EP1965081A1 - Centrifugal pump with coaxial magnetic coupling - Google Patents

Abstract

A centrifugal pump has static and closed housing/walling (1) for the feed liquid within the pump, and a contactless permanent-magnetic coaxial rotary coupling (6,7;13,14) for transmission of a drive torque within the pump housing. A pump impeller (4) forms an open unit with a magnet rotor (6). Between the magnet rotor (6) and a magnet driver (13) is a partitioning wall facing the opening of the pump drive-face, and the magnet driver (13) is mounted in at least one rolling bearing (16a; 16b) adjoining the pump.

Description

The invention relates to a centrifugal pump having the features of the preamble of claim 1, as shown in DE 298 22 717 U1 is known.

The centrifugal pumps with magnetic coupling represent an important type of industrially used machines for the conveyance of liquids. Compared to the simpler centrifugal pumps with mechanical seal they have the advantage of a hermetic seal of the pump chamber. This makes them especially favorable for the promotion of aggressive or toxic liquids.

In most cases executed coaxial rotary joints with radial arrangement of the magnets and corresponding radial magnetic action lines are used. Only this type is further considered below and is also the subject of the application.

Based on this, the present invention seeks to improve the radial bearing in the magnetic coupling of a generic centrifugal pump. to Solution of this problem, a centrifugal pump with the features of claim 1 is proposed.

If the magnet driver has at least one arranged in the region of the interior of the impeller magnetic rotor unit bearing, thereby the pump length can be significantly reduced despite independent storage of the magnetic driver within the pump. For the magnetic drive bearing bearings are preferably used. The rolling bearing of the magnetic driver remains unaffected by the pumped liquid. For this purpose, a known ansich known, disposed between the magnet rotor and the magnet driver split pot. The magnet driver preferably has an open towards the drive side cup shape to receive the at least one bearing of the magnet rotor within the pump housing. A particularly advantageous mounting of the magnetic driver is achieved by a hollow hollow cantilever, through which the drive shaft of the magnet driver is guided, and which preferably carries on at least one inner or outer surface at least one of its end portions a bearing for the magnet driver. Tapering in these end areas facilitate the placement of such bearings in a small space. When the taper is made from the root of the cantilever, high bearing forces can be absorbed in a lightweight construction.

The at least partial storage of the magnetic driver within the space defined by the impeller magnetic rotor unit and the embodiments of such storage are of independent inventive significance.

The above-mentioned and the claimed components to be used according to the invention described in the exemplary embodiments are not subject to special conditions of size, shape, material selection and technical design, so that the selection criteria known in the field of application can be used without restriction.

Fig. 1

eine erste Ausführungsform;

Fig. 2

eine zweite Ausführungsform;

Fig. 3

eine dritte Ausführungsform;

Fig. 4

eine vierte Ausführungsform;

Fig. 5

eine fünfte Ausführungsform;

Fig. 6

eine sechste Ausführungsform;

Fig. 7

eine siebte Ausführungsform;

Fig. 8

eine achte Ausführungsform sowie

Fig. 9

eine neunte Ausführungsform.

Further details, features and advantages of the subject matter of the invention will become apparent from the subclaims and from the following description of the accompanying drawings, in which - by way of example - a preferred embodiment of the inventive arrangement of a centrifugal pump is shown with coaxial magnetic coupling. In the drawing show:

Fig. 1

a first embodiment;

Fig. 2

a second embodiment;

Fig. 3

a third embodiment;

Fig. 4

a fourth embodiment;

Fig. 5

a fifth embodiment;

Fig. 6

a sixth embodiment;

Fig. 7

a seventh embodiment;

Fig. 8

an eighth embodiment as well

Fig. 9

a ninth embodiment.

The embodiments have in common that they have a suction nozzle 2 and a discharge nozzle 3 exhibiting pump housing 1, wherein a pump impeller 4 is mounted coaxially with the suction nozzle and is fluidly connected in the radial direction with the discharge nozzle 3. The pump impeller 4 has on the drive side a magnetic rotor 6, with which it forms an open to the drive side impeller magnetic rotor unit. This has on its outer circumference on the rotating part 9 of a sliding bearing, while the fixed part 10 of this slide bearing on the Inner wall 20 of the pump housing 1 is arranged. On the radially inner side of the magnet rotor carries 6 permanent magnets 7. These are opposed to permanent magnets 14 with a radial distance, which are arranged on the outer surface of an approximately cup-shaped magnet driver In all embodiments, a partition, possibly in the form of a so-called split pot 12, which keeps the magnetic driver dry against the liquid-wetted interior of the pump, is interposed between the magnet rotor and the magnet driver. The magnet driver 13 is supported at two axially spaced locations via rolling bearings 16a and 16b. This storage is in all embodiments - although not mandatory - each with respect to the pump housing 1 instead, said storage in the embodiments according to FIGS. 1 to 9 at least on the pump side takes place within the space formed by the impeller magnetic rotor unit 19. For this purpose, a continuous hollow Kragzapfen 39 from the drive-side housing end wall to the pump side down and has a tapered design 39a, 39b, wherein at its drive end portion which penetrates the drive shaft 15 of the pump is roller-mounted, while a second roller bearing in the opposite end on his Outside the drive shaft 15 indirectly, namely superimposed on the magnet driver 13. The latter has for this purpose on the drive side open cup shape.

The outer circumference of the impeller magnetic rotor unit 19 can now - be used to accommodate the rotating part 9 of the slide bearing - with complete freedom of design and generous axial extent and does not have to be as thin as possible in the prior art, for economic reasons, protective jacket 8. This, too, had led in the prior art to the need for further radial startup and emergency bearings 37, which are no longer needed here in any way. It is even possible, with a suitable choice of material and with appropriate shaping, that parts of the magnet rotor 6 itself can become the rotating part 9 of the slide bearing.

Since all parts of the coaxial magnetic coupling are located radially further inside, the fixed part 10 of the slide bearing can be easily brought directly to the stable inner housing 20 of the pump housing 1 and no longer needs disadvantageous be the principle thin wall of the split pot 12. It is even possible, with a suitable choice of the material and with appropriate shaping, that parts of the housing wall 20 of the pump housing 1 itself can become the fixed part of the plain bearing 10, possibly even by a multi-layered design.

For an effective slide bearing, it is irrelevant whether 9,10a and 9,10b is stored in two explicit bearings, or whether the entire slide bearing is pulled apart into a single axially extending "storage drum". Also, combinations are conceivable, ie explicit rotating bearing 9a and b against fixed bearing 10 as an axially extended drum and vice versa.

In the case of a - in practice frequent - malfunction of the pump over massive gas entry (air or evaporated fluid in consequence cavitation), the residual liquid remaining in the pump will accumulate as a thrown off ring on the outer circumference in the pump housing 1. In the case of a corresponding pump, the slide bearing 9, 10 is arranged exactly here, which can be operated as long as desired with the residual liquid with sufficient cooling. However, with very small residual amounts, which tend to occur at high delivery heights of the pump and low static counter-pressure, it can not be ruled out that these can escape axially in order to move to even higher radial levels in the impeller. This can be prevented via a lock in the form of a circulating ring 21. If the inner diameter of the circulating ring 21 is selected to be smaller than the contact diameter between the plain bearing halves 9 and 10, then the enclosed and rotating liquid ring 23 will always wet the plain bearing 9, 10. Another advantage of this design results in the stoppage of the pump, namely, when the circulation ring 21 prevents complete emptying of the pump in the region of the sliding bearing 9, 10. If the pump is then restarted without a liquid is present at the suction nozzle 2, which is also a frequent operating error, then the slide bearing 9, 10 is still sufficiently lubricated with the remaining liquid in the liquid retention chamber (22) liquid template and their axial escape during rotation also prevented by the lock.

The invention can be exploited to significantly shorten the axial extent of the pump. This is possible by the magnetic driver 13 is not stored in the pump housing 1, but is placed directly on the shaft journal of the engine, so is ultimately stored by the prime mover. This is usually an electric motor. The electric motor is flanged directly to the pump, which is known as "block construction".

Advantage of this construction is in addition to the effect of axial shortening the savings of the two bearings 16. The disadvantage of this design is that the magnet driver 13 is no longer part of the pump and thus complete assembly of the pump can only be done if the driving motor present is. However, its size is initially at least in industrial pumps an unknown size and will be determined only on the basis of customer information. Thus, the time of final assembly of the pump is necessarily relocated behind this time and is also still an individual assembly with the known economic disadvantages.

Towards a better solution is in accordance with FIG. 1 initially a, preferably detachable, split pot 12 introduced, as it always finds use in industrial pumps. In practice, these splitters are made very thin-walled on the circumference in order to realize the smallest possible radial gap between the magnet rotor 6 and magnet driver 13 can. Due to the design of the split pot 12 can be performed with a smooth end wall and must point with its larger opening in the direction of the drive side. Although the split pot 12 itself should not be used to support a rolling bearing because of its thinness, but now offers according FIG. 1 in its inner region 24 sufficient space for an axially generously sized rolling bearing 16 of the magnet driver 13. Thus, the axial Baumass the pump can be reduced to that of the conventional block design, however Here, the magnetic driver 13 is part of the pump, which allows a complete series assembly and stockpiling of the pump.

The shaft end 25 in such an axially shortened construction can advantageously according to FIG. 2 be carried out so that either via a conventional pump clutch (shown only the pin portion 27 of the pump clutch) the direct connection of a motor is possible (which could be flanged via an intermediate ring also directly to the pump) or a shaft journal 28 again with the conventional pump free shaft end leads (eg to comply with specified standard dimensions). Also, such a shaft end 25 should provide the opportunity to attach an additional flywheel 26 to compensate for the mentioned disadvantage of the type B chosen here when starting the pump can. All this would be part of the final assembly of the pump unit (which would also be carried out by the user of the pump itself) and would still allow a large-scale series assembly and cheap stockpiling of the pump at the manufacturer as described above.

The rotating part 9 of the plain bearing need not necessarily consist of two defined bearing sleeves a and b or from the magnet rotor 6 itself, but can FIG. 3 also as an axially continuous sleeve 29 (FIG. FIG. 3 , upper half) or molding compound 30 ( FIG. 3 , lower half).

This offers economic advantages, especially if these components according to FIG. 4 also still serve to protect and seal the radially lower magnet rotor 6 and the permanent magnets 7. Namely, it is quite common, depending on the field of application of the pump, that the magnet rotor 6 as ferromagnetic carrier of the permanent magnets 7 must be protected from the attack of the liquid to be conveyed and not as the pump impeller (4) may come into contact with the liquid , The now assumed difference of the materials between pump impeller (4) and magnet rotor 6 is expressed in a different hatching

The desired completely contact-free and thus wear-free and low-friction sliding of the impeller magnetic rotor system 19 in the pump housing 1 is opposed by the high peripheral speed of this arrangement. By additional dimple-like recesses or elevations on the surface of the rotating plain bearing 9, e.g. So on the sleeve 29 or the molding compound 30 so-called Taylor vortex in the sliding gap and in the adjacent rotational space of the liquid can be generated, which contribute to the stabilization and the contact freedom of the sliding bearing.

In particular, if in the case of a malfunction in the pump only a liquid ring 23 rotates and a stream of fresh lubricant fails, this residual liquid will heat up in the plain bearing due to friction until a heat transfer equilibrium with the pump housing 1 is reached. Due to the direct contact of the sliding bearing 9, 10 with the pump housing 1 is here by attachment of outer cooling fins 32 (FIG. FIG. 6 ) a directly effective way of increased convective heat dissipation and thus the reduction of the stationary temperature of the liquid ring 23 at a prolonged malfunction. In the upper half of FIG. 6 is a Querverrippung shown in the lower longitudinal ribbing. This latter should be more useful in practice, since this can be used to advantage the already existing cooling air flow of the driving electric motor, which always takes place in the direction of the pump.

In order to prevent the lack of lubrication of the sliding bearing 9, 10 even in the case of a corresponding malfunction, the supply of external lubricating fluid ( FIG. 7 ) and / or a sensory monitoring (eg temperature, vibration, structure-borne noise) of the slide bearing 9, 10 loud FIG. 8 proposed. Here, the proximity of the slide bearing 9, 10 to the pump housing 1 acts so that this access can be done very easily.

Many designed magnetic coupling pumps, which are particularly suitable for conveying aggressive, abrasive and hazardous liquids due to the hermetic seal of the pump interior, are in the wetted area of the pump housing. 1 lined with about a plastic layer or composed of several - usually two - material shells. Ultimately, then the innermost layer of material 35 must have the desired properties with respect to the liquid, while the outer shells serve more the shape and stability to the internal pressure of the pump. FIG. 9 makes this construction also for the present invention. Since in particular the mentioned plastic materials (eg PTFE or PE) can be used very well as a sliding bearing material in mixed friction region, a construction is proposed, as shown in Figure 15 in the lower half. If, on the other hand, the material of the innermost material layer 35 is not suitable for plain bearings, the construction in the upper half of FIG. 15 must be used.

LIST OF REFERENCE NUMBERS

1

pump housing

2

suction

3

pressure port

4

Impeller

5

impeller shaft

6

magnet rotor

7

Permanent magnet (rotor)

8th

mantle

9

rotating plain bearing

9a

rotating plain bearing, impeller side

9b

rotating plain bearing, drive side

10

fixed plain bearing

10a

Fixed plain bearing, impeller side

10b

Fixed slide bearing, drive side

11

bearing insert

12

containment shell

13

magnetic driver

14

Permanent magnet (driver)

15

drive shaft

16a

Rolling bearing, impeller side

16a

Rolling bearing, drive side

17

axis

18

flow ribs

19

Impeller-magnetic rotor unit

20

Inside wall of the pump housing

21

circumferential ring

22

Fluid retention area

23

rotating amount of residual fluid

24

Interior of the containment shell

25

shaft end

26

Inertia

27

Spigot part of a pump coupling

28

shaft journal

29

shell

30

molding compound

31

recesses

32

cooling fins

33

Access for lubricating fluid

34

Access for sensors

35

Innermost material layer

36

sealant

37

Approach or emergency camp

38

Outer circumference of the impeller magnetic rotor system

39

collar journal

39a

rejuvenation

39b

rejuvenation

LITERATURE

• [1]
  Brochure of
  Company WERNERT-PUMPEN GMBH
  D-45476 Mülheim an der Ruhr
  Standardized chemical pump made of plastic with magnetic coupling - NM series
  Issue 687/02
• [2]
  Brochure of
  Company IWAKI pumps
  lwaki magnet driven pumps - MDM series
  printed in Japan 99.11.ITN
• [3]
  Brochure of
  Company CP-Pumpen AG
  CH-4800 Zofingen:
  Magnetic coupling pump MKP, metallic
• [4]
  Robert Neumaier: Hermetic pumps publishing house and image archive WH Faragallah, 1994 ISBN-3-929682-05-2
  Chapter 3.7.12 Wave-less magnetic-coupling centrifugal pumps p. 356 ff

Claims (8)

rotary pump - With a static and closed enclosure of the pumped liquid inside the pump in the form of a housing (1), - With a non-contact, permanent magnetic coaxial rotary joint (6, 7, 13, 14) for transmitting a drive torque in the interior of the pump housing - With a pump impeller (4), which together with a, permanent magnets (7) carrying, magnetic rotor (6) forms a sliding, open to the drive side, cup-shaped structural unit (impeller magnetic rotor unit 19), - And in which the magnetic lines of action of the driving part of the rotary joint (magnetic driver 13 and permanent magnets 14) facing radially outward and the magnetic lines of action of the pump impeller (4) connected to the rotary coupling part (magnet rotor 6 and permanent magnets 7) radially inwardly point, - In which between the magnetic rotor (6) and magnet driver (13) a partition wall is arranged, which faces with its opening the drive side of the pump and the liquid inside the pump from the magnetic driver (13) separates, and in the - The magnet driver (13) in at least one bearing connected to the pump, such as a rolling bearing (16) is mounted, and in the - At least one impeller side bearing, such as a roller bearing (16 a), in the inner region (24) of the pump housing is located and - The storage of the magnetic driver (13) takes place without contact with the partition. characterized in that the at least one impeller-side bearing is located in the interior of an inside hollow magnetic drive (13). Centrifugal pump according to the preamble of claim 1, characterized in that the impeller-side bearing of the inner ring is fixed and rotates the associated outer ring with the mounted magnetic driver (13). Centrifugal pump according to claim 2, characterized in that a drive-side bearing, such as roller bearings (16b) is provided, whose inner ring rotates with the mounted drive shaft (15) and the associated outer ring is fixed. Centrifugal pump according to the preamble of claim 1, characterized in that a continuous hollow, in the pump housing (1) from the drive side protruding Kragzapfen (39) is provided for receiving the drive shaft (15) and connected to the pump housing or connectable. Centrifugal pump according to claim 4, characterized in that the hollow cantilever (39) has a taper (39a, 39b) at least in one of its end regions. Centrifugal pump according to one of claims 1 to 5, characterized in that the region of the drive-side end (25) of the drive shaft (15) is formed so that it has a flywheel (26) or is providable. Centrifugal pump according to one of claims 1 to 6, characterized in that the region of the drive-side end (25) of the drive shaft (15) is designed such that it optionally with a flywheel (26), a pin member (27) of a pump clutch and / or a Shaft journal (28) is releasably connectable. Centrifugal pump according to one of claims 1 to 7, characterized in that the magnetic driver (13) has an open towards the drive side cup shape.

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