WO2019207240A1

WO2019207240A1 - Stator for a rotary electric machine comprising a magnet with optimized volume

Info

Publication number: WO2019207240A1
Application number: PCT/FR2019/050943
Authority: WO
Inventors: Nicolas Labbe; Gautier TREMOUILLE
Original assignee: Valeo Equipements Electriques Moteur
Priority date: 2018-04-25
Filing date: 2019-04-19
Publication date: 2019-10-31

Abstract

The invention relates to a stator comprising a longitudinal axis O, a neodymium-, iron- and boron-based magnet with a support face in contact with an internal surface of a yoke (10 of a stator (1) for a rotary electric machine, the magnet comprising a radial thickness (E) of the magnet (4) which varies angularly along the profile of the magnet (4) and in which a reduced portion (42, 48) of the magnet comprises an offset surface (402) on its support face, closer than a support surface (402) of a thick portion (43, 46) of the longitudinal axis O.

Description

STATOR OF A ROTATING ELECTRIC MACHINE COMPRISING A VOLUME MAGNET

OPTIMIZE

The field of the present invention is that of rotating electrical machines. The invention relates more specifically to starters for a motor vehicle equipped with such a rotating electrical machine.

Motor vehicle starters with machines are known

rotating electric. Such a rotating electrical machine is provided with a stator, also called inductor, and a rotor, also called armature, the rotor and the stator being separated by a gap.

The stator of such a machine is constituted by a cylindrical cylinder head and a magnetized structure formed by permanent magnets generally made of ferrite. The magnetized structure is then formed of permanent magnets disposed in pairs symmetrically opposite one another, each permanent magnet forming a magnetic pole.

The rotor comprises notches in which conductors forming the winding of such a rotating electrical machine are arranged. These conductors are intended to be supplied with direct current by a battery of a vehicle via a contactor of the starter. The conductors of the rotor are successively fed by grouping the same sign of current under each polarity of the inductor. The direct current supply of the conductors of the armature, said armature current, makes it possible to establish, via the armature, a magnetomotive force in the air gap of the rotating electrical machine. This magnetomotive force is translated by a magnetic field of armature, called armature reaction, compared to a magnetic induction established by the poles

Magnetic inductor. The interaction of the armature magnetic field and the magnetic induction finally produces a motor torque rotating the rotor of the rotating electrical machine.

Traditional magnets traditionally used are in the form of compact blocks and are generally fixed by gluing or stapling inside the stator yoke of the rotating electrical machine. These compact blocks have a constant radial thickness resulting mainly from convenience in their implementation but impose a high material cost. Indeed, this radial thickness is determined to be sufficiently high in view, firstly, to allow the establishment in the gap of a vacuum magnetic induction in the absence of armature current and other on the other hand, to avoid irreversible demagnetization of the magnets in the presence of the armature magnetic field produced in the opposite direction of the magnet on an angular side of the magnet. Such demagnetization of a permanent magnet results in a point of operation of the armature magnetic field in the direction opposite or near a coercive field of the magnet representing its ability to resist irreversible demagnetization.

The magnetic induction established by the inductor is quasi-constant, whereas the magnetic field of armature is asymmetrical. Thus, for each of the poles of a pair of magnetic poles of the inductor, a first part of the magnet of the magnetic pole is subjected to a magnetic field of armature of the same sign as this first part of the magnet and a second part of the magnet of the same magnetic pole is subjected to an armature magnetic field of opposite sign to that of this second part of the magnet. The magnetic armature field then tends to demagnetize the magnet by this second part. Such a phenomenon is therefore taken into account in the design and manufacture of permanent magnets by increasing the radial thickness of the magnet relative to the need of the machine to resist this demagnetization of the magnet.

The present invention thus aims to remedy at least one of these disadvantages, by proposing a stator of a rotating electrical machine comprising magnets having a reduced material cost without impairing the performance of the engine torque of the rotating electrical machine. .

For this purpose, the subject of the invention is a stator intended to equip a rotating electrical machine, the stator comprising:

A cylindrical cylinder head along a longitudinal axis of the stator comprising an internal surface, and

At least one magnet based on neodymium, iron, boron magnetized regularly radially with respect to an axis towards the longitudinal axis O or parallel to a plane comprising the axis and passing through the magnet the longitudinal axis, mounted against the breech, the magnet comprising:

an air gap face facing the axis O having a radius of curvature and

a support face opposite to the air gap face, the support face being in contact with the internal surface of the yoke and comprising:

i a contact surface of a thick portion of the magnet and

ii an offset surface of a reduced portion of the magnet, and in that the contact surface is further away from the O axis than the offset surface.

In the prior art, the support surface of the magnet is angularly regular with respect to the axis O and comprises a cylindrical support contact surface in contact with the internal surface of the cylinder head. In the invention, the support surface of the Neodymium, Iron, Boron magnet comprises a support contact surface and an offset surface closer to the X axis than the support contact surface. This implies that the magnet comprises a thick portion comprising the support contact surface having a radial thickness of the magnet measured in a radius of the longitudinal axis greater than the radial thickness in a reduced portion of the magnet having the surface offset from the support face. Thus this difference in radial thickness of the magnet involves a radially measured thickness of magnet which varies along a curved profile of the magnet.

By radial thickness of the magnet is therefore meant a thickness of the magnet measured along a radius of the axis O of the yoke.

In other words, the radial thickness of the magnet varies by having an irregularly angular support surface with respect to the axis O.

As a result, there is a reduction in the volume of the magnet and therefore in the cost of the material.

With this magnet whose thickness varies along the curved profile of the magnet, it is possible to significantly reduce the material cost of the magnets used without affecting the performance of the engine torque of the rotating electrical machine. Indeed, in a rotating electrical machine comprising this stator and a rotor, when these magnets are mounted on the stator yoke to form pair pairs of magnetic poles, for each magnetic pole, a thick portion of the magnetic pole magnet is subjected to a rotor armature magnetic field of sign opposite to the sign of the magnet without however demagnetizing the magnet by this thick portion, and a reduced portion of the magnet of the same magnetic pole is subjected to a magnetic field of induces the rotor of the same sign of the magnet while producing a sufficiently high torque. Thus, only the portion undergoing the reverse magnetic field comprises a thick portion to avoid demagnetization.

Thus, the reduced portion of the magnet is arranged to be opposite the magnetic field in the same direction as the magnet and comprising the offset support surface and therefore has a smaller radial thickness than the same part of a magnet. of the prior art. This reduced portion therefore has a thickness measured radially lower than that of the thick portion whose magnetic field of armature is of opposite sign relative to the magnet. Thus we add the material of the magnet to avoid demagnetization only where it undergoes a magnetic field opposite to that of the magnet. The sizing of the magnets is then optimized so that it is possible to reduce the volume of the magnet and therefore its cost while allowing the formation of sufficient motor torque.

It will be noted that the stator comprising the irregular magnet operates for an electric motor always rotating in the same direction such as an electric car engine starter motor.

According to one embodiment, the stator further comprises a complementary piece of complementary shape to the magnet disposed between the support surface of the reduced portion and the inner surface of the yoke.

According to a series of features of this set that can be taken alone or in combination with each other:

the complementary piece is formed in a non-magnetized ferromagnetic material,

the complementary piece is made of material with the stator yoke,

the complementary piece is distinct from the magnet and the stator yoke, the complementary shaped piece being interposed between the magnet and the stator yoke,

According to an example of this embodiment, the complementary piece fills the space between the internal surface of the yoke and the support surface offset from the reduced portion the magnetic assembly has a constant radial thickness, along the curved profile of the 'magnet.

the complementary piece marries to the shape of the breech.

It will be understood that the object of complementary shape is intended to complete a lack of material of the magnet imbalancing the magnetic induction of the magnet on conductors of a rotor of the rotating electrical machine, when such a magnet is mounted on a stator

According to one embodiment, the contact surface is further from the axis O than the offset surface of a length greater than or equal to one third of a first thickness measured radially between the contact surface and the air gap face. .

Thus, there is material gain of at least one third on the reduced portion comprising the offset surface of the magnet thus reducing the cost of the starter.

Advantageously, the magnet can be obtained by sintering. The term "sintering" means a process for manufacturing a magnet formed from metal and rare earth powder, in particular Neodymium, Iron and / or Boron.

According to one embodiment, the magnet comprises a first radial thickness measured radially between the contact surface and the gap face and a second radial thickness measured radially between the offset surface and the air gap face and in that the second thickness is less than or equal to two-thirds of the first radial thickness measured radially between the air gap face and the support contact surface.

This therefore implies that the material gain is on the reduced portion vis-à-vis the cylinder head and thus obtain a cheaper magnet.

According to one embodiment, the inner surface of the yoke comprises a radius relative to the longitudinal axis angularly varying to be complementary to the offset surface of the magnet.

According to one embodiment, the gap face comprises a radius of curvature along an axis and in that the magnet is regularly angularly magnetized and comprises a radial magnetization vector with respect to the axis.

In one example, the axis is identical to the longitudinal axis O.

According to another embodiment, the magnet is magnetized regularly parallel to a plane comprising the mediator of an angle comprising the two edges

angular end of the magnet.

This allows to have a regular air gap with the rotor because the air gap face is cylindrical in a circle circumscribed with the rotor.

According to one embodiment, a radial thickness of the magnet measured radially between the gap face and the support face decreases towards at least one of its angular ends in a continuous manner.

The radial thickness of the magnet therefore decreases continuously. It will therefore be understood that the radial thickness of the measured magnet is not identical along its profile.

Advantageously, a first thickness measured in a portion of the magnet located at a first angular end comprising the thick support portion of the magnet is greater than a second thickness of another portion comprising the offset surface located at a second angular end. of the magnet.

The first thickness corresponds to the largest value of the thickness of the profile of the magnet and the second thickness corresponds to the smallest value of the thickness of the profile of the magnet.

By thickness of the profile of the magnet is meant a thickness measured in a section of the magnet comprising the X axis.

According to an example of this embodiment, the gap face and the support face are curved and have the same value of radius of curvature. In other words, the gap face and the support face are derived from a cylinder having the same radius value but having a center offset relative to each other.

The value of the radius of the cylinder of the gap face and the value of the radius of the cylinder of the support face therefore corresponds to the sum of the value of the outer radius of the rotor and the radial thickness of the gap.

This allows for smaller magnet cuts and thus facilitate its manufacture. Indeed by performing a cut according to the curvature, it is made both a gap face of a magnet and a bearing contact surface of another magnet without falling.

In this example, the two angular end edges of the magnet at each end of the magnet can be parallel.

Such machining result with circular arcs of the same radius offset center and parallel straight edges can be achieved such as a "tiling" (identical forms contiguous between the gap face and the contact face of the magnet next), ie without material drop, here costly, during machining.

The parallel angular end edges may further be parallel to a radius passing over the edge of the angular end. This makes it possible to have the thickest portion radially at an angular end and the portion that is less thick.

radially at its other end radially.

In addition, according to the air gap face, the center is the same center as the axis

longitudinal cylinder head and therefore the rotor. This allows for a gap that does not vary while having a support face having a thicker radial thickness on one side than on the other side.

According to another embodiment, a radial thickness of the magnet measured radially between the air gap face and the support face decreases by at least one bearing.

Thus the bearing corresponds to the difference in distance from the axis O between the support contact surface and the offset support surface.

The thickness of the magnet decreases angularly by at least one bearing. We

will understand that at least the bearing corresponds to a step along the support face for which the radial thickness of the magnet varies non-continuously.

Advantageously, at least the bearing separates a thick portion comprising the contact surface and a reduced portion comprising the reduced support surface, the thick portion and the reduced portion each having a different radial thickness. Advantageously, the reduced portion and the thick portion each have a constant thickness. The difference in distance of the longitudinal axis between the contact surface and the offset surface is related to the bearing.

When the curved profile of the magnet is segmented, it is advantageous if the thick portion is a magnet block and the reduced portion is another magnet block and the portions are butted end to end to form the profile. curve.

According to one embodiment, a radial thickness of the magnet measured radially between the air gap face and the support face decreases on the one hand continuously and, on the other hand, by at least one bearing.

For example, the bearing forms a stall between the support contact surface and the offset support surface and the thickness is reduced continuously over the reduced portion comprising the offset surface.

The smaller the thickness on the side, the less this part is subject to demagnetization and therefore the smaller the thickness can be.

In this embodiment at least the thick portion comprising the offset support surface comprises a radial thickness which decreases towards its free angular end and in that the thick portion comprising the contact surface is separated by a bearing of the reduced portion comprising the offset surface.

Advantageously, at least the bearing separates a first magnet block from a second magnet block together forming a magnet.

Advantageously, a first thickness measured at a first end of the reduced portion of the magnet profile is greater than a second thickness measured at a second free angular end of this reduced portion of the magnet profile and a first end of the thick portion of the magnet. magnet profile is greater than a second thickness measured at a second end of this thick portion of the magnet profile in contact with the first end of the reduced portion.

The first radial thickness of each portion corresponding to the largest value of the thickness of the corresponding portion and the second radial thickness measured at the second end corresponding to the smallest value of the radial thickness of the corresponding portion.

According to one variant, two opposite faces of the magnet delimiting its thickness tend to meet each other.

Advantageously, two opposite faces of the magnet delimiting its thickness meet. According to one embodiment, a radial thickness of the magnet measured radially between the air gap face and the support face is reduced regularly such that the offset surface support tends to join the air gap face.

In the following, the term "thickness of the magnet" will be understood as being a measurement made radially perpendicular to the radius of curvature of the air gap face of the magnet and the term "radial thickness of the magnet" as being a measurement made radially with respect to the longitudinal axis of the cylinder head.

According to one embodiment, the magnet comprises at least a first magnet block comprising the contact surface and a second magnet block comprising the offset surface.

Advantageously, the magnet can be segmented. In other words, the profile of the air gap face of the curved support face is formed by a succession of portions placed end to end to form this magnet.

When the profile of the magnet is segmented, it is advantageous that each portion butt to form this curved profile to a thickness that decreases continuously. Thus, it is envisaged that, to form such a curved profile, two end-to-end portions share at their end in contact a thickness of identical value.

According to one embodiment, the stator comprises at least two irregular magnets according to the various embodiments as described herein.

According to an example of this embodiment, the at least two magnets are arranged symmetrically with respect to the longitudinal axis so as to form a pair of magnetic poles.

The stator may therefore comprise at least a first pair of magnetic poles formed by two irregular magnets whose radial thickness decreases continuously and at least a second pair of magnetic poles formed by two other magnets whose radial thickness decreases continuously. .

The stator may, in a variant, therefore comprise at least a first pair of magnetic poles formed by two irregular magnets whose thickness decreases by at least one bearing and at least one second pair of magnetic poles formed by two other magnets of which thickness decreases by at least one bearing.

According to one example, the stator comprises at least a first pair of magnetic poles formed by two magnets whose thickness decreases on the one hand continuously and on the other hand by at least one bearing and at least one second The pair of magnetic poles is formed by two other magnets, the thickness of which decreases on the one hand continuously and on the other hand by at least one bearing.

According to one embodiment, the stator comprises: At least a first pair of positive magnetic poles, each of the poles being formed by an irregular magnet and

At least one second pair of negative magnetic poles, each of the poles being formed by an irregular magnet.

The invention also relates to a rotating electrical machine comprising a stator previously described with or without according to one or more embodiments and a rotor at least partly in the stator to be free to rotate about the longitudinal axis and a group of arranged brushes to allow the power supply of the rotor by switching the electric current flowing in conductors formed in notches of the rotor.

The invention also relates to a starter for a motor vehicle comprising the rotating electrical machine.

The rotor rotates a drive shaft carrying a pinion, the pinion being intended to directly drive a member of the engine of the vehicle, for example a crown also called flywheel.

The invention also relates to a rotating electrical machine comprising:

A stator comprising:

a cylindrical cylinder head along a longitudinal axis of the stator, and

a magnetized structure extending along a circumference of the stator yoke, comprising:

at least one irregular magnet based on Neodymium, iron, Boron magnetized regularly radially with respect to the longitudinal axis O, mounted against the yoke, comprising a radial thickness along the longitudinal axis O measured between an air gap surface and a support surface in contact with the cylinder head, the radial thickness varying angularly,

A rotor at least partly in the stator to be free to rotate about the longitudinal axis O comprising an air gap surface,

An air gap between the stator and the rotor comprising a radial thickness varying less than the radial thickness of the magnet.

Other features and advantages of the invention will become apparent from the description which follows, on the one hand, and from several examples of embodiments given in FIG. indicative and non-limiting with reference to the attached schematic drawings, in which:

FIG. 1 illustrates a front view of a stator and a rotor of a rotating electrical machine, the stator being equipped with magnetic assemblies according to a first embodiment,

FIG. 2 illustrates a front view of a stator according to a second embodiment, FIG. 3 illustrates a front view of a stator according to a third embodiment, FIG. 4 schematically illustrates a front view of a example of a stator of the embodiment of FIG.

FIG. 5 schematically illustrates a front view of another example of a stator of the embodiment of FIG. 2,

FIG. 6 schematically illustrates a front view of another example of a stator of the embodiment of FIG. 2,

FIG. 7 schematically illustrates a front view of another example of a stator of the embodiment of FIG. 2,

FIG. 8 schematically illustrates a front view of another example of a stator of the embodiment of FIG. 1,

FIG. 9 schematically illustrates an explanation view of a method of cutting a magnet bar mounted in the example of the stator of FIG. 8,

As illustrated in Figure 1, there is shown a stator 1, or inductor, and a rotor 2, or induced, of a rotating electrical machine. Such a rotating electrical machine can be a DC machine equipping a starter for a motor vehicle.

The stator 1 comprising a cylinder-shaped cylinder head 10 along an axis

longitudinal axis O of the stator 1 comprising an inner surface. A magnetic structure 11 is disposed in the yoke 10 to extend along a circumference 11C of the yoke 10 of the stator 1. According to the invention, the magnetic structure 11 comprises two pairs of magnetic assemblies 3. Each pair of magnetic assemblies 3 form a pair of magnetic poles.

The rotor 2 is configured to be rotated about the longitudinal axis O of the stator 1. The rotor 2 comprises notches 20 in which are disposed conductors 21 forming the winding of such a rotating electrical machine. These conductors 21 are intended to be supplied with direct current by a battery of the vehicle via a contactor of the starter. Each magnetic assembly 3 comprises an irregular magnet 4. Such a magnetic assembly 3 may also comprise a complementary piece 5 of complementary shape to the irregular magnet 4 and disposed on the irregular magnet 4, radially outside the irregular magnet 4 with respect to the longitudinal axis O.

The complementary piece 5 is therefore located between the inner surface of the yoke 10 and a support face 40 of the irregular magnet 4 facing the yoke. The complementary piece is at least located between a surface of the magnet called in the following surface offset from the support face 40.

Each irregular magnet 4 of the magnetic assemblies 3 is an irregular magnet 4 based on Neodymium, Iron, Boron. The irregular magnet 4 comprises a curved profile P along a radius R from which can be measured a radial thickness E of the irregular magnet 4, that is to say in a radius of the longitudinal axis O. This thickness varies along the angular profile of the irregular magnet 4. The radial thickness is in other words then measured along a line D passing through the longitudinal axis O.

A curved line L symmetrically sharing the angular profile of the magnet of each irregular magnet 4 separates a North N polarity of the irregular magnet 4 from a South polarity S of the irregular magnet 4. In the example illustrated, the radius R of each irregular magnet 4 is inscribed in a circle C delimiting a cylinder of axis

longitudinal O in which an air gap face 41 of the irregular magnet 4 extends.

The irregular magnet 4 and its complementary shaped part 5 of a magnetic assembly 3 are arranged so that the magnetic assembly 3 has a constant thickness E 'measured along the radius R along the angular profile of the irregular magnet

4

The complementary shaped part 5 is formed of a non-magnetized ferromagnetic material and may be made of material with the yoke 10 of the stator 1 to form a one-piece assembly. However, the invention is not limited to this configuration and it may be provided that the complementary shaped part 5 is attached to the yoke 10 of the stator 1. In other words, the complementary shaped part 5 can be distinct from the irregular magnet 4 and the yoke 10 of the stator 1 and is interposed between the irregular magnet 4 and the yoke 10 of the stator 1. When the complementary-shaped parts 5 are attached to the yoke 10 of the stator 1, these parts 5 can be mounted on this cylinder head 10 by gluing or stapling. In the same way, each irregular magnet 4 can be attached to its complementary shape piece by gluing or stapling.

The sets of each pair of magnetic assemblies 3 are arranged

symmetrically with respect to the longitudinal axis O so as to form a pair of magnetic poles. More particularly, it will be understood that the irregular magnets 4 of each pair of magnetic assemblies 3 are arranged symmetrically with respect to the longitudinal axis O so as to form a pair of magnetic poles Pi, P2, namely a first magnetic pole Pi and a second magnetic pole P2. For each pair of magnetic pole Pi, P2, a first magnetic pole Pi of a first irregular magnet 4 is a north pole N oriented radially with respect to the longitudinal axis O and facing the conductors 21 of the rotor 2 and another pole magnetic P2 of a second irregular magnet 4 is a south pole S oriented radially relative to the longitudinal axis O and facing the conductors 21.

In this example of this first embodiment illustrated in FIG. 1, the thickness E of the irregular irregular magnet 4 decreases continuously so that the air gap face 41 opposite to the support face 40 of the magnet irregular 4 delimiting its thickness E meet.

The magnet therefore comprises a thick portion 43 comprising an angular end edge 6 extending parallel to the axis O and a reduced portion 42 comprising an angular end edge 7 extending parallel to the axis O.

The support face 40 includes an offset surface 402 located in the reduced portion 42 and a contact surface 403 located in the thick portion 43.

The contact surface 403 is therefore further from the axis O than the offset surface 402.

It will be understood that the thickness E of the irregular magnet 4 measured

perpendicular to the radius R is irregular, that is to say is not identical along the angular profile of the irregular magnet 4.

Thus, a first thickness El measured at a first end 6 of the angular profile of the magnet is greater than a second thickness E2 measured at a second end 7 of the angular profile of the magnet. The first thickness E1 corresponds to the largest value of the thickness E of the angular profile of the magnet and the second thickness E2 corresponds to the smallest value of the thickness E of the angular profile of the magnet.

We will now describe the operation of the engine.

Under each inductive pole (N or S), of homogeneous sign: positive sign or negative sign with regard to the induction that it produces in the gap, the magnetic reaction of armature consists in particular in producing a field: for half of the same sign, and half of opposite sign when conductors 21 of the rotor 2 are supplied with direct current.

For each magnetic pole Pi, P2, the thick portion 43 of the irregular magnet 4 of the magnetic pole Pi, P2 is therefore subjected to an armature magnetic field of the rotor 2 in the opposite direction in the direction of this thick portion 43 of the irregular magnet 4 vis-à-vis of the rotor. This thick portion is calibrated having a thickness sufficient to not be demagnetized by this armature reaction.

The reduced portion 42 of the irregular magnet 4 of the same magnetic pole Pi, P2 is subjected to a rotor armature magnetic field 2 of the same sign at this reduced portion 42 of the irregular magnet 4. There is therefore no no risk of demagnetization for this reduced portion.

The reduced portion may therefore comprise a radial thickness such that if it undergoes a magnetic field armature reaction opposite to the magnet vis-à-vis the rotor, it may undergo demagnetization.

It will then be understood that for each irregular magnet 4, the thickness E measured along the radius R of the irregular magnet 4 is on the side of the thick portion 43 of the irregular magnet 4 whose magnetic field of armature is of opposite sign. greater than the side of the reduced portion 42 of the irregular magnet 4, the magnetic field armature is the same sign.

The sizing of the magnets 4 is then optimized so that it is possible to reduce the weight and the volume of the magnets while allowing the formation of the required engine torque and without loss of performance.

As illustrated in FIG. 2, there is shown an example of a second embodiment of the magnetic assemblies 3. In the same way, the complementary shaped parts 5 and the magnets 4 are of complementary shape to each other. 'other. In this second embodiment, the thickness E of each irregular magnet 4 decreases by two bearings 44, 45. The two bearings 44, 45 separate three portions 46-48 of the irregular magnet 4, namely a thick portion 46, an intermediate portion 47 and a reduced portion 48. Each bearing 44, 45 corresponds to a step along the angular profile of the magnet for which the thickness E of the irregular magnet 4 varies non-continuously. In the example shown, the thick portion 46 and the intermediate portion 47 are separated by a first bearing 44, and the intermediate portion 47 and the reduced portion 48 are separated by a second bearing 45. Each portion 46-48 has a thickness E constant. The thick portion 46 is of thickness and greater than the thickness E2 of the intermediate portion 47 and the intermediate portion 47 has a thickness E2 greater than the thickness E3 of the reduced portion 48. In other words, the portion 46, the intermediate portion 47 and reduced portion 48 are cascaded relative to each other.

In this example, the complementary piece 5 is in contact with the offset surface 402 of the reduced portion 48 and an intermediate surface of the intermediate portion 47. The contact surface 403 is therefore in direct contact with the cylinder head in this example.

Of course, as in the previous embodiment, the thick portion of the magnet is located in the stator of the angular side where the armature reaction causing a magnetic field of opposite sign to that of the magnet and thus the reduced portion 48 is found on the angular side where the magnetic field is of the same sign.

As illustrated in FIG. 3, an example of a third embodiment of the magnetic assemblies 3 is shown. In the same way, the complementary shaped parts 5 and the magnets 4 are of complementary shape to each other. 'other. Similarly to the second embodiment, the two bearings 44, 45 separate three portions 46-48 of the irregular magnet 4, namely a thick portion 46, an intermediate portion 47 and a reduced portion 48 and the thick portion 46 and the intermediate portion 47 are separated by a first bearing 44, and the intermediate portion 47 and the reduced portion 48 are separated by a second bearing 45.

Unlike the second embodiment, in this third embodiment, the thickness E of the irregular magnet 4 decreases, on the one hand, continuously and, on the other hand, by two bearings 44, 45. Thus, each portion 46-48 has a thickness E which decreases continuously. For each portion, 46-48 a first thickness And measured at a first end 6 of the portion of the angular profile of the magnet is greater than a second thickness E2 measured at a second end 7 of this portion 46-48 of the angular profile of the magnet. The first thickness And each portion 46-48 corresponding to the largest value of the thickness E of the corresponding portion 46-48 of the angular profile of the magnet and the second thickness E2 measured at the second end 7 corresponding to the largest small value of the thickness E of the corresponding portion 46-48 of the angular profile of the magnet.

Of course, another example of this embodiment could only include a single bearing and therefore the magnet would comprise only the thick portion and the reduced portion or could have more than two bearings.

In common with each of the embodiments, it has been found that the angular profile of the irregular magnet 4 of the invention according to an angular aperture Q and an angular length Li of the angular profile of the magnet are parameters that can influence the determination of the motor torque resulting from the thickness variation E of the angular profile of the magnet of the magnets 4.

FIG. 4 represents a block diagram of a portion of a stator 1 according to another example of the embodiment comprising a yoke represented schematically by a portion of a circle, and a magnetic assembly 3. Of course, the stator 1 comprises at least two magnetic sets 3 but only one has been shown.

In this example, there is only one bearing 44 contrary to the example of Figure 2 comprising two bearings 44, 45. In addition, in this example, there is a magnet block of reduced thickness and a thick magnet block having a radial thickness greater than the thickness of the magnet block of reduced thickness. The magnet block of reduced thickness and the thick magnet block forms the irregular magnet. The two blocks of magnets are thus stacked angularly. The magnet block of reduced thickness forms the reduced portion 48 of the magnet and the thickness block thus forms the thick portion 46 of the magnet 4.

Of course the two magnet blocks are magnetized in the same radial direction, that is to say for example the south against the cylinder head and the north opposite the air gap. One thus means irregular magnet only one block of magnet or several having their polarity in the same direction to form a pole of the stator.

For example, in this embodiment, if the rotor rotates clockwise, the magnetic field of the armature reaction having a direction opposite to the magnet is located on the right side in FIG. screw of the thick portion comprising the contact surface of the support face.

The gap face is thus formed by the magnet block of reduced thickness and the thick magnet block.

There is no intermediate portion in this example since there is no second stage but could have one, in that the thick portion would be either another magnet block or a portion of the block. thick-thick magnet or a portion of the magnet block of reduced thickness.

In this example, the complementary piece 5 is in contact with the offset surface 402 and a radial surface of the thick portion 46.

FIG. 5 represents another example of this second embodiment, in which the irregular magnet 4 is formed by a single block.

In this example, the complementary part 5 further comprises a shunt portion 51 extending towards the X axis being in contact with a radial surface of the reduced portion 48. This portion 51 therefore comprises a gap face extending the face. gap 41 of the irregular magnet 4.

This shunt portion 51 can also be further mounted on the examples of the embodiments described above.

FIG. 6 represents the example of FIG. 5 except that the magnet 4 is in two blocks of magnets angularly stacked such as that represented in FIG. 4.

Fig. 7 shows another example of this embodiment, wherein the irregular magnet 4 comprises two radially stacked magnet blocks. In this example, the magnet 4 comprises a complementary piece 5 with a shunt portion as in the example of Figure 5 or 6 but could of course have a complementary piece without this shunt portion.

In this example, the irregular magnet 4 therefore comprises an air gap magnet block and a contact magnet block. The contact magnet block comprises the contact surface 403 of the support face 40 of the magnet block 4.

The gap magnet block includes the gap face 41. The gap magnet block is angularly longer than the contact magnet block. This additional length forms the reduced portion 48 of the irregular magnet 4 thus comprising the offset surface 402. The thick portion of the irregular magnet 4 is therefore both formed by the gap magnet block and the block of contact magnet.

Figure 8 shows another example of the first embodiment. In this example, the air gap face in the form of a portion of a cylinder of axis O along a radius R and the support face comprises in the form of a portion of a cylinder Y axis offset radially towards the magnet 4 along the same radius R.

The air gap face 41 and the support face 40 are therefore curved and have the same value of radius R of curvature. In other words, the air gap face 41 and the support face 40 come from a cylinder of the same radius. The center of the cylinder of the air gap face therefore has its center offset from the center of the cylinder comprising the support face.

Figure 9 schematically shows a rectangular magnet block 400 and a cylindrical cutter shown schematically partially by a circular arc in four cutting positions Bi, B2, B3, B4.

In this example, the cutting tool moves radially relative to its axis and comes to cut the magnet block by moving axially and turning to make the cut.

Cutting at the position Bi produces a first drop of the magnet block not shown and the gap face of an irregular magnet A to be positioned in the cylinder head 10 of the example of FIG. 8. Cutout at the B2 position forms both the support face of the magnet A and the gap face of a magnet A '. The cut at the position B3 forms both the support face of the magnet A 'and the gap face of a magnet A ".

The cut at the position B4 forms both the support face of the magnet A "and the air gap face of another magnet not shown cut out in FIG. 9.

In this example, the two angular end edges 6 and 7 of the magnet at each end of the magnet are parallel.

Such a machining result with circular arcs of the same radius offset center and parallel straight edges can be achieved such as a "paving" (identical forms joined between the gap face and the contact face of the next magnet), that is to say without material drop, here expensive, during machining.

Of course, there is a fall at the beginning and the end of the block A but no fall between each magnet formed.

The stator further comprises a complementary part 5 which can of course also comprise a shunt portion as in the previous examples.

Of course, the features, variants and different embodiments of the invention may be associated with each other, in various combinations, to the extent that they are not incompatible or exclusive of each other. In particular, it will be possible to imagine variants of the invention comprising only a selection of characteristics described subsequently in isolation from the other characteristics described, if this selection of

characteristics is sufficient to confer a technical advantage or to differentiate the invention from the state of the art.

Claims

i) Stator (i) for equipping a rotating electrical machine, the stator (1) comprising:

A cylinder-shaped yoke (10) along a longitudinal axis (O) of the stator (1) comprising an internal surface, and

At least one irregular magnet (4) based on neodymium, iron, boron regularly magnetized radially with respect to an axis towards the longitudinal axis (O) or parallel to a plane comprising the axis and passing through the magnet, mounted in the yoke (10) against the inner surface of the yoke (10), the magnet (4) comprising:

an air gap face (41) facing the longitudinal axis (O) and

a support face (40) opposite to the air gap face (41), the support face being in contact with the internal surface of the yoke (10) and comprising:

i a contact surface (403) of a thick portion of the magnet and ii an offset surface (402) of a reduced portion of the magnet, characterized in that the contact surface (403) is further away from the longitudinal axis (O) as the offset surface (402).

2) Stator according to claim 1, wherein the contact surface (403) is further from the axis O than the offset surface (402) of a length (I) greater than or equal to one third of a first thickness (And) of the thick portion (43, 46) measured radially between the contact surface (403) and the gap face.

3) Stator according to claim 1 or 2, wherein the magnet comprises a first thickness (Et) measured radially between the contact surface (403) and the gap face and a second thickness (E2) measured radially between the offset surface (402) and the air gap face and in that the second thickness (E2) is less than or equal to two-thirds of the first radial thickness (Et) measured radially between the air gap face (41) and the surface support contact (40). 4) Stator according to one of claims 1 to 3 wherein the inner surface of the yoke (10) comprises a radius R with respect to the longitudinal axis O angularly varying to be complementary with the offset surface (402) of the irregular magnet 4.

5) Stator according to any one of the preceding claims, wherein the air gap face (41) comprises a radius of curvature along a longitudinal axis O and in that the magnet (4) is regularly angular magnetized and comprises a vector radial magnetization with respect to the longitudinal axis O.

6) Stator according to any one of the preceding claims, wherein the gap face (41) and the contact surface (403) are curved and have the same value of radius of curvature.

7) Stator according to any one of the preceding claims, wherein a thickness (E) of the magnet (4) measured radially between the air gap face (41) and the support face (40) decreases towards at least one of its angular ends in a continuous way.

8) Stator according to any one of the preceding claims, characterized in that a thickness (E) of the magnet (4) measured radially between the air gap face (41) and the support face (40). decreases by at least one level (44, 45) ·

9) Stator according to any one of the preceding claims, characterized in that a thickness (E) of the magnet (4) measured radially between the air gap face (41) and the support face (40) decreases, d on the one hand, continuously and on the other hand by at least one bearing (44, 45).

10) Stator according to any one of the preceding claims, characterized in that the air gap face (41) and the support face (40) tend to meet. 11) Stator according to any one of the preceding claims, characterized in that the magnet (4) comprises at least a first magnet block (4) comprising the contact surface (403) and a second magnet block ( 4) comprising the offset surface (402).

12) Stator (2) according to one of the preceding claims, comprising

At least a first pair of positive magnetic poles (Pi, P2), each of the poles being formed by an irregular magnet (4) and

At least a second pair of negative magnetic poles (Pi, P2), each of the poles being formed by an irregular magnet (4).

13) A rotary electric machine comprising a stator (1) according to any one of the preceding claims and a rotor (2) at least partly in the stator (1) to be free to rotate about the longitudinal axis (O) and a group of brushes arranged to allow the power supply of the rotor (2) by switching the electric current flowing in conductors (21) formed in notches (20) of the rotor (2). 14) Starter for a motor vehicle comprising a rotary electrical machine according to the preceding claim.