US2314696A - Air conditioning and circulating apparatus - Google Patents

Description

March 23, 1943. 1 M FumK 2,314,696

AIR CONDITIONING AND CIRCULATING AIPARA'IUS- 'Filed May '20, 19:59 9 sneetsAsheet 1 J. M. FUNK March 23, g

A AIR CONDITIONING AND CIRCULATING APPARATUS y Filed May 20, 1959 9 Sheets-Shes?. 2

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wmw ma@ vk March 23, 1943. J. M. FUNKY i 2,314,696

AIR CONDITIONING AND CIRCULATING APPARATUS Filed May 20, 1939 9 Sheets--SheetA 3 March 2.3, 1943 J. M. FUNK 2,314,696

AIR CONDITIONING AND CIRCULATING APPARATUS Filed May 20, 1959 9 Sheets-Sheet 4 March 23,L 1943.

J. M. FUNK .AAIR CONDITIONING AND CIRCULATING APPARATS Filed "May 2o, 1959 s sn March 23, 1943. J. M. FUNK 2,314,696

AIR CONDITIONING AND C-IRC-ULATING APPARATUS Filed May 20, 1939 9 Sheets-Shes?I 6 SS s N A, 1&1 /K/ Tdi. \\I\\ AIR CNDITIONING AND -CIRCULATING APPARATUS 9 Sheets-Sheet '7 Filed May 2o, 1939 March 23,1943.,v lM1-UNK Y y 2,314,696

AIR CONDITIONING AND CIRCULATING APPARATUS Patented Mar. 423A, 1943 James M. Funk; Ottawa, Ill., assigner to Lonergan Manufacturing Company, Albion, vMich., a corporation of Michigan Application May 20, 1939, Serial No. 274,793

6 Claims.

This invention relates to an air conditioning and circulating apparatus and has special reference to an apparatus for maintaining the air in` a room or other enclosure at a substantially uniform temperature for the purpose of comfort and for circulating the air in the room or other enclosure for the purpose of ventilation, both purposes being desirable for the healthy condition of the human body. v

In order to disclose intelligently the features of the present invention it is desirable to compare generally the functioning of the present apparatus with that which has gone on before. In the earliest times, caves or other enclosures inhabited by human beings were heated by open bontires, and later fireplaces. The open bonres and the fireplaces are most wasteful of heat because the air lwhich is heated by coming in contact with the open fire mixes with the smoke and gases therefrom and is moved upwardly therewith through the stack and is thereby lost to the room. 'I'he effective heat from the fireplace is caused by radiation, that is, the surfaces of bodies facing the fire being heated although the intervening air between the surfaces of the bodies and the fire in the fireplace Was cold. VThis may be likened to the heat which comesA from the sun. the space between the earth and the sun being cold but the portion of the earth facing the sun being warmed by its rays. Heat waves caused by radiation as from fireplaces pass through the air without heating it and have no heating effects until the waves are stopped by solid bodies. This is not a healthful type of .heat since the and the back is cold.

The aim 7`of modern heating apparatuses is toI heat the air which surrounds the human body and the air itself is not heated without first contacting the heat transfer surfaces. It therefore follows that the efciency of the heating apparatus is in direct proportion to the quantity of air circulated through the heater and the room or other enclosure in a given length of time. By enclosing the re in a fire pot to form a simple stove.y the efficiency of heat distribution was increased because the walls of the stove separated the air to be heated from the open fire. and the air thus heated was not mixed with the smoke and gases to move up the stack.v However. the only air which is heated is that which comes in direct contact with the heated surfaces of the stove by circulation which causes a large percentage of the heat in the room to come'from the stove by radiation. The heat near the stove is almost unbearable while but` a comparatively short distance away from the stove the air is cold. The floors are comparatively cold and the cellings comparatively hot.

Following the simple stove, a sheet metal shield was disposed in a-spac'ed relation with a heating The purpose of the shield was to stop means. radiant heat, the shield absorbing the radiant heat. The shield, in its spaced relation with the source of heat, provides a substantially greater heat transfer surface for the air to contact and circulate around. Such an apparatus produced a greater circulation than the simple stove and while it circulated more air and stopped a great deal o f radiant heat, it was comparatively wasteful of heat because the circulation of heated air therefrom was necessarily directed to the ceiling and such circulation produced a cold draft'0n the floor. f

In order to economize in heat and to secure a uniform temperature throughout the room or other enclosure, it has been found necessary to force the circulation of the air therein and at practical, economical, durable and whlchm'lll circulate conditioned air into every portion of the room or other enclosure and maintain a substan- The present air conditioning and circulating apparatus is of the forced air circulating type which may be disposed directly in a room or other' enclosure at any position therein consistent with y the arrangement of the fixtures thereof. In order for the apparatus to function successfully in the room to be heated it is desirable that the casing therefor be relatively'cool so that it will not be uncomfortable to the touch and the present apparatus vconforms to this requirement. Further, such an apparatus must be economical and operate efficiently With a motor of relatively low horse power. Since it is desirable, in the average room, to circulate a relatively great amount .of heated air per minute from the heating apparatus with a motor of relatively small horse power,` it was necessary to evolve an apparatus of maximum efficiency in the method of heating the air, in the design of the apparatus for so heating the air, and in the fan for moving the air in accordance with the apparatus and method.

Other objects and advantages of this invention will hereinafter be more particularly pointed out arrows showing th circulation of air through the apparatus when the air mover is not in operation and the air conditioning apparatus is operating as a radiant and gravity iiow convection heater; Fig. 3 is"`a-.plan sectional view taken on the line 3--3 of Fig. 1';"``2\ Fig. 4 is a side elevational view of Fig. 1 showing a portion of the outer casings thereof inv section as taken on the line 4--4 of Fig. 3, the circulation of air throughv the air conditioning and heating apparatus being indicated by directional arrows; Y

' Fig. 5 is a view similar to Fig. 1 of a modified form of air conditioning and circulating apparatus incorporating the features of this invention. the directional arrows indicating thev normal forced air circulation with the air mover in operation;

-Fig. 6 is a view similar to Fig. 1, the directional arrows showing the circulation of air when the air mover is in operation and the air conditioner is not in operation so that the apparatus operates as a circulatcr of cool air;

Fig. 7 is a fragmentary front elevational view of the air conditioning and circulating apparatus of Fig. 1 employing an air mover of a modified form incorporating the features of this inven- Fig. 8 is a. fragmentary plan sectional view taken on the line 8-8 of Fig. '7;

Fig. 9 is a fragmentary vertical sectional view v taken on the line 9 9l of Fig. '1;

Figli Fig. 12 is a central vertical sectional view taken on the line 12-:2 of Fie. 11 showing the motor and fan thereof in elevation:

Fig. 13 is a central vertical sectional view of a modified form of fan assemblv incorporating the features of this invention. showing the profile of the fan blades in rotation;

Fig. 14 is a front elevationalview of the fan propeller of Fig. 13:

Fig. 15 is a true side elevational view of Fig. 14:

Fig. 16 is a diagram upon which the geometric pitches of the fan propeller at various points in the blade radius are based;

Fig. 1'7 is anA end view of one of the blades of the fan of Fig. 14 from the leading edge to the trailing edge;

Fig. 18 is a sectional view of the blade of Fig'. 1 taken on the line |8--I 8 thereof Fig; 19 is a View similar to Fig. 18 taken on the line IQ-IS of Fig. 14;

Fig. 20 is a view similar to Fig. 18 taken on the 'line 2li- 20 of Fig. 14;

form of fan propeller incorporating the features of this invention;

Fig. 22 is a central vertical sectional view of the fan propeller of Fig. 21 showing the prole of the fan blades in rotation;

Fig. 23 is a true side elevational view of the fan propeller shown in Fig. 21;

Fig. 24 is a sectional view taken on the line 24-24 of Fig. 21;

Fig. 25 is an end view of one of the blades of the fan of Fig. 21 from the leading edge to the trailing edge;

Fig. 26 isy a sectional view taken on the lin 26-25 of Fig. 2l;

Fig. 27 is a sectional view taken on the line 21-21 of Fig. 21;

Fig. 28 is 'a sectional' view taken o n the line 26-28 of Fig. 21;

Fig. 29 is a front elevational view of the air propeller of Fig. 10; and

Fig. 30 is a side elevational view of Fig. 29.

Referring nowl to the drawings and more particularly to Figs. 1, 3 and 4 thereof, the air conditioning and circulating apparatus incorporating the features of this invention is shown as comprising a iirepot 30 into which liquid fuel is fed from a tank of fuel 3l, the fuel being fed through a duct 32 into a flow control mechanism 33 and therethrough to the ducts 34 and 34a connected to the flrepot. The flrepot 30 is enclosed by a casing 35 having an extension 35a at its upper end to form a combustion chamber above. the firepot. The upper end 35a of the casing is provided with a iiue 36 which latter is connected to a stack in order to permit the burned gases from the flrepot to escape. A door 31 is disposed in the upper end 35a of the casing for the firepot so that access may be had directly to the repot therethrough.

A shield 38 preferably entirely surrounds the casing 35 and the combustion chamber 35a, and

Fig. 21 is a front elevational view of a modified 75 is suitably spaced laterally therefrom, the shield being open at its upper end and being enclosed at its lower end by a pair -of pivotally mounted dempers 39 and 40 pivoted as shown at 40a. The

dempers 39 and 40 are preferably mounted centrally at thebottom of the apparatus to swing downwardly as shown more particularly in Fig. 2 by mechanical or automatic means as desired. In the operating condition of the apparatus at present described with reference to Figs. ,1, 3 and 4, the lower ends of the shield 38 and casing 35' are closed, the upper end of the shield 38 being open at all times in any condition of use of the apparatus. l

vThe casings 35 and 35a for the repot forming the combustion chamber thereof, together with the spaced shield 38, are suitably enclosed by a cabinet 4I, the walls of the cabinet being spaced from the shield.- The upper end of the cabinet is provided with a grille 42 and the side and front walls of the cabinet are provided with louvres 43 which are disposed at the lower end of the cabinet below the bottom of the casing 35 and the shield 38 aswell as below the dampers 39 and 40. The front of the cabinet is provided with a door 44 in registration with the door 3lfor access to the latter. i

As will hereinafter be more particularly disclosed, the air is circulated through the cabinet by action inducing a suction flow, the air mover unit 45 being preferably installed in the yfront of the cabinet at the lower end thereof. Openings 46 and 4l are provided .in -the cabinet 4l and the shield 38 respectively about the flue 36. With the dampers 89 and 40 closed and the air mover-in operation, there also being a re in the iirepot 30, the air mover unit 45, together with the normal gravity flow of air, causes a rising of a column of air along the outer surface of the cabinet indicated by the arrows 48. A second column of airis caused to rise on the inside'of the cabinet, the air column being indicated by the arrows 49. This latter mentioned column of air has intimate contact with the heat transfer walls of the cabinet and moves upwardly within the passage between the cabinet and shield. Similarly a column of air will rise along the outer wall` of the shield 38 in the passage between the cabinet and shield in the direction of the arrows 50 to have intimate contact with the heat transfer surfaces of the shield for conditioning the air. The air columns represented by the arrows -48, 49 and 50 are all influenced by gravity as well as by the action of the air mover.

The aforementioned columns of air 48, 49 and 50 augmented by air passing through the grille' 42 and indicated by the arrows 5|, form a downdraft column of airwholly influenced by the air mover 45 to have intimate contact as indicated by the arrows 52 and 53 on the inner side of the heat transfer surfaces of the shield 38 and the outer side of the casing 35a, respectively. The

downdraft columns of air 53 and 53 by reason of their intimate contact with the heat transfer surfaces of the inner wall of the shield and the outer wall of the casing from the upper ends thereof to the lower ends thereof are thus conditioned for exhaust through the fan opening. As shown more particularly in Fig. 4, a column of air indicated by the arrows 54 is drawnthrough the openings 46 and 41 communicating with the passages formed between the casing, shield and cabinet to have intimate contact with the heat transfer surfaces of the iiue 36, the column of air thus drawn through the openings merging with the air in the passages for subsequent exhaust by the air mover unit.

Inl the circulation of air through the air conditioning and circulating apparatus as above described, the air of lower temperature has contact first with the heat transfer surfaces of lower temperature and progressively the air comes in contact with heat transfer surfaces. of higher temperatures to obtain an evenly accelerated expansion of air thus reducing turbulence and strains on the materials ofthe apparatus as well as other features desirable in such devices toy be hereinafter more particularly pointed out.

Referring now more particularly to Fig. 2 of the drawings, when the temperature of the heater rises to a predetermined limit the air mover 45 may be cut off and the dampers 89 and 40 may be automatically or manually actuated to open the I lower ends of the shield 38 and casing 35 thus to admit airfrom the iioor to rise therethrough. The columns of air will rise in the spaces between the cabinet and the shield and between the shield and the casing in the manner indicated by the arrows and thus the forced air heater may be transformed into a radiation-convection heater.

The construction ofthe air conditioning and by the cone-'shaped hub which is larger cabinet and are diffused through the air mover at a point near the floor; f

With respect to the disclosure of Fig. 6, the construction thereof is identical to the construction disclosed in Figs. 1 to 4, inclusive, except that in this condition of use there is no fire in the firepot so that with the dampers 39 and 40 in a lowered position the cool air from the floor is drawnthrough the fan and circulated in the manner indicated by the arrows and the appa- .ratus is merely operated as a circulator of cool air. It is to be understood, of course, that the apparatus shown and described in Figs.. 1, 3 and 4, may operate as a circulator of cool air in the manner indicated by the directional arrows when there is no re in the repot.

Referring now more particularly to Figs. 7, 8 and 9. identically the same apparatus including the casing, shield, cabinet and the like is shown with the exception of the type of air mover unit employed. Instead of the air mover unit 45 as shown in the previously described gures, which construction will behereinafter more .particularly described, a fan comprising the usual fan blades 55 is mounted on a hollow hub structure 56 of substantially conical cross section, the hub in turn being mounted on a stud shaft '51 of a motor 58. The motor 58 is mounted within a funnel-shaped ring 58 or a ring which diverges in a direction away from the fan blades',the pelv ripheral surface of the motor preferably havingfins extending therefrom in a spaced relation j form a passage for air between the motor anA I, the divergingring 59. The diverging ring '59W forms a part of a diuser 60 comprising a plurality of outwardly diverging rings 6I and 62 which are held in a fixed spaced relation by fins An auxiliary propeller blade 64 is mounted on the outside end of the motor 58.

The rotation of the fan blades 55 causes air tobe passed outwardly between the diverging rings 59. 6I and 62 to spread in the directions shown by'the arrows 65. The propeller 64, however, causes a stream of air, indicated by the arrows 66,y to flow in the direction thereof around the motor and through openings in the conicalshaped hub structure. The conical hub member 5B being larger than the motor and being seated between the motor and the combustion chamber serves to shield the motor from the radiant heat waves therefrom. In this construction, therefore, the diffuser 60 andthe outwardlydiverging ringsthereof expand the outowing column of air in the direction of the arrows and the motor is cooled by an inowing column of air induced by the propeller 64,l the motor being protected from radiant heat from the combustion chamber than the motor and overlies av portionthereof.

'I'he air conditioning and heating apparatus dsc'losed in Fig. 10 is precisely the same as that disclosed in Figs. l, 3 and 4 of the drawings with the exception that a modified form of air diffuser 45a is shown. Further, the vertically extending type of louvres 43,' shown in the previously described embodiments, have had substituted therefor the substantially horizontally extending louvres 43a. The air flow through the passages between the cabinet, the shield and the casing around the flue is identically as described in tht` previous embodiments and the air mover 45a produces the same suction' draft` as recited with reference thereto.

Referring now more particularly to Figs. ll and l2, the .air mover assembly 45, shown in Figs.

1 to s of nie drawings, is dlsciod, the unit ecm- .prising a propeller il having preferably three blades and being formed preferably integrally with a hollow substantially cone-shaped hub 68. The hub 68 is provided with an axial aperture l! for receiving a stud shaft 1l extending from the motor 1l, the stud shaft extending from and being a part of the' rotor thereof. The open end hollow-cone-shaped hub is substantially greater in diameter than the outside diameter of the motorv and overlies a portion of the end thereof to act as a shield therefor from 4the radiant heat from the combustion chamber.

The motor JI is, in turn, secured within a diffuser 12, the motor preferably having fins 'I3 extending on the peripheral surface thereof outwardly therefrom to rest against a projectingV inner wall of the diuser and provide a. spaced relation between the diiuser and the motor. A fan guard 14 comprising a series of circumferentially and radially extending wires is secured to the outside of the heater cabinet 4l by means of screws 15, and the diffuser in turn is secured to the fan guard 13 by screws 16, there preferably air currents, thus obviating the necessity for the intermediate outwardly diverging diffusing ring ,'SI and the propeller also acts to obviate the necessity for the auxiliary propeller 64 of Figs. 8

and 9 to induce an air current for cooling the motor. The Iparticular propeller. construction employedfor this purpose will hereinafter be more particularly described.

The construction and operation ofthe air conditioning and 4circulating apparatus thus far dedowndraft and,l further, to exhaust the air from the apparatus. Other openings in the shield and cabinet near thellppcl rear thereof are of substantially greater diameter than the :due 36 to permit an inow of air to the passages to merge with the air therein. I

With reference to the embodiment of air mover shown in Figs. 7, 8 and 9, a diffuser is positioned immediately adjacent the downstream ortrailing edges oi.' the fan blades so asl to spread the air from the fan through a wide arc, the diffuser thus expanding the crosssectional area ofthe air stream producing a relatively low velocity Y* through the larger cross sectional area as com-S pared to the cross sectional area at thel blade and the consequent higher velocity thereat. The exhaust fan being of a tractor type in which the air is blown over the motor has a relatively large -diameter hub of hollow conical-shape embracing a portion of the motor to entirely shield the motor from the radiant heat from the combustion chamber, the motor being mounted in a ring in the center of the dlifuser which ring is larger 1n diameter than the motor. there being preferably radial fins'on the motor bridging the gap between the motor and the for permitting a' circulation of air therethrough. An auxiliary fan is mounted on the 'downstream end'of the motor shaft so as to blow outside air through the openings between the hnsV and aroimd the motor to cool the motor, the blast of air so generated to be blown forwardly to the front of the motor and under the conical-shapedl shielding hub to be moved by suction draft out from under the hub by ejector action of the air blast generated by the first-mentioned tractor type exhaust fan. Thus a circulation ofv air is produced to cool the motor.

As above mentioned, a fan of the tractor type is tioning as a forced air heater and the dampers' are opened when the heater is to function as a radiant and convection heater by gravity action circulation. Thse dampers may be operated either by mechanlcal or by manual means immediately upon the stopping or starting of the exhoust fan or when the temperature of the heater reached critical points.

An outer cabinet houses the shield and casing from the combustion chamber to provide another heat transfer surface with which the air to be conditioned and circulated contacts, the top of the cabinet having a grille and the bottom being provided with louvres or otherwise having openings to permit the inflow of air from the top and the bottom, the inflow of air from lthe bottom rising in the passage thus formed between the cabinet and shield to contact the heat transfer surfaces of the outer surface of the shield Aand the inner surface of the casing. This flow of air between the cabinet and the shield rises to the top of the cabinet or above the upper end of the shield to be moved by suction draft downwardly through the space formed between the casing for the combustion chamber and the inner wall. of the shield, the downflow of air contacting the heat transfer surface of the casing of the combustion chamber and the inner surface of the shield. Such a flow as is above described is both counterilow and tortuous path ilow, counterilow because the air of lowest temperature first contacts the heat transfer surfaces of lowest temperature and leaves the apparatus at the point vof contact with the heating surface of highest temperature, and tortuous path flow because the air entering the inlet openings of the cabinet at points remote from the discharge opening cannot pass directly to the exhaust opening but must first `move upwardly in the space between the cabinet and the shield and thence downwardly between the shield and the casing thus contacting all heat transfer surfaces of the apparatus.

From the above it will be apparent that the inner and4 outer heat transfer surfaces of both the cabinet and shield as well as the heat transfer surfacesrof the flue and of the casing for the combustion chamber are intimately contacted by the air moving through the spaces therebetween so as to most eificiently and effectively extract the heat from the surfaces thereof. The

Withln' the downstream area served.

spacing of the shield and cabinet from the combustion chamber casing allows the conversion of the radiant heat from the casing to heat which is conducted to the air contacting therewith. This movement of the paths of air, therefore, converts radiant heat from the combustion chamber to convection heat. 'I'he conversion of radiant heat to convection heat provides a form of preheating the air which subsequently is raised tol itsl ultimate temperature by the conduction .of heat from the walls of thecasing forming the combustion chamber. Therefore, thehottest airis brought `into contact with the hottest surfaces and the coolest air is brought into vcontact with the coolest surfaces prior thereto.

The use of a suction fan and its disposition a the lower front end of the cabinet is such as to most eihciently move the air through the appa--v ratus as determined by'dividing the horse power by the quantity of air moved'. The space bethe shield and the cabinet being of suicient cross sectional area relative to the fans capacity that the fan is operating under a minimum suction and exhausting against a negligible pressure.

As aresult of the arrangement of the elements of the apparatus, the kinetic energy is substantially all velocity pressure which is to say,'the air is moving with a minimum of turbulence. As

r.will hereinafter be more apparent, the velocity pitch vof the propeller or fan is very near the geometric pitch of the fan resulting in little turbulence being. created at the point of contact of the blades and the air so that all of the air coming to the working 'face of the fan is moved out throughv the orifice thereof at maximum velocity and has therefore a maximum of energy to penetrate, agitate, turbulate, and circulate the air Since all of the energy in the air stream at the trailing edges of the fan blades is velocity pressure and the direction of movement is helical as well as axial and, further,since the smallest contraction of the stream will appear about 1% of the fans diameter downstream from the leading edge of the fan blades-which is the point of contraction at which the air stream starts to expand, it follows that a diffusion element is most effective when situated at that point of contraction. Therefore, in the example shown in Figs. 7, 8 and 9, a diffuser made up'of diverging rings of' varying diameters is situated'in relation to the air stream so that the leading edges thereof are in the center of the vena contracta and the downstream edges in the expanda. The angles of the diverging rings are such as to produce the greatest deilection with least turbulence resulting, the air flow immediately upstream ofthe diverging rings,

being partly helical, gives the air the initial twist It is a characteristic of all pro- 1 peller fans to absorb least power per cubic foot of output when the fan is operating against no pressure. When the total energy of the fan has been converted to wholly staticv pressure', the power curve yhas reached the highest point. When the fan is exhausting into an enclosure such as a cabinet of the present type, a, pressure is built up therein so that the fan -is operating against static pressure. Some of the energy of the fan is thereby used to overcome pressure and the remaining energy is used to move the air through the heater. Since it is desirable to obtain the greatest quantity of air for the least power input it necessarily follows that the fan should not be subjected to pressure conditions.

A more eiiicient transfer of heat from surfaces to air is obtained in an air conditioning unit where a suction draft is employed than if the fan exhausts directly against the heat transfer surfaces. In the former instance, a. low pressure area is created adjacent to the leading edge of the fan and air tending to move lintovthis area of lower pressure from all directions' sets up a uniform air movement through all passages in the .apparatus insuring intimate contact between the air and all lheat transfer surfaces at comparatively low and equal velocity. `When the airis discharged against the heat transfer surfaces, the areaof contact of the vair column is not much greater than the cross sectional area of the disc swept out by the fan. A relatively small area of the'heat transfer surface4 is therefore subjected to a high velocity o f relatively cool air. I'he velocity energy in the flow of air is lost by impact with the'heat transfer surface, and the air is disbursed, losing its directional energy and seeking the paths of least resistance so that when there are paths of varying resistance, a great proportion of the air will-flow around and not into contact with the heat transfer surfaces. Since the hottest surfaces yproduce lthe greatest resistance to the iiow of air because of the expension of the, Aair caused by the heat, it follows that the least air will behad Where the greatest heat can be secured. Because of the non-uniformity of the air distribution, internal stresses and strains within the metallic structure are set up due to non-uniformity of expansion and contraction resulting in premature metallic fatigue and consequent short life thereof.

In the use of an exhaust type fan, the air will move in the general direction of. the fan, the

movementbeing relatively slow so as to remain mined for the purpose of producing a fluid veloc-A ity for which the quantity of air moved or the energy required to move the air is known. The dimensional line C of Figure 16 represents the distance traveled by the tip of the propeller in a given-length of time. In order to determine such distance the diameter of the propellers is multiplied b y pi, times the revolutions per minute. The dimensional line Pv, which shall hereinafter sometimes be referred to as velocity pitch, represents the axial velocity of the air moving through the propeller. The line Sv, the hypotenuse ofthe triangle dened by the dim linesCononeside andPoontheotherside,rep resents the path of the air or iluidvover the fan blade at the tip thereof and the angle formed by the intersection of the lines Svand the cosine indicated by the dimensional line C, shall be referred to asV the velocity pitch angle. The divisional points along the cosine or the base of the aforesaid triangle indicated by the dimensional line C indicated as R, JR, .6R and AR, are corresponding points in the blade radius indicated on Figures and 21 of the drawings and form pitch angles when intersected along the cosine by lines extended from the point Pg.

In Figure 16 the dimensional line Pg represents the geometric pitch ofthe fan at the tip of the blades thereof in order to secure the relative iluid velocity or the quantity indicated by the line' Pv since it is known that slippage of the -air occurs during the revoiution of the fan blades. The velocity pitch Pu and the geometric pitch Pg are arrived at as follows. Since the slip in terms of percent is equal to 4.7 minus the geometric pitch number of degrees, it fol- -lows that the geometric pitch at any point in the blade radius is 1 plus the slip in percent, times the height in velocity pitch.

The length of the blade in terms of degrees is arrived at as follows. By experiment it has been found that the peak of elciency of fan performance is secured when the projected area of the physical structure of the fan comprises about .6 of the area swept out. The total area ofy the blades thus should be about .6 of the disc area of 360 or approximately 220. The cosine length of each blade or that length indicated by,

the dimensional line C should be about 220 divided by the number of blades. The number of blades may be governed by compromise but experiment indicates the fewer number of blades employed increases the efficiency of the fan because each blade sets up a turbulence in its wake Awhich the following blade moves into. Experiment indicates a better eiiiclency when the blades move into a'solid medium which is the opposite of turbulence. However, a one-bladed 'fan is impossible to balance dynamically and a two-bladed fan is too deep axially if the pitch is high; In the instance of a two-bladed or any fan comprising blades of an equal number, they are inclined to be noisy because opposite blades go into beat with each other. The best practical design therefore is secured from a three-bladed fan. The cosine length indicated by the dimenuw of snis the product of velocita, u

follows that as the stream contracts the velocity v increases in the same ratio. Therefore, the velocity of the fluid through the propeller or fan is Vaccelerated from zero in the leading edges to a maximum at the trailing edges. Knowing the velocity at various pointson the blade and the Y geometric' pitch at these same points, the consionalline C in Figure 15 in degrees is therefore y 220 divided by 3, or about 7 3".

The secant length of the blade is determined by projecting a tangent from the cosine through the geometrical pitch. The method of arriving at the mean geometrical pitch has been given above. In order to determine the correct accelerated geometrical pitch, reference may be had to Figures 13 and 22 in which the air streams are shown by arrows. In Figure 22 the air streams move toward the center of the bladev as they flow through the blade, which is to say, the stream conn-acts. In Figure 12 the air streams shown by the arrows move away from the center of the blade or diverge outwardly in a direction away from the trailing edges of the blades and the stream of air expands.

VReferringagaintol'igure'22.1:ince'thequan- 1g to reduce the friction of ilow, may be produced as follows.

Figures 17, 18, 19 and 20 correspond respectively to Figures 25, 26, 27 Aand 28, except that in the first instance the fan is in the form of a 4 vena expanda and in the latter instance the fan is in the form of a vena contracta so that the blade sections'are curved reversely to each other. However the same description may have reference to either set of figures. With reference to- Figures 16 and 23, each ofthe cosines has been divided into ve equal distances indicated by the reference characters R0, Ri R2, R3,

R4 and R5. When the leading edge of the fan Y moves from R5 to R0, the fluid in a body is mov ing from 0V to 5V. The individual particle of the air stream is moved from IV to V5 along the secant. The acceleration of the particle from 6V to V5 is in proportion to the contraction of the stream while flowing from IIV to 5V. The

ratio of contraction at each point from IV to IV is shown by the line VC in 1'7gure22 from which figure the relative distances corresponding to relative velocities are shown' byv IV to 6V (Fig. 17) respectively. With reference to Figure 25,

points established by the intersection of the linev 12. The same measurements are laid out withrespect to the different radii on the blades and the sections at such intersections of the radii are determined. vFigure 26 shows the pitch at .8 of the radius or as taken on the line 25-25701 `Figure 20. Figure 27,"represents the pitch at .6

of the radius or as indicated on the yline 21-21 of Figure 21. Figure 28 indicates the pitch at .4 of the radius or as taken on the line 26-28 of Figure 2l. The above is also true with respect to Figures V17, 18, 19 and 20, as to pitches at the various radii'indicat'ed thereon.

In each of the propellers illustrated in Figures 4, 12, 13, 22 and 30 of the drawings, the blades of the. propellers extend from substantially conicalshaped hollow hubs. The open ends of these hubs overlie at least a portion of one end of the motor and are spaced therefrom to provide an air passage therebetween. The hubs are provided with openings preferably one for each blade situated adjacent the blade on the conical surface of the hub for inducing a suction draft around the motor in a direction counter to the no nnai air flow produced by the blades in motion. Referring now more particularly to Figure 24, the section is taken on line 26-24 of Figure 21 and is av development therethrough. The rotational motion is indicated by the arrow X in Figure 2 4.- The air stream vindicated by the letterAontheeonical surfaces createsalowpressure area at L which lowpressure has the effect of producing an air iiow indicated by the letter F through the opening from within the hollow `air stream produced by the fan lblades.

'of the drawings, the air conditioning and heating apparatus therein shown comprises the cabinet,

shield and casing of the previously described embodiments, the air ow therethrough being identically the same. The air mover 45a is of the suction type similar to the air mover 45 of the previous embodiments, although in the instance of the present modification the air propeller 'Il Icomprises a plurality of blades modied slightly in contour for producing a desired suction draft within the apparatus. 'Ihe peripheral edge of each of the blades when the fan, is in motion produces a substantially straight line parallel to the axis of the fan and the shroud structure 18 enclosing a portion of the tipsV of the fan is likewise substantially straight and parallel with the axis of the fan.

'I'he air propeller 1l is mounted on a stud shaft extending from the motor' 19, the motor in turn being housed by an annular shroud 8D spaced therefrom providing air passages therebetween.

The annular shroud 'I8 is mounted in an opening in the cabinet for extension through the shield in any suitable manner and the inner annular shroud 8D is held in a concentric relation with the outer shroud by means of a plurality of struts 8|, one end of each of the struts being secured to the shroud 80 and the other end being secured to the shroud 18.

. Referring now more particularly to Figures 29 v and ,30, the blades of the propeller 'I1 extend radially outwardly from and are secured to a substantially conical-shaped housing 82, the open end of the housing being of sufficient diameter to overlie at least one end of the motor 19. A plurality'of openings 83 are provided in the conical surface of the hub 82, the openings communicating with the air passage formed by the spacing of the motor from the hub. 'Ihe openings 83 create a suction draft within the passages formed between the shroud 80 and the motor 19, and the end of the motor and the hub to draw air over the motor and exhaust vthe same in the normal The action of the apertures in inducing this airow is fully described with reference to Figure 24.

While several embodiments of this invention are herein shown and described, it is to be understood that various modications thereof may be apparent to those skilled in the art without departing from the spirit and scope of this invention and, therefore, the same is only to be limited by the scope of the prior art and the appended claims.

.I claim:

l. Air circulating apparatus for circulating air outwardly through an opening in a wall comprising in combination with said wall, a motor and a propeller driven by said motor, a conically formed hollow hub for the blades of said propeller secured to one end of the shaft of said motor, said hub overlapping the adjacent edge of said motor .in a spaced relation to permit air circulation 'l therebetween, a housing surrounding said motor, an annular seat in said housing for detachably receiving said motor, said housing having. its inner edge in telescoping relation with said conical hub, the outer edgekof said housing being ared outwardly away from said motor, means for supporting said housing adjacent said wall opening-means to induce a suction draft to circulate air drawn inwardly from an area in front of said opening protected by said outwardly ilared housing end from the outwardly moving air stream -created by the driven propeller blades, and means for passing .said inwardly drawn air over said motor and discharging it into said out'- wardly moving air stream created by said rotating propeller blade at said point of overlap between said hub and said motor.

2. Air circulating apparatus for crculating air outwardly through an opening in a wall compris- .ing a propeller including a plurality of blades and a hollow conical-shaped hub therefor positioned to circulate air outwardly through said opening, an annular housing in concentric relation with said hub having its outer edge flared outwardly to extend out of said opening so as to spread into an annular stream the air circulated through` to circulate the same to cool said motor and to exhaust it through said annular air passage tween said hub and'said housing.

3. Air circulating apparatus for circulating air outwardly through an opening in a wall comprising a propeller including a plurality of blades and a hollow conical-shaped hub therefor positioned to circulate air4 outwardly through said opening, a motor for driving said propeller, saidl motor being seated so asto extend into said hub, means for supporting said motor and propeller, said means surrounding said motor and extending outwardly fromv said openingto spread the air circulated 'by said blades into an annular stream in a direction away from said motor, and

means for inducing a suction draft to ldraw air inwardly from an area substantially centrally in front of said openingvand circulate the same over said motor but within said means surrounding said motor and to exhaust the same, substantially at said hub, into said air stream created. by said propeller blades.

4. Air circulating apparatus for circulating air outwardly through an opening, in a. wall com- A prising a propeller including a pllirality of blades and a hub therefor positioned to circulate tem-- perature conditioned air outwardly through said opening, a motor for driving said propeller, means for supporting said motor and propeller, said means surrounding said motor and extending outwardly from said opening so as to spread said temperature conditioned air into an expanding annular stream moving in a radial direction away from the area centrally in front of lsaid opening, and means for inducing a suction draft to circulate. air of a cooling temperature inwardly from an area substantially centrally in front of said opening and to pass the same about said motor and to discharge it into said temperature conditioned air at the end of said motor adjacent said hub.

from the outwardly ing a propeller including a plurality of blades and a hub therefor positioned to circulate temperature cor: litioned air outwardly .through said opening, a motor for driving said propeller, means for supporting said motor and propeller, said means surrounding said motor and extending outwardly from said opening so' as to spread said temperature conditioned air into an expanding annular stream moving in aradial direction away from'the area centrally in iront of said opening, a. grille adapted to be secured to said wall to support said means, motor and propeller as a unit centrally within said opening, andasume A airmrtwardlythroughan'openinginawallcomprlsingapmpellerinchxdingapluralityofblades andahub theretorepodtionedtocirculatetemperature conditioned airoutwardly throughsaid opening,amotoriordrivingsaidpropeller,

means for supporting said motor and propeller,

said means having itsouter end iiared zaudits innerendpositionedwithrespecttoth'etraiiingVv edge oi' said bladessoastocause said temperature conditioned air circulated by said blades to spread radially away from the center of said opening into an expanding substantially annular stream, and means for inducing a suction draft to circulate air of a cooling temperature inwardly from an area substantiallycentrally in iront of said opening and to pass the same about said motor and to discharge itat the rear oi'aidv motor.

' JAMES M. FUNK.

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