US2032610A - Fan - Google Patents

Description

March 3, 1936.

O. L. GIBBS FAN Filed Sept. 17, `-1934 2 Sheets-Sheet 2.

ATTRNEY' Patented Mar. 3, 1936 UNITED STATES FAN Orma L. Gibbs, Kansas City, Mo., assignor of onehalf to Eugene B. Berkowitz, Kansas City, Mo.

Application September 4 Claims.

My invention relates to fans, and has for its principal object to provide for more eicient movement of air with a minimum amount of power with a given size fan.

Other important features are to provide a fan structure which effects delivery of air at high pressures near the axis thereof, to reduce hum caused by the revolving blades, and to effect movement of the air in such a manner to eliminate back fiow of air currents between the fan blades.

In accomplishing these and other objects o1' the invention, I have provided improved details of structure, the preferred forms of which are illus,- trated in the accompanying drawings, wherein:

Fig. 1 is a perspective view of an ordinary electric fan equipped with a fan rotor embodying the features of the present invention.

Fig. 2 is an enlarged side elevational view of the fan rotor.

Fig. 3 is an enlarged detail view of the center of the fan rotor. particularly illustrating the hub construction. y

Fig. 4 is a cross section tnrough one of the blades on the line 4 4, Fig. 3.

Fig. 5 is a cross section through the hub of the fan on the line 5-5, Fig. 3. L

Fig. 6 is a detail perspective view of the fan rotor illustrating the movement of the air currents generated by the fan.

Fig. 7 is a perspective view of a two blade fan embodying the features of the invention.

Fig. 8 is a perspective view of a three blade fan.

Fig. 9 is Ia front elevational view of a six blade fan. Y

Referring more in detail to the drawings:

I designates an electric motor having its armature shaft 2 equipped with a blade fan 3 constructed in accordance with4 my invention. The fan 3 is best illustrated in Fig. 2 and includes a hub l having blades 5, 6, 1 and 9 extending radially therefrom and arranged in symmetrical pairs on the opposite sides thereof to provide a balanced construction.

The blades 6 and 8 are preferably of shorter length than the blades 5 and 1 so that the tips 9 thereof revolve in a circular plane of different diameter than the ,tips I0 of the blades 5 and -'I, thereby reducing the frequency at which the blades of one pair pass a given point.

This construction considerably reduces hum generated by the rotating blades and need not limit the capacity of the fan because the shorter blades can be constructed of greater width and can be provided with a greater angular pitch 17, 1.934, serial No. 744,333 (Cl. 23o-261) p relative to the axis of the hub than the longer blades, so that they will move substantially the same amount of air as the longer pair of blades. Increasing the width of the shorter blades also does not affect the powerrequired in rotating the fan due to their shorter leverage.

The blades may be given any suitable angle of pitch depending upon the velocity of air desired and the purpose for which the fan is to be employed. The relative pitch and width of the blades may also be varied in wide limits. However, the relation of the side edges I I and I 2 thereof bear an important relation to the hub of the fan, as now to be described.

'I'he hub 4 is provided with an axial bore I3 having its end terminating short of the front face of the hub, as clearly shown in Fig. 5, to ymount the fan on the armature shaft 2.

The fan is secured by a set screw I4 that is threaded in an opening i5 extending in the hub at right angles to the axis of the bore I3, so that the inner end I6 of the set screw clampingly engages the armature shaft of the motor.

The hub 4 is provided with air propelling faces I1, I8, I9 and 20 forming continuations of the propelling surfaces of the fan blades, butr are arranged at a. steeper pitch than the pitch of the blades to effect spiral movement of the air deiiected therefrom about the axis of the fan, as illustrated at 2 l, Fig. 6, so that air drawn in between the blades near the hub is caused to move in a spiral path in a cone formation and at high velocity toward the axis of rotation to merge with the substantially parallel streams of air deflected from the body portion of the blades as indicated by the arrows 22 at a point spaced from the front face of the fan.

'This is a most important feature of the present invention, as the spiral movement of the air at high velocity not only adds to the effective movement of the air, but it prevents return of the air back through the blades of the fan, as is the case in conventional fan design.

Attention is also directed to the fact that tests made with my improved fan show that air is drawn inwardly from the tips of the blade, as shown in Fig. 6, to lend to the effectiveness and efficiency of the fan.

In forming the pitch of the air propelling face of the hub, the front side edges of the fan blades extend through a common plane and terminate in said plane at a common point on the center therefore, extremely wide adjacent the hub and have greater propelling surfaces at this point to enhance the emciency of operation. A

Also, by increasing the effective pitch at the hub, this portion of the fan is caused to perform useful work and at the same time prevents the air moved by the outer ends of the blades from moving inwardly toward the axis of the fan,

thereby maintaining an air stream of substantially the same diameter as that of the fan. This is an important feature, particularly Where the fan is varranged to discharge air through any opening or into an air duct.

In Fig. 7 is illustrated a modified form of fan employing two blades, wherein the edge 23 of one blade extends across the axis of rotation vinto contiguity with the corresponding edge 24 of the' other blade to give substantially the same effect as the construction shown in the forms in Figs. 2 to 6, inclusive.

InFig. 8 is shown a modified form of fan'employing three blades, the trailing edges 26 of the fan blades terminating in the center of the axis of rotation, as at 2l, in the same manner asshown in the four blade type of fan.

Fig. 9 shows a still further modified form of the invention wherein six blades are employed with alternate blades 28, 29 and 30 being of shorter length than the other blades 3 I, 32 and 33 similar to the four blade type, previously described. The trailing edges of the blades each extend across the axis of rotation substantially in the same `manner as the construction shown inFig. 7.

While I have described the fan as being associated"with the movement of air streams, it is obvious that the fan may be used for moving vany form of gaseous fluid without departing from the spirit of theinvention.

It is also apparent that fans embodying the same features of the invention may be utilized -for drawing air from a source of supply by extending the opposite edges thereof` across the axis of rotation and forming the socket in the hub on the side opposite to that shown in Fig. 5.

From the foregoing, it is apparent that I have provided a fan construction which delivers air athigh pressures at thercenter thereof and that by constructing alternate blades of different length, the frequency at which the blades pass a outer tips of the blades to said points of tenni-l nation in the axis of rotation.

2. In a fan of the character described a plurality of blades positioned at an angle to an axis l of rotation with the side edge of one blade extending contiguously of a plane extending at right angles to the axis of rotation and termi-vv nating in said plane at a common junction with the ,same relative side edge of an alternate blade, said blades having propelling surfaces extending continuously from outer tips of the blades to said common junction.

3. A fan of the character described including a plurality of blades, and a hub supporting the blades having propelling surfaces terminating in radial edges extending contiguously of a common o plane and passing through a common point on the axis of the blades and in said plane, said hub having propelling surfaces extending to said common point and having a greater pitch angle than that of the blades.

4. In a fan of the character described, a plurality of blades arranged symmetrically-about an axis of rotation and 'having radial edges thereof extending contiguously of a'common plane at right angles to said axis of rotation and lterminating in a common point at the axis of rotation .and in said pla-ne and having opposite radial edges 'converging toward said plane, said blades having propelling surfaces extending continuously from outer tips of the blades to Said point of termination in the axis of rotation.

QRMA L. GIBBS.

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