EP3607639A1 - Rotor d'un moteur à courant continu sans balais, en particulier d'un moteur électrique à rotor interne, et moteur électrique doté d'un tel rotor - Google Patents

Rotor d'un moteur à courant continu sans balais, en particulier d'un moteur électrique à rotor interne, et moteur électrique doté d'un tel rotor

Info

Publication number
EP3607639A1
EP3607639A1 EP18708117.9A EP18708117A EP3607639A1 EP 3607639 A1 EP3607639 A1 EP 3607639A1 EP 18708117 A EP18708117 A EP 18708117A EP 3607639 A1 EP3607639 A1 EP 3607639A1
Authority
EP
European Patent Office
Prior art keywords
rotor
electric motor
ring magnet
stator
ring
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP18708117.9A
Other languages
German (de)
English (en)
Inventor
Patrick Budaker
Joachim Heizmann
Michael PALSULE DESAI
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Robert Bosch GmbH
Original Assignee
Robert Bosch GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Robert Bosch GmbH filed Critical Robert Bosch GmbH
Publication of EP3607639A1 publication Critical patent/EP3607639A1/fr
Pending legal-status Critical Current

Links

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
    • H02K1/2726—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of a single magnet or two or more axially juxtaposed single magnets
    • H02K1/2733—Annular magnets
    • 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
    • H02K21/14—Synchronous motors having permanent magnets; Synchronous generators having permanent magnets with stationary armatures and rotating magnets with magnets rotating within the armatures
    • H02K21/16—Synchronous motors having permanent magnets; Synchronous generators having permanent magnets with stationary armatures and rotating magnets with magnets rotating within the armatures having annular armature cores with salient poles
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K29/00—Motors or generators having non-mechanical commutating devices, e.g. discharge tubes or semiconductor devices
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K7/00—Arrangements for handling mechanical energy structurally associated with dynamo-electric machines, e.g. structural association with mechanical driving motors or auxiliary dynamo-electric machines
    • H02K7/14—Structural association with mechanical loads, e.g. with hand-held machine tools or fans
    • H02K7/145—Hand-held machine tool
    • 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
    • H02K2213/00—Specific aspects, not otherwise provided for and not covered by codes H02K2201/00 - H02K2211/00
    • H02K2213/03—Machines characterised by numerical values, ranges, mathematical expressions or similar information

Definitions

  • Rotor for a brushless DC motor in particular for an internal rotor electric motor, and electric motor with such a rotor
  • the invention relates to a rotor for an electric motor, in particular for an internal rotor electric motor. Furthermore, the invention relates to an electric motor with a rotor according to the invention.
  • An electric motor is an energy converter that converts electrical energy into mechanical energy.
  • Such an electric motor includes a stator that forms the stationary motor part and a rotor that forms the moving motor part.
  • the annular or cylindrical rotor generally encloses the motor shaft on which it is also fastened, and in turn is enclosed by the stator which is spaced apart from the rotor in the radial direction.
  • the stator is usually provided with a stator yoke, on which radially to the center, inwardly projecting stator teeth are arranged, whose rotor-facing ends form the so-called pole piece.
  • the associated stator of the motor coils must be interconnected in a certain way. The way this interconnection is defined by applied to the stator teeth windings, which generate a magnetic field in the electromotive operation.
  • the stator material is usually metallic, for example soft magnetic iron.
  • the winding scheme may for example describe a star connection of the coils or a delta connection of the coils. Belongs to the stator a plurality of coils to be interconnected with each other, then the interconnection is very expensive, since the respective coils are to be connected by individual wires in a certain way with each other.
  • a disadvantage of the design of the rotor with ring magnets is that the ring magnets are mechanically less robust due to their manufacturing process and can not absorb the centrifugal forces occurring at large rotor radii and / or high rotational speeds without damage. As a result, the motor powers of electric motors with such rotors are generally comparatively low.
  • the object of the invention is to improve the above-mentioned disadvantages and to provide a rotor for an electric motor, which at the same time has a comparatively high magnetic flux and a low leakage flux, but at the same time is suitable for high rotational speeds. Furthermore, the invention has the object to further develop an electric motor and a hand tool according to.
  • the invention comprises a rotor for a brushless DC motor having a shaft, a rotor core arranged on the shaft, wherein the rotor core serves as a return body, and a ring magnet attached to the rotor core and surrounding the rotor core.
  • the ring magnet is designed in the form of an annular disk, wherein a radial direction and a circumferential direction are defined by the annular disk shape.
  • the winding of the rotor is connected in delta connection.
  • the delta connection proves to be advantageous in the production, since they usually smaller wire diameter required in brushless DC motor with small turns and large wire diameters (eg in battery-powered hand tool) than the star connection, the delta connection is advantageous in the production.
  • Adapting the form of the source voltage to the current form results in higher machine utilization and a more uniform torque curve.
  • the ring magnet has a radial anisotropic grain structure.
  • ring magnets deliver a higher overall magnetic flux due to the larger pole width and the lower leakage flux.
  • the magnetic remanence flux density can be increased, which in turn reduces the active axial length of the motor and / or the electrical resistance and the power density of the electric motor can be increased in comparison.
  • the ring magnet is preferably a multi-pole magnetized NdFeB ring magnet on the outer circumference.
  • the ring magnet has at least three pole pairs, preferably at least 8 pole pairs, more preferably at least 18 pole pairs.
  • the ring magnet is a sintered rare earth magnet of SmCo powder, a sintered ferrite magnet of NdFeB powder, a hot-pressed / hot-formed magnet, or a bonded magnet, wherein the radially anisotropic grain structure is produced by a two-stage compaction method.
  • the radially oriented anisotropic injection molded ring magnets are usually manufactured by electromagnetic orientation technology. Unlike simple permanent magnet orientation, magnets made by electromagnetic orientation are demagnetized before sinking, and then polarized according to the desired requirements.
  • the ring magnet By producing the ring magnet by hot pressing the NdFeB powder, an increased mechanical strength or robustness of the ring magnet can be ensured.
  • the radial anisotropy introduced in a separate production step of the grain structure of the ring magnet leads to a remanent flux density which is again increased by approximately 10% compared to conventionally sintered ring magnets and thus to an increased power density.
  • the production of the ring magnet can also be produced by another method, for example by the extrusion method.
  • the ring magnet is attached to the rotor core by one of the attachment methods from the group gluing, soldering, thermal shrinking, welding.
  • the geometry and topology of the stator can vary as the number of pole pairs of the ring magnet depending on the design.
  • An inventive radial anisotropic ring magnet is not subject to any restrictions in terms.
  • Another object of the present invention is an electric motor, preferably brushless internal rotor electric motor.
  • the electric motor comprises a stator and a rotor.
  • the stator has an annular disk-shaped stator yoke through which a radial direction and a circumferential direction are defined, as well as a defined number of pole teeth projecting radially inward from the stator yoke.
  • the rotor is enclosed by the stator in the radial direction. Between the stator and the rotor, a gap is arranged with a defined width.
  • the electric motor comprises a number of coils corresponding to the number of pole teeth, the coils being wound around the corresponding pole teeth. According to the invention, it is provided that the rotor according to one of the disclosed in the claims 1 to 12 and above embodiments is formed.
  • the electric motor has an idling speed of at least 24,000 revolutions per minute and a rotor diameter of the rotor of 30mm.
  • the coils of the electric motor are electrically connected in parallel.
  • a further subject of the present invention is a handheld power tool comprising an electric motor according to any one of claims 13 to 15.
  • FIG. 1 shows a detail of a rotor according to the invention and of an electric motor according to the invention
  • FIG. 2 shows an example of a delta connection with a parallel single-tooth winding
  • Fig. 4 is a schematic representation of a ring magnet with radially isotropic orientation of the magnetic preferred direction.
  • the rotor 10 of the electric motor 100 comprises inter alia a shaft 12, a rotor core 14 arranged on the shaft 12, wherein the rotor core 14 serves as a return body. Furthermore, the electric motor 100 comprises at least one ring magnet 16 fastened to the rotor core 14 and surrounding the rotor core 14.
  • the ring magnet 16 is of cylindrical ring shape, a radial direction and a circumferential direction being defined by the circular ring disk shape or cylinder ring shape.
  • the at least one ring magnet 16 is attached to the rotor core 14 by one of the attachment methods of the bonding, soldering, thermal shrinking, or welding group.
  • the electric motor 100 comprises a stator 20, wherein the stator 20 is an annular disc-shaped stator yoke 22, through which a radial direction and a circumferential direction is defined, and a defined number of from the stator yoke 22 to radially inwardly projecting pole teeth 24 has.
  • the pole teeth 24 are wound with a corresponding number of coils 30.
  • the ring magnet 16 has a radially anisotropic grain structure.
  • this radial anisotropy can be achieved in a compaction step following the first hot pressing, thus by a two-stage compaction process.
  • the ring magnet 16 may be a sintered ring magnet 16 of SmCo powder or NdFeB powder, wherein the radially anisotropic grain structure is also made by a two-stage compaction process.
  • the radially oriented anisotropic injection molded ring magnets 16 are typically manufactured by electromagnetic orientation technology. Unlike simple permanent magnet orientation, magnets made by electromagnetic orientation are demagnetized before sinking, and then polarized according to the desired requirements. In this way, for example, a ring magnet 16 shown in FIG. 4 can be produced with a radially isotropic orientation of the preferred magnetic direction.
  • the ring magnet 16 By producing the ring magnet 16 by hot pressing the NdFeB powder, an increased mechanical strength or robustness of the ring magnet can be ensured.
  • the radial anisotropy introduced in a separate production step of the grain structure of the ring magnet 16 leads to a remanent flux density which is again increased by approximately 10% compared to conventionally sintered ring magnets 16 and thus to an increased power density.
  • the production of the ring magnet 16 can also be produced by another method, for example by the extrusion method.
  • the anisotropy improves the magnetic remanence flux density up to 10% compared to conventional sintered NdFeB magnets and by a factor of 2.2 compared to the usual plastic-bonded NdFeB magnets.
  • This gain in magnetic flux across the ring magnet 16 can reduce the active axial length of the electric motor 100 and / or its electrical resistance. In accordance with the invention, this makes it possible to increase the power density of the electric motor 100 and at the same time its mechanical robustness. As a result, high speeds are possible even with large rotor diameters.
  • an electric motor 100 designed according to the invention can drive a rotational speed of more than 24000 rpm when idling at a rotor diameter of 30 mm.
  • Comparable values are currently provided in the prior art only with rotors with buried magnets, but with the above-mentioned disadvantages, which brings this construction with it.
  • the ring magnet 16 has at least three pole pairs, preferably at least 8 pole pairs, more preferably at least 18 pole pairs.
  • the number of pole pairs of the ring magnet varies depending on the design in terms of size and power of the electric motor, with a radially anisotropic ring magnet in this respect is subject to any restrictions.
  • the higher magnetic flux in a rotor according to the invention also requires larger cross sections in the stator geometry.
  • the number of poles is in principle not limited in the construction according to the invention, since a larger number of pole pairs reduces the cross section of the iron yoke. This is because the magnetic flux can divide to a higher number of pole pairs.
  • induced source voltage also called electromotive force or induced EMF voltage of the electric motor
  • the current waveform in the figure has a typical 120 ° block commutation
  • the induced source voltage is trapezoidal. This results in a high machine utilization and a largely uniform torque curve.
  • the trapezoidal shape of the source voltage achieves the largest possible machine utilization or largest power factor of the electric motor.
  • the induced source voltage is sinusoidal.
  • FIG. 4b shows a top view of the radially isotropic ring magnet 16 with an exemplary representation of the preferred magnetic direction.
  • 4a shows a corresponding sectional view.

Abstract

L'invention comprend un rotor d'un moteur à courant continu sans balais avec un arbre, un noyau de rotor disposé sur l'arbre, le noyau du rotor servant de corps de culasse, et un aimant annulaire fixé au noyau du rotor et entourant celui-ci. L'aimant annulaire est doté d'une forme circulaire qui définit une direction radiale et une direction circonférentielle. De plus, un nombre de trous q est défini par l'équation q=N/(2pm), où N représente le nombre de rainures dans le rotor, p représente un nombre de paires de pôles du rotor, et m représente un nombre de phases. Dans le cadre de cette invention, il est prévu que le circuit de l'enroulement du rotor soit en triangle.
EP18708117.9A 2017-04-07 2018-03-01 Rotor d'un moteur à courant continu sans balais, en particulier d'un moteur électrique à rotor interne, et moteur électrique doté d'un tel rotor Pending EP3607639A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE102017205950 2017-04-07
DE102018200077.8A DE102018200077A1 (de) 2017-04-07 2018-01-04 Rotor für einen bürstenlosen Gleichstrommotor, insbesondere für einen Innenläufer-Elektromotor, und Elektromotor mit einem solchen Rotor
PCT/EP2018/055019 WO2018184769A1 (fr) 2017-04-07 2018-03-01 Rotor d'un moteur à courant continu sans balais, en particulier d'un moteur électrique à rotor interne, et moteur électrique doté d'un tel rotor

Publications (1)

Publication Number Publication Date
EP3607639A1 true EP3607639A1 (fr) 2020-02-12

Family

ID=63588131

Family Applications (1)

Application Number Title Priority Date Filing Date
EP18708117.9A Pending EP3607639A1 (fr) 2017-04-07 2018-03-01 Rotor d'un moteur à courant continu sans balais, en particulier d'un moteur électrique à rotor interne, et moteur électrique doté d'un tel rotor

Country Status (6)

Country Link
US (1) US20210111601A1 (fr)
EP (1) EP3607639A1 (fr)
JP (1) JP2020513189A (fr)
CN (1) CN110720170A (fr)
DE (1) DE102018200077A1 (fr)
WO (1) WO2018184769A1 (fr)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3985848A1 (fr) * 2020-10-19 2022-04-20 Siemens Aktiengesellschaft Machine rotatoire dynamoélectrique
EP4037150A3 (fr) 2021-02-02 2022-09-14 Black & Decker, Inc. Moteur sans balai compact incluant des terminaux en ligne

Family Cites Families (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0591555A1 (fr) * 1992-04-28 1994-04-13 Sumitomo Special Metals Company Limited Aimants anisotropes cylindriques, leurs procedes de fabrication et moteurs les utilisant
JP3428002B2 (ja) * 1993-08-31 2003-07-22 大同特殊鋼株式会社 金属リング付き磁石ロータ及びその製造方法
US5682072A (en) * 1994-01-20 1997-10-28 Nsk Ltd. Three-phase brushless motor
JPH09233751A (ja) * 1996-02-27 1997-09-05 Fuji Electric Co Ltd 回転電機の磁石付回転子及びその製造方法
JP2003257762A (ja) * 2002-02-27 2003-09-12 Hitachi Ltd リング磁石とその製造法及び回転子と回転機並びにその磁界発生装置及びリング磁石製造装置
JP4244299B2 (ja) * 2003-03-12 2009-03-25 三菱電機株式会社 電動パワーステアリング装置用永久磁石型モータ
US6765319B1 (en) * 2003-04-11 2004-07-20 Visteon Global Technologies, Inc. Plastic molded magnet for a rotor
DE102004019636B4 (de) * 2004-04-22 2008-04-30 Minebea Co., Ltd. Bürstenloser Gleichstrommotor und Verfahren zum Justieren einer Sensorvorrichtung in einem bürstenlosen Gleichstrommotor
WO2009001801A1 (fr) * 2007-06-28 2008-12-31 Hitachi Metals, Ltd. Aimant annulaire anisotrope radial r-tm-b, son procédé de production, moule métallique pour sa production et rotor pour un moteur sans balai
JP2009017742A (ja) * 2007-07-09 2009-01-22 Daido Steel Co Ltd 磁石とその製造方法
JP5199704B2 (ja) * 2008-03-05 2013-05-15 株式会社ミツバ ブラシレスモータ
AT509030B1 (de) * 2008-10-08 2017-03-15 Minebea Co Ltd Verfahren zum starten und kommutieren eines bürstenlosen gleichstrommotors
JP5478987B2 (ja) * 2009-08-21 2014-04-23 株式会社マキタ 電動工具

Also Published As

Publication number Publication date
US20210111601A1 (en) 2021-04-15
DE102018200077A1 (de) 2018-10-11
WO2018184769A1 (fr) 2018-10-11
JP2020513189A (ja) 2020-04-30
CN110720170A (zh) 2020-01-21

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