Patent Publication Number: US-6988709-B2

Title: Bearing retainer for trunnion mounted ball valve

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates generally to ball valves, and more particularly, but not by way of limitation, to an improved bearing retainer and method of assembly for a trunnion ball valve. 
   2. Brief Description of Related Art 
   In the typical construction of a trunnion mounted ball valve, the ball is machined to provide “trunnions” that are mounted in bearings. The bearing-trunnion combination is intended to support the ball in a stationary position relative to the flow path, but allow rotation of the ball between an open position and a closed position. The ball engages a pair of seats to form a seal around the ball. The valve is sealed as a result of the upstream valve seat moving against the ball in response to the line pressure. This is in contrast to a floating ball valve where the ball moves along the flow path and seals against the downstream valve seat as a result of the pressure applied to the ball. 
   A variety of designs for trunnion type valves exist. Notable design differences include the manner in which an operating stem, used for rotating the ball, is assembled and retained. The stem can be inserted internally from within the body cavity. This is known as a “blow-out-proof” design because the stem cannot be removed without disassembling the valve. Another option is to assemble the stem externally and retain it with bolted glands or pins. Another notable difference is that the trunnions can be assembled internally or externally. When assembled externally they are commonly retained with bolted glands. Alternatively, the trunnions can be machined directly on the ball. The ball-trunnion combination can then be inserted internally along with a bearing retainer. 
   In designing a trunnion valve, the overall length is determined by industry accepted standards. Therefore, the body section of the valve is the only area that is subject to original design. To produce a valve which can compete economically in the market requires a design that minimizes the overall body size and total weight of materials used to produce the valve body. 
   The different types of valve construction noted above are the result of trading one feature to gain another with the usual result of a less than optimal design. For example, the “blow-out-proof” stem design is generally considered preferable because it cannot be accidentally removed under pressure. Its simplicity also makes it less expensive to produce when compared with all the extra pieces needed to retain an externally mounted stem. Unfortunately, the “blow-proof” stem is not often used because it requires the overall diameter of the valve body to be increased to allow enough room for the ball to be assembled with the stem protruding into the bore. The result of an increase in total weight negates any design savings because the body material is more expensive than the cost of the eliminated parts. The choice of trunnion design also has important tradeoffs. The external pins, bearings, and means of retention are expensive to produce but require a much smaller overall valve body diameter. Internal bearing retainers are simpler and less expensive to produce but generally require a considerable gap between the ball and the body. As a result, a much larger overall body diameter is needed. 
   A bearing retainer is used to retain a bearing through which the trunnion extends. The bearing retainer is also known as a “trunnion support” or a “trunnion block.” Some designs have modified the internal bearing retainer in an effort to minimize the necessary gap. For example, the bearing retainer can be provided with longitudinal edges that are shaped to better conform to the contour of the ball cavity of the body section. This reduces the gap considerably if an externally loaded stem is used. With an internally loaded stem design, the upper bearing retainer may be slotted on one side to permit the bearing retainer to be moved past the lower end of the stem during assembly of the ball and bearing retainer. However, a slotted bearing retainer reduces the bearing support area of the bearing retainer along the direction of the fluid flow. In turn, a larger bearing retainer and thus a larger valve body is often required to provide sufficient bearing support, thereby obviating the purpose of the slotted bearing retainer. 
   To this end, a need exists for an improved bearing retainer and method of assembly which permits a particularly small gap between the body and the ball while maintaining internal trunnions in a “blow-out-proof” stem and without sacrificing bearing load strength. It is to such an improved bearing retainer and method that the present invention is directed. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       FIG. 1  is a vertical cross section of a trunnion valve constructed in accordance with the present invention. 
       FIG. 2  is a perspective view of a retainer body constructed in accordance with the present invention. 
       FIG. 2A  is a side elevational view of the retainer body of  FIG. 2 . 
       FIG. 3  is a side elevational view of another embodiment of a retainer body constructed in accordance with the present invention. 
       FIG. 4  is a perspective view of another embodiment of a retainer body constructed in accordance with the present invention. 
       FIG. 5  is a horizontal cross section of the body of the valve with the valve member and retainer body positioned therein showing the slot of the bearing retainer oriented parallel with the direction of flow. 
       FIG. 6  is a cross sectional view showing the retainer body of  FIG. 5  rotated so that the slot of the bearing retainer is perpendicular to the direction of flow and the valve member in an open position. 
       FIG. 7  is a cross sectional view showing the retainer body of  FIG. 5  rotated so that the slot of the bearing retainer is perpendicular to the direction of flow and the valve member in a closed position. 
       FIG. 8  is a perspective view of a spacer constructed in accordance with the present invention. 
       FIG. 9  is a cross sectional side view of a portion of the valve showing one of the spacers in contact with the body of the valve. 
       FIG. 10  is a top plan view of a portion of the bearing retainer. 
       FIG. 11  is a perspective view of a ring spacer constructed in accordance with the present invention. 
       FIG. 12  is a partial, vertical cross section of another embodiment of a trunnion valve constructed in accordance with the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring now to the drawings, and more particularly to  FIG. 1 , shown therein is a valve  10  constructed in accordance with the present invention. The valve  10  includes a body assembly  12 , a valve member  14  disposed in the body assembly  12  for rotation between an open position ( FIG. 1 ) and a closed position ( FIG. 7 ), and a stem  16  for rotating the valve member  14  between the open position and closed position. The valve  10  further includes a pair of seat assemblies  18  and  20  for forming a seal between the body assembly  12  and the valve member  14 . 
   The body assembly  12 , as shown in  FIG. 1 , includes a body  22 , a first end adapter  24  connected to one end of the body  22 , and a second end adapter  26  connected to the opposing end of the body  22 . It will be appreciated by those of ordinary skill in the art that the body assembly  12  may be a two piece construction where one of the end adaptors  24  or  26  and the body  22  are integrally fabricated as one piece. 
   The body assembly  12  has a centrally disposed valve chamber  28 , and an inlet passage  30  and an outlet passage  32  in communication with the valve chamber  28  to form a flow passageway through the body assembly  12  about a longitudinal flow axis  34 . A first seat pocket  36  is formed about the inlet passage  30 , and a second seat pocket  38  is formed about the outlet passage  32 . The first seat pocket  36  is adapted to receive the seat assembly  18 , and the second seat pocket  38  is adapted to receive the seat assembly  20 . 
   The stem  16  extends through a stem bore  40  formed through the wall of the body  22 . The stem  16  has a lower portion  44  with an enlarged diameter. The lower portion  44  is adapted to be received in a corresponding enlarged diameter portion  46  of the stem bore  40 . The stem  16  is known as an “internally mounted” or “blow-out proof” stem. The stem  16  is mounted within the stem bore  40  in a manner well known in the art for rotation about a trunnion axis  48 . A key  50  (shown in FIGS.  1  and  5 – 7 ) is formed on the lower end of the stem  16 . The key  50  extends diametrically across the end of the stem  16  and is adapted to matingly engage with the valve member  14 . 
   The valve member  14  is mounted within the valve chamber  28  for rotation about the trunnion axis  48  between the opened position and the closed position wherein the valve member  14  is rotated substantially 90 degrees from the opened position to the closed position. The valve member  14  has a central bore  52  which aligns with the inlet passage  30  and the outlet passage  32  to permit the passage of fluid through the valve  10  when the valve member  14  is in the open position thereof. In the closed position of the valve member  14 , the seat assemblies  18  and  20  engage the exterior surface of the valve member  14  and internal surfaces of the body assembly  12  to form fluid tight seals which disrupt fluid communication between the inlet passage  30  and the outlet passage  32 . 
   The valve member  14  has the general form of a spherical ball with the central bore  52  formed therethrough extending circumaxially about a diameter thereof. Portions of the valve member  14  are cut away to form a circular first trunnion  54  and a circular second trunnion  56  which is diametrically opposed to the first trunnion  54  and coaxial therewith. A central slot  58  is formed in the distal end of the first trunnion  54  and, for reasons to be discussed below, is preferably oriented along a line parallel to the plane defined by the axis of the central bore  52  and the common axis of the first trunnion  54  and the second trunnion  56  when the valve member  14  is in the open position. The slot  58  is sized to receive the key  50  of the stem  16  so that the valve member  14  can be rotated about the trunnion axis  48  via rotation of the stem  16 . 
   A first trunnion bushing or bearing  60  is mounted on the first trunnion  54 , and a second trunnion bushing or bearing  62  is similarly mounted on the second trunnion  56 . A bearing retainer  64  is positioned about the first bearing  60  and extends longitudinally across the valve chamber  28  to engage opposing surfaces of the body assembly  12  so as to longitudinally support the first trunnion  54  of the valve member  14  within the valve chamber  28 . The bearing retainer  64  includes a retainer body  65  and a pair of spacers  66   a  and  66   b . The bearing retainer  64  is configured to allow for a small gap between the body  22  and the valve member  14  while permitting the use of an internally mounted stem without sacrificing bearing load strength. A bearing retainer  67  is positioned about the second trunnion bearing  62  and extends across the valve chamber  28  to engage opposing surfaces of the body assembly  12  so as to longitudinally support the second trunnion  56  within the valve chamber  28 . The construction of the bearing retainer  67  is similar to that of the bearing retainer  64 , except as noted below, in that it is configured to allow for a small gap between the body  22  and the valve member  14 . However, it will be appreciated that the bearing retainer  67  may also take the form of any suitable bearing retainer known in the art. 
   Referring now to  FIG. 2 , the retainer body  65  of the bearing retainer  64  is illustrated. The retainer body  65  is a generally frusto-conically shaped member constructed of a rigid and durable material, such as steel or stainless steel. The retainer body  65  has first side  70 , an opposing second side  72 , and a bearing receiving opening  74  extending from the first side  70  to the opposed second side  72 . The bearing receiving opening  74  is dimensioned to receive the first trunnion bearing  60  and the first trunnion  54  of the valve member  14  so that the valve member  14  is laterally supported in the valve chamber  28  while permitting the first trunnion  54  to rotate relative to the first trunnion bearing  60 . The retainer body  65  is provided with a lip  76  that extends radially into the bearing receiving opening  74  at the first end  70  of the retainer body  65  to the first trunnion bearing  60  within the bearing retaining opening  74 . 
   As shown in  FIG. 5 , to assemble the valve  10 , the valve member  14  is positioned in the valve chamber  28  of the body  22  with the first and second end adaptors  24  and  26  removed from the body  22 . Alternatively, if the body  22  is integrally formed with one of the end adapters, the free end adapter is removed from the body  22 . Prior to installing the valve member  14 , the stem  16  is inserted into the stem bore  40  from within the body  22 . With the stem  16  installed in the body  22 , the valve member  14  is installed into the valve chamber  28  with the first trunnion bearing  60  and the retainer body  65  positioned about the first trunnion  54 . To permit the bearing retainer  64  to be installed about the key  50  of the stem  16 , the retainer body  65  is provided with a stem receiving slot  78  ( FIGS. 2 and 5 ) formed in the first side  70  thereof in open communication with the bearing receiving opening  74 . The stem receiving slot  78  is dimensioned to permit the key  50  of the stem  16  to pass therethrough as the valve member  14 , together with the first trunnion bearing  60  and the retainer body  65 , is positioned in the valve chamber  28  when the key  50  is oriented in a parallel relationship with respect to the longitudinal flow axis  34 . It will be appreciated that the first trunnion bearing  60  is also provided with a slot  79  that is aligned with the stem receiving slot  78  so that the first trunnion bearing  60  is able to be moved freely past the key  50  of the stem  16 . Likewise, the second trunnion bearing  62  and the bearing retainer  67  are positioned about the second trunnion  56 . However, because the bearing retainer  67  does not interact with the stem  16 , the bearing retainer  67  does not require a stem receiving slot. 
   While the stem receiving slot  78  permits the retainer body  65  to be received about the key  50  of the stem  16 , the formation of the stem receiving slot  78  significantly reduces the bearing support surface along the longitudinal axis of the stem receiving slot  78 . The retainer body  65  is positioned in the valve body  22  or (valve chamber  28 ) with the longitudinal axis of the stem receiving slot  78  oriented in a parallel relationship with respect to the longitudinal flow axis  34 . It is appreciated by those of ordinary skill in the art that maximum loads on the retainer body  65  will occur along the line extending parallel to the longitudinal flow axis  34 . Therefore, when the retainer body  65  is positioned in the valve chamber  28  with the longitudinal axis of the stem receiving slot  78  oriented in a parallel relationship with respect to the longitudinal flow axis  34 , the strength of the retainer body  65  is compromised due to the reduced bearing support surface at the critical point. 
   To overcome the loss of critical bearing surface area at the stem receiving slot  78 , the retainer body  65  has a frusto-conical surface  82  ( FIG. 2 ) formed between the first side  70  and the second side  72  such that the retainer body  65  is rotatable, from an assembly position ( FIG. 5 ) to an operating position ( FIG. 6 ), within the valve chamber  28  about the first trunnion  54  upon the valve member  14 , the first trunnion bearing  60 , and the retainer body  65  being positioned in the valve chamber  28  with the key  50  of the stem  16  engaged with the valve member  14 . As such, the retainer body  65  may be rotated about the first trunnion  54  so that the stem receiving slot  78  is perpendicular to the longitudinal flow axis  34 . The weakened bearing surface area is thus rotated to a point where minimum loads are experienced. 
   As described above, the central slot  58  of the first trunnion  54  is preferably oriented along a line parallel to the plane defined by the axis of the central bore  52  and the common axis of the first trunnion  54  and the second trunnion  56 . As show in  FIG. 7 , this orientation has the effect of creating additional surface area for distributing loads when the valve member  14  is in the closed position and the load on the retainer body  65  is at its highest. 
   As best shown in  FIG. 2A , the frusto-conical surface  82  is radially turned such that the frusto-conical surface  82  has the contour of a portion of a standard cone. 
     FIG. 3  illustrates another embodiment of a retainer body  65   a  which is identical in construction to the retainer body  65  with exception that the retainer body  65   a  has a frusto-conical surface  82   a  which is spherically turned such that the frusto-conical surface  82   a  has the contour of a portion of a sphere. 
   Returning to  FIG. 2 , the retainer body  65  is further characterized as having a first planar end  84  and an opposing second planar end  86 . The first planar end  84  is formed so as to intersect the frusto-conical surface  82  and extend substantially parallel to the plane defined by the intersection of the longitudinal axis of the stem receiving slot  78  and the axis of the bearing receiving opening  74 . Likewise, the second planar end  86  intersects the frusto-conical surface  82  and extends substantially parallel to the plane defined by the intersection of the longitudinal axis of the stem receiving slot  78  and the axis of the bearing receiving opening  74 . The first planar end  84  and the second planar end  86  provide support surfaces for engagement with the first and second end adaptors  24  and  26  when the valve  10  is assembled. Each of the first planar end  84  and the second planar end  86  is provided with an opening  87  for connection of the spacers  66   a  and  66   b , respectively, in a manner to be discussed below. 
   The retainer body  65  further includes a third end  88  and a fourth end  90 . The third and fourth ends  88  and  90  are arc shaped and intersect the frusto-conical surface  82 . 
     FIG. 4  illustrates another embodiment of a retainer body  65   b  which is similar in construction to the retainer body  65  with the exception that the retainer body  65   b  has a third end  88   b  and a fourth end  90   b  which are formed to have a planar shape. As such, the retainer body  65   b  has a generally rectangular, frusto-conical shape. 
   It will be appreciated that when the retainer body  65  is formed to have a width from the first planar end  84  to the second planar end  86  that permits engagement of the first planar end  84  with the first end adaptor  24  and engagement of the second planar end  86  with the second end adaptor  26 , the area of the first planar end  84  and the second planar end  86  will be a relatively small area. As such, the ultimate load carrying ability of the retainer body  65  is reduced. By decreasing the width between the first planar end  84  and the second planar end  86 , the surface area of the first planar end  84  and the surface area of the second planar end  86  are caused to increase to provide a larger surface area to support increased loading. The manner of laterally supporting the retainer body  65  with a reduced width is described below. 
     FIG. 8  illustrates the first spacer  66   a . The second spacer  66   b  is identical in construction to the first spacer  66   a . Thus, only the first spacer  66   a  will be described in detail. The first spacer  66   a  is a generally rectangular member adapted to be positioned between the first planar end  84  of the retainer body  65  and the first end adapter  24 . However, the spacer  66   a  may be formed to have a variety of configurations so long as the spacer  66   a  functions as described below. As best shown in  FIG. 1 , the first spacer  66   a  abuts the first end adapter  24  and the first planar end  84  of the retainer body  65  to support the retainer body  65  relative to the body assembly  12  and thus apply a specific preload on the retainer body  65 . As best shown in  FIG. 9 , the first spacer  66   a  is further adapted to be positioned between the body  22  and the valve member  14  such that the first spacer  66   a  abuts the body  22  and the valve member  14  to prevent movement of the retainer body  65  along the axis of the first trunnion  54 . 
   Referring again to  FIG. 8 , the spacer  66   a  has a central bore  94  extending from one side to the opposing side. The bore  94  is adapted to be aligned with the opening  87  of the retainer body  65  upon rotation of the retainer body  65  to the operating position. Upon the retainer body  65  being rotated to the operating position, the spacer  66   a  of appropriate size is connected to the retainer body  65  with a connector member  96  ( FIG. 10 ). Likewise, the spacer  66   b  is connected to the retainer body  65  to achieve the desired overall width of the retainer body  64 . The connector member  96  may be any suitable device capable of securing the spacer  66   a  to the retainer body  65 , such as a pin, bolt or screw. In addition, as illustrated in  FIG. 10 , the spacer  66   a  may be constructed to allow the spacer  66   a  to be adjusted inwardly and outwardly relative to the retainer body  65  by a pair of screws  98  disposed in the bores  95   a  and  95   b  to achieve the desired overall width of the bearing retainer  64 . With the spacers  66   a  and  66   b  connected to the retainer body  65 , the first and second end adapters  24  and  26  are connected to the body  22 . 
   Referring now to  FIGS. 11 and 12 , in instances when a body assembly  12   a  is of two piece construction where the body assembly  12   a  includes an end adapter  26   a  and a body  22   a  integrally formed with an end adapter, the planar end of the retainer body  65  is positioned adjacent the integrally formed end adapter upon rotation of the retainer body  65  to the operating position. Thus, the planar end of the retainer body  65  is not accessible for connection of the spacer  66   b .  FIG. 11  illustrates a ring spacer  100  positionable between the retainer body  65  and the body  22 . The ring spacer  100  has a ring portion  102  and a spacer portion  104 . The ring portion  102  has a first surface  106 , a second surface  108 , an outer peripheral edge  110 , and inner peripheral edge  112 . The spacer portion  104  extends from the first surface  106  of the ring portion  102  and has an outer peripheral surface  114  extending coextensively with the outer peripheral edge  110  of the ring portion  102 . The spacer portion  104  further has an outer planar surface  116  adapted to abuttingly engage the first planar end  84  or the second planar end  86  and a planar surface  118  adapted to abuttingly engage the valve member  14 . 
   In use, the ring spacer  100  positioned in a valve chamber  28   a  in a concentric relationship with respect to the longitudinal flow axis  34   a  with the second surface  108  engaged with the body  22   a  and rotated to a position where the spacer portion  104  is in a non-interfering relationship with rotation of the retainer body  65  between the assembly position and the operating position. After insertion of the retainer body  65  into the valve chamber  28   a  and rotation of the retainer body  65  to the operating position, the ring spacer  100  is rotated to position the spacer portion  104  between the first planar end  84  of the retainer body  65  and the body  22   a . The ring spacer  100  may be rotated with any suitable device. A spacer  66   a  is positioned between the second planar end  86  of the bearing retainer  65  and the end adapter  26   a  in a substantially similar manner as described above. 
   Changes may be made in the combinations, operations and arrangements of the various parts and elements described herein without departing from the spirit and scope of the invention as defined in the following claims.