Shim for holding a winding of a rotor, wound rotor and electric motor comprising such a shim

Abstract

The invention relates to a shim (20) for holding at least one winding of a rotor provided with wound teeth, which comprises a one-piece polyhedral body (34) extending predominantly along a longitudinal axis (L2), the body (34) being intended to be inserted between two circumferentially consecutive teeth of the rotor and to bear against at least one winding of one of the two consecutive teeth, a frustoconical hole (22) being formed through the body (34) of the shim (20), a straight generatrix (36) of the frustoconical hole (22) being parallel to the longitudinal axis (L2) of the body (34) of the shim (20).

Description

Description Title of the invention: Wedge for holding a rotor winding, wound rotor and electric motor comprising such a wedge. Technical field

[0001] The technical field of the present invention is wound rotor electric motors.

[0002] In particular, the present invention relates to a wedge for holding at least one winding of a rotor provided with wound teeth, a wound rotor and an electric motor comprising such a holding wedge. Previous techniques

[0003] A rotor of electrical machines generally comprises a disc rotating about a longitudinal axis and teeth extending radially from the disc.

[0004] Each tooth of the rotor has a winding wound around the tooth.

[0005] The rotor includes shims to hold the windings while the disc rotates.

[0006] Each shim is inserted circumferentially between two successive teeth of the rotor and is in contact with the windings of the two successive teeth.

[0007] The wedge is, for example, in the shape of a triangular prism. The wedge includes a hole extending longitudinally through the wedge.

[0008] The rotor comprises two crowns arranged longitudinally on either side of the disc, as well as tie rods, each tie rod being inserted into the hole of a shim and being fixed to the two crowns.

[0009] In particular, a clearance remains around each tie rod inserted into the hole of a wedge, the clearance extending longitudinally over at least part of the longitudinal dimension of the hole.

[0010] The tie rods are subjected to centrifugal force during the rotation of the disc, causing the tie rods to bend or even rupture due to fatigue. Statement of the invention

[0011] The present invention therefore aims to overcome all or part of the aforementioned drawbacks and to provide a wedge for a wound rotor reducing the risk of breakage of a tie rod passing through the wedge.

[0012] The present invention relates to a wedge for holding at least one winding of a rotor provided with wound teeth, the wedge comprising a polyhedral body obtained in a single piece and extending mainly along a longitudinal axis, the body being intended to be inserted between two circumferentially successive teeth of the rotor and to come to bear against at least one winding of one of said two successive teeth, a frustoconical hole being formed through the body of the wedge, a generating line of the frustoconical hole being parallel to the longitudinal axis of the body of the wedge.

[0013] Preferably, the body of the wedge is obtained in a single piece by molding, the frustoconical hole resulting in particular from the use of an inclined rod arranged in the body of the wedge during molding, the rod being inclined at a clearance angle facilitating its removal during demolding of the body of the wedge, the shape of the frustoconical hole then resulting from the clearance angle.

[0014] Advantageously, the frustoconical hole extends between a first plane defining a first circular end of the frustoconical hole and a second plane parallel to the first plane and defining a second circular end of the frustoconical hole, said generatrix being orthogonal to the first plane and to the second plane.

[0015] The shim may comprise a composite material and / or a thermoplastic material including in particular a polysulfone.

[0016] Advantageously, the body of the wedge is substantially in the shape of a prism.

[0017] Advantageously, a transverse section of the body of the wedge is substantially in the shape of a triangle.

[0018] Optionally, at least one wall of the body of the wedge extending at least partly longitudinally has a longitudinal convergence angle.

[0019] Optionally, the wedge comprises at least one head extending longitudinally from the body of the wedge, the dimensions of the cross-section of the head reducing as it moves longitudinally away from the body of the wedge.

[0020] Preferably, the shim is obtained in one piece by molding.

[0021] The present invention also relates to a wound rotor comprising a rotating disc, a plurality of teeth extending radially from the disc, a plurality of windings each surrounding a tooth of the rotor, at least one shim as defined above, the body of the shim being inserted between two circumferentially successive teeth so that said generating line of the frustoconical hole is parallel to the axis of rotation of the disc, the body of the shim bearing against at least one winding of one of said two successive teeth, the rotor comprising two fixing rings arranged longitudinally on either side of the disc, and at least one tie rod inserted into the frustoconical hole of the shim and fixed to the rings.

[0022] The truncated hole makes it possible to radially hold the tie rod inserted in the truncated hole, in particular a tie rod in the shape of a right circular cylinder, the tie rod then being able to undergo thermal expansion within the truncated hole.

[0023] The tie rod, extending longitudinally between the two crowns, rests against the said generating line of the truncated cone hole parallel to the axis of rotation of the disc without deforming.

[0024] Preferably, said generating line is the generating line of the truncated hole. the furthest radially from the center of the rotating disk, the tie rod then resting on said generating line without deforming during the rotation of the rotating disk.

[0025] The present invention also relates to an electric motor comprising a stator and a wound rotor as defined above. Brief description of the drawings

[0026] Other aims, characteristics and advantages of the invention will appear on reading the following description, given solely by way of non-limiting example and made with reference to the appended drawings in which:

[0027] [Fig.l] schematically illustrates an electric motor according to the invention;

[0028] [Fig.2] schematically illustrates a transverse section of a rotor according to the invention;

[0029] [Fig.3] schematically illustrates a longitudinal section of the rotor of [Fig.2];

[0030] [Fig.4] schematically illustrates a wedge according to a first exemplary embodiment of the invention;

[0031] [Fig.5] schematically illustrates a truncated cone-shaped hole in the wedge of [Fig.4];

[0032] [Fig.6] schematically illustrates a wedge according to a second exemplary embodiment of the invention; and

[0033] [Fig.7] schematically illustrates a wedge according to a third exemplary embodiment of the invention. Detailed description

[0034] [Fig.l] schematically represents an electric motor 2, for example an electric motor of a motor vehicle.

[0035] The electric motor 2 comprises a stator 4 and a rotor 6 in particular provided with a central opening to accommodate and drive a transmission shaft 8, the rotor 6 being intended to be rotated around a longitudinal axis L1.

[0036] [Fig. 2] schematically represents a cross-section of a central part of the rotor 6. The rotor 6 comprises a rotating disc 10 and a plurality of teeth 12 radially extending the disc 10, the teeth 12 here being regularly spaced along the circumference of the disc 10.

[0037] Each tooth 12 comprises a radial portion 14 extending, for example, purely radially. Each tooth 12 also comprises a head 16, radially extending the radial portion 14, in particular by forming an ortho-radial projection relative to the radial portion 14.

[0038] The rotor 6 comprises a plurality of windings 18, each winding 18 being wound around a radial portion 14 of a tooth 12.

[0039] The rotor 6 comprises a plurality of holding wedges 20, each holding wedge 20 being inserted between two successive teeth 12 in the circumferential direction of the disc 10 so that each wedge 20 bears against the winding 18 of the two circumferentially successive teeth 12, in particular in order to prevent the winding 18 from extending ortho-radially beyond the heads 16 of the two circumferentially successive teeth 12.

[0040] Each wedge 20 includes a truncated hole 22.

[0041] Advantageously, the shim 20 is retained radially by the two circumferentially successive teeth 12. For example, the shim 20 bears radially against the head 16 of each of the two circumferentially successive teeth 12.

[0042] [Fig.3] schematically represents a longitudinal section of the rotor 6 of [Fig.2].

[0043] The rotor 6 comprises two fixing rings 24 arranged longitudinally on either side of the disc 10 as well as a plurality of tie rods 26.

[0044] Each tie rod 26 is fixed at a first end to one of the two crowns 24, and at the other end to the other crown 24, each tie rod 26 thus being inserted into the frustoconical hole 22 of a wedge 20. For example, each tie rod 26 is threaded and fixed to the crowns 24 by means of a nut 28 or a tapping made in a crown 24.

[0045] [Fig.4] schematically represents a front view of a holding wedge 20 representing the front face 30 of the wedge 20, the wedge 20 comprising a rear face 32 similar to the front face 30 at the opposite longitudinal end of the wedge 20.

[0046] The wedge 20 comprises a polyhedral body 34 obtained in a single piece, in particular by molding.

[0047] The polyhedral body 34 of the wedge 20 extends mainly along a longitudinal axis L2, the polyhedral body 34 being intended to be inserted between two circumferentially successive teeth 12 of the rotor 6 and to come to bear against the windings 18 of the two successive teeth 12 so that the longitudinal axis L2 of the polyhedral body 34 of the wedge 20 is parallel to the longitudinal axis of rotation L1 of the disc 10 of the rotor 6.

[0048] The frustoconical hole 22 of the wedge 20 is formed through the polyhedral body 34 of the wedge 20, between the front face 30 and the rear face 32 of the wedge 20, so that a generating line 36 of the frustoconical hole 22 is parallel to the longitudinal axis L2 of the polyhedral body 34 of the wedge 20.

[0049] Thus, said generating line 36 of the truncated hole 22 is parallel to the longitudinal axis of rotation L1 of the disc 10 of the rotor 6 when the shim 20 is inserted between the two circumferentially successive teeth 12.

[0050] The transverse section of the polyhedral body 34 of the wedge 20 is substantially in the shape of a triangle, the side of smaller dimension 38 of which is intended to be arranged radially on the outside when the wedge 20 is inserted between the two circumferentially successive teeth 12.

[0051] Preferably, said generating line 36 is the generating line of the truncated hole 22 closest to the side of smaller dimension 38 of the triangle of the substantially triangular shape of the polyhedral body 34 of the wedge 20.

[0052] Said generating line 36 is intended to be the generating line of the frustoconical hole 22 furthest radially from the center of the rotating disc 10. Thus, the tie rod 26 passing through the frustoconical hole 22 bears on said generating line 36 without deforming during the rotation of the rotating disc 10.

[0053] In the example shown, the angles of the polyhedral body 34 of the wedge 20 are truncated.

[0054] Preferably, the shim 20 comprises an electrically insulating material. For example, a composite material and / or a thermoplastic material and / or a polysulfone.

[0055] Advantageously, the shim 20 comprises a radial extension 40 extending the side of smaller dimension 38 of the triangular shape of the polyhedral body 34 of substantially triangular section of the shim 20, the radial extension 40 being intended to come into ortho-radial support against the teeth 12 of the rotor 6, in particular against the heads 16 of the teeth 12 of the rotor 6.

[0056] The truncated hole 22 of the wedge 20 is illustrated in more detail in [Fig.5],

[0057] The frustoconical hole 22 is a portion of a cone taken between a first plane defining a first circular end 42 of the frustoconical hole 22 and a second plane parallel to the first plane and defining a second circular end 44 of the frustoconical hole 22.

[0058] The truncated hole 22 is formed of an infinity of generating lines. The first circular end 42 and the second circular end 44 are defined as being the intersections of the generating lines of the cone with the first plane and with the second plane.

[0059] The longitudinal direction L2 along which the polyhedral body 34 of the wedge 20 mainly extends is orthogonal to said parallel planes.

[0060] Said generating line 36 parallel to the longitudinal axis L2 along which the polyhedral body 34 of the wedge 20 mainly extends is therefore orthogonal to the foreground and to the second plane.

[0061] The longitudinal direction L2 of the polyhedral body 34 of the wedge 20 forms a non-zero angle α with the straight line passing through the center of the circle of the first circular end 42 of the frustoconical hole 22 and through the center of the circle of the second circular end 44 of the frustoconical hole 22, this angle α corresponding in particular to a correction of a clearance angle generated by the molding of the polyhedral body 34 of the wedge 20.

[0062] [Fig.6] schematically represents a second example of the embodiment of the retaining wedge 20.

[0063] The cross-section of the polyhedral body 34 of the wedge 20 is substantially of the shape of a triangle whose angles extending the side of smaller dimension 38 have been truncated, in particular so as to form bearing surfaces intended to come into radial support against the heads 16 of the two circumferentially successive teeth 12.

[0064] The polyhedral body 34 of the wedge 20 is substantially in the shape of a triangular prism, the shape of the cross sections of the polyhedral body 34 of the wedge 20 being identical between the front face 30 and the rear face 32 of the wedge 20.

[0065] The surface area of ​​the front face 30 of the wedge 20 is greater than the surface area of ​​the rear face 32 of the wedge 20, the walls of the wedge 20 extending substantially longitudinally and having a longitudinal convergence angle, the surface area of ​​the cross-sections of the wedge 20 decreasing linearly between the front face 30 of the wedge 20 and the rear face 32 of the wedge 20. The convergence angle promotes, for example, the demolding of the wedge 20.

[0066] The wedge 20 comprises a second body 46 substantially in the shape of a triangular prism, having the same convergence angle as the polyhedral body 34 of the wedge 20, and radially extending the apex of the substantially triangular shape of the polyhedral body 34 opposite the smaller dimension side 38 of the triangle of the substantially triangular shape of the polyhedral body 34 of the wedge 20. The second body 46 notably allows simplified insertion of the wedge 20 between the two circumferentially successive teeth 12, the thickness of the windings 18 being generally smaller in the vicinity of the longitudinal axis of rotation L1 of the disc 10.

[0067] Alternatively, the polyhedral body 34 and / or the second body 46 are prism-shaped and do not have the convergence angle.

[0068] [Fig.7] schematically represents a third example of the embodiment of the retaining wedge 20.

[0069] The polyhedral body 34 of the wedge 20 is substantially in the shape of a triangular prism.

[0070] The wedge 20 comprises two heads 48 each longitudinally extending the polyhedral body 34 of the wedge 20.

[0071] The dimensions of the cross-sections of each head 48 of the wedge 20 are reduced as they move away longitudinally from the polyhedral body 34 of the wedge 20. The heads 48 of the wedge 20 facilitate in particular the insertion of the wedge 20 between the two circumferentially successive teeth 12.

[0072] Optionally, several holding wedges 20 are inserted longitudinally between the two circumferentially successive teeth 12, said wedges 20 following one another longitudinally.

Claims

Claims

1. Wedge (20) for holding at least one winding (18) of a rotor (6) provided with wound teeth (12), the wedge (20) comprising a polyhedral body (34) obtained in one piece and extending mainly along a longitudinal axis (L2), the body (34) being intended to be inserted between two circumferentially successive teeth (12) of the rotor (6) and to come to bear against at least one winding (18) of one of said two successive teeth (12), a frustoconical hole (22) being formed through the body (34) of the wedge (20), characterized in that a generating line (36) of the frustoconical hole (22) is parallel to the longitudinal axis (L2) of the body (34) of the wedge (20).

2. A wedge (20) according to claim 1, wherein the frustoconical hole (22) extends between a first plane defining a first circular end (42) of the frustoconical hole (22) and a second plane parallel to the first plane and defining a second circular end (44) of the frustoconical hole (22), said generatrix being orthogonal to the first plane and to the second plane.

3. Wedge (20) according to one of claims 1 and 2, obtained in a single piece by molding.

4. Wedge (20) according to any one of claims 1 to 3, comprising a composite material and / or a thermoplastic material comprising in particular a polysulfone.

5. A wedge (20) according to any one of claims 1 to 4, wherein the body (34) of the wedge (20) is substantially prismatic in shape.

6. A wedge (20) according to any one of claims 1 to 5, wherein a cross-section of the body (34) of the wedge (20) is substantially in the shape of a triangle.

7. A wedge (20) according to any one of claims 1 to 6, wherein at least one wall of the body (34) of the wedge (20) extending at least partly longitudinally has a longitudinal convergence angle.

8. A wedge (20) according to any one of claims 1 to 7, comprising at least one head (48) extending longitudinally the body (34) of the wedge (20), the dimensions of the cross-section of the head (48) reducing as it moves longitudinally away from the body (34) of the wedge (20).

9. A wound rotor (6) comprising a rotatable disc (10), a plurality of teeth (12) extending radially from the disc (10), a plurality of windings (18) each surrounding a tooth (12) of the rotor (6), characterized in that it comprises at least one shim (20) according to any one of claims 1 to 8, the body (34) of the shim (20) being inserted between two circumferentially successive teeth (12) so that said generating line (36) of the frustoconical hole (22) is parallel to the axis of rotation (L1) of the disc (10), the body (34) of the shim (20) bearing against at least one winding (18) of one of said two successive teeth (12), the rotor (6) comprising two fixing rings (24) arranged longitudinally on either side of the disc (10), and at least one tie rod (26) inserted into the frustoconical hole (22) of the shim (20) and fixed to the rings (24).

10. Electric motor (2) comprising a stator (4) and a rotor (6) wound according to claim 9.

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