US3122307A

US3122307A - Fan equipment

Info

Publication number: US3122307A
Application number: US130049A
Authority: US
Inventors: Robert A Wasson; Sewell H Downs
Original assignee: CLARAGE FAN CO
Current assignee: CLARAGE FAN CO
Priority date: 1961-08-08
Filing date: 1961-08-08
Publication date: 1964-02-25
Anticipated expiration: 1981-02-25

Description

Feb. 25, 1964 R WASSON .ETAL 3,122,307

FAN EQUIPMENT 2 Sheets-Sheet 2 Filed Aug. 8. 1961 INVENTORS PUB/5P7 A. W4 550/V SEWELL H. DOW/V5 A Tram/2w United States Patent 3,122,307 FAN EQUIPMENT Robert A. Wasson and Sewell H. Downs, Kalamazoo, Mich, assignors to Clarage Fan Company, Kflamazoo, Mich a corporation of Michigan Filed Aug. 8, 1961, Ser. No. 139,049 7 Claims. (Cl. 230-117) This invention relates in general to a combination fan construction including housing structure having a pair of coaxial, annular passageways and an impeller assembly including a centrifugal impeller and an axial flow impeller connected to each other and rotatably supported for effecting the axial flow of gas through the two passageways simultaneously in opposite axial directions. The use of dual impellers mounted for simultaneous rotation is very old in the art. However, it is relatively new in the art to use a combination centrifugal and axial flow impeller for the purpose of effecting simultaneous, counteraxial flow of a gas, such as air, through a pair of radially aligned, annular passageways, particular for the purpose of exchanging the air within a space with which said passageways communicate. Many attempts, which have been largely unsuccessful, have been made to develop a dual fan construction for use in the heating and ventilating field. However, there has been little interest in, hence acceptance of, dual fan constructions for this purpose.

It is believed that the lack of widespread acceptance of dual fans has been due largely to the fact that previous dual fan constructions, particularly in the field of ventilation, have used a pair of radially aligned and interconnected axial flow fans. It is a well known fact that axial flow fans, which are economically competitive with a conventional centrifugal fan, are incapable of developing total pressures which are often required in ventilating installations. Moreover, in order to have a comparable capacity, axial flow fans (particularly propeller types) must be operated at tip speeds which create unacceptable noise levels, especially for installations adjoining space occupied by humans. Because of their relatively low static pressures, conventional dual propeller units used for this purpose must be placed close to the air space which they are serving, thereby aggravating the noise problems.

The two coaxial passageways, which are required in this type of structure, generally have cross-sectional areas which differ very substantially. Heretofore, it has been very difficult to develop a dual propeller fan construction which provides large, balanced flows of supply and exhaust air through said passageways without encountering costly blade configurations, high impeller velocities (hence noise) and/ or high power losses due to turbulence and other obstructions to the air flow. Moreover, even when these problems have been minimized by careful and costly designing, the dual propeller fan construction has been very restricted in its application because of its inability to develop, particularly in the exhaust passageways, the necessary static pressure to utilize ducts in association therewith for more uniform circulation.

In the process of studying these various problems, the applicants developed a combination impeller construction whereby substantially all of the above discussed problems are materially reduced, if not eliminated, and, more importantly, without creating new problems.

Accordingly, a primary object of this invention has been the provision of a combination fan construction wherein a centrifugal impeller is connected to and driven simultaneously with an axial flow fan so that a single unit having coaxial exhaust and supply passageways can be effectively and efficiently used without high noisy tip speeds, which can be conveniently and acceptably installed adjacent the air scape which it serves, which can be manufactured at a cost competitive with dual propeller fan constructions for the same or similar purpose, and which is capable of producing more efiicient performance and developing greater capacities than existing competitive constructions.

A further object of this invention has been the provision of a combination fan construction wherein the supply passageway is on the outside and a propeller fan is located therein to use the axial flow fan where it is most efficient (i.e. of largest diameter) and its relatively smaller capability for developing static pressure will not adversely affect the operation of the unit; and wherein the centrifugal impeller is used in association and communication with the inner and small, exhaust passageway where the higher static pressures are desired.

A further object of this invention has been the provision of a combination fan construction wherein the obstruction of the discharge of exhaust gases from the centrifugal impeller is reduced to a point far below that which is normally encounteded by the discharge of exhause gas from an axial flow impeller used under the same circumstances, due primarily to the normal char acteristic of the centrifugal impeller to discharge radially; and wherein the capacity of the centrifugal impeller is so much greater than the axial flow impeller normally used in the same location that the combination fan construction can be satisfactorily used for ventilating not only the air space adjacent the unit but at substantial distances therefrom and connected thereto by substantial amounts of duct work.

A further object of this invention has been the provision of a combination fan construction, as aforesaid, which can utilize a conventional centrifugal impeller and a conventional axial flow impeller with little or no modification or variation required to effect their combination, and wherein said combined centrifugal and axial flow impellers can be arranged to provide a high capacity fan construction with a minimum of obstructions to the free flow of gas therethrough in both directions while, at the same time, permitting a housing construction which is much smaller than the housing structure required for dual propeller fan constructions capable of performance even approaching the performance of the applicants construction.

Other objects and purposes of the invention will become apparent to persons familiar with equipment of this kind after reading the following descriptive material and examining the accompanying drawings, in which:

FIGURE 1 is a side elevational view of a combination fan construction embodying the invention.

FIGURE 2 is a sectional view taken along the line II-II in FIGURE 1.

FIGURE 3 is a broken sectional view substantially as taken along the line lII-III in FIGURE 2.

For convenience in description, the terms upper, lower and words of similar import will have reference to the fan construction as shown in FIGURES 1 and 2 which disclose one normal position of its operation. The terms inner, outer and derivatives thereof. will have reference to the geometric center of said fan construction and parts thereof.

General Description The objects and purposes of the invention, including those set tfOIllll above, have been met by providing a combination fan construction comprised of a housing having wall structure defining inner and outer, substantially coaxial annular passageways and a dual impeller rotatably supported within the housing for effecting simultaneous, counteraxial flow of gas, -such as air, through said passageiways. The dual impeller is comprised of a centrifugal impeller or wheel which has an inlet communicating with the inner, annular passageway and another impeller, such as an axial flow fan, located in or adjacent to the outer annular passageway whereby rotation of said dual impeller eifects exhausting of air through one passageway and supplying of fresh air through the other passageway. Sui-table means are provided for effecting rotation of said dual impeller and bathing means is provided for insuring separation between the ambient source of air supply and the exhaust air. The combination fan of the invention is especially suited for mounting upon a horizontal wall, such as a roof, for exchanging the gas, such as air, in the space below said wall or roof including space connected to said fan unit by ducts and disposed at substantial distances from the space directly below the unit. However, said combination fan construction can also be mounted with equal efiectiveness upon a substantially vertical wall for the same or similar purposes.

Derailed Construction The combination fan construction 14} (FIGURES 1 and 2), which illustrates a preferred embodiment of the invention designed for roof mounting is comprised of an impeller housing 11 in which a dual impeller 12 is rotatably supported and rotated by a drive mechanism including at least a motor 13, which may drive the impeller through coupling means, such as the belt arrangement shown in FIGURE 2. The motor 13 may be supported upon the housing 11 within a motor cover 14. The housing 11 may be supported upon a base 16 which is in turn mounted, for example upon the roof 17 above the space being serviced by the fan construction 10.

The base 16 is preferably, but not necessarily, a \substantially flat and rectangular structure having a horizontal top wall .18 and a substantially vertical flange 19 extending partially or completely around and downwardly from the perimeter of the top wall 18. Additional, intermediate support elements, suoh as that indicated at 22 in FIGURE 2, may be provided between the roof 17 and top wall 18 for supporting purposes, if necessary. The top wall 18 has a central opening 23 and may be provided with an integral circular fiange 24 around said opening for reasons appearing hereinafter.

The base 16, the impeller housing :11, the dual impeller 12 and many of the parts associated therewith are preferably, but not necessarily, fabricated from relatively still" and durable material such as sheet metal, bar stock, metal castings and the like.

The impeller housing 11 (FIGURE 2) includes an outer cylindrical casing 26, the lowerend of which is snugly sleeved around and secured as by welding to the flange 24. Where, as in this embodiment, the fan construction 10 is disclosed as a roof mounted ventilator, the cylindrical casing 26 is axially upright and open at its upper and lower ends. An inner cylindrical wall me ber 27 is concentrically disposed within and supported upon the casing 26 by the plates or brackets 28. The outer casing 26 and cylindrical wall member 27 define between them an outer, annular passageway 29 which communicates between the upper end of the casing 26 and the central opening 23 in the base 16.

The roof 17 (FIGURE 2) is preferably provided with a circular opening 3-2 which is preferably coaxial with and slightly larger than the central opening 23 in the top wall 18. A cylindrical sleeve or duct 33 may be snugly disposed within the circular roof opening 32 so that it extends toward and adjacent the top wall 18. Means, such as a cylindrical duct 34, may be sleeved upon the lower end of the wall member 27 in a conventional manner for communicating between the lower end of the wall member 27 and a selected air space within the zone below the roof 17. Thus, the two cylindrical ducts 33 and 34 define, in effect, a continuation of the outer, annular passageway 29.

The bearing assembly 36 includes a pair of axially spaced, coaxial bearings 37 and 38, which are supported upon and within the opposite ends of cylindrical tube 39. Said tube 39 is supported coaxially within and upon the cylindrical wall member 27 by support brackets 42 which are secured to and extend between the tube 39 and wml member 27. The upper end of the bearing assembly 36 extends substantially above the upper end oi the wall member 27 for rotatably supporting an impeller shaft 43 coaxially within the wall member 27. The wall member 27 and the lower end of the tube 39 define between them an inner annular passageway 44 which communicates at its lower end with the cylindrical duct 34.

(The dual impeller 12 (FIGURE 2) includes a centrifugal fan wheel 46 which may be of any convenient type. in this particular embodiment, and for illustrative purposes only, said wheel 46 is comprised of a back plate 47 supported upon and secured to a hub 48 which is mounted upon the shaft 43 above the bearing assembly 36 and secured to said shaft by means including a set screw 49. The wheel 46 has a plurality of blades 52 secured at one end of each to said back plate 47 and at the other end of each to a rim 53, which defines a wheel inlet opening 54. Means, such as a pair of set collars 56 and 57, are secured to the shaft 43 adjacent the upper and lower ends, respectively, of the bearing assembly 36 to prevent axial movement of the shaft 43 with respect to said hearing assembly. 7

A conical ring 53 is coaxially secured, as by welding, to the lower side of the rim 53 adjacent to the periphery thereof so that said ring 58 converges downwardly and has an inside diameter about equal to the inside diameter of the rim 53. A cylindrical sleeve or inlet pipe 61 is coaxially secured, as by welding, to the lower edge of the conical ring 58 and extends downwardly therefrom toward and adjacent the upper end oi the wall member 27. In this particular embodiment, the sleeve 61 is somewhat smaller diameter than the cylindrical wall member 27. However, this specific arrangement may be varied depending upon the specific details of construction required by the particular installation. Moreover, it will be apparent that the rim 53 may, under some circumstances, be omitted by extending the lower ends of the blades 52 downwardly so that they are secured to the ring 58 or alternatively, that the conical ring SSmay be omitted under some circumstances by extending the sleeve 61 up to the rim.

The dual impeller 12 also includes an outer impeller 62 (FIGURE 3) which may be or" a substantially conventional type, such as an axial flow fan. In this particular embodiment, the fan 62 is comprised of an annular support member 63 which snugly and concentrically embraces and is secured, as by welding, to the lower end of the sleeve 61 adjacent the upper end of the wall member 27. The outside diameter of the annular support member 63 is approximately equal to the outside diameter of said wall member 27. A plurality of propeller blades 64 are secured, as by the rivets 66, to the peripheral surf face of the support member 63 at uniform intervals there-.

around so that said blades extend radially toward and adjacent the outer casing 26, preferably adjacent the upper ends thereof.

The blades of the outer impeller 62 (FIGURES 2 and 3) are arranged so that rotation of the dual impeller.

12, which efiects the proper radial discharge from the centrifugal Wheel 46, will also cause the outer impeller 62 to move air or gas downwardly through the outer annular passageway 29 while gas is being moved upwardly through the inner annular passageway 44 by the centrifugal wheel 46.

A pair of spaced supports 67 (FIGURE 2) for the motor mounting bracket 68 may in this embodiment, be mounted upon the casing 26 and extend in substantially the same direction therefrom. The motor 13 may be mounted in a conventional manner, as by means of the bolts 69, upon an upright flange 72 of the mounting bracket 68 so that the motor shaft 73 extends vertically upwardly from the motor 13. The motor cover 14 is mounted upon the supports 67 and/ or the casing 26 adjacent thereto. Although a particular motor mounting means is shown and described in this embodiment it should be recognized that, under some circumstances, the motor may be mounted coaxially above or below the shaft 43 and connected directly thereto.

An annular bafiie assembly 74 is spaced upwardly from the upper end of the outer casing 26 and is supported by a plurality of upright support bars 76 which in this embodiment are secured to and connected between the upper end of the outer casing 26 and a portion of said baflle member directly thereabove. The baflle assembly '74 includes a lower baflle ring 75 which is mounted near its inner radial edges upon the support bars 76. The radially outer portion of the battle ring 75 curves from said support bars 76 downwardly and outwardly to terminate in a substantially vertical flange 77 which preferably telescopes slightly and is spaced radially outwardly from the upper end of the outer casing 26. As shown in FIGURE 3, a portion of the batlle assembly 74 is omitted in the region of the motor cover 14 to mount said cover adjacent he outer casing 26. The baflie ring 75 cooperates with the upper end of the casing 26 to define an inlet passage 78 which communicates between a supply of ambient air and the upper end of the outer annular passageway 29 The bafile assembly 74 includes a deflector ring 84 which is concentrically supported upon and secured to the baffle ring 75. The ring 84 has a radially inward por tion 85 curving upwardly and inwardly to meet the periphery of the rim 53. The deflector ring 84 also has a peripheral portion 86 which curves upwardly and outwardly.

The impeller housing 11 includes an inverted, dishshaped cover member 81 which is supported coaxially upon and spaced upwardly from the annular baflle assembly 74 by the support bars 82 which are secured thereto and extend there-between. The diameter of the cover member 81 in thi embodiment is substantially greater than the diameter of the centrifugal wheel 46, which it covers, and is slightly less than the diameter of the baffle member 74. In this arrangement with the shaft 43 being driven from above, the cover member 81 has a central opening 83 through which that portion of the hub 43 containing the set screw 49 extends so that said set screw is accessible. The diameter of the deflector ring 84 is preferably slightly greater than the diameter of the cover member 81 so that air discharged between the deflector ring 84 and the cover member 81 by the centrifugal wheel 46 is deflected upwardly away from the supply of ambient air received into the inlet passage 78.

A driven pulley 87 may be mounted upon the upper end of the shaft 43 adjacent the hub 48 and secured thereto by means including the set screw 88. -A driving pulley 91 is mounted upon the motor shaft 73 by means including the set screw 92. The pulleys 87 and 91 are interconnected by one or more belts 93, whereby rotation of the motor shaft 73 effects rotation of the dual impeller 12.

Operation Although the operation of the combination fan construction It} is probably evident from a reading of the above description thereof, such operation will now be reviewed briefly. With the fan construction It) installed on a roof 17, for example, the cylindrical wall member 27 will normally be connected to some form of duct 34 which will communicate with the space from which gas or air is to be exhausted. Also, the cylindrical wall member 26 may be extended by connection to some form of duct 33 in such a way as to move the air passing downwardly therethrough into zones spaced a substantial distance from the fan construction 10.

By energizing the motor 13, the impeller 12 is caused to rotate in a direction whereby gas or air is caused to move upwardly through the inner annular passageway 44 within the wall member 27 and sleeve 61 toward and through the inlet Opening 54 in the centrifugal wheel 46 and is then discharged in a substantially conventional manner radially outwardly by the blades 52 of the wheel 46, so that it discharge between and radially beyond the cover member 81 and deflector ring 84. As stated above, the deflector ring 84 causes the discharged air to be deflected away from the inlet passage 78 which deflection will usually be augmented by the normal convection currents in the ambient air. The outer impeller 62 will, at the same time, draw air through the inlet passage 78 and move it downwardly through the outer annular passageway 29 into whatever zone or air space may be in communication with the duct 33. A sidewardly opening baffle ring, indicated by broken lines at 94 in FIGURE 2, may be provided for deflecting the air moving through the outer passageway 29 sidewardly away from the air entering the inner annular passage. Although the drawings and much of the discussion disclose operation of the fan construction It) above a roof, a reversed installation is fully contemplated, in which the entire construction is inverted and suspended from the under side of a roof so that the inlet and exhaust functions of the outer and inner impellers would be exchanged. In such an installation appropriate baffles and ducts would be provided.

It is common knowledge that the most eflicient portion of a propeller type or axial flow fan is in the region thereof spaced a substantial distance from the hub, and preferably including that portion thereof near the periphery of the propeller fan. Accordingly, the impeller 12 has been designed, with this fact in mind, so that the propeller fan is located in the outer one of the two annular passageways. =It is also very well known that a centrifugal fan can operate substantially at full capacity and at peak performance where the inlet duct communicating with the inlet of the fan has a diameter about equal to the opening in the inlet side of the wheel. Thus, instead of using a low etiiciency, low pressure type of propeller or axial flow fan in the inner passageway 44. Applicant has arranged to use a relatively high eificiency and high pressure, centrifugal Wheel, which greatly enhances the performance of the fan construction while maintaining an overall size, capacity and cost which are entirely competitive with existing dual fan constructions, utilizing two propeller fans.

It will also be seen that, where the :fan construction 1%? is used in a closed system, any tendency for the propeller fan portion of the impeller 12 to be unable to meet the full requirements for a supply of air will be overcome by a negative pressure condition created in the systorn by the centrifugal fan wheel which will actually induce the flow of air through the outer annular passageway 29 and thereby augment the operation of the propeller fan portion of the impeller.

it has been found that, by controlling the diameters of the annular member 63, the sleeve 61 and the adjacent end portion of the wall member 27, the leakage of air or gas between the annular member 63 and the wall member 27 can be carefully controlled. This condition is aided by the fact that the space between the

members

27 and 63 is downstream of the propeller fan and upstream of the centrifugal fan. Where contamination of the supply air by the exhaust air within the fan construction 10 is undesirable, the diameter of the member 63 is very slightly larger than the diameter of the member 27 in this particular embodiment. As a result, a small amount of air leaks between the

members

27 and 63 from the outer passageway 28 into the inner passageway 44.

Accordingly, the combination fan construction 10 of this invention is not merely another dual fan construction having limited utility and restricted primarily to use for exchanging gas in, or ventilating, the zone immediately adjacent the wall upon which the fan construction is mounted. Applicants fan construction 10 is, on the contrary, capable of a wide variety of uses wherein separate exhaust and supply units of the centrifugal type are presently used in order to provide both the capacity and static pressures which are required, particularly where it is important to hold down the noise which is normally incident to the use of strictly propeller type fan assemblies for this purpose.

In this regard, it will be observed that a typical, slow speed multiblade centrifugal fan wheel will normally be used in the fan construction It) where a ventilating application is involved. Accordingly, the propeller fan which provides the supply air will also be operating at a relative ly low tip speed which will not produce an objectionable noise. Moreover, since the propeller fan is shrouded by the casing 26, such noise will also be reduced somewhat. Since the most efficient outer portion of the propeller fan is being used in the impeller 12, adequate air movement will normally be provided as discussed above.

Although a particular preferred embodiment of the invention has been disclosed above in detail for illustrative purposes, it will be understood that variations or modifications of such disclosure, which come within the scope of the appended claims, are fully contemplated.

What is claimed is:

l. A gas moving apparatus, comprising:

an outer casing of sheet material and circular cross section;

an inner, cylindrical wall member of sheet material and coaxially disposed within and radially spaced from said casing;

means rigidly securing said wall member with respect to said casing;

a shaft, and bearing means mounted upon said wall member and rotatably supporting said shaft coaxially within said wall member, said shaft extending axially beyond one end of said wall member;

a centrifugal impeller concentrically supported upon said shaft externally of and axially spaced from said wall member and having an inlet side opposing and axially spaced from said one end of said wall memher;

a sleeve member coaxially encircling and spaced radially from said shaft and bearing means, said sleeve member being secured at one axial end thereof upon the inlet side of said impeller and extending toward and adjacent said one end of said wall member, said sleeve member and said wall member defining therewit'nin an annular inner passageway encircling said shaft and bearing means, said sleeve member and said wall member defining with said casing an annular outer passageway, rotation of said centrifugal impeller eifecting movement of gas axially along said inner passageway toward said inlet side of said centrifugal impeller and thence radially therefrom:

a plurality of axial flow blades rigidly secured upon said sleeve member at intervals around the sleeve member adjacent said wall member, said blades being spaced axially from said impeller and being arranged in said outer passageway to effect the flow of gas therealong axially away from said centrifugal impeller;

drive means for rotating said impeller and said blades around the axis of said shaft; and

annular bafile means supported upon said casing and encircling said sleeve member adjacent said impeller to direct the gas discharged by said impeller away from the gas drawn by said blades into said outer passageway.

2. The structure of claim 1 including a base member supporting said casing, racket means supporting said drive means upon said casing, coupling means connecting said drive means to said shaft for rotation thereof, and a cover member extending over said impeller and supported upon said casing, said cover member being spaced from said bafiie means.

3. The structure of claim 1 wherein the total pressure developed by the centrifugal impeller within the inner passageway adjacent the said one end of said wall member is lower than the total pressure developed by the said blades in the outer passageway adjacent the said one end of said wall member when said impeller and said blades are rotating normally, so that gas is moved from said outer passageway into said inner passageway between said sleeve and said wall member.

4. The structure of claim 1 wherein the relative locations and diameters of the adjacent end portions of said sleeve and said wall member are such that a predetermined amount of gas moves between said sleeve and said Wall member in a selected radial direction.

5. A gas moving apparatus, comprising:

an outer casing having a portion of substantially circular cross section;

a centrifugal impeller having an inlet side;

shaft and bearing means secured with respect to said casing and rotatably supporting said impeller so that said impeller is substantially coaxial with, external of, and axially spaced from one end of said portion of circular cross section, said impeller having its inlet side opposing said end of said portion and spaced from said end of said portion;

a sleeve substantially coaxial with, and secured near one end thereof to, the inlet side of said impeller, said sleeve extending from said impeller toward said casing and being coaxial with said shaft and bearing means, said sleeve defining therewithin an inner passageway, and said sleeve and said casing defining therebetween an outer passageway, rotation of said centrifugal impeller around the axis of said shaft eifecting movement of gas axially along said inner passageway toward said impeller and radially away from said impeller; and

a plurality of axial flow blades mounted upon said sleeve at intervals around the periphery thereof and spaced axially from said impeller, said blades being arranged within said outer passageway so that said rotation of said impeller causes said blades to efiect movement of gas axially along said outer passageway.

6. The structure according to claim 5 including baffle means connected to said casing and substantially encircling said sleeve adjacent said impeller to direct the gas discharged by said impeller away from the adjacent portion of said outer passageway.

7. The structure according to claim 6 wherein said sleeve extends coaxially into the adjacent end of said casing.

References Cited in the file of this patent UNITED STATES PATENTS 2,152,614 Younger Mar. 28, 1939 2,189,008 Kurth Feb. 6, 1940 2,622,858 Hughes Dec. 23, 1952 2,827,261 Parker t t. l Mar. 18, 1958

Claims

1. A GAS MOVING APPARATUS, COMPRISING: AN OUTER CASING OF SHEET MATERIAL AND CIRCULAR CROSS SECTION; AN INNER, CYLINDRICAL WALL MEMBER OF SHEET MATERIAL AND COAXIALLY DISPOSED WITHIN AND RADIALLY SPACED FROM SAID CASING; MEANS RIGIDLY SECURING SAID WALL MEMBER WITH RESPECT TO SAID CASING; A SHAFT, AND BEARING MEANS MOUNTED UPON SAID WALL MEMBER AND ROTATABLY SUPPORTING SAID SHAFT COAXIALLY WITHIN SAID WALL MEMBER, SAID SHAFT EXTENDING AXIALLY BEYOND ONE END OF SAID WALL MEMBER; A CENTRIFUGAL IMPELLER CONCENTRICALLY SUPPORTED UPON SAID SHAFT EXTERNALLY OF AND AXIALLY SPACED FROM SAID WALL MEMBER AND HAVING AN INLET SIDE OPPOSING AND AXIALLY SPACED FROM SAID ONE END OF SAID WALL MEMBER;