Patent Publication Number: US-2007108402-A1

Title: Sealed hub for motor actuated valve

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
      This application claims the benefit of U.S. Provisional Application No. 60/736,535, filed on Nov. 14, 2005. The disclosure of the above application is incorporated herein by reference. 
    
    
     FIELD  
      The present invention relates in general to motor actuated valves and more specifically to a device and method for sealing a connection between a valve and a valve actuator.  
     BACKGROUND  
      Valves are commonly operated by installation of a motor operated actuator which is installed on the valve and externally connected by a connector assembly to a stem or stem extension of the valve. Certain valve designs provide stem geometries which require the stem to be loaded through the valve internal cavity. The valve must therefore be disassembled for maintenance access to the stem and/or stem seals. Valves in some applications including but not limited to refrigerant service valves have body connections which are welded or sealed in a manner which does not permit subsequent access to the internal components of the valve to replace items such as gaskets, seals or internal components. In these applications, if the stem seals leak, access through the valve body to the stem seals is not a cost effective option.  
      A method and device to externally seal a leaking stem area is therefore desirable for motor actuated valves. For motor operated valves, removal and reassembly of the actuator must also be considered when repairing the leaking stem to ensure the actuator can be reassembled and realigned for proper operation of the valve.  
     SUMMARY  
      According to some embodiments of the present invention, a sealing hub assembly is adapted for installation to a motor actuated valve. The sealing hub assembly includes a hub body adapted to engage a stem boss of the valve, and is operable to releasably mount a motor/actuator. An adapter member is internally received within the hub body. A stem extender is retained by the adapter member. The stem extender is coupled at a first end for co-rotation with a stem of the valve, and is coupled at a second end to the motor/actuator. A first seal is disposed between the stem extender and the adapter.  
      According to further embodiments, a sealing hub assembly is provided for a valve having a stem boss and a stem rotatably received in the stem boss. The stem is normally rotated by a motor/actuator. To seal a leaking stem, a hub body is connected to the stem boss which is also used to releasably mount the motor/actuator. An adapter is threaded into the hub body. A stem extender is rotatably supported in the adapter and is coupled at a first end for co-rotation with the stem, and coupled at a second end to the motor/actuator. To provide an external fluid seal for the leaking stem, a first seal is positioned between the stem extender and the adapter, and a second seal is positioned between the adapter and the stem boss.  
      According to still further embodiments, a method is provided for installing a sealing assembly between a valve and a valve motor/actuator which is operable to externally seal a leaking stem seal. The sealing assembly has a cylindrical portion and flange portion, an adapter engageable to the cylindrical portion, and a stem extender. The valve has a stem rotatably received within a stem boss. The method includes positioning the first sealing member on the stem extender. The method also includes inserting the stem extender into the adapter to operably engage the first sealing member between the stem extender and the adapter. The method further includes urging the adapter into engagement with the flange portion. The method still further includes positioning a second sealing member between the adapter and the stem boss. The method yet further includes releasably engaging the cylindrical portion to the stem boss to operably engage the second sealing member to both the adapter and the stem boss.  
      A sealed hub assembly of the present invention offers several advantages. By using sealing elements which are positioned external to the valve assembly, any leaking seals of an existing valve which would otherwise permit atmospheric leakage are isolated. The sealed hub assembly of the present invention also provides simple mechanical connection to an existing body stem boss without further modification or machining of the body stem boss. This permits for rapid installation of a sealed hub assembly of the present invention for the existing connectors of body stem boss  52 . A further advantage is provided by stem extender  38  which adapts to the existing or other known motor actuators with minimal power loss. The various sealing elements of a sealed hub assembly of the present teachings are also themselves easily replaceable if subsequent leakage past these seal elements occurs.  
      Further areas of applicability of the present teachings will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating several embodiments of the present teachings, are intended for purposes of illustration only and are not intended to limit the scope of the teachings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The present teachings will become more fully understood from the detailed description and the accompanying drawings, wherein:  
       FIG. 1  is a perspective view of a valve assembly including a sealed hub of the present teachings;  
       FIG. 2  is a side elevational view of the valve assembly of  FIG. 1 ;  
       FIG. 3  is a cross sectional side elevational view of the valve assembly of  FIG. 2 ;  
       FIG. 4  is an end elevational view at end  4  of  FIG. 2 ;  
       FIG. 5  is a top plan view taken at section  5 - 5  of  FIG. 4 ;  
       FIG. 6  is an enlarged cross sectional view taken at area  6  of  FIG. 3 ;  
       FIG. 7  is a side elevational view of a stem extender of the present teachings; and  
       FIG. 8  is a cross sectional side elevational view of an adapter of the present teachings. 
    
    
     DETAILED DESCRIPTION  
      The following description of several embodiments of the present teachings is merely exemplary in nature and is in no way intended to limit the present teachings, their application, or uses.  
      According to several embodiments of the present teachings and with reference to  FIG. 1 , a valve assembly  10  includes a valve  12  having a connected motor/actuator  14 . Motor/actuator  14  can be an electric, a hydraulic, or a pneumatic motor. A sealed hub assembly  15  adaptably connects motor/actuator  14  to valve  12  and provides additional sealing capability to prevent leakage of system fluid past the primary stem seals from escaping to atmosphere.  
      Valve  12  further includes an inlet branch  18  having an inlet adapter  20  and an outlet branch  22  having an outlet adapter  24 . The designation of “inlet” and “outlet” branches is for convenience only, as the configuration of valve  12  can include the inlet or the outlet at either end of valve  12 . A branch connector port  26  is connected for example to inlet branch  18 . Branch connector port  26  provides a mechanical connection for a hose or tube to be temporarily or permanently connected to valve  12 . Branch connector port  26  therefore allows system fluid to be added or bled from the fluid system to which valve  12  is connected. If the hose or tube (not shown) is not connected to branch connector port  26 , a seal cap  27  is installed to act as a fluid system boundary.  
      Sealed hub assembly  15  includes a hub body  28  which is connected to valve body  16 . Hub body  28  includes a radial flange  30 . Motor/actuator  14  is connected to radial flange  30  by joining a motor first or bottom face  32  with a flange first or upper face  34  of radial flange  30 . An adjustment device  36  is also commonly provided with motor/actuator  14 . Adjustment device  36  can be used to control the total rotational displacement of a stem extender  38  and thereby control a degree of rotational movement of an isolation member (for example a ball with flow ports) provided within valve body  16 . A power source line  40  is also commonly provided with motor/actuator  14 . Power source line  40  in some embodiments is an electrical power cord for providing for example alternating current or direct current electrical voltage to operate motor/actuator  14 . In other embodiments, power source line  40  can provide one or more hydraulic or pneumatic tubes to support hydraulic or pneumatic operation of motor/actuator  14 .  
      As best seen in reference to  FIG. 2 , sealed hub assembly  15  is advantageously used for valves  12  which have sealed body connections. For example, an end fitting  42  is sealed to valve body  16  with a seal joint  44  which in some embodiments is a weld joint or brazed joint. Inlet branch  18  is sealed to valve body  16  using an inlet branch seal joint  46  which in some embodiments is a weld joint or a brazed joint. Similarly, outlet branch  22  is sealed to end fitting  42  using an outlet branch seal joint  48  which again can include a weld joint or a brazed joint. Valve  12  can also be provided with a body support member  50  which commonly acts as a body mounting attachment for valve  12  to structure or other system components. Valves  12  having sealed joints as noted herein are commonly used in fluid applications where atmospheric leakage is unacceptable. For example, such fluid applications include refrigerant service. The complications created by sealing the various joints of valve  12  include the difficulty of subsequent removal and maintenance of sealing members used within valve  12 .  
      When valves  12  are sealed as described above, leakage of system fluid in the area of a body stem boss  52  can create flow paths for system fluids directly to the atmosphere. It is in part to correct or eliminate this leakage path that sealed hub assembly  15  is provided. Sealed hub assembly  15  further includes a cylinder section of hub body  28  which is mechanically connected to body stem boss  52  using a retention element  56 . Examples of retention elements  56  included threaded pin elements, through-pin elements or similar fasteners.  
      With further reference to  FIG. 2 , one or more fasteners  58  mechanically connect motor/actuator  14  to radial flange  30  by inserting fastener(s)  58  from a flange lower face  60  side of radial flange  30 . An adjustment element  62  can also be provided with adjustment device  36 . Examples of adjustment elements  62  include hex or square ended threaded fasteners to which a tool (not shown) can be used to apply a torque to adjustment element  62  to effectively lock adjustment device  36  in position.  
      Referring now generally to  FIG. 3 , and for exemplary purposes only, valve  12  is hereinafter described in reference to a ball valve having a ball  64  rotatably disposed within valve body  16 . Valve  12  is not limited to ball valves, and other rotationally operated valves such as gate, globe and throttling valves can also be used. Ball  64  is provided with first and second ball seals  66 ,  68  proximate to flow port connections servicing each of inlet and outlet branches  18 ,  22 . A ball through-bore  70  includes a ball through-bore diameter “A” which in some embodiments is sized to substantially equal each of an inlet branch bore diameter “B” of inlet branch  18  and an outlet branch bore diameter “C” of outlet branch  22 . Ball  64  is rotatably actuated by rotation of a main stem  72 . Main stem  72  includes a male element  74  which is connectably fitted within a slot  76  created in ball  64 . Main stem  72  is provided with first seal elements  78 , such as O-rings, to provide a primary fluid boundary seal between main stem  72  and body stem boss  52 .  
      In applications where high pressure within valve body  16  could otherwise adversely tend to drive main stem  72  outwardly, a stem radial flange  80  is often provided. Stem radial flange  80  abuts with a shoulder area internally positioned within body stem boss  52  to prevent outward displacement of main stem  72 . When stem radial flanges  80  are used, however, and particularly with valve designs having sealed end connections, leakage of first seal elements  78  would require disassembly of the various sealed joints of valve  12  to allow removal of ball  64  and main stem  72  to replace first seal elements  78 . Due to the obvious cost and difficulty of disassembling valve  12  in this manner, sealed hub assembly  15  is provided to add additional external seals to prevent system fluid escaping past first seal elements  78  from escaping to the atmosphere.  
      To provide this additional external sealing function, sealed hub assembly  15  further includes an adapter sleeve  82  which is internally positioned within hub body  28  and rotatably supports stem extender  38 . Adapter sleeve  82  is retained within hub body  28  using for example a threaded joint  84 . An aperture  86  previously created in main stem  72  receives retention element  56  having a portion which extends beyond main stem  72  to be received in one or more recesses (not shown) on an end face of stem boss  52 . Retention element  56  engages end faces (not shown) of the recess(es) to limit rotation of main stem  72  to a predetermined arc of rotation, normally 90 degrees for a ball valve. A shoulder portion  88  of adapter sleeve  82  acts as a retention element to retain an extension stem radial flange  90  of stem extender  38 . Shoulder portion  88  prevents outward displacement in a displacement direction “D” of stem extender  38 . Extension stem radial flange  90  therefore has a similar function to stem radial flange  80 . At least one and in several embodiments a plurality of second seal elements  92  are disposed about stem extender  38  to provide an additional fluid seal between stem extender  38  and an inner bore wall of adapter sleeve  82 . In some embodiments, second seal elements  92  are O-rings of a polymeric or a rubber type material. Second seal elements  92  also permit rotational displacement of stem extender  38  while simultaneously providing a fluid boundary seal. Each of the stem extender  38  and main stem  72  commonly rotate about a ball-stem rotational axis  94 .  
      Referring now generally to  FIG. 4 , a sleeve member  96  of adapter sleeve  82  extends beyond radial flange  30  as shown and rotatably receives stem extender  38 . A bearing sleeve  98  is provided with motor/actuator  14  to also rotatably receive stem extender  38 . A connecting joint  100  which in several embodiments of the present teachings includes a threaded joint is provided on body stem boss  52  to mechanically couple cylinder section  54  of hub body  28  to body stem boss  52 . Cylinder section  54  is adapted to engage with connecting joint  100  which is previously provided with valve  12 , and otherwise receives an end cap which normally retains main stem  72 . This cap (not shown) is removed prior to installation of cylinder section  54  of sealed hub assembly  15 . A male element  102  can be provided at a distal end of stem extender  38  similar to male element  74  of main stem  72 . Male element  102  can be provided for example for attachment of a retention tool during adjustment of adjustment device  36 . Male element  102  can also functionally receive a tool such as a wrench which can be used to manually rotate stem extender  38  and thereby main stem  72 , to manually actuate ball  64  if power is not available to motor/actuator  14 . Branch connector port  26  is shown substantially co-axially aligned with ball/stem rotational axis  94 , however, branch connector port  26  can be rotated about inlet branch  18  to an alternate position from that shown.  
      Referring now generally to  FIG. 5 , a first, second, third and fourth fastener aperture  104 ,  106 ,  108 ,  110  are created in radial flange  30  and sized accordingly to receive fasteners  58  used to connect motor/actuator  14  to valve body  16 . Radial flange  30  is aligned with a valve longitudinal axis  112 .  
      Referring in general now to  FIG. 6 , further details of sealed hub assembly  15  are shown. Also shown are one or more annular grooves  114  created about main stem  72  which receive each of first seal elements  78 . First seal elements  78  therefore seat against an inner face  116  of body stem boss  52 . Fluid leakage past any of first seal elements  78  is retained by sealed hub assembly  15 . To rotatably engage stem extender  38  with main stem  72 , a slotted end  118  of stem extender  38  is engaged with a male end  119  of main stem  72 . A first washer-type seal element  120  created of a polymeric or similar sealing material can be disposed between an end face of body stem boss  52  and a corresponding end face of adapter sleeve  82 . In other embodiments, a second washer-type seal element  122 , which is used in lieu of first washer-type seal element  120 , can be positioned between an exterior radial face  123  of adapter sleeve  82  and an inner face  124  of radial flange  30  proximate to an aperture  125  created in radial flange  30 . When second washer-type seal element  122  is used, an additional seal (not shown) is also provided between cylinder section  54  and stem boss  52 . Use of first washer-type seal element  120  does not require the further seal at cylinder section  54  and is therefore a less complex/expensive option. To further control any leakage of fluid past first seal elements  78 , and to control the location of the second seal elements  92 , at least one and in some embodiments a plurality of annular grooves  126  are created in stem extender  38 , each receiving one of the second seal elements  92 . Second seal elements  92  therefore provide a fluid seal between stem extender  38  and an inner face  128  of adapter sleeve  82  while permitting rotation of stem extender  38 .  
      First or second washer-type seal elements  120 , 122  and second seal elements  92  therefore define external boundaries for preventing fluid leakage past first seal elements  78  from escaping to the atmosphere. By positioning each of the sealing elements external to main stem  72 , the internal components of valve  12  do not have to be removed in order to repair a leaking valve  12 . Sealing pressure for first or second washer-type seal elements  120 ,  122  is provided by engaging hub body  28  with body stem boss  52  in an engagement direction “E” using connecting joint  100  and threaded joint  84 .  
      Referring now to  FIG. 7 , stem extender  38  further includes a cylindrical shaft  130  positioned between male element  102  and slotted end  118 . Cylindrical shaft  130  has a shaft diameter “F” sized to be rotatably received against inner diameter face  128  of adapter sleeve  82 . Slotted end  118  includes an end face  132  created in a cylindrical head  134 . Cylindrical head  134  has a head diameter “G” which is greater than shaft diameter “F”. Opposed first and second slot walls  136 ,  138  extend perpendicularly with respect to end face  132 . First and second slot walls  136 ,  138  engage male end  119  of main stem  72  to transfer the rotational torque of motor/actuator  14  to main stem  72 . Annular grooves  126  are positioned proximate to cylindrical head  134 .  
      Referring now to  FIG. 8  and with further reference to  FIGS. 6 and 7 , adapter sleeve  82  includes an aperture  140  which rotatably receives cylindrical shaft  130  of stem extender  38 . A plurality of male threads  142  threadably engage corresponding female threads of cylinder section  54  to create threaded joint  84 . An outer sleeve  144  having a sleeve diameter “H” is received in aperture  125  of radial flange  30 . First and second engagement faces  146 ,  147  are created in outer sleeve  144  to act as tool engagement faces for rotationally tightening adapter sleeve  82  in cylinder section  54  of hub body  28 . An inner shoulder  148  engages extension stem radial flange  90  to retain stem extender  38 .  
      A sealed hub assembly of the present invention offers several advantages. By using sealing elements which are positioned external to the valve assembly, any leaking seals of an existing valve which would otherwise permit atmospheric leakage are isolated. The sealed hub assembly of the present invention also provides simple mechanical connection to an existing body stem boss without further modification or machining of the body stem boss. This permits for rapid installation of a sealed hub assembly of the present invention for the existing connectors of body stem boss  52 . A further advantage is provided by stem extender  38  which adapts to the existing or other known motor actuators with minimal power loss. The various sealing elements of a sealed hub assembly of the present teachings are also themselves easily replaceable if subsequent leakage past these seal elements occurs.  
      The description of the present teachings is merely exemplary in nature and, thus, variations that do not depart from the gist of the present teachings are intended to be within the scope of the present teachings. Such variations are not to be regarded as a departure from the spirit and scope of the present teachings.