CLIMATE-PROOF SOLENOID COIL

Description

[0001] The invention relates to a climate-resistant magnetic coil with its insulation structure and a method for its production for the installation of the magnetic coil in an open iron core (yoke) as a supporting magnetic coil under a magnetic levitation train.

[0002] A number of technical solutions for magnetic levitation vehicles are known, using differently designed magnetic coils, each designed as a support, guide, and / or braking magnetic coil. These are generally specially shaped to achieve a sufficiently high magnetic field strength, so that the magnetic levitation vehicles can be hovered and / or kept on track and accelerated or decelerated accordingly. A basic requirement is the smallest possible air gap between the magnetic coil and the object to be kept in suspension, for example, in order to achieve high energy efficiency. This is particularly achievable with large-area, flat magnetic coils. An example of such a flat magnetic coil is DE 39 07 831 C2, which describes a highly heat-resistant compact magnetic coil specifically for magnetic levitation technology.To make the coil highly heat-resistant and climate-resistant, insulated metal foils are wound onto a rectangular iron core. However, this coil is only suitable for low magnetic field strengths. It is also known from US Pat. No. 3,462,244 to sheathe a cable with a glass fabric material to increase the heat resistance of such a magnetic coil.

[0003] DE 33 46 031 A1 discloses a coil insulation process in which two different insulation layers are applied to a molded magnetic coil. In a first insulation step, a mica foil or mica tape is wound in a semi-overlapping manner around the sections of the coil that lie in the groove of a laminated core. The coil ends are also insulated in the first step. Once the coils are mounted, they are then coated with a thermally curable epoxy resin or a special powder coating in a second insulation step. The resin is applied primarily to the coil ends and cured by heating, creating a second, high-strength insulation layer. This process is relatively complex and not suitable for electrical machines or magnetic coils subject to high thermal stress.

[0004] Furthermore, DE 10 2017 222 426 A1 (WO 2016 / 244685) describes an armature for a linear motor and a linear motor in which the armature (core) of the linear motor, i.e. the magnetic coils, are fully covered on the outside by a special protective film. This full-surface protective film consists of a glass fabric material or a carbon fiber fabric material and is additionally designed so that it can be impregnated with a resin. Epoxy resin, phenolic resin or acrylic resin are proposed for impregnation in this technical solution. This protective film with the additional resin layer is intended to reliably prevent the penetration of foreign bodies and, above all, any penetration of liquids impacting the armature, such as splash water. This solution is cost-intensive and the protective film with the applied resin layer further enlarges the air gap.

[0005] The use of heat-shrink tubing in electrical engineering is documented in DE 100 23 204 A1. This involves completely insulating stator windings for DC and AC machines using fully enveloping heat-shrink tubing. These tubings are pushed over the entire bar winding of the machines and then shrunk using heat treatment to achieve sufficient, even liquid-tight, insulation. This technical solution is also time-consuming and therefore expensive.

[0006] WO 2017 026306 A1 describes an insulating resin coating process for a stator of a rotating electrical machine. In this process, the individual welded circuit connections of a stator are first enclosed in a two-part resin mold, into which a resin is then injected, the resin is cured, and the mold is subsequently removed. This achieves full-surface, weatherproof insulation of the bare circuit connections.

[0007] DE 42 370 70 A1 describes the use of elastic insulating sheaths or insulating stumps made of impregnable fiber-reinforced fabric materials for the switching connections of large electrical machines, which are pushed over the switching connections to be insulated and then impregnated in a vacuum impregnation system using the so-called full impregnation technique, both in vacuum and under pressure (VPI impregnation), and then cured.

[0008] JP H07 169 615 A ​​describes a preformed coil with high dielectric strength, wherein the amount of partial discharge is kept low between inner insulating layers when a high voltage is applied. A special intermediate layer is applied in which a conductor is insulated, which surrounds each turn except for the turn of the innermost layer and the turn of the outermost layer, forming a type of inner insert coil. The coil is wound with an epoxy resin-impregnated prepreg mica tape, and another insulating intermediate layer is inserted, which forms the turn of the innermost layer and the turn of the outermost layer. The insulating intermediate layer is created by inserting an epoxy-impregnated prepreg mica tape between it and the adjacent layer. This prepreg is heated and pressed to produce the inner insert coil.Therefore, the pressure on the interlayer insulating layer becomes uniform across the entire surface, and an interlayer insulating layer with favorable dielectric strength can be obtained. Finally, this inner insert coil is resin-encapsulated to produce a molded coil. JP S58 57711 A, JP S58 115801 A, and DE 29 45 480 A1 disclose further magnetic coils.

[0009] The invention is based on the object of creating a climate-resistant magnetic coil and a simple method for its production for later placement and / or insertion over or onto an open iron core (yoke), wherein the coil insulation should have a high water resistance, ensure insulation strength even under extreme climatic conditions, be structurally simple and maintenance-free, be cost-effective to manufacture without complex VPI impregnation processes and also have a long service life.

[0010] The object is achieved according to the invention with the features of the preamble and the characterizing part of the first and second patent claims. Further advantageous embodiments are described in the dependent, reciprocal subclaims. In the climate-resistant magnetic coil 1 according to the invention for placement and / or insertion into or onto an open iron core (yoke), the coil lead-out 2 is effected via a connecting cable 2.1 arranged on the copper coil, which is integrally connected to the copper coil by means of a solder joint. The solder joint 5 is preferably additionally covered with a shrink tube. In a first bonding step, the magnetic coil 1 is bonded, except for the lead-out area, with an epoxy resin-containing prepreg tape 7.

[0011] This also ensures a stronger (adhesive) connection to the final insulation cover strip 8. A trough-shaped fiberglass reinforced fabric sleeve 4 is positioned over the exit area of ​​the connecting cable 2 and the exit for coil monitoring 3, such that it completely covers or encloses the exit area within a defined area. Next, the entire solenoid coil, including the fiberglass reinforced fabric sleeve 4, is completely bonded with an epoxy resin-containing insulation cover strip 8 in a second bonding step. This finished, doubly insulated solenoid coil 1 is then fully cured, welding the insulation into a closed, elastic surface. After the insulation has hardened, an elastic potting compound is applied to the fiberglass reinforced fabric sleeve 4 in a suitable manner.The cured epoxy resin-containing insulation cover strip 8 is severed in the area of ​​one or more arranged openings 6 in the fiberglass-reinforced fabric sleeve 4 to introduce the elastic potting compound. Depending on its composition, this compound cures at normal ambient temperature or can also be accelerated by applying a separate heat input. This manufacturing process results in a highly climate-resistant magnet coil 1 with a sufficiently elastic insulation sleeve, which ensures very high watertightness and maintains the required high and permanent insulation strength over a long period of time, even under extreme climatic conditions.In particular, this makes it possible to permanently guarantee the temperature-related, frequent expansion stresses (usually up to several millimeters per expansion cycle) at the sensitive discharge points of the solenoid coil 1 for the planned service life without leaks and without reducing the insulation strength. This climate-resistant solenoid coil 1 is structurally simple and maintenance-free, can be manufactured cost-effectively, and also has an extended service life expectancy.

[0012] In the climate-resistant solenoid coil 1, one or two or more openings 6 are arranged at suitable locations to facilitate the introduction of the elastic, initially low-viscosity potting compound into the tub-shaped fiberglass reinforced fabric sleeve 4. This allows the initially low-viscosity potting compound to be preferably poured into the fiberglass reinforced fabric sleeve 4 from above without any gas or air pockets remaining. In principle, it is also possible to install the tub-shaped fiberglass reinforced fabric sleeves 4, fully filled with the potting compound, from below over the discharge areas.

[0013] For the climate-resistant magnetic coil 1, the epoxy resin-containing prepreg tape consists of a thin glass fabric with a high epoxy resin content in the range of 125 g / m² + / - 20 g / m². This improves adhesion between the insulation cover tape 8 and the coil wire. By fusing the epoxy resin together, preferably four layers of cover tape, an elastic, mechanically robust, durable, weatherproof, and waterproof insulation is created.

[0014] The elastic casting compound preferably consists of a low-viscosity PUR casting compound. The PUR casting compound can be poured, injected, or pressed in using pressure. Depending on its composition, the PUR casting compound can either cure over a certain period of time at normal ambient temperature or be accelerated by applying a separate heat source.

[0015] The invention will be explained below in an embodiment with reference to Figures 1 and 2 will be explained in more detail. The exemplary embodiment described below relates to a climate-resistant magnetic coil 1 for installation in a magnetic levitation train, whereby the magnetic coils 1 must keep the magnetic levitation train suspended. Therefore, in order to achieve the most effective effect, they are located directly beneath the levitation train without any additional protection and are thus directly exposed to all seasonal weather influences. Fig. 1 shows an oblique plan view of a possible design of a climate-resistant magnetic coil 1 Fig. 2 shows a side view of a magnetic coil 1 with the two layers of the coil insulation, partially shown

[0016] In Figure 11 is an oblique plan view of a possible design of a climate-resistant magnetic coil 1, showing the uninsulated state of a preferred embodiment of a magnetic coil 1 according to the invention. This shows a plurality of windings of a magnetic coil with two coil lead-outs 2 and the associated soldered connecting cables 2.1 and the adjacent lead-outs for coil monitoring 3. The connecting cable 2.1 is soldered to the coil lead-out at the lead-out points, and this soldering point is additionally insulated with a shrink tube 5. On one side, the lead-out area is shown without a cover by a fiberglass hard fabric sleeve 4, and on the other side with the fiberglass hard fabric sleeve 4 already applied, whereby the immediate lead-out area from the magnetic coil 1 is completely covered. A through-opening 6, such as a bore here, is arranged in the fiberglass hard fabric sleeve 4.

[0017] Fig. 2shows a side view of a magnetic coil 1 with the two layers of applied coil insulation, partially shown. The magnetic coil 1 provided with the glass fiber reinforced fabric sleeve 4 is bound in a first binding step without gaps up to the glass fiber reinforced fabric sleeves 4 (i.e. the glass fiber reinforced fabric sleeves 4 are not bound over). Typically, this adhesive layer is bound up at most butt joints so that no overlaps occur during binding. For the first binding of the magnetic coil 1, an epoxy resin-containing prepreg tape 7 is used, which consists of a thin glass fabric with a high epoxy resin content in the range of 125 g / m 2 < + / - 20 g / m 2 <. In a second binding step, an insulating cover tape 8 containing epoxy resin is wound over this first adhesive layer in the opposite direction, preferably in a semi-overlapping manner in two layers, so that the discharge area is also completely covered with the trough-shaped glass fiber hard fabric sleeve 4.This creates four cover layers. Curing then occurs using conventional curing methods involving heat input. After curing, the double-layer insulating cover strip insulation is opened at the location where the opening 6 is located in the fiberglass reinforced fabric sleeve 4 by piercing the insulation with a suitable tool. An elastic, initially low-viscosity PUR casting compound is then pressed through this opening 6 into the trough-shaped fiberglass reinforced fabric sleeve 4 and cured at room temperature. This magnetic coil 1 for a magnetic levitation train with the described insulation structure is extremely waterproof and weather-resistant, simple and cost-effective to manufacture, and has a long service life. List of reference symbols

[0018] 1Solenoid coil 2Coil output 2.1Connecting cable 3Output for coil monitoring 4Glass fiber reinforced fabric sleeve (HGW sleeve) 5Soldering point with shrink tubing 6Opening in the glass fiber reinforced fabric sleeve 7Epoxy resin prepreg tape 8Epoxy resin insulation cover tape

Claims

1. Climate-proof magnetic coil (1) for installation onto a yoke, the magnetic coil (1) comprising a copper coil with a coil lead-out (2) via a connection cable (2.1) positioned on the copper coil and materially bonded to the copper coil by means of a solder joint, the magnetic coil (1) being embedded by means of a prepreg strip (7) containing epoxy resin, as part of the magnetic coil (1), characterized in that over the lead-out area of the connection cable (2.1) and a lead-out (3) of the magnetic coil (1), a trough-shaped laminated glass fibre fabric sleeve (4), as part of the magnetic coil (1), is disposed for coil monitoring such that it fully covers the lead-out area, an elastic potting compound is introduced in the laminated glass fibre fabric sleeve (4), an insulating cover strip (8) containing epoxy resin, as part of the magnetic coil (1), is positioned over the entire magnetic coil (1) including the laminated glass fibre fabric sleeve (4).

2. Process for manufacturing a climate-proof magnetic coil (1), the magnetic coil (1) comprising a copper coil with a coil lead-out (2) via a connection cable (2.1) positioned on the copper coil and materially bonded to the copper coil by means of a solder joint, the magnetic coil (1) being embedded by means of a prepreg strip (7) containing epoxy resin, as part of the magnetic coil (1), characterized in that the lead-out area of the connection cable (2.1) is fully covered with a trough-shaped laminated glass fibre fabric sleeve (4), as part of the magnetic coil (1), an insulating cover strip (8) containing epoxy resin, as part of the magnetic coil (1), is wound over the entire magnetic coil (1) including the laminated glass fibre fabric sleeve (4) and subsequently cured, the insulating cover strip (8) is opened at least in one place, an elastic potting compound is introduced into the trough-shaped laminated glass fibre fabric sleeve (4), which is left to cure on its own or under heat input.

3. Climate-proof magnetic coil (1) according to claim 1, characterized in that one or several openings (6) are positioned in the trough-shaped laminated glass fibre fabric sleeve (4).

4. Climate-proof magnetic coil (1) according to claim 1, characterized in that the prepreg strip containing epoxy resin consists of a thin glass fabric with a high proportion of epoxy resin in the range of 125g / m2 + / - 20 g / m2.

5. Climate-proof magnetic coil (1) according to claim 1, characterized in that the solder joint is formed using a shrink-wrap tube.

6. Method for manufacturing climate-proof magnetic coil (1) according to claim 2, characterized in that the elastic potting compound introduced into the trough-shaped laminated glass fibre fabric sleeve (4) consists of a low-viscosity PUR potting compound, which is introduced by casting, injection moulding or pressing and then left to cure.