Copper busbar for a contact system

Abstract

A copper busbar has at least one stepped hole for fastening a cable shoe vi a screw connection. The stepped hole extends from a first surface of the copper busbar to a second surface of the copper busbar. The stepped hole has at least a first region, a second region and a third region, wherein the first region of the stepped hole adjoins the first surface, with a radius of the stepped hole being constant over the length of the second region with the second radius value. The third region adjoins the second surface, wherein the third region has at least at the second surface a radius with a third radius value which is less than the second radius value.

Claims

1. A busbar, comprising: first and second surfaces; and a stepped hole extending from the first surface to the second surface and configured to include first, second and third regions, with the first region adjoining the first surface and configured for enabling a self-clinching nut to be pressed centrally into the stepped hole in such a way that a radius in the first region assumes a first radius value and a step is formed between the first and second regions, and enabling the self-clinching nut to fasten a cable shoe to the second surface via a screw insertable into the stepped hole from a side of the second surface, said stepped hole defined by a radius which is constant over a length of the second region and defined by a second radius value which is less than the first radius value, said third region ending at the second surface and having at least at the second surface a radius defined by a third radius value which is less than the second radius value, wherein a radius at a boundary from the first region to the second region has a jump from the first radius value to the second radius value to thereby form a seating surface in parallel relation to the first surface at the boundary between the first and second regions for engagement by a toothing of the self-clinching nut, wherein the busbar is made of copper, wherein the second region adjoins the third region, and further comprising in the third region a cone extending completely across the third region and having the second radius value at a boundary to the second region.

2. The copper busbar of claim 1, wherein the copper busbar has a thickness in a range of 4 mm to 6 mm, said third region having a length of at least 2 mm, with the third radius value having a value in a range between 2.15 mm and 2.4 mm.

3. The copper busbar of claim 1, wherein the copper busbar has a recess and a thickness which is reduced in a vicinity of the recess sufficient to enable the self-clinching nut to be located completely in the stepped hole and the recess.

4. A method for producing a copper busbar as set forth in claim 1, said method comprising incorporating the stepped hole of the copper busbar into the copper busbar by a punching machine.

5. A contact system, comprising: a cable shoe; a screw connection comprising a self-clinching nut and a screw; and a copper busbar comprising first and second surfaces, and a stepped hole extending from the first surface to the second surface and configured to include first, second and third regions, with the first region adjoining the first surface and configured for enabling the self-clinching nut to be pressed centrally into the stepped hole in such a way that a radius in the first region assumes a first radius value and a step is formed between the first and second regions, and enabling the self-clinching nut to fasten the cable shoe to the second surface via the screw as the screw is inserted into the stepped hole from a side of the second surface, said stepped hole defined by a radius which is constant over a length of the second region and defined by a second radius value which is less than the first radius value, said third region ending at the second surface and having at least at the second surface a radius defined by a third radius value which is less than the second radius value, wherein a radius at a boundary from the first region to the second region has a jump from the first radius value to the second radius value to thereby form a seating surface in parallel relation to the first surface at the boundary between the first and second regions for engagement by a toothing of the self-clinching nut, wherein the second region adjoins the third region, and further comprising in the third region a cone extending completely across the third region and having the second radius value at a boundary to the second region.

6. The contact system of claim 5, wherein the copper bulbar has a recess and a thickness which is reduced in a vicinity of the recess sufficient to enable the self-clinching nut to be located completely in the stepped hole and the recess.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) The invention is described and explained in more detail below with reference to the exemplary embodiments illustrated in the figures, in which:

(2) FIG. 1 shows a copper busbar having a stepped hole,

(3) FIG. 2 shows a contact system having a fastened cable shoe, and

(4) FIG. 3 shows a contact system having a recess.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(5) FIG. 1 shows a section of a copper busbar 1 having a stepped hole 2. In this case the copper busbar 1 may have one or more stepped holes 2. The contour of the stepped hole 2 is indicated in the figure by a thicker line weight. The copper busbar 1 comprises a first surface 11 and a second surface 12. Normally, the first surface 11 and the second surface 12 run parallel to one another. The distance between the two surfaces 11,12 is the thickness d of the copper busbar 1. The stepped hole 2 extends through the interior of the copper busbar 1 from the first surface 11 to the second surface 12. In order to produce a connection to a cable shoe 3 (not shown here), a self-clinching nut 41, also known as a press-in nut, is introduced into the stepped hole 2 from the side of the first surface 11. The self-clinching nut 41 bears with its toothing, which is incorporated on its collar, on a seating surface 24. The seating surface 24 is realized in the transition from the first region 21 to the second region 22 by a step change in the value of the radius r from a first radius value r.sub.1 to a second radius value r.sub.2. In the second region 22, it is advantageous if the radius assumes a constant value over the entire length of the second region 22 in order to guide the self-clinching nut 41 in this second region 22 during its insertion and center the same in the copper busbar 1. The first radius value is formed in the first region 21 with the introduction of the self-clinching nut 41. Before the latter is introduced, the radius value in the first region may have a different value, for example the second radius value r.sub.2. An advantageous choice of the third radius value r.sub.3 is described in more detail with reference to FIG. 2. In this exemplary embodiment, the radii are constant in each case over the individual regions 21,22,23. This is not absolutely necessary, but permits a particularly favorable fabrication by punching, since in this case only simple standard tools are required on the punching machine. It is particularly advantageous in this process to provide the same radius value in the first and second region 21,22 during the punching of the stepped hole, and to provide a third radius value in the third region 23, which radius is smaller than the second radius value r.sub.2. The larger radius in the first region 21 having the first radius value r.sub.1 is then produced when the self-clinching nut 41 is introduced.

(6) In order to simplify the introduction of the self-clinching nut 41 during assembly, a greater radius than the second radius value r.sub.2 can also be provided already in the first region during the production of the stepped hole.

(7) It is furthermore possible to embody the third region in its entirety, as shown in FIG. 1, or at least in sections, as a cone. The cone forms a transition from the radius having the second radius value r.sub.2 at the boundary between the second region 22 and the third radius value r.sub.3. The third radius value is in this case reached at the surface 12, for example, or in the interior of the copper bulbar so that a cylinder-shaped section also follows on between cone and surface 12.

(8) FIG. 2 shows the copper busbar 1 having a screw connection 4 introduced into the stepped hole 2. Copper busbar 1 and screw connection 4 in combination with the cable shoe 3 constitute a contact system 30. In order to avoid repetitions, reference is made to the description relating to FIG. 1 and the reference signs introduced there. In this exemplary embodiment, the screw connection 4 shown here comprises the self-clinching nut 41, a screw 42, the cable shoe 3, a washer 43 and a spring lock washer 44. The cable shoe is reliably fastened to the second surface 12 of the copper busbar by means of said screw connection 4. However, other systems comprising clamping washer pairs, for example, or having a single washer and mechanical/chemical screw locking device in the self-clinching nut thread are also possible. Even simple screw joints without washer components, or with a single washer without additional locking device, are possible. These are possible in particular when the requirements imposed by the environmental conditions, for example due to vibrations, allow such a connection.

(9) The third radius value r.sub.3 is in this case advantageously chosen such that the screw 42 can be introduced into the stepped hole 2 from the second surface 12 without application of force, in particular without touching the copper wall. The smaller the radius value r.sub.3, the less likely is the danger that the cable shoe 3 will be bent or deformed due to the clamping pressure of the screw connection 4 when butting against parts of the second surface 12. The radius in the third region is therefore chosen as small as possible, in particular small in relation to the third radius value r.sub.3, so that the screw 42 can just about still be inserted through the third region 23. A constant radius over the entire third region 23 has the advantage that the copper busbar 1 then has a high degree of stability and strength in the vicinity of the cable shoe 3. In this way a contact with the cable shoe 3 is established over the entire surface area of the cable shoe, at least over a major part of the surface area of the cable shoe 3, with the result that high current intensities are also possible in addition to the high degree of stability of the connection.

(10) FIG. 3 shows an exemplary embodiment of a contact system 30, wherein the copper busbar 1 has a recess 50. This recess 50 is embodied in such a way that the self-clinching nut 41 does not project out from the first surface 11 at which the copper busbar 1 has a thickness d. At the recess 50 itself, the first surface is offset inwardly, such that at this point the copper busbar has only a reduced thickness d* and the self-clinching nut 41 is located completely in the recess 50 and the stepped hole 2. It is furthermore particularly advantageous if the screw 42 also does not project out from the recess, since this can help avoid injuries for example when working on/maintaining the copper busbar 1. In order to avoid repetitions, reference is made to the description relating to FIGS. 1 and 2 as well as to the reference signs introduced there.

(11) To sum up, the invention relates to a copper busbar. In order to improve the latter's ability to connect with a cable shoe, it is proposed that the copper busbar has at least one stepped hole for fastening a cable shoe by means of a screw connection, wherein the stepped hole extends from a first surface of the copper busbar to a second surface of the copper busbar, wherein the stepped hole has at least a first region, a second region and a third region, wherein the first region of the stepped hole adjoins the first surface, wherein the radius of the stepped hole is constant over the length of the second region having the second radius value, wherein the third region adjoins the second surface, wherein the third region has, at least at the second surface, a radius having a third radius value, wherein the third radius value is less than the second radius value. The invention also relates to a contact system having such a copper busbar, as well as to a converter having such a copper busbar or such a contact system. The invention further relates to a method for producing such a copper busbar.