`
`SS
`
`
`
`¢0/$0/¢0
`
` UL
`
`
`Steven P. Shurtz
`312 323 4230 ©
`E-mail SPShurtz@brinkshofer.com
`
`BRINKS
`
`HOFER
`GILSON
`&LIONE
`
`A PROFESSIONAL CORPORATION
`INTELLECTUAL Property ATTORNEYS
`
`NBC Tower - Suite 3600
`455 N. Crrveront Ptaza Drive
`Cnicaco, Itinois 60611-5599
`brinkshofer.com
`Fax 312-321-4299
`TELEPHONE 372-321-4200
`
`San Jose, CA
`InDIANAPOLIS, IN
`Ann Agsor, MI
`ARLINGTON, VA
`
`o =
`e
`==
`a=a—
`‘ca Zo
`
`tS0
`o- =O
`a =
`
`“Express Mail” mailing label number ELS94 257 797 US
`
`Date of Deposit March 5, 2003
`
`¢
`
`March5, 2003
`
`Attn: Box Patent Application
`Commissioner for Patents
`Washington, D.C. 20231
`
`Re:
`
`STATOR ASSEMBLY MADE FROM A
`MOLDED WEB OF CORE SEGMENTS
`AND MOTOR USING SAME
`Our Case No. 8864/33
`
`Dear Sir:
`
`Enclosedis a specification, including claims and drawings, for a patent application,filed via
`“Express Mail Post Office to Addressee” service to obtain a filing date pursuant to 37 C.F.R.
`§§ 1.10 and 1.53(b). The declaration andfiling fee are not included at the present time.
`
`Sincerely,
`
`Lbien Y. hhong
`
`Steven P. Shurtz
`Reg. No. 31,424
`
`SPS:sr
`Enclosures
`
`
`
`Petitioners Exhibit 1002
`Page 1
`
`Petitioners Exhibit 1002
`Page1
`
`Petitioners Exhibit 1002
`
`
`Page 1
`
`
`
`
`
`“Express Mail" mailing label number
`
`EL 594 257 797 US
`
`Date of Deposit:
`
`March 5, 2003
`
`Our Case No. 8864/33
`
`IN THE UNITED STATES PATENT AND TRADEMARKOFFICE
`APPLICATION FOR UNITED STATES LETTERS PATENT
`
`INVENTOR:
`
`GRIFFITH D. NEAL
`
`TITLE:
`
`ATTORNEYS:
`
`STATOR ASSEMBLY MADE FROM A
`MOLDED WEB OF CORE
`SEGMENTS AND MOTOR USING
`SAME
`
`STEVEN P. SHURTZ
`REG. NO. 31,424
`BRINKS HOFER GILSON & LIONE
`P.O. BOX 10395
`CHICAGO, ILLINOIS 60610
`(312) 321-4200
`
`Petitioners Exhibit 1002
`
`Page2
`
`Petitioners Exhibit 1002
`Page2
`
`
`
`
`
`-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 Application Serial
`No. 09/798,511, filed March 2, 2001, and entitled Stator Assembly Made From
`A Plurality Of Toroidal Core Arc Segments And Motor Using Same, whichis
`hereby incorporated by reference.
`
`FIELD OF THE INVENTION
`
`The presentinvention relates generally to a stator assembly usedin a
`dynamoelectric machine such as a motoror a generator.
`It relates particularly
`to a spindle motor such as usedin a hard disc drive, and to the construction
`and arrangementof a stator assembly madefrom 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 by laminating
`together stamped piecesof steel. These stamped pieces of steel are
`generally circular in nature, but also have “poles” extending either inwardly or
`outwardly, depending on whetherthe rotoris on the inside or surrounds the
`stator. The stamped pieces are laminated together and then coated with
`insulation. Wire is then wound aroundthe 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 whichis usually made from die cast aluminum, a
`stator 4, a shaft 6, bearings 7 and a disc support member8, also referred to
`as a hub. A magnet3 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
`
`10
`
`15
`
`20
`
`25
`
`30
`
`Petitioners Exhibit 1002
`Page3
`
`Petitioners Exhibit 1002
`Page3
`
`
`
`
`
`formed in the base 2 and the disc support member8 to accommodatethe
`bearings 7. One endof the shaft 6 is inserted into the bearing 7 positioned in
`the base 2 and the other endofthe shaft 6 is placed in the bearing 7 located
`in the hub 8. A separate electrical connector 9 mayalso beinserted into the
`
`base 2.
`
`Eachof these parts must befixed at predefined tolerances with respect
`to one another. Accuracyin these tolerances can significantly enhance motor
`
`performance.
`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 engagesin
`
`reading or writing activities based uponinstructions 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
`uponthe 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 uponthe dimensional consistency
`or tolerances between the various componentsof the motor. Greater
`
`dimensional consistency between componentsleads to a smaller gap
`between the stator 4 and the magnet3, producing more force, which provides
`more torque and enables faster acceleration and higherrotational speeds.
`The conventional method of forming stators has a numberof
`
`drawbacks. First, most steel is manufacturedin 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 piecesofsteel, the grain
`orientation differs at different points around thecircle. Compared from the
`radius line 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
`
`10
`
`15
`
`20
`
`25
`
`30
`
`Petitioners Exhibit 1002
`
`Page4
`
`Petitioners Exhibit 1002
`Page4
`
`
`
`
`
`-3-
`
`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 drawbackwith using circular steel piecesis that, especially for
`
`inward facing poles, it has been difficult to wind the wire windings tightly
`
`because of the cramped spaceto 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 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
`
`10
`
`increases the power and thus theefficiency 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 of all the tolerances ofall the parts, as well as the overall tolerance
`
`15
`
`that relates to the alignment of the parts relative to one another. One source
`
`of stack up tolerances is from the circular stator body. Generally, the
`
`thicknessof rolled steel is not uniform across the width of the roll. Sometimes
`
`the edgesare thicker or thinner than the center.
`
`In a stator made from
`
`circular stamped pieces, the thicknessesof individual laminations are thus
`
`20
`
`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.
`
`Another important factor in motor design is the lowering of the
`
`operating temperature of the motor.
`
`Increased motor temperature affects the
`
`25
`
`electrical efficiency of the motor and bearing life. 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
`
`30
`
`Petitioners Exhibit 1002
`
`Page5
`
`Petitioners Exhibit 1002
`Page5
`
`
`
`
`
`-4-
`
`the read/write heads to follow data tracks on the magnetic media. One
`
`drawbackwith existing motor designsis their limited effective dissipation of
`the heat, and difficulty in incorporating heat sinks to aid in heat dissipation.
`addition, in current motors the operating temperatures generally increase as
`
`In
`
`the size of the motor is decreased.
`
`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
`heads during the operation of the drive. Of primary concern are glues used to
`
`attach components together, varnish usedto 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
`
`10
`
`15
`
`reduce the 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 shown in U.S. Patent No. 5,694,268
`
`(Dunfield et al.) (incorporated herein by reference). Referring to FIG. 5 ofthis
`
`20
`
`patent, a stator of the spindle motor is encapsulated with an overmold 42.
`
`The overmolded stator 40 contains openings through which mounting pins 44
`
`maybeinserted 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 drawbackwith the stators
`
`29
`
`described in these patentsis this difficulty in winding wire on the poles.
`
`Another drawbackis the height of the lamination stacks. Further, the
`
`overmolds shownin these patents are noteffective in dissipating heat or
`dampening somevibrations generated by energizing the stator windings.
`U.S. Patent No. 5,806,169 (Trago) (incorporated herein by reference)
`
`30
`
`discloses a method of fabricating an injection molded motor assembly.
`
`However, neither the Trago design northe otherprior art designs address the
`
`problems of winding wire, variation in the thickness of steel used to make the
`
`Petitioners Exhibit 1002
`
`Page6
`
`Petitioners Exhibit 1002
`Page6
`
`
`
`
`
`-5-
`
`stator cores and the non-uniform grain structure in the steel comparedto the
`magnetic flux in the stator during operation of the motor.
`Someof these problems have been addressed by motor manufacturing
`methodsin which individual stator arc segments 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. Somehowthe 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 togetherfor the poles that are of the
`same phase. These numerouswirestendto get in the way during the
`assembly process, slowing down the manufacturing process.
`U.S. Patent No. 6,049,153 to Nishiyama describes the use of crimping
`or welding to attach segments together. This process deformsthe steel and .
`reduces the level of magnetic flux produced by the laminations. The process
`also requires numerouswire interconnections when the poles are wound as
`discrete components, andit does not offer improvements in wire routing.
`U.S. Patent No. 5,729,072 to Hirano describes the use of welding or an
`adhesive to hold the segments together. A disadvantage of this approachis
`that the stator poles must be handled as separate elements during stator
`construction. This requires complicated assembly equipment and a slow
`
`manufacturing process.
`U.S. Patent 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 doesit aid in connecting the various wires.
`o
`U.S. Patent No. 6,167,610 to Nakahara describes a method of making
`a rotary motor wherea length ofsteel strip has thin portions between blocks
`of pole teeth. Wire is wound onthe pole teeth while the steelstrip is straight.
`Later the thin sections are bentto 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
`
`10
`
`15
`
`20
`
`29
`
`30
`
`Petitioners Exhibit 1002
`
`Page?
`
`Petitioners Exhibit 1002
`Page7
`
`
`
`
`
`-6-
`
`and result in large amount of scrap. Thus, a need exists for a method of
`making motors overcoming the aforementioned problems.
`
`BRIEF SUMMARYOF THE INVENTION
`
`A method of making stator assemblies has been invented which
`overcomes manyof the foregoing problems.
`In addition, unique stator
`assemblies and other components of a 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 material also comprises a bridge between adjacent
`segmentsto link adjacent segments into a continuousstrip; 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 arc segments during a
`winding operation comprising: a) a plurality of stator arc segments; and b) a
`phase change material constituting said flexible carrier adhered to the stator
`arc segments whichlinks 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 segmentslinked
`together by a phase change material and each constituting a pole and having
`a first side surface and a secondside 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 segmentis in contact with an opposing side surface of
`another segment; and d) substantially encapsulating said toroidal core with a
`monolithic 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 segmentslinked
`together by a phase change material and each providing a pole and having a
`
`10
`
`15
`
`20
`
`25
`
`Petitioners Exhibit 1002
`
`Pages
`
`Petitioners Exhibit 1002
`Page8
`
`
`
`
`
`-7-
`
`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 eachsaid side surface of one segmentis in contact with an opposing
`
`side surface of another 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 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 be used to wind all poles in the sameseries or phase, makingit
`
`unnecessary to later connect wires from individual windings to one another. The
`invention provides the foregoing and other features, and the advantagesofthe
`invention will becomefurther apparent from the following detailed description of
`
`the presently preferred embodiments, read in conjunction with the
`accompanying drawings. The detailed description and drawings are merely
`
`illustrative of the invention and do notlimit the scope of the invention, whichis
`
`defined by the appended claims and equivalents thereof.
`
`10
`
`15
`
`20
`
`BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS
`
`FIG. 1 is an exploded, partial cross-sectional and perspective 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 change material to makealimited
`
`25
`
`30
`
`series of stator arc segments of the presentinvention.
`FIG. 3 is a perspective, partial cross-sectional view of an encapsulated
`
`stator arc segmentof FIG. 2.
`FIG. 4 is a perspective view of the encapsulated stator arc segmentof
`
`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.
`
`Petitioners Exhibit 1002
`
`Page9
`
`Petitioners Exhibit 1002
`Page9
`
`
`
`HOWAB OE
`ai oh
`ry
`fa Ege Bad
`
`-8-
`
`FIG. 6 is a perspective view of the series of stator arc 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 seqments of FIG. 6.
`
`FIG. 8a is a cross-sectional view of a toroidal core made from the
`
`linked series of stator arc segmentsafter the wire winding shownin 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 change material, resulting in
`
`10
`
`the stator assembly of FIG. 7.
`
`FIG. 9 is an exploded, partial cross-sectional and perspective view of a
`
`motor using the encapsulated webbedstator of FIG. 7.
`
`FIG. 10 is a perspective view of a stator assembly of a second
`
`embodimentof the present invention using a steel band to unitize the webbed
`
`15
`
`stator arc segments.
`
`DETAILED DESCRIPTION OF THE DRAWINGS AND PREFERRED
`EMBODIMENTS OF THE INVENTION
`
`A preferred embodiment of a motor of the present invention and
`
`portions of the motorat different stages of manufacture are shownin FIGS. 2-
`
`20
`
`7 and 9. The spindle motor 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 byinjection molding a
`
`plurality of stator arc segments 20 (FIG. 2) aligned to form a toroidal core 17
`
`(FIG. 7). Although the embodiment described here usesindividual arc
`
`25
`
`segments, one of ordinary skill in the art will understand that groups of two,
`
`three or any greater numberof arc segments may be used. The preferred
`
`motor of the present invention may be smailer, has a grain structure thatis
`
`more uniformly aligned, and allows for greater packing density of wire and
`
`reduces waste of steel in the manufacturing process, as compared with
`
`30
`
`conventional motors, thereby increasing power and reducing stack up
`
`Petitioners Exhibit 1002
`
`Page10
`
`Petitioners Exhibit 1002
`Page10
`
`
`
` castles
`
`-9-
`
`tolerances and manufacturing costs and producing other advantages
`
`discussed below.
`
`Referring to FIG. 2, a stator arc segment 20is first constructed, using
`
`steel laminations 11. The stator arc segment20 is made ofsteel pieces that
`
`are stampedoutof rolled steel. The stamped steel pieces are arc segments,
`
`but also have a pole 21 extending inwardly or outwardly depending on
`
`whether the rotor is inside or surrounds the stator.
`
`In the embodiment shown
`
`in FIG. 2, the pole 21 is shown extending inwardly. The stamped pieces are
`
`then coated with encapsulating material 22 which provides electrical insulation
`
`10
`
`and laminates the pieces together to form a stator arc segment20, 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
`
`15
`
`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
`
`20
`
`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 mostpreferred temperature activated phase change materials are
`
`thermoplastics. The preferred thermoplastic will become molten at a
`
`25
`
`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.
`
`30
`
`As shownin FIG. 2 the segments 20 can be placed in a multi-cavity
`
`mold 28 to increase productivity.
`
`In the preferred embodimentthe individual
`
`laminations 11 making up the segments are not interconnected but loosely
`
`Petitioners Exhibit 1002
`
`Page11
`
`Petitioners Exhibit 1002
`Page11
`
`
`
`
`
`-10-
`
`stacked together before insertion into the mold 28. After the thermoplastic
`
`solidifies, the overmolded segments are ejected from their cavities. New
`
`laminations are inserted into the cavities and the process repeats.
`In the
`preferred embodiment, 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 anotheras theywill be in
`the finished stator assembly.
`
`The stator arc segments 20 are preferably molded into a continuous
`
`In the
`strip where the webbing acts as a carrier to link the segments together.
`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 phasepoles, thus
`
`eliminating the need for interconnections commonly used on segmented
`stator motors. This greatly enhancesthe efficiency for winding wire 15 around
`the poles 21 and significantly reduces the cost.
`
`The webbing can bedeflected to allow the gap betweenadjoining
`poles to be increased as is shownin 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 needies 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. Poles 21 in other phasesare also
`
`10
`
`15
`
`20
`
`25
`
`30
`
`similarly wound. Having only arc segments, rather than a full toroidal core,
`
`and spreading the spacing between the adjoining segments for needle 35 to
`
`Petitioners Exhibit 1002
`
`Page12
`
`Petitioners Exhibit 1002
`Page12
`
`
`
`
`
`-11-
`
`wind wire 15 around poles 21, allows a wire packing density of more than 80
`
`percent to be achieved.
`
`A length of connected stator segments 20 corresponding to the number
`
`of poles 21 required to produce the motor are cut from the continuous strip.
`
`The strip is then rolled into 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, a side surface 16 of each stator arc segment 20
`is aligned and brought into contact with a corresponding side surface of
`
`another stator arc segment 20.
`
`In certain embodiments where a reduction in
`
`10
`
`eddy currents is desirable, it may be preferable to separate faces 16. This
`
`15
`
`20
`
`25
`
`could be done byusing a thin film of encapsulation material 22 over the side
`
`surfaces 16, or the edges 19 of the insulator end surface (FIG. 4) could be
`
`used to create the gap. 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.
`As shownin FIG. 7, the toroidal core 17 is then encapsulated in a body
`42. Together the toroidal core 17 and the body 42 make up an injection
`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. Wires 44 extend out of the
`
`body 42 for connection to the power source used to supply the motor.
`Substantial encapsulation means that 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
`means that the body 42 and toroidal core 17 arerigidly fixed together, and
`behave as a single component with respect to harmonic oscillation vibration.
`
`The preferred method of developing the monolithic body 42 comprises
`designing a phase change material to have a coefficient of linear thermal
`
`expansion suchthat the phase change material contracts and expands at
`
`30
`
`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
`
`Petitioners Exhibit 1002
`
`Page13
`
`Petitioners Exhibit 1002
`Page13
`
`
`
`
`
`-12-
`
`change material should have a CLTEthat is intermediate the maximum and
`
`minimum CLTE ofthe toroidal core and other motor components where the
`
`body is in contact with those other components and they are made of a
`
`different material than the core. Also, the CLTE’s of the body andtoroidal
`
`core should match throughout the temperature range of the motor during its
`
`operation. An advantage of this method is that a more accurate tolerance
`
`may be achieved between the body and the componentsof the toroidal core
`
`because the CLTEof the body matches the CLTEof the toroidal core
`
`components more closely. Most often the toroidal core componentswill be
`
`10
`
`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 temperaturesthat 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 on the direction
`of measurement, the relevant CLTE for purposes of defining the present
`invention is the CLTE in the direction in which the CLTE is lowest. However,
`
`if a material has a rate of expansion in one direction that is more thanfive
`
`times greater than the expansion rate in one of the other directions, then the
`
`CLTEfor purposesof defining the present invention is average of the CLTEs
`in each of the three X, Y and Z directions.
`
`The CLTE of commonsolid 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
`
`15
`
`20
`
`25
`
`30
`
`Petitioners Exhibit 1002
`
`Page14
`
`Petitioners Exhibit 1002
`Page14
`
`
`
`
`
`-13-
`
`Of course,if the motor is designed with two or moredifferent solids,
`such as steel and aluminum components, the CLTEof the phase change
`material would preferably be one that was intermediate the maximum CLTE
`and the minimum CLTEofthe different solids, such as 0.65 in/in/°F at room
`temperature and 1.1 x10° in/in/°F at 250°F.
`
`One preferred thermoplastic material, Konduit OTF-212-11, which
`includes aluminum oxide asa filler at level of about 55%, was madeinto a
`thermoplastic body and testedfor its 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 CLTEin 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 purposesof 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 CLTEin 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°C of 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 PPS 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 0.4 watts/meter°K using
`ASTMtest procedure 0149 and tested at room temperature (23°C).
`In the present embodiment, the phase change material used to make
`the body 42is preferably a thermally conductive but non-electrically
`conductive plastic.
`In addition, the plastic preferably includes ceramicfiller
`particles such as aluminum oxide or boron nitride that enhance the thermal
`conductivity, while reducing the coefficient oflinear thermal expansion of the
`
`10
`
`15
`
`20
`
`25
`
`30
`
`Petitioners Exhibit 1002
`
`Page15
`
`Petitioners Exhibit 1002
`Page15
`
`
`
`“OW ya
`ath.tad!idl aaa
`
`-14-
`
`plastic. Thefiller will preferably comprise about 30% or more of the phase
`change material, more preferably about 45% or more, and most preferably
`about 55% or more. A preferred form ofplastic is polyohenyl sulfide (PPS)
`sold under the tradename “Konduit” by LNP. Grade OTF-212-11 PPS is
`particularly preferred, using a roughly 55 weight percentage of aluminum
`oxide asa filler. Examples of other suitable thermoplastic resins include, but
`are not limited to, thermoplastic resins such 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 polyamideblends,
`and polycarbonate and polybutylene terephthalate, may also be usedinthis
`invention.
`
`10
`
`15
`
`20
`
`Of course, two different phase change materials can be usedfor the
`encapsulating material 22 and the body 42. The encapsulating material 22
`will normally beareally stiff, high temperature thermoplastic, whereas, the
`body 42 will normally be made of a more compliant thermoplastic.
`As shownin FIG. 8a, to encapsulate the toroidal core 17 and form body
`42, the series of stator ar