WO2022219047A1

WO2022219047A1 - Electrical insulator of a wound stator

Info

Publication number: WO2022219047A1
Application number: PCT/EP2022/059884
Authority: WO
Inventors: Geoffrey WILQUIN; Sébastien Leclercq; Stéphane CHOCHOIS; Jérémie LAMORILLE
Original assignee: Valeo Equipements Electriques Moteur
Priority date: 2021-04-14
Filing date: 2022-04-13
Publication date: 2022-10-20
Also published as: FR3122048A1; FR3122048B1; CN117480710A

Abstract

The invention relates to a wound stator (8) comprising at least one body (12) and an electrical insulator, the body (12) comprising a plurality of notches (22) receiving conductive elements (24a) of an electrical winding (24), each of the notches (22) comprising two side walls, which extend generally radially, and a bottom wall, which connects the two side walls, the electrical insulator being disposed in each of the notches (22) between the conductive elements (24a) and the walls of the corresponding notch (22), and in such a way that a zone of coverage of the electrical insulator is formed against one of the side walls of the notch (22).

Description

Title: Electrical insulation of a wound stator

The field of the present invention is that of rotating electrical machines. The invention relates more particularly to stators of such rotating electrical machines.

Such a machine can in particular be a motor vehicle alternator-starter, configured to transform mechanical energy into electrical energy and vice versa. An alternator-starter consists of a reversible alternator which makes it possible, in a first operating case, to use the mechanical energy generated during vehicle travel to recharge a battery of this vehicle and, in a second operating case, to provide an energy supply mechanical, in particular to start the heat engine of the vehicle. The machine can also be an alternator, a reversible machine or even an electric motor.

In general, a rotating electrical machine comprises a rotor that is mobile in rotation and secured to a drive shaft and a fixed stator around which, or inside which, the rotor is able to rotate.

The stator is composed of at least one body provided with a plurality of teeth forming two by two notches open on a particular internal periphery of the stator body, such that the notches are able to receive conductive elements of a electric winding. The internal radial end of each tooth forms a tooth end arranged between two neighboring notches, each tooth end being able in particular to be configured to retain the conductive elements of the winding inside their corresponding notch once in position, in particular by intermediate a tooth portion, commonly called tooth root, which extends circumferentially from the tooth tip.

The circulation of a current in the electrical winding participates in generating a rotating magnetic field effect circulating in the metallic body of the stator, and the rotor, equipped with a magnetic element, such as for example a winding or permanent magnets, is suitable to rotate inside the stator by electromagnetic drive. Reversibly, a mechanical rotational movement of the rotor equipped with a magnetic element can generate the creation, via an electromagnetic interaction with the wound stator, of an electric current in the conductive elements of the winding. It is known to arrange an electrical insulator between the body of the stator and the conductive elements, so that the electrical winding and the body of the stator are excluded from any contact and that a short circuit is thus avoided between the body of the stator and the conductive elements of the electrical winding. The electrical insulation may in particular be in the form of a sheet of insulating paper to which a shape substantially complementary to that of the notch is given. Each notch must therefore be fitted with a sheet of insulating paper.

In order to avoid a tedious and costly assembly operation which would consist of depositing a plurality of sheets of insulating paper independent of each other and respectively in each of the notches, it is known to provide a continuous strip of insulating paper which is capable of being shaped to be housed successively in each of the notches of the stator and against each of the teeth, and in particular against each of the tooth ends arranged on the periphery of the stator body. In a single assembly operation, all of the notches are equipped with a strip of insulating paper which has a slotted shape alternating between positioning facing one end of the tooth and positioning at the bottom of a notch.

The strip thus has a width substantially equal to the axial dimension of the stator body, so that the insulating paper extends over the entire axial dimension of each notch, and a length, between a leading edge and a cutting edge, making it possible to go around the stator by positioning itself successively in the bottom of each notch. In order to optimize the quantity of insulating paper used to produce all the insulating means, and to avoid extra thicknesses of insulating paper in the notches to allow the housing of the conductive elements of the winding, it is planned to dimension the length of the strip of optimally, with the leading edge and the cutting edge ending up in the same notch after the strip has gone around the stator. An overlapping zone, formed by the overlapping of the end of the cutting edge on the end of the leading edge, is thus formed in one of the notches.

It is known to position this overlap zone in the bottom of this notch, opposite the ends of the teeth and the opening through which the conductive elements of the electrical winding are inserted into said notches. The insertion of the conductive elements in the bottom of the notch thus has the effect of pressing the ends of the strip of insulating paper, in the overlap zone, against the bottom wall of the notch and prevents the release of the insulating paper . However, when the insulation is incorrectly positioned initially, it It is possible for the conductors to shift some of the insulation when inserting them into the notches. This can create an area not covered by the insulation and therefore a potential risk of short circuit between the stator body and the conductors.

The present invention aims to address this drawback, namely to avoid the risk of seeing a portion of the notch not covered by insulating paper which could generate a short circuit between the conductive elements of the winding and the body of the stator. A secondary object of the invention is also to be part of a context of optimizing the quantity of insulating paper present in each notch to optimize the costs and the rate of filling of the conductors in the notches in order to improve the overall efficiency. of the machine.

The invention relates to a wound stator comprising at least a body and an electrical insulator, the body comprising at least one yoke which extends around an axis of revolution and a plurality of teeth formed projecting from the yoke, said teeth delimiting two by two a plurality of notches receiving conductive elements of an electrical winding, each of the notches comprising two side walls which extend generally radially and a bottom wall which connects the two side walls, the electrical insulation being arranged in each of the slots between the conductive elements and the corresponding slot walls, the stator being characterized in that at least one of the slots comprises an overlapping region comprising a first layer of electrical insulation which covers a second layer of electrical insulator, the overlap zone being formed against one of the side walls of one of the notches of the body of the stator.

The electrical insulation can, according to an example of the invention, take the form of an electrical insulating sheet arranged between the conductive elements and the walls of the slot, said insulating sheet being able to electrically insulate the body of the stator with respect to to conductive elements. This avoids short circuits between the body of the stator and the conductive elements of the electrical winding. The term first layer of electrical insulation and second layer of electrical insulation is then understood to mean respectively a first insulating sheet and a second insulating sheet which are superimposed on one another. The covering zone is then formed of at least a part of the first insulating sheet, or of the first layer of electrical insulation, which covers at least in part the second insulating sheet, or the second layer of electrical insulation, arranged against one of the side walls of one of the notches of the stator.

Such an overlapping zone is in particular generated by the particular method of winding the stator comprising an installation of the electrical insulation in the stator, said insulation initially taking the form of a continuous strip of electrical insulation. During this method with installation of the electrical insulator in such a form, the continuous strip is successively placed in each of the notches of the stator, with a leading edge which is placed in a notch and with a cutting edge which comes position themselves in this same notch and in such a way that the end of the said continuous strip formed by this cut edge covers an end associated with the leading edge in this notch. The winding method then comprises, once the conductive winding elements have been installed in the notches, a step of cutting out the continuous strip after the insertion of the conductive elements into the notches, at the level of the internal periphery. of the stator body, so that after cutting, a plurality of electrical insulators are formed and in the notch having received the ends of the continuous strip, a first insulating sheet and a second insulating sheet are formed comprising respectively the end end, or cut end, of the continuous strip and the start end, or leading end, of the continuous strip.

Advantage is then taken of the overlap zone according to the invention in that it can be made along a side wall over a greater extent than when it is made in the bottom of the notch. This makes it possible to ensure the existence of a covering, and therefore to ensure that all of the walls delimiting the notch are well covered with electrical insulation, despite the fact that during assembly the layer of electrical insulation may not be exactly at the desired theoretical position due to a plating of the continuous strip which is not perfectly carried out over the entire circumference of the stator body.

According to one characteristic of the invention, the overlap zone is arranged substantially in the center of the side wall of the notch against which it extends, in a radial direction of the stator body. For example, the overlap zone extends away from the radial ends of the side wall. In particular, the overlap zone may extend to a distance from one of the ends of the wall equal to at least 10% of the total radial length of the side wall. This makes it possible to simplify the process of assembling the insulation in the stator by avoiding adding an additional step of holding the portion of insulation which can then be too short to remain in place on its own.

According to a feature of the invention, the overlap zone extends over at least 20% of a radial dimension of the notch.

In this context, the first layer of electrical insulation and the second layer of electrical insulation can extend over all or part of the radial dimension of this side wall, from when the radial dimension of the overlap zone that they participate in forming is equal to at least 20% of the corresponding radial dimension of the notch. By radial dimension of the notch, as of the side wall, is meant a dimension taken from an opening of the notch on the internal periphery of the stator body to its bottom wall, in the radial direction of the stator body. . Such an overlap zone which extends over at least 20% of the radial dimension of the notch makes it possible to ensure that, even in the event of a one-time defect in the plating of the strip of electrical insulation against the body of stator during the winding process, there is sufficient covering of the side wall of the notch by electrical insulation so as to avoid having portions of the stator not covered by insulation and short- circuits between the conductive elements and the stator body. In other words, a radial dimension of the overlap zone of at least 20% of the radial dimension of the notch corresponds to a minimum overlap threshold which ensures sufficient overlap of the side wall in order to avoid short circuits between the conductive elements and the stator, and more particularly the stack of laminations participating in forming the stator body, whatever the assembly clearances. In this context, the overlap zone can in particular extend against the side wall radially over at least 4 mm.

In a complementary manner, the overlap zone can extend over a portion of the side wall that is less than 50% of a radial dimension of the notch or extend over the entire radial dimension of the side wall. In one case, a maximum dimension of overlap is provided, such an overlap of the side wall of the notch between 20% and 50% of the radial dimension of the notch representing an interesting compromise between the fact of limiting the quantity of insulation to be used and the fact of ensuring reliable electrical insulation between the stator body and the conductive elements.

According to one characteristic of the invention, the first layer of electrical insulation extends only along at least a portion of the side wall against which the covering zone is formed.

According to a characteristic of the invention, the first layer of electrical insulation has an end edge disposed at a non-zero distance from the bottom wall of the notch.

According to one characteristic of the invention, the first layer of electrical insulation extends from an opening of the notch arranged radially opposite the bottom wall. The first layer of electrical insulation, during the installation operation of the electrical insulation, may have an end edge facing the bottom wall and which therefore tends to be pressed against the side wall during the installation. insertion of conductive elements rather than being brought back to the center of the notch.

According to one characteristic of the invention, the second layer of electrical insulation which is at least partly covered extends continuously along the side wall against which the covering zone is formed, of the bottom wall of the notch and the other side wall. More particularly, the second layer of electrical insulation substantially forms a U-shape whose base is positioned against the bottom wall of the notch and therefore the branches extend along the side walls. This shape may be asymmetrical in that the second layer of electrical insulation extends over the entire radial dimension of the other side wall, namely the side wall opposite the overlap zone, while the second layer of electrical insulation may extend only over part of the side wall against which the overlap zone is formed. It is then understood that the second layer of electrical insulation, which extends over three walls of the notch, covers a larger surface of the walls of the notch than the first layer of electrical insulation, which extends only over a side wall.

Alternatively, the shape of the second layer of electrical insulation can be symmetrical, in particular U-shaped.

According to a feature of the invention, the second layer of electrical insulation extends along the side wall against which the overlap zone is formed, from the bottom wall of the notch, and the first layer of insulation electric extends along this same side wall from the inner periphery of the stator body. This allows complete covering, while being able to reduce the quantity of insulation used, of the side wall against which the covering zone is formed, and it is possible, by combining this characteristic with the continuous arrangement of the second layer of insulation against the side walls and the bottom wall of the notch, full covering of the side walls and of the bottom wall of the notch in which the covering zone is formed, by the first layer of electrical insulation and/ or by the second layer of electrical insulation.

According to a characteristic of the invention, a thickness of each of the layers of electrical insulation is between 0.1 mm and 0.3 mm. It is then understood that the overlap zone has a thickness of between 0.2 mm and 0.6 mm.

According to a characteristic of the invention, the insulator is arranged in the notch so as to form an opening. Said opening being able to be arranged at the level of the notch opening.

According to one characteristic of the invention, the stator comprises several notches comprising each an overlap zone Alternatively, the stator comprises a single notch comprising an overlap zone.

According to one characteristic of the invention, the notches, distinct from the notch or notches in which the overlap zone is arranged, each comprise a regular thickness of electrical insulation against each of the walls delimiting these notches, the electrical insulation being distributed against the side walls and the bottom wall in a single continuous layer of electrical insulation.

Such a characteristic stems in particular from the particular mounting method of the electrical insulation in the notches of the stator, the latter being initially present in the form of the continuous strip mentioned above. Thus, only the notch in which the leading end and the cutting end of the continuous strip meet locally has a double thickness of electrical insulation, between 0.2mm and 0.6mm according to the example with figures previously mentioned, formed by the superposition of the first layer of electrical insulation and the second layer of electrical insulation, the other notches having a single layer of electrical insulation, with a thickness of between 0.1mm and 0.3mm according to the example with figures mentioned above, without an overlap zone.

According to a feature of the invention, the slots of the stator comprise tooth roots, each extending circumferentially from an associated tooth end. Alternatively, the slots of the stator have no tooth root.

The invention may also relate to a method for winding a stator according to any one of the preceding characteristics, during which, in a first step, a continuous strip of electrical insulation is placed in each of the notches of the body of the stator and against each of the tooth ends arranged between the notches such that a leading end of the continuous strip is covered by a cutting end of the continuous strip in one of the notches and along one of the side walls of this notch, during which, in a second step, conductive elements of the winding are inserted into each of the notches.

For example, the method can comprise a third step, once the conductive elements of the winding have been inserted into the notches, where parts of the continuous strip are cut, forming connection parts arranged opposite each of the ends of the teeth. This makes it possible to avoid any friction between the rotor and the insulation and to avoid a reduction in the air gap between the rotor and the stator. It is understood that at the end of the process, the electrical insulation initially in the form of a continuous strip is separated into a plurality of independent sheets from one notch to another, with the electrical insulation in the notch comprising the overlapping zone which is found formed by two distinct sheets within the same notch. The position of the overlap zone against a side wall and the configuration of the two sheets participating in forming this overlap zone makes it possible to ensure, during the insertion of the conductive elements, that the sheets are pressed against this side wall, and that the overlap zone is maintained laterally in its theoretical position. The extra thickness created in the overlap zone by the superimposition of the two sheets allows the insertion of the conductive elements into the notch and promotes the immobilization of the insulation against the side wall once the conductive elements are in place, which allows also to ensure that the overlap zone is maintained laterally in its theoretical position during the cutting operation of the connecting parts in the last step of the method.

For example, the cut end faces a bottom wall of the notch.

The invention also relates to a rotating electrical machine comprising at least one wound stator according to any one of the preceding characteristics and at least one electrical winding which comprises conductive elements respectively housed in the notches of the wound stator.

Other characteristics, details and advantages of the invention will emerge more clearly on reading the description given below by way of indication in relation to the drawings in which:

[Fig 1] is a general partial exploded perspective view of a rotating electrical machine according to the invention;

[Fig 2] is a perspective view of a stator of the rotating electrical machine of Figure 1 comprising at least one electrical winding;

[Fig 3] is a top view of the stator of Figure 2, without the electrical winding, making more particularly visible a plurality of notches formed in a body of the stator;

[Fig 4] is a detail view of two successive notches of the stator of Figure 3, each notch being delimited by walls against which extends an electrical insulator, a notch comprising more particularly a first layer of electrical insulation and a second layer of electrical insulation forming an overlap zone; [Fig 5] is a detail view of the notch of Figure 4 comprising an overlap zone of two layers of electrical insulation, said notch being here filled with conductive elements of the electrical winding;

[Fig 6] is a schematic representation of a continuous strip of electrical insulation used to form the electrical insulators present in the notches, the continuous strip being shown in its original shape, then in the crenellated shape allowing it to be put in place against the walls of the slots of the stator of figure 2.

It should first be noted that if the figures expose the invention in detail for its implementation, these figures can of course be used to better define the invention, if necessary. It should also be noted that these figures only show exemplary embodiments of the invention. Finally, the same references designate the same elements in all the figures.

As a reminder, the invention relates to a particular arrangement of an electrical insulator housed in the body of a stator so as to avoid short circuits between the metallic body of this stator and an electrical winding associated with this stator. The invention, which will be described in more detail below, is particularly applied in rotating electrical machines such as that illustrated in Figure 1.

FIG. 1 illustrates an exploded view of a rotating electrical machine 1, which can for example be used within a vehicle such as a motor vehicle or a drone in an application of the alternator-starter type, alternator, reversible machine or electric motor. When operating in an alternator mode, the rotating electrical machine 1 transforms mechanical energy into electrical energy and when operating in motor mode, it transforms electrical energy into mechanical energy.

To this end, the rotary electrical machine 1 comprises, inside a casing 2 here formed of two shells able to be fitted against one another, a rotor/stator assembly. More specifically, the rotor/stator assembly, here with an internal rotor, comprises a stator 8, which is equipped with an electrical winding 24 capable of being connected by a suitable connector 25 to an electrical network via a voltage converter, not illustrated. here, and a rotor 3 capable of rotating inside the stator and secured to a shaft 4 which extends along an extension axis X. The rotor 3 comprises magnetic elements, for example an electric winding, capable to interact with a rotating magnetic field created by the power supply of the winding. Alternatively, the rotor can include magnetic magnets to generate the magnetic field or even be a squirrel cage rotor.

The stator 8, more particularly visible in Figures 2 and 3, comprises a body 12 formed by a stack of laminations stacked against each other along an axis of revolution R of the stator, parallel to the axis of extension X of the previously mentioned rotating electrical machine. In the remainder of the description, the terms radial, axial and interior/exterior refer to the axis of revolution R of the stator 8.

The body 12 of the stator 8 comprises at least one yoke 14 which extends around the axis of revolution R of the stator 8, and projecting from which is formed a plurality of teeth 16, visible in FIG. 3. Each tooth 16 extends radially towards the axis of revolution of the stator and the free end of each of the teeth, forming a tooth end 20 facing the inside of the stator, participates in delimiting an internal periphery 18 of the body 12 of the stator. The plurality of teeth 16 also makes it possible to delimit a plurality of notches 22 in pairs. More specifically, two adjacent teeth 16 make it possible to delimit a notch 22 of the stator body, each of the notches being intended to receive conductive elements 24a d an electrical winding 24 of the stator 8 as shown in Figure 2.

The notches 22, more particularly visible in FIGS. 4 and 5, each comprise two side walls 26 which extend radially and a bottom wall 28 which connects the two side walls 26 at the level of the yoke 14. The notches 22 are open towards inside the stator body so that they each have an opening 30 at the inner periphery 18 of the stator body 12, opposite the bottom wall 28. The opening 30 of each of the notches 22 makes it possible to insert the conductive elements 24a of the electrical winding 24, in the radial direction of the stator.

These conductive elements 24a pass axially through the stator and can be arranged in radial alignment within the slot, the ends of these conductive elements being connected to the ends of conductive elements passing axially through the stator in another slot so as to form a continuous winding. These conductive elements can, without this being limiting of the invention, consist of a portion of a continuous conductive wire wound around the teeth, or of rigid segments whose ends are welded to the ends of other rigid segments. The electric machine 1 also comprises an electrical insulator 32, intended to be placed between the conductive elements 24a of the winding and the walls 26, 28 of the teeth of the stator delimiting the notches, as can be seen in particular in FIG. 5.

The electrical insulator 32 is according to the invention formed of a plurality of sheets of insulating paper respectively arranged in each of the notches 22 of the stator body. More particularly, in each of the notches, at least one layer of electrical insulation 34 is placed between the conductive elements 24a and the side walls 26 and the bottom wall 28 delimiting these notches 22 and a sheet of insulating paper forms this layer of electrical insulator 34.

According to the invention, one of the notches 22 of the plurality of notches 22 is particular in that the electrical insulator 32 housed therein is formed of several layers of electrical insulation, while the other notches comprise a single layer of electrical insulation. In figures 4 and 5, a small number of notches are shown but it should be noted that only one notch is different from the others regarding the arrangement of the electrical insulation in this example.

It should be understood that in FIG. 4, the sheets of insulating paper respectively arranged in each of the notches, and forming the at least one layer of electrical insulation 34, are connected by connection portions 35 participating in forming with the sheets of paper a continuous strip which is, according to an assembly method which will be described later, shaped to be placed in one operation in each of the notches. These connection portions are removed once the conductive elements 24a are arranged within the notches, to achieve a configuration visible in Figure 5.

As mentioned, the notches, distinct from the notch in which the covering zone 36 is formed, each comprise a single layer of electrical insulation 34c forming a regular thickness of electrical insulation 32 distributed against the side walls 26 and the bottom wall of the notches 22. In other words, each of the notches 22 not including the overlap zone 36 comprises a single insulating sheet which extends against its side walls 26 and its bottom wall 28, and which has emerges a substantially symmetrical U-shape with two branches which extend over the entire radial dimension of the corresponding notch, namely from the bottom wall to the opposite opening.

As mentioned, one of the notches 22 of the plurality of notches 22 is special in that the electrical insulator 32 housed therein is formed of several layers of electrical insulation. More particularly, this particular notch comprises an overlap zone 36 comprising a first layer of electrical insulation 34a which at least partly covers a second layer of electrical insulation 34b, the overlap zone 36 being formed against one of the side walls 26 of the notch 22 in which said overlap zone 36 extends.

As can be seen in FIG. 5, once the connection portions have been cut out, the first layer of electrical insulation 34a is a first insulating sheet and the second layer of electrical insulation 34b is a second insulating sheet, distinct from the first insulating sheet and pressed against the latter.

The first layer of electrical insulation 34a extends only facing the side wall against which the overlap zone is formed. More particularly, this first layer of electrical insulation 34a extends from the opening 30 of the corresponding notch to the overlap zone and has an end edge 37 placed at a non-zero distance D from the bottom wall 28, along the radial direction of the stator. At least a part of this first layer of electrical insulation 34a covers at least a part of the second layer of electrical insulation 34b, which extends directly against the side wall 26 against which the covering zone 36 is formed.

The second layer of electrical insulation 34b, which is at least partly covered by the first layer of electrical insulation 34a in order to form the covering zone 36, extends continuously over each of the walls delimiting the notch, namely along the side walls 26 and the bottom wall 28 of said notch 22. More particularly, the second layer of electrical insulation 34b extends at least partially over the radial dimension of the side wall of the notch against which is formed the overlap zone 36, then is extended so as to extend against the bottom wall of the notch, then is further extended so as to extend over the entire radial dimension of the other side wall, from the bottom wall 28 as far as the opening 30. This second layer of electrical insulation 34b thus has a U-shape, the base of which is positioned against the bottom wall 28 and the branches of which extend along the walls 26. As shown , this U-shape can be asymmetrical when the overlap zone is such that the second layer of electrical insulation extends only over part of the side wall against which the overlap zone is formed.

In this way, the walls delimiting the notch 22 in which the overlap zone 36 is formed are completely covered by a single thickness of insulating layer. formed by the first layer of electrical insulation 34a or by the second layer of electrical insulation 34b or by, in the overlap zone, a double thickness of layer of insulation by the superposition of the two layers of electrical insulation 34a, 34b . Integral electrical insulation is thus ensured between the notch 22 which includes the overlap zone 36 and the conductive elements 24a of the electrical winding 24 housed in this notch.

It follows from the arrangement according to the invention of the overlap zone 36 against a side wall 26 of the notch that one of the two layers of insulation present in this notch, here the first layer of electrical insulation 34a has the shape of a flat sheet, facing a single side wall, and that the other layer of insulation, here the second layer of electrical insulation 34b, has the shape of a U-shaped sheet, facing each walls delimiting the notch. Advantageously, it is the layer of insulation having the shape of a flat sheet which comes to cover one of the branches of the U formed by the other layer of insulation. This can be explained in particular with reference to FIG. 4, which illustrates the arrangement of the overlap zone before the insertion of the conductive elements 24a of the winding. The insulation layer having the shape of a flat sheet, here the first electrical insulation layer 34a, extends in the continuity of a connection portion, forming a cut-off end edge of the continuous strip previously mentioned, so that it has a free end edge facing the bottom of the notch. The other layer of insulation, here the second layer of electrical insulation 34b, extends in the continuity of the other connection portion adjacent to the notch but extends along a first side wall and the bottom wall before rising along the side wall against which the overlap zone 36 is formed, in the direction of the opening 30, so that it also has a free end edge, forming an edge of leading end of the continuous strip previously mentioned, but which faces the opening. An arrangement according to that of the example of Figure 4, with the first layer of electrical insulation, namely the insulation layer extending only along a side wall, which covers the second layer of electrical insulation, namely the layer of insulation extending over all the walls delimiting the notch, makes it possible to simplify the fact that the insertion of the conductive elements 24a of the electrical winding into the notch will tend to flatten the parts of the layers of insulation forming the overlap zone against the corresponding side wall. It is understood that an inverse arrangement, with the second layer of electrical insulation covering the first layer of electrical insulation, would imply the presence of a free end edge of this second layer of insulation facing the opening and likely to be pushed towards the wall background when inserting the conductive elements. It would then be possible to add a holding element to hold the second layer of electrical insulation during the insertion of the conductors. Another alternative could be to have the second layer of electrical insulation which covers the end of the tooth carrying the covering zone.

As may have been mentioned previously, each of the layers of electrical insulation 34, namely the first layer of electrical insulation 34a or the second layer of electrical insulation 34b arranged in the notch which includes the overlap zone 36 and the single layer of electrical insulation 34c of the notches 22 not comprising any overlap zone, is obtained from a continuous strip of insulating paper, for example the thickness of each layer may be the same. The thickness of each of the layers of electrical insulation 34 is taken along a straight line perpendicular to the side wall 26 and/or the bottom wall 28 against which this layer of electrical insulation 34 extends. is here between 0.1mm and 0.3mm. It is then understood that the overlap zone 36 has a thickness of between 0.2 mm and 0.6 mm.

The overlap zone 36 of the notch 22 extends over at least 20% of a radial dimension of the notch 22 taken from the opening 30 of the notch 22 to its bottom wall 28, according to the radial direction of the stator body.

In other words, the part of the first layer of electrical insulation 34a and the part of the second layer of electrical insulation 34b which forms the overlap zone 36 each extend over at least 20% of the radial dimension of the notch. 22, it being understood that if one of the layers of insulation has an extent only equal to this minimum value of 20% of the radial dimension of the notch 22, the other layer of insulation must extend over the entire radial dimension of the notch so that the overlapping area can extend over at least 20% of the radial dimension of the notch 22.

Such an overlap zone 36 corresponding to at least 20% of the radial dimension of the notch 22 provides an overlap zone 36 sufficient to limit short circuits between the conductive elements and the notch 22, in particular due to mounting clearances electrical insulation 32 in the stator. The winding process and the particular installation of the electrical insulator 32 in the body of the stator will be detailed later in the following description.

The radial extent of each layer of insulation forming the overlap zone may furthermore be such that the overlap zone extends up to 50% of the radial dimension of the notch, it being understood that a larger dimensioning of the overlap zone is to be avoided for the dual purpose of saving insulating paper and limiting the areas of extra thickness in the notch so as not to interfere with the insertion of the conductive elements .

In the example more particularly illustrated in FIGS. 4 and 5, the overlap zone 36 extends substantially at the center of the side wall 26 of the notch 22 against which it extends, in the radial direction of the stator body. . Such an arrangement of the overlapping zone 36 in the notch 22 allows the overlapping zone 36 to be held in optimum position during the insertion of the conductive elements into the said notch 22 in the radial direction of the stator body.

We will now describe in more detail a possible method of winding the stator and more particularly the installation of the electrical insulator 32 in the notches of the stator.

As mentioned, the layers of insulation are arranged in the notches in a single continuous installation operation, the layers of insulation forming with connecting portions 35, then intended to be cut and removed, a continuous strip 38.

The continuous strip 38 of electrical insulation 32 is made of a material capable on the one hand of providing both electrical insulation between two elements, here the stack of laminations forming the stator body and the conductive elements 24a of the winding electric 24, and on the other hand to be sufficiently flexible so that the strip 38 can be shaped in a succession of crenellations suitable for being inserted successively into each of the notches 22. FIG. 6 illustrates the deformation imposed on the continuous strip 38, at the plane origin, so that it is likely to be housed in the notches. FIG. 6 also illustrates that the continuous strip, in its planar arrangement, has at least one start end 40 and an opposite cut end 42 along the main direction of elongation of the continuous strip 38, and that these ends are intended to be superposed on one another to form according to the invention the overlap zone in one of the notches.

The winding process more particularly comprises a first step during which the continuous strip 38 of electrical insulation 32 is placed inside the stator in each of its notches 22, with the connection portions which are found against each of the ends of teeth 20 arranged between the notches, as is particularly visible in FIG. 4. The dimension of the continuous strip 38 is such that the leading end 40 and the cutting end 42 are in the same notch 22 and such that these ends 40, 42 form the overlap zone 36. For example, in this notch 22, the start end 40 of the continuous strip 38 being covered by the cut end 42 of the continuous strip 38 in said notch 22.

In order to achieve the example of arrangement of FIG. 4 previously mentioned, the continuous strip 38 is more particularly installed in the stator body in such a way that the start end 40 of the continuous strip 38 is arranged along a side wall being turned towards the opening 30 of the notch 20, and that this start end is covered by the cut end 42 of the continuous strip 38, which is turned towards the bottom wall 28 of notch 22.

In other words, the leading end 40 of the continuous strip 38 is disposed along a side wall of a notch and the continuous strip 38 is then directed towards the bottom wall then the opposite side wall of this notch, before extending successively into each of the notches and returning to the initial notch, with the start end which is covered by the cut end 42 of the continuous strip 38, which is then turned towards the bottom wall 28 of the notch 22.

Subsequently, during a second step, the conductive elements 24a of the electrical winding 24 are inserted into each of the notches 22 of the stator body in the radial direction of the latter, so that the continuous strip 38 and the zone covering 36 are pressed by the conductive elements 24a against each of the walls 26, 28 of the notches 22 as can be seen in FIG. 5. Once the conductive elements 24a are installed in the notches 22, the winding method comprises, in a third step, a cutting operation of the connection parts 35 of the continuous strip 38 arranged opposite each of the ends of the teeth 20. As mentioned, at the end of this third step, the previously continuous strip is separated into a plurality of layers of electrical insulation 34 in each of the notches 22 of the stator. We find, in the notch 22 comprising the overlap zone 36, the first layer of electrical insulation 34a and the second layer of electrical insulation 34b which each respectively comprise the cut-off end 42 of the continuous strip 38 and the start end 40 of the continuous strip 38. And we find in each of the other notches, having no overlap zone, the single layer of electrical insulation 34c.

The wound stator as just described makes it possible, by simple means, to ensure optimum electrical insulation between conductive elements of an electrical winding and a stator body. The invention as it has just been described cannot however be limited to the means and configurations exclusively described and illustrated, and also applies to all equivalent means or configurations and to any combination of such means or configurations. For example, it will not be departing from the scope of the invention by using several strips of insulating paper and by proposing a stator having several notches presenting an overlapping zone and thus several overlapping zones on the circumference of the stator.

Claims

1. Wound stator (8) comprising at least one body (12) and an electrical insulator (32), the body (12) comprising at least one yoke (14) which extends around an axis of revolution (R) and a plurality of teeth (16) projecting from the yoke (14), said teeth (16) delimiting two by two a plurality of notches (22) receiving conductive elements (24a) of an electric winding ( 24), each of the notches (22) comprising two side walls (26) which extend generally radially and a bottom wall (28) which connects the two side walls (26), the electrical insulator (32) being disposed in each of the notches (22) between the conductive elements (24a) and the walls (26, 28) of the corresponding notch (22), the stator (8) being characterized in that at least one of the notches (22) comprises an overlap area (36) comprising a first layer of electrical insulation (34a) which overlies a second layer of electrical insulation (34b), the overlap area (36) being t formed against one of the side walls (26) of one of the notches (22) of the stator body (14).

2. Stator (8) wound according to the preceding claim, wherein the overlap zone (36) extends over at least 20% of a radial dimension of the notch (22).

3. Stator (8) wound according to any one of the preceding claims, in which the overlap zone (36) extends over a portion of the side wall (26) less than 50% of a radial dimension of the notch (22) or extending the full radial dimension of the side wall.

4. Stator (8) wound according to any one of the preceding claims, in which the second layer of electrical insulation (34b) extends along the side wall (26) against which the overlap zone (36) is formed. ), from the bottom wall (28) of the notch, and the first layer of electrical insulation (34a) extends along this same side wall (26) from an opening (30) of the notch arranged radially opposite the bottom wall (28).

5. Stator (8) wound according to any one of the preceding claims, wherein the first layer of electrical insulation (34a) extends only along at least a portion of the side wall (26) against which is formed the overlap zone (36).

6. Stator (8) wound according to any one of the preceding claims, in which the first layer of electrical insulation (34a) has an end edge (37) disposed at a non-zero distance (D) from the wall of the bottom (28) of the notch (22).

7. Stator (8) wound according to any one of the preceding claims, in which the second layer of electrical insulation (34b) which is at least partly covered extends from continuously along the side wall (26) against which the overlap area (36) is formed, the bottom wall (28) of the notch and the other side wall (26).

8. Stator (8) wound according to any one of the preceding claims, in which the notches (22), distinct from the notch (22) in which the overlap zone (36) is arranged, each comprise a regular thickness d electrical insulation (32) against each of the walls delimiting these notches, the electrical insulation being distributed against the side walls (26) and the bottom wall (28) in a single layer of electrical insulation (34c).

9. Stator (8) wound according to any one of the preceding claims, wherein a thickness of each of the layers of electrical insulation (34a, 34b, 34c) is between 0.1mm and 0.3mm.

10. Rotary electric machine (1) comprising at least one stator (8) wound according to any one of the preceding claims and at least one electric winding (24) which comprises conductive elements (24a) respectively housed in the notches (22) of the wound stator (8).