US1020725A - Centrifugal fan. - Google Patents

Description

ITNESSES: suwwv Able,

P. R. STILL. OENTRIFUGAL FAN. APPLICATION FILED JAN.14,1910.

1& 1.

INVENTOR l l): 1' [Ufa/71130,

Patented Mar. 19, 1912.

- UNITED STATES OFFICE.

FREDERICK R. STILL, 013 DETROIT, MICHIGAN, ASSIGNOR T0 AMERICAN BLOWER 1 COMPANY, OF GREEN ISLAND, NEW YORK, A CORPORATION OF NEW YORK.

CENTRIFUGAL FAN.

Specification 01' Letters Patent.

Application filed January 14, 1910. Serial No.

Patented Mar. '19, 1912. 537,987

'and arranged in drum form to inclose within them a relatively large intake chamber.

The object. of the invention isto strengthen such fans against centrifugal stresses when driven at exceptionally high speeds.

It has been customary in constructing such multi-blade fans to 'make the blades in one piece the length of the fan or drum, and to support them at opposite ends by riveting them to rings or arin-g and disk. In some instances the blades have been strengthened by applying a ring or rings exteriorly to the drum. It has been customary toemploy radial orslightly tangential stays or tie rods for centering the fan or drum and for resisting centrifugal stresses In some instances the blades have been divided longitudinally into two or more sections with a Hat ring between the sections to which they are riveted. According to the present invention the blade is divided into such sections,- preferably three in number, and pref erably of equal Ien th, and fiat rings are fastened between ,t e respective sections,

and instead of connectingthe usual stayspor tie-rods to the outer or end ring, they are connected to one of the intermediate rings in such manner that the centrifugal stress of r the sections on opposite 'sides of such ring is approximately balanced, and is transmitted through the ring and stays to the hub.

Referring to the accompanying drawing-Figure 1 illustrates a high speed fan embodylng my invent-ion applied upon a verticals xis as a ventilating an; Fig. 2 is a plant ereof partly in horizontal-section; Fig. 3;. shows the three sections of one blade and their connected rings and disk slightly separated; Fig. 4 is a fragmentary section, being an enlargement of a portion of Fig. 1;

Fig. 5. is a-horizontal sect-i0n, "being an en-' largement of a portion of Fig.- 2.

In the particular construction-shown in Fig. 1, the fan is applied for drawing air down through a deck, roof, or floor A through a tubular conduit or throat B. The fan wheel 0 is mounted on a vertical shaft D, the bearings forwhich are not shown.

The fan wheel comprises a hub a carrying a disk 6', the numerous blades E E which are disposed eylindrically or in drum form around the axis, and the customary end ring 0. Ordinarily the blades E E extend from the disk 6 to the ring '0. According .to the present invention the blades are divided preferably into three sections, lettered d e and 7 respectively, and which are preferably of equal length, so that in practice the same blade punchings can be used for each of the three'sections. Between these sections fiat rings g and h are introduced, and the blade sections are fastened to them in any suitable manner, usually by riveting through ears struck up from'the blade sections. The disk 7 .b is customarily formed partly as a flange cast upon the hub' and partlyas a fiat disk or ring 6. Thus the blade sections at are riveted between the disk ringl/ and the ring 9; thesections e are riveted between 1) the rin s g and h; and the sections f are riveted etween the rings h and c. Stays or tie rods F F are connected between the hub D and the ring h. These stays are connected tangentially to the hub (as in David- 5 son Patent,No. 691,609), so that they carry tensionally a considerable part of the driving stress or torque. Their principal functlon, however. is to center the fan wheel or drum and resist centrifugal stresses. Heretofore it has been customary to connect these stays F F to the outer or end ring a, so that the blades are supported only at their op 0- site ends. In fans driven at exoeptiona 1y high speed, it results that the middle por- 9B tions of the blades, being unsupported, tend to bow outward. subdividing the blades into sections and interposing the flat rings 9' and h which are shaped to resist centrifugal stresses, results in strengthening the blades, but with the old arrangement of stays the middle sections 0 ,are supported only through the terminal sections and in tervening rings. By connecting the stays to the. intermediate ring h, this ring is 105,.

strongly supported and centered. The centrifugal stresses communicated from the sections 6 and fon opposite sides of this ring, substantially balance one another, so that there is no unequal stress upon the ring, and v I the balanced stresses are transmitted. in the plane of the ring to the points at which the stays are attached. Thus eachblade section is connected at one end to a strong and rigidly centered support, namely,.to the disk I) or ring 72.,- the. opposite ends of the' blade sections being connected tothe rings. 9 and c which are supported and centered from Z) and it through the intermediationof .the.

blade sections,

As compared with the old construction, the improvement provided by this invention renders the fanv wheel or'drum from 8 to 16 times as strong in its resistance to blades. Another construction is to rivet bosses to the. ring having inward projec-- tions to which the stays are attached; but

this hasbeenfound to diminish the volume of air as much as 15 per cent. The present invention introducesv the outer ends of the stays intd the ports or spaces between the blades. As these spaces are somewhat narrow and with the usual curved blades are necessarily curved, it is preferableto make the flattened terminal portion 6 of the stay nearly as wide"- as ,will fill this space, and to curve it to conform tothe space or approximately so, as best shown in Fig. 5.- The blade sections 7 are customarily constructed a with ears turned up from them-through for the stay.

which the attaching rivets are passed. It is preferable to place the flattened portion 91 so as'to overlie these. cars, as shown in Fig. 4, and to form holes through it coinciding with those through the ears, and to utilize thesame rivets which fasten theears of bothsections f and e as the fastening also This affords a very strong construction which lends itself to the use of the .ordinary punchings for the-blade sec- .tions and the ordinary attachment therefor,

and avoids perforatingthe blades to' admit the passage of the stay rods. By avoiding any obstruction to the inflow of air italso conserves the maximum volumetric capacity of the fan. 4 a The drawing shows a fixed hood or casing G, and a hood or coneH for directing the blast of air from the fan.

I claim as my invention 1. A centrifugal fan having a hub or disk and numerous elongated blades arranged in centrifugal stress,

coinciding therewit drum form to inclose within them a rela tivelylarge intake chamber, said blades attached at one end to said disk, and a ring to which their opposite ends arev attached, said blades subdivided into sections with intervening rings to which they are fastened, and stays connecting saidhub to the inner portion of an intervening ring, said stays having their outer ends entering the spaces between successive blades and riveted to the rin 2. In a centrifugal fan of the multi-blade drum type wherein the bladesare divided into sections with an intervening ring, the blades having ears riveted to said ring, the combination therewith of stays for resisting centrifugal stress, having their outerends entering the spaces between adj aoent blades, overlying the. ears of a blade, having holes coinciding therewith, and rivets passing through said holes for fastening both the blade and stay.

3. In a centrifugal fan of .the multi-blade drum type wherein the blades are curved forwardly and are divided into sections With an intervening ring, the combination therewith of stays for resisting centrifugal stress, having their'outer ends flattened and entering the spaces between adjacent blades, and curved to approximately conform to such spaces, andrivets fastening saidflattened ends to said ring.

4. In a centrifugal \fan of the multi-blade drumtype wherein the blades are curved forwardly and are fastened to a ring at one end and a ring or disk at the other, the combination therewith-of stays for resisting centrifugal stress/having their outer ends flattened and entering the spaces between adjacent blades, and rivets fastening such flattened ends to the ring.

5. In a centrifugal fan of the multi-blade drum type wherein the blades are curved forwardly and are fastened to a ring at one end and a ring or disk at the other, the blades having ears riveted tosaid ring, the

. combination therewith of stays for resisting having their outer ends entering the spaces between adj acent blades,

overlying the ears of a blade, having holes and rivets passing through said holes for fastening both the bladeand stay. l

In -witness. whereof, I have hereunto signed my name in the presenceof twosubscribing witnesses. I a a FREDERICK R. STILL.

Witnesses T. CHESTER,

vC. H. TREAT.

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