US1154152A - Centrifugal fan-wheel. - Google Patents

Description

E. B. WILLIAMS. CENTRIFUGAL FAN WHEEL. APPLlCATlON FILED JUNE 25.1914.

1 ,1 54,1 52.. Patented Sept. 21, 1915.

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EUGENE B. WILLIAMS, 0]? BOSTON, MASSACI'IUSETTS, ASSIGNOR T0 B. F. STUETEVANT COMPANY, OF BOSTON, MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS.

CENTRIFUGAL FAN-WHEEL.

Specification of Letters Patent.

Patented Sept. 2]., 1915.

Application filed June 25, 1914. Serial No. 847,265.

To all whom it may concern:

Be it known that I, Enenrn B. WILLIAMS, a citizen of the United States, residing at Boston, in the county of Suffolk and State of Massachusetts, have invented certain new and useful Improvements in Centrifugal Fan Wheels; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

The invention relates to centrifugal fan wheels which take the air in axially and discharge it circumferentially.

The object of the invention is to provide a fan which will act with high mechanical efficiency when driven at higher speeds than has heretofore been found practicable, and which is therefore well adapted for direct steam turbine drive.

To this end the invention consists in the features of construction and combination of parts hereinafter described and set forth in the claims.

The invention will be readily understood from an inspection of the accompanying drawings and the following detailed description of the fan wheel illustrated therein.

In the drawings, Figure 1 is a front elevation of a fan embodying the invention in its preferred form, a part of the fan casing being broken away; Fig. 2 is a vertical sectional view on line 22, Fig. 1; Fig. 3 is a detail section on line 33, Fig. 1; and Fig. 4 is a detail view showing one of the fan blades.

As shown, the fan wheel is provided with a central hub 1 by which it is secured to the driving shaft 2. A supporting back disk 3 is secured to the rear side of the hub, and supports and carries the series of fan blades at. The blades are opened to the inflow of air for most of their radial depth on the intake side of the wheel, and have their inner peripheral edges 5 inclined or tapered from a maximum diameter at the intake side to a minimum diameter at the back disk. This provides a frusto-conical intake chamber within the blades which allows free access of air to that part of the wheel nearer the back disk,'as well as to that part which is near the intake side of the wheel. To enable the Wheel to act with high mechanical efficiency when driven at periphery in toward the center.

high speed, the blades are inclined or curved rearwardly with relation to the directionof rotation of the wheel. The blade curvature in a plane perpendicular to the axis of the fan is that of the involute of a circle for the greater portion of its depth from the outer So long as the involute is preserved, a passage between two adjacent blades is provided which is of equal or uniform cross-sectional area, with a result that the losses due to expansion in the air passage and eddy currents is minimized, and the efliciency thus increased. As the blades approach more closely to the center of the wheel, the blade curve gradually departs from the involute of a circle to a curve or circle of relatively small radius. This renders this part of the blade more effective in impelling the air, and since its speed of movement is relatively very low at this point, the blade may be thus shaped to act more effectively in carrying the air forward than w-ould'be the case were the involute curve continued to the inner edge of the blade without impairing the mechanical efficiency of the wheel. In the construction shown, the curvature of the blade follows approximately the involute curve to substantially the point indicated at 6 in Fig. 1, and here merges with a circle of comparatively short radius, so that the curvature at the inner point of the blade is approximately radial of the wheel.

The intake ends of the blades are secured to an annular ring '7, and the blades are strengthened and their form preserved against the centrifugal strains developed when the wheel is run at exceedingly high speed by annular rings 8 which are set into notches or recesses cut in the outer peripheral edges of the blades. The blades are secured to the rings 8 by angle irons 9 and bolts 10, as indicated in Fig. 3. The rings 8 not only strengthen the wheel and maintain the blades in proper shape against the centrifugal strain, but also tend to equalize the flow of the air from the periphery of the wheel along the axial length of the blade.

The wheel is adapted for use in any form of casing, and as shown, is mounted within a casing comprising a rear plate 11 and a front plate 12 which is provided with an intake eye 13 registering with the intake of the fan wheel.

vVhile it is preferred to employ the specific construction and arrangement of parts shoWn and described, it will be understood that this construction and arrangement is not essential to the broader features of the invention, and may be varied or modified Without departing therefrom.

Having explained the nature and object of the invention, and specifically described one form of a fan Wheel in which it may be embodied, What is claimed is l. A centrifugal fan Wheel, having, in combination, a supporting back disk, a series of rearwardly inclined blades having a curvature Which is approximately the involute of a circle for the greater portion of their depth, and a curvature of comparatively small radius at their inner portions and of rearWardly curved blades having a curvature approximately the involute of a circle for the greater portion of their depth and which merges With a circle of comparatively small radius at the inner portion of the notches formed in the outer peripheral edges of the blades, and annular rings fitting Within the notches and secured to the blades.

EUGENE B. WVILLIAMS,

Witnesses: I

' BURTON NV. CARY,

A NIE O. RICHARDSON.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents.

Washington, D. G.

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