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Publication numberUS1541236 A
Publication typeGrant
Publication dateJun 9, 1925
Filing dateJul 23, 1924
Priority dateJul 23, 1924
Publication numberUS 1541236 A, US 1541236A, US-A-1541236, US1541236 A, US1541236A
InventorsBruno Schmelzer
Original AssigneeBruno Schmelzer
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Protector for fans and the like
US 1541236 A
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Description  (OCR text may contain errors)

June 9, 1925. 1,541,236

- B. SCHMELZER PROTECTOR FOR FANS AND THE LIKE Filed July 23, 1924 Fl g'zl 4" I I I INVENTOR ATTORNEY Patented June 9, 1925.

outrun STATES,



Application filed July 23,

To (all whom it may concern:

Be it known that I, BRUNO SoHMuLzna, a citizen of the United States, and resident of Jersey City, in the county of Hudson and State of New Jersey, have invented a certain new and useful Protector for Fans and the like, of which the following is a specification, the same being a full, clear, and exact description of the invention, its structure, and operation.

The invention which constitutes the subject matter of this application relatesto improvements in guards, fenders, or like devices for centrifugal fans,compressors, air audgas pumps, fan blowers, and other kindred apparatus which are herein designated as fans, the rotatable parts of which are enclosed by a framework, and it has for its object the provision of an improved construction of fan guards whereby undue approach to the fun wheel is prevented.

Another object of the invention is to so shape the framework of the guard that the contour of the rear portion of the same shall correspond to that of the edge of the fan blade.

Another object of the invention isto increase the er'iiciency of such fans and to eliminate the noise ordinarily incident to the use of fan guards in common use.

A further object of the invention is that the air as it entersthe fan shall not strikethe wires forming the rear portion of the guard at a right angle.

Another objectof the invention is that a substantially unobstructed passage shall be provided for the air as it is drawn into the fan. i e

Another object of the invention is that while serving for the above named purposes it shall cost no more to make than the fan guards in ordinary use.

i still further object of the invention is the provision of a fan guard that shall be of simple construction, inexpensive to manufacture, and reliable and efficient in practical use lVith the above named objects of the invention, and other objects and purposes which will be described below, in view, the invention consists in the combination, arrangement, combination and operation of parts hereinafter set forth.

The noise produced by high speed centrifugal fans is in great measure caused by 1924. Serial No. 727,8 3?

the fluid being forced to pass over one or more sharp edges, especially where such sharp edges are at right angles to the flow of the air,avlicreupon it ceases to flow smoothly and becomes broken upinto whirls or eddies thus forming a turbulent mass which produces noise.

By the employment of the peculiar form of g' iard used by me an unobstructed channel for the even and steady movement of the fluid is provided and the above named disadvanta cs are eliminated. I

With the above-considerations in mind, and with a view of overcoming the objections pointed out,l have devised the fan guard shown in the drawings, illi'istrativc of one tilibOClllllQilt of the invention, which accompany and form a part of this specification, and in'which Figure 1 represents a side elevation of a fan equipped with my guard; and

Figure 2 is a view of the rear face of the ,Qfllfllt on a sn'ialler scale.

Referring more in detail to the drawings, the numeral 1 denotes the front face of the guard framework: 2 and 3 indicate the up-' per and lower parts of the circular body portion of the same; 4, and 41, 6 are a plurality of rear supports or braces of the guardj 7 denotes the spindle of the meter, and 8 is the hub of the fan indicated as 5'); 10 represents the front of the actuating motor, and 11 indicates the channel between the supports 5 and 6 and the blades 9 of the fan. w 4

The air at the suction or intake side of the fan, when drawn into. my guard for the latter, flows in converging radially disposed streams orpcurrents. In said passage the the path of the said incoming streams of air.

The currents now pass into the space bet een the rear portion of the guard and the fan, which space is designated as the channel 11, and is formed by the rear guard supports being radially inclined at the outer parts 4 thereof and the central portions of the same being deflected, recessed or dished, as at 5 and 6, to conform in general to the arc or contour of the edges of the fan blades in order to provide a full and free passage for the entrance of the air currents which at that point begin to have a rotary motion.

As the various currents or streams of air approach the revolving fan blades they become compressed and are drawn into the fan by suction with a much increased rotary motion in order to fill the partial vacuum caused by the expelling of the air forwardly from the fan.

In this latter movement of the air currents through the channel 11 they meet with no obstruction whatever and consequently pass through the fan with practically no noise, while at the same time the efficiency of the fan itself becomes increased. It will be noted that the channel 11 is largest at the axis of the fan thereby forming an enlarged channel posterior of the fan and affording more room for the incoming streams of air to enter the fan.

In the old type or form of fan guard ordinarily used the rear supports of the guard lie in the plane of the parts 4 of the rear guard supports. Under such a condition the many streams or currents of air have to enter the guard in a direction approximately. corresponding to the direct-ion of rotation of the fan wheel, and therefore strike the rear supports of the guard at right angles, as the latter lie so near the fan blades, which results in noise being produced by reason of the sharp edges of the guards across which the air currents must flow.

By however dishing the rear supports of the guard I attain a two-fold result; namely, first, to cause the said rear supports to lie in and parallel with the incoming streams of air; and, second, to provide a full and free passage for the entrance of the air currents into the fan without encountering any obstruction whatever; both of which advantages combine in eliminating noise in the practical operation of the fan.

I wish it to be understood that I do not desire to be'lin'iited to the particular use or the exact details of construction shown and described, for obvious modifications will occur to persons skilled in the art.

single curved line toconform to the are or contour of the surface of a fan blade but spaced therefrom to provide, by the rearwardly extending supports lying in and parallel with the path of the entering air, a free and unobstructed channel for the air of practically equal width throughout its length before it is deflected by the rotation of the fan.

2. In a device of the class described, a casing supporting a circular wire frame or disc and a plurality of radially disposed rear supports each dished rearwardly and eX- tending from the casing rim to the spindle of the fan in a single curved line to conform to the are or contour of the surface of a fan of the surface of a fan blade but spaced therefrom to provide, by the rearwardly extending supports lying in and parallel with the path of the entering air, a free and unobstructed channel for the air of practically equal width throughout its length before it is deflected by the rotation of the fan, the said channel being larger adjacent to the spindle of the fan.

Signed at New York, in the county of New York and State of New York, this 22nd day of May, A. D. 1924.


Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3282364 *Jul 31, 1964Nov 1, 1966Cramp David LMotor vehicle having frictionallydriven traction wheel
US6296449 *Apr 20, 2000Oct 2, 2001Pierce WangMultiple current safety fan
U.S. Classification416/247.00R
International ClassificationF04D29/70, F04D29/00
Cooperative ClassificationF04D29/703
European ClassificationF04D29/70C2