Abstract:
A fluid check valve for use in an aircraft fluid handling system having a confined surrounding structure where a first distance is defined between a fluid duct and the surrounding structure where the design of the fluid check valve is configured to facilitate removal of a first flange and the flow duct by moving the first flange and flow duct a second distance that is less than the first distance. The check valve is offset into the upstream side of a second flange to provide the reduction in the distance that the first flange has to be displaced to remove the first flange and flow duct from the check valve. A first alternate configuration of the fluid check valve utilizes rotational stops attached to the downstream surface of the flow flaps and in a second alternate embodiment configuration, rotational stops extend upstream from the flow flaps and make contact with at least one tower structure to limit the flow flap rotation in the open position.

Description:
PRIORITY 
       [0001]    This application claims the priority of Provisional Patent Application Ser. No. U.S. 61/221,961 filed on Jun. 30, 2009. 
     
    
     TECHNICAL ORIENTATION 
       [0002]    This low clearance fluid check valve relates to a fluid valve assembly for use in an aircraft fluid transport system having limited structural clearance where the associated ducting must be removed to service the check valve. The structure of the fluid check valve is such that at least one fluid duct can be attached or removed with a reduced amount of clearance. 
       BACKGROUND 
       [0003]    It is known to place a flap type check valve in the flow stream of a fluid to prevent fluid from flowing in a direction that is opposite to that desired. This type of valve is widely used in such applications as home sump pumps and in industrial chemical plants and in aircraft ground fuel handling equipment. However, in these applications, space is not at a premium and the removal of the fluid duct work that is joined to the check valve assembly is not hindered by the location of other components or surrounding structure. In other applications, the surrounding structure can hinder the removal of the inlet and/or outlet fluid ducts. A good illustration of this type of application is aircraft fluid systems where the back flow of engine generated bleed air cannot be tolerated and where surrounding aircraft structure can be confining for the assembly and disassembly of fluid ducting. In these applications it would be desirable to incorporate a fluid check valve that exhibits a low clearance profile in at least one side of the check valve to allow for the removal of the associated fluid duct with a minimal amount of displacement of the duct away from the check valve. This required amount of displacement would allow the duct to be removed with clearance from the surrounding structure unlike prior art check valves which require that other aircraft systems and structure be disassembled to yield the required amount of displacement clearance to allow for removal of the fluid duct. 
       SUMMARY 
       [0004]    The present low clearance fluid check valve is particularly well suited for use in an aircraft environment since it has a unique structure and function that facilitates the removal and servicing of the check valve through removal of a mating fluid duct. The prior art aircraft fluid check valve requires a much greater clearance to remove one of the fluid ducts to service the check valve. Disclosed is an aircraft check valve having a low clearance required to service the check valve. A number of alternate embodiments are also disclosed which reduce the distance that the mating fluid duct has to be lifted or displaced from the check valve to allow for removal of the fluid duct from the aircraft or other system. In a first embodiment, the positioning of the valve has been moved relative to the duct flange mating line in a direction opposite to the duct that is to be removed. In this version, a tower is used as a travel stop for the check valve opening and closing flaps. This provides for reduction of the displacement that the fluid duct has to be displaced (moved) to allow for it to be laterally moved and removed from the aircraft. 
         [0005]    In a second embodiment, a plurality of rotation stops that are attached to opening and closing flaps of the check valve are located on the downstream side of the flaps. These stops are much lower in profile that the tower style of stop. This configuration provides for a lower clearance height and the fluid duct can be moved away from the check valve assembly a reduced distance prior to removing it from the check valve. 
         [0006]    In a third embodiment, the rotation stops for limiting the rotation of the flaps have been formed by extending the flaps at an angle away from the flap towards the upstream flow. When the flaps are fully opened, the stops contact a tower that is formed on the upstream side of the check valve. This results in a very low profile on the downstream side and the downstream duct only has to be lifted away from the check valve a short distance before it can be laterally shifted and removed from the check valve assembly as part of the aircraft fluid ducting system. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1  is a cross-sectional view of a prior art fluid check valve assembly installed in an aircraft; 
           [0008]      FIG. 2  is a cross-sectional view of the exemplary fluid check valve assembly installed in an aircraft; 
           [0009]      FIG. 3  is a cross-sectional view of the exemplary fluid check valve assembly with the check valve flaps in an open position. 
           [0010]      FIG. 4  is a planar top view of the exemplary fluid check valve assembly shown in  FIG. 3 . 
           [0011]      FIG. 5  is a cross-sectional view of a first alternate embodiment of the exemplary fluid check valve; 
           [0012]      FIG. 6  is a cross-sectional view of a second alternate embodiment of the exemplary fluid check valve. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    Referring now to the discussion that follows and also to the drawings, illustrative approaches to the disclosed systems and methods are shown in detail. Although the drawings represent some possible approaches, the drawings are not necessarily to scale and certain features may be exaggerated, removed, or partially sectioned to better illustrate and explain the present disclosure. Further, the descriptions set forth herein are not intended to be exhaustive or otherwise limit or restrict the claims to the precise forms and configurations shown in the drawings and disclosed in the following detailed description. 
         [0014]    Moreover, a number of constants may be introduced in the discussion that follows. In some cases illustrative values of the constants are provided. In other cases, no specific values are given. The values of the constants will depend on characteristics of the associated hardware and the interrelationship of such characteristics with one another as well as environmental conditions and the operational conditions associated with the disclosed system. 
         [0015]    Now referring to  FIG. 1  of the drawings, a cross-sectional view of a prior art fluid check valve  2  assembly is shown. The prior art check valve  2  assembly is shown installed in an aircraft having a structure wall which is distance H 1  from a fluid duct  11 . The fluid duct  11  is attached to a duct flange  20  which is held against a check valve flange  13 , which extends from the check valve  2 , by a band clamp  40 . To allow for removal of the check valve  2  the distance that the duct flange  20  must be displaced upward away from the check valve flanges  20 ,  25  interface is a distance labeled as H 2 . Note that in this installation, the distance H 2  exceeds the distance H 1 . Thus, the check valve  2  cannot be removed for servicing or replacement unless the structure wall is moved away from the fluid duct  11  or the fluid system containing the prior art fluid check valve  2  assembly is removed from the aircraft. Reducing the distance H 2  that is required to remove the duct  11  and first duct flange  20  from the aircraft to a value less that the distance H 2  would facilitate removal of the prior art check valve  2  assembly without the complication of removing the prior art fluid check valve  2  assembly from the aircraft or moving the structure wall. Such a fluid check valve assembly is shown in the subsequent Figures. 
         [0016]    The check valve flange  13  is clamped between the first duct flange  20  and the second flange  25  and held together using band clamp  40 . Seals  21  and  26  positioned on either side of the check valve flange  13  function to prevent fluid from leaking past the first duct flange  20  and second flange  25 . 
         [0017]    To locate the first duct flange  20  in position on the check valve flange is an annular ridge  27  which contacts the outer edge of the check valve flange  13 . The second flange  25  is located relative to the check valve  2  and check valve flange  13  using an inner annular ridge  22  and an outer annular ridge  23 . The inner annular ridge  22  contacts a check valve flange lip  18  and the outer annular ridge  23  contacts the same check valve flange lip  18  on an opposite side thereby holding and centering the check valve  15  relative to the second duct flange  25 . 
         [0018]    Towers  12 A and  12 B operate to act as a stop to the opening movement of the flow flaps  30 A and  30 B. This is more clearly illustrated with reference to  FIG. 4 . Both the first flow flap  30 A and the second flow flap  30 B rotate on a shaft  14  and open when the flow of fluid is in flow direction  31  and then close when the flow of fluid is in an opposite direction. The check valve  2  is shown in a closed position in  FIG. 1 . 
         [0019]    First flap  30 A and the second flow flap  30 B seal at their outer surfaces against first layer  32  which supported by second and third layers  33  and  34  respectively. Note that the position of the tops of the towers  12 A and  12 B to a large extent determines the distance that the first duct flange  20  and fluid duct  11  must be moved upward to allow for removal of the fluid duct  11  along with the first duct flange  20  to allow for removal of the check valve  2  for servicing or replacement. 
         [0020]    Now referring to  FIG. 2  of the drawings, a cross-sectional view of the exemplary fluid check valve assembly  10  is shown as installed in an aircraft or other similar application. A fluid duct  11  is shown as attached to the check valve  15  with a first duct flange  20 . The fluid duct  11  is attached to the first duct flange  20  and extends to within a distance H 1  of the structure wall  3 . Attached to a second duct flange  25  is another fluid duct (not shown). 
         [0021]    The check valve  15  includes a mounting extension flange  37  where the mounting extension flange  37  includes a check valve flange  13 . The check valve flange  13  is clamped between the first duct flange  20  and the second flange  25  and held together using band clamp  40 . Seals  21  and  26  positioned on either side of the check valve flange  13  function to prevent fluid from leaking past the first duct flange  20  and second flange  25 . 
         [0022]    To locate the first duct flange  20  in position on the check valve flange is a annular ridge  27  which contacts the outer edge of the check valve flange  13 . The second flange  25  is located relative to the check valve  15  and check valve flange  13  using an inner annular ridge  22  and an outer annular ridge  23 . The inner annular ridge  22  contacts a check valve flange lip  18  and the outer annular ridge  23  contacts the same check valve flange lip  18  on an opposite side thereby holding and centering the check valve  15  relative to the second duct flange  25 . The check valve  15  is spaced away from the fluid duct  11  using the mounting extension flange  37 . By moving the check valve  15  downward, the vertical distance that the fluid duct  11  and first duct flange  20  must be moved upward (labeled as H 2 ) is significantly reduced as compared to the prior art check valve assembly  2 . Since the distance H 2  is less than H 1 , the duct  11  and the attached first duct flange  20  can be removed allowing removal of the check valve  15  without moving the structure wall  3  or removing the whole fluid check valve assembly  10  and other fluid control system structure. 
         [0023]    Towers  12 A and  12 B operate to act as a stop to the opening movement of the flow flaps  30 A and  30 B. This is more clearly illustrated with reference to  FIG. 4 . Both the first flow flap  30 A and the second flow flap  30 B rotate on a shaft  14  and open when the flow of fluid is in flow direction  31  and then close when the flow of fluid is in an opposite direction. The check valve  15  is shown in a closed position in  FIG. 2 . 
         [0024]    First flap  30 A and the second flow flap  30 B seal at their outer surfaces against first layer  32  which supported by second and third layers  33  and  34  respectively. Note that the position of the tops of the towers  12 A and  12 B to a large extent determines the distance that the first duct flange  20  and duct  11  must be moved upward to allow for removal of the fluid duct along with the first duct flange  20  to allow for removal of the check valve  15  for servicing or replacement. 
         [0025]    Now referring to  FIG. 3  of the drawings, a cross-sectional view of the fluid check valve assembly  10  of  FIG. 2  is shown with the flow flaps  30 A and  30 B shown in an open position. The towers  12 A and  12 B act to stop the opening angle of the flow flaps  30 A and  30 B which rotate on bearings  38 A,  38 B,  38 C and  38 D respectively which are rotatably supported on shaft  14 . Shaft  14  passes through bearings  38 A,  38 B,  38 C,  38 D and then into the mounting extension flange  37  for support. The first flow flap  30 A is supported on bearings  38 A and  38 B while, in a similar fashion, the second flow flap  30 B is rotatably supported on bearings  38 C and  38 D. 
         [0026]    The first duct flange  20  is commonly attached to an air duct or to a ring flange. An AS1895 type flange can be used for either the first and/or second duct flanges  20 ,  25 . The check valve flange  13  is trapped between the first duct flange  20  and the second flange  25  which are held together using a band clamp  40  or other suitable prior art fastening means. An inner annular ridge  22  formed in the second flange  25  locates the check valve flange  13  on the second flange  25  working in conjunction with an outer flange  23  to trap the check valve flange lip  18  formed as part of the check valve flange  13 . The first duct flange  20  is located on the check valve flange using the annular ridge  27  and is clamped to the second flange  25  using the band clamp  40 . 
         [0027]    Now referring to  FIG. 4  of the drawings, a top planar view of the exemplary fluid check valve assembly  10  of  FIG. 3  is shown in an open configuration. The check valve  15  has the check valve flange  13  extending radially to provide a platform for clamping between the first and second flanges  20  and  25 . Extending out of the planar surface of the drawing are the two towers  12 A and  12 B and act as stops to the rotation of the first and second flow flaps  30 A and  30 B as shown in  FIG. 4 . Hinges  38 A and  38 B provide rotational support to the first flow flap  30 A on the shaft  14 , while hinges  38 C and  38 D provide rotational support to the second flow flap  30 B on the shaft  14 . When the flow flaps  30 A and  30 B are in the open position shown, the flow opening  39  allows fluids to flow through the fluid check valve assembly  10 . 
         [0028]    Now referring to  FIG. 5 , a cross-sectional view of a first alternate embodiment of the exemplary fluid check valve assembly  50  is shown in a closed position. The check valve  46  is mounted to a first duct flange  20  and a second flange  25  using a check valve flange  64  which is attached to the support block  54  and to the support layers  62  and  66 . The check valve flange  64  extends to engage the first duct flange  20  and the second flange  25  and is clamped into position using a band clamp  40 . An inner annular ridge  22  formed on the second flange  25  and an equally spaced outer annular ridge  23  trap the check valve flange  64  and positions the check valve  46  relative to the second flange  25 . An annular ridge  27  formed on the first duct flange  20  acts to position the first duct flange  20  relative to the check valve  46 . 
         [0029]    The first and second flow flaps  52 A and  52 B are shown in a closed position where no flow opposite to the direction  31  is allowed. The first and second flow flaps are rotatably supported on shaft  14  where the shaft  14  is supported in support block  54  which is attached to the check valve flange  64 . A first rotation stop  56 A is attached to the first flow flap  52 A and a second rotation stop  56 B is attached to the second flow flap  52 B. When the first and second flow flaps  52 A,  52 B are forced to an open position by the fluid flow, as shown by the motion direction arrows  58 ,  60 , the first and second rotation stops  56 A,  56 B contact one another and thereby prevent the first and second flow flaps  52 A,  52 B from rotating any further than the pre-selected opening range. 
         [0030]    Now referring to  FIG. 6  of the drawings, a cross-sectional view of a second alternate embodiment of the exemplary fluid check valve assembly  80  is shown with the check valve  90  in a closed position such that any fluid flow in a direction opposite to the direction arrow  31  is blocked. The check valve  90  includes a check valve flange  88  which radially extends from the check valve  90  and is clamped between a first duct flange  20  and a second flange  25  using a band clamp  40  or any other suitable retaining device. The first flow flap  82 A rotates about shaft  14  and is attached to a leg rotation stop  84 A which extends outward at an angle from the flap hinges  38 A,  38 B (see  FIG. 4 ). As the first flow flap  82 A rotates to the open position, the first leg rotation stop  84 A moves in the direction  60 . The second flow flap  82 B rotates about shaft  14  and is attached to a rotation stop  84 B which extends outward at an angle form the flap hinges  38 C,  38 D (see  FIG. 4 ). As the second flow flap  82 B rotates to the open position, the second rotation stop  84 B moves in the direction  58 . At least one stop tower  12  extends downward form the check valve flange  88  and supports the shaft  14  and stops the flow flaps  82 A and  82 B from over rotating by contacting the first and second leg rotation stops ( 84 A,  84 B). 
         [0031]    The check valve  90  is mounted to a first duct flange  20  and a second flange  25  using a check valve flange  88  which is attached to the support block  92  and to the supports  86  and  89 . The check valve flange  88  extends to engage the first duct flange  20  and the second flange  25  and is clamped into position using a band clamp  40 . An inner annular ridge  22  formed on the second flange  25  and an equally spaced outer annular ridge  23  trap the check valve flange  88  and positions the check valve  90  relative to the second flange  25 . An annular ridge  27  formed on the first duct flange  20  acts to position the first duct flange  20  relative to the check valve  90 . 
         [0032]    The present disclosure has been particularly shown and described with reference to the foregoing illustrations, which are merely illustrative of the best modes for carrying out the disclosure. It should be understood by those skilled in the art that various alternatives to the illustrations of the disclosure described herein may be employed in practicing the disclosure without departing from the spirit and scope of the disclosure as defined in the following claims. It is intended that the following claims define the scope of the disclosure and that the method and apparatus within the scope of these claims and their equivalents be covered thereby. This description of the disclosure should be understood to include all novel and non-obvious combinations of elements described herein, and claims may be presented in this or a later application to any novel and non-obvious combination of these elements. Moreover, the foregoing illustrations are illustrative, and no single feature or element is essential to all possible combinations that may be claimed in this or a later application.