WO2023012662A1

WO2023012662A1 - Method for the electromagentic insulation of components of an electric motor

Info

Publication number: WO2023012662A1
Application number: PCT/IB2022/057162
Authority: WO
Inventors: Raffaele DONAZZON; Nicola Bianchi; Enrico Bernardo
Original assignee: Università Degli Studi Di Padova
Priority date: 2021-08-03
Filing date: 2022-08-02
Publication date: 2023-02-09
Also published as: IT202100020936A1

Abstract

The present disclosure relates to a method for the electromagnetic insulation of a first conductive element (1) and a second conductive element (2) of a stator and/or rotor of an electric motor. The method comprises the steps of: - coating the first conductive element (1) and the second conductive element (2) with at least on insulating compound (A, B) configured, during use, to insulate electromagnetically the first conductive element (1) and the second conductive element (2). The at least one insulating compound (A, B) comprises at least one preceramic polymer. - drying said first conductive element (1) and said second conductive element (2) coated with said at least one insulating compound (A, B). - coating said first conductive element (1) with a sealing compound (C) comprising a preceramic polymer and configured to favour adhesion of this second conductive element (2) to said first conductive element (1)' - assembling the first conductive element (1) and second conductive element (2) to form the stator of said electric motor; - heat treating the assembled first conductive element (1) and the said second conductive element (2). Said heat treatment comprises heating the first conductive element (1) and the second conductive element (2) up to a temperature of at least 350°C and subsequent cooling thereof. The present invention also relates to an electric motor comprising a first conductive element (1) and a second conductive element (2) electromagnetically insulated by means of the method described.

Description

METHOD FOR THE ELECTROMAGENTIC INSULATION OF COMPONENTS OF AN ELECTRIC MOTOR

DESCRIPTION

The present disclosure relates in general to the technical sector of electric motors and in particular refers to a method for the electromagnetic insulation of electrical conductive components present in an electric motor. More particularly, the present disclosure relates to a method for providing a high-temperature insulating coating of ceramic material obtained by means of preceramic polymers.

In the sector of electric motors it is of fundamental importance to use insulating coatings in order to protect the electromagnetic conductive components inside the motor and ensure optimum electrical insulation with respect to the exterior and provide the components with a chemical resistance, for example against corrosion, and a thermal resistance, in particular for temperatures above 600°C.

According to the prior art, two different solutions are mainly used for the insulation of the conductive components of an electric motor. A first solution involves the use of insulants made of polymer materials, which ensure a constructional simplicity owing to the numerous production processes which may be used for the manufacture thereof at relatively low temperatures. This solution, however, has major drawbacks, for example the polymer materials have a low resistance to ultraviolet radiation and to high temperatures, which may cause the deterioration thereof and the loss of the insulating properties, making it often necessary to use a cooling system inside the motor.

In order to overcome this problem it is known to use ceramic or vitreous enamels as insulating coating for the conductive components to be protected. This solution ensures an optimum resistance to high temperatures. However, the use of these materials is particularly disadvantageous in that it requires a complex construction and laying process which must be performed at high temperatures and may result in a coating which is fragile at room temperature.

The technical problem underlying the present disclosure is therefore that of providing an insulating coating for the electromagnetic conductive components of an electric motor which is able to satisfy the requirements mentioned above with regard to the prior art and overcome the aforementioned problems and/or which is able to achieve further advantages. This is obtained by means of a method for the electromagnetic insulation of conductive elements of an electric motor and an electric motor comprising the conductive components obtained with the aforementioned method according to the respective independent claims. Secondary characteristic features of the present disclosure are defined in the corresponding dependent claims.

The present disclosure is based on the recognition by the inventor that it is possible to solve the problems of the solutions according to the prior art by using a coating which comprises a preceramic polymer which is subjected to ceramization following application onto the electromagnetic conductive elements.

A coating of this type, in fact, offers the advantage of simple construction and laying, typical of polymer coatings, for example using a paste or a compound having a viscosity such that it may be easily applied onto the element to be coated. Moreover, following application of the coating and a heat treatment which allows ceramization by means of pyrolysis of the preceramic compound, it is possible to obtain a ceramic compound, known as a “polymer derived ceramic” (PDC), which has chemical and thermal resistance characteristics typical of ceramic materials.

In this way it is possible to obtain a final coating which has optimum chemical and thermal resistance and which is very simple to apply onto the conductive elements of the electric motor, thereby overcoming the drawbacks associated with the current solutions of the prior art.

In detail, the method according to the present disclosure is aimed at performing the electromagnetic insulation of a first conductive element and a second conductive element of an electric motor. In detail, the first conductive element and the second conductive element may be conductive elements of a stator and/or of a rotor of an electric motor, preferably of a stator of an electric motor.

This method comprises a step of coating the first and second conductive elements with at least one insulating compound which is configured, during use, to insulate electromagnetically said first and second conductive elements. The at least one insulating compound comprises at least one preceramic polymer. The method then involves a step of drying, preferably air drying, the two conductive elements coated with the at least one insulating compound. Furthermore, the method comprises a further step of coating the first conductive element with a sealing compound, which also comprises a preceramic polymer, and which is configured to favour adhesion of the second conductive element to the first conductive element. Thereafter the method involves assembling the first conductive element and the second conductive element so as to form the electric motor, preferably the stator of said electric motor. The assembled first conductive element and the second conductive element are then thermally treated with heating up to a temperature of at least 350°C and subsequent cooling. Advantageously, above 350°C, the silicones complete a first transformation, resulting in the formation of a crosslinked molecular structure.

According to a preferred aspect of the present disclosure, the at least one insulating compound comprises a silicone element and/or a vitreous element and/or alumina.

Preferably, the at least one insulating compound comprises all three elements. In detail, alumina is an optimum electrical insulant, but when used on its own requires sintering at high temperature, above 1600°C. Silicone is optimum for obtaining an insulating compound which can be realized at lower temperatures, since it converts into vitreous silica above 500°C. The silicone, together with alumina, advantageously creates a silica-alumina compound. The addition of a vitreous element furthermore allows the dilution of the silicone and the formation of a high-temperature liquid phase able to seal advantageously any cracks in the silica-alumina compound.

In other words, therefore, the alumina provides the insulating compound with electromagnetic insulation characteristics, while the silicone element and the vitreous element help cement the insulating compound to the conductive elements both at low temperatures and at high temperatures.

In combination with or instead of alumina, it is possible to use other materials, provided that they are good electromagnetic insulants and are not chemically reactive in a temperature range of between 0°C and 600°C.

According to a further aspect of the present disclosure, the at least one insulating compound comprises a first insulating compound and a second insulating compound. In this respect, the coating step involves coating the first conductive element with the first insulating compound and coating the second conductive element with the second insulating compound.

Advantageously, the first compound allows thicker coating of the first conductive element, making more difficult the expulsion of gas from the subsequent heat treatment step. Moreover, advantageously, the first insulating compound may have a greater vitreous element content, thereby favouring the sealing of any cracks which may form during the heat treatment step.

In detail, according to a preferred aspect, the first insulating compound has the following composition (wt%): 12% ± 3% of a first silicone compound, preferably silicone H44®, 5% ± 3% of isopropanol, 7.5% ± 3% of a second silicone compound, preferably silicone H62C®, 57% ± 3% of alumina, 8.5% ± 3% of glass, 2% ± 3% of triethylamine, 8.5% ± 3% of distilled water. According to this aspect, moreover, the second insulating compound has the following composition (wt%): 22% ± 3% of said first silicone compound, preferably silicone H44®, 9% ± 3% of isopropanol, 14% ± 3% of said second silicone compound, preferably silicone H62C®, 15% ± 3% of alumina, 36% ± 3% of glass, 3.6% ± 0.3% of triethylamine. Preferably, the alumina and/or glass is/are in powder form.

Even more specifically, the first insulating compound has the following composition (wt%): 11.92% ± 3% of a first silicone compound, preferably silicone H44®, 4.74% ± 3% of isopropanol, 7.45% ± 3% of a second silicone compound, preferably silicone H62C®, 56.83% ± 3% of alumina, 8.47% ± 3% of glass, 2.12% ± 3% triethylamine, 8.47% ± 3% distilled water. According to this aspect, moreover, the second insulating compound has the following composition (wt%): 22.41% ± 3% of a first silicone compound, preferably silicone H44®, 8.97% ± 3% of isopropanol, 14.00% ± 3% of a second silicone compound, preferably silicone H62C®, 14.57% ± 3% of alumina, 36.41% ± 3% of glass, 3.64% ± 0,3% of triethylamine. Preferably, the alumina and/or glass is/are in powder form.

According to a further aspect, the sealing compound has instead the following composition (wt%): 25.00% ± 3% of a second silicone compound, preferably silicone H62C®, 75.00% ± 3% of glass. Preferably the glass is in powder form.

According to a further aspect of the present disclosure, during the step of heat treatment of the assembled first and second conductive elements, heating of the latter involves an increase in temperature of the said conductive element which is between 5°C per minute and 7.5°C per minute, and preferably equal to 5°C per minute. Advantageously, an increase in temperature of 5°C favours optimum expulsion of gas during the heat treatment step.

According to a further preferred aspect, the heat treatment step involves heating of the first conductive element and the second conductive element to a temperature of between 500°C and 600°C and keeping these first and second conductive elements at this temperature for at least 180 minutes. Advantageously, above 350°C, the silicones complete a first transformation resulting in the formation of a crosslinked molecular structure. A further increase in temperature in the range of between 500°C and 600°C allows the ceramic transformation of the silicone to occur.

Advantageously, the heat treatment step is configured to ceramize the silicone present in the at least one insulating compound and in the sealing compound. Moreover, this temperature range does not exceed the melting temperature of the glass used in the insulating compound and in the sealing compound.

According to a further preferred aspect of the present disclosure, the first conductive element and the second conductive element are conductive elements of a stator of an electric motor. Preferably, the first conductive element is a ferromagnetic core of a stator of an electric motor, while the second conductive element is a copper wire or, preferably, a copper braid of a stator of an electric motor. Advantageously, the use of a copper braid favours the adhesion of the at least one insulating compound, in detail of the second insulating compound.

The present disclosure relates furthermore to an electric motor comprising a first conductive element and a second conductive element electromagnetically insulated using the method described and claimed.

Further characteristic features and modes of use forming the subject of the present disclosure will become clear from the following detailed description of embodiments thereof, provided by way of a non-limiting example.

It is in any case evident that each embodiment of the subject of the present disclosure may have one or more of the advantages listed above; in any case it is not required that each embodiment should have simultaneously all the advantages listed.

Reference will be made to the figures of the attached drawings in which:

- Figure 1 shows a perspective view of a first conductive element of an electric motor according to one aspect of the present disclosure;

- Figure 2 shows a perspective view of a first conductive element of an electric motor coated with an insulating compound according to one aspect of the present disclosure;

- Figure 3 shows a perspective view of a second conductive element coated with at least one insulating compound and assembled on a first conductive element coated with at least one insulating compound according to one aspect of the present disclosure;

- Figure 4 shows a perspective view of two conductive elements of an electric motor assembled according to the present invention.

In the detailed description of the invention and its preferred embodiments, reference will be made to the class of preceramic polymers, this term being understood as meaning the different polymer compounds - which are generally silicon-based - configured so that they may be coated with ceramic materials by means of a heat treatment.

With reference to the attached figures, a method for the electromagnetic insulation of a first conductive element 1 and a second conductive element 2, forming part of an electric motor, comprises the steps described below. According to a first preferred embodiment, the first conductive element 1 and second conductive element 2 are electrically and/or magnetically conductive elements of a stator and/or rotor of an electric motor. Preferably, the first conductive element 1 and second conductive element 2 are electrically and/or magnetically conductive elements of a stator of an electric motor. Even more preferably, the first conductive element 1 is a ferromagnetic core of a stator of an electric motor, namely is the magnetic part of the stator having the function of channelling the magnetic flow. The second conductive element 2 is a copper wire, or more preferably a copper braid, of a stator of an electric motor, namely the portion of the stator which has the function of conducting electric current. Even more preferably, the second conductive element 2 comprises desoldering copper braids. Advantageously, these desoldering copper braids are commercially available products in which the copper does not have any insulating coating. It is however possible to use copper braids with technical characteristics similar to those of desoldering copper braids.

Initially, the method according to the present invention involves a step of coating the first conductive element 1 and the second conductive element 2 with at least one insulating compound A, B. Said at least one insulating compound A, B is configured, during use, to insulate electromagnetically the first conductive element 1 and the second conductive element 2.

The at least one insulating compound A, B comprises at least one preceramic polymer.

The expression “preceramic polymer” is understood as meaning, in the context of the present disclosure, a polymer compound which may, for example by means of pyrolysis, be converted into a ceramic compound having advantageously both a high thermal stability and high chemical stability.

In greater detail, the at least one insulating compound A,B comprises a vitreous material and a material based on a non-vitreous oxide, i.e. an oxide able to form a crystal lattice. Preferably, the vitreous material and the material based on a non-vitreous oxide are added to the at least one insulating compound A, B in the form of powders.

For example, the at least one insulating compound may comprise a silicone-based preceramic polymer, a vitreous material, such as sodium phosphate or boric anhydride and aluminium oxide or alumina Preferably, the material based on a non-vitreous oxide is a material which is electrically insulating and thermally inert when close to the maximum temperature of a heat treatment step, described below in detail.

Preferably, the vitreous material of the at least one insulating compound A, B has a melting temperature higher than the temperature of the step for heat treatment of the first conductive element 1 and the second conductive element 2. Moreover, the vitreous material preferably has a glass transition temperature such that, during heat treatment, a vitreous transition of the vitreous material towards a less viscous phase is possible.

Preferably, the at least one insulating compound A, B furthermore comprises alumina. In combination with or as alternative to alumina, the at least one insulating compound A, B may comprise materials which are not vitreous, are good electrical insulants and are not reactive within the temperature range of the heat treatment step described below.

The method according to the invention then involves a step of drying the first conductive element and the second conductive element 1, 2 which are coated with the at least one insulating compound A, B.

According to a preferred aspect of the present invention, the at least one insulating compound A, B comprises a first insulating compound A and a second insulating compound B.

According to this aspect, the step for coating the first and second conductive elements 1 , 2 involves coating the first conductive element with the first insulating compound A and coating the second conductive element 2 with the second insulating compound B.

In detail, the first insulating compound A comprises at least a silicone element and a vitreous element. Preferably, the first insulating compound A furthermore comprises alumina. More specifically, the first insulating compound A has the following composition, expressed as a percentage of the overall weight of the said compound A.

12% ± 3%, preferably 11.92% ± 3% of a first silicone compound, preferably silicone H44®. Advantageously the silicone H44® can be mixed with the second silicone compound, preferably silicone H62C® and ensures a good ceramic yield, namely a relatively high ratio between the polymer mass which is converted into silica during the heat treatment and the initial polymer mass;

5% ± 3%, preferably 4.74% ± 3%, of isopropanol;

7.5% ± 3%, preferably, 7.45% ± 3%, of a second silicone compound, preferably silicone H62C®. Advantageously, silicone H62C® is a liquid silicone which is optimum for mixing with the other low-temperature components.

57% ± 3%, preferably 56.83% ± 3%, of alumina, preferably alumina in powder form;

8.5% ± 3%, preferably, 8.47% ± 3%, of glass, preferably glass in powder form;

2% ± 0.3%, preferably 2.12% ± 0.3%, of triethylamine;

8.5% ± 3%, preferably 8.47% ± 3%, of water, preferably distilled water.

Preferably, for production of the first insulating compound A the steps described below are carried out. The first silicone compound, preferably H44®, which is preferably in powder form, is dissolved in isopropanol until a gel is obtained. Preferably, the first silicone compound comprises a phenyl silicone resin, preferably in powder form. The second silicone compound, preferably silicone H62C®, preferably in liquid form, is then added to said gel and the product is mixed until a uniform compound is obtained. Preferably, the second silicone compound comprises a formulation, preferably phenyl silicone resin liquid, which is preferably mono-component, preferably without solvents, and thermosetting. Then alumina and glass, preferably both in powder form, are added and then mixing is performed, preferably using a machine, preferably at 2000 rpm, preferably for at least 2 minutes. Then the triethylamine is added, this advantageously acting as a cross-linker, and mixing is performed until the compound has a uniform viscosity. Then water, preferably distilled water, is added and mixing of the compound is carried out until the silicone forms a dense paste. Finally, preferably, further mixing is performed, preferably using a machine, preferably at 2000 rpm, preferably for at least 2 minutes. The purpose of this final mixing step is to remove any excess air present in the compound.

As regards the vitreous material, it is preferable to use sodium phosphate or boric anhydride. Different glass materials, however, may be used. However, it should be taken into account that, in general, the greater the percentage of sodium in the vitreous material, the less will be the electrical insulation of the resultant insulating compound. Moreover, it is necessary that the glass transition temperature of the selected vitreous material should correspond to the temperature of the heat treatment step described below. Finally, the melting temperature of the selected vitreous material must not be less than the treatment and operating temperatures of the electric motor composed of the first conductive element 1 and the second conductive element 2.

According to a preferred aspect, the step of coating the first conductive element 1 with the first insulating compound A involves the latter onto the said first conductive element 1. In detail, in the case where the first conductive element 1 is a ferromagnetic core of a stator of an electric motor, the first insulating compound A is spread in the zones of the lamination pack around which the copper turns will be then wound. In detail, the first insulating compound A is spread so as to obtain, in the first conductive element 1, a thin and uniform layer, namely one which does not have holes or projections. Preferably, the first conductive element 1 is coated with the first insulating compound A within an hour of addition of the cross-linker, preferably triethylamine.

Preferably, the step of drying the first conductive element 1, which is coated with the first insulating compound A, involves drying in air and preferably at room temperature. Preferably, said drying step has a duration of at least 24 hours.

The second insulating compound B comprises at least a silicone element and a vitreous element. Preferably, the second insulating compound B furthermore comprises alumina. More specifically, the second insulating compound B has the following composition, expressed as a percentage of the overall weight of the said compound A:

22% ± 3%, preferably 22.41% ± 3%, of a silicone compound, preferably said first silicone compound, preferably silicone H44®. Advantageously the silicone H44® can be mixed with the second silicone compound, preferably silicone H62C® and ensures a good ceramic yield, namely a relatively high ratio between the polymer mass which is converted into silica during the heat treatment and the initial polymer mass;

9% ± 3%, preferably 8.97% ± 3%, of isopropanol;

14% ± 3% of a silicone compound, preferably said second silicone compound, preferably silicone H62C®; Advantageously, the second silicone compound, preferably silicone H62C® is a liquid silicone which is optimum for mixing with the other low-temperature components;

15% ± 3%, preferably 14.57% ± 3%, of alumina, preferably alumina in powder form;

36% ± 3%, preferably 36.41% ± 3%, of glass, preferably glass in powder form; 3.6% ± 0.3%, preferably 3.64% ± 0.3%, of triethylamine.

Preferably, for production of the second insulating compound B the steps described below are carried out: The first silicone compound, preferably H44®, which is preferably in powder form, is dissolved in isopropanol until a gel is obtained. The second silicone compound, preferably silicone H62C®, preferably in liquid form, is then added to said gel and the product is mixed until a uniform compound is obtained. Then alumina and glass, preferably both in powder form, are added and then mixing is performed, preferably using a machine, preferably at 2000 rpm, preferably for 2 minutes. Then the triethylamine is added, this advantageously acting as a cross-linker, and mixing is performed until the compound has a uniform viscosity. Preferably, moreover, before coating the second conductive element 2 with the second insulating compound B, further isopropanol is added so that the compound has a sufficient viscosity.

As already mentioned with regard to the first insulating compound A, also in the case of the vitreous material of the second insulating compound B, it is preferable to use sodium phosphate or boric anhydride. Different glass materials, however, may be used. However, it should be taken into account that, in general, the greater the percentage of sodium in the vitreous material, the less will be the electrical insulation of the resultant insulating compound. Moreover, it is necessary that the glass transition temperature of the selected vitreous material should correspond to the temperature of the heat treatment step described below. Finally, the melting temperature of the selected vitreous material must not be less than the treatment and operating temperatures of the electric motor composed of the first conductive element 1 and the second conductive element 2.

Preferably, the step of coating the second conductive element 2 with the second insulating compound B involves immersing the second conductive element 2 in the second insulating compound B, prepared, for example and preferably, as described above. Them the step of drying the second conductive element 2 coated with the second insulating compound B is performed. Preferably, said drying step is performed by hanging up the second conductive element 2 and lasts preferably at least 24 hours. Preferably, the step of drying the second conductive element 2 is performed in air and at room temperature. During this drying step, where the second conductive element 2 is a copper braid, it should be ensured that this braid is not twisted or coiled onto itself and that it is not in contact with other objects so as to obtain uniform drying. Irrespective as to the structure of the second conductive element 2, it is in any case important to check that the latter, during the drying step, is free and not in contact with further objects. Furthermore, preferably, during the drying of the second conductive element 2, the method may involve checking the viscosity of the second insulating compound B. In particular, this checking step involves examining the distribution of the second insulating compound B in the second conductive element 2. In the case where the second insulating compound B does not adhere properly to the second conductive element 2, the viscosity of said second insulating compound is too low, while if any drops of the second insulating compound B harden on the conductive element 2, the viscosity of said second insulating compound B is too high. In the case where these situations arise, the method involves preferably further coating the second conductive element 2 with the second insulating compound B. In combination with or as an alternative to said further coating of the second conductive element 2 with the second insulating compound B, the method according to the present invention may involve modifying the viscosity of the second insulating compound B, reducing it, for example by adding a suitable solvent, preferably isopropanol.

Once the first conductive element 1 and the second conductive element 2 have been coated with the at least one insulating compound A, B (preferably the first conductive element 1 with the first insulating compound A and the second conductive element 2 with the second insulating compound B) and once said first and second conductive elements 1 , 2 have been dried, the method according to the present invention envisages coating the first conductive element 1 with a sealing compound C. This sealing compound C comprises at least one preceramic polymer. In greater detail, the sealing compound C comprises at least a silicone element and a vitreous element. The sealing compound C is configured to favour adhesion of the second conductive element 2 to the first conductive element 1.

Preferably, the sealing compound C has the following composition, expressed as a percentage of the total weight of the said sealing compound C:

25% ± 3% of a silicone compound, preferably said second silicone compound, preferably silicone H62C®.

75% ± 3% glass, preferably in powder form.

Preferably, in order to prepare the sealing compound C, the silicone and the glass are mixed until the silicone is completely absorbed. Preferably, the sealing compound C has the form of a uniform paste with a creamy appearance.

Preferably, the coating of the first conductive element 1 with the sealing compound C involves spreading the latter over the zones of the first conductive element 1 coated with the at least one insulating compound A, B, preferably with the first insulating compound A. In this way, the sealing compound C may act as cement for the second conductive element 2 and may close, or cover, any cracks in the first conductive element 1 which may form during subsequent heat treatment thereof.

The method according to the present invention furthermore involves assembly of the first conductive element 1 and the second conductive element 2 so as to form, preferably, a stator of an electric motor. Preferably, this assembly step involves winding the second conductive element 2 around the first conductive element 1 so as to form a plurality of spiral turns.

In detail, preferably, said step involves winding the copper braid of the second conductive element 2, coated with the second insulating compound B, around the ferromagnetic core of the first conductive element 1. In the case where two or more turns of the copper braid of the second conductive element 2 are superimposed around the first conductive element 1, the method according to the present invention may comprise a step of spreading a further sealing compound C between one turn and the next one.

Thereafter, the method may comprise a step of compressing the second conductive element 2 around the first conductive element 1, in particular the copper braid, so as to remove, advantageously, any excess sealing compound C and increase the winding density of the copper braid around the first conductive element 1.

The method according to the present invention furthermore involves a heat treatment of the first conductive element 1 and the conductive element 2, once assembled. This heat treatment step involves heating the first and second conductive elements 1, 2 to a temperature of at least 350°C. Then the heat treatment involves cooling the first and second conductive elements 1, 2. Advantageously, this heat treatment step is necessary in order to ceramize the silicone present in the at least one insulating compound A, B and in the sealing compound C.

In greater detail, preferably, the heat treatment step of heating the assembled first conductive element 1 and the second conductive element 2 comprises heating the first conductive element 1 and the second conductive element 2 up to a temperature of between 500°C and 600°C, preferably between 520°C and 570°C, even more preferably about 550°C. Moreover, the first conductive element 1 and the second conductive element 2 are preferably kept at the temperature of between 500°C and 600°C for at least 180 minutes. The maximum temperature reached by the first and second conductive elements 1, 2 is in any case lower than the melting temperature of the glass used in the at least one insulating compound A, B and in the sealing compound C.

Then, preferably, the first conductive element 1 and the second conductive element 2 are allowed to cool, preferably naturally by means of convection.

According to a preferred aspect, the heating of the first conductive element 1 and the second conductive element 2 involves an increase in temperature of the first conductive element 1 and the second conductive element 2 equal to 5°C/min.

The present invention also relates to an electric motor comprising a first conductive element 1 and a second conductive element 2 which are electromagnetically insulated by means of the method described above in its various embodiments.

The present invention, described in accordance with the preferred embodiments, is able to achieve the task and objects proposed in order to overcome the drawbacks of the prior art. The subject-matter of the present disclosure has been described hitherto with reference to embodiments thereof. It is to be understood that other embodiments relating to the same inventive idea may exist, all of these falling within the scope of protection of the claims which are illustrated below.

Claims

CLAIMS Method for the electromagnetic insulation of a first conductive element (1) and a second conductive element (2) of a stator and/or rotor of an electric motor, wherein said method comprises the steps of: coating said first conductive element (1) and said second conductive element (2) with at least one insulating compound (A, B) configured, in use, to electromagnetically insulate said first conductive element (1) and said second conductive element (2), wherein said at least one insulating compound (A, B) comprises at least one preceramic polymer; drying said first conductive element (1) and said second conductive element (2) coated with said at least one insulating compound (A, B); coating said first conductive element (1) with a sealing compound (C) comprising a preceramic polymer and configured to favour adhesion of said second conductive element (2) to said first conductive element (1); assembling said first conductive element (1) and second conductive element (2) so as to form said stator of said electric motor; heat treating said assembled first conductive element (1) and said second conductive element (2), wherein said heat treatment step comprises heating said first conductive element (1) and second conductive element (2) up to a temperature of between 500°C and 600°C and subsequent cooling of said first conductive element (1) and said second conductive element (2). Method according to the preceding claim, wherein said at least one insulating compound (A, B) comprises at least a silicone element and/or a vitreous element and/or alumina. Method according to claim 1 or 2, wherein said at least one insulating compound (A, B) comprises a first insulating compound (A) and a second insulating compound (B), wherein said step of coating said first conductive element (1) and said second conductive element (2|) with at least one insulating compound (A, B) involves coating said first conductive element (1) with said first insulating compound (A) and coating said second conductive element (2) with said second insulating compound (B). Method according to the preceding claim, wherein said first insulating compound (A) has the following composition (wt%): 12% ± 3% of a first silicone compound, 5% ± 3% isopropanol, 7.5% ± 3% of a second silicone compound, 57% ± 3% alumina, 8.5% ± 3% glass, 2% ± 0.3% triethylamine, 8.5% ± 3% distilled water; and wherein said second insulating compound (B) has the following composition (wt%): 22% ± 3% of said first silicone compound, 9% ± 3% isopropanol, 14% ± 3% of said second silicone compound, 15% ± 3% alumina, 36% ± 3% glass, 3.% ± 0.3% triethylamine. Method according to any one of the preceding claims, wherein said sealing compound (C) has the following composition (wt%): 25.00 ± 3% of said second silicone compound, 75.00 ± 3% glass. Method according to any one of the preceding claims, wherein, during said step of heat treating, said heating of said first conductive element (1) and second conductive element (2) involves an increase in temperature of said first conductive element (1) and second conductive element (2) of 5°C/min. Method according to any one of the preceding claims, wherein said step of heat treating said assembled first conductive element (1) and said second conductive element (2) comprises heating said first conductive element (1) and second conductive element (2) up to a temperature of between 500°C and 600°C, wherein said first conductive element (1) and said second conductive element (2) are kept at said temperature of between 500°C and 600°C for at least 180 minutes. Method according to any one of the preceding claims, wherein said first conductive element (1) is a ferromagnetic core of a stator of an electric motor and wherein said second conductive element (2) is a copper wire or, preferably, a copper braid of a stator of an electric motor. Method according to the preceding claim, wherein said first conductive element (1) is an element made of ferromagnetic material and wherein said second conductive element (2) is a wire or a braid of wires of electrically conductive material. Electric motor comprising a first conductive element (1) and a second conductive element (2) electromagnetically insulated by means of the method according to any one of the preceding clams.