Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02K—DYNAMO-ELECTRIC MACHINES
  • H02K1/00—Details of the magnetic circuit
  • H02K1/02—Details of the magnetic circuit characterised by the magnetic material
• • 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
  • H02K1/12—Stationary parts of the magnetic circuit
  • H02K1/14—Stator cores with salient poles
  • H02K1/146—Stator cores with salient poles consisting of a generally annular yoke with salient poles
  • H02K1/148—Sectional cores
• • 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
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02K—DYNAMO-ELECTRIC MACHINES
  • H02K3/00—Details of windings
  • H02K3/04—Windings characterised by the conductor shape, form or construction, e.g. with bar conductors
  • H02K3/18—Windings for salient poles
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02K—DYNAMO-ELECTRIC MACHINES
  • H02K3/00—Details of windings
  • H02K3/46—Fastening of windings on the stator or rotor structure
  • H02K3/52—Fastening salient pole windings or connections thereto
  • H02K3/521—Fastening salient pole windings or connections thereto applicable to stators only
  • H02K3/522—Fastening salient pole windings or connections thereto applicable to stators only for generally annular cores with salient poles

Definitions

• Stator tooth for electric machine associated cylinder head and stator
• the present invention relates to a rotary electrical machine, in particular for an electric or hybrid motor vehicle.
• the present invention relates more particularly to a stator comprising teeth fixed on a stator yoke.
• Rotating electrical machines generate losses in the form of heat caused in particular by eddy currents.
• the magnetic field creates a heating on the one hand because induced currents called eddy currents circulate there in short-circuit and, on the other hand, because they present resistance to flow circulation.
• these conductive parts of the stator and the rotor are almost systematically made up of a stack of thin sheets electrically isolated from one another and oriented in the direction of the magnetic field.
• the efficiency of the electrical machine depends in particular on the magnetization of the rotor (s).
• the magnets irreversibly lose their magnetic property.
• eddy currents circulate in the magnets contributing to their heating.
• the rotor In a rotating axial flow electric machine with central rotor, the rotor is arranged between two stators, the rotor and the stators dissipating heat.
• Document GB2482928 discloses a rotary axial flow electric machine with central stator, that is to say in which the stator is arranged between two rotors comprising magnets.
• the rotors are arranged at the ends of the machine, they are cooled by fresh air.
• the central stator comprises a disc made of composite plastic material, supporting stator pads in compressed and sintered ferrous powder, the grains of which are coated with an electrical insulating material, which reduces their resistance to magnetic flux. crossing.
• the induced currents responsible for heating the stator are thereby reduced there.
• the rotor includes a disc having apertures arranged circumferentially and accommodating magnets.
• This configuration limits the heating of the rotor.
• the rotor is heated by the heat radiating from the stators.
• the invention relates to a stator tooth for an electric machine comprising a casing extending between a first face comprising means for fixing to a stator yoke and a second opposite face.
• the envelope houses one or more conductive materials configured to direct the magnetic flux of the machine in operation from one of said faces to the other.
• the envelope is made of stamped non-magnetic sheet.
• the first face comprises at least one tab intended to be fixed on the cylinder head.
• the second face comprises at least one flap for immobilizing in an axial direction a preassembled winding inserted between the tongue and the flap.
• the tooth further comprises a pre-assembled coil inserted on the outer peripheral surface of the envelope.
• the preassembled winding comprises a support frame on which is wound a wire comprising several strands held in an insulating envelope forming turns.
• the conductive material comprises needles extending from the first to the second face.
• the needles are made of material permeable to a magnetic field and with a grain oriented along the length of the needles.
• each needle which is not delimited by the first and the second face is coated with an insulating material.
• the gaps between the needles and the envelope are filled with glue.
• the conductive material comprises thin sheets extending from the first to the second face and stacked on top of each other.
• the gaps between the thin sheets and the casing are filled with glue.
• the tooth comprises a monobloc stud, the conductive material being produced by compacting a ferrous powder coated with electrical insulator.
• the conductive material further comprises lateral extensions extending towards the outside of the envelope and comprising recesses intended to accommodate staples fixed to the cylinder head.
• the invention also relates to a cylinder head comprising at least one stator tooth as defined above and a stator for electric machine with central rotor comprising such a cylinder head, and an electric machine with axial flow with central rotor comprising such a stator.
• FIG. 1 illustrates a sectional view of a rotary axial flow electric machine with central rotor according to the invention
• Figure 2 illustrates a view of the cylinder head and stator teeth according to the invention
• FIGS. 3 and 4 illustrate a first embodiment of a stator tooth according to the invention
• FIG. 5 illustrates a second embodiment of a stator tooth according to the invention.
• FIG. 6 illustrates a third embodiment of a tooth formed of a stator pad according to the invention.
• FIG. 1 illustrates a sectional view of an electric machine 1 rotating axial flow with central rotor in an axial direction.
• this machine is a traction motor for an electric or hybrid vehicle.
• the electric machine 1 comprises a casing 2 comprising two stators 3a and 3b of identical architecture surrounding a rotor 4 and an axis (A) coincident with the axis of rotation of the rotor 4.
• Each stator 3a and 3b is separated from the rotor by an air gap ENT.
• the rotor 4 is guided by ball bearings 5 and 6 supported by the casing 2.
• the rotor 4 comprises a hub 7 on which is fixed a disc 8 comprising openings arranged circumferentially and housing magnets 9 preferably segmented and electrically insulated to limit the currents induced in the magnets.
• the disc is preferably made of composite material, for example of fiber-reinforced polymer, thus reducing the currents of Foucault.
• the disc is preferably surrounded by a hoop to improve its mechanical strength.
• the rotor 4 is positioned axially between the stators 3a and 3b so as to obtain air gaps of equivalent thickness.
• an adjustment shim is provided on one side, for example on the right. Measurements are taken to determine the thickness of the shim.
• a spring is placed behind the bearing opposite the shim.
• the stators are centered one and the other in two half-casings and maintained in axial support by a device of studs, welded on the cylinder head 10 and of nuts distributed regularly and circumferentially on the cylinder head 10.
• stators 3a and 3b To cool stators 3a and 3b, water chambers are provided in each casing. These rooms are sealed by O-rings.
• stator 3a As the stators 3a and 3b are of identical architecture, only the stator 3a is detailed below.
• the stator 3 a comprises a cylinder head 10 on which are arranged stator teeth 1 1 all identical.
• the cylinder head 10 has a constant thickness and comprises, for example, a thin sheet whose surface is electrically insulated and wound in a spiral shape with a steel grain oriented in the winding direction.
• the cylinder head is made of non-oriented steel grain.
• the magnetic flux which must circulate between two adjacent teeth will follow the orientation given by the winding of the sheet.
• another magnetically conductive material than steel is used.
• Figures 2, 3 and 4 illustrate a view of the cylinder head 10 comprising a first preferred embodiment of a stator tooth 1 1, and a partial section of the cylinder head 10 and a stator tooth 1 1 in the direction III- III shown in Figure 2.
• the stator tooth 1 1 comprises an envelope 12 extending between a first face 13 fixed on the cylinder head 10 and a second face 14. These faces are orthogonal to the axial direction (axis of rotation (A) of the rotor).
• the casing 12 houses one or more conductive materials.
• the conductive material comprises needles 15.
• the envelope 12 is for example isosceles triangular whose vertices are rounded and whose sides of the same length are oriented so that the tooth is symmetrical with respect to a axis of symmetry (B). The vertex common to the two sides of the same length is oriented towards the axis (A).
• the needles 15 extend from the first face 13 towards the second face 14. More precisely, the needles 15 extend in the axial direction. Their length is preferably substantially equal to the axial dimension of the casing 12, itself greater than the thickness of the cylinder head 10.
• the diameter (or the dimensions of the section in the case where they are not cylindrical) of the needles is of the order of 0.5mm preferably, and preferably less than 1mm. It can be smaller than 0.5mm, and depends on the frequency of use of the rotating machine 1. For example at OOOHz, a diameter less than 0.3mm is preferable.
• the set of needles of the stator tooth 1 1 has, in an axial section, a substantially trapezoidal or triangular shape with rounded corners.
• the periphery of the envelope 12 forms a ribbon whose width extends in the axial direction between the faces 13 and 14 and the length extends angularly all around the shape drawn by the needles of the stator tooth 1 1.
• the casing 12 nevertheless comprises tongues 16 positioned perpendicular to the ribbon formed by this periphery of the casing 12, on the surface of the cylinder head 10 orthogonal to the axis (A). Similarly flaps 22 positioned perpendicular to the ribbon formed by this periphery maintain the winding 17 assembled around the ribbon.
• the envelope 12 is produced for example by stamping a non-magnetic sheet.
• the needles 15 are for example cylindrical and preferably made of a material permeable to a magnetic field and to grain oriented lengthwise, for example of magnetic steel.
• the section of the needles can be of different shape, for example polygonal.
• each needle 15 which is not delimited by the first and second faces 13 and 14 is coated with an insulating material (not shown), for example a varnish, so that the needles 15 are magnetically in contact with the yoke 10, and that a magnetic field can pass from the yoke 10 to the rotor 4 through the needles 15 and the air gap ENT.
• the needles are preferably directly in contact with the yoke 10 without insulating material separating them.
• the gaps between the needles 15 and the casing 12 are filled with glue, for example a resin (not shown).
• glue for example a resin (not shown).
• This adhesive has electrical insulating and thermal conductive properties, in addition to the bonding function.
• Insulating the needles 15 from each other and with the casing 12 makes it possible to reduce the induced currents responsible for the heating of the stator 3a.
• the first face 13 comprises the tongues 16 fixed on the cylinder head 10 so as to secure the tooth 11 on the cylinder head 10.
• Each tongue 16 is for example fixed on the cylinder head 10 by a laser weld passing through said tongue.
• the stator tooth 1 1 further comprises a preassembled coil 17 inserted on the outer peripheral surface of the casing 12.
• the preassembled winding 17 comprises a support frame 18 on which is wound a wire 19 by forming turns.
• the wire 19 preferably comprises several strands 20 held in an insulating envelope 21.
• the flow of current is improved by using several strands compared to a monobloc wire.
• the second face 14 of the casing 12 comprises the deformable flaps 22 which, when the preassembled winding 17 is engaged on the tooth 11, are pushed back to immobilize the preassembled winding 17 in an axial direction.
• the teeth 1 1 are arranged uniformly on the cylinder head 10 as visible in FIG. 2.
• the cylinder head 10 is circular and has a recess in its center dimensioned to accommodate the rotor 4.
• stator 3a In operation, the magnetic field generated by the turns of tooth 1 1 of stator 3a crosses the air gaps ENT and the rotor 4 in its discoid part and penetrates into the stator tooth arranged opposite on stator 3b.
• the magnetic field is guided by the breech of the stator 3b to an adjacent tooth then crosses again the air gaps ENT and the rotor 4 in its discoid part, and enters a stator tooth placed opposite on the stator 3a to go towards a adjacent stator tooth via the stator cylinder head 3 a.
• the needles 15 of the stator teeth 1 1 are oriented in the direction of travel of the magnetic field, and the sheet of yokes 10 is wound in the direction of travel of the magnetic field.
• the magnetic flux loopback is optimized, thus reducing the magnetic losses of machine 1 and improving the efficiency of machine 1.
• FIG. 4 illustrates a partial view of tooth 1 1 comprising the needles 15 housed in the envelope 12 and a tongue 16.
• the conductive material comprises thin sheets 23 stacked inside the envelope 12 in the radial direction.
• the thickness of the thin sheet 23 extends in the radial direction, the width of the thin sheet extends between the first 13 and second 14 faces and the length of the sheet extends in a direction orthogonal to the radial direction .
• the thin sheet 23 has for example a rectangular section.
• the stack of thin sheets 23 is for example in a direction parallel to the side of length different from that of the other two sides of the isosceles triangle.
• the thin sheets 23 are joined together for example by surface weld beads before their insertion into the envelope 12. After insertion of the thin sheets 23 into the envelope 12, the interstices between the thin sheets and the envelope are filled with glue for example a resin.
• the thickness of the thin sheets is preferably less than 0.35mm, for example equal to 0.2mm. The choice of this thickness depends on the frequency of use of the rotary machine 1.
• FIG. 6 illustrates a third embodiment of the tooth 1 1 fixed on the cylinder head 10.
• This tooth 11 includes a stud and tongues 16.
• the stud is in one piece, the conductive material being produced by compacting a ferrous powder coated with electrical insulator.
• the stud further comprises lateral extensions 24 extending on either side of the axis of symmetry (B) towards the outside of the stud and comprising at each of their ends recesses 25.
• the lateral extensions 24 create a isthmus increasing the torque developed by the rotating electric machine 1.
• Clips 26 and 27 of elastic steel fixed to the cylinder head 10 are housed in the recesses 25 so as to hold the stud against the cylinder head 10.
• the flaps 22 trap the staples 26 and 27 and hold the preassembled winding 17 (not shown) on the peripheral surface of the casing 12, by welding on the yoke of their end. More specifically, the flaps 22, by means of the staples bearing on the stud in the recesses 25, ensure the plating, with a certain pressure, of the stud against the cylinder head 10. The flaps hold the studs and the coils in this third embodiment.
• the steel grains of the ferrous powder are magnetically oriented in the axial direction.
• the fine segmentation of the stator teeth 1 1 mounted on the cylinder head 10 makes it possible to combat losses by eddy currents.
• stator yoke may be segmented to facilitate the assembly of the teeth and the stator windings.

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Iron Core Of Rotating Electric Machines (AREA)

Applications Claiming Priority (2)

Publications (1)

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Citations (2)

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• 2018
  • 2018-10-16 FR FR1859559A patent/FR3087304B1/fr active Active
• 2019
  • 2019-09-23 WO PCT/EP2019/075556 patent/WO2020078667A1/fr not_active Ceased
  • 2019-09-23 CN CN201980066519.0A patent/CN112823467B/zh active Active
  • 2019-09-23 EP EP19795457.1A patent/EP3868008A1/de active Pending

Patent Citations (2)

Non-Patent Citations (1)

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