United States Patent [19]
`Hirano et al.
`
`[54] STATOR FOR AN ELECTRIC MOTOR
`
`[75]
`
`Inventors: Mikio ffirano, Tondabayashi; Seiji
`Kikuchi, Nishinoroiya; Manabu
`Takeuchi, Daito; ffiroshi Kawazoe;
`Kouzi Fukuda, both of Hirakata;
`Takashi Akiyama, Osaka; Koichi
`Nakatsukasa, Sanda; ffideki
`Yamanaka, Kadoma; Kazunori
`Morita, !koma, all of Japan
`
`[73] Assignee: Matsushita Electric Industrial Co.,
`Ltd., Osaka, Japan
`
`[21] Appl. No.: 123,383
`
`[22] Filed:
`
`Sep. 20, 1993
`
`[30]
`
`Foreign Application Priority Data
`
`[IP]
`
`Japan .................................... 4-254321
`
`Sep. 24, 1992
`Int. CI.6
`••••••••••••••••••••••••••••••••••••••••••••••••••••••• B02K 1/16
`[51]
`[52] U.S. CI ........................... 3101258; 310/179; 310/254;
`310/42; 3101217
`[58] Field of Search ..................................... 310/217, 254,
`3101258, 179,216,218,42
`
`[56]
`
`References Ci~d
`
`U.S. PATENT DOCUMENTS
`
`1,756,672
`1,779,950
`1,901,315
`2,688,103
`
`4/1930 Barr ........................................ 3101217
`10/1930 Reichel ................................... 3101254
`3/1933 McCarty .............•................... 3101254
`8/1954 Sheldon .................................. 3101254
`
`1111I11111111111111_m III III 111111111
`5,729,072
`Mar. 17, 1998
`
`USOO5729072A
`[11] Patent Number:
`[45] Date of Patent:
`
`2,774,000
`3,056,896
`3,260,875
`4,217,510
`5,256,926
`5,583,387
`
`1211956 Ross ........................................ 3101216
`10/1962 Ludemann .............................. 3101216
`7/1966 Evans ...................................... 3101217
`811980 Detinko ................................... 3101258
`10/1993 Hagen10cher ..........••••..••••..•.... 3101259
`1211996 Takeuchi et aI. . ...................... 3101217
`
`Primary Examiner-Steven L. Stephan
`Assistant Examiner-Judson H. Jones
`Attome}\ Agent, or Fi~Watson Cole Stevens Davis,
`P.L.L.c.
`
`[57]
`
`ABSTRACT
`
`In a stator for an electric motor, insulating members are
`formed on laminated iron cores divided for each pole-tooth
`unit in the direction of the output shaft and windings are
`applied perpendicularly to the pole-tooth portions in a
`high-density alignment. After a predetermined number of
`the laminated iron cores are combined so as to form a
`cylindrical configuration, they are welded at the outer end
`portions of the dividing surfaces in the direction of lamina(cid:173)
`tion so as to construct an integral structure stator with
`rigidity, thereby enabling high densification of the windings
`(conductor space factor of 70%) and space-savings in the
`winding end portions. Further, as any joint portions between
`the pole-tooth portions are not necessary, reduction (5 to
`10%) in motor efficiency due to such joint portions can be
`prevented, and, as any integrally forming by resinous mem(cid:173)
`bers is not necessary, inter-winding short-circuiting is not
`caused. Welding may be replaced by adhesive bonding.
`Otherwise, an annular member may be employed to form an
`integral structure of the divided iron core lamination.
`
`7 Claims, 3 Drawing Sheets
`
`16 13 1211
`
`14
`
`Page 1 of 7
`
`PETITIONERS' EXHIBIT 1012
`
`

`

`u.s. Patent
`
`Mar. 17, 1998
`
`Sheet 1 of 3
`
`5,729,072
`
`FIG. I
`
`FIG. 2
`
`23
`
`Page 2 of 7
`
`

`

`u.s. Patent
`
`Mar. 17, 1998
`
`Sheet 2 of 3
`
`5,729,072
`
`FIG. 3
`
`FIG. 4
`
`PRIOR ART
`
`Page 3 of 7
`
`

`

`u.s. Patent
`
`Mar. 17, 1998
`
`Sheet 3 of 3
`
`5,729,072
`
`FIG. 5A PRIOR ART
`
`FIG. 58 PRIOR ART
`
`10
`
`Page 4 of 7
`
`

`

`5,729,072
`
`1
`STATOR FOR AN ELECTRIC MOTOR
`
`BACKGROUND OF THE INVENTION
`
`2
`pole-tooth portions, the joint portions 3 connecting the
`pole-tooth portions at their inner parts are indispensable in
`order to structure and maintain the second iron core
`member 2.
`5 (2) In the joint portions 3 indispensable as aboves~d,
`magnetic leakage occurs between the pole-teeth, causmg
`a problem that the motor efficiency drops by 5 to 10%, and
`this requires the joint portions 3 to be formed as thinly as
`possible.
`(3) Therefore a need arises so as to form the resinous part 6
`in order for the rigidity of the stator structure to be
`properly given; however, a problem arrises that an inter(cid:173)
`winding short-circuiting tends to be caused as a result of
`a damage of the insulating sheathes of the windings S at
`the time of forming such resinous part 6.
`(4) Besides, the inconvenience arises that, following the
`necessity of a larger iron core, a larger press equipment
`and molding apparatus become necessary, and productive
`efficiency is reduced.
`Furthermore, in the foregoing second conventional
`construction, the perpendicular winding of the windings 9
`around the outer periphery of the laminated iron core 7
`renders the windings not in alignment and does impose the
`linritation of conductor space factor at 52 to 55%. Moreover,
`while space-saving for the winding end portion is possible,
`the dimension increases as the windings extend over in the
`direction of the outer diameter.
`SUMMARY OF THE INVENTION
`The present invention has for its object to solve the
`foregoing conventional problems and provides a stator for
`an electric motor which, while maintaining the construction
`which enables high-density aligning winding to be carried
`out at an outside place, is designed to effect space-saving for
`the winding end portions, eliminates such joint portions
`between the pole-teeth which tend to reduce the motor
`efficiency, also eliminates forming of such resinous part
`hitherto required to ensure the stator rigidity, and yet has a
`divided construction which enables a large-sized iron core to
`be produced with a small-sized press equipment
`In order to achieve this object, a stator for an electric
`motor according to the present invention comprises lami(cid:173)
`nated iron cores divided for each pole-tooth unit and wind(cid:173)
`ings wound perpendicularly to the pole-tooth portions of the
`laruinated iron cores, wherein a predetermined number of
`the laminated iron cores are combined so as to form a
`cylindrical form and thereafter the laminated iron cores are
`made integral by welding, bonding or applying an annular
`member.
`By virtue of this construction,
`(1) As the iron cores are divided for pole-tooth unit, it
`becomes possible to wind up the windings perpendicu(cid:173)
`larly around the pole-tooth portion in a high density in
`alignment (a conductor space factor of 70%) at an outside
`place for an individual set of the laminated cores, and
`space-saving in the winding end portions is performed.
`(2) As it is possible to obtain the necessary rigidity of the
`stator by welding, bonding or applying an annular mem(cid:173)
`ber after a predetermined number of the iron core are
`combined so as to form a cylindrical form, such resinous
`part becomes unnecessary and such inter-winding short(cid:173)
`circuiting is prevented from occurring. Further, since such
`joint portions for the pole-teeth portions to construct and
`maintain the integral iron core are made unnecessary, it is
`possible to prevent a reduction in motor efficiency by 5 to
`10% due to such joint portions.
`(3) As the laminated iron core is divided for pole-tooth unit,
`even a large-sized iron core can be produced with a
`
`1. Field of the Invention
`The field to which the present invention relates is gener(cid:173)
`ally a stator for an electric motor.
`In recent years, for the purposes of rendering an electric
`motor compact and highly efficient, a need of rendering
`stator windings highly densified and saving space for wind- 10
`ing end portions has been increasingly arising. In particular,
`in a servo-motor used in industrial robots and others, in
`order to meet the recent demand for achieving a high-speed
`robotic operation, saving space and obtaining an increased
`output, it has become necessary that a magnet of an 15
`extremely high magnetic :flux density be employed for a
`rotor, that the winding density of the stator reach a conductor
`space factor of 70% which represents the theoreticallinrit
`value of aligning windings, and that space for the winding
`end portions be made to minimum. While there has hitherto 20
`been an inserter winding as a winding technique for attain(cid:173)
`ing high densification, it entails the problem of causing the
`space for the winding end portions to be extremely large.
`Accordingly, it is the recent trend to seek to enable simul(cid:173)
`taneously the windings of an increased density and the 25
`space-saving for the winding end portions to be achieved by
`dividing the iron core and effecting the windings in align(cid:173)
`ment at an outside place.
`2. Description of the Prior Art
`The constructions of conventional stators will now be 30
`described below.
`FIG. 4 shows the construction of a stator aimed to highly
`densify its windings and to save the space for the winding
`end portions. In FIG. 4, numeral I designates a first iron core 35
`member constituting the outer part of an iron core whereas
`numeral 2 designates a second iron core member constitut(cid:173)
`ing the inner part of the iron core. Numeral 3 designates a
`joint portion connecting adjacent pole-tooth portions of the
`second iron core member. Numeral 4 designates an insulator,
`numeral S designates windings and numeral 6 denotes a
`resinous part.
`In the above construction, the windings S are wound
`perpendicularly around the insulator 4 in a high density in
`alignment at an outside place, and a predetermined number 45
`of such windings S are inserted on the pole-tooth portions of
`the second iron core member 2. Thereafter, the second iron
`core member 2 is inserted into the first iron core member I
`to constitute the stator iron core. In addition, the resinous
`part is formed by molding or the like to complete the integral 50
`structure of the stator.
`Next, FIGS. SA and SB show the construction of another
`conventional and typical stator in which a laminated iron
`core is divided in the direction of its output shaft. In FIG.
`SA, numeral 7 designates a laminated iron core which is 55
`divided into two by a dividing surface 8. Numeral 9 desig(cid:173)
`nates windings. In FIG. SB, numeral 10 designates a resin(cid:173)
`ous part.
`In the above construction, the windings 9 are perpendicu(cid:173)
`larly wound around the outer periphery of the laminated iron 60
`core 7 divided into the two parts. Thereafter, the laminated
`iron core 7 is matched at the dividing surfaces 8 and is made
`integral with the resinous part 10.
`The foregoing first conventional constructions, however,
`involves the following problems:
`(1) Due to the fact that the iron core constituting the stator
`is divided at the outer circumferential surfaces of the
`
`40
`
`65
`
`Page 5 of 7
`
`

`

`5,729,072
`
`3
`small-sized press equipment, and production efficiency is
`markedly enhanced.
`
`BRIEF DESCRIPTION OF TIIE DRAWINGS
`
`FIG. 1 is a top plan view partly in cross-section illustrat(cid:173)
`ing a stator in a first embodiment of the present invention;
`FIG. 2 is a top plan view partly in cross-section illustrat(cid:173)
`ing a stator in a second embodiment of the present invention;
`FIG. 3 is a top plan view partly in cross-section illustrat(cid:173)
`ing a stator in a third embodiment of the present invention;
`AG. 4 is a top plan view partly in cross-section illustrat(cid:173)
`ing a conventional stator of the prior art;
`AG. 5A is a perspective view illustrating another con(cid:173)
`ventional stator of the prior art before resinous part is
`applied; and
`AG. 5B is a side cross-sectional view illustrating the
`conventional stator of FIG. SA.
`
`DEfAll..ED DESCRIPTION OF THE
`INVENTION
`
`Hereinafter, several embodiments of the present invention
`will now be described with reference to the accompanying
`drawings.
`
`EMBODIMENT 1
`
`4
`insulating members formed on the pole-tooth portions of the
`laminated iron cores 21, numeral 23 designates windings,
`numeral 24 designates dividing surfaces of the iron cores
`and numeral 25 designates projections. These are like those
`5 of the construction illustrated in FIG. 1. Unlike the con(cid:173)
`struction of AG. 1, however, here, bonding layers 26 are
`provided in lieu of the welded portions 16.
`In the stator for an electric motor being constructed as
`above, the laminated iron cores 21 are, after being laminated
`10 for each pole-tooth unit by means of a small-sized press
`equipment, given the insulating members 22 on the pole(cid:173)
`tooth portions, and the windings 23 are formed in a high(cid:173)
`density in alignment by means of an appropriate winding
`machine at an outside place. Thereafter, the laminated iron
`15 cores 21 are combined in a predetermined number with the
`projections 2S on the dividing surfaces 24 so as to form a
`cylindrical configuration, and, by an extremely thin bonding
`layer 26 having been applied at each dividing surface 24
`beforehand, an integral structure with necessary rigidity as
`20 a stator is obtained.
`According to this embodiment, by forming the laminated
`iron cores 21 being divided for each pole-tooth unit and
`providing the windings 23 in high-density alignment for
`each pole-tooth unit, a conductor space factor of 70% can be
`25 obtained. Further, by forming the bonding layers 26 on the
`dividing surfaces 24 of the laminated iron cores 21 so as to
`construct an integral structure, such joint portions 3 in the
`prior art illustrated in FIG. 4 are made unnecessary, and it
`becomes possible to prevent such drops of 5 to 10% in motor
`30 efficiency. Further, such resinous part 6 becomes
`unnecessary, and a stabilized stator without such inter(cid:173)
`winding short-circuiting is obtained. Furthermore, by the
`laminated iron cores being finely divided, a small-sized
`press equipment can be utilized, thus remarkably enhancing
`35 the production efficiency.
`
`EMBODIMENf 3
`In FIG. 3, numeral 31 designates laminated iron cores
`divided for each pole-tooth unit, numeral 32 designates
`insulating members formed on the pole-tooth portions of the
`laminated iron cores 31, numeral 33 designates windings,
`and numeral 34 designates dividing surfaces of the lami(cid:173)
`nated iron cores. These are like those of the construction
`illustrated in FIG. 1. Unlike the construction of AG. 1,
`however, here, an annular member 35 is provided in lieu of
`the welded portions 16.
`In the stator for an electric motor constructed as above,
`the laminated iron cores 31 are, after being laminated for
`each pole-tooth unit by means of a small-sized press
`equipment, given the insulating members 32 on the pole-
`tooth portions, and the windings 33 are formed in a high(cid:173)
`density in alignment by means of an appropriate winding
`machine at an outside place. Thereafter, the laminated iron
`cores 31 are combined in a predetermined number with the
`dividing surfaces 34 so as to form a cylindrical
`configuration, and then, they are inserted in the annular
`member 35 with an appropriate interference, being urged in
`the direction to the inner diameter; thus an integral structure
`with necessary rigidity as a stator is obtained.
`According to this embodiment, by forming the laminated
`iron cores 31 being divided for each pole-tooth unit and
`providing the windings 33 in high-density alignment for
`pole-tooth unit, a conductor space factor of 70% can be
`65 obtained. Further, by providing the annular member 35 on
`the outer periphery of the laminated iron cores 31 and
`preSSing the latter in the direction to the inner diameter to
`
`In AG. 1, numeral 11 designates laminated iron cores
`divided for each pole-tooth unit, numeral 12 designates
`insulating members formed on the pole-tooth portions of the
`laminated iron cores 11. numeral 13 designates windings,
`numeral 14 designates dividing surfaces of the divided iron
`cores, and numeral 15 designates projections, and numeral
`16 designates welded portions.
`In the stator for an electric motor constructed as above,
`the laminated iron cores 11 are, after being laminated for
`each pole-tooth unit by means of a small-sized press
`equipment, given the insulating members 12 on the pole(cid:173)
`tooth portion, and the windings 13 are formed in a high 40
`density in alignment by means of an appropriate winding
`machine at the outside place. Thereafter, a predetermined
`number of the laminated iron cores 11 are combined with the
`projections 15 on the dividing surfaces 14 so as to form a
`cylindrical configuration, and then the outer end portions of 45
`the dividing surfaces are laser-welded in the direction of
`lamination to form the welded portions 16. thereby consti(cid:173)
`tuting an integral structure with necessary stator rigidity.
`According to this embodiment, by forming the laminated
`iron cores 11 in dividing for pole-tooth unit and providing 50
`the windings 13 in high-density alignment for each pole(cid:173)
`tooth unit, a conductor space factor of 70% can be obtained.
`Further. by forming the welded portions 16 at the outer end
`portions of the dividing surfaces 14 of the laminated iron
`cores 11 to construct an integral structure, such joint portions 55
`3 in the prior art illustrated in FIG. 4 are made unnecessary,
`and it becomes possible to prevent such drops by 5 to 10%
`in motor efficiency. Further, such resinous part 6 is also
`made unnecessary. and a stabilized stator assembly without
`inter-windings' short-circuiting are obtained. Furthermore, 60
`by the laminated iron cores being finely divided, a small(cid:173)
`sized press equipment can be utilized, thus remarkably
`enhancing the production efficiency.
`
`EMBODIMENf 2
`In AG. 2, numeral 21 designates laminated iron cores
`divided for each pole-tooth unit, numeral 22 designates
`
`Page 6 of 7
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`

`

`5,729,072
`
`10
`
`5
`obtain an integral structure, such joint portions 3 in the prior
`art illustrated in FlG. 4 are made unnecessary, and it
`becomes possible to prevent such drops of 5 to 10% in motor
`efficiency. Further, such resinous part 6 becomes
`unnecessary, and a stabilized stator without inter-winding 5
`short-circuiting is obtained. Furthermore, by the laminated
`iron cores being finely divided, a small-sized press equip(cid:173)
`ment can be utilized, thus remarkably enhancing the pro(cid:173)
`duction efficiency.
`At this point, it will readily be understood that in the first
`embodiment, the necessary rigidity of the stator structure is
`obtained by the welded portions 16 themselves; however,
`the bonding layers 26 in the second embodiment and/or the
`annular member 35 in the third embodiment may be jointly
`used in combination to obtain a stator structure of more 15
`increased rigidity.
`As described in the foregoing, the present invention
`provides a stator assembly for a rotary electric motor which
`comprises laminated iron cores divided for each pole-tooth
`unit and windings wound perpendicular to the pole-tooth 20
`portions of the laminated iron cores, wherein, after a pre(cid:173)
`determined number of the laminated iron cores are held so
`as to build up a cylindrical form, such iron cores are made
`integral by welding, bonding, or applying an annular
`member, thereby obtaining a superior stator assembly not
`available heretofore, which enables high densification of the
`windings (with a conductor space factor of 70%), and
`elimination of the joint portions hitherto required between
`adjacent pole-teeth, and achieves space-saving and a large
`enhancement of motor efficiency, and besides highly
`improves the production stability and efficiency markedly by
`virtue of fine division of the laminated iron cores.
`We claim:
`1. A stator for an electric motor, said stator comprising:
`a plurality of cores, each of the plurality of cores corre-
`sponding to a pole-tooth unit of the electric motor and
`comprising a pole-tooth portion and an outer portion
`with an outer surface and dividing surfaces, said divid(cid:173)
`ing surfaces extending parallel to a longitudinal axis of
`said electric motor, said plurality of cores being 40
`arranged in a cylindrical configuration, and adjacent
`ones of said plurality of cores being rigidly fixed
`together along said dividing surfaces; and
`windings wound around the pole-tooth portions of the
`plurality of cores such that each of the windings is
`wound around a single one of the pole-tooth portions;
`wherein the plurality of cores are bonded at the dividing
`surfaces.
`2. A stator for an electric motor, said stator comprising:
`a plurality of cores. each of the plurality of cores corre(cid:173)
`sponding to a pole-tooth unit of the electric motor and
`comprising a pole-tooth portion and an outer portion
`
`6
`with an outer surface and dividing surfaces, said divid(cid:173)
`ing surfaces extending parallel to a longitudinal axis of
`said electric motor, said plurality of cores being
`arranged in a cylindrical configuration, and adjacent
`ones of said plurality of cores being rigidly fixed
`together along said dividing surfaces; and
`windings wound around the pole-tooth portions of the
`plurality of cores such that each of the windings is
`wound around a single one of the pole-tooth portions;
`wherein the plurality of cores are welded together along
`the dividing surfaces.
`3. A stator for an electric motor, said stator comprising:
`a plurality of cores, each of the plurality of cores corre(cid:173)
`sponding to a pole-tooth unit of the electric motor and
`comprising a pole-tooth portion and an outer portion
`with an outer surface and dividing surfaces, said divid-
`ing surfaces extending parallel to a longitudinal axis of
`said electric motor, said plurality of cores being
`arranged in a cylindrical configuration, and adjacent
`ones of said plurality of cores being rigidly fixed
`together along said dividing surfaces; and
`windings wound around the pole-tooth portions of the
`plurality of cores such that each of the windings is
`wound around a single one of the pole-tooth portions;
`25 wherein each of the plurality of cores comprises a pro-
`jection and an indentation at said outer portion, said
`adjacent ones of said plurality of cores being engaged
`by means of said projection and said indentation.
`4. A stator according to claim 1, further comprising an
`30 annular member arranged on the outer surface of each of the
`plurality of cores to hold the plurality of cores in the
`cylindrical configuration and to urge the plurality of cores
`inwardly.
`5. A stator according to claim 2, further comprising an
`35 annular member arranged on the outer surface of each of the
`plurality of cores to hold the plurality of cores in the
`cylindrical configuration and to urge the plurality of cores
`inwardly.
`6. A stator according to claim 3, further comprising an
`annular member arranged on the outer surface of each of the
`plurality of cores to hold the plurality of cores in the
`cylindrical configuration and to urge the plurality of cores
`inwardly.
`7. A stator according to claim 2, further comprising an
`45 annular member arranged on the outer surface of each of the
`plurality of cores to hold the plurality of cores in the
`cylindrical configuration and to urge the plurality of cores
`inwardly, and wherein each of the plurality of cores com(cid:173)
`prises a projection and an indentation at said outer portion,
`50 said adjacent ones of said plurality of cores being engaged
`by means of said projection and said indentation.
`
`* * * * *
`
`Page 7 of 7
`
`