Method and system for automatically winding a salient pole rotor body

Abstract

The invention relates to a method for winding (100) a rotor body comprising a central portion and a plurality of branches extending radially from the central portion, the winding method (100) using an automatic winding system comprising a needle suitable for winding a conductive wire around a branch along a winding path passing through a winding notch between a first point located at a first axial end of the branch and a second point located at a second axial end of the branch, the winding method (100) comprising steps of: - assigning (110) a target position to the second point, - determining (120) an axial deformation of the branch, - correcting (130) the target position based on the axial deformation, resulting in a corrected target position, and - moving (140) the needle from the first point to the second point corresponding to the corrected target position.

Description

[0001] Title of the invention: Method and system for automatic winding of a rotor body with salient poles

[0002] The present invention relates to the field of electrical engineering and more specifically concerns a method and a system for winding an electrical machine rotor, finding a particular application in the automotive field.

[0003] The electrical machines of electric or hybrid vehicles generally comprise a wound stator and a rotor whose magnetic poles comprise permanent magnets or a winding, the rotor being said to be wound in the latter case. Wound rotors are generally mainly made up of:

[0004] - a magnetic core made by an axial stack of magnetic steel sheets, cut to form radially and angularly distributed salient poles around a central body comprising a recess allowing a wound rotor rotation shaft to be inserted into the stack of sheets; and

[0005] - a winding formed of several coils of one or more conductive wires, in particular copper, each coil surrounding a salient pole of the magnetic core.

[0006] It is noted that in this application, an axial direction is parallel to the axis of rotation of the wound rotor, a radial direction is orthogonal to the axial direction while passing through the axis of rotation of the wound rotor, and the ortho-radial direction is orthogonal to the axial direction and to a radial direction. It is also understood that the electrical machines considered herein are radial flux electrical machines.

[0007] Each coil therefore comprises two portions extending axially along axial walls of the same salient pole, and two portions extending ortho-radially at the respective axial ends of the salient pole. The portions of the coil extending axially are each located between two salient poles, the space between two salient poles forming a winding notch. The opening of the latter must be sufficiently angularly extended to accommodate a needle allowing the winding of the salient poles.

[0008] The automatic winding of such a wound rotor in fact uses a needle through which the conductive wire to be wound passes. When winding a salient pole, the needle forms the winding of the conductive wire around the salient pole by passing axially between the salient pole and a first adjacent salient pole, then ortho-radially along a first axial end of the salient pole, then axially between the salient pole and a second adjacent salient pole, then ortho-radially along a second axial end of the salient pole, and so on.

[0009] To ensure that the conductive wire is held and placed in the winding slot, including during operation of the electrical machine when the conductive wire is subjected to centrifugal force, a high level of tension is applied to the conductive wire when it is wound around the salient pole.

[0010] This tension force is transmitted by contact to the salient pole formed by the stack of laminations. It is therefore a mainly axial compression force which is applied to the magnetic core of the rotor during winding. This compression force is all the more important as the number of turns wound around the salient pole increases.

[0011] It should be noted that in reality, to electrically insulate the conductive wire from the salient pole, an insulator is inserted between the conductive wire and the salient pole. This insulator often takes the form of insulating paper in the winding slots, and flanges made of synthetic polymer material (plastic) arranged at each axial end of the stack of sheets, these flanges being called coil head guides. The axial compression force therefore also applies to the coil head guides.

[0012] The inventors have found that different stacks of laminations constituting the magnetic cores of different wound rotors, due to their structure, exhibit elastic behaviors with very low stiffness coefficients, of the order of 50 kN / mm (kiloNewton per millimeter) in the elastic phase. When winding a salient pole in particular, the axial compression force applied by the conductive wire brings the axial ends of the salient pole together, in a way that is very difficult to model due to the parameters to be taken into account, these parameters being the material of the laminations, their roughness, their shape defects, the presence of dust, and their lamination assembly technology, using for example welding or gluing.

[0013] The inventors thus observed an axial reduction of a salient pole of a first stack of 6.33mm sheets by applying a compressive force of 22.3kN (Newton) to it, which corresponds to a stiffness coefficient of 3.529kN / mm, and an axial reduction of a salient pole of a second stack of 5.21mm sheets by applying a compressive force of 4.2kN to it, which corresponds to a stiffness coefficient of 0.81kN / mm.

[0014] When winding a wound rotor, the distance between the axial ends of the salient pole to be wound, and therefore between the two coil head guides on which the conductive wire is placed at the axial ends of the rotor, is therefore reduced and difficult to predict.

[0015] Currently, the trajectory of the needle relative to the salient pole that it winds is pre-programmed so that the conductive wire forms an orthocyclic stack of the sections of the conductive wire in a portion of the coil surrounding the salient pole, assuming that there is no axial compression of the salient pole during winding.

[0016] By "orthocyclic stack" is meant in this application, a stack maximizing the rate of filling with conductive wire, of the space intended for the conductive wire around a salient pole. Thus in an orthocyclic stack, when the conductive wire is of round section, a section of conductive wire of a winding layer is tangent to two sections of conductive wires of another winding layer, the centers of the three corresponding round sections forming an equilateral triangle.

[0017] Figure 1 shows in axial section at the level of a coil head guide 7, a coil 6 surrounding a salient pole formed by a magnetic core 9 of a wound rotor. The coil head guide 7 is arranged at an axial end of the salient pole and comprises a notch whose opening extends ortho-radially to receive the conductive wire of the coil 6. The conductive wire forming the coil 6 has in this notch of the coil head guide 7, an orthocyclic stack 60 of turns at the start of winding, then winding defects 62, 64 corresponding to layers of conductive wire not stacked in an orthocyclic manner.

[0018] These winding defects 62, 64 are due to the axial compression force F exerted by the tension of the conductive wire during winding, on the magnetic core 9 of the rotor and its coil head guide 7. Figure 1 shows that this axial compression force F has deviated the position of the coil head guide 7 relative to a plane N orthogonal to the axis of rotation 8 of the wound rotor. The axial end of the magnetic core 9 was delimited by this plane N, before the start of the winding of the salient pole. To avoid these winding defects, it is possible to take into account the behavior of the stack of rotor laminations during this axial compression in the preprogrammed trajectory, but this requires a long and expensive development time of the winding process for each structurally different rotor.

[0019] Pre-compression of the salient pole to be wound was considered to better control the placement of the wires during winding, the first turns having a tendency to relax otherwise as the winding of the salient pole progresses, but the inventors still frequently observe unwanted wire placements, causing wire crossings and non-orthocyclic stacking.

[0020] The present invention aims to remedy at least in part the aforementioned drawbacks by providing a method and a system for automatic winding of a rotor body, as well as a computer program, which make it possible to correct in real time the position of the needle during the winding of a salient pole of the rotor body, so as to take into account the axial compression exerted by the conductive wire wound by the needle.

[0021] To this end, the invention provides a method for winding a rotor body comprising a central portion and a plurality of branches extending radially from the central portion, the winding method using an automatic winding system comprising a needle capable of winding a conductive wire around one of the branches along a winding path comprising a passage in a winding notch between the branch and an adjacent branch, the passage extending from a first point located at a first axial end of the branch to a second point located at a second axial end of the branch, the winding method being characterized in that it comprises steps of:

[0022] - assignment of a target position to the second point,

[0023] - determination of axial deformation of the branch,

[0024] - correction of the target position based on the previously determined axial deformation, resulting in a corrected target position, and

[0025] - when the needle is located at the first point, movement of the needle from the first point to the second point corresponding to the corrected target position.

[0026] The winding process is implemented in particular by executing a computer program defining the winding path of the needle. This path comprises several points of passage of the needle, each associated with a position, a speed and possibly an acceleration of the needle. The points of passage located at the corners of a branch of the rotor body have a speed and an acceleration of zero. They are located on either side of the branch at the axial ends thereof, and their positions determine the correct placement of the conductive wire along an axial wall or an axial end of the branch.

[0027] In the invention, the target position assigned to the second point during the assignment step corresponds to a target position calculated or read by the computer program, and which would allow the conductive wire to form turns according to an orthocyclic stack in the winding slot when the needle moves from the first point to the second point having this target position, and when the branch of the rotor body is not axially deformed. This target position of the assignment step is therefore an initial target position which may be that of a preprogrammed path according to the hypothesis that there is no axial deformation, in a manner similar to the prior art.

[0028] The invention corrects this target position in real time, the corrected target position being the position finally retained for the second point.

[0029] Thanks to the invention, the placement of the conductive wire between the first point and the second point corresponds to an orthocyclic stacking of turns of the conductive wire in the winding notch, since the second point takes into account the axial deformation exerted on the branch during the winding thereof.

[0030] The different branches can be wound one after the other or at the same time depending on whether one conductive wire is used per branch or just one for all the branches.

[0031] The invention applies to a wound rotor of a radial flux electric machine, the wound rotor having salient poles, but is not limited to automotive applications.

[0032] The rotor body designates a magnetic core of a wound rotor, formed for example from a stack of laminations, and possibly equipped with coil head guides. Each axial end of the rotor body is possibly equipped with one or more coil head guides depending on whether such a guide forms a star-shaped part covering the axial ends of each salient pole formed by the magnetic core, or forms an insulator of only part of the salient poles.

[0033] The branches of the rotor body therefore each comprise a portion of the magnetic core forming a salient pole, and possibly portions of two coil head guides or two coil head guides depending on the construction of these guides at the axial ends of the rotor body. The branches of the rotor body with their respective coils form magnetic poles of the wound rotor.

[0034] The salient poles may have different shapes, including within the same rotor. The salient poles each have at least one substantially parallelepipedal portion receiving a coil of conductive wire. This portion is optionally extended to an outer radial periphery of the salient pole, by a pole head comprising ortho-radial extensions holding the coil in position despite the centrifugal force when the rotor is in operation.

[0035] Furthermore, the conductive wire preferably has a round section, but other sections can be considered, for example square or rectangular sections. Finally, the magnetic core is not necessarily made by stacking sheets, the invention applying to any magnetic core that can be axially deformed during its winding.

[0036] In one embodiment of the invention, the branch extending radially from the central part to an external radial end of the branch, the step of determining an axial deformation comprises obtaining a value representative of a distance in an axial direction, between a reference point of the central part, and a point of the external radial end of the branch at its second axial end.

[0037] The axial compression of the branch during its winding deflects the position of the axial end of the branch relative to a plane orthogonal to the axis of rotation of the wound rotor, as shown in Figure 1. By measuring or calculating the distance between, on the one hand, the point of the central part of the rotor body, this central part being able to be impacted by the axial compression but without deviating relative to the orthogonal plane, and on the other hand the external radial end point of the branch, this deviation can be quantified. The point of the central part is preferably located on the axial end of the rotor body comprising the second axial end of the branch. Obtaining this distance uses, for example, a distance sensor, the position of which is fixed relative to the central part.

[0038] The branch being formed at least in part by a magnetic core delimited at the second axial end of the branch, and in an axial plane passing through an axis of rotation of the rotor body, by a first straight line forming a deflection angle with a second straight line orthogonal to the axis of rotation of the rotor body in the axial plane, the correction step calculates for example the coordinates of an image of the target position by a rotation of center the intersection between the first and second straight lines and angle the deflection angle.

[0039] In this embodiment of the invention, the deflection angle corresponding to a rotation of the second axial end of the branch relative to the central part of the rotor body, the target position of the needle is corrected by performing this same rotation on the target position. The deflection angle is for example deduced from the distance between on the one hand the reference point of the central part and on the other hand the external radial end point of the branch, and from the dimensions of the magnetic core. The second straight line, orthogonal to the axis of rotation of the rotor, delimits for example the axial end of the central part of the magnetic core. This axial end of the central part of the magnetic core is extended by the second axial end of the branch.

[0040] Furthermore, since the path comprises several first points and several second points to form a number of turns corresponding to different radial positions on the branch, and to different winding layers, the winding method preferably comprises as many steps of assigning a target position, determining an axial deformation, correcting and moving as the number of turns. The steps of the winding method are, for example, repeated for each turn formed by the needle around the branch, or only when forming certain turns. In particular, the positioning of the first turns generally does not require correction of the position of the needle.

[0041] Similarly, it is preferable to symmetrically correct the position of the needle when it positions the conductive wire in the other winding notch of the branch. More specifically, the path comprising for each turn to be formed, a first passage of the needle from the first point to the second point, a second passage of the needle in an ortho-radial direction from the second point to a third point located at the second axial end of the branch and facing a winding notch opposite the winding notch with respect to the branch, a third passage of the needle from the third point to a fourth point located at the first axial end of the branch and facing the opposite winding notch, and a fourth passage in the ortho-radial direction from the fourth point to the first point, the winding method comprises a further step of assigning a target position for the fourth point,another step of correcting the target position for the fourth point based on another step of determining an axial deformation of the branch, resulting in a corrected target position for the fourth point, and another step of moving the needle from the third point to the fourth point corresponding to the corrected target position for the fourth point, when the needle is located at the third point.,

[0042] Of course, the positions of the third point and the first point are corrected according to the corrections applied respectively to the second point and the fourth point, but these corrections do not require the determination of a deformation of the magnetic core at the level of the branch. Indeed, the ortho-radial dimension of a branch is much less extensive than its axial dimension, which limits the deformation of the branch in the ortho-radial direction.

[0043] Furthermore, according to an optional characteristic of the winding method according to the invention, it comprises a prior step of axial compression of the branch.

[0044] This preliminary step ensures good tension of the conductive wire and that it is held securely around the branch, once it has been wound.

[0045] The invention also relates to an automatic winding system for a rotor body comprising a central part and several branches extending radially from the central part, the automatic winding system comprising a needle capable of winding a conductive wire around one of the branches along a winding path comprising a passage in a winding notch between the branch and an adjacent branch, the passage extending from a first point located at a first axial end of the branch to a second point located at a second axial end of the branch, the automatic winding system being characterized in that it comprises:

[0046] - means of assigning a target position to the second point,

[0047] - means of determining axial deformation of the branch,

[0048] - means for correcting the target position as a function of an axial deformation resulting from the means for determining an axial deformation, the correction means being capable of providing a corrected target position, and

[0049] - means for moving the needle from the first point to the second point corresponding to the corrected target position.

[0050] The automatic winding system according to the invention therefore comprises means for implementing the winding method according to the invention. According to one embodiment of the automatic winding system according to the invention, the branch extending radially from the central part to an external radial end of the branch, the means for determining an axial deformation comprise a distance sensor capable of making it possible to obtain a value representative of a distance in an axial direction, between a reference point of the central part, and a point of the external radial end of the branch at its second axial end.

[0051] The branch being formed at least in part by a magnetic core delimited at the second axial end of the branch, and in an axial plane passing through an axis of rotation of the rotor body, by a first straight line forming a deviation angle with a second straight line orthogonal to the axis of rotation of the rotor body in the axial plane, the correction means are for example capable of calculating the coordinates of an image of the target position by a rotation of center the intersection between the first and second straight lines and angle the deviation angle.

[0052] The invention also relates to a computer program comprising program code instructions for executing the steps of the winding method according to the invention, when said program is executed on one or more processors.

[0053] The automatic winding system according to the invention and the computer program according to the invention have advantages similar to those of the winding method according to the invention.

[0054] Other characteristics and advantages of the invention will become apparent from the following description on the one hand, and from several examples of embodiment given for informational and non-limiting purposes with reference to the attached schematic drawings on the other hand, in which:

[0055] [fig 1] already commented on in relation to the prior art, represents in axial section a coil in a coil head guide fixed to an axial end of a magnetic core forming a salient pole of a wound rotor, only an axial end portion of the salient pole being represented,

[0056] [fig 2] represents in perspective a rotor body intended to be wound according to a winding method according to the invention, in one embodiment of the invention,

[0057] [fig 3] represents the rotor body of figure 2 in axial section, at the start of winding by an automatic winding system according to the invention, in one embodiment of the invention, a rotation shaft being inserted into the rotor body, and a compression device being placed at the ends of a branch of the rotor body,

[0058] [fig 4] represents the winding of a branch of the rotor body of figure 2 at the start of winding, this winding not requiring correction of a winding needle according to the invention, the branch being represented in an axial plane, on the one hand by one of its axial end portions, and on the other hand seen from the side in its entire axial length,

[0059] [fig 5] represents the winding of the branch of the rotor body of figure 2 at the end of winding, this winding not requiring correction of a winding needle according to the invention, the branch being represented in an axial plane, on the one hand by one of its axial end portions, and on the other hand seen from the side in its entire axial length,

[0060] [fig 6] represents steps of the winding method according to the invention, according to the embodiment mentioned in relation to figure 2, and

[0061] [fig 7] represents the winding of the branch of the rotor body of figure 2 at the end of winding, this winding being carried out according to the winding method according to the invention mentioned in relation to figure 2, the branch being represented in an axial plane, by one of its axial end portions only.

[0062] In one embodiment of the invention, a winding method 100 according to the invention (referenced figure 6) is used to wind a rotor body 1 shown in figure 2, with a conductive wire 3 (shown figure 3), here a copper wire of round section, and obtain a wound rotor. Other types of conductive wire can of course be used.

[0063] As shown in Figure 2, the rotor body 1 comprises a magnetic core 11 formed from an axial stack of magnetic laminations, the axial direction represented by an axis x being parallel to an axis of rotation R of the wound rotor. The magnetic core 11 comprises a cylindrical central portion 112 comprising a recess 14 for the passage of a rotation shaft 15 (referenced Figure 3), and salient poles 114 extending radially from the cylindrical central portion 112.

[0064] The rotor body 1 also comprises coil head guides 16 arranged at each axial end of the magnetic core 11. These coil head guides 16 are made of electrically insulating material and have a star shape. Each coil head guide 16 in fact comprises a central portion 162 and a recess which are superimposed respectively on the cylindrical central portion 112 of the magnetic core 11 and on the recess 14, as well as arms 165 each extending from the central portion 162 to an external radial end 164 of the arm 165.

[0065] The arms 165 of the coil head guides 16 are superimposed one by one on the salient poles 114 of the magnetic core 11, on either side of the latter, to form branches 12 of the rotor body 1, intended to be wound. The spaces between the branches 12 form winding notches, such as the winding notches referenced 12_1 and 12_2 in FIG. 2.

[0066] In this embodiment of the invention, the branches 12 of the rotor body end radially with ortho-radial extensions capable of confining the winding between a central part 10 (referenced figure 3) of the rotor body 1 and these ortho-radial extensions, which form on either side of each branch 12, winding cavities. The central part 10 of the rotor body 1 corresponds to the cylindrical central part 112 of the magnetic core 11 completed by the central portions 162 of each head guide of the coils 16.

[0067] A winding notch therefore comprises a first winding cavity intended to receive conductive wire 3 surrounding one of the branches 12 delimiting the winding notch, a second winding cavity intended to receive conductive wire 3 surrounding the other of the branches 12 delimiting the winding notch, and a space between the ortho-radial extensions of the branches 12 and between the first and second winding cavities, allowing the passage of a needle 2 (referenced figure 3) to form windings of conductive wire 3 around each branch 12.

[0068] It is also visible in Figures 2 and 3 that the arms 165 of each coil head guide 16 each form a winding notch 160 arranged ortho-radially, this winding notch 160 being delimited radially on the one hand by the central portion 162 of the coil head guide 16 and on the other hand by the external radial end 164 of the arm 165. The bottom of the winding notch 160 of the arm 165 is less axially extended than the external radial end 164 of the arm 165 and than the central portion 162 of the coil head guide. The edges between, on the one hand, the bottom of the winding notch 160 of the arm 165 and, on the other hand, the bottoms of the winding cavities formed by the ortho-radial extensions of the branch 12, here have a rounded shape and grooves 18 for positioning the conductive wire 3, which makes it easier to position the conductive wire 3 correctly by the needle 2.The path of the needle 2 around a branch 12 of the rotor body 1 to form a turn around it is represented by dotted lines in Figure 2.

[0069] A first part tl of the path extends axially in the winding notch 12_1 from a first point pl located at a first axial end 13 of the branch 12, to a second point p2 located at a second axial end 17 of the branch 12. The first and second points pl and p2 are located opposite the winding notch 12_1.

[0070] A second part t2 of the path extends ortho-radially on an arm 165 of a coil head guide 16 located at the second axial end 17 of the branch 12, from the second point p2 to a third point p3 located at the second axial end 17 of the branch 12 opposite the winding notch 12_2.

[0071] A third part t3 of the path extends axially in the winding notch 12_2 from the third point p3 to a fourth point p4 located at the first axial end 13 of the branch 12, opposite the winding notch 12_2.

[0072] Finally, a fourth part t4 of the path extends ortho-radially on an arm 165 of a coil head guide 16 located at the first axial end 13 of the branch 12, from the fourth point p4 to the first point pl.

[0073] Points pl to p4 are extreme points of the path taken by needle 2 and correspond to a zero speed and acceleration of needle 2. The path of needle 2 is also defined by other intermediate points of non-zero speed and / or acceleration. All the points of the path are determined by a computer program whose execution allows the movement of needle 2, computer 4 (referenced figure 3) executing this program being connected electronically to a robotic arm not shown, capable of moving needle 2 along the path determined by the computer program.

[0074] In this embodiment of the invention, the needle 2 moves axially to place the conductive wire 3 between the points p1 and p2 on the one hand and between the points p3 and p4 on the other hand, the rotor body 1 being kept fixed. On the other hand, to place the conductive wire 3 ortho-radially between the points p2 and p3 on the one hand and between the points p4 and p1 on the other hand, the rotor is rotated and the needle 2 moves only to compensate for the circular movement of the rotor by a movement allowing the conductive wire 3 to be placed in a rectilinear manner. Alternatively, the rotor remains fixed throughout the needle's path, or the rotor moves to place the conductive wire 3 axially along the branches of the rotor body while the needle remains fixed.

[0075] Points pl to p4 are of course redefined for each new turn that needle 2 forms around branch 12. The determination of points pl to p4 will be explained in more detail in relation to figures 4 to 7.

[0076] Figure 3 now illustrates an automatic winding system 40 according to the invention, in this embodiment of the invention, in position for winding the rotor body 1. The automatic winding system 40 comprises the computer 4, the robotic arm (not shown) and the needle 2 fixed to this robotic arm. In this embodiment of the invention, the automatic winding system 40 further comprises a compression device 5 placed on a branch 12 to be wound.

[0077] This compression device 5 comprises a first clamping jaw 52 arranged against the first axial end 13 of the branch 12, and a second clamping jaw 54 arranged against the second axial end 17 of the branch 12. These two clamping jaws are partly inserted into a guide 53 allowing them to slide in translation against each other, a screw 56 allowing this movement. The screw 56 is inserted partly into a threaded orifice of the first jaw 52 and partly into a screw passage of the second jaw 54, this passage comprising a stop capable of blocking the head of the screw 56 by means of a spring 58.

[0078] The compression device 5 is used to compress the branch 12 before it is wound in order to limit the axial deformation of the branch 12 during winding and thus promote good positioning of the conductive wire 3. The spring 58 makes it possible to keep the jaws 52, 54 clamped against the branch 12 even when the conductive wire 3 adds axial compression to that already applied by the compression device 5 to the branch 12.

[0079] We will now describe in relation to Figures 4 and 5, an axial movement of the needle 2 from the first point p1 to the second point p2, generated by the automatic winding system 40, when the branch 12 being wound is not axially deformed. In this case the automatic winding system 40 does not implement the winding method 100 according to the invention, which assumes that an axial deformation of the branch 12 exists. However, these Figures 4 and 5 allow a good understanding of the steps of the winding method 100 according to the invention when such a deformation exists. Figure 4 shows the axial displacement of the needle 2 just before it reaches the second point p2, at the start of the winding of the branch 12, in an axial plane P passing through the axis of rotation R of the rotor body 1 and through the second point p2. This displacement is symbolized by the solid arrow in Figure 4.The position of the needle 2 is, in this embodiment of the invention, defined by the position of a point A located on the needle 2. The position of the second point p2 is therefore here that of the point A of the needle 2, when the latter places the conductive wire 3 on a first winding layer, and at a first radial position on the branch 12. The first winding layer is that which is in contact with the rotor body 1 and the first radial position on the branch 12 corresponds to the position of the conductive wire 3 closest to the central part 10 of the rotor body 1. The second point p2 is more precisely defined by the radial position zA of the point A on a z axis of radial direction, and by the axial position xA of the point A on the x axis.

[0080] The partial axial view in this figure 4 shows how the conductive wire 3 will then be positioned in the winding notch 160 of the coil head guide 16 located at the second axial end 17. The conductive wire 3 is shown there sectioned in the winding notch 160 to better visualize the position of the conductive wire 3 in the axial plane P.

[0081] Figure 5 shows the axial displacement of the needle 2 just before it reaches the second point p2, while the branch 12 is already almost entirely wound, in the axial plane P passing through the axis of the rotor body 1 and through the second point p2. In this configuration, the position of the second point p2 is that of point A of the needle 2, when the latter places the conductive wire 3 on a fourth layer of winding, and at a radial position on the branch 12 closer to the outer radial end 164 of the arm 165, than to the central part 10 of the rotor body 1. The radial position zA and the axial position xA of the second point p2 therefore vary depending on the turn being formed.

[0082] In these two figures 4 and 5, the magnetic core 11 of the rotor body 1 not undergoing axial deformation, the radial positions zA and axial xA of the second points p2 of each turn of conductive wire 3 are for example read in a table giving these values ​​for a given type of rotor body. It is noted, in the partial axial view of figure 5, that the stacking of the turns is orthocyclic although no correction of the positions of the second points p2 has been carried out. We now describe in relation to figures 6 and 7, the winding method 100 according to the invention when the magnetic core 11 undergoes axial deformation during the winding of the rotor body 1. The winding method 100 is implemented by the automatic winding system 40.

[0083] A first step 105 of the winding method 100 is the prior compression of a branch 12 of the rotor body 1, by the compression device 5. The compression device 5 exerts for example an axial compression force of 10 kN between the axial ends 13, 17 of the branch 12. In an alternative embodiment, this step 105 of compression prior to winding does not take place.

[0084] A second step 110 of the winding method 100 is the assignment of a target position to the second point p2, that is to say the axial position xA and the radial position zA as assigned to the second point p2 in a similar manner to FIGS. 4 and 5 following the turn of conductive wire 3 being formed. Indeed, this target position (xA, zA) corresponds to a position initially assigned to the second point p2 assuming that the branch 12 is not axially deformed.

[0085] This target position (xA, zA) is read from a table comprising the target positions of point A, for each turn of conductive wire 3 on each winding layer of branch 12. This table is recorded in a memory of computer 4, and its values ​​are predetermined for the type of rotor body corresponding to rotor body 1. Alternatively, the target positions of the second point p2 are calculated by computer 4 as a function of the type of rotor body corresponding to rotor body 1.

[0086] A third step 120 of the winding method 100 is the determination of an axial deformation of the branch 12. Of course, in this third step 120, even when this is not specified, reference is only made to the second axial end 17 of the branch 12 and to the axial end of the central part of the rotor body 1, extending this second axial end 17 of the branch 12. In other words, reference is not made to the elements located at or near the first axial end 13 of the rotor body 1. In addition, the axial plane P comprising the second point p2 and passing through the axis of rotation R of the rotor body 1 is considered. It should be noted that in the partial axial view of FIG. 7, as in those of FIGS. 4 and 5, the conductive wire 3 is shown sectioned in the winding notch 160 to better visualize the position of the conductive wire 3 in the axial plane P.In this third determination step 120, the automatic winding system 40 uses a distance sensor 50, shown in FIG. 7, and making it possible to measure or calculate a distance 6 in the axial direction, between on the one hand a reference point 1620 located on the central portion 162 of the coil head guide 16, and on the other hand a point 1640 located on the external radial end 164 of the arm 165, these two points being located at the second axial end 17 of the branch 12. This distance 6 is here measured in the axial plane P passing through the axis of rotation R of the rotor body 1 and the second point p2, but could alternatively be measured in any other axial plane.

[0087] The reference point 1620 on the central portion 162 and the point 1640 on the external radial end 164 being located at the same axial level when the branch 12 is not axially deformed, the distance 6 obtained during this third determination step 120 makes it possible to quantify the deviation of the branch 12 relative to a plane orthogonal to the axis of rotation R of the rotor body 1.

[0088] In this third determination step 120, a point of the external radial end 164 of the branch 12 and a reference point of the central portion 162 are therefore preferably chosen which are located at the same axial level when the branch 12 is not axially deformed. In an alternative embodiment of the invention in which this is not possible, the axial distance existing between these points before axially compressing the branch 12 is subtracted or added to the distance 6 obtained during this third determination step 120, so as to obtain a distance representative of the deviation of the branch 12 relative to a plane orthogonal to the axis of rotation R of the rotor body 1.

[0089] In this third determination step 120, a deflection angle a of the branch 12 is then calculated with respect to a plane orthogonal to the axis of rotation R of the rotor body 1. This deflection angle a is calculated knowing the radial dimension (■ of the branch 12. The coil head guide 16 strictly matches the radial dimensions of the magnetic core 11, this radial dimension (■ here corresponds to the distance, measured in the radial direction z, between the radial end of the salient pole 114 of the branch 12 and the cylindrical central portion 112 of the magnetic core 11, this distance also being the distance measured in the radial direction z, between the external radial end 164 of the arm 165 and the central portion 162 of the coil head guide 16. We therefore have: tan (a) = 6 / 1

[0090] This deflection angle a corresponds in the axial view of Figure 7, that is to say in the axial plane P, to the angle between on the one hand a first straight line d1 which follows in a radial direction, the shape of the axial end of the salient pole 114, this axial end of the salient pole 114 being planar, and on the other hand a second straight line d2 orthogonal to the axis of rotation of the rotor body 1 and which follows in a radial direction, the shape of the axial end of the cylindrical central part 112 of the magnetic core 11, this axial end of the cylindrical central part 112 also being planar. These two straight lines intersect at a point of intersection O.

[0091] Of course, the axial end of the salient pole 114 can deform in a non-linear manner and not be flat. In this case, this deformation is approximated so as to obtain a deviation angle representative of this deformation and formed between two straight lines intersecting at the point of intersection O, this point of intersection O corresponding to the junction in the axial plane P, between the axial end of the cylindrical central part 112 of the magnetic core 11 and the axial end of the salient pole 114.

[0092] A fourth step 130 of the winding method 100 is the correction of the target position (zA, xA) assigned to the second point p2 in the second assignment step 110, resulting in a corrected target position (x'A, z'A) which is finally assigned to the second point p2. This corrected target position (x'A, z'A) is obtained by a rotation of the point A in the axial plane P passing through this point A and through the rotation axis R, of angle the angle of deviation a calculated previously, and of center the point of intersection O between the first line dl and the second line d2. We therefore have: z'A = sin (a) * xA + cos (a) * zA and x'A = cos (a) * xA - sin (a) * zA, * being the multiplication operator.

[0093] A fifth step 140 of the winding method 100 is then, when the needle 2 is located at the first point pl, the displacement of the needle 2 from the first point pl to the second point p2 corresponding to the corrected target position (x'A, z'A). This displacement is carried out so as to apply a significant tension on the conductive wire 3, of the order of 20 to 50N (Newton). Then a sixth step 150 of the winding method 100 is the placement of the conductive wire 3 ortho-radially up to the third point p3, the latter being corrected, with respect to its position initially assigned in the memory of the computer 4, by the same axial and radial offset as the second point p2. This placement is also carried out by applying a significant tension on the conductive wire 3.

[0094] The winding method 100 then repeats the second to fifth steps of the winding method by adapting them to the fourth point p4, places the conductive wire 3 ortho-radially up to the first point pl in a similar manner to the sixth step, then repeats the second to sixth steps of the winding method as previously described, and so on.

[0095] In this embodiment of the invention, given that the correction of the placement of the needle 2 is carried out both on the first part t1 of its path and on the third part t3 of its path t3, the automatic winding system 40 comprises a distance sensor 50 at each end of the rotor body 1, preferably fixed relative to the central part 10 of the rotor body 1. These distance sensors are for example very precise distance sensors, to within 10 microns. The measured distance 6 can in fact be of the order of 0.5 mm for a compression force of 20 kN, the deformation angle being in this case of the order of two degrees.

[0096] The computer 4 comprises at least one processor, a random access memory, a read-only memory storing the computer program, and means of communication with the robotic arm. Thus, the computer program, when executed on the processor, is capable of implementing the second to sixth steps of the winding method 100. The first step 105 can also be controlled by the computer 4 if the latter comprises means for actuating the compression device 5.

[0097] Of course, the invention is not limited to the examples which have just been described and numerous adjustments can be made to these examples without departing from the scope of the invention.

Claims

CLAIMS 1- A method of winding (100) a rotor body (1) comprising a central portion (10) and a plurality of branches (12) extending radially from the central portion (10), the winding method (100) using an automatic winding system (40) comprising a needle (2) capable of winding a conductive wire (3) around one of the branches (12) along a winding path comprising a passage in a winding notch (12_1) between the branch (12) and an adjacent branch, the passage extending from a first point (pl) located at a first axial end (13) of the branch (12) to a second point (p2) located at a second axial end (17) of the branch (12), the winding method (100) being characterized in that it comprises steps of: - assignment (110) of a target position (xA, zA) to the second point (p2), - determination (120) of an axial deformation of the branch (12), - correction (130) of the target position (xA, zA) as a function of the previously determined axial deformation, resulting in a corrected target position (x'A, z'A), and - when the needle (2) is located at the first point (pl), movement (140) of the needle (2) from the first point (pl) to the second point (p2) corresponding to the corrected target position (x'A, z'A). 2- Method for winding (100) a rotor body (1) according to claim 1, in which the branch (12) extending radially from the central part (10) to an external radial end of the branch (12), the step of determining (120) an axial deformation comprises obtaining a value representative of a distance (6) in an axial direction (x), between a reference point (1620) of the central part (10), and a point (1640) of the external radial end of the branch (12) at its second axial end (17). 3- Method of winding (100) a rotor body (1) according to claim 1 or 2, in which the branch (12) is formed at least in part by a magnetic core (11) delimited at the second axial end (17) of the branch (12), and in an axial plane passing through an axis of rotation (X) of the rotor body (1), by a first straight line (dl) forming a deflection angle (a) with a second straight line (d2) orthogonal to the axis of rotation (X) of the rotor body (1) in the axial plane, the correction step (130) calculates the coordinates of an image of the target position (xA, zA) by a rotation of center the intersection (O) between the first and second straight lines (dl, d2) and angle the deflection angle (a). 4- Method for winding (100) a rotor body (1) according to any one of claims 1 to 3, in which the path comprising several first points (pl) and several second points (p2) to form a number of turns corresponding to different radial positions on the branch (12), and to different winding layers, the winding method (100) comprises as many steps of assigning (110) a target position (xA, zA), determining (120) an axial deformation, correcting (130) and moving (140) as the number of turns. 5- Method for winding (100) a rotor body (1) according to any one of claims 1 to 4, wherein the path comprising for each turn to be formed, a first passage of the needle (2) from the first point (pl) to the second point (p2), a second passage of the needle (2) in an ortho-radial direction from the second point (p2) to a third point (p3) located at the second axial end (17) of the branch (12) and opposite a winding notch (12_2) opposite the winding notch (12_1) relative to the branch (12), a third passage of the needle (2) from the third point (p3) to a fourth point (p4) located at the first axial end (13) of the branch (12) and opposite the opposite winding notch (12_2), and a fourth passage in the ortho-radial direction from the fourth point (p4) to the first point (pl), the winding method (100) comprises a further step of assigning (110) a target position (xA, zA) for the fourth point (p4),another step of correcting (130) the target position (xA, zA) for the fourth point (p4) based on another step of determining (120) an axial deformation of the branch (12), resulting in a corrected target position (x'A, z'A) for the fourth point (p4), and another step of moving (140) the needle (2) from the third point (p3) to the fourth point (p4) corresponding to the corrected target position (x'A, z'A) for the fourth point (p4), when the needle (2) is located at the third point (p3)., 6- Method of winding (100) a rotor body (1) according to any one of claims 1 to 5, comprising a prior step of axial compression (105) of the branch (12). 7- Automatic winding system (40) of a rotor body (1) comprising a central part (10) and several branches (12) extending radially from the central part (10), the automatic winding system (40) comprising a needle (2) capable of winding a conductive wire (3) around one of the branches (12) along a winding path comprising a passage in a winding notch (12_1) between the branch (12) and an adjacent branch, the passage extending from a first point (pi) located at a first axial end (13) of the branch (12) to a second point (p2) located at a second axial end (17) of the branch (12), the automatic winding system (40) being characterized in that it comprises: - means for assigning a target position (xA, zA) to the second point (p2), - means for determining an axial deformation of the branch (12), - means for correcting the target position (xA, zA) as a function of an axial deformation resulting from the means for determining an axial deformation, the correction means being capable of providing a corrected target position (x'A, z'A), and - means for moving the needle from the first point (pl) to the second point (p2) corresponding to the corrected target position (x'A, z'A). 8- Automatic winding system (40) of a rotor body (1) according to claim 7, wherein the branch (12) extending radially from the central part (10) to an external radial end of the branch (12), the means for determining an axial deformation comprise a distance sensor (50) capable of allowing the obtaining of a value representative of a distance (6) in an axial direction (x), between a reference point (1620) of the central part (10), and a point (1640) of the external radial end of the branch (12) at its second axial end (17). 9- Automatic winding system (40) of a rotor body (1) according to claim 7 or 8, wherein the branch (12) being formed at least in part by a magnetic core (11) delimited at the second axial end (17) of the branch, and in an axial plane passing through an axis of rotation (X) of the rotor body (1), by a first straight line (dl) forming a deflection angle (a) with a second straight line (d2) orthogonal to the axis of rotation (X) of the rotor body (1) in the axial plane, the correction means are capable of calculating the coordinates of an image of the target position (xA, zA) by a rotation of center the intersection (O) between the first and second straight lines (dl, d2) and angle the deflection angle (a). 10- Computer program comprising program code instructions for executing the steps of the winding method (100) according to any one of claims 1 to 6, when said program is executed on one or more processors.

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