DE1948804A1 - Vacuum pump - Google Patents

Description

PATENT LAWYERS Dr. D. Thomsen H. Tiedtke Q. Bühiing

Oipl.-Chem. Dipl.-ing. Dipl.-Chem.

8000 MONKS 2

VAL 33

TELEPHONE 0811/226894

TELEGRAM ADDRESS: THOPATENT

Munich September 26, 1969 Case PS-lOt / T 3299

Precision Scientific Company, Chicago (USA)

. Vacuum pump

The invention relates to mechanical vacuum pumps and in particular to an improved multi-stage rotary oil-sealed Vacuum pump with inner wing.

Oil-sealed multi-stage vacuum pumps with rotating inner blades (Gaede) have long been known. This well-known multi-level High vacuum pumps have separate rotors for each pump stage and are relatively bulky and space-consuming. Since the Gas flow from stage to stage through a line or a If the duct takes place outside the pump, such constructions are not always satisfactory.

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It is therefore the object of the invention to provide a multi-stage oil-sealed To create a rotating vacuum pump with an inner wing, which only has a single hollow rotor for the gas flow of Used level to level.

There has also been a need for miniature high vacuum pumps for some time reduced size. By the invention. new structural design, these requirements were met and it is therefore another object of the invention to provide a miniature high vacuum pump of reduced size which can still generate a high negative pressure.

It is also an object of the invention to provide a miniature high vacuum pump to create the type described, in the case of reducing leakage losses around the shaft when entering the outlet an improved seal is used at the pump stage.

^ Furthermore, it is the aim of the invention to make an arrangement in which the various components of the pump are quickly and easily screwed together during the union can, at the same time creating the ability to easily remove the blades and rotor without completely dismantling the pump remove and replace.

The aforementioned objects of the invention are achieved by a mechanical rotating oil-sealed vacuum pump with inner wing solved by a pair of stators, which are arranged side by side with the interposition of a middle plate, and by a pair

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end plates located at opposite ends of the two stators, thereby forming a pair of pump chambers. The stators and the center plate each have a bore; a single hollow rotor is rotatably supported in the center plate and extends into the bore of each stator, each protruding end of the rotor being capable of slidably supporting at least one vane. The rotr is open at both ends and provides an axial channel through the stators and the center plate, which forms a gas flow from stage to stage. Inlet devices lead gas into the first pump chamber, while a first gas transfer device leads or guides gas from the first pump chamber into the axial channel of the rotor. A second gas transfer device guides the gas from the axial channel of the rotor to the second pump chamber, while an outlet device guides gas from the second pump chamber to the outside of the pump. The rotor is preferably seated at the end of a motor drive shaft which is rotatably mounted in the end plate next to the other pump chamber. , - (

The invention is illustrated below with reference to schematic drawings explained in more detail using several exemplary embodiments.

Fig. 1 shows a plan view and partially in section mechanical vacuum pump according to the invention;

Fig. 2 is a front view of this pump;

3 is a partial sectional view of FIG

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right side of this pump;

FIG. U is a sectional view taken along line f-1 in FIG Figure 3 shows the main casting of the pump;

Figure 5 is a sectional view taken along line 5-5 in Fig. 3 and shows the end plate of the exit stage;

6 is a sectional view taken along line 6-6 in Fig. 3 and shows the stator of the exit stage;

Figure 7 is a sectional view taken along line 7-7 of Figure 3 showing the center plate;

Fig. 8 is a sectional view taken along line 8-8 in Fig. 3 showing the entry stage stator;

Fig. 9 is a sectional view taken along line 9> 9 in

Fig. 3 and shows the end plate of the entrance step;

Fig. 10 is a front view of the rotor; Figure 11 is a sectional view taken along line 11-11

in Fig. 10;

Figure 12 is a sectional view taken along line 12-12

in Fig. 10;

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Fig. 13 is a view of the shaft;

Fig. 14 is a perspective view of one of the Pump blades;

15 shows the various elements of the pump in FIG

a diagrammatic exploded view. ·

The illustrated mechanical vacuum pump 20 is seated in accordance with FIGS. 2 and 3 on a base or base plate 22. The pump 20 has a main casting 24, which by means of a fastening screw 26 is attached to the base 22 (see Fig. 3). On the main casting 24, an outer housing 28 is attached, the one Limited cavity 30 in which the working elements of the pump 20 are arranged. In the space 30 is a supply of a sealing oil housed, the height of which is indicated in Fig. 3 by the reference character L and which covers the pump elements and seals. In the housing element 28, a transparent bubble 32 made of plexiglass or the like can be provided at a suitable location so that the oil level in the room 20 is observed visually can be,

The main casting 24 is traversing this with a Central opening 34 is provided and also has a recess 36. The recess 36 is by means of a in the end face ■,, of the main casting 24 provided groove 38 with the oil bath in the room 30 connected. As will be explained in more detail later, deepening

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Fung 36 and groove 38 arranged so that around the point where the Shaft passes through the interior of the pump stages, an oil seal is achieved.

As can best be seen from FIGS. 1, 3 and 4, the main casting 24 is provided with four vertical holes on its upper side. The first hole is an entry hole 40 which is connected to an entry recess or cavity 42 in the casting 24. In the cast part 24 there is arranged an entry quay 44 (see FIG. 4) which traverses it and which is connected to the cavity 42 . ■

The second vertical hole in the casting 24 is. a hole 46 (see Fig. 3) into which a plug 48 is inserted. The hole 46 provides access for the supply of seal oil to the interior of the pump.

The third vertical hole provided in the casting 24 is a hole 50 into which a ballast valve 51 is screwed for a purpose to be explained later. The hole 50 is connected to a channel 52, which extends downward toward the interior of the pump and whose bottom portion having a transverse opening 54 (see Fig. 4) is connected, the purpose of later than 'will be explained ter.

The fourth vertical hole of the casting 24 is an outlet opening "56, which is connected to the cavity 58 in the casting 24 which in turn is connected to the cavity 30.

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In the inlet opening 40 and the outlet opening 56 can a pair of couplings or connectors 60, 62 screwed in be used as connection points for the pump in that of this operated system serve.

On the main casting 24 sits an electric motor 64 through which a motor shaft 66 (see in particular FIGS. 3 and 13) is driven. The shaft tJ6 is rotatably seated in a bushing 68 which is press fit seated in hole 34 of casting 24; the shaft 66 goes through the recess 36 through into the cavity 30 and is later closed Descriptively connected to the pump stages in terms of drive.

The stages of the pump are shown in FIGS. 1, 3 and 15 to the Main casting 24 bolted on. The pump stages are from an exit stage end plate 70, an exit stage stator 72, a center plate 74, an entrance stage stator 76, and an entrance stage end plate 78 formed. Each of these elements is shown in greater detail in FIGS.

As best seen in Figure 5, the exit has step end plate 70 is a generally circular disc that has a flattened bottom portion 80. In plate 70 a number of openings and depressions or cavities are provided, the function of which will become clear later. It is further a centrally located hole 82 is provided through which the front end shaft 66 passes therethrough. As explained later, is a pair of first mounting holes 84 and a second set

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of mounting holes 86 provided. In the end plate 70 (the as explained later 'with respect to the other elements the pump is slightly oversized) is another pair of mounting holes 88 which are countersunk to form seats for a pair of bolts 90 (see Fig. 1) which are used for the Attaching the end plate 70 to the main casting. 24 (see in particular Fig. 1) serve. In the upper portion of the end plate 70 are a pair of for a purpose to be explained later vertical bores 92 are provided.

A transverse entry hole 94 is arranged in the end plate 70, that with the end plate 70 mounted on the main casting 24 is aligned with the channel 44 in the casting 24, which in turn is connected to the inlet cavity 42 in the main casting 24.

In the end face facing away from the main casting 24 End plate 70 is provided with a pair of recesses, i.e., a generally U-shaped exit step entry recess and a generally L-shaped exit step exit recess 98. As will be described in detail later, the Recess 96 for the passage of gas from the hollow interior of the pump rotor to the pump chamber of the outlet stage, while the recess 98 for the passage of gas from the pump chamber the outlet stage to the outlet of the pump .20 is used. In the plate 70 a transverse hole 99 (see Fig. 5) is arranged, the establishes fluid communication between recess 98 and gas ballast port 54.

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The exit stage stator 72 is generally disc-shaped 'and has a central hole used for the delimitation of an exit stage pumping chamber 100 serves. The stator 72 has a first set of holes 102 corresponding to the first pair of holes 84 in the end plate 70 corresponds; The stator also has a second set of mounting holes 104 that match the holes 86 in the end plate correspond; Furthermore, the stator 72 has a transverse hole 106, which as Part of the gas inlet channel connects to the opening 94 in the end plate 70 "; similarly, a transverse jj Hole 108 is provided which is connected to the L-shaped recess 98 in the end plate 70 and thus part of the outlet channel the pump 20 forms.

As best seen in Figures 3, 7 and 15, the center plate 74 has a generally disc-shaped portion with a flattened surface 120 on the head portion. The middle plate 74 has a hole 122 in its center. In the middle plate 74 there is provided an entry hole 124 which traverses it and which is connected to a hole 106 in the outlet stator 72. An outlet channel 126 partially extends transversely through the plate 74 and is connected to a vertical outlet opening 128 arranged in the flattened section 120. The center plate 74 has a first pair of mounting holes 130 and a second set of mounting holes 132. The holes 130, 132 can be aligned with the holes 102, 104 in the exit stator 72. In addition, each of the holes 130, 132 is provided with a radial bore 131 j 133 for a purpose to be explained later.

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The entry stage stator 76 (see in particular Fig. 1, 8 and 15) is essentially identical to exit stage stator 72. It has a generally disc-shaped part a central hole defining an entry stage pump chamber 140. A first set of countersunk mounting holes 142 are provided in stator 76, mating with holes 130 in the center plate 74 can be brought into alignment. Similarly, a second set of mounting holes 144 are provided, coinciding with the holes 132 can be brought into alignment in the center plate 74. An entry hole 146 extends transversely through the entry stator 76 and is in gas communication with that in the center plate 74 provided entry hole 124 produces.

The entry step end plate 78 has a disk-shaped part with a series of mounting holes 150 which can be brought into alignment with the holes 144 in the stator 76. A pair of depressions 152, 154 are arranged on the inner face of the end plate 78. The recess 152 serves as an entry stage entry recess and provides communication between the pump chamber 140 and the entry hole 146 in the entry stator. The recess 154 provides a gas guide between the pump chamber 140 and the hollow center of the step. The end plate 78 does not have a central hole through which the shaft extends or is supported in the same.

In the large center holes in the entry stator 76, the A single hollow rotor 160 is arranged in the middle plate 74 and in the outlet stator 72 as shown in FIGS. 10 to 12. The through

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194880 Α .. - left -

diameter of the rotor 160 corresponds essentially to the diameter of the hole 122 in the center plate 74 so that the rotor 160 runs sealingly in this hole. As best seen in Figures 11 and 12, rotor 160 is as discussed below an annular groove 162 is provided. An axial hole is located in the center of the rotor 160 around a rotor cavity 164, with the entrance step portion 166 having a somewhat reduced diameter. The ends 170, 172 of the rotor cavity 164 are chamfered outwards to allow gas communication between the rotor cavity and the recesses 96 and 154 in the end plates 70, 78.

A transverse bore 174 extends through the center of the rotor 160 which provides fluid communication between the rotor cavity 164 and the annular groove JB2, as will be explained later will. In the exit stage side of the rotor 160 are a pair of radial grooves 176 for receiving a locking pin s intended * the one for locking the rotor on the shaft can be passed through the shaft 66. In the rotor 160 are vane slots 180 on the outlet side and on the inlet side Wing slots 182 disposed; When the rotor 160 revolves, a wing 184 slides in its wing slot forwards and forwards back, the wing being pressed outward under centrifugal force, so that its outer end, which according to FIG. 14 is rounded is, with the stator (see Fig. 8) remains in constant contact.

As best seen in Figures 3 and 13, has the shaft 66 has an enlarged diameter portion, the one

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■ - 12 -

Has flattened surface 190 that is rotatable with the motor shaft 64 can be connected. The shaft 66 has a section 192 of reduced diameter, which rotatably extends through the socket 68 in the main casting 21 (see Figure 3). Also owns the shaft 66 has an elongated portion of reduced diameter 194, which is provided with an annular groove 196, where near a transverse bore at the end of the reduced diameter section 194 .198 is arranged. The shaft portion 194 extends through the hole 82 in the outlet step end plate 70.-In hole 198 is an interference fit locking pin 200 (see Fig. 3) fitted, the ends of locking slots 176 and rotor 160 are incorporated into a drive connection between the rotor 160 and the shaft 66 to establish. The 'wave section 19li only extends through the outlet end plate 70 and also only in the exit stage, but not through this still through or into the entry level. The entry endplate 78 has no holes, openings or other connections with the interior of the pump, so that leakage from non-P degassed oil can be avoided in the entry stage.

In the recess 36 of the main casting 24 is an oil bath pre ' seen to achieve an oil seal around the location where shaft 66 passes through end plate 70. To the passage of oil from the hub 36 along the reduced diameter shaft section 194 into the rotor cavity 164 is minimized To reduce, a circumferential graphite ring seal is arranged according to FIG. 3 around the shaft 66. In a recess in the end plate = 70 a part 202 is arranged, which has an O-ring seal in a groove

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device 204 carries. A graphite ring 206 is arranged around the shaft section 19t, a cap 208 partially surrounding the ring 206 being pressed by a spring 210 against the ring 206, which in turn is pressed against the surface of the bearing 202. A rubber sleeve 211 prevents oil leakage along the shaft, the sleeve 211, the spring 210, the cap 208, the graphite ring 206 and the shaft 66 rotating as a unit relative to the part 202. To seal the oil bath in recess 36 against the shaft 66 as it passes through the hole 34 in the cast part 24, a similar circumferential graphite ring seal 212 with identical parts is provided. By using the double graphite ring seal, the oil passage from the '\ exfcLefurg - .36 along the shaft and through the end plate 70 into the interior of the pump stage is completely prevented.

The unique design of the invention obviates the need for end caps that cover the places where the Shaft passes through the end plates of the pump stages while on the other hand, such caps are necessary in the known pumps. In the invention, the wave does not even go through the entry endplate therethrough; Also, since a shaft seal is used, no end cap is required on the exit stage end plate required, which seals the point of the shaft passage through this end plate from the surrounding oil bath.

As is known, it is desirable that a controlled small amount Ul is regularly introduced into the interior of a umlau f ending high vacuum pump of this type to be on the surfaces in the

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Inside the pump to seal the various moving Parts to form an oil film. In the case of the pump 20 according to the invention this is controlled oil supply with the help of a "leak" valve plate 220 (see FIG. 1), which is clamped with the aid of a bolt 222 via the outlet opening 128. The Ven · » The valve plate 220 has an elongated slot 224 which extends over the opening 128 and which allows leakage oil to enter in a controlled manner into opening 128. A valve of this type is in ^ detailed in U.S. Patent 3,326,456.

The various operating parts of the pump can be combined in the following manner. If the motor 64 and the main casting 24 are in the correct position of the shaft 66 with the associated sealing arrangements of the shaft on the base 22, the exit plate 70 is attached to the main casting 24 via the holes 58. The exit stage stator 72, the center plate 74 and the entry stage stator 76 are brought together in alignment and a pair of bolts 230 are inserted through the aligned P hole pairs 142, 130 and 102 and the aligned holes 84 in the end plate 70 and in the main casting 24 so that these Elements can be set in precise alignment. The rotor 160 is then pushed onto the shaft 66 so that the pin 200 engages in the locking grooves 176. How to .besten at _f in Figs. 6 and 8 ersieht, the holes in the stators 72, 76 are greater than those in the center plate 74 and also larger than the diameter of the rotor 160. Thus, the rotor is located opposite the holes in the Stators 72, 76 eccentric. Thus, the rotor and the pump chambers 100, 140 form crescent-shaped pump chambers "those carried by the rotor 10"

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Wings 18t are traversed during rotation.

There will then be a fine adjustment of the alignment of the various Parts brought about and finally the bolts 230 dressed. The entry step end plate 78 is then attached, after which the elements are tightened with a series of bolts 250 which pass through the aligned hole sets 150, 144, 132, 104 and 86 extend into a corresponding number of aligned threaded holes 260 in the casting 24. The top cover can be attached to the end plate of the outlet valve end point P, a splash guard 270 is attached will.

After assembling the pump and after introducing oil through it the hole 46 up to the level L, at which the entire pump is submerged and the space 30 and the recess 36 are filled with oil, the pump works in the following way. In Fig. 15, which is an exploded view of the pump according to the invention. shows a number of arrows are indicated to guide the gas flow through to show the pump; the gas emerges from the area to be evacuated via the connection 62, the inlet opening 40, the inlet cavity 42 and through channel 44 and thence through the series of aligned inlet holes 94, 106, 124 and 146 of the outlet end plate, the exit stator, center plate, and entry stator and finally through the entry recess 152 in the end plate 78 into the pump, whereby it arrives in the inlet recess 152 in the pump chamber 140 of the inlet stage.

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The gas is circulated by a vane 184 carried by the rotor 160, compressed, and through the entry stage exit cavity 154 of the end plate 78 is pushed outward, wherein the gas enters the rotor cavity 164. The gas is from the Entry stage through the exit stage to the exit stage entry cavity 96 of the end plate 70 transferred to the upper guide of the gas from the rotor cavity 164 to the pump chamber 100 of the outlet stage, in which it is again lifted through vanes 184 ^ swirled around and through the exit stage exit cavity .98 is pushed outwards. The aligned hole 108 in the exit stator 72 and the hole 126 in the center plate provide the Outlet channel, with an outlet valve plate 220 above the outlet opening 128 of the central plate 74 as described above on the head end of the middle plate 74. Pass gas is thus forced out through the valve plate 220, in which it is in Bubble shape comes to the surface of the oil level L and then through the hole 56 in the outlet connection 60 to the outside.

W As already mentioned, the pump is lubricated by controlled delivery of small quantities of oil into the outlet opening 128, by retaining the PEP rearwardly into the interior of the pump, WO 'by the surfaces of the pump with a thin oil film is moistened and thereby, be sealed. An Ouerbore 174 is provided in the rotor 160, which forms a connection between the groove 162 and the rotor cavity 164. This groove serves to ensure that the oil in the groove 162 migrates along the outer surface of the rotor 164 from the outlet stage pump chamber 100 in the direction of the inlet stage pump chamber 140 for degassing.

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By merely removing the bolts 250, the entry step end plate can be removed without the other attached elements must be removed so that the rotor can easily be pulled out and the blades can be replaced.

Furthermore, according to the invention, the two-stage pump is used for both stages a single rotor used. With regard to the unique cantilevered arrangement of the rotor at the end of the line and In view of the very loose connection between the shaft and the rotor, it is not necessary to place the motor shaft in the operating parts perfectly aligned with the pump. Instead, the rotor itself is precisely located in the center plate aligned, with the independently slidable vanes for completing the alignment in the stators the pump. Furthermore, since the shaft does not pass through the entrance step end plate 78 extends, the possibility of oil passage from the space 30 with trapped gas into the inlet s level is reduced to a minimum, which results in an improvement in the efficiency of the pump. In addition, is prevents oil from the bath reduced along the shaft section ver Diameter 1 ^ 4 enters the pump, for which the fdouble Graphite ring seal is used. Oil only enters the pump through the check valve 220, in which it is degassed, with oil that is between the rotor 164 and the hole 122 of the center plate wanders, through the grooves 162, 17 ^ is also degassed,

so that Ul fully reaching the inlet stage of the pump is degassed.

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By proper adjustment of the gas ballast valve 51 can via the hole 50 the channel 52, the opening 5 ¹ ', the hole 99 and the cavity 98 occur skanal atmospheric air in small quantities in the pump outlet.

The invention thus provides a unique very effective rotary oil-sealed mechanical two-stage vacuum pump, thanks to the new arrangement of its elements in a very small size Execution can deliver an extremely effective high vacuum pump.

Thus, it has an improved multi-stage mechanical vacuum pump with oil seal and inner wing one through each stage of the Pump going rotor, which is provided with the respective blade sets for each stage. The only rotor has an axial hole, which crosses the rotor and serves for the gas line from stage to stage,

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Claims (12)

Claims . Multi-stage mechanical vacuum pump, characterized by a pair of stators (72,76) which are arranged next to one another with the interposition of a central plate (74), by a pair of end plates ^ (70,78) arranged at the opposite ends of the stators, whereby a first pump chamber ( IfO) and a second pump chamber (100) is bounded by a single hollow rotor (160) rotatably mounted in the center plate and protruding into each stator, each protruding end of the rotor slidably receiving at least one vane (184) wherein the rotor is open at both ends and thereby an axial channel C164) forms by the stators and the central plate ¹ for guiding a gas from stage to stage. 2. Vacuum pump according to claim 1, characterized by inlet devices (62,40,42,44,94,106,124,146,152) for directing gas into the first pump chamber (140) through a first gas transfer device (154) for directing gas from the first pump chamber (140) into the axial channel (164) of the rotor, through a second gas transfer device (96) for the conduction of gas from the axial channel of the rotor into the second pump chamber (100) and through an outlet device C98) for the passage of 009827/1145 Gas from the second pump chamber to the outside of the pump. 3. Vacuum pump according to claim 1 or 2, characterized by an annular degassing groove (162) provided in the outer peripheral surface of the rotor (160) and at least one between this groove and the hollow interior of the .Rotors provided radial channel (174). 4. Vacuum pump according to claim 1 to 3, characterized marked ^ ch- ™ net that the rotor is seated at the end of a shaft (66) which. rotatable preferably in the one next to the second pump chamber (100) End plate (70) is mounted. 5. Vacuum pump according to claim 1 to 4, characterized by a closure device (24,28) which the end plate (70,78), the Stators (72,76) and the middle plate (74) encloses and one Forms cavity (30) for receiving an oil bath in which the end plates, stators and the middle plate are immersed, 6. Vacuum pump according to claim 5, characterized in that a spring-loaded graphite shaft seal (202,204,206) is provided at the point of the shaft (66) at which it passes through the end plate _{Ä (70).} 7. Vacuum pump according to claim 5 or 6, characterized in that that the closure device has a main support part (24) and a housing part (28), the housing part in such a way on the Main support part is attached that it is the end plates, the stdoren 0-09827 / 1US and surrounds the center plate. 8. Vacuum pump according to claim.7, characterized in that the end plate (70) lying next to the second pump chamber (100), the stators (72, 76) and the middle plate (74) as a unit are attached to the main support body (24), the end plate (78) adjacent to the first pump chamber (140) preferably being independent and is releasably attached so that the interior of the pump chamber is accessible. 9. Vacuum pump according to claim 5 to 8, characterized in that that the shaft (66) is rotatably mounted in the main support body (24), and at the point where the shaft through the main support body occurs, a spring-loaded graphite shaft seal (212) is arranged. 10. Vacuum pump according to claim 1 to 9, characterized in that that the entry means has a first channel (152) in the end plate (78) located next to the first pump chamber (140) and a transverse channel (94,106,124,146) in the stators (76,72), the middle plate (74) and the end plate (70) lying next to the second pump chamber (100), that the first gas transfer device a second channel (154) in the end plate (7-8) lying next to the first pump chamber (140) that the second gas transfer device has a first channel (96) in the end plate (70) adjacent to the second pump chamber (100) and that the outlet device (98) has a second channel in the next the second pump chamber (100) lying end plate (70), a ! Transverse channel (126,108λ in the middle plate C74) and the second 009 8 2 7 / 1U5 19488 0A The stator (72) forming the pump chamber and an outlet opening (128) in the middle plate. 11. Vacuum pump according to claim 1O _4, characterized by an outlet valve (220) which is assigned to the outlet opening (128) of the central plate (7 ¹ O and which allows for the expulsion of gas from the outlet opening and the passage of a controlled amount of lubricating oil from the oil bath in the exit opening is permitted. ■ --.- ■ 12. Vacuum pump according to claim 1 to 11, characterized through a gas ballast outlet duct (52) connected to the outlet device and through an adjustable gas ballast valve (51) which is connected to the gas ballast duct and the controlled supply of atmospheric air to the pump allowed. 009827/1145