US2251887A - Flexible fan unit - Google Patents

Description

Aug. 5, 1941.

' a P. LARsH FLEXIBLE FAN UNIT s suena-smet 1 Filed Jima 13, 1938 A086 5- l941- E. P. LARsH 2,251,887

umana ma uuu l y Filed June' 1 s, 193s s sheets-shut l2 Aug. 5, 1941. E. P. LARsH FLEXIBLE FAN UNIT Filed June 13, 1938 3 Sheets-Shogi. 5

Patented Aug. 5, 1941 UNITED sTA'ras-p PATEN'iA OFFICE Everett r. AhTslnor to The Master Electric Company,

poration of Ohio Dayton, Ohio, a cor- Applicatlon June 13, 1938, SerialNo. 213,359 18 Claims. (Cl. 17o-'159) This invention pertains to electric fans. and more particularly to reinforced blades therefor of flexible or pliable material and the method of manufacture thereof.

Use of non-rigid flexible or resilient fan blades to minimize injury upon contact therewith and to obviate the 4necessity for enclosure guards has been long known. In some. instances these fan elements have been pliable or exible straps, connected at their ends, and in others the blades are normally limp wings which are distended by centrifugal influence during rotation. In stillother embodiments the material of the blades has been impregnated with some stiffening material or the blades have been molded from rubber'or other composition in such a way as to render them somewhat'self-supporting or resistant. However, these devices have for the most part lacked 4stability and have been ineillcient in use, tending to yield to air resistance and are otherwise objectionable.

The present fan vblade structure forming the subject matter hereof is reinforced by a formed metal insert or abbreviated blade of somewhat smaller size, suitably shaped and contoured, which is embedded in the flexible materialof the blade to afford suilicient rigidity throughout the major portion thereof to enable it to retain its prescribed. shape and inclination or pitch against air resistance, and beyond which the margins and terminal extensions of the blade aresuiliciently flexible and resilient that they yield to contactv with an interposed obstruction at operating speed.andaresuillcientlyresilienttobeself restoring when so distorted from normal shape.

The object ofthe invention is to improve the Aconstruction as well as the mode of operation of A further object of the invention is to minimize noise during operation.

A further object of the invention is to assure retention of a prescribed vshape and pitch of the blade, minimize the necessary amount of rubber or other flexible material, and reduce the weight of the completed impeller unit.

A further object of the invention is to provide an improved method of mounting the impeller.

A further object of the invention yis to provide a rotary fan having the herein mentioned advantageous structural features and meritorious characterlstics.

With the above primary and other incidental objects in view as will more fully appear in the specification, the invention intended to be protected by Letters Patent consists of the features of construction, the parts and combinations'thereof, and the mode of operation, or their equivae lents. as hereinafter described or illustrated in the accompanying drawings. i

I'n the drawings, wherein is shown thev preierred but obviously not necessarily the only form of embodiment of the invention, Fig. 1 is e side elevation of an electric fan equipped with a rotary flexible rotorjor blade unit embodying the present invention.

Fig. 2 is a front elevation composite rotor or impeller.

Fig. 3 is a side elevation thereof.

Fig. 4 is a transverse sectional view through one of the blades.

Fig. 5 is a front elevation of the petaliform reinforcement insert or core member.

repair.

A further object of .the invention is to provide a v fan blade having sufhcient nexibility to prevent injury in event of accidental contact, wherein the deformation is restricted to a limited area without destroying' or materially decreasing the air impelling action ofthe blade while'so deformed ortemporarilydisturbingitsbalancetoanyappreciable degree. A l

Amrth'erobjectoftheinventionistoincrease the stability of iiexible fan blades and provide a maximum effective air impelling area under all conditions.

Fig.'6 is a side elevation of the reinforcement core before embedment in the resilient blade ma- Fig. 'I is a radial section through the blades and hub of the impeller.

Fig. 8 is a front view of one member of a sectional reinforcement core.

Fig. 9 illustrates an economical mode of blankingthesectionsshowninllg.8.

Fig. l0 is a front elevation ofan assembled sectional core. y

Fig. ll is a sectional view of a'modication..

Fig. 12'is a detail view of a single blade element.

of reference throughout the several views.

In the drawings, l indicates'. eonvenuonsl pedestal and motor housing'ofaportable elecof the assembled v Pitch angle at all times.

tric ian, the particular shape and detail construction of which are not material to the present invention. Mounted on the motor shaft is the ameter oi the motor shaft on which the impeller composite impeller or blade unit 2 forming the subject matter hereof. For illustrative purposes the impeller is shown as comprisingv a group of four radially disposed, internally reinforced blades 3.-3. The number of blades and the particular shape thereof may be varied to accommodate the fan to different operating conditions and requirements. The major bodies of the blades 3 may be formed of any suitable pliable or resilient material such as paper, fabric,flber, or the like, but are preferably molded from soft or semi-soft rubber. While the several blades 3 may be independently formed and subsequently assembled into the'unitary impeller 2, the blade'assembly is preferably formed as a single integral unit.v

Embedded in the impeller is ametallic reinforcement core t or insert shown in Figs. `5 and 6, stamped or otherwise formed from sheet metal. The core. orinsert licomprises a plurality of integrally interconnected radially ldisposed leaves of obovate form, which may .be well termed a petaliform insert or core. The fan blades 4,' including the Ileaves or petals of such petaliform insert,'emb`edded therein are transversely curved or of ooncavo-convex form. In addition to such curvature they are inclined to the common plane of rotation, thus aEording a pitch angle com-I mensurate with the desiredair impelling action.

or ian. bladeunit is to be mounted. A4 group oi' additional holes 8 are also provided in diie'rent radial positions about the central shaft hole 1,

the size o, which is also reduced'in like manner holes 'i and 8 provides a flexible; somewhat resilient mounting for the rotor unit which absorbs vibration and minimizes noise. It further enables therrotor -to automatically adjust itself f within reasonable limits into the plane of rota-.-

Y tion if it should become inclined thereto.

Adjacent to the inner ends of the bladesat which they are joined to each other, the leaves or petals of the petaliforminsert are interconnected by a disc like hub portion. The contigf nous portions yof the reinforcement leaves are embossed to afford stiiening beads or ribs 5.

For illustrative purpose the stiilening beads or ribs have been shown as of arcuate form grouped in spaced relation about the center of the core or insert. They may, however, be otherwise disposed in such relation as will best meet the requirements and conditions of use to which the impeller is to be subjected. Such construction andconiiguration renders the blades ot the im` peller suiilciently rigid to maintain its effective The embossed ribs or beads Salso serve to materially strengthen the impeller blades at their otherwise weakest points, i. e., their juncture with the hub, to prevent breakage or bending of of the insert.

The rubber or other flexible covering` of the insert may be applied in any suitable manner or customary way. Ordinarily this is performed in a' suitable mold under heat. and pressure. It is, however, 'highly important that each of the fan blades shall contain equal amounts of material and that the petaliforminsert or vcore shall be symmetrically located. toafford a properly balnelly-and transversely. are greater than thosev The tips of the bladesextend al considerable distance beyond the termini of the insert leaves as shown by solid and dotted lines in Fig. 2. Likewise the leading and'trailing edges of the blades extend beyond the edges of the reinforcement insert. Such extended portions are sufficiently flexible to yield 'under impact and permit the lextensions of the blades to bend withoutbreakage or permanent distortion. Such portions are suiliciently resilient and possess with a series of transverse ribsv 9 of low altitude. as compared with their width. The ribs or beads 9 are of curvilinear form concentric withk the the blades out of their common plane or rotation. I

-To aiord increased anchorage of the rubber or other iiexible or pliable material of which the blade is formed and in which the petaliform core or insert is embedded, the latter is'provided with a series oi holes 6 6, through which the mateerial at opposite sides ofthe insert is integrally united. These are shown as transverse sl'ots,. but

may be otherwise shaped,and may comprise a series of spaced round or irregular holes or elonp gated slots otherwise disposed in each leaf or petal of the unitary insert.' I

At its center the insert is provided with a hole 1, preferably, lalthough not necessarily, largerl than the diameter of the shaft on which the impeller is to be mounted.

During the subsequent embedding operation.v

in which a body of flexible or resilient material is molded or otherwise formed about. the insert,

Athe rubber or other enclosing material partially illls such hole 1, uniting through the hole the enclosing material at opposite side of the insert for increased security and thereby reducing the size of the hole to somewhat less than the diaxis of the rotor or impeller.

"coincident with the center of the unitthere` is formed a projecting conoidal hub l0 having` therein an axial bore and a series of relatively spaced bores parallel thereto coincident with the holes l and d of the insert. The hub l0 is'integother exible body while. dat and the blades subsequently shaped tothe proper curvature and pitch inclination. However, the preferable method is to contour the insert leaves to their nnal shape before embedment and thereafter mold the rubber or like material thereabout into f agreement with the bladesor leaves of the preformed insert.

By such construction strains and stresses in the rubber cover as well las in the insert are' avoided and the material may be more uniformly,

distributed.y The extensions vof the' rubber blades beyond the limits of the insert, as indicated in Fig. 2, provides flexible terminals and also exible leading and trailing edges which extend cn-YV siderable distances beyond the perlpheries of petal or leaf sections of. the insert and which will yield upon impact engagement with an object without injury to either the blade o! the object and -will resume their original shapes when free therefrom. The provision of the reinforcement insertandtheofthecentralportion thereof affords such construction and configuration as to maintain the pitch angle'and concavoconvex contour of the fan blades under all conditions. integral'component of the final impeller structure and an inherent part of each blade thereof,

The reinforcement insert becomes anf like, such yielding effect of one reinforced blade rendering the blades self-supporting and amply rigid throughout the inner radial portions thereof to perform their air impelling functions while' core member in the mold in symmetrical relation therewith while the rubber is being molded there# about. The rubber mold is -provided interiorly with a group of studs corresponding to the studs I3 which in the finished product afford the spaced bores 8', and over which the reinforcement core is positioned with such locating studs engaging -in tne holes 8 thereof. Such locating use is adaditional to the driving function of the-holes. In the event that the impeller is' of smallsize or not subject to great load, it may be frictionally engaged upon the drive shaft l2 by merely press- Y ing tne shaft into the central bore 1 without use of driving studs I8 to engage the bores 8. I'he bore l being of somewhat smaller diameter than that of the shaft, the contiguous rubber material is subjected to expansive tension causing the shaft to vbe firmly gripped by the rubber hub.

While the reinforcement core is illustrated and described as comprising multiple integrally interconnected leaves, it maybe assembled from separately formed elements consisting initially of either single or double leaf elements united by welding or riveting or otherwise, or such independent reinforcement elements or inserts may be separately embeddedin the enclosing body of rubber and flexibly inter-connected by the con-l tiguous portions of rubber. v

The single integral reinforcement insert I having'integral radially disposed leaves cannot be blanked from the sheet material without con#-4 siderable waste. However, if the reinforcement insert leaves are formed in pairs as Vsliown'in Fig. 8, they may be more y'blanked ilwithminimumwasteof would not be subject to the fullflmonientum or inertia of the impeller. Such commotion would possess a'slight shock absorbent characteristic under such circumstances. By supporting two of the separately formed units in the rubber mold in slightly spaced relation with each other and embedding them in a single body of rubber or the relativey to another may be achieved. In Fig. 11 such relation of separate reinforcement or insert elements flexibly connected is illustrated. If so desired, each reinforcement leaf may be separately formed and indeed separately embedded in v rubber for assembly side by side on a drive shaft.

In Fig. 12 there is shown one such single reinforced flexible blade element, and in Fig. 13 a f series of such individual flexible reinforced blades .are shown assembled in cooperative relation on a drive shaft. Such assembly may consist of two,

three or any greater number of blade elements. Such members agree generally in form and construction with those previously described, -including a simlar insert leaf l and integral hub portion embedded m a flexible rubber feit or com. i

position blade of greater size, including a rubber hub portion.

From the above description it will he apparent that there is thus provided a device of the character described possessing the particular features of advantage before enumerated as desirable, but which obviously is.v susceptible of modification in its form, proportions, detail construction and ar-` rangement of parts without departing from the principle involved or sacrificing any of its advantages.

While in order to comply with the statute the invention has been described in language more or less specific as to structural features, it is to -be understood that the invention is not limited to the specic features shown, but that the means and construction herein disclosed comprise the preferred form of severall modes of putting the invention intoreiect, and the invention is therefore claimed in any of its forms or modiiications within the legitimate and valid scope of the appended claims.

Having thus described my invention,I claim:

1. A fan element including' a hub portion and ,a plurality of integrally united blades molded to shape from rubber, a unitary metallic petaliform core member of sheet metal reinforcing the hub and inner radial end only of each blade.' 'the outer radial portion of each blade being free from any reinforcement and being sufficiently soft and inFig.lilandunitedbyxveldingorbyrlveting.k

In lieu thereof itis quitepractical and desirtvetoeachother. 'lhisis for use under conditi@ where fingen may be intothepathofrot'atlonoftheblades. Uponcontactwithanintereeptingnngerorother flexible to yield upon engagement with an object and having capacity toresumeits shape when free from the object..

2. A fan element presenting a petaliform core portion of sheet metal and rubber covering the core member'andextendlng radially ly beyondtheperipheryofeachofthepetalsections of the core member, thereby' providing a' rubber fan in which each blade is interior-ly reinforced at its inner radial end and the outer radial portion ofwhlch is soft and flexible.

3.a fan element having a petallformucore portion of sheet material and rubber enclosing eachpetaisectionofthecoreportinntoform the'blades ofthe fan and'also enclosing the central part of the core said yrubber having considerable thickness unid-centrar partofthecorethaebytoformarubberhub foryliae fan, the rumerportion ofAeach blade radially considerablyv beyond the peextending mmebladewnd'slightlyyieldand is ripheryofitspetalsectlonof the core to provide `ber portion of each blade'extending radially considerably beyond fthe periphery of its petal sec tion of .the core to provide an outer radial por--k tion for the blade which is sumciently exible to yieldwhen it engages an object but which is capable of resuming its normal shape when free from said object, said rubber hub portion of the fan element having an axial shaft-receiving Opening.

5. A fan element comprising' a hub and blades formed of rubber and a petaliform core member of sheet material embedded in and entirely enclosed by the rubber with av petal section of said core located at andreinforcing the inner radial end only of each blade, the outer radial portion of each blade being'freev from reinforcement and being self-sustaining but sumciently flexible to yield when engaged by an object and capable of i resuming its normal shape when free fromsaid object.

6. A fan element presenting a petallforrn core portion of sheet metal, the petal sections of which have va. pitch angle corresponding to the pitch angle required in each blade of the fan and an integral rubber portion which covers the core portion and forms both a rubber hub for the ian and the blades thereof, the rubber part of each blade extending radially considerably beyond the periphery. of the petal section .thereot and normally having a less pitch angle than that of the corresponding petal section, the rubber portion of each blade being held in distorted condition at said required pitch angle of the blade bythe corresponding petal section of the core, the outer radial portion of each blade beingvsumciently flexible to yield when it engages an object but being capable of resuming its normal Shape when iree from said object.

7. A fan comprising a hub, radially projecting` blades carried thereby, and a petaliform reinforcement insert embedded interiorly thereof. said blades being formed at their outer portions of material snmciently exible to ,bend readily without permanentjdistortion, and the inner end -thrusts Without materially increasing their re= 'sistance to deformation upon encountering an Aao object in' their path of rotation.

10. In a fan, a hub, a plurality ber blades, and a petalifonn reinforcement means embedded'interiorly thereof and coacting with said hub and base portions of said blades to maintain said blades in a'self-sustained radial position on said 'hub oblique to the axis of rotation, said blades being sufiiciently iiexible and resilient to be-self-restoring after striking an object in its path of rotation and oi sufilcient rigidity to substantially maintain a pitch angle upon rotation effective for air delivery.

11. In a fan, a hub, rubber blades, and a petaliform reinforcement member embedded within and engaging portions of said blades for maintaining them in a normally radial and substantially cupped position on said hub, said blades being of such flexibility and resilience as to be self-restoring upon distortion from normal position and of suilicient rigidity when assembled to substantially maintain a predetermined pitch position on the hub.

[12. A fan comprising a hub, radially project-4 ing blades carried thereby, said blades being formed of material suciently flexible tobend readily Without permanent distortion, and a .petaliform reinforcing member embedded in the inner end portions of said blades of a construction and configuration such that said blades are sufficiently rigid to substantially maintain their pitch angle upon rotation, and said blades being relatively wide with respect to their radial dimension. A l

13. A fan comprising a hub, radially projecting blades carried thereby, said blades being formed of a. material sufficiently iiexible. to bend readily vupon striking an object without permanent dis-v tortion, and 'a petaliform reinforcing element embedded in the inner end portions of said blades,

' of a construction and configuration such that Portions of said blades being' of a construction andconguration such that said blades are sumciently rigid to maintain a substantially radial position at all times.`

8. A fan comprising a hub, radially projecting blades carried thereby, and a petaliform reinforcement insert embedded interiorly thereof, said blades being formed at their outer portions of material suillciently flexible to bend readily withoutl permanent distortion, and the inner end portions of said blades being of an obliquely curved configuration and a construction such that said blades are 'suciently rigid to maintain an eifective pitch angle upon rotation.

9. A fan comprising a hub, radiallyproiecting blades formed of material sufficiently flexible to bendreadily without permanent distortionpand a petaliform reinforcement of less extent than the V`blades embedded interiorly thereof, the inner end portions of said blades being maintained sunlciently rigid by said hub and of a configuration to increase the resistance of said blades to axial said blades are suiciently rigid to maintain an effective pitch angle at all times.

14. A rotary fan impeller including a plurality of radially disposed'blades of flexible material and a centrally disposed conoidal hub thereforof like material formed integrally with the flexible material of the blades, and a unitary reinforcement insert comprising multiple interconnected radially disposed leaves of strain resistant material, one leaf of which is ,embedded in each blade thereof of the impeller and a central portion of the insert integrally connecting the leaves one with another and embedded `in the conoidal hub of the. impeller, said hub and insert havingtions fixedly interconnected with each other and I a rubber covering in which the reinforcement core assembly 'is embedded, said covering extending beyond the periphery of each vsection of the core, thereby providing a fan elementin which each blade is interiorly reinforced at its inner radial end and the oiiter radial portion of which is soft and flexible. A

16.v A fan element including a petaliform reinforcement core comprising plural separate sections' andA a rubber covering in which the reiny forcement-core sections are. embedded and by which they are yieldingly connected with each other, said covering extending beyond the periphery .of each section of the core lthereby probl, and a hub portibn upon each blade by whichviding a Ian element in which i,he` bladesare. in-y teriorly reinforced at their inner radial ends and the outer portions of which are soft and flexible, the blades being yielding in relation one to another in the plane of rotation.

17. A fan element including -plural separate reinforcement core sections disposed in petaliform relation, a rubber covering in which each core section is embedded, said. covering extending beyond the periphery of the enclosed reinforcement core section thereby providing a plurality of separate fan blades each of which is interiorly reinforced at its inner radial end and the outer radial portion of which is soft'and ilexithe blades may be assembled in radiating relation side by side on a common shaft.

13.y As an article of. manufacture, a reinforcementinsert for al rubber fan element, comprising a single integral petaliform member formed from sheet material including a plurality of radially disposed leaves and a central interconnecting hub portion and a, plurality of spaced locating holes in said member for engagement of locating studs for positioning the'insert in a niold to. receive a body of embedding material ande embossed areas on the member to stiien such portions thereof. EVEREI'I' P. LARSH.

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