EP4092688A1 - Electrical conduit and method for manufacturing an electrical conduit - Google Patents

Abstract

A flexible electric line is proposed, which includes a flexible hose, at the ends of which are arranged electrical contact pieces and which is filled with an electrically conductive fluid that establishes an electrical connection between the contact pieces. Metal powder, for example made of copper, aluminum and their alloys, is particularly suitable as the electrically conductive fluid. Furthermore, a method and a system for producing such a line are proposed.

Description

Area

The invention relates to an electrical line, in particular a flexible electrical line. Furthermore, the invention relates to a method for producing an electrical line according to the invention and a system for carrying out the method.

background

Aluminum conductors are increasingly being used as a replacement for copper conductors, particularly for reasons of weight and cost. The main areas of use for such conductors are, for example, automotive and aircraft technology. The lower electrical conductivity of aluminum compared to copper is irrelevant for most applications. However, aluminum conductors are much more difficult to contact than copper conductors, for example, because aluminum conductors are surrounded by an oxide layer that is a very poor electrical conductor. Aluminum cables are used, for example, as busbars or stranded conductors.

A conductor rail has a solid aluminum conductor, with which the contacting problem mentioned can be mastered comparatively easily. For example, the disturbing oxide layer can be avoided by a galvanic coating of copper at the contact points of the busbar. However, busbars have the disadvantage that they are essentially rigid structures that are not suitable for every installation situation, particularly in vehicle construction, where installation space is generally very limited. Another major limitation is that busbars cannot be used to connect components or assemblies that move relative to each other. For example, a connection with a conductor rail to a wheel hub motor of an electric vehicle is not conceivable.

In applications where no busbar can be used, mechanically flexible stranded conductors are often used, which consist of a large number of individual wires. Electrical lines with such a conductor, which is expediently surrounded by a jacket made of insulating material, are often used in the automotive sector. To such lines in production In order to be able to install them effectively and quickly, the ends of the cables are provided with electrical contact parts, which are also referred to as "terminals".

With such stranded conductors, the contact problem described above is particularly pronounced due to the poorly conducting aluminum oxide layer, because each of the individual wires forming the stranded conductor is surrounded by an oxide layer, which cannot be avoided without special treatment of the stranded conductor. This problem has been known for a long time.

In order to achieve a low contact resistance between the individual wires of the stranded cable and the contact piece on the one hand and good transverse conductivity between the individual wires of the stranded conductor on the other, special crimping or welding processes are used in practice, in which the oxide layers surrounding the individual conductors are broken up or removed in some other way will. Usually a crimp or welding sleeve is first connected to the stranded conductor and then a contact piece required for the respective application is welded on. Another limitation is that crimping processes are not suitable for thick aluminum conductors because the oxide layer of the individual conductors inside can no longer be destroyed, resulting in poor transverse conductivity. In addition, thick aluminum stranded conductors settle over time, i.e. they evade the pressure of the crimp sleeve, which affects the contact quality.

From the EP 2 735 397 A1 For example, a method is known in which a pot-shaped contact piece is pushed onto a stranded conductor. Depending on the application, the contact piece is equipped with different connection elements. The contact piece is produced as a one-piece component by deep-drawing and is bonded to the conductor by friction stir welding.

What the known methods for connecting a flexible aluminum line to a contact piece have in common is that they are complex.

Proceeding from this, the present invention has the object of creating an electrical line in order to overcome or at least improve one or more of the problems mentioned at the outset.

Description of the invention

In order to solve this problem, the invention proposes, according to a first aspect, an electrical line which comprises a flexible hose, at the ends of which electrical contact pieces are arranged and which is filled with an electrically conductive fluid which establishes an electrical connection between the contact pieces.

In the context of the present invention, the term "fluid" designates a gaseous, liquid or powdered solid material. These materials have the property that a tube filled with them remains flexible transversely to its longitudinal extension and thus represents a flexible, elongate structure.

Metal powder, for example made of copper, aluminum and their alloys, is particularly suitable as the electrically conductive fluid. Mixtures of powder from different materials can also be realized for certain applications. In addition to metal powder, non-metallic materials that have high electrical conductivity, such as graphene, can also be used.

An advantage of the line according to the invention is that it is flexible, without causing the problems with regard to the contacting of the conductor that are known, for example, from aluminum stranded conductors.

In a particularly preferred embodiment, the electrically conductive fluid in the flexible hose is under an overpressure. The overpressure ensures that there is good electrical contact between the particles of an electrically conductive powder and between the particles and contact pieces of the cable. In particular, the electrical contact produced in this way is not impaired by oxide layers or the like.

In further embodiments, the electrically conductive fluid is a gaseous or liquid material. In the case of gaseous or liquid fluids, excess pressure can have a beneficial effect on electrical conductivity.

In an expedient exemplary embodiment, the hose is designed to be pressure-resistant as a high-pressure hose and withstands pressures in the range from 10 to 1000 bar, in particular pressures in the range from 100 to 600 bar. Such hoses are used, for example, in construction machines and are commercially available. This circumstance has a favorable effect on the production costs of the line.

The hose is expediently closed with closure parts which enclose the electrically conductive fluid in the hose. A gas-tight and pressure-resistant closure of the hose is of great importance in order to guarantee the electrical properties of the cable over a longer service life.

The closure parts advantageously compress the electrically conductive fluid in the tube in order to generate an overpressure. If the locking parts take on several functional tasks at the same time, it simplifies the structure of the line.

• Ablängen eines hydraulischen Schlauches auf eine für die elektrische Leitung gewünschte Länge;
• einseitiges Verschließen eines ersten Endes des Schlauches mit einem ersten Verschlussteil;
• Befüllen des Schlauches mit einem elektrisch leitenden Fluid; und
• Verschließen des Schlauches an seinem zweiten Ende.

According to a second aspect of the invention, a method for producing an electrical line according to the first aspect of the invention is proposed. The procedure has the following steps:

• Cutting a hydraulic hose to a length desired for the electric line;
• capping a first end of the tube at one end with a first cap;
• filling the tube with an electrically conductive fluid; and
• sealing the tube at its second end.

Conveniently, the electrically conductive fluid can be compressed in the tube.

In an advantageous development of the method, the electrically conductive powder is compacted after the tube has been filled with an electrically conductive powder and before the tube is closed at its second end. Compaction can be achieved, for example, by mechanically vibrating the tube to compact the powder enclosed in the tube.

It has proven particularly advantageous if the hose is filled in an inert gas atmosphere. The protective gas atmosphere prevents oxidation of the electrically conductive fluid used, which has an unfavorable effect on the electrical conductivity.

• Befüllen des Schlauches mit einem elektrisch leitenden Fluid; und
• Verschließen des Schlauches an seinem zweiten Ende;

innerhalb der Kammer ausgeführt werden.Finally, according to a third aspect of the invention, a plant for producing an electrical line according to the first aspect of the invention using the method according to the second aspect of the invention is proposed. The plant comprises a chamber with a protective gas atmosphere, with at least the steps of the method

• filling the tube with an electrically conductive fluid; and
• capping the tube at its second end;

performed inside the chamber.

Brief description of the drawing

Fig. 1

eine schematische Darstellung einer erfindungsgemäßen Leitung;

Fig. 2A

ein Ende der Leitung aus Figur 1 in größerer Einzelheit;

Fig. 2B

ein Gewindebolzen mit einem angeforderten Kontaktstück;

Fig. 2C

das Ende der Leitung aus Figur 2A mit eingeschraubtem Gewindebolzen;

Fig. 3

ein schematisches Flussdiagramm eines Herstellungsverfahrens für eine Leitung nach Figur 1; und

Fig. 4

eine Anlage zur Herstellung einer erfindungsgemäßen Leitung.

The invention is explained in more detail below by way of example using an embodiment with reference to the accompanying figures. All figures are purely schematic and not to scale. Show it:

1

a schematic representation of a line according to the invention;

Figure 2A

one end of the line figure 1 in greater detail;

Figure 2B

a threaded bolt with a required contact piece;

Figure 2C

the end of the line Figure 2A with screwed-in threaded bolt;

3

a schematic flow diagram of a manufacturing method for a line figure 1 ; and

4

a plant for the production of a line according to the invention.

Identical or similar elements are provided with the same or similar reference symbols in the figures.

example

figure 1 shows an exemplary embodiment of an electrical line 100 according to the invention. The line 100 has an electrically conductive powder 220 ( Figure 2C ) filled pressure-resistant high-pressure hose 101. The ends 102,103 of the high-pressure hose 101 are closed with contact pieces 104,105. By means of the contact pieces 104, 105, the line 100 can be connected to corresponding connections (not shown) of electrical units such as a generator or motor and a battery. The electrically conductive powder is under pressure in the high-pressure hose 101 and is compressed in such a way that the powder forms a conductor with a diameter of, for example, 5-20 mm in transverse direction is flexible, ie bendable. The electrical properties of the conductor in the high-pressure hose 101, particularly its transverse conductivity, are comparable to a solid conductor made of the same material as the electrically conductive powder. On the other hand, the mechanical properties of the line 100, in particular its bending flexibility, generally correspond to a stranded conductor with wires made of copper or aluminum. However, it must be taken into account that in the case of the line 100 according to the invention, the mechanical properties, in particular the tensile strength, are essentially determined by the high-pressure hose 101, which represents a sheathing of the electrical conductor. In contrast to this, the tensile strength of a stranded line is determined by the conductor wires or individual lines of the stranded line. This means that in the case of a stranded cable, the mechanical properties are essentially determined by the electrical conductor or conductors.

The construction of the line is described in more detail below.

In Figure 2A the end 102 of the high-pressure hose 101 is shown in a cross-sectional view. The high-pressure hose 101 has an inner layer 201 made of oil- and water-resistant synthetic rubber (nitrile rubber, NBR), which is surrounded by an insert 202 made of high-strength steel wire mesh. The insert 202 reinforces the high-pressure hose 101 in order to make it resistant to internal pressure and external mechanical stress. Surrounding the liner 202 is an outer layer 203 made of an abrasion, oil, ozone and weather resistant rubber.

A cylindrical nipple 204 is inserted into the end 102 of the high-pressure hose 101 . In the assembly position, the nipple 204 is inserted so far into the high-pressure hose 101 that a small gap S1 remains between a peripheral projection 206 formed on the nipple and the front end of the high-pressure hose 101 . Outside of the high-pressure hose 101, the nipple 204 has a section 207 whose outside diameter is larger than the section of the nipple 204 that is inserted into the high-pressure hose. An annular groove 208 is cut into the section 207, into which a retaining ring 209 with a protruding internal lug 211 is inserted. The section 207 is spaced from the peripheral projection 206 so that a gap S2 is formed which forms a groove 212 . A cylindrical Press mount 213 encloses the nipple 204 and the high-pressure hose 101. Two circumferential webs 214, 215 lying on the inside of the press mount 213 overlap the projection 206 of the nipple 204 and create a positive connection between the press mount 213 and the nipple 204. Furthermore, the press fitting 213 has internal ribs 217 which are pressed into the outer layer 203 and the insert 202 of the high-pressure hose 101 and produce a non-positive and positive connection between the press fitting 213 and the high-pressure hose 101 . Overall, the press fitting 213 ensures a mechanically stable and pressure-resistant connection between the high-pressure hose 101 and the nipple 204. The nipple 204 has a through hole 218 which is provided with an internal thread 219. In Figure 2A is the electrically conductive powder 220 ( Figure 2C ) omitted for clarity.

Figure 2B shows a threaded bolt 221 with an external thread 222. At one end of the threaded bolt 221, a contact shoe 223 is formed. The contact shoe 223 is an example of any contact piece adapted to the respective application. The threaded bolt 221 is used to close the high-pressure hose 101 at its ends 102,103. The threaded bolt 221 combines a closure part, which closes the hose 101, and a contact piece. The contact shoe 223 forms the contact piece. In other embodiments, other locking parts are used, such as plain bolts that are pressed into the nipple 204 with a swivel nut or the like. In further exemplary embodiments, closure parts are provided which provide a mechanical connection in order to be connected to different contact pieces. The mechanical connection between the closure part and the contact piece can be established, for example, via a screw connection.

Figure 2C shows the end 102 of the high-pressure hose 101 with a threaded bolt 221 screwed in.

Before the second threaded bolt 221 is screwed into the nipple 204 at the second end 103 of the line 100, the high-pressure hose 101 is filled with an electrically conductive powder. The electrically conductive powder 220 is, for example, powdered metal, in particular copper or aluminum and their alloys, and forms the electrically conductive fluid.

The filling process of the high-pressure hose 101 preferably takes place under an oxygen-free protective gas atmosphere in order to avoid surface oxidation of the grains of the electrically conductive powder 220, in particular the metal powder. The metal powder is therefore only removed from storage containers for the filling process under an inert gas atmosphere. This procedure is particularly necessary for aluminum and aluminum alloys for the reasons mentioned above. In Figure 2C the electrically conductive powder 220 is shown schematically. In reality, the grains of the electrically conductive powder 220 are close to each other so that electrically conductive contacts are formed between the grains of the electrically conductive powder 220 . In an exemplary embodiment of the electrical line 100 that is not shown, the threaded bolt 221 protrudes beyond the section of the nipple 204 that is inserted into the high-pressure hose 101 and into the high-pressure hose 101 .

figure 3 shows a schematic flow diagram for a method for producing the electrical line. In a first step S1, a hydraulic high-pressure hose is cut to a length desired for the electrical line 100. In step S2, a first end of the high-pressure hose is closed with a first closure part.

Then, in a step S3, the high-pressure hose is filled with an electrically conductive fluid. When using powdered electrically conductive material, it has proven to be advantageous if, after filling, the high-pressure hose 101 is made to vibrate in a step S4 before the hose 101 is closed with the second closure part. The powder settles as a result of the vibration and the set pressure with which the powder is compressed does not change during the service life of the electrical line 100 or only to an extent that does not impair the function of the electrical line 100 . Step S4 is not necessary when using a liquid or gaseous fluid and is therefore an optional step in the manufacturing process. Step S4 is in figure 3 therefore shown dashed.

In step S5 the hose is closed at its second end. Simultaneously with the closing of the high-pressure hose at its second end, the electrically conductive fluid located in the high-pressure hose is compressed in a step S6 until a desired final pressure is reached. If the closure parts already have a contact piece, the method ends at this point. at Closure parts that do not include a contact piece, the next step S7 is to attach a contact piece to the first or second closure part. Step S7 does not necessarily take place and is therefore in figure 3 also shown in dashed lines.

figure 4 FIG. 1 schematically shows a system for producing a line 100 according to the invention. In a chamber 401 which is filled with protective gas such as argon, carbon dioxide or nitrogen. A line 100 , which is still open on one side, is held in a holding device 402 . A predetermined quantity of metal powder is filled from a storage container 403 into the high-pressure hose 101 of the line 100 , which is still open at the end at the top, using a funnel 404 . The funnel 404 is so deep in the open end 103 of the hose 101 that the metal powder cannot contaminate the thread of the nipple 204 at the open end 103 of the high-pressure hose 101. A robot 405 then threads a threaded bolt 221 into the open end 102 of the hose 101 to complete the line. The robot 405 tightens the threaded bolt with a predetermined torque to create a predetermined pressure within the conduit 100 .

In one embodiment, the system is designed such that storage locations for raw material and finished lines 100 are provided within chamber 401 so that the protective gas atmosphere has to be broken as rarely as possible in order to remove raw material and finished lines 100 from chamber 401.

reference list

100

electrical line

101

high pressure hose

102,103

ends of the high-pressure hose

104,105

contact pieces

201

inner layer

202

inlay

203

outer layer

204

nipple

206

Circumferential projection

207

section of the nipple

208

ring groove

209

locking ring

211

Nose

212

groove

213

press version

214,215

webs

217

ribs

218

through holes

219

inner thread

221

threaded bolt

222

external thread

223

contact shoe

224

locking part

401

chamber

402

holding device

403

reservoir

404

funnel

405

robot

Claims (13)

Electrical line comprising a flexible tube (101) having electrical contacts (221) arranged at the ends and filled with an electrically conductive fluid (220) which establishes an electrical connection between the contacts (221). Electrical line according to Claim 1, characterized in that the electrically conductive fluid (220) in the flexible hose (101) is under overpressure. Electrical line according to Claim 1 or 2, characterized in that the electrically conductive fluid (220) is an electrically conductive powder, in particular a metal powder or a mixture of different powdered materials. Electrical line according to one of the preceding claims, characterized in that the electrically conductive fluid (220) comprises gaseous, liquid and/or solid material. Electrical line according to one of the preceding claims, characterized in that the hose (101) is designed to be pressure-resistant as a high-pressure hose and can withstand pressures in the range from 10 to 1000 bar, in particular pressures in the range from 100 to 600 bar. Electric line according to one of the preceding claims, characterized in that the hose is closed with closure parts (221) which enclose the electrically conductive fluid in the hose (101). Electric line according to one of the preceding claims, characterized in that the closure parts (221) compress the electrically conductive fluid in the hose. Method for manufacturing an electrical line according to one of the preceding claims, the method comprising the following steps: - Cutting a hydraulic hose (101) to a desired length for the electrical line (100); - one-sided closure of a first end (102) of the hose with a first closure part (221); - Filling the tube with an electrically conductive fluid; - Closing the tube at its second end (103). ; and Method according to Claim 8, characterized in that after the hose has been closed at its second end (103), the electrically conductive fluid in the hose is compressed. Method according to Claim 8 or 9, characterized in that after the tube (101) has been filled with an electrical powder and before the tube is closed at its second end (103), the electrically conductive powder is compacted. Method according to one of the preceding claims, characterized in that a contact piece is attached to the first or second closure part (221). Method according to one of the preceding claims, characterized in that the hose (101) is filled in an inert gas atmosphere. Installation for the production of an electrical line according to Claim 1 using the method according to Claim 8, characterized in that the installation comprises a chamber (401) with an inert gas atmosphere, at least the steps of the method - Filling the tube with an electrically conductive fluid; and - sealing the tube at its second end; be carried out within the chamber (401).

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