EP2171730B1 - Electric coil - Google Patents

Description

The invention relates to an electrical coil according to the preamble of patent claim 1 and a method for contacting a coil and an arrangement of a coil and two contacts of an electrical supply line.

Such coils are well known. In these known coils, the individual windings, the start winding, the main winding and the end winding are wound separately on a bobbin and the respective end portions of the individual windings are soldered or welded together. This approach is very expensive to manufacture, and through the solder joints or welds the entire coil assembly contains potential sources of error, as in this area contact resistances or in the course of the life of such a coil arrangement and interruptions of the current flow, for example, due to mechanical vibrations breaking solder joints occur. In addition, the windings must be placed in part on the soldering or welding joints. US4759120 discloses a unitary electrical coil which, by means of its windings, is fixed on a circuit board. The fixation requires here several taps which divide the coil at several points. A wire diameter is not considered here.

Object of the present invention is to design a generic coil so that the manufacturing process is simplified and the error rate of the finished product is reduced. In addition, the coil should be contacted as easily as possible. This has hitherto been particularly difficult when wires having a diameter of 50 μm or less are used, because such thin wires are difficult to contact with conventional methods due to their lack of rigidity. Both the production of the coils and their Incidentally, contacting should also be easy, quick and, above all, error-free, even in the case of production of large series.

This object is achieved by the features specified in the independent claims.

The provision of a single winding wire for the main winding, the start winding and the end winding, no junctions between the respective windings occur, whereby both the manufacturing process is simplified and accelerated, and reduces the susceptibility to errors and thus the life of the coil assembly is increased.

Advantageous developments of the electric coil according to the invention are specified in the subclaims.

Preferably, at least the main winding, preferably also the start winding, is wound directly on the spool core. In this embodiment can be dispensed with an additional bobbin, so that the cost of producing a coil fall and also the size of the coil is reduced in the radial direction. The bobbin can in principle have any cross-section, in question are in particular a rectangular or a circular cross-section.

The bobbin has been preferably processed (trowalisiert) using a vibratory finishing process, so that its surface is free of burrs and bumps.

It is also advantageous if the coil core is provided, at least in the region of the main winding, with an insulation layer preferably applied to the coil core, and if at least the main winding, preferably also the start winding, is wound onto the insulation layer. The provision of this insulating layer increases the reliability of the coil assembly by reducing the risk that the insulation surrounding the winding wire will chafe on the coil core. It takes the applied directly on the spool core Insulation layer, in contrast to a provided in the prior art additional bobbin a only insignificant additional radial space. The insulating layer may consist of a wound around the bobbin suitable insulating tape. However, it is preferable, in particular when the coils are produced in larger series, to form a polymer layer which is applied to the coil core by means of a suitable coating method. For example, a parylene coating that has been produced by chemical vapor deposition is particularly well suited. This type of coating is characterized, inter alia, by its good electrical insulation properties even with very thin layers.

According to one embodiment of the invention, the end winding surrounds a portion of the main winding. In this case, the position of the end winding on the main winding can be freely selected, so that any, only determined by the requirements of the intended application of the coil position of the end winding can be selected. In addition, this arrangement allows a comparatively compact design.

According to an alternative embodiment, both the end and the start winding lie on the outside of the central main winding. This arrangement results in an overall flatter coil, which depending on the available space can be beneficial.

Another particularly advantageous embodiment of the invention is characterized in that the respective number of turns of the coil wire of the start winding and the end winding is dimensioned such that the respective electrical effectiveness of the start winding and the end winding after contacting with respective electrical leads within predetermined tolerances , In this way, the electrical efficiency of the entire coil can be precisely determined during manufacture and kept within a predetermined tolerance range so that the manufacturing quality is significantly improved over conventional manufacturing methods.

The coil wire is coated as usual with a lacquer, preferably with a so-called baked enamel, that is with a glue coat whose adhesive effect is activated by heat. The present invention is particularly suitable for very small coils using very thin wire according to the invention having a diameter in the range of less than 50 μm.

In a method according to the invention for contacting a coil, in particular a coil according to the invention, a first contact of an electrical lead to be connected to the start winding is electrically conductively connected to at least one outer turn of the start winding, and a second contact to be connected to the end winding an electrical lead is electrically connected to at least one outer turn of the end winding.

The connection between the contacts of the electrical supply line and the starting or the end winding is produced according to the invention by welding or soldering, wherein in each case a plurality of turns of the starting or the end winding can be electrically connected to the respective contacts of the electrical supply line , Preferably, a suitable laser is used for welding or soldering.

According to a particularly advantageous embodiment of the invention, the contacts of the electrical lead in each case in a mounting area a recess, wherein the first connection area is placed on the winding to be contacted when making the connection, that this depression contacts the winding, and then a laser beam in Area of the recess is directed to the mounting area. This depression is preferably channel-shaped, with a V-shaped or U-shaped cross-section having proved to be particularly advantageous. The attachment region of the contact can be formed from a simple metal sheet, for example a copper sheet which is provided with the V-shaped or a U-shaped profile to form the preferably groove-shaped recess. In this case, the connection is then a welded connection, since the copper sheet is directly connected to one or more coil wires. In order to achieve the necessary high temperature (here the melting temperature of the copper), a laser with a correspondingly high energy density must be used.

Alternatively, the attachment area in the region of its recess can also be on its outside, i. be coated on the side facing in the direction of the coil with a solder, so that with the help of the laser, a solder joint is produced. In this case, both a brazing alloy, such as the silver-phosphor mixture sold under the trade name Silfos, and a soft solder, such as, for example, tin, can be used. In order to produce the appropriate temperatures, lasers with a lower energy density are sufficient.

During the welding or soldering process, the possibly coated with a solder sheet heats up, so that the paint or baked enamel layer, with which the wires are coated, becomes plastic. The sheet sinks with the preferably groove-shaped recess in front between the turns of the winding to be contacted and displaces the plasticized baked enamel. The result is a welded or soldered connection between the provided with a groove attachment region of the contact and the wires of the uppermost turns of the winding to be contacted, via which the desired electrical connection is made.

The quality of the weld or solder connection between the wires of the coil and the contacts is determined primarily by the coupling of the laser beam into the material. Uneven surface structures result in an uneven and hardly predictable coupling. Due to the recess formed in the mounting area a significant improvement is achieved here. The laser beam directed into the depression becomes on its lateral walls reflected, so that the energy evenly distributed in a well-defined area. A particularly good contact is achieved with a groove-shaped depression. This can basically have any cross section. To be particularly advantageous, a substantially V-shaped profile has been found, a U-shaped cross-section is also conceivable.

According to a particularly preferred embodiment of the invention, the number of electrically conductively connected to the respective contact turns is selected so that the electrical properties of the entire coil are within predetermined tolerances. For this purpose, for example, during welding or soldering, an electrical quantity, such as the resistance, of the coil can be measured. If one reaches the desired value, the laser beam is interrupted, so that the joining process is interrupted. In this way, the coil can be assembled so that the start winding and the end winding are negligible with respect to the overall electrical properties of the coil. The electrical properties of the coil are thus determined almost exclusively by the main winding.

Preferably, in the method according to the invention, the first contact of the electrical supply line to be connected to the start winding is electrically conductively connected to at least one winding located below the outer windings of the starting winding.

Further preferably, in the method according to the invention, the second contact of the electrical supply line to be connected to the end winding is electrically conductively connected to at least one winding located below the outer windings of the end winding.

The present invention also relates to an arrangement of a coil of the type described and two contacts of an electrical lead, wherein a first contact with the start winding of the coil is electrically connected, and a second contact with the end winding of the coil is electrically connected: both contacts each have a preferably groove-shaped recess in a mounting area, and this depression is located in each case between the outer turns of the start or end winding.

• Fig. 1: eine Draufsicht auf eine erfindungsgemäße Spule,
• Fig. 2: eine perspektivische Darstellung einer Anordnung aus einer Spule und zwei Kontakten einer elektrischen Zuleitung, und
• Fig. 3: eine schematische Darstellung eines Befestigungsbereiches eines Kontaktes beim Kontaktieren einer Spule.

The invention will be explained in more detail below by means of an example with reference to the drawings. The figures show in detail:

• Fig. 1 : a plan view of a coil according to the invention,
• Fig. 2 a perspective view of an arrangement of a coil and two contacts of an electrical supply line, and
• Fig. 3 : a schematic representation of a mounting area of a contact when contacting a coil.

The coil 1 has a coil core 10, which preferably consists of a silicon-iron alloy (SiFe) or a nickel-iron alloy (NiFe). The surface of the bobbin is tumbled (trowelled) so that no burrs or bumps remain. The bobbin 10 is provided along the coil axis A with a central coil portion 11. The central coil portion 11 is provided at its periphery with an insulating layer 12 which is formed by an electrically insulating adhesive tape which is adhered to the periphery of the central coil portion 11. Alternatively, the insulating layer 12 may also be otherwise applied, for example by coating or painting the central coil section 11, e.g. with a parylene coating, as already mentioned above. In the figures, a spool core 10 is shown with a rectangular cross-section. However, a circular or oval cross-section is also conceivable. Incidentally, the insulating layer 12 may be omitted.

In the region of the first axial end of the middle coil section 11, a start winding 14, which comprises a plurality of turns of an electrically conductive coil wire, is wound coaxially around the coil axis A on the insulation layer 12. The first dashed line in the figure The other end of the start winding 14 is guided out laterally from the start winding 14 in the axial direction and forms a first connecting wire 15 between the start winding 14 and a main winding 16 spaced therefrom in the axial direction of the same. The main winding 16 consists of a plurality of axially juxtaposed and radially superposed turns of the coil wire, which is the same winding wire, as the coil wire of the start winding 14. The coil wire is coated with a so-called baked enamel or adhesive coating. The main winding 16 extends to the vicinity of the second end of the central coil portion 11 and is also wound on the insulating layer 12 surrounding the central coil portion 11. The end of the main winding 16 lies on the radially outer circumference of the main winding 16 and is guided there as a second connecting wire 17 to a structurally predetermined location on the outer circumference of the main winding 16, where the coil wire forms a consisting of a plurality of windings end winding 18, the Main winding 16 surrounds. The second free end 19 of the three coil wires and the two connecting wires forming winding wire is thus located on the radially outer periphery of the end winding 18.

According to a variant, not shown in the figures, the end winding may also be arranged symmetrically to the start winding. In this case, it does not surround the main winding, but is located in the region of the second axial end of the central coil section and thus axially adjacent to the main winding. The basic principle is the same in both variants, since only one wire is used in this variant as well. Which arrangement of start, main and end winding you choose depends in particular on the existing installation space and possible specifications of the position of the contacts.

After completion of the coil, the start winding 14 and the end winding 18 are each with in Fig. 2 shown contacts 20, 20 'a electrical supply by welding or soldering electrically connected.

How to get in Fig. 2 sees, the contacts 20, 20 'each end in an elongated flexible tongue 22, 22', which consists of a thin copper sheet. The other end of the contacts 20, 20 'is connected to electrical leads, not shown here. However, it is primarily the tongues 22, 22 'that are used to make contact with the coil according to the invention that are important to the present invention. These tongues 22, 22 'are in a mounting area, which in Fig. 3 enlarged and shown in section, provided with a groove-shaped recess 24 which has a substantially V-shaped cross-section. This V-shaped groove extends in relation to the tongue 22 or 22 'in the longitudinal direction, and thus parallel to the turns of the start or development 14, 18 (see. FIGS. 2 and 3 ). In the embodiment shown in the figures, the groove-like recess 24 in the attachment region of the contacts, although a V-shaped cross section, a U-shaped cross-section, any other channel shapes or a simple crater-like depression are also conceivable.

The method for establishing the connection between the start winding 14 and the end winding 18 and the respectively associated contact 20 ', 20 will be described below with reference to the end winding 18; It is analogously applied but also for contacting the start winding.

First, the possibly pre-heated mounting portion of the tongue 22 of the contact 20 is pressed radially onto the end winding 18, wherein the groove-shaped recess 24 comes to rest with its lowest point on the outer turns of the end winding 18. The radial contact pressure is in FIG. 3 indicated by arrows F. As in FIG. 3 Subsequently, a laser beam 40 is directed into the V-shaped recess. As a result, the thin copper sheet of the tongue 22 is heated in the region of the recess 24. Due to the "bundling" of the laser beam through the side walls of the channel-shaped Deepening results in a uniform heating and a uniform and predictable coupling of the laser beam 40. Due to the heat that occurs, the baked-enamel shell softens around the wires of those turns 27 which lie directly below the fastening region of the contact 20. The attachment area thus penetrates between the turns by the action of contact pressure and laser beam 40 with the V-shaped tip in front, displacing the plasticized baked enamel. An uncontrolled caking of the wires together is avoided, and obtained by the plasticized and displaced enamel shell the desired stripping of the contacted wire.

With the described method, a solder joint can be prepared, in which case the pointing in the direction of the coil outside of the tongue 22 is coated in advance with a solder. This solder is softened by the heat generated by the laser beam 40 and in principle also bonds with the wires of the winding to be contacted, as described above for the uncoated tongue 22.

Depending on the strength of the contact pressure and depending on how long the laser beam 40 is directed into the V-shaped recess 24 of the tongue 22, more or fewer turns 27 are electrically contacted. The above factors can be set to contact as many turns as required to maintain the electrical properties of the coil (e.g., impedance or total electrical resistance) within predetermined tolerances. For example, during the contacting process, one can electronically monitor the resistance or other electrical size of the coil, giving a signal to complete the welding or soldering process when a desired value is reached.

Both the position of the start winding 13 along the axis A on the central coil section 11, as well as the position of the end winding 18 in the axial direction on the main winding 16 is arbitrary, so that this situation after the constructive boundary conditions of the later Application of the coil can judge, for example, the position of the electrical leads at the later mounting location of the coil is decisive.

The number of turns of the start winding 14 and the end winding 18 is calculated so that the electrical effectiveness of both the start winding 14, and the end winding 18 is only within predetermined tolerances, so that the start winding 14 and the end winding 18 with respect to the entire electrical properties of the coil are insignificant. The electrical properties of the coil are thus determined almost exclusively by the main winding 16.

The invention is not limited to the above embodiment, which merely serves to generally explain the essence of the invention. Within the scope of protection, the device according to the invention may also assume other than the above-described embodiments. In this case, the device may in particular have features that represent a combination of the respective individual features of the claims.

Reference signs in the claims, the description and the drawings are only for the better understanding of the invention and are not intended to limit the scope.

Claims (13)

1. Electric coil with

   • a coil core (10),

   • a main winding (16) surrounding the coil core (10) and having an electrically conductive coil wire;

   • a start winding (14) surrounding the coil core (10) and having an electrically conductive coil wire, which is intended to be connected to a first contact; and

   • an end winding (18) surrounding the coil core (10) and having an electrically conductive coil wire, which is intended to be connected to a second contact;

   characterised in that

   • the coil wire of the main winding (16), the coil wire of the start winding (14) and the coil wire of the end winding (18) are formed by a continuous winding wire, and at least the main winding (16), preferably also the start winding (14), is wound directly onto the coil core (10), wherein the coil wire has a diameter of 50 µm at most.
2. Electric coil according to claim 1, characterised in that at least in the region of the main winding (16) the coil core (10) is provided with an insulation layer (12) preferably applied to the coil core (10), and that at least the main winding (16), preferably also the start winding (14), is wound onto the insulation layer (12).
3. Electric coil according to claim 2, characterised in that the insulation layer (12) is a coating composed of a polymer coating material, which is preferably applied to the coil core (10) by means of vapour deposition.
4. Electric coil according to one of the preceding claims, characterised in that the end winding (18) surrounds a section of the main winding (16).
5. Electric coil according to one of the preceding claims, characterised in that the respective number of windings of the coil wire of the start winding (14) and of the end winding (18) is dimensioned so that the respective electrical efficacy of the start winding (14) and the end winding (18) lies within predefined tolerances after contacting with respective electrical supply lines has been accomplished.
6. Method for contacting a coil according to one of the preceding claims, in which a first contact (20') of an electrical supply line to be connected to the start winding (14) is connected electrically conductively to at least one outer winding of the start winding (14), and
   in which a second contact (20) of an electrical supply line to be connected to an end winding (18) is connected electrically conductively to at least one outer winding (27) of the end winding (18),
   characterised in that the connection is produced by welding or soldering, preferably using a laser beam (40), wherein multiple windings (27) of the start or the end winding (14; 18) are respectively connected electrically conductively to the respective contacts (20, 20') of the electrical supply line.
7. Method for contacting a coil according to claim 6, characterised in that the contacts (20, 20') of the electrical supply line have a recess (24) in a respective fastening region (22, 22'), wherein during production of the connection the fastening region is firstly placed onto the winding (14, 18) to be contacted so that the recess (24) touches the winding (14, 18), and then a laser beam (40) is directed onto the fastening region (22, 22') in the region of the recess (24).
8. Method for contacting a coil according to claim 7, characterised in that the recess (24) is groove-shaped and preferably has a substantially V- or U-shaped profile.
9. Method for contacting a coil according to claim 7 or 8, characterised in that in the region of its recess (24) the fastening region (22, 22') is coated with a solder on its outer surface pointing in the direction of the coil.
10. Method according to one of claims 6 to 9, characterised in that the first contact (20') of the electrical supply line to be connected to the start winding (14) is connected electrically conductively to at least one winding located below the outer windings of the start winding (18).
11. Method according to one of claims 6 to 10, characterised in that the second contact (20) of the electrical supply line to be connected to the end winding (18) is connected electrically conductively to at least one winding located below the outer windings of the end winding (18).
12. Method for contacting a coil according to one of claims 6 to 11, characterised in that the number of windings (27) connected electrically conductively to the respective contact (20, 20') is selected so that the electrical properties of the entire coil lie within predefined tolerances.
13. Arrangement comprising a coil according to one of claims 1 to 5 and two contacts (20, 20') of an electrical supply line, wherein a first contact (20') is connected electrically conductively to the start winding (14) of the coil, and a second contact (20) is connected electrically conductively to the end winding (18) of the coil, both contacts (20, 20') having a preferably groove-shaped recess (24) in a respective fastening region (22, 22'), the deepest point of which viewed in cross-section respectively sits between the outer windings of the start or end winding.

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