EP4038723A1

EP4038723A1 - Rotor for a rotating electrical machine

Info

Publication number: EP4038723A1
Application number: EP20796865.2A
Authority: EP
Inventors: Samuel KOECHLIN
Original assignee: Nidec PSA Emotors SAS
Current assignee: Nidec PSA Emotors SAS
Priority date: 2019-10-01
Filing date: 2020-09-28
Publication date: 2022-08-10
Also published as: WO2021064315A1; FR3101491B1; FR3101491A1

Abstract

Disclosed is a rotor (1) for an electrical machine, rotating about an axis of rotation (X), the rotor comprising: - a shaft (5) arranged on the axis of rotation (X), - a rotor body (3) extending along the axis of rotation (X) and arranged around the shaft, the rotor comprising means (10) for transmitting torque between the rotor body and the shaft, the torque transmission means comprising at least one groove (12) and at least two tabs (14), each tab cooperating with the groove, the tabs (14) undergoing plastic deformation when the rotor body (3) is inserted onto the shaft (5).

Description

Title: ROTATING ELECTRIC MACHINE ROTOR

The present invention claims priority of French application 1910859 filed on ¹ October 2019, the content (text, drawings and claims) is incorporated herein 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 2,549,624, this connection comprises a radial deformation of the teeth.

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 means for transmitting torque between the rotor mass and the shaft, the torque transmission means comprising at least one groove, in particular at least two grooves, and at least two tongues, each tongue cooperating with the groove or grooves, the tongues undergoing a plastic deformation 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 tongues and the groove or grooves makes it possible to make the shaft and the rotor mass integral in rotation. The plastic deformation of the tabs allows the existence of a preload in the torque transmission means, which promotes the strength 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-stressing on the rotor mass.

The implementation of the invention avoids the need for very precise sizing and high precision machining, thanks to a significant deformation of the tongues beyond the elastic limit. The lack of clearance between the rotor mass and the shaft nevertheless allows the necessary torque reversals. The cost is therefore reduced. Judicious sizing ensures torque transmission while limiting the assembly effort.

Disclosure of the invention In one embodiment, each tongue can cooperate with a groove. As a variant, two or more tongues can cooperate with the same groove. The torque transmission means may include several grooves and several tongues, in particular an even 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 groove or grooves have two lateral sides, each tongue resting on a side of the groove.

The tongue can be formed on the rotor mass, and the groove in the shaft. This configuration is particularly advantageous when the rotor mass can be deformed more easily than the shaft, since the tongue undergoes plastic deformation. This is the case, for example, when the rotor mass is formed from a stack of sheets. Apart from the groove (s), the shaft is of circular cross section. The tongue is preferably formed in a central bore of the rotor mass intended to receive the rotor shaft. The deformation of the tongue (s) can be promoted by the lamination of the rotor mass, each sheet of the rotor mass being able to deform independently of its neighbors.

Alternatively, it could be otherwise and the groove could be formed on the rotor mass, and the tongue on the shaft.

One of the tongue and groove may be asymmetric with respect to a plane containing the axis of rotation.

In an alternative embodiment, the tongue is asymmetrical. Thanks to this asymmetry, the tongue is deformed when it is inserted into the groove. In cross section, the tongue may have a first lateral edge intended to come into contact with the groove. In cross section, the tongue may have a second lateral edge which is not intended to be in contact with the groove. This second lateral edge can be substantially rectilinear, or even entirely rectilinear. It 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 include a third circumferential edge which may, before insertion of the shaft into the rotor mass, extend substantially circumferentially, then, after insertion of the shaft into the rotor mass and plastic deformation of the tongue , extend with a non-zero angle with respect to a plane normal to a radial axis of the rotor. 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 an entry chamfer. The chamfer extends longitudinally. This chamfer helps to promote the entry of the tongue when inserting the rotor mass on the shaft.

The plastic deformation of the tongue can take place in a plane perpendicular to the axis of rotation X of the rotor. The tongue deforms in a circumferential direction. Essentially, the tongue does not deform radially or axially.

The tab or tabs are deformed in the plane of the sheets so as to exert a prestress in the orthoradial direction. This deformation must be large enough to compensate for all the geometric defects in the assembly. It generates plasticization at the foot of the tongue.

The tongue may have at its base at least one lateral rib, or even two lateral ribs on either side. The rib (s) extend longitudinally. The rib or ribs allow easy deformation 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 edges of the shaft at the level of the groove.

By "base of the tongue" is meant the part of the tongue which does not fit into the groove with which it cooperates.

These lateral ribs make it possible to limit the mechanical stresses in the region of the base of the tongue. They can also make it possible to circulate a cooling fluid which can then flow along the shaft of the rotor. The lateral ribs are preferably of rounded shape in cross section, for example of circular or elliptical contour. As a variant, the lateral rib (s) may be of square or rectangular outline, or of any other polygonal shape. The lateral ribs may have an outline comprising one or more curved portions, in particular circular, and / or one or more rectilinear portions. The circular portions of the outline may have a diameter of between 2 and 7 mm, better still between 4 and 5 mm, for example of the order of 4.6 mm. The rounded side ribs have the advantage of being easy to make. In a particular embodiment, the lateral rib may be delimited by a circular portion arranged between two rectilinear portions. The value of the angle between the two rectilinear portions may be between 10 and 50 °, better still between 15 and 40 °, better still between 20 and 30 °, for example of the order of 27 °.

The lateral rib may be in contact with the circumference of the shaft at two points, for example at the level of the top of the side of the groove and at a point of the shaft outside the groove. The distance between the axis of rotation of the rotor and the point of contact between the shaft and the lateral rib outside the groove can be between 15 and 30 mm, better still between 20 and 25 mm, for example of the order of 21.8 mm. This distance is equal to the bore radius of the sheet.

The term “opening width of a lateral rib” is understood to mean the circumference of the rotor shaft between the two points of contact of the lateral rib with the rotor shaft. The opening width of the lateral rib may be between 1 and 15 mm, better still between 2 and 10 mm, for example of the order of 5.5 mm.

The torque transmission means may include 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. Preferably, during the insertion of the rotor mass on the shaft, the tabs deform in a plane perpendicular to the axis of rotation X of the rotor as they approach each other. In one embodiment, they may not deviate from each other. The purpose of this bringing together between the two tongues is to improve the mechanical strength of the sheet on the rotor shaft. Before inserting the rotor mass onto the rotor shaft, each tongue protrudes from the side of the groove and covers the rotor shaft over an interference width between 0.05 and 0.5 mm, better still between 0.1 and 0.4 mm, better still between 0.2 and 0.3 mm, for example of the order of 0.23 mm.

In one embodiment, a recess may be present between the two tongues cooperating with the same groove. A median plane of the recess may be a plane containing the X axis of rotation and dividing the recess into two equal parts. There may be a plane of symmetry for the recess. The two tongues can be symmetrical to one another with respect to the median plane of the recess. The recess has a bottom which is disposed between the bases of the two tongues. The bottom of the recess preferably has a portion of rounded shape, for example circular or elliptical. As a variant, the bottom of the recess may present at the base of the two tongues a portion which may be square, rectangular, or of any other polygonal shape. In an alternative embodiment, the recess is delimited by a curved portion disposed between two rectilinear portions. When it is circular, the bottom portion of the recess may have a diameter of between 0.5 and 8 mm, better still between 1 and 4 mm, for example of the order of 2 mm. The presence of a recess of such a shape and size makes it possible to avoid the initiators of fracture from a mechanical strength point of view. This recess also makes it possible to limit the risk of contact between the two tongues when they come closer at the time of insertion on the shaft. Finally, such a recess is large enough so that the cutting punch is not too thin.

The distance between the axis of rotation and the center of the curvature of the circular portion of the bottom of the recess between two tongues cooperating with the same groove may be between 15 and 30 mm, better still between 20 and 25 mm, for example. of the order of 23.8 mm.

The distance between the point of the lateral rib furthest from the axis X of rotation and the point of the recess furthest from the axis X of rotation is called "width at the foot of a tongue". The width at the foot of each tongue is for example between 1 and 15 mm, better still between 2 and 10 mm, better still between 4 and 8 mm, for example of the order of 6.9 mm. Tongues having such a width at the foot have the advantage of not deforming too markedly when inserting the sheet onto the shaft. Such tongues thus ensure good retention of the sheets during the rotation of the rotor.

Each tab has two side edges. The two side edges are connected by a circumferential edge forming the end of the tongue. The width of the end of the tongue is between 0.5 and 10 mm, better still between 1 and 5 mm, for example of the order of 1.8 mm. The side edge (s) may be rectilinear. As a variant, the lateral edge (s) may comprise at least one rectilinear portion and one curved portion. For example, the lateral edge (s) may comprise three curved portions and two rectilinear portions. Preferably, the two lateral edges of each tongue comprise at least one curved portion and at least one rectilinear portion. As a variant, the two side edges of each tab are rectilinear. As a further variant, one of the side edges is rectilinear and the other side edge has at least one curved portion and at least one portion. straight. As a further variant, one of the lateral edges comprises a curved portion and a rectilinear portion and the other lateral edge comprises three curved portions and two rectilinear portions. Preferably, the rectilinear portions of the two lateral edges of each tongue are not parallel. As a variant, the rectilinear portions of the side edges are parallel.

The median plane of a tongue is considered to be the plane containing the X axis of rotation passing through the middle of the end of the tongue. Preferably, each tab is asymmetrical with respect to its median plane. The rectilinear portions can form an angle with the median plane of the tongue by a value of between 1 and 40 °, better between 5 and 30 °, better between 10 and 20 °, for example of the order of 12 or 15 ° . Preferably, the inclination of the rectilinear portions of the side edges of a tongue is not the same for the two side edges.

The width of the tongue may not be constant. For example, the tongue may be thinner at its end than at its base. The width of the tongue base can vary between the circumference of the shaft and the foot of the tongue. For example, the width of the base of the tongue may increase by the circumference of the shaft at the foot of the tongue. Such a form of tongue makes it possible to better distribute the bending stresses. As a variant, the tongue may be wider at its end than at its base. In an alternative embodiment, the tongue may be of constant width.

The distance between the two lateral edges of the two tongues in contact with the sides of the groove can be between 1 and 30 mm, better between 2 and 20 mm, better between 5 and 10 mm, for example of the order of 6 , 4 or 7.2 mm. Preferably, this spacing is not constant over the entire length of the tongues.

When at least one of the lateral edges of one of the tabs comprises at least one curved portion and at least one rectilinear portion, the latter may in particular include a convex portion in its part closest to the X axis of rotation. Such a convex shape makes it possible to ensure that the contact between the lateral flank of the tongue and the groove is always made in the same zone.

When two tongues cooperate with the same groove, the width of each tongue at the level of the circumference of the shaft may be between 0.5 and 10 mm, better still between 1 and 5 mm, even better between 2 and 3 mm, for example of the order of 2.93 mm. The width of the tongue at the level of the deformation thereof may be between 1 and 10 mm, better still between 2 and 5 mm, more preferably between 3 and 4 mm, for example of the order of 3.2 mm. Such a width makes it possible to ensure a good holding force of the tongue against the tree.

The two tongues cooperating with the same groove can be spaced apart by a distance of between 0.5 and 10 mm, better still between 1 and 5 mm, better still between 2 and 4 mm, for example of the order of 2.6 mm . The spacing distance of the two tabs corresponds to the width of the recess.

The distance between the median plane of the recess and the side edge closest to the recess of one of the two tabs measured at the level of the end of the tab is between 0.2 and 5 mm, better between 0.5 and 2.5 mm, better still between 1 and 2 mm, for example of the order of 1.3 mm.

The torque transmission means may include a single groove and two tongues cooperating with this groove. As a variant, the torque transmission means may include two grooves arranged at 180 ° to each other and four tongues, each groove cooperating with two tongues. As a variant, the torque transmission means may comprise three grooves arranged at 120 ° to each other and six tongues, each groove cooperating with two tongues. As a further variant, the torque transmission means may comprise four grooves arranged at 90 ° to each other and eight tongues, each groove cooperating with two tongues.

As a variant, the torque transmission means may comprise at least two grooves and two tongues, each tongue cooperating with a groove. The torque transmission means 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. In one embodiment, the torque transmission means comprise two grooves and two tongues, each tongue cooperating with a groove. As a variant, the torque transmission means comprise four grooves and four tongues, each tongue cooperating with a groove. As a further variant, the torque transmission means comprise three grooves and three tongues, each tongue cooperating with a groove. In one embodiment, the torque transmission means may include a groove which, in a first given transverse section of the rotor, does not cooperate with a tongue. A tongue may cooperate with said groove in a second cross section of the rotor remote from the first cross section. The torque transmission means 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, when braking. The torque transmission means can for this purpose comprise contact zones between the groove or grooves and the tongues which are opposite 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.

The rotor mass can be 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.

The stack of sheets of the rotor mass may include sheets arranged in one direction and sheets turned in the other direction. The sheets can be turned over in bundles, the stack of sheets of the rotor mass comprising an alternation of packs of sheets arranged in one direction and packs of sheets turned upside down in the other direction. A more homogeneous distribution of the stresses in the rotor is thus obtained. Performances of the machine are improved, particularly 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 two tongues 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 two tongues allow these six positions to be achieved.

The rotor may include permanent magnets, with in particular 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 in a material from the following list, which is not exhaustive: steel, stainless steel, titanium or any other non-magnetic material

The rotor mass can in one embodiment be arranged 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 in the tool, in complete packages or under- 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 with respect to adjacent pieces.

The torque transmission means 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 rotor mass with respect to the shaft, as a function of the sections and of the cooperation or not of one or more tongues with the groove of different angular extent or width, eg higher.

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, which may be in the shape of a U-shaped or I-shaped 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, to position 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. By "fully closed notch" is meant 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 bridges of material closing the notches. The bridges of material can 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 yoke or in one piece with the teeth. The notches are then not open radially outwards. The stator mass may have no 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 be without magnetic wedges attached 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. By "distributed" is meant 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. Electrical conductors at least, see a majority of electrical conductors, can be in the shape of pins, U or I. The pin can be U-shaped ("U-pin" in English) or straight, being in form of I ("I-pin" in English).

In the invention, each electrical conductor can comprise one or more strands (“wire” or “strand” in English). By “strand” is meant the most basic unit for electrical conduction. A strand can be of round cross section, then we can speak of 'thread', or flat. The flat strands can be shaped into pins, for example U or 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 corrugated. 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 viewed perpendicular to the axis of rotation of the machine.

The winding can have a single winding path or several winding paths. In an "electrical conductor" flows the current of the same phase by winding. By "winding path" is meant 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 stator teeth 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 above, 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 two tongues,

(b) Mount the rotor mass on the rotor shaft, by inserting the tongues into the corresponding groove (s).

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 required 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. Insertion is made easier, as is 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.

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 view similar to FIG. 1 of an upturned sheet.

Figure 4 is a view similar to Figure 2 of an alternative embodiment.

FIG. 5 is a schematic and partial view of the assembly of the rotor of FIG.

4.

Figure 6 is a cross-sectional view, schematic and partial, of the rotor of Figure 4.

Figure 7 illustrates the possible positions for a 4 pole rotor.

Figure 8 illustrates the possible positions for a 6 pole rotor.

Figure 9 is a cross-sectional view, schematic and partial, of an alternative embodiment.

Figure 10 is a detail view of Figure 9.

Figure 11 is a perspective view of the shaft of the embodiment of Figures 9 and 10.

Figure 12 is a cross-sectional view, schematic and partial, of the shaft of Figure 11.

FIG. 13 is a detailed perspective view of an alternative embodiment.

Figure 14 is a cross-sectional view, schematic and partial, of the rotor of Figure 13.

Figure 15 is a perspective view of the rotor of Figure 13.

Figure 16 is a view similar to Figure 14.

Figure 17 is a view similar to Figure 14.

Figure 18 is a view similar to Figure 14.

Figure 19 is a detail view of Figure 14.

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 by example formed by a package of magnetic sheets stacked along the X axis, the sheets being for example identical and exactly superimposed. They can be held together by clipping, rivets, tie rods, welds or any other technique. The magnetic sheets are preferably made of 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 under consideration, 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 torque transmission means 10 between the rotor mass 3 and the shaft 5. These torque transmission means comprise two grooves 12 formed in the shaft 5 and two tongues 14 formed on the shaft. the rotor mass 3, each tongue 14 cooperating with a groove 12.

The tongue 14 undergoes a plastic deformation during the insertion of the rotor mass 3 on the shaft 5. The plastic deformation of the tongue 14 allows the existence of a prestress in the torque transmission means, which promotes strength. 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 asymmetric. In cross section, the tongue 14 has a first lateral edge

15 intended to come into contact with the groove 12, in particular the side of the groove. In cross section, the tongue has a second lateral edge 16 which is not intended to be in contact with the groove. This second lateral edge is rectilinear, extending parallel to a radial axis of the rotor. In cross section, the tongue finally comprises a third circumferential edge 17 which may, before insertion of the shaft into the rotor mass, extend substantially circumferentially, then extend, after insertion of the shaft into the rotor mass and deformation. plastic of the tongue, with a non-zero angle with respect to a plane normal to a radial axis of the rotor. 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 one another with respect to a plane of symmetry P containing G axis of the machine. It is thus possible to have torque transmission in both directions. The grooves 12 each have an inlet chamfer 13 which extends longitudinally, which makes it possible to promote the entry of the corresponding tongue when inserting the rotor mass 3 on the shaft 5.

The plastic deformation of the tabs takes place in a plane perpendicular to the axis of rotation X of the rotor, in a circumferential direction. The tongues are deformed in the plane of the sheets so as to exert a prestress in the orthoradial direction. This deformation must be large enough to compensate for all the geometric defects in the assembly. It generates plasticization at the foot of the tongue.

Each tongue 14 has at its base two lateral ribs 18 on either side, which extend longitudinally, and which facilitate easy deformation 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 and 2, the rib has a substantially flat bottom or extending circumferentially.

Alternatively, the rib 18 may be in cross section of generally rounded shape, as illustrated in Figure 4.

When inserting the rotor mass onto the shaft, a fairly significant deformation of the tongues is then obtained, which causes plasticization at the foot of the tongue 14, in a zone Z, as illustrated in Figures 5 and 6.

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 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.

In the embodiment of FIG. 7, 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 two tongues make it possible to achieve these four positions, with rotation of 180 ° in the plane and turning around the direct axis d. In another exemplary embodiment illustrated in FIG. 8, the rotor has 6 poles and three cyclic patterns. The torque transmission means comprise three grooves and two tongues, each tongue of the pack of sheets resting successively on a different groove side, when moving along the axis of rotation of the rotor. We can therefore have 6 different positions with one and the same sheet metal shape. Three grooves and two tongues make it possible to achieve these six positions, with rotation of 120 ° in the plane and turning around the direct axis d. In this example, we then have three sections of the rotor, or a multiple of three.

In this configuration, there is 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. Thus, each 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. As a variant, and as illustrated schematically in FIG. 8, they may comprise three grooves having different angular extents or widths. This configuration makes it possible to obtain a certain angular offset of the rotor mass 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.

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

A uniform twist pitch of 2.78 ° is obtained. Indeed, in this example, the angle a1 between the direct axis, which defines the middle of a pole, and the first side of the widest groove is 3.78 °. The angle a2 between the direct axis, which defines the midpoint of a pole, and the second flank of the widest groove is 9.35 °. The angle a3 between the direct axis, which defines the midpoint of a pole, and the first flank of the second groove is 119 °. Finally, the angle a4 between two consecutive tongues after assembly, that is to say after plastic deformation, is 135.90 °. 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 are symmetrical about an axis d.

Note also that in this example, the angle a4 giving the distance between the tongues is equal to the sum of the angle of the cyclic pattern plus the width of the groove plus the twist pitch.

In general, we have the gap between the tabs which is equal to or close to the sum between the angle of the cyclic pattern and the groove width.

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

In an alternative embodiment illustrated in FIGS. 9 to 12, the grooves comprise two identical grooves, and a third groove having a different angular extent or width, namely greater. This configuration makes it possible to obtain a certain angular offset of the rotor mass 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. superior.

In the example given in Figures 9 to 12, the rotor has six cyclic patterns. The d axis 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.

We will now describe with reference to Figures 13 to 19 an alternative embodiment of the invention in which the torque transmission means 10 between the rotor mass 3 and the shaft 5 comprise a single groove 12 formed in the shaft 5 and two tongues 14 formed on the rotor mass 3, the two tongues 14 cooperating with the groove 12.

As illustrated in Figure 17, before inserting the rotor mass onto the rotor shaft, each tongue protrudes from the side of the groove and covers the rotor shaft over an interference distance di of the order of 0.23 mm.

As shown in Figures 13 to 15, each tongue 12 comprises at its base a lateral rib 18. Each lateral rib 18, when observed in cross section, is delimited by a contour which comprises a circular portion 180 disposed between two rectilinear portions 181, 18G. The diameter of the circular portion 180 is of the order of 4.6 mm. Lateral rib 18 is in contact with the circumference of the shaft at the top side of the groove A1 and at a point of the shaft outside the groove A2. In the example shown, the opening length lo of the lateral rib is of the order of 5.5 mm.

As illustrated in FIG. 16, the distance Rn between the axis X of rotation of the rotor and the point A2 of contact between the shaft and the lateral rib outside the groove is of the order of 21.8 mm. The angle between the two rectilinear portions 181, 18G is of the order of 25 °.

In the embodiment illustrated in Figures 13 to 19, a recess 20 is present between the two tongues 14 cooperating with the same groove 12. The median plane of the recess Pe contains the axis X of rotation and divides the recess 20 in two equal parts. The two tongues 14 are symmetrical to one another with respect to the plane Pe. The recess 20 has a bottom which is disposed between the bases of the two tongues. The bottom of the recess is delimited by a circular portion 201 disposed between two rectilinear portions 202, 202 '. The diameter of the circular portion 201 of the bottom of the recess 20, visible in FIG. 16, is of the order of 2 mm.

The distance Re between the axis of rotation X and the center Ce of curvature of the circular part of the bottom of the recess 20 is of the order of 23.8 mm.

The foot width Lp of each tongue is measured between the point An of the lateral rib 18 furthest from the axis X of rotation and the point Ae of the recess 20 furthest from the axis X of rotation. In the example shown, the foot width Lp of each tab is of the order of 6.9 mm.

Each tongue has two side edges 140, 141. The two side edges are connected by a circumferential edge forming the end 142 of the tongue. In the example illustrated in FIG. 19, the lateral edge 140 comprises a rectilinear portion 1400 and a curved portion 1401. The rectilinear portion 1400 of the lateral edge 140 extends between the end 142 of the tongue and the curved portion 1401. The rectilinear portion 1401 of the lateral edge 140 forms with the end 142 of the tongue a substantially right angle. The other lateral edge 141 of the tongue has two rectilinear portions 1410, 140 'and three curved portions 1411 141 G 1411 ". The end 142 of the tongue is connected to the lateral edge 141 by the curved portion 1411. It is thus formed. a convex part which makes it possible to ensure that the contact between the lateral edge of the tongue and the groove is always made in the same zone. The median plane PI of the tongue 14 is the plane containing the axis X of rotation passing through the middle I of the end 142 of the tongue. Each tab is asymmetrical with respect to its median plane PL

The rectilinear portion 1400 is inclined at an angle of the order of 15 ° relative to the median plane PL The rectilinear portion 1410 is inclined at an angle of the order of 12 ° relative to the median plane Pl. illustrated example, the width of the tongue is not constant. The tongue is thinner at its end 142 than at its base.

In the example shown, the width of the tongue is thinner at its end than at its base. The width of the ends 142 is of the order of 1.8 mm and the width of the tongues at the circumference of the shaft is of the order of 2.9 mm.

The width of the tongue at the level of the deformation thereof is of the order of 3.2 mm.

The two tongues 14 are spaced apart by a distance of the order of 2.6 mm. This distance corresponds to the width of the recess 20. The distance between the median plane of the recess Pe and the side edge 140 closest to the recess measured at the level of the end of the tongue is order of 1.3 mm.

As illustrated in FIG. 18, the further one moves away from the axis of the rotor, the more the width between the edges in contact with the flanks of the groove 12 increases. Thus, the width IRI between the two edges of the two tongues measured at a distance RI from the X axis of rotation is greater than the width 1 _R2 measured at a distance R2 from the axis X of rotation when the distance RI is greater than the distance R2.

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 torque transmission means (10) between the rotor mass and the shaft, the means torque transmissions comprising at least one groove (12) and at least two tongues (14), each tongue cooperating with the groove or grooves, the tongues (14) undergoing a plastic deformation during the insertion of the rotor mass (3 ) on the shaft (5), the rotor mass (3) being formed by a stack of sheets comprising sheets arranged in one direction and sheets turned in the other direction.

2. 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 torque transmission means (10) between the rotor mass and the shaft, the means torque transmissions comprising at least two grooves (12) and at least two tongues (14), each groove cooperating with a tongue, the tongues (14) undergoing a plastic deformation during the insertion of the rotor mass (3) on the shaft (5), the tongues being asymmetrical with respect to a plane containing the axis of rotation (X), the tongues comprising in cross section a first lateral edge (15) intended to come into contact with the groove and a second lateral edge (16) which is not intended to be in contact with the groove.

3. Rotor according to the preceding claim, the tongue (14) being formed on the rotor mass (3), and the groove (12) in the shaft (5).

4. Rotor according to one of the preceding claims, one of the tongue (14) and the groove (12) being asymmetric with respect to a plane containing the axis of rotation (X).

5. Rotor according to any one of the preceding claims, the groove (12) comprising an inlet chamfer (13).

6. A rotor according to any one of the preceding claims, the plastic deformation of the tongue taking place in a plane perpendicular to the axis of rotation (X) of the rotor.

7. 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.

8. Rotor according to one of the preceding claims, the torque transmission means (10) comprising at least two grooves (12) and two tongues (14), each tongue cooperating with a groove.

9. Rotor according to the preceding claim, the two tongues (14) and the two grooves (12) being respectively symmetrical to each other with respect to a plane (P) of symmetry containing the axis of rotation (X). of the rotor.

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

11. Rotor according to the preceding claim, the stack of sheets of the rotor mass (3) comprising sheets arranged in one direction and sheets returned in the other direction.

12. Rotor according to one of the two preceding claims, at least one sheet, better still all the sheets, being such that the stack of sheets comprises at least one sheet offset angularly around the axis of rotation with respect to a other sheet.

13. A rotor according to any preceding claim, comprising permanent magnets.

14. Rotating electric machine (10) comprising a rotor (1) according to any one of the preceding claims and a stator (2).

15. 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 shape of a U or I pin. .

16. A method of manufacturing a rotor (1) according to any one of claims 1 to 13, 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 two tongues (14), (b) Fit the rotor mass (3) on the rotor shaft (5), by inserting the tongues (14) in the corresponding groove (s) (12).