Abstract:
A duct detector includes sampling tubes which slidably engage the detector with a fixed orientation to facilitate fluid flow. The tubes have a connector portion and a conduit portion. The connector portion and the conduit portion engage one another with a predetermined orientation.

Description:
FIELD 
       [0001]    The invention pertains to duct-type detectors. More particularly, the invention pertains to such detectors with sample tubes that can be readily installed with an appropriate orientation without tools. 
       BACKGROUND 
       [0002]    It&#39;s been recognized that duct mountable ambient condition detectors can be useful in ambient condition monitoring systems, such as fire detection systems. Such detectors, which might respond to airborne smoke or gases, can be coupled to ducts which might be part of an HVAC which extends through a building or region being monitored. Such detectors are disclosed for example in Berneau et al., U.S. Pat. No. 6,124,795 entitled Detector Interconnect System which issued Sep. 26, 2000, and which is assigned to the assignee hereof, as well as Fenne Design Patent DES. 327,228 which issued Jun. 23, 1992, and is also assigned to the assignee hereof. The &#39;795 and &#39;228 patents are incorporated herein by reference. 
         [0003]    Known duct detectors require one or more tubular conduits to redirect air from inside the associated duct, part of a building ventilation system, to the detector. The conduits or sampling tubes are formed with openings aligned along their length. The openings allow air to flow down the tube to the detector and return again to the system. 
         [0004]    To ensure proper operation of the detector the openings must be aligned with the oncoming flow inside the system. The conduit must therefore be coupled to the detector housing or enclosure in a way that provides correct alignment and is secure to prevent disengagement or movement after installation. 
         [0005]    Known configurations used to couple the conduits to detector housings or enclosures tend to be cumbersome and time consuming to install. Fasteners are often used to retain the sampling tubes. These usually require the use of hand tools and can be difficult to work with in the small dark spaces the detectors are frequently installed. Often the detector cover must be removed to install the tubes and gain access to the fasteners, adding to the time and effort required for installation. Should the sampling tubes be installed in the wrong position the cover must again be removed to release the tube and reposition it correctly. 
         [0006]    One known coupling device is a formed flange fitted around the outer diameter of the conduit and fixed in place by a weld or a fastener as illustrated in  FIG. 1A &amp; 1B . Another is a rectangular tab formed into the end of the conduit that is guided through slots and aligned with notches in the detector housing as in  FIG. 2 . 
         [0007]    Both of the configurations of  FIGS. 1A ,  1 B and  2  have disadvantages. Specialized production equipment is required to attach a separate flange or punch and form a tab. The equipment can be costly to purchase, require frequent maintenance, and may have high operating cost. A formed tab protruding from the end of the tube may be sharp and could injure an operator producing the tubes or a technician handling them during installation. An improved coupler design which eliminates the need for fastening or welding and utilizes less costly production equipment would be desirable. 
         [0008]    Many man-hours could be saved and installation costs reduced if the coupling of these tubes was simple, quick, and did not require the use of tools or removal of the detector cover. In addition, insertion from both sides would be desirable. 
         [0009]    HVAC systems used to condition air-within a building and often contain cooling coils, and humidifiers which expose the detector and sampling tubes to moisture. Condensation on the any surface of the sampling tubes could collect inside the detector and cause the detector to malfunction. Current sampling tube designs do little to prevent condensation from entering the detector enclosure. It would be desirable to provide a coupler that would route small amounts of moisture away from the detector and prevent accumulation in the enclosure. 
     
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0010]      FIGS. 1A ,  1 B taken together illustrate one form of a prior art sampling tube; 
           [0011]      FIG. 2  illustrates another form of a prior art sampling tube; 
           [0012]      FIG. 3  illustrates a sampling tube in accordance with the present invention; 
           [0013]      FIGS. 4A ,  4 B taken together illustrate another sampling tube in accordance with the invention; 
           [0014]      FIGS. 5A ,  5 B taken together illustrate yet another sampling tube in accordance with the invention; 
           [0015]      FIGS. 6A ,  6 B taken together illustrate yet another form of a sampling tube in accordance with the invention; 
           [0016]      FIGS. 7A ,  7 B,  7 C illustrate yet another form of a sampling tube in accordance with the invention; 
           [0017]      FIGS. 8A ,  8 B taken together illustrate yet another form of a sampling tube in accordance with the invention; 
           [0018]      FIG. 9  illustrates various aspects of a process for attaching a conduit to a connector to form a sampling tube; 
           [0019]      FIG. 10A  illustrates attachment of the sampling tube from the back side of the enclosure; 
           [0020]      FIG. 10B  illustrates attachment of the sampling tube from the front of the enclosure after removal of the cover; 
           [0021]      FIG. 10C  illustrates some of the details of the sampling tube attachment structure; and 
           [0022]      FIGS. 11A ,  11 B taken together illustrate condensation elimination paths formed in sampling tubes in accordance with the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0023]    While embodiments of this invention can take many different forms, specific embodiments thereof are shown in the drawings and will be described herein in detail with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention, as well as the best mode of practicing same, and is not intended to limit the invention to the specific embodiment illustrated. 
         [0024]    Sampling tubes which embody the present invention can in one aspect provide a visual indication of proper alignment with the oncoming air flow, facilitate coupling and uncoupling to the detector enclosure in a less laborious and time consuming fashion than previous designs, and eliminate the need for fasteners or hand tools. Embodiments of the present coupler also provide protection against the ingress of water into the detector due to condensation on the surface of the tubes. 
         [0025]    In another aspect of the invention, the present coupler can be injection molded of a durable thermoplastic. Such couplers could include integral, molded, features for permanent assembly to a tubular conduit, coupling to a detector enclosure, and alignment to the oncoming flow. Several embodiments of couplers that embody the present invention are described below. 
         [0026]    One embodiment of a coupler contains an integral flexible member or cantilever snap that would mate with an opening in the conduit. The mating feature could be a hole, drilled or punched through the outer surface of the conduit. 
         [0027]    Another embodiment of the coupler would include a threaded connection. The coupler could be produced with integral threads on either an internal or external surface. The conduit could contain a formed feature to engage the molded threads as the coupler is rotated onto the ends of the conduit similar to a threaded pipe fitting. The coupler could also be designed for a press fit to the conduit. 
         [0028]    A preferred coupler embodiment would be one that easily assembles without tools. This could be accomplished by forming a detail in the conduit wall which fits into a mating opening in the coupler. The conduit could be formed prior to assembly of the coupler or after. 
         [0029]    The coupler could be designed such that a portion of the inner diameter would interfere with the formed detail. The coupler could be assembled over the end of the tube by hand to the point where the mating features are in contact, placed into a fixture, and pressed into final position. The parts would snap together, permanently attaching one to the other. 
         [0030]    The forming operation could, in another embodiment, be performed after the coupler has been assembled to the tube through an opening in the coupler or on the outside surface of the conduit. A secondary process could be used to create a deformation or a recess. Either could be formed without piercing the tube wall or punching a hole. 
         [0031]    Once assembled the conduit and coupler form a sampling tube which is then coupled to the enclosure of the duct detector. The detector enclosure includes a housing and cover, which are sealed to prevent mixing of air from inside and outside the HVAC system. A smoke or gas sensor is carried in the housing. The detector housing includes integral ports designed to receive the sampling tubes from either side of the enclosure. 
         [0032]    Installation from the back of the enclosure eliminates a need to remove the detector cover thereby simplifying the installation process and future replacement. These ports have an internal bore that closely fits the predetermined shape of the coupler. The predetermined shape provides alignment of the tube to the airflow when the detector is mounted on a duct with one of the available orientations. An indicator on the coupler is pointed into the airflow and verifies the alignment. 
         [0033]    Each port contains one or more cantilevered latches to lock the coupler into place and prevent disengagement or inadvertent removal of the sampling tube. These latches are easily actuated by hand and allow easy removal of the tubes for cleaning or repositioning. 
         [0034]    The coupler also prevents or minimizes an accumulation of moisture in the detector enclosure. This is accomplished by providing a small amount of clearance between the mating surfaces of the coupler and conduit. The clearance provides a path away from the housing for condensation that has collected on the tube and is forced in the direction of the detector due to airflow in the duct. 
         [0035]      FIG. 3  illustrates a coupler  10  which can be connected to a hollow conduit  12 , which could include openings for inflow or outflow of ambient atmosphere as would be understood by those of skill in the art. The coupler  10  has an elongated, hollow cylindrical body  14  with an internal flow path  16 . 
         [0036]    The housing  14  carries first and second integrally formed flexible attachment elements or cantilever snaps  18   a,    18   b.  One of the snaps, such as  18   b,  could mate with an appropriately shaped opening in the conduit  12 . The other snap, such as  18   a,  could mate with a housing or an enclosure for a respective duct-type detector. The mating feature in the conduit  12  with which the snap  18   b  engages could be a hole or other opening which has been drill punched, molded or otherwise formed in the conduit  12 . 
         [0037]      FIGS. 4A ,  4 B illustrate a threaded form of a coupler  10 - 1  which can rotatably engage a respective hollow conduit  12 - 1 . As illustrated in  FIGS. 4A ,  4 B a hollow body portion  14 - 1  of coupler  10 - 1  includes a set of internal integrally molded threads  18 - 1  which rotatably engage a feature  12   a - 1  formed on an end  12   b - 1  of the conduit  12 - 1 . 
         [0038]    The coupler  14 - 1  can be rotated onto the conduit  12 - 1 , best seen in  FIG. 4B , through the engagement of the threads  18 - 1  and the feature  12   a - 1 . End  14   a - 1  can slideably engage and latch, using latches such as the latches  18   a  of  FIG. 3 , to a respective housing or enclosure of a duct detector. 
         [0039]      FIGS. 5A ,  5 B illustrate an embodiment of a coupler  10 - 2  which engages a respective conduit  12 - 2  with a press fit or interference fit. The coupler  10 - 2  is hollow with an internal channel  16 - 2 . 
         [0040]    The coupler  10 - 2  has a detector end  14   a - 2  which carries an engagement feature, or features  14   c - 2  which slideably engage with and lock to a respective detector housing or enclosure. 
         [0041]    The coupler  10 - 2  has a displaced conduit related end  14   b - 2  which could be tapered and/or carry engagement features  14   d - 2  to slideably engage an internal channel  12 - 2   a  of the conduit  12 - 2 . As illustrated in  FIG. 5B , when the end  14   b - 2  is press fit into the channel  12 - 2   a  of the conduit  12 - 2  the housing or enclosure end  14   a - 2  continues to be exposed so as to be slideably engageable with the respective detector after the coupler  10 - 2  and the conduit  12 - 2  have been assembled together. 
         [0042]      FIGS. 6A ,  6 B illustrate a preferred embodiment for aligning and locking a coupler  10 - 3  to a respective conduit  12 - 3 . 
         [0043]    The coupler  10 - 3  has first and second spaced apart ends  14   a - 3 ,  14   b - 3 . As is the case with the couplers discussed previously, the coupler  10 - 3  is hollow with an internal flow channel  16 - 3 . A locking feature, such as a molded opening  14   c - 3  is carried adjacent to end  14   a - 3 . An alignment feature  14   d - 3  is formed in the end  14   b - 3  of coupler  10 - 3 . 
         [0044]    The conduit  12 - 3  carries an alignment and locking feature  12 - 3   c.  The coupler  10 - 3  is assembled to the conduit  12 - 3  by slideably engaging end  12 - 3   b.  The feature  12 - 3   c  is slid into engagement with the alignment feature  14   b - 3  either manually or with the use of a fixture as would be understood by those of skill in the art. A fixture could then be used to slide the body  14 - 3  of the coupler  10 - 3  onto the conduit  12 - 3  such that the feature  12 - 3   c  is slid through a channel  16 - 3  to the molded opening  14   c - 3  as a final position. The coupler  10 - 3  and the conduit  10 - 3  then snap together and are permanently attached to one another. 
         [0045]    Those of skill will understand that the features  12 - 3   c  and  14   c - 3  could be formed in a variety of shapes and orientations without departing from the spirit and scope of the present invention. Additionally, instead of a protrusion, feature  12 - 3   c  could be formed as a depression and the opening or port  14   c - 3  could be formed as an internally extending mating intrusion. It will be understood that the end  14   a - 3  of the coupler  10 - 3  could also carry detector housing engagement features such as  14   c - 2  of  FIG. 5A . 
         [0046]      FIGS. 7A ,  7 B and  7 C illustrate an alternate embodiment of a coupler  10 - 4  which is locked to a respective conduit  12 - 4  by a locking feature  20 - 4  formed in the end of the conduit  12 - 4 . In the embodiment of  FIGS. 7A-7C  the coupler  10 - 4  is slideably received over the hollow conduit  12 - 4  on the end  14 - 4   b.  In the embodiment of  FIGS. 7A-7C  the locking feature  20 - 4  is formed through an opening  14   d - 4  formed in an end  14   a - 4  of the coupler  10 - 4 . It will be understood that the opening  14   d - 4  illustrated having a rectangular aspect in  FIGS. 7A-7C  could be formed with a variety of shapes and configurations without departing from the spirit and scope of the invention. 
         [0047]    As illustrated in  FIG. 7B , the end  12 - 4   b  of the conduit  12 - 4  is positioned adjacent to the opening  14   d - 4 . Subsequently, a locking feature  20 - 4  is formed in the end  12 - 4   b  of the conduit  12 - 4 . The locking feature  20 - 4  engages a surface of the opening  14   d - 4  locking the conduit to the coupler  10 - 4 . The coupler  10 - 4 , as illustrated in  FIG. 7A-7C  can carry detector housing engagement features  14   c - 4  at the detector engagement end  14   a - 4 . 
         [0048]    Alternate configurations come within the spirit and scope of the present invention.  FIGS. 8A ,  8 B illustrate one such alternate. 
         [0049]    With respect to  FIGS. 8A ,  8 B a coupler  10 - 5  slideably engages a respective conduit  12 - 5 . A conduit receiving end  14   b - 5  of the coupler  10 - 5  carries a molded or formed feature or depression  14   c - 5 . 
         [0050]    When the conduit  12 - 5  is appropriately positioned on the end  14   b - 5 , as illustrated at  FIG. 8B , a depression or formed feature  12 - 5   c  can be formed on the end  12 - 5   b  of the conduit  12 - 5  thereby locking the conduit to the coupler. The feature  12 - 5   c  engages the depression  14   c - 5  of the coupler. Prior to forming the feature  12 - 5   c  the radial location of the conduit  14 - 5  and the axially located openings thereon (to permit ingress and egress of the ambient atmosphere being sensed) is established relative to the detector housing locking features  14   d - 5  of the coupler  10 - 5 . 
         [0051]      FIG. 9  illustrates cross-sectional views of the conduit, such as conduit  12 - 5 , and coupler, such as the coupler  10 - 5 , after the locking feature, such as the feature  12 - 5   c  of  FIG. 8B , has been formed to lock the conduit to the respective coupler. 
         [0052]      FIGS. 10A-10C  illustrate aspects of engagement of an assembled sampling tube, such as the embodiment illustrated in  FIGS. 6A ,  6 B discussed above coupled to a housing or enclosure  32  of the duct-type detector  30 . Those of skill in the art will understand the enclosure  32  contains an interior region which carries an ambient condition detector, such as a smoke or gas sensor  34 . 
         [0053]    The housing  32  also carries at least one and preferable two ports such as the port  36 ,  36 ′ to which the sampling tube  38  is attached. Sampling tube  38  could correspond to any of the previously discussed embodiments without limitation. For discussion, the sampling tube  38  corresponds to the preferred embodiment of coupler  10 - 3  and conduit  12 - 3  of  6 A,  6 B without limitation. 
         [0054]    In  FIG. 10A , the respective sampling tube  38  is illustrated being slideably attached to an exterior part  36  of the port  36 ,  36 ′ which is extending from a rear external surface  32   a  of the enclosure or housing  32 . With the configuration of  FIG. 10A  the sampling tube  38  can be slid into position in the port  36 ,  36 ′ to slideably engage a snap lock element  36   a  without having to remove a front cover or panel of the housing  32 . 
         [0055]    The port  36 ,  36 ′ is formed with a predetermined internal cross-section  36   b  which permits the coupler  10 - 3  to be inserted thereinto only with selected orientations. The combination of the exterior cross-sectional shape of the coupler  10 - 3 , and the internal cross-section  36   b  of the port  36  insures that the openings in the conduit  12 - 3  (intended to receive either inflowing or outflowing ambient atmosphere) are properly aligned relative to the orientation of the housing  32 . A visual indicator can be carried on the coupler  10 - 3 , for example, to provide visual confirmation that the axially oriented openings in the conduit  12 - 3  are properly aligned with the expected direction of flow of ambient atmosphere in the respective duct. 
         [0056]    One or more latches corresponding to the latch  36   a  can be provided in the port  36 ,  36 ′. The latch or latches  36   a  lock the coupler  10 - 3  to the housing  32  and prevent disengagement or inadvertent removal thereof. The latch or latches  36   a  are readily actuatable by hand, without any need for tools. The respective coupler/conduit combination, such as the sampling tube  38 , can be readily removed for cleaning or repositioning depending on the requirements. 
         [0057]      FIG. 10B  illustrates installation of the respective sampling tube  38  where the cover has been removed from the housing  32 . In this instance, the conduit  12 - 3  is slid through the interior portion  36 ′ of the port  36 , 36 ′ and the coupler  10 - 3  subsequently slideably engages the respective latch or latches such as the latch  36   a.  It will be understood that the interior form  36  of  FIG. 10A  could be identical to the interior  36 ′ of  10 B without departing from the spirit and scope of the present invention. Alternately, the portions of the port  36 ,  36 ′ could be configured differently from one another. In the installation illustrated in  FIG. 10B , once the sampling tube  38  has been inserted through the interior  36 ′ and locked into place, as described previously, the detector  30  would be closed by a front panel or cover not illustrated. 
         [0058]    As illustrated in  FIG. 11A , hollow conduit  12 - 3  which has been slideably received in coupler  10 - 3  together define an annular space  50  which extends along an external periphery of the conduit  12 - 3  and along an interior periphery of the coupler  10 - 3 . This clearance between those surfaces provides a pathway for condensation, which may collect on the conduit  12 - 3 , to flow away from the housing  30 . This process can be enhanced by, as illustrated in  FIG. 11B , by molding channels  52   a,    52   b  into the internal peripheral surface  16 - 3  of the coupler  10 - 3 . 
         [0059]    One or more spacers  54  can also be molded into the end  14   a - 3  of the coupler  10 - 3  to offset an end surface  12 - 3   e  of the conduit  12 - 3  from an annular end surface  56  of the coupler  10 - 3 . This space provides an additional part of the condensation exit path. 
         [0060]    The condensation can then exit along the internal channel  12 - 3   a  of the conduit  12 - 3 . The subject condensation tends to collect on the exterior surface of the tube or conduit  12 - 3  and then is forced toward the housing  30  of the detector due to airflow in the duct. 
         [0061]    From the foregoing, it will be observed that numerous variations and modifications may be effected without departing from the spirit and scope of the invention. It is to be understood that no limitation with respect to the specific apparatus illustrated herein is intended or should be inferred. It is, of course, intended to cover by the appended claims all such modifications as fall within the scope of the claims.