I IIIII
`111111
`
`
`1111111111111111111111111111111111111111111111111111111111111 1111111111111111111111111111111111111111111111111111111111111
`USOO7067952B2
`US007067952B2
`
`
`c12) United States Patent (12) United States Patent
`Neal
`Neal
`
`(10) Patent No.:
`(10) Patent No.:
`(45) Date of Patent:
`(45) Date of Patent:
`
`US 7,067,952 B2
`US 7,067,952 B2
`Jun. 27,2006
`Jun.27,2006
`
`
`(54) STATOR ASSEMBLY MADE FROM A (54) STATOR ASSEMBLY MADE FROM A
`MOLDED WEB OF CORE SEGMENTS AND
`MOLDED WEB OF CORE SEGMENTS AND
`MOTOR USING SAME
`MOTOR USING SAME
`
`(75)
`(75)
`
`Inventor: Griffith D. Neal, Alameda, CA (US)
`Inventor: Griffith D. Neal, Alameda, CA (US)
`
`
`(73) Assignee: Encap Motor Corporation, Alameda, (73) Assignee: Encap Motor Corporation, Alameda,
`
`CA (US) CA (US)
`
`
`
`( *) Notice: ( *) Notice:
`
`
`Subject to any disclaimer, the term of this Subject to any disclaimer, the term of this
`
`patent is extended or adjusted under 35 patent is extended or adjusted under 35
`U.S.C. 154(b) by 248 days. U.S.c. 154(b) by 248 days.
`
`
`
`
`(21) Appl. No.: 10/383,219 (21) Appl. No.: 10/383,219
`
`
`
`(22) Filed: (22) Filed:
`
`Mar. 5, 2003
`Mar. 5, 2003
`
`(65)
`(65)
`
`Prior Publication Data
`Prior Publication Data
`
`
`
`US 2004/0034988 Al US 2004/0034988 Al
`
`
`
`Feb. 26, 2004 Feb. 26, 2004
`
`Related U.S. Application Data
`Related U.S. Application Data
`
`(63) Continuation-in-part of application No. 09/798,511, (63) Continuation-in-part of application No. 091798,511,
`
`
`filed on Mar. 2, 2001, now Pat. No. 7,036,207. filed on Mar. 2, 2001, now Pat. No. 7,036,207.
`
`
`
`(51) (51)
`
`
`
`(52) (52)
`
`
`
`(58) (58)
`
`Int. Cl.
`Int. Cl.
`H02K 1118
`(2006.01)
`H02K 1118
`(2006.01)
`H02K 15102
`(2006.01)
`H02K 15102
`(2006.01)
`H02K 15110
`(2006.01)
`H02K 15110
`(2006.01)
`U.S. Cl. .......................... 310/259; 310/42; 310/45;
`U.S. Cl. .......................... 3101259; 310/42; 310/45;
`310/218
`310/218
`
`Field of Classification Search ............ 310/42-43, Field of Classification Search ............ 310/42-43,
`310/45,216-218,254,259; 244/432,433,
`310/45, 216-218, 254, 259; 244/432, 433,
`244/433.4; 29/596
`244/433.4; 29/596
`See application file for complete search history.
`See application file for complete search history.
`
`
`
`(56) (56)
`
`References Cited
`References Cited
`
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`U.S. PATENT DOCUMENTS
`
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`
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`
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`
`
`(Continued) (Continued)
`
`
`
`FOREIGN PATENT DOCUMENTS FOREIGN PATENT DOCUMENTS
`
`
`
`BE BE
`
`
`
`870878 870878
`
`
`
`111979 111979
`
`
`
`(Continued) (Continued)
`
`OTHER PUBLICATIONS
`OTHER PUBLICATIONS
`
`
`
`
`LNP Engineering LNP Engineering
`Plastics, Advertisment Plastics, Advertisment
`entitled entitled
`
`"Konduit™ Thermally Conductive Composites," undated (2 ''Konduit™ Thermally Conductive Composites," undated (2
`
`pages). pages).
`
`
`
`(Continued) (Continued)
`
`
`Primary Examiner-Burton Mullins Primary Examiner-Burton Mullins
`
`(74) Attorney, Agent, or Firm-Steven P. Shurtz; Brinks (74) Attorney, Agent, or Firm-Steven P. Shurtz; Brinks
`
`Hofer Gilson & Liane Hofer Gilson & Lione
`
`
`
`(57) (57)
`
`ABSTRACT
`ABSTRACT
`
`
`A plurality of stator arc segments 20 are linked together by A plurality of stator arc segments 20 are linked together by
`
`a phase change material 22 enabling simplified winding and a phase change material 22 enabling simplified winding and
`
`higher slot fill. Once wound this continuous structure can be higher slot fill. Once wound this continuous structure can be
`formed into a toroidal core 17 for a stator assembly 40 used
`formed into a toroidal core 17 for a stator assembly 40 used
`to make a motor 100. In a preferred embodiment, a mono(cid:173)
`to make a motor 100. In a preferred embodiment, a mono(cid:173)
`
`lithic body 42 of phase change material substantially encap(cid:173)lithic body 42 of phase change material substantially encap(cid:173)
`
`sulates the conductors and holds the stator arc segments 20 sulates the conductors and holds the stator arc segments 20
`
`in contact with each other in the toroidal core 17. Hard disc in contact with each other in the toroidal core 17. Hard disc
`
`drives using the motor 100, and methods of constructing the drives using the motor 100, and methods of constructing the
`
`motor 100 are also disclosed. motor 100 are also disclosed.
`
`14 Claims, 5 Drawing Sheets
`14 Claims, 5 Drawing Sheets
`
`
`
`24 24
`
`NIDEC and HONDA - Ex. 1001
`Nidec Corporation and American Honda
`Motor Co., Inc. - Petitioners
`
`1
`
`

`

`
`US 7,067,952 B2 US 7,067,952 B2
`
`Page 2 Page 2
`
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`
`
`FOREIGN PATENT DOCUMENTS FOREIGN PATENT DOCUMENTS
`
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`BE
`DE
`DE
`EP
`EP
`EP
`EP
`FR
`FR
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`OTHER PUBLICATIONS OTHER PUBLICATIONS
`
`
`Product Information from Dupont Engineering Polymers Product Information from Dupont Engineering Polymers
`
`entitled "Electrical/Electronic Thermoplastic Encapsula(cid:173)entitled "Electrical/Electronic Thermoplastic Encapsula(cid:173)
`
`tion," undated, Pub!. Reorder No.: H-58633 (R, 96.7), 20 tion," undated, Publ. Reorder No.: H-58633 (R, 96.7), 20
`
`pages. pages.
`
`LNP Engineering Plastics, Press Release entitled "LNP LNP Engineering Plastics, Press Release entitled "LNP
`
`Introduces First-Ever Line of Thermally Conductive Com(cid:173)Introduces First-Ever Line of Thermally Conductive Com(cid:173)
`
`pounds," Jan. 28, 1999 (2 pages). pounds," Jan. 28, 1999 (2 pages).
`
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`
`entitled "Epoxy Seal-Prevents Down Time and Keeps entitled "Epoxy Seal-Prevents Down Time and Keeps
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`Equipment Running Longer," Jul. 14, 1999, <http://www. Equipment Running Longer," Jul. 14, 1999, <http://www.
`
`bmwworks.cornNIP.htm>, 1 page. bmwworks.comNIP.htm>, 1 page.
`
`

`

`
`US 7,067,952 B2 US 7,067,952 B2
`
`Page 3 Page 3
`
`
`The Epoxy lite Corporation, article from the Internet entitled The Epoxylite Corporation, article from the Internet entitled
`"Vacuum Pressure Impregnation (VPI) Systems", Nov. 19,
`"Vacuum Pressure Impregnation (VPI) Systems", Nov. 19,
`1999,
`<http://www.epoxylite.comlEpoxyliteEquipment.
`1999,
`<http:/ /www.epoxylite.com/EpoxyliteEquipment.
`htm> , 3 pages.
`htm>, 3 pages.
`
`Neeltran Inc., article from the Internet entitled "Vacuum
`Neeltran Inc., article from the Internet entitled "Vacuum
`Pressure Impregnation (VPI)", Nov. 19, 1999, <http://www.
`Pressure Impregnation (VPI)", Nov. 19, 1999, <http://www.
`neeltran. thomasregister.comlolc/neeltranlneeI9 .htm>
`2
`neeltran. thomasregister.com/olc/neeltran/neel9 .htm>
`2
`pages.
`pages.
`
`* cited by examiner * cited by examiner
`
`

`

`u.s. Patent
`U.S. Patent
`
`
`
`Jun.27,2006 Juo.27,2006
`
`
`
`Sheet 1 of 5 Sheet 1 of 5
`
`
`
`US 7,067,952 B2 US 7,067,952 B2
`
`Fl G.l
`FI G.I
`
`PRIOR ART
`
`FIG.2
`FIG.2
`
`

`

`
`
`Jun.27,2006 Juo.27,2006
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`US 7,067,952 B2 US 7,067,952 B2
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`u.s. Patent
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`FIG.3 FIG.3
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`16
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`t t
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`20 20
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`FIG.4 FIG.4
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`FIG.5 FIG.5
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`19 19
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`24 24
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`u.s. Patent
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`Jun. 27, 2006 Jun. 27, 2006
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`US 7,067,952 B2 US 7,067,952 B2
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`FIG.6
`FIG.6
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`21C 21C
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`FIG.742
`FIG.7 42
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`u.s. Patent
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`Jun.27,2006 Juo.27,2006
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`US 7,067,952 B2 US 7,067,952 B2
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`FIG.8a
`FIG. Sa
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`61 61
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`15 15
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`17 17
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`FIG. 8 b 61
`FIG. 8 b 61
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`15 15
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`66-h'~~~
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`u.s. Patent
`U.S. Patent
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`Jun.27,2006 Juo.27,2006
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`US 7,067,952 B2 US 7,067,952 B2
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`100~----------~~ IOO~ ____ ------~~
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`FIG.9
`FIG.9
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`FIG.lO
`FIG.l0
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`US 7,067,952 B2 US 7,067,952 B2
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`1 1
`STATOR ASSEMBLY MADE FROM A
`STATOR ASSEMBLY MADE FROM A
`MOLDED WEB OF CORE SEGMENTS AND
`MOLDED WEB OF CORE SEGMENTS AND
`MOTOR USING SAME
`MOTOR USING SAME
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`REFERENCE TO EARLIER FILED REFERENCE TO EARLIER FILED
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`APPLICATION APPLICATION
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`The present application is a continuation-in-part of appli(cid:173)The present application is a continuation-in-part of appli(cid:173)
`cation Ser. No. 09/798,511, filed Mar. 2, 2001, now U.S. Pat. cation Ser. No. 091798,511, filed Mar. 2, 2001, now U.S. Pat.
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`No. 7,036,207, and entitled Stator Assembly Made From A No. 7,036,207, and entitled Stator Assembly Made From A
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`Plurality Of Toroidal Core Arc Segments And Motor Using Plurality Of Toroidal Core Arc Segments And Motor Using
`Same, which is hereby incorporated by reference. Same, which is hereby incorporated by reference.
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`FIELD OF THE INVENTION FIELD OF THE INVENTION
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`The present invention relates generally to a stator assem(cid:173)The present invention relates generally to a stator assem(cid:173)
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`bly used in a dynamoelectric machine such as a motor or a bly used in a dynamoelectric machine such as a motor or a
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`generator. It relates particularly to a spindle motor such as generator. It relates particularly to a spindle motor such as
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`used in a hard disc drive, and to the construction and used in a hard disc drive, and to the construction and
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`arrangement of a stator assembly made from a plurality of arrangement of a stator assembly made from a plurality of
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`arc segments. arc segments.
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`BACKGROUND OF THE INVENTION BACKGROUND OF THE INVENTION
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`Computers commonly use disc drives for memory storage Computers commonly use disc drives for memory storage
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`purposes. Disc drives include a stack of one or more purposes. Disc drives include a stack of one or more
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`magnetic discs that rotate and are accessed using a head or magnetic discs that rotate and are accessed using a head or
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`read-write transducer. Typically, a high speed motor such as read-write transducer. Typically, a high speed motor such as
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`a spindle motor is used to rotate the discs. a spindle motor is used to rotate the discs.
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`In conventional spindle motors, stators have been made In conventional spindle motors, stators have been made
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`by laminating together stamped pieces of steel. These by laminating together stamped pieces of steel. These
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`stamped pieces of steel are generally circular in nature, but stamped pieces of steel are generally circular in nature, but
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`also have "poles" extending either inwardly or outwardly, also have "poles" extending either inwardly or outwardly,
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`depending on whether the rotor is on the inside or surrounds depending on whether the rotor is on the inside or surrounds
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`the stator. The stamped pieces are laminated together and the stator. The stamped pieces are laminated together and
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`then coated with insulation. Wire is then wound around the then coated with insulation. Wire is then wound around the
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`poles to form stator windings. poles to form stator windings.
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`An example of a conventional spindle motor 1 is shown An example of a conventional spindle motor 1 is shown
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`in FIG. 1. The motor 1 includes a base 2 which is usually in FIG. 1. The motor 1 includes a base 2 which is usually
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`made from die cast aluminum, a stator 4, a shaft 6, bearings made from die cast aluminum, a stator 4, a shaft 6, bearings
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`7 and a disc support member 8, also referred to as a hub. A 7 and a disc support member 8, also referred to as a hub. A
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`magnet 3 and flux return ring 5 are attached to the disc magnet 3 and flux return ring 5 are attached to the disc
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`support member 8. The stator 4 is separated from the base 2 support member 8. The stator 4 is separated from the base 2
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`using an insulator (not shown) and attached to the base 2 using an insulator (not shown) and attached to the base 2
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`using a glue. Distinct structures are formed in the base 2 and 45 using a glue. Distinct structures are formed in the base 2 and 45
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`the disc support member 8 to accommodate the bearings 7. the disc support member 8 to accommodate the bearings 7.
`One end of the shaft 6 is inserted into the bearing 7 One end of the shaft 6 is inserted into the bearing 7
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`positioned in the base 2 and the other end of the shaft 6 is positioned in the base 2 and the other end of the shaft 6 is
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`placed in the bearing 7 located in the hub 8. A separate placed in the bearing 7 located in the hub 8. A separate
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`electrical connector 9 may also be inserted into the base 2. 50 electrical connector 9 may also be inserted into the base 2. 50
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`Each of these parts must be fixed at predefined tolerances Each of these parts must be fixed at predefined tolerances
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`with respect to one another. Accuracy in these tolerances can with respect to one another. Accuracy in these tolerances can
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`significantly enhance motor performance. significantly enhance motor performance.
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`In operation, the disc stack is placed upon the hub. The In operation, the disc stack is placed upon the hub. The
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`stator windings are selectively energized and interact with 55 stator windings are selectively energized and interact with 55
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`the permanent magnet to cause a defined rotation of the hub. the permanent magnet to cause a defined rotation of the hub.
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`As hub 8 rotates, the head engages in reading or writing As hub 8 rotates, the head engages in reading or writing
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`activities based upon instructions from the CPU in the activities based upon instructions from the CPU in the
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`computer. computer.
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`Manufacturers of disc drives are constantly seeking to Manufacturers of disc drives are constantly seeking to
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`improve the speed with which data can be accessed. To an improve the speed with which data can be accessed. To an
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`extent, this speed depends upon the efficiency of the spindle extent, this speed depends upon the efficiency of the spindle
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`motor, as existing magneto-resistive head technology is motor, as existing magneto-resistive head technology is
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`capable of accessing data at a rate greater than the speed capable of accessing data at a rate greater than the speed
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`offered by the highest speed spindle motor currently in offered by the highest speed spindle motor currently in
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`production. The efficiency of the spindle motor is dependent production. The efficiency of the spindle motor is dependent
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`upon the dimensional consistency or tolerances between the upon the dimensional consistency or tolerances between the
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`2 2
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`various components of the motor. Greater dimensional con(cid:173)various components of the motor. Greater dimensional con(cid:173)
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`sistency between components leads to a smaller gap between sistency between components leads to a smaller gap between
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`the stator 4 and the magnet 3, producing more force, which the stator 4 and the magnet 3, producing more force, which
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`provides more torque and enables faster acceleration and provides more torque and enables faster acceleration and
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`higher rotational speeds. higher rotational speeds.
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`The conventional method of forming stators has a number The conventional method of forming stators has a number
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`of drawbacks. First, most steel is manufactured in rolled of drawbacks. First, most steel is manufactured in rolled
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`sheets and thus has a grain orientation. The grain orientation sheets and thus has a grain orientation. The grain orientation
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`has an effect on the magnetic flux properties of the steel. In has an effect on the magnetic flux properties of the steel. In
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`10 circular stamped pieces of steel, the grain orientation differs 10 circular stamped pieces of steel, the grain orientation differs
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`at different points around the circle. Compared from the at different points around the circle. Compared from the
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`radius line of the circle, the grain orientation is sometimes radius line of the circle, the grain orientation is sometimes
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`aligned along the radius, sometimes transverse to it, and aligned along the radius, sometimes transverse to it, and
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`mostly at a varying angle to the radius. The un-aligned grain mostly at a varying angle to the radius. The un-aligned grain
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`15 structure of conventional stators causes the magnetic flux 15 structure of conventional stators causes the magnetic flux
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`values to differ in parts of the stator, and thus the motor does values to differ in parts of the stator, and thus the motor does
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`not have consistent and uniform torque properties as it not have consistent and uniform torque properties as it
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`rotates. rotates.
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`Another drawback with using circular steel pieces is that, Another drawback with using circular steel pieces is that,
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`20 especially for inward facing poles, it has been difficult to 20 especially for inward facing poles, it has been difficult to
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`wind the wire windings tightly because of the cramped space wind the wire windings tightly because of the cramped space
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`to work inside of the laminated stator core. The cramped to work inside of the laminated stator core. The cramped
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`working space creates a lower limit on the size of the stator working space creates a lower limit on the size of the stator
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`and thus the motor. The limited working space also results and thus the motor. The limited working space also results
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`25 in a low packing density of wire. The packing density of 25 in a low packing density of wire. The packing density of
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`wire coiled around the poles affects the amount of power wire coiled around the poles affects the amount of power
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`generated by the motor. Increasing packing density increases generated by the motor. Increasing packing density increases
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`the power and thus the efficiency of the spindle motor. the power and thus the efficiency of the spindle motor.
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`An important factor in motor design is to reduce stack up An important factor in motor design is to reduce stack up
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`30 tolerances in the motor. Stack up tolerances reduce the 30 tolerances in the motor. Stack up tolerances reduce the
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`overall dimensional consistency between the components. overall dimensional consistency between the components.
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`Stack up tolerances refer to the sum of the variation of all the Stack up tolerances refer to the sum of the variation of all the
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`tolerances of all the parts, as well as the overall tolerance tolerances of all the parts, as well as the overall tolerance
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`that relates to the aligument of the parts relative to one that relates to the aligument of the parts relative to one
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`35 another. One source of stack up tolerances is from the 35 another. One source of stack up tolerances is from the
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`circular stator body. Generally, the thickness of rolled steel circular stator body. Generally, the thickness of rolled steel
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`is not uniform across the width of the roll. Sometimes the is not uniform across the width of the roll. Sometimes the
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`edges are thicker or thinner than the center. In a stator made edges are thicker or thinner than the center. In a stator made
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`from circular stamped pieces, the thicknesses of individual from circular stamped pieces, the thicknesses of individual
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`40 laminations are thus different from one side to the other. 40 laminations are thus different from one side to the other.
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`When stacked together, this creates a stack up tolerance When stacked together, this creates a stack up tolerance
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`problem. Furthermore, the circular stampings leave a lot of problem. Furthermore, the circular stampings leave a lot of
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`wasted steel that is removed and must be recycled or wasted steel that is removed and must be recycled or
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`discarded. discarded.
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`Another important factor in motor design is the lowering Another important factor in motor design is the lowering
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`of the operating temperature of the motor. Increased motor of the operating temperature of the motor. Increased motor
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`temperature affects the electrical efficiency of the motor and temperature affects the electrical efficiency of the motor and
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`bearing life. As temperature increases, resistive loses in wire bearing life. As temperature increases, resistive loses in wire
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`increase, thereby reducing total motor power. Furthermore, increase, thereby reducing total motor power. Furthermore,
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`the Arhennius equation predicts that the failure rate of an the Arhennius equation predicts that the failure rate of an
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`electrical device is exponentially related to its operating electrical device is exponentially related to its operating
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`temperature. The frictional heat generated by bearings temperature. The frictional heat generated by bearings
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`increases with speed. Also, as bearings get hot they expand, increases with speed. Also, as bearings get hot they expand,
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`and the bearing cages get stressed and may deflect, causing and the bearing cages get stressed and may deflect, causing
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`non-uniform rotation, reducing bearing life. This non-uni(cid:173)non-uniform rotation, reducing bearing life. This non-uni(cid:173)
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`form rotation causes a further problem oflimiting the ability form rotation causes a further problem oflimiting the ability
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`of the servo system controlling the read/write heads to of the servo system controlling the read/write heads to
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`follow data tracks on the magnetic media. One drawback follow data tracks on the magnetic media. One drawback
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`with existing motor designs is their limited effective dissi-with existing motor designs is their limited effective dissi-
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`60 pation of the heat, and difficulty in incorporating heat sinks 60 pation of the heat, and difficulty in incorporating heat sinks
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`to aid in heat dissipation. In addition, in current motors the to aid in heat dissipation. In addition, in current motors the
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`operating temperatures generally increase as the size of the operating temperatures generally increase as the size of the
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`motor is decreased. motor is decreased.
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`Manufacturers have established strict requirements on the Manufacturers have established strict requirements on the
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`65 outgassing of materials that are used inside a hard disc drive. 65 outgassing of materials that are used inside a hard disc drive.
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`These requirements are intended to reduce the emission of These requirements are intended to reduce the emission of
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`materials onto the magnetic media or heads during the materials onto the magnetic media or heads during the
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`US 7,067,952 B2
`US 7,067,952 B2
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`3
`3
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`operation of the drive. Of primary concern are glues used to operation of the drive. Of primary concem are glues used to
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`attach components together, varnish used to insulate wire, attach components together, vamish used to insulate wire,
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`and epoxy used to protect steel laminations from oxidation. and epoxy used to protect steel laminations from oxidation.
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`In addition to such outgassed materials, airborne particu(cid:173)In addition to such outgassed materials, airborne particu(cid:173)
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`late in a drive may lead to head damage. Also, airborne late in a drive may lead to head damage. Also, airborne
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`particulates in the disc drive could interfere with signal particulates in the disc drive could interfere with signal
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`transfer between the read/write head and the media. To transfer between the read/write head and the media. To
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`reduce the effects of potential airborne particulate, hard reduce the effects of potential airborne particulate, hard
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`drives are manufactured to exacting clean room standards drives are manufactured to exacting clean room standards
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`and air filters are installed inside of the drive to reduce the 10 and air filters are installed inside of the drive to reduce the 10
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`contamination levels during operation. contamination levels during operation.
`An example of a spindle motor is shown in u.s. Pat. No.
`An example of a spindle motor is shown in U.S. Pat. No.
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`5,6