AU675385B2 - Squirrel cage induction motor and rotor thereof - Google Patents
Squirrel cage induction motor and rotor thereof Download PDFInfo
- Publication number
- AU675385B2 AU675385B2 AU16569/95A AU1656995A AU675385B2 AU 675385 B2 AU675385 B2 AU 675385B2 AU 16569/95 A AU16569/95 A AU 16569/95A AU 1656995 A AU1656995 A AU 1656995A AU 675385 B2 AU675385 B2 AU 675385B2
- Authority
- AU
- Australia
- Prior art keywords
- plate part
- back plate
- rotor
- slot parts
- silicon steel
- 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
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/60—Other road transportation technologies with climate change mitigation effect
- Y02T10/64—Electric machine technologies in electromobility
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- Induction Machinery (AREA)
- Iron Core Of Rotating Electric Machines (AREA)
Description
AUSTRALIA
PATENTS ACT 1990 COMPLETE SPECIFICATION NAME OF APPLICANT(S): Hitachi, Ltd.
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ADDRESS FOR SERVICE: DAVIES COLLISON CAVE Patent Attorneys 1 Little Collins Street, Melbourne, 3000.
INVENTION TITLE: Squirrel cage induction motor and rotor thereof The following statement is a full description of of performing it known to me/us:this invention, including the best method PAOPOEKTAT\$0UJRRHtLS -8n%96 The present invention relates to a squirrel cage induction motor and a rotor of a squirrel cage induction motor and, particularly to an improvement of slot parts in a rotor iron core part constituting a part of a rotor.
Squirrel cage induction motors are used, in general, as motors for driving vehicles such as an electric car.
The rotor of a conventional squirrel cage induction motor is constituted as shown in Fig. 4. Rotor R' of the squirrel cage induction motor has a rotor iron core part 42 consisting of a silicon steel plate part 42a and two back plate parts 41.
In the silicon steel plate part 42a, silicon steel plates are stacked in the axial direction of the rotor The two back plate parts 41 are mounted respectively on each end of the silicon steel plate part 42a, and are held down by respective ones of two iron core retainers, at both ends of the back plate parts 41, and which exert a predetermined pressure against the plate part 42a.
Further, as shown in Fig. 4, slot parts 42b are formed in the rotor iron core part 42 at predetermined circunmferentially spaced intervals. Outer portions of the slot parts 42b, or 20 circumferential faces thereof, are open. Rotor conductors 43, are inserted respectively into ones of the slot parts 42b.
The back plate parts 41, constituting parts of the rotor iron core part 42, are so installed at both ends of the silicon steel plate part 42a as to transfer the pressure of the iron core 25 retainers to the whole silicon steel plate part 42a.
o0* Particularly, the iron core retainers for holding the rotor iron core part 42 from both ends exert pressure at the silicon steel plate part 42a under inner end portions of the slot parts 42b. These inner end portions are circumferentially arranged around the rotor iron core part 42, at predetermined intervals.
42, at predetermined intervals.
1';\OPlICAsqUIRR!LSPI O/I96 -3- However, by directly holding the silicon steel plate part 42a through the iron core retainers, the pressure of the iron core retainers is transferred to the silicon steel plate 42a under the inner end portions of the slot parts 42b of the rotor iron core part 42 but is not transferred to tooth portions, in particular to tip portions, of the rotor iron core part 42.
As a result, the back plate parts 41 are installed on both ends of the silicon steel plate part 42a so as to transfer the pressure of the iron core retainers to the whole silicon steel plate part 42a.
The outer portions of the slot parts 42b formed in the silicon steel plate part 42a are open, so as to reduce the leakage magnetic flux of the slot parts 42b. Generally, too, the back plate parts 41 also have respectively slot parts in which outer portions thereof are open in the same way as the silicon steel plate part 42a.
However, when the rotor R' of a squirrel cage induction motor having the above stated structure is used, the following facts have been ascertained.
Namely, since the back plate parts 41 comprising the slot parts in which the outer portions thereof are open are held on the silicon steel plate parts 42a under the inner end 20 portions of the slot parts by the iron core retainers, and further are in a cantilever state, only root portions of the tooth portions of the back plate parts 41 are fixed.
i The slot parts of the back plate parts 41 are larger in size than the slot parts 42b of the silicon steel plate part 42a, so that the tooth portions of the back plate parts 41 are thinner than 25 tooth portions of the silicon steel plate part 42a, and weaker in strength compared with that of the silicon steel plate parts 42a. Therefore, the intrinsic number of vibratiorn ig low.
As a result, it has been ascertained that the tooth portions of the back plate parts 41 are damaged in the vicinity of the root portions thereof due to the tensile and bending stresc ating 0 C in the radial direction or in the circumferential direction and arising for example because of by magnetic attraction and centrifugal forces which occur in operation.
P:\OPIJcATsQUIRRHLSPd &f109 -4- Further, since the natural or characteristic frequency is low, the pulsating torque generated when the motor is operated under inverter control, and resonance in the groove with a high harmonic wave is considered to cause damage.
Accordingly, in the conventional rotor R' of a squirrel cage induction motor, there is a problem that the squirrel cage induction motor is low in reliability.
Besides, as an improved rotor of the squirrel cage induction motor, Japanese utility model laid-open No. Sho 56-171,569 discloses a rotor comprising a rotor iron core part consisting of slot parts in which outer portions thereof are open and a rotor iron core consisting of slot parts in which outer portions thereof are closed one upon another alternately.
Further, Japanese patent laid-open No. Sho 55-29,291 describes a rotor consisting of slot parts in which outer portions thereof are open and closed, being alternately positioned at predetermined intervals circumferentially of a rotor iron core part.
However, in each of the above stated two conventional rotor, no consideration is given to the above stated problems.
20 Further, as disclosed in Japanese utility model publication No. Sho 33-6,740, a cast squirrel cage rotor having an air duct is known.
*o In this rotor, so as to prevent molten metal from flowing into an air duct through slot parts having open tops which are formed in a rotor iron core during the pouring operation, one 25 end of each the slot parts having open tops of the rotor iron core which faces toward the air *oo duct is covered with back plate parts have slot parts in which upper portions thereof are closed.
0 *00 However, in the above stated rotor, similarly to the above stated former two conventional prior art factors, no consideration is given to the above stated problems.
P:\OMPI3RXIN16S69-95.326 -2126 According to the present invention there is provided a rotor of a squirrel cage induction motor comprises: a rotor iron core part having a silicon steel plate part comprised of axially stacked silicon steel plates with back plate parts respectively arranged at each end of said silicon steel plate part; first slot parts formed in said silicon steel plate part at predetermined circumferential intervals around the rotor; and second slot parts formed in each said back plate part at predetermined circumferential intervals around the rotor and aligned with the first slot parts; wherein S 10 outer portions of said first slot parts are formed on said silicon steel plate part, said cuter portions of said first slot parts of said silicon steel plate part being open, and outer portions of said second slot parts are formed on said back plate part, and aligned with the outer portions of the first slot parts of the silicon steel plate part, at least one said back plate part being so formed that said outer portions of said second 15 slot parts of said at least one back plate part are closed.
The invention also provides a squirrel cage induction motor comprising a stator for generating a rotational magnetic field; and go a rotor arranged oppositely with said stator and having a rotor iron core part; and retainers for holding said rotor iron core part at both end sides thereof; 20 said rotor iron core part having a silicon steel plate part comprised of axially stacked silicon steel olates with back plate parts respectively arranged at each end of said silicon steel plate part; first slot parts formed in said silicon steel plate part at predetermined circumferential intervals around the rotor; and second slot parts formed in each said back plate part at predetermined circumferential intervals around the rotor and aligned with the first slot parts; wherein outer portions of said first slot parts are formed on said silicon steel plate part, said outer portions of said first plural slot parts of said silicon steel plate part being open, and outer portions of said second slot parts are formed on said back plate part, and aligned with the outer portions of the first slot part of the silicon steel plate part, at least one said back plate part being so formed that said outer portions of said second slot parts of said at least one back plate part being closed.
PAOIRWW\sQUIRRMLSV81-8/10 -6of sai beclk Platc part e-rece- Embodiments of the invention provide a high reliability squirrel cage induction motor and a rotor thereof wherein the strength of back plate parts can be ensured by suppressing an increase in the leakage magnetic flux of slot parts of the rotor iron core part.
By connecting to each other outer portions of the second plural slot parts formed on the back plate part, a ring is formed in the circumferential direction.
Accordingly, the supporting condition for the tooth portions of the back plate part can be changed from the cantilever state to the both-side fixed beam state.
Therefore, the rigidity of the tooth portions of the back plate part can be increased and the stress acting in the radial direction or in the circumferential direction by magnetic attraction and centrifugal force, that is, the tensile stress and the bending stress applied to the root portions of the tooth portions of the back plate parts, can be reduced.
The outer portions of the first slot parts are formed in the silicon steel plate part and the outer portions of the first slot parts of the silicon steel plate part may be open in the 20 conventional way, so that the leakage magnetic flux of the slot parts can be reduced.
a The invention is further described by way of example only with reference to the accompanying drawings in which:- 25 Fig. 1 is a fragmentary perspective view showing an end portion of one embodiment of a rotor of a squirrel cage induction motor according to the present invention; Fig. 2 is a fragmentary perspective view showing an end portion of another 5 embodiment of a rotor of a squirrel cage induction motor according to the present invention; Fig. 3 is a partial lengthwise cross-sectional view showing a rotor of a squirrel cage o induction motor taken a rotor according to the present invention; ana Fig. 4 is a fragmentary perspective view showing an end portion of a rotor of a I' MOPPOIIoAkXSQU!RRP-LSP -V1v6 conventional squirrel cage induction motor.
Hereafter, the embodiments of a sqairrel cage induction motor and a rotor thereof according to the present invention will be explained referring to the accompanying drawings.
Fig. 1 shows a first embodiment of the present invention and is a fragmentary perspective showing an end portion of a rotor of a squirrel cage induction motor, A rotor R1 is oppositely arranged inside a stator S1, for generating the rotational magnetic field in a predetermined interval.
The rotor RI has a rotor iron core part 2 consisting of a silicon steel plate part 2a and two back plate parts 1. In the silicon steel plate part 2a silicon steel plates are stacked in the axial direction of the rotor R1. The back plate parts 1 are mounted at respective end sides of the silicon steel plate part 2a.
The rotor iron core part 2 is held down under a predetermined pressure by tv, o iron core retainers 5a and 5b, from each end.
The back plate parts 1 constituting a part of the above stated rotor iron core part 2 are installed on respective ends of the silicon steel plate part 2a so as to transfer the pressure of :the iron core retainers 5a and 5b to the whole silicon steel plate part 2a.
o Namely, the iron core retainers 5a and 5b for holding the rotor iron core part 2 under predetermined pressure effect holding at the silicon steel plate part 2a under the inner portions of the slot parts 2b which are formed at circumferentially spaced intervals around the rotor iron .*see* core part 2.
oot 4 As stated in the above, however, in the conventional rotor R' as shown in Fig. 4, the s pressure of the iron core retainers is transferred to the silicon steel plate part 42a under the inner portions of the slot 42b of the rotor iron core part 42, but is not transferred to tooth
-I
PAOPAMEMAQUIRKPSI
1 U-BA1M6 portions, in particular to tip portions, of the rotor iron core part 42.
In this first embodiment according to the present invention, the back plate parts 1 are installed on both ends of the silicon steel plate part 2a so as to transfer the pressure of the iron core retainers 5a and 5b to the whole silicon steel plate part 2a.
In the first embodiment according to the present invention, the back plate parts 1 each consist of several steel plates 0.8 mm to 1.6 mm in thickness which are stacked and firmly fixed by for example spot welding.
In the rotor iron core part 2, circumferentially spaced slot parts 2b are formed at predetermined intervals, and outer portions thereof, namely at the circumferential face thereof, are open. Rotor conductors 2 are inserted respectively into each of the slot parts 2b.
The slot parts formed in the back plate parts 1 are larger in size than the slot parts 2b formed in the silicon steel plate part 2a, so as to prevent interference with the rotor conductors 3 due to deformation during the welding process.
The outer portions of the slot parts 2b formed in the silicon steel plate part 2a are open 20 so as to reduce the leakage magnetic flux of the slot parts 2b.
00i However, in the conventional rotor as shown in Fig. 4, in the rotor iron core part 42, the outer portions of the back plate parts 4a also are open in the same way as the slot part 42b of the silicon steel plate part 42a.
However, in the first embodiment according to the present invention, as shown in Fig.
O
1, the outer portions of the slot parts formed in the back plate parts 1 are closed.
As stated in the above, in the conventional rotor R' shown in Fig. 4, since the back plate 0 parts 41 are held at the back plate parts 41, under the inner portions of the slot parts, by the iron core retainers, the tooth portions are fixed only at the root portions of the back plate parts I'.\OPIM\JWA1U2RRI.SPf aM9 -9- 41 and are in a cantilevered state.
The slot parts of the back plate parts 41 are larger in size than the slot parts 42b of the silicon steel plate part 42a, so that the tooth portions of the back plate parts 41 are thinner than the tooth portions of the silicon steel plate part 42a and weaker in strength compared with that of the silicon steel plate part 42a and, therefore, the natural or characteristic frequency is low.
As a result, in the conventional rotor the tooth portions of the back plate parts 41 become damaged in the viciiiity of the root portions thereof, due to the tensile stress acting in the radial direction or the circumferential direction and arising by magnetic attraction and centrifugal force.
Besides, in the first embodiment according to the present invention, the outer portions of the slot parts formed in the back plate parts 1 are closed.
Since the natural or characteristic frequency of the back plate parts 1 is low, the pulsating torque generated under an inverter control and resonance in the groove with a high harmonic wave is considered to cause damage.
1: 20 According to the first embodiment of the present invention, the outer portions of the slot parts formed on the back plate parts 1 are closed and the outer portions of the slot parts formed on the back plate parts 1 are connected to each other, thereby a ring is formed in the 0 circumferential direction.
25 Consequently, the supporting condition for the tooth portions of the back plate parts 1 is changed from the cantilever state in the conventional rotor R' to the both-side fixed beam state in the rotor R1 of the first embodiment of the present invention.
0 Therefore, the rigidity of the tooth portions of the back plate parts 1 is increased and 4 the stress acting in the radial direction or the circumferential direction by the magnetic attraction and the centrifugal force is reduced.
L I'RrCAIT\,SoUIRltlU.Sr'1 3MOY6 j In other words, the tensile stress and the bending stress applied to the root portions of the tooth portions of the back plate parts 1 can be reduced and, further, the stress applied to the root portions can be dispersed.
The outer portions of the slot parts may be formed on at least one of said steel plates of the back plate part and the outer portions of the plural slot parts formed on at least one of the steel plates of the back plate part may be closed.
Fig. 2 is a fragmentary perspective view showing an end portion of a second embodiment of a rotor of a squirrel cage induction motor according to the present invention.
In the second embodiment according to the present invention, in a rotor R2, a rotor iron core part 22 has a silicon steel plate part 22a and a back plate part 21.
Outer portions of slot parts formed on the back plate part 21 are closed. At parts outwardly disposed relative to the conductors 23, and adjacent the conductors 23, the back plate part 21 has small dent portions which comprise parts of the slot parts. Spacers 24 are inserted into the respective dent portions. The outer portions of the slot parts formed on the 20 back plate part 21 are closed.
Therefore, the rigidity of the tooth portions of the back plate part 21 is increased and the stress acting in the radial direction or the circumferential direction due to the magnetic attraction and the centrifugal force is reduced In other words, the tensile stress and the bending stress applied to the root portions of the tooth portions of the back plate part 21 can be reduced and further the stress applied to the 99*9** root portions "an be dispersed.
Further, according to this second embodiment of the present invention, the outer portions of slot parts 22b formed in the silicon steel plate part 22a are open so that the leakage IWIIC~-I -e I r:\OPlRlXATOUIRItElS- rlas& d 11 magnetic flux of the slot parts 22b can be reduced.
Namely, the stack thickness of the rotor iron core part 22 is mostly occupied by the silicon steel plate part 22a, so that the leakage magnetic flux of the slot parts 22b is mainly due to the silicon steel plate part 22a.
Therefore, in the second embodiment according to the present invention, even when the outer portions of the slot parts of the back plate part 21 are closed, the leakage magnetic flux of the slot parts of the rotor iron core part 22 can be reduced and the stalling torque characteristic etc. will not be affected.
Therefore, by suppressing an increase in the leakage magnetic flux of the slot parts, a highly reliable squirrel cage induction motor and a rotor thereof can be obtained.
S.
S *•o fto I~ep-a~ II II- g Ir
Claims (2)
12- THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS: 1. A rotor of a squirrel cage induction motor comprising: a rotor iron core part having a silicon steel plate part comprised of axially stacked silicon steel plates with back plate parts respectively arranged at each end of said silicon steel plate part; first slot parts formed in said silicon steel plate part at predetermined circumferential intervals around the rotor; and S" second slot parts formed in each said back plate part at predetermined circumferential 10 intervals around the rotor and aligned with the first slot parts; wherein outer portions of said first slot parts are formed on said silicon steel plate part, S: said outer portions of said first slot parts of said silicon steel plate part being open, and outer portions of said second slot parts are formed on said back plate part, and aligned with the outer portions of the first slot par-s of the silicon steel plate part, 15 at least one said back plate part being so formed that said outer portions of said second slot parts of said at least one back plate part are closed. go 2. A rotor of a squirrel cage induction motor according to claim 1, wherein each said back plate part is formed by steel plates, and 20 said outer portions of said second slot parts of said at least one back plate part are formed on at least one of said steel plates, and said outer portions of said second slot parts formed on at least one of said steel plates of a said at least one back plate part are closed. 3. A rotor of a squirrel cage induction motor according to claim 1, wherein said outer portions of said second slot parts are formed on said at least one back plate part, and spacers are inserted into said second slot parts of said at least one back plate part. 4. A squirrel cage induction motor comprising a stator for generating a rotational magnetic field; and a rotor arranged oppositely with said stator and having a rotor iron core part; and retainers for holding said rotor iron core part at both end sides thereof; ~LP~B8 rrrrs~---~ I'I\OI'IRy IfS69 -M5, l /1 /W6 13 said rotor iron core part having a silicon steel plate part comprised of axially stacked silicon steel plates with back plate parts respectively arranged at each end of said silicon steel plate part; first slot parts formed in said silicon steel plate part at predetermined circumferential intervals around the rotor; and second slot parts formed in each said back plate part at predetermined circumferential intervals around the rotor and aligned with the first slot parts; wherein outer portions of said first slot parts are formed on said silicon steel plate part, said outer portions of said first plural slot parts of said silicon steel plate part being 10 open, and outer portions of said second slot parts are formed on said back plate part, and aligned 1 with the outer portions of the first slot part of the silicon steel plate part, at least one said back plate part being Fio formed that said outer portions of said second slot parts of said at least one back plate part being closed. 5. A squirrel cage induction motor according to claim 4, wherein each said back plate part is formed by steel plates, and o said outer portions of said second slot parts of said at least one back plate part are formed on at least one of said steel plates, and 20 said outer portions of said second slot parts formed on at least one of said steel plates of a said at least one back plate are closed, 6. A squirrel cage induction motor according to claim 4, wherein said outer portions of said second slot parts are formed on said at least one back plate part, and spacers are inserted into said second slot parts of each said at least one back plate part. 7. A rotor of a squirrel cage induction motor according to any one of claims 1 to 3, wherein both said end back plate parts are formed in the same way as said at least one back plate part. i i i 1 Vit 1AO11\0 KA'J\OUUAKItI4I.l 100a96
14- 8. A squirrel cage induction motor according to any one of claims 4 to 6, wherein both said end back plate parts are formed in the same way as said at least one back plate part. 9. A rotor of a squirrel cage induction motor substantially as hereinbefore described with reference to the drawings. A squirrel cage induction motor substantially as hereinbefore described with reference to the drawings. DATED this THIRD day of APRIL 1996 Hitachi, Ltd by DAVIES COLLISON CAVE Patent Attorneys for the applicant(s) 0 e 4O 0 4 4 4 o* 0e 444 4 *oo I 4 **o *ooo Abstract of Disclosure: The strength of a back plate part can be ensured by suppressing an increase in the leakage magnetic flux of plural slot parts of a rotor iron core part. Among plural slot parts formed in a circumferential direction of the rotor iron core part at a predetermined interval, upper portions of plural slot parts formed in a silicon steel plate part are opened and upper portions of slot 10 parts formed in the back plate part are closed. A highly reliability squirrel cage induction motor and a rotor thereof can be obtained. •go •ooeo Io, echo o• o'oo
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP09105994A JP3340555B2 (en) | 1994-04-28 | 1994-04-28 | Cage induction motor and its rotor |
JP6-91059 | 1994-04-28 |
Publications (2)
Publication Number | Publication Date |
---|---|
AU1656995A AU1656995A (en) | 1995-11-16 |
AU675385B2 true AU675385B2 (en) | 1997-01-30 |
Family
ID=14015936
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
AU16569/95A Ceased AU675385B2 (en) | 1994-04-28 | 1995-04-20 | Squirrel cage induction motor and rotor thereof |
Country Status (3)
Country | Link |
---|---|
JP (1) | JP3340555B2 (en) |
AU (1) | AU675385B2 (en) |
ZA (1) | ZA953404B (en) |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2011087375A (en) * | 2009-10-14 | 2011-04-28 | Railway Technical Res Inst | Induction motor |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE3502697A1 (en) * | 1984-11-29 | 1986-06-05 | BBC Aktiengesellschaft Brown, Boveri & Cie., Baden, Aargau | Asynchronous rotor |
EP0275320A1 (en) * | 1986-07-03 | 1988-07-27 | Fanuc Ltd. | Structure of a squirrel-cage rotor |
US5097166A (en) * | 1990-09-24 | 1992-03-17 | Reuland Electric | Rotor lamination for an AC permanent magnet synchronous motor |
-
1994
- 1994-04-28 JP JP09105994A patent/JP3340555B2/en not_active Expired - Fee Related
-
1995
- 1995-04-20 AU AU16569/95A patent/AU675385B2/en not_active Ceased
- 1995-04-26 ZA ZA953404A patent/ZA953404B/en unknown
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE3502697A1 (en) * | 1984-11-29 | 1986-06-05 | BBC Aktiengesellschaft Brown, Boveri & Cie., Baden, Aargau | Asynchronous rotor |
EP0275320A1 (en) * | 1986-07-03 | 1988-07-27 | Fanuc Ltd. | Structure of a squirrel-cage rotor |
US5097166A (en) * | 1990-09-24 | 1992-03-17 | Reuland Electric | Rotor lamination for an AC permanent magnet synchronous motor |
Also Published As
Publication number | Publication date |
---|---|
AU1656995A (en) | 1995-11-16 |
JPH07298583A (en) | 1995-11-10 |
ZA953404B (en) | 1996-01-10 |
JP3340555B2 (en) | 2002-11-05 |
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