EP4005064A1

EP4005064A1 - Stranded conductor with adhesive

Info

Publication number: EP4005064A1
Application number: EP20754339.8A
Authority: EP
Inventors: Cyril Moya
Original assignee: Nidec PSA Emotors SAS
Current assignee: Nidec PSA Emotors SAS
Priority date: 2019-07-26
Filing date: 2020-07-23
Publication date: 2022-06-01
Also published as: FR3099284A1; FR3099284B1; WO2021019158A1

Abstract

Electrical conductor, in particular in the form of a U-shaped or I-shaped pin, intended to be inserted into the notches (21) of a stator (2) of an electrical rotating machine (1), the electrical conductor (22) comprising a plurality of strands (32), at least one strand being flat, at least one of the strands being at least partially or completely covered with a layer of an adhesive material, in particular a thermo-adhesive material (321), the strand(s) (32a) which are at least partially or completely covered with a layer of adhesive material (321) being arranged between two strands (32b, 32b') which do not have such a layer.

Description

Title: Multi-stranded conductor with member

The present invention claims the priority of French application 1908564 filed on July 26, 2019, the content of which (text, drawings and claims) is incorporated here by reference. The present invention relates to an electrical conductor intended to be inserted into a stator of a rotating electrical machine.

Technical area

The invention relates more particularly to synchronous or asynchronous machines with alternating current. It relates in particular to traction or propulsion machines for electric motor vehicles (Battery Electric Vehicle) and / or hybrids (Hybrid Electric Vehicle - Plug-in Hybrid Electric Vehicle), such as passenger cars, vans, trucks or buses. The invention also applies to rotating electrical machines for industrial and / or energy production applications, in particular naval or wind turbines or aeronautics.

Prior art

Electrical machines used in automotive applications can include conductors having parallel strands. An example of such a conductor is described in application GB 2 030 375.

The production of electrical conductor with hairpin and parallel strands and their insertion into a stator of a rotating electrical machine is complex. Indeed, it is necessary to position the electrical conductors one by one on a mask before inserting them into the stator. The implementation of this method is relatively long and may require the use of a significant number of tools, in particular to be able to adapt to each form of pin. This method of producing a stator also requires a large floor area to position the machines, which can complicate manufacturing.

Another drawback associated with the use of an electrical conductor with parallel strands is the risk of the strands of the electrical conductor bulging in the notches of the stator. This expansion complicates the assembly of the stator and may require increasing the various dimensions. In addition, the proliferation of strands of an electrical conductor complicates the alignment of the electrical conductor with the notch in which it is to be inserted.

There is a need to facilitate the insertion of electrical conductors into the notches of a stator of a rotating electrical machine and to limit the proliferation of the strands of the electrical conductors. Disclosure of the invention

The invention aims to meet this need and it achieves it, according to one of its aspects, thanks to an electrical conductor, in particular in the shape of a U or I pin, intended to be inserted into the notches of a stator of a rotating electrical machine, the electrical conductor comprising several strands, at least one strand being flat, at least one of the strands being covered at least partially, or even completely, by a layer of an adherent material, in particular heat-adherent.

By "strand" we mean the most basic unit for electrical conduction. The strands are preferably made from an electrically conductive material such as copper or aluminum. Each strand can be coated with an insulating material. The insulating material is for example an enamel. In the case where the strand is coated with an insulating material, the layer of adherent material is applied over the layer of insulating material.

By "adherent material" is meant a material capable of polymerizing and thus acquiring adhesive properties.

In one embodiment, the adherent material is a heat adherent material. By "heat-adherent material" is meant a material capable of polymerizing under the action of heat and thus acquiring adhesive properties.

The adherent material, in particular heat-adherent, can in particular be chosen from the following list, which is not limiting: polyester, polyamide, polyvinylbutyral, epoxy polymer. The thermo-adherent material may be an insulating varnish of temperature class B or F, and or preferably H or C. The strand covered with adherent material, in particular thermo-adherent, perhaps of grade GR1, GR2 or GR3. The term “grade” is understood to mean the number of layers of adherent material which covers the strand. For example, a GR1 grade strand is covered with one layer of adherent material, a GR2 grade strand is covered with two layers of adherent material, and a GR3 grade strand is covered with three layers of adherent material. The grade of the strands and the temperature class of the adherent material can be chosen according to the operating voltage of the electrical machine and / or the environment such as, for example, outdoor humidity or the salinity of the air.

Preferably, the adherent material is visible to the naked eye or by a suitable detection method, for example using black light.

A flattened strand may have a substantially rectangular cross section. The strand covered at least partially, or even completely, by a layer of an adherent material may be flat, for example being of substantially rectangular cross section. All the strands covered with a layer of an adherent material may have a substantially rectangular cross section, or even all the strands present in the notch. As a variant, a majority of the strands may have a substantially rectangular cross section. As a further variant, a minority of the strands may have a substantially rectangular cross section.

The thickness e of a strand is defined as the smallest dimension of the cross section of the strand. It corresponds to the dimension of the strand in the radial direction of the machine. The width 1 of a strand is defined as the largest dimension of the cross section. It corresponds to the dimension of the strand in the circumferential direction around the axis of rotation of the machine.

The term “covered” is understood to mean that a layer of adherent material, in particular thermo-adherent material, has been deposited over at least part of the outer surface of one strand of the electrical conductor, when the latter is observed in cross section. . For example, dots and / or strips of adherent material, in particular heat-adherent, can be deposited on the outer surface of a strand of an electrical conductor.

As a variant, the adherent material, in particular thermo-adherent, can be deposited on the entire outer surface of a strand of the electrical conductor, when the latter is observed in cross section.

As a further variant, the strand may include at least one face covered with a layer of adherent material. The other face (s) of the strand may be devoid of a layer of adherent material.

The use of electrical conductors according to the invention in a stator of a rotating electrical machine makes it possible to limit the risk of the strands of an electrical conductor bulging. In addition, the rigidity of the electrical conductors is improved. Their insertion into the notches of the stator is thus facilitated.

The use of electrical conductors according to the invention further improves the filling rate of the notches. It is thus possible to reduce the size of the notches. The notches can be dimensioned as closely as possible to the size of the electrical conductors.

The use of electrical conductors according to the invention provides better thermal conductivity to the stator. In addition, the ends of the conductors to be soldered are more easily located.

Finally, the floor area required for winding the stator and for manufacturing the electrical machine is reduced. Another subject of the invention, according to another of its aspects, is an electrical conductor, in particular in the form of a U-shaped or I-shaped pin, intended to be inserted into the notches of a stator of a rotating electrical machine, the electrical conductor comprising several strands, at least one strand being flat, at least one of the strands being covered at least partially, or even completely, by a layer of an adherent material, in particular thermo-adherent,

the strand or strands covered at least partially, or even completely, with a layer of adherent material being placed between two strands without such a layer.

Another subject of the invention, according to another of its aspects, is an electrical conductor, in particular in the form of a U-shaped or I-shaped pin, intended to be inserted into the notches of a stator of a rotating electrical machine, the electrical conductor comprising several strands, at least one strand being flat, at least one of the strands being covered by a layer of insulating material and at least partially, or even completely, by a layer of an adherent material, in particular heat-adherent,

the layer of adherent material being applied over the layer of insulating material. Advantageously, the strand or strands covered at least partially, or even completely, with a layer of adherent material can be placed between two strands without such a layer.

For example, if the electrical conductor has three strands, the middle strand is covered with an adhesive layer and the other two strands do not have such a layer.

Alternatively, if the electrical conductor has five strands, the central strand and the end strands are devoid of a layer of adherent material, and the other two are covered with a layer of adherent material.

In the case where the adherent material, in particular heat-adherent, is deposited on the entire outer surface of a strand of the electrical conductor, when the electrical conductor according to the invention is observed in cross section, the faces other than those in contact with an adjacent strand are covered with a layer of adherent material. It is thus possible to determine on the stator on which strands the adherent material has been applied beforehand. In one embodiment, when moving along a radial axis of the machine, every second strand may be covered with a layer of adherent material

Alternatively, the strand closest to and the strand furthest from the axis of rotation of the machine may be devoid of a layer of adherent material. All the other strands between the strand closest to and the one furthest from the axis of rotation of the machine can be covered with a layer of adherent material. Alternatively, the strand closest to and the strand furthest from the axis of rotation of the machine may be devoid of a layer of adherent material and every other strand between the strand closest to and the strand furthest from it. The axis of rotation of the machine can be covered with a layer of adherent material.

In one embodiment of the invention, all of the strands of an electrical conductor can be covered at least partially, or even completely, with a layer of adherent material. In one embodiment of the invention, every other strand may be covered at least partially, or even completely, with a layer of adherent material. For example, in the case where the conductor has three strands, the central strand is devoid of a layer of adherent material and the other two are covered with it.

Advantageously, one of the strands of an electrical conductor according to the invention may include a contact face with an adjacent strand, this face possibly being at least partially covered with a layer of adherent material.

The layer of adherent material is, for example, at the interface between two strands. The term "proximal face of a strand" denotes the face of a strand closest to the axis of rotation of the machine. The term "distal face of a strand" is used to designate the face of a strand furthest from the axis of rotation of the machine.

In one embodiment, all of the strands have a face covered with a layer of adherent material. It can be the distal face or alternatively the proximal face.

As a variant, a predefined number of strands have at least one face, in particular two opposite faces, covered with a layer of adherent material. In particular, every second strand in the electrical conductor comprises at least one, in particular two opposite faces, covered with a layer of adherent material.

Preferably, the layer of adherent material is applied to a face corresponding to a large side of the cross section. Alternatively, the layer of adherent material is applied to a face corresponding to a short side of the cross section.

A layer of adherent material can be applied only to the proximal faces of the strands. Alternatively, a layer of adherent material can be applied only to the distal faces of a strand. As a further variant, a layer of adherent material can be applied to the distal faces of some strands and to the proximal faces of other strands. Alternatively, the layer of adherent material may be present on two, or three or four sides of each strand when viewed in cross section.

Advantageously, the cross section of said at least one strand covered with a layer of thermo-adhesive material can be substantially rectangular. Advantageously, the layer of adherent material may have a thickness c of between 0.05 mm and 0.2 mm, better still between 0.07 mm and 0.15 mm, being for example 0.1 mm.

The thickness c of the layer of adherent material covering a strand is measured before the strands are assembled to form an electrical conductor.

The thickness c of the layer of adherent material may be constant over the entire outer surface of the strand or strands covered with the electrical conductor.

As a variant, the thickness c of the layer of adherent material can be variable.

Winding

The electrical conductors can form a single coil, in particular whole or fractional. By "single winding" is meant that the electrical conductors are electrically connected together in the stator, and that the connections between the phases are made in the stator, and not outside the stator, for example in a terminal box. .

The electrical conductors can form a distributed coil. The winding is not concentrated or wound on tooth.

The winding is in the invention whole or fractional. The winding can be full in pitch with or without shortening, or in a fractional variant. In one embodiment, the electrical conductors form a fractional coil, in particular with a shortened pitch. The number of notches in the stator can be between 18 and 96, better still between 30 and 84, being for example 18, 24, 27, 30, 36, 42, 45, 48, 54, 60, 63, 72, 78 , 81, 92, 96, better still being 60 or 63. The number of poles of the stator can be between 2 and 24, or even between 4 and 12, being for example 6 or 8.

The winding can have a single winding path or several winding paths. In an "electrical conductor" flows the current of the same phase by winding. By "winding path" is meant all the electrical conductors of the machine which are traversed by the same electric current of the same phase. These electrical conductors can be connected to each other in series or in parallel or in series-parallel. In the case where there is only one channel, the electrical conductors are connected in series. In the case where there are several channels, the electrical conductors of each channel are connected in series, and the channels are connected in parallel.

Electric conductors

In an "electrical conductor" flows the current of the same phase of a winding track. Several electrical conductors in series form a "coil". The number of coils per phase is at most equal to the number of stator poles or to the number of pole pairs. In each notch there can be one or more layers. The term “layer” denotes the electrical conductors in series belonging to the same phase arranged in the same notch. In each layer of a notch, there are the electrical conductors of the same phase. In general, the electrical conductors of a stator can be distributed in one layer or in two layers. When the electrical conductors are distributed in a single layer, each notch only accommodates electrical conductors of the same phase.

In the invention, the electrical conductors can be divided into only two layers. In this case, one or more notches can house electrical conductors of two different phases. This is always the case for a short pitch winding. In one embodiment, the coil may not have more than two layers. In one embodiment, it is notably devoid of four layers.

At least a first electrical conductor housed in a first notch can be electrically connected to a second electrical conductor housed in a second notch, at the outlet from said notches.

By "electrically connected" is meant any type of electrical connection, in particular by welding, with different possible welding methods, in particular laser, tungsten electrode (in English "Tungsten Inert Gas" or TIG), induction, friction, ultrasound, vibrations , or brazing, or by mechanical clamping, in particular by crimping, screwing or riveting for example.

The first and second notches are preferably non-consecutive.

The first and second electrical conductors can be electrically connected to the output of the first and second notches, that is to say that the electrical connection is formed on the electrical conductors just after their exit from the two notches, at an axial end of the stator mass. The electrical connection can be made in a plane perpendicular to the axis of rotation of the machine. The plane of the electrical connection can be away from the stator mass by less than 60 mm, better still less than 40 mm, for example 27 mm or 38 mm approximately.

A majority of the electrical conductors housed in a first notch can each be electrically connected to a respective second electrical conductor housed in a second notch, at the exit from said notches. At least one notch, better still a majority of the notches, or even more than half of the notches, better more than two-thirds of the notches, or even all of the notches, may each have first electrical conductors electrically connected to a respective second electrical conductor housed in a second notch, at the outlet of said notches.

In one embodiment, all the electrical conductors having a free end located at the same circumferential position around the axis of rotation of the machine, regardless of their radial position, are electrically connected together.

The first and second electrical conductors can each have an oblique portion. The oblique portions may extend in a circumferential direction, around the axis of rotation of the machine. The two oblique portions can be configured to converge towards each other and thus allow the electrical connection to be made.

An electrical conductor can have two oblique portions, one at each of its two ends. The two oblique portions of the same electrical conductor can extend in opposite directions. They can diverge from each other. They can be symmetrical to each other.

A majority of the electrical conductors can include one or more oblique portions as described above.

The electrical conductors can be arranged in the notches in a distributed manner. By “distributed”, it should be understood that the outgoing and return electrical conductors are each housed in different and non-consecutive notches. At least one of the electrical conductors can pass successively through two non-consecutive notches. The electrical conductors can be arranged in a row in the notches. By “row” is meant that the electrical conductors are not arranged in the slots in bulk but in an orderly manner. They are stacked in the notches in a non-random manner, being for example arranged in a row of electrical conductors aligned in the radial direction. Alternatively, they are arranged in a row of electrical conductors aligned in the circumferential direction around the axis of rotation of the machine. In one embodiment, the strands of one or more electrical conductors are arranged in a row of electrical conductor strands aligned in the radial direction. Alternatively, they are arranged in a row of strands of electrical conductors aligned in the circumferential direction around the axis of rotation of the machine.

The electrical conductors may have a generally rectangular cross section, in particular with rounded edges. The circumferential dimension of an electrical conductor can correspond substantially to the width of a notch. Thus, a notch may have in its width only one electrical conductor. The width of the notch is measured in its circumferential dimension around the axis of rotation of the machine.

Electrical conductors can be adjacent to each other by their long sides, otherwise called the flat.

Optimization of the stack can allow a greater quantity of electrical conductors to be placed in the slots and thus obtain a stator of greater power, at constant volume.

Each notch can include two to 36 electrical conductors, in particular two to 24, better still 2 to 12 electrical conductors. Each notch may include two to eight electrical conductors, in particular two to four electrical conductors, for example two or four electrical conductors. In an alternative embodiment, each notch has two electrical conductors. In another variant embodiment, each notch has four electrical conductors.

Pins

Electrical conductors at least, see a majority of electrical conductors, can be in the shape of pins, U or I. The pin can be U-shaped ("U-pin" in English) or straight, being in form of I ("I-pin" in English).

The hairpin and flat electrical conductors increase the fill factor of the slot, making the machine more compact. Thanks to a high filling coefficient, the thermal exchanges between the electrical conductors and the stator mass are improved, which makes it possible to reduce the temperature of the electrical conductors inside the slots.

In addition, the manufacture of the stator can be facilitated by the electrical conductors in the form of pins. In addition, the winding with pins can be easily changed by changing only the connections between the pins at the coil heads. Finally, since the pins do not need to have open notches, we can have closed notches that allow the pins to be held and we can therefore eliminate the step of inserting the stator shims.

Electrical conductors, or even a majority of electrical conductors, extend axially into the notches. The electrical conductors can be introduced into the corresponding notches through one or both axial ends of the machine.

An I-shaped electrical conductor has two axial ends each placed at one of the axial ends of the stator. It passes through a single notch, and can be welded at each of its axial ends to two other electrical conductors, at the level of the axial ends of the stator. The stator may for example comprise 6, 10, 12, 14, 18, 22 or 26 electrical conductors in the shape of an I, the other electrical conductors possibly all being in the shape of a U.

A U-shaped electrical conductor has two axial ends both placed at one of the axial ends of the stator. It passes through two different slots, and can be welded at each of its axial ends to two other electrical conductors, at the same axial side of the stator. The bottom of the U is on the other axial side of the stator.

Strands

In the invention, each electrical conductor has one or more strands ("wire" or "strand" in English). By "strand" we mean the most basic unit for electrical conduction. A strand can be of round cross section, one can then speak of "wire", or flat, being for example of substantially rectangular cross section. The flat strands can be shaped into pins, for example U or I or belt. Each strand is coated with insulating enamel.

The fact that each notch can include several electrical conductors and / or several strands makes it possible to minimize losses by induced currents, or Joule AC losses, which evolve with the square of the supply frequency, which is particularly advantageous at high frequency and when the operating speed is high. It is thus possible to obtain better efficiency at high speed.

The presence of the closed notches can make it possible to obtain a reduction in the flow of leaks seen by the electrical conductors, which results in a decrease in eddy current losses in the strands.

In one embodiment, each electrical conductor may include several pins, each forming a strand, as explained above. All strands of the same electrical conductor can be electrically connected to each other at the exit of the notch. The strands electrically connected to each other are placed in short circuit. The number of strands electrically connected together may be greater than or equal to 2, being for example between 2 and 12, being for example 3, 4, 6 or 8 strands.

Several strands can form the same electrical conductor. The same electric current of the same phase circulates in all the strands of the same electrical conductor. All the strands of the same electrical conductor can be electrically connected to each other, in particular at the outlet of the notch. All the strands of the same electrical conductor can be electrically connected to each other at each of their two ends axial, in particular at the exit of the notch. They can be electrically connected in parallel.

All strands of all electrical conductors having a free end located at the same circumferential position around the axis of rotation of the machine, regardless of their radial position, can be electrically connected to each other.

In another embodiment, each electrical conductor has three strands.

In the case where a notch has two electrical conductors, a notch can therefore accommodate six strands, for example, distributed between the two electrical conductors.

As a variant, a notch has four electrical conductors. Each electrical conductor can have two strands. The notch then accommodates eight strands, distributed between the four electrical conductors.

The strands can be positioned in the notch so that their circumferential dimension around the axis of rotation of the machine is greater than their radial dimension. Such a configuration allows a reduction in Loucault current losses in the strands.

A strand may have a width of between 1 and 5 mm, for example being of the order of 2.5 or 3 mm. The width of a strand is defined as the largest dimension of the cross section of the strand, which corresponds to its dimension in the circumferential direction around the axis of rotation of the machine.

A strand may have a thickness of between 1 and 4 mm, being for example of the order of 1.6 or 1.8 mm. The thickness of a strand is defined as the smallest dimension of the cross section of the strand, which corresponds to its dimension in the radial dimension.

A ratio of the width of a strand to its thickness can be between 1 and 2.5, better still between 1.2 and 2, or even between 1.4 and 1.8, being for example 1.56 or 1 , 66. Such a ratio allows a reduction in losses by Loucault currents in the strands.

The electrical conductors can be made of copper or aluminum.

Insulators

The electrical conductors are electrically isolated from the outside by an insulating coating, including enamel. The electrical conductors can be separated from the walls of the notch by an insulation, in particular by at least one sheet of insulation. Such a sheet insulation allows better insulation of the electrical conductors with respect to the stator mass. The use of closed notches can improve the retention of insulation around electrical conductors in the notches.

Notches The notches can be open or at least partially closed. A partially closed notch makes it possible to provide an opening at the level of the air gap, which can be used, for example, for the installation of the electrical conductors for filling the notch. A partially closed notch is in particular formed between two teeth which each have pole shoes at their free end, which close the notch at least in part.

Alternatively, the notches can be completely closed. By "fully closed notch" is meant notches which are not open radially towards the air gap.

The presence of closed notches makes it possible to improve the performance of the electric machine in terms of the quality of the magnetic field in the air gap, by minimizing the harmonic content and the losses by eddy currents in the electrical conductors, and the leakage fluxes in the air gap. the notches, as well as the fluctuations of the magnetic field in the air gap and heating of the machine. In addition, the presence of these closed notches improves the mechanical rigidity of the stator, mechanically strengthening the stator and reducing vibrations.

The stator mass can be produced by stacking magnetic sheets, the notches being formed by cutting the sheets. The stator mass can also be produced by cutting from a mass of sintered or agglomerated magnetic powder.

Stator

A further subject of the invention, independently or in combination with the above, is a stator of a rotating electrical machine, comprising a stator mass comprising notches in which are arranged electrical conductors, at least one of which is an electrical conductor as described above. .

At least one strand of the electrical conductor or conductors may be flat. A flattened strand may have a substantially rectangular cross section.

In one embodiment, a majority of the electrical conductors include at least one strand covered at least partially, or even completely, by a layer of an adherent material, in particular heat-adherent.

As a variant, all of the electrical conductors comprise at least one strand covered at least partially, or even completely, by a layer of an adherent material, in particular thermo-adherent

At least part of the electrical conductors, or even a majority of the electrical conductors, being in the form of a U-shaped pin, each comprising first and second legs, can extend axially respectively in first and second notches. Advantageously, the electrical conductors of the stator can be devoid of a layer of material adhering to the surface which faces another electrical conductor.

Alternatively, the electrical conductors can be covered with a layer of material adhering to the surface that faces another electrical conductor.

Machine and rotor

Another subject of the invention is a rotating electrical machine, such as a synchronous motor or a synchronous generator, comprising a stator as defined above. The machine can be synchronous or asynchronous. The machine can be reluctance. It can constitute a synchronous motor.

The maximum speed of rotation of the machine can be high, being for example greater than 10,000 rpm, better still greater than 12,000 rpm, being for example of the order of 14,000 rpm at 15,000 rpm. min, or even 20,000 rpm or 25,000 rpm. The maximum speed of rotation of the machine may be less than 100,000 rev / min, or even 60,000 rev / min, or even less than 40,000 rev / min, better still less than 30,000 rev / min.

The rotating electric machine may include a rotor. The rotor can be permanent magnet, with surface magnets or buried. The rotor can be in flux concentration. It may include one or more layers of magnets arranged in an I, U or V arrangement. Alternatively, it may be a wound rotor or squirrel cage rotor, or a variable reluctance rotor.

The diameter of the rotor may be less than 400 mm, better still less than 300 mm, and greater than 50 mm, better still greater than 70 mm, being for example between 100 and 200 mm.

The rotor may have a rotor mass extending along the axis of rotation and disposed around a shaft. The shaft may include torque transmission means for rotating the rotor mass.

The rotor may or may not be cantilevered.

The machine can be inserted alone in a housing or inserted in a gearbox housing. In this case, it is inserted in a housing which also houses a gearbox.

Manufacturing process of an electrical conductor

The subject of the invention is also a method of manufacturing an electrical conductor as described above and intended to be inserted into the slots of a stator of a rotating electrical machine, the electrical conductor comprising several strands, at least one of the strands. strands being covered at least partially, or even completely, by a layer of an adherent material, in particular heat-adherent, the process comprising the following steps:

(a) assemble the strands of the electrical conductor according to a predefined arrangement, (b) polymerize the layer of adherent material.

At least one strand of the electrical conductor can be flat.

In step (a) of assembly, the strands of an electrical conductor can be arranged parallel to each other in their direction of elongation and they can be given a general predefined shape, for example a U-shape or a U-shape. I.

It is possible to polymerize the entire surface covered with a layer of adherent material. As a variant, it is possible to polymerize only part of the layer of adherent material, for example only the part of the layer located on the straight portions of an electrical conductor, in particular the legs. In particular, one can polymerize the layer of adherent material of the portions intended to be inserted into the notches only. In one embodiment, step (b) of polymerization can be carried out by applying a solvent to the strand or strands covered with a layer of adherent material.

The solvent used to polymerize the adherent material is for example chosen from denatured alcohols, in particular ethanol or methanol. The solvent can be applied by means of a brush or a wick on the strand (s) covered with a layer of adherent material. Alternatively, the solvent can be sprayed onto the strand (s) covered with a layer of adherent material. The solvent can be diluted, especially with water.

In one embodiment, step (b) of polymerization can be carried out by heating the strand or strands covered with a layer of adherent material, in particular thermo-adherent.

The heating temperature of the electrical conductor during step (b) is between 90 ° C and 290 ° C, and better still between 110 ° C and 260 ° C, being for example between 130 ° C and 230 ° C. To carry out step (b) of polymerization by heating, an electric current can be circulated through the electrical conductor and thus heated by the Joule effect. The intensity of the current depends on the size of the strand and the stator winding produced.

Alternatively, the heat-adherent material can be heated by placing the electrical conductor in a thermal chamber. The temperature in this chamber is for example between 90 ° C and 260 ° C, better still between 110 ° C and 240 ° C, being for example between 130 ° C and 220 ° C. The heating time is for example between 30 seconds and 60 min, better still between 2 min and 45 min, for example between 5 and 30 min. This heating time may depend on the size of the electrical conductor.

As a variant, the heating can be carried out by means of a jet of hot air directed towards the electrical conductor. The temperature of the hot air jet is for example between 100 ° C and 290 ° C, better still between 120 ° C and 260 ° C, for example between 140 ° C and 230 ° C. The temperature to be applied to carry out the polymerization depends on the cross-sectional area of the strand, the winding speed of the stator, and the size and shape of the winding.

Other temperature raising methods can be applied, such as induction heating.

When the strands have a substantially rectangular cross section, the adherent material liquefies during step (b) of polymerization by heating and migrates to the tops of the cross sections of the strands. The strands located at the ends of the electrical conductors may not exhibit an accumulation of adherent material at at least one of the vertices of their cross section.

Advantageously, the method according to the invention may also include the following step: (c) exerting pressure on the strands of the electrical conductor.

This pressure step (c) accentuates the migration of the adherent material towards the tops of the cross sections of the strands.

The pressure can be exerted with a force orthogonal to the direction of elongation of the strands. The pressure can be exerted with a force orthogonal to the contact face between two adjacent strands.

Strand pressure step (c) can be totally or partially simultaneous with polymerization step (b). As a variant, steps (b) of polymerization and (c) of pressure are consecutive. For example, step (b) of polymerization takes place before step (c) of pressure. Alternatively, polymerization step (b) takes place after pressing step (c).

The pressure is for example exerted by means of a tool which encloses the strands of an electrical conductor between the jaws. This exerted pressure makes it possible to glue the strands together. When the strands are squeezed, excess adhering material is flushed out to the sides. There may only be a thin layer between the strands. The extra thickness created by the layer of adherent material can thus be reduced.

The tool used to press the strands of an electrical conductor can also be provided with heating means. For example, the jaws can include heating resistors. In the event that the electrical conductor has one or more strands covered with a layer of thermo-adhesive material, these heating jaws allow the material to polymerize.

The electrical conductor obtained by this process has improved rigidity. In addition, the risk of strand expansion is reduced. Advantageously, assembly step (a) can be preceded by the following step:

(d) depositing a layer of adherent material, in particular heat-adherent, on at least one of the strands of the electrical conductor.

The layer of adherent material can be deposited over the entire periphery of the strand in cross section. As a variant, the layer of adherent material can be deposited in the form of dots and / or a strip on the strand. As a variant, the layer of adherent material can be deposited on one or more faces of the strand. Alternatively, the deposition of the layer of adherent material can be done on one side of a strand in contact with an adjacent strand.

The assembly step (a) is preferably followed by the following step:

(e) shaping of the electrical conductor.

The shaping step (e) can take place before or after the polymerization step (b). The step (e) of shaping the electrical conductor gives it a pin shape, preferably a U or I pin or belt shape.

To form a U-shaped pin, the strands of an electrical conductor are held around a holding finger, then the two legs of the electrical conductor are pushed apart in a direction orthogonal to the direction of elongation of the strands.

The shaping step (e) can be done by means of a device comprising two movable elements between them, namely a first movable element and a second movable element. One of the elements is, for example, cylindrical in shape. The first leg of a conductor is inserted into the first movable member and the second leg is inserted into the second movable member. The moving parts are then set in motion relative to each other to move the first and second legs in two opposite directions to move them apart.

Method of manufacturing a stator

A further subject of the invention is a process for manufacturing a stator, comprising the following step:

(f) insertion of an electrical conductor manufactured by the method described above in the notches of the stator.

The use of electrical conductors according to the invention facilitates the manufacture of the stator. Electrical conductors are more rigid than those without a strand covered with a layer of adherent material. Their insertion into the notches of the stator is consequently facilitated.

In addition, the risk of the electrical conductors buckling during their insertion into the notches is reduced. Polymerization step (b) which enables the layer of adherent material to be activated can take place after insertion step (e) in the notches of the stator. The activation of the adherent material can therefore be carried out after the stator has been wound.

The method can also include a step of impregnating the stator. This impregnation step improves the filling of the notches. Indeed, the impregnation varnish fills the free spaces in the notches.

Brief description of the drawings

The invention can be better understood from reading the detailed description which follows, of an exemplary non-limiting embodiment thereof, and from examining the appended drawing, in which:

Figure 1 is a perspective view, schematic and partial, of a stator produced in accordance with the invention,

FIG. 2 is a perspective view, schematic and partial, of the stator of FIG. 1, FIG. 3 is a detail view, in perspective, of the stator of FIG. 1,

Figure 4 shows in cross section, schematically and partially, the stator mass of the stator according to the invention,

Figure 5a is a schematic representation of an electrical conductor strand according to the invention seen in cross section,

Figure 5b is a view similar to Figure 5a of an alternative embodiment,

Figure 5c is a view similar to Figure 5a of an alternative embodiment,

Figure 6a is a schematic representation of an electrical conductor according to the invention seen in cross section,

FIG. 6b is a view similar to FIG. 6a of an alternative embodiment, FIG. 6c is a view similar to FIG. 6a of an alternative embodiment, FIG. 6d is a view similar to FIG. 6a of an alternative embodiment, FIG. 7 is a schematic view of the tool for bending the strands of an electrical conductor according to the invention,

Figure 8 is a schematic view of the step of shaping the pinhead, Figure 9a is a front view of an embodiment of the step of separating the legs of an electrical conductor ,

Figure 9b is a view similar to Figure 9a of the end of the step of separating the legs of an electrical conductor according to the invention,

FIG. 9c is a side view of FIG. 9a. FIG. 10 is a schematic view of an embodiment of the step of polymerization of the adherent material,

FIG. 11 is a schematic view of an electrical conductor after the step of polymerization of the adherent material.

detailed description

There is illustrated in Figures 1 to 4 a stator 2 of a rotating electrical machine 1 also comprising a rotor not shown. The stator is used to generate a rotating magnetic field to drive the rotating rotor, as part of a synchronous motor, and in the case of an alternator, the rotation of the rotor induces an electromotive force in the electrical conductors of the stator.

The examples illustrated below are schematic and the relative dimensions of the various constituent elements have not necessarily been observed.

The stator 2 comprises electrical conductors 22, which are arranged in notches 21 formed between teeth 23 of a stator mass 25. The notches 21 are closed.

The electrical conductors 22 have strands 32. The strands 32 have a generally rectangular cross section, in particular with rounded corners. The strands 32 are in the example described superimposed radially in a single row.

The thickness e of a strand 32 is the smallest dimension of the cross section of the strand. As shown in Figure 3, the thickness e of a strand corresponds to its dimension in the radial direction of the machine. The width 1 of a strand 32 is the largest dimension of the cross section of the strand. The width 1 of a strand corresponds to its dimension in the circumferential direction around the axis of rotation of the machine.

The electrical conductors 22 are mostly pin-shaped, i.e. U or I, and extend axially into the notches. A first electrical conductor housed in a first notch is electrically connected to a second electrical conductor housed in a second notch, at the outlet from said notches.

The first and second notches are non-consecutive. In the example shown, they are separated by 7 other notches. Alternatively, the first and second notches are separated by 3, 4, 5, 6, 8, 9, 10 or 11 other notches, for example.

The electrical connection is formed on the electrical conductors just after their exit from the two notches, at one axial end of the stator mass. The two electrical conductors each have an oblique portion 22b, which converge towards one another. The electrical connection between two conductors is made in a plane perpendicular to the axis of rotation of the machine, causing the free ends 22a of the strands of the two electrical conductors to merge.

As illustrated in Figure 4, electrical conductors are arranged in the notches 21 of the stator. These electrical conductors each have three strands 32a, 32b, 32b '. Some strands are covered with a layer of grippy material and others are not. The strands covered with a layer of adherent material are represented by a hatch. The central strand 32a of these conductors is covered at least partially or even completely with a layer of adherent material. The strand closest to 32b ’and the one farthest 32b from the axis of rotation of the electrical machine of each electrical conductor are devoid of such a layer.

Figures 5a, 5b and 5c show a strand 32 of an electrical conductor. Strand 32 includes a layer of insulating material 320.

In the embodiment shown in Figure 5a, a layer of adherent material 321 is deposited on the layer of insulating material 320. The layer of adherent material 321 is deposited on the entire outer surface of the strand 32, when the latter is observed in cross section.

In the embodiment shown in FIG. 5b, the layer of adherent material 321 is deposited on the layer of insulating material 320. The layer of adherent material 321 is deposited in the form of bands on one side of the strand. As a variant, the strips of layer of insulating material can be deposited on several faces of the strand.

In the embodiment shown in Figure 5c, the layer of adherent material 321 is deposited on the layer of insulating material 320. The layer of adherent material 321 is deposited on all of one side of the strand.

In the embodiment shown in Figure 6a, the layer of adherent material 321 is located at the interface between two strands 32 and 32 ’.

Each strand 32 has a proximal face 41 and a distal face 42. The proximal face 41 is the face of a strand closest to the axis of rotation of the machine. Distal face 42 is the face of a strand furthest from the axis of rotation of the machine.

Illustrated in Figure 6b, an electrical conductor 22 which has three strands 32, 32 ', 32 ”. In the embodiment shown, the proximal faces 41 of the strands 32 and 32 'are covered with a layer of adherent material and the distal faces 42 of the strands 32 and 32' as well as the proximal 41 and distal 42 faces of the strand 32 ” do not have it. In an alternative embodiment not shown, the adherent material can be deposited in the form of tape or point. In another variant embodiment, not shown, the distal faces 42 of the strands 32 and 32 'are covered with a layer of adherent material and the proximal faces 41 of the strands 32' and 32 ”as well as the proximal 41 and distal 42 faces of the strand. 32 do not.

FIG. 6c shows an alternative embodiment in which the proximal face 41 and the distal face 42 of the strand 32 ′ are provided with a layer of adherent material 321 and the strands 32 and 32 ″ are devoid of it.

Illustrated in Figure 6d is an alternative embodiment in which the layer of adherent material 321 is deposited over the entire outer surface of the strand 32 ’. Strands 32 and 32 "are devoid of such a layer. In this embodiment, when the electrical conductor 22 is viewed in cross section, the layer of material 321 covers the faces 322 of the strand 32 'which are not in contact with another adjacent strand 32, 32 ". The strand on which the adherent material has been previously applied is therefore distinguished from those to which the adherent material has not been previously applied.

Figure 7 illustrates the step of bending the strands 32, 32 ’, 32” of an electrical conductor according to the invention. This step makes it possible to assemble the strands 32, 32 ', 32 ”and give them a general U-shape. The three strands 32, 32', 32” of the electrical conductor are arranged around an adjustable stop 43. A clamp has two jaws 44, 44 '. The jaw 44 is fixed. As a variant, it can be mobile. Jaw 44 ’can be fixed or movable. This clamp keeps the strands 32, 32 ", 32" parallel to each other during the bending operation. The bending device also has a 44 ”movable jaw. The latter makes it possible to shape the electrical conductor. The jaws 44, 44 "and 44" may include heating resistors 50. These can allow the layer of adherent material which covers the strand (s) 32 to be polymerized by heating it. Following the bending step, a pinhead shaping operation is performed. This step makes it possible in particular to give the head of the pin a P shape. This operation is illustrated in figure 8. In order to shape the head of the pin, the strands 32, 32 ', 32 ”are clamped between two movable jaws 45 and 45 'and around a fixed part 46. The jaw 45 is able to move along the arrow F. These jaws 45, 45' make it possible to apply on the strands 32, 32 ', 32 ”a pressure force orthogonal to the direction of elongation of the strands.

The jaws 45, 45 'and the fixed part 46 can include heating resistors 50. These can make it possible to polymerize the layer of adherent material which covers the strand or strands 32 by heating it. In an alternative embodiment, the heating is carried out simultaneously with the pressure exerted by the jaws 45, 45 ', by applying an electric current to the strands 32, 32', 32 ”of the electrical conductor. The heating in the strands due to the passage of electric current makes it possible to polymerize the layer of thermo-adhesive material present on at least one of the strands 32, 32 ', 32 ”. In addition, the pressure exerted on the strands 32, 32 ', 32 ”makes it possible to evacuate the excess of heat-adherent material on the sides. Thus, only a thin layer of thermo-adherent material remains between the strands 32, 32 ', 32 ”.

The step of shaping the pinhead is followed by a step of separating the legs of the electrical conductor illustrated in Figures 9a, 9b, 9c and 10.

Figures 9a and 9c illustrate the initial arrangement of the elements necessary for the implementation of the strand spacing method. A first leg 22e of an electrical conductor is inserted into a movable member 48 which is able to move around a wheel 47. The second leg 22f of the electrical conductor is inserted into the wheel 47. The spacing of the legs 22e and 22f of the electrical conductor is effected by moving the movable element 48 until the latter comes into contact with a stop 49, as shown in FIG. 9b.

FIG. 10 illustrates an embodiment where the step of spreading the legs of the electrical conductor and the polymerization of the adherent material are carried out simultaneously. Each leg 22e and 22f is clamped in a heating clamp comprising a fixed jaw 51 and a movable jaw 52. As a variant, the jaw 51 is movable and the jaw 52 is fixed. These jaws include heating resistors 50 which allow the layer of adherent material present on at least one strand 32, 32 ", 32" to be polymerized.

The heated clamps move the first and second legs in two opposite directions to move them apart.

In this embodiment, it is possible to selectively polymerize certain areas of the layer of adherent material. In particular, it is possible to polymerize only the legs 22e 22f of the electrical conductor which will be inserted into the notches of the stator.

Heating can take place at one or more of the stages shown in Figures 7, 8 or 10. In particular, heating takes place during one stage only.

FIG. 11 is an example of an electrical conductor according to the invention after the step of polymerization of the adherent material. During the polymerization step, the adherent material liquefies and migrates to the tops of the cross sections of the strands. Thus, the adherent material accumulates in areas 323 around the tops of the cross sections of the strands. In the embodiment shown in Figure 11, only the middle strand 32 'has been covered with a layer of adherent material. Therefore, the 324 zones around the tops located at the ends of the electrical conductor 22 are not covered with adherent material.

Of course, the invention is not limited to the exemplary embodiments which have just been described, and the rotor associated with the stator described may be wound, with a squirrel cage or with permanent magnets, or else with variable reluctance. In addition, other distributions of the strands covered by a layer of thermo-adherent material and those not covered than those illustrated can be used to achieve the invention.

The expression "comprising a" should be understood as being synonymous with "comprising at least one".

Claims

[Claims]

1. Electrical conductor, in particular in the form of a U-shaped or I-shaped pin, intended to be inserted into the notches (21) of a stator (2) of a rotating electrical machine (1), the electrical conductor (22) comprising several strands (32), at least one strand being flat, at least one of the strands being covered at least partially, or even completely, by a layer of an adherent material, in particular thermo-adherent (321),

the strand or strands covered at least partially (32a), or even completely, with a layer of adherent material (321) being arranged between two strands (32b, 32b ’) without such a layer.

2. Electrical conductor, in particular in the shape of a U-shaped or I-shaped pin, intended to be inserted into the notches (21) of a stator (2) of a rotating electrical machine (1), the electrical conductor (22) comprising several strands (32), at least one strand being flat, at least one of the strands being covered at least partially, or even completely, by a layer of an adherent material, in particular thermo-adherent (321),

the layer of adherent material being applied over the layer of insulating material.

3. Electrical conductor according to one of the two preceding claims, all the strands (32) of an electrical conductor (22) being covered at least partially, or even completely, with a layer of adherent material (321).

4. Electrical conductor according to one of the three preceding claims, one in two strands being covered at least partially, or even completely, with a layer of adherent material (321).

5. Electrical conductor according to any one of the preceding claims, one of the strands (32) comprising a contact face (42,41) with an adjacent strand (32 '), this face being covered at least partially with a layer of adherent material (321).

6. Electrical conductor according to any one of the preceding claims, the layer of adherent material (321) having a thickness c between 0.05 mm and 0.2 mm, better still between 0.07 mm and 0.15 mm, being for example 0.1 mm.

7. Stator of a rotating electrical machine, comprising a stator mass (25) comprising notches (21) in which conductors are arranged. electrical (22), at least one of which is an electrical conductor according to one of the preceding claims.

8. Stator according to the preceding claim, the electrical conductors being devoid of a layer of adherent material (321) on the surface which faces another electrical conductor.

9. Rotating electric machine comprising a stator (2) according to one of the two preceding claims and a rotor.

10. A method of manufacturing an electrical conductor, in particular according to any one of claims 1 to 6, intended to be inserted into the notches (21) of a stator (2) of a rotating electrical machine (1), the conductor. electrical (22) comprising several strands (32), at least one of the strands being covered at least partially, or even completely, by a layer of an adherent material, in particular heat-adherent (321), the method comprising the following steps:

(a) assemble the strands (32) of the electrical conductor (22) according to a predefined arrangement,

(b) polymerizing the layer of adherent material (321).

11. Method according to the preceding claim, step (b) of polymerization being carried out by applying a solvent to the strand or strands covered with a layer of adherent material (321).

12. The method of claim 10, step (b) of polymerization being carried out by heating the strand or strands covered with a layer of adherent material, in particular heat-adherent (321).

13. Method according to one of the three preceding claims, also comprising the following step:

(c) exerting pressure on the strands (32) of the electrical conductor (22).

14. Method according to one of claims 10 to 13, the assembly step (a) being preceded by the following step:

(d) depositing a layer of adherent material (321) on at least one of the strands (32) of the electrical conductor (22).

15. Method according to one of claims 10 to 14, assembly step (a) being followed by the following step:

(e) shaping of the electrical conductor (22)