US2385070A - Fan - Google Patents

Description

Sept. 18, 1945., L GANT 2,385,070

FAN

Filed Oct. 8, 1941 INVENTOR. L 65 lie 60/77 A TTORNE' Patented Sept. 18,1945

UNITED STATES PATENT OFFICE r 2,385,070 H t FAN Leslie Gant, Denver, Colo.

Application October 8, 1941 Serial No. 414,107

1 Claim. (Cl. 170-159) This invention relates to air screws and fans of blade type, and has as an object to provide an improved and highly eflicient construction and arrangement of blades in and for such devices.

A further object of the invention is to provide an improved fan designed to move relatively large volumes of air in proportion to the power required to actuate the fan.

A further object of the invention is to provide an improved fan blade susceptible of operative association with an axis of rotation to move relatively large volumes of air in proportion to the power input to'the' fan and along paths substantially parallel to the axis of blade rotation.

A further object of the invention is to provide an improved fan bladesusceptible of rotation about an axis adjacent one of its ends to generate and maintain flow of engaged fluid along a substantially cylindrical path axially coincident with the axis of blade rotation.

A further object of the invention is to provide an improved fan blade susceptible of convenient manufacture from available material in units of relatively light weight.

A further object of the invention is to provide an improved fan blade adapted for either fixed or adjustable association with a hub in such number and specific arrangement as may be best suited to a given purpose or installation.

A further object of the invention is to provide an improved fan blade designed to entrap and efficiently redirect fluid disturbed by rotation thereof about an axis adjacent one end of the blade.

My invention consists in the construction, arrangement, and combination of elements hereinafter set forth, pointed out in my claim, and illustrated by the accompanying drawing, in

which- 7 Figure 1 is an elevation of the output face of a four-blade fan constructed in accordance with the principles of my invention. Figure 2 is a perspective view of the construction and arrangement shown'in Figure 1. Figure 3 is a side elevation, on an enlarged scale, of the construction and arrangement shown in Figure 1, certain of the elements being broken away to conserve space. Figure 4 is a fragmentary, detail section,

on an enlarged scale, taken transversely of one of the improved fan blades on substantially the indicated line 4-4 of Figure l.

The instant invention resides primarily in a novel fan blade construction and in the operative relationship of a plurality of identical such blades with an axis of rotation; the specific number and mounting of such blades in a given fan assembly being immaterial to the inventive concept residing in the blade. I In the construction of the improvement as shown, the numeral l0 designates a shaft whereof the longitudinal center line is the axis of rotation about which the improved blades are to revolve as a fan. The shaft l0 may be the driven shaft of a prime movensuch as an electric motor, internal-combustion engine, or the like, or

said shaft may be independently mounted and supported for rotation deriving from such prime movers through suitable driving connections. A hub I I, conventionally illustrated, is fixed to and for rotation with the shaft Ill and carries, a plurality of radial lugs I2, or equivalent means, in thisinstance shown as four in number, whereto the improved fan blades are secured at their innner ends in either fixed or adjustable relation with the hub, one such blade being mounted on each of the lugs l2.

The improved blades, regardless of their number or specific mounting in a given fan assembly, are identical and are uniformly spaced about and in identical relationship with the hub l l and shaft l0. Each of said blades consists of a flat, relatively thin, smooth web [3 tapering from a narrower end adjacent the hub II, to a wider end remote from saidhub, and an integral, smooth flange portion l4 forming asomewhat obtuse angle with its associated web l3 and tapering from a wider end portion adjacent the narrower end of said web to substantiallymerge into the plane of-said web at the wider end of the latter. The angle between the. web I3 and flan e 14 of each blade will be alike in all of the blades of a given fan assembly, .but such angle may be varied somewhat to most efficiently meet the requirements of a given fan and a given speed of fan actuation, but in no event should such angle, within the contemplation of this invention, be less than ninety degrees.

v The improved blades are fixed to the lugs l2, or otherwise mounted on the hub I I, so as to extend substantially radially from said hub with their wider web ends remote from the hub, with the planesoftheir webs l3 forming a small angle withaplane perpendicular to the shaft axis, and with the unfianged margin of each web l3 disposed as a leading edge in the direction of fan rotation. The leading edges of the webs 13 may be positioned radially of the shaft I0, but for enhanced efiiciency it is preferred that the outer ends of the fan blades be moved axially of the shaft [0 to define a plane of rotation spaced from the plane of rotation of their inner ends in the direction of their flanges M, as is clearly shown in Figure 3; While the blades are shown as mounted and positioned by means of engagement of the inner ends of their flanges M in slots formed in the lugs I2 and pins or rivets extending through said lugs and the engaged flange portions, it is to be understood that such mounting means is in no sense limitative, but merely typical or any means for suitably engaging the blades in operative relation with the huh I I.

With the web portions of the blades related to ther advantageous efiect in that the travel of said flanges, coupled with the flow of air outthe hub in the manner shown and above dee mon to the shaft axis, and the flangedsides oi.

wardly across their leading faces, creates a suction efiect immediately behind their trailing 'faces which operates to induce a flow of air through the fan and between the blades thereof, which induced air flow mingles with and amplifies the positively-generated currents from the directly-engaged blade elements. In similar manner, the rearward inclined face of the webs [3 function to induce air 110W into and between the fan blades, thereby perhaps initiating and certainly enhancing the induced flow past and behind the flanges M.

the blades constitute the output side or the fan.

web lg in trailing relation, in the direction of fan rotation, with their narrower inner ends,

which is a' modification within the contemplation of the invention, but such change would in no wa alter the construction and operative. principle of the improved blades nor vary the disposie can of the blade webs and flanges relative to the air be acted upon,

as will be apparent, the angular relationship between the web l3 and flange [4 of each blade is area atthe time of blade construction, and any rotation of a mounted fan blade. about an ass radially of the shaft l0 serves to simul-. taneously vary the pitch angle of the. web l3. and the relation between the flange l4 and a plane radially ofthe shaft. When the. blades are non-.5 adjustably f xed to the hub l lj, the free margins of the flanges I4 should not be advanced, in the direction of fan rotation, ahead ofthe junction of said flanges with their webportions, and when the blades are mounted for. adjustment. of their pitch angles, such adjustment. should permit a maximum pitch angle, of the webs l3. no. greater than will dispose the flanges. 1A in. the radial planes of the shaft as above set forth.

When the shaft H1, carrying the improved. fan blades constructed and arranged as shown and described, is rotated in the. direction of the. 31 row in Figure 1, the leading, unflanged margins (ii the Webs. I 3 out into the air with little re-.

sistance andthe flat faces of the webs, being disposed at an angle with the plane ofrotation, tend to compress theair engaged. thereby and initiallyurgesuch engaged air in a direction. pare alll to the shaft axis. Some of the air en a ed by the inclined webs 1 3 is deflected." forwardly, impinges against thev cor-responding flan e. L4 and. is thence deflected again, in the manner shown. by the. arrows Eigure: 4., to leave the blade with enhanced velocity in a. directionsube stantially perpendicular to the lane oirotation. m of the. r ged by the Web I3; 01? a. iven blade is temporarily trapped and compressed in the an le between. the web and associated flange lg i, whence it escapes outwardlvpast. an to. some extent about the free margin of said flange in a stream of high.- velocitydirected substantially perpendicular to, the plane of blade rotation. The action of theflanges i l-has a fur.-.

description.

In addition to air travel and reaction transversely or the fan blades, the mass of the engaged and compressed air reacts to the centrifugal forces developed through blade rotation to generate-air flow longitudinally of and outwardly along the blade elements. Were the outer ends oftheblades in the same plane. of rotation with their: inner: ends, the. centrifugally-induced air flow might be. wastedin a jetting action past the blade tips, but when the blade. outer ends are ad? vanced relativetotheir inner ends, in the manner shown, and described, the inclination. of the blade web I3- acts on the longitudinally=moving air to deflect the flow forwardly and into the. output stream from the fan, in much the manner indicated bythe arrows. in. Figure 3. A further advantage is developed through advancing of the blade. outer ends relative to their inner ends, in that the'effective input area of the fan is thus given conical form with a consequent extent greater than. would obtain were such area a plane disc of: corresponding. diameter.

When used as' an air-circulating fan or blower, the flanged 'outputside of the blades is. normally positioned todirectain away from. the fan mount.-

ing and primemover, whilauseof: thefan for the propulsion of aircraft or boats, normally requires a mounting such. as will direct theair or fluid stream from the fanrearwardly oft-he-craft tobe moved.

. Since many. changes, variationsv and modifications in the specific form, construction, arrange-. ment and combination ofwthe. elements shown anddescribed may behadwithoutdeparting from the spirit and: principle.ormy'invent-ion, I wish to. be. understnodasbeing limited solely by the scope of the appended claim, rather than by. any details of' the. illustrative showing and ioregoing I claim as my invention:

In a fan; or the. character described; a. blade formedtw-ith. a tapered-flat-weh portion longie. ti-idinally inclined at an. angle ,tojrts axis of rota: tion, and disposed withits. wider end outermost to form an angle with its plane of rotation; and a. trianneularflan e inte ral; wi l z-th trai i edge ofvsaidvweb pcrtieacn the si .oith latt r forming;- an; acuteansl sw t e armis ice and; disposed with. its: 1; a; adiace the inner end cf saiawebmrti'c in shah. obisag a s relationwith the nla ieoi th letter-as n no... the dance sutsian ialh a p ane adie .e he rotationalaxis

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