Centrifugal pump with slit tube motor

Abstract

The invention relates to a centrifugal pump with an impeller (2), which is arranged in a housing (1). The impeller (2) is driven by a slit tube motor. The slit tube motor has a device (3) for the connection with the housing (1), and the device (3) comprises a connection piece (15), which is integrally configured with an element (8) for separating a rotor (6) from a stator (5) of the slit tube motor. The device (3) has a bearing assembly (14), which is integrally formed into the device (3) in a form-locking and / or material-locking manner.

Description

Technical Field

[0001] The present invention relates to a centrifugal pump having an impeller arranged in a housing and driven by a spaltrohr motor, wherein the spaltrohr motor has means for connection to the housing, and the means includes a connector integrally constructed with an element for separating the rotor and stator of the spaltrohr motor. Background Technology

[0002] Centrifugal pumps with slotted tube motors are characterized by their integral and compact construction. These pumps have a helical casing within which a bladed impeller rotates at high speeds. This impeller is driven by an electric motor via a pump shaft. The stationary stator and rotating rotor of the electric motor are sealed apart by a tubular inner casing. This so-called slotted tube (Spaltrohr) can be made of non-magnetized chromium-nickel steel or composite materials. The enclosed rotor runs in the conveying fluid to dissipate heat loss. Simultaneously, the conveying fluid lubricates two hydraulically driven sliding bearings in the rotor chamber. The surrounding magnetic field in the stator windings induces a magnetic field in the rotor windings, thereby putting the rotor into motion. In addition to the slotted tube acting as a tightly sealed component, the motor housing serves as a second safety shield. Centrifugal pumps with slotted tube motors are distinguished from conventional centrifugal pumps and magnetically coupled pumps not only by their short and compact construction but also by their very low noise levels.

[0003] Centrifugal pumps with slotted tube motors are used in various applications where hot, corrosive, explosive, or toxic liquids must be pumped, and therefore, high priority must be given to enclosed units without stoppered tanks or slip ring seals. This is true in heating circulating pumps and reactor circulating pumps, as well as in process pumps used in chemical and technological processes.

[0004] The design of slot tubes is often a key focus of research and development. On one hand, the material of the slot tube should be non-conductive to avoid eddy current losses. On the other hand, the slot tube should be implemented to be as thin as possible, yet also pressure-stable.

[0005] DE 10 2005 009 260 A1 describes a slit tube for a centrifugal pump, which is open at both ends and has a bearing cap formed on the pump side within the slit tube. The goal of this one-piece design is to reduce the number of parts and installation costs. A particularly disadvantageous aspect of this configuration is that the pump-side bearing must be introduced through the open and very narrow ends of the slit tube and fitted into the bearing housing along with a filter element. A difficulty in installation lies in the need to install a reinforcing tube around the slit tube to withstand pressure loads.

[0006] EP 22 93417 B1 describes a slotted tube for a wet rotor electric motor, the slotted tube being made of a thermoplastic material and the bearing housing being surrounded by a thermoplastic material on the motor side. Here, the number of components and installation costs should also be reduced. To make the slotted tube sufficiently pressure-resistant, a fiber-reinforced thermoplastic tape layer is applied during a very complex winding process. The more pressure-resistant the slotted tube must be designed, the more complex the winding process becomes. Summary of the Invention

[0007] The objective of this invention is to provide a device comprising connectors and separation components, and a method for manufacturing the device. The device should consist of as few parts as possible, thereby simplifying the installation of the slit-tube motor of the centrifugal pump. The device should be constructed of non-conductive materials and be extremely thin. Furthermore, the device should be designed to be pressure-stable and chemically resistant. The device should be readily and cost-effectively implemented.

[0008] According to the present invention, this task is accomplished by the apparatus and manufacturing method described in the independent claim. Preferred variations can be learned from the dependent claims, the specification, and the drawings.

[0009] According to the invention, the pump-side bearing assembly is shape-locked and / or material-locked to the device. Advantageously, the sliding bearing is placed in a die-casting mold and cast with a synthetic material, thereby producing an integrated device with an integrated bearing. The integrated device is particularly installation-friendly because it combines multiple components that previously had to be installed individually and at great expense into one device. Similarly, installation errors that occur when pressing the bearing into the bearing housing are avoided. Due to the integrated construction of the invention, the seal, along with its associated sealing surface, can be omitted.

[0010] According to the invention, the device is manufactured by molding. For this purpose, the device is cast from synthetic materials, preferably high-performance synthetic materials. High-performance synthetic materials are a group of thermoplastic synthetic materials, characterized in that they possess both improved mechanical properties and temperature and chemical resistance. Furthermore, they are non-conductive, thereby avoiding eddy current losses during the operation of the slotted tube motor. Examples of such materials include polyetherketone, polyetheretherketone, polyphenylene sulfide, and polyamide. Unlike devices made of brass, devices made of high-performance synthetic materials can be produced to be thinner.

[0011] Fortunately, the device takes over the task of the slot tube, which is also constructed as an integral component with a connector designed as a so-called pressure cap.

[0012] In a particularly advantageous variant of the invention, the reinforcing elements typically required to improve the rigidity and compressive strength of the device are incorporated into the injection mold and cast using a high-performance synthetic material, resulting in a monolithic device having formed connectors, tubular elements for separation, cast bearings, and cast reinforcing elements. This again eliminates additional installation steps. In this variant, the reinforcing elements, designed as reinforcing tubes made of carbon fiber or as wound sections made of carbon fiber-reinforced synthetic material strips, can be constructed particularly thin, resulting in a composite of the high-performance synthetic material and the wound section with a wall thickness of less than 2 mm, preferably less than 1.5 mm, and particularly less than 1 mm.

[0013] In another variation, the bearing assembly can also be designed as a rolling bearing. Such a rolling bearing can similarly be placed in a die-casting mold and coated with a synthetic material, while the rolling elements are not coated together. Another variation can be a two-component injection molding process, in which the sliding bearing is formed based on a synthetic material. For this purpose, graphite materials combined with the synthetic material can be used, for example.

[0014] Advantageously, the pump-side bearing assembly and reinforcement are cast under pressure using a high-performance synthetic material in the injection molding process according to the invention, thereby producing a one-piece device. Die casting molds and injection molding are proven and well-known in the processing of high-performance synthetic materials, especially in the manufacture of high-volume parts where high manufacturing tolerances are required while simultaneously reducing manufacturing costs.

[0015] The device with integrated bearing assembly according to the present invention can be used for connecting the pump components of a slotted tube motor and a centrifugal pump. At the same time, the present invention advantageously separates the stator and rotor of the slotted tube motor in a sealed manner and avoids eddy current losses during its operation.

[0016] A particularly advantageous feature is the integrated design of the device as a structural assembly, which, according to current technology, consists of a pressure cap, a synthetic gasket, an O-ring, and a sliding bearing. In another variation of the invention, this integrated structural assembly can be supplemented with a cast-in reinforcement, which can be designed as a wound piece or a carbon fiber tube, thereby further reducing installation steps. Attached Figure Description

[0017] Other features and advantages of the invention will become apparent from the description of the embodiments with the aid of the accompanying drawings and from the drawings themselves.

[0018] in: Figure 1 A cross-section of a centrifugal pump with a slotted tube motor is shown. Detailed Implementation

[0019] Figure 1A cross-section of a centrifugal pump with a slotted tube motor is shown. The slotted tube motor has an impeller 2 arranged within a housing 1. Fluid enters the pump chamber from below and is axially conveyed to the impeller 2. The rotating impeller 2 transfers kinetic energy to the fluid, which accumulates in a gradually tapering pressure pipe and exits the pump chamber upwards. The impeller 2 is mounted on a shaft 10 driven by a slotted tube motor consisting of a rotor 6 and a stator 5. The slotted tube motor has a device 3 for connection to the housing 1. The device 3 includes a connector 15 integrally constructed with an element 8 for separating the rotor 6 from the stator 5.

[0020] Device 3 is constructed of a synthetic material, preferably a high-performance synthetic material, which is advantageously temperature- and pressure-stable and non-conductive. Element 8, according to the invention, is designed as a tubular component that functions as a slit tube and completely seals the rotor 6 from the stator 5. The centrifugal pump operates as a wet rotor, whereby the rotor 6 is cooled by fluid and the bearing assembly 14 is simultaneously lubricated by fluid. A connector 15 is formed on the pump side of element 8, to which the housing 1 is indirectly or directly fixed, thereby sealing the pump chamber of the impeller 2. Thus, connector 15 functions as a pressure cover.

[0021] The bearing assembly 14 is integrated into the device 3 by molding, preferably by injection molding. The bearing assembly 14 is preferably designed as a sliding bearing. However, it is also conceivable that the bearing assembly 14 is in the form of a rolling bearing. The bearing assembly 14 enables the shaft 10 to perform functional movements. A rotor 6 is mounted on this shaft. An axial bearing 13 is installed between the bearing assembly 14 and the rotor 6.

[0022] The second bearing assembly 11 is integrated into the end bearing cover 9, which supports the motor-side end of the shaft 10. The end bearing cover 9 is fitted into the motor housing 7, which acts as a second protective layer to securely and sealably enclose the slotted tube motor. For sealing, a seal 12, preferably an O-ring, is arranged between the end bearing cover 9, the motor housing 7, and the element 8. The stator 5 is mounted between the element 8, which has a reinforcing member 4 cast according to the invention, and the motor housing 7 in a manner that encloses the rotor 6.

[0023] The reinforcing member 4 can be designed as a reinforced tube made of carbon fiber or as a wound part made of carbon fiber reinforced synthetic material strip. Advantageously, to improve stiffness, the reinforcing member 4 is placed in a die-casting mold and cast together with the bearing assembly 14 using a high-performance synthetic material, thereby producing an integral device 3. The wall thickness of the element 8 combined with the reinforcing member 4 is less than 2 mm, preferably less than 1.5 mm, and especially less than 1 mm.

Claims

1. A centrifugal pump having an impeller (2), said impeller being arranged in a housing (1) and driven by a slotted tube motor, wherein, The slotted tube motor has a device (3) for connection with the housing (1), and the device (3) includes a connector (15) integrally constructed with an element (8) for separating the rotor (6) of the slotted tube motor from the stator (5). The device (3) is characterized in that it has a bearing assembly (14) form-fittedly integrated into the device (3), wherein a reinforcing member (4) is arranged at least partially around the element (8), the reinforcing member (4) form-fittedly and / or material-fittedly integrated into the device (3), wherein the reinforcing member (4) is placed in a die-casting mold and cast together with the bearing assembly (14) using a high-performance synthetic material to produce the integral device (3).

2. The centrifugal pump according to claim 1, characterized in that, The bearing assembly (14) is integrated into the device (3) by molding.

3. The centrifugal pump according to claim 2, characterized in that, The bearing assembly (14) is integrated into the device (3) by injection molding.

4. The centrifugal pump according to any one of claims 1 to 3, characterized in that, The device (3) is made of synthetic materials.

5. The centrifugal pump according to claim 4, characterized in that, The device (3) is made of a heat- and / or pressure-resistant synthetic material.

6. The centrifugal pump according to any one of claims 1 to 3, characterized in that, The wall thickness of the assembly consisting of the reinforcing member (4) and the element (8) is less than 2 mm.

7. The centrifugal pump according to claim 6, characterized in that, The wall thickness of the assembly consisting of the reinforcing member (4) and the element (8) is less than 1.5 mm.

8. The centrifugal pump according to claim 6, characterized in that, The wall thickness of the assembly consisting of the reinforcing member (4) and the element (8) is less than 1 mm.

9. The centrifugal pump according to any one of claims 1 to 3, characterized in that, The bearing assembly (14) includes a sliding bearing and / or a rolling bearing.

10. A method for manufacturing a centrifugal pump according to any one of claims 1 to 9, characterized in that, The bearing assembly (14) is connected to the device (3) by forming a material lock-in and / or shape lock-in.

11. The method according to claim 10, characterized in that, The bearing assembly (14) is material-locked and / or shape-locked to the device (3) by injection molding of synthetic material.

12. Application of a device (3) having an integrated bearing assembly (14) in a centrifugal pump according to any one of claims 1 to 9 for connecting a slotted tube motor to the housing (1) of the centrifugal pump.

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