USRE12798E - reissued mat - Google Patents

Description

No. 12,798. RBISSUED MAY 26, 1908.

s 0. DAVIDSON.

GENTRIPUGAL FAN OR PUMP. APPLIGATIGN FILED MAR. 16.1908.

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- s. 0. DAVIDSON.

OENTRIPUGAL FAN OR PUMP.

APPLICATION FILED MAR. 16. 1908...

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REISSUED MAY 26, 1908.

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REISSUED MA /2%, 1908.

- S. G. DAVIDSON.

GENTRIFUGAL FAN OR PUMP.

APPLICATION FILED LIAR.16.1908.

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d NZ No. 12,798.- REIS'SUED MAY 26, 1908. s. 0. DAVIDSON. OENTRIFUGAL FAN 0R PUMP.

-AJPPLICATI0N FILED MAR.16.1908.

' B SHEETS-SHEET 6 Y INVENTOR WITNESSES;

No. 12,798. REISSUED MAY 26, 1908.

S. G. DAVIDSON.

GENTRIFUGAL PAN OB. PUMP.

APPLICATION FILED MAR.16.1908.

8 SHEETS-SHEET lg. 11 Fi 14.

[MENTOR WITNESSES. I [1y Alla/12 m:

REISSUEDMAY 26. 1908.

s. 0. DAVIDSON. OENTRIPUGAUL FAN 0R PUMP.

APPLIGATION FILED MAR.16,1908.

a SH'EETSSHEBT 7.

INVENTOR WITNESSES: 5%; W

REISSUED MAY 26, 1908. s. 0. DAVIDSON. GENTRIFUGAL FAN OR PUMP.

APPLIGATION FILED MAR. 16. 1 908.

B SHEETS-SHEET 8.

INVENTOR UNITED 'sTArEs PATENT OFFICE.

SAMUEL CLEEAND DAVIDSON, OF BELFAST, IRELAND, ASSIGNOR TO SIROCGO ENGINEER- ING COMPANY, OF JERSEY CITY, NEW JERSEY, A CORPORATION OF NEW JERSEY.

CENTBIEUGAL FAN OR PUMP.

Specification of Reissued Letters Patent. Reissued May 26, 1908.

Original No. 662,395, dated November 27, 1900, Serial No. 691,495. Application for reissue filed March 16, 1908.

' "lcria1 No. 421,592.

DAVISION (J.

To all whom it may concern: a; Be :it known that I, SAMUEL CLELAND DAVIDSON, of Belfast, Ireland, have invented certain new anduseful Improvements in 5 Centrifugal Fans or Pumps, (Diyision C,') of which the following is a specification.

' My invention has reference to rotary fans or pumps in which the fluid operated on is taken in axially anddiseharged circumferen- 0 tially; and it relates to centrifugal fans or :pumps in whioh the blades carry the fluid -with them in their rotation, and thereby throw it outward 'by centrifugal force, as distin 'uished from propeller fans or pum s in wl'uch-the blades act upon the fluid witha The word blades is used to indicate the vanes or wmgswhieh impart motion to the 50 fluid. The expression intake-chamber is em )loyed to indicate a chamber or space inclosed within the series of blades. The word eye is used to designate theinletopening in the casing or stationary member of the fan, through which opening the fluid enters the intake-chamber. .By the in- I take end of the blades or ports is under- .stood that end which is nearest the eye. The. depth of the blades is their Width 40 measured radially from the inner to the .outer edge, the length of the blades is their axial measurement, and the. ports are the intervening spaces between the blades.

According to my invention the rotary member of the fan is constructed with numerous thin elongated blades arrangedin substantially drum form, being extended. in approximately axial direction, so as to inclose within them a relatively large and practically-unobstructed intake-chamber, and said blades in transverse section being arranged rela tivelyto the'axis and direction of rotation to .at an angle to each other with their outer.7

carry the fluid with them rotatively and discharge it tangentially, and said rotary mem- 'ber is so mounted as to permit the tangential escape of the fluid discharged from its blades. The blades are best made of sheet metal and are elongated-that is to say, their length approximates at the least three times their depth and being preferably as much as nine or more times their depthit being referable to make them as narrow or shal ow as practicable consistent with strength of con: struction. Preferably their inner and outer 65. edges are substantially parallel to each other. The blades must be so shaped relatively to the axis and direction of rotation as to carry the fluid withrthem in their rotation in order to throw it outward by centrifugal force, whereby it is discharged tangentially. To: this end the blades may be formed with a plane surface and arranged in radial planes or they may be made in'two or moreplanes 5 edges turned or inclined forward'-that is, in the direction of rotation-o'r they maybe formed as curved plates with their outer edges turned forward, so that the concave of said curve is on the forward or advancing side; this latter'construction being referred.

The blades are so numerous as to fo low each other in close succession, bemg spaced apart preferably a distance approximating two-' thirds of their radial depth. The drum-like arrangement of the blades .is such as to inclose within them an intake-chamber, which "preferably is approximately cylindrical and which is of large dimensions as compared with fans heretofore existing, that is to say, its diameter approximates at the least to four times the radial depth of the individual blades, and in the preferred proportions is live-sixths of the external diameterof the series of blades, and its length or axial dimension approximates at least three times the depth of the individual blades and in the prc l'crred proportions approximately nine times such depth.

\Vhen l employ: ngled or curved blades, I mount them so that while their concave faces are towardihe-direction of rotation their outer edges are tilted forward slightly, so that they have a lead in the direction ofTo tation relati'v'ely'to" their inner edges, whereby "1 05 the clear width of the ports between the blades at their outer edges is narrower 'ai'id' blades are attached at 'their ends remote from-the intake ends. A ring or annular supor intake endsof the blades.

The rotary "member'of the fan is suitably mounted to p the fluid disc ar ed from its blades. "If not "incased, this flui ermit-the tangential escape of can freelc'y escape from it-in all directions. If inclose latter must be so constructed as to permit the tangential escape of the fluid.as, for eXam-' ple, by forming the casing of the usual snail shape with a tangential outlet beyond the;

periphery of the rotar member.

"In the Operation 0 my new fanthe fluid i j flows in axial direction into the intake-chainber, in which it expands without percepti-' bly revolvi until it is caught by the "blades and rawn into the ports between them, whereby the fluid in these ports is converte d into a whirling) shell offiuid,jwhereby v it is thrown outward y centrifugal force and discharges from the outer sides of the orts as a whirling and expanding shellof flui the individual particles of which move in tangential direction; The blades are so narrow and so close to ether that no edd -currents are caused in t e ports between t em, thus avoiding the loss of efiicieiicy and the whir-' ring or beating noise accompanyin theoperation of centrifugal fans as hereto ore made.

In my preferred construction the intake ends of the blades are open to the infiowing fluid, so thatlthe fluid the intake ends of the ports. Iii this case I make the eye or intake opening in the casing leadingto the fan of a diameter e ual, or ap-' proximately so, to the full outer diameter, of the .dr'uni-sha ed series of blades, whereby the volume 0 fluid'which will be propelled through "the fan for a given diameter and speed of revolution is proportionately in creased without'loss of velocity in the flow of the fluid.

My improved fans or umpswhen con structed as herein descr ed may be employed with any fluids, either gaseous or uidas, for instance, with air or water.. n the; accompanying drawings, Figure 1 is a sectional elevation on theline 1-1 of Fig.

2, illustrating the preferred embodiment of my invention'. Fig. 2 is a cross' sectional elevation thereof. Fig. 3 is a'fragmentary detail view, showing a portion of the blades shown in Fig.1 on a larger scale. Fi 4 is a "detail cross-section taken at the inta e jends. .Ofthe blades, showing the method of attac'hin a casing, the.

.as in Fig.

may flow, axially into ing their 'outer edges to the connecting ring. Fig. 5 is a similar detail view to Fig. 4, showtake end, Fig. 7 being a rear elevation, Fig.

shown in Figs. -1 and 2 with spoon-shaped iii-- 8 an outer edge view, Fig. 9 an end view,

Fig. 10 a cross-section, and Fig. 1.1 a perspective view. 'tional elevations, respectively, of the lower and up or half of the fan with two formsof angleades. Fig. 13 is a sectional ,eleva tion of the fan with flat blades'in r ial' planes. Fig. 14 is a sectional elevation of the fan with curved blades in'a modified proportion. Figs 15, 16 and 17 are detail Figs. 12'and l2 are secveiws, on 'a larger scale, of ablade formed in two planes, as in Fig. 12. Figs. 18,, 19 and 20 are similar views of-a blade formed in three planes, as in Fig-12. Figs. '21, 22

and 23 are similar views of a curved blade, 14, with spoon-shaped ends. (Figs. 24-27 of my original atent are Jiere omitted.) Fig. 28 is a vertical axial section of i a modification, showing an uncased fan or exhauster.

Referring to the drawings, a in Figs. 1, and 2, designates a casing in which the rotary member of the fan is inclosed. It has an eye 71,, Fig. 2, through which the supply of fluid is drawn, and is shown with a dischargingmouth iece g. The rotary member come. prises lades c c, suitably supported upon a revolving shaft or spindle The support shown comprises a disk to which the blades are attached at one end, and an annular su port for the opposite or intake. endsof tie blades. In Figs. .1, 2, 4 and 14 this sup i'ort is formed by a ring (1 to which the inta e ends are riveted. T e blades 0 c ha'veat one end flanges c, by which they are attached to the disk I), y' j being holes in said 7 flanges to give passage .to the rivets or atf taching-deyices. At the intake ends of the blades they may have flanges 0 by which they are attached to the ring (1 in the manner shown in Fig. 4, orby rolonging the flanges 0 as shown in Fig. 6, th y may he rive-ted or attached to each other in the manner shown in Fig. 5. .The flanges a have holes 7.: 7c to give passage to therivets or attaching devices. Theforward'ly-tilted spoon-shaped intake ends of the blades are designated at Z. The ports or intervening spaces between the blades are lettered e e. In Fig. 3 it'will be noticed that the widthof these ports at m, near theouter edges of the blades, is somewhat less than at 3;, their inner edges, owing to said outer edges of the bladesbeing tilted slightly forward relatively to the radial line z. By thus turning forward the outer edges of the blad esthe-outer or discharging area of the ports is reduced to less than their inner or inlet area. The same result may be attained with angle-blades, as shown, for eX-- ample, in Fig. 12*.

In proportioning the parts I make the length ofthe blades such that the aggregate open area of the ports around theperiphery of the fan shall be at least equal to the area of the inlet-opening when. the maximum volume of intake and discharge is required; but the length of the blades may be varied to suit any special requirements.

The preferred proportions of my fan are .shownln Fi s. 1 and 2, where the radial depth of the lades is one-twelfth of the di ameter of the fan and the length of the blades is nearly nine' times their depth. This construction afiords a large intake-chamber of approximately cylindrical form, the diam.- eter of which is ten times the depth of the individual blades, while its length, equaling that of the blades, is about nine times this dimension. The blades. in Figs. 1, 2 and 3 are shown's aced apart a distance approximating onealf their radial depth.

The provision of a relatively large intakechamber in connection with shallow blades following each other at frequent intervals is a distinctive feature of my invention. as ordinarily constructed, employing blades of great radial measurement, supplementary vibrations and eddies are set up, which reduce the elficiency of the fan. In those fans also in which the blades are extended inwardly to or near the axis the best elliciency is not obtained. ,1 have discovered that by providing a relatively large intake-chamber ractically unobstructed by the projection into it of blades or other parts and by'em ploying blades which extend as short a distance from the periphery of the fan inward as is consistent with strength of construction the said supplementary vibrations and eddies are minimized and the velocity and volume of fluid discharged for a given speed of revolution. are greatly increased.- Y

The blades may be :[lat and in radial planes, as shown in Fig. 13, or they may be bent angularly into two or more planes, as shown in Figs. 12 and 12*, or they may be curved, as shown in Figs. 1 and-3, the curved form being preferable. The depth. of the blades may be increased to the extent shown in Fig. 14, i where the intake chamber is reduced to a dlameter four times the depth of the iniilivid ual blades. a

- "It has hitherto been considered impossible to get pressure or partialeiihaust with centrif ugal fans'unlessthe' blades are inclosed on the sides and the eye or o'peningis of not greater diameter'than aboutondsa If the di- In fanswith them rotative ameter of the fan.- With my present invention, however, the eye may be of equal diameter to that of the fan periphery. This is clearly shown in Fig. 2. This is made possible by making theintake ends of the blades open or unobstructed, so as to form open ended ortsbetween them. To support and strengthen the intake ends of the blades, I prefer to make them laterally curved or spoon-shaped or"concavo-conveir, as shown at Zin Figs. 6 to '11;

It is obvious 'that 'in the fanor pump shown inFigs. 'l and 2-and alsoin. others (shown, res actively, in Fi 14 and in those shown in lhgs. 2 14;027 inclusive) the casin (1 may project inward over the edges of the blades .1: a, but the inlet-opening or eye to the fan should not be thereby reduced to less than five-sixths of the diameter of the fan. 1

In all the modifications thus far described the fan is within a casing. lit'will, however, be readily understood that a casing is not necessary in all instances as, for instance, when the infiowing fluid is led to the eye'of the fan by-apipe, or when the fan projects through an orifice in a wall, so as to revolve,

say, outside a house with the eye of the fan facing the hearings in which the spindle revolves. draw the air through that iorifice and discharge it freely all'aroundinto the open air.

This modification is shown in Fi 28, where o is a pipe leading to theeye h oft e fan, and m is the wall of a building, through which this pipe passes to lead the air to the rotary member of the fan, the driving-shaft f being supported in a bearing 1). It is essential to my invention that the fanblades shall be adapted to carry the fluid so that it shall be thrown outward by centrifugal force and be discharged tangentially, in contradistinction to merely exerting a wedge-like action u on the fluid, tending to thrust it outwar in radial direction unaccompanied by any material rotation or whirling of the fluid. In a true centrifugal fan it is almost solely the rear surface of the blade which acts upon the fluid, drawing it around by suction, whereas in blades which thrust the fluid outward by a wedgelike action it is the front or advancing side of theblade which is the active face. Blades of the latter kind require to be inclined or curved rearwardly to a considerable angle, especially at the outer edge, which follows behind the middle or major portion ofthe blade. in transverse section arranged, relatively to the axis and direction of rotation, to carry the fluid with them rotatively and discharge it tangentially .to exclude such wedging blades and include generically any form of blade adapted to act upon the air by rotating or whirling it, thus including blades which The fan when driven would then I use the expression 'whirling fluid discharged from escape tangentially therefrom in outward.

are substantially radial, was well as those which incline forwardly, and either flat, curved, or angled.

airas accompanied by the existence of a thin shell-,or film of rapidly-whirlin air immediately surroundingthc drumike series of blades, which air is ap arently com ressed, and outside of this she l'the air disc arging from the fan escapes tangentially. Whether the fan is provided with a casing or not the construction must be such. as to permit the direction.

To realize the full advanta es of my invention, it is practically essentia that the inflow .of'fluid to the intake-chamber be unobstructed and that the inlet-opening be' of the full diameter of said chamber, as any throttling of this opening results in a proportionate diminution of volumetric efficiency. It is also practically essential that the whirling fluid discharged from the fan-blades shall bepermitted to escape tangentially outward therefrom, as any attempt to divert the revolving fluid .inwardly results in a rat id diminution of efficiency; fluid can be collected in a casing-and if the outlet from this casing be arranged beyond the radius of the circle described by the outer through said outlet,

edges of the blades the fluid will freel-yescape its whirling motion being' thereby resolved into a direct motion, after which it can be led through asuitable conduit inany desired direction.

The fan provided by my resent invention is distinguishedfrom that s own in Fig. 7 of 'my United States PatentNo. 544,758, wherein the blades are triangular and project'into the central hub, that in my present form the blades are extended approximately parallel 7 arranged in to theaxis of rotation, being drum form, so as to inclose within them an approximately cylindrical intake chamber which is practically unobstructed by blades or otherparts. Y I

The modification shown in Fi 13, wherein the blades are flat and radia is not spe'' my application, Serial No. 17,366, filed May 21, 1900(Patent No. 662,397, dated Nov. 27,

I 1900) which alsoisa division of my present 'abplication.

he operation of my fan when propelling the blades to' but the whirling.

application, Serialature being so claimed in.

I The present reissue (Division C):of'my original Letters Patent is. directed to that feature of my invention which is characterized by the blades being open at their intake ends '(being preferably curved transversely .at

their intake endsto' stiffen them) .irres'pec? tive of the shape of the blades in cross sedtion. Except Where the blades are thus open at their intake ends'I make no claim in my present reissue to that feature of my in vention whichis characterized by the provision of a relatively large intake chamber with nu mero'us elongated lades which are so narrow radially and so remote from the axial center that their inner edges revolve-at a-pe.

ripheral speed so nearly approaching that; of their outer edges that fluid is drawn in at their inner edges at approximately the same rate'as it is discharged romtheir outer edges; or, otherwise stated, that the ports'between the blades are not materially wider at their exterior or discharge ends than at their inte-.

rior orinlet ends, this being claimed in another reissue (Division A) of my said originaLLetters Patent.

- Also except where the blades are thus open at their intakeends I make no claim in my present reissue to those features of my invention which are characterized by the inclining of the outer edges of the blades forward or in the direction of rotation, to

such effect that the outer width of the ports between the blades is no greater (and is preferably less) than their interior or inlet width and by the employment of curved blades "with their outer edges so inclined forward and which are concave on their advancing sides; these being claimed in another reissue (Division B) of my said original Letters Patent.

I claim'as my invention the following defined novel features, substantially as hereinbefore specified, namely:

1. A centrifugal fan or pump, comprising a rotary member having numerous elongated 1 blades arrangedlengthwise in approximately axial direction, and in substantially drum 'form, so as tovinclose within them a relatively large and practically-11110bstructed intake chamber, and in transverse section arranged relatively to' the axis and directionof rotation, to carry the fluid with them rotatively and discharge it tangentially, the ports between said blades being open at their intake ends, and a means for so mounting said rotary member as 'to permit the-tangential escape of the fluid discharged. from said blades. I

2. A centrifugal fan or pump, comprisinga rotary member having-numerous elongated blades arranged len thwise in approximately axial direction, an in substantially drum form, so as to 'inclosewithin them arelatively large and practically-unobstructed intakechamber, and in transverse section'arranged,

' relatively to the axis and direction of rotation, tocarry the fluid with them rotatively, and discharge it tangentially, the ports between said blades being open at their intake ends, the blades being narrow radially in proportion substantially as set forth, and i a means for so mounting said rotary member as to permit the tangential escape of the fluid discharged from said blades.

3. A centrifugal fan or pump, comprising a rotary member havin numerous thin elongated blades arranged lengthwise in approximately axial direction, and in substantially drum form, so as to inclose within them a relatively large and practically-unobstructed in.take-chamber, and in transverse section arranged, relatively to the axis and direction of rotation, to carry the fluid with them rotatively and discharge it tangentially,the ports between said blades being open at their intake ends, and the blades spaced. apart a distance no greater than twice their radial depth, said blades being inclined forwardly in the direction of rotation to such effect that the outer or discharging width of the ports between them is not greater than their interior or inlet Width, and a means for so mounting said rotary member as to'permit the tangen' tial escape of the fluid discharged from said blades.

4. A centrifugal tan or pump, comprising a rotar niember having numerous elongated b ades arranged lengthwise in approximately axial direction, and in substantially drum form, so as to inclose within them a relatively large and practically-unobstructed intake ohamber, and in transverse section arranged, relatively to the axis and direction oi rotation, to carry the fluid with them ro tatively, and discharge it tangentially, the ports between said blades being open at their intake ends, and having an inlet opening to said. chamber of diameter approximately equal to the external diameter of the series of blades, so as to admit the inllowing fluid into the open ends of saz-zz rwrts.

5. A centrifugal fan or pump, comprising a rotary member having numerous elongated blades arranged len thwise in approximately axial direction, 5111C in. substantially drum form, so as to inclose within them a relatively large and practically-unobstructed intake-chamber, and in transverse section arranged, relatively to the axis and direction of rotation, to carry the fluid with them rotatively and discharge it tangentially, the ports between said ljlades being open at their intake ends. and an annular support for the intake ends of the blades, such gaging the outer edges thereof.

6. A centrifugal fan or pump, comprisin a rotary member having numerouselongate blades arranged lengthwise in approximately axial direction, and in substantially drum form, so as to inclose Within them a relatively large and practically unobstructed in-' take-chamber, and in transverse section arsupport enranged, relatively to the axis and direction of,

to carry the fluid with them rotatively and discharge it tangentially, the ports between said blades being open at their intake ends and the stationary member having an eye through which the fluid is drawn, concentric with said intake chamber and of a diameter a proximately e ual to the external diameter oi the series of b ades,soas to admit the intlowing fluid into the open ends of said ports.

8. A centrifugal fan or pump, comprising a rotary member having numerous elongated blades arranged lengthwise in approximately axial direction, and in substantially drum form so as to inclose within them a relatively large and practically unobstructed in take-chamber, and in transverse section arranged, relatively to the axis and direction of rotation, to carry the fluid with them rota tively and discharge it tangentially, said blades formed as curved plates having their outer edges turned forwardly, the ports between said blades being open at their intake ends, and the blades being curved transversely in spoon-shape or concavo-convex form at their intake ends to stifien them.

In witness whereof I have hereunto signed my name in the presence of two subscribing witnesses.

SAMUEL CLELAND DAVIDSON. Witnesses GEORGE GooLn WARD, GEORGE HENRY OSWALD Srmox.

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