Rotor for electric machine

Abstract

The invention relates to a rotor (10) of an electric machine, rotating about an axis of rotation X, the rotor comprising: - a rotor body (12) comprising a succession of salient poles (14) forming notches (16) therebetween; - a plurality of coils (20), each coil (20) being arranged around the corresponding salient pole (14) in the notches (16) adjacent to this salient pole (14); - coil-holding wedges (30), each wedge (30) being arranged in a notch (16) so as to come into contact with the coil (20) of a first salient pole (14) and with the coil (20) of a second salient pole consecutive to the first, the rotor (10) being characterised in that each of the holding wedges (30) comprises a wedge head (32) extended by a wedge foot (34), the free end of the foot (37) being oriented towards the bottom of the notch, the foot (34) at least partially coming into contact with the coils (20) of the first and second salient poles.

Description

Description Title of the invention: rotor for an electric machine Technical field

[0001] The present invention relates to a rotor for an electrical machine, in particular a wound rotor, in particular an ortho-cyclic wound rotor with a number of poles greater than 4.

[0002] The invention also relates to an electric machine comprising such a rotor. Technological background

[0003] Wound rotors typically have coils wound around salient poles. These coils are designed to carry a direct current of varying intensity. Given the nature of the coil wire materials and the rotor's rotational speed, it is essential to securely hold these coils to the corresponding rotor poles.

[0004] In fact, the coils are subjected to centrifugal forces during the rotation of the rotor, these forces are all the more important as the diameter of the rotor and its rotation speed are high.

[0005] To improve the holding of the coils, holding wedges, also called "rotor wedges", are provided for this purpose. These are inserted into the notches between the salient poles and exert a thrust on the coils so as to hold them against the pole bodies.

[0006] These wedges generally have a roughly V-shaped cross-section.

[0007] This type of shim is not entirely satisfactory. In fact, it does not provide optimal support for the coils. There is therefore a risk of fatigue failure of the coil wires due to bending under heavy loads.

[0008] The function of holding the coils on the pole body is important to prevent them from spinning out, as mentioned above

[0009] It would therefore be desirable to secure the coils even more effectively from centrifugation occurring during rotor operation. Summary of the invention

[0010] The invention aims to meet this objective and achieves it by means of an electric machine rotor, rotating around an axis of rotation X, the rotor comprising: - a rotor body comprising a succession of salient poles forming notches between them, - a plurality of coils, each coil being arranged around the corresponding salient pole in the notches adjacent to this salient pole, - coil holding wedges, each wedge being arranged in a notch so as to come into contact with the coil of a first salient pole and the coil of a second salient pole consecutive to the first, said rotor being characterized in that each of the holding wedges comprises a wedge head extended by a wedge foot, the free end of the foot being oriented towards the bottom of the notch, said foot coming at least partially into contact with the coils of the first and second salient poles.

[0011] The wedges according to the invention ensure, thanks to their shape, that the entire height of the wound poles is maintained. This results in better resistance of the coil wires to centrifugation. This makes it possible to increase the maximum permissible rotational speed of the rotor accordingly.

[0012] Preferably, the wedge foot has a polygonal cross-section, such as square, rectangular or triangular.

[0013] By "cross section" is meant any section made in a plane orthogonal to an axis of elongation of the retaining wedge.

[0014] Preferably, the wedge foot has a constant cross-section from its free end to its junction with the wedge head.

[0015] Alternatively, the wedge foot has a cross-section of variable shape and / or dimension along the axis of elongation of the retaining wedge. For example, the foot may have a section widening towards the free end of the foot.

[0016] Preferably, the wedge foot extends over a length measured along the axis of elongation of the holding wedge, adapting to the shape of the winding.

[0017] The wedge foot may have a smooth external surface.

[0018] Alternatively, the retaining wedge comprises one or more reliefs extending laterally from the wedge base.

[0019] The presence of reliefs on the external surface of the wedge foot allows for even better retention of the coils on the rotor poles.

[0020] The relief(s) may be projecting reliefs. Preferably, the relief(s) extend in the direction of the coils, the reliefs preferably extending perpendicular to the axis of elongation of the retaining wedge.

[0021] The relief(s) may extend along extension axes forming the same angle with the elongation axis of the support wedge.

[0022] The relief(s) may extend along extension axes forming different angles with the elongation axis of the support wedge.

[0023] The surface relief(s) may be outwardly convex in shape. The outwardly convex surface relief(s) may be boss-shaped.

[0024] The boss-shaped relief(s) may have a surface in the shape of a spherical cap or a quadric of revolution, in particular an ellipsoid.

[0025] Preferably, the relief(s) extend along extension axes extending from the same longitudinal plane of the foot.

[0026] At least two reliefs may extend from opposite faces of the wedge foot.

[0027] At least two reliefs can extend from the same face of the wedge foot.

[0028] At least two reliefs may extend over the wedge foot at the same height relative to the base of the foot.

[0029] At least two reliefs may extend at different heights of the foot relative to the base of the foot.

[0030] The wedge head may have a polygonal cross-section. Preferably, the wedge head has a cross-section that decreases as it approaches the junction with the foot.

[0031] The wedge head can be viewed from the front in the shape of a trapezoid, rectangle or triangle.

[0032] By "front view" we mean a view along an axis perpendicular to the plane of elongation of the support wedge.

[0033] The retaining wedge can be in the shape of a “Y” or a “T” from the front.

[0034] The retaining wedge is preferably made of plastic.

[0035] Preferably, the retaining wedge is monolithic.

[0036] By "monolithic" we mean that the retaining wedge is in the form of a single block.

[0037] Preferably, the holding wedges are arranged in the corresponding notches so that the axis of elongation of the holding wedge is oriented radially, i.e. following a radial axis of the rotor.

[0038] Alternatively, the elongation axis is inclined relative to a radial axis of the rotor by an angle adapting to the number of poles.

[0039] Each pole may comprise a radially extending pole body on which the corresponding coil is surrounded. The pole also comprises a pole head extending in an ortho-radial direction.

[0040] Advantageously, the wedge head has two shoulders, each of which bears against the pole heads of the first and second poles respectively.

[0041] The retaining wedge may be full.

[0042] The rotor body has one or more magnetic laminations.

[0043] The rotor has a number of poles greater than 4.

[0044] The invention also relates to an electric machine comprising a rotor as described above.

[0045] The invention also relates to a vehicle, in particular a motor vehicle, comprising a rotor according to the invention and / or an electric machine according to the invention. Brief description of the figures

[0046] The invention may be better understood by reading the detailed description which follows, by examining the non-limiting example of its implementation, and by examining the attached drawing in which:

[0047] [Fig.l] [Fig.1] is a schematic and partial section of a rotor according to the invention;

[0048] [Fig.2] [Fig.2] is a detail of [Fig.l], and

[0049] [Fig.3] [Fig.3] illustrates another example of a holding wedge according to the invention. Description of embodiment(s)

[0050] [Fig.l] shows a rotor 10 of an electric machine according to the invention rotating around an axis X.

[0051] As illustrated, the rotor 10 comprises a rotor body 12 consisting of a plurality of magnetic laminations 13. The rotor body 12 comprises a succession of salient poles 14 forming notches 16 between them.

[0052] Each salient pole 14 comprises a radially extending pole body 15 and an enlarged pole head 17 extending in an ortho-radial direction.

[0053] Each pole body 15 is surrounded by a coil 20. This coil 20 is received in the notches 16 adjacent to this salient pole 14.

[0054] The rotor further comprises shims 30 which are arranged in the notches 16 and which are intended to hold the coils against the poles 15.

[0055] As can be seen in the figures, each wedge 30 comes into contact with the coil 20 of a first salient pole 14 and the coil 20 of a second salient pole following the first. By its position and shape, the wedge exerts a thrust on the coils so as to hold them against the pole bodies of the first and second salient poles.

[0056] The retaining wedges 30 each have an elongation axis Y which is oriented radially, that is to say following a radial axis of the rotor.

[0057] As illustrated, the holding wedges 30 each comprise a wedge head 32 extended by a foot 34.

[0058] The wedge head 32 has a polygonal cross-section in the example shown. The wedge head 32 is in the form of a trapezoid in front view, the wedge head having a cross-section that decreases as it approaches the junction with the foot.

[0059] The wedge head 32 has two shoulders 33 which bear against the internal faces of the pole heads 32.

[0060] The wedge foot 34 has a rectangular cross-section. In the example illustrated, the wedge foot 34 has a constant cross-section from its free end 37 to its junction 39 with the wedge head 32. It thus has, with a view to face a general rectangular shape.

[0061] The wedge foot 34 extends over a length l measured along the elongation axis Y of the holding wedge 30, adapting to the shape of the winding.

[0062] This length l represents approximately 25% of the total length L of the retaining wedge 30 in the example illustrated.

[0063] In the example illustrated in particular in [Fig.2], the retaining wedge comprises several reliefs 35, here two in number, extending laterally from the wedge base 34.

[0064] In the example illustrated, the relief(s) 35 are projecting reliefs and extend towards the coils 20. The latter are of identical shape and are in the form of a convex boss towards the outside. The reliefs 35 have a rounded shape.

[0065] The two reliefs 35 extend from opposite faces of the wedge foot 34, along an extension axis P perpendicular to the elongation axis Y. As can be seen in the figures, these reliefs extend at the same height h relative to the base of the foot 37.

[0066] Alternatively, the wedge feet may have a smooth external surface, i.e. without reliefs, as illustrated in [Fig.3].

[0067] The invention is not limited to the examples which have just been described.

[0068] The wedge foot can have a different shape.

[0069] The number of reliefs can be other than two. The reliefs can be wavy in shape.

Claims

Claims

1. Rotor (10) of an electric machine, rotating around an axis of rotation X, the rotor comprising: - a rotor body (12) comprising a succession of salient poles (14) forming notches (16) between them, - a plurality of coils (20), each coil (20) being arranged around the corresponding salient pole (14) in the notches (16) adjacent to this salient pole (14), - coil holding wedges (30), each wedge (30) being arranged in a notch (16) so as to come into contact with the coil (20) of a first salient pole (14) and the coil (20) of a second salient pole consecutive to the first, said rotor (10) being characterized in that each of the holding wedges (30) comprises a wedge head (32) extended by a wedge foot (34), the free end of the foot (37) being oriented towards the bottom of the notch, said foot (34) coming at least partially into contact with the coils (20) of the first and second salient poles.

2. Rotor according to claim 1, the wedge foot (34) having a polygonal cross-section, preferably the wedge foot having a constant cross-section from its free end to its junction with the wedge head.

3. Rotor according to one of claims 1 and 2, the wedge foot extending over a length measured along the axis of elongation of the retaining wedge, representing between 5% and 60% of the total length of the retaining wedge.

4. Rotor according to one of the preceding claims, the holding wedge (30) comprises one or more reliefs (35) extending laterally from the wedge base (34).

5. Rotor according to claim 4, the relief(s) (35) being projecting reliefs, preferably extending in the direction of the coils (20), the surface relief(s) preferably being convex outwards, in particular in the form of a boss.

6. Rotor according to claim 4 or 5, the relief(s) (35) extending along extension axes (P) forming the same angle with the elongation axis (Y) of the retaining wedge, in particular a right angle with the elongation axis of the retaining wedge.

7. Rotor according to one of claims 4 to 6, at least two reliefs (35) extending from opposite faces of the wedge foot, preferably at the same height (h) relative to the base of the foot (34).

8. Rotor according to any one of the preceding claims, the retaining wedge (30) being solid.

9. Rotor according to any one of the preceding claims, the wedge head (32) having a polygonal cross-section, in particular decreasing as it approaches the junction with the foot.

10. Rotor according to any one of the preceding claims, the wedge head (32) having two shoulders (33) each coming into contact with the internal faces of the heads (17) of the first and second poles (14) respectively.

11. An electrical machine comprising a rotor (10) according to any one of the preceding claims.

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