System and method for automatically winding a rotor body

Abstract

The invention relates to a system for automatically winding a rotor body comprising a plurality of branches extending radially from a central part, the automatic winding system comprising a tool (7) for supporting a needle (72) for supplying conductive wire (8) and means for moving the support tool (7) relative to the branches, in at least one direction of movement, the needle (72) being oriented radially, the support tool (7) comprising means for preforming the conductive wire (8) leaving the needle (72), the needle (72) and the preforming means being capable of delimiting a segment of conductive wire (8) forming a deflection angle with respect to the direction of movement, the automatic winding system being characterized in that the support tool (7) comprises modification means capable of modifying the position of the preforming means relative to the needle (72) and the length of the segment.

Description

System and method for automatic winding of a rotor body

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

[0002] The electrical machines of electric or hybrid vehicles generally consist of a wound stator and a rotor whose magnetic poles contain permanent magnets or a winding; in the latter case, the rotor is called wound. Wound rotors are generally made primarily of:

[0003] - 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 having a recess allowing the insertion into the stack of sheets of a shaft for rotating the wound rotor; and

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

[0005] It should be noted that in this definition, 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 an ortho-radial or angular 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 from 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] As shown, the automatic winding of a rotor uses a needle 32 through which the conductor wire 8 to be wound passes. The needle 32 is held by a support tool 30, set in motion, for example, by a robotic arm.

[0008] In certain wound rotor technologies, in order to best fill the winding slots with conductive wire and thus optimize the electrical performance of the wound rotor, the different layers of conductive wire 8 must not have any unnecessary free space between them or with the salient pole 12. An orthocyclic stacking of conductive wire 8 is for example used to optimize the filling of the winding slots with conductive wire 8.

[0009] To achieve this, a significant tension, on the order of 20 to 50 N (Newtons), is applied to the conductor wire 8 during its winding around the salient pole 12. This ensures that the conductor wire 8 remains securely positioned in the winding slot, even during the operation of the electric machine when the conductor wire is subjected to centrifugal force. Such a tension is necessary to meet various technological constraints, notably to account for the axial compression of the magnetic core during winding, but also to ensure optimal proximity between the conductor wire 8 and the salient pole 12, or more precisely, between the conductor wire 8 and the rotor arm containing the salient pole 12 and the insulating guards for the salient pole 12.

[0010] Each salient pole 12 of the rotor is electrically insulated from the conductor wire 8, for example by insulating paper at the winding slots, and by winding guides 2 made of synthetic polymer material (plastic) at the axial ends of the salient pole 12. The rotor arm formed by the salient pole 12 equipped with the winding guides 2 has a section with rounded corners, thus facilitating the winding of the rotor arm.

[0011] To allow the conductor wire 8 to best conform to the shape of the rotor arm, the support tool 30 includes, downstream of the movement of the needle 32, a preforming rod 34 which allows the conductor wire 8 exiting the needle 32 to be brought closer to the surface to be wound, by exerting on the conductor wire 8 a tension directed partly orthogonally to the length of the conductor wire 8. This tension exerted by the preforming rod 34 is added to the tension exerted on the conductor wire 8 according to its length by a device upstream of the needle 32.

[0012] As shown on the left side of the diagram, during the winding of the rotor arm, the needle 32 winds the conductor wire 8 around the rotor arm, which includes the salient pole 12 and the winding guides 2, passing axially along the axial direction X between the arm and an adjacent arm. During this passage, the preforming rod 34 presses on the conductor wire 8 towards the rotor arm, facilitating correct shaping and positioning of the conductor wire 8 on the arm. The radial direction is represented by the Y-axis and the ortho-radial direction by the Z-axis in this diagram.

[0013] When the needle 32 then passes ortho-radially along an axial end of the branch, as shown on the right side of the figure, the rod 34 no longer presses on the conducting wire, which forms a bump 80 in relation to the corner of the branch whose shape it should follow.

[0014] This raised section prevents, once the conductor wire is wound under tension, the insertion of retaining wedges into the winding slots, without damaging or altering the conductor wire's position within the slots. This insertion of retaining wedges occurs before the winding is impregnated with insulating resin. The retaining wedges maintain the winding's shape before impregnation and then prevent any movement of the winding due to centrifugal force when the rotor is running.

[0015] One solution to prevent the formation of these bumps, due to a release of tension in the wire when the needle 32 passes along a corner of the rotor arm, is to further increase the tension of the conductor wire during its winding.

[0016] However, this assumes that the conductor wire must be able to withstand an even higher voltage than currently applied, requiring a higher quality conductor wire and therefore a higher cost. Furthermore, it implies accepting elongation of the conductor wire, thus reducing its cross-sectional area, which in turn increases its resistance, inversely proportional to its cross-sectional area. Increased resistance of the conductor wire means increased Joule losses during rotor operation, which is undesirable.

[0017] The present invention aims to remedy at least in part the aforementioned drawbacks by providing an automatic winding system and method, which makes it possible to reduce or even eliminate the bumps formed by the conductor wire around the corners of the rotor arms during their winding.

[0018] To this end, the invention proposes 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 support tool for a wire feed needle and means for moving the support tool relative to the branches, in at least one direction of movement, the needle being oriented radially when the support tool is moved by the means of movement, the support tool comprising means for preforming the wire exiting the needle, the needle and the preforming means being capable of delimiting a segment of wire forming an angle of deviation with respect to the direction of movement,The automatic winding system is characterized in that the support tool includes modification means capable of changing the segment length by modifying the position of the preforming means relative to the needle.

[0019] The means of modification are, for example, more capable of modifying the angle of deviation.

[0020] Thanks to the invention, the preforming means are able to remain in contact with the conductive wire while the needle goes around a corner of the rotor branch, and thus to reduce or even eliminate the bumps formed by the conductive wire at the corners of the rotor branch, without having to increase a longitudinal tension exerted on the conductive wire upstream of the preforming means.

[0021] As explained in relation to the prior art, preforming means are, for example, complementary to wire tensioning means, upstream of the preforming means, particularly when the winding creates an orthocyclic stacking of the conductor wire. In this application, "orthocyclic stacking" means a stacking that maximizes the conductor wire filling ratio of the space allocated to the conductor wire around a branch. Thus, in an orthocyclic stacking, when the conductor wire has a round cross-section, a cross-section of conductor wire in one winding layer is tangent to two cross-sections of conductor wire in another winding layer, the centers of the three corresponding round cross-sections forming an equilateral triangle.

[0022] Furthermore, the direction of movement varies depending on the position of the needle relative to the winding arm. Specifically, the direction of movement is axial in the winding slots and orthoradial relative to the rotor arms. In addition, the rotor body includes, for example, a magnetic core and electrically insulating shields, with each rotor arm incorporating a portion of the magnetic core and a portion of the electrically insulating shields.

[0023] In one embodiment of the invention, the modification means include, for example, a shaft with an axis parallel to a main extension direction of the needle, and an arm having a first end mounted pivotally around the shaft, the preforming means being fixed to a second end of the arm, distinct from the first end.

[0024] It is understood that rotating the arm allows the deflection angle and wire length to be modified. This embodiment of the invention avoids having to modify the programming of the support tool's movement. For example, the movement means are adapted to move the support tool so that the shaft and the needle are aligned on a straight line parallel to the direction of movement over at least a portion of a winding path around the rotor arm, or even over the entire winding path. The shaft may optionally be mounted to move in translation on the support tool. In this way, the modification means are adapted to change the position of the shaft relative to the needle on the support tool.

[0025] In one embodiment of the invention, in which the shaft and the needle are aligned on a straight line parallel to the direction of travel along at least a portion of a winding path, the preforming means comprise, for example, a rod capable of pushing the conductor wire towards a branch, the distance between the parallel line and the rod varying according to a winding layer being formed on the branch. With the needle, for example, positioned angularly in the middle of a winding notch, the distance between the parallel line and the rod is at its maximum during the formation of the first winding layer, in direct contact with the branch, and at its minimum during the formation of the last winding layer, the outermost layer of the branch.

[0026] For the sake of indication, in these embodiments of the invention in which the modification means include a shaft with an axis parallel to a main extension direction of the needle and an arm, the angle between the arm and the direction of movement is, for example, able to vary between 5 and 40 degrees.

[0027] According to an optional feature of the invention, the needle comprising a main part having an axis of symmetry and an exit mouth for the conducting wire, eccentric with respect to the main part, the support tool comprises means for rotating the needle around the axis of symmetry.

[0028] This feature allows for an additional degree of freedom in the positioning of the conductor wire at the needle's exit, and makes it easier to adjust the tension of the conductor wire at the needle's exit.

[0029] Furthermore, the preforming means may include means for rotating the rod about itself, around an axis running longitudinally through the rod, this axis being parallel to the main extension direction of the needle. According to another optional feature of the invention, the automatic winding system according to the invention includes means for rotating the support tool about an axis of rotation of the support tool, the axis of rotation being radial during the operation of the automatic winding system. This feature also allows for an additional degree of freedom in the positioning of the conductor wire exiting the needle, and for easier adjustment of the tension of the conductor wire exiting the needle.

[0030] The automatic winding system according to the invention may include means for measuring wire tension to allow adjustment of this tension based on the position of the needle relative to the branch being wound. Adjusting the wire tension uses the means for modifying and / or rotating the needle and / or the support tool. Preferably, however, the positions of the preforming means, the support tool, and the needle are pre-programmed, such that each position of the needle around the branch being wound corresponds to a position of the preforming means relative to the needle, an angular position of the needle around the axis of symmetry relative to an initial angular position, and an angular position of the support tool relative to the direction of travel.

[0031] In one embodiment of the invention, the movement means comprise, for example, means for translating the support tool along an axial direction, in a winding slot delimited by a first branch and a second branch adjacent to the rotor body, from a first point located opposite one axial end of the winding slot to a second point located opposite another axial end of the winding slot, the movement means also comprising means for rotating the rotor around an axis of rotation of the rotor, the rotation means being capable of bringing the support tool from the second point to a third point located angularly opposite another winding slot delimited by the second branch and by a third branch adjacent to the second branch.

[0032] Thus, in this embodiment of the invention, the movement of the needle relative to the second arm of the rotor uses a translation of the support tool, during which the support tool axially traverses a winding slot, the rotor being fixed, followed by a rotation of the rotor, during which the support tool remains fixed relative to the ground, but unwinds the conductor wire on one axial end of the arm. Between the translation and the rotation, the support tool is, for example, rotated 90 degrees to follow the new ortho-radial direction of movement.

[0033] The invention also relates to a method for automatically winding a rotor body comprising a central part and several branches extending radially from the central part, using an automatic winding system according to the invention, comprising a winding step of one of the branches of the rotor body by winding a conductive wire around the branch, the winding step comprising a modification of the position of the preforming means relative to the needle, so as to modify the length of a segment of conductive wire located between the needle and the preforming means.

[0034] In one embodiment of the automatic winding process according to the invention, the modification means comprise a shaft with an axis parallel to a principal extension direction of the needle and an arm having a first end pivotally mounted around the shaft. The preforming means are attached to a second end of the arm, separate from the first end. During the winding step, as the conductor wire being wound forms a winding layer, the preforming means maintain the conductor wire in contact with a winding layer immediately below the layer being formed, or in contact with the branch being wound. This embodiment makes it possible to completely eliminate the bumps formed in the prior art by the conductor wire near the corners of the branch.

[0035] 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 attached schematic drawings on the other hand, in which:

[0036] already commented on in relation to the prior art, represents in a cutting plane extending axially and angularly, the winding of a rotor arm by a support tool, on the one hand when the support tool is positioned in a winding notch, and on the other hand when the support tool is positioned at an axial end of the arm being wound,

[0037] represents in perspective a rotor wound by an automatic winding process according to the invention, in one embodiment of the invention,

[0038] represents a support tool for a wire feed needle and preforming means, of an automatic winding system according to the invention, in one embodiment of the invention,

[0039] represents, in a cutting plane extending axially and angularly, a rotor half-branch as well as several configurations of the support tool, particularly during the winding of the rotor half-branch, according to the automatic winding process according to the invention mentioned in relation to the,

[0040] represents, in a cutting plane extending axially and angularly, the winding of a rotor arm by the support tool, according to the automatic winding process according to the invention mentioned in relation to the, on the one hand when the support tool is positioned in a winding slot, and on the other hand when the support tool is positioned at an axial end of the arm being wound, and

[0041] represents steps in the winding process according to the invention as mentioned in relation to the.

[0042] According to one embodiment of the invention, an automatic winding process 100 (referenced) according to the invention makes it possible to obtain a wound rotor 1 shown. This wound rotor 1 comprises elements identical to those of the, and these identical elements are referenced in the same way as in the.

[0043] The wound rotor 1 comprises a rotor body 10 having an axial stack of magnetic steel laminations, the axial direction X being parallel to an axis of rotation R of the wound rotor. This axial stack of laminations forms a magnetic core having on one side a substantially cylindrical central part, hollowed out in its center to allow insertion of a rotating shaft 5 of the rotor 1, and on the other side salient poles 12 extending radially from the central part.

[0044] The salient poles 12 are regularly distributed around the central portion and each, once wound, forms a pair of magnetic poles of the rotor 1. Each salient pole 12 extends axially from one axial end of the magnetic core to the other. It comprises a trunk and a head, the trunk being substantially parallelepiped-shaped and designed to receive a winding of conductive wire 8. The trunk connects the central portion of the magnetic core to the head, which extends orthoradially on either side of the trunk along the entire axial length of the salient pole 12, so as to radially hold the winding of conductive wire 8 on the portions of this winding located between two adjacent salient poles 12, that is, in winding slots. These portions of the winding are referred to hereafter as axial portions of the winding.

[0045] Each winding slot between a first salient pole 12 and a second salient pole 12 adjacent to the first salient pole 12 is lined with insulating paper. The winding slot actually comprises two winding cavities: a first winding cavity containing an axial portion of the winding of conducting wire 8 around the first salient pole 12, and a second winding cavity containing an axial portion of the winding of conducting wire 8 around the second salient pole 12.

[0046] The magnetic steel sheets forming the magnetic core are formed by cutting from a large sheet, and form U-shaped winding cavities, with the arms of the U being at right angles to the base of the U.

[0047] Each axial end of the magnetic core is flanked by a winding guide 2 made of molded, electrically insulating synthetic polymer material, and receiving ortho-radial portions of the conductor wire windings 8 of the rotor 1. Each winding guide 2 has an annular central portion, and arms extending radially from the central portion, each arm covering the axial end of a salient pole 12 of the rotor body 10.

[0048] The rotor body 10 comprises the magnetic core, insulating papers, winding guides 2, and windings around the rotor arms 1. Each rotor arm thus has a salient pole 12 flanked by two winding guide arms 2 and insulating paper. The winding guide arms 2 have rounded angular ends at the wound portion of these arms.

[0049] As shown in a cross-section extending axially and angularly across a wound portion of a rotor arm, the cross-sections of the two winding guide arms 2 allow the corners of the rotor arm to be rounded. In an alternative embodiment of the invention, the salient poles are flanked by steel flanges having rounded edges, and each rotor arm to be wound comprises only one salient pole and insulating paper disposed on the winding surfaces of the salient pole.

[0050] Returning to the previous point, in this embodiment of the invention, each winding guide arm 2 has, at its free radial end, a rim covering the axial end of the head of a salient pole 12 and extending axially and angularly so as to axially and angularly cover the winding layers formed around the wound portion of the arm. In other words, the rim is square with the rest of the arm.

[0051] The watch also has a rotor coil retaining ring 6, not yet mounted on one of the axial ends of the rotor body 10. This retaining ring 6 is intended to cover angularly and axially the edges mentioned above, of the arms of one of the winding guides 2. It allows the rotor coils formed on this winding guide 2 to be kept in position during the operation of the rotor 1, despite the centrifugal force.

[0052] Furthermore, in this embodiment of the invention, the winding of each arm of the rotor 1 is arranged so that the conductive wire 8 forms an orthocyclic stack of conductive wire 8 all around the arm of the rotor 1. The conductive wire 8 is here a copper wire with a round cross-section, but other types of conductive wire are of course usable. Retaining wedges 4 are also inserted into the winding slots to hold these orthocyclic stacks in position before the windings of the rotor 1 are impregnated with insulating resin, and subsequently to prevent any deformation of these windings due to the centrifugal force created by the rotation of the rotor during operation.

[0053] In an alternative embodiment, the rotor winding using the winding system according to the invention is not orthocyclic. Indeed, while the invention makes it easier to create an orthocyclic winding, it can also be used to create other types of windings.

[0054] As shown, in this embodiment of the invention, an automatic winding system for the rotor body 10 according to the invention comprises a support tool 7 including a plate 70, a needle 72 for supplying conductive wire 8, means for preforming the conductive wire 8 at the exit of the needle 72, and means for modifying the position of the preforming means.

[0055] The needle 72 is fixed orthogonally to the plate 70. The needle 72 extends radially when the automatic winding system is in operation, the radial direction being defined relative to the rotor 1. More precisely, the needle 72 comprises a main part having an axis of symmetry y1 and a conductor wire outlet 8, eccentric with respect to the main part. The support tool 7 includes means for rotating the needle 72 about its axis of symmetry y1, independently of any movement of the plate 70. For example, the needle 72 is rotatably mounted on the plate 70, being mechanically connected to an output shaft of an electric motor of the automatic winding system.

[0056] In an alternative embodiment, the support tool 7 does not include means for rotating the needle 72 around its axis of symmetry y1, independently of the plate 70.

[0057] Returning to the main embodiment of the invention, the automatic winding system further comprises means for rotating the support tool 7 around itself, more precisely around an axis of rotation y3 of the support tool 7, passing through the center of the plate 70. The axis of rotation y3 of the support tool 7 is orthogonal to the plate 70 and is therefore radial during the operation of the automatic winding system.

[0058] The automatic winding system more generally includes means for moving the support tool 7 relative to a branch of the rotor 1 to be wound, in particular means for axially moving the support tool 7 in a winding notch of the rotor 1 to be wound, and means for rotating the rotor 1 to be wound independently of the support tool 7, i.e. that the support tool 7 remains fixed relative to the ground during a rotation of the rotor 1 to be wound by these rotation means.

[0059] In an alternative embodiment, the means of movement are capable of moving the support tool 7 axially and angularly without rotating the rotor.

[0060] Furthermore, the preforming means here are a rod 78, fixed to the plate 70 by means of modifying the position of the rod 78 relative to the needle 72. The modification means comprise a shaft 74 with axis y2 parallel to the main extension direction of the needle 72, and an arm 76 mounted to pivot around the shaft 74, the rod 78 being fixed to the free end of the arm 76. The shaft 74 is fixed to the plate 70 by extending orthogonally to it. In other words, the shaft 74 extends radially when the automatic winding system is in operation. The arm 76 extends orthogonally to the shaft 74 and can move in a plane parallel to a main extension plane of the plate 70, as shown.

[0061] The preforming means may also include means for rotating the rod 78 about itself, around an axis y4 passing longitudinally through the rod 78, this axis y4 being parallel to the main extension direction of the needle 72. Furthermore, the shaft 74 can be mounted to move in translation on the plate 70, so as to reduce or increase the distance between the shaft 74 and the needle 72. The plate 70 includes, for example, a rail on which the shaft 74 is slidably mounted, the rail being parallel to a straight line on which the shaft 74 and the needle 72 are aligned. This arrangement allows the rod 78 to reach even more positions, which may be necessary, depending on the configuration of the rotor to be wound and the length of the plate 70, to constrain the conductor wire 8 as close as possible to the surface to be wound.

[0062] In the figure, the shaft 74 and the needle 72 are aligned on a straight line D parallel to a direction of movement of the support tool 7 in a winding slot adjacent to a branch of the rotor 1 being wound. The direction of movement and the straight line D are therefore parallel to the axial direction X. The straight line D is here midway between the branch being wound and a branch adjacent to the branch being wound, that is to say, it is located angularly at the midpoint of the winding slot.

[0063] Once the branch is wound, the conducting wire extends around the branch up to a limit 82 shown as a dotted line on the diagram. The rotational movement of the arm 76 around the shaft 74 brings the rod 78 into contact with the conducting wire 8 regardless of the wire's position between the branch and the limit 82.

[0064] In the position of the arm 76 shown in solid line, the rod 78 applies tension to the conductive wire 8 at a distance d0 from the needle 72, along the angular direction Z. In another position of the arm 76 shown in dashed line, the rod 78 applies tension to the conductive wire 8 at a distance d1 from the needle 72, along the angular direction Z, this distance d1 being strictly greater than the distance d0. Indeed, the arm shown in dashed line represents a passage of the support tool 7 at the beginning of the winding of the rotor arm 1, while the arm 76 shown in solid line represents a passage of the support tool 7 after several layers of winding of the rotor arm 1. It can be observed that from the first layer of winding, the rod 78 maintains the conductive wire 8 in contact with the arm being wound.

[0065] The distance between the parallel line D and the rod 78, orthogonal to the direction of movement, therefore varies depending on the winding layer being formed on the branch. This distance is greater the closer the winding layer is to the branch being wound.

[0066] Furthermore, the rounded solid arrows on the diagram show the possible directions of rotation of the arm 76 around the shaft 74. The arm 76 can bring the rod 78 to one side or the other side of the shaft 74 relative to the needle 72, which can allow the position of the rod 78 relative to the needle 72 to be changed. However, in the automatic winding method 100 according to the invention, described now in relation to Figures 5 and 6, the rod 78 is always located on the same side of the shaft 74 relative to the needle 72, during the winding of a branch of the rotor 1.

[0067] The automatic winding process 100 includes a winding step 101 per branch of the wound rotor 1. Since the rotor 1 has eight branches, in this embodiment of the invention, this winding step 101 is repeated eight times.

[0068] Each winding step 101 includes a first initialization substep 102, during which the conductive wire 8 exiting the needle 72 is fixed, for example, to an attachment point on the shaft 5 of the rotor 1. Then, the support tool 7 is positioned in a winding slot at a first referenced point p1, located opposite an axial end of the winding slot. More precisely, the center of the plate 70 is brought to this point p1, the axis of symmetry of the needle 72 being oriented radially.

[0069] During this first initialization sub-step 102, a voltage is applied to the conductor wire 8 by means of tensioning the conductor wire, present in the automatic winding system, upstream of the supply of conductor wire 8 by the needle 72. The voltage applied to the conductor wire is for example between 10 and 50N, and is maintained throughout the winding step 101.

[0070] During a second substep 104 of the winding step 101, the means for moving the support tool 7 move the support tool 7 along the axial direction X in the winding slot, the needle 72 being positioned angularly in the middle of the winding slot, up to a second point p2 located opposite the other axial end of the winding slot.

[0071] This second sub-step 104 is illustrated on the left side of the diagram. During a portion of the path from the first point p1 to the second point p2, the needle 72 and the shaft 74 are aligned on a straight line D parallel to the axial direction X. During this portion of the path, the conductive wire 8 exiting the needle 72 forms a segment 84 delimited on one side by the needle 72 and on the other by the point of contact between the rod 78 and the conductive wire 8. This segment 84 has a length l1 and forms a deflection angle α1 with respect to the direction of movement of the support tool 7. The arm 76 forms an angle β1 with the direction of movement. This angle β1 between the arm 76 and the direction of movement allows the conductive wire 8 to be in contact with the rotor arm 1 during this portion of the winding path.The angle β1 between the arm 76 and the direction of travel is, for example, pre-programmed in the automatic winding system and is constant along this entire portion of the winding path. Consequently, along this entire portion of the winding path, the length l1 of the segment and the deflection angle α1 are also constant. Furthermore, the arm 76 applies an additional tension to the conductor wire 8, compared to the means for tensioning the conductor wire 8, which is constant along this entire portion of the winding path.

[0072] In this second substep 104, as soon as the needle 72 reaches the rounded portion of a corner of the rotor arm 1 being wound, the automatic winding system rotates the support tool 7 around its axis of rotation y3 so that the needle 72 follows the shape of the surface to be wound. The winding system also modifies the angle between the arm 76 and the direction of travel, so as to change the position of the rod 78 so that it holds the conductor wire 8 against the rounded surface of the corner of the rotor arm 1, which also changes the length of the conductor wire segment between the needle 72 and the rod 78, as well as the angle of deflection between the segment and the direction of travel.

[0073] Then, during a third sub-step 106 of the winding step 101, illustrated on the right-hand side of the diagram, the movement means rotate the rotor 1 so that the fixed support tool 7 moves relative to the rotor 1 in the angular direction Z, from the second point p2 to a third point p3. The third point p3 is located opposite an axial end of a winding slot opposite to the one that the support tool 7 has just passed through with respect to the branch of the rotor 1 being wound.

[0074] This third substep 106 involves a modification of the angle between the arm 76 and the direction of movement, here angular, the modified angle being β2 on the. This modification changes the position of the rod 78 so that it holds the conductive wire 8 against the surface of the axial end of the rotor arm 1. The length of the segment 86 of conductive wire 8 between the needle 72 and the rod 78 then becomes the length l2 illustrated, strictly smaller than the length l1 during the axial movement of the needle 72. The deflection angle between the segment 86 and the direction of angular movement is also modified and becomes the deflection angle α2 on the.

[0075] For the sake of indication, in this embodiment of the invention, the angle between the arm 76 and the direction of movement is able to vary between 5 and 40 degrees.

[0076] In this third substep 106, as soon as the needle 72 reaches the rounded portion of another corner of the rotor arm 1 being wound, the automatic winding system rotates the support tool 7 around its axis of rotation y3 so that the needle 72 follows the shape of the surface to be wound. The angle between the arm 76 and the direction of travel is modified so that the rod 78 holds the conductor wire 8 against the rounded surface of this other corner of the rotor arm 1.

[0077] When the support tool 7 arrives at the third point p3, the movement means axially move the support tool 7, in a fourth step 108 of the winding step 101, from the third point p3 to a fourth point p4 located opposite the other axial end of the winding notch in which the support tool 7 is located. This step is similar to the second step 104 of the winding step 101.

[0078] In particular, as soon as the needle 72 arrives opposite the rounded portion of another corner of the branch of the rotor 1 being wound, the automatic winding system rotates the support tool 7 around its axis of rotation y3 so that the needle 72 follows the shape of the surface to be wound.

[0079] Then, in a fifth substep 110 of the winding step 101, the movement means rotate the rotor 1 so that the fixed support tool 7 moves relative to the rotor 1 in the angular direction Z, from the fourth point p4 to the first point p1. This step is similar to the third step 106 of the winding step 101.

[0080] Finally, during a sixth sub-step 112 of the winding step 101, the movement means adjust the radial position of the support tool 7 so that the conductor wire 8 exiting the needle 72 is radially right next to the first turn of conductor wire 8 that has just been made.

[0081] Then the winding system repeats the second through sixth substeps as many times as a predetermined number K of turns in each winding layer. Once the first winding layer is complete, the winding system repeats these substeps to create a predetermined number M of winding layers.

[0082] When the conductor wire 8 is wound over an already formed winding layer, in these substeps the angle between the arm 76 and the direction of travel is adjusted so that the rod 78 holds the conductor wire 78 against this winding layer.

[0083] The winding system may also include means for measuring the wire tension and adjusting the angle between the arm 76 and the direction of travel so that the variation in tension applied to the conductor 8 is not less than a predetermined threshold. In other words, the winding system adjusts the angle between the arm 76 and the direction of travel so that the length of the unwound conductor 8 does not decrease due to retraction of the conductor 8 caused by a release of tension on the conductor.

[0084] 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. In particular, the features of different embodiments of the invention can be combined to carry out the invention, provided that these embodiments are not incompatible with each other.

Claims

Automatic winding system of a rotor body (10) comprising a central part and several arms (12) extending radially from the central part, the automatic winding system comprising a support tool (7) for a needle (72) for feeding conductive wire (8) and means for moving the support tool (7) relative to the arms (12), in at least one direction of movement, the needle (72) being oriented radially when the support tool (7) is moved by the means of movement, the support tool (7) comprising means for preforming the conductive wire (8) at the exit of the needle (72), the needle (72) and the preforming means being able to delimit a segment (84, 86) of conductive wire (8) forming a deflection angle (α1, α2) with respect to the direction of movement,The automatic winding system is characterized in that the support tool (7) comprises modification means capable of modifying the position of the preforming means relative to the needle (72) and the length (l1, l2) of the segment (84, 86). Automatic winding system according to claim 1, wherein the modification means are further adapted to modify the deflection angle (α1, α2). Automatic winding system according to claim 1 or 2, wherein the modification means comprise a shaft (74) with axis (y2) parallel to a main extension direction of the needle (72), and an arm (76) having a first end mounted pivotally around the shaft (74), the preforming means being fixed to a second end of the arm (76), distinct from the first end. Automatic winding system according to claim 3, wherein the shaft (74) and the needle (72) are aligned on a straight line (D) parallel to the direction of travel over at least a portion of a winding path, and wherein the preforming means comprise a rod (78) capable of pushing the conducting wire (8) in the direction of a branch (12), the distance between the parallel straight line (D) and the rod (78) varying according to a winding layer being formed on the branch (12). Automatic winding system according to any one of claims 2 to 4, wherein the angle (β1, β2) between the arm (76) and the direction of movement is able to vary between 5 and 40 degrees. Automatic winding system according to any one of claims 1 to 5, in which, the needle (72) comprising a main part having an axis of symmetry (y1) and an exit mouth of the conductor wire (8), eccentric with respect to the main part, the support tool (7) comprises means for rotating the needle (72) around the axis of symmetry (y1). Automatic winding system according to any one of claims 1 to 6, comprising means for rotating the support tool (7) around a rotation axis (y3) of the support tool (7), the rotation axis (y3) being radial during the operation of the automatic winding system. An automatic winding system according to any one of claims 1 to 7, wherein the movement means comprise means for translating the support tool (7) along an axial direction (X), within a winding slot delimited by a first branch (12) and a second branch (12) adjacent to the rotor body (10), from a first point (p1) located opposite one axial end of the winding slot to a second point (p2) located opposite another axial end of the winding slot, the movement means also comprising means for rotating the rotor (1) about an axis of rotation (R) of the rotor (1), the rotation means being capable of bringing the support tool (7) from the second point (p2) to a third point (p3) located angularly opposite another winding slot delimited by the second branch (12) and by a third branch (12) adjacent to the second branch (12). Automatic winding method (100) of a rotor body (10) comprising a central part and several branches (12) extending radially from the central part, using an automatic winding system according to any one of claims 1 to 8, comprising a winding step (101) of one of the branches (12) of the rotor body (10) by winding a conductive wire (8) around the branch (12), the winding step (101) comprising a modification of the position of the preforming means relative to the needle (72) so as to modify the length (l1, l2) of a segment of conductive wire (8) located between the needle (72) and the preforming means. Automatic winding method (100) according to claim 9, wherein the modification means comprise a shaft (74) with axis (y2) parallel to a main extension direction of the needle (72) and an arm (76) having a first end mounted pivotally around the shaft (74), the preforming means being fixed to a second end of the arm (76), distinct from the first end, and wherein, during the winding step (101), the conductor wire (8) being wound being in the process of forming a winding layer, the preforming means maintain the conductor wire (8) in contact with a winding layer immediately below the winding layer being formed, or in contact with the branch (12) being wound.

Images