Method for manufacturing a stator for an electric motor and a stator for an electric motor

Abstract

A method of manufacturing a stator for an electric motor having a stator body (10) having a plurality of stator teeth arranged radially about a common central axis (Y) and a plurality of sectors (3) defined between the teeth and into which one or more windings (4) made of conductive wire (14) are at least partially inserted, the method comprising the steps of: The method comprises: providing two jigs (2, 2'), each having an inner periphery defining a circular opening (20', 20") within the jig (2, 2') and a series of teeth (21, 21') projecting into said circular opening (20', 20") towards a common central axis (Y), said series of teeth defining a series of slots (22', 22") therebetween; disposing the two jigs (2, 2') coaxially about a common central axis (Y) and spaced apart along the central axis (Y); winding or inserting a plurality of the windings (4) of the conductive wire (14) having straight wire portions (4a, 4b) extending between the jigs (2, 2') between the teeth (21, 21') of the jigs (2, 2') to form a plurality of windings (4) and occupy a plurality of the slots (22', 22") of both of the jigs (2, 2'); inserting a plurality of first stator sections (6) between the straight wire sections (4a, 4b) from the inside; and inserting a second stator portion (7) complementary to the first stator portion (6) from the outside between the straight wire portions (4a, 4b) to join the first stator portion (6) and the second stator portion (7) to form a stator body (10) including the straight wire portions (4a, 4b) in separate sectors (3) defined between the first stator portion (6) and the second stator portion (7).

Description

[Technical field]

[0001] SUMMARY OF THE DISCLOSURE The present invention is directed to a method of manufacturing a stator for an electric motor, and to an electric motor stator manufactured thereby. [Background technology]

[0002] As is known, the stator of an electric motor is generally cylindrical in shape and comprises a number of fixed poles formed by stator teeth disposed along the inner circumference of the cylinder and projecting towards a common central axis.

[0003] One or more coils of conductive wire, also called windings, are arranged between the stator teeth, or more precisely, in sectors of the spaces between the same stator teeth.

[0004] Stators include concentrated winding, in which conductive wire is wound around each stator tooth, and distributed winding, in which conductive wire is wound around two or more stator teeth. The present invention particularly relates to the manufacture of distributed winding stators.

[0005] In the known art, in the manufacture of distributed winding stators, the cylindrical body of the stator is first manufactured by assembling the teeth, and on the outside of the stator body, one or more windings of conductive wire are inserted into the sectors between the teeth of the already formed cylindrical body.

[0006] According to patent application PCT / IB2021 / 057982 in the name of the applicant, it is known to carry out pressing and / or carburizing steps (in any desired sequence) before inserting the straight wire portions of the winding in the sectors between the teeth of the cylindrical body of the stator to be formed.

[0007] For this reason, it is necessary to provide an opening (slot opening) large enough for inserting a winding between the tooth ends (called "pole pieces" in this technical field) of two adjacent teeth.

[0008] Noise phenomena increase as the distance between the pole pieces increases or as the slot opening increases, especially the torque ripple phenomenon (also known as torque ripple and cogging), which results in reduced performance, increased vibration and noise, and is an improvable aspect in the known technology.

[0009] In this type of stator, it is desirable to increase the packing factor of the sectors, i.e. to be able to insert more conductive wires, or the same number of wires with a larger diameter, in the same sector, since this allows improving the performance of the electric motor. The packing factor is defined as the ratio of the cross-sectional surface occupied by the conductive wires in the stator slots to the total area available in the stator slots (always considered in cross section).

[0010] Furthermore, the above-mentioned known types of stators are limited in that after the winding is inserted into the stator, some of the loops constituting the winding are always positioned towards the centre of the stator, while other loops are always positioned towards the outside of the stator, which increases the leakage current of the motor and thus reduces the efficiency of the motor itself.

[0011] To achieve electric motors that are smaller and lighter than currently available electric motors, it is further desirable to be able to minimize the axial volume of the stator with comparable performance. Summary of the Invention

[0012] SUMMARY OF THE PRESENTLY PREFERRED EMBODIMENTS It is an object of the present invention to provide a method for manufacturing a stator for an electric motor that overcomes the drawbacks and limitations of the known art in one or more of the above mentioned aspects.

[0013] To achieve this objective, the object of the present invention is to implement a method for manufacturing a stator for an electric motor, which allows to obtain a stator for an electric motor which improves the performance of the motor, in particular in terms of efficiency and / or performance and / or vibrations and / or noise.

[0014] A further object of the invention is to implement a method for manufacturing a stator that allows for an improved filling rate of the sectors within the stator.

[0015] A further object of the present invention is to implement a method for manufacturing a stator that allows reducing the torque ripple (torque ripple and cogging) phenomenon.

[0016] Another object of the present invention is to provide a method of manufacturing a stator that is easy to produce and economically advantageous relative to known techniques.

[0017] The objectives set forth above, as well as other objects which will become more apparent hereinafter, are achieved by a method according to claim 1 for manufacturing a stator for an electric motor, the stator comprising a stator body including a plurality of stator teeth arranged radially about a common central axis, the teeth defining sectors between which one or more windings of conductive wire are at least partially inserted.

[0018] In particular, the method includes providing two fixtures, each having an inner periphery defining a circular opening therein, and a series of teeth disposed along the inner periphery and projecting into the circular openings toward a common central axis Y. The teeth define a series of slots therebetween for receiving windings.

[0019] The two jigs are coaxially arranged about a common central axis Y and are spaced apart in height along the central axis Y. The spacing between the jigs on the central axis Y corresponds to the length of the straight portion of the winding and is equal to the height of the coil.

[0020] A number of windings of conductive wire are disposed between the teeth of the fixture, with the conductive wire of each winding occupying a number of the slots of both fixtures, the windings preferably comprising straight wire portions extending between the two fixtures, including straight portions that are pressed and carburized.

[0021] Once the skeleton of the stator has been created, with two fixtures supporting the windings and with straight sections extending parallel to the central axis Y located between the slots of the fixtures, finishing of the stator proceeds by encapsulating the straight sections of the windings as described below.

[0022] Therefore, a plurality of first stator parts are inserted from the inside between the straight wire parts.

[0023] A second stator section, complementary to the first stator section, is inserted from the outside between the straight wire sections, and the first and second stator sections are joined to form a stator body including the straight wire sections in separate sectors defined between the first and second stator sections.

[0024] Whether the first or second stator section is inserted first between the straight sections of windings extending between the fixtures is irrelevant for purposes of the present invention. The method may be carried out by first inserting the first stator section from the inside to the outside, followed by inserting the second stator section from the outside to the inside, or vice versa.

[0025] This causes the straight sections of the winding to be enclosed, eg, welded, between the first and second stator parts, as described below.

[0026] A second aspect of the invention relates to a stator formed directly by the method.

[0027] Simulations by the applicant have shown that a stator obtained by the method described herein has lower production costs, is more efficient and exhibits reduced torque ripple phenomena compared to a stator with the same characteristics obtained by a conventional method of filling the inter-sector teeth. [Brief description of the drawings]

[0028] Further features and advantages will become more apparent from the following non-limiting description of a preferred embodiment of a method for manufacturing a stator, given by way of non-limiting example, with reference to the accompanying drawings, in which: FIG. [Figure 1a] FIG. 1a is a flow diagram showing the main steps of the method according to the invention. [Figure 1] FIG. 1 is a perspective view of two fixtures used in the method according to the invention. [Diagram 2] FIG. 2 is a diagram showing steps of winding a conductor around the jig for winding shown in FIG. 1 in a possible embodiment of the method according to the invention. [Diagram 3] FIG. 3 is a diagram showing steps of winding a conductor around the jig for winding shown in FIG. 1 in a possible embodiment of the method according to the invention. [Figure 4] FIG. 4 is a diagram showing steps of winding a conductor wire on the winding manufacturing jig shown in FIG. 1 in a possible embodiment of the method according to the invention. [Diagram 5] FIG. 5 is a cross-sectional view of FIG. 4 taken along a plane parallel to one of the fixtures. [Figure 6] FIG. 6 shows the completion of the step of inserting the first stator section. [Figure 7] FIG. 7 is a cross-sectional view of FIG. 6 taken along a plane parallel to one of the fixtures. [Figure 8] FIG. 8 shows the step of inserting the second stator section completed to form the stator body. [Figure 9] FIG. 9 is a cross-sectional view of FIG. 8 taken along a plane parallel to one of the fixtures. [Figure 10] FIG. 10 is a side view of a possible embodiment of the winding machine. [Figure 11] FIG. 11 is a detailed plan view of the device shown in FIG. [Figure 12] FIG. 12 is a detailed cross-sectional view of the device shown in FIG. [Figure 13] FIG. 13 is a detailed cross-sectional view of the device shown in FIG. [Figure 14] FIG. 14 is a detailed cross-sectional view of the device shown in FIG. [Figure 15] FIG. 15 is an exploded view of a first embodiment of a winding tool according to the present invention. [Figure 16] FIG. 16 is an exploded view of a first embodiment of a winding tool according to the present invention. [Figure 17] 17 is a perspective view of the winding tool in successive steps. [Figure 18] 18A-18C are perspective views of the winding tool in successive steps. [Figure 19] FIG. 19 is a side view of the winding tool. [Figure 20] FIG. 20 is a cross-sectional view of the winding tool of FIG. 19 taken along a different plane. [Figure 21] FIG. 21 is a cross-sectional view of the winding tool of FIG. 19 taken along a different plane. [Figure 22] FIG. 22 is a cross-sectional view of the winding tool of FIG. 19 taken along a different plane. [Diagram 23] FIG. 23 is a perspective view of the winding produced in the winding creation step of the method. [Figure 24] FIG. 24 is a perspective view of a plurality of windings produced in the winding creation step. [Diagram 25] FIG. 25 is a perspective view of a pressing / carburizing apparatus for performing the pressing and / or carburizing steps of the present method. [Figure 26] FIG. 26 is a vertical view of the apparatus of FIG. 25 at successive times of the pressing and / or carburizing steps. [Figure 27] FIG. 27 is a vertical view of the apparatus of FIG. 25 at successive times of the pressing and / or carburizing steps. [Figure 28] FIG. 28 is a perspective view showing a part of a second possible embodiment of a winding tool according to the invention. [Figure 29] FIG. 29 is a perspective view showing a part of a second possible embodiment of a winding tool according to the invention. [Figure 30a] FIG. 30a shows cross-sectional views of different types of possible coil loops. [Figure 30b]FIG. 30b shows cross-sectional views of different types of possible coil loops. [Figure 30c] FIG. 30c shows cross-sectional views of different types of possible coil loops. [Figure 31a] FIG. 31a shows cross-sections of different types of coil loops according to an optional solution. [Figure 31b] FIG. 31b shows cross-sections of different types of coil loops according to an optional solution. [Figure 31c] FIG. 31c shows cross-sections of different types of coil loops according to an optional solution. [Diagram 32] FIG. 32 is a perspective view showing details of a second possible embodiment of the winding tool. [Diagram 33] FIG. 33 is a front view of the winding tool of FIG. [Diagram 34] FIG. 34 is a side view of the winding tool of FIG. [Diagram 35] FIG. 35 is a plan view of the winding tool of FIG. [Diagram 36] FIG. 36 is a perspective view showing two successive steps of a heat treatment process performed on the winding contained in the winding tool of FIG. [Figure 37] FIG. 37 is a perspective view showing two successive steps of a heat treatment process performed on the winding contained in the winding tool of FIG. [Figure 38] FIG. 38 is a perspective view showing two successive steps of the pressing process performed on the winding contained in the winding tool of FIG. [Figure 39] FIG. 39 is a perspective view showing two successive steps of the pressing process performed on the winding contained in the winding tool of FIG. [Diagram 40] FIG. 40 is a top partial cross-sectional view of FIG. [Diagram 41] FIG. 41 is a perspective view showing a creation sequence of the pitch correction step by the pitch correction device. [Diagram 42] FIG. 42 is a perspective view showing a creation sequence of the pitch correction step by the pitch correction device. [Diagram 43] FIG. 43 is a plan view showing a possible blanking layout for the manufacture of the stator components. [Diagram 44] FIG. 44 is a comparative diagram showing the efficiency versus rotational speed (expressed in revolutions per minute) of a motor equipped with a stator according to the invention, compared with the same motor equipped with a stator obtained with the conventional coil insertion technique. [Diagram 45] FIG. 45 is a comparative diagram of the torque ripple versus rotational speed (expressed in revolutions per minute) of a motor equipped with a stator according to the invention, compared with the same motor equipped with a stator obtained with the conventional coil insertion technique. Detailed Description of the Invention

[0029] In its essential aspects, the method comprises a winding preparation step A, an optional pressing and / or carburizing treatment step B, a step C of placing the winding in a jig, and an assembly step D, as shown in the flow diagram of FIG. 1a.

[0030] With reference to the aforementioned figures, the method is directed to the manufacture of a stator for an electric motor, and in particular a distributed winding stator comprising a stator body 10 having a plurality of stator teeth arranged radially about and projecting towards a common central axis Y. Such teeth define between them a number of sectors 3 (i.e. spaces separating straight portions 4a, 4b of the winding 4) into which one or more windings 4 of a conductive wire 14 are at least partially inserted, as shown in Figures 7 to 9.

[0031] More specifically, as is known, longitudinally substantially straight portions 4a, 4b of the winding 4, i.e. electrically conductive lines 14, hereinafter referred to as "straight portions" 4a, 4b, are housed within the sectors 3.

[0032] The method comprises the following steps, which are described in detail below: arranging two jigs 2, 2' with inner teeth 21, 21' coaxially and spaced apart from each other in the height direction (FIG. 1) (Step A), winding a plurality of conductive wires 14 between the teeth 21, 21' of the jigs 2, 2' to form a plurality of windings 4 (FIGS. 2-4) or placing the windings 4 on a winding tool and positioning them sequentially on the jigs 2, 2' (Step C), and inserting a plurality of first stator parts 6 from the inside and a plurality of second stator parts 7 complementary to the first stator parts 6 from the outside in a desired order to encapsulate the straight parts 4a, 4b and form a completed stator body 10 (FIGS. 5-9) (Step D).

[0033] More specifically, to carry out the method, it is necessary to prepare two fixtures 2, 2' (i.e. elements suitably shaped to act as references and hold the conductive wire 14 in place) as shown in Figure 1. These fixtures 2, 2' are generally circular crown-shaped in plan view, although the shape of the outer shape can vary as required.

[0034] Each of the jigs 2, 2' defines an inner periphery defining a circular opening 20, 20" within the jig 2, 2' itself, and a series of teeth 21, 21' are disposed along the inner periphery so as to project radially towards the central axis Y.

[0035] In other words, the teeth 21, 21' project inwardly of the circular opening 20, 20'' towards the central axis Y and define a series of slots, recesses or grooves 22', 22'' between each of the teeth.

[0036] These slots 22', 22" are in fact configured in shape and position to substantially correspond to the three sectors 3 (i.e. the spaces between the stator teeth which accommodate the conductive wires) of the stator body 10 of the stator to be manufactured.

[0037] In this method, two jigs 2, 2' are positioned coaxially, centered along the same common central axis Y, and spaced apart in the height direction along that central axis Y, in effect like the two bases of an ideal cylinder.

[0038] In this manner, step A is performed in which a plurality of conductive wires 14 are wound between the teeth 21, 21' of the jigs 2, 2' to form a plurality of windings 4 (i.e., coils of the conductive wire 14). The conductive wires 14 are wound such that the conductive wires 14 of each winding 4 occupy a plurality of slots 22', 22" in both the jigs 2, 2'. The winding 4 thus formed has straight portions 4a, 4b of the conductive wire extending parallel to the central axis Y between the two jigs 2, 2' and connecting to non-straight portions 42 at the top and bottom. Therefore, the straight portions 4a, 4b of the conductive wire are arranged in the circumferential direction around the central axis Y, parallel to the axis Y, at a regular pitch corresponding to the pitch of the slots 22', 22".

[0039] In this step, each winding 4 has first and second straight portions 4a, 4b that are parallel to each other and connected by a non-straight portion 42, and the first and second straight portions 4a, 4b are preferably inserted into different grooves 22', 22" of each jig 2, 2', respectively.

[0040] Each winding 4 is preferably formed by a number of conductive wires 14 .

[0041] Typically, each coil is made up of one, two or more parallel wires 14, and a winding 4 may have, for example, 100 loops of only a single wire 14, 50 loops of two parallel wires, or 10 loops of ten parallel wires 14, etc.

[0042] It will be apparent that the number of wires 14 wound in parallel in each loop, the number of levels, and the number of wires 14 per level can be varied and selected depending on the needs of the project.

[0043] More specifically, in general: Each loop is formed of 1 layer, 2 layers, or n layers. Each layer is formed with 1, 2, or n wires 14 .

[0044] The number of wires in one layer may be the same as or different from the number of wires in a successive layer.

[0045] As shown in FIGS. 12-22, in step A of creating the windings 4, instead of winding the conductive wire 14 directly around the jig 2, 2′, one or more conductive wires 14 may be wound around a winding tool 20X to form at least one winding 4 having at least one straight portion 4a, 4b, each straight portion 4a, 4b being made up of a plurality of individual straight portions of wire that are inserted into one of the slots 22′, 22″ as described above.

[0046] In this case, step A is followed by a step C of accommodating the winding 4 as diagrammatically shown in FIG. 1a, in which the straight sections 4a, 4b of the winding 4 are inserted into the slots 22′, 22″ after removing the winding 4 from the winding tool 20X.

[0047] 12-22 show in detail the winding tool 20X configured for producing the winding 4. FIG.

[0048] It will be apparent that the number of conductive wires 14 (and wire tensioning devices 203) wound in parallel in each loop, the number of levels (and ducts 251 within the wire guide tube 204), and the number of conductive wires 14 per level can be varied and selected depending on the project requirements.

[0049] Depending on the implementation choice, the winding tool 20X may have one winding 4 (as in FIG. 23) or may have multiple windings 4 (as in FIG. 24).

[0050] The windings may be made of one, two or more parallel wires; the winding 4 may, for example, have 100 loops made of only a single wire 14, 50 loops made of two parallel wires, or 10 loops made of ten parallel wires 14.

[0051] The winding tool 20X preferably includes a plurality of movable walls 22 disposed between a fixed wall 23 and a removable disassembly wall 24.

[0052] The fixed wall 23 is configured to be operatively coupled to the take-up spindle 244 so as to drive the rotation of the movable wall 22, and for this purpose optionally comprises a sleeve for hooking onto the spindle 25.

[0053] The removable disassembly wall 24 can be removed from the fixed wall 23 to release the movable wall 22 and allow displacement of the wound winding 4 .

[0054] The movable wall 22 defines one or more winding chambers within which the conductive wire 14 is wound to form the windings 4 .

[0055] More specifically, in the preferred embodiment shown, the fixed wall 23 further comprises a wire clamp 26 configured to clamp the wires 14 (already arranged in the appropriate configuration) that are to be incorporated into the winding.

[0056] The fixed wall 23 further comprises a centering pin 27 for centering the movable walls 22, which usefully protrudes towards the removable wall 24 and engages with a tunnel formed by a central hole 28 located in the center of each movable wall 22.

[0057] The end of the centering pin 27 is provided with a hook end 271 for hooking the hook wall 24 to the removable wall 24 .

[0058] Preferably, the hanging wall 23 is provided with a number of (four in the illustrated example) axial positioning pins 231 protruding towards the removable wall 24, which occupy positioning holes 29 in the movable wall 22 to correctly axially position the movable wall 22 during winding and to ensure the correct dimensions of the winding chamber.

[0059] As can be seen from the figure, the axial positioning pin 231 is formed by a number of longitudinal portions having different diameters and decreasing towards the removable wall 24, and the positioning holes 29 have different diameters for each movable wall 22 and decrease towards the removable wall 24, so that each movable wall 22 is locked to its respective longitudinal portion of the axial positioning pin 231.

[0060] Thus, the movable walls 22 maintain their axial dimension (determined by the thickness of the walls 22 and the distance between the walls 22) during the winding step (creating the winding 4), while being movable toward one another by the thrust during the pressing step, as described below. Such axial dimension is conveniently maintained by a mechanical reference element 291, which ensures the repeatability of the process and the consistency of the final dimensions of the pressed winding (i.e. the coil 4). In practice, the winding tool 20X is configured such that the movable walls 22 are movable toward one another under the action of pressure up to a distance defined by the mechanical reference element 291, which serves as a limit abutment.

[0061] The number of movable walls 22 of the winding tool 20X is determined by the number of windings 4 made in series (equal to the number of windings per electrode and per sector 3) + 1, i.e. Np = nm + 1, where Np is the number of movable walls 22 and nm is the number of windings. In practice, nm windings are windings that are part of individual electrodes.

[0062] The movable wall 22 has a generally rectangular shape in both vertical and horizontal cross sections when viewed from above. The movable wall 22 preferably includes an operation seat 249 on a side surface that protrudes outward from the winding tool 20X.

[0063] In preferred embodiments, each movable wall 22 is formed by a central support 221 and two winding sides 222 fixed on two sides of the central support 221. In this case, the handling seat 249 is provided on the winding sides 222. In practice, in these embodiments, the winding chamber is defined between the winding sides 222.

[0064] Insulation is sandwiched between the central support 221 and the winding sides 222 to limit heat loss during the hot carburization process described below.

[0065] The removable disassembly wall 24 is removable in the sense that it can be separated from the fixed wall to allow the movable wall 22 to be pulled out.

[0066] In a preferred embodiment, the removable wall 24 also includes wire clamps 261 configured to clamp each of the wires 14 emerging from the coil, thereby maintaining the wires 14 in the proper alignment.

[0067] The removable wall 24 is then provided with a coupling device 241 for coupling directly or indirectly to the fixed wall 23, for example by hooking a hook end 271 of the centering pin 27 of the fixed wall 23 thereon.

[0068] The removable wall 24 preferably further comprises a gripping element 242 configured to be grasped or hooked to permit movement thereof.

[0069] In a preferred embodiment, the winding tool 20X comprises a number of angle elements 245 coupled to the removable wall 24 and slidable on respective appropriately inclined guides 246. Such guides 246 extend from the removable wall towards, and preferably up to, the fixed wall 23. The angle elements serve as abutments for the wire 14 during winding.

[0070] Preferably, there are at least four corner elements 245, one located at each corner.

[0071] This detail along with the guides 246 allows the corner elements 245 to slide toward the center of the winding tool 20X (as shown in Figures 9 and 10) as the removable wall 24 is pulled from the hook wall to loosen the wire 14 forming the winding 4, thereby allowing the winding 4 to be removed without the wire 14 being rubbed and damaged.

[0072] In a possible method, during winding creation step A, a supplementary conductive wire having a cross section smaller than the cross section of the main conductive wire is added to a conductive wire 14, which can be defined as a main conductive wire, the supplementary conductive wire occupying the free space between adjacent main conductive wires 14.

[0073] Preferably, the method further comprises the step of insulating the conductive wires 14. The electrically insulating layer comprises: Whenever provided (see below), they are provided at least on the straight sections 4a, 4b of the winding 4 after the pressing and / or carburizing step B has been carried out; or The winding 4 is provided between the first stator part 6 and the second stator part 7 before being inserted between the straight parts 4a, 4b of the winding 4 and encapsulated.

[0074] In carrying out step A of creating the windings 4, it is preferred that a series of windings 4 are created on the winding tool 20X by ensuring that straight portions 4a, 4b of the windings 4 are spaced from consecutive straight portions 4a, 4b of the windings 4 according to a predetermined pitch distance.

[0075] The method, in this situation, comprises the steps of: before accommodating the winding 4 between the slots 22', 22" of the fixtures 2, 2': a pitch compensation device (see Figs. 41 and 42) for example comprising pliers movable by an actuator and adapted to compensate the pitch distance between the straight portions 4a, 4b of the different windings, by mechanical interaction of the series of windings 4 with the pitch compensation device, if necessary, corresponding to the pitch between the slots 22', 22" of the fixtures 2, 2'; The winding 4 is displaced by pliers so as to keep the pitch distance between the straight portions 4a and 4b constant. Using pliers, the straight sections 4a, 4b are inserted between the slots 22', 22'' of the fixtures 2, 2'.

[0076] Whenever the winding 4 is formed on the winding tool 20X, step A is followed by a step C of accommodating the straight portions 4a, 4b of the winding in the slots 22', 22" of the jig 2, 2'. This step is carried out by means of pliers and an actuator which removes the winding 4 from the winding tool and inserts the straight portions 4a, 4b into the slots 22', 22" of the jig 2, 2' without changing the pitch between the straight portions 4a, 4b.

[0077] In Fig. 10, a possible embodiment of a winding machine 200 is shown in which the conductive wire 14 is wound on a winding tool 20X shown in Figs. 12 to 22. The winding machine 200 comprises a support structure 201, a plurality of wire tensioning devices 203 (of a known type) for tensioning the conductive wire 14 being wound; a wire guide device 206 having a wire guide tube 204 and movable along a guide 205 (preferably made of a bar) for guiding the wire; 2, and a winding spindle 244 which is adapted to be rotated by the motor 214 and rotate the winding tool 20X as described above, and which in effect is coupled to a sleeve for hooking onto the spindle 25.

[0078] Such a winding machine 200 can be configured into an operable winding structure, in which the conductive wire 14 to be wound is fed under tension from a wire tensioning device 203 toward a wire guiding device 206, which guides the conductive wire 14 toward a rotating winding tool 20X.

[0079] Optionally, the winding machine 200 further comprises a tailstock 215 disposed coaxially with the main shaft 244 and configured to be coupled to the removable wall 24 of the winding tool 20X.

[0080] FIG. 11 shows in detail the wire guiding device 206, which comprises a base 217 to which a wire directing element 216 (preferably a pair of rotating members) is fixed, and which guides the conductive wire 14 into a wire guide tube 204 located at the end of the base 217 facing the winding tool 20X.

[0081] 12 and 13 show details of a reel member 218 that is provided in the winding machine 200 and is preferably arranged coaxially with the spindle 244, and that aligns the wire 14 fed out of the wire guide tube 204 into a loop before being wound onto the winding tool 20X.

[0082] In Fig. 14, a cross section of the wire guide tube 204 is shown, which is made up of several sectors separately defining several ducts 251 for the conductive wires 14, such that the conductive wires 14 intended for the formation of a level of loops are held in place in each duct 251. In the example shown, there are three ducts 251, the wires are arranged on three levels, with a 5-4-5 sequence (5 wires on the first level, 4 wires on the second level, 5 wires on the third level), for a total of 14 wires arranged in parallel for each loop, each conductive wire 14 being fed and managed by one of the 14 wire tensioning devices 203 shown in Fig. 10.

[0083] After the production of the winding 4 in step A and before step C, a pressing and / or carburizing step B may optionally be carried out as shown diagrammatically in Fig. 1a, in which the straight wire portions 4a, 4b of the winding 4 are pressed and / or thermally carburized to compact the individual straight wire portions 4a, 4b. This is a step in which at least one of the straight portions 4a, 4b of the winding 4 is subjected to a pressing step, a thermally carburizing step or both a pressing step and a thermally carburizing step, in any desired sequence or simultaneously, thereby compacting the individual straight wire portions that were systematically arranged in step A of producing the winding 4 according to their arrangement.

[0084] Advantageously, the straight sections of the conductive wire 14 of the pressed and carburized windings 4 remain together and do not separate or shift relative to one another. This detail allows the coil to be formed and maintained in the best possible geometric configuration for each dimension of the slots 22', 22" to be filled, in order to maximize the fill factor and to prevent fraying during movement of the windings 4.

[0085] Step B preferably lasts from 15 seconds to 2 minutes.

[0086] In a possible method, in the pressing and / or carburizing step B, the thermal carburizing is performed by inserting one or more heating elements between the straight sections of the windings 4 and heating them to a predetermined carburizing temperature (typically in the range of 170°C to 210°C).

[0087] In a possible method, in the carburizing and / or pressing step B, the straight portions 4a, 4b are pressed by a pressing device which is inserted between the straight portions 4a, 4b of the winding 4 while the winding 4 is housed in a winding tool after removing the heating element.

[0088] 25-27 show an example of a pressing and / or carburizing apparatus 300 that can be used to achieve a winding 4 having the characteristics described above.

[0089] In the illustrated example, the apparatus 300 performs both pressing and carburizing and comprises a receiving seat 301 configured to receive the winding tool 20X and one or more pressing elements 30 configured to apply pressure to at least one straight portion 4a, 4b of the winding 4 wound on the winding tool 20X.

[0090] Two pressing elements 30 are preferably provided, arranged coaxially on opposite sides of the receiving seat, which apply pressure towards each other, preferably horizontally, so as to press against two opposing straight sections 4a, 4b of each winding, respectively.

[0091] The pressing element 30 comprises at least one heating device 31 (preferably consisting of one or more inductors) configured to heat the straight portions 4a, 4b before, during or after pressing so as to perform a thermal carburization treatment while the winding 4 is being wound on the winding tool 20X.

[0092] The pressing element 30 is actuated by a pressure movement system 304, which in the embodiment shown consists of a piston and a spring coaxial with the piston.

[0093] In some embodiments, the heating device 31 is included in or connected to the pressing element 30, more specifically, it is arranged in a head 32 which constitutes the end of the pressing element 30 itself and which is in contact with the straight sections 4a, 4b during pressing.

[0094] Advantageously, the number of heating devices 31 is equal to the number of movable walls 2 .

[0095] Optionally, the pressing and / or carburizing treatment apparatus 300 is preferably equipped with a heat probe 34 and / or a pyrometer 35 coupled to the pressing element 30, thereby allowing feedback control of the carburizing process by a control system controlling the heating element 31.

[0096] More specifically, the pressing and / or carburizing treatment device 300 is provided with a fixed abutment 311 against which the winding tool 20X rests on the receiving seat 301. Such a fixed abutment 311 has an inclined surface made of a heat insulating material against which the winding tool 20X rests, thereby limiting heat loss.

[0097] The pressing and / or carburizing treatment device 300 preferably comprises a press head 302 moving vertically relative to the pressing element 30 (vertical 302 in the illustrated example) and compressing the winding tool (and the winding 4) vertically relative to the pressing element 30, thereby bringing the movable walls 22 closer together and further compacting the straight sections 4a, 4b of the winding 4 and determining its thickness with reference to a mechanical reference element 291 acting as a limit abutment. In practice, the press head 320 compresses the winding tool 20X (and the winding 4) against a fixed abutment 311.

[0098] Therefore, in a preferred embodiment, the straight portions 4a, 4b of each winding 4 are subjected to two pressures in mutually perpendicular directions, as shown in Figure 27. Advantageously, only the straight portions 4a, 4b of the winding 4 are pressed and subjected to heat treatment, while the non-straight portions (i.e. the mainly curved portions of the winding 4 connecting the straight portions 4a, 4b and forming the tips of the windings 4) are not treated so as to make them easily shapingable in subsequent processes.

[0099] Once a predetermined carburizing temperature has been reached, which depends on the characteristics of the wire 14 used, the press element 30, possibly a vertical press 320, maintains the pressure for the time required for cooling, with the aid of a cooling device (not shown) that stabilizes the straight sections 4a, 4b in their final dimensions.

[0100] In the example shown, the pressure ranges from 140 to 300 bar and the temperature reached by the heating element 31 ranges from 170° to 210° C. The duration of step B is between 15 seconds and 2 minutes.

[0101] Optionally, the pressing and / or carburizing treatment device 300 comprises a loading slide 330 configured to move the winding tool 20X with the winding 4 into the receiving seat 301 and place it on the fixed abutment 311. As shown in Fig. 25, the loading slide comprises a platform slidable along a horizontal track 331 and configured to be vertically movable and configured to lift the winding tool 20X.

[0102] Advantageously, the pressing and / or carburizing step B compacts the windings by making the dimensions of the straight sections 4a, 4b of the winding 4 reproducible and maximizing the packing factor. Moreover, the straight sections 4a, 4b thus treated are compacted between themselves so that the arrangement of the wire 14 does not change during the entire process. The wires are arranged and held in an orderly and reproducible matrix and are not grouped in a random order, preserving the order of the initial winding.

[0103] In the example given, the straight sections 4a, 4b of the winding 4 are first pressed and then carburized, but in general the method can be carried out by pressing or carburizing or both in the order given, or in the reverse order, or by pressing and carburizing simultaneously.

[0104] After the pressing and / or carburizing step B, the winding 4 is cooled and the straight sections 4a, 4b are solidified, and the winding itself is removed from the winding tool 20X. The coupling device 241 is (pneumatically) unlocked by supporting the winding tool 20X by a sleeve for hooking onto the spindle 25 and / or the gripping element 242.

[0105] The wire clamps 26, 261 are then opened, for example by two external control devices, to release the wire 14 entering and leaving the coil. At this point, the manipulators (not shown) which guide the removable wall 24 of the winding tool start to move axially away from the fixed wall 23. In the first step of this movement, the angular elements 245 sliding on their respective guides 246 start to move towards the centre of the winding tool 20X so as to loosen the wire and allow removal of the winding.

[0106] Thus, the manipulator guiding the removable wall 24 continues to move axially away from the fixed wall 23 until the second manipulator moves the movable wall 22 by the operating seat 249 until it is pulled out from the fixed wall 24 (pulled out from the pins 27, 231).

[0107] At this point, the winding 4 or windings 4 are removed from the winding tool 20X, for example by a transfer system.

[0108] In an alternative embodiment of the winding machine 200 shown in Figures 28 and 29, including a further embodiment of the winding tool 20X', instead of the wire guide device 206 with a single wire guide tube 204 of Figure 206, a wire orientation device 150 is used, which makes it possible to automatically manage the distance between the various levels of the wire 14 fed by the controlled axis.

[0109] The wire directing device 150 includes an axial guide 151 along which a number of wire guide tubes 152 slide in a controlled, independent manner relative to one another.

[0110] The axis guide 151 slides along the guide 153 such that the wire guide tube 152 is movable along at least two axes.

[0111] Each wire guide tube 152 intersects a layer of wires 14 and actually directs the wires 14 .

[0112] During the various winding steps, the wire guide tubes 152 can be moved closer to each other until the various levels of wire touch, or can be moved away from each other so that each layer enters the coil independently and at a different time than the other layers.

[0113] This allows each layer to be stacked independently on the winding tool 20X' without interfering with the other layers.

[0114] If necessary, the wire guide tubes 152 are moved in close proximity to one another to facilitate manipulation provided that the wires 14 are all in close proximity to one another.

[0115] Optionally, in this embodiment, the winding tool 20X' is rotated by a winding spindle 244' integrated into a motor assembly 157 fixed to a carriage 158 movable along a track 159 (guide, rail, etc.).

[0116] 30a, 30b and 30c illustrate different loops obtained with both the first and second embodiments of the winding tool described herein; FIG. 30a shows loops S1, S2 formed from two layers, a first layer of five wires and a second layer of four wires; FIG. 30b shows loops S1′ and S2′, each made of two layers of five wires; FIG. 30C shows loops S1'', S2'' formed from three layers: a first layer of five wires, a second layer of four wires, and a third layer of five wires.

[0117] As can be seen from the previous figures, round wires tend to leave free space, and to overcome this problem any of the solutions shown in Figures 31a, 31b, 31c may be adopted.

[0118] According to this optional and advantageous solution, in the winding step A, and more precisely during winding, the free space free of contact of the wire 14 with the larger cross section (i.e. the free space between the wires 14 with the larger cross section) is occupied by a complementary conductive wire 141 with a smaller cross section and is arranged in each loop S1, S2. In this way, during the winding step, each loop S1, S2 consists of layers formed by alternating wires of different cross sections, which when wound can achieve a higher filling factor.

[0119] 32 to 40 show a second embodiment of a winding tool 20X', in which one or more windings 4 are formed.

[0120] Specifically, the winding tool 20X' comprises a support frame 21x, 22x supporting a series of four angular elements 23x, each of which is arranged along an edge of a substantially ideal parallelepiped. Each of the angular elements 23x is spaced apart from one another to define a series of winding chambers 24' (FIGS. 34 and 35) that accommodate the conductive wire forming the winding 14. This configuration of the winding tool 20X' allows a desired number of angular elements 23x to be attached to each guide 231 at a desired pitch, allowing the winding 4 to be manufactured having a desired number of straight portions 4a, 4b, the straight portions 4a, 4b being spaced apart by a desired pitch distance.

[0121] The heating device 30, as shown in Figures 36 and 37, comprises one or more heating elements 31, preferably performing induction heating. These heating elements 31 are shaped and arranged to be inserted between, in contact with or adjacent to the straight portions 4a, 4b of the winding 4. The space between the straight portions 4a, 4b allows this operation to be performed while the winding 4 is housed in the winding tool 20X'.

[0122] These heating elements 31 therefore have a longitudinal extent substantially equivalent to the straight sections 4a, 4b which are heated.

[0123] In the illustrated embodiment, the heating elements 31 are generally comb-shaped with parallel elements.

[0124] In practice, the heating element 31 is inserted between the straight sections 4a, 4b of the windings and heated to the carburizing temperature.

[0125] This allows time to remove the heating element 31 and insert in its place a pressing device 300 which utilizes the thermal inertia of the material to press the coil.

[0126] In the embodiment shown in Figures 38 and 39, a pressing device 300 comprises a plate 301 associated with a series of inclined surfaces 303 configured to contact the straight sections 4a, 4b to be pressed.

[0127] Advantageously, the plate 301 is inserted or in some way mechanically coupled to a complementary counter-plate 302 arranged on the opposite side of the straight sections 4a, 4b, which complementary counter-plate 302 actually functions as an abutment element.

[0128] Plate 301 is pressed against counter-plate 302 by a thrust device (not shown). The inclined surfaces 303 are configured such that plate 301 moves towards counter-plate 302, thereby compacting the straight sections 4a, 4b of the windings by direct mechanical interaction.

[0129] Thus, the straight sections 4a, 4b of the coil are compacted to the desired dimensions using the force of the thrust device and the appropriately shaped ramps 303.

[0130] These carburizing and pressing operations can be performed alternately or simultaneously on both sides of the winding tool 20X' depending on the cycle time required in factory manufacturing.

[0131] Advantageously, only the straight portions 4a, 4b of the winding 4 are pressed and / or heat treated, while the non-straight portions (i.e. the mainly curved portions of the winding 4 connecting the straight portions 4a, 4b and forming the tips of the winding 4) are not treated so as to make them easily shapable in subsequent processes.

[0132] After an optional pressing and / or carburizing step B, the winding 4 is cooled and the straight portions 4a, 4b are solidified, and the winding 4 can be removed from the winding tool 20X, 20X'.

[0133] Optionally, as shown in Figures 41 and 42, when a series of multiple windings 4 are made on the same winding tool 20X, 20X' in the winding making step, a step of correcting the pitch between the windings on the jig 2, 2' is performed prior to the accommodation step so that the straight portions 4a, 4b of the series of multiple windings 4 are spaced a predetermined pitch distance from the straight portions of adjacent windings 4. In this process, a series of windings 4 are taken out and taken into a pitch compensation device 50, the pitch compensation device 50 being adapted to compensate for the pitch distance between the straight sections 4a, 4b of the different windings 4, for the purpose of mechanically interacting with the pitch compensation device 50, The winding 4 is displaced by the pliers 51 so that the pitch distance between the straight portions 4a, 4b of the winding 4 is maintained.

[0134] More specifically, the pitch correction device 50 consists of a series of parallel longitudinal seats 55 inside which the straight sections 4a, 4b of the windings defined by the insides of parallel longitudinal blocks 56 are inserted.

[0135] When the straight sections 4a, 4b are inserted into the longitudinal seats 55, the distance between them, i.e. the pitch distance between the straight sections 4a, 4b, can be adjusted by changing the spacing of the longitudinal blocks 56 by means of adjustment elements 58 (e.g. screws, etc.).

[0136] Additional adjustment elements 57 (eg screws) are also provided for tightening the slits and fixing the straight sections 4a, 4b when making the adjustment.

[0137] If necessary, insulating paper 59 may be introduced to protect the same winding 4 from damage in the stator 1, preferably around the straight sections 4a, 4b, during the pitch correction process.

[0138] At this point, the winding 4 is ready to be placed on the jigs 2, 2' by a moving device (not shown) comprising the aforementioned pliers 51 and further known devices (e.g. arms, kinematic chains, etc.) selected according to the requirements, as described above and shown in Figures 2 to 5.

[0139] As shown in Figures 6 to 9, the method according to the present invention provides an assembly step D in which multiple first stator sections 6 are inserted between the straight wire sections 4a, 4b from the inside (i.e., from the central axis Y toward the outside).

[0140] In a preferred embodiment, the first stator section 6 includes an enlarged end 61 that, after insertion, resides within the stator body 10 between the straight wire sections 4 a, 4 b and the central axis Y. The junction of the enlarged end 61 defines the inner cylindrical surface of the stator 10.

[0141] In effect, these enlarged ends form the "pole pieces" of the stator, as shown in FIG.

[0142] The first stator section 6 has a radial extent section 62 which is interposed between the straight wire sections 4a, 4b.

[0143] After (or generally before) inserting the first stator portion 6, a plurality of second stator portions 7 complementary to the first stator portion 6 are inserted between the straight wire portions 4a, 4b from the outside (i.e. in the direction of the central axis Y).

[0144] Preferably, the second stator section 7 is generally wedge-shaped and, more particularly, consists of an enlarged base section 71 which remains outside the straight wire sections 4a, 4b after insertion and contributes to forming the cylindrical outer surface of the stator body 10.

[0145] The first and second portions 6, 7 are interleaved with each other, with each second portion 7 mating at least partially with an adjacent first portion 6, and by joining the first and second stator portions 6, 7 a single stator body 10 is formed, with the straight wire portions 4a, 4b being contained within separate sectors 3 defined between said first and second stator portions 6, 7 (as shown in Figures 8 and 9). In effect, the first and second stator portions 6, 7 form stator teeth in the completed stator body 10.

[0146] Although it is preferred to insert all the first sections 6 first, followed by all the second sections 7, the stator sections 6, 7 may be inserted in any order based on design decisions, either one at a time, all the first sectors 6 simultaneously followed by all the second sectors (or vice versa), or alternately.

[0147] The insertion of the stator parts 6, 7 is carried out by means of a suitable industrial manipulator.

[0148] The shape of the stator portions 6, 7 is not limiting and the shapes shown in the figures are merely exemplary in nature. Typically the shape is wedge-shaped, but the corners and aspect ratios may vary between different embodiments depending on requirements.

[0149] At this point, the stator body 10 can be sent to a series of known subsequent steps, including pressing and welding the stator body 10, inserting the stator body 10 directly into the stator case, restraining the winding heads (non-straight portions 41, 42 of the wires 14 emerging from the sectors 3), shaping and / or pressing them, impregnating the stator body, etc.

[0150] The outer diameter of the stator body 10 can be provided with specific templates as required, such as cavities with undercuts or roughly semicircular niches.

[0151] The fixtures 2, 2' are preferably removed before subsequent steps are performed.

[0152] In a first particular embodiment, after the stator parts 6, 7 have been inserted, they are fixed to one another by a welding process, preferably by laser.

[0153] In an alternative embodiment, the stator parts 6, 7 are mechanically locked in place by inserting and joining an outer ring.

[0154] It should be noted that the inner enlarged ends ("pole pieces") of the teeth 61 comprising the first stator portion 6 can be moved closer together to a minimum desired distance so as to minimize noise phenomena, particularly torque ripple and efficiency losses.

[0155] Therefore, the total number of sectors 3 to be assembled can be advantageously reduced.

[0156] Figure 43 shows a possible blanking structure for the manufacture of the stator sections 6, 7. Each stator section 6, 7 is in fact made by stacking an appropriate number of laminations 6', 7' until the desired stator height is reached.

[0157] The blanking structure shown in Figure 43 allows for the minimization of processing waste. This can be easily understood by comparing Figure 43 with a possible mold for the entire stator of circular shape. In this case, the excess material along the outer edges (and often in the middle as well) is discarded.

[0158] Furthermore, a machine constructed to blank the entire circular stator would have to be quite large to perform the operation "at once." On the other hand, the simplicity of the blanking layout in Figure 43 implies that the size of the blanking machine used would be small.

[0159] Both factors, namely minimization of waste and compactness of the blanking machine, lead to an optimization of the total production costs.

[0160] Thus, a first advantage of the method according to the invention is that it is easy to produce and economically competitive with known techniques.

[0161] A further advantage of the method according to the invention is that it improves the filling factor of the sectors inside the stator.

[0162] Applicants have calculated that, all other factors being equal, the method of the present invention may result in a percentage increase in fill factor of between 15% and 30%.

[0163] As a result, electric motors manufactured using stators obtained directly by the method described herein can achieve superior performance, especially in terms of efficiency, vibration and noise, compared to motors manufactured using conventional stators, all other things being equal.

[0164] Table 1 below is the result of simulations carried out by the Applicant, calculating the efficiency of two motors with comparable characteristics, one incorporating a stator obtained directly by the method described herein, called DHD, and the other incorporating a stator obtained by the conventional method of inserting windings of conductive wire, the motor speeds being in the range of 0 to 10,000 revolutions per minute.

[0165] [Table 1]

[0166] Table 1 shows that at three representative values ​​of the motor's revolutions per minute (RPM), namely 3250 RPM, 7000 RPM and 10000 RPM, taking into account uncertainties between -0.7% and +0.7%, the DHD motor offers significantly higher efficiency.

[0167] In fact, at 3250 RPM the efficiency of the DHD motor exceeds 0.91%, at 7000 RPM it exceeds 1.48%, and at 1000 RPM it exceeds 2.11%. The information contained in Table 1 is plotted in FIG.

[0168] A further advantage of the method according to the invention is the reduction of the torque ripple (torque ripple and cogging) phenomenon in the stator. Table 2 below shows the results of simulations carried out by the Applicant, calculating the torque ripple of two motors with comparable characteristics, one incorporating a stator obtained directly by the method described herein, called DHD, and the other incorporating a stator obtained by the conventional method of inserting windings of conductive wire, with motor speeds in the range of 0 to 10000 revolutions per minute.

[0169] [Table 2]

[0170] Table 2 shows that the torque ripple of the DHD motor is significantly smaller at two representative values ​​of the motor's revolutions per minute (RPM), i.e., 3250 RPM and 10000 RPM, taking into account the uncertainty between -6% and +6%.

[0171] In fact, at 3250 RPM, the torque ripple of the DHD motor measured in Nm is less than a percentage value equal to 8.36%, and at 1000 RPM, the torque ripple of the DHD motor is less than a percentage value equal to 18.49%.

[0172] The information contained in Table 2 is presented in the graph of FIG.

Claims

1. 1. A method of manufacturing a stator for an electric motor having a stator body (10) having a plurality of stator teeth arranged radially about a common central axis (Y) and sectors (3) defined between said teeth and into which one or more windings (4) of conductive wire (14) are at least partially inserted, comprising: The method comprises: providing two jigs (2, 2'), each having within the jig (2, 2') an inner periphery defining a circular opening (20', 20") and a series of teeth (21, 21') disposed along the inner periphery and projecting into said circular opening (20', 20") towards a common central axis (Y), said series of teeth (21, 21') defining a series of slots (22', 22") therebetween; disposing the two jigs (2, 2') coaxially about the common central axis (Y) and spaced apart along the central axis (Y); placing the windings (4) of the conductive wire (14), the windings (4) having straight wire portions (4a, 4b) extending between the fixtures (2, 2'), between the teeth (21, 21') of the fixture (2, 2') so as to occupy both of the slots (22', 22") of the fixture (2, 2'); inserting a plurality of first stator sections (6) between the straight wire sections (4a, 4b) from the inside; and inserting a second stator part (7) complementary to the first stator part (6) from the outside between the straight wire parts (4a, 4b) to join the first stator part (6) and the second stator part (7) to form a stator body (10) comprising the straight wire parts (4a, 4b) in separate sectors (3) defined between the first stator part (6) and the second stator part (7).

2. 2. The method according to claim 1, characterized in that the first stator section (6) has an enlarged end (61) which after insertion remains between the straight wire sections (4a, 4b) inside the stator body (10) and the central axis (Y), and a radial extent section (62) which is inserted between the straight wire sections (4a, 4b).

3. 3. The method of claim 2, characterized in that the enlarged ends (61) of the first stator portion (6) together define an inner cylindrical surface of the stator (10).

4. 3. The method according to claim 1 or 2, characterized in that the second stator part (7) is generally wedge-shaped and has an enlarged base (71) which remains outside the straight wire parts (4a, 4b) after insertion and contributes to forming the cylindrical outer surface of the stator body (10).

5. 10. A method according to one or more of the preceding claims, characterized in that the tool (2, 2') is substantially circular crown-shaped in plan view.

6. A method according to one or more of the preceding claims, comprising: A method according to claim 1, characterised in that said stator parts (6, 7) are fixed to one another by a welding process, preferably by laser.

7. A method according to one or more of the preceding claims, comprising: A method according to claim 1, characterized in that an outer ring is used to mechanically lock the stator parts (6, 7).

8. A method according to one or more of the preceding claims, characterized in that it comprises a step of pressing and / or carburizing the straight wire portions (4a, 4b) of the windings (4) before placing them in the fixture (2, 2') or before inserting them into a stator part (6, 7).

9. 9. A method according to claim 8, characterized in that the pressing and the carburizing of the straight wire sections (4a, 4b) are carried out in any desired order or simultaneously.

10. A method according to one or more of the preceding claims, characterized in that the winding (4) is produced on a winding tool (20X, 20X') or directly on the jig (2, 2') so that it can be sequentially removed and placed on the jig (2, 2').

11. A stator (10) for an electric motor, obtained directly by the method according to any one of the preceding claims 1 to 10.

12. A stator (10) for an electric motor, comprising: a body extending about a central axis (Y); and a plurality of windings (4) made of conductive wire (14), each having at least one straight wire portion (4a, 4b), the straight wire portion (4a, 4b) being arranged parallel to the central axis (Y) and distributed at a constant pitch in a circumferential direction of the central axis (Y), the body being inserted between the straight wire portions (4a, 4b) and having a plurality of windings (4) protruding in a radial direction opposite to the central axis (Y). A stator (10) for an electric motor comprising a first stator part (6) and a plurality of second stator parts (7) complementary to the first stator part (6), the second stator parts (7) being inserted between the straight wire parts (4a, 4b) and between the first stator part (6) and projecting radially towards the central axis (Y), characterized in that the straight wire parts (4a, 4b) are enclosed between the first stator part (6) and the second stator part (7).

13. 13. The stator (10) according to claim 12, characterized in that the first stator part (6) comprises an enlarged end (61) arranged on the inner circumference of the stator body (10) and a wedge-shaped radial extent part (62) inserted into the straight wire parts (4a, 4b).

14. 14. The stator (10) according to claim 12 or 13, characterized in that the second stator part (7) comprises an enlarged base (71) arranged on the outer periphery of the stator body and a wedge-shaped part of radial extent interposed between the straight wire parts (4a, 4b) and the first stator part (6).

15. The stator (10) according to any one of claims 12 to 14, characterized in that the first stator part (6) is welded to the second stator part (7).

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