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
  • H02K1/2793—Rotors axially facing stators
  • H02K1/2795—Rotors axially facing stators the rotor consisting of two or more circumferentially positioned magnets
• • 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
  • H02K1/28—Means for mounting or fastening rotating magnetic parts on to, or to, the rotor structures
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02K—DYNAMO-ELECTRIC MACHINES
  • H02K21/00—Synchronous motors having permanent magnets; Synchronous generators having permanent magnets
  • H02K21/12—Synchronous motors having permanent magnets; Synchronous generators having permanent magnets with stationary armatures and rotating magnets
  • H02K21/24—Synchronous motors having permanent magnets; Synchronous generators having permanent magnets with stationary armatures and rotating magnets with magnets axially facing the armatures, e.g. hub-type cycle dynamos

Definitions

• the present invention relates generally to electrical machines with axial flow.
• the invention finds a particularly advantageous application in the electric motors of electric or hybrid motor vehicles.
• An axial flow electric machine generally comprises two stators and a rotor, air gaps separating these two types of elements.
• the rotor carries a series of permanent magnets, while a series of coils is carried by the stators.
• the rotor When the coils are supplied with an electric current, the rotor, which is secured to the output shaft of the motor, is subjected to a torque resulting from the magnetic field (the magnetic flux created being an axial flux for an electric machine axial flow).
• a judicious way to increase the mechanical power delivered by an electric motor is to increase the rotational speed of the rotor. It is also possible to increase its torque, but this has certain disadvantages such as an increase in the weight and / or the size of the engine or the increase in losses due to the Joule effect.
• Permanent magnets the shape of which is adapted to the shape of the notches, are inserted into these notches.
• the edges of the permanent magnets are grooved so that they can fit over ribs provided along the edges of the notches.
• a layer of glue is placed in the groove to ensure the fixing.
• the main disadvantage of such a rotor lies in the possibility of detachment of the permanent magnets from the body of the rotor in the event of rotation of the rotor at very high speed. Indeed, the permanent magnets undergo strong radial stresses, due to the centrifugal force when the rotor is rotating about its axis of rotation.
• the present invention proposes to strengthen the fixing of each permanent magnet in the body of the rotor.
• a rotor as defined in the introduction, in which at least one of the edges of the notch extends in length along an average line and has a cross section at this average line of which the shape varies along the mean line so as to form at least a first relief and in which at least part of one of the edges of the permanent magnet, facing said at least one of the edges of the notch, has at least one second relief of corresponding shape, in negative, to match the shape of said at least one first relief.
• a larger bonding surface between the permanent magnet and the body ensures better maintenance of the assembly and in particular better resistance to centrifugal forces.
• the normal to the bonding surface having a direction which is also variable, the stresses due to the centrifugal forces are distributed between tensile stresses and shear stresses. The effectiveness of the bonding is thereby increased. The probability of detachment of the permanent magnets from the body is then greatly reduced.
• a gap is provided between said at least one of the edges of the notch and said at least one of the edges of the permanent magnet, said gap extending over at least part of the length of said at least one edge of the notch and over only part of the thickness of said body.
• the effect of a layer of glue or varnish enveloping the rotor is greatly improved.
• the gap increases the thickness of the layer of glue or varnish between the edge of the notch and the edge of the permanent magnet.
• This layer is thicker and therefore more elastic, this makes it possible to better absorb the slight movements of the permanent magnet relative to the body due to centrifugal forces.
• said permanent magnet comprises a magnetic body and a casing which at least partially surrounds the magnetic body, said magnetic body has a shape in relief corresponding to that of said at least one second relief. Adapting the shape of the magnetic body to the shape of the edge of the notch makes it possible to maximize the volume of the magnetic body in relation to the total volume of the permanent magnet (and therefore in relation to the volume of the rotor) and thus to improve performance magnets of the rotor.
• a hoop surrounds the periphery of the assembly formed by said body and said at least one permanent magnet, and, in the disassembled state, the internal diameter of the hoop is partly less than the external diameter of said assembly.
• said at least one of the edges of the notch has a plurality of first reliefs and said at least one of the edges of the permanent magnet has a plurality of second reliefs of corresponding shape, in negative, to match the shape of the plurality of first reliefs;
• notch Said one of the edges of the notch has a rib or a groove extending over at least part of its length and said permanent magnet respectively has a groove or a rib of corresponding shape (to preferably form a tight fit);
• said at least one notch extends over the entire thickness of said body.
• Figure 1 is a schematic front view of a machine rotor electric.
• Figure 2 is a schematic exploded perspective view of part of the rotor of Figure 1 showing a permanent magnet before it is inserted into a notch.
• Figure 3 is a sectional view along the plane A-A of Figure 2.
• Figure 4 is a sectional view along the plane B-B of Figure 2.
• Figure 5 is a sectional view along the plane C-C of Figure 1.
• Figure 6 is a sectional view along the plane D-D of Figure 1.
• Figure 7 schematically illustrates Figure 6 before assembly of the rotor.
• FIG. 1 there is shown a rotor 100 of an electric machine.
• the rotor 100 includes a body 110, a plurality of permanent magnets 130, and a hoop 150.
• the body 110 has the overall shape of a disc, in the sense that it is substantially circumscribed to a cylinder of revolution about an axis hereinafter called axis of rotation A1. It has a height (dimension of the body along the axis of rotation A1) which is much less than the diameter. In the following description, this height is called the thickness of the body 110.
• the body 110 thus has two plane circular faces, mutually parallel and perpendicular to the axis of rotation A1 of the rotor 100, one of the two faces being visible in the figure. 1.
• the body 110 has a central recess adapted to receive a transmission shaft extending along the axis of rotation A1.
• the rotor 100 is intended to be fixed to this transmission shaft which it is intended to drive.
• the body 110 can for example be made from aluminum, steel, iron, titanium or an alloy containing these metals. It is for example produced by a stack of metal sheets with a thickness less than or equal to a millimeter. These metal plates are here curved and stacked radially. They extend over the entire height of the body 101. Thus, losses in the stator due to eddy currents are limited.
• the body 110 is preferably made of a composite material reinforced with glass or carbon fibers.
• the body is composed of three layers, two outer layers 112, 114 and a central layer 113, having generally identical shapes. These three layers, stacked along the axis of rotation A1, form body 110. Alternatively, body 110 may be machined from a single block.
• the body 110 has a plurality of notches 120 recessed in its peripheral edge.
• the body 110 has twelve identical notches 120.
• the notches 120 are distributed evenly over the entire periphery of the body 110. This makes it possible to ensure a good balance of the rotor 110 when the latter is rotating.
• the body 110 comprises a central hub and a plurality of branches extending from the hub in substantially radial directions with respect to the axis of rotation A1.
• the branches become thinner towards the periphery of the rotor 100.
• the branches, 12 in number in FIG. 1 are all identical and regularly distributed around the hub so as to be two separate. Two by one space, each pair of adjacent branches then defines one of the notches 120.
• these notches are thus radially open towards the outside, that is to say towards the periphery of the rotor 100.
• each notch 120 preferably extends over the entire thickness of the body 110. This has the advantage of providing two opposing working surfaces. Such a rotor 100 can thus for example be framed by two stators to provide more mechanical power.
• Each notch 120 has an overall U shape with spaced arms, with two side edges 121 of substantially radial extension and a bottom here called inner edge 122.
• the inner edge 122 is rectilinear (it is a flat surface).
• the inner edge 122 may be curved, for example with the same radius of curvature as the body 110.
• the notch 120 could have a V-shape and have only two side edges, the inner edge 122 then being assimilated to the edge formed by the contact of the two side edges 121.
• each notch 120 generally has three straight edges including two side edges 121 which move away from each other from the center of the body 110 to the outside of the latter.
• This geometry allows a simple radial insertion of the permanent magnets 130 in the notches 120, by a simple movement of engagement in a radial direction A2 (relative to the axis of rotation A1).
• the side edges of a notch 120 are each provided with a groove 160 extending lengthwise in a substantially radial direction.
• Each groove 160 has a U-shaped cross section and is delimited between two side walls 161. As shown in Figures 3 and 4, the side walls 161 defining this U are here formed by the two outer layers 112, 114 of the body 110.
• Each groove 160 is here located halfway between the two circular faces of the body 110.
• the inner edge 122 may have a relief, for example formed by a difference in radial extension of the outer layers 112, 114 relative to the central layer 113.
• the inner edge 122 may therefore have a groove similar to the groove 160 of a side edge 121 of the notch 120.
• the permanent magnet 130 then has a complementary shape to fit into this relief.
• Each groove 160 is designed to interlock with a rib 170 provided in correspondence with the permanent magnet 130, projecting from its side edges.
• This groove and rib type assembly ensures a high resistance of the rotor 100 with respect to the axial forces undergone by the permanent magnets 130 when the electric motor is in operation and the permanent magnets 130 are attracted towards the coils of the stator.
• each rib protrudes from the side edge of the notch and that each groove extends recessed into one of the side edges of the permanent magnet 130.
• Each side edge 121 of the notch 120 extends in length (here in a direction orthogonal to the axis of rotation A1) along a mean line D1.
• the mean line D1 is a straight line.
• the mean line could be a curve.
• the mean line D1 is defined here as the line passing on average as close as possible to the geometric centers of the surfaces formed by the sections of the lateral edge (the section plane considered being orthogonal to the radius along which this edge extends substantially) .
• the mean line can for example be defined as a linear regression line on the positions of the geometric centers of the surfaces formed by the sections of the lateral edge.
• Each permanent magnet 130 has a shape adapted to the notch 120 in which it is inserted. As shown in Figures 1 and 2, each magnet permanent 130 here therefore has a generally trapezoidal shape. Each permanent magnet 130 has a thickness (dimension along the axis of rotation A1) substantially equal to the thickness of the body 110.
• Each permanent magnet 130 thus has two magnet edges 131 located opposite the side edges 121 of the notch 120 in which it is inserted.
• the edges of the magnet 131 have an almost identical geometry, in negative, to the geometry of the side edges 121.
• the edges of the magnet 131 are in particular provided with a rib 170 which fits together, except for an assembly clearance, in the groove 160.
• each notch 120 extending in length along the mean line D1 associated with it, has a cross section to this mean line, the shape of which varies from along the middle line so as to form at least a first relief 140, and at least part of the edge of the magnet 131 in contact with the lateral edge 121 has a second relief 141 of corresponding shape, in negative, to match the shape of the first relief 140.
• the two side edges of the notches 120 are identical.
• FIG. 3 there is shown a first section plane AA of the side edge 121 of Figure 2 which shows a first cross section at a first relief 140.
• Figure 4 there is shown a second section plane BB of the side edge 121 of FIG. 2 which represents a second transverse section in a zone devoid of a first relief 140.
• the shape of the cross section to the mean line D1 varies along the mean line D1 between the two section planes A-A and B-B.
• the side walls 161 defining the groove 160 are higher for the first cross section than for the second cross section.
• the groove 160 is deeper at a first relief 140 than in an area without a first relief 140.
• the shape of the cross section at the mean line D1 is a U shape, the depth of which varies linearly by section along the mean line D1 between a minimum depth and a maximum depth.
• the reliefs 140, 141 increase the contact surface between the permanent magnet 130 and the body 110, more precisely between the side edge 121 of notch 120 and magnet edge 131.
• a layer of glue 190 is disposed between the permanent magnet 130 and the body 110 at the notch 120 (on the body 110 and / or on the permanent magnet 130 ).
• the purpose of this layer of glue 190 is to ensure that the permanent magnet 130 is held in the notch 120 when the rotor 100 is rotating and the permanent magnet 130 is subjected to significant centrifugal forces (all the more as the rotation speed is high).
• the directions normal to the contact surface that is to say to the bonding surface, are varied. This makes it possible to better distribute the stresses to which the adhesive layer is subjected between tensile stresses and shear stresses when the rotor 100 is rotating.
• the permanent magnet 130 is mainly retained by the lateral grooves 160.
• each side edge 121 has a plurality of first reliefs 140 and each magnet edge 131 has a plurality of corresponding second reliefs 141.
• the bonding surface is thus further increased which increases the retention of the permanent magnet 130 in the notch 120.
• each side edge 121 has five first reliefs 140 on each of the two side walls 161 defining the groove 160.
• the first reliefs 140 give the end faces of the side walls 161 of the groove 160 a zigzag or sawtooth shape which consists of broken lines.
• each edge of the magnet 131 has ten second reliefs 141: five on each side of the rib 170.
• first reliefs 140 are reliefs projecting from the end faces of the side walls 161 of the groove 160 and the second reliefs 141 are recesses in the magnet edge 131.
• the first reliefs 140 located on the side edges 121 of the notches 120 could be recesses and the second reliefs 141 could protrude from the edge of the magnet 131 Provision can also be made for the first reliefs 141 to include both projecting reliefs and recesses and for the second reliefs 141 to include corresponding recesses and projecting reliefs.
• each first relief 140 has flat faces. This implies that the corresponding second reliefs 141 also have flat faces.
• each first relief 140 has two rectangular end faces connected together by a ridge and two triangular side faces (here isosceles triangles).
• the magnet edge 131 is in contact along its entire length with the side edge 121 of the notch 120.
• the contact area between the permanent magnet 130 and the notch 120 is maximum.
• the permanent magnet edge 131 is in contact over its entire length with the side edge 121 of the notch 120 means that the side edge 121 has a single contact surface contiguous with the magnet edge 131 which is associated with it, this contiguous surface extending from the inner edge 122 to the periphery of the body 110.
• the interlocking can then be qualified as complete.
• each first relief 140 is oriented so that the permanent magnet 130 can be engaged in the notch 120 in a radial direction A2.
• each first relief 141 is always oriented towards the outside of the notch 120 (towards the periphery), as opposed to the inner edge 122.
• the surface of each first relief 141 is thus never oriented towards the interior edge 122.
• the surface of each first relief 141 is orthogonal with the surface of the interior edge 122.
• the surfaces of each first relief 141 are oriented towards the outside of the notch 120.
• outside of the notch is also meant, at the extreme limit, an orientation according to a direction perpendicular to the radial direction A2.
• a gap 143 is located over at least part of the length of each side edge 121, between the body 110 and the permanent magnet 130. This interstice extends over only part of the thickness of body 110.
• this gap 143 provision can be made, for example, for the height of the rib 170 provided to project from each edge of the magnet 131 to be slightly greater than the depth of the corresponding groove 160.
• the first 140 and second 141 reliefs face each other at a short distance.
• the outer glue layer can be deposited in the form of an aerosol by spraying or else by immersion of the rotor. 100 in a bath of liquid glue.
• the gap 143 increases the thickness of the layer of adhesive between the side edge 121 and the permanent magnet 130 (that is, between the side edge 121 and the magnet edge 131).
• the glue layer is thicker and therefore more elastic. This makes it possible to better absorb the slight movements of the permanent magnet 130 relative to the body 110 when it is subjected to centrifugal forces.
• the glue may warp slightly without cracking or breaking.
• each permanent magnet 130 has a plane inner edge 132 and an outer edge 180.
• the inner edge 132 is applied against the inner edge 122 of the notch 120.
• the outer edge 180 is flush with the periphery of the body 110.
• the outer edge 180 is curved and has the same radius of curvature as the body 110.
• the peripheral surface of the rotor 110 is cylindrical.
• Each permanent magnet 130 has a casing 135 and a magnetic body 136.
• the magnetic body 136 is the part of the permanent magnet 130 which generates a static magnetic field. It can for example be composed of a neodymium iron boron or samarium cobalt assembly.
• each magnetic body 136 is composed of a plurality of unit magnets whose length extends over the entire thickness of the permanent magnet 130 and whose section is hexagonal. Using a plurality of individual magnets reduces Focault current losses compared to a single magnet of the same size.
• the unit magnets could have a different section, for example square, triangular or round.
• the envelope 135 surrounds the magnetic body 136 at the edges of the notch 120 and the periphery of the body 110.
• the envelope 135 does not cover the magnetic body 136 at its main faces.
• the envelope 135 is preferably made of a non-magnetic material.
• the envelope 135 can be made of plastic or resin, for example an epoxy resin.
• the second reliefs 141 are formed by the envelope 135.
• the magnetic body 136 preferably has reliefs (at the edges of the magnet 131) of shapes corresponding to the second reliefs 141.
• the magnetic body 136 of each permanent magnet 130 has a sawtooth profile.
• the magnetic body 136 also has a recess at the level of this second relief 141. Closely following the shape of the second relief 141 makes it possible to maximize the volume of the magnetic body 136 relative to the permanent magnet 130.
• This adaptation of the magnetic body 136 to the second reliefs 141 can be achieved by arranging the individual magnets according to the shape of the notch 120.
• the rotor hoop 150 shown in Figure 1, surrounds the periphery of the body 110 and the permanent magnets 130 by their outer edges 180.
• the role of the hoop 150 is to provide an additional holding means (against the forces centrifugal) for the permanent magnets 130 when the rotor 100 is rotating.
• the hoop 150 is made of composite materials such as glass fibers, carbon fibers or polymer fibers embedded in a resin.
• the hoop 150 has an annular shape.
• the internal diameter of the hoop 150 is strictly less than the external diameter of the body 110.
• the hoop 150 When it is put in place, the hoop 150 then undergoes a slight elastic deformation. Thus, the hoop 150 is preloaded and provides more support to the permanent magnets 130.
• each permanent magnet 130 has a different shape, with three faces here.
• a first face 181 extends along a cylindrical surface of revolution around the axis of rotation A1, in the extension of the periphery of the body 110 while a second face 183 extends along a cylindrical surface of revolution of diameter more big.
• the hoop 150 has an internal surface adapted to that of the external edges 180 of the magnets.
• the inner surface of the hoop 150 therefore also has three faces.
• each permanent magnet prefferably has a single frustoconical surface of revolution around the axis of rotation.
• the internal surface of the hoop is then a corresponding frustoconical surface.
• the profile of the hoop then has the shape of a rectangular trapezoid.
• the face of the hoop 150 of larger diameter has a diameter equal, except for a clearance, to the outer diameter of the body 110 and the first faces 181 of the outer edges 180 of the permanent magnets 130.
• the hoop 150 can thus be put in placed by this side of the body 110.
• the hoop 150 then deforms as it is inserted because the other faces of the inner surface of the hoop 150 have diameters smaller than the outer diameter of the body 110.
• the hoop 150 is itself also glued to the body 110 and to the permanent magnets 130. Thanks to this hoop 150 which, in the disassembled state, has an internal diameter partly smaller than the external diameter of the body 110, it is possible to have a small amount of glue which is distributed during the installation of the hoop 150.
• Figure 6 illustrates the rotor 100, along the section plane D-D of Figure 1, once the permanent magnet 130 has been inserted into the notch 120 and once the band 150 in place.
• a first layer of glue 190 is distributed between the notch 120 and the permanent magnet 130.
• the first layer of glue 190 is in particular distributed in the gap 143 between the notch edge 121 and the permanent magnet 130.
• a second layer of adhesive 191 is distributed between the permanent magnet 130 and the hoop 150.
• Figure 7 illustrates, still along the sectional plane D-D of Figure 1, the rotor 100 before the permanent magnet 130 is inserted into the notch 120 and before the band 150 is in place.
• the first layer of glue 190 is distributed in the groove 160.
• the second layer of glue 191 is distributed at the level of the third face 182 of the outer edge 180 of the permanent magnet 130.
• the rotor 110 is assembled by a radial insertion of the permanent magnet 130 in the notch 120.
• the hoop 150 can be put in place at the same time or subsequently.
• the hoop 150 When it is put in place, the hoop 150 translates in the direction of the axis of rotation A1.
• the establishment of the hoop 150 here makes it possible to distribute the second layer of glue 190 along the outer edge 180.
• the internal dimensions of the hoop 150 mean that its installation also makes it possible to constrain l 'permanent magnet 130 in the direction of the notch 120. This constraint allows or facilitates the insertion of the rib 170 in the groove 160.
• the first layer of adhesive 190 is formed. distributed along the edge of notch 121.
• a varnish or an external layer of glue enveloping the rotor 100 can be deposited. This can make it possible to fill in the spaces, between the notch 120 and the permanent magnet 130 and between the permanent magnet 130 and the hoop 150, where the first layer of glue 190 and respectively the second layer of glue 191 would not have come together. distributed. In particular, this can make it possible to fill the gap 143 with glue.
• the shape and orientation of the first reliefs 140 and of the second reliefs 141 allow complete engagement of the permanent magnets 130 in the notches 120.
• the permanent magnets 130 may be, in one first step, inserted into the central layer 113 of the body 110.
• the ribs 170 bordering the permanent magnets 130 are in contact with the bottom of the grooves 160 provided in the notches 120.
• the outer layers 112, 114 of the body 110 are plated on either side of the central layer 113.
• the first reliefs 140 are made in these outer layers 112, 114 of the body 110 and are inserted into the second reliefs 141 made in the envelope 135 of the permanent magnets 130.
• the shape and orientation of the first and second reliefs 140, 141 is not constrained by the radial insertion of the permanent magnets 130.
• Other shape variants for the first reliefs 141 are conceivable, for example shapes blocking a radial exit of the permanent magnets 130 when the rotor 100 is rotating.

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

Applications Claiming Priority (2)

Publications (1)

Family

ID=70614189

Family Applications (1)

Country Status (5)

Family Cites Families (12)

• 2020
  • 2020-03-06 FR FR2002258A patent/FR3107999B1/fr active Active
• 2021
  • 2021-03-05 CN CN202180018036.0A patent/CN115210994A/zh active Pending
  • 2021-03-05 WO PCT/EP2021/055594 patent/WO2021176058A1/fr unknown
  • 2021-03-05 KR KR1020227034723A patent/KR20220157987A/ko unknown
  • 2021-03-05 EP EP21709023.2A patent/EP4115498A1/de active Pending

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