NL1037352C2 - Rotor assembly and electromotor with permanent magnets having reduced eddy current losses. - Google Patents

Rotor assembly and electromotor with permanent magnets having reduced eddy current losses. Download PDF

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Publication number
NL1037352C2
NL1037352C2 NL1037352A NL1037352A NL1037352C2 NL 1037352 C2 NL1037352 C2 NL 1037352C2 NL 1037352 A NL1037352 A NL 1037352A NL 1037352 A NL1037352 A NL 1037352A NL 1037352 C2 NL1037352 C2 NL 1037352C2
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NL
Netherlands
Prior art keywords
rotor assembly
stator
rotor
plastic
electromotor
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Application number
NL1037352A
Other languages
Dutch (nl)
Inventor
Dave Nicolaas Clarenbach
Johan Jacob Wolmarans
Hendrik Polinder
Original Assignee
Aeronamic B V
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 Aeronamic B V filed Critical Aeronamic B V
Priority to NL1037352A priority Critical patent/NL1037352C2/en
Application granted granted Critical
Publication of NL1037352C2 publication Critical patent/NL1037352C2/en

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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
    • H02K1/278—Surface mounted magnets; Inset magnets
    • 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

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

Description

Title: Rotor assembly and electromotor with permanent magnets having reduced eddy current losses.
DESCRIPTION
5 The present invention relates to a rotor assembly and an electromotor with permanent magnets having reduced eddy current losses. More in particular, the invention relates to a rotor assembly and electromotor with permanent magnets for high speed applications.
The use of electromotors having a stator and a rotor with permanent 10 magnets as part of the rotor assembly is widespread, especially in the field of synchronous motors and other applications where rotor excitation supply frequency as a function of circumferential speed is required. Hard permanent magnets may be used, with various compositions, including compositions with rare earth metals. In electromotors with rotor assemblies having such permanent magnets, time and 15 space harmonics induced in the rotor assembly by the stator via an air gap between the stator and rotor give rise to eddy currents in the rotor contributing to thermal losses in the electromotor.
Time harmonics are caused by higher order harmonics in currents used to excite the stator, whereas space harmonics are caused by higher harmonics 20 due to spatial discontinuities in stator architecture such as discrete concentrated windings around stator teeth. At higher rotor speeds the thermal losses due to eddy currents tend to increase. Electromotors at high circumferential speeds may require specially adapted cooling systems to dissipate the heat losses from the motor. Such cooling systems may require a cooling liquid to be circulated through the 25 electromotor thereby increasing risk of failure, complexity, weight and system losses.
To overcome increasing eddy current losses, rotor assembly designs have been introduced with segmented magnets grouped around a rotor body which may be manufactured from fibre reinforced material. An example of such 30 a design is disclosed in German patent publication no. DE 4105352 A1. In this motor the rotor is formed from compressed metal powder including weak magnetic, highly permeable metal particles surrounded by an electrically isolating layer. The magnets are mounted on the circumference of the rotor.
At higher, a circumferential rotor speeds however, the discrete 1037352 2 magnet elements have a tendency to disbond from the rotor assembly under circumferential loads. In addition, due to the higher eddy current losses at higher speeds, the permanent magnet elements heat up, which reduces their magnetic flux. It is therefore an object of the invention to provide a rotor assembly of an 5 electromotor for high circumferential speeds having reduced eddy current losses, hence less heat losses, and which is capable of running at high circumferential speed without disbonding of the permanent magnets and allowing the use of air cooling.
The object is achieved in a rotor assembly, as part of an 10 electromotor, where the rotor assembly comprises a rotor body, a cylindrical permanent magnet element arranged around the rotor body, whereby the magnet element comprises at least one rotor pole pair, wherein at least one rotor pole pair is formed by means of a pair of radially opposite magnetized areas, a sleeve arranged around the cylindrical permanent magnet element, the sleeve formed by fibre 15 reinforced synthetic material. The cylindrical permanent magnet element is formed by means of a plastic bonded magnet. The plastic bonded magnet may have radially magnetized areas to result in the at least one pole pair. The plastic bonded magnet may also be formed by circumferentially separate sections, each section magnetized in different radial directions as to provide for the at last one magnetic pole pair, the 20 sections of the plastic bonded magnet being grouped around and fixed to the rotor body and being held together by the sleeve.
Plastic bonded magnets are primarily known for domestic use or low performance equipment where magnetic parts may be manufactured by means of injection moulding or compression bonding. Plastic bonded magnets provide form 25 freedom, only limited by the manufacturing method, while achieving moderate magnetic properties. The use of a plastic bonded magnet in a high performance electromotor is however advantageous since it provides low conductivity and hence low eddy currents at high circumferential speeds.
Plastic bonded magnets would normally not be considered 30 favourable for high speed electromotor applications due to their limited mechanical strength, but by mechanically supporting the plastic bonded magnet by means of the sleeve, radial pre-stress is provided to the plastic bonded magnet, thereby fixing the plastic bonded magnet to the rotor body and preventing disbonding of the plastic bonded magnet at high circumferential speeds.
3
Because of the low heat losses due to the low eddy-currents and the high mechanical strength the rotor assembly according to the invention is fit for use in high performance electromotors at high circumferential speeds which are air 5 cooled, thereby allowing for compact designs previously not feasible in the art.
In an embodiment according to the invention, the plastic bonded magnet comprises hard magnetic particles in a binder of synthetic material. Hard magnetic particles have the advantage that they are resistant to de-magnetization in a strong magnetic field in opposite direction. The binder provides insulation between 10 the magnetic particles to provide low conductivity and hence low eddy currents.
In an embodiment of the invention the sleeve is constructed from carbon fibre reinforced plastics. Carbon fibre reinforced plastics are electrically low conductive materials and are therefore not prone to heating from eddy current development and thus will not have a significant contribution to heat losses in the 15 electromotor.
In an embodiment according to the invention the plastic bonded magnet comprises hard magnetic particles such as neodymium iron-boron or samarium cobalt particles and a thermal plastic polymer binder such as Polyphenylenesulfide (PPS). The volume fraction of the hard magnetic particles is 20 more preferably at least 80% in order to maintain magnetic properties suitable for use in the rotor assembly.
In another embodiment according to the invention the plastic bonded magnet is segmented into stacked plastic bonded magnet rings arranged around the rotor body. This provides a further reduction of eddy currents by breaking 25 up and thereby shortening the eddy current path in the plastic bonded magnet in the longitudinal direction of the rotor body.
In a further embodiment according to the invention the plastic bonded magnet rings have a thickness in a range of 0,1 to 10 mm. In yet a further preferred embodiment the thickness of the plastic bonded magnet rings is 3 mm.
30 In another embodiment of the invention the rotor body is at least in part constructed from an electrically conducting metal such as iron, whereby the rotor body is surrounded by a shielding layer. The shielding layer counteracts eddy currents to be induced in the metal part of the rotor body by preventing that magnetic fields reach the metal rotor body part or parts.
4
The shielding layer may be constructed from thin metal rings. The rings may for example have a thickness of 0,1 mm.
In an alternative embodiment of the invention the rotor body is constructed from carbon fiber reinforced plastics. The rotor body of carbon fiber 5 reinforced plastics is low conductive, so the rotor body itself will not be prone to eddy currents and does not contribute to heat losses in the electric motor.
The problem is also solved according to another aspect of the invention in an electromotor, comprising a stator arranged in a stator housing, whereby the stator is provided with at least one pair of stator teeth, and wherein 10 each pair of stator teeth has been provided with stator windings for electromagnetically exciting the teeth. The electromotor further comprises a rotor assembly as described above, whereby the rotor assembly has been arranged within the stator along a common central axis such that the rotor assembly is free to rotate around the central axis and whereby the rotor assembly is suspended such that the 15 at least one pair of rotor poles magnetically interact via an air gap with the at least one pair of stator pole shoes causing a rotating movement of the rotor assembly with respect to the stator when in use the stator windings are electrically excited.
The invention will be further explained in the following detailed description and accompanying figures, wherein: 20 figure 1 shows a longitudinal cross section of a rotor assembly according to an exemplary embodiment of the invention; figure 2 shows a longitudinal cross section of an electromotor having a rotor assembly according to an exemplary embodiment of the invention; figure 3 shows a cross section of the electromotor of figure 2 along 25 the line A-A'.
Figure 1 shows a longitudinal cross section of a rotor assembly 101 for use in an electromotor comprising a rotor body 102 having flanges 103a, 103b.
Surrounding the rotor body 102 a plastic bonded magnet 106 is arranged having a common central axis 107. The plastic bonded magnet 106 is 30 preferably of cylindrical shape and is radially magnetized to create at least one magnetic pole pair. The plastic bonded magnet may also be circumferentially subdivided into sections extending radially and axially or longitudinally grouped around the rotor body, having different radial magnetization to create magnetic poles.
5
The plastic bonded magnet 106 may be segmented into plastic bonded magnet rings 106a, 106b to counteract eddy currents induced in use in an electromotor by the varying magnetic fields from outside of the rotor assembly 101. Practical ring thicknesses may be in the range of 0,1 10 mm, however optimal 5 results in terms of eddy current losses versus mechanical strength may be obtained . with a thickness of around 3 mm.
The rotor body 102 may be constructed from various materials known in the art, from metal, such as iron or steel, and/or from synthetic materials or composite materials such as fiber reinforced plastics. If the rotor body is 10 manufactured from metal, it requires a shielding layer 104 as is shown in figure 1 to shield the metal rotor body from varying magnet fields induced in use in an electromotor from outside of the rotor assembly 101. The shielding layer 104 may be manufactured from segmented metal rings reducing eddy currents induced in the shielding layer 104. The plastic bonded magnet 106 is fitted on top of and 15 surrounding the shielding layer 104.
Surrounding the plastic bonded magnet 106 a sleeve 105 is provided. The rotor body 102 may be arranged such that the plastic bonded magnet 106 can be fitted onto the rotor body 102 during manufacturing. For example at least one of the flanges 103a, 103b may be fixed to the rotor body 102 after fitting the 20 plastic bonded magnet 106.
The sleeve 105 is preferably constructed from a composite material such as carbon fibre reinforced plastic comprising of the carbon fibers embedded in a thermoset or thermoplast resin. The sleeve 105 provides radial prestress on the plastic bonded magnet 106, the shielding layer 104 if present and the rotor body 25 102. Thus the sleeve 105 prevents the plastic bonded magnet 106 from disbonding from the rotor body 102 and/or shielding layer 104. The carbon fibers in the sleeve 105 provide low conductivity, so the sleeve 105 contributes to a low extent to eddy-current losses in the rotor assembly 101 and therefore to heat losses in the electromotor.
30 The plastic bonded magnet 106 preferably comprises hard magnetic particles such as magnetized neodymium iron-boron or samarium-cobalt particles in a binder of synthetic material. Other rare earth magnetic materials may apply. Bonded magnets manufactured by injection moulding typically have magnetic particle volume fractions in the order of 60% or lower. For compression bonding this 6 can be higher, up to 85% - 90%. However the volume fraction of the hard magnetic particles is more preferably at least 80%. This way the magnetic properties of the plastic bonded magnet approach those of solid hard magnets.
The binder of synthetic material can be a thermal plastic material 5 such as Polyphenylene Sulfide (PPS) or Polyamide (PA).
Figure 2 shows a longitudinal cross section of an exemplary electromotor 201 having a rotor assembly 101 as described above. The electromotor 201 further comprises a stator 203 contained in a stator housing 202. The rotor assembly 101 is suspended between bearings 204a, 204b making it rotatable around central axis 107. The 10 bearings 204a, 204b may for example be fitted onto the stator housing 202 in support structures 206a, 206b.
The stator 203 is arranged around the rotor assembly 101 such that an air gap 205 is created between the stator 203 and the rotor assembly 101. The stator 203 is provided with pole shoes (not shown in figure 2) having coils or 15 electrical windings (also not shown) which act as a electromagnet when an electric current passes through them. The windings are wound around the pole shoes having a core of preferably a magnetic steel-like material which transfers the magnetic flux produced by the windings.
Thus an alternating current through the coils provided by an 20 electrical AC power supply connected to the windings results in magnetic interaction between the stator 203 and the rotor assembly 101 via the air gap 205 enabling the rotor assembly 101 to be driven in a rotary motion around the central axis 107.
It is the varying magnetic field from the stator 203, caused by the alternating currents in the windings around the pole shoes of the stator 203, having 25 components perpendicular to conductive parts of the rotor assembly 101, and the relative motion of the rotor assembly 101 to the stator 203 that cause eddy currents in those conducting parts and therefore contribute to heat losses in the electromotor.
Figure 3 shows a cross section of the electromotor of figure 2 along the lines A A'. The electromotor comprises a combination of a stator 203 in a stator 30 housing 202 and a rotor assembly 101 as described in relation to figures 1 and 2 respectively. The stator 203 is shown in more detail having a plurality of electromagnetically excitable pole shoes around the inner side of the stator 203. In figure 3 only two pole shoes are provided with reference numerals 301a, 301b to improve readability of figure 3. Electrical windings (not shown) for excitation of the 7 stator 203 may be placed around the pole shoes 301a, 301b and may be arranged in the stator winding slots 303 which are located in the stator 203 in longitudinal direction adjacent to the pole shoes 301a, 301b. The electrical windings around pole shoes 301a, 301b are separated by means of spacers 304, so in the example of 5 figure 3 6 pole shoes are shown, separated by 6 spacers.
The rotor assembly 101 is shown in figure 3 with a plastic bonded magnet 106 being circumferentially subdivided in sections which are magnetized in different radial directions. Sections having radially opposite directions in and out of the plastic bonded magnet form a rotor pole pair 302a, 302b. Thus figure 3 10 illustrates a four pole pair magnet arrangement of the plastic bonded magnet 106. More specifically the four pole pair is shown in a Halbach arrangement, providing optimal magnetic strength at the pole pair section having a radially inward or outward oriented magnetic field.
The rotor assembly 101 and stator 203 are radially separated by air 15 gap 205 allowing the stator 203 and rotor assembly 101 to interact magnetically. By appropriate excitation of the electrical windings around the pole shoes 301a, 301b of the stator 203 a rotating magnetic field may be created within the airgap 205 between the stator 203 and the rotor assembly 101, as is well known in the art. In the example of figure 3, when all windings around the 6 pole shoes 301a, 301b are 20 connected to a six phase AC power source a rotating magnetic field may be generated having four rotating pole pairs This rotating magnetic field interacts with the magnetic field generated by the permanent magnet of the rotor assembly 101 causing the rotor assembly 101 to rotate.
The embodiments as described are intended as exemplary 25 embodiments only and are not intended to limit the scope of the invention as laid down in the following claims. A skilled person may vary, change, modify or add features to these embodiments without departing from the inventive concept of the invention.
30 8
Verwijzingscijfers / Reference numerals Rotorsamenstel Rotor assembly 101
Rotorlichaam Rotor body 102 5 Flenzen Flanges 103a, 103b
Afschermlaag Shielding layer 104
Bandage Sleeve 105
Plastic gebonden magnet Plastic bonded magnet . 106
Magneetringen Magnetic rings 106a, 106b 10 Symmetrie-as Symmetry axis 107
Rotor aseinden Rotor axis ends 108a, 108b
Elektromotor Electromotor 201
Statorhuis Stator housing 202
Stator Stator 203 15 Lagers Bearings 204a, 204b
Luchtspleet Air gap 205
Lagerhuis Bearing support structures 206a, 206b
Statortand Statortooth 301a, 301b
Rotorpoolpaar Rotor pole pair 302a, 302b 20 Sleuf voor statorwikkeling Stator winding slot 303
Stator afstandshouder Stator spacer 304 1037352

Claims (10)

1. Rotorsamenstel (101) voor een elektromotor, het rotorsamenstel (101) omvattende: 5 een rotorlichaam (102); een cilindrisch permanent magneetelement (106) aangebracht om het rotorlichaam (102), waarbij het magneetelement (106) ten minste een rotorpoolpaar (302a, 302b) omvat, en waarbij het rotorpoolpaar (302a, 302b) gevormd wordt door een paar in radiale richting gemagnetiseerde gebieden; 10 een bandage (105) aangebracht om het cilindrisch permanent magneetelement (106), waarbij de bandage (105) gevormd is uit een met koolstof-vezels versterkte kunststof, met het kenmerk, dat het cilindrisch permanent magneetelement (106) wordt gevormd 15 door een plastic gebonden magneet (PBM).A rotor assembly (101) for an electric motor, the rotor assembly (101) comprising: a rotor body (102); a cylindrical permanent magnet element (106) disposed around the rotor body (102), the magnet element (106) comprising at least one rotor pole pair (302a, 302b), and wherein the rotor pole pair (302a, 302b) is formed by a pair of radially magnetized areas; 10 a bandage (105) arranged around the cylindrical permanent magnet element (106), the bandage (105) being formed from a carbon-fiber reinforced plastic, characterized in that the cylindrical permanent magnet element (106) is formed by a plastic bonded magnet (PPE). 2. Rotorsamenstel (101) volgens conclusie 1, waarbij de plastic gebonden magneet samengesteld is uit hardmagnetische deeltjes in een bindmiddel uit kunststofmateriaal.The rotor assembly (101) of claim 1, wherein the plastic bonded magnet is composed of hard magnetic particles in a binder of plastic material. 3. Rotorsamenstel (101) volgens conclusie 2, waarbij de hardmag-20 netische deeltjes neodymium ijzer-borium-deeltjes of samarium-cobalt-deeltjes zijn met een volumepercentage van ten minste 80% en het bindmiddel een thermoplastische polymeer is, zoals polyfenylsulfide (PPS).3. Rotor assembly (101) according to claim 2, wherein the hard-magnetic particles are neodymium iron-boron particles or samarium-cobalt particles with a volume percentage of at least 80% and the binder is a thermoplastic polymer such as polyphenyl sulfide (PPS) ). 4. Rotorsamenstel (101) volgens een van de voorgaande conclusies, waarbij het magneetelement (106) in de lengterichting van het rotorlichaam (102) is 25 opgebouwd uit op elkaar gestapelde PBM ringen (106a, 106b).4. Rotor assembly (101) as claimed in any of the foregoing claims, wherein the magnet element (106) is constructed in the longitudinal direction of the rotor body (102) from PBM rings (106a, 106b) stacked on top of each other. 5. Rotorsamenstel (101) volgens conclusie 4, waarbij de ringdikte van de PBM ringen (106a, 106b) in het bereik van 0,1 tot en met 10 mm ligt.The rotor assembly (101) of claim 4, wherein the ring thickness of the PBM rings (106a, 106b) is in the range of 0.1 to 10 mm. 6. Rotorsamenstel (101) volgens conclusie 5, waarbij de ringdikte van de PBM ringen (106a, 106b) 3 mm bedraagt.The rotor assembly (101) of claim 5, wherein the ring thickness of the PBM rings (106a, 106b) is 3 mm. 7. Rotorsamenstel (101) volgens een van voorgaande conclusies, waarbij het rotorlichaam (102) ten minste ten dele is opgebouwd uit een metaal, zoals ijzer, en is afgeschermd voor een wisselend magnetisch veld door een afschermlaag (104) aangebracht tussen het rotorlichaam (102) en het magneet element (106). 1037352The rotor assembly (101) according to any of the preceding claims, wherein the rotor body (102) is at least partially constructed from a metal, such as iron, and is shielded from an alternating magnetic field by a shielding layer (104) disposed between the rotor body ( 102) and the magnet element (106). 1037352 8. Rotorsamenstel (101) volgens een van voorgaande conclusies, waarbij het rotorlichaam (102) is opgebouwd een uit een met koolstofvezels versterkte kunststof.Rotor assembly (101) according to one of the preceding claims, wherein the rotor body (102) is made up of a plastic fiber-reinforced plastic. 9. Rotorsamenstel (101) volgens een van de voorgaande conclusies, waarbij de bandage (105) opgebouwd is uit een met koolstofvezels versterkte kunststof.Rotor assembly (101) according to one of the preceding claims, wherein the bandage (105) is made of a plastic fiber-reinforced plastic. 10. Elektromotor (201), omvattende: een stator (203) aangebracht in een statorhuis (202), 10 waarbij de stator (203) is voorzien van ten minste twee statortanden (301a, 301b); en waarbij elke statortand (301a, 301b) is voorzien vaneen statorwikkeling voor het elektromagnetisch bekrachtigen van de statortanden (301a, 301b); 15 een rotorsamenstel (101) volgens een van de voorgaande conclusies, waarbij het rotorsamenstel (101) is aangebracht binnen de stator (203) langs een gemeenschappelijke centrale symmetrie as (107), waarbij het rotorsamenstel (101) draaibaar is aangebracht in het statorhuis en waarbij het rotorsamenstel (101) zodanig is opgehangen dat het ten minste een rotorpoolpaar 20 (302a, 302b) via een luchtspleet (205) een zodanige magnetische wisselwerking heeft met de ten minste twee statortanden (301a, 301b) door elektrische bekrachtiging van de statorwikkelingen, dat een draaibeweging van het rotorsamenstel (101) ten opzichte van de stator (203) wordt bewerkstelligd. 25 30 1037352An electric motor (201), comprising: a stator (203) mounted in a stator housing (202), the stator (203) having at least two stator teeth (301a, 301b); and wherein each stator tooth (301a, 301b) is provided with a stator winding for electromagnetically energizing the stator teeth (301a, 301b); A rotor assembly (101) according to any of the preceding claims, wherein the rotor assembly (101) is disposed within the stator (203) along a common central symmetry axis (107), the rotor assembly (101) being rotatably mounted in the stator housing and the rotor assembly (101) being suspended such that the at least one rotor pole pair (302a, 302b) has such an magnetic interaction with the at least two stator teeth (301a, 301b) via an air gap (205a, 301b) by electrically energizing the stator windings, that a rotational movement of the rotor assembly (101) relative to the stator (203) is effected. 25 30 1037352
NL1037352A 2009-10-05 2009-10-05 Rotor assembly and electromotor with permanent magnets having reduced eddy current losses. NL1037352C2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
NL1037352A NL1037352C2 (en) 2009-10-05 2009-10-05 Rotor assembly and electromotor with permanent magnets having reduced eddy current losses.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NL1037352A NL1037352C2 (en) 2009-10-05 2009-10-05 Rotor assembly and electromotor with permanent magnets having reduced eddy current losses.
NL1037352 2009-10-05

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Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3021396A1 (en) * 1980-06-06 1981-12-17 Philips Patentverwaltung Gmbh, 2000 Hamburg Permanent magnet rotor for electrical machines - esp. for bicycle dynamo, where reinforced polymer shaft is moulded into barium ferrite ring magnet
JPS58133153A (en) * 1982-02-01 1983-08-08 Seikosha Co Ltd Rotor of motor
EP0308647A1 (en) * 1987-08-26 1989-03-29 Siemens Aktiengesellschaft Manufacturing method for an anchor between a rotating shaft and an overmoulded rotating part
JPH03190541A (en) * 1989-12-19 1991-08-20 Kawasaki Steel Corp Plastic magnet rotor and manufacture thereof
EP0854558A2 (en) * 1997-01-21 1998-07-22 Isuzu Ceramics Research Institute Co., Ltd. Structure of a rotor for generators and method of manufacturing the same rotor
JPH1189143A (en) * 1997-09-11 1999-03-30 Hitachi Ltd Permanent magnet type rotor
EP1333558A2 (en) * 2002-01-31 2003-08-06 Hitachi, Ltd. Rotor for rotating electric machine and method of fabricating the same, for gas turbine power plant
US6765319B1 (en) * 2003-04-11 2004-07-20 Visteon Global Technologies, Inc. Plastic molded magnet for a rotor
EP1722457A2 (en) * 2005-05-10 2006-11-15 Hitachi, Ltd. Motor

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3021396A1 (en) * 1980-06-06 1981-12-17 Philips Patentverwaltung Gmbh, 2000 Hamburg Permanent magnet rotor for electrical machines - esp. for bicycle dynamo, where reinforced polymer shaft is moulded into barium ferrite ring magnet
JPS58133153A (en) * 1982-02-01 1983-08-08 Seikosha Co Ltd Rotor of motor
EP0308647A1 (en) * 1987-08-26 1989-03-29 Siemens Aktiengesellschaft Manufacturing method for an anchor between a rotating shaft and an overmoulded rotating part
JPH03190541A (en) * 1989-12-19 1991-08-20 Kawasaki Steel Corp Plastic magnet rotor and manufacture thereof
EP0854558A2 (en) * 1997-01-21 1998-07-22 Isuzu Ceramics Research Institute Co., Ltd. Structure of a rotor for generators and method of manufacturing the same rotor
JPH1189143A (en) * 1997-09-11 1999-03-30 Hitachi Ltd Permanent magnet type rotor
EP1333558A2 (en) * 2002-01-31 2003-08-06 Hitachi, Ltd. Rotor for rotating electric machine and method of fabricating the same, for gas turbine power plant
US6765319B1 (en) * 2003-04-11 2004-07-20 Visteon Global Technologies, Inc. Plastic molded magnet for a rotor
EP1722457A2 (en) * 2005-05-10 2006-11-15 Hitachi, Ltd. Motor

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