US2317502A - Propeller type ventilator fan - Google Patents

Description

April 27, 1943.

W. L. UPSON PROPELLER TYPE VENTILATOR FAN Filed June2l, 1940 1 FIGS.

-INVENTOR. WALTER L.UPSON BY M ATTW Patented Apr. 27, 1943 UNITED STATE PROPELLER TYPE vENTmA roit FAN Walter L. Upson, Litchfleld, Conn., assignorto, The Torrington Manufacturing C0,, Torrington, Conn., a corporation of Connecticut I t Application June 21, 1940, S erialNto. 34.1,659-

12 Claims. (Cl.v170 159) V This invention relates to improvements in propeller type ventilator fans, and more particularly to fans of the larger sizes, such as used for the ventilation of residences and other buildings. More specifically, the present improvements pertain to balancing and silencing features which are particularly applicable to fans of the noted types.

Two methods have been generally heretofore utilized in balancing theblade structure of propeller type fans; the first of these consists in removing a certain amount of the mass from one or more of the-blades, as by grinding or the like, while the second method is usually practiced by displacement of one or several of the blades of the fan, to the end of altering the relation be,- tween adjacent blades in the plane of rotation, with the efiect of varying the distribution of the weight of the blades about the axis of revolution of the fan. It is obvious that neither of these methods is fully satisfactory, in that a condition of true balance is often only approximated. For example, if too great an amount of metal is removed as by grindingincident to balancing, the blade area and shape are adversely affected. Similarly with respect to the method involving the bending of the blade or the supporting arm therefor, if the fan is verygreatly out of balance this method can only approximate a. full correction of the condition of unbalance. Each of the noted methods of balancing is timeconsuming and expensive, and is not susceptible of any quantitative method of predetermining the extent of correction required in order fully to balance the fan. 3

It will be obvious that neither of the methods heretofore usually practiced is adaptable to most types of ventilator fans, which are usually'constructed in the larger sizes, for example, in diameters of 24", 36" or even greater diameters...

It is accordingly a major object of the invention to attain an improved method and structure for balancing fans of types in which the blade-carrying arms and blades are formed of more than the usual gauges of sheet metal, and which may be quickly and easily utilized in the balancing of fans without any appreciable deflection, distortion, grinding or other removal of metal of the blade.

Yet another object of the invention is attained in an improved means for reducing the noise transmitted by propeller type fans, which means is, or may be practiced incidentally to the balancing of the fans, and which serves markedly to reduce any produces a more quietly operating fan. Yet another object is *attainedin animpr'ovedbalancing and silencing method and-means which do not in any way 'afiect the external appearance of either the blades or the spider arms, as is the case with certainbalancing andsilencing ex pedients heretofore employed."-

' 1 A still further object "of the invention is attained in an improved resonance-damping expedient, through the structural interconnection of the blades'proper, and which is particularly adapted to 'propeller type fans characterized by a relatively small number of blades. v 1 1 An important additional objectisattained in a fanqn'ou'nted guard structure, which serves as a measure of protection against personal injury by tending 'to' prevent casual introduction of 4 fingers or clothing to the spaces between the blades; this object being conveniently realized by bladeinterconnecting elements which also serve-to dampen'blade" vibrations. a l 'I'he foregoing and other objects will appear from the following detailed description 'of a'presently preferred embodiment of the invention, considered in' connection with the accompanying drawing, in which:

Fig, 1 is affront l'evation' ofaftl'iree-bladeventilator "fan to'wl'iich the'present' improvements are applied; Fig. 2 is a fragmentary rear elevation of a center disc, one of the blade arms and a portion of'theblade secured thereto; Fig.3 is an enlarged fragmentary sectional elevation longitudin'ally of one of the'blade arms and the'ico'nne'cted blade, this view being taken in" a} plane normal to the intermediate areaof the-"blade, and as viewed along line 3-5-3 (if Fig.1: Fig. 4 is a fragmentary section taken transversely of one of the blades and the associated blade arm. the location of this section being indicated by line 4- 4 of Fig. 2; FigLS is' a fragmentary sectional elevation through and alonga' margin of one of the blades, as viewed along line*5'5 of Fig. and.Fig 6 is a, front elevation'of a fan "similar to that shown'by Fig.v 1'," but illustrating 'a, modified fonn of vibration dampening 5 and blade guard structure.

,Referring now by characters" of reference "to the drawing, there is shown by Fig; 1 apropller type fan assembly,jt he features of which are susceptible of use in fans of a substantial range oi' sizes. .The fan as shown embodies a relatively heavy metal center disc I I) provided'with a central shaft Opening, (not shown) and into which is inserted'a metalhublorhub sleeve H provided tendency to" resonance, and thus with a retaining shoulder HA and a swaged or spun over portion i2 through which the disc is secured to the hub. The fan assembly is mounted for rotation on a shaft I! which is or may be of conventional arrangement, and which is usually, in fans of the noted type, belt-driven from a motor or other suitable prime mover (not shown).

In the disclosed example, consisting of a threeblade fan, the center disc Ill serves as a support for three blade arms il. Each of these blade mounting elements is characterized by a planar portion ll, secured as by rivets Ii or the like, to the disc l0. Each of the arms is twisted as at H in a zone slightly radially beyond the disc Ill, so as to provide the predetermined pitch angle of the blade carried by the associated arm. Beyond the twisted portion is found an outer planar portion to which is secured the blade 2|, as by the rivet or like elements 22.

Each of the blades may be broadly designated as of shovel form, characterized by a substantially rectangular outline, with rounded outer corners, through the outer portion of the blade, when viewed in plan,- the inner end of each blade being of a substantially regular arcuate contour as shown. The exact shape of blade is, however. not material to the present improvements, but in order further to describe for completeness, the blades illustrated, it may be noted that each thereof is characterized by a forwardly turned lip 23 on the outer leading edge portion of the blade, an intermediate, substantially planar portion 24, and a relatively sharply forwardly turned part or trailing margin 25. The leading and trailing portions 23 and 25 respectively are demarked from the intermediate portion as by substantially rectilinear zones 20 and 21, each of these zones of folding or bending extending at a slight acute angle to a radius on the axis of shaft l3, from which it results that each blade presents a channel which is of a trend at an acute angle to a radius, in accordance with the disclosure and claims of Letters Patent No. 2,021,707 and 2,072,- 322 of this applicant, issued respectivelyNovem- .ber 19, 1935, and March 2, 1937.

The present improvements contemplate the optional provision in each of the blades, of a substantially radial groove, flute or channel 30, as shown by the section of Fig. 4. when employed, this groove is preferably die-formed in the blade at the time of shaping or bending, and is ar ranged so that the groove or flute is presented as a radial depression in the rear side of the blade. resulting in a radial projection on the forward side or surface of the blade. By preference, the grooves'or flutes each extend from a point about midway of the length of the blade, fully to the inner end thereof.

Each of the spider arms or blade mounting elements is, by preferance, similarly characterized by a longitudinally fluted portion or channel formed in the arm at the time of stamping or shaping the arm, the flutes, channels or grooved portion of each of the blade arms being indicated at II. It is to be noted as a preference that the grooves or flutes of the several spider arms, ex-

tend the full length thereof and approximately along median lines of the respective arms. As

best appears from Figs. 3 and 4, the assembly of each blade and the associated arm is such that the companion grooves 30 and ii are relatively oppositiely disposed, i. e., with the two grooves facing each other, so that when the groove 30 is utilized, the two grooves 30 and ii coact to form a radial pocket, channel or tube. between each blade and the arm to which it is assembled, this relation best appearing from Figs. 3 and wherein the pocket or radial chamber is indicated at 32.

The tubular chamber or pocket 32 serves, ac cording to the presently described means of balancing a fan, as an elongate chamber for the reception of units of a balancing material, and according to preference, this material consists of some suitable rod stock, such as a steel wire or like material, which may be easily cut into desired lengths and thus arranged in units of desired weight;

It may be here noted that the insertion of units of a balancing material, such as indicated at 33, tends markedly to reduce any tendency to resonance which might otherwise be exhibited by the blade. The vibration-damping effect of the pellets or units in the radial channel or pocket 32, serves to impart a "dead" sound to the blade whose Weight has been augmented by the balancing material. It will be noted further that the fact of arriving at a good degree of balance by reason of the expedients heretofore described, serves of itself, to minimize unbalanced conditions of the fan as a whole, and in so doing, serves to produce a more quiet running fan than would otherwise be the case.

,A further, in some respects preferable, balancing provision is best shown by Figs. 2 and 3, as including one or more grooves 34 transverse of the blade arm, the transverse flutes, channels or pockets being best observed from the projections 35 (Fig. 2) resulting from depressions of the blade-engaging face of the arm. These channels may selectively or together be utilized to contain predetermined lengths or weights of the balancing units 23, which will serve not only their primary balancing effect, but will exhibit a secondary effect of reducing blade resonance.

In order still further to assure quiet operation of the fan as an operating unit, and to minimize resonance effects of its blades, it is preferred structurally to tie together the leading edges of the several blades, one expedient for this purpose being shown by the tie rings 40. Each of these is preferably formed as a single annular piece, preferably of heavy wire or rod stock of endless form, each ring 40 whether one or more than oneis utilized, being welded or otherwise firmly secured to the leading margins of the several blades. One example of such securement is shown by the weld zone ll, as best appears in Fig. 5.

In a fan utilizing blades of the general form of Fig. 1, it has been found that the more sharply curved upturned trailing portions 25 serve markedly to damp out any blade vibrations which might otherwise tend to occur in the trailing halves of the blades. Accordingly it is more desirable to secure the resonance damping elements, such as one of the rings 40, to the leading edges of the blades, as shown. This arrangement has the further advantage of creating less adverse air disturbance and turbulence effects in the slip stream from thefan. I

As a result of experiments with tie elements located in securement to different radial zones of the blades, it has been found that a member such as ring 40, is most advantageously disposed in securement to an intermediate portion of the leading edge of the blade, i. e., neither too close to the inner end of the blade, nor too close to I the zone of securement of blade and blade arm, yet not too close to the outer periphery or tips of the blades. The latter because of their higher lineal velocity, will be affected to a greater extent in their displacement characteristics, than will the intermediate portions of the blades to which each of the rings is secured as in the disclosed example.

It will be understood, of course, that instead of a single or multiple arrangement of unitary ring elements such as 40, separate tie elements may be employed for the purpose of interconnecting the various blades. One such arrangement is shown by Fig. 6, wherein three separate arcuate rods such as 50, serve as tie elements between the blades, each member 50 serving to bridge the leading edge of one blade and the trailing edge of an adjacent blade, securement of the tie rods being effected as by welding in the zones and 52, after the manner of the weld zone 4i (Fig. 5) or by any other suitable fastening expedient.

The manner of application, and the resonancedamping effect of the tie element or elements such as 40 or 50, will now be at once apparent to those skilled in the art, without requiring any description of assembly or function.

The manner of use of the wire or rod stock or other material for the purpose of perfecting the balance of the fan will, similarly from foregoing description, be apparent to those skilled in the art of balancing propeller type fans. The fan rotor, being the assembly of blades, blade arms and center disc, or in lieu of the arms and disc, a spider element, may be tested by methods well known in the art, wherein the degree and nature of unbalance is quantitatively determined. Following this determination, balance weights may be tentatively applied to the fan. The selected length of the rod or wire unit is then inserted, either into the upper end of the pocket 32, or the end of channel 34, or both. The balance may then be redetermined, and if minor adjustment is necessary, the location of the balancing unit may be radially shifted in the pocket 32, by moving it inwardly or outwardly thereof, or may be shifted or substituted by another unit in groove 34. With the optimum location of the correct weight of the unit or units of balancing material such as 33 in one or more of the grooves, it is preferred that the location of the balancing unit or units be fixed by upsett ng, deforming, or inwardly displacing spaced portions of the metal defining at least one of the grooves 30, 3i or 34.

In any event it is preferred that the inner end of the chamber 32, if occupied. be inwardly deflected as shown at 42. Similarly, the outer end portion'of the groove formed in the spider arm, for example as shown at 43 may be inwardly depressed or deformed so as to constrict the ends of the radial pocket or chamber 32. It will also be found desirable in some cases, to depress an intermediate portion of one or more of the grooves, as indicated at 44, which upset portion of the metal serves to retain the unit of balancing material in its intended position between the blade and blade-supporting arm. It will have appeared of course that it is desirable thus to fix the location of the balancing units in such of the chambers 32 or 34 to which they are applied, after the correct amount and positioning of the balancing metal has been experimentally determined.

Referring further to the fan construction, the fans of the type herein described, to illustrate the invention, were first constructed by utilizing a single blade arm for each blade, and so operated fully satisfactorily. It was thereafter determined that the provision of two parallel blade arms for each blade, enhanced the rigidity of blade mounting, and tended further-to reduce blade resonance and vibration. The improved arrangement is illustrated by Fig. 1, wherein the blades are each disposed between paired cooperating blade arms, the forwardmost arm being indicated at l4 and the rear arm at A, the latter being somewhat longer, and by preference'being locating each of th rings 40 eccentrically of thefan. with the ring centers diametrically opposed or offset. Thus by using two or more such rings a balanced relation of the structure may be attained, guarded. Obviously a single ring, concentrically arranged on the fan, will serve a similar purpose, but less effectively as a guard, as is true of the kindred structure of Fig. 6.

It will have appeared from the foregoing description that the various features of the invention serve admirably to attain each and all of the objectives hereinabov expressly pointed out, as well as others implied from the ensuing de scription.

Although the invention has been described by making a somewhat specific reference to the various parts of a preferred embodiment, this description is to be understood in an illustrative and not in a limiting sense, since many changes may be made in the parts, their combinations and arrangements, without departing from the full intended scope of the invention as defined by the claims hereunto appended.

I claim as my invention:

1. In a propeller type fan, a spider including a spider arm, a blade assembled to the arm, the blade and arm having depressed portions in their adjacent areas, the depressed portions coacting to form a substantially closed chamber between the assembled blade and arm, and an element of balancing material laterally confined under compression in said chamber.

2. In a propeller type fan, a spider including a spider arm; a fan blade assembled to said am, the blade and arm each being grooved or fluted and the elements being assembled with their grooves or flutes in opposed relation whereby the assem bled bade and arm coact, in their grooved portions, to form an elongate, open end chamber, and an elongate element of fan-balancing material disposed with at least a portion thereof in compressed condition for its retention in said chamber.

3. In a propeller type fan, a spider including a spider arm element, a blade element assembled to the arm element, one of said elements being grooved or fluted to form with the other element, an elongate open end chamber adapted for the reception .of an element of fan-balancing material. a rod-like counterbalanclng element in said chamber, and the ends of the grooved portion of at least one of said elements being so shaped as to retain the counterbalancing element in said chamber.

and the spaces between blades well 4. In a lfan construction, a spiderarm,'a blade assembled thereto,. the blade and arm being formed in adjacent areas to provide a tubular chamber .therebetween, an elongate element of fan balancing material in said chamber, and portions oi one of the chamber-forming elements being shaped,- to prevent shifting of the element or balancing material in the chamber after the f fan assembly is broughtto balanced condition.

5. 4 fan construction for the reduction of resonance, including a spider having a plurality of spider ,arms, a ran blade assembled to each of said arms, a radial groove or flute formed in i each bladefadjacent the spider arm and. enacting therewith, to form an elongate tubular chamber, an element of balancing and resonance-reducing material innone or more 01' said chambers, with the grocve'for said element constricted to retain the element therein, and an annularjmember secured to' and carried by the leading edges or the several fan blades for the further reduction of blade resonance.

6.,In a propeller type fan, a construction for thereduction oi! bladeresonance including companion opposed radial grooves formed in each of thespiderarms and opposed companion grooves in each of thefan' blades, the. grooves extending v in a general radial direction and the grooves 01 I each spider arm and associated bladecoacting' to form a" tubular chamber, a resonance-reducing element in one or more of the, chambers, certain of the' chamber-forming portions being constricted adjacent the element therein ior'flxlng" the position of the element in the chamber, and a ring secured to the leading edges 0 each of the blades, radially outwardly ot the,spider and substantially inwardlyoi the periphery oi the fan' 7 7. In a means therefor including an arm along each provided by a radial channel formed along each blade, adjacent the arm, a rod element a press fit for its retention in the tubular chamber provided .by the channel and blade arm, and

i ring element secured to the leading edges of;

several blades'oi thefan, the ring element being of a diameter to'dispose it radially out wardly of the zone of ,securement'oi the blade arms to the blades.

8, In a propeller type fan, a plurality of blades,

' means for mounting each or the blades on a shaft propeller type fan, blades and mounting" .40 blade, means for minimizing blade'resonance,

being presented towardthe blade, and coactins with'the blade to form a chamber adapted ior'the reception and retention of a unit of balancin material, said chamber'being characterized by a constricted portion, and a unit of balancim material in the chamber and fixedly positioned therein by said constricted portion.

9. The combination stated in claimB, further" characterized by a channel the axis oi which lies along the blade-carrying arm, the channel opening into the blade-engaging race 01 the arm, and

aunit or balancing materialin the channehthe channel and adjacent blade portion coacting in assembly to enclose said unit, and having a portion of the material near the unit, deformed to preventshiitingfof the unit'in the channel. I

10, In a propeller type fan, a plurality of spacedblad'ea-blade mounting means by which the blades are supported for rotation, and 'a combinedia'n' guard and resonance-damping structurecomprised ot a plurality of rings, said rings being secured to and carried by the blades.

and. eccentric'ally mounted on the fan'with.re--

spect to the axis of rotation.

- liI n a prope ler. ype spaced 'met al blades, blade mounting means by which the blades are supported for rotation, and

a combined tan guard and resonance-damping structure comprised oi a plurality of rings, said rings being secured to and carried by the blades,

andeccentrically mounted on'the' fan with re-' spect'to t he axis of rotation, a pair or said rings being so positioned with respect to'each other:

and 'withirespect to the tan, in-amanner to maintain the running balance or the Ian.-

12. Infa propeller type fan, a plurality of blades, means for'mounting the blades for-rotation, as on a shaft, and means bridging the spaces. between the blades and including a pair of ringelements carried bythe blades, intermediate portions or thering elements being mounted with their centers on diametrally' opposite sides of the axis of revolution of the an to preserve the running balance oi the tan. and in overlapping relation to extend the blade-guarding effect of the rings,

I WALTER L. UPSON..

Ian; a-plurality 'of I

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