The invention relates to an arrangement for an electrical switch element. Such arrangements often comprise a contact switch chamber and two contacts which are arranged in the contact switch chamber. Switch elements which are constructed in this manner are, for example, used in electric and hybrid motor vehicles in order to switch the high currents which occur therein. In this instance, the two contacts are electrically connected to each other by means of a movable bridging element. When the connection is separated, owing to the high currents and field strengths, an electric arc occurs between a contact and the bridging element and can burn combustible materials, in particular plastics material in the chamber, into carbon black. This carbon black accumulates in the chamber and, owing to its electrical conductivity, can lead to short-circuits and creep currents between the two contacts.

An object of the invention is to provide an arrangement for an electrical switch element in which the risk of short-circuits and the occurrence of creep currents between the contacts are reduced.

This object is achieved with an arrangement for an electrical switch element in which a wall of the contact switch chamber between the two contacts has at least one insulation slot having an opening which extends transversely relative to a connection line between the two contacts.

Owing to the slot-like configuration with a narrow opening, a pressure wave which occurs when the electric arc is separated can hardly enter the insulation slot. Furthermore, deeper regions of the insulation slot are shaded by higher regions. The carbon black which occurs thus cannot enter the deeper regions of the insulation slot. Since the insulation slot extends transversely relative to a connection line between the two contacts, the two contacts are insulated from each other by means of the insulation slot.

The solution according to the invention can be further improved with the following developments and embodiments which are each advantageous per se and which can be freely combined with each other.

The contact switch chamber may at least partially comprise plastics material. Plastics material can be more readily processed than other materials, such as, for example, ceramic material or metal. In particular, the contact switch chamber may completely comprise plastics material, with the exception of necessarily electrically conductive components, such as the contacts.

The insulation slot may at least partially have a substantially U-shaped cross-section. Such a cross-section can be readily produced, for example, using a simple injection-moulding method. It is possible to dispense with complex undercut portions. With a U-shaped cross- section, two parallel walls face each other and are connected by means of a flat or rounded base. In an alternative embodiment, the base may also extend in an oblique manner between the two parallel walls.

In order to achieve a better shading and/or insulation effect, the insulation slot may at least partially expand behind the opening. A carbon black-free face on the base and on the sides of the insulation slot may thereby be greater and consequently a higher insulation action may be achieved. However, an insulation slot which is constructed in this manner may be more difficult to produce since, for example, during an injection-moulding method, depending on the extraction direction, undercut portions may be required. In an advantageous embodiment, an arrangement according to the invention has on a base which is located in an extraction direction an insulation slot with a substantially U-shaped cross-section. At the sides located longitudinally with respect to the extraction direction, the insulation slot has a cross-section in which the insulation slot expands behind the opening.

If the insulation slot expands behind the opening, the opening of the insulation slot may form a tapered neck portion. Such a neck portion can further improve the shielding and insulation action. The neck portion may extend to a greater or lesser extent along the insulation slot before the insulation slot widens. As the length of the neck portion increases, the pressure wave can be introduced less well.

A normal direction of the opening may extend transversely, in particular perpendicularly, relative to a connection line between the two contacts. An opening which is constructed in such a manner thus does not face directly onto one of the contacts. The opening thereby provides a smaller engagement face for the pressure wave and the pressure wave or the dust can be introduced more poorly into the opening.

A normal direction of the opening may extend transversely, in particular perpendicularly, relative to a connection line between the opening and a contact. In this embodiment, the opening again provides a smaller engagement face for the pressure wave originating from the contact, whereby the pressure wave and the carbon black can be introduced less easily into the opening.

The normal direction of the opening may in particular also face away from a contact. The shielding effect is thereby even further improved. However, the normal direction often then faces towards the other contact. It is therefore advantageous in this instance for additional shielding elements, such as projections or walls, to be provided between the other contact and the opening.

In an advantageous embodiment, the at least one insulation slot extends between the two contacts along the walls around a line which connects the contacts. The two contacts can thereby be separated from each other in an effective manner. In this instance, it is particularly advantageous for an insulation slot to be fitted at each of the sides. Owing to the insulation slot at opposing sides, a good separation of the contacts from each other takes place.

A plurality of insulation slots may be provided. These may extend parallel with each other.

In an advantageous embodiment, a continuous insulation slot is provided. In particular, a continuous insulation slot may extend in an annular and/or closed manner about a connection line between the two contacts. Since a cover of the contact switch chamber may be shaded by the bridging element, it may therefore be sufficient for the insulation slot, in particular a continuous insulation slot, to extend only on the base and at the sides, on the whole therefore extending in a U-shaped manner.

In order to selectively accumulate the carbon black which is produced and thereby to keep the carbon black load in other regions low, the wall and in particular the base of the contact switch chamber may have a wide collection trough which extends transversely between the two contacts.

The collection trough may be located between a contact and an insulation slot. The insulation slot is thereby well shaded and the carbon black which is produced is carried by the pressure wave which occurs in the vicinity of the contact when the electric arc implodes into the collection trough but not into the insulation slot. In particular, the collection trough may merge into the insulation slot, for example, with a step. This makes simple production possible. An inner wall of the collection trough, which wall is located at a side of the collection trough closer to a contact, can extend around the contact. It can thereby be ensured that the collection trough performs its function, regardless of the direction in which the electric arc extends away from the contact. In order to ensure that a uniform wear always occurs and the collection trough is not covered at one location with a heap of carbon black, the collection trough may extend with uniform spacing around the contact, for example, in a circular or concentric manner. Since the electric arc moves mostly only in a specific angular range, it may be sufficient for an inner wall of the collection trough which is located at a side of the collection trough nearer the contact to extend only partially around the contact. In particular, this may be in the region between the two contacts.

In an advantageous embodiment of a collection trough, an edge of the collection trough, which edge is located at a side closer to a contact, has a chamfer or a rounded portion. In contrast to an edge having a right angle or acute angle or with sharp edges, the material on a chamfer or a rounded portion is very much more difficult for the electric arc to wear away. The occurrence of carbon black is thereby reduced. Other edges which occur in the vicinity of the electric arc may also be rounded or have a chamfer. A chamfer is advantageous since it can be more easily produced than a rounded portion.

The contact switch chamber may be subdivided into two part-chambers by means of a partition wall which protrudes from a base into the contact switch chamber, each part- chamber having an insulation slot. A separate insulation slot is thus associated with each contact. This increases the insulation effect. The part-chambers may be connected to each other. The partition wall further increases the creep path between the two contacts, whereby the two contacts are even better separated from each other. Since, above all, carbon black is deposited on the base, the partition wall protrudes from the base into the contact switch chamber. In this instance, the bridging element may extend over the partition wall. The partition wall may only be of half-height so as not to limit the movability of the bridging element. In addition, the partition wall may also protrude from the sides into the contact switch chamber. In this instance, however, a movability of the bridging element is not intended to be limited.

The insulation slots may be separated from each other by means of the partition wall. They may in particular adjoin the partition wall and/or merge into it. The production is thereby facilitated. Each of the contacts may have a contact carrier having a contact plate and a base which is widened with respect to the contact plate. The base may during production, for example, during production using an injection-moulding method, advantageously be used as a seal. A contact piece for better contacting, for example, of a metal which does not have a tendency towards welding, may be fitted to the contact plate. A contraction or a pinched portion may be provided between the base and the contact plate, that is to say that the contact is thinner at this location. The electric arc can thereby be impeded during movement down from the contact plate towards the base.

The arrangement may comprise blow magnets, which produce a magnetic field which is perpendicular relative to a contact direction and to the connection line of the two contacts. Owing to the Lorentz force, the electric arc is selectively redirected in an inward or outward direction.

The arrangement may comprise at least two blow magnets which are opposite each other with respect to a contact, the blow magnets being connected to each other in a magnetically conductive manner by means of flux-conducting metal sheets, in particular so as to close a magnetic circuit which is directed through the contact chamber. With such an arrangement, the magnetic field in the contact chamber, in particular in the vicinity of the contacts, and consequently the blowing effect, is increased.

The arrangement may comprise an electromagnetic linear drive with a yoke. In this instance, a flux-conducting metal sheet, in particular a flux-conducting metal sheet of the magnetic circuit which is directed through the contact switch chamber, may be connected to a yoke of the electromagnetic linear drive, and thereby be located in the magnetic circuit of the electromagnetic linear drive. Such an embodiment is more space-saving since components which are already present now perform a dual function.

The material of the contact switch chamber, in particular when the material is a plastics material, may contain additives. These may, for instance, be fire-retardant agents. In particular, hard gases may also be contained. They are bound in the material at low temperatures and are released by the high temperatures as occur when the electric arc is produced. The pressure in the contact switch chamber is thereby increased and the spatial expansion of the electric arc is limited. The invention is explained below with reference to advantageous embodiments and the drawings by way of example. The embodiments described are only possible configurations, in which the individual features, as described above, may, however, be combined independently of each other or omitted. Reference numerals which are the same designate objects which are the same in the different drawings.

In the drawings:

Figure 1 is a schematic perspective view of an arrangement according to the invention;

Figure 2 is a schematic longitudinal section through the arrangement according to the invention;

Figure 3 is a schematic plan view of an arrangement according to the invention;

Figure 4 is a schematic sectioned view of an arrangement according to the invention;

Figure 5 is a schematic sectioned side view through an arrangement according to the invention;

Figure 6 is a schematic perspective view of an arrangement according to the invention;

Figure 7 is a schematic side view of the arrangement from Figure 6.

Figure 1 shows an arrangement 1 for an electrical switch element. It comprises a contact switch chamber 2 and two contacts 3 which are arranged in the contact switch chamber 2. By means of a bridging element 10 which is not illustrated in Figure 1 , the two contacts 3 can be connected to each other so that current can flow. Such switching elements may be used, for example, in electric or hybrid vehicles, in order to switch high currents.

The contact switch chamber 2 shown comprises for the most part plastics material. It is an injection-moulded component. Electrically conductive elements, such as the contacts 3, are cast with the plastics material.

When the connection between the contacts 3 and the bridging element 10 is separated there is produced in the intermediate spaces an electric arc which acts on the plastics material of the contact switch chamber 2 and burns it to form carbon black. When the electric arc separates, there is produced in the contact switch chamber 2 a pressure wave which distributes the carbon black in the chamber. In order to prevent the carbon-containing carbon black from leading to an electrical connection between the two contacts 3, the base 4 and the sides 5 of the contact switch chamber 2 which each constitute a wall 27 have between the two contacts 3 two insulation slots 6 having an opening 7 which extends transversely relative to a connection line between the two contacts 3. Owing to the narrow opening 7, the pressure wave which is produced when the electric arc separates cannot be introduced into deeper regions of the insulation slot 6. Furthermore, the edges of the opening 7 shade the deeper regions so that no carbon black is accumulated in the deeper regions. In the deeper regions of the insulation slot 6, therefore, an electrical connection between the two contacts 3 which is produced by the carbon black is interrupted. Short-circuits and creep currents between the two contacts 3 are thereby prevented.

Owing to a partition wall 9, the contact switch chamber 2 is sub-divided into two part- chambers. These are connected to each other. Each of the part-chambers 8 has an insulation slot 6. The insulation slots 6 merge directly into the partition wall 9, that is to say, a wall of the insulation slot 6 at the same time forms a part of the partition wall 9.

The partition wall 9 further increases the creep path between the two contacts 3. This further increases the insulation effect. The partition wall 9 extends away from the base 4 and protrudes into the contact switch chamber 2. The partition wall 9 is only of half-height in order not to limit movability of the bridging element 10. It also does not protrude from the sides 5 into the contact switch chamber 2, also in order not to limit movability of the bridging element. Furthermore, the carbon black accumulates increasingly on the base, whereby a partition wall 9 is particularly advantageous in this instance.

The insulation slots 6 extend between the two contacts 3 along the walls, that is to say, along the base 4 and the sides 5 about a line which connects the contacts 3. The insulation slots are continuous on the base 4, at the sides 5 and therebetween. A peripheral insulation effect is thereby achieved since the substantially U-shaped path of the insulation slots 6 separates the two contacts 3 from each other. In an upward direction, no insulation slot 6 is required since there is arranged in this region the bridging element 10 which shades the region located above it.

Figure 2 is a longitudinal cross-section through the arrangement 1 of Figure 1 with a bridging element 10. In order to produce an electrical connection between the two contacts 3, the bridging element 10 is moved in the contact direction K onto the contacts 3. This can be carried out by means of a drive which is not shown here. In order to prevent welding, there are fitted to the contact plates 1 1 contact pieces 12 which comprise a material which does not have a tendency to weld. Corresponding contact counter-pieces 13 are arranged on the bridging element 10. At a lower end, the contacts 3 each have a base 14 which is constructed so as to be wider relative to the contact plate 1 1. The bases 14 may act as a seal if the arrangement 1 has been produced with an injection-moulding method. The plastics components are injected around the bases 14. As an alternative to the described production using an injection-moulding method, the contacts 3 may also be pressed in the plastics material or screwed to it. Other fixing possibilities are also conceivable.

Between the contact plate 1 1 and the widened base 14 is a contraction 22 which makes it more difficult for the electric arc to move from the contact plate 1 1 onto the base 14.

The insulation slots 6 have in the region of the base 4 a substantially U-shaped cross-section. They are thereby particularly easy to produce with an injection-moulding method, in which the contact switch chamber 2 is extracted from a corresponding mould in an extraction direction E. The insulation slots are each delimited by two inner walls 16 and a base 17. These each extend in a planar manner. In an alternative embodiment, the inner walls 16 and in particular the base may also be constructed so as not to be planar Furthermore, in particular the base 17 may not be at right angles with respect to the inner walls 16, but could, for example, extend in an oblique manner.

The arrangement 1 further has two collection troughs 18 which serve to collect the carbon black in a selective manner in this region and to keep it away in particular from the insulation slots 6. The collection troughs 18 are each arranged beside an insulation slot 6 and merge via a step 19 directly therein. The collection troughs 18 are each located between a contact 3 and an insulation slot 6. The insulation slots 6 are therefore located when viewed from the contact 3 behind the collection troughs 18 and are shaded by them. The collection troughs 18 each have at the edges which are located at a side closer to the contact a chamfer 20. This reduces the development of carbon black since a chamfer or a rounded portion is more difficult for the electric arc to burn to carbon black than a sharp corner or edge.

Figure 3 is a plan view of an arrangement 1. The collection troughs 18 each extend partially around the contacts 3. At the centre, the inner walls 21 of the collection troughs 18 which are closer to the contacts 3, extend with uniform spacing around the contacts 3. It is thereby possible for the electric arc always to have substantially the same spacing from the contact 3 when it separates.

The insulation slots 6 have in the sides 5 a different cross-section from that at the base 4. At the sides 5, the insulation slot 6 expands behind the opening 7. In this region there is therefore a hollow space which has a larger cross-section than in the region of the opening 7. The length of the inner wall is thereby increased, particularly in the regions which face away from the opening 7, and the insulation effect of the insulation slot 6 is again improved. A shading effect is also thereby improved. However, in comparison with a U-shaped embodiment of the insulation slot 6, as appears at the base 4, such an embodiment is more difficult to produce. In the example shown, however, the insulation slot 6 extends at the side 5 parallel with the extraction direction E in which the contact switch chamber 2 is extracted from the mould after the injection-moulding operation. Production is thereby simple.

The opening 7 forms a tapered neck portion 28 which can extend into the insulation slot 6 to a greater or lesser extent. As the neck portion 28 becomes longer, a pressure wave in the hollow space located therebehind can be increasingly damped.

The normal directions N of the openings 7 of the insulation slot 6 extend perpendicularly relative to a connection line between the two contacts 3. The normal directions N in the region of the sides 5 are substantially parallel with the base 4 and perpendicular relative to the contact direction K and the extraction direction E. In the region of the base 4, the normal directions N are parallel with the contact direction K and the extraction direction E. Owing to this embodiment, a collection effect by the opening 7 is minimised.

Figure 4 is a cross-section through an arrangement 1. There are arranged laterally beside the contacts 3 blow magnets 23 which face each other in pairs with respect to a contact 3. The blow magnets 23 produce a magnetic field which is applied in the region of the contacts 3 perpendicularly relative to the contact direction K in which the bridging element 10 is applied to the contacts, and extends perpendicularly relative to the connection line between the two contacts 3. The electric arc which occurs when the electrical connection is separated is moved in a selective manner by the magnetic field away from the contact piece 12 in an inward or an outward direction. In this instance, it increases and ultimately separates. Two blow magnets 23 which are arranged at a side 5 are connected to the side by means of a flux-conducting metal sheet 24.

Figure 5 shows that the blow magnets 23 are further connected to each other at the upper side by means of an additional flux-conducting metal sheet 25. The magnetic field thus forms a magnetic circuit which is directed through the contact switch chamber 2. Owing to the coupling via the flux-conducting metal sheets 24, 25, the magnetic field M within the contact switch chamber 2, in particular in the region of the contacts 3, is particularly strong and the extinguishing effect of the magnetic field M is particularly good. In order to magnetically connect the upper flux-conducting metal sheet 25 to the lateral flux- conducting metal sheets 24, it is positioned accordingly with respect to the two horizontal upper edges 26 of the flux-conducting metal sheets 24. This enables simple assembly. In order to prevent over-determination in terms of tolerances, the upper flux-conducting metal sheet 25 is positioned with a small gap dimension with respect to the horizontal upper edges 26.

Figure 6 shows an arrangement 1 which further has another yoke 30, for example, for an electromagnetic linear drive (not shown), which moves the bridging element in the contact direction K. It can further be seen that the upper flux-conducting metal sheet 25 is connected to the yoke 30 and is thereby located in the magnetic circuit of the electromagnetic linear drive for the bridging element 10. The flux-conducting metal sheet 25 is thus required for the magnetic circuit of the electromagnetic linear drive and is additionally used for the magnetic field M of the blow magnets. This embodiment is particularly space-saving since the blow magnet circuit uses the iron components of the drive system which are already present. Furthermore, the lateral flux-conducting metal sheets 24 may thereby be constructed so as to be planar.

Figure 7 is a side view of the arrangement of Figure 6. It can be seen that the upper flux- conducting metal sheet 25 is positioned with a small gap relative to a horizontal upper edge 26 of the flux-conducting metal sheet 24. However, the flux-conducting metal sheet may also be in abutment with the horizontal upper edge 26 of the flux-conducting metal sheet 24.

The materials of the contact switch chamber 2, in particular plastics materials, may contain additives. In particular, there may be incorporated in the materials hard gases which are converted into the gaseous state by the heat of the electric arc and thereby increase the pressure in the contact switch chamber 2. A spatial expansion of the electric arc is thereby limited. List of reference numerals

Arrangement

Contact switch chamber

Contacts

Base

Sides

Insulation slot

Opening

Part-chamber

Partition wall

0 Bridging element

1 1 Contact plate

12 Contact piece

13 Contact counter-piece

14 Base

16 Inner walls of the insulation slot

17 Base of the insulation slot

18 Collection trough

19 Step

0 Chamfer

1 Inner wall of the collection trough

2 Contraction

3 Blow magnets

4 Flux-conducting metal sheet

5 Flux-conducting metal sheet

6 Horizontal upper edge

27 Wall

28 Neck portion

29 Contact carrier

30 Yoke of the electromagnetic linear drive

E Extraction direction

K Contact direction

M Magnetic field

N Normal direction