US 3294175 A
Description (OCR text may contain errors)
Dec. 27, 1966 'c. H. BODNER 3,294,175
ADJUSTABLE IMPELLER Filed Oct. 11. 1965 IMAM/roe. C/MEL ES hf 6004/52 United States Patent 3,294,175 ADJUSTABLE IMPELLER Charles H. Bodner, 2413 127th Ave. NE., Bellevue, Wash. 98004 Filed Oct. 11, 1965, Ser. No. 494,426 2 Claims. (Cl. 170160.61)
The present invention relates to impellers or fan devices; more particularly, the invention relates to impellers or fans which direct impelled fluid in a converging beam for spot blowing.
In conventional impellers or fans, a centrifugal as well as forward motion is given to the fluid by rotation of the blades. Substantial amounts of air are therefore lost at the blade tips and the pattern of air flow is a diverging or spreading one, wherein the concentration of air flow diminishes as the area of the stream increases. Tip losses represent losses in efiiciency and of power. Moreover, noises are produced by the blade tips.
The present invention provides a plurality of arcuate vanes extending forwardly from each blade of the impeller. The vanes have respective centers of curvature which are spacedapart in a direction which is radial of the rotation axis of the impeller assembly, and which is disposed at a substantial angle relative to the pitch axis of the blade. The inner vanes on each blade are therefore eccentric with respect to the rotation axis, and their trailing edges are spaced apart farther than their leading edges, with the trailing edges of respective inner vanes being nearer the rotation axis than their respective leading edges. Therefore, fluid being impelled in the forward direction by the rotating impeller assembly is urged radially inwardly by centripetal action of the vanes to converge the fluid stream being impelled in the forward direction.
An important feature of the invention is that the fluid is directed in a converging beam to make it possible to direct a converging stream of fluid to a small area for greatly improved efiiciency of utilization of the fluid. Thus, in an air impeller, relatively noiseless spot blowing of air is possible. This obviously has many applications, as for example, in the cooling of motion picture projectors, where a cooling fan producing maximum directed air flow and a minimum of sound is desirable.
It is also an important feature of the present invention that it provides means for varying the focal point or area of the converging beam of fluid so that the distance for most effective fluid concentration or spot blowing may be varied as desired.
It is, therefore, an object of the present invention to provide fan or impeller means adapted to provide a converging stream of impelled fluid for concentrating the effect of such fluid, thereby improving the effectiveness of such fan or impeller means.
An object of the invention is the provision of impeller means according to the foregoing object, wherein radially spaced arcuate vanes extend forwardly from blades of the impeller and are eccentric relative to the rotation axis of the impeller assembly, thereby imparting radial inward motion to fluid impelled forwardly by the impeller assembly to converge the fluid stream being impelled in the forward direction.
An object of the invention is to provide novel fan or impeller means which are adapted to produce a converging beam of fluid and wherein the distance of the point of convergence from the fan or impeller means may be varied.
Still another object of the present invention is to provide fan or impeller means wherein the impeller blades are capable of eliminating tip losses whereby to increase efliciency and decrease sound production.
A further object of the present invention is to provide novel fan or impeller blade constructions wherein the loss 'ice of fluid moving centrifugally outwardly from the tips of such conventional blades is prevented, thus obviating losses in efficiency and undesirable noise production factors.
Other objects, features and advantages of the present invention will become apparent to those versed in the art from a consideration of the following description, the appended claims and the accompanying drawings, wherein:
FIGURE 1 is a front elevational view of an impeller construction illustrative of the principles of the present invention;
FIGURE 2 is a schematic view, in reduced scale, indicating the nature of converging beams of fluid flow which may be effected by the impeller of FIGURE 1;
FIGURE 3 is an enlarged cross-sectional view, taken along the lines 33 of FIGURE 1, but showing the blade element in elevation for clarity of illustration;
FIGURE 4 is an enlarged fragmentary cross-sectional view, taken along the lines 4-4 of FIGURE 3, illustrating a detail of the pitch changing mechanism of the impeller;
FIGURES 5 and 6 are schematic views taken generally along the lines 5-5 of FIGURE 3, showing the positioning of elements of the pitch changing mechanism in two different positions of adjustment;
FIGURE 7 is an exploded view of the hub components of the impeller assembly of FIGURE 1 showing only one impeller blade, for simplicity of illustration; and
FIGURE 8 is a schematic showing of a top view of an impeller blade, locking toward the hub thereof, showing various positions of pitch adjustment of the blade.
Referring to the drawings, and particularly to FIGURE 1, there is illustrated an exemplary embodiment of the present invention. An impeller assembly comprises a hub assembly designated by the reference numeral 20 and three blades generally designated 22, secured in said hub assembly.
As shown in FIGURE 1, each of the blades 22 has a broad configuration with substantially parallel side edges without taper and having a curved outer edge portion extending across the width of the blade.
Extending forwardly from the forward or impelling space of each blade 22 are arcuate vanes '26, 28 and 30. Vane 26 is adjacent to the outer or peripheral curved edge of the blade. As indicated in FIGURE 1, vane 26 is curved about rotation axis C of the impeller assembly, and has a radius of curvature R Inner vanes 28, 30 have their respective centers of curvature C C spaced apart ina direction or along a line extending radially from the rotation axis C and at right angles to the pitch axis P of the blade, the pitch axis extending from rotation axis C radially outward parallel to the blade edges. As shown in FIGURE 1, the trailing edges of the vanes are therefore spaced farther apart than their leading edges, and the trailing edges of the iuner vanes are closer to rotation axis C than their respective lea-ding edges.
As is common in this art, the impeller blades may vary in pitch from the hub end or root to the tip end, such pitch variation being effective to more effectively direct the air forwardly. In the illustrated example, it is desirable that the pitch of the blade (in its neutral position) vary from about degrees at its root to about degrees at its tip.
A feature of the present invention is that the blades are mounted in such a manner that their pitch may be varied. It is considered best to describe the blade configuration and the eflect of pitch variation at this point, without regard to specific pitch adjustment means, in order that the general purposes and principles of the present invention may be more easily understood. A specific example of one mounting and pitch changing assembly is described hereinafter.
In operation, the impeller assembly is rotated clockwise, as viewed in FIGURE 1 to impell a fluid stream in the forward direction, which direction is outward as viewed in FIGURE 1, and rightward as viewed in FIGURE 2.
From the foregoing description and from the drawing, it will be understood that the eccentric arrangement of the vanes and the above-described relative spacing of the trailing edges of the vanes, fluid is discharged or impelled from the trailing edges of the respective blades 22 with a radially inwardly directed component of motion. The fluid stream being impelled in the forward direction because of the pitch angle of the blade is urge-d radially inwardly by centripetal action of the vanes, thereby effecting convergence of the impelled fluid stream, as indicated in FIGURE 2. As hereinafter described, the degree of convergence or point of convergence is controlled by selective variation of the pitch angle of the blades 22.
Each blade has a greater area or length on one side of its pitch axis than on the other side, as may be best seen in FIGURES 1 and 8, so that when the pitch is changed by rotating the blade about its axis, the relative positional placement of each vane on the blade is altered. FIGURE 8 illustrates a top view of the blade at various different pitch angles, and FIGURE 2 illustrates the nature of the directed convergent fluid stream as impelled by a blade assembly in corresponding blade adjustment positions.
In the solid line position of FIGURE 8, the blade is in a neutral central position, having normal pitch as previously discussed, this position being that shown in FIGURES 1 and 3, and schematically in FIGURE 5. This neutral blade pitch angle produces a fluid stream pattern as shown in full lines in FIGURE 2. If the pitch of the blades is increased to the dotted line position of FIGURE 8, the fluid stream pattern is caused to converge to a point or area closer to the impeller assembly, as shown in dotted lines in FIGURE 2.
Conversely, if the blades are each rotated to a lesser pitch as shown in dot-dash lines in FIGURE 8, the fluid stream pattern is caused to diverge from the neutral pattern so that concentration of the stream is at a point more remote from the impeller assembly, as shown in dotdash lines in FIGURE 2.
Comparison of the vane positions illustrates that variation of the pitch of the blade causes a change in the relative angle of the tangent to the trailing edges of the vanes 26, 27, 28 so that the directional forces imparted to the fluid stream leaving the vanes is varied thereby, as previously described.
Thus it may be seen that impeller blade assemblies of the above described construction are adapted to focus converging streams of fluid to a relatively small area and, by variation of the pitch, to vary the distance of such area from the blade assembly. It is considered that many types of blade mounting and pitch varying means might be utilized and the drawings herein illustrate one example of such means.
Reference is now made specifically to FIGURES 1, 3, 4 and 7 of the drawings, which illustrate an exemplary blade mounting and pitch varying means which can be used to form an impeller assembly according to this invention.
As shown in FIGURE 3, each of the impeller blades 22 has an integral cylindrical portion at its root end and an enlarged base flange 34 integral with the collar at its inner end forming a shoulder to engage retaining bushings 38 and 40.
Base flange 34 in each case, has a radially outwardly extending portion having a downwardly extending crank pin 36.
The hub assembly for holding the plurality of blades (three in the illustrated example) comprises a front retaining bushing 38, a back retaining bushing 40, an inter- 4 nal cam element 42 and an adjusting nut element 44, as best shown, disassemble-d, in FIGURE 7.
Retaining bushings 38 and 40 are generally circular members having mating inner faces 46. Each of the faces 46 has a number of semi-cylindrical cut-outs 48 therein. Cut-outs 48 are equi-angularly spaced on the faces 46 and equal in number to the number of blades in the assembly. In the assembled relationship of bushings 38 and 40, mating cut-outs 48 provide bearings for the cylindrical portions of blades 22, as best seen in FIGURE 3. Bushings 38 and 40 are flat on their internal surfaces along the lengths of the bushings, as at 50, in the areas of cutouts 48 to provide flat shoulders for engagement of the shoulders of the base flanges 34 of the blades 22. Bushings 38 and 40 have appropriate bores 52 for reception of means (not shown) for securing the bushings together. Front bushing 38 has a forward extension 54 having a circular bore 56 therethrough for reception of drive shaft means (not shown).
The internal cam element 42 is of generally hollow construction, having a through bore 58 of similar diameter to that of bore 56 of the front bushing element. The external surface of cam element 42 comprises a forwardly disposed enlarged portion of angular surfaces, as at 59, and a reduced cylindrical portion 62. The enlarged portion 59 has a plurality of flat surfaces 60 adapted to engage the inner flat surfaces of the base flanges 30 of the blades 22 whereby the blades are clamped securely against radial movement, between surfaces 60 and 50 of the cam element and of the retaining bushings, respectively. The smaller cylindrical portion 62 of camelement 42 is externally screw-threaded, as best shown in FIGURES 3 and 7, and the periphery of said portion 62 is provided with cam grooves 64 extending at similar angles to the longitudinal axis of the cam element, such grooves being equal in number to the number of flats 60 and generally aligned therewith so that the crank pin 36 of each of the blades 22 extend into a groove 64 when the parts are assembled.
Assembly is effected by insertion of the cam element and the blade flanges internally of the front and rear retainer bushings, with the cylindrical portions of the blades retained in the bearings formed by the mating cut-outs 48, with the base flange 34 of each blade retained between the surfaces 50 and 60, and with the crank pin 36 of each of the blades retained in a cam groove 64. The front and rear retainer bushings are secured together, in face to face relationship, by fastening means (not shown) extending through the bores 52. It should be noted, in the assembly thus far described, that the cam element 42 is not free to rotate relative to the retaining bushing elements 38 and 40 by virtue of the angular configurations of these parts, but has freedom for longitudinal movement.
The adjusting nut 44 is then applied to complete the assembly and to provide means for varying and controlling the pitch of the blades 22. Adjusting nut 44 is a generally annular piece having internal screw threads, as at 66, of a size to engage the external threads of the portion 62 of the cam element 42 and the assembly is completed by threading these two pieces together. Obviously, with the adjusting nut against the flat rear face of the back retaining bushing 40, movement of the nut in either rotational direction is effective to cause cam element 42 to move longitudinally, since the cam element is restrained against relative rotational movement for reasons previously mentioned. Such longitudinal motion of the cam element is effective to cause the crank pins 36 of the impeller blades to be simultaneously and equally shifted angularly relative to the axes ofthe blades due to longitudinal movement of the grooves 64, which imparts lateral movement to the crank pins. Fastening means, not shown, are provided to hold the nut 44 against the rear face of the back retaining bushing 40 and to lock the nut in any position of adjustment.
FIGURE 5 illustrates schematically the neutral position of a blade, and FIGURE 6 illustrates the increased pitch position of a blade, these figures illustrating the movement of cam grooves 64 and the relative movement of the crank pins therein.
From the above, it may be seen that the present invention provides impeller constructions which are capable of increased efliciency of fluid propulsion with decreased noise effects and wherein the fluid may be selectively directed in a convergent stream to a focal point or area which is a varying distance from the impeller.
Although a specific embodiment of the present invention has been described and illustrated in detail, it is to be clearly understood that the same is by way of illustration and example only; it is to be understood that the invention is not limited thereto, as many variations will be readily apparent to those versed in the art and the invention is to be given its broadest possible interpretation within the terms of the appended claims.
The inventor claims:
1. An impeller assembly rotatable about a rotation axis to provide a converging fluid stream in a forward direction, said impeller assembly comprising means for rotating the assembly, a plurality of blades extending radially outward from said rotation axis, each of said blades being inclined at a pitch angle about its pitch axis to impart forward thrust to surrounding fluid, a plurality of radially spaced arcuate vanes extending forwardly from the forward face of each of said blades, each of said blades having a larger area on the trailing side of its pitch axis than on the leading side thereof, said respective inner vanes having progressively shorter respective radii of curvature in the radially inward direction, the outer vane being adjacent to the periphery of the blade and being curved, said vanes on each blade having respective centers of curvature spaced apart in a direction radially of the rotation axis and at a substantial angle relative to the pitch axis of the blade, whereby the trailing edges of the vanes are spaced apart farther than their leading edges and the trailing edges of respective inner vanes are nearer the rotation axis than their leading edges, whereby fluid is discharged from the trailing edges of the blades with a radially inwardly directed component of motion, whereby fluid is urged radially inwardly by centripetal action of the vanes to converge the fluid stream being impelled in the forward direction, and mechanical means for coordinate variation of the pitch angle of the blades to provide compound curvatures of respective vanes according to the selected degree of convergence and the selected distance from the blades of the focus of said stream of impelled fluid.
2. An impeller assembly rotatable about a rotation axis to provide a converging fluid stream in a forward direction, said impeller assembly comprising means for rotating the assembly, a plurality of blades extending radially outward from said rotation axis, each of said blades being inclined at a pitch angle about its pitch axis to impart forward thrust to surrounding fluid, a plurality of radially spaced arcuate vanes extending forwardly from the forward face of each of said blades, each of said blades having a larger area on the trailing side of its pitch axis than on the leading side thereof, said respective inner vanes having progressively shorter respective radii of curvature in the radially inward direction, the outer vane being adjacent to the periphery of the blade, said vanes having respective curvatures such that their trailing edges are spaced apart farther than their leading edges and such that the inner vanes are eccentric relative to the rotation axis and have their trailing edges positioned nearer the rotation axis than their respective leading edges, whereby fluid is released from the trailing edge of each blade with a radially inwardly directed motion component to converge the fluid stream being impelled in the forward direction, and mechanical means for coordinate variation of the pitch angle of said blades to provide compound curvatures of respective vanes according to the selected degree of convergence and the selected distance from the blades of the focus of said stream of impelled fluid.
References Cited by the Examiner UNITED STATES PATENTS 813,074 2/1906 Barber. 2,359,466 10/1944 Currie 170170 2,498,170 2/1950 Meier 170170 2,574,951 11/ 1951 Benson. 2,763,329 9/1956 Feroy l-160.47
FOREIGN PATENTS 426,729 5/ 1911 France.
9,930 1891 Great Britain. 14,684 1899 Great Britain. 17,935 1910 Great Britain. 19,354 1911 Great Britain. 3,222 1915 Great Britain.
MARTIN P. SCHWADRON, Primary Examiner.
SAMUEL LEVINE, Examiner.
E. A. POWELL, JR., Assistant Examiner.