Pump

Abstract

Pump for a cryogenic liquid in a conveying tube (7) with an electric motor, comprising a motor stator (9) as a part of the conveying tube or around the conveying tube, a rotor (1) inside the conveying tube and the motor stator, comprising a motor rotor (3) and at least one fluid-mechanical conveying element (4) for converting a rotation of the rotor into a fluid flow in the conveying tube and a rotational bearing (2, 8) for the rotor, wherein the motor rotor (3) comprises a squirrel-cage rotor made of a high-temperature superconductor (HTS), and the motor stator (9) is operable with an alternating electromagnetic field.

Description

[0001] The invention relates to a pump for a cryogenic liquid or liquid mixture in a conveying pipe with a motor according to the first patent claim.

[0002] Cryogenic liquids are substances liquefied by cooling, with boiling points particularly below 150 Kelvin. For the purposes of this application, these cryogenic liquids are also limited to substances with a melting point below the transition temperature T c of superconductors. The transition temperature Tc in this application is preferably between 40 K and 110 K (the current upper limit of 110 K is given by the HTS BSCCO; no HTS with a higher transition temperature is known). Important cryogenic liquids include helium (boiling point 4.222 K), hydrogen (boiling point 20.268 K), nitrogen (boiling point 77.35 K), argon (boiling point 87.15 K), or oxygen (boiling point 90.18 K).

[0003] Many conventional pumps for cryogenic liquids in a cryogenic piping system are designed in such a way that a pump body, such as one inside the piping system, is driven by a motor outside the piping system. Centrifugal pumps, for example, are used. These typically use mechanical elements to transmit power, which disadvantageously represent a thermal bridge from the cryogenic piping system and cause heat loss in the cold. This also limits the pump's efficiency.

[0004] US 11242853 B2 discloses, by way of example, a pump for liquid refrigerants having a pump body which is driven by a motor in the pump housing via mechanical transmission means.

[0005] DE 1 653 448 A1 discloses a pump for cryogenic liquids with a piston made of a superconducting material. The piston is arranged in a cylinder, at each end of which is a free volume with an inlet and an outlet valve for the liquids. The piston is moved back and forth by means of an alternating electromagnetic field, whereby the two free volumes cyclically expand and contract, creating a pumping effect via the valves.

[0006] DE 10 2008 011 456 A1 also discloses a freely oscillating piston pump for cryogenic liquids, driven by an electrodynamic linear motor.

[0007] However, unlike centrifugal pumps, piston pumps do not produce constant but pulsating fluid flows.

[0008] Cryogenic pumps are designed to transport cryogenic liquids (or gases) as efficiently as possible and with minimal heat input. Heat loads are particularly caused by - Cold bridges caused by mechanical and / or electrical components from warm to cold (e.g. cables, bushings, shafts, bearings) and - Heat generated by the moving parts in the fluid itself (e.g. flow resistance, friction, ohmic losses / heat, alternating field losses)

[0009] Based on this, one object of the invention is to propose a pump for a cryogenic liquid or liquid mixture which is suitable for generating a constant liquid flow while reducing heat losses.

[0010] The problem is solved with a pump having the features of claim 1. Subclaims referring back to this claim reflect advantageous embodiments.

[0011] To achieve this objective, a pump for a fluid in a delivery pipe with an electric motor is proposed. The pump comprises a motor stator, a rotor, and a rotary bearing for the rotor. It is essential that the motor stator forms part of the delivery pipe or is arranged around the delivery pipe. The rotor comprises a motor rotor and at least one fluid-mechanical conveying element for converting a rotation of the rotor into a fluid flow in the delivery pipe. The rotor is located entirely within the interior of the delivery pipe, and at least the motor rotor is also located within the motor stator. The rotary bearing enables the rotor to rotate, preferably about a rotational axis, and is mounted concentrically to the surrounding, preferably straight, delivery pipe section.

[0012] A key concept lies in the integration of the drive motor in the conveyor pipe, with the stator arranged around the pipe or forming the conveyor pipe wall, and the rotor arranged in the pipe, with at least the motor rotor rotating within the pipe, mounted in the stator's magnetic field, and performing a rotary motion. The rotor, fluid-mechanical conveyor element, and any mechanical elements in between constitute the only mechanically rotating parts, which are arranged entirely within the conveyor pipe. The fluid flow flows around them and, advantageously, are not suitable for forming a cold bridge between the fluid flow and the environment outside the conveyor pipe.

[0013] A key feature of the pump concerns the motor rotor, which comprises a squirrel-cage rotor made of a high-temperature superconductor (HTS), preferably ribbon-shaped HTS RE-123 (REBaCuO), ribbon-shaped HTS Bi-2223, or Bi-2212 (each a compound of BiSrCaCuO). This rotor can preferably be cooled below its critical transition temperature by the cryogenic fluid that surrounds the rotor and the motor rotor. The cryogenic fluid thus ensures zero resistance in the HTS, enabling operation of the HTS, for example, in the so-called Shubnikov phase with non-zero magnetization and loss-free current densities. Heat loads due to ohmic losses are thus drastically reduced. Another key feature is the motor stator, which generates a rotating electromagnetic (alternating) field. It preferably comprises motor stator windings made of copper.A pump equipped with this device comprises a squirrel cage motor which operates particularly effectively and innovatively in synchronous operation (zero slip).

[0014] Squirrel-cage motors have a cage in the motor rotor (rotor) with several struts made of the aforementioned HTS arranged around the rotor circumference. The struts are distributed at equal distances from one another around the rotor circumference and are preferably aligned axially parallel (or at a small angle to avoid cogging torques) to the rotation axis. An optional design provides a cage with two circumferential end rings, which are also preferably made of the aforementioned HTS and which each short-circuit one of the two ends of all struts. The struts and end rings are preferably integral or form a continuous coating.

[0015] A preferred embodiment provides longitudinally slotted struts. The struts preferably have only one central longitudinal slot, which divides the strut into two half-struts, each of which preferably has a consistent and identical cross-section. In the preferred embodiment, the ends of the struts remain unslotted, with the aforementioned end rings preferably being omitted. Each of these struts then forms a superconducting ring conductor; the use of HTS thus renders the motor rotor a synchronously operating squirrel-cage rotor. Power leads to the motor rotor are not required. The width of the slots and the circumferential spacing of the unconnected strut pairs determine the number of poles and the magnetic flux densities across the rotor shell.

[0016] Another basic idea of ​​the solution lies in the thermal division of the pump into a colder cryogenic zone with temperatures below the transition temperature of the HTS used in the rotor and a warmer zone with temperatures above the aforementioned transition temperature, preferably ambient temperature. The colder cryogenic zone comprises the rotor, which is arranged entirely inside the conveyor pipe and surrounded by the cryogenic liquid, and which can then advantageously be operated superconductingly. In the warmer zone, however, the motor stator and the bearing stators are preferably arranged with copper windings to generate magnetic fields acting on the rotor, which can then preferably be operated in the non-superconducting temperature range (advantage: lower cryogenic losses). A particularly advantageous feature here is the absence of fixed contacts such asElectrical sliding contacts, shaft bushings or rolling or sliding bearings through the conveyor pipe wall to the rotor, as possible heat transfer bridges between the two aforementioned areas.

[0017] In contrast to conventional squirrel-cage motors, the proposed designs do not follow the general topology of conventional rotors. In particular, the struts and end rings have no electrical contact and thus, advantageously, no heat transfer elements from the conveyor pipe in the proposed application area. It is indicated that end rings can be dispensed with in the proposed squirrel-cage motors due to the stable magnetization of the synchronous stator field.

[0018] Conventional squirrel-cage motors of the previously proposed designs can only be operated as asynchronous motors; the proposed and claimed motor, in contrast, operates only transiently asynchronously, but then synchronously in the steady state. A motor rotor installed in the conveyor pipe requires neither an electrical connection nor, in the case of contactless bearings (e.g., magnetic bearings or flow bearings), a mechanical connection, but is completely encased in the cryogenic liquid.

[0019] In conventional squirrel cage motors, the mechanical shaft work E mechan is identical to the ohmic heat E dissipated in the squirrel cage rotor ohm = RI 2which is released into the surrounding liquid. The latter, however, only occurs if the aforementioned struts and ring conductors are made of non-superconducting materials. Consequently, the use of motor rotors made of non-superconducting materials is prohibited in cryogenic liquids, such as in the present application as a cryopump, due to the heat generated and absorbed by the liquid. Although the electrical conductivity of metals increases upon cooling, a residual ohmic resistance remains. This is often specified by the RRR value (residual resistance ratio: ratio of room temperature resistance to resistance at T = 4.2 K). RRR values ​​between 100 and 200 are achievable for very pure metals. Associated with the residual electrical resistance R when operating with an electrical current I, is the ohmic heat load E. ohm = RI 2 .

[0020] Furthermore, conventional ferrite magnets (in a conventional, permanent-magnetically excited rotor) permanently (irreversibly) lose part of their magnetization at temperatures below -40°C, making them unsuitable for cryogenic liquids. Alternative neodymium magnets also exhibit a non-linear magnetization curve with decreasing temperature, which also precludes their use. However, at cryogenic temperatures below -138°C, the magnetization is reversibly reduced by approximately 10 to 20% due to a change in the magnetization direction. Furthermore, a deterioration (embrittlement) of the mechanical properties at low temperatures must be taken into account. While the use of permanent magnets in the motor rotor of cryogenic fluid pumps is possible in principle, it significantly reduces their performance at the low temperatures prevailing in cryogenic liquids.

[0021] The motor rotor preferably comprises at least one of the fluid-mechanical conveying elements and / or connecting means between the motor rotor and the at least one fluid-mechanical conveying element. The connecting means form a preferably rigid coupling between the motor rotor and the conveying elements in the pump.

[0022] Within the scope of the invention, the cryogenic liquid is preferably a liquid or liquid mixture whose boiling point is below the critical transition temperature of the HTS of the struts and the end rings. During use of the pump to convey these, the cryogenic liquid is in a liquid state in the conveyor pipe, i.e., together with the motor rotor, it is in a temperature range below the critical transition temperature. Advantageously, the superconducting properties of the motor rotor are ensured by the cryogenic fluid flow, and at the same time, no cold bridge is created apart from the conveyor pipe wall. Preferably, the motor stator can be operated with an alternating electromagnetic field, wherein the alternating field frequency, together with the number of slots and poles, determines the speed of the motor rotor.

[0023] The bearings of the rotor are preferably passive magnetic bearings as rotational bearings, each with a bearing rotor made of a superconducting material in a preferably stationary magnetic field of a bearing stator.

[0024] The motor rotor is mounted with the rotor in the conveyor pipe, i.e. its mobility is guided by a rotary bearing. The rotary bearing preferably has one or more passive magnetic bearings. In these, a rotating bearing rotor made of a superconducting material is preferably mounted as a component of the rotor in a contactless manner in a magnetic field of a bearing stator with permanent and / or electromagnets in or around the conveyor pipe. The bearing rotors are advantageously arranged completely in the liquid flow and are temperature-controlled by it. The use of magnetic bearings avoids or reduces mechanical contact with components that are connected to the conveyor pipe or other areas that are warmer than the temperature of the cryogenic liquid. This also reduces the heat input into the rotor through thermal conduction.

[0025] A preferred embodiment provides a rotation bearing for the rotation of the rotor only about a rotation axis concentric to the conveyor pipe.

[0026] Using HTS magnets for the cold part, i.e., the bearing rotor, avoids the degradation of conventional permanent magnets and benefits from the higher magnetization potential of HTS. The warmer part of the magnetic bearing comprises the bearing stator, where the magnets are preferably located outside the conveyor pipe and, in this position, can preferably be implemented with conventional magnets and / or electromagnetic coils.

[0027] The pump with the aforementioned features is an axial pump with a rotating rotor that conveys the fluid flow in the delivery pipe at least predominantly, preferably entirely, axially, i.e., parallel to the axis of rotation. Particularly when the axis of rotation is concentric with the delivery pipe, axial conveying advantageously eliminates the need for flow deflection, which would only result in an additional heat load in the cryogenic liquid being conveyed due to additional flow resistance.

[0028] In one embodiment, the motor rotor comprises at least one of the fluid-mechanical conveying elements. These are preferably incorporated into the motor rotor as threads, or mounted thereon as blades, or inserted into the rotor as impellers. Additionally or alternatively, connecting means are provided between the motor rotor and the at least one fluid-mechanical conveying element. The connecting means preferably comprise the aforementioned rotor shaft, which serves as a support for the motor rotor and the at least one conveying element arranged axially in front of or behind it.

[0029] Preferably, the motor stator comprises motor stator windings made of copper.

[0030] In summary, the proposed solution has the following properties, features and advantages: - Avoid a mechanical wave or other mechanical transmission means from hot to cold - Avoid electrical current supply from hot to cold - Use of high-temperature superconductors (HTS) as (synchronously operating) squirrel cage rotors in cold - Using a stator on the outside of the line around the rotor - Preferably a magnetic bearing of the rotor in the line - Preferably a superconducting magnetic bearing of the rotor

[0031] A temperature of the cryogenic liquid below the critical temperature of the HTS is necessary (e.g. in the case of liquid hydrogen 21 K compared to the HTS RE-123 with 92 K).

[0032] The invention and its mode of operation are explained in more detail with reference to the following exemplary embodiments, the following figures, and descriptions. They contain rotors according to the four basic forms described below. All features and their combinations are not limited to these exemplary embodiments. Rather, they should be considered representative of other possible configurations that are not explicitly shown as exemplary embodiments. Fig. 1a and b are schematic sectional views of an embodiment of a pump with the delivery pipe, rotor according to a first basic form of the rotor as well as bearing and motor stator, Fig. 2 shows an exemplary rotor according to a further embodiment of the first basic form, Fig. 3a and b show exemplary rotors according to a second basic form, Fig. 4 shows an exemplary tubular rotor according to a third basic form, Fig. 5 shows an exemplary rotor according to a fourth basic form and Fig. 6a to c show various designs of the motor rotor in detail in the preferred squirrel cage design.

[0033] The proposed pump includes in the Fig. 1a and Fig. 1b, a rotor 1 comprising two bearing rotors 2, a motor rotor 3 and two fluid-mechanical conveying elements 4 on a rotor shaft 5. The rotor is inserted axially into a conveying pipe 7 so as to be rotatable about a rotation axis 6 and is guided by a bearing stator 8. A motor stator 9 serves to generate a circulating magnetic field in which the motor rotor is positioned and driven in rotation. In the exemplary embodiments shown, the two fluid-mechanical conveying elements 4 are each mounted on the ends of the rotor shaft as flow screws, with the generated flow being guided through axial recesses 10 or openings 11 through the bearing rotors and the motor rotor, indicated by dashed lines. Further design options for the fluid-mechanical conveying elements are described below using four basic rotor shapes.

[0034] The motor rotor is completely surrounded by the cryogenic liquid inside the conveyor tube and has neither a power supply, e.g., electrical sliding contacts, nor any other mechanical transition as a thermal bridge from the interior of the conveyor tube. Preferably, the rotor absorbs the temperature of the surrounding cryogenic liquid, while heat exchange with significantly warmer regions in or around the conveyor tube does not occur via solid-state contact. This advantageously improves the thermal separation of a colder region, comprising the rotor with the cryogenic liquid, from an adjacent warmer region, comprising the motor and bearing stators operable in non-cryogenic temperature ranges.

[0035] The conveyor pipe itself is preferably made of a material with low conductivity, preferably a plastic or a composite material with at least one plastic layer.

[0036] Bearing stators 8 and motor stator 9 are either mounted on the outside of the conveyor pipe ( Fig. 1a) or inserted and forming the inner wall of the conveyor pipe ( Fig. 1b).

[0037] Preferably, in all embodiments, it is proposed to additionally cover the inner wall of the conveyor pipe with a thermal insulation layer (in Fig. 1a and b not shown), whereby undesirable heat transfer between the cryogenic liquid in the interior (colder area) to the motor stator and the bearing stator (warmer area) is advantageously further reduced.

[0038] Not further not in Fig. 1a and b show optional designs in which only the motor stator or only the bearing stators are inserted into the conveyor tube and form the inner wall of the conveyor tube, while the remaining stators are placed on the conveyor tube.

[0039] Also not in Fig. 1a and b show rotors with optionally different basic shapes or further embodiments, which are explained in more detail below.

[0040] The motor rotor is mounted in the conveyor pipe via a rotary bearing with a bearing stator and bearing rotor, which interact magnetically with each other and guide the rotor not only radially but also axially within the conveyor pipe. Instead of a magnetic rotary bearing, a gap flow bearing is also proposed as an option or as a supplement.

[0041] The following embodiments, representing four basic shapes, are proposed for the rotor. They can be combined with each other, but only in terms of features and configurations: 1. Fig. 1a and b, as well as 2, represent the first basic shape in the form of a first embodiment. It comprises a rotor shaft 5, which is arranged inside a preferably straight section of the conveyor pipe 7, more preferably concentrically within this section. The rotor 1 is preferably supported by the rotor shaft 5, more preferably by means of two bearings (motor stator 9 and bearing rotor 2) on either side of the motor rotor 3 in the conveyor pipe. Within the scope of a first preferred embodiment, at least one fluid-mechanical conveying element 4 for converting a rotation of the rotor shaft 5 into a fluid flow is mounted axially in the section on the rotor shaft. The fluid-mechanical conveying means 4 are preferably, as shown, a propeller or conveying screws (see FIG. Fig. 1a and b). A second preferred embodiment of the rotor shaft shows Fig. 2. It provides a tube 12 open on both sides as the rotor shaft 5, supporting the motor rotor 3 and the bearing rotors 4. The fluid-mechanical conveying elements 4 preferably comprise at least one impeller 13 in the tube, either as the sole conveying element or—as shown—in addition to a conveying element such as a propeller 14 on the rotor shaft. The rotor shaft serves as a connecting means between the motor rotor and the at least one fluid-mechanical conveying element, preferably all conveying elements. 2. The second basic form, represented by Fig. 3a and b in the example of a second embodiment, sees a motor rotor 3 with at least one incorporated conveying element 16 (cf. Fig. 3a) or attached conveyor element (cf. Fig. 3b), which is preferably arranged evenly around the motor rotor. These conveying elements are supported by annular impeller inserts 15 in axial openings in the two bearing rotors 2. Preferably, the aforementioned impeller inserts also serve as supports for a bearing rotor mounted annularly on them. The fluid flow flows around the motor rotor in a bypass flow. A preferred embodiment according to Fig. 3a provides continuous helical grooves 16 as a fluid-mechanical conveying element in the motor rotor, ie, incorporated into the outer surface of the motor rotor 3. The conveying elements and motor rotor are preferably a single component, ie, the conveying elements are integral parts of the motor rotor. An alternative preferred embodiment according to Fig. 3b preferably provides helical flow guide elements 17 mounted on the outer surface of the motor rotor 3. The motor rotor is preferably mounted in the conveyor pipe via a separately provided rotor shaft 5 as described. 3. The third basic form, represented by Fig. 4 in the example of a third embodiment without a motor shaft, shows a preferably tubular motor rotor 3 with integrated bearing rotor 2 and, in the example shown, helical grooves 16 incorporated therein as well as impellers 13 inserted into an (optional) central axial inner bore 18 as fluid-mechanical conveying elements 4. The motor rotor extends axially both over the motor stator 9 and over the two bearing stators 8. 4. The fourth basic form, represented by Fig. 5, in the example of a fourth embodiment, provides a necessarily tubular motor rotor 3 with tubular bearing rotors 2 attached on both sides, which together form a rotor tube 19. A rotor shaft is not provided and is not required here. At least one impeller 13 is inserted into the rotor tube as the sole fluid-mechanical element 4.

[0042] Fig. 6a to c show various embodiments of the motor rotor in detail in the preferred squirrel cage design with a superconducting cage 20 preferably made of an HTS on a preferably metallic base body 21. The cage is applied as an HTS layer to the preferably iron-containing base body.

[0043] Fig. 6a and b represent a first embodiment of the cage 20 with struts 22 on the circumference of the tube, which terminate on both sides in an end ring 23 and together with these form a common HTS layer on the base body. The coating processes proposed for this purpose are, in particular, IBAD (Ion Beam Assisted Deposition = ion beam-assisted deposition, e.g., for buffer layers) or PLD (Pulsed Laser Deposition = laser beam evaporation), alternatively, e.g., CVD (Chemical Vapor Deposition = chemical vapor deposition). Fig. 6a are in Fig. 6b the struts are not applied in a straight line, but in a curved manner, with the areas between the struts preferably being used for attached helical flow guide elements (cf. Fig. 3b Pos. 17) and / or incorporated helical grooves (cf. Fig. 3a, item 16) is available as at least part of the fluid-mechanical conveying elements. A preferred embodiment provides for an alternating sequence of the aforementioned flow guide elements and grooves.

[0044] Fig.6c, on the other hand, shows the aforementioned alternative embodiment of the cage 20, applied as an HTS layer to the metallic base body 21. The cage comprises axial struts 22 without end rings, arranged circumferentially at equal distances from one another (or with a small tilt angle of a maximum of 30°, preferably a maximum of 15°, more preferably a maximum of 10° or 5° to the rotation axis), each of which is separately divided by a longitudinal slot 24 into two partial struts, except for the two end regions 25, thus each forming a superconducting ring conductor. A further embodiment of this embodiment (not shown in detail) provides for a helical arrangement of the struts over the circumference of the base body instead of an axial arrangement, wherein the intermediate spaces can be used for fluid-mechanical conveying elements as described above. List of reference symbols: 1 rotor 2 bearing rotor 3 Motor rotor 4 fluid-mechanical conveying element 5 Rotor shaft 6 Rotation axis 7 Conveyor pipe 8 Bearing stator 9 Motor stator 10 axial recess 11 Breakthrough 12 pipe 13 impellers 14 propellers 15 Annular impeller insert 16 helical grooves 17 Helical flow guide elements 18 inner bore 19 Rotor tube 20 cages 21 basic body 22 Strut 23 End ring 24 Longitudinal slot (in a strut 22) 25 End area (of a slotted strut 22) QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] US 11242853 B2

[0004] DE 1 653 448 A1

[0005] DE 10 2008 011 456 A1

[0006]

Claims

[1] Pump for a cryogenic liquid inside a conveyor pipe (7) with an electric motor, comprising a) a motor stator (9) arranged without direct contact with the interior of the conveyor pipe either as part of the conveyor pipe or around the conveyor pipe, b) a rotor (1) inside the conveyor pipe and the motor stator, comprising a motor rotor (3) and at least one fluid-mechanical conveying element (4) for converting a rotation of the rotor into a fluid flow in the conveyor pipe and c) a rotary bearing (2, 8) for the rotor, characterized by , that d) the motor rotor (3) is a squirrel cage rotor made of a high-temperature superconductor with a transition temperature T c greater than 40K, e) the motor rotor is arranged without a power supply and without contact inside the conveyor pipe, and f) the motor stator (9) can be operated with an alternating electromagnetic field. [2] Pump according to claim 1, characterized by that the rotation bearing (2, 8) is one or more passive magnetic bearings, each with a bearing rotor (2) made of a superconducting material in a magnetic field of a bearing stator (8) with permanent magnets in or around the conveyor pipe (7). [3] Pump according to claim 1 or 2, characterized by that the rotation bearing (2, 8) is only suitable for the rotation of the rotor (1) about a rotation axis (6) concentric to the conveyor pipe (7). [4] Pump according to one of the preceding claims, characterized by that the motor rotor (1) comprises at least one of the fluid-mechanical conveying elements (4) and / or connecting means are provided between the motor rotor (3) and the at least one fluid-mechanical conveying element. [5] Pump according to one of the preceding claims, characterized bythat the rotor (1) has a rotor shaft (5), wherein the rotation bearing (2, 8) has two bearings of the rotor shaft on both sides of the motor rotor (3) in the conveyor pipe (7). [6] Pump according to claim 5, characterized by that the at least one fluid-mechanical conveying element (4) and the rotor are fastened to the rotor shaft (5). [7] Pump according to claim 5 or 6, characterized by that the at least one conveying element (4) comprises at least one propeller (14) coupled to the rotor shaft with a propeller axis concentric with the rotor shaft (5). [8] Pump according to one of claims 5 to 7, characterized by that the rotor shaft (5) comprises a tube (12) open on both sides and the propeller comprises an impeller (13) in a tube. [9] Pump according to one of the preceding claims, characterized by that the motor stator (9) comprises motor stator windings made of copper. [10] Pump according to one of the preceding claims, characterized bythat the liquid is a cryogenic liquid or liquid mixture whose boiling temperature is below the critical transition temperature of the high-temperature superconductor. [11] Pump according to one of the preceding claims, characterized by that the at least one conveying element (4) comprises continuous helical grooves (16) in the motor rotor arranged uniformly around the motor rotor (3). [12] Pump according to one of the preceding claims, characterized by that the rotor (1) is tubular, does not comprise a rotor shaft, the motor rotor and the bearing rotors (3) are in one piece and at least one of the conveying elements (4) is enclosed as an impeller (13) in the tubular rotor. [13] Pump according to one of the preceding claims, characterized by that the squirrel cage rotor has struts made of high-temperature superconductor oriented parallel to the rotation bearings around the circumference of the motor rotor. [14] Pump according to claim 13, characterized bythat the struts are connected at each end and in pairs to form ring conductors. [15] Pump according to claim 13, characterized by that the struts are electrically connected to each other at each end by an end ring. [16] Pump according to claim 15, characterized by that the end rings and struts are formed by a continuous coating on the circumference of the motor rotor. [17] Pump according to one of the preceding claims, characterized by that the conveyor pipe has a separate thermal insulation layer on the inner wall.

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