US2742225A - Oscillating fan - Google Patents

Description

April 17, 1956 N. J. GUARDADO OSCILLATING FAN 2 Sheets-Sheet l Filed June 11 1951 V x l l l l I INVENTOR April 17, 1956 N. J. GUARDADO OSCILLATING FAN 2 Sheets-Sheet 2 Filed June 11 1951 Nesl'or J. Guardado The object of the present inventionis `an oscillating *fan characterized by the fac't thatthe assembly formed by the motor and blades` is mounted within a suspension `system capable of freely swinging in three directions,

i. e., a gimbal-type suspension. Y

The three orthogonal axes coincide. at a iixedpoint in space, said point being, at the same time, the barycenter of the system. Y

The fan body is provided with a trunnion projecting therefrom and contacting a yguide fixed kto the foot of the fan. Said guide, at its side confronting the trunnion, possesses a spherical cap shaped recess, the centerwof which coincides with the barycenter` of the system. A

The contour of this recess maybe a closed wfigure, such as an oval or any other figure over which Vsaid trunnion may travel.

Bearing in mind that the fan constitutes a rapidly lrotating mass,` its behavior is 4that-,of a gyrosc'opegand, therefore, taking advantageof the gyroscopes wellknown tendency to place its axis in parallel relationto` the attracting moment, vit is possible to apply to same an alternative couple that causes the fan to oscillate. f

This particularity olers two well-donned possibilities, which are: l v

(1) A compound oscillatory motion, i. e., the fan axis can be made to describe a combined oscillatory movement, swinging in a'horizontal as well Vas in a vertical plane. Y. j, i

`(2') Inasmurch as the system chosen has no direct mechanical connection with the motor, same is especially indicated in the case of fans, particularly small ones which, precisely due to their reduced size, are lowpowered and whose efficiency (volume of air set in motion) is remarkably reduced through the usual methods of gear reductions, etc. With the present system, the only energy consumed is that required to overcome the friction present in the moving parts. From the practical point of View, the energy employed in motion is neg ligible.

The -following advantages are thus obtainable:

(a) Greater area swept by the air cone.

(b) Simple mechanical execution, devoid of wear.

(c) Reduced cost as Vcompared with the classic methods applicable to cheap, low-powered types of fans.

The invention likewise envisages other accessory objects, as will be made clear in the course of the present specification. Y

In order that the present invention may be easily under stood and readily put into practice, a preferred embodiment thereof will now be explained with particular reference to attached drawings.

In the drawings: -v

Figure l illustrates an endwise view partially in section, showing the mounting of the gimbal suspension and the arrangement of the guide enabling displacement of same in a compound oscillatory movement. v

Figure 2 is a rear' view of the fan.

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Figure 3 is a plan view showing the particular shape of the guide recess.

Figure 4 is an end view of a fan equipped with a specially shaped guide permitting oscillatory motion in pa substantially horizontal plane. t

Figure 5 is a plan view of the fan illustrated in Figure 4.

Like numerals representlike or similar parts throughout the several figures of the drawings.` l

As can be seen from the illustrations, fan lis mounted in a universal or gimbal suspension, i. e., a system having freedom .of movement in three directions: oneaccording to the motors ownrotation and two further rotations in normal planes. The three orthogonal axes of rotation xx', yy and zz pass through'a point that is xed in space andwhich coincides with the barycenter of the system.v l y A It is well known that if a couple of forces is applied in a plane Z, X, see Figure l, a movement calledv precession is obtained on axis Z, said movement being one of rotation'. If M be the couple applied and I the moment of inertia of the rotor mass and t the angular speed of, rotation of the fan, a rotation tt will then appear, as given by: y r

as .per axis ZZ. f

The `greater the impudse (1.o), the morernegligble becomes the :second-the'oscillatory-term.

If it be required that the movement be a` simple swinging motion, the guide can be made merely as a circular sector 2,-Figure 4, having the centre of its curvature in theaxis (ZZ) y and an aperture a, Figure 5, equal to the angle of rotation desired. Theosides of the gudeare sur-faces of 'a truncated cone the vortex of the Vgeneratrices of which is the centreof rotation. of `the system. Guide 2 forms `integral part of the standard or base 3 of the It is provided, furthermore, with a control arm .or trunnion. 4 forminginteg'ral. part? of 'the fa'n 1. and resting on guide 2, the direction of which is that of a generatrix. The presence of a couple of forces in the plane ZX, an unexpected phenomenon when consider# quency of which is equal to the rotation of the machine p that, as it rests on the guide, Voriginates in the trunnion a force equal and contrary to the oscillatory force applied against the wall and corresponding to they supporting vibratory semicircle's, to which must be added the couple caused by the `change in direction of the impulse vector. The magnitude of the couple introduced `by the arrangement according to the invention, depends on V(l) the dynamic unbalance caused by the system; (2) the impulse proper of the machines rotation; (3) the distance of the momentary centre of rotation tothe supporting point; (4) the resiliency of the supporting trunnion; and (5) thematerials chosen for the Contact between guide andtrunnion and the friction of the con* tact surfaces in question. Y

By an adequate combination of all these factors, it is possible, in each case, to obtain an oscillation period of pre-established frequency.

Looking Vat the fan from behind, and considering that Vsame is then turning in a clockwise direction, if the ture (sinus) of the angle (Figure 4).

- 3 trunnion rests on the outer portion of the guide (placed on the observcrs side), the precessional rotation will take' place over axis ZZ and, seen from above, the consequent rotation will also be clockwise. f e

' Once the lend of the guide has been reached, and

owing to the fact that the motion occurs in a vertical plane, the direction in which the trunnion is supported is reversed and the fan will now turn in a counterclockwise manner. The guide, instead of a projection, can be a recess in which the supporting action on the front and rear anks reverses the rotation. Guide 2, furthermore, is designed in such a manner as to causethe swinging motion to take place according to several degrees of inclination. To that end, a series of concentrical channels is provided (5), see Figure 5, following the curva- Similarly, if we place the guide in a vertical plane passing through the momentary centre of rotation, a vertical oscillatory motion is obtained.

The moment, now, is applied along axis ZZ' and in agreement with the above described principle. The pre- Acessional movement thus takes place along axis YY and an oscillatory motion in a vertical plane is then brought about in the above explained fashion.

A' combination of both arrangements produces a combined motion, i. e., trunnion 4 will follow any guide 2 presenting a recess or a projection 6, Figure 3, representing a closed ligure and situated on a spherical cap the centre of which coincides with the centre of rotation of the gilnbal system and with the barycenter of the system.

The invention as described may be clearly understood and further explanations will not be required by those Aversed in the art.

It is evident that diverse changes can be made in the construction and vdetails of the invention without thereby departing from the sphere of the present invention, the scope of which is clearly defined in the following claims.

I claim:

l. An oscillating fan comprising, in combination, fan blades dynamically unbalanced and operable about an axis, a motor for driving said fan blades, and comprising a housing and a rotor operatively connected to said fan blades, a fan mounting element having said motor hous- Ving pivotally mounted therein, a base member, said mounting element being pivotally mounted in said base member, said fan blades, axis, motor housing, and mounting element having intersecting orthogonal axes, said fan blades and motor constituting a unit having its center ofk gravity at the intersection of said orthogonal axes, a

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projection on said base, one surface of said projection being the segment of av hollow sphere having its center coinciding Ywith said intersection, closed guide means on said surface of said projection, and a control member on said motor housing in movable engagement with said guide means, said control member being fixed with re ,spect to said fan blade axis and said motor housing, whereby, upon rotation of said fan blades, said control member is caused to nutate and engage one edge of said guide means, thus causing the fan to gyrate in a path determined by the coniguration of said guide means.

2. An oscillating fan according to claim 1 wherein said projection has a series of closed concentric channels for selectively receiving said control member.

3. An oscillating fan comprising, in combination, a fan unit having fan blade elements rotatable about a first axis, the dynamic equilibrium of said elements and said unit being imperfect, a motor for driving said fan unit, said motor being operatively connected to said fan blade elements, a support, said fan unit being pivotally mounted on said support for pivoting about a second axis perpendicular to the said first axis of rotation of the blade elements, a base, a projection on said base and having one surface in the form of the segment of a hollow sphere, said support being pivotally mounted on said base for pivoting about a third axis perpendicular to the two aforesaid axes, said three orthogonal axes intersecting at a common point, said unit having its barycenter at the intersection of said orthogonal axes, closed guide means on `said segment of said hollow sphere, said sphere having its center coincident with said intersection, and a control member on said motor in movable engagement with said guide means, said control member'being fixed with respect to said motor and said fan unit, whereby, when the fan is rotating, the imperfection in the dynamic equilibrium of said elements and of said unit will impart to said control member relatively high frequency nutations which cause it to progressively engage one edge of the -guide means to advance the unit in a path determined by the contigui-ation of said guide means.

References Cited in the file of this patent UNITED STATES PATENTS vRathbun June 22, 1937

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