Patent Application
20240024983
Embodiments of the present invention relate to a method for laser welding bar-type conductors.
A method has been disclosed by the online publication “STATOR HAIRPINS AUS ALUMINIUM ENTLACKEN UND SCHWEISSEN—GROSSES EINSPARPOTENZIAL” (“Stripping and welding stator hairpins of aluminum—great savings potential”) by Clean-Lasersysteme, Herzogenrath (North Rhine-Westphalia, DE), cf. <www.cleanlaser.de/de/news/hairpins-aluminium/>, dated Mar. 5, 2021.
In the manufacture of electric motors or electronic generators, in addition to wound stators use is also made nowadays of stators which are formed from metallic, usually bent, bar-shaped conductors (“bar-type conductors”), in particular from what are referred to as hairpins. The bar-type conductors are arranged such that they correspond to an intended electrical connection and are then welded to one another in order to form an electromagnet in this way. By contrast to the wound stator, the hairpin technology enables advantages in terms of weight, costs and efficiency.
The bar-type conductors are frequently welded using a laser beam. To that end, the laser beam is typically directed at the front end faces of two overlapping bar-type conductors that often lie against one another. As a result, heat is introduced into the bar-type conductors, the bar-type conductors melt and, after solidifying, the bar-type conductors are connected to one another by a solidified weld bead.
During the welding, it is necessary to create a sufficiently large cross-sectional area by way of which the electric current can flow between the two bar-type conductors. If the welding is not performed correctly, ohmic heating, a loss of effectiveness or an unusable electrodynamic machine can arise during operation.
Up to now, use has been made mainly of bar-type conductors made of copper. An example for the welding of copper-containing bar-type conductors has been disclosed by the subsequently published German patent application 10 2020 113 179.8.
In the aforementioned online publication, the company Clean-Lasersysteme proposes directly processing hairpins of aluminum instead of copper. To that end, the hairpins of aluminum are welded to one another in a vacuum. The use of the hairpin of aluminum should in particular offer cost advantages. Further details regarding the method are not mentioned.
However, the welding of hairpins of aluminum has proven difficult in practice. The weld beads created by a laser beam can easily run during the welding operation, and therefore often an insufficient cross-sectional area for the conduction of current is obtained, and the welding is unusable.
Embodiments of the present invention provide a method for laser welding bar-type conductors. The method includes arranging two bar-type conductors next to one another with a partial overlap, and welding the two bar-type conductors to one another by using a processing laser beam. A weld bead that connects the two bar-type conductors to one another is formed on a common base surface of the bar-type conductors that are next to one another. The common base surface is aligned horizontally. During the welding of the bar-type conductors, the processing laser beam is guided, so that a welding contour of the processing laser beam is placed relative to the bar-type conductors. An advancing rate v of the processing laser beam along the welding contour relative to the bar-type conductors is selected such that, during the welding of the bar-type conductors, the weld bead has a non-liquid oxide skin inside which liquid bar-type conductor material accumulates. The non-liquid oxide skin is partially broken open in a manner corresponding to the welding contour by the processing laser beam only on an upwardly facing end face of the weld bead, and remains undamaged in a surrounding region of the weld bead that extends downward from the upwardly facing end face toward the bar-type conductors and around the entire weld bead.
Subject matter of the present disclosure will be described in even greater detail below based on the exemplary figures. All features described and/or illustrated herein can be used alone or combined in different combinations. The features and advantages of various embodiments will become apparent by reading the following detailed description with reference to the attached drawings, which illustrate the following:
Embodiments of the present invention provide a method for laser welding bar-type conductors of an aluminum-containing alloy, in order to create a usable welded connection with high reliability and in particular to obtain a sufficiently large cross-sectional area for the conduction of current. According to some embb, the bar-type conductors are bent bar-type conductors, in particular hairpins for an electric motor or an electric generator. The bar-type conductors comprise an aluminum-containing bar-type conductor material with an aluminum content of at least 75% by weight, preferably at least 90% by weight. The two bar-type conductors are arranged next to one another with a partial overlap, and are welded to one another by means of a processing laser beam. A weld bead which connects the bar-type conductors to one another is formed on a common base surface of the bar-type conductors that are next to one another, in particular the common base surface being aligned horizontally. According to some embodiments, during the laser welding of the bar-type conductors, the processing laser beam is guided, and in the process a welding contour of the processing laser beam is placed relative to the bar-type conductors and an advancing rate v of the processing laser beam along the welding contour relative to the bar-type conductors is selected, such that,
Embodiments of the invention provide a suitable way of conducting the process of welding two aluminum-containing bar-type conductors to have the effect that a non-liquid oxide layer (“oxide skin”) is formed in the region of the process zone and is kept stable during the welding. Underneath the oxide skin, liquid bar-type conductor material then forms, which is kept in the defined form of a weld bead by the oxide skin. This makes it possible to reliably produce a usable welded connection.
In the case of welding of two metal-containing bar-type conductors, the production of a dimensionally stable weld bead is important since the quality of the weld bead obtained has an effect on the current-conducting properties between the bar-type conductors. Aluminum has considerably lower viscosity and surface tension than copper at the melting temperature. This is why, during welding, the low-viscosity melt of the aluminum-containing alloy tends to run in uncontrolled fashion out of the region of the process zone in which welding is performed. This can lead to a greatly deformed or incompletely formed weld bead and thus a reduced cross-sectional area between the bar-type conductors in which the electric current can flow.
The advantages resulting from the use of aluminum-containing bar-type conductors, like the cost saving already mentioned above but also weight savings (the density of copper in element form, at 8.96 g/cm3, is more than three times the density of aluminum in element form, at 2.7 g/cm3), might then be negated by the disadvantages of a defective or excessively small cross-sectional area between the bar-type conductors.
In the method according to embodiments of the invention, the way of conducting the process is selected such that, during the laser welding of the bar-type conductors, a non-liquid oxide layer (“oxide skin”) is present in the region of the process zone. The oxide skin circumvents the disadvantage of low viscosity and surface tension of the melt of aluminum-containing alloys. The oxide skin keeps the shape of the melt uniform and forms a surrounding region (“lateral surface”) which aligns the melt upward and delimits it to the sides. This produces a uniform weld bead and prevents the melt from running to the sides. The viscosity and surface tension of the melt then no longer matter.
Aluminum stored in air spontaneously forms a thin layer of aluminum oxide (self-passivation), which protects it against corrosion. At the start of the welding method, the bar-type conductor material is thus already covered by an oxide skin, underneath which liquid melt can form and accumulate. During the laser welding, the thickness of the oxide skin can increase compared with the thickness of the oxide skin of the previously solid bar-type conductor, in particular as a consequence of the temperatures reached during laser welding. Furthermore, new aluminum oxide can spontaneously form during the method at locations where molten aluminum is exposed, in particular at locations in the oxide skin that are broken open by the processing laser beam. While the method is being carried out, the oxide skin remains for substantially the entire time to delimit the weld bead which is forming or becoming larger, using the oxide skin present before the start of the laser welding and/or the oxide skin newly formed during the laser welding.
The process is conducted according to embodiments of the invention in such a way that the dynamics of the melt are delimited, in particular close to the surrounding region, and cracks at which melt can exit in uncontrolled fashion, which would result in a non-uniform weld bead, are prevented from forming in the surrounding region. To delimit the dynamics of the melt pool, the processing laser beam may follow the welding contour in particular at a sufficiently low advancing rate. Furthermore, to avoid cracks in the surrounding region of the oxide skin of the weld bead, the welding contour can be selected such that it is sufficiently spaced apart from the periphery of the bar-type conductors (or from the periphery of that side of the bar-type conductors that faces toward the laser beam, the “end face”). The stability of the oxide skin is promoted under these conditions.
In the course of the laser welding of the bar-type conductors, a melt pool is created underneath the oxide skin. This is possible because the melting temperature of aluminum in elementary form, at ≈660° C., is considerably lower than the melting temperature of aluminum oxide, at ≈2070° C. (depending on atmospheric conditions, the processing laser beam can also cause Al2O3 to disassociate instead of melting). The melt pool is heated until the desired volume of liquid aluminum is obtained. This ensures that the cross-sectional area between the bar-type conductors upon final solidification is large enough to obtain a sufficiently high conduction of current.
The processing laser beam interacts with the oxide skin substantially only in the region in which the processing laser beam is incident on the oxide skin. The processing laser beam breaks open the oxide skin only along its welding contour, and therefore the welding contour produces a broken-open (i.e. liquid) track, possibly also with a broken-open (or liquid) region inside the welding contour. In all other respects, the oxide skin is maintained and keeps the molten bar-type conductor material together and in shape.
After the processing laser beam has finished acting, the melt pool, which is still kept in shape by the oxide skin, cools down. Upon solidification, the result is then a defined weld bead in the case of which the connected bar-type conductors have a sufficiently large cross-sectional area and ensure a sufficiently good conduction of current. A usable welded connection is reliably produced.
In an embodiment, it is provided that the welding contour of the processing laser beam is placed relative to the bar-type conductors such that, for a smallest distance d of the welding contour from an outer periphery of the common base surface and an extent L of the common base surface along the direction in which the smallest distance d lies, it holds true that:
A variant is preferred in which the welding contour of the processing laser beam is placed relative to the bar-type conductors such that, for a smallest distance d of the welding contour from an outer periphery of the common base surface, it holds true that:
In an advantageous variant, for the advancing rate v of the processing laser beam along the welding contour of the processing laser beam relative to the bar-type conductors, it holds true that:
A variant in which the laser welding takes place in an oxygen-containing atmosphere, in particular in air, is preferred. The oxygen-containing atmosphere stabilizes the oxide skin of the weld bead and facilitates quick reformation of aluminum oxide on exposed aluminum melt, for instance in the track of the processing laser beam. Moreover, an oxygen-containing atmosphere can be set up easily; in particular when air is used, no additional structures are necessary.
In an embodiment, it is provided that, at least in a chronologically second half of the laser welding of the bar-type conductors, the surrounding region, in which the non-liquid oxide skin remains undamaged, extends over at least ¾ of the height of the weld bead, preferably over at least 9/10 of the height of the weld bead. This ensures the formation of a dimensionally stable and uniform weld bead with a height which sets up an electrical conduction of current, which is sufficient in practice, between the bar-type conductors over the available cross-sectional area of the weld bead. Usually, the surrounding region extends practically over the entire height of the weld bead.
A variant is also preferred in which the two bar-type conductors are arranged with end regions parallel to one another and lying against one another,
What is advantageous is a further development of this variant that provides that the end regions of the bar-type conductors are directed approximately vertically upward,
Also preferred is a further development in which the processing laser beam is incident on the front end faces approximately perpendicularly. This has the effect of a stable vapor capillary, and the melt pool dynamics are reduced. A defined weld bead can be formed more easily.
What is preferred is a variant that provides that the bar-type conductors, at least close to the common base surface, in particular in a respective end region, each have a rectangular cross section with edge lengths between 0.2 mm and 10 mm, preferably between 1 mm and 8 mm, preferably between 2 mm and 6 mm,
Further preferred is a variant which provides that a smallest distance d2 between the welding contour and the outer periphery of the common base surface in the direction of a respective long edge is between 20% and 40%, preferably between 25% and 35%, of the associated long edge length L2, and a smallest distance d1 between the welding contour and the outer periphery of the common base surface in the direction of a respective short edge is between 20% and 40%, preferably between 25% and 35%, of twice the short edge length Li. This involves distances d2 and d1 which have proven successful in practice and with which the probability of damage to the oxide skin is minimized, in particular in the surrounding region.
In an advantageous variant, the processing laser beam has a laser power P, where
0.5 kW≤P≤20 kW,
preferably 2 kW≤P≤10 kW,
preferably 4 kW≤P≤8 kW,
Preferred is a variant in which the welding contour is selected to be linear, circular or elliptical and is traversed multiple times during the laser welding of the bar-type conductors,
Further preferred is a variant in which a shaped laser beam having a core portion and a ring portion, which annularly surrounds the core portion, is at least temporarily selected as processing laser beam,
In a preferred further development of this variant, a power component Pkern of the laser power in the core portion is selected to be smaller during a chronologically first phase of the laser welding of the bar-type conductors than during a main phase of the laser welding of the bar-type conductors,
Similarly preferred is a further development in which a power component Pkern of the laser power in the core portion is selected to be smaller during a chronologically last phase of the laser welding of the bar-type conductors than during a main phase of the laser welding of
A bar-type conductor arrangement comprising at least two bar-type conductors which have been welded by an above-described method according to embodiments of the invention is also covered within the context of the present invention. The weld bead formed during the welding is uniformly shaped and reliably provides a sufficient cross-sectional area for the flow of electric current between the welded bar-type conductors. Typically, a multiplicity of bar-type conductors are welded consecutively (for example in a stator carrier), with the bar-type conductors being welded at both legs to further bar-type conductors (or, in the case of terminal bar-type conductors, to a power connection).
Furthermore, embodiments of the present invention include the use of bar-type conductor arrangements, the bar-type conductor arrangements each being produced by welding two respective bar-type conductors by an above-described method according to embodiments of the invention, and the bar-type conductor arrangements being installed in an electric motor or an electric generator. The welded connections of the bar-type conductors are reliable and therefore also readily suitable for the high current strengths occurring in electric motors and electric generators. In the case of electric motors provided for mobile applications (for instance electric vehicles), the low inherent weight of bar-type conductors of aluminum-containing bar-type conductor material is advantageous.
Further advantages of embodiments of the invention will emerge from the description and the drawing. Likewise, according to embodiments of the invention, the features mentioned above and those yet to be explained further can be used in each case individually by themselves or together in any desired combination. The embodiments shown and described should not be understood as an exhaustive enumeration, but rather are of an exemplary character.
The bar-type conductors 1a, 1b are intended to be electrically conductively connected to each other. For this purpose, according to embodiments of the invention, the bar-type conductors 1a, 1b are welded to one another at their end regions 5a, 5b. For the welding, the leg 3a of the first bar-type conductor 1a and the leg 3b of the second bar-type conductor 1b are arranged with an overlap and, in the variant shown here, lying against one another.
For the bar-type conductors 1a, 1b, use is made of aluminum-containing bar-type conductor materials having an aluminum content of at least 75% by weight, preferably at least 90% by weight. Possible aluminum-containing bar-type conductor materials considered are, for example, aluminum alloy groups of series 1000 to 6000 (for example, material EN AW-1050A).
The two end regions 5a, 5b are to be welded using a processing laser beam 11. To that end, a welding contour 12 is defined on the common base surface 7 that then is to be traversed multiple times by the processing laser beam 11. In the embodiment shown here, the welding contour 12 is selected to be elliptical. It is also possible to select linear welding contours (not shown here) or circular welding contours (see
The processing laser beam 11 is incident on the common base surface 7 approximately perpendicularly. It should be noted that, during the manufacture of different pairs of bar-type conductors 1a, 1b, the angle of incidence of the processing laser beam 11 can typically vary slightly in order not to have to move the bar-type conductors 1a, 1b, which are usually arranged in a stator carrier (not shown in detail), too frequently. The processing laser beam 11 typically does not deviate more than 40°, preferably not more than 20°, from a vertical incidence on the base surface 7.
The laser power P of the processing laser beam 11 may be selected such that 0.5 kW≤P≤20 kW, preferably 2 kW≤P≤10 kW, preferably 4 kW≤P≤8 kW, holds true. This makes it possible to achieve good results in practice. For example, a power P of 6 kW can be used to weld two aluminum-containing bar-type conductors 1a, 1b. The wavelength of the processing laser beam 11 may be between 400 nm and 1200 nm. Examples of this are wavelengths of 450 nm (blue), 515 nm (green), 900±100 nm (diode, NIR), 1030 nm (NIR), 1064 nm (NIR) and 1070 nm (NIR).
The processing laser beam 11 is intended to move along the welding contour 12, which lies on an upper end face 20 of the weld bead 19. This introduces heat into the aluminum-containing bar-type conductor material. In the process, underneath a non-liquid oxide skin 14 a liquid bar-type conductor material 15 (dashed reference line, since the liquid bar-type conductor material 15 is hidden under the non-liquid oxide skin 14), that is to say an aluminum-containing melt, forms and accumulates. The non-liquid oxide skin 14 then forms the boundary of the weld bead 19 and ensures that the shape of the liquid bar-type conductor material 15 is maintained and the liquid bar-type conductor material 15 is prevented from running. The non-liquid oxide skin 14 is locally broken open by the processing laser beam 11, the processing laser beam 11 leaving behind a broken-open track 12a along the welding contour 12 in the variant shown. This exposes temporarily liquid bar-type conductor material along the track 12a in the broken-open region. Behind the processing laser beam 11, the liquid bar-type conductor material 15 starts to oxidize again, with the result that a new oxide skin 14 forms and the track 12a closes up again. In the variant shown, the track 12a extends over approximately ⅓ of the circumference of the welding contour 12 before the non-liquid oxide skin 14 completely grows back over it. The method according to embodiments of the invention typically takes place in an oxygen-containing atmosphere (for example air), and therefore a non-liquid oxide skin 14 can reform by oxidation quickly in the broken-open region.
The non-liquid oxide skin 14 extends in a surrounding region 21 of the weld bead 19 from the upper end face 20 downward to the still-solid end regions 5a, 5b of the bar-type conductors 1a, 1b and around the entire weld bead 19. In the variant shown here, the non-liquid oxide skin 14 is broken open along the welding contour 12, along which the processing laser beam 11 moves, in the region of the track 12a (shown in black). The exposed liquid bar-type conductor material 15 is reoxidized by the oxygen-containing atmosphere (region of the black contour 12 that is not filled out in
The weld bead 19 has an overall height H sp in the z direction (along the direction of extent of the end regions 5a, 5b of the bar-type conductors 1a, 1b), and the surrounding region 21 of the weld bead 19, in which the non-liquid oxide skin 14 remains undamaged, has a height Hunv. The height Hunv generally extends from the lower end of the weld bead 19 to the region in which the processing laser beam 11 moves along the welding contour 12. Since the processing laser beam 11 partially breaks open the non-liquid oxide skin 14 and thus exposes liquid bar-type conductor material 15, that region of the upper end face 20 that is inside the welding contour 12 is no longer considered to be an undamaged part of the surrounding region 21. In the variant shown here, Hunv extends over approximately ⅘ the height of Hsp. It has been shown to be advantageous that the height Hunv should extend over at least ¾ the height of Hsp, preferably over at least 9/10 the height of Hsp, in order that a defined weld bead 19 can form. In many use cases, in the case of a weld bead 19 that has a largely flat form at the end face 20, Hunv extends over practically the entire height Hsp (not shown in detail).
At the end of the welding, after the processing laser beam 11 has finished acting, the liquid bar-type conductor material 15 cools down, continuing to be kept in shape by the non-liquid oxide skin 14, and lastly solidifies. The bar-type conductors 1a, 1b are then electrically conductively connected to one another by the weld bead 19. In the process, the weld bead 19 is placed on both bar-type conductors 1a, 1b and covers them over the entire surface area at their ends. The quality of the electrically conductive connection between the two bar-type conductors 1a, 1b is substantially determined by a connecting cross-sectional area 22. The connecting cross-sectional area 22 is the surface area through which the electrical conduction of current from the first bar-type conductor 1a to the second bar-type conductor 1b is enabled. In the case of the well-defined weld bead 19 shown in
The rectangular front end faces 6a, 6b each have a long edge length L2 and a short edge length Lkurz. The common base surface 7 is described by a long edge length L2 and twice the short edge length Li. It should be noted that a narrow gap is shown between the front end faces 6a, 6b in
The smallest distance, which lies between the welding contour 12 and the outer periphery 18 of the common base surface 7 in the direction of (along) a short edge 17, is referred to as a smallest distance d1. The smallest distance, which lies between the welding contour 12 and the outer periphery 18 of the common base surface 7 in the direction of (along) a long edge 16, is referred to as a smallest distance d2. In practice, it has been shown that the lateral surface of the non-liquid oxide skin generally remains undamaged during the welding if d1 is selected to be between 20% and 40% the length of L1, preferably between 25% and 35% the length of L1, and d2 is selected to be between 20% and 40% the length of L2, preferably between 25% and 35% the length of L2.
Within the context of the method according to embodiments of the invention, it is advantageous to select the processing laser beam 11 as a shaped laser beam 11a, which at least temporarily has a core portion 23 and a ring portion 24.
The shaped laser beam 11a is produced, for example, by a 2-in-1 fiber 27;
A power component Pkern in the core portion and a power component P ring in the ring portion can be set in that an original laser beam is partially fed into the core fiber 25 and partially into the ring fiber 26, for example via an optical wedge (not shown in detail) which is partially pushed into the original laser beam. Within the context of the embodiments of the invention, the power distribution between the core portion and the ring portion can be selected to be constant, or else can be varied, throughout the duration of the laser welding of the bar-type conductors. Typically, Pkern is between 20% and 100%, preferably between 20% and 80%, preferably between 40% and 60% of a total laser power Pges of the processing laser beam. Modifying the components of the original laser beam that are fed into the core fiber 25 and the ring fiber 26, for example by shifting the optical wedge (not shown in more detail), makes it possible to vary the power components Pkern, Pring. Typically, the total laser power Pges=Pkern+Pring is selected to be constant throughout the welding duration.
In an advantageous variant of the laser welding according to embodiments of the invention, which is illustrated in
The laser welding of the two bar-type conductors comprises a first phase (initial phase) EP, a main phase HP and a last phase (final phase) LP, during which movement occurs along the welding contour (for example, an elliptical path or circular path being traversed multiple times). The advancing rate can be selected here typically to be constant throughout the welding duration GD. In the chronologically first phase EP (between the points in time t0 and t1) and in the chronologically last phase LP (between the points in time t2 and t3) of the laser welding of the bar-type conductors, a power component Pkern of the laser power in the core is selected to be lower than in the main phase HP in between (between the points in time t1 and t2).
Upon penetration of the shaped laser beam 11a at the start of the chronologically first phase EP (at the point in time t0), the low laser power in the core Pkern reduces spatter formation and thus prevents relatively large amounts of non-liquid oxide skin (and liquid melt) from being flung out. The power component in the core Pkern starts here at 30% and then increases in the chronologically first phase EP (in this instance linearly) until it has reached a desired value for the main phase HP. For example, the selection of the duration of the first phase EP may depend on whether the vapor capillary produced by the shaped laser beam has reached a certain capillary depth (for example 30% of its maximum capillary depth). The chronologically first phase EP of the laser welding often comprises a component of 10-30% of the total welding duration GD of the welding of the two bar-type conductors and can last, for example, between 1 ms and 30 ms.
In the main phase HP (between the points in time t1 and t2), movement is then performed again along the welding contour 12 with the desired component of the laser power in the core Pkern. In the variant shown, Pkern is 100% in the main phase, that is to say that the ring component is not illuminated; alternatively, it would also be possible to select Pkern to be for example between 60% and 90%.
After the main phase HP (from the point in time t2), the component of the laser power in the core Pkern is reduced again (in this case linearly) until it reaches a desired value (in this case in turn 30%). The effect achieved by this is that the vapor capillary produced by the shaped laser beam uniformly recedes, as a result of which only a few pores, if any at all, are obtained in the cooled bar-type conductor material. The chronologically last phase LP of the laser welding often comprises a component of 10-30% of the total welding duration GD of the welding and can last, for example, between 1 ms and 30 ms.
By contrast,
While subject matter of the present disclosure has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. Any statement made herein characterizing the invention is also to be considered illustrative or exemplary and not restrictive as the invention is defined by the claims. It will be understood that changes and modifications may be made, by those of ordinary skill in the art, within the scope of the following claims, which may include any combination of features from different embodiments described above.
The terms used in the claims should be construed to have the broadest reasonable interpretation consistent with the foregoing description. For example, the use of the article “a” or “the” in introducing an element should not be interpreted as being exclusive of a plurality of elements. Likewise, the recitation of “or” should be interpreted as being inclusive, such that the recitation of “A or B” is not exclusive of “A and B,” unless it is clear from the context or the foregoing description that only one of A and B is intended. Further, the recitation of “at least one of A, B and C” should be interpreted as one or more of a group of elements consisting of A, B and C, and should not be interpreted as requiring at least one of each of the listed elements A, B and C, regardless of whether A, B and C are related as categories or otherwise. Moreover, the recitation of “A, B and/or C” or “at least one of A, B or C” should be interpreted as including any singular entity from the listed elements, e.g., A, any subset from the listed elements, e.g., A and B, or the entire list of elements A, B and C.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2021 109 623.5 | Apr 2021 | DE | national |
This application is a continuation of International Application No. PCT/EP2022/059224 (WO 2022/218804 A2 and WO 2022/218804 A3), filed on Apr. 7, 2022, and claims benefit to German Patent Application No. DE 102021109623.5, filed on Apr. 16, 2021. The aforementioned applications are hereby incorporated by reference herein.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/EP2022/059224 | Apr 2022 | US |
| Child | 18482039 | US |
