US1638129A - Fan blade - Google Patents

Description

Aug. 9 1927. 1,638,129

K. L. PARKER FAN BLADE Filed Sept. 21, 1925 2 Sheets-Sheet 1 Patented Aug. 9, 1927.

UNITED STATES PATENT OFFICE.

KING L. PARKER, OF ST. LOUIS, MISSOURI, ASSIGN OR TO THE EMERSON ELECTRIC MFG. (70., OF ST. LOUIS, MISSOURI, A CORPORATION OF MISSOURI.

FAN BLADE.

Application filed September 21, 1925. Serial No. 57,575.

This invention relates to improvements in fan blades, and consists in the novel construction hereinafter disclosed.

An object of the invention is to provide 6 a fan blade having its surface so curved that a substantial increase both in the dispersion and thrust of the air currents produced thereby will result.

7 A further object of the invention is to pro- 1 vide a fan blade having a surface curvature whereby provision is made for increasing the development of the air currents by a greater degree of blade curvature near the axis of rotation resulting in a more nearly equal distribution of the air currents.

Additional advantages of the construction of the invention will be readily understood from the following detailed description thereof taken in connection with the accompanying drawing in'which Fig. 1 is a plan view of a blade attached to one arm of the spider.

Fig. 2 is a diagrammatic view illustratin the curvature of the fan blade, the curved segments being cross sections taken on the construction lines of Fig. 1.

Fig. 3 is a front view of one of the blades attached to an arm of the spider.

Fig. 4 is a front edge view of the same part.

In the embodiment of the invention illustrated in the drawing, the fan blade is shown as attached to a spider -1, it being understood that the spider has a plurality of arms,

and that it is carried by a rotating member 2, as is usual in electric fan construction.

The blades proper, only one of which. is illustrated in the drawing, are riveted to the respective arms of the spider by rivets 3, said 4 rivets being in alinement. An extended line passing through the axis of the rotating member and through the rivets, and extending to the outer edge of the fan blade for the purpose of convenience of the description, will be referred to as the rivet line of the fan blade, and is indicated in Fig. 1 by the radial construction line.

By reference to Fig. 2, diagrammatically illustrating the curved surface of the blade, it will be noted that the portion of the fan blade to the left of the rivet line has a substantially uniform downward deflection having a relatively small degree of curvature. In other words, that portion ofthe blade indicated by 4 on the drawing is substantially fiat with a slight downward deflection from the rivet line. This area of the blade is on the side in the direction of rotation of the fan, and the marginal edge-of the area is the leading edge of the blade when in operation.

That portion of the blade lying to the right of the rivet line and bounded on its outer extremities substantially by the construction line with the numeral 4 above it, and indicated in the drawing by the reference numeral 5, has a relatively sharp degree of curvature from the rivet line, the maximum degree of curvature lying substantially between the construction lines 2 and 3 at the marginal edge of the fan. This area of the fan blade, inasmuch as it is closer to the axis U of rotation, has a reduced'circumferential speed as compared with the outer extremity of the fan blade. The upwardly turned curved surface 5, having a greater degree of curvature, tends to compensate for the reduced circumferential speed of the blade within this area. The result is that by the greater curvature of the fan blade an increased amount of air current production results as compared with the volume of the air currents produced near the outer extremity of the blade as a direct result of the curvature of the blade.

That portion of the blade lying to the right of the rivet line and beyond the construction line 4, and indicated onthe drawing by the numeral 6, has a less degree of curvature substantially graduated outwardly in proportion to the distance from the axis of rotation. This is apparent from the diagram of Fig. 2. The result is'that as the circumferential speed of the area of the blade is increased the degree of curvature is complementarily reduced. This further tends to equalize the thrust of the air current produced by the revolving blade when utilized in fan construction.

The marginal contour of the blade is not essential, but the invention consists in so proportioning the surface contour to the circumferential speed of the blade in operation as to result in equalized and uniform thrusts of air currents produced throughout the radial length of the blade. Practical use of the invention has demonstrated a very substantial increase both in the thrust and I edge of the fan blade,

dispersion of air currents PIOQUCBd. by afan equipped with the blades embodying the invention. 7

A limited departure from the exact curvature shown is permissible, but any substantial variation reduces to an appreciable degree the efiective results of the blade construction, and the structure of the invention may be modified to some degree without departure from the spirit and scope thereof.

What I claim and desire to secure by Letters Patent is 1. A fan blade comprising an area downwardly deflected from a plane of a median line, said area terminating in the advanced an area adjacent to the inner edge of the blade having a relatively sharp upward curvature at its marginal edge, and an area lying adjacent to said first named areashaving a curvature gradually reduced in degree proportionally to the distance from the axis of rotation.

2. A fan blade having a curved surface, the advanced area of which is downwardly deflected and the trailing area of which is upwardly curved, having the maximum degree of curvature adjacent to the axis of rotation and having a gradually, decreasing degree of curvature toward the outer marginal edge of the blade.

- KING L. PARKER.

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