Abstract:
A gas flow regulator comprises a gas passage duct that can be axially repositioned and rotationally reoriented relative to a chamber wall for controlling the flow rate of gas from one side of the wall into an interior volume on an opposite side of the wall. The flow regulator provides a simplistic and cost effective way of regulating the gas flow rate though a test chamber wall by merely axially and rotationally reorienting the gas passage duct relative to the wall.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    (1) Field of the Invention  
           [0002]    This invention pertains to the field of gas flow regulators in thermodynamic environmental testing devices. More particularly, this invention pertains to a gas flow regulator comprising a gas passage duct that can be axially repositioned and rotationally reoriented relative to a chamber wall for controlling the flow rate of gas into the interior volume of a thermodynamic environmental testing chamber for increasing the spatial uniformity of the rate of temperature change throughout test specimens tested in the chamber. The flow regulator of the invention provides a simplistic and cost effective means of regulating the gas flow rate though a test chamber wall by merely axially and rotationally reorienting a gas passage duct relative to the cavity wall.  
           [0003]    (2) Description of the Related Art  
           [0004]    Thermodynamic environmental testing devices are used in various industries, primarily for testing the fatigue properties of test specimens, and operate by cycling the temperature of such test specimens. Testing devices typically comprise a large thermodynamically insulated box-like unit having one or more doors that provide access to an internal testing chamber therein. Heating and cooling of test specimens placed within the testing chamber is achieved by supplying heated or cooled gas into the chamber through ports communicating with the chamber interior volume. Using liquid nitrogen for cooling and electric heating elements for heat, the temperature change rates of test specimens can exceed 70° Celsius per minute.  
           [0005]    During operation, the temperature of gas flowing into the testing chamber of a testing device is commonly controlled by an electronic control module. Among other things, such control modules typically allow control of the temperature change rates, the maximum and minimum testing chamber temperature, and the maximum and minimum temperature of gas being supplied into the testing chamber. This is done by programming the control module with specific temperature cycling parameters and by providing the control module with feedback of monitored testing chamber temperatures. Such control modules are also typically interfaced with heating, cooling, and blower systems for controlling such systems in an effort to achieve the programmed cycling parameters.  
           [0006]    The heated or cooled gas is typically delivered into the testing chamber via a plenum having one or more ports communicating with the chamber interior. The ports often comprise flexible hosing which allow the heated or cooled gas to be delivered to various locations within the testing chamber to improve the performance and efficiency of the testing device.  
           [0007]    Despite the ability to regulate the gas temperature and its overall flow rate into the testing chamber using prior art testing devices, it is difficult to achieve spatially uniform rates of temperature change throughout various test specimens or throughout portions of each test specimen. This is because various test specimens generally have various heat-sink properties and even a single test specimen can have different portions that require more or less total heat or cooling to achieve the same rate of temperature change as other portions thereof. Although directing the gas flow from each of the ports using flexible hoses helps reduce spatial variations of the rate of temperature change throughout the test specimens, the spatial variations of the rate of temperature change within the testing chambers of prior art testing devices is still problematic.  
           [0008]    The present invention overcomes the disadvantages associated with prior art thermodynamic environmental testing devices by providing gas flow regulators capable of independently adjusting the gas flow rate of heating or cooling gas flowing through a plurality of supply ports from one or more plenums into a testing chamber. By allowing independent adjustment of the gas flow through the plurality of ports, the total amount of heating or cooling gas flowing into the testing chamber can be distributed in a manner that reduces spatial variations of temperature change rates throughout one or more test specimens. Furthermore, a unique gas flow regulator is employed that comprises a minimal number of components and that is capable of adjusting gas flow through a test chamber wall by merely adjusting its position and orientation relative to a portion of the cavity wall.  
         SUMMARY OF THE INVENTION  
         [0009]    In its intended operative environment, the gas flow regulator of the invention is employed with a thermodynamic environmental testing chamber of the type described earlier. Apart from the presence of the novel gas flow regulator of the invention, the thermodynamic environmental testing chamber is constructed as any typical testing chamber.  
           [0010]    The chamber has an exterior housing with an interior volume employed in testing specimens that are enclosed in the housing of the chamber. The housing includes one or more doors that provide access to the interior volume of the chamber. In addition, a plenum is provided inside the chamber housing. The plenum extends around opposite sides of the interior volume of the chamber and is supplied with a flow of gas from a source of the type described earlier. The gas flow through the plenum is either cooled or heated as desired for the particular test being conducted in the chamber. The plenum encloses a second, interior volume through which the gas flow passes. The second interior volume is enclosed by at least a first wall and a second wall of the plenum. The first wall of the plenum is provided with the supply ports that communicate the second volume of the plenum interior with the first volume of the chamber interior containing the test specimens.  
           [0011]    As set forth above, the gas flow regulator of the invention is used in the typical thermodynamic environmental testing chamber described above in its preferred operative environment. However, it should be apparent that the simplistic construction and operation of the gas flow regulator of the invention may be employed in other similar environments where it is desired to provide a low cost and simple to operate regulator that adjusts the flow of gas from one volume on one side of a wall to another volume on an opposite side of the wall. To explain the construction and the operation of the gas flow regulator of the invention, the illustrative embodiment of the thermodynamic environmental testing chamber will be employed.  
           [0012]    In the illustrative embodiment of the gas flow regulators, the gas flow supply ports in the plenum first wall separating the first volume of the test chamber interior from the second volume of the plenum interior are circular. The simplistic construction of each gas flow regulator is comprised of a cylindrical duct and a locking mechanism. The cylindrical duct has a selected length with opposite first and second ends. A cylindrical interior surface of the duct defines a passageway through the duct having a center axis. The exterior surface of the duct is cylindrical and has a circumferential dimension that matches the interior circumferential dimension of the holes of the ports in the first wall of the plenum so that the duct may be inserted into one of the holes in a tight friction fit. This enables the duct to slide within the hole while the edge of the plenum first wall around the hole provides support for the duct. The first end of the duct has an annular edge that lies in a plane perpendicular to the duct center axis. The opposite second end of the duct is beveled in shape. Preferably, the second end of the duct has an elliptically shaped edge that lies in a plane that is oriented obliquely to the duct center axis.  
           [0013]    The gas flow regulator is assembled to the test chamber by the duct being inserted through one of the holes in the first wall of the plenum. The duct is positioned in the hole with the first end of the duct positioned in the first volume of the test chamber interior and the second end of the duct positioned in the second volume of the plenum interior. A gas flow regulator is assembled into each of the holes of the plenum ports.  
           [0014]    The locking mechanism of the gas flow regulator is preferably an adjustable band clamp of the type known in the prior art. As in the typical band clamp, the band clamp of the regulator has opposite ends with slots formed across one end that function as rack teeth and a screw housing containing an adjustment screw at the opposite second end. The band first end is inserted through the screw housing forming the band in a loop, and on rotation of the screw in the screw housing the threads of the screw pass through slots of the band first end adjusting the size of the loop formed by the band.  
           [0015]    The band of the locking mechanism is positioned over the exterior surface of the duct in the first volume of the test chamber interior where it is accessible from the test chamber. The screw housing of the locking mechanism is secured to the plenum first wall to hold the locking mechanism stationery relative to the first wall. By screwing the screw in the screw housing of the locking mechanism, the band is constricted around the duct and thereby holds the duct in a stationery position relative to the first wall of the plenum.  
           [0016]    In the illustrative environment of the invention, a gas flow regulator is positioned in each hole in the air plenum first wall to regulate the flow of gas through the second volume of the plenum interior to the first volume of the test chamber interior.  
           [0017]    In operation of the test chamber employing the flow regulator of the invention, the test chamber is activated causing a flow of gas (either heated or cooled) through the second volume of the plenum interior. It is typical that the flow of gas be directed in a single direction from the source of the gas flow toward the holes in the first wall of the plenum. The duct of the gas flow regulator positioned in each of the first wall holes channels the gas from the interior volume of the plenum through the passageway of the duct, and into the interior volume of the test chamber.  
           [0018]    With the duct second end in the interior volume of the plenum having a beveled edge, rotating the duct in the plenum wall hole so that the elliptical opening of the beveled edge faces into the flow of gas through the plenum will result in a greater amount of the gas flow being channeled through the passageway of the duct and into the test chamber interior. Turning the duct  180  degrees in the plenum wall hole so the elliptical opening of the beveled edge faces away from the flow of gas will adjust the flow of gas through the passageway of the duct, decreasing the flow. In addition, with the interior volume of the plenum being defined between the first wall of the plenum that supports the gas flow regulator ducts and the second wall of the plenum that is positioned on the opposite side of the plenum interior volume from the first wall, moving each regulator duct axially so that the second end of the duct is spaced further away from the second wall of the plenum will increase the area between the duct second end and the plenum second wall and enhance the free flow of gas supplied through the plenum interior volume to the duct and through the duct passageway into the test chamber interior volume. Conversely, moving each duct axially through the hole of the plenum first wall toward the second wall of the plenum so that the duct second end is positioned closer to the plenum second wall decreases the area between the duct second end and the plenum second wall and restricts the free flow of gas supplied through the plenum to the duct and through the duct passageway into the test chamber interior volume.  
           [0019]    Thus, by rotating each duct in its hole of the plenum first wall and by axially adjusting the position of each duct in its hole in the plenum first wall the rate of gas flow through each duct passageway from the plenum interior volume to the test chamber interior volume can be adjusted. When the desired rate of gas flow through each duct passageway is achieved, the duct can be held in its adjusted position by tightening the screw of the locking mechanism, thereby holding the duct stationery in its adjusted position relative to the plenum wall.  
           [0020]    By providing a plurality of holes in the plenum first walls on the opposite sides of the test chamber interior volume and a plurality of gas flow regulators of the invention mounted in the holes, the flow of gas from the plenum interior volume into different portions of the test chamber interior volume can be adjusted, thereby achieving a means of obtaining a more spatially uniform rate of temperature change throughout various test specimens or throughout various portions of a test specimen positioned in the interior volume of the test chamber.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWING FIGURES  
       [0021]    Further features of the invention are set forth in the following detailed description of the preferred embodiment of the invention and in the following drawing figures wherein:  
         [0022]    [0022]FIG. 1 is a front elevation view of a typical thermodynamic environmental testing chamber employing the gas flow regulators of the invention;  
         [0023]    [0023]FIG. 2 is an assembly view of the gas flow regulator of the invention illustrating its assembly to a plenum of the test chamber of FIG. 1;  
         [0024]    [0024]FIG. 3 is a partial, cross-section view of the gas flow regulator of the invention assembled to the plenum of the test chamber of FIG. 1; and  
         [0025]    [0025]FIG. 4 is a partial, cross-section view similar to that of FIG. 3 but showing the gas flow regulator in another adjusted position of the regulator relative to the plenum. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0026]    [0026]FIG. 1 shows a front elevation view of the operative environment of a thermodynamic environmental testing chamber with which the gas flow regulator of the invention may be employed. However, it should be understood that the operative environment shown in FIG. 1 and to be described is not intended to limit the gas flow regulator of the invention with use only in the environment of the testing chamber. The simplistic construction of the gas flow regulator may be employed in a variety of other environments where it is desired to provide a means of controlling or regulating the flow of a fluid from a volume on one side of a dividing wall to another volume on the opposite side of the dividing wall by means of an inexpensively manufactured and installed and an easily operated control device.  
         [0027]    The construction of the thermodynamic environmental testing chamber  10  shown in FIG. 1 is, for the most part, conventional apart from the presence of the novel gas flow regulator  12  of the invention. Therefore, the testing chamber  10  will be described in only general detail.  
         [0028]    As seen in FIG. 1, the thermodynamic environmental testing chamber  10  is basically comprised of a large box-shaped housing having a bottom wall structure  14  and an opposite top wall structure  16 , a left side wall structure  18  and an opposite right side wall structure  20  as viewed in FIG. 1, a back wall structure  22  and a front opening  24  providing access into a first volume  26  of the test chamber interior. One or more doors  28  are connected to the front of the chamber  10  and close over the front opening  24  to seal closed the chamber interior volume  26 . The wall structures and the doors are typically thermally insulated. A plurality of viewing windows  30  are often provided in the doors and one or more of the chamber wall structures. A specimen platform  32  is provided in the chamber interior  26  for supporting one or more specimens to be tested. Heating or cooling of test specimens placed in the chamber interior  26  and supported on the platform  32  is provided by supplying heated or cooled gas to the chamber interior in a manner to be explained.  
         [0029]    The temperature of the gas and its rate of flow supplied into the test chamber interior  26  is controlled by an electronic control module  34 . Control modules  34  are typically interfaced with heating, cooling and blower systems (not shown) of the testing chamber  10  for controlling such systems to achieve the desired testing environment in the interior volume  26  of the test chamber.  
         [0030]    The typical test chamber  10  employs a plenum to direct the flow of gas generated by the test chamber to opposite sides of the chamber interior volume  26 . In the example shown in FIG. 1, the test chamber plenum is comprised of two sections  36  that extend downwardly across the opposite left side wall structure  18  and right side wall structure  20  in the interior volume  26  of the test chamber. Each of these plenum sections  36  encloses a second volume  38  that is supplied with a gas flow from the gas flow source (not shown) and directs the flow of gas through the interior volume of the plenum downwardly across the opposite sides of the chamber interior volume. Each plenum section  36  is basically comprised of a first wall  40  that is spaced by the second volume  38  in the interior of the plenum from a second wall  42  of the air plenum section that could be a portion of the test chamber left and right side wall structures  18 ,  20  or could be a separate wall from the side wall structures. As seen in FIG. 1, peripheral walls  44  space the first plenum wall  40  from the second plenum wall  42  and enclose the second interior volume  38  of the plenum. With the plenum sections  36  positioned against the opposite left and right side wall structures  18 ,  20  of the test chamber as shown in FIG. 1, the first plenum walls  40  separate the first volume  26  of the test chamber interior from the second volume  38  of the plenum interiors. The plenum first walls  40  are provided with one or more, and preferably a plurality, of port openings or holes  46  that provide communication between the first volume  26  of the chamber interior and the second volume  38  of the plenum interior. The holes  46  channel the flow of gas through the plenum second volume  38  through the holes to the first volume  26  of the chamber interior.  
         [0031]    The gas flow regulator  12  of the invention is used in the thermodynamic environmental testing chamber  10  described above in its preferred operative environment. However, as explained earlier, the gas flow regulator  12  of the invention may be employed in regulating the flow of gas from a second volume on one side of a wall to a first volume on the opposite side of the wall. The simplistic construction of the gas flow regulator  12  as shown in FIG. 2 is comprised of a duct member  48  and a locking mechanism  50 .  
         [0032]    The duct member  48  may be constructed of metal or plastic resins that are capable of withstanding the changes in temperature to which the duct will be subjected in use in the testing chamber. The duct  48  has a length between opposite first  52  and second  54  ends of the duct. The length of the duct between its opposite ends can be varied, depending on how far it is desired that the duct reach into the testing chamber interior volume  26  from the air plenum  36  as will be explained. A cylindrical interior surface  56  of the duct defines a passageway through the duct between its opposite ends. The interior surface  56  and the passageway it defines have a center axis  58  extending through the duct. The duct exterior surface  60  is also cylindrical and has a circumferential dimension or an exterior diameter dimension that matches the interior circumferential dimension or interior diameter dimension of a hole  46  or channeling port in the plenum first wall  40 . This dimensioning of the duct exterior surface enables it to be inserted into one of the holes  46  in the plenum first wall  40  in a tight friction fit. The tight fit of the duct  48  in the plenum hole  46  minimizes the leakage of the flow of gas from the plenum second volume  38  through the connection of the plenum hole inner edge  62  with the duct exterior surface while still allowing the duct  48  to slide within the hole  46  while the edge of the plenum first wall surrounding the hole provides support for the duct. In the preferred embodiment of the flow regulator, the duct first end  52  has a circular or annular edge  64  that lies in a plane perpendicular to the duct center axis  58 . In alternative embodiments, the shape of the duct first end  52  can be varied as desired for the purpose of directing gas flow from the duct first end or for other purposes. The opposite, second duct end  54  is beveled in shape. Preferably, the duct second end  54  has an elliptically shaped edge  66  that lies in a plane that is oriented obliquely to the duct center axis  58 . The beveled shape of the duct second end  54  forms the second end with a shroud projection  68  that projects out over the opening  70  of the duct passageway at the duct second end  54  as viewed in FIG. 2. The beveled shape of the duct second end  54  also gives the second end an exposed opening  70  to the duct passageway that faces away from the projecting shroud  68 .  
         [0033]    The gas flow regulator  12  is assembled to the test chamber  10  as shown in FIGS. 2 through 4. A regulator duct  48  is positioned in each of the holes  46  in the test chamber plenum first wall  40  by sliding the duct from the first volume  26  of the chamber interior through the hole  46  into the second volume  38  of the plenum interior. The duct is positioned in the hole with the duct first end  52  positioned in the first volume  26  of the test chamber interior and with the duct second end  54  positioned in the second volume  38  of the plenum interior volume as shown in FIGS. 2 through 4. With the tight friction fit of the hole interior edge  62  around the exterior surface  60  of the duct, the plenum first wall  40  supports the duct in the hole with the duct center axis  58  substantially perpendicular to the plenum first wall  40 .  
         [0034]    The locking mechanism  50  of the gas flow regulator is preferably an adjustable band clamp of the type known in the prior art. As in a typical band clamp and as shown in FIG. 2, the band  78  of the band clamp has opposite first  80  and second  82  ends with slots  84  formed into the first end of the band that function as rack teeth. A screw housing  86  containing an adjustment screw  88  is provided at the opposite, second end  82  of the band. The band first end  80  is inserted into the screw housing  86  forming the band in a loop, and on rotation of the adjustment screw  88  in the screw housing  86 , the threads of the screw pass through the slots  84  of the band first end adjusting the size of the loop formed by the band.  
         [0035]    The band  78  of the locking mechanism is positioned over the duct exterior surface  60  in the first volume  26  of the test chamber interior when the duct is assembled to the plenum first wall  40 , where the locking mechanism  50  is accessible from the test chamber interior. The screw housing  82  of the locking mechanism is secured to the plenum first wall  40  by a spot weld or other equivalent means to hold the locking mechanism stationary relative to the first wall. With the loop formed by the band  78  expanded, the duct  48  is still free to move axially through the plenum first wall hole  46  and rotationally in the hole. By screwing the adjustment screw  88  in the screw housing  86  of the locking mechanism, the band  78  can be constricted around the duct exterior surface  60  and thereby the locking mechanism holds the duct in a stationary position relative to the first wall  40  of the plenum.  
         [0036]    In the illustrative environment of the invention, a gas flow regulator  12  is positioned in each of the holes  46  in the first walls  40  of the plenum sections  36  on opposite sides of the first volume  26  of the test chamber to regulate the flow of gas through the plenum second volume  38  to the first volume  26  of the test chamber interior.  
         [0037]    In operation of the test chamber  10  employing the flow regulators  12  of the invention, with a flow regulator  12  positioned in each of the holes  46  of the plenum first walls  40 , the test chamber is activated causing a flow of gas (either heated or cooled) through the second volume  38  of the plenum interior. In the illustrative embodiment shown, the flow of gas is directed downwardly through the second volume  38  of the plenum interior toward the holes  46  adjacent the bottom of the plenum sections  36 . The duct  48  of each of the gas flow regulators  12  positioned in each of the plenum holes  46  channels the flow of gas from the plenum second volume  38 , through the duct passageway and into the interior volume  26  of the test chamber.  
         [0038]    With the duct second end  54  having a beveled edge  66 , rotating the duct in the plenum first wall  40  so that the exposed elliptical opening  60  of the beveled edge faces into the downwardly directed flow of gas through the plenum interior volume  38  as shown in FIG. 3 will result in a greater amount of gas being channeled through the passageway of the duct and into the test chamber interior volume  26 . This is due to the ramming effect of the flow of gas downwardly through the plenum interior  38  into the exposed elliptical opening  70  of the duct. By gradually rotating the duct  48  in the plenum first wall hole  46  so that the exposed opening  70  is gradually directed away from the flow of gas channeled downwardly through the plenum, the ram effect of the flow of gas on the exposed opening  70  is decreased and the flow of gas through the duct is also decreased. Turning the duct  180  degrees in the plenum wall hole to its position shown in FIG. 4 where the elliptical opening  70  of the beveled edge faces away from the flow of gas will negate the ramming effect of the flow of gas on the exposed opening  70  and will decrease the flow of gas through the duct passageway.  
         [0039]    In addition to adjusting the flow of gas through the duct  48  by rotating the duct in the hole  46  of the plenum first wall  40 , moving each regulator duct  48  axially so that its second end  54  is spaced further away from the second wall  42  of the plenum will increase the area between the duct second end  54  and the plenum second wall  42  and enhance the free flow of gas supplied through the second volume  38  of the plenum to the duct and through the duct passageway into the first volume  26  of the test chamber. Conversely, moving each duct  48  axially through the plenum first wall holes  46  toward the plenum second wall  42  so that the duct second end  54  is positioned closer to the plenum second wall  42  decreases the area between the duct second end  54  and the plenum second wall  42  and restricts the free flow of gas supplied through the second volume  38  of the plenum to the duct and through the duct passageway into the test chamber interior volume  26 . Thus, by rotating each duct  48  in its hole  46  of the first walls  40  of the plenum sections and by axially adjusting the position of each duct  48  in its hole  46  in the plenum first walls, the rate of gas flow through each duct passageway from the second volume  38  of the plenum to the first volume  26  of the test chamber can be adjusted. When the desired rate of gas flow through each duct passageway is achieved, the duct  48  can be held in its adjusted position by tightening the screw  88  of the locking mechanism  50 , thereby holding the duct stationary in its adjusted position relative to the plenum first wall  40 .  
         [0040]    By providing a plurality of holes  46  in the plenum first walls  40  on the opposite sides of the test chamber interior volume  26  and a plurality of gas regulators  12  mounted in the holes, the flow of gas from the plenum interior volume  38  into different portions of the test chamber interior volume  26  can be adjusted, thereby achieving a means of obtaining a more spatially uniform rate of temperature range throughout various test specimens or throughout various portions of a test specimen positioned in the interior volume of the test chamber.  
         [0041]    While the present invention has been described by reference to a specific embodiment, it should be understood that modifications and variations of the invention may be constructed without departing form the scope of the invention defined in the following claims. For example, each of the flow regulator ducts could be mounted stationary in the plenum wall and be provided with a beveled second end that is mounted on the duct for relative rotational and axial movement of the second end relative to the stationary duct, the gas regulator ducts could be mounted in a tight friction fit in the plenum wall holes without the need for a locking mechanism, and the flow regulator ducts could be provided with flexible hoses similar to those employed in the prior art directing the flow of gas from the regulators to a particular location in the test chamber interior.