DE2355104A1 - Rotating spindle with electromagnet controlled axial position - soft iron disc rotates on spindle between annular windings - Google Patents

Abstract

A rotating spindle for a sealless rotary pump is positioned both axially and radially by means of a soft iron disc mounted coaxially on the spindle by a ring. The disc rotates in an axial space formed between two annular magnetic cores which have annular electrical windings disposed inside them to produce two toroidal magnetic fields each toroidal magnetic circuit being completed by way of the disc. In this manner radial movements of the spindle are avoided by the production of induced currents in the disc which beget a centring effecting on the spindle. Axial movements are prevented by known control circuits which adjust the currents in each of windings in response to axial movements of the spindle.

Description

RHOWM, BOVEB! & CiE ■ AKTSENGESTLSCHAFT. ; '.' ϊ ■ ') ['';''· *?

MAhiNHtlf «« - BROWN BOVLrU

Kannlaeim, October 23, 1973

PAT-Fs / Bt ■; ; .'.'-. '

Electromagnetic thrust bearing

The invention relates to an electromagnetic thrust bearing rait electromagnetic devices counteracting the axial thrust. . "-":

Magnetic relief devices for Yertical machines (e.g. hydropower generators, synchronous phase shifters) known for a long time (DT-PS 824 251 and ΞΤΖ-Α, Volume 86, 1965, pages 340 to 341). The purpose of these bodies is to counteract the downward axial thrust (e.g. the weight of the runner), relieve the load on the bearing and to reduce the "frictional losses". The magnets are ring-shaped constructed and have one or more excitation windings, possibly also compensation windings, the harmful Stray flux in the shaft and in the construction parts avoid. The armature disk rotates with the shaft. If a complete relief is provided, the magnetic force j holds the axial thrust alone the equilibrium. The equilibrium position can be stabilized by suitable control of the excitation current become (DT-PS 872 137) - '

Next is a magnetic floating bearing for a standing one Shaft, in particular the runner shaft of an electricity meter; with one that maintains the shaft in its vertical position] magnetic stabilizers known (DT-OS 1 472 413). ;

509820/0090

F '.; L 4 (1 72 JtOO / KE)

The stabilizing means consists of a magnet round cross-section and one in front of this I-magnet at a distance, .v / calibratable, round disc, with a electrical stabilization control ensures that the height position of the lielle is maintained automatically. A special one Arrangement of this known magnetic levitation bearing sees a soft magnetic disk at each end of the line and in each case an electromagnet associated with the disc.

Furthermore, magnetic bearings are known which achieve stabilization in the axial direction by means of two Dlektronagnete. The two magnets are each attached to the shaft ends (ETZ-B, Volume 13, HeJTt 19 of September 18, 1961, page 525).

For the storage of high-speed, vertical shafts .are also known electromagnetic bearings that work with a U-shaped magnet core at each end of the shaft. The magnets have both load-bearing and centering function (DT-03 2 151 916).

Finally, a magnetic thrust bearing has become known that is based on the electrodsaiamic principle and repulsive Forces (only at higher speeds) generated (DT-OS 2 219 029).

The present invention is based in particular on an electromagnetic axial bearing with electromagnetic devices counteracting the axial thrust in the form of stationary electromagnets arranged rotationally symmetrically around the shaft and an annular or disk-shaped armature that is attached to the shaft and revolves with the skin. There is an electrical control system which, by means of ⁵⁵ ", keeps the armature in a contact-free, stable equilibrium position, as is known, for example, from DT-PS 872 137 mentioned at the beginning.

* Control of the excitation current;

509828/0090. bad qmginal

j The object of the invention is now to provide such a

! To train bearings in such a way that there are forces "in both directions"

! can take or ^{exercise on the T} .7elle. Furthermore, through the

j ■ - --.._ ■■ "" ■.

^: Invention of a double-acting, electromagnetic AxIaI-l bearing to be created, which, in contrast to known electro: magnetic axial bearings, which consist of two unilaterally opposing bearings, a more compact design I and special conditions of use and "promotions better I can correspond to the comparable known bearing designs

• guides. For example, the novel axial bearing should be

• be suitable to be used in a liquid environment,

j where, under such operating conditions, lower friction

I strive for losses:

I To achieve the above objects, an electromagnetic ■ '■■ MOORISH thrust the vice end type in question according to the invention! designed such that z \ fei fixed ■ _{"rotationssynmetrls'Ghe.} j electromagnets are provided -the your .Polflächen one other gegenüber3-ying and between which in each case-by!

Gap separated - which is designed as a magnetically soft running disk formed 'common anchor arranged 1st.:';

; According to a special embodiment of the invention, the Anlcerl disc of the electromagnetic device be designed in such a way that I that the profile of the disc towards larger diameters

• rejuvenates. In l \ ^T of the invention can thereby eiterbiläung the .PoI-

I areas of the magnets as well as. the load-bearing surfaces of the anchors disc in staggered, perpendicular to the axis of rotation, j planes are parallel to one another, while those are not

I taper the load-bearing parts of the armature disk towards larger diameters.

'* ------ - ■: ---- BAD ORIGINAL

509820/0090

.-. 660/73

The invention seeks to suppress τοη harmful leakage fluxes Finally, before that between the magnet core

ί standing electromagnet and those parts of the housing or frame to which the slektromagnets are attached, a Layer made of non-magnetic material is arranged, provided that the housing "or the frame itself is made of ferromagnetic material consists. ;

A particular field of application of the invention are those without stuffing boxes Circulation pumps and it is accordingly proposed that the bearing according to the invention as an electromagnetic axial bearing to be provided for such pumps, since it has been found that magnetic Axial bearings for circulating pumps without a stuffing box are superior to the water-lubricated plain bearings currently in use. ■

The bearings now used in these pumps show undesirably high signs of wear at low speeds (start-up and run-down phase, slow driving of the pump with the drive motor switched off). Magnetic axial bearings work against it! wear-free, so that a considerable increase in the pump running time can be expected. In addition, _the: magnetic bearings can easily cavitation shock loads. In the case of cavitation with water-lubricated bearings, there is a risk that the hydrodynamic lubricating film will break through and the bearing will be damaged. '. Magnetic bearings can be built in such a way that they leave enough play in the axial direction of the shaft with the intention of using the mass inertia of the "shaft" to dampen the cavitation impacts.

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509820/0090

ι ■ ·. ! ■ 1 π / 2 11;:>.! :> r

ΙBei the stopfbüchslosen circulators mentioned is thus a "replacement of the current Axillagers advantageously Hagnetlager in many iEinsicht. The magnetic bearing needs in this application '■ case of use in the rest no .zentrierenden properties ttciben to _u as separate guide bearings are available. The task ;; öes Kagnetlagers here is the axial thrust ^in, contact-free to produce any operating case, a task that can be solved in that the position of the pump ^shaft;:. sensed and wird- regulated the shear forces occurring amount J in both directions some Mp, ■, - '.]'

_: For various reasons, the known magnetic bearings mentioned at the beginning are not suitable for use as axial bearings for circulating pumps without stuffing boxes. In contrast to the known magnetic relief devices (e.g. DT-PS 824: 231) the pump bearing must be able to exert forces on the shaft in both directions. '. j

The use of two unidirectional bearings - each in; the kind of magnetic relief device - in no way leads to the goal. Are at stöpfbüchslosen circulation pumps j; yourself known to all bearings and the drive within "the pump housing in water environment · Since the rotieren- in the water '. each bearing part, with increasing diameter; strongly growing. ; "Bring friction losses with them and have an impact on the efficiency of the pump, what counts is the number and dimensions of the running disks _; ! to keep it as small as possible ^ Accordingly, the attachment! of two unidirectional bearings with two washers is ruled out:!: atis reasons for loss. ■ '·

I ■ - = ;. ■■ -. ■

At least there are no orders with unilateral effects ^ Bearings in question, their running washers on the shaft ends are long (see the DT-GS mentioned above h 472 413). Since the upper end of the shaft is the blading of the circulation

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Pal '! F 1 (1Γ? Ί SOO-Cl;

_..._. 660/72

pump carries and the middle part is provided for the drive motor the axial bearing acting on both sides can only be attached to the lower shaft end.

The aforementioned difficulties that are common to the use counteract magnetic bearings or magnetic relief devices for circulating pumps without stuffing boxes, are overcome by the camp according to the invention. For bearings, which are located in a liquid environment, the bearing friction itself is considerably high. These frictional losses are kept relatively small in the electromagnetic axial bearing according to the invention, which acts on both sides, that only one running disc is available. The losses can be reduced even further if the arrangement is so made is that the profile of the armature disk - as already stated above - tapers towards larger diameters.

Further details and advantages of the invention emerge from the following description of preferred exemplary embodiments: and from the drawings. · _:

It show: · ■

Fig. 1 is a sectional view of the basic arrangement of the double-acting electromagnetic according to the invention Asiallager, - ';

Fig. 2 shows a possible embodiment of the profile taper of ^:

Armature disk and;

Fig. 3 shows the basic flow of flux when a [

Electromagnet, if a leakage flux spreads over ferro- \

forms magnetic housing parts. I.

- ■ 7 -

509820/0090

Pat 4 Γ! Πί? 11500 '"Kl.

BATH ORIGINAL

- ι -

§60 / 75

In figure 1 is T with the _shaft; for example the wave one
Circulation pump without stuffing box, which is otherwise in the
Figure 1 is not shown. The circumferential armature, designed as a soft magnetic disk 2, is attached to the " ^{1 jar 1,}
as indicated by the ring 7, for example. With
3 are the magnetic cores of the electronic magnetic device. ^: draws that from: two fixed part, rotationally symmetrical; Electromagnets, which 'with, their poles each other
opposite and between which _r by one:
Gap separated - the rotating anchor disc 2 is arranged.
Each of the magnetic cores 3 has an annular recess
or groove for / receiving the annular excitation winding 4. The
soft magnetic armature disk 2 v / ird seated on the shaft t. ; due to magnetic forces contact-free between the two electro-magnets; 3, 4- held. The axial guidance: the shaft "."!
else can be in .bekannter ¥ achieved in that the anchor ■■ "disc with the aid of an electrical control system that is shown in ι Zeichnung.nicht, in a non-contact,
stable equilibrium is maintained. For example, can
the position of the shaft can be detected with non-contact transducers and regulated to a constant value via the excitation of the magnets. . . ". '" ..-. ' _: -:

In a modification of the embodiment of Figure 1, the new _; like thrust bearings acting on both sides are also designed in such a way that the electromagnets (as is known, for example, from magnetic discharge devices) carry two .or X several annular windings, the magnetic cores ^j zv / ei or several annular Have grooves · and, for example, E-profile
assume, as Figure 2 shows. The magnets τ \ can also be adapted to different thrust forces in the two axes' Vi

directions - bavr have different sizes. different ^{: be} designed. -:; . . ^":: |

- ■ 8 -

50 9 8 20 700 9 0

.- 8th

__ 660/73

As already mentioned at the beginning, the friction losses can be further reduced if the profile of the soft magneti see anchor disc tapered towards larger diameters. This measure is not only applicable to bearings for stuffing box-I loose circulation pumps in which the bearing is in a liquid area, but also when the warehouse is dry j (air or gas environment) significant, if as low as possible j centrifugal masses (or high critical speeds) are important.

j Figure 2 shows a possible embodiment of the profile tapering. The pole faces of the magnets lie in staggered, parallel planes; the axis of rotation of the shaft 1 is vertical at these levels. Another possibility exists in that the pole faces (apart from the innermost ring face) are slightly beveled, so that the running disk 2 increases takes the shape of a discus.

The tapering of the running disk profile has to be done in such a way that the magnetic flux in the running disk is ordnungsi is managed accordingly. In particular, care must be taken that j does not magnetize individual areas of the disk much more strongly or quickly driven into saturation.

In the realization of the invention that acts on both sides Axial bearings must also be aware of the existence of harmful leakage fluxes that develop through housing and shaft parts can. The stray fluxes cause a non-uniform magnetization of the cylindrical magnet legs, so that make signs of saturation noticeable even with lower excitation currents. It also results from the leakage flux an undesirable reduction in the achievable bearing forces.

509820/0090

4 I 'I (17211500.-Ll

"'_ 660/73

FIG. 3 illustrates the flow of flux when a magnet is excited and, in addition to the Huta flux ^ ^, there is also a leakage flux φ ^ which flows, for example, over ferromagnetic housing parts.

In order to suppress harmful leakage fluxes, the use of compensation windings has been proposed for magnetic relief devices (see, for example, D ¹ E-PS 824 231 mentioned at the beginning). Coil compensation windings can also be used in principle for electromagnetic axial bearings acting on both sides. However, if one thinks of the described use of the bearing according to the invention in pump construction, the use of compensation windings is ruled out for the following reasons: -,. . ·;

. - The effort is additional with four "■■ -" -. required turns too large. '- There are higher losses of excitation. - Because of the water environment anyway

existing insulation problems will be \ considerably more difficult. ·. :

To reduce the leakage flux, another measure is proposed within the scope of the invention, which is shown in FIG is shown. The suggestion is to use a non-magnetic Layer 6 between the magnetic core 3 and those parts of the Insert housing 5 to which the magnet is attached. This intermediate layer β can be made of non-magnetic steel, for example j or made of plastic? Of course, the surrounding medium can also partially fill the gap. Because of the high magnetic reluctance of the non-magnetic layer 6 are the leakage flux that is via ferromagnetic Housing parts as well as via guide bearings and shaft parts = form can, on a harmless: measure her down. . '

. 50 9 8 20/00 90

Pal4f-1 (172 115UOiKCl .. ..- '. "-.-.--

660/73

τ 10-

The possible uses of the subject matter of the invention are by no means restricted to circulating pumps without a stuffing box. . According to the invention formed magnetic thrust bearing prospects for further advantageous use also "other Punpentypen or eg with blowers have The subject invention is generally used for two-sided, axial superposition of waves of interest are those electromagnetic axial bearing, especially under special operating conditions or requirements such as...:

j - ¥ water environment in connection with lower

Speeds

- Demand for freedom from friction

- as a lubricant-free bearing in an aggressive atmosphere

- at extremely high speeds.

In addition, the invention is not limited to the exemplary embodiments described or illustrated, they are hereof various deviations, especially of a structural nature, are conceivable. So the ¥ elle 1 needs for its storage the invention Storage is provided, not necessarily be arranged vertically, it can also be a different location, for example a -take a horizontal position.

- 11 -

50 9820/0090

Pat4F 1 (172 11500 KE)

Claims (1)

- 11 - Claims Electromagnetic axial bearing with aera axial thrust counteracting elrtromagnetischen Einrich ^ Form of rotationally symmetrical around the skin arranged fixed electromagnets and a ring or disk-shaped armature attached to the shaft, revolving with the shaft, whereby an electrical control system is available, which is controlled by the excitation current Holds the armature in a contact-free, stable equilibrium position, characterized in that two stationary, rotationally symmetrical electromagnets are provided which have their poles opposite one another and between which - each separated by a gap - as a soft magnetic running disk (2) formed, common anchor is arranged. Electromagnetic thrust bearing according to claim 1, characterized by characterized in that the magnetic core (5) of the fixed Electromagnet one or more annular recesses or grooves for receiving the annular excitation winding (4-). ~ ;; ■ ■ Electromagnetic axial bearing according to claim 1 or 2, characterized in that the fixed electromagnets are adapted in terms of magnetic force and size to different. Shear forces in the two axial directions ^ 'are designed differently. 4. Electromagnetic axial bearing according to one of claims 1 to 3t, characterized in that the armature disk (2) of the electromagnetic device is designed so that the profile of the disk tapers towards larger diameters. '. "'■■' ■■ - ■ ■■■■ ■ - -12 -, ■■■ ^: 509820/0090 Pat 4 F 1 (1 72 USOO.'r Γι ■ ■ _ 660/73 5. Electromagnetic axial bearing according to claim 4, characterized
characterized in that the pole faces of the magnets as well as
the load-bearing "areas of the armature disk (2) in staggered, perpendicular to the axis of rotation, mutually parallel planes, while the non-structural parts ^themselves, the armature disk to larger diameters taper ^towards: . (Fig. 2). j 6. Electromagnetic axial bearing according to one of claims i 1 to 5, characterized in that between the magnetic core (3) of the fixed electromagnet and those; Parts of the housing or frame to which the electromagnets are attached, a layer (6) of non-magnetic Material is arranged, provided the housing or the frame. • even made of ferromagnetic !!! Material-consists. 7. Application of the electromagnetic bearing according to one of the
Claims 1 to β as axial bearings for circulating pumps without stuffing boxes. '5 09820/0090 Pat ■) F 1 (172 11500 / KEi