EP0836205B1 - Winding method of turns in radial layers - Google Patents

Description

The present invention relates to the production of a electric coil whose layers of turns are radial and alternately wound from the inside to the outside and from outside to inside. Such a coil is described in DE-A-12 39 016.

When such coils are used in high voltage applications, for example in transformers, they have the advantage of not requiring any insulation between layers of turns. This is achieved due to the fact that two adjacent turns of two successive layers are not separated only by a small number of turns, so that they are subject to a relatively low potential difference does not requiring the interposition of an insulation between the two layers.

An object of the present invention is to provide a method of winding such radial layer coils, which is particularly simple to implement.

Another object of the present invention is to provide such a process which allows, using a single device, make coils of variable internal and external diameters.

These objects are achieved according to the invention thanks to a winding process of coils in wound radial layers alternately from outside to inside and from inside outwards. To wind a layer from the outside to inside, the process includes the steps of forming around a core the layer with an internal diameter greater than diameter of the core, and to exert a traction on the internal whorl to tighten the layer on the core.

According to an embodiment of the present invention, the layer is formed by exerting an axial pressure on the turns during their winding.

According to an embodiment of the present invention, the method further comprises the steps of winding directly around the core the next layer from the inside outward by pressing on the exposed side of this layer; to axially offset the layers by the thickness of two layers; maintain the last layer on the periphery providing a support plan for a new layer; and to realize the new layer wound from the outside to the inside.

The present invention also relates to an apparatus for implementing the above-mentioned method, comprising a crown radial surrounding the nucleus and defining with it a space winding a current layer; radial rollers extending to the core and urged towards the upper face of the crown; radial wedges movable between a position in contact with the core and a retracted position, these shims being shifted down from the top of the crown of a distance between a layer thickness and two layer thicknesses; and means for lifting the crown compared to the core of two layer thicknesses.

According to an embodiment of the present invention, the crown has retractable platforms associated with rollers to allow the rollers to lower.

According to an embodiment of the present invention, the apparatus includes a wire feeder for supplying the turns during winding at one of the rollers, the debtor being capable of selectively exerting traction or axial pressure on the wire.

According to an embodiment of the present invention, the rollers are conical, their largest diameter being side of the nucleus.

According to an embodiment of the present invention, the rollers are fixed and the whole of the crown, shims and the nucleus is rotating.

la figure 1 représente une vue de dessus d'un mode de réalisation d'appareil de bobinage permettant de mettre en oeuvre le procédé de bobinage selon l'invention ; et

les figures 2A à 2F représentent une vue de côté partielle en coupe de l'appareil de la figure 1, à des étapes successives du procédé de bobinage selon l'invention.

These objects, characteristics and advantages, as well as others of the present invention will be explained in detail in the following description of particular embodiments given without limitation in relation to the attached figures among which:

Figure 1 shows a top view of an embodiment of the winding apparatus for implementing the winding method according to the invention; and

FIGS. 2A to 2F represent a partial side view in section of the apparatus of FIG. 1, at successive stages of the winding method according to the invention.

An essential aspect of the winding process according to the invention lies in the production of the wound layers of outside to inside. To make such a layer according to the invention, we start by winding it from the outside towards the interior from an outside diameter greater than outer diameter of the future coil. This is achieved advantageously by exerting an axial pressure on the turn in winding course, so that the entire layer has tendency to get bigger. Once the number of turns of the layer has been reached, the inner diameter of the layer is inevitably larger than the diameter of the nucleus of the future coil. So, we pull the last turn, that is to say the inner coil, to tighten the whole of the layer on the core, this core can be of section and any diameter.

Figures 1 and 2A show a top view and a partial side view in section of an embodiment winding apparatus for carrying out the method according to the invention. The core 10 of the future coil is arranged substantially in the center of a radial crown 12. The space between the core 10 and this crown 12 is intended to receive a layer 14 during winding. The internal diameter of the crown therefore determines the maximum external diameter of the coil.

The upper face of layer 14 is held in place by radial rollers 16 (of which only three are shown) which are biased towards the upper face of the crown 12 and come into contact with the core 10. These rollers 16 slide axially in order to be able to modify the diameter of the core 10. The winding wire 14-1 comes tangentially from below one of the rollers 16. To facilitate the introduction of wire 14-1, we can provide an area without rollers in front of the roller which receives the wire.

The underside of layer 14 is held in place by radial wedges 18 regularly distributed around the core 10 below the crown 12. Each of these wedges 18 is movable between a position of contact with the core 10 and a position retracted where the inner end of the wedge is located substantially at the level of the internal diameter of the crown 12. The stroke of these shims 18 and of the rollers 16 determines the minimum core diameter 10.

The assembly of the crown 12, the core 10, and the shims 18 is likely to be rotated about the axis of the core while the rollers 16 are fixed. As is shown, the rollers 16 are preferably conical, the most large diameter being on the side of the core 10. The rollers 16 are then tilted to provide a horizontal plane to maintain the wound layer 14. As a result, the contact zone between each roller 16 and the core 10 is reduced to a point, which reduces friction.

The crown 12 includes platforms 20 which can be brought into correspondence with the rollers 16 by a rotation of the crown 12. These platforms 20 are retractable down to allow the rollers 16 to lower to reach the plane of the holds 18.

As shown by way of example, the wire 14-1 is rectangular or square. We would prefer such a choice, because it facilitates the adjustment of the device according to the section of the thread. The distance between the rollers 16 and the shims 18 can then be freely adjusted between once and twice the wire height. It is thus possible, with a single adjustment, to wind wires varying in height from single or double.

If the wire is of circular section, the height of the shims 18 must be adjusted so that the distance separating them rollers 16 is substantially equal to the diameter of the wire, this to prevent the turns of the same layer from overlapping. To facilitate the winding of a wire with circular section, we prefer to laminate the wire so that it has flats parallel to the winding axis, which will prevent the overlap.

Figures 1 and 2A illustrate a first step in winding of a first layer from the outside to the inside. The rollers 16 are in contact with the upper face of the crown 12 and the shims 18 are supported on the core 10. The crown 12 (as well as the shims 18 and the core 10) is set clockwise rotation, for example. A debtor, no shown, provides wire 14-1 with some axial pressure P in the direction of rotation of the crown 12. This pressure P is chosen so that the turns being wound have tends to move away from the nucleus 10. Thus, the first turn has tendency to press against the internal diameter of the crown 12 and each subsequent turn tends, as is shown, to be pressed inside the previous turn.

When the desired number of turns is reached, the layer that we just wound normally has a diameter internal greater than the diameter of the nucleus.

The next step, illustrated in Figure 2B, is to pull T on wire 14-1 until the layer which has just been wound up tightens on the core 10. This traction T is preferably exerted by stopping the crown 12 and operating the debtor in reverse. According to one variant, traction T could be obtained by braking the debtor while the crown 12 continues to rotate.

As shown in Figures 2A and 2B, if the distance between the rollers 16 and the shims 18 is greater than the height of the wire, the turns that are obtained are generally not not in the same plane. This is not annoying, as we will see below.

In FIG. 2C, the layer which has just been wound with the outside towards the inside has just been tightened around the core 10 and the crown 12 rotates clockwise. The whorl during winding 14-1, for lack of space, climbs on the last internal turn of the layer we just wound and lifts the rollers 16. Indeed, these rollers 16 slide vertically and are biased down elastically or simply by gravity. Thus, the turn being wound and the coil which is immediately below are forced towards the shims 18 under the pressure exerted by the rollers 16. The successive turns will wind from the inside towards the outside while aligning the turns of the previous layer.

In Figure 2D, the number of turns desired for the second layer is reached. As shown, the two layers that we just wound are perfectly flat.

In FIG. 2E, the crown 12 performs, if necessary if necessary, a fraction of a turn to bring platforms 20 into correspondence with the rollers 16. So the platforms 20 are lowered while the wedges 18 are retracted. In practical, the layers we just wound are so tight on core 10 that they cannot slide down under the force of the rollers 16. Furthermore, this sliding is not desirable because it could damage the insulation of the turns interior. On the other hand, the crown 12 is offset relative to the core 10 the height of two layers, as shown. For this, the crown 12 is lifted, for example, by a jack with position adjustable by digital control. Alternatively, the core 10 could be lowered, which would however disadvantage of doubling the overall height of the device the fact that the core 10 should move to one side and the other from crown 12.

In FIG. 2F, the shims 18 are slid towards the core 10 and the platforms 20 are then lifted to their initial position. The internal ends of the shims 18 come abut against the outer coil of the last wound layer and maintain this layer which would otherwise tend to unfold.

The device is then ready to repeat the step illustrated in Figure 2A to wind a new layer of outside to inside.

Each layer can be made to a diameter different. This possibility has the advantage of allowing the creation of intermediate output terminals for which the total number of turns is not a multiple of the number of turns nominal layers.

To allow the realization of a diameter layer lower than that of the previous layer at the step of FIG. 2D, the thickness of the shims 18 is chosen to be less than the thickness of the layers. So the holds can still reach the outside diameter of this layer at the Figure 2F.

According to an advantageous variant (not shown) of the device, the crown 12 is continuous, that is to say devoid of retractable wedges 20. So, to go from the stage of the Figure 2D to that of Figure 2E, a set of pressers is provided which press on the new layer wound in the defined space between the rollers 16, the core 10, and the internal diameter of the crown 12. These pressers descend at the same time as the rollers and continue to descend when rollers 16 abut on the upper face of the crown 12, to bring the last layer wound at the level of the radial shims 18 in FIG. 2E.

The translational displacements of the various elements of the apparatus, except of the core 10, are ensured by jacks tires, for example. The rotation can be ensured by a DC motor.

In the above description, it has been assumed as example that the core 10 was of circular section. he can of course be of any section.

Many variations and modifications to this invention will appear to those skilled in the art. For example, we can wind several wires at the same time.

Claims (8)

1. A method for achieving windings in radial layers alternately wound from the outside to the inside and from the inside to the outside, characterized in that it includes, for winding a layer from the outside to the inside, the steps of:

   forming around a core (10) the layer (14) with an internal diameter greater than the core diameter; and

   exerting a traction (T) on the internal winding to tighten the layer on the core.
2. The winding method of claim 1, characterized in that the layer is formed by exerting an axial pressure (P) on the windings (14-1) while they are wound.
3. The winding method of claim 1 or 2, characterized in that it further includes the steps of:

   winding directly around the core (10) the next layer from the inside to the outside while exerting a pressure on the exposed surface of this layer;

   axially shifting the layers by the thickness of two layers;

   maintaining at the periphery the last layer by providing a supporting plane to a new layer; and

   making the new layer wound from the outside to the inside.
4. An apparatus for carrying out the winding method of any of claims 1 to 3, characterized in that it includes:

   a radial ring (12) surrounding the core (10) and defining therewith a winding space for a current layer (14);

   radial rollers (16) extending to the core and urged towards the upper surface of the ring;

   radial shims (18) movable between a position in contact with the core and a retracted position, these shims being shifted down with respect to the upper surface of the ring by a distance comprised between one layer thickness and two layer thicknesses; and

   means for raising the ring with respect to the core by two layer thicknesses.
5. The apparatus of claim 4, characterized in that the ring (12) includes retractable platforms (20) associated with the rollers (16) to enable the rollers to be lowered.
6. The apparatus of claim 4 or 5, characterized in that it includes a wire supply for supplying the currently wound windings at the level of one of the rollers (16), the wire supply being adapted to selectively exert a traction or an axial pressure on the wire.
7. The apparatus of any of claims 4 to 6, characterized in that the rollers (16) are cone-shaped, their greater diameter being on the core side.
8. The apparatus of any of claims 4 to 7, characterized in that the rollers (16) are fixed and the ring (12), shims (18) and core (10) all rotate.

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