Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02K—DYNAMO-ELECTRIC MACHINES
  • H02K1/00—Details of the magnetic circuit
  • H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
  • H02K1/22—Rotating parts of the magnetic circuit
  • H02K1/27—Rotor cores with permanent magnets
  • H02K1/2706—Inner rotors
  • H02K1/272—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis
  • H02K1/274—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets
  • H02K1/2753—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets the rotor consisting of magnets or groups of magnets arranged with alternating polarity
  • H02K1/276—Magnets embedded in the magnetic core, e.g. interior permanent magnets [IPM]
  • H02K1/2766—Magnets embedded in the magnetic core, e.g. interior permanent magnets [IPM] having a flux concentration effect

Definitions

• the present invention relates to rotating electrical machines, including synchronous machines, including motors, and more particularly the rotors of such machines.
• the invention is concerned with permanent magnet and flux concentration rotors.
• the flux concentration rotors comprise a rotor mass in which permanent magnets are housed, the latter being engaged in housings oriented most often radially.
• the magnetic flux of the permanent magnets must bounce at the level of the stator through the air gap and not at the level of the rotor, in particular of its shaft.
• rotors comprising a non-magnetic hub on which polar parts are inserted between which are inserted the permanent magnets, as described for example in the patent applications EP 1 152 516 and EP 1 249 919.
• the magnetic poles located on either side of the magnets, are totally separated magnetically and also constitute separate parts. Such a configuration can complicate the establishment of the magnetic poles and their maintenance on the hub.
• pole pieces are also separate pieces.
• the patent application DE 10 200 003228 relates to a rotating electronic machine rotor comprising permanent magnets arranged in housings open towards the inside of the rotor, but without the means for driving in rotation of the rotor mass are described. The same is true of the patent application EP 1 420 499. There are also solutions consisting of making one or more recesses in the rotor to limit magnetic flux losses. Applications US 2007/0252469 and WO 2009/153511 describe solutions of this type.
• the pole pieces are connected to the hub of the rotor by material bridges, in particular by two material bridges at the foot of each magnet on either side thereof, and the magnets are blocked. between the pole pieces by centrifugation.
• material bridges at the foot of the permanent magnets has a negative impact on the mass power of the machine and the wedging of the magnets between the pole pieces is not necessarily optimal.
• the presence of magnetic steel under the magnets can generate magnetic flux leaks that can be significant and deteriorate the characteristics electromagnetic machine.
• the flux losses can take place on a significant part of the height of the magnet measured radially, up to 25% for example.
• An object of the invention is to reduce or even eliminate flux leakage, especially at the foot of magnets.
• the present invention aims to meet this need and to overcome all or part of the disadvantages mentioned above.
• the object of the invention is, according to one of its aspects, a rotating electric machine rotor with flux concentration, comprising:
• a rotor mass disposed on the shaft, having a central opening for mounting it on the shaft, and comprising:
• the stack defining the housings in which the permanent magnets are arranged.
• Such a configuration makes it possible to minimize or even eliminate magnetic leaks at the foot of the magnets, which are suitable for stacking, thanks to the absence of material magnetic between the magnets and the shaft. This absence is not detrimental to the cohesion of the rotor mass, thanks to the fact that at least one of the layers is in one piece.
• a magnetic sheet layer, or even all magnetic sheet layers, can be in one piece.
• the rotor mass is advantageously formed entirely by an assembly of rotor plates each monobloc or by a winding of a sector band.
• the rotor is devoid of reported pole pieces, and the construction of the rotor is simplified.
• the stack of magnetic sheet layers may comprise a stack of magnetic sheets, each in one piece, each sheet forming a layer of the stack.
• a magnetic sheet layer may be formed of several independent sectors, arranged alternately with the magnets and held together by an outer ring.
• the stack of magnetic sheet layers may comprise one or more magnetic sheet (s) wound (s) on it (s) itself, each sheet may form several layers of the stack according to the number of turns on which it is rolled up on itself.
• a sheet may comprise a succession of sectors connected by material bridges.
• Material bridges can form the bottom of a housing of a permanent magnet, on the side of the gap.
• a sheet may comprise a number of sectors equal to the number of poles of the rotor.
• a sheet may comprise a number of sectors greater than the number of rotor poles, for example a multiple of the number of rotor poles, two sectors of one and the same plate that can be superimposed on one another when the sheet is wound to form the rotor mass.
• each rotor plate is cut from a sheet of magnetic steel, for example steel 0.1 to 1.5 mm thick.
• the sheets can be coated with an electrical insulating varnish on their opposite faces before assembly within the stack. The insulation can still be obtained by a heat treatment of the sheets.
• the sheet (s) are open towards the rotor shaft.
• Each of the sheets can define at least two housings for permanent magnets, in particular at least three, better a housing number equal to the number of rotor poles, or more.
• At least one housing is of oblong shape, preferably elongated in a radial direction.
• Preferably, all the housings are oblong, elongate in a radial direction.
• the housings may have an axis of greater size which coincides with a radius of the rotor, or not. The larger axis may be parallel to a radius.
• Such dwellings include dwellings for which the greatest radial dimension of the dwelling is greater than the greatest circumferential dimension of the dwelling, measured between two points at the same distance from the center, along a segment passing through these points and perpendicular to a bisecting ray.
• the distribution of the housings is advantageously regular and symmetrical, facilitating the cutting of the rotor sheet and the mechanical stability after cutting when the rotor mass consists of a superposition of rotor plates.
• the number of housings and magnets depends on the polarity of the rotor.
• the rotor mass may comprise any number of housing pairs, for example 6 or 8 slots.
• the dwellings may have a longitudinal dimension, in particular radial, greater than or equal to that of the permanent magnets received inside these dwellings. This may allow wider manufacturing tolerances of the rotor mass and magnets and may allow, if necessary, jamming of the magnets in the housings by centrifugation.
• Magnets can be buried in the rotor mass. In other words, the magnets are covered by the layers of magnetic sheets at the gap. The surface of the rotor at the air gap can be entirely defined by the edge of the magnetic sheet layers and not by the magnets. The housing does not open then radially outward.
• the shaft may be made of a non-magnetic material, for example non-magnetic stainless steel, aluminum or plastic, which advantageously makes it possible to further reduce magnetic leakage and to improve the electromagnetic performance of the rotor.
• the shaft may comprise a nonmagnetic sleeve in contact with the rotor mass, the sleeve being mounted on an axis, magnetic or not, preferably non-magnetic.
• the shaft may be without an insert. It can be completely non-magnetic.
• the rotor may be devoid of insert between the rotor mass and the shaft.
• the shaft may comprise torque transmission means for driving in rotation of the rotor mass, for example splines at its periphery, or flats in contact with corresponding plates formed on the rotor mass.
• the embodiment of the grooves may advantageously require only a little precision, while providing a satisfactory result in the mounting and driving of the rotor mass.
• the shaft may have grooves at its periphery, which can penetrate into correspondingly shaped notches in the rotor mass.
• the shaft may have notches for receiving correspondingly shaped grooves formed in the rotor mass.
• the profile of a groove may be in cross-sectionally developing section, which may facilitate the centering of the shaft relative to the rotor mass, and excellent torque transmission.
• the profile of the grooves may be different and the centering to be otherwise.
• the grooves may for example be made by cold deformation, in particular by rolling by means of rollers, or by cutting, or broaching, or by another method.
• the grooves may extend over a portion only of the length of the shaft, and in particular over all or part of the length of the rotor.
• the flutes may extend over several portions of the length of the shaft, separated by one or more portions without flutes, for example two fluted portions each located at one end of the rotor mass.
• the length of the grooved zone (s) may be chosen so as to be sufficient to allow the transmission of torque, while at the same time making it possible to limit the manufacturing difficulties of these splines.
• the number of splines may be equal to the number of poles of the rotor, or be a multiple of the number of poles of the rotor, for example double.
• the grooves extend radially beyond permanent magnets.
• the permanent magnets are farther from the axis of rotation than the top of the flutes.
• the grooves thus cooperate with a sheet portion that is not radially at the same level as one or more magnets.
• the grooves protrude in the stack between two consecutive permanent magnets.
• the flutes extend radially at least partially between the permanent magnets.
• the permanent magnets may each have, in cross section, a shape not entirely rectangular and not completely trapezoidal.
• the magnets may for example have a shape that is both partially rectangular and partially trapezoidal.
• a magnet may comprise in cross section two edges which are parallel to one another on a first portion of the cross section of the magnet, and two edges converging towards each other towards the axis of rotation on a second portion of the cross section of the magnet.
• This second portion may be closer to the axis of rotation than the first portion.
• the permanent magnets thus have a tapered shape at their end closest to the axis of rotation, which makes it easier to keep close to the shaft a width of the sheet between the magnets sufficient, especially for the strength of the rotor , while benefiting from magnets with a large radial dimension and therefore a rotor mass having a large radial extent, with a shaft having a relatively small diameter.
• the rotor mass and the magnets can be configured to allow the placing of the magnets in the stack of magnetic sheet layers only in one direction, so as to act as a polarizer during assembly and avoid fixing a magnet with a reversed polarity relative to that which is appropriate. Keying can be achieved in a variety of ways.
• the sheets may be slightly offset relative to each other in the stack, a magnet having a corresponding dissymmetry, so as to allow the insertion of a magnet in the stack only in one direction.
• the rotor mass may for example comprise a reported polarizer fixed to the sheet stack before the establishment of magnets.
• the polarizer is for example integrated in a magnetic envelope of the permanent magnets, present on the latter before their introduction into the stack.
• a permanent magnet may be asymmetrical with respect to a median plane and be for example asymmetrical with respect to a radius of the rotor cutting it in the middle, once in place thereon.
• a dwelling may be asymmetrical with respect to a median plane.
• Such a plane can extend both longitudinally and radially.
• each of the two edges of a permanent magnet which converge towards each other can respectively form with a radius of the cutting rotor the magnet corresponding in its middle a first angle and a second angle, the first and second angles being different.
• Two consecutive magnets may be placed symmetrically to each other with respect to a plane passing between them, this plane extending both radially and longitudinally, that is to say along the axis of rotation of the rotor, for example with respect to a radius of the rotor passing between them.
• two consecutive magnets are placed inverted in the stack.
• two consecutive housings may also be symmetrical to one another with respect to a plane containing a radius of the rotor and passing between them.
• At least one housing may have a first portion which is delimited laterally by opposite edges parallel to each other. At least one housing may have a second portion which is delimited laterally by opposite edges converging towards each other in the direction of the axis of rotation.
• a convergent edge of a housing and a consecutive convergent edge of the consecutive housing can form with a radius of the rotor passing in their middle two equal angles.
• the portion of sheet defined by the two consecutive housings then has edges forming with respective radii of the rotor cutting the sheet portion in the middle two equal angles.
• the two consecutive edges may in one embodiment be parallel. All two consecutive edges of the sheets can be parallel two by two.
• the two edges of a portion of sheet metal on two can be parallel to each other when moving around the axis of rotation of the rotor, while the edges of the other sheet portions converge toward the axis of rotation.
• At least one housing may have a third portion delimited by convergent opposing edges that can cooperate with the shaft to allow the drive of the rotor mass.
• the opposite edges of the third portion may or may not be rectilinear. They may for example be curved, of shape corresponding at least partially to the shape of the flutes.
• At least one permanent magnet may comprise a mark making it possible to differentiate one from the other its two longitudinal end faces. It may be for example a colored sign. This mark can help the operator to correctly orient the magnet when inserted into the corresponding slot.
• All permanent magnets may include a mark for differentiating the two longitudinal end faces of a magnet from one another. These marks can allow easy and quick visual inspection of the correct placement of the magnets in their housing after assembly. For example, when we observe the rotor along its axis of rotation by one of its ends, we can see the presence of the mark on all magnets on one side, and no mark on the other side. As a variant, especially in the case where two consecutive housings are different and symmetrical with respect to each other, it is possible to note the presence of a mark on one magnet out of two, and the same is true when observe the rotor on the other side.
• the rotor can be cantilevered or not.
• the rotor mass may comprise one or more holes to lighten the rotor, to allow its balancing or for the assembly of the rotor plates constituting it. Holes may allow the passage of tie rods now integral with the sheets.
• the sheet layers can be snapped onto each other.
• the housings can be filled at least partially with a non-magnetic synthetic material. This material can lock in place the magnets in the housing and / or increase the cohesion of the sheet package.
• the rotor mass may comprise, where appropriate, one or more reliefs contributing to the proper positioning of the magnets, especially in the radial direction.
• the rotor mass may have an outer contour which is circular or multilobed, a multi-lobed shape may be useful for example to reduce torque ripples or harmonics of current or voltage.
• the rotor can receive an outer ring, which surrounds the package of sheets. This can reduce the width of the material bridge connecting two consecutive sectors.
• a rotary electric machine rotor with flux concentration comprising:
• a rotor mass disposed on the shaft, defining a central opening for mounting it on the shaft, and comprising:
• the permanent magnets having in cross section two radial edges which are convergent towards each other in the direction of the axis of rotation, on a portion of the cross section of the magnet.
• the permanent magnets thus have a tapered shape at their end closest to the axis of rotation, which makes it possible to maintain a sufficient width of the sheet between the magnets, in particular for the strength of the rotor, while benefiting from magnets having a relatively large radial dimension.
• Each of the two radial edges of a permanent magnet that are convergent towards one another can form respectively with a radius of the cutting rotor the corresponding magnet in its middle a first angle and a second angle, the first and second angles being different.
• a permanent magnet is asymmetrical with respect to a radius of the rotor cutting it in the middle and with respect to a median plane.
• a housing is asymmetrical with respect to a radius of the rotor cutting it in the middle and relative to a median plane.
• the housing can open radially to the central opening.
• the rotor thus defined may also include one or more of the characteristics mentioned above.
• the invention also relates to a rotating electrical machine, such as a synchronous motor or a synchronous generator, comprising one of the rotors as defined above.
• This machine may comprise a stator with concentrated or distributed winding.
• FIG. 1 is a diagrammatic and partial perspective view of an exemplary rotor made in accordance with the invention
• FIG. 2 is a schematic and partial perspective view of the rotor shaft of FIG. 1,
• FIG. 3 is a cross-section, diagrammatically and partially, of the rotor of FIG. 1;
• FIG. 4 represents, in isolation and from the front, a magnetic sheet,
• FIG. 5 represents a detail of FIG. 4,
• FIG. 6 represents a detail of embodiment of FIG. 3,
• FIG. 7 is a view similar to FIG. 6 illustrating an alternative embodiment
• FIGS. 7a and 7b are views similar to FIG. 7 of alternative embodiments.
• 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 stack of magnetic sheets 4 stacked along the X axis, the sheets being for example identical and superimposed exactly. They can be held in each other by clipping, rivets, welds or any other technique.
• the rotor mass may comprise at least one magnetic sheet wound on itself.
• a sheet comprises a succession of sectors 4a connected by material bridges 4b, the material bridges can form the bottom of a housing of a permanent magnet.
• the magnetic sheets are preferably magnetic steel. All grades of magnetic steel can be used.
• the rotor mass 3 is mounted on a shaft 2 which, in the example considered, is made of a non-magnetic material, for example non-magnetic stainless steel or aluminum.
• the material may for example be type 304 nonmagnetic stainless steel.
• the rotor mass 3 comprises a central opening 5 for mounting on the shaft 2.
• the fixing of the rotor mass 3 on the shaft 2 can be done by means of an axial locking system, for example with one side a stop 2b material and on the other side a serrated stop washer 6.
• the assembly can be performed cold or hot.
• the transmission of the torque is obtained by grooves 2a disposed at the periphery of the shaft 2.
• the profile of a groove may be in cross section involute.
• the flutes may extend over one or more portions only of the length of the shaft, as illustrated in Figure 2, where the flutes extend over two portions of the length of the shaft separated by a portion without flutes, each located at one end of the rotor mass.
• the clearances 2c obtained on both sides of the fluted portions may allow to receive any chips that would be formed during the establishment of the rotor mass 3 on the shaft 2, and not to disturb the good axial positioning of the assembly.
• the stiffness of the rotor mass is preferably chosen so that the latter can deform when mounting on the spline shaft.
• the rotor 1 comprises a plurality of permanent magnets 7 arranged in corresponding housings 8 of the rotor magnetic mass 3, so that two consecutive magnets 7 have the same polarities on their facing faces.
• the magnets may for example be made of ferrite or alternatively rare earths, for example neodymium or other type.
• the rotor 1 is disposed inside a not shown stator, which comprises for example a concentrated or distributed winding.
• This stator makes it possible to generate a rotating magnetic field driving the rotor in rotation, in the context of a synchronous motor, and in the case of an alternator, the rotation of the rotor induces an electromotive force in the stator windings.
• the housings 8 do not open on the outside of the rotor sheet.
• the housings 8 may in particular be separated from the periphery of the rotor sheet by the material bridge 4b formed in the sheet, of a thickness e preferably between 0.1 and 3 mm.
• the magnets can be configured to provide a keying when they are placed in the rotor mass.
• they may in particular be asymmetrical with respect to a median plane intersecting them in their middle. They may for example each have, in cross section, a shape not entirely rectangular and not completely trapezoidal.
• the permanent magnets may be symmetrical with respect to a plane intersecting them in the middle, being in particular of rectangular shape, as illustrated in FIG. 7a, or rectangular with an end refined symmetrically with respect to a median plane intersecting them. in the middle, as shown in Figure 7b.
• the sectors 4a and the housings 8 have a shape corresponding to that of the magnets, and the shape of the sectors 4a toward their free end closest to the shaft corresponds to the shape of the grooves 2a, as illustrated in FIG. 5.
• Each housing 8 may have a radial dimension / greater than that of the corresponding magnets. More particularly, each housing 8, as illustrated in FIGS. 3 to 6, may comprise a main portion 8a whose radial dimension corresponds to that of the associated magnet 7, and an end portion 8b radially internal to the magnet 7. as shown in Figure 6.
• the main portion 8a of a housing has for example a shape that corresponds substantially to that of the magnet 7, in cross section.
• a magnet 7 has in cross section two radial edges 34 which are parallel to one another on a first portion 7a of the cross section of the magnet, and two radial edges 35 converging on one side. towards the other towards the axis of rotation on a second portion 7b of the cross section of the magnet, and the housing 8 has on the main portion 8a opposite edges 30 of corresponding shape, parallel to each other. another along the first portion 7a and opposite edges 31 converging along the second portion 7b of the magnet.
• the magnets are thus asymmetrical each relative to a respective median plane S.
• Two consecutive magnets are placed symmetrically to each other by relative to a plane P passing between them, as shown in Figure 4.
• the planes P and S are planes extending both radially and longitudinally. Thus, two consecutive magnets are placed inverted in the housing of the sheets.
• two consecutive housings 8 are symmetrical to each other with respect to the plane P passing between them.
• the two consecutive edges 31 of two consecutive housings on the second portion 7b of the magnets are in the exemplary embodiment shown parallel to each other once in two when one moves around the rotational axis of the rotor and defines an end sheet portion 4c 'of the sector 4a having parallel edges.
• a convergent edge 31 of a housing and a consecutive convergent edge 31 of the subsequent housing can form with a radial plane of the rotor passing in their middle two equal angles.
• ends of sectors 4c 'with parallel edges 31 alternate with ends of sectors 4c "with convergent edges 31 when moving around the axis of rotation of the rotor, as can be seen in FIG.
• the housing 8 further has an end portion 8b which is delimited laterally by convergent opposite edges 32 towards each other in the direction of the axis of rotation.
• the opposite edges 32 may be rectilinear or not. They can for example be curved.
• the edges 32 have the shape of a involute of circle, so that the profile of the sheet corresponds to the profile of the corresponding groove 2a.
• the edges 32 open into the central opening of the rotor. These convergent opposing edges 32 of the second portion cooperate with the shaft to allow driving of the rotor mass.
• the grooves 2a extend radially beyond the permanent magnets.
• the permanent magnets extend radially beyond the flutes.
• the grooves 2a thus cooperate with a sheet portion which is not radially adjacent to one or more magnets.
• the grooves 2a can project into the stack between two consecutive permanent magnets.
• the flutes extend radially at least partially between the permanent magnets. If necessary, the grooves can come directly into contact with the magnets.
• the rotor mass can be configured to allow the placement of the magnets in the stack of magnetic sheet layers in one direction, so as to play the role of polarizer during assembly.
• All permanent magnets may have an M mark to differentiate the two longitudinal end faces of a magnet from one another. For example, as illustrated in FIG. 3, when the rotor is observed along its axis of rotation by one of its ends, the presence of the mark on one magnet out of two is observed, and it is the same when the rotor is observed on the other side. This result is due to the fact that in the example described two consecutive housings are different and symmetrical with respect to each other.
• a synthetic material can be injected into the housings 8, so as to block the magnets in the housing 8 and / or ensure the cohesion of the sheet package.
• the material used is for example an epoxy resin or a thermoplastic material.
• the Locking of the magnets 7 can also be effected by clamping under the action of the centrifugal force.
• the sheets can be made with holes to allow the passage of connecting rods of the laminations of the rotor mass.

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Iron Core Of Rotating Electric Machines (AREA)
• Permanent Field Magnets Of Synchronous Machinery (AREA)

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• 2011
  • 2011-11-18 FR FR1160511A patent/FR2983007B1/fr not_active Expired - Fee Related
• 2012
  • 2012-11-16 WO PCT/IB2012/056502 patent/WO2013072892A2/fr active Application Filing
  • 2012-11-16 EP EP12812374.2A patent/EP2781007A2/de not_active Withdrawn

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