US2781165A

US2781165A - Motor driven fan and method of assembling the components thereof

Info

Publication number: US2781165A
Application number: US397989A
Authority: US
Inventors: Theodor H Troller
Original assignee: Joy Manufacturing Co
Current assignee: Joy Manufacturing Co
Priority date: 1953-12-14
Filing date: 1953-12-14
Publication date: 1957-02-12
Anticipated expiration: 1974-02-12

Description

Feb. 12, 1957 T H. TROLLE 2,781,165

MOTOR DRIVEN FAN AND METHOD ASEMBLING THE COMPONENTS THEREOF Original Filed Oct. 50, 1947 ,4; 4* diififiiy.

MGTOR DRIVEN FAN AND METHOD OFASSEM- BLING THE COMPONENTS- THEREfiF Theodor H. Troller, Portal, Ariz assignor to Joy Manufacturing Company, a corporation of Penney? 'ania Continuation of forfeited application Serial No; 783,147, October 30, 1947'. This application December 14, 1953, Serial No. 397,989

Claims. (Cl. 230-417) This invention relates in general to an axial flow fan and a drive therefor, and more particularly to an arrangement of a fan driving motor within a fan and drivehouslug-also called a fan and motor casing-for supporting a fan and the driving motor therefor, so that the fan may runwith close tipclearance between the same and the housing. From another aspect, the invention relates to improved'methods of effecting coaxial assembly of fansinthe fan chambers of fan and motor casings.

The. etficiency of axial flow fans of the vane-axial typeis greatly influenced by the clearance between the tips of the: fan blades and theinner wall of the fan chamber, and Where this clearance can be kept down to a few thousandths of an inch, highly advantageous results maybe obtained. In the volume production of small fans utilizing motors'built by volume production methods, there islittle probability of the finding of a peripheral motorsurface so perfectly coaxial with the axis of rotation of the fan supporting and driving shaft as to permit, through the cooperation of such surface with a matingly shaped internal surface on the fan and motor casing, the desired centering of the fan in the fan chamber of the fan casing. Accordingly, a manufacturer of large numbers of fans, desiring to apply volume production methods, may be facedv with serious increases in expense and additional manufacturing operations if customary methods used on larger and more expensive fans must be applied toeffect minimization and uniformity of clearance between the fan blades and fan casing; walls. If, on. the other hand, there can be. provided some method whereby the shaft of a motor which does.- not have unduly large clearances at its shaft bearings can, be precisely centered with respect to the fan and motor casing, and particularly with respect to the'fan chamber of such a casing and. especially if there be employed monobloc fan and motor casings so that serious distortion in use is not likely to be encountered? andif then simple means adequate tomaintainthe-coax-ial. relationcan be employed, all without having to machine ainotor surfacestrictlycoaxial. with. axis of shaft rotation,.. a very desirable result may be obtained.

' It is an object of this. invention to provide an. improved. axial flow fan. It is another object to provide, an improved axial flow fan of the type in which the motor is. carriedby the fan andlmotor casing, It. is a further object.

to. provide an improved axial flow fan having a driving motor carried by a fan and motor casing and employing improved means for maintaining the motor shaftand. consequently the fan-coaxial with the internal Wall of the fan. chamber. It is still another object to provide an improved axial ilow fan having improved means involving no special machining of surfaces of. revolution on the motor casing, for maintaining the fan driving motor with its shaft in coaxial relation with the inner wall of the fan chamber of a fan and motor casing in such. manner thatthe tip clearance. between the fan and the wallet its chamberiirthe casing may be maintained at'a smallminif: mum; It' is still another object to provide an improved flow fan'in which the driving motor is carried by the atent O A 2,7 81,155 rist niedrea. 12, 1957,

2 fan and motor casing in which. the centeiing of the. motor shaft'with respect to the fan chamber is accomplished en tirely by means coacting with a radially extending surface, as distinguished from a surface of revolution, either on the motor or on the fan and motor casing. It is still a further object of the invention to provide an improvedmethod for the volume production and precision assembly of axial iiow fans.

Other objects and a fuller understandingofthe invention may be had by referring to the following description and" claims, taken in conjunction with the accompanying drawing, in which: 7 V v Fig. l is a longitudinal section'through a fan and motor casingmounted on'a jig used in efifecting assembly,

"Fig. '2 is a corresponding view, with a fan driving motor received inthe man and motor casing and fixed in coaxial. elation to the latter. 7 j o o v Fig; 3- is a view of a motor as the same appears before being placed in the jig.

Fig. 4' is an end view of the motor of Fig; 3, showing the positioning means. 1

Fig. 5' is a central longitudinal section through a completeaxlal flow fan, assembled and held together according to. the method of Figs. 1 and 2, a fan rotor having been mounted upon the motor shaft.

In. a preferred embodiment of the invention, from its apparatus: aspect, there is provided a fan and motor casing, desirably of monobloc construction, and compris-; ing an outer annular wall one portion of which bounds a fan chamber and a longitudinally difierent portionof which has aj plurality of circumferentially spaced vanes extendin-g inwardly from it and desirably integrally connected with it, said vanes being connected at their radially inner ends by connecting means comprising a radially inwardly directed annular Wall portion presenting a transversely eittendingsurface. Such connection may also comprise an inner annular wall generally concentric Wit-h the outer an-1 nul-ar wall to which the inner ends of the'vanes are desirably directly and integrally connected. A motor having a shaft supporting and driving a. fan positioned Within the fan chamber is positioned within the fan and motor cas ing, and. provides a transversely extendingsurface facing the. transversely extending surface on theradially inwardly directed annular wall portion when the motor is disposed within the fan and motor casing in a" position to support and drive a fan within the fan chamber, and the motor is I so constructed that there is clearance between (around):

it. and. the. most adjacent surrounding parts of the fan andmotor casing when it is so positioned." To secure the' motor in fixed relation to the fan and motor casing and maintain a. coaxial relation between the motor shaft and v thebounding wall of the fan chamber, there isfprovided means for. effecting-forcible diminution of" the distance bet'weenfthe, transversely extending surfaces, -and also means which. through embed-merit in the materialbacking one of said surfaces, at least, and in non-sliding relation to the other of said surfaces fixes the motor with its shaft, and the fan on said shaft coaxial. with the fan chamber and provides for uniform minimum blade tip' clearance; Said'tneans for fixing such relative radial position includ ing partially embeddable means may take the form of ele-- ments integral with, pressed up from or formedupon-the. exteriorof one of said surfaces, or separately formed and eithertixed in or to one of said. surfaces, or even merely positioned between the same, harder than the material. of the surface or surfaces into which it is to be forced and Pa ially embedded, such elements being, say, of steel when the surface, orsurfaces, to be penetrated are aluminum, for example, or metal when such surface, or surfaces, are a plastic, and the pattern of arrangement of said elements and of the means for movihg saidv surfaces together being;

holding forces, and desirably to facilitate proper reassembly in the event that dismantling be for any reason required.

From the method aspect, in a preferred practice thereof my invention may include the steps of fixing a fan and motor casing to a jig which has means for positioning a motor shaft coaxial with a fan chamber surface on the easing, placing'a motor with its shaft in such positioning means, forcibly moving longitudinally the motor casing relative to the fan and motor casing by means permitting radial freedom between said casings, and, through means forced into an interlocking relation to one orthe other or both of said devices by such relative longitudinal movement, preventing relative lateral movement between said casmgs.

I Referring now to the drawings, and first to Fig. 1, it will be observed that a fan and motor casing comprises an outer annular portion or wall 11 connected to an inner annular portion or wall 12 by a series of radially extending vanes 13, 'these vanes being appropriately spaced about the axis of the casing and shaped to produce the desired effect upon the flow of the air displaced by the fan later described. The inner wall 12 surrounds a chamber 14 in which a fan driving motor 15 is adapted to be received, and the Wall 12 has connected intergrally with a radially (transversely) extending wall portion 16 traversed by openings 17 throughwhich studs may extend and having also a central opening 18 through which a nose portion 19 of reduced diameter formed upon the motor 15 may extend. It will be noted that the wall portion 16 is a portion of a structure which rigidly and integrally connects with the inner ends of the vanes 13. Desirably, but not necessarily, the surface 20 of the wall 16 nearer the chamber 14 may be made plane and disposed at right angles to the axis of an internal surface of revolution 21 which bounds a fan chamber 22 in the fan and motor housing 10. Ordinarily, the surface 21 will be an internal cylindrical surface but it may be an internal frusto-conical surface, for example, or-assume other forms if desired. For the purposes of the present invention it is important, howeverthough not vital with a diiferently constructed jigthat this surface shall be adapted readily to receive and closely to fit upon a corresponding external surface formed upon a jig.

Figs. 1 and 2 also show a jig 25 having openings 26 through the same so that the socket end of a torque wrench, orrthe like, may be inserted through them. This jig has a pair of coaxial surfaces of revolution, an internal surface of revolution 27 formed closely to fit the shaft 29 of a motor which is to be positioned and mounted in the fan and motor casing, and an externalsurface of revolution 28 adapted closely to fit the internal surface of revolution 21. When the fan and motor casing 10 is positioned with its surface 21 snugly fitting upon the surface 28, the surface 27 will be coaxial with the surface 21, and accordingly a motor shaft closely fitting the surface 27 will be coaxial with the surface 21, with the result that a fan, the tips of whose blades lie in a surface of revolutron coaxial with a shaft-receiving socket in the fan hub will, if the socket is a close fit for the motor shaft, be coaxial with and able to have a very small but safe clearance within the surface 21, provided the motor casing is fixed, after positioning in such relation to the fan and motor housing, that its shaft will remain coaxial with thesurface 21.

To accomplish maintained centering of the shaft 29 of the fan driving motor with the surface 21 of the fan chamber, there is provided means hereinabove described by which, through coaction of means carn'ed by an end wall of the motor casing with the surface 20, the desired coaxiality may be permanently established.

It will be evident that instead of providing the surface 20 on thewall 16 and providing on the end wall 30 of the motor casing, the parts could be reversed. It will also be clear that while there are shown conical projections 31 in a generally rectangular disposition as shown in Fig. 4 upon the end wall of the motor casing, other figures adapted to prevent lateral slippage between the motor casing and the fan and motor casing and other dispositions-on either wall or merely between the walls-might be employed.

For the purpose of drawing the projections 31 into a condition of interengagement with the wall 16, there is illustrated traction means in the form of a pair of studs 33 carried by the motor casing and extending in the assembled relation of the parts through the openings 17, the openings 17 being of sufiiciently greater diameter than the studs 33 to permit centering of the motor casing without side cramping of the studs. Lock washers 35 and nuts 36 are provided to cooperate with the studs 33, but it will be evident that these are merely illustrative, for other suitable means for producing appropriate tension in the studs 33 and maintaining such tension may be em-; ployed. The projections 31 are illustrated as in pairs at.

opposite sides of adiametric plane in which the axes of the studs lie, and but two studs are shown, but it will be clear that this is but illustrative of various arrange. ments of studs and projections which will serve the purpose. The projections may assume various forms and may be integral with the motor head when the latter is of harder material than the wall 16, or be in the form of inserts, and are not limited to conical form. Desirably the casing 10 may be a monobloc casting or molding, of aluminum or plastic and the projections 31 of steel or other hard metal.

The mode of operation of assembling a fan will now be readily followed from what has been said. The jig 25, which may be supported either horizontally or vertically, may have a fan and motor casing 10 mounted upon it with the surface 21 closely surrounding the surface 28. This will result in a coaxial relationship between the surface 27 and the surface 21. At the time of assembly of the fan and motor casing upon the jig, a motor 15, with its studs 33 projecting through the openings 17 and with lock washers 35 and nuts 36 loosely holding the motor in the casing, may be disposed within the chamber 14, or the motor may be placed in the chamber 14 after the casing 10 is centered upon the jig. The

motor shaft 29 will in any event be received in the boresurrounded by the surface 27 as the parts are assembled and so the motor body may be brought into such relation to the fan and motor casing that the shaft 29 will be coaxial with the internal surface of revolution 21. Of course, if it be preferred to insert the motor in the fan and motor chamber 14 after the fan and motor casing has been located upon the jig as indicated in Figs. 1

and 2, this is entirely feasible, and the nuts 36 and lock washers 35 may be placed in the socket of a wrench inserted through the jig-openings 26 and thus positioned on the ends of the studs without difiiculty. In any event, with the motor 15 having its casing received with clearance within the chamber 14, but with its shaft held coaxial with the surface 21 bounding the fan chamber, it will be possible, by tightening up the nuts 36 relatively uniformly, as by means of a torque Wrench, to effect an interengagement of the points of the projections 31-a partial embedding of their ends so as to form a'permanent seat for them-in the radial wall 16, and such tension. may be applied to the studs 33 as to insure against the possibility of loss of coaxial relationship between the motor power shaft and the surface 21 of the fan chamber. After the parts are assembled, the nose 19 and the adjacent portion of the wall 16 may be marked or scribed so' that, in the event that it is necessary to remove the motor from the fan and motor casing, correct relationship of the parts may be restored readily, and then merely by relatively uniformly tightening up the nuts again,; a

coaxial relationship of the parts may be again secured.

'5 0f cour'seif a special non-uniform pattern ofthe projections, or of the projections and the studsbe used, scrib ing. or the like will be. unnecessary to effect restoration of the parts to the desired coaxial relation of the shaft 29 with the surface 21.

After the motor has been fixed withits-shaft in coaxialv relation tothe surface 21, the fan and motor casing and motor assembly can be removed from the jig and a fan element 49 can be applied to the projecting motor shaft 29 and held in position in any desired manner asby' a keyand a nut and washer or a cotter pin, or the like.

It will bev evident from the foregoing that. there is. provided not only an improved fan. structure but. a very economical structure to build, one which will assureclose: blade tip clearance, andhighv aerodynamic efliciency, and also that there is provided an improved method of. assemblingmassproductionimotors. in mass production fan and motor. casings, calculated to permit rapid andv inexpensive production butto provide. a product having high; aerodynamic efficiency.

This application is a continuation of application Serial- No. 783,147, filed October 30, 1947,. now forfeited:

While. there is. in this application specifically described one form both as to apparatus and as: to method which:

the. invention may assume in practice, itwill beunderstood that these forms are shown for purposes of illustration and that the invention may be modified and embodied or practiced in various other forms without departing from its spirit or the scope-ofthe appended claims.

Whatis claimed is:

1. In combination, in an axial. flow fan, a' fan and motor casingcomprising an outer annular wall and an inner annular wallin substantially concentric relation and aplurality of circumferentially' spaced vanes connecting said walls and maintaining them in'spaced' relation, said outer annular wall circumferentially bounding a fan chamber'and said inner annular wall bounding a chamber into which a motor is adapted to extend, said inner annular wall having a radially inwardly directed flange providing a transversely extending surface and surrounding an opening. of substantial diameter, a motor having a casing between which and said inner wall clearance exists when said motor is assembled with said fan and motor casing, said motor having a portion extending into said opening and having a shaft, a fan for which said shaft constitutes a support and driving means, said motor casing having a wall having a surface thereon facing said. transversely extending surface when said motor casing is. arranged inside said inner annular wall and its shaft is supporting said fan inside said fan chamber, and; means for fixing said motor casing relative to said fan and mo. tor casing to center said fan in said fan chamber including only means adjustable to diminish the distance between said surface and means between said surfaceslandsubstantially spaced from saidopening, andv pressed into at least one of said surfaces and forming a seat for itself therein as the distance .betweensaidsurfaces is decreased below a predetermined amount.

2. The combinationdefi'ned inclaim I in which said means between said. surfaces. and substantially spaced from said opening. and pressed into at least one of said surfaces is carried by said wall of said motor casing and is pressed into said transversely extending surface on said radially inwardly directed flange.

3 The combinat'mn defined in claim 1, in which said mean between. said surfaces and substantially spaced from said opening. andpressed intoat least one of said surfaces projects from one of the latter and extends into material backing the other.

4. In combination, in an axial flow fan, a fan and motor casing comprising an outer annular wall and an inner annular wall in substantially concentric relation and a plurality of circumferentia-lly spaced vanes connecting said walls and maintaining them in spaced relation, said outer. annular wallextending, beyond one. end. ofsaid? inner annular wall. and circumferentially bounding a fan; chamber and. said. inner annular wall having: a radially inwardly directedflangeprovidingatransversely extending. annular surface surrounding an opening of substantial diametena. motor. having a casing and a shaft, said motor casing received with peripheral clearance within said. inner annular wall andhaving a portion extending. into. said opening,. a fan for which said shaft constitutes. a. support and driving means, said motor casing having a; surface thereon facing said transversely extending surface. when said. motor casing is. arranged inside said. inner annular wall audits shaft is supporting. said fan inside said. fan: chamber, and means for fixingv saidmotor casing.

' relative to. said fan. and motor. casing to center said. fan

in said fan. chamber including means adjustable to diminish. the distance. between said. surfaces and means. producing under the. action of said adjustable. means. permanent dents. in. positions substantially spaced. from. said opening int atleast one of. said. surfacesand seating. in. said dents. to prevent relative. transverse movements. between said surfaces;

5. In combination, in an axial flow fan, a fan. and motorcasing comprising. an outer annular walland an. inner annular. wall in substantially concentric. relation. andv a plurality of. circumferentially spaced vanes c0n:-- nesting; saidwalls. and maintaining them in spaced relation,. said. outer annular wall extending beyond one. end.. ofsaidinner annular wall and circumferentiallybounding a.fan chamber.- andsaid. inner annular wall having a radi.-- ally inwardly directed flange providing a transversely ex-. tending; surface, a motor having a casing and a shaft, said. motor. casing received. with peripheral clearancev within said inner annular. wall, a fan for which saidshaft.

;constitutes. a support and driving means, said. motor casing having a surface thereon facing said. transversely extending surface when. said motor casing is arranged. inside. said. inner annular wall and its shaft is supporting: said fan. inside said fan chamber, and. means for fixingv said motor casing relative to said fan and motor casing, to center said fan in said fan chamber including means adjustable to diminish the distance between said surfaces. and. aplurality of projections having sharp extremities in spaced. relation to each other carried by one of. said.

surfaces and pressed into the other of said surfaces so' as:

to: form seats for themselves therein as the distance her-- tween said. surfaces is decreased. below a predetermined. amount.

6. In combination, in an axial flow fan, a fan and.

-. motor casing comprising an outer annular wall and an inner annular wall in substantially concentric relation. and a plurality of circumferentially spaced vanes connecting said. walls and maintaining them in spaced. relation, said outer annular wall circumferentially bounding; a fan. chamber and said inner annular wall having a transversely directed portion in the form of a radially inwardly directedv flange providin an annular surface facing lengthwise of said casing and surrounding an; annular opening of substantial diameter, a fan in said fan. chamber, a motor having a casing and a shaft supporting said fan, said motor casing received with peripheral; clear.- ance. within said inner annular wall and having a surface. facingsaid first mentioned surface and having a portion. extending into said opening and surrounded by said second mentioned surface, and means for supporting said motor with the axis of said shaft. in the same straight line with the axis of said fan chamber including tension elements' extending between said motor casing and said flange and position fixing means between said surfaces and having sharp portions embedded in at least one of the latter in laterally offset spaced relation with respect to said opening.

7. In combination, in an axial flow fan, a fan and motor casing comprising an outer annular wall having a portion circumferentially bounding a fan chamber and having another portion beyond which said fan chamber is disposed, a plurality of circumferentially spaced vanes extending inwardly from said another portion of said outer annular wall and means connecting the radially inner ends of said vanes providing, for the support of a motor, a radially inwardly directed annular wall portion presenting a transversely extending surface, a motor within said fan and motor casing having a casing and a shaft and supported by said fan and motor casing wholly by said radially inwardly directed annular wall portion and about which motor casing and between the latter and the most closely adjacent portion of said fan and motor casing clearance exists when said motor is assembled within said fan and motor casing, a fan for which said motor shaft constitutes a supporting and driving means, said motor casing having a surface thereon facing said transversely extending surface when said motor casing is arranged inside said fan and motor casing with its shaft supporting said fan inside said fan chamber, and means for fixing said motor casing relative to said fan and motor casing and centering said fan in said fan chamber including only means adjustable to diminish the distance between said surfaces and means producing under the action of said adjustable means permanent dents in at least one of said surfaces and seating in said dents to prevent relative transverse movements between said surfaces, said permanent dent-producing means comprising a plurality of projections having sharp extremities in spaced relation to each other carried by one of said surfaces and pressed into the other of said surfaces as the distance between said surfaces is decreased below a predetermined amount.

8. In combination, in an axial flow fan, a fan and motor casing comprising an outer annular wall circumferentially bounding a fan chamber, a plurality of circumferentially spaced vanes extending inwardly from said outer annular wall and means connecting the radially inner ends of said vanes providing, for the support of a motor, a radially inwardly directed annular Wall portion presenting a transversely extending surface surrounding an opening of substantial diameter, a motor within said fan and motor casing having a casing and a shaft and supported by said fan and motor casing wholly by said radially inwardly directed annular wall portion and about whose casing clearance exists when said motor is assembled within said fan and motor casing, said motor comprising a part thereof surrounded by said opening, a fan for which said motor shaft constitutes a supporting and driving means, said motor casing having a surface thereon facing said transversely extending surface when said motor casing is arranged inside said fan and motor casing with its shaft supporting said fan inside said fan chamber, and means for fixing said motor casing relative to said fan and motor casing and centering said fan in said fan chamber including only means adjustable to diminish the distance between said surfaces and means producing under the action of said distance diminishing means permanentseats in radially outwardly spaced relation to said opening in at least one of said surfaces and seating in said seats to prevent relative transverse movements between said surfaces.

9. The method of assembling and securing, with true coaxial relation between fan chamber and motor shaft, in a fan and motor casing which has (1) a fan chamber and (2) wall portions, including (i) an annular wall and (ii) a radially inwardly directed flange at one end of said annular wall, said wall and flange forming a motorreceiving chamber and said flange having openings through it for the reception 'of threaded motor-holding elements and also surrounding a further opening for a portion of a motor to enter, a fan drivingmotor which has '(a) a casing rotatably supporting a fan driving'shaft and receivable in'said motor-receiving chamber withperipheral clearance, and (b) a portion receivable in the opening'surrounded by said fiange which method includes (I) positioning a jig, which has a central bore of a size closely to-receive the motor shaft, in interfitting relation with the fan chamber and thereby locating such central bore coaxial with the fan chamber, (II) positioning the motor with its shaft in such bore and its casing in the motor-receiving chamber in spaced relation to such annular wall and (III) establishing, by relative longitudinal movement between said motor casing and said fan and motor casing effected through the exertion of traction between said flange'and 'said motor casing by holding elements extending .with. lateral clearance through the openings in said flange, an interembedding relationship between pointed elements lying between mutually adjacent opposite surfaces on the end wall of said motor casing and on said flange and that one of such'surfaces towards whichsaid pointed elements are directed, to effect a rigid securing of said motor in said fan and motor casing mainly by the coaction of said pointed elements and the seats they form for themeselves, and (IV) thereafter separating said fan and motor casing and said jig from each other.

10. T he method of assembling and securing, with true coaxial relation between fan chamber and motor shaft, in a fan and motor casing which (1) provides a fan chamber and (2) has Wall portions includingjvanes and a radially inwardly directed flange in fixed relation to said vanes, said flange having openings through it for the reception of threaded motor-holding elements and also surrounding a further opening for a portion of a motor to enter, a fan driving motor which has (a) a casing rotatably supporting a fan driving shaft and (b) a portion receivable with clearance in the opening surrounded by said flange, which method includes (I) positioning a jig, which has a central bore of a size closely to receive the motor shaft and a coaxial surface to interfit with the fan chamber, in interfitting relation with the fan chamber, and with said central bore receiving the motor shaft while the motor casing is in spaced relation to such annular wall, and (II) establishing, by relative longitudinal movement between said motor casing and said fan and motor casing effected through the exertion of traction between said flange and said motor casing by holding elements extending with lateral clearance through the openings in said flange, an inter-embedding relationship between pointed elements lying between mutually adjacent opposite surfaces on the end wall of said motor casing and on said flange and at least one of such surfaces to effect a rigid securing of said motor in said fan and motor casing mainly by the coaction of said pointed elements and the seats they form for themeselves, and (III) thereafter separating said fanv and motor casing and said jig.

References Cited in the file of this patent UNITED STATES PATENTS