Abstract:
A repositionable attenuator for a terminal unit in a heating, ventilation, and air conditioning system is disclosed. The attenuator is positionable between at least a first and a second position. This enables the attenuator to be attached to and shipped with the terminal unit prior to installation of the terminal unit.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Application 60/567,119 filed Apr. 30, 2004, titled REPOSITIONABLE ATTENUATOR, which application is hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND 
     The present invention is directed to an attenuator that can be used in a variable air volume terminal unit, a terminal unit incorporating the attenuator, and clips for fastening the attenuator. 
     Discharge and radiated sound is of concern with variable air volume (VAV) terminal units, such as may be used in heating, ventilation, and air conditioning (HVAC) systems. In a VAV system, one or more central air supply systems are sized to meet the peak cooling (and/or heating) conditions for the building. Several terminal units are located in respective zones or offices throughout the building, each connected via ducts to the central air supply. In such a terminal unit, the volume of air urged through a diffuser over a given length of time is controlled. Some terminal units have a fan or pump driven by a motor to move the air from the central air supply through the diffuser associated with the terminal unit. VAV terminal units permit “personalizing” the temperature of a particular room or group of rooms as desired by the occupants. 
     While there may be several sources of objectionable sound in a HVAC system, at least every component of rotating machinery, e.g., the blower of an air handling unit, generates sound waves which propagate along the duct through the air flowing in the duct. And certain types of VAV terminal units include integral motor-driven fans. Unless attenuated to acceptable levels, the propagated sound waves may be evident to persons in the rooms served by the HVAC system. Conventional attenuators for this sound are external to the terminal unit and are either supplied and installed by the factory or are installed to the terminal unit in the field. 
     SUMMARY 
     An attenuator described in the present disclosure has at least one open side and is internal to the terminal unit and is positionable between at least two positions relative to the casing of the unit. Also described is a terminal unit having an attenuator that is positionable between at least a first position and second position. A kit is also described for fitting a terminal unit with a repositionable attenuator. Also described are clips suitable for use with the repositionable attenuator to allow for repositioning of the attenuator. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the accompanying drawings, which are incorporated in and constitute a part of this specification, embodiments of the invention are illustrated, which, together with a general description of the invention given above, and the detailed description given below, serve to exemplify the principles of this invention, wherein: 
         FIG. 1  is a perspective view illustrating a terminal unit in accordance with the present invention illustrating the attenuator in an “out” position; 
         FIG. 2  is a perspective view illustrating the terminal unit of  FIG. 1  with the attenuator in an “in” position; 
         FIG. 3  is a top view of the terminal unit of  FIG. 1 ; 
         FIG. 4  is a perspective view of the terminal unit of claim  1 ; 
         FIG. 5  is a perspective view of an attenuator in accordance with the present invention; 
         FIG. 6  is a top view of an attenuator clip in accordance with the present invention; and 
         FIGS. 7A through 7F  are schematic drawings of an attenuator clip in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     The present invention is described by exemplary embodiments herein, but is limited only by the claims appended hereto. The invention is capable of many embodiments, depending on the specific circumstances of each desired implementation. Departures from the embodiments described herein may be made by those of ordinary skill in the art without undue experimentation to accommodate a variety of specific implementations without departing from the spirit and scope of the invention. 
       FIG. 1  illustrates a VAV terminal unit  10  having a casing  12 , an attenuator  14 , and attenuator clips  16 .  FIGS. 1 through 4  illustrate the terminal unit  10  without a top portion of the casing  12  to enable illustration of the internal components of the terminal unit  10 . 
     The attenuator  14  is capable of being positioned, such as by sliding, relative to the casing  12  between a first, or “out,” position illustrated in  FIG. 1  and a second, or “in,” position illustrated in  FIG. 2 . In the “out” position, more of the attenuator  14  is outside of the casing  12  of the terminal unit  10  than inside the casing  12 . In the “in” position, more of the attenuator  14  is inside the casing  12  of the terminal unit  10  than outside of the casing  12 . The attenuator  14  may also be completely removed from the casing  12 , for example, to replace the attenuator  14 . 
     Attenuator clips  16  cooperate with appropriate slots  18 ,  20  on the top of the attenuator  14  to retain the attenuator  14  in the “out” or “in” position. The attenuator  14  may also be secured in any position intermediate to the “in” or the “out” positions. Slots  18 ,  20  may be situated at any location on the attenuator  14  to facilitate securing the attenuator  14  in any position between fully removed from the casing  12  and completely inserted within the casing  12 . 
     In one embodiment, the attenuator clips  16  are attached to the casing  12 , such as via holes  30  illustrated in FIGS.  6  and  7 A- 7 C. Fasteners  32  cooperate with the holes  30  and the casing  12  to retain the attenuator clips on the casing  12 . The fasteners  32  may be any conventional fasteners, such as rivets, brads, screws, bolts, studs, pins, etc., without departing from the spirit and scope of the invention. 
     In one embodiment, the attenuator clips  16  are removably fastened to the casing  12 , such as by removable fasteners  32 . In another embodiment, the attenuator clips  16  are secured to the casing  12  without fasteners  32 , such as with an adhesive, glue, resin, or the like. In another embodiment, fasteners  32  are integral with the casing  12 , such as integral protrusions over which the holes  30  snap into place. 
     Attenuator clips  16  may also be provided to cooperate with slots  18 ,  20  located on the bottom or the sides of attenuator  14 , as illustrated in  FIG. 1 . 
       FIGS. 3 and 4  illustrate the attenuator  14  in the “out” position, with the attenuator clips  16  positioned to cooperate with slots  18 . 
       FIG. 5  illustrates the attenuator  14  having four slots  18 ,  20  in a top surface  27  thereof, with corresponding slots  18 ,  20  in a bottom surface  28 . Any number of slots  18 ,  20  may be provided in the attenuator  14  without departing from the spirit and scope of the invention. The attenuator  14  may also be secured in the “in” position and the “out” position in any other manner presently known or later developed. 
     The attenuator  14  illustrated in  FIGS. 1 and 5  has a body  26  with generally a rectangular prismatic shape with a first side  22  and a second side  24  open or at least not completely closed off. The shape of the body  26  of the attenuator  14  can also be described as a hollow box-like structure having the first side  22  and the second side  24  open, or at least not completely closed off. The first side  22  is disposed within the casing  12 . The location of the second side  24  relative to the terminal unit  10  and the first side  22  is dependent on the geometry of the components of the particular terminal unit  10  and may be selected without departing from the spirit or scope of the invention. 
     The relative location of the attenuator  14  within the terminal unit  10  is generally dependent on the geometry and locations of the components within the terminal unit  10 , and may be selected without departing from the spirit and scope of the invention. 
     When the attenuator  14  is in the “out” position, a flow path is enabled from outside the terminal unit  10 , through the second side  24 , into the attenuator  14 , through the first side  22 , and into the interior of the terminal unit  10 . For example, if the terminal unit is placed in an HVAC system, the ambient air outside of the terminal unit  10  may be forced into the terminal unit  10  through the described flow path. The ambient air then mixes with chilled air provided to the interior of the terminal unit  10 , such as through a primary air inlet  40  that is in communication with a chiller system. Then a fan  50  forces the mixed ambient and chilled air through an outlet  60  into a room, conduit, etc. in communication with the outlet  60 . 
     Use of an attenuator  14  that is internal to and part of the terminal unit  10  may enable more accurate predictions for sound mitigation values because the attenuator  14  is a part of the terminal unit  10  and not an after-market addition that may or may not have been tested with the particular terminal unit  10 . The attenuator  14  and the terminal unit  10  may occupy less space than a conventional unit because the attenuator  14  is internal to the terminal unit  10 , possibly resulting in reduced costs for shipping, storage, etc. Also, there may be lower labor costs associated with installation of the attenuator and terminal unit of the present invention. 
     Conventional field-added attenuators can introduce undesirable performance characteristics into operation of a terminal unit, such as fan shift. This can result because the particular after-market, external attenuator may not have been tested with the specific terminal unit, and the operation of the existing terminal unit may have been optimized without the presence of an external attenuator. The terminal unit with repositionable attenuator of the present invention is unlikely to experience fan shift or other such undesirable performance characteristics, because any optimization of the terminal unit operation will be conducted with the attenuator as a part of the original manufacture of the terminal unit. 
     FIGS.  6  and  7 A- 7 F illustrate an attenuator clip  16 . As discussed above, in one embodiment, the attenuator clip  16  is provided with two holes  30  in a flat section  74 . The holes  30  enable the attenuator clip  16  to be fastened to the casing  12 . There may be any number of holes  30  in the attenuator clip  16 . In other embodiments, the attenuator clip  16  does not have holes, and is fastened to the casing in other manners, as discussed above. 
     As best seen in  FIGS. 7C and 7D , in one embodiment the attenuator clip  16  has a V-shaped section, indicated generally by numeral  70 . The bottom  72  of the V-shaped section  70  cooperates with the slots  18 ,  20  to hold the attenuator  14  in place in the “in” or the “out” position. The V-shaped section  70  is connected to the flat section  74 . In the embodiment illustrated in  FIGS. 7A-7D , the V-shaped section  70  is connected to the flat section  74  via a curved section  76 , although direct connection to the flat section  74  is within the spirit and scope of the invention. The curved section  76  is believed to assist with the resiliency of the clip  16  and in the capability of the clip  16  to be biased toward and disengaged from the slot  18 ,  20 . The clip  16  also includes a tab  78  extending from a portion of the V-shaped section  70  closest to the flat section  74  toward the flat section  74 , as illustrated in  FIG. 7D . 
     The attachment of the clip  16  to the casing  12  is such that the V-shaped section  70  is disposed to be capable of cooperation with slot  18 ,  20 . When the slot  18 ,  20  and the V-shaped section  70  are aligned to cooperate, at least a portion of the V-shaped section  70  enters the slot  18 ,  20  to a sufficient depth to secure the attenuator  14 . The tab  78  prevents insertion of the V-shaped section  70  to an undesired depth in the slot  18 ,  20  and enables sufficient structure of the clip  16  to be available to disengage the clip  16  to reposition the attenuator  14 . 
     The bottom  72  of the V-shaped section  70  is offset from the plane of the flat section  74 , for example, “below” the plane of the flat section  74 , as illustrated in  FIG. 7D . This assists in providing a bias of the bottom  72  against the body of the attenuator  14  and the slot  18 ,  20 . Thus, when the slot  18 ,  20  aligns with the bottom  72 , the bottom  72  and V-shaped section  70  will “snap” into place in the slot  18 ,  20 . Force must then be applied to the clip  16  to “lift” or disengage the bottom  72  and the V-shaped section  70  from the slot  18 ,  20 . The clip  16  preferably has sufficient resiliency to enable the disengagement of the V-shaped section  70  from the slot  18 ,  20  without detachment of the clip  16  from the casing  12 . 
     For clips  16  and slots  18 ,  20  associated with the bottom surface  28  of the attenuator, the operation and cooperation are the same, but the directions are different. For example, the bottom  72  is disposed “above” the plane of the flat section  74 . 
     When it is desired to reposition the attenuator  14 , the V-shaped section  70  is disengaged from the slot  18 ,  20 , allowing movement of the attenuator  14  to a different position. When the same or different slot  18 ,  20  is then aligned with the same or different V-shaped section  70 , the V-shaped section  70  engages the slot  18 ,  20  to secure the attenuator  14  at the different position. 
     If there is more than one clip  16  and slot  18 ,  20 , then all clips  16  must be disengaged before the attenuator  14  is moved to the different position. As illustrated in the Figures, for example, there are a plurality of clips  16  and slots  18 ,  20  to provide for a plurality of positions of the attenuator  14 . 
     The clips also provide some support to the attenuator  14 , particularly when it is in its “out” position. The cooperation between the slot  18 ,  20  and the clip  14  also provide some protection against unintentionally completely disengaging the attenuator  14  from the casing  12 . 
     In one embodiment, the attenuator clip  16  is made from high carbon spring steel. The attenuator clip  16  may be made from any material without departing from the spirit and scope of the invention. 
     The attenuator  14  and attenuator clips  16  of the present invention may also be used to retrofit existing terminal units, such as in a kit, depending on the geometry, component location, and other parameters of a particular existing terminal unit. 
     In one example of operation, the attenuator  14  is placed in the “in” position for shipping, storage, etc. When the terminal unit  10  is installed, or for testing, etc., the attenuator clips  16  engaging the slots  20  are disengaged and the attenuator  14  is repositioned to the “out” position. The attenuator clips  16  are then placed in engagement with the slots  18  to secure the attenuator  14  in the “out” position. If desired, the attenuator  14  may be completely removed from the casing  12  and the attenuator clips  16  not engaged with the slots  18 ,  20 . 
     The attenuator  14  may be replaced in the “in” position by disengaging the attenuator clips  16  from the slots  18 , repositioning the attenuator  14  to the “in” position, and engaging the attenuator clips  16  with slots  20 . 
     While the present invention has been illustrated by the above description of embodiments, and while the embodiments have been described in some detail, it is not the intention of the Applicants to restrict or in any way limit the scope of the invention to such detail. Additional advantages and modifications will readily appear to those skilled in the art. For example, the attenuator  14  could be arranged to cooperate with the top or bottom of the casing  12  such that the attenuator  14  is repositionable vertically. Or the attenuator  14  could be arranged to cooperate with a side of the casing  12 , instead of the rear of the casing  12 , as illustrated and described. Therefore, the invention in its broader aspects is not limited to the specific details, representative apparatus and methods, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of the Applicants&#39; general or inventive concept.