Case 1:17-cv-00300-UNA Document 1-2 Filed 03/20/17 Page 1 of 18 PageID #: 35
`Case 1:17—cv—OO300—UNA Document 1-2 Filed 03/20/17 Page 1 of 18 Page|D #: 35
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`EXHIBIT 2
`
`EXHIBIT 2
`
`

`

`Case 1:17-cv-00300-UNA Document 1-2 Filed 03/20/17 Page 2 of 18 PageID #: 36
`
`U 7604746
`
`UNITED STATES DEPARTMENT OF COMMERCE
`
`United States Patent and Trademark Office
`
`September 29, 2016
`
`THIS IS TO CERTIFY THAT ANNEXED HERETO IS A TRUE COPY FROM
`
`THE RECORDS OF THIS OFFICE OF:
`
`U.S. PATENT: 7,067,952
`
`ISSUE DATE: June 27, 2006
`
`By Authority of the
`Under Secretary of Commerce for Intellectual Property
`and Director of the United States Patent and Trademark Office
`
`R GLOVER
`
`Certifying Officer
`
`

`

`I I!111 IIIIIIli III IIIII IIIII IIIII IIIII IIIII IIIii IIIII IIIli IIII!1 Iill IIII IIII
`Case 1:17-cv-00300-UNA Document 1-2 Filed 03/20/17 Page 3 of 18 PageID #: 37
`US007067952B2
`
`(12) United States Patent
`Neal
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 7,067,952 B2
`Jun. 27, 2006
`
`(54) STATOR ASSEMBLY MADE FROM A
`MOLDED WEB OF CORE SEGMENTS AND
`MOTOR USING SAME
`
`(75)
`
`Inventor: Griffith D. Neal, Alameda, CA (US)
`
`(73) Assignee: Encap Motor Corporation, Alameda,
`CA (US)
`
`( * ) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 248 days.
`
`(21)
`
`Appl. No.: 10/383,219
`
`(22)
`
`Filed:
`
`Mar. 5, 2003
`
`(65)
`
`Prior Publication Data
`
`US 2004/0034988 A1
`
`Feb. 26, 2004
`
`Related U.S. Application Data
`
`(63)
`
`Continuation-in-part of application No. 09/798,511,
`filed on Mar. 2, 2001, now Pat. No. 7,036,207.
`
`(51)
`
`(52)
`
`(58)
`
`(56)
`
`Int. CI.
`HO2K 1/18
`(2006.01)
`HO2K 15/02
`(2006.01)
`HO2K 15/10
`(2006.01)
`U.S. CI ........................... 310/259; 310/42; 310/45;
`310/218
`Field of Classification Search ............ 310/42-43,
`310/45, 216-218, 254, 259; 244/432, 433,
`244/433.4; 29/596
`See application file for complete search history.
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
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`
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`
`Primary Examiner--Burton Mullins
`(74) Attorney, Agent, or Firm--Steven P. Shurtz; Brinks
`Hofer Gilson & Lione
`
`(57)
`
`ABSTRACT
`
`A plurality of stator arc segments 20 are linked together by
`a phase change material 22 enabling simplified winding and
`higher slot fill. Once wound this continuous structure can be
`formed into a toroidal core 17 for a stator assembly 40 used
`to make a motor 100. In a preferred embodiment, a mono-
`lithic body 42 of phase change material substantially encap-
`sulates the conductors and holds the stator arc segments 20
`in contact with each other in the toroidal core 17. Hard disc
`drives using the motor 100, and methods of constructing the
`motor 100 are also disclosed.
`
`14 Claims, 5 Drawing Sheets
`
`22
`
`f6
`
`Copy providedby USPTO from the PIRS Image Database on 09/28/2016
`
`

`

`Case 1:17-cv-00300-UNA Document 1-2 Filed 03/20/17 Page 4 of 18 PageID #: 38
`US 7,067,952 B2
`Page 2
`
`PATENT DOCUMENTS
`
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`
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`
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`
`BE
`DE
`EP
`EP
`FR
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`J-P
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`JP
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`SU
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`WO
`WO
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`
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`
`OTHER PUBLICATIONS
`
`Product Information from Dupont Engineering Polymers
`"
`entitled
`"El "
`ectncalfElectromc Thermoplastic Encapsula-
`tion," undated, Publ. Reorder No.: H-58633 (R, 96.7), 20
`pages.
`LNP Engineering Plastics, Press Release entitled "LNP
`Introduces First-Ever Line of Thermally Conductive Com-
`pounds," Jan. 28, 1999 (2 pages).
`Buchanan Motor Works, Inc., article from the Internet
`entitled "’Epoxy Seal--Prevents Down Time and Keeps
`Equipment Running Longer," Jul. 14, 1999, <http://www.
`bmwworks.comlVIP.htm>, 1 page.
`
`Copy provided by USPTO from the PIRS Image Database on 09/2812016
`
`

`

`Case 1:17-cv-00300-UNA Document 1-2 Filed 03/20/17 Page 5 of 18 PageID #: 39
`
`US 7,067,952 B2
`Page 3
`
`The Epoxylite Corporation, article from the Intemet entitled
`"Vacuum Pressure Impregnation (VPI) Systems", Nov. 19,
`1999, <http ://www.ep oxylite.c om/Ep oxyliteEquipment.
`htm>, 3 pages.
`
`Neeltran Inc., article from the Internet entitled "Vacuum
`Pressure Impregnation (VPI)", Nov. 19, 1999, <http://www.
`neeltran.thomasregister.com/olc/neeltraigneel9.htm>
`pages.
`* cited by examiner
`
`2
`
`Copy provided by USPTO from the PIRS Image Database on 09/28/2016
`
`

`

`Case 1:17-cv-00300-UNA Document 1-2 Filed 03/20/17 Page 6 of 18 PageID #: 40
`U.S. Patent
`US 7,067,952 B2
`Jun. 27, 2006
`Sheet 1 of 5
`
`PR I OR ART
`
`2
`
`F 20
`
`~i
`
`28
`
`Copy provided by USPTO from the PIRS Image Database on 09/28/2016
`
`~, ii;:~; ..... ...........
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`

`

`Case 1:17-cv-00300-UNA Document 1-2 Filed 03/20/17 Page 7 of 18 PageID #: 41
`U.S. Patent
`
`US 7,067,952 B2
`
`Jun. 27, 2006
`
`Sheet 2 of 5
`
`FIG.3
`
`16
`
`22
`
`FIG.4
`
`25
`
`19
`
`FIG.5
`
`2
`
`I
`
`19
`
`19
`
`20
`
`22
`
`19
`
`21B
`
`21A
`
`Copy provided by USPTO from the PIRS Image Database on 09/28/2016
`
`

`

`Case 1:17-cv-00300-UNA Document 1-2 Filed 03/20/17 Page 8 of 18 PageID #: 42
`
`U.S. Patent
`
`Jun. 27, 2006
`
`Sheet 3 of 5
`
`US 7,067,952 B2
`
`FIG.6
`
`15
`
`21C
`
`21B
`
`FIG.7
`
`16
`
`Copy provided by USPTO from the PIRS Image Database on 09/28/2016
`
`

`

`Case 1:17-cv-00300-UNA Document 1-2 Filed 03/20/17 Page 9 of 18 PageID #: 43
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`U.S. Patent
`
`Jun. 27, 2006
`
`Sheet 4 of 5
`
`US 7,067,952 B2
`
`FIG. 8c~
`
`6
`
`61
`
`66
`
`15
`
`17
`
`61
`
`~61
`
`FIG. 8b
`
`61
`
`42 61
`
`Copy provided by USPTu from the PIRS Image Database on 09/28/2016
`
`

`

`Case 1:17-cv-00300-UNA Document 1-2 Filed 03/20/17 Page 10 of 18 PageID #: 44
`U.S. Patent
`
`US 7,067,952 B2
`
`Jun. 27, 2006
`
`Sheet 5 of 5
`
`f
`
`I07
`
`52
`5O
`
`102
`
`40
`
`103-
`
`52
`50
`
`22
`
`225
`
`224
`
`.220
`
`Copy provided by USPTO from the PIRS Image Database on 09/28/2016
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`

`

`Case 1:17-cv-00300-UNA Document 1-2 Filed 03/20/17 Page 11 of 18 PageID #: 45
`US 7,067,952 B2
`
`1
`STATOR ASSEMBLY MADE FROM A
`MOLDED WEB OF CORE SEGMENTS AND
`MOTOR USING SAME
`
`REFERENCE TO EARLIER FILED
`APPLICATION
`
`The present application is a continuation-in-part of appli-
`cation Ser. No. 09/798,511, filed Mar. 2, 2001, now U.S. Pat.
`No. 7,036,207, and entitled Stator Assembly Made From A
`Plurality Of Toroidal Core Arc Segments And Motor Using
`Same, which is hereby incorporated by reference.
`
`FIELD OF THE INVENTION
`
`2
`various components of the motor. Greater dimensional con-
`sistency between components leads to a smaller gap between
`the stator 4 and the magnet 3, producing more force, which
`provides more torque and enables faster acceleration and
`5 higher rotational speeds.
`The conventional method of forming stators has a number
`of drawbacks. First, most steel is manufactured in rolled
`sheets and thus has a grain orientation. The grain orientation
`has an effect on the magnetic flux properties of the steel. In
`10 circular stamped pieces of steel, the grain orientation differs
`at different points around the circle. Compared from the
`radius line of the circle, the grain orientation is sometimes
`aligned along the radius, sometimes transverse to it, and
`mostly at a varying angle to the radius. The un-aligned grain
`structure of conventional stators causes the magnetic flux
`values to differ in parts of the stator, and thus the motor does
`not have consistent and uniform torque properties as it
`rotates.
`Another drawback with using circular steel pieces is that,
`especially for inward facing poles, it has been difficult to
`wind the wire windings tightly because of the cramped space
`to work inside of the laminated stator core. The cramped
`working space creates a lower limit on the size of the stator
`and thus the motor. The limited working space also results
`25 ill a low packing density of wire. The packing density of
`wire coiled around the poles affects the amount of power
`generated by the motor. Increasing packing density increases
`the power and thus the efficiency of the spindle motor.
`An important factor in motor design is to reduce stack up
`3o tolerances in the motor. Stack up tolerances reduce the
`overall dimensional consistency between the components.
`Stack up tolerances refer to the sum of the variation of all the
`tolerances of all the parts, as well as the overall tolerance
`that relates to the alignment of the parts relative to one
`35 another. One source ~>f stack up tolerances is from the
`circular stator body. Generally, the thickness of rolled steel
`is not uniform across the width of the roll. Sometimes the
`edges are thicker or thinner than the center. In a stator made
`from circular stamped pieces, the thicknesses of individual
`4o laminations are thus different from one side to the other.
`When stacked together, this creates a stack up tolerance
`problem. Furthermore, the circular stampings leave a lot of
`wasted steel that is removed and must be recycled or
`discarded.
`45 Another important factor in motor design is the lowering
`of the operating temperature of the motor. Increased motor
`temperature affects the electrical ef~ciency of the motor and
`bearing life. As temperature increases, resistive loses in wire
`increase, thereby reducing total motor power. Furthermore,
`50 the Arhennius equation predicts that the failure rate of an
`electrical device is exponentially related to its operating
`temperature. The frictional heat generated by bearings
`increases with speed. Also, as bearings get hot they expand,
`and the bearing cages get stressed and may deflect, causing
`55 non-uniform rotation, reducing bearing life. This non-tmi-
`form rotation causes a further problem of limiting the ability
`of the servo system controlling the read/write heads to
`follow data tracks on the magnetic media. One drawback
`with existing motor designs is their limited effective dissi-
`6o pation of the heat, and difficulty in incorporating heat sinks
`to aid in heat dissipation. In addition, in current motors the
`operating temperatures generally increase as the size of the
`motor is decreased.
`Manufacturers have established strict requirements on the
`65 outgassing of materials that are used inside a hard disc drive.
`These requirements are intended to reduce the emission of
`materials onto the magnetic media or heads during the
`
`The present invention relates generally to a stator assem-
`bly used in a dynamoelectric machine such as a motor or a
`generator. It relates particularly to a spindle motor such as
`used in a hard disc drive, and to the construction and
`arrangement of a stator assembly made from a plurality of 20
`arc segments.
`
`15
`
`BACKGROUND OF THE INVENTION
`
`Computers commonly use disc drives for memory storage
`purposes. Disc drives include a stack of one or more
`magnetic discs that rotate and are accessed using a head or
`read-write transducer. Typically, a high speed motor such as
`a spindle motor is used to rotate the discs.
`In conventional spindle motors, stators have been made
`by laminating together stamped pieces of steel. These
`stamped pieces of steel are generally circular in nature, but
`also have "’poles" extending either inwardly or outwardly,
`depending on whether the rotor is on the inside or surrounds
`the stator. The stamped pieces are laminated together and
`then coated with insulation. Wire is then wound around the
`poles to form stator windings.
`An example of a conventional spindle motor 1 is shown
`in FIG. 1. The motor 1 includes a base 2 which is usually
`made from die cast aluminum, a stator 4, a shaft 6, bearings
`7 and a disc support member 8, also referred to as a hub. A
`magnet 3 and flux return ring 5 are attached to the disc
`support member 8. The stator 4 is separated f~om the base 2
`using an insulator (not shown) and attached to the base 2
`using a glue. Distinct structures are formed in the base 2 and
`the disc support member 8 to accommodate the bearings 7.
`One end of the shaft 6 is inserted into the bearing 7
`positioned in the base 2 and the other end of the shaft 6 is
`placed in the bearing 7 located in the hub 8. A separate
`electrical connector 9 may also be inserted into the base 2.
`Each of these parts must be fixed at predefmed tolerances
`with respect to one another. Accuracy in these tolerances can
`sigtfificantly enhance motor performance.
`In operation, the disc stack is placed upon the hub. The
`stator windings are selectively energized and interact with
`the permanent magnet to cause a defined rotation of the hub.
`As hub 8 rotates, the head engages in reading or writing
`activities based upon instructions from the CPU in the
`computer.
`Manufacturers of disc drives are constantly seeking to
`improve the speed with which data can be accessed. To an
`extent, this speed depends upon the efficiency of the spindle
`motor, as existing magneto-resistive head technology is
`capable of accessing data at a rate greater than the speed
`offered by the highest speed spindle motor currently in
`production. The efficiency of the spindle motor is dependent
`upon the dimensional consistency or tolerances between the
`
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`

`

`Case 1:17-cv-00300-UNA Document 1-2 Filed 03/20/17 Page 12 of 18 PageID #: 46
`US 7,067,952 B2
`
`3
`operation of the drive. Of primary concern are glues used to
`attach components together, varnish used to insulate wire,
`and epoxy used to protect steel laminations from oxidation.
`In addition to such outgassed materials, airborne particu-
`late in a drive may lead to head damage. Also, airborne
`particulates in the disc chive could interfere with signal
`transfer between the read!write head and the media. To
`reduce the effects of potential airborne particulate, hard
`drives are manufactured to exacting clean room standards
`and air filters are installed inside of the drive to reduce the
`contamination levels during operation.
`An example of a spindle motor is shown in U.S. Pat. No.
`5,694,268 (Dunfield et al.) (incorporated herein by refer-
`ence). Referring to FIG. 5 of this patent, a stator of the
`spindle motor is encapsulated with an overmold 42. The
`overmolded stator 40 contains openings through which
`mounting pins 44 may be inserted for attaching the stator
`200 to a base. U.S. Pat. No. 5,672,972 (Viskochil) (incor-
`porated herein by reference) also discloses a spindle motor
`having an overmolded stator. One drawback with the stators
`described in these patents is this difficulty in winding wire
`on the poles. Another drawback is the height of the lami-
`nation stacks. Further, the overmolds shown in these patents
`are not effective in dissipating heat or dampening some
`vibrations generated by energizing the stator windings.
`U.S. Pat. No. 5,806,169 (Trago) (incorporated herein by
`reference) discloses a method of fabricating an injection
`molded motor assembly. However, neither the Trago design
`nor the other prior art designs address the problems of
`winding wire, variation .in the thickness of steel used to
`make the stator cores and the non-uniform grain structure in
`the steel compared to the magnetic flux in the stator during
`operation of the motor.
`Some of these problems have been addressed by motor-
`manufacturing methods in which individual stator arc seg-
`ments are made and wound with wire to form poles, and
`these segments are then assembled to form a complete stator.
`While this process allows for higher packing density, it has
`several drawbacks. Somehow the individual segments have
`to be assembled and held in place to form the stator. In
`addition, the individual wires of the different poles have to
`be connected together for the poles that are of the same
`phase. These numerous wires tend to get in the way during
`the assembly process, slowing down the manufacturing
`process.
`U.S. Pat. No. 6,049,153 to Nishiyama describes the use of
`crimping or welding to attach segments together. This pro-
`cess deforms the steel and reduces the level of magnetic flux
`produced by the laminations. The process also requires
`numerous wire interconnecfions when the poles are wound
`as discrete components, and it does not offer improvements
`in wire routing.
`U.S. Pat. No. 5,729,072 to Hirano describes the use of
`welding or an adhesive to hold the segments together. A
`disadvantage of this approach is that the stator poles must be
`handled as separate elements during stator construction.
`This requires complicated assembly equipment and a slow
`manufactmSng process.
`U.S. Pat. No. 6,265,804 to Nitta describes the use of
`plastic insulation in combination with segmented stators.
`This approach does not improve on the problem of how to
`assemble and hold the individual segments in place, nor does
`it aid in connecting the various wires.
`U.S. Pat. No. 6,167,610 to Nakaham describes a method
`of making a rotary motor where a length of steel strip has
`thin portions between blocks of pole teeth. Wire is wound on
`the pole teeth while the steel strip is straight. Later the thin
`
`4
`sections are bent to allow the poles to form. a stator. One
`problem with this design is that when the thin portions are
`bent, the stress on the steel reduces the flux capacity of the
`connecting steel, forming the back iron. Also, the stamping
`of such a length of steel strip would be expensive and result
`in large amount of scrap. Thus, a need exists for a method
`of making motors overcoming the aforementioned prob-
`lems.
`
`10
`
`BRIEF SUMMARY OF THE INVENTION
`
`30
`
`A method of making stator assemblies has been invented
`which overcomes many of the foregoing problems. In addi-
`tion, unique stator assemblies and other components of a
`15 motor have been invented. In one aspect, the invention is a
`stator assembly comprising a plurality of discrete stator
`segments each at least partially encased with a phase change
`material, wherein the phase change ma.terial also comprises
`a bridge between adjacent segments to link adjacent seg-
`20 ments into a continuous strip; and the linked stator segments
`being arranged and secured together to form the stator
`assembly.
`In a second aspect, the invention is a combination of stator
`arc segments and a flexible carrier used to link said stator a)rc
`25 segments during a winding operation comprising: a) a
`plurality of stator arc segments; and b) a phase change
`material constituting said flexible carder adhered to the
`stator arc segments which links said segments in a uniform
`and predetermined position with respect to one another.
`In another aspect the invention is a method of making a
`stator assembly comprising: a) providing at least two stator
`arc segments linked together by a phase change material and
`each constituting a pole and having a first side surface and
`35 a second side surface; b) winding wire on the poles; c)
`aligning said stator arc segments to form a toroidal core,
`wherein each said side surface of one segment is in contact
`with an opposing side surface of another segment; and d)
`substantially encapsulating said toroidal core with a mono-
`lithic body of phase change material to form said stator
`assembly.
`In another aspect the invention is a method of making a
`stator assembly comprising: a) providing at least two stator
`arc segments linked together by a phase change material and
`45 each providing a pole and having a first side surface and a
`second side surface; b) winding wire on each pole of each
`arc segment; c) aligning said stator arc segments to form a
`toroidal core, wherein each said side surface of one segment
`is in contact with an opposing side surface of another
`50 segment; and d) placing a retaining member on the exterior
`of the toroidal core to unitize the structure.
`In yet another aspect, the invention is a series of discrete
`stator segments each substantially encapsulated with, and
`linked together by bridges made from, an injection molded
`55 thermoplastic material.
`With the unique linked but discrete segment assemblies,
`wire can be wound around the poles with a high packing
`density, yet at the same time the segments can be maintained
`in their proper order so that one continuous piece of wire can
`6o be used to wind all poles in the same series or phase, making
`it unnecessary to later connect wires from individual wind-
`ings to one another. The invention provides the foregoing
`and other features, and the advantages of the invention will
`become further apparent from the following detailed
`65 description of the presently preferred embodiments, read in
`conjunction with the accompanying drawings. The detailed
`description and drawings are merely illustrative of the
`
`40
`
`Copy provided by USPTO from the PIRS Image Database on 0912812016
`
`..............
`
`

`

`Case 1:17-cv-00300-UNA Document 1-2 Filed 03/20/17 Page 13 of 18 PageID #: 47
`
`US 7,067,952 B2
`
`5
`invention and do not limit the scope of the invention, which
`is defined by the appended claims and equivalents thereof.
`
`BRIEF DESCRIPTION OF SEVERAL VIEWS OF
`THE DRAWINGS
`
`FIG. 1 is an exploded, partial cross-sectional and perspec-
`tive view of a conventional prior art high speed motor.
`FIG. 2 is perspective view of a stator arc segment being
`loaded into an injection mold prior to injecting a phase !0
`change material to make a limited series of stator arc
`segments of the present invention.
`FIG. 3 is a perspective, partial cross-sectional view of an
`encapsulated stator arc segment of FIG. 2.
`FIG. 4 is a perspective view of the encapsulated stator arc !5
`segment of FIG. 2.
`FIG. 5 is a perspective view of a series of encapsulated
`stator arc segments of FIGS. 2-4 linked together by a
`thermoplastic webbing.
`FIG. 6 is a perspective view of the series of stator arc 20
`segments of FIG. 5 during wire winding.
`FIG. 7 is a perspective view of an injection molded stator
`assembly using the linked serial of webbed stator arc seg-
`ments of FIG. 6.
`FIG. 8a is a cross-sectional view of a toroidal core made z5
`from the linked seres of stator arc segments after the wire
`winding shown in FIG. 5 in an injection mold assembly,
`prior to injecting a phase change material.
`FIG. 8b is a cross-sectional view of the toroidal core of
`FIG. 8a in an injection mold assembly after injecting a phase 30
`change material, resulting in the stator assembly of FIG. 7.
`FIG. 9 is an exploded, partial cross-sectional and perspec-
`tive view of a motor using the encapsulated webbed stator of
`FIG. 7.
`FIG. 10 is a perspective view of a stator assembly of a 35
`second embodiment of the present invention using a steel
`band to unitize the webbed stator arc segments.
`
`6
`ing inwardly. The stamped pieces are then coated with
`encapsulating material 22 which provides electrical insula-
`tion and laminates the pieces together to form a stator arc
`segment 20, and links other arc segments into a continuous
`strip via webbing 23.
`The encapsulating material 22 is preferably formed of a
`phase change material, meaning a material that can be used
`in a liquid phase to envelope the stator, but which later
`changes to a solid phase. There are two types of phase
`change materials that will be most useful in practicing the
`invention: temperature activated and chemically activated. A
`temperature activated phase change material will become
`molten at a higher temperature, and then solidify at a lower
`temperature. However, in order to be practical, the phase
`change material must be molten at a temperature that is low
`enough that it can be used to encapsulate a toroidal core.
`Preferred phase change materials will be changed from a
`liquid to a solid in the range of about 200° F. to about 700°
`F., more preferably in the range of about 550° F. to about
`650° F. The most preferred temperature activated phase
`change materials are thermoplastics. The preferred thermo-
`plastic will become molten at a temperature at which it is
`injection-moldable, and then will be solid at norn~al oper-
`ating temperatures for the motor. An example of a phase
`change material that changes phases due to a chemical
`reaction, and which could be used to form the body, is an
`epoxy. Other suitable phase change materials may be clas-
`sifted as thermosetting materials.
`As shown in FIG. 2 the segments 20 can be placed in a
`multi-cavity mold 28 to increase productivity. In the pre-
`ferred embodiment the individual laminations 11 making up
`the segments are not interconnected but loosely stacked
`together before insertion into the mold 28. After the ther-
`moplastic solidifies, the overmolded segments are ejected
`from their cavities. New laminations are inserted into the
`cavities and the process repeats. In the preferred embodi-
`ment, a continuous strip of segments is formed by linking
`the webbing from successive molding operation. This is
`done by designing the tool to insert a section of the plastic
`webbing of the outermost segment molded in the prior cycle
`with the new laminations to be molded. When the plastic
`encapsulates the new segments it can mechanically lock
`with or, depending upon design, re-melt, the webbing from
`the prior cycle, thus making a continuous strip, as shown in
`FIG. 5. The series has segments 20 with poles 21A, 21B and
`21C arranged next to one another as they will be in the
`finished stator assembly.
`The stator arc segments 20 are preferably molded into a
`continuous strip where the webbing acts as a carrier to link
`the segments together. In the preferred embodiment the
`encapsulating material 22 forms wire retaining flanges 24 to
`prevent wire from slipping off the pole. In a preferred
`embodiment, winding posts 25 as well as webbing 23 allow
`orientation of wire as it transfers across multiple poles.
`By precisely aligning the stator arc segments 20, the
`webbing 23 can also be used to guide the wire between
`common phase poles, thus eliminating the need for inter-
`connections commonly used on segmented stator motors.
`This greatly enhances the efficiency for winding wire 15
`around the poles 21 and significantly reduces the cost.
`The webbing can be deflected to allow the gap between
`adjoining poles to be increased as is shown in FIG. 6. This
`allows wire 15 to be wound around the poles 21 of the stator
`arc segments 20 using a fly winder 34 that has a set of
`needles 35. The wire 15 is wound around one pole 21 and is
`then wound around another pole 21 in its phase until all
`poles 21 in the same phase are wound with the same wire 15.
`
`DETAILED DESCRIPTION OF THE DRAWINGS
`AND PREFERRED EMBODIMENTS OF THE
`INVENTION
`
`40
`
`A preferred embodiment of a motor of the present inven-
`tion and portions of the motor at different stages of manu-
`facture are shown in FIGS. 2-7 and 9. The spindle motor 45
`100 (FIG. 9) is designed for rotating a disc or stack of discs
`in a computer hard drive. Motor 100 is formed by using an
`injection molded stator assembly 40, that is formed by
`injection molding a plurality of stator arc segments 20 (FIG.
`2) aligned to form a toroidal core 17 (FIG. 7). Although the 50
`embodiment described here uses individual arc segments,
`one of ordinary skill in the art will understand that groups of
`two, three or any greater number of arc segments may be
`used. The preferred motor of the present invention may be
`smaller, has a grain structure that is more uniformly aligned, 55
`and allows for greater packing density of wire and reduces
`waste of steel in the manufacturing process, as compared
`with conventional motors, thereby increasing power and
`reducing stack up tolerances and manufacturing costs and
`producing other advantages discussed below.
`Referring to FIG. 2, a stator arc segment 20 is first
`constructed, using steel laminations 11. The stator arc seg-
`ment 20 is made of steel pieces that are stamped out of rolled
`steel. The stamped steel pieces are arc segments, but also
`have a pole 21 extending inwardly or outwardly depending 65
`on whether the rotor is inside or surrounds the stator. In the
`embodime