ROTOR FOR A ROTATING ELECTRICAL MACHINE

Abstract

A rotor for an electrical machine, rotating about an axis of rotation, the rotor including: salient poles forming slots between them, the salient poles each being of an overall shape that is asymmetrical with respect to a radial midplane containing the axis of rotation of the machine, coils, each coil being placed on a corresponding salient pole, in the slots adjacent to this salient pole.

Claims

1. An electrical machine comprising a rotor, rotating about an axis of rotation, the rotor comprising: salient poles forming slots between them, the salient poles each being of an overall shape that is asymmetrical with respect to a radial midplane containing the axis of rotation of the machine, coils, each coil being placed on a corresponding salient pole, in the slots adjacent to this salient pole, and a stator comprising teeth defining slots between them.

2. The electrical machine as claimed in claim 1, wherein each salient pole comprises a lateral pole shoe, notably on a first lateral face of the salient pole, when the rotor is observed along the axis of rotation.

3. The electrical machine as claimed in claim 2, the salient pole comprising a second lateral face on the opposite side to the first lateral face, which is devoid of a pole shoe.

4. The electrical machine as claimed in claim 3, the second lateral face extending in a radial plane or making an angle with a radial plane passing through its base.

5. The electrical machine as claimed in claim 3, the second lateral face forming a non-zero angle with the first lateral face.

6. The electrical machine as claimed in claim 1, the coils having been inserted on the corresponding salient poles after they have been wound.

7. The electrical machine as claimed in claim 1, wherein a coil comprises first and second portions housed in two adjacent slots, the first and second portions being situated respectively at distances from the axis of rotation, the distances being equal or different.

8. The electrical machine as claimed in claim 1, wherein a coil is held on the corresponding salient pole by an adjacent coil and/or by a pole shoe.

9. A rotor of an electrical machine, the rotor comprising: salient poles forming slots between them, the salient poles each being of an overall shape that is asymmetrical with respect to a radial plane containing an axis of rotation of the machine, coils, each coil being placed on a corresponding salient pole, in the slots adjacent to the salient pole, in which rotor at least one coil comprises first and second portions housed in two adjacent slots, the first and second portions being situated respectively at distances from the axis of rotation, the distances being different.

10. A rotor of an electrical machine, rotating about an axis of rotation, the rotor comprising: salient poles forming slots between them, the salient poles each being of an overall shape that is asymmetrical with respect to a radial midplane containing the axis of rotation of the machine, each salient pole comprising a lateral pole shoe, when the rotor is observed along the axis of rotation, the salient pole comprising a second lateral face on the opposite side to the first lateral face, which is devoid of a pole shoe, coils, each coil being placed on a corresponding salient pole, in the slots adjacent to the salient pole.

11. A rotating electrical machine comprising a rotor as claimed in claim 9 and a stator.

12. The electrical machine as claimed in claim 1, the stator comprising a toothed ring comprising teeth defining between them slots open radially toward the outside, and a yoke attached to the toothed ring.

13. The machine as claimed in claim 12, the stator comprising windings placed in a distributed fashion in the slots, notably having electrical conductors arranged in the slots.

14. A method for manufacturing a rotor of an electrical machine as claimed in claim 2, or a rotor comprising: salient poles forming slots between them, the salient poles each being of an overall shape that is asymmetrical with respect to a radial midplane containing the axis of rotation of the machine, each salient pole comprising a lateral pole shoe, when the rotor is observed along the axis of rotation, the salient pole comprising a second lateral face on the opposite side to the first lateral face, which is devoid of a pole shoe, coils, each coil being placed on a corresponding salient pole, in the slots adjacent to the salient pole, the method comprising the following steps: a) preparing a coil on a core, the coil comprising first and second portions which are intended to be housed in slots of the rotor, b) inserting a first portion of the coil in a first slot adjacent to the first lateral face of a salient pole, the first lateral face comprising a lateral pole shoe, c) inserting a second portion of the coil in a second slot adjacent to the second lateral face of the salient pole.

15. The method as claimed in claim 14, wherein the first portion of the coil is held under the pole shoe of the corresponding salient pole bearing the coil or under a second coil inserted subsequently.

16. The method as claimed in claim 14, wherein the second portion of the coil is held under the pole shoe of a salient pole adjacent to the salient pole bearing the coil or under a second coil inserted subsequently.

17. The method as claimed in claim 14, wherein the coil is deformed at the time of its insertion.

18. The method as claimed in claim 14, wherein the coil is offset at the time of its insertion, notably circumferentially, so as to hold it under a pole shoe.

19. The method as claimed in claim 14, comprising the following steps: i) the first portions of all the coils are inserted all at once into the corresponding slots, then ii) the second portions of all the coils are inserted all at once into the corresponding slots, the coils are offset circumferentially, notably so as to hold a coil on the corresponding salient pole by means of an adjacent coil and/or by means of a pole shoe.

Description

DETAILED DESCRIPTION

[0123] The invention may be better understood from reading the following detailed description of nonlimiting exemplary embodiments thereof, and from studying the attached drawing in which:

[0124] FIG. 1 is a schematic and partial view, in transverse section, of a rotating electrical machine according to the invention,

[0125] FIGS. 2a and 2b are views in transverse section of the machine of FIG. 1, respectively showing the induction and the flux lines in the machine,

[0126] FIGS. 3a to 3c are views similar to FIG. 1 of variant positionings of the coils on the salient poles,

[0127] FIG. 4 is a view similar to FIG. 1 of a variant embodiment of a stator,

[0128] FIG. 5 is a schematic and partial perspective view of a variant machine, and

[0129] FIG. 6 is a view similar to FIG. 1 of an embodiment variant.

[0130] FIG. 1 illustrates a rotating electrical machine 10 comprising an internal rotor 1 and an external stator 2. The stator makes it possible to generate a rotary magnetic field driving the rotation of the rotor 1, in the context of a synchronous motor, and, in the case of an alternator, the rotation of the rotor induces an electromotive force in the stator windings.

[0131] The stator 2 comprises windings 22, as illustrated, which are placed in slots 21 formed between teeth 23 of a toothed ring 25. Furthermore, the stator comprises a yoke 29 attached to the toothed ring 25. The stator further comprises an external frame, not depicted, surrounding the yoke.

[0132] The windings 22 are placed in a distributed manner in the slots 21 and have electrical conductors arranged in the slots 21.

[0133] The slots 21 in the example described have mutually parallel radial edges and in transverse section are rectangular in overall shape.

[0134] The slots 21 are closed toward the airgap by tangential bridges 27 joining together two consecutive teeth of the toothed ring 25. The tangential bridges 27 are of a width which is non-constant, decreasing and then increasing.

[0135] The toothed ring 25 is produced by winding into a helix a strip of teeth which are connected by tangential bridges 27. The teeth 23 of the strip create between them the slots 21 which have convergent edges, the edges of the slots being mutually parallel when the strip is wound on itself to form the toothed ring.

[0136] Each slot 21 comprises two stacked windings, and therefore two winding stages.

[0137] The thickness e of the yoke may be relatively great, in comparison with known machines. The same is true of the width l of the teeth. In this way it is possible to obtain a significant reduction in the consumption of electrical field (or ampere-turns) at the stator, or else a significant increase in the flux passing through the stator.

[0138] The rotor 1 depicted in FIG. 1 comprises a magnetic rotor mass 3 extending axially along the axis of rotation X of the rotor, this rotor mass being for example formed by a pack of magnetic laminations stacked along the axis X, the laminations being, for example, identical and exactly superposed. They may be held together by clipping, by rivets, by tie rods, by welding or by any other technique. The magnetic laminations are preferably made of magnetic steel. All grades of magnetic steel can be used.

[0139] The rotor mass 3 comprises a central opening for mounting on a shaft 5. The shaft may, in the example considered, be made of a nonmagnetic material, for example of nonmagnetic stainless steel or of aluminum, or on the other hand may be magnetic.

[0140] According to the invention, the rotor 1 comprises salient poles 13 creating between them slots 11. The rotor 1 further comprises coils 12, each coil being placed on a corresponding salient pole 13, in the slots 11 adjacent to said salient pole.

[0141] The salient poles 13 have an overall shape that is asymmetrical with respect to a radial midplane containing the axis of rotation X of the machine. The salient poles 13 each comprise a lateral pole shoe 14, situated on a first lateral face 14a of the salient pole, when the rotor is observed along the axis of rotation X, toward the free end of the salient pole. In the example described, the lateral pole shoe is situated on the rear lateral face of the salient pole. The salient poles comprise a second lateral face 14b on the opposite side to the first lateral face 14a, which is devoid of pole shoe and may at its end have a chamfer 14c facilitating the insertion of the coils.

[0142] The circulation of the flux in this example is offset toward the front in the direction of rotation of the rotor, as illustrated in FIGS. 2a and 2b. Saturation in the salient pole is reached less rapidly.

[0143] The second lateral face 14b extends in a plane that makes an γ with a radial plane Z.

[0144] The second lateral face 14b makes an angle β with the first lateral face 14a. This angle β is non-zero. The first and second lateral faces are not parallel to one another.

[0145] The positioning of the coils in the slots 11 will now be described with reference to FIGS. 3a to 3c.

[0146] Each coil 12 comprises first 12a and second 12b portions housed respectively in two adjacent slots 11.

[0147] These first and second portions 12a and 12b may be situated respectively at distances d1 and d2 from the axis of rotation X which are different, as illustrated in FIGS. 3a and 3b. When the distances d1 and d2 are different, the coil is deformed, its first and second portions being connected by a curved coil portion. In the example of FIG. 3a, the coil is held on the corresponding salient pole on one side by an adjacent coil and, on the other, by a pole shoe 14 of the adjacent salient pole. In the example of FIG. 3b, the coil is held on the corresponding salient pole on one side by an adjacent coil and, on the other, by a pole shoe 14 of the corresponding salient pole.

[0148] In a variant, the coil comprises first and second portions housed in two adjacent slots, said first and second portions being situated at the same distance d1 from the axis of rotation X. This coil is held on the corresponding salient pole by the two adjacent coils.

[0149] Another coil comprises first and second portions housed in two adjacent slots, said first and second portions being situated at the same distance d2 from the axis of rotation X. This coil is held on the corresponding salient pole by two pole shoes of the two adjacent salient poles.

[0150] Thus, the rotor comprises an alternation of coils of which the first and second portions are situated at the same distance d1 from the axis of rotation X, and of coils of which the first and second portions are situated at the same distance d2 from the axis of rotation X.

[0151] In this way, all the coils are held on the corresponding salient pole by an adjacent coil and/or by a pole shoe.

[0152] In the embodiment variant illustrated in FIG. 4, the stator differs from that of FIG. 1 in terms of the shape of the slots 21 formed between the teeth 23 of the stator. These slots are hexagonal in overall shape, shaped like the point of a diamond. The electrical conductors in these slots are in transverse section circular in shape. The arrangement thereof is a hexagonal arrangement. Furthermore, in this example, the yoke 29 is equipped with semicircular longitudinal ribs 31 intended to house ducts 30 for the circulation of a cooling liquid.

[0153] The rotor coils may comprise a plurality of turns. The turns of one coil may be offset, as illustrated in FIG. 5, something which may make it possible to encourage their cooling. Cooling may also be encouraged via the space left in the coils and between the coils, in the slots.

[0154] Furthermore, the machine may comprise a fan 40 placed on the shaft at the level of the tips of the coils, in order to encourage their cooling even more.

[0155] In the example of FIG. 1, the number of rotor poles is 8. It would not constitute a departure from the scope of the present invention if this number were different. The machine may, for example, comprise 6 salient poles at the rotor, as illustrated in FIG. 6.

[0156] The rotor is obtained by means of the method of manufacture which will now be described in detail.

[0157] In a preparatory step, the coils are prepared on cores. Each coil comprises first and second portions which are intended to be housed in rotor slots.

[0158] The first portion of the coil is then inserted in a first slot adjacent to the first lateral face of a salient pole, this first lateral face comprising the lateral pole shoe.

[0159] Finally, the second portion of the coil is inserted in a second slot adjacent to the second lateral face of the salient pole.

[0160] In particular, the first portions of all the coils are inserted all at once in the corresponding slots, then the second portions of all the coils are inserted all at once into the corresponding slots.

[0161] Finally, the coils are offset circumferentially, notably so as to hold a coil on the corresponding salient pole by means of an adjacent coil and/or by means of a pole shoe.

[0162] The assembly obtained can be impregnated before being inserted into the stator prepared elsewhere.

[0163] Of course, the invention is not restricted to the exemplary embodiments which have just been described.

[0164] The expression “comprising a” is to be understood as being synonymous with “comprising at least a”.