DE6936266U - BRUSH HOLDER FOR ELECTRIC MACHINERY. - Google Patents

Description

Aktiengesellschaft Brown, Boveri & CIe., Baden (Switzerland)

Brush holders for electrical machines

The trend in electrical reactor and generator construction is paying off always greater «; re unit services, with the need for excitation power for these machines also increases accordingly, so that especially with large turbo-generators, excitation currents of 8000 A and more are necessary. The excitation power is usually supplied to the inductor (pole wheel) via brushes and Slip rings fed.

In connection with these high currents and also the

more high circumferential speeds there is always the problem of effective cooling, which can reliably dissipate the power transmission and friction losses that occur and reduce the temperatures occurring on the ring and brush to values u; limited to 100 ° C. In the case of large slip rings, the power losses can be up to 60 kW and more, with 95 % of these losses occurring on the brush-slip ring sliding surface.

As is well known, the slip rings require intensive cooling

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can be achieved if the slip ring is provided with axial or radial channels through which a coolant flows intensively will. With the brushes and brush holders, however, there is only one with the conventional cooling arrangements insufficient cooling effect, which has several causes. First is the bulky geometry of conventional brush holders and theirs Arrangement around the slip ring is not very favorable from an aerodynamic and cooling point of view. Furthermore can even with very favorable structural design and arrangement of these elements with the aid of air guide chicanes At best, cooling air can be supplied to the outer surfaces of the brush holder. As experience shows, however, occurs between the brush as the element in which the heat loss occurs and the brush holder box has a very considerable heat transfer resistance on, since the brush is always guided with a considerable amount of play in the holder box and this play is off known reasons can not be significantly reduced. Between the brush and the outer wall around which the cooling medium flows of the burst catcher box is therefore a Thermally insulating air cushion which, on the other hand, cannot be sucked off or blown away due to the small size of the gap can. This leads to the fact that also known brush holder arrangements with cooling fins or cooling channels attached to the brush box result in only a very limited improvement in the cooling effect.

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The purpose of the invention is now to create a brush holder with cooling channels provided in the brush holder case, in which a much better or more effective heat dissipation is achieved than with the previous brush holders. According to the invention this is achieved in that the wall of the cooling channels is partially formed by the brush itself.

Two exemplary embodiments of the invention are explained in more detail with the aid of the drawing. In Fig. 1 , a brush holder is shown schematically in longitudinal section, while Fig. 2 illustrates a plurality of brush holders attached to a support ruler in cross section.

In Fig. 1, the brush holder box 1 is provided with cooling channels 2, its brush-side wall by the brush 3 itself is formed. 4 with the pressure spring of the brush is referred to and 5 is the slip ring provided with axial channels 6. The cooling channels 2 can run axially to the brush, as in FIG Figure is shown, or be arranged to run tangentially. With this arrangement and design of the cooling channels 2 the air flowing through comes into direct contact with the brush at various points on the brush holder box 1 5, which is excellent in thermal conductivity.

In the arrangement of Fig. 2, the brushes 11 are in a known W- ise in closely-rows brush holder boxes out 12 lh on support rulers are fastened by means of screws 13.

These rulers in turn form with not-shown Collector rings the so-called brush bridge over which the current is conducted. The brush holder boxes 12 are so formed and arranged that on the one hand between these and the support rulers 14 narrow openings 15 remain free through which « Cooling air flows in from the outside and in a more or less axial direction over the slip ring from one on the slip ring shaft attached fan is extracted. In order to achieve this directed flow of cooling gas, baffles are often used 18 or similar Kühischikanen provided.

According to the invention, cooling channels 19 are still between the Brushes 11 and the brush holder boxes 12 are provided, part of the wall of these channels through the brushes themselves is formed. The cooling air is directed in a radial direction through the slip ring fan from the outside to the inside directly on the brush guided along and at high speed.

The arrangement according to FIG. 2 can also be designed structurally in such a way that the brush holder box 12 and the support rulers can be combined in one part by guiding the brushes into recesses that are carved out directly from the support rulers will.

It should be noted that the arrangement according to FIG can also be used for brush holders that are not attached to a common carrier ruler but

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Each is held for itself. Furthermore, a reversal of the radial air flow in the channels l8,19 is possible if the slip ring is formed as Lufter Drueklüfter. The necessary air flow in the anal can also be generated by separately installed external fans.

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Claims (6)

i I --6 - 53/69 YES 11 ο η% claims 1. Brush holder for electrical machines with provided in the brush holder box closed channels that the The flow of a coolant is used, characterized in that the wall of the cooling channels is partially covered by the brush itself is formed. 2. Brush holder according to claim 1, characterized in that the cooling channels run axially to the brush. J5. Brush holder according to claim 1, characterized in that the cooling channels run radially to the brush. 4. Brush holder according to claim J, characterized in that the cooling air flow through the cooling channels takes place from the outside to the inside. 5. Brush holder according to claim 2, characterized in that the cooling air flow through the cooling channels takes place from the inside to the outside. 6. The brush holder of claim 1, wherein the brush holder boxes are arranged on a support ruler, characterized in that the brush holder boxes and the cooling channels at least partly formed by recesses in the support ruler itself 53/69 are. General power of attorney BBC A 6 No. 89/69 Gen. VoUm. Dr. Ing. Heinz Kluge · "7891 Kadelburg,! M See β Aktiengesellschaft Brown, Boveri & Cie. 1.7.71