EP3623630B1 - Vacuum pump - Google Patents

Description

The present invention relates to a vacuum pump, in particular screw vacuum pump, according to the preamble of claim 1 and a method for operating such a pump. A pump according to the preamble of claim 1 is in the GB 2 167 495 A disclosed. Another vacuum pump with a disc rotating in an oil filling is in the EP 2 957 772 A2 disclosed.

The JP S61 212688 A teaches in connection with a rotary displacement pump to arrange a magnet in the area of an oil filling of a lubrication pump of the rotary displacement pump in order to collect metallic contaminants.

Many types of vacuum pumps require effective cooling. This applies in particular to screw vacuum pumps, since they generally have a high power density and correspondingly high heat production. The cooling is often supported by an oil system, which advantageously also serves to lubricate moving components such as rotors and gear elements. The heat is dissipated, for example, via a housing or a heat exchanger, which is arranged in particular in an oil fill in the oil system.

It is an object of the invention to improve the temperature control of a vacuum pump of the type mentioned in the introduction.

This object is achieved by a vacuum pump with the features mentioned in claim 1, and in particular in that the disk or disks are designed and arranged to cause an at least essentially unidirectional flow in the oil filling at least in the region of the heat exchanger due to their rotation .

This improves the heat transfer between the oil filling and the heat exchanger. This is particularly true in contrast to a swirled flow or to a situation in which different flow directions are formed in the oil, so that the heat exchange cannot use the full flow path along the heat exchanger.

Another advantage is particularly evident in comparison to a vacuum pump, in which the heat of the oil filling is dissipated at least also via a housing section holding the oil filling. Typically, oil is sprayed through a rotating disc over an inner wall of the housing. However, this requires a minimum speed, since oil drops only detach after a certain centrifugal force. In the vacuum pump according to the invention, the heat is effectively dissipated even without spraying. The temperature control of this vacuum pump is therefore essentially independent of the speed or at least relatively effective at low speeds. Particularly in connection with a frequency converter for a rotor motor, this enables a special speed flexibility, which also makes the use of the pump significantly more flexible.

Last but not least, the flow to the heat exchanger, which is improved according to the invention, can also reduce its size compared to that without an improved flow. This can save installation space and costs.

In this context, the term "unidirectional" does not necessarily mean that the flow may only be straight. Rather, the flow course can also run along a rather complex, in particular curved and / or circular, path, as long as it runs at least essentially only in one direction along this path. The flow can consequently, for example, also essentially have a circular path which corresponds to the shape of the disk, in particular runs concentrically to it.

According to the invention, a flow is thus generated which only runs in one direction. A counter-current flow, which is caused in particular by other parts immersed in the oil filling and rotating in opposite directions, and large, chaotic turbulences, in particular if they are generated by a counter-current flow, are to be avoided. To achieve the advantages according to the invention, however, a laminar flow does not necessarily have to be present as long as the flow as a whole or macroscopically runs essentially unidirectionally in the region, in particular along, the heat exchanger. Within the unidirectional flow, a turbulent flow is even particularly advantageous for the heat transfer.

According to the invention, the unidirectional flow is thus generated in the area of the heat exchanger, as a result of which the capacities of the heat exchanger can be used particularly well. In principle, further heat exchangers, in particular each with its own unidirectional flow, can also be provided.

For example, a second oil filling and a second heat exchanger arranged therein can be provided. In this case, for example, a second unidirectional flow can also be generated in the area of the heat exchanger by means of a further disk, in order also for particularly good heat dissipation there to care. First and second oil fillings or first and second heat exchangers can advantageously be provided on opposite rotor ends.

Furthermore, a third heat exchanger, for example, the specification "third" serving only for differentiation and no "second" heat exchanger being required, can be provided in the first oil filling and in the region of which, for example, a second flow can also be formed which corresponds to that of the first Heat exchanger is opposite, as long as the second flow does not run in the area of the first heat exchanger or is at least reduced to an insignificant degree there. In this way, a unidirectional flow can be generated on both heat exchangers and a particularly effective heat exchange can be realized.

The disk according to the invention is generally formed by a component which is immersed in the oil filling and rotates with a rotor and / or gear element and has a certain radial extent. The disk can thus also be formed, for example, by a gearwheel, in particular arranged on the rotor. In particular, however, the disk is not a gearwheel, but in particular a component separate therefrom, which, however, can be attached to a gearwheel, for example. In the case of a disk separate from the gearwheel, it is particularly advantageous if the gearwheel or gearwheels are arranged in such a way that they are not immersed in the oil filling during operation. In principle, the disk can, for example, be formed in one piece with or separately from the rotor.

The pane does not have to be designed as a closed surface element. For example, it can also have openings, for example even be designed as a spoke wheel.

To generate the unidirectional flow, the pump is in particular free of a disk rotating in opposite directions in the same oil filling, at least in the area of the heat exchanger. However, two or more disks can also be provided, which can be arranged and / or designed, in particular, for the same, in particular synchronous and / or parallel, rotation with the first disk. Two or more disks can be provided, for example, on the same rotor and / or gear element, as a result of which synchronism and synchronicity can be achieved in a simple manner.

In principle, the unidirectional flow can be brought about, for example, by arranging all the disks immersed in the oil filling, in particular all the immersed, rotating components, for the same rotation.

The heat exchanger can advantageously be designed as a separate part, and in particular can be detachably fastened in the oil filling or in a chamber provided for this purpose. A chamber for the oil filling can in principle be formed, for example, by a housing section. In particular, the, in particular first, housing section can be designed such that it is formed separately from a second housing section for a pump-active subarea of the pump and / or separately from a third housing section for a drive motor of the pump, the specifications "second" and "third" "again only serve to differentiate. In an advantageous example, the first housing section can be provided between a second housing section for a pump-active subarea and a third housing section for a drive motor. Alternatively, the heat exchanger can be designed, for example, as part of a second or third housing section.

According to the invention, it is provided that the vacuum pump comprises a housing section for the oil filling and the housing section has an opening, in particular an assembly opening, through which the heat exchanger can be introduced or inserted into the housing section, in particular inserted or inserted, and / or removed.

The heat exchanger can, for example, be fastened or fastened to a peripheral region and / or flange of the opening, in particular in a sealing and / or sealing manner. For this purpose, the heat exchanger can have, for example, a fastening flange. For example, an O-ring can be provided for the seal, in particular between a fastening flange of the heat exchanger and the peripheral region and / or flange of the opening.

The heat exchanger can have, for example, at least one, in particular a supply and a discharge, connection for a heat exchange fluid, it being possible for the connection, in particular a housing section, to be arranged for the oil filling. The connection can advantageously be angled. This enables space to be saved.

According to a further development, the heat exchanger extends along a longitudinal axis, and is in particular elongated. A particularly good heat exchange results if a heat transfer body of the heat exchanger has a length that is at least twice as large, in particular at least three times as large as a width of the heat transfer body. The disk can advantageously be arranged parallel to the longitudinal axis of the heat exchanger, in particular so that the flow in the oil filling runs essentially along the heat exchanger.

In a further advantageous embodiment, the heat exchanger at least partially surrounds the disk. The heat exchanger can, for example, be ring-shaped, oval or rectangular. If several co-rotating disks are provided, in particular at least one can be enclosed by the heat exchanger and at least one can be arranged next to the heat exchanger.

For example, it can be provided that a removable heat exchanger can be tilted for removal, e.g. to remove the above-described enclosing of the disc and to be able to remove the heat exchanger without dismantling the disc. Alternatively or additionally, it can be provided that a cover and / or housing section for the oil filling can be tilted, for example in order to remove the above-described enclosing of the disk and to be able to remove the heat exchanger with the housing section without dismantling the disk.

In a further embodiment, the heat exchanger has a line for a heat exchange fluid. The line can, for example, run around and / or enclose the panes. Alternatively or additionally, the line can run at least substantially along the flow caused by the disk.

The pump can, for example, also have two rotors, with in particular only one carrying at least one disk. In particular, it can be provided that the vacuum pump comprises two rotors arranged in parallel and coupled by a gear, of which only one carries at least one disk in the area of the heat exchanger for rotation in the oil filling.

The vacuum pump can be designed, for example, as a screw vacuum pump with two screw rotors or as a Roots pump with two Roots rotors, with in particular only one rotor in the region of the heat exchanger and / or at one rotor end carrying and / or driving to rotate.

In a further development, the heat exchanger is part of a temperature control system for the heat exchanger. The temperature control system can have, for example, a cooling device, for example a further heat exchanger Heat exchange with the ambient air. The temperature control system can, for example, alternatively or additionally comprise a heating device. As a result, the pump, the rotor and / or a gear in the area of the heat exchanger can advantageously and quickly be heated to a desired operating temperature. In addition, no additional components are required on the pump housing, in particular on a housing section of the oil filling. The temperature control system can in particular have a control or regulation, in particular in connection with a temperature sensor. In this way, desired operating temperatures, in particular in special operating conditions, such as when starting the pump, in final pressure operation, at full load and / or when pumping heavy gases, can be advantageously set.

The heat exchanger can have, for example, an, in particular elongated, heat transfer body. The heat transfer body can comprise an aluminum material, in particular cast aluminum material, for the purpose of advantageous heat exchange. Alternatively or additionally, at least one line for a heat exchange fluid can be provided, for example, the line having a stainless steel. In particular, the line can be cast in the heat transfer body.

In a further exemplary embodiment, it is provided that an opening for the heat exchanger is arranged at least essentially at a deepest point in an interior and / or an oil chamber of a housing section for the oil filling. The opening can thus be used as an oil drain opening, so that a further opening provided for this purpose, in particular with a separate oil drain screw, can be dispensed with. In particular, therefore, no further oil drain opening is provided on the housing section and / or for its oil filling. The housing section can be, in particular light, asymmetrical, in particular to improve the drainage of the oil.

According to a further development, it is provided that at least one magnet is arranged on the heat exchanger, in particular in the oil filling. The use of magnets to collect abrasion particles in the oil is generally known. The arrangement on the heat exchanger in connection with the unidirectional flow brought about by the invention results in an extremely high effectiveness of the magnet in the particle collection, since it is thus at least essentially directly in the flow. As a result, a particularly large amount of oil passes through the magnets each time and can release its abrasion particles to them. This allows the oil to be kept much cleaner and the life of the pump to be improved. If, for example, the heat exchanger is additionally detachable and / or removable, the magnet can be removed particularly easily, in particular without further dismantling of the pump, with the heat exchanger and cleaned of the collected abrasion particles. This simplifies the maintenance of the pump and significantly reduces the associated costs.

If at least one magnet is arranged on the heat exchanger, this enables particularly good agglomeration of abrasion particles in the oil. Maintenance is also simplified since the magnets can be serviced together with the heat exchanger.

The disk can generally define, for example, an inlet region, a longitudinal region and / or an outlet region, in particular at least one inlet region and one outlet region on the heat exchanger for the oil flow. These are generally understood to mean areas in which the flow essentially flows towards the heat exchanger, along the heat exchanger or away from the heat exchanger.

According to one embodiment it is provided that the magnet is arranged in one of these areas, in particular in the inlet and / or in the outlet area. This can further improve the particle collection. In a particularly advantageous example, at least one magnet is provided in the inlet and outlet area and / or in the case of an elongated heat exchanger at respective end areas.

Furthermore, the heat exchanger and / or a heat transfer body can have a plurality of recesses and / or projections, which are at least essentially aligned along a flow course caused by the disk. Recesses and projections are basically known for the purpose of increasing the surface of a heat transfer body in order to improve the heat transfer. In the example described here, the recesses or projections additionally take on a flow-guiding function, which further improves the quality, in particular homogeneity, of the flow with regard to the heat transfer. In addition, the alignment of the recesses or projections described here has the effect that the geometry of the heat exchanger or heat transfer body only offers a relatively low resistance to the flow, which likewise improves the flow quality and in particular the flow velocity, so that particularly good heat transfer is made possible as a result.

Such projections can be designed, for example, as ribs and / or fins. The recesses and / or projections can in particular be provided on a heat transfer body of the heat exchanger and / or in an inlet area and / or an outlet area for the flow. A respective recess or a respective projection can advantageously extend with a longitudinal extension along the flow course.

In a further development, the recesses and / or projections are at the top and / or at the bottom or at the top and / or bottom of the heat exchanger or a heat transfer body with respect to an intended operating position the vacuum pump on the heat exchanger or on the heat transfer body. On the one hand, this arrangement is particularly favorable in terms of flow technology and, on the other hand, it is particularly simple to manufacture, for example in a casting process.

The or part of the recesses and / or projections can, for example, be arranged obliquely with respect to a longitudinal axis of the, in particular elongated, heat exchanger, for example at an angle of at most 45 ° to the longitudinal axis. The oblique arrangement has an advantageous effect in particular in an inlet and / or outlet area.

In particular, a plurality of recesses and / or projections can be oriented at different angles with respect to the longitudinal axis. For example, angles of recesses and / or projections which are positioned differently along the longitudinal axis can be different with respect to the longitudinal axis, in particular be stepped along the longitudinal axis and / or decrease towards a center of the pane and / or heat transfer body. These measures further improve the flow-guiding function and heat transfer.

Arrows and / or tapered pairs of recesses and / or projections are also conceivable, for example. For example, one of two recesses or projections, in particular positioned identically in the longitudinal direction, can each be arranged at the top and bottom of the heat exchanger, in particular being arranged at an incline.

Basically, in particular flow-conducting and / or supporting recesses and / or projections can also be provided on other components, in particular a housing section for the oil filling and / or on adjacent housing sections, such as a bearing plate, an intermediate flange and or a motor housing.

In general, the geometries of the heat exchanger and / or nearby components can thus advantageously be adapted to and / or correspond to a shape of the disk, in particular essentially defining an annular path concentric to the disk for an oil flow.

The object of the invention is also achieved by a method for operating a vacuum pump, in particular a screw vacuum pump, according to the independent method claim.

The independent aspects described here can of course be further developed advantageously in the sense of the described embodiments and features of the other aspects.

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 einen weiteren Wärmetauscher bzw. Tauchkühler.

Fig. 7

zeigt schematisch eine Anordnung von Ausnehmungen und/oder Vorsprüngen an einem Wärmetauscher.

Fig. 8

zeigt eine weitere derartige Anordnung.

The invention is explained below by way of example only with reference to the schematic drawing.

Fig. 1

shows a screw vacuum pump in perspective view.

Fig. 2

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

Fig. 3

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

Fig. 4

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

Fig. 5

shows an immersion cooler of the screw vacuum pump of the 1 to 4 .

Fig. 6

shows another heat exchanger or immersion cooler.

Fig. 7

shows schematically an arrangement of recesses and / or projections on a heat exchanger.

Fig. 8

shows another such arrangement.

In the 1 to 3 A vacuum pump designed as 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 conveys a process gas from an inlet 22 to a downward, in Fig. 3 visible outlet 24.

Active liquid cooling is provided for the motor 12 and emerges from a housing of the motor 12. For arranged inside the housing 16 and in Fig. 4 visible screw rotors 28 and 30 an active liquid cooling is also provided, which has two cooling lines, which in Fig. 1 are not shown, the course of which is indicated by corresponding grooves 32 of the housing 16, into which the cooling lines are pressed. Furthermore, heat exchangers designed as active liquid cooling systems are provided in the gearbox 14 and in the cover 20 and are referred to here as immersion coolers 34, which are described below with reference to FIG Fig. 5 are explained in more detail.

Like it in the 1 to 4 can be seen, the housing 16 of the screw vacuum pump 10 has a waist 36. The waist 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 corresponds. Two screw rotors 28 and 30 are visible, each having two-start, interlocking screw profiles 38 and 40, which are generated with the aid of a cycloid profile and have a cylindrical envelope contour and a cylindrical basic shape of the screw base. In cooperation with the housing 16, the screw profiles 38 and 40 form a pump-active area of the screw vacuum pump 10 and convey it repeatedly closed delivery volumes of the process gas from inlet 22 to outlet 24, in Fig. 4 from left to right.

The pumping capacity of the screw vacuum pump 10 depends on the size and shape of various gaps in the pumping area, which are unavoidable due to the relative movement of the rotors 28, 30 and housing 16, but are small and as constant as possible for good pumping capacity. Temperature changes in the components involved lead to their shape change. The measures described here for avoiding, dissipating and generally controlling heat in the pump 10 thus bring about the least possible change in shape and consequently the most manageable gaps. The gaps can therefore be designed more precisely, which improves the pump performance and its efficiency.

The screw rotor 28 is driven directly by the motor 12, that is to say without an intermediate coupling. In contrast, the screw rotor 30 is driven via a synchronization gear 42 with gear wheels 43 in a defined angular relationship to the screw rotor 28. The rotors 28 and 30 are thus coupled together.

The motor 12 comprises a housing 44, which is made of aluminum, for example, and in which cooling lines 26 are formed for the active liquid cooling. The housing 44 can, for example, also have an aluminum casting material and in particular cooling lines 26 cast therein, which for example have a stainless steel or are produced therefrom. The motor 12 also includes a wound stator 46 which, together with a magnet carrier 48 attached to 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 insulates electrical conductors (not shown in more detail) in the stator 46 and insulates them 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 control electronics provided in a range of atmospheric pressure. For example, an external frequency converter can be provided for the motor 12. Alternatively or additionally, at least part of control electronics for the motor 12 can be provided on the circuit board 52.

The synchronizing gear 42 is arranged in the gear box 14. In the gear box 14, oil is also provided as a lubricant, which is distributed through a disk 54, also referred to as a spray disk, via the synchronizing gear 42 and adjacent bearings 56. In operation, an oil filling in which the disk 54 is immersed and in which it rotates with the rotor 30 to which it is attached is in operation in the gearbox 14. The gear box 14 thus forms an example of a housing section for the oil filling.

The waist 36 forms a shield or a heat barrier, in particular for heat that is produced in the area of the screw rotors 28, 30 during pump operation. Due to the fact that a small material cross section remains and because the change in shape extends a heat path, the heat from the screw rotor, which otherwise spreads in the housing 16, is prevented from reaching areas beyond. In particular, the oil in the gearbox 14 and the bearings 56 are protected from excessive temperatures. The immersion cooler 34 arranged in the gearbox 14 also contributes to reducing the temperature. This is arranged in the oil filling of the gear box 14, not shown, and thus cools the oil directly.

A lubricant discharge device designed as a deflector 58 is provided for a respective screw rotor 28 or 30 adjacent to the bearings 56, which form a fixed bearing here. A respective deflector 58 forms a barrier for the oil in the gearbox so that it does not get into a pump-active area or a vacuum area, here in particular an outlet area. The deflector 58 comprises a not-shown edge for the oil. Opposite the flinging edge, a drain groove is formed in the housing 16, which takes up flung oil and directs it back into the gear box 14 or into an oil filling there. The oil, which is conveyed or distributed by the spray disk 54 to the gearbox 42 and bearing 56, is thus removed again by the deflectors 58 from the rotors 28 and 30, respectively.

Piston rings are provided on a piston ring carrier 60 as a, in particular dynamic, fluid seal. These form a non-contact seal and thus avoid frictional heat. The deflectors 58 return as much oil as possible to the gearbox 14, so that as little oil as possible is present on the piston rings. An overall reliable sealing effect is achieved with particularly low heat production.

The screw rotors 28 and 30 have three sections of different pitch in their respective screw profile 38 and 40, respectively. A first section 62 in the pumping direction, in Fig. 4 left, forms a suction section and has a constant and the greatest slope among the three sections. With respect to a screw axis 63, which runs along a respective rotor 28 or 30, the first section 62 is longer than a closed delivery volume in the first section. A second section 64 has a plurality of subsections, which are not referenced in more detail, with different, but in each case constant, slopes in the screw profile 38 or 40, the slopes being lower than in the first section. The second section 64 here forms the longest section. A third Section 66 with an even lower slope forms an ejection section. In the third section there is again a constant slope. Due to the reduced slope along the pump direction, an internal compression is brought about, which compresses the process gas before it is expelled.

The rotors 28, 30 and the screw profiles 38, 40 can be designed and manufactured particularly simply by providing the constant sections. As it is based on Fig. 4 It can be seen that an elongated first section 62 leads to correspondingly elongated gaps between the screw profiles 28, 30 and the housing 16, so that the path or the column from the internal compression at the transition of the sections 62 and 64 to a scooping area or suction area 67 is longer is. The sealing effect of the gaps is correspondingly increased, which leads to an improved sealing of the inner compression with respect to the suction area 67, in particular at high differential pressures.

The screw vacuum pump 10 thus has an internal compression. In cooperation with the housing 16, the screw rotors 28, 30 of the pump 10 include repeatedly closed delivery volumes. Their size is larger at an inlet end or in section 62 than at an outlet 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 slope.

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

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 sections 62 and 66 corresponds to the ratio of the internal compression of the pump.

In section 66, the pitch is constant over several revolutions of the screw profile 38, 40. The slope corresponds approximately to the minimum of the slope that can be achieved by a specific machining tool and is therefore, particularly in consideration of costs, production-related. Due to the fact that several revolutions, that is to say several closed delivery volumes, are provided in section 66, a backflow due to a pressure difference between the gaps is compensated. Overall, the overall gradient profile along the rotors 28, 30 and the size of the gaps formed between the rotors 28, 30 and between the rotors 28, 30 and the housing 16 determine the vacuum performance data of the pump, in particular the pumping speed and an achievable final pressure.

The screw profiles 38, 40 have a particularly low unbalance due to their two-start design. For example, there are no compensating elements, e.g. Compensating compounds that require additional installation space and / or compensating holes in which material can be deposited are necessary. The pump can be operated with the two-start cycloid 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 generally generates heat, which in the screw pump 10 is primarily dissipated by 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 one 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 area or in the vicinity of an internal compression.

The bearing plate 18 is fastened to an inlet-side end of the housing 16. Among other things, this carries a further bearing with bearings 68, which form a loose bearing. In contrast to an opposite bearing plate 70 arranged on an outlet-side housing end, which is integrally formed with the housing 16 but can also be formed separately, the bearing plate 68 is formed as a separate component, but can also be formed integrally.

A spray disk 54, deflectors 58 and a piston ring carrier 60 with a plurality of piston rings are also provided on the inlet side and operate in accordance with the arrangement on the outlet side. A further, separately executed oil filling is provided in the cover 20 on the inlet side. An immersion cooler 34 is also provided for this oil filling. As an alternative or in addition, a cooling line can also be provided, in particular encapsulated, in a wall of the end shield 14 and / or the cover 20.

At the beginning of a pumping process by the pump 10, there is usually essentially the same pressure at the inlet 22 as at the outlet. In contrast, during the pumping down, the pressure at the inlet 22 drops to a final pressure which is essentially zero with regard to the resulting forces. Thus, the force exerted on the inlet 22 on the rotors 28, 30 is different than at the beginning of the pumping-out process, or a force is only exerted on the rotors 28, 30 in the longitudinal direction only by the pressure on the outlet 24, so that the resulting force in each case Rotor is different than at the beginning of the pumping process. In order to compensate for this force, a prestressing device, in particular a spring, can be provided, which is provided in particular in the case of a loose bearing of the rotor and / or on the inlet side. The pretensioner can also be used, for example Helical gear wheels absorb forces acting on the rotors and / or generally ensure that the bearings are preloaded in accordance with the design, regardless of the operating state when the pressures or pressure conditions change.

In Fig. 5 A heat exchanger or immersion cooler 34 is shown as it is arranged in the gearbox 14 or in the cover 20 of the screw vacuum pump 10. In this embodiment, the immersion coolers 34 are thus of identical design, which leads to a small number of parts and low manufacturing costs.

The immersion cooler 34 has a heat exchange fluid line, in particular a cooling line 72, which runs through a heat transfer body, in particular a cooling body 74. The line 72 is made of a stainless steel and cast in an aluminum material of the heat transfer body 72. The heat transfer body 74 has a structuring which increases the exchange-active surface in order to increase the surface of the heat sink. The immersion cooler 34 also has a flange 76 with which the immersion cooler 34 is fastened to an opening of the gearbox 14 provided for this purpose. In the fastened state, the heat transfer body 74 is arranged in the oil filling and the lines 72 are arranged outside the gearbox 14, as is shown, for example, in FIG Fig. 4 is visible. The lines can also advantageously be designed with an angled connection area, which saves installation space.

In Fig. 6 A further heat exchanger 34 is shown in a perspective view, a disk 54 being indicated schematically as it rotates in an oil filling (not shown) in which the heat transfer body 74 is also arranged. The heat transfer body 74 is elongated and surrounds the disk 54. The heat transfer body 74 essentially forms a rectangular ring around the disk 54. The cooling lines 72 run in particular here through the heat transfer body 74, also enclose the disk 54 and have a U-shape in their course.

If the disk 54 rotates in the oil filling, for example in a direction of rotation 78, it accelerates the oil in the oil filling in at least a region close to the disk 54 in the corresponding direction. As in Fig. 6 is clearly visible, this direction corresponds to the longitudinal direction or longitudinal axis of the heat transfer body 74 or the heat exchanger 34. As a result, the oil flows along a large length of the heat transfer body 74, so that an effective forced heat exchange is achieved over the entire length. In this case, such a flow occurs on both sides of the disc 54, so that the heat transfer body 74 is also flowed to on both sides of the disc 54 and can advantageously be used.

As a result of the rotation, the disk 54 thus generates a unidirectional flow in the area of the heat exchanger 34 and thereby defines an inlet area 80, an outlet area 82 and an intermediate longitudinal area 84 for the oil. In the inlet area 80, oil is essentially accelerated and / or sucked in and flows against the heat transfer body 74. In the longitudinal region 84, the flow essentially runs along the heat transfer body 74. In the outlet region 82, the oil essentially releases itself from the influence of the disk 54, which also emerges from the oil filling in the vicinity of the outlet region 82. The oil flows away from the heat transfer body 74 in the drainage area 82. The disk 54 takes part of the oil with its rotation 78 and distributes it, for example, to gear elements of the pump, for example gearwheels 43. Another part of the oil is gradually removed by the remaining oil filling slowed down. The part of the oil which is taken from the oil filling by the disk 54 as it rotates gradually flows back into the oil filling due to the force of gravity, so that an essentially constant oil level is maintained during operation.

The disk 54 forms an essentially unidirectional flow in the area of the heat exchanger 34 or the heat transfer body 74. This has an essentially circular shape, which corresponds to the shape of the disk 54. In the absence of further, in particular counter-rotating, disks, this flow is unidirectional, that is, it only runs in one direction along its path. As a result, a large section, in particular essentially the entire heat transfer body 74, can be effectively used for heat transfer.

For example, it is also possible to provide further disks, in particular arranged parallel to the disk 54, which rotate in the same direction with the disk 54. In this way, the unidirectional flow can be additionally strengthened and the heat transfer can be further improved. Another disk can be arranged, for example, outside the ring described by the heat transfer body 74.

Two magnets 85 are provided on the heat transfer body 74 and are arranged in the inlet area 80 and in the outlet area 82. They are thus arranged in a region of relatively strong flow, but on the other hand do not block the disk 54 from rotating. Because of their proximity to the disk and their arrangement in the flow path, the magnets 85 are passed through by a relatively large amount of oil, so that ferromagnetic abrasion particles in the oil are particularly effectively collected on the respective magnet 85 and essentially remain there until they are cleaned manually. The cleaning can be carried out, for example, by removing the heat exchanger 34 from a relevant housing section. So that there is no need to disassemble the disk 54, it can generally be provided that the heat exchanger 34 is arranged such that it can be tilted slightly downward, so that removal is easily possible. It can be seen that this arrangement of the magnets 85 on the heat exchanger 34 is extremely advantageous with regard to maintenance and cleaning of the pump. The fact that the magnets 85 can now be cleaned so easily can also overall, the concentration of abrasion particles customary in operation is reduced, and thus the life of the pump as a whole and in particular the life of rotor bearings, gear wheels and / or oil as the operating medium are increased.

In Fig. 7 an arrangement of recesses and / or projections 86 is shown schematically, as advantageously on the heat transfer body of a heat exchanger, for example according to one Fig. 6 , can be arranged. In the following, ribs are considered as examples for the recesses and / or projections, the explanations also applying to recesses and / or projections in the more general sense.

In Fig. 7 Ribs 86.1, 86.2 and 86.3 are shown, which are aligned along a flow course 88 caused by the disk (not shown here). A first rib 86.1 is arranged obliquely, here approximately at an angle of 45 °, so that it is aligned approximately parallel to the flow course 88 in an inlet area 80. The flow entering the area of the heat exchanger in the inlet area 80 is thus opposed by a slight resistance due to the geometry of the heat exchanger and, at the same time, the rib 86.1 has a flow-guiding function.

A rib 86.2 is arranged in a longitudinal running area 84 and extends essentially along the longitudinal axis of the heat exchanger. The rib 86.2 thereby favors the fact that in the longitudinal running area 84 the flow also runs along the heat exchanger, in particular over the longest possible length.

Another rib 86.3, also arranged obliquely, is provided in a drain area 82. This supports the directional drainage of the oil.

Overall, the ribs 86.1, 86.2 and 86.3 form a geometry which essentially defines an annular path for the oil flow which is concentric with the disk. As a result, a particularly uniform and strong flow along the heat exchanger is achieved. The heat transfer is therefore particularly strong.

In particular, there is no need for a rib 86.2 in the longitudinal running area 84, since an elongated heat exchanger often already has a streamlined geometry, in particular in the longitudinal running area 84. Of course, it is also possible to provide only one of the ribs or only ribs in one of the areas.

In Fig. 8 A further arrangement of ribs 86 is shown, which are aligned along a flow course 88 caused by a disk, not shown. The embodiment of the Fig. 8 differs from that of Fig. 7 essentially by providing several inclined ribs 86.4, 86.5 and 86.7, 86.8 in the inlet and outlet areas 80 and 82, respectively, with different angles. In the flow direction therebetween, a rib 86.6 aligned along the longitudinal axis is provided in a longitudinal running area 84.

The ribs 86.4 to 86.8 are each arranged approximately parallel to the flow course 88, it being possible for the flow course 88 to be represented even better by a stepped arrangement than in FIG Fig. 7 . Nevertheless, their embodiment can be preferred, for example due to less manufacturing effort.

Also in Fig. 8 The ribs shown form a geometry which defines an essentially concentric ring path for the oil flow 88 with respect to the flow course 88 and the disk (not shown). The ribs can, for example, be arranged on an upper side and / or lower side of a heat transfer body. But you can also, for example, on an outside and / or an inside of an annular heat transfer body, for example be provided. It is therefore advantageously possible to provide generally flow-guiding, flow-supporting and / or geometries which oppose the flow with a particularly low resistance. This improves the flow rate and heat transfer. In principle, it is also conceivable, for example, to provide an actually circular rib or recess and / or projection.

Reference list

10th

Screw vacuum pump

12th

engine

14

Gear box

16

casing

18th

End shield

20

cover

22

inlet

24th

Outlet

26

Cooling pipe

28

Screw rotor

30th

Screw rotor

32

Groove

34

Immersion cooler

36

Waist

38

Screw profile

40

Screw profile

42

Synchronization gear

43

gear

44

casing

46

stator

48

Magnetic carrier

50

Potting body

52

circuit board

54

Washer

56

camp

58

Deflector

60

Piston ring carrier

62

first section

63

Screw axis

64

second part

66

third section

67

Suction area

68

camp

70

End shield

72

Cooling pipe

74

Heatsink

76

flange

78

Direction of rotation

80

Inlet area

82

Drain area

84

Longitudinal range

85

magnet

86

rib

88

Oil flow

Claims (13)

1. A vacuum pump (10), in particular a screw vacuum pump, comprising at least one rotor (28) which can be set into rotation to convey a process gas;
   an oil system for the lubrication and/or temperature control of the rotor (28) and/or of a transmission (42);
   one or more disks (54) which are arranged such that the respective disk (54) is immersed in an oil filling of the oil system in the operation of the vacuum pump and rotates with the rotor (28) and/or with a transmission element (43); and a heat exchanger (34) for the oil system which is arranged such that it is at least partly arranged in the oil filling in the operation of the vacuum pump (10),
   wherein the disk or disks (54) is/are configured and arranged to bring about, as a result of their rotation, an at least substantially unidirectional flow (88) in the oil filling at least in the region of the heat exchanger (34), characterized in that
   the vacuum pump (10) comprises a housing section (14) for the oil filling and the housing section (14) has an opening through which the heat exchanger (34) is introduced or can be introduced into and/or can be removed from the housing section (14).
2. A vacuum pump (10) in accordance with claim 1,
   characterized in that
   the heat exchanger (34) extends along a longitudinal axis and the disk (54) is arranged in parallel with the longitudinal axis so that the flow in the oil filling runs substantially along the heat exchanger (34).
3. A vacuum pump (10) in accordance with at least one of the preceding claims,
   characterized in that
   the heat exchanger (34) at least partly surrounds the disk (54).
4. A vacuum pump (10) in accordance with at least one of the preceding claims,
   characterized in that
   the vacuum pump (10) comprises two rotors (28, 30) which are arranged in parallel, which are coupled by a transmission and of which, in the region of the heat exchanger (34), only one carries at least one disk (54) for the rotation in the oil filling.
5. A vacuum pump (10) in accordance with at least one of the preceding claims,
   characterized in that
   the heat exchanger (34) is part of a temperature control system which comprises a heating device and/or a cooling device for the heat exchanger (34).
6. A vacuum pump (10) in accordance with at least one of the preceding claims,
   characterized in that
   the heat exchanger (34) has a heat transfer body (74) comprising an aluminum material and/or has at least one line (72) comprising a stainless steel for a heat exchange fluid.
7. A vacuum pump (10) in accordance with at least one of the preceding claims,
   characterized in that
   an opening for the heat exchanger (34) is at least substantially arranged at a lowest point of an inner space of a housing section (14).
8. A vacuum pump (10) in accordance with at least one of the preceding claims,
   characterized in that
   at least one magnet (85) is arranged at the heat exchanger (34).
9. A vacuum pump (10) in accordance with claim 8,
   characterized in that
   the disk (54) defines an inflow region (80), a longitudinal flow region (84) and/or an outflow region (82) at the heat exchanger (34) for the oil flow (88), with the magnet (85) being arranged in one of these regions.
10. A vacuum pump (10) in accordance with at least one of the preceding claims,
    characterized in that
    the heat exchanger (34) has a plurality of recesses and/or projections (86) which are at least substantially oriented along a flow progression (88) caused by the disk (54).
11. A vacuum pump (10) in accordance with claim 10,
    characterized in that
    the or some of the recesses and/or projections (86) are arranged obliquely with respect to a longitudinal axis of the heat exchanger (34).
12. A vacuum pump (10) in accordance with at least one of the preceding claims,
    characterized in that
    the geometry of the heat exchanger (34) and/or of a heat transfer body (74) of the heat exchanger (34) substantially defines an annular path concentric to the disk (54) for the oil flow.
13. A method of operating a vacuum pump (10), in particular a screw vacuum pump, comprising
    at least one rotor (28) which is set into rotation to convey a process gas; an oil system for the lubrication and/or temperature control of the rotor (28) and/or of a transmission (42);
    one or more disks (54) which are arranged such that the respective disk (54) is immersed in an oil filling of the oil system and rotates with the rotor (28) and/or with a transmission element (43);
    a heat exchanger (34) for the oil system which is arranged such that it is at least partly arranged in the oil filling; and
    a housing section (14) for the oil filling that has an opening through which the heat exchanger (34) is introduced or can be introduced into and/or can be removed from the housing section (14),
    wherein, as a result of their rotation, the disk or disks (54) bring about an at least substantially unidirectional flow (88) in the oil filling at least in the region of the heat exchanger (34).

Images