KR20220127266A - dry vacuum pump - Google Patents

Abstract

A dry vacuum pump (1), wherein at least two pumping stages (1a to 1f) have an inlet (7) and an outlet (8) emerging from respective half shells (9, 10) respectively, and the stator (2) is a combined halve It further has a stator casing 15 surrounding the shells 9 and 10, and on the outer surface of the stator casing 15 or the half shells 9, 10, the stator casing 15 is coupled to the half shells 9, 10 at least one groove 20 is provided so as to form at least one conveying channel 21 by A dry vacuum pump is provided which is arranged in communication with the inlet 7 of 1b to 1f).

Description

dry vacuum pump

The present invention relates to a dry vacuum pump, specifically to a multistage dry vacuum pump such as a roots type or claw type pump.

The multi-stage vacuum pump has a plurality of pumping stages mounted in series, and a pumping target gas circulates between the suction unit and the discharge unit at the plurality of pumping stages. Among the known low vacuum pumps, a distinction is made between rotating-lobe pumps, also known as “roots” pumps, which have two or three lobes, and double-claw pumps, also known as “claw” pumps.

A dry vacuum pump includes two rotors having the same profile and rotating in opposite directions inside a stator. During rotation, the gas to be pumped is trapped in the volume formed by the rotor and the stator, moved to the next stage by the rotor, and then progressively progresses until the vacuum pump is transferred.

The continuous pumping stages are connected in series with each other by a conveying channel connecting the outlet of the preceding pumping stage and the inlet of the subsequent pumping stage. These conveying channels are generally integrated into the stator. The conveying channel is provided in a wall interposed between the compression chambers, or is arranged on either side of the compression chamber.

Moreover, in order to further facilitate the machining and assembly of the multistage vacuum pump, the stator consists of two half shells that are sometimes joined in a longitudinal engagement plane substantially parallel to the axis of the rotor, for example as described in patent document US6572351. . The stator formed as a half shell makes it possible to use an integral shaft-rotor. In this case, the assembly time can be reduced because the number of interfaces to be aligned is small. This architecture may also reduce the risk of accumulating alignment defects.

A drawback of this embodiment is that it is difficult to achieve a good seal between the half shells. Specifically, the compression chamber and the conveying channel integrated in the stator are in two parts, a first part is provided in the first half shell, and a second part is provided in the second half shell. This entails the need to seal these two parts to each other at the longitudinal mating plane.

One solution consists in gluing the half shells together through a curable seal. However, the material of the curable seal may be insufficiently resistant to corrosive gases, particularly in certain applications.

Another solution consists in using a three-dimensional seal which implements a seal between the exterior and the pumping stages and between the exterior and the conveying channel. However, such seals may incur additional meaningless costs due to the additional need to be coated with an equally expensive corrosion-resistant material, especially with complex shapes that are costly to manufacture.

Another drawback to manufacturing half shells with conveying channels integrated into the stator is that the inside of the channels is difficult to access, thereby complicating both the cleaning in the manufacturing and maintenance steps of the half shells.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a multistage dry vacuum pump which at least in part solves any one of the above-mentioned drawbacks.

To this end, the subject of the present invention is a dry vacuum pump, comprising:

- a stator having two complementary half shells meeting at the mating face and forming at least two pumping stages mounted in series between the intake and discharge portions of the vacuum pump;

A dry vacuum pump comprising two rotor shafts configured to synchronously rotate in opposite directions at a pumping end to move a gas to be pumped between an intake portion and an exhaust portion,

- at least two pumping stages each having an inlet and an outlet emerging from separate half shells;

- the stator further has a stator casing surrounding the joined half shell, the outer surface of the stator casing or half shell being provided with at least one groove to form at least one conveying channel by coupling the stator casing to the half shell, at least One conveying channel is a dry vacuum pump characterized in that an outlet of a pumping stage is arranged in communication with an inlet of a subsequent pumping stage.

Accordingly, the at least one conveying channel extends in the stator, at the side of the pumping end and outside the half shell. The inner side of the conveying channel is thus accessible when the stator casing is removed from the half shell. The conveying channel is thus easily accessed when the vacuum pump is disassembled, thereby facilitating manufacturing and cleaning. The conveying channel is moreover integral, thus making it possible to avoid the need to seal the conveying channel at the mating surface.

The vacuum pump may also have one or more of the features described below, considered by itself or in combination.

The outlet of the pumping stage may be arranged to communicate with the inlet of the subsequent pumping stage by means of two conveying channels, each arranged on one side of the pumping stage.

The stator casing may have an overall elliptical or cylindrical cross-section.

At least one groove may have a helical portion. Due to the spiral shape, the outlet of the pumping end can be arranged to communicate with the inlet of the subsequent pumping end smoothly without sharp angles. Since there is no abrupt change in the conveying channel, it is possible to limit the pressure drop, thereby avoiding an increase in power consumed and heating of the pumped gas and vacuum pump. By controlling the pressure drop in the conveying channel, the formation of a dead zone leading to the accumulation of condensable objects can be avoided and, if appropriate, it is made easier to convey the powder together.

The two spiral-shaped portions of the two conveying channels may be connected to each other by first and second straight portions of the conveying channels, the first straight portion communicating with the inlet and the second straight portion communicating with the outlet.

The inlet of the pumping stage may be provided on a first flat surface of the first half shell, and the outlet may be provided on a second flat surface of the second half shell, the first and second flat surfaces being parallel to each other.

The stator may have first and second end plates coupled to an axial end of the stator casing, the vacuum pump comprising at least one first annular seal interposed between the stator casing and the first end plate; and at least one second annular seal interposed between the two end plates. The annular seal is thus compressed between the flat surface and the fixed surface positioned opposite to each other. As a result, such a seal can be a conventional annular seal, ie a flat O-ring seal, and thus can be made with a simple technique, resulting in low cost.

A discharge channel communicating between the last pumping end and the discharge unit may be provided in an end flange of the stator, and the end flange is coupled to the first end plate of the stator.

According to a first example, the vacuum pump has no seals in one part between the half shells and in another part between the half shells and the stator casing. In this case, neither a flat or three-dimensional O-ring seal nor a hardenable seal is provided between the half shells and between the half shell and the stator casing. The seal between the pumping stages is ensured by the half shells being fastened together. The seal between the conveying channels is realized by a precise fitting of the stator housing onto the half shell. This is made possible in particular by the fact that the stator casing may contain any gas leakage from the pumping stage or the conveying channel. The seal between the pumped gas and the outside of the vacuum pump may be implemented by using at least two conventional annular seals disposed on the two axial ends of the stator casing.

According to a second example, the vacuum pump has at least one annular seal interposed in one part between the half shell and the stator casing and in another part between two successive pumping stages.

When the at least one groove is provided with the stator casing, the vacuum pump may have at least one bypass channel inserted between the two inlets or between the inlet and the outlet, the at least one bypass channel being provided in the stator casing, the bypass In the channel, a valve is arranged to open and close the bypass channel according to the pressure difference on both sides of the valve.

When the at least one groove is provided in the stator casing, at least one fluid circulation channel may be provided in the stator casing to thermally exercise the stator or to distribute the fluid to the pumping stage.

When the at least one groove is provided in the outer surface of the half shell, the stator may have a further stator casing surrounding the stator casing, and the vacuum pump is configured to allow a fluid to pass between the stator casing and the further stator casing to thermally move the stator. It is configured to circulate the gap in which it is located.

The mating surface of the half shell may pass through an intermediate surface of the vacuum pump, such as a plane containing the axis of the rotor shaft.

Other advantages and features will become apparent from a study of the accompanying drawings and also the following description of one particular, non-limiting embodiment of the present invention.
1 is a perspective view of a pumping part of a dry vacuum pump according to a first embodiment.
FIG. 2 is a cross-sectional view of the pumping portion of the vacuum pump of FIG. 1 in a vertical intermediate plane passing between the rotor shafts; FIG.
3 is a perspective view of a half shell coupled with the rotor shaft of the vacuum pump of FIG. 1 ;
Fig. 4a is a view showing the upper half shell of the stator of Fig. 3;
Fig. 4b is a view showing the lower half shell of the stator of Fig. 3;
FIG. 5 is a view giving the stator casing, end flanges and end plates of the stator in the vacuum pump of FIG. 1 ;
FIG. 6 is a view showing the longitudinal and vertical ends of the stator casing of FIG. 5 ;
FIG. 7 is a view of two conveying channels of the vacuum pump of FIG. 1 , arranging the outlet of the pumping stage in communication with the inlet of a subsequent pumping stage; FIG.
8 is an exploded view of a modified example of the pumping part.
Fig. 9 is a schematic side view of a pumping part of a dry vacuum pump according to a second embodiment, seen in a longitudinal section of the stator casing;
FIG. 10 is a schematic cross-sectional view of the pumping part of FIG. 9 ;
Fig. 11 is a schematic bottom view of the pumping part of Fig. 9, seen in a longitudinal section of the stator casing;
Fig. 12 shows a view similar to Fig. 10 in a modified example.
In these drawings, identical or similar elements have the same reference numerals.
The drawings have been simplified for clarity. Only elements necessary for an understanding of the invention are shown.

The examples below are examples. Although the description refers to more than one embodiment, this does not necessarily mean that each reference is to the same embodiment or that a feature applies only to one embodiment. Individual features of different embodiments may be combined or interchanged to provide other embodiments.

The longitudinal direction is defined as the direction in which the axis of the rotor shaft extends.

1 and 2 show at least two pumping stages 1a to 1f, for example 2 to 10 pumping stages, in this case in a line between the intake part 3 and the discharge part 4 of the vacuum pump 1 . A first exemplary embodiment of a multi-stage dry vacuum pump 1 having a stator 2 (or pump body) forming six pumping stages 1a to 1f mounted with

The pumping stage 1a communicating with the intake part 3 of the vacuum pump 1 is the first pumping stage or the pumping stage having the lowest pressure, and the pumping stage 1f communicating with the discharge part 4 is the last pumping stage. or the pumping stage with the highest pressure.

The vacuum pump 1 has two rotor shafts 5 configured to synchronously rotate in opposite directions at pumping stages 1a to 1f to move the pumping target gas between the intake portion 3 and the discharge portion 4, 6) (FIGS. 2 and 3) also have.

The shaft may be, for example, a rotor having lobes with the same profile, such as a “roots” type or “claw” type or other similar positive displacement vacuum with two lobes ( FIG. 8 ), three lobes ( FIG. 3 ) or more lobes. It supports the rotor based on the pump principle.

These rotor shafts 5 , 6 are advantageously one-piece.

The stator 2 has two complementary half shells 9 , 10 which meet at the mating surface 11 and form at least two pumping stages 1a to 1f . The engaging surface 11 of the half shells 9 , 10 can pass through an intermediate surface of the vacuum pump 1 , such as a plane comprising the axis of the rotor shaft 5 , 6 . The mating surface 11 is, for example, substantially flat or has a complementary shape between the half shells.

Each pumping stage 1a to 1f defines a compression chamber of the stator 2 which houses the two mating rotors of the vacuum pump 1 . The at least two pumping stages 1a to 1f each have an inlet 7 and an outlet 8 emerging from separate half shells 9 , 10 .

During rotation, the gas drawn through the inlet 7 is entrapped in the volume formed by the rotor and stator 2 of the pumping stages 1a to 1f, and then compressed, towards the outlet 8 and towards the next end. is moved

The pumping stages 1a to 1f have a swept volume, ie the volume of pumped gas, which decreases (or remains the same) with the pumping stages 1a to 1f, and the first pumping Stage 1a has the maximum swept volumetric output and the last pumping stage has the minimum swept volumetric output. The axial dimension of the rotor is, for example, equal to or decreases with the pumping end, the pumping end 1a being placed on the side of the intake 3 receiving the rotor of the largest axial dimension.

In operation, the rotor shafts 5 and 6 are rotationally driven by a drive unit (not shown) comprising a motor driving the rotor, a gear synchronizing the rotor, and a bearing supporting the shaft of the rotor. The motor of the vacuum pump 1 is mounted on either one of the shafts 5 , 6 , for example at one end of the vacuum pump 1 , such as on the discharge part 4 side of the vacuum pump 1 . The vacuum pump 1 is called “dry” because in operation the rotors 5 and 6 rotate inside the stator 2 with a very small clearance without mechanical contact between the rotors or with the stator 2 . Because of this, there is no need to provide oil to the compression chamber.

The joined half shells 9 , 10 have, for example, an elliptical cross-section ( FIGS. 3 , 4a , 4b ). The inlet 7 of the pumping stage is provided in a first flat surface 12 of the first half shell 9 , for example the upper half shell. An outlet 8 is provided, for example, on a second flat surface 13 of the second half shell 10 , such as the lower half shell, with the exception of the outlet 8 at the last pumping stage 1f. The first flat surface 12 and the second flat surface 13 are parallel to each other.

The inlet 7 and the outlet 80 have, for example, an elliptical cross section, with the exception of the last pumping stage 1f. The inlet 7 and outlet 8 of the first pumping stage 1a have, for example, a maximum cross-section.

The half shells 9 , 10 are fastened to each other, for example by means of two rows of screws, which are regularly screwed into holes 14 provided in the half shells 9 , 10 on each side of the mating surface 11 .

The stator 2 also has a stator casing 15 surrounding the joined half shells 9 , 10 . The stator casing 15 is complementary to the half shells 9 , 10 .

The stator 2 may also have first and second end plates 16 , 17 coupled to the axial ends of the stator casing 15 , for example by means of screws. The end plates thus extend perpendicular to the longitudinal direction of the rotor shafts 5 , 6 .

Likewise, the stator 2 may have an end flange 18 bearing lubricant sealing means, for example inserted between a drive (not shown) and a dry pumping part in the shaft passage. The end flange 18 has a flat face that is fastened to the first end plate 16 , for example by means of screws. The shaft passage is, of course, provided in the compression chamber of the pumping stage through which the end plates 16 , 17 and the rotor shafts 5 , 6 pass.

According to an exemplary embodiment, the outlet 8 of the last pumping end 1f is not exposed on the flat surface of the lower half shell 10, but is provided on an end flange 18, which communicates with the outlet 4, It communicates with the discharge channel 19 (FIG. 2). Due to this configuration, it is possible to more easily manufacture a discharge portion having an orifice of a standard diameter, which is usually used in the field of vacuum technology.

According to a first exemplary embodiment of the present invention, at least one groove 20 is formed in the stator to form at least one conveying channel 21 by coupling the stator casing 15 to the half shells 9 , 10 . It is provided in the casing 15 (FIG. 5). At least one conveying channel 21 is arranged such that the outlet 8 of the pumping stages 1a to 1e communicates with the inlet 7 of the subsequent pumping stages 1b to 1f. Accordingly, the at least one conveying channel 21 extends within the stator 2 , on the side of the pumping stages 1a to 1f , on the outside of the half shells 9 , 10 and on the inside of the stator casing 15 . do. The inside of the conveying channel 21 is thus accessible from the inside of the stator casing 15 when the stator casing 15 is removed from the half shells 9 , 10 . The conveying channel 21 is thus easily accessible when the vacuum pump 1 is disassembled, thereby facilitating manufacturing and cleaning. The conveying channel 21 is moreover integral, thus making it possible to avoid the need to seal the conveying channel 21 at the engaging surface 11 .

At least N-1 transfer channels 21 are provided for arranging the N pumping stages 1a to 1f to communicate.

In the case of the vacuum pump 1 having more than two pumping stages, the width of the conveying channel 21 is equal to or decreases with the pumping stages 1a to 1f, and the first pumping stage 1a is reduced to the second The first conveying channel 21 connecting to the pumping stage 1b has a maximum width.

The stator casing 15 has, for example, an overall cross-section in the form of an ellipse complementary to the joined half shells 9 , 10 . The same elliptical cross-section extends, for example in the longitudinal direction, to form an elliptical vertical cylinder.

As can be seen more clearly in FIGS. 6 and 7 , the at least one groove 20 has, for example, a spiral-shaped portion 20a. The spiral shape makes it possible in this case to be arranged such that the outlet 8 of the pumping end at the bottom communicates with the inlet 7 at the top, in this case, of the subsequent pumping end smoothly without sharp angles. Since there is no abrupt change in the conveying channel 21, it is possible to limit the pressure drop, thereby avoiding an increase in power consumption and heating of the pumped gas and vacuum pump. By controlling the pressure drop in the conveying channel 21, the formation of a dead zone leading to the accumulation of condensable objects can be avoided and, if appropriate, it is made easier to convey the powder together.

For example, the outlet 8 of the pumping stages 1a to 1e communicates with the inlets 7 of the subsequent pumping stages 1b to 1f by means of two conveying channels 21 respectively arranged on one side of the pumping stage. can be arranged as much as possible. Accordingly, the gas flows simultaneously in the two transport channels 21 surrounding the pumping stage, thereby improving the gas transport efficiency ( FIGS. 5 and 7 ). Each pumping stage 1a to 1e can thus be arranged in communication with a subsequent pumping stage 1b to 1f by means of two conveying channels 21 , the two spiral-shaped parts 20a in this case being are connected to each other by first and second straight parts 20b of the conveying channel 21, the first straight part 20b communicates with the inlet 9, and the second straight part 20b has the outlet 8 ) and communicates with (FIG. 7).

It has just been explained that the stator casing 15 with integral conveying channels, which can have different depths or widths, can be easily manufactured at an economical cost, eg by casting, without causing any particular problems in terms of their manufacture. will be understood from

According to a first exemplary embodiment, the vacuum pump 1 provides a seal in one part between the half shells 9 , 10 and in another part between the half shells 9 , 10 and the stator casing 15 . don't have In this case, neither a flat or three-dimensional O-ring seal nor a hardenable seal is provided between the half shells 9 and 10 and between the half shells 9 and 10 and the stator casing 15 . The seal between the pumping stages 1a to 1f is ensured by the fastening of the half shells 9 and 10 together. The seal between the conveying channels 21 is realized by a precise fit of the stator casing 15 on the half shells 9 , 10 . This is made possible in particular by the fact that the stator casing 15 may contain any gas leakage from the pumping stages 1a to 1f or the conveying channel 21 . The seal between the pumped gas and the outside of the vacuum pump 1 can be implemented by using at least two conventional annular seals 22 arranged at the two axial ends of the stator casing 15 .

Thus, as can be seen for example in FIG. 2 , the vacuum pump 1 comprises at least one first annular seal 22 inserted between the edge face of the stator casing 15 and the first end plate 16 , and at least one second annular seal 22 inserted between the edge face of the stator casing 15 and the second end plate 17 . An additional annular seal 22 is provided between the stator casing 15 and the half shells 9, 10, for example between the second end plate 17 and the half shells 9, 10 lying on the side of the lowest pressure. It is inserted in line with the annular seal 22 being inserted.

The annular seal 22 is thus compressed between the flat surface and the fixed surface positioned opposite to each other. As a result, such a seal (22) can be a conventional annular seal, ie a flat O-ring seal, and thus can be made with a simple technique, resulting in low cost. The annular seal 22 is formed, for example, from a relatively economical fluoroelastomer material (FKM). The annular seal can be coated, for example, with a material of the PFA (perfluoroalkoxy) type. These materials are resistant to the most aggressive chemicals.

Fig. 8 shows that the vacuum pump 1 is interposed in one part between the half shells 9, 10 and the stator casing 15 and in another part between two successive pumping stages 1a to 1f. A variant with at least one annular seal 23 is also shown.

More specifically, for example, at least one sealing half-slot 24 is provided on the outer surface of each half-shell 9, 10 to form a circumferential annular slot when the two half-shells 9, 10 are joined. . A circumferential annular slot is interposed between the two inlets 7 and the two outlets 8 of two successive pumping stages to receive the annular seal 23 . Thus, for N pumping stages, there are N-1 circumferential annular slots and associated annular seals 23 . The annular seal 23 may be a conventional seal as described above. The annular seals are flat and parallel to each other, and the annulus is formed in a plane parallel to the plane of the end plates 16 , 17 . This annular seal 23 makes it possible to reinforce the relative seals between the compression chambers and between the conveying channels 21 .

Moreover, in the described embodiment, it is possible to configure the stator casing 15 with a conventional function of the stator.

Accordingly, at least one circulation channel can be provided in the stator casing 15 for thermally moving the stator 2 , in particular for heating or cooling the stator by means of circulation of water.

Likewise, for distribution of a gas such as a neutral gas in the pumping stages 1a to 1f, in particular for diluting a pumped gas such as a reactive gas, for example at least one in the stator casing 15 to react with the pumped gas. A fluid circulation channel may be provided.

Such a fluid circulation channel can be implemented simply in the stator casing 15 by, for example, drilling.

Furthermore, at least one bypass channel interposed between the two inlets 7 or between the inlets 7 and the outlets 8 can be provided in the stator casing 15 , the vacuum pump 1 having a valve (not shown) not) may have a valve disposed in the bypass channel to open and close the bypass channel according to the pressure difference for both sides.

In a manner known per se, the valve has a seat and a movable shutter, the valve may adopt a closed position in which the movable shutter closes the passage of the seat, and an open position in which the movable shutter opens the passage in the seat, the movable shutter The valve can be opened due to the pressure difference on both sides. The movable shutter may be urged to close using a spring.

The valve may be a relief valve disposed at an outlet of the first or second pumping stage communicating with the discharge unit 4 of the vacuum pump 1 . In the open position, it is possible to short the last pumping stage of the vacuum pump due to the relief valve, which can limit the overall swept volume output when a strong gas flow is pumped.

The valve may be a transfer valve disposed at the outlet of the last pumping stage. The transfer valve can prevent the pumped gas from returning to the vacuum pump.

The valve may be a recirculation valve connected between the outlet and the inlet of the first pumping stage. Opening the valve allows the gas to be pumped to recirculate to the same pumping stage as if a strong gas flow was pumped.

Due to the very slight mechanical stress in the stator casing 15 , these various configurations can be implemented. Likewise, due to this low stress, the stator casing 15 is formed of a different material than the half shells 9, 10, which are generally formed of cast iron. For example, the stator casing 15 may be formed of aluminum. These materials weigh less, are inexpensive, and are easy to process. However, in the latter case, the difference between the stator casing 15 and the half shells 9, 10 to constitute a possible clearance between the stator casing 15 and the half shells 9, 1 due to the difference in the coefficient of thermal expansion of the various materials. It is preferred to arrange an annular seal 23 .

9 to 12 show a second embodiment of the multi-stage dry vacuum pump 1 .

In this embodiment, at least one groove 20 is provided in the outer surface of the half shells 9 , 10 in this case, so that at least one transfer by coupling the stator casing 25 ; 26 to the half shells 9 , 10 . The preceding embodiment in that it forms a channel 21, and the conveying channel 21 arranges the outlet 8 of the pumping stages 1a to 1e in communication with the inlet 7 of the subsequent pumping stages 1b to 1f. different from

The at least one conveying channel 21 thus extends from the outer surface of the half shells 9 , 10 at the side of the pumping end. The inner side of the conveying channel 21 is thus accessible when the stator casing 25 ; 26 is removed from the half shell 9 , 10 . The conveying channel 21 is thus easily accessible when the vacuum pump 1 is disassembled, thereby facilitating manufacturing and cleaning. The conveying channel 21 is moreover integral, thus making it possible to avoid the need to seal the conveying channel at the engaging surface 11 .

For example, the stator casing 25; 26 may be formed by a profiled section such as a tube.

The stator casing 25 may have an elliptical cross-section as a whole ( FIG. 10 ).

The stator casing 25 of oval cross section may be complementary to the two half shells 9 , 10 , the half shell itself having an elliptical cross section in the assembled state.

It is possible that the vacuum pump 1 has no seals in one part between the half shells 9 , 10 and in another part between the half shells 9 , 10 and the stator casing 25 ; 26 . The stator casing 25 ; 26 is press-fitted to the half shells 9 , 10 , for example at the axial ends of the stator casing 25 ; 26 .

12 shows a modified example in which the stator casing 26 has a cylindrical cross section as a whole. This stator casing 26 may be complementary to the two half shells 9 , 10 , the half shell itself having an elliptical cross-section in the assembled state.

Moreover, in this example, the stator 2 has a further stator casing 28 surrounding the stator casing 26 , the two stator casings 26 , 28 being in this case cylindrical and coaxial, and the vacuum pump 1 ) to allow the fluid to circulate in the gap 29 lying between the stator casing 26 and the further stator casing 28 to heat the stator 2, in particular to heat or cool the stator by the circulation of water. is composed

Claims (14)

A dry vacuum pump (1), comprising:
- two complementary halves meeting at the mating surface 11 and forming at least two pumping stages 1a to 1f mounted in series between the intake portion 3 and the discharge portion 4 of the vacuum pump 1 . a stator (2) having shells (9, 10), and
- Two rotor shafts (5, 6) configured to synchronously rotate in opposite directions in the pumping stages (1a to 1f) in order to move the pumping target gas between the intake part (3) and the discharge part (4)
In the dry vacuum pump comprising:
- the at least two pumping stages 1a to 1f each have an inlet 7 and an outlet 8 emerging from separate half shells 9 and 10,
- the stator (2) further has a stator casing (15, 25, 26) surrounding the joined half shell (9, 10), the outer surface of the stator casing (15, 25, 26) or the half shell (9, 10) at least one groove 20 is provided to form at least one conveying channel 21 by coupling the stator casings 15, 25, 26 to the half shells 9, 10, at least one conveying channel ( 21) is disposed so that the outlet of the pumping stage (1a to 1e) communicates with the inlet (8) of the subsequent pumping stage (1b to 1f). 2. The pumping end according to claim 1, wherein the outlet (8) of the pumping stage (1a to 1e) is followed by the inlet (8) of the pumping stage (1b to 1f) followed by two conveying channels (21) arranged on one side of the pumping stage ( 7) dry vacuum pump, characterized in that it is arranged to communicate with. 3. Dry vacuum pump according to claim 1 or 2, characterized in that the stator casing (15, 26, 26) has a cross section of an elliptical or cylindrical shape as a whole. 4. Dry vacuum pump according to any one of the preceding claims, characterized in that at least one groove (20) has a helical portion (20a). 5. The helical-shaped two parts (20a) of the two conveying channels (21) by way of first and second straight portions (20b) of the conveying channels (21) according to any one of the preceding claims. Dry vacuum pump, characterized in that connected to each other, the first straight portion (20b) communicates with the inlet (7), and the second straight portion (20b) communicates with the outlet (8). The inlet (7) of the pumping stage according to any one of the preceding claims, wherein the inlet (7) of the pumping end is provided on the first flat surface (12) of the first half shell (9), and the outlet (8) is the second half shell (10) is provided on the second flat surface (13), the first flat surface (12) and the second flat surface (13) is a dry vacuum pump, characterized in that parallel to each other. 7. The stator (2) according to any one of the preceding claims, wherein the stator (2) has first and second end plates (16, 17) coupled to the axial ends of the stator casing (15, 25, 26); The vacuum pump (1) comprises at least one first annular seal (22) interposed between the stator casings (15, 25, 26) and the first end plate (16), the stator casings (15, 25, 26) and the first end plate (16). Dry vacuum pump, characterized in that it has at least one second annular seal (22) interposed between the two end plates (17). 8. The end flange (18) of claim 7, wherein a discharge channel (19) communicating between the outlet (8) and the discharge portion (4) of the last pumping end (1f) is provided in the end flange (18) of the stator (20), said end flange (18) is coupled to the first end plate (16) of the stator (2). 9 . The vacuum pump according to claim 1 , wherein the vacuum pump is in one part between the half shells ( 9 , 10 ) and in another part between the half shells ( 9 , 10 ) and the stator casing ( 15 ). A dry vacuum pump characterized in that it does not have a seal. 9. The vacuum pump according to any one of the preceding claims, wherein the vacuum pump is in one part between the half shell (9, 10) and the stator casing (15, 25, 26) and in another part two successive pumpings. Dry vacuum pump, characterized in that it has at least one annular seal (23) interposed between the stages (1 a to 1f). 11. The stator casing (15) according to any one of the preceding claims, wherein at least one groove (20) is provided in the stator casing (15), and a vacuum pump is provided in the stator casing (15) and has two inlets (7) A dry vacuum pump having at least one bypass channel interposed therebetween or between the inlet (7) and the outlet (8), in which a valve is arranged to open and close the bypass channel according to the pressure difference between both sides of the valve . 12. The stator casing (15, 25, 26) according to any one of the preceding claims, wherein at least one groove (20) is provided in the stator casing (15, 25, 26) for thermal motion of the stator (2) or for pumping a fluid (1a to 1 1 ). Dry vacuum pump, characterized in that at least one fluid circulation channel is provided in the stator casing (15, 25, 26) for dispensing to 1f). 11 . The stator according to claim 1 , wherein at least one groove ( 20 ) is provided on the outer surface of the half shell ( 9 , 10 ), and the stator ( 2 ) comprises a further enclosing stator casing ( 26 ). It has a stator casing (28), wherein the vacuum pump (1) causes a fluid to circulate through the gap (29) located between the stator casing (26) and the further stator casing (28) to heat the stator (2). Dry vacuum pump, characterized in that it is configured. 14. The middle of the vacuum pump (1) according to any one of the preceding claims, wherein the mating surface (11) of the half shell (9, 10) is flush with the plane containing the axis of the rotor shaft (5, 6). Dry vacuum pump, characterized in that through the face.

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