US2240653A - Fan - Google Patents

Description

May 6, 1941.

c. F.,JENKINS r-rr AL FAN Filed Sept. 30, 1939 I WITNESSE 607M.

INVENTORS Cficzrles ZJemm & I 21006): Z Rambo.

ATTORNEY UNlTED STATES Patented May 6, 1941 FAN Application September so, 1939, Serial Nd. 297,338

T ()E'FHQE 4 Claims.

Our invention relates to a novel type of fan which partakes of the'natures of both a centrifugal fan and a propeller-type fan. The centrifugal type of fan causes the air to rotate so that the centrifugal force of the rotating air causes it to move in a radial direction, and it has the property of delivering a relatively small or moderate volume of air at a relatively high pressure. The propeller type of fan theoretically imparts no rotation to the air, but the blades are twisted so that the air is moved in an approximately straight axial direction, and it has the property of delivering a relatively large volume of air at a low pressure.

In accordance with our invention, air is admitted, at portions of the blades which are of the centrifugal type, except that these entranceportions of the blade are not disposed in an exactly radial direction, like paddles, but they are inclined backwardly, and they are also twisted just a little so as to give the air a slightcomponent of movement in an axial direction. During the course of the length of the blades, considering length in the direction of air-flow, the blades are twisted, so that, at the exit-portions of the blades, the trailing edges of the blades leave the air in an edgewise fashion, as the blades rotate, so that there is substantially no centrifugal-fan efiect, but the blades are twisted, as in a propeller frame, so as to propel the air in an axial direction. Cooperating with these blades are flared air-directing means, both above and below the blades, for directing the air in a direction first largely radial and then curved toward an axial direction, in its passage through the bladed portion of the fan.

In the accompanying drawing- Figure 1 is a vertical elevational View of the fan, looking at the front side of the fan, or the side at which air is admitted into the fan, with a part of the shroud broken away to better show one of the blades;

Fig. 2 is an axial sectional View on a plane passing through the axis, as indicated by the line II-II in Fig. 1;

Fig. 3 is a transverse sectional view particularly showing the entrance-portions oi the fanblades, the section-plane being indicated by the line III-III in Fig. 2, and

Fig. 4 is a development of a cylindrical intercept on the fan at the exit-portions of the blades, on the line indicated at IVIV in Fig. 1.

The illustrated embodiment of our fan comprises a rotating structure including a disc or runner 5 mounted on a shaft 6 and including a portion standing out from the shaft 6. At a considerable radius out from the shaft 6, the disc or runner 5 is integrally joined to a plurality of blades 1 disposed around the periphery of the disc or runner 5, the number of blades, in the illustrated fan, being seven, although we are not limited to this precise number.

Air is admitted to the blades, on the entrance side of the runner 5, near the lower ends of the blades or the inner periphery of the bladed portion of the fan. As shown in Fig. 3, the entrance portions 8 of the'blades, or the portions near the inner periphery of the bladed portion of the fan, are inclined or disposed, paddlefashion, in a generally radial direction, so as to paddle the air around in a rotating movement, but the blades are tilted backwardly with respect to a true radial direction, so that the rotation of the blades will present an inclined surface to the air, at the same time when the rotating movement is being applied to the air, so that the air is pushed radially outwardly by the backwardly inclined approximately radial entrance-portions 8 of the blades. The entranceportions 8 of the blades are also twisted to a slight extent, in propeller-blade fashion, so as to tend to hold the air back against the runner 5, in an angle between the runner and the entrance-portions 8 of the respective blades, while at the same time beginning to give the air a slight impetus in the axial direction.

The direction of rotation of the fan is indicated by the arrows marked R, while the air-movement is indicated by arrows marked A.

Following along the blades in the direction of air-flow, starting at the entrance-portions 8 of the respective blades, it will be noted that the runner 5 is curved backwardly, that is, curved in the direction of the axial flow of the air, at points beyond the entrance-portions 8, this backwardly curved or dished portion of the runner being indicated at 9. It will thus be noted that this dished portion 9 constitutes a flared fluid-directing means, disposed below the blades 7, for so directing the air that it starts out moving radially outwardly, in the entranceportions 8 of the blades, and then is curved toward an axial direction, in its passage through the bladed portion of the fan.

To further direct the movement of the air through the bladed portion of the fan, it is necessary also to have a shroud or outer fluiddirecting portion, as indicated at it. The shroud H is disposed above the blades, and is bowed or flared out, in a curved direction, so as to guide the air as it moves, first in a largely radial direction and finally in a largely axial direction, in its passage through the bladed portion of the fan. The shroud Il may be either stationary or rotating, preferably the latter, as indicated on the drawing, wherein the shroud is shown as being an integral part of the rotating structure of the fan.

Considering, now, the shape and disposition of the blades 1, it will be seen from the drawing, that, as the air-movement progresses along the blades, starting with the entrance-portions 8, the blades will be curving backwardly, with the air-directing flared-means 9 and H between which the blades are secured, considering, now, a backward curvature as seen in Fig. 2, starting with the entrance-portions 8 at the inner periphery of the blades on the entrance side of the runner 5, and continuing on to the exit-portions l2 at the outer periphery of the blades on the exit side of the runner 5.

In the intermediate portions of the blades 7, between their entrance-portions 3 and their exitportions $2; the blades are twisted, so that, by the time the exit-portions 12 are reached, the blades are no longer disposed paddle-wise, so as to tend to rotate the air as the blades are rotated. Thus, at the exit-portions l2, the trailing edges l3 (Fig. 4) of the blades leave the air in an edgewise fashion, as the blades are rotated, so that there is a minimum rotary movement imparted to the air at this portion of the fan blades, but the blades are twisted about a radial axis, like any propeller fan blade, as is seen more clearly in Fig. 4, so as to move or propel the air in an axial direction, as the blades cut through the air as a result of the rotary movement of the blades. It will be observed that we are speaking, here, in describing the exit-portions ii of the blades, as if the blades 7 are rotating faster than the air in this exit-portion of the fan, and this is actually the case, because, while the entrance-portions 3 of the fan-blades tend strongly to cause the air to take up the same speed of rotation as the fan-blades, so as to cause the air to move radially outwardly as a resuit of its own centrifugal force due to the rtation of its particles, the paddle-like entranceportions 3 of the blades are so short, radially, and are so inclined, that all particles of the air do not achieve the same speed of rotation as the fan-blades, so that, at the exit-portions l2 of the fan-blades, the blades are still moving faster than the air, so that the above-described propeller-fan effect may be achieved.

The air is discharged from the exit-portions [2 of the fan into an air-pressure chamber I 4 (Fig. 2), this chamber being bounded by a stationary cylindrical wall or conduit l5, the front edge of which comes up close to the outer periphery of the fan, so as to guide the air in a substantially horizontal direction as it leaves the exit-portion l2 of the fan.

The result of the above-described construction is a fan, of particularly high efflciency, capable of delivering a relatively large volume of air at a relatively high air-pressure, the pressure being developed principally in the entranceportions 8 of the blades, and the axial velocity being imparted principally in the exit-portions 12 of the blade. Our fan finds its principal utility in applications where large volumes of air have to be moved through or over machinery, or in an extended system of ducts or pipes which requirea considerable pressure-head for the passage of the air, as distinguished from the free movement of air in a room, for example.

While we have illustrated our invention in a preferred form of embodiment, we desire it to be understood that such illustration is only illustrative, and not intended to be taken as a limitation of our invention to the precise details shown. We desire, therefore, that the appended claims shall be accorded the broadest construction consistent with their language and the prior We claim as our invention:

1. A multi-blade fan comprising a rotating structure including a shaft, a disc-like runner mounted on the shaft so as to stand out therefrom, the peripheral portion of said runner, beginning at a considerable radius out from the shaft, being provided with a plurality of blades, means for causing a fluid to be admitted to one side of the fan at points near the inner periphery of the bladed portion of the fan, means for causing fluid to be led away from the other side of the fan at points near the outer periphery of the bladed portion of the fan, the blades being inclined, paddle-fashion, near their intake-ends, so as to force the fluid in a direction having a strong component in a radial direction, said blades being twisted so that they are directed, near their outlet-ends, so as to force the fluid in a direction having a strong axial component, the paddle-like entrance-portions of the blades being so short, radially, and being so inclined, that all particles of the fluid do not achieve the same speed of rotation as the blades, so that the twisted outlet-portions of the blades are rotating faster than the fluid, so as to impart a strong axial thrust thereto, and flared fluid-directing means for directing the fluid in a direction first largely radial and then curved toward an axial direction in its passage through the bladed portion of the fan.

2. A multi-blade fan comprising a rotating structure including a shaft, a disc-like runner mounted on the shaft so as to stand out therefrom, the peripheral portion of said runner, beginning at a considerable radius out from the shaft, being provided with a plurality of blades, means for causing a fluid to be admitted to one side of the fan at points near the inner periphery of the bladed portion of the fan, means for causing fluid to be led away from the other side of the fan at points near the outer periphery of the bladed portion of the fan, the blades being inclined, paddle-fashion, near their intake-ends, so as to force the fluid in a direction having a principal component in a radial direction, said blades being twisted so that they are directed, near their outlet-ends, so as to force the fluid in a direction which is predominantly axial rather than radial, the paddle-like entrance-portions of the blades being so short, radially, and being so inclined, that all particles of the fluid do not achieve the same speed of rotation as the blades, so that the twisted outlet-portions of the blades are rotating faster than the fluid, so as to impart a strong axial thrust thereto, and flared fluiddirecting means for directing the fluid in a direction first largely radial and then curved toward an axial direction in its passage through the bladed portion of the fan.

3. The invention as defined in claim 1, characterized by said flared fluiddirecting means including flared fluide'directing portions both above and below the blades.

4. A multi-blade. fan comprising a rotating structure including a shaft, a disc-like runner mounted on the shaft so as to stand out there from, the peripheral portion of said runner, beginning at a considerable radius out from the shaft, being provided with a plurality of blades, means for causing a fluid to be admitted to one side of the fan at points near the inner periphery of the bladed portion of the fan, means for causing fluid to be led away from the other side of the fan at points near the outer periphery of the bladed portion of the fan, the blades being inclined, paddle-fashion, near their intake-ends so as to force the fluid in a direction having a strong component in a radial direction as well as a component in an axial direction, said blades being twisted so that they are directed, near their outlet-ends, so as to force the fluid in a direction having a strong axial component, the paddle-like entrance-portions of the blades being so short, radially, and being so inclined, that all particles of the fluid do not achieve the same speed of rotation as the blades, so that the twisted outlet-portions of the blades are rotating faster than the fluid, so as to impart a strong axial thrust thereto, the blades, at their outletends, having substantially no inclination in a direction tending to whip the fluid radially outwardly, and flared fluid-directing means for directing the fluid in a direction first largely radial and then curved toward an axial direction in its passage through the bladed portion of the fan.

CHARLES F. JEIVKINS. RAWDON E. RAMBO.

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