Method for securing winding components in the slot of a rotary electric machine

(74) Agent

A / S Oslo Patent Office Dr. ing. K. 0. Berg, Oslo.

(56) Cited publications

No.

455'62

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of fastening winding elements in the tube of a rotary electric machine by means of a wedge and by means of deformable and curable inserts, etc. under pressure can be adapted to the shape of the spaces between the winding elements and / or between the winding element and the bottom of the groove. / or between the winding element and the wedge respectively. the surface of the wedge. The invention also relates to an intermediate method for carrying out the method of progress.

The windings for rotating electric machines are nowadays practically exclusively composed of coils or rods, whereby two insulated coil sides are usually arranged in a groove. The grooves are in turn closed by usually trapezoidal wedges of insulating material which will hold the conductors mechanically in place in the groove.

In view of the machine's operational safety, it is very important that the mechanical retention can be guaranteed over longer operating times and under all operating conditions of the machine. A wide variety of solutions are known to provide a better solution to the problems associated with the winding element retention. In CH-PS 564 872 there is disclosed a slot closure device, in which several disc springs are arranged in an axial row one after the other between the track wedge and the windings. According to German Offenlegungsschrift 21 65 727, a corrugated leaf spring is used as a biasing device. The deformation capability of these elements limits the duration of a secure attachment. CH-PS 433 494 discloses another embodiment in which a corrugated leaf spring can be further prestressed by means of pivots available outside the groove. This solution is constructively very complicated and comprehensive. German Offenlegungsschrift 15 38 975 discloses a method for fastening the winding rods in a groove, which utilizes resilient, hardening only groove inserts, which are brought to a temperature necessary for curing after insertion into the groove and after the groove is closed._Tket with a wedge. The disadvantage of this embodiment is that in this way, sufficient bias cannot be maintained. According to German Offenlegungsschrift 23 42 168, resilient hardenable track inserts are also used. They are coated with a foam material on at least one side and contain substances which act as activators respectively. accelerating on the curing reaction of the impregnation resin for the insulation. After closing the groove and connecting the winding, the insulation is insulated for the winding rods and then cured, thereby also hardening the groove inserts. This method is only applicable to the complete impregnation of a winding.

In particular, the object of the invention is to provide a method of the type mentioned in the introduction and an intermediate method for carrying out the method, which does not suffer from the disadvantages of the known devices and not only ensures adaptation of the inserts to the abutting surfaces, but. also a sufficiently large and durable bias, which is necessary for strong damping of the vibrational amplitudes and winding motions, even under extreme mechanical stresses, as they f. ex. occurs in multi-phase short circuits.

The above-mentioned problem is solved by a method of the type mentioned in the introduction, in that the inserts laid down in the groove ii and known per se, the winding elements and if necessary also the wedge support are pressurized, that the inserts are then cured by a temperature increase and the wedge is fixed in the groove. first after curing the inserts.

The advantage of the invention lies particularly in the fact that in this way a sufficiently large for 2 * voltage of more than 200 N / cm can be sustained in this way, which counteracts the trace forces.

It is convenient that the spacers are cured at a temperature increase of 1-5 ° K / h, preferably 2 ° K / h. The slow rise in temperature is particularly favorable for objects with very large heat capacities and ensures good deformation of the shims and rapid heating.

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It is advantageous that the spacers are cured at a pressure of 200 to 400 N / cm. The advantage of this method is that the deformable shims are transformed into a practically incompressible state only after parkically maximal deformation.

The spacer for carrying out the method conveniently consists of a solid strip and a deformable and curable coating on one or both sides of the strip. The thickness of the solid strip can advantageously be adjusted to the desired distance, so that the thickness of the deformable and curable coating can remain low. Coatings on both sides are advantageous when the insert is between two surfaces. tolerances to be equalized. In this case, one can of course also use two single-sided coatings, whereby the uncoated surfaces of the coatings face each other and can act as sliding surfaces.

The solid strip advantageously consists of a fiber-reinforced, resin-impregnated and cured single or multi-layer material, e.g. of polyester or epoxide resin impregnated glass fabric, glass mat, fiberglass or polyester fiberglass or combinations thereof. The deformable and curable coating of the solid strip on one or both sides may consist of single or multilayer material impregnated with B-stage artificial resin, e.g. a glass fabric, fiberglass or polyester fiberglass impregnated with B-stage polyester or epoxide resins. These materials ensure good compressive strength after curing.

In another embodiment, the height of the deformable coating is greater than one-half of the height tolerances to be offset between the abutment rafts of the groove and / or the winding elements and less than twice the height tolerances mentioned. Thereby, the deformable portion of the liner made of the coating is kept as thin as possible.

In one embodiment, the uncoated surface of a unilaterally coated solid strip is smooth and / or provided with a lubricant,

eg. with a silicone film or with fluorine wax in an organic solvent. This constructive embodiment allows for thermal expansion of the groove filling elements when required.

The spacer is suitably coated with an electrically weak conductive and elastic lacquer, e.g. a silicone or polyurethane based lacquer with graphite or soot filler. By this feature, the interlayer adheres to the surroundings, while the offset currents are safely diverted.

In the drawing, some exemplary embodiments of the subject matter of the invention are shown in simplified reproduction.

Fig. 1 shows an embodiment of an intermediate layer according to the invention with a deformable coating on both sides.

Fig. 2 shows another embodiment with two spacers coated on one side each.

Fig. 3 shows a two-conductor groove, with simplified reproduced intermediate according to the invention and with a schematically indicated auxiliary device for generating a pressure.

Fig. 4 shows the groove with groove fill elements according to fig. 3, whereby the groove after curing of the inserts is closed with a wedge.

Fig. 1 shows a solid strip 1, which is provided on both sides with deformable and curable coatings 2. The solid strip 1 consists of a multilayer glass fabric impregnated with epoxy resin and cured. · The thickness of the strip 1 is adapted to the desired spacing . The deformable coatings 2 are only 0.5 to 1 mm thick, whereby this thickness extends to equalize the usual height tolerances. The deformable coatings 2 consist of glass fibers and are impregnated with B-stage epoxy resin, i.e. in a partially cured state. The spacer according to fig. 1 is provided with a silicone lacquer with graphite filler.

FIG. 2 shows two interlays, each with a solid strip 1 ', which on one side is provided with a deformable coating 2. The solid strips 1' consist of a glass fabric impregnated with a heat-resistant epoxy resin and cured. The uncoated surfaces of the solid strips 1 'are smooth and provided with a lubricant known per se. The deformable coatings 2 consist of a fiberglass web impregnated with B-stage epoxy resin and the coating width is 0.5-1 mm.

The process according to the invention is carried out, for example, as follows: In the groove 3 in FIG. 3, an insert 11 is placed on the bottom of the groove. A lower conductor 5 is provided on the insert, which is provided with a main insulation 6. Thereafter, an intermediate layer 10 is left, whereupon an upper conductor 4 with a main insulation 6 is placed in the groove 3. On the insulation 6 of the upper conductor 4 a final insert 9 is applied. this is a wedge support 8, which extends over the entire length of the track and is designed as a metal strip. The spacers 9, 11, 11 are in FIG. 3 only indicated simplified by outline lines and may be made according to FIG. 1 or 2 or as an optional combination of said spacers. Thereafter, a pressure of 300 N / cm is exerted with a purely schematically illustrated auxiliary device 12 against the wedge support 8 in the radial direction, i.e. from top to bottom in FIG. 3 while heating the conductors 4,5 to approx. 120 ° C with heating at a temperature rise of approx. 2 ° K / hour. During this operation, the coatings 2, which are not deformable at room temperature, will reach a deformable state and gradually compress together depending on the plant conditions. Thus, a good, clear-free adjustment of all elements present in the groove is achieved and since the deformable coatings 2 on the inserts are cured after complete deformation, this condition after several hours of temperature influence will also be maintained after the temperature effect. According to this method, the wedge 7 (Fig. 4) is fixedly known in the groove 3. By means of the wedge 7, bias of up to 300 N / cm can be developed to fix the conductors 4,5, without any further substantial deformations of inserts 9, 10, 11. Thus, a high bias is ensured for a long time. Hence the use of. the same material composition of the coatings 2 possible regardless of the required height of the inserts 9, 11, 11.

The subject matter of the invention is of course not limited to that shown in the drawing. Thus, unilateral and / or two-sided coatings can be arranged layered over one another in optional combinations. They can also e.g. only used between the wedge 7 and the upper conductor 4 or between the conductors 4 and 5.