JP2009121491A - Frictional vacuum pump with chassis, rotor and housing, and device fitted with such a frictional vacuum pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily adapt a frictional vacuum pump to various kinds of applications requested by customers. <P>SOLUTION: The friction vacuum pump (1) comprises a chassis (5), a stator (3), a rotor (4) and a housing. All functional elements of the pump are combined into one unit (27). The unit itself is inserted into housings (19, 55) adapted to a specific application. Using this procedure, any special connection housing can be eliminated and optimal conductance can be achieved. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a friction vacuum pump having a chassis, a rotor, and a casing. The invention further relates to a device comprising a chamber to be evacuated and a friction vacuum pump of this type.

  From DE-A-43 14 419 various friction vacuum pumps (turbomolecular pumps, pumps with turbomolecular pump stages and other friction pump stages) having a common and commercially available configuration are known. These friction vacuum pumps have a chassis, which is equipped with a drive motor and on which a rotor is supported. In addition, the pump casing is supported on the chassis. The pump casing surrounds the rotor and stator and, to some extent, the chassis. The casing ensures the mutual arrangement of these components. In addition, the casing serves to accurately center the stator, which consists of the stator half-ring disk and the spacer ring, so that the small gap required in the friction vacuum pump can be maintained. The casing seals the vacuum pump to the outside. Finally, the casing is provided with a connection flange arranged on the end face, by means of which the friction vacuum pump is connected to a device having a chamber to be evacuated. Because there are different types and sizes of flanges, it is necessary for manufacturers of friction vacuum pumps to make, prepare and meet different customer demands for different types of friction vacuum pumps. .

  Furthermore, it is known from DE-A-43 31 589 to provide a plurality of connection openings in a friction vacuum pump. These connection openings have different pressure levels. This type of friction vacuum pump advantageously has chambers separated from one another by a restriction, and is used to exhaust the particle beam device (eg mass spectrometer) that generates and maintains various pressures during operation in these chambers. Useful. This type of application significantly increases the cost of producing and / or preparing a friction vacuum pump suitable for the needs of as many customers as possible.

DE-A-43 14 419 DE-A-43 31 589

  The problem underlying the present invention is to enable the friction vacuum pump to be easily adapted to various applications desired by customers.

  To achieve the above object, according to the friction vacuum pump having a chassis, a stator, a rotor and a casing according to the present invention, a friction vacuum pump having a chassis (5), a stator (3), a rotor (4) and a casing ( 1), the casing consists of two casing parts (18; 19, 55), the first inner casing (18) being generally cylindrically shaped and surrounding the stator (3), And a through opening (28, 35) for the gas entering the pump, and the second casing (19, 55) is a bore (19) that accommodates the first casing with the pump components therein. 22) and connection openings (36, 37, 44).

  The friction vacuum pump according to the present invention is characterized in that the second casing (19) includes one connection flange (39, 43).

  In addition, the friction vacuum pump according to the present invention is characterized in that the connection flange (39) is arranged on the second casing (19) on the side.

  The friction vacuum pump according to the present invention is characterized in that the second casing (55) is a constituent part of the casing or casing portion of the device (51) having a chamber to be evacuated.

  The friction vacuum pump according to the present invention is characterized in that a seal (24) is provided between the inner casing (18) and the outer casing (19, 55) within the range of the high vacuum side of the pump. .

  Further, the friction vacuum pump according to the present invention includes a flange in which inner and outer casings (18; 19, 55) are fixed to the chassis (5) so as to be disengageable within a range of the front vacuum side of the pump. It is characterized by being.

  Further, the friction vacuum pump according to the present invention is characterized in that the inner casing (18) is provided with an edge (20) facing inward on the high vacuum side.

  In addition, the friction vacuum pump according to the present invention is characterized in that the edge (20) facing inward forms a first stator ring disposed on the high vacuum side.

  Further, in the friction vacuum pump according to the present invention, the step-shaped reduced diameter portion (23) of the hole (22) of the outer casing (19, 55) is assigned to the end surface on the high vacuum side of the inner casing. It is characterized by that.

  Further, the friction vacuum pump according to the present invention includes an O-ring (between the end surface of the inner casing (18) and the step portion (23) formed by diameter shrinkage of the outer casing (19, 55)). 24).

  In addition, the friction vacuum pump according to the present invention is characterized in that the end portion on the high vacuum side of the inner casing (18) forms a through opening (28) for gas entering the pump.

  The friction vacuum pump according to the invention is also characterized in that the inner casing (18) is provided with at least one further downstream through opening (35) for the incoming gas.

  In the friction vacuum pump according to the present invention, one or a plurality of connecting passages are formed in the outer casing (19, 55), and the connecting passages are single openings to be exhausted with the through openings (28, 35). Alternatively, it is characterized in that a connection between a plurality of chambers (52 to 54) is generated.

  In order to achieve the above object, according to the apparatus having a chamber to be evacuated, a casing, and a friction vacuum pump according to the present invention, the chamber to be evacuated (52 to 54), the casing (55), and to be evacuated In a device having a friction vacuum pump connected to the chamber and also having a casing, the casing of the friction vacuum pump (1) consists of two casing parts (18; 19, 55), The inner casing (18) of 1 has a generally cylindrical shape, has through holes (28, 35) for gas surrounding the stator (3) and entering the pump, and The second casing (19, 55) has a hole (22) and a connection opening (36, 37, 44) for accommodating the first casing together with the pump components therein, and the second casing. Grayed (19) is provided with a connecting flange (39, 43), and apparatus is characterized in that it is coupled with the friction vacuum pump via the flange (39, 43).

  In order to achieve the above object, according to the apparatus having a chamber to be evacuated, a casing, and a friction vacuum pump according to the present invention, the chamber to be evacuated (52 to 54), the casing (55), and to be evacuated In a device having a friction vacuum pump connected to the chamber and also having a casing, the casing of the friction vacuum pump consists of two casing parts (18; 19, 55), the first inside The casing (18) is generally cylindrical, has a through hole (28, 35) for the gas surrounding the stator (3) and entering the pump, and the second casing. (19, 55) has a hole (22) and a connection opening (36, 37, 44) for accommodating the first casing with the pump components therein, and a second casing ( 9) characterized in that it is a component of a provided with a connecting flange (39, 43), and the outer casing (19) housing or housing part of the apparatus itself of the friction vacuum pump (55).

  In the apparatus according to the present invention, the friction vacuum pump is configured in multiple stages, the chambers (52, 53, 54) are arranged side by side on the side of the friction vacuum pump, and the chamber is an inner casing. Connected to the inlet (26, 29) of the friction pump stage (12, 13, 14) via the through opening (28, 35) in (18) and the connection opening (36, 37) of the common casing (55). It is characterized by being.

  In order to achieve the above object, according to the friction vacuum pump having the chassis, stator, rotor and casing according to the present invention, the chassis (5), stator (3), rotor (4) and casing are provided. In the friction vacuum pump, the component part of the pump is an insert united into one unit (27).

  Further, the friction vacuum pump according to the present invention is characterized in that functional elements of the pump such as an inner casing (18) or other components (tensile stay, clip, etc.) are combined into an insert.

  In order to achieve the above object, according to the friction vacuum pump having the chassis, stator, rotor and casing according to the present invention, the chassis (5), stator (3), rotor (4) and casing are provided. In order to perform the function of the casing in the friction vacuum pump, two component elements (18; 19, 55; 61) are provided, and the first inner component element (18, 61) is a chassis. (5), the stator (3) and the rotor (4) are used for mutual arrangement, centering and holding, forming a unit together with these components, and the second component houses this unit It is characterized by being a casing (19, 55) which carries out.

  The friction vacuum pump according to the present invention is characterized in that the first constituent element is formed by a tensile stay system (61).

  The friction vacuum pump according to the present invention is characterized in that the tensile stay system (61) has a plurality of tensile stays (62) for coupling the stator (3) to the chassis (5). .

  The friction vacuum pump according to the present invention is characterized in that the tensile stay (62) passes through the stator (3) in parallel with the axis.

  The friction vacuum pump according to the present invention is characterized in that the stator (3) has a plurality of stator rings.

  The friction vacuum pump according to the present invention is characterized in that the tensile stay (62) penetrates the stator ring.

  In the friction vacuum pump according to the present invention, the tensile stay (62) is composed of two parts, each of which includes a front vacuum side tensile stay section (63) having a head (64) and a head. It comprises a high vacuum side tensile stay section (65) provided with a section (66).

  In the friction vacuum pump according to the present invention, the length of the head (64) of the tensile stay section (63) on the front vacuum side is such that the high vacuum stage (12) and the front vacuum stage (13 or 13, 14). The axial extension of the through-opening (35) between them is determined.

  Further, in the friction vacuum pump according to the present invention, the heads (64) of the front vacuum side tensile stay section (63) are each provided with a thread on the end face, and the high vacuum side tensile stay is located in the thread. The section (65) is screwable.

  According to the present invention, this problem is solved by the following. That is, the casing is composed of two casing parts, and the first inner casing is generally cylindrical and has a through hole for gas surrounding the stator and entering the pump. And the second casing has a hole for receiving the first casing together with the pump components therein. This measure makes it possible to distribute the functions described at the outset of a conventional one-piece casing into two casings. The inner casing ensures the mutual arrangement of the individual components of the friction vacuum pump. This produces a frictional vacuum pump in the form of an insert, which itself can be subjected to a large number of functional tests, for example a balance test. The outer casing serves to adapt the customer's desire to a friction vacuum pump that can function without the outer casing. There is no longer any need to fabricate or prepare various types of friction vacuum pumps, just one or a few pump units (inserts, cartridges) that can function universally, compactly and reliably, as well as each customer's desire It is only necessary to produce an outer casing that conforms to

  A particular advantage of the present invention is that it is possible to allow the customer to configure the second outer casing. It is only necessary to inform the customer of the external dimensions of the insert-type friction vacuum pump. Particularly simple for the customer is a hole through which the customer can insert an insert-type friction vacuum pump in the casing or casing part of the device (equipment, device, etc. having one or more chambers to be evacuated). Is to form. The casing or casing part of the customer's device then forms the second outer casing of the friction vacuum pump according to the invention in an operable state. This eliminates the need for a separate expensive connection casing. Furthermore, the conductance loss due to the connection of the friction vacuum pump close to the chamber is reduced, and thus the low chamber pressure associated with the process is realized. An optimal conductance state is achieved.

FIG. 2 shows a friction vacuum pump according to the invention with three pump stages. It is the figure which showed the turbo-molecular vacuum pump by this invention. 1 is a view showing an apparatus equipped with a friction vacuum pump according to the present invention. It is a longitudinal cross-sectional view of the insertion body which has a tension stay. It is a cross-sectional view of an insert having a tensile stay.

  In the following, the details of the present invention will be described in detail with reference to the embodiments shown in FIGS.

  In FIG. 1, a friction vacuum pump 1 having a stator 3, a rotor 4, and a chassis 5 is shown. There are motor drive units 6 and 7 in the chassis 5, and the armature 7 is supported in the chassis 5 via bearings 8. A shaft 9 protruding from the chassis 5 is coupled to the armature 7, and this shaft supports the rotor 4. The axis of rotation of the rotor system is indicated at 11.

  The friction vacuum pump 1 shown in FIG. 1 has a total of three pump stages 12, 13, 14 of which two (12, 13) are turbo molecular vacuum pump stages and one (14). Is configured as a molecular pump stage (Hallbeck pump stage). A pump outlet 17 is connected to the molecular pump stage 14.

  According to the invention, the pump 1 comprises two casings 18, 19. The inner casing 18 is generally cylindrical and surrounds the stator 3. The inner casing is provided with an inwardly directed edge 20 on its high vacuum side end face, which edge is in contact with the stator 3 and in this case simultaneously forms the upper stator ring. The casing 18 is fixed to the chassis 5 on the front vacuum side, and is also fixed by a flange 21. The flange 21 and the chassis 5 are vacuum-tightly connected to each other. For this purpose, a seal ring 21 ′ is arranged between the flange 21 and the chassis 5.

  The outer casing 19 has an inner hole 22 with an inwardly facing step 23 whose width is equal to the width of the edge 20 of the first casing 18. In order to seal the gap between the two casings 18, 19 towards the high vacuum side of the pump 1, there is a seal 24 between the edge 20 and the step 23, which seal is preferably of the casing 18. It is put in the end face. A radial seal is also possible. The casing 19 also has a device such as a flange 25 for fixing the casing 19 to the chassis 5 or the casing 18 on the front vacuum side. If this fixing is removed, the unit formed by the inner casing 18 and the constituent parts therein can be taken out from the hole 22 as a whole. This unit forms an insert 27 that is independent of the second casing 19.

  The first pump stage 12 on the high vacuum side consists of four pairs of rotor blade rows and stator blade rows. The inlet, which is an effective gas passage for this pump stage, is shown at 26. The edge 20 surrounds the gas passage surface 26 and forms a through-opening 28 for the gas entering the pump 1. A second pump stage 13 is connected to the first pump stage 12, and this second pump stage comprises three pairs of stator blade rows and rotor blade rows. The inlet of the second pump stage is indicated at 29.

  The second pump stage 13 is spaced from the first pump stage 12. This selected spacing (height) a ensures the possibility of free approach of the gas molecules to be transported to the gas inlet 29. The distance a is preferably greater than ¼ of the diameter of the rotor system 4 and is preferably greater than ３.

  The Hallbeck pump following the second pump stage has a rotating cylindrical section 30 on the outside and inside of this cylindrical section, in a known manner, a stator element 33 with thread grooves 31, 32, respectively. 34 are facing each other.

  Another opening formed by the inner casing 18 is located laterally and is indicated at 35. This opening serves for the penetration of the gas supplied directly to the inlet 29 of the second pump stage 13.

  The role of the outer casing 19 is to connect the pump 1 or the two pump stages (12, 13) of this pump with the customer's equipment. In the embodiment shown in FIG. 1, the casing 19 is configured such that the planes of all the connection openings 36, 37 are on the sides. Thereby, in particular, the distance from the opening 37 to the associated gas inlet 29 is very small, so that conductance losses that impede the suction capacity of the pump stage 13 can be ignored. This is also true for another intermediate connection located downstream of the intermediate connection 37/29. By the way, the diameter of the connection opening 37 exceeds approximately twice the height a. This measure also helps to reduce the conductance loss between the inlet 29 and the connection opening 37. Each lateral connection opening can have one flange. In the embodiment shown in FIG. 1, a common flange 39 is provided.

The illustrated pump 1 or its pumping elements (stator blades, rotor blades, thread groove stages) are preferably constructed as follows. That is, a pressure of 10 ⁻⁴ to 10 ⁻⁷ mbar, preferably 10 ⁻⁵ to 10 ⁻⁶ mbar is generated in the range of the connection opening 36, and approximately 10 ⁻² to 10 ⁻ in the range of the connection opening 37. It is configured so that a pressure of ⁴ mbar is generated. This makes it necessary for the first pump stage 12 to produce a compression ratio of 10 ² to 10 ⁴ , preferably a compression ratio greater than 100. Depending on the second pump stage, a large suction capacity (for example 200 l / s) is produced. Subsequent two-stage Hallbeck pump stages (29, 31; 29, 32) ensure great pre-vacuum resistance, so that the suction capacity of the second pump stage in the usual manner is independent of the pre-vacuum pressure. is there.

  This object can be achieved by correspondingly configuring the blades of the first pump stage 12 if a particularly large suction capacity is not required within the connection opening 36. Another possibility resides in placing a throttle 38 in front of the inlet 26 of the first pump stage so that the inner diameter of this throttle determines the desired suction capacity.

  FIG. 2 shows a single-flow frictional vacuum pump 1 whose pumping surface is formed exclusively by stator blades 41 and rotor blades 42 (turbomolecular vacuum pump). The second outer casing 19 supports a flange 43 on its end face, and this flange surrounds a connection opening 44 arranged on the end face. To provide this type of pump 1 with another type and / or size of flange, it is only necessary to remove the outer casing 19 and instead provide a casing with the desired flange.

  FIG. 3 shows a device 51 according to the invention comprising chambers 52, 53, 54 to be evacuated and an insert-shaped unit 27 as described in FIG. The casing of the device--for example, the particle beam device--is largely constructed in one piece and is indicated at 55. In the immediate vicinity of the chambers 53, 54 to be evacuated, the casing has a hole 22 in which the insert 27 is located. The chambers 53 and 54 are connected to the respective inlets 26 and 29 through through openings 28 and 35 and connection openings 36 and 37 in the casing 18 of the insert 27. By incorporating the insert 27 in the casing 51 of the device, special connection means are omitted. The spacing between the chambers 53, 54 to be evacuated and the inlets 26, 29 is excellently short.

  The core of the idea of the present invention lies in that a fully functional unit (insert, cartridge) of the friction vacuum pump is releasably held in a casing adapted for the application. The role of the inner casing 18 as described above is to combine the functional elements of the friction vacuum pump into the desired unit. Instead of a casing, other components that serve this purpose, such as tensile stays, clips, etc., can also be used. Importantly, in order to carry out the function of a normal casing, two components 18 or 19, 55 are provided in the subject of the present invention. In the embodiment shown in FIGS. 1-3, both components are formed by two concentric casings, the inner casing of which serves to center, interleave and hold the chassis 5, the stator 3 and the rotor 4. This forms an insert that can be operated independently and is independent of the outer casing. The outer casing 19, 55 seals the vacuum pump outwards, whether via a connection flange or by itself being a component of the device with a chamber to be evacuated. Useful for connecting to the room to be.

  It is particularly advantageous to use a tensile stay system instead of the inner casing in the inner insert. This tensile stay system allows the inner insert to be configured more compactly. Furthermore, the components assembled by the tensile stay system can be manufactured more easily. For example, the tensile stay performs the centering of the stator ring, so that the stator ring itself no longer has to have a centering means.

  4 and 5 show an embodiment for an inner insert 27 with a tensile stay system 61 (FIG. 4: longitudinal section of the insert 27; FIG. 5: crossing of the insert 27 at the height of the opening 35). Area view). This tensile stay system includes three to six (or more) tensile stays 62 and holes and threads in the components (chassis 5, stator 3) that are grouped together by the tensile stay system 61. Yes.

  As can be seen from FIGS. 4 and 5, the opening 35 extends around the entire circumference of the insert 27 and is interrupted solely by the tensile stay 62. Thereby, the approach to the inlet 29 of the gas molecule pump stage 13 (shown in plan view in FIG. 5) is almost unimpeded and free. The fixing of the outer casing takes place at the flange 21 of the chassis 5, whether it is the second casing 18 that performs another function of the pump casing or the casing 55 that is a component of the device with the chamber to be evacuated. .

  FIG. 4 makes it possible to recognize the structure of the tension stay 62 which is particularly advantageous. The tensile stay is composed of two parts. A tensile stay section 63 with a head 64 on the front vacuum side passes through the stator ring of the pump stage 13 and the stator element 33 outside the pump stage 14. The end of the tensile stay section with the thread is screwed into the flange 21 of the chassis 5. The length of the head 64 determines the axial extension of the opening 35. In the range of the end face on the high vacuum side of the tensile stay section, the heads 64 each have one inner thread, and the high vacuum side tensile stay section 65 can be screwed into the inner thread. . The head 66 of the tensile stay section 65 is in contact with the uppermost stator ring of the pump stage 13. In other respects, this tensile stay section 65 passes through the stator ring of the pump stage 12 so that when screwed, it simply couples the high vacuum stage 12 to the remaining stages 13 and 14. Also, the stator ring is centered.

  DESCRIPTION OF SYMBOLS 1 Friction vacuum pump, 3 Stator, 4 Rotor, 5 Chassis, 6 Motor drive device, 7 Motor drive device, Armature, 8 Bearing, 9 axis, 11 Rotating axis, 12 Pump stage, 13 Pump stage, 14 Pump stage, 17 Outlet , 18 casing, 19 casing, 20 rim, 21 flange, 21 'seal ring, 22 inner hole, 23 step, 24 seal, 25 flange, 26 inlet, gas passage surface, 27 insert, insert body unit, 28 Through opening, 29 inlet, 30 cylindrical section, 31 thread groove, 32 thread groove, 33 stator element, 34 stator element, 35 opening, 36 connection opening, 37 connection opening, 38 throttle, 39 flange, 41 stator blade, 42 rotor blade , 4 Flange, 44 connection opening, 51 device, 52 chambers, 53 chambers, 54 chambers, 55 casing, 61 tensile stay system, 62 tensile stays, 63 tensile stay segments, 64 heads, 65 tensile stay segments, 66 heads Part, a interval (height)

Claims (27)

  In a friction vacuum pump (1) having a chassis (5), a stator (3), a rotor (4) and a casing, the casing consists of two casing parts (18; 19, 55), the first inner casing (18) is generally cylindrically shaped, has a through opening (28, 35) for the gas surrounding the stator (3) and entering the pump, and the second casing (19) , 55) having a hole (22) for accommodating the first casing together with the pump components therein and a connection opening (36, 37, 44), a stator, a rotor And a friction vacuum pump having a casing.   2. Friction vacuum pump according to claim 1, characterized in that the second casing (19) is provided with one connecting flange (39, 43).   3. Friction vacuum pump according to claim 2, characterized in that the connecting flange (39) is arranged laterally in the second casing (19).   2. Friction vacuum pump according to claim 1, characterized in that the second casing (55) is a component of the casing or casing part of the device (51) having a chamber to be evacuated.   5. A seal according to claim 1, wherein a seal is provided between the inner casing and the outer casing within the range of the high vacuum side of the pump. Friction vacuum pump according to item.   2. Inner and outer casings (18; 19, 55) comprising flanges releasably secured to the chassis (5) within the area of the front vacuum side of the pump. The friction vacuum pump according to any one of 5 to 5.   7. Friction vacuum pump according to claim 1, characterized in that the inner casing (18) is provided with an edge (20) facing inward on the high vacuum side.   8. Friction vacuum pump according to claim 7, characterized in that the inwardly facing edge (20) forms a first stator ring arranged on the high vacuum side.   9. The stepped reduced diameter portion (23) of the hole (22) of the outer casing (19, 55) is assigned to the end face on the high vacuum side of the inner casing. The friction vacuum pump according to any one of the above.   An O-ring (24) is provided between an end face of the inner casing (18) and a step (23) formed by diameter shrinkage of the outer casing (19, 55). Item 10. The friction vacuum pump according to Item 5 or 9.   11. The high-vacuum end of the inner casing (18) forms a through-opening (28) for gas entering the pump. The friction vacuum pump described.   12. Friction vacuum pump according to claim 11, characterized in that the inner casing (18) is provided with at least one further downstream through opening (35) for incoming gas.   One or more connecting passages are formed in the outer casing (19, 55), and the connecting passages are formed between the through openings (28, 35) and the one or more chambers (52 to 54) to be evacuated. The friction vacuum pump according to claim 11, wherein a connection between the friction vacuum pumps is generated.   In a device having a chamber (52-54) to be evacuated, a casing (55), a friction vacuum pump connected to the chamber to be evacuated and also having a casing, the casing of the friction vacuum pump (1) Consists of two casing parts (18; 19, 55), the first inner casing (18) being generally cylindrically shaped, surrounding the stator (3) and entering the pump The through-hole (28, 35) for gas and the second casing (19, 55) has a hole (22) and a connection opening for receiving the first casing together with the pump components therein. (36, 37, 44), the second casing (19) is provided with a connecting flange (39, 43), and the device is friction vacuumed via the flange (39, 43). Characterized in that it is combined with the pump, the chamber should be evacuated device having a casing, a friction vacuum pump.   In a device having a chamber (52-54) to be evacuated, a casing (55) and a friction vacuum pump connected to the chamber to be evacuated and also having a casing, the casing of the friction vacuum pump has two The casing part (18; 19, 55) consists of a first inner casing (18), which is generally cylindrical in shape, for the gas surrounding the stator (3) and entering the pump. Through-holes (28, 35) and the second casing (19, 55) includes a hole (22) for accommodating the first casing together with the pump components therein and a connection opening (36, 37, 44), the second casing (19) is provided with connecting flanges (39, 43), and the outer casing (19) of the friction vacuum pump is mounted on the device itself. Characterized in that it is a component of the pacing or casing portion (55), the chamber should be evacuated device having a casing, a friction vacuum pump.   The friction vacuum pump is configured in multiple stages, the chambers (52, 53, 54) are arranged side by side on the side of the friction vacuum pump, and the chamber has a through opening (28 in the inner casing (18). , 35) and the connection opening (36, 37) of the common casing (55) and the inlet (26, 29) of the friction pump stage (12, 13, 14). The apparatus of claim 15.   In a friction vacuum pump having a chassis (5), a stator (3), a rotor (4), and a casing, the component part of the pump is an insert united into one unit (27). A friction vacuum pump having a chassis, a stator, a rotor and a casing.   18. Friction vacuum pump according to claim 17, characterized in that the functional elements of the pump, such as the inner casing (18) or other components (tensile stays, clips, etc.) are combined in the form of an insert.   In a friction vacuum pump having a chassis (5), a stator (3), a rotor (4) and a casing, two components (18; 19, 55; 61) are provided to perform the function of the casing. The first inner component (18, 61) serves to interleave, center and hold the chassis (5), stator (3) and rotor (4), together with these components one A friction vacuum pump comprising a chassis, a stator, a rotor and a casing, characterized in that it forms a unit and the second component is a casing (19, 55) containing this unit.   20. Friction vacuum pump according to claim 19, characterized in that the first component is formed by a tensile stay system (61).   21. Friction vacuum pump according to claim 20, characterized in that the tensile stay system (61) comprises a plurality of tensile stays (62) for connecting the stator (3) with the chassis (5).   The frictional vacuum pump according to claim 21, characterized in that the tensile stay (62) passes through the stator (3) in parallel to the axis.   23. Friction vacuum pump according to any one of claims 19 to 22, characterized in that the stator (3) has a plurality of stator rings.   24. Friction vacuum pump according to claim 23, characterized in that the tensile stay (62) penetrates the stator ring.   The tensile stay (62) is composed of two parts, each having a front vacuum side tensile stay section (63) with a head (64) and a high vacuum side with a head (66). 25. Friction vacuum pump according to any one of claims 19 to 24, characterized in that it consists of a tensile stay section (65).   The length of the head (64) of the tension stay section (63) on the front vacuum side is the axis of the through opening (35) between the high vacuum stage (12) and the front vacuum stage (13 or 13, 14). 26. A frictional vacuum pump according to claim 25, characterized in that it determines the extension in the direction.   The heads (64) of the front vacuum side tensile stay section (63) are each provided with a thread on the end face, and the high vacuum side tensile stay section (65) can be screwed into the thread. 27. The frictional vacuum pump according to claim 25 or 26, characterized in that

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