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WO2018103969A1 - Permanent magnet synchronous electric motor - Google Patents

Permanent magnet synchronous electric motor Download PDF

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Publication number
WO2018103969A1
WO2018103969A1 PCT/EP2017/077942 EP2017077942W WO2018103969A1 WO 2018103969 A1 WO2018103969 A1 WO 2018103969A1 EP 2017077942 W EP2017077942 W EP 2017077942W WO 2018103969 A1 WO2018103969 A1 WO 2018103969A1
Authority
WO
WIPO (PCT)
Prior art keywords
rotor
magnets
magnet
electric motor
coupling holes
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.)
Ceased
Application number
PCT/EP2017/077942
Other languages
French (fr)
Inventor
Burcu DURAK
Merve Ayca TELEMEZ
Caglar ACAR
Hakan Gedik
Ipek DOKUMCU
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.)
Arcelik AS
Original Assignee
Arcelik AS
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 Arcelik AS filed Critical Arcelik AS
Priority to EP17792075.8A priority Critical patent/EP3552302A1/en
Publication of WO2018103969A1 publication Critical patent/WO2018103969A1/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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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
    • H02K1/274—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets
    • H02K1/2753—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets the rotor consisting of magnets or groups of magnets arranged with alternating polarity
    • H02K1/276—Magnets embedded in the magnetic core, e.g. interior permanent magnets [IPM]
    • 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
    • H02K21/46—Motors having additional short-circuited winding for starting as an asynchronous motor

Definitions

  • the present invention relates to an electric motor wherein permanent magnets are disposed in the rotor.
  • electric motors that have the asynchronous motor feature at the start-up and the synchronous motor feature in continuous operation are used.
  • This type of electric motor is known as permanent magnet synchronous motors.
  • permanent magnets that are embedded in the rotor are used in addition to the aluminum magnetic cage (squirrel cage) structure in the rotor slots.
  • the electric motor starts up asynchronously by means of the magnetic cage disposed in the rotor and operates synchronously after the start-up by means of the permanent magnets disposed in the rotor.
  • the magnets are disposed in the rotor after the aluminum injection process in order to solve this problem.
  • the magnets need to be fixed against the risk of breaking away their coupling holes, before causing magnetic flux irregularities and any harm to the rotor balance after being placed in the rotor.
  • the aim of the present invention is the realization of a permanent magnet synchronous electric motor that has an easy-to-produce low-cost rotor, with improved start-up and operation efficiency.
  • an external circlip that prevents the magnets from dislodging from the coupling holes thereof is attached to a circlip channel (adjacent to the rotor package) that is disposed on the rotor shaft and that is disposed right in front of a annular surface of the rotor package composed of laminations.
  • the external circlip comprises magnet retaining extensions that extend outwards in the radial direction from the side thereof, that partially cover the magnet coupling holes and that prevent the magnets from dislodging from the coupling holes thereof by bearing against the magnets.
  • Figure 1 – is the schematic view of an electric motor.
  • Figure 2 - is the exploded view of a rotor, magnets to be attached to the rotor, and an external circlip having magnet retaining extensions.
  • Figure 3 - is the perspective view of an external circlip comprising magnet retaining extensions.
  • Figure 4 - is the front schematic view of the rotor, wherein the external circlip having the magnet retaining extensions is attached.
  • Figure 5 - is the perspective view of the rotor, wherein the external circlip having the magnet retaining extensions is attached.
  • Figure 6 - is the front schematic view of the rotor, wherein the external circlip having the magnet retaining extensions extending in the radial direction is attached in an embodiment of the present invention.
  • the electric motor (1) comprises a stator (2); a cylindrical rotor (3) that is composed of stacked magnetic steel laminations and that has annular and planar front and rear surfaces; a shaft (5) that is snap-fitted into the shaft hole (4) arranged at the center of the rotor (3); a plurality of magnet coupling holes (7) that are disposed around the shaft hole (4), that extend towards the interior of the rotor (3) in the axial direction from the annular surface of the rotor (3) and wherein magnets (6) providing synchronous operation are disposed; and a plurality of slots (11) that extend in the rotor (3) all around and in the axial direction in the area close to the cylindrical side surface of the rotor (3) and wherein aluminum is injected in the injection mold during the production of the rotor (3).
  • the electric motor (1) of the present invention comprises
  • an external circlip (10) that extends on the annular rotor (3) surface, that bears against the magnets (6) by at least partially covering the magnet coupling holes (7) and that has at least one magnet retaining extension (9) that prevents the magnets (6) from dislodging from the magnet coupling holes (7) by preventing the movement of the magnets (6) in the axial direction.
  • the magnet retaining extensions (9) are produced as a single piece with the external circlip (10) from the spring steel and extend outwards in the radial direction from the side of the external circlip (10).
  • the laminations whereon the shaft hole (4), the slots (11), and the magnet coupling holes (7) are disposed are fixed by being stacked and then placed into the aluminum injection mold, and aluminum is injected into the slots (11) from an annular surface of the core of the rotor (3).
  • the aluminum material is prevented from entering the magnet coupling holes (7) and the shaft hole (4) by means of various methods while aluminum is being injected into the core of the rotor (3).
  • the magnets (6) are disposed into the magnet coupling holes (7) after the aluminum injection process, and thus the magnets (6) are prevented from being affected from high temperature.
  • the external circlip (10) is attached to the circlip channel (8) arranged in the shaft (5) that is previously attached to the rotor (3).
  • the magnet retaining extensions (9) integrated with the external circlip (10) extend on the annular surface of the rotor (3) so as to at least partially cover the magnet coupling holes (7), and bear against the magnets (6) so as to prevent the same from dislodging.
  • the external circlip (10) comprises at least one T-shaped magnet retaining extension (9) that bears against the magnets (6) with the arms that constitute the T-shape.
  • the electric motor (1) comprises four magnet coupling holes (7) with rectangular cross-sections that are arranged around the shaft hole (4) and four magnets (6) with rectangular cross-sections that are disposed into the magnet coupling holes (7), and the external circlip (10) comprises two T-shaped magnet retaining extensions (9), each bearing against two magnets (6).
  • the electric motor (1) comprises four magnet coupling holes (7) with rectangular cross-sections that are arranged around the shaft hole (4) and four magnets (6) with rectangular cross-sections that are disposed into the magnet coupling holes (7), and the external circlip (10) comprises four bar-shaped magnet retaining extensions (9) that extend outwards in the radial direction, each bearing against at least one magnet (6).
  • the magnets (6) that are disposed by being embedded to the rotor (3) are prevented from dislodging from the magnet coupling holes (7) during the operation of the electric motor (1) at high rotational speeds.
  • An external circlip (10) that is produced from spring steel and around which magnet retaining extensions (9) are added is used in order to keep the magnets (6) in the magnet coupling holes (7).
  • the external circlip (10) is easily mounted by using circlip pliers, and material and labor savings in the production of the electric motor (1) are provided.

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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)

Abstract

The present invention relates to a permanent magnet synchronous electric motor (1) comprising a stator (2); a cylindrical rotor (3) that is composed of stacked magnetic steel laminations and that has annular and planar front and rear surfaces; a shaft (5) that is snap-fitted into the shaft hole (4) arranged at the center of the rotor (3); a plurality of magnet coupling holes (7) that are disposed around the shaft hole (4), that extend towards the interior of the rotor (3) in the axial direction from the annular surface of the rotor (3) and wherein magnets (6) providing synchronous operation are disposed; and a plurality of slots (11) that extend in the rotor (3) all around and in the axial direction in the area close to the cylindrical side surface of the rotor (3) and wherein aluminum is injected in the injection mold during the production of the rotor (3).

Description

PERMANENT MAGNET SYNCHRONOUS ELECTRIC MOTOR
The present invention relates to an electric motor wherein permanent magnets are disposed in the rotor. Especially in industrial embodiments where high start-up moment and high operation efficiency are important, electric motors that have the asynchronous motor feature at the start-up and the synchronous motor feature in continuous operation are used. This type of electric motor is known as permanent magnet synchronous motors. In the electric motor, permanent magnets that are embedded in the rotor are used in addition to the aluminum magnetic cage (squirrel cage) structure in the rotor slots. The electric motor starts up asynchronously by means of the magnetic cage disposed in the rotor and operates synchronously after the start-up by means of the permanent magnets disposed in the rotor. Reaching high temperatures while the aluminum material is being injected into the rotor slots and the magnets embedded in the rotor losing their magnetic features due to high temperature create problems in the production of this type of rotor. The magnets are disposed in the rotor after the aluminum injection process in order to solve this problem. Especially in the high speed electric motors, the magnets need to be fixed against the risk of breaking away their coupling holes, before causing magnetic flux irregularities and any harm to the rotor balance after being placed in the rotor.
The International Patent Applications No. WO2008012269 (A1), WO2008012270 (A1), and WO2008012271 (A1) relate to a permanent magnet synchronous electric motor where the magnets that are disposed in the rotor by being embedded are prevented from dislodging.
The aim of the present invention is the realization of a permanent magnet synchronous electric motor that has an easy-to-produce low-cost rotor, with improved start-up and operation efficiency.
In the electric motor realized in order to attain the aim of the present invention, an external circlip that prevents the magnets from dislodging from the coupling holes thereof is attached to a circlip channel (adjacent to the rotor package) that is disposed on the rotor shaft and that is disposed right in front of a annular surface of the rotor package composed of laminations. The external circlip comprises magnet retaining extensions that extend outwards in the radial direction from the side thereof, that partially cover the magnet coupling holes and that prevent the magnets from dislodging from the coupling holes thereof by bearing against the magnets.
Figure 1 – is the schematic view of an electric motor.
Figure 2 - is the exploded view of a rotor, magnets to be attached to the rotor, and an external circlip having magnet retaining extensions.
Figure 3 - is the perspective view of an external circlip comprising magnet retaining extensions.
Figure 4 - is the front schematic view of the rotor, wherein the external circlip having the magnet retaining extensions is attached.
Figure 5 - is the perspective view of the rotor, wherein the external circlip having the magnet retaining extensions is attached.
Figure 6 - is the front schematic view of the rotor, wherein the external circlip having the magnet retaining extensions extending in the radial direction is attached in an embodiment of the present invention.
The elements in the figures are numbered as follows:
  1. Electric motor
  2. Stator
  3. Rotor
  4. Shaft hole
  5. Shaft
  6. Magnet
  7. Magnet coupling hole
  8. Circlip channel
  9. Retaining extension
  10. External circlip
  11. Slot
The electric motor (1) comprises a stator (2); a cylindrical rotor (3) that is composed of stacked magnetic steel laminations and that has annular and planar front and rear surfaces; a shaft (5) that is snap-fitted into the shaft hole (4) arranged at the center of the rotor (3); a plurality of magnet coupling holes (7) that are disposed around the shaft hole (4), that extend towards the interior of the rotor (3) in the axial direction from the annular surface of the rotor (3) and wherein magnets (6) providing synchronous operation are disposed; and a plurality of slots (11) that extend in the rotor (3) all around and in the axial direction in the area close to the cylindrical side surface of the rotor (3) and wherein aluminum is injected in the injection mold during the production of the rotor (3).
The electric motor (1) of the present invention comprises
- a circlip channel (8) that is bored on the shaft (5) and that is adjacent to the annular rotor (3) surface where the magnets (6) are disposed into the magnet coupling holes (7), and
- an external circlip (10) that extends on the annular rotor (3) surface, that bears against the magnets (6) by at least partially covering the magnet coupling holes (7) and that has at least one magnet retaining extension (9) that prevents the magnets (6) from dislodging from the magnet coupling holes (7) by preventing the movement of the magnets (6) in the axial direction.
The magnet retaining extensions (9) are produced as a single piece with the external circlip (10) from the spring steel and extend outwards in the radial direction from the side of the external circlip (10).
While the rotor is being produced (3), the laminations whereon the shaft hole (4), the slots (11), and the magnet coupling holes (7) are disposed are fixed by being stacked and then placed into the aluminum injection mold, and aluminum is injected into the slots (11) from an annular surface of the core of the rotor (3). The aluminum material is prevented from entering the magnet coupling holes (7) and the shaft hole (4) by means of various methods while aluminum is being injected into the core of the rotor (3). The magnets (6) are disposed into the magnet coupling holes (7) after the aluminum injection process, and thus the magnets (6) are prevented from being affected from high temperature. After the magnets (6) are disposed, by using circlip pliers the external circlip (10) is attached to the circlip channel (8) arranged in the shaft (5) that is previously attached to the rotor (3). The magnet retaining extensions (9) integrated with the external circlip (10) extend on the annular surface of the rotor (3) so as to at least partially cover the magnet coupling holes (7), and bear against the magnets (6) so as to prevent the same from dislodging.
In an embodiment of the present invention, the external circlip (10) comprises at least one T-shaped magnet retaining extension (9) that bears against the magnets (6) with the arms that constitute the T-shape.
In this embodiment, the electric motor (1) comprises four magnet coupling holes (7) with rectangular cross-sections that are arranged around the shaft hole (4) and four magnets (6) with rectangular cross-sections that are disposed into the magnet coupling holes (7), and the external circlip (10) comprises two T-shaped magnet retaining extensions (9), each bearing against two magnets (6).
In another embodiment of the present invention, the electric motor (1) comprises four magnet coupling holes (7) with rectangular cross-sections that are arranged around the shaft hole (4) and four magnets (6) with rectangular cross-sections that are disposed into the magnet coupling holes (7), and the external circlip (10) comprises four bar-shaped magnet retaining extensions (9) that extend outwards in the radial direction, each bearing against at least one magnet (6).
In the embodiment of the present invention, the magnets (6) that are disposed by being embedded to the rotor (3) are prevented from dislodging from the magnet coupling holes (7) during the operation of the electric motor (1) at high rotational speeds. An external circlip (10) that is produced from spring steel and around which magnet retaining extensions (9) are added is used in order to keep the magnets (6) in the magnet coupling holes (7). The external circlip (10) is easily mounted by using circlip pliers, and material and labor savings in the production of the electric motor (1) are provided.

Claims (6)

  1. An electric motor (1) comprising a stator (2); a rotor (3); a shaft (5) that is snap-fitted into a shaft hole (4) arranged at the center of the rotor (3), and a plurality of magnet coupling holes (7) that are arranged around the shaft hole (4), that extend towards the interior of the rotor (3) in the axial direction from the annular surface of the rotor (3) and wherein magnets (6) are disposed; characterized by
    - a circlip channel (8) that is bored on the shaft (5) and that is adjacent to the annular rotor (3) surface where the magnets (6) are disposed into the magnet coupling holes (7), and
    - an external circlip (10) that arranged on the circlip channel (8) and extends on the annular rotor (3) surface, that bears against the magnets (6) by at least partially covering the magnet coupling holes (7) and that has at least one magnet retaining extension (9) that prevents the magnets (6) from dislodging from the magnet coupling holes (7).
  2. An electric motor (1) as in Claim 1, characterized by the magnet retaining extensions (9) that are produced as a single piece with the external circlip (10) from spring steel.
  3. An electric motor (1) as in Claim 1 or 2, characterized by at least one T-shaped magnet retaining extension (9) that bears against the magnets (6) with the arms that constitute the T-shape.
  4. An electric motor (1) as in Claim 3, characterized by four magnet coupling holes (7) with rectangular cross-sections that are arranged around the shaft hole (4), four magnets (6) with rectangular cross-sections that are disposed into the magnet coupling holes (7), and two T-shaped magnet retaining extensions (9), each bearing against two magnets (6).
  5. An electric motor (1) as in Claim 1 or 2, characterized by the magnet retaining extensions (9) that extend outwards in the radial direction from the side of the outer external circlip (10).
  6. An electric motor (1) as in Claim 5, characterized by four magnet coupling holes (7) with rectangular cross-sections that are arranged around the shaft hole (4), four magnets (6) with rectangular cross-sections that are disposed into the magnet coupling holes (7); and four bar-shaped magnet retaining extensions (9) that extend outwards in the radial direction, each bearing against at least one magnet (6).
PCT/EP2017/077942 2016-12-08 2017-11-01 Permanent magnet synchronous electric motor Ceased WO2018103969A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP17792075.8A EP3552302A1 (en) 2016-12-08 2017-11-01 Permanent magnet synchronous electric motor

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
TR2016/18100A TR201618100A2 (en) 2016-12-08 2016-12-08 SYNCHRONOUS ELECTRIC MOTOR WITH CONTINUOUS MAGNET
TRA2016/18100 2016-12-08

Publications (1)

Publication Number Publication Date
WO2018103969A1 true WO2018103969A1 (en) 2018-06-14

Family

ID=60201593

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2017/077942 Ceased WO2018103969A1 (en) 2016-12-08 2017-11-01 Permanent magnet synchronous electric motor

Country Status (3)

Country Link
EP (1) EP3552302A1 (en)
TR (1) TR201618100A2 (en)
WO (1) WO2018103969A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11742710B2 (en) 2018-11-29 2023-08-29 Milwaukee Electric Tool Corporation Rotor assembly for an electric motor

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4525925A (en) * 1983-09-22 1985-07-02 General Electric Company Method of making permanent magnet rotor
US4639627A (en) * 1983-04-20 1987-01-27 Fanuc Ltd. Interlocking yoke and endplates for permanent magnet rotor
JP2005130688A (en) * 2003-10-01 2005-05-19 Asmo Co Ltd Magnets-embedded rotor and electric motor
WO2008012269A1 (en) 2006-07-25 2008-01-31 Arcelik Anonim Sirketi An electric motor
WO2008012270A1 (en) 2006-07-25 2008-01-31 Arcelik Anonim Sirketi Line start permanent magnet electric motor
WO2008012271A1 (en) 2006-07-25 2008-01-31 Arcelik Anonim Sirketi An electric motor
US20090108694A1 (en) * 2007-10-31 2009-04-30 Aisan Kogyo Kabushiki Kaisha Rotor and pump
US20090315423A1 (en) * 2008-06-18 2009-12-24 Honda Motor Co., Ltd. Motor
EP2560268A2 (en) * 2011-08-19 2013-02-20 Kabushiki Kaisha Yaskawa Denki Rotor of rotating electric machine, rotating electric machine, and end face member of rotor
US20130093279A1 (en) * 2011-10-14 2013-04-18 Mitsubishi Electric Corporation Rotor of rotary electric machine

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4639627A (en) * 1983-04-20 1987-01-27 Fanuc Ltd. Interlocking yoke and endplates for permanent magnet rotor
US4525925A (en) * 1983-09-22 1985-07-02 General Electric Company Method of making permanent magnet rotor
JP2005130688A (en) * 2003-10-01 2005-05-19 Asmo Co Ltd Magnets-embedded rotor and electric motor
WO2008012269A1 (en) 2006-07-25 2008-01-31 Arcelik Anonim Sirketi An electric motor
WO2008012270A1 (en) 2006-07-25 2008-01-31 Arcelik Anonim Sirketi Line start permanent magnet electric motor
WO2008012271A1 (en) 2006-07-25 2008-01-31 Arcelik Anonim Sirketi An electric motor
US20090108694A1 (en) * 2007-10-31 2009-04-30 Aisan Kogyo Kabushiki Kaisha Rotor and pump
US20090315423A1 (en) * 2008-06-18 2009-12-24 Honda Motor Co., Ltd. Motor
EP2560268A2 (en) * 2011-08-19 2013-02-20 Kabushiki Kaisha Yaskawa Denki Rotor of rotating electric machine, rotating electric machine, and end face member of rotor
US20130093279A1 (en) * 2011-10-14 2013-04-18 Mitsubishi Electric Corporation Rotor of rotary electric machine

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11742710B2 (en) 2018-11-29 2023-08-29 Milwaukee Electric Tool Corporation Rotor assembly for an electric motor
US12401243B2 (en) 2018-11-29 2025-08-26 Milwaukee Electric Tool Corporation Rotor assembly for an electric motor

Also Published As

Publication number Publication date
TR201618100A2 (en) 2018-06-21
EP3552302A1 (en) 2019-10-16

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