WO2017093096A1

WO2017093096A1 - Insulating tape for electrical components

Info

Publication number: WO2017093096A1
Application number: PCT/EP2016/078542
Authority: WO
Inventors: Valentino RADAELLI
Original assignee: Itacoil S.R.L.
Priority date: 2015-12-02
Filing date: 2016-11-23
Publication date: 2017-06-08
Also published as: ITUB20156089A1

Abstract

An insulating tape (10, 10', 10'') apt to be wound around conducting elements of electrical components, capable of increasing the clearance and creepage distances between conducting elements, comprises a flat central portion (11), lying in a plane (α), and at least one edge portion (12A, 12B) contiguous to the flat central portion (11) along a longitudinal unwinding direction of the insulating tape (10, 10', 10''), such at least one edge portion (12A, 12B) having a ripple (OND) with respect to theplane (α) of the flat central portion (11).

Description

Title: Insulating tape for electrical components

DESCRIPTION

Application field

The present invention pertains to the technical field of insulating tapes for electrical components, in particular for electrical components comprising electrical windings, and the following description is made with reference to this application field with the only purpose of simplifying the exposition.

Prior art

As it is well known in this specific technical field, in order to ensure the electrical insulation between two conducting elements, such as the primary winding and the secondary winding of a transformer, a mono- or multilayer insulating tape is interposed therebetween.

When providing such an electrical insulation, it is important to ensure an appropriate clearance and creepage distance between the conducting elements.

Generally, the clearance distance is defined as the shortest distance measured in air between two conducting elements, whereas the creepage distance is defined as the shortest distance measured on the surface of the insulating material between the two conducting elements. In particular, specific regulatory and functional requirements impose a minimum clearance distance and creepage distance which are to be ensured by the insulating tapes between the conducting elements of an electrical component according to the applications, in order to prevent electrical discharges from being generated between such conducting elements.

In the past, the prior art offered some solutions aimed at increasing the clearance and creepage distances between conducting elements in an electrical component.

For example, in a first known solution, depicted in Figures 1A and IB, the use of a fringed insulating tape 1 is provided, the tape comprising a plurality of cuts T at the edge portions 2 A and 2B thereof. Thereby, as shown in Figure IB, when such a fringed insulating tape 1 is used to electrically insulate an electrical winding 3 arranged on a spool 4, it allows to achieve a greater clearance and creepage distance between the insulated conducting elements as compared to the normal flat tapes that do not comprise the plurality of cuts T at the edge portions, especially allowing to partially cover the walls of the spool 4 at the end portions 3A and 3B of the electrical winding 3 by bending the edge portions 2A and 2B of the fringed insulating tape 1. Although advantageous in several aspects, this first solution has several drawbacks, in particular a poor electrical insulation when using a single layer of the fringed insulating tape 1 due to the presence of the cuts T of the edge portions 2A and 2B thereof, which result in physical interruptions of the edge portions 2A and 2B themselves, at which interruptions the current is allowed to pass. This generally implies the need to apply three or four layers of the fringed insulating tape 1 even where smaller insulation thicknesses prove to be sufficient, thus reducing the performance of an electrical component comprising such superimposed fringed insulating tapes 1. Therefore, the clearance and creepage distances actually obtained by means of the fringed insulating tape 1 can vary as a function of the number of superimposed layers and of the random relative positioning of the cuts T in each superimposed layer. Moreover, applying this technique to adhesive and/ or thin insulating tapes is technically difficult. Furthermore, an insulating tape is known from German patent published with number DE 102 33 334 to Frank, the tape having an accordion-like shape and thus being shaped so that several layers of such an insulating tape are superimposed. In particular, such an accordion-like pattern is realized over the whole length of the tape, where length means the tape dimension in the direction orthogonal to the longitudinal direction (i.e. orthogonal to the unwinding direction thereof).

Although serving its purpose, this known solution is not free from drawbacks, because it results in higher costs and laboriousness, as well as in possible minimum thicknesses of the tape multiplied at least three times with respect to the thickness of the basic tape, thus excluding the possibility of manufacturing tapes of small thicknesses.

The Chinese utility model published with number CN202258735 to Mou et al. further describes a multilayer insulating tape, comprising a first adhesive layer, a second adhesive layer, and a crepe layer interposed between the first and second adhesive layers.

Although advantageous in several aspects, also this known solution has several drawbacks, especially related to costs and high thickness of such a multilayer insulating tape.

Furthermore, the European patent application published with number EP 0 724 765 to Christensen suggests an insulating tape for transformers, which is shaped with a cylindrical profile and then deformed to have a substantially U-shaped section, such a tape completely covering a first face of an electrical winding of a transformer and further having end portions capable of being bended so as to cover both the edges and, at least partially, a second face of the electrical winding.

However, the aforementioned known solution results in high costs and processing difficulties, in addition not allowing using inexpensive and/ or thin insulating tapes, such a solution being appreciable only in a few applications where the voltages involved are very high. Finally, a last widespread known technical solution is illustrated in Figure 2A, which schematically shows a section view of an electrical component comprising a spool 5, a first electrical winding 6 directly wound on the body of the spool 5, and a second electrical winding 7. In such a known solution, increased clearance and creepage distances between the electrical windings 6 and 7 are achieved by forming steps made of insulating material 8 on the spool 5, which steps are in contact with the edges of the first electrical winding 6, thus creating a barrier of insulating material directly on the body of the spool 5. A layer of flat insulating material 9 is finally arranged between the first electrical winding 6 and the second electrical winding 7. In other words, in the body of the spool 5, substantially T-shaped seats are defined, which house the first electrical winding 6 and the second electrical winding 7.

Alternatively, as depicted in Figure 2B, instead of the steps made of insulating material 8, a plurality of layers of adhesive insulating material 8' is arranged on the walls of the spool 5, the layers being in contact with the edges of both the electrical windings 6 and 7, which are spaced apart by the flat insulating tape 9. This last solution also has some drawbacks, because the overall dimension of the steps made of insulating material 8 or of the layers of adhesive insulating material 8' is such that the performance of an electrical component adopting such a solution is strongly reduced.

The technical problem of the present invention is to provide an insulating tape for electrical components, the tape having structural and functional features such as to allow overcoming the limitations and drawbacks still affecting the known solutions, in particular capable of allowing to increase the clearance and creepage distances between conducting elements of electrical components in a simple manner, without compromising the performance of the electrical components, allowing at the same time to decrease the manufacturing costs.

Summary of the invention

The solution idea underlying the present invention is to provide an insulating tape for electrical components having at least one edge portion provided with a ripple capable of adapting to the shape of a housing or of a support of an electrical component where the tape is used, so as to increase the clearance and creepage distances between conducting elements, in particular between electrical windings, of such an electrical component. Based on of this solution idea, the technical problem is solved by an insulating tape apt to be wound around conducting elements of electrical components, the insulating tape comprising a flat central portion, lying in a plane, and at least one edge portion contiguous to the flat central portion along a longitudinal unwinding direction of that insulating tape, characterized in that the at least one edge portion has a ripple with respect to the plane of the flat central portion.

More particularly, the invention comprises the following additional characteristics, taken individually or in combination if required. First, it is worth noting that the at least one edge portion may be plastically deformed at the ripple.

Moreover, the insulating tape according to the present invention may comprise respective edge portions arranged on opposite sides of the flat central portion and contiguous thereto along a longitudinal unwinding direction of the insulating tape, both those edge portions having a ripple.

In particular, the insulating tape may be made of an adhesive dielectric material or may comprise a multilayer structure including a superposition of different dielectric material layers. According to an aspect of the invention, the ripple of the at least one edge portion may be distributed in a continuous manner along the at least one edge portion. Alternatively, the ripple of the at least one edge portion may be distributed in a discontinuous manner along the at least one edge portion. Moreover, an electrical component is described, comprising at least one conducting element, wherein the at least one conducting element is insulated by means of an insulating tape according to the present invention.

In particular, the at least one conducting element may be an electrical winding and the electrical component may be selected from a transformer and a coupled inductor.

The invention also refers to a method for manufacturing an insulating tape apt to be wound around conducting elements of electrical components, the insulating tape comprising a flat central portion, lying in a plane, and at least one edge portion contiguous to the flat central portion along a longitudinal unwinding direction of that insulating tape, the method advantageously comprising the steps of:

- providing the insulating tape to a forming device comprising at least one pair of toothed wheels, the at least one pair of toothed wheels being provided with a plurality of teeth that are mutually engaged, the insulating tape being provided so that the at least one edge portion is trapped at the plurality of mutually engaged teeth; - rotating the at least one pair of toothed wheels, so that the at least one edge portion is pulled through the plurality of mutually engaged teeth; and

- forming by stretching the at least one edge portion by means of the plurality of teeth of the at least one pair of toothed wheels, by impressing a ripple to the at least one edge portion with respect to the plane of the flat central portion.

In particular, the forming device may comprise a first pair of toothed wheels and a second pair of toothed wheels, the first pair of toothed wheels and the second pair of toothed wheels being provided with respective plurality of teeth that are mutually engaged, the plurality of teeth impressing the ripple to respective edge portions of the insulating tape, the respective edge portions being arranged on opposite sides of the flat central portion and contiguous thereto along a longitudinal unwinding direction of the insulating tape.

Moreover, the at least one pair of toothed wheels of the forming device may comprise a plurality of teeth distributed in a discontinuous manner, so that the step of forming by stretching impresses a ripple on the at least one edge portion of the insulating tape, that ripple being distributed in a discontinuous manner along the at least one edge portion.

Finally, the step of rotating may comprise a cadenced distancing of a toothed wheel of the at least one pair of toothed wheels with respect to the other toothed wheel, so that the step of forming by stretching impresses a ripple on the at least one edge portion of the insulating tape, the ripple being distributed in a discontinuous manner along the at least one edge portion, the cadenced distancing being changed according to specific needs.

The features and advantages of the insulating tape according to the invention will become apparent from the following description of an embodiment thereof, given by way of non-limiting example with reference to the accompanying drawings. Brief description of the drawings

In those drawings:

- Figure 1A shows a schematic view of a fringed insulating tape manufactured according to the prior art; - Figure IB shows a perspective view of an electrical component where the insulation between electrical windings is achieved by means of the fringed insulating tape of Figure 1A;

- Figure 2A shows a schematic sectional view of an electrical component where the insulation between electrical windings is achieved according to the prior art;

- Figure 2B shows a schematic sectional view of an electrical component where the insulation between electrical windings is achieved according to a variant of the technique shown in Figure 2A;

- Figure 3 shows a schematic view of an insulating tape according to the present invention;

- Figure 4A shows a perspective view of an electrical component where the insulation between electrical windings is achieved by means of the insulating tape of Figure 3;

- Figure 4B shows a perspective view of an electrical component where the insulation between electrical windings is achieved by means of the insulating tape of Figure 3 and where a spool has flanges with a wall interruption;

- Figure 5 shows a schematic sectional view of an electrical component where the insulation between electrical windings is achieved by means of the insulating tape of Figure 3;

- Figure 6 shows a perspective view of an electrical component where the insulation between electrical windings is achieved by an insulating tape according to an alternative embodiment of the present invention;

- Figure 7 shows a perspective view of an electrical component where the insulation between electrical windings is achieved by an insulating tape according to a further alternative embodiment of the present invention;

- Figure 8A shows a schematic view of an insulating tape manufactured by means of a method according to the present invention; and

- Figure 8B shows a schematic view of an insulating tape manufactured by means of a variant of the method according to the present invention.

Detailed description

With reference to those figures, and in particular to Figure 3, an insulating tape for electrical components manufactured according to the present invention is globally and schematically indicated with 10. It is worth noting that the figures represent schematic views and are not drawn to scale, but instead they are drawn so as to emphasize the important features of the invention. Moreover, in the figures, the different elements are depicted in a schematic manner, their shape varying depending on the application desired. Finally, it is noted that in the figures the same reference numbers refer to elements that are identical in shape or function.

In its most general aspect, the insulating tape 10 for electrical components according to the invention comprises a substantially flat central portion and at least one edge portion contiguous thereto along a longitudinal (unwinding) direction of such an insulating tape 10. Suitably, such at least one edge portion is provided with a ripple with respect to a plane of the flat central portion.

In particular, in the example of Figure 3, the insulating tape 10 for electrical components is depicted rectilinearly extending and comprises a substantially flat central portion 1 1 , lying in a plane a, a first edge portion 12A and a second edge portion 12B, such respective edge portions 12A and 12B being arranged on opposite sides of that flat central portion 1 1 and being contiguous thereto along a longitudinal (unwinding) direction of the insulating tape 10. The insulating tape 10 is adapted to electrically insulate conducting elements of an electrical component, e.g. is adapted to be wound on electrical windings of a transformer or of an inductor.

Advantageously according to the present invention, at least one of the first edge portion 12 A and the second edge portion 12B of the insulating tape 10 has a ripple OND with respect to the plane a of the flat central portion 1 1. In particular, the ripple OND of the at least one edge portion 12A or 12B is a permanent ripple. In a preferred embodiment, such a permanent ripple is obtained by plastically deforming the at least one edge portion 12A or 12B.

In this way, the insulating tape 10 according to the present invention has at least one of the first edge portion 12A and the second edge portion 12B that is plastically deformed at the ripple OND. More specifically, such at least one plastically deformed edge portion 12A or 12B has a profile having a greater length than the flat central portion 1 1 , such a length being measured along the longitudinal (unwinding) direction of the insulating tape 10 when that at least one edge portion 12A or 12B is made rectilinear. Here and below, the term ripple refers to a surface irregularity, such as for example a plastic deformation. More particularly, in the example shown in Figure 3, the ripple OND is substantially periodic and is characterized by a predetermined pattern, a predetermined pitch X, and a predetermined width A. Again with reference to Figure 3, a preferred embodiment of the insulating tape 10 is shown, wherein the ripple has a substantially sinusoidal pattern, but the invention is not limited thereto, since the ripple may have any other pattern, for example the ripple may have a saw-tooth pattern.

Moreover, in the embodiment shown in Figure 3, both the edge portions 12A and 12B have a ripple.

The ripple OND of the edge portions 12A and 12B has a predetermined pitch X, generally in the range from 0.3 mm to 4 mm. In a preferred embodiment, the pitch X is in the range from 0.8 mm to 1.5 mm.

Furthermore, the ripple OND of the edge portions 12A and 12B has a predetermined width A, generally from 0.2 mm to 2.5 mm. In a preferred embodiment, the width A is in the range from 0.4 mm to 0.9 mm.

With reference to Figure 4A, an electrical component 13 is now described, the component comprising a support 14 and at least one conducting element 18, such a support 14 being adapted to support the conducting element 18, which is electrically insulated by means of the insulating tape 10 according to the present invention. In the example shown, the support 14 is in the form of a spool including a central body or sleeve 15, and two flanges 16 and 17, such a spool having a square section. However, a spool having other shapes can also be used, for example with a circular section, an ovoid section, or any other shape apt to allow to support at least one conducting element 18, such as for example an electrical winding.

Furthermore, the conducting element 18, shown in Figure 4A in the form of an electrical winding, again indicated with 18, can be of any other type, for instance it can be a conductive layer or a conductive portion of the electrical component 13 that needs to be insulated, such a figure being provided by way of example only and not limiting in any manner the scope of the present invention.

As apparent from Figure 4A, the edge portions 12A and 12B of the insulating tape 10 according to the present invention are in particular able to adhere to the flanges 16 and 17 of spool 14, lying thereon substantially orthogonally to the plane a of the flat central portion 1 1 of the insulating tape 10, thus allowing a suitable insulation of the electrical winding 18, this bending of the insulating tape 10 being allowed by the presence of the ripple OND of the edge portions 12A and 12B.

Suitably, as shown in Figure 4B, which illustrates a variant of the electrical component 13 of Figure 4A, the ripple OND of the edge portions 12A and 12B allows insulating the electrical winding 18 even when a flange, the flange 16 in the example of figure 4B, of the spool 14 has a wall interruption 19. Indeed, it is apparent that the corresponding edge portion, the portion 12A in the example, of the insulating tape 10 can easily adhere to that flange 16, and thus can maintain appropriate clearance and creepage distances, even at the wall interruption 19.

It is also worth noting that, although only one electrical winding 18 is shown in Figures 4A and 4B, the electrical component 13 may comprise any number of electrical windings, which are insulated by means of the insulating tape 10, these figures being provided only by way of non- limiting example of the present invention in order to understand the operation of the insulating tape 10 within an electrical component.

The insulating tape 10 according to the present invention has a thickness and a width, measured in a direction orthogonal to the longitudinal (unwinding) direction of the tape, such as to enable the appropriate insulation of the electrical winding 18. In particular, the width of the insulating tape 10 is such as to allow the edge portions 12 A and 12B, provided with respective ripples OND, to adhere to the flanges 16 and 17 of the spool 14, lying thereon substantially orthogonally to the plane a of the flat central portion 1 1 of the insulating tape 10.

Referring now to Figure 5, a section of the electrical component 13 of Figure 4A is schematically shown, where the electrical winding 18, which is arranged directly on the body 15 of the spool 14, is enveloped by a further electrical winding 20. The electrical insulation between the electrical windings 18 and 20 is achieved by means of the insulating tape 10 according to the present invention, which tape adheres as described above to the flanges 16 and 17 of spool 14 at the edge portions 12A and 12B thereof. The electrical component 13 may be, for example, a transformer, a coupled inductor or any other electrical component comprising at least one conducting element insulated by means of the insulating tape 10 according to the present invention.

As shown in Figure 5, advantageously according to the present invention, the insulating tape 10 allows to increase the clearance and creepage distances between the electrical windings 18 and 20, without the need to increase the thickness of such an insulating tape 10, resulting in undeniable advantages in terms of manufacturing costs and performance of the electrical component 13. In fact, the presence of the ripple OND of the edge portions 12A and 12B allows those edge portions to lie on the flanges 16 and 17 of the spool 14, thus allowing a better insulation compared to flat tapes.

Moreover, the edge portions 12A and 12B, provided with the ripple OND, of the insulating tape 10 do not have physical interruptions, which instead characterizes the known fringed insulating tapes. Thereby, a suitable clearance and creepage distance can be obtained by applying a single layer of the insulating tape 10 according to the present invention, without the need of superimposing several layers thereof, resulting in reduced dimensions of the insulating portion in the electrical components.

Therefore, the insulating tape 10 according to the present invention allows increasing the clearance and creepage distance between conducting elements of an electrical component in a much simpler and more cost- effective manner than that suggested by the known solutions, also occupying smaller spaces within the electrical component.

Conveniently, the insulating tape 10 is made of common and inexpensive materials, available even in very thin layers. The insulating tape 10 is preferably made of an adhesive dielectric material, for example selected from polyethylene (known for example under the trade name Mylar), polyimide (known for example under the trade name Kapton) or any other dielectric material having appropriate physical characteristics such as to allow a plastic deformation of the edge portions 12A and 12B of the insulating tape 10 and such as to obtain an adequate dielectric strength for an electrical component whose conducting elements are insulated by means of such an insulating tape 10.

Moreover, in some applications the insulating tape 10 can be suitably manufactured starting from a multilayer structure, or a structure comprising superimposed layers of different dielectric materials, for example glued together. By way of non-limiting example, such a multilayer structure can be selected from a superposition of latheroid and polyethylene layers or a superposition of polyethylene and adhesive paper layers.

Referring again to Figure 3, the ripple OND of at least one edge portion 12A or 12B is continuously and uniformly distributed along such at least one edge portion 12A or 12B. Furthermore, as previously noted, in the embodiment shown in Figure 3, both the edge portions 12A and 12B have a ripple OND.

Alternatively, in an alternative embodiment shown in Figure 6, only one edge portion, the edge portion 12 A in the example, of an insulating tape 10' has a ripple OND, thus being adapted to be applied to a single flange of a spool 14 that accommodates an electrical winding 18.

In a further alternative embodiment shown in Figure 7, the ripple OND of at least one edge portion 12A or 12B of an insulating tape 10" is discontinuously distributed along such at least one edge portion 12A or 12B, i.e. it is made only on non-contiguous or intermittent segments of such at least one edge portion 12A or 12B. In this embodiment, the edge portion segments having the ripple OND are thus preceded and followed by edge portion segments without the ripple OND. This alternative embodiment is advantageous when a spool 14 having a square or rectangular section is used, the ripple OND being made only in the segments where the at least one edge portion 12A or 12B is located at the edges of such a spool 14. Such an embodiment is also particularly advantageous when specific requirements require the use of insulating tapes having high thickness.

With reference to Figure 8A, a method, referred to as a preferred method, for manufacturing an insulating tape 10 for electrical components is described, which insulating tape comprises a flat central portion 1 1 , lying in a plane a, and at least one edge portion 12A or 12B contiguous to the flat central portion 1 1 along a longitudinal unwinding direction of the insulating tape 10.

Advantageously according to the present invention, the method comprises the steps of: - providing the insulating tape 10 to a forming device 20 comprising at least one pair of toothed wheels 21A or 2 IB, such at least one pair of toothed wheels 21A or 2 IB being provided with a plurality of mutually engaged teeth 22, the insulating tape 10 being provided so that such at least one edge portion 12A or 12B is trapped at the plurality of mutually engaged teeth 22;

- rotating the at least one pair of toothed wheels 21A or 2 IB, so that the at least one edge portion 12A or 12B is pulled through the plurality of mutually engaged teeth 22; and - forming by stretching the at least one edge portion 12A or 12B by means of the plurality of teeth 22 of the at least one pair of toothed wheels 21A or 2 IB, by impressing a ripple OND to such at least one edge portion 12A or 12B with respect to the plane a of the flat central portion 1 1. As shown in Figure 8A, the forming device 20 comprises a first pair of toothed wheels 21A and a second pair of toothed wheels 2 IB, such a first pair of toothed wheels 21A and such a second pair of toothed wheels 2 IB being provided with respective pluralities of mutually engaged teeth, all indicated by the numerical reference 22, which teeth 22 impress the ripple OND to respective edge portions 12A and 12B of the insulating tape 10, the edge portions 12A and 12B being arranged on opposite sides of the flat central portion 1 1 and being contiguous thereto along a longitudinal unwinding direction of the insulating tape 10.

The step of forming by stretching at least one edge portion 12A or 12B by means of the plurality of teeth 22 provides the formation of a ripple OND having a pattern, pitch and width corresponding to a profile, pitch and height of the teeth of the plurality of teeth 22, respectively.

Moreover, a toothed wheel of the pair of toothed wheels 21A and of the pair of toothed wheels 2 IB has chamfered teeth, such a chamfer having a variable shape as a function of the transverse progressivity of the ripple OND to be impressed to the insulating tape 10.

Both the toothed wheels of the pair of toothed wheels 21A and of the pair of toothed wheels 2 IB can be rotated by respective motor means (not shown), or only one toothed wheel can be rotated, the rotation of such a toothed wheel causing the rotation of the other toothed wheel due to the mutual engagement of the plurality of teeth 22.

In an alternative embodiment shown in Figure 8B, at least one pair of toothed wheels 21A or 2 IB of the forming device 20 comprises a plurality of teeth 22 distributed in a discontinuous manner, i.e. having toothed segments preceded and followed by untoothed segments. Thereby, during the step of forming-by- stretching, a ripple OND is impressed on at least one edge portion 12A or 12B of an insulating tape 10", the ripple OND being discontinuously distributed along such at least one edge portion 12A or 12B. Alternatively, the step of rotating at least one pair of toothed wheels 21A or 2 IB of the forming device 20 can comprise a cadenced distancing of a toothed wheel of the at least one pair of toothed wheels 21A or 2 IB from the other toothed wheel, as indicated by arrow I in Figure 8A, so that during the step of forming-by- stretching, a ripple OND is anyway impressed on at least one edge portion 12A or 12B of the insulating tape 10", the ripple OND being discontinuously distributed along the at least one edge portion 12A or 12B.

The cadenced distancing I of the toothed wheel can be varied according to specific needs in order to generate different lengths of the segments of the at least one edge portion 12A or 12B with ripple OND and without ripple OND, such lengths being variable as a function of the shape of spool 14, for example, and being possibly adaptable for insulating a plurality of sequentially superimposed electrical windings. In particular, the time when the teeth of the toothed wheels are mutually engaged can be changed according to specific needs, thus determining the length of the segment with ripple OND, as well as the time when the toothed wheels are moved away from each other and the respective teeth are not mutually engaged can be changed, thus determining the length of the segment without ripple OND.

In this alternative embodiment, both the toothed wheels of the pairs of toothed wheels 21A and 2 IB are rotated by means of respective motor means (not shown), the relative movement thereof being synchronized.

Before the step of forming by stretching at least one edge portion 12A or 12B, the edges of the insulating tape 10, 10', 10" can conveniently be heated, e.g. by means of a hot air jet or another suitable method.

It is worth noting that, although the above method is preferred, other methods for manufacturing the insulating tape 10, 10', 10" are also possible. It is also worth noting that the ripple OND obtained by stretching, and therefore the resulting thickness reduction of the edge portions 12A and 12B, does not degrade the performance of the insulating tape 10, 10, 10". Indeed, the insulating power lost due to the thickness reduction of the edge portions 12A and 12B of the insulating tape 10 is restored, perhaps increased, due to the greater clearance distance between the conducting elements, which increased distance is obtained due to the ripple OND of such edge portions 12A and 12B.

In conclusion, the present invention provides an insulating tape for electric components, wherein at least one edge portion of such an insulating tape has a ripple with respect to a plane of a flat central portion thereof.

Compared to the fringed tapes of the prior art, such an insulating tape has no physical interruptions of the edge portions, which interruptions are risky in terms of undesirable current flows, but the edge portions thereof suitably have a ripple, which can be continuously or discontinuously distributed. Therefore, by using the insulating tape according to the present invention, there is no need to superimpose several layers of insulating material to achieve the required isolation, with consequent economic advantages.

Furthermore, advantageously according to the present invention, the possibility of obtaining an increase in clearance and creepage distances by applying only one layer of the insulating tape allows to reduce the dimensions of the insulating material and thus to improve the performance of an electrical component whose conducting elements are insulated by means of this tape. In fact, the performance of an electrical component, such as a transformer, are known to depend on the thickness of the insulating material used to insulate its conducting elements.

In particular, the sizes and structure being equal, the smaller dimension of insulating material allows obtaining a greater electric power per unit volume, with minor losses for an electrical component comprising such an insulating tape due to the lower ohmic DC and AC resistances that can be obtained, resulting in greater energy efficiency.

Moreover, the smaller dimensions of insulating material in an electrical component due to the use of thinner tapes and to the reduction of the spaces possibly occupied by side insulations, such as the steps of insulating material 8 in Figure 2A or the layers of adhesive insulating tape 8' in Figure 2B, allows to obtain a reduction of the lost inductance compared to the electrical components according to the prior art, which results in considerable advantages. For example, in the case of transformers for flyback converters, such a reduction of the lost inductance leads to a reduction of the dissipated heat from snubbers placed to protect the active components, resulting in a greater energy efficiency, and to less stress on the active components themselves due to the reduction of the reflected voltage on the primary electrical winding during switching operations, resulting in higher reliability or cost reduction, since active components with lower maximum voltage can be used. It is also worth noting that most of the small transformers for electronics where a reinforced insulation is required are obtained by using a triple insulated wire for at least one of the electrical windings, typically the secondary electrical winding, and in such cases the regulations for the reinforced insulation do not impose a minimum thickness of the insulation interposed between the primary electrical winding and the secondary electrical winding.

In general terms, in the field of transformers, the reduction in the lost inductance implies further considerable advantages, especially related to a minor variation of the secondary voltage as the load varies. Moreover, the insulating tape according to the present invention allows to obtain a greater certainty on the clearance and creepage distances obtainable compared to the fringed tapes, in addition to the use of common and particularly thin insulating materials, thus allowing to obtain a high insulation with small dimensions for the insulating material. Finally, advantageously, the insulating tape according to the present invention allows to obtain an increase of the creepage and clearance distances in a much simpler manner compared to the known solutions, without employing multi-layer configurations and without needing to build insulation barriers on the support of the conducting elements, with undeniable advantages especially when manufacturing small components which require a high isolation. In particular, an increase in the dielectric strength can be obtained for an electrical component whose conducting elements are insulated by means of such an insulating tape, up to values substantially from 2 to 4 kV if both electrical windings are made of enameled wire, or from 4 to 8 kV if one of the electrical windings is made of a triple insulated wire, even with very small spaces occupied by the insulating tape itself.

Obviously, a person skilled in the art, in order to meet particular needs and specifications, can carry out several changes and modifications to the insulating tape described above, all included in the protection scope of the invention as defined by the following claims.

Claims

1. An insulating tape (10, 10', 10") apt to be wound around conducting elements of electrical components for their insulation, said insulating tape (10, 10', 10") comprising a flat central portion (1 1), lying in a plane (a), and at least one edge portion (12A, 12B) contiguous to said flat central portion (1 1) along a longitudinal unwinding direction of said insulating tape (10, 10', 10"), characterized in that said at least one edge portion (12A, 12B) has a ripple (OND) with respect to said plane (a) of said flat central portion (1 1).

2. The insulating tape (10, 10', 10") according to claim 1 , characterized in that said at least one edge portion (12A, 12B) is plastically deformed at said ripple (OND).

3. The insulating tape (10, 10', 10") according to claim 1 or 2, characterized in that it comprises respective edge portions (12A, 12B) arranged on opposite sides of said flat central portion (1 1) and contiguous thereto along a longitudinal unwinding direction of said insulating tape (10, 10', 10"), both said edge portions (12A, 12B) having a ripple (OND).

4. The insulating tape (10, 10', 10") according to any one of the preceding claims, characterized in that it is made of an adhesive dielectric material.

5. The insulating tape (10, 10', 10") according to any one of the claims from 1 to 3, characterized in that it comprises a multilayer structure including a superposition of different dielectric material layers.

6. The insulating tape (10, 10') according to any one of the preceding claims, characterized in that said ripple (OND) of said at least one edge portion (12A, 12B) is distributed in a continuous manner along said at least one edge portion (12A , 12B).

7. The insulating tape (10") according to any one of the claims from 1 to 5, characterized in that said ripple (OND) of said at least one edge portion (12A, 12B) is distributed in a discontinuous manner along said at least one edge portion (12A, 12B).

8. An electrical component (13) comprising at least one conducting element (18), characterized in that said at least one conducting element (18) is insulated by means of an insulating tape (10, 10', 10") according to any one of the preceding claims.

9. The electrical component (13) according to claim 8, characterized in that said at least one conducting element (18) is an electrical winding.

10. The electrical component (13) according to claim 9, characterized in that it is selected from a transformer and a coupled inductor.

1 1. A method for manufacturing an insulating tape (10, 10', 10") apt to be wound around conducting elements of electrical components, said insulating tape (10, 10', 10") comprising a flat central portion (1 1), lying in a plane (a), and at least one edge portion (12A, 12B) contiguous to said flat central portion (1 1) along a longitudinal unwinding direction of said insulating tape (10, 10', 10"), said method comprising the steps of:

- providing said insulating tape (10, 10', 10") to a forming device (20) comprising at least one pair of toothed wheels (21 A, 2 IB), said at least one pair of toothed wheels (21 A, 2 IB) being provided with a plurality of teeth (22) that are mutually engaged, said insulating tape (10, 10', 10") being provided so that said at least one edge portion (12A, 12B) is trapped at said plurality of mutually engaged teeth (22); - rotating said at least one pair of toothed wheels (21A, 2 IB), so that said at least one edge portion (12A, 12B) is pulled through said plurality of mutually engaged teeth (22); and

- forming by stretching said at least one edge portion (12A, 12B) by means of said plurality of teeth (22) of said at least one pair of toothed wheels (21 A, 2 IB), by impressing a ripple (OND) to said at least one edge portion (12A, 12B) with respect to said plane (a) of said flat central portion (1 1).

12. The method for manufacturing an insulating tape (10, 10', 10") according to claim 1 1, wherein said forming device (20) comprises a first pair of toothed wheels (21 A) and a second pair of toothed wheels (2 IB), said first pair of toothed wheels (21 A) and said second pair of toothed wheels (2 IB) being provided with respective plurality of teeth (22) that are mutually engaged, said plurality of teeth (22) impressing said ripple (OND) to respective edge portions (12A, 12B) of said insulating tape ( 10, 10', 10"), said respective edge portions (12A, 12B) being arranged on opposite sides of said flat central portion (1 1) and contiguous thereto along a longitudinal unwinding direction of said insulating tape (10, 10', 10").

13. The method for manufacturing an insulating tape (10, 10', 10") according to claim 1 1 or 12, wherein said at least one pair of toothed wheels (21A, 2 IB) of said forming device (20) comprises a plurality of teeth (22) distributed in a discontinuous manner, so that said step of forming by stretching impresses a ripple (OND) on said at least one edge portion (12A, 12B) of said insulating tape (10"), said ripple (OND) being distributed in a discontinuous manner along said at least one edge portion (12A , 12B).

14. The method for manufacturing an insulating tape (10") according to claim 1 1 or 12, wherein the step of rotating comprises a cadenced distancing of a toothed wheel of said at least one pair of toothed wheels (21 A, 2 IB) with respect to the other toothed wheel, so that said step of forming by stretching impresses a ripple (OND) on said at least one edge portion (12A, 12B) of said insulating tape (10"), said ripple being distributed in a discontinuous manner along said at least one edge portion (12A, 12B), said cadenced distancing being changed according to specific needs.