EP1655747A2 - Cut of sheet metal for a laminated transformer core - Google Patents

Abstract

The lamination has a sheet metal component forming a yoke (34), external blades and a middle blade (30) of a section of a core. Another sheet metal component forms another yoke (32), where ends of the blades impinge against a longitudinal side of the yokes in a composite condition of the components, such that two windows are formed. A recess is provided in a portion of each window and via which a surface of the windows is increased.

Description

The invention relates to a sheet metal section for a layered core of a transformer having a first sheet metal part which has an E-shaped basic shape and which forms a first yoke, two outer legs and a middle leg of a layer of the core. The sheet metal section comprises a second sheet metal part which has an I-shaped basic shape and which forms a second yoke of the layer of the core. In the assembled state of the first and the second sheet metal part, the free ends of the legs of the first sheet metal part abut against a longitudinal side of the yoke formed by the second sheet metal part, so that two windows are formed with a rectangular basic shape, which are bounded by the legs and yokes. Such laminations are assembled into layered cores, wherein preferably at least one coil body with coil windings are plugged onto the central web. The bobbin comprises at least one primary winding and / or at least one secondary winding. Further, a bobbin may also be alternatively or additionally provided on one or a respective bobbin on each of the outer limbs of the core.

Such laminations are used for electromagnetic transducers, in particular transformers, which are generally referred to as stationary electrical machines.

Sheet metal cuts for such electromagnetic transducers are specified, for example, in the German industrial standard (DIN). In FIGS. 1 and 2, a sheet-metal section with the designation E130 according to DIN is shown by way of example, with the outlines of the EI section being shown in FIG. In Figure 2, the dimensions for the E130 section according to DIN are additionally indicated. In a sheet metal section according to DIN E130, the Jochmaß, i. the length of the yoke on the E-shaped sheet metal part and the length of the 1-shaped sheet metal part each 30 mm. Such laminations, such as the sheet metal section E130 according to DIN, are preferably used in so-called print transformers, which can be connected directly to a printed circuit. For example, such transformers may have so-called print connections, which are inserted through holes in a printed circuit board and connected on the opposite side of the circuit board by means of a solder connection with circuit traces of a printed circuit located on the circuit board. It is expressly understood that the inventive sheet metal section is not limited to a section with yoke lengths according to the E130 standard but this section only serves to illustrate the sheet metal section according to the invention, so that the inventive sheet metal section can also have much larger yoke dimensions or much smaller yoke dimensions.

Creepage distances between the windings on the bobbins and the core can be formed along the bobbin, which is preferably made of insulating material, especially if the insulating capacity of the bobbin is reduced at least on its surface, in particular by moisture. About such a creepage distance can then flow an undesirable leakage current between the coil winding and the core. creepage generally lead to energy loss and malfunction of the transformer and can pose a danger to the user.

The object of the invention is to provide a sheet metal section for a core of a transformer, are avoided in the unwanted leakage currents in a simple manner.

This object is achieved by a lamination with the features of claim 1. Advantageous developments of the invention are specified in the dependent claims.

By a lamination with the features of claim 1 can be increased in a simple manner, the creepage distances between a wound on a bobbin around the central web winding to the layered core, whereby losses due to leakage currents are reduced or avoided altogether. Due to the additionally provided recesses, at least the outer ends of a bobbin are no longer in direct contact with the core. As a result, leakage currents are effectively avoided even when the coil winding is wound to the outer edge of the bobbin or the insulating capacity of the insulating material is reduced. With the help of the sheet metal section according to the invention coil bobbins can also be wound to the outer edge of the bobbin and there is still a sufficient creepage distance, are low by the possible leakage currents on this route and the resulting losses.

Fig.1

den Umriss eines Blechschnitts E130 nach DIN;

Fig.2

den Blechschnitt nach Fig.1 mit Bemaßung;

Fig.3

eine Vorderansicht eines Printtransformators gemäß einer ersten Ausführungsform der Erfindung;

Fig.4

eine Seitenansicht des Transformators nach Fig.3;

Fig.5

eine Schnittdarstellung des Transformators nach Fig.3 entlang der Schnittlinie A-A;

Fig.6

eine vergrößerte Darstellung des in Fig.5 mit Y bezeichneten Bereichs;

Fig.7

den Umriss eines Blechschnitts des Transformators nach Fig.3;

Fig.8

den Blechschnitt nach Fig.7 mit Bemaßung;

Fig.9

eine Vorderansicht eines Printtransformators gemäß einer zweiten Ausführungsform der Erfindung;

Fig.10

eine Seitenansicht des Transformators nach Fig.9;

Fig.11

eine Schnittdarstellung des Transformators nach Fig.9 entlang der Schnittebene B-B;

Fig.12

eine vergrößerte Darstellung des in Fig.11 mit Z bezeichneten Bereichs;

Fig.13

einen Umriss eines Blechschnitts des Trafos nach Fig.9;

Fig.14

den Blechschnitt nach Fig.13 mit Bemaßung.

For a better understanding of the present invention, reference will now be made to the preferred embodiments illustrated in the drawings, which are described in terms of specific terminology. It should be noted, however, that the scope of the invention is not limited thereby It should be understood that such changes and other modifications to the illustrated devices and / or method, as well as such other uses of the invention as set forth herein, are to be considered as common present or future knowledge of a person skilled in the art. The figures show embodiments of the invention, namely:

Fig.1

the outline of a sheet metal section E130 according to DIN;

Fig.2

the sheet metal section of Figure 1 with dimensioning;

Figure 3

a front view of a print transformer according to a first embodiment of the invention;

Figure 4

a side view of the transformer of Figure 3;

Figure 5

a sectional view of the transformer according to Figure 3 along the section line AA;

Figure 6

an enlarged view of the designated in Figure 5 with Y area.

Figure 7

the outline of a sheet metal section of the transformer of Figure 3;

Figure 8

the sheet metal section of Figure 7 with dimensioning;

Figure 9

a front view of a print transformer according to a second embodiment of the invention;

Figure 10

a side view of the transformer of Figure 9;

Figure 11

a sectional view of the transformer of Figure 9 along the sectional plane BB;

Figure 12

an enlarged view of the designated Z in Figure 11 area;

Figure 13

an outline of a sheet metal section of the transformer of Figure 9;

Figure 14

the sheet metal section of Fig.13 with dimensioning.

FIG. 3 shows a front view of a print transformer 10. Invisible body edges of the print transformer 10 are shown as dashed lines. The print transformer 10 has an outer shell 12, which is made of a plastic, for example. In the interior of the shell 12, a layer 16 of laminations laminated core 16 is arranged, which contains two outer webs and a central web, each adjacent to one end of a yoke and pass into a yoke. Around the central web of the core 16, a bobbin 18 is arranged, on which at least one winding 20, for example made of copper wire, is wound. The laminations are also referred to as laminations.

From the interior of the transformer 10 are pins 14a to 14d, so-called connection pins, down out so that they protrude down over a lower edge 15 of the shell 12. The connection pins 14a to 14d may be, for example are inserted through holes in a circuit board and then connected on the opposite side of the print transformer 10 side of the circuit board with conductor tracks of a printed circuit existing there by means of a solder joint. The ends of the windings 20 located on the bobbin 18 are electrically connected to connection elements 22a to 22e, which are arranged on a carrier 24 in the interior of the shell 12 of the transformer 10. Although the terminal pin 22c is provided on the carrier 24 in the embodiment shown in Fig. 3, it is not used. In other embodiments, for example, have two primary and / or two secondary windings, the connection element 22c is used. The connection elements 22a and 22e are electrically connected to the connection terminals 14a and 14d respectively, the primary voltage being supplied via the connection pins 14a and 14d. The connection elements 22b and 22d are electrically connected to the connection pins 14b and 14c, respectively.

Via the connection pins 14b and 14c, the secondary voltage is led out of the transformer 10. For example, the print transformer 10 in the region of the connection pins 14a to 14d coated with a coating material, such as a thermoplastic or thermoset, and / or potted with a potting compound, so that at least a portion of the support 24 and a portion of the connection elements 22a of the overmolding material or the potting compound are enclosed and only the connection pins 14a to 14d protrude from the overmolding material or the potting compound. Preferably, the potting compound is inserted into the shell 12 when the print transformer 10 is rotated 180 °, so that the bottom 15 is facing up and the shell 12 forms an upwardly open vessel. The potting compound is then preferably introduced to the edge 15 or to just below the edge 15, so that at least the connection elements 22a to 22e are covered with potting compound. The side legs of the core 16 are designated by the reference numerals 26 and 28 in FIG. 3 and the reference numeral 30 by the middle legs.

FIG. 4 shows a side view of the transformer 10 according to FIG. Like elements have the same reference numerals. In Figure 4 is further visible that on the bobbin 18, a second winding 21 is arranged. The winding 21 is a primary winding and the winding 20 is a secondary winding of the transformer 10.

FIG. 5 shows a sectional view of the transformer 10 according to FIG. 1 along the sectional plane AA. The upper yoke 34, which together with the side bars 26, 28 and the middle leg 30 forms a first E-shaped sheet metal part, contains recesses 36a, 36b, through which in an upper region of the bobbin 18 from the outer edge 38 of the bobbin 18 forth in the area the recess 36a, 36b a contact of the bobbin 18 is avoided with the core 16. In each case a recess 40a, 40b is formed in the side legs 26, 28, which adjoins the respective recess 36a, 36b in the yoke 34 in such a way that a common recess is formed around the outer walls 38 of the bobbin 18. In the central region of the side legs 26, 28, a further recess 42a, 42b is provided in each case, in the limiting elements 44a, 44b of the bobbin 18 protrude. Through the recesses 42a, 42b, a contact of these limiting elements 44a, 44b with the side legs 26, 28 prevented by the recess 42a, 42b. In the yoke 32 recesses 46 a, 46 b are provided which extend from the outer edge 48 of the bobbin 18 in the direction of the center leg 30 out, but do not extend to the center leg 30 out. Thus remain areas 50, 52 of the yoke 32, on which the bobbin 18 is seated and which is fixed by the position of the bobbin 18 with respect to the core 16. Further, laterally of the outer edge 48 in the side legs 26, 28 recesses 54a, 54b are provided similar to the recesses 40a, 40b, through which the outer edge 48 of the bobbin 18, the side legs 26, 28 and the yoke 32 is not touched.

In Figure 6, the detail Y of Figure 5 is shown in an enlarged view. Through the recesses 36b, 40b of the outer edge 38, the region of the bobbin 18 which is adjacent to the recesses 36b, 40b, insulated to the core 16, whereby a creepage distance between the primary winding 21 to the core 16 along the bobbin 18 has been considerably extended , The creepage distance between the primary winding 21 along the bobbin 18 to the core 16 is shown by the arrow P1.

The caused by the recesses 46b, 54b creepage distance at the lower outer edge 48 of the bobbin 18 between the secondary winding 22 and the core 16 is shown by the arrow P2. The sheet metal course according to DIN E130 is represented by the dash-dot-dot line 56. The recesses 36a, 36b, 40a, 40b, 42a, 42b, 46a, 46b, 54a, 54b thus cause an isolation of parts of the bobbin 18 relative to the core 16, whereby significantly longer creepage distances P1, P2 are present as without these recesses, thereby the way potential creepage flows have to travel is considerably prolonged. Possible creepage currents are considerably smaller or can be completely prevented. By the recesses 36a, 36b, 40a, 40b, 42a, 42b, 46a, 46b, 54a, 54b with respect to a metal sheet according to DIN creepage distances can be extended in a simple manner and cost-effective even with bobbins according to DIN. In particular, the fact that the recesses 36a, 36b, 46a, 46b are not guided to the central web 30, the bobbin 18 is fixed in its position.

In addition, the cavity formed by the recesses 36a, 36b, 40a, 40b, 42a, 42b, 46a, 46b, 54a, 54b around the coils 20, 21 or the bobbin 18 may be filled with potting compound so as to provide insulation between the coils 20, 21 and the core 16 to increase further. Preferably, the primary winding 21 is supplied with a nominal voltage of 230 V AC, depending on the ratio of the number of turns of the primary winding 21 to the secondary winding 20 in the secondary winding 20, a corresponding secondary voltage of, for example, 5, 12, 15, 24 and / or 30 V AC is induced.

FIG. 7 shows a sheet metal section of the transformer 10 according to FIG. 1 according to the invention. FIG. 8 shows the outline of the sheet-metal section according to FIG. 7 with a dimension, whereby the sheet-metal section of the transformer 10 moves from the sheet-metal section according to DIN according to FIGS. 1 and 2 in particular through the recesses 36a, 36b, 40a, 40b, 42a, 42b , 46a, 46b, 54a, 54b. Through these recesses, the air gaps between the windings 21, 20 and the core 16 are increased, so that the possibility of flashovers is reduced. Furthermore, a coating material can also be applied to the inside of the core, to the bobbin and / or the windings 20, 21 in an injection molding process, whereby the insulation is increased and the possibility of flashovers and leakage currents is reduced.

FIG. 9 shows a print transformer 60 according to a second embodiment of the invention. The transformer 60 is constructed similarly to the transformer 10 according to FIG. The transformers 10 and 60 differ in the shape of the respective sheet metal section, as will be explained in more detail below, in particular in connection with FIGS. 11 to 14. Like elements have the same reference numerals.

FIG. 10 shows a side view of the transformer 60 according to FIG.

FIG. 11 shows a sectional illustration of the transformer 60 according to FIG. 9 along the section line BB. 1, the side webs 62, 64 of the transformer 60 are narrower, so that in the longitudinal direction between the recesses 40a, 42a and 54a and between the recesses 40b, 42b and 54b remaining areas of the outer webs 26, 28 have been omitted in the embodiment of the transformer 60 with respect to the first embodiment of Figure 3, so that along the side webs 62, 64 in the region of the bobbin 18, a large recess is provided. As a result, the bobbin 18 touches the outer webs 62, 64 in any area. Recesses 68a, 68b are provided in the upper yoke 66 and have approximately the same dimensions as the recesses 72a, 72b provided in the lower yoke 70. With the help of the recesses 68a, 68b, 72a, 72b and by the distance between the side bars 62, 64 to the bobbin 18, the air gaps between the windings 20, 21 and the creepage distances between the windings 20, 21 to the core 74 along the bobbin 18th greatly increased, whereby leakage currents are at least reduced. In addition, the resulting space through the recesses can be filled with a potting compound and / or a Umspritzmaterial.

FIG. 12 shows the detail Z according to FIG. The dash-dot-dot line indicates in the same way as in Figure 6 the course of a sheet metal section according to DIN E130. By increasing the distance between the bobbin 18 and the side legs 64 and through the recesses 68a, 68b, 72a, 72b, the creepage distances between the primary winding 21 and the core 60 and between the secondary winding 20 and the core 16 are significantly increased, as by the Arrows P3 and P4 shown.

FIG. 13 shows the outline of a sheet metal layer of the layered core 74 of the transformer 60 according to FIG. This sheet metal layer is composed of a first sheet metal part 76 with an E-shaped basic shape and a second sheet metal part 78 with an I-shaped basic shape, wherein a plurality of first sheet metal parts 76 are stacked to a first core element and interconnected and preferably the same number of second sheet metal parts 78 superimposed and are connected to each other, wherein the first sheet stack and the second sheet stacks are joined together only after the bobbin 18 has been pushed onto the center leg 30.

FIG. 14 shows the outline of the sheet-metal section according to FIG. 13 with dimensioning.

The blanks used in transformers 10 and 60 have the same external dimensions as the blanks specified in the El30 DIN. Also, the width of the central web 30 and the distance between the two opposing yokes in the adjacent to the central web 30 areas 50, 52 corresponds to the distance of the yokes of the EI30 DIN. As a result, it is also possible to use standard coil bodies in the sheet metal sections according to the invention, as they are also used in sheet metal sections according to EI30 DIN. The transformers 10 and 30 may also have a higher secondary voltage than primary voltage in alternative embodiments. The side legs of the core are generally referred to as outer leg and the recesses also as recesses.

Although in the drawings and the foregoing description preferred embodiments have been shown and described in detail, this should be considered as illustrative and not restrictive of the application. It should be understood that only the preferred embodiments have been illustrated and described, and all changes and modifications that are presently and in the future within the scope of the invention should be protected.

LIST OF REFERENCE NUMBERS

10, 60

PCB transformer

12

shell

14a to 14d

connector pin

15

lower edge

16, 74

core

18

bobbins

20, 21

winding

22a to 22d

connection elements

24

carrier

26, 28, 62, 64

side leg

30

middle leg

32,34,66,70

yoke

36a, 36b, 40a, 40b, 42a,

42b, 46a, 46b, 54a, 54b,

68a, 68b, 72a, 72b

recesses

44a, 44b

Projection in the bobbin

48

outer edge

50, 52

head Start

P1 to P4

creepage

76

first sheet metal part

78

second sheet metal part

Claims (13)

Sheet metal cut for a layered core of a transformer
a first sheet metal part having an E-shaped basic shape and forming a first yoke, two outer legs and a middle leg of a layer of the core,
with a second sheet metal part having a 1-shaped basic shape and forming a second yoke of the layer of the core,
wherein in the assembled state of the first and second sheet metal parts the free ends of the legs of the first sheet metal part abut against a longitudinal side of the yoke of the second sheet metal part, so that two windows are formed with a rectangular basic shape bounded by the legs and yokes,
characterized in that at least in the first yoke and in the second yoke at least one recess is provided in a portion of each of the windows, by which the area of the windows is increased in each case. Sheet metal section according to claim 1, characterized in that the recesses in the yokes adjacent to the respective adjacent outer legs and extending in the direction of the center leg, and that coil windings are preferably arranged around the center leg around. Sheet metal section according to claim 2, characterized in that at least one further recess is provided in each of the side legs on the side facing the respective window, wherein preferably at least two recesses are provided in each of the side legs of where a first recess adjacent to a respective recess in the first yoke and the second recess adjacent to a respective recess in the second yoke, so that in the two adjoining the outer leg corners of the window in each case a common recess is formed. Sheet metal section according to claim 3, characterized in that in each case in an area between the two recesses, at least one third recess in the outer legs is provided on its side facing the window. Sheet metal section according to one of the preceding claims, characterized in that at least the recesses provided in the yokes have a length along the window width in the range of 30% to 95%, preferably in the range of 40% to 60%, in particular 50%, of the window width , Sheet-metal section according to claim 3, characterized in that at least the two recesses provided in the legs facing the windows have a length along the longitudinal axis of the leg in the range of 30% to 95%, preferably in the range of 40% to 60%, in particular 50%. have the window width. Sheet metal section according to claim, characterized in that third recess has a length along the side facing the window of the respective leg in the range of 100% to 300%, preferably 150% to 250% of the length of the first and / or the second recess. Sheet metal section according to one of the preceding claims, characterized in that the recesses in the first yoke have the same length and that the recesses in the second yoke have the same length. Sheet metal section according to one of the preceding claims, characterized in that the recesses in the first yoke are each shorter than the recesses in the second yoke. Sheet metal section according to one of the preceding claims, characterized in that all the recesses are arranged mirror-symmetrically to the central axis of the central web. Sheet metal section according to one of the preceding claims, characterized in that the recesses form a cavity around at least one region of the bobbin. Sheet metal section according to one of the preceding claims, characterized in that the sheet metal layer is a sheet metal layer of a layered core of a transformer. Sheet metal section according to one of the preceding claims, characterized in that the recesses have a substantially rectangular basic shape, wherein at least two inner corners of a recess provided in the legs and / or yokes are preferably formed as a circular arc.

Images