US3273632A

US3273632A - Fire damper

Info

Publication number: US3273632A
Authority: US
Publication date: 1966-09-20
Anticipated expiration: 1983-09-20

Description

F. J. M CABE Sept. 20, 1966 FIRE DAMPER 5 Sheets-Sheet 1 Filed June 17, 1964 INVENTOR.

FRANCIS J. Mc CABE ATTORNEY Se t. 20, 1966 F. J. M CABE 3,273,632

FIRE DAMPER Filed June 17, 1964 5 Sheets-Sheet 2 54 W l. I

I W l:

I I v :3 INVENTOR. o 49 BY FRANCIS J. McCABE 4e moms/s. 2W4

ATTORNEY F. J. M CABE FIRE DAMPER Sept. 20, 1966 5 Sheets-Sheet 3 Filed June 17, 1964 TOR.

' FRANCIS J. MCCABE WWW ATTORNEY Sept. 20, 1956 cc 3,273,632

FIRE DAMPER Filed June 17, 1964 5 Sheets-Sheet 5 Figs i4 F79. l5

89 INVENTOR.

FRANCIS J MCCABE ATTORNEY instant invention.

United States Patent "ice 3,273,632 FIRE DAMPER Francis J. McCabe, Penns Park, Pa., assignor to Air Balance Inc., Philadelphia, Pa., a corporatlon of Pennsylvania Filed June 17, 1964, Ser. No. 375,855 17 Claims. (Cl. 160-1) This invention relates generally to fire damper constructions, and more particularly, relates to automatically actuated fire damper structures adapted for installation in air delivery systems such as duct structures and which include a plurality of hingedly interfitted metal slats of novel configuration which afford easy relative rotation between adjacent slats without binding.

In the past, fire dampers or fire shutters have been designed for the same general purpose as that of the However, the hinging structures of the slats utilized in such known devices have taken the form of interfitted circular arcs, or interfitted identical spirals, neither of which configurations permit 180 relative rotation between adjacent slats of the composite damper structures. Consequently, the slat structures can not be compactly reversely folded against one another to form a small and unobstrusive structure. In contrast to these known types of devices, the fire damper construction according to the instant invention utilizes a hinging configuration of irregular shape which permits substantially 180 rotation of adjacent slats and thereby makes possible an extremely compact slat assembly which occupies a minimum of space. Accordingly, it is a primary object of this invention to provide a novel fire damper slat or blade having parallel spaced apart longitudinally extending edges each of which is differently formed but complemental to the other to provide one half of a blade hinging structure in which one of the edges may he slipped endwise into the complementally formed edge on another blade of the type formed at its own opposite longitudinally extending edge, each of the half hinge edges including curved and straight regions which conjointly function to provide substantially 180 relative rotation between adja cent hinged together blades without blade binding or any tendency toward blade disengagement, the center of rotation of the composite hinge structure being spaced laterally from the centroid thereof.

Another object of my invention is to provide a novel damper construction in which the rotation of the damper slats to effect closing of the damper unit is carried out by positively acting drive means automatically rendered operative by a predetermined temperature condition in the region of the fire damper.

A further object of my invention is to provide a novel fire damper structure which is fabricated in modular form so that it may be utilized with different types of mounting flange configurations securable thereto.

Yet another object of my invention is to provide a novel fire damper slat construction, and complete fire damper assemblies utilizing such novel slat, wherein the slat hinging configuration is characterized by an axis of rotation which is generally disposed laterally of the main plane of the slat.

The foregoing and other objects of my invention will become clear from a reading of the following specification in conjunction with an examination of the appended drawings, wherein:

FIGURE 1 is a front elevational view of a fire damper structure according to the invention with the right hand portion broken away, the damper structure being illustrated with the blades in compact folded form to permit passage of air therethrough;

FIGURE 2 is a vertical cross sectional view through Patented Sept. 20, 1966 the damper construction of FIGURE 1 as would be seen when viewed along the line 22 thereof, phantom showings being also illustrated as designating the positions of the damper blades when the latter have been vertically expanded to close the damper opening;

FIGURE 3 is a horizontal cross-sectional view taken through the fire damper structure of FIGURE 1 as would be seen when viewed along the line 3-3 thereof;

FIGURE 4 is a front elevational view of the fire damper of FIGURE 1 modified to illustrate the damper blades in vertically opened out position as would be seen when the damper structure has been actuated to cut off air flow therethrough;

FIGURE 5 is a horizontal cross-sectional view through the damper structure of FIGURE 4 as would be seen when viewed along the line 5-5 thereof;

FIGURE 6 is a modified form of fire damper structure in which the damper blades are compacted upward into a hat structure to remove the same from the air flow path through an air duct structure illustrated in phantom, the fire damper structure being shown in perspective with portions broken away to reveal constructional details thereof;

FIGURE 7 is an enlarged fragmentary vertical crosssectional view through the upper portion of the modified form of fire damper shown in FIGURE 6;

FIGURE 8 is a perspective showing somewhat similar to that of FIGURE 6 but in which the damper blades have dropped as a curtain to block air flow through the damper and duct structure;

FIGURE 9 is a perspective view of a modified form of fire damper construction similar to that of FIGURE 6 but in which the damper unit is disposed completely within a duct structure and is not provided with the top cap construction;

FIGURE 10 is a plan view of another modified form of fire damper intended for disposition in a horizontal plane to close a vertically extending air passage when actuated;

FIGURES 11 and 12 are vertical sectional views, on an enlarged scale, taken through the modified form of fire damper shown in FIGURE 10 as would be seen when viewed along the lines 1111 and 1212, FIG- URE 11 representing the damper when open while F-IG- URE 12 represents the damper with the blades opened out in damper closing position;

FIGURE 13 is an end elevational view of one of the damper blades shown on an enlarged scale illustrating the asymmetric configuration of the half hinge configuration formed at the opposite parallel longitudinally extending blade edges;

FIGURES 14 through 19 illustrate on an enlarged scale a pair of hingedly interfitted damper blades at successive points of relative rotation corresponding to fully compacted to fully expanded conditions of the damper blades.

In the several figures, like elements are denoted by like reference characters.

Considering first FIGURES 1 through 5, it is observed that the fire damper structure includes a frame assembly designated generally as 30 which carries a blade assembly designated generally as 31. The frame assembly includes a top member 32 and bottom member 33, a pair of identical opposite side frame members 34 rigidly secured at their upper and lower ends to the top frame member 32 and bottom frame member 33 as by welding to thereby form a fixed rectangular frame. The top and

bottom frame members

32 and 33, as best seen in FIGURE 2, are of the same cross-sectional configuration and are arranged in the frame assembly as mirror images, these members being formed of sheet metal stock convoluted to form a central width-wise extending channel defined by sloping side walls and a pair of flanking widthwise extending front and/or back channels of generally rectangular cross-section.

The central channel of the bottom frame member 33 is defined by the divergingly upwardly extending wall portions 35 while the front aud/ or rear flanking rectangular channels are defined by the orthogonally disposed

wall portions

36, 37 and 38, the upper ends of the wall portions 38 being turned horizontally inward toward one another in partially overlying relationship to the wall portions 37 to provide flanges 39. Since the top member 32 is exactly the same in cross-sectional shape as the bottom frame member 33 and differs from the latter only in that it is oriented in inverted position, the corresponding Walls and flanges of the top frame member 32 are designated by the same corresponding reference characters to those utilized for the frame bottom member. That is, the wall portions are designated by the numerals 35 through 38 and the flanges are designated 39. The sloping side wall portions 35 of the top and

bottom frame members

32 and 33 respectively act as guides or lead-ins for the ends of the upper and lower terminal edges of the damper blades to prevent wedging or jamming thereof when the blades are expanded to opened out form to close the cross-section of the fire damper, the disposition of the upper edge of the upper blade and the lower edge of the lower blade being as illustrated in phantom in the showing of FIGURE 2.

The side frame members 34 are each formed from a pair of vertically extending parts of constant cross-sect-ion of the form best seen in the showings of FIGURES 3 and with these side frame member parts being designated generally as 40 and 41. The part 40 is formed from a piece of rectangular sheet metal stock having its long side edges turned in the same direction at right angles to the main plane of the stock to form corner flanges 42, and the vertically extending central region of the main planar portion is folded forward in the same direction as the corners 42 to form the vertically centrally extending U-shaped channel 43 having side walls parallel to the corner flanges 42 and a connecting wall parallel to the main plane of the member 40. The side frame member part 41 is a vertically extending sheet metal part formed into a U-shaped channel member having a laterally outwardly turned flange extending from the upper end of each of the channel side wall portions, which flanges are seated flat-wise against the inside surface of the side frame member part 40 on opposite sides of the channel portion 43 of the latter, and the bottom wall of the U- shaped channel part 41 is seated against the bottom wall of the U-shaped channel, part 43 of the side frame member part 40. The

frame parts

40 and 41 are fixedly secured together, as by spot welding, along their engaged surfaces.

The U-shaped channel part 41 of the side frame member is shorter in length than the side frame part 40 and terminates at points above the lower edge and below the upper edge of the latter, so that the top and

bottom frame members

32 and 33 are disposed respectively below and above the channel part 41 and in end abutment with the side frame member parts 40. The upper and lower ends of the side frame part 41 engage respectively the junction of the

walls

35 and 36 of the top and

bottom frame members

32 and 33 while the opposite ends of the top and bottom frame members are close fittingly disposed between the corner flanges 42 of the side frame member part 40.

It is observed that the frame assembly may be inverted top for bottom without in any manner-changing its appearance, so that while the top frame member 32 functions as a head member and the bottom frame member 33 functions as a sill member, the head and sill members are in fact interchangeable since they are indistinguishable and the fire damper assembly therefore has no real top or bottom. The bottom channel wall of the U-shaped channel member 41 of the side frame members 34 functions, as will be subsequently seen, as a blade guide and will be so referred to hereinafter, Before considering the blade assembly 31 in detail attention should be directed to the blade follower mechanism carried by the frame assembly, the details thereof being most clearly observed in the showings of FIGURES 2, 3 and 5.

Each of the blade follower assemblies situated at the opposite side edges of the frame assembly includes a pair of blade follower elements 44 extending vertically between the top and bottom flanges 39 of the head and

sill members

32 and 33, and a pair of blade follower closure coil springs 45. The blade follower elements 44 are each formed from a piece of rectangular sheet metal having one longitudinally extending vertical edge rolled into a loop as at 46, and having its other longitudinally extending vertical edge turned at approximately a right angle to the main plane of the blade follower and folded back upon itself to form a reinforced bearing edge 47 which abuts the hinged edges of the blade assembly 31 in the manner illustrated in FIGURES 2 and 3. Each of the blade followers 44 is secured for swinging motion about a vertical pivotal axis by means of the pivot pins 48 extended through the head and sill flanges 39 into the rolled loops 46 formed at one edge of the blade follower as previously described.

The closure coil springs are each formed with a pair of end loops 49 rolled outward away from one another to provide a fairly flat intermediate portion 50 which is riveted or otherwise fixedly secured as at 51 to the outside of the side frame member part 40. The natural roll of the spring loops 49 tries to move the loops toward one another so that they each bear against the outside surface of one of the blade follower elements 44 to force the reinforced bearing edges 47 against the blade assembly 31 as seen in FIGURES 2 and 3. When the blade assembly opens out in the manner shown in FIG- URES 4 and 5, the spring loops 49 of the closure springs 43 swing the blade follower elements 44 about their pivot pins 48 to drive the reinforced bearing edges 47 inward into engagement with the blade guide face of the U-shaped channel element 41 forming part of the side frame members 44 to thereby lock the blades of the assembly 31 in their vertically opened out position and insure that the opening through the fire damper frame assembly remains completely closed.

Consider now the blade assembly 31 illustrated in FIGURES 2 and 4 as comprising five individual damper blades pivotally connected together along parallel horizontally oriented longitudinally extending edges, the blades being designated from top to bottom in the assembly as blades 52 through 56. All of the blades are of the same length and have their opposite ends disposed in close proximity to the blade guide faces of the side frame U-shaped channels 41, the center blade 54 having secured thereto a pivot pin 57 at each end of the blade with the pivot pin projected freely rotatably through the blade guide face of the side frame channel member 41 and base of the U-shaped channel portion 43 of the side frame member 40. This pivot pin arrangement, of course, supports the entire blade assembly 31 from the side frame members 34 of the frame assembly 30, the blades 52 through 56 being secured together in central position by means of the cinch cable 58 wrapped thereabout and secured by a fire link 59.

The fire link 59 is formed from a pair of metal plates held together by a low temperature fuse metal chosen to melt at a desired temperature. Disposed between the

blades

52 and 53 and fixedly secured to one of them, and also disposed between the blades 54 and and fixedly secured to one of these are generally C-shaped actuating springs 60 illustrated in the showing of FIGURE 2 in their compressed form and held in such state by the cinch cable 58 and fire link 59. When the fuse metal of the fire link 59 melts, thus relieving the restraint upon the acdrive the damper blades away from one another both upwardly and downwardly by a suflicient amount to allow the closure coil springs 45 to swing the blade follower elements 44 inward into positions where the latter develop sufficient torque on the blades to completely drive the latter into the vertically disposed condition shown I in FIGURES 4 and 5.

As best seen in FIGURE 4, the hinging structure of the damper blades is such that air blowing against the plane of the damper assembly cannot pass therethrough. Moreover, as is most clearly seen in FIGURE 5, the vertically extending position of the reinforced bearing edges 47 of the blade follower elements 44 is such as to close the small opening between the blade guide face of the side frame member 41 and the ends of the blades 52 through 56 so that the actuated or closed damper is for all real purposes substantially air tight. From FIGURES l and 4 it is observed that the blade assembly 31 is approximately centered in the frame assembly 30 and that closure coil springs 45 are spaced above and below the blade assembly at each side thereof. Other arrangements are of course possible, as for example, the blade assembly 31 may be pivoted at a vertically higher point in the frame assembly by merely securing the pivot pin structures 57 to damper blade 53 instead of blade 54.

Before considering in detail the novel damper blade structure as shown in FIGURE 13 and the method of operation as illustrated in FIGURES 14 through 19, attention should be directed to the damper structure modifications shown in FIGURES 6 through 12 since all forms of the dampers utilize the same novel damper blade in the same manner. Consider first FIGURES 6, 7 and 8 which illustrate a gravity operated vertical-drop fire damper structure providing a substantially unobstructed air flow cross-section through a duct system. The damper assembly includes a frame assembly designated generally as 61, a blade assembly designated generally as 62, and a mounting assembly designated generally as 63.

The frame assembly 61 is formed from four lengths of channel stock arranged in a rectangle with the flanges presenting toward one another and rigidly secured at the corners, as for example by welding, the opposite side members of the frame assembly being designated as 64 while the top and bottom frame members are designated respectively as 65 and 66. The width of the channel shaped frame members as measured between the channel flanges is slightly larger than the front-to-back width of the blades assembly 62 so that the latter fits fairly closely between the flanges of the frame side members 64, and the length of the blade assembly 62 as measured from side to side of the fire damper unit is just slightly less than the distance between the inside surfaces of the frame side members 64 which form the side walls of the frame assembly 61.

The blade assembly 62 is compactly reversely folded to form a blade stack of the type previously seen in the showings of FIGURES l and 2, and this assembly is pivotally secured within the frame assembly 61 at the upper end thereof by means of pivot shaft 67 carried by the upper blade of the blade assembly 62, the pivot shaft 67 being projected through the frame side members 64 so that the blade assembly may open out by unfolding downward as a curtain in the manner best seen in the showing of FIGURE 8. The blade assembly 62 is secured at the upper end of the frame assembly 61 by means of the cinch cable 68 and fire link 69, the cinch cable 68 passing throughthe side flanges of the frame top member 65 just above the blade assembly itself. The blade assembly 62 is gravity actuated when the fire link 69 opens due to the occurrence of the predetermined high temperature condition, drop assistance being provided by the bar weight 70 secured to the lowermost blade of the blade assembly 62, as for example is seen in the showings of FIGURES 7 and 8.

The mounting assembly 63 consists of a flat rectangular bottom plate 71, a pair of opposite flat side plates 72 and a top cap or head 73. The top cap 73 is of inverted U-shape or channel shape, having a channel base wall 74 seated flat-wise upon the upper surface of the frame top member 65, and having side walls 75 extending downward in 'front of and behind the frame assembly 61 for a distance substantially equal to the vertical depth of the compacted blade assembly 62, the side walls 75 being turned horizontally outward away from the frame assembly 61 at both the front and the back thereof to form the flanges 76. The upper ends of theside plates 72 are cut away at the upper corners to conform to the cross sectional shape of the top cap 73, all of the mounting assembly members being fixedly rigidly secured to one another at their meeting edges and being secured,

as by spot welding, to the flat planar surfaces of the frame assembly against which they are flatwise disposed. The bottom plate 71, side plates 72 andflanges'76 of the top cap 73 are provided with a plurality of mounting holes 77 spaced apart peripherally thereabout so that the damper unit may be fixedly secured to the duct system within which it is positioned, as for example to the ends of the ducts 78 shown in FIGURE 7 in fragmentary form and in phantom in FIGURES 6 and 8.

The fire damper assembly of FIGURES 6, 7 and 8 is observed to be one in which the height of the frame assembly 61 is greater than the height of the duct system by an amount sufficient to allow the blade assembly 62 to be positioned in its folded compacted form upward out of the duct air stream and to thereby avoid presenting an apparent restriction in the duct cross-sectional area, the mounting assembly 63 elfectively preventing any appreciable air leakage at the joint of the duct system.

The damper structure illustrated in FIGURE 9 differs from that shown in FIGURES 6, 7 and 8 only in that the mounting assembly 'thereof is formed from flat rectangular top and bottom plates 79 and side plates 80, and is mountable completely within the associated duct work Without any protruding upper part corresponding to the region of the top cap 73. Of course, the blade assembly 62' necessarily extends downward partly into the air flow cross section of the duct in this particular form of structure. The frame assembly and blade asembly of the structure shown in 'FIGURE 9 correspond of course to those of FIGURES 6, 7 and 8, and are therefore designated by primed reference characters for corresponding parts. The frame assembly and blade assembly of the fire damper constructions shown in FIGURES 6 through 9 may therefore be considered as a modular structure of desired height and width to which may b secured a particular desired type of mounting assembly as may be determined by the specific installation.

While the showings of FIGURES 6 through 9 are d'irec ted toward fire damper modular structures intended for positioning in a vertical plane within a duct structune and are thereby enabled to utilize the force of gravity to unfold the blade assembly, the gravity actuation of the blade assembly is not possible when the damper unit must be positioned so that the blade assembly is in a horizontal plane when opened out to close the crosssection of a vertically running duct. The blade assembly of a horizon-tally disposed damper structure requires a positive actuation device, one form of such a structure being illustrated in the showings 0 f FIGURES 10 through 12 to which attention should be now directed.

The frame assembly in FIGURES 10, 1 1 and 12 is the same as that of FIGURES 6 through 9 and is therefore designated 61a. 'Ilhe blade assembly being similar to that also previously described is designated 62a, and its associated cinch cable and fire link and pivot shaft are respectively designated as 68a, 69a and 67a. The blade assembly 62a dilfers from the previously described assembly of FIGURES 6 through 9 in that the bar weight 70 normally secured to the bottom blade of the assembly has been eliminated. In its stead -there have been secured to the blade next to the fire link, designated as 1, a pair of hooks 82 secured as by means of the nuts P3 to the blade 81 proximate the opposite ends of the atter and between the side walls of the channel shaped 'rame side members 64a. Secured to each one of the IOOkS 82 is one end of a constant tension spiral spring 14 which extends between the side walls of the frames .ide members 64a to a take-up spool '85 mounted upon in L-shaped bracket 86 secured as by rivets 87 to one aide wall 88 of the frame member 66a. The take-up pool 85 is so positioned by means of the bracket 86 :hat the free end of the blade 81 may readily move into ihe frame member 66 under the spring and take-up spool 35 in the manner most clearly seen in the showing of FIGURE 12.

The constant tension spiral extension spring '84 is made of flat strip material and may be of the type marketed by Hunter Spring Company of Lansdale, Pennsylvania, under the trade name Negator, these springs exerting the same pulling force on the blade assembly when the latter is in the position shown in FIGURE 12 as when the blade assembly is in the compacted form shown in FIGURES 10 and 11. The fire damper module intended for horizontal plane disposition and illustrated in the showings of FIGURES 10 through 12 may be provided with any convenient type of mounting assembly for installing the damper structure in an air flow system.

Those aspects of the fire damper structures illustrated in FIGURES 1 through 12 which have been thus far described in detail have related to the framing, mounting and actuating portions of the composite damper, and have presupposed

blade assemblies

31, 62, 62' and 62a as being operative. 'Dhe operability of the blade assemblies is of course critically dependent upon the interfitted hinging relationship of the blades to one another, and

a better understanding of this action is best obtained from a consideration of FIGURES 13 through 19. FIG- URE 13 illustrates the somewhat unconventional configuration of the blade edges which form the hinging structures, while FIGURES 14 through 19 illustrate the relative positions of the blades hinging edges as a pair of blades are rotated relatively to one another through substantially 180, FIGURE 14 corresponding to the compacted or folded condition of a blade assembly, while FIGURE 19 corresponds to the opened out or fiat curtain condition of the blade assembly.

Referring first to FIGURE 13, it is observed that the blade is formed from a planar web of thickness 2 which is designated by the reference character W, and which has formed at its opposite ends the hinge edges 89 and 90, the edge 89 *forming the inside portion of the hinge Structure and the edge 90 'forming the outside portion of the hinge structure, all as shown in the views of FIG- URES 14 through 19. The inside hinge section 89 and the outside hinge section 90 are both subdivided into curved and straight regions each of which is designated by alphabetic reference characters, the curved regions A, -B and C of section -89 and the curved regions AA, 'BB and CC of section 90 all being in the form of circular arcs. The circular arc sections A and C are generated about the center point X1 while the circular arc B is generated about the point X2 in the inside hinge section 89. Similarly, the arcs AA and CC are generated about the point Y1 as a center while the circular arc BB is generated about the point Y2.

The points X1 and X2 lie on a line which is parallel to the sides of the straight section S, with these points being separated by the length of the section S which joins the circular arc section A to the circular arc section B. The points Y1 and Y2 of the outside hinge section 90 are similarly located with respect to the curved sections AA, BB and intervening straight section SS. The section I in the outside hinge edge 90 is a short transition or joining section which permits the smooth joinder of the ends of curved sections BB and CC, the transition section being generally so short as to be visually unobservable. The binge terminating sections D and DD are substantially straight with the opening defined between the curved section A and straight section D being somewhat greater than the thickness 1? in order to allow the entrance therebe-tween of the end of curved section AA, as is most clearly seen in FIGURES 15 and 16. The opening defined between the end of curved section AA and straight section DD of the outside hinge edge is somewhat greater than twice the thickness t of the blade material but will be more generally determined by the length of section S, as also ibest seen in FIGURES 15 and 16, and which will become clear as the description proceeds.

It should be noted that the center of the hinging rotation is identified as X1Y1 in the rotational views of FIGURES 14 to 19 because the points X1 and Y1 of the inside and

outside hinge sections

89 and 90 respectively become coincident when the hinge sections are intenfitted. It should also be observed that the center of rotation points X 1 and Y1 are considerably laterally ofiset from the centroids of the respective inside and outside hinging

sections

89 and 90. The need for such a centroidal offset will become clear as the description progresses, although prior to the instant invention this fact had never been recognized and attempts were consequently made to fashion hinging structures from circular or spiral configurations in which the centroid was placed at the axis of rotation. These latter types of configurations will function so long as the hinging range is restricted to approximately 90, but any attempt to utilize such structures for rotation approaching 180 results in .a condition wherein the interfitted blades either fall apart on the one hand or become bindingly engaged on the other hand.

Referring now first to FIGURE 14 which illustrates the folded condition of a blade assembly, and consequently one of the extreme positions of the adjacent blades, assume that only the circular curved sections A and AA of hinging sections 8-9 and 90 exist, and that the remainder of the inside and outside hinge configuration have not as yet been generated. With the foregoing in mind refer now to FIGURE 19 which illustrates the other extreme position of the adjacent blades and which shows that circular curved section A has been rotated about center X*1Y1 in -a clockwise sense through approximately In order that the web sections W1 and W2 achieve a parallel planar relationship, it is necessary that the curved section A be joined to the web section W2 by a structure which does not mechanically intersect the curved section AA. This is best achieved by extending one end of the curved section A in a straight line past the tip of the curved section AA, as illustrated by the straight section S, and then to follow around the outside contour of the section AA by adding the curved sections B and C. This procedure automatically establishes sufiicient clearance distance between the end of curved section A and sections D or C to permit the rotational movement of section AA, this opening distance being as before indicated somewhat in excess of the thickness t of the blade stock.

Now, with sections A, S, B and C of the inside hinge section 89 established in the manner just described, this just generated structure may be rotated counter-clockwise to move it back into the position shown in FIGURE 14. Sections SS, BB and CC may now be added to the end of section AA of the outside hinge portion 90 by following around the con-tour of the previously generated inside hinge section 89. Sufficient clearance is of course maintained between the inside and outside hinging

sections

89 and 90 as is shown in the figures. The terminating sections D and DD connect the flat planar web portions W to the now generated hinge sections. The angle between the webs W1 and W2 in FIGURE 14 follows from the nature of the compacted reversely folded blades, as for example is most clearly seen in the showing of FIGURE 2 illustrating such a reversely folded compacted blade assembly. Obviously, for a given gauge of metal from which the blades are formed, the angle between the web portions of the adjacent blades decreases as the length of the web W increases between the inside and outside hinging

portions

89 and 90 of a given blade since the size of the hinging structures is independent of the web length and depends only upon the thickess t of the blade material and the radius of curvature of the curved portion A of inside hinge section 89.

The 180 extent of curved section A derives from the fact that approximately 180 of rotation between adjacent blades is desired. The angular extent of section AA of outside hinge section 90 need not be 180 to maintain contact with section A, and in fact cannot be such in any physically realizable structure. The resection or cut back on the angular extent of curved section AA is readily determinable from FIGURE 19 after the rotation of curved section A and the addition of straight extension S, the inside bounding edge of the straight section S determining the maximum extent of curved section AA which will prevent intersection thereof with the portion S. Consequently, the end of curved section AA cannot be rotated beyond the point indicated in FIGURE 19 without coming into positive abutment with the straight section S, and hence, a positive stop action between adjacent blades results when the desired degree of rotation has occurred. It should be appreciated, however, that curved section AA cannot be resecte'd back arbitrarily, but such cut back is limited to that which will still prevent fall apart or disengagement of the hinging sections in the rotational position shown in FIGURE 17 for example.

The resultant previously described hinging structure exhibits a compound type of interfit which may be separated into two specifically different forms. One form of such interfit is clearly observed in FIGURES 14 and 15 as being of the type generally known as head and socket. FIGURES 17, 18 and 19 illustrate what might best be characterized as a laminar entry type of motion in which the curved end section AA slides into the inside of the hinge section 89. FIGURE 16 illustrates a transition region in which the relationship between the hinging

parts

89 and 90 is partly that of the head and socket arrangement and is also partly that of the laminar entry structure. The angular relationships between the webs W1 and W2 in FIGURES 15 through 18 are respectively 90, 120, 163 and 170, the 163 showing of FIGURE 17 illustrating the point of complete departure from any semblance of a head and socket arrangement between the inside and

outside hinge parts

89 and 90.

Having now described my invention in connection with particular embodiments thereof, it will be clear that modifications and variations thereof may now occur from time to time to those persons normally skilled in the art without departing from the essential scope or spirit of my invention, and accordingly it is intended to claim the same broadly as well as specifically as is indicated by the appended claims.

What is claimed to be new and useful is:

1. A fire damper assembly comprising in combination,

(a) a rigid rectangular frame including top, bottom and opposite side members which define a main frame plane common to all of said frame forming members and transverse to the air flow path through said frame,

(b) a blade assembly including a plurality of individual damper blades adjacent ones of which are pivotally interconnected by interfitted hinging elements carried by parallel longitudinally extending blade edges, the axis of pivotal rotation of said interfitted hinging elements being offset from the centroids of each of said hinging elements to effect substantially 180 relative rotation between adjacent blades,

(ic) pivot means carried by one blade of said blade assembly and supported by said frame mounting said blade assembly in said rectangular frame,

(d) means securing the blades of said assembly reversely folded one against another to form a compacted assembly characterized by the disposition of the hinge assemblies in planes substantially parallel to the said main frame plane, said securing means including a binding element and a temperature responsive fusible link disposed about said blade assembly, and

(e) means elfective to cause said blade assembly to unfold and close the air flow path through said frame by effecting relative rotation between adjacent blades of saidassembly of substantially when said securing means is rendered inoperative.

2. A fire damper assembly as set forth in claim 1 wherein,

(a) said blade assembly pivot means is carried by the free hinging element of one end blade of the said blade assembly, and which pivot means is supported by said frame opposite side members at points immediately adjacent to said frame top member, and

(b) said blade assembly securing means binding element comprises a flexible element.

3. A fire damper assembly comprising in combination,

(b) a blade assembly including a plurality of individual damper blades adjacent ones of which are pivotally interconnected by interfitted hinging elements carried by parallel longitudinally extending blade edges to effect substantially 180 relative rotation between adjacent blades,

(c) pivot means carried by one blade of said blade assembly and supported by said frame mounting said blade assembly in said rectangular frame,

(d) means securing the blades of said assembly reversely (folded one against another to form a compacted assembly characterized by the disposition of the hinge assemblies in planes substantially parallel to the said main frame plane, said securing .means including a binding element and a temperature responsive fusible link disposed about said blade assembly, and

(e) means including spring means carried by said frame Within the plane thereof and engaged with at least one of the blades of said blade assembly effective to cause said blade assembly to unfold and close the air flow path through said frame by effecting relative rotation between adjacent blades of said assembly of substantially 180 whensaid securing means is rendered inoperative.

4. A fire damper assembly comprising in combination,

(a) a rigid rectangular frame having top, bottom and side members defining a frame main plane transverse to the air flow path through said frame, said frame having a pair of spaced apart parallel bladeguiding elements extending longitudinally of each of said side members with the blade-guiding elements associated with one side member being parallel to and facing the correspondingly positioned bladeguiding elements associated with the other side member to thereby conjointly define a pair of facing blade-guidin g trackways,

(b) a blade assembly including a plurality of individual damper blades, each of said damper blades being characterized by a central web and a pair of parallel longitudinally extending different hinge elements disposed respectively at opposite edges of said web, said hinge elements being of dilferent cross-sectional shape and so formed to interfit withthe one another to form hinge assemblies that one type of hinge element .is interfitted with the other type of hinge element on the adjacent one of said plurality of blades to form a composite blade assembly in which adjacent blades are relatively rotatable through an angle of substantially 180, whereby said blade assembly may be opened out into flat curtain form and may be compacted into a minimum volume by reversely folding adjacent blades of said assembly against one another, said blade assembly being of a length less than the distance between the said frame side members to prevent end binding, and being of a width when compacted as aforesaid which is not greater than the distance between the said parallel blade-guiding elements associated with each frame side member,

(c) means mounting said blade assembly in said rectangular frame between said side members, said blade assembly mounting means including pivot means carried by the free hinge element of one end blade of said blade assembly andsupported by said frame immediately adjacent to said frame top member, whereby said blade assembly when compacted is disposed immediately adjacent to said frame top member and between said frame side members,

(d) means releasably securing the blade assembly in its aforesaid compacted form with the hinge assemblies disposed in planes substantially parallel to the frame main plane and between the said blade-guiding elements, and

(e) spring means carried by said frame within the plane thereof and engaged with at 'least one of the blades of said blade assembly effective to open out said blade assembly into its flat form and close the air flow path through said frame by effecting relative rotation between adjacent blades of said blade assembly of substantially 180 when said releasable securing means is released.

5. A fire damper assembly comprising in combination,

(a) a rigid rectangular frame having top, bottom and side members defining a frame main plane transverse to the air flow path through said frame, said frame having a pair of spaced apart parallel blade-guiding elements extending longitudinally of each of said side members with the blade-guiding elements associated with one side member being parallel to and facing the correspondingly positioned blade-guiding elements associated With the other side member to thereby conjointly define a pair of facing bladeguiding trackways, each of said pairs of blade-guiding elements being vanes pivotally mounted to said frame for swinging movement toward one another about axes parallel to their longitudinal extent to thereby reduce the width of the said trackways,

(b) a blade assembly including a plurality of individual damper blades, each of said damper blades being characterized by a central web and a pair of parallel longitudinally extending different hinge elements disposed respectively at opposite edges of said web, said hinge elements being of different crosssectional shape and so formed to interfit with one another to form hinge assemblies that one type of hinge element is interfitted with the other type of hinge element on the adjacent one of said plurality of blades to form a composite blade assembly in which adjacent blades are relatively rotatable through an angle of substantially 180, whereby said blade assembly may be opened out into flat curtain form and may be compacted into a minimum volume by reversely folding adjacent blades of said assembly against one another, said blade assembly being of a length less than the distance between the said frame side members to prevent end binding, and being of a width when compacted as aforesaid which is not greater than the distance between the said parallel blade-guiding elements associated with each frame side member,

(c) means mounting said blade assembly in said rectangular frame between said side members,

(d) means releasably securing the blade "assembly in its aforesaid compacted form with the hinge assemblies disposed in planes substantially parallel to the frame main plane and between the said blade-guiding elements, and a (e) spring means carried by said frame and drivingly engaged with each of said pairs of pivoted vane blade-guiding elements effective to swingithe latter toward one another as aforesaid to reduce the width of said blade guiding trackways and aid in opening out said blade assembly into flat curtain form to close the air flow path through said frame by effecting relative rotation between adjacent blades of said blade assembly of substantially when said releasable securing means is released.

6. The fire damper assembly as defined in claim 5 further including auxiliary spring means disposed between at least two adjacent blades of said blade assembly effective to provide an initial blade assembly unfolding drive when said releasable securing means is released.

7. For use in a folding shutter, a blade assembly comprising a plurality of individual one piece blades each of which is formed from substantially constant thickness sheet material, each blade including a central web and a pair of parallel extending different hinge elements formed respectively at opposite edges of said web and extending longitudinally continuously for substantially the full Web length, one form of hinge element being interfittable within the other form of hinge element on an adjacent blade by sliding the former endwise into the latter, each of said hinge elements being of asymmetric shape in crosssection and when interfitted with the other form of hinge element being relatively rotatable through substantially 180 about an axis non-coincident with the centroidal axis of either of said hinge elements, whereby said blade assembly may be opened out into flat curtain form and may be compacted into a minimum volume by reversely folding adjacent blades of said assembly against one another, at least one hinge element of each of alternate blades physically engaging one another when said blade assembly is compacted.

8. For use in a folding shutter, a blade assembly comprising a plurality of individual one piece blades each of which includes a central web and a pair of parallel extending different hinge elements formed respectively at opposite edges of said web and extending longitudinally continuously for substantially the full web-length, one form of hinge element being interfittable within the other form of hinge element on an adjacent blade by sliding the former endwise intotthe latter, each of said hinge elements being of asymmetric shape in cross-section and when interfitted with the other form of hinge element being relatively rotatable through substantially 180 about an axis non-coincident with the centroidal axis of either of said hinge elements, whereby said blade assembly may be opened out into flat curtain form and may be compacted into a minimum volume by reversely folding adjacent blades of said assembly against one another, the crosssectional shape of each of said hinge elements comprising a free end curved section of circular curvature joined to a straight section which is in turn joined to a second curve section, the centers of curvature of said first and second curved sections being located within the confines of the hinge element and facing the same surface of the material forming the blade.

9. For use in a folding shutter, a blade assembly comprising :a plurality of individual one piece blades each of which is formed from substantially constant thickness sheet material, each blade including a central web and a pair of parallel extending different hinge elements formed respectively at opposite edges of said web and extending longitudinally continuously for substantially the full web-length, one form of hinge element being interfittable within the other form of hinge element on an adjacent blade by sliding the former endwise into the latter, each of said hinge elements being of asymmetric shape in crosssection and when interfitted with the other form of hinge element being relatively rotatable through substantially 180 about an axis non-coincident with the centnoidal axis of either of said hinge elements, whereby said blade assembly may be opened out into flat curtain form and may be compacted into a minimum volume by reversely folding adjacent blades of said assembly against one another, the cross-sectional shape of each of said hinge elements comprising a free end curved section of circular curvature joined to a straight section which is in turn joined to a second curved section, the said straight sections of both said hinge elements being substantially the same in length, the centers of curvature of said first and second curved sections being located within the confines of the hinge element and facing the same surface of the sheet material forming the blade.

10. For use in a folding shutter, a blade assembly comprising a plurality of individual one piece blades each of which includes a central Web and a pair of parallel extending different hinge elements formed respectively at opposite edges of said Web and extending longitudinally continuously for substantially the full web-length, one form of hinge element being interfittable within the other form of hinge element on an adjacent blade by sliding the former end-wise into the latter, each of said hinge elements being of asymmetric shape in cross-section and when interfitted with the other form of binge element being relatively rotatable through substantially 180 about an axis non-coincident with the centroidal axis of either of said hinge elements, whereby said blade assembly may be opened out into fiat curtain form and may be compacted into a minimum volume by reversely folding adjacent blades of said assembly against one another, the crosssectional shape of each of said hinge elements compris ing a free end curved section of circular curvature joined to a straight section which is in turn joined to a second curved section, the said straight sections of both said hinge elements being substantially the same in length and the said curved sections within each hinge element being of substantially the same radius of curvature.

11. For use in a folding shutter, a blade assembly comprising a plurality of individual one piece blades each of which includes a central web and a pair of parallel extending different hinge elements formed respectively at opposite edges of said web and extending longitudinally continuously for substantially the full web-length, one form of hinge element being interfittable within the other form of hinge element on an adjacent blade by sliding the former endwise into the latter, each of said hinge elements being of asymmetric shape in cross-section and when interfitted with the other form of hinge element being relatively rotatable through substantially 180 about an axis non-coincident with the centroidal axis of either of said hinge elements, whereby said blade assembly may be opened out into flat curtain form and may be compacted into a minimum volume by reversely folding adjacent blades of said assembly against one another, the cross-sectional shape of each of said hinge elements comprising a free end curved section of circular curvature joined to a straight section which is in turn joined to a second curved section, said hinge elements being interfitted so that the centers of curvature of their free end curved sections are coincident with each other and with the axis of hinging rotation.

12. For use in a folding shutter, a blade assembly comprising a plurality of individual one piece blades each of which includes a central web and a pair of parallel extending different hinge elements formed respectively at opposite edges of said web and extending longitudinally continuously for substantially the full web length, one form of hinge element being interfittable within the other form of hinge element on an adjacent blade by sliding the former endwise into the latter, each of said hinge elements being of asymmetric shape in cross-section and when interfitted with the other form of hinge element being relatively rotatable through substantially about an axis non-coincident with the centroidal axis of either of said hinge elements, whereby said blade assembly may be opened out into flat curtain form and may be compacted into a minimum volume by reversely folding adjacent blades of said assembly against one another, the cross-sectional shape of each of said hinge elements comprising a free end curved section of circular curvature joined to a first straight section followed by second and third curved sections and a terminating straight section which latter joins the hinge element to the blade central web.

13. For use in a folding shutter, a blade assembly comprising a plurality of individual one piece blades each of which includes a central web and a pair of parallel extending different hinge elements formed respectively at opposite edges of said web and extending longitudinally continuously for substantially the full web length, one form of hinge element being interfittable within the other form of hinge element on an adjacent blade by sliding the former endwise into the latter, each of said hinge elements being of asymmetric shape in cross-section and when interfitted with the other form of hinge element being relatively rotatable through substantially 180 about an axis non-coincident with the centroidal axis of either of said hinge elements, whereby said blade assembly may be opened out into flat curtain form and may be compacted into a minimum volume by reversely folding adjacent blades of said assembly against one another, the cross-sectional shape of each of said hinge elements comprising a free end curved section of circular curvature joined to a first straight section followed by a second and third curved sections and a terminating straight section which latter joins the hinge element to the blade central web, the said first straight sections of both said hinge elements being substantially the same in length, and the free end and second curved sections within each hinge element being of substantially the same radius of curvature while the third curved section within each hinge element is of substantially larger radius of curvature than the other curved sections of that hinge element.

14. For use in a folding shutter, a blade assembly comprising a plurality of individual one piece blades each of which includes a central web and a pair of parallel extending different hinge elements formed respectively at opposite edges of said' web and extending longitudinally continuously for substantially the full web length, one form of hinge element being interfittable within the other form of hinge element on an adjacent blade by sliding the former endwise into the latter, each of said hinge elements being of asymmetric shape in cross-section and when interfitted with the other form of hinge element being relatively rotatable through substantially 180 about an axis non-coincident With the centroidal axis of either of said hinge elements, whereby said blade assembly may be opened out into flat curtain form and may be compacted into a minimum volume by reversely folding adjacent blades of said assembly against one another, the cross-sectional shape of each of said hinge elements comprising a free end curved section of circular curvature joined to a first straight section followed by second and third curved sections and a terminating straight section which latter joins the hinge element to the blade central web, said hinge elements being interfitted so that the centers of curvature of their free end curved sections are coincident with each other and with the axis of hinging rotation.

-15. For use in a folding shutter, a blade assembly comprising a plurality of individual one piece blades each of which includes a central web and a pair of parallel extending different hinge elements formed respectively at opposite edges of said web and extending longitudinally continuously for substantially the full web-length, one form of hinge element being interfittable within the other form of binge element on an adjacent blade by sliding the former endwise into the latter, each of said hinge elements being of asy-mmetric shape in cross-section and when interfitted with the other form of hinge element being relatively rotatable through substantially 180 about an axis non-coincident with the centroidal axis of either of said hinge elements, w-hereby said blade assembly may be opened out into flat curtain form and may be compacted into a minimum volume by reversely folding adjacent blades of said assembly against one another, the crosssectional shape of each of said hinge elements comprising a free end curved sect-ion of circular curvature joined to a straight section which is in turn joined to a second curved section, said hinge elements being interfitted so that the centers of curvature of their free end curved sections are coincident with each other and with the axis of hinging rotation, the arcuate extent of the free end curved sections of both hinge elements and the length of the straight section of the inner hinge element being such that the free end of the free end curved section of the outer hinge element abuts the side of the inner hinge element straight section at the desired limit of opened out blade rotation to thereby provide a positive stop against further relative rotation between adjacent blades.

16. For use in a folding shutter, a blade assembly comprising a plurality of individual one piece blades each of which includes a central web and a pair of parallel extending different hinge elements formed respectively at opposite edges of said web and extending longitudinally continuously for substantially the full web length, one form of binge element being interfittable within the other form of hinge element on an adjacent blade by sliding the former endwise into the latter, each of said hinge elements being of asymmetric shape in cross-section and when interfitted with the other form of hinge element being relatively rotatable through substantially 180 about an axis non-coincident with the centroidal axis of either of said hinge elements, whereby said blade assembly may be opened out into flat curtain form and may be compacted into a minimum volume by reversely folding adjacent blades of said assembly against one another, the crosssectional shape of each of said hinge elements comprising a free end curved section of circular curvature joined to a first straight section followed by second and third curved sections and a terminating straight section which latter joins the hinge element to the blade central web, said hinge elements being inter-fitted so that the centers of curvature of their free end curved sections are coincident with each other and with the axis of hinging rotation, the arcuate extent of the free end curved sections of both hinge elements and the length of the first straight section of the inner hinge element being such that the free end of the free end curved section of the outer hinge element abuts the side of the inner hinge element first straight section at the de-' sired limit of opened out blade rotation to thereby provide a positive stop against further relative rotation between adjacent blades.

17. A blade assembly for a folding shutter comprising a plurality of one piece blades each of which is formed from substantially constant thickness sheet material, each blade including a central web and a pair of parallel extending hinge elements formed respectively at opposite edges of said web and extending longitudinally continuously for substantially the full web length, one hinge element on one blade being interfittable within a hinge element on an adjacent blade by sliding the former endwise into the latter to form a hinged blade pair, each of said hinged blades of said pair when interfitted with the other being relatively rotatable through a sufiicient angle so that said blade assembly may be opened out into flat curtain form and may also be compacted into a minimum volume by reversely folding blades of said assembly against one another, at lea-st one hinge element of each of alternate blades physically engaging one another when said blade assembly is compacted.

References Cited by the Examiner UNITED STATES PATENTS 790,632 5/1905 Hall -235 X 848,853 4/1907 Reed 160-35 X 1,205,707 11/1916 Cahill 160-235 X 1,939,728 12/1933 Spaunburg 16-178 X 2,586,561 2/1952 Poggi 160-235 X 2,804,641 9/1957 Zavada 16-128 X 2,992,450 7/ 19 61 Pittenger 160-192 X HARRISON R. MOSELEY, Primary Examiner. P. M. CAUN, Assistant Examiner.

Claims

17. A BLADE ASSEMBLY FOR A FOLDING SHUTTER COMPRISING A PLURALITY OF ONE PIECE BLADES EACH OF WHICH IS FORMED FROM SUBSTANTIALLY CONSTANT THICKNESS SHEET MATERIAL, EACH BLADE INCLUDING A CENTRAL WEB AND A PAIR OF PARALLEL EXTENDING HINGE ELEMENT FORMED RESPECTIVELY AT OPPOSITE EDGES OF SAID WEB AND EXTENDING LONGITUDINALLY CONTINUOUSLY FOR SUBSTANTIALLY THE FULL WEB LENGTH, ONE HINGE ELEMENT ON ONE BLADE BEING INTERFITTABLE WITHIN A HINGE ELEMENT ON AN ADJACENT BLADE BY SLIDING THE FORMER ENDWISE INTO THE LATTER TO FORM A HINGED BLADE PAIR, EACH OF SAID HINGED BLADES OF SAID PAIR WHEN INTERFITTED WITH THE OTHER BEING