Abstract:
The present disclosure relates to a rotary check valve, which utilises the rotation of a rotary element to open and close the valve, rather than pivoting of hinge flappers, such as in other check valve designs. The rotary element is rotatably mounted to a valve plate which features shrouded openings that define windows. A plurality of vanes extending from the rotary element are used to close or open the windows in response to a reverse or forward fluid flow, respectively. This action opens or closes the valve. This design may reduce the force exerted on the valve components when the valve opens and closes, when compared to a pivoting hinge flapper design.

Description:
FOREIGN PRIORITY 
       [0001]    This application claims priority to European Patent Application No. 16461521.3 filed 10 May 2016, the entire contents of which is incorporated herein by reference. 
       TECHNICAL FIELD 
       [0002]    The present disclosure relates to check valves. 
       BACKGROUND 
       [0003]    It is known to use check valves to allow fluid flow in one direction therethrough, and to prevent flow in the opposite direction. Check valves are widely used in a wide variety of applications, for example in air conditioning systems, for example in aircraft air conditioning systems. 
         [0004]    One form of check valve includes a pair of hinged flappers that pivot open in the direction of fluid flow when the fluid pressure differential exceeds a predetermined valve “cracking pressure”. If a negative pressure differential exists across the valve, the flapper elements close, preventing flow reversal. 
         [0005]    Such check valves typically include a pair of flapper elements and frequently employ stops or bumpers which restrict the opening movement of the flapper element past a predetermined maximum opening angle. Such a check valve is disclosed in, for example, GB 2514953. 
         [0006]    When the cracking pressure is exceeded the flapper elements may open at high speed. When they subsequently cooperate with the stops/bumpers high stresses may be generated. This may lead to reduced part life and increased maintenance costs. 
       SUMMARY 
       [0007]    Disclosed herein is a check valve. The check valve comprises a valve plate comprising a plurality of openings therethrough and a shroud extending from the valve plate around each of the openings. The shroud and the valve plate define an at least partially circumferentially facing window. The check valve also comprises a rotary element rotatably mounted to the valve plate about a rotational axis. The rotary element comprises a plurality of radially extending vanes and is mounted such that each vane is positioned between two adjacent shrouds. The vanes are angled such that fluid flow incident thereon in a direction parallel to said rotational axis will rotate the rotary element about the rotational axis. The rotary element is rotatable between an open position in which the vanes are spaced circumferentially from the windows to allow fluid to flow through the windows via the openings, and a closed position in which the vanes close the windows, thereby preventing fluid flow therethrough. 
         [0008]    In an embodiment of the above check valve, a lower portion of the window is defined by a lip upstanding from the valve plate. Additionally, the lip may have a profile complementary to that of the vane to create an area contact therebetween. 
         [0009]    In a further embodiment of any of the above check valves, the vanes engage around the respective edges of the windows to close the windows. Additionally, a sealing element may be provided around the edges of each window, and the sealing element may be resilient. 
         [0010]    In a further embodiment of any of the above check valves, each shroud comprises a bumper surface configured to contact a respective vane along a length thereof in the open position. Additionally, the bumper surface may have a profile complementary to that of the vane to create an area contact therebetween. Further additionally or alternatively, the bumper surface may comprise a separate bumper element. 
         [0011]    In a further embodiment of any of the above check valves, the vanes rotate about the rotational axis between the closed and open valve positions through an angle of between 10° and 20°, more narrowly 14° to 18°, for example, 16°. 
         [0012]    In a further embodiment of any of the above check valves, the valve plate comprises between 10 and 16 openings and the rotary element comprises the same number of vanes. 
         [0013]    In a further embodiment of any of the above check valves, the valve plate comprises 12 openings and the rotary element comprises 12 vanes. 
         [0014]    In a further embodiment of any of the above check valves, the vanes have an airfoil cross-section. 
         [0015]    In a further embodiment of any of the above check valves, the vanes feature a twist along their radial axis. 
         [0016]    In a further embodiment of any of the above check valves, the rotary element is rotatably mounted onto a shaft extending from the valve plate. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    Some exemplary embodiments of the present disclosure will now be described by way of example only, and with reference to the following drawings in which: 
           [0018]      FIG. 1  shows a perspective view of an embodiment of a check valve in accordance with this disclosure, in an intermediate position between an open position and a closed position; 
           [0019]      FIG. 2  shows a side elevation of the check valve of  FIG. 1 ; 
           [0020]      FIG. 3  shows a perspective view of the check valve of  FIG. 1  in an open position; 
           [0021]      FIG. 4  shows a perspective view of the check valve of  FIG. 1  in a closed position; 
           [0022]      FIG. 5  shows a perspective view of the valve plate of the check valve of  FIG. 1 ; 
           [0023]      FIG. 6  shows a perspective view of the rotary element of the check valve of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0024]    With reference to  FIGS. 1 to 4 , a check valve  2  is illustrated. Check valve  2  is configured to be mounted around its periphery in or to, for example, a duct in order to prevent reverse flow of a fluid through the duct. As shown, the check valve  2  comprises a static, generally circular valve plate  10  and a rotary element  20 , which is rotatably mounted to the valve plate  10  about rotational axis R. Although circular in this embodiment, the valve plate  10  may be of any shape. 
         [0025]    As can be seen more clearly in  FIGS. 5 and 6 , valve plate  10  comprises a shaft  15  that extends along rotational axis R and rotary element  20  comprises a bore  25  through the central hub  24  that fits over shaft  15  to allow rotary element  20  to be mounted rotatably to valve plate  10 . A bearing (not shown) may be mounted around the shaft  15  and the bore  25  to allow rotation of the rotary element  20  around the shaft  15 . Alternatively, any other suitable means of providing rotatable mounting of the rotary element  20  to the valve plate  10  as would be understood by one skilled in the art, may be used within the scope of this disclosure. 
         [0026]    The valve plate  10  comprises a plurality of openings  13  therethrough. In this case, the openings  13  are generally triangular or trapezoidal in shape, however, any shape opening may be used within the scope of this disclosure. 
         [0027]    The valve plate  10  also comprises shrouds  12  that extend upwardly from the valve plate  10  and around each opening  13 . The shrouds  12  and the valve plate  10  define windows  14 . Windows  14  face in at least partially a circumferential direction. As can be seen more clearly in  FIGS. 2 and 5 , shrouds  12  are shaped such that portions of the windows  14  face in radial and axial (i.e. in the direction of the rotational axis R) directions, in addition to the circumferential direction. However, in alternative embodiments, the windows  14  may only face the circumferential direction. 
         [0028]    A lower portion of each window  14  adjacent the surface of the valve plate  10  is defined by a lip  16  upstanding from the valve plate  10 . However, in alternative embodiments, valve plate  10  does not comprise such lips  16 . The function of the lips  16  is described below in relation to the closing of the check valve  2 . 
         [0029]    In the depicted embodiment, the edges of windows  14  comprise a sealing element  19  thereon, which aids closing of the check valve  2  (as described in more detail below). Sealing element  19  may be a resilient and/or compliant material. In alternative embodiments, however, the edges of windows  14  do not comprise an additional sealing element  19 . 
         [0030]    Bumper surfaces  18  are formed on or associated with a rear surface  17  of shrouds  12 . Bumper surfaces  18  are configured to contact a respective vane  22  along a length thereof, as will be described in more detail below in relation to the opening of the check valve  2 . As shown in  FIGS. 1 to 5 , the rear surface  17  of shrouds  12  at least partially faces the circumferential direction (i.e. the rear surfaces  17  are the back surfaces on the body of the shrouds  12 , opposite the windows  14 ). In the depicted embodiment, the bumper surface  18  comprises a separate bumper element attached to the rear surface of the shroud  12 , however, in alternative embodiments, bumper surface  18  is just a specific area of the rear surface  17  of the shroud  12  that contacts a length of vanes  22  in the open position. 
         [0031]    The rotary element  20  has a plurality of vanes  22  that extend radially from a central hub  24 . The vanes  22  extend across the valve plate  10 , in between adjacent shrouds  12 , and have a leading edge  26  that faces the valve plate  10  surface and is separated by a small gap therefrom. In alternative embodiments, the leading edge  26  may be in loose contact with the valve plate  10 , as discussed in more detail below. 
         [0032]    There are the same number of vanes  22  as windows  14  (and also shrouds  12  and openings  13 ). The vanes  22  are angled relative to the rotational axis R, such that when fluid flow is incident on the vanes  22  in a direction parallel to the rotational axis R the rotary element  20  is forced to rotate. 
         [0033]    The check valve  2  has a forward side and a backward side. The backward side is the side of the check valve  2  into which shrouds  12  extend, whereas the forward side is the opposite side to the backward side. When in use, the check valve  2  can encounter fluid flow in a positive (i.e. forward) flow direction or a negative (i.e. reverse) direction. In the positive flow direction, fluid passes from the forward side to backward side, through the openings  13  and windows  14 , whereas in the negative flow direction, fluid attempts to pass from the backward side to the forward side through the windows  14  and openings  13 . 
         [0034]    When there is a positive flow differential across the check valve  2 , fluid will flow in the positive flow direction and exit the valve  2  through windows  14 . The fluid will be directed onto vanes  22  causing the rotary element  20  to rotate into an open position, which permits further fluid flow through the valve  2 . As shown in  FIG. 3 , when fully open, a length of each vane  22  will be forced into contact with respective bumper surface  18 . Rotation to this position causes the vanes  22  to exert a force on the bumper surfaces  18 . The bumper surface  18  has a profile which is complementary to that of the vane  22  such that there is contact between them over an area rather than a line contact. 
         [0035]    When there is a negative flow differential across the check valve  2 , fluid will flow in the negative flow direction. In this case, fluid flow incident on vanes  22  will cause rotary element  20  to rotate each vane  22  into contact with windows  14  and lips  16 . This prevents fluid from flowing through the windows  14  to the forward side of the check valve  2 , placing the valve in a closed position, as shown in  FIG. 4 . Rotation to this position causes the vanes  22  to exert a force on the windows  14  and the lips  16 . 
         [0036]    In order to prevent fluid flow through the valve  2  in the closed position, the vanes  22  are sized and shaped to completely cover windows  14 . The windows  14  and lips  16  are also contoured to complement the shape and profile of the vanes  22 . Sealing elements  19  also act to aid sealing between the vanes  22  and the windows  14 . 
         [0037]      FIGS. 1 to 4 and 6  show vanes  22  having an airfoil cross-section, however, it is to be understood that vanes  22  may also be planar or have any other suitable cross-section, as would be apparent to one skilled in the art. In addition, vanes  22  may also comprise other characteristics such as a twist along their length (i.e. along their radial axis). 
         [0038]    As will be understood by one skilled in the art, varying the vane  22  cross-section and characteristics may be used to tailor the force required to rotate the rotary element  20  to provide a certain cracking pressure (i.e. minimum force necessary for the valve  2  to rotate from a closed to an open position) or to change the valve&#39;s response time between opening and closing. It may also be used to tailor the amount of force that the vanes  22  exert on the windows  14 , lips  16 , sealing elements  19  and bumper surfaces  18 , during opening and closing of the valve. 
         [0039]    In embodiments not depicted, but within the scope of this disclosure, a biasing element may be used to bias the check valve  2  to a closed position. The biasing member may also be used to increase the cracking pressure of the check valve  2 . The biasing member could be a spring attached between the shrouds  12  and the vanes  22 , a spring attached between the hub  24  and shaft  15  or another means that inhibits the rotation of the rotary element  20  from the closed position to the open position. 
         [0040]    In the depicted embodiment, the leading edge  26  is positioned above the valve plate  10  surface. In this way, the leading edge  26  and valve plate  10  do not contact each other as the vanes  22  rotate over the valve plate  10 , minimising friction therebetween. However, in alternative embodiments, the leading edge  26  is in loose contact with the valve plate  10  surface. This aims to minimise fluid leakage between the leading edge  26  and the valve plate  10 , without generating unacceptable friction or wear. 
         [0041]    There are twelve openings  13  (and corresponding numbers of vanes  22  and shrouds  12 ) shown, however, it should be understood that only two or more openings (and corresponding numbers of vanes  22  and shrouds  12 ) are necessary for the check valve  2  to operate. It is believed that fewer openings  13  may increase the pressure drop across the check valve  2 . However, as explained below, fewer openings  13  also increases the impact forces exerted by the vanes  22  on the windows  14 , lips  16 , sealing elements  19  and bumper surfaces  18 . As will be understood by one skilled in the art, this trade-off can be used to tailor the number of openings  13  to the given application of the check valve  2 . In certain embodiments, a suitable number of openings  13  is between  10  and  18 . 
         [0042]    The openings  13  and windows  14  are sized to allow sufficient fluid flow therethrough for the application at hand. The openings  13  and windows  14  may therefore be sized to have an area that is any percentage of the total valve plate  10  area, as a given application requires. 
         [0043]    The size/number of openings  13 , their spacing and subsequent number of vanes  22  dictates how much angular rotation rotary element  20  may undergo about rotational axis R between the open and closed positions. A lower angular rotation angle a decreases the impact forces exerted by the vanes  22  on the windows  14 , lips  16  and bumper surfaces  18  when the valve  2  rotates to the closed and open positions. Thus, the number, size and spacing of the openings and the corresponding number of vanes  22  can be varied to reduce or increase the impact force as desired. In certain embodiments, a suitable angle of angular rotation is in the range 10°≦α≦20°, particularly, 14°≦α≦18°, and more particularly α=16°. However, any angular rotation angle between 0°&lt;α&lt;180° can be used, within the scope of this disclosure. 
         [0044]    The reduction of the impact force provided by the combination of the openings  13  and vanes  22  and any of their characteristics (as described above) may improve the life of the check valve  2 . 
         [0045]    The relatively large size of the windows  14  spreads the impact force over a larger area relative to other check valves designs, which acts to reduce the stress caused thereby. Lips  16  and sealing elements  19  may also act as areas of reinforcement for windows  14 , which aids the absorption of stress exerted on the windows  14 . Bumper surfaces  18  may also act to reinforce the shrouds  12  and protect them from the force exerted on them by the vanes  22  rotating to the open position. 
         [0046]    The various materials and manufacturing process that may be used to produce the check valve  2  will now be described. 
         [0047]    The valve plate  10  and rotary element  20  may be made of a metallic material, a plastic material or a composite material, as a given application or working environment requires. For instance, they may be made of aluminum, titanium, steel or an alloy thereof. They may alternatively be made of an Ni-based alloy. Depending on the application of the check valve  2 , they may be corrosion resistant or have a corrosion resistant coating applied thereto. In addition or alternatively, they may also have a heat resistant coating applied thereto. 
         [0048]    The valve plate  10  and rotary element  20  may be additively manufactured or subtractively manufactured (e.g. machined). Alternatively, they may be cast. The shrouds  12  and shaft  15  may be integrally formed as part of the valve plate  10  or may be produced as separate components and coupled thereto. The vanes  22  may be integrally formed as part of the rotary element  20 , or may be separate components coupled thereto. 
         [0049]    Lips  16 , sealing elements  19  and bumper surfaces  18  may be separate components from the valve plate  10  and coupled thereto, or alternatively, may be integrally formed as part of the valve plate  10 . The lips  16 , sealing elements  19  and bumpers  18  may be made of the same material as the valve plate  10 , or a different material. Lips  16 , sealing elements  19  and bumpers  18  may be made of a more compliant material than valve plate  10 , such as a rubberised material, to better absorb impact forces or provide improved sealing. Alternatively, the lips  16 , sealing elements  19  and bumpers  18  may have undergone a hardening treatment to make them more resilient to impact forces. 
         [0050]    Although the figures and the accompanying description describe particular embodiments and examples, it is to be understood that the scope of this disclosure is not to be limited to such specific embodiments, and is, instead, to be determined by the following claims.