EP3499040A1 - Screw vacuum pump - Google Patents

Abstract

A rotary displacement vacuum pump, tool and method for manufacturing a rotary displacement vacuum pump, in particular screw vacuum pump, comprising the steps of: providing a housing; Providing two pump-active rotors for placement in the housing; Providing each of an alignment surface on the rotors such that the alignment surfaces are in an aligned orientation of the rotors in a predetermined orientation relative to each other; Aligning the rotors based on the alignment surfaces by means of a matched to the alignment surfaces in the predetermined orientation tool.

Description

The present invention relates to a method for manufacturing a rotary displacement vacuum pump, in particular a screw vacuum pump, in which a housing and two pump-active rotors are provided for arrangement in the housing.

The invention also relates to a method for aligning rotors of a rotary displacement vacuum pump, in particular screw vacuum pump.

Furthermore, the invention relates to a Rotationsverdrängervakuumpumpe, in particular screw vacuum pump, with a housing and two pump-active rotors, which are arranged in the housing.

The invention further relates to a tool for aligning two rotors of a rotary displacement vacuum pump.

In addition, the invention relates to a system comprising a Rotationsverdrängervakuumpumpe the aforementioned type and a tool of the aforementioned type.

Rotary displacement vacuum pumps with two rotors usually have complex rotor geometries. The rotors must be aligned with each other as accurately as possible to ensure safe, efficient and efficient operation.

Two screw rotors of an exemplary screw vacuum pump form between each other and with respect to the housing narrow gaps, although to avoid of collision or friction are unavoidable, but are to be kept as small as possible. Such gaps are usually a few tenths of a millimeter. This results in high demands on manufacturing tolerances and assembly accuracy. The rotors are aligned relative to each other and set, for example by applying gears of a synchronizing in the corresponding relative orientation.

Alignment may be hampered, for example, by the occurrence of torques in the assembly of gears on the rotors, e.g. cause a twist of the rotors and / or can affect column size.

In general, the alignment of two rotors, in particular both during manufacture and during maintenance or repair, requires a great deal of effort for a rotary displacement vacuum pump. In an exemplary method of aligning two rotors of a prior art rotary displacement vacuum pump, the rotors are aligned by defining gaps existing between rotor profiles by feeler gauges including rotors, e.g. relative to a housing, are fixed and then Synchronsitionszahnräder be applied. Such a method thus requires many, in particular manual, individual steps. This also requires a variety of special tools and special manual skills.

It is an object of the invention to simplify the alignment of two rotors of a rotary displacement vacuum pump, in particular screw vacuum pump.

This object is achieved by a method according to claim 1, and in particular by the steps: providing each of an alignment surface on the rotors such that the alignment surfaces in an aligned state of the rotors in a predetermined orientation relative to each other, aligning the rotors based on the alignment surfaces by means adapted to the alignment surfaces in the predetermined orientation tool.

By the tool so the rotors are aligned in a particularly simple manner. The inventive method requires in principle no variety of tools, but only one. Although this may be a special tool, but also this orientation is already simplified. Also, no special manual skills are needed to bring the tool into alignment with the alignment surfaces. For example, the person who carries out the alignment does not need any special or only a shorter corresponding training or learning.

In principle, it is advantageous to arrange and / or to design the alignment surfaces in such a way that they do not or only insignificantly influence or impair a pump action of the rotary displacement vacuum pump.

At least one of the alignment surfaces may be e.g. be formed as a flattening. These are particularly easy to produce. It is also easy to produce at least one of the alignment surfaces if it is formed by a slot. For example, the alignment surface can be formed by means of a milling cutter, in particular by being moved transversely, in particular at least substantially perpendicularly to the rotor axis.

Insofar as features relating to at least one of the alignment surfaces are described in the context of this disclosure, these features can be provided in particular for two, in particular both, or a plurality of alignment surfaces.

In a development, the alignment surfaces are arranged in at least substantially the same axial position on the rotors. This must be through the Tool no distance along the rotors are compensated. The tool can therefore be made relatively small. In addition, this leads to an advantageous distribution of force in the tool.

For example, at least one of the alignment surfaces may be flat. A flat alignment surface is also easy to manufacture, for example by a milling cutter, and is advantageous for installation of the tool and a force distribution.

In particular, at least one of the alignment surfaces may be perpendicular to a rotor axis of the corresponding rotor.

According to one embodiment, it is provided that at least one of the alignment surfaces is provided on the rotor during a working step in which a pumping profile of the rotor is formed. As a result, the alignment surface can be arranged and formed in a particularly precise manner in relation to the pump profile. In particular, a clamping of the rotor remains during this step, in particular for a milling of the alignment surface and a milling of the pumping profile, in particular screw profile.

In a further development, the alignment surfaces are each provided at a position on the rotor, which is located in a mounted state of the pump in a pump chamber, in particular in an ejection space. The term "suction space" refers to the total volume of process gas within the housing of the pump. In the pump chamber and in particular in the ejection space is relatively much space, so that the tool can be used thereby easily and reliably.

In particular, the tool for aligning the rotors may be inserted into the housing through an inlet or outlet of the pump. this has the advantage that the rotors in the alignment, in particular completely, can be arranged in the housing. For example, a bearing and / or a seal can be mounted on the rotors prior to the alignment and / or before the application of torque transmission elements and / or synchronization elements. In this case, housing, storage and / or seal are provided in particular for the Rotationsverdrängervakuumpumpe in the finished state and are no longer dismantled after alignment, especially before completion. In addition, the tool can thus be particularly easily introduced through openings, ie inlet and outlet, which are provided anyway in a vacuum pump. In particular, therefore, no additional access must be provided.

It can be advantageously provided that the alignment surfaces are arranged symmetrically in each case in the aligned state of the rotors with respect to a rotor cross-section.

At least one rotor can be provided with a corresponding shape with respect to its alignment surface. As a result, a corresponding imbalance in the rotor is avoided.

In a further development, at least one of the alignment surfaces in the axial direction is provided on one side of a pump-active region of the rotor, on which a torque transmission element, in particular a synchronization element, in particular a gear of a synchronization gear provided on the rotor, in particular fixed. Thus, it is avoided that occurring during assembly of the torque transmitting element torques on the pump-active region of the rotor, in particular his pumping profile, is passed. Instead, the torque is absorbed by the tool. This allows a more precise alignment in the event that torques are expected during assembly. For example, at least one of the alignment surfaces in axial Direction between a gear seat and a pump active region of the rotor can be provided.

A development is characterized in that the tool for abutment with the alignment surfaces of the rotors in the aligned state in each case has a cooperation surface, wherein the cooperation surfaces form a wedge shape. This allows the tool to be applied particularly precisely to the alignment surfaces. For example, in parallel alignment and cooperation surfaces a certain clearance for insertion of the tool must be provided. On the other hand, the wedge shape can be produced practically free of play or applied to the alignment surfaces. It can thus ensure a particularly accurate alignment of the rotors.

In particular, the wedge shape may be self-locking. In this case, any torques in the rotors are automatically absorbed by the tool and the alignment can be performed even more precisely. In addition, the tool does not have to be kept separately in position, which would possibly require an additional holding tool.

The wedge shape may for example have an angle between 1 ° and 10 °, in particular over 3 ° and / or below 8 °, in particular about 6 °. The terms "above" and "below" include the specified values.

In particular, the tool for abutment with the alignment surfaces of the rotors in the aligned state may each have a cooperation surface, wherein the rotors are aligned by bringing the cooperation surfaces into contact with the alignment surfaces.

For example, the rotors can be rotated by the tool into an aligned position. For example, the tool can be guided for alignment between the rotors, in particular in one direction at least substantially perpendicular to the rotor axis. In this case, the force required to rotate the rotors can be introduced, for example, exclusively by means of tools. Alternatively, the rotation can be supported manually on accessible rotor ends, for example.

The object of the invention is also achieved by a method according to claim 12, and in particular by the fact that the rotors are aligned by means of aligning surfaces provided on the rotors by means of a tool adapted to the aligning surfaces.

The object of the invention is also achieved by a Rotationsverdrängervakuumpumpe according to claim 13, in particular in that the rotors each have an alignment surface for aligning the rotors.

The object of the invention is also achieved by a tool according to claim 14, and in particular by the fact that the tool has two cooperation surfaces each for abutment with an alignment surface of a respective rotor of the Rotatationsverdrängervakuumpumpe.

The tool may have, for example, an alignment section and / or a holding section. Both can e.g. be designed as separate parts and, for example, firmly connected, for example screwed and / or welded. The alignment section, in particular its cooperation surface, can in particular be formed by machining, whereby a high precision can be achieved. The holding section can be produced for example with low precision and, for example, be designed as, in particular curved, sheet metal part.

The cooperation surfaces can in particular form a, for example symmetrical, wedge shape. In particular, the cooperation surfaces and alignment surfaces be flat against the rotors and / or aligned in the aligned state at least substantially without play abutment against each other.

The object of the invention is also achieved by a system according to claim 15.

The methods, pumps, tools, and systems described herein may be advantageously developed in accordance with any features of the embodiments or refinements of methods, pumps, tools, and systems described herein.

A tool according to the invention or an alignment according to the invention can, for example, also simplify a method for measuring screw rotors of a screw vacuum pump. In an exemplary such surveying method paired rotors are stored on a roller block and stored rotatably. The rotors are aligned over the tool. Synchronization gears, in particular dummy gears, are applied to the rotors. The tool is removed. The rotors are rolled against each other, with feeler gauge a Mindestspaltmaß along the rotor is determined. A maximum gap must be e.g. can not be determined because it is crucial for a final pressure of the pump and this is easily determinable and in particular anyway determined during a final inspection. Thus, the invention not only facilitates the manufacture of a pump, but also the measurement of rotors.

An exemplary method of manufacturing an exemplary screw vacuum pump having two rotors disposed within a housing will be described below.

The rotors are first inserted into a pumping chamber of the pump or into the housing. Prior to alignment, two end shields are mounted with respective bearings, including fixed and floating bearings, and gasket so that the rotors are fully supported by the final bearing assembly.

Depending on the arrangement of alignment surfaces, an alignment tool is introduced into the suction space through an inlet or outlet flange. The inlet flange is usually larger than the outlet flange. Therefore, the alignment surfaces are provided in particular in an inlet or suction of the suction chamber, to ensure a particularly easy access. The arrangement of components on the respective rotors is advantageously chosen so that torsion of the rotors by assembly-related torques is minimal, e.g. such that gear wheels are arranged on the same rotor end and in the vicinity of the alignment surfaces or the tool position.

The rotors have e.g. Flattening as alignment surfaces for installation of the tool. In order to avoid imbalances, each rotor has a symmetrically arranged pair of flattenings, ie an additional flattening to compensate for the flattening serving as the alignment surface. In particular, in the case of a double-flighted screw profile, a particularly high balancing quality, in particular even before balancing the rotors, can thereby be achieved.

The alignment surfaces of the rotors are machined before assembly together with their screw profile. In this case, a respective alignment surface serve as a reference for the production of the profile. This can form the basis for a particularly precise alignment. The alignment surface can also be used, for example, as a reference for a measurement of a respective rotor, for example by a 3D coordinate measuring machine.

To align the rotors, the tool is guided between the rotors. An alignment portion of the tool is e.g. formed wedge-shaped and rotated the two rotors against each other until the tool rests flat on both sides. This allows a play-free installation of the tool, a high alignment accuracy and relatively large manufacturing tolerances for tools and alignment surfaces, in particular in comparison to parallel alignment surfaces or cooperation surfaces of the tool. Angle and / or distance of the surfaces are in particular to be chosen so that torques can be absorbed during assembly and only a relatively small insertion depth for the tool is necessary. For example, a self-locking angle between 1 ° and 10 °, in particular between 3 ° and 8 °, in particular about 6 ° between the alignment in the aligned state or between cooperation surfaces of the tool to be provided with alignment surfaces.

The tool comprises a precisely machined alignment section and a low cost manufactured retaining section which is connected to the alignment section e.g. connected by screws or welded.

Gears of a synchronization gear are mounted after mounting the rotors in the housing on the rotor, wherein introduced torques are absorbed by the tool. By the gears or the synchromesh the rotors are synchronized with each other. Then the tool is removed.

Fig. 1

zeigt eine Schraubenvakuumpumpe in perspektivischer Ansicht.

Fig. 2

zeigt die Schraubenvakuumpumpe der Fig. 1 in einer Draufsicht.

Fig. 3

zeigt die Schraubenvakuumpumpe der Fig. 1 und 2 in einer Seitenansicht.

Fig. 4

zeigt eine Schnittansicht der Schraubenvakuumpumpe entlang einer in Fig. 3 angedeuteten Schnittebene A-A.

Fig. 5

zeigt einen Tauchkühler der Schraubenvakuumpumpe der Fig. 1 bis 4.

Fig. 6

zeigt in einer perspektivischen Schnittdarstellung einen Ansaugbereich der Schraubenvakuumpumpe der Fig. 1 bis 4.

Fig. 7

zeigt den Ansaugbereich in einer weiteren Schnittdarstellung mit einem Werkzeug zur Ausrichtung von zwei Rotoren der Schraubenvakuumpumpe der Fig. 1 bis 4.

Fig. 8

zeigt die Schnittdarstellung der Fig. 7 in einer Vorderansicht.

Fig. 9

zeigt ein Werkzeug zum Ausrichten von Rotoren, wie es in den Fig. 7 und 8 bei einem Ausrichtvorgang gezeigt ist.

The invention will now be described by way of example only with reference to the schematic drawing.

Fig. 1

shows a screw vacuum pump in a perspective view.

Fig. 2

shows the screw vacuum pump the Fig. 1 in a top view.

Fig. 3

shows the screw vacuum pump the Fig. 1 and 2 in a side view.

Fig. 4

shows a sectional view of the screw vacuum pump along a in Fig. 3 indicated section plane AA.

Fig. 5

shows a submerged cooler of the screw vacuum pump of Fig. 1 to 4 ,

Fig. 6

shows in a perspective sectional view of a suction of the screw vacuum pump of Fig. 1 to 4 ,

Fig. 7

shows the intake in a further sectional view with a tool for aligning two rotors of the screw vacuum pump Fig. 1 to 4 ,

Fig. 8

shows the sectional view of Fig. 7 in a front view.

Fig. 9

shows a tool for aligning rotors, as in the Fig. 7 and 8th is shown in an alignment process.

In the Fig. 1 to 3 a screw vacuum pump 10 is shown, which has a motor 12, a gear box 14, a housing 16, a bearing plate 18 and a cover 20. The screw vacuum pump 10 delivers a process gas from an inlet 22 to a downward, in Fig. 3 visible outlet 24.

For the engine 12, an active liquid cooling is provided which emerges from a housing of the engine 12. For arranged in the interior of the housing 16 and in Fig. 4 visible screw rotors 28 and 30 is also provided an active liquid cooling, which has two cooling lines, which in Fig. 1 are not shown, but their course is indicated by corresponding grooves 32 of the housing 16, in which the cooling lines are pressed. Furthermore, active liquid coolers are provided in the gear box 14 and in the lid 20 and are each formed here as immersion coolers 34, which are described below with reference to FIG Fig. 5 be explained in more detail.

As it is in the Fig. 1 to 4 it can be seen, the housing 16 of the screw vacuum pump 10 has a sidecut 36. The sidecut 36 is arranged in the region of the outlet 24.

In Fig. 4 the screw vacuum pump 10 is shown in a sectional view, the sectional plane of the line AA in Fig. 3 equivalent. There are two screw rotors 28 and 30 visible, each having zweigängige, interlocking screw profiles 38 and 40, which are generated by means of a cycloid profile and have a cylindrical envelope contour and a cylindrical basic shape of the screw base. The screw profiles 38 and 40, in cooperation with the housing 16, form a pump-active area of the screw vacuum pump 10 and repeatedly deliver closed volumes of delivery of the process gas from the inlet 22 to the outlet 24, in FIG Fig. 4 from left to right.

The pumping power of the screw vacuum pump 10 depends on the size and shape of different gaps in the pump active region, which are unavoidable due to the relative movement of rotors 28, 30 and housing 16, but are small and as constant as possible for the purpose of good pumping performance. Temperature changes in the components involved lead to their change in shape. The avoidance, release and general measures described herein Control of heat in the pump 10 thus cause the least possible change in shape and as a result controllable column as possible. The gaps can therefore be designed more precisely, which improves the pumping power and its efficiency.

The screw rotor 28 is directly, so without intermediate clutch, driven by the motor 12. The screw rotor 30, in contrast, is driven via a synchronization gear 42 with toothed wheels 43 in a defined angular relationship with the screw rotor 28.

The motor 12 comprises a housing 44, which is made of aluminum, for example, and in which cooling lines 26 for the active liquid cooling are formed. The motor 12 further includes a wound stator 46 which, together with a magnet carrier 48 mounted on a shaft end of the screw rotor 28, forms an electric motor and a direct drive for the screw rotor 28. The screw rotor 28 forms a rotor of the motor 12. The magnet carrier 48 comprises a plurality of permanent magnets. The motor 12 thus forms a permanent magnet synchronous machine with internal magnets, which is also referred to as IPMSM.

The stator 46 is arranged in a potting body 50 which isolates electrical conductors (not shown) at the stator 46 and leads them in isolation to a circuit board 52. The potting body 50 here, in conjunction with the circuit board 52, forms a vacuum-tight connection of the motor 12 to an electronic control system provided in a region of atmospheric pressure. For example, an external frequency converter for the motor 12 may be provided. Alternatively or additionally, at least part of control electronics for the motor 12 may be provided on the circuit board 52.

In the gear box 14, the synchronization gear 42 is arranged. In the gear box 14 also oil is provided as a lubricant, which is distributed by splash disks 54 via the synchronization gear 42 and adjacent bearings 56.

The waist 36 forms a shield or thermal barrier, in particular for heat produced in the area of the screw rotors 28, 30 during the pumping operation. Characterized in that a small material cross-section remains, and in that a heat path is extended by the change in shape, the heat from the screw rotor, which otherwise spreads in the housing 16, prevented from entering into otherworldly areas. In particular, the oil in the gear box 14 and the bearings 56 are protected from excessive temperatures. The immersion cooler 34 arranged in the gearbox 14 also contributes to the temperature reduction. This is arranged in an oil bath of the gear box 14, not shown, and thus cools the oil directly.

For a respective screw rotor 28 and 30 is adjacent to the bearings 56, which form a fixed bearing here, designed as a deflector 58 lubricant discharge device. A respective deflector 58 forms a barrier for the oil in the gearbox so that it does not enter a pump-active region or a vacuum region, in particular an outlet region. The deflector 58 includes an unspecified Abschleuderkante for the oil. Opposite the Abschleuderkante a drain groove is formed in the housing 16, which absorbs thrown off oil and this passes back into the gear box 14 and in a local oil bath. The oil, which is conveyed or distributed by the spray disks 54 on the gear 42 and bearing 56, is thus removed by the deflectors 58 again from the rotors 28 and 30 respectively.

As a dynamic fluid seal, piston rings are provided on a piston ring carrier 60. These form a non-contact seal and thus avoid frictional heat. The Deflektoren 58 lead back as much oil to the gearbox 14, so that as little as possible oil is present at the piston rings. This achieves an overall reliable sealing effect with particularly low heat production.

The screw rotors 28 and 30 have in their respective screw profile 38 and 40, three sections of different pitch. A in pumping direction first section 62, in Fig. 4 left, forms a suction section and has a constant and the largest slope under the three sections. The first portion 62 is longer than a closed delivery volume in the first portion with respect to a screw axis 63 extending along a respective rotor 28, 30, respectively. A second portion 64 has a plurality of subsections, which are not further referenced, with different but each constant pitches in the screw profile 38 and 40, wherein the slopes are lower than in the first section. The second section 64 forms the longest section here. A third section 66 of even lower pitch forms an ejection section. In the third section, again, there is a constant slope. Due to the reduced slope along the pumping direction, an internal compression is effected, which compresses the process gas even before the ejection.

The rotors 28, 30 and the screw profiles 38, 40 can be particularly easy to design and manufacture by providing the constant sections. As it is based on Fig. 4 As can be seen, an extended first portion 62 leads to correspondingly elongated gaps between the screw profiles 28, 30 and the housing 16, so that the path or the gap from the inner compression at the transition of the sections 62 and 64 towards a suction chamber or suction area 67 longer is. Accordingly, the sealing effect of the column is increased accordingly especially at high differential pressures leads to an improved sealing of the inner compression relative to the suction region 67.

The screw vacuum pump 10 thus has an internal compression. The screw rotors 28, 30 of the pump 10, in cooperation with the housing 16, repeatedly closed delivery volumes. Their size is greater at an inlet-side end or in section 62 than at an outlet-side end or in section 62. The size of a delivery volume is determined by a cross-section of a screw profile 38, 40 and its pitch.

The size of a delivery volume on the inlet side or in the section 62 determines a theoretical pumping speed of the screw pump 10. The pitch of the screw profile 38, 40 is constant on the inlet side over section 62, so that the delivery volume is compressed only after completion by the internal compression. If a respective rotor 28, 30 closes a respective delivery volume too early or too late, or if the internal compression begins too early, the theoretical pumping speed of the pump decreases.

The size of a respective delivery volume on the outlet side or in section 66 determines the power consumption of the pump in operation at an achievable final pressure. The ratio of the sizes of the delivery volume on the inlet side and outlet side or in the sections 62 and 66 corresponds to the ratio of the internal compression of the pump.

In section 66, the pitch over several revolutions of the screw profile 38, 40 is constant. The slope corresponds approximately to the minimum of achievable by a particular machining tool pitch and is thus, in particular with cost considerations, manufacturing technology. Due to the fact that several revolutions, that is to say a plurality of closed delivery volumes, are provided in section 66, a return flow due to a pressure difference between balanced in the columns. Overall, in particular the overall gradient along the rotors 28, 30 and the size of the gaps formed between the rotors 28, 30 and between rotors 28, 30 and the housing 16 determine the vacuum performance data of the pump, ie in particular the pumping speed and an achievable final pressure.

The screw profiles 38, 40 have by their zweigängige configuration on a particularly low imbalance. Thus, for example, there are no compensating elements, such as e.g. Compensation masses that require additional space, and / or compensation holes, in which material can deposit, necessary. The pump can be operated with the two-speed cycloidal screw profiles 38, 40 in a wide speed range, in particular with speed control, and / or for example in a stand-by mode.

The compression of the process gas in general generates heat, which is dissipated in the screw pump 10 primarily by a liquid cooling. In Fig. 4 the grooves 32 provided for this purpose are visible. Cooling lines of the liquid cooling extend here and preferably in the longitudinal direction over a wide range of screw profiles, in particular over at least half the length of the screw profiles. In particular, the liquid cooling is arranged in the region or in the vicinity of an internal compression.

At an inlet end of the housing 16 of the bearing plate 18 is attached. This carries, inter alia, a further storage with bearings 68, which form a loose storage. In contrast to an opposite, arranged at an outlet side housing end bearing plate 70 which is formed integrally with the housing 16 but may also be formed separately, the bearing plate 68 is formed as a separate component, but may also be integrally formed.

On the inlet side, spray disks 54, deflectors 58 and a piston ring carrier 60 with a plurality of piston rings are also provided, which operate in accordance with the outlet-side arrangement. On the inlet side, a further, separately executed oil bath is provided in the lid 20. Also for this oil bath a dip cooler 34 is provided. Alternatively or additionally, for example, a cooling line in a wall of the bearing plate 14 and / or the cover 20 may be provided, in particular encapsulated

At the beginning of a pumping operation by the pump 10, there is usually substantially the same pressure at the inlet 22 as at the outlet. On the other hand, during the pumping down, the pressure at inlet 22 drops to a final pressure that is substantially zero with respect to resultant forces. Thus, the pressure at the outlet 24 exerts a force on the rotors 28, 30 which is different than at the beginning of the pumping operation. To compensate for this force, e.g. a biasing device, in particular a spring, be provided, which is provided in particular at a floating bearing of the rotor and / or inlet side. The biasing device can for example also absorb forces acting on the rotors by means of helical gears and / or generally guarantee a design-appropriate preloading of the bearings, regardless of the operating state, with changing pressures or pressure ratios.

In Fig. 5 a dip cooler 34 is shown as it is arranged in the gear box 14 and in the cover 20 of the screw vacuum pump 10. In this embodiment, the immersion coolers 34 are thus formed identically, which leads to a small number of parts and low production costs.

The immersion cooler 34 has a cooling line 72 which extends through a heat sink 74. The heat sink has a structuring to increase the surface of the heat sink in order to optimize the heat transfer. The immersion cooler 34 also has a flange 76 with which the immersion cooler 34 is attached.

In Fig. 6 the suction region 67 of the screw vacuum pump 10 is illustrated in a perspective sectional view. In the suction region 67, respective suction-side ends of the screw profiles 38 and 40 are arranged which, due to their rotation and in cooperation with an edge of a closing surface 77, repeatedly close up delivery volumes and convey along the rotor axes to the outlet 24.

The screw rotors 28 and 30 each have an alignment surface 78, of which in Fig. 6 only that of the rotor 28 is visible. In addition, both rotors 28 and 30 have an alignment surface 78 respectively opposite corresponding shape or a compensation surface 80. Of the compensation surfaces 80 is in Fig. 6 again only that of the rotor 30 visible. The compensation surface 80 avoids a balancing by the corresponding alignment surface 78th

The alignment surface 78 is here in each case formed as a flattening, which is formed by a milled slot in the rotor. The slot runs perpendicular to the rotor axis. The alignment surface 78 is flanked by walls 79. Conveniently, here the compensation surface 80 is formed accordingly.

In Fig. 7 an alignment process for the screw rotors 28, 30 is shown by means of a tool 82. The tool 82 and the rotors 28, 30 are shown in an aligned position or an aligned state. Cooperation surfaces 84 of the tool 82, of which in Fig. 7 because of the perspective, only the one that is facing the rotor 30 is visible, are in contact with the alignment surfaces 78th

The position of the tool 82 with respect to a direction perpendicular to the rotors 28, 30, here in the up-down or longitudinal direction of the tool, substantially determines the orientation of the rotors 28, 30. To substantially prevent movement of the tool 82 in only allow this direction, the walls 79 form a guide for the tool 82nd

The tool 82 is for aligning the rotors 28, 30 through the inlet 22 in the suction chamber, here in the. Intake portion 67 of the screw vacuum pump 10 introduced. In the scoop space and the alignment surfaces 78 are arranged. The tool 82 can therefore very easily be used to align the rotors 28, 30. In particular, the rotors 28, 30 are already fully supported and sealed at the time of alignment, and do not have to be separately aligned beforehand.

Based on the side view of Fig. 8 The interaction of tool 82 and rotors 28, 30 is further illustrated. As it is in Fig. 8 can be seen, the cooperation surfaces 84 are flat and wedge-shaped with respect to each other. In the illustrated, aligned position, the cooperation surfaces 84 rest against the alignment surfaces 78 without play. In this position, the alignment surfaces 78 are correspondingly V-shaped and symmetrically aligned.

To bring the rotors 28, 30 in the aligned position, it only requires the introduction of the tool 82 from above with a certain force. By the tool 82, the rotors 28, 30 thereby rotated in the aligned position.

The cooperation surfaces 84 are aligned with each other such that the tool 82 is self-locking. Therefore, a torque occurring in a screw rotor 28, 30 does not result in a displacement of the tool 82 and a deviation from the aligned position. Instead, become Torques in the rotors 28, 30 are automatically absorbed by the tool 82.

The tool 82 is in Fig. 9 shown individually. It is formed in two parts and comprises an alignment section 86 and a holding section 88. The alignment section 86 is manufactured precisely by means of a milling method. The holding portion 88 is formed as a bent sheet metal part and can thus be produced very inexpensively. The alignment portion 86 is bolted to the retaining portion 88. It can be seen that the tool 82 is relatively small and flat. It is very handy and overall relatively inexpensive to produce.

LIST OF REFERENCE NUMBERS

10

Screw vacuum pump

12

engine

14

gearbox

16

casing

18

end shield

20

cover

22

inlet

24

outlet

26

cooling line

28

screw rotor

30

screw rotor

32

groove

34

immersion cooler

36

sidecut

38

screws profile

40

screws profile

42

synchronizing gear

43

gear

44

casing

46

stator

48

magnet carrier

50

potting

52

circuit board

54

splasher

56

warehouse

58

deflector

60

Piston ring carrier

62

first section

63

screw axis

64

second part

66

third section

67

suction

68

warehouse

70

end shield

72

cooling line

74

heatsink

76

flange

77

end surface

78

alignment

79

wall

80

compensation area

82

Tool

84

cooperation area

86

aligner

88

holding section

Claims (15)

Method for producing a rotary displacement vacuum pump, in particular screw vacuum pump (10),
with the steps: Providing a housing (16), Providing two pump-active rotors (28, 30) for arrangement in the housing (16), Providing in each case one alignment surface (78) on the rotors (28, 30) such that the alignment surfaces (78) are in a predetermined orientation relative to one another in an aligned state of the rotors (28, 30), Aligning the rotors (28, 30) on the basis of the alignment surfaces (78) by means of a tool (82) adapted to the alignment surfaces (78) in the predetermined orientation. Method according to claim 1,
characterized in that
at least one of the alignment surfaces (78) is formed as a flattening. Method according to claim 1 or 2,
characterized in that
the alignment surfaces (78) are arranged in at least substantially the same axial position on the rotors (28, 30). Method according to at least one of the preceding claims,
characterized in that
at least one of the alignment surfaces (78) on the rotor (28, 30) is provided during a step in which a pumping profile (38, 40) of the rotor (28, 30) is formed. Method according to at least one of the preceding claims,
characterized in that
the alignment surfaces (78) are each provided at a position on the rotor (28, 30), which is in a mounted state of the pump (10) in a suction chamber (67), in particular in a discharge space. Method according to at least one of the preceding claims,
characterized in that
the tool (82) for directing the rotors (28, 30) through an inlet (22) or an outlet of the pump is introduced into the housing. Method according to at least one of the preceding claims,
characterized in that
the alignment surfaces (78) are each arranged symmetrically in the aligned state of the rotors (28, 30) with respect to a rotor cross-section. Method according to at least one of the preceding claims,
characterized in that
at least one of the alignment surfaces (78) is provided in the axial direction on one side of a pump active region of the rotor (28, 30) on which a torque transmission element (43) is also provided on the rotor (28, 30). Method according to at least one of the preceding claims,
characterized in that
the tool (82) for abutment with the alignment surfaces (78) of the rotors (28, 30) in the aligned state each have a cooperation surface (84), wherein the cooperation surfaces (84) form a wedge shape Method according to claim 9,
characterized in that
the wedge shape is self-locking. Method according to at least one of the preceding claims,
characterized in that
the tool (82) for abutment with the alignment surfaces (78) of the rotors (28, 30) in the aligned state each having a cooperation surface (84), wherein the rotors (28, 30) are aligned by the cooperation surfaces (84) in Plant with the alignment surfaces (78) are brought. Method for aligning rotors (28, 30) of a rotary displacement vacuum pump, in particular screw vacuum pump (10),
wherein the rotors (28, 30) are aligned by means of an alignment surface (78) provided on the rotors (28, 30) by means of a tool (82) adapted to the alignment surfaces (78). Rotationsverdrängervakuumpumpe, in particular screw vacuum pump (10), in particular produced by a method according to one of claims 1 to 11, with
a housing (16) and two pump-active rotors (28, 30), which are arranged in the housing (16),
wherein the rotors (28,30) each have an alignment surface (78) for aligning the rotors (28, 30). A tool (82) for aligning rotors (28, 30) of a rotary displacement vacuum pump (10), the tool (82) having two co-operating surfaces (84) each for engagement with an alignment surface (78) of a respective rotor (28, 30) of the rotary displacement vacuum pump (10). 10). A system comprising a rotary displacement vacuum pump according to claim 13 and a tool according to claim 14.

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