US2176324A - Segregated pressure fan - Google Patents

Description

Oct. 17, 1939. w. H. BRETZLAFF ET AL 2,176,324

SEGREGATED PRES SURE FAN Filed Dec. 28, 1936 3 sheets-sheet 1 f f w/ w n m? m W n 56 A HP rs Z MW 1939- w. H. BRETZLAFF ET AL 2,175,324

SEGREGATED PRESSURE FAN Filed Dec. 28, 1956 3 Sheets-Sheet 2 INVENTOR. Vl a/ir firefy/a/f BY Czar/e6 P 6 /7/7765 ATTORNEY.

1939- w. H. BRETZLAFF ET AL 2,176,324

SEGREGATED PRESSURE FAN Filed Dec. 28, 1936 3 Sheets-Sheet 3 1 N VENTOR. w/f er MZ/eZy/aff ATTORNEY.

Patented Oct. 17, 1939 SEGREGATED PRESSURE FAN Walter H. Bretzlaif, Detroit, Mich., and Charles P. Grimes, Syracuse, N. Y.

Application December 28, 1936, Serial No. 117,748

3 Claims.

Our invention pertains to fans of improved 'efficiency and utility, and more particularly to fans comprising means for segregating the air from the different pressure areas of the fan.

In previously known fans satisfactory operating efficiencies have not been obtained, and (Hillculty has been experienced because of the different air pressures set up by the fan in adjacent areas whereby the energy expended upon the air by the fan was largely dissipated in churning the air and causing currents of air to flow in and out of the path of the fan. More particularly such difiiculties have been very serious when'projecting the air thru a conduit to a remote location from the fan, and previously when fans have. been utilized with conduits, 10w eificiency and unsatisfactory operating characteristics have resulted. Also, it has previously been necessary to provide individual fans to supply air separately to different locations for different pressure and velocity conditions.

It is an object of our invention to provide a fan of improved efficiency.

It is also an object of our invention to provide a fan comprising means for segregating the air projected from the different pressure areas of the fan whereby separated air streams may be supplied to separate points for use under different pressure and velocity conditions.

It is also a further object of our invention to provide a segregated pressure air source comprising a combination of an air impeller, and an air collecting plenum chamber, properly disposed in a high pressure portion of the air stream for receiving and segregating the air projected from that portion of the impeller whereby it may be passed through an associated conduit for supplying air under higher pressure or higher velocity conditions, and the 'air projected from the y other portions of the fan may be utilized at a different location under diiferent velocity and air conditions.

Another object of our invention is to provide a segregated pressure air source comprising the 45 combination of a disk or propeller type fan, an .open sided pressure plenum chamber of annular conformation disposed adjacent the high velocity portions of the fan in the high pressure area of the air stream, and a deflecting plate disposed at the side of the plenum chamber on the outer wall thereof for deflecting the projected air into the pressure plenum chamber toward the axis of the fan, and for shutting off back eddies from the surrounding air.

1 A further object of our invention is to provide the combination of a centrifugal type of fan with a pressure plenum chamber of annular conformation surrounding the outer extremities of the fan and comprising an open air receiving port extending around the inside portion of the plenum chamber and so disposed relative to the fan that the high pressure air is received therefrom and additional conduit means inclosing the low pressure air therefrom in segregated relation.

The features that we consider characteristic of our invention are set forth particularly in the appended claims. The invention itself, however, both as to its organization and its method of operation, together with additional objects and advantages thereof will best be understood from the following description, when read in connection with the accompanying drawings, in which:

Fig. l is a plan view of an embodiment of the improved unit, a portion being sectioned and broken away to more clearly illustrate the construction and arrangement of the unit and its associated elements;

Fig. 2 is a cross sectional view taken on line 22 thereof;

Fig. 3 is a view showing the pressure curve of a propeller type fan drawn to scale and associated with one of the propeller blades for illustrating the principle of operation of our invention;

Fig. 4 is a plan view partially sectioned and broken away showing another embodiment of our invention as applied to a combined centrifugal type and propeller type of fan;

Fig. 5 is a cross sectional view on line 5-5 thereof; and

Fig. 6 is an enlarged sectional view taken on line 66 of Fig. 4.

Referring more specifically to Figs. 1 and 2 of the drawings, we have illustratively disclosed our invention comprising a segregated air pressure source. In this embodiment of our invention, the air deflecting fan comprises radially projecting blades 3 which are secured to a hub member 5 which may be provided with a laterally projecting flange '1 on which the blades are secured in any suitable manner, as by rivet-s 9. It will be understood that the fan may be a propeller or disk type fan of any well known construction. By disk type is meant any propeller fan whether made of a unitary metallic disk or otherwise. The fan is mounted upon the extended shaft ll of a suitable motive means, such as an electric motor l3, and it is rigidly secured thereon as by means of a screw l5 for rotation clockwise as viewed in Fig. 1.

Disposed adjacent the high velocity sections of the blades 3 of the fan we provide one or more plenum chambers of annular conformation. As will be understood, we may use any portion, or portions, of these annuli as desired, either for one outlet or for many separate outlets. For this purpose we preferably construct a pressure plenum chamber or air collector ring l7 comprising an outer annular side wall IQ of large diameter for surrounding in spaced relation an inner side wall 2| for defining the plenum chamber space I! therebetween. The side walls i9 and 2! of the plenum chamber are provided with a closed end portion 23 by which they are secured in spaced relation and the chamber is thereby closed at one end.

For supporting the motor l3, three radially projected arms 25 are provided in equal spaced relation, and they project inwardly from the inner wall M in inclined relation toward the common axis of the concentric chamber walls.

The inner end of each arm 25 is provided with a curved finger 21 of suitable conformation for snugly gripping one end of the outer shell of the motor. The motor gripping fingers 2'! are preferably each covered by a rubber sleeve 29 whereby the motor is mounted in an insulated cushioned relation in the axis of the pressure plenum chamber.

The other end of the fan motor is supported by means of a spider 3| which is provided with three arms 33 which extend radially therefrom for abutting the closed end 23 of the plenum chamber. A motor receiving socket 35 is provided in the center of the spider for receiving the adjacent end of the motor shell, which may be cushioned snugly therein by an annular cushion 31. For rigidly supporting the outer ends of the spider arms 33 in abutting engagement upon the closed wall 23 of the plenum chamber suitable spaced apertures 39 are provided therein and internally threaded for receiving screws 4!. A suitable shim 43 is preferably provided between the end of each spider arm 33 and the closed end of the pressure plenum chamber upon which the spider arm is snugly clamped by means of the screw 4|.

The outer wall H! of the plenum chamber is elongated to completely surround the outer extremities of the fan blades 3 in enclosing relation. Upon the extended edge of the annular side wall I9 is provided a flange 45 for receiving the edge of an annular shell 41 which is disposed snugly thereon and secured by screws 49 which are turned snugly into suitably threaded apertures provided in the flange.

The shell 41 encloses any open material or member through which the air is to be drawn and which provides a less than atmospheric pressure in the entry plenum chamber, which is enclosed by the side Wall i9. For this purpose a filtering cartridge of any suitable construction may be installed in an inner side wall 5| with closures 53,'of disclike conformation, of wire screen or other suitable open work construction for holding the filter material 55 in the filter cartridge while permitting the passage of air as it is drawn therethru by the fan into the suction plenum chamber adjacent the intake side of the fan where a pressure less than atmospheric is obtained.

Inaccordance with our invention we provide an annular deflecting plate 56 which is secured in the open end or inlet of the plenum chamber IT. The deflecting plate 56 is disposed around the outer portion of the air receivingport of the air collecting plenum chamber, and is of a suitable curved conformation for enclosing the high velocity sections of the fan blades 3 as closely as possible in practical construction. The inwardly extended portion of the deflecting plate 56 is provided with a reversely curved edge 51. The space between the innermost edge of the defiecting plate and the inner wall 2| of the plenum chamber is made as narrow as it can be used and. take off the volume of air desired. The radial location of this annular opening, and the width thereof, can be determined from the test data plotted in Fig. 3, for this set up.

The annular deflecting plate 56 is so shaped and located as to guard the high velocity slip stream of the fan against interfering and deflecting currents that naturally tend to destroy the segregated high velocity areas that it is an object of our invention to preserve and utilize.

The annular deflecting plate 56 serves to defiect the high pressure air projected fromthe fan and also to shut off the back eddies caused by negative pressures which are induced by the outer extremities of the fan blades thus providing a segregated volume of high pressure air in the plenum chamber and greatly improving the desired operation of the fan. For leading the air from the air collector ring or plenum chamber H, a conduit 59 is provided in the outer side wall I9 where it connects from an outlet port 6|. The conduit 59 is secured to the outer wall l9 of the plenum chamber around the edges of the outlet 6| in any suitable manner, as by being welded for example, and it preferably extends tangentially therefrom. The outlet conduit is thus disposed in a proper direction for efficiently utilizing both the rotative velocity head and the pressure head of the air which is thrown from the fan rotating clockwise, as shown in Fig. 1. The plenum chamber may also supply another outlet conduit 60, of which any desired number may be provided. The conduit 59 is made'of suitable cross section for connection with standard flues and conduits to carry the volume of air which is to be delivered under suitable pressure and velocity conditions, in accordance with the usual ventilating practice.

By this arrangement a single fan can be efiiciently utilized both for delivering from the inner portions of the blade a large volume of low pressure air, which is delivered in a broadly diverging stream and may be utilized in the vicinity of, or directly in front of, the fan for example, and for delivering a substantial volume of high pressure air, which is delivered thru the conduit 59 to be delivered in segregated relation for use under diiferent pressure and velocity conditions.

In operation, greatly improved eificiencies are obtained from our segregated pressure fan and a single fan can be utilized for supplying air under different pressure and velocity to different locations, thus obviating the necessity of providing a different fan for each difierent purpose. The efficient delivery of air through a conduit, is also rendered possible by means of our improved fan assembly.

The principle of operation of our segregated pressure fan will be readily understood by reference to Fig. 3 of the drawings where an air velocity curve is plotted in projected relation to a blade 6| of a propeller type fan. The abscissae of the curve are plotted to the same scale as the fan blade and represent the corresponding points adjacent the fan blade where the velocity of the air stream was measured.

The measurements for plotting the ordinates of the curve shown were obtained by means of an impact tube 63, which was connected through a flexible rubber tube 65 with a remotely disposed manometer tube 61, of conventional construction, comprising a scale 69 of one leg for providing visual manifestations corresponding to the pressures induced in the impact tube 63 by the air stream from the fan. To obtain the data for the curve shown, the end of the impact tube 63 was spaced one-half inch from the plane of rotation of the propeller and moved along a line parallel thereto as indicated.

Our data show a difierent curve for each range of spacings at intervals of one-half inch further away from, or nearer to, the trailing edge of the blade. family of curves, best illustrated by the one-half inch series here shown. Fig. 3 shows part of an interesting study of air flow through a fan mounted in an opening in wooden bafile 10, as shown. I

The attached graph shows t l 1 e values of velocity taken as a function of \/h. The symbol h represents the height of the water column and the values of h were read from the manometer in inches of water. Those values above the axis OA-BC-D are positive and indicate air was flowing toward the impact tube as expected.

The values below the axis OA--B-C-D are negative and indicate air was flowing away from p velocity in such close proximity, to the highest velocity of out going air causing considerable interference therewith and entering the outlet side of the fan in the high velocity terminal portions of the blades.

Although the air velocity curves obtained from difierent fans varied somewhat, that same difficulty was found in the operation of all proarated streams R airwhich may be separately I transmitted and utilized under different pressure and velocity conditions, at remotely spaced locations, for which purpose any desired number of plenum chambers may be utilized.

By similar research on the centrifugal types of fans, we have discovered that similar adverse conditions also detrimentally affect. their operating characteristics and the efiicient operating principle of our invention may also be applied to fans of the radial or centrifugal type. It is also possible to provide our centrifugal type of segregated pressure fan in a combined relation with a fan of propeller or disc type for simultaneously delivering a large volume of low pressure air for application in the vicinity of the unit. The term air moving wheel wherever used designates a fan of either type. Such an embodiment. or our invention is illustratively disclosed in Figures 4, ,5 and 6 and is claimed in our co- When plotted they make a pending patent application Serial No. 298,790 filed August '7, 1939.

Such a fan is conveniently constructed from a dished sheet metal member 10, having cylindrical or conical side walls, and from which portions of the closed end wall are displaced to provide the radially extended propeller blades 13 which may be thereafter twisted to proper angular positions and suitably curved. By suitably slitting the conical or cylindrical side Walls of the fan dish 19, blades H may be turned to provide centrifugal or turbine blades, as will be readily understood. A circumferential rim M is left uncut for connecting between the outer ends of the propeller blades I3 and the lower ends of the turbine blades H. The outer or open edge 11 of the sheet metal fan disc 10 are preferably turned outwardly around a reinforcing rod 19 whereby a stiff reinforced rim is provided. At their innermost ends the propeller type blades 13 are secured as by rivets 8| for rigid connection to flange 83 upon a hub 85. The hub 85 is suitably apertured for axial mounting upon the extended shaft 86 of a suitable motor 81 by which the fan is driven.

Surrounding and enclosing the centrifugal blades H of the cylindrical fan, we provide a scroll chamber 89 enclosed by walls 9| for re- 'ceiving the air projected therefrom, and converting the velocity head thereof into a suitable in the direction of rotation at an angle of divergence which is preferably about 12 degrees, in accordance with the usual practice.

In practice we have found that fans of the centrifugal type also project the air into different pressure areas spaced axially along the outer edges of the fan blades, and in accordance with the principle of our invention, a pressure plenum chamber 93 is provided which is enclosed by suitable spaced annular side walls 95, which pass through an intermediate portion of the scroll chamber. The side walls 95 are joined by an external wall 9'! and the air collector chamber opens inwardly adjacent the fan blades H.

The side walls 95 of the plenum chamber 93 are suitably spaced to provide an open air receiving port adjacent the outer tips of the fan elements H, of a proper dimension for receiving and segregating the higher pressure air therefrom. The outer peripheral wall 91 of the plenum chamber is also of angularly diverging conformation to define a scroll for receiving the high pressure air, which is thus converted from a velocity head to a pressure head. The inwardly directed edges of the plenum side walls 95 are tapered to provide sharp edged fins 96 offeringminimum resistance to'the air stream. The scroll chambers 89 and 93 may start from different circumferential points around the fan and may be made with different angles of divergence as desired.

Connecting from the scroll chamber 89, a conduit 99 is provided which leads tangentially therefrom for leading off the trapped air. As shown by Fig. 5, the cross section of the scroll chamber 89 is of substantially elongated rectangular conformation at the point where the conduit 99 connects, but the conduit is preferably suitably tapered to provide a proper cross section for connection with the standard conduits generally used in accordance with the usual practice in the ill) in Fig. 6, the chamber 93 is radially extended to the greatest extent at the point of connection into conduit llll.

For supporting the fan motor 81, bracket arms I03 extend in spaced apart relation from the side Wall of the scroll chamber 89, and from each of the bracket arms I03 a motor supporting arm W5 projects radially toward the axis of the fan. For supporting the shell of the motor, fingers it! of suitable curvature are provided on the inner ends of the arms I05. For holding the other end of the motor shell, it is nested in a socket ill in a spider N19. The spider has a cushion bed M3 for the end of the motor and radially extending arms H4, which are secured by bolts I I5 to the outer ends of the brackets 13. The fan is thus supported in cushioned relation from the frame and housing of the air impelling unit. A flange Ill extends axially from the inlet end of the fan scroll St for receiving a sleeve H9 which holds a shell EN. The shell I21 contains any open member or material l23 through which it is desired to draw the air.

In operation the blades E3 of the propeller fan draw air in through the shell 12! and discharge a large volume for use adjacent the fan unit. Simultaneously, the centrifugal fan is also drawing air through the filter, and by a combination of fan forces, is throwing it through its blades H in a generally radial and tangential direction across most'of the blade width.

By searching with the impact tube, .the various areas of segregated pressures are found and recorded. The annular region of pressures desired is then housed over by a suitable scroll and may extend over a complete circumference, or any portion desired, and for one or more take-offs.

In this manner air is delivered by our fan unit for three difierent conditions of pressure and velocity. It will be readily understood that the principle of our invention may be applied and further extended by providing additional plenum chambers, suitably segregated and connecting from the fan. In the various modifications, the fan blades termed as propeller are either of curved sheet metal orof cast or forged air foil section, as will be readily understood.

Aside from the specific embodiments of the invention here described, it will be understood that numerous details of the construction may be altered or omitted without departing from the scope of the invention as disclosed and claimed, and that we do not desire to limit the invention to the exact constructions herein set forth.

We claim:

1. In combination in a segregated pressure air impeller unit for supplying high pressure air separated from a stream of air, a single inlet chamber of suitable cross section for supplying air to the unit, a disk type of fan having air deflecting propeller blades extending from its centerof rotation, means rotatably mounting said fan adjacent said inlet chamber for moving a unidirectional air stream therethrough, and the walls of said inlet chamber being of a suitable conformation for extending around the tips of said fan blades in closely enclosing relation beyond the outlet side of the fan and the edges thereof being turned in and back toward the fan to form an annular air collecting chamber to collect air from the high pressure portion of the air stream.

2. In combination in asegregated pressure air impeller unit for supplying high pressure air separated from a stream of air, a single inlet.

chamber for supplying air thereto, a rotatable disk type fan having air deflecting propeller blades extending from its axis of rotation for projecting a unidirectional air stream axially therethrough, an open sided air collecting plenum chamber of annular conformation disposed in the highpressure portion of the air stream adjacent the high velocity portion of the plane of rotation of said blades and having its open side adjacent thereto, and an annular air deflecting plate disposed in the open side of said plenum chamber and curved around the blade tips toward the outlet side fordeflecting air toward the inside of the chamber and shutting oil the currents of air which tend to enter the outlet side of the fan.

3. In combination in a segregated pressure air impeller unit for supplying high pressure air separated from a stream of air, a single inlet chamber for supplying air thereto, a rotatable disk type of fan having air deflecting propeller blades extending substantially radially from its axis of rotation for projecting an air stream axially therethrough, an open sided plenum chamber of annular conformation disposed in the high pressure portion of the air stream adjacent the high velocity portion of the rotatable fan blades and having its open side opening toward the fan, said plenum chamber comprising an outer wall extended axially for closely surrounding and enclosing the outer extremities of the fan blades, an annular air deflecting plate disposed in the open side of the said plenum chamber for defleeting air toward the inside of the chamber and shutting off the currents of air which tend to enter the outlet side of the fan.

WALTER H. BRETZLAF'F.

CHARLES P. GRIMES.

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