Method and system for the automatic winding of a salient-pole rotor body

Abstract

Method and system for automatic winding of a salient-pole rotor body. The invention relates to a method for winding (100) a rotor body comprising a central part and several arms extending radially from the central part. The winding method (100) uses an automatic winding system comprising a needle adapted to wind a conductive wire around an arm along a winding path passing through a winding slot between a first point located at a first axial end of the arm and a second point located at a second axial end of the arm. The winding method (100) comprises the steps of: - assigning (110) a target position to the second point, - determining (120) an axial deformation of the arm, - correcting (130) the target position as a function of the axial deformation, resulting in a corrected target position.and- displacement (140) of the needle from the first point to the second point corresponding to the corrected target position. (Figure 6),

Description

Title of the invention: Method and system for the automatic winding of a salient-pole rotor body

[0001] The present invention relates to the field of electrical engineering and more specifically concerns a method and a winding system for an electric machine rotor, finding a particular application in the automotive field.

[0002] The electrical machines of electric or hybrid vehicles generally comprise a wound stator and a rotor whose magnetic poles consist of permanent magnets or a winding, the rotor being said to be wound in the latter case. Wound rotors are generally mainly composed of:

[0003] - of a magnetic core made by an axial stacking of steel sheets magnetic, cut to form radially and angularly distributed salient poles around a central body with a recess allowing the insertion, into the stack of laminations, of a shaft for rotating the wound rotor; and

[0004] - of a winding formed of several coils of one or more conductive wires, particularly in copper, each coil surrounding a salient pole of the magnetic core.

[0005] It should be 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 both the axial and radial directions. It is also understood that the electrical machines considered here are radial flux electrical machines.

[0006] Each coil therefore comprises two portions extending axially along the axial walls of the same salient pole, and two portions extending orthoradially to the respective axial extremities of the salient pole. The axially extending portions of the coil are each located between two salient poles, the space between two salient poles forming a winding slot. The opening of this slot must be sufficiently large angularly to accommodate a needle for winding the salient poles.

[0007] The automatic winding of such a wound rotor 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.

[0008] To ensure the retention of the conductor wire and its placement in the winding slot, including during the operation of the electrical machine during which the conductor wire is subjected to a centrifugal force, a significant level of tension is applied to the conductor wire during its winding around the salient pole.

[0009] This tensile force is transmitted by contact to the salient pole formed by the stack of laminations. It is therefore a primarily axial compressive force that is applied to the magnetic core of the rotor being wound. This compressive force increases with the number of turns wound around the salient pole.

[0010] It should be noted that, in reality, to electrically isolate the conductor from the salient pole, an insulator is interposed between the conductor and the salient pole. This insulator often takes the form of insulating paper in the winding slots, and of flanges made of synthetic polymer material (plastic) arranged at each axial end of the lamination stack; these flanges are called coil head guides. The axial compression force is therefore also applied to the coil head guides.

[0011] The inventors observed that different lamination stacks constituting the magnetic cores of various wound rotors, due to their structure, exhibit elastic behavior with very low stiffness coefficients, on the order of 50 kN / mm (kiloNewtons per millimeter) in the elastic phase. During the winding of a salient pole in particular, the axial compressive force applied by the conductor wire brings the axial ends of the salient pole closer 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 bonding.

[0012] 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), 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, which corresponds to a stiffness coefficient of 0.81kN / mm.

[0013] During the winding of 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 conductor wire is placed at the axial ends of the rotor, is thus reduced and difficult to predict.

[0014] Currently, the trajectory of the needle relative to the salient pole that it winds is pre-programmed so that the conducting wire forms an orthocyclic stacking of the sections of the conducting wire in a portion of the surrounding coil the salient pole, assuming that there is no axial compression of the salient pole during winding.

[0015] In this application, "orthocyclic stacking" means a stacking that maximizes the filling ratio of the space allocated to the conductor around a salient pole with conductive wire. Thus, in an orthocyclic stacking, when the conductor has a round cross-section, a cross-section of the conductor in one winding layer is tangent to two cross-sections of the conductor in another winding layer, the centers of the three corresponding round cross-sections forming an equilateral triangle.

[0016] Figure 1 shows an axial cross-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 has a notch whose opening extends ortho-radially to receive the conducting wire of the coil 6. The conducting wire forming the coil 6 has, in this notch of the coil head guide 7, an orthocyclic stacking 60 of turns at the beginning of the winding, then winding defects 62, 64 corresponding to layers of conducting wire not stacked orthocyclically.

[0017] These winding defects 62, 64 are due to the axial compressive force F exerted by the tension of the conductor wire during winding, on the magnetic core 9 of the rotor and its coil head guide 7. Figure 1 shows that this axial compressive force F has deviated the position of the coil head guide 7 from 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.

[0018] 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 pre-programmed trajectory, but this requires a long and costly development time of the winding process for each structurally different rotor.

[0019] A pre-compression of the salient pole to be wound has been envisaged to better control the placement of the wires during winding, the first turns otherwise tending to relax as the winding of the salient pole progresses, but the inventors still frequently observe undesired 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 an automatic winding system for 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 conductor wire wound by the needle.

[0021] To this end, the invention proposes a method for winding a rotor body comprising a central part and several arms extending radially from the central part. The winding method uses an automatic winding system comprising a needle adapted to wind a conductive wire around one of the arms along a winding path comprising a passage through a winding notch between the arm and an adjacent arm. The passage extends from a first point located at a first axial end of the arm to a second point located at a second axial end of the arm. The winding method is characterized in that it comprises the following steps: - assigning a target position to the second point, - determining an axial deformation of the arm, - correcting the target position according to the previously determined axial deformation, resulting in a corrected target position, and - 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.

[0022] The winding process is implemented, in particular, by executing a computer program that defines the winding path of the needle. This path includes 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 zero speed and acceleration. They are located on either side of the branch at its axial ends, and their positions determine the correct placement of the conductor wire along an axial wall or an axial end of the branch.

[0023] 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, which would allow the conductor wire to form turns in an orthocyclic stacking pattern in the winding slot when the needle moves from the first point to the second point having this target position, and when the rotor body arm is not axially deformed. This target position of the assignment step is therefore an initial target position that can be that of a pre-programmed path, assuming there is no axial deformation, similarly to the prior art.

[0024] The invention corrects this target position in real time, the corrected target position being the position finally retained for the second point.

[0025] Thanks to the invention, the placement of the conducting wire between the first point and the second point corresponds to an orthocyclic stacking of turns of the conducting wire in the winding notch, since the second point takes into account the axial deformation exerted on the branch during the winding of the latter.

[0026] The different branches can be wound one after the other or at the same time depending on whether a conductor wire is used per branch or a single one for all branches.

[0027] The invention applies to a wound rotor of a radial flux electric machine, the wound rotor being salient pole, but is not limited to automotive applications.

[0028] The rotor body refers to a magnetic core of a wound rotor, formed for example from a stack of laminations, and optionally equipped with coil head guides. Each axial end of the rotor body is optionally equipped with one or more coil head guides depending on whether such a guide forms a star-shaped piece covering the axial ends of each salient pole formed by the magnetic core, or forms an insulator for only a portion of the salient poles.

[0029] Each of the rotor body arms therefore comprises a portion of the magnetic core forming a salient pole, and optionally portions of two coil head guides or two coil head guides, depending on whether these guides are located at the axial ends of the rotor body. The rotor body arms, with their respective coils, form magnetic poles of the wound rotor.

[0030] The salient poles can have different shapes, including within the same rotor. Each salient pole has at least one substantially parallelepiped-shaped portion receiving a coil of conducting wire. This portion is optionally extended at an external radial periphery of the salient pole by a pole head having ortho-radial extensions that hold the coil in position despite the centrifugal force when the rotor is in operation.

[0031] Furthermore, the conducting wire preferably has a round cross-section, but other cross-sections can be considered, for example square or rectangular cross-sections. Finally, the magnetic core is not necessarily made by stacking laminations; the invention applies to any magnetic core that is axially deformable during its winding.

[0032] 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.

[0033] 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 [Fig. 1]. By measuring or calculating the distance between, on the one hand, the point on the central part of the rotor body, this central part can be impacted by the axial compression but without deviating from the plane Given the orthogonal point and, on the other hand, the external radial endpoint of the branch, this deviation can be quantified. The point on the central part is preferably located on the axial end of the rotor body containing the second axial endpoint of the branch. This distance can be obtained, for example, using a distance sensor whose position is fixed relative to the central part.

[0034] 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 step calculates for example the coordinates of an image of the target position by a rotation centered at the intersection between the first and second lines and with an angle of deviation angle.

[0035] In this embodiment of the invention, the deflection angle corresponding to a rotation of the second axial end of the arm relative to the central part of the rotor body is used to correct the target position of the needle 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 arm, and from the dimensions of the magnetic core. The second 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 arm.

[0036] 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 process preferably includes as many steps for assigning a target position, determining an axial deformation, correction, and displacement as there are turns. The steps of the winding process are, for example, repeated for each turn formed by the needle around the branch, or only during the formation of certain turns. In particular, the positioning of the first turns generally does not require correction of the needle position.

[0037] Similarly, it is preferable to correct the position of the needle symmetrically when it positions the conducting wire in the other winding slot of the branch. More precisely, the path involves, for each turn to be formed, a first pass of the needle from the first point to the second point, a second pass 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 opposite a winding slot facing the winding slot of the branch, a third the winding process includes a step of assigning a target position for the fourth point, a step of correcting the target position for the fourth point based on a further step of determining an axial deformation of the branch, resulting in a corrected target position for the fourth point, and a further 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.

[0038] Of course, the positions of the third and first points are corrected according to the corrections applied respectively to the second and fourth points, but these corrections do not require determining a deformation of the magnetic core at the branch. Indeed, the orthoradial dimension of a branch is much smaller than its axial dimension, which limits the deformation of the branch in the orthoradial direction.

[0039] Furthermore, according to an optional feature of the winding process according to the invention, it includes a preliminary step of axial compression of the branch.

[0040] This preliminary step ensures good tension of the conductor wire and good retention of the wire around the branch, once the latter has been wound.

[0041] 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 is characterized in that it comprises: - means for assigning a target position to the second point, - means for determining an axial deformation of the arm, - 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 - means of moving the needle from the first point to the second point corresponding to the corrected target position.

[0042] The automatic winding system according to the invention therefore includes means for implementing the winding process according to the invention.

[0043] According to an 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 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.

[0044] 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 suitable to calculate the coordinates of an image of the target position by a rotation centered at the intersection between the first and second lines and with an angle of deviation angle.

[0045] The invention further relates to a computer program comprising program code instructions for executing the steps of the winding process according to the invention, when said program is executed on one or more processors.

[0046] The automatic winding system according to the invention and the computer program according to the invention have advantages similar to those of the winding process according to the invention.

[0047] Other features and advantages of the invention will become apparent from the following description on the one hand, and from several illustrative and non-limiting examples of embodiments given with reference to the accompanying schematic drawings on the other hand, in which:

[0048] [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 a portion of the axial end of the salient pole being shown,

[0049] [Fig.2] represents in perspective a rotor body intended to be wound according to a winding process according to the invention, in one embodiment of the invention,

[0050] [Fig.3] represents the rotor body of [Fig.2] in axial section, at the beginning of winding by an automatic winding system according to the invention, in one embodiment of the invention, a rotating shaft being inserted into the rotor body, and a compression device being placed at the ends of a branch of the rotor body,

[0051] [Fig.4] represents the winding of a branch of the rotor body of [Fig.2] at the beginning 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 a of its axial extremity portions, and on the other hand viewed from the side along its entire axial length,

[0052] [Fig.5] represents the winding of the rotor body branch of [Fig.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 viewed from the side along its entire axial length,

[0053] [Fig. 6] represents steps of the winding process according to the invention, according to the mode of realization mentioned in relation to [Fig.2], and

[0054] [Fig.7] represents the winding of the rotor body branch of [Fig.2] at the end of winding, this winding being carried out according to the winding process according to the invention mentioned in relation to [Fig.2], the branch being represented in an axial plane, by one of its axial end portions only.

[0055] In one embodiment of the invention, a winding method 100 according to the invention (referenced in [Fig. 6]) is used to wind a rotor body 1 shown in [Fig. 2] with a conductive wire 3 (shown in [Fig. 3]), here a copper wire with a round cross-section, and obtain a wound rotor. Other types of conductive wire are of course usable.

[0056] As shown in [Fig. 2], the rotor body 1 comprises a magnetic core 11 formed by an axial stack of magnetic laminations, the axial direction represented by an x-axis being parallel to an axis of rotation R of the wound rotor. The magnetic core 11 comprises a cylindrical central portion 112 having a recess 14 for the passage of a rotating shaft 15 (referenced in [Fig. 3]), and salient poles 114 extending radially from the cylindrical central portion 112.

[0057] The rotor body 1 also includes 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 has a central portion 162 and a recess that overlap respectively with the cylindrical central portion 112 of the magnetic core 11 and the recess 14, as well as arms 165 extending each from the central portion 162 to an external radial end 164 of the arm 165.

[0058] The arms 165 of the coil head guides 16 overlap one by one the salient poles 114 of the magnetic core 11, on either side of it, to form branches 12 of the rotor body 1, intended to be wound. The spaces between the branches 12 form winding slots, such as the winding slots referenced 12_1 and 12_2 in [Fig.2].

[0059] In this embodiment of the invention, the arms 12 of the rotor body terminate radially with ortho-radial extensions adapted to confine the winding between a central portion 10 (referenced [Fig.3]) of the rotor body 1 and these ortho-radial extensions, which form winding cavities on either side of each branch 12. The central portion 10 of the rotor body 1 corresponds to the cylindrical central portion 112 of the magnetic core 11 supplemented by the central portions 162 of each coil head guide 16.

[0060] 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 [Fig.3]) to form windings of conductive wire 3 around each branch 12.

[0061] 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 one side by the central portion 162 of the coil head guide 16 and on the other side by the external radial end 164 of the arm 165. The bottom of the winding notch 160 of the arm 165 is less extended axially 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 arm 12, have here a rounded shape and grooves 18 for positioning the conductor wire 3, which makes it easier to position the conductor wire 3 correctly by the needle 2.

[0062] The path of the needle 2 around a branch 12 of the rotor body 1 to form a loop around it is represented by dotted lines on [Fig.2].

[0063] A first part t1 of the path extends axially in the winding slot 12_1 from a first point pl located at a first axial end 13 of the arm 12, to a second point p2 located at a second axial end 17 of the arm 12. The first and second points pl and p2 are located opposite the winding slot 12_L

[0064] 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.

[0065] A third part t3 of the path extends axially in the winding slot 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 slot 12_2.

[0066] 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.

[0067] Points p1 to p4 are extreme points of the path taken by the needle 2 and correspond to zero velocity and acceleration of the needle 2. The path of the needle 2 is also defined by other intermediate points with non-zero velocity and / or acceleration. All points of the path are determined by a computer program whose execution allows the needle 2 to move. The computer 4 (referenced in [Fig. 3]) running this program is connected by computer to a robotic arm (not shown) capable of moving the needle 2 along the path determined by the computer program.

[0068] In this embodiment of the invention, the needle 2 moves axially to place the conductive wire 3 between points p1 and p2 on the one hand, and between points p3 and p4 on the other, the rotor body 1 being held fixed. Conversely, to place the conductive wire 3 orthoradially between points p2 and p3 on the one hand, and between points p4 and p1 on the other, the rotor is driven in rotation, and the needle 2 moves only to compensate for the circular motion of the rotor by a movement enabling the conductive wire 3 to be placed in a straight line. In alternative versions, the rotor remains fixed throughout the needle's movement, or the rotor moves to place the conductive wire 3 axially along the arms of the rotor body while the needle remains fixed.

[0069] The points pl to p4 are of course redefined for each new turn that the needle 2 forms around the branch 12. The determination of the points pl to p4 will be explained in more detail in relation to figures 4 to 7.

[0070] Figure 3 now illustrates an automatic winding system 40 according to the invention, in this embodiment of the invention, in the 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 attached to this robotic arm. In this embodiment of the invention, the automatic winding system 40 further comprises a compression device 5 mounted on a winding arm 12.

[0071] This compression device 5 comprises a first clamping jaw 52 disposed against the first axial end 13 of the arm 12, and a second clamping jaw 54 disposed against the second axial end 17 of the arm 12. These two clamping jaws are partially inserted into a guide 53, allowing them to slide translationally against each other, a screw 56 enabling this movement. The screw 56 is partially inserted into a threaded hole in the first jaw 52 and partially into a screw passage in the second jaw 54, this passage having a stop adapted to lock the head of the screw 56 by means of a spring 58.

[0072] The compression device 5 is used to compress the arm 12 before winding in order to limit the axial deformation of the arm 12 during winding and thus promote good positioning of the conductor wire 3. The spring 58 keeps the jaws 52, 54 tight against the arm 12 even when the conductor wire 3 adds axial compression to that already applied by the compression device 5 to the arm 12.

[0073] We now describe, with reference 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 arm 12 being wound is not axially deformed. In this case, the automatic winding system 40 does not implement the winding process 100 according to the invention, which assumes that an axial deformation of the arm 12 exists. However, these Figures 4 and 5 clearly illustrate the steps of the winding process 100 according to the invention when such a deformation exists.

[0074] Figure 4 shows the axial displacement of the needle 2 just before it reaches the second point p2, at the beginning of the winding of the arm 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. In this embodiment of the invention, the position of the needle 2 is defined by the position of a point A located on the needle 2. The position of the second point p2 is therefore that of point A of the needle 2 when it places the conductor wire 3 on a first winding layer and at a first radial position on the arm 12. The first winding layer is the one in contact with the rotor body 1, and the first radial position on the arm 12 corresponds to the position of the conductor 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 point A on a z-axis with radial direction, and by the axial position xA of point A on the x-axis.

[0075] The partial axial view on this [Fig.4] shows how the conductor 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 conductor wire 3 is shown there cut in the winding notch 160 to better visualize the position of the conductor wire 3 in the axial plane P.

[0076] Figure 5 shows the axial displacement of the needle 2 just before it reaches the second point p2, when the arm 12 is already almost fully 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 needle places the conductor wire 3 on a fourth winding layer, and at a radial position on the arm 12 closer to the radial end. external 164 of the arm 165, than of 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 according to the turn being formed.

[0077] In these two figures 4 and 5, the magnetic core 11 of the rotor body 1 does not undergo axial deformation; the radial positions zA and axial positions xA of the second points p2 of each turn of the conducting wire 3 are, for example, read from a table giving these values ​​for a given type of rotor body. It can be seen in the partial axial view of [Fig. 5] that the stacking of the turns is orthocyclic even though no correction of the positions of the second points p2 has been made.

[0078] The winding process 100 according to the invention is now described in relation to Figures 6 and 7, where the magnetic core 11 undergoes axial deformation during the winding of the rotor body 1. The winding process 100 is implemented by the automatic winding system 40.

[0079] A first step 105 of the winding process 100 is the pre-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 10kN between the axial ends 13, 17 of the branch 12. In an alternative embodiment, this pre-winding compression step 105 does not take place.

[0080] A second step 110 of the winding process 100 is the assignment of a target position to the second point p2, that is, the axial position xA and the radial position zA as assigned to the second point p2 in a manner similar to Figures 4 and 5 along the coil of conducting 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.

[0081] This target position (xA, zA) is read from a table containing the target positions of point A, for each turn of conductor wire 3 on each winding layer of branch 12. This table is stored in a memory of the computer 4, and its values ​​are predetermined for the type of rotor body corresponding to the rotor body 1. Alternatively, the target positions of the second point p2 are calculated by the computer 4 according to the type of rotor body corresponding to the rotor body 1.

[0082] A third step 120 of the winding process 100 is the determination of an axial deformation of the arm 12. Reference is made, of course, in this third step 120, even when not explicitly stated, only to the second axial end 17 of the arm 12 and to the axial end of the central part of the rotor body 1, extending from this second axial end 17 of the arm 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. Furthermore, the determination is made in the axial plane P comprising the second point p2 and passing through the axis of rotation R of the rotor body 1. It should be noted that in the partial axial view of [Fig.7], as in those of figures 4 and 5, the conductor wire 3 is shown cut in the winding notch 160 to better visualize the position of the conductor wire 3 in the axial plane P.

[0083] In this third determination step 120, the automatic winding system 40 uses a distance sensor 50, shown [Fig.7], which allows for the measurement or calculation of a distance ô 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 arm 12. This distance ô 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.

[0084] 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 ô obtained during this third determination step 120 makes it possible to quantify the deviation of the branch 12 with respect to a plane orthogonal to the axis of rotation R of the rotor body 1.

[0085] In this third determination step 120, a point on the outer radial end 164 of the arm 12 and a reference point on the central portion 162 are preferably chosen, located at the same axial level when the arm 12 is not axially deformed. In an embodiment of the invention in which this is not possible, the axial distance existing between these points before axially compressing the arm 12 is subtracted from or added to the distance ô obtained during this third determination step 120, so as to obtain a distance representative of the deviation of the arm 12 with respect to a plane orthogonal to the axis of rotation R of the rotor body 1.

[0086] In this third determination step 120, a deflection angle α of the arm 12 with respect to a plane orthogonal to the axis of rotation R of the rotor body 1 is then calculated. This deflection angle α is calculated knowing the radial dimension 1 of the arm 12. Since the coil head guide 16 strictly matches the radial dimensions of the magnetic core 11, this radial dimension 1 corresponds here to the distance, measured in the radial direction z, between the radial end of the salient pole 114 of the arm 12 and the cylindrical central portion 112 of the magnetic core 11. This distance is also the distance measured in the radial direction z, between the outer radial end 164 of the arm 165 and the central portion 162 of the coil head guide 16. We therefore have:

[0087] tan(a) = ô / 1

[0088] This deflection angle corresponds in the axial view of [Fig. 7], that is, 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 lines intersect at a point of intersection O.

[0089] Of course, the axial end of the salient pole 114 can deform non-linearly and not be planar. In this case, this deformation is approximated so as to obtain a deviation angle representative of this deformation and formed between two 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.

[0090] A fourth step 130 of the winding process 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 point A in the axial plane P passing through this point A and through the axis of rotation R, by an angle θ the deviation angle α calculated previously, and with center θ the point of intersection O between the first line d1 and the second line d2. Thus, we have:

[0091] z'A = sin (a) * xA + cos (a) * zA and

[0092] x'A = cos (a) * xA - sin (a) * zA , * being the multiplication operator.

[0093] A fifth step 140 of the winding process 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 conducting wire 3, on the order of 20 to 50 N (Newtons).

[0094] Then a sixth step 150 of the winding process 100 is the placement of the conducting wire 3 ortho-radially to the third point p3, this being corrected, with respect to its initially assigned position 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 conducting wire 3.

[0095] The winding process 100 then repeats the second to fifth steps of the winding process, adapting them to the fourth point p4, and places the conducting wire 3 ortho-radially to the first point pl in a manner similar to the sixth step, then repeats the second to sixth steps of the winding process as described previously, and so on.

[0096] In this embodiment of the invention, since the correction of the needle 2's position is performed both on the first part t1 of its path and on the third part t3 of its path t3, the automatic winding system 40 includes 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, accurate to within 10 microns. The measured distance θ can indeed be on the order of 0.5 mm for a compressive force of 20 kN, the deformation angle being in this case on the order of two degrees.

[0097] The computer 4 comprises at least one processor, random access memory, 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 process 100. The first step 105 can also be controlled by the computer 4 if it includes means for actuating the compression device 5.

[0098] Of course, the invention is not limited to the examples just described and many modifications can be made to these examples without departing from the scope of the invention.

Claims

Demands

1. A winding method (100) for a rotor body (1) comprising a central part (10) and several arms (12) extending radially from the central part (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 arms (12) along a winding path comprising a passage through a winding slot (12_1) between the arm (12) and an adjacent arm, the passage extending from a first point (p1) located at a first axial end (13) of the arm (12) to a second point (p2) located at a second axial end (17) of the arm (12), the winding method (100) being characterized in that it comprises steps of: - assigning (110) a target position (xA, zA) at 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), displacement (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. A winding method (100) for a rotor body (1) according to claim 1, wherein the arm (12) extends radially from the central part (10) to an external radial end of the arm (12), the step of determining an axial strain (120) comprises obtaining a representative value of a distance (o) 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 arm (12) at its second axial end (17).

3. A method for winding (100) a rotor body (1) according to claim 1 or 2, wherein the arm (12) is formed at least in part by a magnetic core (11) delimited at the second axial end (17) of the arm (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 right (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 centered at the intersection (0) between the first and second lines (dl, d2) and with an angle of deviation (a).

4. A winding method (100) for a rotor body (1) according to any one of claims 1 to 3, wherein the path includes several first points (pl) and several second points (p2) to form a number of turns corresponding to different radial positions on the arm (12), and to different winding layers, the winding method (100) includes as many steps of assigning (110) a target position (xA, zA), determining (120) an axial deformation, correction (130) and displacement (140) as the number of turns.

5. A method for winding (100) a rotor body (1) according to any one of claims 1 to 4, wherein the path comprises, for each turn to be formed, a first pass of the needle (2) from the first point (p1) to the second point (p2), a second pass 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 arm (12) and opposite a winding notch (12_2) to the winding notch (12_1) with respect to the arm (12), a third pass of the needle (2) from the third point (p3) to a fourth point (p4) located at the first axial end (13) of the arm (12) and opposite the winding notch (12_2), and a fourth pass in the direction orthoradial from the fourth point (p4) to the first point (pl), the winding process (100) includes another step of assigning (110) a target position (xA, zA) for the fourth point (p4),another correction step (130) of the target position (xA, zA) for the fourth point (p4) as a function of another determination step (120) of an axial deformation of the branch (12), resulting in a corrected target position (x'A, z'A) for the fourth point (p4), and another displacement step (140) of 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 for winding (100) a rotor body (1) according to any one of claims 1 to 5, comprising a preliminary step of axial compression (105) of the arm (12).

7. An automatic winding system (40) for a rotor body (1) comprising a central part (10) and several arms (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 arms (12) along a winding path comprising a passage through a winding slot (12_1) between the arm (12) and an adjacent arm, the passage extending from a first point (p1) located at a first axial end (13) of the arm (12) to a second point (p2) located at a second axial end (17) of the arm (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 of an axial deformation of the branch (12), - means of 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 (p1) 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 arm (12) extends radially from the central part (10) to an external radial end of the arm (12), the means for determining an axial deformation comprise a distance sensor (50) capable of enabling the obtaining of a value representative of a distance (o) 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 arm (12) at its second axial end (17).

9. An automatic winding system (40) for a rotor body (1) according to claim 7 or 8, wherein the arm (12) is formed at least in part by a magnetic core (11) delimited at the second

10. 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 deviation 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 suitable for calculating the coordinates of an image of the target position (xA, zA) by a rotation centered at the intersection (O) between the first and second straight lines (dl, d2) and with an angle of deviation angle (a). Computer program comprising program code instructions for performing the steps of the winding process (100) according to any one of claims 1 to 6, when said program is executed on one or more processors.

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