United States Patent [19]
`Ulllted States Patent [19]
`Trago et ai.
`Trago et al.
`
`111111
`
`1111111111111111111111111111111111111111111111111111111111111
`US005806169A
`US005806169A
`[11] Patent Number:
`[11] Patent Number:
`[45] Date of Patent:
`[45] Date of Patent:
`
`5,806,169
`5,806,169
`Sep. 15, 1998
`Sep. 15, 1998
`
`,
`
`umi e a .
`
`............................. ..
`
`4,841,190
`4,841,190
`4,922,604
`4,922,604
`5,008,572
`5,008,572
`5,073,735
`5,191,698
`5,331,237
`5,331,237
`5,333,957
`5,333,957
`
`,
`
`6/1989 Matsushita et al. .................... 310/257
`6/1989 Matsushita et al. .................. .. 310/257
`5/1990 Marshall et al. .......................... 29/598
`5/1990 Marshall et al.
`29/598
`4/1991 Marshall et al. .......................... 310/45
`4/1991 Marshall et al.
`310/45
`12/1991 Takagi ................................... 310/43 X
`gakagi
`............................. .. 313/9429);
`3/1993 Sumi et al.
`............................... 29/596
`7/1994 Ichimura
`310/44
`7/1994 Ichimura ................................... 310/44
`8/1994 Yip et al. ................................ 385/484
`8 1994 Y'
`t
`l. .............................. .. 385 484
`/
`1p 6 a
`/
`FOREIGN PATENT DOCUMENTS
`FOREIGN PATENT DOCUMENTS
`0553811
`8/1993 European Pat. Off. .
`8/1993
`European Pat. Off ..
`0553811
`2/1959
`Italy .................................... 264/272.2
`0562146
`0562146 2/1959 Italy .................................. .. 264/2722
`56-094952 7/1981 Japan .
`56-094952
`7/1981
`Japan.
`59-105864
`6/1984
`Japan.
`59-105864 6/1984 Japan .
`59220051 12/1984 Japan .
`59-220051
`12/1984
`Japan.
`1/1995
`Japan.
`31120
`31120
`1/1995 Japan .
`WO 91/09441
`6/1991
`WIPO.
`W0 91 09441
`6 1991 WIPO .
`/
`/
`Primary Examiner—Carl E. Hall
`Primary Examiner-Carl E. Hall
`Attorney, Agent, or Firm-Leydig, Voit & Mayer
`Attorney, Agent, or Firm—Leydig, Voit & Mayer
`[57]
`ABSTRACT
`ABSTRACT
`[57]
`
`[54]
`METHOD OF FABRICATING AN INJECTED
`[54] METHOD OF FABRICATING AN INJECTEI)
`MOLDED MOTOR ASSEMBLY
`MOLDED MOTOR ASSEMBLY
`
`[76] Inventors: Bradley A_ Trago, 922 Cerasus Dr”
`Inventors: Bradley A. Trago, 922 Cerasus Dr.,
`[76]
`Rockford, Ill. 61108; Edward J.
`ggillifezrdl’llélvsggging‘gagg'
`Byrnes, 116 Woodland Ct., #1D,
`’
`.
`"
`,
`’
`Carpentersville, Ill. 60110; Griff D.
`Carpentersville, Ill. 60110; Grl?' D.
`Neal, 2600 N. Southport Ave., Unit 31,
`Neal, 2600 N. Southport Ave., Unit 31,
`Chicago, Ill. 60614
`Chlcago’ In‘ 60614
`
`_
`
`Appl. No.: 415,639
`[21]
`[21] APPI- NO-I 415,639
`.
`_
`Filed:
`Apr. 3, 1995
`[22]
`[22] Flled-
`AP“ 3’ 1995
`Int. CI.6
`..................................................... H02K 15/04
`[51]
`[51] Int. Cl.6 ................................................... .. H02K 15/04
`U.S. CI. ........................... 29/596; 264/272.2; 310/42;
`[52]
`[52] US. Cl. ......................... .. 29/596; 264/2722; 310/42,
`310/43; 310/90
`310/43; 310/90
`[58] Field of Search ...................... .. 29/596, 598; 310/42,
`Field of Search ........................ 29/596, 598; 310/42,
`[58]
`310/43, 90, 71; 264/272.2, 272.19
`310/43, 90, 71; 264/2722, 272.19
`
`[56]
`[56]
`
`References Cited
`References Cited
`U.S. PATENT DOCUMENTS
`U.S. PATENT DOCUMENTS
`
`2,916,642 12/1959 Macks ....................................... 310/90
`Macks ..................................... ..
`7/1962 Graham et al. .
`3,046,604
`7/1962 Gr‘fhan} et al' '
`370467604
`3,156,076 11/1964 Origoni et al.
`........................... 29/596
`19min“ et a1‘
`6/1966 Turk ........................................ 310/261
`3,258,624
`""" "
`3/1969
`31O/9O
`3’433’986
`3/1969 Arutunoff .................................. 310/90
`3,433,986
`3/1977 Tanaka et
`29/596
`4’015’154
`3/1977 Tanaka et al. ............................ 29/596
`4,015,154
`6/1977 Chai et aL
`31O/49
`4ZO29Z977
`6/1977 Chai et al. ................................ 310/49
`4,029,977
`4/1980 Binns er a1, __
`310/90
`4,200,344
`4/1980 Binns et al.
`.............................. 310/90
`4,200,344
`5/1983 Isaacson .................................... 310/90
`4,382,199
`5/1983 Isaacson . . . . . . . .
`. . . . .. 310/90
`4,382,199
`8/1985 Kawada et al. ......................... 310/217
`4,538,084
`8/1985 Kawada et al
`4,538,084
`310/217
`4,549,105 10/1985 Yamamoto et al.
`.................. 310/43 X
`4,549,105 10/1985 Yamamoto et a1-
`- 310/43 X
`4,626,725 12/1986 Kawada et al. ........................... 310/89
`4,626,725 12/1986 Kawada et al. ......................... .. 310/89
`4,696,631
`9/1987 Nitt ....................................... 29/596 X
`""""""""""""""""""" " 29/5519
`4,712,028 12/1987 Horber ...................................... 310/49
`4,713,570 12/1987 Mastromattei
`310/154
`4,713,570 12/1987 Mastromattei .......................... 310/154
`4,763,034
`8/1988 Gamble ................................... 310/181
`4,763,034
`8/1988 Gamble ....... ..
`310/181
`4,781,610 11/1988 Mercer ...................................... 310/71
`4,781,610 11/1988 Mercer ..
`.... .. 310/71
`
`41
`
`An electrical motor and the process for forming that motor
`An electrical motor and the process for forming that motor
`utilizes injection molding techniques to unitize the stator
`utilizes in'ection moldin techni ues to unitiZe the stator
`J
`g
`_ q
`_
`_
`assembly. The stator assembly includes a stator lamination
`assembly. The stator assembly includes a stator lamination
`stack and preferably a metal front end cap which is secured
`Stack and preferably a metal front end Cap
`is Secured
`to the lamination stack after the lamination stack is insulated
`to the lamination stack after the lamination stack is insulated
`and wound. The windings are terminated at a plurality of
`and Wound. The Windings are terminated at a plurality of
`conductive pins fusion welded to the terminating ends of the
`conductive pins fusion Welded to the terminating ends of the
`windings. The stator assembly with front end cap in place is
`Windings. The stator assembly With front end cap in place is
`positioned in an injection molding die. Pressure is applied to
`positioned in an injection'molding die. Pressure is applied to
`the die, and molten plastic is injected under pressure to fill
`the die, and molten plastic is 1n]ected under pressure to ?ll
`voids in the stator assembly, and also to form a plastic mass
`voids in the stator assembly, and also to form a plastic mass
`which will serve as the rear end cap. The rear end cap is also
`Which Will serve as the rear end cap. The rear end cap is also
`molded with a connector portion which fixes the conductive
`molded With a connector portion Which ?xes the conductive
`pins in place as a part of the connector. A bore formed in the
`pins in place as a part of the Connecton Abore formed in the
`stator assembly provides mounting surfaces for bearings on
`stator assembly provides mounting surfaces for bearings on
`a rotor assembly.
`a rotor assembly‘
`
`28 Claims, 10 Drawing Sheets
`28 Claims, 10 Drawing Sheets
`
`951!_1:~~
`
`25
`
`31
`
`NIDEC and HONDA - Ex. 1015
`Nidec Corporation and American Honda
`Motor Co., Inc. - Petitioners
`
`1
`
`

`

`u.s. Patent
`U.S. Patent
`
`Sep. 15,1998
`Sep. 15, 1998
`
`Sheet 1 0f 10
`Sheet 1 of 10
`
`5,806,169
`5,806,169
`
`25_nllll.
`
`26
`
`I
`
`20
`
`,c~ 2
`
`2
`
`

`

`u.s. Patent
`U.S. Patent
`
`Sep. 15, 1998
`Sep. 15, 1998
`
`Sheet 2 of 10
`
`5,806,169
`
`100"",
`
`H'EL.P .r?;tlT()~
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`
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`• ,. ~ FRONT - "(cid:173)
`..... - - - _ ....
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`113
`
`115
`
`116
`
`3
`
`

`

`u.s. Patent
`U.S. Patent
`
`Sep. 15,1998
`Sep. 15, 1998
`
`Sheet 3 0f 10
`Sheet 3 of 10
`
`5,806,169
`5,806,169
`
`52
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`
`

`

`u.s. Patent
`U.S. Patent
`
`Sep. 15,1998
`Sep. 15, 1998
`
`Sheet 4 of 10
`Sheet 4 0f 10
`
`5,806,169
`5,806,169
`
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`
`

`

`u.s. Patent
`U.S. Patent
`
`Sep. 15,1998
`Sep. 15, 1998
`
`Sheet 5 of 10
`Sheet 5 0f 10
`
`5,806,169
`5,806,169
`
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`

`

`u.s. Patent
`U.S. Patent
`
`Sep. IS, 1998
`Sep. 15,1998
`
`Sheet 6 0f 10
`Sheet 6 of 10
`
`5,806,169
`5,806,169
`
`95
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`
`

`

`u.s. Patent
`U.S. Patent
`
`Sep. 15, 1998
`Sep. 15, 1998
`
`Sheet 7 of 10
`Sheet 7 0f 10
`
`5,806,169
`5,806,169
`
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`

`u.s. Patent
`U.S. Patent
`
`Sep. 15,1998
`Sep. 15, 1998
`
`Sheet 8 of 10
`Sheet 8 0f 10
`
`5,806,169
`5,806,169
`
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`

`u.s. Patent
`U.S. Patent
`
`Sep. 15,1998
`Sep. 15, 1998
`
`Sheet 9 0f 10
`Sheet 9 of 10
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`5,806,169
`5,806,169
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`

`u.s. Patent
`U.S. Patent
`
`Sep. 15,1998
`Sep. 15, 1998
`
`Sheet 10 0f 10
`Sheet 10 of 10
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`5,806,169
`5,806,169
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`

`5,806,169
`5,806,169
`
`1
`1
`METHOD OF FABRICATING AN INJECTED
`METHOD OF FABRICATING AN INJECTED
`MOLDED MOTOR ASSEMBLY
`MOLDED MOTOR ASSEMBLY
`
`BACKGROUND OF THE INVENTION
`BACKGROUND OF THE INVENTION
`
`5
`
`2
`2
`'604 references, an insulator having connectors is seated
`’604 references, an insulator having connectors is seated
`against the rear end of the stator lamination stack. The
`against the rear end of the stator lamination stack. The
`terminating ends of the stator Windings are brought out to the
`terminating ends of the stator windings are brought out to the
`connectors, and a printed circuit board is con?gured to plug
`connectors, and a printed circuit board is configured to plug
`into connectors, establishing electrical continuity betWeen
`into connectors, establishing electrical continuity between
`the stator windings and conductive traces on the printed
`the stator Windings and conductive traces on the printed
`circuit. A second connector having conductive pins electri
`circuit. A second connector having conductive pins electri(cid:173)
`cally connected to the conductive traces on the printed
`cally connected to the conductive traces on the printed
`circuit, is provided in conjunction With the printed circuit
`circuit, is provided in conjunction with the printed circuit
`10 board to accommodate remote access to the stator windings
`board to accommodate remote access to the stator Windings
`10
`by way of a complementary external connector. In this way,
`by Way of a complementary external connector. In this Way,
`external signals are readily connected to the stator Windings
`external signals are readily connected to the stator windings
`for controlling the motor operation.
`for controlling the motor operation.
`This second connector is nested within the rear stator end
`This second connector is nested Within the rear stator end
`cap. As previously described, both end caps are attached to
`cap. As previously described, both end caps are attached to
`the lamination stack by means of several through bolts,
`the lamination stack by means of several through bolts,
`before the potting compound is applied. To prevent any
`before the potting compound is applied. To prevent any
`potting compound from leaking betWeen the rear end cap
`potting compound from leaking between the rear end cap
`and the second connector, a sealing means is provided
`and the second connector, a sealing means is provided
`20 around the second connector. Although the aforementioned
`around the second connector. Although the aforementioned
`20
`structure provides an effective means for connecting exter(cid:173)
`structure provides an effective means for connecting exter
`nal motor drive signals to the stator Windings, a simpler and
`nal motor drive signals to the stator windings, a simpler and
`therefore more cost-effective solution is desired.
`therefore more cost-effective solution is desired.
`In short, improvements are sought which will more effi-
`In short, improvements are sought Which Will more ef?
`25
`ciently address the aspects described above, While maintain
`25 ciently address the aspects described above, while maintain(cid:173)
`ing the bene?ts and advantages in the motor assembly and
`ing the benefits and advantages in the motor assembly and
`method as described in the '572 and '604 references.
`method as described in the ’572 and ’604 references.
`
`1. Field of the Art
`1. Field of the Art
`The present invention relates to electric motors, and more
`The present invention relates to electric motors, and more
`particularly to a fabrication method and related assembly of
`particularly to a fabrication method and related assembly of
`potted electrical motors.
`potted electrical motors.
`2. Discussion of the Related Art
`2. Discussion of the Related Art
`U.S. Pat. Nos. 4,922,604 to Marshall et aI. and 5,008,572
`US. Pat. Nos. 4,922,604 to Marshall et al. and 5,008,572
`to Marshall et aI., both assigned to an assignee of the present
`to Marshall et al., both assigned to an assignee of the present
`invention and hereby incorporated by reference, describe an
`invention and hereby incorporated by reference, describe an
`electrical motor and fabrication method for achieving pre
`electrical motor and fabrication method for achieving pre(cid:173)
`cise bearing registration of an internally disposed rotor
`cise bearing registration of an internally disposed rotor 15
`15
`assembly. As described more fully in the aforementioned
`assembly. As described more fully in the aforementioned
`references, an electrical motor comprising stator and rotor
`references, an electrical motor comprising stator and rotor
`assemblies is fabricated by utiliZing a potting compound to
`assemblies is fabricated by utilizing a potting compound to
`both unitiZe the stator assembly and provide improved
`both unitize the stator assembly and provide improved
`thermal characteristics.
`thermal characteristics.
`More particularly, the stator assembly is formed from a
`More particularly, the stator assembly is formed from a
`stack of stator laminations having inWardly projecting poles
`stack of stator laminations having inwardly projecting poles
`that define the walls of an unfinished internal chamber for
`that de?ne the Walls of an un?nished internal chamber for
`housing a rotor assembly. Through-bolts attach front and
`housing a rotor assembly. Through-bolts attach front and
`rear aluminum end caps to the lamination stack, and this
`rear aluminum end caps to the lamination stack, and this
`entire stator assembly is potted to unitiZe the lamination
`entire stator assembly is potted to unitize the lamination
`stack and ?ll voids betWeen the stator poles With potting
`stack and fill voids between the stator poles with potting
`compound. The internal chamber is then ?nished by machin
`compound. The internal chamber is then finished by machin(cid:173)
`ing a continuous, cylindrical bore substantially coincident
`ing a continuous, cylindrical bore substantially coincident
`30
`With the sideWalls de?ned by the inWardly projecting stator
`with the sidewalls defined by the inwardly projecting stator 30
`poles. Precision registration of the rotor assembly is
`poles. Precision registration of the rotor assembly is
`achieved by aligning end bearings on the rotor shaft With
`achieved by aligning end bearings on the rotor shaft with
`internal receiving surfaces machined in the stator end caps;
`internal receiving surfaces machined in the stator end caps;
`the receiving surfaces being part of the cylindrical bore.
`the receiving surfaces being part of the cylindrical bore.
`35
`While the motor and fabrication method described in the 35
`While the motor and fabrication method described in the
`'604 and '572 references achieve substantial advances over
`’604 and ’572 references achieve substantial advances over
`the prior art, further improvements are still desired. In this
`the prior art, further improvements are still desired. In this
`regard, various features of the assembly and method
`regard, various features of the assembly and method
`described in the '604 and '572 references were identified for 40
`described in the ’604 and ’572 references Were identi?ed for
`40
`improvement.
`improvement.
`One area sought to be improved relates to the potting of
`One area sought to be improved relates to the potting of
`the stator assembly. Speci?cally, it has been determined
`the stator assembly. Specifically, it has been determined
`empirically that a double cure cycle is desired for the potting
`empirically that a double cure cycle is desired for the potting
`compound; the second cure cycle improves the rigidity of
`compound; the second cure cycle improves the rigidity of
`the stator assembly, thereby yielding more ef?cient opera
`the stator assembly, thereby yielding more efficient opera(cid:173)
`tion over the life of the motor. When only a single cure cycle
`tion over the life of the motor. When only a single cure cycle
`is employed it has been found that, after a period of use, the
`is employed it has been found that, after a period of use, the
`rotor assembly occasionally locks Within the stator
`rotor assembly occasionally locks within the stator
`assembly, thereby limiting the useful life of the motor.
`assembly, thereby limiting the useful life of the motor. 50
`Adding a second cure cycle, however, undesirably increases
`Adding a second cure cycle, hoWever, undesirably increases
`manufacturing costs.
`manufacturing costs.
`A related aspect sought to be improved is the removal of
`A related aspect sought to be improved is the removal of
`air pockets formed Within the potting compound. As dis
`air pockets formed within the potting compound. As dis(cid:173)
`cussed in the '572 and '604 references, air is a poor thermal 55
`cussed in the ’572 and ’604 references, air is a poor thermal
`55
`conductor. Filling the otherwise open space between the
`conductor. Filling the otherWise open space betWeen the
`stator poles With potting compound, improves thermal con
`stator poles with potting compound, improves thermal con(cid:173)
`ductivity and, accordingly, improves dissipation of the heat
`ductivity and, accordingly, improves dissipation of the heat
`developed within the motor. The process used in potting the
`developed Within the motor. The process used in potting the
`stator assembly, however, is known to leave an air pocket 60
`stator assembly, hoWever, is knoWn to leave an air pocket
`60
`under the rear end cap. This impedes the flow of heat from
`under the rear end cap. This impedes the How of heat from
`the rear end cap. Therefore, further improvements in the
`the rear end cap. Therefore, further improvements in the
`thermal characteristics of the motor assembly are sought by
`thermal characteristics of the motor assembly are sought by
`eliminating the air pocket.
`eliminating the air pocket.
`Another area sought to be further improved relates to 65
`Another area sought to be further improved relates to
`65
`providing external electrical connections to the stator wind(cid:173)
`providing external electrical connections to the stator Wind
`ings Within the motor assembly. As described in the ’572 and
`ings within the motor assembly. As described in the '572 and
`
`SUMMARY OF THE INVENTION
`SUMMARY OF THE INVENTION
`
`In vieW of the foregoing, it is a primary aim of the present
`In view of the foregoing, it is a primary aim of the present
`invention to simplify and, thereby, achieve a loWer cost
`invention to simplify and, thereby, achieve a lower cost
`motor assembly and fabrication method, than that presently
`motor assembly and fabrication method, than that presently
`known.
`knoWn.
`Another object of the present invention is to provide an
`Another object of the present invention is to provide an
`electrical motor assembly having improved thermal charac
`electrical motor assembly having improved thermal charac(cid:173)
`teristics.
`teristics.
`In more detail, it is an object of the present invention to
`In more detail, it is an object of the present invention to
`eliminate the small air gap betWeen the potted Windings and
`eliminate the small air gap between the potted windings and
`the metal of the aluminum end cap. In even greater detail, an
`the metal of the aluminum end cap. In even greater detail, an
`object of the present invention is to provide high dielectric
`object of the present invention is to provide high dielectric
`paths of good thermal conductivity betWeen the electrical
`paths of good thermal conductivity between the electrical
`conductor and pole structure and the exterior of the motor,
`conductor and pole structure and the exterior of the motor,
`in order to increase the capacity of the motor to dissipate
`in order to increase the capacity of the motor to dissipate
`45
`45 heat.
`heat.
`Another object of the present invention is to provide an
`Another object of the present invention is to provide an
`electrical motor fabrication method that simplifies the
`electrical motor fabrication method that simpli?es the
`method previously knoWn and used by eliminating the cost
`method previously known and used by eliminating the cost
`and time demanded by a second potting compound cure
`and time demanded by a second potting compound cure
`cycle, While maintaining the structural integrity of the ?nal
`cycle, while maintaining the structural integrity of the final
`motor assembly.
`motor assembly.
`Still another object of the present invention is to provide
`Still another object of the present invention is to provide
`an electrical motor assembly having a simplified and thus
`an electrical motor assembly having a simpli?ed and thus
`improved electrical connection between the internal stator
`improved electrical connection betWeen the internal stator
`windings and an external connector.
`Windings and an external connector.
`Additional objects, advantages and other novel features of
`Additional objects, advantages and other novel features of
`the invention will be set forth in part in the description that
`the invention Will be set forth in part in the description that
`follows and in part will become apparent to those skilled in
`folloWs and in part Will become apparent to those skilled in
`the art upon examination of the following or may be learned
`the art upon examination of the folloWing or may be learned
`With the practice of the invention. The objects and advan
`with the practice of the invention. The objects and advan(cid:173)
`tages of the invention may be realiZed and obtained by
`tages of the invention may be realized and obtained by
`means of the instrumentalities and combinations particularly
`means of the instrumentalities and combinations particularly
`pointed out in the appended claims.
`pointed out in the appended claims.
`To achieve the foregoing and other objects, one aspect of
`To achieve the foregoing and other objects, one aspect of
`the present invention is directed to a method of producing an
`the present invention is directed to a method of producing an
`electrical motor, wherein an intermediate or unfinished
`electrical motor, Wherein an intermediate or un?nished
`
`12
`
`

`

`5,806,169
`5,806,169
`
`4
`4
`FIG. 6 is an elevational view of an individual stator
`FIG. 6 is an elevational vieW of an individual stator
`lamination, illustrating the inWardly directed stator poles
`lamination, illustrating the inwardly directed stator poles
`and pole teeth;
`and pole teeth;
`FIG. 7 is a perspective view showing an assembled stator
`FIG. 7 is a perspective vieW shoWing an assembled stator
`lamination stack made up of individual laminations as
`lamination stack made up of individual laminations as
`illustrated in FIG. 6;
`illustrated in FIG. 6;
`FIG. 8 is a perspective view of the front end of the stator
`FIG. 8 is a perspective vieW of the front end of the stator
`lamination stack of FIG. 7 with insulators and stator wind(cid:173)
`lamination stack of FIG. 7 With insulators and stator Wind
`ings in place;
`ings in place;
`FIG. 9 is the cut-away view as illustrated by arrows in
`FIG. 9 is the cut-aWay vieW as illustrated by arroWs in
`FIG. 6, illustrating a Wound stator assembly Within the caps
`FIG. 6, illustrating a wound stator assembly within the caps
`and connector in place;
`and connector in place;
`FIG. 10 is a perspective view of the rear end of the
`FIG. 10 is a perspective vieW of the rear end of the
`un?nished stator assembly, shoWing the insulators, stator
`unfinished stator assembly, showing the insulators, stator
`Windings, and matrix of connector pins in place;
`windings, and matrix of connector pins in place;
`FIG. 11 is a partial view illustrating the matrix of con(cid:173)
`FIG. 11 is a partial vieW illustrating the matrix of con
`nector pins as disposed in relation to the stator lamination
`nector pins as disposed in relation to the stator lamination
`stack;
`stack;
`FIG. 12 is a partial view illustrating the partially com(cid:173)
`FIG. 12 is a partial vieW illustrating the partially com
`pleted stator assembly of FIG. 9 after injection molding;
`pleted stator assembly of FIG. 9 after injection molding;
`FIG. 13 is a view similar to FIG. 12 illustrating the
`FIG. 13 is a vieW similar to FIG. 12 illustrating the
`injection molded assembly after it has been machined and is
`injection molded assembly after it has been machined and is
`thus ready for insertion of the rotor assembly;
`thus ready for insertion of the rotor assembly;
`FIG. 14 is a side elevational view showing a mold fixture
`FIG. 14 is a side elevational vieW shoWing a mold ?xture
`used in fabricating the motor assembly of the present
`used in fabricating the motor assembly of the present
`invention;
`invention;
`FIG. 15 is a perspective view with a partial cut-away of
`FIG. 15 is a perspective vieW With a partial cut-aWay of
`the mold fixture shown in FIG. 14;
`the mold ?xture shoWn in FIG. 14;
`FIG. 16 is a partly broken away side view, and FIG. 17 is
`FIG. 16 is a partly broken aWay side vieW, and FIG. 17 is
`an axial section taken along the line 17-17 of FIG. 16,
`an axial section taken along the line 17—17 of FIG. 16,
`respectively, shoWing an alternative construction of motor
`respectively, showing an alternative construction of motor
`adapted for practice of the present invention;
`adapted for practice of the present invention;
`FIG. 18 is an elevational view of a rotor assembly for the
`FIG. 18 is an elevational vieW of a rotor assembly for the
`motor of FIGS. 16 and 17; and
`motor of FIGS. 16 and 17; and
`FIGS. 19 and 20 are an elevational cross section and an
`FIGS. 19 and 20 are an elevational cross section and an
`axial cross section taken along the line 20-20 at FIG. 19,
`axial cross section taken along the line 20—20 at FIG. 19,
`respectively, shoWing a permanent magnet motor adapted
`respectively, showing a permanent magnet motor adapted
`for practice of the present invention.
`for practice of the present invention.
`Reference will now be made in detail to various presently
`Reference Will noW be made in detail to various presently
`preferred embodiments of the invention, examples of Which
`preferred embodiments of the invention, examples of which
`are illustrated in the accompanying draWings.
`are illustrated in the accompanying drawings.
`
`3
`3
`stator assembly is formed by compiling a stack of stator
`stator assembly is formed by compiling a stack of stator
`laminations and stator Windings. The intermediate stator
`laminations and stator windings. The intermediate stator
`assembly is then placed into a mold, and molten plastic is
`assembly is then placed into a mold, and molten plastic is
`injected under pressure into the mold, Whereby the molten
`injected under pressure into the mold, whereby the molten
`plastic is forced into and ?lls interior voids betWeen poles of
`plastic is forced into and fills interior voids between poles of 5
`the intermediate stator assembly. The molten plastic also
`the intermediate stator assembly. The molten plastic also
`forms a rear end cap for the stator assembly. The plastic used
`forms a rear end cap for the stator assembly. The plastic used
`in this invention may be any thermoplastically processible
`in this invention may be any thermoplastically processible
`resin, or blends of such resins. The resin may optionally
`resin, or blends of such resins. The resin may optionally
`include additives such as flame retardants, reinforcements, 10
`include additives such as ?ame retardants, reinforcements,
`10
`colored pigments, ?llers, plasticiZers, heat or light stabiliZ
`colored pigments, fillers, plasticizers, heat or light stabiliz(cid:173)
`ers. Next, a continuous bore is machined through the center
`ers. Next, a continuous bore is machined through the center
`of the molded stator assembly to produce a concentric bore
`of the molded stator assembly to produce a concentric bore
`for housing a rotor assembly; the bore also providing
`for housing a rotor assembly; the bore also providing
`mounting surfaces for receiving rotor assembly bearings.
`mounting surfaces for receiving rotor assembly bearings.
`15
`Finally, the rotor assembly is mounted into the stator assem- 15
`Finally, the rotor assembly is mounted into the stator assem
`bly by inserting the rotor assembly into the continuous bore
`bly by inserting the rotor assembly into the continuous bore
`and engaging the rotor bearings With the mounting surfaces.
`and engaging the rotor bearings with the mounting surfaces.
`Arelated aspect of the present invention is directed to the
`A related aspect of the present invention is directed to the
`injection molded electrical motor assembly, Which includes
`injection molded electrical motor assembly, which includes
`a rotor assembly having a central rotor portion on a rotor 20
`a rotor assembly having a central rotor portion on a rotor
`shaft, and a rotor bearing disposed near each end of the rotor
`shaft, and a rotor bearing disposed near each end of the rotor
`shaft. A unitary stator assembly includes a stator lamination
`shaft. Aunitary stator assembly includes a stator lamination
`stack Which forms stator poles that carry stator Windings,
`stack which forms stator poles that carry stator windings,
`and front and rear end caps. The stator poles and Windings
`and front and rear end caps. The stator poles and windings
`are substantially encapsulated by an injection molded plastic
`are substantially encapsulated by an injection molded plastic 25
`25
`mass, which fills the space between the stator poles. The
`mass, Which ?lls the space betWeen the stator poles. The
`molded plastic also integrally forms the rear end cap. A
`molded plastic also integrally forms the rear end cap. A
`continuous bore formed in the stator assembly through the
`continuous bore formed in the stator assembly through the
`front end cap, the stator lamination stack, and the rear end
`front end cap, the stator lamination stack, and the rear end
`cap, forms mounting surfaces in the end caps for receiving
`cap, forms mounting surfaces in the end caps for receiving 30
`the rotor bearings; the rotor assembly being carried Within
`the rotor bearings; the rot