111111
`
`1111111111111111111111111111111111111111111111111111111111111
`US007928348B2
`
`c12) United States Patent
`Neal
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 7,928,348 B2
`Apr. 19, 2011
`
`(54) ELECTROMAGNETIC DEVICE WITH
`INTEGRATED FLUID FLOW PATH
`
`(75)
`
`Inventor: Griffith D. Neal, Alameda, CA (US)
`
`(73) Assignee: Encap Technologies Inc., 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 1171 days.
`
`(21) Appl. No.: 11/489,911
`
`(22) Filed:
`
`Jul. 19, 2006
`
`(65)
`
`Prior Publication Data
`
`US 2008/0029506 AI
`
`Feb. 7,2008
`
`(51)
`
`Int. Cl.
`HOSB 6110
`(2006.01)
`H02K 9120
`(2006.01)
`(52) U.S. Cl. ............................. 219/628; 310/54; 310/43
`(58) Field of Classification Search .................. 219/628;
`310/43, 54, 55, 67 R, 89, 90, 156.23; 165/104.14,
`1651212,214,272.4,285, 311; 62/101
`See application file for complete search history.
`
`(56)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`4,678,881 A * 7/1987 Griffith ......................... 219/631
`5,534,097 A * 7/1996 Fasano eta!.
`156/214
`
`8/2004 Nakata eta!. ............... 440/89 R
`3/2006 Johnson et al ........... 310/156.23
`4/2007 Huang eta!. .................. 264/489
`
`6,783,413 B2 *
`2006/0055264 A1 *
`2007/0075463 A1 *
`FOREIGN PATENT DOCUMENTS
`63118559 A * 5/1988
`JP
`* cited by examiner
`
`Primary Examiner- Quang T Van
`(74) Attorney, Agent, or Firm- Brinks Hofer Gilson &
`Liane; Steven P. Shurtz
`
`(57)
`
`ABSTRACT
`
`Electromagnetic components are provided with a heat
`exchange mechanism. For example, a fluid-cooled electro(cid:173)
`magnetic field-functioning device, such as a motor, generator,
`transformer, solenoid or relay, includes one or more electrical
`conductors. A monolithic body of phase change material
`substantially encapsulates the conductors or an inductor. At
`least one liquid-tight coolant channel is also substantially
`encapsulated within the body of phase change material. The
`coolant channel may be part of a heat pipe or cold plate. The
`coolant channel may be made by molding a conduit into the
`body, using a "lost wax" molding process, or injecting gas
`into the molten phase change material while it is in the mold.
`The coolant channel may also be formed at the juncture
`between the body and a cover over the body.
`
`27 Claims, 14 Drawing Sheets
`
`Page 1 of 28
`
`PETITIONERS' EXHIBIT 1001
`
`

`

`U.S. Patent
`U.S. Patent
`
`Apr. 19, 2011
`Apr. 19, 2011
`
`Sheet 1 of 14
`Sheet 1 of 14
`
`US 7,928,348 B2
`US 7,928,348 B2
`
`-
`
`
`
`- I -
`• a::
`<.9~
`-Q
`LL~
`
`\
`
`Page 2 0f 28
`
`Page 2 of 28
`
`

`

`U.S. Patent
`U.S. Patent
`
`Apr. 19, 2011
`Apr. 19, 2011
`
`Sheet 2 of 14
`Sheet 2 of 14
`
`US 7,928,348 B2
`US 7,928,348 B2
`
`
`
`Page 3 0f 28
`
`Page 3 of 28
`
`

`

`U.S. Patent
`US. Patent
`
`Apr. 19, 2011
`Apr. 19, 2011
`
`Sheet 3 of 14
`Sheet 3 of 14
`
`US 7,928,348 B2
`US 7,928,348 B2
`
`FIG.4
`F164 54
`
`42
`
`50 52
`
`46
`
`
`
`filo
`
`
`
`62
`40
`5: 1H
`(3%
`
`
`62
`:51
`g;
`L“- ‘
`
`I \
`
`
`
`16 -
`
`18
`
`30
`..........
`
`
`
`
`
`
`
`58
`
`17
`
`48
`
`Page 4 0f 28
`
`Page 4 of 28
`
`

`

`U.S. Patent
`US. Patent
`
`A r. 19 2011
`Apr. 19, 2011
`
`Sheet4 of 14
`Sheet 4 of 14
`
`US 7,928,348 B2
`
` EIii/nI,krill-4w.gflmfi‘na
`
`
`Iniiw!..
`.1”A_§\\1m,
`113w?..\Wgran-mafia»
`“w.1ru’uflmf’
`Ll‘W’MwfiyON
`
`
`Pm.
`
`mam.
`
`•
`I
`I.() I
`.
`
`I
`
`<..9 -LL
`
`l
`
`
`
`b
`C\1
`
`I
`
`Page 5 of 28
`
`
`
`

`

`U.S. Patent
`US. Patent
`
`Apr. 19, 2011
`Apr. 19, 2011
`
`Sheet 5 of 14
`Sheet 5 of 14
`
`US 7,928,348 B2
`US 7,928,348 B2
`
` l
`
`
`1/O
`[neg
`W\_
`‘
`
`
`2l2
`
`’)
`
`Page 6 0f 28
`
`Page 6 of 28
`
`

`

`U.S. Patent
`U.S. Patent
`
`Apr. 19, 2011
`Apr. 19, 2011
`
`Sheet 6 of 14
`Sheet 6 of 14
`
`US 7,928,348 B2
`US 7,928,348 B2
`
`v
`
`gm
`
`“Emma/9%:fififififififimwkfifiwfifi:§155“
`
`
`
`
` Sm
`8m08m5
`
`Q)
`.
`(_') -
`LL
`
`Page 7 0f 28
`
`7 §
`
`I“"""‘A
`§§
`74’‘74747437435
`.v-V\hfitsh‘i
`"ggg‘
`4’Eg
`
`:22“y9'
`
`NNO,.
`
`who.
`
`Hugo
`
`•
`
`(_') -
`
`“lam?
`gggggflVa.i‘lligfigj..riiggiil
`1‘~\Ni.)N!L“‘5.ESE-ah.“‘~\‘L
`
`
`..L..l’ggg‘gd..igggflg
`"i‘r’i‘g‘l..gfiifliii"!
`.Eggggg
`.i‘l’g‘l‘u"
`
`.lJV’IIIIIIL‘il‘l!
`
`"r‘iiii‘..fillil"“
`\§§\\.fi%§§§\§Aigggglr‘“IgigiglaIVgggggflu.Egggg‘a\":“““‘i_.i‘:"“"flflu.7“:"‘:’
`
`ligi"‘£‘n7‘5:5“]!I'l"!in.“rigi"ilr§v
`
`
`“{‘h““‘~‘.‘1‘..I.‘5-1.3...
`
`Page 7 of 28
`
`
`
`
`
`
`
`

`

`U.S. Patent
`US. Patent
`
`Apr. 19, 2011
`Apr. 19, 2011
`
`Sheet 7 of 14
`Sheet 7 of 14
`
`US 7,928,348 B2
`US 7,928,348 B2
`
`c S
`
`".
`
`0
`FIGIO
`(.9 -
`
`•
`
`«> ---
`
`["6
`
`Page 8 0f 28
`
`Page 8 of 28
`
`

`

`U.S. Patent
`
`Apr. 19, 2011
`
`Sheet 8 of 14
`
`US 7,928,348 B2
`
`FIG. 11
`
`~
`I
`
`1102
`
`i I
`
`'
`
`•
`
`w I .
`
`' !
`
`·.~.-;·-.
`.
`
`. .
`. .
`
`'
`
`.
`
`.
`
`.
`- ·.
`
`.
`-
`
`.
`
`1124
`
`!
`~-oL<>-
`j ! 1130 ~ .. :
`I
`. .·· . ..
`1 L.//111!
`
`1112
`
`~41L!J~~
`
`I I
`
`Page 9 of 28
`
`

`

`00 = N
`00 w
`N
`\c
`-....l
`rJl
`d
`
`~
`
`....
`0 .....
`\0
`('D a
`rFJ =(cid:173)
`
`.j;o.
`
`285
`
`....
`0 ....
`'e :-: ....
`>
`
`N
`\0
`
`~
`
`~ = ~
`
`~
`~
`~
`•
`00
`~
`
`FIG. 13
`
`~ ... ~.Amilnn-hmnffllmii'
`Fl G. 12 284273 /27{)
`
`Page 10 of 28
`
`

`

`00 = N
`00 w
`N
`\c
`-....l
`rJl
`d
`
`US 7,928,348 132
`
`~
`
`....
`0 .....
`0
`..... ....
`rFJ =(cid:173) ('D
`
`Sheet 10 of 14
`
`.j;o.
`
`('D
`
`> 'e :-: ....
`
`Apr. 19, 2011
`
`....
`0 ....
`
`N
`~'-CI
`
`~ = ~
`
`~
`~
`~
`•
`00
`~
`
`U.S. Patent
`
`«mm“My.
`.‘35..
`
`.u
`
`\
`
`a:
`
`~
`
`2.»;
`
`FlG.14~
`
`Page 11 0f 28
`
`Page 11 of 28
`
`

`

`U.S. Patent
`
`Apr. 19, 2011
`
`Sheet 11 of 14
`
`US 7,928,348 B2
`
`(9
`
`LL
`
`Page 12 of 28
`
`

`

`U.S. Patent
`
`Apr. 19, 2011
`
`Sheet 12 of 14
`
`US 7,928,348 B2
`
`FIG. 17
`
`362
`
`~
`
`~// _/ L
`
`/
`
`350
`
`i
`
`~
`
`."-
`
`,•
`
`.. ~t\
`. '
`~["-
`
`-
`
`-
`
`..
`
`..
`
`. -
`
`(
`I
`
`. .
`
`['..
`
`..
`
`•·
`
`..
`
`.....
`
`0""
`1." ..
`::
`
`..
`
`·.
`-
`
`:,,
`
`-
`:··",
`
`-
`
`..
`
`,_
`
`'
`
`..
`~ ..
`..
`. , .
`·.
`
`. .
`
`.rs- /
`/ / L / __ f',
`~
`,-~,l.-;358
`~
`~
`352 ~rv357
`-;. ·~"'--~'"
`. ..
`35G
`I~
`_., K .
`f-.'
`..
`. . f'_
`. ..
`-17\
`
`''
`~
`~
`~ 354
`[\:
`~""'-X"'-'
`'
`
`-..
`
`...
`
`....
`
`L
`
`/
`
`.- .
`.. ···
`,.
`
`. .
`
`..
`'-
`
`.
`
`.
`
`-~
`
`-~
`
`:
`
`·..
`
`--
`•
`
`1-\
`.,
`~
`~\~- ' '
`~-'" ~ .
`..
`. . . l"~'- 364
`,,
`. .
`'
`364/' '
`~r~
`~· -
`~ '~~'''<~
`\..
`360
`
`Page 13 of 28
`
`

`

`Apr. 19, 2011
`
`U.S. Patent
`FIG.18
`
`42
`
`Sheet 13 of 14
`
`US 7,928,348 B2
`
`19
`
`--t
`20/
`
`400
`
`FIG. 19
`
`406
`
`Page 14 of 28
`
`

`

`U.S. Patent
`
`Apr. 19,2011
`
`Sheet 14 of 14
`
`US 7,928,348 B2
`
`F \G. 20 47~0-------- 468
`
`_r450
`452 f
`
`456
`
`F\G.21
`
`47Z
`
`Page 15 of 28
`
`

`

`US 7,928,348 B2
`
`1
`ELECTROMAGNETIC DEVICE WITH
`INTEGRATED FLUID FLOW PATH
`
`FIELD OF THE INVENTION
`
`The present invention relates generally to electromagnetic
`devices that include heat exchange mechanisms. It relates
`particularly to motors, generators, transformers, relays and
`solenoids that are cooled by a fluid coolant. The devices can
`be used in various electronic products, such as a motor for
`hard disc drive or other consumer electronic device, a pump
`motor, a motor/generator used in a hybrid electric vehicle, a
`motor used in an air blower and a solenoid used in a fuel
`injector or liquid flow valve.
`
`BACKGROUND OF THE INVENTION
`
`The present invention utilizes aspects of Applicant's earlier
`inventions, some of which are repeated herein. U.S. Pat. Nos.
`6,362,554; 6,753,682 and 6,911,166, which are hereby incor(cid:173)
`porated by reference, further disclose some of these concepts.
`An example of a conventional 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 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 end of the 30
`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 predefined tolerances 35
`with respect to one another. Accuracy in these tolerances can
`significantly enhance motor performance.
`An important factor in motor design is the lowering of the
`operating temperature of the motor. Increased motor tem(cid:173)
`perature affects the electrical efficiency of the motor and 40
`bearing life. As temperature increases, resistive loses in wire
`increase, thereby reducing total motor power. Furthermore,
`the Arrhenius equation predicts that the failure rate of an
`electrical device is exponentially related to its operating tem(cid:173)
`perature. The frictional heat generated by bearings increases 45
`with speed. Also, as bearings get hot they expand, and the
`bearing cages get stressed and may deflect, causing non(cid:173)
`uniform rotation and the resultant further heat increase. One
`drawback with existing motor designs is their limited effec(cid:173)
`tive dissipation 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.
`Electromagnetic devices used in electrical products may
`need to be cooled to remove heat generated by operation of
`the device. It is well known that a fluid in the environment of
`the device can be used to aid cooling. As an example, a
`method of cooling a motor is to include a fan on the motor
`shaft. The fan then blows air past the motor. Air, however, has
`a fairly low heat capacity, and thus cannot carry away as much 60
`heat as is sometime generated by the motor. Also, in some
`applications there is no place to mount a fan. Other fluids, and
`liquids in particular, typically have a high enough heat capac-
`ity that they can be used to carry away heat. For example, a
`water pump driven by a motor uses the water to cool the
`pump. The problem with liquids, however, is getting them in
`contact with hot motor surfaces without damaging the motor,
`
`2
`and then collecting them to carry them away. Thus, a need
`exists for an improved motor that includes an effective and
`practical way of using a liquid to carry heat away from the
`motor. Also, a need exits for improved methods of cooling
`other electromagnetic components.
`Also, there are times when the heat generated by operation
`of the electrical device, such as a motor, could be put to a
`beneficial use if there were a way to confine a fluid used in a
`heat transfer relationship with the device so that it could be
`10 directed to a point of desired use. Thus, if liquids or gasses
`could be channeled in such a way that they picked up heat
`from an electromagnetic device without damaging the device,
`and then carried that heat to a place where the heat was
`15 desired, that would be a great benefit.
`One difficulty encountered in the design of electrical com(cid:173)
`ponents is that various components need to withstand expo(cid:173)
`sure to solvents and particulates. The environmental agents
`can corrode the conductors or inductors in the component. In
`20 pumps used for movement of corrosive agents, this can be a
`particular problem. In hybrid electric vehicles where the
`motor or generator resides inside of the transmission housing,
`stray metallic debris generated from the transmission gears
`may be thrown into the windings, damaging them to the point
`25 that the device no longer works.
`
`BRIEF SUMMARY OF THE INVENTION
`
`Electromagnetic devices have been invented which over-
`come many of the foregoing problems. In one class of
`devices, a heat transfer fluid flows through the device. In
`another class of devices, a heat transfer fluid is contained
`within the device. Encapsulating portions of the device at the
`same time a heat exchange mechanism is provided may pro(cid:173)
`vide the additional benefit of protecting the parts from corro(cid:173)
`sive or otherwise damaging environments.
`In a first aspect, the invention is an electromagnetic field(cid:173)
`functioning device for heating a fluid comprising at least one
`electrical conductor that generates heat when in use; a mono(cid:173)
`lithic body of injection molded thermoplastic material sub(cid:173)
`stantially encapsulating the at least one conductor; and a fluid
`pathway in the monolithic body, with at least one fluid inlet
`and at least one fluid outlet to the pathway to allow for passage
`of fluid through the pathway, the outlet directing the fluid to a
`place of usage wherein heat picked up by the fluid as it
`transfers through the device is put to functional use.
`In a second aspect, the invention is an electromagnetic
`field-functioning device for heating a fluid comprising at least
`50 one electrical conductor that generates heat when in use; a
`monolithic body of injection molded thermoplastic material
`substantially encapsulating the at least one conductor; and a
`fluid pathway in the monolithic body, with at least one fluid
`inlet and at least one fluid outlet to the pathway to allow for
`55 passage of fluid through the pathway, the outlet directing the
`fluid to a place of usage wherein heat picked up by the fluid as
`it transfers through the device is put to functional use, and
`further wherein the monolithic body completely surrounds
`the device except for the inlet and the outlet.
`In a third aspect, the invention is an electromagnetic field-
`functioning device for heating a fluid comprising at least one
`electrical conductor and at least one inductor that generates
`heat when in use; a monolithic body of injection molded
`thermoplastic material substantially encapsulating the at least
`65 one inductor; and a fluid pathway in the monolithic body, with
`at least one fluid inlet and at least one fluid outlet to the
`pathway to allow for passage of fluid through the pathway, the
`
`Page 16 of 28
`
`

`

`US 7,928,348 B2
`
`4
`formed by injecting gas into the molten thermoplastic after it
`has been injected into a mold but before it solidifies to form
`the body encapsulating the motor component, or component
`of other electromagnetic field-functioning devices. The fore(cid:173)
`going and other features, and the advantages of 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 merely illustrative of the inven-
`10 tion 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
`
`3
`outlet directing the fluid to a place of usage wherein heat
`picked up by the fluid as it transfers through the device is put
`to functional use.
`In a fourth aspect, the invention is a fluid conveying mecha(cid:173)
`nism comprising an electromagnetic field-functioning device
`having at least one electrical conductor; a monolithic body of
`injection molded thermoplastic material substantially encap(cid:173)
`sulating the at least one conductor; and a fluid pathway in the
`monolithic body, with at least one of a fluid inlet into the
`pathway and a fluid outlet from the pathway being formed in
`the body of injection molded thermoplastic, and the pathway
`through the body being confined within the body.
`In another aspect, the invention is a fluid-cooled electro(cid:173)
`magnetic field-functioning device comprising one or more
`electrical conductors; a heat transfer fluid confinement mem- 15
`ber; and a monolithic body of phase change material substan(cid:173)
`tially encapsulating both the one or more conductors and the
`heat transfer fluid confinement member.
`In yet another aspect the invention is a fluid-cooled elec(cid:173)
`tromagnetic device comprising an assembly comprising i) an 20
`inductor in operable proximity to at least one conductor that
`creates at least one magnetic field when electrical current is
`conducted by the conductor; and ii) a body of a phase change
`material substantially encapsulating the conductor; and at
`least one liquid-tight coolant cham1el substantially encapsu- 25
`lated within the body of phase change material.
`In still another aspect the invention is a fluid-cooled elec(cid:173)
`tromagnetic field-functioning device comprising an inductor
`and at least one conductor that creates at least one magnetic
`field when electrical current is conducted by the conductor; a 30
`heat transfer fluid confinement member containing a heat
`transfer fluid; and a monolithic body of phase change material
`substantially encapsulating at least one of the inductor and the
`at least one conductor, the monolithic body being in thermal
`contact with the heat transfer fluid.
`A further aspect of the invention is a method of making a
`fluid-cooled electromagnetic field-functioning device com(cid:173)
`prising the steps of providing a core assembly comprising an
`inductor and at least one conductor that creates at least one
`magnetic field when electrical current is conducted by the 40
`conductor, substantially encapsulating at least one of the
`inductor and the at least one conductor in a body of phase
`change material; providing a heat transfer fluid confinement
`chamber in the body of phase change material; and, adding a
`heat transfer fluid to the confinement chamber and sealing the 45
`chamber to retain the heat transfer fluid in the chamber.
`In another aspect the invention is a method of cooling an
`electromagnetic field-functioning device wherein the electro(cid:173)
`magnetic field-functioning device comprises one or more
`electrical conductors and a monolithic body of phase change 50
`material substantially encapsulating the one or more conduc(cid:173)
`tors, wherein a heat transfer fluid flows through a confined
`path substantially within the body of phase change material to
`transfer heat away from the conductors.
`In one embodiment, a motor can be cooled by using a heat 55
`pipe embedded in a body of phase change material that also
`substantially encapsulates parts of the motor. In another
`embodiment, a motor can be cooled by passing liquid through
`a coolant channel encased in the body of phase change mate(cid:173)
`rial also substantially encapsulating the motor component.
`The body of phase change material provides a path for the
`heat to be transferred from the stator to the liquid coolant,
`where it can be carried away. The liquid is also confined, so
`that it does not contact other parts of the motor or get ran(cid:173)
`domly discharged from the motor. Besides motors, other elec- 65
`tromagnetic field function devices may be made with coolant
`channels. The flow path or chamber for the coolant may be
`
`FIG. 1 is an exploded, partial cross-sectional and perspec(cid:173)
`tive view of a prior art high speed motor.
`FIG. 2 is a perspective view of a stator used in a first
`embodiment of the present invention.
`FIG. 3 is an exploded, partial cross-sectional and perspec(cid:173)
`tive view of a high speed motor in accordance with a first
`embodiment of the present invention.
`FIG. 4 is a cross-sectional view of the high speed motor of
`FIG. 3.
`FIG. 5 is a schematic drawing of a mold used to make the
`encapsulated stator of the motor of FIG. 3.
`FIG. 6 is a schematic drawing of the mold of FIG. 5 in a
`closed position.
`FIG. 7 is an exploded, partial cross-sectional and perspec(cid:173)
`tive view of a high speed motor in accordance with a second
`embodiment of the present invention.
`FIG. 8 is a cross-sectional view of a high speed motor in
`accordance with a third embodiment of the present invention.
`FIG. 9 is a cross-sectional view of a high speed motor in
`accordance with a fourth embodiment of the present inven-
`35 tion.
`FIG.10 is a perspective view of a stator, shaft and cold plate
`used in a fifth embodiment of the present invention.
`FIG. 11 is an exploded view of a hard disc drive of the
`present invention using the components of FIG. 10.
`FIG. 12 is a perspective, partially cross-sectional view of a
`motor/generator for an electric vehicle using a liquid cooling
`channel.
`FIG. 13 is a cross sectional view of the motor/generator of
`FIG. 12.
`FIG. 14 is an exploded and partial cross sectional view of
`the motor/generator of FIG. 12.
`FIG. 15 is an enlarged cross-sectional view of a portion of
`the motor/generator of FIG. 12.
`FIG. 16 is a cross-sectional view of a motor in accordance
`with a seventh embodiment of the invention.
`FIG. 17 is a cross-sectional view of a transformer in accor(cid:173)
`dance with the invention.
`FIG. 18 is a cross-sectional view of a solenoid used in a fuel
`injector in accordance with the invention.
`FIG. 19 is a cross-sectional view taken along line 19-19 of
`FIG. 18.
`FIG. 20 is a cross-sectional view of a solenoid flow valve in
`accordance with the invention.
`FIG. 21 is a perspective view of a heat transfer fluid con-
`60 finement member used in the valve of FIG. 20.
`
`DETAILED DESCRIPTION OF THE DRAWINGS
`AND PREFERRED EMBODIMENTS OF THE
`INVENTION
`
`The term "electromagnetic field-functioning device" as
`used in the present application includes electromagnetic
`
`Page 17 of 28
`
`

`

`US 7,928,348 B2
`
`5
`devices that include one or more electrical conductors and use
`an electromagnetic field as part of the function of the device.
`In some embodiments, the device includes a moving part, and
`there is a relationship between movement of the moving part
`and flow of current in the conductors involving one or more
`magnetic fields. For example, in some devices, such as a
`motor or solenoid, current in the one or more conductors
`generates one or more magnetic fields, which generate a force
`that causes movement of the moving part. In other devices,
`such as a generator, the moving part generates a moving
`magnetic field, which in turn induces an electrical current in
`the one or more conductors. In some devices, like transform(cid:173)
`ers, current conducted by the one or more conductors creates
`a magnetic field, and the magnetic field induces a current in a
`second conductor coupled to the magnetic field.
`The term "heat transfer fluid" as used in the present appli(cid:173)
`cation includes both liquids and gases, as well as combina(cid:173)
`tions thereof. While liquids typically have a higher heat
`capacity per unit volume, and will therefore be more fre(cid:173)
`quently used in the present invention, gases, such as air, may
`also serve as heat transfer fluids.
`
`First Embodiment
`
`A first embodiment of a motor of the present invention is
`shown in FIGS. 2-4. The motor may be a "high speed" motor,
`meaning that the motor can operate at over 5,000 rpm. The
`motor 10 is designed for rotating a disc or stack of discs in a
`computer hard disc drive. Motor 10 is formed using an encap(cid:173)
`sulation method which reduces the number of parts needed to
`manufacture the motor as compared with conventional
`motors used for disc drives, thereby reducing stack up toler(cid:173)
`ances and manufacturing costs and producing other advan(cid:173)
`tages discussed below.
`Referring to FIG. 2, a stator 20 is first constructed, using
`conventional steel laminations 11 forming a magnetically
`inducible core 17 having a plurality of poles 21 thereon, and
`wire windings 15 which serve as conductors. The conductors
`induce or otherwise create a plurality of magnetic fields in the
`core when electrical current is conducted through the conduc(cid:173)
`tors. In this embodiment, a magnetic field is induced in each
`of the poles 21.
`The stator 20 is then used to construct the rest of the motor
`10 (FIG. 3). The motor 10 includes a hub 12, which serves as
`a disc support member, the stator 20, a heat transfer fluid
`confinement member 62 and a body 14. Together the stator 20
`and body 14 make up a stator assembly 13. The heat transfer
`fluid confinement member 62 constitutes a heat pipe in the
`embodiment of FIGS. 2-4. The heat pipe has an annular
`shape. Heat pipes function by containing a fluid that carries
`heat from a high-temperature region to a low-temperature
`region, and then migrates back to the high-temperature region
`to repeat the cycle. Many heat pipes include a liquid that
`vaporizes at the temperature encountered in the high-tem(cid:173)
`perature region, and travels as a gas to the low-temperature
`region, where it condenses. The heat pipes preferably include
`an internal capillary structure, such as a wick, saturated with
`the working fluid. As heat is input at the high-temperature
`region (sometimes referred to as the evaporator), fluid is
`vaporized, creating a pressure gradient in the heat pipe. This
`pressure gradient forces the vapor to flow along the pipe to the
`low-temperature region, where it condenses, giving up its
`latent heat of vaporization. The working fluid is then returned
`to the evaporator by the capillary forces developed in the wick
`structure. The heat pipe is sealed to prevent loss of the heat
`transfer fluid. A heat pipe is thus one example of a heat
`transfer fluid confinement member comprising a heat transfer
`
`15
`
`6
`fluid in a sealed system. Heat pipes can be built in a variety of
`shapes. The internal structure of the heat pipe 62 is not shown,
`but may be of any known arrangement, optimized for the
`expected operating temperature of the motor.
`The body 14 is preferably a monolithic body 14. Mono(cid:173)
`lithic is defined as being formed as a single piece. The body 14
`substantially encapsulates the stator 20. Substantial encapsu(cid:173)
`lation means that the body 14 either entirely surrounds the
`stator 20, or surrounds significant areas of the stator that may
`10 be exposed. However, substantial encapsulation means that
`the body 14 and stator 20 are rigidly fixed together, and
`behave as a single component with respect to harmonic oscil(cid:173)
`lation vibration.
`The body 14 is preferably formed of a phase change mate-
`rial, 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
`20 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 encap-
`25 sulate a stator. Preferred temperature activated phase change
`materials will be changed from a liquid to a solid at a tem(cid:173)
`perature in the range of about 200 to 700° F. The most pre(cid:173)
`ferred temperature activated phase change materials are ther(cid:173)
`moplastics. The preferred thermoplastic will become molten
`30 at a temperature at which it 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 14, is an epoxy. Other suitable phase change mate-
`35 rials may be classified as thermosetting materials.
`As shown in FIG. 4, a shaft 16 is connected to the hub or
`disc support member 12 and is surrounded by bearings 18,
`which are adjacent against the body 14. A rotor or magnet 28
`is fixed to the inside of the hub 12 on a flange so as to be in
`40 operable proximity to the stator. The magnet 28 is preferably
`a permanent magnet, as described below. The body 14
`includes a base 22. In addition, mounting features, such as
`apertures 25 (FIG. 3), and terminals comprising a connector
`26 for connecting the conductors to an external power source
`45 are formed as a part of the stator assembly. The terminals 26
`are partially encapsulated in the body 14.
`The heat pipe 62 is positioned in the body 14 so that one end
`is near the stator 20, which will be the high-temperature
`region. The other end has one face that is not covered by the
`50 phase change material. This face is located just below the hub
`12, so that air currents created by the spinning hub can convey
`heat away from the exposed face, which serves as the low(cid:173)
`temperature region. The heat pipe 62 is substantially encap(cid:173)
`sulated in the body 14, as the body 14 surrounds almost all of
`55 the heat pipe 62 except for the minor exposed face, and the
`body 14 and heat pipe 62 are rigidly fixed together, and
`behave as a single component with respect to harmonic oscil(cid:173)
`lation vibration.
`Referring to FIGS. 3-4, the base 22 of the body 14 is
`60 generally connected to the hard drive case (not shown). Con(cid:173)
`necting members (not shown), such as screws, may be used to
`fix the base 22 to the hard drive case, using holes 25 as shown
`in FIG. 3. Alternatively, other types of mounting features such
`as connecting pins or legs may be formed as part of the base
`65 22. The connector 26 is preferably a through-hole pin type of
`connector 26 and is coupled through the hard drive case to the
`control circuit board residing on the outer surface of the base
`
`Page 18 of 28
`
`

`

`US 7,928,348 B2
`
`8
`bearings.Alternatively other types ofbearings, such as hydro(cid:173)
`dynamic or combinations of hydrodynamic and magnetic
`bearings, may be used. The bearings are typically made of
`stainless steel.
`The shaft 16 is concentrically disposed within the interior
`portion 30 of the body 14. The bearings 18 surround portions
`of the shaft 16. As described above, the inner surfaces 52 of
`the bearings are in contact with the shaft 16. The shaft 16
`includes a top portion 54 and a bottom portion 56. The top
`portion 54 of the shaft 16 is fixed to the hub 12. The bottom
`portion 54 of the shaft 16 is free to rotate inside the lower
`bearing. Thus, in this embodiment, the shaft 16 is freely
`rotatable relative to the body 14. The shaft 16 is preferably
`cylindrical shaped. The shaft 16 may be made of stainless
`steel.
`Referring to FIG. 4, the hub 12 is concentrically disposed
`around the body 14. The hub 12 is fixed to the shaft 16 and is
`spaced apart from the body 14. The hub 12 includes a flux
`return ring 58 and the magnet 28. The flux return ring 58 is
`glued to the disc support member. The magnet 28 is glued to
`the hub 12. As shown in FIG. 4, the magnet 28 concentrically
`surrounds the portion of the body 14 that includes the stator
`20. In this embodiment the magnet 28 and stator 20 are
`generally coplanar when the motor 10 is assembled.
`The magnet 28 is preferably a sintered part and is one solid
`piece. The magnet 28 is placed in a magnetizer which puts a
`plurality of discrete North and South poles onto the magnet
`28, dependant on the number of poles 21 on the stator 20. The
`flux return ring 58 is preferably made of a magnetic steel. The
`hub is preferably made of aluminum. Also, the hub may be
`made of a magnetic material to replace the flux return ring.
`As shown in FIGS. 3 and 4, the heat pipe may comprise just
`one circumferential loop. Of course multiple heat pipes or
`35 pipe loops could be provided in the body 14.
`
`7
`(not shown). Alternatively the connector may be a flexible
`circuit with copper pads allowing spring contact interconnec(cid:173)
`tion.
`The stator 20 is positioned in the body 14 generally in a
`direction perpendicular to an interior portion 30. Referring to 5
`FIG. 2, the stator 20 is preferably annular in shape and con(cid:173)
`tains an open central portion 32. The poles 21 extend radially
`outward from this central portion 32. Faces of the poles 21 are
`positioned outward relative to the central portion 32 of the
`stator 20. The body 14 is molded around the stator 20 in a 10
`manner such that the faces of the poles are exposed and are
`surrounded by and aligned concentrically with respect to the
`disc support member 12. Alternatively, the poles may be
`totally encapsulated in body 14 and not be exposed.
`Referring to FIG. 4, the body 14 has an upper portion 40 15
`that extends upwardly from the stator 20. The upper portion
`40 is also preferably annular shaped. The body 14 includes the
`interior portion 30. The interior portion 30 is generally sized
`and shaped to accommodate the bearings 18. The interior
`portion 30 includes an upper support portion 42 and a lower 20
`support portion 44. In the embodiment illustrated in FIG. 4,
`the interior portion 30 is preferably cylindrically shaped.
`The phase change material used to make the body 14 is
`preferably a thermally conductive but non-electrically con(cid:173)
`ductive plastic. In addition, the plastic preferably includes 25
`ceramic filler particles that enhance the thermal conductiv