US499673A - Exhaust-fan - Google Patents

Description

(No Model.)

J. E. GREEN.

EXHAUST FAN.

No. 499,673. Patented June 13, 1893.

%ZWEM EK IJV'I/ZJVIOJZ UNITED STATES PATENT Enron,

JAMES E. GREEN, OF ST. LOUIS, MISSOURI.

EXHAUST-FAN.

SPECIFIQATION' forming part of Letters Patent No. 499,673, dated June 13, 1893.

Application filed October 31, 1890- Serial No. 369,940- (No model.)

To all whom it may concern.-

Be it known that I, J AMES E. GREEN, of St. Louis, Missouri, have made a new and useful Improvement in Exhaust-Fans, of which the following is a full, clear, and exact description.

The present fan, while having a general resemblance to fans hitherto in use, is distinguished by the shape of its blades, and by their arrangement with relation to the airinlet of the fan, and to the casing, substantially as is hereinafter described and claimed, aided by the annexed drawings, making part of this specification, in which- Figure 1 is a view showing the fan in side elevation and the casing in section; Fig.2 an edge elevation of the fan, and Fig. 3 a crosssection of one of the blades.

The same letters of reference denote the same parts.

A represents the fan, and B the casing.

0 represents the shaft to which the fan is attached. The construction is of the ordinary character saving as it is modified or supplemented by the improvement under considera: tion; and only that portion of the construction is exhibited which is required for an understanding of the improvement. The fan, in the present instance, has four blades, a, a, a, a, but any suitable number can be used. The blades are attached to the arms, a, a, a, a, respectively, which in turn connect with the hub, 00 The blades are mainly flat and, in width, extend across the width of the casing, the side edges, a a coming as near as is practicable to the sides, I), b, respectively, of the casing, but in place of the blade being flat throughout its entire width its side portions are curved forward, in the direction of the movement of the fan in its rotation, substantially as described.

An additional feature of the improvement is the arrangement of the fan blades with reference to the air-inlet of the fan. Instead of the blades being arranged radially they are adjusted respectively in planes which, when projected, intersect at right angles radial lines drawn through the center of the fan, substantially as shown in Fig. 1. In practice,

the points through which said planes pass are, preferably, about one third, generally speaking, the distance from the center of the fan to the rim of its casing. The blades extend inward to opposite the periphery of the air-inlet, and their supporting arms, a, are attached to the blades respectively at the center of the inner end thereof, and the blades at the inner end thereof are substantially square, substantially as shown, thereby minimizing the surface presented to the air in the central part of the fan.

Another feature is the relation of the fanblades to the rim, Z), of the casing above the outlet, 12 from the casing. The casing, in the respect referred to, is, at b drawn inward so as to leave only sufficient room for the blades in their rotation to pass. In practice one eighth of an inch, at the point named, suffices.

In operation the fan is driven in the customary manner. The inlet to the casing is at 6 and the direction of the movement of the fan, and of the air current caused by the rotation of the fan, is indicated by the arrows 0:, 00. By reason of the fan blades being curved at the sides thereof as described the current produced by the fan is less liable to escape between the sides of the blades and the sides of the casing, and, on the other hand, and by reason of the flatness of the main portion of the blades, the air is not concentrated opposite the central portion of the blade, but is distributed evenly in front of it. Owing to the described tangential arrangement of the fan blades the blades act advantageously upon the current in drawing it effectively through the inlet, 17 into the casing, and then in impelling it through the casing and discharging it through the outlet b The blades thus arranged act to throw the current outward in the direction of the rim of the casing as well as forward in the direction of the outlet from the casing, and there is no back-action through the inlet, and as a practical result the capacity of the fan is large in proportion. to the area of its blades and the rate at which the fan is driven. The efficiency of the fan is further increased in consequence of the described contraction of the casing at the outlet therefrom. Much less of the current is carried around again with the fan than is the case when considerable space, as hitherto has occurred in the construction of fans, exists between the casing and the outermost point reached by the fan-blades in their rotation. Each of the above described features of the improvement is valuableirrespective of the presence of the other described features. But either two, or all, of them, in combination, are still more useful, and the best results are obtained When all of them are united in one construction, substantially as shown.

I claim- An exhaust fan combining in its construction the casing, the shaft, and the fan, said casing having the described air inlet at the center of the side thereof, and the blades of

Images