Device and method for attaching a winding wire to a rotary collector, associated rotary collector, and wound rotor motor

Abstract

The invention relates to an attachment device (250) for attaching a winding wire to a rotary collector (210) that is suitable for providing an electrical connection between a rotor and a power source, wherein the attachment device has an edge (255) defining a slot (254A) through which the winding wire can be inserted. According to the invention, the device comprises at least one sharp projection (258), which is at least partially made of an electrically conductive material and which extends from the edge into the slot.

Description

Description Title of the invention: Device and method for attaching a winding wire to a rotating commutator, associated rotating commutator and wound rotor motor Technical field of the invention

[0001] The present invention relates generally to the electrical connection of a wound rotor of a motor using a rotating commutator.

[0002] It relates more particularly to a device for attaching a winding wire to a rotating collector.

[0003] The invention finds a particularly advantageous application in the electrical connection between a winding wire of a wound rotor, this winding wire being traversed by an electric current, and a rotating collector secured to the rotor, which collector is electrically supplied by a current source fixed relative to the rotor.

[0004] It also relates to a method of attaching the winding wire to such a device, a rotary commutator including such a winding wire attachment device, as well as a wound rotor electric motor comprising this rotary commutator. State of the art

[0005] Hybrid or electric motor vehicles include at least one electric motor powered by a current source and enabling the vehicle to be propelled.

[0006] These electric motors have a part that remains fixed relative to the vehicle chassis, the stator, and a rotating part, the rotor.

[0007] More specifically, some electric motors use a rotor with coils, called a wound rotor. These coils are formed by winding an electrically conductive wire, called a winding wire. The flow of an electric current within the winding wire leads to the generation of a magnetic field. The interaction of the latter with a magnetic field created at the stator generates a torque, thus causing the wound rotor to rotate.

[0008] In order to electrically supply the winding wire located at the rotor using a current source located on a fixed part of the motor vehicle, it is advantageous to use a rotating collector, integral in rotation with the rotor.

[0009] This rotating collector has at least one electrical input terminal in the form of an electrically conductive ring. This terminal is electrically powered by a fixed current source, thanks to the friction of a brush on the ring, also commonly called carbon. This brush is made from a flexible metal strip, or carbon, as its name suggests.

[0010] This rotary collector has at least one output electrical terminal to which the winding wire is connected via a hooking device.

[0011] Examples of hanging devices are described in the prior art.

[0012] In particular, document FR3083026 describes a rotary collector provided with notches forming the aforementioned output terminals. The ends of the winding wire are inserted into these notches, before being blocked there using a metal ring mounted by hot crimping, which seals the notches.

[0013] This solution complicates the manufacturing cycle, particularly due to the use of high voltages required for hot crimping. In addition, since the rotating collector is a wearing part, it is necessary to make it easy to replace after-sales, without damaging the winding wire, which is not possible with hot crimping. Presentation of the invention

[0014] In order to overcome the aforementioned drawbacks of the state of the art, the present invention proposes a device for hanging the winding wire which is removable and easy to use.

[0015] More particularly, the invention provides a device for attaching a winding wire to a rotating collector which is adapted to provide an electrical connection between a rotor and a current source, the attachment device having an edge which delimits a notch through which the winding wire can be inserted, in which at least one sharpened projection is provided which is at least partly made of an electrically conductive material and which extends from the edge into the notch.

[0016] Thus, thanks to the invention, the crimping of the winding wire on the attachment device can be done cold, by clipping, simply by inserting it directly into the notch.

[0017] The notch being equipped with a sharp projection, this allows the winding wire to be mechanically held and ensures the electrical supply of this winding wire via the rotating collector, while guaranteeing easy extraction of the winding wire after-sales, with a view to possible replacement of the rotating collector.

[0018] The manufacturing cycle is thus simplified.

[0019] Other advantageous and non-limiting characteristics of the attachment device according to the invention, taken individually or in all technically possible combinations, are the following: - The notch has a bottom, and the edge is at least partially cylindrical in shape in the bottom of the notch. - The notch has a bottom with a diameter equal to the diameter of the winding wire. - The winding wire being at least partially covered with a thickness of one enamel glaze, the at least one sharp protrusion is of a length greater than the thickness of the enamel glaze. - The at least one sharp projection takes the form of a triangular prism. - The notch has a bottom and a mouth for engaging the winding wire, the edge having in the mouth two sides inclined relative to each other at an open angle opposite the bottom.

[0020] The invention also provides a rotary collector including a body comprising a circular base and a tubular part which extends from the base and on which is located at least one electrically conductive ring electrically connected by an electrically conductive bus bar to a hooking device according to the invention, the hooking device being located at the base of the rotary collector.

[0021] This rotary collector may be such that the hooking device and the bus bar connecting the hooking device to the ring are in one piece.

[0022] The invention also provides a wound rotor electric motor including a stator remaining stationary relative to a rotor rotating about an axis, the rotor comprising a main shaft and coils created by winding a winding wire, the winding wire being held on the main shaft by means of a rotating collector according to the invention.

[0023] Finally, the invention comprises a method for assembling a winding wire within a wound rotor electric motor according to the invention, the method comprising: - A fitting of the rotary collector on one end of the main rotor shaft in a final position along the rotor axis, - Clipping the winding wire onto the hanging device by inserting the winding wire into the notch of the hanging device, - A winding of the winding wire to form the coils of the wound rotor, - Clipping the winding wire onto another hanging device by inserting the winding wire into the notch of this other hanging device.

[0024] Of course, the various features, variants and embodiments of the invention may be combined with each other in various combinations to the extent that they are not incompatible or mutually exclusive. Detailed description of the invention

[0025] The description which follows with reference to the appended drawings, given as non-limiting examples, will make it clear what the invention consists of and how it can be implemented.

[0026] On the attached drawings:

[0027] [Fig.1] is a schematic representation of a motor vehicle equipped with a wound rotor electric motor according to the invention, as well as a current supply source;

[0028] [Fig.2] is a three-quarter schematic view of a rotor of the wound rotor electric motor of [Fig.l], including a rotating commutator and coils;

[0029] [Fig.3] is a schematic longitudinal sectional view of the rotary collector of the [Fig.2], on which two hanging devices appear;

[0030] [Fig.4] is a three-quarter schematic view of the hanging device of the [Fig.3] ;

[0031] [Fig.5] is a schematic side view of the hanging device of [Fig.3].

[0032] In [Fig.l], a motor vehicle 1, hybrid or electric, is schematically represented. This vehicle has a traction system, comprising at least one electric motor, powered by a current source 3.

[0033] The current source 3 can, for example, designate power electronics, such as a storage battery.

[0034] The electric motor, for its part, generates mechanical energy, in the form of a mechanical torque, from the electrical energy supplied by the current source 3. In particular, two parts can be distinguished in the electric motor, namely a rotor 20 which rotates around an axis A1, the latter being defined as the axis of the rotor in the remainder of this description, and a stator, remaining stationary relative to the chassis of the motor vehicle 1. Here, the electric motor corresponds more particularly to a wound rotor motor 2.

[0035] The rotor 20 of such a wound rotor motor 2 is shown in part in [Fig. 2]. The stator, not shown here, exerts a magnetic field on this rotor 20, for example using permanent magnets, or coils supplied with current.

[0036] The rotor 20 conventionally comprises a longitudinal body elongated along the axis A1 (not visible in [Fig. 2]), and at least two teeth 260 which project radially from the longitudinal body. The elongated body is for example tubular in shape and fitted onto a main shaft 240. The teeth 260 extend lengthwise along the axis A1 and are regularly distributed around this axis A1.

[0037] The rotor 20 contains a set of several coils 220 wound around the teeth 260 and therefore arranged radially around the axis A1 of the rotor 20, preferably with a regular angular spacing between each of the coils 220.

[0038] Here, a wound rotor motor 2 having eight teeth 260 and eight coils 220 is described.

[0039] Each coil 220 is formed from the winding of a winding wire 230. This winding, which may be helical, results in a set of adjacent turns, arranged around an axis which will be defined as the axis of the coil. All of the coils 220 can be made with the same winding wire 230. This winding wire 230 has a conductive core 231 (shown in [Fig.5]) which is made of a conductive material, such as copper.

[0040] The winding wire 230 has a nominal diameter that can be between a few tens of micrometers and a few millimeters. This nominal diameter corresponds to the diameter of the stripped wire, that is to say that of the conductive core 231, the diameter of which is less than the outer diameter of the winding wire 230.

[0041] Indeed, the winding wire 230 is at least partially covered with a layer of enamel varnish 232, making it possible, for example, to guarantee the electrical insulation between the turns of a coil 220, but also to protect the winding wire 230 from humidity or oxidation. Here, the term “winding wire” designates both the conductive core 231 and the layer of enamel varnish 232 which at least partially coats it.

[0042] A 230 winding wire is associated with a grade, which corresponds to the thickness of the 232 enamel varnish which coats it.

[0043] In the embodiment considered, the winding wire 230 is of grade 2. The thickness of the enamel varnish layer 232 is between 0.07 mm and 0.10 mm. Here, it is considered that the thickness of the enamel varnish layer 232 is fixed at 0.075 mm, within manufacturing uncertainties.

[0044] It is also considered here that the winding wire 230 has an outer diameter (i.e., including the thickness of the enamel coating 232) of 1.245 mm. The nominal diameter of the winding wire 230 is 1.17 mm in the example shown.

[0045] The flow of an electric current through the winding wire 230 from a positive terminal to a negative terminal of the current source 3 generates a magnetic field in each of the coils 220, along its own axis.

[0046] The wound rotor 20, once supplied with current, thus generates a multitude of magnetic fields (one per coil 220), oriented radially relative to the axis Al of the rotor 20.

[0047] The attraction or repulsion between the magnetic fields of the coils 220 of the rotor 20 and the magnetic field generated by the stator generates a torque which allows the rotation of the rotor 20 around its axis Al.

[0048] In order to ensure a continuous power supply to the winding wire 230 of the rotor 20, even when the latter is rotating, a rotating collector 210 is used.

[0049] This rotary collector 210 comprises a body 211 which is force-fitted onto the main shaft 240 of the rotor 20, with which it is therefore integral, via one end of the main shaft 240 of the rotor 20. The rotary collector 210 is also electrically insulated from the end of the main shaft 240.

[0050] According to variants, other methods of fixing the rotary collector 210 on the rotor 20 can be envisaged.

[0051] The rotary collector is shown in more detail in a sectional view of [Fig.3]. It has at least one circular ring 214, made of a current-conducting material. Two identical rings 214 are provided here, distinct and located at a distance from each other. These rings 214 are used to ensure the electrical supply of the rotor 20 by the accumulator battery which constitutes the current source 3. A brush, not shown here, located in contact with the external surface of each ring 214 makes it possible to ensure electrical contact between the terminals of the power electronics and these rings 214 even when the rotor 20 is rotating. Each of the rings 214 is associated with a brush.

[0052] The brush is also made of an electrically conductive material, and it is electrically connected to one of the electrical terminals of the current source 3. It therefore remains fixed relative to the chassis of the motor vehicle 1. The conduction of electricity is done via the brushes, which each rub against the external surface of one of the rings 214 of the rotating collector 210.

[0053] Thus, each of the rings 214 of the rotary collector 210 constitutes an electrical terminal of said rotary collector 210.

[0054] The rings 214 can be made of copper, while the brushes can be made of carbon or even be made of a flexible metal strip, particularly copper.

[0055] These two rings 214 correspond to a positive terminal and a negative terminal of the rotary collector 210.

[0056] The body 211 of the rotary collector 210 can be made of an insulating material, such as plastic for example.

[0057] According to one embodiment considered, the body 211 of the rotary collector 210 comprises an annular base 213 and a tubular part 218, both of revolution around the axis AL. The tubular part 218 rises from the base 213 and it carries the two rings 214.

[0058] The base 213 has an external diameter greater than that of the tubular part 218 of the body 211 of the rotary collector 210. This base 213 is placed between the coils 220 and the tubular part 218 and is fitted onto the end of the main shaft 240 of the rotor 20.

[0059] Here, as shown in [Fig. 2], the body 211 of the rotary collector 210 has two half-moon openings at the base 213, which extend into the tubular part 218; the arcs of the two half-moon openings follow the circular edge of the base 213. Thus, the base 213 is connected to the tubular part 218 by two diametrically opposed arms 212. In practice, these half-moon openings allow shoulders of the main shaft 240, also half-moon shaped, to pass through.

[0060] The body 211 of the rotary collector 210 is for example the result of an operation of overmolding on the two rings 214.

[0061] Other geometries are possible for the rotary collector 210 depending on the geometry of the wound rotor motor 2 considered, the geometry of the rotary collector 210 described previously is given by way of illustration, and is in no way limiting.

[0062] Thus, the rotary collector 210 may possibly have on one face of its base 213 in contact with the rotor 20, a stud inserting into a corresponding hole on the rotor 20. This thus makes it possible to place the rotary collector 210 in an appropriate orientation relative to the rotor 20.

[0063] The rotating collector 210 makes it possible in any case to ensure the electrical connection between a static part (here, the current source 3), and a rotating part, here, the rotor 20. The objective is in particular to supply current to the coils 220 located on the rotor 20.

[0064] The coils 220, here eight in number, of the wound rotor motor 2 are produced by winding the same winding wire 230 along several axes specific to each of the coils 220. This winding wire 230 is therefore connected by one of its ends to the positive terminal of the current source 3, and by the other of its ends to the negative terminal of the current source 3.

[0065] As shown in [Fig.2], to mechanically and electrically connect the two ends of the winding wire 230 to the electrical terminals of the rotary collector 210, i.e. to the two rings 214 which are themselves in electrical contact via brushes to the positive and negative terminals of the current source 3, the rotary collector 210 includes at least one hooking device 250. Here, the rotary collector 210 comprises two identical hooking devices 250, which are more precisely the subject of the present invention.

[0066] These attachment devices 250 are fixed at the base 213 of the rotary collector 210. Here, the two attachment devices 250 are placed so as to be diametrically opposite each other with respect to the axis AL

[0067] The hooking devices 250 make it possible to hold the ends of the winding wire 230 in a defined position, in addition to ensuring their electrical connection with the rest of the rotating collector 210. In particular, they make it possible to hold the winding wire 230 during the winding process, according to a method detailed later in this description.

[0068] The sectional view of the rotary collector 210 considered in [Fig. 3] shows the electrical connections extending between the two rings 214 and the attachment devices 250.

[0069] Here, the electrical connection between each association of ring 214 and hooking device 250 is provided by a bus bar 215. This is in the form of a bar made of a conductive metal, such as copper or aluminum for example.

[0070] In the example considered where the rotary collector 210 is provided with two rings 214, a first of the bus bars 215 connects the ring 214 linked to the positive terminal of the current source 3 to a first of the attachment devices 250. A second bus bar 215 makes it possible to join the ring 214 linked to the negative terminal of the current source 3 to a second attachment device 250.

[0071] In practice, each of the bus bars 215 has a section whose value is chosen according to the value of the current caused to circulate within the wound rotor motor 2 considered.

[0072] In one possible embodiment, the attachment devices 250 are made at least partially of an electrically conductive material, such as copper or aluminum.

[0073] Thus, it is possible, in this embodiment, for the attachment device 250 to be in one piece with the bus bar 215 to which it is connected. In other words, the attachment device 250 and the bus bar 215 form a monolithic assembly, shaped from a single material, with no demarcation between the two elements making up the assembly.

[0074] In practice, the attachment device 250 corresponds to the part which emerges from the body 211 of the rotary collector 210 at the level of its base 213.

[0075] This embodiment is shown in [Fig. 3], where each hooking device 250 is in the extension of the associated bus bar 215.

[0076] A detailed view of a hooking device 250 according to the invention is shown in [Fig.4].

[0077] This attachment device 250 comprises a flat plate 251 which rises from the lateral face of the base 213, orthogonally to the axis A1, and which has two lateral edges and a free end edge. It also comprises a flat tab 252 which extends from one of the lateral edges of this flat plate 251, orthogonally to the latter. It extends over only part of the height of this flat plate. It is more precisely located at a distance from the body 211 of the rotary collector 210 but extends to the free end edge of the flat plate 251.

[0078] In the embodiment described in [Fig.4], the flat plate 251 therefore constitutes one end of the bus bar 215.

[0079] The tab 252 has two main faces 253A, 253B, connected to each other by an edge 253C whose top is flat and located opposite the plate 251.

[0080] The two main faces 253A, 253B of the tongue 252 extend parallel to the axis A1 of the rotor 20. Thus, in the embodiment mentioned above, where the attachment device 250 is integral with the bus bar 215, the tongue 252 is contained in a plane perpendicular to the bus bar 215, and the plate 251 described above constitutes one end of this bus bar 215.

[0081] The tab 252 has a notch 254A, 254B hollowed out in the top of its edge 253C, through which the winding wire 230 (when it is oriented perpendicular to the axis Al) can be inserted in a direction parallel to the axis Al.

[0082] Thus, the ends of the winding wire 230 are contained in a plane perpendicular to the axis A1 of the rotor, this plane passing through the coils 220 of the rotor 20.

[0083] The notch 254A, 254B is delimited by an edge 255.

[0084] The edge 255 has a complex surface, which may be partially curved or planar; this surface may also take multiple shapes. A side view of the hanging device 250 is shown in [Fig.5].

[0085] The notch 254A, 254B has a bottom 256 and opens outwards through a mouth 257.

[0086] In one embodiment, illustrated in Figures 3, 4, and 5, the portion of the edge 255 of the notch 254A, 254B which delimits the bottom 256 describes an arc of a circle.

[0087] Preferably, the arc-of-circle has a diameter close to the outer diameter of the winding wire 230.

[0088] The arc of a circle thus has a diameter between a few tens of micrometers and a few millimeters.

[0089] In the embodiment considered here, the winding wire 230 used having an outside diameter of 1.245 mm, the diameter of the arc of a circle described by the bottom 218 also has a diameter of 1.245 mm.

[0090] The arc of a circle described by the part of the edge 255 delimiting the bottom has a curvilinear length at least equivalent to half the circumference of the winding wire 230.

[0091] Preferably, this arc of a circle has a curvilinear length equivalent to three-quarters of the circumference of the winding wire 230. This arc of a circle length is chosen so as to ensure good retention of the winding wire 230 within the notch 254A, 25B, while allowing its insertion / removal easily (typically manually, without tools).

[0092] Similarly, the thickness of the tab 252 is chosen so as to maintain the tab 252 in the elastic range of the material of which it is composed during insertion of the wire. This thickness therefore varies from a few fractions of a millimeter to a few millimeters.

[0093] Here, the tab 252, as well as the rest of the hooking device 250, are composed of copper, or another conductive metal.

[0094] Thus, in one embodiment, the tab 252 has a thickness of 0.9 mm.

[0095] Ideally, the mouth 257 of the notch 254A, 254B has a shape facilitating the insertion of the winding wire 230.

[0096] The mouth 257 has two sides, delimited by two portions of the edge 255 which are opposite each other. These portions of the edge 255 are here flat, and inclined relative to each other. The spacing defined between these two portions of the edge 255 has a maximum value at the entrance to the notch 254A, 254B, which corresponds to the mouth 257, before gradually decreasing towards the bottom 256 of the notch 254A, 254B.

[0097] For example, these two portions of the edge 255 delimiting the mouth 257 can rest on two intersecting planes, according to a V.

[0098] The maximum spacing between the two sides of the mouthpiece 257 is chosen to be greater than the outer diameter of the winding wire 230.

[0099] Here, in the embodiment considered, given that the outer diameter of the winding wire 230 is 1.245 mm, the maximum spacing between the sides of the mouthpiece 257 is therefore 1.40 mm.

[0100] Between the mouth 257 and the bottom 256, the edge 255 of the notch 254A, 254B may be rounded in order to facilitate the insertion of the winding wire 230 into the notch 254A, 254B.

[0101] Furthermore, in order to prevent the winding wire 230 from being dislodged too easily from the notch 254A, 254B once inserted, the minimum spacing between the two sides of the mouth 257 is chosen to be slightly smaller than the outside diameter of the winding wire 230, so that slight pressure must be exerted to insert or extract the end of the winding wire 230 from the attachment device 250.

[0102] In one possible embodiment, the minimum spacing between the two sides forming the mouth 257 is 0.9 mm.

[0103] In order to electrically connect the winding wire 230 (which is covered with an insulating varnish) to the attachment device 250, at least one sharp projection 258 is arranged on the bottom 256 of the notch 254A, 254B. Several are provided here.

[0104] These sharp protrusions 258 are made of an electrically conductive material, such as copper for example.

[0105] The number of sharpened projections 258 can be chosen depending on the value of the current supplying the winding wire 230.

[0106] For example, here it is eight sharp projections 258 which are represented in the embodiment of figures 4 and 5.

[0107] These eight sharp projections 258 rise radially from the edge 255 of the bottom 256 of the notch 254A, 254B (the term radially referring to the axis of the arc-of-circle described previously).

[0108] The length of the sharpened projections 258 is chosen so as to be greater than the thickness of the enamel varnish 232 of the winding wire 230, which is shown in cross-section in [Fig. 5]. This length is chosen so that the sharpened projections 258 can pierce the enamel varnish layer 232 without deform, and thus bring into electrical contact the conductive core 231 of the winding wire 230 and the sharpened projections 258, the latter being electrically linked to the rest of the attachment device 250.

[0109] The length of a sharpened projection 258 must not, however, exceed the radius of the winding wire 230.

[0110] Thus, in the embodiment considered, the length of a sharpened protrusion 258 is greater than 0.075 mm, but less than 0.7 mm. Here, the length of a sharpened protrusion 258 is set at 0.1 mm.

[0111] In one possible embodiment, the sharpened projections 258 take the shape of a triangular prism.

[0112] The sharpened projections 258 not only serve to electrically connect the winding wire 230 to the terminals of the rotary commutator 210 via the hooking device 250, but also contribute to holding the winding wire 230 within the notch 254A, 254B.

[0113] The insertion of the winding wire 230 may be reversible or not, depending on the shape of the sharpened projection 258.

[0114] In the embodiment discussed above, the selection of sharpened protrusions 258 in the shape of a triangular prism allows both insertion and removal of the end of the winding wire 230.

[0115] In other possible embodiments, the sharpened protrusions 258 may take various shapes (e.g., harpoon point shapes) to achieve certain functions, such as preventing the winding wire 230 from becoming dislodged.

[0116] In one possible embodiment, the sharpened projections 258 form a monolithic assembly with the attachment device 250. The assembly is then made from the same electrically conductive material, such as copper for example.

[0117] According to a possible embodiment, the bus bar 215, the hooking device 250 and the sharpened projections 258 are made in one piece, from the same strip composed of a conductive metal, such as copper for example.

[0118] This assembly can, for example, be manufactured by stamping a copper strip.

[0119] The end of the bus bar 215 opposite the hooking device 250 is then electrically connected to the corresponding ring 214, in particular by means of welding for example.

[0120] This assembly is then incorporated into the body 211 of the rotary collector 210, in particular by injection overmolding, in a plastic and electrically insulating material.

[0121] Other means of manufacturing a rotary collector 210 according to the invention are possible, and are left to the discretion of the person skilled in the art.

[0122] The invention also relates to a method for assembling a winding wire 230 within a wound rotor motor 2 using a rotary collector 210 comprising at least one attachment device 250 as mentioned above.

[0123] The first step of this method consists of fitting the rotary collector 210 onto the main shaft 240 of the rotor 20, via one end of the main shaft 240, to what may possibly be its final position.

[0124] Then, a second step of this process consists of cold crimping one of the two ends of the winding wire 230 onto one of the attachment devices 250 located on the base 213 of the rotary collector 210.

[0125] Cold crimping, which consists more precisely of clipping the winding wire 230 within the attachment device 250, is carried out by engaging the end of the winding wire 230 in the mouth 257 of the notch 254A, before exerting pressure so that the winding wire 230 is housed in the bottom 256 of the notch 254A. The end of the winding wire 230 is then contained in a plane perpendicular to the axis AL

[0126] Particular attention will be paid to ensuring that the sharp projections 258 actually pierce the thickness of the enamel varnish 232.

[0127] A third step of this method consists of producing the coils 220 of the wound rotor 20 using the winding wire 230 held at one of its ends by a hooking device 250. The coils are produced using a dedicated machine, which is not the subject of the present invention.

[0128] The fourth step of this method consists of fixing, via cold crimping, in particular clipping, the remaining end of the winding wire 230 on a second of the attachment devices 250, in the associated notch 254B.

[0129] Of course, the foregoing description has been given by way of example only and does not limit the scope of the invention, which would not be exceeded by replacing the various elements with any other equivalents. Furthermore, the various features, variations, and / or embodiments of the present invention may be combined with each other in various combinations.

Claims

Claims

1. A device (250) for hooking a winding wire (230) onto a rotating collector (210) which is adapted to provide an electrical connection between a rotor (20) and a current source (3), said hooking device (250) having an edge (255) which delimits a notch (254A, 254B) through which said winding wire (230) can be inserted, characterized in that it comprises at least one sharpened projection (258) which is at least partly made of an electrically conductive material and which extends from said edge (255), into said notch (254A, 254B).

2. A hanging device (250) according to claim 1, wherein the notch (254A, 254B) having a bottom (256), the edge (255) is at least partially cylindrical in shape in the bottom (256) of the notch (254A, 254B).

3. Hanging device (250) according to one of claims 1 or 2, in which the notch (254A, 254B) has a bottom (256) of diameter equal to the diameter of the winding wire (230).

4. Hanging device (250) according to one of claims 1 to 3, wherein, the winding wire (230) being at least partially covered with a thickness of an enamel varnish (232), said at least one sharpened projection (258) is of a length greater than the thickness of said enamel varnish (232).

5. A hooking device (250) according to one of claims 1 to 4, wherein said at least one sharpened projection (258) takes the form of a triangular prism.

6. Hanging device (250) according to one of claims 1 to 5, in which the notch (254A, 254B) has a bottom (256) and a mouth (257) for engaging the winding wire (230), the edge (255) having in said mouth (257) two sides inclined relative to each other by an open angle opposite the bottom (256).

7. Rotary collector (210) including a body (211) having a circular base (213) and a tubular portion (218) which extends from the base (213) and on which is located at least one electrically conductive ring (214) electrically connected by an electrically conductive bus bar (215) to a hooking device (250) according to one of claims 1 to 6, said hooking device (250) being located at the base (213) of said rotary collector (210).

8. A rotary commutator (210) according to claim 7, wherein the hooking device (250) and the bus bar (215) connecting said hooking device (250) to the ring (214) are integral.

9. A wound rotor electric motor (2) including a stator remaining stationary relative to a rotor (20) rotating about an axis (A1), said rotor (20) comprising a main shaft (240) and coils (220) created by winding a winding wire (230), said winding wire (230) being held on said main shaft (240) by means of a rotating commutator (210) according to claim 7 or 8.

10. Method of assembling a winding wire (230) within a wound rotor electric motor (2) according to claim 9, comprising: - a fitting of the rotary collector (210) on one end of the main shaft (240) of the rotor (20) at a final position along said axis (Al), - clipping the winding wire (230) onto the attachment device (250) by inserting the winding wire (230) into the notch (254A) of said attachment device (250), - a winding of the winding wire (230) to form the coils (220) of the wound rotor (20), - clipping the winding wire (230) onto another attachment device (250), by inserting the winding wire (230) into the notch (254B) of said other attachment device (250).

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