JP2023050117A - Method for manufacturing pump and slide layer - Google Patents

Abstract

The invention comprises a slide layer (152), the slide layer (152) being an oxide layer, in particular formed by anodization in an electrolyte containing an acid, and a polymer base, in particular based on a fluorine-containing polymer. A pump, particularly a vacuum pump, which overcomes the drawbacks or is at least improved with respect to known means.
The oxide layer is at least partially covered by the sealing and/or the oxide layer is impregnated with the sealing.
[Selection drawing] Fig. 16

Description

The invention relates to a pump, in particular a vacuum pump, comprising at least two pumping elements, for example movable relative to each other, and at least one seal arranged on one of the two pumping elements. According to the invention, a slide layer is provided which is applied at least partially, in particular to at least one of the pumping elements. The invention furthermore relates to the use of a part provided with a sliding layer and at least one seal for producing a pump, in particular a vacuum pump, and a method for producing the sliding layer.

Fluids such as greases or oils can generally be used to seal the pumping space of pumps, in particular vacuum pumps. A piston pump, for example, basically has a gap between the pumping space and the piston. In fluid-sealed or fluid-lubricated configurations, this gap is filled with a fluid, usually oil or grease, during operation of the pump, where the fluid acts as a seal between the piston and the pumping space. . Furthermore, imperfections in the surface structure (cracks, holes, pores, etc.) can act like gaps. In particular, some coatings (paints, anodized aluminum layers, etc.) have defects. A drawback of this type of pump is that the medium pumped by the pump, such as a gas or steam, can react with the fluid used as a seal, which in particular can reduce the effectiveness of the seal. Another problem, particularly in the case of vacuum pumps, consists in contamination of the vacuum vessel by the fluids used.

For this reason, especially for vacuum pumps, so-called dry means, in which the medium to be pumped does not come into contact with the fluid, are preferred. In this case, slide or contact seals are basically used, which are made of chemically resistant materials, usually plastics. For example, in piston pumps, seals of this kind are usually arranged on the piston. During operation, the seal rubs against the inner wall of the cylinder so that the resulting pumping space is sealed as tightly as possible. Other examples of pumps which are normally also dry, i.e., run without fluid lubricant, are scroll pumps or spiral pumps. The scroll pump has a crescent-shaped suction chamber which is formed in cross section by a spiral rotor in engagement with a like spiral stator, the rotor being an eccentric drive. orbited by In order to seal the pumping space, a seal is provided on each scroll end face, the seal on the end face side of the rotor rubbing against the stator and vice versa.

A disadvantage of sliding or contact seals of this kind is that the seals are usually subject to very high wear due to the constantly occurring sliding friction and often have a limited service life. In particular in the suction chamber, wear of the seals in the form of dust can occur after a certain operating time. With increased wear, the sealing effectiveness of contact seals decreases, which leads to poor final pressures achievable.

In order to reduce wear, a sliding or protective layer may be provided, for example as described in EP-A-3153706. A slide layer of this kind may have an oxide layer formed by anodization in an acid-containing electrolyte, in particular oxalic acid, sulfuric acid or mixtures thereof. These sliding/protective layers further improve the corrosion and wear resistance of the substrate. Between the crescent-shaped suction chambers there is a very narrow gap (a few hundredths of a mm). Upon contact between the two parts forming the suction chamber or when solids enter, the hard sliding and protective layers provide an extended service life of the substrate. However, it has been found that oxide layers of this kind, due to their porous structure, cannot achieve the required final pressure and tightness, or can only achieve them after a longer operating time (so-called running-in time). there is Tests have shown that shortening the break-in time or improving the final pressure can be achieved by the process of heating the coated part, especially for freshly coated parts, but the achievable final pressure and break-in time There is still a need for improvement with respect to the reduction of .

EP-A-3153706

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a pump which overcomes the aforementioned drawbacks or is at least improved with respect to the known measures.

This problem is solved by a pump and a method according to the independent claims.

A pump according to the invention is preferably a vacuum pump. The pump comprises a slide layer, the slide layer having an oxide layer and a seal formed from a fluorine-containing polymer, the oxide layer at least partially covered by the seal, and /or the oxide layer is impregnated with a seal.

As referred to herein, the sliding layer can meet multiple properties. Particularly when used in scroll pumps, such as scroll vacuum pumps, the sliding layer serves two functions: 1) the sliding layer, ie optimization of the tribological system, and 2) a protective layer, ie protecting the substrate from damage, wear and corrosion. protection and fulfillment. Tests have shown that without a hard surface coating on a scroll pump, substrate damage can occur within a very short time.

The oxide layer is preferably formed by anodization, especially in an acid-containing electrolyte. Preferably, the electrolyte comprises oxalic acid and/or sulfuric acid, with sulfuric acid being even more preferred. The oxide layer is preferably alumite formed by electrolytic oxidation of aluminum. The oxide layer can have the aforementioned multifunctional properties with respect to sliding and protective effects.

A pump according to the invention comprising a slide layer with an oxide layer, for example in the form of a polyurethane layer or a polyurethane impregnation, and a seal, may be provided with a slide layer as described, for example, in EP-A-3153706. has been found to allow a lower final pressure than Hard oxide layers deposited to protect against wear have pores, defects and thermally induced cracks. The pores are arranged mainly perpendicular to the layer, in which case there are also some branches within the layer connecting the vertical pores arranged horizontally to the layer. In addition to pores, a hard oxide layer of this kind has other defects and cracks, for example in the form of inclusions. Defects and pores form microscopic passages through which gas can flow. In addition, outgassing of substances such as water can occur from these points. This reduces the tightness, which adversely affects the achievable final pressure. This means that the required final pressure and tightness are not achievable or are only achievable after longer operating times. During the so-called running-in process, the pores or defect sites are mainly closed by wear of the seals at the relevant points. Furthermore, outgassing of mixed media, eg coating residues, can occur. It has been found that the seal allows the required final pressure to be reached very quickly while at the same time maintaining a high protection against wear. This is probably due to the fact that in the pump according to the invention the pores contained in the oxide layer are closed by a seal to prevent gas flow in or out of the slide layer. Or at least it can be explained by being reduced.

Preferably, the pump, in particular the vacuum pump, further comprises at least two pumping elements movable with respect to each other and further comprises at least one seal arranged on one of both pumping elements, these pumping elements interact sealingly while forming at least one pumping space. In this case, the sliding layer is at least partially applied to at least one of the pumping elements and interacts with the respective seal.

According to another preferred aspect of the invention, the pump is a spiral or scroll pump, in particular a spiral or scroll vacuum pump, wherein the slide layer is at least partially covered by at least one of the pumping elements. is worn.

A spiral or scroll pump, in particular a spiral or scroll vacuum pump, is preferably a pump in which the pumping elements are two scroll elements movable relative to each other, the scroll elements each on a support: It has walls spirally extending about an axis with free end faces and the walls are arranged to sealingly engage one another in and out while forming a pumping space, wherein the seal is , which is located on the free end face of the wall, is a pump.

According to yet another aspect of the invention, the pump is a piston pump, in particular a piston vacuum pump, comprising at least one cylinder having an inner wall of the cylinder and a piston movable within the cylinder. In this case the pumping element is a cylinder and a piston movable within the cylinder, in which case the seal is arranged on the piston and/or on the inner wall of the cylinder. In this configuration, the slide layer is at least partially applied on the inner wall of the cylinder and/or on the piston.

Preferably, in the pump according to the invention, the fluorine-containing polymer contained in the seal is a fully fluorinated polymer, i.e. a perfluoropolymer, or a polymer with perfluoro segments. Closures comprising fluorine-containing polyurethanes, in particular polyurethanes with perfluoro segments, have proven particularly suitable. It has been found that polyurethanes of this kind with perfluoro segments allow low final pressures at the same time as short running-in times, while at the same time maintaining high wear resistance. It is likewise preferred according to the invention for the seal to be made of polyurethane with polyether segments. Polyurethanes with polyether segments have also proven particularly suitable with regard to low final pressure, short running-in times and high wear resistance. Even more preferably, therefore, the polyurethane layer is formed from a polyurethane having perfluoropolyether segments. The perfluoropolyether segments provide particularly low end pressures and short break-in times while at the same time providing very good wear resistance. Perfluoropolyether segments may be provided in the dispersion as a polyol prepolymer or as a diisocyanate prepolymer to create the seal. Perfluoropolyether segments may be, for example, segments based on perfluoropolyethylene glycol or perfluoropolypropylene glycol, preferably perfluoropolyethylene glycol. The slide layer of the pump according to the invention preferably comprises at least one fluorinated polymer different from PTFE. PTFE is not ideal for sealing porous oxide layers due to its particle size and its associated relatively high gas permeability. Thus, PTFE may be included, but in this case at least one other polymer different from PTFE should be included.

In the sliding layer of the pump according to the invention, the sealing, for example in the form of a polyurethane layer, is obtained by applying a dispersion, for example a polyurethane dispersion, to the oxide layer. The seal may be applied in the form of an aqueous dispersion or may be applied in the form of a solvent-based dispersion. When solvent-based dispersions, the solvent is preferably a C ₁ -C ₈ alcohol, especially a C ₃ -C ₆ alcohol, such as a C ₄ alcohol. Preferably, the seal is obtained by application of an aqueous polyurethane dispersion, in particular an aqueous ionic polyurethane dispersion, preferably an anionic polyurethane dispersion. Dispersions of anionic polyurethanes based on perfluoropolyether (PFPE) backbones have proven to be particularly advantageous. For example, suitable anionic polyurethane dispersions are available from Solvay under the trade name Fluorolink.

Application of the dispersion can be performed using spraying, dipping, blade coating or spin coating. Application by spraying or dipping has proven to be advantageous with respect to ease of implementation, where spraying is particularly advantageous with respect to uniformity and particularly thin layer formation. Application by blade coating or spin coating can likewise produce very uniformly thin coatings. According to a preferred embodiment, the dispersion is selectively applied to surfaces with a particularly sealing action.

According to the invention, the thickness of the sealing, for example in the form of a polyurethane layer, is not limited to a particular thickness. However, seals with a thickness of 0.1 μm to 35 μm have proven advantageous with respect to the balance between low final pressure and short running-in time on the one hand and high wear resistance on the other hand. Preferably, the thickness of the encapsulant is 0.5 μm to 25 μm, more preferably 0.8 μm to 20 μm, even more preferably 1.0 μm to 15 μm, very preferably 1.5 μm to 10 μm. Most preferably, the layer thickness of the sealing portion is 5 μm or less. The seal can be impregnated into the pores of the oxide layer without a discernible continuous layer of fluorine-containing polymer covering the oxide layer. By impregnation, defects connecting the pores of the oxide layer can be filled, thus improving airtightness. In the pump according to the invention, the sealing, for example in the form of a polyurethane layer, preferably covers the oxide layer substantially completely or completely. By complete or substantially complete coverage, the pores contained in the oxide layer are closed, thus preventing bypass of the pumped medium through the slide layer. Thus, particularly low final pressures can be achieved with short running-in times.

To improve wear resistance, the pump according to the invention preferably contains an adhesion promoter in the slide layer. Adhesion promoters are generally reactive compounds which improve the adhesion of the seal, preferably in the form of a polyurethane layer, to the oxide layer. Adhesion promoters of this type are known to the person skilled in the art. For example, it may be an epoxy compound, a siloxane compound, an aziridine-derived compound, a melamine compound or a blocked isocyanate compound. Epoxysilanes and polyaziridines have proven to be particularly suitable adhesion promoters. Adhesion promoters of this kind may be included in the polyurethane layer and/or the sealing portion constructed as a polyurethane impregnate, for example by adding it to the polyurethane dispersion used to form the polyurethane layer. Alternatively or additionally, it is also possible to apply an adhesion promoter to the oxide layer before applying the seal. In this case the adhesion promoter acts as a primer on the oxide layer.

Preferably, the pump according to the invention has a pumping element consisting of a base material at least partially made of aluminum or an aluminum alloy, on which the slide layer is applied. Preferably, the pumping element consists of aluminum or an aluminum alloy. Particularly preferably, the base material is an aluminum alloy of the AlMgSi series. Aluminum alloys based on AlMgSiMn, AlMgSiPb or AlZnMg are furthermore advantageous. Aluminum and aluminum alloys have been found to be particularly suitable for anodizing in electrolytes containing acids and for forming sliding layers according to the present invention. In this case, the electrolyte preferably contains oxalic acid, sulfuric acid or mixtures thereof. More preferably, the electrolyte contains sulfuric acid.

Furthermore, the present invention provides a method for manufacturing a slide layer, comprising the following steps a) forming an oxide layer, in particular by anodization in an electrolyte, preferably containing an acid;
b) coating the oxide layer with the seal;
A method comprising:

Of course, an oxide layer is formed in step a) on the substrate, for example on the pumping element of the pump, as described above.

Preferably, in step b) the pores and defects contained in the oxide layer are closed by sealing. This results in a sliding layer in which the lateral connections and defects between the pores of the oxide layer are blocked, thereby improving the tightness. The seals used in the method according to the invention are in particular seals as described above in connection with the pump according to the invention.

The method according to the invention is preferably part of the manufacture of pumps, in particular vacuum pumps, as described herein.

Of course, the individual aspects of the invention, in particular the aspects described below with reference to the drawings, can also be advantageously combined with each other.

The invention is explained below, purely by way of example, on the basis of schematic drawings and examples.

1 shows a scroll pump in cross section. 3 shows the electronics housing of the scroll pump. FIG. 1 shows a scroll pump in perspective view, with selected elements exposed. Figure 3 shows a pressure sensor built into the pump; Figure 3 shows the movable scroll member of the pump; FIG. 5 shows another side of the scroll member, opposite the side visible in FIG. Fig. 3 shows a clamping device for a scroll member; Figure 3 shows an eccentric shaft with different scroll pump balance weights. Figure 3 shows an eccentric shaft with different scroll pump balance weights; 1 shows a gas ballast valve with an operating grip in a perspective view; FIG. Figure 11 shows the valve of Figure 10 in cross-section; Figure 7 shows a partial area of the scroll member of Figures 5 and 6; Fig. 10 shows a cross-sectional view of the scroll member through the scroll wall at the outer end region; 2 shows an air guide hood of the scroll pump of FIG. 1 in a perspective view; FIG. FIG. 4 shows a breakaway screw thread in cross section; FIG. 2 is a detailed view of the spiral or scroll pump according to FIG. 1; FIG. Fig. 2 shows a cross-sectional view of an oxide layer through an electromicroscope; 17 shows a greatly enlarged cross-sectional view through an electron microscope of the oxide layer of FIG. 16; FIG. Figure 18 shows an electron microscopic plan view of the oxide layer of Figures 16 and 17; Figure 2 shows the generation of vacuum when using a scroll pump with variously coated and uncoated pumping elements.

Even if the invention is not limited to scroll pumps 20, it has been found to be very suitable therefor. In principle, the pump according to the invention may also be a piston pump (not shown). For the generally mentioned component seals (eg static seals in oxide layers, eg O-ring seals), seals are also suitable, as described herein. FIG. 1 shows a vacuum pump configured as scroll pump 20 . The vacuum pump comprises a first housing element 22 and a second housing element 24, wherein the second housing element 24 comprises a pumping structure or scroll wall 26. As shown in FIG. The second housing element 24 thus forms a stationary scroll member of the scroll pump 20 . Scroll wall 26 interacts with scroll wall 28 of movable scroll member 30, where movable scroll member 30 is eccentrically excited via eccentric shaft 32 to produce a pumping action. In this case, the gas to be pumped is pumped from an inlet 31 set in the first housing element 22 to an outlet 33 set in the second housing element 24 .

Eccentric shaft 32 is driven by motor 34 and journaled by two rolling bearings 36 . The eccentric shaft 32 has an eccentric journal 38 which is arranged eccentrically with respect to the axis of rotation of the eccentric shaft 32 , the eccentric journal 38 being eccentrically rocked via a further rolling bearing 40 . is transmitted to the movable scroll member 30 . For sealing purposes, the movable scroll member 30 is also fitted with a corrugated bellows 42 at its left-hand end in FIG. there is The left end of the corrugated bellows 42 follows the rocking motion of the movable scroll member 30 .

The scroll pump 20 has a fan 44 for generating cooling airflow. An air guide hood 46 is provided for this cooling air flow. A fan 44 is also attached to the air guide hood 46 . The air guide hood 46 and the housing elements 22, 24 are shaped such that the cooling airflow is generally passed around the entire pump housing, thus achieving good cooling performance.

The scroll pump 20 further includes an electronics housing 48 in which the controller and power electronics components for driving the motor 34 are located. Electronics housing 48 also forms the stand legs of pump 20 . A passageway 50 is visible between the electronics housing 48 and the first housing element 22 . Through passage 50, airflow generated by fan 44 is guided along first housing element 22 and also along electronics housing 48, so that both are effectively cooled.

Electronics housing 48 is shown in particular detail in FIG. Electronics housing 48 has a plurality of individual chambers 52 . In these chambers 52 electronic components can be enclosed and are therefore advantageously shielded. Advantageously, when encapsulating electronic components, as little encapsulant material as possible can be used. For example, the encapsulant material may first be introduced into chamber 52, followed by pushing the electronic components. Preferably, the chamber 52 may be configured to allow various forms of electronic components, particularly substrates of various implementations, to be placed and/or enclosed within the electronics housing 48 . In this case, in certain forms, individual chambers 52 may remain empty, ie, without electronic components. A so-called modular system can thus be easily realized for different pump types. The encapsulating material may be designed in particular to be thermally conductive and/or electrically insulating.

A plurality of walls or fins 54 are formed on the rear side of the electronics housing 48 with respect to FIG. 2 and define a plurality of passages 50 for directing cooling airflow. Chamber 52 also allows particularly good heat dissipation from electronic components arranged in chamber 52 to fins 54 in conjunction with a particularly thermally conductive encapsulating material. The electronic component can thus be cooled particularly effectively and its service life is improved.

3 shows the entire scroll pump 20 in a perspective view, in which the air guide hood 46 is omitted so that the fixed scroll member 24 and the fan 44 are particularly visible. The stationary scroll member 24 is provided with a plurality of radially disposed recesses 56 each defining a fin 58 disposed between the recesses 56 . The cooling airflow generated by the fan 44 is guided through the recesses 56 and by the fins 58, thus cooling the stationary scroll member 24 particularly effectively. In doing so, the cooling air flow first flows around the stationary scroll member 24 and only then around the first housing element 22 or the electronics housing 48 . This arrangement is particularly advantageous since the pumping area of the pump 20 has a high heat release due to compression during operation and is therefore preferentially cooled there.

The pump 20 has a pressure sensor 60 built into the pump 20 . This pressure sensor 60 is located within the air guide hood 46 and is screwed onto the stationary scroll member 24 . The pressure sensor 60 is connected to the electronics housing 48 and the control device arranged therein via a cable connection which is only partially shown. In this case, the pressure sensor 60 is incorporated in the control section of the scroll pump 20 . For example, motor 34 , visible in FIG. 1, can be controlled in response to pressure measured by pressure sensor 60 . For example, if pump 20 is used in a vacuum system as a backing pump for a high vacuum pump, for example, high vacuum pump can only be switched on when pressure sensor 60 measures a sufficiently low pressure. The high vacuum pump can thus be protected from damage.

FIG. 4 illustrates in cross-section the pressure sensor 60 and the placement of the pressure sensor 60 on the stationary scroll member 24 . A passageway 62 is provided for the pressure sensor 60, the passageway 62 here being the non-pumping outer region between the scroll wall 26 of the stationary scroll member 24 and the scroll wall 28 of the movable scroll member 30. open to The pressure sensor thus measures the suction pressure of the pump. Alternatively or additionally, the pressure between, for example, scroll wall 26 and scroll wall 28 may be measured in the pumping region. Thus, depending on the position of pressure sensor 60 or channel 62, for example, intermediate pressures can also be measured.

The pressure sensor 60 makes it possible in particular to recognize the wear state of the pumping components, in particular the sealing elements 64, also called tip seals, for example via the determination of the compression. Furthermore, the measured suction pressure may be used to control the pump (especially the pump speed). Thus, for example, the suction pressure can be preset on the software side and adjusted by changing the pump speed. Depending on the measured pressure, it is also conceivable that the pressure increase caused by wear can be compensated for by increasing the rotational speed. Therefore, it is possible to defer tip seal replacement or implement longer replacement intervals. In short, the pressure sensor 60 data can generally be used for, for example, wear determination, conditional control of pumps, process control, and the like.

A pressure sensor 60 may optionally be provided, for example. Instead of the pressure sensor 60, for example a blind plug closing the passageway 62 may be provided. In this case, the pressure sensor 60 can be retrofitted, for example, if desired. Particularly for retrofitting, and generally advantageous, it can be envisaged that the pressure sensor 60 is automatically recognized when it is connected to the control device of the pump 20 .

Pressure sensor 60 is positioned in the cooling airflow of fan 44 . This also advantageously cools the pressure sensor 60 . Furthermore, as a result, no special measures need to be taken to increase the heat resistance of the pressure sensor 60, so a low cost sensor can be used.

Furthermore, the pressure sensor 60 is arranged in particular such that the outer dimensions of the pump 20 are not enlarged by the pressure sensor 60 and thus the pump 20 is kept compact.

5 and 6 show the movable scroll member 30 in various viewing directions. In FIG. 5 the spiral structure of the scroll wall 28 is particularly well visible. In addition to scroll wall 28, scroll member 30 has a base plate 66 from which scroll wall 28 extends.

The side of base plate 66 opposite scroll wall 28 is visible in FIG. On this side, the base plate has, inter alia, a plurality of mounting cavities for mounting bearings 40 and corrugated bellows 42 visible in FIG. 1, for example.

The outside of the base plate 66 is provided with three retaining projections 68 spaced around the circumference of the base plate 66 and evenly distributed around the circumference. In this case, the retaining projections 68 extend radially outward. The retaining projections 68 in particular all have the same radial height.

Between the two retaining projections 68 extends a first intermediate portion 70 of the circumference of the base plate 66 . The first intermediate portion 70 has a greater radial height than the second intermediate portion 72 and the third intermediate portion 74 . The first intermediate portion 70 is positioned opposite the outermost 120° portion of the scroll wall 28 .

In fabricating movable scroll member 30, base plate 66 and scroll wall 28 are preferably machined together from a single solid piece of material, i.e., scroll wall 28 and base plate 66 are integrally formed. ing.

For example, the scroll member 30 may be directly clamped with the retaining projections 68 during finishing. Within the same single clamping, for example, the side of the base plate 66 shown in FIG. 6 can also be machined, in particular the mounting cavities. Fundamentally, within the scope of this clamp, the manufacture by cutting of the scroll wall 28 from solid material is also possible.

For this purpose, the scroll member 30 may be clamped, for example using a clamping device 76, as shown in FIG. The clamping device 76 has a hydraulic three-jaw chuck 78 that directly abuts the three retaining projections 68 . Additionally, the clamping device 76 has a cavity 80 therethrough which allows tool access to the scroll member 30, particularly to the side of the scroll member 30 shown in FIG. Thus, multiple machining operations can be performed from both sides during clamping, in particular the finishing of at least one of the scroll walls 28 and the machining of the mounting cavities.

The contour of retaining projection 68 and the clamping pressure of clamping device 76 are preferably selected such that critical deformation of scroll member 30 does not occur. The three retaining projections 68 are preferably selected such that the outer dimensions, ie the maximum diameter of the scroll member 30, are not enlarged. Thus, on the one hand, material and on the other hand, the amount of machining can be saved. The retaining projections 68 are specifically configured and/or arranged in such an angular position that access to the threaded connection of the corrugated bellows 42 is provided. The number of threaded fastening points on corrugated bellows 42 is preferably not equal to the number of retaining projections 68 on movable scroll member 30 .

Mounted on the eccentric shaft 32 of FIG. 1 are two balance weights 82 for compensating for imbalances in the excited system. FIG. 8 shows an enlarged view of the area of the balance weight 82 on the right side in FIG. The balance weight 82 is screwed onto the eccentric shaft 32 .

FIG. 9 shows a similar partial view of another scroll pump, preferably belonging to the same series as the pump 20 of FIG. The pump according to FIG. 9 in particular has different dimensions and therefore requires another balance weight 82 .

The eccentric shaft 32, the balance weight 82 and the housing element 22 are each in the mounting position shown, only one particular type of the two types of balance weights 82 shown can be assembled to the eccentric shaft 32. Dimensioned as such.

The balance weight 82 is sized in FIGS. 8 and 9 with specific dimensions of the structural space set for the balance weight 82 so that the balance weight 82 in FIG. It is clear that it is not possible and vice versa. Of course, the dimensions given are given only by way of example.

Thus, in FIG. 8, the distance between mounting hole 84 and shaft shoulder 86 is 9.7 mm. The balance weight 82 in FIG. 8 is shorter in the corresponding direction, i.e. 9 mm long, and can therefore be installed without problems. The balance weights 82 of FIG. 9 each have an extended length of 11 mm measured from the mounting hole. Therefore, the balance weight 82 of FIG. 9 cannot be attached to the eccentric shaft 32 of FIG. 8 either because the shaft step 86 collides with the balance weight 82 when attempting to assemble, or because the balance weight 82 of FIG. 9 cannot fully abut the eccentric shaft 82 of FIG. be. The balance weight 82 of FIG. 9 is also prevented from being assembled backwards by having both dimensioned dimensions greater than the distance between the mounting hole 84 and the shaft shoulder 86 of FIG. In addition, the 21.3 mm dimension of the balance weight 82 in FIG. 8 prevents reverse and therefore incorrect assembly orientation of the normally correct balance weight 82 .

In FIG. 9, the longitudinal distance between mounting hole 84 and housing shoulder 88 is 17.5 mm. The balance weight 82 of FIG. 8, which has an extension of 21.3 mm, would collide with the housing shoulder 88 when trying to insert it into the eccentric shaft 32 of FIG. 9, so complete assembly is not possible. be. Incorrect impositions, although possible for the time being, are definitely recognized. When the balance weight 82 shown in FIG. 8 is rotated about the axis of the mounting hole 84 and assembled to the eccentric shaft 32 shown in FIG. It would collide with the spaced apart shaft shoulder 86 .

The balance weights 82, in particular the motor-side balance weights 82, are generally configured in such a way that, during assembly and/or maintenance, mix-ups between balance weights and balance weights with other structural sizes are avoided. The balance weights are preferably attached using through screws. Similar balance weights of various pump sizes may be incorrect due to, among other things, the adjacent shoulders on the shaft, the location of the threads and through holes of the balance weights, and the location of the shoulders within the housing. is configured to prevent the assembly of

10 and 11 show the gas ballast valve 90 of the scroll pump 20. FIG. Gas ballast valve 90 is also visible in the overall view of pump 20 in FIG. 3 and is located on stationary scroll member 24 .

Gas ballast valve 90 has an operating grip 92 . The operating grip 92 has a plastic body 94 and a base element 96, preferably made of stainless steel. The base element 96 has a hole 98 therethrough, which on the one hand is provided for connecting and introducing ballast gas and on the other hand surrounds the non-return valve 100 . The hole 98 is also closed by a plug 102 in the drawing. Instead of the plug 102, for example, a filter may be provided, in which case the ballast gas may preferably be air and enters the valve 90 via the filter, in particular directly.

Operating grip 92 is attached to pivotable element 106 of valve 90 by three mounting screws 104 . A mounting screw 104 is positioned within each hole 108, only one of which is visible in the selected cross-sectional view of FIG. The rotatable element 106 is rotatably attached to the second housing element 24 by mounting screws extending through holes 110, not shown.

In order to operate the valve 90, a rotational moment manually applied to the operating grip 92 is transmitted to the rotatable element 106, thus causing the rotatable element 106 to rotate. This allows the hole 98 to communicate with the interior of the housing. In this case, the valve 90 is provided with three switching positions, i.e. the switching position shown in FIG. In the closed position and rotated to the left and right, the holes 98 communicate with different regions of the interior of the housing.

Apertures 108 , 110 are closed by lids 112 . The sealing action of the gas ballast valve 90 is by an axially pressed O-ring. When valve 90 is operated, relative movement is exerted on the O-ring. For example, if dirt such as particles reaches the surface of the O-ring, there is a risk of premature failure. The lid 112 prevents dirt and the like from entering the threads of the grip 92 .

This lid 112 is attached via an interference fit of three centering elements. Specifically, the lid 112 has an insert pin (not shown) for each hole 108 by which the lid 112 is retained in the hole 108 . Thus, the holes 108, 110 and the mounting screws located therein are protected from contamination. In particular, a mounting screw, not shown, located in hole 110, which allows pivoting movement, effectively minimizes the ingress of dirt into the valve mechanism, thus improving the service life of the valve.

A plastic grip injection molded around a special steel base part provides good corrosion resistance and at the same time low production costs. Furthermore, due to the reduced thermal conductivity, the plastic of the grip remains relatively cool, which allows for good handling.

The fan 44 is preferably provided with a speed control, as can be seen, for example, in FIGS. 1 and 3 . The fan is controlled by PWM, for example, depending on the power consumption and temperature of the power module housed in the electronics housing 48 . The rotation speed is adjusted according to power consumption. However, control is only possible from a module temperature of 50°C. Once the pump is in the temperature range of possible derating (temperature-induced power drop), it will automatically control to maximum fan speed. This control achieves a minimum noise level at cold pumps, a low noise level (corresponding to the pump noise) at final pressure or low load, and a low noise level and at the same time optimum cooling of the pump. , and maximum cooling power can be ensured before temperature-induced power reduction.

The maximum fan speed may be adaptable depending on the particular situation. For example, lowering the maximum fan speed can be effective for high water vapor compatibility.

In FIG. 12 the movable scroll member 30 is shown partially and enlarged compared to FIG. A cross-sectional view of scroll member 30 taken along line AA shown in FIG. 12 is shown schematically, although not to scale, in FIG.

The scroll wall 28 is provided on the side opposite the base plate 66 and at the base-plate-facing end of the stationary scroll member 24, not shown here, with a sealing element 64, also not shown here, ie the so-called It has a groove 114 for inserting the tip seal. The arrangement in the operating state is well visible in FIG. 4, for example. According to an advantageous embodiment of the pump according to the invention, a tip seal is provided, which is in sliding contact with the slide layer.

The groove 114 is defined on the outside and inside by two opposing sidewalls, an inner sidewall 116 and an outer sidewall 118 . In the first scroll portion 120 , the outer sidewall 118 is thicker than the inner sidewall 116 in the first scroll portion 120 and thicker than both sidewalls 116 , 118 in the separate second scroll portion 122 . is also thickly constructed.

The first scroll portion 120 extends from the point shown in FIG. 12 to the outer end of the scroll wall 28, as also shown in FIG. 5, for example. The first scroll portion 120 here extends, for example, over 163°.

A first scroll portion 120 forms the outer end portion of the scroll wall 28 . In this case, the first scroll portion 120 is arranged at least partially, in particular completely, in the non-pumping region of the scroll wall 28 . In particular, the first scroll portion 120 may occupy at least substantially completely the non-pumping area of the scroll wall 28 .

As can be seen in FIG. 5, the first intermediate portion 70, which preferably has a greater radial height than the other intermediate portions 72, 74, is positioned between the two retaining projections 68 at the first It may be arranged opposite one scroll portion 120 . Therefore, the imbalance introduced by the thicker sidewalls 118 can be compensated for by the greater weight of the first intermediate portion 70 .

In order to keep system loads on bearings and other components low, the movable scroll member should generally preferably have a low dead weight. The scroll wall is therefore usually constructed very thin. Furthermore, the thinner the walls, the smaller the pump dimensions (effective outside diameter). As a result, the sidewalls of the tip seal groove are particularly thin. The ratio of tip seal wall thickness to total scroll wall thickness is, for example, a maximum of 0.17. However, due to the tip seal groove, the scroll wall tip is very sensitive to bumps during handling, such as during assembly or tip seal replacement. Even slight bumps, for example during transport, can press the side walls of the groove inwards, so that the tip seal can no longer be assembled. To solve this problem, the groove has an asymmetrical wall thickness, in particular an outwardly directed local thickening of the scroll wall. This region is preferably non-pumping and may therefore be manufactured with greater tolerances. Damage is greatly reduced by the one-sided thickening, especially in the last half turn. The remainder of the component preferably does not require thickening of the scroll wall. This is because the wall is protected by the protruding elements of the component.

The air guide hood 46 shown in FIG. 1 defines airflow as suggested by dashed arrows 124 . The fan 44 is connected via a cable (not shown) extending through the air guide hood 46 and a plug-in connection to a control device provided in the electrohousing 48 . The bayonet connection has a socket 126 and a plug 128 . Socket 126 is attached to a substrate that is supported by and/or positioned within electronics housing 48 . Socket 126 is also visible in FIGS. 2 and 3, for example. Plug 128 is connected to fan 44 via a cable not shown.

The bayonet connections 126 , 128 are separated from the air flow 124 by a partition 130 . The airflow 124 may contain dust or similar dirt, for example, and is thus isolated from the bayonet connections 126,128. Thus, on the one hand the plug connections 126, 128 themselves are protected, and on the other hand dirt can enter the electronics housing 48 through the openings in the electronics housing 48 provided for the socket 126, Access to the control unit and/or power electronics is blocked.

FIG. 14 shows the air guide hood 46 separately in a perspective view. In particular, the partition wall 130 is visible with the space provided for the plug 128 set behind the partition wall 130 . Partition wall 130 has a recess 132 , here configured as a V-shaped cut, for conducting cables from plug 128 towards fan 44 .

Low cost plug-in connectors without seals (eg without IP protection cords) can be used, for example to reduce costs. This is because the partition wall 130 prevents the inhaled air from reaching the electronics via the penetrations of the plug-in connectors 126,128. The fan cables are guided laterally through the partition 130 by V-shaped notches 132 . The notch 132 has a lateral offset with respect to the bayonet connectors 126, 128 to achieve a labyrinth effect and thus further reduction of cooling air leakage to the bayonet connectors 126, 128. be. A partition wall 130 in the air guide hood 46 further improves the air guidance into the passageway 50 between the electronics housing 48 and the pump housing 22 . Relatively little fan 44 turbulence and back pressure is produced.

FIG. 15 shows in schematic cross section the abutment area between the first housing element 22 and the second housing element or stationary scroll member 24 . The second housing element 24 is partially inserted into the first housing element 22 with an intermediate fit 134 . In this case, a seal using an O-ring 136 is provided. Intermediate fit 134 also serves, for example, to center second housing element 24 with respect to first housing element 22 .

For maintenance purposes, for example to replace the sealing element 64, the second housing element 24 has to be removed, for example. In doing so, pinching of the intermediate fit 134 or the O-ring 136 can occur when the second housing element 24 is not pulled out straight enough. To solve this problem, breakaway threads 138 are provided. Preferably, at least approximately diametrically opposite second tear-off threads may be provided. In order to guide and remove the second housing element 24 as straight as possible, the screw is pulled off the breakaway thread until the screw projects out of the breakaway thread 138 and abuts the first housing element 22 . 138 can be screwed. Further screwing separates the housing elements 22, 24 from each other.

To pull apart, for example, mounting screws 142 provided for mounting the second housing element 24 to the first housing element 22, as shown in FIGS. 1 and 3, can be used. For this purpose, the breakaway threads 138 preferably have the same thread type as the mounting threads provided for the mounting screws 142 .

The second housing element 22 is provided with recesses 140 associated with the tear-off threads 138 . If the wear particles are entrained when the screw is screwed into the breakaway threads 138 , the wear particles collect in the recesses 140 . Wear particles of this kind are thus prevented, for example, from preventing complete abutment of the housing elements 22, 24 together.

When assembling the stationary scroll member 24, the screws must be unscrewed again. This is because otherwise the complete screwing of the stationary scroll member 24 in the first housing element 22 (correct fit in the plane of the housing) may possibly be prevented. As a result, leaks, tilting and poor pump performance can occur. In order to avoid this assembly error, the air guide hood 46 has, in particular additional, at least one dome 144 shown in FIG. Assembly of the air guide hood 46 is only possible when the screws 142 are removed again. The air guide hood 46 with the dome 144 is configured so that it collides with the screw head of a breakaway screw that is optionally threaded into the breakaway thread 138 so that the air guide hood 46 is completely is not assemblable. In particular, the air guide hood 46 can only be assembled when the tear-off screws have been completely removed.

FIG. 16 schematically shows a detailed view of the spiral or scroll pump 20 shown in the preceding figures, in the region where the seal 150 contacts a support 154 provided with a sliding layer 152 in the form of the base plate 66. show. In particular, the scroll elements 26 , 28 are arranged such that the seal 150 is pressed against a support 154 in the form of the base plate 66 . Compression of the seal against the base plate is accomplished via a pressure differential between opposite sides of the scroll elements 26,28. Seal 150 is joined to scroll elements 26 , 28 via interface 151 . The oxide layer and seals of slide layer 152 are not shown separately as the seals enter and close pores and defects in the oxide layer. The construction of additional layers does not necessarily take place. The seal, which preferably comprises a fluoropolymer, not only promotes the dry lubricating properties of the sliding layer 152 and additionally reduces its wear, but also improves the hermeticity of the sliding layer 152, thereby increasing the achievable Improved final pressure and reduced break-in time result.

The support 154 in the form of the base plate 66 and the spiral walls 26, 28 are each integrally constructed and made of an aluminum alloy of the AlMgSi series. The oxide layer of slide layer 152 is an aluminum oxide layer formed by anodization in a sulfuric acid electrolyte. The slide layer 152 is applied in particular on all sides of the scroll members 24, 30 facing the pumping space. The seal 150 (tip seal) shown in FIG. 6 is, for example, polytetrafluoroethylene containing polyimide particles and made by hot compression molding followed by sintering. The average particle size of polyimide particles is 25 μm.

The seal is preferably a seal applied as an aqueous anionic polyurethane dispersion, in which case the polyurethane comprises perfluoropolyether segments. Perfluoropolyether segments may be provided as polyol prepolymers or diisocyanate prepolymers. Perfluoropolyether segments may be, for example, segments based on perfluoropolyethylene glycol or perfluoropolypropylene glycol, preferably perfluoropolyethylene glycol. An adhesion promoter was added to the polyurethane dispersion to improve the bonding of the seal to the oxide layer. For example, epoxysilanes or polyaziridines have been added. Alternatively or additionally, other adhesion promoters such as melamine or blocked isocyanates may be added. The encapsulant may be acrylate-based or sol-gel-based, in which case, as mentioned above, the use of adhesion promoters is likewise advantageous for acrylate-based or sol-gel-based seals. be.

The pump according to the invention may have one or more of the features described above with reference to FIGS. 1 to 16, where any combination of these features can be realized in the pump according to the invention. .

FIG. 17 shows a cross-sectional electron microscope image showing oxide layer 156 having a thickness of 39.08 μm deposited on base plate 66 . The scale of FIG. 17 indicates a length of 10 μm. The oxide layer 156 has cracks 158 and defects 158 that impair hermeticity. A still further enlarged view is shown in FIG. 18, in which not only the pore structure but also the defects connecting the pores to each other are visible. The scale of FIG. 18 indicates a length of 200 nm. The porous structure of oxide layer 156 can also be seen based on FIG. FIG. 19 shows an electron microscopic plan view of the oxide layer of FIGS. 17 and 18, in which pores 160 appear as dark, vertically extending streaks, and very small defects 158 also appear as adjacent strips. It is visible as a dark pattern connecting the holes 160 to each other. The scale of FIG. 18 indicates a length of 200 nm. Very small pores 160 as well as larger pores 160, cracks 158 and their branches are visible. Only some of the pores and defects are labeled in FIGS. 17-19, respectively.

The effect of the sliding layer of the pump according to the invention can be seen on the basis of the graph shown in FIG. Time is plotted in hours on the horizontal axis (X-axis) and pressure in hPa on the vertical axis. Under the same conditions in each case, a negative pressure was generated using a scroll vacuum pump, and the occurrence of each negative pressure was recorded over time.

A HiScroll type pump was used in each line from A to D. In line A, the pumps differ only in that the pumping element does not have a coating. In line B, the pumping element has a coating as described in EP-A-3153706, in which a sulfuric acid electrolyte was used to create the oxide layer, i.e. anodization It has a polished oxide layer. Line C is the same HiScroll type pump as for line B, but the coating was heated for a period of time before the vacuum was generated. Line D shows the generation of a vacuum with a vacuum pump according to the invention, where the oxide layer is additionally provided with a seal.

As can be seen from line A, a low final pressure is obtained very quickly with the uncoated pumping element, but this final pressure is not stable due to wear of the pumping element. When the pumping element has an anodic coating, a stable but relatively high final pressure is obtained even after a long run-in phase. This becomes clear from line B. For line B pumps, the test was interrupted after a short run time and a seal was applied to the oxide layer. Continuing the test, one notices that the pressure drops very quickly, achieving a significantly lower final pressure. Line C shows that lower final pressures can be achieved by heating the pumping element as was introduced for line B until the test was interrupted, but even heating fails to remove defects contained in the oxide layer. As can be seen from Figures 17 to 19, therefore, the cracks can cause some backflow of the pumped medium. However, the final pressure achievable is better than when the pumping element is not heated. However, there is also a need for improvement here. The sealed pumping element used with line D allows for significantly lower final pressures than with line B (until test interruption) and line C, where the resulting vacuum is is stable, unlike For lines B and C, significantly longer break-in times are expected to reach lower final pressures. Thus, not only does the seal according to the invention tend to improve the achievable final pressure, but also the break-in time is significantly reduced. This highlights the significant effect obtained on the basis of the sealing of the pore structure of the oxide layer with respect to short running-in times, low final pressures and high wear resistance.

20 scroll pump 22 first housing element 24 second housing element/fixed scroll member 26 scroll wall 28 scroll wall 30 movable scroll member 32 eccentric shaft 34 motor 36 rolling bearing 38 eccentric pin 40 rolling bearing 42 corrugated bellows 44 fan 46 air guide hood 48 electronics housing 50 passageway 52 chamber 54 fins 56 recess 58 fins 60 pressure sensor 62 passageway 64 sealing element 66 base plate 68 retaining projection 70 first intermediate portion 72 second intermediate portion 74 third intermediate portion 76 Clamping device 78 Three-jaw chuck 80 Cavity 82 Balance weight 84 Mounting hole 86 Shaft shoulder 88 Housing shoulder 90 Gas ballast valve 92 Operating grip 94 Plastic body 96 Base element 98 Hole 100 Non-return valve 102 Plug 104 Mounting screw 106 Pivot screw Possible elements 108 hole 110 hole 112 lid 114 groove 116 inner sidewall 118 outer sidewall 120 first scroll portion 122 second scroll portion 124 air flow 126 socket 128 plug 130 partition wall 132 recess 134 intermediate fit 136 O Ring 138 Tear-Away Thread 140 Recess 142 Mounting Screw 144 Dome 150 Seal 152 Slide Layer 154 Support

As can be seen from line A, a low final pressure is obtained very quickly with the uncoated pumping element, but this final pressure is not stable due to wear of the pumping element. When the pumping element has an anodic coating, a stable but relatively high final pressure is obtained even after a long run-in phase. This becomes clear from line B. For line B pumps, the test was interrupted after a short run time and a seal was applied to the oxide layer. Continuing the test, one notices that the pressure drops very quickly, achieving a significantly lower final pressure. Line C shows that lower final pressures can be achieved by heating the pumping element as was introduced for line B until the test was interrupted, but even heating fails to remove defects contained in the oxide layer. As can be seen from Figures 17 to 19, therefore, the cracks can cause some backflow of the pumped medium. However, the final pressure achievable is better than when the pumping element is not heated. However, there is also a need for improvement here. The sealed pumping element used with line D allows for significantly lower final pressures than with line B (until test interruption) and line C, where the resulting vacuum is is stable, unlike For lines B and C, significantly longer break-in times are expected to reach lower final pressures. Thus, not only does the seal according to the invention tend to improve the achievable final pressure, but also the break-in time is significantly reduced. This highlights the significant effect obtained on the basis of the sealing of the pore structure of the oxide layer with respect to short running-in times, low final pressures and high wear resistance.
The present application relates to the invention described in the claims, but includes the following as other aspects.
1.
In pumps, especially vacuum pumps,
a slide layer (152);
the sliding layer (152) has, in particular, an oxide layer formed by anodization in an acid-containing electrolyte and a polymer-based seal, in particular based on a fluorine-containing polymer,
A pump, wherein the oxide layer is at least partially covered by a seal and/or the oxide layer is impregnated with the seal.
2.
the pump is a spiral or scroll pump (20), in particular a spiral or scroll vacuum pump, comprising pumping elements (24, 30) configured as scroll elements;
2. A pump according to claim 1, wherein the slide layer (152) is at least partially applied to at least one of the pumping elements (24, 30) configured as scroll elements.
3.
the pump is a piston pump, in particular a piston vacuum pump, comprising at least one cylinder having an inner wall of the cylinder and a piston movable within the cylinder;
2. A pump according to claim 1, wherein the slide layer is at least partially applied to the cylinder inner wall and/or the piston.
4.
4. The method of claim 1, wherein the oxide layer is porous and the seal at least partially closes pores (160) and/or cracks (158) and/or defects (158) in the oxide layer. A pump according to at least one.
5.
the seal is a polyurethane layer formed from polyurethane with perfluoro segments; and/or
the seal comprises a fluoroalkylsiloxane;
5. The pump according to at least one of 1 to 4 above.
6.
the seal is made of polyurethane with polyether segments; and/or
the seal is made of polyurethane with perfluoropolyether segments;
6. The pump according to at least one of 1 to 5 above.
7.
7. Pump according to at least one of the preceding claims 1 to 6, wherein the sealing portion has a thickness of 10 μm or less, in particular 0.5 μm to 5 μm.
8.
8. A pump according to any one of claims 1 to 7, wherein the sealing portion has a thickness of 5 to 25 μm or 25 to 35 μm.
9.
9. A pump according to at least any one of the above 1 to 8, wherein the sealing portion substantially completely or completely covers the oxide layer.
10.
an adhesion promoter is provided on the seal and/or
an adhesion promoter is provided on the oxide layer as a primer,
10. The pump according to at least one of 1 to 9 above.
11.
11. At least of 1 to 10 above, wherein the pumping element has a base material, the base material being formed at least partially from aluminum or an aluminum alloy, and having a sliding layer (152) applied on the base material. A pump according to any one of the preceding claims.
12.
A method of manufacturing a slide layer (152), comprising:
the steps below
a) forming an oxide layer, in particular by anodization in an electrolyte, preferably containing an acid;
b) coating the oxide layer with the seal;
A method.
13.
13. A method according to Claim 12, wherein the seal is applied in the form of an aqueous dispersion or in the form of a solvent-based dispersion.
14.
14. A method according to claim 13 , wherein the solvent in the solvent-based dispersion is a C ₁ -C ₈ alcohol, especially a C ₃ -C ₆ alcohol, such as a C ₄ alcohol.
15.
15. The method according to any one of 12 to 14 above, wherein the method is a manufacturing method used for the pump according to any one of 1 to 11 above.

Claims (15)

In pumps, especially vacuum pumps,
a slide layer (152);
the sliding layer (152) has, in particular, an oxide layer formed by anodization in an acid-containing electrolyte and a polymer-based seal, in particular based on a fluorine-containing polymer,
A pump, wherein the oxide layer is at least partially covered by a seal and/or the oxide layer is impregnated with the seal. the pump is a spiral or scroll pump (20), in particular a spiral or scroll vacuum pump, comprising pumping elements (24, 30) configured as scroll elements;
2. The pump of claim 1, wherein the slide layer (152) is at least partially applied to at least one of the pumping elements (24, 30) configured as scroll elements. the pump is a piston pump, in particular a piston vacuum pump, comprising at least one cylinder having an inner wall of the cylinder and a piston movable within the cylinder;
2. Pump according to claim 1, wherein the slide layer is at least partially applied to the cylinder inner wall and/or the piston. 4. Claims 1 to 3, wherein the oxide layer is porous and the seal at least partially closes pores (160) and/or cracks (158) and/or defects (158) in the oxide layer. A pump according to at least any one of . the sealing portion is a polyurethane layer formed from polyurethane having perfluoro segments; and/or the sealing portion comprises a fluoroalkylsiloxane;
5. Pump according to at least one of claims 1 to 4. the sealing portion is made of polyurethane with polyether segments; and/or the sealing portion is made of polyurethane with perfluoropolyether segments.
6. Pump according to at least one of claims 1 to 5. 7. Pump according to at least one of the preceding claims, wherein the sealing portion has a thickness of 10 [mu]m or less, in particular 0.5 [mu]m to 5 [mu]m. 8. A pump according to at least any one of claims 1 to 7, wherein the sealing portion has a thickness of 5[mu]m to 25[mu]m or 25[mu]m to 35[mu]m. 9. A pump according to at least one of claims 1 to 8, wherein the sealing portion substantially completely or completely covers the oxide layer. an adhesion promoter is provided on the seal and/or an adhesion promoter is provided on the oxide layer as a primer,
10. Pump according to at least one of claims 1 to 9. 11. The method of claim 1, wherein the pumping element has a base material, the base material being at least partially made of aluminum or an aluminum alloy, on which the sliding layer (152) is applied. A pump according to at least any one of the preceding claims. A method of manufacturing a slide layer (152), comprising:
the following step a) forming an oxide layer, in particular by anodization, preferably in an acid-containing electrolyte;
b) coating the oxide layer with the seal;
A method. 13. A method according to claim 12, wherein the sealing part is applied in the form of an aqueous dispersion or in the form of a solvent-based dispersion. 14. A method according to claim 13, wherein the solvent in the solvent-based dispersion is a C1 _{- C8} alcohol, especially a _C3 - _C6 alcohol, such as a _C4 alcohol. 15. A method according to at least one of claims 12-14, wherein the method is a manufacturing method for use in a pump according to at least one of claims 1-11.

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