WO2014095909A1

WO2014095909A1 - Annular clamping ring providing support for busbars

Info

Publication number: WO2014095909A1
Application number: PCT/EP2013/076960
Authority: WO
Inventors: Eric HAVERKAMP
Original assignee: Eaton Industries (Netherlands) B.V.
Priority date: 2012-12-17
Filing date: 2013-12-17
Publication date: 2014-06-26
Also published as: GB2508925A; GB201222719D0; WO2014095909A8

Abstract

The invention relates to a device for supporting and clamping two bus bar plates (2) onto each other, which device comprises: supporting elements (3) for supporting the bus bar plates; spring elements (5, 6, 7, 8) arranged opposite of the support elements (3); and an annular body (4) arranged around the support elements (3) and the spring elements (5, 6, 7, 8), wherein the annular body (4) comprises cams (13) for urging the spring elements (5, 6, 7, 8) towards the support elements (3) thereby pressing the two bus bar plates together.

Description

ANNULAR CLAMPING RING PROVIDING SUPPORT FOR BUSBARS

The invention relates to a device for clamping two objects onto each other, for example for mounting busbars. Busbars used in switchgear for electrical systems are typically mounted by arranging holes in the busbars and by using bolts and nuts to secure the busbars. Arranging holes in the busbars requires an extra machining step, which contributes to higher costs. In particular, when busbars are designed to the requirements of the customer, it is not possible to standardize the manufacturing process of the busbars.

In some cases it occurs that a busbar needs to be secured at a certain location, but that the available space is insufficient at that particular location to use conventional methods for securing the busbar. In medium and high voltage systems, the busbars will be subjected to heating up and cooling down of the busbars. This results in expansion and shrink of the busbars. When such busbars are mounted with bolts and nuts, it is necessary that the bolts and nuts are pretensioned by a torque wrench. This is time consuming and there is still a possibility that over time the bolts loosen. So, with a conventional way of mounting busbars, it is necessary to perform mainte- nance at regular intervals to check the pretensioning of the bolts and nuts.

It is an object of the invention to reduce or even prevent the above mentioned disadvantages.

This object is achieved with a device for clamping, which device comprises:

- a support element for supporting one of the objects;

- a spring element arranged opposite of the support element; and

- an annular body arranged around the support element and the spring element, wherein the annular body comprises at least one cam for urging the spring element towards the support element and onto the other one of the objects. With the device according to the invention it is possible to clamp two parts together simply by rotating the annular body. By rotating the annular body, the cam will move against the spring element, which will deform by the cam and provide a spring force to the one of the objects. As the other one of the objects is supported by the support element, both objects will be pressed together.

The device according to the invention can be simply slid over the two objects to a position where the two objects need to be clamped. Because of the annular body having at least one cam, the clamping device is space efficient.

Furthermore, the spring element will compensate any expansion due to heating of the objects, which is typically the case for busbars. A preferred embodiment of the device according to the invention comprises a second spring element and wherein the annular body comprises a second cam for urging the second spring element.

By having two spring elements on opposite sides of the objects to be clamped, more play can be taken with the spring elements, while still sufficient force is exerted by the spring elements.

It is even more preferred to provide more than two spring elements along the annular body, such that the annular body is easily centered around the objects to be clamped.

Preferably, the at least one cam is arranged on the radial inner surface of the annular body. The annular body is, because of it shape, strong and able to take large radial forces. By arranging the cams on the inside of the annular body, the radial force applied by the cam to the spring element is easily taken up.

In yet another embodiment of the device according to the invention, the spring elements comprise a convex portion with a recessed part for guiding the corresponding cam and holding the cam in the clamped position of the device. When rotating the annular body, the cam will run along the convex portion or the spring element. This will ensure a substantial linear force increase, up to the moment that the cam will drop into the recessed part. The cam will be accommodated in the recessed part and ensure that the clamping device will stay in the clamped device. Without such a recess, it could occur that the annular body moves due to the expansion and shrinking of the object and finally will rotate to a position, in which the objects are no longer clamped.

In another embodiment of the device according to the invention, the radial outer surface of the annular body is provided with ridges. These ridges will provide increased grip on the annular body, such that higher clamping forces are possible.

The invention also relates to a combination of a clamping device according to the invention, a busbar and at least one pressure plate, wherein the pressure plate is arranged against the bus- bar, the device is arranged around the pressure plate and the busbar and wherein the busbar is supported by the support element and the spring element is urged by the cam against the pressure plate.

The pressure plate could for example be a mounting plate for mounting the busbar to a hous- ing. The pressure plate can also be a connection plate to connect the ends of two busbars.

In yet another embodiment of the combination according to the invention, the busbar comprises a number of strips stacked together, which strips are clamped by the clamping device. In a very preferred embodiment, the busbar comprises a number of strips, such that a busbar with a square cross section is obtained. On each side of the busbar a pressure plate is arranged. The clamping device is provided with four spring elements, one for each of the pressure plates. In yet another very preferred embodiment, a busbar comprises a number of strips stacked together such that the busbar with a square cross section is obtained. There are two such busbars, each comprising a number of strips stacked together, awaiting to be electrically connected. On each side of the two busbars, a running busbar, made of a single strip, is arranged. The running busbar runs along the gap between ends of the two busbars to at least partially cover each side of the two busbars to connect the ends of two busbars. Four such running busbars could be arranged on four sides of the two busbars for forming an electrical connection between the two busbars. Two clamping devices are provided, each arranged at one end of the running busbars for clamping the running busbars onto the two busbars.

In yet another very preferred embodiment, two running busbars, each made of a single strip, are awaiting to be electrically connected. A busbar is used to electrically connect the two running busbars, wherein the busbar comprises a number of strips stacked together such that the busbar with a square cross section is obtained. One end of each of the two running busbars is placed on the opposite ends of the busbar, such that the busbar forms an electrical connection between the two running busbars. Two clamping devices are provided, each arranged at one end of busbar, for clamping the two running busbars onto the busbar.

These and other features of the invention will be elucidated in conjunction with the accompa- nying drawings.

Figure 1 shows a perspective view of an embodiment of the clamping device of the invention. Figure 2 shows the device of figure 1 in front view in a non-clamping state.

Figure 3 shows the device of figure 1 in front view in a clamping state.

Figure 4 shows a detailed view of a spring element of the clamping device of figure 1. Figure 5 shows a perspective view of another embodiment of the clamping device of the invention.

Figure 6 shows a perspective view of yet another embodiment of the clamping device of the invention.

Figure 1 shows in perspective view of an embodiment of the clamping device 1 according to the invention. The clamping device 1 is arranged around a busbar 2 and pressure plates 3. The busbar 2 is composed out of a number of strips 2. The clamping device 1 has an annular body 4, which is provided on the outer surface with ridges to increase the grip. Four spring elements 5, 6, 7, 8 are arranged on the inside of the annular body 4 and on top of a respective pressure plate 3 (see figure 2).

Each spring element 5, 6, 7, 8 also functions as a support element for the opposite spring element 7, 8, 5, 6 respectively.

Each spring element 5, 6, 7, 8 (see figure 4) has a convex portion 9 with at the top a recess 10. Two flanges 11, 12 are arranged on both ends of the spring elements 5, 6, 7, 8 such that the spring element 5, 6, 7, 8 can be supported around a pressure plate 3.

Four cams 13, 14, 15, 16 are provided on the inside of the annular body to cooperate with the corresponding spring element 5, 6, 7, 8.

As shown in figure 2, the cams 13, 14, 15, 16 are positioned out of contact with the spring elements 5, 6, 7, 8. By rotating the annular body 4 in the shown direction, the cams 13, 14, 15, 16 will get into contact with the spring elements 5, 6, 7, 8 and register in the corresponding recesses 10 (see figure 3). This will tension the spring elements 5, 6, 7, 8 such that the objects, i.e. the busbar 2 and the pressure plates 3 are clamped together.

Figure 5 shows a perspective view of another embodiment of the clamping device of the invention. As shown in figure 5, a busbar 2 comprises a number of strips stacked together such that the busbar with a square cross section is obtained. There are two such busbars 2, each comprising a number of strips stacked together, awaiting to be electrically connected. On each side of the two busbars 2, a running busbar 3, made of a single strip, is arranged. The running busbar 3 runs along the gap between ends of the two busbars 2 to at least partially cover each side of the two busbars 2 to connect the ends of two busbars 2. Four such running busbars 3 could be arranged on four sides of the two busbars 2 for forming an electrical connection be- tween the two busbars 2. Two clamping devices 1 are provided, each arranged at one end of the running busbars 3 for clamping the running busbars 3 onto the two busbars 2.

Figure 6 shows a perspective view of yet another embodiment of the clamping device of the invention. As shown in figure 6, two running busbars 3, each made of a single strip, are awaiting to be electrically connected. A busbar 2 is used to electrically connect the two running busbars 3, wherein the busbar 2 comprises a number of strips stacked together such that the busbar 2 with a square cross section is obtained. One end of each of the two running busbars 3 is placed on the opposite ends of the busbar 2, such that the busbar 2 forms an electrical connection between the two running busbars 3. Two clamping devices are provided, each arranged at one end of busbar 2, for clamping the two running busbars 3 onto the busbar 2. For the purpose of simplicity, not all elements are shown in Figure 6. For example, another set of analogous running busbar 3, and spring element 7 which functions as a support element for opposite spring element 5 on both the clamping devices is not shown.

Claims

1. Device for clamping two objects onto each other, which device comprises:

- a support element for supporting one of the objects;

- a spring element arranged opposite of the support element; and

- an annular body arranged around the support element and the spring element, wherein the annular body comprises at least one cam for urging the spring element towards the support element and onto the other one of the objects.

2. Device according to claim 1, wherein the support element comprises a second spring element and wherein the annular body comprises a second cam for urging the second spring element.

3. Device according to claim 1 or 2, wherein the at least one cam is arranged on the radial inner surface of the annular body.

4. Device according to any of the preceding claims, wherein the spring elements comprise a convex portion with a recessed part for guiding the corresponding cam and holding the cam in the clamped position of the device.

5. Device according to claim 4, wherein the corresponding cam is guided into the recessed part upon rotation of the annular body.

6. Device according to any of the preceding claims, wherein the radial outer surface of the annular body is provided with ridges.

7. Combination of a clamping device according to any of the preceding claims, a busbar and at least one pressure plate, wherein the pressure plate is arranged against the busbar, the device is arranged around the pressure plate and the busbar and wherein the busbar is supported by the support element and the spring element is urged by the cam against the pressure plate.

8. Combination according to claim 7, wherein the busbar comprises a number of strips stacked together, which strips are clamped by the clamping device.

9. Combination according to claim 7, wherein the busbar and the at least one pressure plate is made from copper or aluminium.

10. Combination according to claim 7, wherein the busbar and the at least one pressure plate has flat surfaces.

11. Combination according to claim 8, wherein the pressure plate is arranged against four sides of the busbar.

12. Combination of a clamping device according to claims 1 to 6, at least two busbars and at least one running busbar, wherein the running busbar is arranged against the two busbars, the device is arranged around the running busbar and a busbar of the at least two busbars and wherein the busbar of the at least two busbars is supported by the running busbar and the spring element is urged by the cam against the running busbar.

13. Combination of a clamping device according to claims 1 to 6, a busbar and at least two running busbars, wherein the busbar is arranged against the two running busbars, the device is arranged around the busbar and one running busbar of the at least two running busbars and wherein one running busbar of the at least two running busbars is supported by the busbar and the spring element is urged by the cam against the running busbar.

14. Combination according to claim 12 or 13, wherein the busbar comprises a number of strips stacked together, which strips are clamped by the clamping device.

15. Combination according to claim 12 or 13, wherein the busbar and the running busbar is made from copper or aluminum.