Abstract:
A plenum assembly for carrying air in a supply system includes a duct including an opening formed with an inner surface through which air can flow; a door supported for movement between multiple positions which distributes air to the desired output path; and a seal secured to the door. In a vehicles HVAC system, numerous doors are utilized to provide comfort to the passengers based upon user input. The potential exists that some positions of the doors my lead to unwanted noise. A modification to the seal of the door with variable gap widths alleviates this issue and improves satisfaction.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    This invention relates generally to an apparatus for opening and closing connections among passages that carry air in a heating, ventilation and air conditioning (HVAC) plenum. 
         [0003]    2. Description of the Prior Art 
         [0004]    A plenum assembly for carrying air in a supply system includes a duct with an inner surface through which air can flow and a door supported for movement between a multitude of open positions, at which flow through the opening is relatively unobstructed, and a sealed position, at which flow through the opening is relatively obstructed. Some positions of the door produce a small gap between the seal and the inner duct surface. The present invention includes a modification to the seal in which this gap has a continuously variable width along at least a portion of a length of the seal. 
         [0005]    The variable edge profile provides a gap having a variable width and prevents uniform airflow over the seal. As a result, objectionable high frequency tones and whistles are prevented without compromising the functionality of the seal. 
         [0006]    A need exists in the industry for a technique that prevents objectionable noise when the door moves near the sealed position. 
       SUMMARY OF THE INVENTION 
       [0007]    A plenum assembly for carrying air in a supply system includes a duct including an opening formed with a inner surface through which air can flow; a duct including an opening formed with a inner surface through which air can flow; a door supported for movement between a sealed position, at which flow through the opening is relatively unobstructed, and a partially sealed position, at which flow through the opening is relatively obstructed; and a seal secured to the door and producing in the partially sealed position a gap between the seal and the inner surface, the gap having a continuously variable width along at least a portion of a length of the seal. 
         [0008]    The variable edge profile on the edge of overmold door seals provides a gap having a variable width and prevents uniform airflow over the seal. As a result, objectionable high frequency tones and whistles are prevented without compromising the functionality of the seal. 
         [0009]    The scope of applicability of the preferred embodiment will become apparent from the following detailed description, claims and drawings. It should be understood, that the description and specific examples, although indicating preferred embodiments of the invention, are given by way of illustration only. Various changes and modifications to the described embodiments and examples will become apparent to those skilled in the art. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0010]    The invention will be more readily understood by reference to the following description, taken with the accompanying drawings, in which: 
           [0011]      FIG. 1  is a front view of a duct showing a door and seal assembly in relation to the duct walls; 
           [0012]      FIG. 2  is side view the door, seal and shaft showing a first door in its partially sealed position and a second door in its sealed position; 
           [0013]      FIG. 3  is a side view of the door, seal and shaft showing the first door in its sealed position and the second door in its partially sealed position; 
           [0014]      FIG. 4  is a rear view showing the stiffeners at the back of the door; 
           [0015]      FIG. 5  is a perspective view of the back of the door; 
           [0016]      FIG. 6  is a front view of a second embodiment in which the door has a contoured edge and the seal has uniform width; and 
           [0017]      FIG. 7  is a front view of a third embodiment in which the door and seal have straight edges and the duct is contoured. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0018]    Referring now to the drawings, there is illustrated in  FIG. 1  a plenum assembly that includes a duct  12 , which carries air in a HVAC system for an automotive application. The duct  12  has been cross sectioned by a transverse plane normal to the length of the duct. An inner surface  14  and an outer surface  16  of the duct  12  are formed with substantially flat surfaces, along which air flows longitudinally in the duct. 
         [0019]    A door assembly includes two doors  18 ,  19 , supported on a shaft  20 , which rotates about an axis  22 . Each door  18 ,  19  rotates with shaft  20  to a respective sealed position, the sealed position of each door being located at an end of the door&#39;s rotary travel. The doors  18 ,  19  direct air in the duct to selected paths, through which air is delivered from the duct to the passenger compartment of the vehicle. 
         [0020]    The doors  18 ,  19  are preferably formed of a rigid material, while the seal surrounding and secured to the periphery  26  of the door  18 ,  19  is preferably formed of a relatively soft thermoplastic. This variable design may also be added to the perimeter of a door which does not utilize a thermoplastic seal. 
         [0021]      FIG. 1  shows shaft  20  having been rotated about axis  22  to the sealed position of door  18 , at which the door  18  and seal  24  substantially obstruct and prevent air flow in duct  18  past the seal and door. 
         [0022]    When shaft  20  rotates about axis  22  in either rotary direction to a position at which door  18  and seal  24  are spaced angularly about five degrees from the duct opening, the door and seal are in a partially sealed position. When the door  18  and seal  24  are in the partially sealed position, air can flow in duct  12  through a small gap  28  between the duct&#39;s inner surface  14  and the seal&#39;s periphery  30 . In the partially sealed position, air flow past the seal  24  is partially obstructed, but air flow is substantially greater compared to any flow that may occur past seal  24  when door  18  and seal  24  are in their sealed position. 
         [0023]    Similarly, shaft  20  can rotate doors  18 ,  19  about 100 degrees away from the sealed position of door  18  to the sealed position of door  19 , at which door  19  and seal  24  substantially obstruct and prevent air flow in duct  18  past door  19  and seal  24 . 
         [0024]    When shaft  20  rotates about axis  22  in either rotary direction to a position at which door  19  and seal  24  are spaced angularly about five degrees from the duct opening, door  19  and seal  24  are in their partially sealed position. When door  19  and seal  24  are in their partially sealed position, air can flow in duct  12  through a small gap between the duct&#39;s inner surface  14  and the seal&#39;s periphery  30 . In the partially sealed position, air flow past the seal  24  is partially obstructed but air flow is substantially greater compared to any flow that may occur when door  19  and seal  24  are in their sealed position. 
         [0025]      FIG. 2  is side view showing door  18  in its partially sealed position, i.e., spaced a short distance from the inner surface  14  of duct  12 , and door  19  in its sealed position contacting surface  14 .  FIG. 3  is a side showing door  18  in its sealed position, i.e., contacting the inner surface  14  of duct  12 , and door  19  in its partially sealed position, spaced a short distance from the inner surface  14 . 
         [0026]    In a first embodiment, the seal&#39;s periphery  30  is a continuous series of arcuate segments or angular projections forming a border of serrations, preferably a series of ridges  32  and grooves  34  along the peripheral length of the seal  24  and extending across the thickness  36  of the seal  24 , as shown in  FIG. 2 . Preferably the distance between consecutive ridges  32  and grooves  34  is random and non-uniform along the peripheral length of the seal  24 , although that spacing may be uniform. Similarly, the height of the ridges  32  and the depth of the grooves  34  are preferably random, although those heights and depths may be uniform along the peripheral length of the seal  24 . 
         [0027]      FIGS. 2 ,  3 ,  4  and  5  show that the right-hand side of shaft  20  is formed with external teeth  42 , and the left-hand side is formed with internal teeth  40 , and the back of door  18 , which faces downstream, is supported by a series of stiffeners  44 ,  46 ,  48 , spaced mutually across the width of the door. 
         [0028]    In the embodiment of  FIGS. 1-5 , the serration formed by the ridges  32  and grooves  34  causes the gap  28  between the seal&#39;s periphery  30  and the duct&#39;s inside surface  14  to be non-uniform along the peripheral length of the seal  24 . The variable profile of the gap  28  prevents uniform airflow across the seal&#39;s thickness  36  and along the peripheral length of the seal  24 . As a result, objectionable high frequency tones and whistles are prevented without compromising the functionality of the seal. 
         [0029]    In the second embodiment shown in  FIG. 6 , the edge  50  of a door  52  is formed with a continuous series of arcuate segments or projections forming serrations, preferably a series of ridges  54  and grooves  56 . A seal  58  formed of relatively soft, vulcanized thermoplastic surrounding and secured to the door&#39;s edge  50 , has a uniform width  60  and straight sides before being installed on the door&#39;s edge  50 . Upon installation, the seal&#39;s periphery  62  conforms to the contour of the door&#39;s edge  50 . A gap  64  between the inner surface  14  of the duct  12  and the seal&#39;s periphery  62  is a continuous series of arcuate segments or projections forming serrations, preferably a series of ridges and grooves similar to those on the door&#39;s edge  50 . Preferably the width of gap  64  is random and non-uniform along the peripheral length of the seal  58 . This embodiment may also be utilized where the edge  50  of a door  52  does not have a seal attached, but has a series of ridges  54  and grooves  56 , which eliminate the uniformity of air passing by. 
         [0030]    The door  58  is supported on shaft  20  and rotates with the shaft about axis  22  to the sealed and partially sealed positions. The door  52  is preferably formed of a rigid, polypropylene plastic containing mica. 
         [0031]    Serrations formed by the ridges  54  and groove  56  cause the gap  64  between the seal&#39;s periphery  62  and the inner surface  14  of duct  12  to be non-uniform along the length of the seal. The variable width of gap  64  prevents uniform airflow across the seal&#39;s thickness  36  and along the peripheral length of the seal  58 . Objectionable high frequency tones and whistles are prevented without compromising the function of the seal  58 . 
         [0032]    In the third embodiment shown in  FIG. 7 , the inner surface  60  of the duct  62  is formed with a continuous series of arcuate segments or projections forming serrations, preferably a series of ridges  64  and grooves  66 . A seal  68 , formed of relatively soft, vulcanized thermoplastic surrounding and secured to the straight outer edge  70  of the door  72 , has a straight outer edge  74 , which extends along the peripheral length of the seal. 
         [0033]    The width of the gap  74  between the inner surface  60  of the duct  62  and the seal&#39;s periphery  74  is continuously variable along the peripheral length of the seal  68 . The variable width of gap  64  prevents uniform airflow across the seal&#39;s thickness  36  and along the peripheral length of the seal  68 . As a result, objectionable high frequency tones and whistles are prevented without compromising the function of the seal  68 . 
         [0034]    The door  18 ,  52 ,  72  may rotate about axis  22 , which may be located and directed such that the door pivots to the sealed position downward from above the door or upward from below the door, as shown in  FIGS. 1-5 , or leftward or rightward. Alternately, the door may slide on a rail or in a track between the sealed and partially sealed positions. 
         [0035]    In accordance with the provisions of the patent statutes, the preferred embodiment has been described. However, it should be noted that the alternate embodiments can be practiced otherwise than as specifically illustrated and described.