US2324759A - Wind wheel and blade therefor - Google Patents

Description

J y 1943. B. BRASSELL 2,324,759 WINDWHEEL A ND BLADES THEREFOR Filed March 4. 1941 Patented July 20, 1943 UNITED STATES PATENT OFFICE WIND WHEEL AND BLADE THEREFOR Bryan Brassell, Puerto de Luna, N. Mex. Application March 4, 1941, Serial No. 381,741

10'Claims. (01470- 79) l The present invention relates to improvements in windwhecls and. blades therefor.

, The primary object of the invention is to provide a windwheel having novelly constructed blades which will operate more eificiently and will present an increased area to the wind velocity.-

A further object of the invention is to provide a windwheel blade of the above-mentioned type having wind velocity escape openings at spaced intervals to further increase the efiiciency of the windwheel and the rotary power derived therefrom. 1

. A still further object of the invention is to provide a windwheel of the aboveementioned character in which the blades are braced by means of truss rods extending longitudinall of the blades and diagonally thereof.

Other objects and advantages of the invention will become apparent during the course of the following description of the accompanying drawing, wherein,

Figure 1 is a front elevational view illustrating the manner in which the blades are secured to the windwheel frame and showing the general arrangement thereof;

Figure 2 is a detail side elevational view showing the ribbed portions of the blade: extending transversely of the length thereof and also showing the position of the brace bars and connecting struts;

Figure 3 is a transverse cross-sectional view, taken on line 33 of Figure 1, looking in the direction of the arrows, illustrating in detail the punched out openings for allowing the escape of a portion of the wind velocity; and

Figure 4 is a perspective view, showing a modi fied form of the invention.

In the drawing, wherein for the purpose of illustrating the invention and wherein like reference characters will be employed to designate like parts throughout the same, the reference character 5 will generally designate the hub of a windwheel having radially directed spokes 6 connecting an annular band 1 and extending outwardly as at 8 to a circular rim 9 which is adapted to connect the free ends of the spoke extensions 8.

Mounted on the annular band I at spaced intervals and extending outwardly therefrom in a radial direction is a series of windwheel blades which will generally be designated by the referonce character it) and said blades are mounted obliquely with respect to the annular band 1 so that the windwheel Will be rotated when presented to the wind velocity.

The blades (Figs. 1 to 3) are formed of sheet metal, and stamped into a particular configuration-the blank having somewhat of the appearance of a truncated taper before shaping, 3 with the larger end possibly curved slightly; as indicated. The shaping of the blade is such as to provide a succession of spaced-apart transverselyextending surfaces of materially less widththan the spacing between such surfaces, the surfaces presenting the ap earance of transverse bands of substantially uniform Width, with the innermost band spaced some distance from the smaller end of the blank. The spaces between adjacent bands is formed concave, with the concavity extending. from such adjacent bands; the outer band is also located spaced from the larger end of the blank, and this space is also concave, with the concavity leading from the outer band to the end of the blank. Since the bands have their directions of length extending transversely of the blank, it is apparent that the bottoms of the concavities also extend in such transverse direction; the space between the innermost band and the smaller end of the blank is retained substantially fiat excepting for the curvature leading to the inner band -this latter portion is indicated at H, with the blade generally indicated at H). The inner band i indicated at 12, with the remaining bands indicated at I5.

The bands l2, I5, may be curved in the direction of a radius of the blade, to set up a somewhat undulatory appearance to the shaped blade, but, because of the particular arrangement of Fig. 3, the bands tend to closely approach flatness, since this offers the simplest way in which to provide the bent tonguesindicated at IT, these being formed by providing a semi-circular punching at one side of lines each corresponding approximately to a radius of the blade, each of such lines constituting a bending line for the material within the semi-circular bounds of the punched opening, the material being carried rearwardly at an angle to the plane of the band, as indicated in Fig. 3, thus leaving the band itself presenting a more or less planar face provided with a plurality of preferably uniformly-spaced openings l6 provided by the punching action, with the punched portions or tongues l'l extending rearwardly of such planar face. As indicated by Figs. 1 and 3, the tongue I! extend in the direction of the leading edgev of the blade. Since the blade itself extends angular to its path of rotation, this arrangement of the tongues places each of them as a barrier in the path of air passing through openings l6, and at the same time tends to direct such passing air in the direction of the leading edge of the blade.

Aside from the tongues H, the stamped blade presents the effect of top and bottom planes spaced apart a distance sufficient to give material depth to the concave portions indicated at l3the inner concaveand 14 indicating the remaining concaves; Fig. 2 illustrates the depth, in this respect, the View indicating that the bands I2, I5each of which may be considered as a perforated zone of the blade-are located on what may be considered as the top plane of the per forated zonewhile portion l I and the bottom of the concavities l3, l4, extend on a common plane which may be considered as the bottom plane of the concave zones-each concavity being considered a a concave zone. Sinc the blade is set at an angle to the path of rotation, it will be apparent that the leading edge of the blade will present an irregular contour in the air-flow path to the blade, due to the fact that the angularity of the setting tends to present the third dimension of depth as represented by the top and bottom planes referred to.

Because of the bending actions required in stamping the blank into the form indicated, it is apparent that While the Width of the blade is strengthened by the presence of the perforated and concave zones, the fact that the direction of length of all bending linesexcepting those for tongues |1-is transverse of the blade, tends to Weaken the resistance of the blade considered in the direction of length of a radius of the wheel extending through the blade; the bending lines of the tongues will tend to sustain the bands or perforated zones, while the concave form of each of the concave zones tends to resist bending of these zones, but the bendin line at the juncture of a concave zone and a perforated zone presents little additional support against bending under excessive wind pressures, especially where the blades are of considerable lengtha reason why blades employing concavities extending transversely of the blade have not generally been utilized commercially. T avoid this weakness and to avoid the need for using heavier metal thickness to the blades-and which would add materially to the weight of the windwheelI have provided a brace formation, which will now be described.

Along each edge of the blades l and extending parallel therewith are longitudinal brace rods l8 which have their outer ends connected to the tip of the blade by welding or the like and the contacting portions of the ribs 12 and I may likewise be welded to the rods l8.

Similarly, the rear face of each blade I0 is provided along its longitudinal edges with brace rods l9 and the outer end of each brace rod is connected as at 20 to the curved portion I 4 of the blade and the contacting portions I3 and 14 extending inwardly from the Outer end of the blade are also Welded to the brace rod I9. The extreme inner end 2| of each brace rod I9 is held in place by being welded to the substantially flat portion ll formed on the inner end of the blade.

Diagonal truss bars 22 are connected to the brace rod l8 and I9 and it is to be noted that the truss bars 22 extend through openings 23 adjacent the longitudinal edges of the blades within the curved portions thereof.

Each blade s held in position by the rim 9 extending through an opening 24 formed in the intermediate curved portion M as is clearly shown in Fig. 1.

A modified form of the invention is shown in Fig. 4, in which the blade is shown with but one perforated zone and one concave zone, the former being indicated at l5a, with the concave zone indicated at Ma; in other words, this form omits all but the outer concave zone and. perforated zone of Fig. 1, the inner end I la being lengthened accordingly. The openings [6a and tongues Ila are similar to the openings and tongues of Fig. 3.

A number of particular advantages accrue through the use of the blade thus described in detail, amongst which are to be found the fo1 lowing:

As is well-known, the blade which utilizes one or more transversely-extending concave zones provides greater efiiciency than other forms of blades in windwheel service, due mainly to the fact that there is less resistance present and thereby renders the air particle action to be more efiective in developing the power of the wheel. However, such structures have certain weaknesses due to the fact that to provide the transverselyextending concavities, the bends which produce the concavities also extend transversely of the blade and therefore offer littl or no resistance to bending of the radial blades under the action of strong air-currents, especially where the blades are of considerable radial length; to avoid this condition heavier stock could be used, but this substitution tends to unduly increase the Weight of the wheel. As a result, other forms of blades have been preferred in commercial usage, as, for instance, blades which are partially concaved radially, the curvature thus corresponding generally to the direction of length of the blade and therefore offering a resistance to bending without adding materially to the weight; such structures are generally considered as providing approximately 38% efficiency, and of sufficient lightness as to make their usage possible, especially under the larger diameter Wheel conditions.

With a view to meeting this condition, the present invention, in utilizing the transverse curvature length, accompanies it by a strengthening in the direction of blade length. The concave portion or portions are made of suilicient depth as to provide a material distance between opposite face planes, and this distance is bridged by bracing structures-the rods I0 and I3 and the diagonals 22-such as to give rigidity with a minimum addition of Weight, thus tending to produce a truss effect between the opposite face planes and thereby decrease the tendency of the blade to bend under wind pressures. In addition, the bent portion or portions located at the nearer edge zones of the concavities, are formed to increase the resistance against bendingthe structures H provided in forming the transverselyalined openings 16; as will be noted from Fig. 3, the structures take the form of tongues I7, bent inward at an angle to the plane of the zone, the bending being on a straight line which thus corresponds to the direction of length of the blade, and therefore perpendicular to the line of bend which is provided by the side edge zone or zones of the concavities; the transverse succession of such bends therefore tends to stiffen the portion of the blade which must resist the bending stresses of the wind pressure.

Hence, the blade is strengthened against such stresses through the truss-like effect set up between opposite faceplanes, and by the presence of the transverse succession of bends of tongues H. While the presence of the tongues could imply a resistance effect on the advance of the blade, the blade, in operation tends to set up an opposite effect from this-as presently described-so that the efficiency of the blade is not impaired and will have the advantages of the transverse concave length and without materially increasing the weight; a lighter stock may. in

factbe used, since the bracing structures provide increased rigidity, so that the increased efficiency can be secured without increasing the the vane throughout the period of contact, and

the velocity of the stream relative to the vane must be constant throughout this period, it being understood that the direction of the wind is parallel with the wheel axis, and that the blades are set at an angle to the plane of rotation, the air stream thus flowing rearwardly across the blade surface. As a result, the effective pressure of the air is more or less limited. In practice, the calculations place the air stream a leaving the trailing edge and continuing onward and reaching the path of the succeeding blade, so that the paths of these practically determine the width of the air stream that can satisfy the rule, and this width is considered as the effective pressure; the amount of air delivered to the vane isconsiderably in excess of the volume within the stream, and the excess must be taken care of by passing outward from the blade other than over'the trailing edge-generally moving outward over the peripheral edge of the blade. In other words, only a percentage of the air is actually made active in driving the wheel, the remainder being required to be discharged from the blade path, and by offering the least possible resistance to the advance of the blade; the air friction, set up by the radial travel of the excess air and made manifest on the rear face of the vane itself, offers a material resistance effect to the vane advance.

In the present invention, this condition is largely overcome through the presence of the transverse series of openings l6 which permit the air to escape at once to the rear of the blade so that the excess volume to be taken care of is greatly reduced. The concave active portions can carry a greater depth of air-streamthe depth: controls the effective value of the wind pressure-thus not materially reducing the power although the power is being provided in spaced zones rather than in a continuous zone. The

blades are set at approximately 40 to the blade .carries a large number of blades so that the succession brings the trailing blade into the zone of the discharged air stream of thepreceding blade quicklythe conditions that are usually present with the commercial forms of wheels. In the latter, the side edges of the blades are generally straight radially of the wheel, so that the leading edge is made active concurrently throughout it length, the air-stream forming and passing off the trailing edge concurrently throughout the length of the blade. The wind thus brings the air particles into contact with the blade at an angle to the blade and thus develops the air stream characteristics, with the excess air travelling radially of the rear face of the blade in its escape. With a large number of vanes the spacing between them is comparatively small, so that the tendency of the discharging air-stream is to reach into the zone of the oncoming blade before dissipation; where this occurs, the conditions of an advancing rear face of a vane faces the conditions of an actually retiring air stream, thusincreasing the frictional effect over that which would be present while travelling in still air, since a larger amount of air is brought into contact per unit of time. The rear face of a vane thus is caused to be bathed first with the radially-flowing air stream provided by the excess air of the vane, and then by the retiring air-stream from the previous vane, with the two moving in directions angular to each other, and both setting up air-friction conditions.

In the present invention, with its deep transverse concave length and the juncture zone of adjacent concaves considerably in advance, it is understood that the leading edge doe not present a straight line to the wind direction but rather a shaped line, with the major portionof the active blade portion curved in forming the concave zone or zones. Hence, the interception of the approaching air-particles is not along a straight line (as in the commercial forms) but rather along curved lines, as is the discharge from the concave zone or zones; as a result, a view of the wheel in the direction of its axis presents the space between vanes as of irregular side margins, as compared with th straight margins of the-commercial forms. Since the air interception by the vane interrupts the normal flow of the wind-driven air-particles, the condi tions in rear of the vane are ailected, and it is the latter condition that tends to control the airfriction conditions.

In the commercial types, as above pointed out, there is presenta condition of continuous counterflow over the rear face of the vane-a part of the flow being radial and the remainder transverse. With the present invention there is a variation in this respect, due to the fact that openings I! provide for air-flow through the vane to the rear side of the vane so that this portion the delivered air is discharged from the vane in rear of the air stream which passes from the concave and is thus ineffective to create airfriction on the succeeding blade, thus reducing the frictionto this extent.

However, an additional effect is set up through the presence of the transverse series of openings I6. As indicated in Fig. 3, the bent tong I! are located in rear of the openings, but extend in the direction of advance of the vane in service atlan angle to the plane of rotation of the vane as well as inclined to the transverse direction of the vane. Hence, the air particles can pass through the openings to the rear of the vane Where they impinge the tongues l '1 and then flow in a forward directionthe same general direction in which the wheel is advancing; this airflow through the openings tends to prevent the tongues offering a resistance to the advance of the Wheel, due to the fact that the air-flow through the openings prevents the air in rear from attempting to enter the path of travel of the tongues. The tongues are of similar dimensions, so that the inclination of the vane itself places the tongue zone as of uniform depth so that there is presented a constant tendency to shield the tongues against developing active resistance. And since this air-flow through the openings is to the rear of the vane and therefore into the zone in which the general air-flow has been intercepted by the vane itself, the air being discharged through the openings tends to overcome any possibility of material pressure reduction in rear of the vane, as well as rapidly commingling with the surrounding air, so that, in the zone of the openings, the rear of the blade is subject only to the friction of comparatively still air.

While the discharge from the preceding vane concave tends to provide an air-stream effect on the rear of the concave of the succeeding vane, this delivery of air through openings I6 tends to spread along the curved surface and thus tends to form a layer effect between the stream and the rear face and tend to force the stream rearward and thus less effective in creating air-friction with such face.

As will be seen the tongues I! are simply portions of the material of the perforated zone of the blade, each opening formed being arcuate at one side and straight at the other, the straight side providing the bend while the arcuate side is forced rearwardly by dies during the formation of the blade, but without removal of the material of the opening from the bladethe latter material forms the tongues I1, and these extend in rear of the openings and form air bafiles for directing the air passin through the openings.

It is to be understood that the forms of the invention herewith shown and described are to be taken as the preferred embodiments thereof and that various changes in the shape, size and arrangement of parts may be resorted to without departing from the spirit of the invention or the scope of the subjoined claims.

I claim:

1. In windwheel structures, wherein the blades extend radially of the wheel and the width of the blade is located angularly to the rotation path of the wheel, a sheet metal blade formation including a pair of adjacent zonal surfaces having their respective directions of length extending in general parallelism and transversely to the radial blade length of the wheel, one of said zonal surfaces being concave in cross-section of it length dimension with the concave facing the direction of approaching air flow to the wheel, the other of said zonal surfaces having a succession of generally-similar perforations or openings with the succession extending in the direction of length of the zone and with each perforation or opening having a bent wall extending rearwardly of the perforation or opening, the wall bend extending in the direction of the radial blade length of the wheel, the bottom of the concave zonal surface and the top of the perforated zonal surface of a blade extending in substantially parallel planes spaced apart a material distance to thereby provide a material depth to the concavity of the concave zonal surface, bracing rods extending radially of the blade in such planes, and diagonally-extending bracing members extending between such planes and connected to the bracing rods of both planes, said bracing rods and bracing members with the bent walls serving to brace the blade against blade buckling under wind pressure during service.

2. A blade as in claim 1 characterized in that the bent wall of a perforation or opening has a configuration corresponding to the configuration of the perforation or opening.

3. A blade as in claim 1 characterized in that the bent wall of a perforation or opening has a configuration corresponding to the configuration of the perforation or opening and extends angularly to the plane of the perforated zonal surface to form an air baffle in rear of the perforation or opening.

4. A blade as in claim 1 characterized in that the bent wall of a perforation or opening extends angularly to the plane of the perforated zonal surface and extends in the direction of advance of the blade in service.

5. A blade as in claim 1 characterized in that the concave zonal surface is located more remote from the axis of rotation than the perforated zonal surface.

6. A blade as in claim 1 characterized in that the blade includes a succession of parallel groups of concave and perforated zonal surfaces with the concave zonal surface of a group more re-' mote from the axis of rotation than the perforated zonal surface.

'7. In windwheel structures, wherein the blades extend radially of the wheel and the width of the blade is located angularly to the rotation path of the wheel, a sheet metal blade formation including a pair of adjacent zonal surfaces havin their respective directions of length extending in general parallelism and transversely to the radial blade length of the wheel, one of said zonal surfaces being concave in cross-section of its length dimension with the concave facing the direction of approaching air flow to the wheel, the other of said zonal surfaces being located at the top plane of the concave zonal surface and forming a continuation of one side of the latter zonal surface to thereby provide a group of the two zonal surfaces, said perforated zonal surface hav-" ing a succession of generally-similar perforations or openings with the succession extending in the direction of length of the zonal surface and with each perforation or opening having a bent wall extending rearwardly of the perforation or opening, the wall bend extending in the direction of the radial blade length of the wheel, the bent wall leadin angularly to the plane of the zonal surface and in the direction of advance of the' the concave zonal surface of the group lies moreremote from the axis of rotation of the wheel than does the perforated zonal surface of the group.

10. A blade as in claim 7 characterized in that the radial length of the blade includes a succession of groups of concave and perforated zonal surfaces, with one group imrnediately adjacent another group, and with the concave zonal surface of a group more remote from the axis of rotation of the wheel than the perforated zonal surface of that group.

BRYAN BRASSELL.

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