AIR TERMINAL

Abstract: A bellows assembly (30) is secured to a retainer (40) by extrusions having a mushroom or arrow shaped cross section. Air flowing through the terminal (10) impinges upon an imper­ vious film coving the central portion of the device and is diverted into two flow paths. Initially the flow paths ex­ tend between the film and the cutoff plates (24,25) which coact to form a tight shut off. Downstream of the cutoff plates (24,25), the flow paths are between a porous foam covering the bellows and foam(50) surrounding the cutoff plates (24,25) to provide a sound reducing effect. If necessary or desirable, the back of the retainer (40) may be covered with foam or other suitable sound insulating material.

Description: Background of the Invention The present invention relates to an air terminal means. In a parent application published under number EP-A-0 146 485, which is hereby incorporated by reference, a bellows assembly is described which is made up of a bellows and a retainer which coact to form a pair of uniformly spaced seals running the full length of the bellows. The bellows itself is made up of a sheet of film with two extrusions suitably secured thereto at a uniformly spaced distance to form an integral unit. Accordion pleat members located at the two ends completes the seal. The two extrusions run the length of the film and, in cross-section, are of an arrowhead or mushroom configuration and deform to permit attachment of the film member to the retainer. The bellows or bladder coacts with a cut off plate to form a damper. The air flow was over the full width bellows for its entire length and there was no directional change in flowing over the bellows other than that incidental to the flow regulating valving action due to bellows inflation/deflation. The above described damper provides a uniformity of devices such that it was no longer necessary to calibrate every terminal. This design has a flow volume limitations due to the relatively limited width of the single flow path at the full open position. By locating the bellows transversely to the flow, two controlled flow paths or outlets are formed. This modification requires the air to impinge upon the bellows with the air being diverted into two flow paths. The result is a noisier unit. Placing porous foam on the surface impinged upon by the air flow has a sound reducing effect but the foam provides a leakage path which makes shutting the damper essentially impossible when using duct pressure to inflate the bellows since the same pressure is on both sides of the bellows. Also, the amount of leakage varies with the degree of compression of the foam subsequent to the foam contacting the cutoff plates. In US-A-4 399 739, there is described an air terminal means according to the preamble of claim 1. Specifically, US-A-4 399 739 discloses an air terminal means which comprises an elongated slot which is fluidly connected to a plenum and which defines an outlet with side edges on both sides of the elongated slot to define a seating surface having predetermined width, discharge means for discharging air flowing through the slot into a zone, bellows retainer means located transversely to the slot and intermediate the slot and the discharge means. The bellows assembly disclosed in US-A-4 399 739 comprises an elongated rectangular bellows having a top wall and a bottom wall together defining an inflatable chamber therebetween, fluid connection means connected to the bellows for supplying air to and exhausting air from the inflatable chamber so as to cause the top wall of the bellows to be of a configuration which varies between less or more convex, and porous foam secured to the top wall and overlying most of the top wall, whereby when the inflatable chamber is sufficiently inflated, the top wall and porous foam are moved together into a more convex shape thereby engaging the seating surface in a valving action to prevent flow through the slot, and when the inflatable chamber is insufficiently inflated to hold the porous foam in engagement with the seating surface, air flowing through the slot is divided into two flow paths defined by the porous foam and respective ones of the side edges before discharging through the discharge means. It is an object of this invention to provide an air terminal having increased air flow capacity, essentially complete shut off, an acceptable sound level and a reduced minimum pressure requirement. It is another object of this invention to provide an air terminal in which the bellows does not require calibration. These objects, and others as will become apparent hereinafter, are accomplished by the present invention. To achieve this, the air terminal means of the invention is characterized by the features set forth in the characterizing part of claim 1. Essentially, according to the invention, the outlet has cutoff plates extending laterally from both sides of the elongated slot to define the seating surface, the bellows retainer means having a pair of uniformly spaced first attachment means, the elongated rectangular bellows having a pair of uniformly spaced resiliently deformable second attachment means located along both of the longer edges of the bellows and adapted to coact with first attachment means to secure the longer edges of the bellows to the bellows retainer means. The bellows assembly further comprises an impervious film secured to the porous foam and overlying a portion of the porous foam coextensive with the cutoff plates. The configuration of the top wall of the bellows varies between concave and convex. When the inflatable chamber is sufficiently inflated, the top wall, porous foam and impervious film are moved together into the convex shape with the film engaging the cutoff plates in a valving action to prevent flow through the slot, and when the inflatable chamber is insufficiently inflated to hold the film in engagement with the cutoff plates, air flowing through the slot is divided into two flow paths defined by the film and respective ones of the cutoff plates. The bellows is made in the form of a bag or bladder with two extrusions running the length of the bag to provide a uniformity of response that eliminate the need for calibration pursuant to the teachings of the parent application in the above mentioned EP-A-0 146 485. The bag or bladder is located directly in the path of the air which is diverted to either side which nominally doubles the outlet area as compared to the parent application. The surface of the bag or bladder impinged upon by the air is covered with foam to provide a noise reducing effect. However, the foam is, in turn, covered by an impervious film over the portion of the foam between the two cutoffs. As a result, the air flow does not contact the foam upstream of the cutoffs so that an essentially complete shut off, within 1-5% of nominal flow, is achieved. The foam on the bellows is exposed to the air flow downstream of the cutoffs and additional foam or other porous material outside the edges of the cutoffs so that the flow goes between two porous members downstream of the cutoffs. Advantageous embodiments of the invention are claimed in the subclaims. Basically, in an air terminal made up of a plenum, a bellows assembly and a diffuser, air flows from the plenum to the diffuser under the control of the bellows. In passing from the plenum, the air impinges upon the bellows assembly and is divided such that both flows are deflected nominally 90°. The air impinging upon the bellows assembly hits an impervious film which overlies a porous foam member which is, in turn, secured to the bellows. The impervious film extends between the two cutoffs so as to provide an essentially complete shut off. However, the air passing beyond the cutoffs passes between the exposed foam on the bellows and foam or other porous material outside the edges of the cutoffs to provide sound reduction. The air paths are then directed to the diffuser which discharges the air into the room or zone. Brief Description of the Drawings For a fuller understanding of the present invention, reference should now be made to the following detailed description thereof taken in conjunction with the accompanying drawings wherein: Figure 1 is a sectional view of an air terminal incorporating the present invention; Figure 2 is a sectional view of the bellows and cutoff plates; Figure 3 is an enlarged partial sectional view of the attachment structure of the bellows; and Figure 4 is a pictorial representation of the bellows. Description of the Preferred Embodiment In Figure 1, the numeral 10 generally designates and air terminal. Nozzle plate 14 divides plenum 12 into high and low pressure areas 15 and 16, respectively. High pressure pickup 18 extends through the nozzle plate 14 into high pressure area 15 and provides a high pressure input to a flow control device (not illustrated). Low pressure pickup 19 is located within low pressure area 16 and provides a low pressure signal to the flow control device. In the open position illustrated in Figure 1, the air flows from high pressure area 15 through nozzle plate 14 into low pressure area 16. The air then passes through slot 22 and impinges upon the bellows assembly 30 and is diverted 90° into two flows which pass between the bellows assembly 30 and the cutoff plates 24 and 25. The flow is then directed to the diffuser 90 and discharged into the room or zone. It will be noted that the movable portion of bellows assembly 30 is in a concave configuration in the open position. Referring now to Figure 2, it will be noted that bellows assembly 30 is in a convex configuration and that the terminal 10 is closed so that the only time the bellows assembly is not distorted is in an intermediate position in which the terminal is partly open. As best shown in Figures 3 and 4, bellows assembly 30 is made up of polyurethane bellows 32 which has two identical polyurethane extrusions 33 and 34 heat sealed thereto to form an integral unit. The extrusions 33 and 34 are uniformly spaced over the full length of the bellows 32 and, in cross section, are of an arrowhead or mushroom shape with flexible flared edges or barbs 33 a and b and 34 a and b . Bellows 32 is covered by polyurethane foam member 36 which is adhesively secured to bellows 32 in the center portion by adhesive. Foam member 36 is covered by impervious polyurethane film 38 which is adhesively attached thereto and of a width equal to the distance between the outer edges of cutoff plates 24 and 25. Barbs 33 a and b and 34 a and b of extrusions 33 and 34, respectively, are received in recesses 42 and 43 in retainer 40. Retainer 40 is formed as an aluminum extrusion so that the dimensions, particularly the spacing between recesses 42 and 43, are held to close tolerances and the retainer structure is rigid. Similarly, the spacing of extrusions 33 and 34 is held to close tolerances when sealed to bellows 32. As a result, the profile of bellows 32 with respect to cutoff plates 24 and 25 is uniform over its entire length since the spacing of the fixed points of the bellows is uniform. Retainer 40 defines a generally V-shaped recess 41 and therefore is able to receive the bellows assembly 30 when the terminal 10 is open, as illustrated in Figure 1, and the bellows assembly 30 assumes a concave configurarion with respect to the air flow. Recess 41 also receives bellows fitting 46 which is connected to the bleed thermostat and permits the inflation and deflation of bellows 32 under the control of the bleed thermostat. If necessary or desired, foam or another sound absorbing material 45 may be adhesively or otherwise suitably secured to the back of retainer 40 to reduce the sound level. Foam or another suitable sound absorbing material 50 is adhesively or otherwise suitably secured to cutoff plates 24 and 25. The foam 50 is located at the downstream edges of cutoff plates 24 and 25 so as to form a continuous surface therewith. In assembling the bellows assembly 30, extrusions 33 and 34 are forced into recesses 42 and 43, respectively, by causing the flexing or collapsing of flared edges or barbs 33 a and b and 34 a and b which snap back into shape upon entering recesses 42 and 43, as best shown in Figure 3. In operation, the position of the bellows assembly 30 will be dictated by the inflation of bellows 32 which is controlled by the bleed thermostat. Depending upon the position of the bleed thermostat, the bellows 32 may be at plenum pressure and the terminal closed, at atmospheric pressure and the terminal open or at some intermediate pressure with a corresponding degree of opening. In the closed position illustrated in Figure 2, the bellows assembly 30 is at plenum pressure and is of a convex shape with the film 38 being in direct physical contact with cutoff plates 24 and 25 and extending to the outer edges of cutoff plates 24 and 25. Downstream of the edges of the cutoff plates 24 and 25, foam member 36 either engages or is in close proximity with foam 50. In the fully open position illustrated in Figure 1, the bellows assembly is at atmospheric pressure and of a concave shape. In operation, the bellows assembly 30 can assume the convex, closed position of Figure 2, the concave fully open position of Figure 1 or some intermediate position. The position of the bellows assembly 30 is controlled by a bleed valve (not illustrated) in response to the pressures sensed at high pressure pickup 18 and low pressure pickup 19 together with the zone temperature and setpoint. The bleed valve controls the supplying of pressurized air to bellows 32 and its exhausting to atmosphere. When terminal 10 is opened by moving bellows assembly 30 away from cutoff plates 24 and 25 and foam 50, a flow path is established. Air will then flow from high pressure area 15 through nozzle plate 14 into low pressure area 16 and then into slot 22. Air passing through slot 22 impinges upon film 38 and is diverted into two flows in essentially opposite directions. However, the profile of the bellows assembly 30 will influence the direction of the air flow. The two flows will pass between film 38 and cutoff plates 24 and 25, respectively. At a point corresponding to the downstream edges of cutoff plates 24 and 25 and the corresponding edges of film 38, the flow is between foam member 36 and foam 50 which has a sound reducing effect without interfering with the shutting off of the air flow. Foam 48 has an additional sound reducing effect. Metal members 49 cover the edges of foam 48 to reduce the sound level and for its aerodynamic effects. The two air flows are again diverted and pass through diffuser 90 into the room or zone.

Claims: 1. An air terminal means (10) comprising: an elongated slot means (22) which is fluidly connected to a plenum (12) and which defines an outlet, said elongated slot means (22) defining a seating surface having a predetermined width, discharge means (90) for discharging air flowing through said slot (22) into a zone, bellows retainer means (40) located transversely to said slot (22) and intermediate said slot (22) and said discharge means (90), a bellows assembly (30) comprising: (a) an elongated rectangular bellows (32) having a top wall and a bottom wall together defining an inflatable chamber therebetween, (b) porous foam (36) secured to said top wall and overlying most of said top wall, (c) fluid connection means (46) connected to said bellows (32) for supplying air to and exhausting air from said inflatable chamber so as to cause said top wall of said bellows (32) to be of a variable configuration such that when said inflatable chamber is sufficiently inflated, said top wall and porous foam are moved together into a convex shape thereby engaging said seating surface in a valving action to prevent flow through said slot (22) and when said inflatable chamber is insufficiently inflated to hold engagement with said seating surface, air flowing through said slot (22) is divided into two flow paths before discharging through said discharge means (90), characterized in that said outlet has cutoff plates (24,25) extending laterally from both sides of said elongated slot (22) to define said seating surface, said bellows retainer means (40) having a pair of uniformly spaced first attachment means (33,34), said elongated rectangular bellows (32) having a pair of uniformly spaced resiliently deformable second attachment means (42,43) located along both of the longer edges of said bellows (32) and adapted to coact with said first attachment means (33,34) to secure the longer edges of said bellows (32) to said bellows retainer means (40), said bellows assembly (30) further comprising an impervious film (38) secured to said porous foam (36) and overlying a portion of said porous foam (36) coextensive with said cutoff plates (24,25), said configuration of said top wall of said bellows (32) varying between concave and convex, whereby when said inflatable chamber is sufficiently inflated, said top wall, porous foam and impervious film are moved together into said convex shape with said film (38) engaging said cutoff plates (24,25) in said valving action and when said inflatable chamber is insufficiently inflated to hold said film (38) in engagement with said cutoff plates (24,25), said two air flow paths are defined by said film (38) and respective ones of said cutoff plates (24,25). 2. The air terminal means of claim 1, characterized in that said bellows (32), foam (36) and film (38) are made of polyurethane. 3. The air terminal means of claim 1, characterized in that porous means (50) are located on the outer portions of said cutoff plates (24,25) and coact with corresponding portions of said porous foam (36) to define continuations of said two flow paths defined by said film (38) and respective ones of said cutoff plates (24,25). 4. The air terminal means of claim 3, characterized in further including porous means (48) on said bellows retainer means (40).

Inventors: CURRIER, FREDERICK A., HERB, CARL C., INGLIS, STEPHEN C.
Applicants: CARRIER CORPORATION
Application year: 1988
Main classification: F16J3
IPC codes: F16J3, F24F11, F16K7, F24F13, F16K47