US2100994A - Fan guard - Google Patents

Description

Nov. 30, 1937. J. H. COHEN 2,100,994

FAN GUARD I Filed Feb. 6, 1936 llll Patented Nov. 30, 1937 UNITED STATES 7 2,100,994 FAN GUARD Joseph H. Gohen,,Bridgeport, Conn, assignor to Casco Products Corporation, Bridgeport, Conm, a corporation of Connecticut Application February 6, 1936, Serial No. 62,562

13 Claims.

This invention relates to air circulating fans of the screw type in which air is impelled in a substantially axial direction by a rotary fan or impeller, and is more particularly concerned with guards for fans of this typ The improvements of the present invention find particular application to fans adapted for use in conveyances, and to fans for household and similar uses.

There have been proposed heretofore various types of guards adapted toprotect the fan blades from damage due to falling objects, or due to falling of the fan itself, but these guards did not prevent the hands or fingers of persons from coming in contact with the rotating blades, and therefore there existed a hazard to people, and especially to children, which was a decided menace.

There have been also proposed in the past guards for preventing persons from touching the rotating blades of a fan, but these have for the most part seriously impeded the air stream, and thereby interfered with the effectiveness of the fan.

It is an object of the present invention to overcome these disadvantages by providing an improved guard for fan blades which will prevent casual or accidental touching of saidblades by persons nearby, eliminating inadvertent injury to fingers, hands, and other parts of the body, and yet which will not hinder the air stream coming from said fan but will impart a swirling and distributive movement to said stream, increasing thereby the efiective area over which air-willbe circulated. c

It is a further object of the present invention to provide a fan guard which is at once light in weight and sturdy in structure, and which is simple and economical to manufacture, and can be easily attached to the structure of said fans.

A still further object of the present invention is to provide a fan guard which will present a pleasing and workmanlike appearance in conformity with the nature of the device it is intended for.

A feature of this invention is the use of inexpensive sheet metal for the several parts of the fan guard.

Other advantages and features will hereinafter appear: r

In the accompanying drawing:

Figure 1 is a front view of the fan guard of cage when side.

Figure 3 is an enlarged fragmentary section taken on the line 3-3 ofrFigure 1, and shows in detail how the radial members are twisted.

Fig. 4 is a rear view of the fan guard detached from the fan motor frame, and showing the mounting means. 7

Fig. 5 is a section taken on the line 5-5 of Figure 4 but exclusive of the fan blades and showing separately the two parts of the guard. V

The fan blade guard of the present invention comprises a front and circumferential protective cage l0 and a rear protective and supporting frame H. s 7

The cage I0 is preferably stamped from one piece of sheet metal and then formed over a die and includes a small front circular portion [2 having a strengthening rib l3 in its face, said portion forming a center from whichv radiate curved stays M which extend to a rim flange l5.

Although sixteensuch stays are shown in the, drawing it should be understood that either more or fewer may be used; however the number shown has been found to be particularly satisfactory.

The rim flange I5 is angular in section, and integral with said flange are ties l6 extending rearwardlyof same, and terminating in a second annular rim or ring l1, and saidties. together with the flange l5 and ring I! form the circumferential portion or section of the present fan guard.

The stays l4 radiate from the center l2 in a slightly rearward direction and are slightly curved longitudinally, thereby causing the front portion of the cage I0 to outline a convex surface, and also giving a pleasing appearance'to said viewed from the front andfrom the In order to provide for strength and rigidity the stays M are crowned or laterally arched, and said stays are twisted as a whole at the points l8, l8 so that they are not broadside to the fan bladeslB, but are angularly disposed atother than a inclination with respect to said blades, thus not hindering the air stream' coming from the blades, but imparting Va swirling -motion thereto. i

As shown, the lateral arching of the stays I4 is such that the resulting concavities thereof face. the fan blades, while at the same time the aforesaid longitudinal curving of said stays is such as to have the concavely curved side edges thereof first receive the fan-generated air stream. Re-

ferring to Fig. 3, such concavely curved'side edgeof a stay i4 is indicated at Ma, and the other or.

ponvexly curved edge thereof is indicated at b.

As indicated in Fig. 3, the fan is illustrated as rotating, as usual, in a clockwise direction when viewed from the front, that is, in the direction of the arrow F of Figs. 1 and 3. The air stream from the fan is, all around the latter, discharged in a direction diverging away from the fan blades, which direction of divergence is at once toward a point ahead of a fan blade and at, an oblique angle to the front of the fan, as indicated by the arrow A of Fig. 3. Thus, all around the fan, as such air stream strikes a stay I4, it is split at that stays concavely curved edge I ia, so that part of said stream sweeps over and part sweeps under the lateral arching of the stay. ,These two air stream parts are acted on by both. of theside edges Ida. and Mb of the stay, in a way to add a special swirl impetus to theair blastfrom the fan and one causing a wide diffusion thereo fgen'erally radially of the fan. The special swirling and diffusion impetus given to the fan-discharged air is augmented by the fact that the sides Ma and MD of each stay l4, whileresp'e'ctivel'y concave and convex relative to the stay which includes them and which extends generallyradially of the axis of thefan-rotation, are both 'c'oncavely as well as curvilinearly extended relative to a fan blade advancing toward said stay. The special swirling and diffusidn impetus given to the fandischarged air is further augmented by the fact that the stays M are laterally arched, with the convexities of each such arching facing an' advancing fan blade. a a

This swirling movement which tends to distribute evenly the air stream is further augmented bythe concavity of the surface which said stays present to said air stream, and the total effect of the stays is to considerably extend the space or area wherein effective air circulation is accomplished. 'f Theabove described cage lll as provided by the present invention is thus se'en-to be extremely light in weight, and.yet,l due to the crowning and twisting .of the curved stays [4 and the ribbing of the center piece l2 to be particularly strong and rigid.

Becauseof its one-piece sheet metal construction, the material costsfor fabricatingsaid cage are low, and the manufacturing operations few and simple, there being required only to stamp out, the blank, and to form thislatter overa die, in i order to obtain the cage as shown. V

The rear portion ll of the fan guard of the present invention is also stamped fromonepiece of sheet metal, and formed over a die and comprises arim flange 20;of.angular section from which extend inwardly stays 2| and supporting arms 22, said stays and supporting arms being integral with concentric rings 23 and 24 which lie in the same planegwith the rim flange 20, the ring 24 being innermost.

The ring 23 is located-intermediate of the ring 24and the rim flange 20, andsaid rings are supported at diametrically opopsite points by the stays 2| which terminate in the ring 24.

The supporting arms 22 which also support the rrings 23 and 24 are ribbedor embossed for rigidity, and extend inwardly beyond the innermost ring 24, terminating in integral apertured bosses :25 adapted to be held by screws forming part of the fan motor frame;

tached to the frame of a fan 'm'otor, and to be supported thereon, and said portion has also the advantages of low cost and simplicity of manufacture as outlined for the cage Ill.

The rim flange 20 of the frame I i fits into the rim I! of the cage l0, and said flange and rim have corresponding apertures 26 at intervals for receiving rivets 21 which fasten the flange of said rim.

During the assembly of the guardunit, the fan blade 26 is first inserted in the cage Ill before this latter is riveted to the supporting frame I l The fan guard of the present invention is held and supported on the motor frame by screws 28,

which pass through apertures 29 in the bosses 25,

and which hold said bosses tightly to said frame.

It will be noted therefore that by the present invention there is provided a fan guard comprising in its preferred form, a front portion which has curved radial stays, a circumferential portion which has longitudinally extending ties, and a rear portion having concentric rings and radial supporting members and that the various elements of'these portions are provided in such numbers, and are so shaped and positioned as to adequately protect persons'in the vicinity of the fan against inadvertent contact with the rotating blades thereof, and possible consequent injury. While it is now preferred to have the front and circumferential sections integral, as shown, they could be made as separate portions.

At the same time there is no undue retardation of the air flow from the fan blades, air being easily suckedin through the rear por-" tion and impelled outwardly through the front portion of the fan guard because of the absence of large and impeding members in these;

It will be further noted that the curved radial stays of the front'portion, which are anguiarly disposed with respect to the axis of the fan blades, augment the naturally swirling movement imparted to the air stream by said blades, and therefore tend to distribute widely said air stream without hindrance or drawback to the velocity there- Various spacings between the several elements of the fan guard portions may be employed, of course, but preferably the radial stays of the front portion are at their outer extremities one inch apart, and the longitudinal ties of the circumferential portion matching with and joining the extremities of the radial stays, and the concentric rings of the rear portion one-half inch apart.

Variations and modifications may be made within the scope of this invention and portions of the improvements may be used without others.

I claim r V 1. A sheet metal guard for a rotatable fan structure comprising sheet metal parts presenting front, circumferential and rear sections, said front'and circumferential sections together including a front central portion, a rim flange near the front of said circumferential section, spaced stays permitting air currents to pass therebetween and extending from said rim flange to said central portion, a ring near the back of said circumferential section, and spaced ties extending rearwardly from said rim flange and joining the same and said ring; said rear section being formed of one piece of sheet metal and including a rim flange telescopically engaging said ring, and a plurality1of radial members extending iniwa'rdly'from the rim flange last mentioned for supporting said rear section on the frame of a fan motor. l

2. A fan guard asdefined in claim 1, wherein said rear section includes a plurality of concentric rings disposed inwardly of the last-mentioned rim flange, and a plurality of radial members crossing said concentric rings and merging with said rim flange for holding these in concentric relation, and for supporting said rear section on the frame of a fan motor.

3. A guard for a rotatable fan structure comprising a sheet metal cage having front and circumferential sections; said front section comprising a front central portion, a rim flange, stays radiating from the central portion and terminating in the rim flange, said stays being twisted laterally to oblique inclinations relative to the axis of the fan for imparting a swirling movement to air engaging said stays after discharge from the fan; said circumferential section including spaced ties extending rearwardly from the rim flange; means coupling the rear ends of said ties; and means for supporting said cage on the frame of a fan motor.

4. A fan guard including a front section having generally radially extending air discharge openings all around the same, there being generally radially extending stays all around said section establishing directly between each two pair of said stays one of said discharge openings, said stays being curvilinearly shaped and thereby providing means for imparting a swirling and diffusing impetus to the air stream discharged from the fan.

5. A fan guard including a front section having generally radially extending air discharge openings all around the same, there being generally radially extending stays all around said section establishing directly between each two pair of said stays one of said discharge openings, said stays being inclined across their widths at other than a right angle to the axis of rotation of the fan.

6. A fan guard as defined in claim 4, wherein said stays are also inclined across their widths at other than a right angle to the axis of rotation of the fan.

'7. A fan guard as defined in claim 4, wherein said stays are also inclined across their widths at other than a right angle to theaxis of rotation of the fan and the curving of said stays is longitudinally thereof. 7 r 8. A fan guard as defined in claim 4','wherein said stays are also inclined'across their widths at other than a right angle to the axis of rotation of the. fan, and the curving of said stays 'is laterally thereof.

9. A fan guard as defined in claim 4, wherein said stays are also inclined across their'widths at other than a right angle to the axis of rotation of the fan and the curving of said stays is longitudinally thereof, said stays also being arched laterally.

0. A fan guard as defined in claim 4, wherein said stays are also inclined across their Widths at other than a right angle to the axis of rotation of the fan and the curving of said stays is longitudinally thereof, said'stays also being arched in cross-section with the concavity of said arching facing the fan.

11. A fan guard as defined in claim 4, wherein said stays are also inclined across their widths at other than a right angle to the axis of rotation of the fan, said stays being curved longitudinally with such curving so related to the direction of rotation of the fan that the concavely curved side edges of said stays are their leading edges relative to the air stream discharged by the fan.

12. A fan guard as defined in claim 4, wherein said stays are also inclined across their widths at other than a right angle to the axis of rotation of the fan, said stays being curved longitudinally with such curving so related to the direction of rotation of the fan that the concavely curved side edges of said stays are their leading edges relative to the air stream discharged by the fan, said' stays being in cross-section arched. 7

13. The invention as defined in claim 1, in which said stays are substantially radial and longitudinally arched and of curved cross-sec tion. 7

JOSEPH H. COHEN.

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