The invention relates to a cable having at least two electrical conductors according to patent claim 1 and a method for producing a cable having at least two electrical conductors according to patent claim 10.

Electrical cables which have a plurality of conductors are known in the prior art. In this instance, the conductors are wound around each other and surrounded by an electrically insulating cable sheath. There is the risk that, owing to surface reactions, an insulating layer is formed between the conductors and the conductivity between the individual conductors is reduced.

DE 103 58 686 A1 discloses a cable having two electric conductors which are directly in abutment with each other, wherein the two conductors are surrounded by an electrically insulating cable sheet.

JP 08321332 A discloses a method of joining electric wires. Metallic powder consisting of tin, lead or solder softer than soft copper and metallic powder of any one of copper, nickel, tungsten, and molybdenum being hard conductive powder harder than soft copper are applied on the pressure bonding part of a cable in advance, before pressure bonding the pressure bonding part of the cable consisting of a plurality of element wires consisting of soft copper by means of a crimp-style terminal. By the application of the metallic powder harder than the element wire material, the metallic powder bites in the element wire at the time of pressure bonding, and the polluted film on the surface of the cable is broken, so stable polluted film removal effect and excellent performance reproducibility at mass production can be obtained.

An object of the invention is to provide an improved cable and an improved method for producing a cable.

The object is achieved by the cable according to patent claim 1. Other advantageous embodiments of the invention are set out in the dependent claims.

An advantage of the cable is that electrically conductive particles are arranged between the individual conductors of the cable. Consequently, owing to the particles, an electrically conductive transverse connection is produced between the conductors. In this instance, oxidation layers may in particular be interrupted by the conductive particles. The electrical conductivity in a transverse direction between the conductors is further improved.

In an embodiment, the conductors have aluminium or comprise in particular aluminium. In particular with aluminium conductors, it is advantageous to improve the electrical conductivity in the transverse direction. In particular with conductors of aluminium, there may be formed on the surface of the conductors oxidation layers which impair conductivity in the transverse direction.

In another embodiment, the conductors are wound around each other. During the winding operation of the conductors, a transverse force is thereby applied to the particles, which are located between the conductors. The particles are thereby pressed into the surface of the conductors. Consequently, a non-positive and/or positive-locking mechanical connection and electrically conductive connection is produced between the particles and the conductors. Consequently, it is possible for the electrical conductivity in the transverse direction between the conductors also not to be made more difficult by subsequent formation of an oxidation layer.

In another embodiment, the electrically conductive particles are constructed with sharp edges. In particular the particles are constructed in the form of a mechanically crushed powder. Owing to the sharp-edged formation of the particles, it is ensured that the particles are embedded in the surface of the conductors and consequently produce a good electrically conductive connection between the conductors in the transverse direction. The conductivity in the transverse direction also cannot be interrupted by subsequent oxidation of the surfaces of the conductors.

Depending on the selected embodiment, the particles have a size in the range between 1 µm and 100 µm. For example, the particles may have a size in the range between 10 µm and 60 µm. Owing to these orders of magnitude of the particles, on the one hand, good electrical conductivity is achieved in the transverse direction of the conductors. In addition, the arrangement of the conductors beside each other is not impaired by the presence of the particles. In particular, the conductors can be wound around each other without the particles which are arranged between the conductors disrupting the winding operation. Furthermore, owing to this size of the particles, no larger hollow spaces or free spaces are formed between the conductors.

The electrically conductive particles may, for example, have a metal as an electrically conductive material, in particular, for example, copper or a copper alloy. Copper or a copper alloy is particularly suitable for increasing the electrical conductivity in the transverse direction for electrical conductors, in particular for electrical conductors of aluminium.

In another embodiment, the particles may have a material of a ternary compound of copper and zinc with at least one other element from the following group: tin, aluminium, iron, nickel, gold, titanium, magnesium or chromium. In another embodiment, the particles have brass, the zinc content being able to be in particular between 10% and 70%.

A production of the cable described is achieved in a simple manner by the electrically conductive particles being introduced between the conductors and the electrically insulating cable sheath subsequently being applied around the conductors.

Depending on the embodiment selected, the at least two conductors may be wound around each other before the cable sheath is constructed, that is to say, are constructed in the form of a strand. Furthermore, the individual conductors may also already comprise wound conductor wires.

Another advantage of the cable described is that a crimp element can be crimped in a simple manner with a good electrical contact to conductors of the cable from which the cable sheath has been removed. Owing to the presence of the electrically conductive particles already in the cable, it is not necessary to additionally provide electrically conductive particles during the crimping operation. As a result, the crimping process is simplified per se. A good electrically conductive contact between the crimp element and the conductors is further ensured.

Depending on the embodiment selected, the electrically conducive particles can be applied to the conductors in the form of a powder, or with a carrier agent in which the electrical particles are mixed. Suitable carrier agents include, for example, organic solvents, in particular petroleum, alcohol, acetone, oils, but also fats. For example, the electrically conductive particles may be applied to the conductors in the form of a paste.

The invention is explained in greater detail with reference to the Figures, in which:

• Figure 1 is a schematic illustration of a cross-section through a cable,
• Figure 2 is a schematic illustration of a cross-section through a cable in the longitudinal direction, and
• Figure 3 is a schematic illustration of a crimp element which is crimped to conductors of a cable.

Figure 1 is a schematic illustration of a cable 1 which has two electrical conductors 3, 4. Electrically conductive particles 5 are arranged between the conductors 3, 4. The electrical conductors 3, 4 are in abutment with each other, the electrical particles 5 being clamped between the conductors 3, 4 and being connected to the conductors in a non-positive and/or positive-locking manner. Depending on the embodiment selected, the electrically conductive particles 5 are partially pressed into the surfaces of the electrical conductors 3, 4. In this manner, an improved electrical conductivity between the respective conductor 3, 4 and the electrically conductive particles is achieved. The conductors and the particles are surrounded by a cable sheath 2, which is produced from an electrically insulating material. Depending on the embodiment selected, a different construction of the cable may also be selected. For example, more than two conductors 3, 4 may be provided. In addition, each conductor 3, 4 may comprise a plurality of conductor wires. In particular, the conductors 3, 4 may comprise conductor wires which are wound about themselves, so-called strands. In addition, the conductors 3, 4 may also be wound around each other.

The conductors 3, 4 may comprise an electrically conductive material, in particular a metal material. For example, the conductors 3, 4 may have aluminium or comprise aluminium.

The electrically conductive particles 5 may have an electrically conductive material, in particular have a metal. For example, the particles may also have an electrically conductive layer. In this instance, hollow particles or particles having an electrically insulating core and an electrically conductive layer can be used.

For example, a particle may have copper. In particular, a particle may have at least partially one of the following copper alloys: CuSn, CuZn_xSn_y, CuFe, CuNiSi, CuAl_xy.

Furthermore, a particle may have a ternary connection of copper and zinc having an additional element from the following group: Sn, Al, Fe, Ni, Au, Ti, Mg or Cr.

In addition, a particle may have brass or comprise brass, the zinc content preferably being between 10% and 70%.

Figure 2 is a schematic cross-section in the longitudinal direction of the cable 1, the arrangement of the particles 5 between the conductors 3, 4 being clearly visible. In addition, in the embodiment illustrated, the conductors 3, 4 are wound around each other. Preferably, each conductor 3, 4 is constructed in the form of an aluminium strand, that is to say, each conductor 3, 4 comprises a plurality of wound aluminium wires.

The electrically conductive particles preferably have a size which is in the range between 1 µm and 100 µm, in particular between 10 µm and 60 µm.

The cable 1 is produced, for example, by electrically conductive particles 5 being applied to at least a first conductor 3. The particles may be in the form of a powder, or in the form of a paste, or in the form of a binding agent which is mixed with particles. After the particles 5 have been applied to the first conductor 3, the second conductor 4 is placed on the first conductor 3. In this instance, a pressure can be applied to the first conductor. A pressure is thereby applied to the conductive particles by the conductors. Subsequently, an electrically insulating cable sheath is applied to the conductors.

Depending on the embodiment selected, the at least two conductors can be rotated, that is to say, wound, around each other before the cable sheath is constructed and a strand conductor can be produced. Owing to the winding, a close contact is produced between the conductors 3, 4 and the electrically conductive particles 5. In particular, the electrically conductive particles 5 are pressed into the surfaces of the conductors 3, 4.

The electrically conductive particles 5 preferably have sharp edges. This is achieved, for example, by the particles 5 being constructed in the form of a mechanically crushed powder. When the electrically conductive material is crushed into particles, sharp edges are formed. For example, the electrically conductive material is processed into powder from a raw material by means of a crushing operation.

Figure 3 shows a cable 1 in which the cable sheath 2 has been removed from the conductors 3, 4 at one end. In addition, a crimp element 6 has been crimped to the exposed ends of the conductors 3, 4. The crimp element 6 has, for example, a flap which has been clamped to the exposed ends of the conductors 3, 4. Owing to the presence of the electrically conductive particles 5, the electrically conductive particles 5 are also crushed between the crimp element 6, in particular the flap, and the conductors 3, 4 during the crimping operation. Consequently, owing to the presence of the electrically conductive particles 5, an improved electrical contact between the conductors 3, 4 and the crimp element 6 is enabled.

The crimp element 6 may be constructed in the form of an electrical contact or in the form of a contact connector.