DE1428239A1 - Turbomolecular vacuum pump - Google Patents

Description

PATENT ADVOCATE HAMBUHG 8 ·· MBUSS WALL «II · FJHNRUF 84 83 28 UNS 8β« 15

Sqciete Nationale ά'.Etude et de Cons de Moteurs d ¹ Aviation

15o, Boulevard Hausamann

Paris / Seine / France July 27, 1962

Turbomolecular vacuum pump

The present invention relates to a turbomolecular VakuumpiiTnpe, which is based on the principle of a compressor and is intended to operate in a very low Druckberej c ^v corresponding to the molecular region, di * ¹ Fc "rd <* r> un.cr ^ ₃ ft "e _e s by a Anordnun.3 vo""consecutive slices is achieved, which are alternately stationary and rotatable and inräenen openings rind arranged such that the probability of passage of the molecules in the ejnen direction is larger than in the other .

A device of this type is described in German patent application S 78 973 Ia / 27c of April 12, 1962, "Turbomolekular-Va - '. W .-) ρ" has been described.

essential feature of the present invention

ht that d ^"5 e Pum ^ e _a; has only one direction of flow, wherein the suction on the Vakuumeeite by a • rosee Zuf-hrun ^ ffnun";, which is on the document one side of the disk set, takes place wnhrend the ejection The upstream vacuum takes place on the opposite side, as a result of which the molecules of the dilute gas have a central passageway without a bend and in the rotation of the axis of rotation, and the rotor of the pump

• .009825 / 0378 BAD OWNAL ' _{2 /} ...'

is held by means that exclude any lubricating bearing on the vacuum side. 1428239

According to one embodiment according to the present invention, the The rotor is arranged on a main bearing, which is installed near its center of gravity and has great flexural rigidity, währaid a second camp, assigned to the first, in a certain Is arranged at a distance from the center of gravity and may have a lower flexural rigidity. The mechanical transmission of forces, coming from the rotor, through the said bearings on the pump housing, takes place entirely on one and the same side of the pump, more precisely on the side opposite the vacuum side, so that one can easily say that the rotor is on one in Direction of the vacuum side extending cantilever part is arranged.

The turbo molecular pump of the present invention has other important features, the most important of which are as follows appear:

The main camp mentioned above, which is located near the center of gravity of the Rotor is arranged, is with the rotatable disc set via a piece of pipe and a flange seated thereon, on which the said Set of disks is attached and which is located in a plane which is longitudinally displaced with respect to said bearing;

These bearings have a rotating inner and a stationary one outer part and are between a central motor shaft and a hollow shaft stub that surrounds the latter and on the housing of the pump is attached, arranged, wherein the motor shaft protrudes beyond the end of the hollow shaft stub and in this plane with the Rotor with the interposition of a pipe section, which in turn: surrounds said hollow shaft stub, is connected;

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BAD ORIGINAU

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The Sohmler circuit of the pump and, more generally, the space which can be used for the circulation of the visual agent, are completely sealed off from the vacuum zone

The pump has a vertical axis with a suction ■ opening at the top, while the lubricant is due to gravity in the lower part in a central section, collects apart from the external area adjacent to the vacuum;

An envelope is placed around the rim that contains the lubricant, vaa. ensure that condensation of oil vapors can take place and thus prevent these vapors from reaching the vacuum side

The drying out of the pump in order to pumping and suctioning off the gas part

surfaces adsorbed by the walls brought about by the presence of the aforementioned cooling jacket and, while the pump is running e.g. at a faster speed j I air, by heating from a- ^ sen, by more advantageous ^ se in one facing the flange, a ^ f the sow ^ side ixnd the sur pump Parts preferred type is heated.

Further features of the present invention e-ehen av. <? the following description de ^ b ° i ^ eftio-t ^ ri drawing ^ -n ^ on h »rvor _e Show:

Fip ·. 1 half slnPR T ' ^H n.5rs step it d ^ rch a gemc.ss of the I5rfinusff ^bildungo-Turbono " ¹ -n] r> jl ~ r-Va ¹ ruum-Pump9, b ° i of the"! = ¹ = bor ·: ⁵ z ^ v ^ s? ar- ^I ? ^o ^ '"dret i« tu

t / o .

909825/0378 BADOAfGINAI.

- ♦ - ■■■. ■■■■■■ · '1428 * 39

2 shows a corresponding subdivision of a modified version ** form ml $ 4 * rtical axis of rotation. ^: '

The two flhirbomoltefcul & r vacuum pumps illustrated in the drawing are provided with a series of rotatable disks 1, between which fixed disks 2 attached to the housing 5 of the pump are arranged. Transversely through solids 1 and 2, openings are made in ring-shaped zones marked 3 and 4, which are large enough for the molecules of the thinned lias to pass through. The arrangement and design of these openings are not shown in the drawings for the sake of simplicity and also because they do not appear to be indispensable for a good understanding of the present invention the German patent application "Improvements to Turbomolekular-Vakuumptmpea ¹¹ rerwenden" ^{filed in the same saga;} *.

The turntables 1 have an annular frame 6 larger Thick and parallel faces. Thickness of the annular part let the step or the axial distance between the discs 1 or 2 matched, which has the consequence that when the rotary disks 1 are stacked on top of one another, their annular thickened parts 6 without

Sitting on top of each other, as the drawings clearly show. Man In this way, a seal is created between the outer room A, where the molecules of the "dilute gas" move, and the interior

Room B in the area of the hubs of the turntables 1. These colors 11 b ** - > are equally thick, but they leave between It is easy to create a multitude of small., to avoid sealed chambers between the panes 1 «

909825/0378

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BADORIGiNAt

• m,

the latter are duyoh rods 7 eusanmtn held, which see pa- ' rallei der Hotationeaohae X-Y errbreoken and on one on this

AChse centered cylinder distributed bind to the Ganaan symmetry and j

i give balance. The rods 7 reach through the verdict I

e 6 of the Soheiben 1.,. ·

In the exemplary embodiment, naoh Pig. 1 they also crack down on one Plansch 9, which is arranged in front of the first pane 1, and a plano 1o, which moves backwards to a position between the stack of soles occupies. These paddles 9 and 1o have on their exterior Edge at 9a and 1oa a reinforced part.

The Planpch 1o, which is of annular shape and provided with bores 12, whereby a connection of the space B with the space 0 is created, forms a unit with a coaxial Rohretüok 13, on which by Sohrauben 14 a circular, full-walled, the also circular and full-walled Planoh 9 adjacent cover piece 15 is attached. The pipe section 13 acts with his outer part 13a sliding together with a Rinrrippe 16 on Planoh 9, while a slight play remains between the inner edge of the turntable 1 and the outer surface of the pipe section 13, namely

The aim is to avoid local sealing in room B.

This pipe piece 13 separates however van this space B a iineren RANM D "JID another space B itiroh the Deokelstück 15) the Plansch 9 and the outer part 13a djes tube piece 13 begrens t 'is. At the same time separates the circular, solid-walled Plansoh 9 the

Space towards P, which is connected to the space to be evacuated and ·.

alao is within the vacuum atmosphere, from the inner » Rooms B and B further back, which in turn are opposite

909825/0378

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Space D located within the pipe sections are sealed.

This piece of pipe is arranged around a hollow shaft 17, which has a large diameter over the greater part of its length, but at the end merges into a bearing journal 17a of smaller Durohameter. The shaft 17 is stationary and attached to the housing 5 of the pump! the connection with the rotatable pipe piece 13 is made by ball bearings 18 and 19! the outer ring of the former sits in the cover piece 15 and the outer ring of the second in an annular part 13b seated on the pipe piece 13, while the inner rings are attached to the pin 17a of the stationary shaft and connected to one another by a tubular spacer sleeve *

ver

A closure piece 2o / closes the free outer end of the fixed Shaft 17 »which is slightly set back in relation to the rotatable cover piece 15, while the interior G- of the hollow shaft is connected to the roller bearings 18-19 through small channels 21-21. This arrangement is taken to allow oil lubrication of the bearing, the oil comes from the space G and the return flow through the space D into the interior of the pipe section 13 and as a result of a fixed on the hollow shaft Sämmmelhülse 23 was made by # noses 22 embedded in this shaft

It should be noted that as a result of the tight separation of space D, which contains oil valves, from interior spaces B and E, thanks to the

Lid pieces 15 i | nd of the pipe section 13, and due to the tight, Separation of these last-mentioned spaces from the space against P, thanks to j the flange 9, the roller bearings 18-19 and the lubrication system vollkon men are separated from the vacuum space. Indeed, it is essential

that no trace of oil gets into the room to be evacuated.

909825/0378 BATH

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The drive of the rotatable part, which consists of the disks 1 and their HtXttelemettten 9-10-13, with which they are connected by the rods T SlIlId ₁ , is brought about by an electric motor built into a 4-part pump. This motor, which is of a type that has an air gap in an axial plane, consists on the one hand of a stator. gate 25 in the form of a disk attached to the hollow shaft 17, which is provided with the windings, which can consist of a Wloklungsplatte with Limelleneuleltungen, as well as with the connecting lines to the external feed circuit. On the other hand, the motor has a rotor which can consist of, for example, ferromagnetic ring magnets 26-26. These magnets are attached to a cylindrical housing 27 which has a flange 28 against which the heads 29 of the rods 7 are supported, while the screws jjo , which are ge-Bohraubt on the end of the rods provided with a screw thread 8, support against the end flange 9.

Above all, there must be a special arrangement of the whole rotating part of the pump, in a cantilevered manner on a stationary one Sitting wave, be observed. This arrangement allows all the dangers of vibration in the normal speed range as well as at to switch off an increase in the rotational speed. This arises from the fact that the critical speed of the whole Build up is higher than the rotation speed, despite the use of small diameter ball bearings that allow the high rotation speed s were exposed. The T ^ sun.3 of this problem was facilitated by the great flexibility + eifigkejt that one by arranging des bearing 19 near the center of gravity of the rotatable Part is given "right behind this la" - on the side where it is let in the fixed shaft 17 has a considerable -

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Enlargement of the diameter knife "to j 11 even very rigid parts. The second bearing 18 is only intended to "store the moments around the center of gravity of the rotatable part * to record. The reduced stiffness of ZapfenB 17a of the solid, standing wave between the "two bearings 18 and 19 is none the less sufficient to ensure this latter function. ■ ■ ·

Thanks to this arrangement, despite the small diameter 'the Ball bearings get higher natural frequencies. .

It must also be ensured that the rotating part of the pump, both during the normal operating state, as well as during the start-up without play centered, due to the lack of any radial expansion of the bearing 19. The result is obtained thanks to the arrangement of the flange 1o in the form of a disk and in that it is at an axial distance from said bearing 19. Thus, the centrifugal pulling force has that in the plane the flange 1o acts, hardly any influence in the plane of the I ag he s 19, due to the elastic deformation of the intermediate cylindrical part of the ear piece 13 "

As far as the centering on the bearing 18 is concerned, it should be noted that the radial deformations of the reaming hole, which the Russian Diameter of the bearing, are negligible, since the cover piece 15, which is provided with the Aufnähmet) hole, full-walled is"

Finally, it must be noted that the rotating disks 1 are only crushed by the rods 7, which together make a hub crisper

909825/0378

BAD ORfSINAjL, ° '' ° '

Diameter "form, whereby it is possible, eie over the ^whole; Qutrbereich to distribute to and consequently jegliohes sliding zwieofcen the parts that no gleiohen deformations are subjected -to prevent addition, the Plansche 9 and 1o such can." Calculates be that no radial displacements between them and the Brehsoheiben 1 occur.

To the holes of the latter, the von.den rods 7 reached through not too much / at high speeds Subjecting it to radial forces is a certain amount of balance the masses through the thickenings 11 on the inner edge of the discs 1 q as well as through the thickenings 9a and 10a on the outer edge of the pool 9 and 1o made.

Din apparatus has so, as shown, at their outer, opposite sides on the one hand after 31 toward ^a:. ^ Rosnp τ "itöffnung, the adjoins the space to be evacuated, j on the other hand an outlet opening 32, to the SiOH a conventional vacuum pump (not shown) is connected, which is intended to create the upstream vacuum. Thus, the molecules move in the direction indicated by arrows, that is, from the suction to the outlet opening, on an axis in the direction of the axis of rotation X. * Y jewi Tomassen straight middle path. In particular, that of Bio Timmen forms on the suction side, i.e. on the side of the largest

ton Vphnjms, a remarkable advantage.

Such an arrangement reduces the pumping losses of b

knew

Do pre-call ?? en, which are caused by constricted ^ flow segments or ^ not "? jnj <**. flow paths are switched off.

909825/0378. _7th

BATHROOM ORIGINAL 1ο / ...

The modified Ausführvingsform according to FIG. 2 differs from the above-Taeschrietenen Ausftlhrungstieispiel mainly characterized DAAs its axis of rotation is vertical XY} angeordnei iiftct the passage ^r of the molecules in this main direction from top to bottom. -

In addition, the stack of turntables 1 by means of the rods 7 between the "two outer paddles 33 and 34 compressed These annular puddles that have a reinforced outer edge 33a and 34a, sit on two coaxial pipe sections 35 and 36. A small amount of play is left between the inner edge of the turntables 1 and the outer surface of the pipe sections 35 and 36, always with the aim of verifying local tightness in room B. avoid · The latter is by the way with the interior H of the Ptunpe through channels 37> which penetrate the splash 34, in connection "

The pipe section 35, which is closed by a floor 38 located at a higher level is, and the pipe section 36, which has no bottom at the front, are aligned one after the other by means of a central disk 39, those with (not shown) openings through which the inner spaces I and J of the two pipe sections are connected, is provided. These rooms are of; the space B lying outside the pipe pieces and the latter, in turn, from the outer, "below" vacuum

■ j '- -

Room P separated, j. _: .

In the central disc 39 comes from the sere end of the motor shaft j of the pump. This rotates in roller bearings'41 and 42, wel4

ι --- ■■■■ j

before sitting on a cylindrical, hollow shaft 43, which is inserted into a conical, over a surface 45 rigidly attached to the housing 5

909825/0378 11 / ...

BAOORiQfNAL

continuous foot 44 passes over. The hollow shaft 45 is arranged with the desired clearances between the shaft 40 and the tubular piece 36 and ends, of course, at an opposite the central disk 39, which connects the pump rotor with the said motor shaft forms, withdrawn point. This arrangement ensures that the rotating part of the bearings is inside and the fixed part is on the outside, which is regarding the very high rotational speeds and the mechanical stresses to which the pump is exposed are remarkable Advantage forms.

The upper bearing 41 is arranged in a plane that traverses the center of gravity of the entire rotating mass runs, or is in the immediate vicinity of this plane. It should thereby offer great radial rigidity and can be designed as a roller bearing, while the force acting in the axial direction, caused by the weight of the rotating mass the lower bearing 42 is received, which can be provided with an inclined bearing surface. The installation security in axial Direction is ensured by a stop 46, which only comes into action under completely exceptional circumstances, and if the upward forces coming from differential pressures are stronger than the weight of the engine, or if the imager 42 is destroyed «,

The pump is operated by an electric motor of some kind, ZoBo of some kind, which runs in an axial plane Has air gap and is provided with a winding plate with lamellar leads; this winding is formed by two discs 47 which are part of the stator of the motor and

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BATH

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and attached to the foot 44 of the Hohleohafteβ, while the beguiling 48 ι · Β _β consists of a ferromagnetic !! Bing magnet, which is fixed on a shaft 49, which rotates in bearings (not shown) carried by the stator of the motor

The shaft 49 is with the shaft 40 of the vacuum pump via a. . Coupled spline connection 50 that is capable of only one to transmit pure torque, and "regarding the position the eotor of the two door directions certain degrees of freedom allows · This connection also offers the possibility of disassembling one of the devices without affecting the other » Overall, the vacuum pump and the electrometer consist of two mutually independent devices, with the exception of the fact that the motor transmits pure torque to the pump.

At the end of the shaft 49 of the electric motor, a small auxiliary pump 51 can be provided for conveying the fluid, a centrifugal pump that sucks in through an axial line 52 leading from an oil pan 53 attached below the nozzle 44 and into a channel system 54 promotes to allow lubrication of the bearings · The return of the lubricant into the inner space K, which is kept under the pressure of the upstream vacuum via a pipe 55, into the oil pan 53, sent by gravity; the part of the lubricant which has penetrated into tree J is collected at the foot of the same and returned to the inner tree K through one or more suitable flow openings 58 , which surrounds the conical base 44 · This coating plays against oil vapors that arise and can get into the inner tree Ξ,. v- ^ ^: 9 ^ 9825/0378 BAD ORfÖfNAL _ ₁₃ "

the boll of a cooling jacket and prevents the fumes from a to achieve a remarkable pressure level · The (not shown) supply and discharge channels for the cooling water lead through the hem H and play the role of a «wide cooling stage that is superimposed on the previous one.

It should be noted by SSU that, as in the previous embodiment, as a result of the tight separation of the trees X, J, K ₉ may contain the oil particles, from the inner tree S and as a result of the tight separation of the latter from the tree towards 3? the bearings 4-1-4-2 and the lubrication system are completely separated from the vacuum side

The cooling of the electric motor, which as a result of it cannot take place by convection within the tree K under vacuum, takes place by cooling the stator 47 is provided by water circulation; on the other hand, the rotor 48, which consists of a ferromagnet, does not need to be cooled will·

The device described above is remarkably suitable for a desiccation process, which consists in to heat, in order to prevent the passage of gas into the Walls are included to support, without on the other hand running the risk of causing evaporation of the oil at where the fumes up in the tree? could get there and the container to be evacuated «.

This is ensured thanks to the general design of the pump »

a - rennet on the upper rope and circulation of the grass molecules in the outer rope of the! pump, oil tank in the inner part and

Lubrication zone in the center of this part}

9025/0378. _BAÖ ORIGINAL

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b- complete sealing of the trees, into which oil particles could get, from the vacuum space j

c- Cooling jacket, which prevents any oil vapors that may develop from reaching a considerable pressure level.

• One can accomplish the drying out according to ^; the invention take a resistance heater 57 to the aid, which is arranged around the housing 5 and covered with a (not shown th) asbestos coat, ie to a heater, which is preferably on the surface 31a on the suction side and in the areas towards the pump, where the Elimination of trapped gas molecules has a critical character, it is appropriate «The heat is transferred by conduction into the outer, fixed parts of the pump and by heat radiation to the rotor * The temperature that reaches the inner central part of the pump is relatively low, the cooling jacket 56 still greatly diminishes it. .

As the desiccation progresses, the whole thing is under the pressure of the upstream vacuum as a result of the action of the usual yakuumpump (not shown), which is always connected downstream of the outlet opening 52, whereby the evacuation of molecules loosened from the walls is ensured when the turbo-molecular -pump reduced, z L _sake: schwinäigkeit running to the parts ,, which is in ^_heated,: bogies -

- ■■■■ '■ - i

State, suspend any mechanical stress \. 90 982 5/0 3 7 &

BATH ORIGINAL

«· 15 · - ■

H28239

When the dehydration has ended, the Current to the resistance heater 57, lets the pump cool down and the electric motor 47-48 at full speed run until the desired vacuum is reached.

Like the embodiment described first, the modified form according to FIG. 2 permits extremely high rotational speeds. aohwindlgkeiten "to achieve, due to the great flexural rigidity, which is achieved by placing the bearing 41 near the center of gravity of the rotating part, wherein the second bearing 42 is only intended to record the moments around the center of gravity of the rotating part ι the Rigidity of the part of the hollow shaft 43 between the two bearings is sufficient to ensure the latter «

909825/0378

Claims (1)

DR. ING. H. SBGBNbAIiK '■ 1 H Z O Z O cJ EAHBtTBQ ae · NKtTBH WAlI, 41 »· PERNRU * 84 83B8 TJND 88« IB SISlBlFlIHt S ^ oiete Hati.onale d'Etfude et de Construction the Moteurs d'Aviation 15Q »Boulevard Haussmann \
P a ^ fe'M / Seine / France .. Claims \ Aj Turbömöiekular vacuum pump, consisting of a series of successive disks (i, 2), which are used for the passage? of gas molecules suitable openings (3, 4) ve ^ eh ^ 3 | are characterized in that the pump has a single direction of flow, the suction on the vacuum side through a large feed opening (31) located on one side of the disk set, while the discharge against the upstream vacuum takes place through an opening (32) takes place on the opposite side, whereby the molecules of the dilute gas have a central passage without any bi # gumg itall Üt direction of the axis of rotation (XY), Itiid that the rotor of the pump by means (18-19, 41-42 ), which exclude any lubrication bearing on the vacuum side. Pump according to claim 1, characterized in that the mechanical transmission of the forces originating from the rotor on the pump housing takes place completely on one and the same side of the pump, the opposite of the vacuum side Side, wherein the rotor is connected in such a way that it is in a self-supporting manner in the direction of the vacuum side stretch. 90982 5/037 8 BATH ORIGINAL H29239 3. Pump according to claim 1 or 2, characterized in that the rotor is arranged on a main bearing ( 19t 41) which is installed in the vicinity of the center of gravity of the rotor and which has great flexural strength with respect to radial loads. 4. Pump naoh claim 3 »characterized! That a second bearing (18, 42) assigned to the preceding one is arranged at a certain distance from the center of gravity of the rotor and absorb the moments around this point allowed « 5. Pump naoh one of the preceding claims, characterized daduroh that all turntables (i) on two flanges (9-10, 35-34) are attached, which are connected to each other * bound and arranged in such a way that the whole one great rigidity is given in the radial direction, but with a small relative displacement parallel to the Axis of rotation is made possible. 6. Pump naoh claim 5 »daduroh characterized that ' the splash (9, 33) on the vacuum seldom in front of the first turntable is located and consists of a circular, full-walled Part consists. 7 · pump NaOH to claim 5 or 6, daduroh in that the side facing away from the vacuum Plansch (1O) · fin / zwisohen position occupying the successive Dreheoheiben * 9.09825 / 0378 BAD UJ '' -A- H28239 ι -I, pump after. Claim 5, 6 or 7, characterized in that that the flanges are provided with a thickening (9a-10a, 33 & -34 &) arranged on their outer hand. 9. Pump according to one of claims 5-8, characterized in that that the turntables (i) are attached to the paddles by means of rods (7) which are regularly arranged around the axis of eotation (X-Y) of the pump are distributed and extend parallel to it, these rods being successive Turntables in the area of annular parts (6) of increased thickness and mutually parallel end faces reach through, in such a way that the disks lie tightly on top of one another by means of said parallel end faces can. 10. Pump according to claim 9, characterized in that a further annular part (11) of increased thickness in an area of smaller diameter of the turntables is arranged, the thickness of this latter inner Part is very little less than the thickness of the former "such that a little play remains between the inner successive annular parts. 11. PungB according to claim 3 or 4 »characterized in that that the main bearing is connected to the entire structure of the turntables (1) with the interposition of a drill bit (13, 36) is that on a flange (10, 34) on which said Structure is attached and the sioh. in one opposite the sown Iiager in the axial sighting offset plane is located, sitat. 909825/0378 BADORKSJNAt. "■■ Τ» ' -S, - 'H28239 ■ I 12. A pump according to claim 11, characterized in that the rotor is arranged ala-supporting part on a carrier part (17, 43) which is stationary relative to the rotating member fixed ",.., And with radial play which the turntables ψ surrounding the supporting pipe section (13, 36). 13. Pump naoh claim 12, characterized in that the fixed support part, which is hollow and of relatively large diameter, has an end pin (i7a) of smaller diameter on which the bearing of the fiotors is arranged . > ': ■ _; 14. Pum «e according to claim 12, characterized in that the hollow piece by a circular, full-walled lid piece (15, 39) is closed, which is attached to the pipe section and is located in front of the outermost find of the fixed support part. Pump according to one of the preceding claims, characterized in that the lubrication circuit and, more generally, the space (DQ, JK) where the lubricant particles can circulate, in an absolutely sealed manner from the zone (E ¹ ) which is under vacuum , is separated. (£, 16. Pump according to claim 15, characterized in that to it is provided with a vertical axis (X-Y), the CXD ¹ ^ suck through the large feed opening (31) from above _o takes place, while the lubricant is due to Φ ^ ν. -j Gravity collects below, at a central point (^) at a distance from the outer zone adjacent to the vacuum BATH (fa). 17. Pump according to claim 15 or 16, characterized in that that a coolant (56) is placed around the space (K) containing the lubricant to prevent the rising of To prevent oil vapors up to the vacuum side. 18. Pump according to claim 17 _f, characterized in that heating means (57) are attached to the outside of the pump in order to bring about a drying out of the pump to promote the excretion and removal of gas particles adsorbed by the walls. 19. Pump according to claim 18, characterized in that the heating means consists of an electrical resistance heater exist, which surrounds the housing (5) of the pump and to it preferably the suction flange (31a) of the pump is intended to serve, / and the areas adjoining it heat. 20. Pump according to one of the preceding claims, characterized in that the rotor is on bearings (41-42) is arranged, which have their rotating part inside and their fixed part outside. o 21. Pump according to claim 20, characterized in that oo the bearings between a central motor shaft (40) and ^ a hollow shaft (43) are arranged, which surrounds the latter _ω . there and is attached to the housing of the pump, this oo. Motor shaft protrudes beyond the end of the hollow shaft and in this area with the so-tor of the pump under intermediate BATH - ■ \ - U28239 circuit on its part the said hollow shaft
surrounding pipe section (36) is connected, 22. Pump according to claim 21, characterized in that it is driven by a built-in auxiliary motor (47-48) which is on the outermost, the end opposite the
Hollow shaft (43) offset, opposite part of the
acts on the central shaft (40), this motor being arranged within a tight casing (44) which sits on said hollow shaft. 23 «Pump according to claim 22, characterized in that the inside of the casing (44) with the help of a pipe (55) or other, similarly acting means under the influence
the upstream vacuum is brought, and cooling of the motor is provided by a liquid circulation. . 909825/0378