GU/2UA“S°N6PpOTr
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`i!" mailing label number EL669269646US.
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`2 OoooS9awo =aS°> No
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`3-25 -<}
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`Case No. 8864/20
`
`To the Commissionerfor Patents:
`
`PATENT APPLICATION TRANSMITTAL LETTER
`
`Transmitted herewith forfiling is the patent application of: Griffith D. Nea! for : STATOR ASSEMBLY MADE FROM A PLURALITY OF
`
`TOROIDAL CORE ARC SEGMENTS ANDMOTOR USING SAME. Enclosedare:
`
`Six(6) sheet(s) of drawings, twenty-four (24) pagesof application (including title page), and the following Appendices :_
`
`PTO
`5.
`
`JC996U
`
`03/02/01
`
`
`09/7961ANGCAEA
`|29-20|9
`
`
`
`Declaration.
`
`Powerof Attomey.
`
`Verified statement to establish small entity status under 37 CFR §§ 1.9 and 1.27.
`
`Assignmenttransmittal letter and Assignmentof the invention to : Encap Motor Corporation.
`
`Ckims as Filed
`Col. 14
`Col, 2
`
`
`Mditiple Dependent Claims Present
`*}Ahe difference in col. 1 is less than zero,
`enter "0"in col. 2.
`
`
`
`
`Please charge my Deposit Account No. 23-1925 in the amount of$:
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`. A duplicate copy of this sheet is enclosed.
`
`A checkin the amountof $: 516 to coverthe filing fee is enclosed.
`
`<i
`sigs
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`oO
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`The Commissioneris hereby authorized to charge paymentof the following fees associated with this communication or credit
`any overpayment to Deposit Account No. 23-1925. A duplicate copy of this sheet is enclosed.
`
`Any additionalfiling fees required under 37 CFR § 1.16.
`iS
`Anypatent application processing fees under 37 CFR §1.17.
`El
`The Commissioneris hereby authorized to charge paymentof the following fees during the pendencyofthis application or
`credit any overpayment to Deposit Account No. 23-1925. A duplicate copyof this sheet is enclosed.
`
`oO
`CO
`CI
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`Any filing fees under 37 CFR § 1.16 for presentation of extra claims.
`Any patent application processing fees under 37 CFR § 1.17.
`The issue fee set in 37 CFR § 1.18 at or before mailing of the Notice of Allowance, pursuant to 37 CFR § 1.311(b).
`
`SlAlo |
`
`Date
`
`alled
`
`Sailesh K. Patel
`BRINKS HOFER GILSON & LIONE
`Registration No. 46,982
`
`Rev. Nov-98
`FACOMMON\SPatel\8864-20 Patent App Trans Ltr.doc
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`Am. Hondav. IV II - IPR2018-00619
`PETHONDA_1011-0001
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`Am. Honda v. IV II - IPR2018-00619
`PET_HONDA_1011-0001
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`“Express Mail" mailing label number
`
`Date ofDeposit:
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`
`
`
`
`Our Case No. 8864/20
`
`IN THE UNITED STATES PATENT AND TRADEMARK OFFICE
`APPLICATION FOR UNITED STATES LETTERS PATENT
`
`INVENTOR:
`
`GRIFFITH D. NEAL
`
`TITLE:
`
`ATTORNEYS:
`
`STATOR ASSEMBLY MADE FROM A
`PLURALITY OF TOROIDAL CORE
`ARC SEGMENTS AND MOTOR
`USING SAME
`
`STEVEN P. SHURTZ
`REG. NO. 31,424
`SAILESH K. PATEL
`REG. NO. 46,982
`BRINKS HOFER GILSON & LIONE
`P.O. BOX 10395
`CHICAGO, ILLINOIS 60610
`(312) 321-4200
`
`Am. Hondav. IV II - IPR2018-00619
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`-41-
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`STATOR ASSEMBLY MADE FROM A PLURALITY OF TOROIDAL
`CORE SEGMENTS AND MOTOR USING SAME
`
`FIELD OF THE INVENTION
`
`The present invention relates generally to a stator assembly used ina
`
`motor.
`
`It relates particularly to a spindle motor such as usedin a hard disc
`
`drive, and to the construction and arrangementof a stator assembly made
`
`from a plurality of arc segments.
`
`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 bylaminating
`
`together stamped pieces of steel. These stampedpieces of steel are
`
`generally circular in nature, but also have “poles” extending either inwardly or
`
`outwardly, depending on whetherthe 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
`
`motor1 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 andflux return ring 5 are attached to the disc support
`
`member8. The stator 4 is separated from 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 endofthe 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
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`in the hub 8. A separate electrical connector 9 may also be inserted into the
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`base 2.
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`Each of these parts mustbe fixed at predefined tolerances with respect
`
`to one another. Accuracyin these tolerances can significantly enhance motor
`
`performance.
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`In operation, the disc stack is placed upon the hub. The stator
`
`windings are selectively energized and interact with the permanent magnetto
`
`cause a defined rotation of the hub. As hub 8 rotates, the head engages in
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`reading or writing activities based upon instructions from the CPUin the
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`computer.
`
`Manufacturers of disc drives are constantly seeking to improve the
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`speed with which data can be accessed. To an extent, this speed depends
`
`uponthe efficiency of the spindle motor, as existing magneto-resistive head
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`technology is capable of accessing data at a rate greater than the speed
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`offered by the highest speed spindle motor currently in production. The
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`efficiency of the spindle motor is dependent upon the dimensional consistency
`
`or tolerances between the various components of the motor. Greater
`
`dimensional consistency between componentsleads to a smaller gap
`
`betweenthe stator 4 and the magnet 3, producing more force, which provides
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`more torque and enablesfaster acceleration and 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 circular stamped pieces of steel, the grain
`
`orientation at different points around the circle differs. Compared from the
`
`radiusline of the circle, the grain orientation is sometimes aligned along the
`
`radius, sometimes transverseto 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 asit rotates.
`
`Another drawbackwith using circular steel] pieces is that, especially for
`
`inward facing poles, it has been difficult to wind the wire windingstightly
`
`because of the cramped space to workinside of the laminated stator core.
`
`The cramped working space creates a lowerlimit on the size of the stator and
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`-3-
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`thus the motor. The limited working space also results in 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 powerand thustheefficiency of the spindle motor.
`An important factor in motor design is to reduce stack up tolerancesin
`the motor. Stack up tolerances reduce the overall dimensional consistency
`between the components. Stack up tolerancesrefer to the sum of the
`variation ofall the tolerancesofall the parts, as well as the overall tolerance
`that relates to the alignmentof the parts relative to one another. One source
`of stack up tolerancesis from thecircular stator body. Generally, the
`thicknessofrolled steel is not uniform across the widthofthe roll. Sometimes
`the edgesare thicker or thinner than the center.
`In a stator made from
`circular stamped pieces, the thicknessofindividual laminations are thus
`different from one side to the other. When stacked together, this creates a
`stack up tolerance problem. Furthermore,thecircular stampingsleavealot of
`wasted steel that is removed and must be recycled or discarded.
`Anotherimportant factor in motor design is the lowering of the
`operating temperature of the motor. Increased motor temperature affects the
`electrical efficiency of the motor and bearinglife. As temperature increases,
`resistive loses in wire increase, thereby reducing total motor power.
`Furthermore, 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 maydeflect,
`causing non-uniform rotation reducing bearing life. This non-uniform rotation
`causesa further problem oflimiting the ability of the servo system controlling
`the read/write headsto follow data tracks on the magnetic media. One
`drawbackwith existing motor designsis their limited effective dissipation of
`In
`the heat, and difficulty in incorporating heat sinks to aid in heat dissipation.
`addition, in current motors the operating temperatures generally increase as
`the size of the motor is decreased.
`
`
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`-4-
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`Manufacturers have established strict requirements on the 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
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`heads during the 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 particulate in a drive
`
`may lead to head damage. Also, airborne particulates in the disc drive could
`
`interfere with signal transfer between the read/write head and the media. To
`
`reducethe effects of potential airborne particulate, hard drives are
`
`manufactured to exacting clean room standards andair filters are installed
`
`inside of the drive to reduce the contamination levels during operation.
`
`An example of a spindle motor is shownin U.S. Patent No. 5,694,268
`
`(Dunfield ef a/.) (incorporated herein by reference). 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
`
`maybe inserted for attaching the stator 200 to a base. U.S. Patent
`
`No. 5,672,972 (Viskochil) (incorporated herein by reference) also discloses a
`
`spindle motor having an overmolded stator. One drawback with the overmold
`
`used in these patentsis that it has a different coefficient of linear thermal
`
`expansion (“CLTE”) than the corresponding metal parts to whichit is attached.
`
`Another drawbackwith the overmoid is that it is not very effective at
`
`dissipating heat. Further, the overmolds shownin these patents are not
`
`effective in dampening some vibrations generated by energizing the stator
`
`windings.
`
`U.S. Patent No. 5,806,169 (Trago) (incorporated herein by reference)
`
`discloses a method of fabricating an injection molded motor assembly.
`
`However, the motor disclosed in Tragois a step motor, not a high speed
`
`spindle motor, and would not be used in applications such as hard discdrives.
`
`Further, none of these three prior art designs address the problem ofvariation
`
`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
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`-5-
`
`operation of the motor. Thus, a need exists for an improved high speed
`spindle motor, having properties that will be especially useful in a hard disc
`drive, overcoming the aforementioned problems.
`
`BRIEF SUMMARY OF THE INVENTION
`
`A high speed motor has beeninvented which overcomes many of the
`foregoing problems.
`In addition, unique stator assemblies and other
`components of a high speed motor have been invented, as well as methodsof
`manufacturing motors and hard disc drives.
`In one aspect, the invention is a
`motor comprising: a plurality of stator arc segments forming a toroidal core,
`wherein each said stator arc segment has two end surfaces that are eachin
`contact with an end surface of another stator arc segmentto form a toroidal
`core; and a monolithic body of phase change material substantially
`encapsulating the stator arc segments and holding said toroidal core in place.
`
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`
`
`In another aspectthe invention is a method of making a motor
`comprising: providing at least two stator arc segments each havingafirst end
`surface and a second end surface; aligning said stator arc segments to form a
`toroidal core, wherein each said end surface of one segmentis in contact with
`an opposing end surface of another segment; and substantially encapsulating
`said toroidal core with a monolithic body of phase change material and
`solidifying the phase change materialto hold the stator arc segments
`together.
`
`In another aspectthe invention is a method of making a motor
`comprising: providing four stator arc segments, wherein each stator arc
`segmenthasafirst end surface and a second end surface;aligning said
`stator arc segments to form a toroidal core, wherein each said end surface of
`one segmentis in contact with an opposing end surface of another segment;
`and substantially encapsulating said toroidal core with a monolithic body of
`phase change material, wherein said substantially encapsulating is by
`injection molding said phase change material around said toroidal core.
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`-6-
`
`in yet another aspect, the inventionis a combination of stator arc
`segments and a carrier used to support said stator arc segments during a
`winding operation comprising a plurality of stator arc segments,and: a
`plurality of cavities to hold and support said stator arc segments, wherein said
`cavities are spaced apart a distance X, wherein the distance X is the length of
`uncoiled wire necessary to align said stator arc segments to form a toroidal
`
`core.
`
`The invention provides the foregoing and other features, and the
`advantagesof the invention will become further apparent from the following
`detailed description of the presently preferred embodiments, read in conjunction
`with the accompanying drawings. The detailed description and drawings are
`merelyillustrative of the invention and do notlimit 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 perspective view of a
`conventional high speed motorof the present invention.
`FIG. 2 is a perspective view of a stator arc segment.
`FIG. 3 is a perspective view of a combined carrier assembly and stator
`arc segments of FIG. 2.
`FIG. 4 is a perspective view of stator arc segments of FIG. 2 with
`windings thereon ready to be formedinto a toroidal core.
`FIG. 5 is a perspective view of an injection molded stator assembly
`using the stator arc segments of FIG. 4.
`FIG. 6a is a cross-sectional view of the toroidal core of FIG. 4 in an
`injection mold assembly,prior to injecting a phase change material.
`FIG. 6b is a cross-sectional view of the toroidal core of FIG. 4 in an
`injection mold assembly,after injecting a phase change material.
`FIG. 7 is an exploded, partial cross-sectional and perspective view ofa
`high speed motor using the encapsulated stator of FIG. 5.
`FIG. 8 is an exploded, partial cross-sectional and perspective view of a
`high speed motor and disc assembly madewith the motor of FIG. 7.
`
`
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`-7-
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`FIG. 9 is a cross-sectional view of the motor of FIG. 8.
`
`DETAILED DESCRIPTION OF THE DRAWINGS AND PREFERRED
`EMBODIMENTS OF THE INVENTION
`
`
`
`A preferred embodiment of a high speed motor of the present invention
`and portions of the motorat different stages of manufacture are shownin
`FIGS. 2-7 and 9. By “high speed”it is meant that the motor can operate at
`over 5,000 rpm. The spindle motor 100 is designed for rotating a disc or stack
`of discs in a computerhard 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 aligned to form a toroidal core 17. Although the
`embodiment described here uses four arc segments, one of ordinary skill in
`the art will understand that two, three or any greater numberof arc segments
`may be used. Thepreferred motorof the present invention is smaller, has a
`grain structure that is more uniformly aligned, allows for greater packing
`density of wire and reduces waste of steel in the manufacturing process as
`compared with conventional motors used fordiscdrives, thereby increasing
`powerand reducing stack up tolerances and manufacturing costs and
`producing other advantages discussed below.
`Referring to FIG. 2, a stator arc segment20is first constructed, using
`steel laminations 11. The stator arc segment 20 is madeof steel pieces that
`are stamped outofrolled steel. The stamped steel pieces are arc segments,
`but also have poles 21 extending inwardly or outwardly depending on whether
`the rotor is inside or surroundsthe stator.
`In the embodiment shownin
`FIG. 2, the poles 21 are shown extending inwardly. The stamped pieces are
`then coated with epoxy which provides insulation and laminates the pieces
`togetherto form a stator arc segment20.
`As shownin FIG. 3, the stator arc segments 20 are then preferably
`placedin a carrier 30. The carrier 30 hasaplurality of cavities 32 that hold
`the stator arc segments 20 in place.
`In a preferred embodiment, the space
`betweenthe cavities is equivalent to the length of wire neededto travel from a
`point on one pole 21a to the next pole 21b in the same phaseof windings
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`
`-8-
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`following the arc of the stator arc segments 20. The carrier 30 shownin FIG.
`
`3 showsan alternative embodiment where the space between the cavities is
`
`not necessarily equivalent to the length of wire needed to travel from a point
`
`on one pole 21a to the next pole 21b. By precisely aligning the stator arc
`
`segments 20, the carrier 30 greatly enhancesthe efficiency for winding wire
`
`15 around the poles 21 and manufacturing stators.
`
`Wire 15 is then wound around the poles 21 of the stator arc segments
`
`20 using a spool winder 34 that has a set of needles 35 that wind wire around
`
`the poles 21. 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
`
`the arc segments 20 in the carrier 30 makesit much easier for needle 35 to
`
`wind wire 15 around poles 21. Using this method, a wire packing density of
`about 60 percent to about 80 percent can be achieved.
`
`As shownin FIG. 4, the stator arc segments 20 are then removed from
`
`the carrier and aligned to form a magnetically inducible toroidal core 17
`
`having a plurality of poles 21 thereon, and wire windings 15 which serve as
`
`conductors. To form the toroidal core 17, an end surface 16 of each stator arc
`
`segment20is aligned and broughtinto contact with a corresponding end
`surface 19 of another stator arc segment 20. The wire 15 between the poles
`21 of different stator arc segments 20is also alignedin the toroidal core 17,
`
`following the arc of the stator arc segments 20. As a result, the wire in the
`
`toroidal core 17 is taught. After the wire is wound so that one set of three
`
`leads is terminated together to create the commonground46, and the other
`endsof the wire, are for each of the three phases form the leads 47a, 47b and
`
`47c by which currentis supplied to the windings. The conductors induce or
`
`otherwisecreate a plurality of magnetic fields in the core when electrical
`
`current is conducted through the conductors.
`field is induced in each ofthe poles 21.
`As shownin FIG.5, the toroidal core 17 is then encapsulated in a body
`42. Togetherthe toroidal core 17 and the body 42 make up an injection
`
`In this embodiment, a magnetic
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`woundwith the same wire 15. Poles 21 in other phases are also similarly
`wound. Having only arc segments, rather thanafull toroidal core, and placing
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`-9-
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`molded stator assembly 40. The body 42 is preferably a monolithic body.
`Monolithic is defined as being formed as a single piece. The body 42
`substantially encapsulates the toroidal core 17. Substantial encapsulation
`meansthat the body 42 either entirely surrounds the toroidal core 17, or
`
`surrounds almostall of it except for minor areas of the toroidal core 17 that
`
`may be exposed. However, substantial encapsulation meansthat the body
`42 andtoroidal core 17 arerigidly fixed together, and behave asa single
`componentwith respect to harmonic oscillation vibration.
`
`The body 42 is preferably formed of a phase change material, meaning
`a material that can be usedin a liquid phase to envelope the stator, but which
`later changesto 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 thatit can be
`used to encapsulate a toroidal core. Preferred phase change materials will be
`changedfromaliquid 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
`
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`preferred temperature activated phase change materials are thermoplastics.
`The preferred thermoplastic will become molten at a temperature at whichit is
`injection-moldable, and then will be solid at normal operating 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 classified as
`thermosetting materials.
`
`The preferred method of developing the monolithic body 42 comprises
`designing a phase change material to have a coefficient oflinear thermal
`
`expansion suchthat the phase change material contracts and expands at
`approximately the same rate as the metal laminations of the toroidal core 17.
`
`For example, the preferred phase change material should have a CLTE of
`between 70% and 130% of the CLTE of the core of the stator. The phase
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`-10-
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`change material should have a CLTEthatis intermediate the maximum and
`minimum CLTE of the toroidal core and other motor components where the
`
`bodyis in contact with those other components and they are made of a
`different material than the core. Also, the CLTE’s of the body and toroidal
`
`core should match throughout the temperature range of the motorduringits
`
`operation. An advantage of this method is that a more accurate tolerance
`
`may be achieved between the body and the components ofthe toroidal core
`because the CLTE of the body matches the CLTE ofthe toroidal core
`
`components more closely. Most often the toroidal core componentswill be
`metal, and most frequently steel and copper. Other motor parts are often
`
`made of aluminum and steel.
`
`Most thermoplastic materials have a relatively high CLTE. Some
`
`thermoplastic materials may have a CLTE at low temperatures that is similar
`
`to the CLTE of metal. However, at higher temperatures the CLTE does not
`
`match that of the metal. A preferred thermoplastic material will have a CLTE
`of less than 2 x 10°in/in/°F, more preferably less than 1.5 x 10°in/in/°F,
`throughout the expected operating temperature of the motor, and preferably
`
`throughout the range of 0-250°F. Most preferably, the CLTE will be between
`about 0.8 x 10° in/in/°F and about 1.2 x 10° in/in/°F throughout the range of
`0-250°F. (When the measured CLTE of a material depends onthe direction
`
`of measurement, the relevant CLTE for purposesof defining the present
`
`invention is the CLTEin the direction in which the CLTEis lowest.)
`
`The CLTE of common solid parts used in a motor are as follows:
`
`Steel
`
`Aluminum
`
`Ceramic
`
`23°C
`0.5
`
`0.8
`
`0.3
`
`(x10°in/in/°F)
`
`250°F
`0.8
`
`1.4
`
`0.4
`
`Of course, if the motor is designed with two or moredifferent solids,
`
`such as steel and aluminum components, the CLTE of the phase change
`
`material would preferably be one that was intermediate, the maximum CLTE
`and the minimum CLTEofthe different solids, such as 0.65 infin/°F at room
`temperature and 1.1 x10in/in/°F at 250°F.
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`PET_HONDA_1011-0012
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`Onepreferred thermoplastic material, Konduit OTF-212-11, was made
`into a thermoplastic body and testedforits coefficient of linear thermal
`expansion by a standard ASTM test method.
`It was found to have a CLTEin
`the range of —30 to 30°C of 1.09x10°in/in/°F in the X direction and 1.26x10°
`in/in/°F in both the Y and Z directions, and a CLTE in the range of 100 to
`240°C of 1.28x10°in/in/°F in the X direction and 3.16x10°in/in/°F in both the
`
`Y and Z directions. (Hence, the relevant CLTEsfor purposes of defining the
`invention are 1.09 x 10° in/in/°F and 1.28 x 10° in/in/°F.) Another similar
`material, Konduit PDX —0-988, was found to have a CLTE in the range of —30
`to 30°C of 1.1x10°in/in/°F in the X direction and 1.46x10°in/in/°F in both the
`Y and Z directions, and a CLTEin the range of 100 to 240°Cof 1.16x10°
`in/in/°F in the X direction and 3.4x10°in/in/°F in both the Y and Z directions.
`
`By contrast, a PBS type polymer, (Fortron 4665) waslikewise tested. While it
`had a low CLTEin the range of —30 to 30°C (1.05x10°in/in/°F in the X
`direction and 1.33x10°in/in/°F in both the Y and Z directions), it had a much
`higher CLTEin the range of 100 to 240°C (1.94x10°in/in/°F in the X direction
`and 4.17x10°in/in/°F in both the Y and Z directions).
`
`In addition to having a desirable CLTE, the preferred phase change
`
`material will also have a high thermal conductivity. A preferred thermoplastic
`
`material will have a thermal conductivity of at least 0.7 watts/meter°K using
`
`ASTM test procedure 0149 and tested at room temperature (23°C).
`
`Stator assemblies made from arc segments held together by a body of
`phase change material partially encapsulating the stator are themselves novel
`
`and define another aspect of the present invention.
`
`In the present embodiment, the phase change material used to make
`the body 42 is preferably a thermally conductive but non-electrically
`conductive plastic.
`In addition, the plastic preferably includes ceramicfiller
`particles that enhancethe thermal conductivity, while reducing the coefficient
`of linear thermal expansion of the plastic. A preferred form of plastic is
`polyphenyl sulfide (PPS) sold underthe tradename “Konduit” by LNP. Grade
`OTF-212 PPSis particularly preferred. Examples of other suitable
`
`thermoplastic resins include, but are notlimited to, thermoplastic resins such
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`Am. Hondav. IV II - IPR2018-00619
`PETHONDA_1011-0013
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`Am. Honda v. IV II - IPR2018-00619
`PET_HONDA_1011-0013
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`as 6,6-polyamide, 6-polyamide, 4,6-polyamide, 12,12-polyamide,
`6,12-polyamide, and polyamides containing aromatic monomers, polybutylene
`terephthalate, polyethylene terephthalate, polyethylene napththalate,
`polybutylene napththalate, aromatic polyesters, liquid crystal polymers,
`polycyclohexane dimethylol terephthalate, copolyetheresters, polyphenylene
`sulfide, polyacylics, polypropylene, polyethylene, polyacetals,
`polymethylpentene, polyetherimides, polycarbonate, polysulfone,
`polyethersulfone, polyphenylene oxide, polystyrene, styrene copolymer,
`mixtures and graft copolymers of styrene and rubber, and glass reinforced or
`impact modified versions of such resins. Blends of these resins such as
`polyphenylene oxide and polyamide blends, and polycarbonate and
`polybutylene terephthalate, may also be used in this invention.
`As shownin FIG. 6a, to encapsulate the toroidal core 17 and form body
`
`42, the toroidal core 17 is first clamped and held in place by pins 61 in an
`injection mold cavity 66. The injection mold cavity 66 is very effective and
`maintains the toroidal shape of the toroidal core 17. Molten phase-change
`material is then injected into the molding cavity 66 with an extrusion screw
`(not shown) until the pressure inside the cavity reaches a predetermined
`molding pressure. After injecting the molten phase change material, the pins
`61 retract as shown in FIG. 6b. The phase change material is then allowed to
`cool and solidify into a monolithic body 42 that substantially encapsulates the
`toroidal core 17. The preferred thickness of the body 42 depends on the
`
`aspect ratio of the toroidal core 17.
`The injection molded stator assembly 40 is then used to construct the
`rest of the spindle motor 100 (FIG. 7). The spindle motor 100 includes a hub
`108, which serves as a disc support member, the stator assembly 40, a base
`
`102, a shaft 106 and bearings 107.
`
`As shownin FIG. 7, a shaft 106 is connected to the hub or disc support
`
`member 108 and is surrounded by bearings 107, which are adjacent against
`the base 102 of the motor. A rotor or magnet 103is fixed to the inside of the
`
`hub 108 on a flange so as to be in operable proximity to the stator assembly.
`The magnet 103 is preferably a permanent magnet, as described below.
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`PETHONDA_1011-0014
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`Am. Honda v. IV II - IPR2018-00619
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`Referring to FIG. 7, the bearings 107 include an upper bearing 46 and
`a lower bearing 48. Also, each bearing 107 has an outer surface 50 and an
`inner surface 52. The outer surface 50 of the upper bearing contacts the hub
`408 and the outer surface 50 of the lower bearing 48 contacts the lower
`support base 102. The inner surfaces 52 of the bearings 107 contact the
`shaft 116. The bearings are preferably annular shaped. The inner
`surfaces 52 of the bearings 107 maybepressfit onto the shaft 16. A glue
`may also be used. The outer surface 50 of the bearings 107 maybepressfit
`into the interior portion of the base 102. A glue may also be used. The
`bearings in the embodiment shownin FIG. 7 are ball bearings. Alternatively
`other types of bearings, such as hydrodynamic or combinationsof
`hydrodynamic and magnetic bearings, may be used. The bearings are
`typically madeofstainlesssteel.
`The shaft 106 is concentrically disposed within the interior portion of
`the stator assembly 40 and the base 102. The bearings 107 surround
`portions of the shaft 106. As described above,the inner surfaces 52 of the
`bearings are in contact with the shaft 106. The shaft 106 includes a top
`portion 54 and a bottom portion 56. The top portion 54 of the shaft 106is
`fixed to the hub 108. The bottom portion 54 of the shaft 106 is free to rotate
`inside the lower bearing. Thus, in this embodiment, the shaft 106 is freely
`rotatable relative to the base 102. The shaft 106 is preferably cylindrical
`shaped. The shaft 106 may be madeofstainlesssteel.
`Referring to FIGS. 7 and 9, the hub 108 is concentrically disposed
`around the stator assembly 40 and the base 102. The hub 108isfixed to the
`shaft 106 and is spaced apart from the stator assembly 40 and the base 102.
`The hub 108 includesa flux return ring 58 and the magnet 103. The flux
`return ring 58 is glued to the disc support member. The magnet 103 is glued
`to the hub 108. As shownin FIG. 7, the magnet 103 concentrically surrounds
`the stator assembly 40.
`In this embodiment the magnet 103 and stator
`assembly 40 are generally coplanar when the motor 100is assembled.
`The magnet 103 is preferably a sintered part and is one solid piece.
`The magnet 103 is placed in a magnetizer which puts a plurality of discrete
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`PETHONDA_1011-0015
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`Am. Honda v. IV II - IPR2018-00619
`PET_HONDA_1011-0015
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