ARRANGEMENT OF ELECTRICAL CONDUCTORS AND METHOD FOR MANUFACTURING AN ARRANGEMENT OF ELECTRICAL CONDUCTORS

Abstract

The invention relates to an arrangement of electrical conductors, comprising a conductor bundle having at least one individual electrical cable and at least one cooling line through which a cooling fluid is to flow. In order to thermally connect the conductor bundle to the at least one cooling line, a portion of the at least one cooling line and the conductor bundle are embedded in a low melt temperature metal, wherein an insulating sheath of the at least one individual cable is embodied as plastic insulation, preferably as polyimide insulation or as polyester insulation. The invention further relates to a method for manufacturing such an arrangement.

Claims

1. An arrangement of electrical conductors, comprising a conductor bundle having at least one individual electrical cable; and at least one cooling line through which a cooling fluid is to flow, wherein in order to thermally connect the conductor bundle to the at least one cooling line, a portion of the at least one cooling line and the conductor bundle are embedded in a low melt temperature metal; and wherein the insulating sheath of the at least one individual cable is embodied as plastic insulation.

2. The arrangement of electrical conductors according to claim 1, wherein the plastic insulation is a polyimide insulation or a polyester insulation.

3. The arrangement of electrical conductors according to claim 1, wherein the conductor bundle is permanently positively bonded to the portion of the at least one cooling line by casting with the low melt temperature metal.

4. The arrangement of electrical conductors according to claim 2, wherein the polyimide insulation is a sheath of extruded Kapton or wherein the polyester insulation is a polyester lacquer insulation.

5. The arrangement of electrical conductors according to claim 1, wherein the low melt temperature metal has a melting point below one of 260 C. or 150 C.

6. The arrangement of electrical conductors according to claim 1, wherein the arrangement is configured as an electrical or electromagnetic liquid-cooled coil in which the conductor bundle having the at least one individual electrical cable forms at least one winding of the coil.

7. The arrangement of electrical conductors according to claim 6, wherein a hollow torus-shaped coil form, surrounding the at least one winding and the embedded portion of the cooling line, as the carrier of said at least one winding.

8. The arrangement of electrical conductors according to claim 1, wherein the electrical conductors of the individual cables are copper wires.

9. The arrangement of electrical conductors according to claim 1, wherein the low melt temperature metal is one of a tin-bismuth alloy, a tin-lead alloy and a soldering alloy.

10. The arrangement of electrical conductors according to claim 1, wherein the low melt temperature metal contains at least one metal or one allot selected from the group tin, tin-lead, tin-zinc and tin-bismuth.

11. A method for manufacturing an arrangement of electrical conductors according to claim 1, wherein embedding of the conductor bundle and the portion of the at least one cooling line in the low melt temperature metal is carried out by means of a vacuum casting process.

12. A method for manufacturing an arrangement according to claim 6, wherein the coil form is designed to be vacuum-tight, the method comprising the following steps of the vacuum casting process: Arranging of an inflow tube and an outflow tube on the coil form; Plugging of the inflow tube with a low melt temperature metal; Evacuating of the coil form via the outflow tube; Melting of the low melt temperature metal in the inflow tube which is dipped into a reservoir of low melt temperature metal such that, after melting of the low melt temperature metal in said inflow tube, molten low melt temperature metal, driven out of the reservoir by vacuum forces, flows into the hollow space of the coil form.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0028] To avoid repetition, any features disclosed purely in accordance with the device shall be deemed disclosed and claimable also as part of the manufacturing process. Further details and advantages of the invention are described in the following with reference to the associated drawings. The drawings show:

[0029] FIG. 1 a schematic sectional view through a portion of the coil according to an embodiment of the invention;

[0030] FIG. 2 a perspective view of a coil, wherein for illustration purposes a quarter of the outer body and the LMTM filling have been omitted;

[0031] FIG. 3 a flow diagram to illustrate the steps of the manufacturing process; and

[0032] FIG. 4 a schematic perspective view of the coil according to a further embodiment of the invention.

DETAILED DESCRIPTION

[0033] The following Figures describe a water-cooled coil as a highlighted application example of the invention and its manufacturing process. Identical or functionally equivalent elements are denoted by the same reference numbers in all Figures.

[0034] FIGS. 1 and 2 schematically illustrate an embodiment of the water-cooled coil. The coil 1 comprises an outer body 6 of copper which is hollow torus-shaped. FIG. 1 shows a cross section along the sectional plane A-A of FIG. 2 to illustrate a meridian of the torus, while FIG. 2 shows a perspective view of the coil 1 in which an eighth of the outer body 6 and the low melt temperature metal 5 at this point were omitted to make the inner structure clear.

[0035] It can be seen in FIGS. 1 and 2 that a circular portion 4 of the cooling line through which a cooling fluid, preferably water, is to flow, runs in the centre of the internal hollow space formed by the coil outer body 6. The portion 4 of the cooling channel is formed by a single winding of a hollow copper pipe with a diameter of 3 mm. Water enters the circular line portion 4 via an inflow line 4a and is routed out of the coil form 6 again via an outflow line 4b. The remainder of the cooling circuit, which is designed in the manner known per se, is not illustrated.

[0036] Arranged around the water cooling tube 4 are a plurality of windings of a copper wire such that in the illustration in FIG. 2 the circular line portion 4 of the cooling tube is largely covered by the windings. There are 60 windings in the present example. The windings thus consist of individual cables 2 whose electrical conductors are formed from copper wires which are sheathed with a polyimide insulation or a polyester insulation 3. The individual cables 2 or windings are permanently positively bonded to the circular portion 4 of the cooling line by casting with a low melt temperature metal (LMTM) 5. The LMTM 5 thus fills in all the interstitial spaces between the cables and the portion 4 of the cooling line and thus conducts the heat of the individual cables 2 created during operation of the coil to the portion 4 of the cooling line through which water flows when the coil is operating.

[0037] It should be emphasised that FIGS. 1 and 2 merely show a schematic diagram and the actual distances between the windings are smaller than actually illustrated. The diameter of the individual cables 3, for example, is 1.2 mm in the present embodiment while the diameter of the cooling line is 4 mm. These details are merely by way of example and can be modified according to the coil depending on the area of application.

[0038] FIG. 2 additionally shows the two electrical connection cables 2a for supplying the windings with current. In the present embodiment, extruded Kapton was used as an example of a polyimide insulation. According to the manufacturer's data, the maximum target operating temperature of the Kapton wire is 230 C. and therefore significantly below the melting temperature of the tin-bismuth alloy used. The Kapton insulation is thus not damaged when a molten tin-bismuth alloy is introduced.

[0039] A polyester lacquer insulation of the type W210 by Stefan Maier GmbH was used as a polyester example. A tin-bismuth alloy, which was introduced into the coil form 6 using a vacuum casting process, was used as the LMTM 5.

[0040] Such water-cooled coils are used in different technical fields, for example, physics experiments, compact high-power transformers or various compact actuator devices.

[0041] An advantageous manufacturing process of the coil 1 is described in greater detail below based on FIG. 3.

[0042] The coil form 6 is prepared for the vacuum casting process in step S1. In this case, the windings of the individual cables 2 described above and the circular portion 4 of the cooling tube are introduced into the hollow space of the coil outer body 6. For this purpose, the coil outer body 6 can be formed, for example, from two half-shells, which are placed around the individual cables 2 and the cooling tube portion 4, and are joined together vacuum-tight by soldering. The coil outer body 6 has through-holes for the inflow line and the outflow line 4b of the cooling circuit. In addition, an inflow tube 7 (see FIG. 4) and an outflow tube 8 are attached to the coil form 6. The outflow tube 8 is also used as a drain tube for a connected low-vacuum pump.

[0043] The opening of the inflow tube 7 was narrowed to an approximately 1 mm.sup.2 gap such that the LMTM flow rate (see step S6) is reduced by one to two orders of magnitude and to approximately one litre per minute. It is possible thereby to ensure that the LMTM flows in and out in a controlled manner during the casting step and does not reach the connected low-vacuum pump but rather instead plugs the drain tube 8 once the coil form 6 has been completely filled. As a result, vacuum bubbles in the coil and damage to the low-vacuum pump can be prevented.

[0044] Subsequently, in step S2, the inflow tube 7 is sealed by dipping the inflow tube 7 into a small quantity of the LMTM, here a tin-bismuth alloy. The molten tin-bismuth alloy then solidifies in the inflow tube 7 and plugs it. Then in step S3, the drain tube 8 is connected to a low-vacuum pump and the coil form 6 is evacuated using the coil winding, i.e. it is pumped dry with the low-vacuum pump.

[0045] The previously plugged opening of the inflow tube 7 is then dipped in step S5 into a reservoir containing the LMTM in the molten state. In addition, the coil is heated by supplying it with current to a temperature of up to 140 C., i.e. a temperature which is slightly above the melting temperature of the LMTM, in this case 132 C. As a result, the plug of the inflow tube 7 made of the LMTM material melts such that the LMTM from the reservoir, driven by the vacuum forces, now flows via the no longer blocked inflow tube 7 into the interior of the coil form 6 and completely fills it such that the windings of the individual cables 2 and the cooling tube 4 in the interior of the coil form 6 are completely embedded with the LMTM and as a result are thermally joined to each other. The coil is then cooled so that the LMTM becomes solid (step S6).

[0046] The separation between the evacuation of the inner volume of the coil form 6 (step S3) and the subsequent pouring in of the molten LMTM (step S6) reliably prevents the formation of air bubbles and improves the heat transfer from the coil to the cooling line and therefore into the cooling fluid.

[0047] FIG. 4 shows the coil 1 from FIG. 2 with the difference that, as already mentioned above, the inflow tube 7 and the outflow tube 8 are additionally provided on the coil outer body 6 and can be removed after the casting process is discharged.

[0048] Although the invention has been described with reference to particular embodiments, it is apparent to a person skilled in the art that various changes can be made and equivalents can be used as a substitute without departing from the scope of the invention. In addition, many modifications can be carried out without departing from the associated scope. Consequently, the invention should not be limited to the embodiments disclosed but rather the invention should include all embodiments falling within the scope of the appended claims. In particular, the invention also claims protection for the subject matter and the features of the dependent claims regardless of the claims referred to.