Classifications

• • 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
  • H02K21/02—Details
  • H02K21/04—Windings on magnets for additional excitation ; Windings and magnets for additional excitation
  • H02K21/042—Windings on magnets for additional excitation ; Windings and magnets for additional excitation with permanent magnets and field winding both rotating
  • H02K21/044—Rotor of the claw pole type

Definitions

• the invention proposes an electric machine rotor comprising at least one magnetic element which is arranged between two adjacent teeth, and which is made in several parts.
• the invention more particularly proposes a rotating electric machine rotor which comprises two pole wheels, each of which extends generally radially with respect to the main axis of the rotor, and comprises a series of axial teeth, each tooth of which extends axially towards the interior from the associated pole wheel, towards the other pole wheel, so that each tooth of a pole wheel is located in the space between two consecutive teeth of the other pole wheel and at least one element magnetic longitudinal main orientation which is arranged transversely between two adjacent teeth respectively belonging to each pole wheel, and which comprises at least one magnet.
• the rotor comprises magnets arranged transversely between the axial teeth.
• the main function of magnets is to reduce magnetic flux leakage at the gap between two adjacent teeth, as well as to enhance magnetic flux by creating a clean magnet flux.
• the general magnetic properties of the rotor are determined in part by the magnets.
• the number of magnets placed in a rotor is variable and depends on the characteristics desired for the rotating electrical machine. It is thus possible to produce machines having a different number of magnets. Thus, when performing two sets of rotors between which only the number of magnets differs, the modifications of the assembly assembly of the rotors for the change of series could be too important to be profitable. This is why it is generally preferred to make rotors to keep the same number of magnets for all sets of rotors. As a result, the rotors in some series have more magnets than necessary.
• the magnetic flux produced by the magnets that are mounted on these rotors is then greater than that required, and the rotor performance is not optimized with respect to its intended use.
• the object of the invention is to propose a rotor comprising a magnetic element mounted between two adjacent teeth and whose value of the magnetic flux created by this magnetic element is optimized for the intended use of the electric machine.
• the invention provides a rotor characterized in that the magnetic element comprises at least one support wedge made of a non-magnetic material which is mounted on a transverse end face of the magnet, and means connecting the wedge with the magnet.
• the magnetic element comprises two spacers distributed transversely on either side of the magnet; - The magnetic element comprises two magnets distributed transversely on either side of the wedge;
• the magnetic element comprises an outer shim which is mounted on the outer radial end face of the magnet;
• the dimensions of the magnet and the dimensions of the wedge are determined as a function of the dimensions of the magnetic element and as a function of the overall magnetic properties of the magnetic element; the ratio of the width of the magnet to the width of the magnetic element is between 0.4 and 1;
• the wedge is bonded to the magnet by means of a layer of adhesive arranged between the wedge and the magnet;
• the shim is bonded to the magnet by overmolding non-magnetic material around at least a portion of the magnet;
• the wedge is made integrally with the connecting means.
• the lateral faces of the teeth of the pole wheels each advantageously comprise a groove extending in the longitudinal direction of the lateral faces.
• the magnet is for example made at least partially of rare earth.
• the shim can be full so that no air passage is formed between the magnet and the side face of the tooth of the polar wheel.
• the shim can be arranged to form at least one air passage between the magnet and the side face of the tooth to allow cooling of the magnet.
• the shim can be made at least partially of thermosetting or thermoplastic material.
• the wedge is made at least partially of aluminum.
• FIG. 1 is a schematic representation in perspective of a rotor comprising magnetic elements
• FIG. 2 is a view on a larger scale in section along a transverse radial plane of the rotor represented in FIG. 1, showing the structure of the magnetic element;
• - Figures 3 to 5 are views similar to that of Figure 2, showing alternative embodiments of the magnetic element;
• FIG. 6 represents the evolution of the "B / Br" ratio as a function of the "La / Lg” ratio at 20 ° C. and 120 ° C.
• FIG. 7 shows the magnetic characteristic of the magnet belonging to the magnetic element.
• FIG. 1 shows a rotor 10 of a rotating electrical machine which is mounted integral with a central shaft (not shown) rotating about the main axis A of the rotor 1 0.
• the rotor 10 is a claw rotor, which comprises in particular two pole wheels 12 axially juxtaposed and each having a radial flange 14 of annular shape provided at its outer periphery with claws 1 6.
• An excitation winding (not shown) is implanted axially. between the flanges 14 of the pole wheels 12.
• Each claw 16 has a root portion 18 which is extended at its outer periphery by a tooth 20 of generally axial orientation.
• An annular air gap exists between the outer peripheral face 20e of the teeth 20 and the inner periphery of the body of the stator 16.
• the teeth 20 are generally trapezoidal in shape and are directed axially towards the flange 14 of the other pole wheel 12, the tooth 20 of a pole wheel 12 penetrating the space between two consecutive teeth 20 of the other pole wheel 12, so that the teeth 20 of the pole wheels 12 are interlocked.
• each tooth 20 has two lateral faces 22, each of which extends parallel to and at a distance from a lateral face 22 facing a second adjacent tooth 20 and belonging to the other wheel.
• polar 12
• a first tooth 20 belonging to a pole wheel 12, and a second tooth 20 belonging to the other wheel 12, each having a side face 22 opposite the side face 22 of the other tooth 20 will be referred to as two adjacent teeth 20.
• the rotor 10 comprises magnetic elements 24 interposed between two adjacent teeth 20, which reduce the leakage of magnetic flux at the space between two adjacent teeth 20, and which contribute to strengthening the magnetic flux.
• the number of these magnetic elements 24 is determined so that it is smaller than the number of poles of the rotor 10 and that their arrangement is symmetrical with respect to the axis of the rotor 10. It is for example provided four pairs of magnetic elements 24 for eight pairs of poles.
• the side faces 22 vis-à-vis the two teeth 20 each comprise a groove 26, or groove, which extends in the longitudinal direction of the side face 22
• the section of each groove 26 in a transverse vertical plane is U-shaped open transversely to the other groove 26, and the groove 26 has a vertical bottom 26a and two transverse wings 26b which are here parallel.
• the two grooves 26 of the two adjacent teeth 20 thus define a longitudinal housing in which the magnetic element 24 is housed.
• each magnetic element 24 is made of several parts, and it comprises at least one permanent magnet 28, at least one support wedge 30, and means for connecting the support wedge 30 with the permanent magnet 28.
• Each magnet 28 is conventionally made by sintering magnetic powder or by machining a block of magnetic material.
• Each support wedge 30 is made of a non-magnetic material which is defined in such a way that the support wedge 30 has no influence on the magnetic properties of the magnetic element 24.
• the support wedge 30 is made of plastic or aluminum material.
• the spacer 30 contributes to the creation of an additional gap.
• the shim 30 is mounted on a vertical end face 28a opposite the magnet 28. After the assembly of magnets 28 and wedges
• the magnetic element 24 is then placed in a magnetic field so as to magnetize the magnetic element 24.
• the magnetic element 24 is of generally parallelepipedal shape, as well as the magnet 28 and the spacer 30.
• the magnetic element 24 comprises a single magnet 28 and a single shim 30, which are each arranged at a transverse end of the magnetic element 24.
• the magnet 28 and the spacer 30 are each received in an associated groove 26.
• FIG. 3 shows a second embodiment of the invention according to which the magnetic element 24 comprises two magnets 28 and a single shim 30.
• the two magnets 28 are arranged transversely on either side of the spacer 30, and each magnet 28 is received in an associated groove 26.
• FIG. 4 shows a third embodiment of the invention according to which the magnetic element 24 comprises two shims 30 and a single magnet 28.
• the two shims 30 are arranged transversely on either side of the magnet. the magnet 28, and each shim 30 is received in a groove 26 associated.
• the realization of the magnetic element 24 from two elements having different magnetic properties makes it possible to adjust the overall magnetic flux created by the magnetic elements 24.
• the overall magnetic flux created by the magnetic elements 24 corresponds to the sum of the magnetic fluxes created by each magnetic element.
• the magnetic flux created by each magnetic element is equal to the product of the operating flow density "B" of the magnetic element by the surface "S" facing the magnet of the magnetic element and the surface of the claw.
• “B” is determined from the magnetization curve of FIG. 7 and corresponds to the ordinate of contact point C between the magnetic characteristic of magnet 28 (curve ⁇ ) and the straight line ⁇ whose slope is notably linked to the gaps of the main path crossed by the flow and to the width "La" of the magnet 28.
• the air gaps include, for example, the space between the outer peripheral face 20e of the teeth 20 and the inner periphery of the body of the stator 16.
• each magnet 28 the greater the transverse dimension "La" of each magnet 28 is important, the more the line ⁇ tends towards the ordinate axis.
• the Magnetic operating density "B” of the magnet then tends to "Br” and the magnetic flux created by the magnetic element 24 is increased.
• the dimensions of the magnet 28, or two magnets 28 forming the magnetic element 24 are determined according to the value of the magnetic flux that is desired.
• the dimensions of the magnetic element 24, mainly its transverse width "Lg” are determined according to the dimensions of the two grooves 26, so that the transverse width "Lg" of the magnetic element is substantially equal to the distance between the funds 26a of the two throats 26.
• each shim 30 are then determined according to the dimensions of each magnet 26, so as to adjust the dimensions of the magnetic element 24 to the dimensions of the housing defined by the two grooves vis-à-vis.
• FIG. 6 shows the variation of the ratio "B / Br" as a function of the ratio "La / Lg".
• B represents the density of the operating flow of the magnetic element 24
• Br represents the density of the remanent flux
• La represents the width of the magnet
• Lg represents the transverse width of the magnetic element 24.
• the density of the remanent flux corresponds to the density of the permanent flux remaining in the magnet at the end of the magnetization phase.
• The of the magnet 28 according to the desired magnetic properties of the magnetic element 24, that is to say according to the density of the desired operating flow.
• the evolution of the ratio "B / Br” as a function of the ratio "La / Lg” is different according to the temperature at which the magnetic element 24 is subjected.
• the characteristic of the curve is linear.
• the curve is initially nonlinear when the ratio La / Lg is small, then becomes linear. Indeed, the characteristic of the magnet belonging to the magnetic element degrades when the temperature increases. This degradation is accentuated when the La / Lg ratio is low. But during the operation of the machine, the temperature of the magnet is close to T2.
• the minimum operating flow density "B" is set by the linear operating limit of the magnet at temperature T2.
• the T2 curve it is easier to determine the dimensions of the magnet 28 as a function of the density of the desired operating flow "B" and the distance "Lg" available between the two grooves 26. It will be understood that when the magnetic element 24 comprises several magnets 28, as for example in the embodiment shown in FIG. 3, the width "La" of magnet 28 which is determined according to the embodiments described above, corresponds to the sum of widths of all the magnets 28 of the magnetic element 24.
• the use of the magnetic element 24 is particularly advantageous when it is desired to mount an element between two adjacent teeth whose density value operating flow is less than the value of the operating flow density of a full magnet mounted between the two teeth.
• At least one shim 30 then makes it possible to adapt the dimensions of the magnetic element 24 to the dimensions of the grooves 26.
• the shim 30 being made of a non-magnetic material, it contributes to the creation of an additional gap.
• a shim 30 in the magnetic element 24 also makes it possible to add certain mechanical properties to the magnetic element 24 with respect to a solid magnet.
• a magnet 28 is a relatively fragile element.
• the shim 30 is made of an elastically deformable material. Therefore, the use of a shim 30 of elastically deformable material, to produce the magnetic element 24 makes it possible to compensate for certain dimensional deviations of the rotor 10 which would result for example in a radial offset of two grooves 26, that is to say a transverse misalignment, or a variation of the distance between the bottoms 26a of the two grooves 26.
• the support wedge 30 is connected to each magnet 28 by means of an adhesive layer 32.
• the adhesive layer 32 which links the shim 30 to the magnet 28 is also made of a non-magnetic material.
• the adhesive layer 32 is relatively flexible, so that it also allows the magnetic element 24 to adapt the shape of the magnetic element 24 to the possible dimensional deviations of the rotor 10.
• a material not magnetic is overmolded around the magnet 28 and around the hold
• the shim 30 is formed integrally with the connecting means, that is to say that the shim 30 is made at least partly by overmoulding non-magnetic material around the liner. magnet 28.
• FIG. 5 shows a variant embodiment of the invention according to which the magnetic element 24 has an outer shim 34 which extends transversely over the entire width
• the outer shim is arranged radially between each magnet 28 and the upper transverse wings 26b of the grooves 26.
• each magnet rests against the outer shim 34, which then dampens the compression forces of the magnet 28 resulting from the centrifugal force and any deformations of the pole wheels 12.
• the magnetic element 24 is adapted to be mounted on a rotor
• the rotor which has just been described comprises magnetic elements 24 which are of parallelepipedal shape. It will be understood that the invention is not limited to this embodiment and that the magnetic elements 24 may be of different shape, for example they may have a diamond-shaped cross section.

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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)
• Synchronous Machinery (AREA)

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• 2005
  • 2005-12-21 FR FR0513028A patent/FR2895165B1/fr not_active Expired - Fee Related
• 2006
  • 2006-11-24 WO PCT/FR2006/051225 patent/WO2007077370A1/fr not_active Ceased
  • 2006-11-24 US US12/095,541 patent/US8264119B2/en not_active Expired - Fee Related
  • 2006-11-24 CN CN2006800487069A patent/CN101346872B/zh not_active Expired - Fee Related
  • 2006-11-24 BR BRPI0620137A patent/BRPI0620137B8/pt not_active IP Right Cessation
  • 2006-11-24 JP JP2008546534A patent/JP2009521198A/ja active Pending
  • 2006-11-24 EP EP06842036A patent/EP1964239A1/de not_active Withdrawn

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