ROTATING ELECTRICAL MACHINE

Abstract

A rotating electrical machine including a stator and a rotor having a rotor mass and permanent magnets, which are arranged on the surface of the rotor mass. The permanent magnets include a face which is directed towards the stator and is of a generally concave form. The permanent magnets of the rotor form poles of the rotor, in which the permanent magnet(s) of a same pole have an angular offset (a) between two longitudinal ends of the machine.

Claims

1. A rotating electrical machine comprising: a stator and a rotor comprising a rotor mass and permanent magnets which are arranged on the surface of the rotor mass, the permanent magnets comprising a face which is directed towards the stator and which is of generally concave form, the permanent magnets of the rotor forming poles of the rotor, the permanent magnet(s) of a same pole having an angular offset (a) between two longitudinal ends of the machine.

2. The rotating electrical machine according to claim 1, wherein the rotor mass comprises a socket to which the permanent magnets are fixed.

3. The rotating electrical machine according to claim 1, wherein each pole comprises at least one twisted permanent magnet.

4. The rotating electrical machine according to claim 3, wherein the angular offset (α) between each of the two longitudinal ends of the permanent magnet being between 1° and 5°.

5. The rotating electrical machine according to claim 1, wherein each pole comprising a plurality of permanent magnets which are angularly offset relative to each other.

6. The rotating electrical machine according to claim 5, wherein the rotor comprising at least two assemblies composed of a socket and permanent magnets which are fixed to the socket and which are arranged in a circumferential row, the two assemblies being arranged symmetrically with respect to each other relative to a transverse plane of the machine.

7. The rotating electrical machine according to claim 5, wherein the angular offset (α) between two consecutive permanent magnets of the same pole being between 0.8° and 2.5°.

8. The rotating electrical machine according to claim 1, wherein the rotor comprising 16 poles.

9. The rotating electrical machine according to claim 1, wherein the rotor is internal.

10. The rotating electrical machine according to claim 1, wherein a concave face of a permanent magnet of the rotor comprises a concave portion, having a width which is measured perpendicularly relative to a radius of the rotor between 2 and 56 mm.

11. The rotating electrical machine according to claim 10, wherein the greatest depth (p) of the concavity of the concave portion, measured along a radius of the rotor, is between 0.05 and 3 mm.

12. The rotating electrical machine according to claim 10, wherein the concave portion is a circle portion or an ellipse portion in cross section.

13. The rotating electrical machine according to claim 1, wherein the concave portion of a concave face is arranged between two planar lateral portions.

14. The rotating electrical machine according to claim 1, wherein the permanent magnets of the rotor having a thickness (h), measured along a radius of the rotor, between 1.5 and 10 mm.

15. The rotating electrical machine according to claim 1, wherein a ratio (p/h) between the greatest depth of the concavity of the concave portion, measured along a radius of the rotor, and the thickness of a permanent magnet being between 0.01 and 0.9.

16. The rotating electrical machine according to claim 1, wherein the permanent magnets are fixed to the rotor mass of the rotor by means of adhesive bonding.

17. The rotating electrical machine according to claim 1, wherein the permanent magnets comprise a fixing face which is opposite the concave face, directed towards the stator and planar.

18. The rotating electrical machine according to claim 1, the stator having concentrated winding comprising teeth and coils that are arranged on the teeth.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0100] The invention may be better understood from a reading of the following detailed description of non-limiting embodiments thereof and an examination of the appended drawings, in which:

[0101] FIG. 1 is a schematic, partial view of a rotating electrical machine according to the invention.

[0102] FIG. 1a is a perspective, schematic partial view of the rotor of FIG. 1.

[0103] FIG. 2a is a cross section of a permanent magnet of the machine of FIG. 1.

[0104] FIG. 2b is a longitudinal section of a permanent magnet of the machine of FIG. 1.

[0105] FIG. 3 is a view similar to FIG. 1 of a variant.

[0106] FIG. 4 is a schematic, partial view of a variant.

DETAILED DESCRIPTION

[0107] FIGS. 1 and 1a illustrate a rotating electrical machine 1 according to the invention, comprising an external stator 10 and an internal rotor 20 which comprises a rotor mass 25 comprising a shaft 21 and permanent magnets 22 which are arranged on the surface of the rotor mass 25

[0108] The stator 10 has in the example described a concentrated winding. The stator 10 comprises teeth 11 which each carry an individual coil 12 which is arranged on the corresponding tooth. The coils 12 are electrically connected to each other so as to be supplied by a three-phase current.

[0109] The teeth of the stator comprise pole shoes 13. The opening o of the notches of the stator, measured circumferentially, between the pole shoes 13 is, for example, in the order of 1.5 mm.

[0110] The bore of the stator, which corresponds to the internal diameter of the stator, is in the order of 90 mm.

[0111] The stator further comprises an external frame which surrounds the cylinder head and which is not illustrated.

[0112] On the rotor, the shaft 21 is massive, being hollow at the centre thereof and providing a space 27.

[0113] In accordance with the invention and as illustrated in detail in FIGS. 2a and 2b, the permanent magnets 22 of the rotor comprise a face 23 which is directed towards the stator, which is generally of concave form. The face 23 of the magnets directed towards the stator corresponds to the face of the magnets opposite the rotation axis X of the machine.

[0114] The concave face 23 of a permanent magnet 22 of the rotor comprises a concave portion 24.

[0115] The width l of the concave portion 24, measured perpendicularly to a radius of the rotor, in cross section, is in the order of 9 mm in the example described.

[0116] The width L of a permanent magnet 22 of the rotor measured perpendicularly to the rotation axis, in cross section, is in the order of 19 mm.

[0117] The greatest width p of the concavity of the concave portion, measured along a radius of the rotor, in cross section is in the order of 0.5 mm.

[0118] The greatest depth of the concavity of the concave portion, measured along a radius of the rotor, is in the example described located at the centre of the concave face of the corresponding permanent magnet. The permanent magnet is symmetrical relative to a plane P which intersects it at the centre thereof, this plane passing through the rotation axis of the machine and a radius of the rotor.

[0119] The concave portion 24 is in the example described in cross section a circle portion, having a radius R in the order of 20 mm.

[0120] The concave portion 24 of the concave face 23 is arranged between two planar lateral portions 26.

[0121] The width e of a planar lateral portion measured perpendicularly to a radius of the rotor, in cross section, is in the order of 2 mm.

[0122] The concave portion constitutes in the example described approximately 75% of the total width of the corresponding magnet.

[0123] The permanent magnets of the rotor have, when the machine is viewed along the rotation axis, a cross section which is generally rectangular with a long side which is orientated perpendicularly to a radius of the machine.

[0124] The permanent magnets 22 of the rotor have a thickness h, measured along a radius of the rotor, in cross section, in the order of 3 mm.

[0125] A ratio p/h between the greatest depth p of the concavity of the concave portion, measured along a radius of the rotor, and the thickness h of the permanent magnet 22 is in the order of 0.2.

[0126] The rotor and the stator provide between them an air gap 30. The air gap has a width, measured along a radius of the machine, in cross section, in the order of 0.9 mm. The width d.sub.0 of the air gap, measured along a radius which extends through the centre of a magnet 22, in cross section, is in the order of 1.5 mm.

[0127] The bore of the rotor, which corresponds to the external diameter of the rotor, is in the order of 50 mm.

[0128] The permanent magnets 22 of the rotor comprise a fixing face 28 which is opposite the concave face 23, directed towards the stator and, in the example described, of planar form. The planar face is orientated perpendicularly to the radius which extends through the rotation axis and which intersects the corresponding magnet at mid-length.

[0129] The permanent magnets 22 are fixed to the rotor mass 25 by means of adhesive bonding in a housing 29 which is provided to this end on the surface thereof. The housing 29 has a planar surface which corresponds to the shape of the fixing face of the magnets.

[0130] The concave face 23 may comprise one or more concave portions 24 and one or more planar portions 26, as illustrated above, or be completely concave, as illustrated by way of example in FIG. 3.

[0131] In this example, in the absence of a planar lateral portion, the concave portion 24 constitutes 100% of the total width of the corresponding magnet.

[0132] In accordance with the invention, and as can be seen in FIG. 1a, the permanent magnets 22 of the rotor 20 form poles of the rotor. The permanent magnets of the same pole have an angular offset α between two longitudinal ends of the machine, as illustrated in FIG. 1a.

[0133] In the example described, the rotor mass comprises a socket 35 to which the permanent magnets are fixed, for example, by means of adhesive bonding. The socket(s) may be fixed, for example, by means of adhesive bonding, to the shaft 21 of the machine which may be smooth.

[0134] The socket 35 may be formed by a stack of metal sheets. The socket 35 may be single, carrying all the permanent magnets of the rotor. In a variant, the rotor mass may comprise a plurality of sockets.

[0135] Furthermore, each pole of the rotor comprises two permanent magnets 22 which are offset angularly relative to each other by a specific angle. The permanent magnets are straight, that is to say, not twisted.

[0136] The angular offset α between two consecutive magnets of the same pole is in the example described 1.25°. Furthermore, an angular offset between the first magnet and the last magnet of the same pole is in this example 1.25°.

[0137] In this manner, the rotor comprises a plurality of circumferential rows of permanent magnets 22, that is to say, two in this example. All the permanent magnets 22 of the same circumferential row are fixed to the same socket 35 mentioned above.

[0138] The rotor therefore comprises two assemblies which are each composed of a socket 35 and permanent magnets 22 which are arranged in a circumferential row. The two assemblies may be identical.

[0139] In the example described, they are both arranged symmetrically with respect to each other relative to a transverse plane of the machine. Such a configuration enables the angular offset to be produced as a result of the overturning of one assembly relative to the other.

[0140] To this end, the socket 35 comprises two through-holes 36 for rods in order to enable the socket(s) 35 to be clamped around the shaft 21 of the machine. The holes 36 are positioned in such a manner that, when a socket 35 is placed symmetrically relative to another socket 35, an angular offset is obtained between the permanent magnets which they carry.

[0141] The holes 36 are positioned below and at the centre of the magnet. They are offset relative to each other by substantially 180°. These two holes 36 are not precisely in the axis of the centre of the magnet, but instead offset by an angle equal to half of the angular offset, that is, for example, 0.625°. Each socket being identical, by overturning one of the two sockets by 180° about the axis X, the angular offset is generated between the sockets.

[0142] In a variant, it is also possible to fret the sockets without adhesive bonding. The fretting involves heating a socket with a very tight internal diameter in order to expand it and to fit it to the shaft. Another possibility is to machine the housings of the magnets directly onto the shaft.

[0143] In a variant which is illustrated in FIG. 4, each pole may comprise a twisted permanent magnet 22 which extends along a longitudinal axis Y which is inclined through an angle α relative to the axis X of the machine. In this example, each pole comprises a single twisted magnet, but, in a variant, it may comprise a plurality of them.

[0144] In this manner, there is an angular offset a between each of the two longitudinal ends of the permanent magnet 22. The angular offset α between each of the two longitudinal ends of each permanent magnet 22 is, for example, 2.5°.

[0145] In the examples considered, the rotor comprises 16 poles and the stator 18 comprises teeth. The scope of the present invention is not exceeded if the number thereof is different.

[0146] The invention is not limited to the embodiments which have been described above and the rotor may, for example, comprise a different number of poles and the same applies to the teeth of the stator.

[0147] Furthermore, in the example described, the rotor is internal, but it remains within the scope of the present invention if the rotor is external, or if the machine comprises both an internal rotor and an external rotor which are each arranged radially at one side and the other of the stator and which are coupled in terms of rotation.

[0148] The machine may be used not only as a motor but also as a generator in order to carry out energy recovery, for example.

[0149] The machine according to the invention may have applications other than the motorisation of robots.