EP1105893B1 - Method for producing inductive components - Google Patents

Description

The invention relates to a method for producing inductive Components, in particular current transformers for electricity meters.

Current transformers are inductive components by their design regarding imaging behavior and phase errors the exact Detection of mains currents in industrial meters or household meters enable. Together with an evaluation electronics replace meanwhile the so-called Ferraris measuring instruments (Polyphase meter).

It is well known, but other such current converters inductive components such as transformers for switched Power supplies, chokes and transformers based on Plastic housings glued or cast magnetic cores manufacture. This is in a thermoplastic plastic housing the one or more windings provided Magnet core inserted and with a casting resin, which in usually consists of polyurethane or an epoxy resin, cast around. The lead out of the connection cable of the windings leads to several problems. The lead out of the connection cable through the potting surface requires a precise defined position of the cable during the Vergussvorgangs, so that so-called Vergußpaletten with cable fixations in the rule necessary. The use of such Vergusspaletten is very expensive.

Another possibility is fixing the cable in a double groove on the upper edge of the housing is. Here comes However, it often occurs to exit the casting resin in a row Capillary forces through this groove.

A cable run through a hole in the housing wall requires an additional seal and thus also one greater effort, which is economically disadvantageous.

Object of the present invention is therefore a new Manufacturing method for inductive components, in particular for Current transformers, specify in which the above problems be largely avoided.

1. Bereitstellen einer metallischen Form;

2. Einlegen des mit zumindest einer Wicklung versehenen Magnetkerns in die Form;

3. Schließen der Form;

4. Einfüllen einer aufgeschmolzenen Schmelzklebermasse unter Druck in die Form;

5. Definiertes Abkühlen der Form;

6. Öffnen der Form und Entnahme des umgossenen, induktiven Bauelements.

According to the invention, this object is achieved by a method of producing inductive components with the following steps:

1. providing a metallic mold;

2. inserting the magnetic core provided with at least one winding into the mold;

3. closing the mold;

4. filling a melted melt adhesive mass under pressure into the mold;

5. Defined cooling of the mold;

6. Opening the mold and removal of the cast, inductive component.

This procedure compares the production process considerably simplified to the prior art, which is too noticeable reduced costs.

The molds used are usually made of aluminum or an aluminum alloy that is substantially less expensive are considered to be the injection molds required for the housing used in the prior art. By use These shapes can also be compared to the prior art significantly shorter time-to-market, because the shapes are much easier. This happens quick and easy changes of customized Embodiments of the inductive components.

Preferably, the filling of the molten takes place Hot melt adhesive composition under a pressure of 0 to 20 bar, preferably from about 10 to 20 bar, being used as melt adhesive mass a polyamide-based thermoplastic hot melt adhesive is provided is. This is in particular one non-porous polyamide-based hotmelt adhesive. The usage This polyamide hot melt adhesives opens up significantly better ways of recycling inductive components, because with the inductive components only a single Plastic is used. In particular, various polyamide hot melt adhesives compostable. Furthermore, these must Thermoplastics not necessarily made of fossil Substances such as petroleum or coal, are produced but can also be made from renewable raw materials (wood resins) become.

In one embodiment, the terminals of the winding or the terminals of the windings before inserting the magnetic core into the mold from the mold in a well-defined way led out. As connections while cables are provided. The lead out of these cables takes place directly via grooves in the form, with an exit through the special process is prevented by hot melt adhesive composition.

In another embodiment, the terminals of the winding or the terminals of the windings in the form in blind holes placed. This allows the use of relative rigid connections, so that with the invention Manufacturing process also inductive components are produced can be directly SMD compatible (Service Mounted Device) are.

Preferably, as magnetic cores toroidal cores of metallic Alloys, in particular toroidal cores of amorphous or nanocrystalline alloys. By use of such amorphous or nanocrystalline alloys results over the previously used crystalline Alloys or ferrite cores a significant volume reduction as well as much better technical characteristics of the inductive components of the type mentioned. The advantage and the properties of these amorphous or nanocrystalline Alloys are described, for example, in EP 0 271 657 B1 described in detail.

Figur 1

eine Draufsicht auf einen Stromwandler, der mit dem Verfahren nach der vorliegenden Erfindung hergestellt worden ist, und

Figur 2

einen Schnitt entlang der Linie I-I durch den Stromwandler aus Figur 1.

The invention is illustrated below by way of example with reference to the drawing. Showing:

FIG. 1

a plan view of a current transformer, which has been produced by the method according to the present invention, and

FIG. 2

a section along the line II through the current transformer of Figure 1.

As shown in the figures, there is a according to the invention Method produced current transformer 1 off a magnetic core 2 provided with a secondary winding 3 is. The secondary winding 3 consists mostly of some 100 to some 1000 turns. The secondary winding 3 of this Current transformer 1 consists of relatively thin wire, d. H. the wire has a thickness of 0.05 to 0.25 mm. The ends the secondary winding 3 shown here are as two-wire Litz 5 executed so that the current transformer 1 on a circuit board (not shown) can be connected.

The magnetic core 2 of the current transformer 1 shown here is a Ring band core made of an amorphous alloy. The ring band core with the secondary winding 3 was on the Low-pressure Schmelzgußverfahren according to the invention produced.

In this case, a mold made of an aluminum alloy was provided (Not shown). In this form was the ring band core loaded with the secondary winding 3 thereon, wherein the secondary winding 3, the ends as a two-wire strand 5 are executed, is led out of the mold. Form was closed and in the mold was melted thermoplastic melt adhesive composition based on polyamide introduced a pressure of about 15 bar. This creates around the magnetic core 2 a casting enclosing this 4. In the area the opening of the ring band core, the cast body 4 a through opening 5, through which the primary winding (not shown) of the current transformer 1 can be performed.

Thereafter, the mold was cooled in a defined manner. After cooling the Mold was opened the mold and the molded-on current transformer 1 was taken. After removal of the cast-iron current transformer 1, the gate was removed.

Claims (9)

1. Method of producing inductive components (1) comprising the following steps:

   1) providing a metallic mould;

   2) inserting the magnetic core (2) provided with at least one winding (3) into the mould;

   3) closing the mould;

   4) pouring a molten thermoplastic hot-melt adhesive substance (4) under pressure into the mould;

   5) subjecting the mould to defined cooling, and

   6) opening the mould and removing the encapsulated inductive component.
2. Method according to claim 1, in which the mould consists of aluminium or an aluminium alloy.
3. Method according to claim 1 or claim 2, in which the molten hot-melt adhesive substance is poured in under a pressure of 10 to 20 bar.
4. Method according to one of claims 1 to 3, in which a polyamide-based thermoplastic hot-melt adhesive is provided as the hot-melt adhesive substance.
5. Method according to one of claims 1 to 4, in which the terminals of the winding are brought out of the mould before the magnetic core is inserted into the mould.
6. Method according to one of claims 1 to 4, in which the terminals of the winding are placed in blind holes in the mould.
7. Method according to one of claims 1 to 6, in which a toroidal core consisting of a metallic alloy is used as the magnetic core.
8. Method according to claim 7, characterised in that a strip-wound toroidal core consisting of an amorphous or nanocrystalline alloy is used as the toroidal core.
9. Method according to one of claims I to 8, in which a current sensor is provided as the inductive component.

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