US1781165A - Centrifugal fan - Google Patents

Description

Nov. 11, 1930. A. A. CRIQUI CENTRIFUGAL FAN Filed Oct. 18, 1928 Illlll Patented Nov. 11, 1930 ALBERT A. career, foi flnurrano, NEW YonKj-nssre-noa'ro BUFFALO roaeacoivn PANY, on narrate, NEVJ YoaK, A oonroaarron on new Year; I

' QENTRIFUGAL FAN;

Application filed October 18, 1928. Serial No. 313,21 1.

My inve-ntion relates in general to multiblade, centrifugal fans of the type inwhich a large number of blades are arranged in annular form around a central space open at one side for the entrance of air which is drawn in through the central opening and forced outwardly through the spaces between the blades by centrifugal force.

It is well known to those skilled in the art to that in fans of this type, it has been the inventors object to produce fans in which the velocity of the air leaving the wheel would be greater than the peripheral velocity of the wheel. Since air currents produced by this type of fan are usually delivered under a comparatively slow speed of rotation, it is necessary that large motors be employed in order to maintain the slow speed where the motor and fan are direct-connected. r i

The principal object of my invention has been to provide a fan in which the velocity of the air leaving the blades shall be less than the velocity of the periphery of the fan wheel,

thus enabling the fan wheel to rotate atrela- V tively high speed whilevstill malntainlng a"- relatively low velocity of pressure.

Another object has been to provide a fan having blades so formed that they shall withstand the pull of the centrifugal force due to high speed of rotation without distortion, or Without the customary intermediate stiffening rings.

Moreover, because of the absence of stifi'ening rings or braces on the blades of my fan, the cost of manufacture, as well as the weight of the fan, is reduced, which in turn requires less power to drive, and, therefore, increases the resultant efficiency of the fan. 7

Furthermore, the blades of my fan are so formed that they have a general backward inclination, whereby the friction of the air passing through them shall be reduced to a minimum, and, also, the entering end of each blade is so formedithat the shock or impact with the, entering air is reduced to a minimum.

The above.- objects and advantages have been accomplished by the device shown in the accompanying drawings, of which:

Fig. 1 is a side, sectional elevation of my complete fan, showing, forclearness of i llustration, only two fan blades. I

"Fig, 2 is an endiviewof a'co'mplet'e blade,

the blade is formed. 3 isafsideeleva trated in Fig. Qfandit is a projection ofthe blade there shown. y i My' 'fan comprises a snail-shapedcasing 5. havingjan inleteye 6. Thecasingis', of course, provided with a tangentially arrangedoutlet, opening, which forelearness of illus trationis not'ishown. V

and shows diametricallythe manner in which 7 The wheel of my, 'deviceis represented at 10 andit is carried by asha'ft 11 which is rotatably mounted in aisuitablebeiaring' 12;

The wheel comprisesa'disc13 which is se-f curedto a hub 14. A ring 15 isprovided opposite thedisc lO ,-andthe blades 16 are arranged between and secured to the disc and ring. The ring' l5- i spreferablyi 'provided with an outwardlyturned flange 17 which is arranged over the inner end-fof aninlet cone 1 8;" This inlet cone'iscarried by;.the inlet eye 6 of the casing, Whereb'y'the air is directed into the center of the wheel. i

' Re er ing to Figs. 2 and s, it will beseen thatea'ch, of the bladesof my device is formed from the "surfaces of two tangential truncated cones 20and- 21, the line of contact of the cones being an element 'ofeach" cone; if The cones, and, therefore, each blade'isls'ocpost tioned thatfa line 222 3 drawn tangent 'to both cones at any point alon'gtthelline of con tact and in a'p'lane' whichis at right a igns to the" axis" of the? wheel is' oblique'toflaplane drawn through the axis of the shaft andco incident fwithla' point near "the tip oftheheelof the blade,said line intersecting said plane at a p'ei'ntbetween the axisof the wheelandthe tip tion of the thatillus of thefheel. I The blades are thus so formed and positioned, withffespect tothe rotation of'the wheel,-that the working surface of each recedes from the heel totlie tip thereof so that the air is expelled at a' gradually increasing acceleration. I Furthermore, the heel portion 26. ofthe-forWar'd' end 27 of the blade'is' formed coincidently with the smaller" diam I eter 28 of the cone 21 while: the tip portion 29" of the forward-@6127 of the blade'is formed from the smaller diameter of the cone 20.

' The heel portion 31'of the rear edge 3210f the l ferredgemb'odiment thereof.

blade is formed coincidentlyiwith the larger diameter 33 of the cone 21,While the tip portion 34 of this end of the blade is formed from the larger diameter 35 of'the cone 20'. The

cones 20 and 21'arefpreferably' so arranged that a line 40.-%l1, drawn thr'oughthe centers 1 i of the smaller circles 28- and 30-thereof is' parallel itha line 4l243 drawn through the ,centers of thelarger circles 3 3fland 35, re

spectiyely, of the cones. Thetip of the. blade ispreferably coplaner, Whilethe heel 46 thereof is preferably noncoplaner. V The heel 4:6 is preferably so designed thattheend47 T thereofwhich is farther from the inlet end of the wheel is in vadvance, in, the direction-of rotati0n,fof theend4l8 of the heel; It will be seen by. reference to Fig. 2, that each blade has ja forwardlycuryed heel 46 andfa backwardly c I Curved tip 45. In Fig. 2,,5 O5represents the vided with a, pluralit of blades, the sur:

faces ofeach blade being formed from por-' V tions of the surfaces of two cones, the cones being so positioned that their surfaces have substantial line contact, each blade being so inclined that a line drawn tangent tobothe cone" surfaces and in a plane at right angles to the axisof the wheel isoblique to a plane 1 drawn through the axis of the wheel and coincident iwithapoint near the tip of the lheel of the blade, saidline'intersecting said plane thetipof the heel, the tip of eachblade being substantially coplaner With'the. axis of the v wheel and the heel being substantially nonat ,a'point between the axis of the Wheel and coplanar'with said axis, andeach blade hav' ing a forward and backward curve,

In testimony whereof, I have signedinynam centerof the shaft lliaportionofthe disc 13, I

of the wheel'being sho Wn.

Obviously, some modifications of the details Therein shownland described; may ,be made, 1 Without departingfrom the spirit'of my ins Ventionorthe scope of the appendedclaims, i5 7 1 centrifugal: fan vhavingl giiwheel pro} with a plurality ,of blades, the sur,-

faceg'ofeach blade being formed from'porq i tions of'thesurfaces of,,-twofcones,. the cones being so positioned thattheir sur-faceshave substantial line contact, andleaeh blade beingsoinclined that.,ai line. drayvn tangent ito both cone surfaces and i-n aplane.atright' angles clinedthata line drawn tangent tovboth-cone surfaces and in a plane atrightvangles to the'" axis of thewheel isob liqueito a plane *drawn through the axis ofthewheeland coincident drawni'through, the axis of the flwheel and coincident with a- :point near' the "of the heelof thebladei, said line intersecting. said plane atapoint between theaxis of the wheel and-thetipoftheheel. if, v i f centrifugal fan having a wheel pro Yided with ;a 1plur ality;of blades, the surfaces 7 of 'eahhbliddbeing formed from portions of i tothe axis ofthewheel isoblique to arplane thegsurfacjesof'two cones,'ithe; cones being, I so ,p'o'sitioned that their surfaces have subf i 1 stantial'line ,contact,j each blade being so in- V with a point near the tip of vithe heel -,of the blade, line-intersecting said plane at a 7 point. between the axisof thewheel and the tip oflthe'heel, and the tip {0 each bl adebeing.

substantially coplanar-withltheya xisofthe 1- V Wheeland-the heel-ofeachblade being'sub f stantiall y non-,coplaneri 'w ithisaid axis. V V

ea ena i i al immensewhe ipr a' e a r ALBERT :AJORIQUII, 8 5

hereunto &

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