Abstract:
An exemplary embodiment disclosed herein relates to an articulatable sealing device. The device includes a plurality of seal elements each of which is urgable against a seal-surface, a fixing member tightenable about a perimeter of the seal elements, and a retractor in operable communication with the plurality of seal elements and able to move the plurality of seal elements in a desired direction.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. application Ser. No. 11/582,233, entitled “INTERMITTENT SEALING DEVICE AND METHOD” filed on Oct. 17, 2006, which is herein incorporated by reference in its entirety. Application Ser. No. 11/582,233 claims priority under 35 U.S.C. §119(e) to U.S. Provisional Application Ser. No. 60/728,991, entitled “CONFIGURATION FOR ADAPTABLE SEALS FOR REGENERATIVE HEAT EXCHANGERS (REGENERATORS)” filed on Oct. 21, 2005, which is herein incorporated by reference in its entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    Seal arrangements between two members, which are in movement relative to each other, are known in the arts. But at high temperatures, above 500° C. for example, and applications where the leakage across the seal has to be minimal, of the order of 0.1% to 3.0%, over an extended lifecycle many of the conventional sealing mechanisms cannot comply with these requirements. One example of such an application is a regenerative heat exchanger (regenerator) in which a porous disk or drum is first rotated into a hot fluid flow and second into a cold fluid flow to thereby transfer heat from the hot fluid to the cold fluid. To minimize the wear of the seals in contact with the moving regenerator disk a discontinuous moving regenerator disk, with lifting seals, has been used. A description of such a regenerator can be found in U.S. Pat. No. RE37134 to David Gordon Wilson, which is included as a reference in its entirety herein. In some regenerator applications the mixing of the cold and the hot fluid is troublesome and should, therefore, be minimized. Such a mixing of hot and cold fluids results from leakage by the seals between the two fluids. In applications using lifting seals in discontinuous regenerators, the leakage, though low, may still be greater than desired due to distortions in the seal-surface. Such distortions may hold the lifting seals far enough from the seal-surface to permit unacceptable levels of leakage to occur. Accordingly, improvements in sealing in the presence of such seal-surface distortions would be desirable in the art. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0003]    An exemplary embodiment disclosed herein relates to an articulatable sealing device. The device includes a plurality of seal elements each of which is urgable against a seal-surface, a fixing member tightenable about a perimeter of the seal elements, and a retractor in operable communication with the plurality of seal elements and able to move the plurality of seal elements in a desired direction. 
         [0004]    Further disclosed herein relates to an articulatable sealing device. The device includes, a plurality of seal elements, and a fixing member for intermittently fixing the seal elements to one another. The device further includes a retractor for intermittently retracting the seal elements from contact with a seal-surface, and at least one biasing member to urge each of the plurality of seal elements individually against a seal-surface. 
         [0005]    Further disclosed herein is an exemplary embodiment of a method of intermittently sealing to a surface. The method includes, independently urging at least one of a plurality of seal elements toward a seal-surface, intermittently clamping the plurality of seal elements to one another, and intermittently lifting the clamped plurality of seal elements away from the seal-surface. The method further includes intermittently releasing the clamp to thereby allow the seal elements to independently move toward and seal against a seal-surface. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike: 
           [0007]      FIG. 1  depicts a perspective view of a regenerator disclosed herein; 
           [0008]      FIG. 2  depicts a plan view of a matrix disclosed herein; 
           [0009]      FIG. 3  depicts a plan view of a matrix, a plurality of seal elements and a fixing member disclosed herein; 
           [0010]      FIGS. 4A-4D  depict perspective views of various stages of actuation of a sealing device disclosed herein; 
           [0011]      FIG. 5  depicts a cross sectional view of the regenerator shown in  FIG. 1 ; and 
           [0012]      FIG. 6  depicts an exploded perspective view of the sealing device shown in  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0013]    A detailed description of embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures. 
         [0014]    Referring to  FIG. 1  an embodiment of the invention will now be had with reference to a discontinuous regenerator shown generally at  10 . The regenerator  10  includes a rotatable porous matrix  14 , a fluid-carrying duct  18  and an actuatable seal device  22 . The heat exchanger  10  is shown with a single duct  18  and seal device  22  employed; however, it should be understood that more than one duct  18  and seal device  22  may be employed on either or both sides of the matrix  14  while still remaining within the spirit and scope of the present invention. 
         [0015]    The porous matrix  14  of the regenerator  10  has a seal-surface  24  thereon and a plurality of discrete flow compartments  26 ; four such compartments are illustrated in  FIG. 1 . Surrounding each flow compartment  26  is a seal line  30 . Each seal line  30  defines a perimeter around one of the flow compartments  26  on the seal-surface  24 . The seal device  22  forms a seal against the seal-surface  24  at the seal line  30  when the seal device  22  is actuated to the seal position. The seal line  30  may be in the shape of a circle as shown in  FIG. 1  or may be other shapes such as triangular, for example, as is shown by a seal line  32  shown in  FIG. 2 . There are limitations on the shapes that the seal lines  30 ,  32  may take and these limitations are based on the construction of the seal device  22  that will be discussed in more detail now. 
         [0016]    Referring again to  FIG. 2 , the seal device  22  uses a plurality of seal elements  34  to form the seal against the seal line  30  on the seal-surface  24  as is shown in this partial cross sectional view of the seal elements  34 . In this embodiment each seal element  34  has a female radiused edge  38  and a male radiused edge  42  on a side opposite of the female radiused edge  38 . The male edge  42  of one seal element  34  engages with the female edge  38  of an adjacent seal element  34  to form a seal between adjacent seal elements  34  while allowing the adjacent seal elements  34  to move and slide axially relative to one another. The shape of each seal element  34 , in a seal device  22 , can be identical to all the other seal elements  34  in the seal device  22  if for example the seal line  30  is a circle. Alternatively, the seal elements  34  may have various shapes in order to form a non-circular shape, as is the case for the seal line  32 , for example. The number of seal elements  34  that are used by each seal device  22  can vary depending upon the particular application. The more seal elements  34  that are used for a given seal line  30 ,  32  the more the seal device  22  is able to seal against surfaces with imperfections as will be described below with reference to  FIGS. 4A-4D . 
         [0017]    Referring to  FIG. 3  a seal element fixing member illustrated herein as a clamp ring  46  surrounds the perimeter of the seal elements  34 . A clamp actuator  50  when actuated pulls the clamp ring  46  into tension around the seal elements  34 , thus putting all of the seal elements  34  that create the closed shape into a circumferentially compressive force with each other seal element  34  in the particular seal device  22 . The compressive force between adjacent seal elements  34  creates friction between adjacent seal elements  34  that causes the seal elements  34  to lift together as one assembly when they are lifted away from the matrix  14 . The compressive force between adjacent seal elements  34  also creates a seal between adjacent elements  34  thereby preventing leakage therebetween. The clamp actuator  50  that tightens the clamp ring  46  may be pneumatic, hydraulic, servomotor controlled or controlled by any other applicable actuation that is known. 
         [0018]    Referring to  FIGS. 4A-4D  various phases of the seal device  22  showing the clamping and releasing of the clamp ring  46  about the seal elements  34  and pulling and pushing of the seal elements  34  relative to the seal-surface  24  are shown in detail. In  FIG. 4A  the clamp ring  46  is in tension around the seal elements  34  and the seal elements  34  are sealed against the seal line  30  of the matrix  14 . The clamp ring  46  has the seal elements  34  locked together as an assembly and can therefore be lifted away from the matrix  14  in the direction of arrows  54 . With the seal elements  34  lifted away from the matrix  14  to form a clearance gap  56  as shown in  FIG. 4B  the matrix  14  is able to move, in direction of arrow  57  for example, relative to the seal elements  34  without causing wear of the seal elements  34 . Each of the seal elements  34  is individually biased, in the direction of arrows  60 , toward the matrix  14  such that upon release of the tension in the clamp ring  46  the biasing force urges the individual seal elements  34  to move toward and make contact with the matrix  14  as is shown in  FIG. 4C . By individually urging each of the seal elements  34  the seal device  22  can permit each seal element  34  to make contact with the matrix  14 . In so doing the largest gaps that will exist between the seal elements  34  and the matrix  14  will be smaller than if the seal elements  34  were not able to move independently of one another. This gap-size reduction of embodiments disclosed herein is especially effective in reducing gap sizes that occur when a distortion  58  exists on the surface of the matrix  14 . The use of multiple seal elements  34  allows a single seal element  62  to be axially displaced with respect to the other seal elements  34  due to a local distortion  58 , for example, and thereby to decrease the overall leakage that would result had the seal elements  34  not been allowed to move independently from the seal element  62  towards matrix  14 . Embodiments with a greater number of seal elements  34  for a specific size seal line  32  will have smaller gap sizes since fewer seal elements  34  will be held away from the seal-surface  24  by the distortion  58 . Once all the seal elements  34 ,  62  have moved toward and made contact with the matrix  14  the actuator  50  can actuate and apply tension to the clamp ring  46  to thereby lock the seal elements  34  together sealing them to one another and preventing movement of any individual seal element  34  in a direction away from the matrix  14 . 
         [0019]    Referring to  FIGS. 1 ,  5  and  6  a detailed description of the seal device  22  and the mechanisms to control the movements of the seal elements  34  will now be described. In addition to the clamp ring  46  a ring shaped seal guide  70 , which is attached to a guide flange  74 , also surrounds and provides guidance to the seal elements  34 . The seal guide  70  loosely surrounds the seal elements  34  to allow the seal elements  34  to move freely in an axial direction relative to the seal guide  70 . The seal elements  34  ride on an outer surface  78  of the duct  18  and are sealed to the surface  78  with packing  82 . The packing  82  is contained within a channel  86  formed circumferentially in the seal elements  34 . Insulation  90  lines the inside of the duct  18  to minimize heat transfer to the seal device  22 . For sealing between the duct  18  and the seal elements  34  known methods such as O-rings, for example, can be used if appropriate to the particular application. The seal guide  70  is stationary relative to the duct  18  and thus the seal elements  34  move relative to the seal guide  74 . 
         [0020]    The seal guide  74  can have a noncircular shape to control the shape of the seal elements  34  such that they form a noncircular seal shape such as would be required to seal against seal line  32  as shown in  FIG. 2 . The duct  18  may also have a noncircular shape to complement the shape of the seal guide  74 . There are limits to the shapes that the seal line  32  and consequently the seal device  22  can take, however, which are due to the possibility of the seal elements  34 ,  62  collapsing radially inwardly if the compressive force applied to the seal elements  34 ,  62  is allowed to buckle an interface between seal elements  34 ,  62  radially inwardly. It is therefore recommended to maintain a convex curvature around the full perimeter of the seal line  32  to prevent such a buckling from occurring. 
         [0021]    As described above the seal elements  34  move in both axial directions, specifically toward and away from the matrix  14 . Holes  94  and  98  through the guide flange  74  permit pull rods  104  and push-rods  108  respectively to extend therethrough to urge the motion of the seal elements in the two directions. The push-rods  108  are also slidably engaged in holes  118  in an actuation support plate  122  that is attached to the duct  18  further from the location where the seal guide  74  is fixed to the duct  18 . Each push-rod  108  has a push-rod biasing member depicted herein as a compression spring  126  compressed between the support plate  122  and a flange  130  on the push-rods  108 . Thus the compression spring  126  is always in compression and is thereby supplying an urging force to the seal element  34  to which it is engaged in a direction toward the matrix  14 . The push-rods  108  engage recesses  134  in the seal elements  34  to positively locate the push-rods  108  relative to the seal elements  34 . 
         [0022]    Each pull rod  104  is connected to a seal element retractor illustrated herein as an axial actuator  138  that when actuated pulls the pull rod  104  in a direction away from the matrix  14 . The axial actuator  138  may be pneumatic, hydraulic, servomotor controlled or controlled by any other applicable actuation that is known. A head  142  on each rod  104 , on the opposite end of the rod  104  than is connected to the actuator  138 , engages with a latch  146  fixed on the clamp ring  46 . Thus, when the actuator  138  is actuated the pull rod  104  pulls the clamp ring  46  in a direction away from the matrix  14 . Several pull rods  104  and actuators  138  can be positioned around the seal guide  74  and support plate  122  to evenly distribute the load of the rods  104  on the clamp ring  46  to thereby control the motion of the clamp ring  46  resulting from the forces applied thereto. Alternate embodiments could have the pull rods  104  engaged directly to one or more of the seal elements  34 . Since the seal elements  34  are secured to one another by the clamp ring  46  retracting the pull rods  104  with the actuator  138  would retract all of the seal elements  34  as well. 
         [0023]    Depending upon the particular application employing the regenerator  10  disclosed herein, the temperatures of the fluid being sealed could be very high. For example in a gas turbine engine the hot fluid temperatures may be high enough to damage the springs  126  and the actuators  138  if they are located near the seal-surface  24  during times when the seal elements  34  are at the gap  56  distance from the seal-surface  24 . To protect the springs  126  and the actuators  138 , therefore, it may be desirable to locate the springs  126  and the actuators  138  at specific distances from these high-temperature locations. The lengths of the pull rods  104  and the push-rods  108  may therefore be customized for each application, such that longer rods  104 ,  108  are used for applications with higher-temperature fluids, for example, to thereby protect the springs  126  and the actuators  138  from heat damage. In applications with high temperatures it may be advantageous to use seal elements  34  made from materials such as ceramic, for example, such that the seal elements  34  may withstand the high temperatures without sustaining damage. 
         [0024]    With the construction just described the push-rods  108  in response to the clamp actuator  50  releasing the tension in the clamp ring  46  are able to push the seal elements  34 , individually, into contact with the seal-surface  24  of the matrix  14 . Additionally, the pull rods  104  are able to pull all of the seal elements  34  simultaneously away from the seal-surface  24  of the matrix  14  in response to the clamp actuator  50  applying tension to the clamp ring  46 . After this action the seal elements  34  are no longer in contact with the matrix  14  allowing the matrix  14  to move without causing wear of the seal elements  34 . 
         [0025]    While the invention has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the claims.