FR2684484A1 - Coil for a transformer - Google Patents

Abstract

This is a coil for a power transformer in switched mode, comprising coil former elements which can be nested together (10, 18, 20) each incorporating barriers (14, 16, 22, 24) respectively supplying 3 and 6 mm leakage paths, the windings extending over the complete width (W) between the barriers and the elements nesting together above an inter-winding strip applied over the whole width (T) of the elements comprising the leakage barriers.

Description

COIL FOR TRANSFORMER

  The invention relates to a support coil for winding windings or windings of a transformer, and more particularly of a power supply transformer in switch mode (Switch Mode Power Supply in

  Anglo-Saxon SMPS terminology for short).

  With this type of transformer, we currently use coils segmented either vertically or horizontally to support

  primary and secondary windings.

  Figure 1 of the attached drawings shows the principle of a vertically segmented coil, in which the layers of primary and secondary turns are respectively designated by the references "P" and "S" The disadvantage of this type of arrangement is that the inductance leakage values are much too high to allow the use of such a transformer at

very high frequencies.

  FIG. 2 shows the principle of a horizontally segmented coil, suitable for a "SMPS" type transformer intended to be used at high frequencies. The layers of primary (P) and secondary (S) turns are separated by an insulating strip, and inserted barriers, producing elongated escape routes, are also

incorporated into the coil.

  The disadvantage of this type of arrangement is that, if the leakage barriers are formed by layers of tape enveloping the coil, the production takes time, is costly and difficult to automate. Alternatively, if the barriers are formed from elements made of molded insulating material, they are then difficult to hold in place and then generate serious handling problems In addition, the leakage barriers being added to the thickness of the end wall of the coil, this results in a loss of theoretically available space for windings. The object of the invention is to provide a transformer coil which has a low leakage like that obtained with horizontally fragmented windings, while making it possible to overcome the

  production problems described above.

  According to the invention, a transformer coil is notably proposed comprising several elements of nestable coil skeletons, each element incorporating a first and a second

spaced leakage barriers.

  In an advantageous embodiment, the windings extend over the entire width of the space between the first and second barriers, an inter-winding strip is applied over the entire width of these elements including the barriers, and skeleton elements

  of the coil fit onto the inter-

winding applied.

  The coil elements preferably include an internal coil element with ends integral with said internal coil element and at least one element

external coil skeleton.

  The outer coil skeleton element can advantageously incorporate conductive wire guide pins, allowing the output end of the wire to be brought through the winding and terminated Slots in the skeleton element spool allow the output end of the wire to exit the spool at different angles, reducing crossover

the outlet end of the wire.

  The coil elements are preferably provided with ratchet-type parts, which fix the coil elements nested together in a

assembly fixed together.

  Advantageously, the assembled coil as described complies with IEC 65 (International Electrotechnical Commission) which specifies a 6 mm leak path plus 0.4 mm distance through the insulation (or three layers of insulating material ) between the input and output windings, but the principle can be applied to

  any dimension of an extended escape route.

  Anyway, and according to another embodiment of the invention, this does not mean that a barrier of 6 mm must be provided all around the coil When there is no output which crosses the barrier, a barrier of 3 mm wide can be provided and provide a 6 mm leakage passage According to this additional characteristic of an embodiment of the invention, a barrier of 3 mm is provided all around the coil to the except for the exit position, where the barrier passes to a width of 6 mm In this way, an additional winding width of 3 mm is created in a reel of dimensions outside

all identical.

  The constitution of the coil described above has several advantages, namely: as two leakage barriers are molded as part of a common element, they are easier to handle and are held more securely in the correct position; then the barrier forms the end wall of the coil, which thus makes more efficient use of the available winding space; thirdly, not only is the low leakage of the horizontally segmented windings maintained, but the winding width being increased, this further reduces the leakage; fourth, as explained above, wide guide slots and protrusions will be able

be easily incorporated.

  A transformer coil according to the invention will now be described by way of example with reference to the accompanying drawings, in which: Figures 1 and 2 show the prior art; FIG. 3 shows a coil construction (for a "SMPS" transformer) according to an embodiment of the invention; Figures 4 A and 4 B are explanatory diagrams; and Figure 5 shows another embodiment of a coil skeleton element according to the invention. Referring to Figure 3, a "SMPS" transformer coil includes an internal coil element 10 having ends integral with the coil 12 The coil element 10 has a leakage barrier 14 of 6 mm at one end and a leakage barrier 16 of 3 mm at the other end. The reel also comprises elements of a coil skeleton interlocking 18 and 20, the element 18 being arranged to nestle or interlock above the internal reel element 10 and the element 20 to nestle or nest over element 18, as shown

  by the broken lines in the drawing.

  The coil skeleton elements 18 and 20 are generally similar and each incorporates a 6 mm leak barrier 22 at one end and a

  leakage barrier 24 of 3 mm at the other end.

  The barriers 22, 24 are connected on their opposite sides by partial side walls 26, 28, at least one of these walls being equipped with wire guide pins forming an integral part, or with projections 30 The slots wide 32 between the partial side partial walls 26, 28 make the exit of the connection ends possible from the coil with different angles Ratchet-type formations 34, 36, formed integrally with the elements make it possible to fix said elements Between

them in the assembled condition.

  In the assembled coil, the windings (not shown) o each coil element extends over the total width W between the first and second

  barriers 22, 24 while the strip inter-

  winding is applied over the total width T of the coil element, including the leakage barriers The coil elements 10, 18, 20 are thus arranged to fit above the strip

applied inter-winding.

  As shown in Figure 4 A, a 6 mm escape route is possible with a 3 mm wide barrier provided that no wire outlet crosses the

barrier at this point.

  Anyway, when an outlet actually crosses the barrier, as shown in Figure 4B, it is necessary to provide a barrier

6 mm wide.

  According to an embodiment of the invention, shown in FIG. 5, the nestable coil elements described above are supplied with a barrier 38 of 3 mm, in place of a barrier of 6 mm, with the exception of the exit position 40, where the

  barrier has a portion 42 of increased width by 6 mm.

  This creates an additional width of 3 mm.

  As it goes without saying, and as it follows from the above, the invention is not limited to the embodiments more particularly described here. On the contrary, it embraces all the variants falling within it.

equivalence framework.

Claims (6)

  1 transformer coil, in particular SMPS type transformer, comprising several nestable coil skeleton elements (10, 18,), each incorporating first and second   leakage barriers (14, 16, 22, 24) spaced apart.   2 coil according to claim 1 characterized in that the required escape route is provided directly by the first barrier and indirectly by the second.   3 coil according to claim 1 or claim 2 characterized in that the windings extend over the total width (W) of the space between the first and second barriers, an inter-winding strip is applied over the total width (T ) elements including the barriers, and the elements of the coil skeleton fitting together above the applied inter-winding strip. 4 Coil according to any one of   claims 1 to 3 characterized in that the   coil elements include an internal coil element with ends integral with said element and at least one coil element external coil.   Coil according to claim 4, characterized in that the external coil element is formed with protuberances or spikes   integral (30) with said element for the exit of the wire.   6 coil according to claim 4, characterized in that the outer coil element is formed with wide slots (32) allowing the   wire exit at different angles. 7 Coil according to any one of   claims 1 to 6, characterized in that the   coil elements are provided with pawl type functions (34, 36), integral with said elements for fixing said elements fitted together. 8 coil according to claim 2 or one   any of the dependent claims of the   claim 2, characterized in that the coil elements each have leakage barriers entirely around the element.   9 coil according to claim 3, characterized in that the width of each leak barrier is equal to half a leak path   or the entire escape route.   Coil according to claim 2 or one   any of the dependent claims of the   claim 2, characterized in that the coil elements each have a first and second leakage barriers of equal width except at the exit position, where the width is increased to double that of the first and second leakage barriers.