US2342421A - Fan and fan blade structure - Google Patents

Description

Feb. 22, 1944. R, D. MOORE FAN AND FAN BLADE STRUCTURE Filed Aug. 22, 1940 3 Sheets-Sheet l 'INVENTOR 1 Faber) Q Mqare.

Feb. 22, 1944. MOORE FAN AND FAN BLADE STRUCTURE Filed Aug: 22. 1940 3 Sheets-Sheet 2 INVENTOR Faber? 0, Naore.

Feb. 22, 1944. R. D. MOORE FAN AND FAN BLADE STRUCTURE Filed Aug. 22, 1940 3 Sheets-Sheet 15 0 m0 M 0 3 w 0 EV OR'NEY Patented Feb. 22, 1944 mum FAN BLADE STRUCTURE Robert D-MOOIB, Kansas City, Mo., assignor to J. F. Prltchard and Company, Kansas City, Mo., a corporation of Missouri Application August 22, 1940, Serial No. 353,599

8 Claims.

This invention relates to fans, and more particularly to fans for cooling towers, for example, of induced draft type. the principal objects of the invention being to provide a convenient, relatively economical and highly efficient fan structure of the character noted.

Other objects of the invention are to provide a fan structure of stressed skin fabrication; to provide a fan structure that is resistant to deterioration usually caused by collection of acids and solids deposited out of fluids acted upon by the fan; to facilitate assembly and disassembly of the fan structure; to decrease wind resistance of fans of this type; to support the fan structure in an improved manner; to provide for varying the pitch of the fan blades, and to provide improved elements and arrangements of them in a fan structure of the character and for the purposes noted.

In accomplishing these and other objects of the present invention, I have provided improved details of structure, the preferred form of which is illustrated in the accompanying drawings, wherein: I

Fig. 1 is a vertical cross-section through a motor housing, fan hub cowling and fan blade housing, showing the relation of my improved fan structure thereto.

Fig. 2 is a plan view of my improved fan structure, the cowling being shown in horizontal section.

Fig. 3 is a detail perspective view of a fan blade embodying features of my invention, the blade being partly broken away to better illustrate its structure.

Fig. 4 is an end elevational view of the fan blade showing the curvature of related portions thereof.

Fig. 5 is a detail vertical transverse crosssection through the blade on the line 55, Fig. 3, showing its inner end closing casting.

Fig. 6 is a detail perspective view of a blad bracing stringer connection.

Fig. 7 is a detail perspective view of a spoke for supporting a fan blade, part thereof being broken away to illustrate its interior construction, and an end closing casting being shown in disassembled relation thereto.

Fig. 8 is a detail vertical cross-section on the line 8-8, Fig. 7.

Fig. 9 is a detail vertical cross-section on the line 9-9, Fig. 7.

a Fig. 10 is a detail perspective view of the spoke I and blade supporting hub for the fan structure.

Referring more in detail to the drawings:

I generally designates a fan structure embodying the features of the present invention, which, preferably, includes a motor housing 2 that is suitably supported, as by a plate 3, and beams l in supporting and surrounding relation to a motor 5 that has a preferably fluted drive shaft 6 projecting from the motor housing.

to, Fig. 10, designates a hub having a key-way I engageable with the flute or key on the drive shaft, provision being made, as at 8, for securing the hubto the shaft. The hub is preferably provided with annular guide flanges 9 and I0 adjacent its ends to fit within a cylindrical hub channel I I, Fig. 1, of a cowling 12, the hub channel having a transversely arranged connecting plate I3 provided with fastening devices l4 engageable in apertures l5 of the hub flange III to secure the cowling to the hub.

The cowling is of generally cylindrical shape and of suitable dimensions having a diameter approximately that of the motor housing, the cowling being closed at its ends about the channel II by end ,plates l6 and I 1 that are preferably dished in the direction of the motor housing, as shown, to, in effect, streamline the cowling.

Radiating from the hub channel of the cowling are a plurality of spokes l8, Figs. 7 to 9, each of which preferably consists of reinforced stressed skins. More particularly the spokes consist of substantially duplicate plates 19 of sheet or like metal and of generally rectangular conformation, bent longitudinally on the lines 20 substantially at right angles to each other and having inturned suitably connected edges 2| and 22 to secure the plates in spoke forming shaped condition. The spokes are welded or otherwise secured to the cowlin as shown at 23, Figs. 1 and ,2, and have longitudinally arranged, preferably Z- shaped stringer reinforcements 24 and 25 on the inner faces of the bottom wall 26 and leading edge side wall 21 thereof.

Similar reinforcing shapes 28 are also preferably arranged longitudinally and horizontally ad- Jacent the outer ends of the spokes on the outer face of the leading edge walls 21 and spaced vertically arranged shapes 28, 23, 30 and 3| are mounted transversely on the outer faces of the bottom with 26, leading edge side wall 21, top wall 32 and rear side wall 33 of the spokes, the outer flanges 34 of the shapes preferably extending outwardly away from the cowling hub channe Mounted in the outer end of each spoke and closing the same is a casting, bulkhead or contom and side walls 33, 31 and 38, engageable within the corresponding walls of the spokes defining their outer ends, the connecting member preferably'being transversely braced, as at 39, and having a threaded socket 40 opening outwardly from a circular bearing plate 4| having an inwardly offset outer face to form a shoulder 42 on the plate, the shoulder extending outwardly relative to the side walls of the cowling, as shown in Figs. 1 and 2.

The plate 4| of the casting 40 seats a bearing ring 43, Fig. 3, on a casting, bulkhead or connecting member 44 that closes the end of a fan blade 45, the ring being apertured, as at 46, to receive the threaded shankof a bolt, Fig. l, and allow its passage into the threaded socket of the connecting member 35 for attaching each connecting member 44 and blade 45 to a spoke. The connecting member 44 has an aerofoil streamlined cross-section, as shown in Figs. 1 to 5, and determines the surface contour of the blades at their inner ends, the inner ends of the blades being curved concavely to generally correspond to the periphery of the cowling, as shown at 46, Fig. 2.

The fan blades 45 have a relatively flat compression or air pushing edge 41 and a streamlined lifting edge 48, the edge being relatively steeply inclined at its lead end 49 and having a gradual taper at its trailing end 50. A substantiall rectangular brace member is arranged on the inner face of the casting 44 and has inwardly directed top and bottom bracing flanges 52 and 53 following the contour of the wing or blade to be built around it. End braces 54 and 55 diverge laterally from the ends of the brace member 5| and are themselves braced at their lower ends by flanges 56.

The blade 45 is of stressed skin fabricated structure, that is to say, sheets of suitable smooth, rolled metal, such as stainless steel, Monel metal, bronze, steel, etc., are drawn firmly about the casting 44, the edges of the sheet being suitably secured together preferably at the trailing edge of the blade soformed.

Reinforcing stringers 51 and 58, preferably of angular cross-section, are mounted longitudinally, as by welding, on the inner face of the blade forming sheets in spaced relation to form reinforcements, as shown in Figs. 2, 3 and 5, when the blade has been fabricated.

In Fig. 6 a stringer spacing and bracing device 59 is illustrated, which preferably includes a plate edge provided with laterally directed arms adapted to be secured in supporting transverse relation to a pair of adjacent stringers 51 on the flat upper blade wall. The ends of the plate 59 diverge and terminate in ears 63 and 64 having lateral arms 65 and 66 adapted to be secured in supported relation to spaced stringers on the curved bottom wall of the blade. Intermediate ears 6! and arms 68 extend from the bottom edge of the plate 59 and all serve to connect the top and bottom stringers to produce a rigid fan blade structure.

The blade forming sheet is originally cut on a suitable taper at its side edges and the stringers are so arranged on the sheet as to form a blade having an outer end of reduced width relative to its inner end, the smaller end being closed by an end plate, bulkhead, or like of the same general shape as the casting, or connecting member 44 but of smaller size, the castnecting member 35, 7, which has top, bot-.

ing 10 also beingarranged at an angle to the horizontal less than the casting 44 in such a manner as to give the blade a twist as shown in Figs. 3 and 4. The casting l0 and outer end of each blade is also curved on an arc corresponding to the curve of a ring-like Ian blade housing 12 in order that the blades may be made of a length reaching substantially from the cowling to the fan housing, and thus increase the efficiency of the fan.

In order to facilitate assembly and disassembly of the fan blades relative to the cowling, a well 13, Figs. 1 and 2, is provided in each fabricated blade adjacent the inner end of each casting 44 and in alignment with the inner end of the bolt aperture 46 relative to the blades. The wells are of a diameter of approximately the depth of the threaded sockets 40 in the connecting members 35 to the end that the bolts 41 may be applied to both connecting members 35 and 44, as shown in Fig. 1, in such a manner that the heads of the bolts are exposed in the wells. The bolts may thus be manipulated to secure the blades to the spokes.

Sponge rubber liners 15 or the like are preferably mounted between'the inner ends of the blades 45 and outer periphery of the cowling to compressibly seal the space therebetween.

The blades may also be adjusted angularly from the horizontal relative to the spokes by the bolts in a simple manner to vary the pitch of the blades.

The blades may also be disassembled relative to the spokes by manipulation of the bolts without the necessity of dismantling the fan ringhousing 12 or motor and motor housing.

It is believed that the operation of a fan structure constructed as described is readily understandable, it being apparent that with the apparatus arranged as shown in Figs. 1 and 2, air will be drawn from below the fan ring-housing 12 and pushed upwardly past the motor housing. Should it be desired to change the pitch of the blades, the bolts 41 are accessible in the wells 13 and may be loosened so that the angles of the blades may be changed, the bolts then being tightened to hold the blades in their new relationship.

If desired, the blades may be removed for cleaning or repair by the simple expedient of removing the bolts from engagement with the castings 35, whereupon the blades may be lifted out of the fan ring-housing.

The stressed skin fabrication of the blades makes them lighter and thus easier to handle, either by hand or the motor, and the bracing arrangement gives them sufilcient rigidity to withstand great pressures and do Whatever work is reasonably required of the fan.

The relative smoothness of the outer. blade surfaces keeps wind resistance to a minimum, and the acid and=alkali resistant skin" greatly prolongs the life of the fan, particularly in cooling towers where recirculation of water to be cooled increases deteriorating deposits on conventional fan blades.

The cowling l2 may also be removed from the drive shaft without disturbing the hub 6A by simple manipulation of the bolts M which are accessible from open end of the cowling channel.

It is apparent, therefore, that I have provided a convenient, relatively economical and highly What I claim and desire to secure by Letters Patent is:

1. In a fan structure of the character described, a driving element, a cowling engaged with the driving element, spokes of stressed skin structure radiating from the driving element and terminating at the periphery of the cowling, reinforcing stringers on the compression sides of the spokes,

rant-blades arranged exteriorly of the cowling, and means connecting said blades and spokes.

2. In a fan structure of the character described, a driving element, a cowling engaged with the driving element, spokes of stressed skin; structure radiating from the driving element and terminating at the periphery of the cowling, reinforcing stringersontheinner and outer surfaces of the compression sides of the spokes, fan blades arranged exteriorly of the cowling, and means connecting said blades and spokes.

3. In a fan structure of the character described, a driving element, a cowling engaged with the driving element, spokes radiating from the driving element and terminating at the periphery of the cowling, fan blades of stressed skin structure connected with the spokes exteriorly of the cowling, longitudinally arranged reinforcing stringers mounted in said blades on opposite inner surfaces thereof, and longitudinally spaced transversely arranged plates connecting and bracing said stringers.

4. In a fan structure of the character described, a driving element, a cowling engaged with the driving element, .at least one spoke member arranged within the cowling and connected with the driving element, a connecting member at the outer end of the spoke, at least one fan blade arranged exteriorly of the cowling, a connecting member at the inner'end of the fan blade engageable with the connecting member of the spoke, said fan blade having a well, and means joining said connecting members of the spoke and fan blade having a portion exposed in said well to allow manipulation thereof exteriorly of thecowling for effecting assembly and disassembly of the spoke and blade relative to each other without disassembly of said cowling.

5. In a fan structure of the character described, a driving element, a cowling engaged with the driving element, spokes radiating from the driving element and terminating at the periphery of the cowling, blades arranged exteriorly of the cowling and connected with the spokes, and compressible sealing means arranged between the blades and cowling.

6. In a fan structure of the character described, a driving element, a hub keyed to the driving element, a cowling engaged with the hub, at least one spoke member distressed skin structure arranged within the cowling and secured thereto, at least one fan blade of stressed skin structure arranged exteriorly of the cowling, said fan blade having a well, and means connecting the spoke and fan blade having a portion exposed in said well to allow manipulation thereof for effecting assembly, disassembly and adjustment of the spoke and blade relative to each other without disassembly of saidcowling.

7. In a fan structure of the character described, a driving element, a hub keyedto the driving element, a cowling engaged with the hub, at least one spoke member of stressed skin structure arranged within the cowling and secured thereto, at least one fan blade of'stressed skin structure arranged exteriorly of the cowling, said fan blade having a well, a housing arranged about the path of the outer end of said blade, and means connecting the spoke and fan blade having a portion exposed in said well to allow manipulation thereof for efiecting assembly, disassembly and adjustment of the spoke and blade relative to each other without disassembly of said cowling and housing.

8. In a fan structure of the character described, a driving element, a cowling engaged with the driving element and having openings in the periphery thereof, spokes of stressed skin structure radiating from the driving element and terminating at the periphery of the cowling and in alignment with the openings therein, a connecting member at the outer end of each spoke having a portion extending through said cowling opening, a fan blade having a connecting member thereon, and means engaging the fan blade connecting member exteriorly of the cowling for connecting and mounting the fan blade on th connecting member of the spoke.

ROBERT D. MOORE.

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