CA1284813C - Space block control means for dynamoelectric machine - Google Patents

Abstract

SPACE BLOCK CONTROL MEANS FOR DYNAMOELECTRIC MACHINE

Abstract of the Disclosure A control device, such as a U-shaped member including opposingly directed tab projections connected to to upstanding arms of the member may be coupled to a space block of a dynamoelectric machine for limiting motion, especially inward radial motion, of the block. In one embodiment, the space block has a groove for forming a portion of a keyway between the space block and a flange and the tabs of the member are disposed in the keyway radially outward a key which is dimensionally smaller than the groove, so that the tabs abut a sidewall of the groove, thereby limiting motion of the block when the key contacts the tabs.

Description

SPACE BLOCX CONTROL MEANS FOR DYNAMOELECTRIC MACHINE

Back~round oP the Invent~i~n Thi~ invention relate~ to dynamoelectric machines and, more particularly, to control mean~ for limiting ~otlon o~ certain c~mpon~nt~, such A~ ~pace blocks, o~ the ~tator core.
The ~tator core o~ a dynamoelectric ~ach$ne may be described a~ a typically horizontal axially extended annular 6tructur~ that define~ a cylindrical bore in whlch a generally cylindrlcal rotor iB
coaxially positioned for rotation therein~ The annular structure comprise~ ~n axially stacked array o~ a plurality o~ rlat metal lamlnations which are clamped together by axi~lly dlrected forces ln ~lat side by sida relationship between annul~r end rlanges to ~orm an annular wall structure. Extramely high clamplng ~orces are utilized and the de~ined ~tacked laminate structure, when under compression, acquires characteristic~ quite ~imilar to that o~ an integral unitary ~tructure or 601 id cylinder.
In order to dletrlbute the high axial clamping forces in a desired pattarn throughout the laminated -~ , ~284~3~3 ~nnul~r ~tructuxe and to rOrm ventll~t~ng pas~ng3s, radially ~xtendlng arcuatQly spac~d apart ~pace block member~ are inserted ln thQ annul~r stacked array between the annular end ~langes and the annular lamlnate ~tructure ~nd, 1~ deslrQd, di~po~ed between laminations at pr~determln~d axial location~ al4ng ths stator. Addltlonally the end ~lange lncludes a key member which i~ received ln a groove disposad in th~ axial outer ~ur~ace Or ~he axial ~nd-mo~t, or outside, ~pace blocX member~. Th~ groove in th~
space block members i8 oversized with respect to the key member in order to accommodate manu~acturing tolerances. However, ln spitQ o~ large clamping forces employed, it i8 bellev~d that certaln sp~c~
blocks tend to migratQ ~lowly r~dially lnward ~ec~use o~ temperature varlation~ in the stator cora occasioned by start up and shut down c~cle~ and routln~ operation o~ the machine and ~ay eventu~lly detrlmentally compromise the 21ectrical in6ulation of electrical conductor coils or conductor bar~ in the stator core.
Accordingly, it 1~ ~n ob~ect o~ the present invention to provids control means ~or llmiting , migration o~ a ~pace block in a ~tator core o~ a dynamoelectric machine.
It is a further ob~ect o~ the prasent invention to provide control mean~ having a structure whlch can be accommodated by ~xisting spaces available in a stator cor~.
It is yet another ob;ect o~ the present invention to provide control mean~ which can bQ
readily retro~itted onto an existing dynamoelectric machine.

~8~8~3 SU~Y oF T~E..IN~NT.I~
Control ma~n~, ~uch as an open ~ndod U-~haped non-metallic clip me~ber, are ~ltted ov~r one end o~
a spac~ blocX dispo~Qd ln the stator cor~ ~tructure o~ a dynamoelectric mac~line. The open ~nd of the cllp member includ~s inwardly facing tabs which ~it into excess space ln a groov~ disposed in the spac~
block ~or racsiving a key member coupled to an end flange which abuta the space block and wharein the groove is over~ized with respQct to the key me~ber.
Since the keyway arrangement includes a narrower key disposed ln part in a wider groove, tha tabs of the clip occupy exces~ space in the groove o~ the ~pace blocX of th~ keyway and limit transver~e ti.e. radial with respect to the ~tator) motion Or the ~pace block and as~oclated gro3ve with raspect to th~ key.
: The feature~ of tha invention believ~d to b~
nov~l ar~ ~et ~orth wlth par~icularity ln the ~ppended clal~s. Th~ inventlon lt~ , however, both a~ to organization And method o~ operatlon, togather with further ob~ects and advantagss th~reo~, may best be understood by rQ~erence to the detailed description ta~en in connection wlth the accompanylng drawlng.
25 ~rie~ Dçscrip~iQn Q~ the D~wlng Flg. 1 1B a plan view o~ a lamlnation having space ~lock~ coupl~d thereto ~or a dynamoelectric machine.
Fig. 2 is a partial end sectional view o~ ~
dynamoelectric ~achine to which this invention iB
applicable.
Fig. 3 i~ an enlarged view o~ a portion o~ Flg.

2.

~8~8~;3 Fig. 4 is an illustration of one embodiment of control means in accordance with the present lnventlon .
Detailed Description Referring now to Fiy. 1, there is illustrated a sing]"e lamina, or lamination 10. It may be described as having a generally trapezoidal shape with a base surface 11 which is a segm~nt of the circle or outer periphery of an annular stator core structure 12 (Fig. 2). A pair of dovetails 16 is disposed in surface 11. Stator 12 includes a very large number of laminations, having the same general shape as lamination 10, arranged in an axially stacked array in flat side to flat side relationship as well as registered edge to edge relationship to form annular structure 12 (Fig. 2). Layers are staggered so that dovetails 16 are registered while seams between laminations are not registered with those of the adjacent layers. The trapezoidal configuration of lamination 10 also includes a base surface 13, which is also a segment of a circle that generally defines the periphery of the inner cylindrical bore aperture defined by stator 12. Lamination 10 has at least one rectangular section removed to define a cutout 14 between upstanding projections 15 for receiving an electrical conductor. Other sections are removed to define a pair of spaced keyway slots 16 termin~ting at surface 11, which facilitate the assembly as illustrate~ in P'ig. 2.
A space block assembly includes a first and '":',~, ~2~L8~L3 second plurallty o~ spacQ block~ 23 ~nd 24, re~pectiv21y, ~ixedly coupled to lamlnation 10, such as by welding. Spac~ blocko 23 and 24 typic~lly comprise metal h~ving the ~orm o~ n rectangular - 5 601id. Member~ o~ tha flr~t and second plurality o~
space block~ may be identically con~igured except ~or their length. Space block~ 23, belng longar than space block~ 24, extend from surface 11 to surface 13 over upstanding pro~ections 15, while space block~ 24 extend ~rom sur~ce 11 to bottom 6ur~ace 19 or cutout 14. Space block~ 23 and 24 may be ~oreshortened with respect to eur~ac~ 13 and 19, raspectively, and ~urface 11, as shown. When a~sQmbled to ~orm a portion o~ thQ stator core, space blocks 23 and 24 are disposQd substantially radlally with respect to the axi~ Or rotatlon o~ the rotor.
; Referring to Fig. 2, illu~tr~tion o~ a portion o~~thQ axi~l end Or a dynamoel~ctric mach~ne 21 i~
shown. Stator 12 comprise~ a plurality o~ arcuat~ly spaced apart keybar~, only one Or which~ 17, i8 ~hown, which retain ~tacks o~ lamination~ in de~ired annular and axi~l conriguration. An annular ~langa member 22 la disposQd at ~n axlal ~nd of stator 12.
Assembly o~ lamination~ 10 to ~orm an ~nnular ~tator cor~ 12 i~ ~acilitated by tho plur~llty o~
closely arcuately spacQd axially extending key bare 17. Kaybar 17 includ~ ~ key or ~ pro~ection 18 extending outwardly thererrom and axi~lly ther~Along. In cross-~ection, key 13 hae n complement~ry pro~lle to dovetail 16 Or la~ination 10. Each lamination 10 ie positioned to Etraddl0 epaced ad~acent pairs o~ key bar~ 17 oo that ~ 18 o~ key b~r 17 engages one o~ kay slot~ 16 ln ~l284~L3 lamination 10, and ~ 18 o~ An ad~acont k2y bax mata~ with th~ other slot 16 o~ lamination 10. By repet~tion o~ this arrang~mQnt, a larg~ numb~r o~
lamination~ lo are arranged ln a rlat ~tacked axial rQlationship ln pr~ciso r~gi~tration. ~y bAr~ 17 are g~nerally nrranged ln ~ circular row ~o that art~r aasambly, other atack~ Or la~in~tion~ ar~
retained in axlal a~ wall a~ odgawis- r~lation~hip to ~orm annular coro 12.
In stacked reglsterQd relationship with other lamination~ in ~tator 12, cutout ~0ctions 14 Or laminat~on 10 ~or~ axially extending slot~ ~or rece~ving elactrlcal conductor~. Certain groups or packet~ o~ l~minations may b~ ~paced rrom ~d~acQnt -groups or packe~ to provid~ gener~lly radi~lly extending p~ssag~ ~or ~luid cooling ~tator 12. A
thr~ad~d port~on o~ key bar~ 17 extend through ~lange 22. A nut 39 i8 thr~aded on the threadod pro~ection o~ key bar~ 17, nd ~ach nut i8 tlght~n~d ~o that predetermln~d axial, or clamping, ~orce 18 exerted and malntainad on the laminatlons. In practice, an axlnl ~orc~ (which m~y approach 1000 tons ~or lnr~e core structur~s) m~y b~ ~xQrt0d on th- l~mi~at~ core BtructUre o~ ~tator 12. It iQ de~lr~blo to have clamping ~orce~ unl~ormly di~trlbutod ov~r predQtermined areas Or the end ~urrace o~ thQ annular laminate cora structure 12. ono practice employed to attain this result includes u6e 0~ ~paco block~ 23 and 24 ~Fig. 1). In thiM in~ance ~paco block~ 23 and 24 are ~ ~olid m~tal block whlch are disposed between ~lango 22 and the axial end rac~ Or annul~x core ~tructure 12, ~nd thus may be re~erred to ~s outslde space blocks. Additlonal ~pacQ blocka may ~2~3~8~3 also be usad at pr~determin~d axially spaced locations ~long the axial length o~ stator 12 for providlng ~luid coolant pa56age8 through cor~
structure 12.
Th~ large compressivo ~orces on cor~ ~tructur2 12, with resulting high ~rictional ~orce at the flat ' side interfaces betwe~n ad~acent la~inationa, serv~
to retain the lamination~ ln their da~ired po~ition.
Yet, in 8pitQ 0~ thas~ high ~rictlonal and lo compr~siv- ~orcQ~, it has been ~ound that out~ido space block 23 and 24 and lamination 10 (F~g. 1) m~y hav~ ~ tend~ncy to mlgrate 510w~y radially inward towards tha c~ntr~l axia o~ annular cor~ ~tructure 12. Temperature vari~tions in cor~ structure 12 in com~ination with startup and ~hut down cycles o~
machine 21 are believed to generato suf~iciant lateral forc~s to cause ~pac~ blocX ~5~embli~8 to ratchst incrementally radially inward. I~ ~uch inward radial motion i~ not limitad o~ pr~vsnt~d, it may ultimately permit 6pace blocks 23 and 24 nnd/or lamination 10 to contaot ths radially outer portion o~ coil~ 20, l.e. portion o~ coil 20 abutting surface 19 Or ~lot 14 (Fig. 1), and associated electrical insulation. Further inward migration may causa the relatlvely thin edge o~ l~mlnation 10 to comproml~e the electrlcal in~ul~tive integr~ ty o~ tha in~ulation.
One practice employed to restrain spac~ block as~mblie~ ~ro~ moving radially inwardly lncludes arranglng laminatlon 10 80 that dovetail 16 engages the dovetail portion o~ keybar 17. How~ver, even wlth employment Or thi~ dovetall arrangement, it has been ~ound that in certain machin~ oroe~ generated in the ~achin~ are 6urficient to b~nd portions o~
lamination 10 d~flning dovetall 16, r~sulting ~n ultimate radial inward migration o~ epace blocks 23 and 24 and laminatlon 10, ~nd/or cau~ inward migration of both space blocks 23 and 24 ~nd supporting Ad~ acent l~m~nation 10 to which they ar~
welded. Mlgration Or a lamln~tlon and/or ~pace blocks 23 and/or 24 ~ay aventually cause an ~dge o~
the lamlnation ~nd/or ~pac~ block to cut into tha electric~l in6ulation of coil 20 or conductor bar~
dispo6~d ln the stator core 810t~, thereby compromlsing tho electrical insulat~ve integrity o~
tho insulation.
R~ra~rlng to Fig. 3, an snl~rgad vl~w o~ a portion o~ Fig. 2 iB shown. In ord~r to lnsuro further ~gain~t radlal inward migration o~ spac~
block~ 23 ~nd 24, a k~y ~nd k~yw~y arrangem~nt i8 employ~d between outer space block~ 23 and 24 and abuttlng ~l~nge 22. For ease Or understanding and avoidance o~ repetition, th~ ~ollowiny description will refer only to space block 24. It i8 to be under~tood that all comment~ are equally ~ppllcable to spaca blocX 23 except wh~re otherwise noted.
A pair o~ rQgistrablQ keyway groove~ 25 ~nd 26 are ehown dispo~ed in opposed abutting ~urrace~ Or ~pace block 24 nnd ~lanqo 22, re~pectively. When space block ~4 and flange 22 are approprlately assembled, groove 25 o~ ~pace block 2~ ie oppositely regi~tered with groove 26 o~ ~lange 22 to ror~ a keyway between block 24 and rlAngo 22. Wh~n assembled, groovQs 25 and 26 ~ace each other and de~lne a keyway which extends acro~ or bridgee the interfacQ between the abutting surfac~ o~ BpacQ

~2~ 313 block 24 and ~langs 22. A key 27 ia ~itted in groove~ 25 ~nd 26 ~o that lt occupia~ only ~ pnrt Or thQ volume Or gr~ov~ 25, ~nd thereby Qxt~ndo across or brldgQ~ th~ lnt~r~aca ~tween abuttlng ~ur~ace~ o~
- 5 6pacs block 24 and rlange 22. Pre~erably, key 27 will be a portlon o~ sn annular mamber, having a rectangular cross-~eatlon, that i8 rirmly secured in circum~erantlally ~xtending groove 26, ~uch a~ by prQ~ rittlng, ~o that the annul~r ~amber i~
acccomnodat~d during a~s~mbly by groovo 25 ln snch o~
6paCQ blocks 23 (Fig. 1) and 24. ~lt~rnatively, kQy 27 and/or thQ annular member may b~ int~gral ~langa 22.
KQY 27 ha~ A width, i.~. radi~l dimen~ion when disposed in th~ ~eyway, which i8 signi~icantly le~
than th~ wid~h o~ groov~ 25, but ha0 a lQngth, i.~.
axial d~mension when dispos~d ln th~ ~eyway, whlch i8 larga ~nough to str~ddlo at lea~t a portlon o~ groovQ
2s and 26 regardl~a o~ orientatlon o~ k~y 27 within the keywAy. Thi~ ~iz~ ral~tion~hip bRtween key 27 and groova 25 1~ nQcessary to ~acilitate assembly o~
flange 22 and spacs block 24, and to allow ~or potential m1salignment due to build up o~
manufacturing tolerances.
With key 27 residing partly in uach opposite groove 25 and 26 and brldging the inter~ac~ betweQn 6pace block 24 and rlange 22, ~pace block 24 1~ not frse to ~igrat~ without limit in th~ radially inward direction o~ thn arrow of ~ig. 3. A side wall o~
groove 25 in ~pac~ block 24 will ultimat~ly bear against ksy 27 ~hlch will in turn eventually b~ar against A ~idewall o~ groove 26 in ~lang~ 22, thereby preventing ~urther inward radial 61iding movement o~

- 10 - 17Ge 3208 space block 24 after space block 24 has moved a predetermined distance radially inward. However, the initial assembled relationship among grooves 2~ and 26 and key 27 may be such that the above-described motion limiting mechanism may not become effective until a greater than desired inward radial motion of block 24 has occurred.
Since it was decided to maintain uniformity o~ configuration hetween newly assembled dynamoelectric machines and machines which were already in service, a space block movement restraint solution was required which would not only be non-restrictive to current manufacturing practices, but also would be a solution which could be easily applied to in-service machines.
Referring now to Fig. 4, a non-magnetic control means, or clip member 28, comprises a generally U-shaped body having a pair of arms 29 and 30 interconnected by a base wall 31. Tab projections 32 and 33, which project inwardly between arms 29 and 30 towards each other, are coupled to the outer end of arms 29 and 30, respectively. Arms 29 and 30 are flat rectangular members having parallel and coplanar length edges 34 and 35. Tab projections 32 and 33 are ~lush with parallel edges 34 and 35 of clip 28 at the outer ends of arms 29 and 30 and extend a predetermined distance along edges 34 and 35 from transverse edges 36 and 37, respectively, toward base wall 31, and along transverse edges 36 and 37 from edges 35 and 34, respectively, of clip 28. At the same time, tab projections 32 and 33 project from arms 29 and 30, respectively, towards yet spaced from each other. Arms 29 and 30 are ~lexible and ,.'~
` !i~

~2~3~8~3 ~ 17GE 3208 may be pressed towards each other until the tab projections engage each other. By the same token arms 29 and 30 may be pulled further apart from each other to provide a predetermined extended distance between tab projections 32 and 33 without exceeding the elastic modulus of arms 29 and 30, so that arms 29 and 30 return to their pre-stressed configuration when deforming forces are removed.
Returning now to Fig. 3, clip member 28 is 10 mounted on space block 24 so that arms 29 and 30 straddle the radially outer end of space block 24.
Space block 2~ is shown as a relatively narrow rectangular solid metal block which is adapted to be inserted between stator core end flange 22 and core laminations to lie in a radial position against axial end lamination 10 such as illustrated in Fig. 1.
The distance between arms 29 and 30 of clip 28 is about the same as the width of space block 24 so that arms 29 and 30 lie against or contiguously about the sides o~ space block 24 when clip 28 is operatively assembled with space block 24 inserted between arms 29 and 30 in nesting relationship with tab projections 32 and 33 disposed in the unoccupied space between key 27 and the radially outer sidewall o~ groove 25 o~ space block 24.
The actual size of the space between key 27 and the radially outer wall of groove 25 after assembly depends on the machine design and the total tolerance accumulation duriny assembly o~ the machine.
30 Inwardly projecting tabs 32 and 33 of clip 28 are predeterminedly sized to fit into one end of groove 25 and to occupy substantially all the radial extend of groove 25 between key 27 and the radially outer d~

~2~
- 12 - 17Ge 3208 sidewall of groove 25. That is, the extent of tabs 32 and 33 lying along edges 34 and 35 is appropriately configured to provide the required dimension for occupying substantially all the radial extent of groove 25 between key 27 and the radially outer sidewall of groove 25. Likewise, the extent of tabs 32 and 33 lying along edges 3~ and 35 may be appropriately conf:Lgured for providing the desired retrofit orientation for a machine which has been in operation. The length of arms 29 and 30 is predetermined so that tabs 32 and 33 preferably reach the ends of groove 25 in space block 24 at the same time as base wall 31 of clip 28 abuts the radially outer surface of space block 24. After assembly of 15 clip 28 into stator 12, as space block 24 attempts to move radially inward, tabs 32 and 33 are ultimately compressed between key 27 and the radially outer sidewall of groove 25 to prevent any further radial inward motion of space block 24.
In one practice of this invention, clip 28 was fabricated from a resin impregnated glass fabric cloth which was wrapped on a mandrel to form an oversized member having several layers and the general desired final shape of clip 28. After curing, the oversized member was removed from the mandrel and machined to desired dimensions. Suitable resins include polyester resin and flexible epoxy resin. The material selected for clip 28 should maintain its resiliency at temperatures at least up to about 130C
and be inert or relakively inactive with hydrogen when hydrogen i6 used as a cooling fluid for the dynamoelectric machine.
Tabs 32 and 33 of the clip 28 may be pared, such a~ by cutting or abrading, to an appropriate ~ize for fltting whatever exce6s ~pace iB avail~ble between key 27 and th~ radially outer sur~ace o~ groove 25.
When applied according to the pres~nt invention, tab~
5 32 and 33 are sub~ect to co~pre~lvo rOrce~ rather than 6hearing ~orce~ and are ~herefore able to resist very high ratcheting ~orces wlt~out advarsQ
mechanical de~or~ation.
Thus ha~ b~en lllustrated and descrlb~d control means for limiting migration o~ a ~pace block in a 6tator core o~ a dynamoalectric machins, whQrein th~
struCtUrQ Or th~ control m~ans cAn b~ accommodated by exlsting ~pace~ available in a s~ator cor~ and can ba re~dily retroritted onto ~xisting machinss.
While only certain preferred feature~ o~ the invention have baQn shown by way o~ illu~tration, many modi~ic tion~ and changes will occur to those ~killed in the art. It i8 to be understood that the ~ppended claims ara inten~ed to cover all ~uch modi~$cations and changes ~8 ~all within the trua ~pirit ~nd 8COpQ O~ the lnv~ntion.

Claims (12)

1. In a stator core structure of a dynamoelectric machine wherein the core structure comprises an axially stacked array of laminations which form, in assembled relationship, a laminated core structure, and wherein the core structure is retained in its assembled relationship by one of a pair of flanges disposed at each end of the core, and retaining means coupled to said pair of flanges for maintaining clamping forces on the core structure in its assembled relationship, and wherein a space block is inserted between at least one of the flanges and the core structure in abutting surface relationship with the flange for distributing clamping forces imposed on the core structure between said flanges, the improvement which comprises in combination:
each abutting surface of said flange and said space block having a mutually registrable groove disposed therein for forming a keyway between said flange and said space block;
a key member disposable in said keyway and having a width less than the width of the groove of the space block, whereby when the key member is disposed in the keyway there is excess space between the key member and a sidewall of the groove of the space block; and tab means disposed in the groove of the space block for occupying at least a portion of said excess space thereby limiting relative motion between said abutting surfaces.

2. The invention as recited in claim 1, wherein said tab means comprises a non-metallic U-shaped member having tab projections on the upstanding arms of the said U-shape, said U-shaped member being mounted on said space block so that said space block is inserted between the upstanding arms and the tab projections are disposed in the excess space of the groove of the space block.

3. The invention as recited in claim 2, wherein said tab projections are connected to each other through flexible arms which lie along opposite sides of said space block.

4. The invention as recited in claim 2, wherein said tab projections are rectangular members which project into the groove of said space block towards each other from opposite sides of said space block.

5. The invention as recited in claim 4, wherein said tab projections are positioned on the inner ends of the arms of the U-shaped member to project towards each other, the space block being closely fitted within the said U-shaped structure so that the arms thereof are contiguous with said space block.

6. A clip member for mounting on a space block, the space block disposed between a flange and a laminated core structure of a dynamoelectric machine, wherein the space block and the flange abut and each have a mutually registrable groove disposed in their respective abutting surface for forming a keyway therebetween, a key for occupying a portion of said keyway, wherein there is excess space between the key and a sidewall of the groove of said space block when said key is disposed in said keyway, said clip member comprising:
a non-metallic material in U-shaped comprising a pair of arms interconnected by a base member to form a unitary structure; and, a tab coupled to each of said arms and projecting from said arms such that the tabs are disposable in the excess space between said key and a sidewall of the groove in said space block for limiting motion of said space block.

7. The invention as recited in claim 6 wherein said non-metallic material is electrically non-conductive.

8. The invention as recited in claim 7 wherein said electrically non-conductive material is a resin impregnated glass cloth.

9. The invention as recited in claim 8 wherein said resin is an epoxy resin.

10. The invention as recited in claim 8 wherein said resin is a polyester resin.

11. In a dynamoelectric machine, the machine including a stator fabricated from a plurality of axially stacked laminations, flange means disposed at an axial end of said stator, said flange means for maintaining compressive force on said plurality of laminations, and at least one space block disposed between the plurality of laminations and the flange means, said at least one block for transmitting at least a portion of the compressive force between the flange means and the plurality of laminations, said at least one space block and said flange means having a respective groove, the groove of said flange and of said space block mutually registrable for forming a keyway between said flange and said at least one space block, said keyway for receiving keying means, control means comprising:
tab means for disposal in said keyway along with said keying means for limiting inward radial motion of said at least one space block; and support means coupled to said tab means for retaining said tab means within said keyway.

12. The invention as claimed in claim 10 wherein said clip member is generally U-shaped having a pair of cantilevered arms and further wherein said tab includes a projection coupled to each of the pair Claim 12 continued:

of cantilevered arms and directed toward each other so that the arms straddle the space block and each tab projects into said keyway from an opposing direction to maintain said space block in its predetermined position.