Abstract
The invention relates to an electrical conductor (1), which is designed as a stranded conductor and comprises a bundle of a plurality of electrically conductive individual wires (3), the individual wires (3) being connected to each other by a cured filler (5) to form a superordinate conductor structure and the conductor (1) having at least one internal coolant channel (9), which runs in a longitudinal direction of the conductor (1) and is sealed fluid-tight from the regions (11) of the stranded conductor that lie further outward, the distance (d) between coolant channel (9) and the closest individual wires (3) of the bundle being at most 1 mm. The invention further relates to an electrical coil device (21) having a conductor (1) of this type and to a method for producing a conductor (1) of this type.
Claims
1. An electrical conductor that is configured as a stranded conductor and comprises: a bundle comprising a number of electrically conductive individual wires, wherein the number of electrically conductive individual wires are connected to one another by a cured filler that fills cavities between the number of electrically conductive individual wires, such that a superordinate conductor structure is formed; and at least one internal coolant duct that extends along a longitudinal direction of the electrical conductor and is sealed off in a fluid-tight manner from regions of the stranded conductor that are situated further on an outside, wherein a distance between the at least one internal coolant duct and closest individual wires of the number of electrically conductive individual wires of the bundle is at most 1 mm.
2. The electrical conductor of claim 1, further comprising a pipe wall between the bundle and a coolant duct of the at least one internal coolant duct, wherein the pipe wall delimits the coolant duct in a fluid-tight manner and has a thickness of at most 1 mm, and wherein a filling from a region in an interior of the pipe wall is removed, such that the coolant duct is formed.
3. The electrical conductor of claim 2, wherein a material of the pipe wall has a thermal conductivity of at least 5 W/m.Math.K.
4. The electrical conductor of claim 2, wherein a material of the pipe wall is an electrically conductive material, comprises a thermally conductive plastic, comprises a thermally conductive composite material, or any combination thereof.
5. The electrical conductor of claim 1, wherein the at least one internal coolant duct is delimited directly by the bundle that is connected by the cured filler, so that the at least one internal coolant duct is sealed off in a fluid-tight manner by a composite comprising individual wires of the number of electrically conductive individual wires and the filler.
6. The electrical conductor of claim 1, wherein the number of electrically conductive individual wires within the bundle are stranded, braided, or stranded and braided with one another.
7. The electrical conductor of claim 1, wherein the at least one internal coolant duct comprises a plurality of internal coolant ducts.
8. The electrical conductor of claim 1, wherein the number of electrically conductive individual wires within the bundle are pressed together, such that a stable and compact composite is formed.
9. The electrical conductor of claim 1, wherein the electrical conductor is configured as a prefabricated, dimensionally stable conductor segment for a coil device.
10. The electrical conductor of claim 1, wherein the electrical conductor is configured as a malleable conductor for winding an electrical coil.
11. An electrical coil device comprising: an electrical coil winding comprising: one or more electrical conductors, an electrical conductor of the one or more electrical conductors being configured as a stranded conductor and comprising: a bundle comprising a number of electrically conductive individual wires, wherein the number of electrically conductive individual wires are connected to one another by a cured filler that fills cavities between the number of electrically conductive individual wires, such that a superordinate conductor structure is formed; and at least one internal coolant duct that extends along a longitudinal direction of the electrical conductor and is sealed off in a fluid-tight manner from regions of the stranded conductor that are situated further on an outside, wherein a distance between the at least one internal coolant duct and closest individual wires of the number of electrically conductive individual wires of the bundle is at most 1 mm.
12. The electrical coil device of claim 11, wherein the electrical coil winding is configured as a hairpin winding.
13. A method for producing an electrical conductor, the method comprising: arranging a bundle of individual wires around at least one internal elongate core; jointly pressing the bundle of individual wires and the at least one internal elongate core, such that a composite that is stable and compact is formed; filling the composite with a filler and then curing the filler; and forming a coolant duct, forming the coolant duct comprising removing at least a portion of the at least one internal elongate core.
14. The method of claim 13, wherein forming the coolant duct comprises removing an entire core of the at least one internal elongate core or removing an internal portion of the core using a physical, chemical, or physical and chemical process.
15. The method of claim 13, wherein the at least one internal elongate core comprises an external casing and an internal filling (15), and wherein forming the coolant duct comprises removing only the filling, such that the external casing remains as a pipe wall between the coolant duct and the bundle of individual wires.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0050] FIG. 1 shows a schematic perspective illustration of a conductor according to a first exemplary embodiment, after method act c);
[0051] FIG. 2 shows an illustration of the conductor of FIG. 1 after method act d);
[0052] FIG. 3 shows a schematic cross-sectional illustration of a conductor according to a second exemplary embodiment, after method act c);
[0053] FIG. 4 shows a cross-sectional illustration of the conductor of FIG. 3 after method act d);
[0054] FIG. 5 shows a schematic perspective illustration of a conductor according to a third exemplary embodiment;
[0055] FIG. 6 shows a schematic longitudinal section through a terminal region of a conductor according to a fourth exemplary embodiment;
[0056] FIG. 7 shows a schematic longitudinal section of an electrical coil device according to a further example;
[0057] FIG. 8 shows an illustration of a detail of the right-hand-side contact region of a coil device of FIG. 7;
[0058] FIG. 9 shows a schematic cross-sectional illustration of a stator slot with a plurality of conductors; and
[0059] FIG. 10 shows a schematic cross section of a further coil device.
DETAILED DESCRIPTION
[0060] In the figures, elements that are the same or have a same function are provided with the same reference signs.
[0061] FIG. 1 shows a schematic perspective illustration of an electrical conductor 1 (e.g., a conductor) according to a first exemplary embodiment. FIG. 1 shows an intermediate product of the conductor 1 after carrying out acts a), b), and c) of a production method. This conductor 1 has a bundle including a large number of individual wires 3 that are arranged around an internal, elongate core 7 (e.g., a core or an internal core). These individual wires 3 have been pressed together with the internal core 7 to form a stable and compact composite. The conductor composite formed in this way has been filled with a filler 5, and the filler 5 has been cured. A mechanically stable conductor composite that has a rectangular cross section in the example shown was produced in this way. However, this cross-sectional shape is merely exemplary and in general may be chosen as desired. The filler 5 is chosen such that the conductor composite is fluid-tight after the filler 5 is filled and cured. However, the filler 5 may be so flexible that the entire conductor composite may still be bent even after the filler 5 is cured. However, as an alternative, the filler 5 may also be chosen such that the entire conductor composite is dimensionally stable after the curing and may no longer be moved without destruction.
[0062] The internal core 7 has been placed, as, for example, a core rod, between the individual wires 3 of the conductor composite before the pressing. In this example, this core 7 is formed completely from a material with a comparatively low melting point. This has the effect that the core 7 may be melted out of the intermediate product according to FIG. 1 by a comparatively small increase in temperature. Melting out in this way may be performed, for example, by heating the entire conductor composite and/or by flushing out by a flushing liquid (e.g., optionally heated). FIG. 2 shows the finished conductor after removal of the internal core rod 7 in this way. There is now an elongate coolant duct 9 (e.g., a coolant duct) in a center of the conductor 1, rather than the core 7, which was previously present. In the example shown, this coolant duct 9 directly adjoins the composite of individual wires 3 and the filler 5. In other words, the coolant duct 9 directly adjoints the composite of individual wires 3 and the filler 5 without an additional pipe wall. Fluid-tight sealing of the coolant duct 9 is achieved by, for example, the fluid-tight properties of the filler 5 that fills the intermediate spaces between the individual wires 3 in a fluid-tight manner. As a result, the coolant duct 9 is sealed off to such an extent that regions 11 of the conductor 1 that are situated further on an outside cannot be reached by a liquid coolant flowing in the coolant duct 9.
[0063] FIG. 3 shows a schematic cross-sectional illustration of a similar electrical conductor 1 according to a second exemplary embodiment. An intermediate product of the conductor 1 after carrying out method acts a), b), and c) is shown here too. In this case too, the conductor has a bundle including a large number of individual wires 3 that are arranged around an internal core 7 and are pressed together with the core 7 to form a compact composite. Here too, the intermediate space between the individual wires is filled by a cured filler 5 that may optionally be configured in a fluid-tight manner. In contrast to the example of FIG. 1, the internal conductor 7 is not formed from a homogeneous material, but rather, the internal conductor 7 has a concentric structure including an external casing 13 and an internal filling 15. The external casing 13 accordingly forms a pipe wall that is filled with the internal filling 15. In this case, a thickness d of the pipe wall is chosen to be comparatively thin. For example, the thickness d is chosen to be so thin that compression forces F that act toward an inside when the conductor is pressed would compress a region within the pipe wall 13 if the pipe wall 13 were not filled with the filling 15. However, since the filling 15 is present, relatively high compression forces F may be applied when this conductor is pressed, so that a particularly compact conductor composite with a particularly high fill factor of individual wires 3 may be realized. This fill factor is not illustrated approximately true to scale in the illustration of FIG. 3 (e.g., the surface area proportion of the material of the individual wires in the entire cross section may be substantially greater than illustrated). For example, the individual wires may even form a major proportion of the entire cross-sectional area.
[0064] FIG. 4 shows a similar cross-sectional illustration of the conductor 1 of FIG. 3 after the internal filling 15 has been removed. This filling may once again be removed either by melting and/or by being dissolved out using a solvent. Therefore, in this example too, the conductor 1 that is produced in this way has an internal coolant duct 9 through which a liquid coolant may flow for the purpose of cooling the conductor. However, in contrast to the preceding example, the coolant duct 9 is delimited by the stationary pipe wall 13 with the thickness d. This pipe wall 13 may already seal off the internal coolant duct 9 in a fluid-tight manner. As an alternative or in addition, the filler 5 may likewise be configured in a fluid-tight manner here too.
[0065] For example, when a relatively soft material is used for the filling 15 to be removed, the additional pipe wall 13 shown in FIGS. 3 and 4 may be advantageous in order to nevertheless achieve strong compression and therefore a correspondingly high fill factor when the conductor is pressed. Owing to the surrounding pipe wall 13, ingress of the soft filling 15 into the intermediate spaces between the individual wires 3 may also be avoided in the case of strong compression.
[0066] FIG. 5 shows a schematic perspective illustration of a conductor 1 according to a third exemplary embodiment. In contrast to the two preceding examples, this conductor 1 has a plurality of internal coolant ducts 9. Three internal coolant ducts 9 of this kind are illustrated by way of example in the conductor shown, but this number may also be considerably higher. In this case, these coolant ducts 9 may be sealed off from the other regions of the conductor once again either without an additional pipe wall, as in FIG. 2, or with an additional pipe wall 13 for each coolant duct, as in FIG. 4.
[0067] FIG. 6 shows a schematic longitudinal section through an end region of a conductor 1 according to a fourth exemplary embodiment (e.g., with a sectional plane parallel to the longitudinal direction of the conductor). The conductor 1 also has a bundle of individual wires 3 that surround an internal coolant duct 9 on all sides. Three individual wires 3 of this kind are shown on each side of the cross section (e.g., above and below the coolant duct 9). However, these are each also representative of a substantially larger number of individual wires of this kind in the entire conductor.
[0068] These individual wires 3 are each surrounded by an electrically insulating insulation material 17 (e.g., optional) over the major portion of the length of the electrical conductor 1. The individual wires that are insulated in this way are once again jointly embedded into a filling material 5. The filling material may either have been cast as potting agent in a potting process around the individual wires 3 that were previously pressed together, or the filling material may have been applied around the individual wires 3 as the impregnation agent in an impregnation process. In any case, the filling material 5 has been cured after being introduced between the individual wires 3, so that the electrical conductor is provided with increased mechanical strength and dimensional stability as a result. Both insulation material 39 and also filler 40 have been removed from the end region 19 shown in which the electrical conductor 1 may be contacted; however, these are both optional. The individual wires 3 of the conductor may now be electrically connected (e.g., by crimping, welding, or soldering) to a further conductor segment of this kind and/or an external electrical circuit via an electrical contact point in this region. The individual wires 3 of the stranded conductor are twisted or stranded together over the length of the stranded conductor, but this is not shown in FIG. 6 for reasons of clarity.
[0069] In the example of FIG. 6, the internal coolant duct 9 is not delimited by an additional pipe wall. Rather, the coolant duct 9 is delimited directly by the individual wires 3 of the stranded conductor 1 or conductor insulation 17 of the individual wires 3 that are connected to the filler 5. The duct 9 may therefore locally adjoin either the wires 3, as illustrated in the lower portion of FIG. 6, or the duct 9 may locally adjoin the filler 5, as illustrated in the upper portion of FIG. 6. The intermediate spaces between the individual wires 3 are sealed off in a fluid-tight manner by the filler 5, so that the regions of the conductor 1 that are situated further on the outside and, for example, the area surrounding the outside of the conductor may not be reached by a coolant flowing in the coolant duct 9. Supply or discharge of coolant into or from this duct 9 may be performed by the terminal openings 9a in the corresponding end regions 19 of the conductor 1.
[0070] FIG. 7 shows a schematic longitudinal section through an electrical coil device 21 according to a further example. The coil device 21 may be, for example, a portion of a stator winding of an electrical machine. The stator winding is constructed as a hairpin winding, and the detail of FIG. 7 shows two electrical conductors 1 that are each configured as a hairpin segment and together form a hairpin-shaped structure. The longitudinal section shown in FIG. 7 is a sectional illustration with a sectional plane parallel to the main axis of the machine or of the stator. In the central region 27 (e.g., an axially internal region) of the stator, the two hairpin segments each have relatively long straight conductor sections 33 that extend in the axial direction. In this central region 27, the stator has a soft-magnetic yoke 29, into the slots of which axial conductor sections 33 are embedded. Each of the conductors 1 shown has in each case two kinks 31 in end regions adjoining the conductors 1. There is a respective inclined conductor section 35, by way of which the distance (e.g., in the circumferential direction) between the individual axial conductor segments may be bridged, between these two kinks 31 on each side. There are still short contact regions 37, in each of which adjacent hairpin segments may be electrically contacted with one another, in axial end regions 19a and 19b that adjoin the inclined conductor sections.
[0071] As indicated by arrows 23 and 25, a coolant flow from left to right takes place through each of the conductor segments 1 shown. In other words, coolant is fed into the internal coolant ducts 9 of the individual conductors 1 in the end region of the stator that is illustrated on the left-hand side. In contrast, coolant is conducted out of these coolant ducts again 9 in an axial end region of the stator that is illustrated on the right-hand side. The feeding-in in the part of the stator that is illustrated on the left-hand side may be performed, for example, for the individual conductor segments jointly out of a superordinate end-winding chamber. In the portion of the stator that is illustrated on the right-hand side, the coolant again exits from the coolant ducts 9 owing to the excess pressure and may accordingly be collected and supplied to the coolant circuit again as desired.
[0072] The individual hairpin segments 1 from the example of FIG. 7 may be produced, for example, as prefabricated, dimensionally stable conductor segments, where the filler 5 used may be so hard that the individual conductor segments 1 may no longer be bent after the filler is cured. In other words, the shaping at the kinks 31 shown may be performed after the conductor is pressed, but before the filler 5 is cured, here. The internal core material (or at least the filling of the core) may be removed for the purpose of forming the coolant ducts 9 after the conductors are shaped and after the filler is cured.
[0073] FIG. 8 shows a detail of the electrical coil device 21 from FIG. 7. More specifically, FIG. 8 shows a detail in an area surrounding the contact regions 37 illustrated on the right-hand side. In order to be able to electrically connect the two conductor segments 1 shown in the end regions 19b thereof to form a superordinate coil, the corresponding contact regions 37 are enclosed together by a sleeve 41 and pressed together with this sleeve between two opposite plungers 43 that may be energized. Owing to the corresponding pressure (as indicated by the double arrows) and a current flow between the two plungers 43, the two contact regions 37 of the two conductors 1 may be electrically connected to one another either by pure hot-pressing or crimping and/or via an additional welding or soldering layer, not illustrated in any more detail here. Owing to the heating and the pressing by the two plungers 43, the individual wires of the stranded conductors are fused together within the contact regions 37, so that there is no longer any actual stranded conductor in these end regions. In order to nevertheless keep the end regions of the coolant ducts 9 open during this contacting process, suitable mandrels may be inserted into the openings of the ducts during the heating and pressing. FIG. 8 shows, by way of example, how a protective element 45 with two suitable mandrels 47 is temporarily inserted into the two conductor ends such that the two duct openings are kept open. After this supporting element 45 is removed, the two corresponding duct openings may each be provided with a suitable hydraulic fitting in order to either feed in or conduct out coolant or flushing liquid here.
[0074] The described process of keeping the duct openings free by the protective element 45 may be performed, in principle, before or after the core material is removed (e.g., before or after the coolant duct is exposed) in the remaining portion of the conductor length. In other words, the coolant ducts in the conductors 1 may already be exposed before the contacting, and the protective element 45 then protects the end regions that are under heavy loading during the contacting. Alternatively, the material to be removed is removed (e.g., by local heating or immersion into a heated flushing liquid), for example, only in the end regions in a first act, the end regions are contacted after the protective element 45 is attached, and the coolant duct 9 is only then exposed in the rest of the conductor region by removing the core material or a portion of the core material).
[0075] FIG. 9 shows a sectional illustration of a portion of an electrical coil device according to a further example. FIG. 9 shows a region of a stator slot 51 that represents a subregion of a superordinate stator winding. The stator slot 51 is a slot in a soft-magnetic stator yoke 29 into which a plurality of conductor elements are embedded. In the example shown, five conductor elements of this kind are arranged in a manner distributed over three layers. In this case, the size and cross-sectional shape of the individual conductor elements is chosen such that the slot volume may be filled to an optimum extent. To this end, the conductor elements may accordingly have beveled side faces that are configured to match the inclined slot walls. According to the present embodiments, each conductor element has at least one coolant duct 9 that is embedded into the stranded bundle in order to effectively cool the conductors. The conductor element that is furthest on the inside in the radial direction r even has two internal coolant ducts 9 by way of example.
[0076] FIG. 10 shows a schematic cross-sectional illustration of an electrical coil device 29 according to a further example of the present embodiments. FIG. 10 shows a toothed coil in which an electrical conductor is wound in several turns about a coil former 61. The coil former 61 may be formed from a soft-magnetic material and, as in the example of FIG. 10, have a dog bone-shaped cross-sectional profile. In this example too, the electrical conductor is produced by way of a stranded bundle having been arranged around an internal core and pressed together with the internal core. The stranded bundle is then filled, for example, with a filler 5, and the filler 5 is cured. However, the intermediate product produced in this way is still flexible enough in order to wind up the toothed coil according to the shape illustrated in FIG. 10. However, as an alternative, the coil winding may also have been wound from a pressed conductor that did not yet contain any filler, where an impregnation agent that simultaneously serves as a filler for the stranded composite is applied during the winding operation. This impregnation agent may have been cured during the winding operation or after the winding operation.
[0077] In the example of FIG. 10, the removal of at least a portion of the internal core 7 for forming the internal coolant duct takes place only after the coil winding is shaped in each case. FIG. 10 shows how the internal coolant duct 9 is exposed by way of a material of the internal core, which has a low melting point, being flushed out by a flushing liquid. The flushing liquid may be, for example, a preheated flushing liquid that is flushed through the coil arrangement in accordance with the direction of the arrows 73 and 75, and in this way, removes the readily fusible core material from the interior of the conductor. In order to facilitate this removal and therefore the formation of the coolant duct 9, a current flow through the conductor 1 is also generated by two electrical contact elements 63. As a result of this, the conductor is heated, and the core material that has a low melting point is simultaneously melted out and flushed out. In principle, the manner of melting out and flushing out illustrated here may be carried out for all the described types of electrical conductors and for all shapes of electrical coil devices. This applies irrespective of whether there is an additional pipe wall or not, whether the conductor is still movable after the filler is cured or not, and also irrespective of whether the shaping of the conductor for forming the coil is performed before or after the core material in question is removed.
[0078] The elements and features recited in the appended claims may be combined in different ways to produce new claims that likewise fall within the scope of the present invention. Thus, whereas the dependent claims appended below depend from only a single independent or dependent claim, it is to be understood that these dependent claims may, alternatively, be made to depend in the alternative from any preceding or following claim, whether independent or dependent. Such new combinations are to be understood as forming a part of the present specification.
[0079] While the present invention has been described above by reference to various embodiments, it should be understood that many changes and modifications can be made to the described embodiments. It is therefore intended that the foregoing description be regarded as illustrative rather than limiting, and that it be understood that all equivalents and/or combinations of embodiments are intended to be included in this description.
