WO2021123528A1

WO2021123528A1 - Rotor of a rotary electric machine

Info

Publication number: WO2021123528A1
Application number: PCT/FR2020/052179
Authority: WO
Inventors: Samuel KOECHLIN
Original assignee: Nidec Psa Emotors
Priority date: 2019-12-20
Filing date: 2020-11-26
Publication date: 2021-06-24
Also published as: FR3105636A1; FR3105636B1

Abstract

Disclosed is a rotor (1) of an electric machine, said rotor rotating about an axis of rotation (X) and comprising: - a shaft (5) arranged on the axis of rotation (X), - a rotor mass (3) that extends along the axis of rotation (X) and is arranged around the shaft, the rotor having at least one groove (12) formed in the shaft (5) and at least one tab (14) formed on the rotor mass (3), the tab interacting with the groove for transmitting torque between the rotor mass and the shaft, the at least one tab (14) being planed when the rotor mass (3) is inserted onto the shaft (5).

Description

Title: ROTARY ELECTRIC MACHINE ROTOR

The present invention claims the priority of the French application 1915138 filed on December 20, 2019, the content of which (text, drawings and claims) is incorporated here by reference.

The present invention relates to the field of rotating electrical machines and more particularly the rotors of such machines. The invention relates in particular to the mounting of the rotor on a shaft of the machine, and in particular to the connection between G shaft and a rotor mass of the rotor.

Technical area

The invention relates more particularly to synchronous or asynchronous machines with alternating current. It relates in particular to traction or propulsion machines for electric motor vehicles (Battery Electric Vehicle) and / or hybrids (Hybrid Electric Vehicle - Plug-in Hybrid Electric Vehicle), such as passenger cars, vans, trucks or buses. The invention also applies to rotating electrical machines for industrial and / or energy production applications, in particular naval, aeronautical or wind turbines.

Prior art

It is known to produce a rotor comprising a connection between the shaft and the rest of the rotor. In EP 2 549624, this connection comprises a radial deformation of the teeth. In JP 4602784 B2, we have a deformation of the sheets in the axis of the machine.

However, in the case of machines intended to run at high rotational speeds, there is a risk that the rotor mass of the rotor will stretch under the effect of the speed, also known as centrifugal expansion. If the rotor mass is clamped onto the machine shaft, then the tightening must be increased to ensure sufficient contact pressure at high speed. Too high press-fit forces can in some cases lead to shaft deformation, and out-of-plane sheet deformation can manifest as irregular axial deformations of the rotor mass.

There may also be greater electromagnetic interference, and a greater risk of sudden detachment, in the event of too high a torque or of shocks. There is therefore a need to benefit from a rotor of a rotating electric machine allowing easy and less expensive installation, and simpler and safer use.

Summary of the invention

The invention aims to meet this need and it achieves it, according to one of its aspects, by means of an electric machine rotor, rotating around an axis of rotation X, the rotor comprising:

- a shaft arranged on the axis of rotation X,

a rotor mass extending along the axis of rotation X and arranged around the shaft, the rotor comprising at least one groove formed in the shaft and at least one tongue formed on the rotor mass, the tongue cooperating with the groove for the transmission of torque between the rotor mass and the shaft, the tongue or tongues undergoing planing during the insertion of the rotor mass on the shaft.

The torque transmission means allow the rotational drive of the rotor mass by the shaft or of the shaft by the rotor mass. The cooperation of the tongue (s) and the groove (s) makes it possible to make the shaft and the rotor mass integral in rotation.

The planing of the tongues can allow the existence of a pre-stress in the means of transmission of torque, which favors the solidity of the connection between the shaft and the rotor mass. This avoids the risk of sudden detachment, even with high torque. The tab (s) may deform during use of the rotor, but without inducing play with the shaft. Very efficient torque transmission is ensured whatever the speed of rotation, without excessive pre-stress on the rotor mass.

The tongue may preferably be, before the insertion of the rotor mass on the shaft, a little wider than the groove. During insertion, the front edge of the groove cuts the tongue to the exact width of the groove.

The implementation of the invention makes it possible to avoid the need for very precise sizing and high-precision machining, thanks to the planing of the tongues. The absence of play between the rotor mass and the shaft nevertheless allows the necessary torque reversals. The cost is therefore reduced. Judicious sizing guarantees torque transmission while limiting the assembly effort. Disclosure of the invention

In one embodiment, the shaft may be made of a material with a hardness greater than 400 HV, better still greater than 500 HV, or even greater than 600 HV, being for example a hard steel with a hardness greater than 650 HV.

In one embodiment, the rotor mass can be made from a material with a hardness less than 300 HV, better still less than 250 HV, or even less than 220 HV, being for example of the order of 200 HV.

In one embodiment, the groove or grooves have two lateral sides, each tongue resting on the two sides of the groove.

Each tongue can cooperate with a groove. As a variant, two or more tongues can cooperate with the same groove. The rotor may have a single groove, with which two tongues cooperate. In this case, the two tongues can fit into the same groove, each pressing against a side of the groove.

The rotor may have several grooves and several tongues, for example an even number of tongues or an odd number of tongues, each tongue being able to cooperate with a groove or two tongues cooperating with a groove. Each groove can cooperate with one or more tongues, in particular one or two tongues.

In one embodiment, the rotor has a groove and a tongue.

As a variant, the rotor may include at least two grooves and two tongues, each tongue cooperating with a groove. The two tongues and the two grooves can be respectively symmetrical to each other with respect to a plane P of symmetry containing G axis of rotation X of the rotor. The rotor may include an even number of tongues, each tongue cooperating with a groove, or even two tongues cooperating with the same groove, or even an even number of grooves and tongues, each tongue cooperating with a single groove. As a variant, the rotor may have an odd number of tongues, each tongue cooperating for example with a groove.

As a variant, the rotor has four grooves and four tongues, each tongue cooperating with a groove. As a further variant, the rotor has three grooves and three tongues, each tongue cooperating with a groove.

The tongue can be formed on the rotor mass, and the groove in the shaft. This configuration is advantageous in particular when the rotor mass can be deformed more easily than the shaft, insofar as the tongue undergoes planing. It is by example the case when the rotor mass is formed from a stack of sheets. Apart from the groove (s), the shaft has a circular cross section. The tongue is preferably formed in a central bore of the rotor mass intended to receive the rotor shaft. The cutting of the tab (s) can be promoted by the lamination of the rotor mass, each sheet of the rotor mass being able to shear independently of its neighbors.

In an alternative embodiment, the tongue is symmetrical with respect to a plane containing the axis of rotation. The tongue can also be symmetrical with respect to the groove. Thanks to this symmetry, the tongue is planed in a balanced manner when it is inserted into the groove. In cross section, the tongue may include a first lateral edge intended to come into contact with the groove and a second lateral edge also intended to be in contact with the groove. These two side edges can be substantially rectilinear, or even entirely rectilinear, or convex. They can extend substantially parallel to a radial axis of the rotor, or even entirely parallel to a radial axis of the rotor. In cross section, the tongue may have a third circumferential edge which may, before insertion of the shaft into the rotor mass, extend substantially circumferentially. This third circumferential edge is not intended to be in contact with the groove. Such a configuration of the tongue makes it possible to overcome the problems of dimensional tolerances.

Furthermore, the sizing of the groove or grooves can also overcome problems of dimensional tolerances. A large tolerance of their sizing is possible. The groove or grooves can be produced by simple milling.

The groove may have a sharp entry edge, which helps promote shearing of the tongue.

The planing of the tongue can take place in a plane perpendicular to the axis of rotation X of the rotor. The tongue is planed in a circumferential direction. Essentially, the tongue does not deform radially or axially. Chips from planing can be discharged at the end of the shaft in the axial direction.

The tongue or tongues may include at their base at least one lateral rib, or even two lateral ribs on either side. The rib or ribs extend longitudinally. The rib or ribs allow easy planing of the tongue. They also make it possible to avoid any possible contact between the rotor mass and the shaft, in particular one or more ridges of the shaft at the level of the groove.

In one embodiment, the rotor may include a groove which, in a first given cross section of the rotor, does not cooperate with a tongue. A tongue can cooperate with said groove in a second cross section of the rotor remote from the first cross section. The rotor may for example comprise three grooves and two tongues, each tongue cooperating with a groove and a groove remaining devoid of tongue, in a given cross section.

The groove (s) and tongue (s) can be configured so as to allow torque transmission in both directions, regardless of the direction of rotation of the rotor, both with positive torque, in the event of acceleration, and with a negative torque, in the event of braking, by virtue of contact zones between the groove or grooves and the tongues which are opposed in the orthoradial direction.

The groove or grooves may have non-parallel flanks, for example in the case of a flared groove section. The groove sides may or may not be rectilinear. The groove flanks may for example have a convex shape, for example similar to that of a gear tooth flank.

In one embodiment, the two tongues and the two grooves may be respectively symmetrical to each other with respect to a plane of symmetry containing the axis of rotation. Such a symmetrical configuration allows torque transmission in both directions, regardless of the direction of rotation of the rotor, both with positive torque, in the event of acceleration, and with negative torque, in the event of braking.

Sheets

The rotor mass is preferably formed from a stack of sheets, in particular sheets that are all substantially identical, namely at least identical on the side of the shaft. The sheets are magnetic. The plates of the rotor mass can all be identical on the side of their cooperation with the shaft. In particular, the rotor mass may not be massive. The tabs are made in one piece with the sheets.

At least one sheet, better still all sheets, can be such that the stack of sheets includes at least one sheet offset angularly around the axis of rotation with respect to another sheet, the sheets being offset by an angle given with respect to each other, for example at an angle of 90 ° or 120 ° or 180 °. In one embodiment, a sheet may include a single tongue cooperating with a single groove in the shaft, the rotor mass comprising sheets arranged in one direction and sheets turned in the other direction.

The rotor mass sheet stack may have sheets arranged in one direction and sheets turned in the other direction. Sheets can be turned in bundles, the rotor mass sheet stack comprising alternating bundles of sheets arranged in one direction and bundles of sheets turned in the other direction. A more homogeneous distribution of the stresses in the rotor is thus obtained. The performance of the machine is improved, especially in terms of vibrations, noise, and torque ripples.

At least one sheet, better still all sheets, can be configured such that the stack of sheets has at least one sheet offset angularly about the axis of rotation relative to another sheet.

Thus, with a single form of sheet it is possible to obtain several different angular positions. For a sheet metal shape, one can have several different angular positions possible, this number being less than or equal to twice the number of grooves, and also being less than or equal to twice the number of cyclic patterns of the rotor. The term “cyclic pattern” is understood to mean the geometric or magnetic characteristics which are reproduced when one turns around the rotor, for example the pairs of poles or the notches.

A sheet can be angularly offset as much as a cyclic pattern, so as to obtain as many angular positions as there are grooves, for example two, three or four times, provided that the number of grooves is a sub-multiple of the number of cyclic patterns.

You can also turn a sheet 180 ° around an axis of diametral chosen perpendicular to the axis of rotation of the rotor, so as to arrange it in the other direction, as mentioned above. Thus, one and the same sheet can be used to produce up to twice the number of cyclic patterns, and the number of grooves to be machined in the shaft is reduced.

In an exemplary embodiment, a four-pole rotor has two cyclic patterns. We can therefore have four different positions with one and the same sheet metal shape. Two grooves and a tongue allow these four positions to be achieved. In another exemplary embodiment, a six-pole rotor has three cyclic patterns. We can therefore have six different positions with one and the same sheet metal shape. Three grooves and a tongue allow these six positions to be achieved.

Rotor

The rotor may include permanent magnets, in particular with surface or buried magnets. The rotor can be in flux concentration. It can include one or more layers of magnets arranged in I, U or V.

Alternatively, it may be a wound or squirrel cage rotor, or a variable reluctance rotor.

The number of poles P at the rotor is for example between 4 and 48, being for example 4, 6, 8, 10 or 12.

The diameter of the rotor may be less than 400 mm, better still less than 300 mm, and greater than 50 mm, better still greater than 70 mm, being for example between 100 and 200 mm.

The housings of the permanent magnets can be made entirely by cutting from the sheets. Each sheet of the stack of sheets can be made in one piece.

Each sheet is, for example, cut from a sheet of magnetic steel or containing magnetic steel, for example steel 0.1 to 1.5 mm thick. The sheets can be coated with an electrically insulating varnish on their opposite sides before they are assembled in the stack. Electrical insulation can also be obtained by heat treatment of the sheets, if necessary.

Alternatively, the rotor mass can be made from compacted or agglomerated magnetic powder.

The rotor magnetic mass may have salient poles. The poles can be integral with the rest of the rotor mass, or attached to it.

The shaft can be made of a magnetic material, which advantageously reduces the risk of saturation in the rotor mass and improves the electromagnetic performance of the rotor.

As a variant, the rotor comprises a non-magnetic shaft on which the rotor mass is placed. The shaft can be made at least in part from a material from the following list, which is not limiting: steel, stainless steel, titanium or any other non-magnetic material. The rotor mass can in one embodiment be placed directly on the non-magnetic shaft, for example without an intermediate rim. As a variant, in particular in the case where the shaft is not non-magnetic, the rotor may include a rim surrounding the shaft of the rotor and coming to bear on the latter.

The rotor mass may have one or more holes to lighten the rotor, allow its balancing or for the assembly of the rotor plates constituting it. Holes can allow the passage of tie rods now integral with each other the sheets.

The sheets can be cut in a tool one after the other. They can be stacked and clipped or glued into the tool, in complete packages or sub-packages. The sheets can be snapped onto each other. Alternatively, the sheet bundle can be stacked and welded outside the tool.

The rotor mass may have an outer contour which is circular or multilobed, a multilobed shape which may be useful, for example, for reducing torque ripples or current or voltage harmonics.

The rotor may or may not be cantilevered relative to the bearings used to guide the shaft.

The rotor can be produced in several sections aligned in the axial direction, for example at least two sections. Each of the sections can be angularly offset with respect to the adjacent pieces (“step skew” in English).

In this configuration, there can be a groove which, in a first given cross section of the rotor, does not cooperate with a tongue, and which in a second cross section of the rotor remote from the first cross section, cooperates with one or more tongues.

The first and second cross sections belong to sections of the rotor which are angularly offset from adjacent pieces.

The rotor may for example comprise three grooves and two tongues, each tongue cooperating with a groove and a groove remaining devoid of tongue, in a given cross section.

The grooves of a rotor can all have the same width or angular extent. As a variant, they may include two identical grooves, and a third groove having a different angular extent or width, for example greater. This configuration can also make it possible to obtain a certain angular offset of the mass. rotor with respect to the shaft, depending on the sections and on the cooperation or not of one or more tongues with the groove of different angular extent or width, for example greater.

Machine and stator

Another subject of the invention is a rotating electrical machine, comprising a rotor as defined above. The machine can be used as a motor or as a generator. The machine can be reluctance. It can constitute a synchronous motor or as a variant a synchronous generator. As a further variant, it constitutes an asynchronous machine.

The maximum speed of rotation of the machine can be high, being for example greater than 10,000 rpm, better still greater than 12,000 rpm, being for example of the order of 14,000 rpm at 15,000 rpm or even 20,000 rpm or 25,000 rpm. The maximum speed of rotation of the machine may be less than 100,000 rpm, or even 60,000 rpm, or even less than 40,000 rpm, better still less than 30,000 rpm.

The machine may have a single inner rotor or, alternatively, an inner rotor and an outer rotor, arranged radially on either side of the stator and coupled in rotation.

The machine can be inserted alone in a housing or inserted in a gearbox housing. In this case, it is inserted in a housing which also houses a gearbox.

The machine has a stator. The latter comprises teeth defining notches between them. The stator may comprise electrical conductors, at least some of the electrical conductors, or even a majority of the electrical conductors, possibly being in the shape of a U or I pin.

The notches can be at least partially closed. A partially closed notch makes it possible to provide an opening at the level of the air gap, which can be used, for example, for the installation of the electrical conductors for filling the notch. A partially closed notch is in particular formed between two teeth which each have pole shoes at their free end, which close the notch at least in part. Alternatively, the notches can be completely closed. The term “fully closed notch” denotes notches which are not open radially towards the air gap.

In one embodiment, at least one notch, or even each notch, can be continuously closed on the side of the air gap by a bridge of material formed in one piece with the teeth defining the notch. All the notches can be closed on the side of the air gap by material bridges closing the notches. The bridges of material may have come in one piece with the teeth defining the notch. The stator mass is then devoid of any cutout between the teeth and the bridges of material closing the notches, and the notches are then continuously closed on the side of the air gap by the bridges of material coming in one piece with the teeth defining the notch.

In addition, the notches can also be closed on the side opposite the air gap by an attached cylinder head or integrally with the teeth. The notches are then not open radially outwards. The stator mass may be without a cutout between the teeth and the cylinder head.

In one embodiment, each of the notches has a continuously closed contour. By "continuously closed" is meant that the notches have a continuous closed contour when viewed in cross section, taken perpendicular to the axis of rotation of the machine. You can go all the way around the notch without encountering a cutout in the stator mass.

The stator mass can be produced by stacking magnetic sheets, the notches being formed by cutting the sheets. The stator mass can alternatively be produced by cutting from a mass of sintered or agglomerated magnetic powder. The closing of the notches on the side of the air gap is obtained by bridges of material coming in one piece with the rest of the sheets or the block forming the stator mass.

The stator may not be fitted with attached magnetic wedges for closing the notches. This eliminates the risk of accidental detachment of these wedges.

The stator may include coils distributed in a distributed manner in the notches, in particular having electrical conductors arranged in a row in the notches. The term “distributed” is understood to mean that at least one of the coils passes successively through two non-adjacent notches. The electrical conductors may not be arranged in the notches in bulk but in an orderly manner. They are stacked in the notches in a non-random manner, being for example arranged in rows of aligned electrical conductors. The stack of electrical conductors is for example a stack in a hexagonal network in the case of electrical conductors of circular cross section.

The stator may include electrical conductors housed in the notches. At least electrical conductors, see a majority of electrical conductors, can be in the shape of pins, in particular U or I. The pin may be U-shaped ("U-pin" in English) or straight, being I-shaped ("I-pin" in English).

Each electrical conductor can have one or more strands ("wire" or "strand" in English). By "strand" we mean the most basic unit for electrical conduction. A strand can be of round cross section, we can then speak of "wire", or flat. The flat strands can be shaped into pins, for example a U or an I. Each strand is coated with an insulating enamel.

The electrical conductors can form a single coil, in particular whole or fractional. By "single winding" is meant that the electrical conductors are electrically connected together in the stator, and that the connections between the phases are made in the stator, and not outside the stator, for example in a terminal box. . A coil is made up of a number of phases m spatially shifted in such a way that when supplied by a multi-phase current system, they produce a rotating field. The winding can be whole or fractional. The winding can be full in pitch with or without shortening, or in a fractional variant. In one embodiment, the electrical conductors form a fractional winding, in particular with a shortened pitch.

The winding can be wavy. The electrical conductors can be placed in series in a so-called corrugated winding. The term “corrugated winding” is understood to mean a winding in which the electrical conductors of the same phase and of the same pole are electrically connected to one another so that, for a winding path, the electric current of the phase circulates in the electrical conductors rotating around the axis of rotation of the machine, always in one direction. For a winding track, the electrical conductors of the same phase and the same pole do not overlap when observed perpendicular to the axis of rotation of the machine. The winding may have a single winding path or several winding paths. In an "electrical conductor" flows the current of the same phase by winding. The term “winding path” is understood to mean all the electrical conductors of the machine which are traversed by the same electric current of the same phase. These electrical conductors can be connected to each other in series or in parallel or in series-parallel. In the case where there is only one channel, the electrical conductors are connected in series. In the case where there are several channels, the electrical conductors of each channel are connected in series, and the channels are connected in parallel.

The electrical conductors can thus form a distributed coil. The winding may not be focused or wound onto tooth.

In an alternative embodiment, the stator has a concentrated winding. The stator may include teeth and coils arranged on the teeth. The stator can thus be wound on teeth, in other words with an undistributed winding.

The teeth of the stator may include pole shoes. Alternatively, the stator teeth are devoid of pole shoes.

The stator may include an outer casing surrounding the yoke.

The teeth of the stator can be made with a stack of magnetic sheets, each covered with an insulating varnish, in order to limit losses by induced currents.

Manufacturing process

The subject of the invention is also, independently or in combination with the foregoing, a method for manufacturing a rotor as defined above. The process can include the following steps:

(a) Provide a rotor shaft comprising at least one groove, or even two grooves, and a rotor mass comprising at least one tongue, or even two tongues,

(b) Mount the rotor mass on the rotor shaft, by inserting the tongue (s) into the corresponding groove (s), the tongue (s) being planed by the shaft when inserting the rotor mass onto the shaft. tree.

During assembly step (b), the rotor mass can be moved along the axis of rotation X relative to the shaft. The rotor mass can be held stationary, and the shaft can be threaded into the rotor mass, or alternatively the shaft can be kept stationary, and the rotor mass can be threaded onto the shaft. Thanks to the invention, the force necessary for insertion is reduced, in particular compared to a rotor which would be assembled with a clamping system. In addition, centering is easier, as is the angular alignment of the rotor poles. The insertion is facilitated, as well as the assembly process. The number of operations necessary for the implementation of the method can be reduced, as well as the need for auxiliary tools.

Planing can take place on a side edge of each tongue, or even on both side edges of each tongue. Chips from planing can be discharged at the end of the shaft, especially on the side opposite to the insertion of the rotor mass on the shaft.

Brief description of the drawings

The invention may be better understood from reading the detailed description which follows, of non-limiting examples of implementation thereof, and by examining the appended drawing, in which:

Figure 1 is a cross-sectional view, schematic and partial, of a rotor made in accordance with the invention.

Figure 2 is a detailed perspective view of the rotor of Figure 1.

FIG. 3 is a schematic and partial view of the assembly of the rotor of FIG.

1.

Figure 4 illustrates the possible positions for a 4 pole rotor.

Figure 5 illustrates the possible positions for a 6 pole rotor.

detailed description

There is illustrated in Figures 1 and 2 an inner rotor 1 of a rotating electrical machine, also comprising an outer stator not shown. The stator generates a rotating magnetic field to drive the rotating rotor 1, as part of a synchronous motor, and in the case of an alternator, the rotation of the rotor induces an electromotive force in the stator windings.

The rotor 1 shown in FIG. 1 comprises a rotor magnetic 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 sheets stacked along the X axis, the sheets being for example identical and superimposed exactly. They can be held together by clipping, rivets, tie rods, welds or any other technique. The sheets Magnets are preferably magnetic steel. All grades of magnetic steel can be used.

The rotor mass 3 has a central opening for mounting on a shaft 5. The shaft can, in the example considered, be made of a non-magnetic material, for example non-magnetic stainless steel or aluminum, or on the contrary be magnetic.

According to the invention, the rotor 1 comprises, to allow the transmission of torque between the rotor mass 3 and the shaft 5, two grooves 12 formed in the shaft 5 and two tongues 14 formed on the rotor mass 3, each tongue 14 cooperating with a groove 12.

The tongue 14 undergoes planing during the insertion of the rotor mass 3 on the shaft 5. The planing of the tongue 14 allows the existence of a pre-stress in the torque transmission means, which promotes the strength of the connection between the shaft and the rotor mass.

We will now describe in more detail the shape of a tongue 14. The tongue 14 is symmetrical. In cross section, the tongue 14 has two side edges 16 each intended to come into contact with the groove 12, in particular the sides 15 of the groove. In cross section, the tongue finally has a third circumferential edge 17 which can, before insertion of the shaft into the rotor mass, extend substantially circumferentially. This third circumferential edge 17 is not intended to be in contact with the groove.

Furthermore, the two tongues 14 and the two grooves 12 are respectively symmetrical to each other with respect to a plane of symmetry P containing the axis of the machine. It is thus possible to have torque transmission in both directions.

The planing of the tongues takes place in a plane perpendicular to the axis of rotation X of the rotor, in a circumferential direction, as shown in Figure 3.

Each tongue 14 has at its base two lateral ribs 18 on either side, which extend longitudinally, and which facilitate easy planing of the tongue. They also make it possible to avoid any possible contact between the rotor mass and the shaft, in particular one or more ridges 19 of the shaft at the level of the groove.

In the example illustrated in Figures 1 to 3, the rib has a substantially flat bottom or extending circumferentially. The rotor mass is formed by a stack of magnetic sheets all substantially identical. The stack of sheets of the rotor mass may include sheets arranged in one direction and sheets turned in the other direction, as illustrated in Figure 3, which illustrates the sheet of Figure 1 turned around an axis perpendicular to the plan

P.

Certain sheets can also be angularly offset around the axis of rotation relative to another sheet. Thus, with a single form of sheet it is possible to obtain several different angular positions.

In the embodiment of Figure 4, the rotor has 4 poles and two cyclic patterns. We can therefore have 4 different positions with one and the same sheet metal shape. Two grooves and a tongue allow these four positions to be achieved, by inserting the tongue into one or the other groove, and turning the sheet around the direct axis d.

In another exemplary embodiment illustrated in FIG. 5, the rotor has 6 poles and three cyclic patterns. The torque transmission means comprise three grooves and a tongue. We can therefore have 6 different positions with one and the same sheet metal shape. Three grooves and a tongue allow these six positions to be achieved, with insertion of the tongue in a different groove and turning around the direct axis d. In this example, there are then six rotor sections.

In this configuration, there is a groove which, in a first given cross section of the rotor, does not cooperate with the tongue, and which in a second cross section of the rotor remote from the first cross section, cooperates with the tongue. Thus, the tongue cooperates with a groove and a groove remains devoid of a tongue, in a given cross section.

The first and second cross sections belong to sections of the rotor which are angularly offset from adjacent pieces, by approximately 120 ° in the example described.

The grooves of a rotor can all have the same width or angular extent.

In the example described, the grooves are 4 mm wide, for a 43 mm diameter shaft.

In this example, the axis d can be defined generally, even in the absence of a magnet, as the axis of polar symmetry, or the axis of symmetry of a cyclic pattern. None of the grooves is symmetrical with respect to an axis d.

The twist pitch can be chosen between 1 ° and 5 °, for example between 2 ° and 3.4 °, in particular between 2.1 ° and 3 °.

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

Of course, the invention is not limited to the embodiments which have just been described.

Claims

1. Rotor (1) of an electric machine, rotating around an axis of rotation (X), the rotor comprising:

- a shaft (5) arranged on the axis of rotation (X),

- a rotor mass (3) extending along the axis of rotation (X) and arranged around the shaft, the rotor comprising at least one groove (12) formed in the shaft (5) and at least one tongue (14) formed on the rotor mass (3), the tongue cooperating with the groove for the transmission of torque between the rotor mass and the shaft, the tongue or tongues (14) undergoing planing during the insertion of the mass rotor (3) on the shaft (5).

2. Rotor according to the preceding claim, the shaft (5) being made of a material with a hardness greater than 400 HV, better still greater than 500 HV, or even greater than 600 HV, being for example a hard steel.

3. Rotor according to one of the preceding claims, the rotor mass (3) being made of a material with a hardness of less than 300 HV, better still less than 250 HV, or even less than 220 HV.

4. Rotor according to any one of the preceding claims, the groove (12) having a sharp entry edge.

5. Rotor according to any one of the preceding claims, the tongue (14) comprising at its base at least one lateral rib (18), or even two lateral ribs on either side.

6. A rotor according to any one of the preceding claims, the rotor comprising at least two grooves (12) and two tongues (14), each tongue cooperating with a groove.

7. Rotor according to any one of the preceding claims, a sheet comprising a single tongue (14) cooperating with a single groove (12) of the shaft, the rotor mass comprising sheets arranged in one direction and sheets returned in the same direction. 'other way.

8. Rotor according to any one of the preceding claims, the rotor mass (3) being formed of a stack of sheets, in particular of all substantially identical sheets, namely at least identical on the side of the shaft.

9. Rotor according to the preceding claim, at least one sheet, better all the sheets, being such that the stack of sheets includes at least one sheet offset angularly around the axis of rotation relative to another sheet, the sheets being offset by a given angle with respect to each other.

10. A rotating electrical machine comprising a rotor (1) according to any one of the preceding claims and a stator (2).

11. Machine according to the preceding claim, the stator (2) comprising electrical conductors (22), at least part of the electrical conductors (22), or even a majority of the electrical conductors, being in the form of a U or I pin. 12. A method of manufacturing a rotor (1) according to any one of claims 1 to 9, comprising the following steps:

(a) Provide a rotor shaft (5) comprising at least one groove (12), or even two grooves, and a rotor mass (3) comprising at least one tongue (14), or even two tongues

(14), (b) Mount the rotor mass (3) on the rotor shaft (5), by inserting the tab (s)

(14) in the corresponding groove (s) (12), the tongue (s) (14) being planed by the shaft during the insertion of the rotor mass (3) on the shaft (5).

13. Method according to the preceding claim, the planing taking place on a side edge of each tongue (14), or even on the two side edges of each tongue.