JP5019594B2 - Insulated wire - Google Patents

Description

  The present invention relates to an insulated wire used for a motor winding.

Insulated electric wires coated with an electrical insulator are used in large quantities for applications of coils incorporated in various electric devices. It is often used particularly in electrical equipment represented by motors and transformers. In recent years, miniaturization and high performance of these devices have progressed, and there are many usages in which an insulated wire is pushed into a very narrow part. Specifically, it is not an exaggeration to say that the performance of a rotating machine such as a motor is determined by how many wires are put in the status lot. As a result, the cross-sectional area of all conductors relative to the status lot cross-sectional area is determined. The ratio (the space factor) of (the total conductor cross-sectional area of each electric wire) has become very high in recent years.
Inside the stator slots, if the insulated wire round cross-section closely packed, the failure to increase the large cross-sectional area as the space factor of the voids and or the insulating film becomes a dead space. For this reason, when coiling an insulated wire, the more the wire with a round cross-section is deformed, the more the wire is pushed into the status lot and an attempt is made to improve the space factor. Reducing the cross-sectional area of the film to a very small value was not performed because there is a risk of sacrificing its electrical performance (such as dielectric breakdown characteristics).

  On the other hand, as a means for improving the space factor, the use of an insulated electric wire having a rectangular wire whose cross-sectional shape is similar to a square shape (square or rectangular) has come to be performed. The use of flat wires can have a dramatic effect on increasing the space factor.

  Under these circumstances, attempts have been made in recent years to omit insulating paper (between phases and between core slots) for the purpose of further improving the space factor. However, when a conventional insulated wire is used, corona discharge occurs and the insulated wire is deteriorated, and it is difficult to omit the insulating paper. In particular, the electric field is concentrated on the core edge portion, which is an obstacle to omitting the insulating paper.

In order to suppress corona discharge in an insulated wire, it is conceivable to increase the coating of the insulated wire, but this reduces the space factor of the conductor with respect to the status lot. In addition, in the round wire, as an insulated wire for suppressing corona discharge, for example, an electric wire for suppressing discharge by interposing a semiconductive layer (see Patent Documents 1 and 2), and a filler in an insulating material, corona resistance is improved. An electric wire to be improved (see Patent Document 3) has been shown so far, but there has been no electric wire that can be used while maintaining the high performance of the motor in the status lot in which the insulating paper is omitted .
Also, if omit the insulating paper of the slot, scratches when inserting the winding there is a problem that occurs.
JP 2005-251573 A JP 2005-285755 A JP 2006-302835 A

  An object of the present invention is to provide an insulated wire for winding that improves the corona characteristics between a slot into which an insulated wire is inserted and / or between adjacent insulated wires, thins the coating, and is hardly damaged. .

The present invention
Wound by an insulating wire of the flat wire used to form a coil,
Insulating wires the thermoplastic resin coating layer is formed directly or indirectly on the conductor, projections on the outermost layer of the thermoplastic resin coating layer is provided,
When the projection of the coil formed by winding is used, projections have a strength enough is not lost substantially by the compressive stress experienced by the slot and / or adjacent insulated wire insulated wire is inserted ,
The top of the projection, wherein the outer shape of the lateral direction in the insulating wire, the outer shape of the cross section of the projecting the short side direction of the force of the top is convex curved shape having an arcuate radius 100~200μm there is provided a insulated wire shall be the.

  The insulated wire of the present invention can improve the corona characteristics between the slot into which the insulated wire is inserted and / or the adjacent insulated wire, and can reduce the thickness of the coating. Moreover, it is hard to be damaged. Therefore, it can be preferably used by inserting it into the status lot of the motor without insulating paper.

Hereinafter, the present invention will be described in detail with reference to the drawings.
FIG. 1 is a cross-sectional view showing a preferred embodiment of the present invention. One embodiment of the present invention includes a conductor 1 having a substantially square cross section, a thermoplastic resin coating layer 2 coated with a thermoplastic resin on the outside thereof, and at least one protrusion on each surface of the thermoplastic resin coating layer 2. 3 is an insulated wire provided.
FIG. 2 is a plan view of the insulated wire. In addition, the protrusion 3 does not necessarily need to be continuously provided on the surface of the thermoplastic resin coating layer 2 as illustrated, and may have, for example, a shape provided intermittently.

As the conductor 1 used in the present invention, a material similar to the conductor conventionally used in insulated wires can be used, but preferably, low oxygen copper having an oxygen content of 30 ppm or less, more preferably Is a conductor of low oxygen copper or oxygen-free copper of 20 ppm or less. If the oxygen content is 30 ppm or less, when the conductor is melted with heat to prevent welding, voids due to oxygen contained in the welded portion are not generated, and the electrical resistance of the welded portion is prevented from deteriorating. The strength of the welded portion can be maintained.
Also, the conductor has a flat rectangular cross section, and it is desirable that the conductor has a shape with chamfers (radius r) at the four corners in terms of suppressing partial discharge from the corner. In addition, the shape of the conductor is not limited to a quadrangle, but may be a polygonal cross section.

  The coating layer 2 provided on the outside of the conductor 1 may be a single layer or a multilayer. 30-200 micrometers is preferable and, as for the thickness of the plane part of the coating layer 2, 80-150 micrometers is more preferable.

In the present invention, the outermost layer of the thermoplastic resin coating layer 2 is preferably an extrusion coating resin layer.
The thermoplastic resin used for the extrusion-coated resin layer may be anything as long as it can be extruded, but in order to reduce the partial discharge generation voltage, those having a relative dielectric constant of 4.5 or less are preferable. For example, polypropylene (PP), polymethylpentene (PMP), polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-ethylene copolymer (ETFE), tetrafluoro Ethylene / perfluoroalkyl vinyl ether copolymer (PFA), polyamide (PA), polyester (PE), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyphenylene ether (PPE), polyether ether ketone (PEEK), Aromatic polyester, polyimide (PI), alicyclic olefin, polyetherimide (PEI), polyamideimide (PAI), polyethersulfone (PES), polyphenylene sulfide PPS), shea Nji syndiotactic polystyrene (SPS), polyketone (PK), polysulfone (PSU), polyphenyl sulfone (PPSU), polyacetal (POM) or the like. More preferably, the dielectric constant is 4.0 or less.

  Here, the relative dielectric constant can be measured with a commercially available dielectric constant measuring apparatus. The measurement temperature and frequency are changed as necessary. In the present invention, unless otherwise specified, it means values measured at 25 ° C. and 50 Hz.

In the present invention, an enamel layer may be provided as one of the thermoplastic resin coating layers 2 between the conductor 1 and the extrusion coating resin layer.
The enamel layer is formed by applying and baking a resin varnish on a conductor a plurality of times. The method of applying the resin varnish may be a conventional method. For example, a method of using a varnish application die having a similar conductor shape, or a “universal die formed in a cross-beam shape if the conductor cross-sectional shape is a quadrangle” Can be used. The conductors coated with these resin varnishes are baked in a baking furnace in the usual manner. Although the specific baking conditions depend on the shape of the furnace used, etc., in the case of a natural convection type vertical furnace of about 5 m, the passage time is set to 10 to 90 seconds at 400 to 500 ° C. Can be achieved.

As the enamel resin forming the enamel layer, conventionally used thermoplastic resins can be used, for example, polyimide, polyamideimide, polyesterimide, polyetherimide, polyimide hydantoin-modified polyester, polyamide, formal, polyurethane, Examples thereof include polyester, polyvinyl formal, epoxy, and polyhydantoin. Preferred are polyimide resins such as polyimide, polyamideimide, polyesterimide, polyetherimide, and polyimide hydantoin-modified polyester, which are excellent in heat resistance.
Moreover, these may be used individually by 1 type, and may mix and use 2 or more types.

The thickness of the enamel layer is preferably 50 μm or less, and more preferably 40 μm or less, in order to reduce the number of passes through the baking furnace and prevent the adhesive force between the conductor and the enamel layer from being extremely reduced. Moreover, in order not to impair the withstand voltage characteristics and the heat resistance characteristics, which are characteristics necessary for an enameled wire as an insulating wire, it is preferable that the enamel layer has a certain thickness. The lower limit thickness of the enamel layer is not particularly limited as long as it does not cause pinholes, and is preferably 3 μm or more, more preferably 6 μm or more.
The enamel layer may be a single layer or a plurality of layers.

In the present invention, an adhesive layer is provided as one of the thermoplastic resin coating layers 2 between the enamel layer and the extrusion-coated resin layer, and the adhesive force between the enamel layer and the extrusion-coated resin layer using the adhesive layer as a medium. May be strengthened.
For example, varnished resin is baked on the outer periphery of the enamel layer to make it an adhesive layer, and in the subsequent extrusion coating process, the extrusion coating is in a molten state at a temperature higher than the glass transition temperature of the resin used for the adhesive layer By making it contact with resin, an enamel layer and an extrusion coating resin layer can be heat-seal | fused.

If the adhesive force between the extrusion-coated resin layer and the enamel layer is not sufficient, when severe processing conditions such as bending to a small radius, wrinkles of the extrusion-coated resin layer may occur inside the bending arc. is there. When such wrinkles occur, a space is generated between the enamel layer and the extrusion-coated resin layer, which may lead to a phenomenon that the partial discharge generation voltage decreases.
In order to prevent this decrease in the partial discharge generation voltage, it is necessary to prevent wrinkles from occurring inside the arc of bending, and a layer having an adhesive function is introduced between the enamel layer and the extrusion coating resin layer. By increasing the adhesive strength, the generation of wrinkles as described above can be prevented.

  Any resin can be used for the adhesive layer as long as it can be heat-sealed. However, since the resin needs to be varnished, it is preferably an amorphous resin that is easily dissolved in a solvent. Furthermore, in order not to lower the heat resistance as an insulated wire, a resin having excellent heat resistance is preferable. Considering these matters, preferred resins include polysulfone (PSU), polyethersulfone (PES), polyetherimide (PEI), polyphenylsulfone (PPSU), polyamideimide (PAI), polyimide (PI) and the like. PES and PPSU are more preferable.

The solvent used for varnishing may be any solvent that can dissolve the selected resin. However, in order to improve the adhesiveness with the enamel layer that is the base when baking to the enamel layer, the base is used. The same solvent used when baking the enamel layer is preferred.
Further, the thickness of the adhesive layer is preferably 2 to 20 μm, and more preferably 5 to 10 μm. In order to sufficiently heat-bond the adhesive layer and the extrusion-coated resin layer, the resin temperature in the extrusion coating process needs to be equal to or higher than the Tg (glass transition temperature) of the resin selected for the adhesive layer, preferably from Tg Also, a temperature higher by 30 ° C. or higher, more preferably a temperature higher by 50 ° C. or higher than Tg is preferable.

  In the insulated wire of the present invention, the thermoplastic resin coating layer 2 may be provided directly on the conductor 1 or may be provided indirectly on a base coating layer provided thereon.

  In the insulated wire of the present invention, at least one protrusion 3 is provided in the longitudinal direction of the insulated wire on the outermost layer of the covering layer 2, preferably the outermost layer of the covering layer 2 on each surface. The protrusion 3 can be formed, for example, by forming simultaneously with the coating layer 2 by making the shape in accordance with the protrusion to be provided with the shape of the die hole in extrusion molding.

  The protrusion 3 has such a strength that the protrusion is not substantially lost by the compression stress received by the compression by the slot into which the insulated wire is inserted and / or the adjacent insulated wire when the wound coil is used. Is preferred. The protrusions have a function of ensuring a certain distance between the insulated wires or between the insulated wires and the slot inner wall. Here, the “strength that does not substantially lose the protrusion” means that the effect of the protrusion is maintained, and the height of 50 to 200 μm is maintained when used as a coil. It means a certain level of strength. The above-mentioned strength can be obtained by appropriately selecting the material of the outermost layer of the thermoplastic resin coating layer and the size of the protrusions corresponding to the compressive strength when used.

The shape of the protrusion 3 is not particularly limited, but the top direction of the top as shown in the drawing is that the concentration of the electric field exceeding the electric discharge start electric field where corona discharge may occur is reduced. it is preferred that the shape is a convex curved surface in the short side direction of the insulated wire. The shape of the convex curved surface at the top is preferably a smooth convex curved surface having a substantially arc shape, and more preferably not changed during the compression. In FIG. 3, the expanded sectional view of a projection part is shown. The symbols have the same meaning as shown in FIG.

  Further, the shape of the protrusion is not limited to the shape having a convex curved surface as shown in the figure. For example, when the cross section is a quadrangle, when the protrusion and the core of the slot are in close contact, there is no gap between them. Therefore, it is a preferable shape for suppressing corona discharge. However, if there is a gap, the electric field concentrates on the edge portion of the protrusion. Therefore, when making the protrusion square, it is preferable that the core and the protrusion are always in close contact with each other.

The height of the uppermost portion of the protrusion 3 indicated by a in FIG. 3 is preferably 50 to 200 μm when subjected to the compressive stress during compression from the outer surface of the flat portion of the thermoplastic resin coating layer 2. 100 to 150 μm is more preferable. Height a is prone to decrease the discharge start voltage too low, and if the height a is too high, then the coil, becomes as space factor when placed in stator slots is small.

  In the electric field distribution when the top of the protrusion 2 is a convex curved surface, the electric field is concentrated on the apex of the protrusion. Higher performance can be expected if the electric field concentration at the apex of the convex curved surface can be relaxed. As the width of the protrusion increases, the electric field concentration at the end of the convex curved surface is reduced. This is due to the fact that the larger the width, the larger the angle formed by the end of the convex curved surface and the larger the gap at the end.

  In FIG. 3, the width of the protrusion indicated by b is preferably 100 to 300 μm, and more preferably 160 to 200 μm. If the width b is too small, the electric field relaxation effect may not be sufficiently obtained. On the other hand, if the width b is too large, the cross-sectional area of the insulating film that becomes a dead space inside the slot increases.

  If the shape of the protrusion in FIG. 3 is an arc for convenience of explanation, it can be seen that as the radius of the arc increases, the electric field at the apex of the arc slightly decreases and the electric field at the end of the arc increases. These are due to the fact that, when the radius is increased, the electric field concentration at the apex can be relaxed, but the angle formed by the arc ends is close to a right angle, which causes electric field concentration. When the radius is used as a parameter in this way, the electric field at the arc apex and the end is in a trade-off, and therefore it is preferable to set it to an appropriate magnitude in consideration of the discharge start electric field. The shape of the protrusion is desirably a convex curved surface, and in particular, it is desirable to have a curved surface that is smooth enough to correspond to an arc shape having a radius of about 100 to 200 μm.

  One protrusion 3 may be provided on each surface of the flat wire, or a plurality of protrusions 3 may be provided. When the number of protrusions is too large, it is not different from simple thickening, so it is preferable to set the number to 3 or less. When there are a plurality of protrusions, it is preferable that the intervals between the protrusions be equally divided. In addition, it is preferable that the protrusion 3 is provided at a position where it does not collide with any surface of the insulated electricity because an increase in dead space can be suppressed when inserted into the slot.

  The insulated wire of the present invention is wound to form a coil and inserted into a status lot for use, but there is no particular limitation on the method of forming the coil, and any method can be used according to the shape of the status lot. It is preferable to wind.

It is a cross-sectional view which shows one embodiment of the insulated wire of this invention. It is a top view which shows one embodiment of the insulated wire of this invention. It is an expanded sectional view of a projection part.

Explanation of symbols

1 conductor 2 thermoplastic resin coating layer 3 protrusion

Claims (1)

A flat wire insulated wire that is wound to form a coil,
The insulated wire has a thermoplastic resin coating layer formed directly or indirectly on the conductor, and a protrusion is provided on the outermost layer of the thermoplastic resin coating layer.
When the coil formed by winding is used, the protrusion has such a strength that the protrusion is not substantially lost due to the compressive stress received by the slot into which the insulated wire is inserted and / or the adjacent insulated wire. ,
The outer shape in the short direction of the insulated wire at the top of the protrusion is a convex curved surface in which the outer shape of the cross section in the short direction of the top of the protrusion is an arc shape with a radius of 100 to 200 μm. Insulated wire.

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