, particularly those implemented as so-called "back-to-back" solutions. These seals feature a sliding ring and a corresponding mating ring at each end of a single housing. Such double-acting mechanical seals require the housing to be opened via a removable cover simply for the purpose of sealing. The concept according to the invention, which allows for easy replacement of the seal without disassembling the housing, cannot be implemented with such double-acting mechanical seals with a removable housing cover. Therefore, the invention preferably relates to single-acting mechanical seals.

[0020] The base housing of the (single-acting) mechanical seal according to the invention is preferably hollow cylindrical. The housing cover is also preferably hollow cylindrical or annular, so that it has a central opening through which the connecting shaft can pass. The mating ring is fixed to the housing cover in a rotationally fixed manner, preferably by being inserted into the mating ring with an interposed seal. The housing cover is preferably detachably fastened to the base housing by means of (positive-locking and / or force-locking) fasteners. These may be, for example, screws and / or locking devices and / or clamping devices.

[0021] The drive of an eccentric screw pump typically has an output shaft, to the pump-side output end of which the connecting shaft is detachably attached with its drive-side shaft end. The drive's output shaft therefore projects into the connecting housing, so that the connecting shaft is coupled to the drive's output shaft within the connecting housing. In the mechanical seal according to the invention with a two-part housing, a preferred embodiment provides that the output end (of the output shaft) is spaced from the base housing of the mechanical seal (in the assembled state) such that the housing cover of the mechanical seal housing can be removed from the connecting housing between the output end (of the output shaft) and the base housing when the connecting shaft is disassembled. This can be, for example,This is achieved by the housing cover, preferably including the attached counter ring, having a length or overall length L in the axial direction that is less than the axial distance A between the output end of the drive shaft and the base housing of the mechanical seal. Consequently, after the connecting shaft has been pulled out of the connecting housing, the housing cover with the attached counter ring can be guided between the stationary base housing and the output shaft and removed from the connecting housing, e.g., for replacement purposes. However, the invention also encompasses alternative embodiments in which the described axial distance A is less than the described overall length L.It is also possible to separate the counter ring of the mechanical seal from the housing cover before radially removing it from the connecting housing, so that it can be removed separately from the connecting housing without the housing cover and then replaced.

[0022] Furthermore, the invention relates to a method for the maintenance (or inspection) and / or replacement of a mechanical seal of a progressive cavity pump of the type described. In this method, the housing cover is first detached from the base housing (for disassembly) through the (end-facing) open or opened connecting housing. Subsequently, at least the connecting shaft with the sliding ring arranged on the connecting shaft is removed axially from the connecting housing and, more preferably, through the end-facing opening of the pump housing. In a preferred embodiment, the already described rotating unit of the progressive cavity pump (including the connecting shaft), optionally after prior separation of the rotor, is removed axially through the pump housing, e.g., after the stator has been removed, for example, in the case of a pump with a longitudinally split stator.The method according to the invention also relates to the assembly of the connecting shaft or the rotating unit (e.g., after replacing the sliding ring and / or the mating ring). For this purpose, the connecting shaft or the rotating unit is first inserted (through the end-face opening) into the connecting housing, with the connecting shaft being pushed through the base housing and the detached housing cover, and then, for example, placed onto or inserted into the output shaft of the drive. Only then is the housing cover attached to the base housing. This procedure has the particular advantage that damage to the sliding ring seal or the mating ring on the housing cover is avoided, since the latter is not permanently mounted but (temporarily) loosely arranged in the connecting housing.

[0023] Optionally, the invention proposes removing the rotating unit from the pump housing during disassembly using an assembly tool (specifically designed for this purpose) and / or inserting it into the pump housing during assembly. Such an assembly tool has at least a plate-shaped or cup-shaped receptacle for the rotating unit and a handle attached thereto. Details are described by way of example in the description of the figures.

[0024] The invention will now be explained in more detail with reference to drawings illustrating only one embodiment. These show: Fig. 1 shows a simplified side view of an eccentric screw pump, Fig. 2 shows an enlarged section of the object. Fig. 1 (in assembled state), Fig. 3 the object according to Fig. 2 during disassembly, Fig. 4 the object according to Fig. 3 in another functional position during disassembly and Fig. 5 an assembly tool for an eccentric screw pump according to the invention or for carrying out a method according to the invention (in a perspective view).

[0025] In Fig. 1 The diagram shows a simplified representation of a progressive cavity pump, which in its basic structure comprises a stator 1, a rotor 2 rotating within the stator 1, and a drive 3 for the rotor 2. For example, a pump housing 4, referred to as the suction housing 4, is connected to the stator 1 on the suction side. A housing part connected to the stator 1 on the pressure side is referred to, for example, as the connection port or pressure port 5. The pump housing 4 has an inlet opening (or, depending on the operating direction, an outlet opening) 6, through which, for example, the medium to be pumped is supplied. This medium is then conveyed from the pump housing 4 via the stator / rotor to the pressure port 5. For this purpose, the pump housing 4 has a (front-facing) opening 7 on the stator side, through which the medium enters the stator 1 from the pump housing 4. The drive 3 is equipped with an output shaft 8, which is connected to a connecting shaft 9.In this embodiment, the connecting shaft 9 is designed as a plug-in shaft. The rotor 2 is connected to the connecting shaft 9 via a coupling rod 10. The coupling rod 10 is connected to the connecting shaft 9 via a drive-side joint 11 and to the rotor 2 via a rotor-side joint 12. The coupling rod 10 and the joints 11 and 12 enable the eccentric movement of the rotor 2 and its rotor end, respectively. However, it is also possible to use embodiments without joints or coupling rods, for example, by making the coupling rod or the rotor-side end (as a coupling rod) elastic. Such an embodiment is not shown. A connecting housing 14, also referred to as a lantern, is arranged between the pump housing 4 and the drive 3.

[0026] This connecting housing 14 is designed to be open, in the exemplary embodiment open at the sides, i.e., it has lateral openings. However, it is also possible for these (lateral, upper, and / or lower) openings to be closable, so that the connecting housing can also be designed as a closed, but openable, housing. For liquid-tight separation of the pump housing 4 from the environment or from the drive, the connecting shaft 9 is sealed with a shaft seal designed as a mechanical seal 13, specifically as a single-acting mechanical seal 13. This mechanical seal 13, which is of particular importance according to the invention, will be described in more detail below. In any case, in the illustrated exemplary embodiment, the coupling rod 10 is arranged (essentially) inside the pump housing 4, while the connecting shaft 9 is arranged (essentially) inside the connecting housing 14.The mechanical seal 13 is also (essentially) located inside the connecting housing 14.

[0027] In the Fig. 1 In the illustrated embodiment, the stator 1 is designed as a longitudinally split stator and, in this embodiment, consists of two stator half-shells 1a, 1b, which are only indicated. Longitudinally split means along or parallel to the longitudinal axis of the stator. The stator is at least partially surrounded by a stator shell 15, which in this embodiment is designed as a longitudinally split shell and has several shell segments 16 that serve as clamping segments and form a stator clamping device. Details of this are not shown; they are known, for example, from DE 10 2014 112 550 B4 or WO 2009 / 024279 A1. However, the invention can also be implemented with other stator designs.

[0028] Furthermore, it can be seen in the figures that an exemplary embodiment with rotor separation (according to EP 2 428 680 B1) is implemented. The rotor 2 can be separated from the coupling rod 10 without disassembling the joint 12, because an additional separation point is provided by the rotor head 17 shown in the figures. The rotor 2 is therefore detachably connected to the rotor head 17, which in turn is connected to the coupling joint 12, without disassembling the coupling joint 12. Fig. 2 bis 4 The figures now show a functional position in which the rotor 2 has already been separated from the rotor head 17 and thus from the remaining part of the rotating unit.

[0029] The mechanical seal 13 has a sealing housing 18 which is attached to the pump housing 4 and / or the connecting housing 14, for example, by being clamped between these two housings 4 and 14 during the fastening of the pump housing 4 to the connecting housing 14, and projecting into the interior of the connecting housing 14. Furthermore, the mechanical seal 13 has a sliding ring 19 which is fixed to the shaft 9 and rotates within the sealing housing 18, as well as a stationary counter ring 20 which is attached to the sealing housing 18. The sliding ring 19 is pressed against the counter ring 20 by a spring element 21, adjustable via an adjusting ring 22. The sliding ring 19, spring element 21, and adjusting ring 22 are generally arranged on a support sleeve 23, which is... B. designed as a rubber sleeve and fitted onto the connecting shaft 9 in a force-fit, rotationally fixed manner.During operation, the sliding ring 19, which is non-rotatably connected to the connecting shaft 9, rotates relative to the stationary counter ring 20, with sealing surfaces 19a, 20a facing each other face to face, which are oriented essentially perpendicular to the axis of rotation R.

[0030] According to the invention, the sealing housing 18 is designed as an (axially) split sealing housing. It comprises, on the one hand, a base housing 18a which surrounds the sliding ring 19 in the assembled state, and on the other hand, a housing cover 18b which supports the counter ring 20. The base housing 18a is permanently attached to the connecting housing 14 and / or pump housing 4 and, in the exemplary embodiment, has an externally circumferential collar 24 which is fixed between the pump housing 4 and the connecting housing 14. The housing cover 18b is detachably attached to the base housing 18a, e.g., by means of screws or other fasteners, so that the housing cover 18b, together with the counter ring 20 attached to it, can be separated from the base housing 18a. The base housing 18a is essentially hollow cylindrical. The housing cover 18b is annular and therefore has a central opening through which the connecting shaft 9 can pass.

[0031] The design according to the invention enables easy maintenance, replacement, and reassembly of a mechanical seal. This is achieved through a comparative analysis of the Fig. 2 , 3 and 4 referred. Fig. 2 Figure 1 shows the eccentric screw pump in its assembled state, but with the rotor already separated. To replace or otherwise service the mechanical seal 13 or parts of the sliding mechanism, the mechanical seal 13 must be removed from the connecting housing or pump housing. For this purpose, the seal housing 18 according to the invention is first disassembled as follows: Fig. 3 The housing cover 18b is removed from the base housing 18a, thereby also separating the counter ring 20 from the sliding ring 19, since the counter ring 20 is rotationally fixed to the housing cover 18b, e.g., pressed into the housing cover 18b with an interposed sealing ring 25. Subsequently, it is possible to remove the housing cover 18b. Fig. 4 As shown, the connecting shaft 9 is pulled axially away from the output shaft 8 and out of the connecting housing 14 (after, of course, the connection between connecting shaft 9 and output shaft 8 has been loosened). In doing so, Fig. 4 It is evident that the connecting shaft 9 also removes the part of the mechanical seal 13, including the sliding ring 19, which is fixed to the connecting shaft 9 against rotation. Interestingly, the connecting shaft 9, with the sliding ring 19 attached to it, can be removed from the connecting housing 14 without having to dismantle the pump housing 4 beforehand. Even the suction line 26, connected to the opening 6, does not need to be removed.

[0032] Furthermore, in Fig. 4 The illustration shows that not only is the connecting shaft 9 removed in the axial direction, but also the rotating unit, or the part of the rotating unit without the rotor, which includes at least the connecting shaft 9 and, in the exemplary embodiment, additionally the coupling rod 10 with the mounted joints 11, 12. This rotating unit can be pulled out of the pump housing 4 in the axial direction via the end-face opening 7, so that the part of the mechanical seal attached to the connecting shaft 9, including the sliding ring 19, is then freely available for maintenance purposes. In the illustrated embodiment, this is particularly easy because the stator 1 can be easily disassembled beforehand, as it is a longitudinally split stator.After disassembly or at least partial disassembly of the stator 1, the rotating unit can be easily pulled out as described, without requiring further disassembly of the pump or its connected components. Crucially, the invention provides access for replacing the mechanical seal via the end-face opening 7 of the pump housing 4. This requires sufficient space for removing the rotating unit. In the exemplary embodiment, this is achieved via the longitudinally split stator. However, the invention also includes embodiments in which the stator can be removed in a different manner. This may require prior disassembly of the pressure-side piping system. In any case, disassembly of the pump housing and suction-side lines is not necessary.

[0033] It is also advantageous that not only the sliding ring 19, but also the counter ring 20 can be easily replaced by removing the housing cover 18b, to which the counter ring 20 is attached, from the connecting housing 14, not via the suction housing, but via the (lateral) openings of the connecting housing 14. For this purpose, the output end 8a of the output shaft 8 is spaced from the base housing 18a of the mechanical seal such that the housing cover 18b can be removed from the connecting housing when the connecting shaft is disassembled between the output end 8a and the base housing 18a. This is achieved by the housing cover 18b, including the counter ring 20 attached to it, having an axial length L that is less than the axial distance A between the output end 8a and the (assembled) base housing 18a.

[0034] The inventive design of the split sealing housing 18 offers advantages not only during the described disassembly but also during the subsequent assembly. It is now possible to first insert the connecting shaft 9, or the entire rotating unit, into the pump housing 4, passing the connecting shaft 9 through the base housing 18a, without the risk of damaging the counter ring 20 located in the housing cover. This is because the connecting shaft 9 is inserted through this housing cover 18b, or the counter ring 20, and placed onto or into the output shaft 8 before the housing cover 18b is attached to the base housing 18a. This means that the housing cover 18b is freely movable within the connecting housing 14 and is only attached to the base housing 18a after the connecting shaft 9 has been inserted.

[0035] In the illustrated embodiment, assembly and disassembly are particularly easy to carry out with an additional assembly tool 27, which is located in Fig. 5 This assembly tool has, on the one hand, a receptacle 28 for the rotating unit and, on the other hand, a handle 29 attached to the receptacle 28. The receptacle 28 can be plate-shaped or shell-shaped and is dimensioned such that it accommodates the rotating unit (here, the connecting rod and shaft) substantially or almost along its entire length, so that the rotating unit, despite its "unstable design" (e.g., with the joints), can be inserted smoothly from the rotor-side end face into the pump housing 4, up to the area of ​​the output shaft 8 of the drive 3. The length of the receptacle 28 of the assembly tool 27 is at least sufficient to accommodate the connecting rod, including the two joints, thus supporting the joints and ensuring a stable arrangement.The length of the mounting tool's receptacle therefore preferably corresponds at least to the length of rotor head 17, joint 12, connecting rod 10 and joint 11. Furthermore, in . Fig. 5 It is evident that the receptacle 28 is designed in a shell-like shape, so that it secures the rotating unit against falling. This shell-like design can, for example, be arcuate in cross-section, preferably circular, so that it has the shape of a (hollow) cylindrical segment. Furthermore, it is evident in Fig. 5It is evident that the flange 30 of the receiving tool, to which the handle 29 and the receiver 28 are connected on one side, has a suitable receptacle or recess, e.g., a groove 31, which in the exemplary embodiment is U-shaped. The rotating unit, namely the rotor head 17, can be inserted (positively) into this receptacle or recess 31, so that the rotating unit is securely held. This receptacle / recess 31 is not only semicircular but preferably U-shaped, so that even higher-profile joint designs (e.g., with boot protection) can be practically accommodated.

Claims

1. A progressive cavity pump having at least - a stator (1), - a rotor (2) rotating inside the stator, - a drive (3) for the rotor, - a pump housing (4) which is connected to the stator (1) and has at least one inlet or outlet opening (6) for the medium to be conveyed, - a connection housing (14), which is arranged between the pump housing (4) and drive (3) and is open or to be opened, - a connecting shaft (9) connected to the drive (3) in a detachable manner, which is arranged in the connection housing (14) at least in some regions, the connecting shaft (9) being sealed using a sliding-ring seal (13) for fluid-tight separation of the pump housing (4) with respect to the environment or with respect to the connection housing (14), the sliding-ring seal (13) having a seal housing (18) fixed to the pump housing (4) and / or the connection housing (14), a sliding ring (19) which is fixed on the connecting shaft (9) in a rotationally fixed manner and rotates in the seal housing (18), and a stationary seal face (20) which is fixed to the seal housing (18), the seal housing (18) being constructed as a divided seal housing and having a basic housing (18a), which in the mounted state surrounds the sliding ring (19) and is fixed to the pump housing (4) and / or the connection housing (14), on the one hand and a housing lid (18b), which supports the stationary seal face (20), on the other hand, characterized in that the housing lid (18b) is fixed to the basic housing (18a) in a detachable manner and can be disconnected from the same, so that the connecting shaft (9) with the sliding ring (19) fixed thereto can be pulled out of the seal housing (18).

2. The progressive cavity pump according to Claim 1, characterized in that the sliding-ring seal (13) is constructed as a single acting sliding-ring seal.

3. The progressive cavity pump according to Claim 1 or 2, characterized in that the basic housing (18a) is constructed to be hollow cylindrical and / or in that the housing lid (18b) is constructed to be hollow cylindrical or annular with a central aperture for the connecting shaft (9).

4. The progressive cavity pump according to one of Claims 1 to 3, the drive (3) having an output shaft (8), at the pump-side output end (8a) of which, the drive-side shaft end of the connecting shaft (9) is fixed in a detachable manner, characterized in that the output end (8a) is spaced from the basic housing (18a) of the sliding-ring seal (13) in such a manner that the housing lid (18b) can be removed from the connection housing (14) in the dismantled state of the connecting shaft (9) between output end (8a) and basic housing (18a).

5. The progressive cavity pump according to Claim 4, characterized in that the housing lid (18b), preferably including the stationary seal face (20) fixed thereto, has a length (L) in the axial direction, which is smaller than the axial spacing (A) between output end (8a) and basic housing (18a).

6. The progressive cavity pump according to one of Claims 1 to 5, characterized in that the stator (1) as a longitudinally split stator consists of a plurality of stator segments and / or in that the stator (1) is surrounded by a stator casing (15), which, preferably as a longitudinally split casing, consists of a plurality of casing segments (16), which preferably form a stator clamping device.

7. A method for maintaining and / or for replacing a sliding-ring seal (13) of a progressive cavity pump according to one of Claims 1 to 6, the progressive cavity pump having at least - a stator (1), - a rotor (2) rotating inside the stator, - a drive (3) for the rotor, - a pump housing (4) which is connected to the stator (1) and has at least one inlet or outlet opening (6) for the medium to be conveyed, - a connection housing (14), which is arranged between the pump housing (4) and drive (3) and is open or to be opened, - a connecting shaft (9) connected to the drive (3) in a detachable manner, which is arranged in the connection housing (14) at least in some regions, the connecting shaft (9) being sealed using a sliding-ring seal (13) for fluid-tight separation of the pump housing (4) with respect to the environment or with respect to the connection housing (14), the sliding-ring seal (13) having a seal housing (18) fixed to the pump housing (4) and / or the connection housing (14), a sliding ring (19) which is fixed on the connecting shaft (9) in a rotationally fixed manner and rotates in the seal housing (18), and a stationary seal face (20) which is fixed to the seal housing (18), characterized in that the seal housing (18) is constructed as a divided seal housing and has a basic housing (18a), which in the mounted state surrounds the sliding ring (19) and is fixed to the pump housing (4) and / or the connection housing (14), on the one hand and a housing lid (18b), which supports the stationary seal face (20), on the other hand, which housing lid is fixed to the basic housing (18a) in a detachable manner and can be disconnected from the same, and in that for disassembly, initially, the open or opened connection housing (14) is detached from the basic housing (18a) through the housing lid (18b) and subsequently at least the connecting shaft (9) with the sliding ring (19) arranged on the connecting shaft (9) is removed from the connection housing (14) in the axial direction and preferably through the pump housing (4).

8. The method according to Claim 7, characterized in that a rotating unit of the progressive cavity pump, which consists of at least the coupling rod (10) and connecting shaft (9), is removed as a whole in the axial direction through the pump housing (4), e.g. through a housing opening (7) facing the stator.

9. The method according to Claim 7 or 8, characterized in that initially the stator (1) is detached and subsequently the rotating unit is removed from the pump housing (4) through a housing opening (7) facing the stator (1).

10. The method according to one of Claims 7 to 9, characterized in that in the course of assembly, the connecting shaft (9) or the rotating unit is initially pushed into the pump housing (4) and in the process, the connecting shaft (9) is plugged through the basic housing (18a) and the housing lid (18b), which is detached therefrom, and e.g. plugged onto the output shaft or into the same and in that the housing lid (18b) is subsequently fixed to the basic housing (18a).

11. The method according to one of Claims 7 to 10, characterized in that the rotating unit is removed from the pump housing during disassembly using an assembly tool (27) and / or introduced into the pump housing (4) during assembly, wherein the assembly tool has at least one mount (28) for the rotating unit and a handle (29) fixed thereto.

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