In situ and ex situ winding process for electrical machine, and associated electrical machine

Abstract

The invention relates to a winding method for placing an electrically conductive wire (3, 3P) around a core of a tooth (100) of an electrical machine. According to the invention, in situ winding allows the winding of a segment of the electrically conductive wire around the core in order to form an in situ coil (5), then ex situ winding, which consists of winding another segment of the electrically conductive wire on a template, in order to form an ex situ coil (7) adapted to be fitted around the in situ coil produced. A report of the ex situ coil around the in situ coil then allows the formation of an assembled coil (9). Figure for the abstract: Fig. 7

Description

Title of the invention: In situ and ex situ winding method for an electrical machine, and associated electrical machine Technical field of the invention

[0001] The present invention relates generally to electrical machines.

[0002] It relates more particularly to a method of in situ and ex situ winding of a rotor and / or a stator for an electrical machine.

[0003] It also relates to an electrical machine comprising a rotor and / or a stator comprising a coil whose winding is done according to such a method.

[0004] The invention finds a particularly advantageous application in axial flux electric motors for electric or hybrid motor vehicles. State of the art

[0005] An electric machine is an electromechanical device allowing the conversion of electrical energy into mechanical energy and / or vice versa. For example, electric or hybrid cars are equipped with such electric machines (then commonly called "electric motors"), powered by a current source, and allowing the driving of a traction or propulsion system.

[0006] These electrical machines usually have a part remaining static relative to the rest of the vehicle, corresponding to a stator, while a rotor is set in motion relative to the stator.

[0007] The movement of the rotor relative to the stator(s) in an electrical machine is due to an attraction and / or a repulsion between magnetic fields constituting magnetic poles generated within the rotor and the stator. In the case of an axial flux machine, the magnetic fields are oriented longitudinally relative to an axis of rotation of the rotor, while in a radial flux machine, the magnetic fields extend radially from the axis of rotation.

[0008] A conventional stator of an axial flux electrical machine comprises a generally disc-shaped yoke, which is centered on the axis of rotation of the rotor, and teeth which are distributed on a main face of the yoke, around the axis of rotation, opposite the rotor. Each tooth has a main part (called a "core"), which is bordered at its apex by a pair of lateral edges (called "isthmuses"). These teeth are separated from each other by initially empty notches. These notches are then at least partly filled by a pair of coils of electrically conductive wire, each of the teeth in fact carrying a winding around its core. The circulation of electric currents within the coils generates the magnetic fields allowing the rotor to move.

[0009] Isthmuses are necessary to improve the magnetic performance of the electrical machine. Indeed, these isthmuses advantageously have a shape that makes it possible to smooth the interaction of the magnetic fields of the rotor and the stator. The attraction and / or repulsion of the different magnetic poles is thus done smoothly, thus causing the rotor to rotate smoothly around the stator. The rotation speed remains constant, even at low speed, improving the driving experience.

[0010] Their presence on the cores, however, has the disadvantage of complicating the automated winding process of the teeth. It is understood that they hinder the passage of the winding needle of the electric wire between the teeth.

[0011] It is then known in the literature to start by machining the yoke and the cores of the teeth that it carries (without the isthmuses), to proceed with the winding of the different coils around the cores, then to add to the top of each core a magnetic sintered material ("Soft magnetic composites", according to the Anglo-Saxon term), in order to form the pair of isthmuses which surmount it.

[0012] This solution, although making it possible to obtain a filling rate of the notch by the coils deemed satisfactory, nevertheless degrades the magnetic performance of the stator, compared to the case where the yoke, the cores and the isthmuses are machined from one piece. Presentation of the invention

[0013] In order to overcome the aforementioned drawbacks of the state of the art, the present invention proposes a method of winding the teeth of the stator partly in situ (around the tooth) and partly ex situ, the part wound ex situ then being attached to the part wound in situ.

[0014] More particularly, the invention proposes a winding method for placing an electrically conductive wire around a core of a tooth of an electrical machine, as defined in the introduction, in which in situ winding is provided for winding a segment of the electrically conductive wire around the core in order to form an in situ coil therein, followed by ex situ winding, consisting of winding another segment of the electrically conductive wire on a template, in order to form an ex situ coil adapted to be fitted around the in situ coil, then a connection of the ex situ coil around the in situ coil, forming an assembled coil.

[0015] Thus, thanks to the invention, the presence of the lateral edges, that is to say the isthmuses, surmounting the teeth is no longer a source of hindrance for the passage of automated winding tools, since an ex situ coil is produced outside the tooth, before being mechanically connected with the in situ coil. It is thus possible to obtain a filling rate of the notch close to the filling rate obtained on teeth initially devoid of lateral edges.

[0016] The proposed method thus makes it possible to avoid having to compromise between the filling rate of the notches, the use of teeth provided with isthmuses and shaped in a single piece and the manufacturing cost. These first two aspects both contribute to improving the performance of the electric machine, in particular by increasing the admissible current density and therefore the power of the machine, while ensuring smooth rotation of the rotor around the stator, while the third aspect is advantageous for industrial-scale production.

[0017] This method is particularly advantageous for winding an axial flux electric machine, given the reduced size of the notches between the teeth.

[0018] Other advantageous and non-limiting characteristics of the in situ and ex situ winding method according to the invention, taken individually or in all technically possible combinations, are the following: - after the ex situ coil has been reported around the in situ coil, a forming of the ex situ coil on the in situ coil is planned, - at least one coil head guide is brought into contact with the tooth, before the in situ winding step, the guide is provided with at least one hollow, and the ex situ coil has an internal dimension greater than an external dimension of the in situ coil, the difference between the internal dimension of the ex situ coil and the external dimension of the in situ coil is equal to a mounting clearance; during the forming, a part of the in situ coil is deformed in contact with at least a part of the hollow, and the ex situ coil is deformed so as to be in contact with the in situ coil, in order to reduce the mounting clearance, - the ex situ coil has an internal dimension greater than an external dimension of the in situ coil, the difference between the internal dimension of the ex situ coil and the external dimension of the in situ coil is equal to a mounting clearance, after having engaged the ex situ coil around the in situ coil along a mounting axis, a positioning step is provided consisting of moving the ex situ coil radially relative to the mounting axis to bring the in situ coil and the ex situ coil into contact with each other on one side of the in situ coil so as to leave the mounting clearance on a side radially opposite to the side previously mentioned above, - the assembled coil comprising superimposed layers of electrically conductive wires, the electrically conductive wires of one layer are placed in a staggered manner relative to the electrically conductive wires of the layer below and / or above, - the electrically conductive wire segment of the ex situ winding being initially separated from the electrically conductive wire segment of the at least one in situ winding, the electrically conductive wire segment of the at least one in situ winding and the electrically conductive wire segment of the in situ winding are electrically connected after the reporting step, - the electrically conductive wire segment of the in situ winding and the electrically conductive wire segment of the ex situ winding are electrically bonded before and during the in situ winding, - the template having a variable size, after the ex situ winding stage, it is planned to reduce the size of the template, - the electrical machine comprising two neighboring teeth around which coils are attached in ex situ, after the step of attaching the coils ex situ, at least one coil wedge is inserted into a residual space located between the coils ex situ.

[0019] The invention also relates to an electrical machine comprising at least one yoke, from which at least one tooth rises around which an assembled coil is wound, this assembled coil being produced according to a winding method as mentioned above.

[0020] 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

[0021] 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.

[0022] In the attached drawings:

[0023] [Fig-1] is a schematic perspective view of a part of a machine stator electric, including in particular a cylinder head and teeth;

[0024] [Fig.2] is a flowchart illustrating the steps of a method according to the invention allowing winding of the teeth of the yoke of [Fig.l].

[0025] [Fig.3] is a top view schematically representing two neighboring teeth of the stator of [Fig.l], after installation of two coil head guides and slot bottom papers, and after in situ winding of one of the teeth according to the method of [Fig.2],

[0026] [Fig.4] is a profile view schematizing the two teeth of [Fig.3].

[0027] [Fig.5] illustrates an ex situ winding step according to the method of [Fig.2], carried out around a template, located at a distance from the stator of [Fig.l].

[0028] [Fig.6] is a schematic view seen from above of the two teeth of figures 3 and 4 after a report and positioning of the coil carried out on the template of [Fig.5] on one of the teeth and after forming the two coils.

[0029] [Fig.7] is a schematic side view of a tooth during the step of reporting, and a tooth after electrical connection, thus forming an assembled coil, these two steps being carried out in accordance with the process of [Fig.2]

[0030] [Fig.8] illustrates a second embodiment of the method of [Fig.2].

[0031] In [Fig.l], a part of a stator 1 is shown schematically, which is itself- even intended to be integrated into an electric machine, here axial flux. This axial flux electric machine corresponds in this case to a motor, making it possible to propel or tow an electric or hybrid vehicle. Such an electric machine comprises at least one rotor and at least one stator.

[0032] In practice, it may comprise a rotor located between two stators, generally identical. The interaction between magnetic poles of the stator and the rotor makes it possible to set the latter in rotation around a longitudinal axis Al, which therefore corresponds to an axis of rotation.

[0033] This stator 1 comprises in particular a yoke 10, on which a plurality of teeth 100 stand.

[0034] As shown in [Fig.l], the cylinder head 10 essentially has a disc shape centered on the longitudinal axis A1. However, for its attachment to an output shaft of the engine, it has a central opening 14 of generally circular shape, which is delimited by an internal face 16 of the cylinder head 10. Thus, the cylinder head 10 forms a thick ring centered on the axis of rotation corresponding to the longitudinal axis A1. As a variant, the cylinder head 10 could have a polygonal shape, for example with as many sides as it has teeth.

[0035] The internal face 16 is opposite an external face 18 of the yoke 10, the external face 18 delimiting an external perimeter of the disc therefore corresponding to its periphery. The internal face 16 as well as the external face 18 are here cylindrical of revolution around the longitudinal axis AL

[0036] In the remainder of the description, the terms “internal” and “external” are defined with reference to the orientation of the elements relative to the central opening 14 of the cylinder head 10. Thus, the term “internal” designates faces, or portions of elements facing towards the central opening 14 bordering the longitudinal axis A1, delimited by the internal face 16, while conversely, the term “external” designates faces or portions of elements facing in the opposite direction, towards the periphery of the cylinder head 10, delimited by the external face 18 of the cylinder head 10.

[0037] The different directions and orientations of the elements mentioned in the present description are defined as a function of the orientation of the yoke 10 as shown for illustrative purposes in [Fig.l], even if in practice, the axis of rotation of an electrical machine in a vehicle is rather oriented horizontally.

[0038] The yoke 10 and the teeth 100 which are integral with it, have a magnetic circuit function. They are preferably made in one piece, for example by winding around the longitudinal axis A1 a single sheet metal plate cut with crenellations. This sheet metal plate is wound in a spiral, the cut crenellations being adapted to form, after winding, the teeth 100.

[0039] The ferromagnetic sheet used in this regard may, for example, be made of non-grain-oriented magnetic steel. Alternatively, it may also be made of grain-oriented magnetic steel.

[0040] The teeth 100 stand on the yoke 10, and rise parallel to the longitudinal axis AL. They are distributed with a regular spacing between each tooth 100 on the ring formed by the yoke 10.

[0041] For each of the teeth 100, a radial axis A2 is defined. This radial axis A2 corresponds to an axis perpendicular to the longitudinal axis A1, and passing through a geometric middle of the tooth 100 on the external face 18 of the yoke 10.

[0042] Similarly, for each of the teeth 100, an ortho-radial axis A3 is defined as being perpendicular to both the longitudinal axis A1 and the radial axis A2. In practice, this ortho-radial axis A3 is generally parallel to a tangent drawn in the middle of the tooth 100 at the level of the external face 18.

[0043] Here, there are sixteen teeth 100 which stand on the yoke 10. Alternatively, a stator 1 provided with eighteen teeth 100 is also conceivable, or any other specification of number of teeth 100 deemed suitable.

[0044] Each of these teeth 100 has a solid central part called core 102. The core 102 extends in height along the longitudinal axis A1 from an upper face of the yoke 10 to a top of the tooth 100.

[0045] Figures 3 and 4 provide a more detailed representation of the teeth 100 seen from above and in profile.

[0046] Seen from above, each core 102 generally has the shape of a right prism, with a trapezoidal section in a plane containing the radial axis A2 and the ortho-radial axis A3. In addition, each core 102 has a plane of radial symmetry, corresponding to a plane containing the radial axis A2 and the longitudinal axis AL.

[0047] Alternatively, the core 102 could have other shapes, devoid of a radial symmetry plane for example.

[0048] The core 102 therefore has four vertical faces standing parallel to the longitudinal axis A1, and extending from the upper face of the yoke 10 to the top of the tooth 100.

[0049] Two of the vertical faces of the core 102 are oriented opposite each other, one towards the central opening 14, and is therefore called the internal face 122 of the core 102; while the other is oriented opposite, and is therefore called the face external 132. These two faces are connected by two so-called lateral faces 142.

[0050] The teeth 100 are spaced apart such that a notch 200, initially empty, is formed between each pair of neighboring teeth 100, for example between a tooth 100A and a tooth 100B.

[0051] Each of the cores is here surmounted by a pair of lateral edges 104, at the level of the top of the tooth 100.

[0052] These lateral edges 104, also commonly called “isthmus” or “notch beaks” in usual technical language, each extend along one of the lateral faces 142 of the core, and form projections on these lateral faces 142 in the direction of the ortho-radial axis A3.

[0053] As shown in [Fig.4], each of these lateral edges 104 has a triangular section. Each lateral edge 104 therefore has an upper face which extends the top of the tooth 100, and an inclined lower face called the lower slope 124. Its thickness therefore decreases from the core 102 until it forms an edge 134.

[0054] The distance between the teeth and the width of the lateral edges 104 are chosen such that a gap is formed between the edges 134 of the lateral edges 104 of two neighboring teeth 100.

[0055] Here, the shape of the pair of lateral edges 104 is chosen to be identical, except for plane symmetry.

[0056] Thus, in summary, the assembly composed of the core 102 capped by a pair of lateral edges 104 (or isthmuses), forms the tooth 100.

[0057] Advantageously, the yoke 10 and the teeth 100 which project therefrom are monobloc, that is to say made from a single piece in the same material, as described above in the description. Thus, even if the different elements have been described separately, the yoke 10, the teeth 100, each formed from a core 102 and a pair of lateral edges 104, are made without electrical discontinuities. The magnetic performances of this monobloc assembly are therefore improved compared to a stator of which certain elements would be added by the addition of magnetic material.

[0058] Nevertheless, the subject of the invention also applies to yokes 10 and teeth 100 machined using other methods, for example by adding the lateral flanges 104 surmounting the cores 102 subsequently, by adding sintered material such as SMC (soft magnetic composite). This nevertheless has the disadvantage of introducing an additional air gap between the core 102 and the pair of lateral flanges 104, degrading the magnetic performance of the electric machine, as mentioned previously.

[0059] A segment of electrically conductive wire 3 is used to form a coil around each of the teeth 100 of the yoke 10, thereby filling the initial space initially empty notches 200 by layers of electrically conductive wires 3 wound on top of each other. The initially empty space forming the notch 200 is therefore filled by a pair of coils from neighboring teeth 100.

[0060] The coil is notably made using a segment of copper wire, due to its good electric current conduction properties. It can also be a wire made of any other electrically conductive metal.

[0061] Here, the electrically conductive wire segment is a wire with a diameter of the order of a millimeter. In particular, in the embodiment considered, the electrically conductive wire 3 has a diameter of 1.4 millimeters.

[0062] In addition, the electrically conductive wire segment 3 is covered with a layer of enamel varnish, used for electrical insulation of the superimposed layers of wires. This enamel varnish also makes it possible to protect the electrically conductive wire segment 3 from humidity or oxidation.

[0063] The production of a coil around each of the teeth 100 is done according to the method detailed in the remainder of the description. This method is illustrated by the flowchart of [Fig.2],

[0064] The application of the method is first described for a given tooth 100. The extension to the winding of all the teeth 100 of the stator 1 is detailed in a second step.

[0065] Firstly, during a step E10, exposed surfaces of each of the teeth 100, corresponding to the lateral faces 142 of the core 102, and to the lower slopes 124 of the pair of lateral edges 104, as well as an area of ​​the upper face of the yoke 10, corresponding to the notch 200 and located between a pair of teeth 100, are covered with an envelope 4. This envelope 4 is made of a non-magnetic and electrically insulating material, such as for example a plastic resin material, or an adhesive material. Here it is a polyimide insulating film, also called “NOMEX paper”.

[0066] This envelope 4 is usually referred to as “slot backing paper”, since it lines all of the surfaces delimiting a notch 200, and thus makes it possible to electrically insulate each tooth 100 from the coil which surrounds it.

[0067] During this preparation step E10, coil head guides 42, 43 are placed on each of the teeth 100.

[0068] More precisely, as shown in [Fig. 3], on a given tooth 100, a first coil head guide 42 called internal is placed against the internal face 122 and a second coil head guide 43 called external is placed against the external face 132.

[0069] However, the installation of a single coil head guide, on one side or the other of the tooth 100 can also be envisaged according to another embodiment.

[0070] The coil head guides 42, 43 therefore all have a flat face, in contact with the inner face 122 or the outer face 132 of the core 102.

[0071] A second face of the coil head guide 42, 43 has a curved surface, oriented in the direction of the central opening 14, or in the direction of the periphery of the yoke 10.

[0072] The coil head guides 42, 43 advantageously have hollow patterns on their curved surface, which facilitate the production of a first layer of electrically conductive wires 3 at the start of winding, by guiding the positioning of the wire. It is also from this advantage that they derive their name.

[0073] Each coil head guide 42, 43 also has a hollow 400, illustrated in [Fig. 6]. This hollow 400 is centered on the curved surface and extends along the longitudinal axis A1. This hollow 400 has a depth along the radial axis A2 whose value varies between 0.5 millimeters and 5 millimeters; while the width of the hollow 400 varies between 7 millimeters and 40 millimeters, and its length extends for example over the entire height of the coil head guide 42, 43. The exact dimension of the hollow 400, as well as its shape, is left to the judgment of the person skilled in the art, according to considerations which are explained in the remainder of the description.

[0074] The hollow 400 has a concave profile seen in the plane containing the radial axis A2 and the ortho-radial axis A3.

[0075] Alternatively, only one of the two coil head guides 42, 43 has a domed surface having a hollow 400 in its center.

[0076] The coil head guides 42, 43 are made by plastic injection molding. Ideally, the coil head guides 42, 43 are electrically insulating and non-magnetic.

[0077] A tooth, as obtained at the end of this preparation step E10, is illustrated in [Fig.3] by tooth 100A.

[0078] In the context of the method, a first winding step is carried out around the core 102 of each of the teeth 100 of the stator 1 until a coil is formed. This first winding is referred to as “in situ winding” E20 in the remainder of the description, and the coil thus obtained is referred to as “in situ coil” 5.

[0079] For a given tooth 100, a segment of electrically conductive wire 3 is wound around the core 102 using a first suitable winding tool.

[0080] This is a needle winding machine 60 (“needle winding machine”, according to English terminology), where the tooth 100 remains static and a needle unwinds the wire, here copper, around its core 102, starting from the internal or external coil head guide 42, 43. In the example described, the starting point of the in situ winding is at the level of the internal coil head guide 42.

[0081] The electrically conductive wire segment 3 has two ends, a head 31 and a tail 32 visible in [Fig.3].

[0082] The end located at the starting point of the winding is designated as the head 31 of the electrically conductive wire segment 3. The opposite end is designated as the tail 32 of the electrically conductive wire segment 3.

[0083] Thanks to the needle winding machine 60, the electrically conductive wire segment 3 is wound regularly, for example by making a first loop around the core 102 of the tooth 100, before making a second loop, offset in height and adjoining the first loop, and so on.

[0084] These loops wound around the core 102 to form a coil are also called “turns”.

[0085] Thus, the succession of turns of electrically conductive wire 3 wound by the switch winding machine rises in tight rows around the core 102. Ideally, each turn is in contact with the previous one.

[0086] Viewed in a section along a plane containing the ortho-radial axis A3 and the longitudinal axis A1, as illustrated in [Fig.4], this first layer of the in situ coil 5 has a row aligned vertically on one side and the other of the section of the core 102. Each of the turns appears here as a circular section of the electrically conductive wire 3. Other sections of electrically conductive wire are also possible, depending on the wire used.

[0087] These two rows extend for example from the main face of the cylinder head 10, in the bottom of the notch 200, to the lower slope 124 of the pair of lateral edges 104.

[0088] Once arrived at one end, here, the lower slope 124 of the pair of lateral edges 104, a second layer of turns of electrically conductive wires 3 is superimposed on the second layer. For this, it is provided that the needle winding machine 60 winds a series of turns of conductive wires in a downward movement, from the lower slope of the pair of lateral edges 104 to the bottom of the notch 200.

[0089] Here, a winding in “ordered wires” is provided in order to maximize a filling rate of the notch 200. This filling rate is for example defined in a plane containing the longitudinal axis A1 and the ortho-radial axis A3, as the sum of the conductive sections of the electrically conductive wire 3 and related to a projection of a surface of the notch 200 in this plane.

[0090] This type of winding, also called “orthocyclic” winding, according to the English terminology (orthocyclic winding), consists of placing the electrically conductive wire 3 of each turn, in a groove formed between two adjacent turns of the lower layer.

[0091] In other words, the electrically conductive wires 3 of a given layer are placed in a staggered pattern relative to the electrically conductive wires 3 of the layer of below.

[0092] However, any other suitable winding geometry is possible within the framework of the present disclosure, such as for example a loose winding, corresponding to the Anglo-Saxon notion of jumble winding or wild winding, which may be a preferred winding geometry due to its low cost. Similarly, the number of turns of electrically conductive wires wound around the core 102 for a layer is left to the discretion of those skilled in the art.

[0093] The following layers of the in situ coil 5 are produced according to the same principle with an alternation of upward and downward movements between the bottom of the notch 200 and the lower slope 124 of the pair of edges 104.

[0094] Here, four layers of superimposed wires are wound around the core 102 in order to form the in situ coil 5. The number of layers is here chosen so that the last layer, called outer layer 52, and shown in [Fig.4], reaches the edge 134 of the pair of lateral flanges 104.

[0095] The number of turns of electrically conductive wire 3 in each layer is for example identical from one layer to another, or a variable number of turns can be produced within each layer, in order to best adapt to the geometry of the space available in the notch 200.

[0096] For example, here, an increasing number of turns is wound within each layer of the in situ coil 5, in order to adapt to the beveled shape of the pair of lateral flanges 104 overhanging the notches 200.

[0097] This in situ winding step E20 results in a compact coil around the core 102 of the tooth 100. In fact, a space between the rows of electrically conductive wire is left at a minimum.

[0098] A tooth 100B, as obtained after the in situ winding step E20, is shown in [Fig.3] and in [Fig.4].

[0099] According to the method, the in situ coil 5 is directly produced on its final location (i.e. on the tooth 100) for the lifetime of the electric machine.

[0100] In addition, the in situ coil 5 has an external shape 54, matching that of the volume around which it was made. Here, seen from above, as in [Fig.3], via a section along a plane containing the radial axis A2 and the ortho-radial axis A3, the in situ coil 5 has a slightly rounded trapezoidal external shape 54 around the core 102 and the coil head guides 42, 43. This external shape 54 is associated with an external dimension, grouping together a set of dimensions making it possible to geometrically describe this shape.

[0101] In this first embodiment of the method, the tail 32 of the electrically conductive wire segment 3 obtained at the end of the in situ winding E20 is mechanically connected to the coil head guide, ideally to the external coil head guide 43. This is the case in particular in [Fig.4], for the in situ coil 5 produced around the tooth 100B. Thus, it is planned in the in situ winding step E20 to start and interrupt the winding of the electrically conductive wire 3 in suitable positions.

[0102] Similarly, the length of the electrically conductive wire segment 3 used is intended to be sufficiently long to allow this electrical connection to the external coil head guide 43.

[0103] Preferably, the electrically conductive wire segment 3 is mechanically and electrically connected to the coil head guide 42, 43. For this, a metallic and electrically conductive bar 430 is for example overmolded in the external coil head guide 43. In particular, this is a copper bar overmolded within the coil head guide 43.

[0104] The connection, which also ensures the mechanical holding of the electrically conductive wire segment 3 on the stator 1, is made by hot crimping, by soldering, by laser welding, or any other suitable technique.

[0105] Alternatively, the tail 32 of the electrically conductive wire segment 3 is only mechanically fixed to the coil head guide 42, 43, for example using a hook, a notch, or any other means deemed appropriate by those skilled in the art.

[0106] This in situ winding E20 can be carried out around each tooth 100. At this stage, the notch 200 between each pair of neighboring teeth is only partially filled, the magnetic performance of the associated electrical machine is therefore not optimal. Nevertheless, the continuation of the in situ winding E20, in particular by the needle winding machine 60, is not possible since it would be hindered by the spatial congestion generated by the presence of the pairs of lateral edges on the teeth 100. Indeed, the passage of the winding machine, here, of the needle winding machine 60, requires a minimum space of the order of a few millimeters, more precisely, approximately 4 millimeters.

[0107] To overcome this constraint, it is proposed in the method to continue filling the notch by adding a second coil, which corresponds to an ex situ coil 7 produced at a distance from the tooth 100.

[0108] Indeed, advantageously, it is proposed here to carry out a second winding, called ex situ winding E30 using another segment of electrically conductive wire 3P, around a template 8 located at a distance from the tooth 100, then to bring this ex situ coil 7 around the in situ coil 5.

[0109] Thus, thanks to this method proposing two-stage winding, the spatial constraint linked to the space required for the passage of the winding machine is circumvented.

[0110] The template 8 has a shape substantially identical to the external shape 54 of the in situ coil 5 described previously. Preferably, the dimension of the template 8 is possibly larger, so as to provide a mounting margin between the external shape 54 of the in situ coil 5 and the shape of the template. The installation of the ex situ coil 7 around the in situ coil 5 is thus facilitated.

[0111] Alternatively, it is also possible to have a template 8 with the exact dimensions of the external shape 54 of the in situ coil 5, and to force-mount the ex situ coil 7 around the in situ coil 5.

[0112] Ideally, the template 8 used here is extensible, that is to say that it is adapted to have dimensions substantially identical (within the assembly margin) to the external shape 54 of the in situ coil 5 when it is extended, and dimensions smaller than the external shape 54 of the in situ coil 5 when it is retracted. Thus, the removal of the ex situ coil 7 obtained is made easier.

[0113] This template 8 takes for example the form of a mandrel made of metal, such as steel for example, which can move from a retracted position to an extended position. Here, the template extends and retracts along its longitudinal axis, as indicated by the double arrow illustrated in [Fig.5]. Alternatively, the template 8 extends and retracts perpendicular to its longitudinal axis, or even according to a combination of different axes in different directions.

[0114] The use of a template 8 that is at least partially pneumatic, that is to say, comprising at least one element whose volume varies by air injection is also conceivable, as well as any other suitable solution.

[0115] The ex situ winding E30, unlike the in situ winding E20, produces the ex situ coil 7 at a distance from its permanent location. The ex situ coil 7 is produced around the template 8, before being attached around the in situ coil 5 in a later step.

[0116] The ex situ winding E30 is carried out by suitable winding tooling, such as, for example, a needle winding machine, as previously for the in situ coil 5, or by a so-called “rotating spindle” winding machine (known in English as “spindle winding machine”). In the case of a rotating spindle winding machine, an electrically conductive wire unwinder is kept static, while the part around which the coil is produced is rotated. The part on which the coil is produced is in particular fixed to a spindle of the rotating spindle winding machine. This spindle is then rotated, which allows the rotation of the part which is integral with it. Here, the template 8, which therefore corresponds to the part on which the coil is produced, is fixed to the spindle, the latter however is not shown here.

[0117] Like the E20 in situ winding, the E30 ex situ winding is made of arranged wires (also known as orthocyclic winding).

[0118] Thus, the adapted winding tool winds the other wire segment electrically 3P conductor in a series of turns joined to each other around the template 8 in its extended form, for example in an upward movement, starting from a lower end of the template 8, to an upper end of the template 8 in order to form a first layer of the ex situ coil 7.

[0119] In particular, a height defined between the lower end and the upper end of the template 8 corresponds to a height between the main face of the yoke 10, at the bottom of the notch 200 and the edge 134 of the pair of lateral edges 104. Thus, the ex situ coil 7 produced remotely has a height similar to the in situ coil 5.

[0120] The ex situ winding E30 is continued by producing layers of turns superimposed on the first layer, so that the electrically conductive wires of each layer are placed in staggered rows with the electrically conductive wires of the layer that it covers at least partially.

[0121] The number of layers is preferably chosen in order to fill the space available within the notch 200. The number of layers of the ex situ coil 7 is however limited by the gap available between the two pairs of lateral edges 104 facing each other belonging to two neighboring teeth 100 and overhanging a given notch 200.

[0122] Thus, the number of turns per layer of the ex situ coil 7 is left to the discretion of those skilled in the art, to optimally fill the space available in the notch 200.

[0123] In this exemplary embodiment, two superimposed layers of electrically conductive wires 3 are placed around the extended template 8, in order to form the ex situ coil 7.

[0124] The ex situ coil 7 thus produced in the ex situ winding step E30 has an internal shape similar to the external shape 54 of the in situ coil 5. Indeed, the ex situ coil 7 takes on the silhouette of the template 8, the latter having been modeled on the external shape 54 of the in situ coil 5. Thus, advantageously, the ex situ coil 7 can be fitted over the in situ coil 5. This internal shape also has an internal dimension, geometrically describing the dimensions of the ex situ coil 7.

[0125] The step following the ex situ winding E30 consists of a report E40 of the ex situ coil 7 produced on the template 8.

[0126] It is thus necessary to carry out its reporting E40, that is to say its transfer from its place of production, that is to say the template 8 to its permanent location, that is to say, the tooth 100 more specifically, around the in situ coil 5.

[0127] For this, a tool adapted to the transfer of the ex situ coil 7 is used. This transfer tool 62 allows the ex situ coil 7 to be taken simultaneously by an inner end and an outer end.

[0128] The taking of the ex situ coil 7 by the transfer tool 62 is illustrated in [Fig.5] by two arrows.

[0129] This gripping of the ex situ coil 7 by its two inner and outer ends makes it possible on the one hand to hold the ex situ coil 7, and prevent it from deforming and / or unwinding, and on the other hand, facilitating the transfer around the tooth 100.

[0130] As a reminder, the cylinder head 10 has the shape of a disc pierced in its center. The internal end, oriented towards the central opening 14, constitutes a zone of small size for the passage of the transfer tool 62. Similarly, the external end is oriented towards the edge of the disc, also left free, and therefore favorable to the passage of the transfer tool 62.

[0131] Ideally, the transfer tool 62 is in contact with the ex situ coil 7 on its outer layer only, in order to facilitate the E40 reporting around the tooth 100. For example, this transfer tool 62 exerts a homogeneous pressure on each of the ends, in order to grip the ex situ coil 7 and dislodge it from the template 8 before transferring it to the tooth 100, around the in situ coil 5.

[0132] A mounting axis, parallel to the longitudinal axis A1 is then defined for each of the teeth 100 and passes through a barycenter of the core 102, this barycenter also corresponds to the barycenter of the in situ coil 5. The ex situ coil 7 is then fitted around the in situ coil 5 along this mounting axis. Thus, the ex situ coil 7 and the in situ coil are concentric around the mounting axis.

[0133] Alternatively, this transfer tool 62 corresponds for example to a pair of clamps gripping the coil ex situ 7, always at the internal and external ends. Other forms of suitable transfer tooling, automated or not, are obviously possible.

[0134] A side view of the reporting step E40 is shown in [Fig.7], where an ex situ coil 7 is reported on the tooth 100A.

[0135] In order to facilitate the E40 reporting, the template 8 passes into its retracted position during this step. Thus, the removal of the ex situ coil 7 from the template 8 on which it was produced is made easier.

[0136] It is also possible to carry out a clamping of the ex situ coil 7 upstream, or during its reporting E40, in order to ensure that the coil does not come undone during the transfer. Then, the turns of the ex situ coil 7 are held using at least one clamp tightened around the different layers of the coil.

[0137] By virtue of its production around a template 8 of carefully chosen shape, the ex situ coil 7 is made to fit around the in situ coil 5. The internal dimensions of the ex situ coil 7 are therefore similar to the external dimensions of the in situ coil 5, apart from the mounting margin. This mounting margin is also provided to ensure good fitting of one element onto the other.

[0138] Forced fitting of the ex situ coil 7 around the in situ coil 5 is also possible, using appropriate tools.

[0139] It is assumed here that a mounting margin of a few tenths of a millimeter to a few millimeters separates the in situ coil 5 from the ex situ coil 7 following the reporting step E40. Indeed, the internal dimension of the ex situ coil 7 is greater than the external dimension of the in situ coil 5, the difference between these two dimensions corresponding in particular to the planned mounting margin. In other words, a free space, of a dimension equal to the mounting margin, is left between the last layer of the in situ coil 7 and the first layer of the ex situ coil 7. For example, here, the mounting margin is equal to half a millimeter, which is added to the external dimension of the in situ coil 5.

[0140] Air therefore separates the in situ coil 5 from the ex situ coil 7. However, air is a thermal insulator, the two coils, in situ and ex situ, are therefore thermally insulated from each other. Heat dissipation is therefore degraded in the ex situ coil 7.

[0141] It is thus advantageous to place the in situ coil 5 in contact with the ex situ coil 7, by maximizing the contact surfaces between the outer layer 52 of the in situ coil 5 and an inner layer 72 of the ex situ coil 7. The outer layer 52 corresponds to the last layer of electrically conductive wire wound around the core 102, while the inner layer 72 corresponds to the first layer of electrically conductive wire of the ex situ coil 7. These layers are illustrated in [Fig.7].

[0142] In this way, since the in situ coil 5 is itself in contact with the core 102 of the tooth 100, a potential thermal evacuation surface is maximized.

[0143] For this, the method includes a step E51 of placing the attached coil in position, corresponding to the ex situ coil 7.

[0144] Using suitable tools, or with the hands, pressure is exerted on the internal side of the ex situ coil 7, in the direction of the external side, along the radial axis A2.

[0145] This tooling possibly corresponds to the transfer tooling described previously.

[0146] The ex situ coil 7, fitted around the in situ coil 5, is therefore pushed along the radial axis A2 by the appropriate tooling. This pressure is illustrated in particular in [Fig.6], using arrows describing the movement of the ex situ coil 7 relative to the in situ coil 5 assumed to be fixed around the tooth 100A.

[0147] This makes it possible to bring the inner layer 72 into contact with the outer layer 52 of the in situ coil 5.

[0148] Contact zones are therefore formed at the level of the internal face 122, and on the two lateral faces 142, while a residual play zone, corresponding to the entire remaining assembly clearance is located at the level of the external face 132, oriented towards the periphery of the cylinder head 10.

[0149] In other words, the ex situ coil 7 is displaced radially relative to the mounting axis, towards the periphery of the yoke, in order to bring it into contact with the in situ coil 5 on one side thereof, that is to say, at the level of the internal face 122. The residual mounting clearance is therefore left at the level of the radially opposite side relative to the mounting axis.

[0150] This residual play zone is formed between the in situ coil 5 and the ex situ coil 7.

[0151] Other geometries for contacting the in situ coil 5 and the ex situ coil 7 are also conceivable. However, given the substantially conical shape that the internal face 122 has once the internal coil head guide 42 is in place, the proposed embodiment, where the residual play zone is located at the level of the external face 132, makes it possible to minimize the residual play as much as possible.

[0152] The pressure exerted also places the electrical wires of the outer layer 52 of the in situ coil 5 and the electrical wires of the inner layer 72 of the ex situ coil in staggered rows, as illustrated in [Fig.7].

[0153] In other words, the electrical wires of the inner layer 72 of the ex situ coil 7 are inserted into the gaps left between the electrical wires of the outer layer 52 of the in situ coil 5.

[0154] This arrangement between the coils has the advantage of being compact and of maximizing the contact surfaces between the coil already in place and the attached coil.

[0155] In order to reduce the size of the residual clearance area, a forming step E52 is also provided.

[0156] Following the in situ winding E20, the first layer of electric wire of the in situ coil 5 rests on the curved surface of each of the coil head guides 42, 43, across the hollow 400.

[0157] Here, two hollows 400 are radially opposite relative to the mounting axis on each of the teeth 100, along the radial axis A2. In order to reduce the dimension of the residual clearance zone, in the forming step E52, it is provided to deform the in situ coil 5 and the ex situ coil 7 so that they match the shape of the hollow 400.

[0158] For this, a forming tool 64 is used. This is for example a press, a jack, or any other tool suitable according to the expertise of the person skilled in the art. In particular, a common tool can be used as the forming tool 64, as the transfer tool 62 mentioned above, and as the tool used to position the ex situ coil 7 in contact with the in situ coil 5.

[0159] The positioning of such a forming tool 64 is illustrated in [Fig.6].

[0160] The forming tool exerts pressure on the coil nesting on either side of the radial axis A2, at the level of the hollows 400.

[0161] Thus, the in situ coil 5 and the ex situ coil 7 are both simultaneously deformed so as to match the contours of the hollows 400.

[0162] Alternatively, in order to avoid exerting too much pressure on the crossing zone of the winding wires, each tooth 100 has a single coil head guide provided with a hollow 400, this coil head guide being placed opposite the starting point of the winding. Here, it would be the external coil head guide 43. In this case, pressure would be exerted from the single hollow 400, in the direction of the central opening 14, in order to conform the in situ coil 5 and the ex situ coil 7 in the hollow 400.

[0163] After the positioning step E51 and the forming step E52 of the coils, a residual clearance possibly remains in two zones, at the corners of the coil nesting, this nesting having a trapezoidal shape. The two residual clearance zones are located at two of the corners of this trapezoidal shape, along the long side of the trapezium.

[0164] The method continues with an electrical connection step E53.

[0165] For this, an electrical and mechanical connection of the in situ coil 5 with the ex situ coil 7 is made.

[0166] Indeed, here, the in situ coil 5 was produced on the tooth 100 with a first segment of electrically conductive wire 3, separate from the segment of electrically conductive wire 3P used during the production of the ex situ coil 7.

[0167] Thus, after reporting E40, the in situ coil 5 and the ex situ coil 7 are therefore not electrically connected.

[0168] In this first embodiment, the electrical connection step, in particular that between the in situ coil 5 and the ex situ coil 7, is carried out using the metallic and electrically conductive bar 430 overmolded in the external coil head guide 43. This bar 430 and its electrical connection to the tail 32 of the electrically conductive wire segment 3 of the in situ coil 5 has already been described previously.

[0169] The electrical connection of the two coils through the bar 430 is made by soldering, by laser soldering or by crimping, or any other electrical connection method left to the discretion of the person skilled in the art (with or without bar 430).

[0170] In a variant of this first embodiment, the electrical connection step E53 is carried out upstream, for example after the step E40 of attaching the ex situ coil 7 around the in situ coil 5, before proceeding with the forming E52 of the coils.

[0171] Thus, thanks to the method described, an assembled coil 9 is obtained, by producing a first coil around the tooth 100 by the in situ winding E20, followed by a second winding on the template 8 placed at a distance from the tooth 100. The ex situ coil 7 obtained is then reported, and fitted around the in situ coil 5. The two coils are then electrically connected, so that the electric current can flow there without discontinuity. The in situ coil 5 and the ex situ coil 7 are therefore similar to a single coil assembled 9 around the tooth 100, and source of a single magnetic field oriented along the longitudinal axis Al when supplied with electric current. Such a coil assembled 9 around the tooth 100B is shown in [Fig.7], via a sectional view.

[0172] The method also comprises an impregnation step E54. This step is carried out after forming the in situ coil 5 and the ex situ coil 7, ideally when the electrical connection of the coils has been made in order to obtain the assembled coil 9. This impregnation step E54 makes it possible to permanently fix the electrical wires forming the assembled coil 9 in a definitive position. In particular, the impregnation E54 eliminates any vibrations that could degrade the performance of the electrical machine in the long term, while increasing, among other things, the resistance to external forces, as well as the dissipation of the heat produced during the circulation of a current.

[0173] For this, an impregnation resin or varnish is for example deposited on the assembled coil 9, before being polymerized.

[0174] As a variant or in addition to the forming E52 of the coils, the insertion E52P of shims at the notches 200 is also possible to reduce the size of the residual play area. Shims, of suitable dimensions, are then inserted into a gap separating two neighboring assembled coils 9, in order to maintain the latter, and thus avoid any play and / or deformation.

[0175] These shims are for example made from an electrically insulating material.

[0176] The insertion E52P of the shims is followed by an impregnation step E54, in order to fix the assembly permanently, as described previously.

[0177] According to another variant, the forming step E52, and / or the insertion step E52P of the shims, as well as the impregnation step E54 described previously are replaced by a single filling step. Filling is usually known by the Anglo-Saxon term “potting”, sometimes also translated as “empotage” in French.

[0178] This step consists of filling with a material in liquid form, such as an epoxy, electrically insulating and thermally conductive, a space around the assembled coil 9, this space being defined using a mold. This material subsequently hardens, and allows the fixing of the assembled coil 9, in a manner similar to the impregnation E54.

[0179] According to a second embodiment, the two segments of electrically conductive wire 3, 3P used for the in situ winding E20 and for the ex situ winding E30 are electrically and mechanically bonded before and during the in situ winding E20. Ideally, a single electrically conductive wire 33, of suitable length, is used to carry out the in situ winding E20 and the ex situ winding E30.

[0180] The in situ winding step E20 is then carried out in the same way as previously described, using a needle winding machine 60. This machine unwinds the single electrically conductive wire 33 around the tooth 100 in order to constitute the in situ coil 5.

[0181] Once the desired number of layers and turns per layer is obtained, a length of electrically conductive wire 33 is left in surplus, before continuing the process directly with the ex situ winding E30. Just as in the first embodiment, this second winding is carried out on a template 8 at a distance from the tooth 100. Nevertheless, since the same electrically conductive wire is used, it is therefore the same needle winding machine 60 as for the in situ winding E20 which is used to carry out the ex situ winding E30.

[0182] The reporting step E40 of the ex situ coil 7 obtained remains the same as previously, with the folding of the template 8 in order to facilitate the transfer of the ex situ coil 7 to the in situ coil 5.

[0183] However, pads, not illustrated here, are placed in order to hook the excess electrically conductive wire, and thus maintain an adequate voltage between the in situ coil 5 and the ex situ coil 7.

[0184] These pads are located in particular on at least one of the coil head guides 42, 43, more precisely here on the external coil head guide 43. They are, for example, obtained by injection, at the same time as the rest of the part.

[0185] The other steps and variants proposed previously are also applicable to this second embodiment.

[0186] In the preceding description, the application of the method has been described for a tooth 100 of the cylinder head 10. The extension of the method to several teeth 100 is obvious to those skilled in the art.

[0187] Several combinations are possible for this extension. For example, it may be envisaged to carry out the in situ winding E20 and the ex situ winding E30 for a given tooth 100, before doing the same for another tooth 100. Alternatively, certain steps may be carried out in parallel with each other, depending on capacity requirements for example.

[0188] The present invention is in no way limited to the embodiments described and shown, but those skilled in the art will be able to provide any variant in accordance with the invention.

[0189] In particular, the method described is applicable to the installation of an electrically conductive wire around a tooth of the stator of an electric flux machine. axial, but its application also extends to the installation of an electrically conductive wire around a tooth of any type of axial flux electric machine, or even on wound rotors, whether axial or radial flux, in order to increase the filling rate of their slots. Note that the proposed method is particularly advantageous for winding a rotor and / or a stator on an axial flux electric machine. Indeed, in an axial flux electric machine, the dimension of the slots is smaller than in a radial flux electric machine.

[0190] Many possible alternatives for reducing the mounting clearance have been proposed in the description, whether by forming on suitable coil head guides, inserting shims, or potting. Other variants exist, such as, for example, producing an ex situ coil 7 with the exact dimensions of the external shape 54 of the in situ coil 5, the ex situ coil 7 would then be force-mounted on the in situ coil 5.

[0191] Similarly, alternatives not described are possible with regard to the production of the coils, whether in the choice of the section of the wire, for example, circular and of small diameter, or else of rectangular section, or in the winding geometry, which can be helical for example.

Claims

Claims

1. Winding method for placing an electrically conductive wire (3, 3P) around a core (102) of a tooth (100) of an electrical machine, said winding method being characterized in that it comprises the following steps: - in situ winding (E20) for winding a segment of said electrically conductive wire (3) around said core (102) in order to form an in situ coil (5), - ex situ winding (E30), consisting of winding another segment of said electrically conductive wire (3P) on a template (8), in order to form an ex situ coil (7) adapted to be fitted around said in situ coil (5), - a reporting (E40) of said ex situ coil (7) around said in situ coil (5) in order to form an assembled coil (9).

2. A winding method according to claim 1, wherein after the reporting (E40) of said ex situ coil (7) around said in situ coil (5), a forming (E52) of said ex situ coil (7) on said in situ coil (5) is provided.

3. Winding method according to claim 2, wherein at least one coil head guide (42, 43) is placed in contact with said tooth (100) before the in situ winding step (E20), said coil head guide (42, 43) being provided with at least one hollow (400), said ex situ coil (7) having an internal dimension greater than an external dimension of said in situ coil (5), the difference between the internal dimension of said ex situ coil (7) and the external dimension of said in situ coil (5) being equal to a mounting clearance, during said forming (E52), a portion of said in situ coil (5) is deformed in contact with at least a portion of said hollow (400), and said at least one ex situ coil (7) is deformed so as to be in contact with said portion of the in situ coil (5), in order to reduce said mounting clearance.

4. Winding method according to any one of claims 1 to 3, wherein, said ex situ coil (7) having an internal dimension greater than an external dimension of said in situ coil (5), the difference between the internal dimension of said ex situ coil (7) and the external dimension of said in situ coil (5) being equal to a mounting clearance, after having engaged the ex situ coil (7) around said in situ coil (5) along a mounting axis, a step of positioning (E51) consisting of moving said ex situ coil (7) radially relative to said mounting axis to bring said in situ coil (5) and said ex situ coil (7) into contact with each other on one side of the in situ coil (5) so as to leave said mounting clearance on a side radially opposite said side.

5. A winding method according to any one of claims 1 to 4, wherein said assembled coil (9) comprises superimposed layers of electrically conductive wires (3, 3P), said electrically conductive wires (3, 3P) of one layer are placed in staggered rows relative to the electrically conductive wires (3, 3P) of the layer below and / or above.

6. Winding method according to any one of claims 1 to 5, wherein, said electrically conductive wire segment (3P) of the ex situ winding (E30) being initially separated from said electrically conductive wire segment (3) of said in situ winding (E20), said electrically conductive wire segment (3) of said in situ winding (E20) and said electrically conductive wire segment (3P) of the ex situ winding (E30) are electrically connected after the reporting step (E40).

7. A winding method according to any one of claims 1 to 5, wherein said electrically conductive wire segment (3) of said in situ winding (E20) and said electrically conductive wire segment (3P) of said ex situ winding (E30) are electrically bonded before and during said in situ winding (E20).

8. Winding method according to any one of claims 1 to 7, wherein said template (8) having a variable size, after the ex situ winding step (E30), it is intended to reduce the size of the template (8).

9. Winding method according to any one of claims 1 to 8, in which, the electrical machine comprising two neighboring teeth (100) around which ex situ coils (7) are attached, after the step of attaching (E40) the ex situ coils (7), at least one coil wedge is inserted into a residual space located between said ex situ coils (7).

10. Electrical machine comprising at least one yoke (10) from which at least one tooth (100) rises around which an assembled coil (9) is wound, characterized in that said assembled coil (9) is produced according to a winding method according to one of claims 1 to 9.

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