WO2021111054A1

WO2021111054A1 - Device for holding electrical conductors to be welded

Info

Publication number: WO2021111054A1
Application number: PCT/FR2020/052093
Authority: WO
Inventors: Romaric Lenoir; Cyril Moya
Original assignee: Nidec Psa Emotors
Priority date: 2019-12-04
Filing date: 2020-11-17
Publication date: 2021-06-10
Also published as: FR3104337A1; EP4070441A1; FR3104337B1

Abstract

Disclosed is a device for holding one or more electrical conductors of a stator of a rotating electrical machine, the device defining one or more internal spaces adapted to receive one or more electrical conductors to be welded, the device being intended to retain, in each interior space, the fused material from a step of welding said electrical conductors.

Description

Title: Device for holding electrical conductors to be welded

The present invention claims the priority of the French application 1913712 filed on December 4, 2019, the content of which (text, drawings and claims) is incorporated here by reference.

The present invention relates to a device for holding one or more electrical conductors to be welded of 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, wind or aeronautical applications.

Prior art

The welding of several adjacent electrical conductors in a so-called raised edge configuration, that is to say with electrical conductors which are at the same height, leads to welds which are difficult to penetrate. In addition, the more the number of strands per electrical conductor increases, the more the welding energy required to solder the electrical conductors increases.

When the energy required for welding is very high, in order to increase the penetration of the weld, there is a risk of destruction of the electrical conductors by accumulation of energy in the end to be welded, then fusion and collapse of it. this.

This high energy input can also lead to pronounced degradation of the insulation and wires and potentially of the stator notch insulators, which can lead to functional failures. The high energy input can also cause a large volume of fused material to form, which can lead to welds having a large width. This large width can prove to be problematic, in particular in the case where the pitch of the notches of the stator is reduced. Indeed, the stator welds then being close together and wide, there is a risk of short circuit.

There is a need for simply soldering electrical conductors together, without risking damaging them during the welding operation, and reducing the risks of short circuits in the stator.

Disclosure of the invention

The invention aims to allow easy welding of the electrical conductors of a rotating electrical machine stator, while controlling the geometry of the weld by means of a holding device.

Summary of the invention

Holding device

The object of the invention is thus, according to one of its aspects, a device for holding one or more electrical conductors of a rotating electrical machine stator, the device delimiting one or more interior spaces suitable for receiving one or more. electrical conductors to be welded, the device being intended to retain in each interior space the fused material resulting from a step of welding said electrical conductors.

Each interior space defines a crucible in which the welding of the electrical conductor (s) can be carried out. The holding device makes it possible to limit the flow of fused material resulting from the weld. One can thus simply control the volume expansion of the weld, in particular its expansion towards the sides.

The interior spaces, when viewed in cross section, are preferably closed spaces which prevent the fused material from flowing out of the device.

In addition, the retainer according to the invention allows the fused material to be contained within an interior space during the solidification phase. This allows a predetermined shape to be imposed on the weld.

Controlling the geometry of the weld reduces the risk of a short circuit in the stator. Indeed, when the pitch of the notches is reduced, too large a weld width can cause contact between electrical conductors arranged in different notches, thus resulting in a short circuit. In addition, mastering the geometry of the weld makes it possible to limit the peak effect in the electrical conductor (s). The term “peak effect” is understood to mean an accumulation of heat in the end (s) of the electrical conductor (s). In fact, the holding device makes it possible to promote the evacuation of the heat resulting from the welding.

At least electrical conductors, if not a majority of electrical conductors, can be in the shape of pins, U or I.

When observed in cross section, the interior space (s) have an area substantially equal to that of a cross section of the electrical conductor (s) to be welded.

The holding device may have the general shape of a cylinder. It may have an upper face and a lower face. The lower face is for example intended to come opposite the stator during the welding step.

The axis of revolution of the holding device can be confused with the axis of rotation of the rotating electrical machine.

Preferably, the retaining device may have an outline having a shape similar to that of a cross section of the stator. For example, the device has a cylindrical shape with a circular cross section. The use of a holding device having a cylinder shape of substantially circular cross section facilitates its insertion on the stator of a rotating electrical machine.

Each interior space may be delimited by two radial edges extending in radial directions of the rotating electrical machine and two circumferential edges extending in circumferential directions around the axis of rotation of the rotating electrical machine.

In one embodiment, the radial edges and the circumferential edges have different heights.

For example, if the radial edges are higher than the circumferential edges, then the upper face of the holding device corresponds to the space defined by the upper faces of the radial edges.

If the radial edges are lower than the circumferential edges, the upper face of the holder then corresponds to the space defined by the upper faces of the circumferential edges.

Alternatively, the radial edges and the circumferential edges can have the same height. In this case, the upper face of the holding device then corresponds to the space defined by the set of upper faces of the radial edges and the upper faces of the radial edges.

The holding device may be in physical and / or thermal contact with the electrical conductor (s), in particular in physical and thermal contact with the electrical conductor (s). Electrical conductors are in "thermal contact" with the retainer if they are close enough that heat exchange can take place with the retainer without necessarily having physical contact.

The upper face of the device before welding may protrude from the free end (s) of the electrical conductor (s) with a height h less than 5 mm, better less than 4 mm, even better less than 3 mm, for example of the order of 2 mm.

The choice of such a lower limit makes it possible to ensure that the free ends of the strands of the electrical conductor or conductors to be welded are sufficiently high in the device to be easily accessible during welding. Indeed, if the device protrudes too far from the free ends of the conductor (s) to be soldered, it is more difficult to approach the heat source to solder the electrical conductors. In addition, if the upper face of the device is too high, it may interfere with the movement of the heat source from one space inside the holder to another.

The upper face of the device before welding may protrude from the free end (s) of the electrical conductor (s) by a height greater than 1 mm, better still greater than 1.5 mm, for example of the order of 2 mm.

Thus, the solder resulting from the soldering of the electrical conductors can remain inside one of the interior spaces delimited by the holding device according to the invention, without going beyond the upper face of the device. The geometry of the weld can then be easily controlled. The choice of such an upper limit for the height h makes it possible to ensure that the contact surface between the holding device and the electrical conductors is large enough to allow the heat associated with the solder to be efficiently removed.

The device can be made from a refractory material, for example a material chosen from the following list, which is not limiting: ceramic, in particular alumina, boron nitride, graphite, tungsten, molybdenum , niobium, platinum, tantalum or rhenium, and their alloys. A refractory material is a material capable of withstanding high temperatures without undergoing significant physical or chemical transformation. The refractory material can be resistant to temperatures greater than 1100 ° C, or even greater than 1500 ° C, better still greater than 2000 ° C, or even greater than 2500 ° C, even better still greater than 3000 ° C.

The interior space (s) may have an elongated shape, when viewed in cross section, for example an oblong or rectangular shape.

In one embodiment, all of the interior spaces are oblong in shape when viewed in cross section. Alternatively, all interior spaces are rectangular in shape when viewed in cross section. Still alternatively, a portion of the interior spaces are oblong when viewed in cross section and the remainder of the interior spaces are rectangular when viewed in cross section.

Advantageously, at least one interior space has a larger dimension extending in a radial direction of the rotating electrical machine.

Alternatively, the interior space (s) may have a larger dimension which extends in a circumferential direction around the axis of rotation of the rotating electrical machine.

Each electrical conductor can have one or more strands. The free ends of the strands of the electrical conductor or conductors to be welded can be placed at the same height in each interior space.

In another embodiment, the free ends of adjacent strands of an electrical conductor can be axially offset by a non-zero distance d in each interior space.

Together

Another subject of the invention is an assembly comprising a holding device according to the invention and a stator of a rotating electrical machine, the stator comprising a stator mass comprising notches formed between teeth, each notch receiving one or more electrical conductors.

In one embodiment, the electrical conductors received in the same notch are the electrical conductors received in the same interior space of the holding device, to be welded together.

The stator can include at least electrical conductors, or even a majority of electrical conductors, in the shape of pins, U or I. In one embodiment, the electrical conductors received in the same notch are the electrical conductors received in the same interior space of the holding device, to be welded together.

Preferably, the interior spaces of the holding device are arranged circumferentially with respect to the axis of rotation of the rotating electrical machine. Thus, the arrangement of the interior spaces in the holding device corresponds to that of the notches in the stator mass.

The number of interior spaces of the retainer can be equal to the number of notches in the stator.

Thus, all the free ends of the electrical conductors of the stator can be inserted into the holding device. It is then possible to weld all of the electrical conductors in the notches of the stator without modifying the positioning of the holding device during the welding operation.

The number of interior spaces of a holding device according to the invention may 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 60 or 63.

Welding process

A further subject of the invention is a method of welding electrical conductors of an electric machine stator, comprising at least the following steps:

(a) place a retaining device according to the invention on the stator, in order to hold the electrical conductors of the stator in place,

(b) cause the electrical conductors to melt in order to weld them together,

(c) remove the stator retainer.

In a preferred embodiment, the time interval between step (b) of melting and step (c) of removing the device is long enough to allow cooling and then solidification of the fused material. Solidification can be total or partial. Preferably, it is total. For example, the time interval between the melting step (b) and the device removal step (c) is between 1 s and 20 s, preferably between 2 s and 15 s, better between 3 s and 10 s, being for example of the order of 5 s.

Melting step (b) can be carried out by means of a heat source, in particular a laser or an electric arc, for example an electric arc produced by means of a tungsten electrode. The welding process using a tungsten electrode can be TIG welding (in English “Tungsten Inert Gas”). In this welding process, the electric arc is produced from a tungsten electrode and a plasma. The use of a heat source makes it possible to merge the free ends of the strands without degrading the assembly of the strands of the electrical conductor (s). A single heat source can be used to produce the same weld. As a variant, several heat sources can be used to produce the same weld, each performing welds in separate notches simultaneously.

In one embodiment, a single heat source is used to perform step (b) of melting. Alternatively, two heat sources can be used. As a further variant, more than two heat sources can be used.

The holding device according to the invention allows the energy from the heat source to be concentrated towards the electrical conductors. It is thus possible to use a heat source of medium precision, for example TIG welding. The method according to the invention is thus more economical because it is not necessary to use a precise heat source such as, for example, a laser.

Stator

The subject of the invention is also a stator for a rotating electric machine, comprising a stator mass comprising notches formed between teeth, each notch receiving one or more electrical conductors, the stator comprising at least one weld between at least two electrical conductors.

The length of said weld may be substantially equal to the total length of the electrical conductors engaged in said weld and / or the width of said weld may be substantially equal to the width of the electrical conductors engaged in said weld, when observed in cross section.

For example, if two electrical conductors are welded together according to their width, the length of the weld will be equal to the sum of the lengths of the two conductors and the width of the weld will be equal to the width of the electrical conductors.

The use of a holding device according to the invention makes it possible to control the geometry of the weld. The geometry of the weld can thus be imposed by the holding device. Without the use of such a device, the solder between two electrical conductors would have a volume and a shape related to the surface tension of the fused material. In one embodiment of the invention, all of the stator welds have a width equal to the width of the electrical conductors engaged in the weld and a length equal to the total length of the electrical conductors engaged in the weld.

As a variant, only part of the stator welds have a width equal to the total width of the electrical conductors engaged in the weld and a length equal to the total length of the electrical conductors engaged in the weld. The other welds can have a free form.

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 focused 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 winding, 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 poles of the stator or to the number of pairs of poles.

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 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 accommodate 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, TIG, induction, friction, ultrasound, vibrations, or soldering, 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 of said notches. At least one notch, better still a majority of the notches, or even more than half of the notches, better still more than two-thirds of the notches, or even all the notches, may include first electrical conductors each electrically connected to a respective second electrical conductor housed in a second notch, at the exit 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. The term “row” is understood to mean that the electrical conductors are not arranged in the notches 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. As a variant, 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 strands of electrical conductors aligned in the radial direction. As a variant, they are arranged in a row of conductor strands electrical 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.

The optimization of the stack can make it possible to place in the notches a greater quantity of electrical conductors and thus to 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 notch, 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 modified 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 which make it possible to hold the pins and it is therefore possible to 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 axial ends of the stator. The stator may for example comprise six or twelve 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 located 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, we can then speak of "wire", or flat. The flat strands can be shaped into pins, for example a U or an I. Each strand is coated with an 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 the strands of the same electrical conductor can be electrically connected to each other at the outlet 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 flows through all the strands of the same electrical conductor. All the strands of the same electrical conductor can be electrically connected to each other, especially at the exit of the notch. All the strands of the same electrical conductor can be electrically connected to each other at each of their two axial ends, in particular at the exit from 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 G 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 the losses by Loucault currents in the strands.

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

A strand may have a height of between 1 and 4 mmm, for example being of the order of 1.6 or 1.8 mm. The height of a strand is defined as its thickness in the radial dimension.

A ratio of the width of a strand to its height 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 the losses by Loucault currents in the strands.

The electrical conductors can be made of copper or aluminum. Insulators

The electrical conductors are electrically insulated 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 insulator 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 placement 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 the 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 eddy current losses in the electric 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.

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 described above. The stator may include a stator mass comprising notches formed between teeth, each notch receiving one or more electrical conductors. 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 or even 20,000 rpm or 25,000 rpm. The maximum speed of rotation of the machine may be less than 100,000 rpm, or even 60,000 rpm, or even less than 40,000 rpm, better still less than 30,000 rpm.

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 can include one or more layers of magnets arranged in I, U or V. Alternatively, it can be a wound rotor or squirrel cage, 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 include 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.

Brief description of the drawings

[Lig 1] Figure 1 is a perspective view, schematic and partial, of a stator manufactured in accordance with the invention,

[Lig 2] FIG. 2 is a perspective, schematic and partial view of the stator of FIG. 1,

[Lig 3] FIG. 3 is a detail view, in perspective, of the stator of FIG. 1, [Lig 4] FIG. 4 is a top view of an example of a device according to the invention, [Fig 5a] Figure 5a is a longitudinal sectional view of the free ends of conductors to be welded arranged in an interior space of an exemplary device according to the invention, before welding,

[Fig 5b] Figure 5b is a longitudinal sectional view of the free ends of conductors to be welded arranged in an interior space of an example of a device according to the invention, during welding,

[Fig 5c] Figure 5c is a longitudinal sectional view of the free ends of conductors to be welded arranged in an interior space of an example of a device according to the invention, after welding,

[Fig 6a] Figure 6a is a perspective view of the free ends of conductors to be welded arranged in several interior spaces of an example of a device according to the invention, before welding,

[Fig 6b] Figure 6b is a perspective view of the free ends of conductors to be welded arranged in several interior spaces of an example of a device according to the invention, during welding,

[Fig 7a] FIG. 7a is a view of an interior space of an example of a device according to the invention before the insertion of the free ends of the electrical conductor or conductors to be welded,

[Fig 7b] FIG. 7b is a view of an interior space of an example of a device according to the invention after the insertion of the free ends of the electrical conductor or conductors to be welded,

[Fig 7c] Figure 7c is a view of an interior space of an exemplary device according to the invention after welding the free ends of the electrical conductor (s).

detailed description

There is illustrated in Figures 1 to 3 a stator 2 of a rotating electrical machine 1 also comprising a rotor not shown. The stator generates a rotating magnetic field that drives 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 include strands 33. The strands 33 have a generally rectangular cross section, in particular with rounded corners. The strands 33 are in the example described superimposed radially in a single row.

The thickness e of a strand 33 is its dimension in the radial direction of the machine. The width 1 of a strand 33 is defined as its dimension in the circumferential direction around G axis of rotation of the machine. The width L of the section to be welded corresponds to the sum of the thicknesses e of each strand.

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 they exit the two notches, at one axial end of the stator mass. The two electrical conductors each have an oblique portion 22b, which converge towards each other.

The electrical connection between two conductors is made in a plane perpendicular to the axis of rotation of the machine by causing a fusion of the free ends 22a of the strands of the two electrical conductors.

We will now describe a holding device 3 according to the invention, with reference to Figures 4 to 6b.

FIG. 4 is a top view of a holding device 3, when the latter is observed along the axis of rotation X of the rotary electrical machine. The holding device 3 has a circular cross section. The stator 2, not shown in FIG. 4, also has a circular cross section. The holding device 3 has a plurality of interior spaces 31. These interior spaces 31 are arranged circumferentially around the axis of rotation X of the electric machine. When the retaining device 3 is inserted on the stator 2, the interior spaces 31 coincide with the notches 21. Thus, the electrical conductors 22 arranged in the same notch 21 of the stator are inserted in the same interior space 31.

In the example shown, the number of interior spaces 31 is equal to the number of notches 21 of the stator. All the free ends of the electrical conductors 22 of the stator are thus inserted into the holding device 3. It is then possible to weld all the electrical conductors 22 in the notches 21 of the stator 2 without modifying the positioning of the holding device 3. during the welding operation.

Figures 6a and 6b illustrate a holding device 3 comprising several interior spaces 31 of rectangular shape. In each interior space 31 are inserted several electrical conductors 22 to be welded.

The electrical conductors 22 are arranged radially with respect to the axis of rotation of the rotating electrical machine in each interior space 31. Each interior space 31 is delimited by two radial edges 35 extending in radial directions of the rotating electrical machine and two circumferential edges 34 extending in circumferential directions around the axis of rotation of the rotating electrical machine.

In the exemplary embodiment shown in Figure 6a, the radial edges 35 and the circumferential edges 34 have different heights.

In the example shown, the radial edges 35 are higher than the circumferential edges 34. The upper face of the holding device 3 therefore corresponds to the space defined by the upper faces 32 of the radial edges 35.

FIG. 5a illustrates electrical conductors 22 to be welded arranged in an interior space 31 of a holding device 3 according to the invention. In the example shown, two electrical conductors 22 each comprising three strands 33 are welded. The electrical conductors 22 are in physical and thermal contact with the holding device 3.

In Figures 5a to 6b, the upper faces 32 of the radial edges 35 of the holding device 3 protrude, before welding, the free end (s) of the electrical conductor (s) 22 by a height h of the order of 2 mm. Thus, during welding, the risk of the fused material 41 overflowing over the circumferential edges 34 is reduced.

FIG. 5b illustrates the operation of welding the electrical conductors 22 arranged in an interior space 31 of a holding device 3 according to the invention. A heat source 4 heats the electrical conductors 22 to cause a fusion of these. The fused material 41 resulting from this fusion accumulates in the interior space, above the free ends of the electrical conductors 22. The fused material 41 is held in the interior space 31 and does not flow to the sides. The heat source 4 is for example a tungsten electrode for performing TIG welding.

Figure 5c illustrates the continuation of the welding operation illustrated in Figure 5b. The fused material 41 is contained in the interior space 31 for a time long enough to allow the fused material 41 to solidify. Preferably, one waits until the fused material 41 has completely solidified before moving the holding device 3 away from the electrical conductors 22.

At the end of the welding operation, the fused material 41 does not protrude from the upper face 32 of the device. Thus, the fused material remains contained in the interior space 31. When it solidifies, the fused material 41 then acquires a shape imposed by the interior space 31. When the holding device 3 is removed, the weld resulting from the welding. solidification of the fused material 41 retains the shape imposed on it by the interior space 31. It is thus possible to simply control the geometry of the welds of the electrical conductors of a rotating electrical machine stator.

FIG. 6b illustrates the welding of the electrical conductors 22 by means of a heat source 4. The heat source 4 successively melts the free ends of the electrical conductors 22 arranged in each interior space 31. Once the heat source 4 has completed the welding of the electrical conductors 22 in an interior space 31, it is moved in order to solder the electrical conductors 22 arranged in an adjacent interior space 31. Several heat sources 4 can also be used, each simultaneously performing a weld in separate interior spaces 31.

FIG. 7a shows an interior space 31 of a holding device 3. The interior space 31 is intended to receive electrical conductors to be soldered.

Figure 7b shows the interior space 31 of Figure 3 in which have been inserted electrical conductors 22. The free ends of these electrical conductors 22 are intended to be heated to solder the electrical conductors together.

FIG. 7c represents the interior space of FIGS. 6a and 6b in which electrical conductors 22 have been inserted and then welded. The weld 42 resulting from the solidification of the material fused during welding has a length substantially equal to the total length of the conductors. electrical 22 engaged in said weld and a width substantially equal to the width of the electrical conductors 22 engaged in said weld.

Claims

1. Device for holding (3) one or more electrical conductors (22) of a stator (2) of a rotating electrical machine (1), the device delimiting one or more interior spaces (31), delimited by two radial edges extending in radial directions of the rotating electrical machine and two circumferential edges extending in circumferential directions around the axis of rotation of the rotating electrical machine, adapted to receive one or more electrical conductors (22) to be welded, the device being intended to retain in each interior space (31) the fused material (41) resulting from a step of welding said electrical conductors (22).

2. Device according to the preceding claim, being in physical and thermal contact with the electrical conductor or conductors (22).

3. Device according to one of the two preceding claims, the device having the general shape of a cylinder, comprising an upper face (32) and a lower face, the lower face being intended to come opposite the stator (2) during the welding step.

4. Device according to claim 3, the upper face (32) of the device before welding exceeds the free end (s) of the electrical conductor (s) (22) by a height h less than 5 mm, better still less than 4 mm, or even less than 3 mm.

5. Device according to one of claims 3 or 4, the upper face (32) of the device before welding exceeds the free end or ends of the electrical conductor (s) (22) by a height greater than 1 mm, better greater than 1.5 mm, for example of the order of 2 mm.

6. Device according to any one of the preceding claims, the device being made of a refractory material, in particular ceramic, in particular alumina, boron nitride, graphite, tungsten, molybdenum, niobium, platinum, tantalum or rhenium, and their alloys.

7. Device according to the preceding claim, the refractory material being resistant to temperatures above 1100 ° C, better above 2000 ° C, even better above 3000 ° C.

8. Device according to any one of the preceding claims, the interior space or spaces (31) having an elongated shape, when observed in cross section, in particular an oblong or rectangular shape.

9. Device according to the preceding claim, at least one interior space (31) having a larger dimension extending in a radial direction of the rotating electrical machine (1).

10. Device according to any one of the preceding claims, each electrical conductor (22) comprising one or more strands, the free ends of the strands of the electrical conductor or conductors (22) to be welded being placed at the same height in each interior space ( 31).

11. An assembly comprising a holding device (3) according to any one of the preceding claims and a stator (2) of a rotating electrical machine (1), the stator (3) comprising a stator mass comprising notches (21) formed between teeth (23), each notch receiving one or more electrical conductors (22).

12. Assembly according to the preceding claim, the number of interior space (31) of the holding device (3) being equal to the number of notches (21) of the stator (2).

13. A method of welding electrical conductors (22) of a stator (2) of an electrical machine (1), comprising at least the following steps:

(a) place on the stator (2) a holding device (3) according to any one of claims 1 to 10, in order to hold in place the electrical conductors (22) of the stator (2),

(b) cause the electrical conductors (22) to melt in order to weld them together,

(c) remove the retainer (3) from the stator (2).

14. Method according to the preceding claim, step (b) of melting being implemented by means of a heat source (4), in particular a laser or an electric arc, for example an electric arc produced by means of a tungsten electrode.

15. Stator (2) of a rotating electrical machine (1), comprising a stator mass comprising notches (21) formed between teeth (23), each notch (21) receiving one or more electrical conductors (22), the stator ( 2) comprising at least one weld (42) between at least two electrical conductors (22), the length of said weld (42) being substantially equal to the total length of the electrical conductors (22) engaged in said weld (42) and / or the width of said weld (42) being substantially equal to the width of the electrical conductors (22) engaged in said weld (42), when viewed in cross section.