Sheet-metal core for a rotor or stator of an electric machine

Abstract

The invention relates to a sheet-metal core (10) for a rotor or stator of an electric machine, the core (10) consisting of a sheet-metal strip wound in a spiral in successive turns about an axis X comprising alternating tabs and notches, in particular with increasing widths as the winding is carried out, a superposition of the tabs and the notches respectively defining, in the core, teeth (20) and tooth gaps (22), wherein at least one projection (54) extends from at least one edge (58) of at least one of the teeth (20).

Description

SHEET METAL CORE FOR AN ELECTRIC MACHINE ROTOR OR STATOR Technical field of the invention

[0001] The invention relates to a sheet metal core for a rotor or stator of an electric machine, in particular for an electric vehicle motor. Technical background

[0002] One method for manufacturing a rotor or stator core for an electric machine involves spirally winding a strip of sheet metal around an X-axis, this strip having alternating tabs and slots of increasing width as the winding progresses. The overlapping of these tabs and slots defines teeth and gaps within the core.

[0003] Thus, a core with multiple teeth, capable of receiving a winding to form the poles of the rotor or stator in question, can be formed from a single strip of sheet metal. Winding the strip of sheet metal also allows the core to be constructed as a stack of thin layers, thereby reducing induced currents, also known as eddy currents.

[0004] For reliability reasons, the winding is not done directly on the core. Preferably, each tooth receives a coil, made of an insulating material, which has a through-hole with a profile substantially complementary to a tooth and an external groove for receiving the winding wire. Each coil is fitted onto the corresponding tooth.

[0005] However, it was noted that the fitting of the bobbin could be improved and that the bobbin could, in certain circumstances, be partially or totally extracted from the tooth.

[0006] During motor manufacturing, this requires taking special precautions when handling the core. Later, during operation, this can be detrimental to the reliability of the winding.

[0007] Therefore, there is a real need for a technical solution that allows the coil to be firmly immobilized on the tooth that carries it.

[0008] The invention satisfies this need by proposing a core comprising means for immobilizing the coils.

[0009] To this end, the invention proposes a sheet metal core for a rotor or stator of an electrical machine, said core being made up of a spiral winding, turn after turn, of a sheet metal strip around an axis X comprising an alternation of tabs and slots, in particular of increasing widths as said winding is carried out, a superposition of said tabs and said slots delimiting respectively in said core teeth and gaps,

[0010] in which at least one projection extends from at least one edge of at least one of said teeth.

[0011] The presence of the projections allows cooperation with a coil, in particular to scratch the inside of a coil inserted on the tooth after its manufacture, to prevent its spontaneous extraction.

[0012] According to various additional features of the invention, which may be taken together or separately and which constitute so many embodiments of the invention:

[0013] - at least one projection is in continuity of material with said tooth,

[0014] - at least one protrusion is elastically deformable,

[0015] - at least one projection is a first projection that originates from at least one edge of one of the ridges of the tooth,

[0016] - said edge is a lateral edge forming part of a lateral edge of at least one of said teeth,

[0017] - the tooth has at least two initial projections that are opposed transversely with respect to the X-axis,

[0018] - the first two opposing projections, transversely relative to the X-axis, originate from the same tongue,

[0019] - the tooth has at least two initial projections aligned parallel to the X axis along the lateral edge of one of the ridges of said tooth,

[0020] - the tooth has at least two radially aligned initial projections, originating from tongues associated with different spiral turns of said tooth,

[0021] - the first two radially aligned projections are superimposed and originate from superimposed tongues of said tooth resulting from at least two consecutive spiral turns to form groups of first radially aligned projections,

[0022] - the first projections or groups of first projections aligned radially are derived from tabs arranged between one in five and one in twenty turns of the spiral,

[0023] - the tooth has at least one second projection which extends substantially radially from a free face of a tongue of a first or last turn of the spiral.

[0024] The invention also relates to a winding armature for a rotor or stator of an electric machine, comprising a sheet metal core of the type described above, and coils received on the teeth of said core, each coil being immobilized on the tooth associated by said at least one projection.

[0025] According to other characteristics of the frame:

[0026] - each coil has a through-hole with a profile substantially complementary to a tooth,

[0027] - each spool is made of a plastic material, specifically a material susceptible to creep,

[0028] - each protrusion is elastically deformed in the associated coil in a direction opposite to the direction of introduction of said tooth into the coil, to prohibit subsequent dismantling of the tooth.

[0029] The invention finally relates to a rotor or stator of an electrical machine comprising a winding armature of the type described above, and a winding made on its coils.

[0030] The invention also relates to a method for manufacturing a sheet metal core of the type described above, comprising the steps of:

[0031] i) unwinding a raw sheet metal strip from a sheet metal coil to a winding unit with an X-axis, the sheet metal coil having its axis parallel to the X-axis,

[0032] (ii) use a punching unit to punch said sheet metal strip blank between the sheet metal coil and the winding unit so as to form in said blank a sheet metal strip having tabs and slots, in particular of increasing widths as said winding is carried out in the winding unit,

[0033] in which during step ii) straight-edged tabs and tabs having said at least one projection, or at least a thickness of said at least one projection, are selectively formed.

[0034] . Brief description of the figures

[0035] The invention will be better understood, and other objects, details, features and advantages thereof will become more apparent from the following detailed explanatory description of at least one embodiment of the invention, given by way of purely illustrative and non-limiting example, with reference to the accompanying schematic drawings, among which:

[0036] Laest is a perspective view, in exploded view mode, of a stator and a coil of an electrical machine according to a first embodiment of the invention;

[0037] Laest is a perspective view, in exploded view mode, of a stator and a coil of an electrical machine according to a second embodiment of the invention;

[0038] Laest is a half-view in phantom perspective of a part of an electrical machine according to the invention;

[0039] This is a perspective view of a winding and punching unit for manufacturing the first embodiment of the stator of the;

[0040] Laest is a cross-sectional view by plane 5-5 of the beginning of the introduction of a coil onto a tooth of the stator of the, said tooth being made according to a first embodiment of the invention;

[0041] This is a cross-sectional view by plane 5-5 of the end of the introduction of the bobbin onto the tooth of the;

[0042] This is a cross-sectional view by plane 7-7 of a second embodiment of a stator tooth;

[0043] This is a cross-sectional view by plane 5-5 of a third embodiment of a stator tooth of the;

[0044] This is a perspective view of a winding and punching unit for the manufacture of a second embodiment of the stator of the;

[0045] This is a view along the Y-axis of the strip for the manufacture of the second embodiment of the stator of the;

[0046] This is a view along the X-axis of the strip for the manufacture of the second embodiment of the stator of the;

[0047] This is a block diagram illustrating the steps of a process for manufacturing the sheet metal core according to the invention. Detailed description of the invention

[0048] In the description that follows, identical reference numbers denote identical parts or parts with similar functions.

[0049] Figures 1 and 2 show a core 10 of a stator of an axial flux electric machine 11 made according to the invention, and a coil 12 intended to cooperate with this core 10. The core 10 and the coil 12 are intended to be used in an electric machine 11 which has been shown in Figure 1. The electric machine 11 and its components will be described with reference to the directions of the trihedral axis "X, Y, Z" where "X" designates an axial direction coinciding with an axis of rotation of the electric machine 11, "Y" designates a first radial direction substantially perpendicular to the axial direction "X", and "Z" designates a second radial direction perpendicular to the axial direction "X" and to the first radial direction "Y".

[0050] The sheet metal core 10 is substantially annular and essentially consists of a flat ring 16 with axis X extending from a face 16, from which a plurality of teeth 20 are regularly spaced angularly around axis X. The teeth 20 are separated by gaps 22. Each tooth 20 has a substantially angular sector shape. Figures 1 and 2 show eighteen teeth 20 and eighteen gaps 22, although this configuration is not limiting to the invention.

[0051] The core 10 is designed to receive windings 12, preferably on all its teeth 20. Each winding 12 comprises a body 24 with a through recess 26 having a profile substantially complementary, or even homothetic, to a tooth 20. The body 24 is adapted to be received on one of the teeth 20 penetrating its recess 26 in a direction parallel to the X-axis. One periphery of the body 24 has a peripheral groove 28 on which, as illustrated in the figure, a winding wire 30 can be wound in successive turns. The entire core 10 and the winding(s) 12 form a winding armature 13 as shown in the figure.

[0052] As illustrated, the electric machine 11 mainly comprises a casing 32 with a housing 34 receiving a stator 36, consisting of the core 10, the coils 12, and the winding wire 30. The stator 36 is here centered on the axis X, which is also the axis of rotation of a rotor (not shown) by means of a fixed hub 40 which is attached to the casing and which is intended to be traversed by the rotor shaft.

[0053] As schematically illustrated in Figure 1, the core 10 is obtained by means of a process consisting of winding a sheet metal strip 44 spirally around an axis X, in the direction of the arrow in Figure 1. The strip 44 has alternating tabs 46 and slots 48, preferably of increasing widths, as the winding 42 is performed.

[0054] The slots 48 and the tabs 46 are obtained here by cutting a blank of sheet metal 52 with a first punch 50, which passes in front of said first punch 50 as it is wound. With each turn of the winding 42, the tabs 46 of that turn overlap the tabs of the previous turn, and finally, an overlap of said tabs 46 and said slots 48 delimits, respectively, the teeth 16 and the gaps 18 in the core 10. Once the appropriate number of turns has been obtained, the finished winding 42 forms the core 10.

[0055] According to the invention, as illustrated in Figures 1, 2, and 5 to 8, at least one projection 54, 56 extends from at least one edge 58, 60, 62 of at least one of the teeth 20.

[0056] As can be seen in particular in Figures 1 and 2, each tooth 20 has two lateral edges 58 extending radially between an inner transverse edge 60 and an outer transverse edge 62 of the tooth 20. Each lateral edge 58 lies in a radial plane passing through the X-axis. At least one projection 54 extends from a lateral edge 58 of a tooth 20, as shown in Figure 1. Alternatively, or in combination, at least one projection 56 extends from a transverse edge of the tooth 20, namely the inner transverse edge 60 and / or the outer transverse edge 62.

[0057] This at least one projection 54, 56 allows, when inserting the coil 12 onto the associated tooth 20, to scratch the inside of the through recess 26 of the coil 12 by locally penetrating the material of the coil 12 and to immobilize it in order to prevent its extraction and / or its spontaneous movement along the direction X, in particular under the effect of vibrations of the motor.

[0058] Advantageously, each projection 54, 56 is preferably elastically deformable. In this way, when the tooth 20 is inserted into the through recess 26 of the coil 12, each projection 56, 56 deforms elastically in the associated coil 12 in a direction opposite to the direction of insertion of said tooth 20 into the coil 12, to prevent subsequent disassembly of the tooth 20. We will now describe the different configurations of projections 54, 56 with reference to the different embodiments of the invention which are shown in the figures.

[0059] According to the invention, regardless of the embodiment of the invention chosen, at least one projection 54, 56 is in continuity of material with the tooth 20.

[0060] The invention takes advantage of the manufacturing process of the core 10 to produce this projection 54, 56 in continuity of material with the tooth 20.

[0061] As illustrated in Figures 4, 9 and 12, a manufacturing process for core 10 comprises the following steps:

[0062] i) unwinding a raw sheet metal strip 52 from a sheet metal coil (not shown) to a winding unit 64 with axis X where the winding 42 is carried out, the sheet metal coil having an axis parallel to the X axis,

[0063] ii) use a punching unit 66 to punch said blank 52 of sheet metal strip between the sheet metal coil and the winding unit 64 so as to form in said blank 52 the sheet metal strip 44 having slots 48 and tabs 46, of slots and widths increasing as the winding 42 is carried out in the winding unit 64.

[0064] According to the invention, in step ii) the punching unit 66 is advantageously used to produce, for example with the first punch 50, straight-edged tabs 46 and, for example with an additional punch 68, 70, tabs 46 capable of having said at least one projection 54, 56. Once superimposed in the winding 42, the tabs 46 having the projection(s) 54, 56 are integrated into the tooth 20 which, as a result, has said at least one projection 54, 56.

[0065] Said at least one projection 54, 56 allows the spool 12 to be immobilized on the tooth 20 by penetrating the recess 26 of the spool 12. Preferably, each spool 12 is made of a plastic material, in particular a material capable of creep to facilitate anchoring of the projection(s) 54, 56 in the material of the spool. As a result of this creep, said spool advantageously has a ridge cooperating with said projection(s) 54, 56.

[0066] The invention proposes several types of embodiment of the projection 54, 56.

[0067] According to a first embodiment of the invention associated with the method shown in Figure 1, at least one projection is a first projection 54 which originates from at least one edge 72 of one of the tabs 46 of the tooth. Here, the edge 72 forms part of one of the lateral edges 58 of the tooth 20. In the configuration shown here, this edge 72 is parallel to the X-axis and, like the lateral edge 58 of the tooth 20, lies in a radial plane passing through the X-axis.

[0068] In this case, during step ii) the additional punch is a special second punch 68 which is suitable for cutting tabs 46 whose edge 72 directly has said at least a first projection 54, as shown in the.

[0069] As can be seen in Figure 1, which shows in section one of the teeth 20 formed as a stack of tabs 46, one of the tabs 46, namely the illustrated tab 46, has at least one first projection 54 extending transversely with respect to the axial direction X. In this figure, the tab 46 is shown flat before winding. The first projections are thus shown in the plane of the tab 46, moreover before insertion of the bobbin 12. In the specific case shown in Figures 5 and 6, and without limiting the invention, the tooth 20 has two first projections 54 that are transversely opposed.

[0070] Furthermore, the first two projections 54 opposite transversely 54 with respect to the X axis originate from the same tongue 46.

[0071] As we have seen, each first projection 54 is intended, as illustrated by the laa, to deform elastically by entering the recess 26 of the bobbin 12.

[0072] This allows each first projection 54 to penetrate a corresponding wall 74 of the recess 26.

[0073] Furthermore, the elastic deformation of the first projection 56 in a direction opposite to the direction of introduction of said tooth 20 into the coil 12, makes it possible to prohibit the subsequent dismantling of the tooth 20, the tooth 20 and its first projections 54 then presenting a harpoon configuration in the recess 26 of the coil 12.

[0074] To achieve this result, with regard to the functional clearances between the tooth 20 equipped with at least one projection 54 and the bobbin 12, the bobbin 12 and the tooth 20 are configured so that, as illustrated in Figure 1, a sum of the clearances J1 and J2 of two opposing walls 74 of said recess 26 with the tooth 20 is less than a sum of the dimensions E1, E2 of at least one first projection 54 cooperating with a corresponding wall of the recess 26. As can be seen in Figure 1, this configuration necessarily causes the elastic deformation of the first projections 54 by making them flex when the tooth is introduced into the recess 26.

[0075] In general, without limiting the invention, it is desirable that the tongue 46 have at least two first projections 54 opposed transversely with respect to the X axis. This configuration makes it possible to center the coil 12 on the tooth 20 by distributing the clearances J1 and J2 on either side of the tooth 20. The coil 12 is then gripped on either side of the tooth 20 by the two first opposing projections 54.

[0076] Several configurations of first projections 54 carried by a lateral edge 58 of the tooth 20 are then conceivable.

[0077] As schematically illustrated, which represents a tooth 20 made up of a stack of tongues 46, the tooth 20 can have at least two first radially aligned projections 54, originating from tongues 46 associated with different turns of the spiral of the tooth 20.

[0078] On the, tooth 20 has three pairs of opposing tongues 54 originating from three tongues 46.

[0079] The first radially aligned 54 projections are for example spaced and originate from tongues 46 arranged between one in five and one in twenty turns of spiral, i.e. between a tongue 46 of the stack 42 in five and a tongue 46 of the stack 42 in twenty.

[0080] Alternatively (not shown), either or cumulatively, the first two radially aligned projections 54 may be superimposed, in which case they originate from superimposed tabs 56 of said tooth 20 resulting from at least two consecutive spiral turns. Superimposing the projections 54 allows for a more robust and rigid grouping of projections 54.

[0081] As an alternative or in combination of either of the two previous configurations, as schematically illustrated by the diagram which represents a tooth 20 in the plane of a tongue 46, the tooth 20 may have at least two first projections 54 aligned parallel to the X axis along the lateral edge 72 of one of the tongues 56 of said tooth 20.

[0082] According to a second embodiment of the invention associated with the process which has been represented in the figure, the tooth 20 has at least a second projection 56 which is substantially radially offset from a free face 76, 78 respective of a tongue 46 of a first and / or last turn of spiral.

[0083] This configuration allows us to propose at least one projection 56 extending along a direction substantially tangential to the radial direction Z.

[0084] There are several ways to perform this second protrusion 56.

[0085] Preferably, as illustrated in the figure, said at least one second projection 56 consists of a tab 55 cut out of the tongue 46 of the first and / or last turn of the spiral, and folded back with respect to said free face 76 or 78. This cutout 55 has been shown in the band 44 in the figure.

[0086] In this case, according to the process described above, during step ii) the additional punch is a third punch 70 suitable for cutting the leg 55 in at least some of the tabs 46 of the first and / or last spiral turn.

[0087] A straightening unit 80, arranged between the punching unit 66 and the winding unit 64, is schematically represented on the diagram. This unit allows the tabs 55 under the strip 44 to be bent substantially perpendicular to the free faces 49 of the tabs, in the direction of the arrow. This straightening unit 80 allows the tabs 55 to be bent prior to the winding of the strip 44.

[0088] In this case, the process described above includes a step iii) subsequent to step ii) in which the straightening unit 80, arranged between the punching unit 66 and the winding unit 64, bends said tabs 54 substantially perpendicular to the free faces of the tongues 46. Step iii) has been represented by dashed lines on the.

[0089] Of course, it will be understood that the legs 55 can also be folded manually once the winding 42 has been carried out to reach the core 10.

[0090] Alternatively (not shown), at least a second projection 56 could be obtained without cutting. For example, the second projection 56 could consist of a stamping of the free face 49 of the strip 44 intended to form the free face 76, 78 of the finger 20, said stamping extending opposite said free face 76, 78.

[0091] In this case, the process includes a step iv) subsequent to step ii) in which a stamping unit (not shown), arranged between the punching unit 66 and the winding unit 64, stamps the tabs 46 of the first and / or last spiral turns opposite their free faces 76, 78 after step ii). Step iv) has been shown in dashed lines on the.

[0092] Step iv) can also be prior to step ii). In this case the stamping unit (not shown) is arranged between the sheet coil and the punching unit 66 and stamps the future location of the tabs 46 of the first and / or last spiral turns opposite their free faces 76, 78 before step ii).

[0093] As a further variant of the invention, the second projection 56 could be made by adding material (for example by brazing) directly onto the free faces 76, 78.

[0094] Similarly to the case of the at least one first projection, the sum of the clearances of two other opposite walls of the recess 26 with the tooth 20 is less than the sum of the dimensions of the at least one second projection 56 cooperating with said walls of the recess. This configuration is analogous to the configuration previously described with reference to the at least one first projection, but considered in the radial direction Z.

[0095] In the preferred embodiment of the invention, in order to ensure optimal fixing of all the coils 12, each tooth 20 has said at least one first or second projection 54, 56. In addition, optimal centering of the coils 12 on the teeth 20 is obtained when each tooth 20 has both first projections 54 and second projections 56.

[0096] The invention makes it possible to propose a rotor or stator of an electrical machine comprising a reliable winding armature 13 capable of guaranteeing the stability of a winding 30 made on its coils 12.

Claims

Sheet metal core (10) for a rotor or stator (36) of an electric machine, said core (10) being made of a spiral winding (42) of a strip (44) of sheet metal around an axis X comprising an alternation of tabs (46) and slots (48), in particular of increasing widths as said winding (42) is made, a superposition of said tabs (46) and said slots (48) delimiting respectively in said core teeth (20) and gaps (22), in which at least one projection (54, 56) extends from at least one edge (58, 60, 62) of at least one of said teeth (20). Core (10) made of sheet metal according to any one of the preceding claims, wherein at least one projection (54, 56) is in continuity of material with said tooth (20). Core (10) made of sheet metal according to any one of the preceding claims, wherein at least one projection is a first projection (54) which is issued from at least one edge (72) of one of the tabs (46) of the tooth (20). Core (10) made of sheet metal according to the preceding claim, in which said edge (72) is a lateral edge forming part of a lateral edge (58) of at least one of said teeth (20). Core (10) made of sheet metal according to the preceding claim, in which the tooth (20) has at least two first projections (54) opposed transversely with respect to the X axis. Core (10) made of sheet metal according to any one of claims 3 to 5, in which the tooth (20) has at least two first projections (54) aligned parallel to the X axis along the lateral edge (72) of one of the tabs (46) of said tooth. Core (10) made of sheet metal according to any one of claims 3 to 6, in which the tooth (20) has at least two first radially aligned projections 54, originating from tabs (46) associated with different turns of the spiral of said tooth (20). Core (10) made of sheet metal according to any one of the preceding claims, in which the tooth (20) has at least a second projection (56) which is substantially radially offset from a free face (60, 62) of a tongue (46) of a first or last turn of spiral. Armature (13) for winding a rotor or stator of an electric machine, comprising a sheet metal core (10) according to any one of the preceding claims, and coils (12) received on the teeth (20) of said core (10), each coil (12) being immobilized on the tooth (20) associated by said at least one projection (54, 56). Winding armature (13) according to the preceding claim, wherein each coil (12) is made of a plastic material, in particular a material capable of creeping. Rotor or stator (36) of an electrical machine comprising a winding armature (13) according to one of claims 9 or 10, and a winding (30) made on its windings (12). A method for manufacturing a sheet metal core (10) according to any one of claims 1 to 8, comprising the steps of: i) unwinding a blank (52) of sheet metal strip from a sheet metal coil to a winding unit (64) with axis X, the sheet metal coil having an axis parallel to the X axis; ii) using a punching unit (66) to punch said blank of sheet metal strip (52) between the sheet metal coil and the winding unit (64) so ​​as to form in said blank (52) the sheet metal strip (44) having tabs (46) and notches, in particular of increasing widths (48) as said winding (42) is carried out in the winding unit (64), wherein in step ii) tabs (46) with straight edges and tabs adapted to include said at least one projection (54, 56), or at least one thickness of said at least one projection (54, 56).

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