US1980614A - Electric fan - Google Patents

Description

Nov. 13, 1934.

L. N. DAVY 5 ELEQTRIC FAN 2 Sheets-Sheet 1 Filed March 15, 1953 m m J W k 4 f \I s & 0 6 Q h 9 4 W I aw \w Nov. 13, 1934. LN. DAVY 1,980,614 I ELECTRIC FAN Filed March 15, 1953 2 Sheets-Sheet. 2

INVENTOR.

ATTORNEYJ Patented Nov. 13, 1934 UNITED STATES PATENT OFFICE ELECTRIC FAN Lynden N. Davy, Butte, Mont.

Application March 15, 1933, Serial No. 660,834 9 Claims (01. 170-159) This invention relates to electric or circulating fans of the sort which, in homes, shops and ofllces, are mainly used for circulating air in warm weather, altho they are also applied to other uses.

Such fans are ordinarily provided with propellerlike fan blades of the more or less conventional screw design. The result is that such fans draw air from behind, and throw it in a direct blast practically straight forward. Accordingly not only do such fans produce a blast or draft of air objectionable and dangerous to people upon whom it blows, but such blast, by reason of its tendency to blow papers and other light articles about, frequently entirely prevents the use of the fan,

or necessitates its being run at reduced speed and efficiency. Fans of this type have the advantage, however, of being simple and inexpensive in design and construction, whereas most devices designed to circulate air without creating such an objectionable straight blast have in the past been more complex and expensive.

My invention contemplates as an important object the provision of an impeller no larger than and readily substitutable for the more conventional fan blade assembly now commonly used, so designed as to displace, when run at the same speed as much air as or more air than is displaced by aconventional fan, but to throw a lesser proportion of the displaced air straight forward and a greater percentage outwardly angularly relatively to the axis of the fan, and to distribute such thrown air in all directions outwardly from in I front of the fan, thus moving the air throughout an entire hemispherical area centered in the impeller.

A further object of the invention is the provision of such an improved impeller for fans which delivers its greatest volume of air in a lateral direction, but the air currents generated by which are so evenly distributed that even in this area the currents are not sufficiently violent to create dangerous drafts or blow light objects about.

The present invention constitutes and has for a further object an improveinent of the fan disclosed in my previously issued Patent No. 1,820,448, granted August 25, 1931.

Other objects and advantages will be apparent from the following description wherein reference is made to the accompanying drawings illustrating the preferred embodiments of my invention and wherein similar reference numerals designate similar parts throughout the several views.

In the drawings:

Figure 1 is a front view of an electric fan provided with one of my improved impellers, with the guard cage removed.

Figure 2 is a side view of the fan.

Figure 3 is a perspective view of the impeller.

Figure 4 is a rear view of the impeller. I

Figures 5, 6, 7 and 8 are transverse blade sections taken substantially on lines 5-5, 6-6, 7-7, and 8-8 respectively, of Figure 4, and looking in the direction of the arrows.

Reference character 10 designates an electric motor, adjustably carried by a pedestal 11. The design of these elements will be seen to be unimportant, since theinvention concerns itself solely with the impeller. Carried by the front end bell of the motor is a wire guard cage 12, within which 7 and fast upon the armature shaft 13 is an impsller, the construction of which constitutes the subject matter ofthis invention.

The blades may be of sheet metal, securedto a hub spider 14 as by means of the rivets 15 which are passed thru a flat portion 16 of each blade. The portion 16 lies flat along the inner part of the leading edge in a plane normal to the motor shaft. This area will be seen to decrease in width from a maximum at the root of the blade to zero at a point (19) about one-third its length from the tip.- The straight edge 16' of the section 16 constitutes part of the leading edge of the' blade.

Adjoining the section 16 is a pitched section 17 of similar generally triangular shape and length; this may also be flat but arranged at a substantial angle of incidence, as shown in Figures 5-7. If the areas 16 and 1'7 are flat, their pitch is constant throughout their length-that so of the area 16 being of course zero. Obviously these areas might however be formed as a continuous curved section.

Adjacent and trailing the area 17 is a more sharply pitched area 18, the incidence of which also varies somewhat from its narrowest portion, at the root end of the blade, to its widest part, which is approximately in line with the point 19. As shown in the successively taken sectional views, Figures 5-8, its angle of incidence is about 100. 60 degrees at its inner'extremity, whileits continuation 20, which extends from the point 19 to the tip of the blade, approaches 90 degrees. The sharp increase in its angle of incidence is provided by the portion 20, which is bent backward'as if about a line 19 ;proje'c5t'ed-across the blade from the, point 19, alth'o actually it is preferably curved, as shown at the' portion of the drawings so designated, rather than broken along a sharp line. This also, however, is a matter of no choice. The section 20, being rearwardly bent with respect to the leading edge of the blade and arranged at a high angle of incidence, as above noted, 0! course tends to throw air outwardly more'nearly radially.

Bounding the outer trailing edge of the sections 18 and 20 is a relatively narrow marginal area 21 which has an angle of incidence of degrees throughout its entire length.

a When a plurality of such' blades are assembled to form an impeller in the manner shown, the assembly is as compact and practically oflthe same general shape as an ordinary fan blade assembly, for which the improved impeller is readily substitutable either in manufacture or as a replacement part upon an already completed .!an. In use, even when driven at full speed, the new impeller produces no concentrated blast in; any one direction, so that a person within'its sphere of influence feels but a pleasant, gentle breeze. Nevertheless the impeller actually displaces as much air as a conventional fan blade assembly driven at the same speed, and accord ingly the total circulation produced to do the actual work ofdissipating moisture and heatladen air is fully as great d as efiective, though the objectionable charac eristics of the direct blast are absent.

While it will be apparent that the illustrated embodiment of my invention herein disclosedis well calculated to adequately fulfill the objects and advantages stated, it is to be understood that the invention is susceptible to variation, modification and change within the spirit and scope of the subjoined claims.-

What I claim is:

1. A Ian blade formed or sheet material and having its leading edge portion nearest the root of the blade arranged at an angle of incidence oi approximately zero, a leading edge portion near the tip arranged at an angle of incidence of substantially ninety degrees, and connecting portions of intermediate incidence.

2. A fan blade formed oi sheet material and the inner portion of which is increasing incidence from substantially zero at its leading edge to a maximum angle near its trailing edge, while its tip portion is angularly rearwardly bent with respect to a leading portion of the blade and arranged at a high angle of incidence.

3'. A fan blade formed of sheet material and the inner portion of which, terminating at a point on the leading edge and spaced from the tip, is of increasing incidence from'the leading to the trailing edge, while the entire tip portion beyond said point is angularly rearwardly bent with respect to a leading portion of the blade and arranged at a high angle of incidence.

4. A fan blade formed of sheet material, or decreasing width and increasing incidence from its root to itstip, and having a portionnear the tip to throw air outwardly.-

' 5. A fan including a plurality of blades each having an inner portion extending the blades width and increasing in incidence from leading to trailing edge, the leading edge of said portion be- -bent rearwardly 01' a leading portion of the blade ing substantially radial, and a tip portion'rearwardly bent at an angle to said leading edge and at a high angle of incidence, said tip portion therebytending to throw air outwardly radially when the fan is rotated.

6. A fan blade having root and leading portions of low incidence, a connected trailing portion of higherincidence adapted to throw air forwardly,

and a tip portion of high incidence rearwardly bent with respect to a leading portion and adapted to throw air outwardly.

7. A fan blade having an active portion of substantial incidence adapted to throw air forwardly, and a connected tip portion of higher incidence which is also rearwardly bent with respect to a leading portion of the blade and adapted to throw air outwardly.

8. A fan blade having an active portion of substantial incidence, a connected tip portion of higher incidence which is also rearwardly bent with respect to a leading portion of the blade, and

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