US2942439A

US2942439A - Self-contained air conditioning unit employing mixed flow fan

Info

Publication number: US2942439A
Application number: US693635A
Authority: US
Inventors: Edward M Wuesthoff; Gerald P Marcy
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1957-10-31
Filing date: 1957-10-31
Publication date: 1960-06-28
Anticipated expiration: 1977-06-28

Description

June 28, 1960 E. M. WUESTHOFF ETAL 2,942,439

SELF-CONTAINED AIR CONDITIONING UNIT EMPLOYING MIXED FLOW FAN Filed Oct. 31, 1957 2 Sheets-Sheet 1 June 28, 1960 E. M. WUESTHOFF ET L SELF-CONTAINED AIR CONDITIONING UNIT EMPLOYING MIXED FLOW FAN 2 Sheets-Sheet 2 Filed 001;. 31, 1957 INVENTORS EDWARD M.WUESTHOF'F, GERALD P. MARCY. 9%.-

ATTORNE 4 H -w w \LMV SELF-CONTAINED AIR CONDITIONING UNIT EMPLOYING MIXED FLOW FAN Edward M. Wuesthotf, Agawam, and Gerald P. Marcy,

Longmeadow, Mass., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Filed Oct. 31, 1957, Ser. No. 693,635

3 Claims. (Cl. 62-429) This invention relates to air conditioning apparatus and particularly to self-contained air conditioning units of the type adapted to be mounted in a window or other opening in the wall of a building.

Self-contained air conditioning units are generally employed to condition the air within a single residential room or confined ofiice space, and it is therefore desirable that such units be made as small and unobtrusive as possible. Moreover, when mounted in a window, or other wall opening, the unit should not appreciably overhang or project beyond the wall either interiorly or exteriorly of the building. These considerations limit the front to back dimension of the air conditioning unit to approximately 15" and present problems in the location and arrangement of components within the unit.

In compact air conditioning units, most of the space therein is occupied by the several components of the refrigerating system and but little space is available for eflicient air flow passages. Prior attempts to design selfcontained units of minimum dimensions have often resulted in units that are both noisy and inefiicient; these deficiencies being the direct result of restricted or cramped .air flow arrangements necessitated by the small size of the units.

This invention provides an improved arrangement for circulating air through the air conditioning unit and the heat exchangers located therein, which arrangement enables the required quantities of air to be circulated both quietly and efiiciently through a unit of small size.

In accordance with the invention, a mixed flow fan is employed in a novel manner and to substantial advantage in moving air through a confined and tortuous flow path. A mixed flow fan can be briefly characterized as one in which the blades are constructed in a manner to draw air axially into the fan and to discharge air radially from the fan, and wherein the air is turned through a 90 angle within the confines of the fan. This fan is located directly behind a heat exchanger within a space of limited depth between the heat exchanger and a barrier or partition arranged parallel to the heat exchanger. The barrier carries a motor which drives the fan, and the motor, for space conserving purposes, is partially encompassed by the fan. The fan is constructed to draw air through the heat exchanger and is preferably assisted in performing this function by a shroud surrounding the heat exchanger and the inlet portions of the fan blades. After passing through the heat exchanger and entering the fan, the air is turned at right angles to the axis of the fan and directed parallel to the plane of the heat exchanger. A scroll casing partially encompassing the fan directs the air discharged by the fan into an air passage that conveysthe air around the heat exchanger and out of the unit.

A feature of this invention is the small depth of space occupied by the heat exchanger, the fan and the drive 'motor for the fan. The compact arrangement enables an airconditioning unit to be constructed with a minimum atent V 2,942,439 Patented June 28, 1 960 front to back dimension without sacrificing efliciency in the air circulating system. The use of a mixed-flow fan eliminates the necessity for providing lengthy air flow passages axially ahead of or behind the fan but, since a comparatively large diameter fan is employed, uniform air flow over the entire flow area of the heat exchangeris assured. 7

Other features, objects and advantages of the invention will appear from the following detailed description of a prefer-red embodiment thereof, which descriptionincorporates the accompanying'drawings wherein:

Fig. 1 is a perspective view illustrating the front, or room side, of a self-contained air conditioning unit embodying this invention;

Fig. 2 is a horizontal sectional view through an upper portion of the unit, which view is taken as indicated by the line II-Il in Fig. 1;

Fig. 3' is a front view of the unit with portions thereof broken away to show the interior;

Fig. 4 is a vertical sectional view through the unit taken as indicated by the line IV-IV in Fig. 3; r

Fig. 5 is another sectional view of the unit taken as indicated by the line VV in Fig. 2;

Fig. 6 is a perspective view of the mixed-flow fanernployed in this invention; and,

Fig. 7 is an end view of one of the blades of the fan shown Fig. 6.

Referring to the drawings in detaihthe components of the self conta-ined air conditioning unit there illustrated are housed within a casing 11 having a front surface, or

room air face ll and a rear surface,.o r outside air face,

13. The casinglll is of simple box-like'configuration to enable the unit to be easily mounted within aw-indow or other opening in a'building wall in such a manner that the front surface 12 thereof faces interiorly of the room, or other enclosure to be air conditioned, and the rear surface 13 of the unit is exposed to outside air.

Disposed within the casing 11 is a horizontal tray or pan 14 on which the components of the air conditioning the

heat exchangers

18 and 19 by a motor-compressor 20 mounted on the pan 14 in the outside air chamber 17. The

heat exchangers

18 and 19 and the motor compressor 20 are connected in series flow relationship by means of suitable conduits (not shown) to form a conventional compressor-condenser-expander refrigerating system, whereby one of the heat exchangers functions to absorb heat, and the other heat exchanger functions to dissipate this heat. Generally, the room air heat exchanger 18 functions as an evaporator, or heat absorbing element, for the system to cool and dehumidify room air that is circulated therethrough. The outside air heat exchanger 19 is, therefore, generally employed as the con,- densing, or heat dissipating, element of the system. It is not uncommon, however, for air conditioning units of the type here described to include provisions for reversing the functions of the

heat exchangers

18 and 19 to add heat to the air in the room being conditioned. The general principles of operation of the self-contained air conditioning unit are well understood by those skilled in the art and this invention proposes no alteration of these principles.

This invention is particularly concerned with the psysical arrangement of the components of the air conditionaaaaasa a ing unit within the casing 11 and envisions an arrangement that insures efficient air flow through the interior of the unit. Referring particularly to Figs. 2, 3 and 4, it will be noted that the room air heat exchanger 18 has a flat, rectangular shape and is mounted vertically adjacent the front or room air surface 12 of the casing 11. This heat exchanger 18 is of finned tube construction, with the fins so arranged as to permit air to pass horizontally through the heat exchanger. Room air is drawn through the heat exchanger 18 by means of a fan 21 disposed directly behind the heat exchanger and mounted for rotation about a horizontal axis on a shaft extending from one end of a motor 22.

The fan 21 is of multiblade construction and has mixed flow characteristics that permit the fan to draw air axially into itself and discharge air at right angles to its axis of rotation. The fan 21 is thus adapted to be mounted between the closely spaced surfaces of the heat exchanger 18 and the barrier and, because the air propelled by the fan is turned within the confines of the fan, but small clearances need be provided at either the front or the rear edges of the fan blades.

The principal characteristics of the fan 21 can be ascertained by reference to Figs. 6 and 7. It will be noted that the fan 21 is made up of a plurality of radially extending blades 23 mounted on a frusto-conical hub plate 24 by means of tab portions 25 bent from the blades and welded or otherwise secured to the hub plate. Each blade 23 is formed from sheet metal, or other rigid sheet material, and has a uniform radius of curvature across its face. Each blade is mounted on the hub plate in such a manner that a plane tangent to the surface of the blade at its trailing edge 26 is substantially parallel to the axis of rotation of the fan. The leading edge 27 of each blade is curved forward in the direction of rotation of the fan and a plane tangent to the surface of the blade at the leading edge is oblique with respect to the axis of rotation of the fan and approaches being at right angles to that axis. In other words, each blade is formed from a sheet approximating one-quarter of a cylindrical tube.

That portion of each blade 23 of the fan 21 that is contiguous to the leading edge 27 of the blade can be termed the inlet or entry portion of the blade and is identified in the drawings generally by the reference numeral 28. Because the inlet portion 28 of each blade is disposed at a substantial angle to the axis of rotation of the fan, this portion of the blade acts to draw air axially into the fan. It is common practice in fan design to shape the leading edge of the fan blade so that for a particular rotational speed the air enters the fan without shock. This condition is achieved when the tangent to the blade at the leading edge is substantially parallel to the direction of relative movement of air entering the fan. In the particular fan employed in this invention, a constant radius of curvature is maintained across the blades 23 throughout their radial extent and the desired angles at various sections of the inlet portion of each blade are achieved by simply cutting away, or omitting, beveled portions of the leading edge of each blade. (See Fig. 6.)

The portion of each blade 23 that is contiguous to the trailing edge 26 of the blade can be termed the delivery" portion 29 of the blade and functions to propel air radially outwardly from the fan. The delivery portion 29 is at substantially right angles to the direction of movement of the fan blade so that this portion 29 of blade functions as a centrifugal impeller. The delivery portions 29 of the blades 23 are disposed around the projecting portion of motor 22 so that the trailing edges 26 of the blades are close to the barrier 15.

It can thus be seen that the fan blades are constructed in a manner to cause air to enter the fan 21 axially and be expelled therefrom radially; the air flow path being mixed, or turned, within the fan. The fan blades 23 are assisted in efiecting a 90 chang e'of 'dir'ectio'nof the air moving through the fan by the frusto-conical hub plate 24 and the barrier 15 that is disposed close to the trailing edges 26 of the blades. The frusto-conical hub plate imparts a radial component of motion to air entering the central region of the fan, and the barrier 15 confines the bulk of the air to the effective area of the delivery portions 29 of the fan blades so that the blades can act on and propel the air effectively.

The mixedflow fan 21 is particularly effective in drawing air through the entire flow area of the heat exchanger 18, although the fan 21, for reasons of space conservation, is located iclo'sely behind the heat exchanger and but a short th'ro'at area is provided for the fan. This uniform air flow through the heat exchanger is attributable to the comparatively large diameter fan employed in this arrangement. It will be noted that the fan 21 has a diameter approaching the height of the heat exchanger 18 and that both the heat exchanger and the fan have verticaldiniensions that are well over one-half the height of the air conditioner casing 11. For most efficient results, the face of the heat exchanger 18 is approximately square so that this flow area coincides as nearly as possible with the axial flow area of the fan.

The fan 21 is assisted in performing the function of drawing air through the heat exchanger by a shroud 33 that is joined to the periphery of the heat exchanger 18 and extends rearwardly to the fan 21. This shroud 33 has a circular outlet 34 of a diameter slightly greater than the diameter of the fan 21 and which surrounds the inlet portions 28 of the fan blades 23. In other words, the shroud 33 extends rearwardly a distance sufficient to encompass the inlet portions 28 of the fan blades 23 to direct air axially into the fan 21. The shroud 33 does not, however, extend over the discharge portions 29 of the fan blades 23 and a flow space is therefore provided for air moving radially outward from the discharge portions 29 of the fan blades.

The air discharged radially from the fan 21 is directed into a generally vertical flow path by means of a scroll casing 36 partially encompassing the fan 21 and having an upwardly directed outlet opening (see Fig. 5). From the scroll casing 36 the room air flows into a discharge passage 37 extending across the top of the heat exchanger 18 and terminating at an outlet grille 38 through which the air is discharged from the air conditioning unit. The air discharge passage 37 extends across the entire width of the casing 11 in order that sufficient air flow area can be provided in a passage that has a small vertical dimension. The use of a wide but low air discharge passage 37 permits a substantial portion of the vertical height of the casing 11 to be employed for the purpose of housing the room air heat exchanger 18 and the fan 21.

It has been ascertained that a smooth, efficient flow of air into and through the air discharge passage 37 can be best achieved by providing a turning vane 39 in the inlet region of the discharge passage 37 above the outlet of the scroll casing 36. The turning vane 39 assists the air in executing a turn in the passage 37 from a vertical to a horizontal flow path. Air flow through the discharge passage 37 can be further improved by providing an air foil like rolled top 41 on the part of the shroud 33 that covers the top of the heat exchanger 18. This rolled top 41, like the turning vane 39, assists the 'air flowing through the discharge passage 37 in making the transition from vertical to horizontal fiow.

Some of the advantages and features of the above described air flow pattern for the room air heat ex changer 18 can be summarized as follows: Foremost of the advantages in this arrangement is the short depth of space occupied by the components. The use of a mixedflow fan 21 permits the fan to be located closely adjacent the surface of the heat exchanger 18 and permits the barrier 15 and the motor 22 to also belocated but a short distance to the rear of the heat exchanger 18. Thus, the front to back space required for the room air chamber 16 of the air conditioning unit is held to a minimum. The heat exchanger 18 and the fan 21 are, in accordance with this invention, permitted to occupy a substantial vertical extent of the air conditioner casing 11. A relatively largediameter fan 21 can, therefore, be employed which is, in itself, eflicient and which insures uniform ai-r flow through the heat exchanger 18. Adequate discharge air flow is provided by extending the discharge passage 37 across the width of the casing 11. While a substantially square heat exchanger 18 is preferred, the space to the side of the heat exchanger is not wasted as this space is employed to house the controls which must be provided for the air conditioning unit and which are indicated in the drawings at 42 (see Figs. 2 and 5). The space to the side of the fan 21 and the scroll casing 36 is employed to house the motor compressor 20 which is generally a bulky item requiring considerable space within the casing 11.

As shown in the drawings, the above-described features of the air flow pattern for the room air heat exchanger 18 can be applied to the outside air'heat exchanger 19 to further conserve space within the air conditioner casing 11. For example, a mixed-flow fan 45 similar to the fan 21 previously described is employed to draw air through the outside air heat exchanger 19 and to discharge this air around the heat exchanger and out of the casing 11. The fan 45 is preferably driven by the same motor 22 that drives the room air fan 21 and the discharge portion of the fan 45 encompasses that portion of the motor 22 that projects from the barrier 15 into the outside air chamber 17. The outside air heat exchanger 19 has a shroud 46 that extends over the inlet portions of the blades of the outside air fan 45 for the purpose of directing air axially into the fan 45. A scroll casing 47 partially encompasses the outside air fan 45,

confines the air flowing radially from the fan 45, and

directs this air over the motor compressor 20 and around the top and side of the heat exchanger 19.

From the foregoing it should be apparent that this invention provides for efiicient circulation of air through the interior of a self-contained air conditioning unit and 'through the heat exchanger disposed within the unit. It

should also be apparent that the arrangement of components provides an air flow pattern requiring less space than has been devoted to similar air flow patterns in prior air conditioning units. The invention thus enables air conditioning units to be constructed that have smaller overall dimensions than prior units employing the same size components. The invention is particularly effective in reducing the required front to back depth of the air conditioning unit and, when similar air flow patterns are utilized for both the room air heat exchanger and the outside air heat exchanger, as illustrated in the disclosed embodiment of the invention, a minimum size unit is obtained. The above-mentioned advantages with regard to size reduction are achieved without reducing the efficiency or increasing the noise production of the air flow system because of the particular arrangement and selection of the components for the system.

While the invention has been shown in but one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various changes and modifications without departing from the spirit thereof.

What is claimed is:

1. In an air conditioning unit of the type adapted to be supported in a window or other opening in a building and having front and rear surfaces facing, respectively, interiorly and exteriorly of the building, a heat exchanger disposed vertically adjacent one of the said surfaces of the unit, a multi-blade, mixed-flow fan disposed in the unit directly behind said heat exchanger for drawing air through said heat exchanger, said fan being said heat exchanger, the blades of said fan being radially disposed and having inlet portions obliquely disposed with respect to the axis of the fan for directing air axially into said fan and delivery portions disposed substantially parallel to the axis of the fan for deliveringair from said fan at right angles to the axis thereof, a shroud extending between said heat exchanger and said fan for causing air entering said fan to be drawn through said heat exchanger, said shroud having a circular exit portion of greater diameter than said fan and disposed to encompass the blade inlet portions of the fan, a barrier disposed behind said fan in close proximity to the edges of the fan blades, said barrier being disposed substantially normal to the axis of the fan for assisting the fan in directing the air delivered by said fan, a motor for driving said fan, a scroll casing partially encompassing said fan and defining an upwardly directed outlet, and means defining an air delivery passage communicating with the outlet of said scroll casing and extending to the said surface of the unit for discharging air from said unit.,

2. In an air conditioning unit of the type adapted to be supported in a window or other opening in a building and having front and rear surfaces facing, respectively, interiorly and exteriorly of the building, a rectangular heat exchanger disposed vertically adjacent one of the said surfaces of the .unit, a multi-blade, mixed-flow fan disposed in the unit directly behind said heat exchanger, said fan being rotatable about a substantially horizontal axis normal to said heat exchanger, the blades of said fan being radially disposed and having inlet portions obliquely disposed with respect to the axis of the fan for directing air axially into said fan and delivery portions disposed substantially parallel to the axis of the fan for delivering air from said fan at right angles to the axis thereof, a shroud extending between said heat exchanger and said fan for causing air entering said fan to be drawn through said heat exchanger, said shroud having a circular exit portion of greater diameter than said fan and disposed to encompass the blade inlet portions of the fan, a barrier disposed behind said fan in close proximity to the edges of the fan blades, said barrier being disposed substantially normal to the axis of the fan for assisting the fan in directing the air delivered by said fan, a motor carried by said partition for driving said fan, said motor having at least a portion thereof projecting from said barrier and encompassed by the delivery portions of said fan blades, a scroll casing partially encompassing said fan and defining an upwardly directed outlet, and means defining an air delivery passage communicating with the outlet of said scroll casing and extending to the said surface of the unit for discharging air from said unit.

3. In an air conditioning unit of the type adapted to be supported in a window or other opening in a building and having front and rear surfaces facing, respectively, interiorly and exteriorly of the building, a pair of heat exchangers, said heat exchangers being disposed vertically and in substantially parallel planes at, respectively, the front and back of the unit, a barrier disposed between and substantially parallel to said heat exchangers, a motor carried by said barrier and having end portions projecting from opposite sides of the barrier toward said heat exchangers, a first mixed-flow fan mounted on one end of said motor and adapted to draw air through one of said heat exchangers, a second mixed-flow fan mounted on the other end of said motor and adapted to draw air through the other of said heat exchangers, said fans being rotatable about a common axis arranged substantially normal to said heat exchangers, each of said fans having blade inlet portions obliquely disposed with respect to the axis of the fan for directing air axially into the fan and blade delivery portions disposed substantially parallel to the axis of the fan for delivering air fromthe fan at right angles to the axis of the fan, the blade delivery portions of each of said fans being disposed to encompass .7 3 their respective projecting end portions of said motor References Cited in the file ofthis patent and tn extend into close proximity to said barrier, vrhere- UNITED STATES PATENTS by said barner asslsts 831d fans 1n dlrectlng the arr der A V v livered by the fans, and means defining air discharge 2,199,031 Sperry. 4 passages for receiving air delivered by each of said fans 5 g g -1 z s and for conve in that air out of the unit. y g 2,806,361 Kline et a1. Sept. 17, 1957 2,811,023 Lathrop Oct. 29, 1957 2,823,852 Busch Feb. 18, 1958