Abstract:
A “quick change” restrictor assembly that allows quick rebalancing of flow-pressures within a duct system. The invention comprises a removable restrictor plate, a branch circuit for receiving the plate, and a means for retaining the restrictor plate to the branch circuit. The circuit includes a feature that allows for removal and installation of the restrictor plate without removing the branch circuit, inlet or outlet ducting. The quick change restrictor will not require bonding and can be installed easily from outside the duct without any disassembly. The restrictor may also have various clips or tabs to reinforce the slot the restrictor plate is inserted into. The restrictor may also have a smart part number and color code that is visible from outside the duct allowing easy removal, identification and inspection.

Description:
FIELD OF THE INVENTION 
       [0001]    This application is related to controlling the airflow through lightweight aircraft ducting and more particularly to an adapter for establishing a branch circuit in an existing installed duct and diverting air from there in a controllable manner. 
       BACKGROUND OF THE INVENTION 
       [0002]    Installed air ducts are typically assembled from tube sections that are coupled with a variety of connectors, tees and vents. Modification of existing systems requires severing the ducting and installing a new connector such as a tee to divert flow in a new direction. Additional vents or control valves can be installed in the branch circuit to regulate the flow. The connectors are expensive and add weight to the system. In addition, installation of a conventional connector permanently alters the ductwork and even if the branch circuit were removed, a replacement coupling would have to be reinstalled. Alterations of this sort sever the continuity of the duct and add potential leaks to the system. 
         [0003]    When a branch duct is added to a ducting system, a method is required to control the airflow through that branch. Commonly, this is done by inserting a perforated metal or plastic “restrictor plate” into the duct joint. Sometimes, restrictor plates are installed on branch ducts such that the airflow through the duct tends to pull the aperture away from the branch. An adhesive or bonding agent is generally used to ensure that restrictor plates do not become detached or misaligned within the duct. Adhered restrictor plates are also less susceptible to vibration and will retain more strength following damage due to corrosion. Further, adhered restrictor plates cannot be misplaced when ducting is disassembled for maintenance. 
         [0004]    Unfortunately, using bonding agents can present problems. Bonding agents require time to cure, consequently manufacturing planners typically desire all restrictor plates to be bonded to the ducts at the assembly level to reduce delays in a factory. This practice can be impractical however; if assembly drawings are released before a final determination of the flow balance for an application is available. Furthermore, late customer changes and problems discovered during air flow balance tests can also lead to restrictor plate changes, sometimes moments before delivery. Making these changes on the assembly level would require significant changes to assembly and installation drawings at a considerable cost. 
         [0005]    Accordingly there exists a need to enable late-stage modification and installation of airflow restrictor plates to accommodate engineering processes, preventing accidental changes to restrictor plates during modification to ensure safety and performance, while avoiding the expense and delays of bonding to accommodate manufacturing processes. 
         [0006]    This concept allows a conventional, easy-to-analyze, restrictor that can be quickly inspected and changed without disassembling or severing ducts into pieces. The design attempts to dramatically reduce the time to install restrictor plates, the time to inspect and verify restrictor installations, and the time to change restrictor plate installations after assembly. 
     
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0007]      FIG. 1  is an illustration of one embodiment of the invented quick change restrictor plate device, installed in a 90° branch duct assembly configuration. 
           [0008]      FIG. 2  Is an illustration of a closer view of the device and a more detailed depiction of the interconnecting relationship of the tee and nozzle sections. 
           [0009]      FIG. 3  is a perspective illustrative view of one embodiment of the invented quick change restrictor plate device, with an example of an inserted locking pin ( 56 ). 
           [0010]      FIG. 4  are perspective illustrative views of possible restrictor configurations for a quick change restrictor plate with associated labeling. 
           [0011]      FIG. 5  is a disengaged illustrative view of a two piece sections of the adaptor plate holder. 
           [0012]      FIG. 6  is a 45 degree view of the nozzle section ( 12 ) depicting its lower base member seat ( 25 ). 
           [0013]      FIG. 7  is a 45 degree view of the tee section ( 14 ). 
           [0014]      FIG. 8  is an frontal 45 degree view of the nozzle section ( 12 ). 
           [0015]      FIG. 9  depicts illustrations of a variety of possible branch duct configurations for a desired air flow design. The B/A configuration illustrates an, inline splice with two beads assy. The C/A configuration illustrates a, bond-on duct end assy. The D/A configuration illustrates a 90° branch duct assy. The E/C/A configuration illustrates a 45° branch duct assy. 
           [0016]      FIG. 10  is a flow chart depicting the method of assembling the branch circuit adapter and controlling controlling flow from this circuit. 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    A ducting adapter  10 , for creating a branch circuit is shown in  FIG. 1 . Preferably the adapter  10  comprises a first nozzle section  12  and a second “tee” section  14 . The nozzle section includes an opening  20  having a bead  22  for attachment to a duct system (not shown). The nozzle portion  12  includes a base  26  which can be interconnectedly joined with a mating portion  32  of the tee section  14  to form a locking combination that may also include bonding the combination, see  FIGS. 2 ,  7  &amp;  8 , defining a slot opening  28  therein for receiving restrictor plates  50  such as those shown in  FIG. 4  therein. The tee section  14  may include an upper mating joint  32  for engaging the base  26  of the nozzle to assist with, or in lieu of, bonding. As shown in more detail in  FIG. 2  the base  26  is interconnectedly joined with the upper meeting joint  32  to fixedly join the nozzle  12  to the tee section  14 . Together the joint  32  and the base  26  define an opening  28  for receiving a diverter plate therein. 
         [0018]    The tee section  14  also includes an adapter base or saddle  34  for attachment directly to an air supply duct  18  without severing the duct into pieces. Typically a decision is made to add a branch circuit to an existing duct at a particular point. An opening is cut in the duct and the branch circuit adapter  10  is permanently affixed or sealingly affixed to the duct over the opening so that airflow through the opening is directed through the nozzle  20  of the current adapter. The adapter is mounted to the duct with a saddle  34  which can for instance have a configuration adapted to conform to that of the corresponding duct. For example, the saddle would have a 2 inch radius to conform to a 4 inch duct. This sizing allows the saddle to matingly and sealingly engage the duct to ensure desired airflow. The adapter  10  can be permanently mounted with a fastener material such as epoxy cement. One possible alternative configuration would allow bonding the adaptor base to the end of a duct, to provide an interchangeable air flow control point within an air duct. 
         [0019]    The quick change restrictor plate is a flat piece of rigid material with a full radius at one end. The diameter of the curved end of the restrictor plate is generally slightly larger than the nozzle diameter  20 . Its dimensions are sized to receptively match the width, height, and depth of the slot  28  in the branch circuit. The described flat rigid plates may have one hole or many holes. These plates  50  which can be inserted within the slot opening  28  have a variety of configurations specially designed to control the flow of air through a duct circuit. Ideally an restrictor plate can be sized and ported to provide a manufacturer the flexibility to develop particular hole specifications for a desired application. 
         [0020]    When the restrictor plate  50  is installed in a circuit, a portion of the restrictor plate  50  extends beyond the slot  28  and remains exposed, allowing easy removal, identification and inspection. A particular restrictor plate may be clearly identified by part number, open flow area, a color code, or perhaps RF identification can be imprinted on the exposed edge of the plate. 
         [0021]    As is indicated above, the slot opening  28  shown in  FIG. 3  interchangeably receives restrictor plates  50   a ,  50   b ,  50   c  and  50   d ,  50   e , shown in  FIG. 4 , in a snug fit and locked position within the opening. More particularly for this embodiment, the opening  28  has an arciform (shape of an arc) cross section and a restrictor has a similar exterior configuration adapted to fit snugly within the opening  28 . This snug fit insures that the restrictor plate  50  performs optimally and diverts or regulates air in a desired manner. In addition, a locking pin  56  can be inserted through a hole  52  in the restrictor plate  50  into a corresponding opening  22   a  in the adapter joint  32 . The inserted locking pin  56  ensures that the restrictor plate  50  is not dislodged by vibrations. The locking pin  56  avoids the need for glues and allows the restrictor plate  50  to be interchanged as conditions require by removing the locking pin  56 , replacing the restrictor plate  50  and reinserting the locking pin  56 . The function of the locking pin may also be performed by lockwire, a racheting cable tie, a plastic fastener, or any number of other similar devices which may be engaged through a hole. 
         [0022]    While it is recognized that the present structure can be constructed in a single piece, a more practical embodiment employs a two-piece construction to beneficially form a seat  25 ,  33  for the restrictor plate  50  with the opening  28 . As shown in  FIG. 5 , the tee portion  14  includes an upper joint  32  which is shown to comprise a substantially planar or flat U-shaped surface or seat  33 . The seat  33  is optionally surrounded by a U-shaped bead  35   FIGS. 7 &amp; 8  which matingly engages a U-shaped channel  25  on the nozzle section  12 . A lock pin hole  22   a  is provided on the exterior edge of the seat  33 . 
         [0023]    The nozzle portion  12  includes a lower base member  26  for mating with the upper joint  32  of the tee portion  14 . The base member  26  includes a seat  25  having a substantially planar surface and which, when positioned in opposed relation to the seat  33  of the tee portion  14 , forms a U-shaped channel having upper and lower walls  33  and  25  which are approximately parallel. The distance between the upper and lower walls is approximately 0.06 inches or only slightly more than the thickness of a restrictor plate such that a snug fit between the restrictor plate  50  and the opening  28  is ensured. The upper joint includes a U-shaped channel portion having an interior surface for receiving the bead of the upper joint in a snug fit locked position. The upper seat  25  includes a lock pin hole  22   b  through which a lock pin  56  can be inserted. The restrictor plate  50  also includes lock pin openings  52 . When the nozzle portion  12  is inserted within the base portion  14  the nozzle  20  aligns over the opening in the tee and the lock pin opening  22   a  aligns with the lock pin opening  22   b.    
         [0024]    The two piece adapter  10  provides a further benefit when a decision is made to remove a previously installed branch circuit. The locking pin  56  is removed, the restrictor plate  50  is removed, the nozzle portion  12  maybe slidingly separated from the base portion  14  and a closure plate  50   d  maybe inserted in place of the nozzle portion to block the opening. This allows the branch circuit to be quickly and easily removed and the branch circuit efficiently capped avoids the need for further work on the duct itself. Alternately, when no restriction at all is required in a given branch circuit, a “gap filler” plate  50   e  may be used to close slot  28  without placing a restrictor within. This gap filler plate may also include tabs  60  to properly align the gap filler plate within the slot  28 . 
         [0025]    Enhancements to the two piece adapter  10  may include:
       Reinforcing ribs on flanges  26  and  32  to maintain a tight tolerance on the width of slot  28  to prevent leakage.   Gasketing material printed on or applied to the faces of restrictor plate  50  at the point where it engages in slot  28 .   A stiffening clip attached to, or formed as a part of, restrictor plate  50  such that when the restrictor plate  50  is fully engaged into slot  28 , the stiffening clip pinches flanges  26  and  32  at particular points, or along their entire length, such that leakage is reduced through slot  28 .   A stiffening clip attached to the adapter assembly  10  as a separate part which would cover restrictor plate  50  when it is fully engaged into slot  28 , thereby pinching flanges  26  and  32  at particular points, or along their entire length, such that leakage is reduced through slot  28 . This clip would be retained by locking device  56 , or by direct engagement with the adapter  10  or duct  18 .   A cap or sleeve over slot  28  such that leakage is reduced through slot  28 . This cap or sleeve would be preferentially made of a transparent material so that any part number printed on the exposed edge of restrictor plate  50  would still be visible.       
 
         [0031]    In a method of assembling the branch circuit adapter  10 , a location for the branch circuit is first identified. The existing duct  18  is then penetrated and an opening approximately equal to the cross-sectional area of the air channel through the adapter  10  is provided. The adapter saddle  34  is then sealingly secured over the opening to the duct with an appropriate fasting compound such as epoxy. The upper nozzle portion  12  is then lockingly engaged with the tee portion  14 . Alternatively the upper nozzle portion  12  may be bonded to the tee portion by applying an appropriate fastening compound, such as epoxy, along the periphery of nozzle flange  26  and then inserting the nozzle flange  26  within the matching flange on tee portion  14 . Later, when the duct assembly is installed in the airplane, a restrictor plate  50  is then inserted within the opening  28  defined by the opposed surfaces of the nozzle and tee seats  25  and  33  respectively. A locking device, such as locking pin  56 , is inserted through the lock pin openings  22 A,  52 , and  22 B in the nozzle flange  26 , restrictor plate  50  and tee flange  32  respectively to fixedly positioned the diverter plate  50  within the opening  28 . This allows the restrictor plate  50  to remain in position despite substantial airflow through the branch circuit adapter  10 . 
         [0032]    In a method of controlling airflow through a new branch circuit having a branch circuit adapter  10  secured to a duct  18 , airflow is regulated by inserting a restrictor plate  50  within an installed branch circuit adapter  10  to adjust the flow of air respectively and applying a locking pin  56  through the nozzle, adapter and restrictor plates  12 ,  50  and  14  to ensure the restrictor plate  50  remains in position despite high volumes of airflow.