US1030561A - Fan. - Google Patents

Description

E. B. BLACKMER & E. W. JOHNSON.

FAN.

APPLIOATIQN FILED SEPT. 2, 1910.

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E. E. BLAOKMBR & E. W. JOHNSON.

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APPLICATION FILED s 1111111111 1,030,561 Patented June 25, 1912.

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ERNEST E. BLACKMER AND ERIC W. JOHNSON, 0F MONONGAI-IELA, PENNSYLVANIA.

FAN.

Specification of Letters Patent.

Patented June 25, 1912.

To all whom it may concern:

Be it known that we, ERNEST E. BLACK- MER and E1110 V. JoHNsoN, residents of Monongahela city, in the county of Washington and State of Pennsylvania, have invented a new and useful Improvement in Fans; and we do hereby declare the following to be a full, clear, and exact description thereof.

Our invention relates to fans and particularly to the so-called centrifugal type. The

fan embodying our invention, however, does not act solely 011 the centrifugal principle, but very largely by propulsion also, which is true to a lesser extent of a number of fans at present in use.

The object of our invention is to increase the attainable running efficiency of a fan unit, including both the mechanical and manometrioal efiiciency.

By our invention we have constructed a fan which has a manometrical efficiency of nearly twice the manometrical efliciency of the Capell fan, which is in our opinion one of the best fans at present in use.

Hitherto the improvements in the blade or vane construction and arrangement of centrifugal fans have been along the lines of changes in the curvature and length of the blades and the angle at which each blade is set from a radius to the center of the fan. Thus, in the Guibal ventilator, the blades are curved backwardly in the direction of rotation from the radii at their inner edge on the throat of the fan, and then curved forwardly toward the circumference of the fan proper, so as to be practically radial thereat. In the only recognized text books or treatises on the subject of fans which receive the air through an intake disposed in the side of the casing and eject it circumferentially, or vice versa, this construction has received very favorable comment. In another type of fan later developed, namely, the Capell ventilator, the casing construction was improved by allowing a crescent shaped space entirely around the fan proper and widening toward the chimney or stack. In this type of ventilator secondary or auxiliary blades are provided attached on the rear side of the main blades and designed to prevent eddy currents passing across the end of the main blades from returning into the fan and thereby decreasing its efficiency both as to the volume of air moved and pressure of air delivered. In the theoretical treatment of this subject, it has been generally accepted that the outlet end of the channels leading outwardly from the throat between the blades should be as great or greater in cross section than the inlet end. The reasons given therefor do not admit of exposition here in detail, although in general we understand it has been believed that a larger orifice at the outlet than at the throat was desirable as emitting air at a less pressure in striking the outside air. It will be understood that in fans of this type, as well as in disk fans, which act entirely by propulsion or positive displacement of the air,

the fans are in general reversible so that where used in ventilating mines or the like, they can act either as blowers or as suction machines, being respectively behind or ahead of the air current produced, although the approved practice is to change the exhaust or stack connection from the atmosphere to the mine outlet if it is desired to change from an exhausting to a blowing operation.

In the device of our invention the fan is designed to act simply in the direction described, or outwardly, and will not act at all if reversed. That is, our fan has a high efficiency if run in the proper direction, but will not displace air backwardly through the intake. We regard this feature as a strong indication that our invention embodies correct principles of construction.

The new features of our invention which act most elfectively when combined, are several. We provide a series of channels having inlet or throat orifices of a larger cross section (measured either approximately normal to the fans or blades or along the peripheries of the throat and circumference respectively) than the delivery orifices at the circumference. The blades are preferably curved backwardly at the throat so that the forward blade of one channel forms an acute angle with the rearward blade of the next channel. A vane of wedge shape at its inner angle and general triangular cross section is thereby provided between each two channels. Both walls of the vane are arranged at backward angles in the direction of rotation from radii to the fan center, sothat the inner angles of the vanes in their movement constantly present acute angles or wedges to the outwardly traveling air, thereby aiding in lts dlsplacement. To this feature alone we attribute increased efliciency in propelling the air. The vanes therefore are not mere blades, but have a considerable outward or circumferential dimension so that the circumference or barrel, 2'. e., the outsidecylinder of the fan proper is a series of are shaped blades or walls instead of being substan tially open and interrupted only by the outer edges of the blades. At the forward side of each delivery orifice we provide a rearwardly directed but forwardly curved blade for the purpose of propelling the air current produced positively and consequently. producing a vacuum behind each' blade and in the region of the increasedv pressure produced by the reduced size of the said orifices.

In the drawings illustrating our invention, Figure 1 is alongitudinal cross section of a fan unit. Fig. 2 is a transverse cross section through the axis or shaft of the fan on the line 22 Fig. 1. Fig. 3 is an en larged detail fragmental cross section in the plane of Fig. 1; and Fig. 41 is a detail perspective view of the fan proper.

The fan or ventilator unit 1 is provided with a suitable casing 2 of any approved type, the fan proper 3 being carried on the shaft 4 as by the bracket 5 keyed to the shaft A at 6 and bolted at 7 to the circular side wall 8 of the fan. The opposite circular side wall 9 is provided with the intake orifice 10 of suitable size. The size of the intake 10 may be varied as desired and found most eficient by calculation and ex-' periment. The fan 3 is mounted in the easmg 2 so that the blades or propellers 11 just clear the angle 12 of such casing, and the are or crescent shaped channel 13 is provided therein around the fan and leading to the chimney or stack 14:, as shown. The

vanes 15 comprising the rear blade 16, forward blade 17, and circumferential walls 18 are set up in any desired fashion. As illustrated the outer walls 18 are attached to the circular side walls 8 and 9 by the screws 10 and carry the integral propeller plates 11. The blades 16 and 17 are shown attached to.

the walls 8 and 9 by the angle bars 16 17 respectively, riveted thereto.

method of construction may be followed within the spirit of my invention, it being in no way essential that the vane should be formed hollow as illustrated, as the separated channels and arc shaped outer walls may be obtained in various ways.

As illustrated in Figs. 1 and 2, when the fan is revolved by the shaft 4 the incoming air passes through the intake and thence in a course perpendicular thereto as shown by the arrows outwardly toward the circumference of the fan.. At the start of opera- "tion the displacement of air is no doubt It will be understood, however, that any convenient caused largely by centrifugal action and the air passes thereby through thechannels 20. The wedge shaped vanes 15, however, have their inward edges 21 traveling through said air, their inward ends 21 forming an The blades erably of the curved form shown, so that the inner end of each blade or wall 17 forms an acute wedging angle with the inner end of the next succeeding wall 16, the wall 16 being arranged opposite to the wall 17 at any desired curve so long as the narrower cross section of the channels 20 at their outer than at theirin'ner ends is preserved. The propellers or outwardly projecting blades 11 tend to accelerate the currentof air in the channel 13 around the fan and aid in its propulsion to and through the stack 14:. Each blade 11 also sets up a vacuum or region of reduced pressure 6 immediately behind it, so that an additional impulse or pull is imparted to the air current passing through each channel 22. By this means we positively prevent eddy currents and greatly increase the efficiency of the fan, as

any stoppage of the air in each channel due to increased pressure in the region a is prevented and the said pressure acts positively to emit the air at an increased velocity due to the region of reducedpressure 6 adjacent thereto. Any tendency to eddy currents, as

indicated by the arrows r to enter the fan in 'a backward direction is prevented by the higher water gage or pressure in the region I) and outer wall 18 of the vane 15 next in direction of rotation, and by the increased pressure of the air in the regionc immediately in front of the next succeeding-propeller blade 11. The propeller blades 11 therefore act to continuously produce a stream or current of fast moving'air at successively greater distances from the circumference of the fan. The obvious efiect of this, where the fan is employed in a casing such as that illustrated, is to provide a current or stream of air in the direction of rotation of the fan and probably having a tendency to increased pressure near the circumference or wall of said casing.

We have observed by repeated tests that not only does the air current passing through V the stack 14 have a much greater pressure in given -d1rections than the most efficient fan obtainable of any other type, but that its pressure is evenly distributed across the outlet i i of the stack. Thus it is just as high when the fan is running at a high rate in the region m as in the region n, as illustrated in Fig. 1.

While we have not reduced the operation on construction of the fan of our invention to theoretical conclusions or formulas, we regard its construction as essentially novel.

lVhat we claim as new is:

1. A fan having vanes provided with outer walls forming the outer circumferential wall of the fan proper, forward blades inclined backwardly from radii to the fan center and each joining the forward end of one of said outer walls at an obtuse angle to form the rear wall of each outlet orifice, and propeller blades projecting outwardly from said outer wall forward of said outlet orifices.

2. A fan having vanes provided with outer walls forming the outer circumferential wall of the fan proper, forward blades inclined backwardly from radii to the fan center and each joining the forward end of one of said outer walls at an obtuse angle to form the rear wall of each outlet orifice, and a propeller blade projecting outwardly from said outer wall forward of said outlet orifice, the inner ends of said forward blades being separated by throat orifices larger in cross section than said outlet orifices.

3. A fan having vanes provided with separated outer walls forming the interrupted circumferential wall of the fan proper, blades joining said outer walls at their ends and forming air channels having their throat orifices between the inner ends of said blades of greater cross section than their outlet orifices between the ends of said outer walls, and an outwardly projecting propeller blade arranged at the forward side of each outlet orifice, the outer ends of said blades being inclined backwardly from radii to the fan center, and the inner ends being separated by spaces forming throat orifices greater in cross section than said outlet orifices.

4. A fan having vanes of substantially triangular shape and provided with outer walls forming collectively the interrupted circumferential wall of the fan proper and forward and rear blades joining the forward and rear ends respectively of each of said outer walls and meeting at an acute throat angle, said forward blades being inclined backwardly from radii to the fan center and meeting said outer walls at an obtuse angle, said forward and rear blades forming backwardly inclined air channels having outlet orifices between the outer ends of said blades, and forwardly curved propeller blades extending outwardly from said outer walls at the forward sides of said outlet orifices.

In testimony whereof we, the said ERNEs'r E. BLAOKMER and ERIC W. JOHNSON, have hereunto set our hands.

ERNEST E. BLACKMER. ERIC W. JOHNSON. Witnesses:

NETTIE V. BLACKMER, WALBORG JOHNSON.

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

Washington, D; G.

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