Abstract:
The subject matter of this specification can be embodied in, among other things, a valve assembly that includes a valve body having a fluid inlet, fluid outlet, and a movable closure member adapted to block fluid flow from the inlet to the outlet through a housing. The housing has an opening adapted to receive an actuator assembly that includes a central stationary shaft having at least one stator vane. A rotating collar is disposed around the stator vane and a portion of the central stationary shaft. The rotating collar has a housing and at least one stop member disposed inwardly in a cavity of the rotating collar. The rotating collar has at least two actuation chambers defined by the inner wall of the cavity in the rotating collar, the stationary vane, and the stop member. The rotating collar is coupled to the movable valve closure member.

Description:
TECHNICAL FIELD 
       [0001]    This invention relates to a valve device and more particularly to a butterfly type valve that is actuated by a vane type actuator device moved by fluid under pressure. 
       BACKGROUND 
       [0002]    To maximize the efficiency turbine engines are being run close to extreme conditions. To prevent compressor stall or provide blade clearance control, a series of air valves are sometimes used. These valve assemblies generally consist of an actuator and valve, often as a single line replacement unit (LRU). Coupling between the actuator and the valve, however, can require a tradeoff between the sometimes conflicting requirements of efficient torque transfer, size, weight, manufacturing complexity, and tolerance of misalignments in the valve assemblies. 
         [0003]    Rotary hydraulic actuators of various forms are currently used in industrial mechanical power conversion applications. This industrial usage is common for applications where continuous inertial loading is desired without the need for load holding for long durations, e.g. hours, without the use of an external fluid power supply. Aircraft flight control applications generally implement loaded positional holding, for example, in a failure mitigation mode, using substantially only the blocked fluid column to hold position. 
       SUMMARY 
       [0004]    In general, this document describes a fluid-actuated butterfly valve. 
         [0005]    In a first aspect, a valve assembly includes a valve body including a fluid inlet and fluid outlet and movable closure member disposed in a housing, said closure member adapted to substantially block fluid flow from the inlet to the outlet; said housing further having an opening adapted to receive an actuator assembly. The actuator assembly includes a central stationary shaft disposed in the valve body, said shaft having at least one stator vane member affixed to the central stationary shaft. A rotating collar assembly is disposed around the stator vane member and a portion of the central stationary shaft. The rotating collar assembly has a housing adapted to be received in the valve body, and has at least one stop member disposed inwardly in an inner cavity of the rotating collar assembly. The stop member is adapted to contact the stator vane member when the rotary collar assembly is rotated around the central shaft assembly in a first direction and adapted to contact the vane member when the rotary collar assembly is rotated in the opposite direction. The rotating collar has at least two actuation chambers defined by a portion of the inner wall of the cavity in the rotating collar assembly, the stationary vane member, and the stop member. The rotating collar assembly is coupled to the movable valve closure member. 
         [0006]    Various embodiments can include some, all, or none of the following features. The movable closure member can be a butterfly closure disc configured to open to allow fluid flow from the valve inlet to the valve outlet and close to substantially block fluid flow from the inlet to the outlet. The valve assembly can include an inlet actuation fluid port and an outlet actuation fluid port, each of said fluid ports fluidly connected to each actuation chamber in the rotating chamber assembly. The valve assembly can include a vane seal disposed on the stationary vane member, said vane seal adapted to sealingly engage a portion of the inner wall of the cavity. The valve assembly can include a stop seal disposed on the rotating collar assembly, said stop seal adapted to sealingly engage a portion of the central stationary shaft. The valve assembly can include a position sensor adapted to provide information indicative of the rotational position of the movable valve closure member relative to the central stationary shaft. The central stationary shaft can have at least a pair of the stator vane members, and the rotating collar assembly can have at least two stop members. 
         [0007]    In a second aspect, a method for controlling fluid flow includes providing a flow body including a fluid inlet and fluid outlet, providing a central stationary shaft disposed in the flow body, said shaft having at least one stator vane member affixed to the central stationary shaft, providing a rotating collar assembly disposed around the stator vane member and a portion of the central stationary shaft. The rotating collar assembly has at least one stop member disposed inwardly in an inner cavity of the rotor ring assembly and includes a first side and a second side and adapted to contact the stator vane member when the rotor ring assembly is rotated around the central shaft assembly in a first direction and adapted to contact the stator vane member when the rotor ring assembly is rotated in the opposite direction. The rotor ring includes at least two actuation chambers defined by a portion of the inner wall of the cavity in the rotor ring assembly, the stationary vane member, and the stop member. The method also includes providing a rotor housing disposed in the flow body, said rotor housing adapted to substantially block fluid flow from the inlet to the outlet, wherein said rotor ring assembly is coupled to the rotor housing, providing a rotational fluid at a first pressure and contacting the first side of the stop member of the rotor ring assembly with the first rotational fluid, providing a rotational fluid at a second pressure less than the first pressure and contacting the second side of the stop member of the rotor ring assembly with the second rotational fluid, and rotating the rotor housing in a first direction of rotation. 
         [0008]    Various implementations can include some, all, or none of the following features. The method can also include increasing the second pressure and reducing the first pressure until the second pressure is greater than the first pressure, and rotating the rotor housing in an opposite direction to the first direction of rotation. The method can also include stopping the rotation of the rotor housing in the opposite direction by contacting the stop member with the stator vane member. Providing the central stationary shaft can include providing at least a pair of the stator vane members, and providing the rotating collar assembly includes providing at least two stop members. The central stationary shaft, the rotor ring, and the rotor housing can isolate the rotational fluid into a first opposing pair of chambers and a second opposing pair of chambers, and the method can also include providing the first rotational fluid at the first pressure to the first opposing pair of chambers, and providing the second rotational fluid at the second pressure to the second opposing pair of chambers. The first end of the stationary vane member can also include a first fluid port formed therethrough and the second end includes a second fluid port formed therethrough, and wherein providing the rotational fluid at a first pressure is provided through the first fluid port and providing the rotational fluid at a second pressure is provided through the second fluid port. 
         [0009]    The systems and techniques described here may provide one or more of the following advantages. First, a system can provide a butterfly valve with a relatively smaller packaging envelope and/or less weight than other butterfly valves of similar capacity. Second, the described butterfly valve can be provided with a reduced number of component parts compared to other butterfly valves of similar capacity. Third, the described butterfly valve can provide increased control position precision. Fourth, the described butterfly valve can provide relatively stiffer direct hydraulic actuation coupling. Fifth, the described butterfly valve can provide increased unit vibratory resistance. 
         [0010]    The details of one or more implementations are set forth in the accompanying drawings and the description below. Other features and advantages will be apparent from the description and drawings, and from the claims. 
     
    
     
       DESCRIPTION OF DRAWINGS 
         [0011]      FIG. 1A  is a perspective view of an example fluid-actuated butterfly valve assembly. 
           [0012]      FIG. 1B  is a cutaway partial perspective view of the example fluid-actuated butterfly valve assembly of  FIG. 1A . 
           [0013]      FIG. 2A  is a cross-sectional side view of the example fluid-actuated butterfly valve assembly of  FIG. 1A . 
           [0014]      FIG. 2B  is a cutaway perspective view of the example fluid-actuated butterfly valve assembly of  FIG. 1A . 
           [0015]      FIG. 3A  is a top view of opposing stationary vane members (stator vanes) and a rotating collar assembly (rotor ring) in an actuator portion of the example fluid-actuated butterfly valve assembly of  FIG. 1A . 
           [0016]      FIG. 3B  is a cutaway perspective view of the opposing stationary vane member and a rotating collar assembly of the actuator portion of the example fluid-actuated butterfly valve assembly of  FIG. 3A . 
           [0017]      FIG. 3C  is a perspective view of the stationary vane member of  FIG. 3A . 
           [0018]      FIG. 3D  is a perspective view of the actuator portion of  FIG. 3B . 
           [0019]      FIG. 4A  is a perspective view of a closure disc and actuator portion components of an example fluid-actuated butterfly valve actuator of  FIG. 1A . 
           [0020]      FIG. 4B  is a cutaway perspective view of the example fluid-actuated butterfly valve actuator of  FIG. 4A . 
           [0021]      FIGS. 4C-4E  are cross-sectional side views of the example fluid-actuated butterfly valve actuator of  FIG. 4A  in three different rotational orientations. 
           [0022]      FIG. 5  is a perspective view of an example position sensor assembly in the example butterfly valve of  FIG. 1A . 
           [0023]      FIG. 6  is a flow chart illustrating operational steps for the fluid actuated butterfly valve of  FIGS. 1A to 5 . 
       
    
    
     DETAILED DESCRIPTION 
       [0024]      FIG. 1A  is a perspective view of an example fluid-actuated butterfly valve assembly  100 . In general, the fluid-actuated butterfly valve assembly  100  is a butterfly valve in which the butterfly plate is integral with a rotating housing of a fluid-actuated vane actuator extending into a flow path  102  of the fluid to be controlled. The assembly  100  includes a flow body  110  and a fluid-actuated butterfly valve actuator assembly  200  that will be discussed further in the descriptions of  FIGS. 1B-5 . The flow path  102  passes through a central bore  104  of the flow body  110 . 
         [0025]    The fluid-actuated butterfly valve actuator assembly  200  includes a top cap assembly  210 .  FIG. 1B  is a cutaway perspective view of the top cap assembly  210 . The top cap assembly  210  includes a fluid conduit  220 , a fluid conduit  222 , and a drain conduit  224 . The fluid conduit  220  is fluidically coupled to a fluid fitting  320 , the fluid conduit  222  is fluidically coupled to a fluid fitting  322 , and the drain conduit  224  is fluidically coupled to a fluid fitting  324 . 
         [0026]    The fluid conduits  220 - 222  are fluidically coupled to fluid chambers within the fluid-actuated butterfly valve actuator assembly  200 . Pressurized fluid (e.g., control fluid) can be controllably applied to the fluid conduits  220 - 222  to actuate the fluid-actuated butterfly valve assembly  100  to move a closure member in the fluid actuated valve assembly  100  to control the flow of a controlled fluid through the flow body  110 . In some implementations, the pressurized fluid can be a liquid (e.g., oil, hydraulic fluid, water) or a gas (e.g., air, nitrogen, CO2). The drain conduit  224  is fluidically coupled to drain cavities within the assembly  200 . Excess fluid, e.g., leakage fluid, collected within the drain cavities flows out the drain conduit  224 . The fluid chambers and drain cavities are discussed further in the descriptions of  FIGS. 2A ,  3 A, and  3 B. 
         [0027]    An electrical conduit  226  accommodates an electrical cable  228 . The electrical cable  228  conducts one or more electrical signals between an electrical connector  238  and a position sensor or encoder (not shown). The position encoder is discussed further in the descriptions of  FIGS. 2A and 5 . A collection of fastener bores  240  are provided to accommodate a collection of fasteners  242  (e.g., bolts, screws) to secure the top cap assembly  210  to the fluid-actuated butterfly valve assembly  200 . 
         [0028]      FIG. 2A  is a cross-sectional side view of the example fluid-actuated butterfly valve assembly  100 . Visible in this view are the flow body  110 , the fluid-actuated butterfly valve actuator assembly  200 , and the top cap assembly  210 . The top cap assembly  210  is shown with one of the fasteners  242  passed through the fastener bore  240  to removably affix the top cap assembly  210  to a stationary shaft  310  of a fluid-actuated butterfly valve actuator  300 . The actuator  300  extends into the central bore  104  and the flow path  102  of the fluid to be controlled. The fluid conduit  220  aligns with and fluidically connects to a fluid conduit  320  formed in the stationary shaft  310 . The fluid conduit  222  aligns with and fluidically connects to a fluid conduit  322  also formed in the stationary shaft  310 . 
         [0029]    Referring now to  FIGS. 3A-3D , the example fluid-actuated butterfly valve actuator  300  will be discussed.  FIG. 3A  is a top view of the example fluid-actuated butterfly valve actuator  300 ,  FIG. 3B  is a cutaway perspective view of the example fluid-actuated butterfly valve actuator  300 , and  FIG. 3C  is a perspective view of the example fluid-actuated butterfly valve actuator  300 . The assembly includes the stationary shaft  310  and a rotor ring  400 . 
         [0030]    In general terms, the fluid-actuated butterfly valve actuator  300  is similar to a rotary vane actuator (RVA). Most RVAs used implement a stationary housing with stator members and with a rotatable central shaft with attached vane members wherein the vane members affixed to the rotating shaft can be urged to rotate (e.g., rotary vane members) through the application of pressurized fluids to the rotary vane members provided through conduits formed in the stationary housing. However, in the example of the fluid-actuated butterfly valve actuator  300  of the present disclosure, the stationary shaft  310  is held substantially stationary (e.g., relative to the flow body  110 ), while fluid pressure applied through the fluid conduits  320 - 322  is used to urge bidirectional rotation of the rotor ring (a/k/a rotating collar assembly)  400  about the stationary shaft  310 . 
         [0031]    The rotor ring  400  includes a cylindrical bore  402 . The cylindrical bore  402  is a chamber that encloses stationary shaft  310 . The stationary shaft  310  is a machined cylindrical component consisting of a first stator vane  312   a , a second stator vane  312   b  and a centered cylindrical hub  314 . In some embodiments, the diameter and linear dimensions of the first and second stator vanes  312   a ,  312   b  are equivalent to the diameter and depth of the cylindrical bore  402 . 
         [0032]    The rotor ring is able to rotate about 90 degrees in both a clockwise and counterclockwise direction relative to the stationary shaft  310 . Within the cylindrical bore  402 , the rotor ring  400  includes a first member  404   a  and a second member  404   b . The stator vanes  312   a  and  312   b  act as stops for the rotor ring  400  and prevent further rotational movement of the rotor ring  400 . A collection of outside lateral surfaces  406  of the members  404   a  and  404   b  provide the stops for the rotor ring  400 . 
         [0033]    The first and second stator vanes  312   a  and  312   b  include a groove  356 . As shown in  FIG. 3B , each of the grooves  356  includes one or more seals  358  configured to contact the wall of the cylindrical bore  402 . The first and second members  404   a  and  404   b  include a groove  460 . Each of the grooves  460  includes one or more corner seals  462  configured to contact the stationary shaft  310 . 
         [0034]    As seen in  FIG. 3D , a pair of corner seals  360  are in sealing contact about the outer circumference of the cylindrical hub  314 . The corner seals  360  are compliantly urged into sealing contact with an upper longitudinal end  440   a  and a lower longitudinal end  440   b  of the rotor ring  400  by a pair of spring energizers  361 . The corner seals  360  are also urged into sealing contact with the upper longitudinal end  440   a  and the lower longitudinal end  440   b  of the rotor ring  400  by pressurized fluid provided through pair of fluid passages  470  which will be discussed further in the description of  FIG. 3E . 
         [0035]    Referring once again to  FIGS. 3B and 3C , the seals  358  and the corner seals  360  and  462  radially define a pair of pressure chambers  340   a  positioned radially opposite of each other across the stationary shaft  310 , and a pair of opposing pressure chambers  340   b  positioned radially opposite each other across the stationary shaft  310 . In use, fluid is introduced or removed from the pressure chambers  340   a  and  340   b  through the fluid conduits  320 ,  322 , and a pair of fluid ports  323  exposed to the pressure chambers  340   a ,  340   b . Rotational fluid at a first pressure can be provided through one or more of the fluid ports  323  and rotational fluid at a second pressure can be provided through another one or more of the fluid ports  323 . For example, fluid can be applied at the fluid port  320  and flowed to the chambers  340   a  through the fluid ports  323 . Similarly, fluid can be applied at the fluid port  322  and flowed through the fluid ports  323  to the chambers  340   b . In some implementations, the stator vanes  312   a ,  312   b  can include the fluid ports  323  formed therethrough. 
         [0036]    The pressure chambers  340   a ,  340   b  are defined longitudinally by a rotor housing  450  and an actuator cap  290  that will be discussed further in the descriptions of  FIGS. 2A-2B  and  4 A- 4 E below. By creating a fluid pressure differential between the pressure chambers  340   a  and the pressure chambers  340   b , the rotor ring  400  can be urged to rotate clockwise or counterclockwise relative to the stationary shaft  310 . 
         [0037]    As seen in  FIGS. 3D and 4C , a collection of dynamic seals  330   a - 330   d  is in sealing contact about the outer circumference of the cylindrical hub  314 . The dynamic seals  330   b  and  330   c  are positioned along the cylindrical hub  314  longitudinally outward from the corner seals. The dynamic seal  330   a  is positioned longitudinally further outward from the seal  330   b  along the cylindrical hub  314  such that a drain port  332   a  is located between the dynamic seals  330   a  and the dynamic seal  330   b . Similarly, the dynamic seal  330   d  is positioned longitudinally further outward from the seal  330   c  along the cylindrical hub  314  such that a drain port  332   b  is located between the dynamic seals  330   c  and the dynamic seal  330   d.    
         [0038]    The drain ports  332   a ,  332   b  are in fluidic communication with the drain conduit  324 . Fluid leaking longitudinally away from the pressure chambers  340   a ,  340   b  and past the dynamic seal  330   b  will be blocked by the dynamic seal  330   a  and allowed to flow out the drain port  332   a . Similarly, fluid leaking longitudinally away from the pressure chambers  340   a ,  340   b  and past the dynamic seal  330   c  will be blocked by the dynamic seal  330   d  and allowed to flow out the drain port  332   b.    
         [0039]      FIG. 4A  is a perspective view of a closure member and actuator portion components of the example fluid-actuated butterfly valve actuator  300 , and  FIG. 4B  is a cutaway perspective view of the example fluid-actuated butterfly valve actuator  300 .  FIGS. 4C-4E  are cross-sectional side views of an example fluid-actuated butterfly valve actuator  300  in three different rotational orientations. The rotor housing  450  includes a closure disc  452  that is configured to rotate within the central bore  104  between at least a substantially parallel orientation and a substantially perpendicular orientation relative to the flow path  102 .  FIG. 4C  shows the actuator  300  in a cross-section taken substantially perpendicular (e.g., 90 degrees) to the orientation of the closure disc  452  and the view shown in  FIG. 2A .  FIGS. 4D and 4E  show the actuator  300  in cross-sections taken at approximately 25 degree and approximately 66 degree orientations, respectively. 
         [0040]    In the views of  FIGS. 4D  and- 4 E, the rotor ring  400  is shown removably connected to the rotor housing  450  and the actuator cap  290  by a collection of locating pins  468 , also illustrated in  FIG. 3D . The rotor ring  400  is removably secured to the rotor housing  450  longitudinally by the actuator cap  290 . A pair of seals  466  is in sealing contact between the outer periphery of the actuator cap  290  and the rotor housing  450 . In some implementations, the seals  358 ,  462 , and  330   a - 330   d  can be 0-rings, X-rings, Q-rings, D-rings, energized seals, or combinations of these and/or any other appropriate form of seals. 
         [0041]    The fluid-actuated butterfly valve actuator  300  includes a position sensor assembly  500 . The position sensor includes a housing  510  and an input shaft  520 . The position sensor assembly  500  includes electromechanical components that can sense rotation of the input shaft  520  relative to the housing  510 , and encode and transmit signals indicative of the rotational position of the input shaft  520  relative to the housing  510 . Referring to  FIG. 4C , signals provided by the position sensor assembly  500  are transmitted to external devices through the electrical cable  228  that runs through the conduit  226 . 
         [0042]    The housing  510  is removably coupled to the stationary shaft  310  and remains substantially motionless relative to the stationary shaft  310 . The input shaft  520  is removably coupled to the rotor housing  450  via splines on the shaft  520  and mating splines on the housing  450 . As the rotor housing  450  is rotated by the rotor ring  400  relative to the stationary shaft  310 , the input shaft  520  is proportionally rotated relative to the housing  510  such that the position of the rotor housing  450  and the closure disc  452  relative to the flow path  102  in the flow body  110  can be sensed by the position sensor assembly  500  and provided to other equipment. In some embodiments, position signals provided by the position sensor assembly  500  can be used as feedback in a position control loop to adjust the position of the closure disc  452  and control the volume and rate of flow through the valve  100 . 
         [0043]    Referring now to  FIG. 5 , a perspective view of the example position sensor assembly  500  is shown. Visible are the housing  510  and the input shaft  520 . Also visible is a spanner nut  530 . Referring again to  FIGS. 4B-4E , the spanner nut  530  is also visible. During assembly of the fluid-actuated butterfly valve actuator assembly  200 , the position sensor  500  is removably affixed to the cylindrical hub  314  by the spanner nut  530 . In some embodiments, the position sensor  500  can include tabs that can guide the sensor  500  into a predetermined position. The spanner nut  530  can then be pressed against the tabs and provide mechanical locking of the position sensor  500  to the stationary shaft  310 . 
         [0044]    Referring again to  FIGS. 3A ,  3 B,  3 D, and  4 E, the rotor ring  400  includes the pair of fluid passages  470 . As best seen in  FIG. 4E , the fluid passages  470  are in fluidic communication with a pair of fluid passages  292  within the actuator cap and a pair of fluid passages  592  within the rotor housing  450 . The fluid passages  470 ,  292 , and  592  are in fluidic communication with a pair of fluid chambers  294  that are exposed to the corner seals  360 . In some implementations, fluid pressure can be provided to the fluid passages  470 ,  292 , and  592  to load the corner seals  360  at the higher of the two fluid pressures present in the fluid chambers  340   a ,  340   b.    
         [0045]      FIG. 6  is a flow diagram of an example process  600  for rotating a fluid-actuated butterfly valve assembly (e.g., the fluid-actuated butterfly valve assembly  100  of  FIG. 1A ). At step  610 , the flow body  110  is provided. At step  620  the stationary shaft  310  is provided. For example, as shown in  FIGS. 2A and 2B , the stationary shaft  310  extends into the flow path  102  that passes through the central bore  104  of the flow body  110 . The stationary shaft  310  includes the stator vanes  312   a  and  312   b.    
         [0046]    At  630 , the rotor ring  400  is provided. For example, as shown in  FIGS. 2A and 2B , the rotor ring  400  is placed about the stationary shaft  310 . The rotor ring  400  includes first member  404   a  and the second member  404   b . In some embodiments, the first member  404   a  and the second member  404   b  can be part of the actuator cap  290 . 
         [0047]    At  640 , the rotor housing  450  is provided. For example, as shown in  FIGS. 2A and 2B , the rotor housing  450  is placed about the rotor ring  400  and the stationary shaft  310 . The rotor housing  450  is removably coupled to the rotor ring  400 . In some implementations, the rotor ring  400  may be formed integrally with the rotor housing  450 . 
         [0048]    At step  650 , a rotational fluid is provided at a first pressure and contacting the first vane with the first rotational fluid. For example, hydraulic fluid can be applied through the fluid port  322  to the chambers  340   b.    
         [0049]    At step  660 , a rotational fluid is provided at a second pressure less than the first pressure and contacting the second vane with the second rotational fluid. For example, as the rotor assembly rotates clockwise, fluid in the fluid chambers  340   a  is displaced and flows out through the fluid port  320 . 
         [0050]    At step  670 , the rotor ring  400  and the rotor housing  450  are rotated in a first direction of rotation. For example, the rotor ring  400  and the rotor housing  450  can start in a position in which the closure disc  452  is substantially parallel to the flow path  102 , as illustrated in  FIGS. 2A and 2B . As fluids are controllably applied to the fluid chambers  340   a ,  340   b , the disc  452  can be rotated away from the parallel orientation, progressively blocking the flow path  102 . Motion of the rotor ring  400  along an approximately 90 degree range of motion urges rotation of the rotor housing  450  between its substantially perpendicular and parallel positions relative to the flow path  102 , selectively blocking and permitting fluid flow through the flow body central cavity  104 . 
         [0051]    Rotation of the rotor ring  400  is transferred to the rotor housing  450 . As the rotor ring  400  rotates, the rotor housing  450  is also urged to rotate. The rotor housing  450  includes the disc  452  that is configured to rotate within the central bore  104  between at least a substantially parallel orientation and a substantially perpendicular orientation relative to the flow path  102 . The disc  452  is configured with a thickness that substantially allows fluid to flow through the flow body  110  while the disc is substantially parallel to flow path  102 , and the disc  452  is configured with a diameter that substantially blocks fluid flow through the flow body  110  while the disc is substantially perpendicular to the flow path  102 . 
         [0052]    At step  680 , the rotation of the rotor ring  400  and the rotor housing  450  is stopped by contacting at least one of the outside lateral surfaces  406  with at least one of the stator vanes  312   a ,  312   b . For example,  FIG. 2A  illustrates the rotor ring  400  with the members  404   a ,  404   b  in contact with the stator vanes  312   a ,  312   b.    
         [0053]    In some implementations, the rotor assembly can be rotated in the opposite direction to the first direction of rotation by increasing the second pressure and reducing the first pressure until the second pressure is greater than the first pressure. In some implementations, the rotation of the rotor assembly in the opposite direction can be stopped by contacting opposite sides of at least one of the members  404   a ,  404   b  with the stator vanes  312   a ,  312   b.    
         [0054]    Although the example fluid-actuated butterfly valve assembly  100  is described as having a pair of the stator vanes  312   a - 312   b  and a pair of the members  404   a - 404   b  to form opposing pairs of the pressure chambers  340   a - 340   b , other embodiments can exist. In some embodiments, the fluid-actuated butterfly valve assembly  100  can include a single one of the stator vanes  312   a  or  213   b  and a single one of the members  404   a  or  404   b . For example, the pressure chambers on each side of a single member connected to the rotor ring  400  may be pressurized and depressurized to rotate the member away from contacting a first side of a single stator, and rotate the member about 270 degrees to contact a second side of the single stator. Rotation in the opposite direction can be accomplished by reversing the pressurization of the pressure chambers. 
         [0055]    Although a few implementations have been described in detail above, other modifications are possible. For example, the logic flows depicted in the figures do not require the particular order shown, or sequential order, to achieve desirable results. In addition, other steps may be provided, or steps may be eliminated, from the described flows, and other components may be added to, or removed from, the described systems. Accordingly, other implementations are within the scope of the following claims.