EP2423509A2 - Vacuum pump - Google Patents

Abstract

The vacuum pump (1) has shafts (4,5) having rotors (2,3) as pump units, a storage- or drive region (8,9) for the shafts and a suction chamber (7). Gas delivery units (12,13) are provided, which are designed for conveying a medium away from the storage- or drive region in the direction to the rotor or to the outlet of the suction chamber.

Description

The invention relates to a vacuum pump, in particular Wälzkolben-, claw or screw pump, with at least one rotor having a pumping device shaft, at least one bearing and / or drive region for the shaft and at least one pumping chamber, wherein in a pumping a medium by rotation of the Rotor is conveyed from an inlet of the pump chamber to an outlet of the pump chamber. In the case of the vacuum pump according to the invention, the pumping device serves to convey the medium from the inlet of the pumping chamber to the outlet of the pumping chamber. In particular, the invention relates to a vacuum-free and non-contact dry running in the suction chamber vacuum pump, further in particular with a final vacuum in the fine vacuum range of 10 ² Pa to 10 ^-2 Pa.

Numerous processes in research and industry require a vacuum, for example in the range of 10 ² Pa to 10 ^-2 Pa, which often also condensing and / or aggressive vapors or gases must be promoted. To create a vacuum in this range, liquid-sealed or lubricated vacuum pumps, such as oil-sealed rotary vane pumps, are often used. The use of such pumps, in which the pumped medium comes into contact with oil or other liquids, has numerous disadvantages.

For this reason, so-called dry vacuum pumps are used for conveying condensing and / or aggressive vapors or gases in the prior art, ie pumps in which the pumped media come into contact with any liquid.

One type of fine vacuum pumps are Roots pumps, also called Roots pumps, Roots pumps, for example, have two 8-shaped pistons, the non-contact, ie without sliding seals, in a suitably shaped housing synchronously to each other, thereby gas is conveyed from the inlet to the outlet.

With such an arrangement, compression ratios of about 10 to 30 can be achieved. For the fine vacuum generation therefore a backing pump or a multi-stage construction is required. A disadvantage of this design are the complex structure and tight mechanical tolerances that must be adhered to during manufacture and operation. In addition, Roots pumps are sensitive to condensates, aggressive media or particles.

The same applies to claw pumps, which, however, can achieve a compression ratio of about 50, so come up with a smaller number of stages than Roots pumps. Claw pumps also have noncontact synchronous running rotors. For smaller pumping speeds, however, the requirements for the gap dimensions are too high for an economical realization.

Another common type of oil-free fine vacuum pumps are so-called screw pumps. In screw pumps, two helical rotors abut contactlessly in a suitably shaped housing, with gas being delivered from the inlet to the outlet. The advantage of screw pumps in comparison to roots or claw pumps is the high possible compression, since screw pumps can be built up intrinsically in many stages, with each screw thread acting as a step. Screw pumps thus offer the possibility of achieving a deep end vacuum with only one pair of rotors. With only one rotor pair per shaft end, a so-called flying bearing of this pair of rotors is possible, i. H. the rotor pair is only supported on one side. This allows easy disassembly, for example, for maintenance and cleaning purposes, however, from the prior art screw pumps are known in which a bilateral bearing of the waves is provided with respect to the pump chamber.

The drive of the rotors in two-shaft pumps, such as Roots, claw and screw pumps, can be done by two synchronously running motors or by a means for driving and synchronizing the rotors from a single drive shaft, such as a gearbox.

If the bearings and the drive of the vacuum pump are in a gas-contacted area, this can be disadvantageous for many applications Often gases with a certain dust or vapor content or even corrosive gases and vapors must be promoted. Even pumping out containers filled with ordinary ambient air can cause moisture in the pump to condense. Also in many other applications contain the media to be pumped vapors. Even if they are not corrosive, they can lead to damage in a condensed form, for example, the bearings by the condensates wash out bearing grease and / or it comes to rust on the camps.

From the prior art it is known to use for conveying gases with dust and / or vapor content or for pumping corrosive gases and vapors pumps in which the one or more areas with bearings and drives are flushed with purge gas under pressure in the direction of the pumping chamber. This requires connection of purge gas with some overpressure to the pump by the user. However, such a pressurized gas is often not available, especially for smaller pump applications, such as in the laboratory or in mobile applications.

Alternatively, the drive region (s) can also be separated from the pump chamber by one or more shaft seals. However, such shaft seals must be run dry at this point, otherwise the lubricant could contaminate the vacuum area. However, dry running shaft seals have limited service lives.

Object of the present invention is a dry and non-contact in the pump chamber, d. h, without abrasive seals, working, compact and at the same time economical to manufacture and operate vacuum pump for the range of atmospheric pressure to fine vacuum to provide, with the media that contain condensable vapors or aggressive substances, can be promoted without it Damage to the pump comes.

The above object is achieved with a vacuum pump according to claim 1. The gas delivery device serves to keep away the gases and vapors conveyed by the vacuum pump as well as dusts contained therein from the storage and / or drive region. It is different from the actual one Pumping device or the rotor, which compresses within the pumping chamber and the medium from the inlet to the outlet of the pumping chamber promotes. The design differences existing between the actual pumping device or the rotor and the gas delivery device provided according to the invention lead to a different flow conductance and / or to a different compression ratio during operation of the pump. The pumping chamber in the medium-compressing element of the vacuum pump so the rotor, in particular designed as a screw, claw, rotary piston or Roots rotary piston, and inventively provided gas conveyor may be formed as separate components or in one piece. Preferably, the rotor and the gas delivery device are integrally integrated in the shaft. It is likewise possible to design the shaft, the rotor and the gas delivery device provided according to the invention as separate components or in one piece.

Preferably, no abrasive seal is provided between the pumping space and a storage and / or drive area.

In particular, in the case of the vacuum pump according to the invention, it is not necessary to supply a purge gas under overpressure to the bearing and / or drive region or to the region between the bearing and / or antiseb area and the suction chamber.

Preferably, a gas delivery device may be provided adjacent to a storage and / or drive region on the atmosphere or pressure side of the pumping chamber and designed to convey the medium counter to the conveying direction of the rotor and / or towards the outlet.

A gas delivery device may additionally or alternatively also be arranged adjacent to a storage and / or drive region on the suction side of the pumping chamber and designed to convey the medium in the conveying direction of the rotor and / or in the direction of the outlet.

The gas delivery device according to the invention is designed so that the pumped by the pumping medium can not or only in small quantities to reach the storage and / or drive area, In addition, an inventive Gas delivery device can be used to promote a medium that exits the pump chamber during the pumping operation of the vacuum pump and enters an area between the pump chamber and an adjacent storage and / or drive area, back into the pumping chamber and / or to the outlet.

The gas delivery device may be arranged in the region between a bearing and / or drive region for the shaft and the rotor. Further preferably, the gas delivery device is arranged within a pump chamber bounding the pumping chamber housing. In principle, the gas delivery device can also be arranged outside the pump chamber, in particular in the region between an adjacent bearing and / or drive region for the shaft and a pump chamber.

In a further preferred embodiment, the vacuum pump according to the invention for arranging bearing parts, shaft synchronization means and shaft drive means can have at least one common bearing and drive region on an atmospheric side of the suction chamber or on its pressure side. A corresponding bearing and drive region for the shaft can in principle also be provided on the suction side of the pump chamber. Preferably, no sliding seals between the pump chamber and the storage and / or drive area are present.

In a vacuum pump having a plurality of rotors having shafts, each associated with at least one bearing and / or drive region, preferably at least one gas delivery device is associated with each storage and / or drive region. In principle, a common gas delivery direction can also be provided for a plurality of shafts.

A vacuum pump according to the invention with two shafts can have a double-flow design such that the inlet is provided in the middle of the pumping chamber and the gas is sucked in the middle of the pumping chamber and conveyed to both sides, so that atmospheric pressure can be present at both ends of the pumping chamber. A two-shaft vacuum pump with a double-flow design can have bearing and / or drive parts for the shafts and the corresponding bearing and / or drive regions on one or both shaft ends associated provided according to the invention gas conveying devices and optionally have facilities for a purge gas.

In an alternative embodiment of a vacuum pump according to the invention with two shafts flying rotors may be provided at least in a pump chamber, wherein the waves are not stored on the suction side of this pump chamber.

A vacuum pump according to the invention with two shafts may be constructed in the manner of a multi-stage pump based on the Roots principle and / or the jaw principle. In these types of pumps, the "atmosphere side" refers to the atmosphere-compressing stage of the multi-stage arrangement. However, a vacuum pump according to the invention with two shafts is preferably a screw pump.

The gas delivery device provided in the vacuum pump according to the invention can be constructed in the manner of an integrated fan with at least one fan blade or in the manner of a fan compressor with at least one rotor or in the manner of a molecular pump, such as a Holweck stage. During the pumping process in the pumping chamber, an overpressure level can be achieved. The outlet of the vacuum pump according to the invention may also be connected to a conduit or other device, such as a condenser or a gas washing bottle, for the removal of pumped vapors and gases.

Depending on the amount of media pumped at the pump outlet, an overpressure of the order of magnitude of 1 to 50 mbar may arise. An overpressure of the same order of magnitude can also be created by suction of media having a high pressure level, for example, when sucked from a closed container in which overpressure prevails.

The gas delivery device must accordingly be able to build up a sufficiently high pressure to overcome the backpressure and to ensure that the conveyed media can not be pushed into the storage and / or drive area. For example, specially shaped Provided radial fan to produce a sufficiently high pressure level.

High speeds of vacuum pumps in the range of 3,000 to 25,000 rpm can be used to advantage. Alternatively, the gas delivery device may also be designed like a side channel blower, whereby high speeds are also advantageous here.

Preferably, the rotating elements of the gas delivery device, such as fan wheels or other rotors, directly from the shaft of the vacuum pump, in a vacuum pump with two shafts of one or both shafts, driven or are mounted on this or these.

The vacuum pump according to the invention may have a housing bounding the pumping chamber, wherein the gas conveying device between the rotor and an outer wall of the pump chamber housing, ie within the scoop. space, arranged and the shaft is guided through the housing through to the storage and / or drive area. In principle, the gas delivery device can also be arranged outside the actual pump chamber housing in the region between the pump chamber housing and the bearing and / or drive region.

In order to create a condensate drain, the pump chamber housing can have at least one drainage slope emerging from an opening in the housing as shaft passage for a shaft of the vacuum pump. The drainage slope may extend like a collar over the entire circumference of the shaft passage. If a fan wheel is provided as a further gas delivery device, the fan wheel on the side facing away from the rotor can be adapted to the inclination of the drainage slope. The well-near part of the gas conveyor or the fan and / or close to the shaft portion of the adjacent pump chamber may be arranged closer to the pump chamber on the side facing away from the pump chamber as the wave-distant part of the gas conveyor and the housing, so that condensates in the pump chamber not or only over can escape the gap between the shaft and the pump chamber.

If the vacuum pump according to the invention has two shafts each having at least one rotor, each shaft can be assigned at least one gas conveying device provided according to the invention, wherein the gas conveying devices can also cooperate as synchromesh for synchronizing the shafts. For example, synchronization of the two shafts can take place via fan wheels interacting as synchronous transmissions. The fan wheels may each have an outer toothing, wherein the toothings are in engagement and can cause a synchronization of the two shafts.

In an alternative embodiment of the invention, a suction device connected to the outlet of the pump chamber for sucking off the medium from the pump chamber is provided for solving the above-mentioned problem in a vacuum pump, in particular in addition to the gas conveyor described above. The suction device is preferably arranged outside the actual vacuum pump and connected to an outlet line, wherein the vapors and gases conveyed in the pump chamber are sucked out of the atmosphere-side region of the vacuum pump or via the outlet of the pump chamber. In particular, the suction device is designed for a sufficient pressure reduction at the outlet of the vacuum pump, so that it can not come to the outlet of the medium via shaft passages from the pump chamber into the storage and / or drive area.

If the suction device builds up sufficient delivery pressure, so that there is always a certain negative pressure at the outlet of the vacuum pump, it is basically also possible to dispense with an integrated gas delivery device of the type described above in addition to the actual pumping device, the protection of the bearing and / or Drive range can be done by sucked from the outside purge gas.

The suction device can be driven and / or mounted on the shaft of the vacuum pump, wherein, preferably, the shaft for driving the suction device is led out of the preferably atmosphere-side bearing and / or drive region on the side remote from the pump chamber,

For example, an integrated side channel blower can be provided as a suction device, which allows a pressure build-up of preferably more than 50 mbar. This blower can also serve as a supercharger for the vacuum pump according to the invention. For this purpose, the atmosphere-side region of the vacuum pump can be designed so that the fan at the same time sucks and compresses gases or vapors from the storage and / or drive region and also pumped media from the pumping chamber. The compressor may be provided on the outside of the vacuum pump according to the invention, for example on a free shaft end, and / or driven separately. The arrangement from the outside of the vacuum pump results, for example, in a side channel compressor, the advantage that the diameter of a rotor of the compressor is not limited to the rotor diameter of the vacuum pump.

A guided out of the storage and / or drive range wave can be used in both alternative embodiments of the invention described above, for example, by means of a patch conventional fan to provide a cooling air flow for cooling the vacuum pump according to the invention.

To further improve the protection of the storage and / or drive area. For example, a purge gas feed, in particular an air and / or nitrogen feed, from the environment into the area between the storage and / or drive region and the pump chamber and / or directly into the storage and / or drive region. The purge gas is preferably not supplied with overpressure, but sucked. If the gas admitted from the outside is ambient air, no external purge gas connection is required. In a preferred embodiment, purge gas adjacent to and / or directly in the storage and / or drive area, which adjoins the pumping chamber to a gas conveyor provided according to the invention, are admitted from the outside, so that the purge gas from the gas conveyor towards the pump chamber and / or Outlet is encouraged. If a suction device is provided for sucking off via the outlet of the pumping chamber, the flushing gas can also be sucked into the pumping chamber via a shaft feedthrough on account of the pressure reduction caused by the suction device at the outlet.

On the suction side of the vacuum pump, it is not absolutely necessary to provide a gas conveyor, since there is usually negative pressure during operation on the suction side of the vacuum pump, so that a purge gas from the outside usually without additional gas conveyor from the storage and / or drive area or the Area between the storage and / or drive area and the suction chamber is sucked into the suction chamber. By a Gasfördereitnichtung on the suction side, however, a purge gas is ensured in the pump chamber even at higher pressures on the suction side, wherein the volume flow of the purge gas is preferably very low, not or only slightly affect the final vacuum of the pump.

The flushing gas flow may also be adjustable by a user by means of a valve, which may apply to the pressure side and / or the suction side of the vacuum pump according to the invention. For example, the purge gas volume flow can be adjusted depending on the amount of dust or steam and the ultimate vacuum requirements. The control of the valve can also be done automatically depending on process parameters, such as the suction pressure, or time-dependent. A motor-operated valve can be used at the same time as purge gas valve after the end of the operation, which will be discussed further below.

In order not to jeopardize the (low) pressure level achievable during the pumping process, the volume flow of the purge gas which is supplied to the pump chamber must be limited. In the event that a purge gas is conveyed or sucked in by a gas delivery device and / or a suction device connected to the outlet from the storage and / or drive region in the direction of the suction chamber, the purge gas volume flow can be adjusted, for example by a suitable adaptation of purge gas channels through which the purge gas is guided between the storage and / or drive area and the pump chamber and / or the environment and / or adjusted by a suitable structural design of the gas conveyor and / or by at least one adjustable valve so that it is not or only to the purge gas a slight increase in pressure in the pump chamber comes.

If the purge gas flows through the bearing and / or drive region, cooling of a drive unit provided for driving the shaft can be effected by the purge gas. This is particularly advantageous when the drive unit is arranged together with bearings of the shaft in a common storage and drive space.

In a further embodiment of the invention is provided for solving the above-mentioned problem that a medium and / or purge gas is sucked through at least one arranged between a storage and / or drive area and the adjacent pump chamber intermediate space. For suction, the housing may, for example, have a suction channel, which is connected to a suction device and opens into the intermediate space. It is understood that the embodiment described here can also be combined with one of the embodiments described above.

In a vacuum pump according to the invention with two rotors having synchronously rotatable rotors in the opposite direction, a synchronization of the shafts can take place by means of a magnetic gear. In this case, the synchronization takes place by contactless passing past discs or the like, which are held in synchronization by magnetic forces due to appropriate magnetization or applied magnets. Preferably, it is possible to apply alternately poled permanent magnets to the disks in mirror image form over the circumference. Since the two discs do not touch, the magnetic transmission runs quietly, wear-free and therefore also lubricant-free.

If such a magnetic gear is surrounded by suitably arranged coils for generating magnetic fields and the coils are energized suitably according to the position of the magnetized disks, a synchronous two-shaft drive is obtained analogous to a brushless DC drive or synchronous motor, wherein the magnetized Slices of the gearbox serve as motor rotors. By way of example, a motor stator which surrounds the disks only in regions, in particular in a half to three-quarter circle, may be provided. As a result, the drive is integrated into a magnetic gear in the form of a brushless two-shaft synchronous motor. Preferably, the combined drive and synchronization device is mounted in the vicinity of the shaft bearings, drive parts for the shafts and bearing parts for shaft mounting being arranged in a common bearing and drive region. In this way, a compact and completely non-contact arrangement is obtained, with the exception of the bearing grease no lubricant can be provided in the drive area. "Synchronous" in the context of the invention in this context refers both to the rotation of the contactless passing past discs with respect to the externally applied magnetic field and to the rotation of the discs relative to each other.

Particularly preferably, such a two-shaft synchronous drive can be used if no sliding seal is provided between the pump chamber and an adjacent bearing and / or drive region. The two-shaft synchronous drive can - unlike a drive based on two separate, electronically synchronized motors - work completely lubricant-free, but allows a much more compact design than the latter. The use of a two-shaft synchronous drive in the vacuum pump according to the invention thus contributes to a small construction volume of the vacuum pump. The actual storage area may be sealed separately, with integrated sealants in the bearings preventing the escape of lubricants from the bearings. The gas delivery device provided in the vacuum pump according to the invention also protects the storage and / or drive area from the pumped media. Since in a two-shaft synchronous drive lubricant thus does not have to be prevented from escaping from the drive region and pumped media are prevented by the action of the gas conveyor at the entrance to the drive range, a construction of the vacuum pump according to the invention is completely without sliding seals between the pump chamber and an adjacent storage and / or drive range also for applications with aggressive dusts, gases and vapors possible. This is extremely advantageous, since thus a completely non-contact and thus wear-free and maintenance-free drive system is created.

Is a synchronization of the waves provided by a magnetic transmission, meshing gears of an inventively provided Gas conveyor as emergency gear in case of failure of the magnetic gear cooperate. For example, fan wheels of the gas conveying devices may have an external toothing extending over the circumference of the fan wheels. Preferably, however, such gears of the gas delivery devices are designed such that it comes only in case of failure of the magnetic transmission to a contact of the gears. As a result, in the normal operating state of the vacuum pump (when synchronizing only via the magnetic gear), the wear on the gears and the development of running noises are reduced or eliminated. In principle, emergency gears may also be provided as separate components, which are arranged in the vicinity of the discs of the magnetic transmission.

For applications with non-corrosive gases and vapors, the wetted parts of the vacuum pump according to the invention may consist, for example, of aluminum, steel or suitable plastics. For corrosive gas and vapor applications, the surfaces of the wetted parts may be coated with correspondingly chemically resistant coatings such as fluorine-based plastics such as ethylene-tetrafluoroethylene polymers (ETFE), ethylene-chlorotrifluoroethylene (ECTFE) polymers, perfluoroalkoxy polymers (PFA), or similar materials, or consist of chemically resistant solid materials such as stainless steel or chemically resistant plastics, such as polyphenylene sulfides (PPS), ECTFE or the like. In a preferred embodiment, the rotors of the vacuum pump according to the invention of a plastic, which is much lighter than the steel materials commonly used. This reduces any existing imbalances, which vibrations, which can lead to oscillations of the waves and thus collisions of the rotors with each other or with the housing can be reduced. In addition, such plastics such as PPS or polyetheretherketones (PEEK) have a high chemical resistance and have, if necessary by additives to be reinforced, advantageous tribulogical properties that can limit damage in case of collisions of the rotors. Finally, plastic rotors can be injection-molded onto the rotor shafts. In this case, for example, a fan blade of a gas conveyor easy with molding, which allows a cost-effective, with the rotors cinteilige production.

If (minor) contamination of the storage and / or drive area with conveyed corrosive media can not be excluded, especially at standstill of the vacuum pump according to the invention, more particularly if a rinse is not provided after the end of operation, and the storage and / or drive range be designed corrosion resistant. In this connection, ball bearings may be provided, for example, of stainless steel or ceramic, in particular using perfluoropolyether (PFPE) lubricants, and PPS or PEEK ball cages, where the shaft may be coated with suitable media resistant materials. If the drive is integrated directly into the storage area, it must also be protected by appropriate coatings. In the case of a two-shaft synchronous motor with magnetic gear, this can be done by coating the magnetic disks and the stator laminations, or it can be a thin, chemically resistant, gas-tight partition between the coated magnetic disks and the motor stator are provided.

The pumping chamber can be connected to a purge gas line, wherein the purge gas line can open into the pump chamber in the region of the inlet of the pump chamber. In principle, however, it is also possible for the purge gas line to pass through the housing of the vacuum pump according to the invention at another point and to open into the pump chamber. Incidentally, a suction line may be connected to the inlet of the suction chamber for drawing in a medium to be compressed. At least one valve can be provided in the purge gas line and / or in the intake line, wherein the valve control and the control of a drive unit for the shaft of the vacuum pump according to the invention can be effected by means of a common control device.

A particularly preferred embodiment of the invention provides that an inlet or suction line opening into an inlet of the suction chamber and / or a purge gas line connected to the suction chamber and / or the suction line are provided, wherein the suction line is an intake valve and the purge gas conduit comprises a purge gas valve and wherein a control means is provided for controlling the valves and for controlling a drive unit for the shaft. For flushing the vacuum pump according to the invention during a shutdown process, the controller is preferably designed such that at the end of a pumping operation initially closes the inlet valve and the pumping or rotation of the rotor shaft (s) for a limited time, for example, 1 to 5 min, on is operated to flush out gases and vapors located in the pump chamber with purge gas when the purge gas valve is open. The rotation of the rotor shaft (s) takes place optionally at reduced speed. After a certain time, the pumping process or the rotation of the rotor shaft (s) is terminated and the purging gas valve is closed.

The inlet valve and / or the purge gas valve are preferably actuated by a motor. The switching of the valves can be done manually by a user or automatically depending on process parameters, such as the suction pressure, or even time-dependent. The pump may in the event of a fault condition, such as during a power failure, and at the end of a pumping operation by closing the inlet valve vacuum-tight shutdown, wherein the inlet valve remains closed even after the end of the purge operation, when the pump drive is turned off.

In addition, a check valve can be arranged in an outlet line of the vacuum pump connected to the outlet of the pump chamber in order to prevent a periodic backflow of grass into the pump chamber during the pumping operation and to ensure a quiet pumping operation.

In particular, there are a large number of possibilities for embodying and developing the vacuum pump according to the invention. For this purpose, reference is made on the one hand to the dependent claims and on the other hand to the following detailed description of preferred embodiments of the invention with reference to the drawings.

The features described above and the features described below with reference to the drawing may, if necessary, be combined with one another, even if this is not expressly described in detail. in the

Incidentally, each of the described features may have their own meaning, especially in connection with the features of the preamble of claim 1.

Fig. 1

eine schematische Querschnittsansicht einer ersten Ausführungs-form einer erfindungsgemäßen Vakuumpumpe,

Fig. 2a, 2b

Lüfterräder der in Fig. 1 dargestellten Gasfördereinrichtungen,

Fig. 3

eine zweite Ausführungsform einer erfindungsgemäßen Vaku-umpumpe in einer schematischen Querschnittsansicht,

Fig. 4

eine dritte Ausführungsform einer erfindungsgemäßen Vakuum-pumpe in einer schematischen Querschnittsansicht und

Fig. 5

eine schematische Darstellung einer effindungsgemäßen Vaku-umpumpe, bei der eine Spülung der Pumpe mit einem Spülgas möglich ist.

In the drawing shows

Fig. 1

a schematic cross-sectional view of a first embodiment of a vacuum pump according to the invention,

Fig. 2a, 2b

Fan wheels of in Fig. 1 illustrated gas conveyors,

Fig. 3

A second embodiment of a vacuum pump according to the invention in a schematic cross-sectional view,

Fig. 4

a third embodiment of a vacuum pump according to the invention in a schematic cross-sectional view and

Fig. 5

a schematic representation of a vacuum according to the invention in which a purging of the pump with a purge gas is possible.

In Fig. 1 is a dry-running vacuum pump 1 with two rotors 2, 3 shown. These sit on shafts 4, 5. In addition, a pump chamber 6 is provided, which defines the pump chamber 7 together with the two rotors 2, 3. The rotors 2, 3 are shown only schematically and, for example, in a Roots-, claw or screw design of the vacuum pump 1 are in meshing engagement with each other. The outer circumference of the rotors 2, 3 runs at a small distance, but without contact on the wall of the suction chamber 7 over. The rotors 2, 3 are guided axially parallel by the shafts 4, 5. The shafts 4, 5 are mounted in bearing and / or drive areas 8, 9 and are driven synchronously. The bearing and / or drive regions 8, 9 are arranged in housing parts 8a, 9a.

With synchronous rotation of the shafts 4, 5 and thus of the rotors 2, 3, a gaseous medium from an inlet 10 to an outlet 11 of the suction chamber 7 promoted. The rotors 2, 3 form the actual pumping device of the vacuum pump 1 and serve to promote the medium and / or to compress. The outlet 11 may, for example, be at atmospheric pressure, while at the inlet 10 with driven shafts 4, 5, ie when the rotors 2, 3 rotate, a negative pressure is created.

The pump chamber 6 has shaft passages 14 through which the shafts 4, 5 are guided into the bearing and / or drive regions 8, 9. Between the suction chamber 7 and the storage and / or drive regions 8, 9 no abrasive sealing means are provided here, so that the suction-side storage and / or drive region 8 is at a low pressure level under normal operating conditions of the vacuum pump 1, while the pressure is in the region of pressure-side bearing and / or drive area 9 corresponds to the ambient pressure.

In the illustrated vacuum pump 1, grass conveyers 12, 13 are provided between the rotors 2, 3 and the storage and / or drive areas 8, 9. These each generate a gas flow in the direction away from the bearing and / or drive regions 8, 9 and in the direction of the rotors 2, 3 and / or the outlet 11 of the suction chamber 7. The gas conveying devices 12, 13 are within the pump chamber housing 6 between the adjacent storage and / or drive area 8, 9 on the one hand and the rotors 2, 3 on the other hand arranged.

Incidentally, the gas conveying devices 12, 13 are arranged on the shafts 4, 5 and are driven by these. During operation of the vacuum pump 1, dusts, gases and vapors are thus conveyed back from the gas conveying devices 12, 13 in the direction of the rotors 2, 3 and / or to the outlet 11, so that the bearing and / or drive regions 8, 9 are preceded by these dusts , Gases and vapors are protected. The gas conveying devices 12, 13 prevent media conveyed in the pumping chamber 7 and thus gases, dusts, vapors from being forced outwards through the shaft passages 14 into the surrounding area of the vacuum pump 1 and / or into an adjacent bearing and / or drive area 8, 9. The protection of the storage and / or drive regions 8, 9 can be further enhanced if purge gas, in particular

Ambient air, supplied from the outside and is conveyed by the gas conveying means 12, 13 in the suction chamber 7 and the outlet 11.

Since a vacuum level is formed during operation of the vacuum pump 1 in the suction-side region near the inlet 10 and thus also in the adjacent bearing and / or drive region 8, preferably no or only a very small supply of an external flushing gas is provided here. Apart from the possibility described above, a low-dose and optionally adjustable purge gas flow to the storage and / or drive area 8 and / or a region 15 between the storage and / or drive area 8 and the pump chamber 7, the housing part 8a for the camp - And / or drive portion 8 on the suction side of the vacuum pump 1 is substantially gas-tight manner connected to the pump chamber housing 6.

It is not shown that the gas delivery device 12 does not necessarily have to be provided on the suction side of the vacuum pump 1. Basically, it may be possible due to the prevailing negative pressure, the suction-side storage and / or drive area 8 only by a limited and optionally adjustable purge gas flow, the storage and / or drive area 8 and / or the area 15 is supplied, before gases and vapors from the S chöpfraum 7 to protect.

The pressure-side region of the vacuum pump 1 near the outlet 11 and the adjacent bearing and / or drive region 9 are under atmospheric pressure. Therefore, it is not necessary that the housing part 9a for the storage and / or drive region 9 is connected in a gastight manner to the pump chamber housing 6. Here the purge chamber 7 via channels 14a and the shaft passages 14 purge gas, in particular ambient air, are supplied to ambient pressure. The channels 14a may be externally provided with a gas connection. Additionally and / or alternatively, it is also possible to suck purge gas directly through the bearing and / or drive region 9, the housing part 9a having to have a corresponding inlet opening (not shown) for the purge gas.

Fig. 1 shows a vacuum pump 1 with an inlet 10 on one side of the suction chamber 7 and with an outlet 11 on the other side of the Pump chamber 7. It is not shown that the vacuum pump 1 can also have a double-flow construction in which the inlet in the middle region of the suction chamber 7 and an outlet at both ends of the suction chamber 7 corresponding to the position of the inlet 10 and the outlet 11 at the in Fig. 1 illustrated vacuum pump 1 are provided. In this case, atmospheric pressure prevails at the two outlets.

In the Fig. 2a and 2b exemplary embodiments of the gas conveying devices 12, 13 are shown as fans with fan wheels 16, 17. The fan wheels 16, 17 are arranged on the shafts 4, 5 and driven by them. According to Fig. 2a has the fan 16 straight wing 18. As a result, the funded by the fan 16 volume flow direction of rotation is independent. According to Fig. 2b For example, the fan 17 may also have curved wings 19, so that an efficient gas delivery is possible, but the conveying direction is defined by the predetermined direction of rotation of the fan 17.

In Fig. 3 is a vacuum pump 1 with flying rotors 2, 3, so with only one-sided storage of the shafts 4, 5, shown. Structurally identical and / or functionally identical components are provided with the same reference numerals.

According to the in Fig. 3 illustrated embodiment, no storage and / or drive area 8 is provided on the suction side, so that on the suction side no bearing grease or the like can be released.

Analogous to the in Fig. 3 illustrated design with flying rotors 2, 3, the vacuum pump 1 and shafts 4, 5, each having at both shaft ends rotors 2, 3. In this case, the shafts 4, 5 project through the housing part 9a of the bearing and / or drive region 9 Fig. 3 down out. Rotors 2, 3 are then also provided on the shaft ends that protrude downwards, which are arranged in a further pumping space 7 (delimited by a further pump chamber housing 6). It is self-evident that gas conveying devices 13 can also be provided on the side of the further pumping chamber 7 in order to protect the bearing and / or drive region 9 on this side from the penetration of dusts, gases and vapors from the further pumping chamber 7. The two Schöpfräume 7 of previously described arrangement can be connected in series or in parallel with their pairs of rotors, which has a corresponding effect on the pressure conditions (vacuum or atmospheric pressure) and also effects on a possible purge gas supply (purge gas supply provided or no or only very small purge gas) may have.

The schematic sectional view in Fig. 4 shows a preferred embodiment of the vacuum pump 1, in which the rotors 2, 3 are cantilevered. The shafts 4, 5 are synchronized by a magnetic gear 20, wherein the drive of the shafts 4, 5 is designed as an integrated two-shaft synchronous motor.

The bearing and drive region 9 has bearing parts 22, 23 for supporting the shafts 4, 5, wherein the bearing parts 22, 23 may be formed as ball bearings. Between the bearing parts 22, 23 discs 24, 25 are mounted with permanent magnets on the outer circumference, wherein the permanent magnets are mirrored in mirror image over the circumference alternately. Due to the mutual forces of the permanent magnets, the discs 24, 25 and thus the shafts 4, 5 synchronize. The discs 24, 25 run at a small distance from each other, so that a contact-free magnetic transmission 20 is formed. The discs 24, 25 are radially outwardly surrounded by a motor stator 26, which consists of laminated cores with windings, which are energized by a control electronics, not shown, suitable to put the magnetized discs 24, 25 in a synchronous rotation. The arrangement shown thus forms a two-shaft synchronous motor. The term "synchronous" refers both to the rotation of the discs 24, 25 with respect to the externally applied magnetic field and to the rotation of the discs 24, 25 relative to each other.

Not shown is that the gas conveying means 13 have an external toothing and can be in mutual, non-contact engagement to serve as an emergency transmission in the event of failure of the magnetic gear 20, formed by the discs 24, 25.

The pump chamber housing 6 is in this example with the housing part 9a, which limits the storage and drive area 9, in a flow connection.

During operation of the vacuum pump 1 is ensured by the action of the gas conveying means 13 that no dusts, gases and vapors from the suction chamber 7, d. H. the region of the vacuum pump 1, in which the rotors 2, 3 are arranged, can flow into the bearing and drive region 9. In order to support this effect, an externally supplied flushing gas flow 21 can be conveyed by the gas conveying devices 13 out of the storage and drive region 9 in the direction of the pumping chamber 7. For this purpose, the housing part 9a channels 27, 28, wherein the channels 28 are connected in flow conduction with the shaft passages 14. By the purge gas, the storage and drive area 9 is very effectively protected from dusts, gases and vapors from the pump chamber 7, wherein the purge gas 21 in addition to cooling the drive of the shafts 4, 5, formed by the discs 24, 25 and the stator 26th , contributes. At the inlet of the purge gas channel 27 may preferably be provided a gas connection, so that an inert gas or other purge gas can be supplied, if the supply of ambient air is not desired as purge gas.

In principle, it is additionally and / or alternatively also possible for purge gas to be sucked in directly from the outside and to enter the suction chamber 7 via the shaft passages 14. This is especially true if the purge gas is not to flow through the bearing and drive area 9. In this case, purge gas channels can directly connect the outer region or the environment of the vacuum pump 1 with the shaft passages 14. In addition, an external gas connection may be provided for the supply of an inert gas. In addition, external filters may be provided to prevent the entry of dusts or the like with the purge gas.

How to get out Fig. 4 results, the pump chamber housing 6 forming part of the vacuum pump 1 may have from the shaft passages 14 outgoing slopes 26, which serve as condensate drain. The side facing away from the pumping chamber 7 sides of the gas conveying means 13 and the adjacent part of the pump chamber housing 6 are formed so that in each case the shaft-near part closer to the suction chamber 7 is located as the wave-distant part. This prevents liquid condensates from flowing from the pump chamber 7 into the storage and drive region 9, regardless of the installation position of the vacuum pump 1.

For all alternative embodiments described above, it holds that the gas delivery devices 12, 13 also outside the pumping chamber 7, d. H. can be arranged outside of the pump chamber 7 limiting the pump chamber 7, namely between the pump chamber housing 6 and an adjacent storage and / or drive area 8, 9th

According to Fig. 5 a purge of the vacuum pump 1 may be provided with a purge gas at the operating end. For this purpose, a suction line 30 opening into the inlet 10 of the suction chamber 7 and a purge gas line 31 connected to the suction chamber 7 are provided, wherein the suction line 30 identifies a suction valve 32 and the purge gas line 31 a purge gas valve 33 and a control device 34 for operating the valves 32 , 33 is provided, which also controls the drive of the shafts 4, 5. The valves 32, 33 are driven by a motor or electromagnetically. In the illustrated embodiment, the purge gas line 31 opens into the suction line 30 between the intake valve 32 and the inlet 10 into the suction chamber 7. Basically, the purge gas line 31 also open directly into the suction chamber 7.

The control device 34 is designed such that, at the end of a pumping operation, the intake valve 32 is initially closed. Subsequently, the purge gas valve 33 is opened, which leads to the entry of purge gas into the pump chamber 7. The shafts 4, 5 are driven further in this flushing process, possibly at a reduced speed. After a certain time, the rotation of the shafts 4, 5 is stopped and the purge gas valve 33 is also closed.

In addition, a check valve 35 may be arranged in an outlet line 36, which opens into the outlet 11 of the vacuum pump 1. As a result, noise reduction during pump operation can be achieved. In addition, mufflers or gas deflections may be provided to further reduce the noise during pump operation.

All features of the illustrated embodiments may be combined as desired, although not described in detail.

Claims (15)

Vacuum pump (1) with at least one shaft (4, 5) having a rotor (2, 3) as pumping device, at least one bearing and / or drive region (8, 9) for the shaft (4, 5) and at least one pumping chamber ( 7), wherein during a pumping operation a medium is conveyed by rotation of the rotor (2, 3) from an inlet (10) of the pumping chamber (7) to an outlet (11) of the pumping chamber (7),
characterized,
in that at least one gas delivery device (12, 13) is provided, and in that the gas delivery device (12, 13) moves away from the storage and / or drive region (8, 9) in the direction of the rotor (2, 3) and / or to convey the medium Outlet (11) of the pump chamber (7) is formed. Vacuum pump according to claim 1, characterized
in that the gas delivery device (12, 13) is arranged between the bearing and / or drive region (8, 9) for the shaft (4, 5) and the rotor (2, 3), wherein, preferably, the gas delivery device (12, 13 ) is arranged within a suction chamber housing (6) delimiting the suction chamber (7). Vacuum pump according to claim 1 or 2, characterized
that a gas conveying device (13) only at the outlet (11) of the suction chamber (7) side facing the vacuum pump is provided, and
that at the inlet (10) of the pump chamber (7) facing side of the vacuum pump, preferably only a purge gas flow is supplied. Vacuum pump according to one of the preceding claims, characterized
in that a fan with at least one fan wheel (16, 17) is provided as gas delivery device (12, 13). Vacuum pump according to one of the preceding claims, characterized
in that the gas delivery device (12, 13) is driven and / or mounted on the shaft (4, 5) of the vacuum pump. Vacuum pump according to claim 2 and optionally one of claims 3 to 5, characterized
is that the grass conveyor (12, 13) between the rotor (2, 3) and an outer wall of the pump chamber housing (6) and the shaft (4, 5) through the pump chamber housing (6) guided. Vacuum pump according to claim 6, characterized
in that the pump chamber (6) has at least one outlet runner (29) for a condensate discharge from a shaft duct (14), preferably the sides of the gas conveyor (13) remote from the pump chamber (7) and the adjacent part of the pump chamber (6) are formed, that in each case the shaft near part closer to the suction chamber (7) than the shaft remote part. Vacuum pump according to one of the preceding claims, characterized
in that two shafts (4, 5) each having at least one rotor (2, 3) are provided, each shaft (4, 5) being associated with at least one gas conveying device (12, 13), and wherein, preferably, the gas conveying devices (12, 13) as a synchronous transmission for a synchronization of the shafts (4, 5) cooperate. Vacuum pump according to one of the preceding claims, characterized
that a purge gas supply in the region between the bearing and / or drive region (8, 9) and the pump chamber (7) and / or directly into the storage and / or driving portion (8, 9) is provided. Vacuum pump (1) with at least one shaft (4, 5) having a rotor (2, 3) as pumping device, at least one bearing and / or drive region (8, 9) for the shaft (4, 5) and at least one pumping chamber ( 7), wherein during a pumping operation a medium is conveyed by rotation of the rotor (2, 3) from an inlet (10) of the pumping chamber (7) to an outlet (11) of the pumping chamber (7),
in particular according to one of the preceding claims,
characterized,
in that the medium and / or flushing gas can be sucked away by means of a suction device connected to the intermediate space (14a, 15) via a gap (15, 14a) arranged between the storage and / or drive region (8, 9) and the pumping chamber (7). Vacuum pump according to one of the preceding claims, characterized
in that two shafts (4, 5) synchronously with each other in the opposite direction rotatable rotors (2, 3) and a two-shaft synchronous motor are provided for a magnetic drive and for a magnetic synchronization of the shafts (4, 5). Vacuum pump according to claim 11, characterized
in that the two-shaft synchronous motor and bearing parts (22, 23) for shaft mounting of the two shafts (4, 5) are arranged in a common bearing and drive region (9). Vacuum pump according to one of the preceding claims, characterized
in that a suction line (30) opening into the inlet (10) of the suction chamber (7) is connected to a suction valve (32) and / or a purge gas line (31) connected to the suction chamber (7) and / or to the suction line (30) Purge gas valve (33) are provided, and
in that a control device (34) is provided for the valves (32, 33). Vacuum pump according to claim 13, characterized
in that the control device (34) is coupled to a further control device for the drive unit of the shafts (4, 5). Vacuum pump according to one of the preceding claims, characterized
in that the vacuum pump is a rolling-piston, claw or, preferably, a screw pump.

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