US3115299A - Blower damper - Google Patents

Description

1963 J. GOETTL ETAL I 3,

BLOWER DAMPER Filed March 30, 1961 1 2 Sheets-Sheet l INVENTOR.

. JOHN GOETTL M BY ALBERT B. GOETTL 38 ROBERT L. KOBLE JR.

P AT ENT AGENT Dec. 24, 1963 J. GOETTL ETAL 3,115,299

' BLOWER DAMPER Filed March so, 1961 2 Sheets-Sheet 2 INVENTOR.

JOHNGQETTL ALBERT a. GOETTL BY ROBERT L. KOBLE JR PATENT AGENT United States Patent 3,115,299 BLOWER DAMPER John Goettl, Albert E. Goettl, and Robert L. Koble, In, Phoenix, Ariz., assignors to McGraw-Edison Company, Milwaukee, Win, a corporation of Delaware Filed Mar. 30, 1961, Ser. No. 99,480 14 Claims. (Cl. 230-114) This invention relates to a blower damper and more particularly to a blower damper wherein the shutolf damper forms part of a centrifugal blower housing or is directly connected thereto to form a very compact damper structure.

Prior art blower outlet control dampers have been installed downstream of the outlets of centrifugal blowers to control the air flow therefrom. These blower outlet control dampers have been used downstream of the blower outlets of evaporative coolers and other air conditioning equipment as well as for the general control of and or shutolf of flow from the outlets of centrifugal blowers.

In evaporative coolers, for example, shutolf dampers have been placed in the outlet ducts of blowers to shutoff communication of such blowers with ducts communicating therewith. Such dampers have been conventional slide type shutoif dampers used during various seasons of the year for shutting off communication of the air conditioning ducts with an evaporative cooler blower. In many instances these dampers prevent the escape of hot air from the ducts through the evaporative cooler blower during the winter time and such dampers may be opened during the summer time to permit flow of cool air from the evaporative cooler blower into the ducts.

In many locations such shutoff dampers are difficult to operate or install and in such confined structures as evaporative coolers conventional blower shut off dampers cannot be conveniently installed due to space limitations.

In evaporative coolers the blower housing structure is ordinarily surrounded by adjacent walls or evaporative cooler pads and there is not suflicient room between the blower and the walls or pads to accommodate the retraction of a damper of sufiiceint cross-sectional area to completely shutoff or cover the blower outlet opening.

Accordingly, it is an object of the invention to provide a blower outlet damper mechanism which is adapted to shutoff or vary the blower outlet area of a blower and wherein this damper mechanism is adapted to follow or substantially conform to the curvature of the blower housing so that it is very compact and readily operable within confined spaces where a blower may be installed.

Another object of the invention is to provide a blower outlet damper mechanism which is slidable around the curved wall or portion of a centrifugal blower and project- -ab1e across the outlet opening of a centrifugal blower to shutoff and or control the flow from the blower.

Another object of the invention is to provide a blower damper which is slidable about a curved portion of a centrifugal blower housing and forms a portion of the curved wall thereof whereby the damper when slidably moved around the curved portion of the blower housing and projected across the blower outlet opening to close the same, provides an access opening in the curved wall of the blower housing so that the blower wheel internally of the housing may be readily cleaned or serviced through said access opening.

Another object of the invention is to provide a blower damper having very compact mechanism operable within confined space internally of the evaporative coolers or the like.

Another object of the invention is to provide a blower damper comprising a flexible sheet of material adapted 3,115,299 Patented Dec. 24, 1963 to slide around the curvature of a blower housing and having an inner edge normally disposed to serve as a blower cutoll when said damper isv in open position and projectable to shutofl the outlet of said blower when said damper is in closed position.

Another object of the invention is to provide a blower damper having a flexible plate slidable around a curved side wall of a centrifugal blower and projectable into the outlet of said blower for shutting off the fiow therefrom whereby slidable movement of said plate exposes an open area in the curved side wall of the blower housing and whereby another flexible curved plate is slidable in the opposite direction around said housing to expose an additional opening in the curved blower housing so that the combined opening exposed by both of said plates is sulficient to permit removal of the blower wheel from the housing through the combined opening.

Another object of the invention is to provide a blower outlet damper usable in connection with centrifugal blowers wherein the damper is a flexible plate slidable around the curved surface of a centrifugal blower and having an inner edge project-able across the outlet opening of the blower; said damper member having a gear rack means thereon; and a spur gear mechanism meshing with said rack means and disposed to acutate said damper into and out of closed position with respect to the outlet opening of said blower.

Further objects and advantages of the invention may be apparent from the following specification, appended claims and accompanying drawings in which:

FIG. 1 is a side elevational view of an evaporative cooler showing a blower therein and installed on the roof of a building and showing portions broken away and in section to amplify the illustration;

FIG. 2 is a fragmentary sectional view taken from the line 22 of FIG. 1;

FIG. 3 is an enlarged fragmentary sectional view taken from the line -33 of FIG. 2;

FIG. 4 is an enlarged fragmentary sectional view taken from the line 4-4 of FIG. 2;

FIG. 5 is a fragmentary sectional view taken from the line 55 of FIG. 4;

FIG. 6 is a fragmentary sectional View taken cfrom the line 66 of FIG. 4;

FIG. 7 is a fragmentary side elevational view of a modified form of the invention showing a blower and blower damper and portions of the blower housing in section and illustrating by arrows the direction of movement of the damper about the curved structure of the blower housing;

FIG. 8 is a fragmentary sectional view taken from the line 3-8 of FIG. 7;

FIG. 9 is a view similar to FIG. 7 but showing a further modified form of the blower damper in accordance with the present invention;

FIG. 10 is another view similar to FIG. 7 but showing an additional modification of the invention;

FIG. 11 is another view similar to FIG. 7 showing a further modification on an enlarged scale and illustrating a rack and pinion mechanism for movement of the damper with respect to the blower housing; and

FIG. 12 is a fragmentary sectional view taken from the line 12-12 of FIG. 11.

As shown in FIG. 1 of the drawings, the blower damper of the invention is disclosed in connection with a blower internally of an evaporative cooler which is located on the roof of a building. The damper of the present invention is thus disclosed to illustrate one advantageous installation application thereof.

As shown in FIG. 1, an evaporative cooler 14 is mounted on a building roof 16 having a duct 18 extending upwardly therethrough to the outlet 20 of a blower 22 is internally of the evaporative cooler 14. The evaporative cooler 14 is provided with side walls 24 having evaporative cooler pads 26 therein. These evaporative cooler pads 26 are closely adjacent the blower 22 and normally there is not sufficient distance between the extremities of the outlet 20 and any one of the evaporative cooler pads 26 for slidably actuating a conventional damper to shut off the outlet 26 of the blower 22. This blower 22 is a conventional centrifugal blower having the usual eccentrically mounted rotor 28 therein discharging through a substantially tangential outlet 20 of the blower housing.

Conventional centrifugal blowers of this type are usually provided with a flow cutoff normally located at 3i). This structure at 34 shown in FIG. 1 of the drawings is a rolled edge 32 of a shutoff damper according to the present invention. This rolled edge 32 serves two purposes, namely as a blower cutofl and as a shutoff edge of a slidable damper member 34 which is disposed to shutoff the blower outlet Ztl and prevent flow outwardly from the blower in the direction of the arrows A in FIG. 1 of the drawings. As shown in FIGS. 1 and 5 of the drawings, the damper member 34 is a thin flexible sheet of metal having its opposite edges disposed in channel shaped guides on guide channels 36 supported on opposite inner side walls of the blower outlet 20. These guide channels 36 support opposite edges 38 of the damper member 34 so that the damper member 34 may be transformed from an arcuate shape to a straight flat shape when moved from open position as shown by solid lines in FIG. 1 to a damper closed position shown by broken lines in FIG. 1.

As shown in FIGS. 1 and 6 of the drawings, opposite side walls 46 of the blower housing are provided with inwardly directed flanges 42 forming guides extending inwardly of the opposite edges 33 of the damper member 34 so that the damper member 34- when in the solid line position shown in FIG. 1 of the drawings is retained in a curved or arcuate shape adjacent the arcuate or curved flanges 42 which are integral with the opposite side walls 40 of the blower housing.

Inwardly of the damper member 34 adjacent the curved flanges 42 are annular in cross section guide spools 44 held to the side walls 40 by means of screws 46. These guide spools 44 may be made of nylon or other suitable material and their peripheral portions are slightly spaced from the inwardly directed flanges 42 so that the damper member 34 may be disposed between the guide spools 44 and the guide flanges 42. Thus, the damper 34!- is provided with a guide means at its op osite ends including the curved flanges 42 and corresponding guide spools 4d. The damper member 3 5 at its edge opposite to the rolled edge 32 is provided with a clip edge 48 which is substantially channel shaped in cross section. This clip edge 48 is retained in a clip detent which is integral with an arcuate or curved wall 52 of the blower housing.

As shown in detail in FIG. 3 of the drawings, the clip edge 48 is retained and held by the clip detent portion d of the curved wall portion 52 of the blower housing and it will be understood that the clip detent St is resilient so that it may be sprung outwardly in the direction of the arrow B in FIG. 3 of the drawings to permit a release of the clip 43 therefrom so that the damper member 34 may be moved in the direction of the arrow C in FIG. 3 of the drawings.

A cup shaped recess member 54 is located in the damper member 34 and it is spot welded thereto providing a recess in which a person may place his fingers to apply force to the damper member in the direction of the arrow C or in the opposite direction depending upon whether it is desired to move the damper to closed or open positions, respectively.

As shown in FIGS. 4 and 5 of the drawings, the duct 18 is provided with a conventional outwardly extending flange 56 surrounded by a resilient gasket 58 the upper surface of which is engaged by a flange till surrounding the outlet of the blower. Clips 62 are folded under a lower portion 64 of the gasket 58 to retain the blower housing securely connected in sealed relationship with the flange 56 of the duct 18.

As shown in FIG. 1 of the drawings, it will be seen that during operation of the blower 22 the damper 34 may be maintained in the solid line position for a normal blower operation wherein the curled edge 32, of the damper 34 acts as conventional blower cutoff at the outlet thereof.

When it is desired to shut ofl or partially shut oil the outlet of the blower the detent clip 50 may be sprung outwardly in the direction of the arrow B while force is exerted in the recess 54 of the damper member 34 in the direction of the arrow C until the clip portion 43 is released from the detent clip Sil. The damper 34 is then slidably projected around the inner surfaces of the guide flanges 42 hereinbefore described and inwardly of the guide spools 4-4 until the rolled edge 32 is projected to a desired position either to partially close the outlet 2 of the blower or completely to close the outlet of the blower as indicated by broken lines D. The roller edge 32 of the damper member 34 when engaged with the outlet side wall 33 completely closes the outlet Zil.

It will be appreciated that the hereinbefore described channel members 36 at opposite sides 4% of the blower housing are straight and disposed substantiall tangentially of the curved portion of the damper and/ or a curved wall of the blower housing and tend to transform the damper member 34 from a curved disposition, as shown by solid lines, to a straight disposition as shown by broken lines in FIG. 1 of the drawings.

It will be understood that this damper member 34 is preferably of flexible and or resilient material capable of being deflected into conforming relationship with curvature of the blower housing whereby the retraction of the damper member 34 into an open damper position does not interfere with the side walls of an evaporative cooler or any other surrounding structure but merely follows the curvature of the blower housing side wall and thereby provides a blower damper which is capable of fully shutting oil the entire cross sectional area of the blower outlet without consuming substantially more space than the blower itself occupies.

In the modification as shown in FIG. 7 of the drawings, the damper member 34 at its curled edge 32 is structurally similar to that shown in FIG. 1 of the drawings, however, the damper member 34 as shown in FIG. 7 of the drawings, is provided with a handle 66 which is fixed thereto and which projects outwardly through a slot 68 in the curved wall or portion 52 of the blower housing. Thus, when the handle as is projected from the solid line position, shown in FlGS. 7 and 8 to the broken line position shown therein, the damper member 34 is projected from an open damper position into a closed damper position.

Guide spools 44 are provide to guide the damper member 34 while guide channels 38, similar to the guide chan nels 38 shown in FIG. 5 of the drawings, are provided to guide opposite edges of the damper member 34 into a straight line condition across the outlet of the blower 22.

It will be seen that the damper member 34 as shown in FIG. 7 of the drawing, is disposed inwardly of the arcuate wall or portion 5 2 of the blower housing.

Actually the wall 52 may be arcuate or may be an irregularly curved shape, however, for all practical purposes of description this wall will be referred to as a substantial arcuate or curved wall. Thus, it will be understood that the wall 52 provides a curved guide for the damper member 34 at its outer surface and different from the damper 34 shown in FIG. 1 in that the structure shown in FIG. 1 utilizes the curved flanges 42 to provide an outer support for the damper 34.

In the modification as shown in FIG. 9, the blower 22 is provided with a conventional blower cutofi 7t and a damper structure 72 is operable separately from the cutoff structure '70. This damper "72 is a sheet of flexible metal or other equivalent material and when in open position is disposed in curved form around the curved wall 52 of the blower housing 22, and when in closed position is projected across the entire cross sectional area of the blower outlet 29 in a similar manner to the disposition of the damper 34 shown in FIGS. 1 and 7 of the drawings.

This damper 72 at its opposite edges is supported in guide channels 38 secured to opposite inner side Walls of the blower housing as hereinbefore described. The damper member 72 adjacent the cunved wall 52. of the blower housing is supported in curved guide channels 74 which are secured by spot welding 75 to opposite sides 4% of the blower housing.

It will be seen that the damper member 72 is provided with an inner edge 76 which corresponds to the rolled edge 32 of the damper member 34. This edge 76 when disposed adjacent the wall 33 of the blower housing provides for complete shutoif of the flow outwardly through the blower outlet 2%. When the edge 76 is adjacent the wall 33 a damper actuating handle 78 is disposed in a broken line position F all as shown best in FIG. 9 of the drawings.

In the modification as shown in FIG. 10 of the drawings, the structure of the damper 34 is identical to that as shown in FIG. 1 of the drawings, however, the clip detent St is integral with a curved sliding section Sit of the blower housing. This section 89 replaces a short section of the curved side wall 52 whereby the section 80 is slidable to a broken line position G. Thus, the section 89 when moved to the broken line position G, and the damper 34 when moved to the broken line position as shown in FIG. 1 of the drawings, exposes a combined opening in the side of the blower housing sufliciently large for the removal of the blower wheel.

The section 84) is guided internally of the curved wall 52 of the blower housing by guide spools 44 secured to the end walls 4% of the blower housing in a similar manner to the guidance of the damper member 34 shown in FIG. 1 of the drawings.

It will be understood that operation of all of the dampers 34 and 72, as disclosed herein, may expose an opening in the side wall of the curved wall or curved portion of the blower housing when these dampers are in shut off position whereby, access to the blower may be had through the opening in the arcuate wall of the housing in order to clean the blower wheel without the necessity of removing it from the blower housing.

In the modification as shown in FIGS. 11 and 12 of the drawings, a blower damper member 82 is provided with corrugated gear rack portions 84 at its opposite edges with which pinion gears 86 mesh. These pinion gears 86 are mounted on shafts 88 supported in bearings 90 secured to the side wall portions 40 of the blower housing. Secured to these shafts 88 are handles 92 which are provided for rotation of the shafts 88 together with the pinions 86 to move the corrugated rack portions 84 and the damper member 82 slidably around the curved side wall portion 2 of the housing as hereinbefore described.

It will be appreciated that the damper 82 may be supported and guided in a manner similar to the hereinbefore described damper 34 and that various means may be substituted for the handle 92, for example, any power means may be connected thereto for actuating the damper 82.

The damper 82, as shown in FIGS. 11 and 12, it supported at its outermost corrugated rack edges by the flanges 42 integral with the side walls 4%} of the blower housing and guide spools 44 operate to support this damper member 82 in a similar fashion to the operation of the guide spools 44 adjacent the damper member 34.

It will be obvious to those skilled in the art that various modifications of the present invention may be resorted to in a manner limited only by a just interpretation of the following claims.

We claim:

1. In a blower damper the combination of: a blower housing; a blower rotor therein; an outlet portion of said blower housing disposed to conduct flow from said rotor; a flexible damper means disposed slidably across said outlet portion of said blower and adapted to shut ofl? flow therethrough; a curved portion of said blower housing adjacent said outlet portion; a portion of said flexible damper means disposed in substantially curved conformity with said curved portion of said housing; and substantially straight guide means disposed substantially tangentially with respect to said curved portion of said blower housing to guide the movement of said flexible damper means across said outlet portion of said blower; and to guide said portion of said flexible damper means around the curved portion of said blower housing, said curved portion of said blower housing having an opening therein; said portion of said flexible damper disposed to expose said opening when said flexible damper is projected across the outlet portion of said blower housing, said portion of said damper means being disposed to close said opening in said curved portion of said blower housing when said flexible damper means is retracted out of interference with flow passing through said outlet portion of said blower housing.

2. In a blower damper the combination of: a blower housing; a blower rotor therein; an outlet portion of said blower housing disposed to conduct flow from said rotor; a flexible damper means disposed slidably across said outlet portion of said blower and adapted to shut off flow therethrough; a curved portion of said blower housing adjacent said outlet portion; a portion of said flexible damper means disposed in substantially curved conformity with said curved portion of said housing; and substantially straight guide means disposed substantially tangentially with respect to said curved portion of said blower housing to guide the movement of said flexible damper means across said outlet portion of said blower; and to guide said portion of said flexible damper means around the curved portion of said blower housing, said curved portion of said blower housing having an opening therein; said portion of said flexible damper disposed to expose said opening when said flexible damper is projected across the outlet portion of said blower housing, said portion of said damper means being disposed to close a first portion of said opening in said curved portion of said blower housing when said flexible damper means is retracted out of interference with flow passing through said outlet portion of said blower housing, said curved portion of said blower housing having a curved wall portion slidably positioned over a second portion of said opening in said curved portion, said curved wall portion slidable in the opposite direction around said curved portion of said housing :from the sliding direction of said flexible damper means when projected across said blower housing outlet portion whereby said curved wall and said flexible damper means may be retracted away from each other around the curved portion of said blower housing to expose the entire area of said opening therein providing for access to said rotor and the removal of the same through said opening in said curved portion of said blower housing.

3. In a blower damper the combination of: a blower housing; a blower rotor therein; an outlet portion of said blower housing disposed to conduct flow from said rotor; a flexible damper means disposed slidably across said outlet portion of said blower and adapted to shut ofl flow therethrough; a curved portion of said blower housing adjacent said outlet portion of said flexible damper means disposed in substantially curved conformity with said curved portion of said housing; and substantially straight guide means disposed substantially tangent to said curved portion of said blower housing and disposed to guide the movement of said flexible damper means across said outlet portion of said blower and to guide said portion of said flexible damper means around the curved portion of said blower housing, said curved portion of said blower housing having an opening therein; said portion of said flexible damper disposed to expose said opening when said flexible damper is projected across the outlet portion of said blower housing, said portion of said damper means being disposed to close a first portion of said opening in said curved portion of said blower housing when said flexible damper means is retracted out of interference with flow passing through said outlet portion of said blower housing, said curved portion of said blower housing having a curved wall portion slidably positioned over a second portion of said opening in said curved portion, said curved wall portion slidable in the opposite direction around said curved portion of said housing from the sliding direc tion of said flexible damper means when projected across said blower housing outlet portion whereby said curved wall and said flexible damper means may be retracted away from each other around the curved portion of said blower housing to expose the entire area of said opening therein providing for access to said rotor and the removal of the same through said opening in said curved portion of said blower housing; means releasably coupling adjacent portions of said flexible damper means and said curved wall portion to retain the same in position to cover said opening in said curved portion of said blower housing.

4. In a blower damper the combination of: a blower housing; a blower rotor therein; an outlet portion of said blower housing disposed to conduct flow from said rotor; a flexible damper means disposed slidably across said outlet portion of said blower and adapted to shut ofl" flow therethrough; a curved portion of said blower housing adjacent said outlet portion; a portion of said flexible damper means disposed in substantially curved conformity with said curved portion of said housing; and substantially straight guide means disposed substantially tangentially with respect to said curved portion of said blower housing to guide the movement of said flexible damper means in progressing from a flat configuration toward a relatively curved configuration in moving across said outlet portion of said blower; and further guide structure disposed to guide said portion of said flexible damper means around said curved portion of said blower housing; said damper operable relative to said guide means and projectable along said damper guide means across the area of said outlet to a closed shut off position to shut off flow therethrough; and an edge portion of said damper disposed at said blower outlet and, said edge when retracted out of closed shut off position disposed and serving as a blower cut off.

5. A centrifugal blower having a volute housing and an outlet port in said housing, said port being in a plane substantially tangent to said housing, said volute housing having at least one axially located inlet, a rotor mounted in said housing and adapted to draw fluid through said inlet and move said fluid centrifugally through said port, a flexible damper disposed to be moved across said port and having a portion to be flexibly curved to conform to said housing curvature and a portion extending from said curved portion to be flexed into generally flat configuration in being moved across said port, means for guiding said damper from curved to flat condition in moving across said port in said generally fiat configuration.

6. A blower as set forth in claim 5, said flexible damper having an edge movable into the fluid flow from said rotor as said damper is moved across said port, so as to divide said flow into a predetermined discharge portion through said port and into a portion for recirculation by said rotor, said flexible damper being movable to an extent to fully shut off said port from discharge.

7. A blower as set forth in claim 5, said guide means comprising straight and curved portions for guiding said flexible damper from a curved condition to a relatively flatter condition in moving across said port, said curved portion being within said housing and said straight portion being generally coplanar with said port, one end portion of said flexible damper being curved to conform with the curvature of said housing at all times and another end portion being in relatively flatter condition at all times.

8. A blower as set forth in claim 5, said damper having an edge disposed to move in a plane generally tangent to the volute housing at substantially least radius of said housing with respect to the axis of said rotor.

9. In a blower damper the combination of: a blower housing; a blower rotor therein; an outlet portion of said blower housing disposed to conduct flow from said rotor; a flexible damper means disposed slidably across said outlet portion of said blower and adapted to shut off flow therethrough; a curved portion of said blower housing adjacent said outlet portion; a portion of said flexible damper means disposed in substantially curved conformity with said curved portion of said housing; substantially straight guide means disposed substantially tangentially with respect to said curved portion of said blower housing to guide the movement of said flexible damper means across said outlet portion of said blower; and curved guide structure to guide said portion of said flexible damper means around the curved portion of said blower housing; said flexible damper having an edge portion forming a flow cut-ofl adjacent said rotor.

10. A centrifugal blower as set forth in claim 5, said housing having a slot and a handle element extending therethrough and secured to said damper whereby said damper may be moved by means of said handle across said port.

11. A centrifugal blower as set forth in claim 5, said damper being provided with corrugations, and a gear carried by said housing and mounted for rotation to drive said damper across said port.

12. A centrifugal blower as set forth in'claim 5, said damper being disposed on the exterior of said housing and said housing having an opening adjacent said port through which a portion of said damper extends.

13. A centrifugal blower as set forth in claim 5, said housing having an opening in the side thereof sufficiently large for removal of the rotor therethrough and having a closure section for said opening, and means for slidably guiding said closure section with respect to said housing to partially expose said opening, and means for removably securing said section to said damper whereby said section and said damper together fully close said opening but may be separated and moved in opposite directions to substantially fully expose said opening.

14. A centrifugal blower as set forth in claim 5, said damper forming a portion of the wall of sad housing when said port is open and effecting an opening in said wall in moving toward closure of said port.

References Cited in the file of this patent UNITED STATES PATENTS 284,279 Cockson Sept. 4, 1883 823,637 Prame June 19, 1906- 829404 Kime Aug. 28, 1906 874,329 Gray Dec. 17, 1907 2,298,745 Klockau Oct. 13, 1942 2,316,224 DElia Apr. 13, 1943 2,656,095 Campbell Oct. 20, 1953 FOREIGN PATENTS 26,130 Great Britain Nov. 19, 1906 65,083 Denmark Nov. 18, 1946

Claims (1)

1. IN A BLOWER DAMPER THE COMBINATION OF: A BLOWER HOUSING: A BLOWER ROTOR THEREIN; AN OUTLET PORTION OF SAID BLOWER HOUSING DISPOSED TO CONDUCT FLOW FROM SAID ROTOR; A FLEXIBLE DAMPER MEANS DISPOSED SLIDABLY ACROSS SAID OUTLET PORTION OF SAID BLOWER AND ADAPTED TO SHUT OFF FLOW THERETHROUGH; A CURVED PORTION OF SAID BLOWER HOUSING ADJACENT SAID OUTLET PORTION; A PORTION OF SAID FLEXIBLE DAMPER MEANS DISPOSED IN SUBSTANTIALLY CURVED CONFORMITY WITH SAID CURVED PORTION OF SAID HOUSING; AND SUBSTANTIALLY STRAIGHT GUIDE MEANS DISPOSED SUBSTANTIALLY TANGENTIALLY WITH RESPECT TO SAID CURVED PORTION OF SAID BLOWER HOUSING TO GUIDE THE MOVEMENT OF SAID FLEXIBLE DAMPER MEANS ACROSS SAID OUTLET PORTION OF SAID BLOWER; AND TO GUIDE SAID PORTION OF SAID FLEXIBLE DAMPER MEANS AROUND THE CURVED PORTION OF SAID BLOWER HOUSING, SAID CURVED PORTION OF SAID BLOWER HOUSING HAVING AN OPENING THEREIN; SAID PORTION OF SAID FLEXIBLE DAMPER DISPOSED TO EXPOSE SAID OPENING WHEN SAID FLEXIBLE DAMPER IS PROJECTED ACROSS THE OUTLET PORTION OF SAID BLOWER HOUSING, SAID PORTION OF SAID DAMPER MEANS BEING DISPOSED TO CLOSE SAID OPENING IN SAID CURVED PORTION OF SAID BLOWER HOUSING WHEN SAID FLEXIBLE DAMPER MEANS IS RETRACTED OUT OF INTERFERENCE WITH FLOW PASSING THROUGH SAID OUTLET PORTION OF SAID BLOWER HOUSING.

Images