EP2549113A2 - Magnetic rotor and rotation pump with a magnetic rotor - Google Patents

Abstract

The rotor (1) has a permanent magnet (8) sheathed within an outer encapsulation (6) by a metal casing (7), where the rotor is encapsulated by the encapsulation. The encapsulation comprises fluoridated hydrocarbon. The permanent magnet is connected with the metal casing in a form- and/or force-fit manner. The metal casing is connected with the encapsulation in a form- and/or force-fit manner. A recess (9) is formed between the permanent magnet and the metal casing. A thermal compensation unit (10) compensates different thermal expansions of the metal casing and/or the permanent magnet. An independent claim is also included for a rotary pump.

Description

The invention relates to a magnetic rotor for a rotary pump, as well as system components, in particular a rotary pump with a magnetic rotor according to the preamble of the independent claims 1 and 7.

For special applications, magnetically mounted rotary pumps have prevailed in the art, in which an impeller is suspended in the interior of a preferably completely closed pump housing by magnetic forces and driven by a rotating field which is generated by a stator often arranged outside the pump housing. Such pumps are particularly advantageous for those applications in which the fluid to be pumped must not be contaminated, for example for conveying biological fluids such as blood or highly pure fluids such as ultrapure water.

In addition, such rotary pumps are suitable for pumping aggressive liquids that would destroy mechanical bearings in a short time. Therefore, such rotary pumps are particularly preferably used in the semiconductor industry, for example for conveying mechanically aggressive fluids when processing a surface of semiconductor wafers. As an important example here chemical-mechanical polishing processes (CMP, chemical-mechanical planning) called. In such processes, a suspension, commonly referred to as a slurry, typically consists of very fine solid particles and a liquid on a rotating wafer applied and serves there for polishing or lapping the very fine semiconductor structures. Another example is the application of photoresist to the wafer, or the roughening of surfaces of computer hard disks to prevent sticking of the read / write heads by adhesion forces, for example by van der Waals forces.

For other highly aggressive substances magnetically levitated rotary pumps are preferably used in practice. For example, in semiconductor manufacturing for pumping highly aggressive chemicals such as sulfuric acid (H ₂ SO ₄ ), which often have to be provided even at elevated temperatures, eg at 150 ° C to 200 ° C or even higher. Another typical, very aggressive acid is phosphoric acid (H ₃ PO ₄ ), which in certain applications must be pumped reliably at temperatures up to 160 ° C or even higher. But also hydrochloric acid (HCl), hydrofluoric acid (HF), nitric acid (HNO ₃ ), acetic acid (CH ₃ COOH) or ammonium fluoride (NH ₄ F ₂ ). In this case, mixtures such as sulfuric acid and ozone (H ₂ SO ₄ with O ₃ ), sulfuric acid with hydrogen peroxide (H ₂ SO ₄ with H ₂ O ₂ ) or, for example, sulfuric acid with hydrofluoric acid and nitric acid (H ₂ SO ₄ with HF and HNO ₃ ) often in use.

It is known that certain fluorinated hydrocarbons show a certain resistance to chemically aggressive substances, in particular to the abovementioned acids. Therefore, it is also known, e.g. To provide rotor rotors of bearingless pumps with encapsulations of fluorinated hydrocarbons in order to protect the inside of the rotor permanent magnet as possible from the harmful effects of aggressive acids or acid mixtures.

However, the fluorinated hydrocarbons very often do not form a sufficient barrier to gaseous constituents of the chemicals. For example, an encapsulation made of a fluorinated hydrocarbon has only a very limited barrier effect against ozone (O ₃ ), for example in a too pumping mixture of sulfuric acid and ozone (H ₂ SO ₄ with O ₃ ) may be contained in substantial amounts.

Diffuses e.g. Ozone in sufficient amount by the fluorinated hydrocarbon encapsulation to the permanent magnet inside the rotor, this can lead to a very serious damage to the permanent magnet in the rotor, the permanent magnet can, for example. really inflate and blow up the rotor in the worst case.

It goes without saying that these negative effects are intensified even more at elevated temperatures, not least because, as is generally known, at elevated temperatures, the diffusion processes are increasingly massively accelerated.

In contrast, substances that form a better diffusion barrier are very often not resistant to the extremely aggressive acids, especially not at elevated temperature. So if you try to use Rotorverkapselungen from a material to another material than fluorinated hydrocarbons, these encapsulations are attacked very quickly by the aggressive acids, the encapsulant material can be partially dissolved or dissolved by the acids, which then as an impurity in the Pumping fluid passes and elsewhere in the process can develop a harmful effect.

If an encapsulation contains, for example, a metal, the acids can be used to dissolve metal ions which, as a component of the fluid to be pumped, can then have an effect on subsequent work processes. This can lead to catastrophic consequences, for example, in applications in the semiconductor industry, since the dissolved metal ions can alter the doping of the semiconductors to be treated in an uncontrolled manner even in very low concentrations in the fluid, thus rendering the semiconductor products completely unusable in the worst case. Of course, analog problems can also occur with regard to the pump housing. For example, if the interior surfaces of the pump housing are protected by a layer of fluorinated hydrocarbons, gaseous components may still diffuse through, which then destroy the stator over time.

It is therefore an object of the invention to provide a magnetic rotor for a rotary pump in which a provided inside the rotor permanent magnet for a sufficiently long life against the harmful effects of liquid and gaseous or dissolved in the form of ions substances of a fluid to be pumped is protected, so that the rotor must be replaced less frequently. In addition to be created by the invention, a rotary pump, in particular canned motor pump, which is adequately protected analogously to the inventive rotor against the aforementioned and known from the prior art harmful influences. In particular, a sufficient protection against aggressive acids with gaseous components, even for use at high temperatures to be created.

The objects of the invention solving these objects are characterized by the features of independent claims 1 and 7.

The dependent claims relate to particularly advantageous embodiments of the invention.

The invention thus relates to a magnetic rotor for a rotary pump, wherein the rotor for driving a fluid in a pump housing within a stator of the rotary pump is magnetically non-contact drivable and storable, and the rotor is encapsulated by means of an outer encapsulation comprising a fluorinated hydrocarbon. According to the invention, the rotor within the encapsulation comprises a permanent magnet encased in a metal jacket, the metal jacket comprising at least one metal Group of elements consisting of tantalum, niobium, zirconium, titanium, hafnium, gold, platinum, palladium, osmium, iridium, ruthenium and rhodium.

The permanent magnet of the rotor of the present invention is thus doubly encapsulated: An inner metal jacket encloses the permanent magnet of the rotor substantially completely, more preferably, the permanent magnet is gas-tightly enclosed by the metal shell. The metal shell in turn is inside an outer encapsulation of a fluorinated hydrocarbon. In this case, the metal sheath may preferably be completely encased directly by the encapsulation or, depending on requirements, a further material may be provided between the metal sheath and the outer encapsulation, for example to adapt the geometry, mass or other parameters of the rotor to particular requirements. Accordingly, the permanent magnet may also be enclosed directly by the metal sheath or there may be another material between metal sheath and permanent magnet, e.g. serves as a thermal compensation means for compensating different thermal expansions of the metal shell and / or the permanent magnet. Of course, for this purpose, a corresponding distance in the form of a gap between the metal shell and the permanent magnet can of course also be provided.

Characterized in that the permanent magnet is double-encapsulated by the metal shell and the outer encapsulation, the permanent magnet is at the same time, for example, against aggressive liquids such as sulfuric acid (H ₂ SO ₄ ), even at elevated temperatures, for example at 150 ° C to 200 ° C or even protected at higher temperatures. These are shielded from the permanent magnet by the outer fluorinated hydrocarbon encapsulation. But any existing gaseous component such as ozone, which may also be present in the aggressive liquid chemical, is effectively shielded. The shield possibly Existing gaseous components or ionic constituents of the acid, which are not or only insufficiently retained by the outer encapsulation and diffuse through the outer encapsulation into the interior of the rotor, are prevented at the latest by the metal jacket surrounding the permanent magnet.

It has been found that the permanent magnet of a rotor according to the invention even against very aggressive acids such as phosphoric acid (H ₃ PO ₄ ), which must be pumped reliably in certain applications at temperatures up to 160 ° C or even higher, but also hydrochloric acid (HCl) , Hydrofluoric acid (HF), nitric acid (HNO ₃ ), acetic acid (CH ₃ COOH) or ammonium fluoride (NH ₄ F ₂ ) and can be reliably shielded against other chemically aggressive substances. In this case, even mixtures such as mixtures of sulfuric acid and ozone (H ₂ SO ₄ with O ₃ ), sulfuric acid with hydrogen peroxide (H ₂ SO ₄ with H ₂ O ₂ ) or, for example, sulfuric acid with hydrofluoric acid and nitric acid (H ₂ SO ₄ with HF and ENT ₃ ) or other chemically highly aggressive mixtures can be effectively shielded.

The service lives of the rotors or the service lives of plant components according to the invention with an outer layer of fluorinated hydrocarbon and an underlying second layer of a metal of the group of elements consisting of tantalum, niobium, zirconium, titanium, hafnium, gold, platinum , Palladium, osmium, iridium, ruthenium and rhodium have been significantly extended by the present invention.

In a preferred embodiment, the metal shell of the magnetic rotor consists only of at least one metal of the group of elements consisting of tantalum, niobium, zirconium, titanium, hafnium, gold, platinum, palladium, osmium, iridium, ruthenium and rhodium. In one for the practice Particularly preferred embodiment, the metal shell consists essentially only of tantalum.

Particularly preferred fluorinated hydrocarbons for external encapsulation are fluorinated ethylene-propylene (FEP), ethyltetrafluoroethylene (ETFE), polytetrafluoroethylene (PTFE), perfluoroalkoxyalkane (PFA), ethylene chlorotrifluoroethylene (ECTFE), polyvinylidene fluoride (PVDF) or a combination of different fluorinated hydrocarbons. In this case, the encapsulation of a rotor according to the invention preferably consists only of at least one of the substances polytetrafluoroethylene, perfluoroalkoxyalkane, ethylene, chlorotrifluoroethylene, or polyvinylidene fluoride.

In practice, the permanent magnet of the magnetic rotor is usually positively and / or non-positively connected to the metal shell, so that the permanent magnet in the operating state with respect to the rest of the rotor body can not move substantially. This is crucial for safe driving of the rotor, since the external magnetic drive forces naturally act on the permanent magnet of the rotor, causing the rotor to rotate for pumping the fluid. Likewise, particularly preferably, the metal shell is positively and / or non-positively connected to the encapsulation, in particular to the plastic jacket.

Between the permanent magnet and the metal shell, a recess is particularly advantageously provided, so that the metal shell is weldable without affecting the permanent magnet, which will be explained in more detail below with reference to the drawing.

Finally, in practice, as already mentioned above, to compensate for different thermal expansion of the metal shell and / or If necessary, provided a thermal compensation means of the permanent magnet, so that, for example, at high temperatures no undesirable mechanical stresses between the metal shell and the permanent magnet are induced. Very often, the thermal compensation means is simply a suitably narrow selected gap between the permanent magnet and metal shell, so that a positive and / or frictional connection between the metal shell and the permanent magnet despite the gap is still sufficiently ensured.

The invention further relates to a rotary pump, comprising a pump housing having an inlet for supplying a fluid into the pump housing and an outlet for discharging the fluid from the pump housing, wherein for conveying the fluid in the pump housing, a magnetic rotor is magnetically mounted without contact within a stator and the Rotor is operatively connected to a drive. The rotor is encapsulated by means of an outer encapsulation comprising a fluorinated hydrocarbon. According to the invention, the rotor comprises within the encapsulation a permanent magnet encased in a metal jacket, wherein the metal cladding comprises at least one metal of the group consisting of tantalum, niobium, zirconium, titanium, hafnium, gold, platinum, palladium, osmium, iridium, ruthenium and rhodium ,

To protect the stator itself against the aggressive fluid to be pumped, an inner surface of a housing wall of the pump housing may be provided with a plastic barrier of the fluorinated hydrocarbon, wherein between the inner surface of the housing wall and the stator preferably provided a metal barrier, for example in the form of a pot or cylinder is, which includes at least one metal of the group of elements consisting of tantalum, niobium, zirconium, titanium, hafnium, gold, platinum, palladium, osmium, iridium, ruthenium and rhodium, so that the stator in completely analogous function as the permanent magnet in Inside of the rotor is protected against aggressive fluids to be pumped, especially against the above-mentioned acid mixtures with gaseous components optimally.

The metal jacket of the rotor and / or the metal barrier towards the stator, in particular of the pump housing, consists in a specific embodiment only of at least one metal of the group of elements consisting of tantalum, niobium, zirconium, titanium, hafnium, gold, platinum, palladium, osmium , Iridium, ruthenium and rhodium.

The fluorinated hydrocarbon particularly advantageously comprises fluorinated ethylene propylene (FEP), ethyltetrafluoroethylene (ETFE), polytetrafluoroethylene (PTFE), perfluoroalkoxyalkane (PFA), ethylene chlorotrifluoroethylene (ECTFE), or polyvinylidene fluoride (PVDF), or the encapsulation and / or the plastic barrier at the inner surface of the metal barrier to the stator consists essentially only of at least one of polytetrafluoroethylene, perfluoroalkoxyalkane, ethylene chlorotrifluoroethylene, or polyvinylidene fluoride.

It goes without saying that, of course, the rotor of the rotary pump according to the invention is designed as already described above, and therefore a repeated detailed description of the rotor of the rotary pump according to the invention is unnecessary at this point.

As a drive for the rotary pump of the present invention is advantageously a per se long known bearingless motor, in principle in any embodiment in question, wherein in a particularly preferred embodiment, the stator is configured simultaneously as a bearing and drive stator, and an axial height of the rotor preferred is less than or equal to half the diameter of the rotor, so the rotor is a known so-called pancake.

Fig. 1

ein Ausführungsbeispiel eines erfindungsgemässen Rotors;

Fig. 2

eine erfindungsgemässe Rotationspumpe.

In the following the invention will be explained in more detail with reference to the drawing. In a schematic representation:

Fig. 1

an embodiment of a rotor according to the invention;

Fig. 2

a rotary pump according to the invention.

The Fig. 1 shows in schematic representation in section a magnetic rotor 1 according to the present invention.

The magnetic rotor 1 according Fig. 1 for a rotary pump 2, as in a specific embodiment based on the Fig. 2 will be discussed below, is for conveying a fluid 3 in a pump housing 4 within a stator 5 of the rotary pump 2 in a conventional manner magnetically non-contact and drivable storable. The rotor 1 is encapsulated by means of an outer encapsulation 6 comprising a fluorinated hydrocarbon, wherein the fluorinated hydrocarbon of the encapsulation 6 comprises, for example, polytetrafluoroethylene, perfluoroalkoxyalkane, ethylene, chlorotrifluoroethylene, or polyvinylidene fluoride. In the specific example of Fig. 1 the encapsulation 6 consists only of at least one of the aforementioned fluorinated hydrocarbons. According to the invention, the rotor 1 comprises within the encapsulation 6 a permanent magnet 8 sheathed by the metal sheath 7, the metal sheath 7 comprising at least one metal of the group consisting of tantalum, niobium, zirconium, titanium, hafnium, gold, platinum, palladium, osmium, Iridium, ruthenium and rhodium includes. In the present specific embodiment, the metal shell is only tantalum, except impurities.

Again Fig. 1 can be clearly seen, the permanent magnet 8 is positively connected to the metal shell 7, wherein between the permanent magnet 8 and the metal shell 7, a recess 9 is provided in the form of a chamfer on the permanent magnet, so that the metal shell 7 could be welded without affecting the permanent magnet 8 by excessive temperatures in the manufacture of the rotor 1. In order to prevent penetration of gas-like components diffused through the encapsulation toward the permanent magnet 8 in the operating state, the metal jacket 7 preferably forms a gas-tight jacket of the permanent magnet 8, which is often ensured in practice by first placing the permanent magnet 8 inside the metal jacket 7 is and then the metal shell 7 gas-tight welded or soldered.

Also in Fig. 1 clearly visible is a thermal compensation means 10, which is simply a suitable narrow gap between the permanent magnet 8 and metal shell 7 and serves to compensate for different thermal expansion of the metal shell 7 and the permanent magnet 8 here.

The Fig. 2 finally shows schematically a section of a known rotary pump 2, which is equipped with a rotor 1 according to the present invention. The rotary pump 2 comprises a pump housing 4 with an inlet 11 for supplying a fluid 3 into the pump housing 4 and an outlet 12 for discharging the fluid 3 from the pump housing 4. The fluid 3 is for example a chemically aggressive acid with a proportion of a gas , for example, sulfuric acid with ozone. In order to convey the fluid 3, a magnetic rotor 1 according to the invention is mounted without contact magnetically in a known manner in the pump housing 4, wherein the rotor 1 is likewise known to a drive 13, which comprises electrical coils 131 and the stator as essential elements 5, in particular formed by laminated iron, which are in magnetic operative connection with the permanent magnet 8 of the rotor 1. The drive is here in a special embodiment, a so-called known bearingless Motor is, in which the stator 5 is designed simultaneously as a storage and drive stator. In the specific example of Fig. 2 is the rotor 1 to a so-called pancake, wherein preferably an axial height of the rotor 1 is less than or equal to half a diameter of the rotor 1.

It goes without saying that the invention is not restricted to pancake, but is in principle applicable to all rotor types of any magnetically levitated rotary machines.

According to the invention, the rotor 1 is encapsulated by means of an outer encapsulation 6 made of a fluorinated hydrocarbon and within the encapsulation 6 of the sheathed by the metal shell 7 permanent magnet 8 is provided. The metal shell 7 in this case comprises at least one metal of the group of elements consisting of tantalum, niobium, zirconium, titanium, hafnium, gold, platinum, palladium, osmium, iridium, ruthenium and rhodium.

For reasons of clarity, a plastic barrier made of the fluorinated hydrocarbon provided on an inner surface 411 of a housing wall 41 of the pump housing 4 is provided, wherein a metal barrier in the form of a pot 400 is provided between the inner surface 411 of the housing wall 41 and the stator 5. which comprises at least one metal of the group of elements consisting of tantalum, niobium, zirconium, titanium, hafnium, gold, platinum, palladium, osmium, iridium, ruthenium and rhodium.

The permanent magnet 8 is as in Fig. 1 already described in detail positively and / or non-positively connected to the metal shell 7, wherein a thermal compensation means 10 is provided in the form of a narrow gap between metal shell 7 and permanent magnet 8 to compensate for different thermal expansions of the metal shell 7 and the permanent magnet.

It is understood that all embodiments of the invention described above are to be understood as exemplary only or by way of example, and the invention particularly, but not exclusively, includes all suitable combinations of the described embodiments.

Claims (15)

A magnetic rotor for a rotary pump (2), wherein the rotor for supplying a fluid (3) in a pump housing (4) within a stator (5) of the rotary pump (2) is magnetically non-contact drivable and storable, and the rotor by means of an outer encapsulation (6) comprising a fluorinated hydrocarbon is encapsulated, characterized in that the rotor within the encapsulation (6) comprises a permanent magnet (8) surrounded by a metal shell (7), wherein the metal shell (7) consists of at least one metal of the group of elements of tantalum, niobium, zirconium, titanium, hafnium, gold, platinum, palladium, osmium, iridium, ruthenium and rhodium. A magnetic rotor according to claim 1, wherein said metal sheath (7) is composed of at least one metal of the group consisting of tantalum, niobium, zirconium, titanium, hafnium, gold, platinum, palladium, osmium, iridium, ruthenium and rhodium. Magnetic rotor according to one of claims 1 or 2, wherein the fluorinated hydrocarbon of the encapsulation (6) comprises fluorinated ethylene propylene, ethyltetrafluoroethylene, polytetrafluoroethylene, perfluoroalkoxyalkane, ethylene chlorotrifluoroethylene, or polyvinylidene fluoride, or the encapsulation (6) preferably of at least one of polytetrafluoroethylene, perfluoroalkoxyalkane , Ethylene chlorotrifluoroethylene, or polyvinylidene fluoride. Magnetic rotor according to one of the preceding claims, wherein the permanent magnet (8) is positively and / or non-positively connected to the metal shell (7). Magnetic rotor according to one of the preceding claims, wherein the metal jacket (7) is positively and / or non-positively connected to the encapsulation (6). Magnetic rotor according to one of the preceding claims, wherein between the permanent magnet (8) and the metal shell (7) has a recess (9) is provided, so that the metal shell (7) without deterioration of the permanent magnet (8) is weldable. Magnetic rotor according to one of the preceding claims, wherein a thermal compensation means (10) is provided to compensate for different thermal expansions of the metal shell (7) and / or the permanent magnet (8). A rotary pump comprising a pump housing (4) having an inlet (11) for supplying a fluid (3) into the pump housing (4) and an outlet (12) for discharging the fluid (3) from the pump housing (4), for delivery of the fluid (3) in the pump housing (4) a magnetic rotor (1) within a stator (5) is magnetically non - contact and the rotor (1) with a drive (13) is in operative connection, wherein the rotor (1) by means of a outer encapsulation (6) comprising a fluorinated hydrocarbon is encapsulated, characterized in that the rotor (1) within the encapsulation (6) of a metal shell (7) encased permanent magnet (8), wherein the metal shell (7) at least one metal the group of elements consisting of tantalum, niobium, zirconium, titanium, hafnium, gold, platinum, palladium, osmium, iridium, ruthenium and rhodium. A rotary pump according to claim 8, wherein an inner surface (411) of a housing wall (41) of the pump housing (4) is provided with a housing Plastic barrier is provided from the fluorinated hydrocarbon, and between the inner surface (411) of the housing wall (41) and the stator (5) is preferably provided a metal barrier, which is at least one metal of the group of elements consisting of tantalum, niobium, zirconium, titanium , Hafnium, gold, platinum, palladium, osmium, iridium, ruthenium and rhodium. Rotary pump according to claim 8 or 9, wherein the metal shell (7) of the rotor (1) and / or the metal barrier of at least one metal of the group of elements consisting of tantalum, niobium, zirconium, titanium, hafnium, gold, platinum, palladium, osmium , Iridium, ruthenium and rhodium. A rotary pump according to any one of claims 8 to 10, wherein the fluorinated hydrocarbon comprises fluorinated ethylene-propylene, ethyltetrafluoroethylene, polytetrafluoroethylene, perfluoroalkoxyalkane, ethylene chlorotrifluoroethylene, or polyvinylidene fluoride, or the encapsulant (6) and / or the plastic barrier on the inner surface (411) preferably at least one of the substances polytetrafluoroethylene, perfluoroalkoxyalkane, ethylene, chlorotrifluoroethylene, or polyvinylidene fluoride. Rotary pump according to one of claims 8 to 11, wherein the permanent magnet (8) is positively and / or non-positively connected to the metal shell (7) and / or wherein the metal shell (7) is positively and / or non-positively connected to the encapsulation (6) , Rotary pump according to one of claims 8 to 12, wherein between the permanent magnet (8) and the metal shell (7) has a recess (9) is provided, so that the metal shell (7) without affecting the permanent magnet (8) is weldable. Rotary pump according to one of claims 8 to 13, wherein a thermal compensation means (10) is provided to compensate for different thermal expansions of the metal shell (7) and / or the permanent magnet (8). Rotary pump according to one of claims 8 to 14, wherein the drive is a bearingless motor, and the stator (5) is preferably designed as a bearing and drive stator, wherein preferably an axial height of the rotor (1) is less than or equal to half the diameter of the rotor (1).

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