Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02K—DYNAMO-ELECTRIC MACHINES
  • H02K23/00—DC commutator motors or generators having mechanical commutator; Universal AC/DC commutator motors
  • H02K23/02—DC commutator motors or generators having mechanical commutator; Universal AC/DC commutator motors characterised by arrangement for exciting
  • H02K23/04—DC commutator motors or generators having mechanical commutator; Universal AC/DC commutator motors characterised by arrangement for exciting having permanent magnet excitation
• • 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
  • H02K1/17—Stator cores with permanent magnets

Definitions

• Rotating electrical machine in particular motor vehicle starter
• the present invention relates to a rotary electrical machine, in particular a starter motor vehicle.
• EP-B1 -985 334 discloses a starter comprising a stator provided with a plurality of magnetic poles disposed on an inner circumferential surface of a cylinder head. Each magnetic pole is formed by a permanent ferrite magnet magnetized so that the north and south poles appear radially. Auxiliary magnets may be provided between the aforementioned magnets. These auxiliary magnets are made of ferrite and magnetized so that the north and south poles appear circumferentially. Space is provided between each auxiliary magnet and the cylinder head. Such an arrangement can reduce magnetic leakage.
• a strong magnetic reaction of armature in a DC brushed electric machine in particular in a starter having a magneto-motor force (fmm) of great intensity at very low voltage and in power greater than 1 kW, can cause a decrease in performance of the machine.
• an angular offset of the brushes and / or a compensating winding or switching aid are used to overcome the adverse effects related to the armature magnetic reaction.
• the angular offset of the brushes is optimal only for an electric current of predetermined intensity.
• the aforementioned compensation winding is generally bulky.
• the invention aims in particular to provide an improved rotating electrical machine, particularly more efficient.
• the subject of the invention is thus a rotating electric machine with direct current, in particular for a starter of a motor vehicle, the machine comprising:
• stator comprising a magnetized structure with permanent magnetization, this magnetized structure extending along a circumference of the stator and being arranged to generate a magnetic induction field
• a rotor which, during the operation of the machine, produces, in an air gap, also called an 'air-gap' in English, between the magnetized structure and the rotor, a magnetic armature reaction,
• the magnetized structure comprises at least one sector of a first type having a magnetization vector making with a radial direction an angle which varies when one moves on a circumference of the magnetized structure, the magnetization in this sector taking at least locally a different direction of radial and orthoradial directions of the stator, the magnetic induction field in the gap associated with this sector of the magnetized structure and the rotor rotor magnetic reaction having normal components of opposite signs, the magnetic induction field generated by this sector of the magnetized structure being chosen to at least attenuate or cancel, locally, an adverse effect of the armature magnetic reaction, and
• the magnetized structure comprises at least one sector of a second type having a magnetization vector making with the radial direction of the stator a substantially constant angle when moving on a circumference of the magnetic structure, the magnetic induction field in the gap associated with this sector of the magnetized structure and the magnetic armature reaction having normal components of the same sign.
• the stator in particular the magnetized structure, is advantageously devoid of a piece of soft magnetic material permeable to a magnetic field, and used for the derivation of a magnetic flux and the flux concentration (also called shunt piece).
• the magnetic structure according to the invention preferably comprises magnets of hard magnetic material non-permeable to a magnetic field. Thanks to the invention, the magnetic induction field generated by the magnetized structure of the stator, unladen without taking into account other existing fields in the air gap such as the magnetic armature reaction, has a profile providing a contribution of induction (by magnetic flux concentration) at the places where the effects of the armature magnetic reaction are opposed to those of the magnetic structure (the respective normal components with opposite signs).
• the resulting magnetic field profile optimizes the magnetic torque of the machine, and therefore its performance.
• the angle between the magnetization vector in the first type sector of the magnetized structure and the radial direction of the stator varies stepwise when moving over a circumference of the magnetic structure.
• this sector of the first type comprises a succession of permanent magnets each having a direction of uniform magnetization.
• the angle between the magnetization vector in the first-type sector of the magnetized structure and the radial direction of the stator varies substantially continuously as one moves about a circumference of the magnetized structure.
• the magnetization vector in the first type sector of the magnetized structure varies from an orthoradial to a radial direction when moving on a circumference of the magnetized structure between two ends of this sector.
• the transition of the magnetization direction can correspond to 90 °.
• the magnetized structure may comprise two sectors of the first type, alternating with two sectors of the second type, the angular extent of one of the sectors of the first type being in particular greater than that of the one of the second type of sectors.
• a machine with two pairs of poles may have four sectors of each type.
• the number of sectors of each type thus depends on the number of poles of the machine.
• the first type sector of the magnetized structure may extend over an angle greater than 60 ° or 90 °, being in particular substantially equal to 120 °.
• the magnetization vector has a substantially radial direction.
• the magnetized structure comprises two sectors of the second type, each of these sectors extending over a lower angle 90 °, being notably substantially equal. at 60 °.
• the magnetized structure comprising sectors of the first and second types extends over the entire circumference of the stator, in particular in a continuous manner.
• the magnetized or magnetic structure comprises at least one angular break in the magnetization angle, between the first type sector and the second type sector, this angular break corresponding in particular to a change in the angle of magnetization between 45 ° and 135 °, being in particular substantially equal to 90 °.
• the angular break in the direction of magnetization passing from the first sector to the second corresponds for example to a tilting of the magnetization direction from radial to orthoradial.
• the magnetized structure and in particular its magnetization vector, has an asymmetry between a first set comprising a first sector of the first type and a first sector of the second type, and a second set comprising a second sector of the first type and a second sector. second sector of the second type.
• the magnetic field resulting from the magnetic induction field generated by the magnetized structure and the armature magnetic rotor reaction comprises a normal component having, along a major part of the first type sector, a non-zero slope of sign constant.
• the maximum amplitude of the normal component of the magnetic induction field associated with the first type sector is greater than this maximum amplitude associated with the second type sector of the magnetized structure.
• the angular offset between an armature axis and an inductor axis is chosen in order to reduce the effects of the displacement of the magnetic neutral line under load.
• This neutral line can be defined as the place where the resulting induction vanishes between two consecutive poles of the inductor.
• said angular offset (mechanical angle) is for example between 10 ° and 20 °, being in particular between 13.5 ° and 19.5 °.
• the angular offset is for example 16.5 °.
• the neutral line may optionally be offset relative to the poles depending on the intensity of the load of the machine, for example to facilitate the switching aid by shifting brushes.
• At least one of the magnetization sectors of the magnetized structure comprises a plurality of permanent magnets placed side by side, in particular against a cylinder head of the machine.
• the electric machine according to the invention can be arranged to operate at a maximum power of between 500 W and 2000 W, for example.
• FIG. 1 shows, schematically and partially, a motor vehicle starter according to an exemplary implementation of the invention
• FIG. 2 represents, schematically and partially, a magnetized structure equipping the starter of FIG. 1, and
• FIGS. 3 and 4 show schematically the variation of the normal component of different magnetic fields in the air gap of the machine of FIG. 1,
• FIG. 5 represents, schematically and partially, a magnetized structure according to a state of the art
• FIGS. 6 and 7 diagrammatically show the variation of the normal component of different magnetic fields associated with the magnetized structure of FIG.
• FIG. 1 shows very schematically a starter 1 for a motor vehicle combustion engine.
• This DC starter 1 comprises, firstly, a rotor 2, also called armature, rotatable about an axis X, and secondly, a stator 3, also called inductor.
• This stator 3 comprises a yoke 4 carrying a magnetized structure 5 with permanent magnetization.
• the rotor 2 comprises a rotor body 7 and a winding 8 wound in notches of the rotor body 7.
• the rotating electrical machine formed by the starter 1 is of the type of a pair of poles.
• the winding 8 forms, on either side of the rotor body 7, a front bun 9 and a rear bun 10.
• the rotor 2 is provided, at the rear, with a collector 12 comprising a plurality of contact pieces electrically connected to the conductive elements, formed in the example in question by wires, of the winding 8.
• a group of brushes 13 and 14 is provided for the power supply of the winding 8, one of the brushes 13 being connected to the ground of the starter 1 and another of the brushes 14 being connected to an electrical terminal 15 of a switch 17 via a wire 16.
• the brushes are for example four in number.
• the brushes 13 and 14 rub against the collector 12 when the rotor 2 is rotating, allowing the rotor 2 to be powered by switching the electric current in sections of the rotor 2.
• the starter 1 further comprises a launcher assembly 19 slidably mounted on a drive shaft 18 and drivable in rotation about the X axis by the rotor 2.
• a gear reduction unit 20 is interposed between the rotor 2 and the drive shaft 18, in a manner known per se.
• the starter 1 may be of the 'Direct Drive' type, without a gearbox.
• the launcher assembly 19 comprises a drive element formed by a pinion 21 and intended to engage on a drive member of the combustion engine, not shown.
• This drive member is for example a ring gear.
• the launcher assembly 19 further comprises a freewheel 22 and a pulley washer 23 defining between them a groove 24 for receiving the end 25 of a fork 27.
• This fork 27 is made for example by molding a plastic material.
• the fork 27 is actuated by the switch 17 to move the launcher assembly 19 relative to the drive shaft 18, along the X axis, between a first position in which the launcher assembly 19 drives the combustion engine by intermediate pinion 21, and a second position in which the launcher assembly 19 is disengaged from the combustion engine.
• the switch 17 comprises, in addition to the terminal 15 connected to the brush 14, a terminal 29 connected via an electrical connection element, in particular a wire 30, to a power supply of the vehicle, in particular a battery.
• FIG. 2 shows a magnetized structure 5 according to an exemplary implementation of the invention, intended to equip the starter 1.
• the magnetized structure 5 comprises a number of permanent magnets 40 equal to 24. These permanent magnets 40 are arranged continuously over the entire circumference of the stator 3.
• the magnetized structure 5 of the stator comprises:
• Each of sectors 41 and 42 includes eight permanent magnets, and each of sectors 43 and 44 includes four permanent magnets. Alternatively, sectors 41 to 44 may each be formed by a single permanent magnet.
• the direction of magnetization varies, when one moves circumferentially on one of the magnetization sectors 41 and 42 from one circumferential end to the other, from a radial direction to an orthoradial direction.
• the 90 ° transition of the magnetization direction along the sector 41 takes place between a direction of orthoradial magnetization and a direction of radial magnetization directed towards the inner circumference of the stator, while that that along the sector 42 is carried out between a direction of orthoradial magnetization and a direction of radial magnetization directed towards the outer circumference of the stator.
• the variation of the direction of magnetization in the sectors 41 and 42 occurs in stages due to the use of several permanent magnets 40 of uniform magnetization within them.
• the variation of the direction of the magnetization in each sector 41 and 42 is substantially continuous.
• Magnet sectors 41 to 44 are alternated, namely sector 41, respectively 42, is disposed between sectors 43 and 44, creating a break in the direction of magnetization when passing from sector 44 to sector 41 or sector 43 to sector 42, counter-clockwise.
• the angular break corresponds, in the example described, to a tilting of the magnetization direction from radial F1 to orthoradial F2. This break is thus thus
• the magnetized structure formed by a first set comprising the sectors 41 and 43 and a second set comprising the sectors 42 and 44, and in particular the magnetization vector of this structure has an asymmetry.
• each sector 41 or 42 extends over an angle greater than or equal to 90 °.
• each sector 41; 42 extends over 120 °
• each sector 43; 44 extends over 60 °.
• the magnetic structure 5 may have a higher number of pairs of poles, for example four or eight.
• the angular offset between an armature axis A2 and an inductor axis A1 is chosen in order to reduce the effects of the displacement of the neutral line.
• This angular offset is for example between 0 and 60 ° for a machine with a pair of poles.
• the graphs of FIGS. 3 and 4 illustrate the variation, as a function of the angle, of the normal component of the fields, namely Bn.no-load (vacuum induction generated by the magnetized structure), Bn.arm.reac (induction related to the armature reaction) and Bn. resuit (resulting induction of Bn.no-load and Bn.arm.reac), for the magnetized structure 5 of FIG. 2.
• the magnetic field resulting from the magnetic induction field generated by the magnetized structure and the magnetic armature reaction of the rotor comprises a normal component Bn. resuit having, along a major part of the sector 41 or 42 of the first type, a non-zero slope of constant sign, as can be seen in the graph of FIG. 4.
• the maximum amplitude of the normal component Bn.No-load of the magnetic induction field associated with the sector 41 or 42 of the first type is greater than this maximum amplitude associated with the sector 43 or 44 of the second type of the magnetic structure.
• the magnetic induction field Bn.No-load generated by the sectors 41 and 42 of the magnetized structure compensates locally for an adverse effect of the armature magnetic reaction Bn.arm .reac.
• the magnetic induction field Bn.no-Load generated by the magnetized structure of the stator, unladen without taking into account other existing fields in the air gap such as the magnetic armature reaction has a profile providing a induction contribution (by concentration of magnetic flux) at the places where the effects of the armature magnetic reaction Bn.Arm.reac are opposed to those of the magnetic structure (the respective normal components Bn.no-Load and Bn. Arm.reac with opposite signs), especially around the 0 ° and 180 ° angles.
• the first sectors 41 and 42 where the magnetized structure has a magnetization vector allowing a magnetic energy concentration so as to increase the level thereof provide for the case to empty a previous excess or, in other words, an induction supply, in anticipation of the load case, where the harmful effect of the magnetic reaction of armature consists in particular in reducing the level of useful induction which comes from the inductor permanent magnet.
• the magnetized structure according to the invention makes it possible to counter-balance the demagnetizing effect of the armature reaction, at the places where it penalizes the performance of the rotating electrical machine, ie under the halves of inductive poles. corresponding, without doing any action under the halves of poles where the armature reaction is magnetising in the same direction as the contribution of the inductor. Thanks to the invention, which consists in particular in adding vacuum induction before a retrenchment during operation in charge of the machine, one obtains an operation with a satisfactory resultant induction profile.
• FIG. 5 shows a magnetized structure 50 according to a state of the art.
• This structure 50 comprises two sectors 51 and 52 forming two poles and each having a uniform direction magnetization, namely of radial direction.
• the graphs of FIGS. 6 and 7 show that at the places where the effects of the magnetic reaction of armature Bn.Arm.reac oppose those of the magnetic structure Bn.no-Load, there is a lack of contribution of significant induction on the part of the magnetized structure 50.
• the Bn field. resuit has an induction deficit.

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Permanent Field Magnets Of Synchronous Machinery (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=40428294

Family Applications (1)

Country Status (4)

Citations (4)

Family Cites Families (1)

• 2008
  • 2008-06-13 FR FR0853923A patent/FR2932619B1/fr not_active Expired - Fee Related
• 2009
  • 2009-06-08 EP EP09761926A patent/EP2286504A2/de not_active Withdrawn
  • 2009-06-08 CN CN200980122133.3A patent/CN102067419B/zh not_active Expired - Fee Related
  • 2009-06-08 WO PCT/FR2009/051079 patent/WO2009150375A2/fr not_active Ceased

Patent Citations (4)

Non-Patent Citations (2)

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