JPH0444503B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to a method of insulating the exterior of an armature coil of, for example, a rotating electrical machine, and particularly to a method of insulating the exterior of a coil that easily conforms to the outer shape of the coil and is less likely to create gaps that cause wrinkles or voids. [Technical background of the invention and its problems] Mica foil, whose base material is impregnated or coated with adhesive resin, is used as an exterior insulation material for armature coils, especially as a known insulation material used for vacuum and pressure impregnation of synthetic resins. It is pasted together. The adhesive resin in this case is
It hardens at room temperature or by heating. Therefore, the base material and the mica foil, which are bonded to each other by this adhesive resin or, as the case may be, another adhesive resin, become quite hard when used as an insulating material for winding an insulating tape or the like. Furthermore, since the elongation of mica foil is as small as 1% or less, it is difficult to wrap it completely and without voids around the coil to be insulated. In particular, in the case of armature coils, etc., insulating tape is wrapped around curved parts, excluding straight parts inserted into core slots, so that there are as few wrinkles as possible and no voids in the insulating layer. A tensile force is required and the tape ends up tearing. For this reason, it is difficult to wrap the insulating tape so that there are no wrinkles on the coil to be insulated, that is, there are no voids in the insulating layer. In order to eliminate these drawbacks even to some extent, the impregnated resin is filled not only within the insulating tape but also into the voids that occur between the tape layers in order to form complete insulation. As a method for this purpose, resin is impregnated from the outer circumferential side by applying vacuum pressure, but attempts have been made to prevent resin from flowing out under normal pressure. For example, as shown in Japanese Patent Publication No. 57-18419, a heat-shrinkable film tape is wrapped around the outer periphery, the film tape is shrunk by heating, and then fitted onto a coil. This method was successful for straight parts of the coil and coils with a large radius of curvature, but for curved parts with a small radius of curvature, such as the armature coil loop part of a DC machine, the shrinkage rate of the shrink tape alone is insufficient to prevent the shrink tape from wrinkling. It has not been possible to eliminate openings at the edges of the tape which are themselves caused by winding. Therefore, the resin in a solution state whose viscosity has been reduced by heat curing will easily flow out of the openings, and there is an extremely high possibility that voids will be included in the insulating layer. I can't do it. [Objective of the Invention] The present invention has been made in view of the above-mentioned drawbacks of the prior art, and it is an object of the present invention to provide a coil exterior insulation method that conforms to the irregularities of the coil and has no gaps that can cause wrinkles or voids even with a small tensile force. With the goal. [Summary of the Invention] In order to achieve the above object, the present invention provides adhesive resin that is difficult to penetrate under normal pressure and is applied to the surface of a base material made of aramid paper, which has high conformability and maintains flexibility at room temperature. Adhesive resin made of curable or heat-curable silicone resin is 8 to 24% of the total weight.
% and laminated with a nonwoven fabric made of flexible aramid fibers made into a strip by entangling long fibers made of synthetic resin. This is an exterior insulating method for a coil, in which the exterior insulating material is impregnated with a resin by vacuum pressure and then heated and cured. [Embodiments of the Invention] The method of the present invention will be described below. The exterior insulation material used in the method of the present invention is produced as follows. In other words, the adhesive resin is difficult to penetrate under normal pressure,
A flexible product in which a room-temperature-curing or heat-curing adhesive resin that maintains flexibility at room temperature is coated on the surface of a highly conformable base material, and long fibers made of synthetic resin are entwined with this to form a band. It is made by pasting together non-woven fabrics. In this case, it is important that the base material and the nonwoven fabric are bonded together so that they do not separate when the coil is wound, and that the adhesive does not seep into the back side of the bonded surface of the nonwoven fabric. If the amount of adhesive is excessive and the adhesive infiltrates to the back side of the nonwoven fabric bonding surface, interphase adhesion will occur between the overlapping base material and nonwoven fabric during half-overlap winding, resulting in resin impregnation. inhibit. The thus obtained exterior insulating material is wound into a coil with the exterior insulation material facing outward. When winding, the resin does not appear on the surface of the base material or nonwoven fabric, so the coefficient of friction on the surface of the exterior insulating tape is very small. Therefore, the coil can be wound without wrinkles or voids with a small tensile force. Exterior insulation can be formed. Since the base material and nonwoven fabric of the exterior insulation material have flexibility, they adapt well to the irregularities of the coil surface. In particular, nonwoven fabrics adapt well to any shape, so when combined with a base material that is difficult for resin to penetrate, a void-free insulated coil can be obtained. An embodiment of the present invention will be described below with reference to the drawings. Example FIG. 1 shows a cross-sectional view of the exterior insulation material, and the second
The figure shows a perspective view of the armature coil covered with an exterior insulating tape. In Figure 1, N410 Nomex paper (DU PONT
YR1291 silicone varnish (manufactured by Toshiba Silicone Co., Ltd.) 1 is used as a flexible adhesive, and 12% of the total weight of YR1291 silicone varnish (manufactured by Toshiba Silicone Co., Ltd.) 2 is evenly applied thereto, and aramid nonwoven fabric 3 is bonded to it, and then dried. Exterior insulation material is obtained. In FIG. 2, the exterior insulating tape 4 is wound once in a half-wound manner around the straight portion 5 and curved portion 6 of an armature coil which has been subjected to main insulation in advance. The armature coil thus obtained is impregnated with resin under vacuum and pressure, and then heat-cured. For comparison, a comparative example was prepared in which the armature coil was wound with an exterior insulating tape in which the amount of adhesive for bonding the base material and the nonwoven fabric was 2% based on the total weight was wound once around the armature coil in the same manner as in the example. A comparative example in which an exterior insulating tape with an adhesive amount of 2% of the total weight is wrapped once around the armature coil, and an exterior insulating tape with an adhesive amount of 28% of the total weight is wrapped around the armature coil. A comparative example in which the coil was wound with one half-height wrap, and a comparative example in which an exterior insulating tape with an adhesive amount of 24% of the total weight was wound once in half-height around the armature coil using the same method as above. The armature coil was manufactured by In order to compare the characteristics of each armature coil manufactured in this way, the winding properties of the exterior insulation tape,
BDV (breakdown voltage) dielectric loss tangent was measured. The results are shown in Table 1 below.

[Table] As is clear from the above results, in the Examples and Comparative Examples, there was no peeling between the tape base material and the nonwoven fabric during winding, and the dielectric loss tangent and BDV were also good. In the comparative example in which the amount of adhesive was small, the adhesion between the base material and the nonwoven fabric was insufficient, resulting in poor winding. In addition, in a comparative example in which the amount of adhesive was increased, the adhesive that had soaked into the surface of the nonwoven fabric caused interlayer adhesion between the nonwoven fabric on the upper layer of the half-wound tape and the base material on the lower layer, resulting in poor impregnation of the resin. It was happening. In addition, as another example, a polyester film is used as a base material that is difficult for adhesive resin to penetrate under normal pressure and is highly compatible, and N267 epoxy varnish (manufactured by Nitto Denko Corporation) is used as a flexible adhesive.
This was selected and applied at 24% of the total weight, and then bonded together using polyester nonwoven fabric (manufactured by Nippon Vilene Co., Ltd.), which is one of the long fibers made of synthetic resin, and dried to obtain an exterior insulation material. Example 1
As a result of investigating the characteristics of an armature coil manufactured by the same resin treatment and heat curing, results similar to those of the comparative example were obtained. The insulating layer formed by the exterior insulation method according to the present invention is cured after being impregnated with resin by vacuum or pressure.
Formed completely without voids. That is, the gas in the insulating layer is discharged through the exterior insulation under vacuum, and through the steps of injecting resin and applying pressure, the gas is uniformly permeated and dispersed from inside the insulating layer and reaches its surface. The individual insulating layers are further heat-cured together with this impregnated resin. Therefore, according to the exterior insulation method according to the embodiment of the present invention, the gas in the insulation layer is discharged to the outside through the exterior insulation by a vacuum process, and the resin is injected by pressurization and heated. Even when the resin becomes a solution with a lower viscosity during curing, it does not flow out and hardens as it is, so no voids are created. Through experiments conducted by the inventors, there is a clear difference between when only the base material of the exterior insulation material of the example is taped to the exterior of the insulation coating of the coil and when the exterior insulation material of the example is taped. This was confirmed. That is, when the two types of coils taped to the coil exterior were immersed in a resin with a viscosity of 80 centipoise at normal pressure, the taped coil with only the base material showed almost no resin intrusion, but by applying vacuum pressure, Impregnated. In addition, two types of coils impregnated with resin are heated and cured in a constant temperature bath.
When the cross section of the coil was observed, it was found that the resin filling was much more satisfactory when the insulating material was taped. From these results, it was confirmed that the resin impregnated and flowed out from the edge of the taping tape. Further, in the examples, silicone varnish is used as the adhesive resin that is flexible at room temperature, but the adhesive resin is not limited to this, and silicone-based resins may also be used, and in this case, it can be used regardless of the material of the base material. Even in this case, the same effects as in the above-mentioned embodiment can be obtained. [Effects of the Invention] As described above, according to the exterior insulation method of the present invention, the adhesive resin interposed between the base material and the nonwoven fabric is
The resin remains flexible at room temperature, and it maintains this state even when it is wound around the outer circumference of a curved part such as a coil, so the inherent flexibility of the base material and nonwoven fabric is sufficiently maintained, and the exterior The stress difference in the tensile force applied to the insulating material is well absorbed by the deformation of the flexible resin or the nonwoven fabric interposed between the two. Therefore, it conforms well to the irregularities of the coil, and in combination with the flexibility of the exterior insulation material, it is possible to obtain exterior insulation without gaps that can cause wrinkles or voids even with a small tensile force.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of an exterior insulating material used in the method of the present invention, and FIG. 2 is a perspective view showing a part of an armature coil to which the exterior insulating material is applied by the method of the present invention. 1...Base material, 2...Adhesive resin, 3...Nonwoven fabric,
4... Exterior insulation material, 5... Straight section of armature coil, 6... Curved section of armature coil.

Claims (1)

[Claims] 1. On the surface of the base material made of aramid paper, which is difficult for adhesive resin to penetrate under normal pressure and is highly compatible,
A flexible adhesive resin made of a room-temperature-curing or heat-curing silicone-based resin that maintains flexibility at room temperature is coated at 8 to 24% of the total weight, and long synthetic resin fibers are entangled with this to form a band. An exterior insulating material obtained by laminating non-woven fabrics made of aramid fibers is wound around the outer circumferential surface of a coil with the non-woven fabric facing outside, and the exterior insulating material is impregnated with resin under vacuum pressure and then heated and cured. A method for insulating the exterior of a coil.