Abstract:
A valve includes a housing with a flow passage and a hole extending into the housing; a post with a base and a hole extending into the base, the post connected to the housing; and a dowel pin which sits in the hole of the housing and extends into the hole in the post.

Description:
BACKGROUND 
     The subject matter disclosed herein relates to valves and, more particularly, to the attachment of hinge pin posts to a valve housing. 
     Flapper valves, including dual flapper valves, utilize hinge pins, which are mounted on posts for rotation of the flappers. The precision and methodology used in mounting and locating the hinge pin is critical for proper operation and longevity of the valve. In general, there are two approaches for creating the mounting features for the hinge pin: integral and non-integral posts. For integral posts, the valve housing and the posts are formed together, typically by machining. With non-integral posts, the valve housing and the posts are formed separately and then joined together, typically with one or more fasteners. 
     SUMMARY 
     A valve includes a housing with a flow passage and a hole extending into the housing; a post with a base and a hole extending into the base, the post connected to the housing; and a dowel pin which sits in the hole of the housing and extends into the hole in the post. 
     A method of assembling a flapper valve includes press fitting a dowel pin into a hole in a valve housing; aligning a post with a hole in the base so that the dowel pin extends into the hole in the post base; and securing the post to the valve housing with a fastener. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a perspective view of one embodiment of a flapper valve. 
         FIG. 1B  is a cross-sectional view of the flapper valve of  FIG. 1A  along line B-B. 
         FIG. 1C  is a close-up view of a portion of  FIG. 1B   
         FIG. 1D  is a cross-sectional view of the flapper valve of  FIG. 1A  along line D-D. 
         FIG. 2A  is cross-sectional view of a second embodiment of a flapper valve. 
         FIG. 2B  is a close-up view of section  2 B of  FIG. 2A . 
         FIG. 2C  is a close-up view of section  2 C of  FIG. 2A . 
         FIG. 3A  is cross-sectional view of a third embodiment of a flapper valve. 
         FIG. 3B  is a close-up view of section  3 B of  FIG. 3A . 
         FIG. 3C  is a close-up view of section  3 C of  FIG. 3A . 
         FIG. 4A  is cross-sectional view of a fourth embodiment of a flapper valve. 
         FIG. 4B  is a close-up view of section  4 B of  FIG. 4A . 
         FIG. 4C  is a close-up view of section  4 C of  FIG. 4A . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1A  is a perspective view of one embodiment of flapper valve  10 ,  FIG. 1B  is a cross-sectional view of flapper valve  10  along line B-B,  FIG. 1C  is a close-up view of a portion of flapper valve  10 , and  FIG. 1D  is a cross-sectional view of flapper valve  10  along line D-D. 
     Flapper valve  10  includes valve housing  12 , posts  14 , hinge pin  16 , stop pin  18 , flappers  20 , dowel pins  22 , and fasteners  24 . In this embodiment, valve housing  12  includes two bores (which are not shown as they are covered by flappers  20  in  FIGS. 1A-1B ) and two holes  26  which extend into housing  12 , and four bores  28  which extend through housing  12 . Each post  14  includes a base  29  and a hole  30  which extends into post  14  at base  29 . In the embodiment shown, fasteners  24  are bolts with self-locking nuts, though they can be other types of fasteners in other embodiments. For simplicity, pins are shown without cross-hatching. 
     Dowel pins  22  sit in holes  26 , and can be press-fit into valve housing  12 . Hinge pin  16  and stop pin  18  extend through flappers  20 , so that flappers  20  can rotate relative to hinge pin  16 . Hinge pin  16  and stop pin  18  fit into posts  14  on each end. Posts  14  connect to housing  12  by aligning so that dowel pins  22  extend into holes  30 . Posts  14  can be slip fit onto dowel pins  22 , and then fasteners  24  can be used to secure posts  14  to housing  12 . Once posts  14  have been secured to housing  12 , flappers  20  can selectively rotate around hinge pin  16  to selectively restrict or allow flow through valve  10 . 
     As can be seen in  FIG. 1D , dowel pin  22  is cylindrical in shape and can be chamfered on one or both ends, which can help engagement with hole  30 , hinge pin  16  and/or hole  26 . Dowel pin  22  can be made of steel, stainless steel or any other material depending on valve  10  requirements. Dowel pins  22  typically extend in length at least one and a half times a diameter of dowel pin  22  into each of housing  12  and post  14 . For example, dowel pin  22  may extend twice its diameter in length into housing  12  and one and a half times its diameter in length into post  14 . The extension of dowel pins  22  into both posts  14  and housing  12  can vary depending on structural loads on posts  14 . 
     By using dowel pin  22 , which extends from hole  26  in housing  12  into hole  30  in post  14 , valve  10  is able to use non-integral posts while maintaining precise post  14  location for holding hinge pin  16  to maintain proper operation and longevity of valve  10 . As mentioned above, valve  10  could typically be made with either integral or non-integral posts. Integral posts require much more material and can be quite difficult to manufacture due to the shape of the housing  12  and posts  14 . Thus, making posts  14  non-integral to housing  12  can save manufacturing materials and costs, but a significant disadvantage of non-integral posts is that the location and fit of hinge pin  16  ends up being less precise as compared to integrally machined posts. This can be due to the mounting of the posts, for example, screw fasteners can cause the posts to be slightly skewed. By using dowel pin  22 , which can be press fit into housing  12 , posts  14  can be precisely aligned so that dowel pin extends into hole  30 . This greatly mitigates the disadvantages of using non-integral posts  22  in valve  10 , and can further provide shear capability and therefore better structural integrity of valve  10 , as fasteners  24  are typically not designed to be put under a shear load. 
     Using dowel pin  22  to connect posts  14  to housing  12  allows for a relatively simple, inexpensive and robust system for hinge pin  16  retention and allows for valve  10  to acquire the benefits of using non-integral posts  14 . Manufacturing posts  14  non-integral to housing  12  can allow for posts  14  and housing  12  to be made of different materials, for example, lower weight aluminum housing  12  and higher wear stainless steel posts  14 , for system optimization depending on needs. Using non-integral posts  14  can allow for better repairability and maintainability of valve  10 , as posts  14  can be replaced instead of having to replace entire valve housing  12  and posts  14  (as in integral system). 
       FIG. 2A  is cross-sectional view of a second embodiment of a flapper valve  10  and  FIG. 2B  is a close-up view of section  2 B of  FIG. 2A , and  FIG. 2C  is a close-up view of section  2 C of  FIG. 2A . Valve  10  includes housing  12  (with holes  26 ), posts  14  (with holes  30 ), hinge pin  16 , stop pin  18 , flappers  20 , dowel pins  32 , and fasteners  24 . In this embodiment, hinge pin  16  includes bore  34  and bore  36  extending into hinge pin  16 . 
     Valve  10  operates in the same manner as valve  10  of  FIGS. 1A-1D . However, in the embodiment of  FIGS. 2A-2C , dowel pin  32  extends into bore  34  of hinge pin  16  and dowel pin  32  extends into bore  36  of hinge pin  16 . The chamfered end of dowel pins  32  engage bores  34 ,  36 . Bore  34  can be shaped with a diameter just larger than the diameter of dowel pin  32  to securely fit with dowel pin  32 . Bore  36  has a larger diameter than dowel pin  32  to allow for thermal expansion, particularly when using different materials for different parts of valve  10 . In other embodiments, both bores  34 ,  36  could be larger or neither bore  34 ,  36  could be larger. 
     By extending dowel pins  32  into bores  34 ,  36  in hinge pin  16 , dowel pins  32  can help to retain hinge pin  16  axially, preventing any sliding movement of hinge pin  16  within posts  14 . As in  FIGS. 1A-1D , dowel pin  32  allows for the use of non-integral posts while maintaining precise post  14  location for holding hinge pin  16 . Dowel pin  32  further extends into bores  34 ,  36  to provide additional support for maintaining axial location of hinge pin  16 , thereby maintaining proper operation and longevity of valve  10 . 
       FIG. 3A  is cross-sectional view of a third embodiment of flapper valve  10 ,  FIG. 3B  is a close-up view of section  3 B of  FIG. 3A , and  FIG. 3C  is a close-up view of section  3 C of  FIG. 3A . Valve  10  includes housing  12  (with hole  26 ), posts  14  (with hole  30 ), hinge pin  16 , stop pin  18 , flappers  20 , dowel pin  40 , and fasteners  24 . In this embodiment, hinge pin  16  includes circumferential grooves  42 ,  44  extending into hinge pin  16 . 
     In the embodiment of  FIGS. 3A-3C , dowel pin  40  is flat on one end and spherical on the other end. Circumferential groove  42  is shaped to be complementary in shape to the spherical end of dowel pin  40 . Circumferential groove  44  is larger than circumferential groove  42  to accommodate thermal expansion of  10  valve components. In other embodiments, both circumferential grooves  42  and  44  could be larger or neither circumferential grooves  42  and  44  could be larger. 
     By using dowel pin  40  with spherical end and circumferential grooves  42 ,  44 , dowel pin  40  axially retains hinge pins  16 , and can provide for an easier assembly of valve  10 , as the rotation of hinge pin  16  would not need to be precise when setting posts  14  (with hinge pin  16 ) on dowel pins  40 . 
       FIG. 4A  is cross-sectional view of a fourth embodiment of flapper valve  10 ,  FIG. 4B  is a close-up view of section  4 B of  FIG. 4A , and  FIG. 4C  is a close-up view of section  4 C of  FIG. 4A . Valve  10  includes housing  12  (with hole  26 ), posts  14  (with hole  30 ), hinge pin  16 , stop pin  18 , flappers  20 , dowel pin  46 , and fasteners  24 . In this embodiment, hinge pin  16  includes bores  48  and  50  extending through hinge pin  16 . 
     In the embodiment of  FIGS. 4A-4C , bores  48  and  50  extend all of the way through hinge pin  16 . Bore  48  is shaped to be a close fit with the outer circumference of dowel pin  46 , and bore  50  is larger to accommodate thermal expansion. As in other embodiments, dimensions and sizing of bores  48 ,  50  can be different. Dowel pins  46  are of a length to extend most or all of the way through bores  48 ,  50 . 
     Dowel pins  46  can help in both the precise location of posts  14 , and can also provide axial retention of hinge pin  16  by extending through bores  48 ,  50 . Additionally, extending bores  48 ,  50  all the way through hinge pin  16  may make them easier and less expensive for manufacturing. 
     In summary, by using dowel pins  22 ,  32 ,  40 ,  46  to extend between valve housing  12  and posts  14 , non-integral posts can be used for valve  10  while maintaining proper post  14  and therefore hinge pin  16  position. This can help to increase life of valve and add shear strength to connection between posts  14  and housing  12 , as well as allow for the other benefits which flow from using non-integral posts, for example, the ability to optimize materials used, savings in manufacturing materials and costs, better repairability and maintainability of parts, and the ability to use common posts across similar sized valves  10  which can enable modular valve design. All of these can result in an overall increase in the life and durability of valve  10 . 
     While  FIGS. 1A-4C  show flapper valve  10 , this is for example purposes only, and other types of valves could use non-integral posts with one or more dowel pins, for example, butterfly valves. 
     While the invention has been described with reference to an exemplary embodiment(s), it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment(s) disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.